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BACKGROUND OF THE INVENTION This invention relates to the recovery of useful materials from waste materials and more particularly to the treatment of sludge formed in tin plating baths to recover useful quantities of tin compounds and ferrocyanide compounds for recycling. Among the commercial processes used to produce tin plated steel strip is the so-called Halogen Tin Electro-deposition process. In this process, pickled and washed steel strip is passed into a bath containing a complex stannous fluoride anion, thought to be SnF 6 .sup. 4 - (hexafluorostannate(II)), sodium bifluoride, hydrochloric acid and minor amounts of various addition agents such as grain refiners, all as well known to those skilled in the art. The strip is made cathodic as it passes into the bath and a metallic tin anode is immersed in the bath. In operation, an electric current is applied causing the stannous fluoride complex ion to approach the cathodic steel strip surface where it is reduced to metallic tin, resulting in the deposition of a layer of tin on the steel strip. One of the disadvantages of this halogen tin process is that the bath tends to accumulate an ever increasing amount of sludge during operation, the major component of which sludge is sodium hexafluorstannate(IV), Na 2 SnF 6 , together with some hydrated stannic oxide, SnO 2 .xH 2 O. The hexafluorostannate (IV) complex is formed by air oxidation of the hexafluorostannate(II) complex. This oxidation of stannate(II) to stannate(IV) results from the entrapment of air in the plating solution due to vigorous agitation of the plating bath caused by the high line speed of the strip. Although the oxidation is kinetically slow, the rate may be catalytically increased in the presence of dissolved iron, which is present in the plating bath due, at least in part, to incomplete washing of the strip following the acid pickle. In order to minimize the amount of ferrous ion present in the electroplating bath, and, thereby, prevent catalysis of the hexafluorostannate(II)/hexafluorostannate(IV) oxidation, sodium ferrocyanide, Na 4 [Fe(CN) 6 ].10H 2 O, is periodically added to the bath. The ferrocyanide ion, Fe(CN) 6 .sup. 4 - , has great affinity for ferrous ion, and will readily combine therewith to form a so called ferro-ferrocyanide complex ion which will precipitate from the bath solution as Fe 2 Fe(CN) 6 . This salt is, in turn, slowly oxidized by the air which is drawn into the bath, to ferriferrocyanide Fe 4 [Fe(CN) 6 ] 3 , which along with the Na 2 SnF 6 and SnO 2 .xH 2 O then forms a portion of the bath sludge which must be periodically removed. Sodium ferrocyanide additions are then made periodically in order to replenish the ferrocyanide available to remove any ferrous ion present. The bath sludge is of commercial value due to the presence of the high-grade tin source compound, Na 2 SnF 6 , and a well known process is customarily used for its recovery. This process involves treating the sludge with a sufficient volume of hot water to leach the majority of the Na 2 SnF 6 from the sludge. The insoluble matter remaining, which is hereafter called secondary sludge, is removed from the hot water solution and, depending on the tin content, discarded or sold to a smelter. The clear solution remaining is then further processed to obtain a tin bearing compound or metallic tin. Thus the presently used process for halogen tin sludge treatment fails to recover any of the ferrocyanide present in the halogen tin bath sludge. The failure to extract the ferrocyanide portion results in both an increased cost of the tin plating operation itself (due to a constant need for fresh sodium ferrocyanide) and a potential pollution problem due to the cyanide content of the secondary sludge which must be discarded. SUMMARY We have discovered a novel process of treating halogen tin sludge which results both in an increased efficiency in chemical tin recovery and in a recovery of ferrocyanide. Furthermore, our process may be used either on the initial sludge as removed from the bath, or on the secondary sludge, following the conventional hot water extraction. Finally, our process is operative over a wide temperature range. In our process, halogen tin bath sludge is hydrolyzed in alkaline media to form hexahydroxostannate(IV) ion, Sn(OH) 6 .sup. 2 - , and ferrocyanide ion, Fe(CN) 6 .sup. 4 - . After filtering the alkaline solution to remove iron oxides and other residual insolubles, the solution pH is lowered by addition of a mineral acid solution to a point at which the Sn(OH) 6 .sup. 2 - is neutralized to form hydrated stannic oxide, SnO 2 xH 2 O. This tin precipitate is then removed to leave a solution containing ferrocyanide ion together with the acid and alkali counter ions. This final solution may be either concentrated and returned to the halogen tin bath as a source of ferrocyanide, or solid alkali metal ferrocyanide precipitated and purified by any one of several means well known to those skilled in the art. BRIEF DESCRIPTION OF THE DRAWINGS The FIGURE shows a schematic representation of the steps in the process of recovering hydrated stannic oxide and ferrocyanide from halogen tin electrodeposition bath sludge. DETAILED DESCRIPTION OF THE INVENTION A typical halogen tin electrodeposition bath will initially contain hydronium, H 3 O + , fluoride, F - , sodium, Na + , hexafluorostannate(II) complex, SnF 6 .sup. 4 - , ions, and addition agents. During the plating operation, dissolved iron will be introduced into the bath due, at least in part, to the incomplete washing of the steel strip subsequent to acid pickling. In addition, molecular oxygen, O 2 , will be introduced into the solution as a result of the surface turbulence due to the high speed of the steel strip as it passes through the bath. The dissolved oxygen will oxidize the hexafluorostannate(II) to hexafluorstannate(IV) according to equation I: 4h.sub.3 o.sup.+ + 4na.sup.+ + 2SnF.sub.6 .sup.4 .sup.- + 0.sub.2 → 2Na.sub.2 [SnF.sub.6 ] + 6H.sub.2 O; (I) some of which will subsequently hydrolyze according to equation Ia: Na.sub.2 SnF.sub.6 + 2H.sub.2 O → SnO.sub.2 + 4H.sup.+ + 2Na.sup.+ + 6F.sup.-. (Ia) As discussed previously, dissolved iron, present in the bath, catalyzes Equation (I), increasing the reaction rate and thus aggravating the loss of the active plating ingredient, according to the following reactions: 4H.sub.3 O.sup.+ + 4Fe(H.sub.2 O).sub.6.sup.2.sup.+ + 0.sub.2 → 4Fe(H.sub.2 O).sub.6.sup.3 .sup.+ + 6H.sub.2 O (Ib) 2Fe(H.sub.2 O).sub.6.sup.3 .sup.+ + SnF.sub.6.sup.4.sup.- → SnF.sub.6.sup.2 .sup.- + 2Fe(H.sub.2 O).sub.6.sup.2 .sup.+ (Ic) For this reason, sodium ferrocyanide is added to the bath and a concentration thereof of approximately 1 gram per liter is maintained by periodic addition. The ferrocyanide eliminates any iron(II) catalysis of Equation (I) by precipitating the iron(II) according to the equation: 2Fe.sub.aq.sup.2 .sup.+ + Fe(CN).sub.6.sup.4 - → Fe.sub.2 [Fe(CN).sub.6 ] (II) the precipitate from Equation (II) is slowly oxidized in the presence of dissolved oxygen and excess sodium ferrocyanide according to the equation: 4H.sub.3 O.sup.+ + 2Fe.sub.2 [Fe(CN).sub.6 ] + [Fe(CN).sub.6 ].sup.4 .sup.- + 0.sub.2 → Fe.sub.4 [Fe(CN).sub.6 ].sub.3 + 6H.sub.2 O (III) the solid precipitates from equations I, Ia, II and III, then, form a substantial portion of the sludge which accumulates in the bath over a period of time. At intervals, therefore, the plating operation is shut down, the accumulated sludge removed, and the sludge treated to recover the tin in the Na 2 [SnF 6 ] and SnO 2 and the ferrocyanide in the Fe 2 [Fe(CN) 6 ] and Fe 4 [Fe(CN) 6 ] 3 . This is accomplished, in accordance with the present invention, by preparing a slurry of the sludge with a pH of from about 10 to about 14. Preparation of this alkaline slurry may be accomplished either by adding a sufficient amount of an alkali metal hydroxide to an aqueous slurry of the sludge or by slurrying the pure sludge in an already basic solution. Both alternative methods are equally effective for our purpose and both are contemplated within this process. Preparation of this alkaline slurry results in the basic hydrolysis of the components as follows: Na.sub.2 [SnF.sub.6 ] + 6OH.sup.- → 2Na.sup.+ + 6F.sup.- + Sn(OH).sub.6.sup. 2 .sup.- (IV) snO.sub.2 + 2H.sub.2 O + 2OH.sup.- → Sn(OH).sub.6 .sup.= (IVa) Fe.sub.2 [Fe(CN).sub.6 ] + 4OH.sup.- → 2FeO + Fe(CN).sub.6 .sup.-.sup.4 + 2H.sub.2 O (V) fe.sub.4 [Fe(CN).sub.6 ].sub.3 + 12OH.sup.- → 2Fe.sub.2 O.sub.3 + 3Fe(CN).sub.6 .sup.4 .sup.- + 6H.sub.2 O (VI) as these reactions are heterogeneous, i.e. reaction of a solid with a solution, heating and/or stirring, which increase the solid/liquid interaction, will increase the rate of reactions (IV)-(VI). Our data indicates that, although the ferrocyanide dissolution (V and VI) is rapid even at room temperature, the stannic oxide dissolution (IVa) time is reduced from approximately 30 hours at 20°-25° C to approximately 2 hours at 60°-65° C. Indeed our process is effective at temperatures up to 80° C, above which temperature oxidation of ferrocyanide to ferricyanide becomes operative in alkaline media. We prefer, however, to use vigorous stirring and temperatures of approximately 60°-65° C which decrease the reaction time, yet avoid significant oxidation. Upon completion of base hydrolysis, which is evidenced by the pH remaining stable after alkali addition has been stopped, the solution is centrifuged or filtered hot to remove the iron-rich, insoluble material. This material may either be discarded or further processed as a high grade iron ore by well known methods. The clear centrifugate of filtrate, at a temperature of not more than 60°-65° C, is then neutralized to a solution pH of from about 6.5 to about 7.5 with a solution of either HF or HCl which results in the precipitation of hydrated stannic oxide according to the reaction Sn(OH).sub.6.sup.2 .sup.- + 2H.sub.3 O.sup.+ → SnO.sub.2.xH.sub.2 O. (VII) the slurry is then centrifuged or filtered to give a solid mass of SnO 2 .xH 2 O and a solution containing ferrocyanide ion. This final ferrocyanide solution is then either concentrated and added directly to the halogen tin bath as a ferrocyanide source or further treated by well known means to isolate solid alkali metal ferrocyanide. Referring to the drawing, the halogen tin bath sludge, either initial or secondary, containing Na 2 SnF 6 , SnO 2 , Fe 2 [Fe(CN) 6 ] and Fe 4 [Fe(CN) 6 ] 3 , is placed in a slurry chamber 10. Water and alkali metal hydroxide solution are introduced into slurry chamber 10 via lines 12 and 14 respectively. The resulting slurry is fed, via line 16, into reactor 18 which is equipped with stirring and heating means, shown respectively as a stirrer 19 and a heating coil 20. After reaction is complete, the slurry is transferred via line 21 to centrifuge 24, where it is centrifuged to separate the ferrous and ferric oxides, and other insoluble material, from the solution containing the tin and ferrocyanide ions. The centrifugate or separated liquid is transferred through line 28 to a reactor 30. The separated solid is then washed while still in centrifuge 24 with water from line 22, centrifuged again, and the centrifugate transferred to reactor 30 via line 28. The solid material is then removed from the reactor 24 and either discarded or used as a high grade iron ore. The combined solution in reactor 30 is allowed to cool and an HF or HCl solution is introduced via line 32. Addition of acid is continued until the solution pH is between about 6.5 to about 7.5. The resultant solution containing the SnO 2 .xH 2 O is transferred, via line 32, to centrifuge 36 where it is centrifuged. The clear centrifugate is drawn, through line 40, by pump 42, and directed through line 44 to evaporator 46. The hydrated stannic oxide remaining in centrifuge 36 is washed with water from line 34 and the washings are also pumped to the evaporator 46. The washed hydrated stannic oxide is then removed at 38 for use as a high grade tin ore. The combined centrifugate/wash solution in evaporator 46 is then concentrated by evaporation induced by heating coil 47, with simultaneous stirring by stirrer 49 to a ferrocyanide concentration of the equivalent of not less than 10 grams per liter of Na 4 [Fe(CN) 6 ].10H 2 O. The concentrated ferrocyanide solution removed from evaporator 46 via line 50 may, alternatively, either be used as a source of ferrocyanide for direct halogen tin bath addition, or may be treated by any well known means, such as further evaporation, fractional crystallization or ion exchange separation, to isolate pure alkali metal ferrocyanide. Water vapor removed by evaporation is removed via line 48 to suitable condensation means not shown. We, of course, do not wish to be limited by the specific apparatus noted herein. For example, standard filtration apparatus may be substituted for centrifuges 24 and 36 without, in any way, departing from the essence of our invention. In addition, the concentrations of acid and base, used herein are by no means critical. What is critical to the reactions here presented is the solution pH. Thus our process is operative with virtually any acid or base solution concentration, with, however, higher concentrations being preferred in order to reduce total solution volume. In the preferred embodiment, a 20% by weight aqueous slurry of secondary sludge is prepared. The slurry is warmed, to approximately 60°-65° C with stirring. 60°-65° C, 10M sodium hydroxide solution is added to the slurry with stirring until the pH of the solution remains stable at pH 12 after the addition is stopped. The resulting solution is centrifuged hot and the insoluble matter, containing iron oxides, is washed, dried and removed for further processing. To the warm combined centrifugate is added a 5M aqueous hydrochloric acid solution until a final pH of 6.5-7.5 is reached and maintained for at least 60 minutes after addition ceased. The solution is then centrifuged hot to remove the SnO 2 .xH 2 O formed during the neutralization which is then washed and centrifuged once more. The combined centrifugate is concentrated to a sodium ferrocyanide concentration of not less than 10 grams per liter preferably 25-50 g/l and then utilized as a source of ferrocyanide for direct bath addition. Utilization of the general procedures described allow substantially quantitative recovery of the valuable components in sludge formed in a halogen tin bath. Such recovery not only reduces the demand for fresh starting materials in the plating operation, but also reduces the environmental hazard in the disposal of cyanide containing, secondary sludge.

A process for the extraction and recovery of hydrated stannic oxide and alkali metal ferrocyanide from the sludge formed in a halogen tin electrodeposition bath is described. The process comprises dissolving the ferrocyanide compounds and the tetravalent tin compounds present in the sludge in an alkaline medium, removing any insoluble materials, precipitating hydrated stannic oxide from the solution by neutralization of the solution, and separating the hydrated stannic oxide from the solution which then contains ferrocyanide ion together with acid and base counterions.

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation of U.S. application Ser. No. 12/791,533, filed Jun. 1, 2010, now allowed, which is a continuation of U.S. application Ser. No. 10/382,467, filed Mar. 6, 2003, now U.S. Pat. No. 7,728,653, which claims the benefit of a foreign priority application filed in Japan as Serial No. 2002-059903 on Mar. 6, 2002, all of which are incorporated by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to techniques for a semiconductor integrated circuit and its driving method. The invention also relates to a light emitting device that has a semiconductor integrated circuit of the present invention in its driving circuit portion and a pixel portion, in particular, an active matrix light emitting device which has a semiconductor integrated circuit of the present invention as a signal line driving circuit in a driving circuit portion, which has a plurality of pixels arranged so as to form a matrix pattern, and which has a switching element and a light emitting element in each of the pixels. [0004] 2. Description of the Related Art [0005] In recent years, development of light emitting devices using self-luminous light emitting elements has progressed. Making good use of advantages such as high quality image, thinness and lightweightness, such light emitting devices are widely used in display screens of mobile phones and personal computers. In particular, light emitting devices using light emitting elements are characteristic in that they have suitably fast response speed for animated displays, and low voltage and low power consumption driving. Thus, light emitting devices using light emitting elements are expected to be widely used for various purposes, including new-generation mobile telephones and personal digital assistants (PDAs) and are attracting attention as the next-generation displays. [0006] An example of a light emitting element is an organic light emitting diode (OLED) with an anode and a cathode, and has a structure in which an organic compounded layer is sandwiched between the aforementioned anode and cathode. The organic compound layer generally has a laminate structure of which is represented by a laminate structure of “hole transport layer, light emitting layer, and electron transport layer”, proposed by Tang, Eastman Kodak Company. [0007] In order to make a light emitting element emit light, the semiconductor device which drives the light emitting element is formed of polysilicon (polycrystalline silicon) which has a large ON current. The amount of current that flows into the light emitting element and the luminescence of the light emitting element are in direct proportion to each other, whereby the light emitting element emits light having luminescence in accordance with the amount of current which flows to the organic compound layer. Also, as the semiconductor device that drives the light emitting element, a polysilicon transistor formed of polysilicon is used. [0008] However, when displaying a multi-gray scale image using a light emitting device with a light emitting element, a method of driving the device such as an analog gray scale method (analog driving method), or a digital gray scale method (digital driving method) can be given. The difference between the two lies in their methods of controlling the light emitting element in the state of light emission or non-light emission. The former analog gray scale method uses an analog method of controlling the current that flows into the light emitting element thereby obtaining gray scale. The latter digital gray scale method uses a method in which the light emitting element is driven in only two states, an ON state (almost 100% luminescence), and an OFF state (almost 0% luminescence). [0009] Further, proposed is a current input method with which it is possible to classify the type of signal that is inputted into the light emitting device using the light emitting element as an example. In this current input method, it is supposed control of the amount of current that flows to the light emitting element is possible without being influenced by the TFT which drives the light emitting element. [0010] The current input method is applicable to both the analog gray scale method and the digital gray scale method mentioned above. The current input method is a method where a video signal inputted into a pixel is a current and the luminescence of the light emitting element can be controlled by flowing current according to the inputted video signal (current) into the light emitting element. [0011] Next, an example of a circuit construction of a pixel using a current input method and a driving method thereof in light emitting device will be explained with reference to FIG. 14 . In FIG. 14 , a pixel has a signal line 1401 , first to third scanning lines 1402 to 1404 , a power source line 1405 , transistors 1406 to 1409 , a capacitor element 1410 , and light emitting element 1411 . A current source circuit 1412 is provided to the signal line. [0012] The transistor 1406 has a gate electrode connected to the first scanning line 1402 . A first electrode of the transistor 1406 is connected to the signal line 1401 whereas its second electrode is connected to a first electrode of the transistor 1407 , a first electrode of the transistor 1408 , and a first electrode of the transistor 1409 . The transistor 1407 has a gate electrode connected to the second scanning line 1403 . A second electrode of the transistor 1407 is connected to a gate electrode of the transistor 1408 . A second electrode of the transistor 1408 is connected to the current line 1405 . The transistor 1409 has a gate electrode connected to the third scanning line 1404 . A second electrode of the transistor 1409 is connected to one of electrodes of the light emitting element 1411 . The capacitor element 1410 is connected between the gate electrode and second electrode of the transistor 1408 to hold the gate-source voltage of the transistor 1408 . The current line 1405 and a cathode of the light emitting element 1411 receive given electric potentials to hold an electric potential difference with each other. [0013] Operations from video signal writing to light emission will be described next. First, pulses are inputted to the first scanning line 1402 and the second scanning line 1403 to turn the transistors 1406 and 1407 ON. A signal current flowing in the signal line 1401 at this point is denoted by I data and is supplied from the current source circuit 1412 . [0014] Right after the transistor 1406 is turned ON, no electric charges are held in the capacitor element 1410 yet and therefore the transistor 1408 remains OFF. In other words, a current caused by electric charges accumulated already in the capacitor element 1410 alone is flowing at this point. [0015] Thereafter, electric charges are gradually accumulated in the capacitor element 1410 to cause a difference in electric potential between the electrodes. As the electric potential difference between the electrodes reaches a threshold Vth of the transistor 1408 , the transistor 1408 is turned ON to generate a current flow. The current flowing into the capacitor element 1410 then is gradually reduced. However, the reduced current does not stop ongoing accumulation of electric charges in the capacitor element 1410 . [0016] Accumulation of electric charges in the capacitor element 1410 continues until the electric potential difference between its two electrodes, namely, the gate-source voltage of the transistor 1408 , reaches a given voltage, which is a voltage (V GS ) high enough to cause the current I data to flow in the transistor 1408 . When the accumulation of electric charges is finished, the current I data continues to flow in the transistor 1408 . A signal writing operation is conducted as above. Lastly, the first scanning line 1402 and the second scanning line 1403 stop being selected to turn the transistors 1406 and 1407 OFF. [0017] A light emission operation follows next. A pulse is inputted to the third scanning line 1404 to turn the transistor 14090 N. With the transistor 1408 turned ON by V GS which is written in the preceding operation and kept in the capacitor 1410 , a current flows from the current source line 1405 . This causes the light emitting element 1411 to emit light. If the transistor 1408 is set to operate in a saturation range at this point, a light emission current I EL flowing in the light emitting element 1411 does not deviate from I data even when the source-drain voltage of the transistor 1408 is changed. [0018] As described above, the current input method refers to a method in which a drain current whose current value is equal to or in proportion to the signal current value set by the current source circuit 1412 flows between the source and drain of the transistor 1408 and the light emitting element 1411 emits light with a luminance according to the drain current. By employing a current input method pixel as the one described in the above, influence of fluctuation in characteristic between transistors that constitute the pixel can be reduced and a desired current can be supplied to its light emitting element. Other current input method pixel circuits have been reported in U.S. Pat. No. 6,229,506 B1 and JF 2001-147659 A. [0019] In a light emitting device employing the current input method, a signal current exactly reflecting a video signal has to be inputted to a pixel. However, when polysilicon transistors are used to build a driving circuit that inputs a signal current to a pixel (the circuit corresponds to the current source circuit 1412 in FIG. 14 ), characteristic fluctuation between the polysilicon transistors leads to fluctuation in signal current and unevenness in an image displayed. The characteristic fluctuation is caused by defects in crystal growth direction and grain boundaries, nonuniformity in thickness of the laminate; and insufficient accuracy in patterning a film. Because of large fluctuation between the polysilicon transistors, it is difficult to generate an accurate signal current and an image displayed will be full of streaks running vertically. [0020] In other words, influence of characteristic fluctuation between transistors constituting a driving circuit that inputs a signal current to a pixel has to be reduced in a light emitting device employing the current input method. This means that influence of characteristic fluctuation has to be reduced both in transistors that constitute the driving circuit and in transistors that constitute a pixel. SUMMARY OF THE INVENTION [0021] The present invention has been made in view of the above problems, and an object of the present invention is therefore to provide a semiconductor integrated circuit which reduces influence of transistor characteristic fluctuation between current sources of a current source circuit until the transistor characteristics do not affect the circuit, as well as a method of driving the semiconductor integrated circuit. [0022] Another object of the present invention is to provide a light emitting device having a driving circuit portion that has the semiconductor integrated circuit and a pixel portion. [0023] Particularly, an object of the present invention is to provide an active matrix light emitting device which has the semiconductor integrated circuit as a signal line driving circuit in a driving circuit portion, which has a plurality of pixels arranged so as to form a matrix pattern, and which has a switching element and a light emitting element in each of the pixels. [0024] Another object of the present invention is to provide a light emitting device in which semiconductor elements of a pixel portion and driving circuit portion are composed of polysilicon thin film transistors to integrally form the pixel portion and the driving circuit portion on the same substrate. [0025] A current source circuit is composed of one or more current sources. One current source has one or more transistors. A current source that supplies a constant current is called a constant current source. [0026] A semiconductor integrated circuit of the present invention is characterized by having signal lines, a current source circuit that outputs a current to be inputted to the signal lines, and means for switching current source circuits connected to the signal lines each time a given period passes (hereinafter simply referred to as switching means. The switching means has a plurality of circuits that have a switching function, and therefore is also called a switching circuit). [0027] The switching means of the present invention switches current sources connected to signal lines and accordingly switches currents inputted to the signal lines at given intervals even when there is fluctuation in current outputted from the current source circuit. Therefore, the amount of current flowing into a light emitting element, namely, the luminance, is seemingly evened out over time and display unevenness can be solved. A light emitting device that is not influenced by transistor characteristic fluctuation is thus provided. BRIEF DESCRIPTION OF THE DRAWINGS [0028] In the accompanying drawings: [0029] FIG. 1 is a diagram showing the structure of a semiconductor integrated circuit of the present invention; [0030] FIG. 2 is a diagram showing the structure of a semiconductor integrated circuit of the present invention; [0031] FIG. 3 is a diagram showing the structure of a semiconductor integrated circuit of the present invention; [0032] FIG. 4 is a timing chart of a signal line driving method of the present invention; [0033] FIG. 5 is a diagram showing the structure of a semiconductor integrated circuit of the present invention; [0034] FIG. 6 is a diagram showing the structure of a semiconductor integrated circuit of the present invention; [0035] FIG. 7 is a diagram showing the structure of switching means in a semiconductor integrated circuit of the present invention; [0036] FIG. 8 is a diagram showing the structure of a semiconductor integrated circuit of the present invention; [0037] FIG. 9 is a diagram showing the structure of a semiconductor integrated circuit of the present invention; [0038] FIG. 10 is a diagram showing the structure of a semiconductor integrated circuit of the present invention; [0039] FIGS. 11A to 11C are timing charts of a signal line driving method of the present invention; [0040] FIGS. 12A and 12B are diagrams showing the structure of a light emitting device of the present invention; [0041] FIGS. 13A and 13B are diagrams showing the structure of a semiconductor integrated circuit of the present invention; [0042] FIG. 14 is a circuit diagram of a pixel of a light emitting device; and [0043] FIGS. 15A to 15H are diagrams showing electronic equipment to which a light emitting device of the present invention is applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment Mode [0044] An outline of a semiconductor integrated circuit of the present invention, as a signal line driving circuit, will be described with reference to FIG. 6 . For easy understanding, FIG. 6 focuses on three current sources C(i), C(i+1), and C(i+2) of a current source circuit and on a signal line S(m) for supplying a current to a pixel. [0045] As shown in FIG. 6 , the current sources C(i), C(i+1), and C(i+2) are connected to the signal line S(m) through switching means. The present invention is characterized in that the switching means chooses a current to be inputted to the signal line S(m) out of a current I(i), a current I(i+1), and a current I(i+2) from the three current sources C(i) to C(i+2) and switches from one current to another each time a given period passes. [0046] The switching means is described next. FIG. 7 shows the structure of the switching means. The current sources C(i), C(i+1), and C(i+2) respectively have characteristics that make the currents I(i), I(i+1), and I(i+2) to flow. The current sources C(i), C(i+1), and C(i+2) are placed such that they can be connected to the signal line S(m) through a switch. A signal is inputted to the switch and, according to the signal, the switch connects the signal line S(m) to one of the current sources C(i), C(i+1), and C(i+2). [0047] When the switch establishes a connection with the current source C(i), the current I(i) flows into the signal line S(m). When the switch establishes a connection with the current source C(i+1), the current I(i+1) flows into the signal line S(m). When the switch connects with the current source C(i+2), the current I(i+2) flows into the signal line S(m). In short, the current to be flown into the signal line S(m) is switched among I(i), I(i+1), and I(i+2). [0048] The example illustrated by FIGS. 6 and 7 focuses on one signal line and three current sources for easy understanding. However, an actual signal line driving circuit has plural signal lines and current sources as shown in the following embodiments. The switch serving as the switching means in FIG. 7 has a terminal but, in practice, the switching function is provided by an analog switch or like other circuits as shown in the following embodiments. [0049] A period, for switching within this given period is very short. Therefore, an image displayed seems uniform to the human eye even when there is difference in characteristics between current sources, namely, fluctuation in current supplied from a current source. [0050] With the switching means described above, the present invention obtains a semiconductor integrated circuit having a current source circuit which is not influenced by transistor characteristics. This makes it possible to provide a light emitting device which can supply a desired signal current to a light emitting element and which can display an image with no unevenness. [0051] To generalize the present invention using a function, the present invention is a semiconductor integrated circuit, comprised of: m signal lines S 1 , S 2 , . . . , and S m ; a current source circuit that has i current sources C 1 , C 2 , . . . , and C i ; and switching means that includes n switching units U 1 , U 2 , . . . , and U n , the circuit characterized in that: the n switching units are each connected to j current sources out of the i current sources; and the M-th signal line S M is connected to the N-th switching unit U N , and the switching unit U N is connected to the F 1 (N)-th current source, the F 2 (N)-th current source, the F 3 (N)-th current source, . . . , and the F j (N)-th current source which satisfy a function F k (x) (k=1˜j, x=1−n). [0052] The present invention is a semiconductor integrated circuit, comprised of: m signal lines S 1 , S 2 , . . . , and S m ; a current source circuit that has i current sources C 1 , C 2 , . . . , and C i ; and switching means that includes n switching units U 1 , U 2 , . . . , and U n , the circuit characterized in that: the n switching units are each connected to j current sources out of the i current sources; the M-th signal line S M is connected to the N-th switching unit U N , and the switching unit U N is connected to the F 1 (N)-th current source, the F 2 (N)-th current source, the F 3 (N)-th current source, . . . , and the F j (N)-th current source which satisfy a function F k (x) (k=1˜j, x=1˜n); and the (M−1)-th signal line S M-1 is connected to the (N−1)-th switching unit U N-1 , and the switching unit U N-1 is connected to the F 1 (N−1)-th current source, the F 2 (N−1)-th current source, the F 3 (N−1)-th current source, . . . , and the F j (N−1)-th current source which satisfy the function F k (x). [0053] In the present invention, adjacent switching units can share a current source. Using the above function, this is expressed as the current sources satisfying F 3 (N)=F 2 (N+1)=F 1 (N+2) when i=3, for example. In other words, adjacent switching units can share the N-th current source, the (N+1)-th current source, and the (N+2)-th current source. To give another example, current sources satisfy F 5 (N)=F 4 (N+1)=F 3 (N+2)=F 4 (N+3)=F 5 (N+4) when i=5, and adjacent switching units can share the N-th, (N+1)-th, (N+2)-th, (N+3)-th, and (N+4)-th current sources. [0054] As described, the present invention allows switching units to share current sources. This eliminates the border between one signal line and its adjacent signal line and makes a uniform current to flow in all signal lines. As a result, no border is formed in any part of the display screen to make it possible to provide a light emitting device with no streaks in a displayed image and no luminance unevenness. [0055] The present invention solves characteristic fluctuation among elements used in a semiconductor integrated circuit, and can provide the same effect when the elements whose characteristic fluctuation is to be controlled are transistors other than polysilicon transistors, for example, single crystal silicon transistors. Embodiment 1 [0056] In this embodiment, a semiconductor integrated circuit of the present invention is applied to a signal line driving circuit of a driving circuit portion and a specific description is given on a structure and driving method of a current source circuit of the signal line driving circuit. [0057] A specific example of the present invention is shown in FIG. 1 . The description given in this embodiment deals with current sources constituted of n-channel transistors. A transistor can take either the n-channel polarity or the p-channel polarity and, commonly, the polarity of a transistor is determined by the polarity of a pixel. When a current flows from a pixel toward a current source circuit, the polarity is desirably the n type. When a current flows from a current source circuit to a pixel, the polarity is desirably the p type. This is because fixing the source electric potential of a transistor is convenient. [0058] Shown in FIG. 1 are transistors Tr(i) to Tr(i+5), switching means, and signal lines S(m) to S(m+5). The transistors Tr(i) to Tr(i+5) constitute current sources C(i) to C(i+5), respectively. Gate electrodes of the transistors Tr(i) to Tr(i+5) are connected to a current control line and their source electrodes are connected to V SS . The current value is controlled by the voltage applied to the current control line. [0059] The gate electrodes of the transistors Tr(i) to Tr(i+5) here are connected to the same current control line for simplification. However, the transistors may be connected to different current control lines to have different current values by applying different levels of voltage to the current control lines. In this case, different transistors output currents to different destinations and voltages applied to the current control lines have to be switched in accordance with a switch in destination. [0060] If the transistors Tr(i) to Tr(i+5) have an identical characteristic, currents I(i) to I(i+5) are equal to one another. In reality, however, characteristic fluctuation among the transistors Tr(i) to Tr(i+5) is large and therefore the currents I(i) to I(i+5) are varied. The switching means of the present invention chooses a current to be inputted to a signal line out of the currents I(i) to I(i+5) and switches from one to another each time a given period passes. Accordingly, a current flowing in a light emitting element is also switched at given intervals. As a result, to the human eye, light emission is evened out over time and unevenness in luminance is reduced. [0061] FIG. 2 shows the structure of the switching means having analog switches (also called transfer gates). In FIG. 2 , components identical with those in FIG. 1 are denoted by the same symbols. The circuit is designed such that drain electrodes of the transistors Tr(i) to Tr(i+5) are connected to the signal lines S(m) to S(m+5). However, one signal line can be connected to three current sources. By a switching function, one out of three current sources is chosen for one signal line. [0062] For example, when a signal for selecting a terminal 1 is inputted to the switching means, the signal line S(m+1) is connected to the current source C(i), the signal line S(m+2) is connected to the current source C(i+1), and the subsequent signal lines and current sources are connected in a similar fashion. Next, a signal for selecting a terminal 2 is inputted to the switching means to connect the signal line S(m+1) to the current source C(i+1) and the signal line S(m+2) to the current source C(i+2), and the subsequent signal lines and current sources are connected in a similar fashion. Next, a signal for selecting a terminal 3 is inputted to the switching means to connect the signal line S(m+1) to the current source C(i+2) and the signal line S(m+2) to the current source C(i+3), and the subsequent signal lines and current sources are connected in a similar fashion. Currents from three current sources are thus alternately inputted to one signal line, thereby avoiding uneven display. [0063] To generalize this connection using the function that expresses the present invention, the current sources are set so as to satisfy F 1 (N)=N+a, F 2 (N)=N+b, and F 3 (N)=N+c (a, b, and c are integers and a≠b≠c) when i=3, and a=−1, b=0, and c=1. [0064] FIG. 3 shows a specific example in which analog switches are used for the switching means having a switching function. In FIG. 3 , components identical with those in FIG. 2 are denoted by the same symbols, and the current sources C(i) to C(i+5) have the transistors Tr(i) to Tr(i+5), respectively. [0065] Denoted by A(l) to A(l+2) and A(l)b to A(l+2)b in FIG. 3 are wires connected to plural analog switches. The analog switches are divided into groups and a group of analog switches is connected to one signal line (switching unit). In FIG. 3 , switching units U(n) to U(n+5) each have three analog switches and are connected to the signal lines S(m) to S(m+5), respectively. The switching units together form the switching means. [0066] In the current source C(i+1), the drain electrode of the transistor Tr(i+1) is connected to one of the analog switches of the switching unit U(n+1), one of the analog switches of the switching unit U(n), and one of the analog switches of the switching unit U(n+2). In short, a drain electrode of a transistor is connected to one analog switch chosen from each of three switching units. The rest of the current sources, C(i), C(i+2), C(i+3), C(i+4), and C(i+5), are similarly connected to their respective analog switches. [0067] When signals are inputted to the wires A(l) and A(l)b, an analog switch to be connected is chosen and turned conductive. Then a current flows from the current source connected with the selected analog switch to a signal line, for example, from the current source C(i+1) to the signal line S(m+2). Similarly, currents flow from the current sources C(i+1), C(i+3), C(i+4), C(i+5), and C(i+6) to the signal lines S(m), S(m+2), S(m+3), S(m+4), and S(m+5), respectively. This is referred to as Selection ( 1 ). [0068] Next, signals are inputted to the wires A(l+1) and A(l+1)b and an analog switch to be connected is chosen and turned conductive. Then a current flows from the current source connected with the selected analog switch to a signal line, for example, from the current source C(i+1) to the signal line S(m+1). Similarly, currents flow from the current sources C(i+1), C(i+3), C(i+4), C(i+5), and C(i+6) to the signal lines S(m+1), S(m+3), S(m+4), S(m+5), and S(m+6), respectively. Though not shown in FIG. 3 , the current source C(i+6) is the current source to the right of the current source C(i+5). This is referred to as Selection ( 2 ). [0069] Next, signals are inputted to the wires A(l+2) and A(l+2)b and an analog switch to be connected is chosen to turn it conductive. Then a current flows from the current source connected with the selected analog switch to a signal line, for example, from the current source C(i+1) to the signal line S(m). Similarly, currents flow from the current sources C(i+1), C(i+3), C(i+4), C(i+5), and C(i+6) to the signal lines S(m−1), S(m+1), S(m+2), S(m+3), and S(m+4), respectively. Though not shown in FIG. 3 , the signal line S(m−1) is the signal line to the left of the signal line S(m). This is referred to as Selection ( 3 ). [0070] Selections ( 1 ) to ( 3 ) are repeated at given intervals. In this way, an image displayed is made seemingly uniform even when the current inputted from the current sources C(i) to C(i+5) to the signal lines S(m) to S(m+5) is fluctuated. [0071] The switching period in the signal line driving circuit of the present invention is described with reference to a timing chart of FIG. 4 . F 1 to F 3 in FIG. 4 denote first to third frame periods, respectively, and it takes one frame period for a light emitting device to display one image. One frame period is usually set to about 1/60 second in order to prevent flicker from being recognized by the human eye. A(l) to A(l+2) and A(l)b to A(l+2)b in FIG. 4 represent electric potentials of signals inputted to the wires A(l) to A(l+2) and A(l)b to A(l+2)b. [0072] A switching period in which the electric potential of a signal inputted to A(l) is High (H) and the electric potential of a signal inputted to A(l)b is Low (L) is set in the first frame period F 1 . In this switching period, analog switches that are connected to the wires A(l) and A(l)b are turned conductive and currents are inputted from the transistors that are connected with the now-conductive analog switches to signal lines. Accordingly, only one analog switch out of each switching unit is turned conductive. [0073] A switching period in which the electric potential of a signal inputted to A(l+1) is High (H) and the electric potential of a signal inputted to A(l+1)b is Low (L) is set in the second frame period F 2 . In this switching period, analog switches that are connected to the wires A(l+1) and A(l+1)b are turned conductive, and currents are inputted from the transistors that are connected with the now-conductive analog switches to signal lines. [0074] A switching period in which the electric potential of a signal inputted to A(l+2) is High (H) and the electric potential of a signal inputted to A(l+2)b is Low (L) is set in the third frame period F 3 . In this switching period, analog switches that are connected to the wires A(l+2) and A(l+2)b are turned conductive and currents are inputted from the transistors that are connected with the now-conductive analog switches to signal lines. [0075] The frame periods F 1 to F 3 are repeated to allow the switching means to switch currents flowing into the signal lines S(m) to S(m+5) in order. [0076] The description given in this embodiment deals with a structure in which the power supply line connected to a current source having an n type transistor is Vss and a current flows from a pixel to Vss. However, the polarity of the transistor is set in accordance with the polarity of the pixel as mentioned above. Accordingly, if the circuit takes a structure in which a current flows toward a pixel, the power supply line is Vdd and the transistor of the current source is given the p type conductivity. [0077] Described next is a case in which a current source has a DA conversion function. This current source makes a current source circuit that outputs a current having analog values of 8 gray scales when a 3-bit digital video signal is inputted, for example. [0078] FIG. 5 shows a specific circuit structure of such a current source circuit. As shown in FIG. 5 , each current source has three transistors, Tr 1 ( i ), Tr 2 ( i ), and Tr 3 ( i ). The ratio of W (gate width)/L (gate length) of the three transistors Tr 1 ( i ), Tr 2 ( i ), and Tr 3 ( i ) is set to 1:2:4. Then, with the same gate voltage applied to the transistors Tr 1 ( i ), Tr 2 ( i ), and Tr 3 ( i ), the ratio of currents flowing in the transistors is 1:2:4. In short, the ratio of currents supplied from one current source is 1:2:4 and the amount of current can be controlled in 2 3 =8 stages. Accordingly, the current source circuit can output a current having analog values of 8 gray scales from a 3-bit digital video signal. [0079] Which of the transistors Tr 1 ( i ), Tr 2 ( i ), and Tr 3 ( i ) will be turned ON or OFF is controlled by controlling the voltage applied to their gates. This way the current value of currents outputted from the current sources C(i) to C(i+5) can be controlled. However, combinations of the currents from the current sources C(i) to C(i+5) and the signal lines S(m) to S(m+5) are varied by the switching means. Therefore voltages applied to the transistors Tr 1 ( i ), Tr 2 ( i ), and Tr 3 ( i ) of each of the current sources C(i) to C(i+5) have to be switched in accordance with a switch in combination. [0080] By giving a current source a DA conversion function as above, an image can be displayed in gray scales with high accuracy. The bit number can be set to suit individual cases and transistors are designed in accordance with the set bit number. [0081] In a light emitting device that uses the above-described signal line driving circuit of the present invention, display unevenness of pixels is reduced visually and the light emitting device can display a uniform image having no unevenness. The present invention can provide a uniform image with no display unevenness also when a signal is inputted through an external circuit to a signal line if the present invention is applied to the external circuit. [0082] Furthermore, the present invention makes it possible to reduce the size and weight of a light emitting device if semiconductor elements of its signal line driving circuit are polysilicon transistors. This is because polysilicon transistors can be used for semiconductor elements of a pixel portion thereof and accordingly the pixel portion and a peripheral circuit portion that includes the signal line driving circuit can be formed integrally on the same substrate. When a pixel portion and a peripheral circuit portion are integrally formed on the same substrate, no external circuit is necessary. Since complex processes for connecting an external circuit to signal lines and failed connection can be avoided, the reliability of the light emitting device is improved by the present invention. Embodiment 2 [0083] In the present invention, the number of current sources (columns of current sources) or the position of current sources (current source column number) may be asymmetric as long as one signal line is connected to 2 or more current sources. This embodiment shows as examples different structures for connection between switching units of switching means, signal lines, and current sources than Embodiment 1. [0084] FIG. 8 shows a structure in which current sources C(i) to C(i+5) are connected to signal lines S(m) to S(m+5) through switching means. Switching means of the present invention has a function of switching currents sent from current sources. In order to avoid complicating the drawing, the switching function is schematically illustrated in FIG. 8 to give only 3 terminals and switches. [0085] For instance, the signal line S(m+2) can be connected to any one of the current sources C(i+2), C(i+3), and C(i+4). In short, one signal line can be connected to the closest current source and 2 adjacent current sources to the right of the closest current source. This rule is used to connect the rest of the signal lines, S(m), S(m+1), S(m+3), S(m+4), and S(m+5) to the current sources. [0086] To generalize this connection using the function that expresses the present invention, the current sources are set so as to satisfy F 1 (N)=N+a, F 2 (N)=N+b, and F 3 (N)=N+c (a, b, and c are integers and a≠b≠c) when i=3, and a=−2, b=−1, and c=0. [0087] According to the connection relation between signal lines and current sources of the present invention, it is not always necessary to connect a signal line with the closest current source, namely, a current source in the closest column, but a signal line may be connected to a distant current source. A connection structure shown in FIG. 9 is given an example thereof. [0088] In FIG. 9 , current sources C(i) to C(i+6) are connected to signal lines S(m) to S(m+6) through switching means. This switching means too has 3 terminals and switches. [0089] For instance, the signal line S(m+2) can be connected to any one of the current sources C(i), C(i+2), and C(i+4). In short, one signal line can be connected to the closest current source and to the current source the second from the closest current source on each side. This rule is used to connect the rest of the signal lines, S(m), S(m+1), S(m+3), S(m+4), S(m+5), and S(m+6) to the current sources. [0090] To generalize this connection using the function that expresses the present invention, the current sources are set so as to satisfy F 1 (N)=N+a, F 2 (N)=N+b, and F 3 (N)=N+c (a, b, and c are integers and a≠b≠c) when i=3, and a=−2, b=0, and c=−2. [0091] According to the connection relation between signal lines and current sources of the present invention, the number of current sources connected to one signal line is not limited to 3. FIG. 10 shows an example of connecting 5 current sources in one switching unit. [0092] In FIG. 10 , current sources C(i) to C(i+6) are connected to signal lines S(m) to S(m+6) through switching means. A switching unit in this switching means has 5 terminals and switches. [0093] For instance, the signal line S(m+2) can be connected to any one of the current sources C(i), C(i+1), C(i+2), C(i+3), and C(i+4). In short, one signal line can be connected to the closest current source and to 2 adjacent current sources on each side. This rule is used to connect the rest of the signal lines, S(m), S(m+1), S(m+3), S(m+4), and S(m+5) to the current sources. [0094] To generalize this connection using the function that expresses the present invention, the current sources are set so as to satisfy F 1 (N)=N+a, F 2 (N)=N+b, F 3 (N)=N+c, F 4 (N)=N+d, F 5 (N)=N+c (a, b, c, d, and e are integers and a≠b≠c≠d≠e) when i=5, and a=−2, b=−1, c=0, d=1, and e=2. [0095] A displayed image seems more uniform and unevenness is reduced more as the number of current sources that can be connected to one signal line is larger as in FIG. 10 . [0096] In this embodiment, currents flowing into signal lines can be switched by the method described in Embodiment 1 which uses analog switches to switch current sources. This embodiment may also employ current sources that have a DA conversion function (see Embodiment 1 for details). In short, this embodiment can be combined with the switching means and current sources of Embodiment 1. [0097] As described above, the connection relation between signal lines and current sources of the present invention allows current sources to be in asymmetric number and position as long as one signal line is connected to 2 or more current sources and currents flowing into signal lines can be switched. Embodiment 3 [0098] This embodiment describes an example in which a light emitting device of the present invention displays an image in gray scales by dividing one frame period (a unit frame period associated with synchronization timing of a video signal inputted) into, sub-frame periods (this display method is called time ratio gray scale driving display). [0099] Time ratio gray scale driving display is explained first. In a time ratio gray scale driving method using a digital video signal (digital driving), a writing period Ta and a display period (also called a lighting period) Ts are alternately repeated in one frame period to display one image. [0100] For example, when an image is displayed from an n-bit digital video signal, one frame period has at least n writing periods and n display periods. The n writing periods are respectively associated with n bits of the video signal and the same applies to the n display periods. [0101] As shown in FIG. 11A , a writing period Tam (m is an arbitrary number ranging from 1 to n) is followed by a display period that is associated with the same bit number, in this case, a display period Tsm. One writing period Ta and one display period Ts constitute a sub-frame period SF. The sub-frame period consisting of the writing period Tam and the display period Tsm which are associated with the m-th bit is SFm. Lengths of the display periods Ts 1 to Tsn are set so as to satisfy Ts 1 :Ts 2 : . . . :Tsn=2 0 :2 1 : . . . :2 (n-1) . [0102] In each sub-frame period, whether or not a light emitting element emits light is decided based on the bit of the digital video signal. The sum of lengths of display periods in one frame period in which a light emitting element emits light is controlled to control the gray scale number. [0103] In order to improve the quality of an image displayed, a sub-frame period having a long display period may be divided into several periods. For a specific dividing method, see Japanese Patent Application No. 2000-267164. [0104] In this embodiment, it is desirable to switch currents flowing from current sources to signal lines in a display period of a sub-frame period. If the switch is made in a writing period, the inputted current, namely, information on whether or not a light emitting element is to emit light, may not be transferred successfully. By switching in such short a period at intervals, fluctuation in luminance of light emitting elements is further reduced and the uniformity in display is improved. [0105] FIG. 11B shows a specific example in which a 3-bit signal is used. In FIG. 11B , one frame period has sub-frame periods SF 1 , SF 2 , and SF 3 . The sub-frame periods SF 1 , SF 2 , and SF 3 have writing periods Ta 1 , Ta 2 , and Ta 3 and display periods Ts 1 , Ts 2 , and Ts 3 , respectively. Periods in which connection between a signal line and a current source is switched (hereinafter simply referred to as switching periods) 1 , 2 , and 3 are provided in display periods Ts 1 , Ts 2 , and Ts 3 , respectively. Currents inputted from current sources to signal lines are switched in the switching periods 1 to 3 . In this way, the switch can be made in a short period at intervals and a displayed image seems more uniform. [0106] The switching periods 1 to 3 in FIG. 11B are each put immediately before a writing period. However, a switching period can be set in any time frame as long as it is within a display period. [0107] FIG. 11C is a timing chart of signals inputted to analog switches. In the first frame, A 1 is ON in SF 1 , A 2 is ON in SF 2 , and A 3 is ON in SF 3 . In the second frame, A 2 is ON in SF 1 , A 3 is ON in SF 2 , and A 1 is ON in SF 3 . Though not shown in FIG. 11C , it is similar for the third frame and A 3 is ON in SF 1 , A 1 is ON in SF 2 , and A 2 is ON in SF 3 . [0108] If ON states of A 1 to A 3 in the sub-frame periods SF 1 to SF 3 are fixed (if A 1 is ON in SF 1 , A 2 is ON in SF 2 , and A 3 is ON in SF 3 throughout the first to third frames), fluctuation cannot be evened out sufficiently. Accordingly, as shown in FIG. 11C , it is desirable to vary their ON states from one sub-frame period to another and from one frame period to another. [0109] This embodiment is merely an example and which signal is inputted in which sub-frame period can be set to suit individual cases. For a specific method of inputting signals, see FIG. 4 . [0110] In this embodiment, it is preferable to employ the current source circuits of Embodiment 1 which have a DA conversion function in order to raise the gray scale number. This embodiment can be combined with Embodiments 1 and 2. Embodiment 4 [0111] This embodiment describes the structure of a light emitting device of the present invention with reference to FIG. 12 . [0112] The light emitting device of the invention includes a pixel portion 402 having a plurality of pixels arranged in matrix on a substrate 401 , and includes a signal line driving circuit 1203 , a first scanning line driver circuit 404 and a second scanning line driver circuit 405 in the periphery of the pixel portion 402 . Although the signal line driving circuit 1203 and the two scanning line driver circuits 404 and 405 are provided in FIG. 12(A) , the present invention is not limited thereto, and may be arbitrarily designed depending on the pixel structure. Signals are supplied from the outside to the signal line driving circuit 1203 , the first scanning line driver circuit 404 and the second scanning line driver circuit 405 via FPCs 406 . [0113] The structures and operations of the first scanning line driver 404 circuit and the second scanning line driver circuit 405 will be described using FIG. 12(B) . The first scanning line driver 404 circuit and the second scanning line driver circuit 405 each include a shift register 407 and a buffer 408 . Operations will be briefly described as: the shift register 407 sequentially outputs sampling pulses in accordance with a clock signal (G-CLK), a start pulse (S-SP), and an inverted clock signal (G-CLKb); thereafter, the sampling pulses amplified in the buffer 408 are input to scanning lines; and the scanning lines are set to be in a selected state for each line; signal currents I data are sequentially written to pixels controlled by the selected signal lines. [0114] Note that the structure may be such that a level shifter circuit is arranged between the shift register 407 and the buffer 408 . Disposition of the level shifter circuit enables the voltage amplitude to be increased. [0115] The structure of the signal line driving circuit 1203 will be hereafter described. Note that this embodiment may be arbitrarily combined with Embodiment 1, 2 and 3. [0116] Current sources provided in the signal line driving circuit of the invention may not be arranged in a straight line, but may be shifted and arranged. Further, two signal line driving circuits may be provided symmetrical to the pixel portion. That is to say, the present invention does not limit the arrangement of the current sources as long as the current sources connect to the signal lines via switching means. Embodiment 5 [0117] In this embodiment, the detailed structure and operations of the signal line driving circuit 1203 used in the case of performing 1-bit digital gradation display will be described with reference to FIG. 13 . [0118] FIG. 13(A) is a schematic view of the signal line driving circuit 1203 used in the case of performing 1-bit digital gradation display. The signal line driving circuit 1203 includes a shift register 1211 , a first latch circuit 1212 , a second latch circuit 1213 and a constant current circuit 1214 . The shift register 1211 , the first latch circuit 1212 and the second latch circuit 1213 function as switches used for the video signals shown in FIG. 1 . [0119] Further, the constant current circuit 1214 is constituted by a plurality of current sources. FIG. 13(B) shows specific circuits of the shift register 1211 , the first latch circuit 1212 and the second latch circuit 1213 . [0120] Operations will be briefly described. The shift register 1211 is constituted by, for example, a plurality of flip-flop circuits (FFs). A clock signal (S-CLK), a start pulse (S-SP) and an inverted clock signal (S-CLKb) are input therein, and sampling pulses are sequentially output in accordance with the timing of these signals. [0121] The sampling pulses, which have been output from the shift register 1211 , are input to the first latch circuit 1212 . Digital video signals have been input to the first latch circuit 1212 , and a video signal is retained in each column in accordance with the input timing of the sampling pulse. [0122] In the first latch circuit 1212 , upon completion of video-signal retaining operations in columns to the last column, during a horizontal return period, a latch pulse is input to the second latch circuit 1213 , and video signals retained in the first latch circuit 1212 are transferred in batch to the second latch circuit 1213 . As a result, one-line video signals retained in the second latch circuit 1213 are input to video switches at the same time. On-off operations of the video switches are carried out to control the input of the signals to the pixels, thereby displaying the gradation. [0123] While the video signals retained in the second latch circuit 1213 are being supplied to the constant current circuit 1214 , sampling pulses are again output in the shift register 1211 . Thereafter, the operation is iterated, and one-frame video signals are processed. [0124] In addition, Embodiment 5 can be arbitrarily combined with the inventions described in embodiments 1, 2, 3 and 4. Embodiment 6 [0125] Electronic equipment using the light emitting device of the present invention includes, for example, video cameras, digital cameras, goggle type displays (head mount displays), navigation systems, audio reproducing devices (such as car audio and audio components), notebook personal computers, game machines, mobile information terminals (such as mobile computers, mobile phones, portable game machines, and electronic books), and image reproducing devices provided with a recording medium (specifically, devices for reproducing a recording medium such as a digital versatile disc (DVD), which includes a display capable of displaying images). In particular, in the case of mobile information terminals, since the degree of the view angle is appreciated important, the terminals preferably use the light emitting device. Practical examples are shown in FIG. 15 . [0126] FIG. 15(A) shows a light emitting device, which contains a casing 2001 , a support base 2002 , a display portion 2003 , a speaker portion 2004 , a video input terminal 2005 , and the like. The light emitting device of the present invention can be applied to the display portion 2003 . Further, the light emitting device shown in FIG. 15(A) is completed with the present invention. Since the light emitting device is of self-light emitting type, it does not need a back light, and therefore a display portion that is thinner than that of a liquid crystal display can be obtained. Note that light emitting devices include all information display devices, for example, personal computers, television broadcast transmitter-receivers, and advertisement displays. [0127] FIG. 15(B) shows a digital still camera, which contains a main body 2101 , a display portion 2102 , an image receiving portion 2103 , operation keys 2104 , an external connection port 2105 , a shutter 2106 , and the like. The light emitting device of the present invention can be applied to the display portion 2102 . Further, the digital still camera shown in FIG. 15 (B) is completed with the present invention. [0128] FIG. 15(C) shows a notebook personal computer, which contains a main body 2201 , a casing 2202 , a display portion 2203 , a keyboard 2204 , external connection ports 2205 , a pointing mouse 2206 , and the like. The light emitting device of the present invention can be applied to the display portion 2203 . Further, the light emitting device shown in FIG. 15(C) is completed with the present invention. [0129] FIG. 15(D) shows a mobile computer, which contains a main body 2301 , a display portion 2302 , a switch 2303 , operation keys 2304 , an infrared port 2305 , and the like. The light emitting device of the present invention can be applied to the display portion 2303 . Further, the mobile computer shown in FIG. 15(D) is completed with the present invention. [0130] FIG. 15(E) shows a portable image reproducing device provided with a recording medium (specifically, a DVD reproducing device), which contains a main body 2401 , a casing 2402 , a display portion A 2403 , a display portion B 2404 , a recording medium (such as a DVD) read-in portion 2405 , operation keys 2406 , a speaker portion 2407 , and the like. The display portion A 2403 mainly displays image information, and the display portion B 2404 mainly displays character information. The light emitting device of the present invention can be used in the display portion A 2403 and in the display portion B 2404 . Note that family game machines and the like are included in the image reproducing devices provided with a recording medium. Further, the DVD reproducing device shown in FIG. 15(E) is completed with the present invention. [0131] FIG. 15(F) shows a goggle type display (head mounted display), which contains a main body 2501 , a display portion 2502 , an arm portion 2503 , and the like. The light emitting device of the present invention can be used in the display portion 2502 . The goggle type display shown in FIG. 15(F) is completed with the present invention. [0132] FIG. 15(G) shows a video camera, which contains a main body 2601 , a display portion 2602 , a casing 2603 , external connection ports 2604 , a remote control reception portion 2605 , an image receiving portion 2606 , a battery 2607 , an audio input portion 2608 , operation keys 2609 , an eyepiece portion 2610 , and the like. The light emitting device of the present invention can be used in the display portion 2602 . The video camera shown in FIG. 15(G) is completed with the present invention. [0133] Here, FIG. 15(H) shows a mobile phone, which contains a main body 2701 , a casing 2702 , a display portion 2703 , an audio input portion 2704 , an audio output portion 2705 , operation keys 2706 , external connection ports 2707 , an antenna 2708 , and the like. The light emitting device of the present invention can be used in the display portion 2703 . Note that, by displaying white characters on a black background, the current consumption of the mobile phone can be suppressed. Further, the mobile phone shown in FIG. 15(H) is completed with the present invention. [0134] When the emission luminance of light emitting materials are increased in the future, the light emitting device will be able to be applied to a front or rear type projector by expanding and projecting light containing image information having been output lenses or the like. [0135] Cases are increasing in which the above-described electronic equipment displays information distributed via electronic communication lines such as the Internet and CATVs (cable TVs). Particularly increased are cases where moving picture information is displayed. Since the response speed of the light emitting materials is very high, the light emitting device is preferably used for moving picture display. [0136] Since the light emitting device consumes power in a light emitting portion, information is desirably displayed so that the light emitting portions are reduced as much as possible. Thus, in the case where the light emitting device is used for a display portion of a mobile information terminal, particularly, a mobile phone, an audio playback device, or the like, which primarily displays character information, it is preferable that the character information be formed in the light emitting portions with the non-light emitting portions being used as the background. [0137] As described above, the application range of the present invention is very wide, so that the invention can be used for electronic equipment in all of fields. The electronic equipment according to this embodiment may use the structure of the signal line driving circuit according to any one of Embodiments 1 to 5. [0138] The present invention can provide a semiconductor integrated circuit in which influence of characteristic fluctuation between transistors in a current source circuit is reduced until the transistor characteristics do not affect the circuit, and a method of driving the semiconductor integrated circuit. The semiconductor integrated circuit of the present invention can be used in a driving circuit portion to provide a light emitting device having a pixel portion. In particular, the semiconductor integrated circuit of the present invention can be applied to a signal line driving circuit of a driving circuit portion to provide an active matrix light emitting device in which pixels are arranged so as to form a matrix pattern and each of the pixels has a switching element and a light emitting element. The present invention can also provide a light emitting device in which elements of a pixel portion and a driving circuit portion are polysilicon thin film transistors to integrally form the pixel portion and the driving circuit portion on the same substrate.

A transistor causes fluctuation in the threshold and mobility due to the factor such as fluctuation of the gate length, the gate width, and the gate insulating film thickness generated by the difference of the manufacturing steps and the substrate to be used. As a result, there is caused fluctuation in the current value supplied to the pixel due to the influence of the characteristic fluctuation of the transistor, resulting in generating streaks in the display image. A light emitting device is provided which reduces influence of characteristics of transistors in a current source circuit constituting a signal line driving circuit until the transistor characteristics do not affect the device and which can display a clear image with no irregularities. A signal line driving circuit of the present invention can prevent streaks in a displayed image and uneven luminance. Also, the present invention makes it possible to form elements of a pixel portion and driving circuit portion from polysilicon on the same substrate integrally. In this way, a display device with reduced size and current consumption is provided as well as electronic equipment using the display device.

FIELD OF INVENTION [0001] This invention relates to a method of analyzing cellular chromosomes, and particularly relates to a method of analyzing the chromosomes of amniotic cells by sequencing. BACKGROUND OF INVENTION Fetal Chromosomal Aneuploidy [0002] Fetal chromosomal aneuploidy means a condition that the number of chromosome is not diplontic in a fetal genome. Normally, there are 44 autosomes and 2 sex chromosomes in a human genome in which the male karyotype is (46, XY) and the female karyotype is (46, XX). Fetal chromosomal aneuploidy may refer to the condition of having one more chromosome than a normal diploid fetus, i.e. 47 chromosomes in the fetal genome. Take fetal trisomy 21 for example, compared with a normal diploid fetus, the fetus with trisomy has an extra chromosome 21 with the karyotype of 47, XX (or XY), +21. Also, fetal chromosomal aneuploidy refers to the condition of missing a chromosome in comparison with the normal diploid fetus, i.e. 45 chromosomes in the fetal genome. For example, the fetus with Turner syndrome with the karyotype of 45, XO misses one chromosome, relative to the normal diploid fetus. Fetal chromosomal aneuploidy also refers to the condition that a part of chromosome is lost, or example, translocated trisomy 21 with the karyotype of 45, XX, der (14; 21)(q10; q10), and Cri du chat syndrome with the karyotype of 46, XX (XY),del (5)(p13). [0003] According to incomplete statistics, the birth rate of fetuses with chromosomal aneuploidy is 1/160 in the world, wherein the birth rate of fetal trisomy 21 (T21, Down syndrome) is 1/800, the birth rate of fetal trisomy 18 (T18, Edwards syndrome) is 1/6000, and the birth rate of trisomy 13 (T13, Patau syndrome) is 1/10000. The development of fetuses with other types of the chromosomal aneuploidy stagnates because some developmental stages could not be accomplished, resulting in clinically unreasoned miscarriage at the early stage of gestation (Deborah A. Driscoll, M. D., and Susan Gross, M. D., Prenatal Screening for Aneuploidy[J] . N Engl J Med 2009; 360:2556-62). Current Situation of Culturing Amniotic Cells [0004] Amniotic cells are epithelial cells floating in the amniotic fluid, which derive from skin, digestive tracts and respiratory tracts of fetus. The procedure of culturing amniotic cells, enriching the number of fetal nucleated cells, preparing chromosomal specimen, and analyzing the fetal chromosomal karyotype is a golden standard of traditionally clinically diagnosing the chromosomal abnormality of fetuses. This technique is reliable, accurate, and enables the observation of abnormalities of chromosome number and structure. Its disadvantages, however, are that it is time-consuming, it takes 10 days to 3 weeks to yield the result, and culturing failure rate is about 1.00% (THEIN A T, ABDEL-FATTAH S A, KYLE P M, et al., An Assessment of the Ase of Interphase FISH with Chromosome Specific Probes as an Alternative to Cytogenetics in Prenatal Diagnosis [J] . PrenatDiagn, 2000, 20(4): 275-280). [0005] The reason of high failure rate of culturing amniotic cells is that the amniotic cells are aging and pyknotic cells, resulting in harder culturing than that of the other tissues (Changjun Ma, Yuania Chen, Peidan Huo; The Culture of Amniotic Cells and the Method of Preparing the Chromosomal Specimen Thereof [J]. Reproduction and Contraception, 1985, 5 (1): 53-4). Therefore, successful culturing of amniotic cells plays a critical role in the process of detecting chromosomal aneuploidy. Because of the high requirement of culturing amniotic cells, relatively few viable cells in the amniotic fluid of some of pregnant women, relatively few harvested cells with division phases, and poor chromosomal shape, it is difficult to count and analyze a sufficient number of cells, and detect chromosomes. Furthermore, amniocentesis is a risk with about 2-3% of pregnant women suffering complications, such as uterine contractions, abdominal swelling, tenderness, vaginal bleeding, infection, water leakage, or fetal injury. It would be unacceptable for a pregnant woman if being asked to do second amniocentesis if the culturing of amniotic cells fails or the harvested cells are not sufficient to count and analyze. Moreover, the amniocentesis is generally performed at 16-20 weeks' gestation, once the culture fails, many pregnant women's gestational period has advanced too far, and thus have to undergo cordocentesis with even higher risk. After the culturing of amniotic cells, the analysis of karyotype requires a lot of labor and costs such that many hospitals cannot afford the procedure, causing great difficulties in the clinical spreading and application of amniocentesis. [0006] With the continuous development of sequencing techniques, it is being increasingly applied in the detection and analysis of the chromosome number. Dennis Lo et al. used the peripheral blood of a pregnant woman as experimental material to examine the abnormality of chromosome number by means of massive sequencing based on mathematical statistics methods (Y. M. Dennis Lo, et al., Quantitative Analysis of Fetal DNA in Maternal Plasma and Serum: Implications for Noninvasive Prenatal Diagnosis . Am. J. Hum. Genet. 62:768-775, 1998). But this method cannot completely replace amniocentesis in clinical application, because of some defects occurring in the technique: the cell-free DNAs in plasma are fragmented DNAs, they cannot form a complete genome on their own, the aneuploidy, translocation or mosaicism of the chromosomes other than chromosomes 21, 18, and 13 fails to be detected or have a low detective accuracy. SUMMARY OF INVENTION [0007] In order to overcome the missed results of detection caused by the sequencing of peripheral blood, and resolve the high failure rate of the culturing of amniotic cells, this invention, in combination with the advantages of the analysis of karyotype by amniocentesis and the method of sequencing the cell-free DNAs in plasma, utilizes a method of detecting chromosomal aneuploidy based on massive sequencing of amniotic cells, including the steps of drawing amniotic cells, isolating DNA, conducting high-throughout sequencing, analyzing the obtained data, and acquiring detection results. [0008] In one aspect of the invention, a method of using high-throughout sequencing technique to analyze the chromosomal information of a subject's cells is provided, comprising the steps of: [0009] a. randomly breaking the genomic DNA of the cells, obtaining DNA fragments with a certain size, and sequencing them; [0010] b. strictly aligning the DNA sequences sequenced in step a to the reference sequence of the human genome to obtain the information about the DNA sequences located on a particular chromosome; [0011] c. for the particular chromosome N, determining the total number of the sequences mapped to a sole region of the chromosome, among the above-sequenced DNA sequences, thereby making ChrN % for chromosome N, i.e. ratio of the total number (S1) of the sequences mapped to the sole place of chromosome N, among the above-sequenced DNA sequences, to the total number (S2) of the sequences located on all chromosomes, among the above-sequenced DNA sequences: ChrN %=S1/S2; [0012] d. comparing ChrN % for chromosome N with ChrN % for the corresponding chromosome coming from standard cells to determine whether there exists a difference between the chromosome of the cells and the corresponding one of the standard cells. [0013] In the invention, the cells may be, for example, amniotic cells, wherein the amniotic cells may be uncultured amniotic cells or cultured amniotic cells. In one embodiment of the invention, to avoid culturing amniotic cells, the amniotic cells are uncultured amniotic cells. [0014] In the invention, the genomic DNA of the cells may be obtained by traditional methods of isolating DNA, such as salting-out, column chromatography, and SDS, preferably by column chromatography. The so-called column chromatography involves using cell lysis buffer and protease K to treat amniotic cells or tissues to expose naked DNA molecules, making them pass through a silica membrane column capable of binding negatively charged DNA molecules, to which the genomic DNA molecules in the system are reversibly adsorbed, removing the impurities such as proteins or lipids by washing buffers, and diluting by purifying buffers to obtain the DNA of amniotic cells (for more details about specific principles and methods, see the product manuals for product No. 56304 from Qiagen and product DP316 from Tiangen). [0015] In the invention, the DNA molecules are randomly broken by restriction cleavage, atomization, ultrasound, or HydroShear method. HydroShear method is preferably used (when the solution containing DNA is flowing through a passage with small section, the flowing rate is accelerated, creating a force enough to destruct suddenly the DNA to produce DNA fragments in various sizes depending on the flowing rate and the section area. For more details about specific principles and methods, see product manuals of HydroShear from Life Sciences Wild). In this way the DNA molecules are broken into fragments with a narrow range of sizes, of which major bands generally range from 200 bp to 300 bp in size. [0016] The sequencing method adopted in the invention may be the second generation sequencing method such as Illumina/Solexa or ABI/SOLiD. In one embodiment of the invention, the sequencing method is Illumina/Solexa and the resultant sequences are fragments with 35 bp in size. [0017] When the DNA molecules to be examined are from multiple samples, each sample may be attached a different tagged sequence index so as to be processed during the process of sequencing (Micah Hamady, Jeffrey J Walker, J Kirk Harris et al., Error - correcting Barcoded Primers for Pyrosequencing Hundreds of Samples in Multiplex . Nature Methods, 2008, March, Vol. 5 No. 3). [0018] In the invention, the reference sequence of the human genome is produced after the shield of the repeated sequences within the human genome sequence, for example, the latest version of the reference sequence of the human genome in the NCBI database. In one embodiment of the invention, the human genome sequence is the reference sequence of the human genome as shown in version 36 (NCBI Build 36) of NCBI database. [0019] In the invention, aligning strictly with the reference sequence of the human genome means that the adopted method of alignment is a fault-intolerant alignment of the sole region located in the reference sequence of the human genome. In one embodiment of the invention, alignment software Eland (a software package provided by Illumina) was used, and the method adopted was an absolute, fault-intolerance alignment. [0020] In the invention, when the said DNA sequences is a sequence which is able to be located at a sole region of the reference sequence of the human genome, it is defined as sole sequence represented by Unique reads. In the invention, for the purpose of avoiding the interference of the repeated sequences, it is needed to remove those DNA sequences located at the regions of tandem repeats and transpositional repeats within the reference sequence of the human genome and merely take into account those DNA sequences, i.e. sole sequences, which may be located at a sole region. Generally, of all the sequenced DNA sequences, about a quarter to a third of DNA sequence are able to be located at a sole region of the genome, i.e. sole sequences. The statistical number of these sole sequences represents the distribution of the DNA sequences on the genomic chromosomes. [0021] Therefore, the sole sequences can assist in the localization of each DNA sequence that is produced by breaking and sequencing the DNA molecules isolated from amniotic cells on a particular chromosome. ChrN % is values produced by normalizing the sole sequences found on different chromosomes, and the values are merely relevant to the size of a particular chromosome rather than the amount of the data being sequenced. Thus the values can be used to analyze the information on individual 46 chromosomes. Therefore, ChrN % is basic value to conduct a chromosomal analysis. [0022] In the invention, whether there exists a difference between the number of a particular chromosome in the cellular samples and the standard cells can be determined by drawing a boxplot, wherein a sample for which ChrN % corresponds to an outlier that goes beyond 1.5-3 time or above 3 times the interquartile range is determined to differ from the standard cells in the chromosome number, i.e. aneuploidy. [0023] In the invention, determining whether there exists a difference between a particular chromosome respectively in the said cellular samples and in the standard cellular samples may be accomplished by using “z score_ChrN” to indicate the deviation of ChrN % for the said cellular samples from ChrN % for the standard cellular samples. [0024] Specifically, z score_ChrN=(ChrN % for a particular chromosome from detection samples−ChrN % mean (mean_ChrN %) for the particular chromosome)/ChrN % standard deviation (S.D._ChrN %). [0025] If z score_ChrN is extremely large or small, it means that the deviation of the chromosome number in the cellular detection sample from that of the normal sample is significant. When it reaches a given level of significance, it may be believed that there is an apparent difference between the former number and the latter number. [0026] In the invention, the average value of ChrN % for a particular chromosome from the standard cellular samples may be determined according to ChrN % for the chromosome from such as at least 10, 20, 30, 50, or 100 standard cellular samples. [0027] In the invention, the standard cellular samples are the samples of human cells in which the number of the chromosomes is diploid. A normal male cell has 44 autosomes and 2 different sex chromosomes, (46, XY). On the other hand, a normal female cell has 44 autosomes and 2 identical sex chromosomes, (46, XX). [0028] In the invention, the ChrN % standard deviation (S.D._ChrN %) for a particular chromosome from the standard cellular samples may be determined according to the ChrN % for the chromosomes, such as at least 10, 20, 30, 50, or 100 standard cellular samples. [0029] In one embodiment of the invention, the standard cellular samples have 20 samples from normal males and 10 samples from normal females, numbered, respectively, with 1, 2, . . . , 30, in which Nos. 1-20 are the detection samples from normal males, Nos. 21-30 are the detection samples from normal females. The average value of ChrN % (mean_ChrN %) for the standard cellular samples is calculated as follows: [0000] Mean_ChrN  % = 1 30  ∑ m = 1 30  ChrC_M ) ( wherein   N   represents   autosomes   1  -  22 ,  M   represents   normal   samples   Nos .  1  -  30 ) Mean_ChrX  %   ( male ) = 1 20  ∑ m = 1 20  ChrX_M ( M   represents   normal   male   samples   Nos .  1  -  20 ) Mean_ChrY  %   ( male ) = 1 20  ∑ m = 1 20  ChrY_M ( M   represents   normal   male   samples   Nos .  1  -  20 ) Mean_ChrX  %   ( female ) = 1 10  ∑ m = 21 30  ChrX_M ( M   represents   normal   female   samples   Nos .  21  -  30 ) Mean_ChrY  %   ( female ) = 1 10  ∑ m = 21 30  ChrY_M ( M   represents   normal   female   samples   Nos .  21  -  30 ) [0030] (Note: due to the fluctuation of sequencing and a large number of gaps existing on Y chromosome of the reference sequence, it results in that even for the normal female samples there are a few DNA sequences aligned with Y chromosome. As compared with males, however, the ChrN % for females is much less than that for males. In the examples, the ChrN % for females is around 0.004, whereas the ChrN % for males is around 0.114.) [0031] Based on each ChrN % mean (mean_ChrN %) for the standard cellular samples obtained by the method described above, the ChrN % standard deviation (S.D._ChrN %) is calculated with the following formula: [0000] S . D . _ChrN  % = 1 30  ∑ m = 1 30  ( ChrN_M - mean_ChrN ) 2 ( wherin   N   represents   autosomes   1  -  22 ) S . D . _ChrX  %   ( male ) = 1 20  ∑ m = 1 20  ( ChrX_M - mean_ChrX ) 2 ( M   represents   normal   male   samples   Nos .  1  -  20 ) S . D . _ChrY  %   ( male ) = 1 20  ∑ m = 1 20  ( ChrX_M - mean_ChrX ) 2 ( M   represents   normal   male   samples   Nos .  1  -  20 ) S . D . _ChrX  %   ( female ) = 1 20  ∑ m = 1 20  ( ChrX_M - mean_ChrX ) 2 ( M   represents   normal   female   samples   Nos .  21  -  30 ) S . D . _ChrY  %   ( female ) = 1 20  ∑ m = 1 20  ( ChrX_M - mean_ChrX ) 2 ( M   represents   normal   female   samples   Nos .  21  -  30 ) [0032] Since there is a missed X chromosome replaced by Y chromosome among male chromosomes in contrast to female chromosomes, and the whole length of the X chromosome is about 155M, whereas the Y chromosome is about 59M. In detecting these sex chromosomes, it is necessary to establish a set of normal distribution curves concerning ChrX % or ChrY % for different agendas. The most accurate analysis for X chromosome can be obtained from the different agenda-based normal distribution curves. [0033] In one embodiment of the invention, 30 standard cellular samples were selected to conduct the chromosomal analysis. Then a normal distribution curve was established under the requirement of significance level (such as 0.1%) for normal distribution reached in the instance of having a difference between the number of simulated chromosomes and that in standard cells. Thus, the instance of the absolute value of the z score_ChrN being determined to be below 3 was defined by the number of chromosomes being the same as that in the standard cells. On the basis of the results above, then the chromosomes of the detection samples were analyzed as follows: [0034] If the absolute value of the z score amounts to 3, then the samples have a 99.9% probability that they are not among the normally distributed population, i.e. outliers. This means that the chromosome number of the detected cells differs from that of the standard cells, i.e. chromosomal aneuploidy. [0035] If the absolute value of the z score is less than 3, then the samples have a 99.9% probability that they are normal samples, which means that the chromosome number of the detected cells is the same as that of the standard cells. [0036] If the absolute value of the z score is greater than 3, then the samples have a 99.9% probability that they are abnormal samples, which means that the chromosome number of the detected cells differs from that of the standard cells, i.e. chromosomal aneuploidy. [0037] Further, in the invention, if the absolute value of the z score is greater than 3, for the specific instance of chromosomal aneuploidy occurring in the detected cells, the Z reference value (cutoff value) may be used to determine it. The Z reference value is calculated with the following formula: [0000] Z =(mean_ChrN %×0.5× X %)/S.D._ChrN % [0038] When N represents autosomes, mean_ChrN % and S.D._ChrN % are the means for all of the samples of the standard cells. When N represents sex chromosomes, mean_ChrN % and S.D._ChrN % are the means for the samples of the standard cells of respective agenda; [0039] X may be any integer between, inclusive, −100 and 100, such as −100, −90, −80, −70, −60, −50, −40, −30, −20, −10, 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100. [0040] In one embodiment of the invention, when X amounts to 100, it represents that the cellular detection samples have one more chromosome than the standard cells. In one embodiment of the invention, when X amounts to −100, it represents that the cellular detection samples have one less chromosome than the standard cells. When X amounts to 50, it represents that the cellular detection samples have extra half of one chromosome than the standard cells. In one embodiment of the invention, when X amounts to 50, it represents that the cellular detection samples lacks half of one chromosome in comparison with the standard cells. [0041] In the invention, in calculating the Z reference value for sex chromosomes, mean_ChrN % and S.D._ChrN % are calculated for either female samples or the male samples. That is: [0042] For the male samples, the Z reference value reached may be (mean_ChrN % (male)×0.5×X %)/S.D._ChrN % (male); [0043] For the female samples, Z reference value reached may be (mean_ChrN % (female)×0.5×X %)/S.D._ChrN % (female). [0044] When the absolute value of the z score_ChrN is greater than or equal to 3 and reaches the absolute value of the Z reference value, there is a significant difference between the number of a particular chromosome in the detected cells and that in the standard cells equal to X %. For example, when X amounts to 50, it represents that the detected cells have extra half of the particular chromosome compared with the standard cells; when X amounts to 100, it represents that the detected cells have one particular chromosome more than the standard cells. [0045] In one embodiment of the invention, the specific method of analyzing the chromosomes of amniotic cells includes the following steps: 1. DNA Isolation and Sequencing [0046] A library was built according to the modified Illumina/Solexa standard procedure of building a library after the DNA of amniotic cells was isolated in accordance with the manual from Tiangen Micro Kit. Then adapters for sequencing were added to the both ends of the randomly broken DNA fragments. During the process, a different tagged sequence (index) was attached to each of the samples such that multiple samples could be differentiated in the data obtained from one-time sequencing. 2. Alignment and Statistic [0047] After sequencing by using the second generation sequencing technique, known as Illumina/Solexa sequencing (other alternate sequencing methods can also be used to achieve the same or similar effects), the fragmented DNA sequences of a specified size were produced for each sample, which were subjected to alignment strictly with the reference sequence of the human genome. Thus, the information was obtained on the location of the sequences at the corresponding regions of the genome. [0048] Such a restricted alignment was required because it could not be determined from which chromosome a given DNA sequence originated if fault-tolerant alignment or the alignment with multiple regions was allowed. This would be unfavorable for the subsequent analysis of the data. [0049] The total number of the sole sequences located on each chromosome was calculated by taking each chromosome as a unit, thereby making the ChrN % for each chromosome, i.e. ratio of the total number (S1) of the sequences among the above-sequenced DNA sequences, which are located at the sole place of chromosome N, to the total number (S2) of the sequences among the above-sequenced DNA sequences, which are located on all chromosomes: ChrN %=S1/S2. [0050] This is a method of normalization for different samples having a different sequencing amount. Because amniotic cells contain the whole information of 46 chromosomes, theoretically the total number of the sequences located on a given chromosome is directly proportional to the length of the chromosome. [0051] For example, chromosome 1 is the largest chromosome (about 247 M) in the human genome, whereas chromosome 21 is the smallest chromosome (about 47 M) in the human genome, therefore, given a certain total amount of sequencing, the sequencing results from normal diploid amniotic cells are nearly a fixed value. Although in some sequencing and experimental conditions, the ChrN % is not directly proportional to the size of chromosomes, it is usually a fixed value. 3. Analysis of the Data [0052] By a boxplot boxplotanalysis, it may be directly determined whether the cellular detection samples are likely to differ from the standard cells in the chromosome number. The samples with abnormal values are directly considered as suspect samples, and the others are considered as standard cellular samples. The detailed process is as follows: [0053] In the invention, in order to help with the data analysis, a boxplot (used for differentiate abnormal values in mathematical statistics) involving the ChrN % produced above is adopted to determine suspect samples. The specific drawing process is as follows: [0054] 1) calculating the upper-quartile (75%), median (50%), and lower-quartile (25%); [0055] 2) calculating the difference, interquartile range (IQR), between the upper-quartile and lower-quartile; [0056] 3) drawing the upper and lower ranges of a boxplot with the upper limit being the upper-quartile and the lower limit being the lower-quartile, and drawing a horizontal line where the median lies inside the box; [0057] 4) values which are 1.5 times greater than the upper-quartile of the interquartile range or 1.5 times less than the lower-quartile of the interquartile range are classified as outliers. [0058] 5) beyond the outliers, drawing a horizontal line across the two value points closest to the upper margin and the lower margin, respectively, as a “whisker” of the boxplot. [0059] 6) extreme outliers going beyond a distance three times longer than the interquartile range are represented with star points; milder outliers that lie within 1.5-3 times as the distance of the interquartile are represented with hollow points. [0060] The bold line in the middle of the box represents median values, and the upper and lower boarders represent the upper and lower quartiles, respectively. Outliers are defined by the points deviating from 1.5 times the distance between the upper quartile and lower quartile. For example, when the detection samples are standard cellular samples, the ChrN % corresponding to their chromosomes is a fixed value (for example, 1). When the ChrN % corresponding to their chromosomes is 1.5, then the difference can be considered greatly significant, thereby making the samples suspected samples. That is, it is likely that they are samples differed from the standard cells in the chromosome number. [0061] If needed, the ChrN % mean and standard deviation (S.D._ChrN %) may be determined, respectively, by the ChrN % for a particular chromosome corresponding to the standard cellular samples. Then the z score_ChrN for the chromosome from the suspected samples are calculated with the following formula: [0000] z score_ChrN=(ChrN % for the particular chromosome from the suspected samples−ChrN % mean)/S.D._ChrN % [0062] If the absolute value of the z score_ChrN is greater than or equal to 3, there is a difference between the number of a particular chromosome in the cellular samples and that in the standard cells. [0063] Further, in the invention, for the specific instance of an abnormal chromosome number occurring in the cells, reference to the Z reference value (cutoff value) may be used to determine it. Value Z is calculated with the following formula: [0000] Z =(mean_ChrN %×0.5 ×X %)/S.D._ChrN % [0064] When N represents autosomes, the mean_ChrN % and S.D._ChrN % are the mean of all the samples of the standard cells. When N represents sex chromosomes, the mean_ChrN % and S.D._ChrN % are the mean of the samples of the standard cells of the respective agenda; [0065] X is assigned to be 50 or 100. Correspondingly, when X is 100, it represents that the cellular detection samples have one more chromosome than the standard cells. When X is 50, it represents that the cellular detection samples have extra half of one chromosome than the standard cells. [0066] In the invention, in calculating the Z reference value for sex chromosomes, the mean_ChrN % and S.D._ChrN % are the mean for either female samples and male samples, that is: [0067] For the male samples, the Z reference value reached is (mean_ChrN % (male)×0.5×X %)/S.D._ChrN % (male); [0068] For the female samples, the Z reference value reached is (mean_ChrN % (female)×0.5×X %)/S.D._ChrN % (female). [0069] When the absolute value of the z score_ChrN is greater than or equal to 3 and reaches the absolute value of the Z reference value, there is a X % difference between the number of a particular chromosome in the cells and that in the standard cells. ADVANTAGES OF THE INVENTION [0070] The invention can be used for the analysis of cells, such as amniotic cells. In the invention, DNA can directly be isolated from amniotic cells to be detected without a subculture, which greatly decreases the difficulties such as uneasy attachment, insufficient number, or failure of culture caused by the culture of amniotic cells. [0071] By using the characteristic of amniotic cells containing the entire genomic information about a fetus, the invention is able to make an analysis of the aneuploidy of all of the chromosomes of the cells, rather than examine only the sex chromosomes X and Y and chromosomes 21, 18, 13. [0072] Besides, though the method of determination involved in the invention, as compared with plasma samples, is also dependent on approximately normal distribution established on standard cellular samples, such dependency on the standard cellular samples is greatly reduced. Additionally, abnormal samples can be directly determined from data abnormalities, assuming sufficient data. [0073] By using the method of the invention, a large number of cellular detection samples can be subjected to batch analysis. Hundreds of thousands of cellular detection samples can be detected at one time, thereby greatly saving labors and costs. BRIEF DESCRIPTION OF FIGURES [0074] FIG. 1 shows a boxplot depicted in accordance with 53 cellular detection samples, in which the abscissa represents the chromosome number, and the ordinate represents the ChrN % value. [0075] FIG. 1A shows chromosomes 1-6, FIG. 1B shows chromosomes 7-12, FIG. 1C shows chromosomes 13-17, and FIG. 1D shows chromosomes 18-22. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0076] The embodiment of the invention will be described in detail in combination with the following examples. A person skilled in the art would appreciate, however, that the following examples are merely intended to make a description of the invention and would not be regarded as the limitation of the scope of the invention. If specific conditions are not specified in the examples, these examples are performed in accordance with commonly used conditions or those advised by manufacturers. If the sources of the reagents or equipment or instruments used in the invention are not specified, such as their manufacturers, all of them are commercially available. The used linkers for sequencing and the tagged sequences index come from Multiplexing Sample Preparation Oligonutide Kit provided by Illumina. [0077] In the following parentheses is manufacturers' product number for each of the reagents or kits. Example 1 Chromosomal Analysis of Uncultured Amniotic Cell 1. Isolation and Sequencing of DNA [0078] DNA of amniotic cells was isolated according to the procedure of manipulation of a small amount of genome of Tiangen Micro Kit (DP316), and quantitated with Qubit (Invitrogen, the Quant-iT™ dsDNA HS Assay Kit). The total amount of the isolated DNA varied from 100 ng to 500 ng. [0079] The isolated DNA was either the entire genomic DNA or partially degraded smear-like DNA. A DNA library was built under the standard library-building procedure provided by the modified Illumina/Solexa. Adapters were added to both ends of randomly broken DNA molecules, and attached with different tagged sequence indexes. Then these molecules were hybridized with complementary adapters on the surface of a flow cell, and allowed to be clustered in particular conditions. 36 sequencing cycles were run on an Illumina Genome Analyzer II, producing DNA fragments with 35 bp. [0080] Specifically, Diagenode Bioruptor was used to randomly break about 100-500 ng of DNA isolated from amniotic cells into 300 bp fragments. 100-500 ng of initially broken DNA was used to build a library under Illumina/Solexa. See the prior art for a detailed procedure (Illumina/Solexa manual for standard library-building provided by Illumina's website). The size of the DNA library was determined by way of 2100 Bioanalyzer (Agilent), and the inserted fragments were 300 bp. After accurate quantitation by QPCR, sequencing was performed. [0081] In the example, batch sequencing was conducted of 53 DNA samples isolated from amniotic cells according to Cluster Station and GA II×(SE sequencing) officially published by Illumina/Solexa. 2. Alignment and Statistics [0082] Refer to the prior art (see the manual concerning Pipeline method provided at Illumina's website), the sequence information obtained in step 1 was subjected to one single Pipeline process, and sequences with low quality were removed, finally resulting in ELAND alignment result against the reference sequence of the human genome of NCBI version 36. Then the number of the sole sequences located on chromosomes was statistically analyzed. [0083] The ChrN % for 22 chromosomes and the X/Y chromosome respectively from 53 samples was calculated and a boxplot (see FIG. 2 ) was drawn based on the data. The ChrN % for a particular chromosome N in particular sample M is calculated with the following formula: [0084] Percentage of a particular chromosome in detection sample M, ChrN %=the total number of the sole sequences contained in sample M and located on the corresponding chromosome of the reference sequence through alignment (S1)/the total number of the sole sequences contained in sample M and located on all of the chromosomes of the reference sequence through alignment (S2). 3. Data Analysis [0085] According to the boxplot drawn in step 2, it was firstly determined whether an outlier existed. That is, as compared with the upper and lower boarders, if a suspected sample deviated far from the point that was 1.5 times the difference between the upper-quartile and the lower-quartile away, it was likely that it differed from the standard samples in chromosome number. [0086] Specifically, the distribution of the boxplot was observed, and 8 suspected samples (sample Nos. P1-P8) were detected. A normal distribution was established by using as standard samples the data concerning 20 normal males and 10 normal females, chosen randomly from the remaining 45 standard cellular samples after the suspected samples were removed. The ChrN % mean (mean_ChrN %) for each chromosome is designated by mean_ChrN % and standard deviation (S.D._ChrN %) is given in table 1. [0000] TABLE 1 ChrN %, mean, and standard deviation (S.D.) for each chromosome in standard cells Chr1 Chr2 Chr3 Chr4 Chr5 Chr6 Chr7 Chr8 Chr9 Chr10 Chr11 Chr12 Number % % % % % % % % % % % % 1 7.850 9.295 7.542 7.381 6.876 6.660 5.499 5.468 3.942 4.747 4.603 4.744 2 7.965 9.088 7.483 6.907 6.686 6.482 5.494 5.331 4.040 4.834 4.645 4.699 3 7.935 9.121 7.414 6.989 6.649 6.491 5.500 5.324 4.035 4.834 4.704 4.695 4 7.866 9.237 7.618 7.353 6.875 6.585 5.530 5.424 3.976 4.722 4.546 4.743 5 7.847 9.179 7.371 7.100 6.784 6.509 5.535 5.374 3.988 4.843 4.587 4.721 6 7.752 9.247 7.617 7.337 6.871 6.600 5.573 5.401 3.960 4.776 4.564 4.742 7 7.920 9.149 7.501 7.178 6.826 6.607 5.515 5.360 4.003 4.792 4.598 4.748 8 8.089 8.953 7.289 6.614 6.532 6.317 5.462 5.237 4.059 4.922 4.711 4.698 9 8.155 9.005 7.190 6.459 6.565 6.267 5.529 5.238 4.154 4.950 4.819 4.573 10 7.961 9.133 7.362 6.768 6.627 6.418 5.520 5.280 3.987 4.822 4.674 4.734 11 8.079 8.980 7.217 6.602 6.493 6.294 5.504 5.219 4.078 4.921 4.770 4.712 12 7.953 9.205 7.499 7.173 6.786 6.533 5.535 5.343 3.977 4.789 4.654 4.664 13 7.986 9.051 7.360 6.848 6.701 6.446 5.541 5.376 4.065 4.822 4.701 4.689 14 8.111 9.040 7.210 6.905 6.548 6.364 5.472 5.341 4.012 4.884 4.725 4.677 15 8.032 9.002 7.325 6.818 6.571 6.369 5.537 5.345 4.064 4.913 4.672 4.682 16 8.075 8.977 7.199 6.664 6.515 6.349 5.480 5.311 4.068 4.856 4.741 4.703 17 7.878 9.184 7.502 7.221 6.793 6.592 5.523 5.405 3.990 4.763 4.588 4.727 18 7.873 9.165 7.502 7.194 6.775 6.553 5.496 5.384 4.025 4.786 4.629 4.755 19 7.911 9.119 7.574 7.286 6.830 6.507 5.539 5.365 3.949 4.781 4.577 4.695 20 8.013 9.186 7.394 6.822 6.634 6.384 5.475 5.297 4.033 4.849 4.657 4.678 21 7.739 8.991 7.232 6.822 6.503 6.260 5.374 5.214 3.941 4.797 4.629 4.591 22 7.887 8.962 7.178 6.730 6.471 6.259 5.353 5.215 3.978 4.754 4.608 4.566 23 7.921 8.903 7.258 6.803 6.438 6.285 5.372 5.234 3.973 4.739 4.624 4.626 24 7.807 8.900 7.271 6.954 6.526 6.320 5.357 5.283 3.968 4.772 4.585 4.609 25 7.681 9.020 7.359 7.172 6.685 6.440 5.421 5.255 3.922 4.667 4.502 4.665 26 7.892 8.827 7.205 6.728 6.529 6.305 5.363 5.123 3.914 4.847 4.616 4.557 27 8.071 8.730 6.993 6.186 6.159 6.034 5.267 5.150 4.044 4.919 4.790 4.556 28 7.878 8.771 7.059 6.452 6.418 6.210 5.318 5.208 3.962 4.912 4.593 4.613 29 7.803 8.985 7.335 6.934 6.613 6.382 5.428 5.268 3.892 4.744 4.510 4.658 30 7.992 8.818 7.126 6.540 6.363 6.167 5.329 5.089 4.028 4.820 4.689 4.548 mean 7.931 9.041 7.339 6.898 6.621 6.400 5.461 5.295 4.001 4.819 4.644 4.669 S.D. 0.116 0.146 0.163 0.300 0.172 0.148 0.082 0.091 0.057 0.069 0.078 0.065 Chr13 Chr14 Chr15 Chr16 Chr17 Chr18 Chr19 Chr20 Chr21 Chr22 ChrX ChrY number % % % % % % % % % % % % 1 3.917 3.294 2.762 2.401 2.380 3.051 1.120 1.966 1.295 0.920 2.163 0.126 2 3.743 3.279 2.885 2.595 2.650 2.980 1.431 2.148 1.296 1.088 2.128 0.123 3 3.770 3.268 2.914 2.565 2.602 3.027 1.434 2.112 1.270 1.073 2.154 0.119 4 3.944 3.254 2.801 2.416 2.402 3.080 1.140 2.000 1.279 0.914 2.170 0.126 5 3.880 3.234 2.866 2.545 2.576 3.049 1.354 2.064 1.275 1.050 2.154 0.112 6 3.909 3.322 2.792 2.393 2.389 3.089 1.139 1.966 1.309 0.910 2.217 0.127 7 3.868 3.305 2.833 2.451 2.481 3.002 1.266 2.033 1.327 0.942 2.165 0.129 8 3.585 3.258 2.943 2.800 2.863 2.996 1.685 2.262 1.296 1.223 2.091 0.116 9 3.590 3.205 2.926 2.860 2.960 2.879 1.669 2.271 1.339 1.240 2.046 0.111 10 3.714 3.305 2.873 2.677 2.767 3.001 1.539 2.168 1.307 1.154 2.085 0.122 11 3.638 3.303 2.927 2.787 2.872 2.947 1.687 2.244 1.294 1.275 2.041 0.115 12 3.823 3.285 2.829 2.493 2.504 3.012 1.323 2.068 1.293 1.025 2.116 0.120 13 3.734 3.282 2.819 2.676 2.670 3.002 1.479 2.100 1.299 1.097 2.135 0.121 14 3.647 3.274 2.894 2.746 2.758 2.939 1.501 2.256 1.308 1.147 2.120 0.121 15 3.720 3.262 2.891 2.663 2.730 2.976 1.551 2.176 1.287 1.164 2.122 0.130 16 3.584 3.269 2.970 2.767 2.868 2.965 1.667 2.186 1.270 1.277 2.125 0.114 17 3.864 3.246 2.827 2.475 2.476 3.036 1.228 2.024 1.297 0.963 2.277 0.120 18 3.853 3.315 2.844 2.506 2.489 3.040 1.229 2.071 1.299 0.963 2.129 0.124 19 3.950 3.312 2.845 2.457 2.484 3.065 1.234 2.031 1.265 0.962 2.136 0.125 20 3.731 3.285 2.886 2.645 2.720 2.906 1.485 2.155 1.299 1.151 2.200 0.114 21 3.690 3.224 2.829 2.522 2.618 2.919 1.384 2.119 1.269 1.107 4.224 0.003 22 3.642 3.223 2.877 2.578 2.673 2.910 1.422 2.137 1.259 1.087 4.226 0.004 23 3.680 3.234 2.824 2.536 2.585 2.968 1.380 2.098 1.265 1.062 4.187 0.004 24 3.707 3.223 2.809 2.501 2.580 2.933 1.372 2.039 1.262 1.042 4.177 0.004 25 3.829 3.214 2.740 2.388 2.390 2.978 1.211 1.975 1.259 0.929 4.293 0.004 26 3.679 3.232 2.859 2.579 2.707 2.918 1.485 2.081 1.262 1.129 4.159 0.003 27 3.404 3.207 2.912 2.899 2.968 2.893 1.802 2.344 1.263 1.330 4.077 0.003 28 3.525 3.190 2.869 2.771 2.852 2.903 1.647 2.215 1.278 1.227 4.127 0.003 29 3.786 3.177 2.778 2.456 2.498 2.980 1.258 2.037 1.271 0.986 4.216 0.003 30 3.569 3.224 2.913 2.699 2.816 2.898 1.603 2.168 1.284 1.179 4.133 0.003 mean 3.733 3.257 2.858 2.595 2.644 2.978 1.424 2.117 1.286 1.087 — — S.D. 0.135 0.040 0.055 0.147 0.175 0.060 0.187 0.099 0.021 0.120 — — mean-ChrX/ — — — — — — — — — — 2.139 0.121 Y %-M S.D.-ChrX/ — — — — — — — — — — 0.055 0.006 Y %-M mean-ChrX/ — — — — — — — — — — 4.182 0.003 Y %-F S.D.-ChrX/ — — — — — — — — — — 0.062 0.001 Y %-F [0087] Furthermore, in order to examine whether the instance of a half chromosome or an additional chromosome existed in the suspected samples, X was assigned to be 50 or 100 and the corresponding chromosomal Z reference value (cutoff value) was calculated (see table 2): [0088] Z=(mean_ChrN %×0.5×X %)/S.D._ChrN %, wherein N represents chromosomes 1-22, X is 50 or 100. [0000] TABLE 2 determination of the reference Z value (cutoff value) for trisome in the detection cells Chromosome mean_ChrN S.D._ChrN Reference Z value number % % above 50% above 100% chr1 7.9307295 0.1159668 17.0969881 34.1939762 chr2 9.0408152 0.1458970 15.4917815 30.9835629 chr3 7.3394728 0.1633916 11.2298783 22.4597567 chr4 6.8980316 0.3000703 5.7470125 11.4940249 chr5 6.6213096 0.1717845 9.6360687 19.2721373 chr6 6.3996516 0.1482759 10.7901077 21.5802154 chr7 5.4613809 0.0819567 16.6593481 33.3186962 chr8 5.2953272 0.0912159 14.5131676 29.0263351 chr9 4.0009382 0.0572472 17.4721938 34.9443876 chr10 4.8192433 0.0693516 17.3725054 34.7450108 chr11 4.6436180 0.0780559 14.8727280 29.7454561 chr12 4.6690652 0.0647597 18.0245772 36.0491544 chr13 3.7325287 0.1346539 6.9298575 13.8597151 chr14 3.2568057 0.0398485 20.4324240 40.8648480 chr15 2.8578247 0.0553827 12.9003599 25.8007199 chr16 2.5948409 0.1465308 4.4271266 8.8542531 chr17 2.6442999 0.1753843 3.7692929 7.5385857 chr18 2.9780305 0.0598664 12.4361514 24.8723027 chr19 1.4242524 0.1868697 1.9054083 3.8108167 chr20 2.1171964 0.0985564 5.3705200 10.7410400 chr21 1.2858576 0.0205784 15.6214179 31.2428358 chr22 1.0872769 0.1204085 2.2574758 4.5149516 chrX-F 4.1819271 0.0615940 −16.9737663 −33.9475326 ChrY-F 0.0034667 0.0006359 / / chrX-M 2.1387665 0.0545815 9.7962061 19.5924123 ChrY-M 0.1207910 0.0055482 5.4468013 10.8856025 [0089] The z score_ChrN for each chromosome in the suspected samples was calculated with the following formula: [0000] z score_ChrN=(ChrN % for a given chromosome in the detection samples−mean_ChrN %)/S.D._ChrN %. [0000] TABLE 3 The z score_ChrN for each chromosome in the suspected samples [0090] As seen from the analysis above, the suspected samples were 8 in total among the 53 detection samples of amniotic cells, in which, for the chromosomes in each of the suspected samples, 8 abnormalities of chromosome number with the absolute value of a z score_ChrN greater than 3 were detected (see table 3). Specifically, they were: [0091] 1) Chr21 for P1, Chr21 for P2, Chr21 for P3, and Chr21 for P4; [0092] 2) Chr18 for P5, Chr18 for P6, and Chr18 for P7; and [0093] 3) Chr13 for P8. [0094] It was determined by checking the Z value obtained when X=100 in table 2 that the number of chromosome 21 in samples P1-P4 and the number of chromosome 18 in samples P5-P7 were one more than the number of the corresponding chromosomes in the standard cells, respectively, and the number of chromosome 13 in P8 was half one more than the number of the corresponding chromosome in the standard cells. That is, P1-P4 were T21 (Down syndrome), and P5-P7 were 118 (Edwards syndrome), and P8 was mosaic T13 (mosaic Patau syndrome). The results were completely consistent with the traditional analysis results of chromosomal karyotype. Example 2 [0095] An additional 6 samples (Q1-Q6) of amniotic cells were treated and sequenced in the same way as the above to produce data for analysis. The z score_ChrN was calculated on mean_ChrN % and S.D._ChrN % calculated from 30 standard cellular samples in example 1. 3 positive samples were identified from the 6 samples. [0000] TABLE 4 The ChrN % of 6 detection samples (Q1-Q6) Q1 Q2 Q3 Q4 Q5 Q6 Chr1 % 7.900099 7.781541 7.965013 7.937310 7.835625 7.756449 Chr2 % 9.195581 8.969471 8.998068 9.137041 8.836921 9.014913 Chr3 % 7.389485 7.365766 7.389563 7.452117 7.134356 7.378118 Chr4 % 7.090694 7.005976 6.921334 7.112517 6.510565 7.058824 Chr5 % 6.759707 6.600836 6.604984 6.768853 6.357255 6.605637 Chr6 % 6.541994 6.468799 6.461957 6.545516 6.170975 6.376054 Chr7 % 5.562187 5.423140 5.522745 5.521768 5.342112 5.403700 Chr8 % 5.387074 5.344078 5.357094 5.318220 5.176933 5.275211 Chr9 % 3.946516 3.924984 4.061791 4.037918 4.007161 3.958868 Chr10 % 4.831699 4.680082 4.876470 4.845395 4.798439 4.700673 Chr11 % 4.634992 4.541423 4.682686 4.637077 4.603257 4.462601 Chr12 % 4.727456 4.552861 4.734034 4.700509 4.571935 4.594756 Chr13 % 3.871131 3.749202 3.677764 3.875716 3.475357 3.776552 Chr14 % 3.261377 3.247342 3.285671 3.281681 3.238633 3.207609 Chr15 % 2.875226 2.782605 2.926826 2.866104 2.830466 2.757703 Chr16 % 2.516559 2.443884 2.624248 2.524383 2.665946 2.413713 Chr17 % 2.519897 2.481007 2.684055 2.561488 2.725292 2.495129 Chr18 % 3.026389 2.939323 3.027751 2.994205 2.893438 2.985936 Chr19 % 1.291162 1.240504 1.479644 1.317938 1.482326 1.235699 Chr20 % 2.096249 2.063225 2.174512 2.076472 2.173705 2.049467 Chr21 % 1.290966 1.267192 1.297270 1.291611 1.896099 1.297050 Chr22 % 0.992960 0.989674 1.125718 1.017386 1.164497 0.995698 ChrX % 2.173990 4.134076 2.117655 2.177186 4.104752 4.197133 ChrY % 0.116611 0.003010 0.003148 0.001590 0.003956 0.002508 [0000] TABLE 5 The z score_ChrN for 6 samples calculated from the mean-ChrN% and S.D._ChrN% of 30 negative samples in example 1 [0096] As seen from the results, Q5 had an extra copy of chromosome 21 than the standard cells, which was T21; Q3, Q4 missed one copy of chromosome X, which was 45×0 (Turner syndrome). The results were completely consistent with the traditional analysis results of chromosomal karyotype. [0097] Although the examples of the invention have been described in great detail, a person skilled in the art will understand that, according to all of disclosed teachings, a variety of modification and replacement may be made of those details. The changes are covered by the scope of protection of the invention. The whole scope of the invention is defined by attached claims and its equivalent.

The present invention involves an analysis method of cellular chromosomes, particularly involves a method of analyzing whether a difference exists in the chromosome number between amniotic cells and standard cells by a sequencing method.

BACKGROUND OF THE INVENTION 1. Field of Invention. This invention relates to the treatment of materials and more particularly to a method and apparatus for processing materials to produce recyclable waste. 2. Description of Relevant Art. The ever-increasing waste disposal problems and interest in recycling of various materials has in recent years spurred the design and development of many systems and devices for processing waste and other materials either for more efficient disposal in land fills or for recycling purposes. Many elaborate systems and devices have emerged. To date none of these systems specifically target the recycling of filters; oil, gas and air for example. There are approximately 200 million registered vehicles on the road in the United States, each of these undergoing three or more filter changes in any given year. The disposal of oil, gas and air filters, usually filled respectively with waste oil, gas and particulates, presents environmental and practical problems. The filters are generally composed of a metal shell, a filter paper interior, and an accompanying gasket. Disposal of the filters presents many recycling opportunities if it were possible to economically separate the various components of the filters. Traditional garbage shredders or centrifugal mills, however, rather than separating the components tend to entwine them more thoroughly than they are in the original filter thereby precluding any recycling possibilities. Therefore, a need exists for a method and apparatus for treating used filters in a manner which allows their various components to be recycled. SUMMARY OF INVENTION The present invention in general terms concerns an apparatus and method for processing materials such as used filters in a manner that allows for recycling of the various components of the filter. Those components are: an oil, gas or particulate saturated filter paper, a rubber o-ring and a metal housing. The apparatus consists of a plurality of parts including a sorting pan, a shredder, a centrifugal mill, a settling container, a magnetic separator, recycling containers for paper flocculate and for steel, and a fluid collection pan for oil or gas, along with various conveying means linking the various components of the apparatus. In operation and with a specific reference to the processing of filters, the filters of various sizes are deposited in a sorting bin. The sorting bin has two outlets: one for filters of a standard size and the other for filters of an above standard size. The standard size conveyor transports filters of a standard size directly to the inlet of the centrifugal mill. Filters of a nonstandard size are passed by the above standard size conveyor to the shredder which breaks the filters down into a size approximating that of standard filters. At the output of the shredder the shredded above standard size filters are deposited on an above standard size shredded conveyor and transported to the intake of the centrifugal mill. Thus the intake of the centrifugal mill is presented with standard size filters and above standard size shredded filters. At the intake of the centrifugal mill the filters are entrained in a highly turbulent incoming airstream. The airstream and fan blades rotating in the mill are believed to entrain the incoming filters in a helical path from intake to outlet. In the course of moving along this path the filters are subject to sufficient impacting and turbulence to first separate the filter's steel shell from the paper filter core and then to flocculate the paper which absorbs all liquid residue in the air stream and to simultaneously shard the steel shell into a recyclable size. A tangentially positioned outlet on the bottom perimeter of the centrifugal mill provides a high speed exit point for the turbulent waste stream consisting of air, oil or gas soaked flocculate, rubber o-rings and steel shard. The waste stream is captured in a settling bin. The steel shard impacts a settling bin wear guard which dampens its velocity and allows it to settle to the bottom of the settling bin. The flocculate also is collected on the bottom of the settling bin. All solid components of the waste stream are continuously removed from the settling bin by a settling bin conveyor which transports the solid waste to the settling bin outlet. The gaseous portion of the waste stream exits the settling bin through whatever environmental filtration units are required to remove oil or gas vapor from the air. The solid portion of the waste stream is transported from the settling bin outlet by a waste stream conveyor. Intermediate the input and outlet of the waste stream conveyor is a magnetic separation conveyor. This physically removes the metal portion of the waste stream, specifically steel shard, and deposits it in the scrap steel recycling bin. The remaining portion of the waste stream, consisting of flocculate and rubber gaskets is deposited by the waste stream conveyor in the flocculate recycling bin. Intermediate the outlet of the waste stream conveyor and the input of the flocculate recycling bin, rubber gaskets which typically pass through the mill without change, may be removed manually, or by other suitable means. Underlying the whole processing unit is an oil or gas collection pan to collect any drippings resulting from the process and to allow for the recycling of waste oil or gas. The apparatus and method disclosed thus allows for the processing at the input of used filters and the retrieval at the output of four recyclable waste components of those filters, specifically, used oil or gas, scrap steel shard, rubber o-rings and combustible oil or gas soaked flocculate, each having its own recycling market. Accordingly, it is a primary object of the present invention to provide an environmentally responsible method for processing materials such as used filters in a manner which allows for recycling of the various components of those materials, and it is another object of the invention to provide an apparatus for practicing the method of processing such materials. Other aspects, features and details of the present invention can be more completely understood by reference to the following detailed description of a preferred embodiment taken in conjunction with the drawings and the appended claims. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a side elevation of an oil filter processing system. FIG. 2 is a cross-section of a typical oil filter for automotive use processed in the system of FIG. 1. FIG. 3 is an isometric of a mill for processing automotive filters. FIG. 4 is a horizontal cross-section taken along line 4--4 of FIG. 3. FIG. 5 is a horizontal cross-section taken along line 5--5 of FIG. 3. FIG. 6 is an isometric of the fan unit elements with the outside container shown in dashed lines. FIG. 7 is an exploded isometric of the fan blade units. DESCRIPTION OF THE PREFERRED EMBODIMENT While the method and apparatus of the present invention may serve other desirable functions, for example, processing used paint or aerosol canisters or air or gas filters, for purposes of disclosure, it is being described as directed to the processing of used oil filters to produce a recyclable waste stream. In FIG. 1 a recycling system 10, for used oil filters of varying sizes is shown. Filters 12 are placed in a sorting bin 14 at the intake of the process and from these used oil filters four recyclable waste products are produced. The four recyclable waste products are scrap steel, combustible oil soaked flocculate, used oil, and rubber gaskets. An oil filter 12 of the type shown in FIG. 2 is the basic waste unit being processed. The oil filter of the conventional type is found in cars and trucks. The filter itself generally consists of a steel shell 14, a steel bottom plate 16, a rubber gasket 18 on the bottom plate, a filter paper 20 suitable for removing particulates from a lubricant oil stream, and a filter core 22 for directing the oil on its outgoing or return path. The apparatus of the current invention consists generally of a large oil collection pan 24 over which are suspended in order from input to outlet: a sorting pan 14, an above standard size shredder 26, a centrifugal mill 28, a settling bin 30, a magnetic separator 32, and recycling bins for steel 34 and for oil soaked flocculate 36. In greater detail, the sorting bin 14 into which standard size and above standard size used oil filters are deposited provides, through conventional vibratory or manual means, for the separation of those two filter sizes. Standard size filters exit the sorting bin at a standard size exit point 38. Above standard size filters exit the sorting bin at an above standard size exit 40. There are two conveyors connected to the sorting bin. The first conveyor, the standard size conveyor 42 has an input end 44 connected the standard size exit 38 and an output end 46 connected to the intake 48 of the centrifugal mill 28. The second conveyor, the above standard size conveyor 50 has an input end 52 connected to the above standard size exit 40 of the sorting bin and an output end 54 connected to the intake of a shredder 26. The shredder 26 accepts above standard size oil filters as input and outputs shredded above standard size oil filters having a size approximating that of a standard size oil filter. The output 58 of the shredder is connected to the input 60 of the above standard sized shredded conveyor 62. The output 64 of that conveyor is connected to the intake 48 of the centrifugal mill unit. The centrifugal mill 28 shown in FIGS. 3-7 consists of a cylindrical shell 66 having an inside diameter of approximately 44 inches and a height of approximately 603/4 inches. The top of the cylindrical chamber consists of a circular top plate 68, top plate tie down bolts 70, a centrally located top plate fan bearing assembly 72 and an intake opening 48 measuring approximately 30 inches by 15.5 inches. An outlet opening 74 having approximately 1/6th the area of the intake opening is provided in the cylindrical shell adjacent to the bottom thereof and in the preferred embodiment has a ten inch diameter pipe 76 tangentially intersecting the perimeter of the cylindrical shell, 90 degrees offset from the intake opening. A motor unit 78 (FIG. 4) of approximately 100 horsepower is mounted in a base support structure 80 and is connected by a motor pulley 82 and drive belts 84 to a fan shaft pulley 86. The motor unit 78 and pulleys 82, 86 are geared so as to drive the fan shaft pulley 86 at approximately 1300 rpm. The fan shaft 88 is best shown in FIG. 5 and consists of 4 inch diameter steel bar stock 90 appropriately machined to accommodate the fan blade unit assembly 92 and to fit in the bearing unit 72 in the top plate of the cylindrical chamber and a bearing unit 73 (FIG. 5) in a bottom plate 80 of the mill. Attached to the fan shaft 90 at predefined intervals are a series of seven fan blade units each having a distinct purpose. The fan blades of each fan blade unit are secured to the fan shaft by a circular disc plate approximately 3/8 inch in thickness and 19.5 inches in diameter. The disc plates are rigidly mounted to the four inch diameter fan blade shaft 90 and rotate in unison therewith. All fan blades extend to within 1 inch of the interior wall of the cylindrical shell so that the tip of the fan blades define a radius for a fan blade unit that is approximately 45% less than the inside radius of the shell 66. The tips of the fan blades travel at a velocity of approximately 125 ft/sec. The first and second fan blade units are comminutor blades. These separate the used oil filter shell from the filter paper. The first comminutor fan blade unit 94 consists of an anchored circular disk plate 96 to which are radially bolted two diametrically opposing fan blades 98, 100. The unit is anchored to the fan shaft 201/8 inches distant from the top plate 68 of the mill. The second fan blade unit 102 is identical to the first, consisting of two diametrically opposed blades 104, 106, bolted to a circular anchor disk plate 108. The second comminutor fan blade unit is anchored 61/8 inches below the first fan blade unit 94. Additionally, the two blades 104, 106 of this unit are offset 90 degrees with respect to the two blades 98,100 of the first comminutor fan blade unit 1. In the preferred embodiment the comminutor fan blades 98, 100, 104, 106 are rectangular steel bar stock 1.5 inches thick, and four inches in width. The third through sixth fan blade units are turbulator units which flocculate the filter paper and shard the oil filter steel shell. The third fan blade unit 110 consists of a circular anchored disc plate 112, to which are radially bolted three equally spaced fan blades 114, 116, 118 at an angle of 120 degrees relative to each adjacent fan blade. The unit is anchored to the fan shaft 7 inches beneath the second comminutor fan blade unit 102. The fourth fan blade unit 120 consists of an anchored disc plate 122, to which are radially bolted two diametrically opposed fan blades 124, 126 aligned with the fan blades 104 and 106 of the second fan blade unit. The unit is anchored to the fan shaft 6 and 5/8 inches below the third turbulator fan blade unit 110. The fifth fan blade unit 128 consists of an anchored disc plate 130, to which are radially bolted three equally spaced fan blades 132, 134, 136 at an angle of 120 degrees relative to each adjacent fan blade. The unit is anchored to the fan shaft 6 inches beneath the fourth turbulator fan blade unit 120. Additionally the three blades 132, 134, 136 of this unit are offset 60 degrees with respect to the three blades 114, 116, 118 of the third turbulator fan blade unit 110. The sixth fan blade unit 138 consists of an anchored disc plate 140, to which are radially bolted two equally spaced diametrically opposed fan blades 142, 144. The unit is anchored 5 and 1/8 inches beneath the fifth turbulator fan blade unit 128. Additionally the two blades 142, 144 of this unit are offset 90 degrees with respect to the two blades 124, 126 of the fourth turbulator fan blade unit 120. In the preferred embodiment the turbulator fan blades are rectangular steel bar stock 1.0 inches thick, and four inches in width. The seventh and final fan blade unit 146 is an impeller unit. This fan blade creates the high volume airstream which carries the separated waste from the centrifugal mill 28. The last fan blade unit consists of an anchored disc plate 148, to which are radially bolted four equally spaced fan blades 150, 152, 154, 156 at an angle of 90 degrees relative to each adjacent fan blade. The unit is anchored to the fan shaft 8 and 3/8 inches beneath the sixth turbulator fan blade unit 138. In the preferred embodiment the impeller fan blades are angle iron having horizontal and vertical legs that are six inches wide and half-inch thick. The tangential output 74 of the centrifugal fan unit 28 is connected in communication with the input 158 of the settling bin 30 and allows for the transport of the waste stream between the two. The settling bin in the preferred embodiment is a rectangular enclosure having four side walls and a top wall. The bin includes a wear guard 160 draped from the top wall and extending to the bottom of the settling bin. In the preferred embodiment the wear guard might consist of a series of chains suspended from the top wall. The floor of the settling bin is a continuous conveyor unit 166 moving from the input to the output. To process the large volume of air flow emanating from the centrifugal fan an air emission control unit 168 may be mounted on the top wall for filtering the exiting air stream according to local environmental regulations. At the outlet 170 of the settling bin 30 a waste stream conveyor 172 input 174 is connected. The output of the waste stream conveyor 176 is adjacent to and overlies the input 178 of the flocculate recycling bin 36. Intermediate the input and the output of the waste stream conveyor is the 180 input of a magnetic separator conveyor 182. The magnetic separator conveyor may consist of a permanently magnetized belt which makes physical contact with the waste stream on the waste stream conveyor. Magnetic waste, in this case steel shard, adhering to the magnetized belt may be continuously scraped off the belt. The output 184 of the magnetic separator conveyor 182 is adjacent to and overlies the input 186 of the scrap steel recycling bin 34. Finally, the recycling apparatus includes an oil collection pan 24 underlying all of the above mentioned components, so as to collect any oil drippings from any component of the system. In operation oil filters of varying sizes are deposited in the sorting bin 14. Standard and above standard size oil filters are therein separated. Sorting can be manual or more efficiently by a vibratory feed system using known technology which separates standard sized oil filters placing them on the input 38 of the standard size conveyor 42 and above standard size oil filters placing them on the input 52 of the above standard size conveyor 50. The standard size oil filters are transported to the intake 48 of the centrifugal mill 28. The above standard size oil filters are transported to the shredder 26. The shredder reduces the size of the above standard size oil filters to a size approximating that of a standard sized filter. The shredder may function by grinding the filters between opposing wheels or by an impeller motion of an impact blade in a manner that is well known in the grinding art. In either case above standard sized used oil filters must be sufficiently shredded to reduce their size to that approximating a standard sized oil filter. The shredder unit however, preferably does not reduce the size of the above standard sized units so much as to entwine metal and filter paper in a manner that prevents their subsequent separation into a recyclable waste stream. At its output 58 the shredder 26 deposits the shredded mass on an above standard size shredded conveyor 62 which conveyor transports the shredded oil filters to the intake 48 of the centrifugal mill 28. The next step is for the centrifugal mill to accept the input of standard size and above standard size shredded used oil filters and to turn them into a recyclable separable waste stream. A high volume of air, approximately 10,000 cubic feet per minute, is entrained into the centrifugal chamber 28 by the fan blade units 92. The first two fan blade units 94, 102 are comminutor fan blade units impact the oil filters and separate the oil filter shell, the paper core, and the gasket. The third through sixth fan blade units 110, 120, 128, 138 turbulate the air stream and the entrained oil filter materials flocculating the paper and causing it to absorb all oil residue. These blade units also take the oil filter steel shell 66 and shard it into suitable sizes for recycling. The dwell time of the waste products in the air stream is determined by the ratio of the intake 48 to the outlet 74 area of the centrifugal mill 28. This is adjustable by means of a sliding intake baffle, not shown, and is generally in the ratio of 6 to 1. This results in sufficient dwell time to allow the waste stream to be separated into various recyclable by products. The seventh fan blade unit 146 forces the air stream into the tangential exit at the base of the chamber from which the waste stream is directed to the intake 158 of the settling bin 30. The wear guard baffle 160 in the settling bin 30 intercepts the metal shard and thereby reduces the wear of that shard on the back wall of the settling bin. The recyclable components of the waste stream settle to the bottom of the settling bin and are transported therefrom by the conveyor 166 to the exit 170 of the settling bin 30. The large volume of air received by the settling bin can be environmentally processed with the filtering device 168 in the settling bin to meet local environmental requirements. The next step in the process is to take the waste stream from the settling bin conveyor 166 and pass it to the waste stream conveyor 170. The waste stream at this point consists of rubber gaskets, oil soaked filter paper, flocculate, and steel shard. The steel shard is independently recyclable, and therefore the next step in the process is to pass the waste stream through a magnetic separation device 32. There are several types of magnetic separators which can be used, one of which is a series of permanent magnets on a belt. When positioned so as to provide physical contact between the belt and the waste stream, on the waste stream conveyor, the permanent magnets tend to lift the steel shard from the waste stream conveyor 170. The steel shard is then mechanically removed from the magnets, by scraping, and deposited in the scrap steel recycling container 34. The waste stream, thus deprived of recyclable magnetic steel products is transported to the flocculate recycling container 36. It may be desirable to remove rubber gaskets from this flocculate waste stream and this can be achieved either manually or by a conventional vibratory separation mechanism. The waste stream thus separated consists of four recyclable products, specifically steel shard, oil soaked flocculate filter paper, rubber gaskets, and oil residue collected continuously at all points along the apparatus by an underlying oil pan 24. In another preferred embodiment not having to do with filters, the aforementioned apparatus and method could be advantageously used to process other materials such as paint containers or aerosol cans. The method and apparatus of processing would be similar to that disclosed in connection with oil filters, the only exception being that the recyclable components would be limited to liquid paint residue or the like collected in pan 24, metal shard collected in container 34 and, in the absence of waste paper, there would be no flocculate collection. It might, however, be advantageous to introduce waste paper into the waste stream in order to soak up any liquid residue and thereby possibly produce a combustible recyclable resource. While there has been described above the principles of the present invention in conjunction with specific apparatus, it is to be clearly understood that the foregoing description is made only by way of example and not as a limitation to the scope of the invention.

There is disclosed a method and apparatus for processing material to produce recyclable waste. The material may be sorted, centrifugally milled and magnetically separated in a manner sufficient to produce multiple recyclable waste products.

BACKGROUND OF THE INVENTION Captopril, (S)-1-(3-mercapto-2-methyl-1-oxopropyl)-L-proline, having the structural formula ##STR4## is an orally active angiotensin converting enzyme inhibitor useful for treating hypertension and congestive heart failue. See Ondetti et al. U.S. Pat. No. 4,105,776. Enalapril, (S)-1-[N-[1-(ethoxycarbonyl)-3-phenylpropyl]-L-alanyl]-L-proline, having the structural formula ##STR5## is also an orally active angiotensin converting enzyme inhibitor. Enalapril contains the L-alanyl-L-proline dipeptide. A related compound, lisinopril, also possesses oral angiotensin converting enzyme inhibitor activity and contains the L-lysyl-L-proline dipeptide. See Harris et al. U.S. Pat. No. 4,374,829. Fosinopril sodium, (4S)-4-cyclohexyl-1-[[(R)[(S)-1-hydroxy-2-methylpropoxy](4-phenylbutyl)phosphinyl]acetyl]-L-proline propionate (ester), sodium salt having the structural formula ##STR6## is also an orally active angiotensin converting enzyme inhibitor useful for treating hypertension. See Petrillo U.S. Pat. No. 4,337,201. Haslanger et al. in U.S. Pat. No. 4,749,688 disclose treating hypertension by administering neutral metalloendopeptidase inhibitors alone or in combination with atrial peptides or angiotensin converting enzyme inhibitors. Neustadt in U.S. Pat. No. 5,075,302 disclose that mercaptoacyl amino lactams of the formula ##STR7## wherein Y includes propylene and butylene, R 1 is lower alkyl, aryl or heteroaryl, and R 2 is hydrogen, lower alkyl, lower alkoxy lower alkyl, aryl-lower alkyl or heteroaryl-lower alkyl are endopeptidase inhibitors. Neustadt disclose employing such compounds alone or in combination with angiotensin converting enzyme inhibitors to treat cardiovascular diseases such as hypertension, congestive heart failure, edema, and renal insufficiency. Delaney et al. U.K. Patent 2,207,351 disclose that endopeptidase inhibitors produce diuresis and natriuresis and are useful alone or in combination with angiotensin converting enzyme inhibitors for the reduction of blood pressure. Delaney et al. include various mercapto and acylmercapto amino acids and dipeptides among their endopeptidase inhibiting compounds. Flynn et al. in European Patent Application 481,522 disclose dual inhibitors of enkephalinase and angiotensin converting enzyme of the formulas ##STR8## wherein n is zero or one and z is O, S, --NR 6 -- or ##STR9## Additional tricyclic dual inhibitors are disclosed by Warshawsky et al. in European Patent Applications 534,363, 534,396 and 534,492. Karanewsky et al. in U.S. Pat. Nos. 4,432,971 and 4,432,972 disclose phosphonamidate angiotensin converting enzyme inhibitors of the formula ##STR10## wherein X is a substituted imino or amino acid or ester. Karanewsky in U.S. Pat. No. 4,460,579 discloses angiotensin converting enzyme inhibitors including those of the formula ##STR11## and in U.S. Pat. No. 4,711,884 discloses angiotensin converting enzyme inhibitors including those of the formula ##STR12## wherein X is a thiazine or thiazepine. Ruyle in U.S. Pat. No. 4,584,294 disclose angiotensin converting enzyme inhibitors of the formula ##STR13## Parsons et al. in U.S. Pat. No. 4,873,235 disclose angiotensin converting enzyme inhibitors of the formula ##STR14## SUMMARY OF THE INVENTION This invention is directed to novel compounds containing a fused multiple ring lactam which are useful as angiotensin converting enzyme inhibitors. Some of these compounds also possess neutral endopeptidase inhibitory activity. This invention is also directed to pharmaceutical compositions containing such selective or dual action inhibitors and the method of using such compositions. This invention is also directed to the process for preparing such novel compounds and novel intermediates. The novel fused multiple ring lactam compounds of this invention include those compounds of the formula ##STR15## and pharmaceutically acceptable salts thereof wherein: ##STR16## R 1 and R 12 are independently selected from hydrogen, alkyl, alkenyl, cycloalkyl, substituted alkyl, substituted alkenyl, aryl, substituted aryl, heteroaryl, cycloalkyl-alkylene-, aryl-alkylene-, substituted aryl-alkylene-, and heteroaryl-alkylene- or R 1 and R 12 taken together with the carbon to which they are attached complete a cycloalkyl ring or a benzofused cycloalkyl ring; R 2 is hydrogen, ##STR17## or R 11 --S--; R 3 , R 5 and R 7 are independently selected from hydrogen, alkyl, substituted alkyl, aryl-(CH 2 ) p --, substituted aryl-(CH 2 ) p --, heteroaryl-(CH 2 ) p --, ##STR18## R 4 is alkyl, cycloalkyl-(CH 2 ) p --, substituted alkyl, aryl-(CH 2 ) p --, substituted aryl-(CH 2 ) p --, or heteroaryl-(CH 2 ) p --; R 6 is alkyl, substituted alkyl, cycloalkyl-(CH 2 ) p --, aryl-(CH 2 ) p --, substituted aryl-(CH 2 ) p --, or heteroaryl-(CH 2 ) p --; R 8 is hydrogen, lower alkyl, cycloalkyl, or phenyl; R 9 is hydrogen, lower alkyl, lower alkoxy, or phenyl; R 10 is lower alkyl or aryl-(CH 2 ) p --; R 11 is alkyl, substituted alkyl, cycloalkyl-(CH 2 ) p --, aryl-(CH 2 ) p --, substituted aryl-(CH 2 ) p --, heteroaryl-(CH 2 ) p --, or --S--R 11 completes a symmetrical disulfide wherein R 11 is ##STR19## m is one or two; n is zero or one; q is zero or an integer from 1 to 3; p is zero or an integer from 1 to 6; ##STR20## represents an aromatic heteroatom containing ring selected from ##STR21## X 1 is S or NH; X 2 is S, O, or NH; and R 13 is hydrogen, lower alkyl, lower alkoxy, lower alkylthio, chloro, bromo, fluoro, trifluoromethyl, amino, --NH(lower alkyl), --N(lower alkyl) 2 , or hydroxy. DETAILED DESCRIPTION OF THE INVENTION The term "alkyl" refers to straight or branched chain radicals having up to seven carbon atoms. The term "lower alkyl" refers to straight or branched radicals having up to four carbon atoms and is a preferred subgrouping for the term alkyl. The term "substituted alkyl" refers to such straight or branched chain radicals of 1 to 7 carbons wherein one or more, preferably one, two, or three, hydrogens have been replaced by a hydroxy, amino, cyano, halo, trifluoromethyl, --NH(lower alkyl), --N(lower alkyl) 2 , lower alkoxy, lower alkylthio, or carboxy. The term "halo" refers to chloro, bromo, fluoro, or iodo. The terms "lower alkoxy" and "lower alkylthio" refer to such lower alkyl groups as defined above attached to an oxygen or sulfur. The term "cycloalkyl" refers to saturated rings of 3 to 7 carbon atoms with cyclopentyl and cyclohexyl being most preferred. The term "alkenyl" refers to straight or branched chain radicals of 3 to 7 carbon atoms having one or two double bonds. Preferred "alkenyl" groups are straight chain radicals of 3 to 5 carbons having one double bond. The term "substituted alkenyl" refers to such straight or branched radicals of 3 to 7 carbons having one or two double bonds wherein a hydrogen has been replaced by a hydroxy, amino, halo, trifluoromethyl, cyano, --NH(lower alkyl), --N(lower alkyl) 2 , lower alkoxy, lower alkylthio, or carboxy. The term "alkylene" refers to straight or branched chain radicals having up to seven carbon atoms, i.e. --CH 2 --, --(CH 2 ) 2 --, --(CH 2 ) 3 --, --(CH 2 ) 4 --, ##STR22## etc. The term "aryl" refers to phenyl, 1-naphthyl, and 2-naphthyl. The term "substituted aryl" refers to phenyl, 1-naphthyl, and 2-naphthyl having a substituent selected from lower alkyl, lower alkoxy, lower alkylthio, halo, hydroxy, trifluoromethyl, amino, --NH(lower alkyl), or --N(lower alkyl) 2 , and di- and tri-substituted phenyl, 1-naphthyl, or 2-naphthyl wherein said substituents are selected from methyl, methoxy, methylthio, halo, hydroxy, and amino. The term "heteroaryl" refers to unsaturated rings of 5 or 6 atoms containing one or two O and S atoms and/or one to four N atoms provided that the total number of hetero atoms in the ring is 4 or less. The heteroaryl ring is attached by way of an available carbon or nitrogen atom. Preferred heteroaryl groups include 2-, 3-, or 4-pyridyl, 4-imidazolyl, 4-thiazolyl, 2- and 3-thienyl, and 2- and 3-furyl. The term heteroaryl also includes bicyclic rings wherein the five or six membered ring containing O, S, and N atoms as defined above is fused to a benzene or pyridyl ring. Preferred bicyclic rings are 2- and 3-indolyl and 4- and 5-quinolinyl. The mono or bicyclic heteroaryl ring can also be additionally substituted at an available carbon atom by a lower alkyl, halo, hydroxy, benzyl, or cyclohexylmethyl. Also, if the mono or bicyclic ring has an available N-atom such N atom can also be substituted by an N-protecting group such as ##STR23## 2,4-dinitrophenyl, lower alkyl, benzyl, or benzhydryl. The compounds of formula I wherein A is ##STR24## with a fused multiple ring lactam of the formula ##STR25## to give the product of formula ##STR26## wherein R 3 is an easily removable ester protecting group such as methyl, ethyl, t-butyl, or benzyl. The above reaction can be performed in an organic solvent such as methylene chloride and in the presence of a coupling reagent such as 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, dicylcohexylcarbodiimide, benzotriazol-1-yloxytris(dimethylamino)phosphonium hexafluorophosphate, or carbonyldiimidazole. Alternatively, the acylmercapto carboxylic acid of formula II can be converted to an activated form prior to coupling such as an acid chloride, mixed anhydride, symmetrical anhydride, activated ester, etc. The product of formula IV can be converted to the mercaptan product of formula I wherein R 2 is hydrogen and R 3 is hydrogen by methods known in the art. For example, when R 6 is methyl and R 3 is methyl or ethyl treatment with methanolic sodium hydroxide yields the products wherein R 2 and R 3 are hydrogen. The products of formula I wherein R 2 is hydrogen can be acylated with an acyl halide of the formula ##STR27## wherein halo is F, Cl or Br or acylated with an anhydride of the formula ##STR28## to give other products of formula I wherein R 2 is ##STR29## The products of formula I wherein R 2 is --S--R 11 and R 11 is alkyl, substituted alkyl, cycloalkyl-(CH 2 ) p --, aryl-(CH 2 ) p --, substituted aryl-(CH 2 ) p --, or heteroaryl-(CH 2 ) p -- can be prepared by reacting the products of formula I wherein R 2 is hydrogen with a sulfonyl compound of the formula (VII) H.sub.3 C--SO.sub.2 --S--R.sub.11 in an aqueous alcohol solvent to yield the desired products. The compounds of formula VII are known in the literature or can be prepared by known methods, see for example, Smith et al., Biochemistry, 14, p 766-771 (1975). The symmetrical disulfide products of formula I can be prepared by direct oxidation of the product of formula I wherein R 2 is hydrogen with iodine as note, for example, Ondetti et al. U.S. Pat. No. 4,105,776. The acylmercapto sidechain compounds of formula II wherein R 12 is hydrogen are described in the literature. See, for example, Ondetti et al. U.S. Pat. Nos. 4,105,776 and 4,339,600, Haslanger et al. U.S. Pat. No. 4,801,609, Delaney et al. U.S. Pat. No. 4,722,810, etc. The acylmercapto sidechain compounds of formula II wherein R 1 and R 12 are both other than hydrogen and n is zero can be prepared by reacting the substituted carboxylic acid of the formula ##STR30## with bis[(4-methoxy)phenyl]methyldisulfide in the presence of lithium diisopropylamide to give the compound of the formula ##STR31## Treatment of the compound of formula IX with strong acid such as trifluoromethanesulfonic acid removes the methoxybenzyl protecting group and is followed by acylation with the acyl halide of formula V or anhydride of formula VI to give the compound of formula II wherein R 1 and R 12 are both other than hydrogen and n is zero. The acylmercapto sidechain compounds of formula II wherein R 1 and R 12 are both other than hydrogen and n is one can be prepared by reacting the substituted carboxylic acid of the formula ##STR32## with para-toluenesulfonyl chloride in pyridine to give the lactone of the formula ##STR33## Treatment of the lactone of formula XI with a cesium thioacid of the formula ##STR34## in the presence of dimethylformamide yields the desired acylmercapto sidechain of formula II wherein R 1 and R 12 are both other than hydrogen and n is one. The compounds of formula I wherein A is ##STR35## can be prepared by coupling the acid of the formula ##STR36## wherein R 7 is an ester protecting group with the fused multiple ring lactam of formula III in the presence of a coupling reagent as defined above to give the product of the formula ##STR37## Alternatively, the acid of formula XIII can be converted to an activated form such as an acid chloride prior to the coupling reaction. The acids of formula XIII are described by Warshawsky et al. in European Patent Application 534,396 and 534,492. The compounds of formula I wherein A is ##STR38## can be prepared by reacting a keto acid or ester of the formula ##STR39## with fused multiple ring lactam of formula III under reducing conditions to give the product of the formula ##STR40## The keto acids and esters of formula XV are described in the literature. See, for example, Ruyle U.S. Pat. No. 4,584,294 and Parsons et al. U.S. Pat. No. 4,873,235. Alternatively, the fused multiple ring lactam compound formula III can be reacted with a triflate of the formula ##STR41## to give the product of formula XVI. The compounds of formula I wherein A is ##STR42## can be prepared by coupling a phosphonochloridate of the formula ##STR43## wherein R 5 is lower alkyl or benzyl with a fused multiple ring lactam of formula III to give the product of the formula ##STR44## Preferably, the compound of formula III is in its hydrochloride salt form and R 3 is lower alkyl or benzyl. The R 3 and R 5 ester protecting groups can be removed, for example, by hydrogenation to give the corresponding products of formula I wherein R 3 and R 5 are hydrogen. The phosphonochloridates of formula XVIII are known in the literature. See, for example, Karanewsky et al. U.S. Pat. Nos. 4,432,971 and 4,432,972 and Karanewsky U.S. Pat. No. 4,460,579. The ester products of formula I wherein R 5 or R 7 is ##STR45## can be prepared by treating the corresponding compounds of formula I wherein R 5 or R 7 is hydrogen and R 3 is an ester protecting group with a compound of the formula ##STR46## wherein L is a leaving group such as chloro, bromo, or tolylsulfonyloxy followed by removal of the R 3 ester protecting group. The ester products of formula I wherein R 3 is ##STR47## can be prepared by treating the corresponding compounds of formula I wherein R 3 is hydrogen and R 2 is ##STR48## with a compound of formula XX. The fused multiple ring lactams of formula III can be prepared according to the following process which also forms part of thia invention. An N-protected carboxylic acid of the formula ##STR49## can be coupled with the amino acid ester of the formula ##STR50## to give the compound of the formula ##STR51## This reaction can be performed in the presence of a coupling reagent as defined above. The alcohol of formula XXIII can be converted to the corresponding aldehyde such as by treatment with 4-methylmorpholine N-oxide and tetrapropyl ammonium perruthenate or treatment with oxalyl chloride, dimethylsulfoxide, and triethylamine. This aldehyde can then be cyclized by treatment with a strong acid such as trifluoroacetic acid or trifluoroacetic acid followed by trifluoromethanesulfonic acid to give the compound of the formula ##STR52## Alternatively, the N-protected carboxylic acid of the formula XXI can be coupled with the amino acid ester of the formula ##STR53## to give the compound of the formula ##STR54## The compound of formula XXVI can be cyclized by treatment with strong acid such as trifluoroacetic acid or trifluoroacetic acid followed by trifluoromethanesulfonic acid to give the compound of formula XXIV. Treatment of compound XXIV with hydrazine monohydrate removes the N-phthalimido protecting group and gives the fused multiple ring lactam of formula III. The compounds of formula I contain three asymmetric centers in the fused multiple ring lactam portion of the structure with an additional center possible in the side chain. While the optically pure form of the fused multiple ring lactam described above is preferred, all such forms are within the scope of this invention. The above described processes can utilize racemates, enantiomers, or diastereomers as starting materials. When diastereomeric compounds are prepared, they can be separated by conventional chromatographic or fractional crystallization methods. Preferably, the hydrogen attached to the bridgehead carbon is in the orientation shown below ##STR55## The compounds of formula I wherein R 3 , R 5 and/or R 7 are hydrogen can be isolated in the form of a pharmaceutically acceptable salt. Suitable salts for this purpose are alkali metal salts such as sodium and potassium, alkaline earth metal salts such as calcium and magnesium, and salts derived from amino acids such as arginine, lysine, etc. These salts are obtained by reacting the acid form of the compound with an equivalent of base supplying the desired ion in a medium in which the salt precipitates or in aqueous medium and then lyophilizing. Preferred compounds of this invention are those wherein: A is ##STR56## R 2 is hydrogen, ##STR57## or R 11 --S--; R 3 is hydrogen or lower alkyl of 1 to 4 carbons; n is zero or one; R 12 is hydrogen; R 11 is lower alkyl of 1 to 4 carbons; R 1 is aryl-CH 2 --, substituted aryl-CH 2 --, heteroaryl-CH 2 --, cycloalkyl-CH 2 -- wherein the cycloalkyl is of 5 to 7 carbons, or straight or branched chain alkyl of 1 to 7 carbons; R 6 is lower alkyl of 1 to 4 carbons or phenyl; m is one or two; and ##STR58## Most preferred are the above compounds wherein: R 2 is hydrogen or ##STR59## especially hydrogen; R 3 is hydrogen; n is zero; R 1 is benzyl; and m is two. The compounds of formula I wherein A is ##STR60## are dual inhibitors possessing the ability to inhibit angiotensin converting enzyme and neutral endopeptidase. The compounds of formula I wherein A is ##STR61## are selective inhibitors possessing the ability to inhibit the angiotensin converting enzyme. Thus, all of the compounds of formula I including their pharmaceutically acceptable salts are useful in the treatment of physiological conditions in which angiotensin converting enzyme inhibitors have been shown to be useful. Such conditions include disease states characterized by abnormalities in blood pressure, intraocular pressure, and renin including cardiovascular diseases particularly hypertension and congestive heart failure, glaucoma, and renal diseases such as renal failure. The dual inhibitors are also useful in the treatment of physiological conditions in which neutral endopeptidase inhibitors have been shown to be useful. Such conditions also include cardiovascular diseases particularly hypertension, hyperaldosteronemia, renal diseases, glaucoma, as well as the relief of acute or chronic pain. Thus, the compounds of formula I are useful in reducing blood pressure and the dual inhibitors of formula I are additionally useful for this purpose due to their diuresis and natriuresis properties. The compounds of formula I including their pharmaceutically acceptable salts can be administered for these effects to a mammalian host such as man at from about 1 mg. to about 100 mg. per kg. of body weight per day, preferably from about 1 mg. to about 50 mg. per kg. of body weight per day. The compounds of formula I are preferably administered orally but parenteral routes such as subcutaneous, intramuscular, and intravenous can also be employed as can topical routes of administration. The daily dose can be administered singly or can be divided into two to four doses administered throughout the day. The inhibitors of formula I can be administered in combination with human ANF 99- 126. Such combination would contain the inhibitor of formula I at from about 1 to about 100 mg. per kg. of body weight and the human ANF 99 - 126 at from about 0.001 to about 0.1 mg. per kg. of body weight. The inhibitors of formula I can be administered in combination with other classes of pharmaceutically active compounds. For example, a calcium channel blocker, a potassium channel activator, a cholesterol reducing agent, etc. The inhibitors of formula I or a pharmaceutically acceptable salt thereof and other pharmaceutically acceptable ingredients can be formulated for the above described pharmacetical uses. Suitable compositions for oral administration include tablets, capsules, and elixirs, and suitable compositions for parenteral administration include sterile solutions and suspensions. Suitable compositions for treating glaucoma also include topical compositions such as solutions, ointments, and solid inserts as described in U.S. Pat. No. 4,442,089. About 10 to 500 mg. of active ingredient is compounded with physiologically acceptable vehicle, carrier, excipient, binder, preservative, stabilizer, flavoring, etc., in a unit dose form as called for by accepted pharmaceutical practice. The following examples are illustrative of the invention. Temperatures are given in degrees centigrade. Thin layer chromatography (TLC) was performed in silica gel unless otherwise stated. EXAMPLE 1 [4S-[4α,7α(R*),13bβ]]-1,3,4,6,7,8,13,13b-Octahydro-6-oxo-7-[(2-mercapto-1-oxo-3-phenylpropyl)amino]-2H-pyrido[1',2':1,2]azepino[3,4-b]indole-4-carboxylic acid a) N-Phthalimido-L-tryptophan,dicyclohexylamine salt A slurry of L-tryptophan (15.0 g., 73.4 mmol.) and sodium carbonate (7.785 g, 73.4 mmol.) in water (200 ml.) was stirred at room temperature for 15 minutes, then treated with N-carbethoxyphthalimide (16.098 g., 73.4 mmol.). The non-homogeneous solution became yellow immediately. After stirring for 2 hours, the clear yellow solution was cooled to 0° C. and acidified with 6N hydrochloric acid. The resulting solid was collected by filtration and washed with water. The solid was dissolved in ethyl acetate and washed with water and brine, then dried (sodium sulfate), filtered and stripped to give a yellow oil/foam. The foam was flash chromatographed (Merck silica gel, 5% acetic acid in ethyl acetate) to give the slighly impure desired free acid as a yellow oil. The oil was dissolved in ethyl acetate/ethyl ether and treated with dicyclohexylamine (14.5 ml.) to give pure title compound as a yellow powder (18.955 g.); m.p. 145°-148° (decomp.) TLC: (5% acetic acid in ethyl acetate) R f =0.57. b) N-(N-Phthalimido-L-tryptophyl)-6-hydroxy-L-norleucine, methyl ester Hydrogen chloride gas was bubbled in a slurry of 6-hydroxy-L-norleucine [prepared as described by Bodanszky et al., J. Med. Chem., 21, p. 1030-1035 (1978), 1.00 g., 6.9 mmol.] in dry methanol (35 ml.) until the mixture became homogeneous and began to reflux. The solution was then let cool and was stirred at room temperature for 2.5 hours. The methanol was removed by rotary evaporation and the residue was azeotroped twice with toluene to give crude 6-hydroxy-L-norleucine, methyl ester hydrochloride as a gum. Meanwhile, the dicyclohexylamine salt product from part (a) (3.506 g., 6.8 mmol.) was partitioned between 5% potassium bisulfate and ethyl acetate. The ethyl acetate extract was washed with additional 5% potassium bisulfate and brine, then dried (sodium sulfate), filtered and stripped to give N-phthalimido-L-tryptophan as the free acid. The above crude 6-hydroxy-L-norleucine, methyl ester, hydrochloride was dissolved in dimethylformamide (6 ml.) and methylene chloride (25 ml.) and treated with 4-methylmorpholine (1.30 ml., 1.20 g., 11.8 mmol.). The solution was cooled to 0° C. and treated with N-phthalimido-L-tryptophan followed by hydroxybenzotriazole (925 mg., 6.8 mmol.) and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (1.438 g., 7.5 mmol.). The mixture was stirred at 0° C. for 0.5 hour and then at room temperature for 2.5 hours. The solution was partitioned between ethyl acetate and water and the organic layer was washed successively with 0.5N hydrochloric acid, water, 5% sodium bicarbonate, and brine, then dried (sodium sulfate), filtered and stripped to give 3.06 g., of title product as a yellow foam. TLC: (ethyl acetate) R f =0.35. c) N-(N-Phthalimido-L-tryptophyl)-6-oxo-L-norleucine, methyl ester To a pre-dried (magnesium sulfate) solution of 4-methylmorpholine N-oxide (760 mg., 6.5 mmol.) in methylene chloride (90 ml.) was added the product from part (b) (2.065 g., 4.3 mmol.), dry 4 A molecular sieves (10 g.) and tetrapropyl ammoniumperruthenate (85 mg.). The mixture was stirred at room temperature and was charged with additional tetrapropyl ammoniumperruthenate (35 mg.) after 1, 2, and 3 hours of stirring. After 3.5 hours, the dark mixture was diluted with ethyl acetate and filtered through a short plug of Merck silica gel. The filtrate was stripped and the residue was flash chromatographed (Merck silica gel, 20:80-hexanes:ethyl acetate) to give 1.160 g., of title product as a yellow foam. TLC (ethyl acetate) R f =0.49. d) [4S-[4α,7α,13bβ]]-1,3,4,6,7,8,13,13b-octahydro-6-oxo-7-phthalimido-2H-pyrido[1',2':1,2]azepino[3,4-b]indole-4-carboxylic acid, methyl ester A solution of the product from part (c) (990 mg., 2.08 mmol.) was gently refluxed in a solution of methylene chloride (26 ml.) and trifluoroacetic acid (240 μl.) for 3.5 hours. The cooled solution was washed with saturated sodium bicarbonate, dried (sodium sulfate), filtered and stripped. The residue was flash chromatographed (Merck silica gel, 12% ethyl acetate in methylene chloride) to give a solid. Recrystallization from ethyl ether/methylene chloride afforded 499 mg. of the desired product as a crystalline light yellow solid; m.p. 185° C. (decomp.); [α] D =-117.2° (c=0.8, chloroform). TLC (20% ethyl acetate in methylene chloride) R f =0.39. e) [4S-[4α,7α,13bβ]]-1,3,4,6,7,8,13,13b-Octahydro-7-amino-6-oxo-2H-pyrido[1',2':1,2]azepino[3,4-b]indole-4-carboxylic acid, methyl ester A slurry of the product from part (d) (570 mg., 1.24 mmol.) in methanol (5 ml.) was treated with hydrazine monohydrate (133 μl., 129 mg., 2.6 mmol.). Slight heating was neccessary to effect a homogeneous solution. After stirring at room temperature for 15 hours, the mixture (thick with precipitate) was stirred with 16 ml. of 0.5N hydrochloric acid at 0° C. for 2.5 hours. The solution was filtered and the solid was washed with water. The filtrate was washed with ethyl acetate, made basic with 1N sodium hydroxide and subsequently extracted twice with methylene chloride. The pooled methylene chloride extracts were dried (sodium sulfate), filtered and stripped to afford the product as a solid (145 mg.). The original aqueous insoluble precipitate was partially dissolved in methanol and partitioned with vigorous shaking between ethyl acetate and 0.5N hydrochloric acid. The aqueous layer was separated and made basic with 2N sodium hydroxide and subsequently extracted twice with methylene chloride. The pooled methylene chloride extracts were dried (sodium sulfate), filtered and stripped to give additional desired product (approximately 200 mg.). The isolated solids were pooled, taken up in methylene chloride, concentrated and triturated with ethyl ether to give 319 mg. of title compound as a white solid; m.p. 204°-206° C. (decomp.). [α] D =-30.3° (c=0.5, chloroform). TLC (8:1:1, methylene chloride:acetic acid:methanol) R f =0.35. f) (S)-2-(Acetylthio)benzenepropanoic acid, dicyclohexylamine salt Sodium nitrite (10.3 g., 280 mmol.) was added to a solution of D-phenylalanine (30.0 g., 181 mmol.) and potassium bromide (73.5 g.) in sulfuric acid (2.5N, 365 ml.) over a period of one hour while maintaining the temperature of the reaction mixture at 0° C. The mixture was stirred for an additional hour at 0° C. and then for one hour at room temperature. The reaction solution was extracted with ether, the ether was back extracted with water, and the ether layer was dried over sodium sulfate. Ether was removed in vacuo, and distillation of the oily residue afforded 25.7 g. of (R)-2-bromo-3-benzenepropanoic acid; b.p. 141° (0.55 mm of Hg.); [α] D =+14.5° (c=2.4, chloroform). A mixture of thioacetic acid (7 ml., 97.9 mmol.) and potassium hydroxide (5.48 g., 97.9 mmol.) in acetonitrile (180.5 ml.) was stirred under argon at room temperature for 13/4 hours. The mixture was cooled in an ice-bath, and a solution of (R)-2-bromo-3-benzenepropanoic acid (20.4 g., 89 mmol.) in acetonitrile (20 ml.) was added over a ten minute period. The reaction was stirred under argon at room temperature for 5 hours, filtered, and the acetonitrile was removed in vacuo. The oily residue was redissolved in ethyl acetate and washed with 10% potassium bisulfate and water. Removal of the ethyl acetate in vacuo afforded 19.6 g. of crude product. The crude product was purified via its dicyclohexylamine salt using isopropyl ether as solvent for crystallization. An analytical sample of (S)-2-(acetylthio)benzenepropanoic acid, dicyclohexylamine salt was prepared by recrystallization from ethyl acetate; m.p. 146°-147°; [α] D =-39.6° (c=1.39, chloroform). Anal. calc'd. for C 11 H 12 O 3 S•C 12 H 23 N: C,68.11; H,8.70; N,3.45; S,7.91 Found: C,67.93; H,8.71; N,3.37; S,7.94. g) [4S-[4α,7α(R*),13bβ]]-1,3,4,6,7,8,9,13,13b-Octahydro-7-[[2-(acetylthio)-1-oxo-3-phenylpropyl]amino]-6-oxo-2H-pyrido[1',2':1,2]azepino[3,4-b]indole-4-carboxylic acid, methyl ester The dicyclohexylamine salt from part (f) (450 mg., 1.11 mmol.) was partitioned between ethyl acetate and 5% potassium bisulfate. The ethyl acetate layer was washed with water and brine, then dried (sodium sulfate), filtered and stripped to give the free acid as a colorless oil. A solution of the acid and the product from part (e) (316 mg., 0.965 mmol.) in dry methylene chloride (11 ml.) was treated with triethylamine (149 μl., 108 mg., 1.07 mmol.). The mixture was cooled to 0° C. and subsequently treated with benzotriazol-1-yloxy-tris(dimethylamino) phosphonium hexafluorophosphate (449 mg., 1.02 mmol.). After stirring at 0° C. for 1 hour and at room temperature for 4.5 hours, the mixture was diluted with ethyl acetate and washed successively with 0.5N hydrochloric acid, water, and saturated sodium bicarbonate/brine. The ethyl acetate layer was dried (sodium sulfate), filtered and stripped and the residue was flash chromatographed (Merck silica gel, 65:35-ethyl acetate:hexanes) to give 462 mg. of title product as a white foam. TLC (70:30, ethyl acetate:hexane) R f =0.39. h) [4S-[4α,7α(R*),13bβ]]-1,3,4,6,7,8,13,13b-Octahydro-6-oxo-7-[(2-mercapto-1-oxo-3-phenylpropyl)amino]-2H-pyrido[1',2':1,2]azepino[3,4-b]indole-4-carboxylic acid A solution of the product from part (g) (444 mg., 0.83 mmol.) in methanol (9 ml., deoxygenated via argon bubbling) and tetrahydrofuran (2 ml.) was treated with 1N sodium hydroxide (10 ml., deoxygenated via argon bubbling) and the mixture was stirred at room temperature with argon bubbling. Additional methanol and tetrahydrofuran were added periodically to replace that lost by evaporation. After 1.5 hours, the mixture was acidified with 1N hydrochloric acid (15 ml.), diluted with water, and extracted with ethyl acetate. The ethyl acetate extract was washed with brine, dried (sodium sulfate), filtered, and stripped to give a pale yellow residue. The residue was flash chromatographed (Merck silica gel, 1% acetic acid in ethyl acetate). The fractions containing the desired product were pooled, stripped, and azeotroped twice with ethyl acetate. The resulting oil was dissolved in a small amount of ethyl acetate and ethyl ether and triturated with hexane. The resulting foam was collected by filtration and dried in vacuo to give 266 mg, of title product as a hard white foam; [α] D =+15.9° (c=0.5, chloroform). TLC (1% acetic acid in ethyl acetate) R f =0.39. HPLC: YMC S3 ODS column (6.0×150 mm); eluted with 40% A: 90% water--10% methanol--0.2% phosphoric acid and 60% B: 10% water--90% methanol--0.2% phosphoric acid; flow rate 1.5 ml/min detecting at 220 nm; t R =20.46 min indicates a purity of 96.3%. Anal. calc'd. for C 26 H 27 N 3 O 4 S•0.7 H 2 O: C, 63.71; H, 5.84; N, 8.57; S, 6.54 Found: C, 63.61; H, 5.94; N, 8.23; S, 6.32. EXAMPLE 2 [5S-[5α(R*),8α,11αβ]]-5,6,9,10,11,11a-Hexahydro-5-[(2-mercapto-1-oxo-3-phenylpropyl)amino]-6-oxo-4H,8H-pyrido[1,2-a]thieno[3,2-c]azepine-8-carboxylic acid a) N-Phthalimido-3-(2-thienyl)-L-alanine 3-(2-Thienyl)-L-alanine (2.24 g., 13.1 mmol.) was suspended in water/p-dioxane (20 ml./10 ml.) at room temperature under argon. Sodium carbonate (1.39 g.) was added and the mixture was stirred until homogeneous. N-Carbethoxyphthalimide (2.87 g.) was added, and the resulting mixture was stirred for 4.5 hours and then cooled to 0° C. The pH was adjusted to 1.5 with 6N hydrochloric acid and the mixture was extracted with ethyl acetate. The organic layer was washed successively with 10% potassium bisulfate and brine, dried (sodium sulfate), filtered, and concentrated. The crude product was flash chromatographed (Merck silica gel) eluting with 1:1 ethyl acetate/hexane/1% acetic acid. The fractions containing clean desired product were combined, concentrated, azeotroped with ethyl acetate, and washed with water to remove the acetic acid. The organic layer was dried (sodium sulfate), filtered, and concentrated to give 2.70 g. of the title compound as a white crystalline product; m.p. 166°-168° C.; [α] D =-153.6° (c= 0.46, methylene chloride). TLC (1% acetic acid in 1:1 ethyl acetate/hexane) R f =0.5. b) N-[N-Phthalimido-3-(2-thienyl)-L-alanyl]-6-hydroxy-L-norleucine, methy ester N-Methylmorpholine (1.51 ml., 14.5 mmol.) was added to a solution of 6-hydroxy-L-norleucine, methyl ester, hydrochloride (8.53 mmol.) in methylene chloride (34 ml)/dimethylformamide (9 ml.) at room temperature under argon. The resulting mixture was cooled to 0° C. and N-phthalimido-3-(2-thienyl)-L-alanine (2.57 g., 8.54 mmol.), hydroxybenzotriazole (1.19 g., 8.80 mmol.) and 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (1.80 g., 9.4 mmol.) were added sequentially. After stirring at 0° C. for 30 minutes, the mixture was warmed to room temperature and stirred for 1.5 hours. The volatiles were evaporated and the residue was partitioned between ethyl acetate and water. The organic layer was washed successively with 0.5N hydrochloric acid, water, saturated sodium bicarbonate, and brine, and the organic layer was dried (sodium sulfate), filtered, and concentrated. The residue was flash chromatographed (Merck silica gel) eluting with 2:1 ethyl acetate/hexane to give 3.13 g. of title compound as a white foam. TLC (5% acetic acid in ethyl acetate) R f =0.68. c) N-[N-Phthalimido-3-(2-thienyl)-L-alanyl]-6-oxo-L-norleucine, methyl ester To a solution of 4-methylmorpholine N-oxide (1.12 g., 9.6 mmol., pre-dried over magnesium sulfate) and the product from part (b) (2.83 g., 6.37 mmol.) was added 4A molecular sieves and tetrapropyl ammoniumperruthenate (200 mg.). The resulting mixture was stirred for 2 hours at room temperature. The mixture was filtered through Celite and the volatiles were evaporated. The residue was flash chromatographed (Merck silica gel) eluting with 1:1 ethyl acetate/hexane to give 1.54 g. of title compound as white crystals; m.p. 125°-126° C.; [α] D =-70.3° (c=0.46, methylene chloride). TLC (1:1, ethyl acetate/hexane) R f =0.27. d) (S)-1-[N-Phthylimido-3-(2-thienyl)-L-alanyl]-4-tetrahydro-2-pyridinecarboxylic acid, methyl ester Trifluoroacetic acid (73 μl.) was added to a solution of the product from part (c) (1.53 g., 3.45 mmol.) in methylene chloride (36 ml.) at room temperature under argon. The mixture was gently refluxed for 3.5 hours. After cooling to room temperature, the mixture was washed with 50% saturated sodium bicarbonate, dried (sodium sulfate), filtered, and concentrated. The residue was flash chromatographed (Merck silica gel) eluting with 2:1 hexane/ethyl acetate to give 1.22 g. of title compound as a white foam. TLC (3:2, hexane/ethyl acetate) R f =0.42. e) [5S-[5α,8α,11αβ]]-5,6,9,10,11,11a-Hexahydro-6-oxo-5-phthalimido-4H,8H-pyrido[1,2-a]thieno[3,2-c]azepine-8-carboxylic acid, methyl ester The product from part (d) (1.16 g., 2.74 mmol.) was dissolved in methylene chloride (35 ml.) at room temperature under argon. Trifluoromethanesulfonic acid (1.82 ml.) was added and the resulting mixture was stirred for 1 hour. The mixture was poured into ice water and extracted with ethyl acetate. The organic layer was washed with brine, dried (sodium sulfate), filtered and concentrated to give 1.1 g of a yellow solid-like residue. The residue was dissolved in methylene chloride (8 ml.)/methanol (10 ml.) and cooled to 0° C. The mixture was treated with excess diazomethane for 5 minutes. The excess diazomethane was destroyed with acetic acid and the volatiles were removed. The yellow residue was flash chromatographed (Merck silica gel) eluting with 2:1 hexane/ethyl acetate to give 720 mg. of a white crystalline product. Recrystallization from hot ethyl acetate/hexane gave 670 mg. of analytically pure title compound; m.p. 163.5°-164° C.; [α] D =-119.5° (c=0.43, methylene chloride). TLC (2:1, hexane/ethyl acetate) R f =0.15. f) [5S-[5α,8α,11αβ]]-5,6,9,10,11,11a-Hexahydro-5-amino-6-oxo-4H,8H-pyrido[1,2-a]thieno[3,2-c]azepine-8-carboxylic, methyl ester The product from part (e) (670 mg., 1.58 mmol.) was suspended in methanol (8 ml.) at room temperature under argon. The mixture was treated with hydrazine monohydrate (0.17 ml.), became homogeneous, and was stirred for 16 hours. The mixture was filtered to remove the white precipitate and the filtrate was stripped, treated with methylene chloride, filtered and stripped again to give a white crystalline solid. The solid was recrystallized from hot ethyl acetate and hexane to give 372 mg. of title compound as white needle-like crystals; m.p. 151°-154° C.; [α] D =-20.9° (c=0.47, methylene chloride). TLC (4% methanol in methylene chloride) R f =0.39. g) [5S-[5α(R*),8α,11αβ]]-5,6,9,10,11.11a-Hexahydro-5-[[2-(acetylthio)-1-oxo-3-phenylpropyl]amino]-6-oxo-4H,8H-pyrido[1,2-a]thieno[3,2-c]azepine-8-carboxylic acid, methyl ester (S)-2-(Acetylthio)benzenepropionic acid, dicyclohexylamine salt (589 mg., 1.45 mmol.) was partitioned between ethyl acetate and 10% potassium bisulfate. The organic layer was washed with brine, dried (sodium sulfate), filtered, and concentrated to give (S)-2-(acetylthio) benzenepropanoic acid as an oil. The residue was dissoved in methylene chloride (15 ml.) at room temperature under argon. Following the addition of the product from part (f) (371 mg., 1.26 mmol.), the mixture was cooled to 0° C. and triethylamine (0.19 ml., 1.39 mmol.) was added. The resulting mixture was stirred for 5 minutes then benzotriazol-1-yloxytris(dimethylamino)phosphonium hexafluorophosphate (585 mg., 1.32 mmol.) was added. After being stirred at 0° C. for 1 hour, the reaction mixture was warmed to room temperature and was stirred for 16 hours. The volatiles were evaporated and the residue was dissolved in ethyl acetate and washed successively with 1N hydrochloric acid, water, 50% saturated sodium bicarbonate, and brine. The organic layer was dried (sodium sulfate), filtered, and concentrated and the residue was flash chromatographed (Merck silica gel) eluting with 3:2 hexane/ethyl acetate to give 508 mg. of the desired product as a white foam. TLC (1:1, ethyl acetate/hexane) R f =0.64. h) [5S-[5α(R*),8α,11αβ]]-5,6,9,10,11,11a-Hexahydro-5-[(2-mercapto-1-oxo-3-phenylpropyl)amino]-6-oxo-4H,8H-pyrido[1,2-a]thieno[3,2-c]azepine-8-carboxylic acid A solution of the product from part (g) (496 mg., 1.1 mmol.) in methanol (10 ml., deoxygenated via argon bubbling) was cooled to 0° C. and treated with 1N sodium hydroxide (8 ml., deoxygenated via argon bubbling). The resulting mixture was stirred under argon for 1 hour. The mixture was warmed to room temperature and stirred an additional 2.5 hours. The mixture was acidified with 10% potassium bisulfate and extracted with ethyl acetate. The organic layer was washed successively with water and brine, dried (sodium sulfate), filtered and concentrated to give a yellow oil. This residue was flash chromatographed (Merck silica gel) eluting with 1% acetic acid in 3:2 hexane/ethyl acetate. The fractions containing pure product were combined, concentrated, azeotroped with ethyl acetate, and washed with water to remove any acetic acid. The organic layer was dried (sodium sulfate), filtered and concentrated. The residue was taken up in ethyl acetate and triturated with hexane. The solvent was removed and the residue was slurried in hexane, stripped, and dried in vacuo to give 416 mg. of title product as a white powdery foam; [α] D =+24.0° (c=0.52, methanol). TLC (2% acetic acid in ethyl acetate) R f =0.84. HPLC: YMC S-3 ODS (C-18) 6.0×150 mm; 64% (10% water--90% methanol--0.2% phosphoric acid)/36 % (90% water--10% methanol--0.2% phosphoric acid), flow rate=1.5 ml/min, isocratic, detecting at 220 nm; t R =11.8 min. indicates a purity of 95%. Anal. calc'd. for C 22 H 24 N 2 O 4 •0.8 water•0.25 hexane•0.25 ethyl acetate C, 58.55; H, 6.24; N, 5.57; S, 12.76; Found C, 58.55; H, 5.88; N, 5.64; S, 12.56. EXAMPLE 3 [5S-[5α(R*),8α,11αβ]]-5,6,9,10,11,11a-Hexahydro-5-[(2-mercapto-1-oxo-3-phenylpropyl)amino]-6-oxo-4H,8H-pyrido[1,2-a]thieno[2,3-c]azepine-8-carboxylic acid a) N-Phthalimido-3-(3-thienyl)-L-alanine 3-(3-Thienyl)-L-alanine (2.45 g., 14.3 mmol.) was suspended in water/p-dioxane (22 ml/11 ml.) at room temperature under argon. Sodium carbonate (1.52 g.) was added and the mixture was stirred until homogeneous. N-Carbethoxyphthalimide (3.14 g.) was added, and the resulting mixture was stirred for 3.0 hours and then cooled to 0° C. The pH was adjusted to 1.5 with 6N hydrochloric acid and the mixture was extracted with ethyl acetate. The organic layer was washed successively with 10% potassium bisulfate and brine, dried (sodium sulfate), filtered, and concentrated. The crude product was flash chromatographed (Merck silica gel) eluting with 1:1 ethyl acetate/hexane/1% acetic acid. The fractions containing clean desired product were combined, concentrated, azeotroped with ethyl acetate, and washed with water to remove the acetic acid. The organic layer was dried (sodium sulfate), filtered, and concentrated to give 3.22 g. of title compound as a white crystalline product; m.p. 166°-168° C.; [α] D =-146.8° (c=0.46, methylene chloride). TLC (1% acetic acid in 1:1 ethyl acetate/hexane) R f =0.31. b) N-[N-Phthalimido-3 -(3-thienyl)-L-alanyl]-6-hydroxy-L-norleucine, methyl ester N-Methylmorpholine (1.89 ml., 18.12 mmol.) was added to a solution of 6-hydroxy-L-norleucine, methyl ester, hydrochloride (10.66 mmol.) in methylene chloride (41 ml.)/dimethylformamide (11 ml.) at room temperature under argon. The resulting mixture was cooled to 0° C. and N-phthalimido-3-(3-thienyl)-L-alanine (3.21 g., 10.66 mmol.), hydroxy-benzotriazole (1.48 g., 10.98 mmol.), and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (2.25 g., 11.73 mmol.) were added sequentially. After stirring at 0° C. for 30 minutes, the mixture was warmed to room temperature and stirred for 2 hours. The volatiles were evaporated and the residue was partitioned between ethyl acetate and water. The organic layer was washed successively with 0.5N hydrochloric acid, water, saturated sodium bicarbonate, and brine, and the organic layer was dried (sodium sulfate), filtered, and concentrated. The residue was flash chromatographed (Merck silica gel) eluting with 4:1 ethyl acetate/hexane to give 3.8 g. of title compound as a white foam. TLC (ethyl acetate) R f =0.56. c) N-[N-phthalimido-3-(3-thienyl)-L-alanyl]-6-oxo-L-norleucine, methyl ester Oxalyl chloride (0.84 ml., 9.78 mmol.) was added to a flask containing methylene chloride (40 ml.) at -78° C. under argon. Following the dropwise addition of dimethylsulfoxide (1.39 ml., 19.56 mmol.) in methylene chloride (2 ml.), the mixture was stirred for 20 minutes. A solution of the product from part (b) (3.62 g., 8.15 mmol.) in methylene chloride (20 ml.) was added, the mixture was stirred for 15 minutes, triethylamine (7.0 ml.) was added, and the mixture was stirred for 5 minutes. After warming to room temperature, the mixture was partitioned between ethyl acetate and 0.5N hydrochloric acid and the organic layer was washed with brine, dried (sodium sulfate), filtered, and concentrated to obtain white crystals. The crystals were triturated with ethyl ether and collected by filtration to give 3.04 g. of title compound; m. p. 102°-104° C.; [α] D =-58.0° (c=0.68, methylene chloride). TLC (ethyl acetate) R f = 0.83. d) (S)-1-[N-phthalimido-3-(3-thienyl)-L-alanyl]-4-tetrahydro-2-pyridinecarboxylic acid, methyl ester Trifluoroacetic acid (0.15 ml.) was added to a solution of the product from part (c) (3.02 g., 6.83 mmol.) in methylene chloride (70 ml.) at room temperature under argon. The mixture was gently refluxed for 3 hours. After cooling to room temperature, the mixture was washed with 50% saturated sodium bicarbonate, dried (sodium sulfate), filtered, and concentrated. The residue was flash chromatographed (Merck silica gel) eluting with 3:2 hexane/ethyl acetate to give 2.49 g. of title compound as a white foam. TLC (3:2, hexane/ethyl acetate) R f =0.44. e) [5S-[5α,8α,11αβ]]-5,6,9,10,11,11a-Hexahydro-6-oxo-5-phthalimido-4H,8H-pyrido[1,2-a]thieno[2,3-c]azepine-8-carboxylic acid, methyl ester The product from part (d) (2.29 g., 5.40 mmol.) was dissolved in methylene chloride (70 ml.) at room temperature under argon. Trifluoromethanesulfonic acid (3.6 ml.) was added and the resulting mixture was stirred for 0.5 hour. The mixture was poured into ice water and extracted with ethyl acetate. The organic layer was washed with brine, dried (sodium sulfate), filtered and concentrated to give a dark orange oil. The residue was dissolved in methylene chloride (15 ml.)/methanol (20 ml.) and cooled to 0° C. The mixture was treated with excess diazomethane for 5 minutes. The excess diazomethane was destroyed with acetic acid and the volatiles were removed. The residue was flash chromatographed (Merck silica gel) eluting with 1:1 hexane/ethyl acetate to give 441 mg. of title compound as a white crystalline product; m.p. 132°-134° C.; [α] D =-87.4° (c=0.47, methylene chloride). TLC (1:1, hexane/ethyl acetate) R f =0.5. f) [5S-[5α,8α,11αβ]]-5,6,9,10,11,11a-Hexahydro-5-amino-6-oxo-4H,8H-pyrido[1,2-a]thieno[2,3-c]azepine-8-carboxylic acid, methyl ester The product from part (e) (370 mg., 0.87 mmol.) was suspended in methanol (8 ml.) at room temperature under argon. After methylene chloride (4 ml.) was added to effect a homogeneous mixture, the mixture was treated with hydrazine monohydrate (0.09 ml., 1.92 mmol., 2.2 equiv.) and was stirred for 1.5 hours. The volatiles were evaporated and the residue was chased with toluene (×2). The residue was redissolved in methanol and stirred at room temperature for 72 hours. The mixture was filtered to remove the white precipitate and the filtrate was stripped, treated with methylene chloride, filtered and stripped again to give 300 mg. of title product as a yellow oil. TLC (4% methanol in methylene chloride) R f =0.63. g) [5S-[5α(R*),8α,11αβ]]-5,6,9,10,11,11a-Hexahydro-5-[[2-(acetylthio)-1-oxo-3-phenylpropyl]amino]-6-oxo-4H-8H-pyrido[1,2-a]thieno[2,3-c]azepine-8-carboxylic acid, methyl ester (S)-2-(Acetylthio)benzenepropanoic acid, dicyclohexylamine salt (406 mg., 1.0 mmol.) was partitioned between ethyl acetate and 10% potassium bisulfate. The organic layer was washed with brine, dried (sodium sulfate), filtered, and concentrated to give (S)-2-(acetylthio)benzenepropanoic acid as an oil. The residue was dissoved in methylene chloride (10 ml.) at room temperature under argon. Following the addition of the product from part (f) (0.87 mmol.), the mixture was cooled to 0° C. and triethylamine (0.13 ml., 0.96 mmol.) was added. The resulting mixture was stirred for 5 minutes then benzotriazol-1-yloxytris(dimethylaminopropyl)phosphonium hexafluorophosphate (403 mg., 0.91 mmol.) was added. After being stirred at 0° C. for 1 hour, the reaction mixture was warmed to room temperature and was stirred for 16 hours. The volatiles were evaporated and the residue was dissolved in ethyl acetate and washed successively with 1N hydrochloric acid, water, 50% saturated sodium bicarbonate, and brine. The organic layer was dried (sodium sulfate), filtered, and concentrated and the residue was flash chromatographed (Merck silica gel) eluting with 3:2 hexane/ethyl acetate to give 367 mg. of the desired product as a yellow oil. TLC (1:1, ethyl acetate/hexane) R f =0.52. h) [5S-[5α(R*),8α,11αβ]]-5,6,9,10,11,11a-Hexahydro-5-[(2-mercapto-1-oxo-3-phenylpropyl)amino]-6-oxo-4H,8H-pyrido[1,2-a]thieno[2,3 -c]azepine-8-carboxylic acid A solution of the product from part (g) (365 mg., 0.78 mmol.) in methanol (8 ml., deoxygenated via argon bubbling) was cooled to 0° C. and treated with 1N sodium hydroxide (6 ml., deoxygenated via argon bubbling). The resulting mixture was stirred under argon for 0.5 hour. The mixture was warmed to room temperature and stirred an additional 4.5 hours. The mixture was acidified with 10% potassium bisulfate and extracted with ethyl acetate. The organic layer was washed successively with water and brine, dried (sodium sulfate), filtered and concentrated to give a yellow oil. This residue was flash chromatographed (Merck silica gel) eluting with 1% acetic acid in 3:2 hexane/ethyl acetate. The fractions containing pure product were combined, concentrated, azeotroped with ethyl acetate, and washed with water to remove any acetic acid. The organic layer was dried (sodium sulfate), filtered and concentrated. The residue was taken up in ethyl acetate and triturated with hexane. The solvent was removed and the residue was slurried in hexane, stripped, and dried in vacuo to give 310 mg.of title compound as a white powdery foam; [α] D =+29.8° (c=0.38, methylene chloride). TLC (2% acetic acid in ethyl acetate) R f =0.82. HPLC: YMC S-3 ODS (C-18) 6.0×150 mm; 65% (10% water--90% methanol--0.2% phosphoric acid)/35% (90% water--10% methanol--0.2% phosphoric acid), flow rate=1.5 ml/min, isocratic, detecting at 220 nm; t r =11.9 min indicates a purity of 99.2% Anal. calc'd. for C 22 H 24 N 2 O 4 S 2 •1.0 H 2 O: C, 57.05; H, 5.67; N, 6.05; S, 13.84; Found C, 57.15; H, 5.56; N, 5.95; S, 13.30. EXAMPLE 4 1000 tablets each containing the following ingredients: ______________________________________[5S-[5α(R*),8α,11aβ]]-5,6,9,10,11,11a- 200 mg.Hexahydro-5-[(2-mercapto-1-oxo-3-phenylpropyl)amino]-6-oxo-4H,8H-pyrido[1,2-a]thieno[2,3-c]azepine-8-carboxylic acidCornstrach 100 mg.Gelatin 20 mg.Avicel(microcrystalline cellulose) 50 mg.Magnesium stearate 5 mg. 375 mg.______________________________________ are prepared from sufficient bulk quantities by mixing the product of Example 3 and cornstarch with an aqueous solution of the gelatin. The mixture is dried and ground to a fine powder. The Avicel and then the magnesium stearate are admixed with granulation. The mixture is then compressed in a tablet press to form 1000 tablets each containing 200 mg. of active ingredient. In a similar manner, tablets containing 200 mg. of the product of Examples 1 or 2 can be prepared. Similar procedures can be employed to form tablets or capsules containing from 50 mg. to 500 mg. of active ingredient.

Compounds of the formula ##STR1## wherein A is ##STR2## are useful as ACE and NEP inhibitors and those wherein A is ##STR3## are useful as ACE inhibitors. Methods of preparation and intermediates are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of U.S. patent application Ser. No. 12/822,281 filed Jun. 24, 2010, now U.S. Pat. No. 8,059,916, which is a division of U.S. patent application Ser. No. 11/675,236, filed Feb. 15, 2007 now U.S. Pat. No. 7,773,827, which claims the benefit of U.S. Provisional application Ser. No. 60/773,419, filed Feb. 15, 2006. All of the aforementioned applications are incorporated herein by reference. BACKGROUND AND SUMMARY OF THE INVENTION The present invention relates to projection systems where multiple projectors are utilized to create respective complementary portions of a projected image, which may be a video or still image. More particularly, the present invention relates to methods of calibrating and operating such systems. According to one embodiment of the present invention, a method of calibrating a multi-projector image display system is provided. According to the method, non-parametric calibration data for the display system is recovered and used to generate a non-parametric mapping of positions in each projector to their position within a common global reference frame of the display system. Local parametric models that relate to the display surface are generated using a canonical description that either represents the image projection screen or the expected position of neighboring points when projected onto the screen. In addition, these local parametric models may represent the expected position of points in one device, e.g., a projector, when they are known in a second device, e.g., a camera. These local parametric models are compared with data points defined by the non-parametric calibration data to identify one or more local errors in the non-parametric calibration data. The local errors in the non-parametric calibration data are converted to data points by referring, at least in part, to the local parametric models. Although the conversion may be solely a function of the parametric model, it is contemplated that the conversion may be a function of both the parametric model and the non-parametric mapping, e.g., by referring to the predicted data points given by the parametric models and measurements taken from the non-parametric mapping. The projectors are operated to project an image on the image projection screen by utilizing a hybrid calibration model comprising data points taken from the non-parametric model and data points taken from one or more local parametric models. In accordance with another embodiment of the present invention, a method of operating a multi-projector display system is provided. According to the method, the display system is operated according to an image rendering algorithm that incorporates a hybrid parametric/non-parametric calibration model. In accordance with another embodiment of the present invention, a method of calibrating an image display system is provided. The system comprises a plurality of projectors oriented in the direction of an image projection screen and at least one calibration camera. According to the method, the calibration camera captures k distinct images of the image projection screen. All projectors contributing to each captured image render a set of fiducials captured by the calibration camera. A set of three-dimensional points corresponding to camera image points are computed as respective intersections of back-projected rays defined by the points and a canonical surface approximating the projection screen. The points are matched with projected fiducials to generate a set of corresponding match points. The set of three-dimensional points observed in different camera views are represented as a set of 3D surface points with a known neighborhood function. The 3D points are modeled as a constraint system such that the error distance between two points seen in two different camera views are computed as the geodesic distance between the first point, as seen in the second view, and the second point, as seen in that same view. Points that correspond to the same projector location but have different locations on the 3D surface are adjusted according to an error metric that minimizes the total error represented in the constraint system. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS The following detailed description of specific embodiments of the present invention can be best understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which: FIGS. 1 and 2 are schematic illustrations of an image projection system that may be calibrated according to the methodology of the present invention; and FIG. 3 is a flow chart illustrating a calibration method according to one embodiment of the present invention. DETAILED DESCRIPTION Generally, various embodiments of the present invention relate to calibration techniques that utilize local parametric models in conjunction with global non-parametric models. Although the calibration methodology of the present invention has broad applicability to any image projection system where an image or series of images are projected onto a viewing screen, the methodology of the various embodiment of the present invention are described herein in the context of a complex-surface multi-projector display system referred to as the Digital Object Media Environment (DOME). Referring to FIGS. 1 and 2 , the DOME 10 is composed of a vacuum-shaped back projection screen 20 that is illuminated by a cluster of projectors 30 (P 1 -P 4 ) mounted below the projection surface in a mobile cabinet 40 . Each projector 30 is connected to a projection controller 50 , which may comprise a single computer or a series of personal computers linked via an Ethernet cable or other suitable communications link. The controller 50 provides each projector with rendered images that contribute to the image display. A pan-tilt camera 60 is mounted within the DOME cabinet and is used in the calibration processes described herein. User head-positions are tracked via one or more wireless optical head-tracking units 70 or other suitable head-tracking hardware mounted to the DOME device 10 . Head tracking enables the user 80 to move their head or body through the computer generated scene while the image 90 is continually updated to reflect the user's current eye positions. Given the dynamic head position of each user, the projectors can be controlled to generate images 90 that will synchronously provide users with the perception that the object being visualized is situated within the spherical DOME surface 20 . Referring to FIG. 1 , at each instant a ray P v that passes from the center of projection of the user 80 to a point on the image 90 intersects the spherical surface 20 and defines what color should be projected at that point on the spherical DOME surface 20 . System calibration determines what projector and ray P p is required to illuminate the point. Once calibrated, the projectors 30 and the controller 50 cooperate to render distinct images for both users 80 . The DOME system 10 can be self-contained in a rolling cabinet that can be moved from one room to the next. Although the illustrated embodiment utilizes four projectors to illuminate a display surface that is approximately 32 inches in diameter, the calibration and rendering principles introduced herein are equally applicable to displays of different resolutions and sizes and display surfaces of arbitrary shape. Referring now to the flow chart of FIG. 3 , data regarding the geometry of the projection screen 20 and the respective geometric positions of the projectors 30 are input to initialize the illustrated calibration routine (see steps 100 , 102 ). Non-parametric calibration data is then recovered utilizing the input data (see step 104 ) and is used to generate a non-parametric model of the display system (see step 106 ) that maps points in each projector to points in a global display space. Non-parametric calibration data may be recovered in a variety of ways. For example, and not by way of limitation, when projecting onto an irregular surface, or when the projector optics induce radial distortion in the projected image, the resulting image warp can be described as a point-wise map, e.g., a lookup table, encoding the projected positions of projected pixels on a pixel-wise basis or as a surface mesh whose vertices are points in the global display space that correspond to observations and whose edges represent adjacency. For the purposes of defining and describing the present invention, it is noted that data recovery should be read broadly enough to cover construction, calculation, generation, retrieval, or other means of obtaining or creating this non-parametric mapping of projector pixels to a common coordinate system. Once the non-parametric model has been established (see step 106 ), canonical surface data is used to apply local parametric models to the global, non-parametric calibration data (see steps 108 , 110 ). In this manner, the inherent uniformity of the local parametric models can be used to correct local artifacts and other discontinuities generated by the global, non-parametric calibration data. Broader application of the local parametric models is discouraged here because, although the parametric calibration data helps guarantee smooth calibration across the projector field by minimizing local irregularities within a single projector, global parametric solutions are typically ineffective between adjacent projectors and can lead to abrupt geometric discontinuities at projector edges. In addition, strict adherence to a parametric model often requires that the model be correct and in correspondence with the display surface over a large area, while multiple, local models typically only need to describe how points relate to one another locally. The calibration scheme illustrated in FIG. 3 is a fundamentally non-parametric system that incorporates parametric constraints in local regions to detect and correct non-smooth areas in the calibration map. As is noted above, the calibration routine generally proceeds in two stages. First, the non-parametric calibration data is recovered (see step 106 ). This data is globally accurate, but subject to some local perturbances due to image processing, display non-uniformity, or other artifacts. The non-parametric phase of model acquisition determines a mapping from each projector pixel to its corresponding position in a common coordinate system. Typically, the parametric models are only applied once projector pixels have been mapped to a common, global space. Once this global, non-parametric model has been acquired (see step 108 ), the local parametric models are applied over local regions (see step 110 ). If the observed, non-parametric model differs significantly from the predicted, parametric model, individual points are identified as local errors (see step 112 ). These local errors are eliminated from the non-parametric model by replacing the perturbed local data points within the non-parametric model with a corresponding point generated by the parametric model (see step 114 ). This replacement step can include, but is not limited to, a straightforward evaluation of the parametric model at an interpolated point or some weighted contribution of the observed point and the point implied by the parametric model. By using the parametric model independently, in small regions, the global problems typically associated with parametric calibration data is avoided, while retaining the local consistency that the parametric model provides. Calibration results can be verified by generating a calibration image that is configured such that errors in the hybrid calibration routine can be readily identified by a user 80 or one or more image analysis cameras when the image is displayed on the projection screen. For example, and not by way of limitation, the calibration image may be constructed as a 3D mesh and displayed on the projection screen 20 . An example of the use of a suitable mesh is described in detail below with reference to the multi-projector system 10 illustrated in FIGS. 1 and 2 . Thus, in the multi-projector calibration scheme illustrated in FIG. 3 , each projector pixel is registered to a canonical surface that can approximate the actual display surface. Local perturbations of these mappings account for deviations from the canonical surface. These perturbations, which can arise from screen surface abnormalities, error in the estimated camera position, and differences in the canonical model and true display shape, are classified as local errors and are corrected by replacing perturbed local data points within the non-parametric model with a corresponding point generated by the parametric model. Likewise, a new point can be generated through a weighted combination of the point predicted by the local parametric model and the existing data point. This approach is motivated by the observation that local errors, i.e., discontinuities in the projected image where none exists on the projection surface, are far more problematic than global, correlated errors. For example, and not by way of limitation, in the multi-projector system 10 illustrated in FIGS. 1 and 2 , a hemisphere is the canonical model, but the true shape of the display surface is a hemisphere intersected with a cone. The pan-tilt camera 60 actuates to several overlapping view positions to capture k distinct images such that all points on the display surface 20 are seen in at least one image. For each camera position, all visible projectors 30 (P 1 -P 4 ) render a set of Gaussian fiducials that are then captured in the camera 60 . Using binary encoding techniques, the observed fiducials are matched with projected targets to generate a set of corresponding match points. For a given pan-tilt position k, the translation [xyz] C T and rotation parameters of the camera 60 are computed from an estimated initial position of the camera in the world reference frame. The camera intrinsics, M are recovered before the camera 60 is placed in the DOME 10 and are then coupled with each view position to derive a complete projection matrix: P k = M ⁡ [ e 1 · r 1 k e 1 · r 2 k e 1 · r 3 k - R 1 T ⁢ T x e 2 · r 1 k e 2 · r 2 k e 2 · r 3 k - R 2 T ⁢ T y e 3 · r 1 k e 3 · r 2 k e 3 · r 3 k - R 3 T ⁢ T z 0 0 0 1 ] ⁢ C w p where e i are the basis vectors of the estimated coordinate system for the camera 60 in the pan-tilt reference frame, r i k are the basis vectors for pan-tilt frame at position k, and T is the estimated offset from camera to pan-tilt. R i is the i th column of the upper left 3×3 rotation components of the transform matrix. Finally, Cω P is the coordinate system change from world, i.e., from where the canonical surface is defined to the estimated frame of the pan-tilt camera 60 . Given the assumption that observed points in the camera plane arise from projected fiducials on the canonical surface, then the three-dimensional point [x y z] T corresponding to image point (i, j) k is computed as the intersection of the canonical surface with the back-projected ray defined by the point and focal length f, P k -1 [0001] T +λP k -1 [ijf1] T . Preferably, the observed match points are back-projected prior to evaluation and application of the parametric model. Because the canonical surface in the case of the DOME 10 is a hemisphere, the center of a match point in the projector frame p p can be related to a corresponding point in the camera p c via a second degree polynomial, e.g., p c =P(p p ). This locally parametric model can be used to eliminate invalid match points and dramatically increase the robustness of the calibration phase. The locally parametric model is only used to eliminate potentially noisy match points and does not typically play a role in global calibration. The nine parameters of P can be recovered via a robust least squares fit, for a given match point over a 5×5 grid of neighboring points. Typically, the match point under consideration is not used during the fit. Instead, the distance between the match point and the fit model P is measured and if this distance exceeds some threshold, the match point is considered to be in error, and is discarded. The local parametric model is then used to interpolate a new match point at this location. This set of three-dimensional points observed in different camera views must be registered to a single three-dimensional point cloud. If the same projector point is seen in multiple views only one is selected by iterating through multiple camera views and adding only unique points until the point cloud is fully populated. Next, a 3D Deluanay triangulation is performed on this point cloud to compute neighbor relations. Finally, this 3D mesh is modeled as a constraint system in which each edge is assigned a weight of one and a length, i.e., an error distance, that corresponds to the separation of the two points on the sphere. In the case when two points arise from the same camera view, the distance is equivalent to the geodesic distance. However, if the two points p k 1 and p l 2 are seen in two different camera views, the distance between the two points D(p k 1 , p l 2 ) is computed as D(p l 1 , p l 2 ), i.e., the geodesic distance between the first point p l 1 , as seen in the second view, and the second point p l 2 as seen in that same view. Following error distance assignments, the constraint model is relaxed in order to minimize the total error contained in the constraint system. This minimization phase may use a variety of minimization techniques including traditional gradient, downhill simplex, simulated annealing, or any other conventional or yet to be developed energy minimization technique. As a result, local errors are distributed over the mesh, including those arising from error propagation between views, error in estimated camera positions, improperly modeled radial distortion, etc. This yields a perceptually consistent calibration across all projectors 30 . Once the projectors 30 have been calibrated, a cooperative rendering algorithm then generates a frame-synchronized image for each user's head position. Although the projectors could be dynamically assigned to each viewer 80 based on their relative head positions, it is often sufficient to partition the set of pixels into two distinct views that illuminate opposite sides of the spherical DOME surface 20 . In this manner, each user 80 can see a correct view of the model being visualized for collaborative purposes. Image rendering may be controlled in a variety of conventional or yet-to-be developed ways, including those where two-pass algorithm is utilized to estimate the projection surface automatically. At each frame, the head-positions of the viewers 80 are determined via the head-tracking units 70 and then distributed to individual projection clients or to an integrated controller 50 emulating the clients via a multi-cast signal over a local network or other communications link Each rendering client then generates an image of the object from the viewpoint of the current head-position. The rendered view for each projector 30 is then registered with the global coordinate system by back-projecting the rendered frame buffer onto the display surface 20 . This can, for example, be accomplished via projective texture mapping or any other suitable projection routine. Finally, it is contemplated that intensity blending can be incorporated into the projection routine by using traditional multi-projector blending or modified multi-projector blending routines including, for example, those that utilize a distance metric computed on the sphere. It is noted that recitations herein of a component of the present invention being “configured” to embody a particular property, function in a particular manner, etc., are structural recitations, as opposed to recitations of intended use. More specifically, the references herein to the manner in which a component is “configured” denotes an existing physical condition of the component and, as such, is to be taken as a definite recitation of the structural characteristics of the component. It is noted that terms like “preferably,” “commonly,” and “typically” are not utilized herein to limit the scope of the claimed invention or to imply that certain features are critical, essential, or even important to the structure or function of the claimed invention. Rather, these terms are merely intended to highlight alternative or additional features that may or may not be utilized in a particular embodiment of the present invention. Having described the invention in detail and by reference to specific embodiments thereof, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims. More specifically, although some aspects of the present invention are identified herein as preferred or particularly advantageous, it is contemplated that the present invention is not necessarily limited to these preferred aspects of the invention. For example, although the calibration methodology of the present invention has been described herein in the context of a complex-surface multi-projector display system referred to as the Digital Object Media Environment (DOME), the appended claims should not be limited to use with the DOME or similar projection systems unless they expressly recite the DOME.

A method of calibrating a multi-projector image display system is provided. According to the method, non-parametric calibration data for the display system is recovered and used to generate a non-parametric model of the display system. Local parametric models relating to the display surface of the projection screen are generated and are compared with data points defined by the non-parametric calibration data to identify one or more local errors in the non-parametric calibration data. The local errors in the non-parametric calibration data are converted to data points defined at least in part by the local parametric models and the projectors are operated to project an image on the image projection screen by utilizing a hybrid calibration model comprising data points taken from the non-parametric model and data points taken from one or more local parametric models. Additional embodiments are disclosed and claimed.

BACKGROUND Technical Field [0001] The present disclosure generally relates to evaluating items in product specification data sets with respect to reference data that enables context-specific comparisons of the data sets. Description of the Related Art [0002] Commodity items such as lumber, agricultural products, metals, and livestock/meat are usually traded in the open market between a number of buyers and sellers. The sales transactions of most commodity items involve a number of parameters. For instance, in the trade of commodity lumber, a buyer usually orders materials by specifying parameters such as lumber species, grade, size (i.e., 2×4, 2×10, etc.), and length, as well as the “tally” or mix of units of various lengths within the shipment, method of transportation (i.e., rail or truck), shipping terms (i.e., FOB or delivered), and desired date of receipt, with each parameter influencing the value of the commodity purchase. Given the multiple possible combinations of factors, a commodity buyer often finds it difficult to objectively compare similar but unequal offerings among competing vendors. [0003] For example, in a case where a lumber buyer desires to order a railcar load of spruce (SPF) 2×4's of #2 & Better grade, the buyer would query vendors offering matching species and grade carloads seeking the best match for the buyer's need or tally preference at the lowest market price. Lumber carloads are quoted at a price per thousand board feet for all material on the railcar. When the quoted parameters are not identical, it is very difficult for buyers to determine the comparative value of unequal offerings. [0004] Typically, a lumber buyer will find multiple vendors each having different offerings available. For example, a railcar of SPF 2×4's may be quoted at a rate of $300/MBF (thousand board feet) by multiple vendors. Even though the MBF price is equal, one vendor's carload may represent significantly greater marketplace value because it contains the more desirable lengths of 2×4's, such as market-preferred 16-foot 2×4's. When the offering price varies in addition to the mix of lengths, it becomes increasingly difficult to compare quotes from various vendors. Further, because construction projects often require long lead times, the lumber product may need to be priced now, but not delivered until a time in the future. Alternately, another species of lumber (i.e., southern pine) may represent an acceptable substitute. [0005] Therefore, from the foregoing, there is a need for a method and system that allows users to evaluate and effectively compare items having different attributes to optimize decision making with regard to such items. BRIEF SUMMARY [0006] The present disclosure is directed, at least in part, to configuring a product specification data set and evaluating alternative configurations. In various embodiments, the system automatically provides one or more context-specific reference data values for a product specification data set as configured by a user-agent. The disclosure also includes, in part, automatically updating context-specific reference data values for an item or items in a product specification data set upon a change or re-configuration of the data set. The context-specific data values advantageously enable the user-agent to dynamically “model” (shape or configure) various product specification data sets and evaluate the data sets as changes are made. [0007] More particularly, in various embodiments, described herein is a system that operates in a networked environment. It at least one aspect, the system comprises at least one server that includes a network interface, a non-transitory computer-readable medium having computer-executable instructions stored thereon, and a processor in communication with the network interface and the computer-readable medium. The processor is configured to execute the computer-executable instructions stored on the computer-readable medium. When executed, the computer-executable instructions implement components including at least a metric server adapter and a metrics application. [0008] In operation, the at least one server is configured to receive, via the network interface, at least one user-agent configured product specification data set. Each product specification data set identifies at least one item defined by a set of attributes having attribute data that includes two or more parameter values or a plurality of items having attributes that differ by at least one parameter value. [0009] In response to receipt of at least one product specification data set, the metrics application implements at least one evaluation service which causes the metrics application, for each product specification data set, to obtain time-dependent metric data from at least one data source accessible to the at least one server. The obtained metric data includes reference data for one or more responsive items having attributes that are responsive to attributes identified for a respective item in the product specification data set. Each responsive item in the metric data possesses a plurality of attributes that include at least one parameter value. [0010] The metrics application evaluates the plurality of attributes of each responsive item in the metric data relative to the set of attributes identified for the respective item in the product specification data set to dynamically discover relationships within the attribute data. Discovery of one or more relationships comprising a difference enables the metric server adapter to define one or more context-specific instructions for adapting the metric data for the respective item. [0011] The metrics application normalizes the metric data by executing the context-specific instructions for adapting the metric data for the respective item. Execution of at least one context-specific instruction causes one or more adjustment values to be applied to the reference data for one or more responsive items that differ by at least one parameter value from the respective item, transforming the reference data for the one or more responsive items, and automatically producing context-specific reference data for the respective item. [0012] The metrics application is further programmed to manage one or more user interfaces to expose one or a combination of the context-specific reference data values produced for the respective item or items as configured in the at least one product specification data set, via the network interface, to at least a client computing device associated with the user-agent that configured the at least one product specification data set. [0013] In another aspect, disclosed herein is a method that includes receiving, by at least one server, via a network interface, at least one user-agent configured product specification data set. The at least one server is operating under control of computer-executable instructions that, when executed by a processor, implement a plurality of components including at least a governing logic component and a production component. Each product specification data set identifies at least one item defined by a set of attributes having attribute data that includes two or more parameter values or a plurality of items that differ in accordance with at least one parameter value. [0014] For each received product specification data set, the method implements, by the production component, at least one evaluation service that, in operation, includes obtaining time-dependent metric data from at least one data source accessible to the at least one server. The obtained metric data includes reference data for one or more responsive items having attributes that are responsive to attributes identified for a respective item in the product specification data set. Each responsive item in the metric data possesses a plurality of attributes that include at least one parameter value. [0015] The method further includes evaluating, by the production component, the attribute data for each responsive item in the metric data in comparison to the set of attributes defined for the respective item in the product specification data set to dynamically discover relationships within the attribute data. Discovery of one or more relationships comprising a difference enables the governing logic component to define context-specific instructions for adapting the metric data for the respective item. [0016] The metric data is normalized by the production component which executes the context-specific instructions for adapting the metric data for the respective item. Execution of at least one context-specific instruction causes one or more adjustment values to be applied to the reference data for one or more responsive items that differ by at least one parameter value from the respective item, transforming the reference data for the one or more responsive items, and automatically producing context-specific reference data for the respective item. [0017] The method also includes managing, by the production component, one or more user interfaces to expose one or a combination of the context-specific reference data values produced for the respective item or items as identified in the at least one user-agent configured product specification data set, via the network interface, to at least a client computing device associated with the user-agent that configured the at least one product specification data set. [0018] In yet another aspect, disclosed herein is a non-transitory computer-readable medium having computer-executable instructions stored thereon for use in a networked environment including at least one server. The server operates under control of computer-executable instructions that, when executed by a processor, implement components including a governing logic component and a production component. When executed, the computer-executable instructions cause the server to perform operations that include receiving, via a network interface, at least one user-agent configured product specification data set. Each product specification data set identifies at least one item defined by a set of attributes having attribute data that includes two or more parameter values or a plurality of items that differ in accordance with at least one parameter value. [0019] The computer-executable instructions further cause the server to implement at least one evaluation service. For each received product specification data set, the computer-executable instructions cause the at least one server to obtain, by the production component, time-dependent metric data from at least one data source accessible to the at least one server. The obtained metric data includes reference data for one or more responsive items having attributes that are responsive to attributes identified for a respective item in the product specification data set. Each responsive item in the metric data possesses a plurality of attributes that include at least one parameter value. [0020] The production component evaluates the attribute data for each responsive item in the metric data relative to the set of attributes defined for the respective item in the product specification data set to dynamically discover relationships within the attribute data. Discovery of one or more relationships comprising a difference enables the governing logic component to define context-specific instructions for adapting the metric data for the identified item. [0021] The production component adapts the metric data for the respective item by executing at least one context-specific instruction that causes one or more adjustment values to be applied to the reference data for one or more responsive items that differ by at least one parameter value from the respective item. Application of the one or more adjustment values transforms the reference data for the one or more responsive items, and automatically produces one or more context-specific reference data values for the respective item. [0022] The production component exposes context-specific reference data values produced for the respective item or items as identified in the at least one user-agent configured product specification data set, via the network interface, to a client computing device associated with the user-agent that configured the at least one product specification data set. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS [0023] The foregoing aspects and many of the attendant advantages of the present disclosure will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: [0024] FIG. 1 is a block diagram of a prior art representative portion of the Internet; [0025] FIG. 2 is a pictorial diagram of a system of devices connected to the Internet, which depict the travel route of data; [0026] FIG. 3 is a block diagram of the several components of the buyer's computer shown in FIG. 2 that is used to request information on a particular route; [0027] FIG. 4 is a block diagram of the several components of an information server shown in FIG. 2 that is used to supply information on a particular route; [0028] FIG. 5 is a flow diagram illustrating the logic of a routine used by the information server to receive and process the buyer's actions; [0029] FIGS. 6A-6B are flow diagrams illustrating another embodiment of the logic used by the information server to receive and process the quotes and quote requests of both buyers and vendors; [0030] FIG. 7 is a flow diagram illustrating another embodiment of the logic used by the information server to execute the process of a catalog purchase; [0031] FIGS. 8A-8D are images of windows produced by a Web browser application installed on a client computer accessing a server illustrating one embodiment of the present disclosure; and [0032] FIG. 9 is a flow diagram illustrating one embodiment of the normalization process described herein. DETAILED DESCRIPTION [0033] The term “Internet” refers to the collection of networks and routers that use the Internet Protocol (IP) to communicate with one another. A representative section of the Internet 100 as known in the prior art is shown in FIG. 1 in which a plurality of local area networks (LANs) 120 and a wide area network (WAN) 110 are interconnected by routers 125 . The routers 125 are generally special-purpose computers used to interface one LAN or WAN to another. Communication links within the LANs may be twisted wire pair, or coaxial cable, while communication links between networks may utilize 56 Kbps analog telephone lines, or 1 Mbps digital T-1 lines, and/or 45 Mbps T-3 lines. Further, computers and other related electronic devices can be remotely connected to either the LANs 120 or the WAN 110 via a modem and temporary telephone link. Such computers and electronic devices 130 are shown in FIG. 1 as connected to one of the LANs 120 via dotted lines. It will be appreciated that the Internet comprises a vast number of such interconnected networks, computers, and routers and that only a small representative section of the Internet 100 is shown in FIG. 1 . [0034] The World Wide Web (WWW), on the other hand, is a vast collection of interconnected, electronically stored information located on servers connected throughout the Internet 100 . Many companies are now providing services and access to their content over the Internet 100 using the WWW. In accordance with the present disclosure, and as shown in FIG. 2 , there may be a plurality of buyers operating a plurality of client computing devices 235 . FIG. 2 generally shows a system 200 of computers and devices to which an information server 230 is connected and to which the buyers' computers 235 are also connected. Also connected to the Internet 100 is a plurality of computing devices 250 associated with a plurality of sellers. The system 200 also includes a communications program, referred to as CEA, which is used on the sellers' computing devices 250 to create a communication means between the sellers' backend office software and the server applications. [0035] The buyers of a market commodity may, through their computers 235 , request information about a plurality of items or order over the Internet 100 via a Web browser installed on the buyers' computers. Responsive to such requests, the information server 230 , also referred to as a server 230 , may combine the first buyer's information with information from other buyers on other computing devices 235 . The server 230 then transmits the combined buyer data to the respective computing devices 250 associated with the plurality of sellers. Details of this process are described in more detail below in association with FIGS. 5-7 . [0036] Those of ordinary skill in the art will appreciate that in other embodiments of the present disclosure, the capabilities of the server 230 and/or the client computing devices 235 and 250 may all be embodied in the other configurations. Consequently, it would be appreciated that in these embodiments, the server 230 could be located on any computing device associated with the buyers' or sellers' computing devices. Additionally, those of ordinary skill in the art will recognize that while only four buyer computing devices 235 , four seller computing devices 250 , and one server 230 are depicted in FIG. 2 , numerous configurations involving a vast number of buyer and seller computing devices and a plurality of servers 230 , equipped with the hardware and software components described below, may be connected to the Internet 100 . [0037] FIG. 3 depicts several of the key components of the buyer's client computing device 235 . As known in the art, client computing devices 235 are also referred to as “clients” or “devices,” and client computing devices 235 also include other devices such as palm computing devices, cellular telephones, or other like forms of electronics. A client computing device can also be the same computing device as the server 230 . An “agent” can be a person, server, or a client computing device 235 having software configured to assist the buyer in making purchasing decisions based on one or more buyer-determined parameters. Those of ordinary skill in the art will appreciate that the buyer's computer 235 in actual practice will include many more components than those shown in FIG. 3 . However, it is not necessary that all of these generally conventional components be shown in order to disclose an illustrative embodiment for practicing the present invention. As shown in FIG. 3 , the buyer's computer includes a network interface 315 for connecting to the Internet 100 . Those of ordinary skill in the art will appreciate that the network interface 315 includes the necessary circuitry for such a connection and is also constructed for use with TCP/IP protocol. [0038] The buyer's computer 235 also includes a processing unit 305 , a display 310 , and a memory 300 , all interconnected along with the network interface 315 via a bus 360 . The memory 300 generally comprises a random access memory (RAM), a read-only memory (ROM), and a permanent mass storage device, such as a disk drive. The memory 300 stores the program code necessary for requesting and/or depicting a desired route over the Internet 100 in accordance with the present disclosure. More specifically, the memory 300 stores a Web browser 330 , such as Netscape's NAVIGATOR® or Microsoft's INTERNET EXPLORER® browsers, used in accordance with the present disclosure for depicting a desired route over the Internet 100 . In addition, memory 300 also stores an operating system 320 and a communications application 325 . It will be appreciated that these software components may be stored on a computer-readable medium and loaded into memory 300 of the buyers' computer 235 using a drive mechanism associated with the computer-readable medium, such as a floppy, tape, or CD-ROM drive. [0039] As will be described in more detail below, the user interface which allows products to be ordered by the buyers are supplied by a remote server, i.e., the information server 230 located elsewhere on the Internet, as illustrated in FIG. 2 . FIG. 4 depicts several of the key components of the information server 230 . Those of ordinary skill in the art will appreciate that the information server 230 includes many more components than shown in FIG. 4 . However, it is not necessary that all of these generally conventional components be shown in order to disclose an illustrative embodiment for practicing the present invention. As shown in FIG. 4 , the information server 230 is connected to the Internet 100 via a network interface 410 . Those of ordinary skill in the art will appreciate that the network interface 410 includes the necessary circuitry for connecting the information server 230 to the Internet 100 , and is constructed for use with TCP/IP protocol. [0040] The information server 230 also includes a processing unit 415 , a display 440 , and a mass memory 450 , all interconnected along with the network interface 410 via a bus 460 . The mass memory 450 generally comprises a random access memory (RAM), read-only memory (ROM), and a permanent mass storage device, such as a hard disk drive, tape drive, optical drive, floppy disk drive, or combination thereof. The mass memory 450 stores the program code and data necessary for incident and route analysis as well as supplying the results of that analysis to consumers in accordance with the present disclosure. More specifically, the mass memory 450 stores a metrics application 425 formed in accordance with the present disclosure for managing the purchase forums of commodities products, and a metric server adapter 435 for managing metric data and the logic for adapting the metric data. In addition, the mass memory 450 stores a database 445 of buyer information continuously logged by the information server 230 for statistical market analysis. It will be appreciated by those of ordinary skill in the art that the database 445 of product and buyer information may also be stored on other servers or storage devices connected to either the information server 230 or the Internet 100 . Finally, the mass memory 450 stores Web server software 430 for handling requests for stored information received via the Internet 100 and the WWW, and an operating system 420 . It will be appreciated that the aforementioned software components may be stored on a computer-readable medium and loaded into the mass memory 450 of the information server 230 using a drive mechanism associated with the computer-readable medium, such as floppy, tape, or CD-ROM drive. In addition, the data stored in the mass memory 450 and other memory can be “exposed” to other computers or persons for purposes of communicating data. Thus, “exposing” data from a computing device could mean transmitting data to another device or person, transferring XML data packets, transferring data within the same computer, or other like forms of data communications. [0041] In accordance with one embodiment of the present disclosure, FIG. 5 is a flow chart illustrating the logic implemented for the creation of a Request for Quote (RFQ) by a singular buyer or a pool of buyers. In process of FIG. 5 , also referred to as the pooling process 500 , a buyer or a pool of buyers generate an RFQ which is displayed or transmitted to a plurality of sellers. Responsive to receiving the RFQ, the sellers then send quotes to the buyers. [0042] In summary, the creation of the RFQ consists of at least one buyer initially entering general user identification information to initiate the process. The buyer would then define a Line Item on a Web page displaying an RFQ form. The Line Item is defined per industry specification and units of product are grouped as a “tally” per industry practice. The pooling process 500 allows buyers to combine RFQ Line Items with other buyers with like needs. In one embodiment, the pool buy feature is created by a graphical user interface where the RFQ Line Items from a plurality of buyers are displayed on a Web page to one of the pool buyers, referred to as the pool administrator. The server 230 also provides a Web-based feature allowing the pool administrator to selectively add each RFQ Line Item to one combined RFQ. The combined RFQ is then sent to at least one vendor or seller. This feature provides a forum for pooling the orders of many buyers, which allows individual entities or divisions of larger companies to advantageously bid for larger orders, thus providing them with more bidding power and the possibility of gaining a lower price. [0043] The pooling process 500 begins in step 501 where a buyer initiates the process by providing buyer purchase data. In step 501 , the buyer accesses a Web page transmitted from the server 230 configured to receive the buyer purchase data, also referred to as the product specification data set or the Line Item data. One exemplary Web page for the logic of step 501 is depicted in FIG. 8A . As shown in FIG. 8A , the buyer enters the Line Item data specifications in the fields of the Web page. The Line Item data consists of lumber species and grade 803 , number of pieces per unit 804 , quantities of the various units comprising the preferred assortment in the tally 805 A-E, delivery method 806 , delivery date 807 , delivery location 808 , and the overall quantity 809 . In one embodiment, the buyer must define the delivery date as either contemporaneous “on-or-before” delivery date or specify a delivery date in the future for a “Forward Price” RFQ. In addition, the buyer selects a metric or multiple metrics in a field 810 per RFQ Line Item (tally). As described in more detail below, the metric provides pricing data that is used as a reference point for the buyer to compare the various quotes returned from the sellers. The buyer RFQ Line Item data is then stored in the memory of the server 230 . [0044] Returning to FIG. 5 , at a next step 503 , the server 230 determines if the buyer is going to participate in a pool buy. In the process of decision block 503 , the server 230 provides an option in a Web page that allows the buyer to post their Line Item data to a vendor or post their Line Item data to a buyer pool. The window illustrated in FIG. 8A is one exemplary Web page illustrating these options for a buyer. As shown in FIG. 8A , the links “Post Buyer Pool” 812 and “Post to Vendors” 814 are provided on the RFQ Web page. [0045] At step 503 , if the buyer does not elect to participate in a pool buy, the process continues to step 513 where the server 230 generates a request for a quote (RFQ) from the buyer's Line Item data. A detailed description of how the server 230 generates a request for a quote (RFQ) is summarized below and referred to as the purchase order process 600 A depicted in FIG. 6A . [0046] Alternatively, at decision block 503 , if the buyer elects to participate in a pool buy, the process continues to step 505 where the system notifies other buyers logged into the server 230 that an RFQ is available in a pool, allowing other buyers to add additional Line Items (tallies) to the RFQ. In this part of the process, the Line Items from each buyer are received by and stored in the server memory. The Line Items provided by each buyer in the pool are received by the server 230 using the same process as described above with reference to block 501 and the Web page of FIG. 8A . All of the Line Items stored on the server 230 are then displayed to a pool administrator via a Web page or an e-mail message. In one embodiment, the pool administrator is one of the buyers in a pool where the pool administrator has the capability to select all of the Line Item data to generate a combined RFQ. The server 230 provides the pool administrator with this capability by the use of any Web-based communicative device, such as e-mail or HTML forms. As part of the process, as shown in steps 507 and 509 , the pool may be left open for a predetermined period of time to allow additional buyers to add purchase data to the current RFQ. [0047] At decision block 509 , the server 230 determines if the pool administrator has closed the pool. The logic of this step 509 is executed when the server 230 receives the combined RFQ data from the pool administrator. The pool administrator can send the combined RFQ data to the server 230 via an HTML form or by other electronic messaging means such as e-mail or URL strings. Once the server 230 has determined that the pool is closed, the process continues to block 510 where the Line Items from each buyer (the combined RFQ) are sent to all of the buyers in the pool. The process then continues to step 513 where the server 230 sends the combined RFQ to the vendors or sellers. [0048] Referring now to FIG. 6A , one embodiment of the purchase-negotiation process 600 is disclosed. The purchase-negotiation process 600 is also referred to as a solicited offer process or the market purchase process. In summary, the purchase-negotiation process 600 allows at least one buyer to submit an RFQ and then view quotes from a plurality of vendors and purchase items from selected vendor(s). The logic of FIG. 6A provides buyers with a forum that automatically manages, collects, and normalizes the price of desired commodity items. The purchase-negotiation process 600 calculates a normalized price data set that is based on a predefined metric(s). The calculation of the normalized price data set in combination with the format of the Web pages described herein create an integrated forum where quotes for a plurality of inherently dissimilar products can be easily obtained and compared. [0049] The purchase-negotiation process 600 begins at step 601 where the RFQ, as generated by one buyer or a pool of buyers in the process depicted in FIG. 5 , is sent to a plurality of computing devices 250 associated with a plurality of sellers or vendors. The vendors receive the RFQ via a Web page transmitted by the server 230 . In one embodiment, the vendors receive an e-mail message having a hypertext link to the RFQ Web page to provide notice to the vendor. Responsive to the information in the buyers' RFQ, the process then continues to step 603 where at least one vendor sends their quote information to the server 230 . [0050] In the process of step 603 , the vendors respond to the RFQ by sending their price quote to the server 230 for display via a Web page to the buyer or buyer pool. Generally described, the vendors send an HTML form or an e-mail message with a price and description of the order. The description of the order in the quote message contains the same order information as the RFQ. [0051] FIG. 8B illustrates one exemplary Web page of a vendor quote that is displayed to the buyer. As shown in FIG. 8B , the vendor quote includes the vendor's price 813 , the lumber species and grade 803 , number of pieces per unit 804 , quantities of the various units comprising the preferred assortment in the tally 805 A-E, delivery method 806 , delivery date 807 , and delivery location 808 . In the quote response message, the vendor has the capability to modify any of the information that was submitted in the RFQ. For example, the vendor may edit the quantity values for the various units comprising the preferred assortment in the tally 805 A-E. This allows the vendor to adjust the buyer's request according to the vendor's inventory, best means of transportation, etc. All of the vendor's quote information is referred to as price data set or the RFQ Line Item (tally) quote. [0052] Returning to FIG. 6A , the process continues to step 605 , where the server 230 normalizes the price of each RFQ Line Item (tally) quote from each vendor. The normalization of the vendor's price is a computation that evaluates the vendor's price utilizing data from a metric. The normalization process is carried out because each vendor may respond to the Line Items of an RFQ by quoting products that are different from a buyer's RFQ and/or have a different tally configuration. The normalization of the metric pricing allows the buyers to objectively compare the relative value of the different products offered by the plurality of vendors. For example, one vendor may produce a quote for an RFQ of one unit of 2×4×10, two units of 2×4×12, and three units of 2×4×16. At the same time, another vendor may submit a quote for three units of 2×4×10, one unit of 2×4×12, and two units of 2×4×16. Even though there is some difference between these two offerings, the price normalization process provides a means for the buyer to effectively compare and evaluate the different quotes even though there are variations in the products. The price normalization process 900 is described in more detail below in conjunction with the flow diagram of FIG. 9 . [0053] Returning again to FIG. 6A , at step 607 the vendor's quote information is communicated to the buyer's computer for display. As shown in FIG. 8B and described in detail above, the vendor's quote is displayed via a Web page that communicates the vendor's quote price 813 and other purchase information. In addition, the vendor's quote page contains a metric price 815 and a quote price versus metric price ratio 816 . The metric price 815 and the quote price versus metric price ratio 816 are also referred to as a normalized price data value. A ratio higher than one (1) indicates a quote price that is above the metric price, and a lower ratio indicates a quote price that is below the metric price. [0054] Next, at step 609 , the buyer or the administrator of the buyer pool compares the various products and prices quoted by the vendors along with the normalized price for each Line Item on the RFQ. In this part of the process, the buyer may decide to purchase one of the products from a particular vendor and sends a notification to the selected vendor indicating the same. The buyer notifies the selected vendor by the use of an electronic means via the server 230 , such as an HTML form, a chat window, e-mail, etc. For example, the quote Web page depicted in FIG. 8B shows two different quotes with two different tallies, the first quote price 813 of $360, and the second quote price 813 A of $320. If the buyer determines that they prefer to purchase the materials listed in the first quote, the buyer selects the “Buy!” hyperlink 820 or 820 A associated with the desired tally. [0055] If the buyer is not satisfied with any of the listed vendor quotes, the server 230 allows the buyer to further negotiate with one or more of the vendors to obtain a new quote. This step is shown in decision block 611 , where the buyer makes the determination to either accept a quoted price or proceed to step 613 where they negotiate with the vendor to obtain another quote or present a counter-offer. Here, the server 230 provides a graphical user interface configured to allow the buyer and one vendor to electronically communicate, using, e.g., a chat window, streaming voice communications, or other standard methods of communication. There are many forms of electronic communications known in the art that can be used to allow the buyer and vendors to communicate. [0056] The buyer and seller negotiate various quotes and iterate through several steps 603 - 613 directed by the server 230 , where each quote is normalized, compared, and further negotiated until a quote is accepted by the buyer or negotiations cease. While the buyer and seller negotiate the various quotes, the server 230 stores each quote until the two parties agree on a price. At any step during the negotiation process, the system always presents the buyer with an option to terminate the negotiation if dissatisfied with the quote(s). [0057] At decision block 611 , when a buyer agrees on a quoted price, the process then continues to step 615 where the buyer sends a notification message to the vendor indicating they have accepted a quote. As described above with reference to steps 603 - 613 , the buyer notification message of step 615 may be in the form of a message on a chat window, e-mail, by an HTML form, or the like. However, the buyer notification must be transmitted in a format that allows the system to record the transaction. The buyer notification may include all of the information regarding the specifications by RFQ Line Item, such as, but not limited to, the buy price, date, and method of shipment, and payment terms. [0058] The purchase-negotiation process 600 is then finalized when the system, as shown in step 617 , sends a confirmation message to a tracking system. The confirmation message includes all of the information related to the agreed sales transaction. [0059] Optionally, the process includes step 619 , where the server 230 stores all of the information related to RFQ, offers, and the final sales transaction in a historical database. This would allow the server 230 to use all of the transaction information in an analysis process for providing an improved method of obtaining a lower market price in future transactions and in identifying optimum purchasing strategy. The analysis process is described in further detail below. Although the illustrated embodiment is configured to store the data related to the sales transactions, the system can also be configured to store all of the iterative quote information exchanged between the buyer and vendor. [0060] Referring now to FIG. 6B , an embodiment of the unsolicited offer process 650 is disclosed. In summary, the unsolicited offer process 650 , also referred to as the unsolicited market purchase process, allows at least one buyer to view unsolicited offers from a plurality of vendors and purchase items from a plurality of vendors from the offers. The logic of FIG. 6B provides buyers with a forum that automatically manages, collects, and normalizes price quotes based on metric data. By the price normalization method of FIG. 6B , the server 230 creates an integrated forum where offers for a plurality of inherently dissimilar products can be obtained and normalized for determination of a purchase. [0061] The unsolicited offer process 650 begins at step 651 where the plurality of vendors is able to submit offers to the server 230 . This part of the process is executed in a manner similar to step 603 of FIG. 6A , where the vendor submits a quote to the server 230 . However, in the Web page of step 651 , the server 230 generates a Web page containing several tallies from many different vendors. In addition, at step 651 , the server 230 stores all of the unsolicited offer data provided by the vendors. [0062] Next, at step 653 , a buyer views the offers stored on the server 230 . This part of the process is carried out in a manner similar to the process of step 603 or 607 where the server 230 displays a plurality of offers similar to the tallies depicted in FIG. 8A . [0063] Next, at step 655 , the buyer selects a metric for the calculation of the normalized price associated with the selected offer. As described in more detail below, metric data may come from publicly available information, i.e., price of futures contracts traded on the Chicago Mercantile Exchange, subscription services such as Crowes™ or Random Lengths™ processed via the metric server adapter 435 (shown in FIG. 4 ), or internally generated metrics derived from the data stored in the server 230 . The normalization calculation, otherwise referred to as the normalization process, occurs each time the buyer views a different offer, and the normalization calculation uses the most current metric data for each calculation. The normalization process is carried out because each vendor will most likely offer products that may vary from products of other vendors and have a different tally configuration from those supplied by other vendors. The normalization of the metric pricing allows the buyers to compare the relative value of the different products offered by the number of vendors. The metric price for each selected offer is displayed in a similar manner as the metric price 815 and 816 shown in the Web page of FIG. 8B . [0064] Next, at decision block 657 , the buyer selects at least one offer for purchase. This is similar to the process of FIG. 6A in that the buyer selects the “Buy!” hyperlink 820 associated with the desired tally to purchase an order. The process then continues to steps 659 - 663 , where, at step 659 , the process transmits a buy notice to the vendor, then, at step 661 , sends a purchase confirmation to the tracking system, and then, at step 663 , saves the transaction data in the server database. The steps 659 - 663 are carried out in the same manner as the steps 615 - 619 of FIG. 6A . In the above-described process, the buyer notification may include all of the information regarding the specifications by RFQ Line Item, and data such as, but not limited to, the buy price, date, and method of shipment, and the payment terms. [0065] Referring now to FIG. 7 , a flow diagram illustrating yet another embodiment of the present disclosure is shown. FIG. 7 illustrates the catalog purchase process 700 . This embodiment allows buyers to search for a catalog price of desired commerce items, enter their purchase data based on the pre-negotiated catalog prices, and to compare those catalog prices with a selected metric price and the current market price, wherein the current market price is determined by the purchase-negotiation process 600 . [0066] The process starts at step 701 where the buyer selects a program buy catalog 443 . The program buy catalog 443 provides buyers with the published or pre-negotiated price of the desired products. Next, at step 703 , based on the catalog information, the buyer then enters their purchase data. Similar to step 501 of FIG. 5 and the tally shown in FIG. 8A , the buyer sends purchase data to the server 230 , such as the desired quantity of each item and the lumber species, grade, etc. [0067] The process then proceeds to decision block 707 where the buyer makes a determination of whether to purchase the items using the catalog price or purchase the desired product in the open market. Here, the server 230 allows the user to make this determination by displaying the metric price of each catalog price. This format is similar to the metric price 815 and 816 displayed in FIG. 8B . [0068] At decision block 707 , if the buyer determines that the catalog price is better than a selected metric price, the process then proceeds to steps 709 , 711 , and 713 , where a program buy from the catalog is executed, and the buyer's purchase information is stored on the server 230 and sent to the vendor's system to confirm the sale. These steps 711 - 713 are carried out in the same manner as the confirmation and save steps 617 and 619 as shown in FIG. 6A . [0069] At decision block 707 , if the buyer determines that the metric price is better than the catalog price, the process continues to step 717 where the buyer's purchase data is entered into an RFQ. At this step, the process carries out the first five steps 601 - 609 of the method of FIG. 6A to provide buyers with the price data from the open market, as well as provide the normalized prices for each open market quote. At step 719 , the server 230 then displays a Web page that allows the user to select from a purchase option of a catalog or spot (market) purchase. At decision block 721 , based on the displayed information, the buyer will then have an opportunity to make a determination of whether they will proceed with a catalog purchase or an open market purchase. [0070] At decision block 721 , if the buyer proceeds with the catalog purchase, the process continues to step 709 where the catalog purchase is executed. Steps 709 - 713 used to carry out the catalog purchase are the same as if the buyer had selected the catalog purchase in step 707 . However, if at decision block 721 the buyer selects the option to proceed with the market purchase, the process continues to step 723 where the RFQ generated in step 717 is sent to the vendor. Here, the process carries out the steps of FIG. 6 to complete the open market purchase. More specifically, the process continues to step 609 where the buyer compares the normalized prices from each vendor. Once a vendor is selected, the negotiation process of steps 603 - 613 is carried out until the buyer decides to execute the purchase. Next, the transaction steps 615 - 619 are carried out to confirm the purchase, notify the tracking system, and save the transactional data on the historical database. [0071] Optionally, the process can include a step where the server 230 stores all of the information related to program buy and metric comparisons and the final sales transaction in a historical database. This would allow the server 230 to use all of the transaction information in an analysis process for providing an improved method of obtaining the value of the program. Although the illustrated embodiment is configured to store the data related to the sales transactions, the system can also be configured to store all of the iterative quote information exchanged between the buyer and vendor. [0072] The analysis process allows the server 230 to utilize the sales history records stored in steps 619 and 711 to generate price reports for communication to various third parties as well as provide a means of calculating current market prices for products sold in the above-described methods. The sales history records are also used as the source for a metric, such as those used in the process of FIGS. 6A, 6B, and 7 . As shown in steps 619 , 663 , and 711 , the server 230 continually updates the historical database for each sales transaction. The analysis reporting process allows a buyer or manager of buyers to conduct analysis on the historical information. This analysis would include multi-value cross compilation for purposes of determining purchasing strategies, buyer effectiveness, program performance, vendor performance, and measuring effectiveness of forward pricing as a risk management strategy. [0073] Referring now to FIG. 9 , a flow diagram illustrating the logic of the normalization process 900 is shown. The logic of the normalization process 900 resides on the server 230 and processes the quotes received from commodity sellers. The logic begins at step 905 where quote data is obtained from the seller in response to the buyer's RFQ as described above. [0074] Next, at step 910 , routine 900 iteratively calculates the board footage (BF) of each type of lumber. Once all the totals are calculated for each type, routine 900 continues to step 915 where the server 230 calculates the total type price. [0075] At step 915 , routine 900 iteratively calculates the total type price for the amount of each type of lumber specified in the quote. This is accomplished by taking the total board footage (BF) calculated in block 910 and multiplying the total BF by the price per MBF specified in the quote. Once all the prices are calculated for each type, routine 900 continues to step 920 where the server 230 calculates the total quoted price. At step 920 , the routine 900 calculates the total price for the quote by summing all of the total type prices calculated at step 915 . [0076] At step 925 , the routine 900 iteratively retrieves the most current price for each type of lumber specified in the quote from a predefined metric source(s). Metric data may come from publicly available information, i.e., price of futures contracts traded on the Chicago Mercantile Exchange, subscription service publications such as Crowes™ or Random Lengths™ processed via the metric server adapter 435 (shown in FIG. 4 ), or internally generated metrics derived from the server database. Once all the prices are retrieved for each type, at step 930 , the routine 900 then iteratively calculates the market price for the quantity of each type of lumber in the quote. Once the totals for all types are calculated, the routine 900 continues to step 935 where the routine 900 calculates the total market price for the quote by summing all the most current prices calculated in step 930 . Although this example illustrates that steps 910 - 920 are executed before steps 925 - 935 , these two groups of steps can be executed in any order, or in parallel, so long as they are both executed before a comparison step 940 . [0077] At step 940 , routine 900 compares the total quoted to the metric price to arrive at a comparative value. In one exemplary embodiment of the current invention, the comparative value is a “percent of metric” value. A value higher than one hundred (100) percent indicates a price that is above the metric rate, and a lower percent indicates a price that is below the metric rate. [0078] The operation of routine 900 can be further illustrated through an example utilizing specific exemplary data. In the example, a buyer sends out a request for a quote (RFQ) requesting a lot of 2×4 S&B lumber consisting of five units of 2″×4″×8′, two units of 2″×4″×14′, and five units of 2″×4″×16′. The buyer then receives quotes from three sellers. Seller A responds with a tally of six units of 2″×4″×8′, four units of 2″×4″×14′, and three units of 2″×4″×16′ for $287 per thousand board feet. Seller B responds with a lot of five units of 2″×4″×8′, one unit of 2″×4″×14′, and six units of 2″×4″×16′ for $283 per thousand board feet. Seller C responds with a lot of one unit of 2″×4″×8′, five units of 2″×4″×14′, and five units of 2″×4″×16′ for $282 per thousand board feet. Suppose also that the typical unit size is 294 pieces/unit, and the metric or reported market price for 2″×4″×8's is $287.50, for 2″×4″×14's is $278.50, and for 2″×4″×16′ is $288. [0079] Viewing the MBF prices for the respective quotes is not particularly informative, given that certain lengths of lumber are more desirable and priced accordingly in the marketplace. By processing the quote from Seller A using routine 900 , we arrive at a total MBF of 29.792, giving a total quoted price of $8,550.30. The selected metric price for the same types and quantities of lumber would be $8,471.12; therefore, the quoted price would have a percent of market value of 100.93%. Processing the quote from Seller B using routine 900 , we arrive at a total MBF of 29.400, giving a total quoted price of $8,320.20. The selected metric price for the same types and quantities of lumber, however, would be $8,437.21; therefore, the quoted price would have a percent of market value of 98.61%. Finally, processing the quote from Seller C using routine 900 , we arrive at a total MBF of 30.968, giving a total quoted price of $8,732.98. The selected metric price for the same types and quantities of lumber, however, would be $8,767.66; therefore, the quoted price would have a percent of market value of 99.38%. By looking at the percent of selected metric value, it is apparent that the price from Seller B is a better value. As shown in the methods of FIGS. 5-7 , this price normalization process allows users to compare inherently different offers having different quality and quantity values. [0080] In yet another example of an application of the normalization process, additional exemplary data is used to demonstrate the analysis of a transaction having one RFQ from a buyer and two different quotes from a seller, normalized to comparable product of another species. In this example, the buyer produces an RFQ listing the following items: one carload of Eastern SPF (ESPF) lumber having four units of 2″×4″×8′, four units of 2″×4″×10′, six units of 2″×4″×12′, two units of 2″×4″×14′, and six units of 2″×4″×16′. The vendor then responds with two different quotes with two different unit tallies and two different prices. The first response lists a quote price of $320 per thousand board feet, and a slight modification of the tally provides four units of 2″×4″×8′, four units of 2″×4″×10′, six units of 2″×4″×12′, three units of 2″×4″×14′, and five units of 2″×4″×16′. The second response quotes per the requested tally at a price of $322 per thousand board feet. Both quotes list the delivery location as “Chicago.” [0081] To display the quotes, the server 230 produces a Web page similar to that displayed in FIG. 8C , where the vendor's modified tally is displayed in highlighted text. The buyer can then view a summary metric comparison or select the hypertext link “View Calculation Detail,” which then invokes the server 230 to produce a Web page as shown in FIG. 8D . Referring now to the Web page illustrated in FIG. 8D , the data produced by the server 230 compares the response to a selected metric of a different species, Western SPF (WSPF), for items of the same size, grade, and tally. The market price for the same 2×4 tally of ESPF and WSPF are thus simultaneously compared. In an example, Eastern quoted at $322 per thousand board feet, Western metric (Random Lengths™ 6/26/2000 print price plus freight of $80/M as defined in Metric Manager) for the same tally being $331.791. This metric comparison is also represented as Quote/Metric Value or Eastern price representing 0.970490, or 97% of comparable Western product. [0082] In review of the normalization process, the buyer must select a metric source for price information for a defined item given a set of attributes, i.e., grade, species, and size. The metric may then be mapped to the RFQ item for comparison and does not have to be the equivalent of the item. For instance, as explained in the above-described example, it may be desirable to map the market relationship of one commodity item to another. The most current pricing data for the metric is electronically moved from the selected source to the server 230 . As mentioned above, metric data may come from publicly available information, (i.e., price of futures contracts traded on the Chicago Mercantile Exchange), or subscription services, (i.e., Crowes™ or Random Lengths™ publications), or be an internal metric generated by the server 230 . This metric data is used in the normalization process for all calculations, as described with reference to the above-described methods. [0083] While various embodiments of the invention have been illustrated and described, it will be appreciated that within the scope of the appended claims, various changes can be made therein without departing from the spirit of the invention. For example, in an agricultural commodity, an order for Wheat U.S. #2 HRW could be compared to a selected metric of Wheat U.S. #2 Soft White, similar to how different species are analyzed in the above-described example. [0084] The above system and method can be used to purchase other commodity items, such as in the trade of livestock. In such a variation, order information such as a lumber tally would be substituted for a meat type, grade, and cut. Other examples of commodity items include agricultural products, metals, or any other items of commerce having several order parameters.

A system includes a server that implements a metric server adapter and a metrics application. The server receives a user-agent configured product specification data set that identifies an item or items having attributes which causes the metrics application to obtain time-dependent metric data. The metric data includes reference data for one or more responsive items responsive to a respective item in the product specification data set. The metrics application dynamically discovers differences in the attribute data, which enables the metric server adapter to define context-specific instructions for adapting the metric data for the respective item. An adjustment value applied to the reference data transforms the reference data and produces context-specific reference data for the respective item. One or more user interfaces expose the context-specific reference data values produced for the user-agent configured product specification data set to at least a client computing device associated with the user-agent.

This is a continuation of application Ser. No. 07/996,734 filed on Dec. 24, 1992, now U.S. Pat. No. 5,317,502, which is a continuation of application Ser. No. 07/746,285 filed on Aug. 13, 1991, now U.S. Pat. No. 5,251,123, which is a continuation of application Ser. No. 07/616,732 filed on Nov. 21, 1990, abandoned, which is a continuation of application Ser. No. 07/363,287 filed on Jun. 7, 1989, abandoned, which is a continuation of application Ser. No. 07/110,140 filed on Oct. 19, 1987, abandoned. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved high resolution system for electrically sensing the spatial coordinates of a electronic point specifying device such as a stylus ("stylus" is used herein to describe the hand-held probe or other point specifying device) with respect to a conductive two-dimensional coordinate system independent of variations of the stylus in the third orthogonal dimension. Using a high precision input signal, precision signal processing, and by removing stochastic and deterministic noise, the preset invention improves point sensing precision and accuracy and hence the precision and accuracy of the spatial coordinates calculation. 2. Description of Prior Art The present invention is an improvement over the prior art as disclosed in U.S. Pat. No. 4,603,231 (the "'231 Patent"), issued to L. Reiffel, et al., for "System for Sensing Spatial Coordinates", which is hereby incorporated by reference. The present invention will be described by way of reference to its distinguishments from the '231 Patent. The present invention provides significant improvements in precision over the prior art as described in the '231 Patent. Substantial improvements in the precision of the sensed coordinates is achieved by substantial removal of stochastic noise signals from the information signal. By removing noise from the information signal, the precision of the present invention is improved over the prior art. In sensing the position of a coordinate, the prior art system collected information by processing the output of a full-wave rectifier with a low-pass "time-averaging" filter. The low-pass filter weighted the input signal with respect to time such that the most recent signal input had greater weight than the previous signal. The weight of the signal at each instant in time during the sampling period has unacceptably large variance. Although this system was highly precise with respect to its constituent components and the display devices available at the time of its conception, the prior art system cannot provide the precision available with current components and display devices such as high resolution monitors. The present invention implements a precision integrating system that integrates equally weighted periods of time and averages these periods of time such that all input information has equal weight. The final value of the integration is not dependant on the sequence of input events, only the magnitude and quantity of the events. In contrast with the time averaging or low-pass filtering system of the prior art, in which later events weigh more heavily than earlier events, the integrator of the present invention provides improved performance over the low-pass "time-averaging" filter method since the weight of each sample is proportionate to the sample interval. The present invention's signal processing method maintains the integrity of the input signal and reduces noise, thereby improving the precision of the coordinate sensing. Additionally, the hand held stylus used in prior art systems as an input device was inadequate for the high resolution capabilities of the present invention. Therefore, the stylus, a functionally dependent component of the present invention, provides precision sensing of coordinate location equal to the overall electronic performance of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram illustrating the major system blocks of the present invention. FIG. 2 is a detailed block diagram illustrating the preferred embodiment of the present invention. FIG. 2A is a schematic of the stylus signal sensing circuitry. FIG. 3 is a cross section of the stylus input device of one embodiment of the present invention. FIGS. 4A and 4B are detailed diagrams of the zero travel switch of one embodiment of the present invention. FIG. 5 is a diagram illustrating the major component layers in the construction of one embodiment of the conductive surface of the present invention. FIG. 6 is a cross section of the laminae used in the construction of one embodiment of the conductive surface of the present invention. FIGS. 7 and 7A illustrate one embodiment of the connection of a printed circuit board to the conductive layer of the composite lamination via a conductive rivet. FIG. 8 illustrates the positioning of the component printed circuit boards around the perimeter of a transparent laminated conductive surface in one embodiment of the present invention. FIG. 9 illustrates the timing relationships of one cycle for driving the four edges of the conductive surface in the preferred embodiment. FIG. 10 is an enlargement of a particular interval of the timing diagram of FIG. 9 for illustrating the significance of timing relationships on the precision of the present invention. FIG. 11 is a horizontal and vertical enlargement of a particular interval of the timing diagram of FIG. 10 for illustrating the significance of timing relationships on the precision of the present invention. FIG. 12 is a schematic of the edge driver PCB boards. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 provides an overview of the preferred embodiment of the present invention. The major functional blocks, all as described in the '231 Patent (the terminology used herein sometimes differs from the exact terminology used in the '231 Patent), are depicted in FIG. 1 as follows; drive signal generator (DSG) 10, conductive surface 6, stylus 2, analog signal processor (ASP) 28, variable timing generator (VTG) 14 and central processing unit (CPU) 20. The VTG consists of sequential logic which is well known in the art as in Mano, M. Morris, Digital Logic and Computer Design, (1979), which is hereby incorporated by reference. DSG 10 produces a highly precise and consistent system drive signal 8. Drive signal 8 is alternately applied to each of the four sides of conductive surface 6. DSG 10, with timing control signals from VTG 14, alternately drives each of the four sides of conductive surface (overlay) 6 via drive signal 8. As an example of the parameters of such drive signals useful in the present invention, in the preferred embodiment drive signal 8 is an eight (8) volts peak to peak (vpp), positive six (6) volt offset, 250 kHz sine wave. As depicted in FIG. 1, stylus 2 senses a capacitively coupled signal (denoted as capacitive coupling 4 in FIG. 1) from conductive surface 6 as drive signal 8 is applied to each of the four sides of conductive surface 6. Stylus 2 amplifies the detected capacitively coupled signals 4 (one for each side of conductive surface 6 driven by drive signal 8), and transmits stylus output signal 30 to ASP 28. Stylus 2 also contains a switch (not explicitly shown in FIG. 1) which indicates the status of stylus 2, either "pen up" (not touching conductive surface 6) or "pen down" (touching conductive surface 6). The switch is used to turn off stylus 2 when stylus 2 is not in use. Without this switch, stylus 2 is capable of sensing coordinates with respect to conductive surface 6 without contact with conductive surface 6 and in the third orthogonal dimension, as described in the '231 Patent. Within ASP 28, a digital gain control (DGC) (not explicitly shown in FIG. 1) sets the gain for stylus output signal 30. The signal gain can be adjusted to allow for full utilization of the entire range of an analog to digital converter (ADC) (internal to ASP 28 and not explicitly shown in FIG. 1) independent of the amplitude of coupled signal 4 detected by stylus 2. ASP 28 also includes a band-pass filter, precision rectifier, and an integrator (see FIG. 2) which, in combination, condition stylus output signal 30 for processing by the ADC internal to ASP 28. Each of the major blocks presented in FIG. 1 will be developed in further detail throughout the detailed description of the preferred embodiment. FIG. 9 illustrates the timing relationships used in the preferred embodiment for one cycle of driving the four edges of conductive surface 6. Signal 142 (comprising two discrete digital signals 142A and 142B) provides a two (2) bit encoded signal which identifies which edge of conductive surface 6 will be driven during time periods 202-204, 204-206, 206-208 and 208-210. Non-rectangular alternative embodiments of the present invention use the same principal as that of rectangular conductive surface 6. Signal 142, however, may require more than two (2) bits for the drive direction coding for conductive surfaces shapes with more than four (4) sides. Starting at point 202, the two (2) bit encoded signal produced by signal 142 A,B is 0,0, which, for this example, indicates that the edge controlled by signal 116A is grounded and the edge opposite to the edge controlled by signal 116A is driven by drive signal 8 during time interval 202-204. Similarly, beginning at point 204, the two (2) bit encoded signal 142 A,B is 1,0, and the edge controlled by signal 116B is grounded and the edge opposite to the edge controlled by signal 116B is driven by drive signal 8 during time interval 204-206; beginning at point 206, the two (2) bit encoded signal 142 A,B is 0,1, and the edge controlled by signal 116C is grounded and the edge opposite to the edge controlled by signal 116C is driven by drive signal 8 during time interval 206-208; and beginning at point 208, the two (2) bit encoded signal 142 A,B is 1,1, and the edge controlled by signal 116D is grounded and the edge opposite to the edge controlled by signal 116D is driven by drive signal 8 during time interval 208-210. As is apparent from FIG. 9, encoded signal 142A,B identifies the edge of conductive surface 6 to be grounded and the edge of conductive surface 6 to be driven by drive signal 8 during a specified time interval, and thus provides a logical means to timely apply drive and ground signals for all four (4) drive directions of conductive surface 6. Also shown in FIG. 9 are the signals which control particular components of the preferred embodiment of the present invention (see FIG. 2): analog to digital converter control signal 168, integrator control signal 160, integrator reset control signal 156, rectifier control signal 136, and the relationship of these signals with respect to edge drive control signals 116 A-D and two (2) bit encoded drive direction signal 142 A,B. FIG. 10 provides an enlargement of interval 212-204 in FIG. 9 to more fully illustrate the relationships among various digital and analog signals and the effect of these relationships on the precision of the present invention. Interval 215-203 of integrator output signal 155 shows the substantially exponential decay of integrator output signal 155 during a beginning portion of drive cycle interval 202-204 (see FIG. 9). In the preferred embodiment, interval 203-218 of integrator output signal 155 illustrates integrator input signal 158 being sampled for ten (10) periods. The section of integrator output signal 155 from 203 to 218 represents the integral, multiplied by a constant, of integrated input signal 158. It should be noted that switching the integrator on and off, at points 203 and 218, respectively, of FIG. 10 occurs at a point in time when half wave rectified system input signal 158 is at zero. Switching at zero periods prevents the addition of the signal distorting switching spikes and phase jitter error to the drive signal. FIG. 11 provides a horizontal and vertical enlargement of a time interval near timing event 200 of FIG. 10 to more fully illustrate the timing relationships and the effect of these relationships on the precision of the present invention. Of particular significance in FIG. 11 is near timing event 200 involving integrator control signal 160, integrator reset switch control signal 156 and output rectifier switch control signal 136. At time 216 integrator 102 (see FIG. 2) is turned off by integrator control signal 160 and at time 203 integrator 102 is turned on by integrator control signal 160. At time 220, subsequent to integrator 102 turn off at time 216, integrator reset switch 100 is turned off by integrator reset switch control signal 156. At time 222 rectifier output switch 46 is turned on by output rectifier switch 136. Up until time 222 of FIG. 11, rectifier output switch 46 is turned off, and no analog input signal (ultimately originating at stylus 2 of FIG. 1) is passed to integrator 102. When signals 160 and 156 are simultaneously low, both integrator 102 and integrator reset switch 100 are turned on. During the time when integrator 102 and integrator reset switch 100 are both turned on and when rectifier output switch 136 is switched off, the charge built up on the capacitor internal to integrator 102 (the capacitor is not explicitly shown in FIG. 2) decays exponentially through path 154 of FIG. 2, as shown in FIG. 10 interval 215-203, to an insignificant level. Since rectifier output switch 46 is not permitting input signal 158 to be integrated during the time when integrator 102 and integrator reset switch 100 are both on, any residual charge is dissipated from the capacitor internal to integrator 102 through path 154 of FIG. 2. The dissipation of the charge on the capacitor prevents any residual charge from offsetting the next integration of input signal 158 to integrator 102. While the capacitor internal to integrator 102 never discharges completely to zero, the charge on this capacitor is allowed to decay exponentially such that the total value of the integration cycle is not distorted by residual charge from the previous integration. In the preferred embodiment of the present invention, the charge is allowed to decay for approximately 14 microseconds, resulting in residual charge within one least significant bit of the reset voltage. FIG. 2 provides a detailed block diagram of the improved system for sensing spatial coordinates of the present invention. Sine wave generator 36 generates a stable-amplitude sine wave output 126 and a corresponding square wave output 118. In the preferred embodiment of the present invention sine wave generator 36 is an Intersil ICL8038 Precision Waveform Generator/Voltage Controlled Oscillator. Use and application of such a wave generator is known in the art and is described in Intersil Hot Ideas in CMOS Data Book, (1983/1984), which is hereby incorporated by reference. Sine wave output 126 is used as the system driving signal and square wave output 118 is used to phase lock sine wave generator 36 to state machine 114. Sine wave output 126 and square output 118 have a substantially fixed phase relationship as established by sine wave generator 36. Phase comparator 48 of the preferred embodiment, to which square wave output 118 is input, is a National Semiconductor MM74HC4046 CMOS Phase Lock Loop. Use and application of such a phase lock loop is known in the art and is described in National Semiconductor Logic Data Book Volume 1, which is hereby incorporated by reference. The consistency of the amplitude of sine wave output 126 provides a highly stable and therefore highly predictable system driving waveform for the present invention. The predictability of the driving waveform minimizes one area of errors, which increases the reliability of the processed information and subsequently increases the overall precision of the present invention. Phase comparator 48 is used to phase lock the independent, free-running sine wave output 126 from sine wave generator 36 to the oscillator (not explicitly shown) in state machine 114 thereby maintaining a constant phase angle between sine wave output 126 and the oscillator in state machine 114. As is known in the art, maintaining a constant phase angle by phase locking prevents out of phase signals from drifting or "creeping" in phase or frequency. It is difficult to filter out low frequency noise created by changing phase between signals, and phase locking with phase comparator 48 eliminates the need to filter out low beat frequencies between the two independent oscillators (sine wave generator 36 and the oscillator in state machine 114). Phase comparator 48 causes sine wave generator 36 to oscillate at substantially the same frequency as the incoming carrier frequency that is generated by the oscillator in state machine 114, which in the preferred embodiment is 250,000 Hz. A major advantage of the use of phase comparator 48 is that, since the clock driving CPU 110 is derived from the clock internal to state machine (this clock is not explicitly shown in FIG. 2), any noise generated by CPU 110 is synchronized with sine wave generator 36, thereby increasing the precision of the present invention. As described above, phase comparator 48 phase locks sine wave generator 36 and the oscillator internal to state machine 114. Any digital noise generated or picked up by sine wave generator 36, ASP 28 or associated circuits is synchronous with respect to the start and stop periods for integrator 102, which is driven by a clock derived from the oscillator internal to state machine 114, as noted in the discussion of FIG. 9 and FIG. 10 above. The synchronization of noise to these clocks results in the elimination of phase shifts of "digital noise" with respect to analog signal 30, which reduces system noise when using the "Reference Shift Technique" described in the '231 Patent. Phase lock loop techniques utilized in the preferred embodiment contribute to increased precision of the present invention. Sine wave output 126 is amplified by power amplifier 34. An example of a component suitable for use in the present invention is the National Semiconductor LM318 Operational Amplifier. The use of such a component as an LM318 Operational Amplifier in combination with output transistors and passive components to implement a power amplifier such as power amplifier 34 is known in the art and is described in such publications as the National Semiconductor Linear Data Book, which is hereby incorporated by reference. The output of power amplifier 34 is used to drive the conductive surface 6 through overlay edge PCBs 32, further described below. As is known in the art, a sinusoidal waveform is characterized by its peak value V P , its frequency w and its phase with respect to an arbitrary reference time. Since sine wave output 126 from sine wave generator 36 is generated with high consistency and precision, overlay drive signal 122 output from power amplifier 34 is more consistent and precise and provides a substantial improvement in performance of the present invention over prior art systems. In the preferred embodiment, edge driver printed circuit boards (PCBs) 32 around the perimeter of conductive surface 6 are such that multiple identical PCBs apply respective drive signals to the edges of conductive surface 6. In another embodiment, the edge driver circuitry (PCBs 32) is embodied in a single, contiguous PCB 32 with its center cut out, wherein the center cut-out is in the shape of conductive surface 6 and permits connection of conductive surface 6 to edge driver PCB 32. Edge driver PCBs 32 apply drive signals from power amplifier 34 to the respective edges of conductive surface 6 (see FIGS. 8 and 12). Driving of the edges of conductive surface 6 is performed by drive buffers included on edge driver PCBs 32 (not explicitly shown), which provides alternating current to alternating opposite edges of conductive surface 6 as determined by control signals generated by variable timing generator (VTG) 14 (see signals 116A-D and 142 A,B of FIG. 9). VTG 14 sends control signal 12 (see FIG. 1) to the drive buffers on edge driver PCBs 32, thereby causing the drive buffers to supply current to each pair of opposite edges of conductive surface 6 in turn. Through appropriate control signals generated by VTG 14, drive signal current is alternately supplied to the pair of opposing edges perpendicular to a defined "X axis" for a relatively short predetermined period of time, and then supplied to the opposing edges perpendicular to a defined "Y axis" for another relatively short predetermined period of time (the X axis and the Y axis are substantially perpendicular in the preferred embodiment). Thus at any moment, an alternating current sheet will be flowing between one pair of opposing edges, and later such current will flow between the other pair of opposing edges. The voltage induced by this alternating current flow, which is sensed by stylus 2, is therefore a variable in both time and position, depending upon which pair of edges are being supplied current and upon the position of stylus 2 relative to conductive surface 6. Although many types of drives may be used, FIG. 12 shows a schematic of the preferred embodiment of the present invention, which utilizes bipolar junction transistors to provide the required current across the conductive surface. These drive transistors are mounted on overlay edge PCB 32 directly above the points they drive. The bipolar junction transistors 300 provide a more precise method of ensuring that the entire reference edge is at ground. Conductive surface 6 of the preferred embodiment is constructed as shown in FIG. 5, FIG. 6 and FIG. 7. Illustrated in FIG. 5 are the three primary laminate components: conductive film 172, adhesive film 174 and plexiglass layer 176, respectively. In the preferred embodiment of the present invention each layer is a continuous surface of material. Adhesive film 174 bonds conductive film 172 to plexiglass layer 176. In the preferred embodiment, plexiglass layer 176 protects and supports the layers comprising conductive surface 6, while also providing a surface on which to print illustrative graphics, such as representations of controls for conductive surface 6 as is described in U.S. patent application Ser. No. 914,924 filed Oct. 3, 1986 by Jakobs, et al, for "Integrated Multi-Display Overlay-Controlled Workstation," which is hereby incorporated by reference. The graphics are printed on plexiglass layer 176 on the surface between adhesive layer 186 (see FIG. 6) and plexiglass layer 176 so that if a user contacts conductive surface 6 with stylus 2, the graphics are protected from abrasive wear by contact with stylus 2. It is apparent to one skilled in the art that alternative materials can be utilized for the protective and supportive surface material other than plexiglass as in plexiglass layer 176. Opaque materials may be used as well as transparent materials, with or without graphics printed on the material. An alternative surface may be of a patterned or randomly textured material. FIG. 6 illustrates in greater detail the various layers of material which comprise conductive surface 6 in the preferred embodiment of the present invention. Of the three primary layers from FIG. 5 172, 174 and 176, conductive film 172 and adhesive film 174 are comprised of sub-layers. Conductive film 172 has conductive material 180 deposited or otherwise coated on mylar film 178. In other embodiments other suitable film substrates are substituted for mylar film 178. Adhesive film 174 consists of film substrate 184, on both sides of which is coated with adhesive layers 182 and 186 which serve to bond conductive film 172 to plexiglass layer 176. The preferred embodiment of the present invention uses a continuous layer of electrically conductive indium tin oxide (ITO) of uniform resistivity for conductive material 180, which is deposited on mylar film 178. Although ITO has been specified as conductive material 180 comprising the conductive layer of conductive surface 6, alternative suitable conductive materials are used in other embodiments. The conductive layer can be of continuous or semi-continuous electrically conductive material. In the preferred embodiment it is advantageous for conductive surface 6 to be transparent as it can then be placed in front of visual display devices such as CRTS, liquid crystal displays or video projection devices, wherein these display devices produce the electrical representation of the corresponding spatial coordinates on a graphic display. Among the alternative optically transparent, conductive materials suitable for use as conductive material 180 to be coated or otherwise deposited on mylar film are: stannous oxide, indium oxide, or thin metal films deposited on a transparent substrate of quartz, glass, or optical grade acetate. In an alternative embodiment, wire meshes or etched sheets are used in situations demanding extreme ruggedness, large areas, or non-rectilinear surfaces. The drive direction of the current in conductive surface 6 is controlled by control signal driver 112 (see FIG. 2). Control signal driver 112 receives four (4) bits of decoded directional information 144 from state machine 114 and also receives control signal 148 from microprocessor ports 108. Inputs 144 and 148 to control signal driver 112 provide the necessary information to control the drive directions of conductive surface 6 via conductive surface edge PCBs 32. Control signal driver 112 provides eight (8) edge PCB 32 control signals 116 per pair of coordinates sensed, two (2) control signals 116 for each drive direction. As illustrated in FIGS. 7 and 7A, in the preferred embodiment PCBs 32 are connected to the drive points of conductive surface 6 via wire 190. A plurality of such wires as wire 190 are connected along the perimeter of conductive surface 6 at predetermined substantially equidistant intervals. As an example of the connection at each drive point along the perimeter of conductive surface 6, FIG. 7 and 7A will be further described. Wire 190 is fixed to conductive rivet 202 with flexible conductive material 200. The electrical connection between rivet 202 and conductive material 180 is enhanced by a ring of conductive ink 204 placed on top of conductive material 180. By securing rivet 202 to both sides of conductive film 172, and thereby creating a conductive bridge, the protection afforded by mylar film 178 over the conductive material 180 is retained without a decrease in conductivity. Further, the use of flexible conductive material 200 to secure wire 190 to rivet 202 reduces the stresses exerted on the joint between wire 190 and rivet 202, which reduces the possibility for failure of this joint, thereby enhancing mechanical reliability. With reference to FIG. 2 and FIG. 2A, conductive surface 6 as detailed above is electrostatically coupled (denoted as coupling 4) to stylus tip 50. Conductive surface 6 is capacitively coupled to an inverting op amp 304 internal to stylus 2 via what is known in the art, see Tobey, Graeme, Huelsman, Burr-Brown Operational Amplifiers Design and Applications, (1971), as a current input to op amp 304 that is at virtual ground. The current input at virtual ground results in no voltage swing across the parasitic capacitance 302. Since the current input of stylus 2 has low impedance, the voltage induced on it is small and the resulting parasitic current to the antenna shield 56 of stylus 2 is small, resulting in small loss of coupled signal 4 to stylus 2 thus maximizing the available energy to op amp 304. While voltage sensing could be used as the input signal to stylus 2, the voltage induced on the signal 30 would be high and the resulting parasitic current through parasitic capacitance 302 to the antenna shield would also be high, resulting in detrimental effects to the signal. In a preferred embodiment of the present invention, stylus 2 is constructed as shown in FIG. 3. The preferred embodiment of stylus tip 50 consists of an electrically conductive composite material. A tip constructed of conductive material essentially locates the signal sensing tip of stylus 2 at the signal transmission source on conductive surface 6. For the preferred embodiment of stylus tip 50, teflon is used as a friction reducing matrix material in which the preferred conductive material within the matrix is carbon. Carbon serves as an efficient conductive material for stylus tip 50. Brass sleeve 52 provides a rigid structure to support non-rigid stylus tip material 50. Sleeve 52 is wrapped with an insulating material 54 so that brass sleeve 52 does not contact electromagnetic shield 56. Stylus tip 50 is shielded from electromagnetic noise sources such as fingers by electromagnetic shield 56. In the preferred embodiment, stylus 2 also includes plastic grip 62 as shown in FIG. 3. Plastic grip 62 is contoured to optimize the comfort of the user's grip on stylus 2 and the position of the user's hand relative to stylus tip 50. The user's hand must grip stylus 2 close enough to stylus tip 50 in order to control stylus 2 in a comfortable and intuitive fashion. However, if the user's fingers are too close to stylus tip 50, stylus 2 will sense the user instead of conductive surface 6, resulting in distortion of the actual location of stylus 2 relative to conductive surface 6. Additionally, locating the grip with the user's fingers positioned too close to stylus tip 50 will make stylus 2 feel unbalanced, difficult to control and tiring to use. The concave design of plastic grip 62 serves two purposes. First, the concave design forces the user to grip stylus 2 in the optimum position which keeps the user's fingers away from stylus tip 50 while providing a comfortable balance of stylus 2. Second, the concave design maintains a comfortable diameter for gripping stylus 2 while the diameter of stylus body 64 can be increased to increase the amount of circuitry which can be contained in stylus body 64. Within stylus body 64, electromagnetic shield 56 contains stylus tip 50, brass sleeve 52 houses stylus tip 50 and insulation 54 covers brass sleeve 52. Electromagnetic shield 56 acts to shield the antenna created by stylus tip 50 and brass sleeve 52 from fingers and other sources of electromagnetic radiation which could induce noise into the input signal path. Electromagnetic shield 56 has a limited range of movement along the major axis along the length of stylus 2 to accommodate compression from writing movements. With reference to FIGS. 3, 4A and 4B, stylus electronics printed circuit board (PCB) 60 inclosed in stylus body 64 is attached to stylus tip assembly (comprising stylus tip 50, brass sleeve 52 and insulation 54) by wire 58, which is bent to fit in a thru hole on the PCB 60 and soldered in position. Wire 58 is the electrical connection between stylus tip assembly (50, 52 and 54) and PCB 60 electronics as well as a mechanical link between stylus tip 50 and stylus activating zero travel switch 70. PCB 60 is held in position at the other end between two posts 84 and 86 which comprise part of zero travel switch 70. Additionally, PCB 60 is. wrapped in low friction teflon insulating material 61 which protects the circuitry located on PCB 60 from possible accidental shorting on stylus body tube 64 and prevents stylus PCB 60 from dragging on stylus body 64. In an alternative embodiment, PCB 60 is notched to permit wire 58 to be soldered directly to PCB 60. Further, the pressure required to activate the zero travel switch 70 can be varied by placing an "O" ring between shield 56 and PCB 60. Such an "O" ring places PCB 60 in compression thereby reducing the travel required to activate zero travel switch 70. Adjustment screw 72 is used to adjust the amount of pressure required to actuate switch 70. Positioned opposite the grip end of stylus is zero travel switch 70. This switch is positioned opposite of the grip so as to minimize the effect of switch noise on the stylus input signal and the stylus electronics. As illustrated in greater detail in FIG. 4B, PCB 60 is held between two posts 84 and 86. Two posts 84 and 86 are composed of a conductive material. In the preferred embodiment two posts 84 and 86 are made of brass. Two posts 84 and 86 are held in position by a post position retainer 82. Post position retainer 82 is made of an insulating material such as non-conductive plastic and possesses a relatively low coefficient of friction with respect to the material used for zero travel switch housing 76. Two posts 84 and 86 are connected to two wires 88 and 90, which are connected to circuit pads on PCB 60. The wires 88 and 90 are long enough to permit movement of PCB 60 so as not to obstruct the operation of stylus 2 when stylus tip 50 is compressed. Two posts 84 and 86, post position retainer 82, pressure sensitive elastic conductive material (PSECM) 80, PSECM holder 78 and take-up screw 72 are contained in the zero travel switch housing 76. PSECM 80 used in this switch is manufactured by PCK Elastomerics, Inc. Hatboro, Pa. 19040. By tightening take up screw 72 excess movement is removed from the stylus assembly, thus minimizing the travel required to activate zero travel switch 70. Set screw 74 secures the position of zero travel switch 70 within stylus body 64. Stylus end cap 66 fits onto the end of stylus 2 to seal the assembly. Stylus umbilical 68 feeds through the end of stylus end cap 66. To activate zero travel switch 70, the user touches stylus tip 50 to conductive surface 6. Pressure exerted from touching conductive surface 6, such as typical handwriting pressure, causes position retainer 82 (and thereby two posts 84 and 86) to transfer the pressure to PSECM 80 which is compressed. When PSECM 80 is compressed, the conductive particles suspended in the matrix make contact and conduct. The current conducted from power supply post 86 through PSECM 80 conducts normal to the surface contact point; therefore, for the current to reach the other post, PSECM holder 78 must be constructed of a conductive material to act as a conductive link in the current path between the two posts. For the preferred embodiment, PSECM holder 78 is. made of brass. The current is conducted normal to the surface contact point on PSECM 80 and is conducted through PSECM holder 78 where it conducts back through PSECM 80. At the point in PSECM 80 compressed by post 84 the current follows the normal path to post 84 which conducts the current to PCB 60. When the pressure is removed from stylus tip 50, the circuit is opened and the current is switched off. Stylus umbilical 68 carries four wires to PCB 60 inside of stylus body 64; +12 V, -12 V, signal and board ground (not explicitly shown). These wires connect to the specific circuit pad locations on PCB 60 per the specific design of PCB 60. Stylus umbilical 68 runs along the inside of the stylus body 64 through a slot (not shown) cut into zero travel switch body 76. All four wires are attached with enough length so as not to impair the movement of the internal components of stylus 2. Umbilical shielding 92 is connected to a stiff length of conductive material 93 (shown as a stiff spring) which contacts the inside of the stylus body 64 which functions to ground stylus body 64. In an alternative embodiment, additional wires are brought to stylus 2 through umbilical 68 in order to increase the variety of functions which are controlled by stylus 2. Differential amplifier 57 has been located in stylus 2 so as to permit the processing of the analog signal from conductive surface 6 at the closest point possible to the signal origin. Processing the signal at the signal source maximizes the signal to noise ratio and therefore minimizes the effect of any noise developed along stylus umbilical 68. Further, the combined noise reducing effects of electromagnetic shield 56 over stylus tip 50 and the design of plastic stylus grip 62 eliminate two paths that have the potential for introducing precision damaging noise into the system. For the preferred embodiment of the present invention an OPA37GU Wide-Bandwidth Operational Amplifier is used to perform the differential amplifier functions. The use and application of this operational amplifier for use as in the invention is known in the art and described in the Burr-Brown Product Data Book Supplement, which is hereby incorporated by reference. Further, PSECM 80 used in zero travel switch 70 does not produce an instantaneous voltage change. Zero travel switch 70 of the type as used in the preferred embodiment is connected to a conventional operational amplifier integrator, allowing lower switch power while maintaining equal rise and fall times, (included on PCB 60; not explicitly shown) which has a characteristic voltage ramping which is added to the signal from stylus tip 50 as a DC offset. Since instantaneous voltage changes are not present and the ramping is smooth, switching spikes, another source of unwanted noise, are eliminated. The signal received by stylus tip 50 is amplified before it is transmitted to the signal processing circuitry. In the preferred embodiment of the present invention, the amplified signal typically is 10 V peak to peak maximum. Increasing the voltage of the signal maximizes the signal to noise ratio thereby resulting in increased signal accuracy. Further, the slope (e.g., bandwidth) of signal 30 is limited by the operational amplifier integration in stylus 2 (not explicitly shown; more fully described above) to keep the energy of the information below the frequency of band pass filter 42. Spikes are created when the slope of the signal is not limited in bandwidth. The spikes distort the information on the input signal. When the signal is processed by band pass filter 42 the spikes are removed along with some of the information from the input signal. The consequent loss of information from the input signal compromises the precision of the system. By limiting the sloping of the signal, the present invention prevents high frequency spikes, which would otherwise distort the information being communicated from the stylus, thereby improving the precision of the present invention. While the above description of the preferred embodiment of the user input device refers to a stylus-type device, it is apparent to one skilled in the art that alternative input devices can be used in conjunction with the present invention while maintaining the spirit of the present invention. One form of alternative input device is an input device commonly referred to in the art as a "puck". The puck consists of two pieces of antenna wire mounted in a rigid frame, a conductive loop, or a disc of ITO coated mylar. The two antenna wires are used as cross hairs to locate the overlapping sections of the antenna wires over the desired target. While this form of input device provides an increase in system accuracy, it is not as conducive as stylus 2 to handwriting motion control of conductive surface 6. Referring to FIG. 2 input protection buffer 131, which is the preferred embodiment is comprised of National Semiconductor LM318 op amp, protects the system electronics from static charges. The op amp of input protection buffer 131 dissipates static charges accumulated on conductive surface overlay 6 and conducted through stylus 2. Still referring to FIG. 2, analog signal 30 is the amplified signal detected by electrostatic coupling 4, which is sensed by stylus 2 from conductive surface overlay 6. Analog signal 30 carries information on the location of stylus 2 with respect to conductive surface 6. Analog signal 30 also serves as input for stylus switch decoder 115. Since the switch frequency required by stylus switch decoder 115 is low, and band pass filter 42 does not pass frequencies in this range, stylus switch decoder 115 uses unprocessed stylus input signal 30. Stylus switch decoder 115 transmits 1 bit of switch information 152 indicating when stylus 2 is switched on or off (i.e., "pen up" not contacting conductive surface 6, "pen down" contacting conductive surface 6). Stylus switch signal 152 is transmitted from stylus switch decoder 115 to provide a signal that stylus 2 is writing ("pen down"). For the preferred embodiment of the present invention a National Semiconductor LM311 Voltage Comparator is used to perform the stylus switch decoder functions. The use and application of such a voltage comparator as in the present invention is known in the art and is described in the National Semiconductor Linear Data Book, which is hereby incorporated by reference. Calibration analog switch 38 is used to select a known input 128 to digital gain control 40. Sine wave signal 124 from power amplifier 34 and analog signal 30 from stylus 2 are the two input sources from which calibration analog switch 38 selects input 128 for digital gain control 40. During normal operation, calibration analog switch 38 transmits the stylus analog signal 30 to digital gain control 40. During the calibration of digital gain control 40, calibration analog switch 38 transmits the signal from power amplifier 34, serving as a reference signal, to digital gain control 40. Use of the calibration switch 38 results in a known relationship between each of the sixteen (16) gain settings. Calibration analog switch 38 in the preferred embodiment of the present invention is an HI201HS High Speed Quad SPST CMOS Analog Switch. The use an application of such an analog switch is known in the art and described in the Harris Corporation Analog and Telecommunications Product Data Book, which is hereby incorporated by reference. The output from calibration analog switch 38 provides the reference signal input for digital gain control 40 as described above. Digital gain control 40 adjusts the amplitude of stylus signal 128 based on the four (4) bit gain setting information simultaneously received from microprocessor 110 via microprocessor ports 108. Four (4) bit gain setting signal 162 from microprocessor 110 determines the gain used by digital gain control 40. Since the relative gains are known to a high degree of precision the relative gain for each drive direction can be factored out. In the preferred embodiment the gain ranges from 1 to 16. Digital gain control 40 serves to maximize the available range of analog to digital converter 104. Microprocessor 110 is able to independently vary the gain setting for each drive direction of conductive surface 6. Microprocessor 110 independently controls the gain setting for each drive direction by using four analog switches to four (4) different resistors as dictated by software controlling microprocessor 110. Controlling the gain independently for each drive direction the system uses the narrowest possible pass band. Since the pass band is proportional to the rejection of stochastic noise, narrowing the pass band permits maximizing the rejection of noise. In the preferred embodiment, an HI201 Quad SPST CMOS Analog Switch is used to preform the switching used in the digital gain control function. The use and application of such an analog switch as in the present invention is known in the art and described in the Harris Corporation Analog and Telecommunications Product Data Book, referenced above. Referring to FIG. 2, the sinusoidal waveform output 126 from sine wave generator 36 provides a highly consistent amplitude waveform. The consistency and precision of sinusoidal. waveform output 126 with the addition of controlled gain, provides a high signal to noise ratio. Band pass filter 42 is used to further improve the signal to noise ratio, and thereby improve the precision of the system. Band pass filter 42 narrows the bandwidth of the signal which rejects the noise on the signal. In the preferred embodiment, band pass filter 42 accepts signals whose spectrum occupies a very narrow band range in the vicinity of 250 kHz (i.e., approximately the frequency of sinusoidal waveform output 126) and attenuates any other signals. Band pass filter 42 input is designed to set the pass band approximately equal to the frequency of sinusoidal waveform output 126. This frequency selective network allows only specified frequency signals 132 to pass, and all components having frequencies outside of the pass band are attenuated. In the preferred embodiment, band pass filter 42 is a 2-pole, fourth order Butterworth filter, comprised of an LM318 Operational Amplifier and a connected resistive/capacitive network. The use of operational amplifier resistors and capacitor to build band pass filters such as band pass filter 42 is known in the art and described, for example, to the National Semiconductor Linear Data Book, referenced above. Variable timing generator (VTG) 14 in FIG. 1 consists of state machine 114 and control signal driver 112. State machine 114 contains a high frequency oscillator, 16-bit binary counter, and decoder logic which decodes the output signals of the binary counter (all not explicitly shown). The frequency of the oscillator is sufficiently high (e.g. 20 Mhz) to insure that the alternating field generated by the surface can be measured easily by the capacitively coupled stylus 2. All components in the variable timing generator are commercially available parts, and they are interconnected in a conventional manner. The decoder logic can be constructed of look-up table PROM's, PAL's or sequential logic components. The system of the present invention has been designed to control offsets. Controlling offsets improves the accuracy of the system signal and hence a more accurate signal produces a more accurate result from the integrator. Several controllable offsets are listed with the corresponding the effect on the system signal and the hardware which has been designed for quantifying these offsets, coupling and unwanted effects. 1. Referring to FIG. 10 at point 203, offset due to the difference between the ADC zero scale voltage and the integrator reset voltage which has a constant effect on the system signal. This offset is quantified using calibration analog switch 38 shown in FIG. 2. 2. Hold step and droop rate which is directly associated with the sample and hold amplifier. Occurring at point 218 on FIG. 10, this offset has a constant effect on the integrator signal and is very similar to #1 above. Effects #1 and #2 are not readily distinguishable, however, since neither is a function of time. If the sum of effects #1 and #2 can be calculated, then these signals can be subtracted from the integrator signal. This offset is quantified by varying digital gain control 40 using signal 124. 3. Integrator input offset which occurs during integration or reset and has a time dependent effect on the system signal. This offset is quantified using rectifier output switch 46 controlled by signal 138. 4. Half wave rectifier output offset which occurs during the integration of the input signal. This offset has a time dependent effect on the system signal. 5. Half wave rectifier input offset which occurs during the integration of the input signal. This offset has a time dependent effect on the system signal. This offset is quantified by shutting off the overlay using signal 48 via 112. 6. Unwanted coupling from power amp 34 to ASP 28 elements. This coupling is always present when driving the overlay and has a time dependent effect on the system. Coupling is controlled by varying the integration time. 7. Offset in gains throughout the system which is amplitude dependent. 8. Band pass at the band pass filter. If the pass band is too narrow the amplitude during the previous drive direction will effect the present integration cycle. Integrator 102 measures the area between the half-wave rectified, filtered signal 158 and ground potential. Output signal 155 of integrator 102 varies proportionally to the area between the signal and ground. In the preferred embodiment of the present invention, integrator 102 is an AD585 High Speed Precision Sample-and-Hold Amplifier. The use and application of such a sample-and-hold amplifier is known in the art and denoted in the Analog Devices AD585 Data Sheet, which is hereby incorporated by reference. Since the integrator is a sample and hold amp and functions as such, it thus eliminates the need for a sample and hold amplifier between the integrator and the ADC. If the ADC used were too slow, adding a sample hold amp would allow simultaneous integration and analog to digital conversion for compensation. Rectifier output switch 46 connects and disconnects half-wave rectifier 44 and integrator 102. Rectifier output switch 46 has two control inputs, one input 136 from state machine 114, and another input 138 from microprocessor 110 via microprocessor ports 108. Rectifier output switch 46 is turned on only when both controls are active. When state machine 114 is resetting integrator 102, state machine 114 turns rectifier output switch 46 off. When microprocessor 110 is measuring the DC offset of half-wave rectifier 46 and integrator 102 for a specific integration time, microprocessor 110 turns rectifier output switch 46 off. In an alternative embodiment, the integration time can be uniquely variable for each drive direction. If the amplitude of signal 158 coming into integrator 102 is approximately equal for each of the four drive directions, through digital gain control, only selection of the length of a common integration time for each drive direction is required. Further, microprocessor 110 is able to maintain minimum changes in the amplitude of signal 130 into band pass filter 42 by controlling the gain uniquely for each drive direction. Since the width of the pass band is inversely proportional to the time for the signal to decay, and the step size is proportional to the time for the signal to decay, the closer the input signal gain is to the band pass filter, less signal decay time is needed. By minimizing the time for the signal to decay the number of samples can be maximized which in turn allows the present invention to sense the location of stylus 2 more often, thereby increasing accuracy while maintaining precision. Analog to digital converter (ADC) 104 converts analog signal 155 to equivalent digital data output 167. ADC 104 of the preferred embodiment of the present invention is a Philips TDA1534 14-bit Analog to Digital Converter, use and application of such an ADC is known in the art and is described in the Signetics Linear Data Manual Vol.2 Industrial, which is hereby incorporated by reference. ADC 104 receives a timing control signal 168 from state machine 114. Timing control signal 168 is synchronized with integrator 102 control signal 160 such that when integrator 102 receives a signal 160 to stop integrating, ADC 104 receives a signal 168 to convert analog signal 155 to digital data for processing by microprocessor 110. Digital output 167 from ADC 104 is routed to microprocessor 110 by microprocessor ports 108 via microprocessor bus 150. Digital output 167 from ADC 104 provides microprocessor 110 with coordinate information, while 2-bits of encoded drive information 142 specifies to microprocessor 110 which direction of conductive surface 6 was driven when the information was gathered. Microprocessor 110 functions to coordinate and control the elements of the present invention. In the preferred embodiment, microprocessor 110 is an Intel 80186. The use and application of microprocessors such as microprocessor 110 of the present invention is know in the art and is described in, for example, the Intel; APX 86/88, 186/188 Users's Manual (Hardware Reference and Programmer's Reference) and Intel Microsystem Components Handbook Microprocessor Volume I, which are hereby incorporated by reference. If microprocessor 110 has sufficient time to perform calculations to maintain small amplitude changes in output signal 130 of digital gain control 40, via 4-bit gain control setting 162, the bandwidth of the pass band of band pass filter 42 can be reduced. This increases the performance of the present invention since minimizing the width of the pass band by band pass filter 42, given that the frequency spectral content of noise in the system is essentially limited to the pass band, thus allows the relative amount of noise imposed on the system to be reduced. This filtering process removes noise picked up along the umbilical of stylus 2 without reducing the data content of the signal transmitted from stylus 2. In alternative embodiments of the present invention, hardware is included that maintains small amplitude changes at a given output. Such hardware (not explicitly shown) would be comprised of digital logic using multipliers and essentially perform the functions of what is known in the art as an arithmetic logic unit (ALU) (not shown). This specialized ALU would be able to maintain the gains, keep track of the times of integration, and output data from the analog to digital converter (ADC). Using the timing and output data, the gain for small amplitude changes could be determined. The advantage of such hardware is to free microprocessor 110 to dedicate all available time to other processing functions. While the present invention has been described largely in terms of a planar and rectilinear coordinate system, it would be apparent to one skilled in the art that other conductor shapes and coordinate systems may be employed without departing from the spirit of the present invention. For example, portions of spheres or cylinders may be employed rather than a flat plane. In addition, while typical uses of this improved high precision coordinate sensing method and apparatus require active areas of several square feet, the present invention can be successfully employed with very large sensors spanning tens of square feet. For such large sensors, the maximum stylus distance from the conductive surface is greater than several feet. Additionally, many small overlays working in concert to emulate a single large overlay, each having the accuracy and precision of a single large overlay, can be used to multiply the precision and accuracy of the system. Further, while the present invention has been described largely as a coordinate sensing device which is used in conjunction with a single display device, it would be apparent to one skilled in the art that this invention can be used to control several display devices by allocating a specific control area to each of the control devices used. Such an allocation of control area is presented in copending application U.S. patent application Ser. No. 914,924 (the "924 application"), filed Oct. 3 1986, now abandoned, by Jakobs, et al., for "A Integrated Multi-display Overlay-Controlled Communicating Workstation", which is hereby incorporated by reference. Additionally, the allocation of designated control areas of conductive surface 6 can be implemented for use with non-planar non-rectilinear surfaces as described above. Another alternative embodiment of the present invention utilizes a single stylus 2 over n-tuple conductive surfaces (multiple conductive surfaces such as conductive surface 6). For example, one or more surfaces act as a control area for the system while the remaining surfaces are mounted on display devices. The n-tuple displays working in concert are advantageous in that one stylus controls all of the displays and the system is highly functionally integrated with the system. Use of a single stylus over n-tuple conductive surfaces is described in the '231 Patent. Although the invention has been described in terms of a preferred embodiment, and various alternative embodiments, it will be obvious to those skilled in the art that many alterations and modifications may be made without departing from the invention. Accordingly, it is intended that all such alterations and modifications be included within the spirit and scope of the invention as defined by the appended claims.

An improved high resolution method and apparatus are described for sensing and determining the spatial coordinates of a movable object with respect to a energized conductive surface. The coordinates of the object are precisely measured with respect to a two-dimensional coordinate system independent of the third orthogonal dimension, thereby avoiding significant measurement errors due to variations of the object position in the third orthogonal dimension. The system also ascertains the coordinate position of the object in this third dimension, which can then be utilized as an independent control variable in the system. Further, the system can accommodate a number of energized conductive surfaces over which the object may be positioned and can determine the spatial coordinates of the object with respect to any such surface. In general, the system of the present invention can ascertain the generalized n-tuple position vector of the object with respect to each of a plurality of generalized, energized conductive surfaces. In any of the foregoing forms, the energized conductive surfaces can be transparent. The system described improves the precision and accuracy of the location of the selected point and hence the precision and accuracy of the spatial coordinates calculated by the system for display. The improvement in system performance is the result of innovations in fundamental design concepts utilized throughout the system.

FIELD OF THE INVENTION This invention relates to an oligopeptide derivative having amphiphatic properties when bound to a hydrophobic group, a liposome and a monolayer each comprising said oligopeptide derivative as a film component. BACKGROUND OF THE INVENTION A liposome is a closed vesicle comprising a lipid bimolecular film. It is considered that a natural biomembrane has a lipid bimolecular structure and thus liposomes have been widely used as a biomembrane model in studies on physicochemical properties of biomembranes. Furthermore, a number of substances can be enclosed in the internal aqueous layer or within the membrane of a liposome and then fused with a cell or incorporated into a cell. Thus liposomes have been used as a carrier for transporting substances to and into cells. Attempts have been widely made to apply liposomes to various purposes in the fields of, for example, biology, medicine and pharmacology, so as to employ liposomes as a carrier for transporting enzymes or cancerocidal substances, to use liposomes for immunological purposes, to utilize the interaction of liposomes with cells or to apply liposomes as a drug delivery system. Although liposomes are widely applicable to various purposes as described above, it has been recognized that liposomes have a brittle membrane structure, such that a chemical or physical change, in the lipids, constituting the membrane, causes some irreglularities in the orientation of the membrane. This brings about the leakage of the content of the liposomes, or the association or aggregation of liposomes with each other. As a result, a precipitate is formed. In order to overcome this problem, a number of attempts to form a vesicle using synthetic amphiphatic compounds as analogs of naturally occurring phospholipids have been reported (refer to, for example, "Liposome," ed. by Nojima, Sunamoto and Inoue, Nankodo, Chap. 8). However none of the vesicles thus obtained is satisfactory as a drug carrier from the viewpoint of stability and lack of toxicity to the human body. Known examples of an amphiphatic compound having an oligopeptide in the hydrophilic moiety and two long-chain alkyl groups in the hydrophobic moiety include those reported by Ihara et al. [Polym. Commun., 27, 282 (1986); Polymer J., 18, 463 (1986); Chem. Lett., (1984), 1713; and J. Jap. Chem., (1987), 543] and reported by Shimizu et al. (Chem. Lett., (1989), 1341; Thin Solid Films, 180 (1989), 179; JP-A-2-69498 and JP-A-2-71836] (the term "JP-A" as used herein means an "unexamined published Japanese patent application"). However none of these amphiphatic compounds is suitable as a drug carrier, since either it fails to form a vesicle of a monolayer or monolayer vesicle, if formed, is easily converted into other structures. On the other hand, it is expected that molecular assemblies comprising a monolayer having a molecular orientation or multilayers, which are ultra-thin and dense, are widely applicable to materials for electronics devices and materials for protecting surfaces as well as to functional films for sensors based on the selective permeability of a gas molecule or an ion and permeation-controlling films for delivering materials. The Langmuir-Blodgett ("LB") technique has been commonly known as a method for laminating a monolayer comprising amphiphatic compound molecules formed on a gas/liquid interface on a substrate. Recently, various LB films produced by this technique have been widely employed as organic ultra-thin films [refer to Kotai Butsuri, 17 (12), 45 (1982)]. Although molecular assemblies including LB films exert various functions based on the orientation of molecules and the ultra-thin properties, they have a highly delicate film structure from a physical standpoint and thus are liable to degradation or decomposition. It is observed in the cases of some of such compounds, furthermore, that the film structures suffer from many defects or irregularities and thus high density cannot be achieved. Therefore it is required for all uses to physically strengthen the film structures of these molecular assemblies to thereby provide uniform and highly dense films. An effective means for physically strengthening the film structure of a molecular assembly is crosslinkage or polymerization of molecules. Relating to the polymerization of, for example, LB films, conventional polymerizable compounds and polymerization modes are summarized by H. Bader et al. [Advances in Polymer Science, 64, 1 (1985)] and R. Buschl et al. [Macromol. Chem. Suppl., 6, 245 (1984)]. Polymerizable amphiphatic compounds have been frequently investigated. At the early stage of these studies, the major means employed comprised polymerizing unsaturated vinyl diene and diacetylene compounds, which were selected as polymerizable compounds, by irradiation using UV or rays such as γ-rays. Although the polymers obtained by these methods had fast structures, the order of the molecular arrangement was poorly maintained after cleavage of unsaturated bonds. As A. Laschewsky and H. Ringsfdorf [Macromolecules, 21, 1936 (1988)] point out, the number of well-ordered polymerizable compounds is very limited, because the orientation of a film is significantly affected by the length of an alkyl chain and the terminal hydrophilic group. A. Laschewsky et al. further disclose [J. Am. Chem. Soc., 109, 788 (1987)] that polymerizable groups in various amphiphatic compounds having unsaturated bonds, which are useful in, for example, radiation polymerization, should be kept via spacer groups in order to maintain the order of molecular arrangement. Furthermore, JP-A-57-159506 shows an example of the application of a monolayer and multilayer polymeric film of an unsaturated compound (surfactant) produced via radiation polymerization as an ultrafiltration membrane. Known techniques for polymerizing these compounds having unsaturated bonds via radiation suffer from the following problems. Namely, one problem resides in the fact that a specific molecular design strategy (for example, inserting a spacer group) is required in order to avoid some irregularities in the molecular orientation or irregular aggregation and precipitation of molecules caused by the polymerization. A second problem resides in the fact that the irradiation with UV or γ-ray would frequently induce the decomposition or denaturation of various additives which are present together with the polymerizable amphiphatic compounds. A third problem resides in the fact that the film thus obtained via such a polymerization usually has extremely poor biocompatibility, which restricts the types and number of applications of such a product in living tissues to, for example, a permeation-controlling membrane for drugs. Therefore, J. Am. Chem. Soc., 109, 4419 (1987) proposes a method for forming disulfide bond via the oxidative polymerization of dithiol without using radiation. Alternately, it is effective to radical-polymerize the above-mentioned compounds having unsaturated bonds in the presence of an initiator. In these methods, however, an initiator used at the polymerization needs to be removed from the film system after completion of the polymerization. In addition, the effects of the uses of an initiator involving redox agents on coexisting substances should be taken into consideration which initiator may have optimental effects on other components of such films. Furthermore, the condensation polymerization of a molecular film of an amino acid derivative has been attempted in the presence of carbodiimide in order to improve the polymerization mode and enhance the biocompatibility [refer to J. A., Chem. Soc., 108, 487 (1986).] However this method cannot be easily performed too, since there is a problem of the residual condensing agent and by-products and it is required to control the efficiency of the condensation reaction. SUMMARY OF THE INVENTION It is an object of the present invention to provide an oligopeptide derivative, to which amphiphatic properties are imparted by binding to a hydrophobic group capable of forming a stable monolayer liposome, having the properties of showing negligible leakage of a drug contained therein and scarcely suffering from association, aggregation and precipitation, as well as an intermediate thereof. It is another object of the present invention to provide a liposome which comprises the oligopeptide derivative as a film component and which shows little leakage of a drug contained therein. It is another object of the present invention to provide a highly dense and substantially faultless film by taking advantage of the two-dimensional orientation formed by intermolecular hydrogen bonds of an oligopeptide incorporated in lipid molecules, different from the polymerization effected in the above-mentioned conventional methods. Furthermore, it is another object of the present invention to provide a film which has excellent biocompatibility and is suitable for carrying biosubstances such as proteins. These objects of the present invention have been achieved by a compound or N-terminal salt thereof represented by the general formula (I), a liposome comprising said compound as a film component or a monolayer or multilayers comprising the compound of the general formula (I). ##STR2## In the above general formula (I), R 1 and R 2 represent each a straight-chain, branched alkyl or acyl group having 8 to 24, and preferably 12, 14, 16 or 20, carbon atoms, optionally having a substituent or an unsaturated group. Substituent groups can be, e.g., alkylcarbonyl groups, alkoxycarbonyl groups, halogen atoms and aryl groups. Unsaturated groups can contain double and triple bonds wherein two or more unsaturated bonds may be present in each of R 1 and R 2 . Examples of R 1 and R 2 , which can be the same or different, include dodecyl, tetradecyl, hexadecyl, myristoyl and palmitoyl groups. X can represent --0-- or --NH --. R 3n and R 3 (n+1) can each represent a side chain of an α-amino including a side chain of one of the of 20 α-amino acids occurring in nature (refer to, for example, Creighton, "PROTEINS," Freeman Co. (1984)) and analogues and derivatives thereof. Preferable examples thereof among amino acid side chains according to the present invention include a hydrogen atom, and side chain residues of amino acids which are more hydrophilic than glycine, for example, ##STR3## In R 3 (n+1), (n+1) is a number of one figure. When n=5, for example, R 3 (n+1) corresponds to R 36 . R 31 , R 32 , , R 3 (n+1) may be either the same or different from each other. n is an integer of from 0 to 5, preferably 0, 1, 2 and 3. An asymmetric carbon atom can be present in the compound and the compound can be either a racemic compound or an optically active one. It is frequently advantageous, from the viewpoint of stability or handling, that the amino group at the terminal of the molecule forms a salt together with an appropriate acid component. Preferable examples of the acid component include trifluoroacetic acid, hydrogen chloride and hydrogen bromide. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing the 1 H NMR spectrum of the intermediate 5C [a compound involved in the general formula (II)] of the compound (5) described in Synthetic Example 15. FIGS. 2 and 3 are graphs each showing the extent of leakage of a content included in a liposome. FIGS. 4 to 9 are graphs each showing the relationship between the surface pressure vs. molecular occupation area of a monolayer. DETAILED DESCRIPTION OF THE INVENTION Examples of the compound represented by the general formula (I) are given below, although the present invention is not be construed as limited thereby. __________________________________________________________________________Compound R.sup.1 R.sup.2 R.sup.31 R.sup.32 R.sup.33 R.sup.34 HB X__________________________________________________________________________ ##STR4## (1) C.sub.14 H.sub.29 C.sub.14 H.sub.29 H HCl O (2) " " CH.sub.2 OH HCl O (3) " " CH.sub.2 CO.sub.2 H HCl NH ##STR5## (4) C.sub.14 H.sub.29 C.sub.14 H.sub.29 H HCl NH (5) C.sub.14 H.sub.29 C.sub.14 H.sub.29 H CF.sub.3 CO.sub.2 NH (6) C.sub.14 H.sub.29 C.sub.14 H.sub.29 H HCl O O H (7) C.sub.14 H.sub.29 C.sub.14 H.sub.29 CH.sub.2 CNH.sub.2 CF.sub.3 CO.sub.2 O (8) C.sub.14 H.sub.29 C.sub.14 H.sub.29 H CF.sub.3 CO.sub.2 O (9) C.sub.16 H.sub.33 C.sub.16 H.sub.33 H CF.sub.3 CO.sub.2 O(10) C.sub.16 H.sub.33 C.sub.16 H.sub.33 H HCl O(11) ##STR6## ##STR7## H CF.sub.3 CO.sub.2 O(12) ##STR8## ##STR9## H HCl O(13) C.sub.14 H.sub.29 C.sub.14 H.sub.29 CH.sub.2 OH HCl O(14) ##STR10## ##STR11## H HCl O(15) ##STR12## ##STR13## H CF.sub.3 CO.sub.2 O ##STR14##(16) C.sub.14 H.sub.29 C.sub.14 H.sub.29 H H CF.sub.3 CO.sub.2 O(17) " " " CH.sub.2 OH " O(18) C.sub.16 H.sub.33 C.sub.16 H.sub.33 H H HCl O(19) C.sub.14 H.sub.29 C.sub.14 H.sub.29 CH.sub.2 OH CH.sub.2 OH HCl O(20) ##STR15## ##STR16## H H CF.sub.3 CO.sub.2 O(21) C.sub.14 H.sub.29 C.sub.14 H.sub.29 H CH.sub.2 CO.sub.2 H -- O(22) " " H H HCl O(23) " " H ##STR17## CF.sub.3 CO.sub.2 O(24) ##STR18## ##STR19## H CH.sub.2 OH HCl O(25) ##STR20## ##STR21## H ##STR22## CF.sub.3 CO.sub.2 O(26) C.sub.14 H.sub.29 C.sub.14 H.sub.29 H CH.sub.2 CH.sub.2 CH.sub.2 CH.sub.2 NH.sub.2 CF.sub.3 CO.sub.2 NH(27) C.sub.12 H.sub.25 C.sub.12 H.sub.25 H CH.sub.2 CH.sub.2 CO.sub.2 H -- O ##STR23##(28) C.sub.14 H.sub.29 C.sub.14 H.sub.29 H H H CF.sub.3 CO.sub.2 O(29) " " " " CH.sub.2 OH HCl O(30) " " " " H HCl NH ##STR24##(31) C.sub.14 H.sub.29 C.sub.14 H.sub.29 CH.sub.2 OH CH.sub.2 OH HCl O(32) C.sub.16 H.sub. 33 C.sub.16 H.sub.33 CH.sub.2 OH CH.sub.2 OH HCl O(33) ##STR25## ##STR26## CH.sub.2 OH CH.sub.2 OH HCl O__________________________________________________________________________ The amphiphatic compound of the present invention may be prepared using known methods, e.g., by synthesizing an oligopeptide moiety whose N-terminal and side chain are blocked, and then condensing the obtained product with glycerol substituted at the 1- and 2-positions [general formula (III}] or an amino derivative thereof [a compound of general formula (II) wherein Y is a hydrogen atom]. Alternately, compounds represented by the general formula (II) or (III) may be successively condensed with amino acids whose N-terminii and side chains are blocked [the former method is called a fragment condensation method, while the latter one is called a stepwise elongation method, refer to Izumiya et al. "Peptide Gosei no Kiso to Jikken," Maruzen, Chap. 8 (1985).] ##STR27## wherein R 1 and R 2 are the same as those defined in general formula (I); and each compound can be either a racemic compound or an optically active one regarding the asymmetric carbon atom in the molecule. Compounds of the general formula (II) are useful as an intermediate of the compound of the general formula (I). Compounds represented by the general formula (III) may be synthesized known methods, for example, by a method described in J. Am. Chem. Soc., 63, 3244 (1941). Alternately, a commercially available compound may be employed. Compounds of general formula (II), wherein Y is a hydrogen atom, can be synthesized using known methods, e.g., by converting the hydroxyl group of the compound of the general formula (III) into an amino group, for example, by methods described in "Shin Jikken Kagaku Koza", ed. by J. Soc. of Chem., 14 (III), 1332-1399 (Maruzen) (1978). Typical examples of such known methods include (1) converting the hydroxyl group into a p-toluenesulfonate followed by substituting with phthalimide potassium or treating with hydrazine (Gabriel's method); and (2) substituting the p-toluenesulfonate with an azide followed by hydrogenating. Compounds represented by the general formula (II), wherein Y is a hydrogen atom, can be purified and preserved in the form of salts together with an appropriate acid component, since such compounds are generally in a waxy state and thus are difficult to purify and, furthermore, easily undergo transacylation when R 1 and R 2 are acyl groups. Preferable examples of acid components include trifluoroacetic acid, acetic acid, hydrogen chloride and hydrogen bromide. When the amino group is protected, the aforesaid problems would be scarcely observed. Preferable examples of the protecting groups include t-butyloxycarbonyl (tBoc) group and benzyloxycarbonyl (CBZ) group. Now Examples of compounds according to the present invention will be given. Amino acids and abbreviations thereof are in accordance with those commonly employed in the art [refer to, for example, "Peptide Gosei no Kiso to Jikken," ed. by Izumiya et al., (Maruzen), as cited above.] "A liquid crystal phase transition point" as used hereinafter means the temperature at which a crystal phase melts to become a liquid phase, which was measured by using DSC 100 (produced by Seiko Instruments Inc.). SYNTHETIC EXAMPLE 1: SYNTHESIS OF COMPOUND (8) Commercially available GlyGly was converted into amino group protected tBoc-GlyGly in accordance with known methods, e.g., as described in "Peptide Gosei no Kiso to Jikken," ed. by Izumiya et al., (Maruzen). 1.39 g (6 mmol) of tBoc-GlyGly, 2.42 g (5 mmol) of 1,2-o-ditetradecyl-syn-glycerol and 60 mg of N,N-dimethylaminopyridine were dissolved in 20 ml of DMF (N, N-dimethylformamide) and 10 ml of methylene chloride. To the solution thus formed, was added 1.3 g of DCC (dicyclohexylcarbodiimide) under cooling with water and stirring. Then the mixture was stirred at room temperature for 24 hours. The dicyclohexyl urea thus precipitated was filtered and methylene chloride was distilled off from the filtrate under reduced pressure. 50 ml of ethyl acetate was added to the residue followed by successively washed with a 10% aqueous solution of citric acid, with water and saline and separating. The dicyclohexyl urea precipitated again in the ethyl acetate phase and was filtered to produce a filtrate which was then concentrated. Then the residue from the concentrated filtrate was purified by silica gel chromatography (n-hexane/ethyl acetate=2/1) to thereby give 3.37 g (4.8 mmol) of the compound (8) in a tBoc-protected form having a yield of 90%. 3.37 g of this protected product as compound (8) was dissolved in 60 ml of methylene chloride. After adding 30 ml of trifluoroacetic acid, the mixture was stirred at room temperature for 30 minutes. Then the solvent methylene chloride was distilled off under reduced pressure and the residue was recrystallized from a solvent mixture (ethyl acetate/acetonitrile =1/1) to thereby give 2.87 g (4.03 mmol) of the compound (8) having a yield of 84% and a liquid crystal phase transition point of 79 ° C. SYNTHETIC EXAMPLE 2: SYNTHESIS OF COMPOUND (16) tBoc-GlyGly synthesized n the above Synthetic Example 1 was condensed with commercially available Gly-oBzl p-toluenesulfonate by DCC. Further, the obtained condensate was hydrogenated with 10% palladium carbon to thereby give tBoc-GlyGlyGly. Starting from 2.2 g (8 mmol) of the tBoc-GlyGlyGly and 3.88 g (8 mmol) of 1,2-o-ditetradecyl-syn-glycerol, the procedure of Synthetic Example 1 was repeated. After purifying by silica gel column chromatography (ethyl acetate/chloroform =3/2), 4.35 g (5.75 mmol) of the compound (16) was obtained in a tBoc-protected form, having a yield of 72%. Then the protecting group was removed by treating with trifluoroacetic acid, similar to Synthetic Example 1. After recrystallizing from ethyl acetate, 4.3 g (5.58 mmol) of the compound (16) was obtained having a yield of 97% and a liquid crystal phase transition point of 97° C. SYNTHETIC EXAMPLE 3: SYNTHESIS OF COMPOUND (20) Starting from 1.37 g (5 mmol) of tBoc-GlyGlyGly as prepared in Synthetic Example 2 above, and 2.56 g (5 mmol) of 1,2-o-dimyristoyl-syn-glycerol, the procedure of Synthetic Example 1 was repeated. After purifying by silica gel column chromatography (ethyl acetate/chloroform =25/10), 2.9 g (3.7 mmol) of the compound (20) was obtained in a tBoc-protected form having a yield of 74%. Then the protecting group was removed from 2.8 g (3.87 mmol) of the protected product by treating with trifluoroacetic acid, according to Synthetic Example 1. After recrystallizing from ethyl acetate, 2.58 g (3.23 mmol) of the compound (20) was obtained, having a yield of 91% and a liquid crystal phase transition point of 88° C. SYNTHETIC EXAMPLE 4: SYNTHESIS OF COMPOUND (9) The same condensation and deprotection procedures as those described in Synthetic Example 1 were performed except that the 1,2-o-ditetradecyl-syn-glycerol was replaced with 1,2-o-dihexadecyl-syn-glycerol to obtain compound (9) having a liquid crystal phase transition point of 82° C. SYNTHETIC EXAMPLE 5: SYNTHESIS OF COMPOUND (17) 1.06 g (3.6 mmol) of tBoc-L-Ser(Bzl) was dissolved in 15 ml of methylene chloride. "Bzl" as used herein means a benzyl group. After adding 0.74 g of DCC, the mixture was stirred at room temperature for 30 minutes. Next, a methylene chloride solution containing 2.14 g (3 mmol) of compound (8) and 4.20 μ1 (3 mmol) of triethylamine was added and the mixture was stirred at room temperature for 8 hours. The dicyclohexyl urea thus precipitated was filtered and the filtrate was concentrated. The residue from the filrate was purified by silica gel chromatography (n-hexane/ethyl acetate =1/1) to give 2.0 g (2.28 mmol) of the compound (17) was obtained in a tBoc-protected form, having a yield of 76%. 1.9 g of this protected product was dissolved in 20 ml of methylene chloride. After adding 10 ml of trifluoroacetic acid, the mixture was stirred at room temperature for 30 minutes to remove the tBoc protecting group. After the completion of the stirring, the solvent was distilled off under reduced pressure. 20 ml of methanol and 150 mg of 10% palladium carbon were added to the residue and the mixture was hydrogenated at 30° C. under atmospheric pressure for 8 hours. After filtering off the catalyst, the filtrate was concentrated under reduced pressure. Then the residue was recrystallized from acetonitrile to thereby give 1.62 g (2.02 mmol) of the compound (17) having a yield of 93% and a liquid crystal phase transition point of 96° C. SYNTHETIC EXAMPLE 6: SYNTHESIS OF COMPOUND (23) 680 mg of DCC was added to a solution of methylene chloride (15 ml) and DMF (15 ml) containing 766 mg (3.3 mmol) of tBoc-L-Asn, 2.14 g (3 mmol) of the compound (8), 505 mg (3.3 mmol) of N-hydroxybenztriazole monohydrate and 420 μ1 (3 mmol) of triethylamine. The mixture was then stirred at room temperature for 7 hours. After filtering the dicyclohexyl urea thus precipitated, the methylene chloride was distilled off from the filtrate under reduced pressure. Then 30 ml of ethyl acetate was added to the residue followed by successively washing with a 4% aqueous solution of sodium hydrogencarbonate, water and saline to separate. The ethyl acetate was distilled off under reduced pressure and the residue was purified by silica gel column chromatography (chloroform/methanol =10/1). Thus 2.08 g (2.56 mmol) of the compound (23) was obtained in a tBoc-protected form having a yield of 85%. 1.3 g (1.6 mmol) of this protected product as compound (23) was then dissolved in 15 ml of methylene chloride. After adding 7 ml of trifluoroacetic acid, the mixture was stirred at room temperature for 30 minutes. Then the solvent was distilled off under reduced pressure and the residue was recrystallized from acetonitrile. Thus 1.22 g (1.48 mmol) of the compound (23) was obtained having a yield of 92% and a liquid crystal phase transition point of 69° C. SYNTHETIC EXAMPLE 7: SYNTHESIS OF COMPOUND (21) The same condensation reaction as the one described in Synthetic Example 5 was performed except that 1.06 g (3.6 mmol) of the tBoc-L-Ser(Bzl) was replaced with 1.3 g (3.6 mmol) of Z-L-Asp(OBzl). After purifying by silica gel column chromatography (n-hexane/ethyl acetate =1/1), 1.6 g (1.7 mmol) of the compound (21) was obtained in a protected form having a yield of 57%. 1.5 g (1.6 mmol) of this protected product as compound (21] was dissolved in a solvent mixture comprising 10 ml of ethyl acetate and 20 ml of methanol. After adding 160 mg of 10 % palladium carbon, the mixture was hydrogenated at 30° C. under atmospheric pressure for 4 hours. After completion of the hydrogenation, 20 ml of methanol and 50 mol of DMF were added and the mixture was heated to 80° C. The crystals thus precipitated were dissolved and the catalyst was filtered off. The filtrate was cooled with ice and the precipitate was collected by filtering. After washing with ethyl acetate, 400 mg (0.56 mmol) of the compound (21) was obtained having a yield of 35% and a liquid crystal phase transition point of 117° C. SYNTHETIC EXAMPLE 8: SYNTHESIS OF COMPOUND (28) The same condensation reaction as the one described in Synthetic Example 6 was performed, except that the tBoc-L-Asn was replaced with 770 mg (3.4 mmol) of the tBoc-GlyGly synthesized in Synthetic Example 1. After purifying by silica gel column chromatography (chloroform/methanol =20/1), 2.0 g (2.46 mmol) of the compound (28) was obtained in a tBoc-protected form having a yield of 82%. 1.9 g (2.34 mmol) of this protected product as compound (28) was dissolved in 20 ml of methylene chloride. After adding 10 ml of trifluoroacetic acid, the mixture was stirred at room temperature for 30 minutes. Then the solvent was distilled off under reduced pressure and the residue was recrystallized from ethyl acetate. Thus 1.64 g (1.98 mmol) of the compound (28) was obtained having a yield of 85% and a liquid crystal phase transition point of 137° C. SYNTHETIC EXAMPLE 9: SYNTHESIS OF COMPOUND (22) 4.3 g (5.58 mmol) of the compound (16) synthesized in Synthetic Example 2 was dispersed in 50 ml of ion-exchanged water. After adding 15 ml of 1 N aqueous solution of sodium hydroxide, the mixture was extracted with 300 ml of ethyl acetate and separated. The ethyl acetate phase was washed with water and saline, dried ovr magnesium sulfate and then concentrated under reduced pressure to thereby give a volume of approximately 30 ml. After cooling with ice, the crystals thus precipitated were collected by filtering. Thus 1.4 g (2.13 mmol) of the compound (22) was obtained in the form of a free amine. 400 mg (0.61 mmol) of this free amine product was dissolved in a solvent mixture comprising 20 ml of ethyl acetate and 6 ml of chloroform and stirred. When 100 μ1 of conc. hydrochloric acid was added, a white precipitate was rapidly formed. Then 6 ml of methanol was added and the mixture was heated to approximately 70° C. to give a homogeneous solution. After allowing to cooling to room temperature, 380 mg (0.549 mmol) of the compound (22) thus precipitated was collected by filtering having a yield of 90% and a liquid crystal phase transition point of 135° C. SYNTHETIC EXAMPLE 10: SYNTHESIS OF COMPOUND (14) The same condensation and deprotection procedures as those described in Synthetic Example 1 were performed except that the 1,2-o-ditetradecyl-syn-glycerol was replaced with 1,2-o-dipalmitoyl-syn-glycerol. Thus the compound (14) was obtained having a liquid crystal phase transition point of 85° C. SYNTHETIC EXAMPLE 11: SYNTHESIS OF COMPOUND (6) Commercially available GlyGly was converted into Z-GlyGly in accordance with a known method, described, e.g., in "Peptide Gosei no Kiso to Jikken," ed. by Izumiya et al., (Maruzen). The same condensation procedure as the one described in Synthetic Example 1 was performed, except that the tBoc-GlyGly was replaced with Z-GlyGly. Thus the compound (6) was obtained in a Z-protected form. 2.93 g (4 mmol) of this protected product as compound (6) was dissolved in a solvent mixture comprising 20 ml of methanol, 20 ml of ethyl acetate and 430 μ1 of concentrated hydrochloric acid. After adding 400 mg of 5% palladium carbon, the mixture was hydrogenated at room temperature under atmospheric pressure for 2 hours. As the reaction proceeded, a white precipitate was formed. After the completion of the reaction, the crystals thus precipitated were dissolved by heating and then the catalyst was filtered off. The solvent was distilled off from the filtrate under reduced pressure and the residue was recrystallized from ethyl acetate. Thus 2.23 g (3.4 mmol) of the compound (6) was obtained having a yield of 58% and a liquid crystal phase transition point of 91° C. SYNTHETIC EXAMPLE 12: SYNTHESIS OF COMPOUND (12) The same condensation and deprotection procedures as those described in Synthetic Example 11 were performed except that the 1,2-o-ditetradecyl-syn-glycerol was replaced with 1,2-o-dimyristoyl-syn-glycerol. Thus the compound (12) was obtained having a liquid crystal phase transition point of 95° C. SYNTHETIC EXAMPLE 13: SYNTHESIS OF COMPOUND (14) The same condensation and deprotection procedures as those described in Synthetic Example 11 were performed except that the 1,2-o-ditetradecyl-syn-glycerol was replaced with 1,2-o-dipalmitoyl-syn-glycerol. Thus the compound (14) was obtained having a liquid crystal phase transition point of 100° C. SYNTHETIC EXAMPLE 14: SYNTHESIS OF COMPOUND (31) 710 mg (2.4 mmol) of tBoc-Ser(Bzl), 1 g (2.06 mmol) of 1,2-o-ditetradecyl-syn-glycerol and 24 mg of N,N-dimethylaminopyridine were dissolved in 15 ml of methylene chloride. To the obtained solution was added 460 mg of DCC under ice and stirring. Then the mixture was stirred under ice for 2 hours and at room temperature overnight. The dicyclohexyl urea thus precipitated was filtered and the solvent was distilled off from the filtrate under reduced pressure. To the residue, were added ethyl acetate and a 4% aqueous solution of sodium carbonate followed by extracting and separating. The organic phase was successively washed with a 10% aqueous solution of citric acid, water and saline and dried over sodium sulfate. After distilling off the ethyl acetate under reduced pressure, ##STR28## product. To the residue, were added 10 ml of methylene chloride and 5 ml of trifluoroacetic acid and the mixture was stirred at room temperature for 30 minutes. After distilling off the solvent under reduced pressure, ethyl acetate and a 4% aqueous solution of sodium carbonate were added to the residue followed by extracting and separating. The organic phase was successively washed with water and saline and dried over sodium sulfate. After distilling off the ethyl acetate under reduced pressure, ##STR29## product. To the residue, were added 710 mg of Z-Ser(tBoc), 310 mg of 1-hydroxynbenztriazole monohydrate, 10 ml of methylene chloride and 5 ml of DMF. The obtained solution was stirred under ice After adding 460 ml of DCC, the mixture was stirred under ice for 2 hours and at room temperature overnight. After treating in the same manner, the residue was purified by silica gel column chromatography (n-hexane/ethyl acetate=3/1). Thus 1.63 g (1.66 mmol) of ##STR30## was obtained having a yield of 80.5% (3 steps). 1.53 g (1.56 mmol) of this protected product was treated with trifluoroacetic acid in the same manner as the one described in Synthetic Example 1 to thereby remove the tBoc protecting group. Then the product was hydrogenated in the presence of hydrochloric acid in the same manner as the one described in Synthetic Example 11 to remove the benzyl-protecting group. Finally, the obtained compound (31) was recrystallized from a solvent mixture comprising ethyl acetate and methanol (10/1). Thus 770 mg (1.11 mmol) of the compound (31) was obtained having a yield of 71% (2 steps) and a liquid crystal phase transition point of 85° C. SYNTHETIC EXAMPLE 15: SYNTHESIS OF COMPOUND (5) The compound (5) was synthesized through the following pathway. ##STR31## SYNTHESIS OF COMPOUND (5a) 30 ml of a pyridine solution containing 7.3 g (15 mmol) of 1,2-o-ditetradecyl-syn-glycerol and 190 mg of N,N-dimethylaminopyridine was stirred under ice-cooling and 3 g (15.6 mmol) of p-toluenesulfonyl chloride was added thereto. After stirring at room temperature overnight, the reaction mixture was added to 40 ml of conc. hydrochloric acid diluted with 200 ml of water. The white precipitate thus formed was extracted and separated. Next, the organic phase was successively washed with water and saline and dried over sodium sulfate. After distilling off the ethyl acetate under reduced pressure, the residue was recrystallized from acetonirile. Thus 8.1 g (12.7 mmol) of the compound (5a) was obtained having a yield of 85%. SYNTHESIS OF COMPOUND (5b) 5.12 g (8 mmol) of the compound (5a) and 2.78 g (15 mmol) of phthalimide potassium were dissolved in 30 ml of DMF and stirred at 120° C. for 1 hour. After cooling to room temperature, 100 ml of ethyl acetate was added thereto and the insoluble matters were filtered off. The filtrate was successively washed with a 4% aqueous solution of sodium carbonate, water and saline and then dried over sodium sulfate. After distilling off the ethyl acetate under reduced pressure, the residue was purified by silica gel column chromatography (n-hexane/ethyl acetate =15/1). Thus 4.5 g (7.3 mmol) of the compound (5b) was obtained having a yield of 91%. SYNTHESIS OF COMPOUND (5c) 30 ml of an ethanol solution containing 4.3 g (7 mmol) of the compound (5b) and 0.7 g (14 mmol) of hydrazine monohydrate was stirred under reflux for 2 hours. After cooling by allowing to stand, 1.7 ml of conc. hydrochloric acid was added thereto. Then the ethanol was distilled off under reduced pressure and 50 ml of ethyl acetate and 50 ml of water were added to the residue followed by extracting and separating. The ethyl acetate phase was washed with a 1 N aqueous solution of sodium hydroxide and 2.2 g (10 mmol) of di-t-butyl dicarbonate was added thereto. After stirring at room temperature for 2 hours, the ethyl acetate solution was successively washed with a 4% aqueous solution of sodium hydrogencarbonate and saline. After concentrating the ethyl acetate under reduced pressure, the residue was purified by silica gel column chromatography (n-hexane/ethyl acetate=5/1). Thus 2.42 g (4.1 mmol) of the compound (5c) was obta as an amorphous product having a yield of 59%. FIG. 1 shows the 1 H NMR spectrum (20 mHz) of this compound in heavy chloroform. SYNTHESIS OF COMPOUND (5) 1.88 g (3.2 mmol) of the compound (5c) was dissolved in 20 ml of methylene chloride. After adding 10 ml of trifluoroacetic acid, the mixture was stirred at room temperature for 1 hour. After distilling off the solvent under reduced pressure, ethyl acetate was added to the residue followed by successively washing with a 1 N aqueous solution of sodium hydroxide and saline. Then it was dried over magnesium sulfate and the ethyl acetate was distilled off under reduced pressure. Thus 1.47 g (3.04 mmol) of the compound (5d) was obtained as a waxy product having a yield of 95%. This compound showed 484 (M + +H) in FAB-MS. The compound (5d) was employed in the following reaction without purifying. 1.37 g (2.83 mmol) of the compound (5d), 0.74 g (3.2 mmol) of tBoc-GlyGly and 0.49 g (3.2 mmol) of hydroxylbenztriazole monohydrate were dissolved in a solvent mixture of 15 ml of methylene chloride and 15 ml of DMF. Then 0.66 g of DCC was added thereto under cooling with water and the mixture was stirred overnight. The dicyclohexyl urea thus formed was filtered and the methylene chloride was distilled off under reduced pressure. Ethyl acetate was added to the residue followed by successively washing with a 4% aqueous solution of sodium carbonate and a 10% aqueous solution of citric acid. After distilling off the ethyl acetate under reduced pressure, the residue was purified by silica gel column chromatography (ethyl acetate/n-hexane =8/1). Thus 1.74 g (2.49 mmol) of the compound (5) was obtained in a tBoc-protected form having a yield of 82%. 1.66 g of this protected product was dissolved in 16 ml of methylene chloride. After adding 8 ml of trifluoroacetic acid, the mixture was stirred at room temperature for 30 minutes. Then the solvent was distilled off under reduced pressure and the residue was recrystallized from ethyl acetate. Thus 1.1 g (1.54 mmol) of the compound (5) was obtained having a yield of 65% and a liquid crystal phase transition point of 96° C. Liposomes comprising the compound (I) of the present invention may be prepared by known methods. That is to say, the liposome of the present invention may be prepared by any known methods without restriction, for example, a vortexing method [A.D. Bangham, J. Mol. Biol., 13, 238 (1965),] a sonication method [C. Huang. Biochem., 8, 344 (1969),] a prevesicle method [H. Trauble, Neurosci. Res. Prog. Bull., 9, 273 (1971),] an ethanol-injection method [S. Batzri, Biochem. Biophys. Acta., 298, 1015 (1973),] a French press extraction method [Y. Barenhollz, FEBS. Lett., 99, 210 (1979),] a cholic acid removal method [Y. Kagawa, J. Biol. Chem., 246, 5477 (1971),] a Triton X-100 batch method [W. J. Gerritsen, Eur. J. Biochem., 85, 255 (1978),] a Ca 2+ fusion method [D. PaPahadjopoulos, Biochem. Biophys. Acta., 394, 483 (1975),] an ether injection method [D. Deamer, Biochem. Biophys. Acta., 443, 629 (1976),] an annealing method [R. Lawaczeck, Biochem. Biophys. Acta., 443, 313 (1976),] a freeze-melt fusion method [M. Kasahara, J. Biol. Chem., 252, 7384 (1977).] a W/O/W emulsion method [S. Matsumoto, J. Colloid Interface Sci., 62, 149 (1977),] a reverse-phase evaporation method (F. Szoka, Proc. Natl. Acad. Sci. USA, 75, 4194 (1978),] a high-pressure emulsifying method [E. Mayhew, Biochem. Biophys. Acta., 775, 169 (1984)] as well as those described in JP-A-60-7932, JP-A-60-7933, JP-A-60-7934, JP-A-60-12127 and JP-A-62-152531. The substance to be encapsulated in the present invention may be either a hydrophilic drug or a lipophilic one. Furthermore, both of these drugs may be encapsulated simultaneously. Examples of hydrophilic drugs include anticancer agents such as adriamycin, actinomycin, mitomycin, 1β-arabinofurasylcytosine, bleomycin and cisplatin, antiviral agents such as interferon, aminoglycosides such as gentamycin, antibiotics such as β-lactam compounds (for example, sulbenicillin, cefoiam, and cefmenoxine), peptide hormones such as TRH and insulin, enzymes such as lysozyme, asparaginase and glycoxidase, immunopotentiators such as muramyl dipeptide and muramyl tripeptide and proteins such as immunoglobulin and various toxins. Examples of the lipophilic drug include anticancer agents such as ansamytocin, immunopotentiators such as TMD-66 [Gann 74 (2), 192-195 (1983)] and MTP-PE (JP-A-59-163389) and phospholipid derivatives (JP-A-59-163389). In addition, substances other than drugs (for example, marker, plasmid, DNA, RNA) may be used in the present invention without restriction, so long as they are useful when administered to living organisms. As the solution to be encapsulated, an aqueous solution prepared by dissolving an appropriate water-soluble substance in water may be used. In some cases, a solution prepared by simply dissolving a drug in water may be used. Examples of the water-soluble substances include known buffers (for example, phosphate buffer, citrate buffer), various salts (for example, sodium chloride, monosodium phosphate, disodium phosphate), saccharides (for example, glucose) and amino acids (for example, 1-arginine). Either one of these substances or a mixture thereof may be used. The solution to be encapsulated may further contain a preservative (for example, paraben), if required. The unencapsulated drug may easily be separated from liposomes by, for example, by known methods such as dialysis, filtration such as ultrafiltration or centrifugation. In this case, it is preferable to approximate the osmotic pressure of the internal aqueous phase to that of the external one as close as possible. Either one of the compounds of the present invention or a mixture thereof may be used. Further, other liposome film-forming lipids may be used together. Various phospholipids, sphingolipids or synthetic lipids may be used therefore. In order to further strengthen the film structure, various methods known in the art of phospholipid liposomes may be employed together. Typical examples of these methods include those comprising mixing sterol or cholesterol or coating with a polysaccharide polymer (JP-A-61-69801). Compounds of the present invention can form stable liposomes, though the radius of hydration of the hydrophilic moiety thereof is not so large as those of conventional bilayer film-forming lipids. This could be achieved by the intermolecular hydrogen bonds in the peptide region. When the compound of the present invention of the general formula (I) forms a monolayer at a gas/liquid interface, the oligopeptide region of the compound forms a completely stretched conformation and thus forms a hydrogen bond together with the adjacent peptide bond so as to cause a two-dimensional orientation. This interaction contributes to the formation of a highly dense film having a small molecular volume, compared with a phospholipid having the same hydrophobic chain. Films of the present invention, which have a domain formed by the oriented oligopeptide, can efficiently incorporate proteins such as enzymes, antigens, antibodies and receptors. Examples of such enzymes include oxidation-reduction enzymes such as glucose oxidase, amino acid oxidase, catalase, ascorbate oxidase, xanthine oxidase, cholesterol oxidase, glycerol oxidase, glcyerol-3-phosphate oxidase, choline oxidase, acetyl CoA oxidase, aldehyde oxidase, galactose oxidase, sarcosine oxidase, pyruvate oxidase, lactate oxidase, tyrosinase, and peroxidase; dehydrogenases such as alcohol dehydrogenase, glycerol dehydrogenase, glutamate dehydrogenase, lactate dehydrogenase, malate dehydrogenase, formaldehyde dehydrogenase, 3-a-hydroxysteroid dehydrogenase and cholesterol dehydrogenase; transferases such as creatine kinase, pyruvate kinase, hexokinase, glycerol kinase, myokinase and fructokinase; hydrolases such as urease, uricase, asparaginase, amylase, lipase, phospholipase, phosphatase, lactase, arginase, urokinase, esterase, trypsin, chymotrypsin, pectinase and penicillinase; isomerases such as citrate lyase, decarboxylase, fumarase, aspartase and glucose phosphate isomerase; and lygases such as glutathione synthetase and pyruvate synthetase. Examples of antigens and antibodies that can be used with films of the present invention include, a number of substances including serum albumin, syphilitic antibody, chorionic gonadotropin, and a α-fetoprotein. These substances are classified and described in "Meneki no Kenkyu" [ed. by Y. Yamamura, Kobun Shoin (1986),] the contents of which are incorporated by reference. In addition, biofunctional substances such as hemeproteins (for example, hemoglobin, cytochrome C) and metal complexes including porphyrin derivatives such as chlorophyrin can also be used with films of the present invention. Furthermore, water-soluble proteins such as albumin can be used. Examples of solvents for developing monolayer films to be used in the present invention include common volatile nonpolar organic solvents such as chloroform, dichloromethane, benzene, toluene and ether as well as mixtures thereof, together with polar hydrophilic solvents such as alcohols and water. Examples of subphases for preparing monolayers of the present invention include buffer solutions of various pH values and solutions of various metal salts such as calcium, barium, cadmium, potassium and sodium salts. The temperature of the subphase may be appropriately controlled according to known procedures, if required. The subphase may be fluidized by, for example, stirring or vibrated to thereby facilitate the reaction between the molecule for forming the monolayer and the compounds contained in the subphase. In the preparation of the monolayer film, the atmosphere on the subphase may be replaced with an inert gas such as N 2 or Ar to thereby prevent the monolayer from oxidation or deterioration. The monolayer thus formed on the water surface may be built up onto the surface of a base or a substrate by various known laminating methods including the aforesaid L-B technique. The L-B technique, which is a vertical build-up method, is described in, for example, J. A. Chem. Soc., 57, 1007 (1935); G. L. Gains Jr., "Insoluble Monolayers at Liquid-Gas Interfaces," Interscience, New York (1966); and K. Fukuda, "Zairyo Gijutsu", 4, 261 (1986). In addition to the L-B technique, various build-up methods including vertical build-up method and rotational build-up method (refer to, for example, JP-A-60-189929, JP-A-61-42394) may be employed. Multilayers may be obtained by repeatedly building up a monolayer on a substrate. A continuous lamination method described in, for example, JP-A-60-209245 may be used therefore. In this case, it is preferable that at least some portion of the host compound of the present invention is contained in the most external molecular layer. Molecular layers located close to the substrate, compared with the aforesaid layer, may consist of other organic amphiphatic compounds (surfactant-type molecules). The substrate (base) to be used in the formation of a monolayer or multilayers by the L-B technique in the present invention may be selected from among electrical conductors such as various metals, inorganic insulating materials such as vitreous inorganic materials (for example, glass, quartz), various organic and inorganic crystals, inorganic semiconductors (for example, SnO 2 , In 2 O 3 , ZnO, TiO 2 , WO 3 , GaAs, Si), organic semiconductors, organic conductors, organic polymers and composite materials consisting the above-mentioned ones. This material may be an electrode connected to an external electrical circuit or other sensors (for example, field effect mode transducer). The surface of the material may be physically or chemically treated by various methods so as to make hydrophilic or hydrophobic. An example of a hydrophobic treatment comprises reacting the surface of the substrate with an alkylsilane derivative which is employed as a coupling agent. In the structure of film materials of the present invention, the surface of the substrate or base may be chemically bound to molecules constituting the multilayers in contact therewith. Such bonds may be formed through a thermal chemical reaction between a reactive group (for example, hydroxyl group) on the surface of the substrate and the terminal reactive group (for example, active silane) of the molecule constituting the multilayers. The compound of the general formula (I) to be used in the present invention may be mixed with a film-forming compound, which is a reactive compound useful in binding a functional guest compound, for example, those described in JP-A-63-171642, JP-A-1-4246 and JP-A-1-56783. The present invention, wherein an arbitrary functional compound (for example, enzyme, protein) may be fixed on the surface of an ultra-thin film and then a highly efficient chemical reaction (for example, catalytic reaction, photochemical response, oxidation/reduction) or a physical change (for example, optical change, electrical change) shown by the functional compound can be monitored, and is available and known in various fields including the formation of sensor image, information recording and energy conversion, and thus is highly useful. To further illustrate the present invention, and not by way of limitation, the following Examples of liposomes and films according to the present invention will be given. EXAMPLE 1 30 mg of the compound (22) was dissolved in 10 ml of chloroform. After distilling off the chloroform with a rotary evaporator, the residue was further dried in vacuo to thereby form a film of the compound (22). 3 ml of a tris buffer solution (6 mM, pH 7.0) containing 150 mM of sodium chloride was added thereto followed by performing Vortex dispersion. After performing ultrasonic irradiation of bath-type at 50° C. for 10 minutes, the dispersion was heated to 80° C. for 10 minutes. Then it was filtered 6 times with the use of an extruder (0.2 μ polycarbonate filter, 55° C.) under elevated pressure (about 11 kg/cm 2 ). When the particle size was measured with a NICOMP, a single dispersion mode particle size distribution (average 149 nm) was obtained. Then the dispersion was stained with phosphotungstic acid and observed with a TEM. Thus it was confirmed that the vesicle consisted of a singly layer. EXAMPLE 2 A vortex dispersion obtained by the same method as the one described in Example 1 was subjected to ultrasonic irradiation of probe type (30 W, 5 minutes). Then it was confirmed, in the same manner as the one described in Example 1, that a monolayer vesicle of an average particle size of approximately 80 nm was formed. EXAMPLE 3 The gel/liquid crystal transition point of a compound of the present invention in pure water was measured with a Privalov type DSC. Table 1 shows the results. TABLE 1______________________________________Compound Transition point (°C.)______________________________________ 5 50 6 59 (59)16 53 (57)20 4821 6122 5723 4928 47______________________________________ Figures given in parentheses show data determined in a tris buffer solution (6 mM, pH 7.0). EXAMPLE 4 By using 30 mg of the compound (6), a film was formed in the same manner as the one described in Example 1. Next, 3 ml of a tris buffer solution (6 mM, pH 7.0) containing 50 mM of safranine-O and 200 mM of glucose was added thereto. Then it was subjected to Vortex-dispersing and ultrasonic treatment (bath-type), heated to 80° C. and then treated with an extruder, similar to the procedure of Example 1. The dispersion was subjected to gel-filtration by using Sephadex G-50 equilibrated with a tris buffer solution containing 150 mM of sodium chloride. Thus the unencapsulted safranine-O was separated. The lipid fraction (average particle size 140 nm) thus obtained was incubated at 37° C. and the leaking safranine-O was determined by fluorometry. For comparison, the above procedure was repeated except that the compound 6 was replaced with dipalmitoylphosphatidylcholine (DPPC) to thereby give liposomes (average particle size 60 nm) containing safranine-O. These liposomes were also incubated at 37° C. and the leaking safranine-O was determined. FIG. 2 shows the results. As FIG. 2 shows, the liposomes comprising the compound (6) of the present invention as a film component is superior to the ones comprising DPPC, which is a natural phospholipid, in barrier function on safranine-O. EXAMPLE 5 Liposomes containing safranine-O were prepared in the same manner as the one described in Example 4, except that the compound (6) was replaced with the compounds (8), (11), (14) and (22). Then the leakage of the safranine-O at 37° C. was examined. Table 2 shows the leakage ratios of the safranine-O after 1 hour. TABLE 2______________________________________Lipid Leakage ratio (%)______________________________________ 6 30 8 4111 5114 3722 46DPPC 44______________________________________ As Table 2 shows, the compounds of the present invention are comparable or superior to DPPC, which is a natural phospholipid, in barrier function. EXAMPLE 6 The procedure of Example 4 was repeated except that the compound (6) was replaced with the compound (16) to thereby give liposomes containing safranine-O. These liposomes were incubated at 4° C. Liposomes containing safranine-O prepared by using DPPC showed the formation of a precipitation when stored at 4° C. for 20 days. On the other hand, those prepared by using the compound (16) maintained a stable dispersion state after 4 months. After 80 days, these liposomes showed a leakage ratio of the safranine-O of as low as 6%. EXAMPLE 7 The procedure of Example 4 was repeated except that 20, 33 and 50% by mol of cholesterol was added to the compound (6). Thus liposomes containing safranine-O were prepared. These liposomes were incubated at 37° C. and the leaking safranine-O was determined by fluorometry. FIG. 3 shows the results. As FIG. 3 shows, the barrier function of the liposome comprising the compound of the present invention can be remarkably elevated by adding cholesterol. Further, it was confirmed by using a Privalov type DSC that the gel/liquid crystal transition point of the compound (6) disappeared when 50% of cholesterol was added. EXAMPLE 8 90 mg of the compound (16) was added to 9 ml of a tris buffer solution (6 mM, pH 7.0) containing 270 mM of glucose and then the mixture was dispersed for 1 minute thrice with the use of a homogenizer (8000 rpm). The obtained dispersion was heated to 50° C. for 10 minutes and then to 80° C. for 10 minutes, followed by performing ultrasonic irradiation of bath type at 55° C. for 10 minutes. After heating to 80° C. for 10 minutes again, the dispersion was filtered six times with the use of an extruder (0.1μpolycarbonate filter, 59° C.) under elevated pressure (approximately 15 kg/cm 2 ). The filtrate was gel-filtered through Sephadex G-50 (tris buffer solution, 6 mM, pH 7.0) to thereby separate the unencapsulated glucose. The average particle size of the lipid associate fraction thus obtained was 90 nm. Further, the fraction was negative-stained with phosphotungstic acid and then observed under an electron microscope. Thus it was confirmed that monolayer vesicles were formed. This fraction was incubated at 37° C. for 60 minutes and then ultracenytrifuged at 20° C. at 25,000 rpm for 30 minutes. When the glucose concentration of the supernatant was examined by enzymatic colorimetry, it was found out that the leakage ratio of glucose was 2%. (Triton X was added to the gel-filtered fraction to thereby break the vesicles. Then the glucose concentration thus determined by colorimetry was referred to as 100%.) EXAMPLE 9 The FTIR spectrum of the compound (22) was determined under the following conditions. (1) KBr pellet. (2) 10 mM chloroform solution. (3) Vesicles prepared in heavy water. Table 3 shows the absorption of the carbonyl stretch vibration of the amide. TABLE 3______________________________________Condition VC = 0 (cm.sup.-1)______________________________________(1) 1643(2) 1673(3) 1657______________________________________ Table 3 suggests the presence of a hydrogen bond between amido bonds which seemingly contributes to the formation of stable vesicles by the compound of the present invention. Now, the production of a film comprising the compound (I) of the present invention will be described. EXAMPLE 10 The compound (6) was dissolved in a solvent mixture of chloroform and methanol (4 : 1 v/v) to thereby give a 10 -3 M solution. Then the obtained solution was developed on a 10 -3 M tris buffer solution (pH 7.0) to thereby form a single dispersion film. The monolayer formed on the surface of water was slowly compressed with a belt-drive system barrier at 25° C. and thus the surface pressure/molecular occupation area (π-A) properties were determined. As a result, the curve shown in FIG. 4 was obtained. For comparison, the π-A properties of di-o-hexadecyl-syn-phosphatidylcholine (DHPC) were determined under the same conditions. FIG. 5 shows the result. The comparison of these Figs. indicate that the compound of the present invention formed a highly dense and thick monolayer which gives a π-A curve having a smaller molecular occupation area compared with the natural phospholipid having a hydrophobic moiety of the same structure (compound (6): 42 Å, DHPC: 55 Å) and showing a sharp rise-fall. EXAMPLE 11 FIGS. 6, 7, 8 and 9 show respectively the π-A curves of the compounds (22), (16), (12) and (31) each formed in the same manner as the one of Example 10. These Figs. indicate that each of these compounds has similar characteristics as those of the compound (6) of Example 10. EXAMPLE 12 A 1 mM solution of the compound (22) was developed on pure water and compressed to 30 dyn/cm. After controlling the surface pressure constantly, the film was transported onto a silicone substrate 20 times by the vertical immersion method. After sufficiently drying spontaneously, FT-IR was measured from the vertical direction to the surface of the substrate. As a result, the carbonyl absorption of the amido was 1663 cm -1 . The amido absorption of the compound (22) in a dilute chloroform solution in the absence of any hydrogen bond was 1673 cm -1 . Therefore a shift toward the low wave length by 10 cm -1 was observed in the state of multilayers. This shift might be caused by an intermolecular hydrogen bond between the adjacent oligopeptide. While the invention has been described in detailed with reference to specific embodiments, it will be apparent to one skilled in the art that various changes and modifications can be made to the invention without departing from its spirit and scope.

A peptide derivative amphiphatic compound or N-terminal salt thereof represented by formula (I): ##STR1## wherein R 1 and R 2 each represents a straight-chain or branched alkyl or acyl group having 8 to 24 carbon atoms optionally having a substituent or an unsaturated group; X represents --O--or --NH--; R 3n and R 3 (n+1) each represents an α--amino acid side chain; n is an integer of from 0 to 5; the compound may be a racemic compound or an optically active compound when the compound has an asymmetric carbon atom; and the N-terminal salt of the compound optionally forms with an acid component; an intermediate thereof, a liposome comprising said peptide derivative amphiphatic compound and a film consisting of a monolayer or multilayers comprising the peptide derivative amphiphatic compound are disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application Ser. No. 61/825,615, filed on May 21, 2013, and entitled “Methods And Systems For Quantitative Fluorescence-Based Detection Of Molecules And Proteins,” the entire disclosure of which is incorporated herein by reference. BACKGROUND 1. Field of Invention The present invention relates to methods and systems for the identification of biological threats, and, more particularly, to a novel fluorescence-based assay for the detection of molecules and proteins. 2. Background of Art There is a continued need for innovative approaches for the identification of biological threats, including Staphylococcal enterotoxin B (SEB), among many others. SEB is a protein produced by the bacterium Staphylococcus aureus that acts as a potent enterotoxin. While SEB is the toxin most commonly associated with food poisoning, it is also classified as a potential biological weapon as it is very stable, easily aerosolized, and causes great harm and incapacitation (including death) upon inhalation. The harmful effects of SEB are due to its ability to induce a massive and nonspecific activation of the immune system causing a toxic shock due to the high concentrations of cytokines released into the body. SEB, considered a superantigen, is toxic because of its ability to bind to and crosslink/activate immune cells. Therefore, SEB toxicity is not due to any inherent enzymatic activity. Specifically, the toxicity of SEB is associated with two defined binding sites located on the surface of the SEB protein itself; one binding site for the T-cell receptor (TCR) and the other for the major histocompatibility complex (MHC) class II. Existing assays available for SEB detection are based on Enzyme Linked Immunosorbent Assays (“ELISA”) technology. Quantitative forms of these ELISA-based detection assays are complex, time consuming and more suited for laboratory analysis. Fieldable versions of the ELISA-based assays, commonly referred to as hand-held assays (“HHA”), are not quantitative and have limited sensitivity. Additionally, all these assays are only capable of detecting the presence of SEB, without giving any indication of toxin activity/toxicity. Accordingly, there is a continued need for methods and systems that quickly and effectively identify the biological toxin and provide quantitative information about the toxin activity/toxicity. BRIEF SUMMARY In accordance with the foregoing objects and advantages, methods and systems are provided for detecting molecules and proteins, such as biological toxins, and providing quantitative information pertaining to molecule/protein concentration and/or toxin activity/toxicity. According to an embodiment is provided a quantitative one-step “activity” assay that can be performed inside or outside of a laboratory environment, and which can determine the threat level of an exposure or attack, including but not limited to the detection and activity of Staphylococcal enterotoxin B (“SEB”). The assay, which can be called the Proximity Activated PCR Assay (“PAPA”), for example, is a novel and simple-to-use detection assay that can identify and quantify any molecule or protein. This new technology incorporates the detection specificity of antibody binding with an initiation step that requires reverse transcriptase Polymerase Chain Reaction (“PCR”) and precise oligonucleotide interactions that are dependent on proximity/distance to activate a quantitative fluorescence-based PCR signal amplification reaction. According to an embodiment, the assay can be quickly run on any fluorescence-based PCR amplification platform in the lab or field. According to one embodiment, the PAPA overcomes the complexities associated with developing an assay to detect and identify SEB toxin activity. SEB toxicity is a consequential result of binding events that over-excite the immune system, and not associated with a specific product produced. To detect SEB activity, there was a need to utilize a molecular binding-based assay for detection. The crucial cross-linking binding sites on SEB for the TCR and MHC class II molecule have been mapped and therefore the toxic activity of an SEB molecule can be determined by verifying the presence of the TCR and MHC class II binding sites on the SEB molecule. To detect the toxic potential of a single SEB molecule, the PAPA requires dual antibody binding event utilizing available monoclonal antibodies that bind to the epitopes of the TCR and MHC class II binding sites. Any mutation in either of these binding sites, which would prevent dual antibody binding, would also make the SEB molecule non-toxic; as it would be unable to cross-link the TCR and the MHC class II molecule on cells within the immune system. Therefore, utilizing two distinct antibody clones that bind to different sites on the same molecule is an important component of the PAPA design. While a dual antibody binding event on an SEB molecule can determine its toxicity, it was also necessary to determine a way to associate a successful dual antibody binding event to the generation of measureable signal. One technology that utilizes antibody binding to a molecule in order to generate a signal are ELISAs. Sandwich ELISAs utilize two antibodies to the same molecule; one to capture the molecule to an assay plate and the other to bind to the “captured” molecules in order to detect and quantify the amount of molecule present. This detection typically utilizes enzymes that react with chromogenic reporter substrates to produce a change in color that is used as a signal. While ELISAs produce useful information, they are time consuming (5 to 6 hours), require multiple wash and incubation steps, and are typically designed for lab based experimentation. Therefore, ELISA based technology would not satisfy the requirement of a quantitative assay that must be simple and easy to perform outside of a lab environment. Another commonly used method of detecting a dual antibody binding event is Förster/fluorescence resonance energy transfer (“FRET”) technology. In typical FRET assays, different chromophores are attached to each antibody. When these antibodies come in close proximity to each other, energy is transferred from one chromophore to the other chromophore. The output of FRET can either be a gain of a fluorescence signal (if two appropriate chromophores are utilized) or a loss in fluorescence signal (if a chromophore and a “quencher” are utilized). Unfortunately, antibody based FRET technology would not be useful in a system for detecting SEB since the signal produced from FRET is typically weak and requires either a high degree of amplification or a situation where many FRET based interaction are occurring in order to be measurable and quantitative. Additionally, the use of antibodies would require multiple incubation and wash steps (3-4 hours) as non-specific FRET interactions may occur if the two antibodies come in close contact within the solution. Consequently, a simple FRET based assay would not work for a quantitative assay that must be simple and easy to perform outside of a lab environment. Accordingly, in one aspect, a method for detection of a target in a sample, the method comprising the steps of: providing an assay mixture comprising: (i) a first probe comprising a first antibody recognizing a first epitope of the target, the first antibody conjugated to an RNA oligonucleotide; (ii) a second probe comprising a second antibody recognizing a second epitope of the target, the second antibody conjugated to a DNA oligonucleotide; (iii) a reverse primer, wherein the reverse primer comprises a first region complimentary to the RNA oligonucleotide, and a second region complimentary to the DNA oligonucleotide; and (iv) a reverse transcriptase, wherein the reverse transcriptase creates a DNA transcription product from the RNA oligonucleotide using the reverse primer only if the RNA oligonucleotide and the DNA oligonucleotide are in close proximity; adding the sample to the assay mixture to create a reaction mixture; incubating the reaction mixture for a predetermined period of time under conditions suitable for reverse transcription by the reverse transcriptase; and analyzing the reaction mixture for the presence of the DNA transcription product of the RNA oligonucleotide; wherein when the target is present in the sample, and the first antibody is interacting with the first epitope, and the second antibody is interacting with the second epitope, the first region of the reverse primer binds the RNA oligonucleotide and the second region of the reverse primer binds the DNA oligonucleotide to bring the RNA oligonucleotide and the DNA oligonucleotide in close proximity; and wherein the presence of the DNA transcription product indicates the presence of the target in the sample. In some embodiments, the first antibody is conjugated to the 5′ end of the RNA oligonucleotide. In some embodiments, the second antibody is conjugated to the 3′ end of the DNA oligonucleotide. In some embodiments, the first region of the reverse primer is complimentary to the 3′ end of the RNA oligonucleotide. In some embodiments, the first region of the reverse primer comprises up to approximately eight nucleotides. In some embodiments, the second region of the reverse primer is complimentary to the 5′ end of the DNA oligonucleotide. In some embodiments, the assay mixture further comprises: (i) a DNA polymerase; (ii) a forward primer complimentary to at least a portion of the DNA transcription product and (iii) a detection probe comprising an oligonucleotide complimentary to at least a portion of the DNA transcription product, and further comprising a fluorophore at one end of the oligonucleotide and a quencher at the opposite end of the oligonucleotide; and further comprising the steps of: inactivating the reverse transcriptase; and incubating the reaction mixture for a predetermined period of time under conditions suitable for qPCR. In some embodiments, the method includes the step of incubating the sample with an antibody prior to the step of adding the sample to the assay mixture. In some embodiments, the assay mixture further comprises a modified DNA oligonucleotide complimentary to at least a portion of the RNA oligonucleotide. In some embodiments, the modification is selected from the group consisting of a 3′ spacer, a 3′ chain terminator, a 3′ fluorochrome, and combinations thereof. In some embodiments, the assay mixture further comprises a detection probe comprising an oligonucleotide complimentary to at least a portion of the RNA oligonucleotide. In one aspect, a method for detection of a target in a sample, the method comprising the steps of; providing an assay mixture comprising: (i) a first probe comprising a first antibody recognizing a first epitope of the target, the first antibody conjugated to the 5′ end of an RNA oligonucleotide; (ii) a second probe comprising a second antibody recognizing a second epitope of the target, the second antibody conjugated to the 3′ end of a DNA oligonucleotide; (iii) a reverse primer, wherein the reverse primer comprises a first region complimentary to 3′ end of the RNA oligonucleotide, and a second region complimentary to the 5′ end of the DNA oligonucleotide; (iv) a reverse transcriptase, wherein the reverse transcriptase creates a DNA transcription product from the RNA oligonucleotide using the reverse primer only if the RNA oligonucleotide and the DNA oligonucleotide are in close proximity; (v) a DNA polymerase; (vi) a forward primer complimentary to at least a portion of a DNA transcription product; and (vii) a detection probe comprising an oligonucleotide complimentary to at least a portion of the DNA transcription product, and further comprising a fluorophore at one end of the oligonucleotide and a quencher at the opposite end of the oligonucleotide; adding the sample to the assay mixture to create a reaction mixture; incubating the reaction mixture for a predetermined period of time under conditions suitable for reverse transcription by the reverse transcriptase; inactivating the reverse transcriptase; and incubating the reaction mixture for a predetermined period of time under conditions suitable for qPCR; wherein when the target is present in the sample, and the first antibody is interacting with the first epitope, and the second antibody is interacting with the second epitope, the first region of the reverse primer binds the RNA oligonucleotide and the second region of the reverse primer binds the DNA oligonucleotide to bring the RNA oligonucleotide and the DNA oligonucleotide in close proximity. In some embodiments, the method includes the step of analyzing the reaction mixture for the presence of the DNA transcription product of the RNA oligonucleotide, wherein the presence of the DNA transcription product indicates the presence of the target in the sample. In some embodiments, the method includes the step of analyzing the reaction mixture for fluorescence from the detection probe, wherein the presence of fluorescence from the detection probe indicates the presence of the target in the sample. In one aspect, a kit for detection of a target in a sample, including: an as say mixture comprising: (i) a first probe comprising a first antibody recognizing a first epitope of the target, the first antibody conjugated to an RNA oligonucleotide; (ii) a second probe comprising a second antibody recognizing a second epitope of the target, the second antibody conjugated to a DNA oligonucleotide; (iii) a reverse primer, wherein the reverse primer comprises a first region complimentary to the RNA oligonucleotide, and a second region complimentary to the DNA oligonucleotide; and (iv) a reverse transcriptase. In some embodiments, one or more components of the assay mixture are stored separately from the remainder of the components prior to use of the assay mixture. In some embodiments, the assay mixture further comprises: (i) a DNA polymerase; (ii) a forward primer complimentary to at least a portion of the DNA transcription product and (iii) a detection probe comprising an oligonucleotide complimentary to at least a portion of the DNA transcription product, and further comprising a fluorophore at one end of the oligonucleotide and a quencher at the opposite end of the oligonucleotide. In some embodiments, the first antibody is conjugated to the 5′ end of the RNA oligonucleotide. In some embodiments, the second antibody is conjugated to the 3′ end of the DNA oligonucleotide. In some embodiments, the first region of the reverse primer is complimentary to the 3′ end of the RNA oligonucleotide. In some embodiments, the first region of the reverse primer comprises up to approximately eight nucleotides. In some embodiments, the second region of the reverse primer is complimentary to the 5′ end of the DNA oligonucleotide. In some embodiments, the assay mixture further comprises a modified DNA oligonucleotide complimentary to at least a portion of the RNA oligonucleotide. In some embodiments, the modification is selected from the group consisting of a 3′ spacer, a 3′ chain terminator, a 3′ fluorochrome, and combinations thereof. In some embodiments, the assay mixture further comprises a detection probe comprising an oligonucleotide complimentary to at least a portion of the RNA oligonucleotide. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be more fully understood and appreciated by reading the following Detailed Description in conjunction with the accompanying drawings, in which: FIG. 1 is a diagrammatic representation of the assay components of the fluorescence-based assay in accordance with an embodiment; FIG. 2 is a diagrammatic representation of antibodies (conjugated with an oligonucleotide) binding to molecular target in accordance with an embodiment; FIG. 3 is a diagrammatic representation of a primer simultaneously binding to a short segment on the RNA-Left Arm element and a short segment on the DNA-Right arm element, which occurs when the two elements are brought together in close proximity after antibodies bind to molecular target, in accordance with an embodiment; FIG. 4 is a diagrammatic representation of reverse transcriptase synthesizing a single stranded DNA molecule from the RNA-Left Arm template, according to an embodiment; FIG. 5 is a diagrammatic representation of a first cycle of qPCR reaction, in which DNA polymerase synthesizes DNA from the reverse-transcribed DNA template and excises fluorophore from a probe, in accordance with an embodiment; FIG. 6 is a diagrammatic representation of a second cycle of qPCR reaction, in accordance with an embodiment; FIG. 7 is a graph of a qPCR reaction in accordance with an embodiment including variations of the Reverse Primers (with differing degrees of nucleotide overlap, from 0 to 8 bp, with the RNA-Left Arm) and preparations of the Left and Right Arms not conjugated to antibodies; FIG. 8 is a graph of a qPCR reaction analyzing the use of PAPA to detect insulin in accordance with an embodiment; FIG. 9 is a graph of a qPCR reaction analyzing the use of PAPA to detect IL-2 in accordance with an embodiment; FIG. 10A is a graph of a qPCR reaction analyzing the use of PAPA to detect active SEB toxin compared to inactive SEB toxoid in accordance with an embodiment; FIG. 10B is a graph of a qPCR reaction analyzing the use of PAPA and control isotype antibodies to detect active SEB toxin or inactive SEB toxoid in accordance with an embodiment; and FIG. 11 is a graph of a qPCR reaction analyzing the use of PAPA with CAPs and COMP Probe (to reduce background) to detect insulin in accordance with an embodiment. DETAILED DESCRIPTION In contrast to ELISA and FRET, PAPA—a new type of Oligonucleotide Linked Immunosorbent Assay (“OLISA”)—is capable of detecting a dual antibody binding event by producing a strong signal while avoiding multiple wash and incubation steps. See, for example, FIGS. 1 through 6 . According to an embodiment, the assay consists of two distinct antibody clones (Antibody-1 denoted by numeral 10 and Antibody-2 denoted by numeral 20 ) that recognize two different epitopes on the same molecule (See FIG. 1 ). Each of the antibody clones are conjugated or “linked” to oligonucleotides of a specified sequence and type. Antibody-1 is conjugated to an RNA oligonucleotide at its 5′ end, referred to as the RNA-left arm 30 . Antibody-2 is conjugated to a DNA oligonucleotide at its 3′ end, referred to as the DNA-right arm 40 . Also included in the assay mix is a DNA reverse primer 50 that is complimentary to the 5′ end of the DNA right arm, with the exception of the 3′ end of the DNA reverse primer that possesses a 1 to 8 (the number is dependent on the assay conditions) complimentary nucleotide bases to the 3′ end of the RNA-left arm (See FIGS. 1-3 ). According to one embodiment, the number of overlapping complimentary bases at the 3′ end of the DNA reverse primer which joins the RNA-left arm to the DNA-right arm is a critical element of the assay. Since so few nucleotide bases are involved in this interaction, the energy required to break this bond between the RNA-left arm to the DNA-right arm held together by the DNA reverse primer is minimal, and therefore would not normally occur in solution/suspension. However, when the RNA-left arm and DNA-right arm are brought into close proximity to each other, such as when bound together on the same molecule (See FIG. 2 ), the interaction becomes much more favorable. Therefore, when held in close proximity, the RNA-left arm and DNA-right arm can be held together with the DNA reverse primer (See FIG. 3 ). According to an embodiment, a reverse transcriptase 60 such as M-MLV, or a hot-start reverse transcriptase, among others, is used for the detection of the dual antibody binding event (See FIG. 1 ). This reverse transcriptase uses the DNA reverse primer and the RNA-left arm to create a DNA single stranded complimentary copy 70 of the RNA-left arm sequence (See FIG. 4 ). This DNA copy is only created when the RNA-left arm and DNA-right arm are joined together by the DNA reverse primer (with a minimized overlap to the RNA-left arm which cannot initiate the reaction in solutions lacking the target molecule), and thus the DNA copy is only created when Antibody-1 and Antibody-2 are joined together on the same molecule (See FIG. 4 ). Both the antibody binding and reverse transcriptase steps would occur at or near body temperature (including, but not limited to 37° C. to 42° C.), depending on the assay conditions. According to an embodiment, the reverse transcriptase step will only be allowed to occur for one cycle, and therefore the number of reverse-transcribed DNA copies made will be dependent on the number of molecules present onto which both Antibody-1 and Antibody-2 can bind. This makes the PAPA a quantitative assay. According to an embodiment, other components are utilized in the assay mix in order to quantify the number of reverse-transcribed DNA copies via a quantitative fluorescence PCR method. For example, these components could include a DNA polymerase 80 with 5′ exo-nuclease activity, a DNA forward primer 90 complimentary to the 3′ end of the reverse-transcribed DNA, and a DNA probe 100 with a fluorophore and a quencher at opposite ends that is complimentary to the reverse-transcribed DNA (See FIG. 1 ). To perform quantitative PCR, the temperature is initially raised to 95° C. At this temperature, the DNA polymerase 80 , such as a Hot-start DNA polymerase, is activated and non-heat stable proteins, such as the Reverse Transcriptase 60 and Antibody-1 and Antibody-2 are inactivated. Due to the inactivation of the reverse transcriptase and antibodies, no new reverse-transcribed DNA copies can be made. After this step, normal qPCR protocols can be followed. Temperatures are sequentially changed from the annealing (50-65° C.), to the elongation (55-72° C.), to the denaturation (95° C.) phases for each PCR cycle. During every cycle, a fluorescent signal is generated due to the separation of the fluorophore and quencher on a probe that is bound to a DNA template being transcribed by the DNA polymerase with 5′exo-nuclease activity (See FIGS. 5-6 ). The fluorescence signals increase throughout the PCR cycles until the signal exceeds a threshold, called the threshold cycle (“Ct”). The threshold cycle, or the cycle at which the fluorescence threshold is reached, is relative to the amount of starting material/Reverse-transcribed DNA copies/target molecules. Therefore, the PAPA is as quantifiable as a qPCR assay. In addition to the Ct value, the maximum fluorescence output of the assay can be used to quantify the amount of starting material/reverse-transcribed DNA copies/target molecules in the assay. According to an embodiment, other components can be added to the assay to reduce background signals within the PAPA. One such set of components, for example, would prevent the non-specific binding of DNA oligonucleotides to the RNA oligonucleotides. This can be accomplished by utilizing modified DNA oligonucleotides that possess a complimentary sequence to that of the RNA oligonucleotide. The modification on the DNA oligonucleotide would prevent the DNA nucleotide from being extended (i.e. used as a primer) by the DNA or RNA polymerase (reverse transcriptase). This modified DNA oligonucleotide is referred to as a “CAP”. The CAP can be of any length, as long as it maintains the ability to bind to the RNA oligonucleotide. Examples of modifications that prevent the CAP from being utilized as a primer include but are not limited to 3′ spacers (such as C3 spacer), 3′ chain terminators (such as dideoxcytidine or dideoxyguanine), and 3′ fluorochromes (such as fluorescein). In addition to CAPs, a qPCR probe can also be used to prevent the non-specific binding of DNA oligonucleotides to the RNA oligonucleotide if this probe was designed to be complimentary to a section. This type of blocking qPCR probe is referred to as a “COMP Probe”. According to an embodiment, in order to design a PAPA specific for the detection of unique molecules a few details should be considered. If possible, it should be determined where the two different antibodies bind to on the specified molecule. It is important to determine the orientation of one antibody to the other in order to correctly establish the antibody that should be conjugated with the RNA-left arm vs. the DNA-right arm. If not, a series of experiments may be performed to establish the correct orientation. Another consideration is the distance between the antibody binding sites on the specified molecule. Distance is a factor in that the RNA-left arm needs to be close enough to the DNA-right arm to allow for an overlap to occur. This distance can be compensated for by varying the length of the DNA-right arm (at its 3′end) as long as the complementary sequence for the DNA reverse primer is not affected. Another important factor to consider is minimizing the possibility of “heterodimer” interactions from the various sequences with the Left-RNA template. These interactions have the potential to cause “false-positive” signals (i.e. a positive signal in the absence of a dual-antibody binding event) if the RNA template is primed with a heterodimer sequence (a nucleotide sequence that is not associated with the 3-prime end of the reverse primer) that binds near the 3-prime end of the RNA template. The strength of these non-ideal interactions will be affected by the assay conditions and can be determined through experimental testing. According to yet another embodiment, there may be an initial antibody block step, such as with an isotype antibody, prior to the addition of the PAPA reagents. An additional wash step may or may not be included. According to an embodiment, all the components for the PAPA can be added at once without the need for buffer changes, washes, or incubation steps, which sets it apart from many other assays. Similar OLISA technologies, such as the Proximity Ligation Assay (“PLA”) and the exonuclease enabled Proximity Extension Assay (“PEA”) require multiple wash and incubation steps to produce the positive signals in their laboratory tests. Due to their time consuming and difficult set-up, these technologies are not suited for fieldable applications. Additionally, since fluorochromes are used for the detection signal, the PAPA has the potential to be multiplexed, where more than one molecule or protein can be detected per assay. Accordingly, the PAPA is a simple and easy to use one-step technology that can be designed to detect and quantify the presence of any molecule in a sample following analysis on any fluorescent PCR-based platform. According to one embodiment, in assays for SEB the SEB-PAPA is designed to detect and identify the toxic potential of SEB molecules found in unknown samples. Example 1 A methodological procedure for developing and testing a PAPA test using kanamycin resistance gene sequence. Although the kanamycin resistance gene sequence is utilized for the primers, templates, and probes in this version of the PAPA, use of this sequence is not mandatory. Other sequences, and other selective mechanisms, are possible. As an initial step, the development of the PAPA requires determination of the number of overlapping nucleotides between the reverse primer and RNA-Left Arm required to produce a positive signal in solution (i.e., without the requirement of being in close proximity caused by binding of the associated antibody to the target). This can be accomplished, for example, utilizing an assay comprising the reagents listed or described in FIG. 1 . According to one variation, the RNA-Left Arm and DNA-Right Arm will not be linked to or associated with an antibody. According to another variation, the RNA-Left Arm and DNA-Right Arm are linked to or associated with an antibody (including but not limited to the antibody that each element will be linked to in the final, field-deployed assay), but no target is introduced. Without target, the antibodies should not themselves cause the RNA-Left Arm and DNA-Right Arm elements to come into close proximity. According to an embodiment, nucleotide overlaps of 0, 1, 2, 3, 4, 5, 6, 7, and 8 can be utilized to promote the interaction between the RNA-Left Arm and the DNA-Right Arm. See, for example, the sequences listed in TABLE 1. Depending on the assay conditions (i.e. reaction temperature, annealing/elongation times, etc) and components (i.e. salts, enzyme concentration, contaminants, etc), the number of nucleotide overlaps required for the assay to produce a signal with and without a dual antibody binding event will vary. According to one embodiment, the assay can initially be tested in the context of simple qPCR and Reverse Transcriptase PCR, using conditions with a full RNA template or a shortened Left-RNA template (requiring a nucleotide overlap to produce a signal). According to yet another embodiment, the assay can be modified or made more specific by utilizing one or more oligonucleotide sequences with modified bases. For example, the assay can be designed to utilize oligonucleotides containing isoguanine (iso-dG) and 5′-methylisocytosine (iso-dC), which form specific bonds since iso-dG and iso-dC are unique and only form iso-dG/iso-dC or iso-dC/iso-dG bonds. Another example is the use of hybrid RNA/DNA oligonucleotide sequences. Many other examples of modified oligos are possible in order to increase or otherwise alter specificity in the assay. To determine the minimal degree of overlap required to produce a positive signal in a Reverse Transcriptase driven PCR reaction, an assay was set up using preparations of the Left-RNA Arm and Right-DNA Arm in which the “arms” were not conjugated to detection antibodies ( FIG. 2 ). The assay consisted of Forward Primer 2 (500 nM), Probe 2 (100 nM), RNA-Left Arm (not conjugated to an antibody; 1.2×10 7 molecules per reaction), DNA-Right Arm 5 (not conjugated to an antibody; 500 nM), Hot-start DNA polymerase (0.025 units per uL), Reverse Transcriptase (M-MLV; 1 unit per uL), DNA polymerase/Reverse Transcriptase buffer mix, and different versions of the Reverse Primers (with differing degrees of nucleotide overlap, from 0 to 8 bp, with the RNA-Left Arm; 500 nM). The reaction was performed with a 5 minute initial Reverse Transcriptase step at 37° C., followed by 94° C. hot start/denaturing step (4 minutes), and then 55 cycles of 94° C. (15 seconds) to 55° C. (30 seconds) in the Rotor-Gene Q qPCR instrument. Based on the results, when Reverse Primers with 6, 7 or 8 bp overlapping nucleotides are used, positive signals are generated in solution in the absence of antibody binding events ( FIG. 7 ). Additionally, no signals are generated when Reverse Primers with 0, 2, 3, 4 or 5 bp overlapping nucleotides are used ( FIG. 7 ). Therefore, antibody binding events would be required in these conditions to generate a signal when Reverse Primers with 2, 3, 4 or 5 bp overlapping nucleotides are used. TABLE 1 Oligonucleotides utilized for PAPA testing according to an embodiment. Oligonucleotide Oligonucleotide Sequence Name (5′ to 3′) Kan For 1 CGAGTGATTTTGATGACGAGCGT (SEQ ID NO: 1) Kan For 2 AGTGATTTTGATGACGAGCGTAA (SEQ ID NO: 2) Kan For 3 CGAGTGATTTTGATGACGA (SEQ ID NO: 3) Kan Right 1 ACCGGATTCAGTCGTCACTCATGGTGATTTC DNA Temp (SEQ ID NO: 4) Kan Right 2 ACCGGATTCAGTCGTCACTCATGGTGA DNA Temp (SEQ ID NO: 5) Kan Right 3 ACCGGATTCAGTCGTCACTCATGGT DNA Temp (SEQ ID NO: 6) Kan Right 4 ACCGGATTCAGTCGTCACTCATGGTGGT DNA Temp (SEQ ID NO: 7) Kan Right 5 ACCGGATTCAGTCGTCACTCATAATTAA DNA Temp (SEQ ID NO: 8) Kan Right 6 ACCGGATTCAGTCGTCACTCATCCATAA DNA Temp (SEQ ID NO: 9) Kan Right 7 ACCGGATTCAGTCGTCACTCATATATAA DNA Temp (SEQ ID NO: 10) Kan Rev 1-8 CGACTGAATCCGGTGAGAATGG overlap (SEQ ID NO: 11) Kan Rev 1-7  ACGACTGAATCCGGTGAGAATG overlap (SEQ ID NO: 12) Kan Rev 1-6 GACGACTGAATCCGGTGAGAAT overlap (SEQ ID NO: 13) Kan Rev 1-5 TGACGACTGAATCCGGTGAGAA overlap (SEQ ID NO: 14) Kan Rev 1-4 GTGACGACTGAATCCGGTGAGA overlap (SEQ ID NO: 15) Kan Rev 1-3 AGTGACGACTGAATCCGGTGAG overlap (SEQ ID NO: 16) Kan Rev 1-2 GAGTGACGACTGAATCCGGTGA overlap (SEQ ID NO: 17) Kan Rev 1-1 TGAGTGACGACTGAATCCGGTG overlap (SEQ ID NO: 18) Kan Rev 1-0 ATGAGTGACGACTGAATCCGGT overlap (SEQ ID NO: 19) Kan Probe 1 TGGCTGGCCTGTTGAACAAGTCTGGAAAGA (SEQ ID NO: 20) Kan Probe 2 CTGGCCTGTTGAACAAGTCTGGAAAGAAATG (SEQ ID NO: 21) Kan Probe 3 AATGGCTGGCCTGTTGAACAAGTCTGGA (SEQ ID NO: 22) Kan COMP TGGCTGGCCTGTTGAACAAGTCTGGAAAGA Probe 1 (SEQ ID NO: 23) Kan COMP CATTTCTTTCCAGACTTGTTCAACAGGCCAG Probe 2 (SEQ ID NO: 24 Kan COMP AATGGCTGGCCTGTTGAACAAGTCTGGA Probe 3 (SEQ ID NO: 25) CAP 24 GAGAATGGCAAAAGCTTATGCATT (SEQ ID NO: 26) CAP 20 GAGAATGGCAAAAGCTTATG (SEQ ID NO: 27) CAP 28 GAGAATGGCAAAAGCTTATGCATTTCTT (SEQ ID NO: 28) Kan Full CGAGUGAUUUUGAUGACGAGCGUAAUGGCUG RNA Temp GCCUGUUGAACAAGUCUGGAAAGAAAUGCAU AAGCUUUUGCCAUUCUCACCGGAUUCAGUCG UCACUCAU (SEQ ID NO: 29) Kan Left CGAGUGAUUUUGAUGACGAGCGUAAUGGCUG RNA Temp GCCUGUUGAACAAGUCUGGAAAGAAAUGCAU AAGCUUUUGCCAUUCUC (SEQ ID NO: 30) As a second step in PAPA testing, antibody binding studies utilizing antibodies conjugated to oligonucleotides can be performed to determine if close proximity can promote PCR. The experiment described above for the first step can be repeated, this time with the RNA-Left Arm and DNA-Right Arm elements conjugated to antibodies (preferably the antibodies that each element will be linked to in the final, field-deployed assay) and target will be introduced to the system. According to an embodiment (see Example 2), antibodies against human insulin from Mercodia (Mab 1 Anti-Insulin and Mab 2 Anti-Insulin) can be utilized, with human insulin (from Tocris) used as the target protein. These Mercodia anti-insulin antibodies have been reported to be successful in an antibody-based proximity ligation assay. According to another embodiment (see Example 3), antibodies against mouse interleukin-2 (IL-2) from eBioscience (JES6-1A12 and JES6-5H4) can be utilized, with recombinant mouse IL-2 (from eBioscience) as the target protein in the PAPA. These eBioscience anti-insulin antibodies have been utilized in mouse IL-2 ELISA assays. According to another embodiment (see Example 4), antibodies against SEB (2B33 and B87, both available from Santa Cruz Biotechnology) can be utilized with SEB toxin (from BEI resources) as the target protein in the PAPA. These antibodies target the SEB active (TCR and MHC class II) binding sites. The 2B33 antibody blocks MHC class II binding and the B87 antibody blocks TCR binding. According to yet another embodiment, any antibody, aptamer or substance/protein/molecule that can specifically (or non-specifically) bind to a target protein or molecule and be conjugated to an oligonucleotide can be utilized in the PAPA. According to an embodiment, initial studies use a RNA-Left Arm. Additionally, InnovaBiosciences will be utilized initially to conjugate the oligonucleotides to the antibodies. According to an embodiment, the antibodies and target are different from those described herein, and are instead another known or to-be-discovered antibody/antigen recognition pair. Example 2 Experiment to test whether the PAPA can be utilized to detect insulin. Antibodies against human insulin (Mab 1 Anti-Insulin and Mab 2 Anti-Insulin) were obtained from Mercodia and conjugated to RNA (Kan Left RNA Temp) and DNA (Kan Right 5 DNA Temp) oligonucleotides by InnovaBiosciences. These sequences were chosen based on data from supporting experiments. Initial conjugations utilized a 2:1 oligo:antibody ratio. Mab 1 Anti-Insulin antibody was conjugated to the RNA oligo, making it the Anti-Insulin Left-RNA Arm. Mab 2 Anti-Insulin antibody was conjugated to the DNA oligo, making it the Anti-Insulin Right-DNA Arm. The assay consisted of Kan Forward Primer 2 (500 nM), Kan Probe 2 (100 nM), Anti-Insulin Left-RNA Arm (1.6×10 10 molecules per reaction), Anti-Insulin Right-DNA Arm (1.6×10 10 molecules per reaction), Hot-start DNA polymerase (0.025 units per uL), Reverse Transcriptase (M-MLV; 1 unit per uL), RNasin (0.4 units per uL), DNA polymerase/Reverse Transcriptase buffer mix, Kan Reverse Primers 1-3 (500 nM) and varying amounts of Insulin (0.116 or 1.16 ng) or H20 (control). The reaction was performed with a 1 hour initial Reverse Transcriptase step at 37° C., followed by 94° C. hot start/denaturing step (4 minutes), and then 55 cycles of 94° C. (15 seconds) to 55° C. (30 seconds) in the Rotor-Gene Q qPCR instrument in a total volume of 15 uL per reaction. The results are shown in FIG. 8 . The Insulin PAPA is able to detect both concentrations of Insulin (0.116 and 1.16 ng) compared to the H20 samples, with lower Ct values and higher fluorescent outputs for the Insulin samples compared to the H20 samples. In addition, the highest concentrations of Insulin (1.16 ng) produced the lowest Ct values and highest fluorescent outputs, indicating that the assay results correlate to the amount of target added. Example 3 Experiment to test whether the PAPA can be utilized to detect IL-2. Antibodies against mouse IL-2 (JES6-1A12 and JES6-5H4) were obtained from eBioscience and conjugated to RNA (Kan Left RNA Temp) and DNA (Kan Right 5 DNA Temp) oligonucleotides by InnovaBiosciences. These sequences were chosen based on data from supporting experiments. Initial conjugations utilized a 2:1 oligo:antibody ratio. The JES6-1A12 Anti-IL-2 antibody was conjugated to the RNA oligo, making it the Anti-IL-2 Left-RNA Arm. The JES6-5H4 Anti-IL-2 antibody was conjugated to the DNA olgio, making it the Anti-IL-2 Right-DNA Arm. The assay consisted of Kan Forward Primer 2 (500 nM), Kan Probe 2 (100 nM), Anti-IL-2 Left-RNA Arm (1.6×10 10 molecules), Anti-IL-2 Right-DNA Arm (1.6×10 10 molecules per reaction), Hot-start DNA polymerase (0.025 units per uL), Reverse Transcriptase (M-MLV; 1 unit per uL), RNasin (0.4 units per uL), DNA polymerase/Reverse Transcriptase buffer mix, Kan Reverse Primers 1-3 (500 nM) and varying amounts of IL-2 (0.20 or 2.0 ng) or H20 (control). The reaction was performed with a 1 hour initial Reverse Transcriptase step at 37° C., followed by 94° C. hot start/denaturing step (4 minutes), and then 55 cycles of 94° C. (15 seconds) to 55° C. (30 seconds) in the Rotor-Gene Q qPCR instrument in a total volume of 15 uL per reaction. The results are shown in FIG. 9 . The IL-2 PAPA is able to detect both concentrations of IL-2 (0.20 and 2.0 ng) compared to the H20 samples, with lower Ct values and higher fluorescent outputs for the IL-2 samples compared to the H20 samples. In addition, the highest concentrations of IL-2 (2.0 ng) produced the lowest Ct values and highest fluorescent outputs, indicating that the assay results correlate to the amount of target added. Example 4 Experiment to test whether the PAPA can be utilized to detect active SEB toxin versus inactive SEB toxoid. Antibodies against SEB (2B33 and B87) or an isotype control (eBioscience, Rat IgG2a) were conjugated to RNA (Kan Left RNA Temp) and DNA (Kan Right DNA Temp) oligonucleotides by InnovaBiosciences. These sequences were chosen based on data from supporting experiments. Initial conjugations utilized a 2:1 oligo:antibody ratio. The 2B33 Anti-SEB antibody was conjugated to the RNA oligo, making it the Anti-SEB Left-RNA Arm. The B87 Anti-SEB antibody was conjugated to the DNA olgio, making it the Anti-SEB Right-DNA Arm. For a control, the isotype antibody was also conjugated to the RNA and DNA oligos, making a Control Left-RNA Arm and Control Right-DNA Arm, respectively. The SEB assay consisted of Kan Forward Primer 2 (500 nM), Kan Probe 2 (100 nM), Anti-SEB Left-RNA Arm (1.6×10 10 molecules per reaction), Anti-SEB Right-DNA Arm (1.6×10 10 molecules per reaction), Hot-start DNA polymerase (0.025 units per uL), Reverse Transcriptase (M-MLV; 1 unit per uL), RNasin (0.4 units per uL), DNA polymerase/Reverse Transcriptase buffer mix, Kan Reverse Primers 1-3 (500 nM) and added SEB toxin (BEI, 200 ng), inactivated SEB toxoid (BEI, 200 ng) or H20 (control). The control assay consisted of the same components above, with the Control Arms being used in place of the SEB Arms. The reaction was performed with a 5 minute initial Reverse Transcriptase step at 37° C., followed by 94° C. hot start/denaturing step (4 minutes), and then 55 cycles of 94° C. (15 seconds) to 55° C. (30 seconds) in the BioRad CFX96 qPCR instrument in a total volume of 15 uL per reaction. The results are shown in FIG. 10A and FIG. 10B . The SEB PAPA is able to detect the active SEB toxin samples compared to the H20 and inactive SEB toxoid samples, with lower Ct values and higher fluorescent outputs for the SEB toxin compared to the H20 and SEB toxoid samples ( FIG. 10A ). This indicates that the SEB PAPA is specific for active SEB toxin ( FIG. 10A ). The Control PAPA shows that there are no differences between SEB toxin samples compared to the H20 samples, with similar Ct values and fluorescent outputs, indicating that the SEB toxin is not detected in the Control PAPA ( FIG. 10B ). The SEB toxoid produces higher Ct values and lower fluorescent outputs, indicating that the SEB toxoid is also not detected in the Control PAPA ( FIG. 10B ). Example 5 Experiment to test whether the PAPA with CAPs and COMP Probe can be utilized to detect insulin. Antibodies against human insulin (Mab 1 Anti-Insulin and Mab 2 Anti-Insulin) were obtained from Mercodia and conjugated to RNA (Kan Left RNA Temp) and DNA (Kan Right 5 DNA Temp) oligonucleotides by InnovaBiosciences. These sequences were chosen based on data from supporting experiments. Initial conjugations utilized a 2:1 oligo:antibody ratio. Mab 1 Anti-Insulin antibody was conjugated to the RNA oligo, making it the Anti-Insulin Left-RNA Arm. Mab 2 Anti-Insulin antibody was conjugated to the DNA olgio, making it the Anti-Insulin Right-DNA Arm. The assay consisted of Kan Forward Primer 2 (500 nM), Kan COMP Probe 2 (100 nM), CAP 20 (1.3 uM), Anti-Insulin Left-RNA Arm (1.6×10 10 molecules per reaction), Anti-Insulin Right-DNA Arm (1.6×10 10 molecules per reaction), Hot-start DNA polymerase (0.025 units per uL), Reverse Transcriptase (M-MLV; 1 unit per uL), RNasin (0.4 units per uL), DNA polymerase/Reverse Transcriptase buffer mix, Kan Reverse Primers 1-3 (500 nM) and varying amounts of Insulin (0.116 or 1.16 ng) or H20 (control). The reaction was performed with a 1 hour initial Reverse Transcriptase step at 37° C., followed by 94° C. hot start/denaturing step (4 minutes), and then 55 cycles of 94° C. (15 seconds) to 55° C. (30 seconds) in the Rotor-Gene Q qPCR instrument in a total volume of 15 uL per reaction. The results are shown in FIG. 11 . The Insulin PAPA with CAPs and COMP Probe 2 is able to detect both concentrations of Insulin (0.116 and 1.16 ng) compared to the H20 samples, with lower Ct values and higher fluorescent outputs for the Insulin samples compared to the H20 samples. In addition, the highest concentrations of Insulin (1.16 ng) produced the lowest Ct values and highest fluorescent outputs, indicating that the assay results correlate to the amount of target added. Compared to the Insulin PAPA without CAPs and COMP Probe 2 ( FIG. 8 ), less background signal is produced when CAPs and COMP Probe 2 are present in the PAPA ( FIG. 11 ). While various embodiments have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the function and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the embodiments described herein. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the teachings is/are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, embodiments may be practiced otherwise than as specifically described and claimed. Embodiments of the present disclosure are directed to each individual feature, system, article, material, kit, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and/or methods, if such features, systems, articles, materials, kits, and/or methods are not mutually inconsistent, is included within the scope of the present disclosure.

A kit and method for detection of a target in a sample. An assay mixture provided in the kit and used in the method includes a first probe with a first antibody recognizing a first epitope of the target and conjugated to an RNA oligonucleotide; a second probe with a second antibody recognizing a second epitope of the target and conjugated to a DNA oligonucleotide; a reverse primer with a first region complimentary to the RNA oligonucleotide and a second region complimentary to the DNA oligonucleotide; and a reverse transcriptase that creates a DNA transcription product from the RNA oligonucleotide using the reverse primer only if the RNA oligonucleotide and the DNA oligonucleotide are in close proximity. If the target is present in the sample, the reverse primer binds the RNA oligonucleotide and the DNA oligonucleotide to bring the RNA oligonucleotide and the DNA oligonucleotide in close proximity.

[0001] This application is a continuation-in-part of PCT/GB2010/000968, filed 13 May 2010, which claims priority to U.S. Provisional Patent Application Ser. Nos. 61/181,386, filed on 27 May 2009, and 61/181,418, filed 27 May 2009, and United Kingdom Patent Application Nos. 0908245.4, filed on 13 May 2009 and 0908247.0, filed 13 May 2009, and is a continuation-in-part of PCT/GB2010/000958, filed 13 May 2010, which claims priority to U.S. Provisional Patent Application Ser. No. 61/181,415, filed 27 May 2009, and United Kingdom Patent Application No. 0908246.2, filed 13 May 2009, and is a continuation-in-part of PCT/GB2010/000964, filed 13 May 2010, which claims priority to U.S. Provisional Patent Application Ser. No. 61/181,418, filed 27 May 2009, and United Kingdom Patent Application No. 0908247.0, filed 13 May 2009, and is a continuation-in-part of PCT/GB2010/000966, filed 13 May 2010, which claims priority to U.S. Provisional Patent Application Ser. No. 61/181,428, filed 27 May 2009, and United Kingdom Patent Application No. 0908248.8, filed 13 May 2009. The entire contents of these applications are incorporated herein by reference. BACKGROUND [0002] Mass spectrometers comprising a gas chromatograph coupled to an Electron Ionisation (“EI”) or Chemical Ionisation (“CI”) ion source are well known. A gas chromatograph comprises a packed column or open capillary tube located in a heated chamber. Analyte gas molecules are caused to pass through the column. Gas molecules having different sizes and structures will take different amounts of time to elute from the gas chromatograph. [0003] Ions which emerge from the gas chromatograph are then commonly ionised either by an Electron Ionisation ion source or by a Chemical Ionisation ion source. [0004] An EI ion source comprises an ion chamber through which an electron beam is passed. Analyte gas molecules interact with the electron beam and are subsequently ionised. The ionisation process is commonly referred to as being a hard ionisation process in that the analyte molecules are caused to fragment as a result of the ionisation process. The resulting EI fragment ions are then mass analysed. [0005] A CI ion source utilises a reagent gas (e.g. methane or ammonia) and may be operated in either a positive or negative mode of operation. Neutral reagent gas is arranged to be ionised by interactions with free electrons emitted from a filament. The resulting reagent ions are then caused to interact and ionise neutral analyte molecules resulting in the formation of analyte ions. The resulting analyte ions are then mass analysed. [0006] The coupling of a gas chromatography column with an EI or CI ion source and a mass spectrometer is a powerful technique that is widely used in many laboratories. [0007] Conventionally, EI and CI ion sources comprise ion source chambers made from stainless steel. Stainless steel is considered to be relatively inert and non-reactive. However, conventional EI and CI ion source chambers need regular cleaning in order to maintain high performance. [0008] Conventional EI and CI ion source chambers can suffer from increased surface contamination following regular analysis of complex matrix extracts such as urine, saliva, plasma, whole blood, waters and soils. SUMMARY [0009] Some embodiments entail coated ion source components, in particular EI and CI ion sources, for example, with a coating at least on portions of one of the source volume, trap, repeller electrodes and ion exit plate, to optionally improve the sensitivity of a mass spectrometer. [0010] According to an aspect of some preferred embodiments, there is provided a mass spectrometer comprising an ion source, wherein the ion source comprises a first coating or surface provided on at least a portion of the ion source. [0011] The ion source preferably comprises one or more ionisation chambers and the first coating or surface is preferably provided on at least a portion of the one or more ionisation chambers. [0012] The ion source preferably further comprises one or more repeller electrodes and the first coating or surface is preferably provided on at least a portion of the one or more repeller electrodes. [0013] The ion source and/or the one or more ionisation chambers and/or the one or more repeller electrodes forming part of the ion source are preferably made from a material selected from the group consisting of: (i) stainless steel; (ii) a steel alloy comprising a 11.5% chromium wt. %; (iii) an austenitic stainless steel; (iv) a ferritic stainless steel; (v) an austenitic-ferritic or duplex steel; (vi) titanium; (vii) a titanium alloy; (viii) a nickel-base alloy; (ix) a nickel-chromium alloy; (x) a nickel-chromium alloy comprising ≧50.0% nickel wt. %; and (xi) INCONEL® 600, 625, 690, 702, 718, 939 or X750. [0014] The ion source and/or the one or more ionisation chambers and/or the one or more repeller electrodes forming part of the ion source preferably comprise stainless steel or an alloy comprising: (i) 0-0.01 wt. % carbon; (ii) 0.01-0.02 wt. % carbon; (iii) 0.02-0.03 wt. % carbon; (iv) 0.03-0.04 wt. % carbon; (v) 0.04-0.05 wt. % carbon; (vi) 0.05-0.06 wt. % carbon; (vii) 0.06-0.07 wt. % carbon; (viii) 0.07-0.08 wt. % carbon; and (ix)>0.08 wt. % carbon. [0015] The ion source and/or the one or more ionisation chambers and/or the one or more repeller electrodes forming part of the ion source preferably comprise stainless steel or an alloy comprising: (i) 0-0.01 wt. % nitrogen; (ii) 0.01-0.02 wt. % nitrogen; (iii) 0.02-0.03 wt. % nitrogen; (iv) 0.03-0.04 wt. % nitrogen; (v) 0.04-0.05 wt. % nitrogen; (vi) 0.05-0.06 wt. % nitrogen; (vii) 0.06-0.07 wt. % nitrogen; and (viii)>0.07 wt. % nitrogen. [0016] The ion source and/or the one or more ionisation chambers and/or the one or more repeller electrodes forming part of the ion source preferably comprise stainless steel or an alloy comprising: (i) 0-0.1 wt. % nitrogen; (ii) 0.1-0.2 wt. % nitrogen; (iii) 0.2-0.3 wt. % nitrogen: (iv) 0.3-0.4 wt. % nitrogen; (v) 0.4-0.5 wt. % nitrogen; (vi) 0.5-0.6 wt. % nitrogen; (vii) 0.6-0.7 wt. % nitrogen; and (viii)>0.7 wt. % nitrogen. [0017] The ion source and/or the one or more ionisation chambers and/or the one or more repeller electrodes forming part of the ion source preferably comprise stainless steel or an alloy comprising: (i) 12.0-13.0 wt. % chromium; (ii) 13.0-14.0 wt. % chromium; (iii) 14.0-15.0 wt. % chromium; (iv) 15.0-16.0 wt. % chromium; (v) 16.0-17.0 wt. % chromium; (vi) 17.0-18.0 wt. % chromium; (vii) 18.0-19.0 wt. % chromium; (viii) 19.0-20.0 wt. % chromium; (ix) 20.0-21.0 wt. % chromium; (x) 21.0-22.0 wt. % chromium; (xi) 22.0-23.0 wt. % chromium; (xii) 23.0-24.0 wt. % chromium; (xiii) 24.0-25.0 wt. % chromium; (xiv) 25.0-26.0 wt. % chromium; (xv) 26.0-27.0 wt. % chromium; (xvi) 27.0-28.0 wt. % chromium; (xvii) 28.0-29.0 wt. % chromium; (xviii) 29.0-30.0 wt. % chromium; and (xix)>30.0 wt. % chromium. [0018] The ion source and/or the one or more ionisation chambers and/or the one or more repeller electrodes forming part of the ion source preferably comprise stainless steel or an alloy comprising: (i) 0-1.0 wt. % nickel; (ii) 1.0-2.0 wt. % nickel; (iii) 2.0-3.0 wt. % nickel; (iv) 3.0-4.0 wt. % nickel; (v) 4.0-5.0 wt. % nickel; (vi) 5.0-6.0 wt. % nickel; (vii) 6.0-7.0 wt. % nickel; (viii) 7.0-8.0 wt. % nickel; (ix) 8.0-9.0 wt. % nickel; (x) 9.0-10.0 wt. % nickel; (xi) 10.0-11.0 wt. % nickel; (xii) 11.0-12.0 wt. % nickel; (xiii) 12.0-13.0 wt. % nickel; (xiv) 13.0-14.0 wt. % nickel; (xv) 14.0-15.0 wt. % nickel; (xvi) 15.0-16.0 wt. % nickel; (xvii) 16.0-17.0 wt. % nickel; (xviii) 17.0-18.0 wt. % nickel; (xix) 18.0-19.0 wt. % nickel; (xx) 19.0-20.0 wt. % nickel; (xxi) 20.0-21.0 wt. % nickel; (xxii) 21.0-22.0 wt. % nickel; (xxiii) 22.0-23.0 wt. % nickel; (xxiv) 23.0-24.0 wt. % nickel; (xxv) 24.0-25.0 wt. % nickel; (xxvi) 25.0-26.0 wt. % nickel; (xxvii) 26.0-27.0 wt. % nickel; (xxviii) 27.0-28.0 wt. % nickel; (xxix) 28.0-29.0 wt. % nickel; (xxx) 29.0-30.0 wt. % nickel; (xxxi) 30.0-31.0 wt. % nickel; (xxxii) 31.0-32.0 wt. % nickel; (xxviii) 32.0-33.0 wt. % nickel; (xxxiv) 33.0-34.0 wt. % nickel; (xxxv) 34.0-35.0 wt. % nickel; (xxxvi) 35.0-36.0 wt. % nickel; (xxxvii) 36.0-37.0 wt. % nickel; (xxxviii) 37.0-38.0 wt. % nickel; (xxxix) 38.0-39.0 wt. % nickel; (xl) 39.0-40.0 wt. % nickel; (xli) 40.0-41.0 wt. % nickel; (xlii) 41.0-42.0 wt. % nickel; (xliii) 42.0-43.0 wt. % nickel; (xliv) 43.0-44.0 wt. % nickel; (xlv) 44.0-45.0 wt. % nickel; (xlvi) 45.0-46.0 wt. % nickel; (xlvii)>46.0 wt. % nickel. [0019] The ion source and/or the one or more ionisation chambers and/or the one or more repeller electrodes forming part of the ion source preferably comprise stainless steel or an alloy comprising: (i) 0-1.0 wt. % molybdenum; (ii) 1.0-2.0 wt. % molybdenum; (iii) 2.0-3.0 wt. % molybdenum; (iv) 3.0-4.0 wt. % molybdenum; (v) 4.0-5.0 wt. % molybdenum; (vi) 5.0-6.0 wt. % molybdenum; (vii) 6.0-7.0 wt. % molybdenum; (viii) 7.0-8.0 wt. % molybdenum; and (ix)>8.0 wt. % molybdenum. [0020] The ion source and/or the one or more ionisation chambers and/or the one or more repeller electrodes forming part of the ion source preferably comprise stainless steel or an alloy comprising: (i) 0-1.0 wt. % copper; (ii) 1.0-2.0 wt. % copper; (iii) 2.0-3.0 wt. % copper; (iv) 3.0-4.0 wt. % copper; and (v)>4.0 wt. % copper. [0021] The ion source and/or the one or more ionisation chambers and/or the one or more repeller electrodes forming part of the ion source preferably comprise stainless steel or an alloy comprising: (i) 0.01-1.0 wt. % X; (ii) 1.0-2.0 wt. % X; (iii) 2.0-3.0 wt. % X; (iv) 3.0-4.0 wt. % X; and (v)>4.0 wt. % X; wherein X comprises cobalt and/or tantalum and/or aluminium and/or titanium and/or niobium and/or silicon and/or manganese and/or tungsten and/or phosphorous. [0022] The first coating or surface is preferably provided on: (i) at least 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 100% of an inner surface and/or an outer surface of the ion source; and/or (ii) at least 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 100% of an inner surface and/or an outer surface of the one or more ionisation chambers; and/or (iii) at least 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 100% of an inner surface and/or an outer surface of the one or more repeller electrodes. [0023] Some preferred coatings or layers include: 1) metallic carbide, such as TiC; 2) metallic boride; 3) ceramic or DLC, such as SIC; and 4) ion-implanted transition metals, such as ion-implanted titanium. For convenience, these four groups are summarized, in turn, next. [0024] 1) Metallic Carbide—The first coating or surface is preferably selected from the group consisting of: (i) aluminium carbide or Al 4 C 3 ; (ii) chromium carbide, CrC, Cr 23 C 6 , Cr 3 C, Cr 7 C 3 or Cr 3 C 2 ; (iii) copper carbide; (iv) hafnium carbide, HfC or HfC 0.99 ; (v) iron carbide, Fe 3 C, Fe 7 C 3 or Fe 2 C; (vi) iridium carbide; (vii) manganese carbide, MnC or Mn 23 C 6 ; (viii) molybdenum carbide, Mo 2 C or Mo 3 C 2 ; (ix) nickel carbide or NiC; (x) niobium carbide, NbC, Nb 2 C, NbC 0.99 , or Nb 4 C 3 ; (xi) osmium carbide; (xii) palladium carbide; (xiii) platinum carbide; (xiv) rhenium carbide; (xv) rhodium carbide or RhC; (xvi) ruthenium carbide; (xvii) scandium carbide or ScC; (xviii) tantalum carbide, TaC, Ta 2 C, TaC 0.99 or Ta 4 C 3 ; (xix) titanium carbide or TiC; (xx) tungsten carbide, WC or W 2 C; (xxi) vanadium carbide, VC, VC 0.97 , V 4 C 3 ; (xxii) yttrium carbide or YC 2 ; (xxiii) zirconium carbide, ZrC or ZrC 0.97 ; and (xxiv) silicon carbide or SiC. [0025] The first coating or surface preferably comprises: (i) a transition metal carbide; (ii) a carbide alloy; or (iii) a mixed metal carbide alloy. [0026] The first coating or surface preferably has either: [0027] (a) a resistivity selected from the group consisting of: (i) <10 3 Ω-m; (ii) <10 −4 Ω-m; (iii) <10 −5 Ω-m; (iv) <10 −6 Ω-m; (v) <10 −7 Ω-m; (vi) 10 −3 -10 −4 Ω-m; (vii) 10 −4 -10 −5 Ω-m; (viii) 10 −5 -10 −6 Ω-m; and (ix) 10 −6 -10 −7 Ω-m; and/or [0028] (b) a Vickers hardness number or Vickers Pyramid Number (HV) selected from the group consisting of: (i) >1000; (ii) 1000-1100; (iii) 1100-1200; (iv) 1200-1300; (v) 1300-1400; (vi) 1400-1500; (vii) 1500-1600; (viii) 1600-1700; (ix) 1700-1800; (x) 1800-1900; (xi) 1900-2000; (xii) 2000-2100; (xiii) 2100-2200; (xiv) 2200-2300; (xv) 2300-2400; (xvi) 2400-2500; (xvii) 2500-2600; (xviii) 2600-2700; (xix) 2700-2800; (xx) 2800-2900; (xxi) 2900-3000; (xxii) 3000-3100; (xxiii) 3100-3200; (xxiv) 3200-3300; (xv) 3300-3400; (xvi) 3400-3500; and (xvii) >3500, wherein the Vickers hardness number or Vickers Pyramid Number is determined at a load of 30, 40, 50, 60 or 70 kg; and/or [0029] (c) a Vickers microhardness selected from the group consisting of: (i) >1000 kg/mm; (ii) 1000-1100 kg/mm; (iii) 1100-1200 kg/mm; (iv) 1200-1300 kg/mm; (v) 1300-1400 kg/mm; (vi) 1400-1500 kg/mm; (vii) 1500-1600 kg/mm; (viii) 1600-1700 kg/mm; (ix) 1700-1800 kg/mm; (x) 1800-1900 kg/mm; (xi) 1900-2000 kg/mm; (xii) 2000-2100 kg/mm; (xiii) 2100-2200 kg/mm; (xiv) 2200-2300 kg/mm; (xv) 2300-2400 kg/mm; (xvi) 2400-2500 kg/mm; (xvii) 2500-2600 kg/mm; (xviii) 2600-2700 kg/mm; (xix) 2700-2800 kg/mm; (xx) 2800-2900 kg/mm; (xxi) 2900-3000 kg/mm; (xxii) 3000-3100 kg/mm; (xxiii) 3100-3200 kg/mm; (xxiv) 3200-3300 kg/mm; (xv) 3300-3400 kg/mm; (xvi) 3400-3500 kg/mm; and (xvii) >3500 kg/mm, and/or [0030] (d) a thickness selected from the group consisting of: (i)<1 μm; (ii) 1-2 μm; (iii) 2-3 μm; (iv) 3-4 μm; (v) 4-5 μm; (vi) 5-6 μm; (vii) 6-7 μm; (viii) 7-8 μm; (ix) 8-9 μm; (x) 9-10 μm; (xi) >10 μm; and/or [0031] (e) a density selected from the group consisting of: (i) <3.0 g cm 3 ; (ii) 3.0-3.5 g cm −3 ; (iii) g cm −3 ; (iv) 4.0-4.5 g cm −3 ; (v) 4.5-5.0 g cm −3 ; (vi) 5.0-5.5 g cm −3 ; (vii) 5.5-6.0 g cm −3 ; (viii) 6.0-6.5 g cm −3 ; (ix) 6.5-7.0 g cm −3 ; (x) 7.0-7.5 g cm −3 ; (xi) 7.5-8.0 g cm −3 ; (xii) 8.0-8.5 g cm −3 ; (xiii) 8.5-9.0 g cm −3 ; (xiv) 9.0-9.5 g cm −3 ; (xv) 9.5-10.0 g cm −3 ; (xvi) 10.0-10.5 g cm −3 ; (xvii) 10.5-11.0 g cm −3 ; (xviii) 11.0-11.5 g cm −3 ; (xix) 11.5-12.0 g cm −3 ; (xx) 12.0-12.5 g cm −3 ; (xxi) 12.5-13.0 g cm −3 ; (xxii) 13.0-13.5 g cm −3 ; (xxiii) 13.5-14.0 g cm −3 ; (xxiv) 14.0-14.5 g cm −3 ; (xxv) 14.5-15.0 g cm −3 ; (xxvi) 15.0-15.5 g cm −3 ; (xxvii) 15.5-16.0 g cm −3 ; (xxviii) 16.0-16.5 g cm −3 ; (xxix) 16.5-17.0 g cm −3 ; (xxx) 17.0-17.5 g cm −3 ; (xxxi) 17.5-18.0 g cm −3 ; (xxxii) 18.0-18.5 g cm −3 ; (xxxiii) 18.5-19.0 g cm −3 ; (xxxiv) 19.0-19.5 g cm −3 ; (xxxv) 19.5-20.0 g cm −3 ; and (xxxvi) >20.0 g cm −3 ; and/or [0032] (f) a coefficient of friction selected from the group consisting of: (i) <0.01; (ii) 0.01-0.02; (iii) 0.02-0.03; (iv) 0.03-0.04; (v) 0.04-0.05; (vi) 0.05-0.06; (vii) 0.06-0.07; (viii) 0.07-0.08; (ix) 0.08-0.09; (x) 0.09-0.10; and (xi) >0.1. [0033] The ion source is preferably selected from the group consisting of: (i) an Electrospray ionisation (“ESI”) ion source; (ii) an Atmospheric Pressure Photo Ionisation (“APPI”) ion source; (iii) an Atmospheric Pressure Chemical Ionisation (“APCI”) ion source; (iv) a Matrix Assisted Laser Desorption Ionisation (“MALDI”) ion source; (v) a Laser Desorption Ionisation (“LDI”) ion source; (vi) an Atmospheric Pressure Ionisation (“API”) ion source; (vii) a Desorption Ionisation on Silicon (“DIOS”) ion source; (viii) an Electron Impact (“EI”) ion source; (ix) a Chemical Ionisation (“CI”) ion source; (x) a Field Ionisation (“Fr”) ion source; (xi) a Field Desorption (“FD”) ion source; (xii) an Inductively Coupled Plasma (“ICP”) ion source; (xiii) a Fast Atom Bombardment (“FAB”) ion source; (xiv) a Liquid Secondary Ion Mass Spectrometry (“LSIMS”) ion source; (xv) a Desorption Electrospray Ionisation (“DESI”) ion source; (xvi) a Nickel-63 radioactive ion source; (xvii) an Atmospheric Pressure Matrix Assisted Laser Desorption Ionisation ion source; (xviii) a Thermospray ion source; (xix) an Atmospheric Sampling Glow Discharge Ionisation (“ASGDI”) ion source; and (xx) a Glow Discharge (“GD”) ion source. [0034] The portion of the ion source having the first coating or surface is preferably selected from the group consisting of: (i) an ion chamber; (ii) a repeller electrode; and (iii) an exit plate or exit aperture arranged at the exit of the ion source through which ions of interest are desired to be transmitted. [0035] According to an aspect of the present invention there is provided a method of mass spectrometry comprising: [0036] ionising ions in an ion source having a first coating or surface provided on at least a portion of the ion source, wherein the first coating or surface comprises a metallic carbide coating or surface. [0037] According to an aspect of the present invention there is provided a method of making an ion source and/or one or more ionisation chambers and/or one or more repeller electrodes forming part of an ion source for a mass spectrometer comprising: [0038] depositing, sputtering or forming a first coating or surface on at least a portion of an ion source and/or one or more ionisation chambers and/or one or more repeller electrodes forming part of the ion source, wherein the first coating or surface comprises a metallic carbide coating or surface. [0039] The step of depositing, sputtering or forming the first coating or surface preferably comprises using a method selected from the group consisting of: (i) magnetron sputtering; (ii) closed field unbalanced magnetron sputter ion plating; (iii) electroplating; (iv) thermal spray coating; (v) vapour deposition; (vi) Chemical Vapour Deposition (“CVD”); (vii) combustion torch/flame spraying; (viii) electric arc spraying; (ix) plasma spraying; (x) ion plating; (xi) ion implantation; (xii) sputtering; (xiii) sputter deposition; (xiv) laser surface alloying; (xv) Physical Vapour Deposition (“PVD”); (xvi) plasma-based ion plating; (xvii) gas plasma discharge sputtering; (xviii) laser cladding; (xix) plasma enhanced Chemical Vapour Deposition; (xx) low pressure Chemical Vapour Deposition; (xxi) laser enhanced Chemical Vapour Deposition; (xxii) active reactive evaporation; (xxiii) Pulsed Laser Deposition (“PLD”); (xxiv) RF-sputtering; (xxv) Ion-Beam Sputtering (“IBS”); (xxvi) reactive sputtering; (xxvii) Ion-Assisted Deposition (“IAD”); (xxviii) high target utilisation sputtering; (xxix) High Power Impulse Magnetron Sputtering (“HIPIMS”); and (xxx) DC-sputtering. [0040] Preferably, the first coating or surface is selected from the group consisting of: (i) aluminium carbide or Al 4 C 3 ; (ii) chromium carbide, CrC, Cr 23 C 6 , Cr 3 C, Cr 7 C 3 or Cr 3 C 2 ; (iii) copper carbide; (iv) hafnium carbide, HfC or HfC 0.99 ; (v) iron carbide, Fe 3 C, Fe 7 C 3 or Fe 2 C; (vi) iridium carbide; (vii) manganese carbide, MnC or Mn 23 C 6 ; (viii) molybdenum carbide, Mo 2 C or Mo 3 C 2 ; (ix) nickel carbide or NiC; (x) niobium carbide, NbC, Nb 2 C, NbC 0.99 , or Nb 4 C 3 ; (xi) osmium carbide; (xii) palladium carbide; (xiii) platinum carbide; (xiv) rhenium carbide; (xv) rhodium carbide or RhC; (xvi) ruthenium carbide; (xvii) scandium carbide or ScC; (xviii) tantalum carbide, TaC, Ta 2 C, TaC 0.99 or Ta 4 C 3 ; (xix) titanium carbide or TiC; (xx) tungsten carbide, WC or W 2 C; (xxi) vanadium carbide, VC, VC 0.97 , V 4 C 3 ; (xxii) yttrium carbide or YC 2 ; (xxiii) zirconium carbide, ZrC or ZrC 0.97 ; and (xxiv) silicon carbide or SiC. [0041] 2) Metallic Boride—The first coating or surface is preferably selected from the group consisting of: (i) aluminium diboride, aluminium dodecaboride, AIB 2 or AIB 12 ; (ii) chromium diboride or CrB 2 ; (iii) copper boride; (iv) hafnium diboride or HfB 2 ; (v) iridium boride; (vi) iron boride, FeB or Fe 2 B; (vii) manganese boride, manganese diboride, MnB or MnB 2 ; (viii) molybdenum diboride or MoB 2 ; (ix) nickel boride, NiB, Ni 2 B or Ni 3 B; (x) niobium diboride or NbB 2 ; (xi) osmium boride; (xii) palladium boride; (xiii) platinum boride; (xiv) rhenium boride; (xv) rhodium boride; (xvi) ruthenium boride; (xvii) scandium boride or ScB; (xviii) silicon hexaboride, silicon tetraboride, SiB 6 or SiB 4 ; (xix) tantalum diboride or TaB 2 ; (xx) titanium diboride or TiB 2 ; (xxi) tungsten diboride or WB 2 ; (xxii) vanadium diboride or VB 2 ; (xxiii) yttrium boride; and (xxiv) zirconium diboride or ZrB 2 . [0042] The first coating or surface preferably comprises: (i) a transition metal boride or diboride; (ii) a boride or diboride alloy; or (iii) a mixed metal boride or diboride alloy. [0043] The first coating or surface preferably has either: [0044] (a) a resistivity selected from the group consisting of: (i) <10 −3 Ω-m; (ii) <10 −4 Ω-m; (iii) <10 −5 Ω-m; (iv) <10 −6 Ω-m; (v) <10 −7 Ω-m; (vi) 10 −3 -10 −4 Ω-m; (vii) 10 −4 -10 −5 Ω-m; (viii) 10 −5 -10 −6 Ω-m; and (ix) 10 −6 -10 −7 Ω-m; and/or [0045] (b) a Vickers hardness number or Vickers Pyramid Number (HV) selected from the group consisting of: (i) >1000; (ii) 1000-1100; (iii) 1100-1200; (iv) 1200-1300; (v) 1300-1400; (vi) 1400-1500; (vii) 1500-1600; (viii) 1600-1700; (ix) 1700-1800; (x) 1800-1900; (xi) 1900-2000; (xii) 2000-2100; (xiii) 2100-2200; (xiv) 2200-2300; (xv) 2300-2400; (xvi) 2400-2500; (xvii) 2500-2600; (xviii) 2600-2700; (xix) 2700-2800; (xx) 2800-2900; (xxi) 2900-3000; (xxii) 3000-3100; (xxiii) 3100-3200; (xxiv) 3200-3300; (xv) 3300-3400; (xvi) 3400-3500; and (xvii) >3500, wherein the Vickers hardness number or Vickers Pyramid Number is determined at a load of 30, 40, 50, 60 or 70 kg; and/or [0046] (c) a Vickers microhardness selected from the group consisting of: (i) >1000 kg/mm; (ii) 1000-1100 kg/mm; (iii) 1100-1200 kg/mm; (iv) 1200-1300 kg/mm; (v) 1300-1400 kg/mm; (vi) 1400-1500 kg/mm; (vii) 1500-1600 kg/mm; (viii) 1600-1700 kg/mm: (ix) 1700-1800 kg/mm; (x) 1800-1900 kg/mm; (xi) 1900-2000 kg/mm; (xii) 2000-2100 kg/mm; (xiii) 2100-2200 kg/mm; (xiv) 2200-2300 kg/mm; (xv) 2300-2400 kg/mm; (xvi) 2400-2500 kg/mm; (xvii) 2500-2600 kg/mm; (xviii) 2600-2700 kg/mm; (xix) 2700-2800 kg/mm; (xx) 2800-2900 kg/mm; (xxi) 2900-3000 kg/mm; (xxii) 3000-3100 kg/mm; (xxiii) 3100-3200 kg/mm; (xxiv) 3200-3300 kg/mm; (xv) 3300-3400 kg/mm; (xvi) 3400-3500 kg/mm; and (xvii) >3500 kg/mm, and/or [0047] (d) a thickness selected from the group consisting of: (i) <1 μm; (ii) 1-2 μm; (iii) 2-3 μm; (iv) 3-4 μm; (v) 4-5 μm; (vi) 5-6 μm; (vii) 6-7 μm; (viii) 7-8 μm; (ix) 8-9 μm; (x) 9-10 μm; (xi) >10 μm; and/or [0048] (e) a density selected from the group consisting of: (i) <3.0 g cm −3 ; (ii) 3.0-3.5 g cm −3 ; (iii) 3.5-4.0 g cm −3 ; (iv) 4.0-4.5 g cm −3 ; (v) 4.5-5.0 g cm −3 ; (vi) 5.0-5.5 g cm −3 ; (vii) 5.5-6.0 g cm −3 ; (viii) 6.0-6.5 g cm −3 ; (ix) 6.5-7.0 g cm −3 ; (x) 7.0-7.5 g cm −3 ; (xi) 7.5-8.0 g cm −3 ; (xii) 8.0-8.5 g cm −3 ; (xiii) 8.5-9.0 g cm −3 ; (xiv) 9.0-9.5 g cm −3 ; (xv) 9.5-10.0 g cm −3 ; (xvi) 10.0-10.5 g cm −3 ; (xvii) 10.5-11.0 g cm −3 ; (xviii) 11.0-11.5 g cm −3 ; (xix) 11.5-12.0 g cm −3 ; (xx) 12.0-12.5 g cm −3 ; (xxi) 12.5-13.0 g cm −3 ; (xxii) 13.0-13.5 g cm −3 ; (xxiii) 13.5-14.0 g cm −3 ; (xxiv) 14.0-14.5 g cm −3 ; (xxv) 14.5-15.0 g cm −3 ; (xxvi) 15.0-15.5 g cm −3 ; (xxvii) 15.5-16.0 g cm −3 ; (xxviii) 16.0-16.5 g cm −3 ; (xxix) 16.5-17.0 g cm −3 ; (xxx) 17.0-17.5 g cm −3 ; (xxxi) 17.5-18.0 g cm −3 ; (xxxii) 18.0-18.5 g cm −3 ; (xxxiii) 18.5-19.0 g cm −3 ; (xxxiv) 19.0-19.5 g cm −3 ; (xxxv) 19.5-20.0 g cm −3 ; and (xxxvi) >20.0 g cm −3 ; and/or [0049] (f) a coefficient of friction selected from the group consisting of: (i) <0.01; (ii) 0.01-0.02; (iii) 0.02-0.03; (iv) 0.03-0.04; (v) 0.04-0.05; (vi) 0.05-0.06; (vii) 0.06-0.07; (viii) 0.07-0.08; (ix) 0.08-0.09; (x) 0.09-0.10; and (xi) >0.1. [0050] The portion of the ion source having the first coating or surface is preferably selected from the group consisting of: (i) an ion chamber; (ii) a repeller electrode; and (iii) an exit plate or exit aperture arranged at the exit of the ion source through which ions of interest are desired to be transmitted. [0051] The ion source is preferably selected from the group consisting of: (i) an Electrospray ionisation (“ESI”) ion source; (ii) an Atmospheric Pressure Photo Ionisation (“APPI”) ion source; (iii) an Atmospheric Pressure Chemical Ionisation (“APCI”) ion source; (iv) a Matrix Assisted Laser Desorption Ionisation (“MALDI”) ion source; (v) a Laser Desorption Ionisation (“LDI”) ion source; (vi) an Atmospheric Pressure Ionisation (“API”) ion source; (vii) a Desorption Ionisation on Silicon (“DIOS”) ion source; (viii) an Electron Impact (“EI”) ion source; (ix) a Chemical Ionisation (“CI”) ion source; (x) a Field Ionisation (“FI”) ion source; (xi) a Field Desorption (“FD”) ion source; (xii) an Inductively Coupled Plasma (“ICP”) ion source; (xiii) a Fast Atom Bombardment (“FAB”) ion source; (xiv) a, Liquid Secondary Ion Mass Spectrometry (“LSIMS”) ion source; (xv) a Desorption Electrospray Ionisation (“DESI”) ion source; (xvi) a Nickel-63 radioactive ion source; (xvii) an Atmospheric Pressure Matrix Assisted Laser Desorption Ionisation ion source; (xviii) a Thermospray ion source; (xix) an Atmospheric Sampling Glow Discharge Ionisation (“ASGDI”) ion source; and (xx) a Glow Discharge (“GD”) ion source. [0052] According to another aspect of the present invention there is provided a method of mass spectrometry comprising: [0053] ionising ions in an ion source having a first coating or surface provided on at least a portion of the ion source, wherein the first coating or surface comprises a metallic boride coating or surface. [0054] According to another aspect of the present invention there is provided a method of making an ion source and/or one or more ionisation chambers and/or one or more repeller electrodes forming part of an ion source for a mass spectrometer comprising: [0055] depositing, sputtering or forming a first coating or surface on at least a portion of an ion source and/or one or more ionisation chambers and/or one or more repeller electrodes forming part of the ion source, wherein the first coating or surface comprises a metallic boride coating or surface. [0056] The step of depositing, sputtering or forming the first coating or surface preferably comprises using a method selected from the group consisting of: (i) magnetron sputtering; (ii) closed field unbalanced magnetron sputter ion plating; (iii) electroplating; (iv) thermal spray coating; (v) vapour deposition; (vi) Chemical Vapour Deposition (“CVD”); (vii) combustion torch/flame spraying; (viii) electric arc spraying; (ix) plasma spraying; (x) ion plating; (xi) ion implantation; (xii) sputtering; (xiii) sputter deposition; (xiv) laser surface alloying; (xv) Physical Vapour Deposition (“PVD”); (xvi) plasma-based ion plating; (xvii) gas plasma discharge sputtering; (xviii) laser cladding; (xix) plasma enhanced Chemical Vapour Deposition; (xx) low pressure Chemical Vapour Deposition; (xxi) laser enhanced Chemical Vapour Deposition; (xxii) active reactive evaporation; (xxiii) Pulsed Laser Deposition (“PLD”); (xxiv) RF-sputtering; (xxv) Ion-Beam Sputtering (“IBS”); (xxvi) reactive sputtering; (xxvii) Ion-Assisted Deposition (“IAD”); (xxviii) high target utilisation sputtering: (xxix) High Power Impulse Magnetron Sputtering (“HIPIMS”); and (xxx) DC-sputtering. [0057] Preferably, the first coating or surface is selected from the group consisting of: (i) aluminium diboride, aluminium dodecaboride, AIB 2 or AIB 12 ; (ii) chromium diboride or CrB 2 ; (iii) copper boride; (iv) hafnium diboride or HfB 2 ; (v) iridium boride; (vi) iron boride, FeB or Fe 2 B; (vii) manganese boride, manganese diboride, MnB or MnB 2 ; (viii) molybdenum diboride or MoB 2 ; (ix) nickel boride, NIB, Ni 2 B or Ni 3 B; (x) niobium diboride or NbB 2 ; (xi) osmium boride; (xii) palladium boride; (xiii) platinum boride; (xiv) rhenium boride; (xv) rhodium boride; (xvi) ruthenium boride; (xvii) scandium boride or ScB; (xviii) silicon hexaboride, silicon tetraboride, SiB 5 or SiB 4 ; (xix) tantalum diboride or TaB 2 ; (xx) titanium diboride or TiB 2 ; (xxi) tungsten diboride or WB 2 ; (xxii) vanadium diboride or VB 2 ; (xxiii) yttrium boride; and (xxiv) zirconium diboride or ZrB 2 . [0058] 3) Ceramic, and DLC—A Diamond Like Carbon (“DLC”) coating is an amorphous carbon coating and differs therefore from diamond coatings which are polycrystalline. A DLC coating is conductive which is particularly advantageous compared with diamond coatings which are insulating and non-conductive. [0059] A DLC coating also has a low coefficient of friction and is therefore highly non-stick. DLC coatings are also particularly robust and have a high hardness and have a high temperature resistance. The DLC coating is therefore particularly advantageous compared with graphite which will tend to oxidise at high temperatures. [0060] The Diamond Like Carbon coating preferably comprises a SP2 (graphite) to SP3 (diamond) ratio selected from the group consisting of: (i) <0.1; (ii) 0.1-0.2; (iii) 0.2-0.3; (iv) 0.3-0.4; (v) 0.4-0.5; (vi) 0.5-0.6; (vii) 0.6-0.7; (viii) 0.7-0.8; (ix) 0.8-0.9; and (x) 0.9-1.0. [0061] The Diamond Like Carbon coating or surface preferably comprises a carbon coating or surface having a diamond-like structure. [0062] The Diamond Like Carbon coating or surface preferably further comprises a metal component such as chromium. [0063] The ceramic coating or surface preferably comprises silicon carbide or SiC. [0064] The first coating or surface preferably has either: [0065] (a) a resistivity selected from the group consisting of: (i) <10 −3 Ω-m; (ii) <10 −4 Ω-m; (iii) <10 −5 Ω-m; (iv) <10 −6 Ω-m; (v) <10 −7 Ω-m; (vi) 10 −3 -10 −4 Ω-m; (vii) 10 −4 -10 −5 Ω-m; (viii) 10 −5 -10 −6 Ω-m; and (ix) 10 −6 -10 −7 Ω-m; and/or [0066] (b) a Vickers hardness number or Vickers Pyramid Number (HV) selected from the group consisting of: (i) >1000; (ii) 1000-1100; (iii) 1100-1200; (iv) 1200-1300; (v) 1300-1400; (vi) 1400-1500; (vii) 1500-1600; (viii) 1600-1700; (ix) 1700-1800; (x) 1800-1900; (xi) 1900-2000; (xii) 2000-2100; (xiii) 2100-2200; (xiv) 2200-2300; (xv) 2300-2400; (xvi) 2400-2500; (xvii) 2500-2600; (xviii) 2600-2700; (xix) 2700-2800; (xx) 2800-2900; (xxi) 2900-3000; (xxii) 3000-3100; (xxiii) 3100-3200; (xxiv) 3200-3300; (xv) 3300-3400; (xvi) 3400-3500; and (xvii) >3500, wherein the Vickers hardness number or Vickers Pyramid Number is determined at a load of 30, 40, 50, 60 or 70 kg; and/or [0067] (c) a Vickers microhardness selected from the group consisting of: (i) >1000 kg/mm; (ii) 1000-1100 kg/mm; (iii) 1100-1200 kg/mm; (iv) 1200-1300 kg/mm; (v) 1300-1400 kg/mm; (vi) 1400-1500 kg/mm; (vii) 1500-1600 kg/mm; (viii) 1600-1700 kg/mm; (ix) 1700-1800 kg/mm; (x) 1800-1900 kg/mm; (xi) 1900-2000 kg/mm; (xii) 2000-2100 kg/mm; (xiii) 2100-2200 kg/mm; (xiv) 2200-2300 kg/mm; (xv) 2300-2400 kg/mm; (xvi) 2400-2500 kg/mm; (xvii) 2500-2600 kg/mm; (xviii) 2600-2700 kg/mm; (xix) 2700-2800 kg/mm; (xx) 2800-2900 kg/mm; (xxi) 2900-3000 kg/mm; (xxii) 3000-3100 kg/mm; (xxiii) 3100-3200 kg/mm; (xxiv) 3200-3300 kg/mm; (xv) 3300-3400 kg/mm; (xvi) 3400-3500 kg/mm; and (xvii) >3500 kg/mm, and/or [0068] (d) a thickness selected from the group consisting of: (i) <1 μm; (ii) 1-2 μm; (iii) 2-3 μm; (iv) 3-4 μm; (v) 4-5 μm; (vi) 5-6 μm; (vii) 6-7 μm; (viii) 7-8 μm; (ix) 8-9 μm; (x) 9-10 μm; (xi) >10 μm; and/or [0069] (e) a density selected from the group consisting of: (i) <3.0 g cm −3 ; (ii) 3.0-3.5 g cm −3 ; (iii) 3.5-4.0 g cm −3 ; (iv) 4.0-4.5 g cm −3 ; (v) 4.5-5.0 g cm −3 ; (vi) 5.0-5.5 g cm −3 ; (vii) 5.5-6.0 g cm −3 ; (viii) 6.0-6.5 g cm −3 ; (ix) 6.5-7.0 g cm −3 ; (x) 7.0-7.5 g cm −3 ; (xi) 7.5-8.0 g cm −3 ; (xii) 8.0-8.5 g cm −3 ; (xiii) 8.5-9.0 g cm −3 ; (xiv) 9.0-9.5 g cm −3 ; (xv) 9.5-10.0 g cm −3 ; (xvi) 10.0-10.5 g cm −3 ; (xvii) 10.5-11.0 g cm −3 ; (xviii) 11.0-11.5 g cm −3 ; (xix) 11.5-12.0 g cm −3 ; (xx) 12.0-12.5 g cm −3 ; (xxi) 12.5-13.0 g cm −3 ; (xxii) 13.0-13.5 g cm −3 ; (xxiii) 13.5-14.0 g cm −3 ; (xxiv) 14.0-14.5 g cm −3 ; (xxv) 14.5-15.0 g cm −3 ; (xxvi) 15.0-15.5 g cm −3 ; (xxvii) 15.5-16.0 g cm −3 ; (xxviii) 16.0-16.5 g cm −3 ; (xxix) 16.5-17.0 g cm −3 ; (xxx) 17.0-17.5 g cm −3 ; (xxxi) 17.5-18.0 g cm −3 : (xxxii) 18.0-18.5 g cm −3 ; (xxxiii) 18.5-19.0 g cm −3 ; (xxxiv) 19.0-19.5 g cm −3 ; (xxxv) 19.5-20.0 g cm −3 , and (xxxvi) >20.0 g cm −3 ; and/or [0070] (f) a coefficient of friction selected from the group consisting of: (i) <0.01; (ii) 0.01-0.02; (iii) 0.02-0.03; (iv) 0.03-0.04; (v) 0.04-0.05; (vi) 0.05-0.06; (vii) 0.06-0.07; (viii) 0.07-0.08; (ix) 0.08-0.09; (x) 0.09-0.10; and (xi) >0.1. [0071] The portion of the ion source having the first coating or surface is preferably selected from the group consisting of: (i) an ion chamber; (ii) a repeller electrode; and (iii) an exit plate or exit aperture arranged at the exit of the ion source through which ions of interest are desired to be transmitted. [0072] The ion source is preferably selected from the group consisting of: (i) an Electrospray ionisation (“ESI”) ion source; (ii) an Atmospheric Pressure Photo Ionisation (“APPI”) ion source; (iii) an Atmospheric Pressure Chemical Ionisation (“APCI”) ion source; (iv) a Matrix Assisted Laser Desorption Ionisation (“MALDI”) ion source; (v) a Laser Desorption Ionisation (“LDI”) ion source; (vi) an Atmospheric Pressure Ionisation (“API”) ion source; (vii) a Desorption Ionisation on Silicon (“DIOS”) ion source; (viii) an Electron Impact (“EI”) ion source; (ix) a Chemical Ionisation (“CI”) ion source; (x) a Field Ionisation (“FI”) ion source; (xi) a Field Desorption (“FD”) ion source; (xii) an Inductively Coupled Plasma (“ICP”) ion source; (xiii) a Fast Atom Bombardment (“FAB”) ion source; (xiv) a Liquid Secondary Ion Mass Spectrometry (“LSIMS”) ion source; (xv) a Desorption Electrospray Ionisation (“DESI”) ion source; (xvi) a Nickel-63 radioactive ion source; (xvii) an Atmospheric Pressure Matrix Assisted Laser Desorption Ionisation ion source; (xviii) a Thermospray ion source; (xix) an Atmospheric Sampling Glow Discharge Ionisation (“ASGDI”) ion source; and (xx) a Glow Discharge (“GD”) ion source. [0073] According to an aspect of the present invention there is provided a method of mass spectrometry comprising: [0074] ionising ions in an ion source having a first coating or surface provided on at least a portion of the ion source, wherein the first coating or surface comprises a ceramic coating or surface or a Diamond Like Carbon (“DLC”) coating or surface. [0075] According to an aspect of the present invention there is provided a method of making an ion source and/or one or more ionisation chambers and/or one or more repeller electrodes forming part of an ion source for a mass spectrometer comprising: [0076] depositing, sputtering or forming a first coating or surface on at least a portion of an ion source and/or one or more ionisation chambers and/or one or more repeller electrodes forming part of the ion source, wherein the first coating or surface comprises a ceramic coating or surface or a Diamond Like Carbon (“DLC”) coating or surface. [0077] The step of depositing, sputtering or forming the first coating or surface preferably comprises using a method selected from the group consisting of: (i) magnetron sputtering; (ii) closed field unbalanced magnetron sputter ion plating; (iii) electroplating; (iv) thermal spray coating; (v) vapour deposition; (vi) Chemical Vapour Deposition (“CVD”); (vii) combustion torch/flame spraying; (viii) electric arc spraying; (ix) plasma spraying; (x) ion plating; (xi) ion implantation; (xii) sputtering; (xiii) sputter deposition; (xiv) laser surface alloying; (xv) Physical Vapour Deposition (“PVD”); (xvi) plasma-based ion plating; (xvii) gas plasma discharge sputtering; (xviii) laser cladding; (xix) plasma enhanced Chemical Vapour Deposition; (xx) low pressure Chemical Vapour Deposition; (xxi) laser enhanced Chemical Vapour Deposition; (xxii) active reactive evaporation; (xxiii) Pulsed Laser Deposition (“PLD”); (xxiv) RF-sputtering; (xxv) Ion-Beam Sputtering (“IBS”); (xxvi) reactive sputtering; (xxvii) Ion-Assisted Deposition (“IAD”); (xxviii) high target utilisation sputtering; (xxix) High Power Impulse Magnetron Sputtering (“HIPIMS”); and (xxx) DC-sputtering. [0078] The step of depositing, sputtering or forming the first coating or surface preferably comprises creating a glow or RF discharge to the ion source and/or the one or more ionisation chambers and/or the one or more repeller electrodes forming part of the ion source in an atmosphere containing a hydrocarbon gas, wherein the glow or RF discharge causes a breakdown of the hydrocarbon gas so that carbon from the gas is deposited on the ion source and/or the one or more ionisation chambers and/or the one or more repeller electrodes forming part of the ion source. [0079] The step of depositing, sputtering or forming the first coating or surface preferably comprises applying a pulsed DC biased power supply to the ion source and/or the one or more ionisation chambers and/or the one or more repeller electrodes forming part of the ion source in an atmosphere containing a hydrocarbon gas, wherein the pulsed DC biased power supply causes a breakdown of the hydrocarbon gas so that carbon from the gas is deposited on the ion source and/or the one or more ionisation chambers and/or the one or more repeller electrodes forming part of the ion source. [0080] The hydrocarbon gas preferably comprises butane. [0081] The step of depositing, sputtering or forming the first coating or surface preferably further comprises simultaneously depositing a metal with the deposition of carbon from the hydrocarbon gas to form a Diamond Like Carbon coating or surface including a metal therein. The metal preferably comprises chromium. [0082] 4) Ion-Implanted Transition Metal—According to another aspect, there is provided a mass spectrometer comprising an ion source formed from titanium which has been subjected to ion implantation. [0083] The ion source preferably comprises one or more ionisation chambers formed from titanium which has been subjected to ion implantation. [0084] The ion source preferably further comprises one or more repeller electrodes formed from titanium which has been subjected to ion implantation. [0085] According to an embodiment: (i) at least 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 100% of an inner surface and/or an outer surface of the ion source has been subjected to ion implantation; and/or (ii) at least 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 100% of an inner surface and/or an outer surface of the one or more ionisation chambers has been subjected to ion implantation; and/or (iii) at least 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 100% of an inner surface and/or an outer surface of the one or more repeller electrodes forming part of the ion source has been subjected to ion implantation. [0086] The ion source and/or the one or more ionisation chambers and/or the one or more repeller electrodes forming part of the ion source preferably comprise titanium which has been subjected to ion implantation with ions selected from the group consisting of: (i) nitrogen; (ii) carbon; (iii) boron; (iv) oxygen; (v) argon; (vi) calcium; (vii) phosphorous; (viii) carbon-oxygen; (ix) neon; (x) sodium; (xi) chromium; (xii) vanadium; and (xii) fluorine. [0087] The ion source and/or the one or more ionisation chambers and/or the one or more repeller electrodes forming part of the ion source have preferably been subjected to an ion implantation dose selected from the group consisting of: (i) <10 13 ions/cm 2 ; (ii) 10 13 -10 14 ions/cm 2 ; (iii) 10 14 -10 15 ions/cm 2 ; (iv) 10 16 -10 16 ions/cm 2 ; (v) 10 16 -10 17 ions/cm 2 ; (vi) 10 17 -10 18 ions/cm 2 ; and (vii) >10 18 ions/cm 2 . [0088] The surface of the ion source and/or the one or more ionisation chambers and/or the one or more repeller electrodes forming part of the ion source which has been subjected to ion implantation preferably has either: [0089] (a) a resistivity selected from the group consisting of: (i) <10 −3 Ω-m; (ii) <10 −4 Ω-m; (iii) <10 −5 Ω-m; (iv) <10 −6 Ω-m; (v) <10 −7 Ω-m; (vi) 10 −3 -10 −4 Ω-m; (vii) 10 −4 -10 −5 Ω-m; (viii) 10 −5 -10 −6 Ω-m; and (ix) 10 −6 -10 −7 Ω-m; and/or [0090] (b) a Vickers hardness number or Vickers Pyramid Number (HV) selected from the group consisting of: (i) >1000; (ii) 1000-1100; (iii) 1100-1200; (iv) 1200-1300; (v) 1300-1400; (vi) 1400-1500; (vii) 1500-1600; (viii) 1600-1700; (ix) 1700-1800; (x) 1800-1900; (xi) 1900-2000; (xii) 2000-2100; (xiii) 2100-2200; (xiv) 2200-2300; (xv) 2300-2400; (xvi) 2400-2500; (xvii) 2500-2600; (xviii) 2600-2700; (xix) 2700-2800; (xx) 2800-2900; (xxi) 2900-3000; (xxii) 3000-3100; (xxiii) 3100-3200; (xxiv) 3200-3300; (xv) 3300-3400; (xvi) 3400-3500; and (xvii) >3500, wherein the Vickers hardness number or Vickers Pyramid Number is determined at a load of 30, 40, 50, 60 or 70 kg; and/or [0091] (c) a Vickers microhardness selected from the group consisting of: (i) >1000 kg/mm; (ii) 1000-1100 kg/mm; (iii) 1100-1200 kg/mm; (iv) 1200-1300 kg/mm; (v) 1300-1400 kg/mm; (vi) 1400-1500 kg/mm; (vii) 1500-1600 kg/mm; (viii) 1600-1700 kg/mm; (ix) 1700-1800 kg/mm; (x) 1800-1900 kg/mm; (xi) 1900-2000 kg/mm; (xii) 2000-2100 kg/mm; (xiii) 2100-2200 kg/mm; (xiv) 2200-2300 kg/mm; (xv) 2300-2400 kg/mm; (xvi) 2400-2500 kg/mm; (xvii) 2500-2600 kg/mm; (xviii) 2600-2700 kg/mm; (xix) 2700-2800 kg/mm; (xx) 2800-2900 kg/mm; (xxi) 2900-3000 kg/mm; (xxii) 3000-3100 kg/mm; (xxiii) 3100-3200 kg/mm; (xxiv) 3200-3300 kg/mm; (xv) 3300-3400 kg/mm; (xvi) 3400-3500 kg/mm; and (xvii) >3500 kg/mm, and/or [0092] (d) a thickness selected from the group consisting of: (i) <1 μm; (ii) 1-2 μm; (iii) 2-3 μm; (iv) 3-4 μm; (v) 4-5 μm; (vi) 5-6 μm; (vii) 6-7 μm; (viii) 7-8 μm; (ix) 8-9 μm; (x) 9-10 μm; (xi) >10 μm; and/or [0093] (e) a density selected from the group consisting of: (i) <3.0 g cm −3 ; (ii) 3.0-3.5 g cm −3 ; (iii) 3.5-4.0 g cm −3 ; (iv) 4.0-4.5 g cm −3 ; (v) 4.5-5.0 g cm −3 ; (vi) 5.0-5.5 g cm −3 ; (vii) 5.5-6.0 g cm −3 ; (viii) 6.0-6.5 g cm −3 ; (ix) 6.5-7.0 g cm −3 ; (x) 7.0-7.5 g cm −3 ; (xi) 7.5-8.0 g cm −3 ; (xii) 8.0-8.5 g cm −3 ; (xiii) 8.5-9.0 g cm −3 ; (xiv) 9.0-9.5 g cm −3 ; (xv) 9.5-10.0 g cm −3 ; (xvi) 10.0-10.5 g cm −3 ; (xvii) 10.5-11.0 g cm −3 ; (xviii) 11.0-11.5 g cm −3 ; (xix) 11.5-12.0 g cm −3 ; (xx) 12.0-12.5 g cm −3 ; (xxi) 12.5-13.0 g cm −3 ; (xxii) 13.0-13.5 g cm −3 ; (xxiii) 13.5-14.0 g cm −3 ; (xxiv) 14.0-14.5 g cm −3 ; (xxv) 14.5-15.0 g cm −3 ; (xxvi) 15.0-15.5 g cm −3 ; (xxvii) 15.5-16.0 g cm −3 ; (xxviii) 16.0-16.5 g cm −3 ; (xxix) 16.5-17.0 g cm −3 ; (xxx) 17.0-17.5 g cm −3 ; (xxxi) 17.5-18.0 g cm −3 ; (xxxii) 18.0-18.5 g cm −3 ; (xxxiii) 18.5-19.0 g cm −3 ; (xxxiv) 19.0-19.5 g cm −3 ; (xxxv) 19.5-20.0 g cm −3 ; and (xxxvi) >20.0 g cm −3 ; and/or [0094] (f) a coefficient of friction selected from the group consisting of: (i) <0.01; (ii) 0.01-0.02; (iii) 0.02-0.03; (iv) 0.03-0.04; (v) 0.04-0.05; (vi) 0.05-0.06; (vii) 0.06-0.07; (viii) 0.07-0.08; (ix) 0.08-0.09; (x) 0.09-0.10; and (xi) >0.1. [0095] The ion source is preferably selected from the group consisting of: (i) an Electrospray ionisation (“ESI”) ion source; (ii) an Atmospheric Pressure Photo Ionisation (“APPI”) ion source; (iii) an Atmospheric Pressure Chemical Ionisation (“APCI”) ion source; (iv) a Matrix Assisted Laser Desorption Ionisation (“MALDI”) ion source; (v) a Laser Desorption Ionisation (“LDI”) ion source; (vi) an Atmospheric Pressure Ionisation (“API”) ion source; (vii) a Desorption Ionisation on Silicon (“DIOS”) ion source; (viii) an Electron Impact (“EI”) ion source; (ix) a Chemical Ionisation (“CI”) ion source; (x) a Field Ionisation (“FI”) ion source; (xi) a Field Desorption (“FD”) ion source; (xii) an Inductively Coupled Plasma (“ICP”) ion source; (xiii) a Fast Atom Bombardment (“FAB”) ion source; (xiv) a Liquid Secondary Ion Mass Spectrometry (“LSIMS”) ion source; (xv) a Desorption Electrospray Ionisation (“DESI”) ion source; (xvi) a Nickel-63 radioactive ion source; (xvii) an Atmospheric Pressure Matrix Assisted Laser Desorption Ionisation ion source; (xviii) a Thermospray ion source; (xix) an Atmospheric Sampling Glow Discharge Ionisation (“ASGDI”) ion source; and (xx) a Glow Discharge (“GD”) ion source. [0096] Preferably, the portion of the ion source which has been subjected to ion implantation is selected from the group consisting of: (i) an ion chamber; (ii) a repeller electrode; and (iii) an exit plate or exit aperture arranged at the exit of the ion source through which ions of interest are desired to be transmitted. [0097] According to an aspect of the present invention there is provided a method of mass spectrometry comprising: [0098] ionising ions in an ion source formed from titanium which has been subjected to ion implantation. [0099] According to an aspect of the present invention there is provided a method of making an ion source and/or one or more ionisation chambers and/or one or more repeller electrodes forming part of an ion source for a mass spectrometer comprising: [0100] forming an ion source and/or one or more ionisation chambers and/or one or more repeller electrodes forming part of the ion source of a mass spectrometer from titanium; and [0101] subjecting the ion source and/or the one or more ionisation chambers and/or the one or more repeller electrodes forming part of the ion source to ion implantation. [0102] The ion source and/or the one or more ionisation chambers and/or the one or more repeller electrodes forming part of the ion source are preferably subjected to an ion implantation dose selected from the group consisting of: (i) <10 13 ions/cm 2 ; (ii) 10 13 -10 14 ions/cm 2 ; (iii) 10 14 -10 15 ions/cm 2 ; (iv) 10 15 -10 16 ions/cm 2 ; (v) 10 16 -10 17 ions/cm 2 ; (vi) 10 17 -10 18 ions/cm 2 ; and (vii) >10 18 ions/cm 2 . [0103] The method preferably further comprises accelerating ions to be implanted into the ion source and/or the one or more ionisation chambers and/or the one or more repeller electrodes forming part of the ion source to a kinetic energy selected from the group consisting of: (i) <10 keV; (ii) 10-50 keV; (iii) 50-100 keV; (iv) 100-150 keV; (v) 150-200 key; (vi) 200-250 keV; (vii) 250-300 keV; (viii) 300-350 key; (ix) 350-400 key; (x) 400-450 key; (xi) 450-500 keV; and (xii) >500 keV. [0104] According to another aspect of the present invention there is provided a mass spectrometer comprising an ion source formed from a transition metal which has been subjected to ion implantation. [0105] The transition metal is preferably selected from the group consisting of: (i) scandium; (ii) titanium; (iii) vanadium; (iv) chromium; (v) manganese; (vi) iron; (vii) cobalt; (viii) nickel; (ix) copper; (x) zinc; (xi) yttrium; (xii) zirconium; (xiii) niobium; (xiv) molybdenum; (xv) technetium; (xvi) ruthenium; (xvii) rhodium; (xviii) palladium; (xix) silver; (xx) cadmium; (xxi) lanthanum; (xxii) hafnium; (xxiii) tantalum; (xxiv) tungsten; (xxv) rhenium; (xxvi) osmium; (xxvii) iridium; (xxviii) platinum; and (xxix) gold. [0106] According to another aspect of the present invention there is provided a method of mass spectrometry comprising: [0107] ionising ions in an ion source formed from a transition metal which has been subjected to ion implantation. [0108] According to another aspect of the present invention there is provided a method of making an ion source and/or one or more ionisation chambers and/or one or more repeller electrodes forming part of an ion source for a mass spectrometer comprising: [0109] forming an ion source and/or one or more ionisation chambers and/or one or more repeller electrodes forming part of the ion source of a mass spectrometer from a transition metal; and [0110] subjecting the ion source and/or the one or more ionisation chambers and/or the one or more repeller electrodes forming part of the ion source to ion implantation. [0111] The transition metal is preferably selected from the group consisting of: (i) scandium; (ii) titanium; (iii) vanadium; (iv) chromium; (v) manganese; (vi) iron; (vii) cobalt; (viii) nickel; (ix) copper; (x) zinc; (xi) yttrium; (xii) zirconium; (xiii) niobium; (xiv) molybdenum; (xv) technetium; (xvi) ruthenium; (xvii) rhodium; (xviii) palladium; (xix) silver; (xx) cadmium; (xxi) lanthanum; (xxii) hafnium; (xxiii) tantalum; (xxiv) tungsten; (xxv) rhenium; (xxvi) osmium; (xxvii) iridium; (xxviii) platinum; and (xxix) gold. [0112] Preferably, the portion of the ion source which has been subjected to ion implantation is selected from the group consisting of: (i) an ion chamber; (ii) a repeller electrode; and (iii) an exit plate or exit aperture arranged at the exit of the ion source through which ions of interest are desired to be transmitted. [0113] The preferred embodiment relates to an EI or CI ion source wherein the ion source comprises titanium which has been subjected to ion implantation in order to passivate the surfaces of the EI or CI source region thereby reducing the surface reactions of molecules prior to ionisation. [0114] Preferably, the portion of the ion source having the first coating or surface is selected from the group consisting of: (i) an ion chamber; (ii) a repeller electrode; and (iii) an exit plate or exit aperture arranged at the exit of the ion source through which ions of interest are desired to be transmitted. [0115] The preferred embodiment relates to an EI or CI ion source wherein the ion source is provided with a surface coating. According to the preferred embodiment surface coatings and surface modification techniques are used to passivate the surfaces contained in an EI or CI source region thereby reducing the surface reactions of molecules prior to ionisation. [0116] Chemical standards were used to investigate the effects of the surface coating. The effects on full scan sensitivity/ionisation were observed. [0117] It is believed that the coated surface of the ion source according to the preferred embodiment reduces adsorption/degradation or decomposition of compounds upon contact with the surface prior to ionisation. Data has been produced to show that the chemical nature of the analyte seems to have a significant effect on the sensitivity. For example, a relatively polar compound (or one containing a polar moity or weak bonds prone to thermal degradation) can be detected with increased sensitivity from a coated volume according to an embodiment, in comparison to a cleaned stainless steel ion source. [0118] The preferred embodiment is particularly advantageous in that a clean conductive (or semi conductive) surface can be provided which is robust to abrasive cleaning and is inert. The surface reduces adsorption, catalysis and degradation/decomposition and hence visual residence time of the chemical within the source environment. The improved ion source also exhibits an increase in apparent sensitivity (compound dependant) and improved sample robustness/reproducibility. [0119] The preferred embodiment is concerned with an improved inert, semi-conductive inorganic metal complex coating on an ion source surface. [0120] In some preferred embodiments, the source volume, trap, repeller and ion exit plate of an ion source are coated with a preferred surface material. BRIEF DESCRIPTION OF THE DRAWINGS [0121] Various embodiments of the present invention will now be described, by way of example only, and with reference to the accompanying drawings in which: [0122] FIG. 1 shows a schematic diagram of an Electron Ionisation ion source according to an embodiment of the present invention; [0123] FIG. 2 shows a schematic diagram of an Chemical Ionisation ion source according to an embodiment of the present invention; [0124] FIG. 3 shows the chemical structure of 2,4 dinitorphenol; [0125] FIG. 4 shows the chemical structure of 4 amino biphenyl; [0126] FIG. 5 shows the chemical structure of phenobarbital; and [0127] FIG. 6 shows a comparison of the average intensities, siganal-to-noise, noise amplitude and area observed for three compounds with different ion sources. DETAILED DESCRIPTION [0128] Some preferred embodiments will now be described. FIG. 1 shows a schematic diagram of an Electron Ionisation ion source 1 comprising a housing 2 forming a chamber and a repeller electrode 3 . A neutral analyte gas is introduced from a gas chromatograph into the ion chamber 2 . An electron beam 4 is arranged to pass from a heated filament 5 to an electron collector 6 . Analyte gas molecules within the ion chamber 2 are preferably caused to interact with the electron beam 4 and as a result the analyte molecules are ionised and form analyte ions. The ionisation process is commonly referred to as being a hard ionisation process in that the analyte molecules fragment during the ionisation process. The resulting analyte fragment ions are repelled from the ion chamber 2 by the repeller electrode 3 . The analyte fragment ions may according to an embodiment pass through a lens system 7 before being onwardly transmitted in the direction shown by arrow 8 to subsequent vacuum stages of a mass spectrometer. [0129] FIG. 2 shows a Chemical Ionisation ion source 9 comprising an ion chamber 10 and optional ion repeller 11 . A heated filament 12 serves as an electron source and may according to one embodiment be located between an optional repeller plate 13 and an electron lens 14 . The electron lens 14 may comprise a plate with a rectangular slot or other shaped aperture aligned with the heated filament 12 . Electrons produced by the heated filament 12 are directed into the inside of the ion chamber 10 and preferably collide with neutral reagent gas molecules such as methane and ionise the reagent gas. The resulting reagent ions are then preferably caused to interact with neutral analyte molecules with the result that analyte ions are formed. Analyte ions may be repelled from the chamber 10 by an optional repeller electrode 11 or otherwise extracted from the chamber 10 . However, according to a preferred embodiment both the repeller plate 13 and the repeller electrode 11 are omitted. The analyte ions may pass through a lens system 12 prior to being onwardly transmitted to subsequent vacuum stages of a mass spectrometer. [0130] Source surface coatings which were applied to an Electron Ionisation ion source which was operated in an EI+ mode of operation were investigated using a mixture of semi polar GC amenable compounds. The effect on full scan sensitivity was investigated using a gas chromatograph with a tandem mass spectrometer. [0131] The EI ion source which was investigated comprised a source volume, a trap, a repeller and an ion exit plate. These components were all coated with titanium carbide in order to demonstrate the advantages of the preferred embodiment. [0132] The following results relate to data which was obtained from: (i) a standard used stainless steel ion source; (ii) an ion source wherein the ion source chamber and other components were coated with titanium carbide (TiC) according to an embodiment of the present invention; and (iii) a standard cleaned stainless steel ion source. [0133] The ion sources were investigated using a mixture of the following compounds: 2,4 dinitrobiphenol, 4 amino biphenyl and phenobarbital. The structures of 2,4 dinitrobiphenol, 4 amino biphenyl and phenobarbital are shown in FIGS. 3-5 respectively. [0134] FIG. 6 shows the ratio increase of the averaged surface coated and cleaned stainless steel ion sources against an uncleaned stainless steel ion source surface for the three compounds. Factor response differences for signal intensity, signal to noise, chemical noise amplitude and peak area are shown. [0135] The TiC coated ion source volume according to an embodiment of the present invention exhibited a signal intensity factor increase of 3.1 for 2,4 dinitrobiphenol compared to the aged stainless steel ion source. Similarly, the TiC coated ion source exhibited a signal intensity factor increase of 1.6 for 4 amino biphenyl and an increase of 2.5 for phenobarbital compared to the aged stainless steel ion source. [0136] The cleaned stainless steel ion source produced an immediate improvement in signal intensity compared to the aged stainless steel ion source for all the analytes by a factor of 1.6 for 2,4 dinitrobiphenol, by a factor of 3.3 for 4 amino-biphenyl and by a factor of 1.3 for phenobarbital. [0137] The signal improvements are greater for the TiC coated ion source according to an embodiment of the present invention but lower than the cleaned stainless steel ion source for 4 amino biphenyl. Of significance is the lower noise amplitude observed for the TiC coated ion source according to an embodiment of the present invention compared to the cleaned stainless steel ion source suggesting possible noise from the cleaning process. [0138] However, the noise amplitude for both the cleaned stainless steel ion source and the TiC coated ion source was higher than the used stainless steel ion source reducing the signal-to-noise (S:N) value while the TiC surface ion source increased the signal more than the noise resulting in an much improved S:N value for all the compounds. [0139] Additionally, the variation for three compounds under investigation of the TiC coated ion source according to an embodiment of the present invention against the cleaned stainless steel ion source are shown in FIG. 7 . Within the table format is included the factor response differences for the signal intensity, signal to noise ratio (RMS) chemical noise amplitude and peak area. [0140] An improvement in signal intensity, signal to noise (due to the relative drop in noise) and area counts were observed for both 2,4 dinitrophenol and phenobarbital. These compounds are of a more polar nature and have a potential reactive moiety present on the molecule. The TiC coated ion source provided lower sensitivity in scanning sensitivity for 4-aminobiphenyl compared to the cleaned stainless steel ion source. [0141] Though the above Description refers to a TiC-related example, more generally, some preferred coatings or layers include: 1) metallic carbide, such as TiC; 2) metallic boride; 3) ceramic or DLC, such as SiC; and 4) ion-implanted transition metals, such as ion-implanted titanium. [0142] Although the present invention has been described with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the scope of the invention as set forth in the accompanying claims.

A mass spectrometer includes an Electron Impact (“EI”) or a Chemical Ionisation (“CI”) ion source, and the ion source includes a first coating or surface. The first coating or surface is formed of a metallic carbide, a metallic boride, a ceramic or DLC, or an ion-implanted transition metal.

FIELD OF THE INVENTION [0001] The present invention generally relates to a door latch system for motor vehicles, and specifically to a door latch that does not release if the exterior door handle is moved open at a high speed. BACKGROUND OF THE INVENTION [0002] Various types of vehicle door latches and handles have been developed. The latch and handle assembly may include a handle that can be pulled outwardly by a user to release a door latch, thereby permitting the door to open. However, if a vehicle is subject to lateral acceleration due to a side impact such as a crash, the acceleration may cause the handle to shift outwardly due to its own mass, thereby causing the latch to release. Various counterweights and inertia locks have been developed to prevent inadvertent unlatching of a door latch during lateral acceleration of the vehicle. SUMMARY OF THE INVENTION [0003] One aspect of the present invention is a latch system for vehicle doors including a movable door handle and a door latch mechanism having latched and unlatched configurations. A first linkage is connected to the door handle such that movement of the door handle moves the first linkage. A second linkage is connected to the door latch mechanism such that movement of the second linkage causes the latch mechanism to shift from the latched configuration to the unlatched configuration. The latch system further includes a bypass mechanism having an engaged configuration in which the bypass mechanism interconnects the first and second linkages such that movement of the first linkage causes movement of the second linkage to thereby unlatch the latch mechanism. The bypass mechanism disconnects the first and second linkages when the bypass mechanism is in a bypassed configuration such that movement of the first linkage does not cause movement of the second linkage to unlatch the latch mechanism. The bypass mechanism further defines a home configuration. When the bypass mechanism is in its home configuration, movement of the first linkage at a first velocity relative to the second linkage causes the bypass mechanism to shift from its home configuration to its engaged configuration. When the bypass mechanism is in its home configuration, movement of the first linkage relative to the second linkage at a second velocity that is significantly greater than the first velocity causes the bypass mechanism to shift from its home configuration to its bypass configuration such that movement of the first linkage at the second velocity does not unlatch the latch mechanism. The bypass mechanism includes a locking member that is connected to a selected one of the first and second linkages. The locking member includes a first engagement surface and a retaining surface. The bypass mechanism further includes a lever support that is connected to the other of the first and second linkages. The bypass mechanism still further includes a lever that is movably connected to the lever support. The lever includes a second engagement surface that is configured to engage the first engagement surface, whereby the lever interconnects the lever support and the locking member when the bypass mechanism is in its engaged configuration. The lever engages the retaining surface when the bypass mechanism is in its home configuration to prevent the second engagement surface from engaging the first engagement surface. The lever support is disconnected from the locking member when the bypass mechanism is in its bypassed configuration. [0004] Another aspect of the present invention is a latch system for vehicle doors. The latch system includes a movable door handle, a door latch mechanism, and a bypass mechanism defining an engaged configuration, a bypass configuration, and a home configuration. The latch system further includes a linkage assembly including first and second linkages that are connected to the bypass mechanism to operably interconnect the door handle and the door latch mechanism when the bypass mechanism is in its engaged configuration. The bypass mechanism includes a locking member that is connected to the first linkage. The locking member defines an axis, and includes an end and an outer surface that is spaced from the axis a first distance. The locking member further includes an outer second surface at the end of the locking member that is spaced from the axis a second distance that is less than the first distance. The locking member further includes a recess that is disposed between the outer first and second surfaces. The bypass mechanism further includes a lever that is pivotably connected to the second linkage for rotation about a second axis that is transverse to the first axis. The lever includes a hooked end portion that slidably engages the outer first surface when the bypass mechanism is in its home configuration. If the door handle is moved from a rest position to an actuated position by a user, the hooked end portion rotates into engagement with the recess to interconnect the lever with the locking member such that the first and second linkages are interconnected, and movement of the door handle shifts the first and second linkages and unlatches the door latch mechanism. If the door handle is moved from a rest position to an actuated position at a relatively high velocity due to a vehicle crash, the hooked end of the lever slides on the first outer surface and moves across the recess without engaging the recess, and slidably engages the outer second surface, such that the first and second linkages are disconnected, and the movement of the door handle does not unlatch the door latch mechanism. [0005] Another aspect of the present invention is a vehicle door latch assembly including a door handle that is operably connected to a latch by first and second cables. The first and second cables are releasably interconnected by a spring-biased rotating lever having a hooked end. The hooked end slidably engages an outer surface of a locking member, and then engages a groove of the locking member to interconnect the first and second cables only if the door handle moves at a speed below a predefined speed. [0006] These and other aspects, objects, and features of the present invention will be understood and appreciated by those skilled in the art upon studying the following specification, claims, and appended drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0007] In the drawings: [0008] FIG. 1 is a partially fragmentary schematic side elevational view of a vehicle door including a latch system having a bypass device according to one aspect of the present invention; [0009] FIG. 2 is a partially fragmentary schematic top plan view of the vehicle door handle and latch system of FIG. 2 ; [0010] FIG. 3 is a cross sectional view of a bypass mechanism according to the present invention showing the bypass mechanism in a home configuration; [0011] FIG. 4 is a cross sectional view of the bypass mechanism of FIG. 3 showing the bypass mechanism in an engaged configuration; [0012] FIG. 5 is a cross sectional view of the bypass mechanism in a released configuration; [0013] FIG. 6 is a cross sectional view of the bypass mechanism showing the bypass mechanism as it shifts from a disengaged configuration or an engaged configuration to the home configuration of FIG. 3 ; and [0014] FIG. 7 is a fragmentary enlarged view of a portion of the lever and locking barrel of FIG. 6 . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0015] For purposes of description herein, the terms “upper,” “lower,” “right,” “left,” “rear,” “front,” “vertical,” “horizontal,” and derivatives thereof shall relate to the invention as oriented in FIG. 1 . However, it is to be understood that the invention may assume various alternative orientations, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise. [0016] With reference to FIG. 1 , a motor vehicle 1 includes one or more doors 2 that are movably mounted to a vehicle structure 6 by one or more hinges 4 A, 4 B. A movable exterior door handle 8 is connected to a latch mechanism 14 by first and second linkages such as cables 10 and 12 and a bypass mechanism 20 that selectively interconnects cables 10 and 12 . Latch mechanism 14 engages a striker 16 when the latch mechanism 14 is in a latched state or configuration to thereby selectively retain the door 2 in a closed position. Latch mechanism 14 and striker 16 may comprise a conventional latch mechanism and striker of a type that is well known in the art. As discussed in more detail below, when exterior door handle 8 is moved outwardly by a user, the bypass mechanism 20 mechanically interconnects the cables 10 and 12 such that movement of the exterior door handle 8 by a user unlatches the latch mechanism 14 so it is no longer latched to striker 16 , thereby permitting the door 2 to open (provided the latch mechanism 14 is not in a locked configuration). However, in the event of a vehicle crash/side impact resulting in rapid outward movement of exterior door handle 8 , the bypass mechanism 20 will mechanically disconnect first and second cables 12 such that the rapid movement of exterior door handle 8 does not unlatch the latch mechanism 14 . [0017] With reference to FIG. 2 , handle 8 may comprise a strap type handle of a known design having a body portion 18 defining a forward end 22 having a connecting structure 24 that rotatably engages a hinge pin or pivot 26 whereby the handle 8 rotates outwardly as shown by the arrow “A” about a vertical axis 28 relative to the door 2 to a released position shown in dashed lines 8 A. A spring such as torsion spring 25 biases the handle member 8 towards a closed position such that the handle 8 returns to the closed position after the handle 8 is released by a user. A rear end portion 30 of handle 8 is connected to an inner strand 32 of first cable 10 , such that outward movement of rear end portion 30 to the released position 30 A shifts strand 32 lengthwise. A first end of an outer sheath 34 of cable 10 is connected to a fitting 36 that is secured to the door 2 , and an opposite end of outer sheath 34 of cable 10 is connected to housing 42 of bypass mechanism 20 by a fitting 58 of a known type. Cable 12 may comprise an inner strand 38 and an outer sheath 40 . A first end of the outer sheath 40 is connected to housing 42 of bypass mechanism 20 utilizing a fitting 76 ( FIG. 3 ) of a known type, and the other end of outer sheath 40 is be connected to latch mechanism 14 utilizing a fitting 36 of a known type. The bypass mechanism 20 may be utilized in connection with a strap type exterior door handle 8 as shown in FIG. 2 , or the bypass mechanism 20 may be utilized in connection with other types of moveable exterior door handles that are known in the art. [0018] With further reference to FIG. 3 , the bypass mechanism 20 includes a main housing 44 having inner and outer cylindrical surfaces 46 and 48 , respectively and an end wall 50 having inner and outer surfaces 52 and 54 , respectively at a first end 56 of main housing 44 . A fitting 58 on end wall 50 connects the outer sheath 34 of cable 10 to the main housing 44 . A second or smaller housing 60 includes a first portion 62 having cylindrical inner and outer surfaces 64 and 66 , respectively, and an enlarged end portion 68 that is received in an open second end 70 of main housing 44 . The smaller housing 60 may be secured to the main housing 44 by welding, adhesives, crimping, or other suitable techniques. The housings 60 and 44 may be made from metal (e.g. steel), polymer, or other suitable material. The main housing 44 defines a generally cylindrical main cavity 72 , and the second housing 60 defines a generally cylindrical smaller second cavity portion that joins to the main cavity 72 . A fitting 76 is mounted on an end wall 78 of second housing 60 . The fitting 76 attaches the outer sheath 40 of second cable 12 to the second housing 60 . [0019] The bypass mechanism 20 also includes a lever support member 80 having a cylindrical outer surface 82 that slidably supports the lever support member 80 in the main housing 44 for reciprocating movement of lever support member 80 . End 84 of inner cable strand 32 is connected to lever support member 80 , such that lever support member 80 moves with inner cable strand 32 . A coil spring 86 is disposed around inner cable strand 32 between an end surface 88 of lever support member 80 and inner surface 52 of end wall 50 of main housing 44 . Coil spring 86 biases the lever support member 80 in the direction of the arrow “B” when coil spring 86 is compressed. Lever support member 80 includes a pair of extensions 90 that extend from end surface 92 of lever support member 80 to form a clevis 94 . A lever member 96 is rotatably connected to lever support member 80 at clevis 94 by a pin 98 . A second spring 102 is disposed in a cylindrical cavity 104 of lever support member 80 . The second spring 102 is a compression spring that bears against end surface 106 of lever member 96 to thereby bias the lever member 96 in the direction of the arrow “C” about the pin 98 . Second spring 102 may, alternatively, comprise a torsion spring (not shown) disposed about the pin 98 . As discussed in more detail below, the lever member 96 includes an end portion 108 that contacts a locking barrel member 110 when the bypass mechanism 20 is in the home configuration shown in FIG. 3 . [0020] Locking barrel member 110 includes an elongated body portion 112 having a cylindrical first outer surface 114 . The locking barrel member 110 is slidably disposed in the second cavity 74 of second housing 60 . The locking barrel member 110 is connected to the inner cable strand 38 of second cable 12 , such that the locking barrel member 110 and inner cable strand 38 move together. Locking barrel member 110 further includes an end portion 116 having a tapered, conical outer surface 118 , and a cylindrical second outer surface 120 . An annular groove 122 is disposed between the cylindrical first outer surface 114 and the cylindrical second outer surface 120 . Annular groove 122 is defined by a cylindrical surface 124 having a diameter that is significantly less than the diameters of the first and second outer surfaces 114 and 120 , and spaced apart side surfaces 126 and 128 . [0021] In use, when exterior door handle 8 is in a closed or non-actuated rest position, the bypass mechanism 20 is in a home position or configuration as shown in FIG. 3 . When bypass mechanism 20 is in the home configuration, end surface 130 of end 108 of lever member 96 is in sliding contact with cylindrical first outer surface 114 of locking barrel member 110 . The end surface 130 is biased into contact with the cylindrical first outer surface 114 by second spring 102 . If a user pulls outwardly on the exterior door handle 8 , inner cable strand 32 of first cable 10 will move in the direction of the arrow “D” ( FIG. 4 ). As the lever support member 80 moves in the direction of the arrow D, and the end 108 of lever member 96 will engage annular groove 122 due to the bias of second spring 102 . Side surface 132 of end 108 of lever member 196 then comes into contact with side surface 126 of annular groove 122 to thereby mechanically interconnect inner strands 32 and 38 of first and second cables 10 and 12 , respectively with respect to tension forces acting on cable strands 32 and 38 . Thus, as the exterior door handle 8 is pulled further towards its open position 8 A ( FIG. 2 ) movement of inner cable strand 32 causes movement of inner cable strand 38 . Movement of inner cable strand 38 causes latch mechanism 14 to unlatch, thereby permitting a user to open the vehicle door 2 . [0022] However, if the exterior door handle 8 is initially in a rest or non-actuated position, and the bypass mechanism 20 is in its home position or configuration ( FIG. 3 ), and if the exterior door handle 8 is moved outwardly at a high speed/velocity due to a side impact or the like, the bypass mechanism 20 will shift to the bypassed or disengaged configuration of FIG. 5 . When bypass mechanism 20 is in the bypassed configuration, cable strand 32 is mechanically disconnected from inner cable strand 38 such that movement of cable strand 32 does not result in movement of inner cable strand 38 . Thus, when bypass mechanism 20 is in its bypass configuration, movement of the exterior door handle 8 does not unlatch the latch mechanism 14 . [0023] The first cylindrical first outer surface 114 of locking barrel member 110 has a diameter that is somewhat greater than the diameter of cylindrical second outer surface 120 . If lever support member 80 is moved in the direction of the arrow D ( FIG. 4 ) at a relatively high speed/velocity, the end surface 130 of end 108 of lever member 96 initially slides on cylindrical first outer surface 114 of locking barrel member 110 . However, if lever support member 80 is moving at a relatively high velocity, the end surface 130 “jumps” across the annular groove 122 , and then slidably engages the cylindrical second outer surface 120 . The end surface 130 of lever member 96 then slides off the tapered outer end surface 118 of locking barrel member 110 , thereby shifting the bypass mechanism 20 to the bypassed or disconnected configuration of FIG. 5 . [0024] Although the second spring 102 biases the end 108 of lever member 96 towards the annular groove 122 , the second spring 102 may be selected to provide a relatively small biasing force such that the rotational inertia of lever member 96 results in a relatively slow rotational acceleration and velocity of lever member 96 as it slides off cylindrical first outer surface 114 . The mass/rotational inertia of lever member 96 and bias of second spring 102 , along with the dimensions of the cylindrical first outer surface 114 , cylindrical second outer surface 120 , and annular groove 122 can be selected such that the bypass mechanism 20 shifts to the engaged configuration ( FIG. 4 ) if handle 8 is moving at a relatively slow velocity, but shifts to the bypassed or disconnected configuration ( FIG. 5 ) if the exterior door handle 8 is moved at a relatively high speed/velocity. Specifically, a user will typically move the exterior door handle 8 outwardly at a speed that is less than 500 ms. Accordingly, the components of the bypass mechanism 20 can be selected such that the bypass mechanism 20 shifts from the home configuration ( FIG. 3 ) to the engaged configuration ( FIG. 4 ) if the exterior door handle 8 and cable 32 are moved at a speed of 500 ms or less. However, in the event the exterior door handle 8 moves outwardly at a relatively high velocity due to a side impact, the exterior door handle 8 will normally move at a speed of at least about 2000 ms to 2500 ms. Thus, the bypass mechanism 20 may be configured to shift from the home configuration ( FIG. 3 ) to the disconnected configuration ( FIG. 5 ) if the exterior handle and cable 32 move at a predefined speed that is significantly greater than 500 ms. In a preferred embodiment, the bypass mechanism 20 shifts from the home configuration ( FIG. 3 ) to the engaged configuration ( FIG. 4 ) if the exterior door handle 8 and cable 32 are moving at a speed greater than 1000 ms, and the bypass mechanism 20 shifts from the home configuration ( FIG. 3 ) to the bypass or disconnected configuration ( FIG. 5 ) if the exterior handle 8 and cable 32 are moving at a speed that is greater than 1000 ms. It will be understood that the various components of bypass mechanism 20 may be designed to provide a desired preselected speed at which the bypass mechanism 20 shifts from the home configuration to the disengaged configuration as required for a particular application. [0025] When the bypass mechanism 20 is in the engaged configuration ( FIG. 4 ) or the bypass configuration ( FIG. 5 ), the spring 86 is compressed, thereby generating a force tending to shift the lever support member 80 in the direction of the arrow “E” ( FIG. 6 ) Thus, after the exterior door handle 8 is released by a user, or as the exterior door handle 8 moves inwardly after a side impact due to the bias of spring 25 ( FIG. 2 ), the spring 86 will move the lever support member 80 towards the locking barrel member 110 to reset the bypass mechanism 20 . [0026] As shown in FIG. 7 , end portion 108 of lever member 96 may include a radiused edge portion 134 . The radiused edge portion 134 slidably engages an edge 136 of locking barrel member 110 as the lever support member 80 moves towards the locking barrel member 110 . The sliding engagement of the radiused edge 134 on the edge 136 causes the lever member 96 to rotate outwardly away from the annular groove 122 despite the rotational bias of spring 102 , and the force of spring 86 returns the bypass mechanism 20 to the home position ( FIG. 3 ) wherein the end surface 130 of lever member 96 engages cylindrical first outer surface 114 . [0027] Referring again to FIG. 7 , end 108 of lever member 96 may, alternatively, include a chamfer 138 instead of radiused edge 134 . Annular groove 122 may include a corresponding chamfer or ramp surface 140 rather than a side surface 128 . The chamfers 138 and 140 ensure that the lever member 96 shifts to the home position or configuration of FIG. 3 as the lever support member 80 moves towards the locking barrel member 110 due to the bias of spring 86 . For example, if the bypass mechanism 28 is in the engaged configuration ( FIG. 4 ), and the exterior door handle 8 is released, the end 108 of lever member 96 will move from the position of FIG. 4 to the home position of FIG. 3 due to the sliding engagement of chamfers 138 and 140 . [0028] It is to be understood that variations and modifications can be made on the aforementioned structure without departing from the concepts of the present invention, and further it is to be understood that such concepts are intended to be covered by the following claims unless these claims by their language expressly state otherwise.

A latch system for vehicle doors includes a bypass mechanism that mechanically disconnects a linkage assembly if an exterior door handle is moved towards an open position at a high speed. The bypass mechanism ensures that the door latch mechanism does not unlatch in the event a crash causes the exterior door handle to move open at a high speed, while providing for normal unlatching operation if the exterior door handle is opened at a relatively low velocity by a user.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to the production of full-color images and, more particularly, to the utilization of non-linear optics to form a multicolored laser beam. 2. Description of the Prior Art Various methods are presently being contemplated for use in forming multicolored laser beams for visual display applications. For example, a system utilizing an argon ion laser and a krypton ion laser has been developed by Spectra Physics Corporation and Coherent Radiation, Inc. However, the mixing ranges of such systems are limited by the emitted laser light wavelengths, which are 0.4880 micron, 0.5145 micron and 0.6471 micron. The efficiency of these systems is low and the lasers are large, bulky and heavy. Furthermore, the more powerful units require water-cooling. Other multicolored laser beam mixing schemes use dye lasers in addition to the ion lasers. Use of dye lasers results in even greater system complexity and higher cost than the argon/krypton scheme. OBJECT AND SUMMARY OF THE INVENTION It is a primary object of the present invention, therefore, to increase the mixing ranges of multicolored laser beams for visual display applications. It is another object to provide a multicolored laser beam which is highly efficient, rugged, and compact. Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing. In its broadest aspects the invention comprises a method for efficiently producing a multicolored laser beam. The second harmonic of a 1.06 micron wavelength laser beam is produced from a YAG laser. The second harmonic has a wavelength equal to 0.53 micron. The second and third harmonics of a 1.32 micron wavelength laser beam are simultaneously produced from a second YAG laser. The second harmonic has a wavelength equal to 0.66 micron and the third harmonic has a wavelength equal to 0.44 micron. The produced harmonics from the previous steps are combined to form a multicolored laser beam. Preferably, the first and second YAG lasers are diode laser pumped. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a chromaticity diagram illustrating the normal range of the human eye's sensitivity, the color range provided by the prior art, and the color range of the present invention. FIG. 2 is a schematic illustration of a preferred embodiment of the present invention. FIG. 3 is a schematic illustration of a second embodiment of the present invention. The same elements or parts throughout the figures are designated by the same reference characters. DETAILED DESCRIPTION OF THE INVENTION A chromaticity diagram is illustrated in FIG. 1. The normal range of the human eye's sensitivity (approximately 400 nm to 700 nm) is outlined by the curve designated 10. Current prior art proposed technology, utilizing an argon ion laser and a krypton ion laser limits colors to the area within the triangle ABC which is designated by the dashed line 12. The vertices (A,B,C) of the triangle are positioned on this chromaticity diagram by the principal wavelengths of the argon and krypton ion laser beams, i.e. λ=0.4880, and 0.5145 microns of the blue and green lines of the argon ion laser and λ=0.6471 micron of the red line ofthe krypton ion laser. Referring now to FIG. 2, a preferred embodiment of the present invention isdesignated generally as 13. A laser diode 14 optically pumps a YAG laser rod 16. The wavelength of the laser diode 14 is typically 0.8 micron. A coating 18 on one end of the YAG laser rod 16 transmits at a wavelength inthe vicinity of 0.8 micron and reflects at wavelengths in the 1.06 to 1.4 range. The output end of the laser rod has an optical coating 20 which is partially transmitting in the 1.06 to 1.4 micron range. Optical coating 20preferably provides maximum reflection at the diode laser pumping wavelength of around 0.8 micron. The resulting output laser beam 22, having a wavelength equal to 1.064 microns, is directed to a second harmonic generator (SHG) 24, thus, generating a green laser output beam 26with a wavelength of 0.532 micron. A second laser diode 28 optically pumps a second YAG laser rod 30. A coating 32 on one end of the second rod 30 transmits the laser diode output wavelength in the vicinity of 0.8 micron and maximally reflects at approximately 1.32 microns. The output end of this laser rod has a coating34 for partial transmittance at the 1.32 micron wavelength range. Coating 32 provides good reflectance at the pumping wavelength of 0.8 micron. The resulting output laser beam 36, having a wavelength equal to 1.32 microns,is directed to another non-linear optical component 3B that is designed to act both as a second harmonic generator (SHG) and a third harmonic generator (THG). The generated light beam 40 is directed to a dichroic beamsplitter 41 that separates the second and third harmonic laser beams, resulting in a red laser beam 42 with a wavelength of 0.66 micron and a blue laser beam 44 with a wavelength of 0.44 micron. The beams 26,42 and 44 are then combined to form a multicolored laser beam. The resulting chromaticity triangle 46 resulting from these three colors is shown with solid lines in FIG. 1 having vertices A', B', and C'. As noted by reference to this figure, the possible color arrangements are significantly increased over the contemplated prior art technique. Furthermore, it is noted that white light is designated by the point "W" in FIG. 1. In the prior art technique, this point is near the edge of the triangle. In the presently proposed technique, this point lies near the center of the triangle, as preferred. This provides improved excursion capability in color on the chromaticity diagram in all directions away from point "W". The present invention has several other advantages over currently practicedmethods which use the more conventional laser sources: 1. It is highly efficient, because the diode pumping scheme provides the optimal pump energy in the absorption band of the YAG solid state laser and because the pumping source, i.e. the diode laser, is inherently efficient. 2. The age limiting components are solid-state devices, which have experimentally demonstrated long lifetimes. Such solid-state components are inherently rugged. 3. The diode lasers which provide the pumping power for the YAG laser require only low voltages. Therefore, the low voltage in combination with the rugged construction provides high reliability. 4. Furthermore, the solid-state components result in small size and weight. The possibility of generating colors as proposed by the present applicant has been made possible by a series of breakthroughs in the optics field asenumerated below: 1. Highly efficient second and third harmonic generation of 1.064 and 1.32 microns laser radiation has been demonstrated. (See article by R. Steven Craxton of Laboratory of Laser Energetics, University of Rochester, "High Efficiency Frequency Tripling Schemes for High Powered Glass Lasers", IEE Journal of Quantum Electronics, Volume QE-17, September 81). 2. High Power--High efficiency laser diodes that emit in the 0.805 to 0.81 micron wavelength range are now increasingly available. This is an ideal wavelength for pumping YAG lasers (either pulsed or continuous wave). 3. YAG laser system that can emit continuous wave and pulsed radiation at the wavelengths of 1.06 microns and 1.319 microns are now commercially available (e.g., Quantronix Corporation, Amoco Laser Company). 4. Frequency doubling at a wavelength of 1.319 microns has been demonstrated (see, for example, doctoral thesis of Edward Sinowsky entitled "The Interferometric Measurement of Phase Mismatch in Potential Second Harmonic Generators", University of Arizona, University Optics Institute dated 1984). 5. Efficient frequency doubling of diode laser pumped YAG lasers, is now possible (e.g., Spectra Physics Corporation, Amoco Laser Company). 6. There have been recent breakthroughs in producing high efficiency non-linear optical materials such as potassium-titanyl phosphate (KPT). High resistance to optical damage coupled with high efficiency has allowedgeneration of tens of watts of second harmonic power at 0.53 micron wavelengths (see article by Gary T. Forrest, "Diode-Pumped Solid-State Laser Markets and Production Expand", Laser Focus/Electro-Optics. Volume 24, No. 6, June 1988 and article by William F. Krupke, "Prospects For Diode-Laser-Pumped Solid-state Lasers", Lasers & Optronics, March 1988, pages 79-84. 7. Diode laser array technology for achieving high power output is now available. This high output power is needed for high efficiency higher harmonic YAG operation. Referring now to FIG. 3, a second embodiment of the present invention is shown designated generally as 4B. In this instance, an array consisting ofa plurality of axially-spaced diode lasers 50 illuminates the cylindrical surface 52 of a YAG rod 54 for uniform illumination. Utilization of such an array provides high overall pump power available to the YAG rod 54. Thediode lasers 50 operating at an output wavelength of around 0.8 micron) areuniformly distributed along the length of the circumference of YAG rod 52. (FIG. 3 shows only one of the preferred YAG laser rods that would normallybe utilized.) The YAG rod may be cylindrical in shape (rotationally symmetrical) or it may be rectangular in cross section (slab shaped). Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understoodthat, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

A method for efficiently producing a multicolored laser beam. The second harmonic of a 1.06 micron wavelength laser beam is produced from a YAG laser. The second harmonic has a wavelength equal to 0.53 micron. The second and third harmonics of a 1.32 micron wavelength laser beam are simultaneously produced from a second YAG laser. The second harmoic has a wavelength equal to 0.66 micron and the third harmonic has a wavelength equal to 0.44 micron. The produced harmonics from the previous steps are combined to form a multicolored laser beam.

BACKGROUND OF THE INVENTION Compressed air-driven general purpose reciprocating piston material pumps may be damaged as a result of an empty supply container, interrupted material supply to the pump, ruptured hoses and excessive cavitation. There have in the past been provided runaway valves that automatically shut off the supply of compressed air to the pump in response to an air flow rate in excess of a predetermined flow rate in an effort to protect the pump from damage as a result of these causes. Such runaway valves are usually positioned in the supply air line between a pressure regulator and a piston reversing valve in the pump. All of the undesirable conditions noted above, i.e. empty supply container, interrupted material supply to the pump, ruptured hoses or excessive cavitation all result in a drop in pressure downstream from the runaway valve. Hence these runaway valves are designed to close when the pressure drop across the valve exceeds a predetermined maximum. However, since it is desirable to change the flow rate through the valve to control pump speed, this complicates the runaway valve construction since flow rate is proportional to pressure drop and hence flow rate variation undesirably changes the responsiveness of the runaway valve. In these prior runaway valves, after the valve closes in response to a predetermined downstream pressure drop, the valve remains in its closed position even though the condition causing the pressure drop has been corrected. Hence, a reset mechanism of some type is provided in the runaway valve to open the valve member after the downstream condition has been corrected. Usually this reset mechanism connects the inlet side of the valve to the outlet side across the poppet valve member and when downstream pressure approaches upstream pressure, a coil spring biasing the valve member moves it to its open position. This reset mechanism is slow-acting because the poppet valve member will not open until downstream pressure equals supply pressure, or approximately so, and hence the operator sometimes has to hold the reset mechanism for many seconds to be certain the valve member has been opened (remembering that he cannot visually see poppet valve member opening). Still another disadvantage in prior runaway valve mechanisms is that they are subject to transient upstream pressure surges and temporary downstream pressure losses. If the runaway valve experiences a transient upstream pressure increase or a temporary downstream pressure loss, and produces a pressure drop across the valve member above the predetermined value, the poppet valve member will move to a closed position and shut the pump down unnecessarily, and of course the operator then is required to manually reset the runaway valve to again connect supply air to the material pump and reinstate its operation. It is the primary object of the present invention to ameliorate the problems noted above in runaway valves for material pumps. SUMMARY OF THE PRESENT INVENTION In accordance with the present invention, an improved runaway protective valve is provided in the air supply line of a pnuematically driven material pump that shuts off the air supply when the air flow rate through the valve exceeds by a predetermined amount the pre-adjusted flow rate setting of the valve to prevent damage to the pump and conserve energy. This runaway valve includes a poppet valve member, directly in the main air flow passage biased to its open position by a spring, that closes upon a predetermined pressure drop through the passage. As downstream pressure drops a predetermined value in relation to upstream pressure, the poppet valve member will close against the biasing force of the spring and remain in that position until reset. Pump speed is controlled by varying air flow rate through the runaway valve and this is effected by an axially movable sleeve surrounding the valve member having a pair of spaced lands, one of which controls the effective area of an orifice to vary flow rate. Hence flow rate is controlled by varying flow area and not pressure drop so that the runaway valve member, which responds only to pressure drop across the valve member, closes at a flow rate above the preselected value rather than at a fixed flow rate. This first land on the sleeve, when the sleeve is shifted to its reset position, opens a bypass passage connecting the upstream side of the poppet to its downstream side, equalizing pressure across the valve and permitting the coil spring to move the valve from its closed position to its open position. Thus both flow control and poppet valve member reset is effected by the same sleeve in an uncomplicated, simple fashion. The movement of the poppet valve member to its closed position upon sensing a predetermined pressure drop is delayed for a predetermined time to prevent the valve from closing in response to transient upstream pressure surges and temporary downstream pressure drops. Toward this end the upstream side of the piston faces a closed chamber open to supply pressure only through a small vent hole. This restrictor and chamber on the upstream side of the poppet valve member create a time delay to the application of full upstream pressure to the upstream side of the piston. This prevents premature valve closing such as when a pump piston is changing direction of stroke or there is a small momentary disturbance of supply air pressure. Another aspect of the present invention is that supply air is not used to effect poppet valve member reset and hence valve reset occurs considerably more rapidly than in prior known runaway valves. Toward this end the second land on the sleeve when moved to its reset position isolates the valve member from supply pressure and the first land connects the downstream side of the poppet valve member through a bypass passage to the upstream poppet valve member chamber (then isolated from supply pressure) causing pressure to rapidly equalize across the valve and the valve to open without raising downstream pressure to the supply pressure value. This immediate opening of the runaway valve causes a temporary high pressure drop across the poppet valve member because of low downstream pressure, but the time delay vent hole and chamber prevent unwanted valve closing during this transient condition. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the present runaway valve in the air supply line to a material pump; FIG. 2 is an enlarged longitudinal section of the runaway protective fuse valve in accordance with the present invention illustrated in its maximum flow rate position; FIG. 3 is a longitudinal section of the present runaway protective fuse valve similar to FIG. 2 showing the valve in its minimum flow rate position; FIG. 4 is a longitudinal section of the present runaway protective fuse valve similar to FIG. 2 illustrating the valve in its closed position shutting off the supply of air to the pump; and FIG. 5 is a longitudinal section of the present runaway protective fuse valve similar to FIG. 4 with the valve in its closed position just prior to valve reset. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings and particularly to FIG. 1, a runaway valve 10 according to the present invention is illustrated in block diagram form in the air supply line for a material pump 12. The pump 12 is a general purpose reciprocating piston air-driven material pump usually mounted on the cover panel of a drum-type container that acts as a reservoir for the material to be pumped. In a typical system supply air 13 from a conventional air compressor system is delivered to the pump 12 through an air filter 14, an air pressure regulator 15, runaway valve 10, and a lubricator 16. The runaway valve 10 as viewed in FIG. 2 has an inlet fitting 18 that receives air from air regulator 15 and an outlet fitting 19 connected to deliver air to the pump 12 through lubricator 16. The runaway valve 10 generally includes a cylindrical body member 20 threadedly receiving inlet fitting 18 at one end and outlet fitting 19 at the other end, a shut-off poppet valve member 22 axially slidable in the body 20 to effect air flow shut-off, and a fine flow rate control and reset sleeve 24. The body member 20 has a stepped internal bore 25 that is divided and sealed by a cylindrical sealing disc 26 mounted in the bore seated against a stepped portion 27 therein. A frusto-conical valve seat 28 is formed in body bore 25 and forms a seat against which frusto-conical seating surface 29 on poppet valve member 22 engages when closed. Poppet valve member 22 is generally annular in configuration and is slidable in valve body bore portion 30 and defines with seal disc 26 a substantially closed chamber 32 on the upstream side of the poppet valve member 22. Valve member 22 includes a forward transverse portion 33 having a central forwardly extending projection 34 that defines an internal seat for a tapered coil compression spring 36 that continuously urges valve member 22 to its open position illustrated in FIGS. 2 and 3. Spring 36 is seated at its other end in an annular spring seat 37 threaded into the outlet end of the valve body bore 25. The poppet valve member 22 has an annular skirt portion 40 with an enlarged bore 41 therein defining part of chamber 32. The rear or upstream side of the valve member communicates with supply pressure through radial bore 44 in skirt 41, annular recess 45 and diagonal restrictor vent hole 46 in body member 20. The annular spring seat 37 is threadedly engaged with internal threads 39 in the left end of body member 20 as seen in FIG. 2 and is thereby axially adjustable in bore 25 to the right of its position shown against outlet fitting 19 to variably bias spring 36 and thus provide a coarse adjustment varying the flow rate at which valve 22 closes. A cross-pin 42 seated diametrally in spring seat 37 permits a needle-nose pliers to be inserted in outlet fitting 19 to rotate spring seat 37 and adjust it axially in bore 25. Seat 37 is shown in FIG. 2 in its low flow rate position, and its high flow rate position (its extreme right position) is limited by the end of threads 39. A plurality of annularly arrayed radial bores 48 in the valve body 20 on the upstream side of seal 26 permit inlet flow to pass outwardly from bore 25 around the poppet valve member 22 and thence pass radially inwardly through another annular array of radial bores 49 immediately upstream of valve seat 22, into the downstream end of bore 25. The valve body 20 has a plurality of spaced annular external lands 51, 52, 53 and 54 that slidably receive and align the flow control and reset sleeve 24 and with the sleeve 24 define flow rate control, poppet valve isolation and reset bypass valving functions. An annular filter screen 56 is mounted between the lands 52 and 53 to keep the poppet valve member 22 and chamber 32 free from any foreign material in the supply air. The sleeve 24 is annular in configuration and biased against a threaded adjusting nut 57 by a coil compression spring 58 that surrounds a reduced portion 59 on the left end of sleeve 24. Spring 58 reacts against a shoulder 61 on outlet fitting 19 and is held in alignment by a secondary surrounding sleeve 63 that has a radial flange 64 against which the movable end of spring 58 reacts. Flange 64 reacts against shoulder 65 on sleeve 24. Spaced internal sleeve lands 69 and 70 are formed in the sleeve. Land 69 is axially movable over valve body annular recess 72 to provide a variable flow area orifice in the main flow line of the valve. The land 70 is positioned so that in the high flow rate position of the sleeve 24 illustrated in FIG. 2 it is sufficiently far from land 53 to provide unrestricted flow of supply air, and in the reset position of the sleeve illustrated in FIG. 5 it covers valve land 53. In operation, the nut 57 is adjusted by rotation to axialy shift the sleeve 24 to provide the desired flow area at recess 72. This flow rate is controlled by varying the area of the orifice defined by the recess 72 and sleeve land 69. By moving the sleeve 24 to the position illustrated in FIG. 2 land 69 on the sleeve uncovers the recess 72 sufficiently to provide unrestricted flow and hence the maximum flow rate for the valve 10. Under normal operation air flows from inlet fitting 18 into valve body bore 25, out the valve body through radial bores 48 between the valve body 20 and the sleeve 24 in recess 67, into the radial passages 49 through open valve 22 and out fitting 19. Flow rate is reduced by rotating nut 57 in a direction to shift sleeve 24 to the right partly or completely closing recess 72. Flow rate is reduced to its minimum value by adjusting the sleeve 24 to the FIG. 3 position where sleeve land 69 partly covers body land 52. There is a slight clearance between land 69 and land 52 in this position that meters the minimum flow through the valve. If downstream pressure drops as a result of an empty material container, interrupted material supply to the pump, ruptured hose or excessive cavitation, the force of upstream pressure in chamber 32 acting on poppet valve 22 will shift the poppet valve to the left against valve seat 28 blocking the flow of air through the valve. Poppet valve 22 will remain in this closed position even though the downstream condition has been corrected because even though corrected, downstream pressure remains low and hence upstream pressure acting on the upstream side of valve member 22 will hold the valve closed. The valve is reset, i.e. the poppet valve is moved to its open position from its closed position illustrated in FIG. 4, by shifting the sleeve 24 to the position illustrated in FIG. 5. In this position the recess 67 in the sleeve 24 connects bypass ports 24 with chamber 32 behind poppet valve 22, permitting air to escape from the chamber to the downstream side of the poppet valve 22. This equalizes pressure on the opposite sides of the poppet valve and permits the spring 36 to shift the valve away from seat 28 back to its open position, illustrated in FIGS. 2 and 3. It should be noted that in the reset position of the sleeve 24 illustrated in FIG. 5, sleeve land 70 covers body land 53 isolating the valve chamber 32 from supply pressure Since chamber 32 is relatively small, pressure rapidly falls in that chamber during reset permitting very rapid opening of the valve member 22. This is in contrast to prior runaway valves that reset the valve by raising downstream pressure on the valve as opposed to lowering upstream pressure, as in the present device. Immediately after the valve member 22 is reset, and the sleeve 24 released so that it shifts back to its operating position, air flow will begin through radial passages 49 to the pump. For a short time, however, downstream pressure may continue to be low, but the time delay effect of chamber 32 and restrictor 46 prevent the poppet valve 22 from closing during this transient condition because they form a time-delay between inlet pressure variation and the pressure on the upstream side of the valve 22. Downstream pressure then increases to its normal value and prevents the poppet valve 22 from closing as pressure on the upstream side of the valve 22 approximately reaches supply pressure. The time-delay function of the restrictor 46 and chamber 32 also prevent transient surges in upstream pressure and temporary drop of downstream pressure from unnecessarily closing valve member 22.

A runaway valve for an air-driven material pump that shuts off air flow to the pump when air flow rate exceeds a predetermined setting to prevent pump damage, wherein the valve includes a flow-responsive poppet valve member and an axially movable sleeve finely adjustable about a first position to select flow rate, and movable to a second position to interconnect the upstream and downstream sides of the poppet valve member to effect reset. A closed chamber with a vent hole buffers the upstream side of the poppet valve member from inlet pressure to delay valve closing and compensate for pressure transients. In its reset position, the sleeve isolates this chamber from inlet pressure to achieve faster reset.

This application claims the benefit of U.S. provisional application Ser. No. 60/056,165, filed Aug. 19, 1997. BACKGROUND OF THE INVENTION This invention relates to static random access memory circuits, and more particularly to static random access memory circuits that are especially suitable for such purposes as inclusion on programmable logic integrated circuit devices for programmable control of the configuration of those devices. One example of a known programmable logic device 500 is shown in FIG. 1. Device 500 may be generally like the programmable logic devices shown and described in Cliff et al. U.S. Pat. No. 5,689,195, which is hereby incorporated by reference herein. Device 500 includes a plurality of regions 510 of programmable logic disposed on the device in a two-dimensional array of intersecting rows and columns of such regions. Each region includes a plurality of subregions 512 of programmable logic. For example, each subregion 512 may include a four-input look-up table which is programmable to produce a "combinatorial" output signal which can be any logical combination of four input signals applied to the look-up table. Each subregion 512 may additionally include a register (e.g., a flip-flop) for selectively registering (storing) the combinatorial output signal to produce a registered output signal. And each subregion 512 may include programmable logic connectors ("PLCs") for programmably selecting either the combinatorial or registered output signal as the final output signal of the subregion. A plurality of horizontal interconnection conductors 520 is associated with each row of regions 510 for conveying signals to, from, and/or between the regions in the associated row. A plurality of vertical interconnection conductors 530 is associated with each column of regions 510 for conveying signals to, from, and/or between the various rows. A plurality of local conductors 540 is associated with each region 510 for making selected signals on the adjacent horizontal conductors 520 available to the associated region. PLCs 522 are provided for making programmable connections between selected intersecting conductors 520 and 540. A plurality of subregion feeding conductors 550 is associated with each subregion 512 for applying selected signals on the adjacent conductors 540 (and adjacent local feedback conductors 560 (described below)) to the associated subregion. PLCs 542 are provided for making programmable connections between intersecting conductors 540/560 and 550. The output signal of each subregion 512 can be applied to selected adjacent vertical conductors via PLCs 562 and/or to selected horizontal conductors 520 via PLCs 564. The output signal of each subregion 512 is also made available as a local feedback signal (via a conductor 560) to all of the subregions in the region 510 that includes that subregion. Selected intersecting horizontal and vertical conductors are programmably interconnectable by PLCs 532. Another example of a known programmable logic device 600 is shown in FIG. 2. Device 600 may be generally like the programmable logic devices shown in Freeman U.S. Pat. No. Re. 34,363, which is also hereby incorporated by reference herein. Device 600 includes a plurality of configurable logic blocks ("CLBs") 610 disposed on the device in a two-dimensional array of intersecting rows and columns of CLBs. Each CLB 610 may include one or two small, programmable, look-up tables and other circuitry such as a register and PLCs for routing signals within the CLB. A plurality of horizontal interconnection conductor tracks 620 are disposed above and below each row of CLBs 610. A plurality of vertical interconnection conductor tracks 630 are disposed to the left and right of each column of CLBs 610. Local conductors 640 are provided for bringing signals into each CLB 610 from selected conductor tracks 620/630 adjacent to each side of the CLB and/or for applying signals from the CLB to selected adjacent conductor tracks 620/630. PLCs 622/632 are provided for making programmable connections between selected intersecting conductors 620/630 and 640. PLCs 624 are provided for making programmable connections between selected conductors segments in tracks 620 and/or 630 that intersect or otherwise come together at the locations of those PLCs. In programmable logic devices such as those shown in FIGS. 1 and 2, first-in/first-out ("FIFO") chains of static random access memory ("SRAM") cells are commonly used on the device for programmable control of the configuration of the device. For example, the SRAM cells in such FIFO chains may be used to control the logic performed by each subregion 512 or CLB 610 (e.g., by constituting or controlling the data stored in the look-up tables in those components and by controlling the connections made by the PLCs in those components). The SRAM cells in the FIFO chains may also be used to control the connections made by the various interconnection conductor PLCs (e.g., PLCs 522, 532, 542, 562, 564, 622, 624, and 632) on the device. A typical prior art FIFO SRAM chain 10 will now be described with reference to FIG. 3. In the FIFO SRAM chain 10 shown in FIG. 3, each SRAM cell 20 includes a relatively strong, forwardly directed inverter 22 connected in a closed loop series with a relatively weak, backwardly directed inverter 24. In the absence of a signal passed from above by an NMOS pass gate 14, each inverter 24 is strong enough to hold the associated inverter 22 in whatever state it was left by the most recent signal passed by the pass gate 14 immediately above. On the other hand, each inverter 24 is not strong enough to prevent the associated inverter 22 from responding to any signal passed by the pass gate 14 immediately above. Programming data is applied to FIFO chain 10 via DATA IN lead 12 at the start of the chain. Initially all of pass gates 14 are enabled by address signals ADDR-1 through ADDR-N. This allows the first programming data bit to pass all the way down the chain (inverted by each successive inverter 22 that it passes through) until it reaches and is stored in cell 20-N. Pass gate 14-N is then turned off by changing the ADDR-N signal to logic 0. The next programming data bit from lead 12 therefore passes down the chain until it reaches and is stored in the cell immediately above cell 20-N (not shown but similar to all other cells 20). The NMOS pass gate 14 above the cell above cell 20-N is then turned off and the next programming data bit is applied to lead 12. This process continues until all of cells 20 have been programmed and all of pass gates 14 have been turned off. Each cell 20 outputs the data it stores via its DATA OUT lead. These DATA OUT signals may be used to control various aspects of the operation of a programmable logic device that includes chain 10. For example, a DATA OUT signal from chain 10 may control a programmable aspect of the "architecture" of the programmable logic device (e.g., which of several available clock or clear signals a register in a subregion 512 (FIG. 1) or a CLB 610 (FIG. 2) responds to). Or a DATA OUT signal from chain 10 may control a programmable aspect of the logic performed by the device (e.g., by being a datum in a look-up table in a subregion 512 or a CLB 610). As still another example, a DATA OUT signal from chain 10 may control an interconnection conductor PLC (e.g., a PLC 522, 532, etc. (FIG. 1), or a PLC 622, 624, etc. (FIG. 2)) on the device. The contents of chain 10 may be verified by using the ADDR signals to enable pass gates 14 progressively from the bottom up. This allows the data in cells 20 to be read out one after another from the bottom up via VERIFY lead 16. It will be apparent from the foregoing that in order to program or verify chain 10 each NMOS pass gate 14 must be able to effectively pass both logic 0 and logic 1 signals. When circuit components are made very small (as is becoming possible as a result of on-going advances in the techniques for semiconductor fabrication) and VCC (the power voltage used for logic 1 signals) is accordingly reduced, an NMOS pass gate 14 may not be able to pass a logic 1 signal that is sufficiently strong to overwrite the logic 0 output of the inverter 24 below it unless the pass gate is made undesirably large. Any unipolar MOS (i.e., NMOS or PMOS) pass gate will have this or a similar problem in these circumstances. Thus a PMOS pass gate does not pass logic 0 very well under the above-described conditions that reduce the effectiveness of an NMOS pass gate in passing logic 1. FIFO SRAM chains are therefore becoming less satisfactory for use as the programmable elements in products such as programmable logic devices. In view of the foregoing, it is an object of this invention to provide improved SRAMs for use on programmable logic devices or in other similar contexts. It is a more particular object of this invention to provide SRAMs that can be used on programmable logic devices that are made using advanced integrated circuit fabrication techniques and therefore with extremely small circuit components and/or with the intention of using relatively low VCC potential. SUMMARY OF THE INVENTION These and other objects of the invention are accomplished in accordance with the principles of the invention by providing an SRAM made up of SRAM cells, all of which store a first of two logic states when the SRAM is initialized, and which are individually or specifically addressed during programming mode when it is desired to change the state of an addressed cell to the second of the two logic states. In addition, the address connection of each cell is such that the cell is changed to the second logic state by passing a logic 0 signal through an NMOS pass gate to the cell, or by passing a logic 1 signal through a PMOS pass gate to the cell. Even NMOS pass gates that are too small to reliably pass logic 1 signals pass logic 0 signals perfectly satisfactorily. Similarly, even PMOS pass gates that are too small to reliably pass logic 0 signals pass logic 1 signals satisfactorily. The data input terminal of each SRAM cell can also be used to verify the contents of the cell after programming. To verify a cell's contents, a lead that is used to supply data to the cells during programming is charged to the second logic state and then weakly held at that potential. The cell to be verified is then addressed to connect the data input terminal of the cell to the above-mentioned data input lead. If the cell has the first logic state, the cell will not try to discharge the data input lead, which will therefore remain at the second logic potential. On the other hand, if the cell is at the second logic potential, the cell will gradually discharge the data input lead to the first logic potential (although the cell itself will not change from the second logic state to the first logic state). Thus the potential on the data input lead after the foregoing operations can be used to verify the contents of the SRAM cell being tested. Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a simplified schematic block diagram of a representative portion of illustrative conventional programmable logic device circuitry with which this invention can be used. FIG. 2 is similar to FIG. 1, but for another example of conventional programmable logic device circuitry with which the invention can be used. FIG. 3 is a simplified schematic diagram of a conventional FIFO SRAM chain. FIG. 4 is a simplified schematic block diagram of representative portions of an illustrative embodiment of an SRAM constructed in accordance with this invention. FIG. 5 is a more detailed schematic diagram of an illustrative embodiment of a representative portion of the circuitry shown in FIG. 4. FIG. 6 is a diagram similar to FIG. 4 showing an alternative illustrative embodiment of an SRAM constructed in accordance with the invention. FIG. 7 is a simplified block diagram of an illustrative embodiment of a system which includes a programmable logic device configured by an SRAM of this invention, all in accordance with the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A representative portion of an illustrative embodiment of SRAM circuitry 110 in accordance with this invention is shown in FIG. 4. SRAM circuitry 110 includes any desired number of SRAM cells 120, each of which is selectively connectable to a common DATA IN lead 112 via a respective NMOS pass gate 114. Each SRAM cell 120 includes a relatively strong inverter 122 connected in a closed loop series with a relatively weak inverter 124. A more detailed circuit diagram of a representative SRAM cell 120 is shown in FIG. 5 and described later in this specification. The output terminal of each SRAM cell's strong inverter 122 is the DATA OUT lead of that cell. Assuming that SRAM circuitry 110 is included on a programmable logic device, the DATA OUT signals of that circuitry can be used in any way that the DATA OUT signals in FIG. 3 can be used to programmably control various aspects of the connectivity and operation (generically the "configuration") of the programmable logic (e.g., as described above in connection with FIGS. 1-3 for the illustrative programmable logic device organizations shown in FIGS. 1 and 2). The DATA OUT terminal of each SRAM cell is also selectively connectable to VSS (logic 0 (ground)) via an associated NMOS pass gate 126. All of gates 126 are enabled in parallel by a logic 1 signal applied to the CLEAR lead. VCC charging circuit 130, week pull up circuit 140, and level detection circuit 150 are used only during operation of the circuitry to verify the contents of SRAM cells 120. These circuit components are therefore initially inoperative and have no effect on the circuitry. To program memory circuitry 110 all of pass gates 114 are disabled by logic 0 address signals ADDR-1, ADDR-2, etc. All cells 120 are then cleared by causing the CLEAR signal to go to logic 1. This enables all of pass gates 126, thereby applying logic 0 to the input terminal of the inverter 124 in each cell 120. The resulting logic 1 output of each inverter 124 causes the output of the associated inverter 122 to become logic 0, thereby holding the DATA OUT signal of each cell 120 at logic 0 even after the CLEAR signal returns to logic 0. After all of cells 120 have been cleared to logic 0 as described above, elements 112 and 114 are used to write logic 1 into only those cells that need to be programmed to logic 1. Logic 0 is applied to DATA IN lead 112. Then logic 1 is applied (sequentially or simultaneously as desired) to the ADDR leads of the pass gates 114 of only those cells 120 that need to be switched from logic 0 to logic 1. Enabling the pass gate 114 of a cell in this way causes the logic 0 signal on DATA IN lead 112 to be applied to the input terminal of that cell's inverter 122. This causes the output terminal of that inverter (and therefore the DATA OUT signal of that cell) to switch to logic 1. The associated inverter 124 operates to hold that inverter 122 in the logic 1 output condition even after the associated ADDR signal switches back to logic 0, thereby disconnecting the memory cell from DATA IN lead 112. This completes the process of programming cells 120. In actual practice in which the circuitry shown in FIG. 4 is repeated a number of times but with the ADDR signals shared by all the repetitions, it may be necessary, when enabling a particular address line as described above, to apply logic 1 to the DATA IN leads 112 of any repetitions in which the addressed SRAM cells 120 are not to be programmed logic 1. This will prevent inadvertent switching from logic 0 to logic 1 of SRAM cells 120 that are not to be so switched. Structures including repetitions of the FIG. 4 circuitry are discussed in more detail below. From the foregoing it will seen that all cells 120 are initially cleared to logic 0. Then only those cells requiring programming to logic 1 are addressed and overwritten with logic 1. To do this overwriting, the NMOS pass gates of the cells to be overwritten are only required to pass logic 0, which they do very well even when they are made very small. The circuitry also operates very well with relatively low VCC (logic 1 (power)) voltage or potential, since pass gates 114 are not required to pass logic 1 in order to program cells 120. After cells 120 have been programmed as described above, their contents can be verified as will now be described. DATA IN lead 112 is first isolated from other signal sources such as the data signal source. VCC charging circuit 130 is then turned on via its control lead 132 to charge lead 112 to logic 1. Circuit 130 is then turned off and weak pull up circuit 140 is turned on via its control lead 142 to apply a weak pull up (logic 1) signal to lead 112. A logic 1 signal is then applied to the ADDR lead of the memory cell 120 whose content is to be verified. This turns on the associated NMOS pass gate 114. If the cell 120 being verified is storing logic 0, the output of that cell's inverter 124 will be logic 1 and there will be no tendency of the voltage on lead 112 to drop from logic 1. On the other hand, if the cell 120 being verified is storing logic 1, the output signal of that cell's inverter 124 will be logic 0, which will cause the voltage on lead 112 to gradually fall from logic 1 toward logic 0. (Under these conditions, the logic 1 signal from lead 112 is not strong enough to change the state of the cell 120 being verified.) Level detection circuit 150 is turned on via its control lead 152 a suitable time interval after the transistor 114 of the cell being verified is turned on. If the voltage on lead 112 is still logic 1, circuit 150 produces a VERIFY output signal which indicates that the cell being verified is storing logic 0. On the other hand, if the voltage on lead 112 has fallen to logic 0 (or sufficiently far toward logic 0), circuit 150 produces a VERIFY output signal which indicates that the cell being verified is storing logic 1. The foregoing verification steps are repeated for each cell 120 along line 112 to be verified. It will be noted that the above-described verification process is not destructive of the data stored in cells 120. A programmable logic device will typically include several repetitions of the FIG. 4 circuitry (i.e., several parallel DATA IN leads 112 and associated circuitry). The ADDR-1, ADDR-2, etc., signals will be shared by all of these parallel SRAM strings. In particular, one SRAM cell 120-1 in each string will be controlled by a common ADDR-1 signal, another one SRAM cell 120-2 in each string will be controlled by a common ADDR-2 signal, and so on. Thus (as has already been mentioned) when it is desired to program the SRAM cells controlled by any particular address signal, it may be necessary to apply logic 1 to some DATA IN lines 112 to prevent the associated SRAM cells from inadvertently switching from their initial logic 0 output condition. An illustrative embodiment of a representative SRAM cell 120 is shown in more detail in FIG. 5. Relatively strong inverter 122 is made up of P-channel transistor 122a and N-channel transistor 122b. Relatively weak inverter 124 is made up of P-channel transistor 124a and N-channel transistor 124b. In order for clear pass gate 126 to reset cell 120 to logic 0 as described above, the conductance of transistor 126 should be greater than the conductance of transistor 122a. In order for a logic 0 data signal on lead 112 to cause cell 120 to switch from a reset logic 0 data output to a logic 1 data output as described above, the conductance of transistor 114 should be greater than the conductance of transistor 124a. In order to use lead 112 to verify the contents of cell 120 as described above, the conductance of transistor 124b should be greater than the conductance of transistor 114. This conductance relationship can be satisfied by making transistors 124b and 114 the same size because lower Vgs and body effect decreases the conductance of transistor 114 as the data input terminal 115 of cell 120 begins to rise in voltage. FIG. 6 shows an alternative embodiment of the FIG. 4 circuitry in which elements 114 and 126 are converted from NMOS pass gates to PMOS pass gates 214 and 226. Other appropriate modifications are also made, but generally similar elements in FIGS. 4 and 6 have their reference numbers increased by 100 in FIG. 6. To program the FIG. 6 circuitry 210 all SRAM cells 220 are preset to logic 1. This is done by applying logic 0 to the CLEAR bar lead. Thereafter, to switch the SRAM cells 220 that need to be switched to logic 0, logic 1 is applied to DATA IN bar lead 212 and logic 0 is applied to the ADDR bar lead for each SRAM cell that needs to be switched. This turns on the PMOS pass gate 214 receiving that ADDR bar signal, thereby allowing that pass gate 214 to pass logic 1 from lead 212. This in turn switches the DATA OUT of the associated SRAM cell 220 to logic 0. Again, assuming that SRAM circuitry 210 is included on a programmable logic device, the DATA OUT signals of that circuitry can be used in any way that the DATA OUT signals in FIGS. 3 and 4 can be used to control the configuration of the associated programmable logic device. Verification of the contents of SRAM cells 220 is similar to verification of the contents of SRAM cells 120 except that the polarity is reversed. Thus DATA IN bar lead 212 is first charged to logic 0 by VSS charging circuit 230. Then weak pull down circuit 240 is placed in operation to weakly hold lead 212 at logic 0. Next, logic 0 is applied to the ADDR bar lead of the pass gate 214 associated with the SRAM cell whose content is to be verified. If that SRAM cell is outputting logic 1, the inverter 224 in that cell will be outputting logic 0 and there will be no effect on the logic 0 potential of lead 212 as a result of enabling the pass gate 214 between those elements. Level detection circuit 250 will therefore detect no change in the potential of lead 212, and circuit 250 will accordingly produce a VERIFY output signal which indicates that the SRAM cell 220 being verified is storing logic 1. On the other hand, if the SRAM CELL 220 being verified is outputting logic 0, the inverter 224 in that SRAM cell will be outputting logic 1. This will cause the potential on lead 212 to rise when the pass gate 214 associated with that SRAM cell is enabled. This change in the potential on lead 212 is detected by level detection circuit 250, which consequently produces a VERIFY output signal indicating that the SRAM cell being verified is storing logic 0. FIG. 7 illustrates a programmable logic device 402 (which includes one or more SRAMs 110 or 210 in accordance with this invention for programmable control of the configuration of the programmable logic device) in a data processing system 400. The circuitry of device 402 which is controlled by SRAM(s) 110 or 210 may be organized as shown in FIG. 1 or 2 or in any other desired way. In addition to device 402, data processing system 400 may include one or more of the following components: a processor 404; memory 406; I/O circuitry 408; and peripheral devices 410. These components are coupled together by a system bus 420 and are populated on a circuit board 430 which is contained in an end-user system 440. System 400 can be used in a wide variety of applications, such as computer networking, data networking, instrumentation, video processing, digital signal processing, or any other application where the advantage of using reprogrammable logic is desirable. Programmable logic device 402 can be used to perform a variety of different logic functions. For example, programmable logic device 402 can be configured as a processor or controller that works in cooperation with processor 404. Programmable logic device 402 may also be used as an arbiter for arbitrating access to a shared resource in system 400. In yet another example, programmable logic device 402 can be configured as an interface between processor 404 and one of the other components in system 400. It should be noted that system 400 is only exemplary, and that the true scope and spirit of the invention should be indicated by the following claims. It will be understood that the foregoing is only illustrative of the principles of the invention, and that various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention.

A static random access memory ("SRAM") that is especially suitable for such uses as inclusion on a programmable logic device to provide programmable control of the configuration of that device. The SRAM includes a plurality of SRAM cells, all of which are simultaneously cleared to a first of two logic states by application of a second of the two logic states to clear terminals of the cells. Any cell that needs to be programmed to the second of the two logic states is thereafter specifically addressed and a data signal thereby applied which programs the cell to the second logic state. The cells are preferably constructed so that they are programmed to the second logic state by application of a data signal having the first logic state. Even a very small unipolar MOS pass gate transistor can therefore be used as the addressable path through which the data signal is applied. The memory may also include circuitry for verifying the contents of each cell via the data input terminal of the cell.

This application is a continuation of U.S. patent application Ser. No. 13/008,818 filed Jan. 18, 2011, pending, which is a continuation U.S. patent application Ser. No. 11/817,490 filed Aug. 30, 2007, which is a national stage of PCT/EP2006/002330 filed Mar. 14, 2006, which is based on and claims priority of European Patent Application 05006790.9 filed Mar. 29, 2005, the entire contents of each of which are incorporated by reference herein. BACKGROUND 1. Field of the Invention The invention is related to mobile communications systems. More specifically, it relates to context transfer for seamless inter-domain handover support in heterogeneous networks. 2. Description of the Related Art The main property of 4G mobile communication networks is the heterogeneity of radio and network technologies. A 4G network can be regarded as an integrated system composed of various networks that present themselves as one network to the end user, with Internet Protocol (IP) as a common basis. A challenge is to provide seamless mobility in such a heterogeneous environment to support interactive applications such as Voice over Internet Protocol (VoIP) telephony. An IP-based heterogeneous network architecture is assumed, consisting of several inter-connected networks, which may use different network technologies (e.g. Differentiated Services Quality of Service DiffServ QoS, Integrated Services Quality of Service IntServ QoS etc.), different access network technologies (e.g. wireless local area network WLAN, UMTS radio access network UTRAN, . . . ) and may be under control of different operators. The network has mobility support, i.e. a Mobile Node (MN) can move between those networks without breaking connections on higher layers (e.g. Transmission Control Protocol TCP). This process is called “handover” and can e.g. be provided by Mobile IP on layer 3. However, which mechanism is used for this purpose has no effect on this invention. A handover process comprises various tasks like authentication and authorization at the new network, relocation of radio link and IP session, establishing QoS states in the network etc. To support seamless handover, the performance of the handover has to be improved, i.e. the handover delay has to be reduced. To this end, context transfer can be applied. “Context transfer” is a term for transferring MN-related context or states (e.g. for QoS, header compression, AAA etc) from one network entity (e.g. Access Router AR) to another, so that the MN does not have to re-establish the states in the new network entity from scratch after the handover. The “seamoby” working group in the Internet Engineering Task Force (IETF) has developed a layer 3 protocol called Context Transfer Protocol (CTP) to enable authorized context transfer between ARs in IP networks (J. Loughney, M. Nakhjiri, C. Perkins, R. Koodli, “Context Transfer Protocol”, IETF Internet Draft draft-ietf-seamoby-ctp-11.txt, August 2004). It supports proactive or predictive context transfer, i.e. transferring the context from the current AR to the next AR before the handover is performed, as well as reactive context transfer, i.e. transferring the context from the previous AR to the current AR after the handover took place. The context transfer can be triggered by the mobile node, the previous AR or the next AR, respectively. CTP defines various messages: Context Transfer Request (CT-Req), Context Transfer Data (CTD), Context Transfer Data Reply (CTDR), Context Transfer Activate Request (CTAR), Context Transfer Activate Acknowledge (CTAA), and Context Transfer Cancel (CTC). These messages are exchanged between mobile node, previous AR and next AR. CTP assumes that MN and AR1 share a key for authorization purposes. FIG. 1 shows the signalling flow for a proactive context transfer with CTP. AR1 102 and AR2 103 belong to different networks 104 and 105 . After determining the IP address of AR2 103 (also called target or next AR/nAR) in S 106 , e.g. with support of the CARD protocol (see below), the MN 101 sends a CTAR message to AR1 102 (also called source or previous AR/pAR) in S 107 which contains the IP address of AR2, the IP address of the MN, a sequence number (SN) to match acknowledgements to requests, an authorization token and the types of context to be transferred. The authorization token is calculated by MN using a hash function and a key that is shared with AR1. AR1 verifies the token and, if successful, transfers the context data in S 108 together with the shared key to AR2 using the CTD message. AR2 can acknowledge the receipt with a CTDR message in S 109 . After the handover, the MN sends a CTAR message to AR2 in S 110 , which then again verifies the authorization token and installs the context in case of successful verification. Note that the message contains the IP address of pAR and the MN at the time it was attached to the pAR. Finally, AR2 can inform MN in S 111 about the status of the context transfer by sending a CTAA message. FIG. 2 shows the signalling flow in ease of a reactive context transfer. The procedure is similar, but in this case MN/UE 101 first sends a CTAR message to AR2 103 in S 201 . Thereafter AR2 requests the context from AR1 in S 202 using a CTR message. In S 203 AR2 receives context data and shared key from AR1 102 . Again, AR2 can send a CTAA message to MN/UE 101 in S 204 and acknowledge the receipt with a CTDR message sent to AR1 in S 205 . CTP is designed for AR-to-AR context transfer only. Heterogeneous networks or other source/target entities are not considered. In case of an inter-domain handover, additional problems arise that are not addressed by CTP as, e.g., different representation of context in source and target network, the need for potentially many inter-domain security associations (SAs) in order to secure the context transfer path or the automatic establishment of those SAs. Consequently a method is needed for context transfer in heterogeneous networks. The seamoby working group developed another protocol, the Candidate Access Router Discovery (CARD) protocol (M. Liebsch, A. Singh, H. Chaskar, D. Funato, E. Shim, “Candidate Access Router Discovery”, IETF Internet Draft draft-ietf-seamoby-card-protocol-08.txt, September 2004). CARD has mainly two tasks: Determining the layer 3 identifiers (IP addresses) of the CARs given that the mobile node has obtained layer 2 addresses of the corresponding candidate access points, e.g. by receiving beacons from them; and Discovering the capabilities of those CARs to assist the mobile node in determining the target AR. The protocol can be used to support the determination of the target AR for a predictive context transfer using CTP. The layer 3 identifiers of neighbouring ARs can be determined from the layer 2 identifiers discovered by the mobile node from received beacons using a centralized or a distributed approach. With the centralized approach, a CARD server performs reverse address resolution from layer 2 identifiers. With the distributed approach, information received from mobile nodes during handovers is used to establish a distributed address resolution cache. After the current AR discovered the layer 3 identifier of CARs, it can request information about related capabilities from them and give this information to the MN. IEEE 802.11f (“Trial-Use Recommended Practice for Multi-Vendor Access Point Interoperability via an Inter-Access Point Protocol Across Distribution Systems Supporting IEEE 802.11 Operation”, IEEE Computer Society, IEEE Std 802.11F-2003, July 2003) defines a layer 2 context transfer scheme (mainly for security-related context) to decrease the layer 2 handover delay when reauthenticating and reassociating with a new access point. Therefore, the old and the new access point (AP) exchange IAPP-MOVE or IAPP-CACHE packets for a reactive or proactive context transfer, respectively. In case of a proactive context transfer, APs construct and maintain so-called neighbour graphs based on information received in reassociation-request or IAPP-MOVE.request frames. Neighbour graphs are used to determine candidate APs for the context transfer. 802.11 is designed for AP-to-AP context transfer only. Heterogeneous networks or other source/target entities are not considered. Consequently there is a need for a method for context transfer in heterogeneous networks. The overall goal of performing context transfer is to reduce the handover delay to support seamless mobility. Thus, the context transfer should be as fast as possible. To achieve this goal, the context transfer should be done in a proactive manner if possible and the context transfer path should be as short as possible. Reactive context transfer should be supported as well in case a handover cannot be predicted early enough. To provide protection against malicious nodes, the transfer must also be secure (per-packet authentication, integrity protection and confidentiality), which requires IPsec security associations (SA) between the source and target entities of the context transfer. An SA usually involves authentication and encryption in the information transfer. All those features are provided by CTP for intra-domain handovers. However, in case of inter-domain handovers in a heterogeneous environment such as a 4G network, additional requirements must be considered: multiple source/target entities of different kind may be involved, e.g. AAA servers and ARs. Furthermore, source and target network may use different radio and network technologies, e.g., DiffServ and IntServ Qos technology, which may require additional means such as translation of context to a representation which the target network understands. Finally, managing inter-domain SA causes effort, such as key exchange and distribution or may even require manual intervention. Thus, the number of inter-domain SAs should be minimized. Furthermore, previous approaches utilizing management nodes for context transfer do not always use the best path for context transfer, which leads to sub-optimal performance. WO03052962 describes a system for storing inactive context in a central database (one per administrative domain) and active context in a local context directory located in ARs. A protocol for transferring context between ARs is presented as well. A so-called memory transfer agent is used to transfer only active feature context, i.e. context of active or “in progress”-microflows, from one AR to another. This document supports only a proactive context transfer scheme. The central entity comprises a Main Contact Database (MCD), a Memory Gateway External (MGE) as an interface to other domains and a Memory Gateway local (MGL) as interface to the local ARs. The AR contains a Local Context Directory (LCD), which maintains a list of active contexts of all mobile nodes associated with that AR, a Memory Tranfer Agent (MTA), which is responsible for transferring context between LCDs of different ARs, and a Context Transfer Agent (CTA), which establishes contact to a target AR. When a new microflow becomes active, context is transferred from the MCD via the MGL to the LCD of the current AR. The context transfer is triggered by the mobile node, which sends an ICMP message to the current AR. This message contains a list of target ARs and their preference level. Subsequently, the current AR requests a transfer of the active contexts of this mobile node to the target AR. The target AR may also request additional context from the MCD. In case a handover between different administrative domains is triggered, the context transfer between ARs takes place as usual, but additionally inactive context is transferred between the MCDs of both domains. WO03052962 like CTP only supports AR-to-AR context transfer, but additionally stores inactive context in a main database. It shifts complexity from the ARs to policy servers in the network, e.g. to perform candidate access router discovery. The context transfer path in case of an inter-domain transfer is always AR1.fwdarw.PS1.fwdarw.AR2.fwdarw.PS2. Thus, each policy server needs (inter-domain) SAs to all edge ARs of adjacent networks, which may lead to scalability problems. Furthermore, a difference of context representation in source and target network leads to incomplete context transfers since no context translation is supported. In WO03091900, another system is described for proactive transfer of application specific (as opposed to network specific) context between ARs of different administrative domains and access networks. The application specific context is created by the mobile node beforehand. The new AR evaluates the application context and, if necessary, discovers network entities in its domain that support the desired application. For example, the mobile node receives a video stream over a WLAN access network. Before it hands off to a cellular network, it constructs application-specific context containing information about the video stream (bit rate, format etc.) and sends it to the current AR. The AR transfers the context to the next AR of the cellular network, which can then discover and set up a ping-pong tunnel to a proxy server, transcoding the video stream to a lower bit-rate stream. WO03091900 handles registering and transfer of application-specific functional requirements, e.g. to provide application proxies at the new point of attachment. In WO02092314, a system is presented that deals with discovering appropriate candidate ARs. It includes a method for detecting, based on the application specific context on the mobile node, a first set of capabilities of a network node that facilitates maintaining an IP session, and a method for querying from a potential next network node capability information and determining if this node is able to fulfil the requirements. The query can be done by the mobile node or the current AR. WO02092314 focuses on corresponding candidate access router discovery mechanisms and does not provide methods for inter-domain context transfer. The method presented in WO03049377 utilizes the policy server, a central entity per administrative domain. This server is responsible for selecting possible target ARs. In the first step, all ARs report their capabilities to the policy server. When the mobile node receives information about another AR, it sends identity information, e.g. the layer 2 identifier of the access point, to the current AR which forwards it to the policy server of the current domain. In case of an inter-domain handover, the identifier and other information about the mobile node are sent to the policy server of the target domain. This server determines if it can serve the mobile node. If so, it computes a list of candidate ARs based on given full topology information and according to an algorithm that considers the mobile node's capabilities, the traffic load on the ARs and operator defined rules. The context transfer itself can be performed in a proactive or reactive manner. In the reactive case, the mobile node triggers the context transfer by sending a request message to the new AR. The context is then transferred from the previous AR to the corresponding policy server, which may add static context and may collect dynamic context from other network entities, and sends it to the current AR. In the proactive case, the request message is sent to the current AR and the context is transferred from the current AR over the corresponding policy server to the next AR. In both cases, the target AR additionally transfers the context to its policy server, which can then forward the context to other network entities, like security gateways. In the system described in WO2004070989, a so-called Core State Management Node (CSMN) is located in the core of the network, which stores, manipulates and forwards context to prevent the need for signalling between ARs. The CSMN can be co-located with an AAA server and may store state data itself or the location of the state if located in another network entity. Both, proactive and reactive context transfers are supported. The mobile node triggers the context transfer by sending a message to the current AR which includes identifiers of the mobile node and of the target AR as well as a region ID in case of a handover between regions. In case of a handover within the region of one CSMN, the previous AR transfers the state to the CSMN, which then stores the state. The next AR then retrieves the state from the CSMN. If a handover takes place between two regions, two CSMNs are involved in the context transfer. In the reactive case, the context is transferred from the previous AR to the corresponding CSMN, which stores the context. After receiving a trigger message from the mobile node, which includes an identifier of the previous region, the next AR can request the state from its CSMN after the handover, which retrieves the state from the CSMN of the previous region. In the proactive case, the context is transferred from the current AR to its CSMN, which stores it and forwards it to the target CSMN. After the handover, the target AR can retrieve the context from its CSMN. Message formats of the context transfer protocol are not defined. In WO2004070989, again, different context representations and source/target entities are not supported. Additionally, the AR in the new network first retrieves the context from the CSMN after the handover, even in case of a proactive context transfer. Moreover, the context is routed over the CSMNs in both cases, inter- and intra-domain handover. Both issues result in additional handover latency. Also, no protocol is defined for performing the context transfer. Protocols currently in discussion in IETF standardization cannot be re-used since they do not support the proposed architecture. In WO03092315 a system and method is proposed that performs candidate AR discovery in an external server element, e.g. an application server outside the operator's network. This server is provided with information identifying the AR currently serving the mobile node and the ARs which are within reach of the mobile node. The server then determines one or more target ARs. The capability information needed for the selection algorithm can be initially provided by the operator or dynamically obtained from the mobile node or by querying the ARs. For the latter two approaches, appropriate SAs between the application server and all ARs are needed since the server can be located outside the operator's network. The dynamic candidate access discovery works as follows: the mobile node sends the layer 2 and 3 identifiers of the current and previous AR/AP to the application server after the handover. Thus, the server can establish and maintain an L2-L3 address mapping table and knows which ARs/APs are adjacent. When another mobile node receives layer 2 beacons containing the identifier from adjacent access points, it sends this information to the application server, which then can derive the layer 3 identifier of the corresponding ARs from this information using the address mapping table established before. After knowing the layer 3 identifiers of candidate ARs, information about their capabilities can be requested either by the application server or by the mobile node. Finally, the target router selection can be performed either in the mobile node or in the application server. Furthermore, methods are described for registering application specific context of the mobile node at the application server, which can take care of relocating, e.g., a security gateway, a location server or a proxy. In case of an inter-domain handover, the application server in the old domain discovers respective network entities, e.g. a location server, in the new domain. WO03092315 only deals with candidate access router discovery. It does not provide solutions for the context transfer itself. None of the proposals utilizes the context transfer protocol that is currently standardized by the IETF and none of them deals with the efficient automatic establishment and cancellation of SAs. It is an object of the present invention to provide a method and an apparatus for context transfer in heterogeneous networks, which supports context transfer between access networks using different technologies and minimises the number of required inter-domain security associations. SUMMARY OF THE INVENTION The object can be achieved by utilizing at least one Context Transfer Manager (CTM) per domain that provides a single interface to other domains. This CTM is adapted to perform context translation, i.e. translation of context information into format and representation required by the target access network. In one aspect of the present invention, a method for context transfer to be executed in a context transfer manager of a heterogeneous mobile network comprising a plurality of access networks comprises the steps of a) collecting context information related to a mobile node from at least one source entity within a first access network; b) transmitting the collected context information to a context transfer manager within a second access network; c) receiving context information related to a mobile node from a context transfer manager within an access network different from the first access network; d) forwarding the context information received in step c) to at least one target entity within the first network; and e) before step b) and/or after step c), translating at least a part of the context information from a format supported in one access network to another format supported in another access network. In another aspect of the present invention, a computer-readable storage medium has stored thereon instruction, which, when executed on a context manager of a radio access network in a heterogeneous mobile network, cause the context manager to perform the method according to the first aspect. In still a further aspect of the present invention, a context manager for an access network within a heterogeneous mobile network comprises means for collecting context information related to a mobile node from at least one source entity within a first access network; means for transmitting the collected context information to a context transfer manager within a second access network; means for receiving context information related to a mobile node from a context transfer manager within an access network different from the first access network; means for forwarding the context information, received from the context transfer manager within the access network different from the first access network, to at least one target entity within the first network; and means for translating at least a part of the context information from a format supported in one access network to another format supported in another access network. In still another aspect of the present invention, a method to be executed in a heterogeneous mobile network comprising a plurality of access networks comprises the steps of the method according to the first aspect, executed in at least two context managers located in two different access networks of the mobile network, and the method further comprises the steps of f) sending from a mobile node a message to a first access router of the first access network, comprising information about the identity of the mobile node, information about an identity of a second access router, and information about types of context to be transferred; and g) forwarding said message from the access router to the context transfer manager in the first network prior to steps a) and b) being performed by said context transfer manager and steps c) and d) being performed in the context transfer manager of another access network to which said second access router belongs. In yet another aspect of the present invention, a method to be executed in a heterogeneous mobile network comprising a plurality of access networks comprises the steps of the method according to the first aspect, executed in at least two context managers located in two different access networks of the mobile network, and further comprises the steps of sending from a mobile node a message to an access router of the second access network, comprising information about the identity of the mobile node, information about an identity of an access router in the first access network, and information about types of context to be transferred; forwarding said message from the access router to the context transfer manager in the second network; and sending a message from the context transfer manager in the second access network to the context manager in the first access network, comprising information about the identity of the mobile node and about types of context to be transferred, thereby causing steps a) and b) to be performed by said context transfer manager of the first access network and steps c) and d) to be performed in the context transfer manager of the second access network. In still a further aspect of the present invention, a heterogeneous mobile network comprises at least one mobile node ( 101 ); and at least two access networks ( 104 , 105 ), wherein at least two of the access networks each comprise at least one context transfer manager ( 302 , 303 ) according to claim 10 and at least one access router ( 102 , 103 ). The utilization of dedicated management nodes (Context Transfer Manager, CTM) has many advantages. Those nodes can manage the context transfer and provide a single interface between two domains/access networks. If the context is routed over those nodes in case of inter-domain handovers, only one inter-domain SA is needed for context transfers between two domains. Additionally, the CTMs can perform further actions, like translating the context if the representation in both domains differs or triggering additional signalling, e.g. to reserve network resources for packet transmission related to the mobile host to which the context information belongs, to set up data tunnels in advance or establish an End-to-End QoS path in advance. This takes some burden from the ARs, eases the management of the network and may help operators hiding information about their network to other operators. In summary, the benefits of this invention are Support of inter-domain context transfer in heterogeneous networks including context translation and multiple source/target entities; Minimisation of the number of inter-domain SAs; Utilization of CTP, a protocol currently being standardized by the IETF; Selection and utilization of the best context transfer path depending on the type of handover (inter-/intra-domain); and early establishment and cancellation of SAs between CTMs. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings are incorporated into and form a part of the specification for the purpose of explaining the principles of the invention. The drawings are not to be understood as limiting the invention to only the illustrated and described examples of how the invention can be made and used. Further features and advantages will become apparent from the following and more particular description of the invention, as illustrated in the accompanying drawings, wherein FIG. 1 illustrates the signalling flow for proactive context transfer using CTP; FIG. 2 depicts the signalling flow for reactive context transfer using CTP; FIG. 3 shows context transfer directly between ARs (a) or over CTMs (b); FIG. 4 illustrates the signalling flow for proactive inter-domain context transfer using CTP and CTMs; FIG. 5 illustrates the signalling flow for reactive inter-domain context transfer using CTP and CTMs; FIG. 6 depicts a flow chart of procedures in a pAR in case of proactive context transfer; FIG. 7 depicts the signalling flow and beacon count state for early SA establishment and cancellation; FIG. 8 shows a flow chart with the steps of a method for early establishment and early cancellation of security associations between Context Transfer Managers; and FIG. 9 illustrates the basic structure of a server which can be used as Context Transfer Manager. DETAILED DESCRIPTION OF THE INVENTION The exemplary embodiments of the present invention will be described with reference to the figure drawings wherein like elements and structures are indicated by like reference numbers. In the following, the invention will be explained without loss of generality for the example of CTP. However, the invention can be applied to any protocols that communicate context from AR to AR and require an SA between both ARs, such as “Fast handovers for Mobile IPv6” (Rajeev Koodli, “Fast Handovers for Mobile IPv6”, IETF Internet Draft draft-ietf-mipshop-fast-mipv6-03.txt, October 2004). As mentioned above, the CTM architecture has advantages for inter-domain context transfer in heterogeneous networks, especially if a handover to another domain is possible between different ARs. CTMs provide a single interface to other domains and thus minimize the number of inter-domain SAs, can take care of context translation, context collection (from various entities, such as AAA server) and aggregation. FIG. 3 illustrates the difference between a direct context transfer between ARs and a context transfer over CTMs. Access Network AN1 104 comprises AR1 102 as well as other ARs 301 . AN2 105 comprises AR2 103 and further ARs 301 . A mobile node 101 can communicate with each of the networks. While communicating with AN1 over AR1, the MN 101 might move such that it enters the service area of AN2 and is about to leave the service area of AN1. A handover is necessary, during which context for running applications has to be transferred from AR1 to AR2. In FIG. 3 a the context is directly transferred from AR1 to AR2. An SA is required between the ARs across the boundaries of the domains AN1 and AN2. At the same time more such SAs might exists between other ARs 301 related to services of further mobile nodes. In FIG. 3 b one Context Transfer Manager CTM 302 , 303 per domain handles the context transfer. Thus only one SA is required between the ANs 104 and 105 for all instances of context transfer going on. However, CTP does not support the utilization of CTMs. The problem of routing the context (in case of CTP the CTD messages) over dedicated Context Transfer Management (CTM) entities could be solved by using IP-layer routing. A drawback of this approach is that the underlying routing infrastructure is affected and context aggregation is not possible. Furthermore, the router alert option would be needed in this case to enable the CTMs to manipulate the context on the fly. Therefore application layer routing is used: The source AR 102 forwards the CTAR message to the source CTM 302 , which then requests the context from the source AR and various source entities, such as AAAI (Authentication, Authorization, and Accounting entity 1) 304 . After manipulating the context, the CTM 302 then forwards the context in an aggregated. CTD message to the target CTM 303 on application layer, which in turn may manipulate the context. Finally, it forwards the context to the respective target entities, such as AAA2 305 and AR2 103 . The source CTM 302 knows the target AR's IP address from the received CTAR message. The source CTM is required to provide the target AR's IP address to the target CTM 303 , so that the target CTM can forward the context to the target AR. This is realized by adding a new field containing the target AR's IP address to the CTD message. FIG. 4 shows the signalling flow for a proactive inter-domain context transfer using CTP and CTMs. At S 400 , CTM1 302 and CTM2 303 exchange information about their capabilities and about capabilities of their access networks AN1 104 and AN2 105 . This information may comprise information about supported context formats. Other than in FIG. 1 , AR1 102 forwards the CTAR message received in S 403 to CTM1 302 in S 404 , which collects the context from all source entities 102 , 401 in S 405 and transfers the CTD message to CTM2 303 in S 405 . Note that the CTD message contains an additional field, the target AR's 103 IP address. In addition, if AN1 and AN2 employ different technologies in their radio interface or for packet transport in the core or aggregation network, at least a part of the context is translated in a step S 412 from a format supported in AN1 into a different format, supported in AN2. This may be done in CTM1 before sending the CTD message, or in CTM2 subsequent to receiving this message. CTM2 in turn forwards the context to the corresponding target entities 103 , 402 , in step S 407 which it determines based on the type of context. In S 408 CTM2 303 can. acknowledge the receipt of the CTD message by sending a CTDR message to CTM1 302 . After the handover, the MN sends a CTAR message to AR2 in S 409 . AR2 forwards the message to CTM2 in S 410 , which then again verifies the authorization token and informs the target entities to install the context in case of successful verification. Alternatively, CTM2 may send the context to the target entities only after successful verification of the token. In this case the target entities can install the context immediately. Note that the message contains the IP address of pAR and the MN at the time it was attached to the pAR. Finally, AR2 can inform MN in S 411 about the status of the context transfer by sending a CTAA message. FIG. 5 shows the corresponding signalling flow for a reactive context transfer. In this case, the CTAR message is sent in S 501 from MN 101 to AR2 103 which forwards it to CTM2 303 in S 502 . In S 503 , CTM2 303 requests the context transfer from CTM1 302 with a CT-Req message specifying the previous IP address of MN 101 (while registered to AN1), a sequence number (SN) to match acknowledgements to requests, an authorization token and the types of context to be transferred. In S 504 CTM1 302 collects the context from all source entities 102 , 401 and transfers the CTD message to CTM2 303 in S 505 . Note that an additional field for the target AR's IP address in the CTD message is not required in this case, since the target CTM receives the CTAR message from the MN, which contains the target AR's IP address. In S 506 CTM2 forwards the context to the corresponding target entities 103 , 402 which it determines based on the type of context. Again, CTM2 303 can acknowledge the receipt of the CTD message by sending a CTDR message to CTM1 302 in S 507 and inform MN 101 in S 508 about the status of the context transfer by sending a CTAA message. As with the proactive context transfer, at least a part of the context may be translated in S 412 to a different format as required, in CTM1 before sending it with the CTD message, or in CTM 2 subsequent to receipt of this message. The process described so far always routes the context over the CTMs. This is desired for inter-domain handovers, but in case of intra-domain handovers this is not necessary and results in worse performance, since the context transfer path is longer. To prevent this, the CT path is selected depending on the type of handover. The handover performance is improved by handling intra- and inter-domain handover differently. The path over the CTMs should be used for inter-domain handover to minimize the number of inter-domain SAs and to enable context translation etc. In case of intra-domain handover the AR-to-AR CT path should be used instead, since the CTMs are not required and the direct path between the ARs is shorter. Which type of handover (intra- or inter-domain) is existent is determined in parts by the source AR and in parts by the source CTM. The source AR may transfer the context itself, if an SA exists to the target AR. Otherwise it forwards the CTAR message to the source CTM, which determines by itself if the target AR's IP address is part of its domain. It is therefore assumed that CTMs know the IP addresses or the address space of all ARs of their domain. In case the target AR is not in the same domain, the CTM concludes that an inter-domain handover is existent and transfers the context itself. Otherwise an intra-domain handover is assumed. In this case the CTM may send the CTAR message back to the source AR, which then can establish an SA to the target AR to transfer the context. The proposed solution requires no modification to CTP's message formats, but a modification of AR's state machine. FIG. 6 shows a flow chart of this procedure taking place in pAR in case of a proactive context transfer. After receiving the CTAR message in S 601 , the AR validates the authorization token in S 602 . If the validation fails, the AR informs the MN in S 603 by sending a CTAA message containing the error code. Otherwise, the pAR checks in S 604 whether an SA exists to the target AR. If this is the case (case 1), an intra-domain handover is assumed and the pAR may transfer the context in S 605 using a CTD message. The transfer is repeated in S 605 and S 606 until the target AR acknowledges the receipt with a CTDR message (optional). The process described so far is exactly the same as the process of unmodified CTP. If S 604 detects that no SA to the nAR exists, CTP would normally cancel the context transfer. With the modifications proposed in this invention, pAR checks in S 607 whether the CTAR message was received from MN or CTM. This can be determined, e.g., based on the IP source address or a new flag in the CTAR message. If it has been received from the CTM, it is assumed that an intra-domain context transfer is required, and a SA from the source pAR to the target nAR is established in S 609 for this purpose. If the CTAR message has been received from the MN (case 2), the pAR assumes an inter-domain handover and forwards the CTAR message to its CTM in S 608 . The CTM knows the IP addresses or the address space of all ARs in its domain and thus can decide if an intra- or inter-domain handover is existent. In the latter case, it performs the context transfer itself: it collects the context from pAR and other entities using CT-req messages and sends an aggregated CTD message to the target CTM. The CTD message contains a new field for the target AR's IP address (see step S 406 in FIG. 4 ). It is assumed that the address of the target CTM is known to the source CTM, e.g. by deriving it from the target AR's IP address. Furthermore, it is assumed that an SA exists between both CTMs (How the SA can automatically be established is described below). When the target CTM receives the CTD message, it forwards the individual contexts to the corresponding target entities using CTD messages. It is assumed that the IP address of a target entity corresponding to a specific type of context (such as IP address of the AAA server corresponding to AAA context) is known to the target CTM, e.g. by pre-configuration or by additional signalling e.g. to a database. If the CTM decides that an intra-domain handover is existent, it may send the CTAR message back to the pAR, which then establishes an SA to the nAR (S 609 ) and transfers the context (S 605 ) as the unmodified CTP would do (case 3). The described solution can analogously applied to the reactive case as well. The invention can analogously be applied to a hierarchy of CTMs. In case a network is multi-homed, a path other than the direct path between source and target network may be topologically shorter in certain situations or may have higher capacity, e.g. the path over the home networks if source and target network are both foreign networks with a low-bandwidth interconnection. In this ease the performance is increased if the CTM of the source network routes the context over the home network to the target CTM. For optimal performance, the context transfer duration of the alternative paths can be measured by the source CTM, either by sending explicit probe messages or passively using the messages of an ongoing context transfer. This information can then be used to select the best path for the next context transfer. In the following, a mechanism for early establishment and cancellation of SAs between CTMs will be proposed. Candidate CTMs are determined based on the number of received broadcast messages containing layer 2 identifiers. These messages will in the following be called “beacons”. The basic idea is to utilize information from layer 2 beacons received by the MN from APs of adjacent domains to trigger the early establishment and cancellation of SAs between CTMs. The MN either counts these beacons itself or periodically sends messages to the network, which counts the beacons on behalf of the MN. The count is done per time unit, which means that it is essentially a rate and that it is decreased if no beacons are received anymore. The beacon count state is maintained per AP's MAC address. If the signal strength of the MN indicates that a handover may be pending and a threshold A has been exceeded, the CARD protocol is started for the corresponding APs. Furthermore, the CARD reply message triggers the establishment of an SA between the corresponding CTMs. If a second threshold B is exceeded, the source CTM cancels all SAs except of the one corresponding to the AP, whose beacon count exceeded threshold B. Since only unused SAs may be cancelled, CTMs need to maintain some state information about the progress of a specific context transfer. Using the proposed threshold comparison, only the most probable SAs remain and resources are not wasted. Moreover, a context transfer can start immediately without additional handover latency resulting from the establishment of an SA. FIG. 7 illustrates this process. The MN 101 is associated in S 704 to AP1 102 in Access Network 1 (AN1) 104 . It receives beacons from AP2 103 and AP3 702 in AN2 105 and AN3 703 , respectively in S 705 . Since the beacon count for both APs exceeded threshold A in counting step S 706 , an SA is established between CTM1 and CTM2 and CTM1 and CTM3, respectively in S 707 . After the beacon count for AP2 exceeded threshold B in counting step S 708 , the SA to AN3 is cancelled in S 709 . Subsequently, the SA already exists when a context transfer is performed to AN2 in S 710 and when the actual handover occurs in S 711 , the context is already installed in the respective network entities in AN2. Note, that in the current IEEE 802.11 specification, beacons of APs other than the one the STA is associated with cannot be received, if they send beacons on a different channel/frequency. However, other wireless technologies or future specifications of IEEE 802.11 may support this. Also note that in case APs send beacons in different time intervals, the entity responsible for comparing the beacon counts must be aware of the configured interval at a specific AP to be able to make a fair comparison, e.g. using normalization. The steps of this method are depicted in more detail in the flow chart in FIG. 8 . In S 704 , the MN/UE is associated to AP1. While it is associated with AP1, the MN/UE continuously or intermittently receives beacons from other APs (or ARs) in S 705 . For the next two steps there exist two alternatives. In the first alternative the MN/UE sends messages about received beacons in S 801 to AP1 which may forward them to CTM1. In S 802 either AP1 or CTM1 counts received beacons per time unit for each APi separately. This step may also comprise the normalisation with regard to the rate of beacon transmissions of different APs, as described above. In the second alternative the MN does the counting in S 803 and sends the results to the AP1 in S 804 which, again, may forward them to CTM1. Also here, the counting step may comprise a normalisation operation. Alternatively the normalisation may be done in the AP or CTM. The following steps may be executed in the AP1 or CTM1. However, all steps apart from S 709 and S 707 could also be executed in the MN. In this case the MN would send instead of step S 801 or step S 804 messages to the CTM causing the CTM to perform steps S 707 and/or S 709 . In S 805 a specific APi different from AP1 is selected. For this APi it is checked in S 806 whether its (normalised) beacon count per time unit exceeds a predetermined limit A. If this is not the case, a possibly existing security association (SA) from CTM1 to CTMi in the radio access domain ANi of APi is cancelled with step S 709 , unless it is currently used and unless use is predicted for another mobile node. Then, the method continues in S 810 with checking whether there are more APs to be treated. If so, a next APi is selected in S 811 and steps from S 806 are repeated for this APi. If all APs have been treated in this instance of steps S 805 to S 811 , the method returns to the reception of beacons (S 705 ). Referring back to S 806 , if the (normalised) beacon count per time unit of APi exceeds limit A, it is next checked in S 808 whether the (normalised) beacon count per time unit of any other APj exceeds the limit B described above. Alternatively another limit value C different from the value of B may be chosen here. If the condition of S 808 is not fulfilled, the method concludes that APi is a likely handover candidate, and a SA is established in S 707 , if not yet existing, from CTM1 to CTMi in ANi to serve for the context transfer in the case of a handover. This way, time needed to complete the handover is reduced. Referring back to S 808 , if at least one APj is found with a (normalised) beacon count per time unit exceeding limit B (or C, respectively), it is concluded that there is another strong handover candidate. In the case that the limit B is defined as a fixed value independent of the (normalised) beacon count per time unit of APi, it is checked in S 809 whether also the (normalised) beacon count per time unit of APi exceeds limit B. In this case it is determined that both APi and APj are strong handover candidates and the method continues in step S 707 with establishing an SA. from CTM1 to CTMi, if it does not exist already. In the case that the (normalised) beacon count per time unit of APi does not exceed limit B, it is concluded that APj is a much stronger handover candidate than APi and that any existing SA from CTM1 to CTMi will not be needed in the next future. Therefore such a SA is cancelled in S 709 if it exists, unless it is currently used and unless use is predicted for another mobile node. This has the advantage that signalling overhead, requiring processing power in the CTMs and causing network load, is reduced. Referring back to the “Yes” output of S 808 , in the case that limit B is defined at a certain margin above the (normalised) beacon count per time unit of APi, checking step S 809 is unnecessary and the method continues directly with S 709 . In any case the method continues thereafter with S 810 , checking whether there is any other APi to be treated, as described above. In one alternative, the limit of S 809 may be chosen as a value D different from the limit B (or C, respectively) of S 808 . Choosing limits B, C and D differently provides the possibility to adjust the average living time of SAs for an optimum compromise between handover acceleration and signalling overhead reduction. Further threshold values may be defined to trigger more actions like context transfer and proactive establishment of data tunnels, depending on the likelihood of a handover to any access point or access router APi. Context transfer manager 302 , 303 is a logic entity which carries out the functions described above. It may be physically located in a dedicated server, within a network node such as a gateway or within other network entities like AAA server 304 , 305 . FIG. 9 shows an exemplary structure of a server 900 which can be used as a Context Transfer Manager (CTM) as described above. It comprises at least one network interface 902 , a central processing unit 901 and a non-volatile data storage 903 . CPU 901 comprises a processor or controller and working memory RAM. It is configured to perform the tasks of the CTM as described in detail above. Tasks of the CTM in the method described above can be implemented in hardware logic or in software executed on the processor or controller of the CPU. Also mixed implementations are possible. Programs comprising instructions which cause the server 900 to perform steps of the method described above may be stored in non-volatile memory 903 which may be a magnetic hard disk, optical disk, magnetic tape or non-volatile semiconductor memory like flash memory. Server 900 may further comprise other units like keyboard, display or more network interfaces, which are not requied for the described tasks of the CTM and therefore optional. Server 900 may be co-located with a network node or realised in a separate entity.

A method and apparatus for improved context transfer in heterogeneous networks is presented. Context information is collected from source entities in a first access network by a context transfer manager and transmitted to a context transfer manager of a second access network which forwards the context information to target entities therein. In one of the context transfer managers at least a part of the context information is translated from a format supported in the first access network to another format supported in the second access network. The method may be carried out proactively preceding a handover or reactively following a handover. In one embodiment, context transfer within one access domain is performed directly between access routers, whereas context transfer between different access domains is performed via the context managers. In another embodiment, beacons from access points are counted in order to determine candidates for a pending handover.

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a divisional of U.S. patent application Ser. No. 09/635,385, filed Aug. 9, 2000, now U.S. Pat. No. 6,495,600, which is a divisional of U.S. patent application Ser. No. 09/189,698, filed Nov. 10, 1998, now U.S. Pat. No. 6,225,353, which is a divisional of U.S. patent application Ser. No. 08/858,011, filed May 16, 1997, now U.S. Pat. No. 5,869,535, which is a continuation-in-part application of U.S. patent application Ser. No. 08/407,756, filed Mar. 21, 1995, now U.S. Pat. No. 5,658,947. This invention was made with government support under U01 CA52956 awarded by the National Cancer Institute. The government has certain rights in the invention. FIELD OF THE INVENTION This invention relates to compositions and methods of selectively inhibiting tumors and, more particularly, to treating a malignant melanoma using plant-derived compounds and derivatives thereof. BACKGROUND OF THE INVENTION Over the past four decades the incidence of melanoma has been increasing at a higher rate than any other type of cancer. It is now theorized that one in 90 American Caucasians will develop malignant melanoma in their lifetime. While an increasing proportion of melanomas are diagnosed sufficiently early to respond to surgical treatment and achieve a greater than 90% ten-year survival rate, it is estimated that nearly 7,000 individuals suffering from metastatic melanoma will die in the United States this year. For patients with metastatic melanoma not amenable to surgical extirpation, treatment options are limited. 5-(3,3-Dimethyl-1-triazenyl)-1-H-imidazole-4-carboxamide (dacarbazine, DTIC) is the most efficacious single chemotherapeutic agent for melanoma having an overall response rate of 24%. But the duration of response to DTIC is generally quite poor. Combination therapy with other synthetic and recombinant agents, including N,N′-bis(2-chloroethyl)-N-nitrosurea (carmustine, BCNU), cisplatin, tamoxifen, interferon-alpha (INF-α) and interleukin-2 (IL-2), has a higher response rate (e.g., 30-50%) in some trials, but a durable complete response rate is uncommon and toxicity is increased. Sequential chemotherapy has promise, but, clearly, current treatment options for individuals suffering from metastatic melanoma are unsatisfactory. Various drugs derived from natural products, such as adriamycin (doxorubicin) derivatives, bleomycin, etoposide, and vincristine, and their derivatives, have been tested for efficacy against melanoma either as single agents or in combination therapy. However, similar to the synthetic and recombinant compounds, these compounds exhibit low response rates, transient complete responses, and high toxicities. Nonetheless, as demonstrated by known and presently-used cancer chemotherapeutic agents, plant-derived natural products are a proven source of effective drugs. Two such useful natural product drugs are paclitaxel (taxol) and camptothecin. Paclitaxel originally derived from the bark of the Pacific yew tree Taxus brevifolia Nutt. (Taxaceae), currently is used for the treatment of refractory or residual ovarian cancer. More recently, clinical trials have been performed to investigate the possible role of paclitaxel in the treatment of metastatic melanoma. As a single agent, taxol displays activity comparable to cisplatin and IL-2. Taxol functions by a unique mode of action, and promotes the polymerization of tubulin. Thus, the antitumor response mediated by taxol is due to its antimitotic activity. The second drug of prominence, camptothecin, was isolated from the stem bark of a Chinese tree, Camptotheca acuminata Decaisne (Nyssaceae). Camptothecin also functions by a novel mechanism of action, i.e., the inhibition of topoisomerase I. Phase II trials of a water-soluble camptothecin pro-drug analog, Irinotican (CPT-11), have been completed in Japan against a variety of tumors with response rates ranging from 0% (lymphoma) to 50% (small cell lung). Topotecan, another water-soluble camptothecin analog, currently is undergoing Phase II clinical trials in the United States. Previous antitumor data from various animal models utilizing betulinic acid have been extremely variable and apparently inconsistent. For example, betulinic acid was reported to demonstrate dose-dependent activity against the Walker 256 murine carcinosarcoma tumor system at dose levels of 300 and 500 mg/kg (milligrams per kilogram) body weight. In contrast, a subsequent report indicated the compound was inactive in the Walker 256 (400 mg/kg) and in the L1210 murine lymphocytic leukemia (200 mg/kg) models. Tests conducted at the National Cancer Institute confirmed these negative data. Similarly, antitumor activity of betulinic acid in the P-388 murine lymphocyte test system has been suggested. However, activity was not supported by tests conducted by the National Cancer Institute. More recently, betulinic acid was shown to block phorbol ester-induced inflammation and epidermal ornithine decarboxylase accumulation in the mouse ear model. Consistent with these observations, the carcinogenic response in the two-stage mouse skin model was inhibited. Thus, some weak indications of antitumor activity by betulinic acid have been reported, but, until the present invention, no previous reports or data suggested that betulinic acid was useful for the selective control or treatment of human melanoma. Furthermore, to date, no information has been published with respect to the selective activity of derivatives of betulinic acid against melanoma cells. SUMMARY OF THE INVENTION The present invention is directed to a method and composition for preventing or inhibiting tumor growth. The active compound is betulinic acid or a derivative of betulinic acid. The betulinic acid is isolated by a method comprising the steps of preparing an extract from the stem bark of Ziziphus mauritiana and isolating the betulinic acid. Alternatively, betulin can be isolated from the extract and used as precursor for betulinic acid, which is prepared from betulin by a series of synthetic steps. The betulinic acid can be isolated from the extract by mediating a selective cytotoxic profile against human melanoma in a subject panel of human cancer cell lines, conducting a bioassay-directed fractionation based on the profile of biological activity using cultured human melanoma cells (MEL-2) as the monitor, and obtaining betulinic acid therefrom as the active compound. The resulting betulinic acid can be used to prevent or inhibit tumor growth, or can be converted to a derivative to prevent or inhibit tumor growth. An important aspect of the present invention, therefore, is to provide a method and composition for preventing or inhibiting tumor growth and, particularly, for preventing or inhibiting the growth of melanoma using a natural product-derived compound, or a derivative thereof. Another aspect of the present invention is to provide a treatment method using betulinic acid to prevent the growth or spread of cancerous cells, wherein the betulinic acid, or a derivative thereof, is applied in a topical preparation. Another aspect of the present invention is to overcome the problem of high mammalian toxicity associated with synthetic anticancer agents by using a natural product-derived compound, e.g., betulinic acid or a derivative thereof. Still another aspect of the present invention is to overcome the problem of insufficient availability associated with synthetic anticancer agents by utilizing readily available, and naturally occurring betulinic acid, or a derivative thereof. Yet another aspect of the present invention is to prepare derivatives of betulinic acid that have a highly selective activity against melanoma cells, and that have physical properties that make the derivatives easier to incorporate into topical preparations useful for the prevention or inhibition of melanoma cell growth. These and other aspects of the present invention will become apparent from the following description of the invention, which are intended to limit neither the spirit or scope of the invention but are only offered as illustrations of the preferred embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plot of mean tumor volume (in cubic centimeters (cm 3 )) vs. time for nonestablished MEL-2 tumors in control mice and mice treated with increasing dosages of betulinic acid; FIG. 2 is a plot of mean tumor volume (in cm 3 ) vs. time for established MEL-2 tumors in control mice and mice treated with DTIC or betulinic acid; FIG. 3(A) is a plot of the 50 Kbp (kilobase pairs) band as % total DNA v. time for treatment of MEL-2 cells with 2 μg/ml (micrograms per milliliter) betulinic acid; FIG. 3(B) is a plot of the 50 Kbp band as % total DNA versus concentration of betulinic acid (μg/ml); and FIGS. 4 and 5 are plots of mean tumor volume (cm 3 ) vs. time for established and nonestablished MEL-1 tumors in control mice and mice treated with increasing doses of betulinic acid. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Betulinic acid, 3β-hydroxy-lup-20(29)-ene-28-oic acid, is a natural product isolated from several genus of higher plants. Through a bioassay-directed fractionation of the stem bark of Ziziphus mauritiana Lam. (Rhamnaceae), betulinic acid, a pentacyclic triterpene, was isolated as an active compound that showed a selective cytotoxicity against cultured human melanoma cells. The cell lines evaluated for cytotoxicity were A431 (squamous), BC-1 (breast), COL-2 (colon), HT-1080 (sarcoma), KB (human oral epidermoid carcinoma), LNCaP (prostate), LU-1 (lung), U373 (glioma), and MEL-1, -2, -3, and -4 (melanoma). Betulinic acid was found to be an excellent antitumor compound against human melanoma due to its unique in vitro and in vivo cytotoxicity profile. Betulinic acid has shown a strong selective antitumor activity against melanoma by induction of apoptosis. The selective cytotoxicity of betulinic acid, and its lack of toxicity toward normal cells, afford a favorable therapeutic index. In addition, betulinic acid has been reported to have an anti-HIV activity. The bark of white birch, Betula alba , contains betulin (up to about 25%), lup-20(29)-ene-3β,28-diol, and betulinic acid (0.025%), but it is difficult to isolate a sufficient quantity of betulinic acid to perform an extensive bioassay. It has been found that a quantity of betulinic acid could be provided from betulin through a simple synthetic approach. A number of multi-step synthetic conversions of betulin to betulinic acid have been reported, but these synthetic sequences suffer from a low overall yield. A concise two-step conversion of betulin to betulinic acid, in good yield, has been reported in Synthetic Communications, 27(9), pp. 1607-1612 (1997). As shown in Table 1, in vitro growth of MEL-2 cells was inhibited by betulinic acid, i.e., an ED 50 value of about 2 μg/ml. However, none of the other cancer cell lines tested was affected by betulinic acid (i.e., ED 50 values of greater than 20 μg/ml). Such clearly defined cell-type specificity demonstrated by betulinic acid is both new and unexpected. For example, as illustrated in Table 1, other known antitumor agents, such as paclitaxel, camptothecin, ellipticine, homoharringtonine, mithramycin A, podopyllotoxin, vinblastine and vincristine, demonstrated relatively intense, nonselective cytotoxic activity with no discernible cell-type selectivity. Moreover, the cytotoxic response mediated by betulinic acid is not exclusively limited to the MEL-2 melanoma cell line. Dose-response studies performed with additional human melanoma cell lines, designated MEL-1, MEL-3 and MEL-4, demonstrated ED 50 values of 1.1, 3.3 and 4.8 μg/ml, respectively. In the following Table 1, the extracted betulinic acid and the other pure compounds were tested for cycotoxity against the following cultured human cell lines: A431 (squamous cells), BC-1 (breast), COL-2 (colon), HT-1080 (sarcoma), KB (human oral epidermoid carcinoma), LNCaP (prostate), LU-1 (lung), MEL-2 (melanoma), U373 (glioma) and ZR-75-1 (breast). TABLE 1 Cytotoxic Activity Profile of the Crude Ethyl Acetate Extract Obtained from Ziziphus mauritiana , Betulinic acid, Other Antineoplastic Agents ED 50 (μg/ml) Compound A431 BC-1 COL-2 HT-1080 KB LNCaP LU-1 MEL-2 U373 ZR 75-1 Ziziphus mauritiana >20 >20 >20 9.5 >20 >20 5.2 3.7 >20 15.8 crude extract Betulinic acid >20 >20 >20 >20 >20 >20 >20 2.0 >20 >20 Taxol 0.00 0.02 0.02 0.00 0.02 0.02 0.00 0.06 0.008 0.02 Camptothecin 0.00 0.07 0.005 0.01 0.00 0.006 0.00 0.02 0.000 0.001 Ellipticine 0.5 0.2 0.3 1.8 0.04 0.8 0.02 0.9 1.6 0.9 Homoharringtonine 0.02 0.03 0.1 0.01 0.00 0.03 0.03 0.04 0.2 0.06 Mithramycin A 0.09 0.3 0.06 1.5 0.09 0.05 0.2 1.2 0.04 0.2 Podophyllotoxin 0.03 0.03 0.005 0.00 0.08 0.04 0.00 0.003 0.004 0.4 Vinbiastine 0.05 0.06 0.01 0.02 0.04 0.1 0.02 0.01 1.1 0.3 Vincristine 0.01 0.01 0.02 0.02 0.00 0.1 0.05 0.02 0.06 0.4 Betulinic acid (1) has the structural formula: Betulinic acid is fairly widespread in the plant kingdom, and, as a compound frequently encountered, some previous biological activities have been reported. Betulinic acid was obtained by extracting a sample of air-dried, milled stem bark (450 g) of Z. mauritiana with 80% aqueous methanol. The aqueous methanol extract then was partitioned successively with hexane and ethyl acetate to provide hexane, ethyl acetate and aqueous extracts. Among these extracts, the ethyl acetate (13.5 g) extract showed cytotoxic activity against a cultured melanoma cell line (MEL-2) with an ED 50 of 3.7 μg/ml. The ethyl acetate extract was chromatographed on a silica gel column using hexane-ethyl acetate (4:1 to 1:4) as eluent to give 10 fractions. Fractions 3 and 4 were combined and subjected to further fractionation to afford an active fraction (fraction 16) showing a major single spot by thin-layer chromatography [R f 0.67: CHCl 3 :MeOH (chloroform:methanol) (10:1)], which yielded 72 mg of colorless needles after repeated crystallization from methanol (overall yield from dried plant material: 0.016% w/w). As confirmed by the data summarized in Table 1, betulinic acid has been reported as noncytotoxic with respect to cultured KB cells. Cytotoxicity of the crude extracts and purified compounds was determined in a number of cultured human cancer cell lines. Table 1 sets forth the various types of cancer cells evaluated. The cells were cultured in appropriate media and under standard conditions. To maintain logarithmic growth, the media were changed 24 hours prior to cytotoxic assays. On the day of the assay, the cells were harvested by trypsinization, counted, diluted in media, and added to 96-well plates containing test compounds dissolved in DMSO; the final DMSO concentration was 0.05%. The plates were incubated for three days. Following the incubation period, the cells were fixed and stained with sulforhodamine B (SRB) dye. The bound dye was liberated with Tris base, and the OD 515 was measured on an ELISA reader. The growth of the betulinic acid-treated cells was determined by the OD 515 values, and the growth was compared to the OD 515 values of DMSO-treated control cells. Dose response studies were performed to generate ED 50 values. The isolated active compound, betulinic acid (ED 50 of 2.0 μg/ml for MEL-2), has a molecular formula of C 30 H 48 O 3 , as determined by high-resolution mass spectral analysis, a melting point range of 292-293° C. (decomposition). The literature melting point range for betulinic acid is 290-293° C. A mixed melting point range with a known sample of betulinic acid was not depressed. The optical rotation of the compound was measured as +7.3° (c=1.2; pyridine) (lit. +7.5°). The identity of the isolated compound as betulinic acid was confirmed by comparing the above physical properties, as well as 1 H-nmr, 13 C-nmr and mass spectral data of the isolated compound, with physical data and spectra of a known sample of betulinic acid as reported in the literature. To test the in vivo ability of betulinic acid to serve as an antineoplastic agent against malignant melanoma, a series of studies was performed with athymic (nude) mice injected subcutaneously with human melanoma cells (MEL-2). The initial study investigated the activity of betulinic acid against unestablished tumors. Treatment with betulinic acid began on day 1, i.e., 24 hours, following tumor cell injection. At doses of 50, 250, and 500 mg/kg (milligram per kilogram) body weight, betulinic acid demonstrated effective inhibition of tumor growth with p values of 0.001 for each dose versus a control ( FIG. 1 ). These results indicate that betulinic acid can be used to prevent melanoma by topical application of melanoma. Such a discovery is important for individuals who are predisposed to melanoma due to hereditary or environmental factors. In particular, the data plotted in FIG. 1 was derived from experiments wherein four week old athymic mice were injected subcutaneously in the right flank with 3.0×10 8 UISO MEL-2 cells. UISO MEL-2 is a cell line derived from metastatic melanoma from human pleural fluid. Drug treatment was initiated on the day following tumor cell injection and continued every fourth day for a total of six doses. Four control animals received 0.5 ml intraperitoneal (IP) of PVP control solution, while treated animals (4 per group) received 50, 250 or 500 mg/kg/dose IP betulinic acid/PVP in deionized H 2 O. Betulinic acid was coprecipitated with PVP to increase solubility and bioavailability. The mice were weighed, and the tumors measured with a micrometer every other day throughout the study. All animals were sacrificed and autopsied on day 33, when the mean tumor volume in the control animals was approximately one cm 3 . There was greater inhibition of tumor growth at the highest dose of betulinic acid versus the lowest dose (p=0.04). Toxicity was not associated with the betulinic acid treatment because toxicity is indicated by loss of body weight or other forms of acute toxicity. No weight loss was observed. Next, in vivo testing of betulinic acid was performed on established melanomas. In this study, treatment was withheld until day 13, by which time a palpable tumor mass was present in all mice. As illustrated in FIG. 2 , under these conditions betulinic acid successfully abrogated tumor growth (p=0.0001). Furthermore, tumor growth did not parallel that of the control (untreated) group even 14 days after the termination of treatment. In particular, with respect to FIG. 2 , four-week-old athymic mice were injected with 5×10 8 MEL-2 cells subcutaneously in the right flank. Four treatment groups of five mice each were studied. In one group, the mice received 250 mg/kg/dose of IP betulinic acid/PVP every third day for six total doses initiated the day following tumor cell injection. The control group received 0.5 ml IP saline. A DTIC treatment group received 4 mg/kg/dose IP DTIC every third day from day 13 to day 28 of the study. The betulinic acid treatment group received 250 mg/kg/dose IP betulinic acid/PVP every third day from day 13 to day 27. The control and DTIC-treated mice were sacrificed and autopsied on day 36 due to their large tumor burden. The remaining mice were sacrificed and autopsied on day 41. As illustrated in FIG. 2 , the efficacy of betulinic acid also was compared to DTIC, which is clinically available for the treatment of metastatic melanoma. The dose of DTIC, which is limited by toxicity, was selected to be equivalent to that administered to human patients. Tumor growth in the betulinic acid-treated group was significantly less than that observed in the DTIC-treated animals (p=0.0001). Compared to controls, DTIC produced a significant, but less pronounced, reduction in tumor growth, with a p value of 0.01. A fourth group in this study was treated with a schedule similar to that in the initial study. Under these conditions, betulinic acid, as demonstrated before, significantly inhibited tumor development (p=0.0001) and caused a prolonged reduction in tumor growth of up to three weeks following treatment termination. FIGS. 4 and 5 illustrate that betulinic acid also showed activity against MEL-1 cells. In particular, with respect to FIGS. 4 and 5 , four week old athymic mice were injected subcutaneously in the right flank with 5.0×10 8 UISO MEL-1 cells. Drug treatment was initiated on the day following tumor cell injection and continued every fourth day for a total of six doses. Four control animals received 0.5 ml intraperitoneal (IP) saline, while treated animals (4 per group) received 5, 50 or 250 mg/kg/dose IP betulinic acid/PVP in dd H 2 O. The mice were weighed, and tumors were measured with a micrometer every third day throughout the study. Treated animals were sacrificed and autopsied on day 41, when the mean tumor volume in the control mice was approximately 0.5 cm 3 . The control mice then received six doses of 50 mg/kg every fourth day beginning day 41 and were sacrificed and autopsied on day 71. The results illustrated in FIGS. 4 and 5 with respect to MEL-1 cells were similar to the results illustrated in FIGS. 1 and 2 . Betulinic acid therefore is active both against MEL-1 and MEL-2 cells. The mechanism by which antitumor agents mediated their activity is of great theoretical and clinical importance. Therefore, the mode of action by which betulinic acid mediates the melanoma-specific effect was investigated. Visual inspection of melanoma cells treated with betulinic acid revealed numerous surface blebs. This observation, as opposed to cellular membrane collapse, suggested the induction of apoptosis. One of the most common molecular and cellular anatomical markers of apoptosis is the formation of “DNA ladders,” which correspond to the products of random endonucleolytic digestion of internucleosomal DNA. Although recent studies have shown that a lack of DNA laddering does not necessarily indicate a failure to undergo apoptosis, double-strand DNA scission that yields a fragment of about 50 kilobase pairs (Kbp) has been shown to consistently correlate with induction of apoptosis by various treatments in a variety of cell lines. Thus, generation of the 50 Kbp fragment is a reliable and general indicator of apoptosis. Generation of the fragment occurs upstream of the process leading to DNA ladders and represents a key early step in the commitment to apoptosis. Therefore, an important feature of the present invention is a method of analyzing and quantifying the formation of the 50 Kbp fragment as a biomarker for induction of apoptosis in human cancer cell lines. This method comprises treatment of cells in culture, followed by analysis of the total cellular DNA content using agarose field-inversion gel electrophoresis. Under these conditions, the 50 Kbp fragment is resolved as a diffuse band. The fraction of the total cellular DNA represented by the 50 Kbp fragment is determined by densitometry on the contour of this band. To investigate the ability of betulinic acid to induce apoptosis, the above-described method was adapted for use with the MEL-2 cell line. As shown in FIG. 3A , time-dependent formation of a 50 Kbp DNA fragment was induced by betulinic acid with MEL-2 cells. Induction was at a maximum after a 56 hour treatment period. After this time period, a decline in the relative amount of the 50 Kbp fragment was observed, probably due to internal degradation. Also observed in the agarose gel were DNA fragments of about 146 and about 194 Kbp, which are theorized to be precursors in the process leading to the formation of the 50 Kbp fragment. Additionally, the induction of apoptosis (50 Kbp fragment) mediated by betulinic acid was dose-dependent ( FIG. 3B ), and the ED 50 value (about 1.5 μg/ml) observed in the apoptotic response closely approximated the ED 50 value previously determined for the cytotoxic response (Table 1). With further respect to FIG. 3A , cultured MEL-2 cells (10 6 cells inoculated per 25 cm 2 flask) were treated with 2 g/ml betulinic acid (200 μg/ml DMSO, diluted 1:100 in media) for 24, 32, 48, 56 and 72 hours. After the treatment, the cells were harvested, collected by centrifugation, then snap frozen in liquid nitrogen for subsequent analysis. Samples were analyzed on a 1% agarose gel in a Hoefer HE100 SuperSub apparatus cooled to 10° C. by a circulating water bath. The electrode buffer was 0.5×TBE buffer containing 0.25 μg/ml ethidium bromide and was circulated during electrophoresis. Each gel included 20 μL Sigma Pulse Marker 0.1-200 Kbp DNA size markers. Prior to sample loading, 50 μL 2% SDS was added to each sample well. Each sample tube was rapidly thawed, then the pelleted cells were immediately transferred in a volume about 50 μL to the well containing SDS. Each well then was overlaid with molten LMP agarose, which was allowed to gel prior to placing the gel tray in the SuperSub apparatus. Electrophoresis was performed at 172 volts for a total of 18 hours using two sequential field inversion programs with pulse ramping. The DNA/ethidium bromide fluorescence was excited on a UV transilluminator and photographed using Polaroid type 55 P/N film. The negative was analyzed using a PDI scanning densitometer and Quantity One software. The intensity of the 50 Kbp fragment was determined by measuring the contour optical density (OD×mm 2 ) as a percent of the total optical density in the sample lane, including the sample well. The decrease in the 50 Kbp band definition caused by internal degradation, and does not represent a reversal of the process. With further respect to FIG. 3B , cultured MEL-2 cells were treated for 56 hours with the following concentrations of betulinic acid: 0, 0.1, 1.0, 2.0, 4.0 and 8.0 μg/ml. The cells were harvested and apoptosis measured as described for FIG. 3A . The experiment was repeated and a similar dose-response curve was observed (data not shown). These data suggest a causal relationship, and it is theorized that betulinic acid-mediated apoptosis is responsible for the antitumor effect observed with athymic mice. Time-course experiments with human lymphocytes treated in the same manner with betulinic acid at concentrations of 2 and 20 μg/ml did not demonstrate formation of the 50 Kbp fragment (data not shown) indicating the specificity and possible safety of the test compound. Taking into account a unique in vitro cytotoxicity profile, a significant in vivo activity, and mode of action, betulinic acid is an exceptionally attractive compound for treating human melanoma. Betulinic acid also is relatively innocuous toxicity-wise, as evidenced by repeatedly administering 500 mg/kg doses of betulinic acid without causing acute signs of toxicity or a decrease in body weight. Betulinic acid was previously found to be inactive in a Hippocratic screen at 200 and 400 mg/kg doses. Betulinic acid also does not suffer from the drawback of scarcity. Betulinic acid is a common triterpene available from many species throughout the plant kingdom. More importantly, a betulinic acid analog, betulin, is the major constituent of white-barked birch species (up to 22% yield), and betulin can be converted to betulinic acid. In addition to betulinic acid, betulinic acid derivatives can be used in a topically applied composition to selectively treat, or prevent or inhibit, a melanoma. Betulinic acid derivatives include, but are not limited to esters of betulinic acid, such as betulinic acid esterified with an alcohol having one to sixteen, and preferably one to six, carbon atoms, or amides of betulinic acid, such as betulinic acid reacted with ammonia or a primary or secondary amine having alkyl groups containing one to ten, and preferably one to six, carbon atoms. Another betulinic acid derivative is a salt of betulinic acid. Exemplary, but nonlimiting, betulinic acid salts include an alkali metal salt, like a sodium or potassium salt; an alkaline earth metal salt, like a calcium or magnesium salt; an ammonium or alkylammonium salt, wherein the alkylammonium cation has one to three alkyl groups and each alkyl group independently has one to four carbon atoms; or transition metal salt. Other betulinic acid derivatives also can be used in the composition and method of the present invention. One other derivative is the aldehyde corresponding to betulinic acid or betulin. Another derivative is acetylated betulinic acid, wherein an acetyl group is positioned at the hydroxyl group of betulinic acid. In particular, betulinic acid derivatives have been synthesized and evaluated biologically to illustrate that betulinic acid derivatives possess selective antitumor activity against human melanoma cells lines in vitro. It has been demonstrated that modifying the parent structure of betulinic acid provides numerous betulinic acid derivatives that can be deused to prevent or inhibit malignant tumor growth, especially with respect to human melanoma. The antitumor activity of betulinic acid derivatives is important because betulinic acid, although exhibiting a highly selective activity against melanomas, also possesses a low water solubility. The low water solubility of betulinic acid, however, can be overcome by providing an appropriate derivative of betulinic acid. Modifying the parent structure betulinic acid structure also can further improve antitumor activity against human melanoma. An examination of the structure of betulinic acid, i.e., compound (1), reveals that betulinic acid contains three positions, i.e., the C-3, C-20, and C-28 positions, where functional groups can be introduced. In addition, the introduced functional groups, if desired, then can be modified. Through a series of reactions at these three positions, a large number of betulinic acid derivatives were prepared and evaluated for bioefficacy against a series of human tumor cell lines, especially against human melanoma cell lines. With respect to modifications at the C-3 position of betulinic acid, the hydroxyl group at the C-3 position can be converted to a carbonyl group by an oxidation reaction. The resulting compound is betulonic acid, i.e., compound (2). The ketone functionality of betulonic acid can be converted to oxime (3) by standard synthetic procedures. Furthermore, a large number of derivatives (4) can be prepared through substitution reactions performed on the hydroxyl group of oxime (3), with electrophiles, as set forth in equation (a): wherein R a ═H or C 1 -C 16 alkyl, or R a ═COC 6 H 4 X, wherein X═H, F, Cl, Br, I, NO 2 , CH 3 , or OCH 3 , or R a ═COCH 2 Y, wherein Y═H, F, Cl, Br, or I, or R a ═CH 2 CHCH 2 or CH 2 CCR 1 , wherein R 1 is H or C 1 -C 6 alkyl. When R a is C 1 -C 16 alkyl, preferred alkyl groups are C 1 -C 6 alkyl groups. The ketone functionality of betulonic acid can undergo a reductive amination reaction with various aliphatic and aromatic amines in the presence of sodium cyanoborohydride (NaBH 3 CN) to provide the corresponding substituted amines (5) at the C-3 position, as set forth in equation (b). wherein R b ═H or C 1 -C 10 alkyl, or R b ═C 6 H 4 X. A primary amine derivative, i.e., R b ═H, at the C-3 position can be reacted with a series of acyl chlorides or anhydrides, or alkyl halides, to provide amides and secondary amines (6), respectively, as set forth in equation (c). wherein R c ═COC 6 H 4 X, or R c ═COCH 2 Y, or R c ═CH 2 CHCH 2 or CH 2 CCR 1 . The ketone functionality of betulonic acid can react with a series of lithium acetylides (i.e., LiC≡CR 1 ) to provide alkynyl alcohol derivatives (7) at the C-3 position. Based on the chemical reactivity and the stereoselectivity of the betulonic acid structure, α-alkynyl substituted β-hydroxyl alkynyl betulinic acid are the major products of the reaction, as set forth in equation (d). wherein R d ═CCR 1 , wherein R 1 is H or C 1 -C 6 alkyl. A number of esters also can be prepared by reacting the hydroxyl group of betulinic acid with a variety of acyl chlorides or anhydrides (8), as set forth in equation (e). wherein R e ═R 1 CO or XC 6 H 4 CO. With respect to modification at the C-28 position, the carboxyl group of betulinic acid can be converted to a number of esters (9) and amides (10) by reaction with an alcohol or an amine, respectively, as set forth in equations (f) and (g). Depending on the types of functional groups present on the alcohols or amines, additional structural modification are possible. The carboxyl group also can be converted to a salt, in particular an alkali metal salt, an alkaline earth salt, an ammonium salt, an alkylammonium salt, a hydroxyalkyl ammonium salt, or a transition metal salt. wherein R f ═C 1 -C 10 alkyl, phenyl, substituted phenyl (C 6 H 4 X), or CH 2 CCR 1 . The activated C-28 hydroxyl group of betulin can undergo substitution reactions, like SN-2 type reactions, with nucleophiles to provide an amino (11) or an ether derivative (12), as set forth in equations (h) and (i). wherein R g ═H or C 1 -C 16 alkyl, or R g ═C 6 H 4 X, and wherein R h ═C 1 -C 16 alkyl or C 6 H 4 X. The hydroxyl group at the C-28 position can be oxidized to yield an aldehyde, which in turn can react with hydroxylamine to provide a hydroxyloxime compound. The hydroxyloxime can react with a variety of electrophiles to provide the oxime derivatives (13), as set forth in equation (j). wherein R i ═H or C 1 -C 16 alkyl, or R i ═COC 6 H 4 X, or R i ═COCH 2 Y, or R i ═CH 2 CHCH 2 or CH 2 CCR 1 . The aldehyde at the C-28 position also can react with a series of lithium acetylide compounds to yield a variety of alkynyl betulin derivative (14), as set forth in equation (k). wherein R j ═CCR 1 , wherein R 1 ═H or C 1 -C 6 alkyl. With respect to modifications at the C-20 position, the isoprenyl group at the C-20 position can be ozonized to yield a ketone (15) at C-20 position, as set forth in equation (1). A variety of reactions performed on the ketone functionality can provide a series of different derivatives. For example, the ketone functionality of compound (15) can be easily converted to a variety of oximes. Furthermore, a number of additional oxime derivatives (16) can be prepared through substitution reactions at the hydroxyl group of the hydroxyloxime with electrophiles, as set forth in equation (m). wherein R k ═H or C 1 -C 16 alkyl, or R k ═COC 6 H 4 X or R k ═COCH 2 Y, or R k ═CH 2 CHCH 2 or CH 2 CCR 1 . The ketone functionality also can undergo a reductive amination reaction with a series of aliphatic and aromatic amines in the presence of NaBH 3 CN to provide a corresponding substituted amine (17) at the C-20 position, as set forth in equation (n). wherein R 1 ═C 1 -C 16 alkyl, or R 1 ═C 6 H 4 X, or R 1 ═COC 6 H 4 X, or R 1 ═COCH 2 Y, or R 1 ═CH 2 CHCH 2 or CH 2 CCR 1 . The ketone can be reacted with a series of lithium acetylides to provide alkynyl alcohol derivatives (18) at the C-20 position, as set forth in equation (o). wherein, R m ═CCR 1 . The ketone further can be reduced to a secondary alcohol (19) to react with an acyl chloride to provide a series of esters (20) at the C-20 position, as set forth in equation (p). wherein R n ═H, C 1 -C 16 alkyl, CH 2 CCR 1 , or R n ═CH 3 CO or XC 6 H 4 CO. In addition, a number of different derivatives can be prepared through a combinatorial chemical approach. For example, as set forth below, in the preparation of oximes at the C-20 position, a number of electrophiles, e.g., a variety of alkyl halides, can be added together in one reaction vessel containing the hydroxyloxime to provide a mixture of betulinic acid derivatives. Each reaction product in the mixture can be isolated by using semi-preparative HPLC processes using appropriate separation conditions, then submitted for bioassay. wherein P is a protecting group for the secondary alcohol functionality. A low temperature reaction of betulonic acid with a mixture of lithium acetylides in a single reaction vessel, as set forth below, yielded a mixture of alkynyl alcohols at the C-3 position. Each component in the mixture can be isolated by using semi-preparative HPLC processes using appropriate separation conditions, then submitted for bioassay. In order to demonstrate that betulinic acid derivatives have a potent bioefficacy, various derivatives were subjected to a series of biological evaluation tests. The biological evaluation of the derivatives focused on the activity against human melanoma cell lines. In particular, the following betulinic acid derivatives were prepared and tested for cytotoxicity profile against human melanoma cell lines and against a number of selected nonmelanoma cell lines. The results are summarized in Table 2. The data shows that some hydrogenated derivatives, i.e., compounds 5 and 11, are less active than nonhydrogenated derivatives 13 and 10, respectively. However, other hydrogenated derivatives, i.e., compounds 7 and 6, showed a comparable biological activity to nonhydrogenated derivatives 2 and 8, respectively. Therefore, it is possible to optimize the modification at the C-20 position to yield more potent betulinic acid derivatives. Table 3 contains a summary of data showing the effect of hydrogenation at the C-20 position. TABLE 2 Cytotoxicity Data of Betulinic Acid Derivatives ED 50 [μg/mL] (Std. Dev.) MALE- Compound R 1 R 2 R 3 MEL-2 MEL-6 MEL-8 3M LOX KB  1 O═ CHO CH 2 ═C(CH 3 ) 2 7.4 (2.4) >20 3.2 (1.2) >20 18.5 12.9  2 HO—N═ COOH CH 2 ═C(CH 3 ) 2 2.4 (0.3) 14.8 (2.0) 1.9 (1.0) 15.8 9.1 >20  3 CH 3 O—N═ CHNOCH 3 CH 2 ═C(CH 3 ) 2 >20 >20 >20 >20 >20 20  4 HO—N═ CHNOH CH 2 ═C(CH 3 ) 2 2.2 (0.7) 11.9 (2.7) 1.4 (0.6) 17.5 4.1 3.3  5 CH 3 O—N═ COOH C(CH 3 ) 3 >20 >20 >20 >20  6 O═ COOH C(CH 3 ) 3 0.7 (0.6) 10.8 (2.6) 0.9 (0.4) 20 (Dihydrobetulonic acid)  7 HO—N═ COOH C(CH 3 ) 3 2.2 (0.3) 13.1 (1.1) 1.6 (1.1) 13.9  8 O═ COOH CH 2 ═C(CH 3 ) 2 0.9 (0.8) 15.3 (3.4) 0.4 (0.1) 20 6.9 2.5 (Betulonic acid)  9 H 2 N— COOH CH 2 ═C(CH 3 ) 2 1.3 (0.4) 5.2 (2.6) 1.3 (0.5) 3.1 10 HO— COOH CH 2 ═C(CH 3 ) 2 1.2 (0.1) 13.2 (1.5) 1.0 (0.3) 17.6 (0.5) >20 >20 (Betulinic acid) 11 HO— COOH C(CH 3 ) 3 5.8 >20 >20 (Dihydrobetulinic acid) 12 HO— CH 2 OH CH 2 ═C(CH 3 ) 2 >20 >20 >20 (Betulin) 13 CH 3 O—N═ COOH CH 2 ═C(CH 3 ) 2 8.3 >20 4.3 14 HO— COOCH 3 CH 2 ═C(CH 3 ) 2 8.3 12.5 11.8 (Methyl betulinate) 15 HO— CH 3 CH 2 ═C(CH 3 ) 2 17.6 15.6 >20 (Lupeol) 16 C 6 H 4 COO— CH 3 CH 2 ═C(CH 3 ) 2 >20 >20 >20 (Lupeol benzoate) MEL-2, MEL-6, MEL-8, MALE-3M, and LOX are melanoma cell lines, and KB is human oral epidermoid carcinoma. TABLE 3 Cytotoxicity Data of Betulinic Acid Derivatives (Effect of Hydrogenation at C-20) ED 50 [μg/mL] (Std. Dev.) MALE- Compound R 1 R 2 R 3 MEL-2 MEL-6 MEL-8 3M LOX KB 13  CH 3 O—N═ COOH CH 2 ═C(CH 3 ) 2 8.3 >20 4.3 5 CH 3 O—N═ COOH C(CH 3 ) 3 >20 >20 >20 >20 10  HO— COOH CH 2 ═C(CH 3 ) 2 1.2 (0.1) 13.2 (1.5) 1.0 (0.3) 17.6 (0.5) >20 >20 (Betulinic acid) 11  HO— COOH C(CH 3 ) 3 5.8 >20 >20 (Dihydrobetulinic acid) 2 HO—N═ COOH CH 2 ═C(CH 3 ) 2 2.4 (0.3) 14.8 (2.0) 1.9 (1.0) 15.8 9.1 >20 7 HO—N═ COOH C(CH 3 ) 3 2.2 (0.3) 13.1 (1.1) 1.6 (1.1) 13.9 8 O═ COOH CH 2 ═C(CH 3 ) 2 0.9 (0.8) 15.3 (3.4) 0.4 (0.1) 20 6.9 2.5 (Betulonic acid) 6 O═ COOH C(CH 3 ) 3 0.7 (0.6) 10.8 (2.6) 0.9 (0.4) 20 (Dihydrobetulonic acid) The modification of betulinic acid at the C-3 position showed that all compounds, except methoxy oxime 13, expressed a comparable biological activity toward melanoma cell lines (Table 4). Amino compound 9 exhibited an improved cytotoxicity compared to betulinic acid 10. Compounds 2, 8, and 13 showed a decrease in selective cytotoxicity compared to betulinic acid. TABLE 4 Cytotoxicity Data of Betulinic Acid Derivatives (Modification at C-3 Position) ED 50 [μg/mL] (Std. Dev.) Compound R 1 R 2 R 3 MEL-2 MEL-6 MEL-8 MALE-3M LOX KB 10  HO— COOH CH 2 ═C(CH 3 ) 2 1.2 (0.1) 13.2 (1.5) 1.0 (0.3) 17.6 (0.5) >20 >20 (Betulinic acid) 8 O═ COOH CH 2 ═C(CH 3 ) 2 0.9 (0.8) 15.3 (3.4) 0.4 (0.1) 20 6.9 2.5 (Betulonic acid) 2 HO—N═ COOH CH 2 ═C(CH 3 ) 2 2.4 (0.3) 14.8 (2.0) 1.9 (1.0) 15.8 9.1 >20 13  CH 3 O—N═ COOH CH 2 ═C(CH 3 ) 2 8.3 >20 4.3 9 H 2 N— COOH CH 2 ═C(CH 3 ) 2 1.3 (0.4)  5.2 (2.6) 1.3 (0.5)  3.1 With respect to modifications at the C-28 position, the free carboxylic acid group at C-28 position is important with respect to expression of biological activity (Table 5). However, it is unknown whether the size or the strength of hydrogen bonding or the nucleophilicity of the C-28 substituents is responsible for the biological effect. TABLE 5 Cytotoxicity Data of Betulinic Acid Derivatives (Modification at C-28 Position) ED 50 [μg/mL] (Std. Dev.) Compound R 1 R 2 R 3 MEL-2 MEL-6 MEL-8 MALE-3M LOX KB 12 HO— CH 2 OH CH 2 ═C(CH 3 ) 2 >20 >20 >20 (Betulin) 10 HO— COOH CH 2 ═C(CH 3 ) 2    1.2 (0.1) 13.2 (1.5) 1.0 (0.3) 17.6 (0.5) >20 >20 (Betulinic acid) 14 HO— COOCH 3 CH 2 ═C(CH 3 ) 2    8.3 12.5 11.8 (Methyl betulinate) 15 HO— CH 3 CH 2 ═C(CH 3 ) 2   17.6 15.6 >20 (Lupeol) The biological activity changes attributed to oximes is illustrated in Table 6. The hydroxyloxime 4 improved the cytotoxicity profile, although selectivity was lost. It appears that the size of the substituent and its ability to hydrogen bond may influence the expression of the biological activity. TABLE 6 Cytotoxicity Data of Betulinic Acid Derivatives (Effect by Oximes) ED 50 [μg/mL] (Std. Dev.) Compound R 1 R 2 R 3 MEL-2 MEL-6 MEL-8 MALE-3M LOX KB 12  HO— CH 2 OH CH 2 ═C(CH 3 ) 2 >20 >20 >20 (Betulin) 1 O═ CHO CH 2 ═C(CH 3 ) 2 7.4 (2.4) >20 3.2 (1.2) >20 18.5 12.9 4 HO—N═ CHNOH CH 2 ═C(CH 3 ) 2 2.2 (0.7) 11.9 (2.7) 1.4 (0.6) 17.5 4.1 3.3 3 CH 3 O—N═ CHNOCH 3 CH 2 ═C(CH 3 ) 2 >20 >20 >20 >20 >20 20 The above tests show that modifying the parent structure of betulinic acid can provide derivatives which can be used as potent antitumor drugs against melanoma. Betulinic acid derivatives having a comparable or better antitumor activity than betulinic acid against human melanoma have been prepared. In addition, even though betulinic acid has a remarkably selective antitumor activity, betulinic acid also has a poor solubility in water. The low solubility of betulinic acid in water can be overcome by introducing an appropriate substituent on the parent structure, which in turn can further improve selective antitumor activity. In addition, because the parent compound, betulinic acid, has shown to possess anti-HIV activity, the derivatives also can be developed as potential anti-HIV drug candidates.

Compositions and methods are disclosed for treating melanoma wherein a betulinic acid derivative is the active compound in the composition to be administered. The compositions are optionally applied topically is inserted therefor.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device and a control method of a control valve which is used for an intake air (an intake air-gas) system of an engine. The device is provided the control valve which is an intake air throttle valve provided in the intake air-gas system provided in the intake air-gas system of the engine to control the flow rate of intake air to the engine, oran EGR valve provided in the intake air-gas system of the engine to control the flow rate of EGR gas to the engine; and a control unit which determines a target opening of the control valve used for an intake air-gas system, in response to the operation conditions of the engine, and controls the opening of the control valve used for an intake air-gas system so that the opening conforms with the target opening. 2. Description of the Related Art As a technology reducing NOx in the exhaust gas emitted from an internal combustion engine, an exhaust gas recirculation device (hereafter abbreviated as an EGR device) is known. In the EGR device, a part of the exhaust gas in the exhaust gas passage is extracted as an EGR gas; the EGR gas is returned to an intake air passage through an EGR passage. Hence, when the EGR device is used, a mix of fresh intake air as well as a part of the exhaust gas, namely, an EGR gas is led into a combustion chamber. The EGR device as described above is provided with an EGR control valve; the opening of the EGR control valve is controlled and the flow rate of the EGR gas returned to the intake air passage is controlled. When the EGR control valve in the EGR device becomes out of order, the flow rate of the EGR gas returned to the intake air passage cannot be controlled. Thus, there may arise an apprehension that: the flow rate of the EGR gas becomes in surplus or shortage; or, the flow of the EGR gas is stopped. Hence, various technologies in which a malfunction of the EGR control valve can be diagnosed have been proposed. For instance, JP1998-122058 discloses a technology in which it is judged that the device including an EGR control valve is out of order when the device confirmed that a detected actual valve opening does not change in response to the target valve opening, while the device is detecting the actual valve opening by use of an actual valve opening detecting means. Hereby, the actual valve opening changes according to the change of the target opening after the target opening begins changing in a case where an EGR operation condition under which the target opening of the EGR control valve changes over a predetermined value holds. Further, JP2007-255251 discloses an exhaust gas recirculation device as shown in FIG. 18 , the device having: an EGR control valve 102 provided with a valve shaft 102 b ; a driving means 106 in which a reciprocating shaft 112 arranged on a line extended along the valve shaft 102 b performs a to-and-fro movement in the axis direction; and, a control means (not shown. The exhaust gas recirculation device is configured so that the reciprocating shaft 112 of the driving means 106 opens the EGR control valve 102 by pressing an edge point of the center axis of the EGR control valve 102 , and the control means judges the occurrence of the malfunction of the EGR control valve 102 by the magnitude level of a duty ratio of the control signal oscillated toward the driving means 106 from the control means. SUMMARY OF THE INVENTION 1. Subjects to be Solved However, in each of JP1998-122058 and JP2007-255251, even in a case where the EGR control valve is out of order, the actual opening of the EGR control valve agrees with the target opening of the valve; thus, the malfunction of the valve cannot be detected under an operating condition that the target opening is not changed. Above all, in a case where the target opening of the EGR control valve is 0, the EGR control valve with its own structure is provided with a function to press the valve toward the full closed direction; thus, the actual opening apparently follows the target opening so that it is difficult to detect the malfunction. Further, in relation to the EGR control valve including the control valve disclosed by each technology of JP1998-122058 and JP2007-255251, when the opening is kept at a certain same level for a long duration of time, there arises a problem of loss of lube-oil (oil film breakage) in the motor bearing 101 as shown in FIG. 18 , because of minutely small rotation perturbation of an EGR motor. Thus, the damage of the motor bearing is caused by the loss of the lube-oil, and a risk of malfunction or sticking of the EGR control valve arises. Further, under the operation condition that the actual opening agrees with the target opening and the target opening is unchanged as described above, the malfunction of the control valve cannot be detected. Further, when the opening is kept at a certain same level for a long duration of time, there arises a problem of control valve sticking due to the loss of lube-oil. These problems are not limited to only the EGR control valve but also a control valve used in an air intake system of an engine, for instance, a throttle valve installed in the intake passage through which the air from the outside is supplied to the engine. Consequently, in view of the problems in the conventional technologies, the present invention aims at providing a control device and a control method of a control valve which is used for an intake air-gas system of an engine, wherein: the malfunction of the control valve used for the intake air-gas system can be detected even under the operation condition that the actual opening agrees with the target opening and the target opening is unchanged; and the control valve sticking attributable to a damage of the motor bearing can be prevented, the damage being caused by a lube-oil loss due to the condition that the opening of the EGR control valve is kept at a same constant level for a certain long duration of time. 2. Means to Solve the Subjects In order to overcome the problems as described above, the present invention discloses a control device of a control valve used for an intake air-gas system of an engine. The device includes, but is not limited to: the control valve which is an intake air throttle valve provided in the intake air-gas system provided in the intake air-gas system of the engine to control the flow rate of intake air to the engine, or an EGR valve provided in the intake air-gas system of the engine to control the flow rate of EGR gas to the engine; and a control unit which determines a target opening of the control valve in response to the operation conditions of the engine, and controls the opening of the control valve so that the opening conforms with the target opening, wherein the control unit is configured so that, in a case where the target opening is maintained at a same level during over a fixed duration, the target opening is changed, in time, from the target opening which is determined in response to the operation conditions of the engine and controls the opening of the control valve, in order to prevent the control valve from being out of order as well as in order to detect a failure of the control valve. By changing the target opening in time, the opening of the control valve used for the intake air system can be prevented from being kept at a same constant level for a certain long duration of time. Hence, the sticking problem and the like of the control valve used for the intake air system can be avoided. The sticking problem and the like is attributable to the motor bearing damage caused by a lube-oil loss due to the condition that the opening of the EGR control valve is kept at a same constant level for a certain long duration of time. Further, according to the above, the target opening is changed in time; thus, the technology as disclosed above can be free from a conventional problem that the malfunction cannot be detected under the operation condition that the target opening stays unchanged. Further, according to the present invention, by confirming the tracking performance of the actual opening of the control valve used for the intake air system in response to the target opening, the malfunction of the control valve used for the intake air system can be detected. A preferable embodiment of the invention is the control device of the control valve used for the intake air-gas system of the engine. The control unit changes the target opening, in time, in a range of a dead zone where the flow rate of the intake air or the flow rate of the EGR gas is not influenced by the opening of the control valve used for the intake air-gas system even when the opening of the control valve is changed. In the operating range of the opening of the control valve such as the EGR control valve or the throttle valve used for the intake air system, there is a dead zone in which the parameters such as the EGR gas flow rate, the EGR gas mixing ratio (i.e. EGR ratio) in the intake air, the intake-air flow rate, the oxygen excess ratio and the air excess ratio are almost unchanged even when the opening of the valve is changed. The condition of the dead zone or the existing range of the dead zone is different a control valve to a control valve and depends on the size or the structure of the valve; the range of the dead zone of a control valve is an intrinsic property of the control valve. The dead zone is usually an opening range of about 60 to 100% of the total opening range. Even when the target opening is changed in time in the dead zone and the opening of the control valve used for the intake air system is changed in response to the target opening, there is little influence on the parameters such as the EGR gas flow rate, the EGR gas mixing ratio (i.e. EGR ratio) in the intake air, the intake-air flow rate, the oxygen excess ratio and the air excess ratio. Hence, the present invention can be put into practice without influencing on the engine operation condition. Another preferable embodiment of the invention is the control device of the control valve used for the intake air-gas system of the engine, wherein, in temporally changing the target opening, the control unit judges that the control valve used for the intake air-gas system is out of order, in a case where a time duration in which the difference between the target opening and the actual opening of the control valve used for the intake air-gas system exceeds a predetermined allowable level continues over a predetermined allowable time duration. In this way, the malfunction of the control valve used for the intake air system can be surely detected. Another preferable embodiment of the invention is the control device of the control valve used for the intake air-gas system of the engine, wherein, in changing the target opening, in time, the control unit maintains the target opening without changing the target opening, in a case where the difference between the target opening and the actual opening of the control valve used for the intake air-gas system exceeds a predetermined allowable level. According to the above, it can be identified whether the cause of the malfunction is attributable to a reason that the opening of the EGR valve stays unchanged or another reason that the response to the opening command is slow, the malfunction being a condition that the difference between the actual opening and the target opening of the control valve used for the intake air system exceeds an allowable limit value. Another preferable embodiment of the invention is the control device of the control valve used for the intake air-gas system of the engine, wherein the control unit forcefully fixes the target opening at a constant level in a range within the dead zone in a case where the target opening is not maintained at a same opening level over the fixed duration and the target opening is in the range within the dead zone. According to the above, in a time period where it is unnecessary to change the target opening in time, the control valve used for the intake air system can be prevented from being frequently oscillated within the dead zone. In this way, the troubles such as the wear of the seal of the valve shaft and the exhaust gas leakage from the seal part can be avoided. Another preferable embodiment of the invention is the control device of the control valve used for the intake air-gas system of the engine, wherein: the control unit holds a function representing a relationship between a parameter θ determined in response to the engine operation conditions and the target opening; and the function includes a hysteresis element. Further, as a method contrivance, the present invention discloses a control method of a control valve used for an intake air-gas system of an engine, the method including, but not limited to, the steps of: determining a target opening of the control valve used for an intake air-gas system in response to the operation conditions of the engine, the control valve being an intake air throttle valve to control the flow rate of intake air to the engine or an EGR valve to control the flow rate of EGR gas to the engine; and regulating the opening of the control valve so that the opening conforms with the target opening, wherein, in a case where the target opening is maintained at a same level over a fixed duration in time, the method further includes, but not limited to, the steps of: changing the target opening, in time, from the target opening of the control valve in response to the operation conditions of the engine; and preventing the control valve from being out of order detecting as well as detecting a failure of the control valve. A preferable embodiment of the invention is the control method of the control valve used for the intake air-gas system of the engine, wherein the target opening is changed, in time, in a range of a dead zone where the flow rate of the intake air or the flow rate of the EGR gas is not influenced by the opening of the control valve used for the intake air-gas system even when the opening of the control valve is changed. Another preferable embodiment of the invention is the control method of the control valve used for the intake air-gas system of the engine, wherein, in changing the target opening, in time, it is judged that the control valve used for the intake air-gas system is out of order, in a case where a time duration in which the difference between the target opening and the actual opening of the control valve used for the intake air-gas system exceeds a predetermined allowable level continues over a predetermined allowable time duration. Another preferable embodiment of the invention is the control method of the control valve used for the intake air-gas system of the engine, wherein, in changing the target opening, in time, the target opening is maintained without changing the target opening, in a case where the difference between the target opening and the actual opening of the control valve used for the intake air-gas system exceeds a predetermined allowable level. Another preferable embodiment of the invention is the control method of the control valve used for the intake air-gas system of the engine, wherein the target opening is forcefully fixed at a constant level in a range within the dead zone in a case where the target opening is not maintained at a same opening level over the fixed duration and the target opening is in the range within the dead zone. 3. Effects of the Invention According to the present invention, a control device and a control method of a control valve which is used for an intake air-gas system of an engine can be supplied, wherein: the malfunction of the control valve used for the intake air-gas system can be detected even under the operation condition that the actual opening agrees with the target opening and the target opening is unchanged; and the control valve sticking attributable to damage of the motor bearing can be prevented. The damage is caused by a lube-oil loss due to the condition that the opening of the EGR control valve is kept at a same constant level for a certain long duration of time. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an outline of an EGR device to which a control device of an EGR control valve is applied; FIG. 2 shows an example of the control logic by which an ECU performs the control; FIG. 3 is a graph which shows an example of a characteristic of the EGR control valve; FIG. 4 is a graph which shows an example of a characteristic of a throttle valve; FIG. 5 shows an example of a function which determines the opening of the EGR control valve based on a parameter θ in a first mode as well as an example of a function which determines the opening of the throttle valve based on the parameter θ in the first mode; FIG. 6 is a graph which shows the change of the target opening of the EGR control valve in response to an elapsed time, in a case where the target opening of the EGR control valve is changed in a dead zone; FIG. 7 is a graph which shows the change of the target opening of the throttle valve in response to an elapsed time, in a case where the target opening of the EGR control valve is changed in the dead zone; FIG. 8 is a flow chart which shows the control processes regarding the change of the target opening of the EGR control valve in the first mode; FIG. 9 is a flow chart which shows the processes handling the judgment regarding the dead zone; FIG. 10 is a flow chart which shows the processes handling the judgment regarding an abnormal condition in a case where the EGR control valve is in a sticking prevention operation mode; FIG. 11 shows another example of a flow chart which shows the processes handling the judgment regarding an abnormal condition in a case where the EGR control valve is in a sticking prevention operation mode; FIG. 12 is a graph which shows the change of the target opening of the EGR control valve in response to elapsed time, under a condition that the target opening of the EGR control valve is near zero; FIG. 13 is a graph which shows the change of the target opening of the throttle valve, under a condition that the target opening of the EGR control valve is near zero; FIG. 14 shows an example of a function which determines the opening of the EGR control valve from a parameter θ in a second mode; FIG. 15 is a flow chart which shows the control processes regarding the change of the target opening of the EGR control valve in the second mode; FIG. 16 is a flow chart which shows the processes regarding the judgment of a hysteresis behavior; FIG. 17 is a flow chart which shows the processes in the hysteresis behavior mode; and FIG. 18 shows a cross section around a conventional EGR control valve. DETAILED DESCRIPTION OF THE INVENTION Hereafter, the present invention will be described in detail with reference to the modes or embodiments shown in the figures. However, the dimensions, materials, shape, the relative placement and so on of a component described in these modes or embodiments shall not be construed as limiting the scope of the invention thereto, unless especially specific mention is made. (First Mode) FIG. 1 shows an outline of an EGR device to which a control device of an EGR control valve according to a first mode of the present invention is applied. In FIG. 1 , an engine 2 is a four stroke cycle diesel engine of four cylinders. An intake air passage 8 joins the engine 2 via an intake manifold 6 . Further, the engine is connected to an exhaust gas passage 12 via an exhaust manifold 10 . In the intake air passage 8 , a compressor 14 a of a turbocharger 14 is provided. The compressor 14 a is driven by a shaft common to the compressor 14 a and a turbine 14 b as described later. In the intake air passage 8 , on the downstream side of the compressor 14 a , an intercooler 16 is provided. Further, in the intake air passage 8 , on a downstream side of the intercooler 16 , a throttle valve 18 by which the flow rate of the intake air streaming through the intake air passage 8 is regulated is provided. In the exhaust gas passage 12 , the turbine 14 b of the turbocharger 14 is provided. The turbine 14 b is driven by the exhaust gas from the engine 2 . Further, the exhaust manifold 10 is connected to an EGR passage 20 through which a part of the exhaust gas is re-circulated to the intake air side. On apart way of the EGR passage 20 , an EGR cooler 22 and an EGR control valve 24 are provided. The EGR cooler 22 is provided on an exhaust manifold side of the EGR control valve 24 . Heat exchange is performed between the EGR gas and cooling water which pass through the EGR cooler 22 so that the temperature of the EGR gas is reduced. Further, the EGR control valve 24 regulates the flow rate of the EGR gas passing through the EGR passage 20 . The valve opening of the EGR control valve 24 as well as the throttle valve 18 is controlled by an engine control unit (ECU) 40 . The outline of the valve opening control regarding the EGR control valve 24 as well as the throttle valve 18 is now explained. Into the ECU 40 , an actual opening of the EGR control valve 24 as well as the throttle valve is inputted. Further, a detected value (a signal) detected by an intake air temperature sensor 28 fitted to the intake air passage 8 or the intake manifold 6 on the downstream side of the throttle valve 18 is inputted into the ECU 40 , via an A/D convertor 43 ; similarly, a detected value detected by an intake air pressure sensor 30 fitted to the intake air passage 8 or the intake manifold 6 on the downstream side of the throttle valve 18 is inputted into the ECU 40 , via an A/D convertor 44 . Further, a detected value detected by an air flow meter 26 fitted to the intake air passage 8 on the upstream side of the compressor 14 a is inputted into the ECU 40 , via an A/D convertor 42 . Further, a detected value detected by an engine speed sensor 32 is inputted into the ECU 40 , via a pulse counting circuit 47 In the ECU 40 , based on the inputted values as described above, the target opening of the EGR control valve 24 as well as the throttle valve 18 is computed. Based on the computed result, the opening of the EGR control valve 24 is controlled via a driving circuit; and the opening of the throttle valve 18 is controlled via a driving circuit 46 . Further, In a CPU 48 , as well as the throttle valve 18 is controlled via a driving circuit, based on the inputted values as described above, the injection quantity of the fuel supplied to the engine 4 is computed; based on the computed result, the fuel injection quantity is controlled via an injector drive circuit 41 . FIG. 2 shows an example of the control logic by which an ECU performs the control. In the ECU 40 , the air flow rate [kg/s], the engine speed [rpm], the intake manifold air pressure [kPa], the intake manifold air temperature [° C.] and the fuel injection quantity [mg/st] are inputted into a θ target map 51 as well as a λ 02 target map 52 ; based on the inputted values, a target θ and a target λ 02 are generated. Hereby, the θ is a value determined according to the opening of the EGR control valve 24 as well as the throttle valve 18 ; the detail will be described later. Incidentally, the λ 02 is the oxygen excess ratio. Further, an estimated λ 02 is computed by a λ 02 estimating section 53 based on the data (variables) such as the air flow rate [kg/s], the engine speed [rpm], the intake manifold air pressure [kPa], the intake manifold air temperature [° C.] and the fuel injection quantity [mg/st]. Further, the error between the target λ 02 and the estimated λ 02 is computed by a subtraction process 54 . And, based on the error, a PID control 55 is performed. A parameter θ is determined by the PID control 55 ; the θ is added to a target θ; and a saturation operation 57 is performed for the aggregation so that the θ is corrected. Based on the corrected θ, an opening command value for the EGR control valve 24 is determined by use of a function 58 for determining the opening of the EGR control valve 24 , the function 58 being a function with respect to the parameter θ. Further, based on the corrected θ, an opening command value for the throttle valve 18 is determined by use of a function 59 for determining the opening of the throttle valve 18 , the function 59 being a function with respect to the parameter θ. In addition, the functions 58 and 59 are memorized in the ECU 40 in advance. Further, each of the EGR control valve 24 and the throttle valve 18 has a fully opened position as well as a fully closed position. In other word, the opening of each valve shows saturation behavior. Hence, when the opening of the EGR control valve 24 or the throttle valve 18 reaches the fully opened position or the fully closed position, a condition that the control error remains continues. On the other hand, the error which is inputted in the PID control 55 is kept in a non-zero condition. Therefore, the integrated value in the PID control 55 continues to increase. Thus, there arises a problem of a wind-up behavior where the control responsiveness is hindered. In order to avoid the wind-up problem, the difference between the parameter θ as the output of the PID control 55 and the corrected parameter θ as the output of the saturation operation 57 is computed by a subtraction process 60 ; based on the computed difference, namely, an error, an anti-windup compensation is performed. In addition, in the operating range (as to the opening range) of each of the EGR control valve 24 and the throttle valve 18 , there is a characteristic range (hereafter called a dead zone) in which the parameters such as the EGR gas flow rate, the EGR gas mixing ratio (i.e. EGR ratio) in the intake air, the intake-air flow rate, the oxygen excess ratio and the air excess ratio are almost unchanged even when the opening of the valve is changed. Based on FIGS. 3 and 4 , the above-described dead zone is hereby explained with the oxygen excess ratio as an example of the parameters. FIG. 3 is a graph which shows an example of a characteristic of the EGR control valve 24 ; and FIG. 4 is a graph which shows an example of a characteristic of a throttle valve 18 In FIG. 3 , the vertical axis denotes the oxygen excess ratio λ 02 , whereas the lateral axis denotes the valve opening [%] of the EGR control valve 24 . Further, in FIG. 3 , the vertical axis denotes the oxygen excess ratio λ 02 , whereas the lateral axis denotes the valve opening [%] of the throttle valve 18 . As shown in FIG. 3 , in a case of the EGR control valve 24 , the oxygen excess ratio λ 02 is almost unchanged when the opening of the EGR control valve 24 is in a range of about 60 to 100%, especially, in a range of about 80 to 100%. In other words, regarding the EGR control valve 24 having the characteristic as shown in FIG. 3 , the range of about 60 to 100% can be called the dead zone of the EGR control valve 24 . Incidentally, in the dead zone, the variables such as the EGR gas flow rate, the EGR gas mixing ratio (i.e. EGR ratio) in the intake air, the intake-air flow rate, and the air excess ratio other than the oxygen excess ratio λ 02 are also almost unchanged with respect to the change of the opening of the EGR control valve 24 , the variables being dependent on the valve opening. In a similar way, regarding the throttle valve 18 having the characteristic as shown in FIG. 4 , a range of about 70 to 100%, especially, a range of about 80 to 100% can be called the dead zone as to the opening of the throttle valve 18 . The upper side of FIG. 5 shows an example of a function which determines the opening of the EGR control valve 24 with respect to a parameter θ, whereas the lower side of FIG. 5 shows an example of a function which determines the opening of the throttle valve 18 . The upper side and the lower side correspond to the functions 58 and 59 as shown in FIG. 2 , respectively. In the upper side drawing of FIG. 5 , the vertical axis denotes the target opening (the command opening) as to the EGR control valve 24 and the lateral axis denotes the parameter θ; and, in the lower side drawing of FIG. 5 , the vertical axis denotes the target opening (the command opening) as to the throttle valve 18 and the lateral axis denotes the parameter θ. Hereby, θ is a variable dependent on the opening of the EGR control valve 24 as well as the throttle valve 18 . Further, when the opening of the EGR control valve 24 is 100%, the opening (0 to 100%) of the throttle valve 18 is expressed as θ to 1. In a similar way, when the opening of the throttle valve 18 is 100%, the opening (0 to 100%) of the EGR control valve 24 is expressed as 2 to 1. Hence, in the upper side drawing of FIG. 5 , the target opening of the EGR control valve 24 is 100% in response to the parameter θ in the range of θ=0 to 1; and, the target opening of the EGR control valve 24 monotonically and linearly decreases from 100% to 0% in response to the parameter θ in the range of θ=1 to 2. In the lower side drawing of FIG. 5 , the target opening of the throttle valve 18 monotonically and linearly increases from 0% to 100% in response to the parameter θ in the range of θ=0 to 1; and, the target opening of the throttle valve 18 is 100% in response to the parameter θ in the range of θ=1 to 2. Further, in the upper side drawing of FIG. 5 , the area expressed by a symbol ‘a’ corresponds to the dead zone of the EGR control valve opening; on the other hand, the area expressed by a symbol ‘b’ is an area in which the sensitivity to the EGR control valve opening change can be acknowledged. In a similar way, in the lower side drawing of FIG. 5 , the area expressed by a symbol ‘a’ corresponds to the dead zone of the throttle valve opening; on the other hand, the area expressed by a symbol ‘b’ is an area in which the sensitivity to the throttle valve opening change can be acknowledged. Hereby, based on the control logic as shown in FIG. 2 , a case where the parameter θ smaller than 1.0 is outputted as a command value (signal) is discussed. In this event, as is clear from FIG. 5 , the target opening of the EGR control valve 24 is 100% in view of the conventional approach; accordingly, the opening of the EGR control valve 24 stays at an almost constant level (100%) for a long duration of time. Thus, in the conventional approach, there arises a problem of loss of lube-oil (oil film breakage) in a motor bearing as shown in FIG. 18 ; a damage of the motor bearing due to the loss of the lube-oil; or, a risk of malfunction or sticking of the EGR control valve. Further, in the conventional approach, when the parameter θ is in the range (smaller than 1.0), the target opening is unchanged; thus, when the EGR control valve fails, the actual opening agrees with the target opening. In other words, in the conventional approach, if the actual opening is 100% in a case of the valve failure, the failure cannot be detected or acknowledged. In the present invention, attention is paid to the fact that, even when the opening of the EGR control valve is changed, the above-described variable such as the oxygen excess ratio λ 02 is almost unchanged in the EGR control valve dead zone in which the opening of the valve is about 60 to 100%; to be more specific, in a case where the target opening of the EGR control valve is maintained at a same constant level for a certain prolonged duration of time, the target opening is intentionally changed in the dead zone, as shown in FIG. 12 with the symbol c. In this way, the target opening of the EGR control valve 24 varies; thus, the malfunction such as sticking of the EGR control valve can be avoided. Hereby, the malfunction such as sticking is attributable to the failure of the motor bearing, the failure being caused by the condition in which the opening of the EGR control valve is kept at a same constant level for a certain prolonged duration of time. Thereby, the failure of the EGR control valve can be detected. Changing the target opening of the EGR control valve in the dead zone as described above is feasible, when the target opening as the function with respect to the parameter θ is in the dead zone; for instance, in the upper drawing of FIG. 5 , this change can be feasible when a condition θ<θ 1 is satisfied. FIG. 6 is a graph which shows the change of the target opening of the EGR control valve in response to elapsed time, in a case where the target opening of the EGR control valve is changed in a dead zone. In FIG. 6 , the vertical axis denotes the target opening of the EGR control valve 24 and the lateral axis denotes the elapsed time. For instance, as shown in FIG. 6 , the target opening of the EGR control valve 24 is changed in time so that the change of the target opening in time forms a wave-shaped function. In this mode of the present invention, the target opening of the EGR control valve is changed so that the graph of the change of the EGR control valve target opening in time is configured as a wave form. As a matter of course, instead of the wave form, the graph of the change may be configured as another kind of geometry such as a rectangular pulse form, so long as the target opening of the EGR control valve is changed in time. FIG. 7 is a graph which shows the change of the target opening of the throttle valve in response to elapsed time, in a case where the target opening of the EGR control valve is changed in the dead zone. In FIG. 7 , the vertical axis denotes the target opening of the throttle valve and the lateral axis denotes the elapsed time. Hereby, the target opening of the throttle valve stays in an unchanged condition. In the next place, the control regarding the above-described change of the target opening of the EGR control valve is now explained in detail by use of a flow chart. FIG. 8 is the flow chart which shows the control processes regarding the change of the target opening of the EGR control valve in the first mode. When a series of control processes starts, it is judged whether or not a cooling water temperature is higher than a temperature T 1 in the step S 101 . The cooling water means the engine cooling water and the temperature T 1 is a prescribed temperature. When the result of the judgment in the step S 101 is negative, namely, when it is judged that the cooling water temperature is not higher than the temperature T 1 , the step S 101 is followed by the step S 108 , where the EGR is stopped so as not to perform the EGR operation; and, the control flow reaches an end. When the result of the judgment in the step S 101 is affirmative, namely, when it is judged that the cooling water temperature is higher than the temperature T 1 in the step S 101 , the step S 101 is followed by the step S 102 . In the step S 102 , the judgment as to the dead zone is performed. This judgment as to the dead zone is performed according to a flow chart as shown in FIG. 9 . By use of FIG. 8 , the dead zone judgment is explained. When the control flow is started it is judged whether or not the condition θ<θ 1 is satisfied in the step S 201 . Hereby, the parameter θ is a value (signal) which is ordered according to the logic described in FIG. 2 . And, the parameter θ 1 is a coordinate of a boundary of the dead zone, the parameter corresponding to the symbol θ 1 in the upper drawing of FIG. 5 . When the judgment result in the step S 201 is affirmative, namely, the condition θ<θ 1 is satisfied, the step S 201 is followed by the step S 202 , where a dead zone judgment flag is set (FLAG=ON). And, the control flow reaches an end (RETURN TO MAIN FLOW). Further, when the judgment result in the step S 201 is negative, the step S 201 is followed by the step S 203 , where a dead zone judgment flag is cleared (FLAG=OFF). And, the control flow reaches an end (RETURN TO MAIN FLOW). When the dead zone judgment according to the flow chart of FIG. 9 is finished at the step S 102 in the flow chart of FIG. 8 , the step S 102 is followed by the step S 103 . In the step S 103 , it is judged whether or not the dead zone flag is ON. When the judgment result in the step S 103 is negative, namely, the dead zone flag is set at the condition FLAG=OFF, the step S 103 is followed by the step S 107 , where the opening of the EGR control valve is controlled according to the opening command for the EGR control valve which is issued the function 58 as is the case with the conventional approach, without forcefully changing the target opening of the EGR control valve. When the judgment result in the step S 103 is affirmative, namely, the dead zone flag is set at the condition FLAG=ON, the step S 103 is followed by the step S 104 . In the step S 104 , it is judged whether or not it is about time to take a measure to prevent the sticking of the valve. As described before, when the opening of the EGR control valve is kept at a constant level for a prolonged duration of time, the problem of loss of lube-oil (oil film breakage) is caused so that the motor bearing is damaged and sticking of the EGR control valve is caused. In other words, when the target opening of the EGR control valve is not kept at a constant level for a long duration of time, the problem such as sticking can be avoided. Based on this reason, in the step S 104 , it is judged whether or not the target opening of the EGR control valve is kept at a constant level over a certain duration of time as well as whether or not the duration of time exceeds a time period of necessary maintenance to take measures to prevent sticking. To be more specific, if the target opening of the EGR control valve stays at a constant level for a prescribed duration of time, it is judged that it is time to take a measure to prevent the sticking of the valve. Incidentally, the prescribed duration of time is to be determined at every EGR control valve in consideration of the performance of the EGR control valve or the periphery devices around the engine. When the judgment result in the step S 104 is negative, namely, when it is judged that it is not time to take a measure to prevent the sticking of the valve, the step S 104 is followed by the step S 107 , where the opening of the EGR control valve is controlled according to the normal control mode of the EGR control valve, namely, without forcefully changing the target opening of the EGR control valve as is the case with the conventional approach. When the judgment result in the step S 104 is affirmative, namely, when it is judged that it is time to take a measure to prevent the sticking of the valve, the step S 104 is followed by the step S 106 , where the opening of the EGR control valve is controlled according to an EGR valve sticking prevention mode. And, the control flow reaches an end. In the EGR valve sticking prevention mode, as is explained by the use of FIGS. 5 and 6 , the target opening of the EGR control valve is changed within a range in the dead zone. In this way, the target opening is controlled so as to be changed; thus, the sticking of the EGR control valve can be avoided. The sticking is attributable to the failure of the motor bearing, and the failure is caused by the condition in which the opening of the EGR control valve is kept at a same constant level for a certain prolonged duration of time. Further, in the EGR valve sticking prevention mode, a malfunction of the EGR control valve can be judged on the basis of the target opening and the actual opening of the EGR control valve. The judgment of the malfunction of the EGR control valve in the EGR valve sticking prevention mode is now explained based on a flow chart of FIG. 10 . FIG. 10 is a flow chart which shows the processes handling the judgment regarding the malfunction of the EGR control valve in the EGR valve sticking prevention mode. In FIG. 10 , when the control flow is started, the step S 301 is performed. In the step S 301 , the target opening, that is, the command opening value of the EGR control valve is computed. The target opening can be obtained by use of the parameter θ and the function 58 after the computation of the parameter θ according to the processes of the logic as shown in FIG. 2 . When the step S 301 is finished, the step S 301 is followed by the step S 302 . In step S 302 , the opening command for the EGR control valve is outputted. When the step S 302 is finished, the step S 302 is followed by the step S 303 . In step S 303 , an EGR valve opening deviation e is computed; whereby, the deviation e means a difference between a command opening value and an actually measured opening value regarding the EGR control valve. When the step S 303 is finished, the step S 303 is followed by the step S 304 . In step S 304 , it is judged whether or not the absolute value |e| (i.e. abs(e)) of the EGR valve opening deviation e is greater than an allowable value. The allowable value means a least upper bound of the absolute value |e| to be allowed while the EGR control valve is used. The allowable value is a value to be determined at every EGR control valve in consideration of the performance of the EGR control valve or the periphery devices around the engine. When the judgment in step S 304 is negative, namely, when the absolute value |e| is not greater than the allowable value, step S 304 is followed by step S 309 , which is described later. When the judgment in step S 304 is affirmative, namely, when the absolute value |e| is greater than the allowable value, the step S 304 is followed by the step S 305 . In the step S 305 , the computation according to the formula (1) below is performed. t e =t e +t s   (1) Hereby, t e is a cumulative time in which the absolute value |e| is greater than the allowable value; t s is an operation period, which is a time span from the start timing to the end timing of the control flow chart in FIG. 10 . Further, the cumulative time t e on the left side of the formula (1) is a current cumulative time; the cumulative time t e on the right side of the formula (1) is a cumulative time at the previous timing before one period. By the computation according to the formula (1), the current cumulative time (sum) in which the absolute value |e| has exceeded the allowable value can be obtained. When the step S 305 is finished, the step S 305 is followed by the step S 306 . In the step S 306 , it is judged whether or not the (current) cumulative time t e computed at the step S 305 is longer than an allowable time span. The allowable time span means an upper bound time within which the accumulation of the cumulative time where the absolute value |e| has exceeded the allowable value (error) is regarded as being allowable. In other words, the allowable time span means an upper bound value of the cumulative time t e . The allowable time span is a value to be determined at every EGR control valve in consideration of the performance of the EGR control valve or the periphery devices around the engine. When the judgment in the step S 306 is affirmative, namely, when the cumulative time t e is longer than the allowable time span, the step S 306 is followed by the step S 307 , where it is judged that the EGR valve malfunctions. In the following step S 308 , the EGR control is stopped, and the control flow reaches an end. When the judgment in step S 306 is negative, namely, when the cumulative time t e is shorter than the allowable time span, the control flow is returned to an end without any other process. When the judgment in step S 304 is negative, or when the judgment in step S 306 is negative, the step S 304 or the step S 306 is followed by the step S 309 , where the cumulative time t e is cleared (t e =0). And, the control flow reaches an end. According to a series of processes shown in the flow chart of FIG. 11 instead of the processes shown in the flow chart of FIG. 10 , it can be judged whether or not a malfunction of the EGR control valve in the EGR valve sticking prevention mode is occurring. Further, FIG. 11 shows another example of a flow chart which shows the processes handling the judgment regarding the malfunction in a case where the EGR control valve is in the sticking prevention operation mode. The steps S 401 to S 405 in the flow chart of FIG. 11 are the same as the steps S 301 to S 305 in the flow chart of FIG. 10 , respectively. In addition, the steps S 407 to S 410 in the flow chart of FIG. 11 are the same as the steps S 306 to S 309 , respectively. Hence, the explanation of the steps S 401 to S 405 and the steps S 407 to S 410 in the flow chart of FIG. 11 is omitted. In FIG. 11 , in a case where it is judged that the absolute value |e| is greater than the allowable value in the step S 404 , the step S 404 is followed by the step S 405 , where the cumulative t e is computed. In the following step S 406 , the opening command for the EGR valve is preserved. By preserving the opening command for the EGR valve in the step S 406 , the cause of the malfunction condition that the absolute value |e|, namely, the absolute value of the difference between the command value and the actual measured-value is greater than the allowable value can be identified. In other words, the cause can be attributed to a reason that the opening of the EGR valve stays unchanged or another reason that the response to the opening command is slow. In this first mode of the present invention, by use of FIGS. 3 to 10 , a case where the opening of the EGR control valve is nearly full-opened and the target opening of the EGR control valve is in the dead zone has been explained thus far. Also, in the other case where the opening of the EGR control valve is nearly full-closed and the target opening of the EGR control valve is not in the dead zone, namely, in the case where the parameter θ is greater than the parameter θ 1 , the target opening of the EGR control valve is changed. In this event, the target opening of the EGR control valve is not in the dead zone; thus, the change of the EGR gas flow rate, the EGR ratio, the intake air flow rate, the oxygen excess ratio, the air excess ratio and so on is sensitive to the change of the opening of the EGR control valve; thus, when the EGR is performed, a small opening change of the EGR control valve influences the reduction of the harmful substances in the exhaust gas. Accordingly, by making a small change to the target opening of the EGR control valve and by confirming the effect of the small change on the reduction of the harmful substances in the exhaust gas, the malfunction of the EGR control valve can be detected. FIG. 12 is a graph which shows the change of the target opening of the EGR control valve in response to elapsed time, under a condition that the target opening of the EGR control valve is near zero. In FIG. 12 , the vertical axis denotes the target opening of the EGR control valve and the lateral axis denotes the elapsed time. As shown in FIG. 12 , the target opening of the EGR control valve is minutely changed. Further, FIG. 13 is a graph which shows the change of the target opening of the throttle valve, under a condition that the target opening of the EGR control valve is near zero. In FIG. 13 , the vertical axis denotes the target opening of the throttle valve and the lateral axis denotes the elapsed time. As shown in FIG. 13 , the target opening of the throttle valve stays unchanged. As described above, in a case where the target opening of the EGR control valve is not in the dead zone, by minutely changing the target opening of the EGR control valve, the malfunction of the EGR control valve can be detected. Further, the sticking of the EGR control valve can be avoided. The sticking is attributable to the failure of the motor bearing, and the failure is caused by the condition in which the opening of the EGR control valve is kept at a same constant level for a certain prolonged duration of time. In a case where the EGR control valve is minutely opened in a manner as described above, smoke may be generated. For all that, smoke is generally generated when the engine speed or the engine load is increased. When the engine is placed in a steady condition, the engine is not connected with the smoke generation. Further, by limiting the opening of the EGR control valve at most to the level of 4 to 8% of the full opening so as to constrain the effect of the flow rate, the problem of smoke generation can be avoided. Further, in the EGR device provided with an EGR cooler as shown in FIG. 1 , the EGR gas including smoke as well as unburned fuel is cooled when the EGR gas passes through the inside of the EGR cooler; and, the smoke is inclined to gradually become a soot deposit. Thereby, the unburned fuel plays the role of a binder of the deposit. In order to prevent the clogging of the EGR cooler, as well as, to prevent the drop in the cooling efficiency of the cooler, it is not performed to minutely change the target opening of the EGR control valve in a case where the target opening stays near 0 under a condition that the temperature of the EGR gas is low. (Second Mode) In a second mode of the present invention, the EGR device to which the EGR control valve is applied as well as the logic of the control thereby is the same as the EGR control valve as well as the logic of the control in the first mode. Hence, FIGS. 1 and 2 which are used in the first mode are also used in this second mode. And, the repetition of explanation is omitted. In the second mode, the function 58 in FIG. 2 is provided with a hysteresis property. As for the function 58 , the parameter θ is the independent variable which determines the opening of the EGR control valve as the dependent variable. FIG. 14 shows an example of a function which determines the opening of the EGR control valve 24 from a parameter θ in a second mode; and, FIG. 14 corresponds to the function 58 in FIG. 2 . In FIG. 14 , the vertical axis denotes the target opening of the EGR control valve and the lateral axis denotes the parameter θ. Further, the area expressed by a symbol ‘a’ corresponds to the dead zone of the EGR control valve opening; on the other hand, the area expressed by a symbol ‘b’ is an area in which the sensitivity to the EGR control valve opening change can be acknowledged. In this second mode, as shown in FIG. 14 , the function 58 is provided with the hysteresis property in the range of θ from θ 2 to θ 3 . And, the parameter θ 3 is a coordinate of a boundary of the dead zone as is the case with the parameter θ 1 in the upper drawing of FIG. 5 and the parameter θ 3 is equal to the parameter θ 1 . In addition, the parameter θ 2 is smaller than the parameter θ 3 . As for the second mode, based on a flow chart as shown in FIG. 15 , the control of the change of the EGR control valve target opening in a case where a function provided with the hysteresis property as shown in FIG. 14 is now explained. FIG. 15 is the flow chart which shows the control processes regarding the change of the target opening of the EGR control valve in the second mode. When the control flow is started, in the step S 501 , it is judged whether or not a cooling water temperature is higher than a temperature T 1 . When the result of the judgment in the step S 501 is negative, namely, when it is judged that the cooling water temperature is not higher than the temperature T 1 , the step S 501 is followed by the step S 508 , where the EGR is stopped so as not to perform the EGR operation; and, the control flow reaches an end. When the result of the judgment in the step S 501 is affirmative, namely, when it is judged that the cooling water temperature is higher than the temperature T 1 in the step S 501 , the step S 501 is followed by the step S 502 . In the step S 502 , a judgment as to a hysteresis behavior (a hysteresis judgment) is performed. The judgment as to the hysteresis behavior is performed according to a flow chart which is shown in FIG. 16 . By use of FIG. 16 , the judgment as to the hysteresis behavior is explained. When the control flow is started, in the step S 601 , it is judged whether or not a hysteresis judgment flag is OFF. The hysteresis judgment flag is a flag by which it is determined, in the step S 503 ( FIG. 15 ) as described later, to perform an EGR valve normal-control-mode or to perform an EGR valve sticking prevention mode. And, the hysteresis judgment flag is a value dependent on the parameter θ. When the judgment result in the step S 601 is affirmative, namely, when it is judged that the hysteresis judgment flag is OFF, the step S 601 is followed by the step S 602 . In the step S 602 , it is judged whether or not the parameter θ which is issued by the logic as shown in FIG. 2 is smaller than the parameter θ 2 . When the judgment result in the step S 602 is affirmative, namely, when it is judged that θ<θ 2 , the hysteresis judgment flag is changed to ON. And, the control flow reaches an end. When the judgment result in the step S 602 is negative, namely, when it is judged that θ≧θ 2 , the hysteresis judgment flag is kept at OFF. And, the control flow reaches an end. Further, when the judgment result in the step S 602 is negative, namely, when the hysteresis judgment flag is ON, the step S 601 is followed by the step S 604 . In the step S 604 , it is judged whether or not the parameter θ is greater than the parameter θ 3 . When the judgment result in the step S 602 is negative, namely, when it is judged that θ≦θ 3 , the hysteresis judgment flag is kept at ON without changing the flag condition. According to the judgment as to the hysteresis behavior as shown in FIG. 16 , regardless of the condition of the current hysteresis judgment flag, the hysteresis judgment flag is ON when θ<θ 2 , whereas the hysteresis judgment flag is OFF when θ>θ 3 . And, the control flow reaches an end. In addition, when θ 2 ≦θ≦θ 3 , the current hysteresis judgment flag is preserved, and the control flow reaches an end. When the hysteresis behavior judgment by the processes as shown in FIG. 16 are finished, the step S 502 in FIG. 15 ends; then, the step S 502 is followed by the step S 503 . In the step S 503 , it is judged whether or not the hysteresis judgment flag is ON. When the judgment result is negative, namely, when the hysteresis judgment flag is OFF, the step S 503 is followed by the step S 507 , where the opening of the EGR control valve is controlled according to the opening command issued by the function 58 toward the EGR control valve without forcefully changing the target opening of the EGR control valve. When the judgment result is affirmative, namely, when the hysteresis judgment flag is ON, the step S 503 is followed by the step S 504 . In the step S 504 , it is judged whether or not it is time to take a measure to prevent the sticking of the valve. As for the time to take a measure to prevent sticking, the explanation is the same as that in the step S 104 of FIG. 8 ; hence, repetition of the explanation is omitted. In the step S 504 , when the judgment result is affirmative, namely, when it is judged it is time to take a measure to prevent sticking, the step S 504 is followed by the step S 506 , where the opening of the EGR control valve is controlled according to the EGR valve sticking prevention mode. And, the control flow reaches an end. In the EGR valve sticking prevention mode, as is explained by use of FIGS. 5 and 6 in relation to the first mode, the target opening of the EGR control valve is changed within a range in the dead zone. Further, according to a series of processes shown in the flow chart of FIG. 10 or 11 , the judgment as to whether or not a malfunction of the EGR control valve is occurring is performed. In the step S 504 , when the judgment result is negative, namely, when it is judged that it is not time to take a measure to prevent sticking, the step S 504 is followed by the step S 505 , where the hysteresis behavior mode e is taken. And, the control flow reaches an end. Based on FIG. 17 , the procedure in the hysteresis behavior mode is explained. FIG. 17 is a flow chart which shows the procedure in the hysteresis behavior mode. When the control flow is started in FIG. 17 , the step S 701 is performed. In the step S 701 , the opening of the EGR control valve is fixed at 100%. And, the control flow reaches an end. In addition, in this second mode, as shown in the step S 701 of FIG. 17 , the opening of the EGR control valve is fixed at 100% in the hysteresis behavior mode; however, if the opening in the dead zone, the opening of the EGR control valve can be fixed at a level other than 100%. In other words, in the hysteresis behavior mode, the opening of the EGR control valve is maintained at a constant level in the dead zone. In a case where the hysteresis behavior mode is applied, the EGR control valve can be prevented from being frequently oscillated within the dead zone. In this way, troubles such as the wear of the seal of the valve shaft and the exhaust gas leakage from the seal part can be avoided. Further, in the hysteresis behavior mode, since the opening of the EGR control valve is maintained at a constant level in the dead zone, the operation according to the hysteresis behavior mode does not influence the EGR gas flow rate, the intake air flow rate, the oxygen excess ratio, the air excess ratio and so on. In the first and second modes as described above, the control of the EGR control valve has been explained; however, the device and the method as described above can be applicable to the throttle valve. The present invention can be used as a control device and a control method of a control valve which is used for an intake air-gas system of an engine. A malfunction of the control valve used for the intake air-gas system can be detected even under the operation condition that the actual opening agrees with the target opening and the target opening is unchanged; and the control valve sticking attributable to a damage of the motor bearing can be prevented. The damage is caused by a lube-oil loss due to the condition that the opening of the EGR control valve is kept at a same constant level for a certain long duration of time.

A control device of a control valve used for an intake air-gas system of an engine. The device includes, but is not limited to: the control valve which is an intake air throttle valve provided in the intake air-gas system provided in the intake air-gas system of the engine to control the flow rate of intake air to the engine, or an EGR valve provided in the intake air-gas system of the engine to control the flow rate of EGR gas to the engine; and a control unit which determines a target opening of the control valve in response to the operation conditions of the engine, and controls the opening of the control valve so that the opening conforms with the target opening.

The present invention relates to simulation and testing of combinations hardware, electronics and software systems, and in particular to a system for coordinating simulation execution of different subsystem models within an overall system model. BACKGROUND OF THE INVENTION When a new system is designed that involves electronics, computers and physical apparatus, it is commonplace now for complex systems to model the prototypical designs using simulation software, to resolve design flaws and generally to improve the system before it is implemented. When such a system includes subsystems of different fundamental types, such as an electronic system coupled with a physical system, each of the subsystems is in conventional approaches modeled independently. This arises in many fields, such as in the design of new automobiles, to name one example. In general, any system that includes at least two of the three categories of subsystems named will have a separate simulation program for each category. In real implementations of the design, the subsystems interact with and affect one another. The electronics system, on-board computer (and control programs) and physical subsystems (steering, brakes, etc.) of an automobile, for instance, cannot be developed independently of one another, but their relationships and interactions must be analyzed. Thus, it would be useful if the simulation programs for these different subsystems could similarly communicate and interact, to determine the effects that are likely to occur in the final product. Conventionally, simulators created to assist in the design of such subsystems 5 lack this interactiveness. SUMMARY OF THE INVENTION A method and apparatus for sequencing the execution of a simulation system comprising at least two subsystem simulators. The simulation system further comprises a first and second simulator, a processor for executing program instructions of a control program stored in a memory coupled to the processor, a router for coupling first simulator inputs and outputs to second simulator outputs and inputs respectively, and an input device including a control and monitor panel for controlling said sequencing. The control program controls a plurality of subsystem simulators and comprises an initiation sequence for initiating execution of a first simulator at an initiation time including defining a first simulator output state, a first execution sequence wherein said first simulator executes a simulation and updates first simulator outputs to said second simulator, means for halting said first execution sequence, a first transfer sequence for transferring first simulator output data to said second simulator inputs, a second execution sequence wherein said second simulator executes a simulation after said first simulator execution has halted, means for halting said second execution sequence at a second halt time equal to the earlier of said first halt time and a change in state of said second simulator outputs, a repeat sequence for restarting said first execution sequence to run until a final simulation time is reached, and a back-up sequence for restarting the first execution sequence at a last verified simulation time. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a system for implementing the invention. FIG. 2 is a block diagram of detail of a router and simulator processes of the invention. FIG. 3 illustrates a brake system in connection with which the system of the invention may be used. FIGS. 4-10 are timing diagrams illustrating the operation of the invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is directed to the simulation of the operation of a physical system interacting with an electronic system, for modeling the design of such systems before actually building them. Conventional electronic and physical system simulators may be used, with some modifications as described below, and their simulation processes are coordinated and controlled by the scheduling method of this invention. In general, the system of the invention may be applied to any two processes that must be synchronized, where a first process moves ahead of the second and may back up if the information or outputs of the second process change. The method of the invention can be implemented in a program stored as code in a computer memory. FIG. 1 shows a system 10 including a central processing unit (CPU) 20 including a microprocessor 30 coupled to input devices 40 , output devices 50 , sensors 60 , and control output interface 70 . The input devices may be user input devices (such as a keyboard) or input hardware from other sources. The output devices will typically be monitors, printers and the like. Sensors 60 are devices for sensing the physical state of a system and sending data representative thereof to the microprocessor. The control interface 70 transmits commands and data from the microprocessor to physical controls for hardware. Each of the foregoing devices 40 - 70 may be any of many conventional devices that are commercially available for control of physical systems. The CPU 20 includes a read-only memory (ROM) 80 and a random access memory (RAM) 90 coupled to the microprocessor 30 . The RAM 90 stores a program including instructions for the microprocessor 30 for executing the method of the invention, this program including modules shown in FIG. 1 : a router 100 , a physical system simulator Sim1 ( 110 ), and an electronic system simulator Sim2 ( 120 ). See FIGS. 1 and 2. The modules 100 - 120 govern different processes in a program implementing the functions of the invention. Modules 100 - 120 together may be referred to as a controller model of the system to be modeled. In the following description, the terms “process”, “simulator” and “module” will be used as appropriate in conjunction with the modules 100 - 140 , depending upon context, and should be understood as referring to the process carried out by the particular module in question, the simulator (e.g. electronic simulator or physical simulator) represented by the module in question, or the software module, respectively. Module 140 (Sim3) is a software module representing a software simulation process that interacts with modules 110 and 120 . In the simulation of an entire system under design, the physical, electronic and software components would all be modeled by these respective system modules, and the modules communicate in a conventional fashion in most respects, with the exception of the new features (including the router 100 ) discussed herein. Thus, the software module 140 may be of conventional design in the field of modeling systems. The system 10 can be used in many different actual settings. For example, an automobile manufacturer will typically design a new automobile by modeling it in a computer program. The model will have many subsystems, and each subsystem will typically have three components: a mechanical component, an electronic component, and a computer control (program) component. This is illustrated in FIG. 3, which shows part of an anti-brake-locking system (ABS) 200 , which itself is a subsystem of a complete braking system (not shown), which in turn is a subsystem of the entire automobile (also not shown). The ABS system 200 is thus a design that might be modeled by a system of the present invention, and for this example includes: a conventional CPU 210 having the necessary memories and a program for controlling the ABS system; brake system electronics 220 coupled to the CPU 210 ; a braking actuator unit 230 controlled by the electronics 220 (and, indirectly, by the computer 210 ); brake pads or calipers 240 controlled by the actuator unit 230 ; a brake disk 250 that rotates with the automobile wheel (not shown); and a rotation sensor 260 that senses the rate of rotation of the disk 250 . The ABS system 200 may be any system that is under design and needs to be modeled and simulated in software; the particular system is not important to the present invention, and could be any system to be modeled that has an electronic component and a physical component. In this example, the physical module 110 would include a representation of the physical components of the ABS system 200 , including the hydraulic system with its actuator 230 , and brake components and sensor 240 - 260 . The electronic module 120 would include a simulator representation of the brake system electronics, and the software module 140 would include a representation of the control software of the ABS system 200 , which resides in a memory (not shown) of the CPU 210 . The present invention is directed particularly to modifications to the physical and electronics modules 110 and 120 over conventional design, and to their interactions via the router 100 . Other than as described below, their interactions with the software module 140 is standard, and thus the software module 140 will not be discussed in detail herein. The physical module 110 can be generated using the commercially available application SystemBuild by Integrated Systems, Inc., and the electronics module can be generated using the commercially available QuickSim II tools by Mentor Graphics. The present invention enhances the capabilities of these otherwise standard applications with interprocess communications (IPC) capability, creating an IPC mechanism and designing a control panel/monitor to provide the user with a centralized simulation-time interface for the integrated simulation environment. Following are short descriptions of aspects of the preferred implementation of the invention, followed by a detailed description of the method of the invention. Modeling Procedure As noted above, the overall closed-loop model of the system to be controlled and the controller are partitioned into two subsystems, the physical (SystemBuild, or SB) subsystem and the electronic subsystem, which may also be referred to as the VHDL (or Visic Hardware Description Language) subsystem, which will run on SystemBuild and QuickSim II simulators, respectively. The portion of the model to be simulated by SystemBuild tool can be defined using the SystemBuild user interface called SystemBuild editor. The user creates a black box description for the VHDL subsystem inside the SystemBuild editor by including a predefined SystemBuild icon, referred to as the VHDL block. The user generates a VHDL description of his/her VHDL subsystem and simulates it with QuickSim II simulator. It will be understood that other commercial or known simulators may equivalently be used. Integrated Simulation Interface The integrated simulation environment preferably has a centralized control panel/monitor 150 , such that the user can control and monitor both simulators 110 and 120 within this process 150 . Proper functionality for starting and stopping both simulators 110 and 120 , and for observing the communication between the processes, should be incorporated. Architecture: Process Functions FIG. 1 shows the architecture of the system of the invention, which includes four processes, namely the processes 100 - 120 and a control process and monitor 150 . The messages between the two simulator processes will be passed through the router 100 following an IPC protocol. The router acts as the server process and the two simulators act as the client processes. This architecture will allow any process to run on any machine attached to the Internet network, hence providing the capability of performing distributed computation using multiple processors concurrently. It would also be possible to define the electronic subsystem 120 as a VHDL block in the SystemBuild (physical) subsystem 110 ; in this case, the VHDL block would be a place holder to facilitate the definition of inputs and outputs between the VHDL and the SB subsystems, and thus would represent communication with the QuickSim II simulation environment. (Functionally, the results will be the same as when the subsystems are separate, as in FIG. 1.) The shared inputs and outputs between the two simulator modules 110 and 120 would be defined by the information entered in the VHDL block in the SystemBuild editor. In this embodiment, the VHDL block inside the SystemBuild editor would require the user to enter the number of inputs, to the VHDL block and number of outputs from the VHDL block. The VHDL model to be loaded on QuickSim II similarly should include information detailing number of inputs and outputs of the VHDL subsystem. It will be left to the user to make the number and names of the input/output points equivalent in both the SB and VHDL subsystems. The number of inputs and outputs and the names along with the types of these signals in the VHDL model should match those entered in the SystemBuild model. In case of a mismatch between the input/output configurations reported by the two simulators, the simulators preferably abort the simulation session by sending proper error messages to each other and to the user via the control panel. During the initialization phase, as discussed in greater detail below, the two simulators exchange information concerning the number of inputs and outputs, names, types and initial values of the signals along with the simulation duration and the units of time. During the course of co-simulation, the physical simulator module 110 preferably takes as inputs integer/logical data types represented by 64 bits of accuracy in signed magnitude form. Simulator Intercommunication The physical and electronic processes 110 and 120 run as independent processes that communicate with each other through the IPC mechanism mentioned above, which preferably employs UNIX system sockets, as illustrated in FIG. 2 . The router 100 is a stand-alone process, and manages the IPC. The router 100 has two main functions: routing the messages, and performing format conversion on the messages when necessary. Both simulators 110 and 120 initially register with the router 100 and send and receive messages via the router. The simulators 110 and 120 employ their own C-function libraries, which in turn employ UNIX system sockets to communicate with the router. This makes it possible both to keep the modification to the SystemBuild simulator to minimum, and also to utilize the IPC Package already available for the QuickSim II simulator. It will be understood that, while the above is the preferred embodiment for the invention, other operating systems, programming languages and commercial applications may be used in place of those discussed. Protocol Asynchronously sent messages form the basis of the communication protocol, with all messages being sent through the router process 100 and with appropriate format conversion being performed by the Router. An asynchronous message sent from the physical process 110 to the electronic process 120 via the router 100 is reformatted by the router and then passed along. Such a message should have the following semantics: units_of_time: units of the real number representing time, e.g., milliseconds or microseconds. (This information is sent once only, during initialization phase.) duration_of_simulation: length of the simulation. (This information is sent once only, during initialization phase.) message_type: type of the message, e.g., initialization, acknowledgment, output posting, current simulation time posting, last verified simulation time posting, simulation state control messages (pause, resume, rerun, and exit). signal_name: name of a signal crossing the VHDL and the SB subsystem boundaries. signal_value: either integer or binary number. signal_type: either integer or logical quantity. signal_time: time of change in the signal value. signal_source: name of the process originating the message. (This information is employed by the router.) signal_destination: name of the process to receive the message. (This information is employed by the router.) A set of functions that make it possible for the physical simulator 110 to communicate with the router 100 using proposed message semantics are defined in Appendix A. These functions include the following (for others, see Appendix A): rti_init(): this function establishes a socket connection to the Router rti_write_output(): sends a message to a designated process via the Router rti_read_input(): retrieves a message from another process via the Router rti_terminate(): closes the socket connection to the Router Appendix A also lists soc_link.* files, along with a specification of library functions. The functions and files listed in Appendix A serve as a guide to the functions that may be used to implement the present invention. Other formulations of functions may be reasonable for particular applications. The semantics of messages sent to the physical process 110 from either the control panel 150 or the electronic simulator 120 via the router 100 are preferably defined as follows: Initialization data from simulator 120 to simulator 110 : message_type, units_of_time, duration_of_simulation, signal_name, signal_type, signal_value Output posting data from simulator 120 to simulator 110 : message_type, signal_name, signal_value, signal_type, signal_time Control data from simulator 120 to simulator 110 : pause (equivalently stop in QuickSim II semantics) resume rerun (equivalently reset and run in QuickSim II semantics) exit (terminate execution of the SystemBuild simulator executable) Appendix B is a C-language source code listing for a preferred implementation of an IPC router for use with the invention. It is one example of how the router may be realized, and many other specific embodiments are possible. User Interface In the preferred embodiment utilizing a SystemBuild simulator for the physical system simulation, the user interface is via a shell script that will invoke the executable for the SystemBuild simulator. The user provides the name of the file that holds the SB subsystem, the name of the top-level superblock, the name of the file that holds the time vector and external input vector, if applicable, and the name of the file where outputs will be stored. Upon invocation of the executable, the SystemBuild simulator enters the run mode after successfully going through the initialization phase and registering with the router. The user is then able to control the flow of SystemBuild simulation by sending messages to SystemBuild simulator from the Control Panel/Monitor via the QuickSim II simulator and the router. The set of actions that may be requested by the user from the SystemBuild simulator should include exit, pause, resume, and rerun. These features are preferred in the user interface, though variations are certainly acceptable, and this particular interface is not necessary to practice the scheduler system of the invention. The creation of such an interface is routine for users of such applications as SystemBuild and QuickSim II, or other simulation applications. Initialization The SystemBuild simulator 110 will enter the initialization phase upon invocation of the executable for the co-simulation session. After registering as a client process with the router 100 , the SystemBuild simulator 110 will first exchange initialization information with the QuickSim II simulator 120 and request that the QuickSim simulator acknowledge the successful termination of the initialization phase. Upon acknowledgment from the QuickSim simulator 120 , the SystemBuild simulator 110 will proceed with the normal execution of the simulation. The content of data exchanged during the initialization phase will include the number of inputs/outputs, signal names, signal types, duration of the simulation and units of time. Any discrepancy detected preferably generates error messages to be sent to the user and to the other process, and the co-simulation session is aborted by both simulators. The method of the invention Synchronization: general considerations. The method of the invention acts as a process scheduler, to synchronize the actions taken by each of the two simulators. The first of the simulations, the SystemBuild simulation, proceeds forward in time as soon as the initialization phase is complete, and starts to integrate the model dynamics. The integration step size is defined by: (1) a set of parameters, some of which are user controllable, and (2) the type of integration algorithm used (fixed step size or variable step size). After model dynamics are integrated forward to the time implied by the integration step size, the SystemBuild simulator computes the outputs of the SB subsystem, and posts any outputs that have changed since the last time they were computed. (In fact, both simulators will post their outputs to one another whenever there is a change in a subset of the overall output signals; however, the VHDL subsystem outputs are potentially able to change much faster in comparison to a change in SB subsystem outputs. As a general matter, the method of the invention is applicable to systems where one simulator is faster than the other, and the two must be coordinated in time.) Even if no SB subsystem outputs have changed, the SystemBuild simulator will nonetheless post its current simulation time to the QuickSim II simulator after each integration step, in order to establish synchronization. Additionally, the SystemBuild simulator will post its last verified simulation time whenever its value is updated. The last verified simulation time is the time in SystemBuild simulation history to which SystemBuild can back up, to if necessary. The SystemBuild simulator then determines whether any inputs are reported by the QuickSim II simulator. If new, valid inputs are reported, they are processed. If no new, valid input is reported by the QuickSim II simulator, the SystemBuild simulator will use the most recently reported values from the QuickSim II simulator. The method of the invention takes as given that the SystemBuild simulator cannot back up past the last verified simulation time, and consequently that all QuickSim II outputs up to the last verified simulation time have been processed by SystemBuild simulator. Hence, the inequalities given by: (1) QuickSim II current simulation time≧SystemBuild last verified simulation time and (2) SystemBuild last verified simulation time≦SystemBuild current simulation time are implied by the definition of the “last verified simulation time”. The method also takes it as given that the QuickSim II simulator cannot back up in time, and therefore the QuickSim II current simulation time will never exceed the SystemBuild current simulation time during the course of simulation. The following inequality is established by this observation: (3) QuickSim II current simulation time≦SystemBuild current simulation time Combining the inequalities given by 1, 2 and 3 above yields the following forward-moving and variable length time window for simulation synchronization: (4) SB last verified sim time ≦QuickSim II current sim time ≦SB current sim time The QuickSim II simulator can move to the next event if and only if: (I) SystemBuild last verified simulation time is equal to QuickSim II current simulation time; (II) QuickSim II has received outputs of SB subsystem evaluated at the current simulation time; and (III) SystemBuild current simulation time is greater than QuickSim II current simulation time. Condition I ensures that the SystemBuild simulator will not back up past the current simulation time of QuickSim II, and therefore is not likely to generate new outputs to be processed by QuickSim II that would require QuickSim II to back up. Condition II ensures that new outputs likely to be generated at the current simulation time will be taken into account by the QuickSim II simulator before it moves to the next point, hence eliminating the need for QuickSim II to back up. Condition III ensures that inequality 3 above is observed. Most dynamic (physical) systems have a settling time on the order of milliseconds or longer, although some dynamic systems (such as the reader arm positioning mechanism of a hard drive) might have settling times on the order of tens of milliseconds. Typical electronic circuit hardware, on the other hand, is likely to have response times on the order of nano- to microseconds. Therefore, the response/settling time of the plant dynamics will be the determining factor for the closed loop response time. This observation indicates that the SB subsystem will not be able to respond to changes in its inputs signals whose frequency of change is higher than the highest frequency response of the plant dynamics. This fact can be used to define a lower bound for two consecutive time points on the SystemBuild simulator time line—i.e., a minimum step size for the integration algorithm—given that all other requirement to define the step size are satisfied. The goal is to prevent SystemBuild simulator integration algorithms from taking unnecessarily small step sizes. It is possible that variable step integration algorithms in SystemBuild can take very large time steps without computing the output. If t n is the last time at which two simulators synchronized, and if t n+1 −t n is very large, then the QuickSim II simulator will have to wait until SystemBuild attempts to synchronize with QuickSim II at time point t n+1 . If the wait by the QuickSim II is likely to become too long, it is possible to limit the integration step size in SystemBuild (by a DTMAX (Δt maximum) parameter, which can be set by the user, to control the maximum step size for the integration algorithm). Synchronization: application to a specific example. FIGS. 4-10 are graphical representations of the method of the invention as applied to the above example of a physical simulator interacting with an electronic simulator, as would be the case if the ABS system of FIG. 3 were to be simulated. These figures will be discussed in light of the following pseudocode for the simulation flow for the SystemBuild simulator (i.e. the physical simulator in this embodiment): A1. Initialize; last verified simulation time=initial simulation time; and current simulation time=initial simulation time. A2. Compute the integration step size and move the dynamics forward in time accordingly. A3. Compute the outputs. A4. Update current simulation time. A5. Post current simulation time to QuickSim II. A6. If outputs changed compared to the most recent time point, then: post the outputs. A7. Check to see if new inputs from QuickSim II are available. A8. If new inputs are available, then: If new inputs are older than current simulation time, then: (a) store new inputs; (b) schedule the time associated with those inputs as output evaluation time; (c) rewind current simulation time to last verified simulation time; (d) integrate dynamics forward in time to the point QuickSim II outputs posted; (e) move last verified simulation time forward to current simulation time; (f) store the state of the SystemBuild simulator; and (g) post the last verified simulation time to QuickSim II. If time lag for new inputs is equal to current simulation time, then: (h) advance last verified simulation time to current simulation time; (i) post the last verified simulation time to QuickSim II; (j) store the state of the SystemBuild simulator; and (k) apply the new input to the system. A9. Check to see if final simulation time is reached. A10. If final simulation time is not reached, then: Go to step A2. A11. Exit. Pseudocode for the simulation flow for the QuickSim II (electronic) simulator is as follows: B1. Initialize; current simulation time=initial simulation time; and last verified simulation time=initial simulation time. B2. Wait until SystemBuild last verified simulation time is equal to QuickSim II current simulation time and SystemBuild reports a current simulation time later than QuickSim II current simulation time. B3. Schedule SystemBuild output evaluation time as QuickSim II event time. B4. Move forward in time to the next QuickSim II internal event or SystemBuild event, whichever comes first. B5. Update current simulation time. B6. Post the current simulation time to SystemBuild. B7. If outputs have changed, then: post the outputs and event time to SystemBuild simulator. B8. If final simulation time is not reached, then: Go to step B2. B9. Exit. In FIG. 4, the time line 300 represents actions taken by the first of the processes, i.e. the physical process of SystemBuild (SB). Time line 310 represents actions taken by the second of the process, in this example the electronic process expressed as a VHDL simulator. At t=0, the SB and VHDL simulators are initialized. In the SB simulator, this includes setting the last verified simulation time to the initial simulation time (i.e. t=0, here), and also setting the current simulation time to the initial simulation time (t=0). The same is done in the VHDL simulator; see steps A1 and B1 in the pseudocode above. Step A2 is now executed, with the SB simulator computing the integration step side (see discussion in previous section), which yields the time step Δt SB (see FIG. 4) for which the SB simulator must now calculate is new outputs. This is represented in FIG. 4 as the target timepoint, or TT. Note that at this point, the “last valid timepoint” (the last time at which the two simulators are synchronized with one another, i.e. at the same time point in their simulation execution and caught up on one another's output values) is time t=0. In practice, the integration step size Δt SB may comprise one to many (e.g. a hundred or more) individual time steps. However, the representation in FIG. 4 is of a single step, the assumption in for this example being that the SB outputs have not changed for the entire step Δt SB . Step B2 is carried out simultaneously with step A2, and causes the VHDL at this point to wait until the current VHDL (i.e. QuickSim II) simulation time is the same as the last verified simulation time of the SB simulator and the SB simulator reports a current simulation time later than the current simulation time for the VHDL simulator. In practice, this means that the VHDL simulator will wait until the SB simulator reaches time TT (see FIG. 4) before executing its own simulation. At step A3, the outputs up to time TT are computed by the SB simulator, and at step A4 the current simulation time is updated. This is then posted to the VHDL simulator (step A5). Arrow 320 in FIG. 4 represents the posting of the current simulation time pursuant to step A5, indicating that the target timepoint has been reached. The VHDL simulator is now free to act. Thus, at step B3, the time TT is scheduled as the next VHDL event time, and at step B4 the VHDL simulator moves forward to the next VHDL event or SB event, whichever comes first. In practice, this will usually be an update to the next time step (a step of Δt QS , as shown in FIG. 5) for the QuickSim II simulator, which will generally be considerably smaller than Δt SB for instance, Atos may be 1. nanosecond, while Δt SB may be 1 millisecond. The actual individual steps sizes for the SystemBuild may, as indicated above, be much smaller than Δt SB ; e.g., if Δt SB is 1 millisecond (0.001 sec.), the individual SB step sizes may be 0.01 to 0.1 millisecond. A typical time for an entire simulation run will typically be many times the amount of time represented by the target time TT; the latter may be 1 millisecond, for instance, while the former is 10-100 milliseconds. At step B5, the VHDL simulator updates the current simulation time (which is the time after taking one time step of size Δt QS ), and at step B6 it posts this to the SB simulator. At this time, also, step A6 is executed such that any changes in the SB outputs since the most recent time point (which in this case was t=0) are posted to the VHDL simulator. If the VHDL outputs have changed (such as because of an electronic event taking place), these are posted, along with the event time, to the SB simulator (step B7). The postings pursuant to steps A6, B6 and B7 are represented by the double-headed arrow 330 in FIG. 5 . It will be noted that, for the very first integration step of the SB simulator, the outputs must be compared with some previous outputs; this can be accomplished by calculating the first (SB) simulator's outputs at t=0, and then comparing subsequent outputs with the t=0 outputs to see if there have been any changes. The same technique can be applied to the second (VHDL) simulator. While the VHDL simulator moves forward, the SB simulator repeatedly checks for new VHDL inputs (step A7). It will be assumed for this example that the outputs of the VHDL simulator do not change before time TT, and thus that the determination in steps A7 and A8 is negative. If the final simulation time is reached, then at step B8 the method proceeds to step B9 and exits. Otherwise, the method proceeds to step B2, and the loop of steps B2 through B8 repeat until the VHDL simulator catches up to the SB simulator. It will be noted that step B2 in this example has no additional effect the second time it is reached, since the VHDL simulator has already waited for the SB simulator to reach time TT. This changes only when a new target time is defined for the SB simulator, which can happen once the VHDL simulator catches up or when the SB simulator has to back up because of a new output from the VHDL simulator, as in the example of FIGS. 7-10. FIG. 6 represents the situation, then, where no new VHDL outputs were generated between times t=0 and t=TT, and so the last valid timepoint has moved up to time TT. In this case, the determination in step A7—which preferably is made at a rate of once every Δt QS seconds—is in each case negative. Thus, step A8 is not executed in this example. At step A9, it is determined whether the final simulation time is reached, and if so the method proceeds via step A10 to exit at step A11. Otherwise, the method loops back to step A2, and executes until the final time (which is set by the user) is reached. In the example of FIGS. 7 through 10, it will be assumed that the VHDL outputs change for some reason during execution of the VHDL simulation. FIG. 7 represents the same stage in this example as FIG. 4 represented for the preceding example; note that the last valid timepoint is again at t=0, and the posting of the new target timepoint is indicated by arrow 340 . In FIG. 8, the SB simulator has reached the target timepoint TT, and the VHDL simulator has executed its simulation for two, time periods Δt QS . At step B7, the determination is therefore positive, so that the new outputs and event time are posted to the SB simulator, as indicated by arrow 350 in FIG. 8 . (Note that the last valid timepoint is still t=0.) The final simulation time has not been reached, so the method proceeds to step B2. At the same time, at step A7 the SB simulator, upon receiving the new outputs as indicated in FIG. 8, proceeds to step A8. The new inputs are, in fact, older than the current simulation time, i.e. their associated event time has a value that indicates it occurs prior to the current simulation time t=TT. Accordingly, the SB simulator takes the actions indicated in step A8(a)-(g), as follows: it stores the new inputs, and schedules the time associated with those inputs (here, t=2*Δt QS ) as the output evaluation time. The SB simulator's current simulation time is then backed up to this evaluation time, as indicated in FIG. 9 (step A8(c)). At step A8(d), the SB simulator now re-executes its simulation from time t=0, but this time only to time t=2*Δt QS instead of to time TT, and the last verified simulation time point is now reset to be this new, current simulation time t=2*Δt QS . At step A8(e), the last verified time is moved to the current simulation time, the state of the SB simulator is stored at step A8(f), and finally at step A8(g) this last verified simulation time is posted to the VHDL simulator. This results in the state represented by FIG. 10, where the two simulators are again synchronized and their valid outputs having been exchanged (indicated by arrow 360 in FIG. 9 ), such that the last valid timepoint has moved up to t=2*Δt QS . The method then proceeds to step A9, at which it is determined that the final simulation time (here, TT) has not been reached, and so proceeds via step A10 to step A2. The further execution of the method is in the same manner as described above, but with time t=2*Δt QS as the new last valid timepoint. If the new outputs generated by the VHDL simulator (represented in FIG. 8) had occurred at the SB simulator's current simulation time of t=TT, then the determination at step A8 would have reflected this, such that steps A8(h)-(k) would have been executed. In this case, the SB simulator advances the last verified simulation time to the current simulation time of t=TT, posts this time to the VHDL simulator, stores the new state of the SB simulation, and applies the new input to the system. If the final simulation time has not been reached, then the method proceeds via step A9 to step A2, as before, and otherwise the method exits. The above examples presume that, during the time t=0 to t=TT (i.e. before TT is reached), none of the outputs of the SB simulator have changed. If any of these outputs changed in that period of time, then the SB simulator would halt, post these outputs to the VHDL simulator, and set a new “last verified simulation time” and “current simulation time”. The VHDL simulator would then run up through the new simulation time, as normal, and the method would begin again from step A1. For this reason, it is preferable, as in the method described, to ensure that the VHDL simulator does not begin its simulation run from the current simulation time until the SB simulator has reached time t=TT or has encountered a new output and posted this to the VHDL simulator as described. One variation on the invention would allow that the VHDL simulator begin its simulation run before the SB simulator has finished its, but if the SB simulator's outputs change before it reaches its target time, this would require that the VHDL simulator be able to back up, if the outputs of the SB simulator engender a new current simulation time that is before the point up to which the VHDL simulator has already run. Application of the Invention to a Physical/Electronic Brake System. The above method applies to a system such as that illustrated in FIG. 3 as follows. The SB module simulates the operation of the physical components of the brake system of FIG. 3, e.g. the disk 250 , the calipers 240 and the actuator unit 230 . In this simple example, the procession of the SB simulator from time t=0 to a target time TT would represent the rotation of the disk 250 through a given angle A(TT), and perhaps also the application of the brakes, such that the calipers 240 are in contact with the disk 250 , as a result of which the disk slows down. Other factors would typically be included in the physical simulation, notably the initial rotational speed of the wheels (and hence disks); the mass of the car; the speed (linear velocity) of the car; and the friction of the wheels with the ground, which affects the rate at which the calipers are able to slow the disks. These factors are all taken into account in producing an SB simulator output of the relevant variables for time t=TT. One of these outputs will be the new rotational rate of the car and the new linear velocity of the car. The SB simulator outputs from time TT are sent to the electronic simulator, which simulates the action of the electronics 220 in cooperation with the rotation rate sensor 260 and the CPU 210 . If no criteria are violated, then the ABS electronics allow the braking to proceed. In this case, the electronic simulator also proceeds to time t=TT, which is reflected in the situation illustrated in FIG. 6 . There may be a violation of ABS criteria, however, such as that the linear velocity of the car is nonzero while the rotational rate of the disk is zero, which would mean that the car is skidding. In this case, the electronics should override the application of the brakes by the driver, to allow the disk to rotate enough to cause the car to stop skidding. Such a case is reflected in the situation illustrated in FIG. 8, wherein at time t=Δt QS , a signal is sent to the physical simulator that conditions have changed, reflecting the conditions that the electronic sensors indicate that the car is skidding, and so new outputs are sent to the physical simulator which cause a slight release of the calipers 240 . The physical simulator must then back up to simulate forward from this new time t=Δt QS , and the process is repeated, as discussed above in connection with FIGS. 9-10. As noted above, the method of the invention takes it as given that one of the simulators, here the electronic (VHDL) simulator, cannot back up, i.e. cannot recover a state from an earlier time than its current simulation time. The other simulator, here the physical (SB) simulator, can back up, and as is clear from the discussion of FIGS. 4-10 above. In principal, an electronic simulator could back up, but since there are on the order of millions of gates in a typical integrated circuit, simulating the operation of all of these gates involves enormous numbers of variables, and accordingly requires large amounts of memory and is very computation-intensive. Generally, the amount of processor power and storage necessary to back up is prohibitive, so as a practical matter a commercially available electronic simulator such as the VHDL simulator will not be able to back up. The physical (SystemBuild) simulator, by way of contrast, may need to deal with thousands, or fewer, rather than millions of variable values, and thus will typically be able to back up. In one millisecond, it may be practical to save five to ten states for such a simulator. In the above example, also, the physical (SB) simulator interval Δt SB was taken as larger than the interval Δt QS for the electronic (QuickSim II) simulator; again, this will be typical for practical applications, though in principle the physical simulator interval could be smaller than the electronic simulator interval. Given the above pseudocode and discussion of the method, it is a straightforward matter for a practitioner in the art to produce the necessary code for his or her particular system, using otherwise conventional simulation programs. Practical applications for the invention include the simulation of any electronically controlled physical devices, such as disk drives, hydraulics, vehicle or airline instrumentation, and so on. The invention is in general applicable to any system that can be modeled using two simulators that interact with one another, where the simulations can proceed semi-independently, but at least one simulator can back up to accommodate changes in outputs from the other simulator. The invention may further be expanded to multi-simulator settings. Although the invention has been described primarily in terms of a physical simulator interacting with an electronic simulator, it is generally applicable to the simulation of any two systems that must interact somehow, and is particularly useful where a first such simulator takes large time steps in its execution, and the second such simulator takes smaller steps, and where the first system is able to back up its simulation if necessary, and the second is not. Appendix A PC INTERFACE FUNCTIONS The current architecture of the IPC library for the SystemsBuild process consists of three hierarchical layers as in Diagram 1 below. Top level functions are prefixed with “rti” and the functions in that layer call functions in the soc_layer. Functions in the soc_layer are prefixed with “soc” and call UNIX socket communication functions. Diagram 1 System Build IPC Library Architecture RTI_NTERF.*FILES Description of Functions in Library rti_pop_input Initializes a set of global variables. rti_push_input Saves the message from other process in a set of global variables. Ideally, this should be some sort of queue/stack to hold dynamically varying number of messages. rti_write_output This function sends a given message to a designated process. rti_read-input This function checks the availability of a message from another process and if there is a message, it fetches the message. rti_init A process other than the router calls this function to request a connection between itself and the router to be established. Function returns a pointer to a structure which holds information concerning the socket descriptor, name of the process which requested the connection and the name of the router. rti_terminate This function closes any socket for which the user can provide a valid socket descriptor. Specification of Functions in Library Global variables struct route { /* actually, a typedef statement is employed to define route */ int this_end; int other_end; int socket; }; route *where; int rti_pop_input(where, t) where->other_end: source process for the input message double t: time tag for the message int rti_push_input(where, info_number, time, attribute, tstore) where->other_: end source process for the message int info_: number type of the message double time: time tag for the message double attribute: value of the input double tstore: last verified simulation time for the message sender process int rti_write_output(where, info_number, time, output, tstore) where->socket=socket descriptor where->this_end=process — 1 /* the process calling this function */ where-other_end=process — 2 /* the destination process for the message */ int info_number={PINIT, VALID} /* message might be for initialization or for normal data exchange */ Returns 0 if write attempt is unsuccessful and 1 if message is successfully delivered. integer info_number, double time, output, and tstore make up the message. int rti_read_input(where, info_number, time, input, tstore) where->socket=socket descriptor where->this_end=process — 1 /* the process calling this function */ where->other_end4=process — 2 /* the originating process for the message */ int info_number={PINIT, VALID} /* message might be for initialization or for normal data exchange */ returns 0 if no message is available returns 1 if a message is fetched and places the message contents in memory locations pointed by integer pointer info_number and double pointers time, input, and tstore. route *rti_init(this_end) int this_end: name of the process that attempts to establish a socket connection to router. upon successfully connecting to the router, returns a pointer to a structure of type route. if connection can not be established, returns a 0. int rti_terminate(where) where->socket=socket descriptor. int rti_write_double(where, module_number, info_number, attribute) int rti_read_double(where, module_number, info_number, attribute) int rti_write(where, module_number, info_number, att_number) int rti_read(where, module_or _group, new_state_or_command, att_number) SOC_LINK.*FILES Description of Functions in Library soc_inform This function prints a message pointed by a pointer passed from the calling routine to standard output. soc_hookup This function establishes a connection with router. soc_hangup Closes the connection to router and discards any pending data. soc_sendmessage This function writes the message by the calling process to a designated socket. I/O type is blocking. soc_getmessage This message reads the message available at a given socket. I/O type is blocking. soc_pollmessage Checks to see if there is a message at any of the open sockets for the process calling. If there is a message, it does fetch the message. I/O type is non-blocking. sock_checkmessage Has the same functionality as soc_pollmessage, however, a timeout value for the polling can be specified. Specification of Functions in Library void soc_inform(buf, io) char *buf; /* pointer to the message string */ int io; /* a flag indicating if a process is sending or receiving a message */ int soc_hookup() returns a socket descriptor for the socket opened for communication with the router. void soc_hangup(sd) int sd; /* socket descriptor for the socket to be closed */ void soc_sendmessage(sd, buf0, buf1, buf2, buf3, buf4) int sd; /* socket descriptor for the socket for which the message is sent */char buf0, buf1, buf2, buf3, buf4; /* message content holders */ void soc_getmessage(sd, buf). int sd; /* socket descriptor for the socket where the message is available */ char *buf; /* pointer to the character array which will hold the message */ int soc_pollmessage(sd, buf) int sd; char *buf; returns a 1 if there is a message; otherwise, returns a 0 int soc_checkmessage (sd, buf, timeout) int sd; char *buf; int timeout; returns a 1 if there is a message; otherwise, returns a 0 Appendix B PROTOTYPE IPC ROUTER AND ASSOCIATED FUNCTIONS DEF.H FILE #ifndef DEF #define DEF /* defines for the system */ #include “. . . /common/router_machine.h” #define QUEUE_LENGTH 4  /* Number of connections to backlog*/ #define ROUTER_PORT 6500 #define WORD 20 #define BUFSIZE 1024 #define FIFO_SZ 3 #define RWUSER 0600 /* expanded message structure: messages are now bigger than  * 5 bytes. Most programs zero out any bytes beyond 5,  * so the new protocol shouldn't matter, since byte [6],  * the length-of-additional-data field will be zero. */ /* message structure: MSG_LENGTH bytes  * byte 0: destination process number  * byte 1: function  * byte 2: topic  * byte 3: value  * byte 4: sending process number  * byte 5: additional bytes used  * byte 6 to byte [5]+6: valid data  * byte [5]+7 to byte 63: don't care (should be zero) */ #define OK 1 #define NAK 2 /* define process numbers for byte 0 */ /* numbers 1 to 127 are valid */ #define PINIT    126 #define SLAVE    1 #define SLAVE1    1 #define SLAVE2    6 #define MONITOR    2 #define MONITOR1    2 #define MONITOR2    3 #define SIM1    4 #define SIM2    5 #define ROUTER    127 /* define messages for byte 1, transaction functions */ #define DDE_INIT 1 #define DDE_TERMINATE 2 #define DDE#REQUEST 3 #define DDE_ADVISE 4 #define DDE_POKE 5 #define DDE_DATA 6 #define DDE_ACK 7 #define DDE_UNADVISE 8 /* define NAK error codes */ #define NAK_ERROR 0 #define MAK_BUSY 1 /* define messages for byte 2, topic values */ /* all machines support these */ #define STATUS 1 /* master */ #define ROUTER_CONNECTIONS 9 /* how many connections are open */ #define EMPTY    0 #define NONEMPTY   1 #define BUSY    2 #define FULL    3 /* define commands */ #define DISPLAY 0 #define EXIT   1 #define INIT   2 #define ACKN   3 #define VALID   4 /* conversion factor */ #define ATOFC 100.0 #endif ROUTER.H FILE /* structure for linked list of sockets */ typedef struct Unit {  char number;  int sd;  struct Unit *next;  struct Unit *prev; } unit; ROUTER.C FILE /* this will be a master type process. It creates a socket  * and responds to messages from the slave server. */ #include <stdio.h> #include <sys/types.h> #include <sys/socket.h> #include <signal.h> #include <sys/time.h> #include <netdb.h> #include <netinet/in.h> #include “DEF.h” #include “router.h” #include “. . . /common/soc_link.h” /* linked list of sockets */ unit *head; /* initialize the linked list */ void initList () {  head=(unit *)malloc(sizeof(unit));  head−>prev = head;  head−>next = head;  head−>number = 0; }; void remove_unit(aUnitp) unit *aUnitp; {  aUnitp−>prev−>next = aUnitp−>next;  aUnitp−>next−>prev = aUnitp−>prev;  /* sd = 0 only occurs for head, and is not a socket */  if (aUnitp−>sd != 0)   {   close (aUnitp−>sd);   };   free(aUnitp); } /* add a socket to the linked list */ int add(sd, number) int sd; /* the socket */ char number; /* 1 − 127, defined process */ {  if ((getsd(number)==0)&&(number>0)) {   unit *temp;   temp = (unit *)malloc(sizeof(unit));   temp−>next = head−>next;   temp−>prev = head;   head−>next = temp;   temp−>sd = sd;   temp−>number = number;   return 0;  } else {   printf (“Router: not a valid process number/n”);   return 1;  }; }; /* interrupt handler */ int onintr() {  unit *index;  unit *next_one;  next_one = head−>next;  while(next_one != head)   {   index = next_one;   next_one = index−>next; /* save pointer because   index WI11 be free()′d */   remove_unit(index);   }  exit() } getSD (number) char number; {  unit *index;  for (index=head−>next; index.!=head; index=index−>next)   {   if (index−>number =≦ number)    {    return index−>sd;    }   }  return 0; } void process(buf, ns) char *buf; int ns; {  unit *index;  char rbuf[256];  int sd;  if (buf[0]!=ROUTER)   { /*    printf(“Router: forwarding message.\n”);*/   sd = getSd(buf[0]);   if (sd != 0)    {    soc_inform(buf,0);    write(sd,buf,MSG_LENGTH);   } else {    printf(“Router: unknown destination\n”);    soc_sendmessage(ns,buf[4]    DDE_ACK,NAK,NAK_ERROR, ROUTER);   }  } else {   /* message for the router */   switch (buf[1])    {    case DDE_INIT:     if(add(ns,buf[4])==0)  {      printf(“Router: adding connection\n”);      soc_sendmessage(ns,buf[4],DDE_ACK,OK,O,ROUT-      ER);  } else {      printf(“Router: connection refused\n”);      soc_sendmessage (ns,buf[4],DDE_ACK,NAK,NAK —      ERROR,ROUTER):    }    break;   default:    printf(“Router: unknown message type\n”);    break;   };  }; }; main() {  int ns;  char buf[256],hstnm[256];  int fromlen;  struct hostent *hp;  struct sockaddr_in sin;  atruct sockaddr client_sa;  int sd, on;  fd_set fdset;  unit *index;  unit *next_one;  initList ();  /* set up router port */  sd = socket(AF_INET, SOCK_STREAM, 0);  strcpy(hstnm,ROUTER_MACHINE);  hp = gethostbyname(hstnm);  bzero((char *)&sin, sizeof(sin));  bcopy(hp−>h_addr, (char *)&sin.sin_addr,hp−>h_length);  sin.sin_port = ROUTER_PORT; sin.sin_family = hp−>h_addrtype; /* set socket option to allow reuse of local addresses */ on = 1; setsockopt(sd, SOL_SOCKET,SO_REUSEADDR, (char *)&on, sizeof(on)); if (bind(sd, (char *)&sin, sizeof(sin)) ==−1)  {  perror(“Router: error in bind”);  exit ()  } add(sd, ROUTER); /* kill all open sockets on a Ctrl-C */ signal (SIGNIT,onintr); /* or a kill %1 command */ signal (SIGTERM,onintr); listen(sd,QUEUE_LENGTH); printf(:Router: available for connections\n”); for (;;)  {  /* load the fdset with all sockets */  FD_ZERO (&fdset);  for(index=head−>next; index?=head; index=index−>next)   {   FD_SET(index−>sd, &fdset);   }  /* now select among the various fd's */  select (getdtablesize(),&fdset,NULL,NULL,NULL);  next_one = head−>next;  while(next_one != head)   {   index = next_one;   next_one = index−>next; /* save pointer in case   index is free()′d */   if FD_ISSET(index−>sd, &fdset)    {    if (index−>number ==ROUTER)     {     ns = accept(index−     >sd,&client_sa&fromlen);    } else {     ns = index−>sd; /* socket is already     connected */    }    bzero(buf,sizeof(buf));    switch (read(ns,buf,MSG_LENGTH)) {     case 0: printf(“Router: end of file,      deleting socket\n”);      remove_unit (index);      break;     case MSG_LENGTH:      soc_inform(buf,1);      process(buf,ns);      break;     default: perror(“Router: error in read”);      onintr(); /* will exit */      break;     }    }   }  } }

A method and apparatus for sequencing the execution of a simulation system comprising at least two subsystem simulators. The simulation system further comprises a first and second simulator, a processor for executing program instructions of a control program stored in a memory coupled to the processor, a router for coupling first simulator inputs and outputs to second simulator outputs and inputs respectively, and an input device including a control and monitor panel for controlling said sequencing. The control program controls a plurality of subsystem simulators and comprises an initiation sequence for initiating execution of a first simulator at an initiation time including defining a first simulator output state, a first execution sequence wherein said first simulator executes a simulation and updates first simulator outputs to said second simulator, a first halt sequence for halting said first execution sequence, a first transfer sequence for transferring first simulator output data to said second simulator inputs, a second execution sequence wherein said second simulator executes a simulation after said first simulator execution has halted, a second halt sequence for halting said second execution sequence at a second halt time equal to the earlier of said first halt time and a change in state of said second simulator outputs, a repeat sequence for restarting said first execution sequence to run until a final simulation time is reached, and a back-up sequence for restarting the first execution sequence at a last verified simulation time.

FIELD OF THE INVENTION [0001] The invention relates to an on-line governmental expert information system and method, and specifically to an expert system that automatically makes decisions regarding the release, handling, transportation and distribution of supervised commercial imported goods which require clearance confirmation. Incorporating a capacity to track handling and transportation in compliance with national and international laws and regulations, the system empowers the enforcement capability of national authorities. BACKGROUND [0002] A country's customs service is the primary enforcement agency responsible for protecting the nation's borders against illegal import/export of goods. Among other things, the Customs Service processes imports to the country and inspects them, in order to ensure compliance with rules and regulations pertaining to other government agencies such as: public health, safety, environmental protection, security, etc. [0003] The U.S. Customs Service typically processes imports on a transactional basis, and must interact with many different parties (such as importers, carriers, suppliers) to process these transactions. The different parties must also interact with each other in order to process a single transaction. [0004] The complex nature of Customs Service rules, necessitates extensive communication among the involved parties. Complying with a myriad of rules and regulations, and tracking the vast number of import transactions processed daily, are challenging tasks for the parties involved. [0005] In order to process this data, the U.S.A. Customs Service uses automated systems such as the Automated Commercial System (ACS). This system currently tracks, controls, and processes commercial goods imported into the United States, but this system is not able to meet the complex requirements of all governmental entities. The U.S. Customs Service has declared the development of a new ACS system (hereinafter referred to as the New ACS System). [0006] The New ACS System is designed to permit certified users to submit import data in electronic form. The system sorts the incoming data according to cargo type, by means of established criteria, and identifies high-risk cargo, in order to determine the proper examination procedure for each type or class of imported goods. The System transfers import data to other governmental agencies for further investigation. The import data of low risk type is examined against national and local criteria and provides certified users with electronic authorization. [0007] The New ACS System suffers from two crucial deficiencies. Firstly, the System is designed to identify high risk goods and to determine the proper examination procedure for each case but is not designed to perform the confirmation procedure. The confirmation of high risk material therefore requires the intervention of a human examiner. The second problem concerns the System's underlying requirement to adhere to the different rules and regulations of a plurality of different governmental authorities, such as the Department of Health, Ministry of Defense, Environmental Department (hereinafter: “Authorities' Rules and Regulations”). Today, the ACS System is required to perform, in respect of each class of goods, a different examination procedure in order to comply with the Authorities' Rules and Regulations. Thus, the process of checking goods compliance is both complicated and cumbersome. Further more, according to a report published in 1999 by the U.S. Customs (“Trade Compliance Risk Management Process”), the ACS system performs only a partial check, by a “Compliance Measurement Sampling Plan”, whilst the present invention presents a system that is able to perform a complete inspection (of goods details compliance) in respect of 100% of the supervised commercial imports. [0008] Most prior art customs information systems are mainly designed to deal with the financial transactions of importing and exporting procedures. [0009] Recently, patent application Ser. No. WO0235382 disclosed a seamless electronic international trading system across national borders. This application deals with the process of checking the compliance of imported goods, but no solution is provided for an automatic confirmation of high-risk goods' compliance with the polarity Authorities' Rules and Regulations. [0010] As the problems concerning compliance confirmation remain unsolved, a new system is required to efficiently deal with international import/export transactions. On such complicated grounds, involving many different parties and organizations, an in-depth and time-consuming analysis of various functional and technical requirements is necessary in order to develop an appropriate solution. [0011] It is the object of the present invention to avoid the deficiencies of the prior art customs information systems and provide an efficient and automatic decision making expert system for checking the compliance of transported goods with all Authorities' Rules and Regulations. SUMMARY OF THE INVENTION [0012] The present invention is a universal on-line expert system for automatic decision making in the release, handling, transportation and distribution of imported and exported goods. In particular, the system relates to high-risk or hazardous goods that would normally require human intervention to examine. These decisions are based on data pertaining to the goods in question, according to at least one set of authorities' rules and regulations relating to the import/export of goods and license limitations of the certified user relating said goods. [0013] The system comprises of several databases that contain the authorities' rules, license information of certified users, and pre-designed electronic data sheets for various types of goods. All components and means of communication may be provided through the Internet or similar type network, enabling users to send required information about the goods from any convenient location and receive a confirmation or non-confirmation of their goods' compliance with authorities' rules prior to transporting the goods. [0014] According to the system, the intervention of a human examiner will only be required when a user has received a non-confirmation of goods' compliance with authorities' rules. Use of the system would be very time and cost effective for the Customs Service, as currently all high-risk materials are examined manually. BRIEF DESCRIPTION OF THE DRAWINGS [0015] These and further features and advantages of the invention will become more clearly understood in light of the ensuing description of a preferred embodiment hereof, given by way of example only, with reference to the accompanying drawings, wherein [0016] [0016]FIG. 1 is a general diagrammatic representation of the environment in which the present invention is practiced; [0017] [0017]FIG. 2 is a block diagram of the supervision system according to the present invention; [0018] [0018]FIG. 3 is a diagram illustrating the process flow of checking and confirming goods compliance according to the present invention; [0019] [0019]FIG. 4 is flow-chart illustrating the data interchange process according to the present invention; [0020] [0020]FIG. 5 is flow-chart illustrating the databases management process according to the present invention; [0021] [0021]FIG. 6 is flow-chart illustrating online goods tracking process according to the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0022] The invention provides a new expert decision making tool for facilitating an efficient and easy-to-use procedure for the automatic confirmation of goods' compliance with a multitude of authorities' rules. [0023] The investigation procedure of goods' compliance is more acute when dealing with high-risk or hazardous materials as well as any other type of goods that require formal examination and authorization before clearance (such as chemical, nuclear or medical materials, food, animals, plants, or communication systems) (hereinafter “Goods Requiring Supervision”). The supervision of importation and handling of goods, which require supervision, is of great importance to most of all national competent authorities. The permission to import, handle and use (hereinafter “Licenses”) these goods is granted to limited number of importers and facilities, such as industrial companies dealing with hazardous materials, or to medical institutes (hereinafter “Certified Users”). The supervision of such goods is primarily preformed by the customs authorities, hence the preferred embodiment of this invention relates to the importation procedure carried out by governmental authorities. However, the basis of the expert system according to the present invention, is to enable the follow-up process (tracking) of Goods Requiring Supervision throughout supply chain process: from the production/manufacture stage through to the final usage (“From cradle to grave”). [0024] [0024]FIG. 1 illustrates the complete cycle of the flow of goods (supply chain process) in which the present invention is practiced. In order to enable automatic information flow and confirmation process, special data sheets are designed, which are recorded in electronic form. These data sheets are designed to include all relevant examination information that covers the requirements of all the Authorities' Rules and Regulations. Each type of goods has different kinds of characteristics, thus for each goods category a special data form is created to include all relevant parameters. The categorization of goods is based on the international harmonized Customs coding system (of the WCO organization). [0025] In FIG. 1, all entities that are involved in the flow cycle are detailed. The materials are manufactured by a foreign manufacturer, which provides the goods' characteristic data. This data information is forwarded to the supplier or directly to the consignor. This data may be transferred in electronic or tangible form. The consignor is obliged to enter the goods' characteristics into the designated data sheet form in order to satisfy all the competent authorities requirements (Consignors may perform a one time modification into their existing supply chain management system, for this purpose). The data sheet records are transferred through electronic communication, preferably through the Internet or any equivalent network. The data transfer through the network is secured and authenticated, using known technologies, including procedures of digital signatures. Thereafter, the data is checked and analyzed by the Supervision System. The Supervision System examines the goods' data sheets and determines if the goods can be imported according to the rules of a specific country. The system notifies the involved participants (the consignor, the importer, the competent authorities and the customs) of confirmation or non-confirmation relating to goods release (and/or handling transportation and/or distribution). A non-confirmation message is enclosed with relevant justification/argument and details of the rejection. This improved process of electronic data transfer between consignor/Certified User and governmental authorities prevents data errors in comparison to human manual process. [0026] The Supervision System may further track the supervised goods transportation, distribution, usage and evacuation, through all the stages of the supply chain process. Such supervision is possible if all relevant participating Certified Users are obliged to provide the supervision system with information relating to the importation, transportation, or usage of the materials in electronic form, preferably through the Internet. [0027] According to a further idea of the present invention, it is suggested to use smart cards, which will include all relevant information of the user's license for Goods Requiring Supervision. These smart cards will replace the paper licenses, and will be issued and updated by the government authorities. A smart card, will be operated on the principle of “phone-card” or even “smart credit card” (with limited amounts of permitted values for usage of each material). For each supervised operation, the user will insert the smart card into a reader and be identified. Then, he will choose one of the menu's options (release/transportation/receiving.). Each Certified User (importer/transporter/user) will be obliged to use this system. The license (smart card) will be issued for limited periods, for limited amounts of materials, and for a specific Certified User. It will also be used as “back-up” means, in case of computer problems. [0028] [0028]FIG. 2 illustrates a block diagram describing the essential components according to the present invention. [0029] The Supervision System includes three databases. The first database includes records of Authorities' Rules and Regulations arranged according to material/goods categories, related Authorities and international customs coding. All rules are transformed into logical terms indicating the permitted range of values for each parameter representing the Goods Requiring Supervision material characteristics or composition. The second database includes license records, each license record includes detailed information of granted permissions to Certified Users. The data record of each Certified User includes a list of all types of permitted materials and goods and the different conditions the Certified User is obliged to maintain. The conditions are represented as logic limitations of material characteristics and compositions. [0030] The third database includes pre-designed data sheet forms. Each data sheet is specially designed for a specific category of materials and includes all relevant parameters that define the materials' characteristics and compositions. [0031] The fundamental component of the Supervision System is the decision making expert application. This application receives the data sheets of the imported goods (step 301 ) as specified by the Certified User or the consignor and identifies (step 302 ) the Certified user or consignor and the goods/material type ( 304 ). The license of the identified Certified User is retrieved (step 303 ) from the second database, and the relevant rules of all authorities are retrieved (step 305 ) from the first database. The application checks all goods/material characteristic values against the logical conditions of the retrieved license and the logical terms of the relevant Authorities' Rules and Regulations (step 306 and 307 ). If one of these characteristic values exceeds the threshold values as defined in any one of the logical conditions, then the goods importation is denied. The decision of approving or denying goods importation can be based on a combination of conditions relating different material characteristics. At the end of the assessment process, the Supervision System informs the involved participants (the consignor, the relevant Certified User, the relevant competent authorities and the customs) by e-mail or any other electronic form of its confirmation or denial of the goods importation. This investigation process may be performed prior to the physical action of transporting the goods and thus enables the consignor (by a way of a query) to know in advance if the delivered goods comply with the Authorities' Rules and Regulations. This element of the Supervision system is especially useful, as it eliminates costs related to the storage of goods while their compliance with the relevant Authorities' Rules and Regulations is assessed. [0032] The interface of the Supervision System may be implemented by way of completion of online forms through the Internet, in which Certified Users may fill-in the data either manually or using unified formats data (e.g. XML) and exchange application software such as Microsoft's BizTalk or any data management software adapted to the supervision system interface, enabling automatic exchange between user applications and the Supervision System. [0033] [0033]FIG. 4 illustrates data interface processing using the online forms option. First, the Certified User (or the consignor) is requested to fill-in it's identity (step 401 ) and to enter the goods/product type ( 403 ). Once the user is identified ( 402 ), the interface application retrieves ( 404 ) the proper data sheet form and presents the user with the respective data sheet fill-in screen ( 405 ). The user enters the data manually or automatically using the data exchange application. The interface application checks the validity of the data type and forms ( 406 ) and notifies the user of improper data type or errors, after which the user may change and edit the data accordingly. At the end of this process the data is transmitted to the decision expert system for investigation (as explained above) and in return, confirmation or non-confirmation of data compliance with Authorities' Rules and Regulations is received. [0034] [0034]FIG. 5 illustrates the management application of the Supervision System databases. The first procedure ( 501 ) enables the Authorities to update the rules and regulations relating to importation of goods. When new rules are inserted, the application transforms them into logical conditions. The management application further updates the relevant data sheet forms and license with the new parameters relating to the goods characteristics as required according to the new rules. Once all system records are updated, the management application informs the relevant Certified Users of new changes that may affect these users' operations. [0035] The second procedure ( 502 ) enables Certified Users (or new applicants) to transmit their requests for new Licenses, to update existing ones, or/and to renew them, by filling e-forms at the relevant governmental web sites. [0036] The check-up process requires human experts intervention, and is performed manually. [0037] In cases of approved releases and handling of consignments, the system information is continuously updated (automatically), according to incoming goods data sheets which include detailed information of new type of goods. [0038] [0038]FIG. 6 illustrates a further implementation of the Supervision System according to the present invention. According to this implementation the Certified User is obliged to report any transportation of Goods Requiring Supervision to a second Certified User, or within the Certified organization, to the authorities. For example, transportation of hazardous material across the country between two different locations by the same Certified User, or relating a second Certified User, can be supervised by the authorities. The Certified Users transmit the relevant data information to the Supervision System and in return, receive confirmation or non-confirmation for proceeding with their transportation request. [0039] According to the process of the present invention, customs authorities have no role in the identification, verification, and approval of contents details that are subjected to other agencies/authorities supervision and decision-making. [0040] The supervision system, as suggested by the present invention, provides convenient and efficient online checkup process enabling 100% examination of all imported goods, reduced costs of business through e-commerce and “Just In Time” reporting and control over goods handling and transportation by Certified Users. It is especially useful in handling data received from “high-frequency” consignors, meaning those who are importing or exporting goods on a regular basis. Exceptional users, who use this service less frequently, are required to submit special forms at authorities' web sites. This process is also simple and quick. [0041] While the above description contains many specifities, these should not be construed as limitations on the scope of the invention, but rather as exemplifications of the preferred embodiments. Those skilled in the art will envision other possible variations that are within its scope. Accordingly, the scope of the invention should be determined not by the embodiment illustrated, but by the appended claims and their legal equivalents.

The present invention is a universal on-line expert system for automatic decision making in the release, handling, transportation and distribution of high-risk goods that would normally require manual examination. The system comprises of several databases that contain the authorities' rules, license information of certified users, and pre-designed electronic data sheets for various types of goods. Relevant information about the goods is sent to the system by a certified user through the Internet or similar type network, and the confirmation or non-confirmation of the goods' compliance with authorities' rules is verified by the system prior to the transportation of the goods.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to remediation of soil contaminated by volatile organic compounds, and in particular to a system for in-situ soil vacuum extraction of the contaminates and the process thereof. 2. Description of the Prior Art Conventional methods of removing contamination from groundwater and soils include excavating the contaminated subsurface material and pumping contaminated water from subsurface materials to the surface for treatment. Both methods are expensive due to the volume of material which must be removed, treated, and disposed. In-situ soil vacuum extraction (ISVE) involves the removal of volatile organic compounds (VOC's). Dissolved VOC's are present in the upper, unsaturated "vadose" zone above the groundwater. The dissolved VOC's approach an equilibrium concentration in the soil's pore space according to Henry's Law. The contaminates can be aliphatic and/or aromatic hydrocarbons, halogenated hydrocarbons, or other volatile organic compounds. Many of these compounds have vapor pressures of at least 20 mmHg at room temperature. Accordingly, such compounds can be easily volatilized when subjected to a suitable vacuum or air flow. The design and operation of ISVE remediation systems are based on the movement of gases in a porous media. Thus, a negative air pressure gradient exerted on the soil will induce migration of the subsurface VOC's. The VOC's can then be collected at extraction point(s) and discharged and collected at the surface. Accordingly, an ISVE remediation system must be designed in accordance with site specific subsurface conditions in order to maximize the rate of contaminant removal. ISVE remediation systems may be either vertical or horizontal wells. Vertical systems become cost competitive with excavation and removal when the vadose zone exceeds about 20 feet in depth. Horizontal systems are more effective where contaminates are very shallow, i.e. less than about 20 feet. However, vertical well systems are prone to plugging. The vacuum at the wellhead of conventional ISVE remediation systems is directly related to the range of influence (ROI) at the well and, therefore, the rate of removal of VOC's from the site. In addition, it is well known that the spacing of the wells between one another of conventional ISVE remediation systems is critical to the overall performance of the ISVE remediation system. This is due, in part, because the ROI can vary depending on the soil type and depth of groundwater. For example, Malot and Wood applied a ISVE remediation system. at a site in which 15,000 gallons of CCl 4 was spilled in an area where the top of the unconfined aquifer was 300 feet below the surface. Slotted pipes were installed at depths of 75 to 180 feet. A vacuum of 29.9 inches of Hg and a flow rate of 240 CFM was applied. After 90 days the vacuum stabilized at a ROI of 10 feet (Malot, James J. and Wood, P. R., "Low Cost, Site Specific, Total Approach to Decontamination", Conference on Environmental and Public Health Effects of Soils Contaminated with Petroleum Products, University of Massachusetts, Amherst, MA. Oct. 30-31, 1985). U.S. Pat. Nos. 4,593,760 and Re. 33,102 (U.S. Pat. No. 4,660,639), issued to Visser et al., describe one ISVE remediation system for removing VOC's from the vadose zone. Wells are sunk vertically into the vadose zone. The well casing includes a lower perforated region. VOC's in the vadose layer enter the perforated casing and are pumped to the surface for treatment. U.S. Pat. No. 4,832,122, issued to Corey et al., also describes another ISVE remediation system for removing VOC's from the vadose zone. Two sets of wells are sunk into the vadose zone. One well injects a fluid into the saturated zone below the plume of contamination. A second well, located above the plume, collects the fluid along with the VOC's from the plume, and pumps it to the surface for treatment. ISVE remediation systems can have a great degree of success removing VOC constituents exhibiting relatively high vapor pressures and under the proper hydrogeologic settings. In addition, ISVE remediation systems are very cost competitive when compared with other alternatives, including physical removal and disposal in a secure landfill. However, conventional ISVE remediation systems perform poorly for areas having relatively high water tables and/or soils with an extremely high clay content. It has thus become desirable to develop an improved ISVE remediation system for VOC contaminants which is more cost effective than a conventional ISVE remediation systems while, at the same time, eliminating the prior art problems of poor performance in areas having relatively high water tables due to high water lift and/or soils with an extremely high clay content. In addition, the improved ISVE remediation system should have a ROI at least equal or greater than a conventional ISVE remediation system and be less dependent on spacing between adjacent wells. SUMMARY OF THE INVENTION The present invention is directed to a system for recovering VOC contaminants from a surface or subsurface release. In one embodiment, the invention includes at least one horizontal trench having a perforated casing laid therein. One end of the casing is attached to a vacuum pump by means of a vertical riser. Clean stone is laid over the pipe to form an elongated collector and the surface of the trench is capped to minimize surface air and water infiltration. A suitable vacuum is applied and the VOC contaminates migrate first into the stone within the trench and then into the horizontal casing(s). The VOC contaminants move along the casings and up the vertical riser into a suitable container or directly discharged into the air. In a second embodiment, intermediate ones of the horizontal trenches are pressurized either by air or liquid fluids in either a heated or unheated state to improve the rate of migration of the VOC contaminates into the other alternating ISVE trenches exerting a negative pressure. In a third embodiment, vertical wells are used as the source of the pressurized fluid in place of the intermediate horizontal trenches. Accordingly, one aspect of the present invention is to provide a system for removing volatile contaminates from the vadose zone of a contaminated area. The system includes: (a) an elongated trench, having a pair of downwardly extending walls and a bottom, adjacent to the contaminated area; (b) a first conduit positioned within the trench, the conduit having a perforated portion for receiving the volatile contaminates; (c) a second conduit connected to the first conduit, the second conduit having a imperforate portion for conducting the volatile contaminates from the first conduit to the surface of the trench; (d) at least the lower portion of the trench adjacent to the contaminated area filled with a permeable fill material, the permeable fill material permitting the volatile contaminates to flow from the contaminated area adjacent to the trench into the first conduit; (e) sealing means upon the upper portion of the trench for preventing the entry air or other fluids from the surface of the trench into the permeable fill material; and (f) pump means connected to the second conduit for pumping the volatile contaminates from the vadose zone, through at least on of the side walls of the trench and the permeable fill material, into the first conduit, and through the second conduit to the surface of the trench. Another aspect of the present invention is to provide a collector for a system for removing volatile contaminates from the vadose zone of a contaminated area. The collector includes: (a) an elongated trench, having a pair of downwardly extending walls and a bottom, adjacent to the contaminated area; (b) a first conduit positioned within the trench, the conduit having a perforated portion for receiving the volatile contaminates; (c) a second conduit connected to the first conduit, the second conduit having a imperforate portion for conducting the volatile contaminates from the first conduit to the surface of the trench; (d) at least the lower portion of the trench adjacent to the contaminated area filled with a permeable fill material, the permeable fill material permitting the volatile contaminates to flow from the contaminated area adjacent to the trench into the first conduit; and (e) sealing means upon the upper portion of the trench for preventing the entry air or other fluids from the surface of the trench into the permeable fill material. Still another aspect of the present invention is to provide a system for removing volatile contaminates from the vadose zone of a contaminated area. The system includes: (a) an elongated trench, having a pair of downwardly extending walls and a bottom, adjacent to the contaminated area; (b) a first conduit positioned within the trench, the conduit having a perforated portion for receiving the volatile contaminates; (c) a second conduit connected to the first conduit, the second conduit having a imperforate portion for conducting the volatile contaminates from the first conduit to the surface of the trench; (d) at least the lower portion of the trench adjacent to the contaminated area filled with a permeable fill material, the permeable fill material permitting the volatile contaminates to flow from the contaminated area adjacent to the trench into the first conduit; (e) sealing means upon the upper portion of the trench for preventing the entry air or other fluids from the surface of the trench into the permeable fill material; (f) pump means connected to the second conduit for pumping the volatile contaminates from the vadose zone, through at least one of the side walls of the trench and the permeable fill material, into the first conduit, and through the second conduit to the surface of the trench; and (g) a third conduit positioned adjacent to the trench, the conduit having a perforated portion for supplying a fluid; (h) a fourth conduit connected to the third conduit, the fourth conduit having a imperforate portion for conducting the fluid from the surface of the trench to the third conduit; and (i) second pump means connected to the fourth conduit for pumping the fluid from surface of the trench, through the fourth conduit, into the third conduit, through the permeable fill material and at least one of the side walls of the trench, and the vadose zone, whereby the fluid from the second pump means is drawn across the contaminated area by the pump means so that the volatile contaminates are carried with the fluid to the surface. These and other aspects of the present invention will become apparent to those skilled in the art after a reading of the following description of the preferred embodiment when considered with the drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of an industrial site employing ISVE systems constructed according to the present invention; FIG. 2 is a plan view of the SET system shown in FIG. 1 at AREA 5, the view being generally diagrammatic; FIG. 3 is an enlarged cross-sectional view of the SET system shown in FIG. 2, taken along line 3-3; FIG. 4 is an enlarged cross-sectional view of the SET system shown in FIG. 3, taken along line 4--4; and FIG. 5 is an enlarged cross-sectional view of an alternative embodiment of the SET system shown in FIGS. 2-4. DESCRIPTION OF THE PREFERRED EMBODIMENT In the following description, like reference characters designate like or corresponding parts throughout the several views. Also in the following description, it is to be understood that such terms as "forward", "rearward", "left", "right", "upwardly", "downwardly", and the like are words of convenience and are not to be construed as limiting terms. Referring now to the drawings in general and to FIG. 1 in particular, it will be understood that the illustrations are for the purpose of describing a preferred embodiment of the invention and are not intended to limit the invention thereto. As best seen in FIG. 1, an industrial site, generally designated 10 and employing ISVE remediation systems 12, 14 and 16 constructed according to the present invention, is shown. Each of these systems has a different lay out depending on the site specific hydrogeologic and surface conditions. FIG. 2 is a plan view of the slotted extraction trench (SET) system 12 shown in FIG. 1 at AREA 5, the view being generally diagrammatic. The primary element of the SET remediation system 12 is the trench 20 itself. The trench 20 of the present invention is first excavated by backhoe. The overall dimensions of the trench 20 were 160 feet long by 15 feet deep. The width of the trench 20 was approximately 18 inches. A 4 inch diameter PVC slotted pipe 22 (not shown) is laid in the bottom of trench 20. A vertical riser 24 of schedule 40 PVC pipe is connected to the 4 inch diameter slotted pipe 20 near its midportion 26. An oil-less type vacuum pump 30 is connected at the riser 24 by means of conduit 32 for creating a source of negative air pressure. Control of the air flow entering the vacuum pump is by a relief valve 34. The relief valve 34 operates by allowing excess ambient air to enter the vacuum pump 30 in order that the desired negative pressure for the trench 20 can be maintained. A pressure gauge 36 located adjacent to the vacuum pump provides a measurement of the negative pressure at the pump. The discharge 40 from the vacuum pump may be connected to a suitable sub-system (not shown) for collecting, treating, or disposing of the VOC's. For example, the gas may be collected in a storage tank. The volatile gases also may be discharged into the atmosphere where environmental constraints permit, adsorbed by activated charcoal, or destroyed by incineration. An exhaust emission and monitoring sub-system (not shown) measures the VOC's on a periodic basis. The periodic measurements of VOC concentration and air velocity at system discharge versus time are used to calculate the total pounds per day of VOC's. The current limit of total VOC per day is dependent on the location of the contaminated site. Secondary means for disposal of VOC's greater than permissible limits include the aforementioned carbon adsorption and incineration. Several "nests" of vacuum monitoring wells 50 are placed at specific distances and depths with respect to the trench 20 to monitor the ROI of the SET system in the surrounding soil. Each nest includes several monitors 52 each at different depths to measure the pressure differential with respect to adjacent zones. Each monitor 52 consists of a well which is capped at the surface and equipped with a pressure gauge which can be read periodically and used to determine the overall ROI of the SET system with respect to the dimensions of the VOC plume, thereby monitoring the effectiveness of the SET system. Turning to FIG. 3, there is shown an enlarged cross-sectional view of the SET system shown in FIG. 2, taken along line 3--3. A 6 inch layer of clean stone 60 having an average size of greater than 1/4 inches in diameter was placed at the bottom of the trench 20. The 4 inch diameter PVC slotted pipe 22 is laid upon the first layer of stone and the vertical riser 24 is connected to the 4 inch diameter slotted pipe 22 near its midportion. A geo-textile fabric 62 is laid over slotted pipe 22 to limit sand infiltration. A second layer of clean stone 60 is laid over the slotted pipe 22 to within 2-5 feet of the surface or to correspond to the depth of VOC contamination. As best seen in FIG. 4, a 6 mil polyethylene sheet 64 is laid over the second clean stone layer to minimize surface air and water from entering the trench. The final 2-5 feet of the trench 20 is filled with a mixture 66 of backfill and bentonite clay to form a water and air resistant cap above the trench. A concrete plug may be added where required for safety. The vacuum pump 30, preferable capable of about 320 CFM at 15 inches of Hg, is then connected to the pipe riser 24 leading to the horizontal slotted pipe 22 in the bottom of the trench 20. The ROI of the SET system 12 is measured by means of monitors 52. FIG. 5 is an enlarged cross-sectional view of an alternative embodiment of the SET system 12 shown in FIGS. 2 through 4. The primary element of the alternative remediation system is the trench 20 itself and a second trench 72 or vertical well (not shown) for injecting a heated fluid of air or liquid. Like the unassisted SET system 12, the second trench 72 of the alternative embodiment of the present invention is first excavated by backhoe. A 4 inch diameter PVC slotted pipe 74 is laid in the bottom of trench 72. A vertical riser 76 of schedule 40 PVC pipe is connected to the 4 inch diameter slotted pipe 74 near its midportion. An oil-less type fluid pump 80 is connected at the riser 76 for creating a source of positive air or liquid fluid pressure. A pressure gauge 82 located adjacent to the pump 80 provides a measurement of the pressure at the pump. Like the unassisted SET system 12, several "nests" of vacuum monitoring wells 50 are placed at specific distances and depths with respect to the trench 20 to monitor the ROI of the SET system in the surrounding soil. Each nest includes several monitors 52 each at different depths to measure the pressure differential with respect to adjacent zones. The method and apparatus according to the present invention will become more apparent upon reviewing the following detailed examples. EXAMPLE NO. 1 A 4 inch diameter well was installed to a depth of 15 feet at AREA 1. Slotted PVC pipe was utilized for the bottom 12 feet of the well. A 1 1/2 hp vacuum pump capable of 13 CFM at 10 inches of Hg was connected to the well head. The ROI of the well was measured to be 10 feet (314 ft 2 ). Based on the initial ROI data, twelve additional wells were installed in order to provide coverage for an area of approximately 80 feet by 80 feet (6400 ft 2 ). A second vacuum pump capable of 320 CFM at 15 inches of Hg was then connected to a piping manifold leading to each of the twelve wells. Air flow from well was measured and varied from between about 14 CFM to about 24 CFM. The effectiveness at the well head of the 4 inch diameter wells was calculated (CFM/2*pi*r*d) based upon a 9 inch diameter bore, 12 feet of effective depth, and a maximum of 24 CFM at 15 inches of Hg to be 0.85 CFM/ft 2 of vertical surface area at the well head. Similarly, the effectiveness at the ROI of the 4 inch diameter wells was calculated (CFM/2*pi*r*d) based upon a 10 feet radius ROI, 12 feet of effective depth, and a maximum of 24 CFM at 15 inches of Hg to be 0.032 CFM/ft 2 of vertical surface area at the ROI. Finally, the surface area effectiveness at the ROI of the 4 inch diameter wells was calculated (pi*r 2 /CFM*d) based upon the 10 feet radius ROI, 12 feet of effective depth, and a maximum of 24 CFM at 15 inches of Hg to be 1.09 ft 2 /CFM/ft of horizontal surface area at the ROI. Utilizing standard EPA cost estimates, such as set out in EPA report EPA 540 A-89-003 (July 1989), the installed cost of this vertical well ISVE system, excluding pumps, should be about $8000. EXAMPLE NO. 2 A slotted extraction trench (SET) was excavated by backhoe in AREA 5. The overall dimensions of the SET were 160 feet long by 15 feet deep. The width of the trench was approximately 18 inches. A 6 inch layer of clean stone having an average size of greater than 1/4 inches in diameter was placed at the bottom of the SET. A 4 inch diameter PVC slotted pipe was laid upon the first layer of stone. A vertical riser of schedule 40 PVC pipe was connected to the 4 inch diameter slotted pipe near its midportion. A geo-textile fabric was laid over the slotted pipe to limit sand infiltration. A second layer of clean stone was laid over the slotted pipe to within 2 1/2 feet of the surface. A 6 mil polyethylene sheet was laid over the second clean stone layer to prevent surface air and water from entering the SET. The final 2 1/2 feet of the SET was filled with a mixture of backfill and bentonite clay to form a water and air resistant cap above the SET. A vacuum pump capable of about 320 CFM at 15 inches of Hg was then connected to the pipe riser leading to the horizontal slotted pipe in the bottom of the SET. Air flow was measured and found to be about 320 CFM at only 5 inches of Hg. Estimated CFM at 15 inches of Hg was calculated to be about 600 CFM (CFM =k * (difference in pressure (psi 1/2 )). The ROI of the well was measured to be 30 feet on either side of the SET (9600 ft 2 ). The effectiveness at the trench surface of the SET was calculated (CFM/2dL) based upon a 160 foot length, 12 1/2 feet of effective depth, and a maximum of 320 CFM at 5 inches of Hg to be 0.08 CFM/ft 2 of vertical surface area at the trench surface. At 15 inches of Hg, the effectiveness at the trench surface was estimated to be about 0.8 CFM/ft 2 which is comparable to the vertical well ISVE system in Example 1. Similarly, the effectiveness at the ROI of the SET was calculated (CFM/2dL) based upon a 160 foot length, 12 1/2 feet of effective depth, and a maximum of 320 CFM at 5 inches of Hg to be 0.08 CFM/ft 2 of vertical surface area at the ROI. This value is approximately twice the value of the vertical well ISVE system in Example 1 at 10 inches of Hg less than in Example 1. Finally, the surface area effectiveness at the ROI of the SET was calculated (2rL/CFM*d) based upon the 30 feet range ROI, a 160 foot length, 12 1/2 feet of effective depth, and a maximum of 320 CFM at 5 inches of Hg to be 2.4 ft 2 /CFM/ft of horizontal surface area at the ROI. Utilizing standard EPA cost estimates, such as set out in EPA report EPA 540 A-89-003 (July 1989), the installed cost of this SET ISVE system, excluding pumps, should be about $4000. EXAMPLE NO 3 Based on the results for AREAS 1 and 5, above, AREA 1 was retrofitted with a SET system. Three slotted extraction trenches (SET) were excavated by backhoe. The first two SETs were perpendicular to and bisected by the third SET. The overall dimensions of each of the first two SETs were 40 feet long by 15 feet deep. The third SET was 80 feet long by 15 feet deep. The total overall length of the SET system was 160 feet. The width of the trenches were approximately 18 inches. A 6 inch layer of clean stone having an average size of greater than 1/4 inches in diameter was placed at the bottom of the SETs. A 4 inch diameter PVC slotted pipe was laid upon the first layer of stone. A vertical riser of schedule 40 PVC pipe was connected to the 4 inch diameter slotted pipes near its midportion. A geo-textile fabric was laid over the slotted pipe to limit sand infiltration. A second layer of clean stone was laid over the slotted pipe to within 2 1/2 feet of the surface. A 6 mil polyethylene sheet was laid over the second clean stone layer to prevent surface air and feet of the SET. The final 2 1/2 water from entering the SET. The final 2 1/2 feet of the SET was filled with a mixture of backfill and bentonite clay to form a water and air resistant cap above the SET. A vacuum pump capable of about 320 CFM at 15 inches of Hg was then connected to the pipe riser leading to the horizontal slotted pipe in the bottom of the SET. Air flow was measured and found to be about 320 CFM at only 5 inches of Hg. The ROI of the well was measured to be 30 feet on either side of the SET (9600 ft 2 ). The effectiveness at the trench surface of the SET was calculated (CFM/2dL) based upon a 160 foot length, 12 1/2 feet of effective depth, and a maximum of 320 CFM at 5 inches of Hg to be 0.08 CFM/ft of vertical surface area at the trench surface. At 15 inches of Hg, the effectiveness at the trench surface was estimated to be about 0.8 CFM/ft 2 which was comparable to the original vertical well ISVE system for AREA 1 as discussed in Example 1. Similarly, the effectiveness at the ROI of the SET was calculated (CFM/2dL) based upon a 160 foot length, 12 1/2 feet of effective depth, and a maximum of 320 CFM at 5 inches of Hg to be 0.08 CFM/ft 2 of vertical surface area at the ROI. This value is approximately twice the value of the vertical well ISVE system in Example 1 at 10 inches of Hg less than in Example 1. Finally, the surface area effectiveness at the ROI of the SET was calculated (2rL/CFM*d) based upon the 30 feet range ROI, a 160 foot length, 12 1/2 feet of effective depth, and a maximum of 320 CFM at 5 inches of Hg to be 2.4 ft 2 /CFM/ft of horizontal surface area at the ROI. Utilizing standard EPA cost estimates, such as set out in EPA report EPA 540 A-89-003 (July 1989), the installed cost of this SET ISVE system, excluding pumps, was estimated to be about $2000, or one fourth of the installed cost of the original vertical well ISVE system. EXAMPLE NO. 4 Based on the results for AREAS 1 and 5, above, a third area was fitted with a SET system. A single slotted extraction trench (SET) was excavated by backhoe. The SET was 30 feet long by 14 feet deep. The width of the trenches were approximately 18 inches. A 6 inch layer of clean stone having an average size of greater than 1/4 inches in diameter was placed at the bottom of the SET. A 4 inch diameter PVC slotted pipe was laid upon the first layer of stone. A vertical riser of schedule 40 PVC pipe was connected to the 4 inch diameter slotted pipes near its midportion. A geo-textile fabric was laid over the slotted pipe to limit sand infiltration. A second layer of clean stone was laid over the slotted pipe to within 5 feet of the surface. A 6 mil polyethylene sheet was laid over the second clean stone layer to prevent surface air and water from entering the SET. The final 5 feet of the SET was filled with a mixture of backfill and bentonite clay to form a water and air resistant cap above the SET. A vacuum pump capable of about 50 CFM at 15 inches of Hg was then connected to the pipe riser leading to the horizontal slotted pipe in the bottom of the SET. Air flow was measured and found to be about 46 CFM at only 5 inches of Hg. The ROI of the well was measured to be 30 feet on either side of the SET (2400 ft 2 ). The effectiveness at the trench surface of the SET was calculated (CFM/2dL) based upon a 30 foot length, 9 feet of effective depth, and a maximum of 46 CFM at 5 inches of Hg to be 0.08 CFM/ft 2 of vertical surface area at the trench surface. At 15 inches of Hg, the effectiveness at the trench surface was estimated to be about 0.8 CFM/ft 2 which was comparable to the original vertical well ISVE system for AREA 1 as discussed in Example 1. Similarly, the effectiveness at the ROI of the SET was calculated (CFM/2dL) based upon a 30 foot length, 9 feet of effective depth, and a maximum of 46 CFM at 5 inches of Hg to be 0.08 CFM/ft 2 of vertical surface area at the ROI. This value is approximately twice the value of the vertical well ISVE system in Example 1 and at 10 inches of Hg less than in Example 1. Finally, the surface area effectiveness at the ROI of the SET was calculated (2rL/CFM*d) based upon the 30 feet range ROI, a 30 foot length, 9 feet of effective depth, and a maximum of 46 CFM at 5 inches of Hg to be 4.3 ft 2 /CFM/ft of horizontal surface area at the ROI. From the above Examples it is clear that at depths less than 20 feet the SET ISVE system is more effective, more economical to install, achieves faster remediation than a vertical well ISVE. In addition, the high efficiency of the SET ISVE system allows high CFM operation at lower vacuums levels which provides less lift to the ground water, thereby resulting in less waste water entering the vacuum extraction system. The trench design of the SET ISVE system does not require the high degree of "lapping" required by a vertical well ISVE to provide complete coverage of the contaminated area. Moreover, the seal design of the SET ISVE system minimizes "short circuiting" by surface air and infiltration of surface water. Finally, the combination of the clean stone fill material and the geo-textile fabric around the perforated conduit minimizes plugging by soil infiltration. In the above Examples, the present invention was directed to removal of VOC's from the vadose zone. However, the present invention also may be used in combination with a system for removing contaminates from contaminated groundwater adjacent to the vadose zone. Thus, one or more pumps can be added to remove groundwater from the aquifer, treat it to remove the contaminates, and return it to the aquifer. Certain other modifications and improvements will occur to those skilled in the art upon reading of the foregoing description. By way of example, while the SET ISVE system of the present invention has been shown laid out in straight line or criss-cross arrangements, other geometries including serpentine and spiral configurations could be equally desirable, particularly when the contours of the surface and the VOC contaminate plumes are not linear. It should be understood that all such modifications and improvements have been deleted herein for the sake of conciseness and readability but are properly within the scope of the following claims.

A system for recovering VOC contaminants from a surface or subsurface release. In one embodiment, the invention includes at least one horizontal trench having a perforated casing laid therein. One end of the casing is attached to a vacuum pump by means of a vertical riser. Clean stone is laid over the pipe to form an elongated collector and the surface of the trench is capped to minimize surface air and water infiltration. A suitable vacuum is applied and the VOC contaminates migrate first into the stone within the trench and then into the horizontal casing(s). The VOC contaminants move along the casings and up the vertical riser into a suitable container or directly discharged into the air. In a second embodiment, intermediate ones of the horizontal trenches are pressurized either by air or liquid fluids in either a heated or unheated state to improve the rate of migration of the VOC contaminates into the other alternating ISVE trenches exerting a negative pressure. In a third embodiment, vertical wells are used as the source of the pressurized fluid in place of the intermediate horizontal trenches.

[0001] This application claims priority from European Patent Application No. 04 000 081.2, which was filed on Jan. 6, 2004. TECHNICAL FIELD OF THE INVENTION [0002] The present invention relates to a programme-controlled unit comprising a crossbar comprising a multiplicity of ports, a multiplicity of devices which are connected to the ports of the crossbar and can exchange data via the crossbar, and debug resources for detecting the events and states occurring in the programme-controlled unit. DESCRIPTION OF PRIOR ART [0003] Programme-controlled units are understood to be devices executing software programmes such as, for example, microcontrollers, microprocessors, signal processors etc. [0004] The basic configuration of a programme-controlled unit is shown in FIG. 3 . FIG. 3 shows a microcontroller. For the sake of completeness, it shall be noted at this point that only the components of the microcontroller are shown and described which are of particular interest in the present text. [0005] In the microcontroller shown in FIG. 3 contains a bust 301 , devices 302 - 1 to 302 -n connected to one another via the bus and debug resources 303 , also connected to the bus 301 , the debug resources 303 consisting of a monitoring device 304 and a control device 305 . [0006] Of the microcontroller components mentioned, the device 302 - 1 is a first CPU, the device 302 - 2 is a second CPU, the device 302 -n- 1 is a storage device and the device 302 -n is an I/O controller. Naturally, the devices 302 - 1 , 302 - 2 , 302 -n- 1 and 302 -n can also be formed by any other microcontroller components. In addition, a multiplicity of arbitrary other microcontroller components such as, for example, other CPUs, storage devices and/or other peripheral units such as, for example, analogue/digital converters, digital/analogue converters, timers, DMA controllers etc. are usually connected to the bus 301 . [0007] The devices 302 - 1 to 302 -n can exchange data via the bus 301 . For example: the CPUs 302 - 1 and 302 - 2 can transmit data to the storage device 302 -n- 1 and/or read data from the storage device 302 -n- 1 via the bus 301 , the first CPU 302 - 1 can transmit data, which are to be output from the microcontroller by the I/O controller 302 -n, to the I/O controller via the bus 301 , or the second CPU 302 - 2 can read data from the microcontroller which were received by the I/O controller 302 -n from outside the microcontroller via the bus 301 , etc. [0011] The debug resources 303 or, more precisely, their monitoring device 304 , tracks the addresses, data and control signals transmitted via the bus 301 and forwards selected addresses, data and/or control signals to the control device 305 . The control device 305 outputs the addresses, data and/or control signals supplied to it to an external control and evaluating device, not shown in FIG. 3 , provided outside the microcontroller, or provides them for being fetched by the external control and evaluating device. The external control and evaluating device evaluates the addresses, data and/or control signals supplied to it and called trace data and, during this process, can detect errors occurring in the microcontroller and their cause. The external control and evaluating device also instructs the control device 305 about the prerequisites under which addresses, data and/or control signals are to be output to the external control and evaluating device. The control device 305 performs corresponding filtering of the data supplied to it by the monitoring device 304 and/or causes the monitoring device 304 to forward only particular addresses, data and/or control signals, and/or addresses, data and/or control signals only on the occurrence of particular states or events, to the control device 305 . In addition, the control device 305 can be capable of processing the data supplied to it by the monitoring device 304 before they are forwarded to the external control and evaluating device, particularly of coding or compressing the data to be forwarded or of packaging the data to be forwarded into messages having a predetermined format, or of transmitting the data together with other data, for example together with time information representing the time of data acquisition or with sequence information representing the sequence of data acquisition, to the external control and evaluating device. [0012] The debug resources 303 are formed by an on-chip debug support module (OCDS module) or a part of an OCDS module. Reference is made to DE 101 19 266 A1 with respect to further details relating to debug resources configured and operating as described. [0013] It is particularly due to the ever increasing clock frequencies with which microcontrollers and other programme-controlled units are operating, and due to the ever increasing number of microcontroller components which must be connected to one another via the bus, that it is becoming increasingly more difficult to transmit via the bus 301 the data which are to be transmitted between the microcontroller components connected to the bus. [0014] In the meantime, therefore, it has been decided to connect at least certain microcontroller components to one another via a crossbar. [0015] FIG. 4 shows an arrangement in which the first CPU 302 - 1 , the second CPU 302 - 2 , the storage device 302 -n- 1 and the I/O controller 302 -n are connected to one another via a crossbar. The arrangement shown in FIG. 4 contains a crossbar 410 and the above-mentioned devices 302 - 1 , 302 - 2 , 302 -n- 1 , 302 -n. The crossbar 410 contains four ports designated by the reference symbols 411 , 412 , 413 and 414 , one of the devices to be connected to one another via the crossbar being connected to each port. In the example considered, the first CPU 302 - 1 is connected to the first port 411 , the second CPU 302 - 2 is connected to the second port 412 , the storage device 302 -n- 1 is connected to the third port 413 and the I/O controller 302 -n is connected to the fourth port 414 . The crossbar 410 has in its interior configurable paths via which each device which could become bus master at bus 301 , that is to say the first CPU 302 - 1 and the second CPU 302 - 2 in the example considered, can be connected to each of the other devices in each case. Crossbars can be constructed in such a manner that at the same time a number of different connections exist between the devices connected thereto so that, for example, the first CPU 302 - 1 can transmit data to the storage device 302 -n- 1 and, at the same time, the second CPU 302 - 2 can read data from the I/O controller 302 - 10 . By this means, data which are to be transmitted between the devices connected to the crossbar 410 can be transmitted more rapidly, more precisely with less delay, on average than is the case with devices connected to one another via a bus. [0016] With such an arrangement, however, greater effort is associated with tracing and evaluating the addresses, data and/or control signals which are transmitted between the devices connected to the crossbar 310 . This is because, in this case, a total of four buses must be monitored, specifically the bus between the first CPU 302 - 1 and the first port 411 , the bus between the second CPU 302 - 2 and the second port 412 , the bus between the storage device 302 -n- 1 and the third port 413 , and the bus between the I/O controller 302 -n and the fourth port 414 . To trace and evaluate addresses, data and/or control signals transmitted via a number of different buses, the debug resources 303 must be connected to all buses, or a number of debug resources of the type of debug resources 303 corresponding to the number of buses must be provided. It can be seen, that both are associated with much greater effort than tracing and evaluating the addresses, data and/or control signals which are transmitted via the bus 301 of the arrangement shown in FIG. 3 . SUMMARY OF THE INVENTION [0017] The present invention has the object, therefore, of finding a possibility by means of which the addresses, data and/or control signals transmitted between devices connected to one another via a crossbar can be traced and evaluated by using debug resources of simple configuration and operating mode. [0018] According to the invention, this object can be achieved by a programme-controlled unit comprising a crossbar with a multiplicity of ports, a multiplicity of devices which are connected to the ports of the crossbar and can exchange data via the crossbar, and debug resources for detecting the events and states occurring in the programme-controlled unit, wherein the ports of the crossbar comprise a diagnostic port, wherein the addresses, data and/or control signals which are transmitted between two other ports of the crossbar are additionally also supplied to the diagnostic port, and wherein the debug resources are connected to the diagnostic port of the crossbar. [0019] It may be provided that no addresses, data and/or control signals can be transmitted to one of the devices connected to the other ports via the diagnostic port. It may further be provided that the device connected to the diagnostic port cannot be addressed by any of the other devices which are connected to the other ports of the crossbar. The diagnostic port can be connected to at least two other ports of the crossbar via internal lines or buses. The diagnostic port can be connected via internal lines or buses to all other ports of the crossbar to which master devices are connected. The diagnostic port can be connected via internal lines or buses to all other ports of the crossbar to which slave devices are connected. The diagnostic port may contain a multiplexer by means of the drive to which it can be determined which of the addresses, data and/or control signals transmitted via the crossbar are output from the diagnostic port. The multiplexer can be controlled by the debug resources, and a control and evaluating device provided outside the programme-controlled unit may instruct the debug resources on how they have to behave. The multiplexer can be controlled by a control and evaluating device provided outside the programme-controlled unit. The multiplexer can be controlled by the crossbar. The multiplexer can be brought into a state predetermined from outside the programme-controlled unit and can be permanently held in this state. It can be monitored which of the devices connected to the crossbar transmit addresses, data and/or control signals to which other ones of the devices connected to the crossbar, and the multiplexer can be automatically driven or switched in each case in such a manner that all addresses, data and control signals transmitted from and to a particular one of the devices connected to the crossbar are output via the diagnostic port. The multiplexer can first be brought into a predetermined state, and the multiplexer can automatically be brought into a predetermined other state if a particular event has occurred outside the crossbar. The particular event may consist in that the addresses, data and/or control signals output from the diagnostic port meet a predetermined condition. The multiplexer can be automatically switched if a particular event occurs inside the crossbar. The particular event may consist in that an error detection device contained in one of the ports has detected the occurrence of an error, and in that, following the detection of the error, the multiplexer is switched in such a manner that the addresses, data and/or control signals transmitted via the port containing the relevant error detection device are output from the diagnostic port. Priorities are allocated to all possible internal connections between the ports of the crossbar, and the multiplexer can automatically be switched in such a manner that the addresses, data and/or control signals output from the diagnostic port are in each case those addresses, data and/or control signals which are transmitted via the connection to which the highest priority is allocated. The debug resources may contain a control and preprocessing device which delays the addresses, data and/or control signals output from the diagnostic port, before they are forwarded, by a different amount in such a manner that different amounts of delay of the addresses, data and/or control signals through the crossbar are compensated for, and the addresses, data and/or control signals simultaneously output from the control and preprocessing device are always associated addresses, data and/or control signals. The debug resources can cause certain components of the crossbar, via the diagnostic port and additional internal lines of the crossbar, to output information stored in the relevant components, and the multiplexer can be driven in such a manner that this information is output from the crossbar via the diagnostic port. The debug resources can be connected to devices connected to the crossbar via additional lines and, via these lines, the relevant devices can be caused to output information stored in the relevant devices to the bus connecting the relevant device to the crossbar, and wherein the multiplexer is driven in such a manner that this information is output from the crossbar via the diagnostic port. [0020] The programme-controlled unit according to the invention is characterized by the fact that the ports of the crossbar comprise a diagnostic port, that the addresses, data and/or control signals which are transmitted between two other ports of the crossbar are additionally also supplied to the diagnostic port, and that the debug resources are connected to the diagnostic port of the crossbar. [0024] In such a programme-controlled unit, it is not necessary to provide a number of debug resources nor is it necessary to connect the debug resources to all buses via which the devices connected to the crossbar are connected to the crossbar. [0025] Thus, the addresses, data and/or control signals transmitted between devices connected to one another via a crossbar can be traced and evaluated by using debug resources of simple configuration and operating mode. [0026] Advantageous developments of the invention can be found in the description following and the figures. BRIEF DESCRIPTION OF THE DRAWINGS [0027] The invention will be described in greater detail by means of illustrative embodiments and reference to the figures, in which: [0028] FIG. 1 shows a first illustrative embodiment of the programme-controlled unit presented here, [0029] FIG. 2 shows a second illustrative embodiment of the programme-controlled unit presented here, [0030] FIG. 3 shows a conventional programme-controlled unit in which devices to be connected to one another are connected to one another via a bus, and [0031] FIG. 4 shows a conventional programme-controlled unit in which devices to be connected to one another are connected to one another via a crossbar. DESCRIPTION OF PREFERRED EMBODIMENTS [0032] The programme-controlled units described in the text which follows are microcontrollers. However, there could also be other devices executing programmes such as, for example, microprocessors, signal processors etc. [0033] It should be noted even at this early point that only the components of the microcontrollers of particular interest in the present text are shown in FIGS. 1 and 2 and described. [0034] The microcontrollers presented here are microcontrollers in which the components to be connected to one another, such as CPU, memory, I/O controller etc. are at least partially connected to one another via a crossbar. Thus, they are microcontrollers of the type shown in FIG. 4 . However, in the case of the microcontrollers presented here, it is possible to trace the addresses, data and/or control signals transmitted between the devices connected to the crossbar by means of debug resources of simple configuration and operating mode. [0035] The arrangement shown in FIG. 1 comprises a crossbar 110 , devices 102 - 1 , 102 - 2 , 102 -n- 1 and 102 -n connected to one another via the crossbar 110 , and debug resources 120 . [0036] Of the devices 102 - 1 , 102 - 2 , 102 -n- 1 and 102 -n, the device 102 - 1 is a first CPU, the device 102 - 2 is a second CPU, the device 102 -n- 1 is a storage device and the device 102 -n is an I/O controller. The said devices correspond to the devices 302 - 1 , 302 - 2 , 302 -n- 1 and 302 -n of the arrangements shown in FIGS. 3 and 4 . For the sake of completeness, it should be noted at this point that the devices 102 - 1 , 102 - 2 , 102 -n- 1 and 102 -n could also be formed by any other microcontroller components. In the example considered, the devices 102 - 1 and 102 - 2 are master devices corresponding to a bus master, and the devices 102 -n- 1 and 102 -n are slave devices corresponding to a bus slave. [0037] The crossbar 110 contains ports designated by the reference symbols 111 , 112 , 113 and 114 , one of the devices to be connected to one another via the crossbar 110 being connected to each port. In the example considered, the first CPU 102 - 1 is connected to the first port 111 , the second CPU 102 - 2 is connected to the second port 112 , the storage device 102 -n- 1 is connected to the third port 113 and the I/O controller 102 -n is connected to the fourth port 114 . The crossbar 110 has in its interior configurable paths, not shown in FIG. 1 , via which each master device, that is to say the first CPU 102 - 1 and the second CPU 102 - 2 in the example considered, can be connected to each of the other devices in each case. In addition, the crossbar 110 contains a control device, also not shown in FIG. 1 , which ensures by a corresponding configuration of the configurable paths that devices in each case to be connected to one another are connected to one another. More precisely, a master device which wants to transmit data to another device or to read data from the other devices transmits to the crossbar an address associated with the other device, and the control device recognizes from this address the device with which the relevant master device wishes to communicate, and then establishes a connection between the relevant master device and the other device specified by the address. [0038] In addition, the crossbar 110 contains a fifth port 115 , designated as diagnostic port in the text which follows, to which the debug resources 120 are connected. Via the diagnostic port 115 , it is possible only to read data from the crossbar 110 but not to transmit data to one of the other devices 102 - 1 , 102 - 2 , 102 -n- 1 and 102 -n which are connected to the crossbar 110 . In addition, the diagnostic port 115 or the debug resources 125 connected thereto, respectively, cannot be addressed by one of the master devices. That is to say, the debug resources 120 can neither output data to another one of the devices connected to the crossbar 110 nor be addressed by one of these other devices. [0039] In the example considered, the diagnostic port 115 is connected via lines or buses 116 and 117 to the ports to which master devices are connected. More precisely, the diagnostic port 115 is connected via a line or a bus 116 to the first port 111 , and via a line or a bus 117 to the second port 112 . Via the diagnostic port 115 , the addresses, data and/or control signals which are transmitted from and to the device connected to the first port 111 via the crossbar 110 , and/or are transmitted from and to the device connected to the second port 112 , are output to the debug resources 120 . In the diagnostic port 115 , a multiplexer, not shown in FIG. 1 , is provided by means of which optionally either the data transmitted via the first port 111 or the data transmitted via the second port 112 are switched through to the debug resources 120 . [0040] The debug resources 120 consist of a control and monitoring device 103 and a control and preprocessing device 121 . [0041] The addresses, data and/or control signals output from the diagnostic port 115 to the debug resources 120 initially pass to the control and preprocessing device 121 and are forwarded by the latter, after any processing which may be required, to the control and monitoring device 103 . [0042] The control and monitoring device 103 corresponds to the debug resources 303 of the arrangement according to FIG. 3 . That is to say, it selects particular addresses, data and/or control signals from the addresses, data and/or control signals supplied to it and forwards them as trace data to an external control and evaluating device provided outside the microcontroller. With regard to other details on the configuration and the operation of the control and monitoring device 103 , reference is made to the corresponding statements relating to the debug resources 303 . [0043] The preprocessing, performed by the control and preprocessing device 121 , of the addresses, data and/or control signals supplied to it from the crossbar 110 can comprise, for example, delaying the addresses, data and control signals by a different amount before forwarding them to the control and monitoring device 103 . This makes it possible to achieve that the addresses, data and control signals output from the control and preprocessing device 121 are always associated addresses, data and control signals. This is found to be advantageous because it may be that the addresses, data and control signals output from the diagnostic port 115 of the crossbar 110 are non-associated addresses, data and control signals. This is because, in general, for example, pipeline stages formed by registers are installed in the configurable paths between the ports 111 to 114 of the crossbar 110 , a different number of pipeline stages possibly being provided in the paths for transmitting the addresses, in the paths for transmitting the data and in the paths for transmitting the control signals. For example, it may be that the address path has two pipeline stages between the first port 111 and the third port 113 , and that the data path and the control signal path have three pipelines between the first port 111 and the third port 113 so that the addresses have less delay through the crossbar 110 than the data and the control signals. It could be provided in this case that when the addresses, data and control signals output from the diagnostic port 115 of the crossbar 110 are addresses, data and control signals transmitted from the storage device 102 -n- 1 to the first CPU 102 - 1 , the control and preprocessing device 121 forwards the addresses with a delay to the control and monitoring device 103 , and forwards the data and the control signals immediately to the control and monitoring device 103 , the duration of the delay in forwarding the addresses corresponding to the difference in the delays of the addresses, data and control signals through the crossbar. Consequently, the addresses, data and control signals simultaneously output from the control and preprocessing device 121 are always associated addresses, data and control signals. [0047] The control and preprocessing device 121 moreover controls the multiplexer contained in the diagnostic port 115 . How this is to be performed, more precisely how the multiplexer is to be driven under what preconditions, takes the form of instruction by the control and preprocessing device 121 , the control and monitoring device 103 in the example considered, which device for its part receives corresponding instructions from the external control and evaluation device. It may be remarked for the sake of completeness that the control and preprocessing device 121 could also be instructed on how it is to behave by another microcontroller component, or directly by the external control and evaluation device. The control of the control and preprocessing device 121 , and even the control of the multiplexer, can also be performed by signals transmitted via the crossbar, more precisely by control signals transmitted via so-called sideband lines. The multiplexer can also be controlled via the crossbar 110 . [0048] In the example considered, there are five different possibilities for driving the multiplexer. [0049] When the multiplexer is driven in accordance with the fifth possibility (jump event mode), priorities are allocated to all possible internal connections between the ports 111 to 114 , and the multiplexer is driven in such a manner that the addresses, data and control signals output from the diagnostic port are in each case the addresses, data and control signals transmitted via the connection which is allocated the highest priority. [0050] FIG. 2 shows a modified embodiment of the arrangement shown in FIG. 1 . [0051] The arrangement shown in FIG. 2 very largely corresponds to the arrangement shown in FIG. 1 . Components designated by the same reference symbols are identical or mutually corresponding components. The only difference is the ports of the crossbar 110 to which the diagnostic port 115 is connected. In the arrangement shown in FIG. 2 , the diagnostic port 115 is connected to the ports to which slave devices are connected. More precisely, the diagnostic port 115 is connected to the third port 113 via a line or a bus 118 , and to the fifth port 114 via a line or a bus 119 . Thus, the addresses, data and/or control signals transmitted via the crossbar 110 from and to the device connected to the third port 113 and/or transmitted from and to the device connected to the fifth port 114 can be output to the debug resources 120 via the diagnostic port 115 ; via the multiplexer contained in the diagnostic port 115 , either the addresses, data and/or control signals transmitted via the third port 113 , and/or the addresses, data and/or control signals transmitted via the fourth port 114 are optionally switched through to the debug resources 120 . [0052] The abovementioned differences require a modified drive to the multiplexer. In particular the first possibility for multiplexer control already explained above (static mode) is used when all addresses, data and/or control signals transmitted via the third port 113 are to be output via the diagnostic port 115 , or when all addresses, data and/or control signals transmitted via the fourth port 114 are to be output via the diagnostic port 115 , and the second possibility for multiplexer drive already explained above (dynamic mode) is used when all addresses, data and/or control signals transmitted via the first port 111 are to be output via the diagnostic port 115 , or when all addresses, data and/or control signals transmitted via the second port 112 are to be output via the diagnostic port 115 . [0055] For the rest, the arrangement shown in FIG. 2 operates like the arrangement shown in FIG. 1 . [0056] The arrangements described can be modified and expanded in many ways. [0057] For example, it is possible that the crossbar contains one or more further diagnostic ports. This is found to be advantageous because data transfers taking place simultaneously between various pairs of ports can be detected in this case. [0058] Independently of this, it could be provided that storage devices contained in the other ports, for example registers contained in the error detection devices and in which information on errors which have occurred or the states prevailing on the occurrence of an error such as, for example, the current configuration of the configurable paths is stored, are read out via the diagnostic port. This can be done by the debug resources causing particular components of the crossbar, via the diagnostic port and additional internal lines of the crossbar, to output information stored in the corresponding components, and by the multiplexer being driven in such a manner that this information is output from the crossbar via the diagnostic port. [0059] It could also be provided that the debug resources 120 are additionally connected to one, a number or all of the devices connected to the ports 111 to 114 via one or more separate lines, and that the debug resources 120 can cause the respective devices to output particular internal information to the bus connecting the relevant device to the crossbar via the additional lines. This information could then be detected by a corresponding multiplexer drive, output from the crossbar 110 via the diagnostic port 115 thereof, and evaluated by the external control and evaluating device. [0060] Independently of the details of their practical implementation, the arrangements described above are found to be extremely advantageous. They make it possible for the addresses, data and/or control signals transmitted between devices connected to one another via a crossbar to be traced and evaluated by using debug resources of simple configuration and operating mode.

A programme-controlled unit comprises a crossbar with a multiplicity of ports, a multiplicity of devices which are connected to the ports of the crossbar and can exchange data via the crossbar, and debug resources for detecting the events and states occurring in the programme-controlled unit. The programme-controlled unit described can be characterized by the fact that the ports of the crossbar comprise a diagnostic port, that the addresses, data and/or control signals which are transmitted between two other ports of the crossbar are additionally also supplied to the diagnostic port, and that the debug resources are connected to the diagnostic port of the crossbar.

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to Canadian Application Number______ filed Nov. 16, 2011, by the Canadian firm Gowling, Lafleur, Henderson LLP, under attorney docket number A8124182CA, which is hereby incorporated by reference. FIELD [0002] The present disclosure relates to a fluid storage tank assembly. BACKGROUND [0003] Fluid fracturing processes in oil and gas completion operations make use of large quantities of fluid typically stored in large fluid storage tanks located in close proximity to a wellbore. The tanks are typically assembled on a site on a temporary basis and then removed when use of the tank at the site is not longer required. Depending on the jurisdiction in which the tank is located, the size of the tank and the effective storage capacity of tank may be limited by local regulations, bylaws, licensing requirements, and other restrictions respecting the surface area covered by the tank, the permitted water levels in the tank for the protection of wildlife, the maximum load sizes that may be transported on public roads, and other factors. Some prior art storage tank designs are unable to provide adequate storage capacity while complying with such restrictions. [0004] Further, the fluid contained within the storage tank is typically maintained within specific temperature ranges suitable for the fracturing process through the use of heating systems. The cost of heating the fluid can be extremely high, especially in cold environments. Some prior art storage tank designs do not provide adequate insulation to effectively reduce heat loss from the tank, thus, resulting in significant heating costs. SUMMARY [0005] According to one aspect of the present disclosure, there is provided a fluid storage tank assembly comprising: a wall assembly circumscribing an interior chamber of the tank assembly and providing a thermal insulating layer, the wall assembly comprising two or more wall sub-assemblies removably stacked on top of each other, each wall sub-assembly comprising a plurality of removably interconnected wall panels circumscribing a portion of the interior chamber, the wall assembly configured to house a liner for containing a fluid; a floor assembly bounding a bottom portion of the interior chamber and providing a thermal insulating layer; and a roof assembly bounding a top portion of the interior chamber and providing a thermal insulating layer. [0009] The floor assembly may comprise a surface gradient operable to direct fluids contained in the tank assembly to a desired location on the floor assembly. The floor assembly may comprise a plurality of floor panels and an insulating layer fixed to the floor panels and shaped to provide the surface gradient. The plurality of floor panels may comprise an arrangement of parallel substantially rectangular panels configured to bound the bottom of the interior of the wall assembly, each panel extending across the interior of the wall assembly and having ends shaped to substantially conform with the interior boundary of the wall assembly. Alternatively, the plurality of floor panels may comprise an arrangement of substantially rectangular panels configured to bound the bottom of the interior of the wall assembly wherein panels located adjacent to the interior boundary of the wall assembly shaped to substantially conform with the interior boundary of the wall assembly. A portion of the floor panels near the desired location on the floor assembly may not comprise a thermal insulating layer. The insulating layer may comprise a channel therein configured to receive a suction pipe near the boundary of the interior of the wall assembly and direct the suction pipe to the desired location on the floor assembly. Each floor panel may be removably coupled to adjacent floor panels. The floor panels may comprise plywood and the insulating layer may comprise foam insulation. [0010] Each wall panel may further comprise an insulating layer fixed thereto. The insulating layer may comprise a spray foam applied to the exterior surface of each wall panel. Each wall panel may comprise a plurality of male connectors at one end and a plurality of female connectors at an opposite end, the male connectors configured to be received by and removably coupled to the female connectors of an adjacent wall panel in a wall sub-assembly, the female connectors configured to received by and removably coupled to the male connectors of an adjacent wall panel in the wall sub-assembly. The wall assembly may further comprise a plurality of joint pins and locking bars, each male connector may comprise one or more apertures configured to receive a joint pin therethrough, each female connector may comprise one or more apertures configured to receive a joint pin therethrough, each female connector further comprises a plurality of gussets extending from an exterior surface of the female connector and shouldering one of the apertures therein, each gussets comprising an aperture configured to receive a locking bar therethrough, the apertures of the male connectors and female connectors may be configured to be in alignment with one another to receive a joint pin therethrough when the male connectors are received by the female connectors, and each locking bar may be operable to be received by the apertures of the gussets of a female connector and interact with a joint pin received by a female connector and a male connector received by the female connector to resist the withdrawal of the joint pin therefrom. Each wall sub-assembly may be removably coupled to an adjacent stacked wall sub-assembly by a cooperating tongue and groove assembly. The wall panel of at least one of the removably coupled wall sub-assemblies may comprise a bottom stiffener fixed to the wall panel at its bottom edge and running parallel thereto, the bottom stiffener and the portion of wall panel near its bottom edge defining the tongue of the tongue and groove assembly, and the wall panel of at least the other of the removably coupled wall sub-assemblies may comprise a top stiffener fixed to the wall panel an offset distance below its top edge and running parallel thereto and a guide plate fixed to the top stiffener and extending vertically therefrom, the top stiffener, the guide plate and the portion of the wall panel within the offset distance defining the groove of the tongue and groove assembly. Each wall panel may further comprise a plurality of stiffeners coupled thereto for providing additional structural support to the wall panel. [0011] The roof assembly may further comprise a plurality of flexible roof segments and a fastening assembly, the fastening assembly operable to couple adjacent roof segments to one another. The roof assembly further may comprise a support pole assembly comprising one or more poles extending from the bottom of the tank assembly above the top of the wall assembly, the support pole assembly at least partially supporting the roof segments. The roof assembly may further comprise a drainage assembly comprising a plurality of apertures through the roof segments located at low points on the roof segment formed by a natural sag of the roof segments between the support pole assembly and the top of the wall assembly. Each roof segment may comprise a top portion and a skirt portion, the top portion configured to substantially cover the top of the wall assembly, and the skirt portion configured to extend down a portion of the exterior surface of the wall assembly. The skirt portion of each roof segment may be removably coupled to the wall assembly. The roof assembly may further comprise a lifting assembly fixed to the roof segments providing a point of attachment for positioning and orienting the roof segments. The lifting assembly may comprise one or more of Velcro straps and safety buckles. The roof segments may comprise vinyl with a water resistant coating. The drainage assembly may further comprise a mesh layer over each aperture in the roof segments. BRIEF DESCRIPTION OF THE DRAWINGS [0012] FIG. 1 provides a front perspective view of a modular fluid storage tank assembly according to one embodiment. [0013] FIG. 2 provides a front perspective view and detailed views of the wall assembly of the tank shown in FIG. 1 . [0014] FIGS. 3 and 4 provide front perspective views and detailed views of the upper wall sub-assembly of the wall assembly shown in FIG. 2 . [0015] FIGS. 5 and 6 provide front perspective views and detailed views of the lower wall sub-assembly of the wall assembly shown in FIG. 2 . [0016] FIG. 7 provides a side elevation view and front perspective view of a joint pin of the wall assembly shown in FIG. 2 . [0017] FIG. 8 provides a side elevation view and front perspective view of a locking bar of the wall assembly shown in FIG. 2 . [0018] FIG. 9 provides a front perspective view of the coupling of two adjacent wall panels as shown in FIGS. 3 and 4 with the joint pin shown in FIG. 7 and the locking bar shown in FIG. 8 . [0019] FIG. 10 provides a plan view and front elevation view of the floor assembly of the tank shown in FIG. 1 . [0020] FIGS. 11A to 11C provide a front perspective view and cross-sectional views of the roof assembly of the tank shown in FIG. 1 . [0021] FIG. 12 provides a flow diagram of a method of assembling the tank shown in FIG. 1A according to one embodiment. DETAILED DESCRIPTION [0022] The embodiments of the present disclosure relate to a modular fluid storage tank assembly and a method of assembling the same. The fluid storage tank assembly comprises a modular design that facilitates the efficient transportation and the rapid assembly and disassembly of the tank. Further, the fluid storage tank assembly is designed to reduce heat loss from fluids contained in the tank. [0023] Referring to FIGS. 1A and 1B , a fluid storage tank assembly 10 according to one embodiment is shown generally comprising a wall assembly 20 , a roof assembly 30 , a floor assembly 40 , and a liner 50 . [0024] Wall Assembly [0025] Referring to FIG. 2 , the wall assembly 20 generally comprises an upper wall sub-assembly 210 , a lower wall sub-assembly 250 , joint pins 300 , locking bars 320 , wall braces 340 , and clamp assemblies 360 . The components of the wall assembly 20 are generally manufactured from steel plate of suitable grade and thickness. Alternatively, the wall assembly 20 may be manufactured from any suitable material. Further, while the wall assembly 20 is depicted in the present embodiment as comprises upper and lower wall sub-assemblies, it sis to be understood that the wall assembly may comprises three or more wall sub-assemblies stacked on top of one another. [0026] The upper wall sub-assembly 210 generally comprises a plurality of interconnected upper wall panels 212 forming an upper hollow cylindrical enclosure. Similarly, the lower wall sub-assembly 250 generally comprises a plurality of interconnected lower wall panels 252 forming a lower hollow cylindrical enclosure. The upper wall sub-assembly 210 is positioned on top of and in axial alignment with the lower wall sub-assembly 250 forming an extended hollow cylindrical enclosure configured to retain the liner 50 within its interior. In the alternative, the wall assembly 20 may be configured to form other continuous circumferential enclosures, such as, for example, a hollow polygonal cylindrical enclosure. [0027] Referring to FIGS. 3 and 4 , each upper wall panel 212 generally comprises a wall plate 214 , stiffeners 215 , clamp mounts 222 , female connectors 225 , male connectors 236 , stacking components 237 , and an insulating layer 245 . [0028] The wall plate 214 comprises a curved rectangular plate having a curvature such that the assembly of a plurality of upper wall plates 214 forms a continuous hollow circular cylindrical enclosure. Alternatively, the wall plate 214 may comprise a planar rectangular plate or other form of plate such that the assembly of a plurality of upper wall plates 214 forms a continuous circumferential enclosures, such as, for example, a hollow polygonal cylindrical enclosure. [0029] Stiffeners 215 are fixed to the wall plate 214 to provide structural support, as well as, provide elements that can be used for the positioning and orientation of the wall panel 212 during assembly and disassembly of the tank 10 . The stiffeners 215 generally comprise a top stiffener 216 , vertical stiffeners 218 , a bottom stiffener 220 , and lifting lug stiffeners 224 . The top stiffener 216 comprises an elongate “L” shaped beam fixed to the wall plate 214 near its top edge and running parallel thereto from one end to the other end of the wall plate 214 . The vertical stiffeners 218 comprise elongate rectangular plates fixed at one or more locations along the length of the wall plate 214 and running from the bottom to the top of the wall plate 214 . The bottom stiffener 220 comprises elongate rectangular tube fixed to the wall plate 214 at its bottom edge and running parallel thereto from one end to the other end of the wall plate 214 . Lifting lug stiffeners 224 comprises rectangular plates fixed to the vertical stiffeners 218 and top stiffener 216 where an aperture is provided through the lifting lug stiffener 224 and the vertical stiffener 218 or top stiffener 216 . The apertures serve as attachment points for hooks or other devices for the positioning and orientation of the upper wall panel 212 during assembly and disassembly of the tank 10 . Alternatively, the stiffeners 215 may comprise more or less vertical, horizontal or other stiffeners for providing structural support, as well as, elements that can be used for the positioning and orientation of upper wall panels 212 during assembly and disassembly of the tank 10 . [0030] Female connectors 225 generally comprise a female backbone 226 , female inside plates 228 , female outside plates 230 , and locking bar gussets 234 , 236 . The female backbone 226 comprises a generally rectangular plate fixed to one longitudinal end of the wall plate 214 running from the bottom to the top of the wall plate 214 . The female backbone 226 has a thickness selected to permit the male connectors 236 to be received by the female connectors 225 . Alternatively, the wall plate 214 may serve as the female backbone 226 . The female inside plates 228 comprise generally rectangular plates that are fixed to the inner surface of the female backbone 226 spaced along the length of the female backbone 226 , and extend away from the wall plate 214 in a direction parallel to the length thereof Similarly, the female outside plates 230 comprise generally rectangular plates that are fixed to the outer surface of the female backbone 226 spaced along the length of the female backbone 226 , and extend away from the wall plate 214 in a direction parallel to the length thereof. Each female outside plate 230 is positioned on the outside surface of the female backbone 226 so as to oppose and pair with a corresponding female inside plate 228 fixed to the inside surface of the female backbone 226 . In addition, each female outside plate 230 and paired female inside plate 228 comprise a set of apertures 229 , 231 in alignment with one another that are configured to receive a joint pin 300 (as further described below). Each female connector 225 also comprises locking bar gussets 232 , 234 fixed to the outside surface of the female outside plate 230 shouldering one of the apertures 231 in vertical alignment with one another. The locking bar gussets 232 , 234 comprise apertures 241 that are aligned with apertures 241 in adjacent locking bar gussets 232 , 234 that are configured to receive a locking bar 320 . As further described below, the aperture 241 of locking bar gusset 234 comprises an open-ended aperture that extends to the top edge of the gusset 234 such that the handle 324 of the locking bar 320 can pass through the aperture 241 as the bar 322 of the locking bar 320 is inserted through the apertures 241 of the locking bar gussets 232 , 234 . For the purpose of this disclosure, each female inside plate 228 , corresponding female outside plate 230 , the portion of the female backbone 226 therebetween, and locking bar gussets 234 , 236 , will be referred to as a single female connector 225 . [0031] Male connectors 236 comprise generally rectangular plates that are fixed to the longitudinal end of the wall plate 214 opposite to the longitudinal end to which the female connectors 225 are fixed, and extending away from the wall plate 214 in a direction parallel to the length thereof Male connectors 236 are spaced along the length of the end of the wall plate 214 such that for each female connector 225 fixed to the opposite end of the wall plate 214 there is a corresponding male connector 236 in vertical alignment therewith. Each male connector 236 also comprises a set of apertures 237 configured to be in alignment with apertures 229 , 231 of a corresponding female connector 225 of an adjacent upper wall panel 212 when received thereby. In this manner, when the male connectors 236 of one upper wall panel 212 are received by the female connectors 225 of another upper wall panel 212 , the apertures 229 , 231 of each female connector 225 and the apertures 237 of each received male connector 236 will be in alignment such that they are capable of receiving a joint pin 300 therethrough. [0032] Stacking components 237 facilitate the stacking of upper wall panels 212 upon one another during transportation or storage. In addition, the stacking components 237 function to protect the insulating layer 245 of the upper wall panels 245 from damage that may be otherwise cause by adjacent stacked upper wall panels 212 . Stacking components 237 generally comprise stack up gussets 238 fixed near the longitudinal ends of the top stiffener 216 and extending in a generally perpendicular direction outwardly from the outer surface of the wall plate 214 , and stack up stand offs 240 fixed near the longitudinal ends of the bottom stiffener 220 and extending in a generally perpendicular direction outwardly from the outer surface of the wall plate 214 . In the alternative, other stacking components suitable for facilitating the stacking of upper wall panels 212 may be employed. [0033] Clamp mounts 222 comprise generally “I” shaped mounting brackets fixed to the outer surface of the wall plate 214 for mounting clamp assemblies 360 . As further described below, the clamp assemblies 360 are mounted to the clamp mounts 222 and clamped to the liner 50 to couple the liner 50 to the wall assembly 20 . Alternatively, other clamp mount 222 configurations suitable for mounting a clamp assembly 360 may be used. [0034] An insulating layer 245 is coupled to the outside surface of the wall plate 214 . The insulating layer 245 may be comprised of suitable spray foam applied to the outer surface of the wall plate 214 . Alternatively, the insulating layer 245 may be coupled to the inner surface of the wall plate 214 . In the further alternative, the insulating layer 245 may comprise insulating panels or other insulating materials coupled to the outer and/or inner surface of the wall plate 214 . [0035] Referring to FIGS. 5 and 6 , each lower wall panel 252 generally comprises a wall plate 254 , stiffeners 253 , guide plates 266 , female connectors 267 , male connectors 282 , and stacking components 283 . [0036] The wall plate 254 comprises a curved rectangular plate having a curvature such that the assembly of a plurality of lower wall plates 254 forms a continuous hollow circular cylindrical enclosure. Alternatively, the wall plate 254 may comprise a planar rectangular plate or other form of plate such that the assembly of a plurality of lower wall plates 254 forms a continuous circumferential enclosures, such as, for example, a hollow polygonal cylindrical enclosure. [0037] Stiffeners 267 are fixed to the wall plate 254 to provide structural support, as well as, provide elements that can be used for the positioning and orientation of the wall panel 252 during assembly and disassembly of the tank 10 . The stiffeners 267 generally comprise a top stiffener 256 , vertical stiffeners 258 , a bottom stiffener 260 , lifting lug stiffeners 262 , and lifting lug plates 264 . The top stiffener 256 comprises an elongate rectangular tube fixed to the wall plate 254 an offset distance below its top edge and running from one end to the other end of the wall plate 254 . The vertical stiffeners 258 comprise elongate rectangular plates fixed at one or more locations along the length of the wall plate 254 and running from the bottom to the top of the wall plate 254 . The bottom stiffener 260 comprises an elongate “L” shaped beam fixed to the wall plate 254 near its bottom edge and running parallel thereto from one end to the other end of the wall plate 214 . Lifting lug stiffeners 262 comprise rectangular plates fixed to the vertical stiffeners 258 where an aperture is provided through the lifting lug stiffener 224 and the vertical stiffener 218 . Lifting lug plates 264 comprise tabs fixed to and extending from the top stiffener 256 and having an aperture therethrough. The apertures in the lifting lug stiffeners 262 , vertical stiffeners 258 , and lifting lug plates 264 serve as attachment points for hooks or other devices for the positioning and orientation of the lower wall panel 252 during assembly and disassembly of the tank 10 . Alternatively, the stiffeners 267 may comprise more or less vertical, horizontal or other stiffeners for providing structural support, as well as, elements that can be used for the positioning and orientation of the lower wall panel 252 during assembly and disassembly of the tank 10 . [0038] Female connectors 267 generally comprise a female backbone 268 , female inside plates 270 , female outside plates 272 , horizontal guide plates 276 , and locking bar gussets 278 , 280 . The female backbone 268 comprises a generally rectangular plate fixed to one longitudinal end of the wall plate 254 running from the bottom to the top of the wall plate 254 . The female backbone 268 has a thickness selected to permit the male connectors 282 to be received by the female connectors 267 . Alternatively, the wall plate 254 may serve as the female backbone 268 . The female inside plates 270 comprise generally rectangular plates that are fixed to the inner surface of the female backbone 268 spaced along the length of the female backbone 268 , and extend away from the wall plate 254 in a direction parallel to the length thereof. Similarly, the female outside plates 272 comprise generally rectangular plates that are fixed to the outer surface of the female backbone 268 spaced along the length of the female backbone 268 , and extend away from the wall plate 254 in a direction parallel to the length thereof. Each female outside plate 272 is positioned on the outside surface of the female backbone 268 so as to oppose and pair with a corresponding female inside plate 270 fixed to the inside surface of the female backbone 268 . In addition, each female outside plate 272 and paired female inside plate 270 comprise a set of apertures 271 , 273 in alignment with one another that are configured to receive a joint pin 300 (as further described below). Each female connector 267 also comprises locking bar gussets 278 , 280 fixed to the outside surface of the female outside plate 272 shouldering one of the apertures 273 in vertical alignment with one another. The locking bar gussets 278 , 280 comprise apertures 287 that are aligned with apertures 287 in adjacent locking bar gussets 278 , 280 that are configured to receive a locking bar 320 . As further described below, the aperture 287 of locking bar gusset 280 comprises an open-ended aperture that extends to the top edge of the gusset 280 such that the handle 324 of the locking bar 320 can pass through the aperture 287 as the bar 322 of the locking bar 320 is inserted through the apertures 287 of the locking bar gussets 278 , 280 . Further, the top and bottom female connectors 267 also comprise horizontal guide plates 276 fixed to and spanning the bottom of the female inside plate 270 and female outside plate 272 of each top and bottom female connector 267 . The horizontal guide plates 276 function to align and guide the male connectors 282 of the wall panel 252 being received by the female connectors 267 . For the purpose of this disclosure, each female inside plate 270 , corresponding female outside plate 272 , the portion of the female backbone 268 therebetween, the locking bar gussets 278 , 280 , and the horizontal guide plates 276 (as applicable to the top and bottom female connectors 267 ), will be referred to as a single female connector 267 . [0039] Male connectors 282 comprise generally rectangular plates that are fixed to the longitudinal end of the wall plate 254 opposite to the longitudinal end to which the female connectors 267 are fixed, and extending away from the wall plate 254 in a direction parallel to the length thereof. Male connectors 282 are spaced along the length of the end of the wall plate 254 such that for each female connector 267 fixed to the opposite end of the wall plate 254 there is a corresponding male connector 282 in vertical alignment therewith. Each male connector 282 also comprises a set of apertures 283 configured to be in alignment with apertures 271 , 273 of a corresponding female connector 267 of an adjacent upper wall panel 252 when received thereby. In this manner, when the male connectors 282 of one lower wall panel 252 are received by the female connectors 267 of another lower wall panel 252 , the apertures 271 , 273 of each female connector 267 and the apertures 283 of each received male connector 282 will be in alignment such that they are capable of receiving a joint pin 300 therethrough. [0040] Guide plates 266 comprise tabs fixed to and extending from the top stiffener 256 spaced along the length of the top stiffener 256 . The guide plates 266 , top stiffener 256 and portion of the wall plate 254 extending above the top stiffener 256 , define a seat configured to receive and support the base of an upper wall panel 212 therebetween. In this manner, the bottom of the upper wall sub-assembly 210 is coupled to the top of the lower wall sub-assembly 250 through a tongue and groove assembly. In the alternative, the upper wall sub-assembly 210 may be coupled to the lower wall sub-assembly 250 using other suitable coupling mechanisms. [0041] Stacking components 283 facilitate the stacking of lower wall panels 252 upon one another during transportation or storage. In addition, the stacking components 283 function to protect the insulating layer 295 of the lower wall panels 252 from damage that may be otherwise cause by adjacent stacked upper wall panels 252 . Stacking components 283 generally comprise stack up gussets 284 fixed near the longitudinal ends of the bottom stiffener 260 and extending in a generally perpendicular direction outwardly from the outer surface of the wall plate 254 , and stack up stand offs 286 fixed near the longitudinal ends of the top stiffener 256 and extending in a generally perpendicular direction outwardly from the outer surface of the wall plate 254 . In the alternative, other stacking components suitable for facilitating the stacking of lower wall panels 252 may be employed. [0042] An insulating layer 295 is coupled to the outside surface of the wall plate 254 . The insulating layer 295 may be comprised of suitable spray foam applied to the outer surface of the wall plate 254 . Alternatively, the insulating layer 295 may be coupled to the inner surface of the wall plate 254 . In the further alternative, the insulating layer 295 may comprise insulating panels or other insulating materials coupled to the outer and/or inner surface of the wall plate 254 . [0043] Referring to FIG. 7 , joint pins 300 generally comprise a pin prong 302 and pin handle 314 . The pin prong 302 comprises spaced fingers 306 extending from a base 304 . The base 304 comprises a top surface 308 spanning between adjacent fingers 306 and a bottom surface 310 opposite the top surface 308 . The fingers 306 are sized to be received by and extend through (a) apertures 229 , 231 of a female connector 225 and apertures 237 of a male connector 236 of upper wall panel 212 when received by the female connector 225 , and (b) apertures 271 , 273 of a female connector 267 and apertures 283 of a male connector 282 of lower wall panel 252 when received by the female connector 267 . In addition, the fingers 306 comprise bevelled tips to assist in positioning the fingers 306 into apertures 229 , 231 , 236 and 271 , 273 , 283 . The pin handle 314 is a generally “U” shaped handle fixed to the bottom surface 310 of the base 304 of the pin prong 302 defining a void 316 between the pin handle 314 and bottom surface 310 . Alternatively, the joint pin 300 may comprise any number of fingers 306 . [0044] Referring to FIG. 8 , locking bars 320 generally comprise a bar 322 and a handle 324 . The bar 322 comprises a cylindrical rod sized to be received by and extend through (a) apertures 241 of locking bar gussets 232 , 234 of a female connector 225 of upper wall panel 212 and (b) apertures 287 of locking bar gussets 278 , 280 of a female connector 267 of lower wall panel 252 . The handle 324 comprises a cylindrical rod fixed to the bar 322 and extending in a generally perpendicular direction therefrom. The handle 324 has a thickness sized to fit between adjacent locking bar gussets 232 , 234 and 278 , 280 . [0045] Referring to FIG. 9 , during the assembly of the upper wall sub-assembly 210 and lower wall sub-assembly 250 , adjacent wall panels 212 , 252 are interconnected by inserting the male connectors 236 , 282 into the female connectors 225 , 267 such that the apertures 229 , 231 , 236 and 271 , 273 , 283 are in alignment. The fingers 306 of a joint pin 300 are then inserted through the apertures 229 , 231 , 236 and 271 , 273 , 283 , until the top surface 308 of the base 304 of the joint pin 300 contacts the outer surface of the female outside plate 230 , 272 of the female connector 225 , 267 . The bar 322 of the locking bar 320 is inserted into and slid through the apertures 241 , 287 of locking bar gussets 232 , 234 and 278 , 280 and through the void 310 between the bottom surface 310 of the base 304 of the pin prong 302 of the joint pin 300 and the handle 314 of the joint pin 300 . In the same motion, the handle 324 of the locking bar 320 is positioned to extend upwards such that it can be slid through the aperture 241 , 287 of locking bar gusset 234 , 280 . Once the handle 324 of the locking bar 320 has been slid through the aperture 241 , 287 of locking bar gusset 234 , 280 , the handle 324 is rotated so that it extends downwards and rests between the locking bar gusset 234 , 280 and adjacent locking bar gusset 232 , 278 . In this manner, the locking bar 320 prevents the joint pin 300 from being withdrawn from the male connector 236 , 282 and female connector 225 , 267 , and the locking bar 320 is prevented from further translational motion without first rotating the handle 324 of the locking bar 320 so that it extends upwards and can translate through the locking bar gusset 234 , 280 . This mechanism of interconnecting adjacent wall panels 212 , 252 of the upper wall sub-assembly 210 and lower wall sub-assembly 250 provides a strong and secure coupling between adjacent wall panels, 212 , 252 capable of resisting the high forces typically exerted by fluids contained in the tank 10 . [0046] Referring again to FIG. 2 , wall braces 340 generally comprise supporting plates configured to extended between and couple to the vertical stiffeners 218 , 258 of vertically adjacent wall panels 212 , 252 in the assembled tank 10 . The wall braces 340 function to restrict relative motion between vertically adjacent wall panels 212 , 252 in the assembled tank 10 . Alternatively, other forms of wall braces 340 that are suitable to restrict relative motion between vertically adjacent wall panels 212 , 252 in the assembled tank 10 can be utilized. [0047] Clamp assembly 360 generally comprises a clamp bar 362 , clamp 364 and anti-vibration mount 366 . The clamp bar 362 comprises a tube to which the clamp 364 is fixed to the outer surface and the anti-vibration mounts 366 are fixed to the inner surface. The clamp 364 is configured to clamped to the liner 50 to couple the liner 50 to the wall assembly 20 . The clamp assembly 360 is configured to mount to the clamp mount 222 of upper wall panel 212 . [0048] Floor Assembly [0049] Referring to FIG. 10 , the floor assembly 40 functions to insulate fluids contained in the tank 10 from the ground and direct the fluids to the location within the tank 10 where a suction pipe is located for withdrawing the fluid from the tank. The floor assembly 40 generally comprises a plurality of modular floor panels 402 and an insulating layer 404 . The floor panels 402 are configured to substantially cover the entire surface area of the ground captured within the interior circumferential boundary of the lower wall sub-assembly 250 . The panels 402 are manufactured from overlapping plywood sheets that are glued and screwed together. The plywood sheets are cut into elongate generally rectangular strips that are configured to extend across a strip of the ground within the interior of the lower wall sub-assembly 250 . The floor panel(s) 402 crossing the centre of the ground within the interior of the lower wall sub-assembly 250 will have the longest length, spanning the diameter of the interior of the lower wall sub-assembly 250 , followed by successively shorter length floor panels 402 the further a floor panel 402 is located from the centre of the interior of the lower wall sub-assembly 250 . The ends of the floor panels 402 are shaped to substantially conform to the shape of the interior circumferential boundary of the lower wall sub-assembly 250 . Alternatively, the panels 402 may comprise a plurality of rectangular panels for positioning within the interior portion of the floor assembly 30 and plurality of shaped panels configured to generally conform to the shape of the interior circumferential boundary of the assembled lower wall sub-assembly 250 for positioning adjacent to the boundary. In the further alternative, the floor panels 402 may be manufactured from fibreglass, composite fibreglass or any other suitable material. In he further alternative the floor panels 402 may be coupled to one another by Velcro or any other suitable attachment mechanism. [0050] An insulating layer 404 is fixed to the top of the floor panels 402 . The insulating layer 404 comprises a plurality of insulating foam panels that are positioned on top of the floor panels 402 such that the elevation of the insulation at the boundary of the interior of the lower wall sub-assembly 250 is higher than the elevation of the insulation at the centre of the interior of the lower wall sub-assembly 250 . In this manner, the gradient of the floor assembly 40 will tend to drain fluid within the liner 50 contained by the tank 10 towards the centre of the interior of the lower wall sub-assembly 250 where a suction pipe for withdrawing the fluid from the tank 10 will be located. Further, the gradient of the floor assembly 40 permits the tank 10 to be assembled on surfaces that are not level since fluid the gradient of the floor assembly 40 will compensate for imperfections in the level of the surface and direct the fluid to the location of the suction pipe. Alternatively, where it is desired to locate the suction pipe at another location within the interior of the lower wall sub-assembly 250 , the insulating layer 404 can be configured on top of the floor panels 402 such that the gradient of the floor assembly 400 directs the fluid contained in the tank 10 to be directed to that location. [0051] An insulating layer 404 may be fixed to every floor panel 402 or only to a subset of floor panels 402 as is required to provide a desired gradient of the floor assembly 40 . For example, in some embodiments, the floor panels 402 in closest proximity to the intended location of the suction pipe have an insulating layer 404 fixed to the floor panels 402 in order to provide an area of minimum elevation that the fluid in the tank 10 will be directed to by the gradient of the floor assembly 40 . In addition, a channel may be cut into the insulating layer 404 to receive the suction pipe near the boundary of the interior of the lower wall sub-assembly 250 and direct the suction pipe to a desired location within the interior of the lower wall sub-assembly 250 . Alternatively, the insulating layer 404 may be manufactured from other suitable insulating materials. [0052] Roof Assembly [0053] Referring to FIGS. 11A to 11C , the roof assembly 30 functions to cover the top of the tank 10 and thereby prevent wildlife from entering the tank 10 and trap heat within the tank 10 . The roof assembly 30 generally comprises roof segments 502 , a fastening assembly 508 , a lifting assembly 512 , a drainage assembly 514 , and a support pole assembly 516 . [0054] Roof segments 502 comprise two roof halves 502 A, 502 B each comprising a top portion 504 A, 504 B and a skirt 506 A, 506 B. Alternatively, the roof segments 502 may comprise more than two segments. When assembled, the top portion 504 of the roof segments 502 covers the top of the upper wall sub-assembly 200 and the skirt 506 extends down a portion of the exterior surface of the upper wall sub-assembly 200 . Optionally, the skirt 506 of the roof assembly 30 may be coupled to the wall assembly 20 by way of a tether or other suitable coupling. [0055] The roof segments 502 are manufactured from a flexible insulating material, such as, for example, vinyl treated with a water proof coating, nylon, plastics or any other suitable material. Alternatively, the roof segments 502 can be manufactured from other suitable materials that can prevent wildlife from entering the tank 10 and trap heat within the tank 10 . [0056] The roof segments 502 are divided into two halves in order to facilitate the transportation and assembly of the roof assembly 30 . The roof segments 502 are coupled to one another along their interior edges 508 by way of the fastening assembly 510 . The fastening assembly 510 comprises Velcro straps and safety buckles that are fixed to the roof segments 502 about the length of their interior edges 508 . Alternatively, the fastening assembly 510 may comprise other suitable fastening components capable of fastening the roof segments 502 to one another. [0057] The lifting assembly 512 comprises lifting loops fixed to the top portion 504 of the roof segments 502 about the length of the interior edge 508 of the roof segments 502 . The lifting assembly 512 provides a point of attachment that can be coupled to by a hook or other suitable device to position of the roof segments 502 on top of the upper wall sub-assembly 200 and in relative position to one another to facilitate the fastening of the fastening assembly 510 . In the alternative, the lifting assembly 512 may comprise other suitable lifting components. [0058] The support pole assembly 516 comprises a pole mounted on top of the liner 50 about the centre of the floor assembly 40 and extending vertically therefrom above the top of the wall assembly 20 . The support pole assembly 516 functions to support a portion of the weight of the roof assembly 30 and to direct rain water, snow and other fluids forming on top of the roof assembly 30 to the drainage assembly 514 . The support pole assembly 516 may optionally comprise a base positioned on top of the liner 50 and configured to receive the bottom of the pole. The base may comprise a water tank or other suitable base structure. Alternatively, the support pole assembly 516 may comprises a plurality of poles mounted at desired locations about interior of the tank 10 . [0059] The drainage assembly 514 functions to drain rain water, snow and other fluids forming on top of the roof assembly 30 into the tank 10 . The drainage assembly 514 comprises a plurality of drain apertures through the roof segments 502 located at low points on the roof segments 502 that form due to the natural sag of the roof segments 502 between the support pole assembly 516 and the top of the wall assembly 20 . The drainage assembly 514 also comprises a mesh layer over each aperture to prevent wildlife from entering the tank 10 therethrough. [0060] Liner [0061] Referring to FIGS. 1A and 1B , the liner 50 comprises a flexible polyurethane container housed within the interior of the wall assembly 20 and draped over the sides of the wall assembly 20 and coupled thereto by clamp assemblies 360 . The liner 50 functions to provide a water proof container for receiving fluid within the tank 10 . [0062] Assembly Process [0063] Referring to FIG. 12 , one embodiment of a method 600 of assembling the tank 10 is provided. In block 602 , the components of the tank 10 are transported to a site where the tank 10 is to be assembled, typically by one or more semi-trailer trucks. In block 604 , the components of the tank 10 are offloaded to desired location on the site, typically by a picker truck. [0064] In block 606 , a first lower wall panel 252 is located to a desired position and orientation, typically by a picker truck. The first lower wall panel 252 is supported in an upright position by a temporary support assembly, typically comprising removable support beams. In block 608 , the next lower wall panel 252 is positioned and oriented next to the first lower wall panel 252 such that the male connectors 282 of either the first lower wall panel 252 or next lower wall panel 252 is received by the female connectors 267 of the other of the first lower wall panel 252 or next lower wall panel 252 in alignment therewith. In block 610 , the joint pin 300 is inserted through the aligned female connectors 267 and male connectors 282 , and locking bar 400 is inserted to secure the joint pin 300 , in the manner described above. In block 612 , if the lower wall sub-assembly 250 is completed, the method 600 proceeds to block 614 , otherwise, blocks 608 to 612 are repeated for the next lower wall panel 252 . [0065] In block 614 , a first upper wall panel 212 is located to a desired position and orientation on top of the lower wall sub-assembly 250 , typically by a picker truck. As described above, the bottom of the first upper wall panel 212 is received by the seat defined by the guide plates 266 , top stiffener 256 and portion of the wall plate 254 extending above the top stiffener 256 of the lower wall panel 252 for which the first upper wall panel 212 is positioned on top of. The first upper wall panel 212 is positioned with respect to its supporting lower wall panel 252 such that the vertical stiffeners 218 , 258 of the first upper wall panel 212 and supporting lower wall panel 252 are in horizontal alignment. The first lower wall panel 212 is supported in an upright position by a temporary support assembly, typically comprising removable support beams. In block 616 , the next upper wall panel 212 is positioned and oriented next to the first upper wall panel 212 such that the male connectors 236 of either the first upper wall panel 212 or next upper wall panel 212 is received by the female connectors 225 of the other of the first lower wall panel 212 or next lower wall panel 212 in alignment therewith. In addition, similar to the first upper wall panel 212 , the next upper wall panel 212 is positioned in the seat provide by a supporting lower wall panel 252 . Similar to the first upper wall panel 212 , the next upper wall panel 212 is positioned with respect to its supporting lower wall panel 252 such that the vertical stiffeners 218 , 258 of the next upper wall panel 212 and supporting lower wall panel 252 are in horizontal alignment. [0066] In block 618 , the joint pin 300 is inserted through the aligned female connectors 225 and male connectors 236 , and locking bar 400 is inserted to secure the joint pin 300 , in the manner described above. In block 620 , if the upper wall sub-assembly 210 is completed, the method 600 proceeds to block 622 , otherwise, blocks 616 to 620 are repeated for the next upper wall panel 212 . [0067] In block 622 , the wall braces 340 are attached to selected vertical stiffeners 218 , 258 of aligned lower wall panel 252 and upper wall panels 212 . In block 624 , clamp assemblies 260 are coupled to clamp mounts 222 of upper wall panels 212 . [0068] In block 626 , the floor panels 402 are set out on the ground within the interior circumferential boundary of the lower wall sub-assembly 250 in their designated locations. In block 628 , the insulating layer 404 is fixed to the top of the floor panels 402 such that the elevation of the insulation at the boundary of the interior of the lower wall sub-assembly 250 is higher than the elevation of the insulation at the centre of the interior of the lower wall sub-assembly 250 . [0069] In block 630 , the liner is positioned inside of the wall assembly 20 , draped over the upper edges of the wall assembly 20 and coupled to clamp assemblies 260 . In block 632 , the suction pipe for withdrawing fluid from the tank 10 and the inlet and outlet pipes used for heating fluid contained in the tank 10 are inserted into the interior of the liner 50 within the wall assembly 20 . [0070] In block 634 , the support pole assembly 516 is mounted on top of the liner 50 about the centre of the floor assembly 40 and extending vertically therefrom above the top of the wall assembly 20 . In block 636 , the roof segments 502 are laid out on the ground and are coupled together by the fastening assembly 508 . In block 638 , the assembled roof segments 502 are positioned on top of the wall assembly 20 and support pole assembly 516 such that the skirt 506 of the roof assembly 30 extends down a portion of the exterior of the wall assembly 20 , typically through the use of a picker truck. In 40 , optionally, the skirt 506 may be coupled to the wall assembly 20 by way of tethers or other suitable coupling devices. [0071] After the completion of method 600 , the tank may be filled with fluid and used in operation. [0072] While particular embodiments of the present invention has been described in the foregoing, it is to be understood that other embodiments are possible within the scope of the invention and are intended to be included herein. It will be clear to any person skilled in the art that modifications of and adjustments to this invention, not shown, are possible without departing from the spirit of the invention as demonstrated through the exemplary embodiment. The invention is therefore to be considered limited solely by the scope of the appended claims.

A fluid storage tank assembly comprising a wall assembly, a floor assembly and a roof assembly. The wall assembly providing a thermal insulating layer comprising two or more wall sub-assemblies removably stacked on top of each other that circumscribe an interior chamber of the tank assembly. Each wall sub-assembly comprises a plurality of removably interconnected wall panels circumscribing a portion of the interior chamber. The wall assembly is configured to house a liner for containing a fluid. The floor assembly bounds a bottom portion of the interior chamber and provides a thermal insulating layer. The roof assembly bounds a top portion of the interior chamber and provides a thermal insulating layer.

CROSS-REFERENCE TO RELATED APPLICATIONS This Application is a continuation of and claims priority from U.S. patent application Ser. No. 14/713,097, entitled, “Systems And Methods For Online Direct Marketing And Advertising On Registration Based Websites And Web-Based Email Systems”, filed May 15, 2015, which in turn claims priority to U.S. patent application Ser. No. 11/581,980, entitled “Systems and methods for online marketing and advertising on email systems” filed Oct. 17, 2006, which in turn claims priority to U.S. patent application Ser. No. 10/667,103, entitled “Email method and system” filed on Sep. 17, 2003, U.S. Provisional Application Ser. No. 60/411,835, entitled “Systems and Methods for Online Direct Marketing on Web-Based Email Systems and Websites Over a Network,” filed on Sep. 18, 2002, U.S. Provisional Application Ser. No. 60/422,293, entitled “Systems and Methods for Online Direct Marketing and Advertising on Email Systems Over a Network,” filed on Oct. 30, 2002, U.S. Provisional Application Ser. No. 60/457,407, entitled “Systems and Methods for Online Marketing and Advertising on Email Systems Over a Network,” filed on Mar. 25, 2003, U.S. Provisional Application Ser. No. 60/478,212, entitled “Systems and Methods for the Enhancement of Email Client User Interfaces and Email Message Formats,” filed on Jun. 12, 2003, and U.S. Provisional Application Ser. No. 60/480,076, entitled “Systems and Methods for Online Direct Marketing and Advertising on Registration Based Websites and Web-Based Email Systems,” filed on Jun. 20, 2003, each of which is incorporated by reference herein in its entirety. FIELD OF THE INVENTION An online direct marketing and advertising system is presented in which advertisers have an opportunity to send targeted promotions, coupons and offers that are placed in a user's web-based email account without the drawbacks of sending conventional email. The advertiser transmits promotion content and targeting information to the system wherein the promotions will be placed in a separate folder or a special “offer box” within user's web-based mail account. The promotions do not take up disk quota space and, at the same time, the system does not need to divulge private user information to the advertiser. This invention also includes a dynamic graphical previewing system to allow recipients to easily preview promotional offers. This system provides a means to free web-based email providers from the need to obtain opt-in permission to send offers to their users as providers are frequently prohibited from sharing the user's email address and personal information with merchants. Also this system helps aggregate promotions for smaller web-based email providers and ISPs who are not big enough individually to attract large promoters to send direct marketing offers to their system. This system can either reside within a web-based email provider's system or be delivered over a network to multiple web-based email providers. The invention also applies to sending offers to consumers through other kinds of registration based web sites as well, such as portals. BACKGROUND OF THE INVENTION Direct mail and coupons is a huge business. It is not only effective but also receivers of these promotions find value in it. It allows merchants a chance to reach new customers and consumer-packaged goods manufacturers to introduce or promote products to a wide audience. The receivers have a chance to save money and an incentive to try out new products. The Internet looks poised to bring a whole new level of effectiveness and personalization to direct mail and coupons. Until now the methods introduced on the Internet include direct offers via email and coupon portals. Unfortunately both these methods have proven ineffective. Email has proven to be an inadequate medium for online promotions because of its inherent “free” nature. In the offline world of postal direct mail, it costs promoters to send offers to households. The promoter has to pay for printing and mailing costs which would range anywhere from 40 cents to a few dollars for each household mailed, therefore, even if the promoter could obtain the address of every household in the US it would not be cost effective to send them to every single household. But, because sending emails is free, promoters have no barrier to send an email to every email address they can get their hands on—leading to the practice of sending massive amounts of untargeted unsolicited email—Spam. Not every promoter participates in spamming, but because of the rampant practice of Spam, users have become numb to offers received through email—whether they be targeted or not—thus crippling a potentially effective channel for direct marketing and promotions. Coupon portals such as MyCoupons.com, Valpak.com and Coolsavings.com have been set up to serve coupons of merchants and consumer goods manufacturers to Internet users. Unfortunately, most users do not actively search for coupons and offers; they merely take up the offer when it is presented to them, either through coupons received in the mail or in the Sunday newspapers. The majority of the users who frequent coupon portals are “coupon fans” and penny pinchers, not necessarily the kind of demographic the promoters are looking for. Web-based email providers like Hotmail and Yahoo have also set up their own direct-email services where users opt-in to receive offers from merchants who sign up with the providers to send targeted offers to users of these web-based email providers. One such service is Hotmail's MSN Featured Offers. The drawback is that recipients need to opt-in to receive these promotions and the promotions still clutter the user's inbox and they do not expire. One of the further drawback is that these promotions suffer the drawback of email, where the user is forced to open the promotion to see its contents as the subject line of the promotion such as “HP Printer 5500C for $100” often does not provide enough information for the user (What is the HP 5500C? What does it look like?). One method used by promotions provider Greenmail.com is where promotional graphics are shown instead of text in the listing of promotional offers. This method suffers from a cluttering of the screen as static graphics take up a large portion of the browser screen space as opposed to text (Greenmail.com is not an email site). Aside from the major web-based email providers like Hotmail and Yahoo, there are many smaller Internet Service Providers (ISP) who provide web-based email service to their customers. Since these ISPs are focused mainly on the operations of their network, they do not have the resources to set up their own direct marketing organization and would benefit from being part of an affiliate system that would supply the technology and direct marketing content to them. SUMMARY OF THE INVENTION It is an object of the present invention to provide online marketing and advertising systems and associated methods to deliver targeted promotions to web-based email users, email users and other registration based web-site visitors that are associated with predetermined marketing profiles. These profiles allow the web-based email providers to allow marketers to target the recipients while preserving the personal information of each recipient and protecting their users from potential spam. Here on after, the document will mainly refer to web-based email systems and providers—however the invention may apply equally to all other kinds of registration based websites. The present invention may be hosted on a web-based email provider's system or be hosted by a 3rd party and the promotions be delivered over a network to multiple web-based email systems. It is a further object of the present invention to provide marketing systems and associated methods to deliver targeted promotions to web-based email users within the web-based interface but without taking up the user's email disk quota space, with the ability to manage these promotions from a server separate from the server that manages the user's email content. It is still a further object of the present invention to provide marketing systems and associated methods to deliver promotions to web-based email users in a specialized folder within the web-based email interface or in a special promotion only section (Offer Box) within the inbox of the web-based email interface. The promotions may have expiry dates, when the promotion will be automatically deleted from the system. It is still a further object of the present invention where special search related offers are placed in the above mentioned folders or Offer Box, wherein the offers are based on the user's prior web search queries. It is still a further object of the present invention to provide marketing systems and associated methods to allow a method to preview a promotion directly from an aggregate listing of promotions, or a mixed listing of promotions and email without opening the message itself, allowing the promoter to put creative mechanisms such as graphics, animation or multi-media in the preview to entice the user to open the promotion itself. The preview routine further helps the user by giving the user a better idea of the content of the promotion than by guessing from the subject line of the promotion. It is still a further object of the present invention to provide marketing systems and associated methods to users of the web-based email service to select promotions and coupons online and send them to be printed by a separate system and mailed through the postal service to the user to be redeemed at a store. The systems and method of the present invention therefore enables promotion recipients who do not have access to a printer to take advantage of these promotions as well as provide coupon issuers who do not want their coupons to be duplicated a means to participate in online promotional methods. In a preferred embodiment, web-based email providers collect information about users and this information is categorized and created into profiles. These profiles and not the actual customer information is transferred to a central system that provides the promotions for a network of web-based email providers. In a preferred embodiment the invention is realized over a networked computer environment, where in promoters create promotions and specify the target profiles of their intended recipients, wherein the system will automatically place the promotions into specialized promotion folders in the web-based email providers' users' accounts. Users who log into their account will be able to click to the promotion folder(s) and preview or purview the promotions. In a preferred embodiment, the listings of the promotions will each include a triggering routine that will trigger the showing of a preview—either an image or graphic, an HTML layer overlay or a Macromedia Flash overlay graphic or any other routines obvious to those skilled in the art. The triggering routine in the preferred embodiment will be an icon. In a preferred embodiment, the invention is realized over a networked computer environment, wherein a promotions server resides as a node on the network. The various promotions are stored on the network of the server and preferably on the server. When, for example, a user using a browser accesses the web page that is affiliated with the promotions server process, which contains the listings of the promotions, the affiliated page's encoding includes content served by the promotions server process. The affiliate web-based email provider's web server would also contain a client process that will send encoded profile information to the promotions server to enable the server to serve the correct promotions to the user. The user will be able to view a listing of promotions when logged in to his web-based email account. Upon moving the mouse on an offer listing or a triggering icon, a JavaScript or VBscript code is executed on his browser that will make a small overlay window appear showing a preview of the content of the promotion. Upon clicking on a link on the listing, the browser will then send a request to the affiliate web-server process, which in turn forwards the request to the promotions server to load the content of the promotion. In a preferred embodiment, the previews of the promotions will be loaded only after the visible content of the listings are loaded to enable the page to look as if it has completed loading earlier. The previews of the promotion, which may contain graphics and other audio or visual elements, will load in the background while the user is viewing the listing. This can be achieved using script code such as JavaScript that is loaded into the user's browser, server code, or a combination of both. In a preferred embodiment, the invention includes a central printing server that is connected to the promotions server over a network. The central printing server will print out promotions and coupons that will be mailed to users of affiliated web-based email providers. According to an embodiment of the present invention, a method for placing preview enhanced messages in registration based websites comprises: a user node having a browser program coupled to a network, the user node providing requests for information on the network; a promotions server node in operative association with a data repository responsive to a request and deliver promotions to the user node. According to an embodiment of the present invention, the promotions server node contains profile information about the user and is able to send targeted promotions to the user. According to an embodiment of the present invention, the promotion listing contains a mechanism to dynamically display and hide graphical elements that serve as a teaser to the promotions on top of the aggregate listing of promotions. According to an embodiment of the present invention, the mechanism is an icon. According to an embodiment of the present invention, the promotion listing is in a separate folder than the listing of the user's email (ie. inbox). According to an embodiment of the present invention, the promotion listing is in the same page as the listing of the user's email (ie. inbox). According to an embodiment of the present invention, a method for placing search query based offers in the main page of registration based websites comprises: a site to which promotions may be displayed to users visiting the site; a search database with keywords keyed to certain sites an mechanism to allow the user to enter a search query; a persistence datastore to hold and remember the user's search query; a mechanism to display a plurality of results of the search query to the user at another point in time. According to an embodiment of the present invention, the search database contains paid listing in which results will allow the reader to be sent to the promoter's web-page or promotion content. According to an embodiment of the present invention, the registration based website is a web-based email provider and the results appear within the page displaying the user's email listing. According to an embodiment of the present invention, the search result listing contains a mechanism to dynamically display and hide graphical elements that serve as a teaser to the promotions on top of the aggregate listing of search results. According to an embodiment of the present invention, the mechanism is an icon. According to an embodiment of the present invention, the search result listing contains a mechanism to dynamically display and hide graphical elements that serve as a teaser to the promotions on top of the aggregate listing of search results. According to an embodiment of the present invention, the mechanism is an icon. According to an embodiment of the present invention, a system of delivering promotions to web-based email users comprises: a server running a web-based email system; a data repository at the web-based email provider maintaining a database of user demographics information; a process running on the web-based email provider's system interacting with; a promotions server on the network containing; a data repository containing promotions targeted towards one or more selections of demographics stored in the data repository at the web-based email provider. According to an embodiment of the present invention, the promotions are displayed in a separate page than the web-based email provider's emails. The promotions are displayed in a virtual folder that is separate from the user's emails. According to an embodiment of the present invention, the promotions are stored separately from the user's email and does not take up space in the user's disk quota. According to an embodiment of the present invention, the promotions are sent as email to the user's account. According to an embodiment of the present invention, the listing of the promotions approximate the look of email listing with attributes including name of promoter or from, offer or subject, date, expiry, distance from the user's geographic location and category or type of promotion. According to an embodiment of the present invention, the listing of the promotions are sortable according to the attributes such as name, date, expiry date and distance. According to an embodiment of the present invention, the system allows the promoters the ability to perform splits on promotions—the ability to simultaneously send different promotions or different versions of the same promotion, to a specific population of users and having the users receive no more than one copy or version of the the promotion. The system will provide promoters the ability to compare the effectiveness of the different promotions to each other. According to an embodiment of the present invention, the system further comprises a software module to allow the recipient to rate the promotion in terms of interest, value or preference and an associated data storage to store the rating information. According to an embodiment of the present invention, the system further comprises a software module to enable the recipient of the promotion to save, sort and categorize offers by a predetermined classification, and to request the promotion to be printed and mailed to his address. According to an embodiment of the present invention, promotions are automatically deleted from the promotion folder when the expiry date of the promotion is reached. According to an embodiment of the present invention, the system further comprises a software module to allow promotions to be searched by the text content of the promotions, name of promoter, category and geographic location of the store. According to an embodiment of the present invention, a method for displaying a preview of a message on a web page which consists of: message content stored in a data repository; a listing of a plurality of messages on a web-page; preview content for the plurality of messages that can be visually visible overlaying a portion of the visible portion of a web-page; a triggering mechanism which will trigger the appearance of the preview content; According to an embodiment of the present invention, the message listing comprises promotions shown in a web-based email provider's user interface According to an embodiment of the present invention, the message listing comprises emails shown in a web-based email provider's user interface. According to an embodiment of the present invention, the preview is a hidden HTML layer containing graphics, HTML content, audio, Macromedia Flash content or Java applet According to an embodiment of the present invention, the triggering mechanism consists of an image icon and associated script on the web-browser that will trigger the appearance of the preview content when the user hovers the mouse over it. According to an embodiment of the present invention, the triggering mechanism is a script executing on a web-browser that detects the mouse positioned over certain elements of a particular list element and triggering the appearance of the preview content for the the element. According to an embodiment of the present invention, the method further comprises a mechanism used to delay the load of the hidden preview content until the visible preview contents are loaded. According to an embodiment of the present invention, the method further comprises a mechanism used to delay the load of the hidden preview content until the user activates the trigger for the preview. According to an embodiment of the present invention, the visible preview will be deactivated or become hidden when the user moves the mouse of the triggering element, or after a predetermined time has elapsed. According to an embodiment of the present invention, the loading of the preview content uses a predictive algorithm to determine the order in which the content should be loaded. The algorithm may take into account, the priority given to the promotion, the size of the preview content, real-time triggering order of the previews by the user which may include the proximity of the non-yet-loaded previews from previously viewed and loaded previews. According to an embodiment of the present invention, a preview content that is triggered is not made visible until the specific preview content being triggered has completed loading. While the preview content is loading, an animation or alternative graphic is shown to the user. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 . is a block diagram illustrating the relationship between a large networks and one embodiment of the system and method for direct marketing over a network of the present invention. FIG. 2 . illustrates a web-based email interface of an affiliate with a graphical link to the special promotions folder in one embodiment of the present invention. FIG. 3 a . illustrates an example of a list of promotions in a special promotions folder within the interface of a web-based email provider in one embodiment of the present invention. FIG. 3 b . illustrates an example of a preview triggered by the hovering of the mouse on top of an icon that serves as a triggering routine in one embodiment of the present invention. FIG. 3 c . illustrates an example of content within a promotion served in one embodiment of the present invention. FIG. 4 a . illustrates an example wherein promotions are placed within the same page as the listing of a subscriber's email in one embodiment of the present invention. The promotions includes a plurality of promotion types, such as direct marketing offers, email offers and search query offers. FIG. 4 b . illustrates an example of a preview of a promotion triggered by the hovering of the mouse on top of a triggering icon. FIG. 4 c . illustrates an example of a preview of a search query based offer triggered by the hovering of the mouse on top of a triggering icon. FIG. 4 d . illustrates an example of a search page of sponsored and non-sponsored search results, where certain sponsored listings may be listed in the embodiment of the invention in FIG. 4 c. FIG. 4 e . illustrates an example of a page that allows subscribers to customize the offers based they received based on a plurality of criteria such as favorite search terms, demographics, interests and geographical location. FIG. 5 . is a diagram explaining the processes performed in the preferred embodiments. FIG. 6 . is a flowchart of a software routine for a promotion issuer according to the preferred embodiment. FIG. 7 . depicts the flow of information in a system delivering online promotions to consumers according to the preferred embodiment. FIG. 8 . depicts the sequence of processes involved in displaying a listing of promotions to users of a web-based email provider according to the preferred embodiment. FIG. 9 . is a flowchart of a software routine for a web-based email user according to the preferred embodiment. DETAILED DESCRIPTION In FIG. 1 , The basic architecture of the network 10 comprises a plurality of affiliate web-based email (WebMail) sites 11 , the user's browser 24 , a promotions (promo) server web site 20 , and its supporting account management system 19 , storage 22 , and a optionally a plurality of print servers 23 . The architecture may include one or more affiliate Portal websites 13 which may be a news portal, financial portal or any other content or e-commerce based website familiar with one skilled in the art, one or more affiliate POP email provider's systems 15 , and one or more affiliate ISP custom user interface sites 17 . An example of an ISP custom user interface site is the AOL user interface which users have to launch in order to get online. Each affiliate system will include a client process 12 , 14 , 16 , 18 that is responsible for the integration and communication between the affiliate server processes 11 , 13 , 15 , 17 and the promotion server 23 . The discussion of the invention will now focus on the web-based email affiliate systems 11 , although it equally applies to the other affiliate systems 13 , 15 , and 17 . Overview FIG. 7 is an overview showing how the information and activities flow from the creation of the online promotion to its selection and printing by the consumer or central printing system and its ultimate redemption. The process starts with the promotions issuer 700 who creates the promotion (which may include coupons and certificates) and accompanying recipient targeting instructions and uploads them to the promotions server 701 which receives the instructions and content which are stored in storage. The web-based email user, through his PC 706 , logs in to the affiliate web-based email server 702 , to check for email and at the same time decides to check for promotions. The promotions client on the affiliate web-based email server 702 , sends information about the user (but not personally identifiable information like email or name) such as zip, age, online behavior profile, and personal preferences to the promotions server 701 to retrieve the targeted promotions. The data sent may include a generated ID of the user. This ID may be used to track a user's promotions redeeming behavior—however, the ID does not reveal the user's name or email address. The promotions server 701 serves up the promotions and logs the event in its records for billing and reports purposes. The promotions then get served to the user's PC 706 , wherein the user may save or print the promotion through an attached printer 707 . Alternatively, if a user has signed up for an enhanced service for coupons to be printed and mailed to the user, the promotions information will be passed from the promotions server 701 , to a central printing server 703 where the user's selected promotions and any additional relevant promotions may be included or printed through the attached printers 704 and mailed to the user. The kinds of additional promotions included in the package mailed to the user may depend on the user's past redeeming information if available, which is stored on the promotions server 701 . These additional promotions may include printed coupons not available electronically. In order to mail the promotions to the user, the user would have to agree to share his address and any personally identifiable information with the promotions service provider, which is sent with the promotion printing instructions from the promotions server 701 to the central printing server 703 . The electronically saved and printed promotions may contain the expiration date, a unique serial number and a barcode with the personal identification number (PIN) of the consumer. This identification data is preferably assigned by the promotions server 701 , the PIN number can be pre-assigned to individual consumers when they register for the system. Anytime before a promotion expiration date, the consumer may use one of two methods to redeem it. Firstly, the user may bring the printed promotions or coupon 705 , 709 to the store to 708 to redeem the promotion. Secondly, in the case of a promotion for an online offer, the user may redeem the electronic promotion by transmitting the electronically saved promotion coupon through the network to the merchant's web site. In other forms of promotions, the user may simply use the unique serial number of the promotion or coupon to redeem the offer. When the expiry date of a promotion is reached, the promotion will be automatically removed from the system. Information can also be passed back up through the system, first to the promotions server 701 , from the web-based email web-server 702 and then on to the promotions issuer 700 . Thus the promotions issuer can download information about the promotion results, consumer demographic information and cost. FIG. 5 shows the various components of the said invention in the preferred embodiment. It includes the affiliate web-based email provider's application 501 , email storage 507 and user profile storage 508 resident on the web-based email provider's server 500 . The promotions system includes the promotions client (promo) 502 , promotions serving application 503 , promotions account management application 505 , billing and tracking applications 506 , promotions storage 510 , promoter accounts storage 511 , and the proxy-user profile storage 509 —all resident on the promotions server 504 . User information is aggregated by the affiliate web-based email provider into distinct profiles 513 , which are stored in the provider's local storage 508 in a user profile table 512 . The table contains user identifiable personal information such as name, address and email, but only the profile information 513 is available to the promotions client 502 , in order to retrieve targeted promotions for a particular user on the web-based email system. In this case, a unique proxy ID 514 may also be generated by the web-based email application 501 which may be shared with the promotions client and is passed to the promotions server to create more targeted promotions based on usage patterns and preferences, as well as the ability for the user to save promotions. This information is stored in the proxy-user profile, history and preferences storage 509 . Web-based email users may subscribe to a premium service where the user can designate promotions and coupons to be printed and mailed to the user by a separate system. When users opt for this service, the proxy-user storage 509 also stores the user's email address, home address as well as other personally identifiable information. User Software Routine FIG. 9 displays the software routine for the consumer—in this embodiment the web-based email user. It starts 900 with a display of the web-based email provider's public home page 901 . The user logs in 902 and is presented with the main menu 923 . The user may check his email 903 upon which both a list of email 904 and a subset of promotions in his promotions folder 905 are displayed. The promotions may appear as a separate listing or integrated into the email listing itself 904 . The user may then choose to read his email 906 or to click on a link to check the promotions in his promotions folder 907 . The user may also opt to select a promotion directly from the inbox 904 . The user activates the promotion folder 907 by clicking a link from the main menu 923 or from his inbox 904 . The web-based email provider's application will interact with the promotions client, which interacts with the promotions server to display a list of promotions and their associated previews 908 . The user may select to view a promotion 909 . While viewing the list of promotions 908 or viewing a particular promotion 909 , the user may rate the promotion 910 to show his interest in the promotion or promotion type, forward the promotion to an email address 911 , save the promotion 912 to view or print at a later time, print the promotions or coupons 913 on a printer attached to his computer, or to select an option for the promotion or coupon to be printed and mailed 914 to his address. In certain cases, where the coupons are to be mailed directly from the promoter or merchant, the user will be prompted to release their personal identifiable information 915 such as home address to the promoter. From the main menu 923 the user may also search or browse for promotions 916 according to categories such as Automotive, Restaurants, Consumer Goods, Grocery, Services and Online Stores. The user may enter search criteria to locate merchants or promoters by name or location within a certain geographic zone. When the user executes the search or browses, the promotions client will send the queries to the promotions server wherein the results of the queries will be displayed 917 in the user's browser. To access more personalized promotions users may sign-up for a premium version of the promotions service (AdBox Plus) 918 , wherein the user will be prompted to agree to service terms 919 and then the user is prompted to enter personal identifiable information 920 such as name, address, zip, age, promotions preferences and email. The promotions server will log the user's personal information and service agreements in a database storage 921 . The enhanced personal information provided will allow the promotions system to send more targeted promotions to the user using techniques such as data mining. The promotions server may also combine this enhanced user information stored in the service storage 921 with other techniques such as user ratings of promotions 910 , to offer a more personalized experience for the user and provide a promoters with a more highly effective channel to promote their services or products. The user may also choose to perform other email functions 922 commonly offered within most web-based email services, such as address book, email filtering and email blocking. Offer Box in the Inbox FIG. 4 a shows another embodiment of the invention where promotional offers 405 are placed within the same page as the Inbox listing the subscriber's email 404 . This invention allows the ability to send offers to recipients based on their profile without cluttering the inbox with email offers. As the promotions in the “Offer Box” are rotated, the subscribers email space is not filled up. The Web-based email providers can now allow marketers to send Email Offers, Coupon Offers and other promotions to their recipients without the recipient having to pre-“opt-in” to receive offers in their email inbox as these promotions are not technically emails. Opening these offers may open the content of the offer or direct the recipients to a “landing page” of the website of the promoter. The Offer Box includes a plurality of offer types, such as Offers sent directly from the web-based email provider's advertising business 401 , Offers from outside marketers 402 , and offers based on the subscriber's previous search queries or preferences 403 . The subscriber may modify and customize the types of offers received by clicking on a link 407 to a customize offers page. These Offers may or may not have the dynamic preview capability attached to them depending on whether the marketer chooses to add the additional graphic or text for the preview. Offers and promotions with preview will appear with an icon 406 . FIG. 4 b shows an example of an embodiment of the invention wherein the user has his mouse over the triggering icon 411 for a promotional offer and a preview or “teaser” of a promotion is displayed 412 . FIG. 4 c shows an example of an embodiment of the invention wherein the user has his mouse over the triggering icon 421 for a search based offer and a preview of a text-based description of the offer is displayed 422 . In another embodiment not shown, the preview may be a graphic. The search based Offer 403 , is retrieved from either a local or 3 rd party based sponsored search listing as shown in FIG. 4 d . As shown in FIG. 4 d . the search query 431 produces a listing of sponsored (paid) 432 as well as non-sponsored 433 search results. Based on the users past queries, sponsored search results may be placed within the Offer Box 403 . The advantage of this aspect of the invention is that subscribers may only conduct a search once, but may be “in the market” for the items he searched for a brief period of time. Placing results in the Offer Box allows the subscriber to respond to new offers matching his search criteria without consistently repeating the same search requests. The search related offers in the Offer Box may be based on the recency and frequency of the user's search. Alternatively, the search related offers may be pulled from other sources other than sponsored listings, such as online retail businesses such as Amazon.com or auctions such as eBay. The present invention covers the aspect of placing search related offers in the Offer Box even without the preview capability/mechanism. FIG. 4 e shows an example of what the subscriber sees when he clicks on the “customize offers” link 407 . A plurality of criteria is used to target offers to subscribers. The criteria may include favorite search terms (or previous search terms) 441 , subscriber demographic information 442 , or categories of interest to the subscriber 443 . This information is compiled into a subscriber profile and is matched against potential offers. Details on the User Interface Processes As shown in FIG. 1 , the user will access his web-based email account using a browser 24 through a network to the affiliate web-based email web site 11 . The preferred embodiment of the network runs on top of TCP/IP and HTTP. Upon accessing the web-based email provider's web site 11 , the user logs on an will be presented with his email-box 200 , an example of which is featured in FIG. 2 . A prominent graphical link 201 , is placed within the interface of the web-based email interface 200 . The graphical link 201 , entices the user to check for promotions, which may be of interest to the user. Upon clicking on the graphical link 201 , the user will be shown the promotions folder 300 depicted in FIG. 3 a . In this embodiment, depending on the affiliate's preference, two different methods can be used to display the folder. In one method in FIG. 1 , the promotions folder will be served by the promotions client 12 resident on and integrated with the affiliate web-server 11 , and the other method, the promotions server 20 will serve the promotions folder over a network 10 . In the first method, the promotions client 12 will interact with the promotions server 20 to pull the content needed to generate the promotions folder and ensure the correct targeted promotions are shown to the user, whereas in the second method, the promotions server 20 will emulate a look and feel of the affiliate's website 11 and generate the promotions folder at the promotion server's 20 end. Promotions Preview Process The promotions folder 300 in FIG. 3 a will feature a plurality of promotions 301 listed either in date, name, category, distance or other criteria sorted order. Each line of the promotions listing 301 , will feature an icon 302 that will trigger the preview for that promotion. FIG. 3 b illustrates a diagram of a promotions folder 310 , wherein the user has his mouse hovered over a preview triggering icon 311 , where the preview for the promotion is currently visible (active) 312 . The preview 312 will automatically disappear (deactivate) after a set period of time, after the user has moved his mouse away from the triggering icon 311 , or when the user movies his mouse to the triggering icon 311 of another promotion. The method to perform the preview involves the JavaScript browser scripting technology and Dynamic HTML (DHTML), wherein, the preview is a DHTML layer manipulated by JavaScript. In the specific embodiment of the invention, a hidden HTML layer is created for each of the entries to place the preview content in when the user activates the triggering mechanism. This is achieved using the <DIV> </DIV> tags and setting the position style variable to “absolute” and visibility style variable to “hidden” and when the trigger is triggered, the visibility variable is set to “visible” thus showing the hidden preview content. Alternative embodiments may use only one hidden HTML layer that is shared between different previews or any other methods to achieve the overlay or sliding out effect familiar to those skilled in the art such as the use of IFRAMES and Java applets. Specifically, in this preferred embodiment of the invention, each preview 312 is keyed to appear directly under the listing of the promotion 313 , appearing like a drop-down layer sliding out from under the promotion listing. Other preview methods may include an animated graphic moving across the current browser window with accompanying audio. Also in order to prevent accidental triggering, in a specific embodiment of the invention, delays are introduced in the preview triggering mechanism to ensure that the user has his mouse over the preview trigger a specific period of time before the preview is actually triggered and shown to the user. To allow the user some leeway, a delay is also introduced before the preview is hidden after the user has moved his mouse away from the preview trigger or preview content layer. The total payload of all the previews in the promotions folder 310 listing may be quite huge, thus slowing down the overall loading of the promotions folder. This effect is mitigated by ensuring that the initial loading of the page does not include the loading of the “heavy” objects in the preview content, such as graphics. One method to achieve this is to initially put in lightweight content or images in place of the heavyweight graphical preview content 312 , during the serving of the promotions folder (in the HTML code), then triggering the loading of the heavyweight graphical preview 312 , by a JavaScript code after the promotions folder page has finished loading to the user's browser. The JavaScript code will load the heavyweight graphical previews from the promotions server, and replace the lightweight content or images with the heavyweight content before the previews 312 are shown. Another method to achieve a “fast load” of the promotions folder 310 is to activate the loading of the heavyweight content only after the user has triggered the preview loading routine 311 . This method may result in the user being subjected to a delay in the loading of the preview. In this embodiment of the invention, both methods are used. The preferred embodiment of the invention further includes the ability to load preview content using a predictive loading algorithm to determine the order in which preview content are loaded in the background. The algorithm may take into account the priority given to the promotion and the size of the preview content. In addition, the algorithm may load previews based on the real-time triggering pattern of the previews by the user, which may include the proximity of not-yet-loaded previews from previously viewed and loaded previews. An example would be when the user triggers a preview 314 , any not-yet-loaded previews 315 in close proximity to the triggered preview 314 would be loaded in the background. Another suggested enhancement to this feature is to take advantage of the Keep-Alive feature of the HTTP protocol (persistent HTTP) wherein a series of requests for content can be made on a single TCP/HTTP connection to the promotions server allowing the content to be loaded faster. Other methods to achieve dynamic loading may include using technologies such as Flash and Java or other routines familiar to those skilled in the art, wherein the preview content may be streamed to the browser giving the user an impression that the content is loading quickly. In cases where the network is slow and there is considerable delay loading a preview after a user has activated the preview trigger, a routine is executed to delay the appearance of the preview until the preview has completely loaded. During this delay, an animation can be shown to signal to the user that the content is currently loading. FIG. 3 c depicts an example of a body of a promotion. The promotion page 320 consists of the promotion content and associated coupons 321 , options (links) for the user to print, have the coupon mailed to him, to save the coupon to be viewed later, to forward the coupon to an email address and an option to be reminded to use the coupon at a later date 322 . The promotion page also consists of links to applications such as mapping directions and store locators 323 . These applications can either be hosted locally at the promotions server, or be integrated over the network with an external mapping or locator service such as MapQuest. FIG. 8 traces the sequence of processes executed between the time the user logs in 800 to the web-based email system until the promotions folder (Ad Box) is displayed to the user 806 . The user logs in to the web-based email system 800 wherein the web-based email server authenticates the user 801 and a token 802 is sent to the browser identifying that the user has logged in. This token may be a cookie or any other secure mechanism familiar to those skilled in the art. The web page showing that the user has logged in is displayed to the user 803 . During this time, the promotions client receives data from the web-based email server, which may include demographics information or a composite or proxy ID of the user. This information is then sent across the network to promotions server to create the content of the user's promotions folder 804 . The process to create the content of the user's promotions folder 804 , includes using the demographics and any other information about the user's preference and historical behavior to select relevant promotions for the user. This process 804 may be performed in real-time. In cases where a proxy ID (an ID generated by the web-based email provider, not revealing any private user's information such as email) is used, a database entry may be created for each user on the promotions server to store relevant promotions for the user. In the case where the proxy ID is used, the promotions folder may simply be the process of retrieving the promotions keyed in the user's promotions table in the database. Other algorithms familiar to those skilled in the art may be used to create the promotions folder. The promotions served are then tracked and logged 805 for billing purposes and the promotions folder page is assembled by the promotions client and displayed to the user. Promoter Software Routine FIG. 6 displays the software routine for the promoter. It starts 600 with a display of the web-site portal of the promotions server. At the website, the promoter may choose to sign up 603 and create an account with the service provider wherein the promoter will enter his payment options 604 such as credit card, invoice billing, or through an online service such as PayPal. From the main page of the portal, a registered promoter may log-in to the site 602 by authenticating himself, either by using a user ID and password or by other authentication mechanisms familiar with those skilled in the art. After the promoter has been authenticated, the promoter will be shown the main menu 621 , where he will be able to create new promotions. To create a new promotion, the promoter will use the system to browse templates of promotions 605 , these templates are visual and content promotion templates wherein, the structure of the promotions are fixed and the user needs only to populate certain areas within the template to develop a complete promotion. After selecting the template, the promoter then proceeds to enter details about the promotion 606 , such as the coupons, offers, graphical elements, expiry date, promotional codes and text. The promoter is then prompted to enter targeting parameters for the promotion 607 . Targeting parameters may include demographics information such as zip, age, and country, behavioral and user preferences information, preferred web-based email provider network, and the amount of promotions to deliver. The amount of promotions may include the number of impressions (times) the promotion is shown, the number of users or web-based email accounts the promotions are delivered to, or the number and types of profiles used in targeting the recipients of the promotion. Finally, the promoter will be presented with the cost of the promotion 608 , upon which the promoter may select different payment options, such as credit card, invoice, or through an online payment service 608 . When the user has completed the transaction, the promotion and billing information will be stored in storage 609 . From the main menu 621 , the promoter may also display results of current or past promotions 610 . From the list of promotion results 610 , the promoter may choose to reuse an old promotion to create a new promotion 611 . The promoter may also view detailed reports 612 including billing 613 and statistics information of past promotions 614 , which may reveal such information as what kinds of recipients read or opened the promotion and which zip constituted the most response. The system also allows promoters to conduct splits, the practice of sending different ads to different recipients of the same population. For example two different ads may be sent to 20,000 recipients living in the same zip code, split 50/50 among the population—10,000 recipients receiving one version of the ad and the other 10,000 receiving the other version. This method allows the promoter to gauge the effectiveness of the ad by looking at the results each version of the ad garnered. The promoter will be able to enter these parameters in the promotion-targeting page 607 and view the results in the promotion statistics page 614 . From the main menu 621 , the promoter may display current running promotions 615 and make modifications to them 616 . From the main menu, 621 , the promoter may search for promotion designers 617 , create a contract with the designer 618 , give privileges to the designer to access certain portions of their accounts in the site to create promotions 619 , and pay the designer 620 . Detailed Description of the Second Preferred Embodiment The second preferred embodiment of the invention is similar to the first preferred embodiment, except that in FIG. 1 , the Promotions (Promo) Server 20 , Account Management Server 19 and Storage 22 , are hosted and managed at the web-based email (WebMail) provider's web-site 11 location and managed by the web-based email provider. The system may also be deployed in other registration based websites such as Portals and content based sites. Conclusion In the foregoing specification, the invention has been described with reference to specific exemplary embodiments thereof. Other embodiments will be apparent to those of ordinary skill in the art. For example, the preview mechanism may be integrated into non-web based email email providers. It may be integrated into a proprietary email interface such as AOL or it may be integrated into Outlook as an ActiveX plugin. The preview mechanism may also be integrated into email applications designed for mobile devices such as cellular phones and PDAs.

An online direct marketing and advertising system is presented in which advertisers have an opportunity to send targeted promotions, coupons and offers that are placed in a user's web-based email account without the drawbacks of sending conventional email. The promotions do not take up disk quota space and, at the same time, the system does not need to divulge private user information to the advertiser. This system provides a means to free web-based email providers from the need to obtain opt-in permission to send offers to their users as providers are frequently prohibited from sharing the user's email address and personal information with merchants.

BACKGROUND OF THE INVENTION I. Field of the Invention The present invention relates generally to antennas. More particularly, the present invention is directed to a novel and improved variable length whip and helix antenna system for use in a portable communication device. II. Description of the Related Art Portable communication devices, such as portable radiotelephones, typically employ a simple dipole whip antenna as the main antenna. This antenna is usually retractable to make the unit more compact when a call is not in progress. However, when the whip antenna is retracted within the portable radiotelephone housing, the efficiency of the antenna is substantially reduced due to the presence of conductive objects in the antenna pattern. Several prior art antenna systems attempt to compensate for these object-induced nulls in the whip antenna pattern. For example, some prior art portable radiotelephones utilize a compact helical antenna as an auxiliary antenna, with the main whip antenna extending through the center of the helix. In these prior art portable radiotelephones, the helical antenna remains exposed while the main antenna is retracted within the radiotelephone housing. As such, the helical antenna is able to receive and transmit radio frequency (RF) signals even though the main antenna is retracted. However, since the main whip antenna extends through the center of the helical antenna, there may be RF coupling between the helical antenna and the whip antenna when the helical antenna is in use, i.e. when the whip antenna is retracted. This coupling results in an undesirable loss of efficiency of the helical antenna. Some prior art antenna systems attempt to avoid this undesirable loss of efficiency due to coupling by fabricating a whip antenna in which a substantial length of the top portion of the whip antenna is constructed of a non-conductive material, such as plastic. Such a prior art antenna system 100 is illustrated in FIGS. 1A and 1B. In FIG. 1A, prior art antenna system 100 is seen to comprise a whip antenna 102 and a helical antenna 104. Whip antenna 102 comprises a conductive portion 108 and a non-conductive portion 110. Helical antenna 104 is typically encased in a dielectric housing 106 which is external to portable radiotelephone housing 150. In FIG. 1A, whip antenna 102 is fully extended, exposing conductive portion 108. In this position, helical antenna 104 surrounds the bottom of conductive portion 108. In FIG. 1B, whip antenna 102 is fully retracted, and helical antenna 104 receives and transmits RF signals. In this position, helical antenna 104 surrounds the non-conductive portion 110 of whip antenna 102. Since the non-conductive portion 110 does not couple signal energy from helical antenna 104, the undesirable loss in efficiency by parasitic coupling of whip antenna 102 described above is avoided. However, a problem with the prior art solution described above is that when whip antenna 102 is in the extended position as shown in FIG. 1A, helical antenna 104 has an unintended effect on the antenna pattern of whip antenna 102. Some of the energy intended to be radiated through whip antenna 102 is coupled to helical antenna 104. In many applications, this parasitic coupling by the helical antenna 104 is undesirable and inefficient in much the same way as the parasitic coupling by the whip antenna 102 as described above. Another problem with the prior art solution as shown in FIGS. 1A and 1B is that the length of whip antenna 102 must be increased to incorporate non-conductive portion 110. This results in an overall antenna length that is greater than is necessary for whip antenna 102 to perform efficiently. When whip antenna 102 is extended, the non-conductive portion 110 serves no functional purpose, increasing the physical antenna length without increasing the antenna electrical length. This extra length adds size, cost and weight to the portable radiotelephone 150. What is needed is a combination whip/helix antenna system which operates efficiently whether the whip antenna is extended or retracted, and in which the length of the whip antenna is independent of coupling considerations with the helical antenna. SUMMARY OF THE INVENTION The present invention is a novel and improved antenna system for a communication device. In the preferred embodiment, a whip antenna is surrounded by a helical antenna. The preferred embodiment of the antenna system further comprises a mechanical switch which couples the helical antenna to the signal source when the whip antenna is in a retracted position. The whip antenna is comprised of an upper conductive portion, a lower conductive portion, and an intermediate dielectric portion connected between the upper and lower conductive portions and isolating the upper and lower conductive portions from each other. A conductive sleeve member also surrounds the whip antenna and is slidably mounted thereon. In a first embodiment, the helical antenna and the conductive sleeve member are two separate elements, with the helical antenna being fixedly mounted to the housing of the communication device. In this first embodiment, when the whip antenna is extended, the conductive sleeve member slides over the dielectric portion, coupling the upper and lower conductive portions together. As the whip antenna is retracted, the helical antenna pushes the conductive sleeve member to the top end of the whip antenna, isolating the whip antenna from the helical antenna. Furthermore, when the whip antenna is retracted, the mechanical switch couples the helical antenna to the signal source. In a second embodiment, the helical antenna is an integral part of the conductive sleeve member. In this second embodiment, when the whip antenna is extended, the conductive sleeve member containing the helical antenna slides over the dielectric portion, coupling the upper and lower conductive portions together through the helical antenna element. The resulting antenna structure is a single radiating element having a lower whip-like conductive portion, an intermediate helical conductive portion, and an upper whip-like conductive portion. As the whip antenna is retracted, the housing of the communication device pushes the conductive sleeve member containing the helical antenna to the top end of the whip antenna, thereby isolating the whip antenna from the helical antenna. Furthermore, when the whip antenna is retracted, the mechanical switch couples the conductive sleeve member containing the helical antenna to the signal source. In both of the above embodiments, since the conductive sleeve member couples the upper and lower conductive portions together when the whip antenna is extended, the physical length of the whip antenna is dictated only by the desired electrical length, and not by adverse RF coupling considerations. Furthermore, when the whip antenna is retracted, it does not adversely affect the antenna gain pattern of the helical antenna. BRIEF DESCRIPTION OF THE DRAWINGS The features, objects, and advantages of the present invention will become more apparent from the detailed description set forth below when taken in conjunction with the drawings in which like reference characters identify correspondingly throughout and wherein: FIG. 1A is an illustration of a prior art antenna system in which the whip antenna is extended; FIG. 1B is an illustration of the antenna system of FIG. 1A in which the whip antenna is retracted; FIG. 2A is an illustration of a first embodiment of the antenna system of the present invention with the whip antenna extended and the sleeve member in cut-away view; FIG. 2B is an illustration of the antenna system of FIG. 2A with the whip antenna retracted and the sleeve member in cut-away view; FIG. 3A is an illustration of an exemplary portable radiotelephone, shown in partially cut-away view, employing the first embodiment of the antenna system of the present invention with the whip antenna extended; FIG. 3B is an illustration of an exemplary portable radiotelephone of FIG. 3A with the whip antenna retracted; FIG. 4A is an illustration of a second embodiment of the antenna system of the present invention with the whip antenna extended and the sleeve member in cut-away view; and FIG. 4B is an illustration of the antenna system of FIG. 4A with the whip antenna retracted and the sleeve member in cut-away view. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the antenna system 200 of the present invention as shown in FIGS. 2A and 2B comprises a whip antenna 202 inserted longitudinally through the center of helical antenna 204. Helical antenna 204 is preferably encased in a dielectric casing 206 such as plastic, and is mounted externally on portable radiotelephone housing 250 by means known in the art; for example, by a threaded insert (not shown). Whip antenna 202 may be extended as shown in FIG. 2A, or retracted within portable radiotelephone housing 250 as shown in FIG. 2B. In this first embodiment, regardless of whether whip antenna 202 is extended or retracted, helical antenna 204 remains mounted externally on housing 250. When whip antenna 202 is extended as shown in FIG. 2A, the helical antenna 204 is preferably not used, although it may be used to intentionally augment or alter the antenna gain pattern of whip antenna 202. In order to switch out helical antenna 204 when whip antenna 202 is extended, a variety of electrical or mechanical switches may be used. For example, in FIGS. 2A and 2B, a feed point 220 of helical antenna 204 extends downwardly from the coils of helical antenna 204. As can be seen from FIG. 2B, when whip antenna 202 is in a retracted position, feed point 220 is contacted by a spring arm 222 which provides signals to and from the radiotelephone's transceiver (not shown). Spring arm 222 is held securely against feed point 220 by a lateral spring force. However, when whip antenna 202 is in an extended position as shown in FIG. 2A, a widened portion 224 at the bottom of whip antenna 202 engages spring arm 222, pushing spring arm laterally away from feed point 220 and electrically de-coupling spring arm 222 from helical antenna feed point 220. By switching out helical antenna 204 when whip antenna 202 is extended, one may avoid undesirable alterations or inefficiencies in the antenna gain pattern of whip antenna 202 when it is extended. In another aspect of the first embodiment of the present invention, whip antenna 202 comprises an upper conductive portion 209, a lower conductive portion 208, and an intermediate dielectric portion 210. A sliding sleeve member 211 surrounds whip antenna 202 and is slidably mounted thereon. In this first embodiment, sleeve member 211 is made of a conductive material, such as copper, steel or the like, and optionally may be outwardly encased in a protective dielectric material such as plastic (not shown). Also, although helical antenna 204 is illustrated in FIG. 2A and 2B as a proper helix, it may also be of other construction as is known in the art; for example a solid cylinder, a braided mesh, or a loop antenna. Likewise, whip antenna 202 may be of various constructions, such as telescopic or fixed length. Both upper and lower conductive portions 209, 208 are constructed from metallic materials as are known in the art. Also, intermediate dielectric portion 210 is preferably constructed of a strong plastic, but may alternately be made of any non-conductive composite dielectric material as are known in the art. When whip antenna 202 is extended from the portable radiotelephone housing 250 as shown in FIG. 2A, sleeve member 211 couples upper conductive portion 209 to lower conductive portion 208, thus bypassing intermediate dielectric portion 210 and providing electrical continuity throughout the length of whip antenna 202. In this extended position, whip antenna 202 conducts RF signals throughout its length. Current oscillates in whip antenna 202 through conductive portion 208, sleeve member 211, and upper conductive portion 209, enabling whip antenna 202 to transmit and receive RF signals using its entire physical length. As was previously mentioned, when whip antenna 202 is extended as shown in FIG. 2A, helical antenna 204 may be switched out by the engagement of widened portion 224 with spring arm 222. In addition to switching out helical antenna 204, spring arm 222 may also be used to couple whip antenna 202 to the radiotelephone's transceiver (not shown) if widened portion 224 is made of a conductive material, or is an integral part of lower conductive portion 208. In such an embodiment, spring arm 222 would conduct RF signals to and from whip antenna 202 through widened portion 224 when whip antenna 202 is in the extended position shown in FIG. 2A, and would conduct RF signals to and from helical antenna 204 through feed point 220 otherwise, for example, when whip antenna 202 is in the retracted position shown in FIG. 2B. In the first embodiment shown in FIGS. 2A and 2B, sleeve member 211 is a metallic cylinder having an inward turned "lip" or taper at each end for contacting the upper and lower conductive portions 209, 208. Alternatively, sleeve member 211 may be a "clip" arrangement which does not completely surround whip antenna 202. Optionally, an upper lip of sleeve member 211 also engages sleeve stop 212. Sleeve member 211 physically rests against sleeve stop 212 when whip antenna 202 is in the extended position illustrated in FIG. 2A. Sleeve stop 212 may be a "bump" on the upper conductive portion 209 as shown, or it may be a mere widening or flare of upper conductive portion 209. Alternatively, sleeve stop 212 may be an integral part of lower conductive portion 208 as is shown in FIGS. 2A and 2B. Clearly, there are may different ways to physically suspend sleeve member 211 such that it bridges intermediate dielectric portion 210, coupling upper conductive portion 209 to lower conductive portion 208. When whip antenna 202 is retracted substantially within portable radiotelephone housing 250 as shown in FIG. 2B, sleeve member 211 is pushed to the top of whip antenna 202, de-coupling upper conductive portion 209 from lower conductive portion 208, and allowing intermediate dielectric portion to electrically isolate upper conductive portion 209 from lower conductive portion 208. In this retracted position, helical antenna 204 is isolated from lower conductive portion 208 by the physical distance of intermediate dielectric portion 210. As such, RF signals received and radiated by helical antenna 204 are not coupled to the entire length of whip antenna 202, although there may be some negligible coupling to sleeve member 211 and upper conductive portion 209. In the first embodiment shown in FIG. 2B, sleeve member 211 has an outer diameter smaller than the inner diameter of helical antenna 204, and thus slides in between upper conductive portion 209 and helical antenna 204 when whip antenna 202 is in the retracted position. The sliding of sleeve member 211 as whip antenna 202 is moved from the extended position of FIG. 2A to the retracted position of FIG. 2B may be arrested by engaging a lower lip on sleeve stop 212. Alternatively it may be arrested by engaging an upper lip on a widened upper end of upper conductive portion 209. Based on the length of sleeve member 211 and the size and location of intermediate dielectric portion 210 along the length of whip antenna 202, one may design many different schemes as are known in the art for limiting the travel of sleeve member 211 along the length of whip antenna 202. FIGS. 3A and 3B illustrate a partially cut-away view of the first embodiment of the antenna system 200 of the present invention employed by a portable radiotelephone 250 suitable for use with the present invention. When whip antenna 202 is in the extended position of FIG. 3A, spring arm 222 engages widened portion 224, switching out the helical antenna encased in dielectric housing 206. Also, sleeve member 211 (here shown as a metallic cylinder with a lip at a top end) couples upper conductive portion 209 to lower conductive portion 208, providing for full electrical continuity along the length of whip antenna 202. When whip antenna 202 is in the retracted position of FIG. 3B, spring arm 222 connects to the helical antenna encased in dielectric housing 206. Also, sleeve member 211 slides to the top of upper conductive portion 209, thus de-coupling upper conductive portion 209 from lower conductive portion 208. In this position, the upper conductive portion 209 of whip antenna 202, and the helical antenna encased in dielectric housing 206 are isolated from lower conductive portion 208 by intermediate dielectric portion 210. In this first embodiment of the present invention, spring arm 222 provides for the reduction of parasitic coupling by helical antenna 204 (see FIGS. 2A and 2B) when whip antenna 202 is extended, while sleeve member 211 provides for the reduction of parasitic coupling by whip antenna 202 when whip antenna 202 is retracted. Furthermore, sleeve member 211 allows the full physical length of whip antenna 202 to be used for receiving and radiating RF signals, without adding the additional length required in the prior art antenna system shown in FIGS. 1A and 1B. Thus, the physical length of whip antenna 202 in the present invention is independent of adverse coupling considerations found in the prior art antenna systems. Additionally, sleeve member 211 adds negligible size and weight to the phone, and may be compactly stored within helical antenna 204 when whip antenna 202 is retracted. A second embodiment of the antenna system 200 of the present invention is illustrated in FIGS. 4A and 4B. This second embodiment is similar to the first embodiment in that sleeve member 211 couples upper conductive portion 209 to lower conductive portion 208 when whip antenna 202 is in the extended position as shown in FIG. 4A. However, in contrast to the first embodiment, helical antenna 204 is not fixedly mounted to the housing of portable radiotelephone 250. In this second embodiment, helical antenna 204 is an integral part of sleeve member 211, and current actually flows through helical antenna 204 when whip antenna 202 is in the extended position. Preferably, in this second embodiment, with the exception of helical antenna 204, sliding sleeve member 211 is a non-conductive dielectric plastic material. Thus, when whip antenna 202 is extended, the resulting radiating element comprises a whip-like lower conductive portion 208, the intermediate helical conductive portion of helical antenna 204 encased in sleeve member 211, and the upper conductive portion 209. When whip antenna 202 is in this extended position, helical antenna 204 behaves like a phasing coil, extending the electrical length of whip antenna 202, while concentrating its radiating pattern along the horizontal plane. Alternatively, sleeve member 211 may still be a conductive material, however this would obviate the need for the helical antenna 204, and the sleeve member 211 would merely act as a cylindrical radiator. When whip antenna 202 is retracted as shown in FIG. 4B, sleeve member 211 and integral helical antenna 204 are pushed to the top of whip antenna 202, but remain exposed externally to portable radiotelephone housing 250. However, feed point 220 of helical antenna 204 extends internally into portable radiotelephone housing 250 to make electrical contact with spring arm 222. Thus, when whip antenna 202 is retracted, this second embodiment behaves similarly to the first embodiment of FIGS. 2A and 2B with helical antenna 204 acting as the primary radiator, while still isolating lower conductive portion 208 from whip antenna 204 by intermediate dielectric portion 210. Alternatively, feed point 220 may be directly coupled to sleeve member 211 if sleeve member 211 is made from a conductive material. In such a case, the sleeve member 211 would act as a cylindrical radiator. The previous description of the preferred embodiments is provided to enable any person skilled in the art to make or use the present invention. The various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without the use of the inventive faculty. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

An antenna system for a communication device. A whip antenna is surrounded by a helical antenna. A switch couples the helical antenna to the signal source when the whip antenna is in a retracted position. The whip antenna is comprised of an upper conductive portion, a lower conductive portion, and a dielectric portion which isolates the upper and lower conductive portions from each other. A conductive sleeve member surrounds the whip antenna and is slidably mounted thereon. In a first embodiment, when the whip antenna is extended, the conductive sleeve member slides over the dielectric portion, coupling the upper and lower conductive portions together. As the whip antenna is retracted, the helical antenna pushes the conductive sleeve member to the top end of the whip antenna, isolating the whip antenna from the helical antenna. In a second embodiment, the helical antenna is an integral part of the conductive sleeve member.

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application Ser. No. 61/662,990, filed Jun. 22, 2012, which is incorporated by reference in its entirety. FIELD OF THE INVENTION [0002] This invention relates to an aqueous dispersion of waxes, polymers, pigments and other functional additives, and its use as a concentrate of eye make-up compositions. BACKGROUND OF THE INVENTION [0003] Mascara formulation is usually a viscous emulsion with ingredients such as waxes, emollients, pigments and film formers. In the production process, waxes, fatty acids and emollients are mixed and heat to 80-90° C. to melt and dissolve the waxes. Pigments and emulsifier then are added and dispersed in this oily mixture. Hydrophilic thickeners like gums or synthetic polymers are dispersed in hot water. Some of them require neutralization. This second phase is heated and combined with the oily phase to form the emulsion. [0004] Mascara and eyeliner formulations incorporate anionic soaps and non-ionic emulsifiers, such as glycerides and fatty alcohols. Their primary function is to emulsify waxes to sub-micron size and stabilize the Particles. [0005] However, emulsifiers can reduce the desired water-proofness because they cause films on lash to dissolve due to their hydrophilic nature. Some emulsifier can also be a source of skin and eye irritation. Many of the common emulsifiers for mascaras and eyeliners have regulatory issues and remain as questionable for the future, especially in Europe. Non ionic systems are preferred by many cosmetic companies. Less emulsifier provides better performance. [0006] The conventional manufacturing necessitate the heating and precise cooling, two sets of heating tanks and mixers. This not only incurs energy cost but also extends the production time because some processes cannot proceed until a certain temperature is reached. [0007] Moreover, processing, weighing, quality control and inspection of raw materials for a typical conventional process add the cost significantly. The quality assurance involves many aspects. In the current trend of cost-cutting, in order to remain competitive in the marketplace, it is desired to have a concentrate in the formulation process as a single component that contains all keep ingredients at an optimized ratio. [0008] Aqueous mascaras are wax-in-water emulsions that produce sub-micron Particles of waxes. Waxes are known to be melted and then emulsified to form wax-in-water emulsions which may then be used to produce both mascara and eyeliner products. Waxes are seldom added directly to an aqueous phase. EP394078 disclosed a cosmetic composition for hair treatment containing a microdispersion of wax in water using ionic or non-ionic emulsifier. U.S. Pat. No. 5,849,278 disclosed an eye makeup composition comprises an aqueous dispersion of wax Particles, at least one water-soluble film-forming polymer and pigments, the said dispersion being a microdispersion of colloidal wax Particles. The inventor claim that the addition of water-soluble film-forming polymers help the formula to exhibit remarkable qualities of regular and smooth deposits on the eyelashes. US20110250148 (A1) disclosed water dispersible wax powders for cold process emulsification. Water soluble polymers such as sodium polyacrylate are used to form a composite with waxes and help to dispersion the wax at room temperature. However, the water-soluble polymer can lead to a poor water resistance of the final eye make-up composition. SUMMARY OF THE INVENTION [0009] It is an object of this invention to provide an aqueous dispersion of waxes, polymers, pigments and other functional additives, which can be used as a concentrate of an eye make-up composition. [0010] It was discovered, in a surprising manner, that when the all Particulate ingredients such as pigments, functional filler are incorporated to a solid loading of 70%, no additional emulsifier is needed to maintain the stability. Both the concentrate and dilutions of this technology to form mascaras & eyeliners have improved water-resistance over conventional products. [0011] In one aspect, the present invention provides a dispersion composition comprising one or more waxes, one or more water-insoluble film-forming polymers, one or more pigments and other functional additives, wherein said dispersion has a viscosity in the range of about 150,000 cPs. to about 800,000 cPs. at about 25° C. and comprises at least about 60% of solids by weight. [0012] In one embodiment of this aspect, the dispersion composition is an aqueous dispersion, optionally containing an organic solvent. [0013] It is another object of this invention to provide a process for manufacturing the said dispersion using a cold process or a low heat process when the temperature is below the melting point of the wax. [0014] In another aspect, the present invention provides a method of making a dispersion composition as described herein, the method comprising: [0015] a) adjusting a polymer emulsion or dispersion with a base to a desired pH; [0016] b) adding one or more waxes to the polymer emulsion or dispersion under agitation; [0017] c) adding one or more functional additives to the mixture under agitation; and [0018] d) adding one or more preservatives under agitation. [0019] In another aspect, the present invention provides a method of making an eye composition, comprising: [0020] a) mixing one or more diluents with one or more preservatives to form a mixture; [0021] b) adding a dispersion composition according to any embodiments described herein and mixing till uniform; and [0022] c) filling with mixture obtained in b) with one or more filler materials. [0023] In preferred embodiments, no heating, cooling or homogenization is applied in the manufacturing processes. [0024] It is still another object of this invention to provide a method for making final eye makeup formulation from the above concentrated dispersion. Thus, in another aspect, the present invention provides rub-resistant and water-resistant mascara incorporating a dispersion composition according to any embodiment described herein. [0025] These and other aspects of the present invention will be better appreciated by reference to the following detailed description and claims. DETAILED DESCRIPTION OF THE INVENTION [0026] This invention provides an aqueous dispersion of waxes, polymers, pigments and other functional additives, which can be used as a concentrate of an eye make-up composition. [0027] In one aspect, the present invention provides a dispersion composition comprising one or more waxes, one or more water-insoluble film-forming polymers, one or more pigments and other functional additives, wherein said dispersion has a viscosity in the range of about 150,000 cPs. to about 800,000 cPs. at about 25° C. and comprises at least about 60% of solids by weight. [0028] In one embodiment of this aspect, the dispersion composition is an aqueous dispersion, optionally containing an organic solvent, such as alchol (e.g., EtOH, isopropanol, or the like), or glycols, such as Caprylyl Glycol, Hexylene Glycol, or the like. [0029] In another embodiment of this aspect, the one or more waxes comprise a plurality of wax particles. [0030] In another embodiment of this aspect, the one or more waxes have particle sizes in the range of about 0.5 microns to about 50 microns (0.5-50 μm) in diameter. [0031] In another embodiment of this aspect, the one or more waxes have particle sizes in the range of about 2 microns to about 10 microns (2-10 μm) in diameter. [0032] In another embodiment of this aspect, the one or more waxes are independently selected from natural waxes. [0033] In another embodiment of this aspect, the natural waxes comprise Carnauba wax, Candellila wax, Alfa wax, and Beeswax. [0034] In another embodiment of this aspect, the one or more waxes are independently selected from synthetic waxes. [0035] In another embodiment of this aspect, the synthetic waxes comprise polyethylene and microcrystalline waxes. [0036] In another embodiment of this aspect, the one or more waxes comprise both synthetic and natural waxes. [0037] In another embodiment of this aspect, the one or more waxes are present in the form of particles comprising a composite of synthetic and natural waxes. [0038] In another embodiment of this aspect, the particles of said one or more waxes are in the range from about 1% to about 30% by weight of the total composition. [0039] In another embodiment of this aspect, the one or more water-insoluble film-forming polymers are emulsion of synthetic polymer emulsion or dispersion. [0040] In another embodiment of this aspect, the one or more water-insoluble film-forming polymers are in the range of about 1% to about 30% by weight of the total composition. [0041] In another embodiment of this aspect, the one or more water-insoluble film-forming polymers are independently selected from acrylate polymers or copolymers, polyurethanes, polyvinyl acetate and copolymers, styrene-butadiene copolymers, vinyl acetate-ethylene copolymers. [0042] In another embodiment of this aspect, the one or more pigments are in the range of from about 2% to about 50% by weight of the total composition. [0043] In another embodiment of this aspect, the one or more additive fillers comprise particulate materials. [0044] In another embodiment of this aspect, the additive fillers are in a form selected from microspheres and fibers. [0045] In another embodiment of this aspect, the microsphere has a size of about 1 μm to about 50 microns (1-50 μm) in diameter. [0046] In another embodiment of this aspect, the microsphere is made from a mineral or polymeric material. [0047] In another embodiment of this aspect, the fibers have a length in the range from about 0.1 mm to about 10 mm (0.1-10 mm) and a thickness in the range from about 0.5 denier to about 10 denier (0.5-10 D). [0048] In another embodiment of this aspect, the fibers are made from a synthetic polymer or natural fibers. [0049] In another embodiment of this aspect, the synthetic polymer is selected from Nylons. [0050] In another embodiment of this aspect, the natural fiber is silk. [0051] In some embodiments, the dispersion of the present invention can be used as is, or diluted with water and some aqueous gel to make regular mascara, or can be diluted much further to make an eye liner composition. [0052] In some embodiments, the composition contains a latex (aqueous emulsion or dispersion of polymer) at 5-50% by solids. Suitable latex includes acrylic latex, natural latex, any dispersion or emulsion of synthetic polymer. Examples of acrylic latex are Daitosol 5000SJ, Daitosol 5000AD from Daito Kasei Kogyo. The latex may need to be neutralized before mixing with other ingredient. [0053] In some embodiments, the composition contains micronized wax powders. Suitable waxes are natural waxes such as Carnauba wax, Beeswax, Ozokerite or synthetic waxes such as polyethylene, microcrystalline wax, etc. The wax can also be a mixture of natural and synthetic waxes. The wax powder can have any shape, irregular, granular or spherical. The mean sizes of these powders are in the range of 0.5-50 microns, but preferably, 2-10 microns. [0054] In some embodiments, the composition contains pigments such as iron oxides, ultramarines, titanium dioxide, and Black No. 2 (carbon black). The pigments can also be water dispersible lakes of organic dyes. It is preferred that the pigment be pre-dispersed in water and milled to achieve full color strength. [0055] In some embodiments, the composition may also contain other functional filler to improve its performance. Microspheres with a mean size of 3-50 microns, preferably, 5-20 microns, can be used to provide volumizing effect. The micropsheres can be made from synthetic or natural polymers such as PMMA (SUNPMMA-S from Sunjin), Cellulo Bead from Daito Kasei, or, from inorganic substrate such as silica (MSS-500/20N, MSS-500/N from Kobo). [0056] In some embodiments, the fiber can be added to the dispersion to provide lengthening effect. Suitable fibers are natural fiber such as Cell-u-Lash from Kobo and synthetic fiber such as Nylon Cut Fiber 3D (Kobo/Jigen International) [0057] In some embodiments, the aqueous thickeners can be used to stabilize the dispersion. The thickeners can be natural gum like xanthan gum or synthetic clay, such as bentonite. [0058] The production process for enabling cosmetic manufacturers (see, e.g., Examples 6-13) involves only mixing at room temperature with a Cowles Mixer or the equivalent. No heating or homogenization is needed. [0059] In another aspect, the present invention provides a method of making a dispersion composition as described herein, the method comprising: [0060] a) adjusting a polymer emulsion or dispersion with a base to a desired pH; [0061] b) adding one or more waxes to the polymer emulsion or dispersion under agitation; [0062] c) adding one or more functional additives to the mixture under agitation; and [0063] d) adding one or more preservatives under agitation. [0064] In a preferred embodiment of this aspect, no heating, cooling, or homogenization is applied. [0065] In another aspect, the present invention provides a method of making an eye composition, comprising: [0066] a) mixing one or more diluents with one or more preservatives to form a mixture; [0067] b) adding a dispersion composition according to any embodiments described herein and mixing till uniform; and [0068] c) filling with mixture obtained in b) with one or more filler materials. [0069] In one embodiment of this aspect, the diluents are selected from water, oil, silicone, and hydrocarbon fluids. [0070] In another embodiment of this aspect, the method further includes adding a thickener to stabilize the final product. [0071] In another embodiment of this aspect, the method further includes adding one or more additional ingredients to make performance claims. [0072] In a preferred embodiment of this aspect, no heating, cooling or homogenization is applied. [0073] In another embodiment, the present invention provides a rub-resistant mascara incorporating a dispersion composition according to any embodiment described herein. [0074] In another embodiment, the present invention provides a water-resistant mascara incorporating the dispersion composition according to any embodiment described herein. [0075] In another embodiment, the present invention provides a mascara incorporating the dispersion composition of according to any embodiment described herein, which is both water resistant and rub resistant. In another embodiment, the water and rub-resistant mascara has a dark color as measured by an L value in the range of 9 to 11. [0076] The present invention is additionally described by the way of the following illustrative, non-limiting examples that provides a better understanding of the present invention and of its advantage. EXAMPLES Example 1 Lengthening Mascara Concentrate [Cold Process] [0077] [0000] % W/W Part A Triethanolamine 99% 0.29 Daitosol 5000SJ 24.03 (Acrylates/Ethylhexyl Acrylate Copolymer, Water) Deionized Water 2.86 Dow Corning ® Antifoam C 1.00 Part B Microcare ® 310 (polyethylene, Carnauba wax) 4.75 Micropoly ® 250S (polyethylene,) 9.00 Part C SUN PMMA-S (PMMA from Sunjin) 18.25 NFCB-10D-2T (Nylon-12 fiber) 1.75 Part D W60BBNFAP-O (from Kobo) 34.60 (60% Black iron oxide dispersion in water) Part E Xanthan Gum 0.35 Optiphen ® (Caprylyl Glycol, Phenoxyethanol) 0.65 Symdiol ® 68 (1,2-Hexanediol, Caprylyl Glycol) 0.60 Part F Ethyl Alcohol SDA 40B - 190 Proof 1.72 Sorbic Acid NF 0.15 Total: 100.00 Procedure [0000] 1. For Part A combine the TEA and Daitosol. Mix together gently. Adjust the pH level to 8.00-8.20 using TEA. Add the Water and Antifoam with very low stirring for 5 minutes. [0079] 2. Add the waxes in Phase B to Part A. Disperse with the Cowles Mixer at low speed for 20 minutes. 3. Add the NFCB-10D-2T in Part C and stir with the Cowles Mixer at low speed for 20 minutes. [0081] The volume of the batch will rise due to the nylon. 4. Add the PMMA and stir with the Cowles Mixer at low speed for 20 minutes. 5. Add PART D pigment slurry to ABC. The viscosity will become thinner. Disperse with the Cowles Mixer at low speed for 20 minutes. 6. Slurry together the ingredients of PART F and add to Phase ABCD. Disperse very slowly with the Cowles Mixer at low speed for 20 minutes. Continue stirring until the air is reduced to a minimum. 7. Add the sorbic acid to the ethanol in PART E and stir together for 5 minutes. Add to the batch ABCDE. Disperse for 15 minutes. Example 2 Thickening Mascara Concentrate [Cold Process] [0086] [0000] % W/W Part A Triethanolamine 99% 0.29 Daitosol 5000SJ 24.03 (Acrylates/Ethylhexyl Acrylate Copolymer, Water) Deionized Water 0.21 Dow Corning ® Antifoam C 1.00 Part B Microcare ® 310 (polyethylene, Carnauba wax) 4.75 Micropoly ® 250S (polyethylene) 9.00 Part C SUN PMMA-S (PMMA, Sunjin) 18.25 MSS-500/N (Silica, Kobo) 5.00 Part D W60BBNFAP-O (from Kobo) 34.00 (Black iron oxide dispersion in water) Part E Xanthan Gum 0.35 Optiphen ® (Caprylyl Glycol, Phenoxyethanol) 0.65 Symdiol ® 68 (1,2-Hexanediol, Caprylyl Glycol) 0.60 Part F Ethyl Alcohol SDA 40B - 190 Proof 1.72 Sorbic Acid NF 0.15 Total: 100.00 Procedure [0000] 1. For Part A combine the TEA and Daitosol. Mix together gently. Add the Water and Antifoam with very low stirring for 5 minutes. Adjust the pH level to 8.00-8.20 using TEA. 2. Add the waxes in Phase B to Part A. Disperse with the Cowles Mixer at low speed for 20 minutes. 3. Add the Silica beads MSS-500/N in Part C and stir with the Cowles Mixer at low speed for 20 minutes. 4. Add the PMMA and stir with the Cowles Mixer at low speed for 20 minutes. 5. Add PART D pigment slurry to ABC. The viscosity will become thinner. Disperse with the Cowles Mixer at low speed for 20 minutes. 6. Slurry together the ingredients of PART E and add to Phase ABCD. Disperse very slowly with the Cowles Mixer at low speed for 20 minutes. Continue stirring until the air is reduced to a minimum. 7. Add the sorbic acid to the ethanol in PART F and stir together for 5 minutes. Add to the batch ABCDE. Disperse for 15 minutes. Example 3 Eyeliner Concentrate [Cold Process] [0094] [0000] % W/W: Part A Triethanolamine 99% 0.28 Daitosol 5000SJ 30.24 (Acrylates/Ethylhexyl Acrylate Copolymer, Water) Deionized Water 1.73 Dow Coming ® Antifoam C 1.00 Part B Microcare ® 310 (polyethylene, Carnauba wax) 2.50 Micropoly ® 250S (polyethylene) 5.00 Part C SUN PMMA-S (PMMA, Sunjin) 18.25 Part D W60BBNFAP-O (from Kobo) 28.13 (60% Black iron oxide dispersion in water) WBG20CB (from Kobo) 9.60 (20% Black No. 2 dispersion in water) Part E Xanthan Gum 0.15 Optiphen ® (Caprylyl Glycol, Phenoxyethanol) 0.65 Symdiol ® 68 (1,2-Hexanediol, Caprylyl Glycol) 0.60 Part F Ethyl Alcohol SDA 40B - 190 Proof 1.72 Sorbic Acid NF 0.15 Total: 100.00 Procedure [0000] 1. For Part A combine the TEA and Daitosol. Mix together gently. Add the Water and Antifoam with very low stirring for 5 minutes. Adjust the pH level to 8.00-8.20 using TEA. 2. Add the waxes in Phase B to Part A. Disperse with the Cowles Mixer at low speed for 20 minutes. 3. Add the PMMA and stir with the Cowles Mixer at low speed for 20 minutes. 4. Add PART D both pigment slurries to ABC. The viscosity will become thinner. Disperse with the Cowles Mixer at low speed for 20 minutes. 5. Slurry together the ingredients of PART F and add to Phase ABCD. Disperse very slowly with the Cowles Mixer at low speed for 20 minutes. Continue stirring until the air is reduced to a minimum. 6. Add the sorbic acid to the ethanol in PART E and stir together for 5 minutes. Add to the batch ABCDE. Disperse for 15 minutes. Example 4 Lengthening Mascara Concentrate (Low-Heat Process) [0101] [0000] % W/W PART A Triethanolamine 99% 0.29 Daitosol 5000SJ 24.03 Deionized Water 2.86 Antifoam C 1.00 PART B Cetearyl Alcohol and Ceteareth-20 8.85 Micropoly ® 250S (polyethylene) 5.00 PART C NFCB-10D-2T 1.75 PART D W60BBNFAP-O (Kobo Products) 34.50 PART E SUN PMMA-S 18.25 PART F Xanthan Gum 0.35 Optiphen 0.65 Symdiol 68 0.60 PART G Ethyl Alcohol SDA 40B - 190 Proof 1.72 Sorbic Acid NF 0.15 *TOTALS: 100.00 Procedure [0000] 1. For Part A combine the TEA and Daitosol. Mix together gently. Add the Water and Antifoam with very low stirring for 5 minutes. Adjust the pH level to 8.00-8.20 using TEA. Heat to 55° C. with stirring. 2. Add the NFCB-10D-2T in Part C to A. Disperse with the Cowles Mixer for 20 minutes 3. Add the pigment slurry Part D to AC and disperse with the Cowles mixer for 20 minutes. 4. Heat and slowly stir the Cetearyl Alcohol to 55° C. Add the Cetearyl Alcohol in Phase B to Part AC when both phases reach 55° C. Hold temperature for 10 minutes while mixing. 5. Begin slow cooling and add the PMMA and Micropoly 250S at 50° C. Continue dispersing with the Cowles mixer. 6. At 45° C. slurry together the ingredients of Part F and add to ABCDE. 7. Add the sorbic acid to the ethanol in PART G and stir together for 5 minutes. Add to the batch at 37° C. 8. Continue cooling and dispersing with the Cowles mixer while cooling to 27°-30° C. and fill. Example 5 Thickening Mascara Concentrate (Low Heat Process) [0110] [0000] % W/W PART A Triethanolamine 99% 0.29 Daitosol 5000SJ 24.03 Antifoam C 1.00 PART B Cetearyl Alcohol and Ceteareth-20 8.85 Micropoly ® 250S (polyethylene) 5.00 PART C MSS-500/N 5.00 PART D W60BBNFAP-O (Kobo Products) 34.05 PART E SUN PMMA-S 18.25 PART F Xanthan Gum 0.35 Optiphen 0.65 Symdiol 68 0.60 PART G Ethyl Alcohol SDA 40B - 190 Proof 1.78 Sorbic Acid NF 0.15 *TOTALS: 100.00 Procedure [0000] 1. For Part A combine the TEA and Daitosol. Mix together gently. Add the Water and Antifoam with very low stirring for 5 minutes. Adjust the pH level to 8.00-8.20 using TEA. Heat to 55° C. with stirring. 2. Add the NFCB-10D-2T in Part C to A. Disperse with the Cowles Mixer for 20 minutes 3. Add the pigment slurry Part D to AC and disperse with the Cowles mixer for 20 minutes. 4. Heat and slowly stir the cetearyl alcohol to 55° C. Add the cetearyl alcohol in Phase B to Part AC when both phases reach 55° C. Hold temperature for 10 minutes while mixing. 5. Begin slow cooling and add the PMMA and Micropoly 250S at 50° C. Continue dispersing with the Cowles mixer. 6. At 45° C. slurry together the ingredients of Part F and add to ABCDE. 7. Add the sorbic acid to the ethanol in PART G and stir together for 5 minutes. Add to the batch at 37° C. 8. Continue cooling and dispersing with the Cowles mixer while cooling to 27°-30° C. and fill. Example 6 Lash Primer or Topcoat Concentrate [Cold Process] [0119] [0000] % W/W Part A Triethanolamine 99% 0.29 Daitosol 5000SJ 24.03 (Acrylates/Ethylhexyl Acrylate Copolymer, Water) Deionized Water 13.81 Dow Corning ® Antifoam C 1.00 Part B Microcare ® 310 (polyethylene, Carnauba wax) 4.75 Micropoly ® 250S (polyethylene) 9.00 Part C SUN PMMA-S (PMMA, Sunjin) 23.65 MSS-500/N (Silica, Kobo) 5.00 Part D Sericite GMS-4C 15.00 Part E Xanthan Gum 0.35 Optiphen ® (Caprylyl Glycol, Phenoxyethanol) 0.65 Symdiol ® 68 (1,2-Hexanediol, Caprylyl Glycol) 0.60 Part F Ethyl Alcohol SDA 40B - 190 Proof 1.72 Sorbic Acid NF 0.15 Total: 100.00 Procedure [0000] 1. For Part A combine the TEA and Daitosol. Mix together gently. Add the Water and Antifoam with very low stirring for 5 minutes. Adjust the pH level to 8.00-8.20 using TEA. 2. Add the waxes in Phase B to Part A. Disperse with the Cowles Mixer at low speed for 20 minutes. 3. Add the Silica beads MSS-500/N in Part C and stir with the Cowles Mixer at low speed for 20 minutes. 4. Add the PMMA and stir with the Cowles Mixer at low speed for 20 minutes. 5. Add PART D Sericite to ABC. The viscosity will become thicker. Disperse with the Cowles Mixer at low speed for 20 minutes. 6. Slurry together the ingredients of PART E and add to Phase ABCD. Disperse very slowly with the Cowles Mixer at low speed for 20 minutes. Continue stirring until the air is reduced to a minimum. 7. Add the sorbic acid to the ethanol in PART E and stir together for 5 minutes. Add to the batch ABCDE. Disperse for 15 minutes. [0127] The solids of the concentrates were tested by drying at 105 C for 2 h and the value was in a range of 70-75%. Viscosity was tested using a Brookfield viscosity RVT at 2.5 rpm and the results were a range of 150,000-350,000 cps. They are stable at room temperature and 45 C in 2 months stability test. [0128] The concentrates can now be use to formulate a variety of the final mascara or eyeliner composition. The process is simple and easy. It requires only mixing at room temperature using a Cowles Mixer or the equivalent and a tank. No heating or homogenization is needed. The following are illustrative examples. Example 7 Sepigel® 305 Mascara Formula from the Concentrate [0129] [0000] % W/W Part A Sepigel ® 305 (from Seppic) 2.50 (Polyacrylamide, C13-14 Isoparaffin, Laureth-7) Deionized Water 47.00 Optiphen ® Plus 0.50 Part B Lash Thickening Concentrate (Example 2) 50.00 Procedure: [0000] 1. Part A, begin mixing the deionized water in at room temperature then add the Sepigel 305 and stir for 20 minutes. Add the Optiphen Plus and stir for an additional 5 minutes. 2. Add the Lash Thickening Concentrate to the gel and stir for 20 minutes using a Cowles dissolver. 3. Fill. Example 8 Natrosol® HHR CS Mascara formula from the concentrate [0133] [0000] % W/W Part A Natrosol ® HHR CS (From Aqualon) 1.50 (hydroxyethylcellulose) Deionized Water 48.00 Optiphen Plus 0.50 Part B Lash Lengthening Concentrate (Example 1) 50.00 Procedure: [0000] 1. Part A, begin mixing the deionized water at room temperature then add the Natrosol and stir for 45 minutes. Add the Optiphen Plus and stir for an additional 5 minutes. [0135] 2. Add the Lash Lengthening Concentrate to the gel and stir for 20 minutes using a Cowles dissolver. 3. Fill. Example 9 Keltrol® CG Mascara Formula from the Concentrate [0137] [0000] % W/W Part A Keltrol ® CG (Xanthan Gum from CP Kelco) 1.00 Deionized Water 48.50 Optiphen ® Plus 0.50 Part B Lash Thickening Concentrate (Example 1) 50.00 Procedure: [0000] 1. Part A, begin mixing the deionized water at room temperature then add the Keltrol and stir for 45 minutes. Add the Optiphen Plus and stir for an additional 5 minutes. 2. Add the Lash Thickening Concentrate to the gel and stir for 20 minutes using a Cowles dissolver. 3. Fill. Example 10 Keltrol® CG Eyeliner Formula from the Concentrate [0141] [0000] % W/W: Part A Keltrol ® CG (from CP Kelco) 0.50 Deionized Water 49.00 Optiphen ® Plus 0.50 Part B Eyeliner Concentrate (Example 3) 50.00 Procedure: [0000] 1. Part A, begin mixing the deionized water at room temperature then add the Keltrol and stir for 45 minutes. Add the Optiphen Plus and stir for an additional 5 minutes. 2. Add the Eyeliner Concentrate to the gel and stir for 20 minutes using a Cowles dissolver. 3. Fill. Example 11 Silicone Eyeliner Formula from the Concentrate [0145] [0000] % W/W: Part A Dow Corning ® 5225C Formulation aid 20.00 Cyclopentasiloxane 29.50 Optiphen ® Plus 0.50 Part B Eyeliner Concentrate (Example 3) 50.00 Procedure: [0000] 1. Part A, begin mixing the two silicones in phase A at room temperature stirring for 10-15 minutes. Add the Optiphen Plus and stir for an additional 5 minutes. 2. Add the Eyeliner Concentrate to the silicone phase and stir for 20 minutes using a Cowles dissolver. 3. Fill. Example 12 Silicone Mascara Formula from the Concentrate [0149] [0000] % W/W: Part A Dow Corning ® 5225C Formulation aid 20.00 Cyclopentasiloxane 29.50 Optiphen ® Plus 0.50 Part B Lash Thickening Concentrate (example 1) 50.00 Procedure: [0000] 1. Part A, begin mixing the two silicones in phase A at room temperature stirring for 10-15 minutes. Add the Optiphen Plus and stir for an additional 5 minutes. 2. Add the Lash Thickening Concentrate to the silicone phase and stir for 20 minutes using a Cowles dissolver. 3. Fill. [0153] cl Example 13 Sepigel® 305 Mascara Formula from the Concentrate [0154] [0000] % W/W: Part A Sepigel ® 305 (from Seppic) 2.50 Deionized Water 44.50 KTZ ® Roussillon 2.50 Optiphen ® Plus 0.50 Part B Lash Thickening Concentrate (Example 5) 50.00 Procedure: [0000] 1. Part A, begin mixing the deionized water in at room temperature then add the Sepigel 305 and stir for 20 minutes. Add the Optiphen Plus and stir for an additional 5 minutes. 2. Add the Lash Thickening Concentrate to the gel and stir for 20 minutes using a Cowles dissolver. 3. Fill. Example 14 Natrosol® HHR CS Mascara Formula from the Concentrate [0158] [0000] % W/W: Part A Natrosol ® HHR CS (From Aqualon) 1.50 Deionized Water 45.50 KTZ Celandon Blue 2.50 Optiphen Plus 0.50 Part B Lash Lengthening Concentrate (Example 4) 50.00 Procedure: [0000] 1. Part A, begin mixing the deionized water at room temperature then add the Natrosol and stir for 45 minutes. Add the Optiphen Plus and stir for an additional 5 minutes. 2. Add the Lash Lengthening Concentrate to the gel and stir for 20 minutes using a Cowles dissolver. 3. Fill. Example 15 Natrosol® HHR CS Lash Primer or Topcoat Formula from the Concentrate [0162] [0000] % W/W: Part A Natrosol ® HHR CS (From Aqualon) 1.50 Deionized Water 48.00 Optiphen Plus 0.50 Part B Lash Primer or Topcoat Concentrate (Example 6) 50.00 Procedure: [0000] 1. Part A, begin mixing the deionized water at room temperature then add the Natrosol and stir for 45 minutes. Add the Optiphen Plus and stir for an additional 5 minutes. 2. Add the Lash Lengthening Concentrate to the gel and stir for 20 minutes using a Cowles dissolver. 3. Fill. Comparison Studies [0166] Leading marketed mascaras, 9 products from 8 brands, were purchased from Wal-Mart displays and used for the following tests: Rub Resistant Test [0167] Rub resistance testing demonstrates the strength, adhesion and flexibility of the films incorporating the concentrate. Samples were weighed, applied to transpore tape to make films that were allowed to dry at 24 C for 24 hours. These films were abraded at a constant pressure and weight of 500 grams. The remaining film was digitized and transferred to image analysis software for results. A low score in the testing indicates by a low transfer during wear, also known as smudge-resistance (Table 1). Water Resistance Test [0168] Water-resistance testing demonstrates the hydrophobic nature of the films incorporating the concentrate. A fixed amount of samples were weighed and applied in a Petri dish and allowed to dry at 24 C for 24 hours. The resultant films were then exposed to a circulating water bath for 4 hours. The remaining film was dried and weighed to determine its water-resistance. A high score in the testing indicating a high water-resistance during wear (Table 1). Color Analysis [0169] For mascaras and eyeliners it is important that they have a deep, rich color or intensity. One gram of sample was applied and spread to a PMMA plate (3 inches in diameter) and allowed to dry for 24 hours. The color was analyzed by a Datacolor colorimeter using CIE Lab system. A lower L value indicates a darker color (Table 1). [0000] TABLE 1 Test results Water Rub- Commercial Resistance Resistant Darkness mascara Name (%) (%) (L) 1 Maybelline Illegal 82.79 5.53 15.95 Length 2 L'Oreal Voluminous 90.35 2.17 15.2 Naturale 3 Maybelline Great Lash 19.63 7.70 14.68 4 Revlon Photoready 68.68 3.84 17.42 5 Wet N Wild 79.23 8.14 16.85 Megaprotein 6 NYC City Curls 0.00 7.56 15.38 7 Rimmel Volume 80.16 3.22 14.46 Accelerator 8 Revlon Grow Luscious 10.01 2.96 19.14 9 Neutrogena Healthy 16.06 9.94 13.63 Volume Example 7 95.35 0.06 9.72 Example 8 96.80 0.04 10.91 Example 9 96.62 0.07 11.00 Example 12 96.01 1.57 10.97 [0170] The foregoing examples and description of the preferred embodiments should be taken as illustrating, rather than as limiting the present invention as defined by the claims. As will be readily appreciated, numerous variations and combinations of the features set forth above can be utilized without departing from the present invention as set forth in the claims. All such variations are intended to be included within the scope of the following claims.

This application discloses an aqueous dispersion of waxes, polymers, pigments and other functional additives, which can be used as a concentrate of an eye make-up composition. The dispersion contains about 70% solids and can be diluted at room temperature and adjusted with additional ingredients if desired, which enables commercial cosmetic manufacturers to develop and manufacture new formulations with the minimal effort and cost.

RELATED U.S. APPLICATION DATA [0001] This application is a division of U.S. patent application Ser. No. 10/849,809, filed on May 21, 2004, which continues-in-part from U.S. patent application Ser. No. 10/297,384, filed 6 Dec. 2002. FIELD OF THE INVENTION [0002] The present invention relates generally to the field of packs/packaging, and in particular dispensing packs/packaging. In particular the present invention relates to a dispensing nozzle assembly with a re-useable break-off (or break-away) cap. The nozzle assembly may be attachable to a container or integrally formed therewith. The nozzle may thus be closed with the cap after the cap has been broken off. The nozzle may be attachable to or integrally formed with a container and the containers contents are thus protectable by the re-useable cap. In one aspect of the invention, a dispensing nozzle incorporating an applicator, such as a flow through brush applicator, is provided. BRIEF DESCRIPTION OF RELATED TECHNOLOGY [0003] It is desired to provide inexpensive re-useable dispensing packs which offer the user the opportunity to partially dispense the contents of a container and store the remainder for later use. The user can dispense as much of the contents as required and then re-close (or reseal) the pack to store the contents for a future use. Re-sealing the pack is important particularly for materials which are sensitive to their environment for example products which are air, moisture, light sensitive etc. [0004] Many re-closeable packs are known. In general these may be complex to manufacture and require removable caps etc. which allow the container to be re-sealed after a use. On the other hand it is known to provide single use or “one shot” disposable pack which once opened cannot be subsequently closed. This form of pack is usually a tear- or break-open pack. The advantage of a one shot pack is its relatively inexpensive manufacture as compared to re-closeable or re-sealable packs. The disadvantage of such containers is of course that the contents are intended to be used all at once. If not all the product is used at one time, there is a difficulty in storing the pack as it is not closed and the contents may spill. The life of the remaining product may also be compromised particularly as stated above where the product is sensitive to environmental factors. [0005] It is also possible to provide low cost tubes, for instance a tube constructed of aluminium or other such metal or plastics materials. Such tubes are often provided with screw-on, snap-on, or otherwise engageable nozzles. The nozzle is usually provided to help accurate dispensing of the contents of the tube. These nozzles are often provided with separate screw-on caps to close the dispensing nozzle to protect the product. The nozzle and the cap are separately provided and the cap is screwed onto the nozzle. In order to use the dispensing nozzle it is firstly screwed onto the tube. A dispenser with dispensing means for dispensing the contents of the tubes is known for example from WO 00/00405. The device is provided with a nozzle which screws onto the tube and a cap which screws onto the nozzle. The device of WO 00/00405 may be used with a nozzle assembly or container of the present invention. Alternatively a container with an integrally formed nozzle may be provided. Containers with integrally formed dispensing nozzles are also often deformable (squeezable). [0006] There exists a requirement for a low cost multi-use pack. [0007] A further problem in providing a reusable container or nozzle assembly with a break-off cap is difficulty in re-closing the container/nozzle to provide a reliable seal to protect the contents of the container. It is difficult to provide low cost containers/nozzles which close after use to provide a reliable seal. Creating a reliable seal necessitates accurate mating of the surfaces forming the seal. This in turn requires careful manufacture with precise engineering of the product which may be reflected in increased cost in production. Generally components which mate to provide a seal are manufactured separately and with great precision so that the subsequent making of the components provides the desired seal. [0008] Difficulty of re-closure is especially acute with break-off caps. Break-off caps are frangibly connected to the container which they close. Breaking the frangible connection between the break-off part (usually the cap) and the container may leave remnants of the frangible connection on the break-off part or on the container. These remnants may interfere with subsequent re-fitting of the break-off part to the container thus making proper re-closure of the container difficult, with possible ensuing detriment to the useable life of the product within the container. As stated above there are certain types of products which particularly need protection from the general environment. Of particular concern in the present case are curable products, in particular adhesives. [0009] EP 0 326 529 describes a strip of phials. The document is concerned with the problem of handling of relatively small phials, and proposes a strip or web of phials which are more easily handled mechanically. Each phial is a small squeezable container with an integrally moulded nozzle and cap on the container. The cap is a break-off cap and the containers are intended to be single use “one shot” containers. [0010] Henkel Loctite (Ireland) Limited manufactures and sells a product under the trademark Indermil® which is approved for sale as a tissue adhesive for biomedical uses. The product is presented for sale in individual phials similar in construction to the phials disclosed in EP 0 326 529 discussed above. The phial has a hollow container body for receiving and holding product placed in the container. The hollow container body has an outlet nozzle, through which the product is dispensable. The outlet nozzle has a first intake end which projects from the container body and is integrally formed therewith. The nozzle has a second dispensing end with a dispensing opening formed in the dispensing end and a mouth formed on the nozzle about the dispensing opening. The nozzle of the device has a nozzle body with a conduit defined therein and bounded by an internal surface of the nozzle body, the conduit in communication with the container body and the dispensing opening. The phial has a break-off cap comprising a cap body for closing the dispensing end of the outlet nozzle, the break-off cap having a first position wherein the cap body is integrally formed with the outlet nozzle to close the outlet opening of the outlet nozzle and is connected thereto by at least one frangible connection, and a second position wherein the frangible connection is broken allowing removal of the cap and thus opening the outlet opening thereby allowing product to be dispensed from the container. The cap once removed may be inverted and repositioned on the container by push-fit (frictional) engagement of the cap and the nozzle. It is desired to provide an alternative nozzle assembly for use with a container which can be used to store materials. In order to improve the useful life of products stored in containers it may be desirable to provide an outer (protective) packaging which may help improve storage stability, particularly one that is convenient for point of sale display. [0011] The aforementioned dispensing packs dispense a portion of product directly through the nozzle. For certain uses, it is desirable not only to dispense product but to control the application of the dispensed product to an intended surface. For example, in one such instance, it may be necessary to spread the dispensed product thinly across a surface. [0012] It is desirable to provide inexpensive reusable dispensing packs incorporating an applicator. SUMMARY OF THE INVENTION [0013] A first aspect of the present invention provides a nozzle assembly comprising: [0014] a) an outlet nozzle for dispensing product, having a first intake end for taking up product from a container and a second dispensing end with a dispensing opening formed in the dispensing end and a mouth formed on the nozzle about the dispensing opening, the nozzle comprising a nozzle body with a conduit defined therein and bounded by an internal surface of the nozzle body, the conduit for communication between the intake end of the nozzle and the dispensing opening; and [0015] b) a break-off cap comprising a cap body for closing the dispensing end of the outlet nozzle, the break-off cap having a first position wherein the cap body is integrally formed with the outlet nozzle to close the dispensing opening of the outlet nozzle and is connected thereto by at least one frangible connection, and a second position wherein the frangible connection is broken allowing removal of the cap and thus opening the dispensing opening thereby allowing product to be dispensed through the outlet nozzle; [0016] the nozzle assembly having an internal annular crotch, which narrows in a radially outward direction, formed between the nozzle and the cap body about the dispensing opening, the crotch providing a weakened junction between the cap and the nozzle allowing the cap to be broken off from the nozzle thus breaking the frangible connection. [0017] In a second aspect the present invention provides a nozzle assembly comprising: [0018] a) an outlet nozzle for dispensing product having a first intake end for taking up product from the container and a second dispensing end with a dispensing opening formed in the dispensing end and a mouth formed on the nozzle about the dispensing opening, the nozzle comprising a nozzle body with a conduit formed therein defined by an internal surface of the nozzle body, the conduit for communication between the intake end and the dispensing opening; and [0019] b) a break-off cap comprising a cap body for closing the dispensing end of the outlet nozzle, the break-off cap having a first position wherein the cap body is integrally formed with the outlet nozzle to close the dispensing opening of the outlet nozzle and is connected thereto by at least one frangible connection, and a second position wherein the frangible connection is broken allowing removal of the cap and thus opening the dispensing opening thereby allowing product to be dispensed through the outlet nozzle; [0020] the cap body and the outlet nozzle having interengaging formations for subsequently securing the break-off cap to the nozzle body to close the outlet opening. [0021] In a third aspect of the present invention the first and second aspects of the invention may be combined in a single nozzle assembly. This combined nozzle assembly is particularly useful to provide re-useable containers. The nozzle assembly combining the features of the first and second aspects allows for ease of removal of the cap from the nozzle and also subsequent re-fitting of the cap to the nozzle. [0022] It is particularly desirable that the nozzle (and thus the nozzle assembly) forms an integral part of the container, though as explained above the nozzle assembly may be adapted to engage on an existing container, for example by snap-fitting or screw-threading. [0023] The (internal) annular crotch allows for ease of removal of the cap as the apex of the crotch runs toward (and preferably meets) the frangible connection so that resistance to breaking off is not so great as it might otherwise be. The annular crotch may thus be considered inside, or interior to the frangible connection. There is less of a tendency for the remnants of the frangible connection to remain on the nozzle, thus facilitating ease of subsequent re-closure of the nozzle. There is thus provided a weakened junction (or a circumferential line of weakness) between the cap and the nozzle. [0024] The crotch may be generally v-shaped being defined on one side by a surface of the cap body and on the other by a surface of the nozzle. The surfaces defining the cap may diverge in a radially inward direction. In the radially outward direction the surfaces of the crotch may converge toward the frangible connection to (a point of convergence to) form the apex of the v-shape. At the apex the nozzle and the cap are frangibly connected. [0025] The surface on the nozzle defining one side of the crotch may run from the internal surface of the nozzle, or from a position proximate to the internal surface of the nozzle to the mouth of the nozzle. The annular crotch is thus internal to the nozzle/cap arrangement. [0026] In one particularly simple though desired construction one side of the internal annular crotch is provided, at least in part, by a ramped surface running from the internal surface of the nozzle defining the conduit to the mouth of the nozzle. The ramped surface is desirably annular. In one arrangement the annular ramped surface is of a generally frusto-conical shape (narrowing in diameter downwardly) for example gradually decreasing in diameter from the mouth of the nozzle to the surface defining the conduit. This embodiment allows for ease of re-closing the container with a reliable seal as will be described below. [0027] To further ensure ease of removal of the cap from the nozzle the nozzle assembly is desirably provided with an external annular crotch, which narrows in a radially inward direction, formed between the nozzle and the cap body about the dispensing opening, the external crotch providing a weakened junction (exterior to the frangible connection). [0028] As with the (internal) annular crotch described above, the external crotch may be generally v-shaped being defined on one side by a surface of the cap body and on the other by a surface of the nozzle. The surfaces defining the cap may diverge in a radially outward direction. In the radially inward direction the surfaces of the crotch may converge toward the frangible connection to form the apex of the v-shape. At the apex the nozzle and the cap are frangibly connected. [0029] The surface on the nozzle defining one side of the external crotch may run from an external (side) surface of the nozzle, to a position on the nozzle proximate or at the mouth of the nozzle. [0030] Typically the frangible connection is formed by plastics material during moulding of the container of the invention from plastics material. [0031] The provision of the internal annular crotch allows for particular clean break-off of the cap. Clean surfaces (surfaces without remnants of the frangible connection) are left about the nozzle mouth so that subsequent re-closure of the nozzle (and thus the container) is facilitated. Good mating of the cap and nozzle surfaces help to protect product within the container from environmental influences. [0032] A container according to the second aspect (or third aspect) of the present invention is thus provided with a re-closeable cap which is easily re-fitted to the nozzle (container) to provide a reliable seal. The container and the nozzle assembly can be moulded as a single piece for example from plastics material, thus making an integrally formed container which is relatively low cost to produce. [0033] A container having a nozzle assembly according to any aspect of the present invention is desirably a hand-held phial. The phial may be constructed of deformable plastics so that it may be squeezable (by manual pressure and in particular finger pressure) to express product. Optionally the phial may be constructed of clear or translucent plastics. The plastics material can be sufficiently translucent to allow the level of product within the container to be determined by external viewing (through the sides of the container). [0034] The interengaging formations may for example be screw-threads. Alternatively the interengaging formations may be snap-fit formations. In one desirable arrangement the interengaging formations are snap-fit formations that are disengageable from the interengaged position by relative rotation of the cap and the nozzle. Where the nozzle is on, or is integrally formed with a container, this will also occur where the cap and the container are rotated relative to each other. It is desirable that the interengaging formations snap-fit to hold the cap to the nozzle and/or container, and yet, allow twisting off of, the cap, from the nozzle and/or container. This arrangement allows for particular ease of the replacement and removal of the cap, on or from the nozzle (container). [0035] The break-off cap is desirably held in an inverted position on the outlet nozzle before it is broken off. In this arrangement an outer surface of the cap closes the dispensing opening on the nozzle (which may in turn be connected to an outlet opening on the tube). This is an especially simple construction. Suitably the outer surface of the cap closing the dispensing opening is an internal wall of a recess or housing formed on the cap the housing mating with the mouth of the nozzle. This arrangement ensures unwanted plastics material produced during moulding does not inadvertently interfere with the dispensing opening. [0036] The break-off cap is desirably reversible so that when broken off, the cap may be inverted for replacement on to the nozzle (container). In this embodiment it is desirable that the cap body comprises a housing for receiving the outlet nozzle, the formations for interengaging with the reciprocal interengaging formations on the nozzle or on the container being formed on the housing desirably internally. In this embodiment an inner surface of the cap (a surface within the housing) closes the outlet opening. This embodiment is particularly advantageous as if remnants of the frangible connection remain on the cap, after the cap has been broken off, then the remnants will be on the exterior of the cap (in the closed position of the cap). The remnants cannot then interfere with closure. This arrangement ensures also that a proper seal is formed between the cap and the nozzle so that when the filling process is completed though the open base end of the container, and the base of the container sealed, the entire container is sealed by an integrally formed body. No concerns about proper securing of the cap on the nozzle/container then arise. [0037] The interengaging formations may be formed by one or more projections and one or more corresponding recesses or grooves with which the projections engage. The projections and the grooves/recesses may be located respectively on the nozzle and on the cap or vice versa. This arrangement may provide for snap-fit engagement of the cap on the nozzle/container. [0038] Desirably the cap has a discharge opening engaging portion for closing the dispensing opening. This may be a projecting portion on the underside of the cap which at least partially projects into the dispensing opening of the nozzle. This is a desirable construction as the projecting portion may help to provide a reliable seal between the cap and the nozzle. Where the internal annular crotch is provided, at least in part with a ramped surface, the projecting portion is desirably shaped to mate. When the ramped surface is of a generally (inverted) frusto-conical shape it is desired that the projecting portion is shaped to mate, for example of a conical or frusto-conical shape. This arrangement allows for ease of reclosure of the cap. In one highly desired embodiment the projecting portion is conical in shape. [0039] In one particularly advantageous construction the nozzle is oblong in cross section and the cap is correspondingly shaped (for mating of the nozzle and the cap) so that relative rotation of the cap and the nozzle/container causes deformation of the cap and allows for its removal. The cap and nozzle can be said to be irregularly shaped, i.e., their shapes do not allow for relative rotation without deformation of at least the cap taking place. Where snap-coupling means are provided deformation of the cap desirably disengages the snap-coupling means allowing for removal of the cap. One way to achieve this function is to provide a nozzle which is oblong in cross-section and which has a four sided configuration so that in cross-section it has two opposing substantially flat sides and two opposing curved ends. The cap may taper (narrow) towards its top end to correspond to the shape of the nozzle. When a cap is provided with reciprocal (for example an over-fitting) shape relative rotation of the nozzle and the cap will cause deformation of the cap and/or the nozzle/container. It is desired that for the most part it is the cap which deforms on relative rotation. In this construction the snap-fit engagement means may be provided on the flat sides of the nozzle (and on the corresponding sides of the cap) so that the cap can be relatively easily removed from the container by relative rotation of the cap and the container. [0040] Desirably the nozzle and the cap have co-operating guiding surfaces which guide the cap toward a desired orientation relative to the nozzle. In particular it is desired for aesthetic, handling, packaging and other purposes that the cap and the nozzle/container have a certain alignment. For instance where the cap and the container are flat in shape it may be desired to align the cap with the container so that the cap remains in line with the container body. This can also ensure that the cap is correctly seated on the nozzle. In one desired construction the guiding surfaces will align the cap on the nozzle if the cap and nozzle are within about 45° of the desired alignment. The guiding surface may be a seat and a corresponding seat-engaging portion. The seat may be a recess on the nozzle into which a projection (on the cap) fits. That part of the nozzle or the cap forming the seat may also provide one or more stops to prevent incorrect alignment of the cap and the nozzle/container. This arrangement is particularly desirable, where otherwise, the cap and the nozzle could be forced together in an undesired orientation. [0041] The invention provides in a fourth aspect a series of tear-off blisters frangibly attached each to the next, each blister comprising a blister tray, and a flexible peel-off cover for the blister tray, the peel-off cover and the blister tray being attached by re-sealable means, for example an adhesive, which allows reclosing of the blister. This is one particularly advantageous embodiment which is especially useful to help prolong the life of products which may otherwise deteriorate. This applies also to products which may be stored in a container of the present invention, and which may have their useable life extended by storage of the container within an exterior protective pack such as a blister pack. It is desirable that a peel-open tab is provided on each blister to facilitate peeling open of the pack. The tabs may be on the peel-off corner or the tray. [0042] In a fifth aspect the invention provides a series of tear-off pouches formed by sealing two layers of flexible material to each other about discrete areas, the pouches frangibly attached each to the next, each pouch being provided with a tear-open notch to facilitate tearing open of the material forming the pouch. The tear-off notch allows the pack to ripped open more easily so a user can access the contents. [0043] The invention in a sixth aspect also relates to a combination package, the combination package comprising a container of the present invention as described above and an outer pack, the outer pack being a blister- or pouch-type pack. Suitably the blister- or pouch-type pack is in the form of a strip or array pack. This is one particularly convenient method of packaging a container according to the present invention. [0044] The invention provides in a seventh aspect a dispensing nozzle assembly comprising: [0045] a) an outlet nozzle for dispensing the product having a first intake end for taking up product from a container and a second dispensing end with a dispensing opening formed in the dispensing end and a mouth formed on the nozzle about the dispensing opening, the nozzle comprising a nozzle body with a conduit formed therein; [0046] b) a brush insert for application of the dispensed product having a brush body and a plurality of bristles extending therefrom, the brush insert adapted to be received into the nozzle body and retained therein so that the plurality of bristles protrude through the dispensing opening, the brush insert further having an inner surface defining a product flow passage through said brush insert, the flow passage in fluid communication with the conduit in the nozzle; [0047] c) a break-off cap comprising a cap body for closing the dispensing end of the outlet nozzle, the break-off cap having a first position wherein the cap body is integrally formed with the outlet nozzle to close the dispensing opening of the outlet nozzle and is connected thereto by at least one frangible connection, and a second position wherein the frangible connection is broken allowing removal of the cap and thus opening the dispensing opening thereby allowing product to be dispensed through the outlet nozzle. [0048] Desirably, the cap body and the outlet nozzle have interengaging formations for subsequently securing the break-off cap to the nozzle to close the outlet opening the interengaging formations being “snap-fit” formations that are disengageable from the interengaging position by relative rotation of the cap and the container. [0049] Typically, the bristles are integrally formed on the brush body. The brush insert may be moulded from a plastics material. [0050] In one embodiment, the plurality of bristles are formed in a ring. Alternatively, the plurality of bristles may be formed in a plurality of concentric rings. [0051] Desirably, the brush body is substantially cylindrical. [0052] Typically, the conduit defined by the inner walls of the nozzle body is substantially conical in shape, the inner wall of the nozzle body gradually decreasing in diameter from the first intake end to the dispensing end of the nozzle body. The brush insert is desirably adapted to be inserted into the conduit through the first intake end of the nozzle. [0053] Suitably, the outer diameter of the brush body is smaller than the internal diameter of the intake end of the nozzle body and substantially equal in diameter to the internal diameter of the dispensing end of the nozzle body so that the brush body is retained in the conduit by friction between the outer wall of the brush body and the inner wall of the nozzle body adjacent the dispensing opening. [0054] At least a portion of the brush body desirably extends through the dispensing opening. [0055] In a further aspect, the invention provides a squeezable dispenser for dispensing product comprising: [0056] a) a container for holding product to be dispensed, [0057] b) an outlet nozzle in fluid communication with the container for dispensing the product, the outlet nozzle having a dispensing end and a dispensing opening formed in the dispensing end, [0058] c) plurality of bristles retained within the outlet nozzle and protruding through the dispensing opening for application of the dispensed product, and [0059] d) a break-off cap comprising a cap body for closing the dispensing end of the outlet nozzle, the break-off cap having a first position wherein the cap body is integrally formed with the outlet nozzle to close the dispensing opening of the outlet nozzle and is connected thereto by at least one frangible connection, and a second position wherein the frangible connection is broken allowing removal of the cap and thus opening the dispensing opening thereby allowing product to be dispensed through the outlet nozzle. [0060] The cap body and the outlet nozzle may have interengaging formations for subsequently securing the break-off cap to the nozzle to close the outlet opening the interengaging formations being “snap-fit” formations that are disengageable from the interengaging position by relative rotation of the cap and the container. [0061] In a further aspect, the invention provides a brush insert for insertion into a dispensing nozzle suitable for dispensing from a hand-held phial, the brush insert comprising: [0062] a) a hollow cylindrical brush body having a inlet end and an outlet end, the internal walls of the brush body defining a product flow path through the cylindrical body between in inlet hole at the inlet end of the body and an outlet hole at the outlet end of the body, and [0063] b) a plurality of bristles extending away from the outlet end of the cylindrical body substantially parallel to the longitudinal axis of the brush insert, the plurality of bristles arranged around the outlet hole. [0064] The brush body and the plurality of bristles may be integrally formed. Desirably, the brush body and the plurality of bristles are integrally formed from an injection moulded plastics material. [0065] Typically, the plurality of bristles are arranged in at least one concentric ring around the outlet hole. [0066] The term “v-shaped” as used herein in relation to the present invention includes the convergence of two surfaces towards a point of coincidence, for example an apex, and includes surfaces which are curved and surfaces which do not converge at the same rate towards the point of coincidence. [0067] The term “ramped” includes both planar and curved sloped surfaces. It also includes those surfaces where the rate of incline changes. [0068] The term “blister” as used herein refers to a pack arrangement with at least two layers of material, one layer having (an array of) depressions formed in it and within which a container of the invention can be at least partially placed and a second layer for sealing to the first to close the pack about the, or each, depression. [0069] The term “pouch” as used herein includes a pack arrangement with a layer of material each side of the container, the layers being joined to each other to create a pocket or pouch (similar to a sachet) within which the container is held. The pouch is normally created by heat sealing (or welding) the layers to each other about the container. [0070] The term “strip” as used herein to refer to packaging includes a series of blisters wherein each container holding compartment (or “blister”) is frangibly connected to each of the other compartments to which it is attached, or a series (lines) of pouches which are frangibly connected one to the next. A strip is usually a single series of blisters or pouches. It will be appreciated that a series of blisters or pouches may be provided as an array such as described below. BRIEF DESCRIPTION OF THE DRAWINGS [0071] FIG. 1 is a front elevation of (an unfilled) container (with an open base) which incorporates features of the first and second aspects of the present invention; [0072] FIG. 2 is a side elevation view of the container of FIG. 1 ; [0073] FIG. 3 is a top plan view of the container of FIG. 1 ; [0074] FIG. 4 is an underneath plan view of the container of FIG. 1 (showing the view through the open base); [0075] FIG. 5 is a cross-sectional view of the container of FIG. 1 along the line A-A indicated in FIG. 3 ; [0076] FIG. 6 is a cross-sectional view of the container of FIG. 1 along the line B-B of FIG. 3 ; [0077] FIG. 7 is an enlarged partial front elevational view of the container of FIG. 1 showing the cap and nozzle of the container in larger dimensions; [0078] FIG. 8 is an enlarged partial side elevational view of the container of FIG. 1 showing the cap and nozzle of the container in larger dimensions; [0079] FIG. 9 is an enlarged partial cross-sectional view of the container of FIG. 1 (along the line A-A of FIG. 3 ) showing the cap and nozzle of the container in larger dimensions; [0080] FIG. 10 is an enlarged partial cross-sectional view of the container of FIG. 1 (along the line B-B of FIG. 3 ) showing the cap and nozzle of the container in larger dimensions; [0081] FIG. 11 is a partial view of the view of FIG. 9 enlarged to an even greater extent; [0082] FIG. 12 shows a perspective view of a container provided with a nozzle assembly of the invention having being filled (with a sealed base end); [0083] FIG. 13 is a perspective view of the container of FIG. 12 , the cap having being broken off from the container body; [0084] FIG. 14 is a perspective view of the container of FIG. 12 , the cap having being reversed and replaced (snap-fitted) on the container; [0085] FIG. 15 is an enlarged front sectional view of the nozzle and cap of the container of FIG. 14 (with the cap broken off, reversed (inverted) and replaced); [0086] FIG. 16 is a side cross-sectional view of the container of FIG. 14 (with the cap broken off, reversed (inverted) and replaced); [0087] FIG. 17 shows a part-sectional view of a nozzle assembly of the present invention wherein the cap has been broken-off, reversed and incorrectly aligned for replacement on the nozzle; [0088] FIG. 18 is a perspective view of a container incorporating a nozzle assembly of the present invention having inter-engaging formations on the cap and the nozzle in the form of screw-threads; [0089] FIG. 19 shows a perspective view of a nozzle assembly of the present invention for attachment to an existing container, which has been attached to a container tube; [0090] FIGS. 20 ( a )-( c ) show a blister-pack arrangement of the present invention; (a) is an exploded perspective view; (b) is a perspective view of the closed configuration and (c) is a perspective view of a single blister, with the flexible sealing layer partially peeled away; [0091] FIG. 21 shows an underneath plan view of a series of blisters arranged in a point of sale array; [0092] FIG. 22 shows a plan view of the point of sale array of FIG. 21 from one end thereof; [0093] FIG. 23 is a plan view of the point of sale array of FIG. 21 from one side thereof; [0094] FIG. 24 is a perspective view of the underneath side of the point of sale array of FIG. 21 ; [0095] FIG. 25 is an underneath plan view of an alternative series of blisters arranged in a point of sale array, and having a different array of blisters (as compared to the array of FIG. 21 ); [0096] FIG. 26 is a side elevational view of the point of sale array of FIG. 25 ; [0097] FIG. 27 is an underneath plan view of another point of sale array again having a different array of blisters; [0098] FIG. 28 is a side elevational view of the point of sale array of FIG. 27 ; [0099] FIGS. 29 ( a )-( c ) show: (a) an exploded perspective view of a pouch packaging (prior to assembly) according to the present invention; (b) an elevational view of a series of (four) pouches arranged in a tear-off strip; (c) a plan view of a single pouch; [0100] FIG. 30 shows a top plan view of a point of sale pouch array; [0101] FIG. 31 shows a side elevational view of the array of FIG. 30 ; [0102] FIG. 32 is diagrammatic representation of a point of sale array showing a container of the present invention in each compartment of the pack, the seal (closing) area about the container being shown with hatched lines; [0103] FIG. 33 shows a side part-sectional view of the arrangement of FIG. 32 where the array is a pouch pack array; [0104] FIG. 34 shows a side part-sectional view of the arrangement of FIG. 32 where the array is a blister pack array; [0105] FIG. 35 shows a point of sale blister pack array according to the present invention with exemplary product information printed on one side of the array; [0106] FIG. 36 shows a cross-sectional view of a container which incorporates a dispensing nozzle assembly in accordance with a further aspect of the invention; [0107] FIG. 37 shows a side cross-sectional view of the container of FIG. 36 ; [0108] FIG. 38 shows side elevation view of the brush insert of the container of FIG. 36 ; [0109] FIG. 39 shows a plan view of the brush insert of FIG. 38 ; [0110] FIG. 40 shows a side perspective view of an alternative embodiment of brush insert to that of FIG. 38 ; [0111] FIG. 41 shows a plan view of the brush insert of FIG. 40 ; [0112] FIG. 42 shows a cross-sectional view of the container of FIG. 36 in its pre-filled state (with an open base) before the brush insert is inserted; [0113] FIG. 43 shows a side cross sectional view of the container and brush insert of FIG. 42 ; [0114] FIG. 44 shows a cross-sectional view of the container of FIG. 42 in its pre-filled state with the brush insert inserted; [0115] FIG. 45 is a side cross sectional view of the container of FIG. 44 ; [0116] FIG. 46 is a perspective view of the container of FIG. 36 , the cap having been broken off the container ready for use. DETAILED DESCRIPTION OF THE INVENTION [0117] Certain embodiments of the present invention will be described below with relation to the above Figures. FIG. 1 shows a container 1 of the present invention, having a nozzle assembly (comprising a nozzle 3 and a cap 20 ) of the present invention integrally formed therewith. The container 1 has a hollow container body 2 for receiving and holding product which is placed in the container. An outlet nozzle 3 forming part of the container projects from the container body 2 . A first (intake) end 4 (of the nozzle 3 ) is located on the container body 2 , and in the embodiment illustrated, is integrally formed therewith. The outlet nozzle 3 has a second (free) dispensing end 5 with a dispensing opening 6 formed in the dispensing end 5 . A mouth or rim 7 is formed on the nozzle 3 about the dispensing opening 6 . The outlet nozzle 3 has a nozzle body 8 with a conduit 9 defined therein. The conduit 9 is bounded by an internal surface 10 of the nozzle body 8 . The conduit 9 is in communication with the interior 11 of the container body 2 and the dispensing opening 6 . A break-off cap 20 is located on the outlet nozzle 3 . The break-off cap 20 has a cap body 21 for closing the dispensing end of the outlet nozzle 3 . The nozzle 3 and the break-off cap form a nozzle assembly. Alternatively the nozzle 3 and the break-off cap could be formed as a nozzle assembly for attachment to an existing container, for example an aluminium tube container, as shown in FIG. 19 . In FIG. 19 the nozzle assembly 80 is attached to a tube 82 . The nozzle assembly is for the most part as described below in detail with references to FIG. 1 to 17 though in the embodiments of FIGS. 1 to 17 the nozzle assembly described is integrally formed with the container. In the embodiment of FIG. 19 the nozzle assembly 80 has at its first intake end 83 of the outlet nozzle 84 a skirt portion 85 which engages a neck of the tube 82 . The mode of engagement of the nozzle assembly 80 on the tube 82 is by any suitable method for example screw-threading or snap-fitting. In the embodiment of FIG. 19 the nozzle assembly may be provided as an accessory or attachment adapted for existing containers. [0118] In FIGS. 1-12 , 18 and 19 , the break-off cap is shown in a first position where the cap body 21 is integrally formed with the outlet nozzle 3 to close the dispensing opening 6 of the outlet nozzle 3 . A frangible connection 22 is formed between the nozzle 3 and the cap 20 . The frangible connection 22 can be broken to allow removal of the cap (see FIG. 13 ) and thus opening (uncovering) the dispensing opening 6 on the nozzle 3 . It is then possible to dispense product from the container 1 . The frangible connection 22 may be formed during integral moulding of the container 1 . The container is desirably constructed of a plastics material so that all components may be formed by a single moulding process. [0119] As best seen from the enlarged views of FIGS. 9-11 (and particularly from FIG. 11 ) an internal annular crotch 23 is formed between the nozzle 3 and the cap body 21 about the dispensing opening 6 . The crotch narrows in a radially outward direction (radially outwardly from the conduit 9 ) providing a generally v-shaped groove or recess at the junction between the cap 20 and the nozzle 3 . The weakened junction (the annular crotch 23 ) between the cap 20 and the nozzle 3 allows the cap 20 to be broken off from the nozzle 3 thus breaking the frangible connection 22 . The product can then be dispensed from the container. [0120] As best seen from FIG. 11 the cap body 21 has a recess, groove or housing 25 which is located to the exterior (of the cap body) of the cap. The housing 25 is formed in an external wall of the cap. The provision of housing 25 helps to ensure that no plastics material is inadvertently formed directly across the mouth 6 of the nozzle 3 during moulding of the container. It also allows for ease of break-off of the cap. Desirably the housing 25 has a mouth 26 which is shaped to mate with the mouth 7 (about the dispensing opening 6 ) of the nozzle 3 . Mating is achieved by the frangible connection 22 . [0121] The container body 21 as shown in FIGS. 1-6 is open at its bottom end 12 . As best seen from FIG. 4 the container body 2 depends from the nozzle 3 to form a skirt at its bottom end. The skirt is open forming a generally elongate aperture 13 defined by the bottom end 12 of the container body 2 . The aperture 13 is the aperture through which the product may be placed in the container. Once the container is filled to the desired level with product, the container bottom may be crimped or (heat-) welded (or indeed closed by any suitable method) along line 19 (see FIGS. 12-14 ) to seal the contents within the container. [0122] To aid gripping of the container 1 by the hand a thumb or finger grip (such as shown in FIGS. 1 , 2 and 6 ) for example in the form of a larger crescent-shaped upstanding grip 14 and a smaller (nested) grip 15 may be provided. The grips 14 and 15 may be provided on opposing sides of the container as seen in FIG. 2 . [0123] The nozzle 3 is tapered gradually reducing in dimensions from the container body 2 to the dispensing opening 6 . There is also a stepped reduction of the width of the nozzle 3 from the wider portion 16 to the narrower portion 17 which transition occurs at step or rim 18 . The step or rim 18 also provides a constriction of the conduit 9 . [0124] Two opposing sides of the reduced diameter portion 17 of the nozzle 3 , namely opposing sides 30 , 31 are flat (straight) while the two opposing ends 32 , 33 joining the flat sides 30 , 31 are curved. [0125] Each straight side 30 , 31 has, formed thereon, a projection respectively labelled 34 , 35 . The projections 34 , taper from respective (upper) positions 36 , 37 where they are flush with the reduced diameter portion 17 , downwardly and outwardly. The projection 34 , 35 end in respective rims or edges 38 , 39 . [0126] The cap 20 has a shape which resembles a wing nut having a central flat-sided oval shaped narrowing gradually toward its upper end portion 49 forming part of the cap body 21 , to which are attached wing shaped grips, which are respectively labelled 27 , 28 (see for example FIG. 7 ) on opposing sides of the flat-side oval portion 24 . Optional reinforcing tabs or ribs 40 are provided to strengthen the junction between the flat-sided oval portion 24 and the wings 27 , 28 . [0127] To reinforce the (inverted) attachment of the break-off cap 20 to the nozzle 3 two further frangible connections 41 , 42 are integrally formed one between each of respective lugs 43 , 44 on the wings 27 , 28 and the exterior of the nozzle 3 . [0128] The break-off cap 20 is held in an inverted position on the outlet nozzle before it is broken off. In this arrangement an outer surface, namely the surface of the recess or groove 25 closes the dispensing opening on the container. The break-off cap is reversible so that when broken off, (see FIG. 13 ) the cap may be inverted for subsequent replacement onto the container (see FIG. 14 ). [0129] In this regard it is worth noting that the cap 20 , and in particular the generally flat-sided oval portion 24 (see FIG. 7 ), forms a housing 50 into which at least a portion of, and in particular the dispensing end 5 of the nozzle 3 is insertable. As can be seen from the Figures the generally flat-sided oval portion 24 matches the profile of the reduced circumference portion 17 of the nozzle 3 and snugly overfits it. In particular the generally flat-sided oval portion 24 comprises a housing 50 defined by two opposing side walls 51 , 52 in each of which are formed one of two windows or apertures respectively labelled 53 , 54 . The windows or apertures 53 , 54 are designed to be snap-fit engageable with the projections 34 , 35 . The windows 53 , 54 are cut-out portions of the side walls 51 , 52 and are generally of rhombehedral shape. When the cap 20 is snap-fitted onto the nozzle 3 (as best seen from FIGS. 14 and 16 ) lower (transverse) wall portions 55 , 56 engage underneath the rims 38 , 39 of the (inverted) cup-shaped projections 34 , 35 . As best seen for example from FIGS. 3 , 12 and 13 the shape of the housing 29 reflects that of the nozzle with the two flat sides 51 , 52 which are joined by curved ends 57 , 58 . The mouth 59 of the housing 50 is thus of an oblong shape, and may be considered as a straight or flat-sided oval shape. [0130] A front sectional view of the container of FIG. 14 is shown in an enlarged partial view in FIG. 15 . In FIGS. 11 and 15 it can be more clearly seen that the nozzle 3 has at its dispensing end 5 and on two opposites side of the mouth 6 two recess portions 60 . The recess portions 60 form a seat for a seat engaging portion 65 on the cap. The seat-engaging portion 65 on the underside of the cap has two parts, a first part 66 (see FIG. 11 ) which is a first seat-engaging-portion which co-operates with tabs 68 (see FIGS. 12 and 13 ) on the nozzle 3 and a second seat-engaging-portion 67 which is dimensioned to engage the first seat-engaging-portion 66 . The relative positioning of the seat-engaging-portion 66 and the tabs 68 ensure the desired orientation of the cap and the nozzle (and thus the container) is achieved, as the cap and the nozzle will not mate if the seat-engaging-portion 66 and the tabs 68 abut. The seat-engaging-portion 66 and the tabs 68 abut if the cap is incorrectly orientated. The cap may be correctly guided onto the nozzle by interaction of the tabs 68 and the seat-engaging portions 66 and 67 , and is then seated on the nozzle. Incorrect alignment is shown in FIG. 17 . In the incorrect alignment of FIG. 17 lower wall portions 55 , 56 engage recess portions 60 so that recess portions act as stops preventing the cap from being placed over the nozzle. [0131] The cap 20 when in place on the nozzle is held thereto by inter-engagement of the projections 34 , 35 in the windows or apertures 53 , 54 as shown in FIG. 14 where the cap 20 has been snap-fitted to the nozzle 3 . In the closed configuration (see FIGS. 11 , 15 and 16 ) projecting portion or projection 61 (which is generally conical in shape and thus triangular in cross-section) protrudes into the conduit 9 engages the mouth thereof and providing a reliable seal for the container. It will be appreciated that due to the provision of the crotch or annular recess 23 between the nozzle 3 and the cap 20 , the shoulder portions 62 of the nozzle inside the mouth 6 abut exterior walls 63 , 64 of the conical projection 61 . The projection 61 may alternatively be of any shape suitable to provide a seal for the dispensing opening 6 . There is thus provided a reliable sealing arrangement so that even if remnants of frangible connection 22 were to be left at the top of the nozzle, these will not interfere with the closing action of the cap. In particular, and as best seen from the enlarged view of FIG. 11 the shoulder portion 62 can be considered to be a ramped surface running from the internal surface of the nozzle defining the conduit, to the mouth of the nozzle. The ramped surface 62 is annular and is generally frusto-conical in shape (in particular narrowing in diameter down the nozzle 3 ). The conical shaped projecting portion 61 and the ramped surface act as a plug and socket type arrangement, the projection portion 61 plugging the dispensing opening of the nozzle 3 by engaging the ramped surface 62 . [0132] Alternatively as is shown in FIG. 18 the inter-engaging formations may be screw-threads such as the thread 70 of FIG. 18 with a corresponding thread within the housing 50 . In this embodiment the cap 71 which is similar in construction to cap 20 does not have the oblong shape of the mouth of the cap 20 . As the cap 71 and the nozzle 72 interengage by means of reciprocal screw-threads (which necessitates relative rotation), the nozzle and the housing 50 of the cap are generally conical in shape. The cap 71 may be otherwise the same in construction to cap 20 . [0133] As seen in the Figures and in particular the enlarged view of FIGS. 7-11 , there is also formed an external annular crotch 45 . The crotch 45 narrows in a radially inward direction (radially inward toward the conduit 9 ). The crotch 45 is formed on the exterior of the container between the cap 20 and the nozzle 3 (in particular the mouth 7 of the nozzle 3 ). In particular the crotch 45 is formed by two (radially) inwardly converging surfaces—namely the outer surface 46 on the cap 20 and the outer surface 47 on the nozzle 3 . The surfaces 46 and 47 converge to form an apex 48 of the crotch. There are thus provided two opposing crotches which are located on either side of the frangible connection 22 . This double crotch arrangement allows for ease of removal of the cap 20 . The crotch 45 is v-shaped. The container of the invention is suitable for use with many products including in particular liquids and gels. The container will normally be designed to hold a relatively modest volume for example from about 0.5 to about 5.0 grams, such as about 1 gram or about 2 grams. The container may be crimped (heat-welded) at any part along its length (and above the fill-level in the inverted position) and bottom end 12 may be of a desired shape to facilitate ease of closure of the container. For light-sensitive materials opaque materials may be used to construct the container. [0134] FIG. 20 shows a blister pack array of the present invention in a pre-form assembly. The blister pack 100 is shown in exploded view. The blister pack comprises a semi-rigid material, such as aluminium in the form of a preform 101 . The preform 101 is a sheet 102 of deformable material such as aluminium material into which have been pressed (or punches) depressions or blisters 103 . Each of the blisters 103 is shaped to receive and at least partially contain a container 104 . Only one container 104 is shown in FIG. 20 , though it will be appreciated that a container 104 may be placed in each of the blisters 103 . The container 104 shown in FIG. 20 is diagrammatically drawn for the purposes of illustration only. In practice a container according to the present invention (as described above) may be placed within the blister pack. [0135] To complete the package a flexible sheet of material 105 such as a foil, for example an aluminium foil, may be used. The sheet 105 corresponds generally in shape to the preform 101 . The sheet 105 is attached to the preform. Normally, such attachment is achieved by heat and pressure sealing of the materials used. However in order to achieve re-sealing, resealing means for example a suitable adhesive which retains sufficient bonding capability to allow re-sealing of the pack could be used. This secures each container 104 within the pack, one in each blister 103 . The person skilled in the art will appreciate how to assemble such a blister pack for example by the materials described or by cold form methods. [0136] As shown in FIG. 20 ( b ) the sheet 102 has been sealed to the preform 101 . The sheet 102 (and the preform 101 where necessary) have been cut to a desired shape with rounded edges 106 and a series of cut-out portions or crotches 107 . A crotch 107 is provided on either side of the frangible connection 108 . The frangible connection 108 is machined into the pack (for example as a score line or as a series of perforations) and allows for breaking-off of a single “blister” 109 (as shown in FIG. 20 ( c )) thus creating a tear-off strip form of blister packaging. A single container 104 is contained within each blister 109 . The blister pack shown in FIG. 20( b ) is a single strip of blister. It will be appreciated that multiple strips or arrays are also possible and are described below. [0137] The crotches 107 on either side of the frangible connection 108 allow for ease of tear-off or break-off of successive blisters. It is intended that in a point of sale display array or strip each blister is easily detachable from the next thus allowing the blisters to be sold individually while being conveniently arranged for display. [0138] As shown in FIG. 20 ( c ) the blister is formed with a discrete blister cover 110 which may be peeled back from the blister tray 111 . The sheet 110 has a corner portion 112 [which is shown in dashed outline in the closed position in FIG. 20 ( c )] which protrudes beyond the blister tray 111 . This allows the blister cover 110 to be peeled back from the rim 113 of the blister tray 111 . The corner portion 112 thus acts as a pull-off tab, allowing the cover 110 to be easily pulled off manually. The blister cover 110 may be resealable to the blister tray 111 . This may be achieved by using a suitable adhesive which does not loose its tackiness to hold the blister cover 110 to the blister tray 111 . [0139] A point of sale display blister pack array 120 is shown in FIG. 21 . In the array 120 there are four rows and three columns in a 4×3 arrangement. The blisters 121 are provided in a preform 122 . Also provided on the preform 122 is a planar tab 123 which has defined therein an elongate aperture 124 which extends upwards in a further groove 125 to provide means for hanging the point of display array 120 on a display hook (or hanger). The tab 123 may be integrally formed with the blister pack, or may be attached separately. If not integrally formed the tab can be constructed or other materials, such as cardboard. To facilitate removal of individual blisters, a series of apertures scores or cut-outs and the like may be created in the preform 122 . The cut-out consist of two different types of apertures respectively labelled 126 and 127 . [0140] The apertures 126 are generally triangular in shape, forming a cut-away portion or crotch 128 between successive blisters 121 in the same row. Where blister 121 occurs at a position in the array where it must be separable from a blister directly beneath it in the column, and simultaneously any adjacent blisters in the same row, a star-shaped aperture 127 is provided. Each “leg” or apex of the star provides a crotch 128 . Frangible connections may be provided (for example simultaneously with sealing the container closed) across and down the array between the rows and the columns to form a grid or array of blisters each of which are frangibly connected to the other. The frangible connection may be provided by partial cut away along a line joining the apertures 126 , 127 in the row direction or in the column direction. [0141] An end view of the array of FIG. 21 is shown in FIG. 22 . A side-view thereof is shown in FIG. 23 . A perspective view is shown in FIG. 24 . [0142] FIG. 25 shows an underneath (plan) view of a point of sale display array 130 which is very similar to the array of 120 of FIG. 21 . The array 130 has six rows and two columns defining a 6×2 arrangement. In this arrangement a generally triangular shaped aperture 131 , and general star-shaped apertures 132 are provided again to allow for ease of removal of the blister 133 . The break away facility may be provided by scores, slits and/or apertures of alternative shapes to those described. Again cut-away portions or crotches 134 are provided along one side of the array 130 . On the other side a series of cut-away portions 135 are also provided to allow for ease of removal. The cut-away portions 135 have one generally straight upper side 136 and a lower corner side 137 which converge inwardly toward a line along which a frangible connection may be provided. This arrangement also allows for ease of removal of the individual blister. A side elevational view of the array 130 is shown in FIG. 26 . [0143] A similar array 140 is shown in FIGS. 27 and 28 , although in this case five rows and two columns are provided in a 5×2 arrangement of blisters 141 . Again cut-away portions are provided for ease of removal of individual blisters 141 . Certain materials useful in the construction of the blister pack include a laminate consisting of the following 3 layers: 30 μm paper/12 μm polyester/20 μm polyvinyl chloride. The preform may be constructed of the following four layered laminate: 60 μm polyvinylchloride/25 μm polyamide/60 μm aluminium/60 μm polyvinyl chloride. It will be appreciated by those skilled in the art that many sorts of suitable materials can be used. [0144] FIG. 29 shows various views of a pouch assembly 150 of the present invention. FIG. 29( a ) is an exploded view of an arrangement for creating a pouch strip 150 of the present invention. In particular the assembly comprises two opposed sheets of flexible material namely an upper sheet 151 and a lower sheet 152 between which is disposed a container 153 . Like the container 104 of FIG. 20 , the container 153 is shown for diagrammatic purposes. It is desirable that the container 153 is a container according to the present invention. The upper and lower sheets 151 , 152 are each generally rectangular in shape and of the same size. The sheets 151 , 152 may be made of an aluminium material, such as for example a laminated aluminium foil. [0145] To create individual pouches 154 the two sheets 151 , 152 are brought together and joined to each other about the container 153 . In the arrangement shown in FIG. 29( b ) four containers 153 have been sealed within four pouches, one in each pouch 154 . Each container 153 is then in a individual sachet, the sachets being connected in a tear-off strip arrangement. [0146] In the blister pack arrangement of FIG. 29( b ) while the sheets 151 , 152 are being attached to each other about the containers 153 , they may also be provided with frangible connections 155 and cut away portions 156 at the same time. The sheets 151 , 152 may be adhered to each other. Alternatively they may be welded or fixed together by any other suitable method. [0147] The cut-away portions 156 allow for ease of removal of the individual pouches 154 from each other. In particular the cut-away portions 156 comprise a crotch portion 157 which is generally v-shaped. The crotch portion 157 converges to the point of convergence 158 where the crotch portion terminates. There is then formed a further v-shaped recess 159 which acts as a tear-open notch when it is desired to (tear) open the pouch to remove the container inside for use. This is achieved by manually applying a shear or tear-open force at the tear-open notch. The pouch tears allow across to the container inside. An individual pouch 154 is shown torn away from the strip of pouches in FIG. 29( c ). The sealed (joining) area about the container can be seen as peripheral rim 160 . [0148] A point of sale array 170 of pouch packs 173 are shown in FIGS. 30 and 31 . The arrangement shown has five columns and two rows in a 5×2 arrangement. The array 170 has a tab 171 in which is defined an aperture 172 which allows an array of pouches to be hung on a hook in a manner described previously above. [0149] In the array 170 each of the pouches 173 is (transversely) frangibly connected to part of the array above and below by transverse frangible connections 174 . The pouches 173 may be separated from each other by a longitudinal frangible connection 175 . Each pouch 173 may be turn or broken away as it frangible from all other blisters to which it is connected. [0150] The ends 176 , 177 are not directly supported by the container inside and thus flatten down to provide dished or flattened ends 176 , 177 which are generally u-shaped, the shape of the container (the contents of the pouch) is taken up by both sheets 151 , 152 as can be seen from the side view of FIG. 31 . [0151] As described above for FIG. 29 , cut-out portions 178 , generally in the form of v-shaped crotches, are provided on one end of the array between each of the pouches 173 , and between the uppermost blister and the tab. On the opposing side of the array and along the frangible connection 174 cut-out portions or crotches 179 are also provided to allow for ease of the attachment of blisters. Between the uppermost row of pouches and the tab 171 an aperture 180 is provided and is generally triangular in shape with three apexes. The apertures 181 between subsequent rows are generally star-shaped with four apexes. [0152] Each of the apertures 180 , 181 extends along the frangible connection 174 and terminates at a point of convergence 183 . A tear-open notch 182 is then provided for each of the pouches 173 on the other side of the point convergence 183 . FIG. 31 is a side elevational view of the pack of FIG. 30 . [0153] FIG. 32 is a diagrammatic representation, in part-sectional view, of a blister pack or a strip pouch according to the present invention in which a container 190 is located in each of the blisters or each of the pouches. The container 190 is a container according to the present invention having an internal annular crotch to allow break-off of the cap 191 as described above. The hatched area 192 indicates the areas sealed between the two flexible sheets sealed together about the container, where the array is a pouch array, or the area between the preform and the flexible sheet sealed together where the array is a blister array. [0154] The container 190 differs from the containers described previously in a number of relatively minor respects. These includes rims or wings 193 provided on opposing sides of the container which allow for ease of manual handling. The cap 191 has internal threads 194 which engage with reciprocal threads 195 on the nozzle of the container. The cap 191 also has two opposing wings or grips 196 which allow for ease of handling of the cap 191 . A side, part-sectional view of a pouch arrangement is shown in FIG. 33 . The blister array is shown in side, part-sectional view in FIG. 34 . [0155] A point of display array 198 is shown in FIG. 35 . The array has three columns and four rows (3×4). As can been seen printed matter 199 has been applied to the flat side of the blister pack. [0156] Methods of preparing the types of packaging described will be known to those skilled in the art. In this respect particular mention is made of a method of packaging often referred to as “flow wrapping”, “flow pack(ing)” or “tube wrap(ing)”. This is a type of packaging which seals in articles. The seal produced on a horizontal or vertical “form-fill-seal” wrapping machine generally associated with wrapping irregular-shaped items (such as candy bars and bakery items). In general the “form-fill-seal” operation is carried out as follows: a reel (web) or reels of flexible packaging material is formed into a container, filled and sealed in one series of operations to produce a package, containing a predetermined quantity of product. [0157] Form-fill-seal operations (flow packing) can be carried out in three main ways: [0158] (a) a web of material may be formed into a tube which is filled and sealed at intervals; [0159] (b) a web of material may be folded along its length, sealed at intervals to form a series of pouches (sachets) which are then filled and closed; and [0160] (c) a web of material may be thermo-formed to give a series of tray like depressions which are filled, and then sealed by means of a second web. [0161] FIGS. 36 and 37 show a container of the present invention having a nozzle assembly of the present invention integrally formed therewith. [0162] In this embodiment, the nozzle is integrally formed with the container. However, it will be appreciated that the nozzle and its break-off cap could be formed as a nozzle assembly for attachment to an existing container, for example an aluminium tube container. The mode of engagement of the nozzle assembly on the tube may be by any suitable method for example screw-threading or snap-fitting. The nozzle assembly may be provided as an accessory or attachment adapted for existing containers. [0163] The container of FIG. 36 is identical to that shown in FIG. 1 , save for the following detail. [0164] The nozzle assembly comprises a brush insert 300 for application of the dispensed product to a surface. The brush insert is shown in detail in FIG. 38 . The brush insert is comprised of a brush body 302 and a plurality of bristles 304 extending therefrom (upstanding thereon). The brush body 302 is substantially cylindrical and hollow having an input end 303 and an output end 305 . The inner surface 306 of the brush body defines a product flow passage 308 which extends along the longitudinal axis of the brush insert. [0165] The bristles 304 extend from the outlet end 305 of the brush body. The bristles 304 are aligned substantially parallel to one another and substantially parallel to the longitudinal axis of the brush insert. The bristles are circumferentially arranged about the longitudinal axis, and there are no bristles arranged above the passage 308 . All bristles are arranged about the passage. Both the fixed ends and the free ends of the bristles are arranged about the passage. [0166] The brush insert is injection moulded from a plastics material such as low density polyethylene or polypropylene. These materials are used for their low reactive properties with adhesives or other curable substances which the dispenser may be used to dispense. Although the bristles may temporarily harden between uses of the dispenser to dispense adhesive, they will not gel or lock together and prevent subsequent re-use of the dispenser. The insert is particularly useful for dispensing cyanoacrylate adhesive. It will be appreciated that any cyanoacrylate adhesive compatible material may be used for the manufacture of the insert. [0167] The brush insert is formed as a single piece, with the bristles integrally formed on the brush body. [0168] As shown in FIG. 39 , the brush insert comprises a total of ten bristles, arranged in a annular pattern or ring about the opening of the flow passage 308 . [0169] An alternative embodiment of brush insert is shown in FIGS. 40 and 41 . The brush insert 400 has a total of sixteen bristles 404 arranged in two concentric rings about the opening of the flow passage 308 . [0170] It will be appreciated that in alternative embodiments of brush insert, three or more concentric rings of bristles may be provided about opening of the flow passage 308 . [0171] It will further be appreciated that the brush insert may comprise any number of bristles in any arrangement about the passage. [0172] The brush insert provides in the dispenser a flow-through brush. The central passage 308 allows product to be dispensed through the brush body, out of the passage opening and into the vicinity of the bristles, where it can be applied with the bristles. These dimensions/arrangement of the bristles is such that that they take up product dispensed through passage 308 . [0173] The brush insert 300 is adapted to be received into the nozzle body 208 and retained therein. FIGS. 42 and 43 show the inverted (pre-fill) pack ready to receive the brush insert 300 . [0174] The brush insert 300 is inserted bristle end first into the pack through its open end 212 . [0175] As seen in FIG. 42 , the conduit 209 defined by the inner walls 210 of the nozzle body 208 is substantially conical in shape. The inner wall 210 of the nozzle body gradually decreases in diameter from the first intake end 204 adjacent the container body to the dispensing end 205 of the nozzle body. [0176] As the brush insert 300 is a placed or fed into the interior 210 of the container 201 of the pack, the inner walls of the container portion will guide the brush insert 300 into the nozzle conduit 209 . [0177] The outer diameter of the brush body 300 is smaller than the internal diameter of the intake end 204 of the nozzle body and substantially equal or slightly larger in diameter to the internal diameter of the dispensing end 205 of the nozzle body. [0178] Pressure is then applied to the end 303 of the brush insert distal to the bristles in the direction of the nozzle to force the brush insert 300 into the desired position inside the nozzle conduit 209 . [0179] FIGS. 44 and 45 shows the brush insert 300 in the desired position in the nozzle. [0180] As the outer diameter of the insert is substantially equal in diameter to or slightly larger than the internal diameter of the dispensing end 205 of the nozzle body, a tight fit inside the nozzle conduit is achieved. [0181] The brush body 300 is retained in the conduit by a frictional force between the outer wall 310 of the brush body and the inner wall 210 of the nozzle body adjacent the dispensing opening. [0182] It will be appreciated that at least a portion of the length of the bristles are arranged to protrude through the dispensing opening of the nozzle. A variation of length protruding is achieved by selecting the position of the insert of the nozzle conduit. In the embodiment shown in FIG. 44 , the entire length of bristles are arranged to protrude through the opening. [0183] Generally, it is desirable that at least a portion of the brush body also extends through the dispensing opening. This helps to prevent the bristles from being sheared off the brush body as the frangible connection between the cap and the nozzle outlet is broken (as described below). [0184] The flow passage in the brush insert provides a communication path between the product intake end of the nozzle and the dispensing opening of the nozzle adjacent the bristles. [0185] After the insert is in position inside the nozzle, the container body is then ready for filling through, and sealing along, its base 212 . [0186] Referring back to FIGS. 36 and 37 , the break-off cap 220 is shown in a first position where the cap body 221 is integrally formed with the outlet nozzle 203 to close the dispensing opening 206 of the outlet nozzle 203 . As with previous embodiments, a frangible connection 222 is formed between the nozzle 203 and the cap 220 . [0187] In this first sealed position the portion of bristles extending beyond the frangible connection point are received into the recess 225 in the cap body. [0188] The frangible connection 222 can be broken to allow removal of the cap as shown in FIG. 46 . The removal of the cap opens (uncovers) the bristles 304 and the dispensing opening 206 on the brush insert. It is then possible to dispense product from the container 201 . [0189] When the cap is inverted and re-engaged with the nozzle after use, in the manner described with reference to the embodiment of the container of FIGS. 14 to 16 , the bristles protruding from the nozzle are received and sealed within a second recess or housing 229 provided at the end of the cap body opposite the first recess 225 . [0190] The embodiment of container shown in FIGS. 36 to 46 can be used to control the application of the dispensed product. The brush can be used, for example, to spread the product across a surface. Alternatively, the brush may be used to apply a small precise amount of product to a small area. [0191] It will be appreciated that a further advantage of the brush is that it allows a controlled continuous dosage of product to be dispensed.

A nozzle assembly ( 3, 20 ) with a re-useable break off cap ( 20 ) for dispensing a product from a container ( 1 ). On a dispensing end ( 5 ) of the nozzle ( 3 ) a break-off cap ( 20 ) is integrally formed thereon and closes off the dispensing end ( 5 ) of the nozzle ( 3 ). The break-off cap ( 20 ) is removable by breaking a frangible connection ( 22 ) between the nozzle ( 3 ) and the break-off cap ( 20 ). Removing the break-off cap opens the dispensing end ( 5 ) of the nozzle ( 3 ) thereby allowing product to be dispensed through the nozzle ( 3 ). The break-off cap ( 20 ) removed from the nozzle ( 3 ) can then be re-engaged with the nozzle ( 3 ) to close off the dispensing end ( 5 ) thereby preventing further product from being dispensed. The cap can be attached to or removed from the nozzle ( 3 ) as often as a user requires. Packaging which includes a tray ( 111 ) or pouch into which the nozzle assembly ( 3, 20 ) and container ( 1 ) can be inserted. A flexible resealable peel-off cover ( 110 ) is provided on each tray ( 111 ) to allow a user to resealably open and close the tray ( 111 ). The resealable tray ( 111 ) can be provided either singly or as a series of trays. The nozzle assembly may also incorporate an applicator for application of the dispensed product.

CROSS-REFERENCE TO RELATED APPLICATION This application claims benefit under 35 USC 119 of Provisional Application No. 61/030,654 filed Feb. 22, 2008, the entire disclosure of which is hereby incorporated by reference herein for all purposes. BACKGROUND OF THE INVENTION The subject matter disclosed in this application relates to a system and method for protecting an extended passive optical network (PON). Network operators deliver Internet, television and telephone services to consumers using fiber-to-the-premises (FTTP) architectures. Many of these deployments have used PON, rather than point-to-point access networks. Referring to FIG. 1 of the drawings, an Optical Line Termination (OLT) 10 in a telephone company central office connects to service platforms, such as Internet broadband network gateways (BBNG), Internet Protocol Television servers, and Voice over IP gateways, typically via a metro network 12 , and a PON connects the OLT 10 to Optical Network Terminations (ONTs) 14 . In typical single family dwelling units, the ONT is located in or attached to the exterior of the home. In typical multifamily dwelling units, the ONT is located in a common utility space or located inside individual living units. In either case, the ONT derives service interfaces, such as Ethernet, cable television and analog phone, from the signal on the PON. The PON comprises a feeder fiber 16 that connects the OLT to a passive remote node that includes an optical power splitter 18 . Typically, the splitter has a split ratio of 16:1, 32:1 or perhaps 64:1, depending on the optical power budget of the network. The fan-out ports of the splitter are connected to distribution fibers 22 , each of which is further connected to an ONT 14 via a drop fiber (not separately shown). Under current industry practice, such a network may utilize an optical carrier at 1490 nm for downstream communication (i.e. transmission of bitstreams from the OLT to the customers' ONTs) and may utilize an optical carrier at 1310 nm for upstream communication (i.e. transmission of bitstreams from the customers' ONTs to the OLT). The total reach of the PON, i.e., the maximum of the sum of the length of the feeder, distribution and drop fibers, is determined by the optical power budget of the system and the split ratio of the optical splitter. For example, ITU-T Recommendation G.984.2amd1 specifies an optical power budget of 28 dB. This equates to 20 km reach with a 32:1 split ratio, or 10 km reach with a 64:1 split ratio. While 20 km reach is adequate for many deployments, a network operator often needs a longer reach. For example, homes in rural areas might not be within 20 km of a central office. Further, a network operator may wish to reduce the number of central offices in its network so as to eliminate cost. As shown schematically in FIG. 2 , the effective reach of a PON may be extended by connecting the OLT to the upstream end of the feeder fiber 16 through a backhaul fiber 30 and an extender 26 including gain elements 32 which produce optical gain and thereby increase the optical power budget of the PON. The upstream and downstream signals are separated by wavelength division multiplexers 34 . One or both gain elements may be implemented by a semiconductor optical amplifier (SOA). An SOA is enabled by applying bias current to the SOA, in which case the SOA exhibits gain; it is disabled by removing bias current from the SOA, in which case the SOA exhibits a high extinction ratio. Alternatively, one or both gain elements may be a doped fiber amplifier, such as an erbium doped fiber amplifier, which may be enabled by applying bias current to the pump laser, in which case the amplifier exhibits gain; it may be disabled by removing bias current from the pump laser, in which case the doped fiber absorbs light. A third possibility is to implement one or both gain elements with an optical to electrical to optical (OEO) regenerator, which recovers the optical signal, converts it to electrical form, possibly recovers and regenerates timing, converts the electrical signal back to optical form, and transmits the regenerated optical signal. An OEO may be enabled by completing the transmit path in the regenerator, including its receiver, clock/data recovery, buffering and transmitter, and may be disabled by turning off any part of the transmit path (but most conveniently the transmit laser). The resiliency of an extended PON is a concern for network operators. Vulnerability of fiber to breakage, e.g., due to accidental dig-ups, is roughly proportional to its length, and an extended PON by definition has longer fiber sections than a standard PON. Further, an amplified PON may serve more subscribers than a standard PON or a regenerator extended PON and these additional subscribers constitute a larger shared risk group. Further, recent events have heightened sensitivity to the time required to restore service in the event of loss of a central office, e.g., due to a flood, fire or act of terrorism; at the same time, if a network operator attempts to reduce the number of central offices in its network, a larger number of subscribers will be served from each central office. Thus, it is desirable to provide a protection scheme that will protect against failure of at least the feeder fiber, the backhaul fiber, the extender, and the OLT. A protected extended PON may comprise a plurality of ONTs, with drop and distribution fibers, and a remote node, as in a standard PON; and a working entity and a protection entity, wherein each entity of the working and protection pair comprises an OLT, a backhaul fiber, an extender unit, and a feeder fiber. The two feeder fibers may be diversely routed; the two backhaul fibers may be diversely routed; and the two OLTs may be located in the same central office or in different central offices. The two feeder fibers feed respective fan-in ports of a 2:N optical power splitter. Advantageously, optical power is distributed equally in the downstream direction from each fan-in port, and equally in the upstream direction to each fan-in port; thus, there is no optical power penalty to, e.g., a 2:64 power splitter relative to a 1:64 power splitter However, a problem arises with such a topology. The 2:N splitter is an entirely passive device, and thus signals from both OLTs pass through it to the ONTs. If there were two such signals, they would mutually interfere. Thus, it is necessary to ensure that downstream signals from only one OLT at a time reach the splitter. This may be accomplished by ensuring that only one OLT of the working and protection pair is enabled at a time and either disabling or suppressing the downstream signal of the other OLT. The enabled and disabled states must be reversed in the event that a fault is detected, but only if the protection entity is intact. ITU-T Recommendation G.983.5 describes several protection schemes for unextended PONS. Type B protection protects the feeder and OLT line terminations, but not the ONTs. Type C protection also protects ONTs, and thus solves a different problem. Notably, working and protection OLT line terminations must be in the same chassis. This means that no protection is provided in the event of loss of a central office. Past approaches to the problem of protecting an unextended PON have used line terminations within a single OLT chassis and have been coordinated by local mechanisms within the chassis. Extending the problem to OLTs which are not collocated raises the problem of coordination between potentially distant chassis. An extended PON creates the possibility of various failure modes, which could lead to false detection of a fault or failure to detect a fault in a working PON. For example, if the protection OLT were to simply perform protection switching when it detected a loss of signal from the PON, a fault in the upstream path of the protection extender would result in a false detection. Similarly, if the protection OLT were to depend upon a failure signal from the working OLT to determine a failure, then a fault in the communication path between the two OLTs would result in either failure to detect a subsequent fault in the PON, or immediate false detection. A person sufficiently skilled in the art of protocol design may be able to identify and devise ways to remedy these problems but the resulting mechanism may be complex and unwieldy in ways that may create exposure to implementation defects. If fault detection is located in the OLT, faults that affect one direction of transmission in the extender cannot be detected. SUMMARY OF THE INVENTION In accordance with a first aspect of the disclosed subject matter there is provided extender apparatus for an optical network, comprising a first extender unit having an network-facing port for connection to a first backhaul fiber and a subscriber-facing port for connection to a first feeder fiber and including a first gain assembly, the first extender unit being operable selectively either in an enabled state, in which the first gain assembly amplifies a signal received at either port of the first extender unit and couples it to the other port of the first extender unit, or in a disabled state, in which the first gain assembly blocks coupling of a signal from either port of the first extender unit to the other port of the first extender unit, a second extender unit having an network-facing port for connection to a second backhaul fiber and a subscriber-facing port for connection to a second feeder fiber and including a second gain assembly, the second extender unit being operable selectively either in an enabled state, in which the second gain assembly amplifies a signal received at either port of the second extender unit and couples it to the other port of the second extender unit, or in a disabled state, in which the second gain assembly blocks coupling of a signal from either port of the second extender unit to the other port of the second extender unit, and a failover unit that is operable when the first extender unit is in the enabled state and the second extender unit is in the disabled state to detect occurrence of at least one fault condition in the first extender unit, the failover unit being responsive to said fault condition in the first extender unit to switch the first extender unit to the disabled state and the second extender unit to the enabled state. In accordance with a second aspect of the disclosed subject matter there is provided an optical network comprising first and second backhaul fibers each having an network-facing end for coupling to an optical line termination and also having a subscriber-facing end, first and second feeder fibers each having a subscriber-facing end for coupling to at least one optical network termination and also having an network-facing end, first and second extender units having respective network-facing ports coupled to the downstream ends of the first and second backhaul fibers respectively and respective subscriber-facing ports coupled to the upstream ends of the first and second feeder fibers respectively, and each extender unit including a gain assembly and being operable selectively either in an enabled state, in which the gain assembly amplifies a signal received at either port of the extender unit and couples it to the other port of the extender unit, or in a disabled state, in which the gain assembly blocks coupling of a signal from either port of the extender unit to the other port of the extender unit, and a failover unit that is operable when the first extender unit is in the enabled state and the second extender unit is in the disabled state to detect occurrence of at least one fault condition in the first extender unit, the failover unit being responsive to said fault condition in the first extender unit to switch the first extender unit to the disabled state and the second extender unit to the enabled state. In accordance with a third aspect of the disclosed subject matter there is provided a computer readable medium containing instructions that, when executed by a computer that operates as a failover unit in optical network extender apparatus and receives a signal indicating occurrence of a fault condition in the working extender unit of a working and protection pair of extender units, causes the failover unit to issue signals causing the working extender unit to switch to a disabled state and the protection extender unit to switch to an enabled state. BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: FIG. 1 is a simplified block schematic diagram of a passive optical network (PON), FIG. 2 is a simplified schematic block diagram of an extended PON, FIG. 3 is a simplified block schematic diagram of a first extended PON in an illustrative embodiment, FIG. 4 is a simplified block schematic diagram of a second extended PON in an illustrative embodiment, and FIG. 5 is a simplified schematic block diagram of a computer that may be used in implementation of an illustrative embodiment. DETAILED DESCRIPTION FIG. 3 illustrates an extended PON that includes a working entity and a protection entity, and each entity of the working and protection entity pair includes a backhaul fiber 30 , an extender 40 and a feeder fiber 16 . The feeder fibers are coupled to respective fan-in ports of a 2:N power splitter 42 having fan-out ports connected through distribution and drop fibers to respective ONTs. The two OLTs, of the working and protection entities respectively, may be collocated or distant. The working and protection entity pair implement a 1+1 protection scheme, i.e. a protection scheme that carries productive traffic in the working entity or the protection entity but not both at the same time. As shown in FIG. 3 , each extender 40 A, 40 B comprises wavelength division multiplexers (WDMs) 44 D and 44 U that are connected to the backhaul fiber 30 A, 30 B and feeder fiber 16 A, 16 B respectively. The downstream signal passes from the backhaul fiber to the feeder fiber via the WDM 44 D, a fiber segment 52 D, a gain element 48 D, a fiber segment 54 D and the WDM 44 U. The upstream signal passes from the feeder fiber 16 to the backhaul fiber 30 via the WDM 44 U, a fiber segment 52 U, a gain element 48 U, a fiber segment 54 U and the WDM 44 D. We will assume for the purpose of this discussion that the gain elements are SOAs. The extenders also comprise respective failover units 58 A, 58 B. In one embodiment, each extender is implemented on a single printed circuit board and the two extender boards are mounted in a common chassis. Generally, the chassis will accommodate multiple pairs of extender boards. In another embodiment, one or more pairs of extenders are implemented on a single printed circuit board, Each extender includes current sources (not shown) for supplying bias current to the SOAs. The current sources are controlled by signals provided by the failover unit of the extender. Monitor photodetectors PD 1 , PD 2 , PD 3 and PD 4 are optically coupled to the fiber segments 52 D, 54 D, 52 U and 54 U respectively. In an illustrative embodiment, a photodetector may be coupled to its monitored fiber segment by utilizing a three-port passive optical coupler inserted in the path between the WDM and the SOA. The photodetectors generate current signals that depend on the optical signal power level in the respective fiber segments. Each failover unit may be implemented by a computer, as described in greater detail below, and includes adapters that receive the current signals generated by the photodetectors, convert the current signals to voltage form, digitize the voltage signals and supply the digitized voltage signals to the computer for processing. The computer determines whether an optical signal is present on the backhaul and feeder fibers, and is able to measure the gain of the gain elements. A failover unit may also be implemented in hard-wired logic devices instead of a computer. However, in the following discussion, the failover unit is implemented in a computer. The failover unit defines six operating states for the extender. Cold: The extender is new and unconfigured Stand-alone: Extender operation is stand-alone (unprotected) Working: The extender is the working extender of a protection pair, and is operational Protection: The extender is the protection extender of a protection pair, and is in warm standby condition. Standby: The extender is the working extender of a protection pair, but is in warm standby condition due to the working extender having declared a fault or failure Failover: The extender is the protection extender of a protection pair, but is operational due to the working extender having declared a fault or failure The computer maintains a database that stores the current operating state of the extender as a protection state variable. The Stand-alone operating state is not pertinent to the disclosed subject matter and will not be discussed further. The Cold, Working and Protection states are considered as the stable states of the system. These are stored in non-volatile memory, such as flash, and persist after power outage. During normal operation, the working extender is in the Working state and the protection extender is in warm Standby, with no drive current applied to its SOAs. Failover consists of turning off drive current to both SOAs in the old working extender, and turning on drive current to the SOAs in the old protection extender, in that order. Each failover unit implements a protocol state machine that defines ten states of the extender and the events that cause a transition from one state to another. The states of the protocol are as follows: P 0 —Cold P 1 —Normal operation—Working P 2 —Normal operation—Protection P 3 —Failover initiated P 4 —Failover ready P 5 —Failover not ready P 6 —Standby P 7 —Protection P 8 —Restoral initiated P 9 —Restoral ready In its initial condition after manufacture, an extender is not configured as either a protection extender or a working extender. The extender is in Cold condition (i.e. protocol state machine is in state P 0 and the extender is in the Cold operating state), and drive current is not applied to either SOA. A technician installs the extender board in the chassis and specifies the slot number of the partner (protection or working) extender in the same chassis and sets the protection state variable to Working or Protection, respectively. The extender transitions to either state P 1 or P 2 , respectively, for the Working and Protection extenders. If the extender transitions to state P 1 , the SOA drive current is set as configured, e.g., through calibration or operator commands. In addition to starting the protection state machine in a known and non-conflicting state, this also permits SOA operating mode and settings to be configured before starting the extenders. After the operational state of the extender has been set, its state is also stored in flash. In the event of a power outage, the operational state which has been stored in flash is restored after subsequent power-on, the extender transitions to either state P 1 or P 2 , and, if it transitions to state P 1 , the SOA drive current is set as configured. During normal operation, the working and protection extenders are in states P 1 and P 2 , respectively. When the working extender enters a downstream or upstream loss-of-signal (LOS) condition or an SOA failure condition (or multiple failure conditions), it sends an Initiate Failover message to the protection extender and enters state P 3 . When the protection extender receives an Initiate Failover message while in state P 2 or P 5 , it determines whether an upstream or downstream LOS condition is present. Note that there is no way to determine whether an SOA has failed unless bias current is applied. If neither LOS condition is present, the protection extender sends a Failover Ready message and enters state P 4 . If either LOS condition is present, the protection extender sends a Failover Not Ready message and enters state P 5 . When in any state other than P 2 or P 5 , the protection extender ignores an Initiate Failover message. When the working extender is in state P 3 and it receives a Failover Ready message, it turns off drive current to both SOAs, sends an Execute Failover message, sets the protection state variable to Standby, and enters state P 6 . In any state other than P 3 , the working extender ignores a Failover Ready message. When the working extender is in state P 3 and it receives a Failover Not Ready message, it returns to state P 2 . In any state other than P 3 , the working extender ignores a Failover Not Ready message. When the protection extender is in state P 4 and it receives an Execute Failover message, it turns on drive current to both SOAs (as determined by the configured operating mode and gain drive current or output power, respectively), and enters state P 7 . It also sets the protection state variable to Failover. In any state other than P 4 , the protection extender ignores an Execute Failover message. When the protection extender is in state P 5 , and both upstream and downstream LOS conditions are cleared, it reenters state P 2 . When the old working extender (i.e. the extender that was the working extender before failover) is in state P 6 and an external signal sets the protection state variable to Restore, if an upstream or downstream LOS condition exists, or if the cause of the failure was an SOA failure or over temperature condition, the old working extender remains in state P 6 and keeps the protection state variable in the Standby state. Otherwise, it sends an Initiate Restoral message to the protection extender, enters state P 8 and sets the protection state variable to Restore. When the protection extender receives an Initiate Restoral message while in state P 7 , it turns off drive current to both SOAs, sends an Execute Restoral message, sets the protection state variable to Protection and returns to state P 2 . In all other states, the protection extender ignores an Execute Restoral message. When the working extender receives an Execute Restoral message while in state P 8 , it turns on drive current to both SOAs (as determined by the configured operating mode and gain drive current or output power, respectively), sets the protection state variable to Working and enters state P 1 . In any state other than P 8 , the working extender ignores an Execute Restoral message. The failover units determine LOS conditions and SOA failure conditions by using the photodetector adapters to sample the time-averaged amplified photocurrent at the respective photodiodes. The presumption is that in normal operation the ones density of the signal is about 50% over the sampling period. This is more likely for the downstream than for the upstream, since the upstream is subject to quiet periods and non-productive polling of ONTs. Each failover unit has a preset downstream and upstream LOS soak time, i.e. a duration during which the failover unit does not respond to an input signal from a photodetector, in order to protect against initiating failover in response to a transient condition. Typically, the soak time will be of the order of tens of microseconds. A downstream Loss-of-Signal (LOS) condition is entered when downstream LOS detection is enabled (non-zero downstream LOS soak time), and the downstream received signal at PD 1 is below the configured downstream Receive Power Minimum Threshold during every sample over a period equal to the downstream LOS soak time. Note that the soak times for protection extenders should be somewhat shorter than those for working extenders, in order to ensure that the protection extender detects LOS from a common root cause before an unproductive failover, i.e. a failover that does not eliminate the fault condition. A downstream LOS condition is cleared when the downstream received signal at PD 1 is above the configured downstream Receive Power Minimum Threshold during 90% of samples over a period equal to the downstream LOS soak time. An upstream Loss-of-Signal (LOS) condition is entered when upstream LOS detection is enabled (non-zero upstream LOS soak time), the upstream received signal at PD 3 is below the configured upstream Receive Power Minimum Threshold during every sample over a period equal to the upstream LOS soak time, except that upstream LOS is not declared in the event of a downstream LOS or downstream SOA failure, since no ONT will transmit under either of those conditions. Note that the downstream LOS soak time will be shorter than the upstream LOS soak time. In particular, upstream LOS soak time will have to be longer than the longest quiet interval that can be established by the OLT during ranging. In addition, in the event of downstream LOS or amplifier failure, the longer upstream LOS soak time means the protection extender does not declare upstream LOS due solely to the ONTs being silent because of the downstream condition. However, this means that a fault in feeder plant will take longer to restore than a fault in the backhaul. Also note that the soak times for protection extenders should be somewhat shorter than those for working extenders, in order to ensure that the protection extender detects LOS from a common root cause before an unproductive failover. An upstream LOS condition is cleared when the upstream received signal at PD 3 is above the configured upstream Receive Power Minimum Threshold during 10% of samples over a period equal to the upstream LOS soak time. A downstream SOA failure condition is entered when drive current is applied, downstream LOS is not asserted, and downstream transmit signal at PD 2 is not greater than the downstream receive signal at PD 1 , for a period equal to the SOA failure soak time. It is also entered immediately when the downstream SOA is shut down due to an over temperature condition. An upstream SOA failure condition is entered when drive current is applied, upstream LOS is not asserted, and upstream transmit signal at PD 4 is not greater than the upstream receive signal at PD 3 , for a period equal to the SOA failure soak time. It is also entered immediately when the downstream upstream SOA is shut down due to an overtemperature condition. Fail-over occurs when an upstream or downstream LOS or SOA failure condition is entered in the working extender, and neither upstream nor downstream LOS condition is present at the protection extender; this avoids fail-over in the event that the failure is in an element (e.g., ONT power) which is not protected under this scheme, or in the unlikely event of multiple failures. Fail-over may also be initiated manually, e.g, at an element manager. Restoral after fail-over is typically initiated manually. In some, but not all, cases, it could also be initiated when valid signals upstream are received at the old working extender unit. In the case of the embodiment described with reference to FIG. 3 , in which each extender includes a failover unit, failover control is distributed and the method steps that are executed to accomplish failover control consist of first, determining, e.g., by manual configuration, which of the extender units is the working extender unit and which is the protection extender unit; second, enabling the working extender unit and disabling the protection extender unit; third, at the working extender unit monitoring the upstream and downstream signals and upstream and downstream transmit power; fourth, detecting a fault in either the backhaul fiber, the extender unit or the feeder fiber; fifth, sending a message from the working extender unit to the protection extender unit indicating that a failover is necessary; sixth, at the protection extender unit, determining whether a fault exists in the protection backhaul fiber or protection feeder fiber; seventh, if no such fault exists, sending a message to the working extender unit that the protection extender unit is prepared to failover; eighth, disabling the working extender unit; ninth, sending a message from the working extender unit to the protection extender unit indicating that the failover is in progress; and finally, enabling the protection extender unit. The failover protocol ensures that failover occurs in a break-before-make fashion, which is needed in order to protect receivers in the event that one SOA in the working extender fails. FIG. 4 illustrates a second embodiment of the disclosed subject matter, in which failover control is centralized. There is one failover unit for each working-protection pair of extender unit, the failover unit being coupled to both extender units. The manner in which the photodetectors are used to detect loss of signal conditions and SOA failure corresponds to that described with reference to FIG. 3 , but since a single failover unit controls the state of both extenders, there is no message passing between the extenders. In the case of centralized control, the method steps that are executed to accomplish failover control consist of first, determining, e.g., by manual configuration, which of the extender units is the working extender unit and which is the protection extender unit; second, enabling the working extender unit and disabling the protection extender unit; third, at the working extender unit monitoring the upstream and downstream signals and upstream and downstream transmit power; fourth, detecting a fault in either the backhaul fiber, the extender unit or the feeder fiber; fifth, at the protection extender unit, determining whether a fault exists in the protection backhaul fiber or protection feeder fiber; seventh, disabling the working extender unit; and, finally, enabling the protection extender unit. By localizing the problem of fault detection and coordination between the extenders, in both distributed control and centralized control, coordination is significantly simplified. A dedicated communications link is not needed between potentially distant OLTs, and delays in failover due to propagation through the link are eliminated. A fault that affects one direction of transmission in the extender can be detected. This property also helps in fault sectionalization, in that it can determine whether a fault is in the extender unit, in the feeder fiber or in the backhaul fiber. In an embodiment of the distributed control mechanism described with reference to FIG. 3 , each failover unit is implemented by a computer, as mentioned above. Referring to FIG. 5 , a suitable computer may comprise a processor 56 , random access memory 60 , read only memory 64 , and various interfaces organized in a generally conventional architecture and communicating via a bus. The interfaces include the adapters 66 that receive the current signals generated by the photodetectors and adapters 70 that provide output signals for selectively enabling and disabling the SOAs depending on the operating state of the extender. Although FIG. 3 illustrates a direct connection between the failover units of the respective extenders, in an embodiment of the disclosed subject matter the interfaces of each failover unit include a network interface device 68 that is connected to an Ethernet switch and the working and protection extenders communicate over a local area network that serves all the extenders that are installed in the chassis. The computer may operate in accordance with a program that is stored in a non-volatile computer readable medium, such as flash memory 70 , and is loaded into the random access memory 60 for execution. The program is composed of instructions such that when the computer receives signals from the photodetectors PD 1 , PD 2 , PD 3 , PD 4 by way of the adapters 66 , the computer utilizes suitable resources and functions to provide signals to the partner extender, to control the operating state of the extender and to maintain the database, in the manner described above. When the program causes a transition of an extender from one state to another, the program updates the value of the protection state variable stored in the database. In the event of a power outage, the database can be restored by reading the values from the non-volatile memory of the failover unit. The network infrastructure includes an element manager that may be located in the central office in which one or both of the OLTs are located, or may be located in a network operations center. The element manager may provide a human interface whereby an extender may be configured, various parameters of the extender may be summoned and viewed, events and alarms may be collected, correlated and displayed, and commands may be issued to the extender. The element manager may further communicate with and provide information to higher level managers. In addition, the housing that contains the chassis in which the extenders are installed also contains two local ONTs that are coupled to the working and protection backhaul fibers, respectively, in the extender. The local ONTs allow the extender units to communicate with the element manager by way of the backhaul fiber and the OLTs. If there are multiple working and protection pairs in the chassis, only one pair of local ONTs need be employed. The local ONTs are connected to the Ethernet switch. Therefore, the extenders are able to communicate with the element manager through the Ethernet switch and the local ONTs, and information regarding the current operating states of the extenders is available to the element manager. The element manager may maintain a database in which the values of the protection state variable for each extender are saved. Although embodiments have been described with reference to specific devices, such as WDMs and SOAs, it will be appreciated by those skilled in the art that in other embodiments other devices may be used. For example, in other embodiments optical circulators or another form of optical splitter technology may be used instead of the WDMs 34 , and as suggested above there are several technologies other than semiconductor optical amplifiers that may be used to implement the functionality of the gain elements 48 . Although the drawings illustrate fiber segments 52 , 54 coupling the WDMs to the gain elements and photodetectors coupled to the fiber segments for monitoring the optical power passing in the paths defined by the respective fiber segments, in other embodiments other techniques may be used to provide the optical coupling and permit the optical power passing in the respective paths to be monitored. Specifically, the photodetectors could be co-packaged with the gain elements, in which case there would be no fiber between the photodetectors and the respective gain elements; or an optical waveguide formed in a planar silicon/silica structure, for example by etching, may be used instead of a fiber, and in the latter case the three-port coupler may be formed in the same structure. It will be appreciated that the invention is not restricted to the particular embodiment that has been described, and that variations may be made therein without departing from the scope of the invention as defined in the appended claims, as interpreted in accordance with principles of prevailing law, including the doctrine of equivalents or any other principle that enlarges the enforceable scope of a claim beyond its literal scope. Unless the context indicates otherwise, a reference in a claim to the number of instances of an element, be it a reference to one instance or more than one instance, requires at least the stated number of instances of the element but is not intended to exclude from the scope of the claim a structure or method having more instances of that element than stated. The word “comprise” or a derivative thereof, when used in a claim, is used in a nonexclusive sense that is not intended to exclude the presence of other elements or steps in a claimed structure or method.

Extender apparatus for an optical network includes first and second extender units having an network-facing port for connection to a backhaul fiber and a subscriber-facing port for connection to a feeder fiber. Each extender unit includes a gain assembly and is operable selectively either in an enabled state, in which the gain assembly amplifies a signal received at either port of the extender unit and couples it to the other port of the extender unit, or in a disabled state, in which the gain assembly blocks coupling of a signal from either port of the extender unit to the other port of the extender unit. A failover unit is operable when the first extender unit is in the enabled state and the second extender unit is in the disabled state to detect occurrence of at least one fault condition in the first extender unit. The failover unit is responsive to the fault condition in the first extender unit to switch the first extender unit to the disabled state and the second extender unit to the enabled state.

THE FIELD OF THE INVENTION [0001] The present invention relates to medical device systems. Specifically, the invention pertains to a remote bi-directional communications with one or more programmers and medical units, or related controls that are associated with implantable medical devices (IMDs). More specifically, the invention relates to a system to aid in the initial implant and subsequent follow-up of IMDs. The invention utilizes a highly integrated system and method of bi-directional telecommunications between a web-based expert data center and a medical device, utilizing various types of network platforms and architecture, to inform patients and clinicians upon connection with the expert data center about recalls or alerts and recommend courses of action relating to the selection of programmable parameters and the course of treatment/follow-up of an IMD. BACKGROUND OF THE INVENTION [0002] A technology-based health care system that fully integrates the technical and social aspects of patient care and therapy should be able to flawlessly connect the client with care providers irrespective of separation distance or location of the participants. While clinicians will continue to treat patients in accordance with accepted modern medical practice, developments in communications technology are making it ever more possible to provide a seamless system of remote patient diagnostics, care and medical services in a time and place independent manner. [0003] Prior art methods of clinical services are generally limited to in-hospital operations. For example, if a physician needs to review the performance parameters of an implantable device in a patient, it is likely that the patient has to go to the clinic. Further, if the medical conditions of a patient with an implantable device warrant a continuous monitoring or adjustment of the device, the patient would have to stay in a hospital indefinitely. Such a continued treatment plan poses both economic and social problems. Under the exemplary scenario, as the segment of the population with implanted medical devices increases many more hospitals/clinics including service personnel will be needed to provide in-hospital service for the patients, thus escalating the cost of healthcare. Additionally the patients will be unduly restricted and inconvenienced by the need to either stay in the hospital or make very frequent visits to a clinic. [0004] Yet another condition of the prior art practice requires that a patient visit a clinic center for occasional retrieval of data from the implanted device to assess the operations of the device and gather patient history for both clinical and research purposes. Such data is acquired by having the patient in a hospital/clinic to down load the stored data from the implantable medical device. Depending on the frequency of data collection this procedure may pose serious difficulty and inconvenience for patients who live in rural areas or have limited mobility. Similarly, in the event a need arises to upgrade the software of an implantable medical device, the patient will be required to come into the clinic or hospital to have the upgrade installed. Further, in medical practice it is an industry-wide standard to keep an accurate record of past and contemporaneous procedures relating to an IMD uplink with, for example, a programmer. It is required that the report contains the identification of all the medical devices involved in any interactive procedure. Specifically, all peripheral and major devices that are used in down linking to the IMD need to be reported. Currently, such procedures are manually reported and require an operator or a medical person to diligently enter data during each procedure. One of the limitations of the reporting procedure is the fact that it is error prone and requires rechecking of the data to verify accuracy. Further, under present medical device databases, there is no well-defined interactive system that enables patients and clinicians to be aware of recalled or upgradeable units/components for IMDs. [0005] IMDs, programmers and related medical devices are distributed throughout the world. Further, the number of people with implanted medical devices has been increasing over the last few years. Thus, it is important to provide a broadcast system for recalled devices to ensure the safety of these globally distributed medical devices. Specifically, at current global distribution levels a web-enabled alert system of notification is a vital and necessary tool to promote safe therapy and clinical care worldwide. [0006] A further limitation of the prior art relates to the management of multiple medical devices in a single patient. Advances in modern patient therapy and treatment have made it possible to implant a number of devices in a patient. For example, IMDs such as a defibrillator or a pacer, a neural implant, a drug pump, a separate physiologic monitor and various other IMDs may be implanted in a single patient. To successfully manage the operations and assess the performance of each device in a patient with multi-implants requires a continuous update and monitoring of the devices. Further, it may be preferred to have an operable communication between the various implants to provide a coordinated clinical therapy to the patient. Thus, there is a need to monitor the IMDs including the programmer on a regular, if not a continuous, basis to ensure optimal patient care. [0007] Accordingly it is vital to have a programmer unit that would connect to a remote expert data center, a remote web-based data center or a remote data center, all these terms being alternate equivalents as used herein, to provide access to a database of recalled devices. More specifically, it is most desirable to provide globally distributed patients and their doctors information about recalled IMDs and those needing an upgrade consistent with standards set by the manufacturers of the IMDs. [0008] The proliferation of patients with multi-implant medical devices worldwide has made it imperative to provide remote services to the IMDs and timely clinical care to the patient. Frequent use of programmers to communicate with the IMDs and provide various remote services, consistent with co-pending applications titled “Apparatus and Method for Remote Troubleshooting, Maintenance and Upgrade of Implantable Device Systems,” filed on Oct. 26, 1999, U.S. patent application Ser. No. 09/426,741; “Tactile Feedback for Indicating Validity of Communication Link with an Implantable Medical Device,” filed Oct. 29, 1999, U.S. patent application Ser. No. 09/430,708; “Apparatus and Method for Automated Invoicing of Medical Device Systems,” filed Oct. 29, 1999, U.S. patent application Ser. No. 09/430,208; “Apparatus and Method for Remote Self-Identification of Components in Medical Device Systems,” filed Oct. 29, 1999, Ser. No. 09/429,956; “Apparatus and Method to Automate Remote Software Updates of Medical Device Systems,” filed Oct. 29, 1999, U.S. patent application Ser. No. 09/429,960; “Method and Apparatus to Secure Data Transfer From Medical Device Systems,” filed Nov. 2, 1999, U.S. patent application Ser. No. 09/431,881; “Implantable Medical Device Programming Apparatus Having An Auxiliary Component Storage Compartment,” filed Nov. 4, 1999, Ser. No. 09/433,477; “System of Notification of Recalled Components for a Medical Device,” filed Dec. 29, 1999, U.S. patent application Ser. No. 09/474,694; which are all incorporated by reference herein in their entirety, has become an important aspect of patient care. Thus, in light of the referenced disclosures, remote access to a data bank of recalled devices both consisting of Medtronic, Inc. and products made by other manufacturers, is a vital step in providing efficient therapy and clinical care to the patient. [0009] The prior art provides various types of remote sensing and communications with IMDs. Stranberg in U.S. Pat. No. 4,886,064, issued Dec. 12, 1989, for example, discloses one such system. In this disclosure, body activity sensors, such as temperature, motion, respiration and /or blood oxygen sensors, are positioned in a patient's body outside a pacer capsule. The sensors wirelessly transmit body activity signals, which are processed by circuitry in the heart pacer. The heart pacing functions are influenced by the processed signals. The signal transmission is a two-way network and allows the sensors to receive control signals for altering the sensor characteristics. [0010] One of the many limitations of Stranberg is the fact that although there is corporeal two-way communications between the implantable medical devices, and the functional response of the heart pacer is processed in the pacer after collecting input from the other sensors, the processor is not remotely programmable. Specifically, the system does not lend itself to web-based communications because the processor/programmer is internally located in the patient forming an integral part of the heart pacer. [0011] Yet another prior art reference provides a multi-module medication delivery system as disclosed by Fischell in U.S. Pat. No. 4,494,950 issued Jan. 22, 1985. The disclosure relates to a system consisting a multiplicity of separate modules that collectively perform a useful biomedical purpose. The modules communicate with each other without the use of interconnecting wires. All the modules may be installed intracorporeal or mounted extracorporeal to the patient. In the alternate, some modules may be intracorporeal with others being extracorporeal. Signals are sent from one module to the other by electromagnetic waves. Physiologic sensor measurements sent from a first module cause a second module to perform some function in a closed loop manner. One extracorporeal module can provide electrical power to an intracorporeal module to operate a data transfer unit for transferring data to the external module. [0012] The Fischell disclosure provides modular communication and cooperation between various medication delivery systems. However, the disclosure does not provide an external programmer with remote sensing, remote data management and maintenance of the modules. Further, the system does neither teach nor disclose the notification/recommendation scheme contemplated by the present invention. [0013] An additional example of prior art practice includes a packet-based telemedicine system for communicating information between central monitoring stations and a remote patient monitoring station disclosed in Peifer, WO 99/14882 published Mar. 25, 1999. The disclosure relates to a packet-based telemedicine system for communicating video, voice and medical data between a central monitoring station and a patient that is remotely located with respect to the central monitoring station. The patient monitoring station obtains digital video, voice and medical measurement data from a patient and encapsulates the data in packets and sends the packets over a network to the central monitoring station. Since the information is encapsulated in packets, the information can be sent over multiple types or combination of network architectures, including a community access television (CATV) network, the public switched telephone network (PSTN), the integrated services digital network (ISDN), the Internet, a local area network (LAN), a wide area network (WAN), over a wireless communications network, or over asynchronous transfer mode (ATM) network. A separate transmission code is not required for each different type of transmission media. [0014] One of the advantages of the Pfeifer invention is that it enables data of various forms to be formatted in a single packet irrespective of the origin or medium of transmission. However, the data transfer system lacks the capability to remotely debug or optimize the performance parameters of the medical interface device or the programmer. Further, Pfeifer does not disclose a method or structure by which the devices at the patient monitoring station may be remotely optimized for patient safety or benefit. [0015] In a related art, Thompson discloses a patient tracking system in U.S. Pat. No. 6,083,248 entitled “World-wide Patient Location and Data Telemetry System For Implantable Medical Devices ”, issued on Jul. 4, 2000, which is incorporated by reference herein in its entirety. The '248 patent provides additional features for patient tracking in a mobile environment worldwide via the GPS system. However, the notification of recalled parts and upgradeable units advanced by the present invention are not within the purview of the Thompson disclosure because there is no teaching of a web-based environment in which a programmer or an interface medical unit (IMU) is used to transfer IMD data for monitoring and to alert the patient and clinician about safety and function improvements to the IMD units. [0016] Yet in another related art, Ferek-Petric discloses a system for communication with a medical device in a co-pending application, U.S. patent application Ser. No. 09/348,506, “System for Remote Communication with a Medical Device,” filed Jul. 7, 1999, which is incorporated by reference herein in its entirety. The disclosure relates to a system that enables remote communications with a medical device, such as a programmer. Particularly, the system enables remote communications to inform device experts about programmer status and problems, the experts will then provide guidance and support remotely to service personnel or operators located at the programmer. The system may include a medical device adapted to be implanted into a patient; a server PC (SPC) communicating with the medical device; the server PC having means for receiving data transmitted across a dispersed data communication pathway, such as the Internet; and a client PC having means for receiving data transmitted across a dispersed communications pathway from the SPC. In certain configurations the SPC may have means for transmitting data across a dispersed data communication pathway (Internet) along a first channel and a second channel; and the client PC may have means for receiving data across a dispersed communication pathway from the SPC along a first channel and a second channel. [0017] One of the significant teachings of Ferek-Petric's disclosure, in the context of the present invention, includes the implementation of communication systems, associated with IMDs that are compatible with the Internet. Specifically the disclosure advances the art of remote communications between a medical device, such as a programmer, and experts located at a remote location using the Internet. As indicated hereinabove, the communications scheme is structured to primarily alert remote experts to existing or impending problems with the programming device so that prudent action, such as early maintenance or other remedial steps, may be timely exercised. Further, because of the early warning or advance knowledge of the problem, the remote expert would be well informed to provide remote advice or guidance to service personnel or operators at the programmer. [0018] While Ferek-Petric's invention advances the art in communications systems relating to interacting with a programmer via a communication medium such as the Internet, the system does neither propose nor suggest the notification/recommendation system advanced by the present invention. [0019] In yet another related art Knapp discloses a medical information transponder implant and tracking system in U.S. Pat. No. 5,855,609 issued on Jan. 5, 1999. The disclosure relates to a passive electrical transponder directly transplanted in a patient's underarm area. Medical devices may also carry transponders to identify them for use with the tracking system of the invention. An identification code is accessed with an electromagnetic hand held reader, which is brought into proximity of the transponder. The medical information may itself be directly encoded into the transponder, or a code used which is then keyed to a corresponding data entry in a data bank or computerized database accessible over telecommunication lines. Accordingly, medical information may be reliably and confidentially recorded and accessed confidentially. [0020] While the Knapp disclosure advances the art of medical information collection for both short term and extended time periods for analysis to generate recall notices and to provide generalized health services, it fails far short of the advances brought about by the present invention. Specifically the present invention provides a statistical survival probability projection based upon the implanted base of IMD units to inform patients and their caregivers to allow optimization of IMD safety and function and improve patient benefits of the therapy provided on a real time basis. More specifically the present invention utilizes a programmer or equivalent interface unit that monitors one or more implanted devices on a chronic basis. The interface unit also transfers the information thus collected to a preferably web enabled expert data center for evaluation, analysis and follow-up. In the process, the implanted devices in the patient are checked against a list of measured parameter limits and projections from a remote database. In the event one or more of the devices measured characteristics are found to be out of specification, the clinician and the patient are notified via a preferably web-enabled communication network. [0021] In yet another related art, in U.S. Pat. No. 5,391,193, Thompson discloses a method and apparatus for estimating the remaining capacity of a lithium-iodine battery through the nomographic analysis of two or more measurements of battery impedance. In a preferred embodiment, a pacemaker or other implantable medical device is provided with circuitry for periodically measuring the internal impedance of its battery. Each measurement of impedance is stored along with an indication of when such measurement was made. Nomographic analysis, based upon the rated capacity of the battery and the expected internal impedance at various stages of depletion, allows for two or more time-stamped impedance measurements to serve as the basis for an extrapolation to estimate the remaining service life of the implantable medical device. Nomographic analysis may be performed by circuitry contained in the implanted device itself; in the alternative, periodic impedance measurements may be communicated to external processing circuitry via a telemetry channel. This system does not use a remote integrated database of statistical survival probability projections to aid in the management of patient safety and IMD longevity actions. [0022] In yet another related art, in U.S. Pat. No.4,979,507, Heinz discloses a system that has as an objective the universal matching of individual patient-pacemaker-implant electrode interface conditions to follow dynamic changes occurring in use, from pacemaker to pacemaker and from patient to patient to control the pacing pulse energy in operation most efficiently to prolong battery life. Information from the implanted stimulation electrode is analyzed to discriminate the energy level of pulses effective and ineffective to stimulate a heartbeat for at least two different stimulation pulse characteristics. This analyzed information is automatically processed in logic circuits to conform to the requirements of particular pacemaker adjustments to develop an optimized energy pacing pulse with adequate safety margin. Programming and logic equipment can be in the pacemaker, but additional energy saving with those calculations takes place when it is external to the pacemaker and bi-directional communication of information takes place with the pacemaker. Periodic automatic programming can take place in implanted pacemaker installations for continuous long term monitoring and control to obtain the optimum battery life and adequate safety standards. This system does not use a remote integrated database of statistical survival probability projections to aid in the management of patient safety and IMD longevity actions. [0023] In yet another related art, in U.S. Pat. No. 5,620,474, Koopman describes a programmable pacing system and method, the system having the capability for providing an indication of recommended replacement time (RRT) as well as a prior warning of six months to RRT. RRT is determined by storing a value in the pacemaker corresponding to battery impedance at RRT, continuously periodically measuring battery impedance, and comparing the measured value with the stored RRT value. Whenever the pacemaker is reprogrammed to different operating conditions which affect RRT, or there is a significant change in load lead resistance, a new value of RRT impedance is calculated based upon a selected formula corresponding to the reprogrammed set of operating conditions, and stored in the pacemaker. At the same time, an aging value of impedance is re-calculated to provide a six-month warning before RRT, and likewise stored in the pacemaker. This system does not use a remote integrated database of statistical survival probability projections to aid in the management of patient safety and IMD longevity actions. [0024] In yet another related art, in U.S. Pat. No. 5,309,919, Snell describes a method and system for monitoring the behavior of an implanted pacemaker counts (records) the number of times that a given internal event or state change of the pacemaker occurs, and also determines the rate at which each event or state change thus counted occurs. The event counts and their associated rate are stored (recorded) in appropriate memory circuits housed within the pacemaker device. At an appropriate time, the stored event count and rate data are downloaded to an external programming device. The external programming device processes the event count and rate data, and displays a distribution of the event count data as a function of its rate of occurrence, as well as other statistical information derived therefrom. The displayed information, and its associated statistical information, allows a baseline recording to be made that establishes the implanted pacemaker's behavior for a given patient under known conditions. Such baseline recording of event counts in combination with the associated rate of occurrence of such event counts provides significant insight into the past behavior of the pacemaker as implanted in a particular patient. The past behavior of the pacemaker, in turn, may then be used to predict with a high degree of accuracy the future behavior of the pacemaker. This system does not use a remote integrated database of statistical survival probability projections to aid in the management of patient safety and IMD longevity actions. [0025] Accordingly, it would be desirable to provide a system in which one or more implanted devices could uplink to a remote expert data center via an interface medical unit such as a programmer to access a patient and device information database to identify devices or components out of specification and notify the clinician and/or patient as apparent. Yet another desirable advantage would be to provide a system to implement the use of remote expert systems to optimally manage IMDs on a real-time basis. A further desirable advantage would be to provide a communications scheme that is compatible with various communications media, to promote a fast uplink of a programmer to remote expert systems and specialized data resources to chronically monitor IMDs and provide an uninterrupted management of patient therapy and clinical care. Yet another desirable advantage would be to provide a high speed communications scheme to enable the transmission of high fidelity sound, video and data to advance and implement efficient remote data management of a clinical/therapy system via a programmer or an interface medical unit thereby enhancing patient clinical care. Yet a further desirable advantage would be to remotely import a software-based patient and device information for use by local clinicians/operators/technicians using programmers for IMDs distributed throughout the world. Preferably, a remote web-based expert data center would direct, update, command and control a software-based information system worldwide to keep an interconnected scheme in which, among other services, information about improving patient safety and benefit from IMDs are kept for alerting patients or care givers, as needed. As discussed herein below, the present invention provides these and other desirable advantages. SUMMARY OF THE INVENTION [0026] The present invention generally relates to a communications scheme in which a remote web-based expert data center interacts with a patient having one or more implantable medical devices (IMDs) via an associated external medical device, preferably a programmer or an interface medical unit (IMU), located in close proximity to the IMDs. Some of the most significant elements of the invention include the use of various communications media between the remote web-based expert data center and the programmer to remotely exchange clinically significant information and ultimately effect real-time parametric and operational changes as needed. [0027] In the context of the present invention, one of the many aspects of the invention includes a real-time access of a programmer or an IMD to a remote web-based expert data center, via a communication network, which includes the Internet. The operative structure of the invention includes the remote web-based expert data center, in which an expert system is maintained, having a bi-directional real-time data, sound and video communications with the programmer via a broad range of communication link systems. The programmer is in turn in telemetric communications with the IMDs such that the IMDs may uplink to the programmer or the programmer may down link to the IMDs, as needed. [0028] In a further context of the invention, a programmer is remotely monitored, assessed and upgraded as needed by importing expert systems from a remote expert data center via a wireless or equivalent communications system. The operational and functional software of the embedded systems in the programmer may be remotely adjusted, upgraded or changed to ultimately be implemented in the IMDs as needed by down linking from the programmer to the IMDs. [0029] Yet another context of the invention includes a communications scheme that provides a highly integrated and efficient method and structure of clinical information management in which various networks such as Community access Television, Local area Network (LAN), a wide area network (WAN) Integrated Services Digital Network (ISDN), the Public Switched telephone Network (PSTN), the Internet, a wireless network, an asynchronous transfer mode (ATM) network, a laser wave network, satellite, mobile and other similar networks are implemented to transfer voice, data and video between the remote data center and a programmer. In the preferred embodiment, wireless communications systems, a modem and laser wave systems are illustrated as examples only and should be viewed without limiting the invention to these types of communications alone. Further, in the interest of simplicity, the applicants refer to the various communications system, in relevant parts, as a communication system. However, it should be noted that the communication systems, in the context of this invention, are interchangeable and may relate to various schemes of cable, fiber optics, microwave, radio, laser and similar communications or any practical combinations thereof. [0030] Yet one of the other distinguishing features of the invention includes the use a highly flexible and adaptable communications scheme to promote continuous and real-time communications between a remote expert data center and a programmer associated with a plurality of IMDs. The IMDs are structured to share information intracorporeally and may interact with the programmer or IMU, as a unit. Specifically, the IMDs either jointly or severally can be interrogated to implement or extract clinical information as required. In other words, all of the IMDs may be accessed via one IMD or, in the alternate, each one of the IMDs may be accessed individually. The information collected in this manner may be transferred to the programmer by up linking the IMDs as needed. [0031] Further, the present invention provides significant distinctions over the prior art by enabling remote troubleshooting, maintenance and recommendations for patient safety and program enhancements to the IMDs. The communications scheme enables remote debugging, projections and analysis on the programmer. In the event a component defect or end of life projection is nearing, the system is able to check whether a ‘remote-fix’ and/or programming change is possible. If not, the system broadcasts an alert to clinician thus attending to the problem on a real-time basis. In the execution of this function the communications scheme of the present invention performs, inter alia, a review of usage logs, error logs, power and battery status, database integrity and the projected mean time to failure status of all the significant and relevant components. Further, patient history, performance parameter integrity from the remote expert data center and the IMDs' diagnostic data are mined from the programmer's database and analyzed by an analyzer resident in the programmer. [0032] The invention provides significant compatibility and scalability to other web-based applications such as telemedicine and emerging web-based technologies such as tele-immersion. For example, the system may be adapted to webtop applications in which a IMU may be used to uplink the patient to a remote data center for non-critical information exchange between the IMDs and the remote expert data center. In these and other web-based similar applications the data collected, in the manner and substance of the present invention, may be used as a preliminary screening to identify the need for further intervention using the advanced web technologies. [0033] More significantly, the invention provides a system and method to remotely alert the patients/clinician if there are out of specification, or about to be out of specification, devices or components of an implantable medical device. Further, the invention enables the patient/clinician to be aware of IMDs requiring increased follow-up frequency and programming changes. Furthermore, the invention enables the patient/clinician to access web sites tailored to provide pertinent information regarding the patient's IMDs and general clinical profile. BRIEF DESCRIPTION OF THE DRAWINGS [0034] The present invention will be appreciated as the same becomes better understood by reference to the following detailed description of the preferred embodiment of the invention when considered in connection with the accompanying drawings, in which like numbered reference numbers designate like parts throughout the figures thereof, and wherein: [0035] [0035]FIG. 1 is a simplified schematic diagram of major uplink and downlink telemetry communications between a remote clinical station, a programmer and a plurality of implantable medical devices (IMDs); [0036] [0036]FIG. 2 is a block diagram representing the major components of an IMD; [0037] [0037]FIG. 3A is a block diagram presenting the major components of a programmer or IMU; [0038] [0038]FIG. 3B is a block diagram representing a laser transceiver for high-speed transmission of voice, video and other data; [0039] [0039]FIG. 4 is a block diagram illustrating the organizational structure of the communication system between the various functional units and the remote expert data center in accordance with the present invention; [0040] [0040]FIG. 5 is a logic flow chart representing high-level steps of the software program in accordance with the present invention; [0041] [0041]FIG. 6 is a logic flow chart representing the detailed steps of the software program in accordance with the present invention; [0042] [0042]FIG. 7 is a lead survivability probability projection in accordance with the present invention; and [0043] [0043]FIG. 8 is a pacemaker survivability probability projection in accordance with the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS [0044] [0044]FIG. 1 is a simplified schematic of the major components of the present invention. Specifically, a bi-directional wireless communications system between programmer 20 , interface medical unit (IMU) 20 ′ and a number of implantable medical devices (IMDS) represented by IMD 10 , IMD 10 ′ and IMD 10 ″ is shown. The IMDs are implanted in patient 12 beneath the skin or muscle. The IMDs are electrically coupled to electrodes 18 , 30 , and 36 respectively in a manner known in the art. IMD 10 contains a microprocessor for timing, sensing and pacing functions consistent with preset programmed functions. Similarly, IMDs 10 ′ and 10 ″ are microprocessor-based to provide timing and sensing functions to execute the clinical functions for which they are employed. For example, IMD 10 ′ could provide neural stimulation to the brain via electrode 30 and IMD 10 ″ may function as a drug delivery system that is controlled by electrode 36 . The various functions of the IMDs are coordinated using wireless telemetry. Wireless links 42 , 44 and 46 jointly and severally couple IMDs 10 , 10 ′ and 10 ″ such that programmer 20 may transmit commands or data to any or all the of IMDs via one of telemetry antennas 28 , 32 and 38 . This structure provides a highly flexible and economical wireless communications system between the IMDs. Further, the structure provides a redundant communications system, which enables access to any one of a multiplicity of IMDs in the event of a malfunction of one or two of antennas 28 , 32 and 38 . [0045] Programming commands or data are transmitted from programmer 20 to IMDs 10 , 10 ′ and 10 ″ via external RF telemetry antenna 24 . Telemetry antenna 24 may be an RF head or equivalent. Antenna 24 may be located on programmer 20 externally on the case or housing. Telemetry antenna 24 is generally telescoping and may be adjustable on the case of programmer 20 . Both programmer 20 and IMU 20 ′ may be placed a few feet away from patient 12 and would still be within range to wirelessly communicate with telemetry antennas 28 , 32 and 38 . [0046] The uplink to remote web-based expert data center 62 , hereinafter referred to as, interchangeably, “data center 62 ”, “expert data center 62 ” or “web-based data center 62 ” without limitations, is accomplished through programmer 20 or IMU 20 ′. Accordingly programmer 20 and IMU 20 ′ function as an interface between IMDs 10 , 10 ′ and 10 ″ and data center 62 . One of the many distinguishing elements of the present invention includes the use of various scalable, reliable and high-speed wireless communication systems to bi-directionally transmit high fidelity digital/analog data between programmer 20 and data center 62 . [0047] There are a variety of wireless mediums through which data communications could be established between programmer 20 or IMU 20 ′ and data center 62 . The communications link between Programmer 20 or IMU 20 ′ and data center 62 could be modem 60 , which is connected to programmer 20 on one side at line 63 and data center 62 at line 64 on the other side. In this case, data is transferred from data center 62 to programmer 20 via modem 60 . Alternate data transmission systems include, without limitations, stationary microwave and/or RF antennas 48 being wirelessly connected to programmer 20 via tunable frequency wave delineated by line 50 . Antenna 48 is in communications with data center 62 via wireless link 65 . Similarly, IMU 20 ′, mobile vehicle 52 and satellite 56 are in communications with data center 62 via wireless link 65 . Further, mobile system 52 and satellite 56 are in wireless communications with programmer 20 or IMU 20 ′ via tunable frequency waves 54 and 58 , respectively. [0048] In the preferred embodiment a Telnet system is used to wirelessly access data center 62 . Telnet emulates a client/server model and requires that the client run a dedicated software to access data center 62 . The Telnet scheme envisioned for use with the present invention includes various operating systems including UNIX, Macintosh, and all versions of Windows. [0049] Functionally, an operator at programmer 20 , an operator at data center 62 or a clinician/physician at center 66 would initiate remote contact. Programmer 20 is down linkable to IMDs via link antennas 28 , 32 and 38 to enable data reception and transmission. For example, an operator or a clinician at data center 62 may downlink to programmer 20 to perform a routine or a scheduled evaluation of programmer 20 . In this case the wireless communication is made via wireless link 65 . If a downlink is required from programmer 20 to IMD 10 for example, the downlink is effected using telemetry antenna 22 . In the alternate, if an uplink is initiated from patient 12 to programmer 20 the uplink is executed via wireless link 26 . As discussed herein below, each antenna from the IMDs can be used to uplink all or one of the IMDs to programmer 20 . For example, IMD 10 ″ which relates to neural implant 30 can be implemented to up-link, via wireless antenna 34 or wireless antenna 34 ′, any one, two or more IMDs to programmer 20 . Preferably Bluetooth chips, adopted to function within the body to outside the body and also adopted to provide low current drain, are embedded in order to provide wireless and seamless connections 42 , 44 and 46 between IMDs 10 , 10 ′ and 10 ″. The communication scheme is designed to be broadband compatible and capable of simultaneously supporting multiple information sets and architecture, transmitting at relatively high speed, to provide data, sound and video services on demand. [0050] [0050]FIG. 2 illustrates typical components of an IMD, such as those contemplated by the present invention. Specifically, major operative structures common to all IMDs 10 , 10 ′ and 10 ″ are represented in a generic format. In the interest of brevity, IMD 10 relative to FIG. 2 refers to all the other IMDs. Accordingly, IMD 10 is implanted in patient 12 beneath the patient's skin or muscle and is electrically coupled to heart 16 of patient 12 through pace/sense electrodes and lead conductor(s) of at least one cardiac pacing lead 18 in a manner known in the art. IMD 10 contains timing control 72 including operating system that may employ microprocessor 74 or a digital state machine for timing, sensing and pacing functions in accordance with a programmed operating mode. IMD 10 also contains sense amplifiers for detecting cardiac signals, patient activity sensors or other physiologic sensors for sensing the need for cardiac output, and pulse generating output circuits for delivering pacing pulses to at least one heart chamber of heart 16 under control of the operating system in a manner well known in the prior art. The operating system includes memory registers or RAM/ROM 76 for storing a variety of programmed-in operating mode and parameter values that are used by the operating system. The memory registers or RAM/ROM 76 may also be used for storing data compiled from sensed cardiac activity and/or relating to device operating history or sensed physiologic parameters for telemetry out on receipt of a retrieval or interrogation instruction. All of these functions and operations are well known in the art, and many are generally employed to store operating commands and data for controlling device operation and for later retrieval to diagnose device function or patient condition. [0051] Programming commands or data are transmitted between IMD 10 RF telemetry antenna 28 , for example, and an external RF telemetry antenna 24 associated with programmer 20 . In this case, it is not necessary that the external RF telemetry antenna 24 be contained in a programmer RF head so that it can be located close to the patient's skin overlying IMD 10 . Instead, the external RF telemetry antenna 24 can be located on the case of programmer 20 . It should be noted that programmer 20 can be located some distance away from patient 12 and is locally placed proximate to the IMDs such that the communication between IMDs 10 , 10 ′ and 10 ″ and programmer 20 is telemetric. For example, programmer 20 and external RF telemetry antenna 24 may be on a stand a few meters or so away from patient 12 . Moreover, patient 12 may be active and could be exercising on a treadmill or the like during an uplink telemetry interrogation of real-time ECG or other physiologic parameters. Programmer 20 may also be designed to universally program existing IMDs that employ RF telemetry antennas of the prior art and therefore also have a conventional programmer RF head and associated software for selective use therewith. [0052] In an uplink communication between IMD 10 and programmer 20 , for example, telemetry transmission 22 is activated to operate as a transmitter and external RF telemetry antenna 24 operates as a telemetry receiver. In this manner data and information may be transmitted from IMD 10 to programmer 20 . In the alternate, IMD 10 RF telemetry antenna 26 operates as a telemetry receiver antenna to downlink data and information from programmer 20 . Both RF telemetry antennas 22 and 26 are coupled to a transceiver comprising a transmitter and a receiver. [0053] [0053]FIG. 3A is a simplified circuit block diagram of major functional components of programmer 20 . The external RF telemetry antenna 24 on programmer 20 is coupled to a telemetry transceiver 86 and antenna driver circuit board including a telemetry transmitter and telemetry receiver 34 . The telemetry transmitter and telemetry receiver are coupled to control circuitry and registers operated under the control of microcomputer 80 . Similarly, within IMD 10 , for example, the RF telemetry antenna 26 is coupled to a telemetry transceiver comprising a telemetry transmitter and telemetry receiver. The telemetry transmitter and telemetry receiver in IMD 10 are coupled to control circuitry and registers operated under the control of microcomputer 74 . [0054] Further referring to FIG. 3A, programmer 20 is a personal computer type, microprocessor-based device incorporating a central processing unit, which may be, for example, an Intel Pentium microprocessor or the like. A system bus interconnects CPU 80 with a hard disk drive, storing operational programs and data, and with a graphics circuit and an interface controller module. A floppy disk drive or a CD ROM drive is also coupled to the bus and is accessible via a disk insertion slot within the housing of programmer 20 . Programmer 20 further comprises an interface module, which includes a digital circuit, a non-isolated analog circuit, and an isolated analog circuit. The digital circuit enables the interface module to communicate with interface controller module. Operation of the programmer in accordance with the present invention is controlled by microprocessor 80 . [0055] In order for the physician or other caregiver or operator to communicate with the programmer 20 , a keyboard or input 82 coupled to CPU 80 is optionally provided. However the primary communications mode may be through graphics display screen of the well-known “touch sensitive” type controlled by a graphics circuit. A user of programmer 20 may interact therewith through the use of a stylus, also coupled to a graphics circuit, which is used to point to various locations on screen or display 84 which display menu choices for selection by the user or an alphanumeric keyboard for entering text or numbers and other symbols. Various touch-screen assemblies are known and commercially available. Display 84 and or the keyboard comprise means for entering command signals from the operator to initiate transmissions of downlink or uplink telemetry and to initiate and control telemetry sessions once a telemetry link with data center 62 or an implanted device has been established. Display screen 84 is also used to display patient related data and menu choices and data entry fields used in entering the data in accordance with the present invention as described below. Display screen 84 also displays a variety of screens of telemetered out data or real-time data. Display screen 84 may also display uplinked event signals as they are received and thereby serve as a means for enabling the operator to timely review link-history and status. [0056] Programmer 20 further comprises an interface module, which includes digital circuit, non-isolated analog circuit, and isolated analog circuit. The digital circuit enables the interface module to communicate with the interface controller module. As indicated hereinabove, the operation of programmer 20 , in accordance with the present invention, is controlled by microprocessor 80 . Programmer 20 is preferably of the type that is disclosed in U.S. Pat. No. 5,345,362 to Winkler, which is incorporated by reference herein in its entirety. [0057] Display screen 84 may also display up-linked event signals when received and thereby serve as a means for enabling the operator of programmer 20 to correlate the receipt of uplink telemetry from an implanted device with the application of a response-provoking action to the patient's body as needed. Programmer 20 is also provided with a strip chart printer or the like coupled to interface controller module so that a hard copy of a patient's ECG, EGM, marker channel of graphics displayed on the display screen can be generated. [0058] As will be appreciated by those of ordinary skill in the art, it is often desirable to provide a means for programmer 20 to adapt its mode of operation depending upon the type or generation of implanted medical device to be programmed and to be compliant with the wireless communications system through which data and information is transmitted between programmer 20 and data center 62 . [0059] [0059]FIG. 3B is an illustration of the major components of Wave unit 90 utilizing laser technologies such as for example the WaveStar Optic Air Unit, manufactured by Lucent Technologies or equivalent. This embodiment may be implemented for large data transfer at high speed in applications involving several programmers. The unit includes laser 92 , transceiver 94 and amplifier 96 . A first wave unit 90 is installed at data center 62 and a second unit 90 ′ is located proximate to programmer 20 or IMU 20 ′. Data transmission between remote data center 62 and programmer unit 20 is executed via wave units 90 . Typically, the first wave unit 90 accepts data and splits it into unique wavelength for transmission. The second wave unit 90 ′ recomposes the data back to its original form. [0060] [0060]FIG. 4 is a simplified block diagram illustrating the principal systems of the invention. The Remote expert system or data center 62 includes patient data 100 . Further, data center 62 includes device database 102 . Database 102 further includes recalled/up-gradable devices database 104 , other device information 106 and statistical projected survival database for all of Medtronic's™ products 108 . Under normal operations, an uplink is initiated by the clinician/physician at center 66 . In the alternate, the clinician/physician center may be one and the same as remote center 62 . Remote center 62 is preferably web-enabled and includes high speed computer resources and software (not shown) adapted for data storage, analysis and management to provide rapid data exchange between programmer 20 or IMU 20 ′ and clinician/physician center 66 . The various remote centers including data center 62 and clinician center 66 are connected via wireless or equivalent communication channels to provide real-time data, sound and video exchange between programmer 20 , IMU 20 ′, IMDs 10 , 10 ′ and 10 ″. In the context of the present invention, when either programmer 20 or IMU 20 ′ is remotely linked via link A or E, respectively, to data center 62 , access is made to patient database 100 . Information on IMDs 10 , l 0 ′ and 10 ″ is transmitted through up-link connection B or C to either programmer 20 or IMU 20 ′, respectively. The information is compared with patient database 100 at remote data center 62 . Patient database then searches to match the information from IMDs 10 , 10 ′ and 10 ″ with recalled/up-gradable devices database 104 which may be specific to the products made by several manufacturers. Further, the information is also compared with the statistical information database 108 such as, for example, device projected longevity estimates, lead impedance measurements, measured pacing and sensing thresholds, and long-term clinical data. Thus, in addition to providing the various clinical and therapeutic management functions based on the communications between the patient station, remote data center 62 and clinician/physician center 66 , the invention enables the implementation of a proactive alert system to inform patients of recalled, obsolete or up-gradable units needing replacement, and optimization of therapy, safety and benefit for the patient. [0061] Referring to FIG. 5, a high-level software logic operating the alert system of the present invention is disclosed. Specifically, the system is initiated under logic step 110 . The logic proceeds to step 112 where access to remote data center is allowed. Thereafter, the user is authenticated under logic step 114 . If the user is not certified, the logic proceeds to end at step 115 . If the user is granted access, the logic advances to step 116 where the database in remote center 62 is accessed. Subsequently, the user is served a set of menus displaying a selection of a file or files for access. The user then selects a file or files under logic step 118 . The logic proceeds to decision step 120 to check if any file(s) is selected. If no file is selected, the sequence is ended under step 119 and/or the program enters a subroutine where the user is prompted to select a file(s) before further access to subsequent logic steps is allowed. In the event a database for a certain file(s) is selected the program proceeds to decision step 122 . If the selection is not to access database 104 the logic proceeds to step 123 where the access to the file is ended. If the choice is to access database 104 , the logic proceeds to decision block 124 where the user's IMDs or the information relating to the IMDs is located in database 104 . If the device in question is not found to be in the list of recalled or up-gradable devices, the logic proceeds to step 125 and the program is terminated. In the alternate, if the device is found to be in the list of recalled or up-gradable devices, relating to products made by manufacturers other than Medtronic™, an alert flag is set under logic step 126 . Subsequently, an E-mail alert or equivalent is sent to the clinician or the operator responsible for managing the patient's data under step 128 and the session ends at step 130 . [0062] If the user elects to access patient data files, the program logic proceeds to decision step 132 . The system confirms if the user wants to access the patient data files 100 . In the event the user does not want to proceed with this choice, the program is terminated at step 133 . However, if the user wants to review or access patient data 100 , the program logic advances to logic step 134 and searches the file automatically to match it with the IMDs and related data specific to the user or the patient. Subsequently, the logic proceeds to decision block 136 to check if a match is found. If no match is located the program ends at step 135 . If a match is found, however, the program advances to step 138 to display the results of the match. The results of the match may include specific patient information including the IMDs and pertinent clinical and therapy information. [0063] Yet another alternate choice could be for the user to access other device information or general Medtronic™ device information file 106 under decision block 142 . The program logic confirms if this is the choice or otherwise it will be terminated under step 143 . After the selection is confirmed, however, the program logic proceeds to step 144 where the Medtronic™ device information file 106 is opened. Thereafter, the patient's IMDs are compared with resident data and information under logic step 146 . Subsequently, relevant information is displayed, as required by the user, under logic step 148 . The program logic proceeds to decision block 149 where the need for further information is checked under logic step 150 . If the user indicates not to proceed any further, the program is terminated at step 149 . If the user elects to get further information, the system displays the additional information under logic step 152 and the session ends at step 154 . [0064] Yet another selection could be the user may elect to review or access database 108 relating to the optimization of therapy, estimate remaining longevity, suggest follow-up frequency changes, and verify device functionality. If this is not the user's selection the program is terminated at logic step 157 . If however, the user requests to access database 108 , the program logic proceeds to decision step 158 to check if the user's or patient's IMDs match the list of Medtronic™ products with available function tests and projections. If there is no match the program is terminated at logic step 159 . In the alternate if a match is found, a flag is displayed to alert the user under logic step 160 . The clinician is then notified under logic step 162 to make sure that a clinical follow-up is undertaken. Further, the program posts a recommended course of action under logic step 164 . The program is then terminated under logic step 166 . [0065] In this manner, a patient is enabled to access patient data 100 , recalled device/upgrade file 104 , general device/ other device information file 106 and Medtronic™ statistical database 108 files remotely via programmer 20 or IMU 20 ′. Specifically, the invention enables the patient or manager of IMDs 10 , 10 ′ and 10 ″ to access remote data center 62 to use various resources and databases. Further, the system enables clinicians and physicians at remote station 66 to access databases relating to patient data and product information. Additionally, remote clinician or physician station 66 is in data communications with IMDs 10 , 10 ′, 10 ″ and programmer 20 or IMU 20 ′ via link I. Although the primary aspect of the invention relates to accessing patient and/or device related databases, another aspect of the invention provides transfer of device and patient information to the remote database. Specifically, the scheme disclosed in the present invention may enable user/operator to transfer data to remote data center via programmer 20 or IMU 20 ′, allowing each additional patient implanted with a device and subsequent follow-up information to augment the remote database statistical probability data. [0066] As discussed hereinabove, data center 62 is preferably in wireless communications with programmer 20 or IMU 20 ′. The medium of communications between programmer 20 and data center 62 may be selected from one or a combination of several cable and wireless systems discussed hereinabove. Further, programmer 20 is in wireless communications with a number of IMDs, such as shown in FIG. 1. Although three IMDs are shown for illustrative purposes, it should be noted that several IMDs may be implemented and the practice of the present invention does not limit the number of implants per se. [0067] Referring to programmer 20 in more detail, when a physician or an operator needs to interact with programmer 20 , a keyboard coupled to Processor 80 is optionally employed. However the primary communication mode may be through graphics display screen of the well-known “touch sensitive” type controlled by graphics circuit. A user of programmer 20 may interact therewith through the use of a stylus, also coupled to a graphics circuit, which is used to point to various locations on a screen/display to display menu choices for selection by the user or an alphanumeric keyboard for entering text or numbers and other symbols as shown in the above-incorporated '362 patent. Various touch-screen assemblies are known and commercially available. The display and or the keyboard of programmer 20 , preferably include means for entering command signals from the operator to initiate transmissions of downlink telemetry from IMDs and to initiate and control telemetry sessions once a telemetry link with one or more IMDs has been established. The graphics display /screen is also used to display patient related data and menu choices and data entry fields used in entering the data in accordance with the present invention as described below. Graphics display/screen also displays a variety of screens of telemetered out data or real-time data. Programmer 20 is also provided with a strip chart printer or the like coupled to an interface controller module so that a hard copy of a patient's ECG, EGM, marker channel or similar graphics display can be generated. Further, Programmer 20 's history relating to instrumentation and software status may be printed from the printer. Similarly, once an uplink is established between programmer 20 and any one of IMDs 10 , 10 ′ and 10 ″, various patient history data and IMD performance data may be printed out. The IMDs contemplated by the present invention include a cardiac pacemaker, a defibrillator, a pacer-defibrillator, implantable monitor, cardiac assist device, and similar implantable devices for cardiac rhythm and therapy. Further the IMD units contemplated by the present invention include electrical stimulators such as, but not limited to, a drug delivery system, a neural stimulator, a neural implant, a nerve or muscle stimulator or any other implant designed to provide physiologic assistance or clinical therapy. [0068] The communications link/connections such as links A, B, C, D, E, H and I may be one of a variety of links or interfaces, such as a local area network (LAN), an internet connection, a telephone line connection, a satellite connection, a global positioning system (GPS) connection, a cellular connection, a cable connection, a laser wave generator system, any combination thereof, or equivalent data communications links. [0069] As stated hereinabove, the bi-directional wireless communications 136 acts as a direct conduit for information exchange between remote data center 62 and programmer 20 . Further, bi-directional wireless communications 136 provides an indirect link between remote data center and IMDs 10 , 10 ′ and 10 ″ via programmer 20 . In the context of this disclosure the word “data” when used in conjunction with bi-directional wireless communications also refers to sound, video and information transfer between the various centers. [0070] [0070]FIG. 6 shows a flow diagram 200 of a method of practicing the invention described herein. The method is initiated at step 202 whereby programmer 20 at step 204 interrogates the IMD(S) 10 , 10 ′ and 10 ″. The model number and serial number of the IMD is compared to an advisory or recall list at step 206 . If the device being interrogated is not on the list, the flow diagram proceeds, via step 210 , to step 212 . If the IMD is found to be on a list for notification, a report is generated at step 208 . [0071] At step 212 , the uplinked battery status, battery voltage and/or battery impedance is compared to limits for the particular IMD. Measurements may be made by any of several methods, one as described in U.S. Pat. No. 5,137,020 to Wayne, et, al. Other impedance measurement circuits are also known in the art and believed to be suitable for the purposes of the present invention; see, for example, U.S. Pat. No. 4,606,350 to Frost. Both patents are herein incorporated by reference in their entireties. At step 212 , if the battery status is at elective replacement time (e.g., ERT), a report is generated at step 214 . [0072] If the battery status is not yet at, or beyond ERT, at step 212 , a remaining IMD longevity is projected based upon the survivability probability data as provided by the periodically published Medtronic Product Performance Report (a summary report/projection of the implanted database of all implanted devices of similar model and parameter settings is projected in a statistical survival probability model), the stored diagnostic data from the IMD (e.g., average pacing rate, maximum pacing rate achieved, percent pacing, programmable output pulse settings, frequency and lengths of mode switches, etc.), and the present measured battery voltage or impedance. Diagnostic data stored and subsequently retrieved from the IMD may be as substantially described in U.S. Pat. No. 5,330,513 to Nichols, et. al., incorporated herein by reference in its entirety. At step 218 , the measured lead impedance from IMD 10 is compared to limits to verify lead viability, expected longevity, and function per recommendations in the Product Performance Report. As an example, if the lead impedance is less than 250 ohms and/or has changed 30% from the value measured at implant, when measured at step 218 , a recommended course of action and report is generated at step 220 . This action may include prophylactic replacement of the lead, decreased follow-up intervals, or parameter changes to the IMD (e.g., increased pacing amplitude/pulse width, sensitivity threshold adjustments, mode changes, etc.). If the lead impedance measurements are within normal range, a longevity projection is performed at step 222 based upon the actual impedance measurement and historical data from the implanted database of similar model and parameter settings. [0073] The reports and recommendations generated at steps 208 , 214 , and 220 may be displayed on the programmer 20 screen and/or printed for insertion into a hardcopy patient file at step 224 . These recommendations may be provided to the physician at step 224 to maximize longevity, improve patient benefit and/or increase reliability of device function by adjustment of programmable parameter settings or change courses of medical treatment (e.g., initial choice of device, prophylactic replacement, change of follow-up frequency, etc.). [0074] [0074]FIGS. 7 and 8 show an example of the device survival probability percent versus years after implant of various leads 300 and pacemakers 400 , respectively. Plots 302 , 304 , 306 , 308 and 310 are representative obsolete bipolar leads based on lead complications in a chronic lead study. Error bars represent 2 standard errors at the leading 6-month interval. Survival probability refers to the continued proper function of a lead type. For example, at 16 years post implant, lead 310 would have a 93% survival probability (or alternatively, each patient would have a 7% risk of incurring a lead failure and/or complication). [0075] Plots 402 , 404 , 406 , 408 and 410 are representative obsolete dual chamber pacemakers based on returned product analysis. Error bars represent 2 standard errors at the leading 3-month interval. Survival probability refers to the continued proper function of a device type. For example, at 10 years post implant, pacemaker 410 would have a 49% survival probability (or alternatively, each patient would have a 51% risk of incurring a pacemaker normal battery depletion, failure and/or complication). [0076] Accordingly, the present invention provides inter alia, a system of notification of recalls and alerts, recommendations for enhanced device longevity, and recommendations for improved patient benefit and safety for IMDs via programmers or IMUs worldwide. Generally, in the context of the invention, all programmers or IMUs located proximate to IMDs or patients with IMDs and distributed globally are connected to an expert data center to share software upgrades and access archived data. The programmer or IMU function as an interface between the remotely located expert data center and the IMDs. Further, procedural functions such as monitoring the performance of the IMDs, upkeep and maintenance of the IMDs, recommendations for the programming of parameters of IMDs, prophaylactic replacement of IMDs, recommendations on the frequency of follow-up and other actions related to the patient as needed are implemented via reports to the Physician, or healthcare professional via the programmer or the IMU. Further, a physician at a remote station is preferably wirelessly linked to the remote expert data center. This scheme enables the optimization of patient care and IMD function by physicians worldwide while maintaining a high standard of patient care at reduced costs. [0077] Although specific embodiments of the invention have been set forth herein in some detail, it is understood that this has been done for the purposes of illustration only and is not to be taken as a limitation on the scope of the invention as defined in the appended claims. It is to be understood that various alterations, substitutions, and modifications may be made to the embodiment described herein without departing from the spirit and scope of the appended claims.

A method and structure for notifying clinicians with patients with implantable medical devices (IMDs), about recalls and upgrades, therapy improvements, longevity estimates/improvements, and follow-up frequency recommendations is implemented in an interactive preferably wireless communications system involving a preferably web-enabled remote expert station. Either the clinician or the patient may initiate and access the remote expert station. During such communications, the patient's IMDs are evaluated against a first database comprising patient data and a second database comprising statistical, survivability, probability projections. The patient or the clinician may also access a database containing patient-specific information including other device information. If one or more of the patient's IMDs matches with a recalled or an up-gradable unit such message is posted to the clinician and the patient. Remedial action is taken, by replacing the unit, upgrading/reprogramming the unit, adjusting the patient's follow-up timing to thereby ensure effective and safe therapy and clinical care.

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is claims priority to U.S. Provisional Application Ser. No. 60/291,215 of Fei Mao, filed on May 15, 2001 and entitled “Biosensor Membranes Composed of Polyvinylpyridines”, which is incorporated herein in its entirety by this reference. FIELD OF THE INVENTION [0002] This invention generally relates to an analyte-flux-limiting membrane. More particularly, the invention relates to such a membrane composed of polymers containing heterocyclic nitrogens. The membrane is a useful component in biosensors, and more particularly, in biosensors that can be implanted in a living body. BACKGROUND OF THE INVENTION [0003] Enzyme-based biosensors are devices in which an analyte-concentration-dependent biochemical reaction signal is converted into a measurable physical signal, such as an optical or electrical signal. Such biosensors are widely used in the detection of analytes in clinical, environmental, agricultural and biotechnological applications. Analytes that can be measured in clinical assays of fluids of the human body include, for example, glucose, lactate, cholesterol, bilirubin and amino acids. The detection of analytes in biological fluids, such as blood, is important in the diagnosis and the monitoring of many diseases. [0004] Biosensors that detect analytes via electrical signals, such as current (amperometric biosensors) or charge (coulometric biosensors), are of special interest because electron transfer is involved in the biochemical reactions of many important bioanalytes. For example, the reaction of glucose with glucose oxidase involves electron transfer from glucose to the enzyme to produce gluconolactone and reduced enzyme. In an example of an amperometric glucose biosensor, glucose is oxidized by oxygen in the body fluid via a glucose oxidase-catalyzed reaction that generates gluconolactone and hydrogen peroxide, whereupon the hydrogen peroxide is electrooxidized and correlated to the concentration of glucose in the body fluid. (Thomé-Duret, V., et al., Anal. Chem. 68, 3822 (1996); and U.S. Pat. No. 5,882,494 of Van Antwerp.) In another example of an amperometric glucose biosensor, the electrooxidation of glucose to gluconolactone is mediated by a polymeric redox mediator that electrically “wires” the reaction center of the enzyme to an electrode. (Csöregi, E., et al., Anal. Chem. 66, 3131 (1994); Csöregi, E., et al., Anal. Chem. 67, 1240 (1995); Schmidtke, D. W., et al., Anal. Chem. 68, 2845 (1996); Schmidtke, D. W., et al., Anal. Chem. 70, 2149 (1998); and Schmidtke, D. W., et al., Proc. Natl. Acad. Sci. U.S.A. 95, 294 (1998).) [0005] Amperometric biosensors typically employ two or three electrodes, including at least one measuring or working electrode and one reference electrode. In two-electrode systems, the reference electrode also serves as a counter-electrode. In three-electrode systems, the third electrode is a counter-electrode. The measuring or working electrode is composed of a non-corroding carbon or a metal conductor and is connected to the reference electrode via a circuit, such as a potentiostat. [0006] Some biosensors are designed for implantation in a living animal body, such as a mammalian or a human body, merely by way of example. In an implantable amperometric biosensor, the working electrode is typically constructed of a sensing layer, which is in direct contact with the conductive material of the electrode, and a diffusion-limiting membrane layer on top of the sensing layer. The sensing layer typically consists of an enzyme, an enzyme stabilizer such as bovine serum albumin (BSA), and a crosslinker that crosslinks the sensing layer components. Alternatively, the sensing layer consists of an enzyme, a polymeric mediator, and a crosslinker that crosslinks the sensing layer components, as in the above-mentioned “wired-enzyme” biosensor. [0007] In an implantable amperometric glucose sensor, the membrane is often beneficial or necessary for regulating or limiting the flux of glucose to the sensing layer. By way of explanation, in a glucose sensor without a membrane, the flux of glucose to the sensing layer increases linearly with the concentration of glucose. When all of the glucose arriving at the sensing layer is consumed, the measured output signal is linearly proportional to the flux of glucose and thus to the concentration of glucose. However, when the glucose consumption is limited by the kinetics of chemical or electrochemical activities in the sensing layer, the measured output signal is no longer controlled by the flux of glucose and is no longer linearly proportional to the flux or concentration of glucose. In this case, only a fraction of the glucose arriving at the sensing layer is consumed before the sensor becomes saturated, whereupon the measured signal stops increasing, or increases only slightly, with the concentration of glucose. In a glucose sensor equipped with a diffusion-limiting membrane, on the other hand, the membrane reduces the flux of glucose to the sensing layer such that the sensor does not become saturated and can therefor operate effectively within a much wider range of glucose concentration. [0008] More particularly, in these membrane-equipped glucose sensors, the glucose consumption rate is controlled by the diffusion or flux of glucose through the membrane rather than by the kinetics of the sensing layer. The flux of glucose through the membrane is defined by the permeability of the membrane to glucose, which is usually constant, and by the concentration of glucose in the solution or biofluid being monitored. When all of the glucose arriving at the sensing layer is consumed, the flux of glucose through the membrane to the sensing layer varies linearly with the concentration of glucose in the solution, and determines the measured conversion rate or signal output such that it is also linearly proportional to the concentration of glucose concentration in the solution. Although not necessary, a linear relationship between the output signal and the concentration of glucose in the solution is ideal for the calibration of an implantable sensor. [0009] Implantable amperometric glucose sensors based on the electrooxidation of hydrogen peroxide, as described above, require excess oxygen reactant to ensure that the sensor output is only controlled by the concentration of glucose in the body fluid or tissue being monitored. That is, the sensor is designed to be unaffected by the oxygen typically present in body fluid or tissue. In body tissue in which the glucose sensor is typically implanted, the concentration of oxygen can be very low, such as from about 0.02 mM to about 0.2 mM, while the concentration of glucose can be as high as about 30 mM or more. Without a glucose-diffusion-limiting membrane, the sensor would become saturated very quickly at very low glucose concentrations. The sensor thus benefits from having a sufficiently oxygen-permeable membrane that restricts glucose flux to the sensing layer, such that the so-called “oxygen-deficiency problem,” a condition in which there is insufficient oxygen for adequate sensing to take place, is minimized or eliminated. [0010] In implantable amperometric glucose sensors that employ wired-enzyme electrodes, as described above, there is no oxygen-deficiency problem because oxygen is not a necessary reactant. Nonetheless, these sensors require glucose-diffusion-limiting membranes because typically, for glucose sensors that lack such membranes, the current output reaches a maximum level around or below a glucose concentration of 10 mM, which is well below 30 mM, the high end of clinically relevant glucose concentration. [0011] A diffusion-limiting membrane is also of benefit in a biosensor that employs a wired-enzyme electrode, as the membrane significantly reduces chemical and biochemical reactivity in the sensing layer and thus reduces the production of radical species that can damage the enzyme. The diffusion-limiting membrane may also act as a mechanical protector that prevents the sensor components from leaching out of the sensor layer and reduces motion-associated noise. [0012] There have been various attempts to develop a glucose-diffusion-limiting membrane that is mechanically strong, biocompatible, and easily manufactured. For example, a laminated microporous membrane with mechanical holes has been described (U.S. Pat. No. 4,759,828 of Young et al.) and membranes formed from polyurethane are also known (Shaw, G. W., et al., Biosensors and Bioelectronics 6, 401 (1991); Bindra, D. S., et al., Anal. Chem. 63, 1692 (1991); Shichiri, M., et al., Horm. Metab. Res., Suppl. Ser. 20, 17 (1988)). Supposedly, glucose diffuses through the mechanical holes or cracks in these various membranes. Further by way of example, a heterogeneous membrane with discrete hydrophobic and hydrophilic regions (U.S. Pat. No. 4,484,987 of Gough) and homogenous membranes with both hydrophobic and hydrophilic functionalities (U.S. Pat. Nos. 5,284,140 and 5,322,063 of Allen et al.) have been described. However, all of these known membranes are difficult to manufacture and have inadequate physical properties. [0013] An improved membrane formed from a complex mixture of a diisocyanate, a diol, a diamine and a silicone polymer has been described in U.S. Pat. Nos. 5,777,060 (Van Antwerp), 5,786,439 (Van Antwerp et al.) and 5,882,494 (Van Antwerp). As described therein, the membrane material is simultaneously polymerized and crosslinked in a flask; the resulting polymeric material is dissolved in a strong organic solvent, such as tetrahydroforan (THF); and the resulting solution is applied onto the sensing layer to form the membrane. Unfortunately, a very strong organic solvent, such as THF, can denature the enzyme in the sensing layer and also dissolve conductive ink materials as well as any plastic materials that may be part of the sensor. Further, since the polymerization and crosslinking reactions are completed in the reaction flask, no further bond-making reactions occur when the solution is applied to the sensing layer to form the membrane. As a result, the adhesion between the membrane layer and sensing layer may not be adequate. [0014] In the published Patent Cooperation Treaty (PCT) Application bearing International Publication No. WO 01/57241 A2, Kelly and Schiffer describe a method for making a glucose-diffusion-limiting membrane by photolytically polymerizing small hydrophilic monomers. The sensitivities of the glucose sensors employing such membranes are widely scattered, however, indicating a lack of control in the membrane-making process. Further, as the polymerization involves very small molecules, it is quite possible that small, soluble molecules remain after polymerization, which may leach out of the sensor. Thus, glucose sensors employing such glucose-diffusion-limiting membranes may not be suitable for implantation in a living body. SUMMARY OF THE INVENTION [0015] The present invention is directed to membranes composed of crosslinked polymers containing heterocyclic nitrogen groups, particularly polymers of polyvinylpyridine and polyvinylimidazole, and to electrochemical sensors equipped with such membranes. The membranes are useful in limiting the flux of an analyte to a working electrode in an electrochemical sensor so that the sensor is linearly responsive over a large range of analyte concentrations and is easily calibrated. Electrochemical sensors equipped with membranes of the present invention demonstrate considerable sensitivity and stability, and a large signal-to-noise ratio, in a variety of conditions. [0016] According to one aspect of the invention, the membrane is formed by crosslinking in situ a polymer, modified with a zwitterionic moiety, a non-pyridine copolymer component, and optionally another moiety that is either hydrophilic or hydrophobic, and/or has other desirable properties, in an alcohol-buffer solution. The modified polymer is made from a precursor polymer containing heterocyclic nitrogen groups. Preferably, the precursor polymer is polyvinylpyridine or polyvinylimidazole. When used in an electrochemical sensor, the membrane limits the flux of an analyte reaching a sensing layer of the sensor, such as an enzyme-containing sensing layer of a “wired enzyme” electrode, and further protects the sensing layer. These qualities of the membrane significantly extend the linear detection range and the stability of the sensor. [0017] In the membrane formation process, the non-pyridine copolymer component generally enhances the solubility of the polymer and may provide further desirable physical or chemical properties to the polymer or the resulting membrane. Optionally, hydrophilic or hydrophobic modifiers may be used to “fine-tune” the permeability of the resulting membrane to an analyte of interest. Optional hydrophilic modifiers, such as poly(ethylene glycol), hydroxyl or polyhydroxyl modifiers, may be used to enhance the biocompatibility of the polymer or the resulting membrane. In the formation of a membrane of the present invention, the zwitterionic moiety of the polymer is believed to provide an additional layer of crosslinking, via intermolecular electrostatic bonds, beyond the basic crosslinking generally attributed to covalent bonds, and is thus believed to strengthen the membrane. [0018] Another aspect of the invention concerns the preparation of a substantially homogeneous, analyte-diffusion-limiting membrane that may be used in a biosensor, such as an implantable amperometric biosensor. The membrane is formed in situ by applying an alcohol-buffer solution of a crosslinker and a modified polymer over an enzyme-containing sensing layer and allowing the solution to cure for one to two days. The crosslinker-polymer solution may be applied to the sensing layer by placing a droplet or droplets of the solution on the sensor, by dipping the sensor into the solution, or the like. Generally, the thickness of the membrane is controlled by the concentration of the solution, by the number of droplets of the solution applied, by the number of times the sensor is dipped in the solution, or by any combination of the these factors. Amperometric glucose sensors equipped with diffusion-limiting membranes of the present invention demonstrate excellent stability and fast and linear responsivity to glucose concentration over a large glucose concentration range. BRIEF DESCRIPTION OF THE DRAWINGS [0019] FIG. 1 is an illustration of a typical structure of a section of an analyte-diffusion-limiting membrane, according to the present invention. [0020] FIG. 2A is a schematic, side-view illustration of a portion of a two-electrode glucose sensor having a working electrode, a combined counter/reference electrode, and a dip-coated membrane that encapsulates both electrodes, according to the present invention. FIGS. 2B and 2C are schematic top- and bottom-view illustrations, respectively, of the portion of the glucose sensor of FIG. 2A . Herein, FIGS. 2A , 2 B and 2 C may be collectively referred to as FIG. 2 . [0021] FIG. 3 is a graph of current versus glucose concentration for sensors having glucose-diffusion-limiting membranes, according to the present invention, and for sensors lacking such membranes, based on average values. [0022] FIG. 4 is a graph of current output versus time at fixed glucose concentration for a sensor having a glucose-diffusion-limiting membrane, according to the present invention, and for a sensor lacking such a membrane. [0023] FIG. 5 is a graph of current output versus time at different levels of glucose concentration for sensors having glucose-diffusion-limiting membranes, according to the present invention, based on average values. [0024] FIG. 6 is a graph of current output versus time at different levels of glucose concentration, with and without stirring, for a sensor having a glucose-diffusion-limiting membrane, according to the present invention, and for a sensor lacking such a membrane. [0025] FIG. 7A is a graph of current output versus glucose concentration for four separately prepared batches of sensors having glucose-diffusion-limiting membranes, according to the present invention, based on average values. FIGS. 7B-7E are graphs of current output versus glucose concentration for individual sensors in each of the four above-referenced batches of sensors having glucose-diffusion-limiting membranes, respectively, according to the present invention. Herein, FIGS. 7A , 7 B, 7 C, 7 D and 7 E may be collectively referred to as FIG. 7 . DESCRIPTION OF THE INVENTION [0026] When used herein, the terms in quotation marks are defined as set forth below. [0027] The term “alkyl” includes linear or branched, saturated aliphatic hydrocarbons. Examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl and the like. Unless otherwise noted, the term “alkyl” includes both alkyl and cycloalkyl groups. [0028] The term “alkoxy” describes an alkyl group joined to the remainder of the structure by an oxygen atom. Examples of alkoxy groups include methoxy, ethoxy, n-propoxy, isopropoxy, butoxy, tert-butoxy, and the like. In addition, unless otherwise noted, the term ‘alkoxy’ includes both alkoxy and cycloalkoxy groups. The term “alkenyl” describes an unsaturated, linear or branched aliphatic hydrocarbon having at least one carbon-carbon double bond. Examples of alkenyl groups include ethenyl, 1-propenyl, 2-propenyl, 1-butenyl, 2-methyl-1-propenyl, and the like. [0029] A “reactive group” is a functional group of a molecule that is capable of reacting with another compound to couple at least a portion of that other compound to the molecule. Reactive groups include carboxy, activated ester, sulfonyl halide, sulfonate ester, isocyanate, isothiocyanate, epoxide, aziridine, halide, aldehyde, ketone, amine, acrylamide, thiol, acyl azide, acyl halide, hydrazine, hydroxylamine, alkyl halide, imidazole, pyridine, phenol, alkyl sulfonate, halotriazine, imido ester, maleimide, hydrazide, hydroxy, and photo-reactive azido aryl groups. Activated esters, as understood in the art, generally include esters of succinimidyl, benzotriazolyl, or aryl substituted by electron-withdrawing groups such as sulfo, nitro, cyano, or halo groups; or carboxylic acids activated by carbodiimides. [0030] A “substituted” functional group (e.g., substituted alkyl, alkenyl, or alkoxy group) includes at least one substituent selected from the following: halogen, alkoxy, mercapto, aryl, alkoxycarbonyl, alkylaminocarbonyl, dialkylaminocarbonyl, —OH, —NH2, alkylamino, dialkylamino, trialkylammonium, alkanoylamino, arylcarboxamido, hydrazino, alkylthio, alkenyl, and reactive groups. [0031] A “crosslinker” is a molecule that contains at least two reactive groups capable of linking at least two molecules together, or linking at least two portions of the same molecule together. Linking of at least two molecules is called intermolecular crosslinking, while linking of at least two portions of the same molecule is called intramolecular crosslinking. A crosslinker having more than two reactive groups may be capable of both intermolecular and intramolecular crosslinkings at the same time. [0032] The term “precursor polymer” refers to the starting polymer before the various modifier groups are attached to form a modified polymer. [0033] The term “heterocyclic nitrogen group” refers to a cyclic structure containing a sp 2 hybridized nitrogen in a ring of the structure. [0034] The term “polyvinylpyridine” refers to poly(4-vinylpyridine), poly(3-vinylpyridine), or poly(2-vinylpyridine), as well as any copolymer of vinylpyridine and a second or a third copolymer component. [0035] The term “polyvinylimidazole” refers to poly(1-vinylimidazole), poly(2-vinylimidazole), or poly(4-vinylimidazole). [0036] A “membrane solution” is a solution that contains all necessary components for crosslinking and forming the membrane, including a modified polymer containing heterocyclic nitrogen groups, a crosslinker and a buffer or an alcohol-buffer mixed solvent. [0037] A “biological fluid” or “biofluid” is any body fluid or body fluid derivative in which the analyte can be measured, for example, blood, interstitial fluid, plasma, dermal fluid, sweat, and tears. [0038] An “electrochemical sensor” is a device configured to detect the presence of or measure the concentration or amount of an analyte in a sample via electrochemical oxidation or reduction reactions. Typically, these reactions can be transduced to an electrical signal that can be correlated to an amount or concentration of analyte. [0039] A “redox mediator” is an electron-transfer agent for carrying electrons between an analyte, an analyte-reduced or analyte-oxidized enzyme, and an electrode, either directly, or via one or more additional electron-transfer agents. A redox mediator that includes a polymeric backbone may also be referred to as a “redox polymer”. [0040] The term “reference electrode” includes both a) reference electrodes and b) reference electrodes that also function as counter electrodes (i.e., counter/reference electrodes), unless otherwise indicated. [0041] The term “counter electrode” includes both a) counter electrodes and b) counter electrodes that also function as reference electrodes (i.e., counter/reference electrodes), unless otherwise indicated. [0042] In general, membrane of the present invention is formed by crosslinking a modified polymer containing heterocyclic nitrogen groups in an alcohol-buffer mixed solvent and allowing the membrane solution to cure over time. The polymer comprises poly(heterocyclic nitrogen-containing constituent) as a portion of its backbone and additional elements, including a zwitterionic moiety, a hydrophobic moiety, and optionally, a biocompatible moiety. The resulting membrane is capable of limiting the flux of an analyte from one space, such as a space associated with a biofluid, to another space, such as space associated with an enzyme-containing sensing layer. An amperometric glucose sensor constructed of a wired-enzyme sensing layer and a glucose-diffusion-limiting layer of the present invention is very stable and has a large linear detection range. Heterocyclic-Nitrogen Containing Polymers [0043] The polymer of the present invention has the following general formula, Formula 1a: [0000] [0000] wherein the horizontal line represents a polymer backbone; A is an alkyl group substituted with a water soluble group, preferably a negatively charged group, such as sulfonate, phosphate, or carboxylate, and more preferably, a strong acid group such as sulfonate, so that the quaternized heterocyclic nitrogen to which it is attached is zwitterionic; D is a copolymer component of the polymer, as further described below; each of n, l, and p is independently an average number of an associated polymer unit or polymer units shown in the closest parentheses to the left; and q is a number of a polymer unit or polymer units shown in the brackets. [0044] The heterocyclic nitrogen groups of Formula 1a include, but are not limited to, pyridine, imidazole, oxazole, thiazole, pyrazole, or any derivative thereof. Preferably, the heterocyclic nitrogen groups are independently vinylpyridine, such as 2-, 3-, or 4-vinylpyridine, or vinylimidazole, such as 1-, 2-, or 4-vinylimidazole. More preferably, the heterocyclic nitrogen groups are independently 4-vinylpyridine, such that the more preferable polymer is a derivative of poly(4-vinylpyridine). An example of such a poly(4-vinylpyridine) of the present invention has the following general formula, Formula 1b: [0000] [0000] wherein A, D, n, l, p and q are as described above in relation to Formula 1a. [0045] While the polymer of the present invention has the general Formula 1a or Formula 1b above, it should be noted that when A is a strong acid, such as a stronger acid than carboxylic acid, the D component is optional, such that p may equal zero. Such a polymer of the present invention has the following general formula, Formula 1c: [0000] [0000] wherein A is a strong acid and the heterocyclic nitrogen groups, n, l and q are all as described above. Sulfonate and fluorinated carboxylic acid are examples of suitably strong acids. It is believed that when A is a sufficiently strong acid, the heterocyclic nitrogen to which it is attached becomes zwitterionic and thus capable of forming intermolecular electrostatic bonds with the crosslinker during membrane formation. It is believed that these intermolecular electrostatic bonds provide another level of crosslinking, beyond the covalent bonds typical of crosslinking, and thus make the resulting membrane stronger. As a result, when A is a suitably strong acid, the D component, which is often a strengthening component such as styrene, may be omitted from the polymers of Formulas 1a and 1b above. When A is a weaker acid, such that the heterocyclic nitrogen is not zwitterionic or capable of forming intermolecular electrostatic bonds, the polymer of the present invention does include D, as shown in Formulas 1a and 1b above. [0046] Examples of A include, but are not limited to, sulfopropyl, sulfobutyl, carboxypropyl, and carboxypentyl. In one embodiment of the invention, group A has the formula -L-G, where L is a C2-C12 linear or branched alkyl linker optionally and independently substituted with an aryl, alkoxy, alkenyl, alkynyl, —F, —Cl, —OH, aldehyde, ketone, ester, or amide group, and G is a negatively charged carboxy or sulfonate group. The alkyl portion of the substituents of L have 1-6 carbons and are preferably an aryl, —OH or amide group. [0047] A can be attached to the heterocyclic nitrogen group via quaternization with an alkylating agent that contains a suitable linker L and a negatively charged group G, or a precursor group that can be converted to a negatively charged group G at a later stage. Examples of suitable alkylating agents include, but are not limited to, 2-bromoethanesulfonate, propanesultone, butanesultone, bromoacetic acid, 4-bromobutyric acid and 6-bromohexanoic acid. Examples of alkylating agents containing a precursor group include, but are not limited to, ethyl bromoacetate and methyl 6-bromohexanoate. The ethyl and methyl ester groups of these precursors can be readily converted to a negatively charged carboxy group by standard hydrolysis. [0048] Alternatively, A can be attached to the heterocyclic nitrogen group by quaternizing the nitrogen with an alkylating agent that contains an additional reactive group, and subsequently coupling, via standard methods, this additional reactive group to another molecule that contains a negatively charged group G and a reactive group. Typically, one of the reactive groups is an electrophile and the other reactive group is a nucleophile. Selected examples of reactive groups and the linkages formed from their interactions are shown in Table 1. [0000] TABLE 1 Examples of Reactive Groups and Resulting Linkages First Reactive Group Second Reactive Group Resulting Linkage Activated ester* Amine Amide Acrylamide Thiol Thioether Acyl azide Amine Amide Acyl halide Amine Amide Carboxylic acid Amine Amide Aldehyde or ketone Hydrazine Hydrazone Aldehyde or ketone Hydroxyamine Oxime Alkyl halide Amine Alkylamine Alkyl halide Carboxylic acid Ester Alkyl halide Imidazole Imidazolium Alkyl halide Pyridine Pyridinium Alkyl halide Alcohol/phenol Ether Alkyl halide Thiol Thioether Alkyl sulfonate Thiol Thioether Alkyl sulfonate Pyridine Pyridinium Alkyl sulfonate Imidazole Imidazolium Alkyl sulfonate Alcohol/phenol Ether Anhydride Alcohol/phenol Ester Anhydride Amine Amide Aziridine Thiol Thioether Aziridine Amine Alkylamine Aziridine Pyridine Pyridinium Epoxide Thiol Thioether Epoxide Amine Alkylamine Epoxide Pyridine Pyridinium Halotriazine Amine Aminotriazine Halotriazine Alcohol Triazinyl ether Imido ester Amine Amidine Isocyanate Amine Urea Isocyanate Alcohol Urethane Isothiocyanate Amine Thiourea Maleimide Thiol Thioether Sulfonyl halide Amine Sulfonamide *Activated esters, as understood in the art, generally include esters of succinimidyl, benzotriazolyl, or aryl substituted by electron-withdrawing groups such as sulfo, nitro, cyano, or halo; or carboxylic acids activated by carbodiimides. By way of example, A may be attached to the heterocyclic nitrogen groups of the polymer by quaternizing the heterocyclic nitrogens with 6-bromohexanoic acid and subsequently coupling the carboxy group to the amine group of 3-amino-1-propanesulfonic acid in the presence of a carbodiimide coupling agent. [0049] D is a component of a poly(heterocyclic nitrogen-co-D) polymer of Formula 1a or 1b. Examples of D include, but are not limited to, phenylalkyl, alkoxystyrene, hydroxyalkyl, alkoxyalkyl, alkoxycarbonylalkyl, and a molecule containing a poly(ethylene glycol) or polyhydroxyl group. Some poly(heterocyclic nitrogen-co-D) polymers suitable as starting materials for the present invention are commercially available. For example, poly(2-vinylpyridine-co-styrene), poly(4-vinylpyridine-co-styrene) and poly(4-vinylpyridine-co-butyl methacrylate) are available from Aldrich Chemical Company, Inc. Other poly(heterocyclic nitrogen-co-D) polymers can be readily synthesized by anyone skilled in the art of polymer chemistry using well-known methods. Preferably, D is a styrene or a C1-C18 alkyl methacrylate component of a polyvinylpyridine-poly-D, such as (4-vinylpyrine-co-styrene) or poly(4-vinylpyridine-co-butyl methacrylate), more preferably, the former. D may contribute to various desirable properties of the membrane including, but not limited to, hydrophobicity, hydrophilicity, solubility, biocompatibility, elasticity and strength. D may be selected to optimize or “fine-tune” a membrane made from the polymer in terms of its permeability to an analyte and its non-permeability to an undesirable, interfering component, for example. [0050] The letters n, l, and p designate, respectively, an average number of each copolymer component in each polymer unit. The letter q is one for a block copolymer or a number greater than one for a copolymer with a number of repeating polymer units. By way of example, the q value for a polymer of the present invention may be ≧about 950, where n, l and p are 1, 8 and 1, respectively. The letter q is thus related to the overall molecular weight of the polymer. Preferably, the average molecular weight of the polymer is above about 50,000, more preferably above about 200,000, most preferably above about 1,000,000. [0051] The polymer of the present invention may comprise a further, optional copolymer, as shown in the following general formula, Formula 2a: [0000] [0000] wherein the polymer backbone, A, D, n, 1, p and q are as described above in relation to Formulas 1a-1c; m is an average number of an associated polymer unit or polymer units shown in the closest parentheses to the left; and B is a modifier. When the heterocyclic nitrogen groups are 4-substituted pyridine, as is preferred, the polymer of the present invention is derivative of poly(4-vinylpyridine) and has the general formula, Formula 2b, set forth below. [0000] [0052] Further, when A is a suitably strong acid, as described above, the D copolymer is optional, in which case the polymer of the present invention has the general formula, Formula 2c: [0000] [0053] In any of Formulas 2a-2c, B is a modifier group that may add any desired chemical, physical or biological properties to the membrane. Such desired properties include analyte selectivity, hydrophobicity, hydrophilicity, elasticity, and biocompatibility. Examples of modifiers include the following: negatively charged molecules that may minimize entrance of negatively charged, interfering chemicals into the membrane; hydrophobic hydrocarbon molecules that may increase adhesion between the membrane and sensor substrate material; hydrophilic hydroxyl or polyhydroxy molecules that may help hydrate and add biocompatibility to the membrane; silicon polymers that may add elasticity and other properties to the membrane; and poly(ethylene glycol) constituents that are known to increase biocompatibility of biomaterials (Bergstrom, K., et al., J. Biomed. Mat. Res. 26, 779 (1992)). Further examples of B include, but are not limited to, a metal chelator, such as a calcium chelator, and other biocompatible materials. A poly(ethylene glycol) suitable for biocompatibility modification of the membrane generally has a molecular weight of from about 100 to about 20,000, preferably, from about 500 to about 10,000, and more preferably, from about 1,000 to about 8,000. [0054] The modifier B can be attached to the heterocyclic nitrogens of the polymer directly or indirectly. In direct attachment, the heterocyclic nitrogen groups may be reacted with a modifier containing an alkylating group. Suitable alkylating groups include, but are not limited to, alkyl halide, epoxide, aziridine, and sulfonate esters. In indirect attachment, the heterocyclic nitrogens of the polymer may be quaternized with an alkylating agent having an additional reactive group, and then attached to a molecule having a desired property and a suitable reactive group. [0055] As described above, the B-containing copolymer is optional in the membrane of the present invention, such that when m of Formula 2a-2c is zero, the membrane has the general formula of Formula 1a-1c, respectively. The relative amounts of the four copolymer components, the heterocyclic nitrogen group containing A, the optional heterocyclic nitrogen group containing B, the heterocyclic nitrogen group, and D, may be expressed as percentages, as follows: [n/(n+m+l+p)]×100%, [m/(n+m+l+p)]×100%, [l/(n+m+l+p)]×100%, and [p/(n+m+l+p)]×100%, respectively. Suitable percentages are 1-25%, 0-15% (when the B-containing heterocyclic nitrogen group is optional) or 1-15%, 20-90%, and 0-50% (when D is optional) or 1-50%, respectively, and preferable percentages are 5-20%, 0-10% (when the B-containing heterocyclic nitrogen group is optional) or 1-10%, 60-90%, and 5-20%, respectively. [0056] Specific examples of suitable polymers have the general formulas, Formulas 3-6, shown below. [0000] EXAMPLES OF SYNTHESES OF POLYVINYLPYRIDINE POLYMERS [0057] Examples showing the syntheses of various polyvinylpyridine polymers according to the present invention are provided below. Numerical figures provided are approximate. Example 1 Synthesis of a Polymer of Formula 3 [0058] By way of illustration, an example of the synthesis of a polymer of Formula 3 above, is now provided. A solution of poly(4-vinylpyridine-co-styrene) (10% styrene content) (20 g, Aldrich) in 100 mL of dimethyl formamide (DMF) at 90° C. was stirred and 6-bromohexanoic acid (3.7 g) in 15-20 mL of DMF was added. The resulting solution was stirred at 90° C. for 24 hours and then poured into 1.5 L of ether, whereupon the solvent was decanted. The remaining, gummy solid was dissolved in MeOH (150-200 mL) and suction-filtered through a medium-pore, fritted funnel to remove any undissolved solid. The filtrate was added slowly to rapidly stirred ether (1.5 L) in a beaker. The resulting precipitate was collected by suction filtration and dried at 50° C. under high vacuum for 2 days. The polymer had the following parameters: [n/(n+l+p)]×100%≈10%; [l/(n+l+p)]×100%≈80%; and [p/(n+l+p)]×100%≈110%. Example 2 Synthesis of a Polymer of Formula 5 [0059] By way of illustration, an example of the synthesis of a polymer of Formula 5 above, is now provided. A solution of poly(4-vinylpyridine-co-styrene) (10% styrene) (20 g, Aldrich) in 100 mL of anhydrous DMF at 90° C. was stirred, methanesulfonic acid (˜80 mg) was added, and then 2 g of methoxy-PEG-epoxide (molecular weight 5,000) (Shearwater Polymers, Inc.) in 15-20 mL of anhydrous DMF was added. The solution was stirred at 90° C. for 24 hours and 1,3-Propane sultone (2.32 g) in 10 mL of anhydrous DMF was added. The resulting solution was continuously stirred at 90° for 24 hours, and then cooled to room temperature and poured into 800 mL of ether. The solvent was decanted and the remaining precipitate was dissolved in hot MeOH (˜200 mL), suction-filtered, precipitated again from 1 L of ether, and then dried at 50° C. under high vacuum for 48 hours. The resulting polymer has the following parameters: [n/(n+m+l+p)]×100%≈10%; [m/(n+m+l+p)]×100%≈10%; [l/(n+m+l+p)]×100%≈70%; and [p/(n+m+l+p)]×100%≈10%. Example 3 Synthesis of a Polymer Having a Polyhydroxy Modifier B [0060] By way of illustration, an example of the synthesis of a polymer having a polyhydroxy modifier B, as schematically illustrated below, is now provided. Various polyhydroxy compounds are known for having biocompatibility properties. (U.S. Pat. No. 6,011,077.) The synthesis below illustrates how a modifier group having a desired property may be attached to the polymer backbone via a linker. [0000] [0000] 1,3-propane sultone (0.58 g, 4.8 mmoles) and 6-bromohexanoic acid (1.85 g, 9.5 mmoles) are added to a solution of poly(4-vinylpyridine-co-styrene) (˜10% styrene) (10 g) dissolved in 60 mL of anhydrous DMF. The resulting solution is stirred at 90° C. for 24 hours and then cooled to room temperature. O—(N-succinimidyl)-N,N,N′,N′-tetramethyl-uronium tetrafluoroborate (TSTU) (2.86 g, 9.5 mmoles) and N,N-diisopropylethylamine (1.65 mL, 9.5 mmoles) are then added in succession to the solution. After the solution is stirred for 5 hours, N-methyl-D-glucamine (2.4 g, 12.4 mmoles) is added and the resulting solution is stirred at room temperature for 24 hours. The solution is poured into 500 ml of ether and the precipitate is collected by suction filtration. The collected precipitate is then dissolved in MeOH/H 2 O and the resulting solution is subjected to ultra membrane filtration using the same MeOH/H 2 O solvent to remove small molecules. The dialyzed solution is evaporated to dryness to give a polymer with the following parameters: [n/(n+m+l+p)]×100%≈10%; [m/(n+m+l+p)]×100%≈10%; [l/(n+m+l+p)]×100%≈70%; and [p/(n+m+l+p)]×100%≈10%. Crosslinkers [0061] Crosslinkers of the present invention are molecules having at least two reactive groups, such as bi-, tri-, or tetra-functional groups, capable of reacting with the heterocyclic nitrogen groups, pyridine groups, or other reactive groups contained on A, B or D of the polymer. Preferably, the reactive groups of the crosslinkers are slow-reacting alkylating groups that can quaternize the heterocyclic nitrogen groups, such as pyridine groups, of the polymer. Suitable alkylating groups include, but are not limited to, derivatives of poly(ethylene glycol) or polypropylene glycol), epoxide (glycidyl group), aziridine, alkyl halide, and sulfonate esters. Alkylating groups of the crosslinkers are preferably glycidyl groups. Preferably, glycidyl crosslinkers have a molecular weight of from about 200 to about 2,000 and are water soluble or soluble in a water-miscible solvent, such as an alcohol. Examples of suitable crosslinkers include, but are not limited to, poly(ethylene glycol) diglycidyl ether with a molecular weight of about 200 to about 600, and N,N-diglycidyl-4-glycidyloxyaniline. [0062] It is desirable to have a slow crosslinking reaction during the dispensing of membrane solution so that the membrane coating solution has a reasonable pot-life for large-scale manufacture. A fast crosslinking reaction results in a coating solution of rapidly changing viscosity, which renders coating difficult. Ideally, the crosslinking reaction is slow during the dispensing of the membrane solution, and accelerated during the curing of the membrane at ambient temperature, or at an elevated temperature where possible. Membrane Formation and Sensor Fabrication [0063] An example of a process for producing a membrane of the present invention is now described. In this example, the polymer of the present invention and a suitable crosslinker are dissolved in a buffer-containing solvent, typically a buffer-alcohol mixed solvent, to produce a membrane solution. Preferably, the buffer has a pH of about 7.5 to about 9.5 and the alcohol is ethanol. More preferably, the buffer is a 10 mM (2-(4-(2-hydroxyethyl)-1-piperazine)ethanesulfonate) (HEPES) buffer (pH 8) and the ethanol to buffer volume ratio is from about 95 to 5 to about 0 to 100. A minimum amount of buffer is necessary for the crosslinking chemistry, especially if an epoxide or aziridine crosslinker is used. The amount of solvent needed to dissolve the polymer and the crosslinker may vary depending on the nature of the polymer and the crosslinker. For example, a higher percentage of alcohol may be required to dissolve a relatively hydrophobic polymer and/or crosslinker. [0064] The ratio of polymer to cross-linker is important to the nature of the final membrane. By way of example, if an inadequate amount of crosslinker or an extremely large excess of crosslinker is used, crosslinking is insufficient and the membrane is weak. Further, if a more than adequate amount of crosslinker is used, the membrane is overly crosslinked such that membrane is too brittle and/or impedes analyte diffusion. Thus, there is an optimal ratio of a given polymer to a given crosslinker that should be used to prepare a desirable or useful membrane. By way of example, the optimal polymer to crosslinker ratio by weight is typically from about 4:1 to about 32:1 for a polymer of any of Formulas 3-6 above and a poly(ethylene glycol) diglycidyl ether crosslinker, having a molecular weight of about 200 to about 400. Most preferably, this range is from about 8:1 to about 16:1. Further by way of example, the optimal polymer to crosslinker ratio by weight is typically about 16:1 for a polymer of Formula 4 above, wherein [n/(n+l+p)]×100%≈10%, [l/(n+l+p)]×100%≈80%, and [p/(n+l+p)]×100%≈10%, or for a polymer of Formula 5 above, wherein [n/(n+m+l+p)]×100%≈10%, [m/(n+m+l+p)]×100%≈10%, [l/(n+m+l+p)]×100%≈70%, [p/(n+m+l+p)]×100%≈10%, and r≈110, and a poly(ethylene glycol) diglycidyl ether crosslinker having a molecular weight of about 200. [0065] The membrane solution can be coated over a variety of biosensors that may benefit from having a membrane disposed over the enzyme-containing sensing layer. Examples of such biosensors include, but are not limited to, glucose sensors and lactate sensors. (See U.S. Pat. No. 6,134,461 to Heller et al., which is incorporated herein in its entirety by this reference.) The coating process may comprise any commonly used technique, such as spin-coating, dip-coating, or dispensing droplets of the membrane solution over the sensing layers, and the like, followed by curing under ambient conditions typically for 1 to 2 days. The particular details of the coating process (such as dip duration, dip frequency, number of dips, or the like) may vary depending on the nature (i.e., viscosity, concentration, composition, or the like) of the polymer, the crosslinker, the membrane solution, the solvent, and the buffer, for example. Conventional equipment may be used for the coating process, such as a DSG D1L-160 dip-coating or casting system of NIMA Technology in the United Kingdom. Example of Sensor Fabrication [0066] Sensor fabrication typically consists of depositing an enzyme-containing sensing layer over a working electrode and casting the diffusion-limiting membrane layer over the sensing layer, and optionally, but preferably, also over the counter and reference electrodes. The procedure below concerns the fabrication of a two-electrode sensor, such as that depicted in FIGS. 2A-2C . Sensors having other configurations such as a three-electrode design can be prepared using similar methods. [0067] A particular example of sensor fabrication, wherein the numerical figures are approximate, is now provided. A sensing layer solution was prepared from a 7.5 mM HEPES solution (0.5 μL, pH 8), containing 1.7 μg of the polymeric osmium mediator compound L, as disclosed in Published Patent Cooperation Treaty (PCT) Application, International Publication No. WO 01/36660 A2, which is incorporated herein in its entirety by this reference; 2.1 μg of glucose oxidase (Toyobo); and 1.3 μg of poly(ethylene glycol) diglycidyl ether (molecular weight 400). Compound L is shown below. [0000] [0000] The sensing layer solution was deposited over carbon-ink working electrodes and cured at room temperature for two days to produce a number of sensors. A membrane solution was prepared by mixing 4 volumes of a polymer of Formula 4 above, dissolved at 64 mg/mL in 80% EtOH/20% HEPES buffer (10 mM, pH 8), and one volume of poly(ethylene glycol) diglycidyl ether (molecular weight 200), dissolved at 4 mg/mL in 80% EtOH/20% HEPES buffer (10 mM, pH 8). The above-described sensors were dipped three times into the membrane solution, at about 5 seconds per dipping, with about a 10-minute time interval between consecutive dippings. The sensors were then cured at room temperature and normal humidity for 24 hours. [0068] An approximate chemical structure of a section of a typical membrane prepared according to the present invention is shown in FIG. 1 . Such a membrane may be employed in a variety of sensors, such as the two- or three-electrode sensors described previously herein. By way of example, the membrane may be used in a two-electrode amperometric glucose sensor, as shown in FIG. 2A-2C (collectively FIG. 2 ) and described below. [0069] The amperometric glucose sensor 10 of FIG. 2 comprises a substrate 12 disposed between a working electrode 14 that is typically carbon-based, and a Ag/AgCl counter/reference electrode 16 . A sensor or sensing layer 18 is disposed on the working electrode. A membrane or membrane layer 20 encapsulates the entire glucose sensor 10 , including the Ag/AgCl counter/reference electrode. [0070] The sensing layer 18 of the glucose sensor 10 consists of crosslinked glucose oxidase and a low potential polymeric osmium complex mediator, as disclosed in the above-mentioned Published PCT Application, International Publication No. WO 01/36660 A2. The enzyme- and mediator-containing formulation that can be used in the sensing layer, and methods for applying them to an electrode system, are known in the art, for example, from U.S. Pat. No. 6,134,461. According to the present invention, the membrane overcoat was formed by thrice dipping the sensor into a membrane solution comprising 4 mg/mL poly(ethylene glycol) diglycidyl ether (molecular weight of about 200) and 64 mg/mL of a polymer of Formula 4 above, wherein [n/(n+l+p)]×100%≈10%; [l/(n+l+p)]×100%≈80%; and [p/(n+l+p)]×100%≈10%, and curing the thrice-dipped sensor at ambient temperature and normal humidity for at least 24 hours, such as for about 1 to 2 days. The q value for such a membrane overcoat may be ≧about 950, where n, l and p are 1, 8 and 1, respectively. Membrane Surface Modification [0071] Polymers of the present invention have a large number of heterocyclic nitrogen groups, such as pyridine groups, only a few percent of which are used in crosslinking during membrane formation. The membrane thus has an excess of these groups present both within the membrane matrix and on the membrane surface. Optionally, the membrane can be further modified by placing another layer of material over the heterocyclic-nitrogen-group-rich or pyridine-rich membrane surface. For example, the membrane surface may be modified by adding a layer of poly(ethylene glycol) for enhanced biocompatibility. In general, modification may consist of coating the membrane surface with a modifying solution, such as a solution comprising desired molecules having an alkylating reactive group, and then washing the coating solution with a suitable solvent to remove excess molecules. This modification should result in a monolayer of desired molecules. [0072] The membrane 20 of the glucose sensor 10 shown in FIG. 2 may be modified in the manner described above. Experimental Examples [0073] Examples of experiments that demonstrate the properties and/or the efficacy of sensors having diffusion-limiting membranes according to the present invention are provided below. Numerical figures provided are approximate. Calibration Experiment [0074] In a first example, a calibration experiment was conducted in which fifteen sensors lacking membranes were tested simultaneously (Set 1), and separately, eight sensors having diffusion-limiting membranes according to the present invention were tested simultaneously (Set 2), all at 37° C. In Set 2, the membranes were prepared from polymers of Formula 4 above and poly(ethylene glycol) diglycidyl ether (PEGDGE) crosslinkers, having a molecular weight of about 200. In the calibration experiment for each of Set 1 and Set 2, the sensors were placed in a PBS-buffered solution (pH 7) and the output current of each of the sensors was measured as the glucose concentration was increased. The measured output currents (μA for Set 1; nA for Set 2) were then averaged for each of Set 1 and Set 2 and plotted against glucose concentration (mM), as shown in the calibration graph of FIG. 3 . [0075] As shown, the calibration curve for the Set 1 sensors lacking membranes is approximately linear over a very small range of glucose concentrations, from zero to about 3 mM, or 5 mM at most. This result indicates that the membrane-free sensors are insufficiently sensitive to glucose concentration change at elevated glucose concentrations such as 10 mM, which is well below the high end of clinically relevant glucose concentration at about 30 mM. By contrast, the calibration curve for the Set 2 sensors having diffusion-limiting membranes according to the present invention is substantially linear over a relatively large range of glucose concentrations, for example, from zero to about 30 mM, as demonstrated by the best-fit line (y=1.2502x+1.1951; R 2 ˜0.997) also shown in FIG. 3 . This result demonstrates the considerable sensitivity of the membrane-equipped membranes to glucose concentration, at low, medium, and high glucose concentrations, and of particular relevance, at the high end of clinically relevant glucose concentration at about 30 mM. Stability Experiment [0076] In a second example, a stability experiment was conducted in which a sensor lacking a membrane and a sensor having a diffusion-limiting membrane according to the present invention were tested, simultaneously, at 37° C. The membrane-equipped sensor had a membrane prepared from the same polymer and the same crosslinker as those of the sensors of Set 2 described above in the calibration experiment. In this stability experiment, each of the sensors was placed in a PBS-buffered solution (pH 7) having a fixed glucose concentration of 30 mM, and the output current of each of the sensors was measured. The measured output currents (μA for the membrane-less sensor; nA for the membrane-equipped sensor) were plotted against time (hour), as shown in the stability graph of FIG. 4 . [0077] As shown, the stability curve for the membrane-less sensor decays rapidly over time, at a decay rate of about 4.69% μA per hour. This result indicates a lack of stability in the membrane-less sensor. By contrast, the stability curve for the membrane-equipped sensor according to the present invention shows relative constancy over time, or no appreciable decay over time, the decay rate being only about 0.06% nA per hour. This result demonstrates the considerable stability and reliability of the membrane-equipped sensors of the present invention. That is, at a glucose concentration of 30 mM, while the membrane-less sensor lost sensitivity at a rate of almost 5% per hour over a period of about 20 hours, the membrane-equipped sensor according to the present invention showed virtually no loss of sensitivity over the same period. Responsivity Experiment [0078] Ideally, the membrane of an electrochemical sensor should not impede communication between the sensing layer of the sensor and fluid or biofluid containing the analyte of interest. That is, the membrane should respond rapidly to changes in analyte concentration. [0079] In a third example, a responsivity experiment was conducted in which eight sensors having diffusion-limiting membranes according to the present invention were tested simultaneously (Set 3), all at 37° C. The sensors of Set 3 had membranes prepared from the same polymers and the same crosslinkers as those of the sensors of Set 2 described in the calibration experiment above. In this responsivity experiment, the eight sensors were placed in a PBS-buffered solution (pH 7), the glucose concentration of which was increased in a step-wise manner over time, as illustrated by the glucose concentrations shown in FIG. 5 , and the output current of each of the sensors was measured. The measured output currents (nA) were then averaged for Set 3 and plotted against time (real time, hour:minute:second), as shown in the responsivity graph of FIG. 5 . [0080] The responsivity curve for the Set 3 sensors having diffusion-limiting membranes according to the present invention has discrete steps that manic the step-wise increases in glucose concentration in a rapid fashion. As shown, the output current jumps rapidly from one plateau to the next after the glucose concentration is increased. This result demonstrates the considerable responsivity of the membrane-equipped sensors of the present invention. The responsivity of these membrane-equipped electrochemical sensors makes them ideal for analyte sensing, such as glucose sensing. Motion-Sensitivity Experiment [0081] Ideally, the membrane of an electrochemical sensor should be unaffected by motion or movement of fluid or biofluid containing the analyte of interest. This is particularly important for a sensor that is implanted in a body, such as a human body, as body movement may cause motion-associated noise and may well be quite frequent. [0082] In this fourth example, a motion-sensitivity experiment was conducted in which a sensor A lacking a membrane was tested, and separately, a sensor B having a diffusion-limiting membrane according to the present invention was tested, all at 37° C. Sensor B had a membrane prepared from the same polymer and the same crosslinker as those of the sensors of Set 2 described in the calibration experiment above. In this experiment, for each of test, the sensor was placed in a beaker containing a PBS-buffered solution (pH 7) and a magnetic stirrer. The glucose concentration of the solution was increased in a step-wise manner over time, in much the same manner as described in the responsivity experiment above, as indicated by the various mM labels in FIG. 6 . The stirrer was activated during each step-wise increase in the glucose concentration and deactivated some time thereafter, as illustrated by the “stir on” and “stir off” labels shown in FIG. 6 . This activation and deactivation of the stirrer was repeated in a cyclical manner at several levels of glucose concentration and the output current of each of the sensors was measured throughout the experiment. The measured output currents (μA for sensor A; nA for sensor B) were plotted against time (minute), as shown in the motion-sensitivity graph of FIG. 6 . [0083] As shown, the output current for the membrane-less sensor A is greatly affected by the stir versus no stir conditions over the glucose concentration range used in the experiment. By contrast, the output current for sensor B, having diffusion-limiting membranes according to the present invention, is virtually unaffected by the stir versus no stir conditions up to a glucose concentration of about 10 mM, and only slightly affected by these conditions at a glucose concentration of about 15 mM. This result demonstrates the considerable stability of the membrane-equipped sensors of the present invention in both stirred and non-stirred environments. The stability of these membrane-equipped electrochemical sensors in an environment of fluid movement makes them ideal for analyte sensing within a moving body. Sensor Reproducibility Experiment [0084] Dip-coating, or casting, of membranes is typically carried out using dipping machines, such as a DSG D1L-160 of NIMA Technology of the United Kingdom. Reproducible casting of membranes has been considered quite difficult to achieve. (Chen, T., et al., In Situ Assembled Mass - Transport Controlling Micromembranes and Their Application in Implanted Amperometric Glucose Sensors , Anal. Chem., Vol. 72, No. 16, Pp. 3757-3763 (2000).) Surprisingly, sensors of the present invention can be made quite reproducibly, as demonstrated in the experiment now described. [0085] Four batches of sensors (Batches 1-4) were prepared separately according to the present invention, by dipping the sensors in membrane solution three times using casting equipment and allowing them to cure. In each of the four batches, the membrane solutions were prepared from the polymer of Formula 4 and poly(ethylene glycol) digycidyl ether (PEDGE) crosslinker having a molecular weight of about 200 (as in Set 2 and other Sets described above) using the same procedure. The membrane solutions for Batches 1 and 2 were prepared separately from each other, and from the membrane solution used for Batches 3 and 4. The membrane solution for Batches 3 and 4 was the same, although the Batch 3 and Batch 4 sensors were dip-coated at different times using different casting equipment. That is, Batches 1, 2 and 3 were dip-coated using a non-commercial, built system and Batch 4 was dip-coated using the above-referenced DSG D1L-160 system. [0086] Calibration tests were conducted on each batch of sensors at 37° C. For each batch, the sensors were placed in PBS-buffered solution (pH 7) and the output current (nA) of each of the sensors was measured as the glucose concentration (mM) was increased. For each sensor in each of the four batches, a calibration curve based on a plot of the current output versus glucose concentration was prepared as shown in FIG. 7B (Batch 1: 5 sensors), FIG. 7C (Batch 2: 8 sensors), FIG. 7D (Batch 3: 4 sensors) and FIG. 7E (Batch 4: 4 sensors). The average slopes of the calibration curves for each batch were the following: [0087] Batch 1: Average Slope=1.10 nA/mM (CV=5%); [0088] Batch 2: Average Slope=1.27 nA/mM (CV=10%); [0089] Batch 3: Average Slope=1.15 nA/mM (CV=5%); and [0090] Batch 4: Average Slope=1.14 nA/mM (CV=7%). [0000] Further, for each batch, the current output for the sensors in the batch was averaged and plotted against glucose concentration, as shown in FIG. 7A . The average slope for Batches 1-4 was 1.17 nA/mM (CV=7.2%). [0091] The slopes of the curves within each batch and from batch-to-batch are very tightly grouped, showing considerably little variation. The results demonstrate that sensors prepared according to the present invention give quite reproducible results, both within a batch and from batch-to-batch. [0092] The foregoing examples demonstrate many of the advantages of the membranes of the present invention and the sensors employing such membranes. Particular advantages of sensors employing the membranes of the present invention include sensitivity, stability, responsivity, motion-compatibility, ease of calibration, and ease and reproducibility of manufacture. [0093] Various aspects and features of the present invention have been explained or described in relation to beliefs or theories, although it will be understood that the invention is not bound to any particular belief or theory. Various modifications, processes, as well as numerous structures to which the present invention may be applicable will be readily apparent to those of skill in the art to which the present invention is directed upon review of the specification. Although the various aspects and features of the present invention have been described with respect to various embodiments and specific examples herein, it will be understood that the invention is entitled to protection within the full scope of the appended claims.

Novel membranes comprising various polymers containing heterocyclic nitrogen groups are described. These membranes are usefully employed in electrochemical sensors, such as amperometric biosensors. More particularly, these membranes effectively regulate a flux of analyte to a measurement electrode in an electrochemical sensor, thereby improving the functioning of the electrochemical sensor over a significant range of analyte concentrations. Electrochemical sensors equipped with such membranes are also described.

FIELD OF THE INVENTION [0001] The present invention relates to any pair of computers which are connected via a one-way secure data link from one to the other such that one of them remains un-connected to the internet and the second receives data securely from the first and the second is connected to the internet. BACKGROUND [0002] Connecting computers to networks has always contained the risk that they could be penetrated with unwanted code via other computers with which they are connected. However with the advent of the internet this security problem has become extremely serious. Unlike previous networks in which a limited number of computers were connected to each other with the internet or world wide web there are so many computers participating from so many different locations that the security problems have become extreme. In order to enjoy the advantages of sharing data or work product on the internet with other users computer users such as individuals, institutions, governments and businesses connected their computers to the internet. When they did this however they later discovered that by so doing they exposed their computers to various unwanted code from other users on the internet. These forms of unwanted code can penetrate other computers using the internet and perform unwanted functions. Some of these functions include cyberattacks and espionage, cybercrime, cyberwarfare, and other forms of malicious or unwelcome or offensive activities which injure, harm or insult the user. [0003] This aweful state of affairs was never necessary. If users such as individuals, governments, institutions and businesses had been informed of the possibility of these risks they never need to have connected their computers containing vital or sensitive files or programs to the internet. It was always possible to keep their computers un-connected to the internet but enjoy the advantages of sharing data created by their computers by using a second or buffer computer which was on the internet and then transferring data from the un-connected computer to the buffer computer by a variety of secure external means such as disks or flashdrives. In this way such devices can be loaded with data from the computer un-connected to the internet and then the device connected to the un-secure buffer computer connected to the internet and then the dat loaded from the device into the buffer computer to create a file which can be distributed via the internet. By this means it has always been possible to keep certain sensitive computers un-connected to the internet and yet allow data from those computers to be shared on the internet using a buffer computer. If governments, institutions, businesses and individuals had done this then there would be little if any of the security problems which have been created. [0004] Although it's always been possible to avoid internet risks to computers by simply keeping them off the internet and using buffer computers for the internet and to distribute data thereon, there have been two problems. One problem is that this involves having two computers in two different cases. This is not as convenient as having the two computers paired into a single case. Having a single case saves room, is more modular, and allows for ease of use and portability. [0005] The second problem is the physical inconvenience of relying on external data transport systems such as flashdrives or disks to move data or files from one computer which is un-connected to the internet to the buffer computer which is connected to the internet. My invention solves these two problems by placing the pair of computers in a single case, which can be portable if desired. My invention places both computers as a pair into a single case with a single keypad and screen. The user can use the internet with the buffer computer, which contains no sensitive programs or files. When the buffer computer gets loaded down with unwanted code the user can simply wipe it clean of all code. But within the same case and using the same keypad and screen is also contained the uer's other computer in which the user maintains his vital programs and files which are not intended to be exposed to the internet. That computer has no network connections but possesses flashdrive, disk or other non-network connectors. That computer can however transport data to the buffer computer so such data can be sent or distributed on the internet by the buffer computer. My invention creates a secure on-way data link which ferries data from the un-connected computer to the buffer computer. This device cannot transfer data from the buffer computer to the un-connected computer. It is not possible for unwanted code to travel from the buffer computer to the un-connected computer. In this manner the un-connected computer. In this manner the un-connected computer remains safe from unwanted code which would otherwise penetrate it from sources via the internet. SUMMARY OF THE INVENTION [0006] The purpose of the invention is to end all security risks stemming from the internet by allowing computers to share data such as work product made on such computers but without having to be connected to the internet. [0007] My invention divides all computers into two kinds. One kind are computers in which valuable or sensitive programs and files reside. These computers are used by individuals, governments, institutions, utilities, etc., and businesses for their vital functions. These vital computers should never be connected to the internet, and are not connected to the internet in my invention. The second kind of computer are computers dedicated for internet use. These second computers store no valuable or necessary programs or files. These second computers are used to navigate the internet and use it for many purposes, however it is understood that by doing so that the computer is exposed to all manner of risks from unwanted code from malevolent sources. This second computer will accumulate unwanted code from the internet but from time to time the computer will be wiped clean of all code. [0008] My invention consists of two computers housed in one case. The computer which is connected to the internet serves the purpose of a mere browser computer which only operates internet functions. The user operates the browser computer or system using the keypad and screen attached to the computer case if the computer is a desktop or other non-laptop or portable computer, or within the computer case if the computer is a portable or laptop system design. [0009] However within the same computer case is also a second computer which is never connected to the internet. This is actually the primary computer of the user because it is a computer with substantial computing power, speed, memory storage, and other facilities such that it is suitable for use for the user's many non-internet functions. These functions are conducted by the programs and software the user needs for the computer to conduct the vital functions of the user. These functions relate to everything required of the computer and it's programs to operate the user's core needs, be the user an individual, a company, a business, a government, an institution, or any other kind of organization or individual. This primary computer possesses no network connectors, and cannot be connected to the internet. [0010] The user operates the primary computer for the user's needed functions and in so doing from time to time creates work product or files consisting of data which the user wants to use the internet for distribution to others or publication. To do this safely my invention possesses a one-way data transfer link from the primary computer to the browser computer. The user simply uses the keypad and screen shared by the two computers, or pair of systems, to operate the one-way data transfer link. The user employs the keypad and screen as controls to load data files from the primary computer into the data transfer device, or ferry. Once the intended files are loaded into the device, or ferry, the device disconnects from the primary computer and travels, or ferries, the data mechanically or electronically to the browser computer system by attaching to it and loading the intended data files into it. Once the browser computer has received the data file then the device, or ferry, disconnects from the browser computer system. Once the ferry device is disonnected from the browser computer system it is automatically wiped clean of all data. Once all data has been cleaned or purged from the ferry device then it moves mechanically or electronically back for re-attachment to the primary computer system so it may receive another load of data for transfer. [0011] In my invention the primary computer and the browser computer systems share the same screen and keypad. The user can instruct the keypad and other controls on the computer case to switch from one computer to the other. In this system the user can use the browser for the internet functions when desired and use the same keypad and screen to operate the primary computer when needed. My invention can also be configured for larger computers which cannot be fitted into a single case or use a single keypad or screen. My invention applies to all computers of any size or scale in which the primary functions of the user are operated by one or more computers which are dis-connected from the internet but use secure data transfer systems to ferry files from the secure computer system to less secure computers which are connected to the internet or other networks. DETAILED DESCRIPTION OF THE INVENTION [0012] As stated above, Computer users almost always use the same computer for internet/intranet use as for all their other sensitive or confidential uses. When they use their computers with sensitive files and data stored therein for internet/intranet use they open their sensitive files to examination, corruption or destruction by others who penetrate their computers. The common methods to counter-measure such penetrations such as the use of firewalls and software to counter access of files or disk storage are ineffective and costly. The invention claimed here solves this problem. [0013] My invention prevents anyone from accessing sensitive files or data on a computer through the internet or other external sources through structural architecture of the computer making protective measures such as anti-penetration software unnecessary. By placing within one computer chassis two independent sets of microprocessors and drives, or systems, which are structurally separate one microprocessor/drive, can be used to store sensitive files and data with no direct connection to the outside through the internet or other means. A second microprocessor/drive unconnected to the first can be used to access the internet and other vulnerable outside means. To allow the user to send data or files from the first, secured system, to the second, unsecured system, a one way data ferry is made. One way of creating a secure data ferry is to load a data drop connected to the secured system which can then be disconnected from it and then travel to the unsecured system, connect to it, and unload or download the data it conveys. Then before the data drop, or ferry, is re-connected to the secured system it can be wiped completely clean so no data from the unsecured system is transferred to the secured system. [0014] The claimed invention differs from what currently exists. Protective anti-virus, anti-spyware, anti-malware, and all other protective software and firewalls are subject to penetration and countermeasures rendering such protective measures costly, cumbersome and ineffective. The only effective way to prevent sensitive files and data from being accessed from outside sources such as the internet is to use two computers—one for sensitive data and a second for internet use. Then if the user wishes to email or send data from the first computer he must use a flashdrive, disk or other mechanism to selectively transfer particular data from the first to the second so it may be sent out. This architecture is cumbersome and expensive. As well the means for transferring data from the first to the second may be compromised unless conscious actions are taken to make sure the flashdrive or other means is not contaminated by its connection to the second computer. [0015] This invention is an improvement on what currently exists. Protective anti-virus, anti-spyware, anti-malware, and all other protective software and firewalls are subject to penetration and countermeasures rendering such protective measures costly, cumbersome and ineffective. The only effective way to prevent sensitive files and data from being accessed from outside sources such as the internet is to use two computers—one for sensitive data and a second for internet use. Then if the user wishes to email or send data from the first computer he must use a flashdrive, disk or other mechanism to selectively transfer particular data from the first to the second so it may be sent out. This architecture is cumbersome and expensive. As well the means for transferring data from the first to the second may be compromised unless conscious actions are taken to make sure the flashdrive or other means is not contaminated by its connection to the second computer. [0016] Software to provide counter-measures to malware, spyware, or other unwanted penetrating code are expensive, troublesome to install and update, and have vulnerabilities rendering them ineffective. The alternative of using two independent computers requires that two different keyboards and screens be used which takes up unnecessary space and is inconvenient relative to using a single keyboard and screen. Then the means employed of transferring data from the non-internet/intranet computer to the one connected to the outside must be consciously wiped clean or disposed of so and new and uncontaminated device may be safely used. [0017] By placing two independent sets, or systems, of microprocessors and hard drives into one computer chassis, and creating a secure data ferry which is automatically wiped clean and sanitized after each use there are not two different computer keyboards, screens, etc. to be negotiated. As well because the data ferry is automatically wiped clean and sanitized there is no risk that its prior connection to the internet connected unsecured system will contaminate the secured system which contains the sensitive data. [0018] The Version of the Invention Discussed Here Includes: 1. secured drive/processor system with accompanying software 2. unsecured drive/processor system with accompanying software 3. data ferry 4. data ferry conveyance mechanism 5. data ferry sanitation device with accompanying software [0024] Relationship Between the Components: [0025] Number 3 the DATA FERRY is used to store data from the Number 1 SECURED SYSTEM DRIVE/PROCESSOR/ACCOMPANYING SOFTWARE by connecting to it and receiving data from it. Once Number 3 the DATA FERRY has received the data it disconnects from Number 1 the SECURED SYSTEM DRIVE/PROCESSOR/ACCOMPANYING SOFTWARE and Number 4 the DATA FERRY CONVEYANCE MECHANISM physically or electronically moves Number 3 the DATA FERRY and/or it's contained stored data to connect to Number 2 the UNSECURED SYSTEM DRIVE/PROCESSOR/ACCOMPANYING SOFTWARE where it is available for attachment to emails or other means of transference out of the computer. Once Number 3 the DATA FERRY has unloaded its data to Number 2 the UNSECURED DRIVE/PROCESSOR/ACCOMPANYING SOFTWARE it is disconnected from Number 2 the UNSECURED SYSTEM DRIVE/PROCESSOR/ACCOMPANYING SOFTWARE and then is automatically wiped clean of all data of any kind Number 5 the DATA FERRY SANITATION DEVICE WITH ACCOMPANYING SOFTWARE. [0026] How the Invention Works: [0027] The UNSECURED SYSTEM DRIVE/PROCESSOR/ACCOMPANYING SOFTWARE is a data system which can perform any of the applications desired by a computer except for connection to, and exporting data to, the world outside of itself. For that reason it never needs to be cleaned because it will never be accessed or penetrated from outside. When the user wishes to take data from it and send it to others he commands the DATA FERRY [which has been previously cleaned] to attach itself mechanically or electronically to the SECURED SYSTEM DRIVE/PROCESSOR/ACCOMPANYING SOFTWARE and the latter device system loads the DATA FERRY with the desired data. Once the DATA FERRY is loaded with data it disconnects from the SECURED SYSTEM DRIVE/PROCESSOR/ACCOMPANYING SOFTWARE and the DATA FERRY CONVEYANCE MECHANISM physically/mechanically or electronically conveys the DATA FERRY and/or its data to connect to the UNSECURED SYSTEM DRIVE/PROCESSOR/ACCOMPANYING SOFTWARE. Once the UNSECURED SYSTEM DRIVE/PROCESSOR/ACCOMPANYING SOFTWARE has received the data it may use the data for emailing or other transferal functions via internet or intranet or telephonic connection or any other connectivity function which the computer user wishes to perform. By performing this function this way, by this system, the computer user is only exposing the UNSECURED SYSTEM DRIVE/PROCESSOR/ACCOMPANYING SOFTWARE to penetration from outside and corruption or examination of data therein. Only the UNSECURED SYSTEM DRIVE/PROCESSOR/ACCOMPANYING SOFTWARE need be cleaned in order to purge it of unwanted code while the SECURED SYSTEM DRIVE/PROCESSOR/ACCOMPANYING SOFTWARE remains pristine. To assure that the SECURED SYSTEM DRIVE/PROCESSOR/ACCOMPANYING SOFTWARE remains pristine after the DATA FERRY disconnects from the UNSECURED SYSTEM DRIVE/PROCESSOR/ACCOMPANYING SOFTWARE the DATA FERRY is wiped clean of any data by the DATA FERRY SANITATION DEVICE WITH ACCOMPANYING SOFTWARE. [0028] How to Make the Invention: [0029] Take the internal mechanisms of two computers: their hard drives and accompanying processors, and assemble them into two independent computing systems installed into a single computer chassis with a single keyboard and screen. Then give each of the two systems of drives and processors its own software so that they can be independently operated from the same keyboard, mouse or screen. Create a data ferry by installing a data memory device between the two systems, and construct a mechanism for the ferry and/or its contained data to be moved or conveyed so as to be connected and disconnected between the two systems. Make sure that the memory device, or data ferry, cannot be connected to both systems at the same time. Design the conveyance for the memory device, or data ferry, between the two systems so that after it has been disconnected from the unsecured system into which it's data is transferred that it automatically is wiped clean of all data by a device appropriate to do so which itself cannot be corrupted by any data the memory device may contain. [0030] The two systems with their accompanying software are necessary as is the data ferry/memory device and its conveyance mechanism and the sanitizing device which wipes it clean before it is re-connected to the secure system. None of these parts are optional except for the data ferry sanitizing device if the data ferry is constituted such that it cannot receive data from the unsecured system or the unsecured system is constituted in such a way that it cannot transfer data to the data ferry. [0031] The data ferry may itself be physically moved between the secured and unsecured systems by the conveyance mechanism. However the same function may be conducted by the data ferry remaining stationary and the data it conveys being transferred to it and then to the unsecured system by means of electrical gates which can be securely opened and shut. For this system to work these gates like the data ferry sanitizing device must be completely independent from the unsecured system, or corruption of the system could be used to control the gates such that they could allow data to pass from the unsecured system via the data ferry to the secured system. No sanitizing device for the data ferry is required if it is constituted to not be able to receive data from the unsecured system or the unsecured system is constituted so it cannot transfer data to the data ferry. [0032] How to Use the Invention: [0033] The user or operator would shift back and forth between the two unconnected and independent systems depending on the task performed. When the user wishes the convenience of using a system connected to the internet for purposes which are not sensitive and require no security he may use the unsecured system. He may keep few software packages on the unsecured system and clean it of unwanted code from time to time by wiping its hard drive and other components clean without having to reload many software programs. However when the user wishes to perform tasks for which security is desired and wishes to store software programs which cannot be easily unloaded and reloaded when a hard drive, etc. is cleaned, then the user can use the secured system. Whenever the user wishes to load or transfer data into the secure system he can do so through flash drives or disks for which he maintains discretion and accounting/management. Otherwise there is no way that the secured system can be penetrated or its codes or data accessed by unintended parties. Then when the user wishes to transport data from the secured system to parties outside of his computer he can instruct the data ferry conveyance system to connect the clean data ferry to the secure system so the desired data can be loaded into it. Once the data is loaded into the data ferry it [or its data] is conveyed to the unsecured system, and the data is transferred to it. When the data has been transferred to the unsecured system the data ferry disconnects automatically from the unsecured system and is wiped clean of all data by the sanitizing device. The user can use the transferred data in the unsecured system for transmittal to outside parties via email or any other means the user can instruct the unsecured system to do. [0034] Additionally: The use of a data ferry as described can be used to transfer data between a secured device and an unsecured device although the devices may not be computers but other forms of electronic devices uses data or signals or information such as radio transmitters or receivers or telephones, etc. DRAWING DESCRIPTION [0035] FIG. 1 : is a schematic diagram of the invention. DESCRIPTION LIST [0000] 10 : is the overall structural data ferry system invention. 12 : is the monitor. 14 : is the keypad or keyboard. 16 : is the computer case. 18 : is the secured system. 20 : is the unsecured system. 22 : is the secured hard drive/CPU/GPU/software. 24 : is the unsecured hard drive/CPU/GPU/software. 26 : is the data ferry. 28 : is the data ferry conveyance mechanism. 30 : is the data ferry sanitation device. 32 : is the wireless card. 34 : is the network connector. 36 : USB port. 38 : is disk burner/reader. 40 : is the data link/route from keyboard to computer. 42 : is the secured system/unsecured system data router (keypad data). 44 : is the unsecured system data route from data router (keypad data). 46 : is the secured system data route from data router (keypad data). 48 : is the data link/route from computer to monitor. 50 : is the monitor data node. 52 : is the unsecured system data route to data node. 54 : is the secured system data route to data node. 56 : indicates direction of current.

The present invention relates to a system allowing computers to be un-connected to the internet or networks while still allowing computers to share data on networks. By creating a one-way secure data link from a primary computer not connected to a network to a second, buffer computer which is connected to networks, the primary computer can distribute data on networks without the risks of being connected to networks.

FIELD OF THE INVENTION AND RELATED ART [0001] The present invention relates to wrapping material for wrapping an object, a wrapping method for wrapping an object with the wrapping material in order to package the object, and a manufacturing method for the wrapping material used for packaging an object. [0002] As for the wrapping material such as the above described one, the wrapping material disclosed in the following publications has been known, which comprises: a cushioning medium storage portion for holding cushioning medium; a check valve which allows the cushioning medium to move to the cushioning medium storage portion, but prevents the cushioning medium from flowing backward from the storage portion; and a guiding portion for guiding the cushioning medium into the cushioning medium storage portion, through the check valve, from outside the wrapping material (FIG. 2 of U.S. Pat. No. 5,427,830, and FIG. 1 of Japanese Laid-open U.M. Application 1-164142). [0003] In the case of the wrapping materials in accordance with the above described prior art, however, there is a concern that as the wrapping material is stored for a long time in an environment which is high in temperature and humidity, or an environment low in pressure, the cushioning medium in the cushioning medium storage portion of the wrapping material increases in volume, increasing thereby the internal pressure of the storage portion. The increased internal pressure in the cushioning medium storage portion forces the cushioning medium to flow backward through the check valve, gradually reducing the amount of the cushioning medium in the storage portion. As the amount of the cushioning medium in the storage portion reduces, the shock absorbing effect of the wrapping material is reduced. The present invention was made to solve this problem. SUMMARY OF THE INVENTION [0004] The primary object of the present invention is to provide a wrapping material reliably protecting an object in a carton, a method for packing an object, and a manufacturing method for manufacturing the packing material. [0005] Another object of the present invention is to provide a wrapping material capable of protecting an object from external shocks, a wrapping method for wrapping an object with the wrapping material, and a manufacturing method for the wrapping material. [0006] Another object of the present invention is to provide a wrapping material from which the cushioning medium therein does not leak even if the cushioning medium therein flows backward due to the changes in ambience a wrapping method for wrapping an object with the wrapping material, and a manufacturing method for the wrapping material. [0007] Another object of the present invention is to provide a wrapping material superior in the efficiency with which cushioning medium can injected into the wrapping material a wrapping method for wrapping an object with the wrapping material, and a manufacturing method for the wrapping material. [0008] Another object of the present invention is to provide a wrapping material which may be injected with cushioning medium after the shipment of the wrapping material to its final destination, being therefore superior in shipment efficiency, a wrapping method for wrapping an object with the wrapping material, and a manufacturing method for the wrapping material. [0009] Another object of the present invention is to provide a wrapping material comprising a single or plurality of cushioning medium storage portions for holding cushioning medium; a single or plurality of check valves for preventing the cushioning medium from flowing backward from the cushioning medium storage portion while allowing the cushioning medium to flow toward the cushioning medium storage portion; a single or plurality of guiding portions for guiding the cushioning medium from outside the wrapping material into the cushioning medium storage portion through the check valve, in order to inflate the cushioning medium storage portion; a sealing area, which is located on the upstream of the check valve, in terms of the direction in which the cushioning medium is guided to the check valve through the guiding portion, and across which the guiding portions are sealed after the injection of the cushioning medium into the cushioning medium storage portion, in order to prevent the cushioning medium having flowed backward from the cushioning medium storage portion into the guiding portion through the check valve, from leaking out of the wrapping material through the guiding portion. [0010] Another object of the present invention is to provide a wrapping method, in which when wrapping an object with a wrapping material comprising a sealing area which is located on the upstream of the check valve, in terms of the direction in which the cushioning medium is guided to the check valve through the guiding portion, and across which the guiding portions are sealed after the injection of the cushioning medium into the cushioning medium storage portion, in order to prevent the cushioning medium having flowed backward from the cushioning medium storage portion into the guiding portion through the check valve, from leaking out of the wrapping material through the guiding portion, the wrapping material is sealed across said sealing area after the object is wrapped with the wrapping material and the cushioning medium is injected into the cushioning medium storage portions. [0011] Another object of the prevent invention is to provide a wrapping material manufacturing method comprising a cushioning medium guiding portion forming step for forming a single or plurality of guiding portions which are located on the upstream of the check valve, in terms of the direction in which the cushioning medium is guided toward the check valve through the guiding portion, and which have a sealing area across which the guiding portion is to be sealed is after the injection of the cushioning medium into the cushioning medium storage portions, in order to prevent the cushioning medium having flowed backward from the cushioning medium storage portion into the guiding portion through the check valve, from leaking out of the wrapping material through the guiding portion. [0012] Another object of the present invention is to provide a unit which is removably mountable in the main assembly of an electrophotographic image forming apparatus, and can be wrapped, at least when it is transported, with a wrapping material comprising: a single or plurality of cushioning medium storage portions for holding cushioning medium; a single or plurality of check valves for preventing the cushioning medium from flowing backward from the cushioning medium storage portion while allowing the cushioning medium to flow toward the cushioning medium storage portion; a single or plurality of guiding portions for guiding the cushioning medium from outside the wrapping material into the cushioning medium storage portion through the check valve, in order to inflate the cushioning medium storage portion; a sealing area which is located on the upstream of the check valve, in terms of the direction in which the cushioning medium is guided to the check valve through the guiding portion, and across which the guiding portions are sealed after the injection of the cushioning medium into the cushioning medium storage portion, in order to prevent the cushioning medium having flowed backward from the cushioning medium storage portion into the guiding portion through the check valve, from leaking out of the wrapping material through the guiding portion. [0013] These and other objects, features, and advantages of the present invention will become more apparent upon consideration of the following description of the preferred embodiments of the present invention, taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0014] [0014]FIG. 1 is a plan view of the wrapping material in accordance with the present invention. [0015] [0015]FIG. 2 is a sectional view of the wrapping material in accordance with the present invention. [0016] [0016]FIG. 3 is a perspective view of the partially unrolled roll of the wrapping material in the preferred embodiment of the present invention, showing one of the steps for wrapping a cartridge with the wrapping material in accordance with the present invention. [0017] [0017]FIG. 4 is a perspective view of the wrapping material in accordance with the present invention, showing another step for wrapping a cartridge with the wrapping material in accordance with the present invention. [0018] [0018]FIG. 5 is a plan view of the wrapping material in accordance with the present invention, showing another step for wrapping a cartridge with the wrapping material in accordance with the present invention. [0019] [0019]FIG. 6 is a plan view of the wrapping material in accordance with the present invention, showing another step for wrapping a cartridge with the wrapping material in accordance with the present invention. [0020] [0020]FIG. 7 is a perspective view of the wrapping material in accordance with the present invention, showing another step for wrapping a cartridge with the wrapping material in accordance with the present invention (cartridge insertion step). [0021] [0021]FIG. 8 is a perspective view of the wrapping material in accordance with the present invention, showing another step for wrapping a cartridge with the wrapping material in accordance with the present invention (cartridge insertion step). [0022] [0022]FIG. 9 is a perspective view of the wrapping material in accordance with the present invention, showing another step for wrapping a cartridge with the wrapping material in accordance with the present invention (after sealing of wrapping material). [0023] [0023]FIG. 10 is a perspective view of the wrapping material in accordance with the present invention, showing another step for wrapping a cartridge with the wrapping material in accordance with the present invention (after sealing of wrapping material). [0024] [0024]FIG. 11 is a sectional view of one of the cushioning medium storage portions of the wrapping material, showing the state of storage portion, in which the internal pressure of the storage portion is high. [0025] [0025]FIG. 12 is a perspective view of a wrapping material in accordance with prior art, showing how air leaks from the cushioning medium storage portions. [0026] [0026]FIG. 13 is a perspective view of the wrapping material in accordance with the present invention. [0027] [0027]FIG. 14 is a drawing of the wrapping material in accordance with the present invention; FIG. 14( a ) is a plan view (reverse side) thereof; FIG. 14( b ) is plan view (reverse side) thereof, showing the tearing of the wrapping material, which was started from the notch; and FIG. 14( c ) is a plan view (reverse side) of the wrapping material, which has been torn across the area with no tear guiding seams. [0028] [0028]FIG. 15 is a perspective view of the wrapping material in accordance with the present invention, showing how the wrapping material is torn from the notch to unseal the wrapping material. [0029] [0029]FIG. 16 is a perspective view or the wrapping material in accordance with the present invention, showing how the wrapping material was torn from the notch to unseal the wrapping material. [0030] [0030]FIG. 17 is a plan view of another wrapping material in accordance with the present invention. [0031] [0031]FIG. 18 is a perspective view of the wrapping material in accordance with the present invention. [0032] [0032]FIG. 19 is a sectional view of the wrapping material in accordance with the present invention; FIG. 19( a ) is a sectional view of combination of the wrapping material in accordance with the present invention, and the object wrapped with the wrapping material; and FIG. 19( b ) is a sectional view of the combination of the wrapping material which does not have the second guiding portion, and the cartridge wrapped with the wrapping material. [0033] [0033]FIG. 20 is a plan view of another wrapping material in accordance with the present invention. [0034] [0034]FIG. 21 is a perspective view of the wrapping material in accordance with the present invention. [0035] [0035]FIG. 22 is a sectional view of the wrapping material in accordance of the present invention; FIG. 22( a ) is a sectional view of the combination of the wrapping material and the object wrapped with the wrapping material, and FIG. 22( b ) is a sectional view of the combination of the wrapping material having no cushioning medium storage portions uninjectable with air, and the object wrapped by the wrapping material. [0036] [0036]FIG. 23 is a plan view of the tear guiding portions of the wrapping material in accordance with the present invention; FIGS. 23 ( a ), 23 ( b ), 23 ( c ), and 23 ( d ) show various patterns of the tear guiding portions, one for one. [0037] [0037]FIG. 24 is a perspective view of the preferred packaging carton in accordance with the present invention. [0038] [0038]FIG. 25 is a perspective view of the preferred packaging carton in accordance with the present invention. [0039] [0039]FIG. 26 is a perspective view of the preferred packaging carton in accordance with the present invention. [0040] [0040]FIG. 27 is a perspective view of the packaging carton in accordance with the prior art. [0041] [0041]FIG. 28 is a perspective view of the packaging carton in accordance with the prior art. [0042] [0042]FIG. 29 is a sectional view of the check valve, and its adjacencies, of one of the cushioning medium storage portions of the wrapping material in accordance with the present invention. [0043] [0043]FIG. 30 is a plan view of the check valve, and its adjacencies, of one of the cushioning medium storage portions of the wrapping material in accordance with the present invention. [0044] [0044]FIG. 31 is a development of the packaging carton in accordance with the prior art. [0045] [0045]FIG. 32 is a development of the packaging carton in accordance with the present invention. [0046] [0046]FIG. 33 is a perspective view of a transportation pallet, and 180 cartons, in accordance with the prior art, loaded on the pallet. [0047] [0047]FIG. 34 is a perspective view of a transportation pallet, and 203 cartons, in accordance with the present invention, loaded on the pallet. [0048] [0048]FIG. 35 is a sectional view of the combination of the wrapping material in accordance with the present invention, and the cartridge wrapped therewith. [0049] [0049]FIG. 36 is a sectional view of the combination of the wrapping material which does not have the second guiding portion, and the cartridge wrapped therewith. [0050] [0050]FIG. 37 is a sectional view of the combination of the wrapping material in accordance with the present invention, and the cartridge wrapped therewith. [0051] [0051]FIG. 38 is a sectional view of the combination of the wrapping material lacking the cushioning medium storage portions uninjectable with air, and the cartridge wrapped therewith. [0052] [0052]FIG. 39 is a perspective view of the packaging supplies in accordance with the prior art. [0053] [0053]FIG. 40 is a perspective view of the packaging carton in accordance with the prior art, and the packaging supplies therein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0054] Next, the preferred embodiments of the present invention will be described with reference to the appended drawings. [0055] Embodiment 1 [0056] (Structure of Wrapping Material) [0057] Hereinafter, the first embodiment of the present invention will be described with reference to the appended drawings. [0058] Referring to FIGS. 1 and 2, a wrapping material S 1 , in the form of a sheet, in accordance with the present invention is a laminar sheet formed by thermally welding two pieces 1 and 2 of flexible plastic film. The lines (welding seams) designated by the numbers 6 , 8 , 9 , and 10 are the lines along which the two pieces of flexible plastic film were thermally welded. The wrapping material S 1 is provided with a plurality of parallel cushioning medium storage portions 3 in which air as cushioning medium can be stored. Each cushioning medium storage portion 3 is created by thermally welding the first and second films 1 and 2 along the welding line 10 . It is shaped to be long and narrow as shown in FIG. 1. Incidentally, the flexible films 1 and 2 in this embodiment are laminar, having three layers. More specifically, they comprise a nylon layer, a polyethylene layer, and a polypropylene layer, with the nylon layer sandwiched between the polyethylene and polypropylene layers. The nylon layer is virtually imperviable by the cushioning medium, and the polyethylene and polypropylene are easier to thermally weld. [0059] The cushioning medium storage portion 3 is provided with a check valve 4 , which is located at one of the lengthwise ends of the cushioning medium storage 3 . The check valve 4 allows air to pass the check valve 4 in the direction to be filled into the cushioning medium storage portion 3 . Referring to FIG. 2, after the filling of air into the cushioning medium storage portion 3 , the pressure generated by is the air in the cushioning medium storage portion 3 is used by the check valve 4 to prevent the air in the cushioning medium storage portion 3 from flowing backward. The detailed structure of the check valve 4 is shown in FIGS. 29 and 30. The check valve 4 is manufactured through the following procedure. The film 1 is provided with the top portion of the check valve 4 , which is temporarily attached to the portion 1 a of the film 1 . The film 2 is provided with the bottom portion 4 b of the check valve 4 , and the sealing portion 4 c of the check valve 4 , which also are temporarily attached to the film 2 . The films 1 and 2 are thermally welded to each other along the lines 6 , 8 , 9 , and 10 , as shown in FIG. 1. The sealing member 4 c is formed of a material which does not melt at the temperature level at which the two films 1 and 2 are welded to each other along the line 8 . The lines 9 and 10 extend in parallel in the lengthwise direction of the cushioning medium storage portion 3 . The lines 6 and 8 extend in the direction perpendicular to the lengthwise direction of the cushioning medium storage portion 3 . The line 6 is located at the opposite lengthwise end of the wrapping material S 1 from the area 8 . [0060] Referring to FIG. 30, the two films 1 and 2 are welded along the portions 8 b and 8 c , of the line 8 (welding seam), but not across the portion 8 a which corresponds in position to the sealing member 4 c , allowing air to be guided into the cushioning medium storage portion 3 in the direction indicated by an arrow mark. The lengthwise direction of the cushioning medium storage portion 3 is virtually the same as the direction in which air is allowed to pass through the check valve 4 , making it possible for air to be efficiently guided into the cushioning medium storage portion 3 . [0061] The wrapping material S 1 is also provided with a plurality of guiding portions 5 through which medium (air) is guided into the plurality of cushioning medium storage portions 3 through the plurality of check valves 4 from outside, in order to inflate the cushioning medium storage portions 3 , one for one. The outward end of each guiding portion 5 constitutes an inlet 11 through which air is injected into the cushioning medium storage portion 3 . The guiding portions 5 are also created by welding the films 1 and 2 to each other. The line along which the two films 1 and 2 are welded is the line 7 . Referring to FIG. 6, the width W1 of each inlet 11 is less than the width W2 of the joint between the guiding portion 5 , and the check valve 4 located on the downstream side of the guiding portion 5 . In terms of the above described medium injection direction. Further, the plurality of inlets 11 are positioned side by side, making it possible to reduce, in size, the outlet portion (unshown) of an injecting apparatus, for injecting air into all the cushioning medium storage portions 3 all at once through their inlets 11 . With the provision of the above described structural arrangement, the direction in which air is injected into the plurality of guiding portions 5 is virtually the same as the direction in which air is guided into the cushioning medium storage portions 3 through the check valves 4 , one for one. Therefore, air can be efficiently injected into the plurality of cushioning medium storage portions 3 . Further, each of the lines 7 (welding seams), which extends from the joint between the check valve 4 and guiding portion 5 to the inlet 11 , is bent toward the inlet 11 . [0062] The area 48 of the wrapping material S 1 is the area across which the films 1 and 2 are welded to each other to seal the guiding portions 5 in order to prevent the air having flowed backward from the cushioning medium storage portions 3 into the guiding portions 5 through the check valves 4 , from leaking out of the wrapping material S 1 . The wrapping material S 1 is sealed across this area 48 by a dedicated welding apparatus (unshown) after the injection of air into the cushioning medium storage portions 3 . [0063] Each of the cushioning medium storage portions 3 is provided with a pair of portions 3 b , which are narrower, in terms of the direction perpendicular to the lengthwise direction of the cushioning medium storage portion 3 , than the rest of the cushioning medium storage portion 3 , and which are located at predetermined locations, one for one, in terms of the lengthwise direction of the cushioning medium storage portion 3 . This narrow portion 3 b of the cushioning medium storage portion 3 is provided to reduce the amount of the pressure to which an object wrapped with the wrapping material S 1 is subjected after the injection of cushioning medium into the cushioning medium storage portion 3 . More specifically, the wrapping material S 1 is structured so that its narrow portions 3 b correspond in position to the portions of an object to be wrapped, which could be damaged (deformed) by the contact pressure between the wrapping material S 1 and the object. Referring to FIG. 6, the width W4 of the narrow portion 3 b is less than the width W3 of the other portions of the cushioning medium storage portion 3 . In other words, the cross section of the narrow portion 3 b of the cushioning medium storage portion 3 is less than that of the other portions of the cushioning medium storage portion 3 . Also referring to FIG. 6, the narrow portion 3 b can be formed by widening, in the direction perpendicular to the lengthwise direction of the cushioning medium storage portion 3 , the welding seam 23 by which the films 1 and 2 are welded to each other than the welding seam 10 . The welding seam 23 is also formed by an dedicated welding apparatus (unshown). [0064] The above described structure of the wrapping material S 1 can be summarized as follows. [0065] The wrapping material S 1 is characterized in that it comprises: the cushioning medium storage portions 3 for storing the cushioning medium; the check valves 4 which allow the cushioning medium to pass through them into the cushioning medium storage portions 3 , one for one, but prevent the cushioning medium from flowing backward from the cushioning medium storage portions 3 through them; the guiding portions 5 for guiding the cushioning medium into the cushioning medium storage portions 3 , one for one, through the check valves 4 from outside the wrapping material S 1 , in order to inflate the cushioning medium storage portions 3 ; the area 48 which is positioned upstream, in terms of the direction in which the cushioning medium is guided through the guiding portions 5 to the check valves 4 , one for one, of the check valves 4 , in order to prevent the portion of the cushioning medium having flowed backward from the cushioning medium storage portions 3 into the guiding portions 5 through the check valves 4 , from leaking out of the wrapping material S 1 , and across which the wrapping material S 1 is sealed after the cushioning medium storage portions 3 are filled with the cushioning medium. [0066] Each cushioning medium storage portion 3 is shaped to be long and narrow, and its lengthwise direction is virtually the same as the direction in which the cushioning medium flows through the check valve 4 . [0067] Each guiding portion 5 has the inlet 11 , which is located at the outward end of the guiding portion 5 , and through which the cushioning medium is injected into the cushioning medium storage portion 3 from outside the wrapping material S 1 . The direction in which the cushioning medium is injected into the cushioning medium storage portion 3 is roughly the same as the direction in which the cushioning medium flows into the cushioning medium storage portion 3 through the check valve 4 . [0068] The plurality of cushioning medium storage portions 3 are positioned parallel to each other. The check valves 4 are provided one for each of the plurality of cushioning medium storage portions 3 , being independent from each other, and so are the guiding portions 5 . [0069] The area 48 is located so that the plurality of guiding portions 3 become roughly the same in the amount by which the cushioning medium can be stored in each of the guiding portions 5 after the sealing of the wrapping material S 1 across the area 48 . [0070] Each of the plurality of guiding portions 5 is provided with the inlet 11 , which is positioned at the upstream end of the guiding portion 5 , in terms of the cushioning medium injection direction, to inject the cushioning medium into the cushioning medium storage portion 3 from outside the wrapping material S 1 . The width W1 of the inlet 11 is less than the width W2 of the joint between the guiding portion 5 , and the check valve 4 located downstream of the guiding portion 5 in terms of the cushioning medium injection direction. Since the width W1 of the inlet 11 is less than the width W2 of the joint, and the plurality of inlets 11 are positioned immediately next to each other, it is possible to reduce in size the apparatus (unshown) for injecting air into the wrapping material S 1 through the plurality of inlets 11 . The width W1 of each inlet 11 is in the range of 10-15 mm, and the width W2 of each joint is in the range of 25-30 mm. [0071] Further, in order to reduce the pressure which is applied to an object wrapped with the wrapping material S 1 , after the injection of the cushioning medium into the cushioning medium storage portions 3 , each cushioning medium storage portion 3 is provided with the portions 3 b which are narrower, in terms of the direction perpendicular to the lengthwise direction of the cushioning medium storage portion 3 , than the other portions of the cushioning medium storage portion 3 , and which are positioned at the predetermined locations, one for one, in terms of the lengthwise direction of the cushioning medium storage portion 3 . [0072] Generally, a wrapping material, such as the wrapping material S 1 in this embodiment, having a plurality of cushioning medium storage portions 3 , a plurality of check valves 4 , and a plurality of guiding portions 5 , comes in the form of a roll comprising a substantial number of wrapping materials S 1 . In order to obtain a wrapping material suitable in size for properly wrapping a given object, a single or plural wrapping materials S 1 are cut from the roll of wrapping material. The obtained single or plural units of the wrapping materials S 1 are process as described above to properly wrap the object. Next, one of the methods for wrapping an object with the above described wrapping material, will be described. [0073] (Wrapping Method which Uses Wrapping Material in Accordance with Present Invention) [0074] Referring to FIGS. 3-9, the method for packaging a process cartridge removably mountable in the main assembly of an electrophotographic image forming apparatus, with the use of the wrapping material S will be described. Incidentally, an electrophotographic image forming apparatus means an apparatus for forming an image on recording medium with the use of an electrophotographic image forming method. As examples of an electrophotographic image forming apparatus, there are an electrophotographic copying machine, an electrophotographic printer (for example, laser beam printer, LED printer, etc.) a facsimileing machine, a wordprocessor, etc. A process cartridge means a cartridge in which a minimum of one processing means among a charging means, a developing means, and a cleaning means, are integrally disposed, along with an electrophotographic photosensitive member, and which is removably mountable in the main assembly of an image forming apparatus. [0075] (1) Cutting of Wrapping Material from Wrapping Material Roll (FIG. 3) [0076] The long of roll S of sheet made up of a substantial number of wrapping materials comprising: a plurality of the cushioning medium storage portions 3 , plurality of check valves 4 , and plurality of guiding portions 5 , and connected by lengthwise edges, is to be cut to a piece having the length necessary to properly wrap a process cartridge 35 . In this embodiment, the roll is cut with a pair of scissors K 1 . However, it may be cut with a cutter, or a dedicated cutting apparatus. The wrapping material roll S has a metallic core K 2 , which is in the center of the roll S, making it easier to pull out the wrapping material Sheet S to cut it. Further, the provision of the metallic core K 2 makes it easier to set the roll S of sheet of wrapping materials in a predetermined position, in an automatic cutting apparatus or the like. [0077] (2) Process for Turning Wrapping Material into Pouch (FIGS. 4-6) [0078] The wrapping material S 1 separated from the roll S is to be folded in half roughly at the center thereof in terms of the lengthwise direction of the cushioning medium storage portion 3 , so that the downstream end 53 of the wrapping material S 1 meets the area of the wrapping material S 1 shown in FIG. 5. [0079] Then, one half of the wrapping material S 1 is to be welded to the other half along the edge areas (lines 12 and 13 ) to form the wrapping material S 1 into a pouch having an opening at one or the lengthwise ends. Incidentally, the lines 12 and 13 (welding seams) extend in the lengthwise direction of the cushioning medium storage portion 3 . [0080] Although the following will be described later in detail, the wrapping material S 1 is provided with a small notch 15 , which is provided to make it easier to tear the wrapping material S 1 when removing an object from the pouch made of the wrapping material S 1 . The notch 15 is also the portion of the wrapping material S 1 , from which the wrapping material can be easily torn to create openings for cushioning medium storage portions, one for one, in order to release the cushioning medium in the cushioning medium storage portions. [0081] In this embodiment, the wrapping material S 1 was formed into a pouch, which was open at one of the lengthwise ends. However, the wrapping material S 1 may be formed into a pouch, which is open at one or both ends in terms of the direction perpendicular to the lengthwise direction of the cushioning medium storage portion 3 . Moreover, it may be formed in to a pouch, which is open at one of the lengthwise ends, as well as one of the ends in terms of the direction perpendicular to the lengthwise end of the cushioning medium storage portion 3 . [0082] (3) Insertion of Object (Cartridge 35 ) into Pouch Formed of Wrapping Material S 1 (FIG. 5) [0083] Referring to FIG. 5, the cartridge 35 , an object to be packaged, is to be Inserted into the pouch formed of wrapping material S 1 (which hereafter may be referred to as “pouch S 1 ”) through the opening 18 located at one of the lengthwise ends thereof. In other words, the cartridge 35 is inserted so that the lengthwise direction of the cartridge 35 becomes virtually parallel to the lengthwise direction of the cushioning medium storage portion 3 . Thereafter, the front and reverse sides of the pouch S 1 are welded to each other across the line 19 (pouch S 1 is thermally sealed), to seal the inlet 18 in order to airtightly seal the cartridge 35 in the pouch S 1 . The line 19 (welding scam) extends in the direction perpendicular to the lengthwise direction of the cushioning medium storage portion 3 . In other words, the line 19 (welding seam) extends in the direction parallel to the shorter edges of the cartridge 35 . It is located closer to the inlet 11 than the line 18 (welding seam) and check valve 4 . However, across each of the sections 19 a of the line 19 , the front and reverse sides of the pouch S 1 are not welded to each other, because the aforementioned sealing member 4 c extends across the section 19 a , as shown in FIG. 30. Therefore, air can be injected in the direction indicated by an arrow mark, through the check valves 4 , into the cushioning medium storage portions 3 of the pouch S 1 in which the cartridge 35 has been airtightly sealed. [0084] (4) Injection of Cushioning Medium (FIGS. 5 and 9) [0085] The cushioning medium, which in this embodiment is air, is injected into each of the cushioning medium storage portions 3 of the pouch S 1 through the inlet 11 , guiding portion 5 , and check valve 4 of the cushioning medium storage portion 3 . The reason for injecting air after the sealing of the cartridge 35 in the pouch S is to prevent static electricity from being induced between the cartridge 35 and the film 1 or 2 when the cartridge 35 is inserted. More specifically, it is for preventing the object (cartridge 35 ) from being adversely affected by the static electricity which will be induced if an object (cartridge 35 ) is inserted into the pouch S 1 after the injection of air into the cushioning medium storage portions 3 of the pouch S 1 . In addition, the wrapping method of injecting air after the insertion of the cartridge 35 is superior in operational efficiency than the wrapping method of injecting air before the insertion of the cartridge 35 . More specifically, referring to FIG. 9, as air is injected into the pouch S 1 after the insertion of the cartridge 35 into the pouch S 1 , pressure is gradually built up in the cushioning medium storage portions 3 , and this pressure works in the direction to tension the guiding portions 5 in the direction to flatten the guiding portions 5 . As a result, the air in the guiding portions 5 is forced out of the guiding portions 5 through the inlets 11 in the direction indicated by arrow marks. Incidentally, the cushioning medium injected into the cushioning medium storage portions of the pouch S 1 in this embodiment is air. However, the selection of the cushioning medium does not need to be limited to air. For example, nitrogen gas, oxygen gas, or the like, may be used. In particular, nitrogen gas is less likely to leak from the cushioning medium storage portion formed of plastic film or the like, because the molecular weight of nitrogen is relatively large. Further, there will be no problem even if a fluid substance such as liquid is used as the cushioning medium. [0086] (5) Sealing of Cushioning Medium Guiding Portion (Thermal Sealing) [0087] Next, referring to FIG. 10, the pouch S 1 is sealed across the portion of the area (sealing range) 48 , which is on the inlet 11 side of the welding seam 8 in terms of the lengthwise direction of the cushioning medium storage portion 3 . More specifically, the pouch S 1 is thermally sealed across the area in which the cushion medium guiding portions 5 are present, more specifically, along the line 50 , which makes the cushioning medium capacity of the portion of the cushioning medium guiding portion 5 , between the welding seam 8 and line 50 , after the sealing of the pouch S 1 along the line 50 , equal to 5% −10% of the total cushioning medium capacity of the cushioning medium storage portion 3 . The line 50 , along which the pouch S 1 is welded (thermally sealed), extends in the direction perpendicular to the lengthwise direction of the cushioning medium storage portion 3 . This process, which will be described later in detail, is done to prevent the problem that as the pouch S 1 is left unprotected in an environment which is high in temperature and humidity, and/or low in pressure, for a long period of time, the injected air in the cushioning medium storage portions 3 expands and leaks out of the pouch S 1 (cushioning medium storage portions 3 ). In other words, the pouch S 1 is thermally sealed across the area 48 to provide the cushioning medium storage portions 3 with regions, one for each cushioning medium storage portion 3 , in which the air having flowed backward through the check valve 4 can be held, up to a certain amount. In addition, in this embodiment, the pouch S 1 is thermally sealed along a line 51 , which is on the inlet 11 side of the line 50 . This process is done to prevent the air having escaped through the welding line 50 from leaking out of the inlet 11 . The welding line 51 also extends in the direction perpendicular to the lengthwise direction of the cushioning medium storage portion 3 . [0088] Further, referring to FIG. 8, as the cushioning medium is injected into the cushioning medium storage portions 3 of the pouch S 1 containing the cartridge 35 , the pouch S 1 changes in shape so that the four corners (C 1 , C 2 , C 3 , and C 4 ) thereof stick out relative to the edge between the corners C 1 and C 2 , and the edge between the C 3 and C 4 . These projecting corners C 1 , C 2 , C 3 , and C 4 add to the shock absorption performance of the pouch S 1 , better protecting the object therein when the pouch S 1 containing the object landed on one of its corners. [0089] In this embodiment, the cartridge 35 is inserted into the pouch formed of the above described inflatable wrapping material. S 1 comprising a desired number of inflatable cushioning units. However, the cartridge 35 may be airtightly sealed in the inflatable cushioning pouch S 1 by forming the inflatable wrapping material S 1 into a pouch by welding the half of the wrapping material S 1 , on one side of the cartridge 35 , to the other half of the wrapping material S 1 , on the other side, along the edges, after directly wrapping (covering) the cartridge 35 with the wrapping material S 1 . [0090] (6) Insertion of Wrapped Cartridge into Carton [0091] The airtightly sealed pouch S 1 , which is formed of the inflatable wrapping material S 1 , and which contains the cartridge 35 , is inserted into a carton 38 (FIGS. 24 and 25). Then, the tabs 38 a and 38 b of the carton are bent inward at 90°. Next, the tab 38 c of the carton 38 is bent inward onto the tabs 38 a and 38 b . Then, the tab 38 d of the carton 38 is bent inward onto the tab 38 c , and is glued to the tab 38 c . During this process, the appendages 38 c 1 and 38 c 2 of the tab 38 c are inserted into the slits 38 d 1 and 38 d 2 of the tab 38 d . Referring to FIGS. 24 and 34, a carton, such as the one in this embodiment, in which such an object as the cartridge 35 is placed, is structured so that the object can be inserted into the carton from one of the lengthwise ends. In comparison, a carton in accordance with the prior art is structured so that the object (cartridge 35 ) is to be inserted into the carton from the direction perpendicular to one of the lateral walls of the carton, as shown in FIGS. 27 and 36, for the following reason. That is, according to the prior art, the cartridge 35 is immovably placed in a packaging carton 43 through the following steps: the cartridge 35 is inserted into a packaging bag 42 ; a pair of side pads 39 and 40 are fitted to the lengthwise ends of the cartridge 35 , over the bag; and the combination of the cartridge 35 , bag 42 , and pair of side pads 39 and 40 is placed in the packaging carton 43 , as shown in FIGS. 39 and 40. [0092] The employment of the above described packaging carton in this embodiment structured so that an object (cartridge 35 ) to be packaged is to be inserted from one of the lengthwise ends of the packaging carton, along with the combination of the above described packaging pouch, and packaging method, offers the following benefits: [0093] (1) Instead of providing one of the lateral walls of a packaging carton, with an opening such as the opening 43 e of a packaging carton in accordance with the prior art, an opening 38 e is located at one of the lengthwise end of a packaging carton, making the packaging carton stronger in overall strength. [0094] (2) The packaging carton in this embodiment is smaller in the amount, that is, the size of surface area, of material necessary to make it than the packaging carton 43 in accordance with the prior art, as shown in FIGS. 25 and 27, for the following reason. That is, the tabs 38 a - 38 d in this embodiment are smaller than the tabs 43 b - 43 d . Therefore, the number of the full-sized development B 1 of the packaging carton 43 in accordance with the prior art, which can be fitted on a single sheet B 2 of cardboard, is only three, as shown in FIG. 31, whereas the number of the full-sized development B 3 of the packaging carton 38 in this embodiment, which can be fitted on the single sheet B 2 of cardboard is four, as shown in FIG. 32; in other words, only three packaging cartons 43 can be made from a single sheet B 2 of cardboard, whereas four packaging cartons 38 can be made from a single sheet B 2 of cardboard. Therefore, the employment of the structural design, in this embodiment, for a packaging carton, is effective to reduce packaging carton cost, and overall cartridge cost. [0095] (3) The number or the cartons 43 in accordance with the prior art which can be mounted on a transportation pallet B 4 is 180 (FIG. 33), whereas the number of the cartons 38 in this embodiment is 203 (FIG. 34), for the following two reasons. First, the carton 38 in this embodiment is smaller than the carton 43 in accordance with the prior art, and secondly, the carton 38 is greater in overall strength than the carton 43 in accordance with the prior art, as described in Paragraph (1). [0096] (4) The machine for making the packaging carton 38 can be made smaller than that for the packaging carton 43 , because the packaging carton 38 can be finished from a smaller cut of material (cardboard), or the like reason. [0097] (5) The packaging carton 38 is easier for a user to remove an object (cartridge 35 ) therefrom, because not only is the tearaway strip portion 38 f of the packaging carton 38 smaller than the tearaway strip portion 43 f of the packaging carton 43 , but also, the packaging carton 38 does not require the aforementioned pair or side pads. [0098] The wrapping method for wrapping an object with the above described wrapping material can be summarized as follows. [0099] The wrapping method for wrapping an object with the wrapping material S 1 comprising; a plurality of cushioning medium storage portions 3 for storing the cushiony medium; a plurality of the check valves 4 which allow the cushioning medium to pass through them into the cushioning medium storage portions 3 , one for one, but prevent the cushioning medium from flowing backward from the cushioning medium storage portions 3 through them; a plurality of the guiding portions 5 for guiding the cushioning medium into the cushioning medium storage portions 3 , one for one, through the check valves 4 from outside the wrapping material S 1 , in order to inflate the cushioning medium storage portions 3 ; the areas 48 , which is positioned upstream, in terms of the direction in which the cushioning medium is guided from the guiding portions 5 to the check valves 4 , of the check valves 4 , one for one, in order to prevent the portion of the cushioning medium having flowed backward from the cushioning medium storage portions 3 into the guiding portions 5 through the check valves 4 , from leaking out of the wrapping material S 1 , and across which the wrapping material S 1 is sealed after the cushioning medium storage portions 3 are filled with the cushioning medium, is characterized in that the wrapping material S 1 is sealed across the area 48 after an object is placed in the pouch formed of the wrapping material S 1 , and then, the cushioning medium is injected into the cushioning medium storage portions 3 through the guiding portions 5 . [0100] The wrapping method for wrapping an object with the wrapping material S 1 in accordance with the present invention is characterized in that each of the guiding portions 5 of the wrapping material S 1 used by the wrapping method has the inlet 11 , which is located at the outward end of the guiding portion 5 , and through which the cushioning medium is injected into the cushioning medium storage portion 3 from outside the wrapping material S 1 , through the check valves 4 , in the direction which is roughly the same as the direction in which the cushioning medium flows into the cushioning medium storage portion 3 through the check valve 4 . [0101] The wrapping method for wrapping an object with the wrapping material S 1 in accordance with the present invention is characterized in that plurality of cushioning medium storage portions 3 of the wrapping material S 1 used by the wrapping method are positioned parallel to each other; the plurality of check valves 4 of the wrapping material S 1 are provided one for each of the plurality of cushioning medium storage portions 3 , being independent from each is other; the plurality of the guiding portions 5 of the wrapping material S 1 are provided one for each of the plurality of cushioning medium storage portions 3 ; and the cushioning medium is injected into the cushioning medium storage portions 3 through the guiding portion 5 and check valves 4 , one for one. [0102] The wrapping method for wrapping an object with the wrapping material in accordance with the present invention is characterized in that each of the plurality of guiding portions 5 of the wrapping material S 1 used by the wrapping method is provided with the inlet 11 , which is positioned at the upstream end of the guiding portion 5 , in terms of the cushioning medium injection direction, to inject the cushioning medium into the cushioning medium storage portion 3 from outside the wrapping material S 1 ; the width W1 of the inlet 11 is less than the width W2 of the joint between the guiding portion 5 , and the check valve 4 located downstream of the guiding portion 5 in terms of the cushioning medium injection direction; and the plurality of inlets 11 are positioned side by side immediately next to each other. [0103] Incidentally, the above described wrapping method is a wrapping method suitable for manual operation. [0104] The wrapping method for wrapping an object with the wrapping material S 1 comprising: a plurality of cushioning medium storage portions 3 for storing the cushioning medium; a plurality of the check valves 4 which allow the cushioning medium to pass through them into the cushioning medium storage portions 3 , one for one, but prevent the cushioning medium from flowing backward from the cushioning medium storage portions 3 through them; a plurality of the guiding portions 5 for guiding the cushioning medium into the cushioning medium storage portions 3 through the check valves 4 , one for one, from outside the wrapping material S 1 , in order to inflate the cushioning medium storage portions 3 ; the area 48 which is positioned upstream, in terms of the direction in which the cushioning medium is guided from the guiding portions 5 to the check valves 4 , of the check valves 4 , one for one, in order to prevent the portion of the cushioning medium having flowed backward from the cushioning medium storage portions 3 into the guiding portions 5 through the check valves 4 , from leaking out of the wrapping material S 1 , and across which the wrapping material S 1 is sealed after the cushioning medium storage portions 3 are filled with the cushioning medium, is characterized in that it comprises: the preparatory step for preparing the wrapping material S 1 ; the positioning step for positioning an object in the pouch formed of the wrapping material S 1 ; the injecting step for injecting the cushioning medium into the cushioning medium storage portions 3 through the guiding portions 5 after the positioning step; and the sealing step for sealing the pouch across the area 48 . [0105] The wrapping method for wrapping an object with the wrapping material S 1 in accordance with the present invention is characterized in that in the preparatory step, the wrapping material S 1 is prepared, the guiding portions 5 of which have the plurality of inlets 11 , one for one, located at the upstream end, in terms of the injection direction, for injecting the cushioning medium from outside the wrapping material S 1 , and in the injection step, cushioning medium is injected through the inlets 11 in the direction roughly the same as the direction in which the cushioning medium passes through the check valves 4 toward the cushioning medium storage portions 3 . [0106] Further, the wrapping method for wrapping an object with the wrapping material in accordance with the present invention is characterized in that in the preparatory step, the wrapping material S 1 is prepared, which has the plurality of the cushioning medium storage portions 3 positioned in parallel immediately next to each other, the plurality of check valves 4 provided one for each cushioning medium storage portion 3 ; and the plurality of guiding portions 5 provided one for each cushioning medium storage portion 3 , and in the injection step, cushioning medium is injected into the cushioning medium storage portions 3 through the guiding portions 5 and check valves 4 . [0107] Further, the wrapping method for wrapping an object with the wrapping material, S 1 is characterized in that in the preparatory step, the wrapping material S 1 is prepared, which has the plurality of guiding portions 5 , each of which has the inlet 11 located at the upstream end, in terms of the cushioning medium injection direction, for injecting the cushioning medium from outside the wrapping material S 1 , the width W1 of the inlet 11 being less than the width W2 of the joint between the guiding portion 5 and the check valve 4 on the downstream side of the guiding portion 5 , in terms of the cushioning medium injection direction, and the plurality of inlets 11 being positioned immediately next to each other, and in the injection step, cushioning medium is injected through the plurality of inlets 11 . [0108] Incidentally, the above described wrapping method may be said to be suitable for a mechanical wrapping operation, for example, a wrapping operation using an automatic wrapping machine. [0109] (Cushioning Medium Guiding Portion 5 ) [0110] As described above, as the inflated wrapping material S 1 is left unprotected in an environment which is high in temperature and humidity, and/or low in pressure, the cushioning medium storage portion 3 increases in internal pressure, causing thereby the cushioning medium (air) in the cushioning medium storage portion 3 to flow backward through the check valve 4 . In this situation, the cushioning medium (air) in the cushioning medium storage portion 3 of the wrapping material in accordance with the prior art gradually leaks, because the wrapping material in accordance with the prior art is: not sealed across the guiding portion 5 , as shown in FIG. 12. Therefore, there is a concern that an object wrapped with the wrapping material in accordance with the prior art cannot be totally protected from shocks. [0111] Thus, in this embodiment, the guiding portion 5 is utilized as a buffer portion in which the air having flowed backward through the check valve 4 due to the increase in the internal pressure of the cushioning medium storage portion 3 is retained, as shown in FIGS. 10, 11, and 13 . In other words, the air having flowed backward from the cushioning medium storage portion 3 into the guiding portion 5 through the check valve 4 can be prevented, by sealing the wrapping material S 1 across the guiding portion 5 along the lines 50 and 51 , from leaking out of the wrapping material S 1 through the guiding portion 5 . With the wrapping material S 1 sealed across the guiding portion 5 , even if the cushioning medium (air) flows backward through the check valve 4 due to the changes in the environment in which an object wrapped with the wrapping material S 1 is stored, or due to the like cause, the cushioning medium does not leak out of the wrapping material S 1 . More specifically, when the inflated wrapping material in accordance with the prior art, that is, the wrapping material which did not have the buffer zone, was left unprotected in a severe test environment (40° in temperature and 95% in humidity), the internal pressure of this wrapping material S 1 , which was initially 50 Kpa, dropped to 0 Kpa in 24 hours. In comparison, when the inflated wrapping material S 1 in this embodiment was left unprotected in the same severe test environment (40° in temperature and 95% in humidity), the Internal pressure of this wrapping material S 1 , which also was 50 Kpa initially, was roughly 20 Kpa even after 60 days. Incidentally, at this rate of pressure loss, it will take 4.58 years for the internal pressure of 50 Kpa of the inflated wrapping material S 1 in this embodiment to drop to 10 Kpa, if the inflated wrapping material S 1 in this embodiment is left unprotected in the normal environment (23° in temperature and 60% in humidity). In other words, wrapping an object with the wrapping material S 1 in this embodiment assures that the object remains protected from shocks. [0112] One of the long edges of the wrapping material S 1 in this embodiment is provided with the notch 15 -, which corresponds in position to a point between the lines 8 and 50 (FIG. 6). The surface of the wrapping material S 1 is made coarse, across the adjacencies of the notch 15 , providing an anti-slip area, in order to make it easier for a user to Lear the wrapping material S 1 starting from the notch is. The anti-slip area is on the upstream side, in terms of the cushioning medium injection direction, from the line 8 (welding seam) along which the wrapping material S 1 is thermally sealed between the upstream end of the cushioning medium storage portion 3 and guiding portion 5 . The notch 15 is located outward of the line 12 , in terms of the direction perpendicular to the lengthwise direction of the cushioning medium storage portion 3 . Thus, as the wrapping malarial S 1 is torn starting from the notch 15 , the cushioning medium storage portions 3 are torn as shown in FIGS. 15 and 16, not only is an opening 21 through which the cartridge 35 can be taken out, but also, the air remaining in the cushioning medium storage portions 3 are released, reducing thereby the used wrapping material S 1 in volume, and therefore, making it easier to remove the cartridge 35 from the pouch formed of the wrapping material S 1 . Further, the wrapping material S 1 is welded along the lines 22 and 49 , as shown in FIG. 14( a ), in order to assure that the cushioning medium storage portions 3 (wrapping material S 1 ) are torn in the direction intersectional to the lengthwise direction of the cushioning medium storage portion 3 . FIG. 14( a ) is a plan view of the reverse side of the pouch, which is formed of the wrapping material S 1 and contains the cartridge 35 . The line 22 along which the wrapping material S 1 is welded is located 7 mm inward of the welding line 19 (check valve 4 ). These welding seams have a length of 20 mm and are positioned with predetermined intervals. The line 49 along which the wrapping material S 1 is welded is on the inward side of the line 22 . These welding seams also have a length of 20 mm and are positioned with predetermined intervals. The welding lines along the lines 19 and 49 are formed by thermal welding. Without the presence of the tear guiding welding seams 19 and 49 , the wrapping material S 1 (cushioning medium storage portions 3 ) are difficult to tear in the direction perpendicular to the lengthwise direction of the cushioning medium storage portion 3 , making it difficult to remove the object (cartridge 35 ) from the pouch formed of the wrapping material S 1 ; it is more likely for the wrapping material S 1 to be torn along the line 19 (welding seam), as shown in FIG. 14( c ), making it difficult to release the air in the cushioning medium storage portions 3 . Referring to FIG. 14( a ), the tear guiding welding seams 22 are extended astride the welding seams 10 between the adjacent two cushioning medium storage portions 3 , one for one, because, if the tear guiding welding seams 22 do not straddle the welding seams 10 one for one, the welding seams 10 resist the tearing action, making it virtually impossible to tear the wrapping material S 1 in the direction perpendicular to the guiding portion 5 , starting from the notch 15 . As will be evident from the above description, there are provided an interval 34 (portion which has not been welded) between the adjacent two welding seams 22 , and an interval 35 (portion which has not been welded) between the adjacent two welding seams 49 , so that even it the wrapping material S 1 were to become torn between the tear guiding welding seam 19 and tear guiding welding seam 22 , the cushioning medium (air) in the cushioning medium storage portions 3 can be released. These tear guiding welding seams 22 and 49 are created when the wrapping material S 1 is in the form shown in FIG. 3. [0113] The tear guiding welding seams 22 and 49 may be shaped like the tear guiding welding areas 38 shown in FIG. 23 a , tear guiding areas 39 in FIG. 23( b ), tear guiding areas 40 in FIG. 23( c ), or combinations of the tear guiding areas 41 and 48 in FIG. 23( d ). Also in these cases, there are provided the areas 43 , 44 , 46 , and 47 , respectively, across which the front and reverse sides of the wrapping material S 1 have not been welded to allow the air in the cushioning medium storage portions 3 to escape. [0114] (Cushioning Medium Storage Portion) [0115] The cushioning medium storage portion 3 in this embodiment is characterized in that it is provided with an area which is narrower, in terms of the direction perpendicular to the lengthwise direction of the cushioning medium storage portion 3 , than the rest of the cushioning medium storage portion 3 , and which is located at a predetermined location in terms of the lengthwise direction of the cushioning medium storage portion 3 . With the provision of this narrow area 3 b , the pressure which will apply to the cartridge 35 after the injection of the cushioning medium into the cushioning medium storage portions 3 can be reduced. Referring to FIG. 17, the width W4 of the narrow area 3 b is less than the width W3 of the upstream and downstream areas 3 a of the cushioning medium storage portion 3 , with respect to the narrow area 3 b , in terms of the air injection direction. In other words, the cross section of the narrow portion 3 b of the cushioning medium storage portion 3 is less than that of the other areas 3 a of the cushioning medium storage portion 3 . Also referring to FIG. 17, the narrow portion 3 b can bc formed by widening, in the direction perpendicular to the lengthwise direction of the cushioning medium storage portion 3 , the portion 23 of the welding seam 10 , across which the films 1 and 2 are welded to each other, within the range which corresponds in position to the narrow area 3 b . The wider welding seam 23 is also thermally formed by an dedicated welding apparatus (unshown). In this embodiment, the width W3 is in the range of 35-35 mm, and the width W4 or the narrow area 3 b is in the range of 15-20 mm. [0116] This embodiment is characterized in that the wrapping material S 1 is structured so that the amount by which air can be injected into the center portion of each of the cushioning medium storage portions of the wrapping material S 1 , which corresponds in position to the approximate center portion of an object (cartridge 35 ) to be wrapped, is smaller than the amount by which air can be injected into the upstream and downstream portions, in terms of the air injection direction, of each of the cushioning medium storage portions of the wrapping material S 1 , with respect to the center portion. Referring to FIGS. 7 and 8, in this embodiment, the amount of the air which can be injected into the center portion 3 b of the cushioning medium storage portion 3 is reduced by reducing the center portion 3 b in the width, in terms of the direction perpendicular to the lengthwise direction of the cushioning medium storage portion 3 , compared to the rest 3 a of the cushioning medium storage portion 3 . The width of the center portion 3 b of the cushioning medium storage portion 3 can be reduced by widening the welding seam 23 , across the range corresponding to the center portion 3 b . With the center portion 3 b of the cushioning medium storage portion 3 reduced in the amount of air injectable into it, the amount of the air pressure which applies to the approximate center portion of the object (cartridge 35 ) is smaller ( 19 ( a )). When the object to be wrapped with the wrapping material S 1 happens to be the cartridge 35 , the center portion of the cartridge 35 , where the housing 35 d , cover 35 b , handle 35 c , etc., of the cartridge 35 are located, is more likely to be deformed by the pressure from the air in the cushioning medium storage portion 3 than the end portions of the cartridge 3 . 5 . Further, the photosensitive drum 35 a and transfer roller 35 e of the cartridge 35 are likely to be deformed by the deformations of the housing 35 d , cover 35 b , etc., of the cartridge 35 , as shown in FIG. 19( b ). Thus. The portion 3 b of the cushioning medium storage portion 3 , which is narrower in terms of the direction perpendicular to the lengthwise direction of the cushioning medium storage portion 3 than the rest 3 a of the cushioning medium storage portion 3 is centrally positioned in terms of the lengthwise direction of the cushioning medium storage portion 3 , in order to prevent the pressure from the cushioning medium storage portion 3 from being applied to the center portion of the cartridge 35 . Thus, the wrapping material S 1 must be structured so that before the wrapping material S 1 is formed into a pouch, the narrow center portion 3 b of the cushioning medium storage portion 3 will align with the center portion of the object (cartridge 35 ) to be wrapped with the wrapping material S 1 . [0117] Referring to FIGS. 20 and 21, in the case of a wrapping material S 2 , the lengthwise direction of the cushioning medium storage portions 3 of which is perpendicular to the axial direction of the photosensitive drum 35 a of the cartridge 35 , it is possible to shut the check valves 28 by welding the front and reverse sides of the wrapping material S 2 to each other along a line 26 (welding seam), in order to prevent air from being injected into the area of the wrapping material S 2 , which corresponds in position to the center portion of the process cartridge 351 n terms of the axial direction of the photosensitive drum 35 a . With the provision of this structural arrangement. It is possible for the wrapping material S 2 to be inflated so that the center portion of the cartridge 35 is not pressured by the portion 25 of the wrapping material S 2 , as shown in FIG. 22( a ) (FIG. 22( b ) shows the cartridge 35 , the cartridge 35 d and cover 35 b of which have been deformed, as in FIG. 19( b )). FIG. 22( a ) shows that, as the cartridge 35 is wrapped with the wrapping material S 2 , the cushioning medium storage portions 25 of the wrapping material S 2 , into which air cannot be injected, is positioned against the handle 35 c of the cartridge 35 . [0118] As described above, in this embodiment, the width of each of the cushioning medium storage portions 3 of the wrapping material S 1 , in terms of the direction perpendicular to the lengthwise direction of the cushioning medium storage portion 3 , is reduced across its center portion, in terms of the lengthwise direction of the cushioning medium storage portion 3 , which corresponds in position to the center portion of the object (cartridge 35 ), in terms of the lengthwise direction of the cartridge 35 , or the cushioning medium storage portions 3 of the wrapping material S 2 , which correspond in position to the center portion of the cartridge 35 , are shut in order to prevent air from being injected into them. However, the structural arrangement in this embodiment may be modified as shown in FIG. 35, which shows the case in which an object (cartridge 35 ) having projections 44 and 47 , which are not centrally located, is wrapped with the wrapping material S. In this case, the cushioning medium storage portions 3 of the wrapping material S may be reduced in width, across the portions corresponding to the projections 44 and 47 of the object (cartridge 35 ), or the cushioning medium storage portions 3 of the wrapping material S may be shut across the portions corresponding to the projections 44 and 47 of the object (cartridge 35 ), in order to prevent the problem that the cushioning medium storage portions 3 are damaged by the projections 44 and 47 , and the air therein escapes from the cushioning medium storage portions 3 . [0119] Incidentally, the wrapping materials S (S 1 and S 2 ) in this embodiment were described with reference to the cartridge 35 as the object to be wrapped with the wrapping materials S (S 1 or S 2 ). However, the wrapping materials S may be used for wrapping the object other than the cartridge 35 ; for example, an ink cartridge for an ink jet printer, a camera, the main assembly of a printer, a video camera, a fixation unit removably mountable in an to electrophotographic image forming apparatus, etc. Further, the flexible material for the wrapping materials S may be paper film, metal film. etc. instead of plastic film. [0120] (Manufacturing Method for Wrapping Material) [0121] The manufacturing method for the inflatable wrapping material for wrapping an object can be summarized as follows. [0122] The manufacturing method, in accordance with the present invention, for inflatable wrapping material comprises: [0123] the sheet laying step for placing two pieces of flexible sheet, that is, the plastic films 1 and 2 , in layers; [0124] the cushioning medium storage portion forming step for welding the layered first and second films to each other, along multiple parallel lines (welding seams 9 and 10 ) in order to form the cushioning medium storage portions 3 for holding the cushioning medium; [0125] the cushioning medium storage portion sealing step for welding the plastic films 1 and 2 , having been layered in the sheet laying step, to each other along the line 6 (welding seam) in the adjacencies of one of the lengthwise ends of the wrapping material S formed in the cushioning medium storage portion forming step; [0126] the check valve attaching step for attaching the check valve which allows the cushioning medium to pass through it toward the cushioning medium storage portion while preventing the cushioning medium in the cushioning medium storage portion from flowing backward through it, to the lengthwise end of each of the cushioning medium storage portion, opposite to the thermally sealed end; and [0127] the guiding portion forming step for welding the plastic films 1 and 2 having been layered in the sheet layer step, the lines extending from the lines 9 and 10 (welding seams) to the lengthwise end of the wrapping material S, opposite to the sealed lengthwise end, in order to form the guiding portions 5 for guiding the cushioning medium into the cushioning medium storage portions, one for one, and also, in order to form, on the upstream of the check valve 4 in terms of the direction in which the cushioning medium is guided toward the check valve 4 through the guiding portion, the area 8 across which the wrapping material S will be sealed, after the injection of the cushioning medium into the cushioning medium storage portions, to seal the wrapping material S to prevent the portion of the cushioning medium having flowed backward from the cushioning medium storage portion 3 into the guiding portion 5 through the check valve 4 , from leaking out of the wrapping material S through the guiding portion 5 . [0128] The wrapping material S is shaped to be long and narrow, and comes in the form of a roll having a large number of wrapping materials S connected by their lengthwise edges so that the lengthwise edges of the wrapping materials S become perpendicular to the lengthwise edges of the roll, and the widthwise edges of the wrapping materials S become parallel to the lengthwise edges of the roll. [0129] The aforementioned manufacturing method for the wrapping material S 1 comprises the cutting step for obtaining a wrapping unit containing a desired number of wrapping materials S 1 by cutting the roll of wrapping materials S 1 in the direction perpendicular to the edges of the roll, that is, the direction parallel to the widthwise direction of the wrapping material S 1 . [0130] The manufacturing method also comprises: the folding step for folding the wrapping unit in the direction perpendicular to the widthwise direction of the wrapping material S 1 after the cutting step: and the pouch forming step for welding the two halves of the wrapping unit to each other along the long or short edges (welding seams 12 and 13 ), forming the wrapping unit into a pouch which is open across one of the edges. [0131] Further, the manufacturing method comprises: the object placement step for placing an object in the pouch formed in the pouch forming step; the cushioning medium injection step for injecting the cushioning medium into the cushioning medium storage portions through the guiding portions after the object placement step; and the sealing step for sealing the wrapping unit across the sealing area 48 after the cushioning medium injection step. [0132] Although, in the case of the wrapping material manufacturing method in this embodiment, the plastic films 1 and 2 placed in layers were attached to each other by welding, along the predetermined lines (welding seams). However, choice of the method for bonding the plastic film 1 and 2 does not need to be limited to welding; any means may be employed as long as the two films 1 and 2 can be sealed along the predetermined lines. [0133] According to this embodiment, it is assured that an object can be wrapped with the wrapping material S so that the cushioning medium in the wrapping material S will not leak out of the wrapping material S due to the changes in ambience, or the like. Further, it is possible to manufacture a wrapping material capable of protecting the wrapped object from shocks. Further, the wrapping material S can be injected with the cushioning medium after the shipment of the wrapping material S to its final destination, being therefore superior in transportation efficiency. Further, the wrapping material S can be modified in accordance with the properties of the object to be wrapped. [0134] As described above, according to the present invention, even if the cushioning medium in a wrapping material flows backward through the check valve due to the changes in ambience, or the like, it does not leak out of the wrapping material, assuring that an object will remain safely wrapped, that is, remains protected from external shocks. Also according to the present invention, the lengthwise direction of the wrapping material, and the direction in which the cushioning medium is injected through the inlet, are made roughly the same as the direction in which cushioning medium passes through the check valve. Therefore, the wrapping material in accordance with the present invention is superior in the efficiency with which the cushioning medium can be injected into the cushioning medium storage portions of the wrapping material. Further, according to the present invention, a wrapping material may be injected with cushioning medium after the shipment of the wrapping material to its final destination, being therefore superior in transportation efficiency. [0135] While the invention has been described with reference to the structures disclosed herein, it is not confined to the details set forth, and this application is intended to cover such modifications or changes as may come within the purposes of the improvements or the scope of the following claims.

A packing member for packing an article, includes a medium accommodating portion for accommodating medium; a non-return valve for passing the medium to the medium accommodating portion and stopping the medium away from the medium accommodating portion; an introducing portion for introducing the medium into the medium accommodating portion with the non-return valve from an outside of the packing member to balloon the medium accommodating portion; and a sealing region, disposed upstream of the non-return valve with respect to a direction of the introduction of the medium from the introducing portion toward the non-return valve, for sealing against the introduction of the medium to prevent leakage from the introducing portion to an outside of the packing member, the sealing region being sealed to keep the medium in the medium accommodating portion.

RELATED APPLICATIONS [0001] The present application is a divisional application of a U.S. application Ser. No. 09/719,728 filed Dec. 13, 2000, which is a US national phase application corresponding to PCT/IL98/00285 filed Jun. 16, 1998. FIELD OF THE INVENTION [0002] The invention relates to the illumination of substantially flat surfaces in order to perform visual inspection of the surfaces and in particular to the illumination of printed circuit boards in order to perform visual inspection thereof by machine. BACKGROUND OF THE INVENTION [0003] Modern printed circuit boards are typically laminated from numerous layers, the planar surface of each layer comprising an intricate pattern of conducting regions, formed for example from 1-2 mil thick copper, separated by regions of non-conducting substrate. A fault in any intermediate layer of the board may result in malfunction of the entire board. Consequently, it has become standard practice to check for the existence, integrity and shape of features existing on each of the printed circuit board layers during manufacturing and prior to lamination. [0004] The inspection of complicated printed circuit board layers is generally done optically by machine. The printed circuit board is placed on the machine to enable partial viewing of the board by the collecting optics of an imaging system, and is subsequently scanned. While passing through the field of view of the collecting optics, it is illuminated by an appropriate illumination system. [0005] In prior art systems a single CCD array and illuminator is typically employed. Such conventional arrays and illuminators are typically insufficiently long to acquire an image of the entire width of the printed circuit board in a single pass. As a result, in addition to moving the board and collecting optics relative to each other in a principal scanning direction, the machine must additionally move the board and collecting optics in a second, orthogonal, direction in order to construct an image of the entire board. The result is a composite, image comprised of long thin contiguous strips, on the order of 0.5 mil wide, acquired sequentially from subsequent passes of the CCD array over different sections of the printed circuit board surface. Each strip approximates the field of view of the CCD array. [0006] The acquired image is next analyzed and a map of features on the board is prepared. This resulting map can then be compared, by computer, to a stored map of predetermined features or design rules to which the board is supposed to conform. [0007] Different regions on a printed circuit board may be distinguished by their reflective behavior when exposed to a source of light. For example, the conducting material on a printed circuit board is generally a more specular, if somewhat diffusing reflector of white light relative to the substrate material which is generally more diffuse. Moreover, by relying on differences in spectral reflection properties, it is possible to enhance the contrast between laminate and conductor by using appropriate color filters. [0008] Because image processing of a an image acquired from a printed circuit board relies on an analysis of the reflective properties of its various features, the process can be highly sensitive to the qualities of the light used to illuminate the board. For example, boards are made up of various materials each having differing reflective properties. Additionally, the surface of boards have a topographical relief that may be resultant both from the cross sectional shape of the conductors, as well as surface microstructure. As a result, the intensity or brightness of a reflection of an inspected feature on a board may be dependent not only on the inherent reflective properties of its materials, but also on its surface topography. [0009] To provide an effective illumination in automated optical inspection applications it is necessary to mitigate the effects of topographical variations on a board's surface. Thus, it is known to highly concentrate light along a relatively thin line by using a source configured to emanate light over a relatively wide solid angle of illumination [0010] It is believed that the following patents represent the state of the art in high intensity concentrated illumination for automated inspection of printed circuit boards: U.S. Pat. No. 4,421,410 to Karasaki et al, U.S. Pat. No. 4,877,326 to Chadwick et al, U.S. Pat. No. 4,801,810 to Koso, U.S. Pat. No. 5,058,982 to Katzir et al, and U.S. Pat. No. 5,153,668 to Katzir et al., the disclosures of all of which are incorporated herein by reference. [0011] In some conventional illuminators that provide a wide solid angle concentrated illumination, the strip of the board being inspected is illuminated with light from three linear illumination sources that are fixed substantially parallel to the strip. Light from a first of the illumination sources is concentrated onto the strip from a direction substantially perpendicular to the surface of the board by a cylindrical lens or a section of an elliptical cylindrical mirror running the length of the first light source. Light from a second illumination source is concentrated by a similar lens or mirror onto the strip from a first oblique angle with respect to the normal to the surface. Light from a third illumination source is concentrated similarly onto the strip from a second oblique angle to the normal that is equal and opposite to the first oblique angle. In some of the prior art illuminators, the three illumination sources are configured to create a contiguous solid angle of concentrated light. [0012] For the purposes of clarifying terminology as used herein, it is noted that on-axis illumination is defined as illumination that a reflecting surface parallel to the plane of the workpiece would specularly reflect in a direction along the axis of the collecting optics. Off-axis illumination is defined as illumination that is reflected into the collecting optics by surfaces that are not parallel to the plane of the printed circuit board. In the conventional illuminators, the on-axis illumination illuminates the board from a direction substantially normal to the area of the board being illuminated, while the off-axis illuminators each respectively illuminate the board from directions on either side of the on-axis illumination. [0013] The prior art concentrating broad solid angle illuminators comprise many optical components that must be accurately positioned in order to provide a wide solid contiguous angle of illumination. Settings of the various light sources must also be accurately adjusted. Furthermore these settings and positions must be stabilized and accurately maintained in an environment subject to vibration and large heat transfers. Additionally the “seams” or boundaries between the on-axis illumination and the two off-axis illumination regions are generally defined by the edges of the mirrors or lenses used to concentrate on-axis and off-axis illumination on a board. These seams or boundaries are therefore sharp and generally obtrusive. This makes it difficult to assure that on-axis illumination and off-axis illumination are smoothly blended to provide a substantially uniform illumination throughout the broad angle of illumination over the area of an illuminated strip. [0014] As a result of these difficulties, mechanical and optical components of prior art concentrated illuminators require very tight tolerances and are relatively expensive. Furthermore these difficulties have restricted the lengths of the effective region of illumination to the order of 15 cm, which length is often less than the width of the board being inspected. [0015] An illuminator for providing concentrated light, but having an altogether different design is shown in U.S. Pat. No. 4,801,810. In this patent an elliptical reflector comprising approximately one-half of an elliptical cylinder is used to illuminate the surface of a printed circuit board. The axis of the ellipse is placed at an oblique angle to the surface of the board, with the surface being placed at one focus of the ellipse and a single source of illumination being placed at the second focus. An imaging system images the illuminated line on the board from an angle equal (but opposite) to the angle at which it is directly illuminated by the source. This system provides uneven off-axis illumination of the line on the board and does not allow for independent adjustment of on-axis and off-axis illumination since only a single source is used for illuminating the board from all directions. SUMMARY OF THE INVENTION [0016] The present invention is generally described in the context of illumination and inspection of printed circuit boards or their constituent layers which comprise a metal pattern on a non-conducting substrate. However, as will become evident, the present invention is applicable to the automated inspection of many other types of patterned surfaces such as artwork, negative or positive masters (photomasks), hybrid circuits (with suitable scaling) and the like. To emphasize this broader applicability of the invention, the term “workpiece” is used herein to refer to these broader applications and the term “printed circuit board” is used when referring to printed circuit boards, proper or their constituent layers. [0017] One aspect of some preferred embodiments of the invention provides on-axis and off-axis illumination of workpieces from the same apparently contiguous source, wherein the illumination intensity of the on-axis and off-axis illumination is separately adjustable. [0018] Differently stated, this aspect of the invention provides for a seamless wide angle source of concentrated on-axis and off-axis illumination, wherein the intensity of the illumination for each of the on-axis and off-axis illumination is separately adjustable. [0019] Prior art systems provide for either such adjustability or for a seamless illumination. As indicated above, such seamless illumination is desirable to avoid artifacts in images of printed circuit boards. Separate variation of on-axis and off-axis illumination is desirable to allow for adjustment of the two separate illuminations to achieve a uniform level of lighting, or to account for various reflectivities and roughness of the objects being imaged. For example, when viewing photomasks, in which black lines are formed on a clear substrate and the substrate is imaged against a matte surface, optimal contrast is achieved when the on-axis illumination is zero to avoid specular reflection from the “black” lines which reflect weakly, but specularly. Additionally, the signal to noise ratio of images of printed circuit boards may be optimized by reducing the intensity of off-axis illumination relative to the on-axis illumination. This is the result of an increase in reflection from the non-conducting portions of the boards and a decrease in mottling as off-axis illumination is increased. [0020] An aspect of some preferred embodiments of the present invention provides for the center of the on-axis illumination to be at an oblique angle to the surface of the workpiece. In addition, the angular extent of the off-axis illumination is preferably substantially equal on both sides of the on-axis illumination. [0021] Another aspect of some preferred embodiments of the present invention also provides for the center of the on-axis illumination to be at an oblique angle to the surface of the workpiece. In addition, this aspect provides for the on-axis and off-axis illumination to be separately adjustable. [0022] As known to the inventors, prior art systems which provide for the center of the on-axis illumination to be at an oblique angle to the surface of printed circuit boards provide for neither separate adjustability nor equal angular extent of the off-axis illumination on either side of the on-axis illumination. [0023] Equal angular extent of off-axis illumination results in less mottle, while oblique illumination allows for a seamless transition between the on-axis and the off-axis illumination. However, the combination of these qualities in a single illumination system has not been available in the prior art. [0024] Furthermore, prior art systems with non-normal on-axis illumination provided illumination from substantially all directions above the surface being illuminated (except for the direction of the imaging system). The present inventors have determined that it is desirable to limit the extent of off-axis illumination, at least when viewing printed circuit boards, since, while the mottle is decreased with increasing angle of illumination, the signal from the non-metallic portions of the workpiece increases faster than that from the metallic portion, resulting in a reduction in signal to noise ratio. [0025] One aspect of some preferred embodiments of the present invention provides an illuminator for providing a wide solid angle of continuous concentrated illumination, comprising fewer optical elements than many prior art broad angle concentrating illuminators and/or less complicated construction of the parts. [0026] Another aspect of some preferred embodiments of the present invention provides for a smooth seamless off-axis illumination and seamless blending of on-axis and off-axis illumination in an illuminator providing wide solid angle of continuous illumination, even when the intensities of the on-axis and off-axis sources are different. [0027] Another aspect of some preferred embodiments of the present invention provides an illuminator that can provide wide solid angle of concentrated illumination for strips on the surface of a workpiece that are longer than strips that are illuminated by prior wide solid angle concentrating illuminators. This is made possible, in some measure, by the simplification in construction of the parts used in the system and in their alignment. [0028] According to another aspect of some preferred embodiments of the present invention, a method is provided for determining the position and size of an optimum virtual illumination source to be used as a source of illumination when the actual source of illumination is used with a diffuser. [0029] According to still another aspect of some preferred embodiments of the present invention an automated optical inspection system is provided, wherein inspected workpieces are illuminated using an illuminator configured according to the teachings herein. [0030] According to still another aspect of some preferred embodiments of the present invention, a method for inspecting workpieces is provided, such method incorporating the steps of illuminating the workpiece with illumination provided by an illuminator according to the teachings herein. [0031] According to an additional aspect of some preferred embodiments, a suitable reflector for use in the illuminator according to the teachings herein, and method for manufacture thereof, is provided. [0032] An illuminator in accordance with a preferred embodiment of the present invention comprises a single linear light source hereafter referred to as an “on-axis source” to provide on-axis illumination. A different single linear light source, hereafter referred to as an “off-axis source”, provides off-axis illumination. [0033] In a preferred embodiment of the invention, a first, off-axis, illumination source is placed substantially at one focus of a reflector which forms a minor part of a cylindrical elliptical surface. The workpiece is placed at the other focus of the reflector. The workpiece is oriented at an angle to the off-axis illumination such that, if the workpiece were a specular reflector, light reflected from it would be oriented such that it would not be reflected back toward the mirror. Thus, the surface of the workpiece is not perpendicular to the center of the off-axis illumination. [0034] In a preferred embodiment of the invention, a narrow rectangular planar strip mirror is placed between the off-axis source and the reflector, such that the off-axis illumination reaching the workpiece is split into two non-joining parts, each part having a substantially equal angle of illumination and separated by an angular wedge shaped gap. Image collecting optics is placed such that its axis just intercepts the extreme edge of the off-axis illumination. [0035] In a preferred embodiment of the invention, the on-axis source is placed substantially at a virtual focus of the ellipse as reflected by the planar strip mirror. Light from this source will be reflected from the mirror and will illuminate the workpiece with on-axis illumination with respect to the collecting optics. The two sources will provide a seamless illumination of the workpiece since light from the off-axis source will illuminate from angles which are not “covered” by the strip and the on-axis source will illuminate only from central angles thus filling the gap between the parts of the off-axis illumination. This system is seamless, self aligning and provides for off-axis and on-axis illumination, seemingly from a single source but which has separate adjustability for the off-axis and on-axis illumination respectively. [0036] In a preferred embodiment of the invention, a diffuser is placed in front of each of the off-axis and on-axis sources such that each of these sources provides a different, broader effective source of illumination. One aspect of some embodiments of the invention provides a method of determining the effective width and effective position of the resulting sources of illumination. [0037] Yet another aspect of some preferred embodiments of the invention provides for multi-spectral detection of light reflected from the workpiece. In a preferred embodiment of the invention, R, G & B are separately detected and a composite “gray level” reflection value is generated by weighting the measured intensities of the three detected colors. Preferably the weighting is determined to give an optimum contrast between the metal and substrate for printed circuit boards (or for other workpieces in which the elements being differentiated have different colors) and is a function of color of the two materials, of the color of the illumination and possibly of the extent of the illumination. It should be understood that other methods of weighting such as filtering of the reflected light may be utilized. However, such methods are less precise and generally less efficient than weighting the signals. In a preferred embodiment of the invention, the light is preconditioned, as by filtering, to provide substantially independent detection of different spectral segments by the detectors. [0038] There is thus provided, in accordance with a preferred embodiment of the invention, illuminator apparatus for illuminating a workpiece during visual testing thereof, the illuminator comprising: [0039] a source of illumination that illuminates a portion of the workpiece with on axis illumination having a first intensity and off-axis illumination having a second intensity; and [0040] an optical viewing system, that views said portion of the workpiece and accepts light reflected from the workpiece over a range of angular directions, said range of angular directions defining said on-axis illumination, [0041] wherein said on-axis and off-axis illumination have separately adjustable intensities and appear to emanate from a contiguous source. [0042] There is further provided, in accordance with a preferred embodiment of the invention, illuminator apparatus for illuminating a workpiece during visual testing thereof, the illuminator comprising: [0043] a source of illumination that illuminates a portion of the workpiece with on-axis illumination centered at a first angular direction and having a first intensity and with off-axis illumination having a second intensity; and [0044] an optical viewing system, that views said portion of the workpiece and accepts light reflected from the workpiece over a range of angular directions, centered at a second angular direction, said range of angular directions defining said on-axis illumination, [0045] wherein said first intensity and second intensity are separately adjustable and wherein the first angular direction is different from the second angular direction. [0046] Preferably, the off-axis and on-axis illumination together illuminate the workpiece over a second range of angles, said second range of angles being substantially centered at said first angular direction. [0047] Preferably, the illumination illuminates the workpiece from angles ranging over substantially less than a total range of 180°, more preferably less than 100°. [0048] In accordance with a preferred embodiment of the invention, the source of illumination includes a first source of illumination that produces the on-axis illumination and a second source of illumination that produces the off-axis illumination. Preferably, the illumination produced by the first source and the second source illuminate the workpiece without any gap between the on-axis and off-axis illumination. Preferably, the apparatus includes a mirror from which the first source is reflected to illuminate the workpiece. Preferably, the mirror has an extent and the second source is situated behind the mirror such that the mirror blocks illumination therefrom from illuminating the workpiece and wherein said off-axis illumination is comprised of illumination from the second source which passes the mirror outside its extent. Preferably, the mirror is mounted on a transparent substrate having an extent greater than the extent of the mirror. [0049] In a preferred embodiment of the invention, the first source and the second source are substantially optically equidistant from the mirror. [0050] A preferred embodiment of the invention includes a concentrating mirror that receives illumination from the first and second sources and concentrates the illumination onto the workpiece. Preferably, the concentrating mirror comprises an elliptical mirror portion. Preferably, the first and second sources are optically situated substantially at a focus of the elliptical mirror. [0051] In a preferred embodiment of the invention, the concentrating mirror comprises a base having the general shape of the mirror and a metal foil adhered to the base. Preferably, the metal foil is adhered to the base by a vacuum applied to the metal foil. [0052] In a preferred embodiment of the invention, the workpiece is situated substantially at a second focus of the elliptical mirror. [0053] In a preferred embodiment of the invention the first source and the second source are line sources. Preferably, the line source comprises a radiant line source and a diffuser through which light that illuminates the workpiece from said line source passes. [0054] There is further provided, in accordance with a preferred embodiment of the invention, apparatus for visual inspection of a workpiece comprising: [0055] illumination apparatus according to any of the preceding claims; and [0056] an optical sensor that receives light from the optical viewing system and produces image signals in response thereto. [0057] Preferably, the apparatus includes: [0058] means for moving the workpiece relative to the illumination apparatus such that the optical sensor produces image signals representative of successive portions of the workpiece. [0059] Preferably, the on-axis illumination illuminates the workpiece from a range of directions having an angular extent of between about 4° and about 8°, more preferably about 6°. [0060] In a preferred embodiment of the invention, the on-axis and off-axis illumination illuminate the workpiece from a range of directions having an angular extent of between 30° and about 60°, more preferably between about 39° and 45°. [0061] In preferred embodiments of the invention, the workpiece comprises a printed circuit board. [0062] there is further provided, in accordance with a preferred embodiment of the invention, a mirror comprising: [0063] a base having the general shape of the mirror; and [0064] a metal foil forming a mirror surface adhered to the base by a vacuum. [0065] Preferably, the metal foil has a thickness between about 0.25 mm and about 0.45 mm, more preferably between about 0.25 mm and about 0.35 mm and most preferably about 0.35 mm. There is further provided, in accordance with a preferred embodiment of the invention, an illuminating system for illuminating a workpiece during visual inspection thereof, comprising: [0066] a linear source of radiation, comprising: a line source; a diffuser; situated on one side of the line source; and [0069] a reflector having at least one focus situated on the other side of the diffuser from the line source, wherein an effective position of the linear source of radiation situated between the line source and the diffuser is situated at the focus of the reflector. [0070] There is further provided, in accordance with a preferred embodiment of the invention, an illuminating system for illuminating a workpiece during visual inspection thereof, comprising: [0071] a light source emitting light over a continuous angle of illumination toward the workpiece; [0072] a blocking element that block light over a portion of the continuous angle such that two portions of the illumination, separated by a blocked angle illuminate the workpiece from the source. [0073] Preferably the apparatus comprises a concentrator that receives the unblocked portions of light and concentrates the illumination onto the workpiece. Preferably, the source of light is placed at a focus of the concentrator. Preferably, light from the source of light is concentrated at a focus of the concentrator. Preferably, the concentrator is a mirror. [0074] In a preferred embodiment of the invention the concentrator is an elliptical mirror and wherein the source of light is situated at one focus of the elliptical mirror and the light emitted by the source is concentrated at a second focus of the elliptical mirror. [0075] Preferably, the position of the blocking element is adjustable, such that the angular extent of the two sections of illumination is adjustable. [0076] Preferably, the blocking element supplies illumination to the workpiece over the blocked portion of the continuous angle. [0077] In a preferred embodiment of the invention, the blocking element comprises a planar strip mirror having a mirrored surface facing away from the light source. Preferably, the apparatus includes an additional source of illumination that supplies illumination to the mirror from which it is reflected in generally the same direction as the illumination from the light source. Preferably, the light source are at the same effective position when viewed from the mirror side of the strip mirror. [0078] In a preferred embodiment of the invention one or more of the intensity, polarization and wavelength of at least one of the light source and the additional source are separately adjustable. [0079] There is further provided, in accordance with a preferred embodiment of the invention, an automated optical inspection system for inspecting substantially flat workpieces, comprising: [0080] illuminating apparatus as described above; [0081] an imager that images a workpiece illuminated by the illuminator; and [0082] an image analyzer that analyzes the image and determines the existence of defects in the workpiece. [0083] The invention will be more clearly understood by reference to the following description of preferred embodiments thereof read in conjunction with the accompanying figures. Identical structures, elements or parts that appear in more than one of the figures are labeled with the same numeral in all the figures in which they appear. Analogous structures, elements or parts that appear in more that one of the figures are labeled with an analogous series of numerals in the figures in which they appear. BRIEF DESCRIPTION OF FIGURES [0084] FIG. 1 shows a simplified cross sectional view of an illuminator, in accordance with a preferred embodiment of the invention; [0085] FIG. 2 is a schematic cross-sectional view of an illuminator, in accordance with a preferred embodiment of the invention; [0086] FIG. 3 is a schematic cross section of a diffused source, in accordance with a preferred embodiment of the invention; [0087] FIG. 4 illustrates ray tracing of light rays used to determine a virtual light source corresponding to the source of FIG. 3 , in accordance with a preferred embodiment of the invention; [0088] FIG. 5 schematically illustrates a method of illuminating and constructing a long linear source of illumination, in accordance with a preferred embodiment of the invention; and [0089] FIG. 6 is a block diagram illustration of a printed circuit board inspection machine including the illumination system of this invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS [0090] FIG. 1 shows a perspective view of a simplified schematic of an illuminator 10 , in accordance with a preferred embodiment of the present invention. Illuminator 10 comprises a cylindrical reflector or mirror 12 having a substantially elliptical shape and a limited extent with an off-axis substantially uniform linear source of illumination 14 placed at one focus thereof and a workpiece or other substrate 16 , to be optically examined placed at another focus thereof. A front surface strip mirror 18 is placed between off-axis source 14 and mirror 12 , with the mirrored surface facing away from off-axis source 14 . The width of strip mirror 18 is such that it allows light from off-axis source 14 to be concentrated by mirror 12 and to reach substrate 16 from two angular sectors each having a width β each as shown, separated by a wedge shaped region of angular extent γ. It should be noted that while strip mirror 18 is shown as being mounted on a substrate 20 which has the same width as strip mirror 18 , substrate 20 may be wider than the strip mirror it supports (as shown in FIG. 2 ). It is readily appreciated that the position and arrangement of mirror 12 may be adjusted to adjust the relative angular extents of each of sectors β. [0091] A narrow substrate 20 , as shown, may be formed completely of metal. Such a structure introduces fewer aberrations into the off-axis illumination than when a wide glass support is used. The choice between the two structures is based, at least in part by the length of the strip mirror and the stability requirements of the system. In a preferred embodiment of the invention, the dimension (β+γ/2) may vary from about 15° to 30°, and most preferably is about 19.5° to 22.5°. In a preferred embodiment of the invention γ may vary from about 4° to 8° and most preferably is about 6°. [0092] A second, on-axis linear illumination source 22 , similar to off-axis source 14 , is placed, in accordance with a preferred embodiment of the invention, substantially at the reflection of the focus of the elliptical reflector as reflected by strip mirror 18 . Thus, illumination from on-axis source 22 , reflected by strip mirror 18 illuminates the other focus of the elliptical reflector within the same angular extent as that which mirror 18 blocks the illumination from source 14 , namely the angle γ. [0093] To more clearly understand how a preferred embodiment of the illumination system of FIG. 1 provides substantially seamless illumination, assume that only the off-axis source 14 is on. Light rays from the off-axis source 14 that are incident on the back surface of strip mirror 18 are “shadowed out” from the front side of the strip mirror. Strip mirror blocks these rays and they are thus are not concentrated by mirror 18 onto workpiece 16 . Light rays from off-axis source 14 that are not incident on the strip mirror pass to the right and left sides of the strip mirror 18 . [0094] Assume the on-axis source 22 is turned on. Light rays from the on-axis source 22 , which is adjacent to the front side of strip mirror 18 , are incident on the front surface of strip mirror 22 , and are reflected therefrom to reflector 12 . Light rays from on-axis source 22 that are not incident on the strip mirror pass to the back side of the strip mirror. [0095] Because the on-axis source is at substantially the same point optically as the off-axis source, light rays from the on-axis illumination source that are reflected back to the front side of the strip mirror appear to come from the same point as does the off-axis illumination source. If the angular radiance of the two sources is the same, these reflected light rays from the on-axis source replace those light rays from the off-axis source in the gap shadowed out by the strip mirror. The strip mirror “seamlessly” combines light from the off-axis illumination source and the on-axis illumination source so that all the light on the front side of the strip mirror appears to be radiated by a single illumination source. The alignment of such a system is thus seen to be not only simple and straightforward but also much less critical than that of most prior art systems. Furthermore, the optical components may be less precise than in prior art systems. Finally, the number of components is generally reduced and the components are more simply (and inexpensively) formed and assembled. [0096] In a preferred embodiment of the invention, sources 14 and 22 are provided by illuminating a fiber bundle and then spreading the fibers into a line source. This provides a uniform linear illumination source. [0097] While the angular extent of the left and right off-axis illumination is adjustable by positioning of strip mirror 18 , it has been found to preferably be substantially the same. It may be noted that when the angular extent of each of the left and right off-axis illuminations is the same, the portion of mirror 12 which is illuminated by each of the left and right off-axis illuminations is not the same. [0098] It may also be noted that the illumination intensity of the on-axis and off-axis sources respectively may be individually adjusted. This allows for attaining an even illumination across the entire angle of illumination (2β+γ), or for making either the intensity of either the on-axis illumination or the off-axis illumination stronger relative to the other. Alternatively or additionally the polarization or wavelength of the off-axis and/or the on-axis sources may be varied. [0099] In a preferred embodiment of the invention mirror 12 is formed of an aluminum foil having a nominal thickness of preferably between about 0.25 mm and 0.35 mm, most preferably about 0.35 mm±about 5 micron. These values are chosen to give reasonable precision and stability to the mirror. In a preferred embodiment of the invention, mirror 12 is mounted on a machined part 13 to which it is attached by vacuum (with a reflective surface facing away from the machined part) such that the required optical surface finish is provided by the aluminum foil and the shape is provided by the machined part. [0100] Collecting optics 24 is provided to image the illuminated line on the workpiece onto a plurality of detectors, (such as CCD elements) preferably formed into one or more line detectors 25 , 26 and 27 (shown as points on FIG. 1 since they are viewed end on). The axis of collector optics 24 is oriented at an angle with respect to the workpiece such that it would intercept the central ray of the on-axis illumination that would be reflected from the workpiece, were the workpiece to be a specular reflector. The aperture of the collector optics is such that it would be overfilled by the on-axis radiation from such a specular surface. In a preferred embodiment of the invention, as will be described in greater detail below, a series of axially spaced lenses or lens systems forming an optical array 28 ( FIG. 6 ) is provided, each of which lens systems images one of a plurality of preferably overlapping portions of the illuminated portion of the workpiece onto CCD lines 25 - 27 . [0101] Each of the CCD line detectors may comprise a single axial line of such detector elements or a strip a few elements wide. Such a strip preferably images a strip segment of the workpiece which is about 0.5 mm wide. This width and the spacing of the CCD elements in a line detector may vary depending on the desired measurement resolution of the system. It should be understood that the effective optical length and spacing of the CCD elements in the direction of motion of the workpiece depends on the sampling rate of the signal from the detectors and the velocity of the workpiece as it passed through the illuminator [0102] In a preferred embodiment of the invention, multi-spectral detection of light reflected from the workpiece is performed, and each of lines 25 - 27 is sensitive to a different, preferably substantially non-overlapping, portion of the spectrum. In a preferred embodiment of the invention, R G & B are separately detected and a composite “gray level” reflection value is generated by weighting the measured intensities of the three detected colors. Preferably the weighting is determined to give an optimum contrast between the metal and bare substrate, and is a function of color of the two materials, of the color of the illumination and possibly of the extent of the illumination. It should be understood that other methods of weighting such as filtering of the reflected light by filters (not shown) may be utilized. However, such methods are less precise and generally less efficient than weighting the signals. In a preferred embodiment of the invention, the light is preconditioned, as by filtering, to provide substantially independent detection of different spectral segments by the detectors. This may be desirable when the detector elements are sensitive to overlapping spectral segments. [0103] In preferred embodiments of the invention, one or more improvements and/or variants on the basic system as described with respect to FIG. 1 may be employed. These improvements are described together with respect to FIGS. 2 and 3 . However, it should be understood that preferred embodiments of the invention may have one or more, or none of the embellishments of FIGS. 2 and 3 . [0104] In accordance with a preferred embodiment of the invention, each of linear sources 14 and 22 ( FIG. 1 ) comprises, now as shown in illuminator 110 ( FIG. 2 ) a wide strip of source illumination, 114 and 122 . For simplicity of the drawing, only on-axis source 122 in FIG. 2 is shown as an extended source. As is evident from FIG. 2 , on-axis-source 122 illuminates a region of a workpiece 116 having a given width rather than the line illumination shown in FIG. 1 . [0105] In general, the illumination system shown has aberrations. Since the acceptance angle of the off-axis illumination is larger than that of the on-axis illumination and since it depends on a larger portion of mirror 112 for its focusing effect, it can be expected to be more subject to variations in intensity near the edges of the field. Therefore, in a preferred embodiment of the invention, source 114 is wider than source 122 . Preferably, only that portion of the workpiece for which uniform illumination by source 122 is provided, is used in the analysis of the workpiece. [0106] FIG. 2 also shows the effect of a finite thickness and extent of substrate 120 on which strip mirror 118 is mounted. The net effect of the substrate 120 is to cause a slight deflection in the position of source 114 as well as a difference in aberrations for the on-axis and off-axis illumination. This causes a small but usually unobjectionable, and sometimes desirable, smoothing of the joining of the off-axis and on-axis illumination. Preferably source 114 will be slightly broadened to prevent loss of illuminance uniformity due to the aberrations. [0107] The uniformity of illumination is controlled by the relative radiance of on-axis illumination and off-axis illumination as observed at each point in the strip region being illuminated 123 . When the radiance (light flux per unit area and unit solid angle) of light radiated by the on-axis illumination source is controlled to be substantially equal to the radiance of light radiated by the off-axis illumination source, each point in the illuminated strip region 123 is illuminated by substantially equal illumination intensity for incident angles of light rays between angles ±(β+γ/2). Under these conditions, in the range of incident angles between ±(β+γ/2), an illuminator in accordance with a preferred embodiment of the present invention provides substantially uniform illumination. For PCB inspection, the total half angle ±(β+γ/2) is preferably limited to less than 30°, and more preferably to about 22.5°, so as to obtain an optimum contrast and signal to noise ratio. [0108] In an illuminator in accordance with a preferred embodiment of the present invention, strip mirror 118 is a narrow reflecting lamination or deposit on a planar surface of a relatively rectangular substrate 120 , such as a plate of glass. Strip mirror 118 and off-axis light source 114 are preferably positioned with respect to the substrate 120 , and the substrate 120 is preferably sufficiently wide, so that all the light from the off-axis illumination source that is concentrated onto a strip of a workpiece passes through the glass of substrate 120 . [0109] The structure of a preferred illumination source for use with a preferred embodiment of the present invention shown in FIG. 2 , is now shown in FIG. 3 . Linear light sources 114 and 122 used for on-axis and off-axis illumination preferably comprise ends of optical fibers 136 that are fanned out from at least one fiber bundle 138 so that the ends are coplanar and lie in a dense linear array having a shape of a long narrow rectangle. The bundle of end or ends of the fiber bundle is optically coupled to a lamp or a plurality of lamps 150 ( FIG. 5 ). Light from the lamps is piped through the length of the optical fibers to the ends of the optical fibers in the linear array, from which ends the light is radiated. [0110] FIG. 5 shows, schematically, the construction of light source 114 , in accordance with a preferred embodiment of the invention. In accordance with a preferred embodiment of the invention, a very long strip of the workpiece is to be illuminated, preferably of the order of 660 mm. In order to provide such a long strip of illumination and to assure uniform light intensity along the entire strip, a plurality of light sources, such as high intensity lamps 150 (suitably 250 W HLX reflector type quartz halogen lamps provided by Osram Corporation) are utilized. Each of lamps 150 illuminates a bundle 38 of optical fibers. As shown in FIG. 5 four lamps 150 and four bundles 138 A- 138 D are preferably used for off-axis source 114 . At one end of bundles 138 A- 138 D the fibers are formed into three sets of fiber ends 136 A- 136 C. Each set 136 A- 136 C comprises four layers 156 A- 156 D, each layer being formed from fibers from one of bundles 138 A- 138 D. Thus, each of sets 136 A- 136 C comprises four layers of light fiber ends each layer being illuminated by a different light source. The total light supplied to each of the sets is equal and this equality does not depend on the balance between the light sources. [0111] In a preferred embodiment of the invention, the four layer sets 136 A- 136 C are laid end to end to form a uniform linear light source four fiber layers thick (about 0.56 mm) and over 660 mm long. This light source has been and will continue to be referred herein to as fiber ends 136 . [0112] In an exemplary embodiment of the invention, each fiber bundle includes 17,025 fibers, each having an 80 micrometer diameter. Suitable optical fiber bundles are available from the Schott Company of Germany. [0113] Light source 122 is produced in a manner similar to that employed in the production of source 114 , except that only two fiber bundles and associated lamps are employed. Thus each of the three sections 136 is constructed of only two layers (one from each bundle) and the light source is only 0.28 mm thick. [0114] In the preferred embodiment of the light source according to the invention shown in FIG. 3 , light radiated from the fiber ends 136 is incident on a diffuser 140 which is parallel to the array of fiber ends 136 and substantially perpendicular to central light rays in a substantially wedge shaped beam of light radiated by the array of fiber ends. [0115] The light incident on the diffuser produces an illuminated band on the diffuser that is defined by a width, and on passing through the diffuser the light appears to emanate from a magnified virtual linear light source behind the diffuser. [0116] The present inventors have found, using a ray tracing technique as illustrated in FIG. 4 , that, in fact, the apparent source of the illumination is neither diffuser surface 140 nor the fiber ends 136 . Rather, the light actually appears to be emanating from a virtual light source 142 located behind actual source. However, the present inventors have surprisingly found that the position and width of an effective light source is different from that of both fiber ends 136 and the virtual source 142 . Rather it is defined by a long four sided strip 144 which is referred to herein as a “virtual effective source.” This source is situated between the virtual linear light source 142 and the diffuser 140 . The size and location of the virtual source is determined mainly by the width 151 of the illuminated band on the diffuser and the aperture 152 of the elliptically cylindrical mirror, for the off-axis source and the strip mirror for the on-axis source. It is also affected by the diffusing angle δ of the diffuser. While the workpiece is actually illuminated by light outside of the virtual light source, this light supplies uneven illumination since it is vignetted because not all of it passes through the aperture of the system. [0117] The virtual effective light source is thus that source which provides substantially unvignetted illumination of the workpiece, and for the purposes of illuminating the workpiece, provides desirable lighting. Preferably, the one focus of reflector 112 is optically coincident with the virtual source 144 (after correction for the effect of substrate 120 for the off-axis source), as a result of which the uniformity of intensity of concentrated illumination of the strip on the workpiece across the width of the strip is improved. Light emerging from regions far from the focus of the reflector and especially from outside the virtual effective source are not in focus at the workpiece surface. [0118] Aberrations in optical elements of an illuminator constructed according to the teachings herein generally distort and blur the image of the effective light source. This effect further limits the region of the workpiece which is uniformly illuminated, i.e. the region that receives light from all parts of the illuminating aperture within the angle ±(β±γ/2). The effect of the aberrations is to partially eclipse parts of the illuminating aperture. Generally, off-axis illumination is more susceptible to distortion than on-axis illumination because larger optical apertures and incidence angles are used to focus off-axis illumination than on-axis illumination. For example, in prior art illuminators two separate optical systems are generally used for off-axis illumination while only one optical system is used to focus on-axis illumination. [0119] In order to accommodate aberrations and compensate for their effects, in accordance with a preferred embodiment of the present invention, the widths of the on- and off-axis sources are different so that strips that are illuminated by on- and off-axis illumination on a workpiece being inspected are wider than would be needed in the absence of aberrations. The required width of each respective source is determined by tracing rays from the required region on the workpiece back to the source plane through all optics, while accounting for production tolerances. The required source width should encompass all such back traced rays. A relatively uniform illuminated strip within the “widened” on- and off-axis strips is located and used for inspection of the workpiece. The positions of the fiber ends 36 and their distance from the diffuser is chosen to provide an effective light source having an extent which provides the desired width of illumination of the surface of the workpiece by the on-axis and off-axis illumination. [0120] As indicated above the off-axis illumination is more susceptible to distortion than the on-axis illumination. In accordance with a preferred embodiment of the present invention, the width of the off-axis illumination source is preferably larger than the width of the on-axis source so that the off-axis illumination illuminates a wider strip on the workpiece than the higher quality on-axis illumination. The area in which the on-axis and off-axis illumination overlaps is scanned to locate an optimum, relatively straight, distortion free illuminated strip appropriately illuminated by on- and off-axis illumination. This optimum illuminated strip (generally narrower than the strip illuminated by the on-axis illumination) is the strip on which the collecting optics of an imaging system used to inspect the workpiece are focused and which is imaged on the detectors. [0121] This scanning is performed in the absence of a workpiece using a microscope which images light radiated by the on- and off-axis illumination sources in the region where both sources are concentrated in order to illuminate a strip on a workpiece. The microscope is controlled to travel the length of the region where the on- and off-axis illumination are concentrated and the position of the microscope is accurately monitored as it moves. Light from the on- and off-axis sources imaged by the microscope is analyzed to determine the size and location of an optimum illuminated strip on which to focus the collecting optics of an imaging system. [0122] From the above discussion it is seen that an illuminator, in accordance with a preferred embodiment of the present invention, comprises a reduced number of optical elements and/or elements which are easier to fabricate and/or are easier to assemble into the illuminator, in comparison to most prior illuminators. An illuminator, in accordance with a preferred embodiment of the present invention, provides separately adjustable on-axis illumination and substantially symmetric off-axis illumination for all points in an illuminated strip using two light sources and a single focusing system. Prior art illuminators which provide separate adjustment of the on-axis and off-axis illumination generally use at least three light sources, each with its own focusing system. As a result, an illuminator in accordance with a preferred embodiment of the present invention is comparatively simple, and requires machining tolerances for components that are generally not as severe as the tolerances required for components used in prior art illuminators. [0123] An immediate benefit of these advantages is not only the potentially reduced manufacturing costs. An illuminator in accordance with a preferred embodiment of the present invention is capable of providing illumination for strips on a workpiece that are much longer than those that can be effectively illuminated by prior art illuminators. This enables large workpieces that according to prior art required at least two passes through an inspection system to be inspected, completely inspected, in accordance with a preferred embodiment of the present invention, in a single pass through an inspection system. The inventors of the present invention have found that an illuminator in accordance with a preferred embodiment of the present invention can provide effective illumination for a strip on a workpiece having a length greater than 60 cm. [0124] A block diagram illustration of a system for the inspection of printed circuit boards (PCBs) preferably implementing an illuminator constructed in accordance with a preferred embodiment of the illuminator is shown in FIG. 6 . [0125] An inspection system 200 , shown in FIG. 6 , comprises an optical array 260 comprising a plurality of illuminators 10 each with their respective collecting optics 24 ( FIG. 1 ). [0126] A conveyor 262 is arranged to transport workpieces, such as PCBs 264 , to be inspected past optical array 260 in a transport direction indicated by an arrow 266 . A suitable conveyor for use in a preferred embodiment is described in U.S. patent application Ser. No. 09/010,582 and EP Patent application 97300521.8, the disclosures of which is incorporated herein by reference. Inputs comprising a sequence of optical images of strips of the PCB 264 scanned as it passes under optical array 260 are transferred to a computer 268 . 1 In a preferred embodiment of the invention, optical array 260 is comprised of three illuminator units 10 , each unit including separate collecting optics 24 ( FIG. 1 ). Each of CCD lines 25 - 27 comprises a discontinuous line of detectors. The separate collector optics image a linear segment of the workpiece surface onto one of the sections of line detectors 25 - 27 . Preferably the respective fields of view of the collector optics overlap somewhat so that the sections may be referenced to each other or more preferably joined into a complete image of the workpiece. The combined fields of view of the collector optics preferably extend across substantially the entire width of conveyor 260 . [0127] Furthermore, it will be noted that in a preferred embodiment of the invention, the three CCD lines 25 , 26 and 27 each represent Red, Green and Blue color spectrums respectively, and are offset such that they image slightly offset lines on the illuminated portion of the workpiece. Thus as the workpiece moves beneath the illuminating source, the images acquired by the lines of detectors will be offset by the spacing of the lines of detectors. In accordance with preferred embodiments of the invention, these multi-color images, as well as the relative offsets of the collector optics, are realigned by computer processing, which takes into account both the spacing of lines 25 , 26 and 27 and the velocity of PCB 264 . [0128] Image reconstruction and subsequent processing is performed by computer 268 . Optical Correction Circuitry 270 is provided to reconstruct an image of the inspected PCB and compensate for optical aberrations in acquired images. In a process, typically performed periodically, an inspection test is conducted on system 200 using a test pattern of known configuration. The results from scanning the test pattern are processed to determine optical aberrations, preferably including the respective spatial alignment of images acquired from optical arrays 260 , image overlap, differences in accumulation times and the like. Necessary corrections are computed off-line and the results are stored in a Mapping Function Generator. 272 During on-line inspection, optical correction data stored in the Mapping Function Generator 272 is supplied Optical Correction Circuitry 270 and used to effect optical correction of the images acquired from optical array 260 and to reconstruct an optically corrected image of the inspected PCB. [0129] Optical Correction Circuitry 270 provides a corrected sensor array output to Image Pre-Processing Circuitry 274 . Image Pre-Processing Circuitry 274 preferably provides a segmentation output indication dividing all areas on the image represented by the corrected sensor array output into categories. For example, in the case of PCBs, every location on the image represented by the corrected sensor array output is identified by the segmentation output indication as being either laminate or conductor. Additionally, Image Pre-Processing circuitry 274 may provide a separate segmentation information based on predetermined gray-scale thresholds in certain color spectra, for example thereby additionally segmenting regions suspected of being oxidized or non-oxidized copper. [0130] A segmentation output indication from Image Pre-Processing Circuitry 274 is supplied to Image Processing Circuitry 276 . Image Processing Circuitry 276 provides an image processing output which identifies various features of the image on the PCB and their respective locations. In the case of printed circuit boards, the features are typically pads, conductor junctions and conductive paths, vias and the like, as well as indications of their width, shorts and discontinuities therein. Image Processing Circuitry is preferably a morphology based system, but may alternatively be bit map, net list, design rule or contour based, or based on any other suitable input or combination of the above. [0131] An image processing output of Image Processing Circuitry 276 is supplied to Feature List Registration Circuitry 278 , which maps the coordinate system of the output of Image Processing circuitry 276 onto a reference coordinate system. This registration mapping may be tuned dynamically using dynamic registration methods known in the art in accordance with information supplied by a Feature Reference Source 280 , such as, for example, that described in U.S. Pat. No. 5,495,535. [0132] An output of Feature List Registration circuitry 278 and an output of Feature Reference Source 280 are supplied to Feature Comparison Circuitry 282 , which circuitry compares the now registered map of output of Image Processing Circuitry with a reference stored in Feature Reference Source 280 and provides an output indication of defects. Such defects, in the context of printed circuit board inspection, may typically include absence of required features, the existence of unnecessary features, shorts or discontinuities in connectors, incorrectly shaped features, oxidation and the like defects. An output of the Feature Comparison Circuitry 282 is supplied to a Defect Output Generator Circuitry 284 that prepares a report of defects found on the PCB, which may then be used to assist in manually inspection of defective regions on the PCB. As appropriate, defective PCBs may be repaired or discarded. [0133] While certain features of inspection system 200 have been indicated as being performed by hardware, it should be understood that such features may be performed by software, firmware or combinations of the software and firmware. Furthermore, the functions may be performed utilizing combinations of software, firmware and dedicated hardware. [0134] While the invention has been described with reference to certain preferred embodiments, various modifications will be readily apparent to and may be readily accomplished be persons skilled in the art without departing from the spirit and the scope of the above teachings. In particular, certain embodiments of the invention may not have all of the features of the above described embodiments and further some embodiments of the invention may combine features described above with reference to different embodiments of the invention. Therefore, it is understood that the invention may be practiced other than as specifically described herein without departing from the scope of the following claims:

Illuminating apparatus for illuminating a workpiece during visual inspection thereof, including a first light source emitting light over a continuous angle of illumination toward the workpiece, blocking element arranged to block light over a portion of the continuous angle such that two portions of the illumination, separated by a blocked angle, illuminate the workpiece from the source, and a second light source arranged to illuminate the workpiece over the blocked angle.

TECHNICAL FIELD OF THE INVENTION The present invention relates to the therapeutical application of antiplatelet α-methylene-γ-butyrolactones. BACKGROUND OF THE INVENTION Cardiovascular diseases, especially various forms of thrombosis, such as coronary, embolic, venous and traumatic thrombosis, account for a large number of death per year. In fact it is estimated by the American Heart Association that 54% of all deaths in the United States can be attributed to cardiovascular disease. It is therefore important for us to be familiar with physical, chemical and clinical aspects of drugs used to treat these form of thrombosis. Since it is believed that initiation of thrombus formation is dependent on platelet aggregation, the inhibitors of platelet aggregation could be prototypes for drugs that are more effectively combat thrombosis that leads to heart attacks and strokes. It was therefore prompted us to search for novel compounds possessing more potent inhibiting activity on platelet aggregation. Coumarin derivatives such as bishydroxycoumarin and warfarin are the principal anticoagulants. Other clinically useful antiplatelet drugs are aspirin, eicosapentanoic acid (EPA), dipyridamole, dazoxiben, and ticlopidine. Their utilization is, however, limited by the potency and the side effects. This invention describes the preparation of α-methylene-γ-butyrolactone-containing coumarins, quinolines, and quinolinones from commercially available starting materials in an efficient route. The products describes herein are suitable for large-scale production and exhibit very strong and extensive antiplatelet activity. DETAILED DESCRIPTION OF THE INVENTION This invention included the preparation and the antiplatelet evaluation of novel α-methylene-γ-butyrolactones which have been proved to be potent inhibitors of platelet aggregation. These active compounds, as free type or their pharmaceutically acceptable salts, may be administered parenterally or orally in a suitable pharmaceutical form. They also may be administered along or in conjunction with other antiplatelet agents, in combination with any pharmaceutically acceptable carrier. As used herein, the pharmaceutically acceptable salts include salts with inorganic acids, such as hydrochloride, hydrobromide, sulfate and phosphate; those organic acids, such as acetate, maleate, tartrate, methanesulfonate; and those with amino acids, such as arginine, aspartic acid and glutamic acid. Suitable pharmaceutical forms include sterile aqueous solutions or dispersions, sterile powders, tablets, troches, pills, capsules, and the like. In addition, the active compounds may be incorporated into sustained-release preparations and formulations. The pharmaceutically acceptable carrier includes any and all solvents, disintegrating agents, binders, excipients, lubricants, absorption delaying agents and the like. Although the compound of the present invention may also be present as a hydrate or as a stereoisomer, it is a matter of course that these hydrates and stereoisomers are also included in the scope of the present invention. The new compounds can be prepared according to the following reaction schemes and protocols. PART A Preparation of 4-[(2, 3, 4, 5-Tetrahydro-3-methylene-2-oxo-5-furanyl) methoxy]-2H-1-benzopyran-2-ones (Scheme 1) ##STR2## The commercially available 4-hydroxycoumarin was treated with potassium carbonate and a haloketone (chloroacetone, R 1 =CH 3 ; 2-bromoacetophenone, R 1 =C 6 H 5 ; 2-bromo-4'-fluoroacetophenone, R 1 =C 6 H 4 F; 2-bromo-4'-chloroacetophenone, R 1 =C 6 H 4 Cl; 2-bromo-4'-bromoacetophenone, R 1 =C 6 H 4 Br; 2-bromo-4'-iodoacetophenone, R 1 =C 6 H 4 I; 2-bromo-4'-methylacetophenone, R 1 =C 6 H 4 CH 3 ; 2-bromo-4'-nitroacetophenone, R 1 =C 6 H 4 NO 2 ; 2-bromo-4'-methoxyacetophenone, R 1 =C 6 H 4 OCH 3 ; 2-bromo-4'-phenylacetophenone, R 1 =C 6 H 4 C 6 H 5 ) in acetone or N,N,-dimethylformamide (DMF) to provide (2'-oxoethoxy)-2H-1-benzopyran-2-ones which were reacted with ethyl 2-(bromomethyl)acrylate in tetrahydrofuran (THF) (Reformatsky reaction) to produce 4-[(2,3,4,5-tetrahydro-3-methylene-2-oxo-5-furanyl)methoxy]-2H-1-benzopyran-2-ones (I). EXAMPLE 1 4-[(2,3,4,5-Tetrahydro-2-methyl-4-methylene-5-oxo-2-furanyl)methoxy]-2H-1-benzopyran-2-one (1) To a solution of 4-hydroxycoumarin (1.62 g, 10 mmol) in acetone (20 ml) were added potassium carbonate (5.53 g, 40 mmol) and chloroacetone (1.38 g, 15 mmol). The resulting mixture was refluxed for 4 h. (monitored by TLC). Evaporation of the solvent gave a residue which was poured into ice water (50 ml). The resulting solid was collected and crystallized from ethyl acetate to afford 4-(2-Oxopropoxy)-2H-1-benzopyran-2-one (1a) (1.28 g, 55.1%) as a white needle crystal. mp: 163°-165° C.; IR(KBr) ν max : 1716, 1625; UV(CHCl 3 ) λ max (log ε): 305 (3.83), 266 (4.05); 1 H-NMR (CDCl 3 ): δ2.36 (s, 3H, CH 3 ), 4.77 (s, 2H, OCH 2 ), 5.57 (s, 1H, 3-H), 7.28-7.36 (m, 2H, 6- and 8-H), 7.54-7.63 (m, 1H, 7-H), 7.88-7.94 (m, 1H, 5-H). Anal. Calcd for C 12 H 10 O 4 : C, 66.05; H, 4.62. Found: C, 66.01; H, 4.64. To a solution of 1a (0.655 g, 3 mmol) in dry tetrahydrofuran (60 ml) were added activated zinc powder (0.255 g, 3.9 mmol), hydroquinone (6 mg), and ethyl 2-(bromomethyl)acrylate (0.78 g, 4 mmol). The mixture was reflued under nitrogen atmosphere for 36 h. (monitored by TLC). After cooling it was poured into an ice-cold 5% HCl solution (300 ml) and extracted with CH 2 Cl 2 (75 ml×3). The dichloromethane extracts were combined and washed with saline, dried over Na 2 SO 4 , and then evaporated to give a residual solid which was crystallized from ethyl acetate to afford the title compound (0.656 g, 76.4%) as a pale yellow crystal. mp: 161°-162° C.; IR(KBr) ν max : 1766, 1703, 1627; UV (CHCl 3 ) λ max (log ε): 306 (3.79), 276 (4.01), 266 (4.05); 1 H-NMR (CDCl 3 ): δ1.64 (s, 3H, 5'-CH 3 ), 2.88 (dt, 1H, 4'-H), 3.19 (dt, 1H, 4'-H), 4.08, 4.20 (two d, 2H, OCH 2 ), 5.67 (s, 1H, 3-H), 5.75 (t, 1H, vinylic H), 6.38 (t, 1H, vinylic H), 7.12-7.33 (m, 2H, 6 and 8-H), 7.51-7.65 (m, 2H, 5 and 7-H). Anal. Calcd for C 16 H 14 O 5 : C, 67.13; H, 4.93. Found: C, 67.14; H, 5.01. EXAMPLE 2 4-[(2,3,4,5-Tetrahydro-4-methylene-5-oxo-2-phenyl-2-furanyl)methoxy]-2H-1-benzopyran-2-one (2) To a solution of 4-hydroxycoumarin (1.62 g, 10 mmol) in acetone (60 ml) were added 2-bromoacetophenone (1.99 g, 10 mmol) and potassium carbonate (5.53 g, 40 mmol). The mixture was refluxed for 3 h. (monitored by TLC). Evaporation of the solvent gave a residue which was poured into ice water (50 ml). The resulting solid was collected and crystallized from ethyl acetate to afford 4-(2-Oxo-2-phenylethoxy)-2H-1-benzopyran-2-one (2a) (1.76 g, 62.9%) as a needle crystal. mp: 183°-184° C.; IR(KBr) ν max : 1721, 1703, 1626; UV(CHCl 3 ) λ max (log ε): 306 (3.79), 253 (4.28); 1 H-NMR (CDCl 3 ): δ5.50 (s, 2H, OCH 2 ), 5.61 (s, 1H, 3-H), 7.26-7.35 (m, 2H, 6- and 8-H), 7.50-7.71 (m, 4H, 5-, 7-H and aromatic H), 7.94-8.02 (m, 3H, aromatic H). Anal. Calcd for C 17 H 12 O 4 : C, 72.85; H, 4.32. Found: C, 72.85; H, 4.72. To a solution of 2a (0.84 g, 3 mmol) in dry tetrahydrofuran (60 ml) were added activated zinc powder (0.255 g, 3.9 mmol), hydroquinone (6 mg), and ethyl 2-(bromomethyl)acrylate (0.78 g, 4 mmol). The mixture was refluxed under nitrogen atmosphere for 18 h. (monitored by TLC). After cooling it was poured into an ice-cold 5% HCl solution (300 ml) and extracted with CH 2 Cl 2 (75 ml×3). The dichloromethane extracts were combined and washed with saline, dried over Na 2 SO 4 , and then evaporated to give a residual solid which was crystallized from ethyl acetate to afford the title compound (0.90 g, 86.4%). mp: 212°-214° C.; IR(KBr) ν max : 1766, 1717, 1620; UV(CHCl 3 ) ν max (log ε): 306 (3.89), 277 (4.10), 266 (4.14); 1 H-NMR (CDCl 3 ): δ3.33 (dt, 1H, 4'-H), 3.66 (dt, 1H, 4'-H), 4.26, 4.32 (two d, 2H, OCH 2 ), 5.60 (s, 1H, 3-H), 5.79 (t, 1H, vinylic H), 6.42 (t, 1H, vinylic H), 7.20-7.61 (m, 9H, 5,6,7,8-H, and aromatic H). Anal. Calcd for C 21 H 16 O 5 0.25H 2 O: C, 71.48; H, 4.71. Found: C, 71.37; H, 4.67. PART B Preparation of [(2,3,4,5-Tetrahydro-3-methylene-2-oxo-5-furanyl) methoxy]-2H-1-benzopyran-2-ones (Scheme 2) ##STR3## Each of the hydroxycoumarins (R 2 =H, Cl, CH 3 ; R 3 =H, Cl, CH 3 ) was treated with potassium carbonate and a haloketone (chloroacetone, R 1 =CH 3 ; 2-bromoacetophenone, R 1 =C 6 H 5 ; 2-bromo-4'-fluoroacetophenone, R 1 =C 6 H 4 F; 2-bromo-4'-chloroacetophenone, R 1 =C 6 H 4 Cl; 2-bromo-4'-bromoacetophenone, R 1 =C 6 H 4 Br; 2-bromo-4'-iodoacetophenone, R 1 =C 6 H 4 I; 2-bromo-4'-methylacetophenone, R 1 =C 6 H 4 CH 3 ; 2-bromo-4'-nitroacetophenone, R 1 =C 6 H 4 NO 2 ; 2-bromo-4'-methoxyacetophenone, R 1 =C 6 H 4 OCH 3 ; 2-bromo-4'-phenylacetophenone, R 1 =C 6 H 4 C 6 H 5 ) in acetone or DMF to provide (2'-oxoethoxy)-2H-1-benzopyran-2-ones which were reacted with ethyl 2-(bromomethyl)acrylate in tetrahydrofuran (THF) (Reformatsky reaction) to produce [(2,3, 4,5-tetrahydro-3-methylene-2-oxo-5-furanyl)methoxy]-2H-1-benzopyran-2-ones (II). EXAMPLE 3 7-[(2,3,4,5-Tetrahydro-2-methyl-4-methylene-5-oxo-2-furanyl)methoxy]-2H-1-benzopyran-2-one (3) To a solution of 7-hydroxycoumarin (1.62 g, 10 mmol) in acetone (20 ml) were added potassium carbonate (5.53 g, 40 mmol) and chloroacetone (1.38 g, 15 mmol). The resulting mixture was refluxed for 4 h. (monitored by TLC). Evaporation of the solvent gave a residue which was poured into ice water (50 ml). The resulting solid was collected and crystallized from ethyl acetate to afford 7-(2-oxopropoxy)-2H-1-benzopyran-2-one (3a) (2.10 g, 96.1%) as a white needle crystal. mp: 165°-167° C.; IR(KBr) ν max : 1709, 1620; UV(CHCl 3 ) λ max (log ε): 308 (4.14), 244 (3.52); 1 H-NMR (CDCl 3 ): δ2.31 (s, 3H, CH 3 ), 4.65 (s, 2H, OCH 2 ), 6.29 (d, 1H, 3-H), 6.76 (d, 1H, 8-H), 6.88 (dd, 1H, 6-H), 7.42 (d, 1H, 5-H), 7.65 (d, 1H, 4-H). Anal. Calcd for C 12 H 10 O 4 : C, 66.05; H, 4.62. Found: C, 65.98; H, 4.61. To a solution of 3a (0.655 g, 3 mmol) in dry tetrahydrofuran (60 ml) were added activated zinc powder (0.255 g, 3.9 mmol), hydroquinone (6 mg), and ethyl 2-(bromomethyl)acrylate (0.78 g, 4 mmol). The mixture was reflued under nitrogen atmosphere for 36 h. (monitored by TLC). After cooling it was poured into an ice-cold 5% HCl solution (300 ml) and extracted with CH 2 Cl 2 (75 ml×3). The dichloromethane extracts were combined and washed with saline, dried over Na 2 SO 4 , and then evaporated to give a residual solid which was crystallized from ethyl acetate to afford the title compound; Yield: 79.7%; mp: 123°-124° C.; IR(KBr) ν max : 1755, 1727, 1626; UV(CHCl 3 ) λ max (log ε): 312 (4.18), 243 (3.58); 1 H-NMR (CDCl 3 ): δ1.58 (s, 3H, 5'-CH 3 ), 2.79 (dt, 1H, 4'-H), 3.18 (dt, 1H, 4'-H), 3.99, 4.09 (two d, 2H, OCH 2 ), 5.69 (t, 1H, vinylic H), 6.26 (d, 1H, 3-H), 6.29 (t, 1H, vinylic H), 6.76-6.84 (m, 2H, 6 and 8-H). 7.38 (d, 1H, 5-H), 7.65 (d, 1H, 4-H). Anal Calcd for C 16 H 14 O 5 : C, 67.13; H, 4.93. Found: C, 66.95; H. 5.10. EXAMPLE 4 7-[(2,3,4,5-Tetrahydro-4-methylene-5-oxo-2-Phenyl-2-furanyl)methoxy]-2H-1-benzopyran-2-one (4) To a solution of 7-hydroxycoumarin (1.62 g, 10 mmol) in acetone (60 ml) were added 2-bromoacetophenone (1.99 g, 10 mmol) and potassium carbonate (5.53 g, 40 mmol). The mixture was refluxed for 3 h. (monitored by TLC). Evaporation of the solvent gave a residue which was poured into ice water (50 ml). The resulting solid was collected and crystallized from ethyl acetate to afford 7-(2-oxo-2-phenylethoxy)-2H-1-benzopyran-2-one (4a) (1.53 g, 73.1%) as a needle crystal. mp: 163°-165° C.; IR(KBr) ν max : 1728, 1702, 1627; UV(CHCl 3 ) λ max (log ε): 320 (4.16), 249 (4.13); 1 H-NMR (CDCl 3 ): δ5.39 (s, 2H, OCH 2 ), 6.27 (d, 1H, 3-H), 6.80 (d, 1H, 8-H), 6.93 (dd, 1H, 6-H), 7.40 (d, 1H, 5-H), 7.49-7.68 (m, 4H, 4-H and aromatic H). Anal Calcd for C 17 H 12 O 4 : C, 72.85; H, 4.32. Found: C, 72.98; H, 4.35. To a solution of 4a (0.84 g, 3 mmol) in dry tetrahydrofuran (60 ml) were added activated zinc powder (0.255 g, 3.9 mmol), hydroquinone (6 mg), and ethyl 2-(bromomethyl)acrylate (0.78 g, 4 mmol). The mixture was refluxed under nitrogen atmosphere for 18 h. (monitored by TLC). After cooling it was poured into an ice-cold 5% HCl solution (300 ml) and extracted with CH 2 Cl 2 (75 ml×3). The dichloromethane extracts were combined and washed with saline, dried over Na 2 SO 4 , and then evaporated to give a residual solid which was crystallized from ethyl acetate to afford the title compound; Yield: 77.8%; mp: 105°-106° C.; IR(KBr) ν max : 1758, 1719, 1616; UV(CHCl 3 ) λ max (log ε): 321 (4.22), 243 (3.62); 1 H-NMR (CDCl 3 ): δ3.24 (dt, 1H, 4'-H), 3.66(dt, 1H, 4'-H), 4.17, 4.24 (two d, 2H, OCH 2 ), 5.71 (t, 1H, vinylic H), 6.24 (d, 1H, 3-H), 6.31 (t, 1H, vinylic H), 6.72 (d, 1H, 8-H), 6.78 (dd, 1H, 6-H), 7.35 (d, 1H, 5-H), 7.40-7.52 (m, 5H, aromatic H), 7.62 (d, 1H, 4-H). Anal Calcd for C 21 H 16 O 5: C, 72.41; H, 4.63. Found: C, 72.30; H, 4.67. PART C Preparation of 2-Substituted [(2,3,4,5-Tetrahydro-3-methylene-2-oxo-5-furanyl)methoxy]quinolines (Scheme 3) ##STR4## Each of the hydroxyquinolines (R 4 =H, OH, CH 3 ) was treated with potassium carbonate and a haloketone (chloroacetone, R 1 =CH 3 ; 2-bromoacetophenone, R 1 =C 6 H 5 ; 2-bromo-4'-fluoroacetophenone, R 1 =C 6 H 4 F; 2-bromo-4'-chloroacetophenone, R 1 =C 6 H 4 Cl; 2-bromo-4'-bromoacetophenone, R 1 =C 6 H 4 Br; 2-bromo-4'-iodoacetophenone, R 1 =C 6 H 4 I; 2-bromo-4'-methylacetophenone, R 1 =C 6 H 4 CH 3 ; 2-bromo-4'nitroacetophenone, R 1 =C 6 H 4 NO 2 ; 2-bromo-4'-methoxyacetophenone, R 1 =C 6 H 4 OCH 3 ; 2-bromo-4'-phenylacetophenone, R 1 =C 6 H 4 C 6 H 5 ) in DMF or acetone to provide 2-substituted (2'-oxoethoxy)quinolines which were reacted with ethyl 2-(bromomethyl)acrylate in THF to produce 2-substituted [(2,3,4,5-tetrahydro-3-methylene-2-oxo-5-furanyl)methoxy]quinolines (III). EXAMPLE 5 8-[(2,3,4,5-Tetrahydro-2-methyl-4-methylene-5-oxo-2-furanyl)methoxy]-2(1H)-quinolinone (5) To a solution of 8-hydroxyquinoline (1.45 g, 10 mmol) in dichloromethane (50 ml) was added 3-chloroperbenzoic acid (MCPBA) (1.24 g, 13 mmol). The mixture was stirred at room temperature for 10 min, poured into 1.0N sodium bicarbonate (100 ml), and then extracted with dichloromethane (3×50 ml). The extract was washed with water, dried over magnesium sulfate, and evaporated to give a brown solid which was crystallized from dichloromethane and diethyl ether affording 8-Hydroxyquinoline 1-oxide (5a) (1.34 g, 83%) as yellow needle crystals. mp: 132°-133° C.; 1 H-NMR (CDCl 3 ): δ7.04-8.28 (m, 6H, Ar--H), 15.02 (br s, 1H, OH). A mixture of 5a (0.81 g, 5 mmol) in acetic anhydride (20 ml) was heated at reflux for 2 h (monitored by TLC). After cooling, it was poured into ice water (100 ml). The resulting solid was collected and crystallized from dichloromethane to give 2-Acetoxy-8-hydroxyquinoline (5b) (0.85 g, 84%) as white crystals. mp: 240°-241° C.; 1 H-NMR (DMSO-d 6 ): δ2.55; (s, 3H, CH 3 ), 6.66 (d, 3-H), 7.15-7.23 (m, 3H, Ar--H), 7.78 (d, 4-H), 11.31 (br s, 1H, OH). A mixture of 5b (1.02 g, 5 mmol), potassium carbonate (0.69 g, 5 mmol) and dry N,N-dimethylformamide (DMF) (40 ml) was stirred at room temperature for 30 min and then chloroacetone (0.46 g, 5 mmol) in dry THF (10 ml) was added in one portion. The resulting mixture was continued to stir at room temperature for 24 h (monitored by TLC). After this period, it was poured into ice water (100 ml) and the pale yellow solid thus obtained was crystallized from dichloromethane and ether to afford 2-Acetoxy-8-(2-oxopropoxy)quinoline (5c) (0.85 g, 66%). mp: 79°-80° C.; 1 H-NMR (CDCl 3 ): δ2.16 (s, 3H, OAc), 2.42 (s, 3H, 3'-CH 3 ), 4.85 (s, 2H, OCH 2 ), 7.06 (d, 3-H), 7.26-7.67 (m, 3H, Ar--H), 8.08 (d, 4-H). To a solution of 5c (0.78 g, 3 mmol) in dry tetrahydrofuran (60 ml) were added activated zinc powder (0.26 g, 3.9 mmol), hydroquinone (6 mg), and ethyl 2-(bromomethyl)acrylate (0.78 g, 4 mmol). The mixture was refluxed under nitrogen atmosphere for 6 h (monitored by TLC). After cooling, it was poured into an ice-cold 5% HCl solution (300 ml), neutralized with 1.0N NaHCO 3 , and extracted with CH 2 Cl 2 (75 ml×3). The dichloromethane extracts were combined and washed with water, dried over Na 2 SO 4 , and then evaporated to give a residual oil which was purified by column chromatography on silica gel using CH 2 Cl 2 as the eluent to afford the title compound (0.59 g, 60%). UV λ max (log ε): 258 (4.70) (0.1N HCl in MeOH), 246 (4.69) (MeOH), 261 (4.59) (0.1N NaOH in MeOH); 1 H-NMR (CDCl 3 ): δ1.61 (s, 3H, 2'-CH 3 ), 2.78 (dt, 1H, 3'-H), 3.17 (dt, 1H, 3'-H), 4.50 (s, 2H, OCH 2 ), 5.65 (t, 1H, vinylic H), 6.29 (t, 1H, vinylic H), 6.91 (d, 1H, 3-H), 7.18-7.41 (m, 3H, Ar--H), 8.02 (d, 1H, 4-H). Anal Calcd for C 16 H 15 NO 4 : C, 67.36; H, 5.30; N, 4.91. Found: C, 67.38; H, 5.32; N, 5.00. EXAMPLE 6 8-[(2,3,4,5-Tetrahydro-4-methylene-5-oxo-2-phenyl-2-furanyl)methoxy]-2(1H)-quinolinone (6) 2-Acetoxy-8-(2-oxo-2-phenylethoxy)quinoline (6a) was prepared from 2-acetoxy-8-hydroxyquinoline (5b) and 2-bromoacetophenone by the same procedure as 5c in 74% yield. mp: 141°-142° C.; 1 H-NMR (CDCl 3 ): δ1.92 (s, 3H, CH 3 ), 5.66 (s, 2H, OCH 2 ), 7.11 (d, 3-H), 7.25-8.04 (m, 8H, Ar--H), 8.05 (d, 4-H). The title compound was prepared from 6a by the same procedure as 5 in 57% yield. UV λ max (log ε): 260 (4.69) (0.1N HCl in MeOH), 247 (4.73) (MeOH), 261 (4.61) (0.1N NaOH in MeOH); 1 H-NMR (CDCl 3 ): δ3.23 (dt, 1H, 3'-H), 3.63 (dt, 1H, 3'-H), 4.63 (d, 1H, OCH), 4.71 (d, 1H, OCH), 5.66 (t, 1H, vinylic H), 6.30 (t, 1H, vinylic H), 6.88 (d, 1H, 3-H), 7.15-7.52 (m, 8H, Ar--H), 8.00 (d, 1H, 4-H). Anal. Calcd for C 21 H 17 NO 4 : C, 72.61; H, 4.93; N, 4.03. Found: C, 72.69; H, 4.94; N, 4.11. EXAMPLE 7 8-[(2,3,4,5-Tetrahydro-2-methyl-4-methylene-5-oxo-2-furanyl)methoxy]quinoline (7) 8-Hydroxyquinoline (0.73 g, 5 mmol), potassium carbonate (0.69 g, 5 mmol) and dry N,N-dimethylformamide (DMF) (40 ml) were stirred at room temperature for 30 min. To this solution was added chloroacetone (0.46 g, 5 mmol) in dry THF (10 ml) in one portion. The resulting mixture was stirred at room temperature for 24 h. (monitored by TLC) and then poured into ice water (100 ml). The pale yellow solid thus obtained was collected and crystallized from dichloromethane and ether to afford 8-(2-oxopropoxy)quinoline (7a) (0.68 g, 67%) as a pale yellow needle crystal. mp: 58°-59° C.; 1 H-NMR (CDCl 3 ): δ2.32 (s, 3H, CH 3 ), 4.88 (s, 2H, OCH 2 ), 6.88-8.97 (m, 6H, Ar--H). To a solution of 7a (0.60 g, 3 mmol) in dry tetrahydrofuran (60 ml) were added activated zinc powder (0.26 g, 3.9 mmol), hydroquinone (6 mg), and ethyl 2-(bromomethyl)acrylate (0.78 g, 4 mmol). The mixture was refluxed under nitrogen atmosphere for 6 h (monitored by TLC). After cooling, it was poured into an ice-cold 5% HCl solution (300 ml), neutralized with 1.0N NaHCO 3 , and extracted with CH 2 Cl 2 (60 ml×3). The dichloromethane extracts were combined and washed with water, dried over Na 2 SO 4 , and then evaporated to give a residual oil which was purified by column chromatography on silica gel using CH 2 Cl 2 as the eluent to afford the title compound (0.66 g, 82%). UV λ max (log ε): 250 (4.69) (0.1N HCl in MeOH), 237 (4.60) (MeOH), 238 (4.64) (0.1N NaOH in MeOH); 1 H-NMR (CDCl 3 ): δ1.61 (s, 3H, 2'-CH 3 ), 2.84 (dt, 1H, 3'-H), 3.48 (dt, 1H, 3'-H), 4.25 (d, 1H, OCH), 4.32 (d, 1H, OCH), 5.66 (t 1H, vinylic H), 6.26 (t, 1H, vinylic H), 7.13-8.91 (m, 6H, Ar--H). Anal. Calcd for C 16 H 15 NO 3 .1/8H 2 O: C, 70.77; H, 5.65; N, 5.16. Found: C, 70.80; H, 5.75; N, 5.08. EXAMPLE 8 8-[(2,3,4,5-Tetrahydro-4-methylene-5-oxo-2-phenyl-2-furanyl)methoxy]quinoline (8) 8-(2-Oxo-2-phenylethoxy)quinoline (8a) was prepared from 2-bromoacetophenone by the same procedure as 7a in 69% yield. mp: 124°-125° C.; 1 H-NMR (CDCl 3 ): δ5.65 (s, 2H, OCH 2 ), 6.95-8.97 (m, 11H, Ar--H). The title compound was prepared from 8a by the same procedure as 7 in 75% yield. mp: 101°-102° C.; UV λ max (log ε): 250 (4.69) (0.1N HCl in MeOH), 237 (4.62) (MeOH), 237 (4.67) (0.1N NaOH in MeOH); 1 H-NMR (CDCl 3 ): δ3.25 (dt, 1H, 3'-H), 4.09 (dt, 1H, 3'-H), 4.46 (d, 1H, OCH), 4.62 (d, 1H, OCH), 5.68 (t, 1H, vinylic H), 6.25 (t, 1H, vinylic H), 7.16-8.90 (m, 11H, Ar--H). Anal. Calcd for C 21 H 17 NO 3 : C, 76.11; H, 5.17; N, 4.23. Found: C, 76.10; H, 5.19; N, 4.27. EXAMPLE 9 8-[(2-(p-Chlorophenyl)-2,3,4,5-tetrahydro-4-methylene-5-oxo-2-furanyl)methoxy]quinoline (9) 8-(2-(p-Chlorophenyl)-2-oxoethoxy)quinoline (9a) was prepared from 2-bromo-4'-chloroacetophenone by the same procedure as 7a in 76% yield. mp: 111°-112° C.; 1 H -NMR (CDCl 3 ): δ5.56 (s, 2H, OCH 2 ), 6.96-8.96 (m, 10 H, Ar--H). The title compound was prepared from 9a by the same procedure as 7 in 69% yield. mp: 107°-108° C.; UV λ max (log ε): 249 (4.75) (0.1N HCl in MeOH), 236 (4.69) (MeOH), 238 (4.28) (0.1N NaOH in MeOH); 1 H-NMR (CDCl 3 ): δ3.20 (dt, 1H, 3'-H), 4.06 (dt, 1H, 3'-H), 4.42 (d, 1H, OCH), 4.56 (d, 1H, OCH), 5.70 (t, 1H, vinylic H), 6.28 (t, 1H, vinylic H), 7.13-8.91 (m, 10H, Ar--H). Anal. Calcd for C 21 H 16 ClNO 3 : C, 68.95; H, 4.41; N, 3.83. Found: C, 68.91; H, 4.44; N, 3.87. EXAMPLE 10 8-[(2,3,4,5-Tetrahydro-2-methyl-4-methylene-5-oxo-2-furanyl)methoxy]-2-methylquinoline (10) 2-Methyl-8-hydroxyquinoline (0.80 g, 5 mmol), potassium carbonate (0.69 g, 5 mmol) and dry N,N-dimethylformamide (DMF) (40 ml) were stirred at room temperature for 30 min. To this solution was added chloroacetone (0.46 g, 5 mmol) in dry THF (10 ml) in one portion. The resulting mixture was stirred at room temperature for 24 h. (monitored by TLC) and then poured into ice water (100 ml). The pale yellow solid thus obtained was collected and crystallized from dichloromethane and ether to afford 2-methyl-8-(2-oxopropoxy)quinoline (10a) (0.77 g, 72%). mp: 99°-100° C.; 1 H-NMR (CDCl 3 ): δ2.35 (s, 3H, 2'-CH 3 ), 2.79 (s, 3H, 2-CH 3 ), 4.86 (s, 2H, OCH 2 ), 6.88-7.44 (m, 3H, Ar--H), 7.33 (d, 1H, 3-H), 8.03 (d, 1H, 4-H). The title compound was prepared from 10a by the same procedure as 7 in 70% yield. UV λ max (log ε): 253 (4.42) (0.1N HCl in MeOH), 238 (4.45) (MeOH), 239 (4.46) (0.1N NaOH in MeOH); 1 H-NMR (CDCl 3 ): δ1.61 (s, 3H, 2'-CH 3 ), 2.71 (s, 3H, 2-CH 3 ), 2.80 (dt, 1H, 3'-H), 3.53 (dt, 1H, 3'-H), 4.24 (d, 1H, OCH), 4.30 (d, 1H, OCH), 5.67 (t, 1H, vinylic H), 6.28 (t, 1H, vinylic H), 7.08-7.42 (m, 3H, Ar--H), 7.26 (d, 1H, 3-H), 7.97 (d, 1H, 4-H). Anal. Calcd for C 17 H 17 NO 3 .1/8H 2 O: C, 71.50; H, 6.09; N, 4.90. Found: C, 71.26; H, 6.13; N, 4.73. EXAMPLE 11 8-[(2,3,4,5-Tetrahydro-4-methylene-5-oxo-2-phenyl-2-furanyl)methoxy]-2-methylquinoline (11) 2-Methyl-8-(2-oxo-2-phenylethoxy)quinoline (11a) was prepared from 2-bromoacetophenone by the same procedure as 10a in 72% yield. mp: 70°-71° C.; 1 H-NMR (CDCl 3 ): δ2.77 (s, 3H, 2-CH 3 ), 5.63 (s, 2H, OCH 2 ), 6.94-8.10 (m, 8H, Ar--H), 7.29 (d, 1H, 3-H), 7.99 (d, 1H, 4-H). The title compound was prepared from 11a by the same procedure as 7 in 61% yield. mp: 108°-109° C.; UV λ max (log ε): 253 (4.53) (0.1N HCl in MeOH), 239 (4.46) (MeOH), 240 (4.51) (0.1N NaOH in MeOH); 1 H-NMR (CDCl 3 ): δ2.74 (s, 3H, CH 3 ), 3.25 (dt, 1H, 3'-H), 4.12 (dt, 1H, 3'-H), 4.41 (d, 1H, OCH), 4.56 (d, 1H, OCH), 5.71 (t, 1H, vinylic H), 6.31 (t, 1H, vinylic H), 7.06-7.60 (m, 8H, Ar--H), 7.27 (d, 1H, 3-H), 7.98 (d, 1H, 4-H). Anal. Calcd for C 22 H 19 NO 3 : C, 76.51; H, 5.54; N, 4.06. Found: C, 76.52; H, 5.55; N, 4.15. EXAMPLE 12 8-[(2-(p-Chlorophenyl)-2,3,4,5-tetrahydro-4-methylene-5-oxo-2-furanyl)methoxy]-2-methylquinoline (12) 8-(2-(p-Chlorophenyl)-2-oxoethoxy)-2-methylquinoline (12a) was prepared from 2-bromo-4'-chloroacetophenone by the same procedure as 10a in 64% yield. mp: 112°-113° C.; 1 H-NMR (CDCl 3 ): δ2.77 (s, 3H, 2-CH 3 ), 5.56 (s, 2H, OCH 2 ), 6.94-8.12 (m, 8H, Ar--H), 7.31 (d, 1H, 3-H), 8.00 (d, 1H, 4-H). The title compound was prepared from 12a by the same procedure as 7 in 68% yield. mp: 129°-130° C.; UV λ max (log ε): 253 (4.62) (0.1N HCl in MeOH), 238 (4.60) (MeOH), 240 (4.61) (0.1N NaOH in MeOH); 1 H-NMR (CDCl 3 ): δ2.74 (s, 3H, CH 3 ), 3.20 (dt, 1H, 3'-H), 4.08 (dt, 1H, 3'-H), 4.37 (d, 1H, OCH), 4.50 (d, 1H, OCH), 5.72 (t, 1H, vinylic H), 6.32 (t, 1H, vinylic H), 7.04-7.58 (m, 7H, Ar--H), 7.27 (d, 1H, 3H), 7.98 (d, 1H, 4-H). Anal. Calcd for C 22 H 18 ClNO 3 : C, 69.56; H, 4.78; N, 3.69. Found: C, 69.51; H, 4.79; N, 3.75. PART D: Antiplatelet activity The pharmacological activity of these compounds were determined according to G.V.R. Born by turbidimetry (J. Physiol., 1963, 168, 178). Based on the method, samples were suspended in rabbit platelets which were washed with platelet-rich plasma, the aggregation was then counted by the Lumi-aggregometer (Model 1020, Paytoon, Canada). The results are shown in Table 1. Formula (I-III) at the concentration of 100 μg/ml are found to inhibit the platelet aggregation perfectly which was induced by arachidonic acid (AA), collagen, ADP, and PAF. Since the structures of these compounds are different from those of known antiplatelet agents, the present invention have the potential for further development. Compounds of this invention may be administered parenterally or orally in a suitable pharmaceutical form. They also may be administered along or in conjunction with other antiplatelet agents, in combination with any pharmaceutically acceptable carrier. As used herein, suitable pharmaceutical forms include sterile aqueous solutions or dispersions, sterile powders, tablets, troches, pills, capsules, and the like. In addition, the active compounds may be incorporated into sustained-release preparations and formulations. The pharmaceutically acceptable carrier for oral dosage form are, in particular, filers, such as sugars, for example, lactose, sucrose, mannitol, and furthermore binders, such as starch mucilage using, for example, wheat, rice or potato starch, and/or, if desired, disintegrating or adjuncts. Those carriers for parenteral dosage form are, in particular, aqueous solutions and furthermore lipophilic solvents or vehicles such as fatty oils, and/or, if desired, viscosity-increasing substance, for example sodium carboxymethyl cellulose, sorbitol. Although the compound of the present invention may also be present as a hydrate or as a stereoisomer, it is a matter of course that these hydrates and stereoisomers are also included in the scope of the present invention. The prefer individual dose is 50 to 300 mg for oral administration and 2 to 15 mg for intravenous administration and can be administered up to 3 times daily. (A) Preparation of platelet aggregation inducers: 1. Bovine thrombin, from the Parke Davis Co., was dissolved in 50% (v/v) glycerol for a stock solution of 100 NIH units/mL. 2. Collagen (type I: bovine Achilles tendon), from the Sigma Chemical Co., was homogenized in 25 mM acetic acid and stored (1 mg/mL) at -70° C. 3. PAF (1-O-alkyl-2-acetyl-sn-glycerol-3-phosphorylcholine), purchased from Sigma, was dissolved in chloroform and diluted into 0.1% BSA-saline solution immediately prior to use. 4. AA (arachidonic acid), purchased from Sigma, was dissolved in deionized water. (B) Preparation of platelets: Platelet suspension was prepared from EDTA-anticoagulated Platelet-rich plasma according to washing procedures described previously (Teng, C. M. et. al., Thromb Haemost 59, 304, 1991). Platelets were counted by Hemalaser 2 (Sebia, France) and adjusted to a concentration of 4.5×10 8 platelets/mL. Platelet pellets were finally suspended in Tyrode's buffer (pH 7.4) of the following composition: NaCl (136.8 mM), KCl (2.8 mM), NaHCO 3 (11.9 mM), MgCl 2 (2.1 mM), NaH 2 PO4 (0.33 mM), CaCl 2 (1 mM), glucose (11.2 mM) containing 0.35% bovine serum albumin. (C) Platelet aggregation and ATP release reaction: Aggregation was measured by the turbidimetry method as described by O'Brien (J Clin Pathol 15, 452, 1962). ATP released from platelets was detected by the bioluminescence method of DeLuca and McElory (Methods Enzymol 57, 3, 1978). Both aggregation and ATP release were measured simultaneously in a Lumi-aggregometer (model 1020B, Payton, Canada) connected to two dt/al-channel recorders. Platelet preparations were stirred at 900 rpm. When DMSO was used as solvent, its final concentration was fixed at 0.5% (v/v) to eliminate the effect of the solvent. For the calculation of percentage aggregation, the absorbance of platelet suspension was designated as 0% aggregation and the absorbance of platelet-free Tyrode's solution as 100% aggregation. The antiplatelet effects were shown in Table 1 and the inhibitory concentrations for 50% aggregation (IC 50 ) were expressed in Table 2. BRIEF DESCRIPTION OF THE DRAWING Table 1. Effect of α-methylene-γ-butyrolactones on the platelet aggregation (%) induced by thrombin (Thr), arachidonic acid (AA), collagen (Col) and platelet-activating factor (PAF) in washed rabbit platelets a Table 2. IC 50 values of α-methylene-γ-butyrolactones on the platelet aggregation induced by Thr (0.1 U/ml), AA (100 μg/ml), Col (10 μg/ml), and PAF (2 nM) TABLE 1__________________________________________________________________________Effect of α-methylene-γ-butyrolactones on the plateletaggregation (%)induced by thrombin (Thr), arachidonic acid (AA), collagen (Col) andplatelet-activating factor (PAF) in washed rabbit platelets.sup.aInducerCompds Thr 0.1 U/ml AA 100 μM Col 10 μg/ml PAF 2 nM__________________________________________________________________________Control 91.7 ± 1.0(5) 86.4 ± 1.0(5) 89.2 ± 1.4(5) 88.2 ± 0.8(4)1 74.4 ± 9.6(4) 23.3 ± 12.6(4).sup.b 8.5 ± 6.9(3).sup.b 33.6 ± 16.6(5).sup.b2 0.0 ± 0.0(4) 0.0 ± 0.0(3).sup. 0.0 ± 0.0(3) 0.0 ± 0.0(4).sup.b3 22.8 ± 6.6(4).sup.b 0.0 ± 0.0(4).sup.b 0.0 ± 0.0(3).sup.b 0.0 ± 0.0(3).sup.b4 0.0 ± 0.0(3).sup.b 0.0 ± 0.0(4).sup.b 0.0 ± 0.0(3) 0.0 ± 0.0(3).sup.b5 25.9 ± 0.7(3).sup.b 0.0 ± 0.0(3).sup.b 0.0 ± 0.0(3).sup.b 7.0 ± 1.1(3).sup.b6 54.3 ± 1.3(3).sup.b 0.0 ± 0.0(3).sup.b 0.0 ± 0.0(3).sup.b 42.2 ± 1.3(3).sup.b7 17.4 ± 7.9(3).sup.b 0.0 ± 0.0(4).sup.b 0.0 ± 0.0(4).sup.b 0.0 ± 0.0(4).sup.b8 0.0 ± 0.0(4).sup.b 0.0 ± 0.0(4).sup.b 0.0 ± 0.0(4).sup.b 0.0 ± 0.0(4).sup.b9 0.0 ± 0.0(3).sup.b 0.0 ± 0.0(4).sup.b 0.0 ± 0.0(4).sup.b 0.0 ± 0.0(3).sup.b10 0.0 ± 0.0(3).sup.b 0.0 ± 0.0(4).sup.b 0.0 ± 0.0(4).sup.b 0.0 ± 0.0(3).sup.b11 0.0 ± 0.0(4).sup.b 0.0 ± 0.0(4).sup.b 0.0 ± 0.0(4).sup.b 0.0 ± 0.0(4).sup.b12 0.0 ± 0.0(3).sup.b 0.0 ± 0.0(3).sup.b 0.0 ± 0.0(3).sup.b 0.0 ± 0.0(3).sup.b__________________________________________________________________________ .sup.a Platelets were preincubated with DMSO (0.5%, control) or (methylene-butyrolactones (100 μg/ml) at 37° for 3 min, and the inducer was then added. Percentages of aggregation are presented as means ± standard errors of the mean (n). .sup.b Significantly different from control value at p < 0.001. TABLE 2______________________________________IC.sub.50 values of α-methylene-γ-butyrolactones on theplatelet aggregation induced by Thr (0.1 U/ml),AA (100 μg/ml), Col (10 μg/ml), and PAF (2 nM) IC.sub.50 (μg/ml)Compds Thr AA Col PAF______________________________________1 >50 >50 >50 >502 ND.sup.a 2.86 ND 36.013 >50 26.08 ND >504 ND 1.27 ND 5.705 ND 10.53 ND ND6 >50 8.30 ND >507 >50 23.91 27.25 47.868 15.78 4.70 4.76 11.139 13.69 6.31 5.17 12.3710 >50 17.51 16.24 39.5611 14.88 4.44 5.76 10.5412 ND 4.19 ND 10.82______________________________________ .sup.a Not Determined

The present inventors have discovered three classes of novel α-methylene-γ-butyrolactones with excellent antiplatelet activity. As a result of intensive studies, it has been found that compounds represented by the formula I-III are potent inhibitors of platelet aggregation. ##STR1## For the formula I, R 1 is a methyl, a phenyl group optionally substituted with one or two group selected from halide, (C 1 -C 4 ) alkyl, (C 1 -C 4 ) alkoxy, phenyl, nitro, amino. For the formula II, R 1 is a methyl, a phenyl group optionally substituted with one or two group selected from halide, (C 1 -C 4 ) alkyl, (C 1 -C 4 ) alkoxy, phenyl, nitro, amino; R 2 represents hydrogen, halide, (C 1 -C 4 ) alkyl, phenyl, nitro, amino; R 3 represents hydrogen, halide, (C 1 -C 4 ) alkyl, phenyl, nitro, amino. For the formula III, R 1 is a methyl, a phenyl group optionally substituted with one or two group selected from halide, (C 1 -C 4 ) alkyl, (C 1 -C 4 ) alkoxy, phenyl, nitro, amino; R 4 represents hydrogen, hydroxy, (C 1 -C 4 ) alkyl. The present invention also provides a cost-efficient method for the preparation of formula I-III. Formula I-III may be administered orally or parenterly with an inert diluent or with a pharmaceutically acceptable carrier in the treatment or the prevention of cardiovascular disease.

CROSS-REFERENCE TO RELATED APPLICATION This is related to, and claims a benefit of priority from, U.S. Provisional Patent Application Ser. No. 60/354,618, which was filed on Feb. 6, 2002. FIELD OF THE INVENTION The present invention relates to lights, light fixtures, and other lighting apparatus for residential and commercial use. BACKGROUND OF THE INVENTION In the field of residential and commercial lighting, a variety of applications generate light from point sources. Whether a lighting application utilizes charged gas particles, such as a neon tube, or a current resisting filament, such as an ordinary household light bulb, the intensity of the light generated at the point source can be significant. In many instances, the light intensity is great enough to cause discomfort or harm to any person viewing the light at its point source. As a result, numerous constructions have been utilized to shield viewers from the intense light emanating from the point where the light is generated. At the same time, these designs have been intended to facilitate the diffusion of as much of the generated light as possible in order to maintain an efficient lighting application. The result is that these lighting applications balance the requirement to shield viewers from the intense light at its point source with the requirement to use as much of the generated light as possible, but in a diffused form. This balance of requirements has been accomplished in various ways. For example, ordinary household light bulbs are often frosted in order to reduce the intensity of light at the point source while diffusing as much of the generated light as possible. In addition, frosted and textured globes serve a similar purpose. In related applications, light sources are often shaded, which primarily serves to block the intense light at its point source from the viewer while at the same time redirecting useable light to reflective surfaces such as walls and ceilings. Another solution utilized to block light from the viewer is a recessed lighting application, which removes the light source from the common view, in order to reduce the chance that a viewer will encounter intense light at the point source. While all of these conventional arrangements are intended to provide diffused light with minimal light loss, it remains that a significant amount of light must be blocked in order to reduce the chance that a viewer will encounter intense light at its point source. In providing a solution to these competing requirements, torchiere-type lights have been utilized to provide light that is nearly entirely reflected off nearby walls and ceilings. The light source is positioned in an opaque bowl at the top end of a pedestal so that a viewer has virtually no opportunity of encountering the intense light at its point source. At the same time, the light source is positioned within the bowl so that much of the generated light is directly projected toward the nearby walls and ceilings. The remaining generated light is reflected from the interior of the bowl toward the same nearby walls and ceilings, thereby minimizing the amount of light that is lost. Thus, the torchiere uses a single, large, high-efficiency light source, an improvement over the small, multiple bulbs used by conventional lamps. The torchiere also provides a more uniform light distribution, and allows for variable beam control. However, there are disadvantages to torchiere-type lights as well. In particular, the pedestal usually must be tall, which makes the lamp inherently unstable; the intensity and heat produced by the luminaire is usually greater than that of an ordinary household light bulb, thereby posing a greater fire risk; and the wiring used by a torchiere-type light is similar to that used in ordinary table and floor lamps, which can contribute to common household accidents. Thus, while existing lighting applications have increased the amount of useable light and improved shielding, inherent disadvantages continue to exist. The noted deficiencies should be overcome in order to maximize the amount of useable light, maintain shielding, and otherwise improve existing lighting applications. The resulting lighting effect should also be more pleasing and efficient than that provided by a direct lighting source. SUMMARY OF THE INVENTION The present invention provides many of the advantages of the torchiere-type light while at the same time improving upon the inherent disadvantages of that lighting application. In particular, the light source for the present invention is contained in a housing that is recessed in a ceiling or other structure and directed toward a pendant reflector similar to the reflective bowl provided behind the lighting element in torchiere-type lights. This provides a construction for reflecting and diffusing light. Page: 3 The resulting construction results in a reduction in the amount of glare present at the light source, allows for the utilization of glass and heat-sensitive materials that cannot otherwise be used in ceiling lighting fixtures, as well as the use of the latest lamp technologies, such as fluorescent, HID, LED, and halogen light sources. In contrast to conventional pendant fixtures, the present invention provides a recessed light source with a non-electrical suspension and reflector. Preferred embodiments of the present invention use a single, efficient focused beam lamp, rather than multiple small flood lamps. The design makes use of a hidden recessed housing for the larger lamp, as well as novel recessed housings, and allows for single lamp replacement maintenance. The passive reflector of the present invention, which does away with visible lamp and electrical hardware, provides a more pleasing, shallow profile, allows use of heat sensitive materials, with reduced fire hazard, and enables the use of less opaque, more transparent materials. Particular embodiments include a slender suspension, provided by a continuous loop to provide simpler height (drop), slope, and leveling adjustments. The suspension can be effectuated by variable lacing configurations, or fixed length chain or spoke suspension materials. Additionally, the present invention incorporates specific ceiling structures, not present in conventional lights, such as pendant fixtures, that are designed to enhance the diffusion of the generated light. Also, because the light source is not incorporated as part of the pendant reflector, the attendant fixture and lighting elements do not obstruct movement within a room, as conventional floor lamps can. Further, the absence of such elements allows more flexibility in the choice of materials for the pendant reflector itself, due to the reduced proximity of the light source to the reflector. An embodiment of the present invention includes a light source contained within a housing recessed within a ceiling. Illumination from the light shines downward in a substantially vertical orientation and reflects off a concave reflector suspended from the ceiling and positioned directly in the path of the light. The result is that the generated light is both shielded by the pendant reflector and diffused by being reflected onto the walls and ceiling. The suspension apparatus for the pendant reflector includes a continuous loop of flexible cord or ire that is threaded between the ceiling and the reflector. This allows the orientation of the pendant reflector to be adjusted easily without special tools. In addition, the present invention can be outfitted with a reflector dome or reflector cove positioned around the light source and opposite the reflective surface of the pendant reflector. These aspects serve to redirect the diffused light reflected by the pendant reflector while shielding a viewer from the intense light present at its point source. According to one aspect of the present invention, a lighting assembly includes a light socket, a first reflector base, and a second reflector base. The light socket is at least partially disposed in a housing. The first reflector base has an aperture through which the light socket is accessible, and a reflective surface generally facing away from the light socket. The second reflector base is connected to the first reflector base, the light source housing, or both, and has a reflective surface generally facing the light source and the reflective surface of the first reflector base. The first reflection base can have a flat reflective surface adjacent the aperture, and a curved reflective surface at the periphery of the first reflection base, wherein the curved reflective surface curves generally toward the second reflector base. Alternatively, the reflective surface of the first reflector base can be concave altogether, wherein the concavity is directed generally toward the second reflector base. Likewise, the reflective surface of the second reflector base can be concave, wherein the concavity is directed generally toward the first reflector base. In preferred embodiments of the present invention, the area of the reflective surface of the first reflector base is larger than the area of the reflective surface of the second reflector base. The basic structure of the lighting assembly of the present invention can be adapted advantageously to many different installations. For example, the light socket housing can be recessed within a ceiling, with the light socket facing downward from the ceiling. In this case, the first reflector base can be disposed on the surface of the ceiling, with the reflective surface of the first reflector base facing generally downward from the ceiling, and the second reflector base can be a pendant suspended from any of the first reflector base, the light source housing, and the ceiling, with the reflective surface of the second reflector base facing generally upward toward the ceiling. In this embodiment, the light socket housing can include a suspension lacing ring, and the lighting assembly can further include suspension lacing connected to the suspension lacing ring and the second reflector base. Alternatively, the first reflector base can be recessed within the surface of the ceiling, with the reflective surface of the first reflector base facing generally downward from the ceiling. In this case, the second reflector base can be a pendant suspended from any of the first reflector base, the light source housing, and the ceiling, with the reflective surface of the second reflector base facing generally upward toward the ceiling. In this embodiment, the light socket housing can includes a suspension lacing ring, and the lighting assembly can further include suspension lacing connected to the suspension lacing ring and the second reflector base. In an alternative embodiment, the lighting assembly of the present invention can be used in an arena environment, such that the light socket housing is suspended from a ceiling structure, with the light socket facing downward from the ceiling structure. In this case, the first reflector base is also suspended from the ceiling structure, with the reflective surface of the first reflector base facing generally downward from the ceiling structure. Either or both of the light socket housing and the first reflector base can be suspended from the ceiling directly, or indirectly through the other component. As in the previously-described embodiments, the second reflector base can be a pendant suspended from any of the first reflector base, the light source housing, and the ceiling structure, with the reflective surface of the second reflector base facing generally upward toward the ceiling structure. In this case, the light socket housing can include a suspension lacing ring, and the lighting assembly can further include suspension lacing connected to the suspension lacing ring and the second reflector base. According to another embodiment of the present invention, the first reflector base can be recessed within a desktop, with the reflective surface of the first reflector base facing generally upward from the desktop. In this embodiment, the second reflector base can be held above the first reflector base by spacers connected to at least one of the first reflector base, the light source housing, and the desktop, with the reflective surface of the second reflector base facing generally downward toward the first reflector base. According to still another embodiment of the present invention, the first reflector base can be mounted atop a stand, such as a lamp stand with the reflective surface of the first reflector base facing generally upward from the stand. In this embodiment, the second reflector base can be held above the first reflector base by spacers connected to at least one of the first reflector base, the light source housing, and the stand, with the reflective surface of the second reflector base facing generally downward toward the first reflector base. In any of these embodiments, the light socket can be of the type that is adapted to secure and provide electrical power to a light source, such as an incandescent light bulb, a halogen light bulb, a compact fluorescent bulb, an HID, and an LED. Further, to effectuated a desired lighting effect, the shape of the first reflector base, the second reflector base, or their respective reflective surfaces can be any shape, such as round, elliptical, ovular, or irregular. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an elevation view of the light fixture, including the recessed light source, pendant reflector, suspension lacing, and reflection cove. FIG. 2 shows an elevation view of the light fixture, including the recessed luminaire housing, pendant reflector, suspension lacing, and reflection dome. FIG. 3 shows a detailed exploded perspective view of the recessed luminaire housing, suspension lacing ring, and aperture plate. FIG. 4 shows a perspective view of the suspension lacing ring, suspension lacing, and pendant reflector. FIG. 5 shows a perspective view of the suspension lacing using three eyelets each at the suspension lacing ring and at the pendant reflector, with pendant reflector cut-away detail. FIG. 6 shows a perspective view of the suspension lacing using four eyelets each at the suspension lacing ring and at the pendant reflector, with pendant reflector cut-away detail. FIG. 7 shows a perspective view of the suspension lacing using five eyelets each at the suspension lacing ring and at the pendant reflector, with pendant reflector cut-away detail. DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 1 , a lighting apparatus 30 according to the present invention includes a luminaire 1 that is contained within a luminaire housing 2 . The luminaire housing 2 is fitted to a ceiling 31 such that it is recessed within the ceiling 31 . The luminaire housing 2 is attached to the ceiling 31 using common construction techniques, and power is provided to the luminaire 1 by conventional means, such as a direct connection by wiring 43 to a junction box 32 or other power source. A standard-type light socket 3 is fitted to the interior base of the luminaire housing 2 such that the bulb 4 portion of the luminaire 1 is directed toward the open end 33 of the luminaire housing 2 , that is, downward from the ceiling 31 . It is contemplated that the luminaire housing 2 of the present invention can accommodate any type of residential or commercial light socket or connection, such as a receptacle for a halogen bulb or compact fluorescent lamp, or wires and clips for two-terminal style suspended lighting elements. The base of the luminaire 1 is in communication with the light socket 3 and is secured by a conventional means, such as by screwing or snapping the light socket 3 into the base of the luminaire 1 , and by providing appropriate electrical communication between the wiring 43 and the light socket 3 by, for example, solder joint or crimping connection. The luminaire housing 2 can be positioned in any type of ceiling, including a joist-type ceiling or a suspended ceiling, using common construction techniques. Also, it can be positioned in an arena environment, suspended from the roof where it appears to be recessed in an imaginary ceiling. In the exemplary embodiment shown in FIG. 1 , the edge of the open end 33 of the luminaire housing 2 is approximately flush with the surrounding surface. It is contemplated that in other embodiments, the luminaire housing 2 can extend from the ceiling, either by attachment to the ceiling at the closed end 34 of the luminaire housing 2 , or by cabling or other hanging attachments in an arena, warehouse, or other environment having an open ceiling. In certain embodiments, a portion of the side of the luminaire housing 2 proximate to the open end 33 of the luminaire housing 2 can be joined to the vertically situated mating surface of the recess existing in the interior ceiling 31 of a room. Likewise, a portion of the side of the luminaire housing 2 proximate to the open end 33 of the luminaire housing 2 can be joined to the vertically situated mating surface of the light fixture access hole existing in either a reflection cove 6 ( FIG. 1 ) or a reflection dome 7 (FIG. 2 ), again using standard construction techniques. With reference to FIG. 3 , in an exemplary embodiment, the upper horizontal surface 10 of a suspension lacing ring 9 is in communication with the open end 33 edge surface of the luminaire housing 2 . In an exemplary embodiment, the upper horizontal surface 10 of a suspension lacing ring 9 is joined to the open edge surface of the luminaire housing 2 , using known construction techniques, such as through the use of commercially available construction adhesive (such as glue, joint compound, or epoxy), friction fit mating surfaces, spot welding, or fasteners. In another exemplary embodiment, the open space of the suspension lacing ring 9 has a larger diameter than that of the luminaire housing 2 . In this embodiment, there is no communication between the suspension lacing ring 9 and the luminaire housing 2 . Instead, the upper horizontal surface 10 of the suspension lacing ring 9 is in sole communication with the lower surface of the reflection cove 6 , the lower surface of the reflection dome 7 , or the surface of the ceiling 31 , depending on the application selected. As shown in FIG. 3 , in one exemplary embodiment, the suspension lacing ring 9 is removably attached to the luminaire housing 2 by an aperture plate 35 , which includes a lower annular ridge 36 to support the suspension lacing ring 9 , and can be snap-fit or otherwise attached to the luminaire housing 2 by, for example, flanges 37 . The aperture plate 35 includes an aperture through which light from the luminaire 1 can pass. The suspension lacing ring 9 can be attached to the ceiling by a set of screws 38 or other fasteners, which can be affixed to a stem 31 connecting the wirebox of the recessed housing to the associated lamp housing in the ceiling through, for example, the suspension lacing ring 9 . The lower horizontal surface 11 of the suspension lacing ring 9 is fitted with a series of suspension eyelets 12 , hooks, or other open guide construction, secured to the suspension lacing ring 9 . In an exemplary embodiment, the suspension lacing ring 9 is made of molded plastic or metal, in which the suspension eyelets 12 are integrated as part of the suspension lacing ring mold. In other embodiments, the suspension eyelets 12 are distinct pieces of hardware secured to the lower horizontal surface 11 of the suspension lacing ring 9 using threads, friction, adhesion, or welding. The suspension eyelets 12 are utilized to secure suspension lacing 13 , which in turn holds a pendant reflector 15 suspended below the luminaire housing 2 , as shown in FIG. 4 . This pendant reflector 15 has an upper concave surface generally opposite the suspension lacing ring 9 . Likewise, the upper concave surface 14 of the pendant reflector 15 is fitted with a series of pendant eyelets 16 , hooks, or other open guide construction, secured to the pendant reflector 15 . In an exemplary embodiment, the pendant reflector 15 is made of molded plastic or metal, in which the pendant eyelets 16 are integrated as part of the pendant reflector mold. In other exemplary embodiments, the pendant reflector 15 is fabricated of plastic, metal, or glass, and the pendant eyelets 16 are distinct pieces of hardware secured to the upper concave surface 14 of the pendant reflector 15 using, for example, threads, friction, adhesion, or welding. The number of suspension eyelets 12 utilized by the apparatus of the present invention is a consideration based on the ornamental design of the lighting apparatus 30 , as well as on structural factors such as the dimensions and weight of the pendant reflector 15 . For example, in an exemplary embodiment shown in FIG. 5 , three suspension eyelets 12 are fitted to the lower horizontal surface 11 of the suspension lacing ring 9 . In another exemplary embodiment, as shown in FIG. 6 , four suspension eyelets 12 are fitted to the lower horizontal surface 11 of the suspension lacing ring 9 . In yet another exemplary embodiment, as shown in FIG. 7 , five suspension eyelets 12 are fitted to the lower horizontal surface 11 of the suspension lacing ring 9 . Regardless of the number of eyelets fitted to the lower horizontal surface 11 of the suspension lacing ring 9 , each suspension eyelet 12 is positioned so as to provide the desired look and structural integrity. For example, the suspension eyelets 12 can be disposed at equal distances from each adjacent suspension eyelet 12 , in a regular but non-equidistant arrangement, or in an asymmetrical pattern. Each suspension eyelet 12 has an open space, or other opening that allows the suspension lacing 13 to be threaded through each suspension eyelet 12 , or through any number of provided suspension eyelets 12 that are desired. Preferably, the open space of each suspension eyelet 12 is formed to allow the suspension lacing 13 to pass freely through the open space of each suspension eyelet 12 without snagging, although a grasping or fixing construction can be utilized in order to hold the suspension lacing 13 in place. Likewise, the number of pendant eyelets 16 utilized by the present invention is a consideration based on the ornamental design of the light, as well as on structural factors such as the dimensions and weight of the pendant reflector 15 . For example, in an exemplary embodiment shown in FIG. 5 , three pendant eyelets 16 are fitted to the upper concave surface 14 of the pendant reflector 15 . In another exemplary embodiment, as shown in FIG. 6 , four pendant eyelets 16 are fitted to the upper concave surface 14 of the pendant reflector 15 . In yet another exemplary embodiment, as shown in FIG. 7 , five pendant eyelets 16 are fitted to the upper concave surface 14 of the pendant reflector 15 . Regardless of the number of pendant eyelets 16 fitted to the upper concave surface 14 of the pendant reflector 15 , the pendant eyelets 16 are arranged so as to provide the desired look and structural integrity, such as at equal distances from each adjacent pendant eyelet 16 , in, for example, a circular pattern, in a regular but non-equidistant arrangement, or in an asymmetrical pattern. In any embodiment, the number of pendant eyelets 16 fitted to the upper concave surface 14 of the pendant reflector 15 can be equal to the number of suspension eyelets 12 fitted to the lower horizontal surface 11 of the suspension lacing ring 9 . Alternatively, the number of suspension eyelets 12 can be different than the number of pendant eyelets 16 , in order to provide flexibility in arranging the pendant reflector 15 . Each pendant eyelet 16 has an open space or other opening, which allows the suspension lacing 13 to be threaded through each pendant eyelet 16 , or through any number of provided pendant eyelets 16 that are desired. Preferably, the open space of each pendant eyelet 16 is manufactured to allow the suspension lacing 13 to pass freely through the open space of each pendant eyelet 16 without snagging, although a grasping or fixing construction can be utilized in order to hold the suspension lacing 13 in place. In alternative embodiments, some or all of the suspension eyelets 12 can be attached to the ceiling 31 , or to a reflection cove 6 (described below) or reflection dome 7 (also described below). These embodiments provide alternative or additional support for the pendant reflector 15 , alternative ornamentation for the lighting apparatus 30 , and potential differences in effect on the resulting diffused light. The pendant reflector 15 is fabricated in the shape of a concave bowl 17 , such that the concave surface is directed at least generally toward the light source, so as to be able to reflect a least a portion of the light directed toward the pendant reflector 15 by the light source. The shape of the periphery of the concave bowl 17 , as well as the degree of concavity, is determined by the light-diffusing qualities desired for the assembly. For example, according to an exemplary embodiment, the shape of the concave bowl 17 can be spherical, and the degree of concavity of the concave bowl 17 can be defined in all directions about its center point by the arc of a circle having a predetermined diameter, such as ten feet, or twenty feet, or any desired dimension, preferably having a diameter of between about 18 inches and about 96 inches. Alternatively, the peripheral shape of the concave bowl 17 can be elliptical, or any other desired shape, and the pendant reflector 15 itself can be flat, or convex. The pendant reflector 15 can be fabricated from any of a variety of materials, including production glass, limited edition art glass, spun metal, marquetry or other arrangement of wood, leather, fabric appliqué on a sturdy foundation, porcelain, or plastic. In addition, painted finishes can be applied to the pendant reflector 15 , both on the outside to provide a desired ornamental look, and on the inside, to provide desired reflective features. The suspension lacing 13 is fabricated from any of a variety of materials, including metal cable, cord, or monofilament, as well as various textile, synthetic, or composite materials. Although the suspension lacing 13 can be composed of several discrete lengths of material, it preferably is constructed as a continuous loop and threaded in a variety of ways through the suspension eyelets 12 and the pendant eyelets 16 . In an exemplary embodiment, as shown in FIG. 5 , the suspension lacing 13 is threaded sequentially through the suspension eyelets 12 and the pendant eyelets 16 at positions POS 1 , POS 4 , POS 2 , POS 5 , POS 3 , and POS 6 . In another exemplary embodiment, as shown in FIG. 6 , the suspension lacing 13 is threaded sequentially through the suspension eyelets 12 and the pendant eyelets 16 at positions POS 1 , POS 5 , POS 2 , POS 6 , POS 3 , POS 7 , POS 4 , and POS 8 . In yet another exemplary embodiment, as shown in FIG. 7 , the suspension lacing 13 is threaded sequentially through the suspension eyelets 12 and the pendant eyelets 16 at positions POS 1 , POS 6 , POS 2 , POS 7 , POS 3 , POS 8 , POS 4 , POS 9 , POS 5 , and POS 10 . It is contemplated that any quantity and arrangement of the suspension eyelets 12 and the pendant eyelets 16 can be used, including embodiments in which the number of suspension eyelets 12 is different than the number of pendant eyelets 16 , in which the suspension lacing 13 is threaded more than once through one or more of the suspension eyelets 12 or the pendant eyelets 16 , and in which some of the suspension eyelets 12 or the pendant eyelets 16 do not have the suspension lacing 13 threaded through them at all. The length of the suspension lacing 13 is also variable, depending on the number of threaded eyelets, the desired arrangement of the suspension lacing 13 , and the distance required between the lower horizontal surface 11 of the suspension lacing ring 9 and the pendant reflector 15 for proper reflection and diffusion of light. For example, for the embodiment shown in FIG. 5 , if the overall length of the suspension lacing 13 is between approximately five feet and eight feet, the vertical distance between the suspension lacing ring 9 and the pendant reflector 15 would be between approximately ten inches and 16 inches. For the embodiment shown in FIG. 6 , if the overall length of the suspension lacing 13 is between approximately seven feet and 11 feet, the vertical distance between the suspension lacing ring 9 and the pendant reflector 15 would be between approximately 11 inches and 16 inches. For the embodiment shown in FIG. 7 , if the overall length of the suspension lacing 13 is between approximately nine feet and 13 feet, the vertical distance between the suspension lacing ring 9 and the pendant reflector 15 would be between approximately 11 inches and 16 inches. In each exemplary embodiment, and in those not shown, the distance between the suspension lacing ring 9 and the pendant reflector 15 can be adjusted by shortening the suspension lacing 13 , or by replacing the suspension lacing 13 with a longer piece. It is contemplated that the present invention can be embodied such that the suspension lacing 13 is not formed as a continuous loop, but rather as a length of material that can be threaded between fixed points to an extent that provides the desired distance between the suspension lacing ring 9 and the pendant reflector 15 . In addition, while the suspension lacing 13 is threaded between the suspension eyelets 12 and the pendant eyelets 16 , the orientation of the pendent reflector 15 can be changed by lifting the pendent reflector 15 and adjusting the suspension lacing 13 . In this manner, the release and application of tension on the suspension lacing 13 by hand makes it possible to orient the top plane of the pendant reflector 15 in an substantially horizontal position. If a grasping or otherwise prehensile construction is used for the suspension eyelets 12 or the pendant eyelets 16 , the pendant reflector 15 can be adjusted such that it is not oriented in a substantially horizontal position, or can be adjusted to adapt to a sloped ceiling such that the pendant reflector 15 is oriented in a substantially horizontal position. Alternatively, the suspension lacing 13 can be replaced with rigid rods, spokes, or chains, or other suitable spacers attached to the pendant reflector 15 and any combination of the upper support structures. In other exemplary embodiments, the upper horizontal surface 10 of the suspension lacing ring 9 is in communication with the lower surface of a reflection cove 6 , as shown in FIG. 1 . As shown, the reflection cove 6 is positioned toward the front end of the luminaire housing 2 , and includes an aperture 39 through which light from within the luminaire housing 2 can pass. The suspension lacing ring 9 is preferably disposed so that the open space of the suspension lacing ring 9 and the aperture 39 of the reflection cove 6 are positioned to allow the maximum amount of light to pass from the luminaire housing 2 to the pendent reflector 15 without obstruction. The upper horizontal surface 10 of the suspension lacing ring 9 is joined to the lower surface of the reflection cove 6 by conventional construction techniques, such as through the use of a construction glue, joint compound, epoxy, or other common adhesive, or with fasteners, such as nails, tacks, screws, or rivets. The reflection cove 6 is fabricated such that the lower surface of the reflection cove 6 is curved in the shape of a concave bowl 18 , with the concavity directed generally toward the pendant reflector 15 . The lower surface can have any curved shape, such as spherical, elliptical, or tubular section, dictated by the geometry of the rest of the light apparatus, and by the desired diffusion pattern of the resultant light. Alternative embodiments of the reflection cove 6 can also have surfaces that arc flat, or convex. The lower surface of the reflection cove 6 of the exemplary embodiment shown in FIG. 1 is defined by the arc of a circle. Similar embodiments can have different degrees of curvature, depending on the desired reflection pattern. For example, a reflection cove 6 shaped as a spherical section can have a degree of curvature defined by a sphere having a of any appropriate dimension, such as a diameter in a range of between four feet to about 12 feet. The reflection cove 6 can bc fabricated from any of a variety of materials, including production glass, limited edition art glass, spun metal, marquetry or other wood surfaces, leather, fabric appliqué on a sturdy material base, porcelain, plastic, or a casting of fiber reinforced plaster composite. In addition, painted finishes can be applied to the reflection cove 6 , either for ornamental effect or reflective quality. In an exemplary embodiment, the base 19 of the reflection cove 6 is affixed to the surface of an interior ceiling by conventional construction techniques, such as through the use of a construction glue, joint compound, epoxy, or other common adhesive, or with fasteners, such as nails, tacks, screws, or rivets. The edge of the aperture 39 of the reflection cove 6 is in communication with a portion of the side of the luminaire housing 2 proximate to the open end of the luminaire housing 2 . In an exemplary embodiment, the edge of the aperture of the reflection cove 6 is joined with a portion of the side of the luminaire housing 2 proximate to the open end of the recessed luminaire housing 2 . In an exemplary embodiment, the lower peripheral edge 40 of the reflection cove 6 is circular in shape, with a diameter that is suitable for the overall geometry of the apparatus, for example, between 36 inches and 72 inches, with a thickness of 4″ to 12″ for flat backed coves. Also in an exemplary embodiment, the base periphery 41 of the reflection cove 6 is circular in shape, with a diameter that is suitable for the overall geometry of the apparatus, for example, between about two feet and about six feet. In other exemplary embodiments, the lower peripheral edge 40 and base periphery 41 of the reflection cove 6 are not circular. Either or both can be some other rounded, polygonal, or mixed shape. In another exemplary embodiment, the upper horizontal surface 10 of the suspension lacing ring 9 is in communication with the lower surface of a reflection dome 7 , as shown in FIG. 2 . As shown, the reflection dome 7 is recessed in the ceiling, and is positioned toward the front end of the luminaire housing 2 , and includes an aperture 42 through which light from within the luminaire housing 2 can pass. The suspension lacing ring 9 is preferably disposed so that the open space of the suspension lacing ring 9 and 20 the aperture 42 of the reflection dome 7 are positioned to allow the maximum amount of light to pass from the luminaire housing 2 to the pendent reflector 15 without obstruction. The upper horizontal surface 10 of the suspension lacing ring 9 is joined to the lower surface of the reflection dome 7 by conventional construction techniques, such as through the use of a construction glue, joint compound, epoxy, or other adhesive, or with fasteners such as nails, tacks, screws, or rivets. The reflection dome 7 is fabricated such that the lower surface of the reflection dome 7 is formed in the shape of a concave bowl 20 , with the concavity directed generally toward the pendant reflector 15 . The lower surface can have any curved shape, such as spherical, elliptical, or tubular section, dictated by the geometry of the rest of the light apparatus, and by the desired diffusion pattern of the resultant light. Alternative embodiments of the reflection dome 7 can also have surfaces that are flat, or convex. The lower surface of the reflection dome 7 of the exemplary embodiment shown in FIG. 2 is defined by the arc of a circle. Similar embodiments can have different degrees of curvature, depending on the desired reflection pattern. For example, a reflection dome 7 shaped as a spherical section can have a degree of curvature defined by a sphere having a diameter of between about two and six feet, or any appropriate dimension. The reflection dome 7 can be fabricated from any of a variety of materials, including production glass, limited edition art glass, spun metal, marquetry or other wood surfaces, leather, fabric appliqué on a sturdy material base, porcelain, or plastic. In addition, painted finishes can be applied to the reflection dome 7 , either for ornamental effect or reflective quality. In the exemplary embodiment shown in FIG. 2 , the reflection dome 7 is recessed entirely within an opening in the surface of an interior ceiling. The reflection dome 7 is secured to ceiling support structures in a manner consistent with standard home construction techniques. The edge of the upper aperture of the reflection dome 7 is in communication with a portion of the side of the luminaire housing 2 proximate to the open end of the luminaire housing 2 . In an exemplary embodiment, the edge of the upper aperture of the reflection dome 7 is joined with a portion of the side of the luminaire housing 2 proximate to the open end of the luminaire housing 2 . In an exemplary embodiment, the outer peripheral edge of the reflection dome 7 is circular in shape, with a diameter that is suitable for the overall geometry of the apparatus, for example, between one and two feet. In other exemplary embodiments, the outer peripheral edge of the reflection dome 6 are not circular, and can be some other rounded, polygonal, or mixed shape. Preferred and alternative embodiments of the present invention have been described in detail. The particular described embodiments are not limiting of the present invention. Rather, the described embodiments are illustrative of the inventive concept, which is recited in the claims. The claims, therefore, should be given the broadest interpretation possible, limited only by the known prior art, and not by any exemplary structural details set forth in the written description. Various structural details of the present invention as described may be modified within the spirit and scope of the present invention as contemplated by the inventor. For example, the lighting apparatus of the present invention need not be suspended from a ceiling, and instead can be embodied as a floor lamp, desk lamp, or recessed lamp within a desktop (stated broadly to include a counter top or table top). For example, FIG. 8 shows the lighting apparatus of the present invention in an exemplary floor lamp 50 embodiment. The floor lamp 50 includes a weighted base 51 , a stand 52 , and a light source 59 , such as a luminaire within a housing 53 . The luminaire housing 53 is supported by the stand 52 , which may be a rigid rod or somewhat flexible (bendable) support that allows the light source 59 to be directed to a certain degree. The weighted base 51 has a proper combination of footprint surface area and mass to ensure that the floor lamp 50 remains upright while the weighted base 51 rests on the floor. The luminaire housing 53 is oriented such that the light emanating from the light source 59 is aimed in a generally upward direction. A primary reflector 54 is positioned generally opposite the luminaire housing 53 , such that light emanating from the light source 59 is directed generally toward the primary reflector 54 . The primary reflector 54 is made from a material that is sufficiently rigid so as to retain its shape, and that can withstand any heat generated by the light source 59 . The primary reflector 54 has a generally concave shape, oriented such that the concavity is facing the luminaire housing 53 . In an exemplary embodiment, the primary reflector 54 is fabricated from a material that is reflective of light at least to a degree necessary to provide necessary lighting for the desired area proximate to the floor lamp 50 . In another exemplary embodiment, the concave surface of the primary reflector 54 is coated with a material that is reflective of light at least to a degree necessary to provide necessary lighting for the desired area proximate to the floor lamp 50 . The floor lamp 50 also includes a secondary reflector 55 , which is located behind the opening 56 in the luminaire housing 53 , that is, behind the area from which light emanates from the luminaire housing 53 . The secondary reflector 55 has a generally concave shape, oriented such that the concavity is facing the primary reflector 54 . In an exemplary embodiment, the secondary reflector 55 is fabricated from a material that is reflective of light at least to a degree necessary to provide necessary lighting for the desired area proximate to the floor lamp 50 . In another exemplary embodiment, the concave surface of the secondary reflector 55 is coated with a material that is reflective of light at least to a degree necessary to provide necessary lighting for the desired area proximate to the floor lamp 50 . The secondary reflector 55 has an aperture 57 through which the opening 56 of the luminaire housing 53 is directed, and by which the secondary reflector 55 is attached to the luminaire housing 53 . Light emanating from the luminaire housing 53 passes through the aperture 57 , so that it can reach the primary reflector 54 with little or no obstruction. The primary reflector 54 is connected to the luminaire housing 53 or the secondary reflector 55 , or both, by extension rods 58 or other suitable spacers. The extension rods 58 are sufficiently rigid to hold the primary reflector 54 in place, but do not substantially block light reflected from the primary reflector 54 or the secondary reflector 55 . Thus, the light emanating from the light source 59 within the luminaire housing 53 reflects off the primary reflector 54 , the reflected light reflects off the secondary reflector 55 , and the twice-reflected light illuminates the space in which the floor lamp 50 is located. Some percentage of the initial light from the light source 59 may directly illuminate the room by passing unreflected past the primary reflector 54 , depending on the degree of focus of the light source 59 and the size of the primary reflector 54 . Likewise, some percentage of the light reflected from the primary reflector 54 may directly illuminate the room by passing unreflected past the secondary reflector 55 , depending on the degree of diffusion of the reflected light and the size of the secondary reflector 55 . The number and arrangement of the extension rods 58 are determined by the material and dimensions of the extension rods 58 , as these parameters affect the structural integrity of the floor lamp 50 , the desired ornamental look of the floor lamp 50 , and the desired partial blocking effect that the extension rods 58 have on the pattern of the light emanating from the floor lamp 50 . FIG. 9 shows the lighting apparatus of the present invention in an exemplary table or desk lamp 60 embodiment. The table lamp 60 includes a weighted base 61 , a stand 62 , and a light source 69 , such as a luminaire within a housing 63 . The luminaire housing 63 is supported by the stand 62 , which may be a rigid rod or somewhat flexible (bendable) support that allows the light source 69 to be directed to a certain degree. The weighted base 61 has a proper combination of footprint surface area and mass to ensure that the table lamp 60 remains upright while the weighted base 61 rests on the table. The luminaire housing 63 is oriented such that the light emanating from the light source 69 is aimed in a generally upward direction. A primary reflector 64 is positioned generally opposite the luminaire housing 63 , such that light emanating from the light source 69 is directed generally toward the primary reflector 64 . The primary reflector 64 is made from a material that is sufficiently rigid so as to retain its shape, and that can withstand any heat generated by the light source 69 . The primary reflector 64 has a generally concave shape, oriented such that the concavity is facing the luminaire housing 63 . In an exemplary embodiment, the primary reflector 64 is fabricated from a material that is reflective of light at least to a degree necessary to provide necessary lighting for the desired area proximate to the table lamp 60 . In another exemplary embodiment, the concave surface of the primary reflector 64 is coated with a material that is reflective of light at least to a degree necessary to provide necessary lighting for the desired area proximate to the table lamp 60 . The table lamp 60 also includes a secondary reflector 65 , which is located behind the opening 66 in the luminaire housing 63 , that is, behind the area from which light emanates from the luminaire housing 63 . The secondary reflector 65 has a generally concave shape, oriented such that the concavity is facing the primary reflector 64 . In an exemplary embodiment, the secondary reflector 65 is fabricated from a material that is reflective, of light at least to a degree necessary to provide necessary lighting for the desired area proximate to the table lamp 60 . In another exemplary embodiment, the concave surface of the secondary reflector 65 is coated with a material that is reflective of light at least to a degree necessary to provide necessary lighting for the desired area proximate to the table lamp 60 . The secondary reflector 65 has an aperture 67 through which the opening 66 of the luminaire housing 63 is directed, and by which the secondary reflector 65 is attached to the luminaire housing 63 . Light emanating from the luminaire housing 63 passes through the aperture 67 , so that it can reach the primary reflector 64 with little or no obstruction. The primary reflector 64 is connected to the luminaire housing 63 or the secondary reflector 65 , or both, by extension rods 68 or other suitable spacers. The extension rods 68 are sufficiently rigid to hold the primary reflector 64 in place, but do not substantially block light reflected from the primary reflector 64 or the secondary reflector 65 . Thus, the light emanating from the light source 69 within the luminaire housing 63 reflects off the primary reflector 64 , the reflected light reflects off the secondary reflector 65 , and the twice-reflected light illuminates the space in which the table lamp 60 is located. Some percentage of the initial light from the light source 69 may directly illuminate the room by passing unreflected past the primary reflector 64 , depending on the degree of focus of the light source 69 and the size of the primary reflector 64 . Likewise, some percentage of the light reflected from the primary reflector 64 may directly illuminate the room by passing unreflected past the secondary reflector 65 , depending on the degree of diffusion of the reflected light and the size of the secondary reflector 65 . The number and arrangement of the extension rods 68 are determined by the material and dimensions of the extension rods 68 , as these parameters affect the structural integrity of the table lamp 60 , the desired ornamental look of the table lamp 60 , and the desired partial blocking effect that the extension rods 68 have on the pattern of the light emanating from the table lamp 60 . FIG. 10 shows the lighting apparatus of the present invention in an exemplary recessed lamp 70 embodiment, located in a recessed space 80 within a counter, desk, or similar piece of furniture 81 . The recessed lamp 70 includes a base 71 supporting a light source 79 , such as a luminaire within a housing 73 . The luminaire housing 73 is oriented such that the light emanating from the light source 79 is aimed in a generally upward direction. A primary reflector 74 is positioned generally opposite the luminaire housing 73 , such that light emanating from the light source 79 is directed generally toward the primary reflector 74 . The primary reflector 74 is made from a material that is sufficiently rigid so as to retain its shape, and that can withstand any heat generated by the light source 79 . The primary reflector 74 has a generally concave shape, oriented such that the concavity is facing the luminaire housing 73 . In an exemplary embodiment, the primary reflector 74 is fabricated from a material that is reflective of light at least to a degree necessary to provide necessary lighting for the desired area proximate to the recessed lamp 70 . In another exemplary embodiment, the concave surface of the primary reflector 74 is coated with a material that is reflective of light at least to a degree necessary to provide necessary lighting for the desired area proximate to the recessed lamp 70 . The recessed lamp 70 also includes a secondary reflector 75 , which is located behind the opening 76 in the luminaire housing 73 , that is, behind the area from which light emanates from the luminaire housing 73 . The secondary reflector 75 has a generally concave shape, oriented such that the concavity is facing the primary reflector 74 . In an exemplary embodiment, the secondary reflector 75 is fabricated from a material that is reflective of light at least to a degree necessary to provide necessary lighting for the desired area proximate to the recessed lamp 70 . In another exemplary embodiment, the concave surface of the secondary reflector 75 is coated with a material that is reflective of light at least to a degree necessary to provide necessary lighting for the desired area proximate to the recessed lamp 70 . The secondary reflector 75 has an aperture 77 through which the opening 76 of the luminaire housing 73 is directed, and by which the secondary reflector 75 is attached to the luminaire housing 73 . Light emanating from the luminaire housing 73 passes through the aperture 77 , so that it can reach the primary reflector 74 with little or no obstruction. Alternatively, the secondary reflector 75 is formed integrally with the base 71 , and the luminaire housing 73 is attached to the secondary reflector 75 at a back side 72 of the luminaire housing 73 . The primary reflector 74 is connected to the luminaire housing 73 , the secondary reflector 75 , the counter/desk 81 , or any combination of the three, by extension rods 78 or other suitable spacers. The extension rods 78 are sufficiently rigid to hold the primary reflector 74 in place, but do not substantially block light reflected from the primary reflector 74 or the secondary reflector 75 . Thus, the light emanating from the light source 79 within the luminaire housing 73 reflects off the primary reflector 74 , the reflected light reflects off the secondary reflector 75 , and the twice-reflected light illuminates the space around which the recessed lamp 70 is located. Some percentage of the initial light from the light source 79 may directly illuminate the room by passing unreflected past the primary reflector 74 , depending on the degree of focus of the light source 79 and the size of the primary reflector 74 . The number and arrangement of the extension rods 78 are determined by the material and dimensions of the extension rods 78 , as these parameters affect the structural integrity of the recessed lamp 70 , the desired ornamental look of the recessed lamp 70 , and the desired partial blocking effect that the extension rods 78 have on the pattern of the light emanating from the recessed lamp 70 .

A lighting assembly includes a light socket, a first reflector base, and a second reflector base. The light socket is at least partially disposed in a housing, and is used to secure and provide electrical power to a light source. The first reflector base has an aperture through which the light socket is accessible, and a reflective surface generally facing away from the light socket, and therefore the light source. The second reflector base is connected to the first reflector base, the light source housing, or both, and has a reflective surface generally facing the light source and the reflective surface of the first reflector base. Light provided by the light source is reflected from the second reflective surface and then the first reflective surface, providing indirect lighting for an observer.

This application is a U.S. National Phase Application of PCT International Application No. PCT/ES2008/000039, filed Jan. 25, 2008. PURPOSE OF THE INVENTION This invention refers to a tightening device the aim of which is to fix a garment, such as trousers, to its user's waist, so as to appropriately stabilize said garment with respect to the user's body. To do so, it uses the loops on the garment, the grooves made in it at waist level or other similar elements. The purpose of the invention is to achieve a tightening device which can adapt to the different distances between the loops or similar to be used, by way of elements that can be replaced and which can be varied both in their operative length or, most specifically, in terms of the range of said length due to the elastic nature of its parts as well as their appearance. It is also object of the invention that both the loops used for assembling the tightening device, as well as the way in which said device is attached to the loops, are hidden, likewise with the same purpose of achieving an optimum appearance. The invention is therefore an accessory for garments. BACKGROUND OF THE INVENTION Tightening devices for garments, particularly trousers, have been well known for many years, and in this sense mention should be made of the U.S. Pat. No. 1,017,544, dated 13 Feb. 1912, in which the tightening device has a buckle, similar to that of a conventional belt, but which does not close over itself as in the case of belts but which, rather, is formed by two separate parts which, together, affect only around half of the waist band of the trousers and are attached to the latter by buttons and button holes. The appearance and the features of this tightening device provide the user with more or less the same performance as that of a conventional belt. A more developed tightening device appears in the U.S. Pat. No. 4,800,594, dating back to 1987, in which the device uses a couple of loops on the trousers and materializes in a simple strip which, at each end, has “Velcro®” type adhesive elements which can be fixed to the respective loops by folding the strip back on itself. This solution is uncomfortable to use and is designed more as an aesthetic device than as a tightener, being used normally in pairs on both sides of the waist and comprising, in essence, an aesthetic element which improves the appearance of the garment at the waist but which does not participate in tightening the garment to stabilize it on the user's body. A more recent solution is that shown in the U.S. Pat. No. 5,566,397, which is a genuine tightener, which uses a couple of loops on the garment but where, in this case, the tightener materializes in two parts in the form of rings which are fixed to said loops. Attached immovably to one of these rings is a kind of belt which passes through the corresponding part to the other loop, doubling up on itself and becoming stabilized with the collaboration of a kind of central buckle. In this case, too, the result is a tightener with the appearance of a classic belt, particularly when the user's trousers are hidden on the side by the corresponding or complementary jacket. Moreover, due to the system of fastening to the loops, it means that these are on the whole visible and undergo noticeable deformation, due to the pulling effect of the tightener, which has very negative repercussions on the appearance of the whole. The applicant is the title holder of the invention patent P 200502173, in which he describes a tightener for garments formed by a central element which represents the support for the decorative development of the tightener, a central element of any appropriate length extended at each end with its respective tying or hooking elements which can easily be passed through the respective loops, being attached to the latter of doubling up on themselves, once again reaching the central element to be tied or fixed behind it, all of that with the necessary tension to achieve the sought-after tightening effect. With this solution, substantial improvement is achieved both in the appearance and handling of the tightener, even though there is still a series of problems such as the visibility of the loops used and the means of fastening the device to them, the impossibility of adjusting the tightener in terms of length, the difficulty in adapting it to the waist profile, particularly when the loops are far apart, as well as other problems which will become evident during the following description. DESCRIPTION OF THE INVENTION The tightener proposed in this invention represents a new technical development thanks to which the elasticity of the tightener is moved to the central element itself which, in addition, can be adjusted so that it is possible to maintain any degree of tightening irrespective of the varying distances between loops that may exist on different garments worn by the same user. To do so, and in a more specific way, the aforementioned central element is divided into two halves linked to one another by way of elastic parts which are fixed immovably to each of said halves. A further feature of the invention is that said elastic elements can be fastened to the two halves of the central element at different points along the length, so that the effective length of the tightener may be varied substantially, providing each half with a considerable length. A further feature of the invention is that the elastic elements will be visible, often participating in the aesthetic appearance of the central part. For that reason, it has been envisaged that these can be replaced by others, not only to vary the effective length of the tightener but also to change its appearance at will. Yet another of the feature of the invention is that it is envisaged that the elastic part relating to the two halves of the central element, or in due course to one of the elastic parts, should incorporate a element for fastening it to the trousers or garment in question, such as a clip, so that deformation is prevented from being produced in the area of the garment between the loops to which the tightener is fastened as such deformation would have subsequent negative repercussions on the appearance of the whole. Thus it is ensured that the tightener is perfectly adapted to the waist of the garment itself. In accordance with a preferential execution of the invention, pivotal longitudinal alignments can be established, conveniently set apart, on each one of the halves of the central element. The number of these will coincide with the elastic elements to be fastened between both halves. Each elastic element incorporates, at its end, some buttonholes or other orifices capable of receiving said pivotal elements in a stable manner. Thus, according to which of each pair of pivots is selected, an effective length for the tightener will be obtained, after which it can be lengthened elastically. It merely remains to mention that each half of the central element, as a means for fastening it to the loop or similar element on the garment, incorporates a kind of rigid hook, preferably of a good width but, of course, not as wide as the effective length of the loops themselves. The purpose of the aforementioned dimensions of these hooks is to minimize deformation of the respective loops, affecting them nearly wholly or in their entire length. Also, said loops thus remain hidden due to the fact that the aforementioned hooks are underneath with regard to the outside edge of the respective halves of the central element. It is also envisaged that one of these hooks should form a cross-arm clip which ensures that the tightener remains attached to the garment even when the other end becomes separated from it, thus avoiding its accidental falling down. The elastic elements which link the two halves of the central element can be several and independent or associated with one another in their middle area, of a single-part type, with this ( 5 ) forming an aesthetic enhancer which is visible when the two halves of the central element are duly separated. It is inter-changeable with other similar ones with the object of enhancing the possibilities of the tightener from an aesthetic viewpoint. DESCRIPTION OF THE DRAWINGS In order to complement the description being made and in order to improve the understanding of the characteristics of the invention, in accordance with a preferential example of its practical use, this document includes, as an integral part of the description, a series of drawings which, for illustrative purposes but not limited to, are represented in the following: FIG. 1 shows, from a frontal perspective, the garment tightening device made in accordance with the object of this invention. FIG. 2 shows a rear view of the whole represented in the above FIG. 1 . FIG. 3 shows another front view of the tightener device, similar to FIG. 1 , but in a situation of maximum lengthening of said device. FIG. 4 shows a rear view of the whole represented in the above FIG. 3 . FIG. 5 , finally, shows a profile or pattern detail of the tightener device in the position of the FIGS. 1 and 2 . PREFERENTIAL EXECUTION OF THE INVENTION Upon viewing the aforementioned figures, it may be observed how the garment tightening device proposed by the invention is formed by a central element divided into two halves or parts 1 and 2 in the form of appropriately decorated flat parts, which may partially overlap—as shown in FIGS. 1 and 2 —or be noticeably separate—as shown in FIGS. 3 and 4 —, in either case being linked by means of elastic elements ( 3 ), such as rubber strips, which permanently tend to pull said parts together ( 1 ) and ( 2 ). As has already been said, parts ( 1 ) and ( 2 ) are meant to be fastened to two of the loops ( 4 ) of the trousers, for which purpose on their rear side they have the appropriate attachments ( 5 ), in the form of hooks, which are meant to be attached to the loops ( 4 ), by preference of a length which is similar to but slightly less than the effective length of said loops, so as to ensure only minimum deformation thereof. One of these attachments or hooks ( 5 ) will be equipped with a hinge mechanism and will take on the form of a closed elastic clip or any other configuration or structure that allows keeping said attachment ( 5 ) permanently fixed to the corresponding loop ( 4 ), so as to ensure that when the tightening device becomes separated from its other attachment ( 5 ) and its corresponding loop ( 4 ), the device will remain attached to the trousers or garment through the other attachment or hook ( 5 ), which can only be undone separately in a required or deliberate way by opening the corresponding clip or hinge. This prevent the tightening device from accidentally falling to the ground when, for any reason, the garment is opened at waist level. The elastic elements ( 3 ), in other words the rubber strips, combine with several tubular elements ( 6 ), by preference made of metal, in the form of sockets which are duly decorated as they will affect decisively the appearance of the tightening device, particularly in its maximum length position as shown in FIGS. 3 and 4 . Said sockets correspond to a mere example of preferential practical execution as they can be substituted by any other kind of structure capable of grouping the elastic elements ( 3 ) properly, thus benefiting the appearance of the device. To acquire a “step-by-step” positional adjustment of the elastic elements ( 3 ) with regard to parts ( 1 ) and ( 2 ), in the example of practical execution in the figures it has been foreseen that on the rear of parts ( 1 ) and ( 2 ), which form the central element, a pair of pivotal alignments be established ( 7 - 7 ′), to be used selectively, whereas the elastic elements ( 3 ) are grouped in pairs, as may be observed in any of the figures from 2 to 4 , with each pair of elastic elements ( 3 ), though their corresponding decorative sockets ( 6 ), being fastened at their ends by means of a pair of flat grips ( 8 ) which, appropriately distant from one another, determine, together with the elastic elements themselves ( 3 ), several orifices ( 9 ), destined to their selective attachment to any of the pivots ( 7 ). In this way, and from the relatively short tightening device shown in FIG. 1 , the device can be increased in length considerably up to the position shown in FIG. 3 . From any of these two positions, it can be extended elastically by deforming or stretching its elastic elements ( 3 ), generating the appropriate tension on the user's waist by way of the loops ( 4 ) to which the two parts ( 1 ) and ( 2 ) forming the central part of the tightening device are attached. Of course, the fastening system described for the elastic elements with regard to the parts comprising the central element is merely given as an example and said fastening, the position of which can be adjusted, can be effected in numerous different way, such as for example establishing on the rear surface of parts ( 1 ) and ( 2 ) some longitudinal ‘plaques’ with appropriately distributed perforations into which the hooks at the ends of the elastic elements ( 3 ) can be placed, using elastically retractile ‘pins’ or any other suitable means. As may be observed from the figures, the configuration of parts ( 1 ) and ( 2 ) is such that the hooks ( 5 ) remain totally hidden and therefore totally hidden are the loops ( 4 ) to which they are attached, so that irrespective of the dimensions of said hooks ( 5 ) any noticeable deformation in the loops ( 4 ) is avoided. Even when such deformation were to occur, this would be invisible to the eye when the garment is being worn as may be seen in FIGS. 1 and 3 , all of that with the subsequent repercussions on an aesthetic level. Finally, it remains to be said, as already mentioned, that the elastic element ( 3 ) occupying the upper position or, in due course, in the upper and middle area of any other decorative element replacing the aforementioned enhancer sockets ( 6 ) covering the elastic elements, a clip ( 10 ) like that shown in FIG. 5 will be placed, with the purpose of being attached to the upper edge of the belt of the trousers or garment in question, corresponding with the front and middle point thereof, thus achieving stability for the garment-tightener, with the latter being perfectly adapted to the top edge of the garment, avoiding the garment's tendency to deform downward in the front between the two loops to which the device is attached, with the subsequent advantages on an aesthetic level, too.

The girdle comprises two parts or halves ( 1 - 2 ), connected to each other by means of elastic elements ( 3 ) covered by adornments in the form of shells ( 6 ) coaxially interconnected, or any other type of unitary or fragmented adornment, wherein the plastic elements ( 3 ) are fastened to the parts ( 1 ) and ( 2 ) by means of pivots ( 7 ) selectively usable in order to vary the effective length of the girdle, length which also varies depending on the elasticity of the elements ( 3 ). Each said part or half ( 1 ) and ( 2 ) incorporates at the free end and back face thereof hooks ( 5 ) for fastening to the clasps ( 4 ) of the garment, in such a way that said elastic elements ( 3 ) cause traction between the clasps producing the girdling of the garment. The middle area of the elastic elements ( 3 ) or more specifically of the adornments encapsulating same, is visible when the parts ( 1 ) and ( 2 ) are substantially spaced, directly affecting the appearance of the girdle and constituting a changeable element.

PRIORITY [0001] This application claims priority to and the benefit as a continuation application of U.S. patent application Ser. No. 11/338,988, entitled “Access Disconnection Systems And Methods,” filed Jan. 25, 2006, which is a continuation of U.S. Pat. No. 7,022,098, entitled “Access Disconnection Systems And Methods,” Ser. No. 10/120,703, filed Apr. 10, 2002, the entire contents of each of which are expressly incorporated herein by reference and relied upon. BACKGROUND OF THE INVENTION [0002] The present invention relates generally to patient access disconnection systems and methods for medical treatments. More specifically, the present invention relates to the detection of patient access disconnection, such as dislodgment of a patient access device during medical treatments or therapies including dialysis therapy. [0003] A variety of different medical treatments relate to the delivery of fluid to and/or from a patient, such as the delivery of blood between a patient and an extracorporeal system connected to the patient via a needle or needles or any suitable access device inserted within the patient. For example, hemodialysis, hemofiltration and hemodiafiltration are all treatments that remove waste, toxins and excess water directly from the patient's blood. During these treatments, the patient is connected to an extracoporeal machine, and the patient's blood is pumped through the machine. Waste, toxins and excess water are removed from the patient's blood, and the blood is infused back into the patient. Needles or other suitable access devices are inserted into the patient's vascular access in order to transfer the patient's blood to and from the extracoporeal machine. Traditional hemodialysis, hemofiltration and hemodiafiltration treatments can last several hours and are generally performed in a treatment center about three to four times per week. [0004] During any of these hemo treatments, dislodgment of the access device can occur, such as dislodgment of a needle inserted into the patient's vascular access including an arterio-venous graft or fistula. If not detected immediately, this can produce a significant amount of blood loss to the patient. The risks associated with a needle dislodgment are considerable. In this regard, important criteria for monitoring blood loss include, for example, the sensitivity, specificity and response time with respect to the detection of needle dislodgment. With increased levels of sensitivity, specificity, and response time, the detection of needle dislodgment can be enhanced, and blood loss due to dislodgment can be minimized. [0005] Typically, patients undergoing medical treatment, such as hemodialysis, hemofiltration or hemodiafiltration, are visually monitored in order to detect needle dislodgment. However, the needle may not be in plain view of the patient or medical staff (i.e., it may be covered by a blanket) such that it could delay detection and, thus, responsive actions to be taken in view of dislodgment, such as stopping the blood pump of the extracorporeal machine to minimize blood loss to the patient. [0006] Moreover, in view of the increased quality of life, observed reductions in both morbidity and mortality and lower costs than in-center treatments, a renewed interest has arisen for self care and home hemo therapies. Such home hemo therapies (whether hemodialysis, hemofiltration or hemodiafiltration) allow for both nocturnal as well as daily treatments. During these self care and home hemo sessions, especially during a nocturnal home hemo session, when the patient is asleep, dislodgment risks are more significant because nurses or other attendants are not present to detect the dislodgment. [0007] Although devices that employ a variety of different sensors are available and known for detecting and/or monitoring a variety of different bodily fluids, these devices may not be suitably adapted to detect needle dislodgment. For example, known devices that employ sensors including pH, temperature and conductivity have been utilized to detect bedwetting and diaper wetness. Further, devices that employ pressure sensors and/or flow sensing devices are known and used during medical treatment, such as dialysis therapy, to monitor fluid flow including blood flow to and/or from the patient. However, these types of detection devices may not provide an adequate level of sensitivity and responsiveness if applied to detecting blood loss from the patient due to needle dislodgment. Although venous pressure is known to be used to monitor needle dislodgment, it is not very sensitive to needle drop-out. [0008] Additional other devices and methods are generally known to monitor vascular access based on the electrical conductivity of blood. For example, Australian Patent No. 730,338 based on PCT Publication No. WO 99/12588 employs an electrical circuit which includes two points through which current is induced into blood flowing in an extracorporeal circuit that forms a closed conductor loop. Current is induced in blood using a coil that is placed around the outside of the tubing of the blood circuit. Thus, each coil does not directly contact the blood as it circulates through the tubing. In this regard, a current is generated into the blood flowing in the extracorporeal circuit by an alternating current that flows through one of the coils. The second coil is then utilized to measure a change in amperage of the induced current as it flows through the blood circuit. [0009] In this regard, electrical current is coupled to a blood treatment system that includes a number of high impedance components, such a blood pump, air bubble traps, pinch clamps and/or the like. Because of the large impedance of the conducting fluid loop (due to the peristaltic pump and other components), the induction and detection of a patient-safe current requires an impractically complex design of the coil and system. Further, a high level of noise would necessarily result from the use of such levels of induced current. This can adversely impact the sensitivity of detection. If lower currents are used, the field coil would have to be increased in size to detect such low current levels. This may not be practical in use, particularly as applied during dialysis therapy. [0010] PCT Publication No. WO 01/47581 discloses a method and device for monitoring access to the cardiovascular system of a patient. The access monitoring employs an electrical circuit which can generate and detect a current at separate points along a blood circuit connected to the patient. Current is injected into blood using capacitive couplers that each have a metal tube placed around the blood circuit tubing. In this regard, the metal tube defines a first plate of a capacitor; the blood circuit tubing defines the dielectric; and the blood inside of the blood circuit tubing defines the second plate of the capacitor. [0011] The generator applies a potential difference between a pair of capacitive couplers to generate a current in blood flowing through the blood circuit. A detector utilizes an additional and separate pair of capacitive couplers to measure the current along at least one section of the venous branch between a first contact point and the venous needle. The change in voltage (dV) can then be determined based on a measured change in current and compared to a reference range (I) to monitor access conditions. In this regard, PCT Publication No. WO 01/47581 requires a complex circuit design that utilizes multiple sets of capacitive couplers to monitor vascular access conditions. This can increase the cost and expense of using same. [0012] Further, the mere use of capacitive coupling to inject an electric signal in the blood circuit and/or for detection purposes can be problematic. In this regard, the signal must pass through the tubing of the blood circuit as the tubing acts as a dielectric of the capacitor. This may cause an excess level of noise and/or other interference with respect to the detection of changes in vascular access conditions. [0013] In this regard, it is believed that known devices, apparatuses, systems, and/or methods that can be used to monitor a patient's access conditions may not be capable of detecting change in access conditions, such as in response to needle drop out, with sufficient sensitivity and specificity to ensure immediate detection of blood loss such that responsive measures can be taken to minimize blood loss. As applied, if twenty seconds or more of time elapses before blood loss due to, for example, dislodgment of the venous needle, over 100 milliliters in blood loss can occur at a blood flow rate of 400 ml/min, which is typical of dialysis therapy. Thus, the capability to respond quickly upon immediate detection of dislodgment of an access device, such as a needle, from a patient is essential to ensure patient safety. [0014] Accordingly, efforts have been directed at designing apparatuses, devices, systems and methods for detecting changes in access conditions, such as in response to needle dislodgment, wherein detection is sensitive, specific and immediate in response to such access changes such that responsive measures can be suitably taken to minimize blood loss from the patient due to same. SUMMARY OF THE INVENTION [0015] The present invention provides improved devices, apparatuses, systems, and methods for detecting dislodgment or disconnection of an access device, such as dislodgment of a needle inserted in a patient during dialysis therapy. The devices, apparatuses, systems, and methods of the present invention utilize an electrical circuit with a number of electrical contacts which are in fluid contact with the fluid circuit such that an electrical signal can be injected into at least a segment including, for example, a loop defined along at least a portion of the conducting fluid circuit. In this regard, a direct-contact measurement can be used to provide immediate detection of a change in an electrical value in response to a change in access conditions, such as a change in impedance due to dislodgment of a needle or other access device from the patient during medical therapy including, for example, dialysis therapy and medication delivery. [0016] An advantage of the present invention is to provide an improved device, apparatus, system and/or method for detecting access disconnection. [0017] A further advantage of the present invention is to provide an improved device, apparatus, system and/or method for detecting dislodgment of an access device from a patient during medical therapy including dialysis therapy. [0018] Another advantage of the present invention is to provide an improved device, apparatus, method and/or system for detecting needle drop-out during dialysis therapy. [0019] Yet another advantage of the present invention is to provide a sensitive, specific and responsive apparatus and/or device for detecting access disconnection during selfcare and home hemo treatments. [0020] Moreover, an advantage of the present invention is to provide a viable device or apparatus for allowing a patient to self administer or other non-medical personnel in a non-medical facility a dialysis therapy that uses a portion of the patient's circulatory system. [0021] Still further, an advantage of the present invention is to provide an improved apparatus for detecting access disconnection that uses a direct conductivity measurement. [0022] Yet still further, an advantage of the present invention is to provide an access disconnection detection device, method and/or system that employs an electrical circuit in fluid and electrical contact with blood flowing through a blood circuit allowing direct conductivity measurements to be made. [0023] Furthermore, an advantage of the present invention is to provide an improved device, system and method for monitoring and/or controlling blood loss from a patient. [0024] Another advantage of the present invention is an improved method for dialysis that employs an apparatus, device and/or system capable of detecting access disconnection, such as dislodgment of a needle inserted into a patient through which blood flows during dialysis therapy and minimizing any resulting blood loss. [0025] Yet another advantage of the present invention is an improved device for connecting an electrical contact to a fluid circuit allowing fluid and electrical communication between the electrical contact and fluid flowing through the fluid circuit. [0026] Still another advantage of the present invention is an improved apparatus, device, system and/or method for detecting access disconnection, such as needle drop-out during dialysis therapy, with enhanced sensitivity, accuracy and responsiveness. [0027] Yet still another advantage of the present invention are improved apparatuses, devices, systems and/or methods for the detection of fluid loss due to, for example, dislodgment of a single access device during medical therapies, for example, medication delivery and single needle hemo therapies. [0028] Additional features and advantages of the present invention are described in, and will be apparent from, the following Detailed Description of the Invention and the figures. BRIEF DESCRIPTION OF THE FIGURES [0029] FIG. 1A illustrates a schematic view of an embodiment of the present invention showing two needles insertable within a patient through which blood flows to and from an extracorporeal system. [0030] FIG. 1B illustrates a schematic view of an embodiment of the present invention capable of detecting needle dislodgment during dialysis therapy. [0031] FIG. 1C illustrates a perspective view of an embodiment of the present invention showing access disconnection detection capabilities during medical therapies administered via a single needle. [0032] FIG. 2A illustrates an exploded view of an electrical contact coupling device in an embodiment of the present invention. [0033] FIG. 2B illustrates a side sectional view of the coupling device of FIG. 2A in an embodiment of the present invention. [0034] FIG. 2C illustrates another embodiment of the coupling device of the present invention. [0035] FIG. 2D illustrates another embodiment of the coupling device of the present invention showing a threaded engagement between the components of same. [0036] FIG. 2E illustrates a sectional view of FIG. 2D . [0037] FIG. 2F illustrates another embodiment of a coupling device of the present invention. [0038] FIG. 3 schematically illustrates an embodiment of the present invention relating to processing of a measurable voltage signal to correct for changes in baseline impedance during treatment. [0039] FIG. 4A schematically illustrates a hemodialysis machine in an embodiment of the present invention. [0040] FIG. 4B schematically illustrates a hemodialysis machine coupled to a patient's access via a tubing set in an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION [0041] The present invention provides medical devices, apparatuses, systems and methods for detecting access disconnection. More specifically, the present invention provides medical devices, apparatuses, systems, and methods that employ, in part, an electrical circuit with electrical contacts in fluid contact and electrical communication with a fluid circuit allowing a direct conductivity measurement to be used such that dislodgment of a needle or other access device through which fluid flows between a patient and the fluid circuit can be immediately detected. In this regard, fluid loss (i.e., blood loss) due to, for example, dislodgment of a needle from a patient undergoing medical treatment, such as dialysis therapy, medication delivery or the like, can be controllably minimized. [0042] It should be appreciated that the present invention is not limited to the detection of needle dislodgment but can be utilized to detect the dislodgment or disconnection of any suitable access device. As used herein, the term “access disconnection” or other like terms means any suitable condition or event which can cause a loss or leak of an electrically conductive fluid flowing along a fluid circuit connected to the patient provided that a change in the electrical continuity between electrical contacts coupled to the fluid circuit can be detected. It should be appreciated that a change in the electrical continuity as measured by an electrical value, such as impedance, may be detected even in the absence of dislodgment of an access device from the patient. The term “access device” as used herein or other like terms means a suitable device that can be inserted within a patient such that fluid, including blood, can pass to, through and/or from the patient via the access device. The access device can include a variety of different and suitable shapes, sizes and material make-up. Examples of an access device includes needles, catheters, cannulas or the like. The access device can be composed of any suitable material including, for example, stainless steel, plastic or like biocompatible materials. [0043] Although in the embodiment set forth below the apparatus and/or device is designed for use in a dialysis therapy, such as hemodialysis, hemofiltration or hemodiafiltration, it should be noted that the present invention can be used in a number of different medical therapies that employ a variety of different and suitable fluid systems, such as extracorporeal blood systems. For example, the invention of the present application can be used during intravenous infusion that can employ the use of a single needle insertable within the patient for delivering a medical solution or drug, blood, blood products, processed blood or the like between the patient and the fluid system. In addition, the present invention can be used in plasma exchange therapies, where a membrane is used to separate whole blood into plasma and cellular components. [0044] With respect to dialysis therapy, the present invention can be used in a variety of different therapies to treat kidney failure. Dialysis therapy as the term or like terms are used throughout the text is meant to include and encompass any and all forms of therapies that utilize the patient's blood to remove waste, toxins and excess water from the patient. Such therapies include both intermittent, including hemodialysis, hemofiltration and hemodiafiltration, and continuous therapies used for continuous renal replacement therapy (CRRT). These continuous therapies include slow continuous ultrafiltration (SCUF), continuous veno venous hemofiltration (CVVH), continuous veno venous hemodialysis (CVVHD), and continuous veno venous hemodiafiltration (CVVHDF). Dialysis therapy can also include peritoneal dialysis, such a continuous ambulatory peritoneal dialysis, automated peritoneal dialysis and continuous flow peritoneal dialysis. Further, although the present invention, in an embodiment, can be utilized in methods providing a dialysis therapy for patients having chronic kidney failure or disease, it should be appreciated that the present invention can be used for acute dialysis needs, for example, in an emergency room setting. Lastly, as one of skill in the art appreciates, the intermittent forms of therapy (i.e., hemofiltration, hemodialysis and hemodiafiltration) may be used in the in center, self/limited care as well as the home settings. [0045] In an embodiment, the present invention includes an electrical circuit with a number of electrical contacts, preferably a pair of electrical contacts, in fluid contact and electrical communication with the fluid circuit. The electrical contacts can include any suitable device through which electrical connection can be made with the fluid circuit thereby defining a conductive pathway or conductor loop therein. Changes in an electrical value or any suitable parameter associated with the conductor loop can then be monitored in response to changes in access conditions as described below. In an embodiment, the electrical contact includes an electrode which can be coupled to the fluid circuit such that an electrical connection can be made in fluid contact with fluid flowing through the fluid circuit as discussed below. [0046] For example, a constant current or other suitable electrical signal can be injected into the fluid circuit via an electrode pair in contact with fluid flowing between the electrodes thereby defining a loop along at least a portion of the fluid circuit. A change in an electrical value, preferably impedance, can then be measured in response to access disconnection. This can provide a direct conductivity measurement capable of detecting a change in impedance or other suitable electrical parameter of the fluid, such as an electrically conductive fluid including blood, medical solutions or the like, as it flows between a patient and a fluid system (i.e., an extracorporeal blood system) via a needle, needles or other access device(s) inserted within the patient. [0047] In this regard, the present invention can effectively detect dislodgment of a needle (e.g., a venous needle and an arterial needle) or other access device through which blood or other suitable fluid can flow, for example, to, through and from the patient, such as a blood circuit used during dialysis therapy. The detection capability of the present invention is believed to be immediate based on the measurable change in, for example, impedance of the electrically conductive fluid or fluids due to fluid loss resulting from disconnection of the access device from the patient. [0048] The immediate detection capabilities of the present invention are important, particularly as applied to dialysis therapy where a significant amount of blood loss can occur within a relatively short period of time if delays in detection and responsive actions to stop the blood loss occur. Under typical dialysis conditions, if 20 seconds or more time elapses before blood loss due to dislodgment is detected and stopped, over 100 milliliters of blood can be lost based on typical blood flow rates of 400 milliliters/minute. [0049] Applicants have discovered that the present invention can detect access disconnection, particularly in response to venous needle dislodgment during dialysis therapy, with a high degree of sensitivity and specificity in addition to its immediate detection capabilities. The direct-contact measurement of the present invention is capable of detecting a change of an electrical value, preferably impedance, due to needle dislodgment or the like as the blood flows through the blood circuit during dialysis therapy. As used herein, the term “electrical value” or other like terms means any suitable electrical parameter typically associated with electrical circuitry including, for example, impedance, resistance, voltage, current, rates of change thereof and combinations thereof. The detection of a change in impedance or the like is an indication that the needle has become dislodged or other like condition has occurred. It is noted that the detection capabilities of the present invention can also effectively detect blood loss during medical therapy even if the needle or needles have not become dislodged or at least not entirely dislodged. In this regard, the present invention can be effectively utilized to controllably minimize blood loss from the patient based on the ability of the present invention to immediately measure a change in impedance or the like due to blood loss with a high degree of sensitivity and specificity. [0050] The devices and apparatuses of the present invention can include a variety of different components and configurations depending on the applied medical therapy such that fluid loss, particularly blood loss due to needle dislodgment or the like, can be effectively monitored. Multiple Access Disconnection [0051] Referring now to FIG. 1A , an embodiment of the apparatus 10 of the present invention includes a pair of electrical contacts 12 in fluid contact with a blood tubing set 14 of a blood circuit 16 . The blood circuit 16 connects a patient 18 to an extracorporeal blood system 20 as applied to, for example, dialysis therapy including hemodialysis, hemofiltration, hemodiafiltration, continuous renal replacement or the like or plasma therapies. The pair of electrical contacts 12 includes a first electrical contact 22 and a second electrical contact 24 which are attached to a respective first tube member 26 and second tube member 28 of the blood circuit 16 . The first tube member 26 is connected to a venous needle or other suitable access device inserted into a vascular access region (not shown) of the patient. The second tube member 28 is connected to an arterial needle or the like also inserted into a vascular access region (not shown) of the patient. During dialysis therapy, for example, blood flows from the patient 18 through the arterial needle to the extracorporeal blood system 20 includes, for example, a dialysis machine, via the second tube member 28 where the blood is treated and delivered to the patient 18 through the venous needle via the first tube member 26 . [0052] As the blood flows through the blood circuit during dialysis therapy, a constant electric current or the like generated by a controller 29 can be injected or passed into the flowing blood via the electrical contact pair, preferably an electrode pair as described below. The electrode pair connected to the controller 29 or other suitable electronic device can then be used to measure a voltage change across an unknown fluid (e.g., blood) impedance or other like electrical value to detect a change in impedance or the like across the vascular access region. In an embodiment, one electrode can be used to inject the electrical signal into the fluid circuit while the other electrode of the pair can be used to sense a change in the electrical value and pass an electrical signal indicative of the same to the controller for processing and detection purposes. Upon dislodgment of at least one of the venous needle and arterial needle from the blood circuit or other suitable condition, an immediate and detectable increase in impedance or the like can be measured as compared to the impedance or other suitable parameter measured under normal operating conditions. [0053] It should be appreciated that the present invention as embodied in FIG. 1A can be modified in a variety of suitable ways depending on the medical therapy as applied. For example, the venous and arterial needles can be inserted into the vascular access of the patient on any suitable part of the patient's body, such as the upper arm, lower arm, upper thigh area or the like during dialysis therapy. As previously discussed, the present invention can be applied to a variety of different medical therapies including intravenous infusions, plasma exchanges, medication delivery, drug delivery, blood delivery and dialysis therapies (i.e., hemofiltration, hemodialysis, hemodiafiltration and continuous renal replacement). [0054] As illustrated in FIG. 1B , an embodiment of an apparatus 30 of the present invention is shown as applied during dialysis therapy. In an embodiment, the present invention includes a venous needle 32 and arterial needle 34 inserted within a patient access 36 . The venous needle 32 and arterial needle 34 are connected to the dialysis system 35 via a number of tube members 38 that connect the various components of the dialysis system 35 including, for example, a venous drip chamber 40 , a dialyzer 42 , an arterial drip chamber 44 and a blood pump 46 . It should be appreciated that one or more of the components of the dialysis system can be provided within a dialysis machine coupled to the blood circuit. As shown in FIG. 1B , a first electrical contact coupling device 48 and a second electrical contact coupling device 50 are positioned between the dialysis system 35 and the venous needle 32 and the arterial needle 34 . As used herein, the term “electrical contact coupling device,” “coupling device” or other like terms means any suitable device that can be used to connect an electrical contact to the fluid circuit. In an embodiment, the electrical contact coupling device can be used to contact the electric contact to the fluid circuit allowing fluid contact and electrical connection with the fluid flowing through the fluid circuit as described below. [0055] In an embodiment, the electrical contact pair, preferably an electrode pair, are connected to a controller 52 or other suitable electronic device. The controller can be used to inject an electric signal via the electrode pair and into the blood and/or other fluid as it flows through the blood circuit. This provides a conductor loop along which changes in electrical parameters or values can be measured. The controller 52 which is coupled to the electrode pair can also be used to measure this change. It should be appreciated that the controller can include a single electronic device or any suitable number of devices in electrical connection with the electrical contacts to input an electrical signal into the blood circuit thereby defining a conductor loop, to measure a change in an electrical parameter or value associated with the conductor loop and/or perform any other suitable tasks, such as processing the detectable signal as discussed below. [0056] Preferably, the electrical signal is generated from a constant current that is supplied to the electrodes until dislodgment occurs. The voltage across an unknown impedance of the fluid (e.g., blood) circulating through the blood circuit can then be measured (not shown) to detect a change in impedance due to changes in access conditions. However, it should be appreciated that any suitable electrical parameter and changes thereof can be monitored to detect needle drop-out or the like as previously discussed. [0057] As demonstrated below, the detection capabilities of the present invention are highly sensitive, specific and virtually immediate in response to access disconnection, such as needle dislodgment. Further, the electronic circuit of the present invention is relatively simple in design such that preferably one electrode pair is necessary to conduct direct conductivity measurement. This can reduce costs and effort as compared to known vascular access monitoring techniques that only employ non-invasive detection techniques, such as, capacitive couplers and induction coils as previously discussed. [0058] Applicants have discovered that the total impedance measured (“Z”) can be modeled as two lumped impedances in parallel with one impedance (“ZD”) being produced by the pump segment, the dialyzer, the drip chambers and/or other suitable components of the dialysis system and/or the like. The other resistance impedance component (“ZP”) is formed by the patient's vascular access and associated tubing which carries blood to and from the vascular access and/or the like. In this regard, the total impedance measured can be characterized as a function of both ZD and ZP as follows: [0000] Z =(1/ ZD+ 1/ ZP )−1 [0059] Despite this parallel impedance, applicants have discovered that the electrical contacts in connection with the controller can be used to measure a change in impedance along the conductor loop as blood flows through the blood circuit in response to access disconnection, such as needle dislodgment. If needle dislodgment occurs, the conductor loop along at least a portion of the fluid circuit changes from a closed circuit to an open circuit and thus Z=ZD where ZP approaches infinity. In this regard, the direct conductive measurement capabilities of the present invention can be effectively used to detect access disconnection. [0060] Applicants note that the ZD component can produce a level of electrical interference associated with the time-varying high impedance of the components of a medical system coupled to the fluid circuit, such as a dialysis system and its components including, for example, a blood pump, a drip chamber and/or the like. Applicants have discovered that the interference due to the ZD component can be effectively eliminated, or at least reduced, if necessary. In an embodiment, the signal associated with the detection of Z or the like can be further processed as discussed below. Alternatively, in an embodiment, the electrical circuit of the present invention can be designed to block or bypass one or more components of the dialysis system from the conductor loop or pathway defined along the blood circuit as described below. In this regard, the accuracy, sensitivity and responsiveness with respect to the detection of access disconnection can be enhanced. [0061] In an embodiment, a third electrical contact point 53 can be utilized to minimize or effectively eliminate the interferences with respect to the high impedance components coupled to the blood circuit, such as the blood pump and the like. The additional contact point can be made in any suitable way. For example, the third contact point can be an electrode or other suitable device through which electrical continuity can be established between it and one of the electrodes of the coupling devices. In an embodiment, the third electrical contact can be attached to a fluid circuit in fluid and electrical communication with fluid flowing through same. [0062] The third contact point 53 can be positioned at any suitable position along the blood circuit. Preferably, the third contact point 53 is positioned at any suitable location between the blood pump 46 and the coupling device 50 as shown in FIG. 1B . An equalization potential can then be applied between the third contact point 53 and the electrode of the coupling device 50 . The potential is applied at a voltage that is equal to the potential applied between the electrodes of the first coupling device 48 and the second coupling device 50 . [0063] This effectively causes the electric current or the like, once injected into the blood circuit, to bypass one or more of the components of the dialysis system. In an embodiment, the third contact point 53 can be positioned such that the electric current or the like would effectively bypass all of the components of the dialysis system as shown in FIG. 1B . Single Access Disconnection [0064] The electrical contacts of the present invention can be positioned in any suitable location relative to the needle, needles or suitable access device inserted within the patient. As illustrated in FIG. 1C , an embodiment of the present invention as applied with respect to the detection of access detection, such as the dislodgment of a single access device inserted within the patient is shown. This type of application is applicable to a variety of different and suitable medical therapies administered via a single access device, such as a single needle, including intravenous infusion and dialysis therapy including hemodialysis, hemofiltration, hemodiafiltration and continuous renal replacement. [0065] As applied, an electrically conductive fluid, such as blood, a blood product, a medical fluid or the like flows between the patient and a fluid system via a single access device. Dislodgment detection of a single access device can include, for example, the detection of needle dislodgment during the delivery of any suitable and electrically conductive fluid or fluids including, for example, blood or medical drug or solution (i.e., a medication contained in an electrically conductive fluid, such as saline), processed blood, blood products, intravenous solutions, the like or combinations thereof. The fluid delivery can be made between an suitable container, such as blood bags or like fluid delivery devices, and a patient. In this regard, immediate and responsive detection of access disconnection via the present invention can be effectively utilized to monitor and control the transfer of blood or a medical fluid, such as a medication or drug, during medical therapy administered via a single needle. [0066] As shown in FIG. 1C , an embodiment of the apparatus or device 54 of the present invention includes an access device 56 ; such as a needle, inserted into a blood vessel 58 within a needle insertion site 60 of the patient 62 . The needle 56 is connected to the fluid system 63 , such as a fluid infusion system, via a tube member 64 . The infusion system includes, for example, an infusion pump 66 for transferring the blood or the like from a container 68 (e.g., blood bag) to the patient. A first electrical contact 70 is spaced apart from the needle 56 along the tube member 64 and a second electrical contact 72 is attached to the patient near the insertion site 60 . The first electrical contact 70 is in fluid contact with the fluid as it flows from the delivery container 68 to the patient. [0067] In this configuration, the first and second electrical contacts, preferably electrodes, can be used to monitor changes in an electrical value, preferably impedance, within a loop formed by at least a portion of the fluid circuit as an electric signal passes therein. The electrical contact points can be coupled to an electronic device 74 which is capable of processing a detectable signal transmitted through the electrodes in response to a change in impedance or the like due to dislodgment of the single access device as described in detail below. Preferably, the electrical signal is generated by a constant current supplied to the electrodes such that a direct conductivity measurement can be conducted to detect a change in impedance or the like in response to changes in vascular access conditions, such as dislodgment of the access needle. [0068] It is believed that the measured impedance, in the single needle application, is a function of both the impedance of the fluid (i.e., blood) and the impedance as measured across the insertion site. In this regard, the electronic device 74 can be adjusted to detect the impedance at the level equivalent to the combined impedance of all items of the electrical path (i.e., the conductive fluid in the tube, needle, blood stream of venous vessel, body tissue, impedance across the skin with respect to the sensing electrode 72 and the like). Electrical Contacts [0069] As previously discussed, the electrical contacts of the present invention are in fluid contact with the fluid as it flows through the fluid circuit. In this regard, the electrical contacts allow for a direct conductivity measurement which is capable of immediately detecting, with high sensitivity and specificity, a change (e.g., an increase) in impedance or the like due to access disconnection, such as dislodgment of a venous needle (arterial needle or both) from the blood circuit during dialysis therapy. [0070] The electrical contacts can be composed of any suitable conductive and biocompatible material, such as, any suitable electrode material including stainless steel, other suitable conductive materials or combinations thereof. It is essential that the electrode material is biocompatible. [0071] It should be appreciated that the electrical contacts can be constructed in a variety of different shapes and sizes, illustrative examples of which are described below. For example, the electrical contacts can be configured or designed as a plaster electrode which includes an agent capable of expanding when in contact with moisture. The agent can include a variety of suitable materials including gels that are known to expand more than ten times in volume upon contact with moisture. [0072] In an embodiment, the plaster electrode can be utilized to detect fluid (i.e., blood leakage) at an insertion site of an access device insertable within a patient during the administration of medical therapy via a single access device as previously discussed. Upon contact with the fluid, the plaster electrode would necessarily expand to such an extent that the electrode contact is broken, thus causing a detectable increase in impedance of the fluid as it flows from the fluid system to the patient via the needle. [0073] In an embodiment, one or more electrodes (not shown), such as one or more plaster electrodes as previously discussed, can be used in combination with the electrical contact pair as shown, for example, in FIGS. 1A and 1B . For example, a plaster electrode can be attached to the patient near the insertion site of either or both of the arterial and venous needles. In this regard, the plaster electrode(s) can be utilized to detect leakage of fluid, such as blood, from the insertion site of the access device(s). [0074] In an embodiment, an electrode pair is coupled to the blood circuit in an invasive manner (illustrated in FIGS. 2A-2C as discussed below) such that the electrodes contact the blood as previously discussed. An excitation source that includes a constant current source or the like can be applied to the electrodes to inject an electric signal into the blood circuit thereby defining a conductor loop along which direct conductivity measurements can be performed. [0075] To ensure patient safety, the excitation source is typically isolated from the instrument power. Preferably, the excitation source produces a constant electrical current that passes through the blood via the electrodes. Any suitable amount of current can be generated for detection purposes. In an embodiment, the electrical current as it passes through the blood is maintained at a level of about 10 microamperes or less, preferably about 5 microamperes or less. It should be appreciated that the present invention can be operated at low levels of current (e.g., 10 microamperes or less) such that the level of current has negligible, if any, effect on the health and safety of the patient. [0076] It should be appreciated that the impedance or other suitable parameter can be measured and calculated in a variety of different and suitable ways. For example, the amplitude, phase and/or frequency of the constant current excitation source can be measured and varied during the detection of a change in impedance. Impedance levels can then be detected by measuring the voltage across the electrodes In this regard, the amplitude, frequency and/or phase of the voltage can then be measured and utilized in combination with the measured amplitude, frequency and/or phase of the excitation source to calculate blood impedance levels based on derivations or equations which are typically used to calculate impedance. [0077] The electrical contacts can be connected to the blood circuit in a variety of different and suitable ways. For example, the electrical contacts can be an integral component of the extracorporeal system, a disposable component that can be connected and released from the tubing members of the blood circuit, a reusable component that can be autoclaved between uses, or the like. Electrical Contact Coupling Device [0078] In an embodiment, the apparatus of the present invention includes an electrical contact coupling device that can be utilized to secure the electrical contacts, preferably electrodes, to the blood circuit such that the electrodes effectively contact the blood and, thus, can be used to effectively monitor changes in access conditions as previously discussed. The coupling device of the present invention can also be designed to facilitate the protection of the user against contact with potential electrical sources. In an embodiment, the device can include a conductive element connected to the tube through which a medical fluid, such as blood, can flow wherein the conductive element has a first portion exposed to the medical fluid and a second portion external to the tube. [0079] The coupling device of the present invention can include a variety of different and suitable configurations, components, material make-up or the like. In an embodiment, the present invention can include a device for connecting an electrical contact to a fluid conduit providing fluid and electrical communication between the electrical contact and fluid flowing through the fluid conduit. The device can include a first member including an annular portion capable of accommodating the electrical contact and a first stem portion connected to the annular member wherein the stem portion has an opening extending therethrough to the annular portion; a second member including a base portion with a groove region and a second stem portion with an opening extending therethrough to the groove region allowing the first member to be inserted and secured to the second member; and a contact member adapted to fit the first and second stem portions allowing the contact member to abut against at least a portion of the electrical contact member allowing an electrical connection to be made between the electrical contact and the contact member. Illustrative examples of the electrical contact coupling device of the present invention are described below. [0080] As illustrated in FIGS. 2A and 2B , the electrical contact coupling device 80 includes a probe member 82 that has a cylindrical shape with an opening 84 extending therethrough. In this regard, an electrical contact, preferably an electrode 86 having a cylindrical shape can be inserted into the opening 84 such that the electrode 86 is secure within the probe member 82 . In an embodiment, the probe member 82 has a channel 85 extending along at least a portion of the opening 84 within which the electrode 86 can be inserted into the probe member 82 . A tube member, for example, from a blood tubing set, connector tube member of a dialysis machine or the like, can be inserted into both ends of the opening 84 of the probe member 82 in contact with an outer portion of the channel 85 allowing blood or other suitable fluid to make fluid contact with the electrode 86 in any suitable manner. The electrode 86 has an opening 88 that extends therethrough within which blood (not shown) or other suitable fluid from the fluid circuit can flow. In an embodiment, the diameter of the opening 88 of the electrode 86 is sized to allow blood flow through the electrode 86 such that blood flow levels under typical operating conditions, such as during dialysis therapy, can be suitably maintained. In this regard, the coupling device of the present invention can be readily and effectively attached to a fluid circuit, including a blood circuit or the like, for use during medical therapy including, for example, dialysis therapy. It should be appreciated that the coupling device 80 of the present invention can be attached to the fluid circuit in any suitable way such that electrical and fluid connection can be made with the fluid flowing through the fluid circuit. [0081] The probe member 82 also includes a stem portion 90 that extends from a surface 92 of its cylindrical-shaped body. The stem portion 90 has an opening 93 that extends therethrough. In an embodiment, the stem portion 90 is positioned such that at least a portion of the electrode 86 is in contact with the opening 93 of the stem portion 90 . [0082] In order to secure the electrode 86 to the blood circuit, the coupling device 80 includes a socket member 94 that includes a body portion 96 with an opening 98 for accepting the probe member 82 and for accepting a blood tube member (not shown) of the blood circuit such that blood directly contacts the electrode as it circulates through the blood circuit during dialysis therapy. In an embodiment, the socket member 94 includes a stem portion 100 extending from the body member 96 wherein the stem portion 100 includes an opening 102 extending therethrough. As the probe member 82 is inserted through the opening 98 of the body member 96 , the stem portion 90 of the probe member 82 can be inserted into the opening 102 of the stem portion 100 of the body 96 of the socket member 94 . [0083] In an embodiment, the socket member 94 includes a groove region 104 extending along at least a portion of the body 96 of the socket member 94 . In this regard, the probe member 82 can be inserted through the opening 98 and then moved or positioned into the groove region 104 to secure the probe member 82 within the body 96 of the socket member 94 . [0084] In an embodiment, the coupling device 80 includes an electrical contact member 106 that is inserted within the opening 102 of the stem portion 100 of the body 96 of the socket member 94 such that the electrical contact member 106 extends through the opening 93 of the stem portion 90 of the probe member 82 to contact at least a portion of a surface 108 of the electrode 86 . [0085] The electrical contact member 106 is utilized to connect the electronics (not shown) of, for example, the excitation source, a signal processing device, other like electronic devices suitable for use in monitoring and/or controlling changes in access conditions, such as needle dislodgment. The electrical contact member 106 can be made of any suitable material, such as any suitable conductive material including, stainless steel, other like conductive materials or combinations thereof. In order to secure the electrical contact member 106 in place, a contact retainer member 110 is inserted within the opening 102 of the stem portion 100 at an end region 112 thereof. [0086] In an embodiment, the coupling device is mounted to a dialysis machine, device or system in any suitable manner. For example, the coupling device can be mounted as an integral component of the dialysis machine. As well, the coupling device can be mounted as a separate and/or stand alone component which can interface with any of the components of the apparatus and system of the present invention. In an embodiment, the coupling device 80 can be insertably mounted via the stem portion 100 of the socket member 94 to a dialysis machine or other suitable components. [0087] It should be appreciated that the electrical contact coupling device can include a variety of different and suitable shapes, sizes and material components. For example, another embodiment of the coupling device is illustrated in FIG. 2C . The coupling device 114 in FIG. 2C is similar in construction to the coupling device as shown in FIGS. 2A and 2B . In this regard, the coupling device 114 of FIG. 2C can include, for example, a cylindrical-shaped electrode or other suitable electrical contact, a probe member for accepting the electrode and securing it in place within a socket member of the sensing device. The probe member includes a stem portion that is insertable within a stem portion of the socket member. An electrical contact member is insertable within the stem portion such that it can contact the electrode. The coupling device of FIG. 2C can also include a contact retainer member to hold the electrical contact member in place similar to the coupling device as shown in FIGS. 2A and 2B . [0088] As shown in FIG. 2C , the probe member 116 of the electrical contact coupling device 114 includes a handle 118 which can facilitate securing the probe member 116 within the socket member 120 . The handle 118 , as shown, has a solid shape which can facilitate the use and manufacture of the coupling device 114 . In addition, the stem portion (not shown) of the probe member 116 is larger in diameter than the stem portion of the probe member as illustrated in FIG. 2A . By increasing the stem size, the probe member can be more easily and readily inserted within the socket member. Further, the probe member is greater in length as compared to the probe member as shown in FIGS. 2A and 2B such that the end regions 122 of the probe member 116 extend beyond a groove region 124 of the socket member 120 . This can facilitate securing the probe member within the groove region 124 of the socket member 120 . [0089] In an embodiment, an opening 126 of the socket member 120 can include an additional opening portion 128 to accommodate the insertion of the stem portion of the probe member 116 , having an increased size, therethrough. This can ensure proper alignment of the probe member with respect to the socket member before insertion of the probe member into the socket member thus facilitating the insertion process. [0090] It should be appreciated that the probe member, socket member and contact retainer member can be composed of a variety of different and suitable materials including, for example, plastics, molded plastics, like materials or combinations thereof. The various components of the coupling device, such as the probe member, socket member and contact retainer member, can be fitted in any suitable way. For example, the components can be fitted in smooth engagement (as shown in FIGS. 2A and 2B ), in threaded engagement (as shown in FIGS. 2D and 2E ) and/or any suitable fitting engagement or arrangement to one another. [0091] As shown in FIGS. 2D and 2E , the coupling device 130 of the present invention can be made of threaded parts which are removably connected to one another to form the coupling device. The threaded parts can facilitate securing the electrode to the blood circuit as well as general use of same as described below. [0092] In an embodiment, the stem portion 132 of the body 134 of the coupling device 130 has a threaded region 136 which can be insertably attached to a dialysis machine or other suitable mounting device in threaded engagement. This can facilitate the ease in which the coupling device is attached and detached from the mounting device. [0093] As shown in FIG. 2E , the stem portion 132 is threaded on both sides allowing it to be in threaded engagement with an annular member 138 . The annular member 138 provides direction and support allowing the electrical contact member 140 to abut against the electrode 142 housed in the probe member 144 as previously discussed. [0094] In an embodiment, a plate member 146 made of any suitable conductive material can be depressed against a spring 148 as the probe member 144 is secured to the body 134 . At the same time, another spring 150 can be displaced against the electrical contact member 140 in contact with the retainer 152 which is inserted within an annular region of the annular member 138 to secure the electrical contact member 140 to the body 134 . [0095] The spring mechanism in an embodiment of the present invention allows the parts of the coupling device 130 to remain in secure engagement during use. It can also facilitate use during detachment of the parts for cleaning, maintenance or other suitable purpose. [0096] In an embodiment, the coupling device can include a device with an electrical contact attached allowing the electrical contact to pierce or puncture the a fluid conduit when the device is movably attached to the fluid conduit. In this regard, the device can act through a clamping mechanism to allow electrical and fluid communication between the electrical contact and fluid flowing through the fluid conduit. The device can be coupled to a controller or the like allowing detection of access disconnection using direct conductive measurement during medical therapy, such as dialysis therapy, as previously discussed. The device can be made in a variety of suitable ways. [0097] In an embodiment, the device 153 includes a first member 154 and a second member 155 movably attached to the first member 154 at an end 156 as shown in FIG. 2F . The first and second members can be attached in any suitable way, such as by a hinge 157 or other suitable mechanism that can allow movement of the first and second members such that the device 153 can be attached to a fluid conduit. The movable members of the device 153 can be composed of any suitable material, preferably a conductive material, such as stainless steel, that is compatible with the electrical contact such that an effective electrical connection can be made. [0098] The electrical contact 158 can be composed of any suitable material, such as stainless steel, as previously discussed. The electrical contact material defines a shape and is attached to a portion of the first or second members in any suitable way. This allows the electrical contact 158 to puncture or pierce a fluid conduit when the device 158 is attached thereto such that the electrical contact 158 can make electrical and fluid contact with fluid flowing through the conduit. [0099] In an embodiment, the device 158 is self-sealing upon attachment to the fluid conduit. This can be done in any suitable way, such as by applying any suitable adhesive, gel or other sealing material to the device 158 , if necessary, prior to attachment to the fluid conduit. In this regard, the device 153 provides a simple design that can be effectively and readily used to provide both fluid and electrical contact between an electrical contact and fluid flowing through a fluid conduit, such as a blood circuit. [0100] As previously discussed, the present invention can be effectively utilized to detect dislodgment of an access device, such as a needle, inserted within a patient through which fluid can pass between the patient and a fluid delivery and/or treatment system. The present invention can be applied in a number of different applications, such as medical therapies or treatments, particularly dialysis therapies. In dialysis therapies, access devices, such as needles, are inserted into a patient's arteries and veins to connect blood flow to and from the dialysis machine. [0101] Under these circumstances, if the needle becomes dislodged or separated from the blood circuit, particularly the venous needle, the amount of blood loss from the patient can be significant and immediate. In this regard, the present invention can be utilized to controllably and effectively minimize blood loss from a patient due to dislodgment of the access device, such as during dialysis therapy including hemodialysis, hemofiltration, hemodiafiltration and continuous renal replacement. Signal Detection and Processing [0102] As previously discussed, the electrical contacts in connection with the controller can be used to detect a change in impedance or the like in response to needle drop-out or other like changes in access conditions. In an embodiment, the present invention can be adapted to correct for any variations in the baseline impedance over time. This can increase the level of sensitivity with respect to the detection capabilities of the present invention. In this regard, if changes in the baseline impedance are too great and not adequately corrected for, changes in impedance due to needle dislodgment may not be as readily, if at all, detectable above baseline values. [0103] From a practical standpoint, there are a number of different process conditions that may influence a change in the baseline impedance over time. For example, a gradual drift or change in the baseline can occur due to a change in the characteristics, such as the hematocrit, plasma protein, blood/water conductivity and/or the like, of the blood or other suitable fluid during treatment. This can arise due to changes in the level of electrolytes or other components during dialysis therapy. [0104] As illustrated in FIG. 3 , the present invention can process a measurable voltage signal to correct for changes in baseline impedance over time. This can enhance the detection capabilities of the present invention as previously discussed. In an embodiment, a current source 160 or the like generates an electric current to pass through the blood as it circulates into, through and out of the patient along the extracorporeal blood circuit 162 which connects the patient via venous and arterial needles to the dialysis system including a variety of process components. The electric current is injected into the blood circuit via a first electrical contact 163 a thereby defining a conductor loop or pathway along the blood circuits. Preferably, the current is maintained at a constant level until dislodgment occurs. The second electrode 163 b is used to sense voltage or the like along the conductor loop and then pass a signal indicative of same and/or changes thereof to an electronic device for detection and processing as previously discussed. The voltage signal can be measured and processed in any suitable manner. [0105] In an embodiment, the signal is passed through a series of components including a filter or filters 164 which can act to filter noise from the signal, particularly noise derived from the rotation from the pump in order to minimize a false negative and/or positive detection of needle dislodgment, a rectifier 166 , a peak detector 168 and an analog to digital converter (“ADC”) 170 to digitize the signal. In this regard, the digital signal can then be stored in a computer device (not shown) for further processing. The voltage signal is continually measured and processed over time. With each measurement, the digitized signals are compared to evaluate changes due to baseline changes associated with variations in process conditions over time, such as a change in the characteristics of blood as previously discussed. If a baseline change is determined, the digitized signal can be further processed to correct for the change in baseline. [0106] The voltage data is continually sent to a control unit 172 coupled to the ADC. The control unit continually performs a calculation to determine whether a change in impedance or the like in response to needle dislodgment has occurred. In an embodiment, dislodgment of an access device is detected when [V(t)−V(t−T)]>C1, where t is time, where T is the period of blood pump revolution, where C1 is a constant and where V(t)=Io*Z, where Io is current and where Z is the impedance of the bloodline which is a function of the impedance associated with patient's vascular access and the impedance associated with various components of the dialysis system, such as the dialyzer, as previously discussed. [0107] If disconnection of the patient from the blood circuit is detected, the control unit 172 can be utilized to process the signal in order to minimize blood loss from the patient. In an embodiment, the controller is in communication with a dialysis system as applied to administer dialysis therapy including, for example, hemodialysis, hemofiltration, hemodiafiltration and continuous renal replacement. This communication can be either hard-wired (i.e., electrical communication cable), a wireless communication (i.e., wireless RF interface), a pneumatic interface or the like. In this regard, the controller can process the signal to communicate with the dialysis system or device to shut off or stop the blood pump 174 associated with the hemodialysis machine and thus effectively minimize the amount of blood loss from the patient due to needle dislodgment during hemodialysis. [0108] The controller can communicate with the dialysis system in a variety of other ways. For example, the controller and hemodialysis machine can communicate to activate a venous line clamp 176 for preventing further blood flow via the venous needle thus minimizing blood loss to the patient. In an embodiment, the venous line clamp is activated by the controller and attached to or positioned relative to the venous needle such that it can clamp off the venous line in close proximity to the needle. Once clamped, the dialysis system is capable of sensing an increase in pressure and can be programmed to shut-off the blood pump upon sensing pressure within the blood flow line which is above a predetermined level. Alternatively, the venous line clamp can be controllably attached to the dialysis system. [0109] In an embodiment, an alarm can be activated upon detection of blood loss due to, for example, needle dislodgment during dialysis therapy. Once activated, the alarm (i.e., audio and/or visual or the like) is capable of alerting the patient, a medical care provider (i.e., doctor, registered nurse or the like) and/or a non-medical care provider (i.e., family member, friend or the like) of the blood loss due to, for example, needle dislodgment. The alarm function is particularly desirable during dialysis therapy in a non-medical facility, such as in a home setting or self care setting where dialysis therapy is typically administered by the patient and/or a non-medical care provider in a non-medical setting or environment excluding a hospital or other like medical facility. [0110] In this regard, the alarm activation allows, for example, the patient to responsively act to ensure that the dialysis therapy is terminated by, for example, to check that the blood pump has been automatically shut off to minimize blood loss to the patient. Thus, the patient has the ability to act without the assistance of a third party (i.e., to act on his or her own) to ensure that responsive measures are taken to minimize blood loss. The alarm can thus function to ensure the patient's safety during the administration of dialysis therapy, particularly as applied to home hemo treatments where at least a portion of the dialysis therapy can be administered while the patient is sleeping. Dialysis Machine [0111] As previously discussed, the present invention can be adapted for use with any suitable fluid delivery system, treatment system or the like. In an embodiment, the present invention is adapted for use with a dialysis machine to detect access disconnection as blood flows between the patient and the dialysis machine along a blood circuit during treatment, including, for example hemodialysis, hemofiltration and hemodiafiltration. [0112] The present invention can include any suitable dialysis machine for such purposes. An example, of a hemodialysis machine of the present invention is disclosed in U.S. Pat. No. 6,143,181 herein incorporated by reference. In an embodiment, the dialysis machine 190 comprises a mobile chassis 192 and it has at the front side 194 thereof with a common mechanism 196 for connecting tubing or the like by which a patient can be connected to the dialysis machine as shown in FIG. 4A . A flat touch screen 197 which can show several operational parameters and is provided with symbols and fields for adjustment of the dialysis machine by relevant symbols and fields, respectively, on the screen being touched can be adjusted vertically and can be universally pivoted on the dialysis machine and can be fixed in the desired adjusted position. [0113] In an embodiment, the dialysis machine includes a chassis having one or more connectors for connecting a patient to the dialysis machine via a blood circuit allowing blood to flow between the patient and the dialysis machine during dialysis therapy wherein one or more electrical contacts are connected to the blood circuit in fluid communication with the blood allowing detection of a change in an electrical value in response to access disconnection as the blood flows through the blood circuit having an electrical signal passing therein. [0114] In an embodiment, the dialysis machine of the present invention can be designed to accommodate one or more of the electrical contact coupling devices, such as a pair of coupling device, used to detect access disconnection as shown in FIG. 4B . For example, one or more coupling devices 198 can be attached to the front panel 194 of the dialysis machine 190 . This can be done in any suitable way. In an embodiment, the a stem portion of the coupling device is insertably mounted via a threaded fit, frictional fit or the like, as previously discussed. This connects the patient to the dialysis machine 190 via a blood tubing set 202 . The blood tubing set includes a first blood line 204 and a second blood line 206 . In an embodiment, the first blood line 204 is connected to the patient via an arterial needle 208 or the like through which blood can flow from the patient 200 to the dialysis machine 190 . The second blood line 206 is then connected to the patient 200 via a venous needle 210 or the like through which fluid flows from the dialysis machine to the patient thereby defining a blood circuit. Alternatively, the first blood line and the second blood line can be coupled to the venous needle and the arterial needle, respectively. The blood lines are made from any suitable medical grade material. In this regard, access disconnection, such as dislodgment of an arterial needle and/or a venous needle can be detected as previously discussed. Alternatively, the coupling device can be attached to the blood tubing set which is then attached to the dialysis machine in any suitable way. Dialysis Treatment Centers [0115] As previously discussed, the present invention can be used during dialysis therapy conducted at home and in dialysis treatment centers. The dialysis treatment centers can provide dialysis therapy to a number of patients. In this regard, the treatment centers include a number of dialysis machines to accommodate patient demands. The therapy sessions at dialysis treatment centers can be performed 24 hours a day, seven days a week depending on the locale and the patient demand for use. [0116] In an embodiment, the dialysis treatment centers are provided with the capability to detect access disconnection during dialysis therapy pursuant to an embodiment of the present invention. For example, one or more of the dialysis machines can be adapted for use with an electrical contact coupling device along with the necessary other components to detect access disconnection as previously discussed. [0117] In an embodiment, the electrical contact coupling device can be directly attached to one or more of the dialysis machines of the dialysis treatment center. It should be appreciated that the apparatuses, devices, methods and/or systems pursuant to an embodiment of the present invention can be applied for use during dialysis therapy administered to one or more patients in the dialysis treatment center in any suitable way. In an embodiment, the treatment center can have one or more patient stations at which dialysis therapy can be performed on one or more patients each coupled to a respective dialysis machine. Any suitable in-center therapy can be performed including, for example, hemodialysis, hemofiltration and hemodiafiltration and combinations thereof. As used herein, the term “patient station” or other like terms mean any suitably defined area of the dialysis treatment center dedicated for use during dialysis therapy. The patient station can include any number and type of suitable equipment necessary to administer dialysis therapy. [0118] In an embodiment, the dialysis treatment center includes a number of patient stations each at which dialysis therapy can be administered to one or more patients; and one or more dialysis machines located at a respective patient station. One or more of the dialysis machines can include a chassis having one or more connectors for connecting a patient to the dialysis machine via a blood circuit allowing blood to flow between the patient and the dialysis machine during dialysis therapy wherein a pair of electrical contacts are connected to the blood circuit in fluid communication with the blood allowing detection of a change in an electrical value in response to access disconnection as the blood flows through the blood circuit having an electrical signal passing therein. [0119] As previously discussed, the access disconnection detection capabilities of the present invention can be utilized to monitor and control a safe and effective dialysis therapy. Upon dislodgment of an access device, such as a needle, from the patient, the direct conductive measurement capabilities of the present invention can be used to provide a signal indicative of dislodgment that can be further processed for control and/or monitoring purposes. In an embodiment, the signal can be further processed to automatically terminate dialysis therapy to minimize blood loss due to dislodgment as previously discussed. Further, the signal can be processed to activate an alarm which can alert the patient and/or medical personnel to the dislodgment condition to ensure that responsive measures are taken. It should be appreciated that the present invention can be modified in a variety of suitable ways to facilitate the safe and effective administration of medical therapy, including dialysis therapy. [0120] Applicants have found that the direct conductive measurement capabilities of the apparatus of the present invention can immediately detect blood loss or the like due to access disconnection, such as needle dislodgment, with high sensitivity and selectivity such that responsive measures can be taken to minimize blood loss due to same. The ability to act responsively and quickly to minimize blood loss upon detection thereof is particularly important with respect to needle dislodgment during hemodialysis. If not detected and responded to immediately, the amount of blood loss can be significant. In an embodiment, the present invention is capable of taking active or responsive measures, to minimize blood loss (i.e., shut-off blood pump, activate venous line clamp or the like) within about three seconds or less, preferably within about two to about three second upon immediate detection of needle dislodgment. [0121] In addition, the controller can be utilized to monitor and/or control one or more treatment parameters during hemodialysis. These parameters can include, for example, the detection of blood due to blood loss upon needle dislodgment, the change in blood flow, the detection of air bubbles in the arterial line, detection of movement of the sensor during treatment, detection and/or monitoring of electrical continuity of the sensor or other like treatment parameters. In an embodiment, the controller includes a display (not shown) for monitoring one or more of the parameters. [0122] As used herein “medical care provider” or other like terms including, for example, “medical care personnel”, means an individual or individuals who are medically licensed, trained, experienced and/or otherwise qualified to practice and/or administer medical procedures including, for example, dialysis therapy, to a patient. Examples of a medical care provider include a doctor, a physician, a registered nurse or other like medical care personnel. [0123] As used herein “non-medical care provider” or other like terms including, for example, “non-medical care personnel” means an individual or individuals who are not generally recognized as typical medical care providers, such as doctors, physicians, registered nurses or the like. Examples of non-medical care providers include patients, family members, friends or other like individuals. [0124] As used herein “medical facility” or other like terms including, for example, “medical setting” means a facility or center where medical procedures or therapies, including dialysis therapies, are typically performed under the care of medical care personnel. Examples of medical facilities include hospitals, medical treatment facilities, such as dialysis treatment facilities, dialysis treatment centers, hemodialysis centers or the like. [0125] As used herein “non-medical facility” or other like terms including, for example, “non-medical setting” means a facility, center, setting and/or environment that is not recognized as a typical medical facility, such as a hospital or the like. Examples of non-medical settings include a home, a residence or the like. [0126] It should be appreciated that the electrode output signal can be combined with other less sensitive blood loss detection methods, such as venous pressure measurements, systemic blood pressure, the like or combinations thereof, to improve specificity to needle dislodgment. [0127] It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.

An access disconnection method for a machine employing a blood circuit, the blood circuit having a machine segment and a patient access segment, the method comprising: injecting an electrical signal into the blood circuit between the machine segment and the patient access segment; attempting to cause the electrical signal to flow through only the patient access segment and to bypass the machine segment; and measuring the signal in the patient access segment and determining that an access disconnection event has occurred upon a threshold change in the measured signal.

STATEMENT OF GOVERNMENT INTEREST [0001] The United States Government claims certain rights pursuant to Contract No. W-31-109-ENG-38 between the United States Government and the University of Chicago and/or pursuant to DE-AC02-06CH11357 between the United States Government and UChicago Argonne, LLC representing Argonne National Laboratory. FIELD [0002] The technology is generally related to lithium ion batteries. More specifically, it is related to nanocomposite materials that can be used as anode materials for lithium ion batteries. BACKGROUND [0003] The use of Li-ion batteries (LIBs) as rechargeable power sources represents a promising technology for use in consumer electronics and automobiles. However, there are substantial technical challenges to the use of LIBs for automobile applications. [0004] LIBs typically use lithium metal oxides such as LiCoO 2 as the cathode; carbon or graphite as the anode; and a lithium salt such as LiPF 6 in an organic solvent (e.g., organic carbonates) as the electrolyte. Since its commercialization, the capacity of LIBs has increased about 1.7 times due to improvements in battery structure, and anode or cathode materials. The capacity of the LIBs has been improved typically by increasing the amount of the active materials in the cathode, and anode, and by decreasing the thickness of the current collector, separator, and cell casing. For example, LIB capacity has improved by utilizing new cathode materials, such as layered Li[Ni x CO y Mn z ]O 2 and related materials. Use of such new materials has provided about 9 to about 25% increase in the total mAh/g capacity over commercial cells; but this is still insufficient to satisfy the requirements of plug-in hybrid electric vehicles (PHEVs) or electric vehicles (EVs). [0005] In addition to cathode materials, improved anode materials have also been investigated. Anode materials for LIBs typically fall into one of two types of materials: intercalation materials and alloy-forming materials. Graphite falls in the first category and allows intercalation of Li ions into its carbon layers for storage of lithium. Graphite exhibits good charge/discharge cycle stability, but low capacity. The theoretical capacity of graphite is 372 mAh/g based on a theoretical Li-to-C ratio (Li:C) of about 1:6 (i.e., LiC 6 ). [0006] Alloy-forming materials include, but are not limited to, Si, Sn, Pb, Al, Au, Pt, Zn, Cd, Ag, and Mg, can be used as alternatives to graphite. These materials store Li by forming alloys with Li. Si is one of the most attractive because of its relatively low discharge potential, the theoretical capacity (about 4200 mAh/g based on Li 4.4 S) and significant natural reserve (Si is the second most abundant element on earth). The disadvantage of alloy-forming materials such as Si is that the capacity fades rapidly due to very large volume expansions upon alloy formation. The large expansion and following contraction can cause disruption (e.g., pulverization) of the electrode and loss of electric contact between electrode materials limiting the cycle stability of these anode materials. For example, Si may undergo up to 400% volume change during the alloying and de-alloying process. Bulk Si is also not desirable as anode material because of a relatively low electrical conductivity, which can reduce the capacity of the LIBs. [0007] Further improvement of LIBs require the development of new anode materials with desired properties. SUMMARY [0008] According to one aspect, a process is provided which includes contacting a gaseous electroactive material precursor with a carbonaceous, exfoliated nanosheet material to form a nanocomposite material. The carbonaceous, exfoliated nanosheet material has a plurality of layers. The nanocomposite material has an electroactive material is intercalated between individual layers of the plurality of layers; an electroactive material is deposited on one or more surfaces of the individual layers of the plurality of layers; or an electroactive material is both intercalated between individual layers of the plurality of layers and deposited on one or more surfaces of the individual layers of the plurality of layers. In some embodiments, the carbonaceous, exfoliated nanosheet material is graphene. [0009] In some embodiments, the electroactive material includes Si, Sn, Pb, Al, Au, Pt, Zn, Cd, Ag, Mg, or Mo. In some embodiments, the electroactive material includes an oxide of Si, Sn, Pb, Al, Au, Pt, Zn, Cd, Ag, Mg or Mo. In some embodiments, the electroactive material includes Si or Sn. In some embodiments, the electroactive material is not the same as the layered nanosheet material. [0010] In some embodiments, contacting the gaseous electroactive material precursor with the carbonaceous, exfoliated nanosheet material includes depositing the gaseous electroactive material precursor by using chemical vapor deposition. In some embodiments, the contacting includes depositing the gaseous electroactive material precursor using a fluidized bed chemical vapor deposition process. In some embodiments, the chemical vapor deposition includes pyrolytic or plasma-assisted deposition. In some embodiments, the electroactive material precursor is in the vapor phase prior to deposition, while in other embodiments, the electroactive material is in the liquid phase prior to deposition. In some embodiments, the gaseous electroactive material precursor includes one or more silicon-containing compounds, or one or more tin-containing compounds. In some embodiments, the electroactive material precursor includes a silicon-containing compound such as, but not limited to, silane, silicon tetrachloride, trichlorosilane, trichloromethylsilane, dichlorosilane, dichloromethylsilane, dichlorodimethylsilane, chlorotrimethylsilane, chlorosilane, chloromethylsilane, chlorodimethylsilane, phenylsilane, tetramethoxysilane, tetraethoxysilane, cyclopropylsilane, cyclobutylsilane, cyclopentylsilane, cyclohexylsilane, cyclooctylsilane, diphenylsilane, dicyclohexylsilane, n-butylmethylsilane, tert-butylmethylsilane, or tert-butylphenylsilane. In some embodiments, the electroactive material precursor includes a tin-containing compound such as, but not limited to, monobutyltin trichloride, methyltin trichloride isobutyltin trichloride, butyl dichlorotin acetate, butyldichlorotin dicetate, diisobutyltin dichloride, methyltin trichloride, dimethyltin dichloride, dibutyltin dichloride di-t-butyltin dichloride, or tin tetrachoride. [0011] In some embodiments, the carbonaceous, exfoliated nanosheet material includes a dopant. Such dopants may include, but are not limited to N, S, or O. In some embodiments, the process further includes heating the nanocomposite material to a temperature between 500° C. to 1500° C. In some embodiments, the heating is conducted in the presence of a reactive gas. In some embodiments, the reactive gas includes hydrogen, ammonia, a phosphorus-containing gas, or a boron-containing gas. [0012] In another aspect, a material is provided that is prepared by any of the described processes. In another aspect, an electrochemical device is provided, the device including any such materials. In some embodiments, the electrochemical device includes an anode including the material. In some embodiments, the electrochemical device is a lithium primary battery, a lithium secondary battery, a capacitor or a lithium air battery. [0013] In another aspect, a process is provided that includes providing graphene where the graphene has a plurality of layers in a layered nanosheet structure, and introducing to the graphene an electroactive material precursor with Si or Sn to produce a nanocomposite material. The nanocomposite material includes an electroactive material that is intercalated between individual layers of the plurality of layers; deposited on one or more surfaces of the individual layers of the plurality of layers; or is both intercalated between individual layers of the plurality of layers and deposited on one or more surfaces of the individual layers of the plurality of layers. BRIEF DESCRIPTION OF THE DRAWINGS [0014] FIGS. lA and 1 B are schematic illustrations of a layered material having an electroactive material deposited between (1A) or on (1B) the individual layers, according to some embodiments. [0015] FIG. 2 is a dual axis graph of the capacity (left) and the efficiency (right) v. cycle number for a silicon-graphene nanocomposite material prepared according to the examples. [0016] FIG. 3 is a graph of capacity v. number of cycles of a silicon-graphene nanocomposite material prepared according to the Example 6, as compared to a bulk silicon material used as the anode in a coin cell battery. [0017] FIGS. 4 A and 4 B are graphs of the voltage v. capacity during the first charge and discharge of a reduced silicon-graphene nanocomposite material, prepared according to Example 7. [0018] FIG. 5 is a graph of capacity v. number of cycles of the silicon-graphene nanocomposite material prepared according to the Example 7. DETAILED DESCRIPTION [0019] The illustrative embodiments described in the detailed description are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here. [0020] As used herein, “about” will be understood by persons of ordinary skill in the art and will vary to some extent depending upon the context in which it is used. If there are uses of the term which are not clear to persons of ordinary skill in the art, given the context in which it is used, “about” will mean up to plus or minus 10% of the particular term. [0021] As used herein, “graphene” refers to planar sheets of sp 2 -bonded carbon atoms that are densely packed in a honeycomb crystal lattice. It can be viewed as an atomic-scale, layered, chicken wire made of carbon atoms and their bonds. [0022] As used herein, “carbonaceous” refers to a material rich in carbon. [0023] As used herein, “nanosheet material” refers to a material containing sheets or layers with a thickness from a few nanometers to about two hundred nanometers. The nanosheet material serves as support material for the electroactive material, and provides dimensional stability for the lithium alloy formed during the lithiation and delithiation process, as well as establishing an electronic conducting pathway within the electrode. [0024] In one aspect, a process is provided for incorporating electroactive materials within a nanosheet material to produce nanocomposite materials. Such materials may be used in a wide variety of applications including, but not limited to battery applications. The nanosheet materials are those which are carbonaceous, and which have an exfoliated nanosheet structure with a plurality of layers. As used herein the term exfoliated refers to expansion of the layered structure to allow for interaction of other species within the layers. [0025] In some embodiments, the nanosheet materials are pretreated by thermal shock done under an inert gas such as nitrogen, helium, or argon. The presence of the inert gas reduces the occurrence of oxidation of the nanosheet material, thereby maintaining the conductivity of the graphene. The thermal shock treatment expands the natural graphite to graphene. [0026] In other embodiments, the composite material is prepared by using a natural graphite intercalation compound (GIC). Natural graphite is subjected to an intercalation/oxidation treatment by immersing graphite powder in a solution of sulfuric acid, nitric acid, and potassium permanganate for between 1 to 24 hours. The powder is then isolated from the acids and dried. The dried powder is then subjected to thermal shock (e.g., 1,000° C. for 15-30 seconds) to obtain exfoliated graphite worms, which are networks of interconnected exfoliated graphite flakes with each flake containing a multiplicity of, graphene sheets or layers. The exfoliated graphite is then subjected to mechanical shearing to break up the graphite flakes and produce graphene. The mechanical shearing may be accomplished using any of a variety of techniques including, but not limited to, air milling, ball milling, or ultrasonication. After the pre-treatment, the nanosheet may be further treated to form nanocomposite materials. [0027] FIGS. 1A and 1B are schematic illustrations of the nanocomposite material having particulate or film electroactive materials. FIG. lA illustrates the case where layers 101 of the nanocomposite material are intercalated with particles of the electroactive material 102 . In FIG. 1B , the nanocomposite layers 101 have a film or coating of the electroactive material 103 between the layers. [0028] As illustrated in FIGS. 1A and 1B , the nanocomposite material includes the electroactive material either between, or on, individual layers of the nanosheet host as a particle, or as a film that is between, or on, individual layers of the nanosheet host. Thus, in some embodiments, the electroactive material is intercalated between individual layers of the plurality of layers; the electroactive material is deposited on one or more surfaces of the individual layers of the plurality of layers; or the electroactive material is both intercalated between individual layers of the plurality of layers and deposited on one or more surfaces of the individual layers of the plurality of layers. The nanocomposite material is formed when a gaseous electroactive material precursor is contacted with the carbonaceous, exfoliated nanosheet material and the precursor then is converted into the electroactive material. According to some embodiments, converting the precursor to the electroactive material includes pyrolysis. [0029] Suitable nanosheet materials are carbonaceous substances that include, but are not limited to, graphene, graphite, carbon nanotubes, carbon fiber, activated carbon, porous carbon, and glassy carbon. In some embodiments, the nanosheet material is graphene. Graphene is suitable because it has a high surface area, good electric conductivity, and good electrochemical stability. Graphene consists of a two-dimensional (2D) sheet of covalently bonded carbon atoms and it forms the basis of both 3D graphite and 1D carbon nanotubes. Graphene has a thermal conductivity of up to ˜5,300 W/mK, and it exhibits exceptional in-plane electrical conductivity (up to ˜20,000 S/cm), an ultra-high Young's modulus (approximately 1,000 GPa), and high intrinsic strength (˜130 GPa, estimated). In some embodiments, the nanosheet material is graphene. In some embodiments, the nanosheet material is graphite. [0030] As noted above, the nanosheet material is exfoliated, thereby exposing several individual sheets (i.e. individual layers). The nanosheets have dimensions which are on the nanometer (nm) scale in thickness, and one the micrometer (μm) in the planar dimensions. For example, a single nanosheet of the material may have a length of no more than about 60 μm and a length of no more than about 60 μm. In some embodiments, the nanosheet has length of about 50 nm to about 20 μm, and individually a length of about 50 nm to about 20 μm. A single nanosheet of the material may have a thickness of about 0.1 nm to about 1 nm. In some embodiments, a single layer or sheet of the nanosheet material is about 0.335 nm thick. The bulk nanosheet material may include a plurality of nanosheets, wherein the plurality of nanosheets has a stack thickness of up to about 200 nm. In some embodiments, the thickness of stack of the layers is from about 0.67 nm to about 100 nm. [0031] Electroactive materials suitable for use in the methods include many known electroactive materials, particularly elements of Groups III, IV and V of the periodic table. Such electroactive materials are capable of lithiation and de-lithiation by formation of alloys and desorption of the Li. These elements may be alloyed or mixed with other metals. In some embodiments, the electroactive material includes Si, Sn, Pb, Al, Au, Pt, Zn, Cd, Ag, Mg, Mo or mixtures thereof. In some embodiments, the electroactive material includes an oxide of Si, Sn, Pb, Al, Au, Pt, Zn, Cd, Ag, Mg, Mo or mixtures thereof. In some embodiments, the electroactive material may be a mixture of a metal and a metal oxide. In some embodiments, the electroactive material is Si or Sn. The Si may be crystalline Si, amorphous Si, or Si compounds such as silicon carbide and silicon oxide, or mixtures thereof [0032] In some embodiments, the electroactive material is substantially homogenously intercalated within the plurality of layers. The process provided for preparing nanocomposite materials is in contrast to the previously used physical mixing approaches. It is difficult to achieve nanoscale deposition of Si inside the graphene layers through physical mixing approaches alone, due to the agglomeration of Si nanoparticles and high surface tension in liquid phase. As a result, nanocomposite materials prepared by physical mixing have agglomerated electroactive materials along the edges of the layered material, instead of homogenously distributed within the interior of the layered material. Although these materials can achieve some limited capacity, such as 1000 mAh/g, the capacity degradation of such anodes is large with a loss of 51% of the capacity after 300 cycles as seen in Lee, et al., Chem. Communications, 46(12): 2025-2027. In contrast, the Si-Graphene composite materials exhibit a substantially smaller loss in reversible capacity. This is further illustrated in the examples. [0033] The electroactive material may be formed as particle or film on the surface of the nanosheet material or as a particle or film between the layers. In some embodiments, the electroactive material may be present as particles intercalated between the layers of the nanosheet, particles incorporated into a single layer of the sheet, or deposited on the surface of the nanosheet material. In some embodiments, the electroactive material may be present as both a film and as a particle. Where the electroactive material is present as a particle, the particles may have a diameter from about 2 nm to about 2 μm, or from 100 nm to 1 μm. [0034] The electroactive material is formed by decomposition of a gaseous electroactive material precursor, during, or after, impregnation of the exfoliated nanosheet material. This allows the gaseous precursor to penetrate the individual layers more fully than if liquid or solid phase techniques were used. The precursor may include one or more silicon-containing compounds, or one or more tin-containing compounds. Suitable electroactive material precursors include silicon-containing compounds such as, but not limited to, silane, silicon tetrachloride, trichlorosilane, trichloromethylsilane, dichlorosilane, dichloromethylsilane, dichlorodimethylsilane, chlorotrimethylsilane, chlorosilane, chloromethylsilane, chlorodimethylsilane, phenylsilane, tetramethoxysilane, tetraethoxysilane, cyclopropylsilane, cyclobutylsilane, cyclopentylsilane, cyclohexylsilane, cyclooctylsilane, diphenylsilane, dicyclohexylsilane, n-butylmethylsilane, tert-butylmethylsilane, or tert-butylphenylsilane. In some embodiments, the electroactive material precursor includes a tin-containing compound such as, but not limited to, monobutyltin trichloride, methyltin trichloride isobutyltin trichloride, butyl dichlorotin acetate, butyldichlorotin dicetate, diisobutyltin dichloride, methyltin trichloride, dimethyltin dichloride, dibutyltin dichloride di-t-butyltin dichloride, or tin tetrachloride. [0035] The electroactive materials may be deposited on the surface of the nanosheet material by a variety of different methods. For example, such methods include, among others, liquid-phase deposition, electrodeposition, dip-coating, evaporation, sputtering, and chemical vapor deposition (CVD). [0036] In some embodiments, the composite material is prepared by CVD. Such methods include, contacting a gaseous electroactive material precursor with a carbonaceous, exfoliated nanosheet material. In a typical CVD process, the substrate or host is exposed to one or more volatile CVD precursors, which react and decompose on the substrate surface to produce a deposit. CVD is one of the most efficient techniques for modification and control of the surface state of powders. The use of gases allows for formation of cluster distributions on all porous surfaces, and, thus, achieves nano-scale homogenous distribution of the electroactive materials within the layers or sheets of the nanosheet material. [0037] In one illustrative example, gaseous silane (SiH 4 ) is contacted with the nanosheet material host at 600° C. to give a uniform deposition of Si on or in between layers or sheets of the graphene according to the following reaction scheme: [0000] SiH 4 →Si+2H 2 [0038] As another illustrative example, the Si is deposited using a gas feed containing a mixture of hydrogen and trichlorosilane in a fluidized bed reactor containing the nanosheet materials at high temperature. Decomposition of the trichlorosilane causes the deposition of elemental Si on the surface or between the layers or sheets of the graphene nanosheets according to the following reaction scheme: [0000] HSiC 1 3 ( g )+H 2 ( g )=Si( s )+3HCl( g ) [0000] Fluidized bed reactors allow for a large contact area between the graphene and the silicon-bearing gases in a heated chamber, enhancing the thermal decomposition of the silicon-bearing gases. Upon decomposition of the gases, high-purity, elemental Si coatings or deposits on the surface of the graphene layers, or Si-intercalated within the layers of the nanocomposite material are formed [0039] In some embodiments, the nanocomposite material is a Si-Graphene nanocomposite. Strong bonding between the Si and graphene material helps stabilize the nanocomposite material during lithiation and delithiation cycles. The mesoporous structure of the graphene nanosheet and outstanding elastic deformability serves as a buffer layer allowing for the large volume expansion exhibited by the Si when it is alloyed with Li. During delithiation, the graphene is able to regain its original structure with minimal irreversible damage. In addition, when the Si-graphene nanocomposite is used as an anode in an electrochemical cell, the problem of delamination is minimized because the nanosheet structure of the graphene has many voids into which the Si can expand without being in physical contact with the current collector. Thus, the nanocomposites avoid the delamination associated with other systems. [0040] In the Si-Graphene composite, the presence of the graphene improves the cycling performance of the nanocomposite materials by increasing the electrical conductivity and acting as an electrochemical buffer, thereby reducing electrochemical sintering or coalescence of the fine Si particles. Further, when the amount of graphene in the nanocomposite material reaches a certain threshold volume fraction (percolation condition), graphene may form a continuous path for electrons, thereby improving electrical conductivity significantly. Although not bound by theory, the inventors consider the Si-graphene composites to be a double-phased material where both phases, the graphene and the Si, are active toward Li within the same potential window. Si-graphene composite materials can achieve fast charge and discharge rates because of their high surface area (200 m 2 /g to 1000 m 2 /g), their mesoporosity, and their relatively high electronic conductivity. The charge discharge rate can be in the range of C/3 to 3C, which is sufficiently fast for PHEV and EV applications. [0041] In some embodiments, the graphene is doped with a heteroatom to enhance the cycle stability of the electroactive materials. Suitable heteroatoms include, but are not limited to, N, S, and O. Although not to be bound by theory, it is understood that incorporation of N, S, and O creates defects on the graphene layers, which facilitate the initial nucleation of silicon seeds on the graphene layers. More silicon seeds mean more uniform and smaller silicon particles on graphene layers at a given silicon loading. Smaller silicon particles lead to improved cycle stability. [0042] Optionally, nanocomposite materials produced by the processes may be heat-treated in the presence of a reactive gas. Where heat treatment is used, the nanocomposite materials are heated to from 500° C. to 1500° C. The reactive gas in such methods may be hydrogen, ammonia, a phosphorus containing gas, a boron-containing gas or a mixture of any two or more of such gases. Under these conditions, oxygen-containing functional groups which may be present on the surface of the Si-Graphene composite material are reduced. Such oxygen-containing groups may be present due to the conditions and reactions used to prepare an exfoliated graphene, and may include lactone, ketone, phenol, ether, carboxyl, anhydride, and the like. Such treatments may also improve the first cycle efficiency, reversible capacity and/or cycle stability performance of the nanocomposite material. Although not bound by theory, it is believed that the heat treatment causes a phase-change within the composite material such that hydrogenated Si under low temperature is converted to polycrystalline Si with higher capacity. In addition, the high temperature treatment is believed to cause densification of the nanocomposite material. The increase in density of the nanocomposite may improve the contact between the graphene and Si, thereby improving stability. Accordingly, heat treatment may increase the density of the nanocomposite from about 10% to about 50%, in some embodiments. In other embodiments, the density increases from about 15% to about 40%, or from about 20% to about 30%. [0043] As indicated in the previous paragraph, heat treatments improve the first cycle efficiency. It is believed that the irreversible capacity loss during the first discharge and first charge of a battery is due to the formation of a passivating film or solid electrolyte interface (SEI) on the anode. This process consumes Li and electrolyte. Thus, improving the first cycle efficiency is important for improving the performance of anode materials. The heat treatments reduce the available materials for SEI or film formation, thereby reducing their deleterious effects. [0044] In some embodiments, the nanocomposite materials may be used to prepare electrodes. The nanocomposite can be made into a slurry using acetylene black and polyimide binders solvents such as N-methylpyrrolidone (NMP) and water. The slurry is then cast and the solvent removed by drying under nitrogen. This process leads to a highly conductive electrode that results improved performance in the coin cell. [0045] In another aspect, an electrochemical device is provided including an anode that includes the nanocomposite material, a cathode, and an electrolyte. Such devices include a lithium primary battery, a lithium secondary battery, a capacitor or a lithium air battery. [0046] In some embodiments, the cathode may be an air electrode, or include materials such as spinels, olivines with formula LiM a M′ b PO4 (where M and M′ are a transition metal), LiCoPO 4 , LiFePO 4 , LiNiPO 4 , LiCoO 2 , LiNiO 2 , LiNi 1−x Co y Met z O 2 , LiMn 0.5 Ni 0.5 O 2 , LiMn 0.3 Co 0.3 Ni 0.3 O 2 , LiMn 2 O 4 , LiFeO 2 , LiMet 0.5 Mn 1.5 O 4 , LiMet 0.5 Mn 1.5 O 4 , Li 1+x , Ni α Mn β Co γ Met′ δ O 2−z′ F z′ , A n ′B 2 (XO 4 ) 3 (Nasicon), vanadium oxide, or mixtures of any two or more such materials, where Met is Al, Mg, Ti, B, Ga, Si, Mn, or Co; Met′ is Mg, Zn, Al, Ga, B, Zr, or Ti; A is Li, Ag, Cu, Na, Mn, Fe, Co, Ni, Cu, or Zn; B is Ti, V, Cr, Fe, or Zr; X is P, S, Si, W, or Mo; 0≦x≦0.3, 0≦y≦0.5, 0≦z≦0.5; 0≦x′≦0.4, 0≦α≦1, 0≦β≦1, 0≦γ≦1, 0≦δ≦0.4, and 0≦z′≦0.4; and 0≦n′≦3. [0047] A variety of solvents may be employed in the electrolyte as the polar aprotic solvent. Suitable polar aprotic solvents include liquids and gels capable of solubilizing sufficient quantities of the lithium salt and the redox shuttle so that a suitable quantity of charge can be transported from the positive electrode to negative electrode. The solvents can be used over a wide temperature range, e.g., from −30° C. to 70° C. without freezing or boiling, and are stable in the electrochemical range within which the cell electrodes and shuttle operate. Suitable solvents include dimethyl carbonate; ethyl methyl carbonate; diethyl carbonate; methyl propyl carbonate; ethyl propyl carbonate; dipropyl carbonate; bis(trifluoroethyl) carbonate; bis(pentafluoropropyl) carbonate; trifluoroethyl methyl carbonate; pentafluoroethyl methyl carbonate; heptafluoropropyl methyl carbonate; perfluorobutyl methyl carbonate; trifluoroethyl ethyl carbonate; pentafluoroethyl ethyl carbonate; heptafluoropropyl ethyl carbonate; perfluorobutyl ethyl carbonate; fluorinated oligomers; dimethoxyethane; triglyme; dimethylvinylene carbonate; tetraethyleneglycol; dimethyl ether; polyethylene glycols; sulfones; and γ-butyrolactone. [0048] Suitable electrolyte salts include alkali metal salts, alkaline earth salts, and ammonium salts. In some embodiments, the salts are alkali metal salts such as lithium salts, sodium salts, or potassium salts. In one embodiment, the salt is a lithium salt that may include, but is not limited to, Li[B(C 2 O 4 ) 2 ]; Li[BF 2 (C 2 O 4 )]; LiC 1 O 4 ; LiBF 4 ; LiAsF 6 ; LiSbF 6 ; LiBr, LiPF 6 ; Li[CF 3 SO 3 ]; Li[N(CF 3 SO 2 ) 2 ]; Li[C(CF 3 SO 2 ) 3 ]; Li[B(C 6 F 5 ) 4 ]; Li[B(C 6 H 5 ) 4 ]; Li[N(SO 2 CF 3 ) 2 ];e Li[N(SO 2 CF 2 CF 3 ) 2 ]; LiN(SO 2 C 2 F 5 ) 2 ; Li[BF 3 C 2 F 5 ]; Li[PF 3 (CF 2 CF 3 ) 3 ]; or an lithium alkyl fluorophosphates. [0049] The above description will be understood more readily by reference to the following examples, which are provided by way of illustration and are not intended to be limiting to any particular embodiment. EXAMPLES Example 1 [0050] Graphite powder is immersed in a solution of sulfuric acid, nitric acid, and potassium permanganate for between 1 to 24 hours at room temperature. The powder is dried and subjected to thermal shock treatment, e.g. a high temperature of 1,000° C. for 15-30 seconds under the flow of Ar gas. The thermal shock leads to the formation of exfoliated graphite worms, which are then subject to ultrasonication for 30 minutes. The ultrasonication causes mechanical shearing of the exfoliated graphite flakes into graphene containing two or more sheets or layers. Example 2 [0051] Natural graphite flake from Sigma Aldrich was immersed in a solution of sulfuric acid and hydrogen peroxide (v/v=20/1) solution at 90° C. in a water bath for 1 hour. The powder was dried and then subjected to a thermal shock at 1000° C. for 45 seconds to obtain exfoliated graphite worms. The exfoliated graphite was then dispersed in n-methylpyrrolidone (NMP) under ultrasonication for 1 hour to form graphene. Example 3 [0052] The same process is followed as in Example 1, except the thermal shock treatment was done under the flow of ammonia gas to prepare N-doped graphene. Example 4 [0053] Si-graphene nanocomposite material was prepared by following the same process as in Example 1 to prepare graphene, or as in Example 3 to prepare N-doped graphene. Silicon is then deposited on doped or un-doped graphene and between the sheets or layers of graphene by chemical vapor deposition (CVD) process. The chamber is first purged with flowing Ar for 30 minutes and then heated to 550° C. Silane gas (SiH 4 ) is added to a CVD reactor containing the doped or un-doped graphene and the silane gas is allowed to infuse the graphene for about 60 minutes. The heating decomposes the silane gas into silicon particles and hydrogen gas. Upon cooling, a layered nanocomposite material with graphene and silicon is formed. Scanning electron microscope (SEM) and transmission electron microscope (TEM) images confirmed that some of the silicon particles are intercalated within the layers of the graphene. Example 5 [0054] A nanocomposite material was prepared by following same the process as Example 1 to prepare graphene, or Example 3 to prepare N-doped graphene. The doped or un-doped graphene is placed in a fluidized CVD reactor and pre-heated to 850° C. Liquid trichlorosilane (TCS) is injected into the low-temperature zone (100° C.) of a CVD reactor and vaporized. The TCS vapors are then carried downstream to the high temperature zone by hydrogen to the graphene where the TCS subsequently decomposes on and between the sheets or layers of the graphene. The nanocomposite material contains Si nanoparticles distributed within and on the graphene. Example 6 [0055] An electrode was made by casting slurry of 70 wt % of un-doped Si-graphene, 20 wt % acetylene black, and 10 wt % polyimide, dispersed in N-Methyl-2-pyrrolidone (NMP), on a copper foil, and drying completely in a vacuum oven at 75° C. overnight. The material was then subjected to a high temperature treatment at about 400° C. for 1 hour under flowing N 2 gas. Example 7 [0056] Testing of the electrodes. 2032-type coin cells were prepared with a Li foil as a negative electrode, a 25 μm Microporous Trilayer Membrane (Celgard 2325) as separator, the above doped and un-doped electrodes as the positive electrode and sufficient amount of electrolyte. The electrolyte was 10 wt % of fluoroethylene carbonate (FEC) dissolved in a 3:7 by weight mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) containing 1.2M LiPF 6 . [0057] The electrochemical performance of doped and un-doped Si-Graphene composite materials were tested using computerized battery test systems manufactured by Maccor, Inc. The cell was run between 0.02 V to 1.2 V with a constant current of 100 mA/g for the first two cycles and followed by 400 mA/g load. [0058] FIG. 2 shows the cycle performance and efficiency of Si-Graphene (undoped) composite materials. The reversible capacity of these Si-Graphene composites materials is 1173 mAh/g after 80 cycles at C/3 rate, with only 4.25% reversible capacity loss. The results demonstrate that Si-Graphene composite materials exhibit over three times the reversible capacity of graphite materials (less than 372 mAh/g). [0059] FIG. 3 shows the cycle performance of Si-Graphene composite materials (undoped) as compared to a bulk Si electrode. The reversible capacity of these Si-Graphene composites materials is 1173 mAh/g after 80 cycles at C/3 rate, with only 4.25% reversible capacity loss. The Si-Graphene nanocomposite has significantly improved reversible capacity as compared to Si. Thus, the nanocomposites exhibit a significant increase in specific capacity together with significant improvements in long term stability when used as an anode material. The results demonstrate that Si-Graphene composite materials exhibit high reversible capacity of 1173 mAh/g, which is over three times the reversible capacity of graphite materials (less than 372 mAh/g). Example 8 [0060] Composite Si-Graphene material prepared using Example 4 or 5 was heated to 950° C. under the presence of hydrogen gas for 120 minutes to prepare a reduced Si-Graphene nanocomposite material. Other reducing gases, in addition to, or instead of, hydrogen may be used. Example 9 [0061] The reduced Si-Graphene nanocomposite material prepared according to Example 8 is fashioned into electrode and placed in coin cell as described in Example 7. The electrochemical performance of the coin cell with the reduced Si-Graphene material is compared to the Si-Graphene coin cell prepared in Example 6 in FIG. 4A and 4B as the cells are subjected to the first charging cycle. The reduced Si-Graphene material (Si-G1-HTR-1st C) has a larger first cycle efficiency of 88.3% as compared to the efficiency of the Si-Graphene material (Si-G1-1st C), 77.6%. Sample in FIG. 4A has silicon loading of 27 wt %, while it is 35 wt % for FIG. 4B . The labels with the “C” are the charging cycles and the “D” labels for the discharging cycles. The HTR labels refer to the hydrogenated (i.e. reduced) samples. [0062] In FIG. 5 , the reversible capacity of the reduced Si-Graphene material was compared to the Si-Graphene material used in Example 6. The coin cells were tested at C/3 rate for 50 cycles. The reversible capacity of the reduced Si-Graphene is 876 mAh/g compared with 725 mAh/g for untreated Si-Graphene material, corresponding to an improvement of 20.8%. Furthermore, the reduced Si-graphene has higher stability than the un-reduced material. [0063] While certain embodiments have been illustrated and described, it should be understood that changes and modifications can be made therein in accordance with ordinary skill in the art without departing from the technology in its broader aspects as defined in the following claims. [0064] The embodiments, illustratively described herein may suitably be practiced in the absence of any element or elements, limitation or limitations, not specifically disclosed herein. Thus, for example, the terms “comprising,” “including,” “containing,” etc. shall be read expansively and without limitation. Additionally, the terms and expressions employed herein have been used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the claimed technology. Additionally, the phrase “consisting essentially of will be understood to include those elements specifically recited and those additional elements that do not materially affect the basic and novel characteristics of the claimed technology. The phrase “consisting of excludes any element not specified. [0065] The present disclosure is not to be limited in terms of the particular embodiments described in this application. Many modifications and variations can be made without departing from its spirit and scope, as will be apparent to those skilled in the art. Functionally equivalent methods and compositions within the scope of the disclosure, in addition to those enumerated herein, will be apparent to those skilled in the art from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled. It is to be understood that this disclosure is not limited to particular methods, reagents, compounds compositions or biological systems, which can of course vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. [0066] For the purposes of this disclosure and unless otherwise specified, “a” or “an” means “one or more”. [0067] In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group. [0068] As will be understood by one skilled in the art, for any and all purposes, particularly in terms of providing a written description, all ranges disclosed herein also encompass any and all possible subranges and combinations of subranges thereof. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein can be readily broken down into a lower third, middle third and upper third, etc. As will also be understood by one skilled in the art all language such as “up to,” “at least,” “greater than,” “less than,” and the like, include the number recited and refer to ranges which can be subsequently broken down into subranges as discussed above. Finally, as will be understood by one skilled in the art, a range includes each individual member. [0069] All publications, patent applications, issued patents, and other documents referred to in this specification are herein incorporated by reference as if each individual publication, patent application, issued patent, or other document was specifically and individually indicated to be incorporated by reference in its entirety. Definitions that are contained in text incorporated by reference are excluded to the extent that they contradict definitions in this disclosure. [0070] Other embodiments are set forth in the following claims.

A process for producing nanocomposite materials for use in batteries includes electroactive materials are incorporated within a nanosheet host material. The process may include treatment at high temperatures and doping to obtain desirable properties.

RELATED PATENTS AND APPLICATIONS U.S. Patent Documents [0001] [0000] 6,355,865 March 2002 Elmstrom 2003/0121075 June 2003 Barham, Warren S. 2003/0163852 August 2003 Barham, Robert; et al. 6,759,576 July 2004 Zhang, et al. 2006/0137044 June 2006 Lanini; Brenda; et al. OTHER REFERENCES [0000] American Diabetes Association website—accessed Mar. 17, 2008 Bassett, Mark J. (editor), 1986, Breeding Vegetable Crops, AVI Publishing Company, Inc. Central Intelligence Agency website—accessed Mar. 17, 2008 Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, HS1079, January 2007 Glich et al., (Eds), 1993, Methods in Plant Molecular Biology & Biotechnology, CRC Press Harvard School of Public Health website—accessed Mar. 17, 2008 Maynard, D. N. (editor), 2001, Watermelon Characteristics, Production and Marketing, ASHS Press National Agricultural Statistics Service of USDA—January 2006 Rhodes & Dane, 1999, Gene List for Watermelon, Cucurbit Genetics Cooperative Report 22:71-77 University of Sydney—Glycemic Index and GI database—accessed Mar. 17, 2008 Zhang, Xing-ping & Jiang, Yi, 1990, Edible Seed Watermelons ( Citrullus lanatus (Thunb. Matsum. Nakai) in Northwest China, Northwestern Agricultural University, China. FIELD OF THE INVENTION [0012] This invention is in the field of watermelon breeding, specifically relating to diploid watermelon plants producing fruit with reduced sugar content, and also serving the function of pollinating triploid watermelon plants for the commercial production of seedless watermelon fruit. BACKGROUND OF THE INVENTION [0013] Watermelon is an important horticultural crop with over 137,000 acres grown in the United States in 2005. The leading watermelon producing states are Florida, Georgia, Texas, and California with a combined total of 86,300 acres. (National Agricultural Statistics Service of USDA—January 2006) [0014] The popularity of seedless (triploid) watermelon has increased over the last decade. During peak watermelon production in the U.S. market in 2005 and 2006, seeded watermelons only comprised 22% of the market and averaged four to five cents less per pound (Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, HS1079, January 2007). [0015] Population of the United States is estimated at over 300 million as of July 2007 (Central Intelligence Agency website). [0016] Of the 20.8 million Americans with diabetes, 90 to 95 percent have type 2 diabetes. (American Diabetes Association website). This amounts to 7% of the total population of the United States. [0017] The glycemic index (GI) is a ranking of foods on a scale from 0 to 100 according to the extent to which they raise blood sugar levels after eating. Foods with a GI of 70 or above are considered high GI foods. Watermelon is rated at 72 which is considered a high GI. (University of Sydney Glycemic Index and GI database) [0018] Glycemic index in watermelon can be lowered by decreasing its sugar content. [0019] Lower GI foods have been shown to help control type 2 diabetes and improve weight loss. (Harvard School of Public Health—website) [0020] The goal of plant breeding is to combine in a single variety or hybrid various desirable traits. Desirable traits may include resistance to diseases and insects, tolerance to heat and drought, reducing the time to crop maturity, greater yield, and better agronomic quality. Other desired traits may include particular nutrient content, color, fruit shape, as well as taste characteristics. [0021] As with many different plants, watermelon contains a fruit part and a plant part. Each part contains different traits that are desired by consumers and/or growers, including such traits as flavor, texture, disease resistance, and appearance traits such as shape and color. Reduced sugar is a highly desirable trait for consumers with type 2 diabetes. The seedless trait in the watermelon fruit is also highly desired by consumers. Extended flowering in diploid watermelon plants is a trait sought after by growers of seedless watermelon. [0022] Seeded watermelon plants are diploid and can be self-pollinated either by bees or by hand. [0023] Seedless watermelon plants are triploid and must be pollinated by the pollen of diploid watermelon plants. The two primary methods currently in practice to pollinate seedless watermelon plants are; 1) planting traditional hybrid diploid varieties (e.g. Sangria produced by Syngenta, Inc.) in dedicated rows and harvesting and selling both the diploid fruit and the seedless fruit, or 2) inter planting between triploid watermelon plants within rows of triploid plants special pollenizer plants (e.g. SP-1 produced by Syngenta, Inc.), with plant characteristics especially favorable for pollination, which produce non-marketable fruit due their poor fruit quality, in particular a thin explosive rind making it difficult to harvest and transport the fruit. Due to the non-marketable fruit that these special pollenizer plants produce, they are generally referred to as “Non-Harvestable Pollenizers”. [0024] The present invention recognizes the need to provide consumers with type 2 diabetes a watermelon with reduced sugar and therefore with less total carbohydrates, and a lower glycemic index. The present invention also recognizes that a method of producing reduced sugar watermelons is needed that reduces the economic risk of producing this product which has a relatively limited market (less than 7% of the total market). BRIEF SUMMARY OF THE INVENTION [0025] The present invention uses a novel diploid watermelon to provide a product to the consumer segment, which includes those suffering from type 2 diabetes in an economical manner. According to the invention, there is provided a novel reduced sugar watermelon (hereinafter referred to as “dual purpose reduced sugar watermelon”) and a method for producing it in an economical manner by using it as a pollenizer for seedless watermelon production. In other words, it will be produced as a byproduct of seedless watermelon production. [0026] In addition to reduced sugar, the present invention includes a dual purpose reduced sugar watermelon with the following additional fruit traits enabling the successful production and marketing of this watermelon; 1) relatively firm flesh desired by consumers, 2) tough rind thereby reducing breakage of fruit during harvesting and transport, 3) rind color distinguishable from other watermelon fruit currently in the market in the United States, and 4) small fruit enabling consumers to purchase a “single portion”. The small fruit also helps to increase flowering, which contributes to the invention's second purpose as a pollenizer for seedless watermelon production. [0027] The present invention further includes a dual purpose reduced sugar watermelon comprising a plant with the following characteristics favorable for its second purpose as a pollenizer for seedless watermelon production; 1) extended flowering duration providing pollen to seedless watermelon plants over an extended time period, 2) thin leaves thereby shading seedless watermelon plants located in close proximity to a lesser degree, and 3) long thin sprawling vines providing pollen over a larger surface area. [0028] Also included in this present invention is a method of producing reduced sugar watermelons as a byproduct making the reduced sugar watermelon crop more economically feasible. This is accomplished by using the reduced sugar watermelon plant as a pollenizer for seedless watermelon production. The reduced sugar watermelon plants can be planted within seedless watermelon fields as a pollenizer in any of the currently practiced manners, and the fruit of the reduced sugar watermelon can be harvested and sold. [0029] The dual purpose reduced sugar watermelon of the invention is further enhanced by including resistance to various pests and herbicides via conventional plant breeding methods or genetic transformation. [0030] The dual purpose reduced sugar watermelon of the invention is further enhanced by various flesh colors including orange or yellow or white or red via conventional plant breeding methods or genetic transformation. DETAILED DESCRIPTION OF THE INVENTION [0031] Development of Dual Purpose Reduced Sugar Watermelon [0032] According to the present invention, a watermelon OW824 is selected having the characteristics of an extended flowering duration, small leaves with deep, non-overlapping leaf lobes, a long sprawling vine, firm flesh, tough rind, and low sugar content. In this example, the fruit of OW824 is relatively large, the rind and flesh are very firm, the seed size is very big, and the flesh is white. OW824 is a publicly available edible seed watermelon variety generally referred to as Xinjiang Edible Seed Watermelon. [0033] Also according to the invention, a watermelon Mickylee (PI 601307) is selected for its rind color which is distinguishable from other watermelon fruit on the market in the United States. In this example, Mickylee has a firm red flesh, light green rind, and weighs 4 to 5 Kg. Mickylee is publically available from the USDA—AMS National Genetic Resources Program. [0034] Also according to the invention, diploid inbred watermelon line GSX-26, a proprietary Gold Seed Co. breeding line is selected for its small size (average weight of 1.5 Kg.). In this example, GSX-26 has fruit with the following characteristics; jubilee type striped rind pattern, thin rind, sweet red flesh, oval shape with small seeds. The plant is of medium vigor, high fruit set, and with very early maturity. [0035] The first step was to cross Mickylee to GSX-26, and then hybrid progeny were crossed to OW824 to form a three way cross. [0036] This three way cross generated progeny having the characteristics of the dual purpose reduced sugar watermelon of the present invention as described in more detail below. [0037] The initial cross of Mickylee X GSX-26 was made during the spring of 2005 in Israel. This hybrid was further crossed with OW824 in Summer 2005 in Israel. The three-way cross produced was self-pollinated in spring 2006 in Israel. The F2 generation was grown in the summer of 2006. Individuals with the set of traits required for the dual purpose reduced sugar watermelon were successfully identified and self-pollinated in the F2 population. A total of 4 selections were made. The 4 F3 lines were grown in Israel in Spring 2007 for further selection and evaluation. 1 F3 line was identified to best meet our breeding goals and advanced to the F4 generation. This one line, Escort-4, called 121-14, is fixed for every trait concerned. Escort-4 contains the traits that are illustrative of the traits of the dual purpose reduced sugar watermelon of the invention. Other examples of dual purpose reduced sugar watermelon lines with similar characteristics were 121-5 with yellow/pink flesh, 121-7 with white flesh, and 121-11 with slightly larger fruits and a different rind color. [0038] Fruit: The fruit of the dual purpose reduced sugar watermelon, e.g. of Escort-4, has approximately ⅓ less sugar content compared to the most popular diploid varieties currently marketed. Fruit of Escort-4 and the most popular diploid variety currently on the market called Sangria (Syngenta, Inc.) were harvested at full maturity on May 7, 2008, and tested for Total Soluble Sugars (TSS) for comparison purposes as shown in Table 1 below. In this comparison, fruit of Escort-4 had an average TSS content of 32% less than Sangria. [0000] TABLE 1 Escort-4 % TSS Sangria % TSS Fruit #1 9.5 Fruit #1 12.8 Fruit #2 9.1 Fruit #2 13.4 Fruit #3 8.6 Fruit #3 12.7 Fruit #4 8.8 Fruit #4 13.6 Fruit #5 8.5 Fruit #5 12.6 Fruit #6 8.6 Fruit #6 13.7 Fruit #7 8.9 Fruit #7 13 Fruit #8 8.3 Fruit #8 12.7 Fruit #9 10.1 Fruit #9 12.5 Fruit #10 8.4 Fruit #10 14 Average 8.9 Average 13.1 [0039] The flesh of the dual purpose reduced sugar watermelon, e.g. of Escort-4, is relatively firm. The flesh pressure when measured by a penetrometer (Model No. FT011 of Wagner Instruments, Greenwich, Conn. 06836) is in the range of approximately 2 lbs./inch to approximately 4 lbs./inch. The average flesh pressure is approximately 3 lbs./inch. [0040] In addition, the fruit of the dual purpose reduced sugar watermelon, e.g. of Escort-4, compared to one of the more popular “non-harvestable” diploid pollenizers on the market called SP-1 (Syngenta, Inc.), has a much tougher rind, which resists breakage as opposed to the brittle fruit rind of SP-1 that splits easily and therefore can not be shipped easily if desired. Brittleness is conferred by a gene e (explosive rind, thin, and tender rind, bursting when cut (Rhodes & Dane, 1999, Gene List for Watermelon, Cucurbit Genetics Cooperative Report 22:71-77). The fruit of this invention does not contain this e gene and therefore has the ability to be harvested and transported long distances with minimal damage. For comparison purposes, fully mature fruit of Escort-4 and SP-1 were harvested on May 7, 2008 and measured for rind breakage pressure by a penetrometer (Model No. FT327 with a tip FT516— 5/16 diameter of Wagner Instruments, Greenwich, Conn. 06836). The Escort-4 fruit broke at 16-22 lbs./in., whereas fruit of SP-1 broke at 7-10 lbs./in. The rind of Escort-4 resists more than double the pressure as compared to SP-1. See TABLE 2 below. [0000] TABLE 2 Breakage Breakage Pressure Pressure Escort-4 (Lbs./Inch) SP-1 (Lbs./Inch) Fruit #1 22.5 Fruit #1 9.5 Fruit #2 16 Fruit #2 8.5 Fruit #3 17 Fruit #3 7.5 Fruit #4 21 Fruit #4 10 Fruit #5 19.5 Fruit #5 7 Fruit #6 21 Fruit #6 8 Fruit #7 18.5 Fruit #7 7.5 Fruit #8 17.5 Fruit #8 7.5 Fruit #9 18 Fruit #9 8.5 Fruit #10 17 Fruit #10 9.5 Average 18.8 Average 8.3 [0041] The fruit of the dual purpose reduced sugar watermelon of the invention, e.g. of Escort-4, can be distinguished from the fruit of all of the most popular commercially available seedless watermelon varieties marketed in the United States. The rind color of the dual purpose reduced sugar watermelon is preferably light green with slightly noticeable very thin medium green lines. [0042] Preferably, the fruit size of the dual purpose reduced sugar watermelon, e.g. of Escort-4, is small being approximately in the range of about 5 to about 7 inches long, and in the range of about 4 to about 5 inches wide. Small fruit size was selected to decrease the load on the plant, thereby extending the duration of plant growth and flower production. Another advantage of the small fruit size is that it can be marketed as a single serving fruit providing an option for individuals wanting to enjoy watermelon without having the excess from a typically large fruit. The fruit of the dual purpose reduced sugar watermelon weighs approximately in the range of about 2 to about 7 lbs, preferably about 2 to about 6 lbs. The average weight for the fruits of the dual purpose reduced sugar watermelon is preferably about 4.0 lbs. [0043] Flowering: The plants of the dual purpose reduced sugar watermelon, e.g. of Escort-4, are very vigorous and continue flowering over a relatively long period. The plant of this invention begins flowering approximately 7 days earlier than diploid reference variety Sangria. It continues to flower for approximately 7 weeks, which is when the most common seedless watermelon varieties finish harvesting. It therefore flowers during the entire flowering period of seedless watermelons currently in the market, thereby providing a continuous supply of diploid watermelon pollen to seedless watermelon plants during the critical time period. [0044] Leaf: The leaves of the dual purpose reduced sugar watermelon, e.g. of Escort-4, are similar to the Xinjiang Edible Seed Watermelon. The leaves of the dual purpose reduced sugar watermelon preferably have a surface area approximately in the range of about 20 to about 70 cm 2 , preferably about 22.5 to about 50 cm 2 . The leaves of the dual purpose reduced sugar watermelon preferably have deep, non-overlapping leaf lobes. These thin leaves shade seedless watermelon plants located in close proximity to a lesser degree than diploid watermelon Sangria, which is a variety favored by many growers. [0045] Vine: The vines of the dual purpose reduced sugar watermelon, e.g. of Escort-4, are long, thin, and sprawling similar to the Xinjiang Edible Seed Watermelon. Length of vine at first harvest is approximately 1.7 to 2.3 meters. Diameter of the vine is approximately 4 to 6 mm at the second node. The long sprawling vine provides pollen to seedless watermelon plants over an extended surface area. [0046] Other Traits: The dual purpose reduced sugar watermelon, e.g. Escort-4, can be used either as donor of the set of traits disclosed above, or as the recurrent parent to develop additional dual purpose reduced sugar watermelon lines. In accordance with the invention, the dual purpose reduced sugar watermelon contains traits of disease resistance (e.g. Fusarium wilt, Anthracnose, Gummy Stem Blight, Powdery Mildew, and Bacterial Fruit Blotch), insect resistance (e.g. cucumber beetle, aphids, white flies and mites), salt tolerance, cold tolerance, and/or herbicide resistance added. In addition, the dual purpose reduced sugar watermelon contains various flesh colors (e.g. orange or white or yellow or red). These traits can be added to existing lines by using either the conventional backcrossing method, pedigree breeding method or genetic transformation. The methods of conventional watermelon breeding are taught in several reference books, e.g. Maynard, D. N. (editor), 2001, Watermelon Characteristics, Production and Marketing, ASHS Press; and Bassett, Mark J. (editor), 1986, Breeding Vegetable Crops, AVI Publishing Company, Inc. General methods of genetic transformation can be learned from published references, e.g. Glich et al., (Eds.), 1993, Methods in Plant Molecular Biology & Biotechnology, CRC Press. [0047] Forms of the Dual Purpose Reduced Sugar Watermelon: Once the dual purpose reduced sugar watermelon lines are developed, several forms of dual purpose reduced sugar watermelon varieties can be used in commercial watermelon production. Specifically, these forms of dual purpose reduced sugar watermelon varieties include: (1) Open Pollinated Variety: The stable lines of the dual purpose reduced sugar watermelon are grown in isolated fields, at least 2,000 meters from other watermelon varieties. Pollination is conducted in the open fields by bees. Seeds are harvested from the seed production field when the fruit and seeds are fully developed. The seeds are dried and processed according to standard watermelon seed handling procedures. (2) Hybrid Variety: Two dual purpose reduced sugar watermelon lines, the male and female parents, are planted in the same field. Hand pollination is conducted. Only the seed from the female parent line is harvested and sold to the commercial grower for use. [0048] Method of producing reduced sugar watermelons as a byproduct: In order to produce the reduced sugar watermelons in an economical manner the dual purpose reduced sugar watermelon can be used as a pollenizer for seedless watermelon production. It can be planted as a pollenizer in both of the most common currently practiced methods, which are; 1) planting the dual purpose reduced sugar watermelon in separate dedicated rows before and after every 2nd row of seedless watermelon plants, and the seedless watermelon fruit and the reduced sugar watermelon fruit would then be harvested and sold, or 2) inter planting between triploid watermelon plants with no dedicated space for the dual purpose reduced sugar watermelon plants within the same rows as the seedless watermelon plants between every 2nd or 3rd or 4th or 5th plant. Both the seedless watermelon fruit and the reduced sugar watermelon fruit would then be harvested and sold. Therefore, a dedicated field for production of reduced sugar watermelons is not necessary. Deposit [0049] Applicant has made a deposit of at least 2500 seeds of the Dual Purpose Reduced Sugar Watermelon line Escort-4 at The National Collections of Industrial and Marine Bacteria Limited (NCIMB), Ferguson Building, Craibstone Estate, Bucksburn, Aberdeen AB21 9YA, Scotland, UK under number NCIMB 41542 in order to illustrate the invention. This deposit of the Dual Purpose Reduced Sugar Watermelon line Escort-4 will be maintained in the NCIMB depository, which is a public depository, for a period of 30 years, or 5 years after the most recent request, or for the effective life of the patent, whichever is longer, and will be replaced if it becomes nonviable during that period. Additionally, applicant has satisfied all the requirements of 37 C.F.R. sections 1.801-1.809, including providing an indication of the viability of the sample. Applicant imposes no restrictions on the availability of the deposited material from the NCIMB; however, applicant has no authority to waive any restrictions imposed by law on the transfer of biological material or its transportation in commerce. Applicant does not waive any infringement of its rights granted under this patent. [0050] The foregoing invention has been described in detail for purposes of clarity and understanding. However, it will be obvious that certain changes and modifications such as single gene modifications and mutations, somaclonal variants, variant individuals selected from large populations of the plants of the instant inbred and the like may be practiced within the scope of the invention, as limited only by the scope of the appended claims. Thus, although the foregoing invention has been described in some detail in this document, it will be obvious that changes and modifications may be practiced within the scope of the invention, as limited only by the scope of the appended claims.

The invention relates to a diploid watermelon having fruit with approximately ⅓ lower sugar content than common watermelons found in the market place, and plant characteristics favorable for use as a pollenizer for commercial production of seedless watermelons. In addition to reduced sugar, fruit characteristics of the invention include a tough rind, firm flesh, distinct rind color, and small fruit. The watermelon plant of the invention has the characteristics of extended flowering duration, thin leaves, and long sprawling vines. The invention combining the above mentioned fruit and plant characteristics can serve the dual purpose of producing reduced sugar watermelon fruit, and pollinating seedless watermelons. This will in effect produce reduced sugar watermelons which are beneficial for consumers with type 2 diabetes as a byproduct of commercial seedless watermelon production making the product more economically feasible.

TECHNICAL FIELD [0001] The present invention relates to a locking device and an overriding drive for an overriding steering system, wherein a steering angle inputted by the driver can be overridden by another angle by means of a control according to correcting variables. BACKGROUND OF THE INVENTION [0002] Up-to-date motor vehicles, in particular passenger vehicles, are generally equipped with hydraulic or electrohydraulic servo steering systems, wherein a steering wheel is forcibly coupled mechanically to the steerable vehicle wheels. The power assistance is so configured that actuators, e.g. hydraulic cylinders, are arranged in the mid-area of the steering mechanism. A force generated by means of the actuators assists the actuation of the steering mechanism in response to the rotation of the steering wheel. This arrangement reduces the force the driver has to exert during the steering maneuver. [0003] Overriding steering systems are disclosed in DE 101 59 800 A1 and DE 101 59 700 A1, the contents of which are part of the application and on which the application is based. Said overriding steering systems are characterized in that it is possible for an actuator to superimpose another angle, if required, on the steering angle inputted by the driver. The additional angle is defined by a controller and used to enhance the stability and agility of the vehicle. It is also feasible to compensate disturbances and to realize the gradient wheel steering angle by way of the steering wheel angle as a function of the driving speed of the vehicle. Hydraulic or electric actuators are used. BRIEF SUMMARY OF THE INVENTION [0004] An object of the invention is to provide an overriding drive or a locking device, wherein the driver can apply a steering angle to the wheels of the vehicle when the electronics or the energy supply fails. [0005] According to the invention, this object is achieved in that the overriding drive is locked electromechanically in dependence on further correcting variables representative of an operating state of the vehicle. In the overriding drive, a superposition with another angle allows additionally or simultaneously changing the transmission ratio in a favorable way. The overriding drive of the overriding steering system according to the invention in particular enables a safe and comfortable operation. [0006] It is advantageous that quantities such as ignition on/off, engine rotational speed and like factors are monitored to detect the operating state, and that the quantities are analyzed for detecting whether the engine is or is not switched off or an energy supply is or is not safeguarded, respectively. The plausibility of the motor's position and of the sensor signals is monitored to enhance the reliability in operation. [0007] In a favorable embodiment, the overriding drive includes a freewheeling mechanism, which is lockable in operative and/or positive engagement. [0008] The activation of the locking is preferably switchable and, in an especially preferred fashion, it takes place simultaneously for the operative and positive locking. [0009] In another favorable design, the operative locking is provided by at least one first clamping member, preferably by three to nine clamping members, being brought into frictional contact with an inner ring of the freewheeling mechanism by way of a radial actuation, while the positive locking is provided by at least one second clamping member, preferably by three to nine clamping members, being brought into a form-fit contact with the inner ring of the freewheeling mechanism by way of a radial actuation. [0010] In addition, it is favorable that a first actuating ring is associated with the freewheeling mechanism for the positive connection and a second actuating ring is associated therewith for the frictional connection, said rings being entrained with the clamping members upon radial actuation thereof so that rotation of the inner ring is prevented by means of a clamping contour at an outer ring of the freewheeling mechanism. Favorably, a defined angle, i.e. twisting angle, is allowed due to the frictional connection before a positive connection develops. [0011] The object of the invention is also achieved by way of a locking device that is preferably provided for an overriding drive of the type described hereinabove and characterized by the provision of a freewheeling mechanism, which is operatively and/or positively lockable. [0012] The activation of the locking is preferably switchable and, in an especially preferred fashion, it takes place simultaneously for the operative and positive locking. [0013] In a favorable design, the operative locking is provided by at least one first clamping member, preferably by three to nine clamping members, being brought into frictional contact with an inner ring of the freewheeling mechanism by way of a radial actuation, while the positive locking is provided by at least one second clamping member, preferably by three to nine clamping members, being brought into a form-fit contact with the inner ring of the freewheeling mechanism by way of a radial actuation. [0014] Preferably, the first clamping member is elastically arranged and permits a defined angle, i.e. twisting angle. [0015] It is arranged for by the invention that a first actuating ring is associated with the freewheeling mechanism for the operative or frictional connection and a second actuating ring is associated therewith for the positive connection, said rings being entrained with the clamping members upon radial actuation thereof so that rotation of the inner ring is prevented by means of a clamping contour at an outer ring of the freewheeling mechanism. [0016] Advantageously, it is provided that locking is effected by an electromechanical transducer that includes a first actuating element for the operative or frictional connection and a second actuating element for the positive connection, said actuating elements acting on the clamping members and being moved by an electromagnetically operable armature in opposition to a spring force for the purpose of locking or unlocking the freewheeling mechanism. This design according to the invention renders it possible to safely fix or lock an element that shall be locked by using very low adjusting and retaining forces and, thus, only low (electrical) energy. The result is that only a small mounting space is required. [0017] According to the invention, the freewheeling mechanism has a stepped contour so that the inner ring is initially retained by means of a frictional connection. BRIEF DESCRIPTION OF THE DRAWINGS [0018] In the drawings, [0019] FIG. 1 is a schematic general overview of the overriding steering system of the invention. [0020] FIG. 2 is a schematic view of a planetary gear with a freewheeling mechanism and a locking device according to the invention. [0021] FIG. 3 is a view of the freewheeling mechanism with locking device. [0022] FIG. 4 is a perspective view of the freewheeling mechanism. [0023] FIG. 5 is a top view of a section of the freewheeling mechanism with locking device. [0024] FIG. 6 is a first section of the freewheeling mechanism with locking device. [0025] FIG. 7 is a second section of the freewheeling mechanism with locking device. [0026] FIG. 8 is a side view of a section of the freewheeling mechanism. [0027] FIG. 9 is a section of the freewheeling mechanism with locking device in the de-energized condition. [0028] FIG. 10 is a section of the freewheeling mechanism with locking device in the energized condition. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0029] The overriding steering system shown in FIG. 1 includes a hand steering wheel 50 that is connected to a steering rod 53 by way of a steering column 51 , into which an overriding drive 6 is inserted, and by way of a steering gear 52 . Displacement of the steering rod 53 permits turning of the wheels 54 , 55 . Turning of the wheels 54 , 55 is assisted by means of a hydraulic unit 56 and by a corresponding control of the hydraulic pressure by means of a valve unit 57 . A pump 58 generates the pressure. [0030] The function of an overriding drive 6 in the overriding steering system shown in FIG. 1 involves adjusting an overriding angle 12 irrespective of the driver through a control by means of correcting variables which can be produced e.g. by a driving dynamics system (ESP controller). To this end, a planetary gearing with two sun wheels and three step planet pinions as described in DE 101 59 8000 A1 or DE 101 59 700 A1 is used. The step planet pinions are mounted in a satellite carrier (cage) . However, the invention is expressly not limited to a planetary gearing as overriding drive 6 . Thus, all other pick-off gears known in the art may be used as well. [0031] The transmission ratio of the vehicle steering system is composed of the transmission ratio of the steering gear and the overriding drive. Where the objective is to modify the transmission ratio to a defined transmission ratio, it is necessary to additionally drive a component of the overriding drive. Said driving is carried out by way of an electric motor (E-Motor) 8 , whereby the variation of the transmission ratio is possible in a wide range. [0032] The motor 8 can be coupled to the gear 6 , thus, to the planet cage in the case of a planetary gearing, by means of a self-locking gear (worm gear or helical gear) or a non self-locking gear (drawing means gearing or toothed gearing) Preferably, however, a drawing means gearing, in particular a belt drive, is used. [0033] To realize a fixed transmission ratio in operating states when the motor 8 is switched off, it is absolutely necessary to fix the overriding drive 6 . To this end, the cage is prevented from turning in a planetary gearing. This is possible by means of locking of the gear components to be locked, meaning the cage in a planetary gearing, e.g. in relation to a stationary housing, while a first gear shaft (gear input shaft) 7 is directly connected to a second gear shaft (gear output shaft) 9 by transmission means, especially through the planets of the gear. It is provided in the invention that the cage of the planetary gearing is positively and operatively lockable in dependence on the operating states. [0034] FIG. 2 schematically shows the locking device with a freewheeling mechanism and a planetary gearing as an overriding drive in more detail. [0035] The locking device 1 includes an electromechanical actuating unit 3 and a positive and operative freewheeling mechanism 2 . The locking device 1 is coupled positively to the gear housing 5 by way of a clutch 13 . Preferably, the locking device 1 is herein used in an electromechanical overriding steering system (ESAS) ( 4 ) for motor vehicles. Other ranges of application with similar safety-relevant requirements are also feasible for the locking device 1 . [0036] In the above-mentioned application, the gear housing 5 of the overriding drive 6 is locked by way of the locking device 1 in the non-activated condition or in the case of a fault. Thus, a throughgrip of the two gear shafts 7 , 9 is effected by way of the planetary gearing 10 with a transmission ratio iG 11 in a range of roughly 1:1.0 to roughly 1:1.2, preferably 1:1.1 or 1:1.2. The overriding steering angle 12 is locked then. [0037] The freewheeling mechanism 2 and the adjacent components of the locking device 1 are illustrated in FIGS. 3 to 8 in more detail. The locking device 1 of the invention is a functionally relevant component. In the de-energized condition of the electromechanical actuating unit 3 , the freewheeling mechanism 2 is locked by way of the one operatively connected freewheeling mechanism 14 and a positively connected freewheeling mechanism 15 . [0038] Said freewheeling mechanism 2 generally includes an outer ring 16 , an actuation throughgrip 17 , an immovable bearing 18 , a movable bearing 19 , a clamping member 20 for a frictional connection, a clamping member 21 for a positive connection, an actuating ring 22 for the frictional connection, an actuating ring 23 for the positive connection, a spring element 24 , and an inner ring 25 . [0039] When the clamping members 20 , 21 are actuated radially by means of an actuating force 26 in opposition to the spring force 27 induced by the spring elements 24 , the clamping members 20 , 21 will get into contact with the rotating or immovable inner ring 25 in frictional and positive connection (see FIGS. 6 and 7 ). The frictional and positive connection causes entrainment of the two actuating rings 22 , 23 by way of the spring force 27 and the positive connection 28 and operative connection with the clamping members 20 , 21 . The result is that the clamping members 20 , 21 are clamped between the outer ring 16 and the inner ring 25 by means of the clamping contour 29 provided in the outer ring 16 , and block further rotation 30 of the inner ring 25 on both sides. [0040] When the actuating force 26 is released again, the acting spring force 27 will produce a restoring torque 31 at the actuating rings 21 , 22 , and the clamping members 20 , 21 are reset to their zero position 32 when the rotation 30 is reversed. The resetting torque of the actuating rings 22 , 23 produced by the spring elements 24 is increased in the zero position 32 due to a special contour 33 of the clamping contour 29 . The embodiment illustrated in FIGS. 2 to 8 provides a high degree of functionality of the freewheeling mechanism 2 and ensures safe unlocking in the non-actuated condition. The actuating unit 3 of the locking device 1 is shown in detail in FIGS. 9 and 10 . The purpose of said unit is to ensure safe locking of the freewheeling mechanism 2 by means of a positive and frictional connection. The actuating unit 3 is substantially composed of an electromechanical transducer 34 , an armature 35 , an actuating element 36 for a frictional connection, an actuating element 37 for a positive connection, a compression spring 38 , and an armature spring 39 . [0041] In the energized condition (see FIG. 10 ), the armature 35 is attracted by means of the electromechanical transducer 34 in opposition to an integrated spring element 39 and maintains the two actuating elements 36 , 37 in their unlocking position 41 by means of an integrated stop 40 . Both freewheeling mechanisms 14 , 15 adopt their unlocked position. This allows free rotation of the inner ring 25 . The armature 35 is not positively connected to the electromechanical transducer 34 and is attracted and retained alone by way of electromagnetic air slot forces 42 . When the electromechanical transducer is separated from the housing 43 for mechanical reasons, the non-mechanical coupling to the armature 35 will cause the armature to instantaneously lock the freewheeling mechanism 2 by means of the armature spring 39 . [0042] When the current at the electromechanical transducer 34 drops, the armature spring 39 integrated at the armature 35 will urge the armature 35 downwards into the locking position 44 (see FIG. 9 ). The actuating forces 26 acting will activate both freewheeling mechanisms 14 , 15 to lock the inner ring 25 of the freewheeling mechanism 2 . Due to a stepped diameter 45 of the positive and frictional connection 14 , 15 , the freewheeling mechanism 2 is so configured that the frictional connection 14 will initially lock the inner ring 25 . When the frictional connection is creeping, the actuating element of the positive connection 37 loaded by the compression spring 38 will push the clamping member 21 and safely lock the positively connected freewheeling mechanism 15 . Safety is optimized in that there is no mechanical coupling between the electromechanical transducer 34 and the armature 35 . [0043] Thus, safe locking is ensured in every situation by means of the integration of a positively and operatively connected freewheeling mechanism 14 , 15 of the invention, effecting a high degree of operational safety of the electromechanical actuating unit 3 , while the positive connection is favorably used to ‘slow down’ the planet cage.

The present invention relates to an overriding drive for an overriding steering system, wherein a steering angle inputted by the driver can be overridden by another angle by means of a control according to correcting variables and the transmission ratio can be modified, and which is characterized in that the overriding drive is locked electromechanically in dependence on further correcting variables representative of an operating state of the vehicle.

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to PCT Application No. PCT/EP2015/053201, having a filing date of Feb. 16, 2015, based off of DE Application No. 10 2014 206 412.0 having a filing date of Apr. 3, 2014, the entire contents of which are hereby incorporated by reference. FIELD OF TECHNOLOGY The following point machines serve for switching the travel path of a rail vehicle on the rails. Said point machine is typically composed of an electric motor, the rotary motion of which is converted by way of a spindle rod or a gear rod to a linear motion. In most instances, a coupling which prevents excessive force being introduced to the rails is also part of the mechanical system. BACKGROUND In the course of the production or refurbishment of point machines the forces which are produced by the point machine finally have to be adjusted and tested. It is, inter alia, an objective that the forces which are generated by the point machine do not exceed or undershoot specific upper and lower limits, respectively. For this purpose, counterforces which correspond to the forces of the switch blade during later operation are applied to the point machine as a specimen while said point machine performs actuation procedures on the test bed. Furthermore, the test bed may also actively apply tensile forces to the specimen while the latter does not perform any actuation procedures. To this end, the point machine is placed on the test bed, is fastened thereto, connected to the testing system, tested, dismounted, and finally removed again. The mechanical dimensions of the point machines vary very much, depending on the field of application, the manufacturer, and the development history. In external terms, the common feature of all point machines is the so-called throw bar, which transmits the linear motion and force of the drive to the switch blade, and (optionally) the so-called check bars, which likewise are connected to the switch blade and enable mechanical feedback of the blade position to the drive. For testing, the point machine is ideally fastened in the same manner as the former is later fastened to the tracks (in most instances by way of a plurality of screw connections). By virtue of the dissimilar external dimensions of the drives, the two movable components in relation to the fastening points of the point machine are located at dissimilar positions. A variable test bench for point machines, which is composed of a basic module and replaceable testing modules, is known from the document “PT 10K Multi: variable test bench for point machines”, obtainable on the internet on Mar. 31, 2014 at http://www.probitron.de/fileadmin/pdf/datenblatt_multi.pdf. The basic module disposes of a hydraulic plant as a force generator, a controller, and measuring and safety technology. Individual testing modules which as per the depiction are each composed of one bench with rollers, and of position holders which are individually tailored to the point machine are available for various models of point machines. Adapting the coupling point between the specimen and the test-bed force generator is thus performed by mounting the specimen on a testing module which is individually tailored to the specimen. SUMMARY An aspect relates to an assembly and a method which provide an alternative to the state of the art for testing point machines. According to the following, this aspect is achieved by an assembly having at least one receptacle device. The receptacle device comprises at least two supports which are adapted for receiving a point machine as a specimen, or for receiving a mounting truck on which a point machine is mounted as a specimen, and a mechanism which is adapted for displacing the supports both in the horizontal direction and in the vertical direction. The assembly furthermore includes a test bed which disposes of a force generator which is adapted for applying counterforces to the specimen while the specimen on the test bed performs actuation procedures, on account of which the test bed is adapted for adjusting and/or testing forces which are generated by the specimen. The force generator and the mechanism in mechanical and electrical terms are mutually independent such that the supports are displaceable without being influenced by the test bed or by the force generator, on account of which a predefined coupled position between the specimen and the force generator is adjustable. In the case of the method for testing a point machine, at least two supports are displaced in both the horizontal direction and in the vertical direction by one mechanism. A point machine as a specimen is mounted on the supports. Alternatively, a mounting truck ( 20 ), to which a point machine as a specimen is fastened, is gripped and/or lifted by the mechanism by way of the supports. A test bed, by way of a force generator, applies counterforces to the specimen while the specimen on the test bed performs actuation procedures, wherein forces which are generated by the specimen are adjusted and/or tested. The supports prior to mounting of the specimen are displaced without being influenced by the test bed or by the force generator, on account of which a predefined coupled position between the specimen and the force generator is adjusted. The advantages which are mentioned hereunder need not necessarily be achieved by the disclosed subject matter. Rather, this herein may also be advantages which are achieved merely by individual embodiments, variants, or refinements. The receptacle device enables a multiplicity of specimens to be received, independently of the geometric dimensions of said specimens. To this end, said receptacle device provides a flexible adapter mechanism which, optionally in an automated manner, can be moved to required positions. A highly flexible solution is thus achieved. The assembly and the method enable an automated solution to fixing and coupling of the force transmission for the point machine. An advantageous effect is that the position of the force generator and of the sensitive measuring sensor assembly does not have to be moved in order for the applied forces to be fed back. Furthermore, it is guaranteed at all times that the introduction of force during measurement is performed in the motion direction. According to one embodiment, the mechanism is adapted for adjusting a horizontal spacing between the supports. This has the advantage that specimens having dissimilar widths may also be received and positioned with a good fit. In one refinement, the mechanism is adapted for displacing the supports in a mutually independent manner, both in the horizontal direction and in the vertical direction. This has the advantage that specimens having asymmetric dimensions may also be received and positioned with a good fit. According to one embodiment, the mechanism for displacing the supports in the horizontal direction and in the vertical direction has horizontal and vertical linear guides, in particular linear friction bearings, dovetail guides, profiled rail guides, or caged rail guides. Displacing of the supports herein, in particular in the horizontal direction, may be performed by manual displacement. The support in the target position is subsequently fixed by clamping. Alternatively or additionally, linear drives may be employed. In one refinement, the mechanism for each of the supports is specified with one dedicated horizontal linear drive and with one dedicated vertical linear drive, said linear drives both being adapted for automated displacement of the respective support to a required position. The linear drives enable highly accurate positioning of the supports in particular even when the latter have a high dead weight or are already loaded with the specimen. Furthermore, positioning of the supports may be automated by means of the linear drives. According to one embodiment, the mechanism is configured from at least two vertically mounted cross tables and/or vertically mounted X-Y linear drives, one of the supports being mounted on each thereof. Alternatively, both supports may be mounted on a single vertically mounted cross table or X-Y linear drive, on account of which the adjustment possibilities are limited, however. In one refinement, each support is mounted on a support slide which is displaceable by the respective linear drive. Each vertical linear drive is mounted on a transverse slide which is displaceable by the respective horizontal linear drive. According to one embodiment, the linear drives interact with in each case parallel guides which are constructed for guiding the respective slides. The linear drives each include one hydraulic or electric linear motor or linear actuator. In one refinement, the assembly includes a controller in which support positions depending on types of specimens are programmed, whereby the controller is adapted for actuating the linear drives and for automated displacing of the supports to the support positions. According to one embodiment, the mechanism by way of the supports is conceived for gripping and/or lifting a mounting truck, the specimen being fastenable thereto by a screw connection. To this end, the supports have fastening elements, in particular bolts, pins, gripping arms, depressions, or horizontal bores, which are disposed inboard and which permit the mounting truck to be gripped in particular by clamping the mounting truck between the supports. This offers the advantage that the specimen may be tested when mounted directly on the mounting truck, without separate repositioning and screwing down of the specimen being required. In one refinement, the supports have vertical threaded bores which permit fastening of the specimen by a screw connection. This offers the advantage that the specimen may be fastened in a like manner to being fastened to the rails. According to one embodiment, the supports have outboard fastening means, in particular dovetail profiles, which are screwed into horizontal threaded bores and which are adapted for fastening additional fastening elements, in particular clamps, for the specimen. This offers the advantage that specimens having previously unknown or unfavorable dimensions may also be securely fixed to the supports. In one refinement, the receptacle device is mounted on the test bed per se, or on the floor beside the test bed. According to one embodiment, the test bed has a test-bed interface which has at least one horizontal guide. The assembly furthermore has a slide which is displaceable along the horizontal guide. Furthermore, the assembly comprises at least two of the receptacle devices which are mounted beside one another on the slide. This embodiment offers the advantage that with the aid of the slide a second receptacle device and thus a second mounting position are provided. This means that during the testing procedure of a first point machine which is mounted in a testing position on the slide, a further point machine may already be mounted in a laterally offset manner on the other receptacle device, said further point machine being later moved to the testing position by lateral displacement of the horizontal slide. In one refinement, the assembly includes a running gear, in particular composed of rollers, wheels, or a guide, which supports the slide on a ground. According to one embodiment, the assembly includes at least one protective wall which is mounted between the receptacle devices on the slide. Alternatively, the assembly includes a protective hood which is mounted on the test bed. In one refinement, the assembly includes an adapter truck which has a frame on which the receptacle device is mounted. The frame has a truck interface by way of which the adapter truck is capable of being mechanically coupled to a test-bed interface of the test bed. The adapter truck may be connected to the test bed in a rapid and uncomplicated manner. In this way, it is also possible for adapting and testing to be completely separated from one another in spatial terms. A point machine which has once been adapted to the adapter truck may pass through various further testing installations (for example, electrical tests or running-in drives), without manual adapting having to be re-performed. Flexible adapting by means of the movable adapter truck enables the specimen to be loaded outside the test bed. This is advantageous, for example, if and when the test bed is not located in a region which is serviced by a crane. The adapter truck may be optionally docked beside a plurality of adapter stations and also to other testing stations such as for electrical tests or running-in procedures for the point-machine coupling. The adapter truck thus permits point machines to be dispatched by way of one or a plurality of test beds in a more rapid and, above all, an arbitrary sequence, without there being any additional tooling effort. The simple switching of stations has the additional advantage that the entire test procedure may be broken down such that expensive equipment is only required for individual test stations which are utilized in an optimal manner, and does not remain unutilized during other tests. Testing tasks which are simple yet time intensive may be outsourced to separate and simple test stations. According to one embodiment, the assembly includes an adapter station which is adapted for mechanically coupling the truck interface of the adapter truck to the adapter station, and by means of the mechanism for displacing the supports both in the horizontal direction and in the vertical direction. In one refinement, the mechanism for each of the supports has a drive shaft for a self-locking actuator gear for displacing the respective support in a direction X. Furthermore, the mechanism for each of the supports has a drive shaft for a self-locking actuator gear for displacing the respective support in a direction Y which is orthogonal to the direction X. According to one embodiment, the drive shafts each have a mechanical connector for transmitting torque, by way of which the drive shafts, when mechanically coupling the adapter truck to an adapter station, are capable of being automatically docked to actuators in the adapter station. In one refinement, the truck interface includes an electric plug connector which when mechanically coupling the adapter truck to the test bed or to the adapter station is automatically plugged into an electrical plug connector of the test-bed interface or of the adapter station. According to one embodiment, the adapter truck includes an actuator for each of the drive shafts. The adapter station by way of the electrical plug connectors provides electric power and control signals to the actuators, in order for the supports to be displaced. In one refinement, the assembly additionally comprises a mounting truck which is adapted for receiving the point machine and which is capable of being fixed by a form-fit between the supports. This refinement permits simple standard mounting trucks to be received directly between the supports for testing. To this end, the point machine is first mounted on the standard mounting truck. For subsequent testing, the mounting truck is tension-fitted to the adapter truck which may automatically dock to the various test stations and is capable of absorbing the testing forces. In the case of there being assembly lines which operate without mounting trucks, the specimen may also be screwed directly to the arms of the adapter truck. In one refinement of the method, the supports in a mutually independent manner are displaced both in the horizontal direction and in the vertical direction. According to one embodiment of the method, a controller, in which support positions depending on types of specimens are programmed actuates linear drives, and in an automated manner displaces the supports to one of the support positions. In one refinement of the method, an adapter truck having a truck interface is docked to an adapter station. Herein, a plug connector of the truck interface is automatically plugged into a plug connector of the adapter station, on account of which actuators of the adapter truck are supplied with electricity. Alternatively, for transmitting torque, actuators of the adapter station are docked to mechanical connectors of the truck interface. The adapter truck is adapted to a specimen or a mounting truck in that the supports of the adapter truck, by means of the actuators of the adapter truck, or the actuators of the adapter station, are displaced to positions which are suitable for receiving the specimen or the mounting truck. The specimen now is mounted on the adapter truck. Alternatively, the mounting truck is clamped in a form-fitting manner between the supports. Finally, the adapter truck by way of the truck interface thereof is docked to a test bed. According to one embodiment, the assembly is used for adjusting the predefined coupled position between the specimen and the force generator on the test bed. In one refinement, the receptacle device of the assembly is used for gripping and/or lifting a mounting truck on which the specimen is mounted. According to one embodiment, the assembly is used for adjusting and/or testing forces which are generated by a point machine as a specimen. BRIEF DESCRIPTION Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein: FIG. 1 shows a test bed for checking a point machine, to which the specimen is fixedly screwed; FIG. 2A shows a side view of a test bed having a device for receiving a specimen, in a first vertical adjustment; FIG. 2B shows a side view of the test bed of FIG. 2A , whereby the device has been vertically lowered for receiving the specimen, with a detailed view of a longitudinal support of the device; FIG. 3A shows a front view of the device shown in FIG. 2A ; FIG. 3B shows a front view of the lowered device shown in FIG. 2B , with a detailed view of a longitudinal support; FIG. 3C shows a front view of a device for receiving a specimen, in which the two longitudinal supports have been displaced to dissimilar vertical positions, so as to receive an asymmetric specimen 1 ; FIG. 4A shows a plan view of the test bed and of the device of FIGS. 2A and 3A ; FIG. 4B shows a plan view of the test bed shown in FIGS. 2B and 3B , with a lowered device which is laterally displaced for receiving a specimen, whereby the left longitudinal support is again shown in detail; FIG. 5 shows a front view of a mechanism which is suitable for displacing the supports in a mutually independent manner, both in the horizontal direction and in the vertical direction; FIG. 6 shows a detailed side view of the mechanism of FIG. 5 , which additionally shows a longitudinal support, a specimen, a force generation, and a test bed; FIG. 7A shows a front view of a mounting truck to which a specimen is screwed, whereby the mounting truck is jammed between the longitudinal supports of the device shown in FIGS. 2A to 6 ; FIG. 7B shows a detailed view of the front view of FIG. 7A , illustrating an alternative design embodiment of the clamping connection between longitudinal supports and mounting trucks; FIG. 8A shows additional clamps which by way of dovetail connections are mounted on the longitudinal supports and which apply additional clamping forces to the specimen, in a front view; FIG. 8B shows one of the two clamps of FIG. 8A , in a side view; FIG. 9 shows a plan view of a test bed on which, by means of a horizontal guide, a slide having two mounting spaces for point machines as specimens is displaceable in the horizontal direction; FIG. 10 shows the test bed of FIG. 9 , in which the slide having the mounting spaces has been displaced to the left; FIG. 11 shows a side view of the test bed of FIGS. 9 and 10 , showing a section through the slide and through the horizontal guide; FIG. 12 shows a detailed view of the test bed of FIGS. 9 to 11 , having a protective wall which is mounted on the slide and is conjointly moved; FIG. 13 shows a detailed view of the test bed of FIGS. 9 to 11 , having a protective hood which has been lowered over a test space; FIG. 14 shows a detailed view of the test bed of FIGS. 9 to 11 , a very large specimen being mounted therein; FIG. 15 shows a plan view of an adapter truck having adjustable supports; FIG. 16 shows the adapter truck of FIG. 15 docking to a test bed, in a side view; FIG. 17 shows a detailed view of a truck interface which is adapted for mechanical coupling to a test-bed interface; and FIG. 18 shows an adapter truck which is docked to an adapter station. Unless otherwise stated, identical elements, or elements with equivalent functions, are provided with identical reference signs in the figures. DETAILED DESCRIPTION FIG. 1 shows a specimen 1 , presently a point machine, which is fastened to an adapter plate 15 which is screwed to a test bed 2 . A throw bar 13 is driven by the specimen 1 in a force and motion direction 11 . The throw bar 13 by way of a coupling point 16 is coupled to a force generator 14 , on account of which a force measurement 12 is enabled. The force generator 14 on the test bed is a hydraulic or electric linear drive, for example. FIG. 2A shows a side view of a device for receiving a specimen, which is mounted on a test bed 2 . A force generator 14 which for adjusting and checking forces which are generated by a specimen 1 interacts with the specimen 1 is also located here on the test bed 2 . Furthermore, the force generator 14 may also actively apply tensile forces to the specimen 1 while the latter does not perform any actuation procedures. The specimen 1 is screwed to longitudinal supports 4 which in turn are suspended on a mechanism 3 which is laterally fastened to the test bed 2 . FIG. 2A shows the longitudinal supports 4 in an upper position. FIG. 2B shows a further side view of the exemplary embodiment of FIG. 2A , in which the longitudinal supports 4 have been vertically lowered. FIG. 2B (as also FIGS. 3B and 4B ) also includes a detailed view of the front or left longitudinal support 4 , respectively. A dovetail profile 6 which is screwed into horizontal threaded bores 51 in the longitudinal support 4 is visible in the side view of the longitudinal support 4 in FIG. 2B . FIG. 3A shows a front view of the exemplary embodiment of FIG. 2A , whereby the longitudinal supports 4 are positioned at the upper stop, as in FIG. 2A . The arrows in FIG. 3A indicate that the longitudinal supports 4 are horizontally displaceable in both directions. The spacing between the longitudinal supports 4 is also adjustable. FIG. 3B shows a front view of the exemplary embodiment having longitudinal supports 4 which are lowered in a manner corresponding to FIG. 2B . Lowering the longitudinal supports 4 makes it possible for a specimen 1 which has a larger installation height than the specimen 1 of FIG. 2A or FIG. 3A , respectively, to be mounted. Lowering the longitudinal supports 4 guarantees that the coupling point 16 which is explained in the context of FIG. 1 can be kept stationary. This has the advantage that the position of the force generator 14 and the sensitive measuring sensor assembly for the force measurement 12 shown in FIG. 1 does not have to be moved. It is furthermore guaranteed that the introduction of force by the force generator 14 and of the specimen 1 is at all times performed in the force and motion direction 11 which is shown in FIG. 1 . Since the force generator 14 and the mechanism 3 in mechanical and electrical terms are mutually independent, the longitudinal supports 4 may be displaced to the respective required position without influencing the sensitive measuring sensor assembly and the force generator 14 . FIG. 3B additionally and in an analogous manner to FIG. 2B shows the left longitudinal support 4 in a detailed view, whereby the dovetail profile 6 can be seen again. The latter serves for further fastening elements to be pushed thereonto, in particular the clamps 61 , 62 which are shown in FIGS. 8A and 8B , by way of which specimens 1 having particular dimensions may be additionally fastened. FIG. 3B in the detailed view on the internal side of the longitudinal support 4 shows bolts 7 which serve for adapting a mounting truck 20 , as is shown in FIG. 7A . FIG. 3C shows a front view of a variant of the device of FIGS. 2A to 3B , in which the two longitudinal supports have been displaced to dissimilar vertical positions, so as to receive an asymmetric specimen 1 . FIG. 4A shows a plan view of the device, which corresponds to the front view in FIG. 3A and to the side view in FIG. 2A . Correspondingly, FIG. 4B shows a plan view which corresponds to the side view of FIG. 2B and to the front view of FIG. 3B . It can be seen herein that the longitudinal supports 4 have been displaced to the left, so as to receive a horizontally asymmetric specimen 1 . The left longitudinal support 4 is shown so as to be enlarged in a detailed view also in the plan view in FIG. 4B . Vertical threaded bores 52 into which the specimen 1 may be screwed are visible in the plan view beside the dovetail profile 6 , which has already been explained, and the bolts 7 . The provision of a sufficient number of suitably positioned vertical threaded bores 52 ensures that the specimens 1 may be positioned in a sufficiently flexible manner also in the third dimension which cannot be adjusted by the mechanism 3 . FIG. 5 shows the mechanism 3 of FIGS. 2A to 4B in detail, in a front view. A left transverse slide 8 and a right transverse slide 9 are mounted so as to be horizontally displaceable on an upper transverse-slide guide 111 and on a lower transverse-slide guide 112 . The left transverse slide 8 by means of an upper linear axis 121 is traversed along the horizontal guides 111 , 112 . Accordingly, the right transverse slide 9 by means of a lower linear axis 122 is displaced along the guides 111 , 112 . In a manner corresponding to FIG. 5 , the left transverse slide 8 and the right transverse slide 9 are horizontally displaceable in a mutually independent manner. A left mounting slide 81 which is guided on a left mounting-slide guide 82 and is driven by a left linear axis 83 is mounted on the left transverse slide 8 . The left longitudinal support 4 which is shown in detail in FIGS. 2B, 3B, and 4B , is mounted on the left mounting slide 81 . Accordingly, a right mounting slide 91 which in turn is guided on a right mounting-slide guide 92 and is driven by a right linear axis 93 is mounted on the right transverse slide 9 . The right longitudinal support 4 which has been shown in FIGS. 3A, 3B, 3C, 4A, and 4B , is mounted on the right mounting slide 91 . The linear axes are electric or hydraulic linear drives, linear motors, or linear actuators. Suitable robust linear drives and support constructions are known from fork-lift trucks, for instance, the steel prongs of the latter being readjustable in the horizontal spacing thereof and being vertically displaceable by means of a hydraulic drive. In one alternative design embodiment, the horizontal linear drives and optionally also the vertical linear drives are replaced by manual adjustment devices. In one further alternative design embodiment, only one linear drive is in each case provided for the horizontal and/or vertical displacement of both supports, such that the longitudinal supports 4 may only be displaced in a synchronous manner in the horizontal and/or vertical direction. FIG. 6 shows a side view of the device, corresponding to the front view of FIG. 5 , which has been sectioned at the level of the mechanism 3 . The left transverse slide 8 which is guided on the upper transverse-slide guide 11 and on the lower transverse-slide guide 112 and which is driven by means of the upper linear axis 121 is visible in the side view of FIG. 6 . The left mounting slide 81 on which the left longitudinal support 4 is mounted, is mounted on the left transverse slide 8 . In a manner corresponding to FIG. 6 , testing forces 141 act between the force generator 14 and the specimen 1 , since the specimen as a point machine, in interaction with the force generator 14 , performs simulated point actuation procedures. Additionally, a weight 144 of the specimen acts on the longitudinal support 4 . The upper transverse-slide guide 111 as a first force 142 has to absorb a force which results from both the reaction to the testing forces 141 and to the weight 144 of the specimen 1 . The same applies to the lower transverse-slide guide 112 on which a second force 143 consequently acts. An interface 100 between the entire mechanism and the test bed 2 has to be embodied in a sufficiently robust manner beside the suspension of the transverse-slide guides 111 , 112 , so as to be able to withstand the weight 144 of the specimen 1 plus the reaction to the testing forces 141 . Alternatively to FIG. 6 , the interface 100 may also be implemented above the floor in that the mechanism for displacing the longitudinal supports is screwed directly to the floor. The test bed 2 and the mechanism are separately fastened in this variant. FIG. 6 shows the longitudinal supports 4 in a slightly lowered position. This again guarantees that the coupling point and consequently also the force generator 14 can be kept at a constant defined height on the test bed 2 . FIG. 7 a shows a further front view of the device. A mounting truck 20 by suitable horizontal displacement, presently contraction, of the longitudinal supports 4 is clamped in a form-fitting manner and secured by means of the bolts 7 . Herein, additionally to the arrows shown in FIG. 7A , and as has already been explained above, each of the longitudinal supports 4 is displaceable both in the horizontal direction and in the vertical direction. This results in that the clamped mounting truck 20 may be lifted in its entirety by means of the longitudinal supports 4 . It is also possible for the mounting truck 20 to be initially lifted, for the running frame to be removed, and for the mounting truck 20 to be subsequently displaced in a position which is lower than would be permissible by the running gear. The specimen 1 is fixedly screwed to the mounting truck 20 by way of screws 5 . In order to be employed on the test bed, it is necessary for the receptacle plate of the mounting truck 20 to be sufficiently strong in order to be able to absorb the testing forces explained above and to transfer the latter by way of the longitudinal supports 4 to the mechanism. By contrast, the base of the mounting truck 20 , or the running gear, respectively, does not have to absorb any testing forces since the mounting truck 20 is clamped at the level of the receptacle plate thereof. FIG. 7B shows a detail of FIG. 7A in a deviating embodiment. In a manner corresponding to FIG. 7B , the bolt 7 is not attached to the longitudinal support 4 but to the mounting truck 20 . The longitudinal support 4 in this case has a matching bore, or a recess, respectively, for the bolt 7 . In a manner corresponding to FIG. 7B , mounting the bolt to the longitudinal support 4 is dispensed with should the latter be obstructive in the instance of the specimen 1 being mounted directly on the longitudinal support 4 . FIG. 8A shows a left clamp 61 which is plug-fitted on the dovetail profile 6 of the left longitudinal support 4 and which applies a first clamping force 145 to the specimen 1 which here by means of screws 5 is screwed to the longitudinal supports 4 . In a corresponding manner, a right clamp 62 is plug-fitted on the dovetail profile 6 of the right longitudinal support 4 and applies a second clamping force 146 to the specimen 1 . In a manner analogous thereto, FIG. 8B shows a side view of the left clamp 61 and of the specimen 1 . Specimens 1 which by way of the screws 5 can only be insufficiently fastened or not fastened at all may be fixedly braced on the longitudinal supports 4 by means of the clamps 61 , 62 . This offers the advantage that specimens 1 having unusual dimensions may also be adapted. FIG. 9 shows a plan view of a test bed 2 having a double receptacle which is composed of a slide 30 which is mounted on a test-bed interface 100 . Two receptacles for a point machine, each of the former being composed of two individually adjustable longitudinal supports 4 , are mounted on the slide 30 . A point machine as a specimen 1 is mounted on each of the receptacles. The moving region 37 may be laterally displaced along the test-bed interface 100 , on account of which the right specimen 1 may be displaced to a testing position in front of a force generator 14 of the test bed 2 . In the position shown in FIG. 9 , the left specimen 1 is being tested while the right specimen 1 may be replaced. Adapting to the next point machine may be performed here on the right side by means of the adjustable longitudinal supports 4 . The flexible receptacle of the preceding exemplary embodiments is thus provided twice, whereby both receptacles are mounted on the common slide 30 which is horizontally traversable. On account thereof, the next specimen 1 may already be adapted while the current specimen 1 is still positioned in the testing position, still aligned with the stationary force generation 14 . By attaching the second receptacle so as to be parallel with the first receptacle on the common slide 30 which is horizontally movable, the two receptacles may be rapidly replaced in front of the force generation 14 . The specimen may be changed on that receptacle that in each case is not located in front of the force generation 14 , without impeding testing of the other specimen. The adapting position is located in an alternating manner to the left and to the right of the testing position. Changing of positions may be performed manually or automatically. FIG. 10 shows the double receptacle of FIG. 9 , once the specimen 1 , which has been replaced on the right side of the movable region, has been conjointly displaced with the slide 30 in front of the force generator 14 on the test bed 2 . The testing position henceforth is consequently on the right side, while a new specimen 1 may be mounted in the adapting position on the left side. FIG. 11 shows a side view of the double receptacle. The slide 30 by means of one or a plurality of horizontal guides 33 is connected to the test-bed interface 100 . The horizontal guides 33 must be able to transmit the testing forces which have already been explained in the context of FIG. 6 . The slide 30 by means of a running gear 34 is supported on the ground. The slide 30 herein is mounted on rollers, wheels, or on a rail, for example, the former potentially serving as an additional guide for the horizontal motion. FIG. 12 shows an exemplary embodiment of the double receptacle of FIGS. 9 to 11 , in which the two receptacles are separated by a protective wall 35 as an occupational protection for a technician. FIG. 13 shows an alternative exemplary embodiment in which a protective hood 36 is lowered over the testing position. Both exemplary embodiments serve for excluding any mechanical risk for a technician at the adapting position. FIG. 14 shows a further exemplary embodiment of the double receptacle of FIGS. 9 to 11 , in which a very large specimen 1 is mounted across both receptacles so as to be on three of the longitudinal supports 4 . This permits even very large specimens 1 to be supported and to be adapted to the test bed 2 . FIG. 15 shows a plan view of an adapter truck 22 having two longitudinal supports 4 which by means of the mechanism shown in FIG. 5 , or an equivalent mechanism, may be flexibly adjusted so as to adapt the adapter truck 22 to the individual dimensions of a specimen 1 which is mounted on the longitudinal supports 4 . The adapter truck 22 furthermore includes a truck interface 101 by means of which the adapter truck 22 may be coupled to a test bed or to an adapter station. FIG. 15 shows the potential for the receptacle to be installed on a separate adapter truck 22 . It is meaningful herein for the truck interface 101 , besides a mechanical interface, to be provided with an electrical interface which automatically contacts the mechanism. The adapter truck 22 has to be supplied with electricity only when the specimen 1 is adapted at the adapter station 21 which is shown in FIG. 18 , so that the positions of the longitudinal supports 4 may be adjusted. Since the positions are mechanically latched, the former are maintained even without an electrical supply. In as far as the actuators are disposed in the adapter truck 22 , the adapter station 21 includes the remaining power electronics. Alternatively, the actuators per se may be received in the adapter station 21 such that the necessary motions are transmitted in a purely mechanical manner by way of docking-capable shafts to the four axes of the mechanism of the adapter truck 22 . In this case, the adapter truck 22 is purely passive, and is correspondingly easier and more cost-effective to make. The adapter truck 22 by way of the longitudinal supports 4 may also grip a simple mounting truck on which the specimen 1 is mounted. FIG. 16 shows the adapter truck 22 of FIG. 15 , once the latter has been docked to a test bed 2 . Herein, a mechanical coupling which is to be rapidly closed and to be rapidly opened and which is capable of absorbing the testing forces on the test bed 2 is provided by means of one or a plurality of connections 40 between the truck interface 101 and a test-bed interface 100 . In a manner analogous to the preceding exemplary embodiments, the adapter truck 22 includes adapter axes which are shown as elements of the mechanism 3 in FIG. 5 , for example. By means of these adapter axes the longitudinal supports 4 of the adapter truck 22 are suitable adjusted so as to align the specimen 1 in a highly accurate manner to the force generator 14 on the test bed 2 . FIG. 17 shows a detailed view (plan view) of a truck interface 101 which is adapted for producing a mechanical and electrical connection to a test-bed interface 100 of a test bed. To this end, the adapter truck is first moved along a first motion vector 44 . Subsequently, the adapter truck is moved along a second motion vector 45 , whereupon locking bolts 41 of the test-bed interface 100 are deployed along a third motion vector 45 , mechanically locking the adapter truck in the test-bed interface 100 . This connection is very robust such that the former can absorb the testing forces 141 . An electrical plug 42 is automatically and conjointly plugged into an electrical socket 43 of the test-bed interface 100 when the connection is produced. On account thereof, electrical contacting of the adapter truck and, indirectly, also of a specimen which is mounted on the adapter truck is provided. The uniform socket-plug connection is automatically and conjointly plugged when the adapter truck docks to the test bed or to an adapter station. Alternatively for the electrical integration of the adapter truck, a separate adapter cable may be manually plugged in. In order for a specimen which is mounted on the adapter truck to be electrically contacted, said specimen may initially be plugged into the adapter truck by way of the specific specimen-side cable, which adapter truck in turn by way of the standardized socket-plug interface which is shown in FIG. 17 is automatically contacted at the test bed or at the adapter station. The electrical connection between the test bed and the adapter truck may be utilized in order to be able to reposition the point machine during the testing sequence by means of the longitudinal supports 4 . Instead of the test-bed interface 100 , an interface of the same type may be provided on an adapter station to which the adapter truck docks. FIG. 18 in a side view shows such an adapter station 21 to which the adapter truck 22 , having the truck interface 101 thereof, has docked. The adapter truck 22 at the adapter station 21 may be automatically or manually adjusted to the respective specimen 1 . In the case of automatic adjustment, the adapter station 21 supplies electric power and control signals for the axes of the mechanism of the adapter truck 22 , in order for the two longitudinal supports 4 to be adjusted. Herein, the adapter truck 22 by means of the longitudinal supports 4 may also grip a simple mounting truck on which the specimen 1 is mounted. The adapter truck 22 per se is mounted on wheels which are rotatable by 360°, for example, or on spherical rollers. Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention. For the sake of clarity, it is to be understood that the use of ‘a’ or ‘an’ throughout this application does not exclude a plurality, and ‘comprising’ does not exclude other steps or elements.

A device under test, such as a point machine, which is screwed to two longitudinal supports, which can be individually moved horizontally and vertically is provided. Thus, a highly flexible solution is created, because even devices under test having unknown or asymmetric dimensions can be fittingly accommodated and positioned. Linear drives enable highly accurate positioning of the supports, in particular even if the supports are have high inherent weight or are already loaded with the device under test. According to one embodiment, the mechanical system is designed to grasp and/or to lift a mounting cart by means of the supports, on which mounting cart the device under test is fastened by screwing. This provides the advantage that the device under test can be tested while mounted directly to the mounting cart without separate transferring and screwing of the device under test being required.

RELATED APPLICATIONS The present application is a continuation-in-part of U.S. patent application Ser. No. 08/653,385 filed May 24, 1996, this application is abandoned. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the recovery of oil from subterranean petroleum reservoirs, and more particularly, to an improved surfactant flooding process and composition applicable to alkaline surfactant flooding (ASF) and alkaline surfactant polymer flooding (ASPF) which results in ultra-low interfacial tensions with brine against crude oil even while the surfactant present is at or below its critical micelle concentration (CMC). The alkaline surfactant flooding process is used in oil reservoirs where a primary surfactant system has been diluted with brine and pumped downhole where the alkali, which is usually sodium hydroxide or sodium carbonate, reacts with the residual oil acidic organic component(s) to form a secondary surfactant system. This "in situ" formed secondary surfactant helps the primary surfactant further reduce the interfacial tension between the residual oil and the injected fluid thereby allowing the removal of residual oil from the pores of the reservoir. The present invention utilizes a primary surfactant system which includes anionic surfactant(s), nonionic cosurfactant(s), solvent(s), and strong base. Ultra-low Interfacial Tension Measurements (<10 -2 mN/m) are obtained between the diluted primary injection solution and the residual oil allowing the primary injection solution to permeate the reservoir oil thereby allowing maximum contact between the alkali and the acidic organic component(s) of the residual oil even though concentrations of the surfactants in the diluted primary system may fall to levels at or below the CMC. 2. The Prior Art It is well known that substantial amounts of oil remain in subterranean petroleum reservoirs after primary and secondary recovery processes have been employed. Numerous tertiary means of recovering residual oil have been developed, such as adding various chemicals to an aqueous reservoir flooding medium. These processes have provided improved tertiary oil recovery in selected oil fields with suitable chemical and physical parameters. The prior advances have not supplied an aqueous surfactant system and process which performs well at low surfactant concentrations, or surfactant concentrations at or below its CMC. Additionally, the surfactant used by the prior advances has been found to interfere with the ability of the polymer to increase the viscosity, the surfactant used is rapidly lost through absorption onto the formation, the range of surfactant concentrations where the interfacial tension of the surfactant is ultra-low (<10 -2 mN/m) is too narrow, the temperature range of the surfactant where the interfacial tension is ultra-low (<10 -2 mN/m) is too narrow, the range of alkalinity where the interfacial tension of the surfactant is ultra-low (<10 -2 mN/m) is too narrow, the surfactant is not readily soluble or dispersible in the formation brine, the viscosity of the concentrated surfactants is very high making it difficult to handle during transfer and dilution. The uniqueness of the present invention is that a surfactant formulation has been found which when combined with a solution containing alkali and optionally a polymer allows the alkali to enter the pores of an oil bearing formation by lowering the interfacial tension between the oil and injection solution resulting in intimate contact between the alkali and the residual oil containing acidic organic component(s). This further allows the formation of a secondary surfactant which is formed in situ by the reaction of the injected alkali and the residual oil containing acidic organic component(s). The invention is stable in solutions of the alkali, does not degrade or interfere with the performance of the polymer, and is effective at low concentrations at or below the CMC, and works over a wide range of alkali concentrations. It is very important that the surfactant system work over a broad range of alkali concentrations because the concentration of the alkali and surfactant changes as the alkali is depleted by reactions with residual oil containing acidic organic component(s), and as the alkali and surfactant is diluted with formation brine or adsorbed onto the formation. The surfactant system must be able to function effectively during the concentration changes encountered. Accordingly the inventors have found that these problems and others have been overcome by carefully selecting the optimum mixture of surfactants, solvent(s) and co-surfactant(s), such surfactants being the various products of the sulfonation of alkylaromatics. SUMMARY OF THE INVENTION It is accordingly the object of the invention to provide an improved concentrated surfactant formulation containing primarily a mixture of anionic surfactants which demonstrate ultra-low (<10 -2 mN/m) interfacial tension against crude oils containing acidic organic components over a broad range of surfactant concentrations, electrolyte concentrations, alkali concentrations, temperatures, and furthermore the surfactant(s) being dispersible in formation brine and used at a concentration above, at, or below its CMC. It is a further object of the present invention to provide an improved alkaline surfactant flooding technique wherein the injection fluid comprises the aforementioned concentrated surfactant formulation containing a mixture of anionic surfactants and more particularly the anionic surfactants being formed from the sulfonates of linear and branched dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, and higher chain length alkyl benzenes, and the sulfonates of alkyl naphthalenes, toluene, xylene, and the sulfonatable fraction of oils known as petroleum sulfonates and their metal and amine salts. It is a further object of the present invention to provide an improved alkaline surfactant flooding process wherein the injection fluid contains the above mentioned concentrated surfactant formulation containing a mixture of anionic surfactants which when added to alkaline brine give ultra-low (<10 -2 mN/m) interfacial tension against a crude oil, and which concentrated surfactant formulation may further comprise solvent(s) and nonionic cosurfactant(s) which enhance the ultra-low (<10 -2 mN/m) interfacial tension in the injected fluid. It is a further object of the present invention to provide a method of recovering residual oil found in subterranean oil reservoirs by utilizing the aforementioned improved alkaline surfactant flooding process, where an aqueous polymer may also be used to increase the viscosity of the injection fluid containing an alkali and the concentrated surfactant formulation, either above, at, or below its CMC, which decreases the interfacial tension between the trapped oil and the injection fluid to <10 -2 mN/m allowing the alkali to come in contact with the trapped oil and react with naturally occurring acidic organic component(s) present in the residual oil forming salts having surfactant properties which enable the residual oil to be emulsified or dispersed in the aqueous phase and thus mobilized and brought to the surface. BRIEF DESCRIPTION OF THE TABLES Table 1 Gives examples of formulations used in the development of the invention Table 2 Shows the composition of the brine used in the testing. Table 3 Illustrates a comparison of the interfacial tensions of 0.3% by weight solutions of the surfactant formulation, whose composition is within the scope of this invention, with various concentrations of NaOH, using a University of Texas spinning drop tensiometer and further using a test crude oil and brine whose composition is described in Table 2. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 Illustrates the determination of the CMC of the concentrated surfactant formulation according to this invention. FIG. 2 Illustrates the interfacial tensions for various dilutions of the concentrated surfactant formulation below, at, and above its CMC in the brine described in Table 2 against the test crude oil. FIG. 3 Illustrates the interfacial tensions of the concentrated surfactant formulation, according to this invention, at concentrations between 0.01 and 0.2% and NaOH concentrations between 0.60 and 1.5% by weight in the brine described in Table 2 against the test crude oil. DESCRIPTION OF THE INVENTION While the present invention will be fully described it is to be understood at the outset that persons skilled in the art may modify the invention herein described while still achieving the desired result of the invention. Accordingly, the description which follows is to be understood as a broad informative disclosure directed to persons of skill in the appropriate arts and not as limitations upon the present invention. The present invention utilizes a primary concentrated surfactant system containing (1) a mixture of anionic surfactants, (2) solvent(s), (3) a strong base and (4) optionally a nonionic surfactant or mixture of nonionic surfactants or the sulfate or carboxylate of these nonionic surfactants. The primary surfactant system must provide, preferable, ultra-low interfacial tensions in the range of 10 -3 mN/m in the presence of a broad range of alkali and electrolyte concentrations. The surfactant(s) included in the primary surfactant system is selected from a group of sulfonates derived from linear and branched alkyl benzene, alkyl naphthalenes, alkyl toluene, or alkyl xylene, either alone or in combination in varying concentration where the alkyl group consist of between about C-4 and about C-24 and the resulting sulfonate has an average molecular weight of about 230 and about 600. The sulfonation of the alkylaromatic compounds is carried out by one of the many methods known to the art such as the use of oleum, cold SO 3 /SO 2 , chlorosulfonic acid or sulfur trioxide. It has been found that a blend of the sodium salts of the acids resulting from the sulfonation of branched and linear alkylbenzene or mixtures of branched alkylbenzene, where the alkyl chain ranges from about C-4 to about C-24 gives ultra-low interfacial tension as opposed to using only the linear alkylbenzene, see Table 1. Additionally, the resulting molecular weight has been found to be critical in order to obtain ultra-low interfacial tension and the preferred molecular weight has been found to vary depending on the crude oil of interest. The blend of sulfonated alkyl surfactants are chosen so that they deliver the optimum ultra-low interfacial tension between an alkaline brine and the crude oil of interest. The amount of the alkylaromatic sulfonic acid in the concentrated mixture can range from 40 to about 60 percent by weight while the preferred amount is about 50 percent in the concentrated solution. The alkylaromatic sulfonic acid is neutralized with a strong base, preferable sodium hydroxide, to bring the final pH of the concentrated surfactant to above 7. In addition to providing ultra-low interfacial tensions over a broad range of alkali concentrations, the inventors have found that the selected sulfonate blend also provides ultra-low interfacial tensions at very tow surfactant concentrations. FIG. 1 illustrates the CMC of the sulfonate blend, identified as Example 3 in Table 1, to be about 0.036%. FIG. 2 illustrates ultra-low interfacial tension measurements when the concentration of Example 3 of Table 1 is below, at, and above its CMC. Further, FIG. 3 illustrates ultra-low interfacial tension measurements using various concentrations of the surfactant system, described as Example 3 of Table 1, while also varying the NaOH concentrations between 0.60 and 1.50% by weight. From data such as this, the inventors have found that the surfactant systems of this invention provide ultra-low interfacial tensions below, at and above its CMC which provides significant cost saving over existing surfactant systems. The nonionic surfactant selected as a co-surfactant must exhibit a wide range of low and stable interfacial tensions between the alkaline brine and the crude oil in question. Examples of nonionic surfactants suitable include any number of nonionics, including alkoxylated nonylphenol, alkoxylated dinonylphenol, alkoxylated octylphenol and alkoxylates of various straight and branched alcohols having a carbon chain length of preferably from 8 to about 20 or more carbon atoms. Carboxylated and sulfated derivatives of these nonionics have also been found useful in extending the useful range of low interfacial tensions. The preferred group of nonionic surfactants are nonylphenol ethoxylates having from 2 to 12 moles of ethylene oxide. Table 3, Example 4, shows data obtained using nonylphenol+6EO blended with sulfonated alkylbenzene derived from a mixture of linear and branched alkyl groups. This combination is shown to provide ultra-low interfacial tensions over a broad range of alkali concentration. The amount of the nonionic in the concentrated mixture can range from 0 to about 10 percent by weight and the most preferred concentration was found to be about 3 percent of the concentrated mixture. Solvents may be formulated with the concentrated surfactant solution. Isopropyl alcohol, ethylene glycol, water and a narrow-cut aromatic solvent such as Exxon's AROMATIC-100™ are the preferred solvents. The concentration of the narrow-cut aromatic solvent ranges from about 0 to about 10 percent by weight with a preferred amount of about 5 percent. Other lower carbon chain alcohols could also be utilized in the place of isopropyl alcohol consisting of alkyl alcohols from about 2 to about 8 carbon atoms such as ethanol, n-propyl alcohol, n-butyl alcohol, sec-butyl alcohol, n-amyl alcohol, sec-amyl alcohol, n-hexyl alcohol, sec-hexyl alcohol, etc. Other glycols are also contemplated. The alcohol concentration ranges from 5 to about 30 percent by weight of the surfactant concentrate with a preferred amount of about 20 percent, while the glycol concentration ranges from about 0 to about 10 percent by weight with a preferred amount of about 5 percent. The primary concentrated surfactant system is mixed with alkali, and in some cases aqueous polymer, diluted with water, brine or formation brine and delivered to the formation. The primary surfactant system functions to decrease the interfacial tension between the diluted injection fluid and the residual oil in the formation allowing the injected fluids, containing the alkali, to penetrate into the microporous structure of the formation and ultimately make contact with the trapped oil. The alkali in the injection fluid, once in contact with the residual reservoir oil, reacts with the naturally occurring acidic organic components of the residual oil, forming their respective salts which exhibit surfactant properties. The resulting in situ formation of the secondary surfactants enables the oil to be emulsified and dispersed within the injection fluid. It is important to obtain a primary surfactant formulation which provides ultra-low interfacial tensions (<10 -2 mN/m) over a broad range of alkali (such as sodium hydroxide or sodium carbonate) concentrations. Alkali will be slowly depleted by the in situ reaction, resulting in constant concentration changes. The alkali concentration is also changed by dilution effects with reservoir brine, and by adsorption on the formation. Consequently, the primary surfactant system must be stable in a broad range of alkali concentrations, furthermore the interfacial tension measurements must also remain ultra-low over the same broad range of alkali concentrations. Examples 3, 4, 6 and 7 in Table 1 are examples of concentrated surfactant formulations which have been found to meet the above criteria for lowering the interfacial tension between an alkaline brine solution and crude oil. Table 3 illustrates the ultra-low interfacial tensions measured over a range of alkali concentrations (in this case NaOH) ranging from 0.6 percent to 1.4 percent by weight using the above Examples described in Table 1. Table 3 shows that a primary concentrated surfactant system composed of a sulfonated alkylbenzene wherein only linear alkyl groups are present (Example 1) and the average molecular weight is 230, or a sulfonated alkylbenzene wherein the alkyl group is branched with an average molecular weight of 230 (Example 2), does not provide the preferred ultra-low interfacial tension values. Surprisingly, as illustrated in Table 3, a mixture of linear and branched alkylbenzene sulfonate where the alkyl chain has between about 9 and about 16 carbon atoms and the alkylbenzenes have average molecular weights of about 420 and 230 respectively (Example 3) provides ultra-low interfacial tensions in the presence of a broad concentration range of the alkali. This has also been found to be true for a mixture of linear and branched alkylbenzene sulfonate where the alkyl chain has between about 9 and about 16 carbon atoms and the alkylbenzenes have average molecular weights of about 230 and 420 respectively (Example 6). Also this has been found to be true for a mixture of branched alkylbenzene sulfonates where the alkyl chain has between about 9 and about 16 carbon atoms and the alkylbenzenes have average molecular weights of about 230 and 420 (Example 7). Finally this has also been found to be true for a mixture of linear and branched alkylbenzene sulfonate where the alkyl chain has between about 9 and about 16 carbon atoms and the alkylbenzenes have average molecular weights of about 420 and 230 respectively to which the nonionic surfactant nonylphenol+6EO has been added. (Example 4). In general it has been found that mixtures of two branched alkylaromatic sulfonates or a mixture of branched and a linear alkylaromatic sulfonates, each member of the pair having widely different molecular weights gives lower interfacial tensions than a mixture on two linear alkylaromatics having the same widely differing molecular weights. The latter still gives ultra-low interfacial tensions but the effective range of alkali or surfactant concentration for which the interfacial tensions are ultra-low is narrower. It has also been found that addition of a nonionic surfactant or the sulfonate or carboxylate of a nonionic surfactant can broaden the effective range for which ultra-low interfacial tensions are obtained. During the preparation of diluted injection solutions in addition to the primary surfactant concentrate and the alkali, polymer may be added at a concentration of about 200 ppm to about 1% depending on the reservoir conditions, with a preferred amount of about 1000 ppm in the injection fluid. The polymer must also be compatible with the alkali, the brine and the surfactant. It has been found that polyacrylamide is the preferred polymer. It is contemplated that a primary concentrated surfactant solution will be formulated and shipped to the field where the concentrate is diluted with water, brine or formation brine, alkali and optionally polymer before injecting downhole. TABLE 1______________________________________EXAMPLE 1 2 3 4 5 6 7______________________________________ % BY WEIGHTLAB MW˜230* 50 25LAB MW˜420 25 25 25BAB MW˜230** 50 25 25 25BAB MW˜420 25SOLVENT(S) 41 41 41 38 41 41NaOH 9 9 9 9 9 9NONYLPHENOL + 6EO 3 100______________________________________ *LAB = Linear Alkyl Benzene **BAB = Branched Alkyl Benzene TABLE 2______________________________________SYNTHETIC BRINE SOLUTION______________________________________ CO.sub.3 375.13 mg/L HCO.sub.3 1342.44 mg/L Cl 691.47 mg/L SO.sub.4 4.8 mg/L Ca 16.03 mg/L Mg 7.3 mg/L Na 1212.1 mg/L______________________________________ TABLE 3______________________________________EXAMPLE 1, 2 3, 4, 7 6 5______________________________________CAUSTIC, % IFT, mN/m0.6 >1 <10.sup.-2 <10.sup.-2 >10.8 >1 <10.sup.-3 <10.sup.-3 >11.0 >1 <10.sup.-3 <10.sup.-3 >11.2 >1 <10.sup.-3 <10.sup.-3 >11.4 >1 <10.sup.-3 <10.sup.-2 >1Example 1: Sulfonated Linear Alkylbenzene (alkyl chain C10-C16, Avg. MW = 420)Example 2: Sulfonated Branched Alkylbenzene (alkyl chain C9-C15, Avg. MW = 230)Example 3: Sulfonated Linear/Branched Alkylbenzene Blend (alkyl chain C9-C16, Avg. MW = 230/420)Example 4: Sulfonated Linear/Branched Alkylbenzene Blend (alkyl chain C9-C16, Avg. MW = 230/420) and Nonylphenol + 6EOExample 5: Nonylphenol + 6EOExample 6: Sulfonated Linear Alkylbenzene (alkyl chain C9 C16, Avg. MW = 230/420)Example 7: Sulfonated Branched Alkylbenzene Blend (alkyl Chain C9-C15, Avg. MW = 230/420)______________________________________ Note: C9-C16 Linear or Branched MW = 420 cannot be used alone to give stable formulation

An improved concentrated surfactant formulation and process for the recovery of residual oil from subterranean petroleum reservoirs, and more particularly an improved alkali surfactant flooding process which results in ultra-low interfacial tensions between the injected material and the residual oil, wherein the concentrated surfactant formulation is supplied at a concentration above, at, or, below its CMC, also providing in situ formation of surface active material formed from the reaction of naturally occurring organic acidic components with the injected alkali material which serves to increase the efficiency of oil recovery.

REFERENCE TO RELATED APPLICATIONS The present application is a continuation-in-part of U.S. patent application Ser. No. 10/118,378, filed Apr. 8, 2002, which in turn is a continuation-in-part of U.S. patent application Ser. No. 09/223,482, filed Dec. 30, 1998, now U.S. Pat. No. 6,491,222 which was a continuation-in-part of U.S. patent application Ser. No. 09/048,418, filed Mar. 26, 1998, now U.S. Pat. No. 6,114,712. All of the above-noted applications are hereby incorporated by reference herein. BACKGROUND OF THE INVENTION 1. Field of the Invention The field of the invention relates to electro-optical readers or scanning systems, such as bar code symbol readers, and more particularly to the optical path design in a scanning module for use in applications requiring both single line and raster scanning in a single, compact bar code reader. 2. Description of the Related Art Bar code symbols are formed from bars or elements typically rectangular in shape with a variety of possible widths. The specific arrangement of elements defines the characters represented according to a set of rules and definitions specified by the code or “symbology” used. The relative size of the bars and spaces is determined by the type of coding used as is the actual size of the bars and spaces. The number of characters (represented by the bar code symbol) per unit length is referred to as the density of the symbol. To encode the desired sequence of the characters, a collection of element arrangements are concatenated together to form the complete bar code symbol, with each character of the message being represented by its own corresponding group of elements. In some symbologies, a unique “start” and “stop” character is used to indicate when the bar code begins and ends. A number of different bar code symbologies is in widespread use including UPC/EAN, Code 39, Code 128, Codabar, and Interleaved 2 of 5. In order to increase the amount of data that can be represented or stored on a given amount of surface area, several more compact bar code symbologies have been developed. One of these code standards, Code 49, exemplifies a “two-dimensional” symbol by reducing the vertical height of a one-dimensional symbol, and then stacking distinct rows of such one-dimensional symbols, so that information is encoded both vertically as well as horizontally. That is, in Code 49, there are several rows of bar and space patterns, instead of only one row as in a “one-dimensional” symbol. The structure of Code 49 is described in U.S. Pat. No. 4,794,239. Another two-dimensional symbology, known as “PDF417”, is described in U.S. Pat. No. 5,304,786. Still other symbologies have been developed in which the symbol is comprised not of stacked rows, but of a matrix array made up of hexagonal, square, polygonal and/or other geometric shapes, lines, or dots. Such symbols are described in, for example, U.S. Pat. Nos. 5,2276,315 and 4,794,239. Such matrix code symbologies may include Vericode, Datacode, and MAXICODE. Various optical scanning systems and readers have been developed heretofore for reading indicia such as bar code symbols appearing on a label or on the surface of an article. The readers function by electro-optically transforming the spatial pattern represented by the graphic indicia into a time-varying electrical signal, which is in turn decoded into data which represent the information or characters encoded in the indicia that are intended to be descriptive of the article or some characteristic thereof. Such data is typically represented in digital form and utilized as an input to a data processing system for applications in point-of-sale processing, inventory control distribution, transportation and logistics, and the like. One particularly advantageous type of reader is an optical scanner which scans a beam of light, such as a laser beam, across the symbols. Laser scanner systems and components have generally been designed to read indicia having parts of different light reflectivity, i.e., bar code symbols, particularly of the Universal Product Code (UPC) type, at a certain working range or reading distance from a hand-held or stationary scanner to the symbol or target. In the laser beam scanning systems known in the art, a single laser light beam from a light source is directed by a lens or other optical components along a light path toward a target that includes a bar code symbol on a target surface. The moving-beam scanner operates by repetitively scanning the light beam in a line or a series of lines across the symbol by means of motion of a scanning component, such as the light source itself or a mirror disposed in the path of the light beam. The scanning component may either sweep a beam spot across the symbol and trace a scan line across the symbol, or scan the field of view of a sensor of the scanner, or do both. The laser beam may be moved by optical or opto-mechanical means to produce a scanning light beam. Such action may be performed by either deflecting the beam (such as by a moving optical element, such as a mirror) or moving the light source itself. U.S. Pat. No. 5,486,944 describes a scanning module in which a mirror is mounted on a flex element for reciprocal oscillation by electromagnetic actuation. U.S. Pat. No. 5,144,120 to Krichever, et al. describes laser, optical and sensor components mounted on a drive for repetitive reciprocating motion either about an axis or in a plane to effect scanning of the laser beam. Another type of bar code scanner employs electronic means for causing the light beam to be deflected and thereby scan a bar code symbol, rather than using a mechanical motion to move or deflect the beam. For example, a linear array of closely spaced light sources activated one at a time in a regular sequence may be transmitted to the bar code symbol to simulate a scanned beam from a single source. Instead of a single linear array of light sources, a multiple-line array of individual lasers may also be employed, thereby producing multiple scan lines. Such type of bar code reader is disclosed in U.S. Pat. No. 5,258,605 to Metlitsky, et al. The use of multiple discrete lasers is also described in U.S. Pat. No. 5,717,221. Bar code reading systems also include a sensor or photodetector which detects light reflected or scattered from the symbol. The photodetector or sensor is positioned in the scanner in an optical path so that it has a field of view which ensures the capture of a portion of the light which is reflected or scattered off the symbol, detected, and converted into an electrical signal. In retroreflective light collection, a single optical component, e.g., a reciprocally oscillatory mirror, such as described by Krichever, et al. in U.S. Pat. No. 4,816,661 or by Shepard, et al. in U.S. Pat. No. 4,409,470, both herein incorporated by reference, and U.S. Pat. No. 6,114,712, scans the beam across a target surface and directs the collected light to a detector. The mirror surface usually is relatively large to receive as much incoming light as is possible. Only a small detector is required since the mirror can focus the light onto a small detector surface, which increases signal-to-noise ratio. A variety of mirror and motor configurations can be used to move the beam in a desired scanning pattern. For example, U.S. Pat. No. 4,251,798 discloses a rotating polygon having a planar mirror at each side, each mirror tracing a scan line across the symbol. U.S. Pat. No. 4,387,297 and U.S. Pat. No. 4,409,470 both employ a planar mirror which is repetitively and reciprocally driven in alternate circumferential directions about a drive shaft on which the mirror is mounted. U.S. Pat. No. 4,816,660 discloses a multi-mirror construction composed of a generally concave mirror portion and a generally planar mirror portion. The multi-mirror construction is repetitively reciprocally driven in alternate circumferential directions about a drive shaft on which the multi-mirror construction is mounted. U.S. Pat. No. 6,247,647 describes an arrangement for providing either a multiple line, or a single line, scan pattern by means of a controller. All of the above-mentioned U.S. patents are incorporated herein by reference. In electro-optical scanners of the type discussed above, the implementation of the laser source, the optics, the mirror structure, the drive to oscillate the mirror structure, the photodetector, and the associated signal processing and decoding circuitry as individual components all add size and weight to the scanner. In applications involving protracted use, a large, heavy scanner can produce user fatigue. When use of the scanner produces fatigue or is in some other way inconvenient, the user is reluctant to operate the scanner. Any reluctance to consistently use the scanner defeats the data gathering purposes for which such bar code systems are intended. Thus, a need exists for a compact module to fit into small compact devices, such as electronic notebooks, portable digital assistants, pagers, cell phones, and other pocket appliances, which can serve multiple scanning applications. Thus, an ongoing objective of bar code reader development is to miniaturize the reader as much as possible, and a need still exists to further reduce the size and weight of the scan engine and to provide a particularly convenient to use scanner. The mass of the moving components should be as low as possible to minimize the power required to produce the scanning movement, thereby saving battery power. It is further desirable to modularize the scan engine so that a single module can be used in a variety of different scanning applications, such as a single scan line and a raster scan line pattern. A need exists to develop a particularly compact, lightweight module which contains all the necessary light source, scanner and photosensor components for both applications. A further need exists to permanently visually indicate when a bar code reader has been exposed to mechanical shock. SUMMARY OF THE INVENTION OBJECTS OF THE INVENTION It is an object of the present invention to provide a single module capable of selectable single line or rastering scanning motion of the light beam for use in a bar code reader. A related object is to develop an electro-optical scanning module which is both smaller and lighter in weight than using discrete components, while providing a collector area of at least 20 mm 2 . It is yet a further object to produce a module which may be manufactured conveniently, and at low cost. Another object is to permanently visually indicate when a reader has been exposed to mechanical shock. FEATURES OF THE INVENTION Briefly, and in general terms, the present invention provides an optical scan module including a base; a light source supported by the base, for generating and directing a light beam along a first segment of a first optical path; a first scan assembly in the first optical path including a reciprocally oscillatable, first scan mirror mounted for receiving the light beam and sweeping the beam in a first direction at a first frequency; an optical assembly including a light collector for collecting and re-directing light reflected from a symbol along a second optical path, the second path having an optical axis that is displaced from said first segment of the first optical path; a second scan assembly in the second optical path including a reciprocally oscillatable, second scan mirror mounted for oscillating movement, and operative for receiving the light beam along the second optical path, and for sweeping the beam in a second direction at a second frequency along a third optical path exteriorly of the module; and a sensor supported by the base for detecting the collected reflected light that has been re-directed by the light collector, and for generating an electrical signal corresponding to the detected light intensity. The present invention further provides an optical scanner for reading an optical code symbol having either a one-dimensional or a two-dimensional pattern of different light reflectivity, including a first and a second light source for producing first and second laser light beams; and a scanning assembly for receiving one of the light beams and producing a respective outgoing light beam having either a one-dimensional or a two-dimensional scanning pattern. According to the invention, there is further provided a retroreflective optical scan module, including first and second selectable light sources having different beam characteristics for directing a selected light beam to a symbol to be read, an optical assembly including a light collector which collects and redirects the light reflected from the symbol along an optical path to a sensor, and means for selecting which light source to use depending on whether a one-dimensional or a two-dimensional symbol is being scanned. According to the invention, a breakable link coupled between a mass and a support breaks when an electronic device, such as a bar code reader, is exposed to a mechanical shock above a predetermined limit. According to the invention, there is further provided a small-size optical scan module in the form factor of a substantially rectangular parallelepiped module having dimensions approximately 30 mm×15 mm×7.5 mm. In the first embodiment, on one of the larger sides (i.e., preferably a peripheral side measuring 30 mm×15 mm) there is mounted thereon a light source for emitting a light beam, first and second scanning assemblies for receiving said light beam and for generating therefrom a scanning beam directed to an indicia to be read, a detector, and a collector mirror arranged to receive reflected light and to direct it to the detector. The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. Further features of the invention are set out in the appended independent claims, and further preferred features are set out in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a an exploded, perspective view of an optical scanning module according to the preferred embodiment of the invention; FIG. 2 is a perspective view of the module of FIG. 1 from another viewpoint; FIG. 3 shows a hand-held terminal in which the optical scanning module may be implemented; and FIG. 4 is a perspective view of a mechanical device that may be incorporated into the terminal of FIG. 3 for determining whether the terminal has been subjected to excessive impact. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention relates to bar code readers of the type generally described in the above identified patents and patent applications for reading bar code symbols. As used in this specification and the claims, the term “bar code symbol” is intended to be broadly construed and to cover not only symbol patterns composed of alternating bars and spaces, but also other graphic patterns, such as dot or matrix array patterns, and, in short, indicia having portions of different light reflectivity or surface characteristics that results in contrasting detected signal characteristics that can be used for encoding information and can be read and decoded with the type of apparatus disclosed herein. As a preferred embodiment, we describe the implementation of the present invention in a laser scanning, bar code reading module similar to the module illustrated in FIGS. 1 and 2. The modular device of FIG. 1 is generally of the style disclosed in U.S. Pat. No. 5,367,151, issued to Dvorkis et al., assigned to Symbol Technologies, Inc. and hereby incorporated herein by reference, and also similar to the configuration of a bar code reader commercially available as part number SE 1000 or SE 1200 from Symbol Technologies, Inc. of Holtsville, N.Y. Alternatively, or in addition, features of U.S. Pat. No. 4,387,297 and U.S. Pat. No. 4,760,248 issued to Swartz, et al., or U.S. Pat. No. 4,409,470 issued to Shepard, et al., all such patents being assigned to Symbol Technologies, Inc., may be employed in constructing the bar code reader module of FIG. 1 . These U.S. Pat. No. 4,760,248, U.S. Pat. No. 4,387,297 and U.S. Pat. No. 4,409,470 are incorporated herein by reference. The module 200 shown in FIG. 1 is formed from an integral frame or support or assembly 201 which is generally a rectangular parallelepiped in shape, having a bottom side 202 , side walls 203 , and preferably an open top surface enclosed by a printed circuit board (PCB) 204 on which electrical components may be mounted. A first and a second laser diode 205 , 206 are mounted on the assembly 201 for producing light beams 207 , 208 respectively. The light beams 207 , 208 impinge on a mirror 209 from which they are reflected along path 210 . The mirror 209 directs the beams to mirrors 212 , 211 respectively, and in turn to planar mirrors 214 , 215 , and in turn to mirror 217 , which directs the beams exteriorly of the module 200 in the direction of the target 221 . Although both beams could be directed to the target 221 , it is preferred that only one of the diodes 205 , 206 is selected, as described below, so that only the selected beam from the selected diode is directed to the target. The selected beam forms a spot on the target plane. When the mirror is moved, the spot moves along a line (shown by a line across target 221 in FIG. 1 ), which scans across a bar code symbol. Light is scattered or reflected from the symbol to the mirror 217 . FIG. 1 also depicts a first drive coil and moving mirror assembly 219 which supports the mirror 217 and moves in response to current changes in the first drive coil. FIG. 1 also depicts a second drive coil and moving mirror assembly 220 which supports the mirror 209 and moves in response to current changes in the second drive coil. The laser diodes 205 , 206 are mounted in one corner of the module 200 . The laser diodes may be operated in a continuous “constant power” mode, pulsed, or modulated with different power levels, depending on the specific application. It is also known to provide circuitry to maintain each laser diode at a predetermined output power level using a closed-loop feedback circuit using a monitor photodiode associated with the respective diode. The optical subassembly associated with each laser diode 205 , 206 may include a focusing lens and/or aperture stop of the following lens types, depending on the application: spherically symmetric glass or plastic lenses; aspheric glass or plastic lenses, rotationally symmetric as well as non-rotationally symmetric around the optical axis, such as cylindrical optical elements as well as including gradient index lenses, Fresnel lenses, binary optical lenses, or multilevel binary optical lenses; lens systems where the lens diameter itself acts as a functional aperture stop for the system; or holographic optical elements, including, but not restricted to, Fresnel “zone plate” optics. In an alternative embodiment, the mirror or optical element 209 may be oscillated in the y-direction so as to cause the selected beam to be deflected into a raster scanning pattern as shown in FIG. 2 across a two-dimensional symbol or target 321 . The subassembly or device of FIG. 1 may be implemented in any type of bar code reader, fixed or portable. The light reflected from the symbol 221 is received by the mirror 217 , reflected to the collection mirror 218 , and then directed to a detector 222 (see FIG. 2 ). The detector may be a linear array or one long photodiode mounted on the support 203 . More specifically, reflected light from the indicia is first received by the scanning mirror 217 , which directs it onto a concave surface of the collector mirror 218 . This focuses the light via an aperture 223 and a filter 224 onto the photodetector 222 . The photodetector generates an electrical output signal which is then passed on to suitable electronics on the PCB 204 by an electrical coupling. The scanning mirror 217 is mounted for oscillation about an axis, this being achieved by virtue of the interaction between a permanent magnet and the driven electromagnetic coil 219 . A suitable driving signal is applied to the coil, via the PCB 204 and coil electrical contacts. Although a light masking aperture may be used in front of the photodetector 222 , as shown in FIG. 2, for increasing the depth of focus of the photodetector, the same effect can be achieved without an aperture by appropriately specifying the area of the photodetector 222 itself. The scanner motor drive assemblies 219 and 220 shown in FIGS. 1 and 2 are exemplary, and may be replaced with any type of mechanism for effecting a scanning motion of the selected laser beam in one or two dimensions. For example, the scanner motor drive could comprise any of the configurations disclosed in U.S. Pat. No. 5,581,067 and U.S. Pat. No. 5,367,151, both of which are incorporated by reference herein. In another embodiment, the motor drive used to obtain scanning action is preferably a “taut band element” drive. This type of drive is fully described in, inter alia, U.S. Pat. No. 5,614,706 and U.S. Pat. No. 5,665,954, both of which are commonly assigned herewith and incorporated herein by reference. In essence, the arrangement includes an optical element such as a lightweight mirror mounted on a thin flexible strip (the “taut band”) mounted across an electromagnetic coil. A permanent magnet is attached to the optical element which interacts with a varying magnetic field created when an AC signal is applied to the coil to cause repetitive torsional motion in the flexible strip. As a result, the optical element oscillates, thereby providing scanning motion. A taut band element drive of known type includes a coil, a flexible strip, a mirror and a permanent magnet. The flexible strip can be held against the coil, for example, by a holding annulus. An AC voltage applied to the coil causes torsional oscillation. It will be apparent that this arrangement can replace the arrangement shown generally in FIG. 1 . In another preferred embodiment, the type of motor drive used to oscillate the scan mirror can be a Mylar (trademark) leaf spring supporting an unbalanced mirror assembly. The mirror assembly is mounted to a Mylar leaf spring which flexes as the permanent magnet is driven by the AC coil imparting an oscillating force. Yet a further alternative is a “micro-machined” mirror assembly as discussed in U.S. patent application Ser. No. 08/506,574 and U.S. Pat. No. 08/631,364 according to which the mirror is driven back and forth directly by a suitable electrostatic drive motor, preferably of very small dimension. The preferred laser is a semiconductor laser which is mounted by conventional through-hole techniques on the PCB. The photodiode is preferably an SMD (“surface mounted device”) device as is the AC coil for the Mylar leaf spring motor. This eliminates the need for standoffs and hand-soldering or sockets, as are used on prior art scanners. Typically, the laser will be a standard packaged edge-emitting laser. For minimum cost, the laser focusing is not adjustable, and the laser is simply installed with its mounting flange in contact with a shoulder molded as part of a molded member. This will position the laser accurately enough with respect to a molded focusing lens to provide adequate performance within an inexpensive scanner. The fact that the focusing lens is molded as part of the same component as the shoulder minimizes tolerance build-ups that could otherwise cause improper focusing. The laser is held in place within the molded member by means of ultraviolet-curing cement. Since the plastics material of the molded member is transparent to ultraviolet light, the cement may be cured by shining ultraviolet light through the member into the cavity within which the laser is positioned. Cement may be applied to the laser, or to the molded member, with the laser then being pushed into the cavity until it abuts the positioning shoulder. The assembly may then be exposed to ultraviolet light for a few seconds, thereby curing the cement. If desired for higher performance, this method of retaining the laser also allows for a focusing adjustment to be made. In this case, the laser is gradually slid into the cavity while the output beam is being monitored. When correct focus is achieved, the assembly is exposed to ultraviolet light, thus curing the cement and locking the assembly into place. In the unadjusted assembly, it may be possible to eliminate the cement by spring-loading the laser up against the positioning shoulder, for example, by means of a rubber or foam washer between the PCB and the bottom of the laser. The collector mirror 218 is coated with a reflective coating so that light impinging upon it will be reflected toward the photodetector. This reflective coating may also serve another function. Typically, the coating will be a thin film of metal such as gold, aluminum or chrome. These films are electrically conductive. Accordingly, the film also acts as an electromagnetic interference shield for the photodiode. The use of a surface coating to protect the photodiode enables the usual EMI shield to be dispensed with, thereby eliminating both the cost of a separate shield and the labor to have it installed within the assembly. The coating is preferably electrically grounded. The optical filter is held in place in front of the photodiode, and also entirely surrounds the photodiode, thereby preventing stray light from reaching it. The aperture may be small to limit the field of view of the detector, thereby maximizing ambient light immunity. The aperture needs to be accurately located with respect to the collector mirror 218 , to allow the use of a minimum-sized field of view. Accurate relative positions of the aperture and the collector mirror are easily achieved. Turning now to the drive assembly for the scanning mirror 217 in more detail, the mirror is mounted in conjunction with a permanent magnet which interacts with a magnetic field provided by one or more AC current-driven coils to oscillate the mirror. The mirror is mounted relative to the base via an attachment element which is connected to the mirror by two Mylar springs. The mirror assembly is of the unbalanced type, that is, no counterweights are provided against the mirror mass as considered relative to the point of support. The use of an unbalanced mirror, i.e., one in which no counterweights are provided in the mirror assembly, is particularly suitable in implementation in which the mirror is driven at a speed of greater than 100 scans per second. With an unbalanced mirror, since the attachment points of the mirror to the flexible springs is not the center of mass of the mirror assembly, while the mirror is at rest, gravity will exert a relatively greater force on the side of the mirror assembly having the greater mass, causing the mirror to “droop” on its heavier side and pull on the flexible springs. Of course, the effect of such force depends on the orientation of the scanner with respect to the force vector of gravity. The same “drooping” effect is present when the mirror is scanning at relatively low speeds. Hence, in such applications, the use of a balanced mirror would be preferred. A balanced mirror, however, requires additional mass be added to the mirror, or mirror assembly, which is a drawback in terms of operating design weight and the power requirements. In the embodiment of high speed operation (i.e., at more than 100 scans per second), the material composition, size, shape and thickness of the spring may be appropriately selected to achieve the desired resonant frequency. For example, for operation at approximately 200 scans/second, the selection of a Mylar spring with a thickness of 4 mils is appropriate. For operation at 400 scans/second, a stainless steel spring with a thickness of about 3 mils is preferred. FIG. 3 shows a hand-held terminal 300 in which the optical scanning module of the present invention may be implemented. A window 301 is provided through which the laser beam is emitted. A two-position trigger 302 is operatively connected to the laser diodes 205 , 206 , preferably to a microprocessor that controls electrical power to the diodes. Upon manually depressing the trigger to a first position, one of the diodes is actuated and is operative, for example, to produce a beam spot having a generally elliptical cross-section. Upon manually depressing the trigger to a second position, the other diode is actuated to produce a beam spot having a different, for example, generally circular cross-section. The elliptical spot is desirable for a single line scan for reading a one-dimensional symbol, especially when the elongation of the spot is parallel to the bars of the symbol. The circular spot is desirable for a raster scan for reading a two-dimensional symbol. Rather than a two-position switch, a single trigger can be depressed more than once to toggle between beams. Alternatively, two independent triggers can be used, e.g., one on the right side, and one on the left side of the housing. Alternatively, an automatic sensor can function to detect whether the symbol being read is one-dimensional or two-dimensional and automatically select and activate the appropriate laser diode. The automatic sensor can be rendered in software or hardware. Various applications have been identified in which it is necessary to track the location of a portable computer as it is moved throughout a predetermined area. One such application relates to order picking in warehouses where the display on a portable computer is used to guide an operator around a warehouse to facilitate finding items to be gathered for shipment to a customer. In these applications the portable computer may be hand-held, it may be a wearable computer, it may be mounted to a cart or it might be mounted to a fork lift. Another application relates to determining the location of a shopping cart that carries a portable computer within a supermarket or other large retail establishment. The display of the portable computer in this application is used to guide the shopper to the shelves that carry items on his shopping list, and/or to present special offers or advertisements to the shopper as he/she moves about the store. In this case the system is much more effective if the offers are related to items situated near where the shopper is located. For example, the display might indicate there is a sale on a particular brand of soft drink when the shopping cart carrying the portable computer is moving down the soft drink aisle. Various ways of determining the position of a portable computer have been proposed. Some use triangulation based on signals received by radio frequency (R.F.) beacons located within the building. Others use short range beacons that can only be detected when the portable computer is nearby, so if the beacon is detected it is known that the portable computer is positioned close to the beacon. There have also been optical beacons that transmit optical signals within a small area, so that when these signals are detected by a sensor in the portable computer, it is known that the computer is close to the beacon. The R.F. beacons and the optical beacons both transmit messages identifying themselves, so the portable computer can determine which beacon it is close to. With these systems the computer location can only be located when it is close to a beacon. If it is necessary to know the computer's location anywhere in a large building many beacons may be needed, which may be very expensive. In this situation a triangulation system might be more economical. If it is only necessary to locate when the computer is near a small number of predetermined places within a building, the short range beacon system may be more economical. These short range beacons, which can be either R.F. or optical, as stated above, must be provided with power. They can use batteries which will need to be changed periodically, but no wiring will be necessary to install them. Alternately, the building can be wired to provide power to the beacons eliminating the need to maintain batteries, but the installation becomes much more expensive. A position locating system is needed that can locate a computer anywhere in a building without the need for a large number of short range beacons. The system also needs to be less expensive and to use less power than an R.F. triangulation system so that it doesn't reduce the battery life of the portable computer to an unacceptable degree. It is also desirable to minimize the need to build special infrastructure associated with the positioning system into the building to make installation quick, easy and inexpensive. All of these needs can be met by using small inexpensive accelerometers located inside the portable computer. The outputs from these accelerometers can be used to measure acceleration, changes in direction, etc., so that the computer can keep track of its present location. This is a small inexpensive form of inertial guidance that has been used for military applications. This has become practical for cost sensitive applications today due to the development of low cost accelerometers for automobile air bag actuation. A system such as this can determine its position with reference to a starting position. It is therefore necessary to occasionally calibrate the system by telling it where it is at that moment. This location then becomes the starting location from which it references its location as it moves about the building until the next time it is calibrated again. When the portable computer is mounted on a shopping cart, it can be calibrated each time the cart is moved through the entrance door of the store, when the shopper is beginning his shopping session. An optical or R.F. beacon can be located on or near the door frame that signals the cart to calibrate itself by setting its current location at the known location of the door. It will also be important to calibrate the system with a known direction of travel at that time, so the cart entrance to the store should require that the cart be moved through a narrow gate after passing through the door, at which time a second calibration signal will be received from the gate. The system will then have two calibration points which will determine a line in a known orientation to the rest of the building. The system now knows its location and its direction of travel as the shopping session begins. These two calibration points can also be used to sense when a cart is being moved out of the store, instead of into the store because the points will be passed in the opposite sequence. In practice, the portable computer will carry a map of the store in its memory. It will be able to display its position on the map as it moves around the store. It will also be able to display offers related to items on the store shelves as it moves near to those items, or it can show the shopper how to find items he wishes to purchase. The displayed map can also display small symbols on the map indicating where products with associated offers are located in the store, allowing shoppers to easily locate them. In a warehouse picking application the computer can show the operator how to get to the next item to be picked in the shortest possible time. Both systems can give directions in written step by step form, as well as a route displayed on a map. For example, the display can tell the user to go to the end of the aisle and turn left. When he does that, it can tell him to proceed in that direction until told to turn right, etc. It is possible that inaccuracies in the accelerometers' outputs or rounding off errors in the position calculating electronics can accumulate over time resulting in inaccuracy of position information. This can be improved by intelligent use of the map that is contained in the computer's memory. For example, if the computer thinks that the cart is moving parallel to an aisle, but far enough to one side of the aisle that the cart would have to be partially occupying the same space as the known location of the shelves along the aisle, it can assume that its position determination has become inaccurate and it can reposition its currently determined position toward the center of the aisle by enough to avoid indicating that the cart is out of the aisle. Alternatively, it can simply show the cart moving down the center of the nearest aisle that runs approximately parallel to the cart's present direction of travel. If a cart moving down an aisle is not moving, on the average, parallel to the length of the aisle the directional calibration may be slightly in error. This can also be corrected as the cart moves around the store. The use of strategies of this kind will allow the system to constantly correct for accumulating errors. It is also possible to have one or more additional position calibration points in the store so that when a cart passes one of them its position is automatically recalibrated. In some applications, the user will also have a bar code scanner and will occasionally need to scan items on the shelves nearby. When this happens, it will also give the system an indication of where it is because the location of the item being scanned can be known. The location of scanned items can be stored in the portable computer's memory, or can be stored in a remote computer and accessed over an R.F. network. This system can benefit from the use an electronic compass within the portable computer. This will allow the computer to orient itself with respect to the map of the store and will eliminate the need to calibrate direction by making the cart pass by two calibration points as described above. The system can now be calibrated to a known position by passing by a single calibration point. Directional information will come from the compass. Electronic compasses are used in autopilots for boats and planes, and are also recently being used in cars to give an indication of the direction in which the car is heading. They are becoming inexpensive, they are accurate and use very little battery power. A system as described above can work well with two accelerometers located in a horizontal plane. The two accelerometers will be oriented at right angles to each other. When the system is mounted on a cart it will always be properly oriented with respect to the plane of the floor such that only two accelerometers are needed. For some applications the computer may be hand-held, so it will not always be oriented with the same side up as the user travels around a building. In this case, a third accelerometer oriented orthogonally to the first two accelerometers will be needed. This will allow it to track its position in three dimensions allowing it to locate itself no matter what position it is held in. There are several ways in which the performance of imagers can be improved if accelerometers are included within the scanner housing. Accelerometers mounted on the imaging optics can be used to eliminate the effects of hand jitter allowing longer integration time and minimizing image smear. This allows stopping down the optical system to improve depth of focus. The accelerometers would measure small motions of the scanner in the vertical and horizontal direction (in the plane of the sensor). The optical assembly would be moved in directions opposite the measured motion by magnetic or piezoelectric actuators holding the optics stationary within the moving housing. The actuators could stabilize the entire camera, including the sensor array and its focusing optics, or only the array could be moved. Similar technology is used today to stabilize binoculars. Accelerometers could also be used in a scanner with a single line imaging sensor to expand its capabilities. For example, single line imaging scanners are used today to read two-dimensional codes such as PDF 417 by moving the scanner manually up and down, scanning it across the rows of the symbol while the sensor is automatically scanning horizontally across the columns. This technique cannot be used for other two-dimensional symbologies, such as Data Matrix or QR code. If accelerometers were installed in the scanner to measure vertical and horizontal motion of the scanner housing, their outputs could be used to determine where the scanner was pointing during each scan, allowing an image to be built up out of many individual scans. The data from each scan could be placed in its proper location with respect to the other scans in an array in memory until enough of the whole image existed to decode the symbol. This kind of scanner could also be used for image/signature capture. Accelerometers could be used in a similar way to create an image from a single line or rastering laser scanner, eliminating the distortion created by hand movement during image capture. Another aspect of the present invention is to provide an improved mechanical device for visually indicating when the terminal has been exposed to mechanical shock above a predetermined design limit. See, for example, U.S. Pat. No. 6,186,400 of the Assignee describing the problem and one approach to a solution as depicted in FIG. 7 in such patent. Portable and handheld units have warranty limits with respect to drop and impact forces. It is difficult to detect or verify whether damage done to the unit is due to shock or impact beyond the values specified in the design specification. The device of the present invention shown in FIG. 4 will indicate clearly whether damage has been done to a unit without leaving loose parts that would affect the operation of the unit. Referring to the perspective view of the device 400 shown in FIG. 4, the mass 401 will break off one or both links or notches 402 , 403 when impact is greater than that specified in the design specification. After the breakage, a cover (not shown) will retain the mass 401 within the device 400 so that it will not interfere with normal operation of the unit. The rim 404 serves as a base. The mass 401 swings or moves upon being subjected to a mechanical shock and, if the movement is great enough, the mass breaks its link to the rim 404 . The device 400 will be attached to the inside wall of the unit by the rim 404 , and mounting holes 405 by screws, fasteners, an adhesive or any other means. The device will be molded out of brittle plastic with shock acceleration limits molded into the links. The device may be provided in several different masses or configuration to accommodate products with different specified shock levels. The breakage is a permanent visual indicator that the unit was abused. Another embodiment of the present invention relates to measuring the “percent decode” based on multiple scans of the same symbol. One possible way to measure symbol quality is with percent decode, as is known from bar code verifiers. Such prior art verifiers were placed on a symbol and left there long enough to scan the symbol a multitude of times, for example, a thousand times. The number of decodes that occurred out of the thousand attempts was computed and displayed. Obviously, in a reader, the user cannot wait for a thousand scans to occur because it will make it too sluggish. In addition, unlike a verifier, a hand-held scanner may not be aimed at the symbol when initially triggered, so the first few scans may not be useable for a percent decode calculation. The scanner will have to be able to know when the laser is crossing the entire symbol before scans can begin to be counted in the percent decode calculation. This can be done by waiting until a decode occurs, and than letting the scanner run for a few more scans, to see if the following scans also decode. The scanners according to the present invention will probably be running at three hundred scans per second. If the scanner is run for three more scans after a decode, then we will have four scans across the symbol all together, and it will only take 9.9 ms longer than it took to get a single scan. This short time duration is not perceptible by the scanner operator. We can, however, start the decode beep as soon as the first decode happens, and gather the following three scans during the beep. The number of scans that decode, out of the four attempts can provide a crude percent decode. This is probably good enough resolution for this application. Although percent decode is only meaningful if the scan line is covering the symbol, some measure of symbol quality can be obtained by counting how long the scanner runs (or how many scans are made) before a decode happens. This time will be increased if the operator does not aim the scanner carefully before the trigger pull, allowing the scanner to run for a while before moving the scan line onto the symbol. Even so, a symbol that consistently takes longer than other symbols to decode probably has a problem. If the scanner transmits the number of scans it made along with the decoded data for each symbol to the host computer, the host can keep records of time to decode from each symbol in the store. Poorer symbols will have longer average times to decode. In addition, the decode time on poorer symbols will probably have a larger standard deviation than good symbols. There are other things that one can do that should give the operator some indication of symbol quality. For example, if the scanner has a decoder such as described in U.S. Pat. No. 5,302,812 or U.S. Pat. No. 5,449,893, then it will be possible to determine if the symbol had some large defects that required heavy filtering, or a high digitizer threshold to permit decoding. The decoder can do whatever is necessary to decode the symbol and transmit the decoded data as soon as it can, for the most aggressive decoding. After the decode has occurred, it can go back and examine the data again starting with a low digitizing threshold, and/or a high amplifier bandwidth. If the symbol is decodable under these circumstances, then it is a good quality code. If it does not decode, then a higher threshold or lower bandwidth can be tried until a decode is obtained. A poorer symbol will need a higher threshold or heavier filtering to enable a decode. Some damaged symbols may be impossible to decode with a single scan and may require stitching together symbol fragments from multiple scans. The number of scans needed to obtain all necessary fragments will be an indication of how bad the symbol is. Symbols that require half block stitching to decode are probably more badly damaged than symbols that can be decoded with block decoding. This can be done by counting how many scans it takes to decode after a first block is detected. A digitizer with multiple thresholds can also be used to estimate bar code quality. The decoder can attempt to decode with all thresholds, on successive scans. Symbols that decode on all thresholds are good. Symbols that decode with only two out of three thresholds are not good. Symbols that decode on only one are poor. The decoder will run through the available thresholds until a decode occurs. Then it will use the next two scans to try the other thresholds. This way it can be sure that the scan line is on the symbol for all scans that are used to make a quality judgment. This requires that each symbol be scanned three times (or four times, if four thresholds are used), but at three hundred scans per second, two more scans only takes 6.6 ms. This functionally can also be implemented on a scanner that runs at one hundred scans per second. Gathering two more scans (to attempt decoding with the other two thresholds) after a decode will require an additional 20 ms. The beeper can be activated after the first decode to assure that the scanner does not become sluggish when the quality measuring function is activated. The quality function should be selectable by the user so it can be disabled for customers who do not want to use it. It will be understood that each of the features described above, or two or more together, may find a useful application in other types of scanners and bar code readers differing from the types described above. While the invention has been illustrated and described as embodied in a scan module for an electro-optical scanner or bar code reader, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit and scope of the present invention. In particular it will be recognized that features described in relation to one embodiment can be incorporated into other embodiments as appropriate in a manner that will be apparent to the skilled reader. Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims. What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

A suspension mass is mounted for swinging movement relative to, and extends between, a pair of fixed posts spaced apart from each other on an annular support mounted in a portable electronic device. The mass is connected to the posts through a pair of breakable links.

TECHNICAL FIELD [0001] The present disclosure relates to electronic imaging technology and, more particularly, to a capacitive image sensor utilizing capacitive image pixels that have a two-transistor configuration. BACKGROUND [0002] There are many imaging modalities routinely used today for various types of filmless x-rays and fingerprint sensing. Examples include optical imaging, which is the predominant imaging technique for fingerprints, ultrasonic imaging, and capacitive imaging. For each of the specific imaging techniques there are pros and cons. Optical imaging produces a pattern of light and dark that makes up a visual impression of a fingerprint with components that are easily obtained and inexpensive. However, that visual image produced under optical imaging can be tainted by stray light or surface contamination of the imaging plate. Ultrasonic imaging enables the user to see beneath the skin providing more information as a biometric measure. However, ultrasonic imaging is slow, expensive, bulky, and data intensive. Capacitive imaging is widely used for small size finger print sensors, e.g., line scanners or single finger areas, because of its simple structure. However, for large area finger print scanners, i.e., those having a so-called 4-4-1 format, utilizing capacitive imaging techniques has proven difficult due to unreasonable component costs and difficulties in meeting an optimal signal-to-noise ratio. SUMMARY [0003] A capacitive image sensor of an example embodiment includes a sensor array having capacitive image pixels. Each pixel has a two-transistor configuration including a pixel selection transistor and a source follower transistor. The pixel selection transistor activates the source follower transistor. The source follower is coupled to a variable capacitance that affects an input impedance of the source follower. An AC current source is used to interrogate the activated source follower to determine an output impedance of the source follower. The output impedance is a function of the input impedance and is representative of the nearness of an object. The combination of all output impedances from all pixels is used to create an image of the object. [0004] The variable capacitance varies in accordance with the nearness of the object which is affective in altering capacitance. The sensor and/or pixel may further include a DC current source that is used to set a working bias point for the pixel circuit. The AC current source provides a known amplitude and frequency, and may provide a sinusoidal signal or a square-wave signal. The sensor and/or pixel may be implemented with thin film technology. The sensor may provide a resolution of up to about 1000 ppi (pixels per inch). [0005] A method to obtain an impedance readout from the capacitive image pixel includes activating the source follower transistor with the pixel selection transistor, interrogating the source follower transistor by applying an AC current source to the source follower transistor, and determining an output impedance of the source follower transistor based on the interrogation. Notably, the output impedance is a function of the input impedance and, as such, is representative of the nearness of an object that is capable of affecting the variable capacitance. The method may additionally include measuring the voltage output of the source follower transistor wherein the voltage output correlates to the output impedance. [0006] The above summary is not intended to describe each embodiment or every implementation. A more complete understanding will become apparent and appreciated by referring to the following detailed description and claims in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0007] FIG. 1 is a cross-sectional view of a capacitive touch pattern sensor according to an example embodiment. [0008] FIG. 2 is a block diagram illustrating details of a sensor array according to an example embodiment. [0009] FIG. 3 is a schematic diagram illustrating an active pixel circuit disclosed in an earlier-filed disclosure (PRIOR ART). [0010] FIG. 4 is a schematic diagram illustrating an active pixel circuit according to an example embodiment. [0011] FIG. 5 is a schematic of a source follower circuit, a standard equivalent of the source follower circuit and the derived output impedance of the source follower circuit. [0012] FIG. 6 is a graph illustrating results of a SPICE simulation of a pixel configured as shown in FIG. 4 . [0013] FIG. 7 is a flowchart illustrating a procedure according to an example embodiment. [0014] The figures are not necessarily to scale. Like numbers used in the figures refer to like components. However, it will be understood that the use of a number to refer to a component in a given figure is not intended to limit the component in another figure labeled with the same number. DETAILED DESCRIPTION [0015] The present disclosure relates to touch/proximity pattern sensors such as fingerprint sensors. Generally, fingerprints (and similar patterns, e.g., on hands and feet) are readily accessible biometric indicators that are unique to each person. As a result, computer scanned hand/fingerprint images can be used for purposes such as authentication. For example, a scanning sensor may include a flat surface against which to place the finger (or any scanned object). In response to the contact, the sensor generates an image of the texture/contours of the scanned object. Pattern recognition software can compare metrics of the scanned image to stored metrics, and confirm identity based on a match of the metrics. [0016] There are a number of ways a fingerprint image can be obtained, such as using optical sensors. Embodiments described below use capacitive sensing. Generally, an object that touches a sensing surface will affect the local electrical capacitance of the surface wherever there is contact. While capacitive touch input sensing is widely used to determine coarse indications of contact location (e.g., touchscreens, touchpads), the sensors described herein may be capable of much higher resolution (e.g., on the order of 1000 dpi) than a conventional touch input sensor. It will be understood that, while the embodiments herein may be described in the context of biometric touch sensing, the embodiments and variations thereof may be applicable to other applications and devices. For example, devices such as non-destructive testing imagers may obtain an image based on portions of an object that touch and/or are in relatively close proximity to a contact sensing element. [0017] In reference now to FIG. 1 , a cross-sectional view illustrates a capacitive touch pattern sensor according to an example embodiment. A sensor array 102 is built on top of a substrate 104 (e.g., glass). The sensor array 102 includes a plurality of active pixels 100 , an example of which will be described further below. Generally, each pixel 100 is electrically coupled to sensing pads 106 . The pads 106 are electrically conductive and covered by an insulator layer 108 . The insulator layer 108 may be made from a protecting coating polymer such as Parylene. A conductive object 109 contacting the insulating layer 108 changes a local capacitance at the pads 106 . For example, a fingerprint ridge 112 that is different than another pad 106 directly below fingerprint valley 110 . The capacitance may vary not only based on contact versus non-contact, but may also vary depending on the relative proximity of non-contacting portions. For example, different fingerprint valleys may cause different capacitance due to different distances from a surface of the insulating layer 108 . [0018] In reference now to FIG. 2 , a block diagram illustrates details of a sensor array 102 according to an example embodiment. The sensor array 102 includes a number of individual active pixel elements 100 . Each of these elements 100 are associated with one of a row line 204 and a column line 206 . Generally, to detect an image, each of the row lines 204 may be activated in sequence. Activating a row line 204 causes all elements 100 in the rows to become active (e.g., switching on an enabling transistor). Then each of the column lines (e.g., data lines) 206 is scanned to read the individual elements 100 in the currently activated row. Alternate methods of scanning the elements 100 are known in the art, and the embodiments need not be limited to what is shown in FIG. 2 . [0019] As will be described in greater detail below, the reading of each column line 206 may involve applying to each column line 206 a first voltage level for a first period of time, then switching to a second, lower voltage level for a second period of time. The first voltage level charges the currently read element 100 and the second voltage level causes a current flow via the column line that indicates a sensed capacitance of the element 100 . [0020] In reference now to FIG. 3 , a schematic diagram illustrates an active pixel 100 according to a previously disclosed, prior art embodiment which may be found in U.S. Pat. No. 8,618,865. The active pixel 100 is generally configured as a three-transistor sensor, sometimes abbreviated as a 3 T sensor pixel. The three transistors M 1 , M 2 , M 3 in this diagram are n-type, low-temperature, polycrystalline silicon (Poly-si) thin film transistors (TFTs) although it may be possible to use other types of transistor devices such as metal oxide semiconductor, field-effect transistors (MOSFETs). Transistor M 2 is configured as a reset transistor in response to reset signal G n+1 . When G n+1 is activated, M 2 shorts out high frequency rectifying/detection diode D 1 , allowing sensing junction J 1 to be tied to the biasing voltage of D 1 . By tying the reset transistor M 2 to the enable line of the following row (G n+1 ), the active pixels 100 can be reset without using a separate set of reset lines. In other configurations, M 2 may be reset by another line, such as the preceding row enable (G n+1 ), a separate reset line, a data line Dn of an adjacent column, etc. [0021] As seen in FIG. 3 , two capacitors, C p and C f are coupled to the detection diode D 1 at sensing junction J 1 . The C p component is a parasitic capacitor, having one end coupled to the sensing junction J 1 and the other end at ground. The C f component models the sensed capacitance of the pads and insulating layer (see sensing pads 106 and insulating layer 108 in FIG. 1 ). The effective value of C f may vary from zero (or near zero) to some maximum value (in this example on the order of 10 fF) depending on whether or not an object (e.g., fingerprint ridge) is contacting the insulating layer. As will be described in later detail below, the sensed capacitance can be found based on a ratio of gate capacitance of M 1 (C M1 ) and the sum of C f , C p , and C M1 . [0022] The M 1 transistor is configured as a source follower having its gate tied to the sensing junction J 1 . The output of M 1 is tied to data line Dn when enabling transistor M 3 is switched on in response to enable signal Gn. The transistor M 1 also acts as a charge pump to charge up capacitors C f and C p . This charging occurs during the operation cycle of the pixel 100 , when M 3 is enabled. In one prior art embodiment, the operation cycle is between 50-50 μs. During part of the cycle (charging interval), the potential of data line Dn is brought down to a first voltage level, which causes excess charge built up on gain capacitance C M1 by current flowing through diode D 1 to maintain a stable charge voltage V charge =V diode — bias. [0023] When the data line voltage is returned to its original voltage in a later part of the operating cycle (sensing interval), the charge accumulated on the gate of M 1 during charging interval will be redistributed among C p , C f , and C M1 . The final voltage (V sense ) at the sensing junction J 1 at the end of the sensing interval becomes the input of the source follower M 1 , and the output of M 1 at this interval can be read out on Dn. The difference ΔV between the V charge and V sense potentials can be expressed as ΔV is approximately proportional to C M1 /(C f +C p +C M1 ). Generally, the capacitance C f may be determined by measuring current flow through Dn during the sensing interval. [0024] While the above-described prior art embodiment of the active pixel 100 provides a good signal-to-noise ratio, three transistors and a diode are required to form the active pixel 100 . The result is a scanner that could provide a pixel density of approximately 500 ppi. However, technology requirements are ever-expanding and there is a desire to produce an active pixel with up to double the pixel density, i.e. 1000 ppi. A 1000 ppi pixel density is difficult to achieve using the above-described prior art design without using design rules that would exceed most TFT manufacturer's capabilities. As such, disclosed herein below, is a pixel design for an active pixel wherein only two transistors are required yet a desired 1000 ppi pixel density is substantially achieved and manufacturability is eased. [0025] Referring now to FIG. 4 , an active pixel 300 of an example embodiment is disclosed. The design of active pixel 300 has been streamlined from that of FIG. 3 to eliminate the diode D 1 and the reset transistor M 2 . The remaining transistors comprise a source follower transistor M 1 and a pixel selection transistor M 3 . As seen in FIG. 4 , a series capacitance comprising C 3 and C f is connected to junction J 1 as is capacitor C p . As before, C p represents the parasitic capacitance of the pixel 300 while C f models the sensed capacitance of the pads and insulating layer (see sensing pads 106 and insulating layer 108 in FIG. 1 ). The series capacitance of C f and C 3 , which itself has a value of C x , has a combined capacitive value that may vary from zero (or near zero) to some maximum value, e.g., on the order of about 13.3 fF, depending on whether or not an object (e.g., fingerprint ridge) is contacting or near the insulating layer 108 . The value of C x is essentially the object to imager platen, i.e., substrate 104 , capacitance. [0026] The M 1 transistor of FIG. 4 is configured as a source follower having its gate tied to the sensing junction J 1 . However, because the topology has removed the reset transistor M 2 of the embodiment of FIG. 3 , a DC path is needed for the gate of M 1 . Resistor R 1 provides this path. Resistor R 1 may comprise a semi-insulative layer covering all of the pixels 300 and is tied to supply voltage V cc . In a simulation of the pixel 300 a value of 1e13 Ohms was used for R 1 , however, R 1 may be any value as long as the value is much greater than the impedance of C p at a probing frequency, described further below, of the readout process. [0027] With M 1 operating as the source follower transistor and M 3 operating as the pixel selection transistor, the circuit of FIG. 4 is additionally provided with two current sources I 1 and I 2 . I 1 and I 2 are DC and AC current sources, respectively, that either are implemented at the peripheral of substrate 104 using TFT technology or provided by a readout chip. I 1 is the DC source operating to ensure that a correct working bias point is set. I 2 is the “probing” AC source operating to provide a known amplitude and frequency current to the pixel 300 . Specifically, the output impedance of the source follower M 1 is interrogated by injecting the AC current I 2 and measuring the voltage response which thereby enables a determination of the output impedance of M 1 as a function of its input impedance. The input impedance varies in accordance with the distance of an object from the insulating layer 108 . A standard source follower circuit, equivalent circuit, and the derived output impedance as a function of input impedance are shown in FIG. 5 . [0028] The pixel 300 of FIG. 4 was simulated in a SPICE circuit simulator with typical parameters (I 1 =10 uA, I 2 =5 uA (AC) and 100 KHz), and C x ranging from 1e-16 to 1e-13 F). The results are shown in FIG. 6 , where V o is the AC component at the output node, junction J 1 . Note there is essentially no change of the response V o when the probe current frequency of I 2 is changed from 1 KHz to 100 KHz. [0029] While this simulation was assumed to be a small signal, sinusoidal AC source for simplicity in analysis and simulation, it should be noted that in a non-simulation situation, one may choose to use a digital switching (e.g., large, square wave) implementation to provide a digitally compatible circuit. It should additionally be noted that while the output impedance of the source follower M 1 was interrogated by injecting an AC current and measuring the voltage response, the design of the pixel 300 could be modified to measure resulting AC current with an applied AC voltage. And, although specific component types and respective values are shown in FIG. 4 , one of ordinary skill in the art will appreciate that component types and variables can change from what is shown while still falling within the scope of the claimed invention. For example, the n-channel transistors depicted may be replaced with p-channel transistors with the remainder of the circuit modified as appropriate to accommodate the p-channel transistors. [0030] According to an example embodiment, a plurality of pixels 300 are substituted for pixels 100 and incorporated into an array 102 of pixels such as that shown in FIG. 2 . By scanning each pixel 300 in an active array 102 , measurements of the output impedance of M 1 can be assembled into an image. [0031] In reference now to FIG. 7 , a flowchart illustrates a method according to an example embodiment. Specifically, the flowchart depicts a procedure 400 for obtaining an impedance readout of an active pixel sensor within an array of pixels in accordance with the pixel 300 described above. Initially, a pixel is activated with a pixel selection transistor, per block 402 . The source follower transistor, which is coupled to a variable capacitance, is then interrogated by applying an AC current source to the source follower transistor, per block 404 . The voltage output of the source follower transistor is measured, per block 406 . The output impedance of the active pixel is determined based on the measured voltage output, per block 408 . If there are any additional unread pixels, the above-described process is repeated, per decision block 410 , until all pixels have provided a readout from which an image can be formed. If all pixels have provided a readout, the process is terminated. [0032] Systems, devices or methods disclosed herein may include one or more of the features structures, methods, or combination thereof described herein. For example, a device or method may be implemented to include one or more of the features and/or processes above. It is intended that such device or method need not include all of the features and/or processes described herein, but may be implemented to include selected features and/or processes that provide useful structures and/or functionality. [0033] Various modifications and additions can be made to the disclosed embodiments discussed above. Accordingly, the scope of the present disclosure should not be limited by the particular embodiments described above, but should be defined only by the claims set forth below and equivalents thereof.

A capacitive image sensor includes a sensor array having capacitive image pixels. Each pixel has a two-transistor configuration including a pixel selection transistor and a source follower transistor. The pixel selection transistor activates the source follower transistor. The source follower is coupled to a variable capacitance that affects an input impedance of the source follower. An AC current is source is used to interrogate the activated source follower to determine an output impedance of the source follower. The output impedance is a function of the input impedance and the output impedance is representative of the nearness of an object.

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a contents information output system and a contents information output method that output contents information to a recording medium. [0003] 2. Description of the Related Art [0004] A conventional printing system is capable of printing a plurality of copies of a predetermined document by transmitting print data generated e.g. by a personal computer to a printer. More specifically, to issue certain printed matter, predetermined print contents are generated based on a program for document preparation, for example, and then the print data based on the print contents is transmitted to the printer. The printer interprets the received print data and generates image data for printout. This image data is printed on a print recording medium (display medium) supplied from a feed cassette, for example, whereby the printed matter is issued. [0005] As to the conversion of paper information to electronic information, Japanese Laid-Open Patent Publication (Kokai) No. 2000-285203 discloses an information transmitting method using paper containing an IC chip. In this method, information printed on a sheet of paper is also stored in an IC chip attached to the sheet, and when the same information is copied to another sheet of paper, the information stored in the IC chip is read out and printed on the other sheet. Thus, the method uses paper as an electronic storage medium to distribute, exchange, and store information. [0006] Further, Japanese Laid-Open Patent Publication (Kokai) No. H11-78176 has proposed a printed matter publication management system that prevents unauthorized publication of printed matter. This system is used for management of publication of printed matter, such as marketable securities and literary works. In this system, contents stored in a contents management apparatus are allowed to be printed on a display medium only when it is recognized that the display medium contains valid identification information, which enables management of printed matter having valid identification information. The “identification information” disclosed in the above-mentioned publication includes print information, such as letters and symbols, magnetic information, optical detection information, such as bar codes, and watermark information. [0007] Japanese Laid-Open Patent Publication, (Kokai) No. 2001-134672 discloses a printed matter publication management system which achieves high security using an IC chip for authentication of printed matter. This system is characterized in that a printed matter-authenticating apparatus is off-line, and an authentication key for authenticating an IC chip and a decryption key for decrypting data encrypted by an encryption key are stored in advance to achieve high security. Further, this publication discloses a method of reading identification information of an IC chip attached to a sheet of paper on which contents are to be printed, determining whether or not printing on paper having the identification information has been carried out in the past, and printing the contents specific to the sheet on condition that the printing has not been carried, whereby the same contents are prevented from being printed on different sheets of paper. [0008] Japanese Laid-Open Patent Publication (Kokai) No. 2001-96814 discloses a printer with an RF-ID reading and writing device that prints a visible bar code, readable characters, or the like, on a label, based on data read from an RF-ID tag, whereby even if writing in the RF-ID tag is unsuccessful, the operator can recognize the unsuccessful writing and retry writing. [0009] Conventionally, in general printing systems for printing on paper, sheets on which printing or copying has been carried out are separate from a network or system, which makes it practically impossible to manage printed matter. [0010] Japanese Laid-Open Patent Publication (Kokai) No. 2000-285203 discloses storing contents in IC chips. However, it is considered that management of contents on a network will be dominant for the following reasons: [0011] (1) With the reduction of the size of IC chips for achievement of lower prices in future, it is expected that the memory capacity per one chip will be reduced, which sets a limit to storable contents. [0012] (2) With increased speed and capacity of network transmission, it becomes possible to access contents managed on a network, anytime from anywhere. [0013] (3) Management of access to contents with security is desired. Management of authorization of printing is desired. [0014] From the above, it is expected that the application of sheets of paper containing IC chips storing contents will be limited. [0015] The printed matter publication management system disclosed in the aforementioned Japanese Laid-Open Patent Publication (Kokai) No. H11-78176 is comprised of a medium information management apparatus, the contents management apparatus, a use management apparatus, and a printer, and three elements needed for publication of printed matter, i.e. contents, a print recording medium (display medium), and a printing mechanism, are managed independently of each other, for management of publication of printed matter. This makes it possible to prevent unauthorized publication of printed matter and perform remote printing of important printed matter, such as marketable securities, admission tickets, literary works, membership cards, certificates, and so forth. However, this system is for managing publication of printed matter from a host side, and therefore it is impossible for a user to register or modify contents, or access management information of contents. [0016] Although the aforementioned Japanese Laid-Open Patent Publication (Kokai) No. 2001-134672 discloses the printed matter publication management system for authentication of printed matter, this system is intended to manage publication of printed matter similarly to the printed matter publication management system disclosed in Japanese Laid-Open Patent Publication (Kokai) No. H11-78176, and therefore it is impossible for a user to manage contents. [0017] The printer with an RF-ID reading and writing device, which is disclosed in Japanese Laid-Open Patent Publication (Kokai) No. 2001-96814, is not of a type that prints the print information per se as contents. [0018] Further, none of the above-mentioned publications discloses a method of determining not only whether or not contents information is allowed to output to a recording medium therefor, but also whether or not the contents information designated for output has been registered, and outputting the contents information designated for output to the recording medium, based on the results of the determinations. SUMMARY OF THE INVENTION [0019] It is a first object of the present invention to provide a contents information output system and a contents information output method which are capable of ensuring security in outputting contents information to a recording medium. [0020] It is a second object of the present invention to provide a contents information output system and a contents information output method which are capable of managing a recording medium to which contents information was outputted and the outputted contents information in association with each other. [0021] To attain the first object, in a first aspect of the present invention, there is provided a contents information output system that outputs contents information to an identifiable recording medium, comprising an identification apparatus that identifies a recording medium to which the contents information is to be outputted, a first determination device that determines whether or not output of the contents information to the recording medium identified by the identification apparatus is permitted, a second determination device that determines whether or not the contents information designated for output has been registered, and an output apparatus that outputs the contents information designated for output to the recording medium, based on the determination by the first determination device and the determination by the second determination device. [0022] With this arrangement of the first aspect of the present invention, it is possible to ensure security in outputting the contents information to the recording medium. [0023] To attain the second object, it is preferred that the contents information output system further comprises a management apparatus that controls the contents information outputted by the output apparatus and identification information of the recording medium to which the contents information has been outputted. [0024] With this arrangement of the preferred embodiment, it is possible to manage information of the recording medium to which the contents information was outputted. Therefore, using this management information, it is possible, for example, to easily access print information registered on the network and realize management of publication of printed matter. [0025] More preferably, the determination by the first determination device and the determination by the second determination device are carried out in cooperation with the management apparatus. [0026] Preferably, the output apparatus is responsive to the first determination device determining that the output of the contents information to the recording medium is permitted and the second determination device determining that the contents information designated for output has been registered, for outputting the registered contents information, and the output apparatus is responsive to the first determination device determining that the output of the contents information to the recording medium is permitted and when the second determination device determining that the contents information designated for output has not been registered, for outputting the contents information designated for output. [0027] Preferably, the output apparatus is responsive to the first determination device determining that the output of the contents information to the recording medium is permitted and the second determination device determining that the contents information designated for output has been registered, for outputting the registered contents information, and the output apparatus is responsive to the second determination device determining that the contents information designated for output has not been registered, for not outputting the contents information designated for output, regardless of the determination by the first determination device. [0028] Preferably, the output apparatus is responsive to the first determination device determining that the output of contents information to the recording medium is not permitted, for not outputting the contents information designated for output, regardless of the determination by the second determination device. [0029] Preferably, the contents information output system further comprises an information processing apparatus that designates the contents information for output. [0030] Preferably, the contents information designated for output has already been outputted to the recording medium. [0031] Preferably, the recording medium has a radio section attached thereto, and the identification apparatus identifies the recording medium by reading identification information sent from the radio section. [0032] To attain the first object, in a second aspect of the present invention, there is provided a method of outputting contents information to an identifiable recording medium, comprising an identification step of identifying a recording medium to which the contents information is to be outputted, a first determination step of determining whether or not output of the contents information to the recording medium identified in the identification step is permitted, a second determination step of determining whether or not the contents information designated for output has been registered, and an output step of outputting the contents information designated for output to the recording medium, based on the determination in the first determination step and the determination in the second determination step. [0033] The above and other objects, features, and advantages of the invention will become more apparent from the following detailed description taken in conjunction with the following drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0034] [0034]FIG. 1 is a block diagram showing the arrangement of a contents sharing system using an RF-ID tagged display medium, as the contents information output system according to a first embodiment of the present invention; [0035] [0035]FIG. 2 is a flowchart of a printing process executed by the contents sharing system shown in FIG. 1; [0036] [0036]FIG. 3 is a flowchart of processes executed by apparatuses and devices of the contents sharing system in the printing process; [0037] [0037]FIG. 4 is a block diagram showing the arrangement of a contents sharing system using an RF-ID tagged display medium, as the contents information output system according to a second embodiment of the present invention; [0038] [0038]FIG. 5 is a flowchart of a printing process executed by the contents sharing system shown in FIG. 4; [0039] [0039]FIG. 6 is a flowchart of processes executed by apparatuses and devices of the contents sharing system in the printing process shown in FIG. 5; and [0040] [0040]FIG. 7 is a block diagram showing the arrangement of a contents sharing system using an RF-ID tagged display medium, as the contents information output system according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0041] The present invention will now be described in detail below with reference to the accompanying drawings showing preferred embodiments thereof. [0042] First, a first embodiment of the present invention will be described with reference to FIGS. 1, 2, and 3 . [0043] [0043]FIG. 1 is a block diagram showing the arrangement of a contents sharing system using an RF-ID tagged display medium, as the contents information output system according to the first embodiment. In FIG. 1, reference numeral 100 designates the RF-ID tagged display medium, 101 a network, 102 an RF-ID reader-integrated printing apparatus, 103 a data management apparatus, and 104 a PC (personal computer). The RF-ID reader-integrated printing apparatus 102 , the data management apparatus 103 , and the PC 104 are connected to the network 101 . [0044] The RF-ID tagged display medium 100 includes a tag capable of transmitting an ID number, i.e. identification information stored in an IC chip, to the RF-ID reader of the RF-ID reader-integrated printing apparatus 102 by radio. The tag is fixed to the front or reverse surface of the RF-ID tagged display medium 100 with an adhesive or the like, inserted in the RF-ID tagged display medium 100 , or sandwiched between two or more sheets of the RF-ID tagged display medium. [0045] As the display medium, there may be used any of printable display media in sheet form, including ordinary plain paper, surface-coated paper, photographic paper e.g. for photographs, heat-sensitive paper, diazo photosensitive paper, PET films for overhead projectors, films of resins, such as polyethylene and plastic, and so forth. [0046] The RF-ID reader-integrated printing apparatus 102 is comprised of a network interface (I/F) 105 , a controller 106 , an RF-ID reader section 107 as an RF-ID reader, a printer section 108 , a memory section 109 , and an operating section 110 . [0047] The network interface 105 performs data communication via a communication line. The RF-ID reader-integrated printing apparatus 102 has an IP address assigned thereto, for identification on the network 101 . [0048] The controller 106 controls reading of RF-ID, printing, data communication, data display, data storage, and so forth, that is, controls the overall functions of the printing apparatus 102 operating at a high-speed. [0049] The RF-ID reader section 107 reads the RF-ID tag attached to the RF-ID tagged display medium 100 by radio. The RF-ID reader section 107 is comprised of a processor section that performs control operations and data processing, an RF section that modulates transmit data and encodes received data, and an antenna section that carries out RF communication with the RF-ID tag. [0050] The-printer section 108 includes a printer controller and a print engine, and a printing mechanism to which are applicable the electrophotographic printing method employed e.g. by copying machines and laser beam printers, the ink-jet printing method including the bubble jet (registered trademark) printing method and the piezoelectric printing method, the heat-sensitive/thermal transfer method, the wire dot printing method, etc., in short, all printing methods. [0051] The memory section 109 is used to temporarily store ID information (identification information), contents information associated with the ID information, and management information associated with the contents information during printing, for achievement of high-speed printing and high security. [0052] The operating section 110 is a human interface for giving a print instruction and comprised of a display section and an input section. More specifically, the display section may be a display capable of displaying at least information associated with contents, or a display with a touch panel having a surface thereof formed with a digitizer that can be used for input. Alternatively, the display section may be implemented by simple LED's (light emitting diodes) that are illuminated for indication of a processing status. The input section may be implemented by the touch panel or other devices, such as operating buttons and a voice input device. When the RF-ID reader section 107 detects supply of an RF-ID tagged display medium 100 , the detection signal may be used to give a print instruction. [0053] The RF-ID reader-integrated printing apparatus 102 may have the function of optical reading in addition to the above-mentioned functions, and include a data storage section and a data management section. Further, the RF-ID reader-integrated printing apparatus 102 may be integral with a computer. Furthermore, the RF-ID reader-integrated printing apparatus 102 may be implemented by a multifunction apparatus equipped with multiple functions, i.e. a printer function and any of the functions of a copying machine, a scanner, a facsimile machine, a telephone, and so forth. [0054] The data management apparatus 103 is comprised of a network interface (I/F) 111 , a data-storage section 112 , and a data management section 113 . [0055] The network interface 111 performs data communication via the communication line. The data management apparatus 103 has an IP address assigned thereto, for identification on the network 101 . [0056] The data storage section 112 has a database of ID information of authorized RF-ID tags, and a database storing at least ID information of registered ID's, contents information associated with the ID information, and management information associated with the contents information. [0057] The database of the identification information of the authorized RF-ID tags has such identification information registered therein and updated via the network 101 whenever an RF-ID tagged display medium 100 usable in the contents sharing system of the present embodiment is placed onto the market. This makes it possible to use the RF-ID tagged display medium 100 with guaranteed security and manage the security of the contents in printed form. [0058] In the present embodiment, the registered identification information is intended to mean the ID number of the RF-ID tag of an RF-ID tagged display medium 100 , which has been registered upon printing of contents on the RF-ID tagged display medium 100 . [0059] Further, the contents information associated with the identification information is intended to mean information printed on the RF-ID tagged display medium 100 . In some cases, however, the contents information is intended to mean contents information not printed on the display medium 100 but stored on the network in association with the identification information. When the contents information is such kind of information, only a part of the contents has been printed on the RF-ID tagged display medium 100 , and the information associated with the contents is stored on the network, so that it is possible to access the information, as required, so as to print the information on the RF-ID tagged display medium 100 . When contents are modified, the contents information before the update and the contents information after the update may be both stored in a state associated with each other. [0060] Further, the management information associated with the contents information includes at least contents additional data information, print additional data information, associated identification information, and security information. The contents additional data information includes the author of the contents, software used for preparing the contents, a preparation date, and information of a computer used for the preparation. The print additional data information includes the printing date of the contents, information of a printer used for printing of the contents, the range of printing, printing options, the name of a printer model, a driver version, and print properties. The associated identification information includes an RF-ID tag number attached to the RF-ID tagged display medium 100 used for printing the identical contents, or an RF-ID tag number attached to the RF-ID tagged display medium 100 used for printing modified contents of the identical contents. The security information is information of authorization of access to contents, i.e. information as to permission or inhibition of viewing, modifying, or printing of the contents. [0061] The data management section 113 performs a data storage control process including new registration, additional registration, and modified registration, of data into the data storage section 112 , control of data communication via the network 100 , update of the database of the identification information of authorized RF-ID tags, and so forth. [0062] The RF-ID tagged display medium 100 and the RF-ID reader-integrated printing apparatus 102 perform data communication by radio between the RF-ID tag and RF-ID reader section 107 . [0063] Next, the operation of the contents sharing system using the RF-ID tagged display medium, according to the present embodiment, will be described with reference to FIGS. 2 and 3. [0064] [0064]FIG. 2 is a flowchart of a printing process carried out by the contents sharing system according to the present embodiment, and FIG. 3 is a flowchart of processes executed by apparatuses and devices of the contents sharing system in the printing process. [0065] (1) Verification as to Whether an RF-ID Tag Has Been Authorized [0066] In the case of printing newly prepared contents, after preparation of the new contents, or in the case of printing existing contents, after displaying the contents or designating the file of the same (step S 301 in FIG. 3), the PC 104 gives a print instruction (step S 200 in FIG. 2 and step S 302 in FIG. 3.). Then, the RF-ID reader-integrated printing apparatus 102 reads and confirms an RF-ID tag attached to an RF-ID tagged display medium for printing, using the RF-ID reader section 107 as the RF-ID reader. More specifically, in response to the instruction sent from the PC 104 to the RF-ID reader-integrated printing apparatus 102 , the RF-ID reader-integrated printing apparatus 102 acquires identification information (RF-ID) from the RF-ID tagged display medium 100 through radio communication with the RF-ID tag (step S 201 in FIG. 2 and steps S 311 , S 316 in FIG. 3). [0067] The identification information is sent from the RF-ID reader-integrated printing apparatus 102 to the data management apparatus 103 . The data management apparatus 103 verifies whether or not the ID number as the identification information of the RF-ID tag having been read has been authorized, by comparing the read identification information with stored data of authorized identification information (step S 202 in FIG. 2 and step S 305 in FIG. 3). Then, if the RF-ID tagged display medium 100 has authorized identification information, the process proceeds to the following step (step S 203 in FIG. 2 and step S 306 in FIG. 3), whereas if the RF-ID tagged display medium 100 does not have authorized identification information or if the RF-ID tag does not respond, printing is inhibited (step S 210 in FIG. 2 and step S 312 in FIG. 3). [0068] (2) Verification as to Whether the Contents are New or Have Been Already Registered, and Printing [0069] (2)-1: Contents Are New and Not Registered in the Data Management Apparatus. [0070] Then, it is verified whether or not the contents designated by the print instruction have been registered in the data management apparatus 103 (step S 203 in FIG. 2 and steps S 306 and S 307 in FIG. 3). If the contents designated by the print instruction have not been registered in the data management apparatus 103 , this means that the file designated by the print instruction exists at least on the PC 104 , and hence the PC 104 , when notified by the data management apparatus 103 that the contents have not been registered, accesses the contents designated by the print instruction (step S 303 in FIG. 3) and sends the contents to the RF-ID reader-integrated printing apparatus 102 (step S 304 in FIG. 3). The RF-ID reader-integrated printing apparatus 102 receives the contents designated by the print instruction from the PC 104 (step S 313 in FIG. 3) and prints the new contents on the RF-ID tagged display medium 100 (step S 211 in FIG. 2 and step S 314 in FIG. 3). [0071] (2)-2: The Contents Have Already Been Registered in the Data Management Apparatus, But Are Not Identical to the Registered Data. [0072] This is the case where the contents designated by the print instruction have already been registered in the data management apparatus 103 , but are not identical to the registered data, i.e. the case where the contents already registered have been modified after registration and designated for printing. In other words, this is the case where it is necessary to register the already registered RF-ID information and the new RF-ID information in a state associated with each other, for data management. [0073] In this case, first, the data management apparatus 103 accesses the registered contents (step S 204 in FIG. 2) and checks whether or not the contents have been modified after registration, to thereby determine whether or not the contents designated by the print instruction and the registered contents are identical (step S 205 in FIG. 2 and step S 308 in FIG. 3). Then, if the former contents and the latter contents are not identical, the data management apparatus 103 notifies the PC 104 of the fact. When receiving the notification from the data management apparatus 103 , the PC 104 accesses the contents designated by the print instruction (step S 303 in FIG. 3) and sends the designated contents in the PC 104 to the RF-ID reader-integrated printing apparatus 102 (step S 304 in FIG. 3). The RF-ID reader-integrated printing apparatus 102 receives the designated contents from the PC 104 (step S 313 in FIG. 3) and prints the contents on the RF-ID tagged display medium 100 (step S 212 in FIG. 2 and steps S 314 and S 317 in FIG. 3). After completion of the printing on the RF-ID tagged display medium 100 (step S 315 in FIG. 3), the data management apparatus 103 adds information of the correlation between the registered ID (identifier) and a new ID (identifier) to the registered ID (identifier) (step S 213 in FIG. 2 and step S 310 in FIG. 3), followed by the process proceeding to a step S 208 . [0074] (2)-3: The Contents are Registered in the Data Management Apparatus and Identical to the Registered Data. [0075] This is the case where it is determined in the step S 205 in FIG. 2 and in the step S 308 in FIG. 3 that the contents designated by the print instruction and the registered contents are identical, i.e. the case where the identical contents already registered are to be additionally printed. [0076] In this case, the data management apparatus 103 transmits the registered contents accessed in the step S 204 to the RF-ID reader-integrated printing apparatus 102 (step S 309 in FIG. 3). The RF-ID reader-integrated printing apparatus 102 receives the registered contents from the data management apparatus 103 (step S 313 in FIG. 3) and prints the registered contents on the RF-ID tagged display medium 100 (step S 206 in FIG. 2 and steps S 314 and S 317 in FIG. 3). After completion of the printing on the RF-ID tagged display medium 100 (step S 315 in FIG. 3), the data management apparatus 103 adds the print information of the new ID to the management information of the registered ID within the data management apparatus 103 (step S 207 in FIG. 2 and step S 310 in FIG. 3). [0077] ( 3 ) Data Registration [0078] Then, in association with the ID number as the identification information of the printed RF-ID tagged display medium, the contents and the management information associated with the contents are registered anew in the data management apparatus 103 (steps S 208 and S 310 in FIG. 3), followed by the present process being terminated (step S 209 in FIG. 2 and step S 318 in FIG. 3). [0079] In the data registration process in the step S 310 in FIG. 3, if the contents designated by the print instruction have not been registered (step S 307 in FIG. 3), which corresponding to the above-described case ( 1 ), the ID number of the printed display medium 100 , contents information, and contents management information are registered anew. On the other hand, if the contents designated by the print instruction have already been registered but modified (step S 308 in FIG. 3), which corresponds to the above-described case ( 2 ), the identification information (ID number) of the printed display medium 100 , contents information, and contents management information (including the RF-ID number information of a display medium or display media corresponding to the already registered contents) are not only registered anew, but also the identification information of the newly printed display medium is added to the contents management information associated with the already registered identification information. Further, if the contents designated by the print instruction are already registered, and a duplicate thereof has been prepared (step S 308 in FIG. 3), which corresponds to the above-described case ( 3 ), new registration is not carried out, but information indicative of the preparation of the duplicate is added to the contents management information. [0080] In the present embodiment, when a print instruction for printing contents is given by the PC 104 , an RF-ID tag attached to an RF-ID tagged display medium 100 is checked, and after it is verified that the RF-ID tag has been authorized, it is verified whether or not the contents designated by the print instruction have been registered in the data management apparatus 103 . However, these two verification processes may be executed simultaneously or in the reverse order. [0081] According to the contents sharing system of the present embodiment, information of a printed RF-ID tagged display medium 100 is stored in the data management apparatus 103 on the network 101 , and in the present embodiment, a display medium (paper) having an RF-ID tag formed on the reverse surface thereof is used to print confidential documents to be distributed for briefing at an important meeting in a company, for example. This makes it possible to manage information of printed matter outputted from the network 101 through printing of confidential information on the special display medium (paper). [0082] Next, a second embodiment of the present invention will be described with reference to FIGS. 4, 5, and 6 . [0083] [0083]FIG. 4 is a block diagram showing the arrangement of a contents sharing system using an RF-ID tagged display medium, as the contents information output system according to the second embodiment. In FIG. 4, component elements corresponding to those in FIG. 1 according to the first embodiment are designated by identical reference numerals. [0084] [0084]FIG. 4 is distinguished from FIG. 1 in that the PC 104 is omitted from the arrangement in FIG. 1, and the RF-ID reader-integrated printing apparatus 102 has two RF-ID reader sections 107 a and 107 b. [0085] More specifically, one of the RF-ID reader sections, i.e. RF-ID( 1 ) reader section 107 a reads the identification information of a registered RF-ID tagged display medium 100 a, and the other, i.e. RF-ID( 2 ) reader section 107 b reads the identification information of an RF-ID tagged display medium 100 b for printing of contents. [0086] The RF-ID tagged display mediums 100 a and 100 b and the RF-ID reader-integrated printing apparatus 102 perform data communication by radio between the RF-ID tags and the RF-ID reader sections 107 a and 107 b, respectively. [0087] Next, the operation of the contents sharing system using the RF-ID tagged display mediums, according to the present embodiment, will be described with reference to FIGS. 5 and 6. [0088] [0088]FIG. 5 is a flowchart of a printing process executed by the contents sharing system according to the present embodiment, and FIG. 6 is a flowchart of processes executed by apparatuses and devices of the contents sharing system in the printing process shown in FIG. 5. [0089] The RF-ID reader-integrated printing apparatus 102 gives a print instruction (step S 500 in FIG. 5 and step S 600 in FIG. 6), and reads the identification information of an RF-ID( 2 ) tag attached to the RF-ID( 2 ) tagged display medium 100 b using the RF-ID( 2 ) reader section 107 b as the RF-ID reader, and sends the same to the data management apparatus 103 to thereby verify whether or not the RF-ID( 2 ) tag has been authorized (step S 501 in FIG. 5 and steps S 601 and S 602 in FIG. 6). [0090] Then, the data management apparatus 103 determines whether or not the ID number of the RF-ID( 2 ) tag as identification information thereof sent from the RF-ID reader-integrated printing apparatus 102 has been authorized (step S 502 in FIG. 5 and step S 603 in FIG. 6). [0091] If the ID number of the RF-ID( 2 ) tag has not been authorized, printing by the RF-ID reader-integrated printing apparatus 102 is inhibited (step S 510 in FIG. 5 and step S 604 in FIG. 6). On the other hand, if the ID number of the RF-ID( 2 ) tag has been authorized, the RF-ID reader-integrated printing apparatus 102 reads the identification information of the RF-ID( 1 ) tag attached to the RF-ID( 1 ) tagged display medium 100 a using the RF-ID( 1 ) reader section 107 a and sends the same to the data management apparatus 103 (step S 503 in FIG. 5 and steps S 605 and S 606 in FIG. 6). [0092] Then, the data management apparatus 103 verifies whether or not contents associated with the identification information of the RF-ID( 1 ) tag sent from the RF-ID reader-integrated printing apparatus 102 have been registered (step S 504 in FIG. 5 and steps S 607 and S 608 in FIG. 6). [0093] If it is determined that the contents associated with the identification information of the RF-ID( 1 ) tag have not been registered, access to the contents is inhibited (step S 511 in FIG. 5), whereby the RF-ID reader-integrated printing apparatus 102 is unable to print the same (step S 512 in FIG. 5 and step S 609 in FIG. 6). [0094] If it is determined that the contents associated with the identification information of the RF-ID( 1 ) tag have been registered, the data management apparatus 103 accesses the registered contents (step S 505 in FIG. 5) and transmits the registered contents to the RF-ID reader-integrated printing apparatus 102 (step S 610 in FIG. 6). When receiving the registered contents from the data management apparatus 103 (step S 611 in FIG. 6), the RF-ID reader-integrated printing apparatus 102 prints the received registered contents on the RF-ID( 2 ) tagged display medium 100 b (step S 506 in FIG. 5 and steps S 612 and S 613 in FIG. 6). Then, after completion of the printing (step S 614 in FIG. 6), the data management apparatus 103 registers the data (steps S 507 and S 508 in FIG. 5 and step S 615 in FIG. 6), followed by the present process being terminated (step S 509 in FIG. 5 and step S 616 in FIG. 6). [0095] In the data registration process in the step S 615 in FIG. 6, the fact that new printing has been carried out on the RF-ID tagged display medium with the ID ( 2 ) of the RF-ID ( 2 ) tag added thereto is additionally written in the data management apparatus 103 in association with the ID ( 1 ) of the RF-ID ( 1 ) tag, and at the same time the contents information and the management information associated with the contents are newly registered in the data management apparatus 103 in association with the ID ( 2 ) of the RF-ID ( 2 ) tag. [0096] According to the present embodiment, only by setting a display medium with contents printed thereon in the printing apparatus 102 , a duplicate of the contents can be printed exclusively on a display medium authorized for printing. Moreover, the duplicate can be obtained without degradation in image quality and the fact that printing was carried out is registered for management, so that it is possible to realize a contents sharing system which is strictly managed and easily accessible by a user. [0097] Next, a third embodiment of the present invention will be described with reference to FIG. 7. [0098] [0098]FIG. 7 is a block diagram showing the arrangement of a contents sharing system using an RF-ID tagged display medium, as the contents information output system according to the third embodiment. In FIG. 7, component elements corresponding to those in FIG. 1 according to the first embodiment are designated by identical reference numerals. [0099] [0099]FIG. 7 is distinguished from FIG. 1 in that a plurality of RF-ID reader-integrated printing apparatuses 102 a and 102 b and a plurality of data management apparatuses 103 a and 103 b are connected to the network 101 with respective different IP addresses assigned thereto. [0100] The contents sharing system according to the present embodiment stores contents in the data management apparatuses 103 a and 103 b, as data groups each comprised of ID information, contents information, and management information associated with the contents information. [0101] In the present embodiment, information indicative of an IP address where each data group is stored is added to the data group when a data storage section 112 stores the data group, and the data management apparatuses 103 a and 103 b are allowed to share a data table comprised of ID numbers as identification information and IP addresses, and update the data table as required. [0102] This is the same operation as a DNS server performs on the Internet. [0103] This characterizing function of the present embodiment is performed by the data management apparatuses 103 a and 103 b, but a server management apparatus that manages the data management apparatuses may be additionally provided depending the scale of the network 101 . [0104] In the present embodiment, the data groups each comprised of ID information, contents information, and management information associated with the contents information are normally stored in association with the order of the data management apparatuses optimized as a whole in view of the form of organization, the installation place, and other factors. [0105] According to the contents sharing system of the present embodiment, the use of the RF-ID reader-integrated printing apparatuses 102 a and 102 b connected to the Internet and connected to any desired place makes it possible to utilize the contents sharing system more effectively. [0106] Next, a description will be given of a fourth embodiment of the present invention. [0107] An RF-ID reader-integrated printing apparatus in a contents sharing system according to the fourth embodiment has a function of writing identification information in an RF-ID tag attached to an RF-ID tagged display medium by electromagnetic waves. [0108] This makes it possible to utilize an RF-ID tagged display medium having a capability of writing or rewriting in an IC chip, thereby realizing a contents sharing system protected with a higher security. [0109] For example, when contents are printed on a display medium having an RF-ID tag formed by an IC chip with a part or all of identification information unwritten therein, and registered in the present system, the present contents sharing system is capable of encrypting the identification information. In other words, it is possible to protect an identifier (ID) as an index of contents on the network. Alternatively, when a part or all of the identification information is unwritten, the empty area of the RF-ID tag can be used for authentication. [0110] This makes it possible to identify a person authorized to access the contents. [0111] Further, a user is allowed to set the ID information, which enhances the usability of the present contents sharing system. [0112] The above described embodiments are given as illustrative only of the principles of the present invention, since the spirit and scope of the present invention are not limited to the specific embodiments thereof, and all suitable modifications and equivalents may be regarded as falling within the scope of the invention as defined in the appended claims. [0113] It is to be understood that the object of the present invention may also be accomplished by supplying a system or an apparatus with a storage medium in which a program code of software which realizes the functions of any of the above described embodiments is stored, and causing a computer (or CPU or MPU) of the system or apparatus to read out and execute the program code stored in the storage medium. [0114] In this case, the program code itself read from the storage medium realizes the functions of any of the embodiments described above, and hence the storage medium in which the program code is stored constitutes the present invention. [0115] Further, it is to be understood that the functions of any of the above described embodiments may be accomplished not only by executing a program code read out by a computer, but also by causing an OS (operating system) or the like which operates on the computer to perform a part or all of the actual operations based on instructions of the program code. [0116] Further, it is to be understood that the functions of any of the above described embodiments may be accomplished by writing a program code read out from the storage medium into a memory provided on an expansion board inserted into a computer or in an expansion unit connected to the computer and then causing a CPU or the like provided in the expansion board or the expansion unit to perform a part or all of the actual operations based on instructions of the program code. [0117] Further, the program has only to realize the functions of any of the above-mentioned embodiments on a computer, and the form of the program may be an object code, a program code executed by an interpreter, or script data supplied to an OS (Operating System). Examples of the storage medium for supplying the program code include a RAM, an NV-RAM, a floppy (registered trademark) disk, a hard disk, an optical disk, a magnetic-optical disk, a CD-ROM, a CD-R, a CD-RW, a DVD-ROM, a DVD-RAM, a DVD−RW, or a DVD+RW, a magnetic tape, a nonvolatile memory card, and a ROM. Alternatively, the program may be downloaded via a network from another computer, a database, or the like, not shown, connected to the Internet, a commercial network, a local area network, or the like. [0118] The arrangements and advantageous effects of the above described first to fourth embodiments will be summarized below. [0119] 1. The contents sharing system according to the present invention is comprised of the RF-ID reader-integrated printing apparatus having the function of printing contents information on a display medium with an RF-ID tag and the function of reading identification information of the RF-ID tag through radio communication, and the data management apparatus that manages the contents information in association with the identification information, and the data management apparatus manages the contents information printed on the display medium by the RF-ID reader-integrated printing apparatus in association with the identification information of the RF-ID tag. [0120] With this arrangement 1 , contents information printed on a display medium, the printing history of the contents information, and the existing status and the like of printed matter can be managed, which makes it possible to share printed contents with high security as if the printed contents were also connected to the network. Further, it is possible to easily produce printed matter which a user must take care in respect of security thereof. Furthermore, in preparing a duplicate of printed matter, it is possible to produce the same printed matter as the original without degrading image quality thereof. Moreover, a person in charge of managing contents can view print information of the contents, which enables the person to manage all printed matter associated with the contents. [0121] 2. In the contents sharing system with the arrangement 1 , when the RF-ID reader-integrated printing apparatus prints contents information stored in an electronic information storage medium other than the data management apparatus, on a display medium with the RF-ID tag, the data management apparatus newly stores the contents information in association with the identification information of the RF-ID tag, together with management information associated with the contents information. [0122] With this arrangement 2 , contents information electronically generated by a PC or the like is not registered in the contents sharing system at first. In this case, after the contents are printed on an RF-ID tagged display medium, the identification information, the contents information, and the management information associated with the contents information can be registered in the data management apparatus. [0123] This arrangement 2 enables a user to freely use the security-controlled contents sharing system to handle contents prepared by the user himself/herself. [0124] 3. The contents sharing system with the arrangement 1 includes a rewrite means for rewriting management information associated with the identification information of a first RF-ID tag and that of a second RF-ID tag such that the identification information of the first RF-ID tag and that of the second RF-ID tag can be associated with each other, when the contents information stored in the data management apparatus together with the management information in association with the identification information of the first RF-ID tag is printed on a display medium with the second RF-ID tag. [0125] With this arrangement 3 , a user can produce a duplicate of contents registered in the present contents sharing system on a display medium with an RF ID tag authorized for printing and the fact of production of the duplicate is stored as management information. This makes it possible to grasp the date of production, number of copies, status, history, and so forth of the duplicate, and manage history information of the original display medium and that of its duplicate by associating them with each other. [0126] 4. In the contents sharing system with the arrangement 3 , when printing a duplicate of the contents information stored in the data management apparatus together with the management information in association with the identification information of a third RF-ID tag, on a display medium with a fourth RF-ID tag, the RF-ID reader-integrated printing apparatus reads the identification information of the third RF-ID tag, to thereby print the contents information stored in the data management apparatus in association with the identification information of the third RF-ID tag on the display medium with the fourth RF-ID tag. The rewrite means rewrites the management information associated with the identification information of the third RF-ID tag and that of the fourth RF-ID tag such that the identification information of the third RF-ID tag and that of the fourth RF-ID tag are associated with each other. [0127] With this arrangement 4 , it is possible not only to easily produce a duplicate of printed matter at hand without degradation in image quality thereof, which inevitably occurs when printing is carried out after optical reading by a conventional copying machine, but also to manage the duplicate with high security. [0128] 5. In the contents sharing system with the arrangement 1 , a plurality of data management apparatuses and a plurality of RF-ID reader-integrated printing apparatuses are connected via a network, so that at least data groups each comprised of all the contents information, the management information associated with the contents information, and the identification information of the RF-ID tags, which are stored in the data management apparatuses, can be shared. A desired piece of the contents information can be printed by each of the RF-ID reader-integrated printing apparatuses. [0129] With this arrangement 5 , the present contents sharing system can be realized on an enlarged scale with a plurality of data management apparatuses and a plurality of RF-ID reader-integrated printing apparatuses being connected via a network. That is, the contents information output system on an enlarged scale can be realized in which the plurality of data management systems can share at least the data groups each comprised of all the contents information, the management information associated with the contents information, and the identification information of the RF-ID tags, which are stored in the data management apparatuses. More specifically, this is possible, for example, by providing each data management apparatus with the function of always sharing each ID number as identification information and the IP address of one of the data management apparatuses that stores contents information associated with the ID number, as is the case where IP addresses are shared by DNS servers on the Internet, or alternatively by additionally providing a server, which is similar to a DNS server, for managing ID numbers and the IP addresses of the data management apparatuses storing contents information associated with the ID numbers. [0130] 6. In the contents sharing system according to the present invention, the printing apparatus having the function of printing contents information on a display medium with an RF-ID tag is comprised of a reading means for reading identification information of the RF-ID tag by radio communication, an ID information transmission means for transmitting the identification information of the RF-ID tag read by the reading means to a data management apparatus, a reception means for receiving the contents information from the data management apparatus, a printing means for printing the contents information received by the reception means, and a printing termination notification means for notifying the data management apparatus of termination of a printing process by the printing means. [0131] With this arrangement 6 , it is possible to use an authorized RF-ID tagged display medium, as well as to associate printed contents information and the identification information of the RF-ID tag with each other. [0132] 7. The contents sharing system with the arrangement 6 includes an identification information writing means for writing identification information in the RF-ID tag attached to the display medium, using electromagnetic waves. [0133] With this arrangement 7 , it is possible to use an RF-ID tagged display medium having the function of writing or rewriting in an IC chip, thereby realizing a contents sharing system protected with high security. That is, in addition to the use of the identification information, it is possible to perform encryption or authentication using a write memory area, for security purposes. Further, a functional section for writing in an RF-ID tag may be identical to, integral therewith, or formed separately from a functional section for reading, but it is preferred that these functional sections are identical.

A contents information output system which is capable of ensuring security in outputting contents information to a recording medium. A data management apparatus identifies a RF-ID tagged display medium to which contents information is to be outputted, and determines whether or not output of contents information to the identified display medium is permitted. Further, the data management apparatus determines whether or not the contents information designated by a print instruction is registered, and an RF-ID reader-integrated printing apparatus outputs the contents information designated by the print instruction to the display medium, based on the determination by the data management apparatus.

FIELD OF THE INVENTION The invention relates to copolymers of vinyl aromatic monomers and vinyl phosphonic acid derivatives. More specifically, the invention is a process for making copolymer beads by suspension polymerization and for making foamed articles from the beads. BACKGROUND OF THE INVENTION Expanded foams, particularly polystyrene foams, are widely used in the packaging and construction industries. Unfortunately, flame-retardant polystyrene with acceptable physical properties is difficult to manufacture. Halogenated flame-retardant additives used in flame-retardant polymers can leach out of the foam during burning and liberate harmful hydrogen halide vapors. In addition, many halogenated flame-retardant additives are unacceptable because they interfere with the polymerization, resulting in products that contain an undesirably high level of residual monomer. Chemical incorporation of flame retardants into the polymer backbone can give polymer products with good flame resistance and a reduced tendency to liberate harmful vapors. Unfortunately, ethylenically unsaturated monomers that incorporate flame-retardant moieties, particularly inexpensive, nonhalogenated ones, are in short supply. Copolymers of vinyl phosphonic acid derivatives with olefinic compounds are known, and many variations are described in the patent literature. Thermoplastic, expandable beads of these copolymers useful for making foamed, flame-resistant articles have not been previously described. U.S. Pat. No. 2,439,214 teaches copolymers of α,β-unsaturated phosphonic acids and diesters with mono-ethylenic compounds. The reference shows (Example IV) the bulk copolymerization of dimethyl 1-propene-2-phosphonate with styrene to produce a clear, colorless resin. U.S. Pat. No. 2,743,261 teaches copolymers of α- and β-phosphonate styrenes (diesters) and monoethylenically unsaturated compounds. The copolymers are described as clear, tough, flame-resistant, hard resinous copolymers that can be molded into shaped objects or spun into fibers. The reference shows (Example I) bulk copolymerization of styrene and diethyl 1-phenyl vinyl phosphonate. U.S. Pat. No. 3,726,839 teaches crosslinked polymers of a bis(hydrocarbyl) vinylphosphonate, a polyfunctional ethylenically unsaturated monomer such as divinylbenzene, and optionally a monofunctional vinyl comonomer. The compositions are useful as flame-retardant polymers or as polymer additives. U.S. Pat. No. 3,763,122 teaches copolymers of styrene or acrylamide and phenyl vinyl phosphonic acids useful for improving the burst strength of paper. U.S. Pat. No. 3,991,134 teaches copolymers of bis(hydrocarbyl) vinylphosphonates with halogen-containing α,β-ethylenically unsaturated (vinyl) monomers. The reference teaches that mono(alkyl) acid vinylphosphonates can also be used. U.S. Pat. No. 3,993,715 teaches a process for making fire-retardant polymers of bis(hydrocarbyl) vinyl phosphonates. A monoethylenically unsaturated monomer is added as a chaser to complete reaction of the phosphonate monomer. U.S. Pat. No. 4,035,571 teaches copolymers of a bis(hydrocarbyl) vinylphosphonate, a monomer having one ethylenically unsaturated bond, and acrylic or methacrylic acid. The compositions are useful in coatings or as flame-retardant additives for thermoplastics. The reference teaches that these copolymers may be prepared by aqueous suspension polymerization. As shown in Example 2 of the reference, unreacted phosphonate monomer is recovered from the polymerization reaction mixture if the acrylic monomer is omitted. U.S. Pat. No. 4,444,969 teaches copolymers of a vinyl-substituted aryl hydrocarbon monomer, an imide derivative of a cyclic anhydride, and a bis(hydrocarbyl) vinylphosphonate. The solid compositions are useful as fire-retardant additives. A number of papers in the Russian literature describe the preparation of copolymers of α-phenylvinylphosphonic acid (PvPA) with vinyl monomers such as methyl methacrylate and styrene. Spherical granules useful as ion exchangers can reportedly be prepared by suspension polymerization if a crosslinking agent such as divinylbenzene is included (See, for example, Plast. Massy, No. 8 (1966) 24, Plast. Massy, No. 2 (1966) 17, Chem. Abstr. 72 32299g, Chem. Abstr. 83 132379d, and Chem. Abstr. 83 60019m). Such crosslinked copolymer beads are not expandable and therefore not suitable for use in the preparation of foamed articles. The radical copolymerization of dialkylvinyl phosphonates with styrene and methyl methacrylate was studied by Levin et al. (Polym. Sci. USSR 24 (1982) 667). A recent paper (Macromolecules 22 (1989) 4390) describes a copolymer including a vinylphosphonic acid monoalkyl ester. Monoalkyl esters of this type have been prepared by basic hydrolysis of the corresponding diesters in dioxane (J. Organometal. Chem. 12 (1968) 459). None of the references teaches a process wherein vinyl aromatic monomers and vinyl phosphonic acids are copolymerized in the absence of a crosslinking agent to give thermoplastic polymer beads. In addition, none of the above references teaches a process for the preparation of foamed articles from thermoplastic expandable copolymer beads made by suspension copolymerization of a vinyl aromatic monomer and a vinyl phosphonic acid derivative. SUMMARY OF THE INVENTION The invention is a process for making a foamed thermoplastic article. The process comprises molding foamed beads prepared by thermally expanding thermoplastic polymer beads. The thermoplastic polymer beads are made by copolymerizing in an aqueous suspension a vinyl aromatic monomer and a vinyl phosphonic acid or a vinyl phosphonate mono- or diester. The beads are impregnated with a foaming agent either during or following polymerization. As will be shown, the success of the suspension copolymerization of the vinyl aromatic monomer and vinyl phosphonic acid derivative in forming satisfactory polymer beads depends on many factors, including which phosphonic acid derivative is involved. The invention also relates to a process for making expandable thermoplastic beads. The beads are prepared by copolymerizing in an aqueous suspension: (a) a vinyl aromatic monomer, and (b) a vinyl phosphonic acid in the presence of partially hydrolyzed polyacrylamide and at least about 5 weight percent of an alkali metal halide or alkaline earth metal halide salt based on the amount of water used. Another process of the invention comprises copolymerizing in an aqueous suspension: (a) a vinyl aromatic monomer, and (b) a vinyl phosphonic acid in the presence of partially hydrolyzed polyacrylamide and a tetraalkylammonium salt. Another process of the invention comprises copolymerizing in an aqueous suspension: (a) a vinyl aromatic monomer, and (b) a vinyl phosphonate diester in the presence of a high-temperature radical initiator. Another process of the invention comprises copolymerizing in an aqueous suspension: (a) a vinyl aromatic monomer, and (b) a vinyl phosphonate monoester in the presence of partially hydrolyzed polyacrylamide. The monoester can be conveniently generated in situ from the corresponding diester. Another process of the invention comprises copolymerizing in an aqueous suspension a vinyl aromatic monomer and a vinyl phosphonic acid or a vinyl phosphonate mono- or diester in the presence of a foaming agent and a wax to produce expandable thermoplastic polymer beads. DETAILED DESCRIPTION OF THE INVENTION Suspension copolymerization of vinyl aromatic monomers and vinyl phosphonic acids is complicated by the fact that the phosphonic acids usually have greater solubility in water than in the vinyl aromatic monomer. For this reason it is difficult to prepare copolymers having greater than about 1% of recurring units of vinyl phosphonic acids using conventional methods. By including an alkali metal halide salt, an alkaline earth metal halide salt, or a tetraalkylammonium compound in the aqueous suspension polymerization, the proportion of vinyl phosphonic acid that is chemically incorporated into the polymer can be dramatically increased compared with when the same process run in the absence of the salt or tetraalkylammonium compound. Vinyl aromatic monomers useful in the processes of the invention include all aromatic ring-containing compounds that have a vinyl or α-substituted vinyl group attached to the aromatic ring. Suitable vinyl aromatic compounds include, but are not limited to, styrene, alkyl-substituted styrenes, α-methylstyrene, alkyl-substituted α-methylstyrenes, tert-butylstyrenes, nuclear methyl styrenes, halogenated styrenes, vinyl naphthalene, and the like, and mixtures thereof Styrene is the preferred vinyl aromatic monomer. Vinyl phosphonic acids useful in the processes of the invention have the general structure: ##STR1## wherein A is selected from the group consisting of hydrogen and C 1 -C 30 alkyl, aryl, and aralkyl groups. Preferably, A is selected from the group consisting of hydrogen, methyl, ethyl, propyl, butyl, and phenyl. Examples of suitable vinyl phosphonic acids include, but are not limited to, vinyl phosphonic acid, α-phenylvinyl phosphonic acid, α-methylvinyl phosphonic acid, and the like, and mixtures thereof. α-Phenylvinyl phosphonic acid is preferred. The radical polymerization catalysts useful in the processes of the invention are any of the peroxide and azo-type initiators well known to those skilled in the art. Generally, the preferred initiators will have a half-life at the reaction temperature greater than about 1 hour. Suitable examples include, but are not limited to, benzoyl peroxide (BPO)-, tert-butyl perbenzoate (TPB), tert-butyl peroxide, azobis(isobutyronitrile), and the like, and mixtures thereof. (Any amount of initiator may be used, although it is preferred to use an amount greater than about 0.05 weight percent based on the weight of monomers used. Preferably, the initiator is benzoyl peroxide, and the polymerization is conducted at about 90° C. Also preferred is the use of tert-butyl perbenzoate either alone or in combination with benzoyl peroxide at polymerization temperatures within the range of about 80° C. to about 150° C. Partially hydrolyzed polyacrylamide is the only satisfactory suspending agent for suspension copolymerization of vinyl aromatic monomers and vinyl phosphonic acids. Conventional suspending agents such as tricalcium phosphate (TCP), TCP/polyvinyl alcoho (PVA), PVA, barium sulfate, kaolin, and hydroxyethylcellulose generally do not give polymer beads. Partially hydrolyzed polyacrylamide is available from Allied Colloids, Inc., under the tradename "Percol," and from NALCO under the tradename "NALCO-8173." Any effective amount of partially hydrolyzed polyacrylamide can be used. An "effective amount" means, in this context, the amount needed to maintain a stable suspension during the polymerization. Generally, at least about 0.1 weight percent of partially hydrolyzed polyacrylamide based upon the weight of monomers is used. In one process of the invention, the polymerization of a vinyl aromatic monomer and a vinyl phosphonic acid is performed in the presence of an alkali metal salt or an alkaline earth metal salt. Preferred salts are the alkali metal halides. Any amount of salt can be used, but at least about 5 weight percent based on the amount of water used is needed. Preferably, the amount used is within the range of about 15 to 35 weight percent. This amount is needed to produce copolymers that have greater than about 1 mole percent of vinyl phosphonic acid monomer incorporated into the copolymer. Particularly preferred is a range of about 20 to about 30 weight percent of salt Suitable alkali metal halide salts have the general formula MX, wherein M is a monovalent cation selected from the group consisting of lithium, sodium, and potassium, and X is a halide ion. Examples of suitable alkali metal salts include, but are not limited to, sodium chloride, potassium chloride, lithium bromide, potassium fluoride, sodium iodide, sodium bromide, potassium bromide, and the like, and mixtures thereof. Particularly preferred are sodium chloride, sodium bromide, potassium chloride, and potassium bromide. Suitable alkaline earth metal halide salts have the general formula NX 2 , wherein N is a divalent cation selected from the group consisting of calcium and magnesium, and X is a halide ion. Examples of suitable alkaline earth metal halide salts include, but are not limited to, calcium chloride, magnesium bromide, magnesium fluoride, calcium iodide, and the like, and mixtures thereof. Generally, the amount of salt used and the identity of the salt impact the degree of vinyl phosphonic acid incorporation in the polymer and also affect the bead size. Potassium bromide, for example, gives relatively large beads, while calcium chloride and lithium chloride give small beads. Thus, by selecting the proper salt, one can readily control the approximate size of the resulting polymer beads. By controlling the amount of salt added, one can easily control the proportion of vinyl phosphonate monomer that becomes incorporated into the copolymer. Generally, greater salt concentrations enhance vinyl phosphonate incorporability. In another embodiment of the invention, a vinyl aromatic monomer and a vinyl phosphonic acid are copolymerized in an aqueous suspension that includes a tetraalkylammonium compound. Partially hydrolyzed polyacrylamide is required as the suspending agent. An advantage of the tetraalkylammonium compounds is that small amounts are effective in producing copolymers with high vinyl phosphonic acid monomer incorporation. The tetraalkylammonium compounds useful in the process of the invention preferably have the general structure R 4 NX wherein each R group separately represents a C 1 -C 24 alkyl or aralkyl group, and X is a hydroxide or halide ion. Examples of suitable tetraalkylammonium compounds include, but are not limited to, tetramethylammonium hydroxide, tetra-n-butylammonium hydroxide, n-hexyl-tri-n-butylammonium hydroxide, tetra-pentylammonium hydroxide, tetra-isobutylammonium hydroxide, tetra-n-butylammonium bromide, tetrapentylammonium chloride, tetrahexylammonium chloride, and the like, and mixtures thereof. Any amount of tetraalkylammonium compound can be used. For reasons of effectiveness and economy, it is preferred to use an amount within the range of about 0.05 to about 1 equivalent of tetraalkylammonium compound per equivalent of vinyl phosphonic acid monomer. A particularly preferred range is about 0.1 to about 0.8 equivalents. Most preferred is the range from about 0.2 to about 0.4 equivalents. When the vinyl phosphonic acid monomer is α-phenylvinyl phosphonic acid, it is preferred to use a tetraalkylammonium compound having C 4 to C 6 alkyl groups. The tetraalkylammonium hydroxide compound can be prepared in situ from the reaction of a tetraalkylammonium halide salt and a source of hydroxide ions. For example, tetra-n-butylammonium hydroxide is generated in situ by combining tetra-n-butylammonium bromide and sodium hydroxide. In one process of the invention, for example, about 0.2 equivalents of a mixture of tetra-n-pentylammonium bromide and tetra-n-hexylammonium chloride is combined with from about 0.2 to about 0.25 equivalents of sodium hydroxide per equivalent of vinyl phosphonic acid monomer. Copolymers of vinyl aromatic monomers and vinyl phosphonic acids made in the presence of tetraalkylammonium compounds contain a proportion of polymer in which a vinyl phosphonic acid proton is replaced by a tetraalkylammonium group. In another process of the invention, thermoplastic polymer beads are prepared by copolymerizing in an aqueous suspension a vinyl aromatic monomer and a vinyl phosphonate diester. The reaction is performed in the presence of a suspending agent and a radical initiator. In contrast to vinyl phosphonic acids, the suspending agent used for polymerizations with vinyl phosphonate diesters is not especially critical. Any of a variety of well-known suspending agents can be used. Suitable examples include, but are not limited to, partially hydrolyzed polyacrylamide, polyvinyl alcohol, kaolin, tricalcium phosphate, hydroxyethyl cellulose, and the like, and mixtures thereof. The initiator used to copolymerize vinyl phosphonate diesters is preferably a high-temperature initiator. Suitable high-temperature initiators are compounds that have a half-life of greater than about 1 hour at temperatures greater than about 110° C. Examples of suitable high-temperature initiators include tert-butyl perbenzoate (TPB), 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane, and the like, and mixtures thereof. A low-temperature initiator such as benzoyl peroxide may be used in combination with the high-temperature initiator if desired. The vinyl phosphonate diesters useful in the process of the invention preferably have the structure: ##STR2## in which A, R, and R' separately represent monovalent radicals selected from the group consisting of hydrogen, C 1 -C 30 alkyl, aryl, and aralkyl. The vinyl phosphonate diesters are alternatively cyclic vinyl phosphonate esters having the structure: ##STR3## wherein A is as described above, and B is a linear or branched divalent hydrocarbyl radical. Particularly preferred are cyclic diesters in which B is selected from the group consisting of: --CH 2 --CH 2 --and ##STR4## When the process of the invention is performed with vinyl phosphonate diesters, it is preferred to use high-temperature initiators and reaction temperatures greater than about 110° C. Copolymers can be prepared at lower temperatures, but satisfactory beads often cannot be made. In another process of the invention, thermoplastic polymer beads are prepared by copolymerizing in an aqueous suspension: (a) a vinyl aromatic monomer; and (b) a vinyl phosphonate monoester in the presence of partially hydrolyzed polyacrylamide. Preferably, the vinyl phosphonate monoester has the structure: ##STR5## in which A and R separately represent monovalent radicals selected from the group consisting of hydrogen, C 1 -C 30 alkyl, aryl, and aralkyl. The vinyl phosphonate monoester is conveniently prepared by reacting the corresponding diester in aqueous media with at least one equivalent of aqueous base. Preferably, the base is an alkali metal or alkaline earth metal hydroxide, carbonate, bicarbonate, or the like. Acidification of the mixture, preferably with hydrochloric or phosphoric acid, generates the vinyl phosphonate monoester. This aqueous mixture can then be easily combined in any desired manner with a vinyl aromatic monomer, partially hydrolyzed polyacrylamide, and radical initiator to produce copolymers of the vinyl aromatic monomer and the vinyl phosphonate monoester. Alternatively, the vinyl phosphonate monoester can be isolated and purified following preparation from the diester. Usually, it will be more convenient to use the aqueous monoester "as is" for the copolymerization step. The copolymers of the invention--i.e., copolymers of vinyl aromatic monomers and vinyl phosphonic acids, monoesters, and diesters--are useful for making foamed articles. Thermoplastic expandable copolymer beads are first prepared by aqueous suspension polymerization according to one of the processes described above. The suspension polymerization processes differ depending upon the which type of vinyl phosphonic acid derivative is employed. The thermoplastic polymer beads may be impregnated with a foaming agent when polymerization is substantially complete. If desired, the foaming agent may be included with the charged reactants so that impregnation of the polymer occurs in situ during the polymerization. The foaming agents useful in this invention are any of those commonly known to those skilled in the art. Examples include hydrocarbons, such as butanes, pentane, and the like, fluorocarbons, air, carbon dioxide, and other pneumatogens. Any combination of foaming agents may be used. Generally, hydrocarbons are the most suitable foaming agents for in situ impregnations. It is often desirable to include a wax in the polymerization reaction. Suitable waxes include polyethylene waxes such as "Bareco-1000" wax (Product of Petrolite) and the like. Suitable waxes for use in the invention are soluble in styrene, but relatively insoluble in the polymer product. Useful waxes include, but are not limited to, low molecular weight linear hydrocarbons such as paraffins, natural waxes, Fischer-Tropsch waxes, and the like, and high molecular weight branched hydrocarbons such as high molecular weight polyisobutylene polymers and the like. Mixtures of waxes may be used. The impregnated beads are thermally expanded to form foamed beads, similar to polystyrene "prepuff." Typically, the expansion is performed by exposing the hard beads to steam. The methods suitable are well known to those skilled in the art. Suitable molding processes are also well known in the art. Pre-expanded or foamed beads are typically molded under steam pressure until the foamed beads fuse and expand to form a fused, foamed article. If desired, both a foaming agent and a wax may be included in the polymerization. For example, in one embodiment of the invention, styrene is copolymerized with 1-phenylvinyl phosphonic acid in the presence of pentane and "Bareco-1000" wax. After pre-expansion, the resilient foamed beads are steam molded to give a well-formed part. Molded articles made by the process of the invention show flame-retardant properties similar to commercial expanded polystyrene containing brominated flame-retardant additives, and can be formulated to pass burn tests such as the UL94HBF test. The following examples merely illustrate the invention. Those skilled in the art will recognize many possible variations that are within the spirit of the invention and scope of the claims. EXAMPLES 1-8 Suspension Copolymerization of Styrene and PVPA Effect of Suspending Agent A 350-mL pressure bottle was charged with 1-phenylvinyl phosphonic acid (PVPA) (8.5 g, 0.046 mol), styrene (91.5 g, 0.88 mol), deionized water (120 mL), benzoyl peroxide (0.6 g), tert-butyl perbenzoate (0.6 g), suspending agent (see Table 1), and optionally an alkali metal salt (Table 1). The bottle was placed in a temperature-controlled bottle polymerizer and continuously agitated while heating to 90° C over 1 hour. Heating at 90° C. was continued for 6 hours. The temperature was increased to 135° C. over 1 h and maintained at 135° C. for 2 h before cooling to 25° C over a one-hour period. The resulting polymer beads (if they formed) were filtered, washed with water and methanol, and then vacuum dried. As shown in Table 1, partially hydrolyzed polyacrylamide was the only suspending agent to give polymer beads. If the alkali metal salt was omitted, polymer beads formed (Comparative Example 6), but incorporation of the vinyl phosphonate monomer into the product was minimal. EXAMPLES 9-14 Suspension Copolymerization of Styrene and PVPA Effect of other Suspending Agents A 350-mL pressure bottle was charged with PVPA (10 g), styrene (90 g), deionized water (120 mL), benzoyl peroxide (0.6 g), tert-butylperbenzoate (0.6 g), potassium bromide (30 g), and suspending agent (see Table 2). The bottle was placed in a temperature-controlled bottle polymerizer. With continuous agitation, the bottle was heated to 90° C. over 1 hour, and maintained at 90° C. for 6 hours. Temperature was then increased to 135° C. over 1 hour, and kept at 135° C. for 2 hours before cooling to 25° C. over 1 hour. Only partially hydrolyzed polyacrylamide (PAM) was able to hold the suspension to give polymer beads. The results are summarized in Table 2. EXAMPLES 15-30 Suspension Copolymerization of Styrene and PVPA Effect of Amount and Identity of Salt on PVPA Incorporation and Bead Size Distribution The procedure of Examples 1-8 was generally followed. The amount of PVPA charged was 5 mole % based on the total amount of PVPA and styrene used. Partially hydrolyzed polyacrylamide was the only suspending agent used. Benzoyl peroxide was the initiator used for Examples 15-20. "VAZO-67" (2,2'-azobis(2-methylbutyronitrile) (a product of E.I. DuPont de Nemours and Company) was used for Examples 21 and 22. Examples 15-22 were heated only to 90° C. for 6 h, then cooled to 25° C. A combination of benzoyl peroxide and tert-butyl perbenzoate was used for Examples 23-30. The results appear in Table 3. As Comparative Example 15 illustrates, incorporation of PVPA into the copolymer is low in the absence of an alkali metal or alkaline earth metal salt. Small beads are possible with calcium and lithium salts (Examples 20 and 30), while large beads can be made with NaCl (Example 16), NaBr (Examples 24 and 25), and KBr (Examples 28 and 29). EXAMPLES 31-45 Suspension Copolymerization of Styrene and PVPA Effect of Tetraalkylammonium Compounds A 350-mL citrate polymerization bottle was charged with styrene (60 g), 1-phenylvinyl phosphonic acid, deionized water (68 g), benzoyl peroxide, tert-butyl perbenzoate, partially hydrolyzed polyacrylamide (0.13 g), tetraalkylammonium compound, and optional base (unstated reactant amounts shown in Table 4). The headspace was purged with nitrogen, and the bottle was capped. The bottle was placed in a temperature-controlled bottle polymerizer and continuously agitated by rocking. The bottle was heated at 90° C. for 12 hours. After cooling to 25° C., the bottle was opened, and the copolymer beads were isolated either by filtration or centrifugation. The beads were washed with deionized water, and then with methanol. The beads were then dried under vacuum (1 mm) at 80° C., and the amount of vinyl phosphonate monomer incorporated into the polymer was measured by determining phosphorus content. The results from a number of runs appear in Table 4. Comparative Example 31 shows that omission of the tetraalkylammonium compound results in incorporation of only a small percentage (<4 mole %) of the charged phosphonate monomer into the styrene/PVPA copolymer. Examples 32-38 illustrate the process of the invention using tetraalkylammonium halides with or without a base present. Examples 39-43 illustrate the process with tetraalkylammonium hydroxide compounds. Interestingly, 90% phosphonate monomer incorporation was achieved with 13 mole % phenylvinyl phosphonic acid charged. Comparative Examples 44 and 45 illustrate the criticality of using partially hydrolyzed polyacrylamide as the suspending agent. Beads were not obtained with either polyvinyl alcohol or tricalcium phosphate/polyvinyl alcohol. EXAMPLES 46-58 Suspension Copolymerization of Styrene with PVPA Diesters Effect of Initiator Type A 350-mL polymerization bottle was charged with styrene (104 g), 1-phenylvinyl phosphonic acid dimethyl ester (11 g), deionized water (120 g), initiator(s), and suspending agent(s) (see Table 5). The headspace was purged with nitrogen, and the bottle was capped. The bottle was placed in a temperature-controlled bottle polymerizer and continuously agitated by rocking. The bottle was heated at 90° C. for 6 hours, then at 130° C. for 6 hours. After cooling to 25° C., the bottle was opened, and the copolymer beads were separated from the suspension mixture by filtration or centrifugation. The beads were washed with water, then with methanol, and dried under vacuum (1 mm) at 80° C. The results of several runs with various suspending agents and initiator combinations appear in Table 5. As shown in Table 5, the choice of suspending agent is not especially critical when a diester of PVPA is used. When benzoyl peroxide was used as the only initiator, the suspension failed (Comparative Examples 52 and 53). EXAMPLES 59-62 Suspension Copolymerization of Styrene with PVPA Cyclic Diester A 350-mL citrate polymerization bottle was charged with styrene (60 g), 1-phenylvinyl-1-propylene glycol phosphonate (prepared as in Example 65), deionized water (70 g), benzoyl peroxide (0.20 g), t-butyl perbenzoate (0.15 g) and suspending agent(s) (Table 6). The headspace was purged with nitrogen, and the bottle was capped. The bottle was placed in a temperature-controlled bottle polymerizer and agitated by rocking. The bottle was heated at 90° C. for 6 h, then at 130° C. for 6 h. After cooling to 25° C., the bottle was opened, and the beads were isolated by filtration or centrifugation. The beads were washed with water, then with methanol, and were dried under vacuum (1 mm) at 80° C. Results from several runs appear in Table 6. The proton-decoupled 13 C NMR and 31 P spectra were consistent with a copolymer containing mostly acyclic (ring-opened) propylene glycol ester groups. COMPARATIVE EXAMPLES 63-64 Bulk Copolymerization of Styrene with PVPA Cyclic Diester A thick-walled glass tube equipped with a magnetic stir bar was evacuated, flushed with nitrogen, and charged with a premixed solution of styrene (20 g), 1-phenylvinyl-1-propylene glycol phosphonate (prepared as in Example 65), benzoyl peroxide, and t-butyl perbenzoate. The tube was closed and placed in an oil bath. The contents were stirred and heated at 90° C. for 6 h, and at 130° C. for 6 h. The tube was cooled to 30° C., and the copolymer was dissolved in tetrahydrofuran (100 mL). This solution was added to 1500 mL of methanol with stirring. The precipitated solids were washed with methanol and dried under vacuum (1 mm) at 80° C. The results from two runs appear in Table 6. The proton-decoupled 13 C NMR and 31 P spectra were consistent with a copolymer containing only cyclic (ring-intact) propylene glycol ester groups. EXAMPLE 65 Preparation of Cyclic Propylene Glycol Ester of 1-Phenylvinyl phosphonic acid A two-liter 3-neck flask equipped with magnetic stirring, addition funnel, thermometer, and inert gas inlet was charged with 1-phenylvinyl phosphonic acid (92 g) and dichloromethane (500 mL), and was cooled to 2° C. Propylene oxide (116 g) was added dropwise over 90 minutes from the addition funnel, during which time the temperature increased to 8° C. The mixture was allowed to warm to 23° C. while stirring for 16 h. Additional dichloromethane (500 mL) was added to the mixture. The organic phase was washed with deionized water (2×200 mL), was dried over magnesium sulfate, and was filtered. Solvent removal by rotary evaporation was followed by distillation at 0.5 mm. The fraction boiling between 160°-165° C. was collected and redistilled at 0.1 mm to give 66 g of 99%-pure 1-phenylvinyl-1-propylene glycol phosphonate. The compound displayed sharp 31 P NMR signals at 33.2 and 32.9 ppm. EXAMPLE 66 Preparation of 1-Phenyl-1-Monomethylphosphonate A 250-mL 3-neck flask equipped with a magnetic stir bar, thermometer, and nitrogen inlet was charged with 1-phenylvinyl-1-dimethylphosphonate (42 g) and deionized water (100 mL) containing dissolved sodium hydroxide (12 g). The reaction mixture was stirred until homogeneous (about 2 h). The reaction mixture was extracted with methyl t-butyl ether (MTBE) (2×100 mL). The aqueous layer was treated with 85% phosphoric acid (39 g) and then extracted with MTBE (4×100 mL). The combined MTBE layers were dried over magnesium sulfate, filtered, and stripped to give the monomethyl phosphonate (33 g, 82%) in adequate purity for polymerization. EXAMPLE 67 Suspension Copolymerization of Styrene and 1-Phenylvinyl-1-monomethylphosphonate A 350-mL citrate polymerization bottle was charged with styrene (60 g), 1-phenylvinyl-1-monomethylphosphonate (6 g as prepared in the preceding example), deionized water (70 g), benzoyl peroxide (0.20 g), t-butyl perbenzoate (0.15 g), and partially hydrolyzed polyacrylamide (0.13 g). The headspace was purged with nitrogen, and the bottle was capped. The bottle was placed in a temperature-controlled bottle polymerizer and agitated by rocking. The bottle was heated at 90° C. for 6 h, and at 130° C. for 6 h. After cooling to 25° C., the bottle was opened, and the copolymer beads were isolated by filtration or centrifugation. The beads were washed with deionized water, then with methanol, then dried under vacuum (1 mm) at 80° C. Yield: 61 g. EXAMPLE 68 Suspension Copolymerization of Styrene and 1-Phenylvinyl-1-monomethylphosphonate Prepared In-situ A 350-mL citrate polymerization bottle was charged with 1-phenylvinyl-1-dimethylphosphonate (6.5 g), sodium hydroxide (1.2 g), and deionized water (60 g). After stirring the reaction mixture for 2 h, 37% hydrochloric acid (3.0 g) was added. To this solution was added partially hydrolyzed polyacrylamide (130 mg) and a premixed solution of styrene (60 g), benzoyl peroxide (0.18 g), and t-butyl perbenzoate. The headspace was purged with nitrogen, and the bottle was capped. The bottle was placed in a temperature-controlled bottle polymerizer and was agitated by rocking. The bottle was heated to 90° C. for 6 h and at 130° C. for 6 h. After cooling to 25° C., the bottle was opened and the beads were isolated from the mixture by centrifugation. The beads were washed with deionized water, then with methanol, and dried under vacuum (1 mm) at 80° C. Yield: 62 g. The copolymer contained 1.2 weight percent phosphorus (indicating 88 % incorporation of vinylphosphonate monomer). EXAMPLE 69 Preparation of Foamed Articles from Styrene/PVPA Copolymers Post-polymerization Impregnation A 350-mL pressure bottle was charged with styrene (90 g), 1-phenylvinyl phosphonic acid (PVPA) (10 g), benzoyl peroxide (0.6 g), tert-butyl perbenzoate (0.5 g), deionized water (120 mL), potassium bromide (30 g), partially hydrolyzed polyacrylamide (0.8 g), and, optionally, "Bareco-1000" polyethylene wax (0, 0.2, or 0.4 g) (product of Petrolite). The bottle was agitated in a temperature-controlled polymerizer for 6 h at 90° C. The bottle was heated to 135° C. over 1 h, and kept at 135° C. for 2 h before cooling to 25° C. over 1 h. The resulting polymer beads were filtered, washed successively with water and methanol, and vacuum dried. The mole % PVPA found in the polymer was determined by phosphorus analysis to be 4.0-4.1% (about 67% incorporation of the charged phosphonate monomer). Copolymer beads prepared as described above were impregnated with pentane as follows. A pressure bottle was charged with polymer beads (55 g), tricalcium phosphate (1.65 g), 1% aqueous dodecylbenzene sulfonate solution ("Naccanol-90G, a product of Stephan Chemical) (0.55 mL), "Tween 20" surfactant (Product of ICI Americas) (0.06-0.6 g), and pentane (4.3-8.6 g). The bottle was agitated at 90° C. for 2 h, and then was heated to 110° C. over 1 h. Heating continued at 110° C. for 2 h before cooling to 25° C. over 6 h. Concentrated hydrochloric acid (10 mL) was added, and the beads were then filtered and washed with distilled water. After air drying for 4 h, the impregnated beads were expanded with steam. The density of the resulting prepuffed beads was within the range of about 1-10 pcf depending on conditions. High-density prepuff beads (greater than about 4 pcf density) were molded into good articles. EXAMPLE 70 Preparation of Low-Density Beads from Styrene/PVPA Copolymers In-situ Impregnation--No wax The procedure described above was followed with the following modifications: No wax was used. Pentane (7.5-10 g) was included with the initial reactants; thus impregnation was performed during the polymerization. The resulting impregnated beads were air dried for 4 h, then expanded with steam to give low-density (1.5 pcf) prepuffed beads. EXAMPLE 71 Preparation of a Foamed Article from Styrene/PVPA Copolymer In-situ Impregnation--Polyethylene Wax--KBr A 350-mL pressure bottle was charged with PVPA (10 g, 6 mole %), benzoyl peroxide (0.6 g), tert-butyl perbenzoate (0.5 g), styrene (90 g), deionized water (120 mL), potassium bromide (30 g), "Bareco-1000" polyethylene wax (0.2 g), partially hydrolyzed polyacrylamide (0.8 g), and pentane (10 g). The bottle was agitated at 90° C. for 6 h, and then was heated to 135° C. over 1 h. Heating continued at 135° C. for 2 h before cooling to 25° C. over 1 h. The resulting polymer beads were filtered and washed successively with water and methanol, then air dried for 4 h. The impregnated beads were then expanded with steam at 89° C. for 1 min. to give prepuff. The prepuffed beads were annealled for 16-20 h after steam expansion, then steam molded at 18 psi for 20 s to give a foamed article. (Beads that were expanded at 98° C. for 1-4 minutes gave low-density (<1 pcf) prepuff, but these were not satisfactory for molding.) EXAMPLES 72-74 Preparation of Foamed Articles from Styrene/PVPA Copolymers In-Situ Impregnation--Polyethylene Wax--Tetraalkylammonium salt A 350-mL pressure bottle was charged with PVPA (5.5 g, 5 mole %), benzoyl peroxide (0.18 g), tert-butyl perbenzoate (0.12 g), styrene (60 g), deionized water (68 mL), tetra-n-butylammonium bromide (2 g), partially hydrolyzed polyacrylamide (0.13 g), n-pentane (4.9 g), and "Bareco-1000" polyethylene wax (see Table 8). The bottle was agitated at 90° C. for 6 h, and then was heated to 135° C. over 1 h. Heating continued at 135° C. for 2 h before cooling to 25° C. over 1 h. The resulting polymer beads were filtered and washed successively with water and methanol, then air dried for 4 h. The impregnated beads were then expanded with steam under the conditions specified in Table 7 to give prepuff. The prepuffed beads were annealled for 16-20 h after steam expansion. Some of the prepuffed beads were steam molded at 20 psi for 15 seconds into foamed articles (Table 7). EXAMPLE 75 Pentane Impregnation of Poly(styrene-co-1-phenylvinyl-1-dimethylphosphonate), Expansion, and Molding of the same A 350-mL citrate polymerization bottle was charged with 50 g of 14-30 mesh beads of poly(styrene-co-1-phenylvinyl-1-dimethylphosphonate) (prepared as in Example 55), deionized water (50 g), tricalcium phosphate (1.5 g), dodecylbenzene sulfonate (0.5 mL of 1% aqueous solution), "Tween-80" surfactant (Product of ICI Americas) (0.05 g), and pentane (3.9 g). The bottle was capped, placed in a rocker reactor, and with constant agitation, was heated from 25° C. to 90° C. over 1 h, held at 90° C. for 2 h, heated from 90° C. to 120° C. over 1 h, held at 120° C. for 2 h, and cooled to 25° C. over 6 h. The bottle was opened, and 12N HCl (25 mL) was added with shaking. The beads were isolated by centrifugation and rinsed with deionized water. The beads were dried by centrifugation, and air dried 3 h. After air drying, a portion of the beads was analyzed for volatile content by weighing, heating in an oven at 150° C. for 1 h, and reweighing. Volatile content of the beads was about 6%. Beads as prepared above were expanded by steaming at 100° C. for 30 s. The expanded beads were allowed to cure overnight. The dried beads had a density of about 1 pcf. The cured beads were molded into foam parts by vacuuming the expanded beads into a preheated (130° C.) mold of the desired shape. Foam parts of poly(styrene-co-1-phenylvinyl-1-dimethylphosphonate) containing 5 mole percent of the phosphonate diester recurring units (1.3 weight percent phosphorus content) passed the UL94HBF test. EXAMPLE 76 Preparation, In-situ Impregnation, Expansion, and Molding of Poly(styrene-co-1-phenylvinyl-1-propylene glycol phosphonic acid) A 350-mL citrate polymerization bottle was charged with styrene (60 g, 0.58 mol), 1-phenylvinyl-1-propylene glycol phosphonate (prepared as in Example 65) (7.0 g, 0.31 mol), deionized water (70 g), benzoyl peroxide (0.20 g), tert-butyl perbenzoate (0.12 g), partially hydrolyzed polyacrylamide (0.27 g), "Bareco-1000" wax (0.20 g), and pentane (3.5 g). The headspace was purged with nitrogen, and the bottle was capped. The bottle was placed in a temperature-controlled bottle polymerizer, and was agitated by rocking. The bottle was heated at 90° C. for 6 h, and at 130° C. for 6 h. After cooling to 25° C., the bottle was opened and the beads were isolated by filtration. The beads were allowed to air dry for 16 h, and were then expanded with steam at 98° C. for 90 s to give prepuff beads with a density of 1.4 pcf. After a 16-h annealling period, the prepuff was molded into a well-fused part. TABLE 1______________________________________Suspension Copolymerization of Styrene and PVPAEffect of Suspending AgentSuspending Agent PolymerEx TCP (g) PVA (g) PAM (g) Salt Wt %* beads?______________________________________C1 0.75 2.25 0 -- 0 NoC2 0.75 0 0 NaCl 20 NoC3 0.75 2.25 0 NaCl 20 NoC4 0.75 2.25 0 NaBr 20 NoC5 0.75 5.0 0 KBr 25 NoC6 0 0 0.4 -- 0 Yes.sup. 70 0 0.4 NaCl 20 Yes.sup. 80 0 0.4 KBr 25 Yes______________________________________ TCP = tricalcium phosphate; PVA = polyvinyl alcohol (1 wt. % aqueous solution); PAM = partially hydrolyzed polyacrylamide. Benzoyl peroxide (0.6 g) and tertbutyl perbenzoate (0.6 g) were used as initiators for each run. *Weight percent of salt used based on the amount of water present. TABLE 2______________________________________Suspension Copolymerization of Styrene and PVPAEffect of Other Suspending AgentsEx Suspending agent Amount (g) Suspension results______________________________________ 9 PAM 0.4 BeadsC10 HyEtCell/PVA 0.6/0.6 FailedC11 Xanthan Gum 0.12 FailedC12 PAA 1.2 FailedC13 TAMOL/HyEtCell 1.2/0.6 FailedC14 barium sulfate 0.92 Failed______________________________________ PAM = Partially hydrolyzed polyacrylamide; HyEtCell = hydroxyethyl cellulose; PAA = sodium salt of polyacrylic acid (MW = 6000); TAMOL (A product of Rohm and Haas Company) = sodium salt of condensed naphthalenesulfonic acid TABLE 3__________________________________________________________________________Suspension Copolymerization of Styrene and PVPAusing Partially Hydrolyzed PolyacrylamideEffect of Salt on Vinyl Phosphonic Acid MonomerIncorporation and on Bead-Size Distribution Bead Size Distribution (%)Ex Salt Wt % Initiator Mole % PVA <16 m 16-45 m >45 m__________________________________________________________________________C15.sup. -- 0 A 0.4 0 90 1016 NaCl 10 A 3.5 69 29 217 NaCl 20 A 4.5 35 61 418 NaCl 25 A -- suspension failed19 CaCl.sub.2 10 A 2.0 36 62 220 CaCl.sub.2 20 A 4.9 0.4 43 5621 NaCl 10 B 3.8 56 43 122 NaCl 20 B -- suspension failed23 NaCl 20 C 4.5 0 81 1924 NaBr 20 C 3.1 87 12 125 NaBr 25 C 3.8 88 11 0.426 NaBr 30 C 3.8 44 55 127 KBr 20 C 2.4 23 73 428 KBr 25 C 3.6 95 5 029 KBr 30 C 4.2 98 2 030 LiCl 20 C 4.2 4 44 52__________________________________________________________________________ Initiators: A-benzoyl peroxide (0.6 g); B-VAZO-67 (0.6 g); C-benzoyl peroxide (0.6 g) and tertbutyl perbenzoate (0.6 g). Mole % PVPA is the mole percent of 1phenylvinyl phosphonic acid incorporated into the polymer calculated from P elemental analysis (5 mol % = quantitative). Bead sizes are mesh values-distributions are in weight percent. TABLE 4__________________________________________________________________________Suspension Copolymerization of Styrene and PVPAEffect of Tetraalkylammonium Compounds Mol % Mol %Ex PVPA Suspend R.sub.4 N+ Base PVPA in % PVPA Beads# charged Agent Cpd. Eq. Cpd. Eq. copolymer incorp. form?__________________________________________________________________________C31.sup. 5 PAM -- -- -- -- 0.17 3.4 Yes32 5 PAM TBAB 0.30 -- -- 3.8 76 Yes33 5 PAM TBAB 0.20 NaOH 0.22 3.5 70 Yes34 5 PAM THXAC 0.20 -- -- 4.2 84 Yes35 5 PAM TPNAB 0.28 -- -- 4.2 84 Yes36 5 PAM TPNAB 0.28 NaOH 0.22 3.8 76 Yes37 5 PAM TPNAB 0.28 Na.sub.2 CO.sub.3 0.22 3.8 76 Yes38 5 PAM TPNAB 0.28 NaHCO.sub.3 0.20 4.2 84 Yes39 5 PAM TBAH 0.10 -- -- 3.1 62 Yes40 5 PAM TBAH 0.20 -- -- 3.5 70 Yes41 7 PAM TBAH 0.20 -- -- 4.9 70 Yes42 13 PAM TBAH 0.21 -- -- 11.7 90 Yes43 5 PAM BTMAH 0.05 -- -- 1.4 28 YesC44.sup. 5 PVA TBAH 0.20 -- -- -- -- NoC45.sup. 5 PVA/TCP TBAH 0.20 -- -- -- -- No__________________________________________________________________________ Mol % PVPA charged = mole percent of 1phenylvinyl phosphonic acid charged relative to total monomer. Initiator = benzoyl peroxide(BPO)/tbutyl perbenzoate(TPB) (0.3/0.2 wt % based on styrene) in each example except Ex 41 (BPO/TPB = 0.5/0.3 wt %) and Ex 43 (BPO = 0.3 wt %). Suspending agents: PAM = partially hydrolyzed polyacrylamide; PVA = polyvinyl alcohol; TCP = tricalcium phosphate. Tetraalkylammonium compounds: TBAB = tetran-butylammonium bromide; THXAC tetran-hexylammonium chloride; TPNAB = tetran-pentylammonium bromide; TBA = tetran-butylammonium hydroxide; BTMAH = benzyltrimethylammonium hydroxide. Mol % PVPA in copolymer calculated from phosphorus elemental analysis. % PVPA incorp = percentage of charged 1phenylvinyl phophonic acid that wa incorporated into the copolymer. TABLE 5__________________________________________________________________________Suspension Copolymerization of Styrene and PVPA DiestersEffect of Suspending Agent and Initiator Mole % Mole %Suspend Agent (wt %) Initiator (wt %) dimethyl ester dimethyl esterEx PAM TCP PVA BPO TPB charged in Copolymer__________________________________________________________________________46 0 2.5 7.5 0.2 0.1 1.0 0.9547 0.2 0 0 0.2 0.1 1.0 0.7848 0 0.8 2.4 0.3 0.15 2.0 1.649 0.4 0 0 0.3 0.15 2.0 1.950 0.4 0 0 0.3 0.15 3.0 2.251 0.4 0 0 0.3 0.15 4.0 3.2C52.sup. 0.4 0 0 0.3 0 5.0 No BeadsC53.sup. 0 0.7 0 0.3 0 5.0 No Beads54 0.4 0 0 0.3 0.15 5.0 4.255 0 0.7 2.3 0.3 0.15 5.0 4.656 0.4 0 0 0.3 0.15 9.0 10.457 0 0.7 2.3 Note A 5.0 4.258 0.2 0 0 Note B 5.0 4.2__________________________________________________________________________ PAM = partially hydrolyzed polyacrylamide; TCP = tricalcium phosphate; PVA = polyvinylalcohol (1 wt. % aqueous solution); BPO = benzoyl peroxide TPB = tertbutyl perbenzoate. Note A: "Lupersol 256" initiator (product of Pennwalt) (0.55 g) was used; reaction at 90° C. for 5 h, then at 120° C. for 5 h. Note B: "VAZO 88" initiator (product of DuPont) (0.25 g) and TPS (0.14 g) were used as the initiators. Mole % dimethyl ester in copolymer calculated from phosphorus elemental analysis. TABLE 6__________________________________________________________________________Copolymerization of Styrene and Cyclic Vinylphosphonate EsterEx Polym. Init Wt % Suspend Wt % Mole % PVPGP Mole % PVPGP Beads# type BPO/TPB PAM/TCP/PVA charged in Copolymer form?__________________________________________________________________________59 Suspen. 0.3/0.2 0.4/0/0 1 0.51 Yes60 Suspen. 0.3/0.2 0.4/0/0 5 3.9 Yes61 Suspen. 0.3/0.2 0.4/0/0 10 10.6 YesC62.sup. Suspen. 0.3/0.2 0/0.8/2.3 5 -- NoC63.sup. Bulk 0.3/0.2 -- 5 5.0 --C64.sup. Bulk 0.3/0.2 -- 10 10.6 --__________________________________________________________________________ BPO = benzoyl peroxide; TPB = tertbutyl perbenzoate PAM = partially hydrolyzed polyacrylamide; TCP = tricalcium phosphate; PVA = polyvinyl alcohol (1 wt. % aqueous solution). Mole % PVPGP charged mole % of 1phenylvinyl-1-propylene glycol phosphonate charged relative to total monomer. Mole % PVPGP in copolymer is the calculated amount from phosphorus elemental analysis. TABLE 7______________________________________PVPA/Styrene Copolymers made w/ In-situ ImpregnationWax--Bu.sub.4 NBr (Examples 72-74)Prepuff densities and molding results PrepuffWax.sup.1 Prepuff conditions density SampleEx # (wt %) Temp (°C.) Time (min) (pcf) molded?.sup.2______________________________________72 a 0.10 98 1.0 1.1 No b 92 1.0 2.0 No c 90 1.0 2.0 No73 a 0.20 98 1.0 1.2 No b 95 1.0 1.1 Yes c 92 1.0 1.4 Yes d 90 1.0 1.7 Yes74 a 0.40 98 1.0 1.1 No b 92 1.0 2.1 No______________________________________ .sup.1 Weight % of "BARECO1000" wax based on total monomer. .sup.2 Lowdensity beads that were preexpanded at 90-95° C. were molded into wellformed articles; molding of higher density beads and bead preexpanded at 98° C. was not attempted.

A process for making thermoplastic copolymer beads from vinyl aromatic monomers and vinyl phosphonic acid derivatives is disclosed. A process for making foamed articles from the beads is also disclosed. The foamed articles are useful for packaging and construction applications.

RELATED APPLICATIONS [0001] This application is a continuation-in-part of copending and commonly assigned U.S. patent application Ser. No. 11/200,952 entitled “Process For The Production Of Nano-Scale Metal Particles,” filed on Aug. 10, 2005 in the name of Robert A. Mercuri, and copending and commonly assigned U.S. patent application Ser. No. 11/201,368 entitled “Production of Nano-Scale Metal Particles,” filed on Aug. 10, 2005 in the name of Robert A. Mercuri, the disclosures of each of which are incorporated by reference herein. TECHNICAL FIELD [0002] The present invention relates to a process for the production of chain agglomerations of nano-scale metal particles, useful for catalysis and other applications. By the practice of the present invention, chain agglomerations of nano-scale metal particles can be produced, and collected with precision and flexibility. Thus, the invention provides a practical and cost-effective system for preparing chain agglomerations of nano-scale metal particles. BACKGROUND OF THE INVENTION [0003] Catalysts are becoming ubiquitous in modern chemical processing. Catalysts are used in the production of materials such as fuels, lubricants, refrigerants, polymers, drugs, etc., as well as playing a role in water and air pollution mediation processes. Indeed, catalysts have been ascribed as having a role in fully one third of the material gross national product of the United States, as discussed by Alexis T. Bell in “The Impact of Nanoscience on Heterogeneous Catalysis” (Science, Vol. 299, pg. 1688, 14 Mar. 2003). [0004] Generally speaking, catalysts can be described as small particles deposited on high surface area solids. Traditionally, catalyst particles can range from the sub-micron up to tens of microns. One example described by Bell is the catalytic converter of automobiles, which consist of a honeycomb whose walls are coated with a thin coating of porous aluminum oxide (alumina). In the production of the internal components of catalytic converters, an aluminum oxide wash coat is impregnated with nanoparticles of a platinum group metal catalyst material. In fact, most industrial catalysts used today include platinum group metals especially platinum, rhodium and iridium or alkaline metals like cesium, at times in combination with other metals such as iron or nickel. [0005] The size of these particles has been recognized as extremely significant in their catalytic function. Indeed it is also noted by Bell that the performance of a catalyst can be greatly affected by the particle size of the catalyst particles, since properties such as surface structure and the electronic properties of the particles can change as the size of the catalyst particles changes. [0006] In his study on nanotechnology of catalysis presented at the Frontiers in Nanotechnology Conference on May 13, 2003, Eric M. Stuve of the Department of Chemical Engineering of the University of Washington, described how the general belief is that the advantage of use of nano-sized particles in catalysis is due to the fact that the available surface area of small particles is greater than that of larger particles, thus increasing effectiveness by providing more metal atoms at the surface to optimize catalysis using such nano-sized catalyst materials. However, Stuve points out that the advantages of the use of nano-sized catalyst particles may be more than simply due to the size effect. Rather, the use of nanoparticles can exhibit modified electronic structure and a different shape with actual facets being present in the nanoparticles, which provide for interactions which can facilitate catalysis. Indeed, Cynthia Friend, in “Catalysis On Surfaces” (Scientific American, April 1993, p. 74), posits catalyst shape, and, more specifically, the orientation of atoms on the surface of the catalyst particles, as important in catalysis. In addition, differing mass transport resistances may also improve catalyst function. Thus, the production of nano-sized metal particles for use as catalysts on a more flexible and commercially efficacious platform is being sought. Moreover, other applications for nano-scale particles are being sought, whether for the platinum group metals traditionally used for catalysis or other metal particles. [0007] Conventionally, however, catalysts are prepared in two ways. One such process involves catalyst materials being deposited on the surface of carrier particles such as carbon blacks or other like materials, with the catalyst-loaded particles then themselves being loaded on the surface at which catalysis is desired. One example of this is in the fuel cell arena, where carbon black or other like particles loaded with platinum group metal catalysts are then themselves loaded at the membrane/electrode interface to catalyze the breakdown of molecular hydrogen into atomic hydrogen to utilize its component protons and electrons, with the resulting electrons passed through a circuit as the current generated by the fuel cell. One major drawback to the preparation of catalyst materials through loading on a carrier particle is in the amount of time the loading reactions take, which can be measured in hours in some cases. [0008] To wit, in U.S. Pat. No. 6,716,525, Yadav and Pfaffenbach describe the dispersing of nano-scale powders on coarser carrier powders in order to provide catalyst materials. The carrier particles of Yadav and Pfaffenbach include oxides, carbides, nitrides, borides, chalcogenides, metals and alloys. The nanoparticles dispersed on the carriers can be any of many different materials according to Yadav and Pfaffenbach, including precious metals such as platinum group metals, rare earth metals, the so-called semi-metals, as well as non-metallic materials, and even clusters such as fullerenes, alloys and nanotubes. [0009] Alternatively, the second common method for preparing catalyst materials involves directly loading catalyst metals such as platinum group metals on a support without the use of carrier particles which can interfere with the catalytic reaction. For example, many automotive catalytic converters, as discussed above, have catalyst particles directly loaded on the aluminum oxide honeycomb which forms the converter structure. The processes needed for direct deposition of catalytic metals on support structures, however, are generally operated at extremes of temperature and/or pressures. For instance one such process is chemical sputtering at temperatures in excess of 1,500° C. and under conditions of high vacuum. Thus, these processes are difficult and expensive to operate. [0010] In an attempt to provide nano-scale catalyst particles, Bert and Bianchini, in International Patent Application Publication No. WO 2004/036674, suggest a process using a templating resin to produce nano-scale particles for fuel cell applications. Even if technically feasible, however, the Bert and Bianchini methods require high temperatures (on the order of 300° C. to 800° C.), and require several hours. Accordingly, these processes are of limited value. [0011] Taking a different approach, Sumit Bhaduri, in “Catalysis With Platinum Carbonyl Clusters,” Current Science, Vol. 78, No. 11, 10 Jun. 2000, asserts that platinum carbonyl clusters, by which is meant polynuclear metal carbonyl complexes with three or more metal atoms, have potential as redox catalysts, although the Bhaduri publication acknowledges that the behavior of such carbonyl clusters as redox catalysts is not understood in a comprehensive manner. Indeed, metal carbonyls have been recognized for use in catalysis in other applications. [0012] Metal carbonyls have also been used as, for instance, anti-knock compounds in unleaded gasolines. However, more significant uses of metal carbonyls are in the production and/or deposition of the metals present in the carbonyl, since metal carbonyls are generally viewed as easily decomposed and volatile resulting in deposition of the metal and carbon monoxide. [0013] Generally speaking, carbonyls are transition metals combined with carbon monoxide and have the general formula M x (CO) y , where M is a metal in the zero oxidation state and where x and y are both integers. While many consider metal carbonyls to be coordination compounds, the nature of the metal to carbon bond leads some to classify them as organometallic compounds. In any event, the metal carbonyls have been used to prepare high purity metals, although not for the production of nano-scale metal particles. As noted, metal carbonyls have also been found useful for their catalytic properties such as for the synthesis of organic chemicals in gasoline antiknock formulations. [0014] Accordingly, what is needed is a system and process for the production of nano-scale metal particles for use as, e.g., catalyst materials. The desired system can be used for the preparation of nano-scale particles loaded on a carrier particle but, significantly, can also be used for the deposit or collection of nano-scale particles directly on a surface without the requirement for extremes in temperature and/or pressures. SUMMARY OF THE INVENTION [0015] A system and process for the production of chain agglomerations of nano-scale metal particles is presented. By nano-scale particles is meant particles having an average diameter of no greater than about 1,000 nanometers (nm), e.g., no greater than about one micron. More preferably, the particles produced by the inventive system have an average diameter no greater than about 250 nm, most preferably no greater than about 20 nm. [0016] Preferably, the particles produced by the invention are roughly spherical or isotropic, meaning they have an aspect ratio of about 1.4 or less, although particles having a higher aspect ratio can also be prepared and used as catalyst materials. The aspect ratio of a particle refers to the ratio of the largest dimension of the particle to the smallest dimension of the particle (thus, a perfect sphere has an aspect ratio of 1.0). The diameter of a particle for the purposes of this invention is taken to be the average of all of the diameters of the particle, even in those cases where the aspect ratio of the particle is greater than 1.4. [0017] Chain agglomerations of nano-scale metal particles can be produced by the present invention, which comprise hundreds, or even thousands, of nano-scale metal particles organized in an elongate arrangement (as opposed to a spherical or cluster arrangement), and can appear to the naked eye as fibrous in nature. More particularly, each chain agglomeration of nano-scale metal particles has an aspect ratio, that is, ratio of major dimension (i.e., length) to minor dimension (i.e., width or diameter) of at least about 700:1, more advantageously at least about 900:1. As such, the surface area of the inventive nano-scale metal particle chain agglomerations makes the agglomerations uniquely effective in applications such as catalysis. [0018] In the practice of the present invention, a decomposable metal-containing moiety is fed into a reactor vessel and sufficient energy to decompose the moiety applied, such that the moiety decomposes and nano-scale metal particles are deposited on a support or in a collector. The decomposable moiety used in the invention can be any decomposable metal-containing material, including an organometallic compound, a metal complex or a metal coordination compound, provided that the moiety can be decomposed to provide free metals under the conditions existing in the reactor vessel, such that the free metal can be deposited on a support or collected by a collector. One example of a suitable moiety for use in the invention is a metal carbonyl, such as nickel or iron carbonyls, or noble metal carbonyls. [0019] The invention is advantageously practiced in an apparatus comprising a reactor vessel, at least one feeder for feeding or supplying the decomposable moiety into the reactor vessel, a support or collector which is operatively connected to the reactor vessel for deposit or collection of nano-scale metal particles produced on decomposition of the decomposable moiety, and a source of energy capable of decomposing the decomposable moiety. The source of energy should act on the decomposable moiety such that the moiety decomposes to provide nano-scale metal particles which are deposited on the support or collected by the collector. [0020] The reactor vessel can be formed of any material which can withstand the conditions under which the decomposition of the moiety occurs. Generally, where the reactor vessel is a closed system, that is, where it is not an open ended vessel permitting reactants to flow into and out of the vessel, the vessel can be under subatmospheric pressure, by which is meant pressures as low as about 250 millimeters (mm). Indeed, the use of subatmospheric pressures, as low as about 1 mm of pressure, can accelerate decomposition of the decomposable moiety and provide smaller nano-scale particles. However, one advantage of the invention is the ability to produce nano-scale particles at generally atmospheric pressure, i.e., about 760 mm. Alternatively, there may be advantage in cycling the pressure, such as from sub-atmospheric to generally atmospheric or above, to encourage nano-deposits within the structure of the particles or supports. Of course, even in a so-called “closed system,” there needs to be a valve or like system for relieving pressure build-up caused, for instance, by the generation of carbon monoxide (CO) or other by-products. Accordingly, the use of the expression “closed system” is meant to distinguish the system from a flow-through type of system as discussed hereinbelow. [0021] When the reactor vessel is a “flow-through” reactor vessel, that is, a conduit through which the reactants flow while reacting, the flow of the reactants can be facilitated by drawing a partial vacuum on the conduit, although no lower than about 250 mm is necessary in order to draw the reactants through the conduit towards the vacuum apparatus, or a flow of an inert gas such as nitrogen or argon can be pumped through the conduit to thus carry the reactants along the flow of the inert gas. [0022] Indeed, the flow-through reactor vessel can be a fluidized bed reactor, where the reactants are borne through the reactor on a stream of a fluid. This type of reactor vessel may be especially useful where the nano-scale metal particles produced are intended to be loaded on support materials, like carbon blacks or the like, or where the metal particles are to be loaded on an ion exchange or similar resinous material. [0023] The at least one feeder supplying the decomposable moiety into the reactor vessel can be any feeder sufficient for the purpose, such as an injector which carries the decomposable moiety along with a jet of a gas such as an inert gas like argon or nitrogen, to thereby carry the decomposable moiety along the jet of gas through the injector nozzle and into the reactor vessel. The gas employed can be a reactant, like oxygen or ozone, rather than an inert gas. This type of feeder can be used whether the reactor vessel is a closed system or a flow-through reactor. [0024] Supports useful in the practice of the invention can be any material on which the nano-scale metal particles produced from decomposition of the decomposable moieties can be deposited. In a preferred embodiment, the support is the material on which the catalyst metal is ultimately destined, such as the aluminum oxide honeycomb of a catalytic converter in order to deposit nano-scale particles on catalytic converter components without the need for extremes of temperature and pressure required by sputtering and like techniques. Alternatively, a collector capable of collecting nano-scale metal particles, such as a cyclonic or centrifugal collector, is employed. [0025] The support or collector can be disposed within the reactor vessel (indeed this is required in a closed system and is practical in a flow-through reactor). However, in a flow-through reactor vessel, the flow of reactants can be directed at a support positioned outside the vessel, at its terminus, especially where the flow through the flow-through reactor vessel is created by a flow of an inert gas. Alternatively, in a flow-through reactor, the flow of nano-scale metal particles produced by decomposition of the decomposable moiety can be directed into a centrifugal or cyclonic collector which collects the nano-scale particles in a suitable container for future use. [0026] The energy employed to decompose the decomposable moiety can be any form of energy capable of accomplishing this function. For instance, electromagnetic energy such as infrared, visible, or ultraviolet light of the appropriate wavelengths can be employed. Additionally, microwave and/or radio wave energy, or other forms of sonic energy can also be employed (example, a spark to initiate “explosive” decomposition assuming suitable moiety and pressure), provided the decomposable moiety is decomposed by the energy employed. Thus, microwave energy, at a frequency of about 2.4 gigahertz (GHz) or induction energy, at a frequency which can range from as low as about 180 hertz (Hz) up to as high as about 13 mega Hz can be employed. A skilled artisan would readily be able to determine the form of energy useful for decomposing the different types of decomposable moieties which can be employed. [0027] One preferred form of energy which can be employed to decompose the decomposable moiety is heat energy supplied by, e.g., heat lamps, radiant heat sources, or the like. Such heat can be especially useful for highly volatile moieties, such as metal carbonyls in transparent vessels. In such case, the temperatures needed are no greater than about 500° C., and generally no greater than about 250° C. Indeed, generally, temperatures no greater than about 200° C. are needed to decompose the decomposable moiety and produce nano-scale metal particles therefrom. [0028] Depending on the source of energy employed, the reactor vessel should be designed so as to not cause deposit of the nano-scale metal particles on the vessel itself (as opposed to the collector) as a result of the application of the source of energy. In other words, if the source of energy employed is heat, and the reactor vessel itself becomes heated to a temperature at or somewhat higher than the decomposition temperature of the decomposable moiety during the process of applying heat to the decomposable moiety to effect decomposition, then the decomposable moiety will decompose at the walls of the reactor vessel, thus coating the reactor vessel walls with nano-scale metal particles rather than collecting the nano-scale metal particles with the collector (one exception to this general rule occurs if the walls of the vessel are so hot that the decomposable moiety decomposes within the reactor vessel and not on the vessel walls, as discussed in more detail below). [0029] One way to avoid this is to direct the energy directly at the collector. For instance, if heat is the energy applied for decomposition of the decomposable moiety, the support or collector can be equipped with a source of heat itself, such as a resistance heater in or at a surface of the support or collector such that the support or collector is at the temperature needed for decomposition of the decomposable moiety and the reactor vessel itself is not. Thus, decomposition occurs at the support or collector and formation of nano-scale particles occurs principally at the support or collector. When the source of energy employed is other than heat, the source of energy can be chosen such that the energy couples with the support or collector, such as when microwave or induction energy is employed. In this instance, the reactor vessel should be formed of a material which is relatively transparent to the source of energy, especially as compared to the support or collector. [0030] For the production of the inventive chain agglomerations, the source of heat is advantageously a resistance heater, such as a wire, disposed within the flow of decomposable moieties. The heated wire provides a point of contact for the decomposition of decomposable moieties to form nano-scale metal particles; additional decomposition then occurs on the previously formed particles, and continues as chains of nano-scale metal particles are formed from these initial particles produced on the wire. While the precise mechanism for this phenomenon is not fully understood, it is believed that decomposition of decomposable moieties to produce nano-scale metal particles occurs by conduction along the chain as it forms. In other words, nano-scale metal particles are formed on the wire, which then cause further decomposition of decomposable moieties thereon by heat conduction along the metal particles formed on the wire, and so on. [0031] Especially in situations when the support or collector is disposed outside the reactor vessel when a flow-through reactor vessel is employed with a support or collector at its terminus (whether a solid substrate collector for depositing of nano-scale metal particles thereon or a cyclonic or like collector for collecting the nano-scale metal particles for a suitable container), the decomposition of the decomposable moiety occurs as the moiety is flowing through the flow-through reactor vessel and the reactor vessel should be transparent to the energy employed to decompose the decomposable moiety. Alternatively, whether or not the support or collector is inside the reactor vessel, or outside it, the reactor vessel can be maintained at a temperature below the temperature of decomposition of the decomposable moiety, where heat is the energy employed. One way in which the reactor vessel can be maintained below the decomposition temperatures of the moiety is through the use of a cooling medium like cooling coils or a cooling jacket. A cooling medium can maintain the walls of the reactor vessel below the decomposition temperatures of the decomposable moiety, yet permit heat to pass within the reactor vessel to heat the decomposable moiety and cause decomposition of the moiety and production of nano-scale metal particles. [0032] In an alternative embodiment which is especially applicable where both the walls of the reactor vessel and the gases in the reactor vessel are generally equally susceptible to the heat energy applied (such as when both are relatively transparent), heating the walls of the reactor vessel, when the reactor vessel is a flow-through reactor vessel, to a temperature substantially higher than the decomposition temperature of the decomposable moiety can permit the reactor vessel walls to themselves act as the source of heat. In other words, the heat radiating from the reactor walls will heat the inner spaces of the reactor vessel to temperatures at least as high as the decomposition temperature of the decomposable moiety. Thus, the moiety decomposes before impacting the vessel walls, forming nano-scale particles which are then carried along with the gas flow within the reactor vessel, especially where the gas velocity is enhanced by a vacuum. This method of generating decomposition heat within the reactor vessel is also useful where the nano-scale particles formed from decomposition of the decomposable moiety are being attached to carrier materials (like carbon black) also being carried along with the flow within the reactor vessel. In order to heat the walls of the reactor vessel to a temperature sufficient to generate decomposition temperatures for the decomposable moiety within the reactor vessel, the walls of the reactor vessel are preferably heated to a temperature which is significantly higher than the temperature desired for decomposition of the decomposable moiety(ies) being fed into the reactor vessel, which can be the decomposition temperature of the decomposable moiety having the highest decomposition temperature of those being fed into the reactor vessel, or a temperature selected to achieve a desired decomposition rate for the moieties present. For instance, if the decomposable moiety having the highest decomposition temperature of those being fed into the reactor vessel is nickel carbonyl, having a decomposition temperature of about 50° C., then the walls of the reactor vessel should preferably be heated to a temperature such that the moiety would be heated to its decomposition temperature several (at least three) millimeters from the walls of the reactor vessel. The specific temperature is selected based on internal pressure, composition and type of moiety, but generally is not greater than about 250° C. and is typically less than about 200° C. to ensure that the internal spaces of the reactor vessel are heated to at least 50° C. [0033] In any event, the reactor vessel, as well as the feeders, can be formed of any material which meets the requirements of temperature and pressure discussed above. Such materials include a metal, graphite, high density plastics or the like. Most preferably the reactor vessel and related components are formed of a transparent material, such as quartz or other forms of glass, including high temperature glass commercially available as Pyrex® materials. [0034] Thus, in the process of the present invention, decomposable metal-containing moieties are fed into a reactor vessel where they are exposed to a source of energy sufficient to decompose the moieties and produce nano-scale metal particles, especially chain agglomerations of nano-scale metal particles. The decomposable moieties are fed into a closed-system reactor under vacuum or in the presence of an inert gas; similarly, the moieties are fed into a flow-through reactor where the flow is created by drawing a vacuum or flowing an inert gas through the flow-through reactor. The energy applied is sufficient to decompose the decomposable moiety in the reactor or as it as flowing through the reactor, and free the metal from the moiety and thus create nano-scale metal particles which are deposited on a support or collected in a collector. Where heat is the energy used to decompose the decomposable moiety, temperatures no greater than about 500° C., more preferably no greater than about 250° C., and most preferably no greater than about 200° C., are required to produce nano-scale metal particles, which can then be directly deposited on the substrate for which they are ultimately intended without the use of carrier particles and in a process requiring only minutes and not under extreme conditions of temperature and pressure. Indeed, the process of the present invention often requires less than about one minute to produce nano-scale particles and, in some embodiments, can require less than about 5 seconds. [0035] In one embodiment of the inventive process, a single feeder feeds a single decomposable moiety into the reactor vessel for formation of nano-scale metal particles. In another embodiment, however, a plurality of feeders each feeds decomposable moieties into the reactor vessel. In this way, all feeders can feed the same decomposable moiety or different feeders can feed different decomposable moieties, such as additional metal carbonyls, so as to provide nano-scale particles containing different metals such as platinum-nickel combinations or nickel-iron combinations as desired, in proportions determined by the amount of the decomposable moiety fed into the reactor vessel. For instance, by feeding different decomposable moieties through different feeders, one can produce a nano-scale particle having a core of a first metal, with domains of a second or third, etc. metal coated thereon. Indeed, altering the decomposable moiety fed into the reactor vessel by each feeder can alter the nature and/or constitution of the nano-scale particles produced. In other words, if different proportions of metals making up the nano-scale particles, or different orientations of the metals making up the nano-scale particles is desired, altering the decomposable moiety fed into the reactor vessel by each feeder can produce such different proportions or different orientations. [0036] Indeed, in the case of the flow-through reactor vessel, each of the feeders can be arrayed about the circumference of the conduit forming the reactor vessel at approximately the same location, or the feeders can be arrayed along the length of the conduit so as to feed decomposable moieties into the reactor vessel at different locations along the flow path of the conduit to provide further control of the nano-scale particles produced. [0037] While it is anticipated that the inventive process and apparatus may also produce particles that are larger than nano-scale in size along with the nano-scale particles desired, the larger particles can be separated from the sought-after nano-scale particles through the use of the cyclonic separator or because of their differing deposition rates on a collector. [0038] Therefore it is an object of the present invention to provide a process and apparatus for the production of nano-scale metal particles. [0039] It is another object of the present invention to provide a process and apparatus capable of producing nano-scale metal particles under conditions of temperature and/or pressure less extreme than conventional processes. [0040] It is still another object of the present invention to provide a process for preparing nano-scale metal particles which can be directly deposited on the end use substrate. [0041] It is yet another object of the present invention to provide a process for preparing nano-scale metal particles which can be collected for further use or treatment. [0042] It is a further object of the present invention to provide chain agglomerations of nano-scale metal particles. [0043] These objects and others which will be apparent to the skilled artisan upon reading the following description, can be achieved by providing a process and apparatus for producing nano-scale metal particles, including providing a reactor vessel; feeding at least one decomposable moiety selected from the group of organometallic compounds, metal complexes, metal coordination compounds, and mixtures thereof into a reactor vessel; exposing the decomposable moiety within the reactor vessel to a source of energy sufficient to decompose the moiety and produce nano-scale metal particles; and deposit or collection of the nano-scale metal particles. Preferably, the temperature within the reactor vessel is no greater than about 250° C. The pressure within the reactor vessel is preferably generally atmospheric, but pressures which vary between about 1 mm to about 2000 mm can be employed. [0044] The reactor vessel is advantageously formed of a material which is relatively transparent to the energy supplied by the source of energy, as compared to either the collector on which the nano-scale metal particles are collected or the decomposable moieties, such as where the source of energy is radiant heat. In fact, the support or collector can have incorporated therein a resistance heater, or the source of energy can be a heat lamp. Where the source of energy is radiant heat, the reactor vessel can be cooled, such as by a cooling medium like cooling coils or a cooling jacket disposed about the reactor vessel to preclude decomposition of the moiety and deposit of particles at the vessel walls. [0045] The support can be the end use substrate for the nano-scale metal particles produced, such as a component of an automotive catalytic converter or a fuel cell or electrolysis membrane or electrode. The support or collector can be positioned within the reactor vessel. However, the reactor vessel can be a flow-through reactor vessel comprising a conduit, and in such case the support or collector can be disposed either external to the reactor vessel or within the reactor vessel. [0046] It is to be understood that both the foregoing general description and the following detailed description present embodiments of the invention, and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. [0047] The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate various embodiments of the invention, and together with the description serve to explain the principles and operations of the invention. BRIEF DESCRIPTION OF THE DRAWINGS [0048] FIG. 1 is a side plan view of an apparatus for the production of nano-scale metal particles utilizing a “closed system” reactor vessel in accordance with the present invention. [0049] FIG. 2 is a side plan view of an alternate embodiment of the apparatus of FIG. 1 . [0050] FIG. 3 is a side plan view of an apparatus for the production of nano-scale metal particles utilizing a “flow-through” reactor vessel in accordance with the present invention. [0051] FIG. 4 is an alternative embodiment of the apparatus of FIG. 3 . [0052] FIG. 5 is another alternative embodiment of the apparatus of FIG. 3 , using a support external to the flow-through reactor vessel. [0053] FIG. 6 is a photomicrograph of a chain agglomeration of nano-scale metal particles in accordance with the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0054] Referring now to the drawings, an apparatus in which the inventive process for the production of nano-scale metal particles can be practiced is generally designated by the numeral 10 or 100 . In FIGS. 1 and 2 apparatus 10 is a closed system comprising closed reactor vessel 20 whereas in FIGS. 3-5 apparatus 100 is a flow-through reaction apparatus comprising flow-through reactor vessel 120 . [0055] It will be noted that FIGS. 1-5 show apparatus 10 , 100 in a certain orientation. However, it will be recognized that other orientations are equally applicable for apparatus 10 , 100 . For instance, when under vacuum, reactor vessel 20 can be in any orientation for effectiveness. Likewise, in flow-through reactor vessel 120 , the flow of inert carrier gas and decomposable moieties or the flow of decomposable moieties as drawn by a vacuum in FIGS. 3-5 can be in any particular direction or orientation and still be effective. In addition, the terms “up” “down” “right” and “left” as used herein refer to the orientation of apparatus 10 , 100 shown in FIGS. 1-5 . [0056] Referring now to FIGS. 1 and 2 , as discussed above apparatus 10 comprises a closed-system reactor vessel 20 formed of any material suitable for the purpose and capable of withstanding the exigent conditions for the reaction to proceed inside including conditions of temperature and/or pressure. Reactor vessel 20 includes an access port 22 for providing an inert gas such as argon to fill the internal spaces of reactor vessel 20 , the inert gas being provided by a conventional pump or the like (not shown). Similarly, as illustrated in FIG. 2 , port 22 can be used to provide a vacuum in the internal spaces of reactor vessel 20 by using a vacuum pump or similar device (not shown). In order for the reaction to successfully proceed under vacuum in reactor vessel 20 , it is not necessary that an extreme vacuum condition be created. Rather negative pressures no less than about 1 mm, preferably no less than about 250 mm, are all that are required. [0057] Reactor vessel 20 has disposed therein a support 30 which can be attached directly to reactor vessel 20 or can be positioned on legs 32 a and 32 b within reactor vessel 20 . Reactor vessel 20 also comprises a sealable opening shown at 24 , in order to permit reactor vessel 20 to be opened after the reaction is completed to remove support 30 or remove nano-scale metal particles deposited on support 30 . Closure 24 can be a threaded closure or a pressure closure or other types of closing systems, provided they are sufficiently air tight to maintain inert gas or the desired level of vacuum within reactor vessel 20 . [0058] Apparatus 10 further comprises at least one feeder 40 , and preferably a plurality of feeders 40 a and 40 b , for feeding reactants, more specifically the decomposable moiety, into reactor vessel 20 . As illustrated in FIGS. 1 and 2 , two feeders 40 a and 40 b are provided, although it is anticipated that other feeders can be employed depending on the nature of the decomposable moiety/moieties introduced into vessel 20 and/or end product nano-scale metal particles desired. Feeders 40 a and 40 b can be fed by suitable pumping apparatus for the decomposable moiety such as venturi pumps or the like (not shown). [0059] As illustrated in FIG. 1 , apparatus 10 further comprises a source of energy capable of causing decomposition of the decomposable moiety. In the embodiment illustrated in FIG. 1 , the source of energy comprises a source of heat, such as a heat lamp 50 , although other radiant heat sources can also be employed. In addition, as discussed above, the source of energy can be a source of electromagnetic energy, such as infrared, visible or ultraviolet light, microwave energy, radio waves or other forms of sonic energy, as would be familiar to the skilled artisan, provided the energy employed is capable of causing decomposition of the decomposable moiety. [0060] In one embodiment, the source of energy can provide energy that is preferentially couple-able to support 30 so as to facilitate deposit of nano-scale metal particles produced by decomposition of the decomposable moiety on support 30 . However, where a source of energy such as heat is employed, which would also heat reactor vessel 20 , it may be desirable to cool reactor vessel 20 using, e.g., cooling tubes 52 (shown partially broken away) such that reactor vessel 20 is maintained at a temperature below the decomposition temperature of the decomposable moiety. In this way, the decomposable moiety does not decompose at the surfaces of reactor vessel 20 but rather on support 30 . [0061] In an alternative embodiment illustrated in FIG. 2 , support 30 itself comprises the source of energy for decomposition of the decomposable moiety. For instance, a resistance heater powered by connection 34 can be incorporated into or comprise support 30 such that only support 30 is at the temperature of decomposition of the decomposable moiety, such that the decomposable moiety decomposes on support 30 and thus produces nano-scale metal particles deposited on support 30 , such as the chain agglomeration of nano-scale metal particles shown in FIG. 6 . Likewise, other forms of energy for decomposition of the decomposable moiety can be incorporated into support 30 . [0062] Support 30 can be formed of any material sufficient to have deposit thereon of nano-scale metal particles produced by decomposition of the decomposable moiety. In a preferred embodiment, support 30 comprises the end use substrate on which the nano-scale metal particles are intended to be employed, such as the aluminum oxide or other components of an automotive catalytic converter, or the electrode or membrane of a fuel cell or electrolysis cell. Indeed, where the source of energy is itself embedded in or associated with support 30 , selective deposition of the catalytic nano-scale metal particles can be obtained to increase the efficiency of the catalytic reaction and reduce inefficiencies or wasted catalytic metal placement. In other words, the source of energy can be embedded within support 30 in the desired pattern for deposition of catalyst metal, such that deposition of the catalyst nano-scale metal can be placed where catalytic reaction is desired. [0063] In another embodiment of the invention, as illustrated in FIGS. 3-5 , apparatus 100 comprises a flow-through reactor vessel 120 which includes a port, denoted 122 , for either providing an inert gas or drawing a vacuum from reactor vessel 120 to thus create flow for the decomposable moieties to be reacted to produce nano-scale metal particles. In addition, apparatus 100 includes feeders 140 a , 140 b , 140 c , which can be disposed about the circumference of reactor vessel 102 , as shown in FIG. 3 , or, in the alternative, sequentially along the length of reactor vessel 120 , as shown in FIG. 4 . [0064] Apparatus 100 also comprises support 130 on which nano-scale metal particles are collected. Support 130 can be positioned on legs 132 a and 132 b or, in the event a source of energy is incorporated into support 130 , as a resistance heater, the control and wiring for the source of energy in support 130 can be provided through line 134 . [0065] As illustrated in FIGS. 3 and 4 , when support 130 is disposed within flow-through reactor vessel 120 , a port 124 is also provided for removal of support 130 or the nano-scale metal particles deposited thereon. In addition, port 124 should be structured such that it permits the inert gas fed through port 122 and flowing through reactor vessel 120 to egress reactor vessel 120 (as shown in FIG. 3 ). Port 124 can be sealed in the same manner as closure 24 discussed above with respect to closed system apparatus 10 . In other words, port 124 can be sealed by a threaded closure or pressure closure or other types of closing structures as would be familiar to the skilled artisan. [0066] As illustrated in FIG. 5 , however, support 130 can be disposed external to reactor vessel 120 in flow-through reactor apparatus 100 . While support 130 can be a cyclonic or centrifugal collector (not shown), it can also be a structural support 130 as illustrated in FIG. 5 . In this embodiment, flow-through reactor vessel 120 comprises a port 124 through which decomposable moieties are impinged on support 130 to thus deposit the nano-scale metal particles on support 130 . In this way it is no longer necessary to gain access to reactor vessel 120 to collect either support 130 or the nano-scale metal particles deposited thereon. In addition, during the impingement of the decomposable moieties to produce nano-scale metal particles on support 130 , either port 126 or support 130 can be moved in order to provide for an impingement of the produced nano-scale metal particles on certain specific areas of support 130 . This is especially useful if support 130 comprises the end use substrate for the nano-scale metal particles such as the component of a catalytic converter or electrode for fuel cells. Thus, the nano-scale metal particles are only produced and deposited where desired and efficiency and decrease of wasted catalytic metal is facilitated. [0067] As discussed above, reactor vessel 20 , 120 can be formed of any suitable material for use in the reaction provided it can withstand the temperature and/or pressure at which decomposition of the decomposable moiety occurs. For instance, the reactor vessel should be able to withstand temperatures up to about 250° C. where heat is the energy used to decompose the decomposable moiety. Although many materials are anticipated as being suitable, including metals, plastics, ceramics and materials such as graphite, preferably reactor vessels 20 , 120 are formed of a transparent material to provide for observation of the reaction as it is proceeding. Thus, reactor vessel 20 , 120 is preferably formed of quartz or a glass such as Pyrex® brand material available from Corning, Inc. of Corning, N.Y. [0068] In the practice of the invention, either a flow of an inert gas such as argon or nitrogen or a vacuum is drawn on reactor vessel 20 , 120 and a stream of decomposable moieties is fed into reactor vessel 20 , 120 via feeders 40 a , 40 b , 140 a , 140 b , 140 c . The decomposable moieties can be any metal containing moiety such as an organometallic compound, a complex or a coordination compound, which can be decomposed by energy at the desired decomposition conditions of pressure and temperature. For instance, if heat is the source of energy, the decomposable moiety should be subject to decomposition and production of nano-scale metal particles at temperatures no greater than 300° C., more preferably no greater than 200° C. Other materials, such as oxygen, can also be fed into reactor 20 , 120 to partially oxidize the nano-scale metal particles produced by decomposition of the decomposable moiety, to modify the surface of the nano-scale particles. Contrariwise, a reducing material such as hydrogen can be fed into reactor 20 , 120 to reduce the potential for oxidation of the decomposable moiety. [0069] The energy for decomposition of the decomposable moiety is then provided to the decomposable moiety within reactor vessel 20 , 120 by, for instance, heat lamp 50 , 150 . If desired, reactor vessel 120 can also be cooled by cooling coils 52 , 152 to avoid deposit of nano-scale metal particles on the surface of reactor vessel 20 , 120 as opposed to support 30 , 130 . Nano-scale metal particles produced by the decomposition of the decomposable moieties are then deposited on support 30 , 130 or, in a cyclonic or centrifugal or other type collector, for storage and/or use. [0070] As discussed, it is often desirable to produce chain agglomerations of nano-scale metal particles, when the end use application is catalysis or the like. A representative chain agglomeration is shown in the photomicrograph of FIG. 6 ; the chain agglomeration of FIG. 6 is an agglomeration of nano-scale nickel and iron particles, at a ratio of nickel to iron of about 6.5:1, shown 250,000 times its actual size. As is apparent, the chain agglomeration of FIG. 6 has an aspect ratio of at least about 1000:1. [0071] To produce a chain agglomeration such as the one shown in FIG. 6 , a vacuum of about is drawn on reactor vessel 20 , 120 and a stream of decomposable moieties, such as nickel and iron carbonyls, at a partial pressure of less than 500 mm, is fed into reactor vessel 20 , 120 via feeders 40 a , 40 b , 140 a , 140 b , 140 c . An inert gas such as nitrogen can also be fed into reactor 20 , 120 , at a partial pressure of less than about 700 mm. Moiety pressures of less than about 80 mm are all that is required. The process time for production of chain agglomerations such that shown in FIG. 6 is less than about 3 seconds. [0072] The energy for decomposition is heat support 30 , 130 , such as a resistively heated wire. Chain agglomerations of nano-scale metal particles produced by the decomposition of the decomposable moieties are then deposited on support 30 , 130 , and can be collected, for storage and/or use. [0073] Thus the present invention provides a facile means for producing nano-scale metal particles which permits selective placement of the particles, direct deposit of the particles on the end use substrate, without the need for extremes of temperature and pressure required by prior art processes. [0074] All cited patents, patent applications and publications referred to herein are incorporated by reference. [0075] The invention thus being described, it will be apparent that it can be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the present invention and all such modifications as would be apparent to one skilled in the art are intended to be included within the scope of the following claims.

A process and apparatus for producing chain agglomerations of nano-scale metal particles includes feeding at least one decomposable moiety selected from the group consisting of organometallic compounds, metal complexes, metal coordination compounds and mixtures thereof into a reactor vessel; exposing the decomposable moiety to a source of energy sufficient to decompose the moiety and produce nano-scale metal particles; and deposit or collection of chain agglomerations of nano-scale metal particles.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to night vision systems, and more particularly, to an improved night vision weapon sight. 2. Description of Related Art Military and law enforcement personnel which use weapons, such as rifles, have long sought ways to improve their aim. By improving their shooting accuracy, these personnel increase their own effectiveness and survivability, while minimizing the possibility of innocent bystanders being inadvertently shot. The typical rifle is provided with a mechanical sight which is aligned to the barrel of the rifle. The operator visually aligns the mechanical sight with the desired target by peering down the barrel. Since the desired target cannot be observed accurately at night, night vision systems are commonly used as night vision weapon sights. These systems employ an image intensification process which amplifies the ambient light reflected or emitted by an observed object. The image intensification process involves conversion of the received ambient light into electron patterns and projection of the electron patterns onto a phosphor screen for conversion of the electron patterns into light visible to the observer. This visible light is then viewed by the operator through a lens provided in an eyepiece of the night vision system. The night vision weapon sight is often equipped with a high power magnification, such as three times magnification (3X). Instead of using the mechanical sight, internal sighting systems can be incorporated into the night vision sight. These sighting systems utilize a light source which is superimposed over the viewed image to provide an aim point, or reticle. The light source is aligned, or boresighted, to the barrel of the weapon, so that it designates the point which would be struck by a bullet fired from the weapon. The operator uses the night vision sight by overlaying the reticle over the image of the desired target viewed through the sight. Night vision sights having internal aiming reticles can enable an operator to accurately strike a distant target during low light conditions. In typical night vision systems, an objective lens forms an inverted image on an internal image intensifier tube, which performs the image intensification process. In order for the system to present the user with an upright image, the image intensifier tube inverts the image. An inverting intensifier tube contains a fused fiber optic slug with a 180 degree twist. The eyepiece is non-inverting, and provides magnification of the image as desired by the user. Range focusing of the night vision weapon sight is accomplished by changing the relative distance between the objective lens and the image intensifier tube. Non-inverting image intensifier tubes are used in other types of night vision systems, such as binoculars using a single image tube. For example, see U.S. Pat. No. 4,266,129, issued to Versteeg et al. However, non-inverting tubes have not heretofore been used in night vision sights since compatibility with traditional non-inverting eyepieces is desired. The least expensive and most uncomplicated eyepiece design is non-inverting; use of an inverting eyepiece causes the overall length of the sight to increase due to the addition of an inverting lens. Therefore, commercially available inverting image intensifier tubes were traditionally used in conjunction with non-inverting eyepieces in night vision weapon sight applications. One problem experienced with such prior art night vision weapon sights is that of degraded aiming accuracy due to inadvertent motion of the inverting image intensifier tube. If the tube position is shifted laterally off-axis while the input image is held fixed, the output image will also shift laterally in the opposite direction. Slight lateral movement can unintentionally occur during focusing of the night vision sight, or by the mechanical shock of firing the weapon. Non-inverting tubes are insensitive to the lateral shift; if the tube position is shifted laterally while the input image is held fixed, the output image will remain fixed. In all night vision aiming systems, it is desirable to have the aiming reticle be a contrasting color to the tube output image so that the reticle will be easy to distinguish from the scene. However, for the reticle to be a contrasting color, the reticle image must be inserted after the image intensifier tube and before the eyepiece. Therefore, any lateral movement of the tube output image will appear as a false apparent movement with respect to the reticle image. Since aiming reticles are often boresighted to a weapon with 0.1 milliradians accuracy, even slight false image movement of as little as 10 micrometers would invalidate the weapon boresight. This problem could be alleviated by injecting the reticle image before the image intensifier tube. This way, the reticle and tube output image would move together. However, this approach diminishes the image contrast advantages described above. Moreover, the brightness of the reticle tends to "wash out" the scene images adjacent to the reticle, and can potentially even "burn" the reticle image permanently into the image intensifier tube. Thus, the disadvantages of this solution significantly outweigh the benefits. Lateral movement of the image intensifier tube can be avoided by rigidly mounting the tube and reticle together, and move only the objective lens at the front end of the sight for focusing. Rotation of the lens causes it to move inward or outward relative to the image intensifier tube depending on the direction of rotation. Alternatively, a threaded ring could be provided which drives the lens without rotating the lens. A spring loaded rack and pinion or cam disposed on a shaft orthogonal to the optical axis could also be used. Nevertheless, these focusing methods often involve slight lateral shifts of the objective lens, which moves the scene image in the same manner as when the inverting image intensifier tube is shifted laterally. Thus, the same potential for aiming inaccuracy exists, and the problem has merely been transferred from the image intensifier tube to the objective lens. An additional problem experienced with night vision sights which use image intensifier tube movement for range focusing is that of dioptric shift at the eyepiece. The eyepiece optics can be adjusted to accommodate the particular diopter of the operator's eye. Once the eyepiece has been properly adjusted, any movement of the focal plane of the image intensifier tube during range focusing would upset the diopter adjustment. To prevent the dioptric shift, the eyepiece can be movable in unison with the image intensifier tube. However, this renders the night vision weapon sight difficult to operate, since the operator would have to shift his eye position to accommodate each range change. Furthermore, movement of the objective lens requires greater mechanical advantage than corresponding movement of the image intensifier tube. To allow a maximum amount of light into the sight, a large diameter objective lens is often utilized. Rotation of the lens can be cumbersome if the lens or threaded ring is large and awkward to grasp and rotate. Additionally, the lens must have sufficient internal friction so as to be intentionally difficult to rotate, and prevent unintended rotation out of adjustment due to axial shock experienced from firing the weapon. To rotate the lens, an operator must use a substantial amount of torque, requiring that a counter rotational force be applied to the instrument or to the weapon so as not to introduce cant to the alignment of the system. Besides, rotation of the lens is additionally undesirable since it could introduce unacceptable circular movement of the image viewed through the eyepiece of the sight. A secondary problem also arises from the large size of the objective lens. The sight must be mounted on the weapon at a height sufficient to accommodate the lens size. As a result, the eyepiece of the sight would often be at a height which could be uncomfortable for the user. Weapons operators are trained to use their weapon with the mechanical sight provided with the weapon, which is typically mounted in close proximity to the top of the weapon barrel. These weapon operators practice firing their weapons with their head positioned to see the target and the mechanical sight concurrently. When the night vision sight is incorporated onto the weapon, the operators have to place their head in a different position to compensate for the higher eyepiece. Despite the inherent advantages of the night vision sight, many operators find them uncomfortable to use and less accurate because of the sight's awkward position. This particular problem has been addressed in the prior art by U.S. Pat. No. 4,582,400, issued to Lough. The '400 patent discloses a night vision sight having an eyepiece disposed at an offset position which corresponds to the line of sight of the mechanical sight provided with the weapon. However, the Lough patent has a flaw which would render the design inoperable. In projecting the image to the eyepiece, the optical chain of the '400 patent repeatedly and unnecessarily inverts the image. The image is first inverted by the objective lens, and then inverted back to the upright configuration by the image intensifier tube. An additional lens in the eyepiece inverts the image once again, so that the final image presented to the operator remains inverted. Either the collimating lens after the image intensifier tube inverts the image as well, which adds unnecessary complexity to the scope, or the reference intends to present an inverted image to the operator. The '400 patent would be enabling if either a non-inverting eyepiece or a non-inverting image intensifier tube were used, although neither of these solutions were suggested in the reference. Another problem experienced by users of night vision sights is that of calibrating the reticle. Ideally, the reticle should be positioned to precisely designate the target viewed through the night vision sight. However, the accuracy of the weapon can vary greatly due to external factors, such as windage and distance. A weapon operator is trained in making adjustments to the mechanical sight in azimuth and elevation to compensate for these external factors. To adjust a reticle of a night vision sight, an operator physically moves a reticle light source along X and Y coordinates until a desired position is reached. This procedure can lead to inaccuracies since it is difficult to isolate the two measurements; often an adjustment to elevation results in inadvertent alteration to azimuth. The reticle position can also be influenced by shock or impact due to the weapon firing. As an additional problem, the reticle pattern may tend to rotate relative to the viewed image, which can disorient the operator. Thus, it would be desirable to provide a night vision sight having an accurate and stable focusing system which does not require the operator to manipulate the objective lens. It would also be desirable to provide a night vision sight having improved aiming accuracy due to insensitivity to lateral movement of the image intensifier tube during focusing. It is additionally desired to provide a night vision sight having a simplified eyepiece which is offset to the line of sight of the mechanical sight typically provided with a weapon. It would also be desirable to provide a night vision sight which allows the reticle to be adjusted independently in azimuth and elevation. SUMMARY OF THE INVENTION Accordingly, a principal object of the present invention is to provide a night vision sight having a focusing mechanism in which the position of the image intensifier tube is varied rather than the objective lens. Another object of the present invention is to provide a night vision sight using a non-inverting image intensifier tube which is insensitive to lateral movement and permits improved aiming accuracy. Another object of the present invention is to provide a night vision sight having an offset eyepiece which is positioned equivalent to the mechanical sight provided with the weapon, and which has a simplified optical path as compared with the prior art. Yet another object of the present invention is to provide a night weapon sight having a reticle which is adjustable independently in elevation and in azimuth. To achieve the foregoing objects, and in accordance with the purpose of the invention, a night vision sight is provided for use with a weapon, which includes an objective lens and an image intensifier tube disposed along an optical axis, providing an intensified target image. The sight is focused by direct movement of the image intensifier tube relative to the fixed position of the objective lens. A reticle projector is disposed orthogonal to the optical axis and provides a collimated reticle image, the reticle image providing an aiming point for the weapon. The reticle image is superimposed over the target image, and the combined image reflected into an eyepiece of the sight. The eyepiece has a viewing axis between the optical axis and a sight line passing through a pre-existing sight provided with the weapon. Adjustment of the apparent position of the reticle to compensate for azimuth and elevation is accomplished by moving the reticle projector about crossed cylindrical bearings. More specifically, a focusing assembly for a night vision system is provided in which the objective lens is fixed and the image intensifier tube is moveable along the optical axis of the objective lens. A focus knob is affixed to a threaded worm shaft which is mounted transverse to the optical axis. A ring gear is rotatable around the optical axis in mating engagement with the worm shaft. A side surface of the gear has a plurality of axially extending ramp surfaces. The image intensifier tube also has a plurality of opposing ramp surfaces in facing contact with the ramp surfaces of the ring gear. A spring biases the image intensifier tube in order to maintain contact between the ramp surfaces. The image intensifier tube changes position along the optical axis by the intentional rotation of the focus knob and the corresponding rotation of the ring gear. The ramp surfaces of the ring gear rotate about the optical axis and change their contact point with the opposing ramp surfaces, which applies an axial force to reposition the image intensifier tube. The image intensifier tube is constrained to prevent its rotation. The night vision sight provides a non-inverting image intensifier tube disposed along an optical axis which provides an intensified target image. A reticle projector is disposed orthogonal to the optical axis and provides a collimated reticle image. The reticle image provides an aiming point for the weapon. A dichroic filter is disposed at a 45 degree angle to the optical axis. The filter reflects the intensified image and transmits the reticle image. A relay lens combines the target image and the reticle image into a single combined image. A mirror reflects the combined image into an eyepiece of the sight. The eyepiece is disposed at a position relative to the weapon equivalent to that of the pre-existing mechanical sight typically provided with the weapon. The apparent position of the reticle image relative to the intensified image can be translated to calibrate the sight in elevation and in azimuth. An elevational cylindrical bearing permits pivotal movement of the reticle projector in a first direction, and an azimuthal cylindrical bearing permits pivotal movement of the reticle projector in a second general direction which is perpendicular to the first direction. Controlled movement of the reticle projector in either of these general directions varies the apparent position of the reticle image relative to the intensified image. A more complete understanding of the night vision weapon sight of the present invention will be afforded to those skilled in the art, as well as a realization of additional advantages and objects thereof, by consideration of the following Detailed Description of the Preferred Embodiment. Reference will be made to the appended sheets of drawings which will be first described briefly. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a perspective view of an improved night vision weapon sight of the present invention; FIG. 2 is a sectional view of the night vision weapon sight as in FIG. 1, showing the adjustment assembly for range focusing; FIG. 3 is a side view of the night vision sight affixed to an exemplary rifle; FIG. 4 is an exploded view of an adjustment assembly providing optical focusing for the night vision weapon sight; FIG. 5 is a sectional side view of the night vision weapon sight showing the offset eyepiece; FIG. 6 is a sectional rear view of the night vision weapon sight; and FIG. 7 is an exploded view of the night vision weapon sight in relation to the handle of the weapon. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIGS. 1 and 3, there is shown a night vision weapon sight 10 of the present invention. The weapon sight 10 is secured to a weapon 8 to a handle portion 11 disposed above the weapon's barrel 7. The weapon 8 shown is an M-16 rifle, however, it should be apparent that the night vision sight 10 of the present invention can be advantageously used with a wide assortment of other types of weapons. The handle portion 11 has a mechanical weapon sight comprising a rear sight 12 aligned to a front sight 13, which would typically provide the sight line 14 for the weapon in the absence of the night vision weapon sight 10. The sight line 14 through the mechanical weapon sights 12 and 13 is calibrated to intersect with the path of the bullet at the intended target. The operator of the weapon 8 typically views along the sight line 14 in order to aim the weapon at the desired target. The night vision weapon sight 10 enables the operator to accurately sight the weapon at a desired target during conditions of darkness. The weapon sight 10 is provided within a system housing 20, as will be further described below. Ambient light emitted or reflected from a viewed scene enters an objective lens 16 at the forward portion of the system housing 20. The received light image is amplified by an image intensifier tube within the sight 10, and a reticle image overlaid upon the intensified image. This resulting image is then viewed by the operator through an offset eyepiece 70 disposed at a rear portion of the system housing 20. Referring now to FIGS. 2 and 4, there is shown an adjustment assembly which enables focusing of the night vision weapon sight 10. The objective lens 16 has a relatively large diameter and an optical axis 18. The lens is formed within a lens housing 17, and remains in a fixed position relative to the system housing 20. Light from a scene is projected through the objective lens 16 onto an image intensifier tube 22 which forms an intensified image of the scene. As will be described below, focusing of the night vision sight is provided by axial movement of the image intensifier tube, rather than movement of the objective lens 16. By moving axially the image intensifier tube 22 relative to the fixed objective lens 16, the focal point in the plane of the image intensifier 22 corresponds to objects of varying distance. Axial movement of the image intensifier tube 22 without rotation of the image intensifier tube is accomplished by use of a ring gear 24, a threaded worm shaft 34 and opposed ramp surfaces 28 and 42. The ring gear 24 is rotatable around the optical axis 18 and has protruding teeth 25 surrounding the outer surface of the gear. The teeth mechanically engage a threaded portion 36 of a worm gear shaft 34. An end of the shaft 34 extends outwardly from the system housing 20 and engages a knob 32. Rotation of the knob 32 causes direct rotation of the ring gear 24 by the mechanical engagement between the worm gear 34 and the ring gear. The ring gear 24 is disposed between the objective lens 16 and the image intensifier tube 22. A side surface of the ring gear 24 which faces the image intensifier tube 22 has a plurality of ramp extensions 26. These ramp extensions 26 have ramp surfaces 28 which are diagonally disposed relative the optical axis 18. In the preferred embodiment, there are four such ramp extensions 26 evenly spaced upon the side surface of the ring gear 24, and each of the ramp surfaces 28 have a relatively shallow slope angle relative the side surface 30 of approximately 20 degrees. In facing engagement with the ramp extensions 26, are a plurality of opposing ramp extensions 40. The opposing ramp extensions 40 are equivalent in size and displacement to the ramp extensions 26 described above, having opposing ramp surfaces 42 equivalent to the ramp surfaces 28. The opposing ramp extensions 40 are disposed so that the ramp surfaces 28 are in facing contact with the opposing ramp surfaces 42. The ramp extensions 40 extend from a forcing ring 38 disposed between the image intensifier tube and the ring gear 24. The forcing ring 38 is secured to the image intensifier tube 22, and moves the tube axially by force applied by the rotating ring gear 24. The image intensifier tube 22 is prevented from rotation by use of a guide channel 23 disposed in an outer surface of the tube 22. The guide channel 23 is engaged by a pin (not shown) extending outwardly from an internal portion of the system housing 20. Thus, the image intensifier tube 22 can move axially along the optical axis 18 by the pin riding within the guide channel 23, but the tube cannot be rotated. To maintain positive pressure between the ramp surfaces 28 and 42, a spring 48 is disposed at an opposite end of image intensifier tube 22. The ring gear 24 is secured in position within the system housing 20 to preclude either lateral or axial movement of the ring gear 24. The objective lens housing 17 has an adapter end 19 which can be mechanically secured to the system housing 20 by screws, bolts or other known fastening devices. An inner portion of the adapter end 19 forms a retaining wall 21 in contact with a side surface of the ring gear 24 which faces the objective lens 16. The contact between the retaining wall 21 and the ring gear 24 prevents axial movement of the ring gear. The forcing ring 38 has an inner sleeve 37 which extends from an inside portion of the ring. The inner sleeve 37 extends into and rotates within the inside surface 29 of the ring gear 24. Since the forcing ring 38 is secured to the image intensifier tube 22, and lateral motion of the tube is precluded by its contact with the inner portion of the system housing 20, lateral motion of the ring gear is prevented. The adjustment assembly easily enables an operator to adjust the focusing of the night vision weapon sight 10. To change the axial position of the image intensifier tube 22 along the optical axis 18, an operator rotates the knob 32. Rotation of the knob 32 causes direct rotation of the ring gear 24, which in turn causes the ramp surfaces 28 to rotate relative to the opposing ramp surfaces 42. The engagement between the ring gear 24 and the worm gear 34 provides sufficient mechanical advantage to enable easy rotation of the knob 32 and consequent movement of the image intensifier tube 22. It should be apparent that the adjustment assembly of the present invention would additionally be suitable for any sort of optical lens focusing which requires axial movement of an optical member along an optical axis without permitting rotation of the optical member about the axis. In the present invention, it is anticipated that the image intensifier tube be non-inverting. Referring to FIGS. 5 and 7, the objective lens 16 projects an inverted image of the scene onto the image intensifier tube 22. Thus, the intensified image produced by the non-inverting image intensifier tube 22 remains inverted. To return the image to the upright configuration, the image must be inverted a second time. The second inversion step occurs in the relaying optics, which will be described below. After the image has been intensified by the image intensifier tube 22, the intensified image then must be combined with a reticle and presented to the operator. Since range focusing is accomplished by moving the image intensifier tube 24 rather than the objective lens 16, and it is desired to have contrast between the reticle image and the intensified image, the intensified image must be collimated and combined with a collimated reticle image. First, the intensified image is projected through a collimating lens 60 provided in a collimator assembly 61. The collimator assembly 61 is mounted to the image intensifier tube 22, and travels with it during focusing. By collimating the intensified image, readjustment to the diopter setting of the eyepiece 70 is unnecessary. The collimating lens 60 produces an image which appears to be projected at an infinite distance. As will be further explained below, a collimated reticle image is overlaid onto the collimated intensified image. By injecting the collimated reticle image after the image intensifier tube 22 and collimating lens 60, the reticle image maintains good contrast with the viewed scene, and avoids the problems of "wash out" and image burning described above. Referring to FIG. 5, a reticle projector 50 produces a collimated image of a reticle which is aligned to the barrel of the weapon 8. The reticle projector 50 has a red light emitting diode (LED) 52 which provides a light source for the reticle. Red light from the LED 52 projects onto a glass plate 54. A first side 56 of the glass plate 54 is frosted or ground to provide a generally rough surface, which produces diffused light transmission through the plate 54. An opposite side 58 of the plate 54 is plated with a metallic alloy. The plated surface 58 can then be selectively etched to form a desired pattern for the reticle image. Light which passes through the plated surface 58 is collimated by a lens group 62 within the reticle projector 50. A housing 51 combines the elements of the reticle projector 50 into an enclosed cylinder. The collimated reticle image produced by the reticle projector 50 will be combined with the collimated intensified image for presentation to the operator, as will be described below. The selective etching of the plated surface 58 can produce a wide assortment of desired reticle image patterns, such as "cross hairs", "bull's eye", or the image of objects such as tanks, vehicles, or personnel. As known in the art, the etched image selected would correspond with the type of weapon used or the particular mission which the operator performs. It is necessary that the reticle image be manipulated so as to calibrate the reticle to the weapon 8 for windage and elevation. The entire reticle projector 50 is rotatable about two axis, in order to perform the necessary adjustment. A first cylindrical bearing 86 permits the reticle projector 50 to be pivoted in elevation. In addition, a second cylindrical bearing 98 is provided to permit the reticle projector 50 to be pivoted in azimuth. The two cylindrical bearings 86 and 98 are nested, and disposed within non-intersecting, perpendicular axes. It should be apparent to that the two cylindrical bearings 86 and 98 are sufficiently independent so that an adjustment to one would not effect the setting of the other. The bearings 86 and 98 are generally cylindrical in shape, having windows in a central portion to permit the passage of light. Load springs 97 are additionally provided, which maintain a positive pressure on the bearings 86 and 98. The springs 97 join the reticle projector housing 51 with the internal support structure of the system housing 20 adjacent to the bearing 98. To adjust the reticle projector relative to the cylindrical bearings, adjustment mechanisms for azimuth and elevation are provided. An elevation knob 76 can be rotated by an operator to depress or raise a plunger 78. The plunger 78 acts upon an arm 84 secured to the reticle projector 50. A pressure spring 82 provides an opposing pressure against the plunger 78 to maintain the arm 84 in contact with the plunger. As the elevation knob 76 is manually rotated, the plunger 78 can be selectively extended to force the reticle projector 50 to pivot about the elevational bearing 86. Similarly, an azimuth adjustment knob 88 is provided which joins to a plunger 92, as shown in FIG. 6. The plunger 92 acts directly upon the housing 51 of the reticle projector 50, with a pressure spring 94 provided on an opposite side of the reticle projector. Rotation of the azimuth adjust knob 88 causes the plunger 92 to selectively extend so as to pivot the reticle projector 50 about the azimuth cylindrical bearing 98. To combine the collimated intensified image with the collimated reticle image, and present the combined image to the operator, relaying optics are provided. The relaying optics include a dichroic filter 64, a relay lens 66 and a relay mirror 68. The dichroic filter 64 is disposed at a 45° angle to the optical axis 18. The relay lens 66 receives the combined images and forms an inverted intermediate image. The relay mirror 68 reflects the image produced by the relay lens 66 into the eyepiece cell 70. The relay mirror 68 is disposed at a 45° to an offset line of sight 74, and faces toward the dichroic filter 64. As known in the art, the dichroic filter 64 is wavelength selective so as to reflect light emitted by the image intensifier tube 22, and to transmit the reticle image produced by the reticle projector 50. The dichroic filter 64 is formed of one or more dielectric layers coated onto a suitable transparent substrate. The light emitted from the image intensifier tube 22 is generally in the green range of the light spectrum, while the reticle image produced by the reticle projector 50 is in the red spectral region. The dichroic filter 64 would transmit more than 70% of the red light and reflect greater than 90% of the green light. A cutoff point for the dichroic filter 64 is selected to maximize reflectance of the light from the image intensifier tube 22, since the light from the LED can be easily increased to an acceptable level. Thus, light which reaches the relay lens 66 is a combination of the reticle image and the intensified image. In the present invention, the offset eyepiece cell 70 is utilized to present the intensified image to the operator at the line of sight 74 which approximates that of the mechanical gun sight 12. The eyepiece cell 70 has one or more internal lenses 72 which can be used by the operator to further magnify the viewed image. As known in the art, the eyepiece cell 70 has an eyecup 75 which provides a shroud for light security surrounding the operator's eye and preventing the sight's green light glow from being seen by other forces similarly using night vision equipment. In the preferred embodiment, a commercially available eyepiece cell 70 as used in other day or night sights would be utilized. This has the advantages that the operator is already familiar with use of the eyepiece cell, and that manufacturing costs can be minimized. Having thus described a preferred embodiment of the night vision weapon sight, it should now be apparent to those skilled in the art that the aforestated objects and advantages for the within system have been achieved. It should also be appreciated by those skilled in the art that various modifications, adaptations and alternative embodiments thereof may be made within the scope and spirit of the present invention. For example, the focusing mechanism can be advantageously used in any application requiring axial movement of a cylindrical member. The offset eyepiece could be rotated so that the eyepiece is offset laterally relative to the weapon, or perpendicular to the weapon. The night vision weapon sight can be used with a wide assortment of weapons. The present invention is further defined by the following claims:

A night vision sight is provided for use with a weapon, which includes an objective lens and a non-inverting image intensifier tube disposed along an optical axis, providing an intensified target image. The sight is focused by direct movement of the image intensifier tube relative to the fixed position of the objective lens. A reticle projector is disposed orthogonal to the optical axis and provides a collimated reticle image, the reticle image providing an aiming point for the weapon. The reticle image is superimposed over the target image, which are reflected into an eyepiece of the sight. The eyepiece has an axis between the optical axis and a sight line passing through a pre-existing sight provided with the weapon. Adjustment of the apparent position of the reticle to compensate for azimuth and elevation is accomplished by moving the reticle projector about crossed cylindrical bearings.

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation of U.S. patent application Ser. No. 10/747,067 filed Dec. 30, 2003, and claims priority to that filing date. BACKGROUND OF THE INVENTION [0002] Mobile devices, such as mobile telephones, personal digital assistants (PDAs), portable (e.g., laptop) computers, and paging devices, have become ubiquitous in the world today. In our fast-paced society, we rely on such devices to give us greater flexibility in our daily lives, for business, family, and pleasure. With the proliferation of mobile network devices has come a proliferation of mobile wireless networks. [0003] Many wireless networks may interface with fixed (wired) networks via access points (APs) that are root units (RUs). The RUs may generally be wired into the fixed networks and may communicate via wireless means with other elements of a wireless network. However, in general, an RU may only be able to be communicate with wireless network elements within its own signaling range. [0004] The signaling range of an RU may be improved via the use of one or more APs that serve as RU range extenders (REs), which may communicate with at least one other AP (RU or other RE) and with other wireless network elements. An RE may act to relay communications between an AP and another wireless network element. A problem with the use of REs, however, is that they may result in a need for networks using them to be manually configured (that is, their topologies may need to be manually determined). BRIEF DESCRIPTION OF THE DRAWINGS [0005] Preferred embodiments of the invention will now be described in connection with the associated drawings, in which: [0006] FIG. 1 depicts a conceptual block diagram of a system implementing an embodiment of the invention; [0007] FIG. 2 depicts a conceptual block diagram of a root range extender (RE) access point (AP) according to an embodiment of the invention; [0008] FIG. 3 depicts a state diagram of a RE according to an embodiment of the invention; [0009] FIG. 4 depicts a flowchart depicting a process according to an embodiment of the invention; [0010] FIG. 5 depicts a conceptual diagram of an information element that may be used in an embodiment of the invention; and [0011] FIG. 6 depicts an exemplary implementation of an embodiment of the invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS [0012] In the following description, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known circuits, structures, and/or techniques have not been shown in detail in order not to obscure an understanding of this description. [0013] References to “one embodiment”, “an embodiment”, “example embodiment”, “various embodiments”, etc., indicate that the embodiment(s) of the invention so described may include a particular feature, structure, or characteristic, but not every embodiment necessarily includes the particular feature, structure, or characteristic. Further, repeated use of the phrase “in one embodiment” does not necessarily refer to the same embodiment, although it may. [0014] In the following description and claims, the terms “connected” and “coupled,” along with their derivatives, may be used. It should be understood that these terms are not intended as synonyms for each other. Rather, in particular embodiments, “connected” may be used to indicate that two or more elements are in direct physical or electrical contact with each other. In contrast, “coupled” may mean that two or more elements are in direct physical or electrical contact with each other or that the two or more elements are not in direct contact but still cooperate or interact with each other. [0015] An algorithm is here, and generally, considered to be a self-consistent sequence of acts or operations leading to a desired result. These include physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. It has proven convenient at times, principally for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers or the like. It should be understood, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. [0016] Unless specifically stated otherwise, as apparent from the following discussions, it is appreciated that throughout the specification discussions utilizing terms such as “processing,” “computing,” “calculating,” “determining,” or the like, refer to the action and/or processes of a computer or computing system, or similar electronic computing device, that manipulate and/or transform data represented as physical, such as electronic, quantities within the computing system's registers and/or memories into other data similarly represented as physical quantities within the computing system's memories, registers or other such information storage, transmission or display devices. [0017] In a similar manner, the term “processor” may refer to any device or portion of a device that processes electronic data from registers and/or memory to transform that electronic data into other electronic data that may be stored in registers and/or memory. A “computing platform” may comprise one or more processors. [0018] Embodiments of the present invention may include apparatuses for performing the operations herein. An apparatus may be specially constructed for the desired purposes, or it may comprise a general purpose device selectively activated or reconfigured by a program stored in the device. [0019] Embodiments of the invention may be implemented in one or a combination of hardware, firmware, and software. Embodiments of the invention may also be implemented as instructions stored on a machine-readable medium, which may be read and executed by a computing platform to perform the operations described herein. A machine-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computer). For example, a machine-readable medium may include read only memory (ROM); random access memory (RAM); magnetic disk storage media; optical storage media; flash memory devices; electrical, optical, acoustical or other form of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.), and others. [0020] FIG. 1 depicts a system in which embodiments of the present invention may be implemented. In FIG. 1 , the system may include an RU 11 , which may, for example, be connected to a fixed network 10 , through which RU 11 may communicate with other fixed stations 12 on fixed network 10 . RU 11 may also communicate with wireless network elements, for example, 13 , 14 , via wireless communications. [0021] The system may include among its wireless network elements REs, e.g., 14 - 16 , and/or wireless stations, e.g., 13 , 17 , 18 . Wireless stations 13 , 17 , 18 may include, but are not limited to, mobile telephones, mobile radios, portable computers, PDAs, paging devices, etc., and they may or may not be mobile. [0022] FIG. 2 shows a conceptual block diagram of a wireless network element (e.g., a wireless station or RE) according to an embodiment of the invention. The wireless network element may include a receiver 22 and a transmitter 23 , as well as control logic 21 . There may be multiple transmitters and/or receivers, as well. Control logic 21 may be implemented in the form of hardware, software, firmware, etc., or combinations thereof. [0023] FIG. 3 depicts a state diagram that may represent the operation of control logic 21 according to an embodiment of the invention. Although this discussion will consider primarily the case of an RE, the state diagram of FIG. 3 may be applicable to either or both of REs and wireless stations, and/or other wireless network elements. The RE (or other network element) may begin in a power down state 30 , in which it is not connected to the wireless network. When the RE powers up, it may first enter an auto detect state 31 . In auto detect state 31 , the RE may detect beacons transmitted from other wireless network elements (e.g., RUs or REs) and may choose a wireless network element corresponding to one of the detected beacons. The chosen beacon may correspond, for example, but is not limited to, a wireless network element that is the fewest number of hops (i.e., point-to-point transmission steps, representing a topological distance) from an RU, a wireless network element whose beacon has the greatest received signal strength, or some combination of these and/or other criteria. When a beacon is chosen, the RE may then associate itself with the corresponding wireless network element and establish a communication link between itself and that wireless network element. This causes the RE to enter the link state 32 . In the link state, the RE may transmit its own beacon and may remain associated with the aforementioned wireless network element (in the case of a wireless station, a beacon may not be transmitted). Should the RE power down during either auto detect state 31 or link state 32 , it may return to power down state 30 . Furthermore, should the wireless network element with which the RE has associated power down, move out of communication range, or otherwise become unavailable, or should the RE be moved, the RE may disassociate from the wireless network element and may re-enter the auto detect state 31 . [0024] The process described in connection with the state diagram of FIG. 3 may be further explained in connection with the flowchart of FIG. 4 . Upon power up, block 41 , the RE may attempt to automatically detect at least one beacon frame, block 42 , transmitted by one or more APs (RUs and/or REs); the beacon frame will be discussed below in further detail in conjunction with FIG. 5 . The auto detection of block 42 may continue for a predetermined period, block 43 . This may, alternatively, continue until at least one beacon frame is detected. [0025] If the predetermined period has expired, block 43 , then the process may continue to block 44 to determine if at least one beacon frame corresponding to at least one AP has been detected. If not, the process may loop back to block 42 to perform further detection. If at least one AP has been detected, the process may continue to block 45 . [0026] In block 45 , the RE may decide among detected APs, as discussed above in connection with FIG. 3 , based on such factors as number of hops, received signal strength, and combinations of these and/or other factors (but not limited thereto). As will be discussed below, the beacon frames may include information regarding number of hops. Upon deciding among the detected APs, the RE may then establish a communication link with the AP decided upon (the “chosen AP”). [0027] In the case of a wireless station, the process of auto detection and configuration may be considered to be complete. In this case, as will be discussed in greater detail below in connection with an RE, the wireless station may remain associated with the chosen AP for as long as it continues to detect beacon frames. If no beacon frame is detected from the chosen AP for more than some predetermined time period, the wireless station may then disassociate itself from the chosen AP and may go back to block 42 and commence auto detection. [0028] In the case of an RE, on the other hand, the process may continue with block 46 . In block 46 , the RE may begin transmitting its own beacon frame. In such a case, the RE may increment the number of hops in its own transmitted beacon frame, in comparison with the beacon frame received from the chosen AP. That is, if the chosen AP was n hops from an RU, the RE may transmit a beacon that indicates it is n+1 hops from an RU. [0029] The RE may also form communication links with other wireless network elements (e.g., other REs and/or wireless stations) that may detect the RE and may seek to establish links with the RE as their AP. [0030] Additionally, the RE may start an AP beacon timer. The chosen AP may continue to transmit its beacon frame, and the RE may continue to detect it. By so doing, the RE may ensure that the chosen AP is still available and that its communication link with the AP may continue to be maintained. The AP beacon timer may provide a “time-out” period during which, if a beacon frame is not received from the chosen AP, the RE may determine that the chosen AP has become unavailable, block 47 . On the other hand, whenever a beacon frame is received from the chosen AP, the AP beacon timer may be reset, and a new period may begin. [0031] If the AP beacon timer times out, block 47 , the process may continue to block 48 . In block 48 , the RE may cease transmitting its beacon frame, e.g., to reflect the fact that it may no longer be an AP for the network. Accordingly, the RE may de-authenticate any wireless network elements that have established connections to the RE as an AP. The process may then loop back to block 42 , and the RE may then re-commence auto detection. [0032] As discussed above, embodiments of the invention may utilize a beacon frame containing certain information. An exemplary implementation of such a beacon frame is shown in FIG. 5 . A beacon frame 51 may contain various control and address fields, for example, as well as a payload 52 . Payload 52 may contain various fields, which may include, but which are not limited to, a time stamp, a beacon interval, a capability field, etc. In embodiments of the invention, in particular, payload 52 may comprise an information element (IE) 53 tailored to carry information useful in the above-described auto detect/auto configure process. In one particular implementation, IE 53 may comprise a unique identifier 55 , a length field 56 , which may contain a length of payload 52 , and a network information field 57 . Network information field 57 may include, but is not limited to, a distance, in terms of a number of hops from, an RU to a wireless network element transmitting the beacon frame. For example, an RU may transmit a beacon frame including a distance of zero, an RE connected to that RU may transmit a beacon frame containing a distance of one, and so on. [0033] Some embodiments of the invention, as discussed above, may be embodied in the form of software instructions on a machine-readable medium. Such an embodiment is illustrated in FIG. 6 . The computer system of FIG. 6 may include at least one processor 62 , with associated system memory 61 , which may store, for example, operating system software and the like. The system may further include additional memory 63 , which may, for example, include software instructions to perform various applications. System memory 61 and additional memory 63 may be implemented as separate memory devices, they may be integrated into a single memory device, or they may be implemented as some combination of separate and integrated memory devices. The system may also include one or more input/output (I/O) devices 64 , for example (but not limited to), keyboard, mouse, trackball, printer, display, network connection, etc. The present invention may be embodied as software instructions that may be stored in system memory 61 or in additional memory 63 . Such software instructions may also be stored in removable media (for example (but not limited to), compact disks, floppy disks, etc.), which may be read through an I/O device 64 (for example, but not limited to, a floppy disk drive). Furthermore, the software instructions may also be transmitted to the computer system via an I/O device 64 , for example, a network connection; in this case, the signal containing the software instructions may be considered to be a machine-readable medium. [0034] The invention has been described in detail with respect to various embodiments, and it will now be apparent from the foregoing to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects. The invention, therefore, as defined in the appended claims, is intended to cover all such changes and modifications as fall within the true spirit of the invention.

Automatic detection of access points and range extension points and automatic configuration may be used to eliminate a need for manual configuration.

CROSS REFERENCE TO RELATED APPLICATION This application is a continuation of application Ser. No. 481,010, filed Mar. 31, 1983, now abandoned. FIELD OF THE INVENTION The subject matter of the present invention pertains to improvements in logic state analysis, and may apply to both logic state analyzers and the debuggers used in conjunction with emulators. BACKGROUND AND SUMMARY OF THE INVENTION The development of executable code for processor based systems frequently involves the use of compilers and assemblers that produce relocatable object code. When such programs are subsequently linked and loaded a trace listing provided by a logic state analyzer can be at best tedious to appreciate, and at worst extremely difficult to follow. Even a reverse assembler can not replace a reference to an arbitrary address with the corresponding symbol used in the original source program. To do that requires an appreciation on the part of the user of how the various software tools interact, and of how they modify the relocatable object code to produce a final absolute value. A considerable amount of tedious nondecimal arithmetic may be required to relate the actual events reflected in the trace to a collection of source program listings. The situation would be bad enough in cases where the hardware in the target system is known to be good, and what is being debugged is simply the software. But in many development situations there may be bugs in both the hardware and the software. This makes it especially important to be able to rely on the trace for information about what really happened, as there may well be a discrepancy between actual events and the legitmate aims of even a properly written program. Under these circumstances it would be less wise to think of the trace as a hardware version of the program listing, and more useful to think of the program listing as a guide to understanding the trace. In these types of situations the extra overhead of "unrelocating" a trace can be particularly burdensome. It would be especially desirable if all absolute values for addresses and operands in the trace were replaced with notations involving the symbols used by the programmer in the original source programs. Such symbols might refer to individual locations or to ranges of locations. It would be useful if similar symbols could be defined in addition to the ones found in the source listings, without having to edit the sources to include them. It would also be helpful if references to original source program line numbers could be included in the trace, or even actual source lines. This would aid a great deal in allowing the user to follow overall program flow. Another development or troubleshooting situation pertinent to the invention can arise in connection with the operation of finite state machines. A trace of such a state machine is a sequential series of states: e.g., 001001, 010001, 010011, etc. It is frequently the case these states can be given labels, such as "INC -- P -- REG", (increment P register), "WAIT -- MEMC", (wait for Memory Complete), or STM (Start Memory Cycle). It would be desirable if a logic analyzer could provide a listing of the trace in terms of such labeled states. Each state in the listing would either be a label or a value relative to a label. In the latter case there might be several states in some process, say a read memory cycle. The label RMCY might refer to the first state in the process. RMCY+3 would denote the fourth state therein without having to invent labels for every separate state in the process (and by implication, in the entire machine). The ability of the logic state analyzer described herein to integrate source program symbols and source lines into the trace listing arises from giving that analyzer access to the symbol tables produced by any compiler or assembler that produced the code (whether absolute or relocatable) and by giving the analyzer access to the decisions made by the linker or relocating loader. Using this information the analyzer can determine by various inspection processes what symbols to use in the trace listing. A further benefit emerges from the ability to do this. It is then also possible to at once expand and simplify the process of defining the trace specification for the analyzer. The trace specification tells the analyzer under what conditions to commence the trace and exactly what type of information to include therein. With the aid of the invention it is possible to use source program symbols in the trace specification without having to learn what their absolute values are at run time. This is quite useful, as those absolute values are apt to change as bugs are found and fixed, or as different versions of the software are developed and tested. But an analyzer constructed to take advantage of the various symbol tables and the load map need not have its trace specification altered merely because one or more programs are of different lengths than before, or because the programs are loaded in a different order. The symbolic nature of a "relocatable trace specification" makes that unnecessary. These principles may be extended to apply to logic state analysis performed upon target systems that incorporate memory management units. In such target systems the relocated addresses issued by the processor are virtual addresses that are further modified in real time by the memory management unit as the processor runs. The modified addresses are the actual physical addresses sent to the memory. Their values are contingent upon run time conditions reflecting what parts of memory are allocated to which programs or tasks. These allocations are dynamic, and generally cannot be given in advance as fixed absolute offsets to be applied to the relocated addresses present at run time. Those relocated address are themselves offset by some relocation base from the relocatable addresses issued by the assembler or compiler, as mentioned above. Thus, such a memory managed address involves some absolute value that results from dynamically offsetting a relocated value that is already offset by a fixed amount from the relocatable value appearing in the source listings. The dynamic offsets mentioned above need not be entirely private to processes within the target system, and therefore mysterious to the logic state analyzer. The symbols representing the various dynamic offsets can be defined to the logic state analyzer. Then provided certain criteria pertaining to keeping public knowledge of the offsets current (a task specific to the nature of the target system) a logic analyzer constructed in accordance with a preferred embodiment to be described can continuously adjust during run time the "real" absolute trace specification to match the symbolic one entered by the user. In like fashion it also can properly insert source symbols into the trace listing, even though the trace pertains to a program whose position in memory was determined dynamically at run time. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an idealized schematic representation of the relationship between certain programs executed as a workpiece to illustate the various operational features of the invention. FIG. 2 is a simplified block diagram of a Logic State Analysis System capable of incorporating the principles of the invention. FIG. 3 is a diagram illustrating the relationship between various file names resulting from the application of the Analysis System of FIG. 2 to the workpiece programs of FIG. 1. FIG. 4 is a diagram relating certain kinds of information about symbols defined either by the user during debugging or in the programs being traced to various Trace, Format and Map Specifications on the one hand and an unrelocated Trace List on the other. FIG. 5 is a flow chart describing the relationship in FIG. 4 between the Symbol Maps and the Trace Specification. FIG. 6 is a flow chart describing the relationship in FIG. 4 between absolute values associated with the Trace List and the various Trace Symbols. DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 is a block diagram of the functional relationship between certain component portions of a simple computer program 1 constructed as a workpiece to illustrate the various operational aspects of the invention. The compilation and execution of the program of FIG. 1 provides an example environment within which the operation and utility of the invention is explained. Appendices A through U pertain to that explanation. Following that, the internal operation of the invention is discussed in connection with FIGS. 2 through 6. Turning now to the workpiece program 1 of FIG. 1, a main program 2 and an associated subprogram 3 cooperate with a data structure 4 named "DATA -- BLOCK". Both the main program 2 and the subprogram 3 are written in PASCAL, although any of a number of other programming language might have been used, as well. The name of the main program is "MAIN", while the name of the subprogram 3 is "FACTOR". Associated with these two Pascal programs and their data structure are three utility programs from the run-time library invoked by the PASCAL complier during compilation of the programs MAIN and FACTOR. These are a parameter passing routine 5 named PARAMETER, a multiplication routine 6 named MULTIPLY, and a routine 7 named BOOLEANIN that checks if a specified bit in a specified word is set. BOOLEANIN finds use, for example, in the evaluation of PASCAL "IF" statements. Each of these program elements will now be briefly considered in turn. Turning now to page i of Appendix A, shown there is the PASCAL source listing of the program MAIN 2. What the program MAIN does is fill the data structure DATA -- BLOCK with the factorials of the consecutive integers zero through twenty. To do this if references an external integer array conveniently named DATA -- BLOCK. The index into the array is named INDEX, and an external function FACTORIAL returns the value n! for a supplied integer n. A simple FOR loop assigns the factorial of the value of the index to the location identified by the index. This is done for pointer values of from zero to twenty. The source listing in PASCAL of the function subprogram FACTOR is shown on page i Appendix B. We shall not dwell upon what a factorial is, or upon the logical arrangement of the subprogram FACTOR 3. Programs MAIN 2 and FACTOR 3 are presented merely as portions of a workpiece in an example situation. The situation involves either verification or troubleshooting of the operation of FACTOR. More specifically, the example will involve tracing the operation of the function FACTORIAL upon a supplied value of three. We will find that this will involve such things as passing the parameter NUMBER to the function FACTORIAL (using PARAMETER), using BOOLEANIN to accomplish a portion of the IF statement on line ten, and the use of MULTIPLY in line twelve. We mention these things because it is by examining the associated portions of a trace produced by a logic state analyzer constructed in accordance with the invention that exactly what happens during such key portions of FACTORIAL can be observed. In short, the idea is to observe the input, the output and some of the important points inbetween. To briefly look ahead for a moment, why this is conventionally easier said than done will be the subject of Appendix L, and why with the aid of the invention it is as easily done as said the subject of the remaining Appendices. But for now, we must continue with the placement of our example workpiece program into the environment of an actual system so that tangible actual results can be explained and compared. To continue then, page i of Appendix C is a commented assembly language program DATA -- BLOCK that satisfies the "external" referenced in MAIN, and provides for the storage requirements of the integer array. The operative portion of DATA -- BLOCK is line twenty-one. There a "BSS 21" instruction reserves twenty-one words, the first of which is associated with the symbol DATA -- BLOCK. Those familiar with assemblers will recognize that the "program" DATA -- BLOCK is a program in the sense that it is a text file that may be assembled, even though it does not generate any executable code. What it does do that is of interest in the present example is create a symbol table of all the assembly language labels in the program. One of those (in fact, the only one) is DATA -- BLOCK. That is of future interest. A collateral point of interest is that the "BSS 21" instruction nonetheless increments a program size value that later has the effect of reserving those twenty-one words by the simple expedient of making DATA -- BLOCK appear to be twenty-one words long, even though those words don't contain any code generated by the assembler. To run the workpiece program 1 programs MAIN 2 and FACTOR 3 must be compiled by an appropriate PASCAL compiler and DATA -- BLOCK 4 must be assembled by an appropriate assembler (i.e., ones for the machine language of the processor in the target system that is to execute the workpiece program). Then the whole works must be relocated and loaded. The workpiece program can then be executed. During that execution a logic state analyzer can respond to the occurrence of certain predefined conditions (defined with a trace specification) to selectively trace all or only selected events (we will select all events). A format specification matches the logical constructs of "address", "data", and "status" to particular groupings of the electrical signals monitored by the logic state analyzer. The resulting trace is a record of system activity in the vicinity of conditions defined in the trace specification. In the traces that appear in the various appendices to follow the "trigger event" is the third item in the trace, so that the bulk of the trace shows what happened subsequent to the triggering event. But first, the programs MAIN 2 and FACTOR 3 must be compiled and loaded. Appendix C has already shown the result of assembling DATA -- BLOCK 4. With this in mind, consider the expanded compiler listings of Appendices D and E produced by compiling the programs MAIN 2 and FACTOR 3. Our ultimate goal for the example under construction is to obtain a trace for the following trace specification (which we render here in plain English): "Get ready to start the trace when INDEX is assigned the integer value three and then trigger the trace when the address equals FACTORIAL and status equals opcode (i.e., the first instruction in the object code for FACTORIAL is being fetched for execution)." To put such a trace specification into effect one must not only translate the desired meaning into an appropriate collection of switch settings and keystrokes, etc., according to the syntactical idiosyncracies of the particular logic state analyzer at hand, but one must also supply particular (i.e., absolute) addresses and values for such things as FACTORIAL and INDEX. And should FACTOR invoke any other routines, then the user must ordinarily be prepared to translate addresses in those portions of the trace into meaningful locations in those invoked routines. To do this he would use a load map provided by the linker or relocating loader to learn which routine any such address fell within, and then study the compiler listing for that routine to follow what activity is represented by the trace. In connection with these activities it will be noted that several types of items of interest appear in the listings of Appendices D and E. At the far left side of each listing and in a column labeled "location" is the relocatable address for each word of code emitted by the compiler. In a column labeled "source line" appears the line number in the original PASCAL source listing that caused the associated machine instructions. That line of source is listed, with resulting machines code shown below it. Note that symbols defined by the user in his source programming, such as INDEX at line twenty-six of page i of Appendix D (which relates to line eighteen of the PASCAL source listing of MAIN), results in code that uses the symbol INDEX. But that use of INDEX now needs an implementing definition in the context of an executable machine language program. This is done at line forty-two of page i of Appendix D, with a "BSS 1" whose hexadecimal relocatable address is 0010H. To carry out the planned example using a conventional logic state analyzer one must replace INDEX with the final relocated value for 0010H assigned to the compiled code for MAIN. And that is just one instance of such correspondence out of several. A similar thing needs to be done to actually specify in a conventional trace specification what is the absolute address of the first instruction executed in FACTOR. As if this were not bad enough, it can easily get worse; and in our example, it does. Recall the utility programs PARAMETER 5, MULTIPLY 6 and BOOLEANIN 7. The compiler produces code that uses those routines; see the JSM instructions at lines fourteen, twenty-two and thirty-eight on page i of Appendix E. The trace that is produced in our example includes such JSM's and their associated activity. This is not unreasonable, in that if something were wrong it might be necessary to delve into the operation of these or other utility routines to understand the nature of the failure. Now in some installations the utilities in the run time library might only be just so much relocatable machine code programs whose real meanings remain forever a mystery. A more civilized approach is for the run time library to contain not only the relocatable code for each utility, but also either the source itself or a text file containing the expanded compilation. If this latter were available it would make the task of following each step through a complete trace at least no more difficult than it would be if there were no such library utilities invoked by the compiler. That is to say, it becomes doable, but not necessarily easy. Appendices F, G and H are the assembler listings for the three utility routines PARAMETER 5, MULTIPLY 6 and BOOLEANIN 7, respectively. The details of how those programs operate are not terribly pertinent to an understanding of the import of our example, and will be left to an investigation by the interested reader. Appendix I is a load map indicating where, for the particular example under consideration, each of the user programs MAIN through DATA -- BLOCK and the library programs BOOLEANIN through MULTIPLY was loaded for execution. The column labeled "PROGRAM" contains the hexadecimal values at which each block of code begins. Traditionally, a load map such as the one of Appendix I is a virtual necessity when tracing program flow described with relocatable listings, as the following examples pertaining to Appendices J, K and L show. Appendix J is a format specification that tells the logic analyzer which electrical lines (i.e., which probes for each of the various probe pods) are address lines, which are data lines, and which are status lines, etc. In the present example these collections are also labeled "Address", "Data" and "Status", respectively. The term used herein to refer to such symbols as "Address" pertaining to the address collection of signals is the noun "data label." As will be described shortly data labels such as "Status" have associated therewith pluralities of values; there is more than one status. (These various values can be represented symbolically also, and may be arranged into symbol maps.) The format specification also identifies the electrical logic polarities and threshold levels the signals are expected to obey. Appendix K is a trace specification defining the nature of the information to be recorded by the logic state analyzer while it monitors the execution of the workpiece program. We shall turn to just what that is and why it is of interest in a moment. Both Appendices J and K pertain to a logic state analyzer such as Hewlett-Packard Company's 64620S Logic State/Software Analyzer for use with the HP 64000 Logic Development System. The target system which the trace is for is one that includes a "BPC" (Binary Processor Chip) as the microprocessor. And although it is not particularly necessary to study the properties of the BPC to appreciate the example under construction, those interested or wishing a description of its instruction set, bus structure and internal architecture may find these described in considerable detail in U.S. Pat. No. 4,180,854. See col's 152 through approximately 200, FIGS. 44 through 132Cc. To return now to the example under construction, the high level description of what the trace specification of Appendix K means is "Get ready to start the trace when INDEX is assigned the integer value three and then trigger the trace when the address equals FACTORIAL and status equals opcode." To create a trace specification with such a meaning one must not only follow the proper syntactical conventions such as "enable -- after" and "on Address", but one must also correctly supply certain definite values: "enable -- after Address=???" That is, the user has to come up with the "8012H" in line two of Appendix K. In this particular example the "8012H" is found by noticing that MAIN is loaded beginning at 8002H and that INDEX is at 10H (relocatable) in MAIN: 8002H plus 10H equals 8012H. And while this is not a formidable task in itself, such arithmetic may be needed in numerous places when interpreting the trace, so that following the flow of the program listing through the trace is rather like being nibbled to death by mice. Nor would it necessarily do any good to commit 8002H to memory and learn to add and substract by sight in hexadecimal. For as soon as any changes are made to the programs (which might happen many times during the course of a major project) there would appear new relocatable addresses which would likely be relative to entirely different relocation bases. That then, is the general situation pertaining to Appendix L, which is an abbreviated rendition of the trace obtained in accordance with Appendices J and K for the programs of Appendices A through H and the load map of Appendix I. Let us now briefly consider a portion of Appendix L. Notice that at line "trigger" on page i of Appendix L there occurs "08013 LDA 8030". According to the load map of Appendix I address 8013H is the start of the program FACTOR. At line +004 there is a "JSM 806D", followed by a change of address to 806DH at line +006. Looking only at the trace of Appendix L does not answer the question "What is 806DH?" If this JSM were of interest, what would one do to answer that question is to first notice by an inspection of the load map (Appendix I) that 806DH falls between 8069H and 808FH, so that the absolute address 806DH refers to something in PARAMETER. The load base for PARAMETER is 8069H. The referenced location minus the load base is 0004H, which is a relocatable location in PARAMETER. Now by looking at line forty-nine in the assembler listing for PARAMETER (page ii of Appendix F), notice that (relocatable) location 0004H is assigned the label PARAMETER -- ENTRY. Therefore, "JSM 806D" is really "JSM PARAMETER -- ENTRY." Similar analyses apply to other address changes (JMP's, JSM's, etc.) and any associated RET's. Various such instances can be located in Appendix L, although for the sake of brevity we shall content ourselves with the one given concerning 806DH. We shall have occasion to use that instance again to illustrate the utility of the invention. It is to that illustration which we now turn our attention. An additional "map specification" supplied to the logic state analyzer by the user, done at generally the same time as the user supplies the format and trace specifications, allows the analyzer to perform the relocation needed for symbolic trace specification, as well as the "un-relocation" needed for creation of the symbolic trace listing. Appendix M contains such a map specification having two symbol maps, each of which relates various symbols to a single value or range of values. A single value may be uniquely specified in any base, or may also be non-uniquely specified in any base by the inclusion of "don't care" characters. These values are absolute, and are obtained either from a load map or from abolute listings. In the general case the map specification may contain a collection of one or more such symbol maps. The reason that more than one symbol map may be needed is that the symbols generally represent logically disjoint phenomenea such as "address" and "status." For example, in the case of the BPC microprocessor mentioned earlier, an address of zero represents the A register while a status of zero (for a given choice of how to group certain control lines) represents a memory write cycle. It is this possibility of separate and independent meanings for the same value that requires partitioning of the various types of symbols into separate collections. These collections generally reflect the functional division of labor exhibited by the various signals going to and from the processor. However, it is not absolutely necessary that the actual electrical signals themselves be disjoint; what is required is logical independence. In the BPC, for example, the address and data lines are one and the same, but the different types of information occur at different times. A property called "clock qualification" (which is explained in U.S. Pat. No. 4,338,677, issued to Morrill on July 6, 1982) provides the ability for a logic state analyzer to demultiplex logically separate but electrically common entitles in such situations. Referring specifically now to Appendix M, at line six the symbol FACTORIAL is defined as the single unique absolute value 8013H. At line seven the symbol Z is defined as the range of absolute values 22H through 0C2H. Any value falling within that range will appear in the trace listing as a value relative to some reference location which itself may or may not actually be within the range. (The reference locations which usually have the greatest utility are the start of the range, the end of the range, and zero. But other values are at least conceivable, and such values are allowed and implemented.) Values within Z, for instance, will appear in the trace listing as the symbol Z plus or minus an offset, where the offset is relative to 42H. This feature is useful in instances where the symbol represents a compiler heap or perhaps an array, neither or whose indices are zero. At line eight of Appendix M the symbol MAIN is defined as the absolute range 8002H through 8012H, relative to the start of the range. At line fourteen the symbol STACK is defined as the absolute range 0F9F0H through 0FA17H, relative to the end of the range. And finally, at line 31 the symbol Error is defined as the nonunique value 1XXXB. Any value in the range 1000 binary to 1111 binary will appear in the trace listing as simply the symbol Error. In a preferred embodiment the map specification may be entered in either of two ways. In the first way the user gathers the relevant information provided by various software tools (assemblers, compilers, linkers, etc., some of which may run on disparate equipment in various locations other than the target system) and then constructs a table of information corresponding to the desired map specification. He then keys this information into the logic analyzer. For example, in a microprocessor controlled logic analyzer, such as the HP 64620S, he may use a series of keystrokes similar to the ones of the entry example shown in Appendix M. These amount to syntaxes for manual entry of the map specification. A second way of entering the map specification involves the user's preparation of a properly formatted table or tables of information within a file on some mass storage medium. The map specification may then be communicated to the analyzer by mounting that disc or tape into a drive therein and instructing the analyzer by a suitable syntax to read that file to obtain the map specification. Alternatively, the file could be transmitted over a suitable data link, such as RS-232 or IEEE 488. In conjunction with the addition of a map specification, an alteration to the associated format specification is desirable. The changed format specification is shown in Appendix N, which differs somewhat from the earlier form specification found in Appendix J. The differences appear at lines fifteen, twenty-six, and thirty-seven. The import of line fifteen is that a default symbol map for the data label Address is a symbol map named Address -- symbols. There might be other appropriate symbol maps with other names, and one of those could be specified in place of Address -- symbols if that were desirable. The same general situation exists for the status map. At line thirty-seven the associated default map is identified to be one named Stat -- map. There might well exist different status maps having different names. And at line twenty-six the existence of a default data map is denied. Absence of any such map means that data values are represented in the trace listing simply as their absolute values. (In the present example the base for such absolute values defaults to hexadecimal in the absence of any specification to the contrary.) Finally, note that these default map definitions in the format specification merely select which symbol maps to use if the default situation is actually achieved. Some particular symbol maps may be specified ("somewhere else"), in which case the default condition does not obtain. That "somewhere else" is in a trace specification, which is also now somewhat different than it was, as, say, in Appendix K. Turning now to Appendix O, the modified trace specification is shown; it uses symbols to accomplish the same measurement as specified in Appendix K. It mentions no symbol maps, however, so the default choices of Appendix N are invoked. Also shown in Appendix O is another (entirely separate) sample trace specification that would produce an entirely separate measurement. It is included because it does mention a symbol map, which overrides the default choice specified for the given data label in the format specification. The point is that the actual invoking of a symbol map specification (whether explicitly or by default) occurs in the modified trace specification. Now compare the resulting (but abbreviated) trace list appearing in Appendix P, pages i and ii, with the conventional trace list appearing in Appendix L. In particular, compare line +004 of Appendix L with line +004 of Appendix P. While in the former the disassembled instruction was rendered "JSM 806D", in the latter it appears as "JSM PARAMETER+0004." The "PARAMTER+0004" represents the relocatable location in the file named PARAMETER corresponding to the symbol "PARAMETER ENTRY" that appears in the source program for the parameter passing routine 5. In this case the map specification of Appendix M does not include the symbol PARAMETER -- ENTRY, so all references to values within the range 8069H through 808EH are "demapped" to values relative to the start of that range. Both the absolute value 806DH and the symbol PARAMETER -- ENTRY are the fourth location the that range. Refer again to the map specification of Appendix M. Notice that the symbol FACTORIAL is defined as the absolute value 8013H, and that the symbol FACTOR is defined as the range 8013H through 8038H. Observe that FACTORIAL is thus a value within FACTOR. Now observe the "trigger" line on page i of Appendix P. The particular value defined as FACTORIAL is rendered as FACTORIAL rather than as a value relative to the start of the range FACTOR, as occurs in, say, lines +001 through +005. Notice also on page i of Appendix P that at lines +066 and +077 occur demapped references to the range Z that lie on opposite sides of the reference location 42H. Line +075 illustrates a reference to STACK demapped relative to the end of its defined range of OF9OFH through OFA17H. Now compare lines "trigger" through +005, +066, +075 and +077 of Appendix P to those same lines in Appendix L. It is abundantly clear that the trace listing of Appendix P is considerably easier to use. Notice further that a casual perusal of the conventional trace listing of Appendix L gives no sense of overall program flow; the instructions themselves have been disassembled, but the operands and address remain just so many numbers whose connection to the symbols of the source programming is obscure. The trace listing of Appendix P is in distinct contrast in that it is obvious that from lines +065 through +074 that the trace concerns program execution in the utility program BOOLEANIN 7, after which program execution transfers to a range labeled FACTOR, whose limits are known to correspond to the extent of the executable code for to the user written subprogram FACTOR 3. The improved trace listing of Appendix P is possible, in part, through the agency of the map specification in Appendix M. However, that particular map specification, while providing a definite improvement, still required a modest amount of additional effort on the part of the user. That is, he still had to key in the names of the various symbols and their values. That is in contrast with the circumstances surrounding Appendix Q. Referring again briefly to Appendix I, notice that one of the pieces of information concerning the listing output from the linker (i.e., the "load map") appears in line eighteen as "absolute & link -- com file name=WORKPIECE:EXAMPL". What this means is that a related file specified as "WORKPIECE:EXAMPL:link -- sym" includes, among other things, "range records" of named "user segments" and their associated start and end locations in memory. The names of the user segments are the same as the file names of the various program segments to be linked and loaded. Returning now to Appendix Q, consider a command such as: " . . . define link.sub.-- sym film WORKPIECE:EXAMPL . . . " This command would be issued by the user as part of the map specification and in lieu of keying in the names of the symbols and their ranges. The " . . . define . . . " command itself is not shown as part of Appendix Q; what is shown is the result of issuing that command. That result is the "linked -- files" information of lines twenty-five through thirty-four of Appendix Q. This makes some extra information part of the map specification compared to what was available in Appendix M. The extra information is that both start and end values for the range of a symbol are provided. By this means it will later be possible in the trace listing to indicate that an address or operand is outside any such range by the simple expedient of rendering it is an absolute value, while those that are within such a range are rendered as either a specific unique symbol or as relative to the particular symbol associated with that range. Before examining the resulting trace list for this newest example, a somewhat different trace specification must also be considered. The user, at this point, would think of the trace specification in terms of the symbols INDEX and FACTORIAL. But the new map specification of Appendix Q does not explicitly show those symbols, although the information is implicity present. That is, the symbol INDEX is declared to be global in the file named MAIN:EXAMPL (see line forty-four of Appendix D) and the symbol FACTORIAL is declared to be a global function in the file named FACTOR:EXAMPL (see line fifty-five Appendix E). This implicit connection is made explicit by associating in the trace specification the file name MAIN:EXAMPL with the symbol INDEX and the file name FACTOR:EXAMPL with the symbol FACTORIAL. See lines two and four of Appendix R. Now consider the resulting trace list, shown in pages i and ii of Appendix S. First, observe the by now familiar example of line +004. That line of the trace is now rendered as: "FACTOR+00002 JSM PARAMETER -- ENTRY, PARAMETER . . . ." The difference between line +004 of Appendix S and line +004 of Appendix P is that the operand of the JSM instruction is now rendered as PARAMETER -- ENTRY rather than as merely PARAMETER+0004. This is based on inspection of a file produced upon the assembly of PARAMETER:EXAMPL. (The actual complete specification of that file is PARAMETER:EXAMPL:asmb -- sym. This reflects a "file name:user id:file type" convention employed by the Operating System used to manage files and run the compiler, assembler and linker, etc.) The ",PARAMETER" following the operand of the JSM refers to the complete file specification; it identifies the file used to produce the symbolic rendition of the JSM's operand. But since the display may be limited to eighty columns, and since the user can be expected to appreciate any such "name:user id:type" conventions, supplying only the name portion is a generally adequate compromise. In a trace list such as in Appendices P and S the "direction of look up" is from the absolute value in hand (that came from the state analyzer) to the symbol (found in some file used by the linker). Owing to the more comprehensive nature of the information in the file WORKPIECE:EXAMPL that was incorporated into the map specification for the trace list of Appendix S, look up operations to find the absolute value of a symbol can be performed for all addresses and operands. See for example, line +006 in Appendix S. It is rendered as: " . . . PARAMETER.sub.-- ENTRY, STA DOPEVECTOR, PARAMETER . . . " rather than as merely: " . . . PARAMETER+00004 STA PARAMETER+0000 . . . ". Once the ability to inspect source files for symbol names is at hand, as described in connection with Appendix S, it is also possible to include in the trace listing those original source program line numbers that produced the run time activity captured by the trace. In Appendix T, for example, we see that lines "trigger" through +004 are associated with line #8 of the source program. Such associations are limited to source lines that were compiled; assembled source lines are already in general one-to-one correspondence with the trace listing, owing to their word-by-word or byte-by-byte nature and the similarity of that nature to the executable object code. Appendix T is the same trace listing as before with the addition of such source line numbers. For example, at line -002 of Appendix T we see the notation: " . . . #18 MAIN00.sub.-- L2,MAIN JSM . . . " What this means is that at line eighteen of some source programming in a file named MAIN the compiler generated a label MAIN00 -- L2 and emitted an executable instruction JSM, etc. The next executable instruction came from a source in a file named FACTOR, and so on. Now consider Appendix U. Therein is a complete trace listing for the trace specification of the example used throughout this discussion. Not only are the line numbers included, but one copy of each associated source line is also included at the start of each block of different source line numbers. Referring now to FIG. 2, shown there is a simplified block diagram of an environment within which the invention may be practiced. That environment may include either or both a Logic State Analyzer and an Emulator. As shown in FIG. 2 a Logic State Analyzer Module 8 and an Emulator Module 9 are installed into, cooperate with and are supported by a Host System 10. For example, the Host System 10 could be an HP 64000, the Logic State Analyzer Module 8 an HP 64620S, and the Emulator Mode 9 any of various HP 642XX used in conjunction with an HP 64304 Emulation Bus Preprocessor. The Emulation Bus Preprocessor corresponds generally to switching elements 13 and 14. As shown in FIG. 2 the Logic State Analyzer Module 8 can receive data either from Probe Pods 11 and 12 connected to a Target System 13 under test or from the Emulator Module 9. The invention operates upon the data received by the Logic State Analyzer Module 8 in either case. To facilitate this the Logic State Analyzer Module 8 incorporates switching or multiplexing elements 13 and 14. In a preferred embodiment the Host System 10 controls the operation of both the Emulator Module 9 (if it is present) and the Logic State Analyzer Module 8. To this end an Operating System including various suitable commands is encoded in a System Rom 15 and executed by a Microprocessor 17. This control would involve interaction with the user through a Keyboard 18 and a Display 19, and may involve such notions as "soft keys," "soft front panels," "directed syntax," etc. If a mass storage device 20 is present then command files to establish certain commonly used set-ups may be saved in labeled command files to be recalled and invoked at will. Likewise, the results of various measurements can be stored for later analysis and comparison. The control of the Emulator and Logic Analyzer Modules 9 and 8 involves the preparation of a variety of tables of information, some of which are retained in an area of System RAM 16 and some of which are in distributed addressable locations in the Modules 8 and 9. These distributed locations are responsive to memory cycles upon a Microprocessor Address/Data Bus 21 initiated by the Microprocessor 17. By this means a Trigger Recognizer 23 and a Storage Recognizer 24 can be individually and selectively programmed by the user to accomplish their appropriate recognition tasks for a given measurement. Those tasks ultimately result in state data upon Target State Bus 26 being stored in a Trace Memory 25. This is the raw data of a trace listing that is to be formatted as described in any of Appendices P, S, T and V. Such formatting is in part, accomplished in the preferred embodiment of FIG. 2 by various routines executed by the Operating System encoded in the System ROM 15 of the Host System 10. This involves inspection of various tables and files of information which may be variously found either in the System RAM 16 and the Mass Memory 20. Much of this needed information is generated, as previously described, by the user as he applies the various software tools to compile, assemble link and load the various programs and data structures that become the object of the trace listing. We now turn to just what that information is and how it is used to produce trace listings of the sort depicted in Appendices P, S, T and U. FIG. 3 is a schematic arrangement of various files of interest that are created in the course of generating, loading and executing the workpiece example program of FIG. 1. The Appendix section associated with certain of these files is also indicated. In view of all of the various explanations offered to this point it is believed that an extended explanation of FIG. 3 is not needed and that the Figure speaks for itself. It is a useful diagram, however, as it clearly sets forth the relationships between a multitude of files in which we are interested. FIG. 4 is a schematic arrangement of particular types of data that are of interest in the creation of the unrelocated listings of Appendices P, S, T and U, as well as the application of the associated trace, format and map specifications. Specifically the Captured Data 27 is what the Logic State Analyzer Module 8 would store in the Trace Memory 25. That is the raw information that is to be operated upon to make it as useful to and as easily interpreted by the user as possible. That, in turn, is accomplished by properly interpreting certain Trace Symbols 32 which may be classed as either Software Symbols 28 or Analysis Symbols 29. The Software Symbols 28 are simply those symbols appearing in the various source programs, and that are "passed through" by compilation and assembly. Analysis Symbols 29 are those symbols someone operating the Logic State Analyzer Module will need to bring to the problem, over and above what is already defined in the programming. Examples are the Data Labels that are associated with particular target system signal lines of interest and that can experience various values. For example, three lines might be called Status, and might have various absolute values meaning read, write, instruction fetch, etc. The various Data Labels may be associated with maps wherein the different values are given symbolic names. In addition, the person conducting the analysis can include definitions of symbols of interest solely for the analysis of the particular programming whose execution is being traced, and that would have to be added to the source if they could not be added to the symbol maps. Adding them to the symbol maps saves having to edit, recompile, reassemble, and reload. The Data Labels 30 are defined through the Format Specification 34, while the Symbol Maps 31 are defined through the Map Specification 33. Once those two specifications are made any symbol that is either a Software Symbol 28 or an Analysis Symbol 29 can be used in the Trace Specification 35, and may subsequently appear in the unrelocated Trace List 36. Hence, the union of the Software Symbols 28 and the Analysis Symbols 29 is referred to as Trace Symbols 32. FIG. 5 is a flow chart of a process for replacing a Software Symbol 28 in a Trace Specification 35 with the corresponding absolute address. The flow chart is believed to be self-explanatory. Of course, Analysis Symbols 29 can be also be included in a Trace Specification 35, but their absolute values are obtained from inspection of an associated Symbol Map 31. A flow chart for that has been omitted. FIG. 6 is a flow chart of a process for removing an absolute value in a conventional trace list produced by a logic state analyzer and replacing that absolute value with a symbol in accordance with the various Trace Symbols of FIG. 4. The flow chart shows how and where to look for the various types of symbols that may be defined, as is believed to speak for itself. Note that if the user specifies a symbol in a Symbol Map whose associated absolute value has another symbol associated therewith from the collection of Software Symbols, the Analysis Symbol is the one used in the Trace List. The net effect of this is to allow the user to rename a Software Symbol during the debugging process without editing any source programs and without any recompiling, reassembling, and reloading. The following remarks apply to trace lists including source line numbers and source lines, such as appearing in Appendices T and U, respectively. Line numbers are generated by the compiler and appear in the :asmb -- sym file. A line appears in the listing as if it were a symbol, generally in its own column, and maybe extracted by an algorithm similar to that of the flow chart in FIG. 6. In particular, a minor change in connection with the "yes" path through decision 32 requires that processes 38 and 39 be adjusted to provide line numbers when required. And in the case where source lines themselves are also desired, process 30 also supplies the source line. The following remarks apply to instances where the invention is used in conjunction with Target Systems incorporating a Memory Management Unit (MMU). In such a system the MMU intercepts the memory bus between the processor and the memory. If the logic analyzer's address probes are connected to the virtual address existing between the processor and the MMU then no special considerations are required; the presence of the MMU is not discernable. However, some special actions are generally required in the case where the address probes are connected to the physical address existing between the MMU and the memory. First, the MMU generally will adjust the address of memory cycles according to an amount determined or selected by the Operating System. That amount might be the contents of some addressable register. The logic analyzer would need to monitor any write operations to that register to learn the instructions being passed to the MMU. Second, there is an alteration in the relationship of FIG. 4 for the mapping between the absolute values of the raw trace information and the available Trace Symbols and the mapping in the other direction between the symbols used in the various Trace, Format and Map Specifications and their associated absolute values. In the case of the first mappings mentioned above an associated presubtraction is applied to the physical address, which is then used as before. The value that is subtracted is associated with the instructions sent to the MMU and that are monitored by the Logic Analyzer. In the case of the mappings in the other direction a post-addition is applied to the resulting absolute value to produce the actual physical memory location. As before, the amount added would correspond to previous instructions supplied to the MMU and monitored by the Logic Analyzer. Another way to use the invention pertains to circumstances where a file in the Mass Memory 20 of FIG. 2 contains an image of a trace that might have at one time been in the Trace Memory 25. Such a file of a trace need not have even originated with the Logic State Analyzer Module 8; the data therein may have been gathered under entirely different circumstances and arrived at the Mass Memory 20 by any of a number of convenient means, including a removable recording medium and transmission over suitable data links. Once in the Mass Memory 20, such a file may be operated upon by the invention as if it actually came from the Trace Memory 25. TABLE I______________________________________Index to the AppendicesAPPENDIX DESCRIPTION______________________________________A MAIN sourceB FACTOR SourceC DATA --BLOCK assembly listingD MAIN expanded compiler listingE FACTOR expanded compiler listingF PARAMETER assembly listingG MULTIPLY assembly listingH BOOLEANIN assembly listingI Linker Load MapJ Format SpecificationK Conventional Trace SpecificationL Conventional Trace ListM Map SpecificationN Format Specification with Default mapO Trace Specification with Analysis SymbolsP Trace List with Analysis SymbolsQ Map Specification with Software SymbolsR Trace Specification with Trace SymbolsS Trace List with Trace SymbolsT Trace List with source line numbers and Trace SymbolsU Full Trace List with source lines and Trace Symbols______________________________________ ##SPC1##

A logic state analyzer allows a user to include symbols defined in source program listings, as well as other specially defined symbols, in the trace specification. Such symbols represent unique individual values or ranges of values. The resulting trace list includes these symbols, and where possible, all address, operands, etc., are expressed in such terms. When those symbols are relocatable entities produced by compilers and assemblers the result is that the user is freed from having to duplicate the relocation process to specify absolute values in the trace specification, and later reverse it to interpret absolute values in the listing in terms of symbols originally defined in the source programming. A further result is that the states within an arbitrary finite state machine can be assigned descriptive labels, with the trace specification and trace listing subsequently expressed in those terms. Trace values can also be represented relative to a symbol. The same principles are extendable to handle memory segment offsets invoked by memory management units that automatically convert a relocated virtual address emitted by a processor into a dynamically adjusted run time physical address actually sent to the memory. According to a preferred embodiment of the invention the analyzer makes use of various symbol tables produced by any associated assemblers and compilers, as well as of any additional special symbol definitions desired by the user. The analyzer provides absolute values for these symbols by application of the load map produced during the relocation of the various programs into the target system monitored by the logic analyzer.

FIELD OF THE INVENTION [0001] The present invention relates generally to a modified external nozzle design for use in the outlet of a bowl of a disc centrifuge that reduces wear on the top surface of the nozzles. BACKGROUND OF THE INVENTION [0002] Centrifugal machines of a nozzle type typically include a rotor or rotating bowl defining a separating chamber containing a stack of separating discs for effecting a two-fraction separation of a feed slurry. The feed slurry is separated into a heavy discharge slurry, or underflow fraction, which is delivered outside the rotor by a plurality of nozzles supported within the outer wall of the rotor. Generally, the plurality of nozzles are circumferentially positioned around the outermost periphery of the rotor. Each nozzle includes an inlet portion in communication with an interior area defined by the rotor bowl and an outlet to allow separated material to escape from the rotor bowl. A light fraction or separated liquid is removed from the rotor by overflow from the top end of the machine. [0003] In the oil sands industry, disc centrifuges are commonly used for de-sanding bitumen froth recovered from oil sands using a hot or warm water-based extraction process. Typically, bitumen froth comprises about 60% bitumen, 30% solids and 10% water. The bitumen froth is diluted with a solvent, such as naphtha solvent, followed by bitumen separation in a sequence of scroll and disc centrifuges. The inertial forces of the disc centrifuges cause water and solids to migrate outwardly towards the spinning bowl wall. The bitumen works its way inwardly and accumulates near the center of the disc stack, where it is removed as the light phase discharge. Thus, the water and the solids are discharged from the bowl through the plurality of nozzles, which are fitted into apertures formed in the bowl wall. [0004] Hence, in service, the nozzles are subject to high wear rates, both internally, i.e., the nozzle bore, and externally, i.e., the sleeve which enveloped the passageway or bore of the nozzle. This leads to significant replacement and repair costs. Canadian Patent No. 2,084,974 addresses the issue of internal erosion by modifying the longitudinal bore, which generally comprises two straight segments joined by an elbow, by having the surface of the bore smoothly curved and continuous through the change of direction (i.e., elbow), to prevent the eddying associated with change-of-angle linear junctions of the segments, thereby altering the flow pattern of the stream with a significant reduction in wear. [0005] As shown herein in FIG. 1 , labeled Prior Art, the nozzle 1 of Canadian Patent No. 2,084,974, owned by the present applicant, comprises a duplex body formed by an inner sleeve 3 having a top surface 9 and a contiguous outer sleeve 4 having a protruding collar 14 . The outer sleeve 4 forms a sheath which supports the inner sleeve 3 along most of its length. Typically, the inner sleeve is formed of titanium carbide and the outer sleeve 4 of stainless steel. The inner sleeve 3 forms an internal longitudinal bore 5 comprising an inlet segment 6 and an outlet segment 7 joined by an elbow segment 8 . The surface of the elbow segment 8 is curved and smooth, being free of linear junction lines at the joinder of bore surfaces disposed at different angles. [0006] However, it was discovered that the nozzle in FIG. 1 still showed considerable wear at the top 9 of inner sleeve 3 . The present invention addresses this issue of external erosion of disc centrifuge nozzles, in particular, at the top 9 of inner sleeve 3 . SUMMARY OF THE INVENTION [0007] The present applicant used fluid dynamic modeling, e.g., Computational Fluid Dynamics or CFD, to study wear patterns on the outer surface of nozzles routinely used in disc centrifuges. Initially, it was believed that erosion problems at the top of the inner sleeve of the nozzles could be remedied simply by extending (i.e., thickening) the top of the inner sleeve to produce a nozzle having a raised or elevated portion with a blunted nose at the front end. Hence, the inner sleeve could still fit into the outer sleeve, however, it would now have an elevated region. [0008] However, it was discovered that such nozzles were still having significant erosion problems and a horse shoe-like wear pattern was observed. Such wear pattern was confirmed with the use of CFD, where stagnation was observed due to the blunted nose and the formation of a horse shoe vortex was also observed in this region. It was surprisingly discovered that by tapering the front (i.e., eliminating the blunted nose) of the elevated region of the inner sleeve to form a more wedge shaped front end (a tapered front end), i.e., making it more streamlined, the external wear of these nozzles greatly improved, as the horse shoe eddies and the like were substantially reduced. [0009] Without being bound to theory, it is believed that having a sharp transition point between the inner sleeve and the outer sleeve of the nozzle (e.g., such as a 90° transition point) causes excessive wear at that point due to the production of various eddies, such as horseshoe eddies. [0010] Thus, broadly stated, in one aspect of the invention, a nozzle for use in the bowl of a disc centrifuge is provided, comprising: an inner sleeve forming a longitudinally extending passageway, the inner sleeve having an elevated region at its top, the elevated region having an extended front end; and an outer sleeve for supporting the inner sleeve along most of its length, the outer sleeve having a collar with an outermost edge at its top; whereby when the inner sleeve is inserted into the outer sleeve, the elevated region of the inner sleeve extends past the collar of the outer sleeve and the extended front end of the elevated region extends towards the outermost edge of the outer sleeve collar. DESCRIPTION OF THE DRAWINGS [0014] Referring to the drawings wherein like reference numerals indicate similar parts throughout the several views, several aspects of the present invention are illustrated by way of example, and not by way of limitation, in detail in the figures, wherein: [0015] FIG. 1 is a cross-sectional view of a prior embodiment of a disc centrifuge nozzle. [0016] FIG. 2 is a cross-sectional view of the nozzle of FIG. 1 where the inner sleeve has an elevated region at its top with a blunted nose at its front end. [0017] FIG. 3 is a cross-sectional view of the nozzle of FIG. 2 where the inner sleeve has an elevated region at its top with a tapered wedge shaped front end. [0018] FIG. 4 is a perspective view of the elevated region of the nozzle in FIG. 2 . [0019] FIG. 5 is a perspective view of the elevated region of the nozzle in FIG. 3 . [0020] FIG. 6A is a perspective front view of the inner sleeve of the nozzle in FIG. 3 . [0021] FIG. 6B is a perspective side view of the inner sleeve of the nozzle in FIG. 3 . [0022] FIG. 6C is a perspective top view of the inner sleeve of the nozzle in FIG. 3 . [0023] FIG. 7 shows the velocity magnitude in rotating frame of a nozzle having a blunted cap (Panel A) and a nozzle having a streamlined cap (Panel B). [0024] FIG. 8 shows the wall shear stress distribution on rotating parts for a nozzle having a blunted cap (Panel A) and a nozzle having a streamlined cap (Panel B). [0025] FIG. 9 shows the swirl in y-direction (flow direction) for a nozzle having a blunted cap (Panel A) and a nozzle having a streamlined cap (Panel B). DESCRIPTION OF THE PREFERRED EMBODIMENT [0026] The detailed description set forth below in connection with the appended drawing is intended as a description of various embodiments of the present invention and is not intended to represent the only embodiments contemplated by the inventor. The detailed description includes specific details for the purpose of providing a comprehensive understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without these specific details. [0027] With reference to FIG. 2 , nozzle 101 comprises a duplex body formed by an inner sleeve 103 having a top surface 109 , the inner sleeve further comprising an elevated region or cap 116 at its top for further wear protection. Nozzle 101 further comprises a contiguous outer sleeve 104 having a protruding collar 114 . The outer sleeve 104 forms a sheath which supports the inner sleeve 103 along most of its length so that the elevated region or cap 116 of inner sleeve 103 protrudes from outer sleeve 104 . In one embodiment, cap 116 is made from the same material as inner sleeve 103 and generally cap 116 and inner sleeve 103 are formed as a unitary body. Typically, the inner sleeve 103 is formed of titanium carbide and the outer sleeve 104 of stainless steel. Cap 116 further comprises a front snubbed or blunted nose 118 . The snubbed nose 118 at the front end can be seen in a perspective view in FIG. 4 . [0028] The inner sleeve 103 forms an internal longitudinal bore 105 comprising an inlet segment 106 and an outlet segment 107 joined by an elbow segment 108 . The surface of the elbow segment 108 is curved and smooth, being free of linear junction lines at the joinder of bore surfaces disposed at different angles. [0029] However, it was discovered that the nozzle in FIG. 2 still showed considerable wear, in particular, at the junction 112 of inner sleeve 103 and outer sleeve 104 . The extended collar 114 and the snubbed nose 118 formed an angle (θ) of about 90° and formed a substantial step down from the top surface 109 of cap 116 and the top surface of extended collar 114 . It was observed that there was a horse-shoe wear pattern that developed at the top 109 of inner sleeve 103 . [0030] The present invention addresses this issue of external erosion of disc centrifuge nozzles, in particular, at the top 109 of inner sleeve 103 . An embodiment of the present invention is shown in FIG. 3 . In FIG. 3 , nozzle 201 comprises a duplex body formed by an inner sleeve 203 having a top surface 209 , the inner sleeve 203 further comprising an elevated region or cap 216 at its top for further wear protection. Nozzle 201 further comprises a contiguous outer sleeve 204 having a protruding collar 214 . The outer sleeve 204 forms a sheath which supports the inner sleeve 203 along most of its length so that the elevated region or cap 216 of inner sleeve 203 protrudes from outer sleeve 204 . In one embodiment, cap 216 is made from the same material as inner sleeve 203 and generally cap 216 and inner sleeve 203 are formed as a unitary body. Typically, the inner sleeve 203 is formed of titanium carbide and the outer sleeve 204 of stainless steel. Cap 216 further comprises an extended front end 222 , forming a tapered wedge shaped front end. The extended wedge shaped front end 222 can be seen in a perspective view in FIG. 5 . The front end 222 covers a substantial portion of the collar 214 ; however, preferably, a portion 220 of the outer sleeve collar 214 upstream of the front end 222 remains uncovered to ensure wear occurs on the nozzle and not the bowl of the disc centrifuge. [0031] The inner sleeve 203 forms an internal longitudinal bore 205 comprising an inlet segment 206 and an outlet segment 207 joined by an elbow segment 208 . The surface of the elbow segment 208 is curved and smooth, being free of linear junction lines at the joinder of bore surfaces disposed at different angles. [0032] It was discovered that the nozzle in FIG. 3 showed considerably reduced wear, in particular, at the junction 212 of inner sleeve 203 and outer sleeve 204 . The outer sleeve collar 214 and the extended front end 222 are secured to one another so that there is no space between the two parts. Further, the angle (θ) is much greater than 90°, e.g., in this embodiment around 150°, and substantially no step down is seen from the top surface 209 of cap 216 and the top surface of extended collar 214 . Thus, it was observed that there was little or no horse-shoe wear pattern that developed at the top 209 of inner sleeve 203 . [0033] The inner sleeve 203 is shown in three perspective views in FIG. 6 . In particular, FIG. 6A shows the inner sleeve 203 looking towards the front end 222 of cap 216 . FIG. 6B shows inner sleeve 203 from the side which shows the extended rounded front end 222 . FIG. 6C shows inner sleeve 203 looking down on cap 216 and shows the extended rounded EXAMPLE 1 [0034] Computational fluid dynamics, usually abbreviated as CFO, is a branch of fluid mechanics that uses numerical methods and algorithms to solve and analyze problems that involve fluid flows. Computers are used to perform the calculations required to simulate the interaction of liquids and gases with surfaces defined by boundary conditions. Ongoing research yields software that improves the accuracy and speed of complex simulation scenarios such as transonic or turbulent flows. [0035] CFD was used to test nozzles 101 and 201 , as shown in FIG. 2 and FIG. 3 , respectively, and having caps 116 and 216 , respectively. FIG. 7 shows the velocity magnitude in rotating frame of a nozzle having a blunted cap 116 (Panel A) and a nozzle having a streamlined cap 216 (Panel B). It can be seen that when the front of the nozzle cap is blunted, as in Panel A, there is stagnation in front of the nozzle (circle). However, when the front of the nozzle cap is extended and streamlined, as in Panel B, there is little or no stagnation in front of the nozzle (circle). [0036] FIG. 8 shows the wall shear stress distribution on rotating parts for a nozzle having a blunted cap 116 (Panel A) and a nozzle having a streamlined cap 216 (Panel B). Essentially, the radial velocity was analyzed 1 mm outside the bowl wall. It can be seen that when the front of the nozzle cap is blunted, as in Panel A, a horse shoe vortex 150 was observed (circle). However, when the front of the nozzle cap was extended and streamlined, as in Panel B, little or no horse shoe vortex was observed (circle). [0037] FIG. 9 shows the swirl in y-direction (flow direction) for a nozzle having a blunted cap 116 (Panel A) and a nozzle having a streamlined cap 216 (Panel B). Essentially, the vortex strength was analyzed 1 mm outside the bowl wall. It can be seen that when the front of the nozzle cap is blunted, as in Panel A, a horse shoe vortex 150 was also observed. However, when the front of the nozzle cap was extended and streamlined, as in Panel B, little or no horse shoe vortex was observed. [0038] Thus, it was observed that the elevated (above bowl surface) stagnation region responsible for the horse shoe vortex of the nozzle of FIG. 2 could be corrected, i.e., substantially removed, by the addition of a more wedge shaped front end. This change in geometry reduced/eliminated the horse shoe vortex and, hence, the horse shoe vortex wear pattern. Thus, a nozzle with an extended and rounded front end on its inner sleeve cap will have less erosion on the top of the inner sleeve and therefore a greater life span. [0039] From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention. However, the scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.

A nozzle for use in the bowl of a disc centrifuge is provided, comprising an inner sleeve forming a longitudinally extending passageway, the inner sleeve having an elevated region at its top, the elevated region having an extended front end; and an outer sleeve for supporting the inner sleeve along most of its length, the outer sleeve having a collar with an outermost edge at its top; whereby when the inner sleeve is inserted into the outer sleeve, the elevated region of the inner sleeve extends past the collar of the outer sleeve and the extended front end of the elevated region extends towards the outermost edge of the outer sleeve collar.

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] This invention relates in particular to the semiconductor device layout inspection method for taking measures of the wire formation defects. [0003] 2. Description of the Prior Art [0004] Conventionally, the following measurements have been carried out in order to prevent the occurrence of hillocks in wires of a large area covered with an insulating film, which is a thin film and in order to prevent wire defects from occurring at the time of manufacturing the semiconductor device. [0005] The width and the length of a wire is divided into pieces no greater than the critical dimensions so that no hillocks will occur in a semiconductor device having wires of a large area formed on a semiconductor substrate via an insulating film as shown, for example, in Japanese unexamined patent publication H8 (1996)-115914. Then the respective wires that have been divided are electrically connected to each other by means of other wires. The wires for connecting the wires that have been divided are placed in a non-overlapping manner so that no hillocks will occur in the combination with the wires that have been divided. [0006] Wire uplift due to a hillock and a defect of a connection portion of a contact hole and a wire may occur in the step of ashing or of washing in the case wherein the contact holes are provided in a high concentration in wires of a large area according to a conventional manufacture of a semiconductor device. Thereby, a disconnection of a wire, a breakdown of a wire and a surface peeling will occur in a portion of wires of a large area due to the heat at the time of deposition of a CVD film as an upper layer. SUMMARY OF THE INVENTION [0007] An object of this invention is to provide a semiconductor device layout inspection method wherein a portion of a high density of contact holes in wires of a large area where wire defects will occur can be detected at the chip level. [0008] The semiconductor device layout inspection method according to the first invention is a method for inspecting formation defects that will occur in wires of a chip layout, wherein the wire formation defects are detected by checking the relationship between the layout of the contact holes in the wires and the layout of the wires. [0009] According to the first invention the wire formation defects are detected by checking the relationship between the layout of the contact holes in the wires and the layout of the wires and, therefore, occurrence of hillocks can be prevented so that wire defects can be prevented from occurring at the time of manufacturing a semiconductor device in the case wherein the density of the contact holes is high in the wires of a large area. [0010] It is preferable in the method according to the first invention for the layout of wires where wire formation defects have been detected to be corrected. [0011] Thus, defects of wire peeling due to hillocks on wires having a wide width can be reduced in the case wherein the layout of wires where wire formation defects have been detected is corrected. [0012] The semiconductor device layout inspection method according to the second invention is a method for inspecting formation defects that will occur in wires of a chip layout, wherein the wire formation defects are detected by providing limitation to the area ratio of the total area of the wires of the same node to the total area of the contact holes in the wires of the same node of the chip layout so that existence of defects is determined based on this limitation. [0013] According to the second invention, the wire formation defects are detected by providing limitation to the area ratio of the total area of the wires of the same node to the total area of the contact holes in the wires of the same node of the chip layout so that existence of defects is determined based on this limitation and, therefore, defects that exceed the area ratio limitation can be detected at the layout designing stage and, thereby, formation defects such as wire disconnections, breakdowns and peelings from the surface of the wires of a large area due to hillocks and failures in connections between the wires and contact holes can be avoided. [0014] The semiconductor device layout inspection method according to the third invention is a method for inspecting formation defects that will occur in wires of a chip layout, wherein the wire formation defects are detected by providing limitation to the number of contact holes in the wires of the same node so that existence of defects is determined based on this number limitation. [0015] According to the third invention, the wire formation defects are detected by providing limitation to the number of contact holes in the wires of the same node so that existence of defects is determined based on this number limitation and, therefore, defects that exceed the number limitation can be detected at the layout designing stage and, thereby, formation defects such as wire disconnections, breakdowns and peelings from the surface of the wires of a large area due to hillocks and failures in connections between the wires and contact holes can be avoided. [0016] The semiconductor device layout inspection method according to the fourth invention is a method for inspecting formation defects that will occur in wires of a chip layout, wherein the wire formation defects are detected by providing limitation to the number of contact holes in the wires having a constant width so that existence of defects is determined based on this number limitation. [0017] According to the fourth invention the wire formation defects are detected by providing limitation to the number of contact holes in the wires having a constant width so that existence of defects is determined based on this number limitation and, therefore, defects that exceed the number limitation can be detected at the layout designing stage and, thereby, formation defects such as wire disconnections, breakdowns and peelings from the surface of the wires of a large area due to hillocks and failures in connections between the wires and contact holes can be avoided. [0018] The semiconductor device layout inspection method according to the fifth invention is a method for inspecting formation defects that will occur in wires of a chip layout, wherein the wire formation defects are detected by providing limitation to the total area of contact holes in the wires having a constant width so that existence of defects is determined based on this area limitation. [0019] According to the fifth invention the wire formation defects are detected by providing limitation to the total area of contact holes in the wires having a constant width so that existence of defects is determined based on this area limitation and, therefore, defects that exceed the area limitation can be detected at the layout designing stage and, thereby, formation defects such as wire disconnections, breakdowns and peelings from the surface of the wires of a large area due to hillocks and failures in connections between the wires and contact holes can be avoided. [0020] The semiconductor device layout inspection method according to the sixth invention is a method for inspecting formation defects that will occur in wires of a chip layout, comprising: the step of calculating the total area of the wires of the same node and the total area of the contact holes in the wires of the same node; and the step of determining the area limitation value of the contact holes in accordance with the total area of the wires of the same node, wherein the area of the same node is detected as a wire formation defect when the total area of the contact holes is equal to, or is greater than, the area limitation value. [0021] According to the sixth invention the step of calculating the total area of the wires of the same node and the total area of the contact holes in the wires of the same node; and the step of determining the area limitation value of the contact holes in accordance with the total area of the wires of the same node are included, wherein the area of the same node is detected as a wire formation defect when the total area of the contact holes is equal to, or is greater than, the area limitation value and, therefore, the limitation of the total area of the contact holes varies in accordance with the total area of the wires of the same node and, thereby, the same working effects as of the second invention can be gained and the limitation value can be microscopically adjusted with a high precision in accordance with the width/area of the wires. [0022] The semiconductor device layout inspection method according to the seventh invention is a method for inspecting formation defects that will occur in wires of a chip layout, comprising: the step of calculating the total area of the wires of the same node and the number of the contact holes in the wires of the same node; and the step of determining the number limitation value of the contact holes in accordance with the total area of the wires of the same node, wherein the area of the same node is detected as a wire formation defect when the number of the contact holes is equal to, or is greater than, the number limitation value. [0023] According to the seventh invention, the step of calculating the total area of the wires of the same node and the number of the contact holes in the wires of the same node; and the step of determining the number limitation value of the contact holes in accordance with the total area of the wires of the same node, are provided wherein the area of the same node is detected as a wire formation defect when the number of the contact holes is equal to, or is greater than, the number limitation value and, therefore, the number limitation of the contact holes varies in accordance with the total area of the wires of the same node and, thereby, the same working effects as of the third invention can be gained and the limitation value can be microscopically adjusted with a high precision in accordance with the width/area of the wires. [0024] The semiconductor device layout inspection method according to the eighth invention is a method for inspecting formation defects that will occur in wires of a chip layout, comprising: the step of calculating the number of the contact holes in the wires having a constant width; and the step of determining the number limitation value of the contact holes that varies in accordance with the wire width, wherein the area concerning the contact holes is detected as a wire formation defect when the number of the contact holes is equal to, or is greater than, the number limitation value. [0025] According to the eighth invention, the step of calculating the number of the contact holes in the wires having a constant width; and the step of determining the number limitation value of the contact holes that varies in accordance with the wire width, are provided wherein the area concerning the contact holes is detected as a wire formation defect when the number of the contact holes is equal to, or is greater than, the number limitation value and, therefore, the number limitation of the contact holes varies in accordance with the width of the wires and, thereby, the same working effects as of the fourth invention can be gained and the limitation value can be microscopically adjusted with a high precision in accordance with the width/area of the wires. [0026] The semiconductor device layout inspection method according to the ninth invention for inspecting formation defects that will occur in wires of a chip layout, comprising: the step of calculating the total area of the contact holes in the wires having a constant width; and the step of determining the area limitation value of the contact holes that varies in accordance with the wire width, wherein the area concerning the contact holes is detected as a wire formation defect when the total area of the contact holes is equal to, or is greater than, the area limitation value. [0027] According to the ninth invention, the step of calculating the total area of the contact holes in the wires having a constant width; and the step of determining the area limitation value of the contact holes that varies in accordance with the wire width are provided, wherein the area concerning the contact holes is detected as a wire formation defect when the total area of the contact holes is equal to, or is greater than, the area limitation value and, therefore, the area limitation of the contact holes varies in accordance with the width of the wires and, thereby, the same working effects as of the fifth invention can be gained and the limitation value can be microscopically adjusted with a high precision in accordance with the width/area of the wires. [0028] The semiconductor device layout inspection method according to the tenth invention is a method for inspecting formation defects that will occur in wires of a chip layout, comprising: the step of dividing the entire area of the chip layout into a plurality of inspection regions; and the step of providing limitation to the number of the contact holes in the wires having a constant width in an inspection region from among the plurality of inspection regions so that a wire formation defect is detected by determining the existence of a defect based on this number limitation, wherein the step of detecting a wire formation defect is repeated in a scanning manner until the plurality of inspection regions on the entire surface of the chip layout is inspected. [0029] According to the tenth invention, the step of dividing the entire area of the chip layout into a plurality of inspection regions; and the step of providing limitation to the number of the contact holes in the wires having a constant width in an inspection region from among the plurality of inspection regions so that a wire formation defect is detected by determining the existence of a defect based on this number limitation are provided, wherein the step of detecting a wire formation defect is repeated in a scanning manner until the plurality of inspection regions on the entire surface of the chip layout is inspected and, therefore, the same inspection as of the fourth invention is carried out in an inspection region and such an inspection is repeated for every inspection region, the total of which covers the entire surface so that the inspection of the entire surface of the layout is completed. A local portion wherein contacts are located in a high density can be inspected so as to avoid a formation defect by dividing the entirety of the chip into regions in contrast to the inspection of the entire surface of the chip. [0030] The entire surface inspection for inspecting the entire chip surface of the chip layout and a partial inspection for inspecting a portion of a chip may have different scanning intervals of the inspection regions in the configuration of the tenth invention. [0031] Thus the entire surface inspection for inspecting the entire chip surface of the chip layout and a partial inspection for inspecting a portion of a chip may have different scanning intervals of the inspection regions and, therefore, an appropriate scanning interval can be selected in accordance with a purpose such that the processing turn around time (hereinafter abbreviated as TAT) is prioritized for the inspection of the entire surface of the chip and a detailed inspection is prioritized for a partial inspection. [0032] The entire surface inspection for inspecting the entire chip surface of the chip layout and a partial inspection for inspecting a portion of the chip may have different sizes of the inspection regions in the configuration of the tenth invention. [0033] Thus, an appropriate size of the inspection region can be selected in accordance with a purpose such that the processing TAT is prioritized for the inspection of the entire chip surface and a detailed inspection is prioritized for a partial inspection. [0034] It is preferable to provide limitation to the number of the contact holes in wires having a constant width after wires connected to contact holes of which the number is less than a constant number in the chip layout has been removed in advance in the configuration of the fourth invention. [0035] Thus, limitation is provided to the number of the contact holes in wires having a constant width after wires connected to contact holes of which the number is less than a constant number in the chip layout has been removed in advance and, therefore, the minimum number of contact holes in the wires having a certain possibility of the occurrence of defects is defined so that the wires which do not require inspection are removed in accordance with the number of contact holes before the number limitation of the contact holes is provided in the same manner as in the fourth invention and, thereby, the process TAT can be shortened. [0036] It is preferable to provide limitation to the number of the contact holes in wires having a constant width in inspection regions that have been limited to the inspection regions having contact holes of which the number is equal to, or greater than, a constant number from among the plurality of inspection regions in the configuration of the tenth invention. [0037] Thus, limitation is provided to the number of the contact holes in wires having a constant width in inspection regions that have been limited to the inspection regions having contact holes of which the number is equal to, or greater than, a constant number from among the plurality of inspection regions and, therefore, the number limitation of the contact holes can be carried out in the same manner as in the tenth invention without selecting inspection regions which do not require inspections in accordance with the number of contact holes so that the processing TAT can be shortened. [0038] The semiconductor device layout inspection method according to the eleventh invention is a method for inspecting formation defects that will occur in wires of a chip layout, comprising: the step of dividing the entire area of the chip layout into a plurality of inspection regions; and the step of providing limitation to the area ratio of the total area of the wires of the same node to the total area of the contact holes in the wires of the same node using an antenna check in an inspection region from among the plurality of inspection regions so that a wire formation defect is detected by determining the existence of a defect based on this limitation, wherein the step of detecting a wire formation defect is repeated in a scanning manner until the plurality of inspection regions on the entire surface of the chip layout is inspected. [0039] According to the eleventh invention the step of dividing the entire area of the chip layout into a plurality of inspection regions; and the step of providing limitation to the area ratio of the total area of the wires of the same node to the total area of the contact holes in the wires of the same node using an antenna check in an inspection region from among the plurality of inspection regions so that a wire formation defect is detected by determining the existence of a defect based on this limitation, are provided wherein the step of detecting a wire formation defect is repeated in a scanning manner until the plurality of inspection regions on the entire surface of the chip layout is inspected and, therefore, the same inspection as in the second invention is carried out in an inspection region and such an inspection is repeated in a scanning manner for every inspection regions of which the total covers the entire surface so that the inspection of the entire surface of the layout is completed. Therefore, formation defects such as wire disconnections, breakdowns and peelings from the surface of the wires of a large area due to hillocks and failures in connections between the wires and contact holes can be avoided. In addition, the ratio of the conventional gates to the contacts connected to the gates is calculated according to the antenna check, which can be applied to the above inspection by using wires instead of the gates. [0040] The semiconductor device layout inspection method according to the twelfth invention is a method for inspecting formation defects that will occur in wires of a chip layout, comprising: the step of defining a partial inspection region in the chip layout; and the step of providing limitation to the area ratio of the total area of the wires of the same node to the total area of the contact holes in the wires of the same node using an antenna check in the partial inspection region so that a wire formation defect is detected by determining the existence of a defect based on this limitation, wherein the step of detecting a wire formation defect is repeated in a scanning manner using a density check until the total of partial inspection regions cover the entire surface of the chip layout. [0041] According to the twelfth invention the step of defining a partial inspection region in the chip layout; and the step of providing limitation to the area ratio of the total area of the wires of the same node to the total area of the contact holes in the wires of the same node using an antenna check in the partial inspection region so that a wire formation defect is detected by determining the existence of a defect based on this limitation are provided, wherein the step of detecting a wire formation defect is repeated in a scanning manner using a density check until the total of partial inspection regions cover the entire surface of the chip layout and, therefore, the same inspection as in the second invention is carried out within a partial inspection region and such an inspection is repeated in a scanning manner for every partial inspection region of which the total covers the entire surface and, thereby, the inspection of the entire surface of the layout is completed. Thus, formation defects such as wire disconnections, breakdowns and peelings from the surface of the wires of a large area due to hillocks and failures in connections between the wires and contact holes can be avoided. In addition, the ratio of the conventional gates to the contacts connected to the gates is calculated according to the antenna check, which can be applied to the above inspection by using wires instead of the gates. BRIEF DESCRIPTION OF THE DRAWINGS [0042] [0042]FIG. 1 is a layout diagram showing wire and contact hole layers in a semiconductor layout utilized for an embodiment of this invention; [0043] [0043]FIG. 2 is a dataflow diagram showing a flow of data at the time of inspection according to the first embodiment of this invention; [0044] [0044]FIG. 3 is a flowchart showing an inspection algorithm according to the first embodiment of this invention; [0045] [0045]FIGS. 4A, 4B, 4 C and 4 D are diagrams showing an inspection process according to the first embodiment of this invention; [0046] [0046]FIG. 5 is a dataflow diagram showing a flow of data at the time of inspection according to the second embodiment of this invention; [0047] [0047]FIG. 6 is a flowchart showing an inspection algorithm according to the second embodiment of this invention; [0048] [0048]FIGS. 7A, 7B, 7 C and 7 D are diagrams showing an inspection process according to the second embodiment of this invention; [0049] [0049]FIG. 8 is a dataflow diagram showing a flow of data at the time of inspection according to the third embodiment of this invention; [0050] [0050]FIG. 9 is a flowchart showing an inspection algorithm according to the third embodiment of this invention; [0051] [0051]FIGS. 10A, 10B, 10 C and 10 D are diagrams showing an inspection process according to the third embodiment of this invention; [0052] [0052]FIG. 11 is a dataflow diagram showing a flow of data at the time of inspection according to the fourth embodiment of this invention; [0053] [0053]FIG. 12 is a flowchart showing an inspection algorithm according to the fourth embodiment of this invention; [0054] [0054]FIGS. 13A, 13B, 13 C and 13 D are diagrams showing an inspection process according to the fourth embodiment of this invention; [0055] [0055]FIG. 14 is a dataflow diagram showing a flow of data at the time of inspection according to the fifth embodiment of this invention; [0056] [0056]FIG. 15 is a flowchart showing an inspection algorithm according to the fifth embodiment of this invention; [0057] [0057]FIGS. 16A, 16B, 16 C, 16 D and 16 E are diagrams showing an inspection process according to the fifth embodiment of this invention; [0058] [0058]FIG. 17 is a dataflow diagram showing a flow of data at the time of inspection according to the sixth embodiment of this invention; [0059] [0059]FIG. 18 is a flowchart showing an inspection algorithm according to the sixth embodiment of this invention; [0060] [0060]FIGS. 19A, 19B, 19 C, 19 D and 19 E are diagrams showing an inspection process according to the sixth embodiment of this invention; [0061] [0061]FIG. 20 is a dataflow diagram showing a flow of data at the time of inspection according to the seventh embodiment of this invention; [0062] [0062]FIG. 21 is a flowchart showing an inspection algorithm according to the seventh embodiment of this invention; [0063] [0063]FIGS. 22A, 22B, 22 C, 22 D and 22 E are diagrams showing an inspection process according to the seventh embodiment of this invention; [0064] [0064]FIG. 23 is a dataflow diagram showing a flow of data at the time of inspection according to the eighth embodiment of this invention; [0065] [0065]FIG. 24 is a flowchart showing an inspection algorithm according to the eighth embodiment of this invention; [0066] [0066]FIGS. 25A, 25B, 25 C, 25 D and 25 E are diagrams showing an inspection process according to the eighth embodiment of this invention; [0067] [0067]FIG. 26 is a dataflow diagram showing a flow of data at the time of inspection according to the ninth embodiment of this invention; [0068] [0068]FIG. 27 is a flowchart showing an inspection algorithm according to the ninth embodiment of this invention; [0069] [0069]FIGS. 28A, 28B, 28 C and 28 D are diagrams showing a region wherein the number of contact holes is collectively inspected according to the ninth embodiment of this invention; [0070] [0070]FIGS. 29A, 29B, 29 C, 29 D and 29 E are diagrams showing an inspection process according to the ninth embodiment of this invention; [0071] [0071]FIGS. 30A, 30B, 30 C, 30 D, 30 E and 30 F are diagrams showing an inspection process according to the ninth embodiment of this invention; [0072] [0072]FIG. 31 is a dataflow diagram showing a flow of data at the time of inspection according to the tenth embodiment of this invention; [0073] [0073]FIG. 32 is a flowchart showing an inspection algorithm according to the tenth embodiment of this invention; [0074] [0074]FIGS. 33A, 33B, 33 C, 33 D and 33 E are diagrams showing an inspection process according to the tenth embodiment of this invention; [0075] [0075]FIG. 34 is a dataflow diagram showing a flow of data at the time of inspection according to the eleventh embodiment of this invention; [0076] [0076]FIG. 35 is a flowchart showing an inspection algorithm according to the eleventh embodiment of this invention; [0077] [0077]FIGS. 36A, 36B, 36 C and 36 D are diagrams showing a region wherein the number of contact holes is collectively inspected according to the eleventh embodiment of this invention; [0078] [0078]FIGS. 37A, 37B, 37 C, 37 D and 37 E are diagrams showing an inspection process according to the eleventh embodiment of this invention; [0079] [0079]FIGS. 38A, 38B, 38 C and 38 D are diagrams showing an inspection process according to the eleventh embodiment of this invention; [0080] [0080]FIGS. 39A, 39B, 39 C, 39 D and 39 E are diagrams showing an inspection process according to the eleventh embodiment of this invention; [0081] [0081]FIG. 40 is a dataflow diagram showing a flow of data at the time of inspection according to the twelfth embodiment of this invention; [0082] [0082]FIG. 41 is a flowchart showing an inspection algorithm according to the twelfth embodiment of this invention; [0083] [0083]FIGS. 42A, 42B, 42 C and 42 D are diagrams showing a region wherein the number of contact holes is collectively inspected according to the eleventh embodiment of this invention; [0084] [0084]FIGS. 43A, 43B, 43 C and 43 D are diagrams showing an inspection process according to the twelfth embodiment of this invention; [0085] [0085]FIG. 44 is a dataflow diagram showing a flow of data at the time of inspection according to the thirteenth embodiment of this invention; [0086] [0086]FIG. 45 is a flowchart showing an inspection algorithm according to the thirteenth embodiment of this invention; and [0087] [0087]FIGS. 46A, 46B, 46 C and 46 D are diagrams showing an inspection process according to the thirteenth embodiment of this invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0088] The first embodiment of this invention is described below in reference to FIGS. 1, 2, 3 , 4 A, 4 B, 4 C and 4 D. [0089] [0089]FIG. 1 is a layout diagram showing wire and contact hole layers in a semiconductor layout that is used for the embodiment of this invention. [0090] In FIG. 1, symbol 11 indicates the outermost periphery of a chip, symbol 12 indicates a layout of a wire layer and symbol 13 indicates a layout of a contact hole layer. [0091] [0091]FIG. 3 is a flowchart showing an inspection algorithm according to the first embodiment of this invention and FIGS. 4A, 4B, 4 C and 4 D are diagrams showing an inspection process according to the first embodiment of this invention. In the following, the inspection process is described in reference to the flowchart. [0092] This semiconductor device layout inspection method is a method for inspecting formation defects that will occur in wires of a large area in a chip layout, wherein the area ratio of the total area of the wires of the same node to the total area of the contact holes in the wires of the same node is limited in the chip layout and the wire formation defects are detected by determining whether or not defects exist based on this limitation. [0093] In this case, as shown in FIGS. 4A, 4B and 4 C, a region 19 having four sides of the minimum wire interval W is defined in a layout 14 and a wire 15 which region 19 overlaps is selected from among the wires in layout 14 . Since region 19 has the minimum wire interval, the selected wire 15 always becomes of the same node. In the case wherein region 19 does not overlap the wire of layout 14 , region 19 is shifted by minimum wire interval W so as not to overlap the previous position within layout 14 and the next region is selected and it is determined whether or not the selected region overlaps the wire layer of layout 14 . The determination is repeated (Step 1 A) until the entire surface of the layout has completely be scanned or the next wire of the same node has been found. [0094] The area of the selected wire 15 of the same node is calculated (Step 1 B). Wire 15 having a contact hole 17 and wire 16 having a contact hole 18 are of different nodes (FIG. 4D). Contact hole 17 that overlaps wire 15 selected in step 1 A is selected (Step 1 C). The total area of contact hole 17 selected in step 1 C is calculated (Step 1 D). The area ratio is calculated (Step 1 E) from the area of wire 15 of the same node that has been calculated in step 1 B and from the total area of contact hole 17 that has been calculated in step 1 D. At this time, contact hole 17 and contact hole 18 are located in wires of different nodes and, therefore, the area ratios are separately calculated. In the case wherein the area ratio of step 1 E becomes equal to, or greater than, the limitation value, the area is detected as an error portion where wire formation defects occur (Step 1 F). [0095] Next, wires that have been selected in step 1 A are eliminated from input layout 14 (Step 1 G). Wires of the same node that have once been selected in step 1 G are eliminated from input layout 14 so as not to be selected twice and, therefore, a high speed CAD process can be implemented. It is determined (Step 1 H) whether or not region 19 selected in step 1 A has scanned the entire surface of the input layout. The procedure returns to step 1 A so as to be repeated in the case wherein region 19 that has not been scanned exists. The inspection is completed after the entire surface has been scanned. [0096] [0096]FIG. 2 is a dataflow diagram showing a flow of data at the time of inspection according to the first embodiment of this invention. In the following the dataflow is described. [0097] As shown in FIG. 2, wire data 15 is selected and outputted as the same node in the case wherein a region that overlaps wire data 15 of the inputted layout data 14 exists in same node wire recognition step 1 a wherein a region 19 of the minimum wire interval is defined. The selected wire data 15 and layout data 14 are inputted in contact recognition step 1 b so that contact hole data 17 in layout data 14 that overlaps wire data 15 is selected and outputted. The selected same node wire data 15 and the selected contact hole data 17 are inputted in area calculation step 1 c so that the respective total areas are calculated. The area ratio of the area of same node wire data 15 to the area of contact hole data 17 is calculated and outputted in area ratio calculation step 1 d , wherein the respective areas have been calculated in area calculation step 1 c. [0098] The selected wire data 15 and contact hole data 17 are outputted as errors in the case wherein the area ratio and the error conditions are compared and the area ratio does not satisfy the conditions in error determination step 1 e . Layout data 14 and wire data 15 are inputted in layout data update step 1 f and the layout data gained by subtracting wire data 15 that has been selected in same node wire recognition step 1 a from input layout data 14 is output and this outputted data is used as input layout data for the wires to be inspected next. [0099] As a result of the above described procedure locations wherein wire formation defects occur in the input layout can be detected. [0100] The second embodiment of this invention is described based on FIGS. 5, 6, 7 A, 7 B, 7 C and 7 D. [0101] [0101]FIG. 6 is a flowchart showing the inspection algorithm according to the second embodiment of this invention and FIGS. 7A, 7B, 7 C and 7 D are diagrams showing the inspection process according to the second embodiment of this invention. In the following the inspection procedure is described in accordance with the flowchart. [0102] This semiconductor device layout inspection method is a method for inspecting formation defects that occur to large area wires in the chip layout wherein the number of contact holes in wires of the same node is limited and the existence of defects is determined based on this number limitation and, thereby, the locations of wire formation defects are detected. [0103] In this case, as shown in FIGS. 7A, 7B and 7 C, a region 26 with four sides having the minimum wire interval W 2 is defined in layout 21 and wire 22 overlapped by region 26 is selected from among the wires in layout 21 . Region 26 has the minimum wire interval and, therefore, the selected wire 22 always has the same node. In the case wherein region 26 does not overlap any wires in layout 21 , region 26 is shifted by minimum wire interval W 2 so that region 26 does not overlap the previous position in layout 21 and, then, the next region is selected and it is determined whether or not the selected region overlaps the wire layer of layout 21 . The determination is repeated (Step 2 A) until the scanning of the entire surface of the layout is completed or the next wire of the same node is found. [0104] The area of the selected wire 22 of the same node is calculated (Step 2 B). Contact hole 24 that overlaps the calculated wire 22 of the same node is selected (Step 2 C). At this time, wire 22 that has contact hole 24 and wire 23 that has contact hole 25 are of different nodes (FIG. 7D). The number of contact holes 24 that has been selected in step 2 C is calculated (Step 2 D). In the case wherein the number of contact holes 24 that has been calculated in step 2 D is equal to, or greater than, the limitation value that has been determined in advance according to the area of wires 22 of the same node, the area is detected as an error portion where wire formation defects occur (Step 2 E). [0105] Next, wires that have been selected in step 2 A are eliminated from input layout 21 (Step 2 F). The wires of the same node that have once been selected in step 2 F are eliminated from input layout 21 and are not selected again and, therefore, a high speed CAD process can be implemented. It is determined whether or not region 26 selected in step 2 A has scanned the entire surface of input layout 21 (Step 2 G). In the case wherein region 26 that has not been scanned exists, the procedure returns to step 2 A and is repeated. The inspection is completed after scanning the entire surface. [0106] [0106]FIG. 5 is a dataflow diagram showing a flow of data at the time of inspection according to the second embodiment of this invention. In the following the dataflow is described. [0107] As shown in FIG. 5, minimum wire interval region 26 is selected in same node wire recognition step 2 a and wire data 22 is selected and outputted as of the same node in the case wherein a region exists that overlaps wire data 22 of the inputted layout data 21 . The selected wire data 22 is inputted in same node area calculation step 2 b so as to calculate area and the calculation value is outputted. Input layout data 21 and wire data 22 that has been outputted in same node wire recognition step 2 a are inputted in contact recognition step 2 c so that contact hole data 24 in input layout data 21 that overlaps wire data 22 is selected and outputted. The number of pieces of contact hole data 24 that has been outputted in contact recognition step 2 c is calculated and outputted in contact number count step 2 d. [0108] The area of same node wire data 22 that has been outputted in area calculation step 2 b and the number of pieces of contact hole data 24 that has been outputted in contact number count step 2 d are inputted in error determination step 2 e and wire data 22 and contact hole data 24 that have been selected as errors are outputted in the case wherein the number of contact holes relative to the area does not satisfy the condition. Layout data 21 and wire data 22 are inputted in layout data update step 2 f wherein the layout data gained by subtracting selected wire data 22 from the wire layer of input layout data 21 is outputted so that this outputted data is used as the input layout data for wires that are inspected next. [0109] As a result of the above described procedure location where wire formation defects occur can be detected in the input layout. [0110] The third embodiment of this invention is described below in reference to FIGS. 8, 9, 10 A, 10 B, 10 C and 10 D. [0111] [0111]FIG. 9 is a flowchart showing the inspection algorithm according to the third embodiment of this invention and FIGS. 10A, 10B, 10 C and 10 D are diagrams showing the inspection process according to the third embodiment of this invention. In the following the inspection procedure is described in accordance with the flowchart. [0112] This semiconductor device layout inspection method is a method for inspecting formation defects that will occur in large area wires in a chip layout, wherein the number of contact holes in wires having a constant width is limited and the existence of defects is determined based on this number limitation and, thereby, wire formation defects are detected. [0113] In this case, as shown in FIGS. 10A and 10B, wires 32 having wire width that are equal to, or greater than, wire width L wherein the possibility of the existence of wire formation defects is considered to be high in layout 31 are selected (Step 3 A). As shown in FIGS. 10C and 10D, contact holes 33 that overlap wires 32 selected in step 3 A are selected (Step 3 B). The number of contact holes 33 that have been selected in step 3 B is calculated (Step 3 C). Error layout 34 is detected (Step 3 D) using the number limit (for example, four or greater) that has been set depending on wire width L. [0114] [0114]FIG. 8 is a dataflow diagram showing a flow data at the time of the inspection according to the third embodiment of this invention. In the following the dataflow is described. [0115] As shown in FIG. 8, wire width L that is considered to have a high possibility of wire formation defects is in advance defined in wire recognition step 3 a and wire data 32 of wires having a width that is equal to, or greater than, wire width L is selected from among the inputted layout data 31 so that the selected data is outputted. Wire data 32 that has been outputted in wire recognition step 3 a and input layout data 31 are inputted in contact recognition step 3 b and contact hole data 33 that overlaps wire data 32 is selected from input layout data 31 so that the selected data is outputted. Contact hole data 33 that has been outputted in contact recognition step 3 b is entered so that the number of contact holes is calculated and outputted in contact number counter step 3 c. [0116] The number of pieces of contact hole data 33 that has been outputted in contact number count step 3 c is inputted so as to output error layout data 34 corresponding to the number limit (for example, four or greater) that has been set depending on wire width L in error determination step 3 d. [0117] As a result of the above described procedure, locations wherein wire formation defects occur can be detected in the input layout. [0118] The fourth embodiment of this invention is described below in reference to FIGS. 11, 12, 13 A, 13 B, 13 C and 13 D. [0119] [0119]FIG. 12 is a flowchart showing an inspection algorithm according to the fourth embodiment of this invention and FIGS. 13A, 13B, 13 C and 13 D are diagrams showing the inspection process of the fourth embodiment of this invention. In the following the inspection procedure is described in accordance with the flowchart. [0120] This semiconductor device layout inspection method is a method for inspecting formation defects that will occur in large area wires in a chip layout, wherein the total area of the contact holes in wires of a constant width is limited and existence of defects is determined based on this area limitation and, thereby, wire formation defects are detected. [0121] In this case, as shown in FIGS. 13A and 13B, wires 42 having widths that are equal to, or greater than, wire width L2 and having a high possibility of occurrence of wire formation defects are selected in advance (Step 4 A). As shown in FIGS. 13C and 13D, contact holes 43 that overlap wires 42 selected in step 4 A are selected (Step 4 B). The areas of contact holes 43 selected in step 4 B are calculated (Step 4 C). Error layout 44 is detected using the area limitation that has been set depending on wire width L2 (Step 4 D). [0122] [0122]FIG. 11 is a dataflow diagram showing a flow of data at the time of the inspection according to the fourth embodiment of this invention. In the following the dataflow is described. [0123] As shown in FIG. 11, wire width L2 that is considered to have a high possibility of wire formation defects is in advance defined in wire recognition step 4 a wherein wire data 42 of wires having wire widths that are equal to, or greater than, wire width L2 is selected from the inputted layout data 41 so that the selected is outputted. Wire data 42 that has been outputted in wire recognition step 4 a and input layout data 41 are inputted in contact recognition step 4 b and contact hole data 43 that overlaps wire data 42 is selected from input layout data 41 so that the selected data is outputted. Contact hole data 43 that has been outputted in contact recognition step 4 b is inputted so as to calculate and output the total area of the contact holes in contact area calculation step 4 c. [0124] The total area of contact holes 43 that have been outputted in contact area calculation step 4 c is inputted and error layout data 44 , corresponding to the area limitation that is set depending on wire width L2, is outputted in error determination step 4 d. [0125] As a result of the above described procedure, locations wherein wire formation defects may occur in the input layout can be detected. [0126] The fifth embodiment of this invention is described below in reference to FIGS. 14, 15, 16 A, 16 B, 16 C, 16 D and 16 E. [0127] [0127]FIG. 15 is a flowchart showing the inspection algorithm according to the fifth embodiment of this invention and FIGS. 16A, 16B, 16 C, 16 D and 16 E are diagrams showing the inspection process according to the fifth embodiment of this invention. In the following the inspection procedure is described according to the flowchart. [0128] This semiconductor device layout inspection method is a method for inspecting formation defects that will occur in large area wires in the chip layout, comprising: the step of calculating the total area of wires of the same node and the total area of the contact hoes in the wires of the same node; and the step of determining the area limitation value of the contact holes in accordance with the total area of the wires of the same node, wherein the area of the same node is detected as wire formation defects when the total area of the contact holes is equal to, or greater than, the area limitation value. [0129] In this case, as shown in FIGS. 16A, 16B and 16 C, a region 56 with four sides having minimum wire interval W 3 is defined in layout 51 and wire 52 overlapped by region 56 is selected from among the wires in layout 51 . The selected wire 52 always becomes of the same node because region 56 has the minimum wire interval. In the case wherein region 56 does not overlap any wires in layout 51 , region 56 is shifted by minimum wire interval W 2 so as not to overlap the previous position in the layout and it is determined whether the selected next region overlaps the wire layer in layout 51 . The determination is repeated until the entire surface of the layout has been scanned or until the next wire of the same node is discovered (Step 5 A). [0130] The area of the selected wire 52 of the same node is calculated (Step 5 B). Wire 52 having a contact hole 54 and wire 53 having a contact hole 55 are of different nodes (FIG. 16D). Contact hole 54 that overlaps wire 52 selected in step 5 A is selected (Step 5 C). The total area of contact hole 54 selected in step 5 C is calculated (Step 5 D). A contact area limitation value X (μm 2 ) in accordance with the range of wire area B (μm 2 ) is uniquely determined from the area of wire 52 of the same node calculated in step 5 B using table 57 of FIG. 16E. In the case wherein the determined limitation area X (μm 2 ) and the total area of contact hole 54 calculated in step 5 D are compared so as to find that the total area is equal to, or greater than, the limitation value X (μm 2 ), the area is detected as an error wherein a wire formation defect has occurred (Step 5 E). [0131] Next, the wires selected in step 5 A are deleted from input layout 51 (Step 5 F). The wires of the same node that have once been selected in step 5 F are deleted from input layout 51 so as not to be selected again and, therefore, a high speed CAD process can be implemented. It is determined whether or not region 56 selected in step 5 A has scanned the entire surface of input layout 51 (Step 5 G). In the case wherein there is a region 56 that has not been scanned, the procedure returns to step 5 A so that the same steps are repeated. The inspection is completed as soon as the entire surface is scanned. [0132] [0132]FIG. 14 is a dataflow diagram showing a flow of data at the time of inspection according to the fifth embodiment of this invention. In the following the dataflow is described. [0133] As shown in FIG. 14, minimum wire interval region 56 is defined in step 5 a of recognizing wires of the same node and in the case wherein there is a region that overlaps wire data 52 of the inputted layout data 51 wire data 52 is selected and outputted as of the same node. Wire data 52 that has been recognized in step 5 a of recognizing wires of the same node is inputted in step 5 b of calculating wire areas so that the area is calculated and the result is outputted. The selected wire data 52 and layout data 51 are inputted in contact recognition step 5 c so that contact hole data 54 within layout data 51 that overlaps wire data 52 is selected and outputted. The selected contact hole data 54 is inputted in step 5 d of calculating contact areas so as to calculated the total area. The contact area limitation value X (μm 2 ) depending on wire area B (μm 2 ) of error condition table 57 that has been prescribed in advance by the occurrence ratio of wire defects and wire area B (μm 2 ) outputted in step 5 b of calculating wire areas are inputted in step 5 e of determining contact areas so that area limitation value X (μm 2 ) is uniquely determined. [0134] The limitation value X (μm 2 ) of the contact area outputted in contact area determination step 5 e and the contact area calculated in contact area calculation step 5 d are inputted in error determination step 5 f and, thereby, wire data 52 and contact hole data 54 that have been selected as errors in the case wherein the area is X (μm 2 ) or greater are outputted. Layout data 51 and wire data 52 are inputted in layout data updating step 5 g so as to output the layout data gained by subtracting selected wire data 52 from the wire layer of input layout data 51 is outputted and is used as input layout data of wires that are inspected next. [0135] According to the above described procedure portions where wire formation defects may occur can be detected in the input layout. [0136] The sixth embodiment of this invention is described below in reference to FIGS. 17, 18, 19 A, 19 B, 19 C, 19 D and 19 E. [0137] [0137]FIG. 18 is a flowchart showing an inspection algorithm of the sixth embodiment of this invention and FIGS. 19A, 19B, 19 C, 19 D and 19 E are diagrams showing the inspection process of the sixth embodiment of this invention. In the following, the inspection procedure is described according to the flowchart. [0138] This semiconductor device layout inspection method is a method for inspecting formation defects that occur in wires of a large area in a chip layout, which includes: the step of calculating the total area of wires of the same node and the number of contact holes in wires of the same node; and the step of determining the number limitation value of the contact holes in accordance with the total area of the wires of the same node, wherein wire formation defects are detected when the number of the contact holes is equal to, or greater than, the number limitation value. [0139] In this case, as shown in FIGS. 19A, 19B and 19 C, a region 66 having four sides of the minimum wire interval W 4 is defined in layout 61 and wire 62 overlapped by region 66 is selected from among wires in layout 61 . Region 66 has the minimum wire interval and, therefore, selected wire 62 always becomes of the same node. In the case wherein region 66 does not overlap any wires in layout 61 , region 66 is shifted by minimum wire interval W 4 so as not to overlap the previous position within the layout and it is determined whether or not the next selected region overlaps the wire layer of layout 61 . The determination is repeated until the entire surface of the layout has been scanned or until the next wire of the same node is discovered (Step 6 A). [0140] The area of the selected wire 62 of the same node is calculated (Step 6 B). Wire 62 having contact hole 64 and wire 63 having contact hole 65 are of different nodes (FIG. 19D). Contact holes 64 that overlap wire 62 selected in step 6 A are selected (Step 6 C). The number of contact holes 64 selected in step 6 C is calculated (Step 6 D). The contact number limitation value C in accordance with wire area B (μm 2 ) is uniquely determined from the area of wire 62 of the same node calculated in step 6 B using table 67 of FIG. 19E. The determined limitation number C and the number of contact holes 64 calculated in step 6 D are compared and in the case that the number is equal to, or greater than C, the area is detected as an error where wire formation defects may occur (Step 6 E). [0141] Next, the wires selected in step 6 A are deleted from the input layout (Step 6 F). The wires of the same node that have been once selected in step 6 F are deleted from the input layout so as not to be selected again and, therefore, a high speed CAD process can be implemented. It is determined whether or not region 66 selected in step 6 A has scanned the entire surface of the input layout (Step 6 G). In the case wherein there is a region 66 that has not been scanned, the procedure returns to step 6 A so that the steps are repeated. The inspection is completed when the entire surface is scanned. [0142] [0142]FIG. 17 is a dataflow diagram showing a flow of data at the time of inspection of the sixth embodiment of this invention. In the following, the dataflow is described. [0143] As shown in FIG. 17, the minimum wire interval region 66 is defined in step 6 a of recognizing wires of the same node and in the case wherein there is a region overlapped by wire data 62 of inputted layout data 61 , wire data 62 is selected and outputted as of the same node. The same node wire data 62 recognized in step 6 a of recognizing wires of the same node is inputted in step 6 b of calculating wire areas and the area is calculated and the result is outputted. The selected wire data 62 and layout data 61 are inputted in contact recognition step 6 c so as to select and output contact hole data 64 within layout data 61 that overlaps wire data 62 . The contact hole data 64 selected in contact recognition step 6 c is inputted in contact number counting step 6 d so as to calculate the number. Error condition table 67 that has been prescribed in advance by occurrence ratio of wire defects and wire area B (μm 2 ) outputted in wire area calculation step 6 b are inputted in contact number determination step 6 e wherein the contact number limitation value C depending on wire area B (μm 2 ) is determined and outputted. [0144] The limitation value C of the contact number outputted in contact number determination step 6 e and the contact number calculated in contact number counting step 6 d are inputted in error determination step 6 f , wherein wire data 62 selected and contact hole data 64 are outputted as errors in the case that the number is equal to, or greater than C. Layout data 61 and wire data 62 are inputted in layout data update step 6 g so that the layout data gained by subtracting selected wire data 62 from the wire layer of input layout data 61 is outputted and is used as input layout data of the next wire to be inspected. [0145] According to the above described procedure portions where wire formation defects will occur can be detected. [0146] The seventh embodiment of this invention is described below in reference to FIGS. 20, 21, 22 A, 22 B, 22 C, 22 D and 22 E. [0147] [0147]FIG. 21 is a flowchart showing the inspection algorithm according to the seventh embodiment of this invention and FIGS. 22A, 22B, 22 C, 22 D and 22 E are diagrams showing the inspection process according to the seventh embodiment of this invention. In the following, the inspection procedure is described according to the flowchart. [0148] This semiconductor device layout inspection method is a method for inspecting formation defects that will occur in wires of a large area in a chip layout, which includes: the step of calculating the number of contact holes in wires of a constant width; and the step of determining the number limitation value of the contact holes in accordance with the wire width, wherein the area is detected as a wire formation defect when the number of contact holes is equal to, or greater than, the number limitation value. [0149] In this case, as shown in FIGS. 22A and 22B, a wire 72 having a width greater than wire width L3, which is considered to have a high possibility of wire formation defects in layout 71 is selected in advance (Step 7 A). Contact holes 73 that overlap wire 72 selected in step 7 A are selected (Step 7 B). The number of contact holes selected in step 7 B is calculated (Step 7 C). The number limitation value of contact holes 73 calculated in step 7 C is uniquely determined by the contact number limitation value C (for example, range of L3=W→4 or more) depending on the range of wire width L3 in table 77 of FIG. 22E. As shown in FIGS. 22C and 22D, the determined limitation number 4 and the number of contact holes 74 that has been calculated in step 7 C are compared and the area is detected as an error portion wherein a wire formation defect may occur in the case wherein the number is equal to, or greater than, the limitation number (4) (Step 7 D). [0150] [0150]FIG. 20 is a dataflow diagram showing a flow of data at the time of inspection according to the seventh embodiment of this invention. In the following the dataflow is described. [0151] As shown in FIG. 20, in wire recognition step 7 a , wire width L3 that is considered to have a high possibility of a wire formation defect is defined in advance and wire data 72 having widths equal to, or greater than, wire width L3 is selected from inputted layout data 71 so as to be outputted. Wire data 72 that has been outputted in wire recognition step 7 a and input layout data 71 are inputted in contact recognition step 7 b so that contact hole data 73 that overlaps wire data 72 is selected from input layout data 71 so as to be outputted. Contact hole data 73 outputted in contact recognition step 7 b is inputted in contact number counting step 7 c so that the number is calculated and outputted. Error condition table 77 that has been prescribed in advance by the occurrence ratio of wire defects and wire width L3 (um) outputted in wire recognition step 7 a are inputted in contact number determination step 7 d so that the contact number limitation value C depending on wire width L3 (μm) is determined and outputted. [0152] The limitation value (for example, W1=4, or greater) of the contact number outputted in contact number determination step 7 d and the number of contact hole data 73 calculated in contact number counting step 7 c are inputted and are compared in error determination step 7 e so that contact hole data 74 selected is outputted as errors in the case of 4 or greater. [0153] According to the above described procedure, portions wherein wire formation defects may occur in the input layout can be detected. [0154] The eighth embodiment of this invention is described below in reference to FIGS. 23, 24, 25 A, 25 B, 25 C, 25 D and 25 E. [0155] [0155]FIG. 24 is a flowchart showing an inspection algorithm according to the eighth embodiment of this invention and FIGS. 25 A, 25 B, 25 C, 25 D and 25 E are diagrams showing an inspection process according to the eighth embodiment of this invention. In the following, the inspection procedure is described according to the flowchart. [0156] This semiconductor device layout inspection method is a method for inspecting formation defects that will occur in wires of a large area in a chip layout, which includes: the step of calculating the total area of the contact holes in a wire of a constant width; and the step of determining the area limitation value of the contact holes in accordance with the wire width, wherein the area is detected as a wire formation defect when the total area of the contact holes is equal to, or greater than, the area limitation value. [0157] In this case, as shown in FIGS. 25A and 25B, a wire 82 having a width equal to, or greater than wire width L4, which is considered to have a high possibility of a wire formation defect is in advance selected in layout 81 (Step 8 A). Contact holes 83 that overlap wire 82 selected in step 8 A is selected (Step 8 B). The total area of the contact holes selected in step 8 B is calculated (Step 8 C). The area limitation value of the contact holes calculated in step 8 C is uniquely determined by the contact area limitation value X (for example, range of W1→area of 1 μm 2 , or greater) that depends on the range of wire width L4 in table 87 of FIG. 25E. As shown in FIGS. 25C and 25D, the determined limitation area X (μm 2 ) and the area of contact holes 84 calculated in step 8 C are compared so that the area is detected as an error portion where a wire formation defect may occur in the case wherein the area becomes X (μm 2 ) or greater (Step 8 D). [0158] [0158]FIG. 23 is a dataflow diagram showing a flow of data at the time of inspection according to the eighth embodiment of this invention. In the following the dataflow is described. [0159] As shown in FIG. 23, wire data 82 of wires of which the width is wire width L4 or greater wherein the possibility of wire formation defects is considered to be had is in advance selected and outputted from layout data 81 in the wire recognition step 8 a . Wire data 82 outputted in wire recognition step 8 a and input layout data 81 are inputted in contact recognition step 8 b and contact hole data 83 that overlaps wire data 82 is selected and outputted from input layout data 81 . Contact hole data 83 outputted in contact recognition step 8 b is inputted in contact area calculation step 8 c so that the total area of contact hole data 83 is calculated and outputted. Error condition table 87 prescribed from the occurrence ratio of wire defects and wire width L4 (μm) outputted in wire recognition step 8 a are in advance inputted in contact area determination step 8 d so that the total contact hole area X (μm 2 ) depending on wire width L4 (μm) is uniquely determined and is outputted. [0160] The limitation value (for example, W1=1 μm 2 or greater) of the total contact area that have been outputted in contact area determination step 8 d and the total contact hole area that have been calculated in contact area calculation step 8 c are inputted and compared so that contact hole data 84 that has been selected as errors in the case wherein the area is 1 μm 2 or greater is outputted. [0161] According to the above described procedure, the portions where wire formation defects occur can be detected in the input layout. [0162] The ninth embodiment of this invention is described below in reference to FIGS. 26, 27, 28 A, 28 B, 28 C, 28 D, 29 A, 29 B, 29 C, 29 D, 29 E, 30 A, 30 B, 30 C, 30 D, 30 E and 30 F. [0163] [0163]FIGS. 28A, 28B, 28 C and 28 D are diagrams showing a region wherein the number of contact holes is collectively inspected according to the ninth embodiment of this invention. Region 96 shown by solid lines indicates the entire surface of the chip to be inspected. Regions 95 shown by dotted lines, respectively, have four sides with a predetermined inspection region width A and indicate inspection regions aligned in the longitudinal direction and in the lateral direction with equal intervals S. Symbols 91 to 94 indicate the shift conditions of the inspection regions. FIGS. 29A, 29B, 29 C, 29 D and 29 E show enlarged inspection regions of FIGS. 28A, 28B, 28 C and 28 D relative to wire layout 98 . [0164] [0164]FIG. 27 is a flowchart showing an inspection algorithm according to the ninth embodiment of this invention. In the following the inspection procedure is described according to the flowchart. [0165] This semiconductor device layout inspection method is a method for inspecting formation defects that will occur in wires of a large area in a chip layout, including the step of dividing the entire surface of the chip layout into a plurality of inspection regions; the step of limiting the number of contact holes in a wire of a constant width in the inspection regions; the step of inspecting wire formation defects by determining whether or not the area has a defect based on this number limitation; and the step of allowing the inspection regions to scan the entire surface of the chip layout. [0166] In this case, as shown in FIGS. 29A, 29B, 29 C, 29 D and 29 E, the total inspection region 95 is defined in input layout 98 , which is the inspection object. The inspection regions, respectively, have four sides with width A which are aligned in the longitudinal direction and in the lateral direction with equal intervals S (Step 9 A). In the following, the method for limiting the contact hole number utilizing the inspection regions is described. [0167] An inspection is carried out in inspection region 95 and when this inspection is completed inspection region 95 shifts within the layout to be inspected and an inspection of another region is again carried out. Inspection region 95 scans the entire surface and the inspection of the entire surface of the layout is completed. In the following one example where inspection region 95 shifts is cited and described. [0168] First, an inspection region is selected so as to be placed in the lower left of the entire surface of the layout (condition indicated by symbol 91 of FIG. 29A). When the inspection is completed in region 95 , inspection region 95 is then shifted by an interval that has in advance been determined by the data scale to be processed in the longitudinal direction 92 (FIG. 29B) The amount of shift of inspection region 95 and the size of one frame of inspection region 95 are varied depending on the data scale to be processed such that whether the entire inspection region is the entire surface of the chip or one block of the chip and, thereby, the inspection of the entire surface of the chip can be utilized in accordance with the purpose such that the process TAT is prioritized or a detailed inspection for a portion of the chip is prioritized. Such a shift in the longitudinal direction as indicated by symbol 92 is repeated until the inspection region has been shifted by S (interval of inspection region)+A (length of one side of the frame of the inspection region) from the initial position. Next, shifting is repeated until the inspection region has been shifted by S+A in the lateral direction as indicated by symbol 93 in the same manner as the above (FIG. 29C). Finally, shifting is repeated until the inspection region has been shifted in the diagonal direction indicated by symbol 94 in the same manner as the above (FIG. 29D). The inspection of the entire surface of the layout is completed at the point of time when shifting is completed in the three directions (Step 9 B). [0169] Next, a region 99 is selected wherein inspection region 95 and wire 97 within layout 98 overlap. As shown in FIGS. 30A and 30B, wire region 88 having wire width L5 which is considered to have a high possibility of wire formation defects is in advance selected from among the wire regions resulting from step 9 C (Step 9 C). As shown in FIG. 30C, a contact hole 89 that overlaps the wire selected in step 9 C is selected (Step 9 D). In the case wherein the contact hole selected at this time crosses inspection region 95 or in the case wherein the contact hole makes contact with the outside, the contact hole (symbol 107 shown in FIG. 30F) is not counted. The contact holes become count objects only in the case wherein the entirety thereof is included in inspection region 95 (symbol 106 shown in FIG. 30F). The number of selected contact holes 89 is calculated (Step 9 E). As shown in FIG. 30D, the area is detected as an error portion 90 where wire formation defects will occur in the case wherein the number of contact holes 89 calculated in step 9 E is compared with the predetermined error conditions so that the number of contact holes is equal to be the limitation value, or greater (Step 9 F). Next, it is determined whether or not inspection region 95 has scanned the entire surface of the chip (Step 9 G). In the case wherein the inspection region has not scanned the entirety of the chip steps 9 B to 9 G are repeated. In the case wherein the inspection region has scanned the entirety of the chip, the inspection is completed. [0170] [0170]FIG. 26 is a dataflow diagram showing a flow of data at the time of inspection according to the ninth embodiment of this invention. In the following the dataflow is described. [0171] As shown in FIG. 26, layout data 98 is inputted in inspection region selection step 9 a and correction inspection region data 95 in the layout to be inspected is defined so that wires that overlap layout data 98 are selected and outputted as specific region wire data 97 . In wire recognition step 9 b , wire data 88 having predetermined width L5 is selected and outputted specific region wire data 97 outputted in inspection region selection step 9 a . Specific region wire data 97 outputted in inspection region selection step 9 a and wire data 88 outputted in wire recognition step 9 b are inputted in contact recognition step 9 c and contact hole data 89 that overlaps wire data 88 is selected and is outputted from specific region wire data 97 . [0172] Contact hole data 89 outputted in contact recognition step 9 c is inputted in contact number counting step 9 d so that the number of contact holes is calculated. The number of contact holes outputted in contact number counting step 9 d and predetermined error conditions are compared in error determination step 9 e so as to output as an error contact hole data 90 selected in the case wherein the conditions are not satisfied. [0173] According to the above described procedure, the portions wherein wire formation defects occur can be detected in the input layout. [0174] The tenth embodiment of this invention is described below in reference to FIGS. 31, 32, 33 A, 33 B, 33 C, 33 D and 33 E. [0175] [0175]FIG. 32 is a flowchart showing an inspection algorithm of the tenth embodiment of this invention and FIGS. 33A, 33B, 33 C, 33 D and 33 E are diagrams showing the inspection process according to the tenth embodiment of this invention. In the following the inspection procedure is described according to the flowchart. [0176] According to this semiconductor device layout inspection method, the number of the contact holes in wires of a constant width is limited after wires of which the number of contact holes connected thereto is less than a constant number has in advance been removed from the chip layout in the third embodiment. [0177] In this case the minimum number (for example, three) of contact holes in a wire is defined as having a high possibility of defect occurrence. Next, as shown in FIGS. 33A and 33B, wires 102 having contact holes of which the number is equal to, or greater than, that defined in input layout 101 are selected and, thereby, wires which is not required to be inspected are deleted so as to shorten the CAD process TAT (Step 10 A). As shown in FIG. 33C, wires 103 having widths which are equal to, or greater than, predetermined wire width L6 are solely selected from layout 102 that has been filtered in step 10 A (Step 10 B). As shown in FIG. 33D, contact holes 104 that overlap wires 103 selected from layout 102 that has been filtered are selected (Step 10 C). As shown in FIG. 33E, the number of the selected contact holes is calculated (Step 10 D) and the predetermined error conditions and the number of contact holes that has been calculated in step 10 D are compared so that (three or more) contact holes 105 which do not satisfy the conditions are outputted (Step 10 E). [0178] [0178]FIG. 31 is a dataflow diagram showing a flow of data at the time of inspection according to the tenth embodiment of this invention. In the following the dataflow is described. [0179] As shown in FIG. 31, layout data 101 is inputted in wire filtering step 10 a and layout data 102 is outputted wherein the wires having no possibility of occurrence of wire formation defects are deleted due to the number of contact holes. Wire width L6 that is considered to have a high possibility of wire formation defects is in advance defined in wire recognition step 10 b and wire data 103 of wires having a width equal to, or greater than, wire width L6 is selected and outputted from inputted layout data 102 . Wire data 103 outputted in wire recognition step 10 b and layout data 102 are inputted in contact recognition step 10 c and contact hole data 104 that overlaps wire data 103 is selected and outputted from layout data 102 . [0180] Contact hole data 104 outputted in contact recognition step 10 c is inputted in contact number counting step 10 d so that the number is calculated and outputted. The number of the contact holes of contact hole data 104 outputted in contact number counting step 10 d is inputted in error determination step 10 e and contact hole data 105 is outputted that becomes an error corresponding to the number limitation (for example, four or greater) that has been set depending on wire width L6. [0181] According to the above described procedure, the portions where wire formation defects may occur can be detected in the input layout. [0182] The eleventh embodiment of this invention is described in reference to FIGS. 34, 35, 36 A, 36 B, 36 C, 36 D, 37 A, 37 B, 37 C, 37 D, 37 E, 38 A, 38 B, 38 C, 38 D, 39 A, 39 B, 39 C, 39 D and 39 E. [0183] [0183]FIGS. 36A, 36B, 36 C and 36 D are diagrams showing a region wherein the number of contact holes is collectively inspected according to the eleventh embodiment of this invention. A region 116 indicated by solid lines represents the entire surface of the chip to be inspected. Regions 115 indicated by dotted lines respectively have four sides of a predetermined inspection region width A2 and represent the inspection regions aligned in the longitudinal direction and in the lateral direction with equal intervals S 2 . Symbols 111 to 114 show the shift conditions of the inspection region. FIGS. 37A, 37B, 37 C, 37 D and 37 E show enlarged inspection regions of FIGS. 36A, 36B, 36 C and 36 D relative to wire layout 118 . [0184] [0184]FIG. 35 is a flowchart showing an inspection algorithm according to the eleventh embodiment of this invention. In the following the inspection procedure is described according to the flowchart. [0185] According to this semiconductor device layout inspection method, the inspection regions are limited to the inspection regions having contact holes of which the number is equal to, or greater than, a constant number from among a plurality of inspection regions and the number of contact holes is limited in wires having a constant width in the ninth embodiment. [0186] In this case, as shown in FIGS. 37A, 37B, 37 C, 37 D and 37 E, total inspection region 115 is defined in input layout 118 , which is an inspection object. The inspection regions respectively have four sides of width A2 and are aligned in the longitudinal direction and in the lateral direction with equal intervals S 2 (Step 11 A). In the following the contact hole limitation method using the inspection regions is described. [0187] An inspection is carried out in inspection region 115 and when the inspection is completed inspection region 115 is shifted within the layout to be inspected so that another region is inspected. When inspection region 115 scanned the entire surface the inspection of the entire surface of the layout is completed. In the following an example wherein inspection region 115 shifts is cited and explained. [0188] First, an inspection region is selected so that the region lines up with the lower left of the entire surface of the layout (condition of symbol 111 in FIG. 37A). When the inspection of inspection of section 115 integrated circuit completed, inspection region 115 is then shifted by a predetermined interval in the longitudinal direction 112 (FIG. 37B). The amount of shift inspection region 115 and the size of one frame of inspection region 115 are varied according to the data scale to be processed such that whether the entire inspection region is the entire surface of the chip or one block and thereby, an inspection can be used according to a purpose such that the inspection of the entire surface of the chip is carried out by prioritizing the process TAT and an inspection for a portion of the chip carried out by prioritizing the detail of the inspection. The shift in the longitudinal direction indicated by symbol 112 is repeated until the region is shifted by S 2 (interval between inspection regions)+A 2 (length of one side of the frame of an inspection region) from the original position. Next, the shift is repeated in the lateral direction as indicated by symbol 113 in the same manner, as the above until the inspection region is shifted by S 2 +A 2 (FIG. 37C). Finally, the shift is repeated in a diagonally direction as indicated by symbol 114 in the same manner as the above until the inspection region is shifted (FIG. 37D). The inspection of the entire surface of the layout is completed at the point in time when the shifts in the three directions are completed (Step 11 B). [0189] Region 115 selected in step 11 B is filtered using the number of contact holes. It is not necessary to inspect the regions having two or less contact holes in the case wherein a wire formation defect occurs when the number of contact holes is at least three irrelevant of the area and the width of the wires and therefore, an inspection region 120 wherein three or more contact holes exist is selected from inspection region 115 that has been selected in step 11 B as shown in FIGS. 38A, 38B, 38 C and 38 D (Step 11 C) and thereby the inspection process TAT can be shortened. [0190] Next a region 119 wherein the filtered inspection region 120 and wire 117 within layout 118 overlap is selected (Step 11 C). As shown in FIGS. 39A and 39B, a wire region 122 having a width that is equal to or greater than a predetermined width W is selected from among the wire region resulting from step 11 C (Step 1 D). As shown in FIG. 39C, a contact hole 123 that overlaps the wire selected in step 11 D is selected (Step 1 E). The number of the selected contacted holes 123 is calculated (Step 11 F). The number of contact holes 123 that has been calculated in step 11 F is compared with predetermined error conditions and the area is detected as an error portion where a wire formation defect may occur in the case wherein the number is equal to or greater than the limitation value (symbol 124 of FIG. 39D) (Step 11 G). Next, it is determined whether or not inspection region 115 has scanned the entire surface of the chip (Step 11 H). Steps 11 B to 11 G are repeated in the case wherein the entirety has not been scanned. The inspection is completed in the case wherein the entirety has been scanned. [0191] [0191]FIG. 34 is a dataflow diagram showing a flow of data at the time of inspection according to the eleventh embodiment of this invention. In the following, the dataflow is described. [0192] As show in FIG. 34, layout data 118 is inputted in inspection region selecting step 11 a and total inspection region data 115 is selected and outputted. Inspection region data 115 and layout data 118 are inputted in inspection region filtering step 11 b and a portion wherein inspection region 120 having three or more contact holes and wire 117 overlap is outputted as specific region wire data 119 from inspection region data 115 . Wire data 122 of wires having a predetermined width W is selected and outputted from specific region wire data 119 that is outputted from inspection region filtering step 11 b in wire recognition step 11 c . Specific region wire data 119 outputted in inspection region filtering step 11 b and wire data 122 outputted in wire recognition step 11 c are inputted in contact recognition step 11 d and contact hole data 123 that overlaps specific inspection wire data 119 is selected and outputted from specific inspection wire data 119 . [0193] Contact hole data 123 outputted in contact recognition step 11 d is inputted in contact number counting step 11 e so that the number of contact holes is calculated. The number of contact holes outputted in contact number counting step 11 e is compared with predetermined error conditions in error determination step 11 f so that contact hole data 124 selected is outputted as an error in the case wherein the conditions are not satisfied. [0194] According to the above described procedure, portions where wire formation defects will occur can be detected in the input layout. [0195] The twelfth embodiment of this invention is described below in reference to FIGS. 40, 41, 42 A, 42 B, 42 C, 42 D, 43 A, 43 B, 43 C and 43 D. [0196] [0196]FIGS. 42A, 42B, 42 C, and 42 D are diagrams showing an area where the number of contact holes is collectively inspected according to the twelfth embodiment of this invention. Region 136 indicated by solid lines represents the entire surface of the chip to be inspected. Regions 135 indicated by dotted lines have four sides respectively of a predetermined inspection region width A3 and represent inspection regions aligned in the longitudinal direction and the lateral direction with equal intervals S 3 . Symbols 131 to 134 show the shift conditions of the inspection regions. FIGS. 43A, 43B, 43 C and 43 D show enlarged inspection regions of FIGS. 42A, 42B, 42 C and 42 D relative to wire layout 138 . [0197] [0197]FIG. 41 is a flowchart showing an inspection algorithm according to the twelfth embodiment of this invention. In the following, the inspection procedure is described according to the flowchart. [0198] This semiconductor device layout inspection method is a method for inspecting the occurrence of formation defects in wires of a large area in the chip layout that includes the step of dividing the entire surface of the chip layout into a plurality of inspection regions; the step of limiting the area ratio of the total area of wires of the same node to the total area of the contact holes in the wires of the same node by using an antenna check in the inspection regions and of detecting wire formation detects by determining whether or not defects exist based on this limitation; and the step of allowing the inspection region to scan the entire surface of the chip layout. [0199] The above described antenna check is a technology of inspection by determining a threshold value based on the ratio of gates to the wires (vias, wires) in order to prevent the breakdown of a gate of a transistor due to a charge that occurs in the plasma etching step at the time of manufacturing a semiconductor device. [0200] In this case, a shown in FIGS. 43A, 43B, 43 C and 43 D, total inspection region 135 is defined in input layout 138 which is an inspection object. The inspection regions have four sides of width A3 respectively and are aligned in the longitude direction and in the lateral direction with equal intervals S 3 (Step 13 A). In the following, the method for limiting the area ratio of the total area of the same node to the total area of the contact holes using inspection region 135 is described. [0201] An inspection is carried out in inspection 135 and when the inspection is finished, inspection region 135 shifts within the layout to be inspected so that another inspection of a different region is carried out. When inspection region 135 scans the entire surface, the inspection of the entire surface of the layout is completed. In the following, an example wherein inspection region 135 is shifted is cited and described. [0202] First, an inspection region is selected so that the selected region is lined up with the lower left of the entire surface of the layout (condition of symbol 131 in FIG. 42A). When an inspection is completed in an inspection region 135 , inspection region 135 is then shifted by a predetermined interval in longitudinal direction 132 (FIG. 42B). The shift in the longitudinal direction indicated by symbol 132 is repeated until the region is shifted by S 3 (interval of inspection regions)+A 3 (length of one side of the frames of inspection regions) from the initial position. Next, the shift in the lateral direction indicated by symbol 133 is repeated in the same manner as the above until the inspection region is shifted by S 3 +A 3 (FIG. 42C). Finally, the shift in the diagonal direction indicated by symbol 134 is repeated in the same manner as the above until the inspection region is shifted (FIG. 42D). The inspection of the entire surface of the layout is completed at the point in time when the shifts in the three directions are completed (Step 13 B). [0203] Next, a wire 139 wherein inspection region 135 and wire 137 within layout 138 overlap is selected (Step 13 C). Contact hole 140 wherein inspection region 135 and a contact hole within layout 138 overlap is selected (Step 13 D). Wire 139 and contact hole 140 selected in step 13 C and step 13 D are used for an antenna check so that the ratio of the total area of the wires of the same node to the total area of the contact holes in the wires of the same node is calculated (Step 13 E). Though the ratio of the gate to the contact connected to the gate is calculated according to a conventional antenna check, it is possible to find a ratio of a wire to a contact hole connected to the wire by using wire 139 instead of the gate. The total area ratio calculated in step 13 E is compared with predetermined error conditions and is equal to be the limitation value or greater the area is detected as an error portion where a wire formation defect will occur (Step 13 F). Next, it is determined whether or not inspection region 135 has scanned the entire surface of the layout (Step 13 G). In the case wherein the entirety has not been scanned, steps 13 B to 13 G are repeated. In the case wherein the entirety has been scanned the inspection has been completed. [0204] [0204]FIG. 40 is a dataflow diagram showing a flow of data at the time of inspection according to the twelfth embodiment of this invention. In the following, the dataflow is described. [0205] As show in FIG. 40, layout data 138 is inputted in inspection region selecting step 13 a so that total inspection region data 135 is selected and outputted. Inspection region data 135 and layout data 138 are inputted in wire recognition step 13 b and wire data 139 that overlaps inspection region data 135 is selected from layout data 138 . Inspection region data 135 and layout data 138 are inputted in contact recognition step 13 c and contact hole data 140 that overlaps inspection region 135 is selected from the layout data. Wire data 139 selected in wire recognition step 13 b and contact hole data 140 selected in contact recognition step 13 c are inputted in area ratio calculating step 13 d so that wire data 139 is used in place of the gate and an antenna check is carried out. [0206] The area ratio outputted in area ratio calculating step 13 d is compared with predetermined error conditions in error determination step 13 e and wire data 139 and contact hole data 140 selected are outputted as errors in the case wherein the conditions are not satisfied. [0207] According to the above described procedure portions where wire formation defects may occur can be detected from the input layout. [0208] The thirteenth embodiment of this invention is described below in reference to FIGS. 44, 45, 46 A, 46 B, 46 C and 46 D. [0209] [0209]FIG. 45 is a flowchart showing an inspection algorithm according to the thirteenth embodiment of this invention. In the following, the inspection procedure is described according to the flowchart. [0210] This semiconductor device layout inspection method is a method for inspecting the occurrence of formation defects in wires of a large area in a chip layout that includes the step of defining a partial inspection region in a chip layout; the step of limiting the area ratio of the total area of wires of the same node to the total area of the contact holes in the wires of the same node by using an antenna check in the partial inspection region; the step of detecting wire formation defects by determining whether or not defects exists based on this limitation; and the step of allowing the partial inspection region to scan the entire surface of the chip layout by using a density check. [0211] The above described density check is the technology of inspection wherein a threshold value of a constant area ratio is determined in a single layer layout in order to increase the flatness and the etching precision in CMP (chemical mechanical polishing) at the time of manufacturing a semiconductor device. [0212] In this case, as shown in FIGS. 46A, 46B, 46 C and 46 D, a method is described wherein an area ratio calculation is carried out in partial inspection region 143 defined as having a size A 4 in input layout 142 , which is an inspection object, so that partial inspection region 143 scans the entire surface of layout 142 in shift step S 4 (<A 4 ) and, thereby, the total area ratio of the wires of the same node to the contact holes connected to the wires is limited. [0213] An inspection is carried out in partial region 143 and the inspection is completed partial inspection region 143 shifts within the layout to be inspected so that another inspection is carried out in a different region. When partial inspection region 143 scans the entire surface the inspection of the entire surface of the layout is completed (Step 14 A). A wire 145 where partial inspection region 143 and wire 141 within layout 142 overlap is selected (Step 14 B) a contact hole 146 wherein partial inspection region 143 and a contact hole within layout 142 overlap is selected (Step 14 C). Wire 145 and contact hole 146 selected in step 14 B and step 14 C are used for an antenna check so that the ratio of the total area of the wires of the same node to the total area of the contact holes in the wires of the same node is calculated (Step 14 B). Though the ratio of gates and contacts connected to the gates is calculated in a conventional antenna check, it is possible to find a ratio of wires to contact holes contacted to the wires by using wire 145 instead of the gate. In the case wherein, the total area ratio calculated in step 14 D is compared with predetermined error conditions so as to be found to be the limitation value or greater, the area is detected as an error portion wherein a wire formation defect will occur (Step 14 E). Next, it is determined whether or not partial inspection region 143 has scanned the entire surface of the layout (Step 14 F). In the case wherein the entirety has not been scanned, steps 14 A to 14 E are repeated. In the case wherein the entirety has been scanned, the inspection is completed. [0214] [0214]FIG. 44 is a dataflow diagram showing a flow of data at the time of inspection according to the thirteenth embodiment of this invention. In the following, the dataflow is described. [0215] As shown in FIG. 44, layout data 142 is inputted in partial inspection region selecting step 14 a so that partial inspection region data 143 is selected and outputted. Partial inspection region data 143 and layout data 142 are inputted in wire recognition step 14 b and wire data 145 that overlaps partial inspection region data 143 is selected from layout data 142 . Partial region inspection data 143 and layout 142 are inputted in contact recognition step 14 c and contact hole data 146 that overlaps partial inspection region data 143 is selected from layout data 142 . Wire 145 selected in wire recognition step 14 b and contact hole data 146 selected in contact recognition step 14 c are inputted in area ratio calculation step 14 d so that wire data 145 instead of the gate is used and an antenna check is carried out. [0216] The area ratio outputted in area ratio calculating step 14 d is compared with predetermined error conditions in error determination step 14 e so that wire data 145 and contact hold data 146 selected are outputted as errors in the case wherein the conditions are not satisfied. [0217] According to the above described procedure, portions where wire formation defects will occur can be detected in the input layout.

An object of the invention is to discover at the chip level a portion of a high density of contact holes in wires of a large area that becomes a portion where wire defects will occur. In order to achieve this, the area ratio of the total area of wires of the same node to the total area of contact holes in the wires of the same node is limited in a chip layout and wire formation defects are detected by determining whether or not defects exists based on this limitation. Thus, defects are detected wherein the area ratio exceeds the limit at the layout design stage and thereby formation defects such as a disconnection of a wire of a large area, a wire breakdown, a surface peeling due to a hillock or a defective connection between a wire and a contact hole can be avoided.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is in the field of computer hardware and specifically relates to a novel card edge conductor pattern and card edge connector that permits 114 conductors to be connected to the card, instead of the conductors used in the earlier 8-bit STD card. Cards of the new design can be used with connectors of the earlier type (although only 56 conductors will be connected to the card) and the new card edge connector will accept cards of the earlier standard design (although again only 56 conductors will be connected to the card). By use of the new card edge conductor pattern and card edge connector it is possible to build computers which have the capability of operating with 32-bit words but which also are compatible with earlier 8 and 16-bit STD cards. Conversely, the new card edge conductor pattern and card edge connector can be used in 8 and 16-bit computers to provide for later upgrading to 32 bits. 2. The Prior Art Brief acquaintance with the wiring diagrams of computers suggests that computers consist of processing circuits that are interconnected by a set of conductors. Some of the conductors are utilitarian and supply such housekeeping quantities as power and standard voltage levels including ground. Others of the conductors are bearers of reference quantities such as clock signals, timing signals, and signals that indicate the instantaneous state of the computer. Still others of the conductors carry signals representing data that is needed simultaneously in various parts of the computer. Together, these interconnecting conductors are called a bus. Instead of being mere conductors, the processing circuits operate on some of the signals they receive from the bus to produce other signals which they apply to the bus. Traditionally, the processing circuits have been developed and produced separately on individual printed circuit boards, also called cards. It is not difficult to visualize the bus as a sort of spinal cord of the computer and the processing circuits as the various bodily organs that are connected to it. This imagery leads understandably to a computer architecture in which a stack of spaced and parallel cards are distributed along a one-dimensional, usually linear, bus. The whole computer fits neatly into a rectangular box. Mechanically, one edge of each card fits into a socket in a card edge connector. The edge of the card includes a number of conductive fingers that are etched on the card and that extend perpendicular to the edge. Each conductive finger is contacted by a pin in the card edge connector, and is thereby connected electrically to a particular conductor in the bus. Normally the same pattern of conductive fingers is produced on both sides of the card adjacent the same edge, and the card edge connector includes a first set of pins that contacts the fingers on a first side of the card and a second set of pins that contacts the fingers on the second side of the card. At present more than 1000 different processing circuits are available in card form from various manufacturers, and these all have identically the same standard finger pattern known as the 8-bit STD pattern, shown in FIG. 1. The corresponding bus is called the 8-bit STD Bus. Introduced in 1978, the STD Bus is now the second most widely used industrial bus standard in the United States. An approved IEEE Standard, it provides a well-documented and supported modular approach for designing test and control systems. Rugged, easy to implement, and cost effective, STD Bus systems are being used at an increasing rate as this Standard enters its eleventh year. However, a demand is developing for higher performance systems that are more computation-intensive. These systems require a bus that can accommodate 32-bit words rather than the 8-bit words used with the 8-bit STD Bus. The present invention addresses the need for a 32-bit bus that retains the attractive characteristics of the 8-bit STD Bus and at the same time is backward-compatible with the more than 1000 8-bit STD cards currently available. Thus, the present invention, in providing a growth path from 8-bit to 32-bit data does more than merely add more fingers to the cards and pins to the card edge connectors, although these are necessary. The significant accomplishment of the present invention is to provide a 32-bit Bus that is compatible with the more than 1000 8-bit STD Bus cards currently available. This permits users of the 32-bit bus of the present invention to capitalize on the enormous variety of cards available in the 8-bit STD Bus format while keeping open a growth option to 32-bit performance. In U.S. Pat. No. 4,934,961 issued June 19, 1990 to Piorunneck, et al, there is described a bi-level connector for making mechanical and electrical contact between a mother printed circuit board and a daughter printed circuit board. The connector, as best seen in FIGS. 13 and 14 of the patent, uses alternating short and long contact pins which contact the daughter printed circuit board at different distances from its inserted edge. In contrast, in the present invention, the contact pins of the connector are identical. The connector of Piorunneck, et al. is described as having backward compatibility in the sense that their new connector will accommodate an older type of circuit board. However, their new type of circuit boards cannot be used in old type connectors; thus, unlike the present invention, the invention of Piorunneck, et. al. lacks forward compatibility. The patent includes a lengthy listing of the prior art. SUMMARY OF THE INVENTION The present invention includes a pattern of conductive fingers that make it possible to bring 114 conductors onto a printed circuit board (card) from a 32-bit bus. The pattern of conductive fingers permits the same card to be used with an 8-bit bus by inserting the edge of the card into an 8-bit edge connector. The present invention also includes a card edge connector that has 114 pins for use with the aforementioned circuit board, but arranged in a manner which permits the large number of previously developed 8-bit STD circuit boards to be used where appropriate in a computer using a 32-bit bus. In accordance with the present invention, a card edge connector is provided with two ranks of pins. The pins of the two ranks are interdigitated and electrically isolated from one another, but otherwise identical. Similarly, in accordance with the present invention the insertable edge of the card is provided with two ranks of etched conductive fingers. On both the card and the card edge connector, the pitch of the conductive fingers and of the pins, respectively, is half the pitch used in the prior art 8-bit cards and connectors, so that in the cards and connector of the present invention one rank of conductive fingers and pins is connected to the same bus conductors as they would be in the absence of the second rank. Thus, the cards and connectors of the present invention include all of the capabilities of existing 8-bit hardware. The provision of the second rank of pins and card fingers doubles the number of pins and fingers thereby enabling use of the cards and connectors in computers having a 32-bit bus, in the same space. The novel features which are believed to be characteristic of the invention, both as to organization and method of operation, together with further objects and advantages thereof, will be better understood from the following description considered in connection with the accompanying drawings in which a preferred embodiment of the invention is illustrated by way of example. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fractional plan view showing the pattern of conductive fingers adjacent the insertable edge of an 8-bit STD card of the prior art; FIG. 2 is a fractional cross sectional side elevation view showing an 8-bit STD card of the prior art inserted in a card edge connector of the prior art; FIG. 3 is a fractional cross sectional side elevation view showing in greater detail the 8-bit STD card of the prior art inserted in a card edge connector of the prior art; FIG. 4 is a fractional cross sectional side elevation view showing the 32-bit card of the present invention inserted in the card edge connector of the present invention; FIG. 5 is a diagram comparing the conductive finger pattern of the 32-bit card of the present invention (solid lines) with the conductive finger pattern of the 8-bit STD card of the prior art (dashed lines); FIG. 6 is a fractional plan view showing a first rank of conductive fingers on the 32-bit card of the present invention; FIG. 7 is a fractional plan view showing a second rank of conductive fingers on the 32-bit card of the present invention; FIG. 8 is a fractional plan view showing the first and second ranks of conductive fingers of FIGS. 6 and 7, respectively, as combined on the 32-bit card of the present invention; FIG. 9 is a diagrammatic perspective view showing an 8-bit STD card of the prior art inserted in a card edge connector of the prior art; FIG. 10 is a diagrammatic perspective view showing the 32-bit card of the present invention inserted in a card edge connector of the prior art to illustrate its compatibility therewith; FIG. 11 is a diagrammatic perspective view showing an 8-bit STD card of the prior art inserted in a card edge connector of the present invention to illustrate its compatibility therewith; and, FIG. 12 is a diagrammatic perspective view showing the 32-bit card of the present invention inserted in a card edge connector of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with the help of the figures, in which the same reference numeral is used to denote the same part throughout. FIG. 1 shows a face of an 8-bit STD card 2 of a type well known in the prior art. The success of the 8-bit STD card design is attested to by its widespread use throughout the computer industry and by the fact that more than 1,000 circuits are available commercially on such cards. In use, the edge 3 is inserted in the direction of the arrow 4 into an edge connector 6 as shown in FIG. 2. The edge 3 includes 28 conductive fingers, of which the conductive finger 5 is typical, juxtaposed along the edge 3 on both faces of the card. FIG. 2 shows the 8-bit STD card 2 inserted into the 8-bit edge connector 6. The latter includes a base 8 and two rows of pins, of which the pin 7 is typical, which extend from the base 8 to make electrical contact with the conductive fingers 5. FIG. 3 is an enlarged detail of FIG. 2 and shows that the pin 7 makes contact with the conductive finger 5 on the card 2 a distance d 0 from the edge 3 when the card is fully inserted into the connector. The elements shown in FIG. 3 are shown in a perspective view in FIG. 9. The 32-bit card 10 of the present invention has the same exterior dimensions as the 8-bit STD card of the prior art and plugs into the 32-bit card edge connector 12 of the present invention as shown in FIG. 4, in a manner similar to that in which the 8-bit STD card 2 of the prior art plugs into the 8-bit card edge connector 6 of the prior art. That is, the edge 14 of the card 10 extends into the base 18. Pins, of which the pin 16 is typical, extend from the base 18 and contact the conductive fingers 20 and 22 on the card 10 at a distance d 1 from the inserted edge 14. The assembly of FIG. 4 is shown in a perspective view in the diagram of FIG. 12. FIG. 5 is a diagram showing on an enlarged scale the conductive fingers of the 32-bit card 10 adjacent its edge 14. In FIG. 5, the conductive fingers 5 of the 8-bit STD card of FIG. 1 are shown by dashed lines for comparison. In FIG. 5, the contact areas of the pins 7 with the conductive fingers 5 of the 8-bit STD card are denoted by the letters P 1 and P 2 . Likewise, the contact areas of the pins 16 of the 32-bit card edge connector 12 of the present invention on the conductive fingers of the 32-bit card 10 of the present invention are denoted by the letters E 1 through E 4 . Note that the ample length of the conductive fingers 5 easily accommodates the greater length of the pins 16 of the 32-bit card edge connector of the present invention. This may be seen more clearly in the perspective view diagram of FIG. 11. The conductive fingers 20 constitute a first set or rank of conductive fingers on the 32-bit card, and as seen in FIG. 5, the conductive fingers 20 are spaced at a pitch of 2K. In accordance with the preferred embodiment of the present invention, a second set or rank of conductive fingers 22 is produced along the edge 14 of the 32-bit card 10. This second set of conductive fingers 22 includes the contact areas E 2 and E 4 . The conductive fingers 22 are electrically isolated from each other as well as from the conductive fingers 20. FIG. 6 shows the first set of conductive fingers 20 spaced along the edge 14 of the 32-bit card 10 of the present invention. In addition to the first set of conductive fingers 20, a plus 5V conductive finger 24 and a GROUND conductive finger 26 are provided to receive power from the bus. Because of the possibility that greater power will be flowing through these fingers 24, 26, they are made wider to lower their resistance and to dissipate ohmic heat. They are formed by combining one conductive finger of the type 20 with one finger of the type 22. FIG. 7 shows a second set of conductive fingers composed of the fingers 22. The pattern of conductive fingers shown in FIG. 6 and the pattern of conductive fingers shown in FIG. 7 would not likely be used separately, but they are shown separately for purposes of illustration. In accordance with the preferred embodiment of the present invention, the two sets of conductive fingers are combined on a card 10 as shown in FIG. 8. Thus, the present invention replaces the set of fingers 5 shown in FIG. 1 with the two sets of conductive fingers combined in the manner shown in FIG. 8. As pointed out above in connection with FIGS. 3 and 4, the present invention also necessitates increasing the length of the pins of the card edge connector and decreasing the width of the pins. The card 2 of FIG. 1 has 28 fingers on each face along the same edge, making a total of 56 fingers per card. The pattern shown in FIG. 8 is duplicated on the other face of the card, so that the card includes 52 fingers like the finger 20, and 54 fingers like the finger 22 plus 4 power fingers 24 and 26 as illustrated in FIG. 5 consisting of 4 fingers 20 and 4 fingers 22 for a grand total of 114 fingers. In the best mode of using the circuit card of the present invention, the same physical quantities that were assigned to the fingers 5 of the card 2 of the prior art are assigned in exactly the same order to the conductive fingers 20 of the first set. In this way, circuits that have been developed for use on the cards 2 of the prior art can be inserted into the card edge connector of the present invention, and the electrical signals will be delivered to the appropriate pin of the connector. That is to say, the 8-bit cards of the prior art are electrically compatible with the 32-bit card edge connector of the present invention. Electrical contact is made at the odd-numbered contact points E 1 , E 3 , E 5 ... on conductive fingers 5 as shown in FIG. 5. This is further illustrated in FIG. 11, wherein every other one of the pins 16 does not contact a conductive finger and is therefore unused. This feature is sometimes referred to as backward compatibility meaning that the card edge connector of the present invention is compatible with the prior art cards 2. This should be distinguished from what is sometimes called forward compatibility, illustrated in FIG. 10, in which the card edge connectors 6 of the prior art are electrically compatible with the cards 10 of the present invention. Electrical contact is made at contact point P i on conductive fingers 20. This arrangement provides for possible expansion of the capabilities of the cards by later inclusion of circuitry connected to the fingers 22. Maximum capability is achieved when the 32-bit cards of the present invention are used with the 32-card edge connector of the present invention, as illustrated in FIG. 12. This arrangement permits the full flexibility and power of 32-bit circuitry to be employed in a manner familiar to designers from their experience with the 8-bit technology. Thus, it is seen that the present invention is more subtle than merely including more conductive fingers by making them smaller. While that is necessary, the present invention is configured in a manner that provides both forward and backward compatibility which is of enormous commercial and industrial importance. The foregoing detailed description is illustrative of one embodiment of the invention, and it is to be understood that additional embodiments thereof will be obvious to those skilled in the art. The embodiments described herein together with those additional embodiments are considered to be within the scope of the invention.

A printed circuit card and card edge connector for use with a 32-bit bus include respectively a pattern of conductive fingers and pins in the connector that render the card electrically compatible with existing 8-bit STD connectors and that render the card edge connector electrically compatible with existing 8-bit STD cards. the latter compatibility makes it possible to use in 32-bit systems any of the more than a thousand existing 8-bit circuits without modification; while the former compatibility makes available to 8-bit systems an easy path to growth and the expanded computational power of a 32-bit system.

This is a continuation of prior filed U.S. patent application Ser. No. 08/317,294, filed Oct. 3, 1994, now U.S. Pat. No. 5,594,710, which is a continuation-in-part of prior filed U.S. patent application Ser. No. 08/253,887, filed Jun. 3, 1994, still pending. BACKGROUND OF THE INVENTION The present invention relates to a disc player having a magazine for holding a plurality of discs, and which is capable of continuous playback of discs from the magazine. In particular, the disc player of the present invention has a magazine with a securing mechanism for preventing displacement of discs within the magazine due to vibration or inclination of the disc player. The preferred embodiment of the device disclosed in the parent application, copending herewith, includes a disc player in which a security device prevents vibrations from moving discs within a magazine. In that device, upper and lower disc-lock shafts engage disc spindle holes and the carriages which support each disc. A closable gap between the upper and lower disc-lock shafts is used, when opened, to pass a single disc from the magazine into playback and eject positions. A drawback of the above is that the mechanism which closes the gap between the upper and lower disc-lock shafts only does so during the eject mode of operation. This created a difficulty in that the security mechanism ineffective during playback and stop modes. A further drawback of the above is that the first carriage, located at the lower end of the magazine, has a first 12 cm diameter cavity and a second 8 cm cavity for mounting large and small discs, respectively. When the first carriage is disposed in the gap between the upper and lower disc-lock shafts, the shafts do not pierce effectively the spindle hole in the disc. This is not a problem with a 12 cm in the carriage, since the depression in the carriage, together with the underside of the next-higher carriage, prevents unwanted motion of the 12 cm disc. With an 8 cm disc in the second 8 cm cavity in the carriage, vibration or incline of the device could dislodge the disc from the 8 cm cavity into the 12 cm cavity. In some cases this can jam the disc player components and damage the disc. OBJECTS AND SUMMARY OF THE INVENTION It is accordingly an object of the present invention to provide a changer-type disc playback device which overcomes the drawbacks of the prior art. It is a further object of the present invention to provide a security mechanism to prevent discs stored within a magazine from unwanted motion due to the effects of vibrations or inclines during all modes of operation of the disc player. It is still a further object of the present invention to provide a disc playback device which returns its magazine to a position of rest, engaging the security mechanism, during its stop mode to ensure that 8 cm discs are properly secured within the security mechanism. Briefly states, a disc player has a magazine for storing discs and a disc transport mechanism transporting a selected disc between a playback position outside the magazine and a store position located entirely within the magazine. The carriages are stacked upon each other and pivotally supported within the magazine. The carriages are extracted from the stack by lifting a front end of a carriage above a selected carriage. Subsequent to the lifting of the carriage, the selected carriage is withdrawn from the magazine to the playback position. When a selected carriage is moved to the playback position, the discs on carriages above and below the selected carriage are prevented from shifting with the removal of the selected carriage by coaxial opposing shafts which extend through spindle holes in the discs on the carriages above and below the selected disc. A closeable gap between the two shafts permits the selected disc to be shifted. The gap is closed, except when a carriage is being shifted into or out of the magazine, thereby preventing discs and their carriages from shifting due to vibration or tilting of the cabinet. When the device is in a stop mode, the magazine shifts to pierce any carriages capable of holding discs of different sizes, thereby preventing smaller disc from moving into recesses for larger discs. According to a preferred embodiment of the invention, there is provided a disc player for storing discs, each having a spindle hole, and playing a selected disc of the discs, comprising a magazine having a plurality of means for holding a disc, a playback position, means for reading said selected disc, of said discs, in said playback position, means for transporting said a selected disc between said playback position and a store position in said magazine, a first shaft extending into said magazine, through said spindle hole of at least one of said discs in said magazine and having an end in said magazine at a first position, a second shaft extending into said magazine, coaxially aligned with and opposing said first shaft, said second shaft extending through said spindle hole of at least another of said discs held in said magazine and having an end in said magazine at a second position, said first and second positions defining a gap, aligned in a common plane with said playback position, allowing said selected disc to be transported between said store position in said magazine and said playback position, and means, responsive to said each of discs in said magazine, for moving said magazine to a predetermined position. According to a feature of the invention, there is provided a disc player for storing discs, each having a spindle hole, and playing a selected disc of the discs, comprising a magazine having means for storing said discs, a playback position, means for reading said selected disc, of said discs, when said selected disc is moved to said playback position, means for transporting said selected disc between said playback position and a store position within said magazine, a first shaft extending into said magazine, through said spindle hole of at least one of said discs held in said magazine and having an end in said magazine at a first position, a second shaft extending into said magazine coaxially aligned with and opposing said first shaft, means for slidably mounting said second shaft, said second shaft extending through said spindle hole of at least another of said discs held in said magazine and having an end in said magazine at a second position, said first and second positions defining a gap, aligned in a common plane with said playback position, allowing said selected disc to be transported between said store position in said magazine and said playback position, locking means for shifting said second shaft in an axial direction to a lock position, closing said gap, thereby securing said discs in said magazine by extensions of each of said first and second shafts through spindle holes of said discs, said locking means including means for biasing said second shaft toward said first shaft and means for displacing said second shaft, in a direction opposing said means for biasing, a distance effective for permitting only said selected disc to pass therebetween, and means for moving, responsive to each of said discs being in said magazine, said magazine to a predetermined position such that one of said first and second shafts pierce said spindle hole of selected ones of said discs. According to a further feature of the invention, there is provided a magazine for storing discs, each having a spindle hole, comprising means for holding said discs in a concentric array with said spindle holes aligned, a shaft extending through said spindle holes of said discs to secure said discs in said magazine, means for slidably mounting said shaft, means for retracting said shaft, at least partially from said magazine, to allow withdrawal or insertion of a single disc at a time in said magazine, and means, responsive to said discs being in said magazine, to move said means for holding discs such that said shaft pierces predetermined ones of said discs through said spindle holes. According to a still further embodiment of the invention, there is provided a disc playback device, comprising a magazine, said magazine including at least one means for holding a disc of a first size, said magazine including at least one means for holding a disc of a second size, a playback position, each of said discs in said magazine having a store position disposed substantially in a plane defined by said playback position, a first shaft, extending downward from a top portion of said magazine, extending through said spindle holes of said discs disposed in said magazine above said plane to secure said discs in said magazine, a second shaft, extending downward from a bottom portion of said magazine, extending through said spindle holes of said discs disposed in said magazine below said plane to secure said discs in said magazine, retracting means for shifting said second shaft axially to lock with said first shaft to secure all discs in said magazine, means, responsive to a stop mode of operation, for moving said magazine to a rest position where one of said first and second shafts pierce said at least one means for holding a disc of a second size. The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with accompanying drawings, in which like reference numerals designate the same elements. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-section perspective drawing of the present disc playback device in a stop mode, in which the magazine is in a first position. Pos(1). FIG. 2 is a cross-section perspective drawing of the present disc playback device in a stop mode, in which the magazine is in a fourth position, Pos(4). FIG. 3 is a cross-section perspective drawing of the present disc playback device in a center position. FIG. 4 is a cross-section perspective drawing of the present disc playback device in a center position in which a disc is clamped. FIG. 5 is a cross-section perspective drawing of the present disc playback device in an eject position. FIG. 6 is a drawing indicating the positional relationship between cam 260 and switches 312-314 at cam angle of +22.5°. FIG. 7 is a drawing indicating the positional relationship between cam 260 and switches 312-314 at cam angle of -112.5°. FIG. 8 is a drawing indicating the positional relationship between cam 260 and switches 312-314 at cam angle of -202.5°. FIG. 9 is a timing chart indicating a relationship between optical mechanism 200, lower disc-lock shaft 251, and cam angle of cam member 110. FIG. 10 is a block diagram indicating the control circuit for the present disc playback device. FIG. 11 is a timing chart indicating changes in a D.CNT signal and the H.POS signal relative to the position of the magazine. FIG. 12 is a flowchart showing the MAIN routine for system controller 300. FIG. 13 is a flowchart showing the JOB EJECT routine. FIG. 14 is a flowchart showing the JOB EJECT routine. FIG. 15 is a flowchart showing the JOB EJECT routine. FIG. 16 is a flowchart showing the JOB PLAY routine. FIG. 17 is a flowchart showing the JOB PLAY routine. FIG. 18 is a flowchart showing the JOB STOP routine. FIG. 19 is a flowchart showing the JOB DISC routine. FIG. 20 is a flowchart showing the JOB DISC routine. FIG. 21 is a flowchart showing the JOB DISC routine. FIG. 22 is a flowchart showing the JOB NEXT routine. FIG. 23 is a timing chart TC2 used in describing a portion of the steps found in the flowcharts in FIGS. 13, 16 and 19. FIG. 24 is a timing chart TC4 used in describing a portion of the steps found in the flowchart in FIG. 14. FIG. 25 is a timing chart TC3 used in describing a portion of the steps found in the flowchart in FIG. 15. FIG. 26 is a timing chart TC5 used in describing a portion of the steps found in the flowchart in FIG. 16. FIG. 27 is a timing chart TC6 used in describing a portion of the steps found in the flowcharts in FIGS. 17, 21 and 22. FIG. 28 is a timing chart TC7 used in describing a portion of the steps found in the flowcharts in FIGS. 17 and 21. FIG. 29 is a timing chart TC8 used in describing a portion of the steps found in the flowcharts in FIGS. 18, 20 and 22. FIG. 30 is a sample display for display 329. FIG. 31 is another sample display for display 329. FIG. 32 is still another display for display 329. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 5, a disc playback device, shown generally at 1000, includes a magazine 50 which holds seven carriages 51-57 for carrying discs. Each carriage 51-57 has a 12 cm diameter first recess 162 for receiving individual compact discs. First carriage 51, located in the lowest level of magazine 50, also has an 8 cm diameter second recess 166 for smaller discs. The seven carriages 51-57 are stacked in contact with each other in the magazine 50. Referring now to FIGS. 1 and 2, a vertical transport mechanism 318 moves magazine 50 vertically to align in a selected one of seven positions, Pos(1)-Pos(7), corresponding to the locations of the seven carriages 51-57 with a store position. The store position is a position of a disc, or carriage, in magazine 50 which is in planar alignment with a playback position above a turntable 202. Once a carriage is aligned with the store position, a tray/carriage transport mechanism 309 can transport the carriage to the playback position for playing. The carriage so moved is known as the selected carriage. In FIG. 1, magazine 50 is shown in position Pos(1), where first carriage 51 is the selected carriage. In FIG. 2, magazine 50 is shown in position Pos(4), where fourth carriage 54 is the selected carriage. Similarly, a position exists for each of the remaining carriages in magazine 50 corresponding to the store position for each disc. Referring now to FIGS. 1 and 3, first carriage 51 in Pos(1) is transported from magazine 50 by a tray/carriage transfer mechanism 309 to a playback position. To play a disc 1 on selected first carriage 51, an optical mechanism 200 moves upward at the playback position. The motion of optical mechanism 200 clamps disc 1 between turntable 202 and a magnetic clamper 190 and moves an optical head 203 into an operational position. Playback is then performed in a conventional manner. As first carriage 51 is moved from the store position to the playback position, a carriage lifter (not shown) engages a wedge-shaped portion at a front edge of second carriage 52, located immediately above and adjacent first carriage 51. Third through sixth carriages 53 through 57 are stacked consecutively atop second carriage 52. The carriage lifter lifts the front edges of second through seventh carriages 52-57, permitting selected first carriage 51 to dismount smoothly from the stack of adjacent carriages within magazine 50. Lifting second carriage 52 provides a space between disc 1 and an overlapping disc on second carriage 52 when first carriage 51 is in the playback position. The space also provides sufficient clearance for magnetic clamper 190 to clamp disc 1. A front edge of a top panel 30, above magazine 50, movably supports magnetic clamper 190. Although FIG. 3 illustrates movement of the lowest first carriage 51, a similar operation applies for any selected carriage. In second through seventh carriages 52-57, however, the carriage lifter simultaneously applies upward force on carriages above, and downward force on carriages below the selected carriage, thereby raising the upper carriages and preventing lower carriages from dislodging when the selected carriage is withdrawn from magazine 50. Referring now also to FIG. 5, from the playback position, selected first carriage 51 moves to a load position (not shown) from which it is inserted into a tray 20 (the operations discussed herein apply to any of first through seventh carriages 51-57). Tray/carriage transport mechanism 309 moves tray 20 from the load position to an eject position. In the eject position, the user can remove and replace disc 1 in selected carriage 51. Tray 20 also returns selected carriage 51 to the load position, from which it can move to the playback position or the store position. After selected first carriage 51 is inserted into tray 20, selected first carriage 51 locks to tray 20 during transport from the load position to the eject position. Selected first carriage 51 disengages from tray/carriage transport mechanism 309 when first carriage 51 locks into tray 20. Referring now to FIGS. 1-5, an upper disc-lock shaft 250 extends from a lower surface of top panel 30, projecting through both spindle holes 163 of discs 1 stored within magazine 50 and slots 163a of each carriage, which concentrically align with spindle holes 163. A lower end of upper disc-lock shaft 250 projects through slot 163a of the carriage immediately above the selected carriage. For example, in FIG. 2, the lower end of upper disc-lock shaft 250 projects through slot 163a of fifth carriage 54, immediately adjacent and above the selected fourth carriage 54. This prevents discs in the carriages above the selected carriage from moving due to shocks or inclines. Referring now to FIGS. 4 and 5, a support base 252 movably supports a lower disc-lock shaft 251 coaxially opposing upper disc-lock shaft 250. Support base 252 permits lower disc-lock shaft 251 to move vertically as follows. A spring 253, disposed within lower disc-lock shaft 251, applies an upward bias to lower disc-lock shaft 251. A control arm 254 is pivotally mounted on support base 252 by a shaft 255. A follower pin 256 extends from an end of control arm 254 to engage a cam groove 101 in an outer surface of a cam member 110. A cam member drive mechanism 319 drives cam member 110. Cam groove 101 wraps around cam member 110 in a spiral fashion (most of which is not visible from the vantage point of FIGS. 1-5). A yoke 257, extending from another end of control arm 254, engages an upper surface of a pin 258 projecting from lower disc-lock shaft 251. Rotation of cam member 110 pivots control arm 254, thereby raising and lowering lower disc-lock shaft 251 between a lock position, in which it engages upper disc-lock shaft 250, and an unlock position, in which its upper end retracts below the selected carriage. Thus, lower disc-lock shaft 251 alternately passes through, and out of, spindle hole 163 of the disc on the selected carriage as lower disc-lock shaft 251 moves up and down, respectively. Optical mechanism 200, positioned below tray 20, is pivotally supported by a pine 204. Pin 204 is horizontally mounted to permit optical mechanism 200 to move in a substantially vertical direction. Optical mechanism 200 includes a base frame 180 from which another pin (hidden behind base frame 180) engages cam groove 101. As a result, rotation of cam member 110 moves optical mechanism 200 vertically. Optical mechanism 200 moves between an upper position and a lower position. In the upper position, optical mechanism 200 aligns with disc 1 in the playback position. In the lower position, optical mechanism 200 moves below the plane formed by disc 1, thereby freeing the path for transferring selected first carriage 51 into and out of tray 20. A cam 260, integrally formed on lower portion of cam member 110, engages switches 312-314 that indicate different states of the disc playback device as described below. Referring now to FIGS. 6-9, cam 260 rotates with cam member 110 to sequentially actuates switches 312-314. Switches 312-314 are precisely positioned at separate locations on a lower surface of a main chassis of the disc playback device 1000. Actuation of switches 312-314 generate signals POS 1-3 (shown in FIG. 9), respectively, which are sent to a system controller 300 (FIG. 10). A rotational angle of zero for cam 260 is defined as the angle at which rotation of cam 260 lifts optical mechanism 200 into its upper position. Cam groove 101 has a spiral shape so that optical mechanism 200 is advanced when cam member 110 rotates through angles of 0°--90°. However, there are also non-advancing portions of cam groove 101 where the optical mechanism remains stationary while cam member 101 rotates through angle ranges of +22.5° to 0°, and -90° to -202.5°. Referring now to FIGS. 6 and 9, angles of rotation of cam 260 between zero and +22.5°, otherwise known as the UP range, maintains optical mechanism 200 in the upper position and lower disc-lock shaft 251 in the lock position. Switches 312-314 are all turned on, rendering signals POS 1-3 all at a state identified in FIG. 9 as "L" (hereinafter "H" and "L" represent high and low signal level states respectively). When cam 260 rotates from a cam angle of zero to -90°, optical mechanism 200 moves from its upper to lower position, while lower disc-lock shaft 251 similarly descends from its lock position to an unlock position. During this time, switch 312 is off, and POS 1 signal is "H". Referring now to FIGS. 7 and 9, at rotational angles between -90° and -135°, otherwise known as the DOWN range, cam 260 turns switches 312 and 313 off, and POS 1 and POS 2 signals are "H". Optical mechanism 200 stays in its lower position while lower disc-lock shaft 251 stays in the unlock position. Referring now to FIGS. 8 and 9, rotation of cam 260 negatively past -135° turns switch 314 off, rendering all of POS signals 1-3 signal to "H". During this interval, lower disc-lock shaft 251 rises, returning to the lock position when cam member 110 reaches the -180° position. When cam 260 rotates negatively past the -180° point, switch 312 turns on, and signal POS 1 changes to "L". While cam 260 is within the range -180° to -202.5°, otherwise known as the LOCK range, optical mechanism 200 remains in the down position while lower disc-lock shaft 251 remains in the lock position. Referring now to FIG. 10, a control circuit 1010 includes a system controller 300 optionally having a read-only memory, a random-access memory, and interface circuitry. System controller 300 may also incorporate one or more microprocessors. System controller 300 controls disc playback device 1000 according to an operating mode set by user input through a mode control panel 301. A backup power supply 302 connects to system controller 300, allowing its random-access memory to retain data when the power supply is turned off or otherwise interrupted. Limit switches 303-305 apply high "H" and low "L" signal levels to STORE, T.CLOSE, and EJECT inputs of system controller 300, respectively. A "L" signal level at these inputs indicates that tray/carriage transport mechanism 309 has moved the selected carriage to the store, load, and eject positions, respectively. A photo-interrupter 306 detects that tray/carriage transport mechanism 309 has moved the selected carriage to the playback position by applying a signal at a CENTER input of system controller 300. System controller 300 applies control signals to a motor drive circuit 307 via a FRONT output and a REAR output. A tray motor 308 rotates in forward and reverse directions according to output from motor drive circuit 307. Tray motor 308 drives tray/carriage transport mechanism 309. According to the preferred embodiment of the invention, tray 20 moves toward the front (toward the eject position) of disc playback device 1000 when an "H" signal level is applied by the FRONT output. Tray 200 moves to the rear (toward the store position) of disc playback device 1000 when an "H" signal level is applied by the REAR output. An the "H" level applied simultaneously by both FRONT and REAR outputs shorts the outputs of motor drive circuit 307, causing a magnetic braking effect in tray motor 308. When both outputs are held at the "L" level, the outputs of motor drive circuit 307 are open. System controller 300 has several additional inputs for receiving input signals. A D.CNT input, connected to a photo-interrupter 310, receives an input signal indicating the position of magazine 50. An H.POS input, connected to a limit switch 311, receives an input signal that detects a reference position of magazine 50. Inputs POS 1-3 are connected to switches 312-314. Inputs POS 1-3 receive signals that indicate the position of cam 260, as described above. FIG. 11 shows the changes in D.CNT signal and H.POS signal corresponding to the position of magazine 50. The D.CNT signal outputs a brief "L" each time magazine 50 brings a disc into its respective position Pos(n) (where n is the disc number). The H.POS input normally remains at "H", except when magazine 50 is roughly midway between Pos(1) and Pos(2), at which point H-POS becomes a "L". Simultaneous reception of a "L" at both the H.POS and D.CNT inputs indicates to system controller 300 that magazine 50 is at Pos(1). This condition acts as a home-position signal. The remaining positions are detected by counting the D.CNT signal as magazine 50 moves in a given direction. Returning now to FIG. 10, system controller 300 applies a signal level to an ST.UP output and an ST.DWN output. The ST.UP and ST.DWN outputs are connected to a motor drive circuit 315. Motor drive circuit 315 controls a magazine motor 316, which rotates in a reverse direction in response to the output from motor drive circuit 315. The rotary outputs of magazine motor 316 transmits, via a selection mechanism 317, to either magazine vertical transport mechanism 318 or cam member drive mechanism 319. Selection mechanism 317 is controlled by tray/carriage transport mechanism 309 in response to the position of the selected carriage. When a selected carriage 51-57 is in the store position, magazine vertical transport mechanism 318 is selected. Magazine 50 moves upward when the ST.UP signal is "H" and moves downward when the ST.DOWN signal is "H". When both signals are "H," motor drive circuit 315 outputs short, applying a magnetic brake to magazine motor 316. When both signals are "L," motor drive circuit 315 outputs disconnect, releasing the magnetic braking action. Selection mechanism 317 transfers rotary input to cam member drive mechanism 319 when a selected carriage is in a position other than the store position (i.e., the playback or eject position). If the ST.UP signal is "H", cam 110 turns clockwise, moving optical mechanism 200 downward. If the ST.UP signal is "H," cam 110 turns counter-clockwise, moving optical mechanism 200 upward. System controller 300 also has a D.DET input to which signals are applied by a disc sensor 328 to register in memory the presence of a disc 1 in a selected carriages. Optical head 203 is movably connected to optical mechanism 200. Optical head 203 uses a laser to read recorded information from disc 1, generating a playback signal responsively to information recorded therein. The playback signal is applied to signal processor circuit 320 via a RF amplifier 322. Signal processor circuit 320 generates Lch and Rch audio data following EFM demodulation, de-interleaving and error correction to the raw signal. Audio data are sent to digital-to-analog converters 323 and 324, respectively, for digital-to-analog conversion. The analog output signals are applied to low pass filters 325 and 326, respectively. System controller 300 connects to a servo signal processor circuit 321, which controls a focus servo, a tracking servo and a feed servo on optical head 203. Servo signal processor circuit 321 also controls a CLV servo of a spindle motor 327. The operation of system controller 300 in conjunction with the remaining elements of the disc playback device are shown in the flowcharts of FIGS. 12-22, and the corresponding time charts shown in FIGS. 23-29. In the flowcharts, "n" refers to the selected disc number (carriage number) set responsive to a disc selection key, while "m" refers to the current position of magazine 50. Flag(m) indicates the presence of a disc on the m th storage position of magazine 50, where m is an index indicating the storage position number (e.g. Flag(3)=1 indicates that a disc is present in third carriage 53). Referring now to FIG. 12, system controller 300 follows the operation in the MAIN flowchart, in which system controller 300 awaits depression of a command key, or the completion of the playback mode for a disc. Each of the functions shown in FIG. 12 is referred to in the detailed flow descriptions of later figures. Thus, further description of FIG. 12 is unneccesary, and is omitted. Referring now to FIGS. 13-15, when an eject key is pressed while tray 20 is in the eject position, control by system controller 300 passes from step S1 of FIG. 12 to step S11 of FIG. 13. Step S10 is the first step in a JOB EJECT routine, shown in FIG. 11. Beginning with step S11, the JOB EJECT routine proceeds through operation TC2 of FIG. 23. Operation TC2 details how the device goes from the eject mode to the stop mode by returning the tray to the load position and the selected carriage to the store position. In step S11, system controller 300 applies the "H" level is to the REAR output to retract tray 20 toward its close position. Simultaneously, cam member 110 rotates toward the DOWN range shown in FIG. 9. Cam member 110 rotates counterclockwise responsive to a "H" level to the ST.DWN output. This also moves lower disc-lock shaft 251 downward from the lock position (indicated in FIG. 5). When lower disc-lock shaft 251 arrives at the unlock position and the POS 3 signal is set to "L" as a result of the rotation of cam 260, system controller 300 activates the electromagnetic brake for motor 316 by applying the "H" level to the ST.UP output to short motor drive circuit 315 for 50 msec. Following the first application of the brake, system controller 300 proceeds to step S12 unless cam member 110 over-rotates past the DOWN range. If cam member 110 over-rotates beyond the desired range, system controller 300 applies the "L" level to the ST.DWN output, driving cam member 110 clockwise. When the POS 2 signal changes to "H," system controller 300 sets the ST.DWN signal to "H", magnetically braking magazine motor 316 for 50 msec. At step S12, system controller 300 waits for the CENTER input signal to change to "L" in response to photo-interrupter 306. The CENTER input changes upon arrival of the selected carriage at the playback position. Once tray 20 is in the load position and the selected carriage disengages tray 20, the "L" level is applied to the CENTER output by switch 313. When the CENTER output signal changes to "L," control passes to step S13 where system controller 300 determines if a disc is present in the selected carriage. The presence (or lack thereof) of a disc in the selected carriage is indicated by the D.DET signal. If a disc is present, the D.DET signal is "L," and the corresponding FLAG(m) is set to "1" at step S15. A D.DET signal of "H" indicates the absence of a disc, and FLAG(m) is set to "0" at step S14. After setting FLAG(m), system controller 300 waits for the STORE signal to change to "L" at step S16, which indicates that the selected carriage has returned to magazine 50. On occasion, two discs may be placed accidentally into a tray 20 while in the eject position. If two discs 1 were set in selected first carriage 51, the top disc would hit a rim 21 of tray 20 when selected first carriage 51 moves from the playback position to the store position. Once selected carriage 51 withdraws to its store position, the top disc would fall into tray 20, jamming the device and damaging the disc when magazine 50 moves. In order to prevent such damage, the present invention checks to ensure that tray 20 is clear before moving magazine 50. Following a "L" STORE signal, system controller 300 again checks the D.DET signal at step S17. If the D.DET signal is "H" (no disc present in tray 20), control passes to step S18 (the last step of Operation TC2), where system controller 300 activates the electromagnetic brake for motor 316 by setting FRONT output signal to "H", shorting the input leads to magazine motor 316 for 50 msec. At step S150, each Flag(m) is checked to determine if any discs are stored in magazine 50. If a Flag is detected, then magazine 50 moves to POS(4) at a step 151, thereby securing any 8 cm disc in first carriage 51 such that it cannot slip into the larger 12 cm cavity. Finally, at step S19, a MODE variable is set to indicate a "STOP" mode and control returns to the MAIN routine of FIG. 10. If D.DET signal is "L" at step S17, indicating the presence of a disc, system controller 300 sets the REAR signal to "L" at step S20 and control passes to step S21 of FIG. 14. Beginning with step S21, the JOB EJECT routine proceeds through operation TC4 of FIG. 24. Operation TC4 details how the device secures the magazine prior to entering into the eject mode. Referring now also to FIG. 14, at step S21, system controller 300 sets the FRONT signal to "H", moving selected first carriage 51 toward the playback position. CENTER input signal changes to "L", indicating arrival of selected first carriage 51 at the playback position, at a step S22. Once CENTER input signal changes to "L", system controller 300 resets FLAG(m) to "0" at a step S23. At a step S24, system controller 300 moves cam member 110 to the LOCK range. ST.UP is set to "H," rotating cam member 110 clockwise to move lower disc-lock shaft 251 toward the lock position. Once lower disc-lock shaft 251 moves to the lock position and the POS 1 signal is "L", the ST.DWN output signal is set to "H" to brake magazine motor 316. In this state, the remaining discs in magazine 50 are secure, and will not shift due to shock or inclination of playback device 1000. Then, at step S25, system controller 300 waits for the EJECT signal to change to "L" when tray 20 is brought to the eject position. System controller 300 applies the "H" level to the REAR output and magnetically brakes tray motor 308 for 50 msec. At step S27, the MODE variable is set to indicate an "EJECT" mode and control is returned to the MAIN routine. Referring now to FIGS. 15 and 25, when the eject key is pressed during a "PLAYBACK" mode, system controller 300 proceeds from step S1 of FIG. 12 through step S10 of FIG. 13 to steps S28 and S29 of FIG. 15. At step S30, disc playback is halted and cam member 110 rotates to the LOCK range shown in FIG. 9. Beginning with step S30, The JOB EJECT routine proceeds through operation TC3 of FIG. 25. Operation TC3 details how the device secures the magazine prior to ejecting a disc from the playback position. System controller 300 applies an "H" level to the ST.UP output. System controller 300 then rotates cam member 110 clockwise to bring optical mechanism 200 into the lower position and lower-disc-lock shaft 251 to the lock position. Once lower disc-lock shaft 251 arrives at the lock position and the POS 1 signal becomes "L", motor 316 magnetically brakes for 50 msec by a "H" ST.DWN signal. Following braking, an "H" level signal is applied to the FRONT output at a step S31, moving tray 20 to the eject position. At step S32, FLAG(m) is reset to "0". After tray 20 arrives at the eject position, causing the EJECT input signal to change to "L", an "H" level at the REAR output magnetically brakes tray motor 308 for 50 msec. Finally, the MODE variable is set to indicate the "EJECT" mode and control returns to the MAIN routine of FIG. 10 in a step S35. When the eject key is pressed during the "STOP" mode (the mode when all carriages 51-57 are in the store position), system controller 300 proceeds from step S1, through steps S10, S28, S36 to step S37, at which the selected disc number "n" is compared with "m". If they are identical, control proceeds to the flowchart of FIG. 14, described as previously. If not, magazine 50 moves to Pos(n) prior to control proceeding to the flowchart of FIG. 14. Referring now to FIGS. 16 and 26, when a play key is pressed during the "EJECT" mode, system controller 300 proceeds from step S2 of FIG. 10 to steps S40 and S41 of FIG. 16. At step S41, an "H" level to the REAR output moves tray 20 toward its close position. At the same time, cam member 110 rotates counterclockwise to the DOWN range, moving lower disc-lock shaft 251 downward from the lock position (indicated in FIG. 5). When lower disc-lock shaft 251 arrives at the unlock position and the POS 3 signal is set to "L" as a result of the rotation of cam 260, system controller 300 activates the electromagnetic brake for motor 316 by applying the "H" level to the ST.UP output to short motor drive circuit 315 for 50 msec. Following the first application of the brake, system controller 300 proceeds to step S42 (unless cam member 110 over-rotates, thereby requiring restoration in the manner described previously). At step S42, system controller 300 waits for the CENTER input signal to change to "L," in response to photo-interrupter 306. When the CENTER output signal changes to "L," control passes to step S43 where system controller 300 determines if a disc is present in the selected carriage. If a disc is present, the D.DET signal is "L," and the corresponding FLAG(m) is set to "1" at step S15. Tray 20 moves to the playback position at step S45. When the CENTER input signal terminal state changes to "L," system controller 300 outputs an "H" signal level from the FRONT output braking tray motor 308 for 50 msec. After braking, if tray motor 308 rotated past the playback position, an "L" level is output from the REAR output, and the FRONT output is cycled between "H" and "L" with a 50% duty cycle and a cycle period of 10 msec. Selected first carriage 591 thus moves in the eject direction at a low speed. Once the CENTER input signal changes to "L," an "H" level is output from both the FRONT and the REAR output terminals braking tray motor 308 for 50 msec. At step S46, system controller 300 brings cam member 110 to the UP range, shown in FIG. 9. An "H" signal level is applied by the ST.DWN output, rotating cam member 110 counterclockwise. Optical mechanism 200 moves toward its upper position, whereupon the POS 1 signal changes to "L". Magnetic braking is activated by an "H" level signal is output from the ST.UP. After the braking, signal processor circuit 320 and servo signal processor 321 are controlled to begin the playback procedure at step S47. Once disc playback has begun, the MODE variable is set to indicate the "PLAY" mode and control returns to the MAIN routine at step S48. If no disc is present in the selected carriage (D.DET is "H"), control proceeds from step S43 to step S49. FLAG(m) is set to "0". At step S50, system controller 300 waits for the selected carriage to arrive at the store position and the STORE input signal changes to "L", at which time system controller 300 outputs an "H" level at the FRONT output at step S51 to brake tray motor 308. At step S152, each Flag(m) is checked to determine if any discs are stored in magazine 50. If a Flag is detected, then magazine 50 moves to POS(4) at a step 153, thereby securing any 8 cm disc is first carriage 51 such that it cannot slip into the larger 12 cm cavity. Finally, at step S52, a MODE variable is set to indicate a "STOP" mode and control returns to the MAIN routine of FIG. 12. Referring now to FIGS. 17, 27 and 28, if the play key is pressed during the "STOP" mode, system controller 300 proceeds to a JOB PLAY routine, through steps S40 and S53, to step S154 at which the selected disc number "n" is compared with "m". If they are identical, control proceeds to step S54 where FLAG(m) checked. If not, magazine 50 moves to POS(n) from which control proceeds with step S54. At step S54, control branches to step S55 if FLAG(m) is "1" or to step S62 if FLAG(m) is "0". As stated, when FLAG(m)="1", a disc 1 is present on the selected carriage. If FLAG(m) was "0" at step S62 system controller 300 searches all flags sequentially from FLAG(1) to FLAG(7). If a flag set to "1" is found, control proceeds to step S63, wherein magazine 50 moves to the position corresponding to the flag which was set to "1". Control then passes to step S55. If all of the flags are set to "0" in step S62, control immediately returns to the MAIN routine of FIG. 10. In the latter case the pressing of the play key is, in effect, ignored. At a step 55, operations TC6 and TC7 commence as shown in FIGS. 27 and 28 respectively. Operation TC6 involves transferring a disc from a selected carriage in magazine 50 to the playback position, from which playback commences. Operation TC7 is a branch of TC6, responsive to no disc being present in the playback position, for returning the selected carriage to magazine 50. System controller 300 outputs an "H" level signal at the FRONT output at step S55. The selected carriage moves out of magazine 50 toward the playback position until the CENTER input signal changes to "L" in step S56. Once the selected carriage arrives at the playback position, system controller 300 checks the D.DET input at step 57 to check if a disc 1 is present in the selected carriage. Step S57 thereby corrects data errors in FLAG(m) (possibly due to a power loss) to prevent unnecessary operations of the device. If D.DET is "H", system controller 300 sets FLAG(m) to "0" at step S64. At step S65, an "L" signal level is applied to the FRONT output and an "H" signal level is applied to the REAR output, moving the selected carriage back to its store position. At step S67, once selected first carriage 51 arrives at the store position as indicated by the STORE input signal changes to "L", system controller 300 applies an "H" level to the FRONT output terminal and brakes tray motor 308 for 50 msec. This step completes operation TC7, after which control returns to step S62. If at step S57, the D.DET input signal is "L," control proceeds to step S58, where system controller 300 moves tray 20 to the playback position. At step S59 cam member 110 rotates until it is in the UP range. After the CENTER input signal changes to "L," system controller 300 outputs an "H" level at the REAR signal terminal, braking tray motor 308. If, the carriage overshoots the playback position, an "L" signal level is output from the FRONT output terminal and the REAR output is cycled, at a 50% duty cycle with a 10 msec cycle period, slowly bringing the selected carriage to the playback position. Once the CENTER input signal changes to "L," "H" levels are output at both the FRONT signal terminal and the REAR signal terminal for 50 msec. to magnetically brake tray motor 308. Next, system controller 300 outputs an "H" signal level at the ST.DWN output terminal. Cam member 110 rotates counterclockwise, moving optical mechanism 200 toward its upper position. When optical mechanism 200 arrives at the up position and the POS 1 signal changes to "L," braking is induced by an "H" level ST.UP. This step completes operation TC6, after which control proceeds to step S60, where disc playback is initiated. At step S61, the MODE variable is set to indicate the "PLAY" mode. Control then returns to the MAIN routine. Referring now also to FIGS. 18 and 29, when the STOP key is pressed during the "PLAY" mode, system controller 300 proceeds from step S3 of FIG. 12 through steps S70 and S71 of FIG. 18. Disc playback halts at step S71. At a step S72, operation TC8 begins, in which the selected carriage returns to the store position from the playback position. At step S72, cam member 110 rotates toward the DOWN range. System controller 300 sets the ST.UP signal to "H". Cam member 110 rotates clockwise to move to move optical head 203 and lower disc-lock shaft 251 downward. System controller 300 compensates for any overshoot as described previously. When optical head 203 reaches the down position and the POS 2 signal changes to "H," system controller activates the brake. Then, at step S73, system controller 300 outputs an "H" signal level from the REAR output the selected carriage to return the store position. Control passes to step S75 when the selected carriage arrives at the store position and the STORE input signal changes to "L". System controller 300 determines if a disc is present by the D.DET input signal. If no disc is present (D.DET signals is "L") at step S78, system controller 300 sets the REAR output signal to "L", whereby control proceeds to the flowchart of FIG. 14 as above. IF a disc is present (D.DET is "H") control proceeds to step S76, where tray motor 308 magnetically brakes as described previously. This concludes operation TC8, and control proceeds to step S156. At step S156, each Flag(m) is checked to determine if any discs are in magazine 50. If a Flag is detected, then magazine 50 moves to POS(4) at a step 157, thereby securing any 8 cm disc is first carriage 51 such that it cannot slip into the larger 12 cm cavity. At step S77 the MODE variable is set to indicate the "STOP" mode and control returns to the MAIN routine. Mode control panel 301 includes a plurality of DISC selection keys (not shown), one for each of the seven carriages 51-57 in magazine 50. Referring now also to FIGS. 19, when one of the DISC selection keys is pressed, system controller 300 branches from a corresponding one of steps S4 through S7 of FIG. 12 to a corresponding JOB DISC-N routine (steps S80-S83) shown in FIG. 19, where N is the number of the DISC selection key that is pressed. A constant n is set to "1", "2", . . . "7" according to the DISC selection key pressed. If the disc selection key is depressed while the device is in the "EJECT" mode, control proceeds to operation TC2 (movement from the eject position to the store position) through a series of steps S85-S92 and S94. These steps are identical to steps S11-S18 and S20, respectively, and need not be repeated here. After step S92 in which the tray motor 308 stops, magazine 50 moves to POS(n). Control then proceeds to step S21 in FIG. 14, discussed above. Referring now to FIGS. 20 and 29, when a DISC key is pressed during "PLAY" mode, system controller 300 proceeds from the corresponding JOB DISC routine (the one of S81-S83 corresponding to the key pressed) to steps S84, S95 and S96, wherein FLAG(m) is checked for the presence of a disc, where m is the DISC key number that was pressed. If no disc is present (FLAG(m) is "0") control immediately returns to the MAIN routine and the pressing of a DISC key is, in effect, ignored. If a disc is present (FLAG(m) is "1"), control proceeds to step S97 where system controller 300 halts disc playback. Beginning with step S98, the routine proceeds through operation TC8 (movement from the playback position to the store position) through a series of steps S98-S102. These steps are identical to steps S72-S76 and S78, and need not be repeated here. After step S103 in which the tray motor 308 stops, magazine 50 moves to POS(n). Control then proceeds to step S105 in FIG. 21. Referring now also to FIG. 21, both operations TC6 and TC7 commence at step 105 through S115, which are identical to steps S55-S61 and S64-S67 of FIG. 17 (store position to playback position; if a disc is not in the selected carriage, return to store position), described above. Following a step 115 in which motor 308 is braked, each Flag(m) is checked to determine if any discs are stored in magazine 50. If a Flag is detected, then magazine 50 moves to POS(4) at a step 159, thereby securing any 8 cm disc is first carriage 51 such that it cannot slip into the larger 12 cm cavity. At step S116 the MODE variable is set to indicate the "STOP" mode and control returns to the MAIN routine. When a DISC key is pressed during the "STOP" mode, system controller 300 proceeds to the appropriate JOB DISC procedure as described above. After setting variable n to a value corresponding to the DISC key pressed, control passes through steps S84, S95 and S117 to step S118. At step S118 magazine 50 moves to position Pos(n), the position corresponding to the key pressed, and control returns to the MAIN routine. Referring now to FIG. 22, the operation of continuous playback in play mode is described. System controller 300 detects when playback of a disc is completed from signal processor circuit 320. Control proceeds from step S8 of FIG. 12 to step S120 in FIG. 22, where the disc is halted. Commencing with step S121, the routine proceeds through operation TC8 (movement from the playback position to the store position) through a series of steps S121-S126. These steps are identical to steps S72-S76 and S78 of FIG. 18, discussed above. At a step S127, the flags are checked sequentially beginning with FLAG(m+1) through Flag(7) to located the next disc in magazine 50. If no disc is present, then all flags are searched. If a disc is detected, magazine 50 moves to POS(4) to secure first carriage 51, as previously described. Following magazine movement, or in the event that no disc is in magazine 50, the MODE variable is set to indicate the "STOP" mode and control returns to the MAIN routine. If a Flag is detected in Flag(m+1) through Flag(7), then magazine 50 moves to POS(n) at step S129, where n is the first sequential carriage in which the flag was detected. Step 130 commences both operations TC6 and TC7. Steps S130-140 are identical to steps S55-S61 and S64-S67 of FIG. 17 (store position to playback position; if a disc is not in the selected carriage, return to store position), described above. If no disc is present, control proceeds from S140 to S127. If a disc is present, disc playback resumes, MODE is set to play, and control returns to the main routine. Referring now to FIGS. 30-32, a display 329 indicates various modes of operation and the presence of discs as the foregoing operations occur. Various alterations of the embodiment described above may be effected by those of ordinary skill in the art, having the benefit of this description, without departing from the scope and spirit of the present invention. For example, while the embodiment described uses carriages to transport discs, it is possible to eliminate the use of carriages in the practice of the present invention. It is also possible to transport a selected disc by rollers engaging either surfaces or edges of the selected disc. Alternatively, a belt may be substituted for the rollers. Another possible alteration is the use of an independent drive source for raising and lowering lower disc lock shaft 251 rather than employing cam member 100 which is also used to raise and lower the optical mechanism 200. Alternate methods can also be used to secure 8 cm discs. In the stop mode, an empty carriage could be moved to the store position, thereby securing the remaining occupied carriages. If additional carriages had 8 cm capacity, a different rest position (other than Pos(4)) could be used. Thus, the present invention provides a mechanism to ensure secure storage of discs in magazine 50 regardless of mechanical shocks or a physical orientation of disc player 1000. This allows disc player 1000 to be used in environments outside of the stable confines of a dwelling, regardless of whether 12 cm discs or 8 cm discs are used. For instance, disc player 1000 is useful in applications requiring portable hand held operation or vehicle mounted operation. Having described preferred embodiments of the invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention as defined in the appended claims.

A disc player has a magazine for storing discs and a disc transport mechanism transporting a selected disc between a playback position outside the magazine and a store position located within the magazine. The carriages are stacked upon each other and pivotally supported within the magazine. The carriages are extracted from the stack by lifting a front end of a carriage above a selected carriage. Subsequent to the lifting of the carriage, the selected carriage is withdrawn from the magazine to the playback position. When a selected carriage is moved to the playback position, the discs on carriages above and below the selected carriage are prevented from shifting with the removal of the selected carriage by coaxial opposing shafts which extend through spindle holes in the discs on the carriages above and below the selected disc. A closeable gap between the two shafts permits the selected disc to be shifted. The gap is closed, except when a carriage is being shifted into or out of the magazine, thereby preventing discs and their carriages from shifting due to vibration or tilting of the cabinet. When the device is in a stop mode, the magazine shifts to pierce any carriages capable of holding discs of different sizes, thereby preventing smaller disc from moving into recesses for larger discs.

This application is based on and claims priority from provisional patent application, Ser. No. 60/272,199, filed Feb. 28, 2001. BACKGROUND OF THE INVENTION Pedestrians and slow-moving vehicles such as bicycles, must often share roads and highways with many types of fast-moving vehicles. In many cases, the pedestrian or slow-moving vehicle may not be visible to oncoming traffic. The pedestrian or slow moving vehicle, may not be aware of the approaching high speed traffic. This is a situation that can easily result in a serious accident. Bicycles are typical of slow-moving vehicles with high potential for being victims of accidents with faster vehicles. Bicyclists rarely move as fast as normal highway traffic. They often are not completely aware of their surroundings due to poor visibility, helmets, wind noise, varying terrain, and other environmental factors. Most cycling traffic accidents occur either because the cyclist did not anticipate the approaching vehicle (often from the rear) or the driver of the vehicle did not see the cyclist in time to take evasive action. In addition to cyclists, there are many other potential victims of fast-moving vehicles both on and off the road. These include pedestrians, skiers, highway workers, roller-bladders, skaters, and other personnel that must use highways, roads, or trails where visibility may be limited. Larger vehicles with limited visibility, including motorcycles, horse-drawn vehicles, and farm vehicles, may also be involved in accidents with rapidly approaching vehicles. To reduce the possibility of accidents, slow moving, limited-visibility vehicles, and pedestrians would be aided by a proximity detector that would warn them of oncoming traffic and make the oncoming traffic aware of their presence. A vehicle proximity-alerting device could help avoid many of these potential accidents and possibly decrease the morbidity and mortality of cyclists, pedestrians, and others. There are a large number of possible applications for a proximity detector that would warn users of oncoming traffic and make the oncoming traffic aware of their presence. The following are some examples of slow-moving and/or low-visibility road users in need of a vehicle proximity-alerting device: motorized: motorcycles, farm vehicles, construction vehicles, mail delivery vans, buses; non-motorized: bicycles, skateboards, roller blades, scooters, skates, small battery-powered cars, infant strollers, horses, horse-drawn vehicles; and pedestrian: children, walkers/joggers/runners, and highway workers. The following are some examples of slow-moving and/or low-visibility off-road users of a vehicle proximity-alerting device: motorized: airport equipment (baggage cars, tow truck, etc.), amusement park trams, motor boats; non-motorized: off-road bicycles, row boats, sailboats; and pedestrian: skiers, and construction workers. One example of a practical application is be a vehicle proximity-alerting device for motorcycles. Motorcycle accidents involving other vehicles are often fatal to the motorcycle rider. Although a motorcyclist is usually alert to the presence of other vehicles, it is not always the case. Also, motorcycles are often not perceived by motorists. The “Motorcycle Accident Cause Factors and Identification of Countermeasures,” was a study conducted by the University of Southern California (USC). With funds from the National Highway Traffic Safety Administration, researcher Harry Hurt investigated almost every aspect of 900 motorcycle accidents in the Los Angeles area. Additionally, Hurt and his staff analyzed 3,600 motorcycle traffic accident reports in the same geographic area. Some of the findings relevant to vehicle/motorcycle accidents from the report are summarized as follows: 1. Approximately three-fourths of these motorcycle accidents involved collision with another vehicle, which was most usually a passenger automobile. 2. In the multiple-vehicle accidents, the driver of the other vehicle violated the motorcycle right-of-way and caused the accident in two-thirds of those accidents. 3. The failure of motorists to detect and recognize motorcycles in traffic is the predominating cause of motorcycle accidents. The driver of the other vehicle involved in collision with the motorcycle did not see the motorcycle before the collision, or did not see the motorcycle until too late to avoid the collision. 4. Conspicuity of the motorcycle is a critical factor in the multiple vehicle accidents, and accident involvement is significantly reduced by the use of motorcycle headlamps (on in daylight) and the wearing of high visibility yellow, orange, or bright red jackets. 5. The view of the motorcycle or the other vehicle involved in the accident is limited by glare or obstructed by other vehicles in almost half of the multiple-vehicle accidents. SUMMARY OF THE INVENTION Applicants proximity-alerting device is designed to accommodate a wide range of applications. For some applications, the proximity-alerting device is designed for a specific application. For example, at night a pedestrian or road worker may not require as bright a warning light as a daytime user. For this application, it is be feasible to use flashed LEDs, thereby reducing power and weight so that the detector could conveniently be worn on a person's back. Applicant provides approaching-vehicle proximity-alerting device designed to alert both the oncoming vehicle driver and the user of the device. Such a device includes several components. A low-power radar or another appropriate detector determines vehicle proximity (by velocity and/or distance). A flashing light is produced by the device to alert the driver of the oncoming vehicle by stimulating his visual perception. Depending on the user application (pedestrian, bicyclist, etc.), the device includes an audible, tactile and/or visual signal emitter at the same time that the driver of the oncoming vehicle is alerted by the flashing light. The vehicle-detection, visual-alert, and audible-alert circuits control and timing circuits initiate the alert upon correct detection of a vehicle. The alert device may be incorporated into other equipment such as, music earphones, heart rate monitors, and ear protection devices. Power for all circuits is supplied by internal batteries or supplied by an external power source in some applications. The detection circuits typically consist of a simple low-power continuous wave Doppler radar. Currently, a complete RF Doppler radar module based on GUNN diode technology can be purchased commercially for approximately $75 (MA/COM Model MA87728-MO1). A similar module has a planar array and printed circuit board The detector and additional electronics, including control circuits and output circuits (audible and visual), are typically provided as a single printed circuit board. For some applications, the device power requirements reduce the duty cycle of one or more circuits. As an example, the duty cycle of a GUNN diode radar may readily be reduced by a factor of ten. The radar may operate for ten milliseconds and be in an off state for ninety milliseconds. During the ninety milliseconds off state, an oncoming vehicle traveling at one hundred miles per hour would close by only thirteen feet. For the GUNN module previously described, the normal detection range would be on the order of about two hundred feet. Reducing the duty cycle by a factor often would reduce the range less than 7%. Similar duty cycle reduction on the other circuits may also be appropriate for some applications. Infrared radar is provided as an alternate detector, especially for night use. Infrared radars typically use solid-state infrared laser diodes and are known as LADARs. They generally use a semiconductor diode to generate laser light. Most vehicle traffic LADARS emit laser light at around 904 nm wavelength. Other wavelengths are possible; for example, aluminum gallium arsenide (AlGaAs) diodes emit light at a wavelength of 850 nm. Gallium arsenide (GaAs), classified as an injection laser, emits light between 880 nm to 900 nm. Other wavelengths are possible using other materials or alloys. The Federal Communications Commission (FCC) regulates radiated emissions from high-speed circuits such as the processing circuits inside a LADAR, but not infrared and light frequencies. The Federal Drug Administration (FDA) Center for Devices and Radiological Health (CDRH) regulates laser products sold in the United States. Traffic LADARs are Class 1 devices (by American National Standards Institute definition) and considered eye-safe based on current medical knowledge. New ultra-wideband radar technology based on very narrow pulses has the potential for providing both range and speed information using very low power. Although not commercially available at this time, there is potential for use of ultra-wideband radar as the vehicle detector for a proximity-alerting device. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a housing containing some of the circuits and elements of the present invention as well as some of the circuits and elements of the present invention that are external to the housing, and block diagram FIG. 2 illustrates an external, isometric view of the housing invention illustrating some of the components thereof. FIG. 2A is a perspective view of external controls and indicator of the present invention suitable for mounting at a position or location removed from the housing. FIG. 3 is a side elevational view of Applicant's present invention as mounted to a bicycle. FIG. 3A illustrates components of Applicant's present invention as mounted to the handle bar of a bicycle. FIG. 4 is an overhead view of Applicant's present invention as mounted to a bicycle in an operating situation. FIG. 5 is an overhead view of Applicant's present invention mounted to a motorcycle in an operating situation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A block diagram of a vehicle proximity-alerting device 10 is shown in FIG. 1 . The oncoming vehicles are detected by radar or other form of vehicle proximity detector circuit 12 that gives an indication of the approaching vehicle velocity and/or range information. Doppler or ultra wideband (narrow pulse) radar circuits incorporated into the detector circuit 12 provide the detector function, although other detectors such as laser detection and ranging (LADAR) circuits may also be suitable. An appropriate transmitting and receiving antenna 12 A is included as part of the detector circuit 12 . The control and timing circuit 18 (implemented, for example, by a conventional microprocessor or microcontroller) interprets the signals received from the detector circuit 12 . When the range and/or velocity of the oncoming vehicle is interpreted by detector control and timing circuit 18 as meeting the requirements preselected (distance and/or speed) for an alert, the control and timing circuit 18 then activates both the rider alarm circuit 14 and the vehicle alert circuit 16 . When the vehicle is no longer present, the rider alaim circuit 14 and vehicle alert circuit 16 terminate their alerts. These circuits may provide secondary functions (including a theft alarm beacon). As part of the control and timing circuit 18 and mounted within housing 22 there may optionally be manually activated control switches including those with the following functions: on-off switch 18 B; self-test mechanism 18 C; battery status check indicator 18 E; and headphone connection 18 G. (See FIG. 2 ). Once initiated by the control and timing circuit 18 , the vehicle alert circuit 16 will supply power to an xenon strobe, light emitting diode (LED), or other bright light or visual output means 16 A at a pulse rate that would be best perceived by an oncoming vehicle. The pulse rate would typically be approximately 3 to 5 pulses per second to distinguish it from other vehicle light pulsing modes. When the detection circuit 12 and control and timing circuit 18 indicates that a vehicle is no longer present, the vehicle alert circuit 16 ceases to supply power to the flashing light source(s) or other visual output 16 A. Changes in light conditions (day to night, etc.) may require the addition of a intensity control circuit for the circuit output that would change intensity of the flasher output in response to an ambient light sensor 16 B. Once initiated by the control and timing circuits 18 , the rider alarm circuit 14 supplies an appropriate tone, beep, etc., to an alarm output device 14 A (for example, a loud speaker, piezoelectric transducer or buzzer) at a volume or level that would be best perceived by the rider. When the detection circuit 12 and timing circuit 18 indicates that a vehicle is no longer present (within the pre-selected detection range), the rider alarm circuit 14 ceases to supply a signal to the alarm output device(s) 14 A. In addition to user volume-level control 18 I (limited to some minimal value), an automatic level control 18 K may be necessary for applications where ambient noise levels vary. A suitable ambient noise level signal to (e.g. in 18 A) provides yautomatic level control 18 K which can be implemented by the aforementioned microprocessor or microcontroller). The power source 20 supplies the electrical power required by all active circuits within the device 10 . Depending on the user application, power is to be supplied by either rechargeable or primary batteries. In some applications, external power source 28 , such as a vehicle's electrical system, is supplied directly to the active circuits while simultaneously charging backup batteries. The need for external controls and indicators 18 A (meaning not withing housing 22 ) is application dependent. In some cases, external controls and indicators 18 A consist of only a remote on/off switch 18 B′ and/or a switch for testing the operation of the device 18 C′ (self-test). In other applications, they include an on/off switch 18 B′, visual alert 18 D′, battery status indicator 18 E′, vehicle velocity indicator 18 F′, and headphone connection 18 G′, etc. (See FIGS. 2 A and 3 A). If a vehicle velocity indicator 18 F′ is included, it may be a bar graph. The output alarm device may include blinking light 18 F,″ which may increase in speed as the distance between the car and device user narrows (See FIGS. 2 A and 3 A). The blinking light may be used with or in place of a loud speaker. The external controls and indicators 18 A may be included or be made part of a separate speedometer or a heart rate monitor. Housing 22 and control and timing circuit 18 may contain a port 18 H (or several) to connect the external controls and indicators 18 A to the control and timing circuit 18 by way of an external control connector 26 . (See FIGS. 2, 2 A and 3 A). External controls and indicators 18 A may be mounted in front of the bicycle, specifically the handlebars, by way of a mounting bracket 28 . (See FIG. 3 A). A vehicle proximity-alerting device 10 is intended to alert both the user of the device 10 and the driver of the oncoming vehicle. But, in some instances, alerting the driver of the oncoming vehicle may be of greater value. In accidents between oncoming motor vehicles and pedestrians or slower vehicles, the vehicle driver involved in the collision often does not see the pedestrian/slower vehicle before the collision, or with enough time to avoid the collision Slow vehicles and even pedestrians often use lights to alert other vehicles to their presence, but the lights are not always effective because they are not perceived. On the other hand, it has been shown that a distinct change in the light from a scene is easily perceived. Therefore, the alerting effectiveness of a flashing light is compounded if the flashing is initiated while the motorist is proximally located within sight of the system. Also, not having the light flash constantly saves power (important for battery life) and would be less distracting to other observers. Of course, even if the oncoming vehicle did not see the flashing light, the device user would benefit from an audio or visual alert that a potentially threatening vehicle was approaching. Turning now to FIGS. 3, 4 , and 5 , the Applicant's vehicle proximity-alerting device 10 is exemplified by the bicycle application (FIGS. 3 and 4 ). The housing of the vehicle proximity-alerting device 10 would be mounted on a bicycle Bi, typically at seat post Sp and aimed (at least the antenna) to the rear of the bicycle (See FIG. 3 ). The visual output 16 A, such as a strobe light, would flash an intense light toward the vehicle Mv when the vehicle reached a preset distance Mdd (typically about 200 ′) from the bicycle informing the vehicle Mv driver of the bicycle. The motorist should quickly notice the initiation of a flashing light due to its high visibility. The alerted motorist could then maneuver to provide sufficient clearance while passing the cyclist. Simutaneously, a rider alarm output device 14 A, such as a loud speaker or in a preferred embodiment, a handlebar mounted light output 18 F″ or speaker will alert the rider (See FIGS. 2 and 3 A). The cyclist would then move closer to the side of the road, avoid turning into the vehicle, and become more alert at a time when vigilance is very crucial. The proximity-alerting device 10 is designed to accommodate various vehicle speeds and set distance combinations. For example, a bicyclist may not be concerned with vehicles approaching from the rear at closing speeds less than twenty miles per hour (see FIG. 4 ). At this closing speed, the vehicle should be able to maneuver to avoid the bicycle. By use of ranging information provided from the detector 12 , the distance to an oncoming vehicle can be made a factor in determining when to initiate the alert. The alert can be initiated when an oncoming vehicle is traveling at sixty miles per hour relative speed two hundred feet from a bicycle or at thirty miles per hour relative speed when one hundred feet from the bicycle. This would give about the same amount of warning time to respond to either vehicle. These alert parameters may be altered to provide optimal conditions in different applications, i.e. pedestrian, skier or motorcycle rider. Further, the device may be used to detect the presence of a vehicle at a preset distance, regardless of the vehicles closing speed. Product practicality for a given application often hinges on cost. Applicant provides a cost-effective detector including, low-cost packaging. For most applications, packaging as a single unit with housing 22 is provided. For example, a single bicycle seat post-mounted radar module may detect vehicles, fire a strobe, and sound an audible alarm to alert the cyclist. Two units (a control unit on the handlebars and radar on the rear) may be provided but will typically require additional packaging, including wire interconnections. An example of a two unit application includes a construction vehicle (Payloader, crane, etc.), where a dash-mounted visual alert would probably be of value to the user. Although primarily intended for use where the device user is not aware of oncoming vehicles, applicant includes embodiments where the timeliness of the alert would be of value even though the user is aware. One such application includes use on a motorcycle facing oncoming traffic. This situation has a high accident potential when an oncoming vehicle approaching a motorcycle from the front turns across the path of the motorcycle (see FIG. 5 ). If the closing speed is high, the motorcyclist may not have sufficient time to react. As alluded to in the Hurt report, vehicles not yielding the right of way cause many often serious or fatal motorcycle accidents. Thus, in FIG. 5, applicant provides forward-oriented proximity-alerting device 10 facing the oncoming traffic to “flash” an alert to the oncoming vehicle if the closing speed is too high for a motorcyclist to react. For traffic closing at less than that speed, the proximity-alerting device 10 may be adjusted so as not to flash an alert. Any orientation of the oncoming vehicle to the proximity detector may be of value if the threatened vehicle cannot react to the oncoming vehicle in time. In this situation, a forward-mounted vehicle proximity-alerting device is provided to flash a visual alert to an oncoming vehicle when the combined closing speed between the motorcycle and vehicle leaves minimal time for either vehicle to react. To minimize alert flashes to other oncoming traffic, the control and timing circuits 18 are designed to flash only when it determines (by distance and velocity measurement) that both the closing speed leaves minimal time for either vehicle to react and the oncoming vehicle is decelerating (preparing to turn). In this situation, an audible or a visual alert to the motorcyclist may be omitted (the motorcyclist is facing the vehicle), but should be included in the design to inform the motorcyclist that a vehicle alert has been flashed. Some applications of a vehicle proximity-alerting device 10 may also benefit from secondary capabilities of Applicant's device. For example, the motorcycle vehicle proximity-alerting device optionally includes a motion sensor in the control and timing circuit 18 that would detect motion of the motorcycle when no motion is expected (that is, for example, the motorcycle engine is not running). This motion information is used to sound the visual and audio alarms of possible theft or vandalism. If the motorcycle is stolen, the control and timing circuits 18 are optionally designed to initiate a silent beacon (no visual or audio alarms). The beacon would use the vehicle proximity-alerting device radar as a radio frequency transmitting beacon that may tracked by a remote receiver (not shown) for recovery of the motorcycle. These optional functions may also be useful for other high-value platforms such as farm and construction equipment. Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limited sense. Various modifications of the disclosed embodiments, as well as alternative embodiments of the inventions will become apparent to persons skilled in the art upon the reference to the description of the invention. It is, therefore, contemplated that the appended claims will cover such modifications that fall which the scope of the invention.

A cycle-mounted vehicle proximity warning device warns a cyclist that a vehicle is approaching the cycle from the rear. A like device, worn by a pedestrian, warns the pedestrian of approaching vehicles. The warning device includes a vehicle detector circuit and an antenna that transmits and receives. The vehicle detector circuit detects a vehicle as it approaches the cycle or pedestrian and emits a detection signal. An alarm circuit responds to the detection signal and communicates an audible, visual, or tactile warning to the cyclist or pedestrian. The vehicle proximity warning device also includes a vehicle alert circuit that can activate a bright flashing light aimed at the approaching vehicle for the purpose of alerting its driver of the cyclist or pedestrian proximity.

FIELD OF THE INVENTION The present invention pertains to systems and methods for equalizing an input signal to an optical vestigial sideband (VSB) filter. In particular, the present invention pertains to signal transmission systems wherein digitally modulated signals are to be filtered as optical signals by an optical VSB filter and then transmitted over an optical fiber. The present invention pertains particularly, but not exclusively, to systems and methods that incorporate a tapped delay equalizer which equalizes a digitally modulated input signal for transmission over an optical fiber, wherein tap weights for the tapped delay equalizer are derived from the output signal at the downstream end of the fiber optic. BACKGROUND OF THE INVENTION When an optical signal is modulated for transmission through an optical fiber on a carrier frequency f c (f c =C/λ where C is a constant and λ is the optical wavelength), the modulated information signal will have two symmetric sidebands that are centered on the carrier frequency. In order to reduce fading due to fiber dispersion, and to conserve bandwidth in the transmission of such a signal, the optimal solution is to filter out one of the sidebands, either above or below f c . For various technical reasons, however, simultaneous preservation of one complete sideband and a complete removal of the other sideband is impossible. Nevertheless, although one of the sidebands may be partially suppressed, the complete preservation of the other sideband for transmission is highly desirable. A partial solution for the difficulty mentioned above, is the use of a vestigial sideband (VSB) filter. As is well known in the pertinent art, a VSB filter is a band pass filter that effectively preserves one sideband while partially suppressing the other sideband. Just how much of the unwanted sideband can be actually suppressed, however, is a design consideration. As noted above, it is virtually impossible to suppress 100% of the unwanted sideband. The portion of the sideband which cannot be suppressed is then referred to as the vestigial sideband (VSB). During a signal transmission it will happen that the VSB, which is transmitted with the unsuppressed sideband, will introduce impairments (distortions) into the transmitted signal. For signal integrity, these impairments need to be avoided, or at least minimized. For example, it is known that telecommunication signals can be adversely affected by group delays (i.e. time delays of amplitude envelopes), and phase delays (i.e. time delays of signal phase). Both of these types of delays result from interferences caused by the VSB. Also, and perhaps of greater concern, are Inter Symbol Interferences (ISI) that are introduced by the VSB during the demodulation of digital signals from an analog carrier signal. In any event, an optical information signal which is transmitted over an optical fiber will be somehow corrupted. The primary object of VSB control is obviously to minimize impairments (distortions) in the received signal, while also preserving the integrity of the transmitted information signal as much as possible. With this objective in mind, closed loop feedback control technology has provided interesting possibilities. In the context of signal telecommunications, an overview of closed loop control for a desired system output requires comparing the actual output of a system with the actual system input. In the case of a telecommunications system which seeks to preserve signal integrity, the desired system output will be the same as the system input (i.e. a signal transmission that results in a non-corrupted signal). When they are not the same, the signal has been corrupted during transmission. In this later case, a comparison of the actual output with the actual system input will generate an error signal. In a communications system, where it is known that the transmitted signal will be corrupted, the object is then to minimize the error signal. In essence, the question is what feedback will most effectively minimize the error signal. An example of employing closed loop technology to control signal transmission using a VSB filter is provided by U.S. Pub. No. 2003/0058509 (hereinafter referred to as “Webb”). As disclosed in Webb, the control loop is used to adjust the wavelength of a laser that is providing the carrier frequency. Alternatively, Webb discloses the use of a wavelength control block to control the filter edge of the VSB filter. Unlike the disclosure of Webb, the present invention incorporates a tapped delay equalizer in the feedback loop which is established to reshape the input signal for the purpose of improving a VSB filter. In light of the above, it is an object of the present invention to provide a system and method for equalizing a digitally modulated signal, for input as an optical signal to an optical VSB filter, for transmission of the optical signal over an optical fiber. Another object of the present invention is to provide a device which employs a tapped delay equalizer to equalize a digitally modulated signal for subsequent conversion and filtering as an optical signal by a VSB filter for transmission over an optical fiber. Still another object of the present invention is to provide a system for using a tapped delay equalizer, in combination with a VSB filter, to transmit optical signals over an optical fiber which is easy to manufacture, is simple to use and which is comparatively cost effective. SUMMARY OF THE INVENTION In accordance with the present invention, a system is provided for transmitting a digital information signal, as an optical information signal, over an optical fiber. After transmission over the optical fiber, the optical information signal is converted back into a digital information signal for further transmission. An important aspect of the present invention is the incorporation of a vestigial sideband (VSB) optical filter into the system which has been equalized to improve the VSB filter. For the present invention, this improvement is further improved by equalizing the digital information signal that is provided as the input to the system. For the present invention, the additional improvement afforded by equalization is provided by a tapped delay equalizer. In particular, this equalization compensates for signal impairments introduced by the VSB filter. As envisioned for the present invention, the digital information signal can be a non-return to zero (NRZ) digital signal, a return to zero (RZ) digital signal, a quadrature amplitude modulation (QAM) signal, a duo-binary signal or any other suitable signal known in the pertinent art. Importantly, whatever digital information signal is used as the input signal, it will be characterized by a symbol rate, R s , and a time duration, T, for each symbol, with R s =1/T. Structurally, the system includes a transmitter which receives a digital information signal as an electrical input, and it outputs an optical information signal for transmission over an optical fiber. To perform this function, the transmitter includes a driver chip, an electrical to optical (E/O) converter and an optical VSB filter, such as an optical thin film filter. In this combination, the driver chip is provided for conditioning the electrical signal upstream of the E/O converter. To do this, the driver chip includes a tapped delay equalizer, an amplifier with gain and bias control, and a control circuitry for operating the driver chip. As indicated above, taps of the tapped delay equalizer are adjustable to alter the shape of the electrical signal (i.e. the digital information signal) that is input at the E/O converter. In detail, the tapped delay equalizer which is positioned on the driver chip to receive the digital information signal as an input will have an n-number of taps. For the present invention, a time delay, d t , between adjacent taps can be engineered as desired for the particular driver chip. Accordingly, the chip needs to be configured with d t <T. Moreover, although d t may be the same between all adjacent taps (i.e. d t−1 =d t =d t+1 ), depending on the needs of the particular system, this may not necessarily be so (i.e. d t−1 ≠d t and/or d t ≠d t+1 ). Further, using the n-number of taps, the adjustable equalizer will include an N-number of taps per symbol in the information signal. In general, the tapped delay equalizer is established with n-greater than N, and N greater than one (n>N>1). In this arrangement each tap is weighted, at least in part, based on the operational parameters of the VSB filter. As is well known by the skilled artisan, these operational parameters typically include a phase position of the VSB filter relative to the information signal, selectively measured amplitudes from the optical information signal, and group delays encountered between tap samples of the information signal. Operationally, the tapped delay equalizer is employed to reshape the input digital information signal, to thereby compensate for impairments which are introduced into the optical information signal by the optical VSB filter. It is noteworthy that this signal reshaping can also account for variations in signal quality due to the length of the optical fiber. Further, in some implementations of the present invention, signal quality downstream of the optical fiber can be measured and the resulting data included for adjustments of the tapped delay equalizer. On the driver chip, the amplifier with gain and bias control is connected to receive the shaped signal from the tapped delay equalizer. With this connection, the amplifier provides gain for the shaped signal, and it includes a biasing element to bias the shaped signal. The result here is an electrical digital information output signal from the driver chip which has a proper operating point. Control circuitry, in addition to the tapped delay equalizer and the amplifier, is also provided on the driver chip. As indicated above, with the connection between the amplifier and the control circuitry, a suitable gain and a bias for the amplifier can be established. On the other hand, the connection between the control circuitry and the tapped delay equalizer allows the tap weights for individual taps of the tapped delay equalizer to be adjusted. The collective result of these corrective actions is a digital information signal that is ready for conversion to an optical information signal. As indicated above, measurements of signal quality downstream of the optical fiber are to be used to adjust the equalizer. To do this, an analyzer is included in the system. Specifically, the analyzer is connected between the output of an optical to electrical (O/E) device at the downstream end of the fiber optic, and the driver/equalizer at the upstream end of the fiber optic. With this connection, the analyzer can be used to determine a transmission quality parameter such as a bit error rate (BER), along with other signal impairments mentioned above that have been introduced by the VSB optical filter and the optical fiber. In more detail, the analyzer is connected between the O/E device and the tapped delay equalizer of the driver/equalizer to analyze samples of the digital information signal that is received downstream from the optical fiber. For this purpose the analyzer will include an oscilloscope that is connected into the analyzer to generate an eye diagram of the received digital information signal. Using the eye diagram, an n-number of values from the received digital information signal that are respectively based on operational parameters of the VSB filter are determined. These values are then used to create a control signal input to the tapped delay equalizer for respectively weighting each of the n taps of the tapped delay equalizer, to thereby minimize impairments introduced into the received information signal. BRIEF DESCRIPTION OF THE DRAWINGS The novel features of this invention, as well as the invention itself, both as to its structure and its operation, will be best understood from the accompanying drawings, taken in conjunction with the accompanying description, in which similar reference characters refer to similar parts, and in which: FIG. 1 is a schematic presentation of a communications link for transmitting a digitally modulated signal over an optical fiber in accordance with the present invention; FIG. 2 is a schematic presentation of a driver/equalizer chip in accordance with the present invention, for use in the communications link shown in FIG. 1 ; FIG. 3A is an eye diagram of a digital output signal, when a digitally modulated input signal has been transmitted as an optical signal over a fiber optic, when no optical VSB filter is used in signal transmission; FIG. 3B is an eye diagram of a digital output signal, when a digitally modulated input signal has been transmitted as an optical signal over a fiber optic, when a VSB filter has been used in signal transmission; and FIG. 3C is an eye diagram of a digital output signal, when a digitally modulated input signal has been transmitted as an optical signal over a fiber optic, when the digitally modulated input signal has been equalized and an optical VSB filter has been used in signal transmission. DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring initially to FIG. 1 , a system for transmitting optical signals in accordance with the present invention is shown, and is generally designated 10 . As shown, the system includes a transmitter 12 and a receiver 14 that are interconnected with each other by an optical fiber 16 . FIG. 1 also shows that the system 10 includes an analyzer 18 which interconnects the receiver 14 with the transmitter 12 . In overview, a digitally modulated information signal 20 is provided as input to the system 10 for transmission over the optical fiber 16 from the transmitter 12 to the receiver 14 . As envisioned for the present invention the digitally modulated information signal 20 will have a predetermined symbol rate, R s , and it will have characteristics and parameters that are well known in the art. For the present invention, it is to be appreciated that the digitally modulated information signal 20 will experience several transformations as it passes through the system 10 . With this in mind, the general descriptor “information signal 20 ” is used in all references to the basic signal for all variations of the information signal 20 . In particular, these references include: 1) the original digitally modulated input information signal 20 ; 2) a digital (electrical) pre-transit equalized information signal 20 a; 3) an optical information signal 20 which is transmitted over the optical fiber 16 ; 4) a digital (electrical) post-transit information signal 20 b ; and 5) a digitally modulated output information signal 20 ′ which is received by a user of the system 10 . For reference purposes, these references for information signal 20 are all shown in FIG. 1 . As shown in FIG. 1 , the transmitter 12 includes a data mapper 22 (optional) which may be provided to handle and format the input information signal 20 for data transfer purposes. Also included in the transmitter 12 is a driver/equalizer chip 24 which is provided to equalize the input information signal 20 for maximum transmission efficiency through the system 10 . In accordance with the present invention, once the input information signal 20 has been equalized, the resulting pre-transit equalized information signal 20 a is converted into the optical information signal 20 by an Electrical/Optical (E/O) device 26 . Still referring to FIG. 1 , a vestigial sideband (VSB) filter 28 is provided with the transmitter 12 for filtering the optical information signal 20 . Once it is filtered, the optical information signal 20 is then passed to the optical fiber 16 for transmission over the optical fiber 16 to the receiver 14 . As is well known, the VSB filter 28 and the optical fiber 16 will introduce impairments to the optical information signal 20 during this transmission. In particular, the impairments will include phase delays in the optical information signal 20 , as well as group delays. Upon receipt of the optical information signal 20 at the receiver 14 , an Optical/Electrical (O/E) device 30 is provided to convert the optical information signal 20 into a digital, post-transit information signal 20 b . FIG. 1 shows that the post-transit information signal 20 b passes through a data slicer 32 where the data in signal 20 b can be appropriately narrowed. Also, a de-mapper 34 is provided, if necessary. Still referring to FIG. 1 , it will be seen that the post-transit information signal 20 b can also be passed from the O/E device 30 to the analyzer 18 . As envisioned for the present invention, the analyzer 18 will typically include an oscilloscope which presents the post-transit information signal 20 b as an eye diagram 36 (see FIGS. 3A, 3B ). The post-transit information signal 20 b is then passed back from the analyzer 18 to the driver/equalizer chip 24 of the transmitter 12 . FIG. 2 shows that the driver/equalizer chip 24 includes an n-number of taps 38 which each have a respective delay d t . Importantly, individual delays d t can be engineered for the driver/equalizer chip 24 as required for its particular application. Stated differently, d t may be equal to d t−1 , or it may not. Also included in the driver/equalizer chip 24 are an n-number of amplifiers 40 which are respectively connected with the same n-numbered taps 38 . Importantly, for an operation of the present invention, there must be an N-number of taps 38 per symbol in the digitally modulated input information signal 20 , where N is greater than 1. Thus, n (total number of taps 38 ) must be equal to, or greater than 1. As intended for the present invention, the analyzer 18 creates an eye diagram 36 which can be used to optimize a transmission of the optical information signal 20 over the optical fiber 16 . In particular, using the eye diagram 36 as a reference, an n-number of values are obtained from the post-transit information signal 20 b . The n-number of values which are obtained are then used by an equalizer control 42 in the driver/equalizer chip 24 . Specifically, the obtained values are used by the equalizer control 42 to establish amplitude control for the respectively numbered amplifiers 40 . FIG. 2 also indicates that a summer 44 in the driver/equalizer chip 24 sums the outputs of the n-number of amplifiers 40 . Also, a bias/gain control 46 is provided which, together with the summer 44 , create the pre-transit equalized information signal 20 a. In overview, the driver/equalizer chip 24 functions as a feedback control which operates to equalize the digitally modulated input information signal 20 for efficient transmission of the input information signal 20 from the transmitter 12 to the receiver 14 . Thus, at the receiver 14 , the post-transit information signal 20 b is received as a VSB filtered output information signal 20 ′ having a substantially same information content as the input information signal 20 . FIGS. 3A-C are provided to respectively show typical eye diagrams 36 a - c which are created by the analyzer 18 . As shown, FIG. 3A shows a post-transit information signal 20 b which has not been filtered by a VSB filter 28 . FIG. 3B shows a signal 20 b which has been filtered by a VSB filter 28 , but not equalized. And, FIG. 3C shows a signal 20 b which has been both filtered and equalized. As is well known by the skilled artisan, the eye diagram 36 c in FIG. 3C is preferable. While the particular Adaptive Equalization for Vestigial Sideband (VSB) Transmissions as herein shown and disclosed in detail is fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims.

The present invention pertains to systems and methods for equalizing a digitally modulated input signal for transmission as an optical signal over an optical fiber. In detail, this equalization is accomplished prior to the signal's conversion to an optical signal, and prior to the signal being filtered by a vestigial sideband (VSB) filter. In particular, equalization is accomplished by giving weights to the taps of a tapped delay equalizer, wherein weights for respective taps are derived from the output signal after its conversion to a digital signal at the downstream end of the optical fiber.

BACKGROUND OF THE INVENTION (1) Field of Invention This invention relates to light emitting devices, particularly to the package of such devices. (2) Brief Description of Related Art FIG. 1 shows a prior art package for a light emitting device. The light emitting device 10 is mounted over a metal plate 11 with an extension to serve as the lead of the bottom electrode of the device 10 . The top electrode of the device 10 is wire-bonded by wire 13 to a second metal plate 12 with an extension to serve as the lead for the top electrode of the device. The structure is sealed in transparent glue as shown in the side-view FIG. 2 for protection and improvement in reliability. The bottoms of the metal plates 11 , 12 can be soldered to a motherboard for surface-mounting. The drawback of the kind of package is that the package is fixed to the motherboard so the light can only be emitted in a direction perpendicular to the motherboard. Also, the package does not have heat-sinking provision. SUMMARY OF THE INVENTION An object of this invention is to provide a light emitting package capable of adjusting the direction of light emission. Another object of this invention is to provide a light emitting package capable of heat sinking. These objects are achieved by extending the leads of the package into pin-shaped forks or thin-plate shaped forks. The number of leads can be two or more than two. The leads can be bent to emit light a desired direction. One of the leads is coupled to a tab for heat sinking. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS FIG. 1 shows the top view a prior art surface-mount package for a light emitting device. FIG. 2 shows the side view of FIG. 1 . FIG. 3 shows the top-view of the basic fork-shaped leads of the present invention. FIG. 4 shows the side-view of FIG. 3 . FIG. 5 shows a top view of the package with two chips. FIG. 6 shows the top view of the package for a chip with two top electrodes. FIG. 7 shows the top view of the package for a chip with two bottom electrodes. FIG. 8 shows the top view of the package for two chips each with two bottom electrodes. FIG. 9 shows the package with the lead bent at right angle. FIG. 10 shows the package with the lead bent at acute angle. FIG. 11 shows the package with the lead folded. FIG. 12 shows the package with the zigzag lead. FIG. 13 shows the package with a focusing wall. FIG. 14 shows the package with a stepped focusing wall. FIG. 15 sows the package with a bevel focusing wall. FIG. 16 shows the package with a transparent cover. FIG. 17 shows the package with a transparent cover anchored in the stepped wall. FIG. 18 shows the package with light emitting device mounted on a heat sinking tab. FIG. 19 shows the package with one lead connected to the heat sinking tab. FIG. 20 shows the leads lying on the same plane. FIG. 21 shows the leads bent in different directions. FIG. 22 shows the two leads bent in the same direction and a third lead in opposite direction. DETAILED DESCRIPTION OF THE INVENTION FIG. 3 shows the basic structure of the present invention. A light emitting device chip 20 is mounted on metal substrate 22 . The electrodes of the chip are connected to pin-shaped leads 211 , 212 , 213 extending toward one side of the metal plate 22 . The middle lead 212 is continuous with the metal 22 , which is in contact with the bottom electrode of the chip 20 . The top electrode is wire-bonded-by wire 23 to the lead 211 . The lead 213 is unused. The chip, the bonding pads of the leads and the major portion of the metal plate 22 are sealed with transparent glue 25 to protect the combined structure and to stiffen leads 211 , 212 and 213 in position. The leads can be bent so the direction of the light emitted from the chip can be adjusted. The opposite side of the metal plate 22 is extended outside the seal 25 to form a tab with a mounting hole 26 , which can be clamped by a screw to a motherboard to serve as a heat sink. FIG. 4 shows the side view of FIG. 3, showing the chip 20 is wire-bonded to the lead 213 and sealed inside the glue 25 . FIG. 5 shows two chips 20 and 202 mounted on the metal plate 22 . The bottom electrodes of the chips 20 and 202 are both in contact with the common lead 212 . The top electrode of the chip 20 is wire-bonded by wire 23 to lead 211 . The top electrode of the chip 202 is wire-bonded by wire 232 to the lead 213 . FIG. 6 shows a chip 40 with two top electrodes. One top electrode is wire-bonded by wire 23 to lead 211 . The second top electrode is wire-bonded by wire 233 to the lead 212 . FIG. 7 shows a chip 30 with two bottom electrodes straddling over the two leads 211 and 212 . FIG. 8 shows two chips 30 and 302 each having two bottom electrodes. The chip 30 straddles over the leads 211 and 212 . The chip 301 straddles over the leads 212 and 213 . FIG. 9 shows how the end 241 of a lead 21 x as in FIG. 3 is bent in right angle to change the direction of light emission from the light emitting chip perpendicular to the motherboard, to which the leads are inserted. FIG. 10 shows the how the end 241 of lead 21 x is bent by an acute angle to change the direction of light emission from the light emitting chip at an acute angle with respect to the motherboard to which the leads are inserted. FIG. 11 shows the ends of the leads 21 x are folded at the end 243 . FIG. 12 shows a zigzag lead 21 x . The bend 27 increase the imbedded area of the lead 21 x in the, glue 25 , thereby strengthening the lead 21 x. FIG. 13 shows the glue 25 forming a cup 28 over and surrounding the light emitting chips. The cup window exposes the light emitting device without being imbedded in the glue, thereby allowing more light transmission. The wall 28 of the cup can have a step as shown in FIG. 14, which is the side-view of FIG. 13 . The wall 28 of the cup may be beveled to form a focusing cup as shown in FIG. 15 . FIG. 16 shows a transparent cover 45 mounted over the wall 28 of the cup 25 to protect the light emitting device. FIG. 17 shows a transparent cover 452 resting on the step of the wall shown in FIG. 14, and the glue 45 seals the structure outside the cover 452 . FIG. 18 shows a structure in which the metal tab 32 is separated from the lead 312 . The chip is mount on the metal tab 32 serving as one lead for the bottom electrode of chip 20 , and the top electrode of the chip 20 is wire-bonded by wire 23 to the lead 311 . The tab 32 also serves as a heat sink by clamping the tab to a motherboard with a screw through the hole 26 . FIG. 19 shows the metal tab 32 is continuous with a side lead 313 instead of a middle lead 312 shown in FIG. 3 . FIG. 20 shows all three leads 211 a, 212 a and 213 a are in parallel. FIG. 21 shows the three leads bent in different directions with leads 211 b and 213 b bent away from the middle lead 212 b. FIG. 22 shows two the leads 211 C and 212 C bent in one direction and the lead 213 C bent in an opposite direction. While the foregoing embodiments show only three leads, the number of leads is not limited to three leads. Two leads or more than three leads can be fabricated in a similar fashion. While the preferred embodiments of the invention have been described, it will be apparent to those skilled in the art that various modifications may be made in the embodiments without departing from the spirit of the present invention. Such modifications are all within the scope of this invention.

The leads of a light emitting device package are extended is flexible pins. These pins can be bent with respect to a motherboard so that the direction of the light entitled from the light emitting device can be adjusted. The package is tab-mounted to the motherboard for heat sinking or serving as a lead.

This application is a Divisional application of Ser. No. 08/207,609 filed Mar. 9, 1994, U.S. Pat. No. 5,536,585. BACKGROUND OF THE INVENTION The present invention relates to a magnetic recording medium and a fabrication method therefor. More in detail it relates to an improvement of an in-plane magnetic recording medium suitable for high-density magnetic recording. As a magnetic recording medium there is known a magnetic recording medium, in which a magnetic film is superposed on a non-magnetic substrate through an underlayer. A Co alloy is used for the magnetic film. The crystallographic structure of this Co alloy is a hexagonal close packed structure (hereinbelow abbreviated to h.c.p.) similarly to Co of simple substance, which has an easy magnetization axis in the direction of c-axis, i.e. [0001] axis. Consequently, in case where the Co alloy described above is used for the magnetic film for a high-density magnetic recording medium, it is necessary to direct the easy magnetization axis, i.e. c-axis, substantially in the plane of the magnetic film. That is, it is necessary that the easy magnetization axis is parallel to the direction, in which the magnetic film extends. In order that the easy magnetization axis is oriented parallelly to the magnetic film, there is known a method, by which an underlayer having a body centered cubic structure (hereinbelow abbreviated to b.c.c.) is disposed below the magnetic film. When this underlayer has a <100> orientation, the orientation of the magnetic film dispose thereon is <1120> and in this way the easy magnetization axis is oriented parallelly to the magnetic film. Concretely speaking, a construction of a high-density magnetic recording medium usable in practice at present is formed by superposing a Cr based metal layer on an A1 substrate, whose surface is covered by an NiP layer, by a well-known method as an underlayer and then by superposing a Co based magnetic film further thereon by a well-known method. In such a construction, since the underlayer has a substantially <100> orientation, the Co based magnetic film disposed thereon has a <1120< orientation and thus the easy magnetization axis is parallel to the surface of the magnetic film. U.S. Pat. No. 4,654,276, U.S. Pat. No. 4,652,499, U.S. Pat. No. 4,789,598 and U.S. Pat. No. 5,063,120 can be cited as literatures showing magnetic recording media having such a construction and these literatures are incorporated herein by reference. However, since the A1 substrate is soft, it may be deformed, when a strong impact is applied thereto from the exterior. Further, although it is required to smoothen further the surface of the substrate with recent increasing magnetic recording density and decreasing size of apparatus, softness of the substrate imposes a restriction thereon, when the surface thereof is polished so as to be smooth. Therefore it is conceived to form the substrate by using a hard and non-magnetic material such as glass and a magnetic recording medium provided with a glass substrate is disclosed e.g. in literatures described below: Literature: J. Appl. Phys. 67(9), 1 May (1990), pp. 4913-4915 and Literature: JP-A-Sho 63-106917. This publication discloses a medium so constructed that an underlayer made of Cr, Mo, Ti or Ta having a predetermined thickness is disposed on a glass substrate and a magnetic film made of Co, Ni, Cr and Pt, in which the content of Pt is 1 to 43 atom %, is formed further thereon. However, as far as the inventors know, such a magnetic recording medium provided with a glass substrate is inferior in magnetic characteristics to that having an A1/NiP substrate described previously and therefore it was not practical as a high-density magnetic recording medium. SUMMARY OF THE INVENTION The present invention has been done in view of the above description and one of the objects of the present invention is to provide a magnetic recording medium provided with a substrate made of a hard and non-magnetic material, which has excellent magnetic characteristics and is suitable for high-density magnetic recording, and a fabrication method therefor. Another object of the present invention is to provide a magnetic recording medium having excellent magnetic characteristics, independently from the material of the substrate, and a fabrication method therefor. According to an aspect of the present invention, the magnetic recording medium comprises a non-magnetic substrate, two underlayers disposed thereon directly or through some underlayer and a magnetic film disposed on these two underlayers and it is so constructed that the magnetic film has a hexagonal close packed structure, that the first underlayer, which is directly below the magnetic film, between the two underlayers has a body centered cubic structure, and that the second underlayer disposed directly below the first underlayer has an NaCl type crystallographic structure. FIG. 1 shows schematically an example of the magnetic recording medium, which will be explained below. A magnetic film 12 having an h.c.p. structure is formed on the first underlayer 13 having a b.c.c. structure. This first underlayer 13 is formed on the second underlayer 14 having an NaCl type crystallographic structure. The second underlayer is formed on a non-magnetic substrate 15 directly or through some underlayer. It is preferable that a protecting film 11 is formed on the magnetic film 12. It is preferable that the dominant orientation of the magnetic film is <1120> and that the dominant orientations of both the first and the second underlayer are <100>. Further both the first and the second underlayer are preferably made of non-magnetic materials. Furthermore the magnetic film is preferably made of Co or an alloy, whose main component is Co. Heretofore various sorts of alloys, whose main component is Co, have been used as magnetic films and such alloys can be used for realizing the present invention. Concretely speaking, Co based alloys containing at least one element among Cr, Ni, Fe, V, Ti, Zr, Hf, Mo, W, Ta, Re, Ru, Rh, Ir, Pt, Pd, Au, Ag, Cu, B, Al, C, Si, P and N are usable therefor. They are e.g. binary alloys such as Co--Cr, Co--Ni, Co--Fe, Co--V, Co--Mo, Co--Ta, Co--Re, Co--Pt, Co--Pd, etc. or ternary alloys, in which a third element is added to these binary alloys, such as Co--Cr--Ta, Co--Cr--Pt, Co--Cr--Mo, Co--Cr--W, Co--Cr--Re, Co--Ni--Zr, Co--Pt--Ta, Co--Pt--B, etc. or quarternary alloys, in which a fourth element is added thereto, such as Co--Cr--Ta--B, Co--Cr--Ta--Si, Co--Cr--Ta--C, Co--Cr--Ta--P, Co--Cr--Ta--N, Co--Cr--Pt--B, etc. Since in these alloys the content of Co is greatest and in addition the crystallographic structure thereof is h.c.p., they can be a Co based alloy magnetic film, which can be an object of the present invention. Further for the magnetic film not only a single layer but also a multi-layered film or a film having a compositional gradient in the film thickness direction can be used. The film thickness may be comprised between 2 nm and 100 nm, preferably between 5 nm and 50 nm. For forming the magnetic layer either one of radio frequency sputtering method, radio frequency magnetron sputtering method, DC sputtering method, DC magnetron sputtering method, ion beam sputtering method, ion beam plating method and physical vapor deposition method such as vacuum vapor deposition method may be used. At least one sort of material selected from the group consisting of Cr, Mo, W, V, Nb, Ta and alloys, whose main component is these elements, is preferably used as material for the first underlayer. It is a matter of course that the material for the first underlayer is not necessarily restricted to these materials, but other metals or alloys having the b.c.c. structure can be used therefor. It is preferable that the thickness of the first layer is comprised between 2 nm and 1 μm. From the economical point of view it is desirable that it is comprised between 2 and 200 nm. The first underlayer can be formed also by the physical vapor deposition method similarly to the magnetic film. Either one of MgO, CaO, TiO, VO, MnO, CoO, NiO and a mixed crystal, whose main component is these compounds, or either one of LiCl, NaCl, KCl and a mixed crystal, whose main component is these compounds, or either one of TiC, ZrC, HfC, NbC, TaC and a mixed crystal, whose main component is these compounds, may be suitably used as a material for the second underlayer. It is preferable that the thickness thereof is comprised between 10 nm and 100 μm. When it is smaller than 10 nm, it is difficult to intercept influences given by the base substrate on growth of the film having the b.c.c. structure, while when it is greater than 100 μm, time necessary for the formation of the film is too long and further undesirable phenomena such as enlargement of crystal grains in the oriented film, etc. take place. This second underlayer is formed also by the physical vapor deposition method such as the radio frequency magnetron sputtering method, etc. The substrate is made of a non-magnetic material and has a smooth surface. In view of increasing requirement of the impact resistant property and the smoothness of the surface, it is preferable that the substrate is made of glass such as soda lime glass, alumino-silicate glass, quartz glass, etc. or carbon. A substrate made of such a hard material, i.e. glass, is used in the present embodiment. It is a matter of course that the present invention doesn't exclude to use Al or Si for the material, of which the substrate is to be made. The shape of the substrate is not necessarily circular, but rectangular substrates will be used in some embodiments. The texture at the surface of the substrate will be explained later. When the magnetic film is made of Co or an alloy, whose main component is Co, the first underlayer is preferably made of Cr or an alloy, whose main component is Cr. Further, when the first underlayer is made of Cr or an alloy, whose main component is Cr, the second underlayer is preferably made of MgO, LiF or a mixed crystal, whose main component is these inorganic compounds. In the case where the c-axis of the magnetic film having the h.c.p. structure is to be oriented in the plane of the film, it can be thought that a low index crystallographic plane, which is to be parallel to the surface of the film, is a {1120} or {1100} plane. It is known that it is efficient to use an underlayer having a <100> oriented textured b.c.c. structure in order that the {1120} plane between them is parallel to the surface of the film. FIG. 3 shows a matching relation between the {1120} plane of the h.c.p. structure and the {100} plane of the b.c.c. structure. One of the alloys described previously is used for the non-magnetic underlayer having the b.c.c. structure and it is desirable to select one of them so that the interatomic distance in the {100} plane thereof is matched with the interatomic distance in the {1120} plane of the material, of which the magnetic film stated above is made. Concretely speaking, as understood from FIG. 3, they are so selected that Formula 1 and Formula 2 described below have values as close as possible. ##EQU1## where a(bcc) is a lattice constant for a-axis in the b.c.c. structure, c(hcp) is a lattice constant for c-axis in the h.c.p. structure, and a(hcp) is a lattice constant for a-axis in the h.c.p. structure. It is preferable that the difference between Formula 1 and Formula 2 is smaller than ±10% and it is more preferable that the difference is smaller than ±4%. However a b.c.c. crystal has generally a property that it is apt to be <110> oriented textured. For this reason it is not easy to have a dominant orientation of <100> while forming it directly on the substrate. Therefore, according to the present invention, orientation of the b.c.c. underlayer (first underlayer) is controlled by disposing the second underlayer having the NaCl type crystallographic structure directly below it. As indicated in FIG. 4, this utilizes the fact that the {100} plane of the b.c.c. structure is easily epitaxialy grown on the {100} plane of the NaCl type crystallographic structure. Further an NaCl type crystal has a property that it is generally easily <100> oriented textured. Consequently it is possible to obtain a film of sufficiently <100> oriented textured b.c.c. crystals by making b.c.c. crystals epitaxially grow on the surface thereof. The materials described previously are used for the non-magnetic underlayer having the NaCl type structure and particularly it is desirable to select them so that the interatomic distance in the {100} plane thereof is matched with the interatomic distance in the {100} plane of the first underlayer. Concretely speaking, as understood from FIG. 4, they are so selected that Formula 3 and Formula 4 described below have values as close as possible. ##EQU2## where a(bcc) has a meaning already explained and a(NaCl) is a lattice constant for a-axis in the NaCl type structure. It is preferable that the difference between Formula 3 and Formula 4 is smaller than ±20% and it is more preferable that the difference is smaller than ±5%. When the h.c.p. magnetic film is made epitaxially grow on the first b.c.c. underlayer, which is satisfactorily <100> oriented textured, a magnetic film, which is <1120> oriented textured and in which the easy magnetization axis of individual crystal grain is oriented in the plane of the film, is obtained. A magnetic film thus obtained exhibits a coercive force and a squareness ratio in in-plane direction, which are higher than those obtained in the where only the b.c.c. underlayer is formed on the substrate and the h.c.p. magnetic film is formed further thereon, and it can be used as an in-plane magnetic recording medium, by means of which data can be recorded and reproduced with a higher density. According to a second aspect of the present invention, not only easy magnetization axes of individual grains in the Co based alloy constituting the magnetic film can be made parallel to the film, but also they can be aligned. Preferably the easy magnetization axes are aligned in the recording direction. The magnetic recording medium according to the present aspect is also composed of a magnetic film, a first and a second underlayers, and a substrate, and materials and a method for forming them as well as the thickness thereof can be identical to those explained for the first aspect. Hereinbelow the present aspect will be explained more in detail. When a <100> single crystal film having an NaCl type crystallographic structure or a <100> oriented textured film, whose [100] orientation is controlled so as to be in a predetermined direction with respect to a substrate, is used as a substrate or an underlayer and an underlayer having a body centered cubic (bcc) structure is formed thereon, a single crystal layer or an oriented film, whose {100} plane is parallel to the substrate, is obtained. When a Co based alloy magnetic film having a hexagonal close packed (hcp) structure is formed on this film, a single crystal or an oriented magnetic film, whose {1120} plane is parallel to the substrate, is obtained. In this case, the [0001] axis, which is the easy magnetization axis of the magnetic film, is parallel to the substrate and when it is formed on the bcc <100> oriented film, the [0001] axis is controlled so as to be in a predetermined direction with respect to the substrate. Further, also when the Co based alloy magnetic film having the hcp structure is formed directly on a <100> single crystal having the NaCl type crystallographic structure or a <100> oriented film, the [0001] axis, which is the easy magnetization axis of the magnetic film, is parallel to the substrate. In the case where a film having the bcc structure is used, since it is possible to regulate the diameter of crystal grains and the distance between crystal grains in a state where the <100> orientation is maintained by controlling film forming conditions, the constructions described above have a feature that micro structure of the magnetic recording medium can be controlled and therefore they may be utilized, depending on the purpose of utilization. As a method for forming a <100> oriented textured film made of a material having the NaCl structure on a substrate serving as a base, it is possible e.g. to form microscopic unevenness called grating or texture on the substrate and to make the <100> oriented textured film grow thereon, using grapho-epitaxial crystal growth. The grapho-epitaxial crystal growth is described e.g. in "KOTAI BUTSURI (Solid Physics)" Vol. 20, No. 10 (1985), pp. 815˜820. If the grating or the texture is formed in concentric circles or in a spiral shape in a circumferential direction on a disk-shaped substrate, the [010] or [001] direction of the crystal having the NaCl structure is distributed also in concentric circles and as the result it is possible to align the easy magnetization axis of the Co based magnetic film. The easy magnetization axis [0001] of the Co based magnetic film having the hcp structure is parallel to a [011] or [011] direction of the bcc <100> oriented film. Since Co based alloy crystals having the hcp crystallographic structure, whose easy magnetization axes are perpendicular to each other, are grown mixedly on one <100> oriented crystal made of a material having the bcc structure, two sorts of easy magnetization axes in the circumferential and the radial direction exist mixedly. If microscopic unevenness is formed so that two sorts of patterns depict arcs in directions opposite to each other along the radial direction of the disk-shaped base substrate and that they intersect each other in crosshatch, it is possible to align approximately the <011> direction of the material crystal having the NaCl type crystallographic structure in the circumferential direction of the disk-shaped substrate. In this way it is possible to align the easy magnetization axes of the Co based alloy crystal having the hcp structure in two directions deviated by 45° from the circumferential direction towards the inner and the outer periphery. By using this method, it is possible to control the easy magnetization axis of the magnetic film so as to be parallel to the surface of the substrate and further to align the easy magnetization axis in a predetermined direction with respect to the circumferential direction for a disk-shaped substrate. In this way it can be aligned in the same direction as the recording direction at magnetic recording and as the result, characteristics of the in-plane magnetic recording medium can be improved. Since distribution of crystal grains in the magnetic film can be also controlled, it is possible to provide a magnetic medium suitable for a high-density magnetic recording. Furthermore, in the where the magnetic recording medium is used, combined with a magnetic head, taking it into account to realize a high track density, grooves or recesses may be disposed or non-magnetic regions or regions having different optical reflectivities may be formed on the magnetic recording medium fabricated by the method described above. FIG. 5 is a cross-sectional schematical diagram of a part of a disk-shaped magnetic disk according to a mode of realization of the present invention. The present invention will be explained below, referring to this figure. Unevenness consisting of recess portions 22 and protruding portions 23 as indicated in this cross-sectional diagram is formed in a surface portion of a disk-shaped non-magnetic substrate 21. It is preferable that they are so formed that the recess portions are larger than the protruding portions. When a material having the NaCl type structure is grown grapho-epitaxially thereon, an oriented film 24, whose surface has a {100} plane, is obtained on the recess portions. On the protruding portions, although the probability, with which crystals having the {100} plane are grown, is also high, crystals having other orientations can grow also thereon. It is useful that the orientation of the grating or the texture is aligned in the circumferential or radial direction of the disk. In this case, it is not always necessary that the grating or the texture is continuous over the whole periphery, but it may be interrupted. Any material having an NaCl type crystallographic structure has a tendency that a {100} plane develops. In a groove having a flat bottom as indicated in FIG. 5, the {100} plane is parallel to the bottom and in addition, since faces adjacent to walls of the protruding portions in the unevenness are also apt to be {100} planes, the <100> orientation of the NaCl type crystals is also defined with respect to the substrate. As indicated in FIG. 6A, if the grating has a concentric circular form, a spiral form or a similar form, <100> orientations of the crystals having the NaCl type crystallographic structure are distributed in concentric circles. On the other hand, as indicated in FIG. 6B, if 2 sorts of patterns are formed so that they depict arcs in directions opposite to each other along the radial direction of the disk-shaped base substrate and that they intersect each other in crosshatch, <110> orientations of the crystals having the NaCl type crystallographic structure can be distributed approximately in concentric circles. When a film having the bcc structure is formed on a film having such a structure, an oriented film 25, whose {100} plane is parallel to the base substrate, is grown owing to an epitaxial phenomenon. Then, when a Co based alloy magnetic film having the hcp structure is formed thereon, an oriented film 26, whose {1120} plane is parallel to the base substrate, is grown owing to the epitaxial phenomenon. Thus the easy magnetization axis [0001] of the magnetic film is parallel to the substrate, parallel to the <110> orientation of the bcc textured crystal, and parallel to the <100> orientation of the oriented crystals having the NaCl type crystallographic structure. That is, it is possible to control the direction of the easy magnetization axis of the magnetic film, depending on the direction of stripes of the grating or the texture and in particular the direction of perpendicular flanks of the protruding portions and directions of stripes of the grating or the texture indicated in FIGS. 6A and 6B give easy magnetization axis distributions desirable for the magnetic recording medium. The magnetic recording medium is obtained by forming a protecting film 27 thereon. The depth of the grating or the texture has influences on the size of individual crystal grains in the oriented film having the NaCl type crystallographic structure formed thereon and if film formation is effected under same conditions, smaller crystal grains are formed with smaller depth and smaller pitch in the unevenness. A region of preferable sizes of crystal grains of the material having the hcp structure constituting the magnetic film is comprised between 2 nm and 100 nm. In order to form such a magnetic film, the depth of the grating or the texture is preferably greater than 2 nm and smaller than 1 μ and it is desirable that the pitch is greater than 1 nm and smaller than 500 nm. If the pitch is smaller than 1 nm, the grapho-epitaxial growth hardly takes place. On the contrary, if it is greater than 500 nm, it is difficult to align the easy magnetization axis of the magnetic film in the circumferential direction of the disk. According to a third aspect of the invention of the present application, the underlayer is a single layer. Even if the material having the bcc crystallographic structure is omitted among the films constituting the magnetic recording medium described above, as indicated in FIG. 7, it is possible to obtain a magnetic recording medium, in which the easy magnetization axis of the magnetic film having the hcp structure made of a Co based alloy is parallel to the substrate and the distribution thereof is controlled with respect to the substrate similarly to that described above. FIG. 8 shows a case where a single-crystal substrate 31 having a {100} plane as a substrate surface, made of a material having the NaCl type crystallographic structure, is used. Since for the film having the bcc structure the {100} plane grows epitaxially and for the hcp structure the {1120} plane grows epitaxially, the easy magnetization axis is parallel to the substrate. Usually mismatch exists in the lattice constant between the substrate and the material having the bcc crystallographic structure. In order to alleviate this mismatch, sub-grain boundaries are formed on the films made of the materials having the bcc and the hcp crystallographic structure. It is possible to control the size of the crystal grains divided by these sub-grain boundaries so as to be in a region comprised between 5 and 100 nm, which is preferable for magnetic recording, by regulating conditions, under which the film is formed, e.g. temperature of the substrate and film formation speed. The surface of this substrate 31 can be also subjected to texture processing, as indicated in FIGS. 6A and 6B. FIG. 9 is a schematical diagram showing the cross-sectional construction of a magnetic recording medium constructed by forming a Co based alloy magnetic film having the hcp structure directly on the single-crystal substrate having the NaCl type crystallographic structure and the {100} plane, omitting the film made of a material having the bcc structure in FIG. 8. Also in this case the easy magnetization axis of the magnetic film is parallel to the substrate and effects similar to those obtained in the case indicated in FIG. 8 are obtained. The magnetic recording medium using a single-crystal substrate indicated in FIGS. 8 and 9 can be used for magnetic recording in the form of a disk-shaped magnetic disk. In this case, the direction of the easy magnetization axis in the magnetic recording medium with respect to the magnetic head varies, depending on the direction of the disk, which gives rise to variations e.g. in a reproduced output. However these are variations taking place with a period with respect to the crystallographic orientation and it is possible to correct them at recording and reproduction. Further, when a magnetic recording medium formed on a rectangular single-crystal substrate is combined with a magnetic head effecting a simple oscillation movement over the substrate, it can be used as a new magnetic recording system. When the magnetic recording medium is moved in a direction perpendicular to the movement of the magnetic head, data can be recorded on the rectangular magnetic recording medium and reproduced therefrom. Next a fourth aspect according to the invention of the present application will be explained. When using a <110> single-crystal or a <110> oriented film having an NaCl crystallographic structure as a substrate or an underlayer, an underlayer material having a body centered cubic (bcc) structure is formed thereon, a single-crystal or an oriented film, whose {211} plane is parallel to the substrate, is obtained. When a Co based alloy magnetic film having a hexagonal close packed (hcp) structure is formed on this film, a single-crystal or oriented magnetic film, whose {1100} is parallel to the substrate, is obtained. In this case the [0001] axis of the magnetic film, which is the easy magnetization axis, is parallel to the substrate. Also when the Co based alloy magnetic film having the hexagonal close packed (hcp) structure is formed directly on the <110> single-crystal or the <110> oriented film having the NaCl crystallographic structure, the [0001] axis of the magnetic film, which is the easy magnetization axis, is parallel to the substrate. In the case where a film having a bcc structure is used, since it is possible to regulate the diameter of crystal grains and the distance between crystal grains in a state where the <211> orientation is maintained by controlling film forming conditions, this construction has a feature that micro structure of the magnetic recording medium can be controlled and. therefore it may be utilized, depending on the purpose of utilization. As a method for forming a <110> oriented film made of a material having the NaCl structure on a substrate serving as a base, the grapho-epitaxial growth method described previously can be used. By using this method, it is possible to control the easy magnetization axis of the magnetic film so as to be parallel to the surface of the substrate and further to align the easy magnetization axis in a predetermined direction with respect to the circumferential direction for a disk-shaped substrate. In this way it can be aligned in the same direction as the recording direction at magnetic recording and as the result, characteristics of the in-plane magnetic recording medium can be improved. Since distribution of crystal grains in the magnetic film can be also controlled, it is possible to provide a magnetic medium suitable for a high-density magnetic recording. Furthermore, in case where the magnetic recording medium is used, combined with a magnetic head, taking it into account to realize a high track density, grooves or recesses may be disposed or non-magnetic regions or regions having different optical reflectivities may be formed on the magnetic recording medium fabricated by the method described above. FIG. 10 is a cross-sectional perspective view of a part of a disk-shaped magnetic disk according to a mode of realization of the present invention. This mode of realization will be explained, referring to this figure. V-shaped grating or texture 42 having e.g. an apex angle θ of about 90° is formed in a surface portion of a non-magnetic substrate 41, whose outer shape is a circle. When a material having the NaCl type crystallographic structure is grown grapho-epitaxially thereon as the second underlayer, an oriented film 43, whose surface is a {110} plane, is obtained. It is useful to align the direction of the grating or the texture in the circumferential direction of the disk. In this case, the grating or the texture is not necessarily continuous over the whole periphery, but it may be discontinuous. The material having the NaCl type crystallographic structure has a tendency that a {100} plane develops. If there is unevenness, whose apex angle is about 90° , as indicated in FIG. 10, the {100} plane grows parallelly to inclined surfaces. As the result, the surface of the film, which is parallel to the base substrate, is a {110} plane. Even if there are deviations in the apex angle by about 30° around 90° an oriented film having the NaCl type crystallographic structure, which has the {110} plane parallel to the base substrate, is obtained. Further, even if there are errors of about several tens of % in the depth of individual recess portions with respect to an average depth, a film having the NaCl type crystallographic structure, in which the {110} plane is dominant, can be obtained. In the case where it is desired that the surface of the film is flat, it is preferable to polish it after the grapho-epitaxial growth. The [001] direction of individual crystal grains in the oriented film having the NaCl type crystallographic structure is approximately parallel to the direction of stripes in the grating or the texture, i.e. parallel to the circumferential direction of the disk-shaped substrate. When a film having the bcc structure is formed on this film as the first underlayer, an oriented film 44, whose {211} plane is parallel to the base substrate, is grown by the epitaxial phenomenon. Then, when a Co based alloy magnetic film having the hcp structure is formed thereon, an oriented film 45, whose {1100} plane is parallel to the base substrate, is grown by the epitaxial phenomenon. In this way the easy magnetization axis [0001] of the magnetic film is parallel to the substrate and in addition it is approximately parallel to stripes of the grating or the texture, i.e. parallel to the circumferential direction of the disk-shaped substrate. Thus a magnetic recording medium is obtained by forming a protective film 46 thereon. The depth of the grating or the texture has influences on the size of individual crystal grains in the oriented film having the NaCl type crystallographic structure formed thereon and if the film is formed under a same condition, smaller crystal grains are formed with smaller depth. Desirable sizes of the crystal grains in the material having the hcp structure constituting the magnetic film are in a region comprised between 2 nm and 100 nm. For forming such a magnetic film it is preferable that the depth of the grating or the texture is greater than 1 nm and smaller than 200 nm. Further an average pitch of the protruding portions in the texture is preferably greater than 1 nm and smaller than 500 nm in the radial direction of the disk-shaped substrate. If the pitch is smaller than 1 nm, the grapho-epitaxial growth hardly takes place and on the other hand, if it is greater than 500 nm, it is difficult to align the easy magnetization axis of the magnetic film in the circumferential direction of the disk. FIG. 11 is a schematical diagram showing the cross-sectional construction of a magnetic recording medium constructed by forming a Co based alloy magnetic film having the hcp structure directly on the <110> oriented film having the NaCl type crystallographic structure, omitting the film 44 made of a material having the bcc structure from the construction indicated in FIG. 10. Also in this case the easy magnetization axis of the magnetic film 45' is parallel to the substrate and effects similar to those described above are obtained. FIG. 12 shows a case where dispersed grating or texture is formed on a non-magnetic substrate 51, in which a film 54 made of a material having the bcc crystallographic structure formed directly on the unevenness has a <211> orientation, while a Co based alloy magnetic film 55 having the hcp crystallographic structure exhibits a <1100> orientation. Further, since the easy magnetization of the magnetic film formed directly on the unevenness lies in the direction of the texture or the grating and crystal grains on the substrate are also distributed in that direction, preferable effects equivalent to those obtained in the cases described previously are obtained at magnetic recording. In this case, it is necessary that the distance between recess portions and protruding portions adjacent to each other is smaller than a fraction of the width of the magnetic recording defined by the width of track of a magnetic head. In order to achieve a magnetic recording density greater than 1 Gb/in2, it is preferably smaller than 100 nm. FIG. 13 is a schematical diagram showing the cross-sectional construction of a magnetic recording medium constructed by forming a Co based alloy magnetic film 55' having the hcp structure directly on the <110> oriented film 53 having the NaCl type crystallographic structure, omitting the film 54 made of a material having the bcc structure in FIG. 12. Also in this case the easy magnetization axis of the magnetic film is parallel to the substrate and effects similar to those obtained in the case indicated in FIG. 12 are obtained. FIG. 14 shows a case where a single-crystal substrate 61 made of a material having the NaCl crystallographic structure, in which the surface of the substrate is a {110} plane. Since a {211} plane grows epitaxially in the film 62 having the bcc structure and a {1100} plane grows epitaxially in the film 63 having the hcp structure, the easy magnetization axis is parallel to the substrate. Mismatch exists usually in the lattice constant between the substrate and the material having the bcc crystallographic structure. In order to alleviate this mismatch, sub-grain boundaries are formed on the films made of materials having the bcc and the hcp crystallographic structure. It is possible to control the size of the crystal grains divided by these sub-grain boundaries so as to be in a region comprised between 5 and 100 nm, which is preferable for magnetic recording, by regulating conditions, under which the film is formed, e.g. temperature of the substrate and film formation speed. The surface of this substrate 61 can be subjected to texture processing, as indicated in FIG. 10 or FIG. 12. FIG. 15 is a schematical diagram showing the cross-sectional construction of a magnetic recording medium constructed by forming a Co based alloy magnetic film 63' having the hcp structure directly on the (110) oriented single-crystal substrate 61 having the NaCl type crystallographic structure, omitting the film 62 made of a material having the bcc structure in FIG. 14. Also in this case the easy magnetization axis of the magnetic film is parallel to the substrate and effects similar to those obtained in the case indicated in FIG. 12 are obtained. The magnetic recording medium using a single-crystal substrate indicated in FIGS. 14 and 15 can be used for magnetic recording in the form of a disk-shaped magnetic disk. In this case, the direction of the easy magnetization axis in the magnetic recording medium with respect to the magnetic head varies, depending on the direction of the disk, which gives rise to variations e.g. in a reproduced output. However these are variations taking place with a period with respect to the crystallographic orientation and it is possible to correct them at recording and reproduction. Further, when a magnetic recording medium formed on a rectangular single-crystal substrate is combined with a magnetic head effecting a simple oscillation movement over the substrate, it can be used as a new magnetic recording system. When the magnetic recording medium is moved in a direction perpendicular to the movement of the magnetic head, data can be recorded on the rectangular magnetic recording medium and reproduced therefrom. Another aspect of the present invention indicates a new combination of a substrate made of a hard non-magnetic material such as glass, etc. with an underlayer. A construction, in which a layer made of an NaCl type crystal material is superposed on a glass substrate as a second underlayer, as indicated by an embodiment, has not been known heretofore. Still another aspect of the present invention consists in that a plane defining the direction of the crystal growth in the underlayer is formed on a surface of a substrate. For example, a second underlayer 24 grows along a side surface of a protruding portion 23 in FIG. 5. If there is not such a surface defining the direction of the crystal growth, although the direction of the orientation of individual crystal grains in the underlayer is defined, (a crystal, whose surface is a {100} plane, grows in FIG. 5), the direction of oriented planes is diverged (the direction [010] or [001] of the crystal is irregular). Therefore, although the easy magnetization axis 71 of the magnetic film is parallel to the magnetic film, the direction thereof is diverged, as indicated in FIG. 16A. On the other hand, if there are faces 73 and 75 defining crystals, as indicated in FIG. 16B, since crystals grow along the faces, the direction of easy magnetization axes is determined according to a certain rule. In certain cases, crystals having easy magnetization axes parallel to the faces 73 and 75 and crystals having easy magnetization axes perpendicular to those faces can exist mixedly. The state indicated in FIG. 16B has a magnetic anisotropy greater than that obtained in the state indicated in FIG. 16A and from the point of view of magnetic characteristics it can be said that the former is more excellent than the latter. Further the size of crystal grains grown between the faces 73 and 75 can be kept approximately constant by keeping the distance therebetween constant, as indicated in FIG. 16B. Therefore, since the size of crystal grains in the magnetic film is kept constant, directions of easy magnetization axes are aligned, and divergence thereof among different crystal grains is small, it is possible to obtain properties of matter desirable as a magnetic recording medium. BRIEF DESCRIPTION OF THE DRAWINGS These and other objects and technical advantages of the present invention will be readily apparent from the following description of the preferred exemplary embodiments of the invention in conjunction with the accompanying drawings, in which: FIG. 1 is a cross-sectional view showing a fundamental construction of a magnetic recording medium according to the present invention; FIGS. 2A and 2B are perspective views indicating planes parallel to the c-axis in an h.c.p. structure; FIG. 3 is a plan view indicating a matching relation between a {1120} plane in an h.c.p. structure and a {100} plane in a b.c.c. structure; FIG. 4 is a plan view indicating a matching relation between a {100} plane in a b.c.c. structure and a {100} plane in an NaCl type structure; FIG. 5 is a schematical diagram showing cross-sectional construction of a magnetic recording medium according to Embodiment 5 of the present invention; FIGS. 6A and 6B are diagrams for explaining configuration of grating formed in a surface portion of a substrate; FIG. 7 is a schematical diagram showing cross-sectional construction of a magnetic recording medium according to Embodiment 6 of the present invention; FIG. 8 is a cross-sectional view of a magnetic recording medium according to Embodiment 8 of the present invention; FIG. 9 is a cross-sectional view of a magnetic recording medium according to Embodiment 9 of the present invention; FIG. 10 is a schematical diagram showing cross-sectional construction of a magnetic recording medium according to Embodiment 12 of the present invention; FIG. 11 iS a schematical diagram showing cross-sectional construction of a magnetic recording medium according to Embodiment 13 of the present invention; FIG. 12 is a cross-sectional view of a magnetic recording medium according to Embodiment 14 of the present invention; FIG. 13 is a cross-sectional view of a magnetic recording medium according to Embodiment 15 of the present invention; FIG. 14 is a cross-sectional view of a magnetic recording medium according to Embodiment 16 of the present invention; FIG. 15 is a cross-sectional view of a magnetic recording medium according to Embodiment 17 of the present invention; FIGS. 16A and 16B are diagrams indicating directions of easy magnetization axes in a magnetic film; FIG. 17 is a cross-sectional view of a magnetic recording medium according to Embodiment 1 of the present invention; FIG. 18 is a cross-sectional view of a magnetic recording medium according to Embodiment 2 of the present invention; FIG. 19 is a schematical diagram showing an embodiment of a magnetic recording apparatus according to the present invention; FIG. 20 is a diagram indicating the construction of a magnetic recording apparatus according to Embodiment 10 of the present invention; FIG. 21 is a schematical diagram showing a cross-sectional construction of a magnetic recording medium according to Embodiment 11 of the present invention; FIG. 22 is a diagram showing the construction of a magnetic recording apparatus according to Embodiment 18 of the present invention; and FIG. 23 is a schematical diagram showing a cross-sectional construction of a magnetic recording medium according to Embodiment 19 of the present invention; DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinbelow several embodiments of the present invention will be explained, referring to the drawings. <Embodiment 1> Using a glass substrate having a diameter of 3.5 inches, a magnetic recording medium having a cross-sectional construction as indicated in FIG. 17 was fabricated by the radio frequency magnetron sputtering method. MgO underlayers 84, 84'; Cr underlayers 83, 83'; Co alloy magnetic films 82, 82'; and carbon protective films 81, 81' are formed in this order on two surfaces of the glass substrate 85. The MgO underlayers 84, 84' have an NaCl type crystallographic structure, while the Cr underlayers 83, 83' have a b.c.c. structure and the Co alloy magnetic films 82, 82' have an h.c.p. structure. The MgO underlayers 84, 84' were formed by using an argon/oxygen mixed gas having a mixing ratio of 9/1 under a condition that the pressure of the gas was 0.5˜1.5 Pa, the temperature of the substrate-was 300° C. and the speed of the film formation was 3˜5 nm per minute The Cr underlayers 83, 83' the Co alloy magnetic films 82, 82'; and the carbon protective films 81, 81' were formed by using argon gas under a condition that the pressure of the gas was 0.7 Pa, the temperature of the substrate was 150° C. and the speed of the film formation was 50 nm per minute. The composition of a target used for forming the magnetic films 82, 82' was Co-15 at. % Cr-8 at. % Pt. Concerning the thickness of the various films, the MgO underlayers were 50 nm thick, the Cr underlayers were 50 nm thick, the Co alloy magnetic films were 30 nm thick, and the carbon protective films were 10 nm thick. The formation of all the films described above was effected continuously in a same vacuum chamber without breaking vacuum. Crystallographic orientation and magnetic characteristics of a sample thus prepared were measured by X-ray diffraction and by using a vibrating sample magnetometer (VSM), respectively. Compared with a magnetic recording medium prepared without MgO under-layers layers under otherwise completely identical conditions, both the <100> orientation of the Cr underlayers and the <1120> orientation of the Co alloy magnetic films were remarkably improved. The coercive force in the in-plane direction of the film was increased by 9.3% (140 Oe) and the squareness ratio is increased by 11% (0.09). The difference between Formula 1 and Formula 2 described previously calculated from the respective crystallographic structures of the Co alloy magnetic film, the Cr underlayer and the MgO underlayer in this magnetic recording medium is -3.8% and the difference between Formula 3 and Formula 4 is -3.2%. <Embodiment 2> Using a glass substrate having a diameter of 3.5 inches, a magnetic recording medium having a cross-sectional construction as indicated in FIG. 18 was fabricated by the radio frequency magnetron sputtering method. LiF underlayers 94, 94'; Cr underlayers 93, 93'; Co alloy magnetic films 92, 92'; and carbon protective films 91, 91' are formed in this order on two surfaces of the glass substrate 95. The LiF underlayers 94, 94' have an NaCl type crystallographic structure, while the Cr underlayers 93, 93' have a b.c.c. structure and the Co alloy magnetic films 92, 92' have an h.c.p. structure. The LiF underlayers 94, 94' were formed by using argon gas under a condition that the pressure of the gas was 0.5˜1.5 Pa, the temperature of the substrate was 300° C. and the speed of the film formation was 3˜5 nm per minute. The Cr underlayers 93, 93', the Co alloy magnetic films 92, 92'; and the carbon protective films 91, 91' were formed under the same condition as that used in Embodiment 1. The composition of a target used for forming the magnetic films 92, 92' was Co-12 at. % Cr-2 at. % Pt. Concerning the thickness of the various films, the LiF underlayers were 50 nm thick, the Cr underlayers were 50 nm thick, the Co alloy magnetic films were 30 nm thick, and the carbon protective films were 10 nm thick. The formation of all the films described above was effected continuously in a same vacuum chamber without breaking vacuum. Crystallographic orientation and magnetic characteristics of a sample thus prepared were measured by X-ray diffraction and by using a vibrating sample magnetometer (VSM), respectively. As the result, for the magnetic recording medium in the present embodiment, compared with a magnetic recording medium prepared without LiF underlayers under otherwise completely identical conditions, both the <100> orientation of the Cr underlayers and the <1120> orientation of the Co alloy magnetic films were remarkably improved. The coercive force in the in-plane direction was increased by 12% (130 Oe) and the squareness ratio was increased by 9.9% (0.08). Further magnetic recording media completely identical to that obtained in the embodiment described above, except that V, Mo, W or Cr-3 at. % Si alloy was used in lieu of the Cr underlayers, were fabricated. Also for these magnetic recording media, compared with respective examples for comparison, in which no LiF underlayers were disposed, it was verified that both the <100> orientation of the b.c.c. underlayers and the <1120> orientation of the Co alloy magnetic films were remarkably improved. The coercive force and the squareness ratio were also increased. These results are indicated in TABLE 1. TABLE 1__________________________________________________________________________ INCRE- INCRE- MENT IN COER- MENT IN SQUARE- FIRST SECOND SIVE COERSIVE SQUARE- NESS UNDER- UNDER- FORCE FORCE NESS RATIO LAYER LAYER (Oe) (%) RATIO (%)__________________________________________________________________________EXAMPLE Cr NON 1150 -- 0.81 --FORCOMPARISONPRESENT Cr LiF 1280 12 0.89 9.9INVENTIONEXAMPLE V NONE 1120 -- 0.80 --FORCOMPARISONPRESENT V LiF 1220 8.9 0.86 7.5INVENTIONEXAMPLE Mo NONE 1100 -- 0.78 --FORCOMPARISONPRESENT Mo LiF 1190 8.2 0.85 9.0INVENTIONEXAMPLE W NONE 1110 -- 0.80 --FORCOMPARISONPRESENT W LiF 1170 5.4 0.84 5.0INVENTIONEXAMPLE Cr--Si NON 1160 -- 0.80 --FORCOMPARISONPRESENT Cr--Si LiF 1270 9.5 0.88 10INVENTION__________________________________________________________________________ Furthermore also for magnetic recording media, in which Nb, Ta, Cr-5 at. % Nb alloy or Cr-10 at. % Mo alloy was used for the first underlayer, compared with respective examples for comparison, in which no LiF underlayers were disposed, it was confirmed that both the orientation and the magnetic characteristics were improved. <Embodiment 3> Using a glass substrate having a diameter of 3.5 inches, a magnetic recording medium having a cross-sectional construction as indicated in FIG. 18, similarly to that described in Embodiment 2, was fabricated by the radio frequency magnetron sputtering method. LiF underlayers 94, 94'; Cr underlayers 93, 93'; Co alloy magnetic films 92, 92'; and carbon protective films 91, 91' are formed in this order on two surfaces of the glass substrate 95. The LiF underlayers 94, 94' were formed by using argon gas under a condition that the pressure of the gas was 0.5˜1.5 Pa, the temperature of the substrate was 300° C. and the speed of the film formation was 3˜5 nm per minute The Cr underlayers 93, 93' the Co alloy magnetic films 92, 92'; and the carbon protective films 91, 91' were formed under the same condition as that used in Embodiment 1. The composition of a target used for forming the magnetic films 92, 92' was Co-18 at. % Cr-6 at. % Pt in the present embodiment. Concerning the thickness of the various films, the LiF underlayers were 50 nm thick, the Cr underlayers were 50 nm thick, the Co alloy magnetic films were 30 nm thick, and the carbon protective films were 10 nm thick. The formation of all the films described above was effected continuously in a same vacuum chamber without breaking vacuum. Further magnetic recording media, in which NaF, TiC, VC and TiN having same NaCl type crystallographic structures were used in lieu of the LiF underlayers, were fabricated under conditions similar to those described previously. Crystallographic orientation and magnetic characteristics of samples thus prepared were measured by X-ray diffraction and by using a vibrating sample magnetometer (VSM), respectively. As the result, for all the magnetic recording media in the present embodiment, compared with a magnetic recording medium prepared without underlayers having the NaCl type crystallographic structure under otherwise completely identical conditions, both the <100> orientation of the Cr underlayers and the <1120> orientation of the Co alloy magnetic films were remarkably improved and increase in the coercive force in the in-plane direction and the squareness ratio was confirmed. These results are indicated in TABLE 2. TABLE 2__________________________________________________________________________ INCRE- INCRE- MENT IN COER- MENT IN SQUARE- FIRST SECOND SIVE COERSIVE SQUARE- NESS UNDER- UNDER- FORCE FORCE NESS RATIO LAYER LAYER (Oe) (%) RATIO (%)__________________________________________________________________________EXAMPLE Cr NON 1350 -- 0.80 --FORCOMPARISONPRESENT Cr LiF 1500 11 0.88 10INVENTION Cr NaF 1380 2.2 0.81 1.3 Cr TiC 1410 4.4 0.85 6.3 Cr VC 1450 7.4 0.84 5.0 Cr TiN 1390 3.0 0.82 2.5__________________________________________________________________________ Further magnetic recording media, in which KBr, RbI, HfC, NbC, TaC, VN, ZrN, ZrC, (Ti, V)C, or mixed crystals, whose main component was these inorganic compounds, was used for the second underlayer, were prepared. It was confirmed that similar effects can be obtained also for these magnetic recording media. <Embodiment 4> FIG. 19 is a schematic diagram of an embodiment of a magnetic recording apparatus. Magnetic recording media 101 are held by a holder rotated by a motor and a composite head 102 using magneto-resistive effect sensor for writing-in and reading-out information is disposed so that each of them corresponds to each of magnetic films. The composite head 102 using magneto-resistive effect sensors is moved by an actuator 103 and a voice coil motor 104 with respect to the magnetic recording medium 102. Further there are disposed a recording/reproducing circuit 105, a positioning circuit 106 and an interface control circuit 107 for controlling them. When the magnetic recording mediums fabricated in the different embodiments were used to be applied to this magnetic recording apparatus, for all the-cases it was possible to record data at a high S/N ratio and a high density. According to Embodiments 1 to 3, it was possible to provide a magnetic recording medium having an increased coercive force in the in-plane direction and squareness ratio, which is suitable for magnetic recording at a higher density. Further it was possible to provide a magnetic recording apparatus capable of high-density recording at a high S/N ratio. <Embodiment 5> Concentric grating having a depth of 50 nm and a pitch of 100 nm was formed in a surface portion of a quartz glass substrate 21 having a diameter of 1.8 inches by using photoresist, as indicated in FIG. 5. Protruding portions 23 were 20 nm wide, while recess portions 22 were 80 nm wide. A magnetic recording medium was fabricated by a process indicated below by using this substrate. An LiF film 24 100 nm thick having an NaCl structure was formed by the radio frequency sputtering method, while keeping the substrate 21 at a high temperature. After the formation of the film, it was subjected to heat treatment in an electric oven, kept in an inert gas atmosphere. The LiF film was examined by the X-ray diffraction method. As the result, it was confirmed that the LiF film was an oriented polycrystalline film, whose {100} plane was approximately parallel to the substrate and further that the [001] orientation of crystal grains was distributed approximately concentrically. Micro structure of the LiF film was examined by means of a scanning electron microscope and it was verified that it was composed of crystal grains having grain sizes between 50 nm and 100 nm and further that there existed unevenness of 30 to 100 nm. on the surface. After having polished the surface so as to be flat, a Cr film 25 50 nm thick having a bcc crystallographic structure and a Co--Cr--Pt film 26 30 nm thick having an hcp crystallographic structure were formed thereon by the radio frequency magnetron sputtering method. A Co-18 at % Cr-6 at % Pt target was used for forming the magnetic film. The temperature of the substrate was 400° C. at the formation of the Cr film and 180° C. at the formation of the Co--Cr--Pt magnetic film. The Ar gas pressure at sputtering was 10 mTorr and sputter power was 6 W/cm 2 . Further a carbon film 10 nm thick was formed as a protective film 27 to fabricate the magnetic recording medium. The structure of the film was examined by the X-ray diffraction and it was confirmed that the Cr film was a <100> oriented polycrystalline film, while the Co--Cr--Pt film was a <1120> oriented polycrystalline film. Magnetic recording media were fabricated under the same conditions as described above, using V, Nb, Mo, Cr-5 at % Ti, Cr-2 at % Zr, Cr-20 at % V and Cr-1 at % B in lieu of Cr. As the result, it was confirmed by the X-ray diffraction method that structures similar to those described above were realized both for the underlayer having the bcc structure and the magnetic film having the hcp structure. A magnetic recording medium was fabricated as a sample for comparison, in which the Cr film, the Co--Cr--Pt magnetic film and the C protective film were formed under the same conditions as described above directly on a quartz glass substrate on which no grating was formed. As a result of X-ray diffraction it was confirmed that the Cr film exhibited configuration, in which two sorts of orientations, i.e. <100> and <110>, were mixed, that in the magnetic film there existed mixedly crystal grains, whose easy magnetization axis was parallel to the substrate, and crystal grains, whose easy magnetization axis was inclined by about 30° with respect to the substrate, and that directions of the easy magnetization axis were distributed irregularly in the plane of the substrate. Evaluation of recording/reproduction characteristics of these magnetic recording media was effected by means of a thin film magnetic head. The magnetic head had a track width of 5 μm and a gap length of 0.2 μm. The distance between the magnetic head and the magnetic recording medium at measurement was 0.06 μm and the relative speed therebetween was 10 m/s. Recording density characteristics, S/N ratio and off-track characteristics were chosen as evaluation items. The recording density characteristics were measured as a half output recording density (D 50 ), at which a low frequency reproduced output is decreased to a half; the S/N ratio was measured as a relative value on the basis of an S/N ratio obtained for the sample for comparison; and the off-track characteristics were measured as a relative value of the magnetization spread out beyond the recorded track edge, compared with that obtained for the sample for comparison. Increasing value of the S/N ratio and decreasing value of the off-track characteristics indicate that they are more suitable for high-density magnetic recording. From TABLE 3 it was verified that the magnetic recording medium according to the present embodiment is improved in all the recording density characteristics, the S/N ratio and the off-track characteristics with respect to the example for comparison and that it has characteristics desirable for a high density magnetic recording medium. Experiments were effected also by using a <100> oriented film made of either one of LiCl, NaCl, KCl, MgO, CaO, TiO, VO, MnO, CoO, NiO, TiC, ZrC, HfC, NbC and TaC in lieu of LiF as a material having the NaCl type crystallographic structure. When a different material is used, the condition for the grapho-epitaxial growth varies. Thus it was necessary to select a film forming method suitable for a certain material or conditions such as substrate temperature at the film formation, heat treatment after the film formation, etc. However it was confirmed that in all the cases where these <100> oriented films are used, they have characteristics desirable for a high-density magnetic recording medium, which are similar to those described previously. TABLE 3__________________________________________________________________________ EXAMPLE FOR COM- PARISON EMBODIMENT 5__________________________________________________________________________NaCl STRUC- NONE <100>TURE FILMbcc STRUC- Cr Cr V Mb Mo Cr--Ti Cr--Zr Cr--V Cr--BTURE FILMRECORDING 65 82 80 73 70 86 82 79 84DENSITY(D.sub.50 (kFCI)S/N RATION 1 1.6 1.5 1.2 1.5 1.7 1.8 1.4 1.4(RELATIVEVALUE)OFF-TRACK 1 0.7 0.7 0.8 0.7 0.5 0.5 0.6 0.5CHARACTE-RISTICS(RELATIVEVALUE)__________________________________________________________________________ <Embodiment 6> An oriented film 24 having the NaCl structure, an oriented film 26' having the hcp structure and a protective film 27 were formed one after another on a surface of a quartz glass substrate 21 having a diameter of 1.8 inches, in a surface portion of which concentric grating having a depth of 50 nm and a pitch of 100 nm was formed by a process similar to that described previously in Embodiment 5, except that the film formation using the material having the bcc crystallographic structure was omitted, to fabricate a magnetic recording medium having the structure indicated in FIG. 7. For the magnetic film a binary alloy selected from the group consisting of Co-18 at % Cr, Co-12 at Ni, Co-18 at % Fe, Co-20 at % V, Co-20 at % Mo, Co-16 at % Ta, Co-20 at % Re, Co-16 at % Pt and Co-15 at % Pd; a ternary alloy selected from the group consisting of Co-18 at % Cr-2 at % Ta, Co-21 at % Cr-3 at % Mo, Co-19 at % Cr-1.5 at % W, Co-15 at Cr-7 at % Re, Co-14 at % Ni-1 at % Zr, Co-16 at % Pt-2 at % Ta, and Co-18 at % Pt-0.8 at % B; or a quarternary alloy selected from the group consisting of Co-18 at % Cr-2 at % Ta-2 at % B, Co-20 at % Cr-1.5 at % Ta-0.3 at % Si, Co-19 at % Cr-2.5 at % Ta-0.8 at % C, Co-22 at % Cr-1.6 at Ta-0.2 at % P, Co-21 at % Cr-1 at % Ta-0.2 at N, Co-12 at % Cr-8 at % Pt-0.7 at % B, was used. Magnetic recording media were prepared for samples for comparison, in each of which a Cr film 50 nm thick serving as an underlayer was formed on a flat quartz glass substrate, then one of the magnetic films described above was formed thereon, and finally a C protective film was formed further thereon. Linear densities (D 50 : kFCI) among recording/reproduction characteristics of magnetic recording media obtained by using <100> oriented films of NiO as the material having the NaCl crystallographic structure were as indicated in TABLE 4. For the S/N ratio and the off-track characteristics other than the linear density, it was verified that characteristics of the magnetic recording media according to the present embodiment were improved by more than 10% with respect to samples for comparison having magnetic films of same compositions formed by using prior art Cr underlayers and that they were therefore excellent as high density magnetic recording media. Also in case where the magnetic films were formed on <100> oriented films having the NaCl crystallographic structure other than NiO, similar improvement effects were recognized. TABLE 4__________________________________________________________________________MAGNETIC EXAMPLE FORFILM COMPARISON EMBODIMENT 6__________________________________________________________________________ NaCl NONE <100> ORIENTED STRUCTURE NiO FILM FILM bcc Cr NONE STRUCTURE FILMCo--Cr 62 80Co--Ni 58 76Co--Fe 56 71Co--V 60 75Co--Mo 58 70Co--Ta 50 73Co--Re 48 72Co--Pt 56 70Co--Pd 55 69Co--Cr--Ta 65 82Co--Cr--Pt 64 85Co--Cr--Mo 61 81Co--Cr--W 58 78Co--Cr--Re 62 80Co--Ni--Zr 62 81Co--Pt--Ta 63 85Co--Pt--B 66 83Co--Cr--Ta--B 66 90Co--Cr--Ta--Si 65 89Co--Cr--Ta--C 64 80Co--Cr--Ta--P 60 83Co--Cr--Ta--N 62 82Co--Cr--Pt--B 63 88__________________________________________________________________________ <Embodiment 7> A groove, in which the protruding portion was 30 nm wide and the recess portion was 100 nm wide and 20 nm deep, was formed in a spiral form by the photolithographic method in a surface portion of a glass substrate having a diameter of 1.8 inches. A magnetic recording medium was prepared by a process described below, using this substrate. A KCl film 50 nm thick was formed on the substrate by the radio frequency sputtering method. After the formation of the film, it was subjected to heat treatment in an electric oven kept in an gas atmosphere containing water vapor. The KCl film was examined by the X-ray diffraction method. As the result, it was verified that the KCl film was an oriented polycrystalline film, whose {100} plane was approximately parallel to the substrate. It was confirmed further that crystal grains were distributed approximately concentrically. Micro structure of the KCl film was examined by means of a scanning electron microscope and it was verified that it consisted of crystal grains having grain sizes of 30 to 100 nm and further that there existed unevenness of 20 to 50 nm on the surface. After having polished the surface so as to be flat, a Cr-2 at % Zr film 50 nm thick having a bcc crystallographic structure and a Co--Cr--Ta film 20 nm thick having an hcp crystallographic structure were formed thereon by the radio frequency magnetron sputtering method. A Co-18 at % Cr-3 at % Ta target was used for forming the magnetic film. The temperature of the substrate was 300° C. at the formation of the Cr film and 150° C. at the formation of the Co--Cr--Pt magnetic film. The Ar gas pressure at sputtering was 3 to 10 mTorr and sputter power was 6 to 10 W/cm 2 . Further a carbon film 10 nm thick was formed as a protective film to fabricate the magnetic recording medium. The structure of the film was examined by the X-ray diffraction and it was confirmed that the Cr film had a strong 200 diffraction line and thus it was a <100> oriented textured film, while the Co--Cr--Ta film was a <1120> oriented textured polycrystalline film. A magnetic recording medium was fabricated by the same method as described above, in which a Co--Cr--Ta magnetic film was formed directly on the KCl film without forming the Cr--Zr film having the bcc crystallographic structure and a C protective film was formed further thereon. A magnetic recording medium was fabricated as a sample for comparison, in which the Cr--Zr film, the Co--Cr--Ta film and the C protective film were formed directly on a flat quartz glass substrate. Recording/reproduction characteristics were compared under conditions similar to those used in Embodiment 5. As a result it was confirmed that all the magnetic recording media according to the present invention, in which the KCl film exhibiting the <100> dominant orientation was disposed, were better by 25% in the linear density, by 40% in the S/N ratio and by 32% in the off-track characteristics than the sample for comparison. Further, also in case where LiCl, NaCl or LiF was used as another material instead of the KCl film, similar desirable effects were confirmed. <Embodiment 8> A magnetic recording medium having a construction indicated in FIG. 8 was fabricated by a process described below, using a rectangular [100]MgO single-crystal 31, whose one side was 20 mm long, as a substrate. A V film 32 30 nm thick having a bcc crystallographic structure and a Co--Cr--Ta--Si film 33 15 nm thick having an hcp crystallographic structure were formed thereon by the radio frequency magnetron sputtering method. A Co-19 at % Cr-2 at % Ta-2 at Si target was used for forming the magnetic film. The temperature of the substrate was 450° C. at the formation of the V film and 150° C. at the formation of the Co--Cr --Ta--Si magnetic film. The Ar gas pressure at sputtering was 3 mTorr and sputter power was 10 W/cm 2 . Further a boron film 34 10 nm thick was formed as a protective film to fabricate the magnetic recording medium. The structure of the film was examined by the X-ray diffraction and it was confirmed that the V film grew epitaxially so that the {100} plane was parallel to the substrate and that the Co--Cr--Ta--Si film grew epitaxially so that the {1120} plane was parallel to the substrate. The structure of the magnetic recording medium was examined by means of a transmission-electron microscope and it was found that sub-grain boundary existed in the magnetic film and that crystal grains divided by this sub-grain boundary had inclinations comprised between 0.3°and 1°. The average size of the crystal grains was 48 nm. Further the composition of the interior of the crystal grains was also examined and it was found that Cr and Si were segregated in the neighborhood of the sub-grain boundary. This magnetic recording medium had two sorts of easy magnetization axes, which were perpendicular to each other, and this direction corresponded to <001> of the [100] MgO substrate. <Embodiment 9> A Co--Cr--Ta--Si magnetic film 33' was formed directly on a [100] MgO substrate by a method similar to that used in Embodiment 8 without forming any V film having the bcc crystallographic structure. A magnetic recording medium having the construction indicated in FIG. 9 was fabricated, in which a C protective film 34 was formed further thereon. Also in this magnetic recording medium the easy magnetization axis was aligned in <001> of the [100] MgO substrate in the same way as described previously. <Embodiment 10> A magnetic recording apparatus was fabricated, in which a rectangular magnetic recording medium 111 fabricated in Embodiment 8 or Embodiment 9 was combined with a multi-head 112, in which a number of magnetic heads were arranged on one straight line, as indicated in FIG. 20, and magnetic recording/reproduction characteristics thereof were measured. The multi-head 112 indicated in FIG. 20 effects high speed simple oscillation movement, keeping an spacing of about 0.05 μm from the magnetic recording medium 111 and the magnetic recording medium is so constructed that it can move over an arbitrary distance with a high speed in a direction perpendicular to this simple oscillation movement. The linear density characteristics of the magnetic recording medium measured by means of this instrument were D 50 =75 kFCI for the magnetic recording medium, in which the V film was disposed, and D 50 =68 kFCI for a magnetic recording medium, in which no V film was disposed. <Embodiment 11> A concentric grating having protruding portions 100 nm wide and recess portions 400 nm wide and 50 nm deep with a pitch of 500 nm was formed by the photolithographic method on a surface of a glass substrate having a diameter of 1.8 inches. A magnetic recording medium indicated in FIG. 21 was prepared by a process described below, using this substrate. An MgO film 122 100 nm thick having the NaCl structure was formed on the substrate 121 kept at a high temperature by the radio frequency sputtering method. After the formation of the film, it was subjected to heat treatment in an electric oven kept in an inert gas atmosphere. The MgO film was examined by the X-ray diffraction method. As the result, it was verified that the MgO film was an oriented polycrystalline film, whose {100} plane was approximately parallel to the substrate. It was confirmed further that the [001] orientation of crystal grains was distributed approximately concentrically. Micro structure of the MgO film was examined by means of a scanning electron microscope. and it was verified that it consisted of crystal grains having grain sizes of 100 to 300 nm After having polished the surface so as to be flat, a Cr film 123 50 nm thick having a bcc crystallographic structure and a Co--Cr--Pt film 124 15 nm thick having an hcp crystallographic structure were formed thereon by the radio frequency magnetron sputtering method. A Co-21 at % Cr-6 at % Pt target was used for forming the magnetic film. The temperature of the substrate was 400° C. at the formation of the Cr film and 180° C. at the formation of the Co--Cr--Pt magnetic film. The Ar gas pressure at sputtering was 10 mTorr and sputter power was 10 W/cm 2 . A recess pattern 125 for magnetic head following was formed on this magnetic recording medium by the photolithographic method. That is, recesses of 1.5 μm×1.5 μm×0.1 μm were formed by the pattern etching method using photoresist in a zigzag shape and then a carbon film 126 10 nm thick was formed as a protective film. By using the magnetic recording medium according to the present embodiment, since the magnetic recording/reproduction characteristics thereof are improved, it is possible to increase the areal recording density in principle. In addition, since it is possible to realize a high precision tracking by monitoring variations in reflectivity of a light beam emitted by a semiconductor laser device mounted on a part of the magnetic head due to a series of recesses formed on the medium or by utilizing a phenomenon, by which the output of the magnetic head varies when the magnetic head arrives directly above every recess, it is possible to increase significantly the recording density in the track direction and thus to select a combination of the linear density and the density in the track direction in a wide range. As the result, it is possible to effect more easily a high density magnetic recording. <Embodiment 12> A concentric grating 42 having a depth of 50 nm and a pitch of 100 nm was formed on a surface of a quartz glass substrate 41 having a diameter of 1.8 inches by means of a diamond tip having a tip angle of 90°. A magnetic recording medium as indicated in FIG. 10 was prepared by a process described below, using this substrate. An LiF film 43 100 nm thick having an NaCl structure was formed on the substrate 41 kept at a high temperature by the radio frequency sputtering method. After the formation of the film, it was subjected to heat treatment in an electric oven kept in an inert gas atmosphere containing water vapor. The LiF film was examined by the X-ray diffraction method. As the result, it was verified that the LiF film was an oriented polycrystalline film, whose {110} plane was approximately parallel to the substrate. It was confirmed further that [001] orientation of crystal grains were distributed approximately concentrically. Micro structure of the LiF film was examined by means of a scanning electron microscope and it was verified that it consisted of crystal grains having grain sizes of 50 to 100 nm and further that there existed unevenness of 30 to 100 nm on the surface. After having polished the surface so as to be flat, a Cr film 44 50 nm thick having a bcc crystallographic structure and a Co--Cr--Pt film 45 30 nm thick having an-hcp crystallographic structure were formed thereon by the radio frequency magnetron sputtering method. A Co-18 at % Cr-6 at % Pt target was used for forming the magnetic film. The temperature of the substrate was 400° C. at the formation of the Cr film and 180° C. at the formation of the Co--Cr--Pt magnetic film. The Ar gas pressure at sputtering was 3 to 10 mTorr and sputter power was 6 to 10 W/cm 2 . Further a carbon film 10 nm thick was formed as a protective film 46 to fabricate the magnetic recording medium. The structure of the film was examined by the X-ray diffraction and it was confirmed that the Cr film was a <211> oriented polycrystalline film, while the Co --Cr--Ta film was a <1100> oriented polycrystalline film. Magnetic recording media, in which V, Nb, Mo, Cr-5 at % Ti, Cr-2 at % Zr, Cr-20 at % V and Cr 1 at % B were used in lieu of Cr, were fabricated under the conditions identical to those described above. It was verified by the X-ray diffraction method that structures similar to those described previously were realized in both the underlayer having the bcc structure and the magnetic film having the hcp crystallographic structure. A magnetic recording medium was fabricated as a sample for comparison, in which the Cr film, the Co--Cr --Pt magnetic film and the C protective film were formed under the same conditions as described above directly on a quartz glass substrate on which no grating was formed. As a result of X-ray diffraction it was confirmed that the Cr film exhibited a configuration, in which two sorts of orientation, i.e. <100> and <110>, were mixed, that in the magnetic film there existed mixedly crystal grains, whose easy magnetization axis was parallel to the substrate, and crystal grains, whose easy magnetization axis was inclined by about 30° with respect to the substrate, and that directions of the easy magnetization axis were distributed irregularly in the plane of the substrate. Evaluation of recording/reproduction characteristics of these magnetic recording media was effected by means of a thin film magnetic head. The magnetic head had a track width of 5 μm and a gap length of 0.2 μm. The distance between the magnetic head and the magnetic recording medium at measurement was 0.06 μm and the relative speed therebetween was 10 m/s. Recording density characteristics, S/N ratio and off-track characteristics were chosen as evaluation items. The recording density characteristics were measured as a half output recording density (D 50 ), at which a low frequency reproduced output is decreased to a half; the S/N ratio was measured as a relative value on the basis of an S/N ratio obtained for the sample for comparison; and the off-track characteristics were measured as a relative value of the magnetization spread out beyond the recorded track edge, compared with that obtained for the sample for comparison. Increasing value of the S/N ratio and decreasing value of the off-track. characteristics indicate that they are more suitable for high-density magnetic recording. From TABLE 5 it was verified that the magnetic recording medium according to the present embodiment is improved in all the recording density characteristics, the S/N ratio and the off-track characteristics with respect to the example for comparison and that it has characteristics desirable for a high-density magnetic recording medium. TABLE 5__________________________________________________________________________ EXAMPLE FOR COM- PARISON EMBODIMENT 12__________________________________________________________________________NaCl STRUC- NONE <100> ORIENTED LiF FILMTURE FILMbcc STRUC- Cr Cr V Mb Mo Cr--Ti Cr--Zr Cr--V Cr--BTURE FILMRECORDING 65 87 85 76 73 95 90 91 90DENSITY(D.sub.50 (kFCI)S/N RATION 1 1.8 1.7 1.5 1.6 1.9 1.8 1.7 1.7(RELATIVEVALUE)OFF-TRACK 1 0.5 0.6 0.6 0.5 0.3 0.5 0.3 0.5CHARACTE-RISTICS(RELATIVEVALUE)__________________________________________________________________________ Experiments were effected also by using a <110> oriented film made of either one of LiCl, NaCl, KCl, MgO, CaO, TiO, VO, MnO, CoO, NiO, TiC, ZrC, HfC, NbC and TaC in lieu of LiF as a material having the NaCl type crystallographic structure. When a different material is used, the condition for the grapho-epitaxial growth varies. Thus it was necessary to select a film forming method suitable for a certain material or conditions such as substrate temperature at the film formation, heat treatment after the film formation, etc. However it was confirmed that in all the cases where these <110> oriented textured films are used, they have characteristics desirable for a high-density magnetic recording medium, which are similar to those described previously. <Embodiment 13> A <110> oriented film 43 having the NaCl structure, an oriented magnetic film 45' having the hcp structure and a protective film 46 were formed one after another on a surface of a quartz glass substrate 41 having a diameter of 1.8 inches, in which a concentric grating having a depth of 50 nm and a pitch of 100 nm was formed by a process similar to that described previously in Embodiment 12, except that the film formation using the material having the bcc crystallographic structure was omitted, to fabricate a magnetic recording medium having the structure indicated in FIG. 11. For the magnetic film a binary alloy selected from the group consisting of Co-18 at % Cr, Co-12 at Ni, Co-18 at % Fe, Co-20 at % V, Co-20 at % Mo, Co-16 at % Ta, Co-20 at % Re, Co-16 at % Pt and Co-15 at % Pd; a ternary alloy selected from the group consisting of Co-18 at % Cr-2 at % Ta, Co-21 at % Cr-3 at % Mo, Co-19 at % Cr-1.5 at % W, Co-15 at % Cr-7 at % Re, Co-14 at % Ni-1 at % Zr, Co-16 at % Pt-2 at % Ta, and Co-18 at % Pt-0.8 at % B; or a quarternary alloy selected from the group consisting of Co-18 at % Cr-2 at % Ta-2 at % B, Co-20 at % Cr-1.5 at % Ta-0.3 at % Si, Co-19 at % Cr-2.5 at % Ta-0.8 at % C, Co-22 at % Cr-1.6 at Ta-0.2 at % P, Co-21 at % Cr-1 at % Ta-0.2 at N, Co-12 at % Cr-8 at % Pt-0.7 at % B, was used. Magnetic recording media were prepared for samples for comparison, in each of which a Cr film 50 nm thick serving as an underlayer was formed on a flat quartz glass substrate, then one of the magnetic films described above was formed thereon, and finally a C protective film was formed further thereon. Linear densities (D 50 : kFCI) among recording/reproduction characteristics of magnetic recording media obtained by using <110> oriented films of NiO as the material having the NaCl crystallographic structure were as indicated in TABLE 6. TABLE 6__________________________________________________________________________MAGNETIC EXAMPLE FORFILM COMPARISON EMBODIMENT 6__________________________________________________________________________ NaCl NONE <100> ORIENTED STRUCTURE NiO FILM FILM bcc Cr NONE STRUCTURE FILMCo--Cr 62 81Co--Ni 58 78Co--Fe 56 75Co--V 60 80Co--Mo 58 74Co--Ta 50 80Co--Re 48 72Co--PT 56 74Co--Pd 55 81Co--Cr--Ta 65 85Co--Cr--Pt 64 90Co--Cr--Mo 61 85Co--Cr--W 58 78Co--Cr--Re 62 86Co--Ni--Zr 62 86Co--Pt--Ta 63 90Co--Pt--B 66 93Co--Cr--Ta--B 66 94Co--Cr--Ta--Si 65 90Co--Cr--Ta--C 64 86Co--Cr--Ta--P 60 80Co--Cr--Ta--N 62 83Co--Cr--Pt--B 63 90__________________________________________________________________________ For the S/N ratio and the off-track characteristics other than the linear density, it was verified that characteristics of the magnetic recording media according to the present embodiment were improved by more than 10% with respect to samples for comparison having magnetic films of same compositions formed by using prior art Cr underlayers and that they were therefore excellent as high density magnetic recording media. Also in case where the magnetic films were formed on <110> oriented films having the NaCl crystallographic structure other than NiO, similar improvement effects were recognized. <Embodiment 14> Grooves 52 having a depth of 20 nm and a pitch of 75 nm was formed concentrically in a surface portion of a quartz glass substrate 51 having a diameter of 1.8 inches by means of a diamond tip having a tip angle of 90°. A magnetic recording medium as indicated in FIG. 12 was prepared by a process described below, using this substrate. A KCl film 53 50 nm thick having an NaCl structure was formed on the substrate 51 by the radio frequency sputtering method. After the formation of the film, it was subjected to heat treatment in an electric oven kept in a gas atmosphere containing water vapor. The KCl film was examined by the X-ray diffraction method. As the result, it was verified that the KCl film was an oriented polycrystalline film, in which two sorts of planes, {110} and {100}, were approximately parallel to the substrate. By the X-ray diffraction it was verified that a diffraction beam intensity coming from the {110} plane is intense and that the oriented textured plane is {110}. It was confirmed further that crystal grains were distributed approximately concentrically. Micro structure of the KCl film was examined by means of a scanning electron microscope and it was verified that it consisted of crystal grains having grain sizes of 30 to 100 nm and further that there existed unevenness of 20 to 50 nm on the surface. After having polished the surface so as to be flat, a Cr-2 at % Zr film 54 50 nm thick having a bcc crystallographic structure and a Co--Cr--Ta film 55 20 nm thick having an hcp crystallographic structure were formed thereon by the radio frequency magnetron sputtering method. A Co-18 at % Cr-3 at % Ta target was used for forming the magnetic film. The temperature of the substrate was 300° C. at the formation of the Cr--Zr film and 150° C. at the formation of the Co--Cr--Ta magnetic film. The Ar gas pressure at sputtering was 3 to 10 mTorr and sputter power was 6 to 10 W/cm 2 . Further a carbon film 10 nm thick was formed as a protective film 56 to fabricate the magnetic recording medium. The structure of the film was examined by the X-ray diffraction and it was confirmed that although 200 diffraction was slightly observed for the Cr--Zr film, a diffraction beam intensity due to 211 diffraction was intense and therefore the Cr--Zr film was a <211> oriented textured film, while the Co--Cr--Ta film was a <1100> oriented textured polycrystalline film. <Embodiment 15> A Co--Cr--Ta magnetic film 55' was formed directly on a KCl film 53 deposited on a glass substrate 51, on which grooves 52 were formed, by a method similar to that used in Embodiment 14 without forming any Cr--Zr film having the bcc crystallographic structure. A magnetic recording medium having the construction indicated in FIG. 13 was fabricated, in which a C protective film 34 was formed further thereon. A magnetic recording medium was fabricated as a sample for comparison for Embodiment 14 and Embodiment 15, in which the Cr--Zr film, the Co--Cr--Ta film and the C protective film were formed directly on a flat quartz glass substrate. Recording/reproduction characteristics were compared under conditions similar to those used in Embodiment 12. As a result it was confirmed that all the magnetic recording media according to Embodiment 14 and Embodiment 15, in which the KCl film exhibiting the <110> dominant orientation was disposed, were better by 20% in the linear density, by 45% in the S/N ratio and by more than 30% in the off-track characteristics than the sample for comparison. Further, also in case where LiCl, NaCl or LiF was used as another material instead of the KCl film, similar desirable effects were confirmed. <Embodiment 16> A magnetic recording medium having a construction indicated in FIG. 14 was fabricated by a process described below, using a rectangular [110] MgO single-crystal substrate, whose one side was 20 mm long, as a substrate 61. A V film 62 30 nm thick having a bcc crystallographic structure and Co--Cr--Ta--Si film 63 15 nm thick having an hcp crystallographic structure were formed thereon by the radio frequency magnetron sputtering method. A Co-19 at % Cr-2 at % Ta-2 at % Si target was used for forming the magnetic film. The temperature of the substrate was 450° C. at the formation of the V film and 150° C. at the formation of the Co--Cr --Ta--Si magnetic film. The Ar gas pressure at sputtering was 3 mTorr and sputter power was 10 W/cm 2 . Further a boron film 10 nm thick was formed as a protective film 64 to fabricate the magnetic recording medium. The structure of the film was examined by the X-ray diffraction and it was confirmed that the V film grew epitaxially so that the {211} plane was parallel to the substrate and that the Co--Cr--Ta--Si film grew epitaxially so that the {1100} plane was parallel to the substrate. The structure of the magnetic recording medium was examined by means of a transmission electron microscope and it was found that sub-grain boundary existed in the magnetic film and that crystal grains divided by this sub-grain boundary had inclinations comprised between 0.3° to 1°. The average size of the crystal grains was 45 nm. Further the composition of the interior of the crystal grains was also examined and it was found that Cr and Si were segregated in the neighborhood of the sub-grain boundary. Easy magnetization axes of this magnetic recording medium were aligned in one direction, which corresponded to [001] of the [110] MgO substrate. <Embodiment 17> A Co--Cr--Ta--Si magnetic film 63' was formed directly on a [110] MgO substrate 61 by a method similar to that used in Embodiment 16 without forming any V film having the bcc crystallographic structure. A magnetic recording medium having the construction indicated in FIG. 15 was fabricated, in which a C protective film 64 was formed further thereon. Also in this magnetic recording medium the easy magnetization axes were aligned in one direction. <Embodiment 18> A magnetic recording apparatus was fabricated, in which a rectangular magnetic recording medium 131 fabricated in Embodiment 16 or Embodiment 17 was combined with a multi-head 132, in which a number of magnetic heads were arranged on one straight line, as indicated in FIG. 22, and magnetic recording/reproduction characteristics thereof were measured. The multi-head 132 indicated in FIG. 22 effects a high speed simple oscillation movement, keeping a distance of about 0.05 μm from the magnetic recording medium 131 and the magnetic recording medium is so constructed that it can move over an arbitrary distance with a high speed in a direction perpendicular to the simple oscillation movement. Linear density characteristics of the magnetic recording medium measured by this method was D 50 =72 kFCI for a magnetic recording medium, in which a V film was disposed, and D 50 =65 kFCI for a magnetic recording medium, in which no V film was disposed. <Embodiment 19> A grating having a depth of 50 nm and a pitch of 100 nm was formed concentrically in a surface portion of a quartz glass substrate 141 having a diameter of 1.8 inches by means of a diamond tip having a tip angle of 90°. A magnetic recording medium having a construction indicated in FIG. 23 was prepared by a process described below, using this substrate. An MgO film 142 100 nm thick having an NaCl structure was formed on the substrate 141 kept at a high temperature by the radio frequency sputtering method. After the formation of the film, it was subjected to heat treatment in an electric oven kept in an inert gas atmosphere. The MgO film was examined by the X-ray diffraction method. As the result, it was verified that the MgO film was an oriented polycrystalline film, in which {110} planes were approximately parallel to the substrate, and further that the [001] direction of crystal grains are distributed approximately concentrically. Micro structure of the MgO film was examined by means of a scanning electron microscope and it was verified that it consisted of crystal grains having grain sizes of 20 to 50 nm. After having polished the surface so as to be flat, a Cr film 143 50 nm thick having a bcc crystallographic structure and a Co--Cr--Pt film 144 15 nm thick having an hcp crystallographic structure were formed thereon by the radio frequency magnetron sputtering method. A Co-21 at % Cr-6 at % Pt target was used for forming the magnetic film. The temperature of the substrate was 400° C. at the formation of the Cr film and 180° C. at the formation of the Co--Cr--Pt magnetic film. The Ar gas pressure at sputtering was 10 mTorr and sputter power was 10 W/cm 2 . A recess pattern 145 for magnetic head following was formed on this magnetic recording medium by the photolithographic method. That is, recesses of 1.5 μm×1.5 μm×0.1 μm were formed by the pattern etching method using photoresist in a zigzag shape. Then a carbon film 10 nm thick was formed as a protective film 146. By using the magnetic recording medium according to the present embodiment, since the magnetic recording/reproduction characteristics thereof are improved, it is possible to increase the areal recording density in principle. In addition, since it is possible to realize a high precision tracking by monitoring variations in reflectivity of a light beam emitted by a semiconductor laser device mounted on a part of the magnetic head due to a series of recesses formed on the medium or by utilizing a phenomenon, by which the output of the magnetic head varies when the magnetic head arrives directly above every recess, it is possible to increase significantly the recording density in the track direction and thus to select a combination of the linear density and the density in the track direction in a wide range. As the result, it is possible to effect more easily a high density magnetic recording.

A magnetic recording medium is constructed with a substrate made of glass, one or two underlayers, and a magnetic film. In order that the easy magnetization axis of the magnetic film is parallel to the magnetic film, an underlayer having an NaCl crystallographic structure is superposed on the substrate. A magnetic film made of a Co based alloy having a hexagonal close packed crystallographic structure is formed on this underlayer, putting an underlayer made of a material having a body centered cubic crystallographic structure therebetween at need. Magnetic anisotropy of the magnetic film is increased by forming grooves in a predetermined direction in a surface portion of the substrate. These grooves play a role also for defining the orientation of the underlayer made of the material having an NaCl crystallographic structure.

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The invention relates to a method for fabricating liquid crystal display (LCD) devices, and in particular to a method for fabricating a plastic substrate structure for LCD devices. [0003] 2. Description of the Related Art [0004] Liquid crystal displays typically exhibit excellent characteristics such as low power consumption, light weight, and good outdoor reliability, and are therefore widely applied in portable computer, notebook, mobile phone, and personal digital assistants (PDA). Philips Inc. in Society for Information Display (SID) discloses that flexibility is improved when total thickness of the liquid crystal display is reduced. Generally, when total thickness of the display is less than 400 μm, the display becomes flexible to bendable. [0005] Color filters are key parts of full color display devices. Conventional color filters are formed on thick, heavy, and brittle glass substrate, limiting application in display devices. Conversely, some attempts have been made to introduce transparent plastic substrates to small single color gray scale display devices. As requirements for full color display devices increase, however, thinner, lighter, and flexible transparent plastic substrates are required for liquid crystal display applications. [0006] Plastic substrates, however, are not only limited to processing temperatures, but their dimensions are also affected by thermal processes, resulting in asymmetrical expansion and shrinkage. FIG. 1 is a schematic view illustrating asymmetrical expansion and shrinkage of a plastic substrate after thermal processes. More specifically, the axis along the conveyance of the plastic substrate 100 is defined as working axis d x , and the axis vertical to the working axis d x is defined as extension axis d y . The working axis d x and extension axis d y exhibit inconsistent expansion and shrinkage behavior after each thermal process, affecting precision of subsequent formation of color filters. Furthermore, plastic substrates tendency for humidity absorption can cause expansion related dislocation of color filters. Controlling expansion and shrinkage is thus important for plastic substrate LCD devices. [0007] U.S. Pat. No. 6,737,338, the entirety of which is hereby incorporated by reference, discloses a method for forming high precision color filter patterns. By sputtering inorganic passivation layers on both sides of the plastic substrate, expansion of the plastic substrate is prevented. Application and exposure of the photoresist are also carefully controlled to achieve color filters with high accuracy of superpositioning on the plastic substrate. [0008] Samsung Electronics in Society for Information Display (SID) 2004 discloses a method for forming PES substrates for LCD devices. An 180° C.-48 hr annealing process is performed on the PES substrate, and an organic passivation layer is sequentially deposited on thereon before thin film transistor (TFT) devices or color filters are formed. The precision of the TFT devices can reach 100 ppi. Conventional methods, however, require formation of inorganic passivation layers on the plastic substrates, higher and longer thermal process cycles, complicating production and decreasing yield. BRIEF SUMMARY OF THE INVENTION [0009] A detailed description is given in the following embodiments with reference to the accompanying drawings. [0010] A method for fabricating a transparent plastic substrate structure for a liquid crystal display device is provided. A plastic substrate is heated and maintained at near glass transition temperature, and then quenched to room temperature to prevent asymmetrical expansion and shrinkage of plastic substrate, thereby providing color filters with high accuracy of dimension, position, and superposition. [0011] According to an embodiment of the invention, a method of fabricating a plastic substrate for a liquid crystal display device comprises providing a plastic substrate, heating the plastic substrate to a first temperature and maintaining the first temperature, and quenching the plastic substrate to a second temperature, retaining the microstructure of the plastic substrate under the first temperature. [0012] According to another embodiment of the invention, a method of fabricating a plastic substrate for a liquid crystal display device comprises providing a plastic substrate, heating the plastic substrate to at least 5° below the glass transition temperature (T g ), maintaining the plastic substrate temperature for a first period; quenching the plastic substrate to a second temperature, and forming a color filter on the plastic substrate. BRIEF DESCRIPTION OF THE DRAWINGS [0013] The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: [0014] FIG. 1 is a schematic view illustrating asymmetrical expansion and shrinkage of a plastic substrate after thermal processes; [0015] FIG. 2 is a temperature profile of thermal treatment on a plastic substrate before color filters are formed thereon according to an embodiment of the invention; [0016] FIG. 3 is a temperature profile of thermal treatment on a plastic substrate before color filters are formed thereon according to another embodiment of the invention; and [0017] FIG. 4 shows color filters on a plastic substrate according to an embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION [0018] The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims. [0019] The invention is directed to thermal treatment on a plastic substrate to prevent asymmetrical expansion and shrinkage during subsequent thermal processes, thereby providing color filters with high accuracy of dimension, position, and superposition. [0020] According to an aspect of the invention, a thermal treatment is performed on the plastic substrate before color filter fabrication such that the plastic substrate retains microstructures from the high temperature state. The plastic substrate, after thermal treatment, exhibits reversible thermal expansion and shrinkage, simplifying color photoresist lithography. [0021] In an exemplary embodiment, a plastic substrate, preferably a polyethersulphone (PES) substrate, is provided for receiving color filters thereon. FIG. 2 is a temperature profile of thermal treatment on a plastic substrate before color filters are formed thereon according to an embodiment of the invention. The plastic substrate is heated to 180° C. for 1 hour, and then quenched to a room temperature. Cooling rate for the plastic substrate exceeds 5° C./min, thereby retaining microstructures from high temperature state. The microstructure of the plastic substrate after thermal treatment shows less than 50% crystallization. Red (R), green (G), and blue (B) color filters are sequentially formed on the substrate by spin coating. Each color filter fabrication comprises spin coating, soft bake, exposure, developing, and hard bake. Each color filter is hard baked at 180° C. for 1 hr. [0022] Note that the plastic substrate comprises a polyethersulphone (PES) substrate, a polycarbonate (PC) substrate, a polyethylenetelephthalate (PET) substrate, or a polyethylenenaphthalate (PEN) substrate. The plastic substrate has a glass transition temperature (T g ), and is preferably heated at least 5° below the glass transition temperature (T g ). Alternatively, the plastic substrate has a melting temperature (T m ), and the plastic substrate is preferably heated at least 5° below the melting temperature (T m ). [0023] FIG. 3 is a temperature profile of thermal treatment on a plastic substrate before color filters are formed thereon according to another embodiment of the invention. The plastic substrate is heated to 150° C. for 1 hour, and then quenched to room temperature. Red (R), green (G), and blue (B) color filters are sequentially formed on the substrate by spin coating. Each color filter fabrication comprises spin coating, soft bake, exposure, developing, and hard bake. Each color filter is hard baked at 150° C. for 1 hr. [0024] Color filters on a plastic substrate are shown in FIG. 4 . Each color filter of red (R), green (G) and blue (B) has a pixel width of approximately 260 μm. Superposition between pixel regions is approximately less than 5 μm. Compared to conventional color filters on glass substrate, the color filters on a plastic substrate are competent. [0025] The invention is advantageous in that a thermal treatment is performed on a plastic substrate before color filters are formed. The plastic substrate is quenched from a high temperature to room temperature, retaining microstructures from the high temperature state. The color filters on the plastic substrate comprise high accuracy of dimension, position, and superposition after thermal treatment. [0026] While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.

A method of fabricating plastic substrates for a liquid crystal display device. A plastic substrate is provided. The plastic substrate is heated to a first temperature and maintain at the first temperature. Next, the plastic substrate is quenched to a second temperature, retaining microstructure of the plastic substrate from the first temperature.

FIELD OF THE INVENTION The present invention relates to an improvement in the mounting of a power take off device to a transmission. More particularly, the present invention relates to a means for facilitating the securing of a power take off device to a transmission and method associated therewith. BACKGROUND OF THE INVENTION A power take off (P.T.O.) device is a mechanical device used to operate various components, such as hydraulic pumps or mechanical devices, by taking advantage of the power of a transmission. To receive input from a transmission, a P.T.O. device is mounted such that one of the P.T.O. gears engages a transmission gear. The P.T.O. is mounted to the transmission at an opening generally provided by the transmission manufacturer. An example of a standard opening provided by transmission manufacturers is the SAE 6 BOLT P.T.O opening. Over the years, while the transmission opening has remained the same, the P.T.O. housings that mount to the openings have grown to accommodate larger gears. In order to pull the most horsepower possible from the transmission openings, the size of the P.T.O. gears must be maximized, resulting in larger P.T.O. gears and thus, larger P.T.O housings. To mount a standard 6 BOLT P.T.O. device to a transmission having a 6 BOLT opening, six threaded studs with a respective securing nut or six capscrews have been used. The space allotted for the studs with nuts or capscrews has become minimal due to the clearance problems associated with the use of larger P.T.O housings. To install and retain the P.T.O. device to the transmission by way of a standard stud with a nut, a box wrench is most conveniently used to tighten the nut. Frequently, the wrench must be ground or cut down to be able to fit over the head of the nut in order to tighten the nuts, due to clearance problems with the P.T.O. housing. Even modified wrenches do not always allow sufficient room to tighten the nut properly. Thus, there is a need in the art for a method and device which facilitates the attachment of a standard P.T.O. device to a standard P.T.O. opening on a transmission. It is a purpose of this invention to fulfill this and other needs in the art which will become more apparent to the skilled artisan once given the following disclosure. SUMMARY OF THE INVENTION Generally speaking, this invention fulfills the above-described needs in the art, by providing a securement assembly for securing a power take off device to a transmission. The power take off device includes a plurality of apertures for receiving a plurality of securement means. The transmission includes a plurality of apertures which may be aligned with each aperture of said power take off device and secured by the securement means and wherein there is a limited space between the plurality of apertures of the power take off device and the housing of the power take off device. The securement means includes a plurality of studs each having a head and tail portion. Each head portion includes a non-threaded portion disposed at an interface of the head and tail portion. Each head portion is adapted for being screwed into a respective, aligned aperture of the transmission. Each non-threaded portion of the head portions is adapted to receive a plurality of apertures of the power take off device such that the power take off device is supported and aligned for securement thereby. Each tail portion protrudes from a respective aperture of the power take off device and is adapted to receive a smaller nut for rigidly securing the power take off device to the transmission. This invention fulfills further needs in the art by providing a method for securing a power take off device to a transmission by a plurality of stepstuds. The transmission includes a housing and an opening for operatively receiving a power take off device. The power take off device includes a plurality of apertures for receiving a plurality of securement means. The transmission housing includes a plurality of apertures which may be aligned with the apertures of the power take off device and secured by the securement means. The securement means include a plurality of stepstuds each having a head and tail portion. The head portion includes a non-threaded portion which is disposed at an interface of the head and tail portion. Each head portion is screwed into a respective aperture of the transmission housing such that each non-threaded portion of the head portions protrude from the transmission. The plurality of apertures of the power take off device are aligned onto a respective protruding non-threaded head portion such that the power take off device is supported on the non-threaded head portions and said tail portion protrudes from a respective aperture of the power take off device and from which a plurality of nuts may be secured so that said power take off device is rigidly secured to the transmission housing. The respective nuts are screwed onto respective tail portions of the stepstuds. The invention will now be described with respect to certain embodiments thereof as illustrated in the following drawings, wherein: BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of the stepstud of the present invention; FIG. 2 is an exploded view of a transmission and a P.T.O. device to be secured according to the present invention; FIG. 3 is a side elevational view of the power take off device taken along lines 3--3 of FIG. 2; FIG. 4 is a fragmentary top plan view of the power take off device as seen from lines 4--4 of FIG. 3; FIG. 5 is a side view of the stepstud as it is installed according to the present invention; and FIG. 6 is a side view of the stepstud as it is used according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Attention is directed to FIG. 1 of the drawings. In this figure, there is illustrated one embodiment of a stepstud S which may be used in the practice of this invention. Stepstud S is designed to improve the ease by which a power take off device may be mounted and secured to a transmission. Stepstud S includes a head portion 10 and a tail portion 14, the diameter of head portion 10 of which is larger than the diameter of tail portion 14. Head portion 10 of stepstud S includes a threaded portion 16 and a non-threaded portion 18. Similarly, tail portion 14 of stepstud S includes a non-threaded portion 20 and a threaded portion 22. Stepstud S is configured so that threaded portions 16 and 22 are located at its ends, while the non-threaded portions 18 and 20 are located at interface 24 of head portion 10 and tail portion 14. Given this configuration stepstud S may now be used to mount a power take off device to a transmission and at the same time overcome the above-described problem in the prior art. With reference in particular to FIG. 2, there is illustrated a power take off device P to be mounted to a transmission T. Transmission T is provided with a transmission housing 40 which houses a plurality of drive gears (not shown), and an opening 44 which allows access to the gears. Transmission T also includes a mounting flange 46 with a plurality of threaded apertures 48 disposed along its perimeter. In the preferred embodiment, transmission opening 40 is a standardized S.A.E. 6 BOLT opening with a hexagonal pattern. It should be understood that the present invention is not limited to the six-hole standardized pattern disclosed herein, but may be used with an eight hole octagonal pattern, or any other power take off device and transmission having complimentary bolt hole patterns. Similarly, power take off device P includes gears 52 which engage complimentary transmission gears (not shown), housing 54 which houses gears 52, and a mounting flange 56. Like transmission housing 40, P.T.O. mounting flange 56 conventionally includes a plurality of apertures 60 disposed along its perimeter which are designed to align with apertures 48 of transmission mounting flange 46. Each pair of aligned apertures may be secured by a stud with a nut. Because of the size of the P.T.O. housing 54 (as shown in FIG. 2), the standard threaded stud with a nut gives rise to the above-described problem when securing the P.T.O. unit P to transmission T. With particular reference to FIGS. 3 and 4, the space surrounding apertures 60 along the P.T.O. mounting flange 56 from which a nut is secured, is limited due to the size and configuration of the P.T.O. housing. Typically, as is shown in the FIG. 3 and 4, grooves 62 are designed into the housing proximate each aperture 60 to facilitate use of a tool to secure each nut. However, even this space has become minimal due to the increase in size of the P.T.O. housings. Thus, it becomes difficult to secure a nut to the protruding tail portion of a stud. The use of the Stepstud S of the present invention to secure P.T.O. device P to transmission T, on the other hand, substantially eliminates this problem by providing a smaller tail portion 14 from which a smaller nut may be more easily used for securement. The use of a smaller nut allows for a smaller wrench or the like to be used which can then grasp and manipulate the associated nuts, without potential interference by or contact with the P.T.O. housing, and without having to either design a special wrench, or cut a standard wrench to size. With reference to FIG. 5, the securement of P.T.O. device P to transmission T by a plurality of stepstuds S will now be described. In the preferred embodiment, P.T.O. mounting flange 56 and transmission housing 40 each have six apertures having equal diameters. Each aperture 48 of transmission housing 40 is threaded on the inside to receive a standard stud. A typical, standard 6 BOLT P.T.O. opening on a transmission includes threaded apertures 48 with a 3/8" diameter. Thus, the head portion 10 of stepstud S is sized to screw inside the apertures 48 of transmission housing 40 (e.g. a matching 3/8" diameter). Before the P.T.O. device P is aligned with transmission T for securement, a head portion 10 of a stepstud S is screwed into an aperture 48 of transmission housing 40. To facilitate this securement, two flat washers 70 and nut 72 are used. Flat washers 70 are placed through tail portion 14 until they abut interface 24 of head portion 10 and tail portion 14. In the preferred embodiment, two 5/16" flat washers are used and are received on tail portion 14 which is also 5/16". Nut 72 is screwed onto the threads of tail portion 14 until nut 72 abuts flat washers 70. Once nut 72 abuts flat washers 70, stepstud S is installed into the transmission by twisting of nut 72 by a wrench or the like. Threaded portion 16 of head portion 10 screws into threaded apertures 48 of transmission housing 40 until the threads bottom out, leaving non threaded portion 18 protruding from transmission housing 40. The above identified described installment of stepstud S into an aperture 48 of transmission housing 40 is repeated for all apertures 48 of transmission housing 40. Once stepstuds S are installed into all apertures 48 of transmission housing 40, the P.T.O. device P may be aligned for securement. The protruding non-threaded portions 18 provide a surface from which apertures 60 of P.T.O. device P may be mounted. The diameter of apertures 60 of P.T.O. device P should be about the same as the diameter of the non-threaded portions 18, thus sufficiently providing the proper alignment, and stability for mounting the P.T.O. device P. With reference now to FIG. 6, the P.T.O. mounting flange 56 is placed on non-threaded portion 18 such that flange 56 abuts transmission housing 40. In addition, a sealant 80 may be placed between P.T.O. mounting flange 56 and transmission housing 40, and can be a gasket or any suitable sealant material which will prevent fluid leakage. Once the P.T.O. mounting flange 56 is aligned and supported on non-threaded portion 18 of head portion 10, each threaded tail portion 14 of a respective stepstud S may be secured by a flange nut 84. In a preferred embodiment, threaded tail portions 14 have a 5/16" diameter and are secured by standard 5/16" flange nuts. Thus, a smaller wrench or the like can be used to tighten the nuts to retain the P.T.O. device P to transmission T. For example, in one preferred embodiment, a conventual 1/2" end or box wrench may be used to tighten the nuts. In this way the clearance problem is avoided, while only a conventional wrench is needed to insure proper securement between a P.T.O. device P and a transmission T without thread damage to the exposed P.T.O. stud threads, such as might occur if a stud tool were employed. An adhesive 30 may optionally be applied to the threads of the head portion 10 to improve the securement of stepstud S to the transmission. The adhesive may be Loctite Dri-lock #202 threadlocker or 3M Scotchgrip #2353 fastener adhesive. Once given the above disclosure, many other features, modifications, and improvements will become apparent to the skilled artisan. Such features, modifications, and improvements are therefore to be considered a part of this invention, the scope of which is to be determined by the following claims:

A system for providing sufficient space to accommodate a wrench for tightening the securing nuts in the restricted confines of a power take off mounted to a vehicle's transmission which employs step studs whose large diameter ends are threaded into the standard S.A.E. hole pattern apertures of the transmission P.T.O. window, while the studs are designed to have significantly smaller opposite ends which protrude through the aligned P.T.O. housing apertures, thus allowing smaller nuts to be used to make room for the wrench.

CROSS REFERENCE TO RELATED APPLICATIONS [0001] The present application is a U.S. National Phase application pursuant to 35 U.S.C. §371 of International Application No. PCT/EP2012/058267 filed May 4, 2012, which claims priority to European Patent Application No. 11165130.3 filed May 6, 2011. The entire disclosure contents of these applications are herewith incorporated by reference into the present application. FIELD OF INVENTION [0002] The present patent application relates to medical devices of delivering at least two drug agents from separate reservoirs. Such drug agents may comprise a first and a second medicament. The medical device includes a dose setting mechanism for delivering the drug automatically or manually by the user. BACKGROUND [0003] The drug agents may be contained in two or more multiple dose reservoirs, containers or packages, each containing independent (single drug compound) or pre-mixed (co-formulated multiple drug compounds) drug agents. [0004] Certain disease states require treatment using one or more different medicaments. Some drug compounds need to be delivered in a specific relationship with each other in order to deliver the optimum therapeutic dose. The present patent application is of particular benefit where combination therapy is desirable, but not possible in a single formulation for reasons such as, but not limited to, stability, compromised therapeutic performance and toxicology. [0005] For example, in some cases it might be beneficial to treat a diabetic with a long acting insulin (also may be referred to as the first or primary medicament) along with a glucagon-like peptide-1 such as GLP-1 or GLP-1 analog (also may be referred to as the second drug or secondary medicament). SUMMARY [0006] Accordingly, there exists a need to provide devices for the delivery of two or more medicaments in a single injection or delivery step that is simple for the user to perform without complicated physical manipulations of the drug delivery device. The proposed drug delivery device provides separate storage containers or cartridge retainers for two or more active drug agents. These active drug agents are then only combined and/or delivered to the patient during a single delivery procedure. These active agents may be administered together in a combined dose or alternatively, these active agents may be combined in a sequential manner, one after the other. [0007] The drug delivery device also allows for the opportunity of varying the quantity of the medicaments. For example, one fluid quantity can be varied by changing the properties of the injection device (e.g., setting a user variable dose or changing the device's “fixed” dose). The second medicament quantity can be changed by manufacturing a variety of secondary drug containing packages with each variant containing a different volume and/or concentration of the second active agent. [0008] The drug delivery device may have a single dispense interface. This interface may be configured for fluid communication with the primary reservoir and with a secondary reservoir of medicament containing at least one drug agent. The drug dispense interface can be a type of outlet that allows the two or more medicaments to exit the system and be delivered to the patient. [0009] The combination of compounds as discrete units or as a mixed unit can be delivered to the body via a double-ended needle assembly. This would provide a combination drug injection system that, from a user's perspective, would be achieved in a manner that closely matches the currently available injection devices that use standard needle assemblies. One possible delivery procedure may involve the following steps: [0010] 1. Attach/mount a dispense interface to a distal end of the electro-mechanical injection device. The dispense interface comprises a first and a second proximal needle. The first and second needles pierce a first reservoir containing a primary compound and a second reservoir containing a secondary compound, respectively. [0011] 2. Attach/mount a dose dispenser, such as a double-ended needle assembly, to a connecting part at the distal end of the dispense interface. In this manner, a proximal end of the needle assembly is in fluidic communication with both the primary compound and secondary compound. For instance, a needle hub of the needle assembly is screwed on the connecting part of the dispense interface and thereby one end of a needle of the double-ended assembly intrudes into an outlet of the connecting part of the dispense interface, pierces a septum of the dispense interface arranged at the outlet and resides in fluid communication with a holding chamber of the dispense interface. The holding chamber may be in fluid communication with the first and second proximal needle. [0012] 3. Dial up/set a desired dose of the primary compound from the injection device, for example, via a graphical user interface (GUI). [0013] 4. After the user sets the dose of the primary compound, the micro-processor controlled control unit may determine or compute a dose of the secondary compound and preferably may determine or compute this second dose based on a previously stored therapeutic dose profile. It is this computed combination of medicaments that will then be injected by the user. The therapeutic dose profile may be user selectable. [0014] 5. Optionally, after the second dose has been computed, the device may be placed in an armed condition. In such an optional armed condition, this may be achieved by pressing and/or holding an “OK” button on a control panel. This condition may provide for greater than a predefined period of time before the device can be used to dispense the combined dose. [0015] 6. Then, the user will insert or apply the distal end of the dose dispenser (e.g., a double ended needle assembly) into the desired injection site. The dose of the combination of the primary compound and the secondary compound (and potentially a third medicament) is administered by activating an injection user interface (e.g., an injection button). [0016] Both medicaments may be delivered via one injection needle or dose dispenser and in one injection step. This offers a convenient benefit to the user in terms of reduced user steps compared to administering two separate injections. [0017] After a specific number of injections (e.g. 1 injection, 3 injections, 5 injections, 10 injections, 20 injections, 50 injections or the like) there is a risk for the dose dispenser and/or the dispense interface to be contaminated and, additionally, the tips of the needles of the dose dispenser and/or the dispense interface may be blunted. For instance, a blunted tip of a needle may not be able to sufficiently pierce a septum and/or tissue, for instance inserting a blunted needle in a desired injection site may be very painful. Furthermore, mechanical parts of the dose dispenser and/or the dispense interface such as a valve arrangement may only proper function for a specific number of injections (e.g. 1 injection, 3 injections, 5 injections, 10 injections, 20 injections, 50 injections or the like). [0018] Therefore, the dose dispenser and the dispense interface are disposable parts. For instance, the dose dispenser should only be used for one injection and the dispense interface should only be used with one first and second reservoir. However, attaching the dose dispenser to the connecting part of the dispense interface may be fiddly, for instance the diameter of the outlet may be about the diameter of the needle. Furthermore, the double-ended needle can jam (e.g. tilt) and, for instance, collide with side-walls of the holding chamber and damage the dispense interface. For instance, the needle assembly and, in particular, the double-ended needle may initially tilt when screwing the needle assembly on a connecting part of the dispense interface (e.g. because of the helix angle of the thread). [0019] To facilitate attaching the dose dispenser to the connecting part of the dispense interface and to prevent a collision of the double-ended needle with side-walls of the holding chamber a cross-sectional inner diameter of the outlet and the holding-chamber and/or a length of the holding chamber and/or a length of the double-ended needle may be increased and, correspondingly, the volume of the holding chamber and/or the liquid path is also increased. [0020] However, it is desired to minimize the liquid dead volume and the liquid path in front of the first and second reservoir, for instance the volume of the fluid communication paths in the dispense interface. For instance, there is a higher risk that a medicament contained in this liquid dead volume may be contaminated and/or cause any other undesired side-effects These side-effects may be for instance due to a lowered stability, compromised therapeutic performance and toxicology of a combination of the first and second medicament. [0021] Therefore, the present invention inter-alia faces the technical problem of facilitating attaching a dose dispenser to a connecting part such as a connecting part of a dispense interface and/or a medical device such as a drug delivery device and/or to minimize the liquid dead volume thereof. However, the present invention is not limited to a connecting part of a dispense interface and/or a medical device as described above and may basically relate to a connecting part of any dispenser such as a dispenser configured to eject adhesives such as multi-component adhesives (e.g. two-component adhesives) or the like. [0022] According to the present invention, an apparatus comprises a needle guide configured to at last partially receive a needle of a needle assembly in a longitudinal opening and to center the needle of the needle assembly in the longitudinal opening, wherein the needle guide is longitudinally compressible. [0023] Furthermore according to the present invention, a method comprises receiving, at an apparatus, a needle of a needle assembly in a longitudinal opening of a needle guide, and centering the needle of the needle assembly in the longitudinal opening, wherein the needle guide is longitudinally compressible. [0024] The apparatus may be a dispenser. In particular, the apparatus may be a drug delivery device such as a medical device configured to eject a drug agent (e.g. a dose of a medicament) such as an infusion device or an injection device, for instance an insulin injection pen. Injection devices may be used either by medical personnel or by patients themselves. As an example, type-1 and type-2 diabetes may be treated by patients themselves by injection of insulin doses, for example once or several times per day. [0025] For instance, the apparatus is a medical device configured to eject at least two drug agents from separate reservoirs comprising a first and a second medicament, respectively, but it is not limited thereto. Alternatively, the medical device is for instance a conventional medical device configured to eject a drug agent from a single reservoir such as Applicant's Solostar insulin injection pen. [0026] Alternatively, the apparatus may be a disposable part attachable to a dispenser such as a drug delivery device such as a medical device configured to eject a medicament. For instance, the apparatus is a dispense interface attachable to a medical device configured to eject a drug agent. A dispense interface may be configured to be in fluid communication with at least one reservoir of the medical device containing at least one medicament. For instance, the drug dispense interface is a type of outlet that allows the at least one medicament to exit the medical device. The dispense interface may comprise a valve arrangement. Such a valve arrangement may be configured to prevent contamination of the at least one medicament in the at least one reservoir. For instance, the valve arrangement is configured to prevent back flow of the at least one medicament when the medicament is delivered/ejected. [0027] Alternatively, the apparatus may be the needle guide. The needle guide may be (reversibly and/or irreversibly) attachable to a connecting part such as a connecting part of a dispense interface and/or a dispenser such as a drug delivery device. [0028] The needle-assembly may be a dose dispenser. For instance, the needle assembly is configured to be in fluid communication with a holding chamber of a dispense interface and/or at least one reservoir of a dispenser such as a drug delivery device. The reservoir may contain at least one fluid such as a medicament. [0029] For instance, the needle assembly is a double-ended needle assembly and/or a standard needle assembly. The needle assembly may comprise a needle, a needle hub and a removable protecting cover. The needle may be a double-ended needle. One end of the double ended needle may be configured to be inserted into a desired injection site before an injection. The other end of the double ended needle may be configured to pierce a septum of a connecting part such as a connecting part of a dispense interface and/or a drug delivery device as described above. The needle hub may be configured to attach the needle assembly to the connecting part such as a connecting part of the dispense interface and/or the dispenser such as the drug delivery device. For instance, the needle hub comprises an internal thread corresponding to an outer thread of the connecting part. [0030] According to the present invention, the needle guide is configured to receive a needle of the needle assembly in a longitudinal opening and to center the needle in the longitudinal opening. The needle may be considered to be centered in the longitudinal opening of the needle guide, when the longitudinal axis of the longitudinal opening and the longitudinal axis of the needle are equal, i.e. the needle and the longitudinal opening are coaxial. In particular, the needle may be considered to be centered in the longitudinal opening of the needle guide, when one end of the needle being in the longitudinal opening is in the center of a cross section of the longitudinal opening. [0031] For instance, when the needle assembly is received in the longitudinal opening, the needle assembly may be laterally secured in the longitudinal opening. For instance, a rim of the longitudinal opening is configured to engage with a corresponding recess of the needle assembly such that, when the rim of the longitudinal opening is in engagement with the corresponding recess of the needle assembly, the needle is centered in the longitudinal opening. Alternatively or additionally, the longitudinal opening may have a (circular) set-back configured to receive a rim of the needle assembly such that, when the rim of the needle resides on the setback of the longitudinal opening, the needle is centered in the longitudinal opening. [0032] Furthermore, according to the present invention, the needle guide is longitudinally compressible. In particular, the longitudinal opening of the needle guide may be longitudinally compressible. For instance, when a force is applied on the longitudinal opening of the needle guide in direction of the longitudinal axis of the longitudinal opening, the longitudinal length of the longitudinal opening of the needle guide is reduced. [0033] As an example, the needle guide is arranged at a connecting part of a dispense interface such that the longitudinal opening at least partially encompasses the connecting part of the dispense interface and an outlet of the connecting part is in the center of a cross section of the longitudinal opening. In this example, when a needle assembly is received in the longitudinal opening, one end of a needle of the needle assembly may be spaced from and centered on the outlet of the connecting part. The outlet of the connecting part may be an opening at the center of the connecting part and is configured to receive one end of a needle of the needle assembly. If the needle assembly is pushed in direction of the longitudinal axis of the longitudinal opening in order to attach the needle hub of the needle assembly to the connecting part of the dispense interface as described above, the needle assembly may be laterally secured in the longitudinal opening and the one end of the needle may straightly approach the outlet along the longitudinal axis of the longitudinal opening. [0034] For instance, the smallest diameter of the longitudinal opening (or of the longitudinally compressible portion thereof) may be at least a third, preferably at least a half, more preferably at least once or twice of the longitudinal length of the longitudinal opening. This is inter-alia advantageous to stablilize the needle guide, when the longitudinal opening is longitudinally compressed, and/or to allow the needle to straightly approach the outlet and/or to prevent a tilting of the needle, when the longitudinal opening is longitudinally compressed. [0035] For instance, the needle hub of the needle assembly is screwed on the connecting part of the dispense interface and thereby one end of a needle of the double-ended assembly straightly intrudes into the outlet of the connecting part of the dispense interface, pierces a septum of the dispense interface arranged at the outlet and resides in fluid communication with a holding chamber of the dispense interface. Therein, the needle guide centers the needle and prevents a tilting of the needle. In other words, the needle guide may preferably be configured to hold the needle in the center of the longitudinal opening, when the needle guide is longitudinally compressed, such that the needle guide allows the needle to straightly approach the outlet and/or to prevent a tilting of the needle. [0036] Accordingly, the risk of a collision of the needle with side-walls of the holding chamber and/or the outlet is significantly reduced, such that the cross-sectional inner diameter of the holding-chamber and/or the outlet may correspond to the outer diameter of the needle, for instance the inner diameter of the holding-chamber and/or the outlet is only slightly larger (e.g. 5%, 10% or 25% larger) than the outer diameter of the needle. Alternatively or additionally, the length of the needle and/or the holding chamber can accordingly be decreased such that the one end of the needle of the needle assembly may be completely inside the needle hub and may intrude into the outlet after the needle hub touches the connecting part. [0037] The present invention is inter-alia advantageous in order to facilitate attaching a dose dispenser to a connecting part such as a connecting part of a dispense interface and/or a dispenser such as a drug delivery device. Furthermore, the present invention is inter-alia advantageous in order to minimize the liquid dead volume in a dispense interface and/or in front of a reservoir of a dispenser such as a drug delivery device. [0038] In the following, features and embodiments (exhibiting further features) of the present invention will be described, which are understood to equally apply to the apparatus and the method as described above. These single features/embodiments are considered to be exemplary and non-limiting, and to be respectively combinable independently from other disclosed features/embodiments of the apparatus and the method as described above. Nevertheless, these features/embodiments shall also be considered to be disclosed in all possible combinations with each other and with the apparatus and the method as described above. For instance, a mentioning that an apparatus according to the present invention is configured to perform a certain action should be understood to also disclose an according method step of the method according to the present invention. [0039] According to an embodiment of the present invention, the longitudinal opening has a circular cross-section and/or is cylindrical. Alternatively or additionally, the cross-section of the longitudinal opening may be elliptical and/or round. The longitudinal opening may be a cylinder having a longitudinal opening (e.g. a through opening). [0040] For instance, standard needle assemblies typically also have a circular cross-section. For instance, an inner diameter of the longitudinal opening may be adapted to an outer diameter of a standard needle assembly. In particular, the inner diameter at a rim of the longitudinal opening may be adapted to an outer diameter of a rim of the standard needle assembly. This embodiment is inter-alia advantageous to enable receiving a standard needle assembly in the longitudinal opening. [0041] According to an embodiment of the present invention, the longitudinal opening is defined by a longitudinally compressible lateral surface. As described above, when a force is for instance applied on the longitudinal opening of the needle guide in direction of the longitudinal axis of the longitudinal opening, the longitudinal length of the lateral surface defining the longitudinal opening of the needle guide is reduced. This embodiment is inter-alia advantageous in order to allow a longitudinal compression of the longitudinal opening. [0042] According to an embodiment of the present invention, the lateral surface is foldable. As an example, the lateral surface is (only) foldable in direction of the longitudinal axis of the longitudinal opening such that (only or mainly) the longitudinal stiffness of the lateral surface is decreased. In this example, when a needle assembly is received in the longitudinal opening and is pushed at an angle in direction of the longitudinal axis of the longitudinal opening, the lateral stiffness of the lateral surface may at least partially prevent a tilting/jamming of the needle. [0043] This embodiment is inter-alia advantageous in order to define a preferred direction for the compression of the longitudinal opening and/or to prevent a jamming/tilting of the needle of the needle assembly. [0044] According to an embodiment of the present invention, the foldable lateral surface is formed like bellows. The cross-section of the bellows like lateral surface may be “V-shaped”. For instance, the lateral surface has the property of bending and ceasing. Alternatively or additionally, the foldable lateral surface is wavelike. As described above, this embodiment is inter-alia advantageous in order to define a preferred direction for the compression and/or to prevent a jamming/tilting of the needle of the needle assembly. [0045] According to an embodiment of the present invention, the lateral surface is made from an elastic material. [0046] For instance, the needle guide is made from elastic plastics such as injection moldable elastic plastics. [0047] The elasticity of the material may cause an elastic counterforce, when the longitudinal opening and/or the lateral surface thereof is compressed. For instance, the compressed longitudinal opening, like a compressed spring washer, secures a screw connection between a needle hub of the needle assembly and a connecting part of a dispense interface and/or a dispenser such as a drug delivery device. [0048] Furthermore, the elasticity of the material may also cause an elastic counterforce, when a needle assembly is received in the longitudinal opening and is pushed at an angle in direction of the longitudinal axis of the longitudinal opening. [0049] This embodiment is inter-alia advantageous to secure a connection between a needle hub of the needle assembly and a connecting part and/or to prevent a jamming/tilting of the needle. [0050] According to an embodiment of the present invention, the lateral surface has at least one longitudinal slit. The slit may allow to reversibly spread (i.e. enlarge) the longitudinal opening. This embodiment is inter-alia advantageous to reversibly attach the needle guide to a connecting part of a dispense interface and/or a dispenser such as a drug delivery device and/or to receive the needle assembly in the longitudinal opening. [0051] According to an embodiment of the present invention, the longitudinal opening has a circular set-back configured to receive a rim of the needle assembly. The set-back may be arranged in a plane perpendicular to the longitudinal axis of the longitudinal opening. For instance, the lateral surface of the longitudinal opening has a circular set-back such that the inner diameter of the longitudinal opening is enlarged at the set-back. For instance, the enlarged inner diameter may correspond to the outer diameter of the rim of the needle assembly. For instance, the set-back and/or the longitudinal opening is configured to form a lateral form fit with the needle assembly. The needle assembly may be a standard needle assembly. As described above, this embodiment is inter-alia advantageous to center the needle of the needle assembly and to secure the needle assembly laterally. [0052] Alternatively or additionally, the longitudinal opening may have a circular notch configured to receive a rim of the needle assembly. In this case, the diameter of the longitudinal opening may be spreadable to allow receiving the rim of the needle assembly in the circular notch. The needle assembly may be (laterally and longitudinally) secured in the longitudinal opening. For instance, the notch and/or the longitudinal opening is configured to form a longitudinal and lateral form fit with the needle assembly. This embodiment is inter-alia advantageous to attach the needle assembly to the needle guide prior to attaching the needle guide to a connecting part of dispenser interface and/or a dispenser such as a drug delivery device or the like. [0053] According to an embodiment of the present invention, the needle guide is configured to encompass a connecting part of a medical device configured to eject a medicament. The medical device may be a drug delivery device as described above. [0054] As described above, the longitudinal opening may be configured to at least partially encompass the connecting part of the medical device such that an outlet of the connecting part is in the center of a cross section of the longitudinal opening. The longitudinal opening may be a through opening. For instance, the longitudinal opening is configured to at least partially receive at one end the connecting part of the medical device and at the other end the needle assembly. This embodiment is inter-alia advantageous to allow a reversible or irreversible attachment of the needle guide to the connecting part of the medical device. [0055] Alternatively, as described above, the longitudinal opening may at least partially encompass the connecting part of the medical device such that an outlet of the connecting part is in the center of a cross section of the longitudinal opening. For instance, the needle guide is irreversibly attached to the connecting part of the medical device and/or the needle guide and the connecting part of the medical device are integrally formed. [0056] According to an embodiment of the present invention, the apparatus is attachable to the medical device. In particular, the needle guide is (reversibly or irreversibly) attachable to the medical device. For instance, the medical device and the needle guide comprise mating attachment means configured to form a frictional fit, a form fit and/or an interference fit. Examples of mating attachment means include snap locks, snap fits, snap rings, keyed slots, threads and any combinations thereof. Examples of mating attachment means include snap locks, snap fits, snap rings, keyed slots, threads and any combinations thereof. Alternatively or additionally, the apparatus may be configured to be glued to the medical device. [0057] When the needle guide is attached to the medical device, the longitudinal opening may at least partially encompass a connecting part of the medical device and an outlet of the connecting part may be in the center of a cross section of the longitudinal opening. The medical device may be a drug delivery device as described above. [0058] This embodiment is inter-alia advantageous to allow an attachment of the needle guide to the connecting part of the medical device. [0059] According to an embodiment of the present invention, the apparatus is a medical device configured to eject a medicament, wherein the needle guide encompasses a connecting part of the medical device. The medical device may be a drug delivery device as described above. The longitudinal opening may at least partially encompass the connecting part of the medical device such that an outlet of the connecting part is in the center of a cross section of the longitudinal opening. [0060] According to an embodiment of the present invention, a needle hub of the needle assembly is configured to be attached to the connecting part of the medical device. In particular, the needle assembly may be configured to be reversibly attached to the connecting part of the medical device. The needle hub and the connecting part may comprise mating attachment means configured to form a frictional fit, a form fit and/or an interference fit. Examples of mating attachment means include snap locks, snap fits, snap rings, keyed slots, threads and any combinations thereof. For instance, the needle hub comprises an internal thread corresponding to an outer thread of the connecting part. [0061] This embodiment is inter-alia advantageous to allow a reversible attachment of the needle assembly to the connecting part of the medical device. [0062] According to an embodiment of the present invention, one end of a needle of the needle assembly is configured to intrude into an outlet of the connecting part and to pierce a septum of the medical device. For instance, a needle hub of the needle assembly is screwed on the connecting part of the dispense interface and/or the medical device and thereby one end of a needle of the double-ended assembly intrudes into an outlet of the connecting part of the dispense interface, pierces a septum arranged at the outlet and resides in fluid communication with a holding chamber of the dispense interface and/or a reservoir of the medical device. [0063] According to an embodiment of the present invention, the method comprises longitudinally compressing the needle guide, attaching the needle assembly to a connecting part of the medical device, intruding the needle of the needle assembly into an outlet of the needle hub, and piercing a septum of the medical device. BRIEF DESCRIPTION OF THE DRAWINGS [0064] These as well as other advantages of various aspects of the present invention will become apparent to those of ordinary skill in the art by reading the following detailed description, with appropriate reference to the accompanying drawings, in which: [0065] FIG. 1 illustrates a perspective view of the delivery device illustrated in FIGS. 1 a and 1 b with an end cap of the device removed; [0066] FIG. 2 illustrates a perspective view of the delivery device distal end showing the cartridge; [0067] FIG. 3 illustrates a perspective view of the cartridge holder illustrated in FIG. 1 with one cartridge retainer in an open position; [0068] FIG. 4 illustrates a dispense interface and a dose dispenser that may be removably attached on a distal end of the delivery device illustrated in FIG. 1 ; [0069] FIG. 5 illustrates the dispense interface and the dose dispenser illustrated in FIG. 4 attached on a distal end of the delivery device illustrated in FIG. 1 ; [0070] FIG. 6 illustrates one arrangement of the dose dispenser that may be mounted on a distal end of the delivery device; [0071] FIG. 7 illustrates a perspective view of the dispense interface illustrated in FIG. 4 ; [0072] FIG. 8 illustrates another perspective view of the dispense interface illustrated in FIG. 4 ; [0073] FIG. 9 illustrates a cross-sectional view of the dispense interface illustrated in FIG. 4 ; [0074] FIG. 10 illustrates an exploded view of the dispense interface illustrated in FIG. 4 ; [0075] FIG. 11 illustrates a cross-sectional view of the dispense interface and dose dispenser attached to a drug delivery device, such as the device illustrated in FIG. 1 ; [0076] FIG. 12 illustrates an arrangement of a needle guide; [0077] FIG. 13 illustrates a dispense interface that may be removably mounted on a distal end of the delivery device illustrated in FIG. 1 and a needle assembly that may be removably mounted on the dispense interface by use of a needle guide; [0078] FIG. 14 illustrates a method for attaching a needle assembly to a dispense interface by use of a needle guide; [0079] FIG. 15 illustrates a cross-sectional view of the dispense interface, needle guide and dose dispenser attached to a drug delivery device, such as the device illustrated in FIG. 1 ; DETAILED DESCRIPTION [0080] The drug delivery device illustrated in FIG. 1 comprises a main body 14 that extends from a proximal end 16 to a distal end 15 . At the distal end 15 , a removable end cap or cover 18 is provided. This end cap 18 and the distal end 15 of the main body 14 work together to provide a snap fit or form fit connection so that once the cover 18 is slid onto the distal end 15 of the main body 14 , this frictional fit between the cap and the main body outer surface 20 prevents the cover from inadvertently falling off the main body. [0081] The main body 14 contains a micro-processor control unit, an electro-mechanical drive train, and at least two medicament reservoirs. When the end cap or cover 18 is removed from the device 10 (as illustrated in FIG. 1 ), a dispense interface 200 is mounted to the distal end 15 of the main body 14 , and a dose dispenser (e.g., a needle assembly) is attached to the interface. The drug delivery device 10 can be used to administer a computed dose of a second medicament (secondary drug compound) and a variable dose of a first medicament (primary drug compound) through a single needle assembly, such as a double ended needle assembly. [0082] A control panel region 60 is provided near the proximal end of the main body 14 . Preferably, this control panel region 60 comprises a digital display 80 along with a plurality of human interface elements that can be manipulated by a user to set and inject a combined dose. In this arrangement, the control panel region comprises a first dose setting button 62 , a second dose setting button 64 and a third button 66 designated with the symbol “OK.” In addition, along the most proximal end of the main body, an injection button 74 is also provided (not visible in the perspective view of FIG. 1 ). [0083] The cartridge holder 40 can be removably attached to the main body 14 and may contain at least two cartridge retainers 50 and 52 . Each retainer is configured so as to contain one medicament reservoir, such as a glass cartridge. Preferably, each cartridge contains a different medicament. [0084] In addition, at the distal end of the cartridge holder 40 , the drug delivery device illustrated in FIG. 1 includes a dispense interface 200 . As will be described in relation to FIG. 4 , in one arrangement, this dispense interface 200 includes a main outer body 212 that is removably attached to a distal end 42 of the cartridge housing 40 . As can be seen in FIG. 1 , a distal end 214 of the dispense interface 200 preferably comprises a connecting part such as needle hub 216 . This needle hub 216 may be configured so as to allow a dose dispenser, such as a conventional pen type injection needle assembly, to be removably mounted to the drug delivery device 10 . The needle hub 216 has an outer diameter 217 at the end 219 . [0085] Once the device is turned on, the digital display 80 shown in FIG. 1 illuminates and provides the user certain device information, preferably information relating to the medicaments contained within the cartridge holder 40 . For example, the user is provided with certain information relating to both the primary medicament (Drug A) and the secondary medicament (Drug B). [0086] As shown in FIG. 3 , the first and a second cartridge retainers 50 , 52 comprise hinged cartridge retainers. These hinged retainers allow user access to the cartridges. FIG. 3 illustrates a perspective view of the cartridge holder 40 illustrated in FIG. 1 with the first hinged cartridge retainer 50 in an open position. FIG. 3 illustrates how a user might access the first cartridge 90 by opening up the first retainer 50 and thereby having access to the first cartridge 90 . [0087] As mentioned above when discussing FIG. 1 , a dispense interface 200 is coupled to the distal end of the cartridge holder 40 . FIG. 4 illustrates a flat view of the dispense interface 200 unconnected to the distal end of the cartridge holder 40 . A dose dispenser or needle assembly that may be used with the interface 200 is also illustrated and is provided in a protective outer cap 420 . The protective cover 420 has a rim 421 and an outer diameter 422 at the rim 421 . [0088] In FIG. 5 , the dispense interface 200 illustrated in FIG. 4 is shown coupled to the cartridge holder 40 . The axial attachment means between the dispense interface 200 and the cartridge holder 40 can be any known axial attachment means to those skilled in the art, including snap locks, snap fits, snap rings, keyed slots, and combinations of such connections. The connection or attachment between the dispense interface and the cartridge holder may also contain additional features (not shown), such as connectors, stops, splines, ribs, grooves, pips, clips and the like design features, that ensure that specific hubs are attachable only to matching drug delivery devices. Such additional features would prevent the insertion of a non-appropriate secondary cartridge to a non-matching injection device. [0089] FIG. 5 also illustrates the needle assembly 400 and protective cover 420 coupled to the distal end of the dispense interface 200 that may be screwed onto the needle hub of the interface 200 . FIG. 6 illustrates a cross sectional view of the double ended needle assembly 402 mounted on the dispense interface 200 in FIG. 5 . [0090] The needle assembly 400 illustrated in FIG. 6 comprises a double ended needle 406 and a hub 401 . The double ended needle or cannula 406 is fixedly mounted in a needle hub 401 . This needle hub 401 comprises a circular disk shaped element which has along its periphery a circumferential depending sleeve 403 . Along an inner wall of this hub member 401 , a thread 404 is provided. This thread 404 allows the needle hub 401 to be screwed onto the needle hub 216 of dispense interface 200 which, in one preferred arrangement, is provided with a corresponding outer thread along a distal hub. At a center portion of the hub element 401 there is provided a protrusion 402 . This protrusion 402 projects from the hub in an opposite direction of the sleeve member. A double ended needle 406 is mounted centrally through the protrusion 402 and the needle hub 401 . This double ended needle 406 is mounted such that a first or distal piercing end 405 of the double ended needle forms an injecting part for piercing an injection site (e.g., the skin of a user). [0091] Similarly, a second or proximal piercing end 407 of the needle assembly 400 protrudes from an opposite side of the circular disc so that it is concentrically surrounded by the sleeve 403 . In one needle assembly arrangement, the second or proximal piercing end 406 may be shorter than the sleeve 403 so that this sleeve to some extent protects the pointed end of the back sleeve. The needle cover cap 420 illustrated in FIGS. 4 and 5 provides a form fit around the outer surface 403 of the hub 401 . [0092] Referring now to FIGS. 4 to 11 , one preferred arrangement of this interface 200 will now be discussed. In this one preferred arrangement, this interface 200 comprises: [0093] a. a main outer body 210 , [0094] b. an first inner body 220 , [0095] c. a second inner body 230 , [0096] d. a first piercing needle 240 , [0097] e. a second piercing needle 250 , [0098] f. a valve seal 260 , and [0099] g. a septum 270 . [0100] The main outer body 210 comprises a main body proximal end 212 and a main body distal end 214 . At the proximal end 212 of the outer body 210 , a connecting member is configured so as to allow the dispense interface 200 to be attached to the distal end of the cartridge holder 40 . Preferably, the connecting member is configured so as to allow the dispense interface 200 to be removably connected the cartridge holder 40 . In one preferred interface arrangement, the proximal end of the interface 200 is configured with an upwardly extending wall 218 having at least one recess. For example, as may be seen from FIG. 8 , the upwardly extending wall 218 comprises at least a first recess 217 and a second recess 219 . [0101] Preferably, the first and the second recesses 217 , 219 are positioned within this main outer body wall so as to cooperate with an outwardly protruding member located near the distal end of the cartridge housing 40 of the drug delivery device 10 . For example, this outwardly protruding member 48 of the cartridge housing may be seen in FIGS. 4 and 5 . A second similar protruding member is provided on the opposite side of the cartridge housing. As such, when the interface 200 is axially slid over the distal end of the cartridge housing 40 , the outwardly protruding members will cooperate with the first and second recess 217 , 219 to form an interference fit, form fit, or snap lock. Alternatively, and as those of skill in the art will recognize, any other similar connection mechanism that allows for the dispense interface and the cartridge housing 40 to be axially coupled could be used as well. [0102] The main outer body 210 and the distal end of the cartridge holder 40 act to form an axially engaging snap lock or snap fit arrangement that could be axially slid onto the distal end of the cartridge housing. In one alternative arrangement, the dispense interface 200 may be provided with a coding feature so as to prevent inadvertent dispense interface cross use. That is, the inner body of the hub could be geometrically configured so as to prevent an inadvertent cross use of one or more dispense interfaces. [0103] A mounting hub is provided at a distal end of the main outer body 210 of the dispense interface 200 . Such a mounting hub can be configured to be releasably connected to a needle assembly. As just one example, this connecting means 216 may comprise an outer thread that engages an inner thread provided along an inner wall surface of a needle hub of a needle assembly, such as the needle assembly 400 illustrated in FIG. 6 . Alternative releasable connectors may also be provided such as a snap lock, a snap lock released through threads, a bayonet lock, a form fit, or other similar connection arrangements. [0104] The dispense interface 200 further comprises a first inner body 220 . Certain details of this inner body are illustrated in FIG. 8-11 . Preferably, this first inner body 220 is coupled to an inner surface 215 of the extending wall 218 of the main outer body 210 . More preferably, this first inner body 220 is coupled by way of a rib and groove form fit arrangement to an inner surface of the outer body 210 . For example, as can be seen from FIG. 9 , the extending wall 218 of the main outer body 210 is provided with a first rib 213 a and a second rib 213 b . This first rib 213 a is also illustrated in FIG. 10 . These ribs 213 a and 213 b are positioned along the inner surface 215 of the wall 218 of the outer body 210 and create a form fit or snap lock engagement with cooperating grooves 224 a and 224 b of the first inner body 220 . In a preferred arrangement, these cooperating grooves 224 a and 224 b are provided along an outer surface 222 of the first inner body 220 . [0105] In addition, as can be seen in FIG. 8-10 , a proximal surface 226 near the proximal end of the first inner body 220 may be configured with at least a first proximally positioned piercing needle 240 comprising a proximal piercing end portion 244 . Similarly, the first inner body 220 is configured with a second proximally positioned piercing needle 250 comprising a proximally piercing end portion 254 . Both the first and second needles 240 , 250 are rigidly mounted on the proximal surface 226 of the first inner body 220 . [0106] Preferably, this dispense interface 200 further comprises a valve arrangement. Such a valve arrangement could be constructed so as to prevent cross contamination of the first and second medicaments contained in the first and second reservoirs, respectively. A preferred valve arrangement may also be configured so as to prevent back flow and cross contamination of the first and second medicaments. [0107] In one preferred system, dispense interface 200 includes a valve arrangement in the form of a valve seal 260 . Such a valve seal 260 may be provided within a cavity 231 defined by the second inner body 230 , so as to form a holding chamber 280 . Preferably, cavity 231 resides along an upper surface of the second inner body 230 . This valve seal comprises an upper surface that defines both a first fluid groove 264 and second fluid groove 266 . For example, FIG. 9 illustrates the position of the valve seal 260 , seated between the first inner body 220 and the second inner body 230 . During an injection step, this seal valve 260 helps to prevent the primary medicament in the first pathway from migrating to the secondary medicament in the second pathway, while also preventing the secondary medicament in the second pathway from migrating to the primary medicament in the first pathway. Preferably, this seal valve 260 comprises a first non-return valve 262 and a second non-return valve 268 . As such, the first non-return valve 262 prevents fluid transferring along the first fluid pathway 264 , for example a groove in the seal valve 260 , from returning back into this pathway 264 . Similarly, the second non-return valve 268 prevents fluid transferring along the second fluid pathway 266 from returning back into this pathway 266 . [0108] Together, the first and second grooves 264 , 266 converge towards the non-return valves 262 and 268 respectively, to then provide for an output fluid path or a holding chamber 280 . This holding chamber 280 is defined by an inner chamber defined by a distal end of the second inner body both the first and the second non return valves 262 , 268 along with a pierceable septum 270 . As illustrated, this pierceable septum 270 is positioned between a distal end portion of the second inner body 230 and an inner surface defined by the needle hub of the main outer body 210 . [0109] The holding chamber 280 terminates at an outlet of the interface 200 . This outlet 290 is preferably centrally located in the needle hub 216 of the interface 200 and assists in maintaining the pierceable seal 270 in a stationary position. As such, when a double ended needle assembly is attached to the needle hub of the interface (such as the double ended needle illustrated in FIG. 6 ), the output fluid path allows both medicaments to be in fluid communication with the attached needle assembly. [0110] The hub interface 200 further comprises a second inner body 230 . As can be seen from FIG. 9 , this second inner body 230 has an upper surface that defines a recess, and the valve seal 260 is positioned within this recess. Therefore, when the interface 200 is assembled as shown in FIG. 9 , the second inner body 230 will be positioned between a distal end of the outer body 210 and the first inner body 220 . Together, second inner body 230 and the main outer body hold the septum 270 in place. The distal end of the inner body 230 may also form a cavity or holding chamber that can be configured to be fluid communication with both the first groove 264 and the second groove 266 of the valve seal. [0111] Axially sliding the main outer body 210 over the distal end of the drug delivery device attaches the dispense interface 200 to the multi-use device. In this manner, a fluid communication may be created between the first needle 240 and the second needle 250 with the primary medicament of the first cartridge and the secondary medicament of the second cartridge, respectively. [0112] FIG. 11 illustrates the dispense interface 200 after it has been mounted onto the distal end 42 of the cartridge holder 40 of the drug delivery device 10 illustrated in FIG. 1 . A double ended needle 400 is also mounted to the distal end of this interface. The cartridge holder 40 is illustrated as having a first cartridge containing a first medicament and a second cartridge containing a second medicament. [0113] When the interface 200 is first mounted over the distal end of the cartridge holder 40 , the proximal piercing end 244 of the first piercing needle 240 pierces the septum of the first cartridge 90 and thereby resides in fluid communication with the primary medicament 92 of the first cartridge 90 . A distal end of the first piercing needle 240 will also be in fluid communication with a first fluid path groove 264 defined by the valve seal 260 . [0114] Similarly, the proximal piercing end 254 of the second piercing needle 250 pierces the septum of the second cartridge 100 and thereby resides in fluid communication with the secondary medicament 102 of the second cartridge 100 . A distal end of this second piercing needle 250 will also be in fluid communication with a second fluid path groove 266 defined by the valve seal 260 . [0115] FIG. 11 illustrates a preferred arrangement of such a dispense interface 200 that is coupled to a distal end 15 of the main body 14 of drug delivery device 10 . Preferably, such a dispense interface 200 is removably coupled to the cartridge holder 40 of the drug delivery device 10 . [0116] As illustrated in FIG. 11 , the dispense interface 200 is coupled to the distal end of a cartridge housing 40 . This cartridge holder 40 is illustrated as containing the first cartridge 90 containing the primary medicament 92 and the second cartridge 100 containing the secondary medicament 102 . Once coupled to the cartridge housing 40 , the dispense interface 200 essentially provides a mechanism for providing a fluid communication path from the first and second cartridges 90 , 100 to the common holding chamber 280 . This holding chamber 280 is illustrated as being in fluid communication with a dose dispenser. Here, as illustrated, this dose dispenser comprises the double ended needle assembly 400 . As illustrated, the proximal end of the double ended needle assembly is in fluid communication with the chamber 280 . [0117] In one preferred arrangement, the dispense interface is configured so that it attaches to the main body in only one orientation, that is it is fitted only one way round. As such as illustrated in FIG. 11 , once the dispense interface 200 is attached to the cartridge holder 40 , the primary needle 240 can only be used for fluid communication with the primary medicament 92 of the first cartridge 90 and the interface 200 would be prevented from being reattached to the holder 40 so that the primary needle 240 could now be used for fluid communication with the secondary medicament 102 of the second cartridge 100 . Such a one way around connecting mechanism may help to reduce potential cross contamination between the two medicaments 92 and 102 . [0118] FIG. 12 a to c illustrate an arrangement of a needle guide 500 . The needle guide 500 has a longitudinal through opening 501 . The opening 501 has a round cross section and is defined by a foldable lateral surface 502 . The foldable lateral surface 502 is in direction of the longitudinal axis 503 of the opening 501 bellows like and has a longitudinal cross section comprising two sequentially arranged “V-shaped” portions. The foldable lateral surface 502 allows a reversible compression of the opening 502 in direction of the axis 503 . [0119] A rim 504 is arranged at one end of the opening 501 and a setback 505 is arranged at the rim 504 . At the setback 505 the opening 501 has an inner diameter 506 . The inner diameter 506 corresponds (e.g. is equal to or less than or, alternatively, equal to or not less than) to the outer diameter 422 at the rim 421 of the needle assembly 400 illustrated in FIG. 4 . At the other end of the opening 501 , a basis 507 is arranged. At the basis 507 the opening 501 has an inner diameter 508 . The inner diameter 508 corresponds (e.g. is equal to or less than) to the outer diameter at the end 219 of the needle hub 216 of the dispense interface 200 illustrated in FIG. 4 . [0120] The needle guide 500 is made from an elastic material such as elastic plastics and the opening 501 has a longitudinal slit 509 which allows to spread the opening 501 and to enlarge the inner diameters (e.g. diameters 506 , 508 ) of the opening 501 . [0121] FIG. 13 illustrates the dispense interface 200 illustrated in FIGS. 7 to 10 that may be removably attached to the distal end 42 of the delivery device 10 illustrated in FIG. 1 and the needle assembly 400 illustrated in FIG. 6 that may be removably attached on the dispense interface 200 by use of the needle guide 500 illustrated in FIG. 12 . [0122] As illustrated in FIG. 13 the needle guide 500 is arranged between the needle assembly 400 and the dispense interface 200 . Therein, base 507 of the needle guide 500 is oriented towards the dispense interface 200 and the rim 504 of the needle guide 500 is oriented towards the needle assembly 400 and, additionally, the longitudinal axis 503 of the needle guide 500 is also the longitudinal axis of the drug delivery device 10 , the dispense interface 200 and the needle assembly 400 . [0123] The inner diameter 508 at the base 507 of the needle guide 500 is equal to or less than the outer diameter 217 at the end 219 of the needle hub 216 of the dispense interface 200 . Furthermore, the inner diameter 506 at the setback 505 (not shown) of the needle guide 500 is equal to or less than the outer diameter 422 at the rim 421 of the needle assembly 400 . [0124] The needle assembly 400 may be attached to the dispense interface 200 by use of the needle guide 500 as follows. [0125] FIG. 14 illustrates a method 700 for attaching the needle assembly 400 to the dispense interface 200 by use of the needle guide 500 . [0126] In a step 701 , the opening 501 of the needle guide 500 is spread by spreading the slit 509 of the opening 501 and thereby the inner diameters of the opening 501 are enlarged. In particular, the inner diameter 508 of the spread opening 501 is enlarged. [0127] In a step 702 , the needle hub 216 of the dispense interface 200 is received in the spread opening 501 ; and, in a step 703 , the spreading is released. After releasing the spread, the opening 501 returns to its natural shape such that the inner diameter 508 of the spread opening 501 is equal to or less than the outer diameter 217 at the end 219 of the needle hub 216 . Accordingly, the needle guide 500 is attached to the dispense interface 200 by forming a press fit or form fit connection with the end 219 of the of the needle hub 216 such that the opening 501 encompasses the needle hub 216 of the dispense interface 200 and the outlet 290 of the needle hub 216 is in the center of a cross section of the opening 501 . Alternatively or additionally, the base 507 of the needle guide may be bonded (e.g. glued) to the surface of the dispense interface. [0128] In a step 704 , the needle assembly 400 is at least partially received in the opening 501 . After at least partially receiving the needle assembly 400 in the opening 501 , the rim 421 of the protective cover 420 resides on the setback 505 of the opening 501 and is laterally secured by the rim 504 of the opening 501 such that the double-ended needle 406 of the needle assembly 400 is centered in the opening. In particular, the piercing end 407 of the double-ended needle 406 is spaced from and centered on the outlet 290 of the needle hub 216 . For instance, the needle assembly 400 at least partially forms a form fit connection with the opening 501 . [0129] In a step 705 , the needle assembly 400 is pushed towards the dispense interface 200 along the longitudinal axis 503 . Since the rim 421 of the protective cap 420 of the needle assembly resides on the setback 505 of the opening 501 , the rim 504 of the opening 501 is also pushed towards the dispense interface 200 along the longitudinal axis 503 such that the lateral surface 502 of the opening 501 is folded and the opening 501 is compressed. Therein, the rim 421 of the protective cap 420 of the needle assembly remains on the setback 505 and is laterally secured by the rim 504 of the opening 501 such that the piercing end 407 of the double-ended needle 406 straightly approaches the outlet 290 along the axis 503 . [0130] When the needle hub 401 of the needle assembly 400 touches the needle hub 216 of the dispense interface, in a step 706 , the needle assembly 400 is attached to the dispense interface 200 . [0131] Therein, the rim 421 of the protective cap 420 of the needle assembly still remains on the setback 505 and is laterally secured by the rim 504 of the opening 501 . As described above, the internal thread 404 of the needle hub 401 of the needle assembly is screwed on the outer thread 218 of the needle hub 216 of the dispense interface 200 and thereby the piercing end 407 of the double-ended needle 406 intrudes into the outlet 290 of the needle hub 216 , pierces the septum 270 arranged at the outlet 290 and resides in fluid communication with the holding chamber 280 of the dispense interface 200 . The holding chamber may be in fluid communication with the first and second proximal needle. [0132] Accordingly, the risk of a collision of the double-ended needle 406 with side-walls of the holding chamber 280 is significantly reduced, such that the cross-sectional inner diameter of the holding-chamber 280 may correspond to the outer diameter of the double ended needle 406 . [0133] Alternatively, the needle assembly 400 may firstly be received in the opening 501 of the needle guide 500 and, thereafter, the needle guide 500 may be attached to the dispense interface 200 . For instance, firstly the steps 704 to 706 and, thereafter, the steps 701 - 703 may be performed. [0134] FIG. 15 illustrates a cross-sectional view of the dispense interface 200 illustrated in FIGS. 7-10 , needle guide 500 illustrated in FIG. 12 and needle assembly 400 illustrated in FIG. 6 attached to a drug delivery device 10 illustrated in FIG. 1 . At this point, it is mainly referred to the above description of the arrangement illustrated in FIG. 11 and, basically, the differences are described only. [0135] As illustrated in FIG. 15 , the needle hub 401 of the needle assembly 400 is screwed onto the needle hub 216 of the dispense interface 200 . Therein, the sleeve 403 of the needle hub 401 resides on the setback 505 of the needle guide 500 and longitudinally compresses the opening 501 such that the lateral surface 502 of the longitudinal opening is folded. In response to the compression, an elastic counterforce in the direction of arrow 1000 is caused by the lateral surface 502 . This counterforce may secure the screw connection between the dispense interface 200 and the needle assembly 400 . [0136] The present invention is inter-alia advantageous in order to facilitate attaching needle assembly 400 to the needle hub 216 of the dispense interface 200 . Furthermore, the present invention is inter-alia advantageous in order to minimize the liquid dead volume in the dispense interface and/or in front of the cartridges 90 and 100 of the drug delivery device 10 and to secure the screw connection between the dispense interface 200 and the needle assembly 400 . [0137] The term “drug” or “medicament”, as used herein, means a pharmaceutical formulation containing at least one pharmaceutically active compound, [0138] wherein in one embodiment the pharmaceutically active compound has a molecular weight up to 1500 Da and/or is a peptide, a proteine, a polysaccharide, a vaccine, a DNA, a RNA, an enzyme, an antibody or a fragment thereof, a hormone or an oligonucleotide, or a mixture of the above-mentioned pharmaceutically active compound, [0139] wherein in a further embodiment the pharmaceutically active compound is useful for the treatment and/or prophylaxis of diabetes mellitus or complications associated with diabetes mellitus such as diabetic retinopathy, thromboembolism disorders such as deep vein or pulmonary thromboembolism, acute coronary syndrome (ACS), angina, myocardial infarction, cancer, macular degeneration, inflammation, hay fever, atherosclerosis and/or rheumatoid arthritis, [0140] wherein in a further embodiment the pharmaceutically active compound comprises at least one peptide for the treatment and/or prophylaxis of diabetes mellitus or complications associated with diabetes mellitus such as diabetic retinopathy, [0141] wherein in a further embodiment the pharmaceutically active compound comprises at least one human insulin or a human insulin analogue or derivative, glucagon-like peptide (GLP-1) or an analogue or derivative thereof, or exedin-3 or exedin-4 or an analogue or derivative of exedin-3 or exedin-4. [0142] Insulin analogues are for example Gly(A21), Arg(B31), Arg(B32) human insulin; Lys(B3), Glu(B29) human insulin; Lys(B28), Pro(B29) human insulin; Asp(B28) human insulin; human insulin, wherein proline in position B28 is replaced by Asp, Lys, Leu, Val or Ala and wherein in position B29 Lys may be replaced by Pro; Ala(B26) human insulin; Des(B28-B30) human insulin; Des(B27) human insulin and Des(B30) human insulin. [0143] Insulin derivates are for example B29-N-myristoyl-des(B30) human insulin; B29-N-palmitoyl-des(B30) human insulin; B29-N-myristoyl human insulin; B29-N-palmitoyl human insulin; B28-N-myristoyl LysB28ProB29 human insulin; B28-N-palmitoyl-LysB28ProB29 human insulin; B30-N-myristoyl-ThrB29LysB30 human insulin; B30-N-palmitoyl-ThrB29LysB30 human insulin; B29-N—(N-palmitoyl-Y-glutamyl)-des(B30) human insulin; B29-N—(N-lithocholyl-Y-glutamyl)-des(B30) human insulin; B29-N-(ω-carboxyheptadecanoyl)-des(B30) human insulin and B29-N-(ω-carboxyhepta decanoyl) human insulin. [0144] Exendin-4 for example means Exendin-4(1-39), a peptide of the sequence H His-Gly-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Leu-Ser-Lys-Gln-Met-Glu-Glu-Glu-Ala-Val-Arg-Leu-Phe-Ile-Glu-Trp-Leu-Lys-Asn-Gly-Gly-Pro-Ser-Ser-Gly-Ala-Pro-Pro-Pro-Ser-NH2. [0145] Exendin-4 derivatives are for example selected from the following list of compounds: [0146] H-(Lys)4-des Pro36, des Pro37 Exendin-4(1-39)-NH2, [0147] H-(Lys)5-des Pro36, des Pro37 Exendin-4(1-39)-NH2, [0148] des Pro36 [Asp28] Exendin-4(1-39), [0149] des Pro36 [IsoAsp28] Exendin-4(1-39), [0150] des Pro36 [Met(O)14, Asp28] Exendin-4(1-39), [0151] des Pro36 [Met(O)14, IsoAsp28] Exendin-4(1-39), [0152] des Pro36 [Trp(O2)25, Asp28] Exendin-4(1-39), [0153] des Pro36 [Trp(O2)25, IsoAsp28] Exendin-4(1-39), [0154] des Pro36 [Met(O)14 Trp(O2)25, Asp28] Exendin-4(1-39), [0155] des Pro36 [Met(O)14 Trp(O2)25, IsoAsp28] Exendin-4(1-39); or [0156] des Pro36 [Asp28] Exendin-4(1-39), [0157] des Pro36 [IsoAsp28] Exendin-4(1-39), [0158] des Pro36 [Met(O)14, Asp28] Exendin-4(1-39), [0159] des Pro36 [Met(O)14, IsoAsp28] Exendin-4(1-39), [0160] des Pro36 [Trp(O2)25, Asp28] Exendin-4(1-39), [0161] des Pro36 [Trp(O2)25, IsoAsp28] Exendin-4(1-39), [0162] des Pro36 [Met(O)14 Trp(O2)25, Asp28] Exendin-4(1-39), [0163] des Pro36 [Met(O)14 Trp(O2)25, IsoAsp28] Exendin-4(1-39), [0164] wherein the group -Lys6-NH2 may be bound to the C-terminus of the Exendin-4 derivative; [0165] or an Exendin-4 derivative of the sequence [0166] H-(Lys)6-des Pro36 [Asp28] Exendin-4(1-39)-Lys6-NH2, [0167] des Asp28 Pro36, Pro37, Pro38Exendin-4(1-39)-NH2, [0168] H-(Lys)6-des Pro36, Pro38 [Asp28] Exendin-4(1-39)-NH2, [0169] H-Asn-(Glu)5des Pro36, Pro37, Pro38 [Asp28] Exendin-4(1-39)-NH2, [0170] des Pro36, Pro37, Pro38 [Asp28] Exendin-4(1-39)-(Lys)6-NH2, [0171] H-(Lys)6-des Pro36, Pro37, Pro38 [Asp28] Exendin-4(1-39)-(Lys)6-NH2, [0172] H-Asn-(Glu)5-des Pro36, Pro37, Pro38 [Asp28] Exendin-4(1-39)-(Lys)6-NH2, [0173] H-(Lys)6-des Pro36 [Trp(O2)25, Asp28] Exendin-4(1-39)-Lys6-NH2, [0174] H-des Asp28 Pro36, Pro37, Pro38 [Trp(O2)25] Exendin-4(1-39)-NH2, [0175] H-(Lys)6-des Pro36, Pro37, Pro38 [Trp(O2)25, Asp28] Exendin-4(1-39)-NH2, [0176] H-Asn-(Glu)5-des Pro36, Pro37, Pro38 [Trp(O2)25, Asp28] Exendin-4(1-39)-NH2, [0177] des Pro36, Pro37, Pro38 [Trp(O2)25, Asp28] Exendin-4(1-39)-(Lys)6-NH2, [0178] H-(Lys)6-des Pro36, Pro37, Pro38 [Trp(O2)25, Asp28] Exendin-4(1-39)-(Lys)6-NH2, [0179] H-Asn-(Glu)5-des Pro36, Pro37, Pro38 [Trp(O2)25, Asp28] Exendin-4(1-39)-(Lys)6-NH2, [0180] H-(Lys)6-des Pro36 [Met(O)14, Asp28] Exendin-4(1-39)-Lys6-NH2, [0181] des Met(O)14 Asp28 Pro36, Pro37, Pro38 Exendin-4(1-39)-NH2, [0182] H-(Lys)6-desPro36, Pro37, Pro38 [Met(O)14, Asp28] Exendin-4(1-39)-NH2, [0183] H-Asn-(Glu)5-des Pro36, Pro37, Pro38 [Met(O)14, Asp28] Exendin-4(1-39)-NH2, [0184] des Pro36, Pro37, Pro38 [Met(O)14, Asp28] Exendin-4(1-39)-(Lys)6-NH2, [0185] H-(Lys)6-des Pro36, Pro37, Pro38 [Met(O)14, Asp28] Exendin-4(1-39)-(Lys)6-NH2, [0186] H-Asn-(Glu)5 des Pro36, Pro37, Pro38 [Met(O)14, Asp28] Exendin-4(1-39)-(Lys)6-NH2, [0187] H-Lys6-des Pro36 [Met(O)14, Trp(O2)25, Asp28] Exendin-4(1-39)-Lys6-NH2, [0188] H-des Asp28 Pro36, Pro37, Pro38 [Met(O)14, Trp(O2)25] Exendin-4(1-39)-NH2, [0189] H-(Lys)6-des Pro36, Pro37, Pro38 [Met(O)14, Asp28] Exendin-4(1-39)-NH2, [0190] H-Asn-(Glu)5-des Pro36, Pro37, Pro38 [Met(O)14, Trp(O2)25, Asp28] Exendin-4(1-39)-NH2, [0191] des Pro36, Pro37, Pro38 [Met(O)14, Trp(O2)25, Asp28] Exendin-4(1-39)-(Lys)6-NH2, [0192] H-(Lys)6-des Pro36, Pro37, Pro38 [Met(O)14, Trp(O2)25, Asp28] Exendin-4(S1-39)-(Lys)6-NH2, [0193] H-Asn-(Glu)5-des Pro36, Pro37, Pro38 [Met(O)14, Trp(O2)25, Asp28] Exendin-4(1-39)-(Lys)6-NH2; [0194] or a pharmaceutically acceptable salt or solvate of any one of the afore-mentioned Exedin-4 derivative. [0195] Hormones are for example hypophysis hormones or hypothalamus hormones or regulatory active peptides and their antagonists as listed in Rote Liste, ed. 2008, Chapter 50, such as Gonadotropine (Follitropin, Lutropin, Choriongonadotropin, Menotropin), Somatropine (Somatropin), Desmopressin, Terlipressin, Gonadorelin, Triptorelin, Leuprorelin, Buserelin, Nafarelin, Goserelin. [0196] A polysaccharide is for example a glucosaminoglycane, a hyaluronic acid, a heparin, a low molecular weight heparin or an ultra low molecular weight heparin or a derivative thereof, or a sulphated, e.g. a poly-sulphated form of the above-mentioned polysaccharides, and/or a pharmaceutically acceptable salt thereof. An example of a pharmaceutically acceptable salt of a poly-sulphated low molecular weight heparin is enoxaparin sodium. [0197] Antibodies are globular plasma proteins (˜150 kDa) that are also known as immunoglobulins which share a basic structure. As they have sugar chains added to amino acid residues, they are glycoproteins. The basic functional unit of each antibody is an immunoglobulin (Ig) monomer (containing only one Ig unit); secreted antibodies can also be dimeric with two Ig units as with IgA, tetrameric with four Ig units like teleost fish IgM, or pentameric with five Ig units, like mammalian IgM. [0198] The Ig monomer is a “Y”-shaped molecule that consists of four polypeptide chains; two identical heavy chains and two identical light chains connected by disulfide bonds between cysteine residues. Each heavy chain is about 440 amino acids long; each light chain is about 220 amino acids long. Heavy and light chains each contain intrachain disulfide bonds which stabilize their folding. Each chain is composed of structural domains called Ig domains. These domains contain about 70-110 amino acids and are classified into different categories (for example, variable or V, and constant or C) according to their size and function. They have a characteristic immunoglobulin fold in which two β sheets create a “sandwich” shape, held together by interactions between conserved cysteines and other charged amino acids. [0199] There are five types of mammalian Ig heavy chain denoted by α, δ, ε, γ, and μ. The type of heavy chain present defines the isotype of antibody; these chains are found in IgA, IgD, IgE, IgG, and IgM antibodies, respectively. [0200] Distinct heavy chains differ in size and composition; α and γ contain approximately 450 amino acids and δ approximately 500 amino acids, while μ and ε have approximately 550 amino acids. Each heavy chain has two regions, the constant region (CH) and the variable region (VH). In one species, the constant region is essentially identical in all antibodies of the same isotype, but differs in antibodies of different isotypes. Heavy chains γ, α and δ have a constant region composed of three tandem Ig domains, and a hinge region for added flexibility; heavy chains μ and ε have a constant region composed of four immunoglobulin domains. The variable region of the heavy chain differs in antibodies produced by different B cells, but is the same for all antibodies produced by a single B cell or B cell clone. The variable region of each heavy chain is approximately 110 amino acids long and is composed of a single Ig domain. [0201] In mammals, there are two types of immunoglobulin light chain denoted by λ and κ. A light chain has two successive domains: one constant domain (CL) and one variable domain (VL). The approximate length of a light chain is 211 to 217 amino acids. Each antibody contains two light chains that are always identical; only one type of light chain, κ or λ, is present per antibody in mammals. [0202] Although the general structure of all antibodies is very similar, the unique property of a given antibody is determined by the variable (V) regions, as detailed above. More specifically, variable loops, three each the light (VL) and three on the heavy (VH) chain, are responsible for binding to the antigen, i.e. for its antigen specificity. These loops are referred to as the Complementarity Determining Regions (CDRs). Because CDRs from both VH and VL domains contribute to the antigen-binding site, it is the combination of the heavy and the light chains, and not either alone, that determines the final antigen specificity. [0203] An “antibody fragment” contains at least one antigen binding fragment as defined above, and exhibits essentially the same function and specificity as the complete antibody of which the fragment is derived from. Limited proteolytic digestion with papain cleaves the Ig prototype into three fragments. Two identical amino terminal fragments, each containing one entire L chain and about half an H chain, are the antigen binding fragments (Fab). The third fragment, similar in size but containing the carboxyl terminal half of both heavy chains with their interchain disulfide bond, is the crystalizable fragment (Fc). The Fc contains carbohydrates, complement-binding, and FcR-binding sites. Limited pepsin digestion yields a single F(ab′)2 fragment containing both Fab pieces and the hinge region, including the H—H interchain disulfide bond. F(ab′)2 is divalent for antigen binding. The disulfide bond of F(ab′)2 may be cleaved in order to obtain Fab′. Moreover, the variable regions of the heavy and light chains can be fused together to form a single chain variable fragment (scFv). [0204] Pharmaceutically acceptable salts are for example acid addition salts and basic salts. Acid addition salts are e.g. HCl or HBr salts. Basic salts are e.g. salts having a cation selected from alkali or alkaline, e.g. Na+, or K+, or Ca2+, or an ammonium ion N+(R1)(R2)(R3)(R4), wherein R1 to R4 independently of each other mean: hydrogen, an optionally substituted C1 C6-alkyl group, an optionally substituted C2-C6-alkenyl group, an optionally substituted C6-C10-aryl group, or an optionally substituted C6-C10-heteroaryl group. Further examples of pharmaceutically acceptable salts are described in “Remington's Pharmaceutical Sciences” 17. ed. Alfonso R. Gennaro (Ed.), Mark Publishing Company, Easton, Pa., U.S.A., 1985 and in Encyclopedia of Pharmaceutical Technology. [0205] Pharmaceutically acceptable solvates are for example hydrates.

The present invention inter-alia relates to an apparatus comprising a needle guide configured to at last partially receive a needle of a needle assembly in a longitudinal opening and to center the needle of the needle assembly in the longitudinal opening, wherein the needle guide is longitudinally compressible.

RELATED APPLICATIONS This Application is a continuation of co-pending U.S. patent application Ser. No. 13/373,775 filed Nov. 30, 2011 now abandoned which is a continuation of U.S. patent application Ser. No. 12/499,584 filed Jul. 8, 2009 now abandoned. This Application claims rights under 35 USC §119(e) from U.S. Application Ser. No. 61/134,277 filed Jul. 8, 2008, the contents of which are incorporated herein by reference. FIELD OF THE INVENTION This invention relates to directed infrared countermeasures and more particularly to a non-adjustable pointer-tracker gimbal for use in such systems. BACKGROUND OF THE INVENTION In directed infrared countermeasures (DIRCM) systems there has always been a problem of making the line-of-sight (LOS) to the target and the laser beam that is emitted from the DIRCM head coincident or parallel. While there have been many efforts to reduce the amount of parallax between the two and therefore reduce the aiming errors of the outgoing laser beam, the difficulty in the past has always been with the multiple mirrors that are utilized both for positioning the received image at the center of a focal plane array and for directing the laser beam out the DIRCM head. In typical alignment procedures the multiple mirrors in the DIRCM head involve individual and independent adjustments. While it is possible for one pointing direction to adjust out the parallax by adjusting all the mirrors, the adjustment does not correct for all pointing directions. Since these mirrors move independently, the positional errors of the mirrors add up and are not easily compensated for over the entire field of regard. The situation is even further complicated as to how to lock the adjustment mechanisms without moving the adjustment while at the same time retaining boresight in view of the harsh environment. Thus, in a cut and try operation one can spend an inordinate amount of time trying to compensate for the positional errors of these mirrors for all pointing directions; but in general these efforts have not met with success. It is required that the angular error between the line-of-sight to the target and the laser path be extremely accurate and not exceed the laser divergence. There are a number of accumulated tolerances that must be compensated for i.e. mirror and support inaccuracies, focal plane array mounting inaccuracies, and gimbal fabrication tolerances. An objective in some DIRCM designs is to ensure that parallax allocation between the line-of-sight to the target and the laser beam path is less than 200 microradians, which is an exceedingly aggressive requirement. It is even more daunting because of the independent movement of the mirrors involved, noting that the angular errors accumulate for the various pointing directions. Moreover, compensating these mirrors for a single direction does not compensate the system for the entire field of regard. There is therefore a need for a simplified gimbaling system that assures that if one detects the target image that appropriate movement will occur to insure the laser will in fact illuminate the target with laser energy and not miss it. It would be noted that for gimbals the first step for the gimbal and the mirrors associated with it in a semi-spherical field of regard is to reflect the target image through a telescope and onto a focal plane array which is sensitive to the desired spectrum of light. The telescope not only focuses the target image but provides the means to measure angular displacement. Once the image is received on the focal plane array the displacement from the center is calculated and interpreted into angular displacement. This angular displacement is used to drive the azimuth and elevation stages of the gimbal, and associated mirrors, to drive the target image to the center of the focal plane array. Once the image is in the center of the focal plane array the laser is fired, with the assumption that the laser beam is parallel to the line-of-sight to the incoming image. This is where the problem arises. If there is error in parallax beyond the divergence of the laser beam the energy will not hit the target and the missile may not be jammed. In one particular DIRCM system the head housing the gimbal is stable and the camera is fixed to the head. The result is that all of the pointing is done with movable mirrors. Note that the mirrors in the past have been adjustable with respect to the housing to which the camera is fixedly attached. Once the target image reaches the camera, this target image is imaged onto a focal plane array so that the image is a particular spot within the field of view. The mirrors associated with acquiring the target image are physically moved so that the image spot is moved to the center of the focal plane array as described above. Once the mirrors have centered the image at the center of the focal plane array, the laser is fired such that the direction of the laser beam corresponding to the center point of the array goes out coincident with or parallel to the line-of-sight to the target. If there were no pointing errors, then the outgoing laser beam would be coincident with or parallel with the line-of-sight to the target, and the laser beam would hit the target. However, and as described above, it is difficult or impossible to post align the incoming image with the exiting laser beam after the gimbal has been assembled due the accumulation of errors throughout the assembly especially since a high degree of accuracy is required. This is where a simple and accurate system must be implemented to insure DIRCM functionality. SUMMARY OF THE INVENTION Rather than trying to adjust all of the mirrors and affiliated hardware in the DIRCM head or gimbal to compensate for all pointing errors, in the subject case the input and output mirrors are mounted to a rigid uni-construction elevation arm that is part of an elevation stage and are initially fabricated to reasonable tolerances. The subject system does not try to adjust the mirrors for every pointing direction, rather deals with the original unadjusted alignment of the mirrors and provides a system to compensate the aiming direction of the laser by adjusting the azimuth and elevation stages with an offset determined during an initial calibration procedure to bring the outgoing laser beam as close as possible to being parallel to the line-of-sight to the target. With this parallelism, the result is that the laser beam hits the target with maximal energy on target. The above offset adjustment is done by moving the elevation arm and an azimuth platter on which all of the apparatus is mounted in accordance with the errors determined in an initial calibration procedure. In one embodiment, manufacturing tolerances or errors are determined by a series of system calibration techniques. These error solutions are placed into a software look-up table which is referred to as an aim-point map. The intent is to drive the azimuth and elevation stages to position the target image at the center of the focal plane array taking into account the offset given by the look-up table. Once the target has been located on the gimbal's focal plane array, the image position or displacement relative to the center of the focal plane array is calculated. The image displacement is corrected by values from the aim-point map with the corrected displacement used to drive the gimbal's azimuth and elevation stages redirecting the laser beam to strike the target. As a result, the above process places the laser beam on target by shifting the laser beam to be as parallel as possible to the line-of-sight to the target. As used herein, line-of-sight refers to the line-of-sight to the target, not the line-of-sight of the gimbal. Since the mirrors and mechanical mechanisms are fixed in which no adjustments can be made, the laser beam and target image are shifted together so that after the elevation and azimuth stages are driven, the image is no longer in the center of the focal plane array and the electrical center of the focal plane array is shifted by this amount. In one embodiment, the initial calibration procedure involves rotating a DIRCM head on a rotary table with the gimbal's azimuth axis coincident with that of the rotary table. Thereafter a simulated target is mounted at far-field and an IR reflector is mounted behind the target. Then the system initiates a sequence to “track” to the target and fire the IR laser at a predetermined azimuth and elevation coordinate. As indicated above there are a number of factors involved in assessing accuracy requirements and these same factors determine calibration increments. In one embodiment, the DIRCM head is rotated in 5° increments, and measurements are taken of the offset between the target and the position of the reflected laser beam returned to the focal plane array at each increment. These offsets are then stored in an aim-point map look up table. In summary, in an initial alignment procedure the DIRCM head is rotated on a table with a target at a fixed location and a reflector behind the target, and an aim-point map records the error between the line-of-sight to the target and the position of the reflected beam for each pointing direction, with the offset corresponding to this error stored in an aim-point map lookup table accessed by pointing direction. In operation, once the DIRCM is calibrated, first a target is detected within the field-of-view of the camera and imaged onto the focal plane array. Then the displacement of the target image from the center of the focal plane array is calculated. If there were no tolerances and the mirrors were perfect as regards parallax, the azimuth and elevation stages would move the mirrors so the target image was exactly at the center of the focal plane array and lazing would commence with success. But, due to the above inaccuracies, the aim-point map value at the line-of-sight angle is added to the algorithms that determine how to move the azimuth and elevation stages to place the laser beam on the target Thus, using these aim-point map values, the azimuth and elevation stages are stimulated to correct the position of the output mirror to make the output beam parallel to the line-of-sight to the target and thus assure 200 or better microradian aiming accuracy. It is a feature of the subject invention that a single member is used to fixedly mount the image or input mirror and the laser or output mirror. This marries the two mirrors to one structural member such that both the input mirror and the output mirror move as one. This member in one embodiment is a uni-construction elevation arm which is rotated about the elevation axis. The elevation arm is in turn mounted to an azimuth platter which rotates the entire structure about the azimuth axis. The critical mirrors rather than being individually controlled are now rotated in unison by the elevation arm and the azimuth platter so that the mirrors are ganged together, and no attempt is made to adjust these mirrors independently as has been done in the past. Alignment errors for any pointing direction are compensated using the elevation and azimuth stages to move both the input and output mirrors in accordance with the calculated image displacement modified by the offset errors recorded in the aim-point map. This completely eliminates the problem of trying to independently adjust multiple moving mirrors to provide the precision necessary to accomplish the 200 microradian pointing accuracy for the laser beam. Thus the subject system compensates for manufacturing errors in a software look-up table and permits designing the mirrors and affiliated support mechanisms without adjustments. Additional simplicity is added when the first stage input mirror and the laser output mirror are designed and fabricated as a single part called a uni-construction elevation arm. Concurrent with the look-up table approach which eliminates or minimizes the effects of manufacturing tolerances, there is also the problem of temperature gradients. As hardware heats and expands or contracts, asymmetrical parts change shape which will affect overall performance, especially pointing accuracy. In the past hardware designers would try and design symmetrical hardware or select hardware with a common thermal expansion characteristic. However, most of these alternatives are costly and somewhat subjective. The subject system compensates for thermal gradients by firing the laser onto the focal plane array as a reference point and periodically re-firing the laser back onto the focal plane array at the same gimbal position, with any offset being measured and used to adjust the elevation and azimuth stages of the gimbal. This provides an additional calibration factor by providing a reference of how the aim-point of the gimbal changes with varying temperatures. This reference procedure is called boresight alignment and is done periodically to assure alignment. In summary, a system is provided to assure that the laser beam from a DIRCM head or gimbal places laser energy on the target without complicated adjustments, and expensive parts. This is accomplished by providing a uni-constructed elevation arm with both input and output mirrors fixed to it, and an aim-point map that compensates for all manufacturing tolerances to gain the end objective of jamming heat-seeking missiles. In operation, the position of the output mirror is moved in accordance with target image displacement corrected by the error recorded in the aim-point map to correct the angular orientation of the output mirror for assuring that the outgoing beam is parallel to the line-of-sight to the target. Thermal gradient problems are also compensated by using the sensed gradient-induced errors to adjust aim-point map values. BRIEF DESCRIPTION OF THE DRAWINGS These and other features of the subject invention will be better understood in connection with the Detailed Description, in conjunction with the Drawings, of which: FIG. 1 is a diagrammatic illustration of a directed infrared countermeasures pointer-tracker gimbal illustrating the line-of-sight to a threat such as an incoming missile and a laser beam which misses the missile due to parallax inaccuracy; in which the parallax must be adjusted out by adjusting the mirrors or by using other mechanisms; FIG. 2 is a diagrammatic illustration of a pointer-tracker gimbal in which all mirrors, the input mirror, internal mirrors and the output mirror are independently adjustable to compensate for errors between the image path or line-of-sight to the target, and the laser path of the outgoing laser beam to establish parallelism between the two paths, noting the number of potential items needing adjustment; FIG. 3 is a diagrammatic illustration of the subject system using unadjusted mirrors in which all mirrors are affixed to a rigid assembly comprising the elevation and azimuth stages of the gimbal, and in which an aim-point error map lookup table provides an offset through an offset generator for driving the elevation and azimuth stages of the gimbal which offsets the laser beam by the amount specified by the aim-point map to establish laser energy on target. FIG. 4 a is a diagrammatic illustration of the elements in the gimbal of FIG. 3 showing an elevation arm to which input mirror and output mirrors are fixedly attached, with the elevation arm carried on an azimuth platter to which the internal mirrors are fixedly attached, showing a target image displaced from the center of the focal plane array, also showing the parallax between the laser output beam and the line-of-sight to the target; FIG. 4 b is a diagrammatic illustration of the system of FIG. 4 a , showing applying aim-point map corrections which are then converted to drive coordinates that are in turn used to generate azimuth and elevation drive signals to move the output mirror to correct for parallax errors and place laser energy on target; FIG. 5 is a diagrammatic illustration of the fixing of the input mirror and the output mirror to a uni-construction elevation arm; FIG. 6 is a diagrammatic illustration of the elevation arm of FIG. 5 , illustrating the angular displacement between the line-of-sight to the target and the outgoing laser beam due to manufacturing tolerances in fabrication; FIG. 7 is a diagrammatic illustration of the mounting of the uni-construction elevation arm of FIG. 6 on an azimuth platter, in which the elevation and azimuth stages are utilized first to center the target image on the focal plane array in a gimbal camera and then to aim the output of a laser to be parallel with the line-of-sight to the target; FIG. 8 is a diagrammatic illustration of the movement of the elevation arm subsequent to the imaging of a target on the focal plane array of FIG. 1 in which the output mirror is moved by the elevation arm and the azimuth platter by the offset established by the aim-point map, such that the laser beam is made to exit parallel to the line-of-sight to the target; and, FIG. 9 is a diagrammatic schematic of the boresight alignment system including a retro-return prism. DETAILED DESCRIPTION Referring now to FIG. 1 , a pointer-tracker gimbal 10 is utilized to detect the line-of-sight 12 to a target 14 and aim a laser beam 16 towards the head of the missile. Pointing accuracies required for such pointer-trackers are substantial. The pointing accuracies required to assure a hit on the target must be less than the total errors within the system, namely in one embodiment a 200 microradian divergence between the line-of-sight to the target and the projected laser beam. As illustrated, the laser beam path 16 and the line-of-sight to the true target 14 must be brought into alignment as would be the case with a coincidence of the back projection of the laser 16 beam with target image 19 on focal plane array 17 . This is done by adjustments that must be maintained during the harsh environment of military aircraft. This stringent requirement in and of itself is extremely difficult to achieve and as shown in FIG. 2 , gimbals require individually adjustable mirrors, namely an input mirror 18 , a series of internal mirrors 20 and 24 , and an output mirror 26 and their affiliated mounting mechanisms. Included in the potential adjustments are laser 32 , telescope 28 and focal plane array 17 . The DIRCM head of FIG. 2 utilizes a camera 27 including telescope 28 and focal plane array 17 , along with laser 32 . The input path 34 , or line-of-sight to the target, is such that the image is redirected at the surface of input mirror 18 towards adjustable internal mirror 24 where it is redirected through telescope 28 onto focal plane array 17 . The gimbaling system moves the various mirrors to center the target image at the center of the focal plane array. When this has been achieved a laser beam 36 is redirected by a series of mirrors 38 and 39 so that the output of laser 32 is directed along the centerline 40 of the gimbal or the azimuth axis. Thereafter, the laser beam is projected along axis 40 and is redirected by adjustable internal mirror 20 towards output mirror 26 where it is redirected along laser path 28 . Note the parallelism of the input path and the laser path are determined by the precise positions of all of the mirrors and mechanical supports involved. Some pointer-tracker gimbals independently adjust some or all of the mirrors to establish this parallelism. As mentioned previously, the adjustment required also includes adjustment of the laser, the camera and any other support mechanisms that influence beam parallelism. It will be appreciated that the adjustment of mirrors to establish parallelism is a daunting task. The result is that it is only with difficulty that one can adjust the mirrors to make sure that the laser path is parallel with the image path line-of-sight to the target. More often than not there is an excessive angular error between the line-of-sight input path and the actual direction of the output laser beam as illustrated by dotted lines 44 and 45 . As mentioned hereinabove, there is a requirement to provide a much more simple system in order to assure that the laser beam projected out from dome 46 of the gimbal be properly aligned with the line-of-sight to the target, especially to a less than 200 microradian error. It is also noted that cross coupling errors between the various moving mirrors in the system shown in FIG. 2 are cumulative, which in part explains the difficulty in establishing the parallelism required. As illustrated in FIG. 3 and as will be described, gimbal 10 is provided with mirrors that are fixed with no adjustments possible. Rather than trying to adjust each of the individual mirrors to eliminate aiming errors, in the subject system the azimuth and elevation stages are moved to reposition the output mirror by an offset determined by a calibration procedure that results in the generation of an aim-point map 50 . Using this map, an offset generator 52 repositions the azimuth and elevation stages of the gimbal to offset the position of the output mirror to place laser energy on target. As can be seen the position of the laser beam back projected on focal plane array is initially set up to be at the center of the focal plane array. Once acquired, the target image is displaced from the center of the focal plane array by an X and Y offset. To get the laser beam to hit the target, the X and Y offsets are used to move the azimuth and elevation drives. However, due to the tolerance problems mentioned above the X and Y offsets are modified by the calibration values from the aim-point map. The calibration procedure requires taking the gimbal and mounting it to a rotating table. In one embodiment, the table is rotated every 5° and tracks a fixed target. The laser is fired against a reflective background and the laser image is recorded on the focal plane array. This produces two images on the focal plane array, one the target and the other the laser energy. The X/Y offset is recorded in the aim-point map 50 relative to a specific gimbal angle, and the calibration process is repeated every 5° or to whatever resolution needed. Thus, the gimbal is rotated in increments to establish the corresponding errors for all of the lines of sight within the field of view of the gimbal. Therefore, what is established are measured angle-dependant aiming errors. The corresponding offsets for the output mirror are then generated by offset generator 52 for a detected line-of-sight to the target. In operation, first a target is acquired utilizing an on-board missile acquisition warning system in which fixed cameras located around the periphery of the aircraft look out over a certain field of regard. When a target appears within the field of regard, the coordinates of the target are calculated from the missile acquisition warning system and Euler's equation is used to transpose the coordinates of the target into platform coordinates. Once this has been accomplished, gimbal 10 is slewed over so as to position the target image in the field of view of camera 69 which is used as the “fine track sensor” within gimbal 10 . Having located the target image on the focal plane array of camera 69 , the subject system measures the distance from the center of the focal plane array to the target image point. This is done by measuring the displacement of the image from the center of the focal plane array 72 in the X and Y directions. Note that when one measures the X and Y coordinates of the image displacement, one is no longer dealing with the world coordinates or platform coordinates, but rather simply coordinates related to the focal plane array. Once the displacement from the center of the focal plane array is ascertained, the aim-point map look up table (LUT) 50 is accessed to correct or modify the X and Y coordinates of the image based on the previously established aim-point map errors. These modified X and Y coordinates are then used to stimulate the gimbal motors to move the azimuth and elevation stages, and this is done taking into account the offsets recorded in the aim-point map. This places laser energy on the target by reducing as close to zero the parallax error between the image and laser paths. Note that the modified X and Y displacements used in this process do not directly relate to motor drive coordinates. Rather, they are rotated with an end point rotation algorithm that is applied when one drives the two motors in the azimuth and elevation directions to the end point established by the measured displacement and aim-point map error correction. Thus for any particular target one looks to the aim-point map to readjust the true aim-point. In short, the system measures the X and Y displacements from the center of the aim-point map to where the actual image is located on the focal plane array, with these measurements being corrected for the errors from the aim-point map. Noting that both the elevation arm and the azimuth plate have their own drive motors, it is the purpose of the subject invention to stimulate azimuth and elevation drives to reduce the parallax errors. In one embodiment, there is constant updating commensurate with the frame rate of the camera. Thus, if the aircraft has moved, with the elevation and azimuth drive motors being hefty enough, one can track the rapid target or aircraft movement. It is well to remember that just positioning the target image at the center of the focal plane array does not necessarily point the laser beam to the appropriate point in space due to the tolerances involved in the laser pointing process. Thus to compensate for the errors for a particular angle of arrival one looks up the aim-point map and readjusts. In short, one can measure the X and Y displacements on the focal plane array between the image and the laser beam and use the values of the aim-point map look-up table to correct these measured displacements. FIG. 4 a depicts the hardware set illustrating the two paths: line-of-sight 62 or the image path to the target and laser path 92 . The error in parallelism present between the two paths is labeled “parallax error”. Here it can be seen that a non-adjustable input or image mirror 60 redirects the image coming in along line-of-sight 62 to non-adjustable mirrors 64 and 65 , one of which redirects the image through an aperture 66 in an azimuth platter 68 and into a telescope 70 and onto a focal plane array 72 . The telescope and focal plane array are part of camera 69 . Laser 74 has its beam redirected by mirrors 76 and 78 up through aperture 66 where it is redirected by internal mirror 65 onto the reflective surface of output mirror 80 . In the subject invention input mirror 60 and the output mirror 80 are fixedly attached to a rigid elevation arm 82 which rotates about the elevation axis. It is also noted that the elevation arm is mounted on azimuth platter 68 , whereas internal mirrors 64 and 65 are fixedly attached to the azimuth platter as well, but not attached to the elevation arm. It will thus be appreciated that mirrors 60 , 64 , 65 and 80 are non-adjustable and fixedly attached to their supports. Here, input mirror 60 and output mirror 80 are moved with the rotation of the elevation arm. Note that all the mirrors are moved with the rotation of the azimuth platter. Thus, the elevation arm as well as internal mirrors 64 and 65 attached to azimuth platter 68 are rotated with the azimuth platter coupled. As shown in FIG. 4 b , target 14 is acquired from data supplied from the missile warning system. The gimbal 10 slews to the target location and an image of the target is acquired by camera 69 and focal plane array 72 . At this point camera 69 starts to position the gimbal from data collected from the focal plane array. The uncorrected x, y target image coordinates of point 120 result in a displacement measured from the center of the focal plane array. This measurement as illustrated at 124 is added at 126 to the values from aim-point map 50 such that the uncorrected X and Y displacement is corrected and converted to drive coordinates at 128 . These drive coordinates are coupled to an azimuth and elevation drive 130 that are then coupled to an azimuth drive 86 and an elevation drive 84 to reposition the output mirror 80 to provide correction 90 to beam 92 . This establishes adjusted beam 92 ′ to be parallel to line-of-sight 62 . Since the repositioning of the output mirror also repositions the input mirror, a corrected line-of-sight 62 ′ is established. This in turn moves the target image on the focal plane array to the final target image location 120 ′. With the repositioning of the output mirror, the laser is now firing at the target with great accuracy. As shown in FIG. 4 b , in order to rectify this situation, offset generator 52 is used to adjust both the elevation arm and the azimuth platter in accordance with measured X and Y displacements of the target image modified by the aim-point map values associated with the particular line-of-sight involved. This causes the output and input mirrors to be repositioned as shown by dotted lines 80 ′ and 60 ′, such that rather than directing the laser beam 92 in the direction shown which is not where the target is, laser beam 92 is reflected by the moved output mirror 80 ′ to now lie along beam path 92 ′ parallel to line-of-sight 62 . This places the laser energy on the target. In moving output mirror into position 80 ′ the input or image mirror is also moved displacing the image from the center of the focal plane array to its final position as shown at 120 ′. As will be appreciated, when a target image comes in on a detected line-of-sight, the aim-point map lookup table is accessed by angle and outputs the appropriate error values to offset generator 52 that stimulates the elevation arm drive and the azimuth platter drive to adjust the position of the mirrors. Thus, the measured errors from the initial alignment are used to reposition the output and input mirrors. This eliminates the necessity of trying to adjust mirrors, or in fact trying to compensate on the fly for positional errors for all of the mirrors. In the subject invention, after manufacture, the positions of the mirrors are non-adjustable and compensation for pointing errors is under the control of the aim-point map generated in the calibration process. As to the construction of the uni-construction elevation arm, referring to FIG. 5 , elevation arm 82 is shown with input mirror 60 and output mirror 80 fixedly attached. The arm is carried on trunnions 94 and 96 for rotation about an elevation axis 98 , in which the trunnions are fixedly attached to azimuth platter 68 which rotates about an azimuth axis 100 . Note that platter 68 is provided with a central aperture 102 through which the incoming path from the target passes and out of which the laser beam projects. As noted hereinafter, the camera including the telescope and focal plane array, as well as the laser are housed in gimbal housing 104 . Referring now to FIG. 6 , elevation arm 82 is shown in detail with input mirror 60 and output mirror 80 shown reflecting the target image that comes in over line-of-sight 62 . If the mirrors are perfectly orthogonal to each other the angular displacement would be zero for the elevation arm only. However, creating a perfect elevation arm does not compensate for the remaining tolerances within the system. Here, the outgoing laser beam is reflected by output mirror 80 and is directed along a path 92 . However, due to alignment errors and tolerances, there is an angular displacement 110 between the line-of-sight direction 62 and the direction 92 of the outgoing beam as shown by error 113 . Here it can be seen that uni-construction elevation arm 82 has a U-shaped portion 112 having legs 114 and 116 to which mirrors 60 and 80 are respectively attached. The elevation arm drive includes a motor 119 which is located on a disk 121 fixedly attached to arm 116 of elevation arm 82 . Referring now to FIG. 7 in which like elements have like reference characters, what can be seen is that the uni-construction elevation arm 82 fixedly carries input mirror 60 and output mirror 80 and is mounted for rotation about elevation axis 98 . Here the internal mirrors 64 are shown mounted to an assembly 140 fixedly mounted to azimuth platter 68 . As illustrated, camera 69 shown in dotted outline includes the aforementioned telescope and focal plane array, whereas the laser 74 is shown in dotted outline, all within gimbal housing 104 . Referring now to FIG. 8 , an original position of the elevation arm 82 is shown in which line-of-sight 62 and the resulting outgoing laser beam 92 are angularly displaced as illustrated by angular displacement 110 . It is the purpose of the subject invention to be able to reposition output mirror 80 to cancel out any non-parallelity between these two beams to keep the angular alignment error within 200 microradians. In accordance with the offset 90 for the elevation stage, output mirror 80 is adjusted in the direction of arrow 130 utilizing elevation drive 84 , driven in accordance with the offset from aim-point error map 50 so that the angular position of mirror 80 is changed to the indicated by dotted line 80 ′. Likewise, laser beam 92 is shifted by the repositioning of the output mirror 80 into its aligned position at 92 ′. As can be seen, the entire elevation arm is rotated either by the elevation drive or the azimuth platter drive, or both, such that it is altered in position as illustrated by the dotted outlines shown. The result is that with an angle of arrival established for the target image, the aim-point map is used to provide offsets to the elevation and azimuth drives to adjust the output mirror in accordance with the previously determined offset for the particular gimbal involved. As to the boresighting subsystem and referring to FIG. 9 , at initial aim-point map calibration a reference boresight point is taken establishing the reference point with which to compare other periodic firings. At a pre-determined period the boresight is checked and the offset recorded. If there is a change to the boresight value this indicates a change to the aim-point and that value is added onto the aim-point map value as illustrated in FIG. 4 b at βx and βy. FIG. 9 illustrates the mechanism that allows the laser to fire back into the gimbal and strike the focal plane array. The elevation arm 82 is positioned below the field of regard using a hard stop to maintain consistency. This points the input mirror 60 and the output mirror down toward a retro-return prism 134 . The azimuth is driven to three determined spots and the laser is fired at each spot. As illustrated, the laser beam 16 strikes the output mirror 80 which is aimed at retro-return prism 134 . The laser beam passes through the prism as illustrated by arrow 135 and exits pointing towards the input mirror 60 as illustrated by arrow 137 . The reflective surface of input mirror directs the laser beam back into the gimbal via a fixed turning mirror as illustrated by arrows 141 and 142 down to focal plane array 72 . In one embodiment, the original calibration boresight image 138 on the focal plane array 72 was taken at the same time the aim-point map was generated. If there were no thermal gradients, each time a subsequent boresight alignment is attempted the laser beam would come back to the same point on the focal plane array. However, in the face of thermal gradients the returned laser beam is offset on the focal plane array by an offset 136 . This offset is recorded and as illustrated in FIG. 4 b , the boresight corrections βx and βy are added to the aim-point values to compensate for temperature gradients. Note that the boresight alignment may be periodically commenced before an engagement. An appendix is provided which describes the source code used in the subject invention. It will be appreciated that the drive for the two axis gimbal described herein is available commercially off-the-shelf from a variety of different vendors. While the present invention has been described in connection with the preferred embodiments of the various figures, it is to be understood that other similar embodiments may be used or modifications or additions may be made to the described embodiment for performing the same function of the present invention without deviating therefrom. Therefore, the present invention should not be limited to any single embodiment, but rather construed in breadth and scope in accordance with the recitation of the appended claims. APPENDIX /********************************************************************** ******** // FUNCTION: Aim-Point_Map_correction // // PURPOSE: The purpose of this function is to perform boresight correction // on the polar coordinate inputs using the aim-point map data. // // // // // // // // // NOTES: Boresight values will be set to zero until the target is // centered within a 32x32 window. Then first time, values will // be limited, after that boresight table values will be used. // *********************************************************************** ******/ struct cmd_az_el Boresight_correction(float TgtInterceptAz, float TgtInterceptEl) {   float azoffset, eloffset, Sumaz_el;   float finalValueaz, finalValueel, TargetAz, TargetEl;   struct cmd_az_el AIMPT, APOINT;   /* Convert from radians to degrees */   TargetAz = TgtInterceptAz * RAD2DEG;   TargetEl = TgtInterceptEl * RAD2DEG;   /* Determine the 2 closest index points in the boresight table, one   greater and one smaller than the point. Do for az and el */   /* Point 0 */   POINTS[0].az = (int) ((TargetAz/5) + 36); /* 180/5 = 36 */   POINTS[0].el = (int) ((TargetEl/5) + 6); /* 30/5 = 6 */   /* Point 1 */   POINTS[1].az = POINTS[0].az +1;   POINTS[1].el = POINTS[0].el;   /* Point 2 */   POINTS[2].az = POINTS[0].az;   POINTS[2].el = POINTS[0].el +1;   /* Correct for those points on the table edge */   if (POINTS[0].az = = 72) {    POINTS[1].az = 72;   }   else if (POINTS[0].az = = 0) {    POINTS[1].az = 0;   }   if (POINTS[0].el = = 0) {    POINTS[2].el = 0;   }   else if (POINTS[0].el = = 24) {    POINTS[2].el = 24;   }   /* Point 3 */   POINTS[3].az = POINTS[1].az;   POINTS[3].el = POINTS[2].el;   /* Determine the intercept percentage az and el offset from point one. First convert POINT[x].az index to degrees, az table index 2 is −170 degrees*/     azoffset = (TargetAz − (POINTS[0].az * 5 − 180))/5;     eloffset = (TargetEl − (POINTS[0].el * 5 − 30))/5;     finalValueaz = ((1-azoffset) * (1-eloffset) *     BORESIGHT_TBL.tbl[POINTS[0].el][POINTS[0].az].az) +     (azoffset * (1-eloffset) *     BORESIGHT_TBL.tbl[POINTS[1].el][POINTS[1].az].az) +     (azoffset * eloffset *     BORESIGHT_TBL.tbl[POINTS[3].el][POINTS[3].az].az) +     ((1-azoffset) * eloffset *     BORESIGHT_TBL.tbl[POINTS[2].el][POINTS[2].az].az);   finalValueel = ((1-azoffset) * (1-eloffset) *     BORESIGHT_TBL.tbl[POINTS[0].el][POINTS[0].az].e1) +     (azoffset * (1-eloffset)     BORESIGHT_TBL.tbl[POINTS[1].el][POINTS[1].az].e1) +     (azoffset * eloffset *     BORESIGHT_TBL.tbl[POINTS[3].el][POINTS[3].az].e1) +     ((1-azoffset) * eloffset *     BORESIGHT_TBL.tbl[POINTS[2].el][POINTS[2].az].e1);   /* Sum the angles in radians */   Sumaz_el = TgtInterceptAz + TgtInterceptEl;   /* Calculate offset aimpoint */   AIMPT.az = finalValueaz + AUTO_DIFS.gimbaltube.X +    (AUTO_DIFS.mirror.X * cos(Sumaz_el)) +     (AUTO_DIFS.mirror.Y * sin(Sumaz_el));   AIMPT.el = finalValueel + AUTO_DIFS.gimbaltube.Y +    (AUTO_DIFS.mirror.Y * cos(Sumaz_el)) −     (AUTO_DIFS.mirror.X * sin(Sumaz_el));    /* Zero boresight values until target is centered in 32x32 window */    if (!LaserOffsetMode) {     APOINT.az = 0.0;     APOINT.el = 0.0;    }    /* when switching to laser offset, limit max offset on first usage */    else {     if (LimitFlag) {      if (fabs(AIMPT.az) > PIXELOFFSETLIMIT) {       AIMPT.az *+ divider;      }      if (fabs(AIMPT.el) > PIXELOFFSETLIMIT) {       AIMPT.el *= divider;      }      divider += 0.1;      if (divider > 1.0) {       LimitFlag = FALSE;      }     }     /* Convert pixel aimpoint to radians */     APOINT.az = PIXEL2RAD * AIMPT.az;     APOINT.el = PIXEL2RAD * AIMPT.el;    }    return (APOINT); } *********************************************************************** ******* // FUNCTION: Autoboresight_processing // // PURPOSE:  The purpose of this function is to handle autoboresight // processing for four angles. This is done after each boresight // position commanded by the IPC and at pbit and cbit. // // NOTES: // *********************************************************************** ******/ void Autoboresight_processing (void) {   int sindex, Bad_value_flag = FALSE;   float autoAzvalue, autoElvalue, rota;   double eltotal=0, aztotal = 0, totAZpts=0, totELpts=0, aveAZpts=O,  aveELpts=0;   double totSQazpts=0, totSQelpts=0;   double newaz, newel;   unsigned char err;   * It has taken too long to collect autoboresight data, timeout is 3secs*/   if (End_autoboresight_timeout = =0)   {    Bad_value_flag = TRUE;    printf(“aE ”);   }   else   {    /* if (target is centered in 100x100 pixels) {*/    if (fabs(TRACK_PROCESSOR_RPT.target1_boresight_X) <= 128.0 &&     fabs(TRACK_PROCESSOR_RPT.target1_boresight_Y) <= 128.0)    {      /* Target is centered in both az and el, save the values */      tgt_pos[auto_sample_index].az =       TRACK_PROCESSOR_RPT.target1_boresight_X;      tgt_pos[auto_sample_index].el =       TRACK_PROCESSOR_RPT.target1_boresight_Y;       auto_sample_index++;       /* Are NUMOFTPSAMPLES collected */       if (auto_sample_index > (NUMOFTPSAMPLES))       {        /* else get autoboresight values for current angle */        autoAzvalue = AUTO_ANGLES.angle[current_angle].az;        autoElvalue = AUTO_ANGLES.angle[current_angle].el;        /*Determine how much each sample varies from         autoboresight values */        for (sindex=1; sindex < NUMOFTPSAMPLES+1; sindex++)        {          aztotal += tgt_pos[sindex].az − autoAzvalue;          eltotal += tgt_pos[sindex].el − autoElvalue;        }        /* Store average variation over the NUMOFTPSAMPLES     samples */        averageAz[current_angle] = aztotal / NUMOFTPSAMPLES;        averageEl[current_angle] = eltotal / NUMOFTPSAMPLES;        /* Calculate standard deviation - UPDATE −        get average */        for (sindex=1; sindex < NUMOFTPSAMPLES+1; sindex++)        {          totAZpts += tgt_pos[sindex].az;          totELpts += tgt_pos[sindex].el;        }        aveAZpts = totAZpts / NUMOFTPSAMPLES;        aveELpts = totELpts / NUMOFTPSAMPLES;        eltotal = 0;        aztotal = 0;        for (sindex=1; sindex < NUMOFTPSAMPLES+1; sindex++)        {         aztotal += pow((tgt_pos[sindex].az − aveAZpts), 2);         eltotal += pow((tgt_pos[sindex].el − aveELpts), 2);        }        if (sqrt(aztotal/(NUMOFTPSAMPLES −1)) > 0.250 | |         sqrt(eltotal/(NUMOFTPSAMPLES −1)) < 0.250)        {          err = 88;    /* exceeded standard deviation */          send_Health_IPC(err);        }        totAZpts = 0.0;        totELpts = 0.0;        totSQazpts = 0.0;        totSQelpts = 0.0;        /* Calculate standard deviation - UPDATE −        get average */        for (sindex=1; sindex < NUMOFTPSAMPLES+1; sindex++)        {         totAZpts += tgt_pos[sindex].az;         totELpts += tgt_pos[sindex].el;         totSQazpts += pow(tgt_pos[sindex].az 2);         totSQelpts += pow(tgt_pos[sindex].el 2);        {        newaz = pow(totAZpts,2) / NUMOFTPSAMPLES;        newel = pow(totELpts,2) / NUMOFTPSAMPLES;        if (((sqrt(totSQazpts - newaz) /         sqrt(NUMOFTPSAMPLES −1)) > 0.250) | |         ((sqrt(totSQelpts - newel)         sqrt(NUMOFTPSAMPLES −1)) > 0.250))        {         err = 88;     /* exceeded standard deviation */         send_Health_IPC(err);        }       } /* if auto_sample_index <= (NUMOFTPSAMPLES −1) */       /* Haven't collected all samples yet */       else       {        return;       }      }/* if centered */      else /* Can't collect samples until centered */      {       return;      }     } /* End_autoboresight timer = 0 */     /* Stop collecting because finished or wait until ready for next angle */     process_outgoing_LI_messages(STOP_BORE);     Autoboresight_collect = FALSE;     TPstate = STNDBY;     process_outgoing_TP_messages(AUTOTRACK, DISARM);      /* Finished processing for current angle, increment to next angle */     current_angle++;     /* Are there more angles to process */     if (current_angle < 4)     {      if (Autoboresight_in_progress)      {       AutoWaittimer = 44; /* 11 seconds delay */       End_autoboresight_timeout = 0; /* reset to zero */       auto_sample_index =0;      }     }     /* All 4 angles been processed */     else     {      /*threat_processing(HOME, 0);*/      Autoboresight_timeout = 0;      End_autoboresight_timeout = 0; /* reset to zero */      /* auto frame position and integ */      process_outgoing_TP_messages (9, 5);      Autoboresight_in_progress = FALSE;      if (Bad_value_flag)      {       send_Alert_IPC(BAD_AUTOBORESIGHT_DATA);      }      else      {       eltotal = 0;       aztotal = 0;       /* Calculate autoboresight correction attributable to tube */       AUTO_UPDATE.tube_values.az = (averageAz[angle1] +         averageAz[angle2] +        averageAz[angle3] + averageAz[angle4])/4;       AUTO_UPDATE.tube_values.el = (averageEl[angle1] +         averageEl[angle2] +        averageEl[angle3] + averageEl[angle4])/4;;       /* Calculate standard deviation for Azimuth */       if (sqrt((        pow((averageAz[angle1] − AUTO_UPDATE.tube_values.az), 2) +        pow((averageAz[angle2] − AUTO_UPDATE.tube_values.az), 2) +        pow((averageAz[angle3] − AUTO_UPDATE.tube_values.az), 2) +        pow((averageAz[angle4] − AUTO_UPDATE.tube_values.az), 2))/4)        > 0.250)       {         err = 88; /* exceeded standard deviation */         send_Health_IPC(err);       }       /* Calculate standard deviation for Elevation */       else if (sqrt((        pow((averageEl[angle1] − AUTO_UPDATE.tube_values.el), 2) +        pow((averageEl[angle2] − AUTO_UPDATE.tube_values.el), 2) +        pow((averageEl[angle3] − AUTO_UPDATE.tube_values.el), 2) +        pow((averageEl[angle4] − AUTO_UPDATE.tube_values.el), 2))/4)        > 0.250)       {         err = 88; /* exceeded standard deviation */         send_Health_IPC(err);       }        /* Calculate autoboresight correction attributable to mirrors */       aztotal = ((averageAz[angle1] − AUTO_UPDATE.tube_values.az) −        (averageAz[angle3] − AUTO_UPDATE.tube_values.az) −        (averageEl[angle2] − AUTO_UPDATE.tube_values.el) +        (averageEl[angle4] − AUTO_UPDATE.tube_values.el))/4;       eltotal = ((averageEl[angle1] − AUTO_UPDATE.tube_values.el) −        (averageEl[angle3] − AUTO_UPDATE.tube_values.el) −        (averageAz[angle2] − AUTO_UPDATE.tube_values.az) +        (averageAz[angle4] − AUTO_UPDATE.tube_values.az))/4;       rota = (Auto_Starting_Az + Auto_Starting_El) * DEG2RAD;       AUTO_UPDATE.mirror_values.az =        (aztotal * cos(-rota)) * cos(−rota)) + (eltotal * sin(−rota));       AUTO_UPDATE.mirror_values.el =        (eltotal * cos(−rota)) − (aztotal * sin(−rota));       threat_processing(AUTO_UP, 0);       send_Autoboresight_Update_IPC( );     }   } }

In a directed infrared countermeasure system, to assure parallelism between the line-of-sight to a target and the output beam, the input and output mirrors are fixedly attached to a uni-construction arm mounted to a rotatable azimuth platter to which internal mirrors are also fixedly attached. A system is provided for zeroing out alignment errors by developing an aim-point map for the gimbal that records initial alignment errors induced by manufacturing tolerances and uses the aim-point map error values to correct the output mirror orientation. The system also corrects for alignment errors induced by thermal gradients.

This application is a continuation of U.S. patent application Ser. No. 11/865,685, filed on Oct. 1, 2007, which is currently allowed, and is a continuation of U.S. patent application Ser. No. 10/187,132, filed on Jun. 28, 2002, (now U.S. Pat. No. 7,277,413) and which claims priority from: [1] U.S. Provisional Application Ser. No. 60/302,661, filed Jul. 5, 2001, entitled “HCF ACCESS THROUGH TIERED CONTENTION,” [2] U.S. Provisional Application Ser. No. 60/304,122, filed Jul. 11, 2001, entitled “HCF ACCESS THROUGH TIERED CONTENTION,” and [3] U.S. Provisional Application Ser. No. 60/317,933 filed Sep. 10, 2001, entitled “HCF ACCESS AND OVERLAPPED BSS MITIGATION,” all of which are incorporated herein by reference. RELATED APPLICATIONS This patent application is related to the regular U.S. patent application Ser. No. 09/985,257, filed Nov. 2, 2001, by Mathilde Benveniste, entitled “TIERED CONTENTION MULTIPLE ACCESS (TCMA): A METHOD FOR PRIORITY-BASED SHARED CHANNEL ACCESS,” (now U.S. Pat. No. 7,095,754) which is incorporated by reference. FIELD OF THE INVENTION The invention disclosed broadly relates to telecommunications methods and more particularly relates to Quality of Service (QoS) management in multiple access packet networks. BACKGROUND OF THE INVENTION Wireless Local Area Networks (WLANS) Wireless local area networks (WLANs) generally operate at peak speeds of between 10 to 100 Mbps and have a typical range of 100 meters. Single cell Wireless LANs, are suitable for small single-floor offices or stores. A station in a wireless LAN can be a personal computer, a bar code scanner, or other mobile or stationary device that uses a wireless network interface card (NIC) to make the connection over the RF link to other stations in the network. The single-cell wireless LAN provides connectivity within radio range between wireless stations. An access point allows connections via the backbone network, to wired network-based resources, such as servers. A single cell wireless LAN can typically support up to 25 users and still keep network access delays at an acceptable level. Multiple cell wireless LANs provide greater range than does a single cell, by means of a set of access points and a wired network backbone to interconnect a plurality of single cell LANs. Multiple cell wireless LANs can cover larger multiple-floor buildings. A mobile laptop computer or data collector with a wireless network interface card (NIC) can roam within the coverage area while maintaining a live connection to the backbone network. Wireless LAN specifications and standards include the IEEE 802.11 Wireless LAN Standard and the HIPERLAN Type 1 and Type 2 Standards. The IEEE 802.11 Wireless LAN Standard is published in three parts as IEEE 802.11-1999 ; IEEE 802.11 a -1999; and IEEE 802.11b-1999, which are available from the IEEE, Inc. web site http://grouper.ieee.org/groups/802/11. An overview of the HIPERLAN Type 1 principles of operation is provided in the publication HIPERLAN Type 1 Standard , ETSI ETS 300 652, WA2 Dec. 1997. An overview of the HIPERLAN Type 2 principles of operation is provided in the Broadband Radio Access Networks (BRAN), HIPERLAN Type 2 ; System Overview , ETSI TR 101 683 VI.I.1 (2000-02) and a more detailed specification of its network architecture is described in HIPERLAN Type 2 , Data Link Control ( DLC ) Layer; Part 4 . Extension for Home Environment , ETSI TS 101 761-4 V1.2.1 (2000-12). A subset of wireless LANs is Wireless Personal Area Networks (PANs), of which the Bluetooth Standard is the best known. The Bluetooth Special Interest Group, Specification Of The Bluetooth System , Version 1.1, Feb. 22, 2001, describes the principles of Bluetooth device operation and communication protocols. The IEEE 802.11 Wireless LAN Standard defines at least two different physical (PHY) specifications and one common medium access control (MAC) specification. The IEEE 802.11(a) Standard is designed to operate in unlicensed portions of the radio spectrum, usually either in the 2.4 GHz Industrial, Scientific, and Medical (ISM) band or the 5 GHz Unlicensed-National Information Infrastructure (U-NII) band. It uses orthogonal frequency division multiplexing (OFDM) to deliver up to 54 Mbps data rates. The IEEE 802.11(b) Standard is designed for the 2.4 GHz ISM band and uses direct sequence spread spectrum (DSSS) to deliver up to 11 Mbps data rates. The IEEE 802.11 Wireless LAN Standard describes two major components, the mobile station and the fixed access point (AP). IEEE 802.11 networks can also have an independent configuration where the mobile stations communicate directly with one another, without support from a fixed access point. A single cell wireless LAN using the IEEE 802.11 Wireless LAN Standard is an Independent Basic Service Set (IBSS) network. An IBSS has an optional backbone network and consists of at least two wireless stations. A multiple cell wireless LAN using the IEEE 802.11 Wireless LAN Standard is an Extended Service Set (ESS) network. An ESS satisfies the needs of large coverage networks of arbitrary size and complexity. Each wireless station and access point in an IEEE 802.11 wireless LAN implements the MAC layer service, which provides the capability for wireless stations to exchange MAC frames. The MAC frame transmits management, control, or data between wireless stations and access points. After a station forms the applicable MAC frame, the frame's bits are passed to the Physical Layer for transmission. Before transmitting a frame, the MAC layer must first gain access to the network. Three interframe space (IFS) intervals defer an IEEE 802.11 station's access to the medium and provide various levels of priority. Each interval defines the duration between the end of the last symbol of the previous frame, to the beginning of the first symbol of the next frame. The Short Interframe Space (SIPS) provides the highest priority level by allowing some frames to access the medium before others, such as an Acknowledgement (ACK) frame, a Clear to Send (CTS) frame, or a subsequent fragment burst of a previous data frame. These frames require expedited access to the network to minimize frame retransmissions. The Priority Interframe Space (PIFS) is used for high priority access to the medium during the contention-free period. The point coordinator in the access point connected to backbone network, controls the priority-based Point Coordination Function (PCF) to dictate which stations in cell can gain access to the medium. The point coordinator in the access point sends a contention-free poll frame to a station, granting the station permission to transmit a single frame to any destination. All other stations in the cell can only transmit during contention-free period if the point coordinator grants them access to the medium. The end of the contention-free period is signaled by the contention-free end frame sent by the point coordinator, which occurs when time expires or when the point coordinator has no further frames to transmit and no stations to poll. The distributed coordination function (DCF) Interframe Space (DIFS) is used for transmitting low priority data frames during the contention-based period. The DIFS spacing delays the transmission of lower priority frames to occur later than the priority-based transmission frames. An Extended Interframe Space (EIFS) goes beyond the time of a DIFS interval, as a waiting period when a bad reception occurs. The EIFS interval provides enough time for the receiving station to send an acknowledgment (ACK) frame. During the contention-based period, the distributed coordination function (DCF) uses the Carrier-Sense Multiple Access With Collision Avoidance (CSMA/CA) contention-based protocol, which is similar to IEEE 802.3 Ethernet. The CSMA/CA protocol minimizes the chance of collisions between stations sharing the medium, by waiting a random backoff interval, if the station's sensing mechanism indicates a busy medium. The period of time immediately following traffic on the medium is when the highest probability of collisions occurs, especially where there is high utilization. Once the medium is idle, CSMA/CA protocol causes each station to delay its transmission by a random backoff time, thereby minimizing the chance it will collide with those from other stations. The CSMA/CA protocol computes the random backoff time as the product of a constant, the slot time, times a pseudo-random number RN which has a range of values from zero to a collision window CW. The value of the collision window for the first try to access the network is CW 1 , which yields the first try random backoff time. If the first try to access the network by a station fails, then the CSMA/CA protocol computes a new CW by doubling the current value of CW as CW 2 =CW 1 times 2. The value of the collision window for the second try to access the network is CW 2 , which yields the second try random backoff time. This process by the CSMA/CA protocol of increasing the delay before transmission is called binary exponential backoff. The reason for increasing CW is to minimize collisions and maximize throughput for both low and high network utilization. Stations with low network utilization are not forced to wait very long before transmitting their frame. On the first car second attempt, a station will make a successful transmission. However, if the utilization of the network is high, the CSMA/CA protocol delays stations for longer periods to avoid the chance of multiple stations transmitting at the same time. If the second try to access the network fails, then the CSMA/CA protocol computes a new CW by again doubling the current value of CW as CW 3 =CW 1 times 4. The value of the collision window for the third try to access the network is CW 3 , which yields the third try random backoff time. The value of CW increases to relatively high values after successive retransmissions, under high traffic loads. This provides greater transmission spacing between stations waiting to transmit. Collision Avoidance Techniques Four general collision avoidance approaches have emerged: [1] Carrier Sense Multiple Access (CSMA) [see, F. Tobagi and L. Kleinrock, “Packet Switching in Radio Channels: Part I—Carrier Sense Multiple Access Models and their Throughput Delay Characteristics”, IEEE Transactions on Communications , Vol 23, No 12, Pages 1400-1416, 1975], [2] Multiple Access Collision Avoidance (MACA) [see, P. Karn, “MACA—A New Channel Access Protocol for Wireless Ad-Hoe Networks”, Proceedings of the ARRL/CRRL Amateur Radio Ninth Computer Networking Conference , Pages 134-140, 1990.], [3] their combination CSMA/CA, and [4] collision avoidance tree expansion. CSMA allows access attempts after sensing the channel for activity. Still, simultaneous transmit attempts lead to collisions, thus rendering the protocol unstable at high traffic loads. The protocol also suffers from the hidden terminal problem. The latter problem was resolved by the MACA protocol, which involves a three-way handshake [P. Karn, supra]. The origin node sends a request to send (RTS) notice of the impending transmission. A response is returned by the destination if the RTS notice is received successfully and the origin node proceeds with the transmission. This protocol also reduces the average delay as collisions are detected upon transmission of merely a short message, the RTS. With the length of the packet included in the RTS and echoed in the clear to send (CTS) messages, hidden terminals can avoid colliding with the transmitted message. However, this prevents the back-to-back re-transmission in case of unsuccessfully transmitted packets. A five-way handshake MACA protocol provides notification to competing sources of the successful termination of the transmission. [see, V. Bharghavan, A. Demers, S. Shenker, and L. Zhang, “MACAW: A media access protocol for wireless LANs, SIGCOMM ' 94, Pages 212-225, ACM, 1994.] CSMA and MACA are combined in CSMA/CA, which is MACA with carrier sensing, to give better performance at high loads. A four-way handshake is employed in the basic contention-based access protocol used in the Distributed Coordination Function (DCF) of the IEEE 802.11 Standard for Wireless LANs. [see, IEEE Standards Department, D3, “Wireless Medium Access Control and Physical Layer WG,” IEEE Draft Standard P 802.11 Wireless LAN , January 1996.] Collisions can be avoided by splitting the contending terminals before transmission is attempted. In the pseudo-Bayesian control method, each terminal determines whether it has permission to transmit using a random number generator and a permission probability “p” that depends on the estimated backlog. [see, R. L. Rivest, “Network control by Bayesian Broadcast”, IEEE Trans. Inform. Theory , Vol IT 25, pp. 505-515, September 1979] To resolve collisions, subsequent transmission attempts are typically staggered randomly in time using the following two approaches: binary tree and binary exponential backoff. Upon collision, the binary tree method requires the contending nodes to self-partition into two groups with specified probabilities. This process is repeated with each new collision. The order in which contending nodes transmit is determined either by serial or parallel resolution of the tree. [see, J. L. Massey, “Collision-resolution algorithms and random-access communications”, in Multi - User Communication Systems , G. Longo (ed.), CISM Courses and Lectures No. 265. New York: Springer 1982, pp. 73-137.] In the binary exponential backoff approach, a backoff counter tracks the number of pauses and hence the number of completed transmissions before a node with pending packets attempts to seize the channel. A contending node initializes its backoff counter by drawing a random value, given the backoff window size. Each time the channel is found idle, the backoff counter is decreased and transmission is attempted upon expiration of the backoff counter. The window size is doubled every time a collision occurs, and the backoff countdown starts again. [see, A. Tanenbaum, Computer Networks, 3 rd ed ., Upper Saddle River, N.J., Prentice Hall, 1996] The Distributed Coordination Function (DCF) of the IEEE 802.11 Standard for Wireless LANs employs a variant of this contention resolution scheme, a truncated binary exponential backoff, starting at a specified window and allowing up to a maximum backoff range below which transmission is attempted. [IEEE Standards Department, D3, supra] Different backoff counters may be maintained by a contending node for traffic to specific destinations. [Bharghavan, supra] In the IEEE 802.11 Standard, the channel is shared by a centralized access protocol, the Point Coordination Function (PCF), which provides contention-free transfer based on a polling scheme controlled by the access point (AP) of a basic service set (BSS). [IEEE Standards Department, D3, supra] The centralized access protocol gains control of the channel and maintains control for the entire contention-free period by waiting a shorter time between transmissions than the stations using the Distributed Coordination Function (DCF) access procedure. Following the end of the contention-free period, the DCF access procedure begins, with each station contending for access using the CSMA/CA method. The 802.11 MAC Layer provides both contention and contention-free access to the shared wireless medium. The MAC Layer uses various MAC frame types to implement its functions of MAC management, control, and data transmission. Each station and access point on an 802.11 wireless LAN implements the MAC Layer service, which enables stations to exchange packets. The results of sensing the channel to determine whether the medium is busy or idle, are sent to the MAC coordination function of the station. The MAC coordination also carries out a virtual carrier sense protocol based on reservation information found in the Duration Field of all frames. This information announces to all other stations, the sending station's impending use of the medium. The MAC coordination monitors the Duration Field in all MAC frames and places this information in the station's Network Allocation Vector (NAV) if the value is greater than the current NAV value. The NAV operates similarly to a timer, starting with a value equal to the Duration Field of the last frame transmission sensed on the medium, and counting down to zero. After the NAV reaches zero, the station can transmit, if its physical sensing of the channel indicates a clear channel. At the beginning of a contention-free period, the access point senses the medium, and if it is idle, it sends a Beacon packet to all stations. The Beacon packet contains the length of the contention-free interval. The MAC coordination in each member station places the length of the contention-free interval in the station's Network Allocation Vector (NAV), which prevents the station from taking control of the medium until the end of the contention-free period. During the contention-free period, the access point can send a polling message to a member station, enabling it to send a data packet to any other station in the BSS wireless cell. Quality of Service (QoS) Quality of service (QoS) is a measure of service quality provided to a customer. The primary measures of QoS are message loss, message delay, and network availability. Voice and video applications have the most rigorous delay and loss requirements. Interactive data applications such as Web browsing have less restrained delay and loss requirements, but they are sensitive to errors. Non-real-time applications such as file transfer, Email, and data backup operate acceptably across a wide range of loss rates and delay. Some applications require a minimum amount of capacity to operate at all, for example, voice and video. Many network providers guarantee specific QoS and capacity levels through the use of Service-Level Agreements (SLAs). An SLA is a contract between an enterprise user and a network provider that specifies the capacity to be provided between points in the network that must be delivered with a specified QoS. If the network provider fails to meet the terms of the SLA, then the user may be entitled a refund. The SLA is typically offered by network providers for private line, frame relay, ATM, or Internet networks employed by enterprises. The transmission of time-sensitive and data application traffic over a packet network imposes requirements on the delay or delay jitter, and the error rates realized; these parameters are referred to generically as the QoS (Quality of Service) parameters. Prioritized packet scheduling, preferential packet dropping, and bandwidth allocation are among the techniques available at the various nodes of the network, including access points, that enable packets from different applications to be treated differently, helping achieve the different quality of service objectives. Such techniques exist in centralized and distributed variations. The concern herein is with distributed mechanisms for multiple access in cellular packet networks or wireless ad hoc networks. Management of contention for the shared transmission medium must reflect the goals sought for the performance of the overall system. For instance, one such goal would be the maximization of goodput (the amount of good data transmitted as a fraction of the channel capacity) for the entire system, or of the utilization efficiency of the RF spectrum; another is the minimization of the worst-case delay. As multiple types of traffic with different performance requirements are combined into packet streams that compete for the same transmission medium, a multi-objective optimization is required. Ideally, one would want a multiple access protocol that is capable of effecting packet transmission scheduling as close to the optimal scheduling as possible, but with distributed control. Distributed control implies both some knowledge of the attributes of the competing packet sources and limited control mechanisms. To apply any scheduling algorithm in random multiple access, a mechanism must exist that imposes an order in which packets will seize the medium. For distributed control, this ordering must be achieved independently, without any prompting or coordination from a control node. Only if there is a reasonable likelihood that packet transmissions will be ordered according to the scheduling algorithm, can one expect that the algorithm's proclaimed objective will be attained. The above cited, copending patent application by Mathilde Benveniste, entitled “Tiered Contention Multiple Access (TCMA): A Method for Priority-Based Shared Channel Access”, describes the Tiered Contention Multiple Access (TCMA) distributed medium access protocol that schedules transmission of different types of traffic based on their QoS service quality specifications. This protocol makes changes to the contention window following the transmission of a frame, and therefore is also called Extended-DCF (E-DCF). During the contention window, the various stations on the network contend for access to the network. To avoid collisions, the MAC protocol requires that each station first wait for a randomly-chosen time period, called an arbitration time. Since this period is chosen at random by each station, there is less likelihood of collisions between stations. TCMA uses the contention window to give higher priority to some stations than to others. Assigning a short contention window to those stations that should have higher priority ensures that in most cases, the higher-priority stations will be able to transmit ahead of the lower-priority stations. TCMA schedules transmission of different types of traffic based on their QoS service quality specifications. As seen in FIG. 1 , which depicts the tiered contention mechanism, a station cannot engage in backoff countdown until the completion of an idle period of length equal to its arbitration time. The above cited, copending patent application by Mathilde Benveniste also applies TCMA to the use of the wireless access point as a traffic director. This application of the TCMA protocol is called the hybrid coordination function (HCF). In HCF, the access point uses a polling technique as the traffic control mechanism. The access point sends polling packets to a succession of stations on the network. The individual stations can reply to the poll with a packet that contains not only the response, but also any data that needs to be transmitted. Each station must wait to be polled. The access point establishes a polling priority based on the QoS priority of each station. What is needed in the prior art is a way to apply the hybrid coordination function (HCF) to wireless cells that have overlapping access points contending for the same medium. SUMMARY OF THE INVENTION In accordance with the invention, the Tiered Contention Multiple Access (TCMA) protocol is applied to wireless cells which have overlapping access points contending for the same medium. Quality of Service (QoS) support is provided to overlapping access points to schedule transmission of different types of traffic based on the service quality specifications of the access points. The inventive method reduces interference in a medium between overlapping wireless LAN cells, each cell including an access point station and a plurality of member stations. In accordance with the invention, the method assigns to a first access point station in a first wireless LAN cell, a first scheduling tag. The scheduling tag has a value that determines an accessing order for the cell in a transmission frame, with respect to the accessing order of other wireless cells. The scheduling tag value is deterministically set. The scheduling tag value can be permanently assigned to the access point by its manufacturer, it can be assigned by the network administrator at network startup, it can be assigned by a global processor that coordinates a plurality of wireless cells over a backbone network, it can be drawn from a pool of possible tag values during an initial handshake negotiation with other wireless stations, or it can be cyclically permuted in real-time, on a frame-by-frame basis, from a pool of possible values, coordinating that cyclic permutation with that of other access points in other wireless cells. An access point station in a wireless cell signals the beginning of an intra-cell contention-free period for member stations in its cell by transmitting a beacon packet. The duration of the intra-cell contention-free period is deterministically set. The member stations in the cell store the intra-cell contention-free period value as a Network Allocation Vector (NAV). Each member station in the cell decrements the value of the NAV in a manner similar to other backoff time values, during which it will delay accessing the medium. In accordance with the invention, the method assigns to the first access point station, a first inter-cell contention-free period value, which gives notice to any other cell receiving the beacon packet, that the first cell has seized the medium for the period of time represented by the value. The inter-cell contention-free period value is deterministically set. Further in accordance with the invention, any station receiving the beacon packet immediately broadcasts a contention-free time response (CFTR) packet containing a copy of the first inter-cell contention-free period value. In this manner, the notice is distributed to a second access point station in an overlapping, second cell. The second access point stores the first inter-cell contention-free period value as an Inter-BSS Network Allocation Vector (IBNAV). The second access point decrements the value of IBNAV in a manner similar to other backoff time values, during which it will delay accessing the medium. Still further in accordance with the invention, the method also assigns to first member stations in the first cell, a first shorter backoff value for high Quality of Service (QoS) data and a first longer backoff value for lower QoS data. The backoff time is the interval that a member station waits after the expiration of the contention-free period, before the member station contends for access to the medium. Since more than one member station in a cell may be competing for access, the actual backoff time for a particular station can be selected as one of several possible values. In one embodiment, the actual backoff time for each particular station is deterministically set, so as to reduce the length of idle periods. In another embodiment, the actual backoff time for each particular station is randomly drawn from a range of possible values between a minimum delay interval to a maximum delay interval. The range of possible backoff time values is a contention window. The backoff values assigned to a cell may be in the form of a specified contention window. High QoS data is typically isochronous data such as streaming video or audio data that must arrive at its destination at regular intervals. Low QoS data is typically file transfer data and email, which can be delayed in its delivery and yet still be acceptable. The Tiered Contention Multiple Access (TCMA) protocol coordinates the transmission of packets within a cell, so as to give preference to high QoS data over low QoS data, to insure that the required quality of service is maintained for each type of data. The method similarly assigns to a second access point station in a second wireless LAN cell that overlaps the first sell, a second contention-free period value longer than the first contention-free period value. The method also assigns to second member stations in the second cell, a second shorter backoff value for high QoS data and a second longer backoff value for lower QoS data. The first and second cells are considered to be overlapped when one or more stations in the first cell inadvertently receive packets from member stations or the access point of the other cell. The invention reduces the interference between the overlapped cells by coordinating the timing of their respective transmissions, while maintaining the TCMA protocol's preference for the transmission of high QoS data over low QoS data in each respective cell. During the operation of two overlapped cells, the method transmits a first beacon packet including the intra-cell contention-free period value (the increment to the NAV) and inter-cell contention-free period value (the CFTR), from the first access point to the first member stations in the first cell. The beacon packet is received by the member stations of the first cell and can be inadvertently received by at least one overlapped member station of the second cell. Each member station in the first cell increments its NAV with the intra-cell contention-free period value and stores the inter-cell contention-free period value as the CFTR. In accordance with the invention, each station that receives the first beacon packet, immediately responds by transmitting a first contention-free time response (CFTR) packet that contains a copy of the inter-cell contention-free period value (CFTR). A CFTR packet is transmitted from the first member stations in the first cell and also by the overlapped member stations of the second cell. The effect of the transmission of CFTR packets from member stations in the second cell is to alert the second access point and the second member stations in the second cell, that the medium has been seized by the first access point in the first cell. When the second access point in the second cell receives the CFTR packet it stores the a copy of the inter-cell contention-free period value as the IBNAV. Similar to a station's Network Allocation Vector (NAV), a first IBNAV is set at the second access point to indicate the time the medium will be free again. Also similar to the NAV, the first IBNAV is decremented with each succeeding slot, similar to the decrementing of other backoff times. When the second access point receives the first IBNAV representing the first cell's contention-free period value, the second access point must respect the first IBNAV value and delay transmitting its beacon packet and the exchange of other packets in the second cell until the expiration of the received, first IBNAV. When the second access point has decremented the first IBNAV to zero, the second access point transmits its second beacon packet including its second contention-free period values of NAV and a second IBNAV, to the second member stations in the second cell. Each station that receives the second beacon packet immediately responds by transmitting a second contention-free time response (CFTR) packet that contains a copy of the second IBNAV inter-cell contention-free period value. The second CFTR packet is transmitted from the second member stations in the second cell and also by the overlapped member stations of the first cell. The effect of the transmission of the second CFTR packets from overlapped member stations in the first cell is to alert the first access point and the first member stations in the first cell, that the medium has been seized by the second access point in the second cell. When the first access point in the first cell receives the CFTR packet it stores the a copy of the second IBNAV inter-cell contention-free period value, to indicate the time the medium will be free again. The second IBNAV is decremented with each succeeding frame, similar to the decrementing of other backoff times. The second member stations in the second cell wait for completion of the count down of their NAVs to begin the TCMA protocol of counting down the second shorter backoff for high QoS data and then transmitting second high QoS data packets. Meanwhile, the first access point in the first cell waits for completion of the count down of the second IBNAV inter-cell contention-free period before starting the countdown of its own NAV for its own intra-cell contention-free period. The first member stations in the first cell wait for the count down of their NAVs, to begin the TCMA protocol of counting down the first longer backoff for low QoS data and then transmitting first low QoS data. Meanwhile the second member stations are waiting for the TCMA protocol of counting down the second longer backoff for lower QoS data before transmitting the second lower QoS data. In this manner, interference in a medium between overlapping wireless LAN cells is reduced. Potential collisions between cells engaged in centralized access can be averted or resolved by the TCMA protocol. In accordance with the invention, deterministically set backoff delays are used, which tend to reduce the length of the idle periods. The possibility of coincident or overlapping contention-free periods between neighboring cells is eliminated through the use of an “interference sensing” method employing a new frame. The invention enables communication of channel occupancy information to neighboring access points. When a beacon packet is transmitted, and before transmission of any other data or polling packets, all stations hearing the beacon will respond by sending a frame, the contention-free time response (CFTR), that will contain the duration of the contention-free period found in the beacon. An access point in neighboring cells, or stations attempting contention-based channel access, which receive this message from a station in the cell overlapping region, are thus alerted that the channel has been seized by an access point. Similar to a station's Network Allocation Vector (NAV), an Inter-Cell Network Allocation Vector at the access point accordingly indicates when the time the channel will be free again. Unless the Inter-Cell Network Allocation Vector is reset, the access point will decrease its backoff value only after the expiration of the Inter-Cell Network Allocation Vector, according to the backoff countdown rules. In another aspect of the invention, potential collisions between different access points engaged in centralized access can be averted or resolved by using deterministic backoff delays, which avoid collisions between access points, and eliminate gaps between consecutive poll/response exchanges or contention-free bursts (CFBs) between the access point and its associated stations. The resulting invention applies the Tiered Contention Multiple Access (TCMA) protocol to wireless cells which have overlapping access points contending for the same medium. DESCRIPTION OF THE FIGURES FIG. 1 depicts the tiered contention mechanism. FIGS. 1A through 1J show the interaction of two wireless LAN cells which have overlapping access points contending for the same medium, in accordance with the invention. FIG. 1K shows a timing diagram for the interaction of two wireless LAN cells in FIGS. 1A through 1J , in accordance with the invention. FIG. 1L shows the IEEE 802.11 packet structure for a beacon packet, including the increment to the NAV period and the CFTR period, in accordance with the invention. FIG. 1M shows the IEEE 802.11 packet structure for a CFTR packet, including the CFTR period, in accordance with the invention. FIG. 2 illustrates the ordering of transmissions from three groups of BSSs. FIG. 3 illustrates how three interfering BSSs share the same channel for two consecutive frames. FIG. 4 illustrates how three interfering BSSs, each with two types of traffic of different priorities, share the same channel in two consecutive frames. FIG. 5 illustrates the possible re-use of tags. FIG. 6 illustrates the deterministic post-backoff. FIG. 7 shows the relationships of repeating sequences of CFBs. FIG. 8 illustrates the role of pegging in a sequence of CFBs by three overlapping access points. FIG. 9 illustrates the start-up procedure for a new access point, HC 2 , given an existing access point, HC 1 . FIG. 10 shows the relationship of repeating sequences of Tier I CFBs. FIG. 11 illustrates the start-up procedure for a new access point, HC 2 , given an existing access point, HC 1 . DISCUSSION OF THE PREFERRED EMBODIMENT The invention disclosed broadly relates to telecommunications methods and more particularly relates to Quality-of-Service (QoS) management in multiple access packet networks. Several protocols, either centralized or distributed can co-exist on the same channel through the Tiered Contention Multiple Access method. The proper arbitration time to be assigned to the centralized access protocol must satisfy the following requirements: (i) the centralized access protocol enjoys top priority access, (ii) once the centralized protocol seizes the channel, it maintains control until the contention-free period ends, (iii) the protocols are backward compatible, and (iv) Overlapping Basic Service Sets (OBSSs) engaged in centralized-protocol can share the channel efficiently. In accordance with the invention, the Tiered Contention Multiple Access (TCMA) protocol is applied to wireless cells which have overlapping access points contending for the same medium. Quality of Service (QoS) support is provided to overlapping access points to schedule transmission of different types of traffic based on the service quality specifications of the access points. The inventive method reduces interference in a medium between overlapping wireless LAN cells, each cell including an access point station and a plurality of member stations. FIGS. 1A through 1J show the interaction of two wireless LAN cells which have overlapping access points contending for the same medium, in accordance with the invention. The method assigns to a first access point station in a first wireless LAN cell, a first scheduling tag. The scheduling tag has a value that determines an accessing order for the cell in a transmission frame, with respect to the accessing order of other wireless cells. The scheduling tag value is deterministically set. The scheduling tag value can be permanently assigned to the access point by its manufacturer, it can be assigned by the network administrator at network startup, it can be assigned by a global processor that coordinates a plurality of wireless cells over a backbone network, it can be drawn from a pool of possible tag values during an initial handshake negotiation with other wireless stations, or it can be cyclically permuted in real-time, on a frame-by-frame basis, from a pool of possible values, coordinating that cyclic permutation with that of other access points in other wireless cells. The interaction of the two wireless LAN cells 100 and 150 in FIGS. 1A through 1J is shown in the timing diagram of FIG. 1K . The timing diagram of FIG. 1K begins at instant T 0 , goes to instant T 9 , and includes periods P 1 through P 8 , as shown in the figure. The various packets discussed below are also shown in FIG. 1K , placed at their respective times of occurrence. An access point station in a wireless cell signals the beginning of an intra-cell contention-free period for member stations in its cell by transmitting a beacon packet. FIG. 1A shows access point 152 of cell 150 connected to backbone network 160 , transmitting the beacon packet 124 . In accordance with the invention, the beacon packet 124 includes two contention-free period values, the first is the Network Allocation Vector (NAV) (or alternately its incremental value ΔNAV), which specifies a period value P 3 for the intra-cell contention-free period for member stations in its own cell. Member stations within the cell 150 must wait for the period P 3 before beginning the Tiered Contention Multiple Access (TCMA) procedure, as shown in FIG. 1K . The other contention-free period value included in the beacon packet 124 is the Inter-BSS Network Allocation Vector (IBNAV), which specifies the contention-free time response (CFTR) period P 4 . The contention-free time response (CFTR) period P 4 gives notice to any other cell receiving the beacon packet, such as cell 100 , that the first cell 150 has seized the medium for the period of time represented by the value P 4 . The beacon packet 124 is received by the member stations 154 A (with a low QoS requirement 164 A) and 154 B (with a high QoS requirement 164 B) in the cell 150 during the period from T 1 to T 2 . The member stations 154 A and 154 B store the value of ΔNAV=P 3 and begin counting down that value during the contention free period of the cell 150 . The duration of the intra-cell contention-free period ΔNAV=P 3 is deterministically set. The member stations in the cell store the intra-cell contention-free period value P 3 as the Network Allocation Vector (NAV). Each member station in the cell 150 decrements the value of the NAV in a manner similar to other backoff time values, during which it will delay accessing the medium. FIG. 1L shows the IEEE 802.11 packet structure 260 for the beacon packet 124 or 120 , including the increment to the NAV period and the CFTR period. The beacon packet structure 260 includes fields 261 to 267 . Field 267 specifies the ΔNAV value of P 3 and the CFTR value of P 4 . In accordance with the invention, the method assigns to the first access point station, a first inter-cell contention-free period value, which gives notice to any other cell receiving the beacon packet, that the first cell has seized the medium for the period of time represented by the value. The inter-cell contention-free period value is deterministically set. Further in accordance with the invention, any station receiving the beacon packet 124 immediately rebroadcasts a contention-free time response (CFTR) packet 126 containing a copy of the first inter-cell contention-free period value P 4 . The value P 4 specifies the Inter-BSS Network Allocation Vector (IBNAV), i.e., the contention-free time response (CFTR) period that the second access point 102 must wait, while the first cell 150 has seized the medium. FIG. 1B shows overlap station 106 in the region of overlap 170 transmitting the CFTR packet 126 to stations in both cells 100 and 150 during the period from T 1 to T 2 . FIG. 1M shows the IEEE 802.11 packet structure 360 for a CFTR packet 126 or 122 , including the CFTR period. The CFTR packet structure 360 includes fields 361 to 367 . Field 367 specifies the CFTR value of P 4 . In this manner, the notice is distributed to the second access point station 102 in the overlapping, second cell 100 . FIG. 1C shows the point coordinator in access point 152 of cell 150 controlling the contention-free period within the cell 150 by using the polling packet 128 during the period from T 2 to T 3 . In the mean time, the second access point 102 in the second cell 100 connected to backbone network 110 , stores the first inter-cell contention-free period value P 4 received in the CFTR packet 126 , which it stores as the Inter-BSS Network Allocation Vector (IBNAV). The second access point 102 decrements the value of IBNAV in a manner similar to other backoff time values, during which it will delay accessing the medium. Still further in accordance with the invention, the method uses the Tiered Contention. Multiple Access (TCMA) protocol to assign to first member stations in the first cell 150 , a first shorter backoff value for high Quality of Service (QoS) data and a first longer backoff value for lower QoS data. FIG. 1D shows the station 154 B in the cell 150 , having a high QoS requirement 164 B, decreasing its High QoS backoff period to zero and beginning TCMA contention to transmit its high QoS data packet 130 during the period from T 3 to T 4 . The backoff time is the interval that a member station waits after the expiration of the contention-free period P 3 , before the member station 154 B contends for access to the medium. Since more than one member station in a cell may be competing for access, the actual backoff time for a particular station can be selected as one of several possible values. In one embodiment, the actual backoff time for each particular station is deterministically set, so as to reduce the length of idle periods. In another embodiment, the actual backoff time for each particular station is randomly drawn from a range of possible values between a minimum delay interval to a maximum delay interval. The range of possible backoff time values is a contention window. The backoff values assigned to a cell may be in the form of a specified contention window. High QoS data is typically isochronous data such as streaming video or audio data that must arrive at its destination at regular intervals. Low QoS data is typically file transfer data and email, which can be delayed in its delivery and yet still be acceptable. The Tiered Contention Multiple Access (TCMA) protocol coordinates the transmission of packets within a cell, so as to give preference to high QoS data over low QoS data, to insure that the required quality of service is maintained for each type of data. The method similarly assigns to the second access point 102 station in the second wireless LAN cell 100 that overlaps the first sell 150 , a second contention-free period value CFTR=P 7 longer than the first contention-free period value CFTR=P 4 . FIG. 1E shows the second access point 102 in the cell 100 transmitting its beacon packet 120 including its contention-free period values of NAV (P 6 ) and IBNAV (P 7 ), to the member stations 104 A (with a Iow QoS requirement 114 A), 104 B (with a high QoS requirement 114 B) and 106 in the cell 100 during the period from T 4 to T 5 . FIG. 1F shows that each station, including the overlap station 106 , that receives the second beacon packet 120 , immediately responds by retransmitting a second contention-free time response (CFTR) packet 122 that contains a copy of the second inter-cell contention-free period value P 7 during the period from T 4 to T 5 . FIG. 1G shows the point coordinator in access point 102 of cell 100 controlling the contention-free period within cell 100 using the polling packet 132 during the period from T 5 to T 6 . The method uses the Tiered Contention Multiple Access (TCMA) protocol to assign to second member stations in the second cell 100 , a second shorter backoff value for high QoS data and a second longer backoff value for lower QoS data. FIG. 1H shows the station 104 B in the cell 100 , having a high QoS requirement 114 B, decreasing its High QoS backoff period to zero and beginning TCMA contention to transmit its high QoS data packet 134 during the period from T 6 to T 7 . FIG. 1I shows the first member stations 154 A and 154 B in the first cell 150 waiting for the count down of their NAVs, to begin the TCMA protocol of counting down the first longer backoff for low QoS data and then transmitting first low QoS data 136 during the period from T 7 to T 8 . FIG. 1J shows the second member stations 104 A, 104 B, and 106 are waiting for the TCMA protocol of counting down the second longer backoff for lower QoS data before transmitting the second lower QoS data 138 during the period from T 8 to T 9 . The first and second cells are considered to be overlapped when one or more stations in the first cell can inadvertently receive packets from member stations or the access point of the other cell. The invention reduces the interference between the overlapped cells by coordinating the timing of their respective transmissions, while maintaining the TCMA protocol's preference for the transmission of high QoS data over low QoS data in each respective cell. During the operation of two overlapped cells, the method in FIG. 1A transmits a first beacon packet 124 including the intra-cell contention-free period value (the increment to the NAV) and inter-cell contention free period value (the CFTR), from the first access point 152 to the first member stations 154 B and 154 A in the first cell 150 . The beacon packet is received by the member stations of the first cell and inadvertently by at least one overlapped member station 106 of the second cell 100 . Each member station 154 B and 154 A in the first cell increments its NAV with the intra-cell contention-free period value P 3 and stores the inter-cell contention-free period value P 4 as the CFTR. In accordance with the invention, each station that receives the first beacon packet 124 , immediately responds by transmitting a first contention-free time response (CFTR) packet 126 in FIG. 1B that contains a copy of the inter-cell contention-free period P 4 value (CFTR). A CFTR packet 126 is transmitted from the first member stations 15413 and 154 A in the first cell 150 and also by the overlapped member stations 106 of the second cell 100 . The effect of the transmission of CFTR packets 126 from member stations 106 in the second cell 100 is to alert the second access point 102 and the second member stations 104 A and 104 B in the second cell 100 , that the medium has been seized by the first access point 152 in the first cell 150 . When the second access point 102 in the second cell 100 receives the CFTR packet 126 it stores the a copy of the inter-cell contention-free period value P 4 as the IBNAV. Similar to a station's Network Allocation Vector (NAV), an IBNAV is set at the access point to indicate the time the medium will be free again. Also similar to the NAV, the IBNAV is decremented with each succeeding slot, similar to the decrementing of other backoff times. When the second access point receives a new IBNAV representing the first cell's contention-free period value, then the second access point must respect the IBNAV value and delay transmitting its beacon packet and the exchange of other packets in the second cell until the expiration of the received, IBNAV. Later, as shown in FIG. 1E , when the second access point 102 transmits its second beacon packet 120 including its second contention-free period values of NAV (P 6 ) and IBNAV (P 7 ), to the second member stations 104 A, 104 B and 106 in the second cell 100 , each station that receives the second beacon packet, immediately responds by transmitting a second contention-free time response (CFTR) packet 122 in FIG. 1F , that contains a copy of the second inter-cell contention-free period value P 7 . A CFTR packet 122 is transmitted from the second member stations 104 A, 104 B and overlapped station 106 in the second cell and also by the overlapped member stations of the first cell. The effect of the transmission of CFTR packets from overlapped member station 106 is to alert the first access point 152 and the first member stations 145 A and 154 B in the first cell 150 , that the medium has been seized by the second access point 102 in the second cell 100 . When the first access point 152 in the first cell 150 receives the CFTR packet 122 it stores the a copy of the second inter-cell contention-free period value P 7 as an IBNAV, to indicate the time the medium will be free again. The IBNAV is decremented with each succeeding slot, similar to the decrementing of other backoff times. The second member stations 104 A, 104 B, and 106 in the second cell 100 wait for completion of the count down of their NAVs to begin the TCMA protocol of counting down the second shorter backoff for high QoS data and then transmitting second high QoS data packets, as shown in FIGS. 1G and 1H . Meanwhile, the first access point 152 in the first cell 150 waits for completion of the count down of the second inter-cell contention-free period P 7 in its IBNAV in FIGS. 1G and 1H before starting the countdown of its own NAV for its own intra-cell contention-free period. The first member stations 154 A and 154 B in the first cell 150 wait for the count down of their NAVs, to begin the TCMA protocol of counting down the first longer backoff for low QoS data and then transmitting first low QoS data in FIG. 1I . Meanwhile the second member stations 104 A, 104 B, and 106 are waiting for the TCMA protocol of counting down the second longer backoff for lower QoS data before transmitting the second lower QoS data 138 in FIG. 1J . In this manner, interference in a medium between overlapping wireless LAN cells is reduced. DETAILED DESCRIPTION OF THE INVENTION TCMA can accommodate co-existing Extended Distributed Coordination Function (E-DCF) and centralized access protocols. In order to ensure that the centralized access protocol operating under Hybrid Coordination Function (HCF) is assigned top priority access, it must have the shortest arbitration time. Its arbitration time is determined by considering two additional requirements: uninterrupted control of the channel for the duration of the contention-free period, and backward compatibility. Uninterrupted Contention-Free Channel Control The channel must remain under the control of the centralized access protocol until the contention-free period is complete once it has been seized by the centralized access protocol. For this, it is sufficient that the maximum spacing between consecutive transmissions exchanged in the centralized access protocol, referred to as the central coordination time (CCT), be shorter than the time the channel must be idle before a station attempts a contention-based transmission following the end of a busy-channel time interval. The centralized access protocol has a CCT equal to the Priority Interframe Space (PIFS). Hence, no station may access the channel by contention, using either the distributed coordination function (DCF) or Extended-DCF (E-DCF) access procedure, before an idle period of length of the DCF Interframe Space (DIFS) equaling PIFS+1 (slot time) following the end of a busy-channel time interval. This requirement is met by DCF. For E-DCF, it would be sufficient for the Urgency Arbitration Time (UAT) of a class j, UATj, to be greater than PIFS for all classes j>1. Backward Compatibility Backward compatibility relates to the priority treatment of traffic handled by enhanced stations (ESTAs) as compared to legacy stations (STAs). In addition to traffic class differentiation, the ESTAs must provide certain traffic classes with higher or equal priority access than that provided by the STAs. That means that certain traffic classes should be assigned a shorter arbitration times than DIFS, the de facto arbitration time of legacy stations. Because the time in which the “clear channel assessment” (CCA) function can be completed is set at the minimum attainable for the IEEE 802.11 physical layer (PHY) specification, the arbitration times of any two classes of different priority would have to be separated by at least one “time slot”. This requirement implies that the highest priority traffic class would be required to have an arbitration time equal to DIFS−1 (slot time)=PIFS. Though an arbitration time of PIES appears to fail meeting the requirement for uninterrupted control of the channel during the contention-free period, it is possible for an ESTA to access the channel by E-DCF using an arbitration time of PIES and, at the same time, allow priority access to the centralized access protocol at PIFS. This is achieved as follows. Contention-based transmission is restricted to occur after a DIES idle period following the end of a busy channel period by ensuring that the backoff value of such stations is drawn from a random distribution with lower bound that is at least 1. Given that all backlogged stations resume backoff countdown after a busy-channel interval with a residual backoff of at least 1, an ESTA will attempt transmission following completion of the busy interval only after an idle period equal to PIFS+1 (slot time)=DIFS. This enables the centralized access protocol to maintain control of the channel without colliding with contention-based transmissions by ESTAs attempting to access the channel using E-DCF. To see that the residual backoff value of a backlogged station will be greater than or equal to 1 whenever countdown is resumed at the end of a busy channel period, consider a station with a backoff value m>0. The station will decrease its residual backoff value by 1 following each time slot during which the channel remains idle. If m reaches 0 before countdown is interrupted by a transmission, the station will attempt transmission. The transmission will either fail, leading to a new backoff being drawn, or succeed. Therefore, countdown will be resumed after the busy-channel period ends, only with a residual backoff of 1 or greater. Consequently, if the smallest random backoff that can be drawn is 1 or greater, an ESTA will always wait for at least a DIFS idle interval following a busy period before it attempts transmission. Only one class can be derived with priority above legacy through differentiation by arbitration time alone, by using the arbitration time of PIFS. Multiple classes with that priority can be obtained by differentiation through other parameters, such as the parameters of the backoff time distribution; e.g. the contention window size. For all the classes so derived, a DIFS idle period will follow a busy channel interval before the ESTA seizes the channel if the restriction is imposed that the backoff value of such stations be drawn from a random distribution with lower bound of at least 1. Because PIFS is shorter than DIFS, the traffic classes with arbitration time equal to PIFS will have higher access priority than the traffic classes with arbitration time equal to DIFS. As seen in FIG. 1 , which depicts the tiered contention mechanism, a station cannot engage in backoff countdown until the completion of an idle period of length equal to its arbitration time. Therefore, a legacy station will be unable to resume backoff countdown at the end of a busy-channel interval, if an ESTA with arbitration time of PIFS has a residual backoff of 1. Moreover, a legacy station will be unable to transmit until all higher-priority ESTAs with residual backoff of 1 have transmitted. Only legacy stations that draw a backoff value of 0 will transmit after a DIFS idle period, thus competing for the channel with the higher priority stations. This occurs only with a probability less than 3 percent, since the probability of drawing a random backoff of 0 from the range [0,31] is equal to 1/32. Top Priority for the Centralized Access Protocol For the centralized access protocol to enjoy the highest priority access, it must have an arbitration time shorter than PIFS by at least a time slot; that is, its arbitration time must equal PIFS−1 (slot time)=the Short Interframe Space (SIFS). As in the case of the highest traffic priority classes for ESTAs accessing the channel by E-DCF, the random backoff values for the beacon of the centralized access protocol must be drawn from a range with a lower bound of at least 1. Using the same reasoning as above, the centralized access protocol will not transmit before an idle period less than PIFS=SIFS+1 (slot time), thus respecting the inter-frame spacing requirement for a SIFS idle period within frame exchange sequences. Consequently, the shorter arbitration time assigned to the centralized access protocol ensures that it accesses the channel with higher priority than any station attempting contention-based access through E-DCF, while at the same time respecting the SIFS spacing requirement. It should be noted that while collisions are prevented between frame exchanges during the contention-free period, collisions are possible both between the beacons of centralized access protocols of different BSSs located within interfering range [having coverage overlap], and between the beacon of a centralized access protocol and stations accessing the channel by contention using E-DCF. The probability of such collisions is low because higher priority nodes with residual backoff value m equal to 1 always seize the channel before lower priority nodes. Inter-access point collisions are resolved through the backoff procedure of TCMA. Inter-Access Point Contention Potential collisions between BSSs engaged in centralized access can be averted or resolved by a backoff procedure. The complication arising here is that a random backoff delay could result in idle periods longer periods than the SIFS+1 (slot time)=PIFS, which is what ensures priority access to the centralized protocol over E-DCF traffic contention-based traffic. Hence, the collisions with contention-based traffic would occur. Using short backoff windows in order to avoid this problem would increase the collisions experienced. In accordance with the invention, deterministically set backoff delays are used, which tend to reduce the length of the idle periods. Another aspect of inter-BSS interference that affects the performance of centralized protocols adversely is the possible interruption with a collision of what starts as an interference-free poll/response exchange between the access point and its associated stations. The possibility of coincident or overlapping contention-free periods between neighboring BSSs is eliminated through the use of an “interference sensing” method employing a new frame. Deterministic Backoff Procedure for the Centralized Access Protocol A modified backoff procedure is pursued for the beacons of the centralized access protocols. A backoff counter is employed in the same way as in TCMA. But while the backoff delay in TCMA is selected randomly from a contention window, in the case of the centralized access protocol beacons, the backoff value is set deterministically. Scheduling of packet transmission occurs once per frame, at the beginning of the frame. Only the packets queued at the start of a frame will be transmitted in that frame. It is assumed that BSSs are synchronized. A means for achieving such synchronization is through the exchange of messages relayed by boundary stations [stations in the overlapping regions of neighboring BSSs]. The backoff delay is selected through a mechanism called “tag scheduling”. Tags, which are ordinal labels, are assigned to different BSSs. BSSs that do not interfere with one another may be assigned the same tag, while BSSs with the potential to interfere with one another must receive different tags. For each frame, the tags are ordered in a way that is known a priori. This order represents the sequence in which the BSS with a given tag will access the channel in that frame. The backoff delay increases with the rank of the “tag” that has been assigned to the BSS for the current frame, as tags are permuted to give each group of BSS with the same tag a fair chance at the channel. For instance, a cyclic permutation for three tags, t=1, 2, 3, would give the following ordering: 1, 2, 3 for the first frame, 3, 1, 2 next, and then 2, 3, 1. One could also use other permutation mechanisms that are adaptive to traffic conditions and traffic priorities. The difference in the backoff delays corresponding to two consecutive tags is one time slot. FIG. 2 illustrates the ordering of transmissions from three groups of BSSs. A backoff counter is associated with each backoff delay. It is decreased according to the rules of TCMA using the arbitration time of Short Interframe Space (SIFS) as described in the preceding section. That is, once the channel is idle for a time interval equal to SIFS, the backoff counter associated with the centralized protocol of the BSS is decreased by 1 for each slot time the channel is idle. Access attempt occurs when the backoff counter expires. The minimum backoff value associated with the highest-ranking tag is 1. FIG. 3 illustrates how three interfering BSSs share the same channel for two consecutive frames. The tags assigned in each of the two frames are (1, 2), (2, 3), and (3, 1) for the three BSSs, respectively. The backoff delays for the three tags are 1, 2, and 3 time slots. When the channel is seized by the centralized protocol of a BSS, it engages in the polling and transmission functions for a time interval, known as the contention-free period. Once the channel has been successfully accessed that way, protection by the Network Allocation Vector (NAV) prevents interference from contention based traffic originating within that BSS. Avoidance of interference from neighboring BSS is discussed below. A maximum limit is imposed on the reservation length in order to even out the load on the channel from different BSSs and allow sufficient channel time for contention-based traffic. It is important to note the advantage of using deterministic backoff delays, versus random. Assuming an efficient (i.e., compact) tag re-use plan, deterministic backoff delays increase the likelihood that a beacon will occur precisely after an idle period of length SIFS+1=PIFS. This will enable the centralized protocol to gain access to the channel, as a higher priority class should, before contention-based traffic can access the channel at DIFS=PIFS+1. Using a random backoff delay instead might impose a longer idle period and hence, give rise to collisions with contention-based traffic. Use of short backoff windows to avoid this problem would be ill advised, since that would result in collision between the various BSS beacons. Though the backoff delays are set in a deterministic manner, there are no guarantees that collisions will always be avoided. Unless the duration of the contention-free period is the same for all BSSs, there is the possibility that interfering BSSs will attempt to access the channel at once. In case of such a collision, the backoff procedure starts again with the backoff delay associated with the tag assigned to the BSS, decreased by 1, and can be repeated until expiration of the frame. At the start of a new frame, a new tag is assigned to the BSS according to the pre-specified sequence, and the deferral time interval associated with the new tag is used. Collisions are also possible if tag assignments are imperfect (interfering BSSs are assigned the same tag). In the event of such a collision, transmission should be retried with random backoff. In order to deal with either type of collision, resolution occurs by drawing a random delay from a contention window size that increases with the deterministic backoff delay associated with the tag in that frame. Though random backoff is used in this event, starting with deterministic backoff helps reduce contention time. In a hybrid scenario, random backoff can be combined with tag scheduling. Instead of using backoff delays linked to the rank of a tag in a frame, the contention window size from which the backoff delay is drawn would increase with decreasing rank. The advantage of such an approach is to relax the restrictions on re-use by allowing the possibility that potentially interfering stations will be assigned the same tag. The disadvantage is that the Inter-BSS Contention Period (IBCP) time needed to eliminate contention by E-DCF traffic increases. Interference Sensing Interference sensing is the mechanism by which the occupancy status of a channel is determined. The access point only needs to know of channel activity in interfering BSSs. The best interference sensing mechanism is one that ensures that the channel is not used simultaneously by potentially interfering users. This involves listening to the channel by both the access point and stations. If the access point alone checks whether the channel is idle, the result does not convey adequate information on the potential for interference at a receiving station, nor does it address the problem of interference caused to others by the transmission, as an access point may not be able to hear transmissions from its neighboring access points, yet there is potential of interference to stations on the boundary of neighboring BSSs. Stations must detect neighboring BSS beacons and forward the information to their associated access point. However, transmission of this information by a station would cause interference within the neighboring BSS. In order to enable communication of channel occupancy information to neighboring access points, the invention includes the following mechanism. When a beacon packet is transmitted, and before transmission of any other data or polling packets, all stations hearing the beacon will respond by sending a frame, the contention-free time response (CFTR), that will contain the duration of the contention-free period found in the beacon. An access point in neighboring BSSs, or stations attempting contention-based channel access, that receive this message from a station in the BSS overlapping region are thus alerted that the channel has been seized by a BSS. Similar to a station's Network Allocation Vector (NAV), an Inter-Cell Network Allocation Vector, also referred to herein as an inter-BSS NAV (IBNAV), is set at the access point, accordingly, indicating the time the channel will be free again. Unless the IBNAV is reset, the access point will decrease its backoff value only after the expiration of the IBNAV, according to the backoff countdown rules. Alternatively, if beacons are sent at fixed time increments, receipt of the contention-free time response (CFTR) frame would suffice to extend the IBNAV. The alternative would be convenient in order to obviate the need for full decoding of the CFTR frame. It is necessary, however, that the frame type of CFTR be recognizable. Contention by E-DCF traffic while various interfering BSSs attempt to initiate their contention-free period can be lessened by adjusting the session length used to update the NAV and IBNAV. The contention-free period length is increased by a period Inter-BSS Contention Period (IBCP) during which the access points only will attempt access of the channel using the backoff procedure, while ESTAs wait for its expiration before attempting transmission. This mechanism can reduce the contention seen by the centralized protocols when employing either type of backoff delay, random or deterministic. With deterministic backoff delays, IBCP is set equal to the longest residual backoff delay possible, which is T(slot time), where T is the number of different tags. Given reasonable re-use of the tags, the channel time devoted to the IBCP would be less with deterministic backoff delays, as compared to the random. QoS Management A QoS-capable centralized protocol will have traffic with different time delay requirements queued in different priority buffers. Delay-sensitive traffic will be sent first, followed by traffic with lower priority. Tag scheduling is used again, but now there are two or more backoff values associated with each tag, a shorter value for the higher priority traffic and longer ones for lower priority. A BSS will transmit its top priority packets first, as described before. Once the top priority traffic has been transmitted, there would be further delay before the ESS would attempt to transmit lower priority traffic in order to give neighboring BSSs a chance to transmit their top priority packets. As long as any of the deferral time intervals for low-priority traffic is longer than the deferral time intervals for higher priority traffic of any tag, in general all neighboring BSSs would have a chance to transmit all pending top-priority packets before any lower-priority packets are transmitted. FIG. 4 illustrates how three interfering BSSs, each with two types of traffic of different priorities, share the same channel in two consecutive frames. As before, the tags assigned in each of the two frames are (1, 2), (2, 3), and (3, 1) for the three BSSs, respectively. The deferral times for the top priority traffic are 1, 2, and 3 time slots for tags 1, 2, and 3, respectively. The deferral times for the higher priority traffic are 4, 5, and 6 time slots for tags 1, 2, and 3, respectively. Tag Assignments A requirement in assigning tags to BSS is that distinct tags must be given to user entities with potential to interfere. This is not a difficult requirement to meet. In the absence of any information, a different tag could be assigned to each user entity. In that case, non-interfering cells will use the channel simultaneously even though they have different tags. Interference sensing will enable reuse of the channel by non-interfering BSSs that have been assigned different tags. There are advantages, however, in reducing the number of different tags. For instance, if the interference relationships between user entities are known, it is advantageous to assign the same tag to non-interfering BSS, and thus have a smaller number of tags. The utilization of bandwidth, and hence total throughput, would be greater as shorter deferral time intervals leave more of the frame time available for transmission. Moreover, an efficient (i.e., compact) tag re-use plan will decrease the likelihood of contention between the centralized protocol beacons of interfering BSSs contenting for access and E-DCF traffic. This problem is mitigated by using the IBCP time in the IBNAV, but re-use will reduce the length of this time. The assignment of tags to cells can be done without knowledge of the location of the access points and/or the stations. Tag assignment, like channel selection can be done at the time of installation. And again, like dynamic channel selection, it can be selected by the access point dynamically. RF planning, which processes signal-strength measurements can establish re-use groups and thus reduce the required number of tags. FIG. 5 , which includes FIGS. 5( a ) and 5 ( b ), illustrates the possible re-use of tags. In FIG. 5( a ), the access points are located at ideal spots on a hexagonal grid to achieve a regular tessellating pattern. In FIG. 5( b ), the access points have been placed as convenient and tags are assigned to avoid overlap. Imperfect tag assignments will lead to collisions between the access points, but such collisions can be resolved. To recap, arbitration times have been assigned to a centralized access protocol that co-exists with ESTAs accessing the channel through E-DCF. The centralized access protocol has the top priority, while E-DCF can offer traffic classes with priority access both above and below that provided by legacy stations using DCF. Table 1 illustrates the parameter specification for K+1 different classes according to the requirements given above. The centralized access protocol is assigned the highest priority classification, and hence the shortest arbitration time The top k−1 traffic classes for the E-DCF have priority above legacy but below the centralized access protocol; they achieve differentiation through the variation of the contention window size as well as other parameters. E-DCF traffic classes with priority above legacy have a lower bound, rLower, of the distribution from which backoff values are drawn that is equal to 1 or greater. Differentiation for classes with priority below legacy is achieved by increasing arbitration times; the lower bound of the random backoff distribution can be 0. BSSs within interfering range of one another compete for the channel through a deterministic backoff procedure employing tag scheduling, which rotates the backoff value for fairness among potentially interfering BSS. Re-use of a tag is permitted in non-interfering BSS. Multiple queues with their own backoff values enable prioritization of different QoS traffic classes. Contention-Free Bursts In accordance with the invention, potential collisions between different BSSs engaged in centralized access can be averted/resolved by deterministic backoff delays, which avoid collisions between access points, and eliminate gaps between consecutive poll/response exchanges between the access point and its associated stations. These are referred to as contention-free bursts (CFBs). Deterministic Backoff Procedure for the Centralized Access Protocol A modified backoff procedure is pursued for the beacons of the centralized access protocols. A backoff counter is employed in the same way as in TCMA. But while the backoff delay in TCMA is selected randomly from a contention window, in the case of the centralized access protocol beacons, the backoff value is set deterministically to a fixed value Bkoff, at the end of its contention-free session. Post-backoff is turned on. The backoff counter is decreased according to the rules of TCMA using the arbitration time AIFS=SIFS as described in the preceding section. That is, once the channel is idle for a time interval equal to SIFS, the backoff counter associated with the centralized protocol of the BSS is decreased by 1 for each slot time the channel is idle. Access attempt occurs when the backoff counter expires. An HC will restart its backoff after completing its transmission. The deterministic post-backoff procedure is illustrated in FIG. 6 . When the channel is seized by the centralized protocol of a BSS, it engages in the polling and transmission functions for a time interval, known as the contention-free period. Once the channel has been successfully accessed that way, protection by the NAV prevents interference from contention based traffic originating in the BSS. Avoidance of interference from neighboring BSS is discussed below. Non-Conflicting Contiguous Sequences of CFBs As long as the value of Bkoff is greater than or equal to the maximum number of interfering BSS, it is possible for the contention-free periods of a cluster of neighboring/overlapping BSSs to repeat in the same order without a collision between them. CFBs of different BSSs can be made to follow one another in a contiguous sequence, thus maximizing access of the centralized protocol to the channel. This can be seen as follows. Given a sequence of successful CFBs initiated by different BSSs, subsequent CFBs will not conflict because the follower's backoff counter always exceeds that of the leader by at least 1. If the previous CFBs were contiguous (that is, if consecutive CFBs were separated by idle gaps of length PIFS, the new CFBs will be also continuous because the follower's backoff delay exceeds that of the leader by exactly 1. Channel access attempts by E-DCF stations require an idle gap of length equal to DIFS or greater. FIG. 7 shows the relationships of repeating sequences of CFBs. In order to maintain contiguity, an HC that does not have any traffic to transmit when its backoff expires, it will transmit a short packet—a “peg”—and then engage in post-backoff. This way no gaps of length DIFS+1 are left idle until all HCs have completed one CFB per cycle, and restarted the backoff countdown procedure. E-DCF stations are thus prevented from seizing the channel until each BSS completes at least one CFB per cycle. FIG. 8 illustrates the role of pegging in a sequence of CFBs by three overlapping access points. Finally it is shown how such a contiguous sequence can constructed by analyzing how a new access point initiates its first CFB. Every time a new access point is installed, it must find its position in the repeating sequence of CFBs. The new access point listens to the channel for the desired cycle, trying to recognize the sequence. It listens for an “idle” PIFS following a busy channel. When that occurs, or after counting Bkoff time slots, whichever comes first, the new access point starts looking for the first idle longer than PIFS, which signifies the end of the sequence of CFBs. As long as the Bkoff is greater than the number of interfering BSS, there will always be such an idle period. The access point sets its post-backoff delay so that it transmits always right at the end of the CFB sequence. That is, if at time t, an idle>PIFS has been detected, the access point's backoff at time t is Bkoff−x(t), where x(t) is the number of idle time slots after PIFS. FIG. 9 illustrates this start-up procedure for a new access point, HC 2 , given an existing access point, HC 1 . Interference Sensing Interference sensing is the mechanism by which the occupancy status of a channel is determined. The access point only needs to know of channel activity in interfering BSSs. The best interference sensing mechanism is one that ensures that the channel is not used simultaneously by potentially interfering users. This involves listening to the channel by both the access point and stations. If the access point alone checks whether the channel is idle, the result does not convey adequate information on the potential for interference at a receiving station, nor does it address the problem of interference caused to others by the transmission, as an access point may not be able to hear transmissions from its neighboring access points, yet there is potential of interference to stations on the boundary of neighboring BSS. Stations must detect neighboring BSS beacons and forward the information to their associated access point. However, transmission of this information by a station would cause interference within the neighboring BSS. In order to enable communication of channel occupancy information to neighboring access points, the following mechanism is proposed. When a beacon packet is transmitted, and before transmission of any other data or polling packets, all stations not associated with the access point that hear the beacon will respond by sending a frame, the contention-free time response (CFTR), that will contain the duration of the contention-free period found in the beacon. An associated station will transmit the remaining duration of the contention-free period when polled. An access point in neighboring BSSs, or stations attempting contention-based channel access, that receive this message from a station in the BSS overlapping region are thus be alerted that the channel has been seized by a BSS. Similar to a station's NAV, an inter-BSS NAV (IBNAV) will be set at the access point accordingly indicating the time the channel will be free again. Unless the IBNAV is reset, the access point will decrease its backoff value only after the expiration of the IBNAV, according to the backoff countdown rules. Alternatively, if beacons are sent at fixed time increments, receipt of the CFTR frame would suffice to extend the IBNAV. The alternative would be convenient in order to obviate the need for full decoding of the CFTR frame. It is necessary, however, that the frame type of CFTR be recognizable. Contention by E-DCF traffic while various interfering BSSs attempt to initiate their contention-free period can be lessened by adjusting the session length used to update the NAV and IBNAV. The contention-free period length is increased by a period IBCP (inter-BSS contention period) during which the access points only will attempt access of the channel using the backoff procedure, while ESTAs wait for its expiration before attempting transmission. This mechanism can reduce the contention seen by the centralized protocols when employing either type of backoff delay—random or deterministic. QoS Management A QoS-capable centralized protocol will have traffic with different time delay requirements queued in different priority buffers. Delay-sensitive traffic will be sent first, followed by traffic with lower priority. A BSS will schedule transmissions from separate queues so that the QoS requirements are met. It will transmit its top priority packets first, as described before. Once the top priority traffic has been transmitted, the BSS would attempt to transmit lower priority traffic in the CFBs allotted. Three parameters are employed to help manage QoS. The deterministic backoff delay, Bkoff, and the maximum length of a CFB and of a DCF transmission. Since these parameters determine the relative allocation of the channel time between the centralized and distributed protocols, they can be adjusted to reflect the distribution of the traffic load between the two protocols. It must be kept in mind, however, that the same value of Bkoff should be used by all interfering BSSs. QoS Guarantees To enable high priority traffic to be delivered within guaranteed latency limits, a variation of the above method is described. CFBs of an access point are separated into two types, or tiers. The first contains time sensitive data and is sent when the period TXdt expires. The second tier contains time non-sensitive traffic and is sent when the backoff counter expires as a result of the countdown procedure. When all neighboring BSS have a chance to transmit their time sensitive traffic, the channel is available for additional transmissions before needing to transmit time-sensitive traffic again. Lower priority contention-free data can be then transmitted, using a backoff-based procedure. Tier II CFBs can be initiated in various methods. Two will be described here. They are: (1) random post-backoff, and (2) deterministic post-backoff. Both methods use the same AIFS used for top-priority EDCF transmissions, in order to avoid conflict with Tier I CFBs (i.e. an AIFS=PIFS). Conflict with top priority EDCF transmissions can be mitigated in case (1) or prevented in case (2) through the use of the IBNAV with an IBCP. Random post-backoff assigns an access point a backoff drawn from a prespecified contention window. A short contention window would lead to conflicts between Tier II CFBs. Along contention window reduces the conflict between interfering BSS attempting to access the channel at once. Long backoff values would reduce the fraction of the time the channel carries CFBs. Furthermore, the gaps created by multiple consecutive idle slots make room for DCF transmissions, reducing further the channel time available to CFBs. A long IBCP value would alleviate some of the conflict with DCF transmissions. Deterministic post-backoff eliminates the problems present with random post-backoff. Conflicts with top priority EDCF transmissions can be prevented with an IBCP of 1. Moreover, as explained above, the Tier II CFBs generated by this method, do not conflict with one another and form contiguous repeating sequences. Non-Conflicting Contiguous Sequences of Tier I CFBs Periodic transmission is achieved by maintaining a timer which is reset at the desired period TXdt as soon as the timer expires. A CFB is initiated upon expiration of the timer. As long as Tier I contention-free periods are all made the same size (by adding time non-critical traffic), which is not less than the maximum DCF transmission or Tier II CFB length, it is possible for the contention-free periods of a cluster of neighboring/overlapping BSSs to repeat in the same order without a collision between them. CFBs of different BSSs can be made to follow one another in a contiguous sequence, thus maximizing access of the centralized protocol to the channel. This can be seen as follows. Given a sequence of successful CFBs initiated by different BSSs, subsequent CFBs will not conflict because their timers will expire at least TICFBLength apart. If the leading access point's timer expires while the channel is busy, it will be able to start a new CFB before the follower HC because DCF transmissions are of equal or shorter length, and Type II CFBs have equal or shorter length. If the previous CFBs were contiguous (that is, if consecutive CFBs were separated by idle gaps of length PIFS), the new CFBs will be also continuous because the follower's timer will expire on or before the completion of the leader's CFB because their CFBs have the same length. Channel access attempts by E-DCF stations or Tier II CFBs require an idle gap of length equal to DIFS or greater, and hence they cannot be interjected. FIG. 10 shows the relationship of repeating sequences of Tier I CFBs. Finally it is shown how such a contiguous sequence can constructed by analyzing how a new access point initiates its first Tier I CFB. Every time a new access point is installed, it must find its position in the repeating sequence of CFBs. The new access point listens to the channel for the desired cycle, trying to recognize the sequence. It listens for an “idle” PIFS following a busy channel. When that occurs, or after a period TXdt, whichever comes first, the new access point starts looking for the first idle longer than PIFS, which signifies the end of the sequence of Tier I CFBs. As long as the TXdt is greater than the number of interfering BSS times the duration of a Tier I CFB, TICFBLength, there will always be such an idle period. The access point sets its timer so that it transmits always right at the end of the CFB sequence. That is, if at time t, an idle of length X(t)>PIFS has been detected, the access point's timer at time t is TXdt−X(t)+PIFS. FIG. 11 illustrates this start-up procedure for a new access point, HC 2 , given an existing access point, HC 1 . Possibility of Collisions Though the backoff delays are set in a deterministic manner, there are no guarantees that collisions will always be avoided. Unless all access points sense the start and end of CFBs at the same time, there is the possibility that interfering BSSs will attempt to access the channel at once. This situation arises when there is significant distance between access points, but not sufficient to eliminate interference between them. Such a situation can be alleviated through the assignment for different channels. Arbitration times are assigned to a centralized access protocol that co-exists with ESTAs accessing the channel through E-DCF. The centralized access protocol has the top priority, while E-DCF can offer traffic classes with priority access both above and below that provided by legacy stations using DCF. Table 1 illustrates the parameter specification for K+1 different classes according to the requirements given above. The centralized access protocol is assigned the highest priority classification, and hence the shortest arbitration time. The top k−1 traffic claws for the E-DCF have priority above legacy but below the centralized access protocol; they achieve differentiation through the variation of the contention window size as well as other parameters. E-DCF traffic classes with priority above legacy have a lower bound, rLower, of the distribution from which backoff values are drawn that is equal to 1 or greater. Differentiation for classes with priority below legacy is achieved by increasing arbitration times; the lower bound of the random backoff distribution can be 0. TABLE 1 TCMA Priority Class Description Priority Class Description Arbitration time rLower 0 Centralized access protocol SIFS >=1 CFBs 1 to k − 1 E-DCF Traffic with priority PIFS = SIFS + 1 >=1 above Legacy or Centralized (slot time) access protocol Tier II CFBs k E-DCF Legacy-equivalent DIFS = SIFS + 2 0 traffic priority (slot time) n = k + 1 E-DCF Traffic priority below >DIFS = SIFS + 0 to K Legacy (2 + n − k) (slot time) BSSs within short interfering range of one another can compete for and share the channel through the use of a deterministic backoff procedure employing post-backoff. Contiguous repeating sequences of contention-free periods provide the centralized protocol efficient access to the channel which is shared by E-DCF transmissions. The relative channel time allotted to the two protocols can be adjusted by tuning parameters of the protocol. Scheduling of traffic queued in multiple queues at the access point can meet QoS requirements. More stringent latency requirements can be met with a two-tiered method, which employs both a timer and post-backoff to initiate CFBs. CFB contiguity is preserved when using deterministic post-backoff or if CFBs of constant length are used whenever transmission is caused by the expiration of the TXdt timer—the Tier I approach. Contiguity is not necessarily preserved, however, if the CFBs have variable length when the Tier I approach is used. Any gaps that would arise in this case would allow contention-based transmissions to be interjected, thus risking delays and possible collisions between HCs. Because of the fixed CFB length requirement, whereas the Tier I approach delivers regularly-spaced CFBs, using it alone, without a Tier II protocol, results in inefficient utilization of the channel. The same fixed bandwidth allocation to each BSS gives rise to situations where channel time allocated for a CFB to one BSS may be left idle while another BSS is overloaded. The Tier II protocols provide for dynamic bandwidth allocation among BSSs. Various illustrative examples of the invention have been described in detail. In addition, however, many modifications and changes can be made to these examples without departing from the nature and spirit of the invention.

A method and system reduce interference between overlapping first and second wireless LAN cells in a medium. Each cell includes a respective plurality of member stations and there is at least one overlapped station occupying both cells. An inter-cell contention-free period value is assigned to a first access point station in the first cell, associated with an accessing order in the medium for member stations in the first and second cells. The access point transmits a beacon packet containing the inter-cell contention-free period value, which is intercepted at the overlapped station. The overlapped station forwards the inter-cell contention-free period value to member stations in the second cell. A second access point in the second cell can then delay transmissions by member stations in the second cell until after the inter-cell contention-free period expires.

BACKGROUND OF THE INVENTION The present invention relates to a sweeping device, and more particularly to a drive for use in such a device for driving a corner-sweeping brush which is mounted in the housing of the sweeping device for rotation about an axis. There are already known various sweeping devices of the type here under discussion, and they are generally used for sweeping floors, carpets or, as the case may be, furniture, upholstery or other surfaces. Such surfaces, more often than not, include corner regions, such as the baseboard regions of a floor where the floor meets with the walls of a room, or similar corner regions next to pieces of furniture or other objects. For the sake of simplicity, the present invention will be described as embodied in a floor-sweeping device, without being restricted thereto. In such a floor-sweeping device, it is already known to provide a housing which carries a dirt-collecting receptacle and at least one main brush which rotates and which deposits the dirt picked up by it from the floor into the receptacle which is to be periodically emptied. It is also already known to provide a drive for such a brush, such drive being often constituted by wheels mounted in the housing and supporting the same during its movement on the floor, a transmission being interposed between these wheels and the brush, which transmits the rotary movement of the wheels to the brush. All this is well known and not part of the present invention. In addition thereto, it is also already known to provide at least one corner-sweeping brush in the front region of the housing of the sweeping device, which corner-sweeping brush may be mounted for rotation about a horizontal or about a vertical axis. Such a corner-sweeping brush may be driven in rotation either by the aforementioned wheels, or by means of an additional wheel or wheels which drive only the corner-sweeping brush. An additional dirt-collecting receptacle may be associated with such a corner-sweeping brush, or the dirt picked-up by the same may be deposited into the shared receptacle either directly by the corner-sweeping brush, or indirectly as a result of the dirt being forwarded by the corner-sweeping brush to the main brush which picks it up and deposits it into the receptacle. A generally satisfactory performance is obtained from such floor-sweeping devices; however, these devices are possessed of a not insignificant drawback; namely, the rotation of the corner-sweeping brush is dependent on the movement of the wheels which drive the same, and thus on the movement of the sweeping device as a whole. As a consequence thereof, when the floor-sweeping device encounters an obstruction, such as upon coming into contact with the baseboard, a base of a piece of furniture, or a similar part preventing further forward movement of the floor-sweeping device, the wheels which drive the corner-sweeping brush come to a standstill, and so does the corner-sweeping brush. As a result of this, imperfect or wholly unsatisfactory sweeping results are obtained in the corner regions of the surface or floor being swept. This, of course, is very disadvantageous, since it is exactly these corner regions where the dirt tends to accumulate and in which the sweeping action ought to be more pronounced than in other regions of the surface. SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to avoid the disadvantages of the prior-art sweeping devices. More particularly, it is an object of the present invention to provide a sweeping device of the above-discussed type which is capable of sweeping the corner regions of a surface being swept. It is a further object of the present invention to devise a drive for rotating the corner-sweeping brush of the sweeping device even after the latter has come to a standstill. It is still another object of the present invention to provide a time-delayed driver for rotating the corner-sweeping brush. In pursuance of these objects, and others which will become apparent hereafter, one feature of the present invention resides, in a sweeping device of the above-discussed type, in the mounting of the corner-sweeping brush in the front region of the housing of the floor-sweeping device as considered in the direction of movement thereof away from the user, and for rotation about an axis. An arrangement is provided for rotating the corner-sweeping brush, which arrangement preferably includes one element rigidly connected with the corner-sweeping brush for shared rotation about the axis of the latter, and another element which is mounted in the housing of the sweeping device for translation between a retracted position and an extended position, and operative for engaging the first-mentioned element during the translation of the other element. An actuating member causes the translation of the other element between the retracted and the extended positions thereof when the front region of the sweeping device reaches an obstruction on a surface being swept, so that the two elements engage one another and cause the corner-sweeping brush to rotate, whereby dirt is removed from the vicinity of the obstruction. The actuating member projects out of the housing of the sweeping device, and is either connected to the handle of the sweeping device, or is independent therefrom and extends either forwardly or upwardly out of the housing. In any event, the actuating member is mounted in the housing for movement in the direction of translation of the other element. As a result of this particular arrangement of the drive for rotating the corner-sweeping brush, it is possible to rotate the corner-sweeping brush even after the housing of the sweeping device has come to a complete standstill upon contacting an obstruction, even though such a corner-sweeping brush would not be otherwise rotating if it were driven by the afore-mentioned wheels. Consequently, provided that the corner-sweeping brush or a plurality of such brushes is so arranged that it reaches forwardly of the housing of the sweeping device, or at least that it is flush with the front surface of the housing, it is possible to sweep the region of the floor immediately adjacent to the obstruction, such a region being henceforth called a corner region. As a result of this, such a corner region can be effectively swept, and the dirt present in such a region can be at least forwarded to the above-mentioned main brush to be picked up by the same and deposited into the dirt-collecting receptacle. Thus, such a sweeping device equipped with the independently driven corner-sweeping brush or brushes is particularly suited for removing dirt from otherwise inaccesible corner regions of the floor, having all the advantages of the conventional sweeping devices as far as removing dirt from other regions of the floor is concerned, but being also operative in the corner regions which were heretofore either totally inaccessible or accessible only to a limited extent to the conventional sweeping devices. In one currently preferred embodiment of the invention, the translation element is mounted in the housing of the sweeping device for movement in the direction of advancement of the latter and tangentially of the rotating element of the arrangement for rotating the corner-sweeping brush, which is connected thereto and coaxial therewith. As a result of this arrangement, it is possible to utilize the force which is in any event exerted by the user of the sweeping device on the same in the advancement direction thereof for driving the corner-sweeping brush into rotation, even though the driving action is accomplished independently of the rotation of the wheels which support the housing. In order to achieve transmission of the force and energy, which is applied by the actuating member to the translation element to the corner-sweeping brush with only a minimum amount of losses, it is proposed according to a further feature of the present invention to construct the rotating element of the arrangement for rotating the brush as a circumferentially toothed pinion, and the translation element as a toothed rack. It is further advantageous according to a further currently preferred embodiment of the present invention to mount the translation element on a thrust rod which extends in the direction of movement of the translation element so as to permit relative displacement between the thrust rod and the translation element in such direction, and to form the translation element with an internal chamber. In this case, a compression spring may be located in the chamber, surrounding the thrust rod and connected at one of its ends, while the other end of the spring engages the translation element. Preferably, the leading end of the spring in the direction of movement of the translation element abuts against a foward transverse wall of the translation element, while the trailing end abuts against a projection of the thrust rod. In this manner, a storage unit is incorporated into the drive for rotating the corner-sweeping brush, which stores the force exerted by the user of the sweeping device and releases the same at a later time. This is due to the fact that the corner-sweeping brush, which is in contact with the surface being swept, is subject to frictional and inertial retardation forces which attempt to prevent the brush from rotating, so that a certain threshold force must be exerted on the brush before it commences its rotation. Thus, the reaction of the corner-sweeping brush to the displacement of the thrust rod is not immediate, but rather a time delay occurs during which the spring is compressed and energy stored therein which is subsequently released with attendant rotation of the brush, even after the forward movement of the housing of the sweeping device, and also that of the thrust rod, have been terminated. It is also proposed, in accordance with a further currently preferred embodiment of the present invention, to provide a control member for controlling the forward movement of the translation element, and particularly for controlling the commencement of the forward movement thereof. Preferably, the control member is constructed as a pawl which has one projection engaging a forwardly facing shoulder of the translation element, and another projection which extends into a recess or slot formed in a lateral wall of the translation element. A further modification of this aspect of the present invention involves the predetermination of the time-delay period, in that the pawl is so configurated that the translation element is arrested in its retracted position until all or at least a substantial part of the available energy has been stored in the spring, depending on the particular configuration of the pawl. Thus, if so desired, the energy available for driving or rotating the corner-sweeping brush can be stored in its entirety in the compression spring, and released only after the sweeping device has completely ceased to move, and the thrust rod has reached its final position. In this manner, the available energy is stored until the corner-sweeping brush is in its final position, in which it has entered to the greatest extent possible into the corner region, and only then the stored energy is fully utilized for rotating the corner-sweeping brush and thus for effectively removing the dirt from the corner region of the floor. In the currently preferred embodiment of the present invention which utilizes the concept of storing most or all of the available energy in the compression spring in the chamber or the translation element, the translation element is formed with a slot which communicates the chamber with the exterior of the translation element, and the projection of the pawl which is received in the slot extends into the chamber and into the path of movement of the projection of the thrust rod against which the compression spring abuts. Preferably, the projection of the pawl which extends into the chamber is formed with an inclined rear surface which comes into contact with the projection of the thrust rod as the latter moves toward its final position, so that subsequently the projection of the thrust rod, as the same advances further, displaces the pawl laterally of the translation element so that the other projection of the pawl which has heretofore engaged the forwardly facing shoulder of the translation element disengages from the same and the translation element is thus automatically released and commences its forward movement into engagement with the pinion, forcing the same to rotate. It is to be understood that the location of the inclined surface of the pawl with respect to the translation member, and the inclination thereof, may be so selected as to predetermine the extent of movement of the thrust member before the translation element is released, and thus to indirectly predetermine the amount of energy stored in the spring prior to such release. A high degree of reliability of function of the control member, and simultaneously a simple construction thereof, result in a currently preferred embodiment of the invention when the control member is mounted in the housing of the sweeping device for pivoting movement in a plane which extends into the path of movement of the translation element, and when a spring is provided which urges the control member toward the translation element. It is also currently preferred that the control member be located at a side of the translation element which faces away from the rotating element of the arrangement for rotating the corner-sweeping brush. In order to insure that the thrust rod and the arrangement for rotating the corner-sweeping brush are returned into their initial positions after the termination of the corner-sweeping operation, there is preferably provided a return spring which is located outside the immediate region of the translation element and which extends between the thrust rod and a wall portion of the housing and urges the thrust rod and, consequently, the elements immediately or indirectly connected thereto, toward their initial positions. In a particularly advantageous embodiment of the present invention, the thrust rod is rigidly connected with a mounting support for a handle of the sweeping device, which mounting support is mounted in the housing of the sweeping device for a limited displacement in the direction of advancement of the sweeping device and thus of the thrust rod. In this manner, it is achieved that, when the sweeping device comes to a sudden stop upon abutting against an obstruction, the continuing movement of the handle and thus of the mounting support thereof in the forward direction of the sweeping device results in a corresponding movement of the thrust rod and, eventually, in a movement of the translation member into driving engagement with the rotating element of the drive for the corner-sweeping brush, which movement is terminated only after the thrust rod has reached its final position. However, it is also possible, in a modified embodiment of the present invention, to so arrange the thrust rod associated with the particular corner-sweeping brush that it projects frontwardly of the sweeping device, and to possibly provide the projecting end of the thrust rod with an enlarged head portion. In this modified embodiment, the thrust rod will be displaced toward its final position even before the housing proper of the sweeping device has reached its final position adjacent the obstruction. It will be appreciated that the time-delay feature of the present invention is particularly important in this modified embodiment. In all other respects, the configuration and function of the drive for driving the corner-sweeping brush are identical with the above-discussed embodiment, except that the thrust rod remains stationary and the rest of the sweeping device moves with respect to the thrust rod. According to a further modified embodiment of the present invention, it is also possible to construct the drive for rotating the corner-sweeping brush as a worm gear assembly, wherein a rotating element is associated with the corner-sweeping brush, and the translation element is coaxial with the rotating element. In this embodiment, the thrust rod may extend upwardly of the housing of the sweeping device so that, after the sweeping device has reached its final position next to the obstruction, the thrust rod may be actuated by the user of the sweeping device, either manually or by stepping on the free end of the thrust rod which may again be provided with an enlarged head portion. In a currently preferred embodiment of this modification, the main axes of the drive elements coincide with the axis of rotation of the corner-sweeping brush, forming extensions thereof, which results in a particularly simple construction of the drive. While it is currently preferred that the thrust rod itself extends upwardly of the housing, it is also possible to have separate actuating means, in which event the thrust rod may be fully accommodated within the housing. In order to assure proper and reliable functioning of the drive, it is further proposed that the translation element of this drive be provided with a guiding projection, and that the housing of the sweeping device be provided with a guiding channel receiving the guiding projection of the translation element, and to provide a compression spring between the housing and the translation element which urges the latter toward its initial position. The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing. BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of a floor-sweeping device having two corner-sweeping brushes driven in accordance with the present invention; FIG. 2 is a partial cross-sectional view of a first embodiment of the drive for the corner-sweeping brush according to the invention; FIG. 3 is a partial cross-sectional view of a second embodiment of the drive for the corner-sweeping brush according to the invention; and FIG. 4 is a partial cross-sectional view of a third embodiment of the drive for the corner-sweeping brush according to the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, and first to FIG. 1 thereof, it may be seen therein that the drive according to the present invention is to be used in an otherwise conventional floor-sweeping device which includes a housing 10, in which there is mounted, in a conventional manner, a brush roller or a plurality of such brush rollers which are well known and thus have not been illustrated. It suffices to say that such rollers pick up the dirt from the surface being swept, and that they deposit the dirt into one or more receptacles in the housing. The brush rollers may be driven into rotation by means of wheels which engage the surface being swept and whose movement, as the housing 10 is displaced, is transmitted to the brush rollers. These wheels are also conventional so that they also need not be illustrated. In addition thereto, the otherwise conventional sweeping device is equipped with corner-sweeping brushes 12, which in the illustrated example are cup-shaped and the bristles thereof extend forwardly and laterally beyond the circumference of the housing 10. Of course, the brushes 12 could also be configurated as brush rollers mounted for rotation about a horizontal axis. The purpose of the corner-sweeping brushes 12 is to remove the dirt from the regions of the surface being swept which are not accessible to the main brushes or brush rollers, and to forward the dirt into a collecting receptacle either directly or indirectly by forwarding the dirt into regions spaced from the corner regions to which the main brushes have access and from which they are capable of picking up the dirt and of forwarding the same into the collecting receptacle. It is to be understood that the present invention is not limited to the type of corner-sweeping brushes which is shown in the drawing, or to the particular described operation thereof. The sweeping device is provided with a handle 13 which has a free end portion to be grasped by the user of the device, and a bifurcated end portion 14 having two extensions 15 which embrace the housing 10. Push-pull movements transmitted to this handle 13 by a user result in corresponding movements of the housing 10. The extensions 15 have end portions which extend at angles to the extensions 15 and reach into the housing 10 where they are pivoted for movement about an axis which extends transversely of the housing 10. Having so described the general environment in which the drive for the corner-sweeping brush 12 is utilized, attention will now be directed to the embodiment of the present invention illustrated in FIG. 2. It is to be noted that the corner-sweeping brush 12 of this embodiment is mounted in the housing 10 for rotation about an upright shaft 16, that is a shaft having an axis which extends substantially normal to the surface being swept, so that the cup-shaped bristle annulus of the brush 12 contacts the surface being swept in its front region. A rotating element, shown as a pinion 17, is rigidly connected to the shaft 16 to share its rotation about its axis, and the pinion 17 constitutes one part of the drive for rotating the corner-sweeping brush 12 independently of the movement of the aforementioned wheels. A translation element, configurated as a toothed rack 18, is located adjacent to the pinion 17 which is rigidly connected to the brush 12, and constitutes another part of the drive. The sweeping device housing 10 is formed with a guide 19 which extends in the direction of advancement of the housing 10, and the translation element 18 is mounted in the guide 19 for movement longitudinally thereof between a retracted position and an extended position. A thrust rod 20 extends longitudinally of the guide 19 and through the translation element 18, and is mounted in the housing 10 for movement in the same direction as, but independently of, the translation element 18, so that the translation element 18 may assume different positions with respect to the thrust rod 20. The translation element 18 is formed with a chamber 21, and a compression spring 22 is accommodated in the chamber 21, surrounding the thrust rod 20. The translation element 18 is further formed with a front transverse wall 23, and the thrust rod 20 is provided with a flange-shaped projection 24, and the spring 22 extends between and abuts the front transverse wall 23, on the one hand, and the projection 24, urging the same away from one another. A control member 25 is mounted in the housing 10 for pivoting movement in a plane which extends into the guide 19 and longitudinally thereof. The control member 25 is located to a side of the translation element 18 which faces away from the rotating element 17, that is to a side of the element 18 which is not provided with the teeth. The control member 25 includes an arresting projection 26 which, when the translation element 18 is in its initial or retracted position shown in the drawing, engages the adjacent front region of the transverse wall 23 of the translation element 18, so that it prevents the translation element 18 from moving toward its extended position. In addition thereto, the control member 25 is provided with another projection 27 which reaches into a slot 28 provided in the adjacent lateral wall 29 of the translation element 18, and extends into the chamber 21 and into the path of movement of the flange-shaped projection 24 of the thrust rod 20. A spring 30 presses against the control member 25 and urges the same in the direction of engagement thereof with the translation element 18, that is toward the position illustrated in FIG. 2. Rearwardly of the translation element 18 when considered in direction of movement thereof toward the extended position, the thrust rod 20 extends through an opening 31 formed in a transverse wall 32 of the housing 10 which limits the guide 19 and thus determines the retracted position of the translation element 18, and is rigidly connected with a mounting support 33 to which the bifurcated portion 14 of the handle 13 is in turn connected. The mounting support 33 is in turn mounted in wall openings 34 of the housing 10 of the sweeping device for sliding movement therein. In the illustrated embodiment, the thrust rod 20 extends beyond the mounting support 33 and through a guide opening 35 provided in an additional transverse wall 36 of the housing 10. Finally, it is to be mentioned that the mounting support 33, and thus the thrust rod 20, are acted upon by a return spring 37, which urges the thrust rod 20 and the other parts which are directly or indirectly connected thereto, toward their initial positions. When the sweeping device reaches an obstruction during its forward movement, so that the front region of the housing 10 contacts the obstruction, the further progress of the sweeping device terminates. However, at the same time, due to the mounting of the mounting support 33 in the wall openings 34 for sliding movement therein in the direction of advancement of the sweeping device, and due to the fact that a force is still exerted by the user of the sweeping device on the handle 13 and thus on the mounting support 33, the latter is displaced from its initial position toward the front region of the housing 10. When the bifurcated end portion 14 of the handle 13, and thus the mounting support 33 in which the latter is mounted for pivoting movement about an axis, are displaced forwardly of the housing 10, the thrust rod 20 is displaced in the same direction, that is forwardly of the housing 10; initially, the translation element 18 remains stationary, so that the thrust rod 20 is displaced relative to the translation element 18 and the spring 22 is compressed. However, as soon as the projection 24 of the thrust rod 20 comes into contact with the projection 27 of the control member 25, the latter is displaced outwardly against the action of the spring 30, so that eventually the projection 26 of the control member 25 is displaced to such an extent that it releases the translation element 18. Thus, the displacement of the translation element 18 follows that of the thrust rod 20 only after a certain, predetermined period of time, so that the thrust rod 20 with its projection 24, the translation member 18, the spring 30 and the control member 25 form a time-delay unit. Once the translation element 18 is released, engagement is established between the same and the pinion 17, and the further movement of the translation element 18 toward its extended position results in the rotation of the pinion 17 and thus of the corner-sweeping brush 12. The extent of the displacement of the thrust rod 20 is limited by the length of the wall openings 34 for the mounting support 33 connected to the bifurcated portion 14 of the handle 13, so that the extent of movement of the translation element 18 is similarly limited to movement between an initial, or retracted position, and a final, or extended position. Since the forward or front portion of the corner-sweeping brush 12 contacts the surface being swept, the rotation of the brush 12 results in removal of the dirt from the corner region adjacent to the obstruction and in forwarding of the same toward the rear of the sweeping device, that is either into a separate dirt-collecting receptacle (not shown), or toward the main brush (also not shown) which picks up the dirt forwarded to it by the action of the corner-sweeping brush 12 and deposits it into a dirt-collecting receptacle associated with the main brush and well known in the art. The embodiment of the present invention which is illustrated in FIG. 3 is in many respects similar to that discussed previously, and thus the same reference numerals have been used to designate corresponding parts of this embodiment. The main difference between this and the previous embodiment resides in the fact that the thrust rod 20 is not connected to the handle 13 of the sweeping device, but rather projects frontwardly out of the housing 10. The free end portion of the thrust rod is provided with an enlarged head portion 38. Also, the arrangement of the thrust rod 20 and of the translation element 18 is so changed with respect to the previously discussed embodiment that the associated parts are rotated with respect to the pinion 17 by 180° about a vertical axis. In this embodiment of the present invention, the thrust rod 20, when the housing 10 of the sweeping device approaches an obstruction so that the head portion 38 abuts the same, is displaced relative to the housing 10 against the action of a return spring 37 and also against the action of the spring 22 toward the rear of the housing 10. As a matter of fact, relative to the environment, the movement of the thrust rod 20 is arrested while the housing 10 of the sweeping device continues its forward movement, but the result is the same as in the housing 10 were stationary and the thrust rod 20 moved with respect thereto. As soon as the projection 24 of the thrust rod 20, which also serves as an abutment for the spring 22 accommodated in the chamber 21 of the translation element 18, contacts the projection 27 of the control member 25 which extends into the chamber 21 and into the path of movement of the projection 24, the control member 25 is displaced outwardly with respect to the translation element 18 against the action of the spring 30 and into an inactive position. As soon as the control member 25 releases the translation element 18, and from then on, the latter commences its displacement in the direction of the displacement of the thrust rod 20 and toward its extended position as a result of the action of the spring 22 which had previously accumulated energy therein. The displacement of the translation element 22 again follows that of the thrust rod 20 after a time delay which depends on the particular construction of the time-delay unit encompassing the spring 22, the control member 25, the translation element 18 and the thrust rod 20. Following the release of the translation element 18, the latter engages the pinion 17 and subsequently drives the same and thus the corner-sweeping brush 12 into rotation, so that dirt is forwarded from the corner region adjacent the obstruction toward the center of the sweeping device. A further embodiment of the present invention is illustrated in FIG. 4. In this embodiment, the actuation of the corner-sweeping brush 12 is independent of the respective position of the sweeping device, that is, the corner-sweeping brush can be actuated irrespective of whether or not an obstruction has been encountered. Thus, while the brush 12 will be mostly actuated only in the corner regions of the surface being swept, it can also be actuated in other regions of the surface, such as excessively soiled regions of the surface. In this embodiment, the brush 12 is mounted in the housing 10 of the sweeping device for rotation about an upright shaft 40, that is a shaft whose axis again extends substantially normal to the surface being swept. The shaft 40 is supported in a bearing block 41, and it is rigidly connected with a driving spindle 42 upwardly of the bearing block 41. A driving nut 43 is mounted in the housing 10 for translation coaxially with the spindle 42. In this embodiment, the spindle 42 constitutes the rotating element, and the nut 43 the translation element, of the drive for the brush 12. The nut 43 is formed with an extension 44 which projects upwardly out of the housing 10, and an enlarged head portion 45 is provided on the extension 44 and of the housing 10. A return spring 46 acts on the nut 43, urging the same toward the position illustrated in FIG. 3, and the housing 10 is formed with a guide slot 48 into which a guide projection 47 of the nut 43 projects, the cooperation of the projection 47 with the slots 48 resulting in only translational movement of the nut 43, without any rotation thereof. The spindle 42 and the nut 43 are formed with complementary worm gears. Of course, the nut 43 could also be connected to the shaft 40, and the spindle 42 to the extension 44, without any change in the overall design and operation of the drive for the brush 12. When the brush 12 is to be actuated, for instance in a corner region of the surface being swept, the extension 44 is displaced downwardly, for instance by the user's stepping on the enlarged portion 45, so that the nut 43 (or the spindle 42, as the case may be), is also displaced downwardly, so that the complementary gears of the spindle 42 and of the nut 43 engage one another and cause the shaft 40 of the brush 12 to rotate. As a result of the direct connection of the spindle 42 (or the nut 43) with the shaft 40, the brush 12 can be rotated independently of the movement of the sweeping device, that is even if the latter is stationary. As already mentioned, the above-discussed embodiments are only illustrative of the concept of the present invention, and the latter is not limited to the discussed and illustrated embodiments. So, for instance, the brush 12 may be of a different configuration and/or arrangement in the housing 10, in which a similar drive arrangement may be utilized after being modified to comply with the particular requirements. Also, the time-delay feature may be omitted, in which case the translation element 18 will be directly connected to or of one piece with the thrust rod 20. In addition thereto, other arrangements may be provided for driving the brush 12 also during the normal operation of the sweeping device, that is outside of the corner regions of the surface being swept, and for discontinuing the operation of such driving arrangements when the sweeping device reaches a corner region, at which time the drive according to the present invention takes over. It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of sweeping devices differing from the types described above. While the invention has been illustrated and described as embodied in a sweeping device for sweeping floors, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

A drive for rotating a corner-sweeping brush of a sweeping device includes a gear on the brush, and a translation member provided with teeth engaging the gear and rotating the same about its axis with attendant rotation of the brush when the housing of the sweeping device comes into contact with an obstruction during its forward movement. An actuating member is connected to the translation member under interposition of a time-delay unit, and moves the translation member into engagement with the gear and subsequently toward an extended position thereof with concomitant rotation of the brush so that dirt is removed from the corner region of the surface being swept, even after the housing of the sweeping device has come to a standstill. The actuating member may be connected to a handle of the sweeping device, or it may be a discrete element projecting forwardly or upwardly out of the housing.

BACKGROUND/SUMMARY [0001] Carbonaceous soot may be a bi-product of some combustion processes. For example, carbonaceous soot may be produced by some diesel engines during higher engine load conditions. More recently, gasoline engines have incorporated directly injecting fuel into engine cylinders to improve engine performance and fuel economy. However, directly injecting fuel to engine cylinders has also increased the possibility of producing carbonaceous soot in gasoline engines. As a result, some manufacturers are considering placing particulate filters within the exhaust systems of gasoline engines. [0002] Particulate filters can hold carbonaceous soot, but over time, the soot accumulated within the particulate filter can reduce exhaust flow through the exhaust system. Consequently, engine back pressure may increase, thereby reducing engine efficiency and fuel economy. Buildup of soot within the particulate filter can be controlled by periodically oxidizing the soot. Soot trapped in a particulate filter can be oxidized by elevating the temperature of engine exhaust gas flowing into the particulate filter and providing excess oxygen for oxidation. However, elevating engine exhaust temperatures may reduce engine fuel economy since the engine may be operated less efficiently to increase exhaust gas temperatures. Therefore, it may be desirable to limit soot purging or regeneration of the particulate filter to conditions where the particulate filter holds an amount of soot that warrants oxidation. [0003] One way to determine whether or not timing is desirable for oxidizing soot held within a particulate filter requires measuring exhaust pressure upstream and downstream of the particulate filter. If a pressure difference greater than a threshold amount develops between the upstream and downstream pressure measurements, it is determined that there is sufficient soot mass for the oxidation process. Although determining a pressure difference within the exhaust system may be possible, adding pressure sensors to the exhaust system raises system cost. In addition, pressure sensors may not be as durable in the exhaust system as compared to other types of sensors. [0004] The inventor here has recognized the above-mentioned disadvantages and has developed a method for determining operating a particulate filter, comprising: estimating soot mass oxidized from a particulate filter via first and second oxygen sensors; and indicating degradation of the particulate filter when a difference between the estimated soot mass oxidized from the particulate filter and a desired soot mass held in the particulate filter is greater than a threshold soot mass. [0005] A mass of soot oxidized within a particulate filter can be determined in response to output of oxygen sensors. In one example, a mass of soot oxidized in a particulate filter is determined from an amount of oxygen that is consumed during soot oxidation. Oxygen sensors are typically included in the exhaust systems of gasoline engines to improve air-fuel control and three-way catalyst efficiency. Thus, a mass of soot held within a particulate filter may be determined via oxygen sensors that are in the engine exhaust for determining engine air-fuel control. Consequently, cost for a system to control particulate filter soot can be reduced since oxygen sensors can be used for more than a single purpose. [0006] The present description may provide several advantages. In particular, the approach can reduce particulate filter system cost since oxygen sensors determine a mass of soot within a particulate filter rather than pressure sensors. In addition, particulate filter leakage may be determined with the approach. Further, the approach compensates for differences in oxygen sensor output to improve stored soot estimates whereas output of pressure sensors and particulate sensors may be influenced by the presence of the particulate filter. [0007] The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings. [0008] It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. BRIEF DESCRIPTION OF THE FIGURES [0009] FIG. 1 shows a schematic depiction of an engine; [0010] FIG. 2 shows signals of interest during oxidation of soot from a particulate filter; [0011] FIGS. 3-5 show high level flowcharts of methods for determining soot mass oxidized within a particulate filter and particulate filter leakage. DETAILED DESCRIPTION [0012] The present description is directed to determining a soot mass oxidized within a particulate filter. FIG. 1 shows one example embodiment for a system that includes a particulate filter. The system includes spark ignition engine that may be operated with gasoline, alcohol, or a mixture of gasoline and alcohol. FIG. 2 shows prophetic signals of interest for a system that estimates soot mass with oxygen sensors. The signals may be realized with the system of FIG. 1 executing the methods of FIGS. 3-5 . [0013] Referring to FIG. 1 , internal combustion engine 10 , comprising a plurality of cylinders, one cylinder of which is shown in FIG. 1 , is controlled by electronic engine controller 12 . Engine 10 includes combustion chamber 30 and cylinder walls 32 with piston 36 positioned therein and connected to crankshaft 40 . Combustion chamber 30 is shown communicating with intake manifold 44 and exhaust manifold 48 via respective intake valve 52 and exhaust valve 54 . Each intake and exhaust valve may be operated by an intake cam 51 and an exhaust cam 53 . Alternatively, one or more of the intake and exhaust valves may be operated by an electromechanically controlled valve coil and armature assembly. The position of intake cam 51 may be determined by intake cam sensor 55 . The position of exhaust cam 53 may be determined by exhaust cam sensor 57 . [0014] Fuel injector 66 is shown positioned to inject fuel directly into cylinder 30 , which is known to those skilled in the art as direct injection. Alternatively, fuel may be injected to an intake port, which is known to those skilled in the art as port injection. Fuel injector 66 delivers liquid fuel in proportion to the pulse width of signal FPW from controller 12 . Fuel is delivered to fuel injector 66 by a fuel system (not shown) including a fuel tank, fuel pump, and fuel rail (not shown). Fuel injector 66 is supplied operating current from driver 68 which responds to controller 12 . In addition, intake manifold 44 is shown communicating with optional electronic throttle 62 which adjusts a position of throttle plate 64 to control air flow from intake boost chamber 46 . [0015] Exhaust gases spin turbine 164 which is coupled to compressor 162 via shaft 161 . Compressor 162 draws air from air intake 42 to supply boost chamber 46 . Thus, air pressure in intake manifold 44 may be elevated to a pressure greater than atmospheric pressure. Consequently, engine 10 may output more power than a normally aspirated engine. [0016] Distributorless ignition system 88 provides an ignition spark to combustion chamber 30 via spark plug 92 in response to controller 12 . Ignition system 88 may provide a single or multiple sparks to each cylinder during each cylinder cycle. Further, the timing of spark provided via ignition system 88 may be advanced or retarded relative to crankshaft timing in response to engine operating conditions. [0017] Universal Exhaust Gas Oxygen (UEGO) sensor 126 is shown coupled to exhaust manifold 48 upstream of exhaust gas after treatment device 70 . Alternatively, a two-state exhaust gas oxygen sensor may be substituted for UEGO sensor 126 . The engine exhaust system includes a second exhaust gas after treatment device 72 located downstream (e.g., in the direction of exhaust flow) of exhaust gas after treatment device 70 . The exhaust system also contains universal oxygen sensors 127 and 128 . In some examples, exhaust gas after treatment device 70 is a particulate filter and exhaust gas after treatment device 72 is a three-way catalyst. In other examples, exhaust gas after treatment device 70 is a three-way catalyst and exhaust gas after treatment device 72 is a particulate filter. In still further examples, a third exhaust gas after treatment device comprising a three-way catalyst may be positioned downstream of the second exhaust gas after treatment device. [0018] Controller 12 is shown in FIG. 1 as a conventional microcomputer including: microprocessor unit 102 , input/output ports 104 , read-only memory 106 , random access memory 108 , keep alive memory 110 , and a conventional data bus. Controller 12 is shown receiving various signals from sensors coupled to engine 10 , in addition to those signals previously discussed, including: engine coolant temperature (ECT) from temperature sensor 112 coupled to cooling sleeve 114 ; a position sensor 134 coupled to an accelerator pedal 130 for sensing accelerator position adjusted by foot 132 ; a knock sensor for determining ignition of end gases (not shown); a measurement of engine manifold pressure (MAP) from pressure sensor 121 coupled to intake manifold 44 ; a measurement of boost pressure from pressure sensor 122 coupled to boost chamber 46 ; an engine position sensor from a Hall effect sensor 118 sensing crankshaft 40 position; a measurement of air mass entering the engine from sensor 120 (e.g., a hot wire air flow meter); and a measurement of throttle position from sensor 58 . Barometric pressure may also be sensed (sensor not shown) for processing by controller 12 . In a preferred aspect of the present description, engine position sensor 118 produces a predetermined number of equally spaced pulses every revolution of the crankshaft from which engine speed (RPM) can be determined. [0019] In some embodiments, the engine may be coupled to an electric motor/battery system in a hybrid vehicle. The hybrid vehicle may have a parallel configuration, series configuration, or variation or combinations thereof. Further, in some embodiments, other engine configurations may be employed, for example a diesel engine. [0020] During operation, each cylinder within engine 10 typically undergoes a four stroke cycle: the cycle includes the intake stroke, compression stroke, expansion stroke, and exhaust stroke. During the intake stroke, generally, the exhaust valve 54 closes and intake valve 52 opens. Air is introduced into combustion chamber 30 via intake manifold 44 , and piston 36 moves to the bottom of the cylinder so as to increase the volume within combustion chamber 30 . The position at which piston 36 is near the bottom of the cylinder and at the end of its stroke (e.g. when combustion chamber 30 is at its largest volume) is typically referred to by those of skill in the art as bottom dead center (BDC). During the compression stroke, intake valve 52 and exhaust valve 54 are closed. Piston 36 moves toward the cylinder head so as to compress the air within combustion chamber 30 . The point at which piston 36 is at the end of its stroke and closest to the cylinder head (e.g. when combustion chamber 30 is at its smallest volume) is typically referred to by those of skill in the art as top dead center (TDC). In a process hereinafter referred to as injection, fuel is introduced into the combustion chamber. In a process hereinafter referred to as ignition, the injected fuel is ignited by known ignition means such as spark plug 92 , resulting in combustion. During the expansion stroke, the expanding gases push piston 36 back to BDC. Crankshaft 40 converts piston movement into a rotational torque of the rotary shaft. Finally, during the exhaust stroke, the exhaust valve 54 opens to release the combusted air-fuel mixture to exhaust manifold 48 and the piston returns to TDC. Note that the above is described merely as an example, and that intake and exhaust valve opening and/or closing timings may vary, such as to provide positive or negative valve overlap, late intake valve closing, or various other examples. [0021] Referring now to FIG. 2 , prophetic signals of interest during oxidation of soot from a particulate filter are shown. The signals may be provided by the system of FIG. 1 executing the methods of FIGS. 3-5 . Five plots are shown relative to time, and each plot occurs at the same time as the other plots. Vertical markers T 0 -T 3 indicate times of particular interest. [0022] The first plot from the top of the figure shows engine air-fuel versus time. Horizontal marker 202 represents an oxygen concentration of stoichiometric air-fuel combusted by an engine. The engine air-fuel ratio moves leaner in the direction of the Y axis arrow. The engine air-fuel ration moves richer in the direction of the bottom of the first plot. The X axis represents time, and time increases from the left to the right. [0023] The second plot from the top of the figure shows engine exhaust gas oxygen concentration as measured via an oxygen sensor at a location in an exhaust system upstream of an inlet of a particulate filter (PF). In this example, the oxygen concentration upstream of the inlet of the particulate filter follows the engine air-fuel ratio since there is no three-way catalyst positioned upstream of the particulate filter. In examples where a three-way catalyst is located upstream of the particulate filter, the oxygen concentration may exhibit a more filtered response since the three-way catalyst may use some exhaust gas oxygen to oxidize combustion bi-products. The concentration of exhaust gas oxygen increases in the direction of the Y axis and decreases in a direction of the bottom of the plot. The X axis represents time, and time increases from the left to the right. [0024] The third plot from the top of the figure shows engine exhaust gas oxygen concentration as measured via an oxygen sensor at a location in an exhaust system downstream of an inlet of a particulate filter (PF). The concentration of exhaust gas oxygen increases in the direction of the Y axis and decreases in a direction of the bottom of the plot. The X axis represents time, and time increases from the left to the right. [0025] The fourth plot from the top of the figure represents an amount of particulate matter (e.g., soot mass) estimated to be held within a particulate filter. In one example, the amount of particulate matter may be estimated based on engine speed, engine torque, engine fuel timing, and engine spark timing. In particular, empirical data stored in functions or tables may be indexed via engine speed, engine torque, engine fuel timing, and engine spark timing to output a mass flow rate of particulate matter. The mass flow rate of soot may be integrated over time to estimate soot mass held within the particulate trap. In some examples, the mass flow rate of soot from the engine may be multiplied by a filtering efficiency for the particulate filter to determine soot mass held within the particulate filter. The filtering efficiency may be estimated by indexing empirically determined filtering efficiencies that are indexed with filter temperature, filter mass flow rate, and soot flow rate. The soot mass held within the particulate filter increases in the direction of the Y axis. The X axis represents time, and time increases from the left to right. Horizontal marker 204 represents soot mass where it is desirable to oxidize soot held within the particulate filter. [0026] The fifth plot from the top of the figure represents a control signal that initiates and ends a soot oxidation sequence. Soot oxidation is not commanded when the oxidation command is at a low level (e.g., near the bottom of the plot). Soot oxidation is commanded when the oxidation command is at a high level (e.g., near the top of the plot). The X axis represents time, and time increases from the left to the right. [0027] At time T 0 , the engine air-fuel is controlled around stoichiometric conditions so that exhaust gas conditions at a downstream three-way catalyst are also near stoichiometric conditions. The conversion efficiencies of the three-way catalyst are high when operated around stoichiometry. The upstream or pre particulate filter oxygen concentration follows the engine air fuel ratio signal since the exhaust gas oxygen concentration is related to engine air-fuel ratio. Further, the soot mass held within the particulate filter is less than the soot mass where it may be desirable to oxidize soot held within the particulate filter. Consequently, the particulate filter oxidation command is set at a low level so that operating conditions are not adjusted to accommodate oxidation of soot at the particulate filter. For example, the temperature of the particulate filter is not adjusted to a level where soot may be oxidized at the particulate filter. [0028] At time T 1 , the engine air-fuel ratio remains moving about stoichiometric conditions so that high efficiency of the downstream three-way catalyst is maintained. Further, the exhaust gas oxygen concentration as determined from an oxygen sensor located upstream of the particulate filter continues to follow a trajectory similar to the engine air-fuel ratio. The exhaust gas oxygen concentration as determined from an oxygen sensor located downstream of the particulate filter also continues to follow a trajectory similar to the engine air-fuel ratio. However, the estimated soot mass reaches soot mass level 204 which initiates a particulate filter soot oxidation process. Accordingly, the particulate filter oxidation command signal transitions to a high state at T 1 . [0029] Engine operating conditions may be adjusted when the particulate filter oxidation command signal is transitioned to a high state. For example, spark timing can be retarded and engine mass air flow increased so that conditions at the particulate filter may be more conducive for oxidation of soot held by the filter. In other examples, fuel injection timing may also be adjusted. [0030] At time T 2 , the engine air-fuel ratio and the exhaust gas oxygen concentration as determined from an oxygen sensor located upstream of the particulate filter continue to vary around stoichiometric conditions. However, the exhaust gas oxygen concentration as determined from an oxygen sensor located downstream of the particulate filter begins to attenuate as the particulate filter reaches a temperature conducive for oxidation of soot held within the particulate filter. Further, the estimated soot mass oxidized from the particulate filter may be updated as the soot mass oxidized is determined as is shown. Thus, in some examples the soot mass is stepped down as soot is oxidized in the trap as determined from the upstream and downstream oxygen sensors. The particulate filter oxidation command remains at a high level at time T 3 . [0031] Between times T 2 and T 3 , the engine air-fuel ratio is modulated around stoichiometric conditions. For example, during a first portion of a time period, the engine air-fuel ratio is rich. During a second portion of a time period, the engine air-fuel is lean. However, the engine air-fuel is leaned to a greater extent as compared to when the engine was operated before time T 2 . The engine air-fuel ratio is further leaned so that when the exhaust gases exit the particulate filter after oxidizing a portion of soot within the particulate filter, an exhaust gas mixture, on average, indicative of stoichiometric combustion enters the three-way catalyst located downstream of the particulate filter. [0032] In other examples, additional air may be added to the exhaust system via an air pump or other device to increase the level of oxygen that enters the particulate filter so that excess oxygen is available to the three-way catalyst located downstream of the particulate filter. In examples where air is added to the exhaust system, the air can be periodically pulsed in response to oxygen entering and exiting the three-way catalyst. [0033] The engine air-fuel ratio frequency of oscillation is shown being varied as is the duty cycle and the lean portion of the engine air-fuel ratio. The frequency of oscillation and the duty cycle of the engine air-fuel ratio may be adjusted in response to an estimated amount of oxygen stored within the catalyst and an estimated consumption rate of reductantants. For example, the lean portion of an engine air-fuel ratio cycle can be adjusted to a first amplitude when a soot mass estimated to be stored in a particulate filter is a first amount. The lean portion of the engine air-fuel cycle can be adjusted to a second amplitude when the soot mass estimated to be stored in the particulate filter is a second amount, the second amplitude less than the first amplitude (e.g., second amplitude richer than the first amplitude) when the first amount is greater than the second amount. [0034] In some examples, the frequency, duty cycle, and amplitude of the lean portion of the engine air-fuel ratio is stored in controller memory and indexed via engine speed and engine load. However, if more or less oxygen than is expected exits the particulate filter, the duty cycle, frequency, and amplitude of the engine air-fuel ratio can be adjusted so that near stoichiometric exhaust gases are delivered to the downstream three-way catalyst. [0035] In addition, as shown in FIG. 2 , the lean amplitude, duty cycle, and frequency of the engine air-fuel ratio are adjusted in response to soot oxidized within the particulate filter as observed by a oxygen sensor located downstream of the particulate filter. For example, if excess oxygen beyond what is desired for the three-way catalyst located downstream of the particulate filter, the lean amplitude of the engine air-fuel ratio is decreased to richen the engine air-fuel ratio cycle. In another example, the lean amplitude, frequency of oscillation, and duty cycle of the engine air-fuel ratio are adjusted automatically as the controller determines that the soot mass oxidized approaches the soot mass held within the particulate filter. For example, each time the soot mass of the soot held within the particulate filter is lowered due to oxidation, the lean amplitude is decreased, the duty cycle is adjusted to reduce the lean portion of the engine air-fuel cycle, and the frequency may be decreased as well. Air entering the particulate filter from external the engine may be adjusted in a similar manner. [0036] At time T 3 , the particulate filter oxidation command is reset to a low level. The particulate filter oxidation command may be reset to a low level when a mass of air exiting the particulate filter is greater than expected after the lean amplitude of the air-fuel ratio has been decreased. In another example, the particulate filter oxidation command may be reset when the determined oxidized soot mass is greater than at threshold amount, seventy five percent of the estimated stored soot mass for example. The oxidized soot mass during such operation is determined from oxygen sensors positioned upstream and downstream of the particulate filter as described in the methods of FIGS. 3-5 . Engine operating conditions are returned to operating conditions for fuel economy, emissions, and drivability after the particulate filter oxidation command is commanded off. Thus, spark can be advanced and engine air mass may be reduced in response to the particulate filter oxidation command being commanded off. [0037] Referring now to FIG. 3 , a method for determining soot mass oxidized within a particulate filter and particulate filter leakage is shown. The method of FIG. 3 is executable via instructions of controller 12 within the system of FIG. 1 . [0038] At 302 , method 300 determines engine operating conditions. In one example, engine operating conditions include but are not limited to engine speed, engine load, exhaust gas oxygen concentration as measured from a plurality of locations in the engine exhaust system, engine coolant temperature, engine air amount, and fuel injection timing. Method 300 proceeds to 304 after engine operating conditions are determined. [0039] At 304 , method 300 estimates the soot mass stored within a particulate filter of the exhaust system. In one example, method 300 estimates the soot mass within the particulate filter from engine operating conditions including the amount of time the engine operated at the operating conditions. For example, engine air mass or engine load along with engine speed may be used to index a table that holds empirically determined soot mass flow rates. The soot mass flow rates may be integrated over time to estimate the amount of soot mass held within the particulate filter. In some examples, particulate filter efficiency may similarly be determined from a table that holds empirically determined particulate filter efficiencies. [0040] At 306 , method 300 judges whether or not to combust soot held within a particulate filter. If the soot mass within the particulate filter exceeds a predetermined amount, method 300 proceeds to 306 . Otherwise, method 300 proceeds to exit. It should be noted that method 300 may exit or bypass the particulate filter combustion process in response to operating conditions other than soot mass held within the particulate filter. For example, method 300 may exit when a temperature of the particulate filter exceeds a predetermined threshold. In another example, method 300 exits in response to an operator requesting a torque that is greater than a predetermined value, or if exhaust pressure is greater than a predetermined value during combustion of the particulate filter soot mass. [0041] At 308 , method 300 elevates the temperature of the particulate filter. In one example, the particulate filter is elevated via increasing spark retard and engine air-flow rate. For example, spark may be retarded by a predetermined amount from base spark timing. Further, the engine air-flow can be increased so that the engine produces an equivalent amount of torque even while spark is retarded and while exhaust gas temperatures increase. In some examples, the exhaust gas temperature may be estimated from engine speed, engine air mass, and spark advance. Method 300 proceeds to 310 after particulate filter temperature is raised. [0042] At 310 , method 300 judges whether or not the particulate filter is at a desired temperature to facilitate combustion of soot mass held within the particulate filter. If so, method 300 proceeds to 312 . Otherwise, method 300 returns to 308 where additional actions may be taken to increase particulate filter temperature. For example, additional spark retard may be provided. [0043] At 312 , method 300 delivers a lean exhaust gas mixture to the particulate filter. In one example, the method of FIG. 4 provides a lean exhaust gas mixture. However, other methods may be employed in the alternative. Method 300 proceeds to 314 after a lean exhaust gas mixture is provided to the inlet of the particulate filter. [0044] At 314 , method 300 determines a soot mass stored within a particulate filter. In one example, the method of FIG. 5 determines the soot mass held within a particulate filter from oxygen sensors position in an exhaust system upstream and downstream of a particulate filter. In particular, the soot mass oxidized within a particulate filter is determined at least partially in response to a difference of oxygen concentration between two oxygen sensors. Method 300 proceeds to 316 after determining the soot mass oxidized from a particulate filter. [0045] At 316 , method determines whether a desired amount of soot was stored within the particulate filter. In one example, the soot mass determined at 314 is subtracted from the soot mass estimated at 304 . If it has been determined that soot has been substantially removed from the particulate filter during the soot oxidation process, and that the result of the difference between the determined soot mass from the estimated soot mass is greater than a predetermined amount, method 300 proceeds to 318 . Otherwise, method 300 proceeds to exit. Thus, if the estimated soot mass is less than the determined soot mass, method 300 proceeds to 318 . [0046] At 318 , method 300 provides an indication of particulate filter leakage. In one example, particulate filter leakage is indicated via a light. In other examples, particulate filter leakage is indicated via a diagnostic code made available to a diagnostic tool. Method 300 proceeds to exit after providing an indication of particulate filter leakage. [0047] At 320 , method 300 corrects differences that may develop between the output of oxygen sensors located upstream and downstream of a particulate filter. In one example, where there is an offset difference between the upstream oxygen sensor and the downstream oxygen sensor, one or the other of the upstream and downstream sensors is selected as a baseline and an offset is determined by subtracting the output of the baseline sensor from the output of the other sensor. The result of the subtraction is then added to the output of the other sensor to correct the difference between sensor outputs. In other examples, where one sensor responds faster than the other sensor the phase difference can be accounted for by post processing the oxygen concentration data. The phase differences may be determined and stored in memory so that phase of the slower sensor can be adjusted according to the phase difference between the faster and the slower sensor. Phase of the slower oxygen sensor may be adjusted by post processing stored oxygen concentration data and passing the data through a filter than corrects for the phase difference between sensors. [0048] It should be noted that differences in oxygen sensor output are corrected when a temperature of the particulate filter is less than a predetermined temperature so that oxidation of soot within the particulate does not affect correcting oxygen sensor output. Further, in some examples, the correction of oxygen sensor output may be reserved for selected operating conditions. For example, when engine speed is greater than a threshold speed and when engine air mass flow is greater than a threshold amount. [0049] Referring now to FIG. 4 , a method for delivering a lean exhaust gas mixture to oxidize soot mass held within a particulate filter is shown. The method of FIG. 4 is executable via instructions of controller 12 within the system of FIG. 1 . [0050] At 402 , method 400 judges whether or not a particulate filter is positioned in an exhaust system at a location upstream of a three-way catalyst. In one example, the vehicle exhaust system configuration may be stored in memory so that a simple enquiry provides an answer to the particulate filter location. Method 400 proceeds to 414 if the particulate filter is not located upstream of a three-way catalyst. Otherwise, method 400 proceeds to 404 . [0051] At 414 , method 400 leans gases entering a particulate filter to achieve a desired rate of soot oxidation within the particulate filter. If air is injected into the exhaust system at a location upstream of the particulate filter the amount of air injected to the exhaust system can be adjusted in response to a temperature of the particulate filter. In some examples, air may be injected to an engine exhaust system in a series of pulses so that a temperature of the particulate filter can be controlled. Method 500 proceeds to 412 after air entering the particulate filter is adjusted. [0052] At 404 , method 400 selects and outputs engine air-fuel ratio amplitude, duty cycle, and frequency for oxidizing soot held within the particulate filter. The air-fuel ratio amplitude, duty cycle, and frequency may be adjusted via changing an amount of fuel injected to each engine cylinder. For example, if it is desired that a lean air-fuel mixture is combusted by the engine, less fuel may be injected to a cylinder. The duty cycle of rich or lean cylinder air-fuel mixtures may be adjusted by varying a number of combustion events for a cylinder when the cylinder combusts a lean or rich air-fuel mixture. In one example, the amount that a cylinder air-fuel mixture is lean may be varied according to the estimated amount of soot held within the particulate filter. For example, if it is estimated that 0.2 grams of soot are stored within the particulate filter, engine cylinders may be operated 0.2 air-fuel ratios leaner than a base commanded engine air-fuel ratio during the lean portion of the base commanded engine air-fuel ratio cycle. On the other hand, if it is estimated that 0.4 grams of soot are stored within the particulate filter, engine cylinders may be operated 0.4 air-fuel ratios leaner than a base commanded engine air-fuel ratio during the lean portion of the base commanded engine air-fuel ratio cycle. [0053] The frequency, rich and lean air-fuel ratio amplitudes about a stoichiometric air-fuel ratio, and air-fuel ratio duty cycle are adjusted to provide a substantially stoichiometric exhaust gas mixture entering the downstream three-way catalyst. Further, the engine air-fuel ratio frequency, rich and lean air-fuel ratio amplitudes, and air-fuel ratio duty cycle are adjusted at 416 and 418 to account for soot mass oxidized. Method 400 proceeds to 406 after the engine air-fuel ratio is adjusted and output. [0054] At 406 , method 400 reads the output of upstream (US) and downstream (DS) oxygen sensors. The oxygen sensor outputs may be read once or several times before proceeding to 408 . Method 400 proceeds to 408 after the outputs of oxygen sensors are read. [0055] At 408 , method 400 judges whether or not a lower level of oxygen than is expected is present in the exhaust gases exiting the particulate filter. A level of oxygen that is lower than is expected may indicate that more soot mass than is estimated is stored within the particulate filter. However, the lower level of oxygen may disturb the chemistry within the three-way catalyst so that oxidation of hydrocarbons and carbon monoxide is efficient. Therefore, the amplitude of the lean portion of the engine air-fuel ratio cycle may be increased so that additional oxygen may pass through the particulate filter and participate in oxidation within the three-way catalyst. In one example, the level of oxygen is lower than expected, when on average over an engine air-fuel ratio cycle, the exhaust gases exiting the particulate filter are richer than a stoichiometric mixture. If method 400 judges that the level of oxygen in gases exiting the particulate filter is less than expected, method 400 proceeds to 416 . Otherwise, method 400 proceeds to 410 . [0056] At 416 , method 400 increases the lean portion of an engine air-fuel ratio cycling pattern. In one example, the lean portion of the air-fuel cycle is leaned by injecting less fuel over a number of combustion events. In other examples, the engine air amount can be increased while the engine fuel amount remains substantially constant. Method 400 proceeds to 410 after the amplitude of the lean portion of the engine air-fuel cycle is increased. [0057] At 410 , method 400 judges whether or not a higher level of oxygen than is expected is present in the exhaust gases exiting the particulate filter. A level of oxygen that is higher than expected it may indicate that less soot mass than is estimated is stored within the particulate filter. However, the higher level of oxygen may disturb the chemistry within the three-way catalyst so that reduction of NOx is less efficient. Therefore, the amplitude of the lean portion of the engine air-fuel ratio cycle may be decreased so that less oxygen may pass through the particulate filter and participate in oxidation within the three-way catalyst. In one example, the level of oxygen is higher than expected, when on average over a time period, the exhaust gases exiting the particulate filter are leaner than a stoichiometric mixture. If method 400 judges that the level of oxygen in gases exiting the particulate filter is greater than expected, method 400 proceeds to 418 . Otherwise, method 400 proceeds to 412 . [0058] At 418 , method 400 decreases the lean portion of an engine air-fuel ratio cycling pattern. In one example, the lean portion of the air-fuel cycle is richened by injecting more fuel over a number of combustion events. In other examples, the engine air amount can be decreased while the engine fuel amount remains substantially constant. Method 400 proceeds to 412 after the amplitude of the lean portion of the engine air-fuel cycle is increased. [0059] In an alternative example, the lean amplitude, frequency of oscillation, and duty cycle of the engine air-fuel ratio are adjusted automatically as the controller determines that the soot mass oxidized approaches the soot mass held within the particulate filter. Thus, 408 , 410 , 416 , and 418 may be replaced with an operation where the lean portion of the engine air-fuel cycle is decreased as an estimated soot mass held within the particulate filter decreases. [0060] At 412 , method 400 judges whether or not the output of a downstream oxygen sensor is in range of the output of an upstream oxygen sensor. If so, the process of oxidation of soot within the particulate filter is stopped and the engine is returned to base operating conditions. Otherwise, method 400 returns to 404 . In this example, when the downstream oxygen sensor indicates an oxygen concentration similar to that indicated by the upstream oxygen sensor while the engine is operating lean and while the particulate filter is at an elevated temperature, it may be determined that a substantial portion soot mass held within the particulate filter has been oxidized. [0061] In an alternative example, method 400 can exit when soot mass determined from upstream and downstream oxygen sensor signals is subtracted from the estimated soot mass held within the particulate filter and the result is less than a threshold soot mass. If the result of subtracting the soot mass determined from oxygen sensors subtracted from the estimated soot mass held within the particulate filter is greater than the threshold soot mass, method 400 returns to 404 . [0062] In this way, the exhaust gases supplied to the particulate filter and the downstream catalyst can be controlled to both oxidize soot in the particulate filter and balance the chemistry within the downstream catalyst for efficient oxidation and reduction. Further, the soot mass can be readily determined from processing and summing the differences in the corrected oxygen sensor output as described in the method of FIG. 5 . In other examples, the air amount entering the particulate filter can be adjusted without adjusting the engine air-fuel amount. For example, air can be periodically added to the particulate filter via an air pump during the process of oxidizing soot mass held within the particulate filter. In such cases, the amount of air entering the particulate filter can be cycled so that, on average, a stoichiometic mixture of gas exits the particulate filter. [0063] Referring now to FIG. 5 , a high level flowchart of a method for determining soot mass oxidized is shown. The method of FIG. 5 is executable via instructions of controller 12 within the system of FIG. 1 . [0064] At 502 , method 500 determines the engine exhaust gas flow rate. In one example, the engine exhaust gas flow rate can be determined from the engine air mass flow rate. [0065] And, the engine air mass flow rate can be determined from an air mass sensor or from engine speed, manifold pressure, and the ideal gas law. In other examples, the exhaust mass flow rate can be determined by a combination of engine air mass flow rate and an estimation of an amount of air external to the engine being pumped into the exhaust system. For example, engine air mass can be determined from a mass air flow sensor and the external air mass can be estimated from a voltage applied to an air pump. Method 500 proceeds to 504 after the exhaust gas mass flow rate is determined. [0066] At 504 , method 500 determines a temperature at the particulate filter. In one example, particulate filter temperature may be determined via a temperature sensor. In another example, particulate filter temperature may be determined from engine air mass, spark timing, and engine speed via a model. Method 500 proceeds to 506 after the particulate filter temperature is determined. [0067] At 506 , method 500 determines a soot oxidation coefficient related to molecular collisions. The soot oxidation coefficient may be empirically determined via experimentation. Further, the soot coefficient may vary for different operating conditions. In one example, the soot oxidation coefficient may be empirically determined and stored in memory of a controller. Where multiple soot coefficients are used, a table or function may be indexed via a variable such as particulate filter temperature to determine a soot coefficient. Method 500 proceeds to 508 after the soot coefficient is determined. [0068] At 508 , method 500 determine the soot mass oxidized during the soot mass oxidation process. In one example, the soot mass oxidized is determined according to an Arrhenius equation. In particular, soot mass oxidized from a particulate filter is determined according to the following equations: [0000]  m_soot  t = - m_soot · O 2 · k 0 ·  ( - k RT ) ( 1 ) O 2  _downstreamPF = O 2  _upstreamPF - k 1 · (  m_soot  t ) exh_flow ( 2 ) [0000] Where m_soot is soot mass, O 2 is amount of oxygen available to oxidize soot, k 0 is a soot oxidation coefficient related to a molecular collision rate, k is activation energy, R is the gas constant, and T is absolute temperature in equation 1. And, where O 2 — downstreamPF is the corrected oxygen concentration downstream of the particulate filter, O 2 — upstreamPF is the corrected oxygen concentration upstream of the particulate filter, k 1 is an empirically determined coefficient, m_soot is soot mass, and exh_flow is exhaust gas flow rate. The soot mass oxidized is updated each time the oxygen sensors located upstream and downstream of the particulate filter are read. [0069] In examples where a three-way catalyst is positioned between a particulate filter and a downstream oxygen sensor, the amount of oxygen stored in the three-way catalyst is considered when determining the amount of soot oxidized by the particulate filter. In particular equation 2 above is modified to include the amount of oxygen stored within the catalyst. [0000] O 2  _downstreamPF = O 2  _upstreamPF - k 1 · (  m_soot  t ) exh_flow - O 2  _catalyst ( 3 ) [0070] Where O 2 — catalyst is an amount of oxygen stored within a catalyst located downstream of the particulate filter. In one example, the amount of oxygen stored within a catalyst may be determined according to the method described in U.S. Pat. No. 6,453,662 which is hereby fully incorporated by reference for all intents and purposes. Again, the soot mass oxidized is updated each time the oxygen sensors are read. Method 500 exits after updating the soot mass oxidized during the soot mass oxidation procedure. [0071] In this way, the soot mass oxidized during a particulate filter soot mass oxidation procedure may be determined. By utilizing information provided by oxygen sensors upstream and downstream of the particulate filter it is possible to determine the soot mass oxidized within a particulate filter. [0072] Thus, the method of FIGS. 3-5 provide for a method for operating a particulate filter, comprising: estimating soot mass oxidized from a particulate filter via first and second oxygen sensors; and indicating degradation of the particulate filter when a difference between the estimated soot mass oxidized from the particulate filter and a desired soot mass held in the particulate filter is greater than a threshold soot mass. The method includes where the first oxygen sensor is positioned in an exhaust system upstream of the particulate filter, and where the second oxygen sensor is positioned downstream of the particulate filter in the exhaust system. In this way, the oxygen consumed via oxidation of soot may be determined. The method also includes where the soot mass is estimated via an Arrhenius equation. The method includes where the first oxygen sensor is located upstream of the particulate filter and where the second oxygen sensor is located downstream of the particulate filter. The method includes where the first and second oxygen sensors are linear oxygen sensors. The method also includes where an output of at least one of the first and second oxygen sensors is compensated during a soot oxidation process of the particulate filter in response to a difference between output of the first oxygen sensor and output of the second oxygen sensor during a period of time when oxidation of soot within the particulate filter is not expected. The method includes where compensation is provided to at least one of the first and second oxygen sensors via adding an offset to an output of the first or second oxygen sensor. Thus, oxygen sensor errors can be extracted from the estimate of particulate filter soot mass. [0073] The methods of FIGS. 3-5 further provide for a method for operating a particulate filter, comprising: adjusting a lean portion of an engine air-fuel ratio cycle in response to soot mass held within a particulate filter; and indicating degradation of the particulate filter when a difference between an estimated soot mass oxidized from the particulate filter via first and second oxygen sensors, and a desired soot mass held in the particulate filter, is greater than a threshold soot mass. The method includes where the lean portion of the engine air-fuel ratio cycle is further adjusted in response to an output of the second oxygen sensor, and where the second oxygen sensor is located downstream of the particulate filter. In this way, a high conversion efficiency of a three-way catalyst located downstream of the particulate filter can be provided. The method includes where a three-way catalyst is positioned in an engine exhaust system downstream of the particulate filter and an engine, and where the engine is a spark ignition engine. The method also includes where the lean portion of the engine air-fuel ratio cycle is further leaned when an oxygen concentration output from the second oxygen sensor is less than expected. In another example, the method includes where the lean portion of the engine air-fuel ratio cycle is richened when and oxygen concentration output from the second oxygen sensor is higher than expected. The method further comprises adjusting a duty cycle of the engine air-fuel ratio cycle in response to an output of the second oxygen sensor, the second oxygen sensor positioned in an exhaust system downstream of the particulate filter. The method also further comprises ceasing to estimate the soot mass oxidized from the particulate filter in response to the output of the second oxygen sensor. [0074] The methods of FIGS. 3-5 further provide for a method for operating a particulate filter, comprising: adjusting a lean portion of an engine air-fuel ratio cycle in response to soot mass held within a particulate filter; initiating combustion of an air-fuel mixture in a cylinder of an engine via a spark, the air-fuel mixture derived from the air-fuel ratio cycle; estimating soot mass oxidized from the particulate filter via first and second oxygen sensors; and indicating degradation of the particulate filter when a difference between the estimated soot mass a desired soot mass is greater than a threshold soot mass. The method also includes where an output of at least one of the first and second oxygen sensors is compensated during a soot oxidation process of the particulate filter in response to a difference between an output of the first oxygen sensor and an output of the second oxygen sensor during a period of time when oxidation of soot within the particulate filter is not expected. The method also includes where compensation includes compensation for signal phase delay between the first and second oxygen sensors. In one example, the method includes where compensation further includes compensation for an offset difference between the output of the first oxygen sensor and an output of the second oxygen sensor. The method also includes where a three-way catalyst is located in an exhaust system of an engine downstream of the particulate filter. The method further comprises where the engine air-fuel ratio cycle is adjusted to provide on average a substantially stoichiometric mixture of exhaust gases exiting the particulate filter. [0075] As will be appreciated by one of ordinary skill in the art, the methods described in FIGS. 3-5 may represent one or more of any number of processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. As such, various steps or functions illustrated may be performed in the sequence illustrated, in parallel, or in some cases omitted. Likewise, the order of processing is not necessarily required to achieve the objects, features, and advantages described herein, but is provided for ease of illustration and description. Although not explicitly illustrated, one of ordinary skill in the art will recognize that one or more of the illustrated steps or functions may be repeatedly performed depending on the particular strategy being used. In addition, the terms aspirator or venturi may be substituted for ejector since the devices may perform in a similar manner. [0076] This concludes the description. The reading of it by those skilled in the art would bring to mind many alterations and modifications without departing from the spirit and the scope of the description. For example, single cylinder, I 2 , I 3 , I 4 , I 5 , V 6 , V 8 , V 10 , V 12 and V 16 engines operating in natural gas, gasoline, diesel, or alternative fuel configurations could use the present description to advantage.

A method for determining soot mass oxidized during a particulate filter oxidation procedure is disclosed. In one example, soot mass is determined via an Arrhenius equation. The approach may provide cost savings and reliability improvements as compared to other ways of determining soot mass.

REFERENCE TO RELATED CASES The present application is a continuation of application Ser. No. 11/827,851, filed on Jul. 13, 2007, the content of which is hereby incorporated by reference in its entirety. Application Ser. No. 11/827/851 claims the benefit of U.S. Provisional Application No. 60/831,010, filed Jul. 14, 2006, the content of which is hereby incorporated by reference in its entirety. BACKGROUND The focus of most current playground play systems is typically centered upon some type of large “post and deck” structure. In general, these systems promote “continuous play” to some extent, for example, where an individual can move from one play element to the next, possibly without ever touching the ground. However, it is typical that there are limited options for traversing from one play element to the next. The possible routes from element to element are often predetermined or even restricted. The design rarely encourages individuals to use their imagination in determining what path to take between elements. One implication of the limitations of current play systems is that they tend to be perceived by older aged kids as being boring or otherwise unappealing. Also, the systems are not very effective in terms of encouraging activities that promote health without sacrificing fun. SUMMARY An aspect of the disclosure relates to play systems having multiple curved structural members. In one embodiment, play systems include a first quarter of an ellipse, a second quarter of an ellipse, a third quarter of an ellipse, and a fourth quarter of an ellipse. Each ellipse quarter has first and second ends. The first, the second, the third, and the fourth ellipse quarters are oriented approximately vertically relative to a surface such that the first ends of the ellipse quarters contact the surface and the second ends of the ellipse quarters are above the surface. The first ends of the ellipse quarters are illustratively spaced further apart from each other than the second ends of the ellipse quarters. These and various other features and advantages that characterize the claimed embodiments will become apparent upon reading the following detailed description and upon reviewing the associated drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an arch-based play system. FIG. 2 is a top plan view of the arch-based play system. FIGS. 3-6 are side views of arch assemblies. FIG. 7 is a schematic flow diagram of an attachment scheme for connecting adjoining arch assembly segments. FIG. 8A is a close up side view of a portion of an arch assembly. FIG. 8B is a side view of an arch assembly demonstrating an example distribution of arch tabs. FIG. 9 is a perspective view of different embodiments of arch clamps. FIG. 10 is a schematic view of a schema for connecting an arch assembly to a play element. FIG. 11 is a side view of an arch assembly footing. FIG. 12 is a perspective view of a stepping surface. FIG. 13 is a perspective view of a ribbon slide. FIG. 14 is a perspective view of a winding slide. FIG. 15 is a perspective view of a cable rope climber. FIG. 16 is a schematic representation of a scheme for attaching an elongated portion of a cable rope climber to an associated net assembly. FIG. 17 is a schematic representation of a cable rope climber turnbuckle assembly. FIG. 18 is a perspective view of a twisted net. FIG. 19 is a perspective view of a climbing net. FIG. 20 is a top view of the climbing net. FIG. 21 is a perspective view of the climbing rings assembly. FIG. 22 is a top view of a climbing rings assembly. FIG. 23 is a perspective view of a pipe climber. FIG. 24 is a perspective view of a rope climbing structure. FIG. 25 is a perspective view of an arched bar structure. FIG. 26 is a perspective view of a hanging bars ladder. FIG. 27 is a perspective view of a pivoting walk-across. FIG. 28 is a perspective view of a cable-disk climber. FIG. 29 is a perspective view of a cable-disk climber platform assembly. FIG. 30 is a perspective view of a ringed spinner. FIG. 31 is a diagrammatic representation of a ringed spinner bottom portion and footer connection. FIG. 32 is a side view of a ringed spinner footing. FIG. 33 is a diagrammatic representation of a ringed spinner upper spinner mount and ring assembly connection. FIG. 34 is a perspective view of a spiral spinner. FIG. 35 is a perspective view of a talking post. FIG. 36 is a schematic representation of a talking post footing scheme. FIG. 37 is a perspective view of a cycler. FIG. 38 is an exploded view of a cycler handhold assembly. FIG. 39 is a perspective view of a curved post. FIG. 40 is an exploded view of a spring bench. FIG. 41 is a perspective view of one embodiment of an arch-based play system with integrated play elements. FIG. 42 is a perspective view of another embodiment of an arch-based play system. FIG. 43 is a perspective view of an arch assembly and an imaginary circle. FIG. 44 is a top view of two arch assemblies and their imaginary circles. FIG. 45 is a top view of four arch assemblies and their imaginary circles. FIG. 46 is a perspective view of an arch assembly and an imaginary line. DETAILED DESCRIPTION FIG. 1 is a perspective view of an arch-based play system 100 . System 100 includes arch assemblies 101 , 102 , 103 , and 104 . System 100 also includes a plurality of arch clamps 105 (an illustrative two are identified in FIG. 1 ). Also included are a plurality of arch tabs 106 (an illustrative two are identified in FIG. 1 ). Before proceeding further into the present description, it is worth noting that the terms “arch” and “arch assembly” as used herein are not necessarily limited to an upwardly curved structures as shown in FIG. 1 . Those skilled in the art will appreciate that similar over arching structures can be utilized even if such structures do not have a continuous uninterrupted curvature. The illustrated embodiment is one example of the type of structure that is to be considered within the scope of the present invention. As will become apparent, system 100 is modular in that a wide variety of different play elements can be incorporated into the arch-based environment. Depending upon a connection scheme necessary to support the components of a given implementation, arch tabs 106 may or may not be included in system 100 , and may be located within the system in locations other than their positions illustrated in FIG. 1 . Further, as will become apparent, the precise configuration of arch clamps 105 may vary depending on the component attachment details associated with a given implementation. FIG. 2 is a top plan view of arch-based play system 100 . It should be noted that all dimensions provided herein are intended to be illustrative only. Specific dimensions are provided as an example of scale and are not intended to limit the scope of the present invention in any way. Those skilled in the art will appreciate that the dimensions can easily be adjusted without departing from the scope of the present invention. It should also be pointed out that the positioning of arches relatively to one another as shown and described herein is also illustrative only. A specific configuration is provided as an example of the concept and is not intended to limit the scope of the present invention in any way. Those skilled in the art will appreciate that the arches can easily be otherwise configured without departing from the scope of the present invention. As is shown in FIG. 2 , the ends of arch assemblies 101 , 102 , 103 , and 104 are all positioned in substantial alignment with the circumference of an imaginary circle 107 . Of course, this need not necessarily be the case. The end of one or more arches could just as easily be outside of a common circumference without departing from the scope of the present invention. In one embodiment, certainly not by limitation, the diameter of circle 107 is 40 feet and 10 inches. In one embodiment, certainly not by limitation, a distance 108 between one end of arch assembly 101 and one end of arch assembly 104 is 164 and 13/16 inches. In one embodiment, certainly not by limitation, the distance 109 between one end of arch assembly 104 and one end of arch assembly 103 is 31 and 11/16 inches. In one embodiment, certainly not by limitation, the distance 110 between one end of arch assembly 103 and one end of arch assembly 101 is 93 and 3/16 inches. In one embodiment, certainly not by limitation, the distance 111 between one end of arch assembly 101 and one end of arch assembly 103 is 80 and ⅞ inches. In one embodiment, certainly not by limitation, the distance 112 between one end of arch assembly 103 and one end of arch assembly 102 is 22 and 7/16 inches. In one embodiment, certainly not by limitation, the distance 113 between one end of arch assembly 102 and one end of arch assembly 104 is 165 and ¾ inches. In one embodiment, certainly not by limitation, the distance 114 between one end of arch assembly 104 and one end of arch assembly 102 is 119 and 3/16 inches. In one embodiment, certainly not by limitation, the distance 115 between one end of arch assembly 102 and one end of arch assembly 101 is 33 and ⅝ inches. It is worth emphasizing yet again the modular and adaptable nature of system 100 . The system shown in the Figures is but one of a great number of possible configurations within the scope of the present invention. Configurations can include any number of arch assemblies, and the arch assemblies can be spaced apart as desired. It is also worth mentioning that a beneficial feature of system 100 is that the arch-based system can be expanded in phases by starting with one or more arch assemblies and then adding additional arch assemblies after an initial arch-based play system has been formed. As will become apparent, play elements can be incorporated into the initial system and/or added during any subsequent phase of expansion of the system. In one embodiment, the FIG. 2 distances 109 , 112 , and 115 are such that they create a “modular opening” or “attachment point” where play elements can be attached. FIG. 3 is a side view of arch assembly 101 . In this case, clamps 105 have been excluded to show that the arch assembly is actually comprised of separate segments. In one embodiment, one function of clamps 105 is to conceal a connection between segments of the overall assembly. Arch assembly 101 includes segments 101 a , 101 b , 101 c , and 101 d . In one embodiment, not by limitation, segment 101 a has an end-to-end linear distance 201 of approximately 103.5 inches, segment 101 b has an end-to-end linear distance 202 of approximately 98.75 inches, segment 101 c has an end-to-end linear distance 203 of approximately 93.5 inches, and segment 101 d has an end-to-end linear distance 204 of approximately 103.5 inches. Also in one embodiment, not by limitation, the distance 205 between the first end of the arch assembly 206 and the second end of the arch assembly 207 is 230 inches, and the distance 208 between the top of the arch assembly 209 and the bottom of the arch assembly is 105 inches. Although arch assembly 101 is illustrated as including four segments, arch assemblies need not be so limited. An arch assembly can include only one piece (i.e. not segmented), two segments, three segments, four segments (as is shown in FIG. 3 ), or any number of segments. FIG. 4 is a side view of arch assembly 102 . In this case, clamps 105 have again been excluded. Arch assembly includes segments 102 a , 102 b , 102 c , and 102 d . In one embodiment, not by limitation, segment 102 a has an end-to-end linear distance 210 of approximately 103.5 inches, segment 102 b has an end-to-end linear distance 211 of approximately 98.75 inches, segment 102 c has an end-to-end linear distance 212 of approximately 93.5 inches, and segment 102 d has an end-to-end linear distance 213 of approximately 103.5 inches. Also in one embodiment, not by limitation, the distance 214 between the first end of the arch assembly 215 and the second end of the arch assembly 216 is 230 inches, and the distance 217 between the top of the arch assembly 218 and the bottom of the arch assembly is 105 inches. FIG. 5 is a side view of arch assembly 103 . In this case, clamps 105 have again been excluded. Arch assembly 103 includes segments 103 a , 103 b , 103 c , and 103 d . In one embodiment, not by limitation, segment 103 a has an end-to-end linear distance 219 of approximately 103.5 inches, segment 103 b has an end-to-end linear distance 220 of approximately 80.5 inches, segment 103 c has an end-to-end linear distance 221 of approximately 75 inches, and segment 103 d has an end-to-end linear distance 222 of approximately 103.25 inches. Also in one embodiment, not by limitation, the distance 223 between the first end of the arch assembly 224 and the second end of the arch assembly 225 is 163 inches, and the distance 226 between the top of the arch assembly 227 and the bottom of the arch assembly is 111 inches. FIG. 6 is a side view of arch assembly 104 . Arch assembly 104 includes segments 104 a , 104 b , 104 c , and 104 d . In one embodiment, not by limitation, segment 104 a has an end-to-end linear distance 228 of approximately 104.5 inches, segment 104 b has an end-to-end linear distance 229 of approximately 135.5 inches, segment 104 c has an end-to-end linear distance 230 of approximately 130.5 inches, and segment 104 d has an end-to-end linear distance 231 of approximately 104.5 inches. Also in one embodiment, not by limitation, the distance 232 between the first end of the arch assembly 233 and the second end of the arch assembly 234 is 237 inches, and the distance 235 between the top of the arch assembly 236 and the bottom of the arch assembly is 147 inches. In one embodiment, not by limitation, arch assemblies 101 , 102 , 103 , and 104 are manufactured from galvanized steel tubing. Those skilled in the art will appreciate that other materials can be utilized without departing from the scope of the present invention. In one embodiment, not by limitation, arch assemblies 101 , 102 , 103 , and 104 have an outer diameter of approximately 5 inches and a wall thickness of approximately 0.120 inches. The cut ends of the steel tubing are illustratively sprayed with a corrosion resistant coating and the exterior surfaces of the arches are illustratively provided with some sort of a finishing coating, such as a powdercoat finishing. It should also be noted that the arch assembly first end to second end distances such as 205 , 214 , 223 , and 232 can be varied from the stated distances. In one embodiment, the end to end distances of the arch assemblies are spaced apart by a distance of at least six feet. In one embodiment, all of the bottom arch segments such as 201 , 204 , 210 , 213 , 219 , 222 , 228 , and 231 are the same or similar length despite differences in overall height and lengths of the arch assemblies. This allows for arch clamps to cover the seams of the arch assemblies at approximately the same height. This also facilitates attaching a play element to more than one arch assembly. FIG. 7 is a schematic flow diagram demonstrating one embodiment of an attachment scheme for connecting adjoining arch assembly segments. In step 301 , the end of one arch segment 310 and the end of another arch segment 311 are not attached. In step 302 , end 310 that has an outer-diameter that is smaller than the inner-diameter of end 311 , is partially inserted into end 311 in such a way that a certain portion of 310 represented by the distance 314 in encased by 311 . Also in step 302 , preparation is made to connect ends 310 and 311 with rivets 312 and 313 . In step 303 , rivets 312 and 313 have been driven through the overlapping section 314 and the arch segments are attached. In one embodiment, this or a similar method of attaching adjoining arch assembly segments is employed to attach all adjoining segments shown in FIGS. 3-6 . FIG. 8A is a close up side view of a portion 401 of arch assembly 104 ( FIG. 1 ). Arch tabs 106 are attached to portion 401 and are configured to receive an attachment mechanism, such as a mechanism associated with a play element. Multiple (e.g., two) arch tabs located in relatively close proximity to one another illustratively constitute a set 421 of arch tabs. FIG. 8B is a side view of arch assembly 104 with a clearer depiction of one embodiment, not by limitation, of a distribution of the associated arch tabs. Arch assembly 104 includes multiple sets of arch tabs 421 running along the length of the assembly. Those skilled in the art will appreciate that any arch assembly can include any number of arch tabs, and in any configuration, without departing from the scope of the present invention. FIG. 9 is a perspective view of several different embodiments of arch clamps 105 . Arch clamps 105 can be configured to serve a variety of different purposes within system 100 ( FIG. 1 ). For example, they can be utilized to cover (and secure) the seams between arch segments. Further, they can be utilized to add aesthetic value to the system based on their own appearance and/or by covering any portion of the system having a relatively unappealing visual quality. Each arch clamp 105 illustratively includes two main portions, 510 and 511 , that are configured to be connected to each other utilizing a connection mechanism such as, but not necessarily limited to, screws 512 . Portions 510 and 511 together define an opening 515 . As is illustrated, opening 515 is configured to receive an arch assembly (arch 104 is shown for illustrative purposes) when portions 510 and 511 are secured together. In one embodiment, in this manner, an arch clamp 105 can be firmly secured to an arch assembly. It should be noted that the scope of the present invention is not limited to securing clamps 105 to an arch assembly. Opening 515 can be otherwise configured to support attachment to an elongated member other than an arch assembly (e.g., attachment to a play element added to system 100 , the play element requiring an opening 515 with a different circumference). In one embodiment, as is illustrated, an arch clamp 105 can include one or more connection surfaces 512 . In general, connection surfaces 512 are configured to support a connection between an arch clamp 105 and another element within system 100 (e.g., a play element added to the system). Those skilled in the art will appreciate that surface 512 can be configured to support any of a variety of different attachment schemes. In one embodiment, as will be described in more detail in relation to FIG. 10 , connection surfaces 512 are configured to support connection to a ball clamp. In accordance with this embodiment, a surface 512 , which is collectively formed by portions 510 and 511 , includes a flat surface with openings to accommodate engagement to one or more attachment mechanisms (e.g., engagement to four screws) associated with a ball clamp. The nature of this engagement will become more apparent upon the description of FIG. 10 below. In one embodiment, an arch clamp 105 includes two connection surfaces 512 , wherein the plane comprising one surface and the plane comprising the other surface form an approximate right angle relative to one another. In another embodiment, connection surfaces 512 are on opposite sides of the arch clamp 105 . Those skilled in the art will appreciate that a given arch clamp 105 can have one, two, three or more connection surfaces 512 depending upon the need for attachments within a given implementation. FIG. 10 is a perspective view of an embodiment of a ball clamp 600 . Ball clamps are used to connect elements such as (but not necessarily limited to) play elements to arch clamps. In this manner, elements are added to system 100 . Examples of specific elements that can be added to system 100 will be described below in relation to other Figures. A ball clamp 600 illustratively includes two main portions. In one embodiment, a first portion 601 is configured for mounting to a connection surface 512 of an arch clamp 105 . Portion 601 is also configured to receive a ball 611 associated with an element 610 . In one embodiment, not by limitation, portion 601 also includes one or more openings 605 . In one embodiment, an attachment mechanism such as a screw (not shown) is inserted through an opening 605 and engaged to a corresponding opening in an attachment surface 512 so as to secure portion 601 to an arch clamp 105 . Ball clamp 600 also includes a second portion 602 that is configured to receive the ball 611 and to firmly connect to portion 601 utilizing a connection mechanism such as, but not necessarily limited to, screws 603 . Those skilled in art will appreciate that a ball clamp 600 enables a secure connection of element 610 to an arch clamp 105 (i.e., ball clamp 600 is secured to a surface 512 and securely contains a ball 611 ). FIG. 11 is a side view of an arch assembly footing 700 illustratively utilized at each end of an arch assembly (e.g., assembly 101 , 102 , 103 or 104 ) in order to secure the structure in the ground. This is but one example of an appropriate footing to which the scope of the present invention is not limited. Footing 700 includes a foot portion 701 . Portion 701 is positioned upon crushed rock 702 (e.g., at least four inches). In one embodiment, portion 702 is encased by a cylindrical concrete footing 703 (e.g., height of at least 30 inches and a minimum diameter of 24 inches). In one embodiment, a protective surface 704 is included in the form of loose-fill material or pour-in-place material. FIG. 12 is a perspective view of an embodiment of a stepping surface 800 . A stepping surface enables a user of system 100 to move from one place to another, for example without touching the ground. Any number of stepping surfaces can be integrated into system 100 without departing from the scope of the present invention. Stepping surface 800 includes two portions. A portion 801 is configured to partially surround an arch assembly (e.g., assembly 101 , 102 , 103 or 104 ). A portion 802 is configured to partially surround a remaining portion of the arch assembly. A connection mechanism such as, but not limited to, screws or bolts are utilized to secure portions 801 and 802 to one another, thereby securing the stepping surface to the arch assembly. Stepping surfaces 800 can alternatively be attached to any other element within system 100 (e.g., attached to a play element). Those skilled in the art will appreciate that the opening formed between portions 801 and 802 can be sized to accommodate attachment to any of a variety of different elements. Those skilled in the art will understand that many different types of play elements can be incorporated into system 100 . The scope of the present invention is not limited to any one element or any combination of elements. However, for the purpose of providing a complete description, a broad range of specific examples of element implementations will be provided. The present invention is not limited to any one illustrated example, nor to any combination of illustrated examples. FIG. 13 is a perspective view of a first example of a play element that can be incorporated into system 100 . The play element in FIG. 13 is a ribbon slide 900 . Ribbon slide 900 includes a curved stepping pole 901 , two crossover bars 902 , two rails 903 , and two attachments 904 . Attachments 904 are illustratively configured to connect to an arch assembly. In one embodiment, attachments 904 are consistent with the attachment scheme described above in relation to FIG. 10 . In one embodiment, certainly not by limitation, the two ribbon slide rails 903 are substantially parallel and separated by a distance of approximately 12 inches. Stepping pole 901 and rails 903 are illustratively secured to the ground using footings, possibly similar to the footing scheme described above in relation to FIG. 11 . Ribbon slide 900 can be used in many different ways. For example, one could climb up stepping pole 901 and then work his/her way down to the ground using one or both of the ribbon slide rails 903 for support. In another example, one could use crossover bars 902 as an aid to move onto the slide rails and/or from one arch assembly to another. These are simply two of many play options that will be apparent to those skilled in the art. FIG. 14 is a perspective view of another example of a play element that can be incorporated into system 100 . The play element in FIG. 14 is a winding slide 1000 . Winding slide 1000 includes a stepping pole 1001 , two crossover bars 1002 , a mid-support 1003 , an exit support 1004 , a winding slide panel 1005 , and two attachments 1006 . Attachments 1006 are illustratively configured to connect to an arch assembly. In one embodiment, attachments 1006 are consistent with the attachment scheme described above in relation to FIG. 10 . Stepping pole 1001 , mid-support 1003 , and exit support 1004 are illustratively secured to the ground using footings, such as footings similar to those described above in relation to FIG. 11 . Winding slide 1000 can be used in many different ways. For example, one could climb up stepping pole 1001 and then work his/her way down to the ground using winding slide panel 1005 . In another example, one could use crossover bars 1002 as an aid to move onto panel 1005 and/or from one arch assembly to another. These are simply two of many play options that will be apparent to those skilled in the art. FIG. 15 is a perspective view of another example of a play element that can be incorporated into system 100 . The play element in FIG. 15 is a cable rope climber 1100 . Cable rope climber 1100 includes two auxiliary arches 1101 , a cable rope net assembly 1102 , and auxiliary arch tabs 1103 . Also included are attachments 1104 , which are illustratively configured to connect to an arch assembly. In one embodiment, attachments 1006 are consistent with the attachment scheme described above in relation to FIG. 10 . In one embodiment, auxiliary arches are secured to the ground using footings, such as footings similar to the concrete footing shown in FIG. 11 . FIG. 16 is a diagrammatic representation of one embodiment, not by limitation, of a connection between an auxiliary arch tab 1103 and a portion of net assembly 1102 . As is shown, the connection scheme involves an engagement between an auxiliary arch tab 1103 and a cable rope climber net assembly end connector 1204 , which is secured by a connection mechanism such as but not limited to the illustrated screw 1205 . In one embodiment, end connector 1204 is illustratively configured to attach to arch tab 1202 in such a way that the end connector is allowed to rotate around the axis of the screw. FIG. 17 is a side view of one embodiment of a turnbuckle assembly for cable rope climber 1100 . Two turnbuckle assemblies are illustratively used to secure cable rope climber net 1102 to the ground. Each assembly illustratively includes a turnbuckle 1301 and a footer portion 1302 . Turnbuckle 1301 is illustratively configured to connect the footer 1302 to net 1102 . Footer 1302 is secured by a footing 1304 (e.g., a concrete footing). In one embodiment, the turnbuckle and footer are covered with loose fill material 1305 . Cable rope climber 1100 can be used in many different ways. For example, one could climb upon cable rope net 1102 and work from one end to the other. This is but one of many play options that will be apparent to those skilled in the art. FIG. 18 is a perspective view of another embodiment of a play element that can be incorporated into system 100 . The play element in FIG. 18 is a twisted net 1400 . Element 1400 includes a first twisted net railing 1401 , a second twisted net railing 1402 , footers 1403 , attachments 1407 , and a net assembly 1404 . Attachments 1407 are illustratively configured to connect to an arch assembly. In one embodiment, attachments 1407 are consistent with the attachment scheme described above in relation to FIG. 10 . In one embodiment, certainly not by limitation, railing 1401 is approximately 92.5 inches long and railing 1402 is approximately 47.75 inches long. In one embodiment, railings 1401 and 1402 include tabs 1405 that run along the length of the railings and are used to attach net assembly 1404 to the railings. In one embodiment, tabs 1405 and net assembly 1404 incorporate an attachment scheme the same or similar to the scheme described above in relation to FIG. 16 . In one embodiment, each of railings 1401 and 1402 includes a sleeve member 1406 that connects to a footer 1403 to provide additional support. In one embodiment, footers 1403 are similar to the concrete footing described above in relation to FIG. 11 . Twisted net 1400 can be used in many different ways. For example, one could support his/herself using any or all of railing 1401 , railing 1402 and net assembly 1404 . One could work from one end of net 1404 to the other. This is but one of many examples of play options that will be apparent to those skilled in the art. FIG. 19 is a perspective view of another example of a play element that can be incorporated into system 100 . The play element in FIG. 19 is a climbing net 1500 . A top view of climbing net 1500 is shown in FIG. 20 . Climbing net 1500 is illustratively integrated into an arch assembly which, for illustrative purposes only, is identified in FIGS. 19 and 20 as arch assembly 104 . Climbing net 1500 includes arch tabs 1502 , a net assembly 1503 , footers 1504 and footings 1505 . The net assembly 1503 is attached to both arch tabs 1502 and to footers 1504 . In one embodiment, the attachment scheme utilized to connect net assembly 1503 to the arch assembly 104 is the same or similar to the attachment scheme described above in relation to FIG. 16 . Each footer 1504 is illustratively secured to the ground by footings 1505 . In one embodiment, footings 1505 are the same or similar to the footing described above (e.g., in relation to FIG. 11 or FIG. 17 ). Net assembly 1503 is illustratively placed in some degree of tension such that the net is relatively tight and stable. Climbing net 1500 can be used in many different ways. For example, one could go from the ground to the top of an arch assembly, or one could use the element to transfer from one play element to another. These are just two of many play options that will be apparent to those skilled in the art. FIG. 21 is a perspective view of another example of a play element that can be incorporated into system 100 . The play element in FIG. 21 is a climbing rings assembly 1600 . A top view of the element is shown in FIG. 22 . Climbing ring assembly 1600 is illustratively implemented in relation to two arch assemblies, which, or illustratively purposes only, are identified in FIG. 21 as arch assemblies 102 and 104 . Climbing rings assembly 1600 includes arch assembly tabs 1602 , rings 1603 and cables 1604 . For each ring, one cable attaches to arch assembly 104 , another cable attaches to arch assembly 102 , and another cable attaches to a footing. In one embodiment, the attachment scheme utilized to connect a ring 1603 via its associated cables is the same or similar to the attachment scheme described above in relation to FIG. 16 . In one embodiment, the footing beneath each ring is similar to the footing scheme described above (e.g., in relation to FIG. 11 or FIG. 17 ). In one embodiment, the lengths of the cables utilized to suspend the rings are chosen such that the rings are aligned in an arch configuration, as is best illustrated in FIG. 21 . Each ring 1603 is illustratively placed in some degree of tension such that it is relatively tight and stable. Climbing rings assembly 1600 can be used in many different ways. For example, one could go through rings 1603 from one end to the other. Or, one could use the rings assembly to transfer from one play element to another. These are just two of many play options that will be apparent to those skilled in the art. FIG. 23 is a perspective view of another example of a play element that can be incorporated into system 100 . The play element in FIG. 23 is a pipe climber 1700 . Pipe climber 1700 includes two arches 1701 connected by alternating sinusoidal-like crossbars 1702 and by arch-shaped crossbars 1703 . In one embodiment, stepping surfaces 800 , such as surfaces the same or similar to those described above in relation to FIG. 12 , are included to increase accessibility of the play element. Attachments 1705 are included on the top ends of arches 1701 . Attachments 1705 are illustratively configured to connect to an arch assembly. In one embodiment, attachments 1705 are consistent with the attachment scheme described above in relation to FIG. 10 . The opposite ends of arches 1701 are configured to attach to a footing, such as a footing the same or similar that described above in relation to FIG. 11 . Pipe climber 1700 can be used in many different ways. For example, one could use the crossbars to move from the ground to an elevated position in which access to another play element is possible. This is but one of the many play options that will be apparent to those skilled in the art. FIG. 24 is a perspective view of another example of a play element that can be incorporated into system 100 . The play element in FIG. 24 is rope climbing structure 1800 . Structure 1800 includes a climb across auxiliary arch 1801 , auxiliary arch tabs 1802 , a climb across auxiliary arch support 1803 , a net assembly 1804 , and a footer assembly 1805 . The auxiliary arch 1801 includes attachments at each end configured to connect to an arch assembly. In one embodiment, the attachments are consistent with the attachment scheme described above in relation to FIG. 10 . In one embodiment, arch 1801 also includes a sleeve 1806 configured to support a connection to one end of arch support 1803 . The other end of arch support 1803 is illustratively secured to the ground using a footing, possibly similar to the footing scheme described above in relation to FIG. 11 . Arch tabs 1802 run along the length of auxiliary arch 1801 and are configured to support net assembly 1804 . In one embodiment, the connection between auxiliary arch 1801 and net assembly 1804 is accomplished utilizing a tab-oriented connection scheme such as a scheme that is the same or similar to that described above in relation to FIG. 16 . The bottoms of net assembly 1804 can be connected to footers (e.g., so as to apply a tension to the netting) in any of a variety of different ways that will be apparent to those skilled in the art. Footer assembly 1805 is shown in dots to indicate that it is but one of many alternatives. Footer assembly 1805 eliminates the need for more than two in-ground footings. Rope climbing structure 1800 can be used in many different ways. One could use the net structure to support oneself off from the ground and transfer between play elements without touching the ground. One could also climb the net from the ground, cross over the top of the net, and reach the opposite side. These are simply two of many play options that will be apparent to those skilled in the art. FIG. 25 is a perspective view of another example of a play element that can be incorporated into system 100 . The play element in FIG. 25 is an arched bar structure 1900 . Structure 1900 includes two auxiliary arches 1901 (illustratively but not necessarily the arches are parallel relative to one another), hanging bars 1902 (illustratively but not necessarily perpendicular to and connecting auxiliary arches 1901 ), and footers 1903 . One end of each auxiliary arch 1901 includes an attachment for connection to an arch assembly. In one embodiment, the attachments are consistent with the attachment scheme described in relation to FIG. 10 . The other end of each auxiliary arch is configured to attach to a footer 1903 , possibly similar to the footing scheme described above in relation to FIG. 11 . Arched bar structure 1900 can be used in many different ways. For example, one could support him or herself on top of the auxiliary arches and slide from the top of the structure to the bottom. One could also use the hanging bars to pull oneself from the ground to an elevated position and transfer to another play element. These are simply two of many play options that will be apparent to those skilled in the art. FIG. 26 is a perspective view of another embodiment of a play element that can be incorporated into system 100 . The play element in FIG. 26 is a hanging bars ladder 2000 . Hanging bars ladder 2000 includes two auxiliary arches 2001 connected to each other by bars 2002 . An attachment is located on each end of the auxiliary arches and enables a connection to an arch assembly. In one embodiment, the attachments are consistent with the attachment scheme described above in relation to FIG. 10 . Hanging bar ladder 2000 can be used in many different ways. For example, one can support themselves off from the ground by holding onto the bars and can then cross the distance of the ladder without touching the ground. This is but one of many play options that will be apparent to those skilled in the art. FIG. 27 is a perspective view of another embodiment of a play element that can be incorporated into system 100 . The element in FIG. 26 is a pivoting walk-across 2100 . Pivoting walk-across 2100 includes two handrails 2101 and a pivoting assembly 2102 . An attachment is located on one end of each handrail and enables a connection to an arch assembly. In one embodiment, the attachments are consistent with the attachment scheme described above in relation to FIG. 10 . Pivoting assembly 2102 includes platform structures 2103 , a pivoting assembly base 2104 , and a seesaw leg 2105 . Platform structures 2103 provide a surface to accommodate standing or sitting and are supported by pivoting assembly base 2102 . The pivoting assembly base 2102 connects to seesaw leg 2105 in such a way as to enable the platform structures to move in an up-and-down in a seesaw-like fashion. The seesaw leg is illustratively mounted to the ground, for example, by way of concrete footing. Pivoting walk-across 2100 can be used in many different ways. For example, children can teeter up-and-down while supporting their feet on the platform structures and supporting their hands on the handrails. This is but one of many play options that will be apparent to those skilled in the art. FIG. 28 is a perspective view of another example of a play element that can be incorporated into system 100 . The play element in FIG. 28 is a cable-disk climber 2200 . Cable-disk climber 2200 includes an auxiliary arch 2201 , auxiliary arch tabs 2202 , a support bar 2203 , platform cables 2204 , and platform assemblies 2205 . The ends of auxiliary arch 2201 are configured to connect to an arch assembly. In one embodiment, this connection is made in a manner that is the same or similar to the connection scheme described above in relation to FIG. 10 . Auxiliary arch 2201 includes a sleeve 2206 that is configured to facilitate to support bar 2203 . The auxiliary arch tabs 2202 run along the length of auxiliary arch 2201 and are configured to connect to and support platform cables 2204 . The platform cables 2204 are configured such that one end of each cable connects to and hangs from an arch tab 2202 and the other end connects to a footer in the ground. In one embodiment, the connection between a cable 2204 and arch 2201 is accomplished in a manner that is the same or similar to the connection scheme described in relation to FIG. 16 . FIG. 29 is a perspective view of an embodiment of a cable-disk climber platform assembly 2205 . Assembly 2205 includes a platform 2301 and a cable bracket 2302 . Platform 2301 includes a platform aperture 2303 that allows platform cable 2204 to pass through the platform. Cable bracket 2304 is attached to cable 2204 and has a surface 2304 configured to support platform 2301 . The platform and bracket are secured together utilizing a connection mechanism such as, but not necessarily limited to, screws 2305 . Cable-disk climber 2200 can be used in many different ways. For example, children can support themselves using the platform cables only and swing from one cable to another. Children could also use both the cables and platform assemblies to support themselves and cross from one end of the structure to the other. These are simply two of many play options that will be apparent to those skilled in the art. FIG. 30 is a perspective view of another example of a play element that can be incorporated into system 100 . The play element in FIG. 30 is a ringed spinner 2400 . Ringed spinner 2400 includes an upper spinner mount 2401 , a ring assembly 2402 , and a footer 2403 . The upper spinner mount includes two bars joined together in a “V” shaped fashion. The two top ends of the “V” each include an attachment for connection to an arch assembly. In one embodiment, the attachments are consistent with the attachment scheme described in relation to FIG. 10 . The bottom end of the “V”, portion 2404 , is configured to support the ring assembly in such a way as to allow the ring assembly to rotate. The ring assembly includes two ring shaped structures 2405 attached by a middle bar 2406 . The ring assembly bottom end 2407 and footer 2403 are configured to be secured together in such a way that the ring assembly can rotate. FIG. 31 is a diagrammatic representation of one embodiment, not by limitation, of a connection between a ring assembly bottom portion 2407 and a ring assembly footer element 2403 . Portion 2407 illustratively includes a spiral retainer groove 2501 . Footer 2403 includes a spiral retainer 2502 . In one embodiment, retainer 2502 is inserted into groove 2501 and the bottom ring assembly portion and ring assembly footer are secured together utilizing bushings 2503 . FIG. 32 is a side view of a ringed spinner footing 2600 illustratively utilized to support the end of a ringed spinner in order to secure the structure to the ground. This is but one example of an appropriate footing to which the scope of the present invention is not limited. In footing 2600 , the ring assembly bottom 2407 and ring assembly footer 2403 are secured together and are tilted at an angle 2601 (e.g., eighty degrees) from the surface of the ground. Footer 2403 is encased by a cylindrical concrete footing 2602 (e.g., height of at least 20 inches and a minimum diameter of 12 inches), and footing 2602 rests upon crushed rock 2603 (at least 3 inches). In one embodiment, the concrete footing is covered with loose fill material 2604 . FIG. 33 is a diagrammatic representation of one embodiment, not by limitation, of a connection between a ringed spinner upper spinner mount 2401 and ring assembly 2402 . The connection secures the two components together while allowing the ring assembly to rotate. Ring assembly 2402 includes a spherical attachment 2701 that is enclosed by bushings 2702 . Bushings 2702 are configured to receive a screw on the outer portion 2703 . Upper spinner mount 2401 is configured to receive a screw at portion 2704 and to receive the bushings at portion 2705 . The bushings with the spherical attachment enclosed is inserted into portion 2705 and secured to the spinner mount by a connection mechanism such as but not limited to the illustrated screw 2706 . It should be noted that the connection scheme shown and discussed above in relation to FIG. 31 is somewhat similar to that shown in FIG. 33 . In one embodiment, either scheme can be used in either case (i.e., both schemes will work for both elements). Ringed spinner 2400 can be used in many different ways. For example, one could stand on the ground and spin the ring assembly around. One could also support him or herself on the ring assembly and rotate back-and-forth. These are simply two of many play options that will be apparent to those skilled in the art. FIG. 34 is a perspective view of another example of a play element that can be incorporated into system 100 . The play element in FIG. 34 is a spiral spinner 2800 . Spiral spinner 2800 includes an upper spinner mount 2801 , a spiral assembly 2802 , and a footer 2803 . The upper spinner mount includes two bars joined together in a “V” shaped fashion. The two top ends of the “V” each include an attachment for connection to an arch assembly. In one embodiment, the attachments are consistent with the attachment scheme described in relation to FIG. 10 . The bottom of the “V”, portion 2804 , is configured to support the spiral assembly in such a way as to allow the spiral assembly to rotate. The ring assembly bottom end 2805 and footer 2803 are configured to be secured together in such a way that the spiral assembly can rotate. In one embodiment, end 2805 and footer 2803 are secured together in a manner that is same or similar to the scheme described above in relation to FIG. 31 , and the footer is mounted in a manner that is same or similar to the scheme described above in relation to FIG. 32 . Also in an embodiment, upper spinner mount 2801 and spiral assembly 2802 are secured together in a manner that is same or similar to the scheme described above in relation to FIG. 33 . Spiral spinner 2800 can be used in many different ways. For example, one could stand on the ground and spin the ring assembly around. One could also support him or herself on the ring assembly and rotate back-and-forth. These are simply two of many play options that will be apparent to those skilled in the art. In addition to play elements attached to one or more arch assemblies, an arch-based play system may also include additional play elements in the environment that are not necessarily attached to an arch assembly. These “unattached” play elements contribute to creating a continuous and innovative play system. Several illustrative embodiments of such play elements are described below. FIG. 35 is a perspective view of an example of an “unattached” play element that can be incorporated into system 100 . The play element in FIG. 35 is a talking post 2900 . FIG. 36 is a side view of a bottom portion 2950 of talking post 2900 . Talking post 2900 includes a talking ball 2901 , a talking ball plate 2902 , a talking tube hose 2903 , and a post 2905 . The bottom of the talking post 2906 is positioned upon crushed rock 2907 and is encased in a cylindrical concrete footing 2908 . In one embodiment, concrete footing 2908 is covered by a covering 2910 . Talking post 2900 includes an aperture 2912 located above the concrete footing in which talk tube hose 2903 can exit. Talking ball plate 2902 includes openings in the plate 2913 to permit sound waves to enter and leave the talking tube hose, and also includes apertures 2914 so that the plate can be secured to the talking ball utilizing a connection mechanism such as, but not necessarily limited to, screws or bolts (not shown). In one embodiment of a talking post, a stepping surface 800 is secured to a talking post. In another embodiment, two talking post share a talk tube such that sound waves can travel from one talking post to the other. Talking post 2900 can be used in many different ways. For example, if two talking posts share a talk tube, users can speak into one talking post and be heard at the other. This is but one of many play options that will be apparent to those skilled in the art. FIG. 37 is a perspective view of another example of a play element that can be incorporated into system 100 . The play element in FIG. 37 is a cycler 3000 . Cycler 3000 includes a cycler post 3001 and two handhold assemblies 3002 . FIG. 38 is an exploded view of an embodiment of a cycler handhold assembly 3002 . Handhold assembly 3002 includes a shaft 3003 , a crank 3004 , bushings 3005 , and handles 3006 . Handhold assemblies 3002 are mounted in such a way that the handles can be rotated in a manner similar to as how bicycle pedals are rotated. In one embodiment, the bottom of the talking post sits upon crushed rock and is encased in a cylindrical concrete footing. In one embodiment, a stepping surface 800 is attached to cycler post 3001 in such a manner that the stepping surface surrounds the cycler post, and that a child can stand on the stepping surface. Cycler 3000 can be used in many different ways. For example, a child can stand on an attached stepping surface and rotate the handhold assemblies with his/her hands. This is but one of many play options that will be apparent to those skilled in the art. FIG. 39 is a perspective view of another example of a play element that can be incorporated into system 100 . The play element in FIG. 39 is a curved post 3100 . Curved post 3100 includes a post member 3101 . In one embodiment, post member 3101 is constructed from an aluminum tube. In one embodiment, the curved post sits upon crushed rock and is encased in a cylindrical concrete footing. In another embodiment, the curved post includes one or two stepping surfaces 800 attached to post member 3101 . These stepping surfaces could be used to stand on, and elevate from the ground when playing with the curved post. Curved post 3100 can be used in many different ways. For example, a user can hold onto the post and rotate around the post. This is but one of many play options that will be apparent to those skilled in the art. FIG. 40 is an exploded view of another example of a play element that can be incorporated into system 100 . The play element in FIG. 40 is a spring bench 3200 . Spring bench 3200 includes a platform 3201 upon which children can support themselves. In one embodiment of a spring bench, platform 3201 has the approximate shape of two circles joined with one of the circles being larger than the other. Platform 3201 is supported by two spring assemblies 3202 that allow the platform to move in a manner consistent with spring action such as oscillating and dampening. Spring bench 3200 can be used in many different ways. For example, a user can sit on the platform and bounce up-and-down or swing from side-to-side. This is but one of many play options that will be apparent to those skilled in the art. FIG. 41 is a perspective view of an embodiment of an arch-based play system 3300 . System 3300 combines many of the components discussed above. System 3300 includes four arch assemblies 101 , 102 , 103 , 104 , arch clamps 105 (an illustrative two are identified in FIG. 41 ), ball clamps 600 (an illustrative one is identified in FIG. 41 ), spring benches 3200 , a pipe climber 1700 , stepping surfaces 800 (an illustrative two are identified in FIG. 41 ), curved posts 3100 , a climbing net 1500 , a winding slide 1000 , climbing rings 1600 , a cable-disk climber 2200 , and a cable rope climber 1100 . It is worth noting that system 3300 is a composite play structure. A composite play structure is two or more play structures attached or functionally linked, to create one integral unit that provides more than one play activity. System 3300 provides numerous routes in which children can go almost seamlessly from one play element and experience to another. This variety of routes and continuity in play provides an alternate experience to children accustomed to the “post and deck” style of other play systems. An example of a route is that a child could start on the spring benches, travel from the end of the pipe climber towards the center of system, transfer from the pipe climber to the stepping surfaces below, travel from the stepping surfaces to the curved post, travel from the curved post to the climbing net, travel across the climbing net and transfer to the climbing rings, crawl through the climbing rings, and finally slide down the winding slide. Many, many other potential routes exist in the system in which the child can go from one play experience to another without interruption. FIG. 42 is a perspective view of an embodiment of an arch-based play system 3400 . System 3400 includes eight arch assemblies 101 , 102 , 103 , 104 , arch clamps 105 (an illustrative two are identified in FIG. 42 ), a winding slide 1000 , two twisted nets 1400 , a cable-disk climber 2200 , two climbing rings assemblies 1600 , a ringed spinner 2400 , cable rope climber 1100 , spring benches 3200 (an illustrative one is identified in FIG. 42 ), a climbing rings assembly 1600 , two talking posts 2900 , a cycler 3000 , a curved post 3100 , an arched bar structure 1900 , two climbing nets 1500 , a pivoting walk-across 2100 , a rope climbing structure 1800 , and a pipe climber 1700 . Similar to system 3300 , system 3400 provides a wide variety of routes in which to transfer from one play element to the next. Also like in system 3300 , this large variety of routes creates an entirely new play experience for children. An example of a play route in system 3400 is that a child can climb up the arched bar structure, jump onto a curved post, hop to a spring bench, grab onto the adjacent climbing net and work his or herself across, jump on to a talking post, transfer to the spring bench, pull his or herself into the climbing rings and climb through, pull his or herself across the adjacent twisted net, transfer and cross the climbing net, grab onto a pipe climber bar and climb his or herself back down to the ground. It should be noted that systems 3300 and 3400 are only example configurations. The arch-based play system components such as, but not limited to, arch assemblies, arch clamps, ball clamps, and play elements can be used to create many possible configurations of the arch-based design. Further, it should be pointed out that the arch-based system can be implemented in phases. For example, an initial system may only have two arches. An additional two arches can be added subsequently to enable different designs within the environment. Also, any number of arches could be added to the system to enable even more possibilities. The entire system is completely extensible, and the arch assemblies are the core of that extensibility. FIG. 43 is a perspective view of an arch assembly and an imaginary circle. Arch assembly 103 lies in the same plane as the plane created by the three arch clamps 105 . Imaginary circle 3501 is perpendicular to the arch assembly plane. The diameter of the circle is the distance 223 between the first end of the arch assembly 224 and the second end of the arch assembly 225 . Ends 224 and 225 lie on opposing sides of the circumference of circle 3501 . In an embodiment, all arch assemblies in a play system each lie in their own plane and have imaginary circles. The imaginary circles are perpendicular to the plane of their associated arch and have diameters equal to the distance between the first end of the associated arch and the second end of the associate arch. In one embodiment, the imaginary circles formed by arch assemblies in a play system all lie in the same plane. In another embodiment, the imaginary circles formed by arch assemblies in a play system lie in different planes (i.e. arch assembly planes are not perpendicular to the ground). It is worth noting that in an embodiment such as that shown in FIG. 43 , play elements can be attached to an arch assembly and extend beyond the arch assembly's imaginary circle. For example, play element 1700 in FIG. 41 extends beyond the imaginary circles of the arch assemblies 101 and 103 . Similarly in FIG. 41 , play elements 1000 , 1100 , and 2200 extend beyond the imaginary circles of their attached arch assemblies. FIG. 44 is a top view of two arch assemblies and their imaginary circles. Arch assembly 103 has its imaginary circle 3501 , and arch assembly 104 has its imaginary circle 3502 . It is noteworthy that circles 3501 and 3502 overlap (i.e. they share some area in common). The overlapping area is labeled 3503 . In an embodiment, two or more arch assemblies in a play system have imaginary circles that are perpendicular to the arches and the imaginary circles of each arch at least partially overlap such that there is an area common to all imaginary circles. In another embodiment, the imaginary circles are not in the same plane and the overlapping area between the two imaginary circles is more or less a line. FIG. 45 is a top view of four arch assemblies and their imaginary circles. Arch assembly 103 has its imaginary circle 3501 , arch assembly 104 has its imaginary circle 3502 , arch assembly 101 has its imaginary circle 3504 , and arch assembly 102 has its imaginary circle 3505 . It is noteworthy that circles 3501 , 3502 , 3504 , and 3505 overlap (i.e. they share some area in common). This overlapping area is labeled 3506 . FIG. 46 is a perspective view of an arch assembly 104 and an imaginary line 3601 . Line 3601 is tangential to the arch assembly 104 at the ball clamp attachment point 105 . The imaginary line 3601 is not perpendicular to the ground. It is angled. This illustrates that at the attachment point the arch is at an angle other than perpendicular. It is worth noting some of the functionality of some of the features already discussed. Some of the features of embodiments disclosed are arch assemblies having an incomplete circle or oval shape, arch assemblies of different heights, arch assemblies at angles other than parallel or perpendicular to each other, arch assemblies orientated towards each other such that they have overlapping imaginary circles, arch assemblies where attachment points are at arch locations that are not perpendicular to the ground, overlapping arch assemblies, and arch assemblies having end to end distances spaced apart by a distance of at least six feet. All of these features, and others not listed, contribute utility to play systems. Many of the features in addition to having utility when used alone, also contribute additional utility to a system when used in combination. For example, the incomplete circle or oval shapes such as those shown in FIGS. 19-22 utilize the shape to create the layout and size of play environments. The end to end distance of at least six feet allows for play environments such as those shown in FIG. 28 and allows for people to pass under the arch assemblies. The overlapping arch assemblies and overlapping imaginary circles allow for play elements to be located proximate to each other such that a user can pass from one play element to another, and also for play elements to be attached to more than one arch assembly. Arch assemblies with different heights and arches at angles other than perpendicular allow for play elements to be attached to more than one arch and allow for play elements to be located proximate to each other such that a user can pass from one to another. Attachment points at arch assembly portions not perpendicular to the ground allow for better accessibility to play elements by allowing multiple play elements to be located proximate to each other such that a user can easily pass from one play element to another. The not perpendicular attachments also facilitate attaching a play element to more than one arch assembly. Although the arch-based play system has been described with reference to particular embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.

Embodiments of play systems having multiple curved structural members are disclosed. Play systems illustratively include a first quarter of an ellipse, a second quarter of an ellipse, a third quarter of an ellipse, and a fourth quarter of an ellipse. Each ellipse quarter has first and second ends. The first, the second, the third, and the fourth ellipse quarters are oriented approximately vertically relative to a surface such that the first ends of the ellipse quarters contact the surface and the second ends of the ellipse quarters are above the surface. The first ends of the ellipse quarters are optionally spaced further apart from each other than the second ends of the ellipse quarters.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS This application is a divisional of U.S. application Ser. No 10/756,764, filed Jan. 14, 2004, now U.S. Pat. No. 8,118,831, which claims benefit of priority to U.S. Provisional Application No. 60/439,800, filed on Jan. 14, 2003, the contents of which are hereby incorporated by reference. FIELD OF THE INVENTION The present invention relates generally to a closure device for sealing a percutaneous puncture in the wall of a blood vessel, and more particularly to a closure device and a method by which an inner seal is deployed inside a vessel and a locking member is secured outside the vessel, such that bleeding from the percutaneous puncture is prevented. BACKGROUND OF THE INVENTION A system for sealing a percutaneous puncture in a blood vessel can comprise an inner seal which is adapted to be positioned against an inner surface of the vessel wall, and a locking member which is connected to the inner seal by, for example, a filament or a suture, and which is adapted to be positioned against an outer surface of the vessel wall such that the percutaneous puncture is sealed there between. During the phase of insertion, the inner seal is folded inside an introducer tube which is resting in the puncture to provide access to the interior of the blood vessel. Deployment of the inner seal inside the vessel takes place by pushing the inner seal through the tube, out from the distal end opening of the introducer. To ensure proper unfolding of the inner seal, the inner seal has to be deployed some distance away from the puncture hole in the vessel wall before the inner seal is positioned to be securely seated against the inner surface of the vessel wall. When the inner seal has been deployed inside the blood vessel, the introducer is retracted from the puncture to rest with its distal end outside the vessel, in close proximity to the puncture. When, during said retraction, the inner seal has been positioned against the vessel wall to cover the puncture, the locking member is pushed forward through the introducer tube until the locking member is tamped in contact with the outer surface of the vessel wall. To effectuate the different actions described above, inserter tools have been proposed which also accommodate the inner seal and the locking member before the sealing procedure. The devices and procedures for sealing a percutaneous puncture in a blood vessel may be improved with respect to drawbacks connected with the prior art systems: For example, existing systems unconditionally allow tamping of the locking member and provide no verification that the distal end of the introducer is retracted from the puncture before tamping, leading to a possibility of the locking member unintentionally being positioned inside the vessel in case of an incorrect maneuver. Another drawback in existing systems is that two hands typically are required to handle existing tools for deployment of the inner seal, seating the inner seal against the vessel wall, and for tamping of the locking member. SUMMARY OF THE INVENTION The present invention aims to solve at least one of these and other problems. An object of the present invention is to provide a closure device and method by which proper closure and ease of handling are both enhanced upon sealing of a percutaneous puncture in the wall of a blood vessel after a medical treatment or surgery. In one aspect, the present invention aims to provide a closure device by which is eliminated the possibility of the locking member being unintentionally positioned inside the blood vessel. In another aspect, the present invention aims to provide a closure device by which it is ensured that the inner seal is seated against the vessel wall before tamping of the locking member. In a further aspect, the present invention aims to provide a closure device and method by which: deployment of an inner seal inside the vessel; seating the inner seal against the inner side of the vessel wall; and tamping of a locking member such that bleeding through the puncture is prevented, may all be performed in a one-hand operation. Briefly, the present invention provides a closure device for sealing a percutaneous puncture in the wall of a blood vessel, comprising an insertion tool having an actuator which is operable in a first mode for deployment of an inner seal inside the vessel and operable in a second mode for tamping of a locking member outside the vessel, the actuator being arranged to be set into said second operable mode in response to a pulling force acting on a filament connecting the inner seal and the locking member. Preferably, the actuator is controlled by an actuator mechanism that is adapted to disable the actuator until a pulling force acting on the filament causes the actuator to be reset into said second operable mode. According to another preferred embodiment of the present invention, a method for sealing a percutaneous puncture in the wall of a blood vessel may comprise: providing an insertion tool having an actuator which is operable in a first mode for deployment of an inner seal inside the vessel and operable in a second mode for tamping a locking member on an outside of the vessel, the actuator being arranged to be set into the second mode in response to a pulling force acting on a filament connecting the inner seal and the locking member; operating the insertion tool in the first mode; pulling the filament so as to set the actuator in the second mode; and operating the insertion tool in the second mode. Embodiments of the present invention further provide a closure device having an actuator movable between an initial extended position, a first position, and a second position with respect to a housing of the closure device, an inner seal configured to deploy from a distal end of the closure device when the actuator shifts from the initial extended position to the first position, a biasing mechanism configured to urge the actuator from the first position to the second position when a pulling force is applied to the housing, and a locking member configured to deploy from the distal end of the closure device when the actuator shifts from the second position to the first position subsequent to deployment of the inner seal. According to another embodiment of the present invention, a closure device for sealing a blood vessel has an inner seal configured to deploy from the closure device into the blood vessel, a locking member configured to deploy from the closure device to abut an outer surface of the blood vessel, and a filament to connect the inner seal and the locking member. The closure device is configured such that application of a pulling force to the filament, subsequent to deployment of the inner seal, releases a latch mechanism to shift an actuator of the closure device from a first position to a second position and to enable deployment of the locking member. BRIEF DESCRIPTION OF THE DRAWINGS The invention is more closely described below by reference to the drawings, diagrammatically illustrating the new insertion tool and method. In the drawings, FIG. 1 illustrates a blood vessel in which a distal end of an introducer is positioned; FIG. 2 illustrates a guide rod being inserted through the introducer of FIG. 1 ; FIG. 3 illustrates the vessel in which only the guide rod is in place; FIG. 4 illustrates a closure device according to the present invention, the closure device being positioned over the guide rod of FIG. 3 ; FIG. 5 illustrates how the guide rod is removed from the closure device and from the vessel; FIG. 6 is a diagrammatic, cross-sectional view of internal passageways that guide the seal assembly and the guide rod, respectively, in a housing of the closure device; FIG. 7 illustrates how an actuator is pushed into the housing for deployment of an inner seal in a first mode of operation; FIG. 8 illustrates how the closure device is retracted until the inner seal is in contact with the vessel wall; FIG. 9 illustrates how the actuator is pushed into the housing for tamping of a locking member in a second mode of operation; FIG. 10 illustrates the closure device after completion of the sealing operation; FIG. 11 is an exploded view showing the major components of one embodiment of the closure device according to the present invention; FIG. 12 is a partially broken away elevation view of a seal assembly and associated elements of the closure device; FIG. 13 a is a partially broken away elevation view of a slider, incorporated in the closure device; FIG. 13 b is a top view of the slider of FIG. 13 a; FIG. 13 c shows the proximal end of the slider; FIG. 13 d shows the distal end of the slider; FIG. 14 a is a longitudinal section, part of which is laterally displaced, through section ( 14 a )-( 14 a ) of FIG. 14 b of an actuator incorporated in the closure device; FIG. 14 b is a sectional top view of the actuator of FIG. 14 a through section ( 14 b )-( 14 b ); FIG. 14 c is an elevation view showing the distal end of the actuator; FIG. 14 d is a partially broken away sectional view showing the slider and the actuator in a first relative position, realizing a first mode of operation; FIG. 14 e is a partially broken away sectional view showing the slider and the actuator in a second relative position, realizing a second mode of operation; FIG. 15 a is a longitudinal section through section ( 15 a )-( 15 a ) of FIG. 15 c of a sleeve, incorporated in the closure device; FIG. 15 b is a sectional top view through section ( 15 b )-( 15 b ) of FIG. 15 c of the sleeve; FIG. 15 c is an elevation view showing the proximal end of the sleeve. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS A closure device for sealing a percutaneous puncture in a blood vessel is generally referred to by reference numeral 1 in the drawings. In FIGS. 4-10 , the closure device 1 is diagrammatically shown in different operative positions illustrating the procedural steps of the sealing operation. In FIGS. 11-15 , the structure and operation of an actuator mechanism in the closure device 1 is illustrated and explained, by way of example. FIG. 1 illustrates an introducer 600 whose distal end portion is introduced into a blood vessel 2 and whose proximal portion extends out from the skin of a patient. Presumably, a medical operation has been performed via the introducer 600 , and the puncture hole through the wall 3 of the blood vessel is now to be closed. In order to replace the introducer 600 with a closure device 1 according to the present invention, a guide rod 4 may be inserted through the introducer 600 as is shown in FIG. 2 . In FIG. 3 the introducer 600 has been removed, leaving only the guide rod 4 in place. An advantage achieved by the use of a guide rod is that the diameter of the guide rod is larger than the diameter of a guide wire, e.g., which in the case of an artery results in less blood flowing from the artery, and the necessity for a manual external compression may thereby be avoided. FIG. 4 shows a closure device 1 according to the present invention, threaded over the guide rod 4 . This is in contrast to insertion tools that are adapted to be connected to an existing introducer 600 . The present closure device 1 is therefore independent of the type, e.g., diameter or length, of the introducer 600 that was previously inserted into the vessel. When the correct positioning of the closure device 1 has been established, the guide rod 4 is removed as is illustrated in FIGS. 5 and 6 . FIG. 6 shows, diagrammatically, a cross-section of a forward portion of the housing 100 of the closure device 1 . From the drawing it can be seen that a first passageway, in which seal assembly 500 is positioned, connects to a second passageway in which the guide rod 4 moves. Here it should be noted that it is possible to let the first and second passageways switch places, such that the guide rod 400 , which is flexible, is inserted through the first passageway. It is also conceivable to have two passageways that both are slightly bent. Two passageways can also connect to a straight passageway, which gives a configuration having the shape of the letter Y. As illustrated in FIG. 7 , an actuator 200 is depressed into the proximal end of the closure device housing 100 . When the distal end of the device 1 is positioned in the blood vessel, the guide rod 4 is removed, and the operator pushes the actuator 200 towards an end position provided in the housing 100 . The actuator 200 is operatively associated, in a first relative position, with a sliding member 300 that carries a tamping tube 505 and a pusher 506 , the latter detachably carrying an inner seal 501 by its distal end and pushing the inner seal 501 out from the closure device 1 to be deployed inside the vessel. This step completes a first mode of operation of the actuator mechanism. One embodiment of the actuator mechanism, which is accommodated in the housing 100 of the closure device 1 , is diagrammatically illustrated and further explained below with reference to FIGS. 11-15 . An important feature of the mechanism is that the locking member 502 , which is carried behind the inner seal 501 on a filament 503 , cannot be pushed out from the closure device 1 unintentionally when the actuator 200 has been pushed into its end position. An erroneous tamping of the locking member 502 inside the vessel is thereby prevented. The mechanism 200 comprises a spring member 207 generating a biasing force acting on the actuator as the actuator is pushed into the housing 100 . When the actuator 200 reaches its end position, a snap lock connection temporarily arrests the actuator in this end position. Referring now to FIG. 8 , in the next step of the sealing operation the housing 100 is manually retracted, i.e., the housing 100 is pulled in the proximal direction until the inner seal 501 is seated over the puncture in contact with the inner surface of the vessel wall 3 , while simultaneously the distal end of the closure device 1 is retracted from the puncture. During retraction of the closure device 1 , the pulling force is carried by the filament 503 which is arrested by its distal end being attached to the inner seal 501 and by its proximal end being connected to the sliding member 300 . The filament 503 thus prevents the sliding member 300 from moving in the proximal direction, causing the sliding member 300 to be displaced relative to the actuator 200 . By means of a cam surface provided on the sliding member 300 , the snap connection that arrests the actuator 200 is disengaged in response to the relative displacement between the retracting actuator 200 and the stationary sliding member 300 . As the snap connection is disengaged, the biasing spring 207 pushes the actuator 200 back to a tamping position wherein the actuator 200 is again operatively associated with the sliding member 300 , now in a second relative position. Furthermore, during this retraction of the housing 100 , the proximal end of the pusher is disconnected from engagement with the sliding member 300 , and a subsequent second forward motion of the actuator 200 will have no effect on the pusher 506 . In the tamping operation the actuator 200 acts on the sliding member 300 , the tamping tube 505 and the locking member. FIG. 9 illustrates the actions caused by a second forward motion of the actuator 200 . When the actuator 200 this second time is pushed towards its end position in the housing 100 , the actuator 200 pushes on the sliding member 300 which, via the tamping tube 505 , pushes the locking member forward and into a locking position against the outer surface of the vessel wall 3 , as is illustrated in FIG. 9 . This step completes the second mode of operation of the actuator mechanism. The filament 503 runs through the locking member 502 . In the tamped position, the filament 503 secures the locking member 502 by means of frictional engagement provided from a distal portion of the filament 503 , the portion having an enlarged dimension or diameter. The proximal end of the filament 503 is attached to the sliding member 300 through a sliding connection. In the first mode, when the actuator 200 and sliding member 300 are pushed forward for deployment of the inner seal 501 , the filament 503 is tensioned by the pusher 506 gripping the inner seal 501 by its distal end. In the second mode, as the actuator 200 and sliding member 300 are pushed forward for tamping the locking member 502 , the pusher 506 is inactive and the filament 503 is arrested by a member which is stationary relative to the sliding member 300 and which maintains a tension of the filament 503 . At the very end of the forward motion, the proximal end of the filament 503 is released from the sliding member 300 by the action of the stationary member. Here it should be noted that one person can perform the closure using one hand only throughout the whole sealing procedure. The housing 100 and its associated components can now be removed and disposed of, thereby leaving only the inner seal 501 , the locking member 502 and the filament 503 in place, as is illustrated in FIG. 10 . Cutting the filament 503 completes the sealing operation. As will be more fully understood from the following description of the device, the present invention discloses a method for sealing a percutaneous puncture in the wall of a blood vessel, comprising the step of providing an insertion tool having an actuator 200 which is operable in a first mode for deployment of an inner seal 501 inside the vessel 2 and operable in a second mode for tamping of a locking member 502 on the outside of the vessel 2 , wherein operation of the actuator 200 for tamping the locking member 502 is enabled through the step of applying a pulling force to act on a filament 503 , connecting the inner seal 501 and the locking member 502 , for setting the actuator 200 into the second operable mode. Preferably, the step of operating the actuator 200 for deployment of the inner seal 501 disables operation of the actuator 200 for tamping the locking member 502 , until the step of applying a pulling force to act on the filament 503 resets the actuator 200 into the second operable mode. In the present description of an illustrated embodiment, “distal” refers to the left hand side and “proximal” refers to the right hand side of the drawings of FIGS. 11-15 . Also, the expressions “top”, “bottom”, “horizontal” and “vertical” refer entirely to the orientation shown in the drawings, and is no indication of the actual orientation of the closure device in practice. With reference to FIG. 11 , the closure device 1 comprises as its major components: a housing 100 (outlined in dash-dot lines), and an actuator 200 , a slider 300 , a sleeve 400 and a seal assembly 500 , all supported in the housing 100 . Basically, the sleeve 400 is telescopically received in the housing 100 , the actuator 200 is telescopically received in the sleeve 400 , the seal assembly 500 is operatively connected to the slider 300 , and the slider 300 is operatively engaged by the actuator 200 . The slider 300 is guided for longitudinal displacement relative to the actuator 200 between first and second relative positions, in which the actuator 200 operatively engages the slider 300 to be brought into the movement of the actuator 200 . The actuator 200 is guided for longitudinal movement relative to the sleeve 400 , from an extended storage or idle position to a partially overlapping operable position from where the actuator 200 is further advanced to an end position for deployment of the inner seal 501 in the first mode, and for tamping the locking member 502 in the second mode of operation. The sleeve 400 is accommodated in the housing 100 and guided therein for longitudinal movement, from an extended idle position to a fully inserted operative position. Advantageously, the housing 100 , sleeve 400 and actuator 200 are arranged about a common longitudinal axis. The housing, the sleeve and the actuator, as well as the slider, may be of any suitable sectional profile, such as circular, or they may for example have an orthogonal section such as the illustrated embodiment of a closure device 1 according to the invention. As an assembly, these components provide a tool for insertion of the sealing components such as the inner seal 501 , the filament 503 and the locking member 502 . The housing 100 is associated with an insertion tube 101 , connecting to the distal end of the housing via a forward house portion 102 (as seen in the direction of insertion). Insertion tube 101 and house portion 102 may be integral parts of the housing 100 . When inserted by its distal end through the puncture, the insertion tube 101 communicates the blood vessel with first and second passageways formed in the forward house portion 102 (as shown in FIG. 6 ), one of which is designed to receive a guide rod 4 that controls the insertion tube 101 during location in the blood vessel, and the other passageway designed for insertion of the inner seal 501 and locking member 502 upon sealing of the puncture. These passageways converge into the insertion tube 101 . Advantageously, the housing 100 is formed with indication means providing a verification that a flow communication has been established with the blood vessel, via the distal end of housing 100 /insertion tube 101 . Such a means will be known to one of ordinary skill in the art. With reference to FIG. 12 , the seal assembly 500 comprises the inner seal 501 and the locking member 502 , the inner seal 501 being anchored in the distal end of the suture or filament 503 running through the locking member 502 . The locking member 502 is spaced behind the inner seal 501 , on the proximal side of an end portion 504 of the filament 503 having increased cross-sectional dimension, providing a frictional engagement with the locking member 502 in its tamped (advanced) position on the filament 503 . In a ready-to-use condition, the inner seal 501 and locking member 502 both lie encapsulated in the forward house portion 102 (diagrammatically illustrated in FIG. 11 ). The filament 503 runs through the tamping tube 505 , together with the pusher 506 . The filament 503 and the pusher 506 both reach out beyond the distal end of the tamping tube 505 , the pusher 506 by its distal end detachably gripping the inner seal 501 , and the locking member 502 freely supported on the filament 503 outside the distal end of the tamping tube 505 . Also, the filament and the pusher both reach out from the proximal end of the tamping tube 505 . The proximal ends of the filament 503 , the pusher 506 and the tamping tube 505 are all supported in the slider 300 , as will be explained below with reference also to FIGS. 13 a - 13 d. Referring now to FIGS. 13 a and 13 b , the slider 300 is an elongate four-sided body having an orthogonal section, dimensioned to be accommodated in the actuator 200 for longitudinal movement therewith, and guided in the actuator 200 for longitudinal displacement relative thereto. In FIGS. 13 c - 13 d , the slider 300 has opposed, vertical side walls 301 , 302 connecting a horizontal top plane 303 with a horizontal bottom plane 304 . Preferably, the longitudinal margins connecting the walls are chamfered in order to facilitate a sliding displacement free from jamming in the actuator 200 . The tamping tube 505 connects to the distal end of the slider 300 , the proximal end of the tamping tube 505 being received in a recess 305 , mouthing in the distal end of the slider 300 . In one side wall 301 of the slider 300 , the recess 305 opens laterally towards the exterior, the opening forming a slot 306 that connects the recess 305 with a clearance 307 through the side wall 301 . On the interior of side wall 301 , the slot 306 proceeds rectilinearly from the clearance 307 to the proximal end of slider 300 . A corresponding slot 306 ′ is formed on the interior of the opposite side wall 302 . The slots 306 , 306 ′ are dimensioned to receive and to guide the pusher 506 , the proximal end 507 of the pusher being bent transversely to reach across the interior of slider 300 for a sliding engagement with the two slots 306 , 306 ′. The filament 503 is detachably connected to the slider 300 through a sliding connection. The proximal end of the filament 503 is arrested in the slider 300 by being looped around a longitudinal bar 308 , cut out from the opposite side wall 302 . The bar 308 extends from a distal portion of the slider 300 , and terminates with a free end in a proximal portion of the slider 300 . The filament 503 runs, under a slight tension, from the bar 308 across the interior of slider 300 , via the clearance 307 into the slot 306 and further through the tamping tube 505 to the inner seal 501 which is supported in the distal end of the pusher 506 . The tension of the filament 503 is provided by the pusher 506 , the transverse portion in the proximal end 507 of the pusher being arrested in a seat 309 formed in a latch 310 that rises from the bottom 304 of slider 300 , and the distal end of the pusher 506 being detachably connected to the inner seal 501 which is attached to the distal end of the filament 503 . The length of the pusher 506 is determined with respect to the length of the filament 503 to provide a slight bias of the pusher 506 , sufficient for tensioning the filament 503 as long as the proximal end of the pusher 506 is arrested by the latch 310 , and the proximal end of the filament 503 is looped around the bar 308 . The seat 309 provides a snap lock connection with the pusher 506 , by the latch 310 being depressible towards the bottom 304 of slider 300 . Depression of the latch 310 causes the pusher 506 to be released from the seat 309 and free to slide in the slots 306 , 306 ′, towards the proximal end of the slider 300 . A heel 311 , facing the proximal end of slider 300 , is formed in the terminal end of an arm 312 rising from the bottom 304 of the slider 300 . Similar to the latch 310 , the arm 312 is depressible towards the bottom 304 of slider 300 . However, for reasons that will be explained further on, the arm 312 is flexible and able to return to an operative position shown in the drawings. Advantageously, the latch 310 and the arm 312 are both flexible and formed integrally with the slider 300 , made for example of a synthetic material such as a polymer material. The latch 310 and the arm 312 are both formed with ramp surfaces 313 , 314 interacting with a cam 210 which is stationary in the actuator 200 . When assembled, the cam 210 reaches through the open top plane 303 to be received in the interior of slider 300 as will be further explained with reference to FIGS. 14 a - e. In the illustrated embodiment of FIGS. 14 a - e , the actuator 200 is an elongate, hollow, four-sided body having an orthogonal section, dimensioned to receive the slider 300 for longitudinal movement therewith, and guiding the slider 300 for longitudinal displacement relative thereto. The actuator 200 is formed with opposed, vertical side walls 201 , 202 connecting a horizontal top plane 203 with a horizontal bottom plane 204 . Preferably, the longitudinal margins connecting the walls are chamfered in order to facilitate a sliding movement free from jamming in the sleeve 400 . With reference to FIGS. 14 a - 14 c , the actuator 200 is a two-piece element hinged together along one side thereof. A snap lock engagement may be formed on the opposite side for closing the actuator body. The interior of actuator 200 is divided into a first longitudinal chamber 205 formed to receive the slider 300 , and a second longitudinal chamber 206 formed to receive a compressible spring 207 (shown diagrammatically through dash-dot lines in FIGS. 14 b , 14 c ). Both chambers, separated by a longitudinal partition wall 208 , open in the distal end of actuator 200 . The proximal end thereof is closed, carrying a push-button 209 . Depending from the interior of top plane 203 , a cam 210 reaches down into the chamber 205 . In the assembled position, the cam 210 is received through the open top plane 303 of the slider 300 to a depth wherein the cam 210 is operative to engage and depress the ramp surfaces 313 and 314 in succession, i.e., first depressing the latch 310 and then the arm 312 , when the slider 300 is displaced relative to the actuator 200 . In the first mode of operation for deployment of the inner seal 501 , such as in FIGS. 7 and 14 d , the proximal end of the slider 300 abuts the proximal push-button end of actuator 200 , the actuator 200 thus pushing the slider 300 forward (towards the distal end) in a first relative position between slider and actuator. In the second mode of operation for tamping the locking member 502 , such as in FIGS. 9 and 14 e , the cam 210 engages the heel 311 and the actuator 200 thus pushes the slider 200 in a second, advanced position relative to the actuator 200 . The displacement of the slider 300 , from said first to said second position relative to the actuator 200 , is caused by applying a pulling force upon retraction of the housing 100 in order to position the inner seal 501 over the puncture and in order to retract the distal end of the housing/insertion tube (see FIG. 8 ). During retraction, the slider 300 will remain stationary relative to the inner seal 501 , connected therewith through the filament 503 . A pulling force, applied to the actuator 200 via the housing 100 and the sleeve 400 , and thus acting on/carried by the filament 503 , causes ejection of the spring biased actuator 200 , and brings the cam 210 to engage the ramp on latch 310 which is depressed by the moving cam to release the pusher 506 from the seat 309 . Further motion of the actuator cam 210 will bring the pusher 506 along, the transverse portion 507 of the pusher being caught by a hook 211 that is formed on the cam 210 . Next, the cam 210 engages the ramp 314 on arm 312 , which is depressed to let the cam 210 pass to the proximal side of the heel 311 . Due to the flexibility of arm 312 , the arm returns to its original position wherein the heel 311 projects into the path of the cam 210 , thus arresting the slider 300 in a second and advanced position relative to the actuator 200 . Simultaneously, the proximal end of the pusher 506 leaves the guiding slots 306 , 306 ′ formed on the interior of the slider walls. As the pusher 506 is released from engagement with the seat 309 and pulled backwards by the cam-and-hook formation 210 , 211 , the distal end of the pusher 506 is concurrently disconnected from the inner seal 501 . When the proximal end of the pusher 506 leaves the slots 306 , 306 ′ in the slider walls, the distal end of the pusher 506 is also fully retracted into the distal end of the tamping tube 505 . The relative displacement between the actuator 200 and the slider 300 is thus initiated by the pulling force acting on the filament 503 , and is then driven by the compressible spring 207 as will be explained below. With reference to FIGS. 15 a - c , the sleeve 400 is an elongate, hollow, four-sided body having an orthogonal section, dimensioned to receive and guide the actuator 200 for longitudinal movement relative to the sleeve 400 . The sleeve 400 is formed with opposed, vertical side walls 401 , 402 connecting a horizontal top plane 403 with a horizontal bottom plane 404 . Preferably, the longitudinal margins connecting the walls are chamfered in order to facilitate a jam free movement relative to the housing 100 , accommodating the sleeve 400 . The sleeve 400 has an open proximal end receiving the actuator 200 , and the distal end of the sleeve 400 being closed by an end wall 405 . An opening 406 through the end wall 405 communicates with the passage through the forward portion 102 of the housing 100 , guiding the seal assembly 500 into the insertion tube 101 of the closure device 1 . A rod 407 projects longitudinally through the sleeve 400 , from the end wall 405 towards the proximal end. In the assembly, the rod 407 projects into the chamber 206 of the actuator 200 to support the spring 207 , in this case a coiled spring 207 , acting between the end wall 405 of the sleeve and the proximal or push-button end 209 of the actuator 200 , and being compressed when the actuator 200 is depressed into the sleeve 400 . Also projecting from the end wall 405 is a beam 408 , running in parallel with the rod 407 and aligned with the open interior of the slider 300 in the assembled position. The beam 408 runs with a clearance from the interior of top plane 403 , substantially corresponding to a wall thickness in the top plane 203 of actuator 200 . The beam 408 carries a latch 409 which is depressible towards the bottom plane 404 of the sleeve 400 . The latch 409 is flexible to engage a slot 212 (see FIG. 14 a ), provided in the top plane 203 of the actuator 200 when the actuator is fully depressed into the sleeve 400 for deployment of the inner seal 501 . The slot 212 and latch 409 provide a snap lock connection, the latch 409 being operative for retaining, temporarily as will be explained below, the actuator 200 with its distal end abutting the end wall 405 of the sleeve 400 . In this end position of the actuator 200 , which terminates the first mode of operation in a definite stop from where the actuator 200 is prevented from further movement in the distal direction, the proximal end 410 of the beam 408 is received in the distal end of the slider 300 which is engaged by the actuator 200 in said first relative position. Reset of the actuator 200 will be described as follows. The latch 409 is associated with a ramp surface 411 which is laterally and vertically offset from the latch 409 and aligned to be operatively engaged by a cam 315 , provided in the distal end of the slider 300 (see FIGS. 13 a - d ). Upon retraction of the insertion tool, the cam 315 on the slider 300 (which remains stationary) acts on the ramp surface 411 to depress the latch 409 , which is then disengaged from the slot 212 . The actuator 200 is thus disengaged from the snap lock connection 212 , 409 to be ejected by action of the spring 207 , the spring driving the actuator 200 in the proximal direction relative to the sleeve 400 and relative to the stationary slider 300 . The action of the spring 207 causes the release of the pusher 506 , and resets the actuator 200 into a position from where the actuator 200 is operable and enabled for tamping the locking member 502 . The spring actuated ejection of the actuator 200 is limited through a flexible latch 213 , provided in a distal end portion of the actuator ( FIG. 14 c ), snapping into engagement with a slot 412 provided on the sleeve 400 . The latch 213 is formed with a ramp surface facing a distal margin of the slot 412 , and a transverse surface engaging a proximal margin of the slot 412 . From this arrested position the actuator 200 is operable to be depressed in the distal direction, but is however prevented from further movement in the proximal direction. Depression of the actuator 200 into the sleeve 400 will bring the slider 300 in the movement of the actuator 200 , the cam 210 of the actuator engaging the heel 311 of the slider 300 in the second, advanced position relative to the actuator 200 . Release of the filament 503 will be described as follows. When the actuator 200 from this position is depressed into the sleeve 400 in the second mode of operation, the slider 300 is advanced in a forward or distal portion of the actuator 200 . In this movement, the beam 408 which is stationary on the sleeve 400 , moves longitudinally through the interior of the slider 300 . The filament 503 which is looped around the bar 308 and crossing the interior of the slider 300 , is then captured by the proximal end 410 of the beam 408 and caused thereby to slide towards the proximal end of the bar 308 . Accordingly, the filament 503 remains stationary while the actuator 200 , slider 300 and tamping tube 505 are advanced for slipping the locking member 502 into frictional engagement with the distal portion 504 of the filament 503 . At the end of the tamping operation the filament loop has reached the proximal end of the bar 308 , from where it is slipped off by action of the beam 408 , the filament 503 thus being released from the slider 300 . Obviously, all structures involved in the tamping operation are dimensioned with respect to structural lengths and lengths of movement to allow release of the filament 503 as the locking member has reached its final position on the filament 503 , tamped against the outside of the vessel wall 3 . Release of the filament 503 terminates the tamping operation, and the insertion tool can be removed from the patient. The illustrated embodiment is one example of realization of the invention. Modifications to the detailed structure and design of components are possible without changing the basic solution, defined by the claims. Instead of one integral actuator, e.g., a first actuator may be adapted for deployment of the inner seal 501 and a second actuator being adapted for tamping the locking member 502 . In such case the slider 300 would be arranged to be disengaged from the first actuator and brought into engagement with the second actuator in response to a pulling force acting through the filament 503 , while simultaneously the second actuator is set into an operable condition. Also, instead of being arranged about a common longitudinal axis as illustrated, the actuator 200 , sleeve 400 and slider 300 may be of any conceivable shape as long as it is ensured that the first mode of operation terminates in a definite stop from where the tamping tube 505 and locking member 502 are prevented from further movement in the distal direction until the second mode of operation is enabled in response to a pulling force being applied to act on the filament 503 . A central feature of the new closure device 1 is, accordingly, that an actuator 200 in a first mode is operable for deployment of an inner seal 501 , and is then reset into a second mode wherein the actuator 200 is operable for tamping a locking member 502 . Reset of the actuator 200 is accomplished by applying a pulling force to act on the filament 503 that connects the inner seal 501 and the locking member 502 . Thus, deployment of the inner seal 501 , enabling of a second operable mode and tamping of the locking member 502 may all be performed in a one-hand operation. Also, an erroneous positioning of the locking member 502 inside the blood vessel is prevented by the actuator 200 preferably being disabled until a pulling force acting on the filament 503 causes the actuator 200 to be reset into an operable condition. A proper closure of the percutaneous puncture and ease of handling are thus both conceivably enhanced through a closure device as disclosed by the present invention.

A closure device includes an actuator movable between an initial extended position, a first position, and a second position with respect to a housing of the closure device, an inner seal configured to deploy from a distal end of the closure device when the actuator shifts from the initial extended position to the first position, a biasing mechanism configured to urge the actuator from the first position to the second position when a first pulling force is applied to the housing, and a locking member configured to deploy from the distal end of the closure device when the actuator shifts from the second position to the first position subsequent to deployment of the inner seal.

CROSS REFERENCE TO RELATED APPLICATIONS [0001] The present application is a US Bypass Continuation of International Application PCT/EP2011/057908 filed May 17, 2011. This application claims the benefit under 35 USC 119 of German patent application DE 10 2010 020 727.6 filed in Germany on May 17, 2010. International Application PCT/EP2011/057908 is hereby incorporated by reference in its entirety. TECHNICAL FIELD [0002] The invention concerns a filter for filtering fluids, in particular fuel or oil, in particular of a motor vehicle, including a housing which is comprised of at least two housing parts, and a filter element which is attached by means of a releasable detent connection in one of the housing parts and acts as a fastening housing part for the filter element, wherein the detent connection includes at least two interacting detent components, and one of the detent components is connected with the filter element and one of the detent components with the fastening housing part. BACKGROUND OF THE INVENTION [0003] EP 0 959 978 B1 discloses a filter which includes a housing which, in turn, is comprised of two screwed-together housing parts. For producing a reliable detent connection between filter element and a cover housing part, a recess is provided in the area of the cover housing part. This recess has different functional areas, namely a locking area, a retaining area, a translation area and an insertion/removal area which are necessary for effecting or for releasing the detent connection. Detent means of the filter element can be moved between the functional areas by relative rotations between the filter element and the cover housing part. [0000] There remains a need in the art for a filter element, a fastening housing part, and a releasable detent connection configured in such a way that the filter element can be inserted into and removed from the filter housing in an easier and more reliable way and further, when exchanging the filter element, no fluid from the filter should reach uncontrollably the surroundings, if possible. SUMMARY OF THE INVENTION [0004] An object of the present invention is to provide a filter for filtering fluids, in particular fuel or oil, in particular of a motor vehicle, including a housing which is includes of at least two housing parts, and a filter element which is attached by means of a releasable detent connection in one of the housing parts and acts as a fastening housing part for the filter element, wherein the detent connection includes at least two interacting detent components, and one of the detent components is connected with the filter element and one of the detent components with the fastening housing part and at least one of the detent components includes at least one detent means and one of the detent components a recess matching the detent means, in which recess the detent means hooks in a bayonet-like manner, and wherein the recess may include at least one or more of the following limitations: a locking area for receiving the detent means while the housing parts are connected, a retaining area for receiving the detent means during opening of the filter housing, a translation area for releasing the detent means in the recess, and an insertion/removal area for resistance-free joining and separating the detent means and the recess. [0009] Another object of the invention is to provide a filter element of a filter which includes a detent component that is adapted to form with a detent component, which is connected with a fastening housing part of a filter housing, a releasable detent connection, wherein one of the detent components includes at least one detent means and one of the detent components a recess matching the detent means, in which recess the detent means is hooked in a bayonet-like manner. [0010] A further object of the invention is to present a fastening housing part of a filter housing of a filter which includes a detent component, this is adapted to form with a detent component, which is connected with a filter element of the filter, a releasable detent connection, wherein at least one of the detent components includes at least one detent means and one of the detent components a recess matching the detent means, in which recess the detent means is hooked in a bayonet-like manner. [0011] Additionally, objects of the invention concern a telescopic switching element of a switching device of a releasable detent connection for attachment of a filter element in a fastening housing part of a filter for filtering fluids, in particular fuel or oil, in particular of a motor vehicle. [0012] The above objects are solved according to the invention in that a switching device includes at least two corresponding switching components and one of the switching components is connected with the filter element and one of the switching components with the fastening housing part, and one of the switching components includes at least one switching lug that extends radially relative to a rotation/insertion axis of the filter and one of the switching components includes a switching guide for guiding the switching lug, so that the switching guide leads the switching lug upon an impulse-like relative axial movement of the filter element in a direction toward the fastening housing part and thereby effects a rotation of the filter element relative to the fastening housing part around the rotation/insertion axis for moving the detent means from the insertion/removal area into the locking area or from the retaining area into the insertion/removal area, depending on the position of the detent means in the recess before the axial movement is effected. [0013] According to the invention, the detent connection is activated and deactivated with the switching device. For this purpose, an impulse-like axial movement of the filter element relative to the fastening housing part is converted into a relative rotation for moving the detent means in the areas of the recess. Such impulse-like axial movements can be generated preferably, with the filter housing being open, simply with one hand by hitting with the free end face of the filter element against a solid body, in particular a tabletop or a drain pan, without this requiring that the possibly fluid-contaminated filter element be directly touched. For assembling the filter, the filter element is inserted into the filter housing part. The switching lug is rotated with the switching device by a first impulse-like axial movement of the filter element from the insertion/removal area into the locking area. The filter element is thus secured in the fastening housing part, even when the latter is pointing with its open side in downward direction. The fastening housing part with the filter element can thus be mounted in a simple and reliable way even at sites that are difficult to access, especially hidden sites, in an engine compartment, on an appropriate system-mounted housing part. For dismantling, the fastening housing part with the filter element is separated from the system-mounted housing part. When doing so, the detent means is rotated across the translation area automatically into the retaining area of the recess so that the filter element is retained in the fastening housing part. The fastening housing part can then be separated safely, without the filter element falling out, with one hand from the system-mounted housing part and, with the opening pointing in downward direction, can be put down to allow the residual fluid still contained in the fastening housing part to drain. Because the detent means are still locked within the retaining area, the filter element cannot fall out uncontrollably when carrying out a one-handed turning of the fastening housing part. For separating, another impulse-like axial movement is exerted on the filter element by means of which, with the aid of the switching device, the detent means is rotated from the retaining area into the insertion/removal area. Then the filter element is separated without resistance from the fastening housing part. The switching device can be located advantageously at the center of an end face of the filter element in order to save space. The detent device can be simply arranged on the circumferential side on the same or the other end face of the filter element. In reverse, the switching device can be also arranged on the circumferential side of one of the end faces and the detent device at the center of one of the end faces of the filter element. The detent means, in particular in the form of a detent lug, can be advantageously connected directly or by means of a detent ring or a similar connecting part on the filter element. The recess can be realized at an elevated part on the inner wall side of the fastening housing part. In this manner, the detent means, which is more susceptible to wear than the recesses, can be exchanged together with the filter element. The switching lug can be realized on a separate component, in particular a stationary cylinder or a dipping cylinder of a telescopic switching element. This component can be fastened releasably, in particular with a screw connection, to the fastening housing part so that it can be simply exchanged, in particular in case of wear. The component can thus be retrofitted also in existing fastening housing parts. The component can be prefabricated as a module and thus be mounted easily. The switching guide can be simply realized in particular in an axial recess of an end disc of the filter element. Since the detent connection and the switching device are matched to each other, it is prevented that a filter element can be mounted without a detent connection that is not matched to the fastening housing part or with a faulty detent connection and/or switching device. In this manner, interferences with the filter function, caused in particular by wrong assembly, are prevented. [0014] Advantageously, the switching guide may be realized as a switching sleeve, which includes a succession of progressing switching teeth or angled guide members in circumferential direction. A switching sleeve with progressing switching teeth or angled guide members can be simply produced. In particular such switching guide can be simply shaped from plastic or cut, milled or punched from metal. [0015] In another advantageous aspect of the invention, the switching device may comprise at least one elastic element, in particular a spiral compression spring, for realizing a pre-tension between the fastening housing part and the filter element. A restoring force, in particular a spring force, can thus be generated between the fastening housing part and the filter element. For connecting the fastening housing part with the other housing part, the filter element can be pushed against the elastic element into the fastening housing part in axial direction. The thus generated restoring force causes when changing, in particular releasing, the detent connection, such that the filter element is pressed in axial direction out of the fastening housing part. The filter element in this way releases in the fastening housing part a volume into which the residual fluid which has remained in the filter element can flow in. In this manner it is prevented that fluid reaches the surroundings when exchanging the filter element. The elastic element is matched to the filter element and the fastening housing part, so that an installation of the filter element is not possible without the matching elastic element. In this manner, malfunctions of the filter are prevented. [0016] One of the switching components may advantageously comprise a telescopic switching element with a stationary cylinder and a dipping cylinder between which the elastic element is acting and which are inserted into each other, with generation of a pre-tension of the elastic element, for inserting the filter element into the fastening housing part. In a telescopic switching element, the stationary cylinder and the dipping cylinder are guided stably relatively to each other when carrying out axial movements. [0017] Further, the telescopic switching element may comprise advantageously a releasable locking mechanism which is activated in the basic state and blocks pushing together the telescopic switching element, and the other switching component can comprise at least one release element which is matched to the locking mechanism such that the release element deactivates the locking mechanism when joining the telescopic switching element and the other switching component. The release element and the locking mechanism interact according to the lock-and-key principle wherein one of the components is connected with the filter element and the other component with the fastening housing part. To release the locking mechanism, the matching release element is necessary; otherwise, the extended telescopic switching element prevents that the filter element can be inserted completely into the fastening housing part. Then the filter element projects from the fastening housing part and this can be easily recognized from outside. In this manner, it is prevented that a filter element is employed that does not ting the filter. [0018] In another advantageous aspect of the invention, a ring seal may be fastened in particular to an end face of the filter element for sealing relative to the filter housing and is adjustable axially, with respect to the rotation/insertion axis relative to the filter element. The ring seal may have advantageously a half moon-shaped profile so that the ring seal is curved on the radial exterior side and can optimally rest tightly against an appropriate sealing surface of the filter housing. In radial direction inwardly, the ring seal may be flat and, in order to save space, can rest against a suitable support ring which may carry and support the ring seal. The support ring may be connected with a simple guide mechanism to the filter element so as to be slideable relative thereto in axial direction. By means of the slideable ring seal the filter element on this end face is supported floatingly in the filter housing. The ring seal can be moved advantageously in particular at the time of opening and closing the filter housing. The ring seal can be simply exchanged together with the filter element. Advantageously, the slideable ring seal can be arranged at the end face that is facing away from the bottom of the fastening housing part outside of the fastening housing part and seal relative to the inside of the other, preferably system-mounted, housing part. When separating the fastening housing part from the other housing part, the ring seal can still seal up to the point of reaching its movement limit relative to the other housing part in order to prevent that fluid from the other housing part reaches the surroundings. When the ring seal is so designed that it seals relative to the other housing part, the wall thickness of the fastening housing part can be reduced advantageously. Moreover, by means of the moveable ring seal it can be prevented that a faulty ring seal or a ring seal that does not fit the filter housing or a filter element with a faulty or non-fitting ring seal is used so that disturbances of the filter function can be prevented in a simple way. [0019] In the present invention, the technical object is solved according to the invention further in that the filter element includes a switching component that is adapted to interact with a switching component of the fastening housing part in such a way that a switching device embodied with the switching components, upon an impulse-like relative axial movement of the filter element in a direction toward the fastening housing part, causes a rotation of the filter element relative to the fastening housing part around the rotation/insertion axis of the filter in order to move the detent means in the recess, depending on the position of the detent means in the recess before effecting the axial movement. The advantages enumerated above in connection with the filter according to the invention extend likewise to the filter element. [0020] In an advantageous aspect of the invention, a ring seal may be provided at an end face of the filter element for sealing relative to the filter housing, wherein the ring seal is slideable axially relative to the filter element. In this manner, the filter element can be supported floatingly in the filter housing. Further, the assembly and disassembly can be facilitated; in particular escape of fluid into the surroundings is prevented when dismantling. The ring seal can be exchanged simply together with the filter element. [0021] The filter element may include advantageously at least one release element that is suited to deactivate a releasable locking mechanism of a telescopic switching element of the switching device upon installation of the filter element into the fastening housing part. The advantages mentioned above in connection with the release element of the filter according to the invention extend likewise to the filter element. [0022] For the rest, the technical object is solved according to the invention in that the fastening housing part includes a switching component that is suited to interact with a switching component of the filter element such that a switching device embodied with the switching components, upon an impulse-like relative axial movement of the filter element in a direction toward the fastening housing part, causes a rotation of the filter element relative to the fastening housing part around a rotation/insertion axis of the filter in order to move the detent means into the recess, depending on the position of the detent means in the recess prior to effecting the axial movement. The advantages mentioned above in connection with the filter and filter element according to the invention extend likewise to the filter element. [0023] Moreover, the technical object is solved according to the invention in that the telescopic switching element is adapted to be connected with the filter element or with the fastening housing part and the telescopic switching element includes at least one switching lug that extends radially relative to a rotation/insertion axis of the filter, the switching lug adapted to be guided in a switching guide that is connected appropriately with the fastening housing part or with the filter element in such a way that the switching guide guides the switching lug upon an impulse-like relative axial movement of the filter element in a direction toward the fastening housing part and thereby causes a rotation of the filter element relative to the fastening housing part around the rotation/insertion axis for actuation of the detent connection. The advantages mentioned above in connection with the filter, filter element and fastening housing part according to the invention extend likewise to the filter element. [0024] Advantageously, the telescopic switching element may comprise a releasable locking mechanism which is activated in the basic state and blocks the telescopic switching element from being pushed together, and which is matched to a release element that is connected to the fastening housing part or to the filter element such that the release element, upon installation of the filter element into the fastening housing part, deactivates the locking mechanism. BRIEF DESCRIPTION OF THE DRAWINGS [0025] The accompanying Figures, where like reference numerals refer to identical or functionally similar elements throughout the separate views and which together with the detailed description below are incorporated in and form part of the specification, serve to further illustrate various embodiments and to explain various principles and advantages all in accordance with the present invention. [0026] Features of the present invention, which are believed to be novel, are set forth in the drawings and more particularly in the appended claims. The invention, together with the further objects and advantages thereof, may be best understood with reference to the following description, taken in conjunction with the accompanying drawings. The drawings show a form of the invention that is presently preferred; however, the invention is not limited to the precise arrangement shown in the drawings. [0027] FIG. 1 schematically depicts a longitudinal section of an oil filter with an exchangeable filter element which is fastened with a releasable detent connection in a filter cup, wherein the detent connection is activatable and deactivatable with a switching device; [0028] FIG. 2 schematically depicts an exploded view of the detent connection and of the switching device of the oil filter of FIG. 1 wherein from bottom to top a side view of a dipping cylinder, a developed view of the geometry of a switching sleeve of the switching device, a developed view of the geometry of a detent guide, and a longitudinal section of a detent end disc of the filter element with three detent lugs are shown; [0029] FIG. 3 is an isometric detail view of the detent end disc of the filter element of FIG. 2 ; [0030] FIG. 4 is an isometric detail view of the filter element of FIGS. 1 to 3 , cut in half in longitudinal direction, in the area of a seal end disc with a moveable ring seal; [0031] FIG. 5 is an isometric representation of another aspect of a filter element according to the invention present in the filter element of FIG. 1 ; [0032] FIG. 6 is an isometric representation of the filter element of FIG. 5 , cut in half in longitudinal direction, in the area of a detent end disc; [0033] FIG. 7 schematically depicts a longitudinal section of an oil filter with the filter element according to the inventive aspects presented in FIGS. 5 and 6 in the area of the detent connection and the switching device; [0034] FIG. 8 schematically depicts an isometric representation of a dipping cylinder of the oil filter of FIG. 7 ; [0035] FIG. 9 schematically depicts an isometric representation of a another aspect of the invention with a filter element which is similar to the filter elements of FIGS. 1 to 7 ; [0036] FIG. 10 schematically depicts an isometric representation of further aspect of the invention having a filter element which is similar to the filter elements of FIGS. 1 to 7 and 9 ; [0037] FIG. 11 schematically depicts a longitudinal section of an oil filter that is similar to the oil filters of Figure and 1 and 7 with a moveable ring seal in the area of the screw connection of a housing cup with a housing cup; [0038] FIG. 12 schematically depicts the ring seal of FIG. 11 in cross-section; [0039] FIG. 13 schematically depicts a detail of an alternative detent guide which is similar to the detent guide of FIG. 2 ; [0040] FIG. 14 schematically depicts an isometric representation of the filter cup with the filter element of the oil filter of FIG. 1 in an assembly state before connecting with the filter head; [0041] FIG. 15 schematically depicts an isometric representation of the filter cup with the filter element of FIGS. 1 and 14 in a dismantled state for draining off the residual oil; [0042] FIG. 16 schematically depicts a longitudinal section of an oil filter with a filter element according to a fifth embodiment which is similar to the oil filter of FIGS. 7 and 8 in the area of a detent connection and a switching device in a first assembly state; [0043] FIG. 17 schematically depicts the oil filter of FIG. 16 in the final assembled state; [0044] FIG. 18 schematically depicts the oil filter of FIG. 16 in the first assembly state in a part-sectional view; [0045] FIG. 19 schematically depicts the oil filter of FIG. 17 in the final assembled state in a part-sectional view; [0046] FIG. 20 schematically depicts the oil filter of FIG. 18 in the first assembly state without illustration of the filter element; [0047] FIG. 21 schematically depicts the oil filter of FIG. 19 in the final assembled state without illustration of the filter element; [0048] FIG. 22 is a detail view of the switching device of the oil filter of FIG. 16 in the first assembly state; [0049] FIG. 23 is a detail view of the switching device of the oil filter of FIG. 17 in the final assembled state; [0050] FIG. 24 is a detail view of the filter element of the oil filter of FIG. 16 ; [0051] FIG. 25 depicts a stationary cylinder of a telescopic switching element of the switching device of the oil filter of FIG. 16 ; [0052] FIG. 26 depicts a dipping cylinder of the telescopic switching element of the switching device of the oil filter of FIG. 16 viewed in the direction of the inside; and [0053] FIG. 27 depicts the dipping cylinder of FIG. 27 with a view of the outside. [0054] In the Figures above, same components are provided with the same reference characters. [0055] Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention. DETAILED DESCRIPTION [0056] In FIG. 1 an oil filter 10 is shown for filtering engine oil of an internal combustion engine, not shown here, of a motor vehicle. [0057] The oil filter 10 has a filter housing 12 which is composed of a filter cup 14 and a filter head 16 . The filter head 16 is connected in a way of no further interest in this context to an engine oil system, not shown, of the internal combustion engine. The filter cup 14 is screwed from below into the filter head 16 and is suspended from it. [0058] An interchangeable filter element 18 is fastened by means of a releasable detent connection 20 in the filter cup 14 that functions as a fastening housing part. The filter element 18 includes a filter medium 22 which is folded coaxially relative to a rotation/insertion axis 30 of the filter housing 12 in a zigzag shape. A seal end disc 24 and a detent end disc 26 are fastened to the end faces of the filter medium 22 . In the interior of the filter medium 22 a support tube 28 that is fluid-permeable in radial direction extends between the seal end disc 24 and the detent end disc 26 coaxially to the rotation/insertion axis 30 . [0059] The rotation/insertion axis 30 is the axis relative to which during assembly or disassembly of the oil filter 10 the rotary and insertion movements of the filter head 16 , the filter cup 14 and the filter element 18 relatively to each other occur. The term rotation/insertion axis 30 is used in the following for better clarity also for the individual components of the oil filter 10 with open filter housing 12 and is referenced in the Figures accordingly. In these cases, this refers to the respective axis of the component in question which coincides for the mounted oil filter 10 with the rotation/insertion axis 30 of the filter housing 12 . The concepts “radial”, “axial” and “in circumferential direction” refer to the rotation/insertion axis 30 or the corresponding axis of the respective component. [0060] The detent connection 20 includes three detent lugs 32 as detent means which, as shown in particular in FIG. 3 , are arranged evenly distributed on the circumferential side of the detent end disc 26 of the filter element 18 that is facing the bottom 34 of the filter cup 14 . The detent lugs 32 extend in radial direction outwardly. The detent lugs 32 interact with a detent guide 36 of the detent connection 20 . [0061] The detent guide 36 is located near the bottom 34 on the radial inner circumferential side of the filter cup 14 . The detent guide 36 includes an elevated part 37 extending in radial direction with three recesses 38 that in each case correspond with one of the detent lugs 32 . In the recesses 38 the detent lugs 32 can lock in a bayonet-like manner. In FIG. 1 , the area of the detent guide 36 , which is hidden actually by the filter element 18 , is indicated in dashed lines to improve comprehension. The recesses 38 comprise, as shown in particular in FIG. 2 , in each case a locking area 40 , a retaining area 42 , a translation area 44 and an insertion/removal area 46 . [0062] The insertion/removal area 46 extends in axial direction. At its end that is facing the open side of the filter cup 14 the insertion/removal area 46 includes an opening 48 . The opening 48 is formed all together approximately in a funnel shape. The edges are rounded, so that insertion of the detent lugs 32 is simplified. At its closed end, the insertion/removal area 46 passes into the locking area 40 . [0063] The locking area 40 extends in circumferential direction on the rearward side of the insertion/removal area 46 relative to a rotational direction of locking of the filter cup 14 . The rotational direction of locking is indicated in FIG. 2 by arrow 50 . [0064] The retaining area 42 is located in axial direction between the opening 48 of the insertion/removal area 46 and the locking area 40 . It extends in circumferential direction at the front side of the insertion/removal area 46 relative to the rotational direction of locking 50 of the filter cup 14 . A retaining side 52 of the retaining area 42 facing the opening 48 extends in a plane perpendicular to the rotation/insertion axis 30 . An opposite guiding side 54 extends at an angle toward the retaining side 52 so that the retaining area 42 as a whole has an approximately triangular shape. Between the insertion/removal area 46 and the retaining area 42 a triangular projection 56 borders the guiding side 54 and tapers in axial direction away from the bottom 34 . The projection 56 forms a surmountable stop for the detent lug 32 . The projection 56 prevents that the filter element 18 is turned in the filter cup 14 unintentionally such that the detent lug 32 reaches the insertion/removal areas 46 causing the detent connection 20 to be released. [0065] The axial distance between the retaining side 52 of the retaining area 42 and a locked position retaining side 57 on the side of the locking area 40 that is facing the opening 48 determines how far the filter element 18 projects in a secured position described below from the filter head 14 . [0066] The translation area 44 forms the closed end of the insertion/removal area 46 . It extends at an angle to the rotation/insertion axis 30 of the filter cup 14 of the locked position retaining side 57 of the locking areas 40 to the projection 56 of the retaining area 42 . The contour of the translation area 44 passes into the contour of the projection 56 . [0067] A switching device 58 includes a telescopic switching element 60 at the filter head 14 which corresponds with a switching sleeve 62 on the filter element 18 . [0068] The telescopic switching element 60 includes a hollow stationary cylinder 64 which is open at an end face and is closed at the other end face. The stationary cylinder 64 is fastened with a screw 68 at the closed end face in a depression 66 of the bottom 34 of the filter cup 14 . [0069] In the stationary cylinder 64 a coaxial dipping cylinder 70 is moveable axially relative to the rotation/insertion axis 30 . The dipping cylinder 70 is also hollow and closed at one end face. The open end face of the dipping cylinder 70 is facing the closed end face of the stationary cylinder 64 . [0070] The dipping cylinder 70 includes at its open end face two spring hooks 72 which extend in axial direction and whose locking sides are directed in radial direction outwardly. The spring hooks 72 are guided in two suitable guide slots 74 in the circumferential side of the stationary cylinder 64 . The guide slots 74 extend axially relative to the rotation/insertion axis 30 . The guide slots 74 are closed relative to both end faces of the stationary cylinder 64 . The dipping cylinder 70 is secured against rotation by means of the spring hooks 72 and is axially slideable in the stationary cylinder 64 . [0071] The dipping cylinder 70 includes two switching lugs 76 which are arranged on the radial external circumferential side and extend in radial direction outwardly. The switching lugs 76 are arranged near the closed end face of the dipping cylinder 70 on sides that are diametrically opposed relative to the rotation/insertion axis 30 . [0072] The switching sleeve 62 is a cylindrical depression which extends in the center of the detent end disc 26 of the filter element 18 in axial direction toward the seal end disc 24 . The switching sleeve 62 includes at its radial inward side a switching guide 78 that projects in radial direction inwardly. The switching guide 78 includes a succession of progressing switching teeth 80 in circumferential direction. In FIG. 1 the area of the switching guide 78 , which is actually hidden in that representation by the dipping cylinder 70 , is shown in dash-dotted lines for better comprehension. Each progressing switching tooth 80 has, as shown in particular in FIG. 2 , a surface extending in axial direction and a guide surface 82 extending at an angle thereto. The guide surfaces 82 are arranged on the side of the switching guide 78 that is facing the opening of the switching sleeve 62 . The switching guide 78 serves for guiding the switching lugs 76 in case of an impulse-like relative axial movement of the filter element 18 into the filter cup 14 . [0073] Inside the telescopic switching element 60 a spiral compression spring 84 is arranged coaxially to the rotation/insertion axis 30 . The spiral compression spring 84 is supported with one end on an end wall of the stationary cylinder 64 and with the other end on an end wall of the dipping cylinder 70 . The spiral compression spring 84 of the telescopic switching element 60 serves for introducing a spring force that is acting axially to the rotation/insertion axis 30 for pressing the switching lugs 76 against the switching guide 78 . [0074] On the seal end disc 24 of the filter element 18 , as shown in the FIGS. 1 and 4 , a flexible ring seal 86 for sealing relative to the filter housing 12 is arranged. The ring seal 86 is fastened coaxially to the rotation/insertion axis 30 on a shape-stable support ring 88 which is slideable, in turn, axially relative to the filter element 18 . The ring seal 86 has a half moon-shaped profile whose curved side is positioned in radial direction outwardly. The straight axial inner side of the ring seal 86 rests flat against a radial outwardly positioned circumferential side of the support ring 88 . In the radial outwardly positioned circumferential side of the support ring 88 there is a circumferential groove 90 engaged by a suitable projection 92 that is provided for holding the ring seal 86 on the support ring 88 and is located on the radial inner side of the ring seal 86 . [0075] On an end face of the support ring 88 which is facing the filter element 18 a plurality of guide frames 94 are arranged in circumferential distribution. The guide frames 94 each have an elongate guide gap 96 which extends in axial direction. The guide frames 94 taper at their free ends in order to facilitate assembly. [0076] On the radial outer circumferential side of the seal end disc 24 there are guide projections 98 which correspond with the guide gaps 96 . The guide projections 98 extend radially in outward direction. The guide frames 94 are guided on the guide projections 98 . [0077] The expansion of the guide projections 98 in circumferential direction corresponds approximately to the expansion of the guide gaps 96 in circumferential direction so that a relative movement between the support ring 88 and the seal end disc 24 relative to the rotation/insertion axis 30 is prevented. [0078] The expansion of the guide gap 96 in axial direction is significantly bigger than the expansion of the guide projections 98 in axial direction so that a relative movement of the support ring 88 with the ring seal 86 is possible in axial direction relative to the filter element 18 . [0079] For assembly of the oil filter 10 , the filter element 18 with the detent end disc 26 leading is inserted axially relative to the rotation/insertion axis 30 into the filter cup 14 . In this context, it may possibly be necessary to turn the filter element 18 in the filter cup 14 somewhat around the rotation/insertion axis 30 so that the three detent lugs 32 are able to glide unhindered in each case into one of the insertion/removal areas 46 of the detent guide 36 . This is facilitated by the funnel-shaped openings 48 with the rounded edges. Upon insertion of the filter element 18 , the dipping cylinder 70 dips into the switching sleeve 62 . The spiral compression spring 84 ensures that the filter element 18 is not immersed completely into the filter cup 14 . The filter element 18 projects from the filter cup 14 in this phase of assembly. The support ring 88 with the ring seal 86 is outside of the filter cup 14 . [0080] By means of the geometrically matched pairs of the detent lugs 32 with the recesses 38 of the detent guide 14 and the pairing of the switching lugs 76 of the dipping cylinder 70 with the switching guide 78 of the switching sleeve 62 , it is prevented that the filter element 18 can be mounted wrongly or that a non-matching filter element can be used. In this manner, the risk that malfunctions of the oil filter 10 occur is reduced. [0081] The filter element 18 is pressed for activation of the detent connection 20 with an impulse-like movement in axial direction into the filter cup 14 in. In this context, the movement direction of the switching guide 78 is indicated in FIG. 2 with arrow 99 . This axial movement can be generated by pressing with one hand or by pressing the filter cup 14 with the free end face of the filter element 18 against a tabletop or another stable object. With the axial movement the switching lugs 76 of the dipping cylinder 70 are guided along the guide surfaces 82 of the switching guide 78 so that a rotation of the filter element 18 is caused relatively to the filter cup 14 around the rotation/insertion axis 30 . In this context, the rotation direction of the filter element 18 is indicated in FIG. 2 by arrows 100 . The detent lugs 32 are moved from the insertion/removal areas 46 of the respective recess 38 into the locking areas 40 by the rotation of the filter element 18 . [0082] The locking areas 40 serve for receiving the detent lugs 32 when screw-connecting the filter cup 14 with the filter head 16 . In this dismantling phase the filter element 18 presses against the spiral compression spring 84 so that the latter is pre-tensioned. The ring seal 86 is resting on the edge of the filter cup 14 . For better clarity, in FIG. 14 the illustration of the ring seal 86 has been omitted. The filter element 18 is secured by the detent connection 20 in the filter cup 14 so that the latter, for joining with the filter head 16 , can be turned or tilted in all spatial directions without the filter element 18 falling out. In this manner, an assembly, hidden from view, f the filter cup 14 in the filter head 16 is easily possible. [0083] The filter cup 14 with the filter element 18 is screwed from below into the filter head 16 . In this context, the detent lugs 32 are still secured in the locking areas 40 . The ring seal 86 is resting in the installation position shown in FIG. 1 tightly against suitable sealing surfaces at the inner wall of the filter head 16 and separates the clean side of the filter element 18 from the raw side. [0084] For dismantling, the filter cup 14 is unscrewed in opposite direction of rotation from the filter head 16 . In this context, by friction between the filter element 18 , in particular the ring seal 86 , and the filter head 16 it is effected that the filter element 18 is somewhat turned in the filter cup 14 . When doing so, the detent lugs 32 move out of the locking areas 40 into the respective translation areas 44 . Upon further unscrewing, the detent lugs 32 are guided along the translation areas 44 into the retaining areas 42 . By relative movement of the filter element 18 in axial direction out of the filter cup 14 , a volume is released at the bottom 34 of the filter cup 14 in which the residual oil is caught that is still contained in the filter housing 12 . In this manner, it is prevented that oil reaches the surroundings when exchanging the filter element 18 from the oil filter 10 . [0085] During the further opening phase of the filter housing 12 , the detent lugs 32 are retained in the retaining areas 42 . In this retaining position, the filter element 18 projects by about 1 cm out of the filter cup 14 . [0086] Moreover, the ring seal 86 is moved during the opening phase axially with respect to the rotation/insertion axis 30 relative to the filter element 18 . While unscrewing, the ring seal 86 remains in the filter head 16 until the guide projections 98 of the seal end disc 24 hit the boundaries of the guide gaps 96 at the free ends of the guide frames 94 of the support ring 88 . Thus, it is prevented that the oil escapes to the surroundings. [0087] The filter head 16 completely separated from filter cup 14 is turned upside down, so that its open side points downwardly. When doing so, the filter element 18 is retained with the detent connection 20 in the filter cup 14 so that it cannot uncontrollably fall from the filter cup 14 . This dismantling state is shown in FIG. 15 . The representation of the ring seal 86 was omitted for better clarity. The filter cup 14 can be placed with the open side facing down for draining the oil, for example, into a drain pan or a different type of support. [0088] The filter element 18 is pressed with an impulse-like movement in axial direction into the filter cup 14 . This can be done, for example, by pressing with one hand onto the bottom 34 of the filter cup 14 wherein the free end face of the filter element 18 is pressed against the drain pan. In this connection, the switching lugs 76 of the dipping cylinder 70 are guided along the guide surfaces 82 of the switching guide 78 so that a rotation of the filter element 18 relative to the filter cup 14 is effected around the rotation/insertion axis 30 . [0089] With this rotation of the filter element 18 , the detent lugs 32 are moved from the retaining areas 42 into the insertion/removal areas 46 for deactivation of the detent connection 20 . In the insertion/removal areas 46 , the detent lugs 32 and the recesses 38 can be separated from each other unhindered. [0090] After deactivation of the detent connection 20 , the spiral compression spring 84 can relax and, in this way, causes the filter element 18 to be pushed in axial direction out of the filter cup 14 . When lifting the filter cup 14 , the filter element 18 remains in the drain pan. [0091] All together, the filter cup 14 with the filter element 18 can be mounted in a simple way with one hand even at hard-to-access and/or hidden sites, for example, in an engine compartment. A used filter element 18 can be exchanged simply with one hand and the oil-smeared filter element 18 itself must not be touched. [0092] In a second embodiment, shown in FIGS. 5 to 8 , those elements which are similar to those of the first embodiment described in FIGS. 1 to 4 are provided with the same reference characters so that with regard to their description reference is being had to the explanations relating to the first embodiment. This embodiment differs from the first one by the fact that the detent lugs 32 are arranged at the free ends of two detent wings 132 that are diametrically opposed relative to the rotation/insertion axis 30 . The detent wings 132 are arranged on a detent ring 133 which is fastened coaxially to the rotation/insertion axis 30 on the exterior side of the detent end disc 26 that is facing away from the filter medium 22 . The detent wings 132 extend basically in radial direction outwardly. The free ends of the detent wings 132 are bent in the same circumferential direction and form the detent lugs 32 . The detent guide 36 is configured similar to the detent guide 36 of the first embodiment. [0093] In the second embodiment, the switching guide 78 has switching angled members 182 instead of the progressing switching teeth 80 of the first embodiment. [0094] A moveable ring seal 186 , as shown in FIG. 5 , is arranged in the second embodiment in axial direction between the seal end disc 24 and the detent end disc 26 . The ring seal 186 seals in the installed position, not shown in FIG. 5 , in the area of the seal end disc 24 . [0095] In FIG. 7 , a detail of the detent guide 36 is shown which includes alternative recesses 38 which are similar to the recesses 38 according to the first embodiment. [0096] The stationary cylinder 164 of the modular telescopic switching element 60 includes a central support sleeve 165 for centering the spiral compression spring 84 . The spiral compression spring 84 is embedded at one end in the end wall of the dipping cylinder 170 . The telescopic switching element 60 is shown in FIG. 8 in isometric representation. [0097] In a filter element 18 according to a third embodiment, shown in FIG. 9 , those elements which are similar to those of the first embodiment described in FIGS. 1 to 4 are provided with the same reference characters so that with regard to their description reference is being had to the explanations provided for the first embodiment. This embodiment differs from first one in that, similar to the second embodiment, three detent wings 132 with the detent lugs 32 are provided in a distributed arrangement in circumferential direction and extend basically in radial direction outwardly. They are arranged in analogy to the second embodiment on a detent ring 133 . [0098] In addition, the third embodiment includes an alternative switching device 58 which is connected with a drain valve 135 that is of no further interest here. [0099] In a filter element 18 according to a fourth embodiment, shown in FIG. 10 , four detent lugs 32 are provided instead of three detent lugs 32 of the first embodiment. This affects positively the force distribution when retaining the filter element 18 in the filter cup 14 . Further, the guide projections 98 for guiding the support ring, not shown in FIG. 10 , for the slideable ring seal are arranged on a guide ring 200 that is coaxial to the rotation/insertion axis 30 . The guide ring 200 is fastened to the outside of the seal end disc 24 that is facing away from the filter medium 22 . [0100] In FIG. 11 , a detail view of an axially slideable ring seal 86 with half moon-shaped profile is shown according to a fifth embodiment. The ring seal 86 is arranged, as in the first embodiment of FIGS. 1 to 4 , on a support ring 88 . In contrast to the first embodiment, the guide projections 98 for guiding the guide frames 94 of the support ring 88 are however on the radial inner side of a cylindrical wall 202 of the seal end disc 24 of the filter element 18 . In addition, the seal end disc 24 includes a radial outwardly extending projection 204 which when the filter housing 12 is mounted is resting against an end face edge of the filter cup 14 . Between the opposed end face of the projection 204 and an appropriate end face edge of the filter head 16 , the ring seal 86 is arranged. In FIG. 12 , the ring seal 86 of FIG. 1 is shown in the relaxed state (I) and in the compressed state (II), as it exists when the filter housing 12 is mounted. [0101] In FIG. 13 , an alternative recess 38 of a switching guide 78 is shown which is similar to the switching guide 78 of the first embodiment according to FIGS. 1 and 4 . Here, a detent hook 232 is illustrated in dashed lines and includes the detent lug 32 at its free end. In contrast to the first embodiment, the retaining area 42 and the locking area 40 in each case have an axially extending projection 234 at their end that is facing the insertion/removal area 46 at the side that is facing the opening 48 . The projections 234 prevent the detent lugs 32 from unintentional rotation into the insertion/removal area 46 and thus from unintentional deactivation of the detent connection 20 . [0102] In a fifth embodiment, shown in FIGS. 16 to 27 , reference is being had to the explanations provided for the first or second embodiment with respect to those elements which are similar to those of the first embodiment described in FIGS. 1 to 4 and to those of the second embodiment described in FIGS. 5 to 8 . FIGS. 16 , 18 , 20 and 22 show a first assembly state during installation of the filter element 518 into the filter cup 514 . FIGS. 17 , 19 , 21 and 23 show a final assembled state of the filter element 518 in the filter cup 514 . The representation of the filter medium on the support tube 28 was omitted in FIGS. 16 to 27 for better clarity. In FIGS. 20 and 21 the representation of the filter element 518 was omitted in favor of clear illustration of the telescopic switching element 560 . [0103] The fifth embodiment differs from the first and the second embodiment in that the switching device 558 includes a locking mechanism 559 which is activated in the basic state of the telescopic switching element 560 and blocks pushing together the telescopic switching element 560 . [0104] The dipping cylinder 570 of the telescopic switching element 560 , as shown in particular in FIG. 27 , is shaped conically at its closed end face that is facing away from the stationary cylinder 564 . For better clarity, the spiral compression spring 584 which forces the dipping cylinder 570 away from the stationary cylinder 564 in the basic state of the telescopic switching element 560 is indicated only in FIG. 17 . [0105] Three radial springy locking spring hooks 571 of the locking mechanism 559 are arranged in symmetric distribution relative to the rotation/insertion axis 530 in axial recesses in the circumferential wall of the dipping cylinder 570 . They extend in axial direction. Their free ends are located at the closed end face of the dipping cylinder 570 and project past the latter in axial direction. The free ends of the locking spring hooks 571 are formed to detent projections 573 which projects in radial direction outwardly. In the area of the detent projections 573 , the locking spring hooks 571 are bent radially in inward direction. [0106] The detent projections 573 project past the conical area of the dipping cylinder 570 in radial direction. On their sides facing away from the free ends of the locking spring hooks 571 , the detent projections 573 have locking steps 575 . The locking steps 575 project past the cylindrical segment of the circumferential wall of the dipping cylinder 570 in radial direction. [0107] The end wall at the closed end face of the dipping cylinder 570 includes circumferentially three indentations 577 which pass into recesses in which the locking spring hooks 571 are located. The locking spring hooks 571 can engage the indentations 577 by spring action in radial direction so that the radial outer sides of the detent projections 573 are positioned in radial direction at the level of the radial outer side of the cylindrical segment of the circumferential wall of the dipping cylinder 570 or even radially inside thereof. [0108] Between two of the locking spring hooks 571 , respectively, there is arranged one of a total of three spring hooks 572 on the radial outer side of the cylindrical segment of the circumferential wall of the dipping cylinder 570 . The spring hooks 572 are guided in three suitable guide slots 574 in the circumferential wall of the stationary cylinder 564 ; this is shown in particular in FIG. 25 . The guide slots 574 extend axially relative to the rotation/insertion axis 530 . [0109] The stationary cylinder 564 includes in its circumferential wall between two of the guide slits 574 , respectively, one of a total of three locking guide slots 579 in which the detent projections 573 of the locking spring hooks 571 of the dipping cylinder 570 are guided. The locking guidance slots 579 extend axially relative to the rotation/insertion axis 530 . [0110] The edge at the open end face of the stationary cylinder 564 is beveled on the radial inner side, exclusive of those areas in which the locking guide slots 579 adjoin. In this manner, the spring hooks 572 are able to glide more easily into the guide slots 574 when assembling the telescopic switching element 560 . In the area of the locking guide slots 579 the edge of the stationary cylinder 564 is formed to locking stops 581 for the locking steps 575 of the locking spring hooks 571 . [0111] Between one of the guide slots 574 and one the locking guide slots 579 , respectively, a switching lug 576 is arranged on the radial outer side of the circumferential wall of the stationary cylinder 564 and extends in radial direction outwardly. The switching lugs 576 are approximately of parallelepipedal shape wherein two corners is slanted that, upon installation of the filter element 518 , are resting on a guide surface 582 of the switching guide 578 of the switching sleeve 562 , shown in FIGS. 18 and 19 in particular. [0112] On the filter element 518 a release sleeve 583 , as shown in particular in FIG. 24 , is arranged coaxially within switching sleeve 562 . The release sleeve 583 is adapted, for deactivation of the locking mechanism 559 , to the geometry of the locking spring hooks 571 of the dipping cylinder 570 . On the edge of the open end face of the release sleeve 583 the radius of its radial inner circumferential side is greater than the distance between the radial outer side of the detent projections 573 at the free end of the locking spring hooks 571 and the rotation/insertion axis 530 . In this manner, when inserting the telescopic switching element 560 into the switching sleeve 562 , the release sleeve 583 can press in radial direction from the outside against the detent projections 573 and bend the locking spring hooks 571 in radial direction inwardly. In this connection, the locking steps 575 are pushed away by the locking stops 581 of the stationary cylinder 564 in radial direction inwardly so that the locking mechanism 559 is deactivated and the telescopic switching element 560 can be pushed together. [0113] When it is attempted to install a filter element into the filter cup 514 without the release sleeve 583 that is matching the telescopic switching element 560 , the locking mechanism 559 remains activated and the telescopic switching element 560 cannot be pushed together. The extended telescopic switching element 560 prevents the installation of the filter element that does not fit, which is recognizable clearly from the outside. In this manner, limitations and/or disturbances of the filter function of the oil filter 510 which can be caused by using a filter element that does not fit are prevented. [0114] The release sleeve 583 includes at its free end face three indentations 585 which interrupt the edge of the release sleeve 583 in circumferential direction at uniform spacings. The indentations 585 extend in axial direction. The sides of the indentations 585 that are positioned to the rear when viewed in axial direction from the edge of the release sleeve 583 pass in each case into a slant located at the radial inner circumferential side of the release sleeve 583 . The indentations 585 are so arranged in circumferential direction with regard to the guide surfaces 582 of the switching guide 578 of the switching sleeve 562 that the engaged locking spring hooks 571 , in the final assembled state as shown in FIG. 23 , are immersed in the indentations 585 and thereby can relax. In this manner, the mechanical load of the locking spring hooks 571 is reduced and their life span is increased. [0115] The switching guide 578 with the progressing switching teeth 580 is realized in the form of penetrations in the switching sleeve 562 . [0116] Within the release sleeve 583 there is a coaxial stop cylinder 587 and, in axial direction, the release sleeve 583 projects past it. Upon inserting the telescopic switching element 560 into the switching sleeve 562 , the dipping cylinder 570 with his closed end face hits the stop cylinder 587 and presses thus the dipping cylinder 570 in the stationary cylinder 564 . [0117] The activation and deactivation of the detent connection 20 , which includes the detent wings 32 and the detent guide 36 , by means of the switching device 558 functions in analogy to the above explained embodiments. [0118] In all of the above described embodiments of an oil filter 10 , a filter element 18 ; 518 , and a filter cup 14 ; 514 , the following modifications are possible inter alia: [0119] The invention is not limited to oil filters 10 of internal combustion engines in motor vehicles. Rather, it can be also used in different filters, for example, fuel filters or air filters, of internal combustion engines, industrial engines or compressors. A filter according to the invention can also be used in other technical fields of application. [0120] The filter medium 22 can be folded or formed differently than in a zigzag shape. [0121] The filter housing 12 can also be comprised of more than two housing parts. [0122] The filter cup 14 ; 514 can be mounted, instead of being suspended, also at an angle or standing upright from above on the filter head 16 . Instead of the filter head 16 a different housing part can be provided for attachment of the filter element 18 ; 518 . Instead of being screwed into or onto the filter head 16 , the filter cup 14 ; 514 can be connected also by means of another rotation and/or insertion connection, for example, a bayonet connection, in a releasable way with the filter head. [0123] Instead of the detent lugs 32 , different detent means can be also provided. Suitable detent means can be connected, instead of with the filter element 18 ; 518 , also with the filter cup 14 ; 514 ; the detent guide is then appropriately arranged at the filter element 18 ; 518 . [0124] The telescopic switching element 60 ; 560 or a suitable different switching device can be connected, instead of with the filter cup 14 ; 514 , also with the filter element 18 ; 118 . Accordingly, the switching guide 78 is then arranged at the filter cup 14 ; 514 . [0125] The switching device 58 ; 518 also can have more or fewer than two or three switching lugs 76 ; 576 . [0126] The switching device can also be arranged on a circumferential side of the filter element and the detent device can be arranged, instead, at the center of the detent end disc of the filter element. [0127] Instead of the spiral compression spring 84 ; 584 , a different elastic element, for example, a leaf spring or an elastic plastic element, can be provided also which is adapted to realize a restoring force. [0128] The filter element 18 ; 118 can project in the dismantling phase, in which the detent lugs 32 ; 532 are retained in the retaining areas 42 , also more or less than 1 cm past the filter cup 14 ; 514 . [0129] The retaining side 52 of the retaining area 42 and the locked position retaining side 57 of the locking area 40 can also extend within a plane that is perpendicular to the rotation/insertion axis 30 ; 530 . [0130] When the sides that are positioned respectively opposite the locked position retaining side 57 of the locking area 40 and the retaining side 52 of the retaining area 42 extend in a common plane perpendicular to the rotation/insertion axis 30 ; 35 , the translation area 44 can also extend within this plane. [0131] The detent connection and the switching device can also be combined. In particular, the detent connection can be designed in such a way, that the functions of the switching device realized and vice versa. [0132] The locking mechanism 559 for the telescopic switching element 560 and/or the release element 583 can be also designed to match each other in a different way. [0133] In the foregoing specification, specific embodiments of the present invention have been described. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present invention. The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential features or elements of any or all the claims The invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued.

A filter ( 18 ) is fastened by means of a releasable detent connection ( 20 ) in a fastening housing part ( 14 ). One detent component ( 32 ) is connected to the filter element ( 18 ) and one detent component ( 36 ) is connected to the fastening housing part ( 14 ). At least one detent means ( 32 ) of one of the detent components engages in a bayonet-like manner in a cut-out ( 38 ) in the other detent component ( 36 ). One switching component ( 60 ) of a switching device ( 58 ) is connected to the filter element ( 18 ) and one switching component ( 62 ) is connected to the fastening housing part ( 14 ). One of the switching components ( 60 ) includes at least one switching lug ( 76 ) extending radially to a rotational/plug-in axis ( 30 ) of the filter ( 10 ), and one of the switching components ( 62 ) includes a switching slot ( 78 ) for guiding the switching lug ( 76 ). The switching slot ( 78 ) guides the switching lug ( 76 ) and thereby effects a rotational movement of the filter element ( 18 ) relative to the fastening housing part ( 14 to move the detent means ( 32 ) out of an insertion/withdrawal region ( 46 ) into a closing region ( 40 ) of the cut-out ( 38 ), or out of a retaining region ( 42 ) into the insertion/withdrawal region ( 46 ).

This application claims the benefit of provisional U.S. patent application Ser. No. 60/013,432, filed Mar. 14, 1996. BACKGROUND OF THE INVENTION Compounds of formula ##STR2## wherein R 1 is hydrogen or a lower alkyl radical and n is 4, 5, or 6 are known in U.S. Pat. No. 4,024,175 and its divisional U.S. Pat. No. 4,087,544. The uses disclosed are: protective effect against cramp induced by thiosemicarbazide; protective action against cardiazole cramp; the cerebral diseases, epilepsy, faintness attacks, hypokinesia, and cranial traumas; and improvement in cerebral functions. The compounds are useful in geriatric patients. The patents are hereby incorporated by reference. SUMMARY OF THE INVENTION The novel substituted cyclic amino acids, their derivatives, prodrugs, and pharmaceutically acceptable salts are useful in a variety of disorders. The disorders include: epilepsy, faintness attacks, hypokinesia, cranial disorders, neurodegenerative disorders, depression, anxiety, panic, pain, and neuropathological disorders. The compounds are those of formula ##STR3## a pharmaceutically acceptable salt thereof or a prodrug thereof wherein R 1 to R 10 are each independently selected from straight or branched alkyl of from 1 to 6 carbon atoms, unsubstituted or substituted benzyl or phenyl which substituents are selected from halogen, alkoxy, alkyl, hydroxy, carboxy, carboalkoxy, trifluoromethyl, and nitro, and any R 1 to R 10 , which is not one of the above, is hydrogen. Especially preferred compounds of the invention are: (1-aminomethyl-4-tert-butyl-cyclohexyl)-acetic acid; (1-aminomethyl-3-methyl-cyclohexyl)-acetic acid; (1-aminomethyl-3-methyl-cyclohexyl)-acetic acid [1R-(1α,3β)]; (1-aminomethyl-3-methyl-cyclohexyl)-acetic acid [1S-(1α,3β)]; cis (1-aminomethyl-4-methyl-cyclohexyl)-acetic acid; cis (1-aminomethyl-4-isopropyl-cyclohexyl)-acetic acid; (1-aminomethyl-2-methyl-cyclohexyl)-acetic acid; (±)-(1-aminomethyl-3,3-dimethyl-cyclohexyl)-acetic acid; (1-aminomethyl-3,3,5,5-tetramethyl-cyclohexyl)-acetic acid; (1-aminomethyl-4-methyl-cyclohexyl)-acetic acid; (1-aminomethyl-3-methyl-cyclohexyl)-acetic acid methyl ester monohydrochloride; [1-(acetylamino-methyl)-3-methyl-cyclohexyl]-acetic acid; and [2-(1-Aminomethyl-3-methyl-cyclohexyl)-acetylamino]-acetic acid monohydrochloride. Novel intermediates useful in the preparation of the final products are disclosed as well as a novel process for the preparation of the compounds. DETAILED DESCRIPTION The compounds of the instant invention and their pharmaceutically acceptable salts are as defined by Formula I. The term "alkyl" is a straight or branched group of from 1 to 6 carbon atoms including but not limited to methyl, ethyl, propyl, n-propyl, isopropyl, butyl, 2-butyl, tert-butyl, pentyl, hexyl, and n-hexyl. Preferred groups are methyl and tert-butyl. The benzyl and phenyl groups may be unsubstituted or substituted by from 1 to 3 substituents selected from halogen, alkyl, alkoxy, hydroxy, carboxy, carboalkoxy, trifluoromethyl, and nitro. Halogen includes fluorine, bromine, chlorine, and iodine. Since amino acids are amphoteric, pharmacologically compatible salts when R is hydrogen can be salts of appropriate inorganic or organic acids, for example, hydrochloric, sulphuric, phosphoric, acetic, oxalic, lactic, citric, malic, salicylic, malonic, maleic, succinic, and ascorbic. Starting from corresponding hydroxides or carbonates, salts with alkali metals or alkaline earit metals, for example, sodium, potassium, magnesium, or calcium are formed. Salts with quaternary ammonium ions can also be prepared with, for example, the tetramethyl-ammonium ion. The carboxyl group of the amino acids can be esterified by known means. Certain of the compounds of the present invention can exist in unsolvated forms as well as solvated forms, including hydrated forms. In general, the solvated forms, including hydrated forms, are equivalent to unsolvated forms and are intended to be encompassed within the scope of the present invention. Certain of the compounds of the present invention possess one or more chiral centers and each center may exist in the R(D) or S(L) configuration. The present invention includes all enantiomeric and epimeric forms as well as the appropriate mixtures thereof. For example, the compound of Example 1 is a mixture of all four possible stereoisomers. The compound of Example 6 is one of the isomers. The configuration of the cyclohexane ring carbon centers may be R or S in these compounds where a configuration can be defined. The compounds of the invention may be synthesized, for example, by utilizing the general strategy (Scheme 1 below) outlined by Griffiths G., et al., Helv. Chim. Acta, 74:309 (1991). Alternatively, they may also be made as shown (in Scheme 2 below), analogously to the published procedure for the synthesis of 3-oxo-2,8-diazaspiro[4,5]decane-8-carboxylic acid tert-butyl ester (1) (Smith P. W., et al., J. Med. Chem., 38:3772 (1995)). The compounds may also be synthesized by the methods outlined by Satzinger G., et al., (U.S. Pat. No. 4,024,175 and U.S. Pat. No. 4,152,326) (Schemes 3 and 4 below). The compounds may also be synthesized by the route outlined by Griffiths G., et al., Helv. Chim. Acta. 74:309 (1991) as in Scheme 5 below. ##STR4## Examples of prodrugs are: ##STR5## These can be synthesized, for example, via the routes outlined in Schemes 6 through 8 below. ##STR6## The radioligand binding assay using [ 3 H]gabapentin and the α 2 δ subunit derived from porcine brain tissue was used ("The Novel Anti-convulsant Drug, Gabapentin, Binds to the α 2 δ Subunit of a Calcium Channel", Gee N., et al., J. Diological Chemistry, in press). TABLE 1______________________________________Compound Structure IC.sub.50 (μM)______________________________________ (1-aminomethyl-4-tert- butyl-cyclohexyl)-acetic acid 200 7## - (1-aminomethyl-3-methyl- cyclohexyl)-acetic acid 0.13 ## - (1-aminomethyl-3-methyl- cyclohexyl)-acetic acid [1R-(1α,3.be ta.)] 13 R9## - (1-aminomethyl-3-methyl- cyclohexyl)-acetic acid [1S-(1α,3.be ta.)] .030 0## - cis(1-aminomethyl-4- methyl-cyclohexyl)- acetic acid 10 R11## - cis(1-aminomethyl-4- isopropyl-cyclohexyl)- acetic acid 10 R12## - (1-aminomethyl-2-methyl- cyclohexyl)-acetic acid 7 TR13## - (±)-(1-aminomethyl- 3,3-dimethyl- cyclohexyl)-acetic acid 0.5 14## - (1-aminomethyl- 3,3,5,5-tetramethyl- cyclohexyl)-acetic acid 10 R15## - (1-aminomethyl-4-methyl- cyclohexyl)-acetic acid 0.3316##______________________________________ Table 1 above shows the binding affinity of the compounds of the invention to the α 2 δ subunit. Gabapentin (Neurontin®) is about 0.10 to 0.12 μM in this assay. The compounds of the instant invention are expected, therefore, to exhibit pharmacologic properties comparable to gabapentin. For example, as agents for convulsions, anxiety, and pain. The compounds of the invention are related to Neurontin®, a marketed drug effective in the treatment of epilepsy. Neurontin® is 1-(aminomethyl)-cyclohexaneacetic acid of structural formula ##STR17## The compounds of the invention are also expected to be useful in the treatment of epilepsy. See Table 1 above for IC 50 data as compared to Neurontin®. The present invention also relates to therapeutic use of the compounds of the mimetic as agents for neurodegenerative disorders. Such neurodegenerative disorders are, for example, Alzheimer's disease, Huntington's disease, Parkinson's disease, and Amyotrophic Lateral Sclerosis. The present invention also covers treating neurodegenerative disorders termed acute brain injury. These include but are not limited to: stroke, head trauma, and asphyxia. Stroke refers to a cerebral vascular disease and may also be referred to as a cerebral vascular incident (CVA) and includes acute thromboembolic stroke. Stroke includes both focal and global ischemia. Also, included are transient cerebral ischemic attacks and other cerebral vascular problems accompanied by cerebral ischemia. A patient undergoing carotid endarterectomy specifically or other cerebrovascular or vascular surgical procedures in general, or diagnostic vascular procedures including cerebral angiography and the like. Other incidents are head trauma, spinal cord trauma, or injury from general anoxia, hypoxia, hypoglycemia, hypotension as well as similar injuries seen during procedures from embole, hyperfusion, and hypoxia. The instant invention would be useful in a range of incidents, for example, during cardiac bypass surgery, in incidents of intracranial hemorrhage, in perinatal asphyxia, in cardiac arrest, and status epilepticus. A skilled physician will be able to determine the appropriate situation in which subjects are susceptible to or at risk of, for example, stroke as well as suffering from stroke for administration by methods of the present invention. The compounds of the invention are also expected to be useful in the treatment of depression. Depression can be the result of organic disease, secondary to stress associated with personal loss, or idiopathic in origin. There is a strong tendency for familial occurrence of some forms of depression suggesting a mechanistic cause for at least some forms of depression. The diagnosis of depression is made primarily by quantification of alterations in patients' mood. These evaluations of mood are generally performed by a physician or quantified by a neuropsychologist using validated rating scales, such as the Hamilton Depression Rating Scale or the Brief Psychiatric Rating Scale. Numerous other scales have been developed to quantify and measure the degree of mood alterations in patients with depression, such as insomnia, difficulty with concentration, lack of energy, feelings of worthlessness, and guilt. The standards for diagnosis of depression as well as all psychiatric diagnoses are collected in the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) referred to as the DSM-IV-R manual published by the American Psychiatric Association, 1994. GABA is an inhibitory neurotransmitter with the central nervous system. Within the general context of inhibition, it seems likely that GABA-mimetics might decrease or inhibit cerebral function and might therefore slow function and decrease mood leading to depression. The compounds of the instant invention may produce an anticonvulsant effect through the increase of newly created GABA at the synaptic junction. If gabapentin does indeed increase GABA levels or the effectiveness of GABA at the synaptic junction, then it could be classified as a GABA-mimetic and might decrease or inhibit cerebral function and might, therefore, slow function and decrease mood leading to depression. The fact that a GABA agonist or GABA-mimetic might work just the opposite way by increasing mood and thus, be an antidepressant, is a new concept, different from the prevailing opinion of GABA activity heretofore. The compounds of the instant invention are also expected to be useful in the treatment of anxiety and of panic as demonstrated by means of standard pharmacological procedures. MATERIAL AND METHODS carrageenin-Induced Hyperalgesia Nociceptive pressure thresholds were measured in the rat paw pressure test using an analgesymeter (Randall-Selitto method: Randall L. O. and Sellitto J. J., A method for measurement of analgesic activity on inflamed tissue. Arch. Int. Pharmacodyn., 4:409-419 (1957)). Male Sprague Dawley rats (70-90 g) were trained on this apparatus before the test day. Pressure was gradually applied to the hind paw of each rat and nociceptive thresholds were determined as the pressure (g) required to elicit paw withdrawal. A cutoff point of 250 g was used to prevent any tissue damage to the paw. On the test day, two to three baseline measurements were taken before animals were administered 100 μL of 2% carrageenin by intraplantar injection into the right hind paw. Nociceptive thresholds were taken again 3 hours after carrageenin to establish that animals were exhibiting hyperalgesia. Animals were dosed with either gabapentin (3-300 mg, s.c.), morphine (3 mg/kg, s.c.) or saline at 3.5 hours after carageenin and nociceptive thresholds were examined at 4, 4.5, and 5 hours postcarrageenin. Semicarbazide-Induced Tonic Seizures Tonic seizures in mice are induced by subcutaneous administration of semicarbazide (750 mg/kg). The latency to the tonic extension of forepaws is noted. Any mice not convulsing within 2 hours after semicarbazide are considered protected and given a maximum latency score of 120 minutes. Animals Male Hooded Lister rats (200-250 g) are obtained from Interfauna (Huntingdon, UK) and male TO mice (20-25 g) are obtained from Bantin and Kingman (Hull, UK). Both rodent species are housed in groups of six. Ten Common Marmosets (Callithrix Jacchus) weighing between 280 and 360 g, bred at Manchester University Medical School (Manchester, UK) are housed in pairs. All animals are housed under a 12-hour light/dark cycle (lights on at 07.00 hour) and with food and water ad libitum. Drug Administration Drugs are administered either intraperitoneally (IP) or subcutaneously (SC) 40 minutes before the test in a volume of 1 mL/kg for rats and marmosets and 10 mL/kg for mice. Mouse Light/Dark Box The apparatus is an open-topped box, 45 cm long, 27 cm wide, and 27 cm high, divided into a small (2/5) and a large (3/5) area by a partition that extended 20 cm above the walls (Costall B., et al., Exploration of mice in a black and white box: validation as a model of anxiety. Pharmacol. Biochem. Behav., 32:777-785 (1989)). There is a 7.5×7.5 cm opening in the center of the partition at floor level. The small compartment is painted black and the large compartment white. The white compartment is illuminated by a 60-W tungsten bulb. The laboratory is illuminated by red light. Each mouse is tested by placing it in the center of the white area and allowing it to explore the novel environment for 5 minutes. The time spent in the illuminated side is measured (Kilfoil T., et al., Effects of anxiolytic and anxiogenic drugs on exploratory activity in a simple model of anxiety in mice. Neuropharmacol., 28:901-905 (1989)). Rat Elevated X-Maze A standard elevated X-maze (Handley S. L., et al., Effects of alpha-adrenoceptor agonists and antagonists in a maze-exploration model of `fear`-motivated behavior. Naunyn-Schiedeberg's Arch. Pharmacol., 327:1-5 (1984)), was automated as previously described (Field, et al., Automation of the rat elevated X-maze test of anxiety. Br. J. Pharmacol., 102(Suppl):304P (1991)). The animals are placed on the center of the X-maze facing one of the open arms. For determining anxiolytic effects the entries and time spent on the end half sections of the open arms is measured during the 5-minute test period (Costall, et al., Use of the elevated plus maze to assess anxiolytic potential in the rat. Br. J. Pharmacol., 96(Suppl):312p (1989)). Marmoset Human Threat Test The total number of body postures exhibited by the animal towards the threat stimulus (a human standing approximately 0.5 m away from the marmoset cage and staring into the eyes of the marmoset) is recorded during the 2-minute test period. The body postures scored are slit stares, tail postures, scent marking of the cage/perches, piloerection, retreats, and arching of the back. Each animal is exposed to the threat stimulus twice on the test day before and after drug treatment. The difference between the two scores is analyzed using one-way analysis of variance followed by Dunnett's t-test. All drug treatments are carried out Sc at least 2 hours after the first (control) threat. The pretreatment time for each compound is 40 minutes. Rat Conflict Test Rats are trained to press levers for food reward in operant chambers. The schedule consists of alternations of four 4-minute unpunished periods on variable interval of 30 seconds signalled by chamber lights on and three 3-minute punished periods on fixed ratio 5 (by footshock concomitant to food delivery) signalled by chamber lights off. The degree of footshock is adjusted for each rat to obtain approximately 80% to 90% suppression of responding in comparison with unpunished responding. Rats receive saline vehicle on training days. The compounds of the instant invention are also expected to be useful in the treatment of pain and phobic disorders (Am. J. Pain Manag., 5:7-9 (1995)). The compounds of the instant invention are also expected to be useful in treating the symptoms of manic, acute or chronic, single upside, or recurring. They are also expected to be useful in treating and/or preventing bipolar disorder (U.S. Pat. No. 5,510,381). The compounds of the present invention can be prepared and administered in a wide variety of oral and parenteral dosage forms. Thus, the compounds of the present invention can be administered by injection, that is, intravenously, intramuscularly, intracutaneously, subcutaneously, intraduodenally, or intraperitoneally. Also, the compounds of the present invention can be administered by inhalation, for example, intranasally. Additionally, the compounds of the present invention can be administered transdermally. It will be obvious to those skilled in the art that the following dosage forms may comprise as the active component, either a compound of Formula I or a corresponding pharmaceutically acceptable salt of a compound of Formula I. For preparing pharmaceutical compositions from the compounds of the present invention, pharmaceutically acceptable carriers can be either solid or liquid. Solid form preparations include powders, tablets, pills, capsules, cachets, suppositories, and dispersible granules. A solid carrier can be one or more substances which may also act as diluents, flavoring agents, binders, preservatives, tablet disintegrating agents, or an encapsulating material. In powders, the carrier is a finely divided solid which is in a mixture with the finely divided active component. In tablets, the active component is mixed with the carrier having the necessary binding properties in suitable proportions and compacted in the shape and size desired. The powders and tablets preferably contain from five or ten to about seventy percent of the active compound. Suitable carriers are magnesium carbonate, magnesium stearate, talc, sugar, lactose, pectin, dextrin, starch, gelatin, tragacanth, methylcellulose, sodium carboxymethylcellulose, a low melting wax, cocoa butter, and the like. The term "preparation" is intended to include the formulation of the active compound with encapsulating material as a carrier providing a capsule in which the active component with or without other carriers, is surrounded by a carrier, which is thus in association with it. Similarly, cachets and lozenges are included. Tablets, powders, capsules, pills, cachets, and lozenges can be used as solid dosage forms suitable for oral administration. For preparing suppositories, a low melting wax, such as a mixture of fatty acid glycerides or cocoa butter, is first melted and the active component is dispersed homogeneously therein, as by stirring. The molten homogenous mixture is then poured into convenient sized molds, allowed to cool, and thereby to solidify. Liquid form preparations include solutions, suspensions, and emulsions, for example, water or water propylene glycol solutions. For parenteral injection liquid preparations can be formulated in solution in aqueous polyethylene glycol solution. Aqueous solutions suitable for oral use can be prepared by dissolving the active component in water and adding suitable colorants, flavors, stabilizing and thickening agents as desired. Aqueous suspensions suitable for oral use can be made by dispersing the finely divided active component in water with viscous material, such as natural or synthetic gums, resins, methylcellulose, sodium carboxymethylcellulose, and other well-known suspending agents. Also included are solid form preparations which are intended to be converted, shortly before use, to liquid form preparations for oral administration. Such liquid forms include solutions, suspensions, and emulsions. These preparations may contain, in addition to the active component, colorants, flavors, stabilizers, buffers, artificial and natural sweeteners, dispersants, thickeners, solubilizing agents, and the like. The pharmaceutical preparation is preferably in unit dosage form. In such form the preparation is subdivided into unit doses containing appropriate quantities of the active component. The unit dosage form can be a packaged preparation, the package containing discrete quantities of preparation, such as packeted tablets, capsules, and powders in vials or ampoules. Also, the unit dosage form can be a capsules, tablet, cachet, or lozenge itself, or it can be the appropriate number of any of these in packaged form. The quantity of active component in a unit dose preparation may be varied or adjusted from 0.1 mg to 1 g according to the particular application and the potency of the active component. In medical use the drug may be administered three times daily as, for example, capsules of 100 or 300 mg. The composition can, if desired, also contain other compatible therapeutic agents. In therapeutic use, the compounds utilized in the pharmaceutical method of this invention are administered at the initial dosage of about 0.01 mg to about 100 mg/kg daily. A daily dose range of about 0.01 mg to about 100 mg/kg is preferred. The dosages, however, may be varied depending upon the requirements of the patient, the severity of the condition being treated, and the compound being employed. Determination of the proper dosage for a particular situation is within the skill of the art. Generally, treatment is initiated with smaller dosages which are less than the optimum dose of the compound. Thereafter, the dosage is increased by small increments until the optimum effect under the circumstances is reached. For convenience, the total daily dosage may be divided and administered in portions during the day, if desired. The following examples are illustrative of the instant invention; they are not intended to limit the scope. EXAMPLE 1 ##STR18## General Method, Exemplified by Synthesis of Trans (R)-3-ethyl Gabapentin Step (i) Cyanoacetate A mixture of 3-(R)-Methylcyclohexanone (125 mmol), ethyl cyanoacetate (124 mmol), ammonium acetate (12.5 mmol) and glacial acetic acid (24 mmol) were refluxed with a Dean Stark trap for 24 hours. The mixture was cooled and washed with H 2 O. The H 2 O washes were extracted with toluene. The toluene extracts were combined with the original organic layer, dried over MgSO 4 , and the solvent evaporated. The crude oil was purified by Kugelrohr distillation to give an oil. Bpt oven temperature 150-160° C. Yield 86%. 1 H NMR (CDCl 3 ) 400 MHz: δ 1.01-1.05 (3H, m), 1.17-1.32 (1H, m), 1.35 (3H, t, J=7 Hz), 1.42-2.30 (6H, m), 2.98 (1H, d, J=13 Hz), 3.74 (1H, d, J=13 Hz), 4.27 (2H, q, J=7 Hz). MS (CI) m/z: 85, 91, 95, 135, 162, 178, 180, 200, 208 (100% MH + ), 209. IR (Film) υ max' cm -1 : 3437, 2956, 2930, 2870, 2223, 1729, 1603, 1448, 1367, 1347, 1313, 1290, 1262, 1246, 1218, 1101, 1084, 1046, 1023, 974, 957, 914, 859, 822, 780. ______________________________________Microanalysis: C.sub.12 H.sub.17 NO.sub.2 : Calc: C, 69.54; H, 8.27; N, 6.76. Found: C, 69.44; H, 8.22; N, 6.76.______________________________________ Step (ii) Bisnitrile To a solution of NaCN (40 mmol) in 6 mL H 2 O and 160 mL Ethanol (95%) was added the cyanoacetate (40 mmol). After 22 hours at reflux the cooled solution was filtered, the filtrate acidified with gaseous HCl, and filtered again. The solvent was removed, and the crude oil was purified by column chromatography to give a pale yellow crystalline solid. Yield 88% Mpt. 1 H NMR (CDCl 3 ) 400 MHz: δ 0.90 (1H, m), 0.98 (3H, d, J=6 Hz), 1.11 (1H, t, J=12 Hz), 1.38 (1H, dt, J=4.9 Hz), 160-190 (4H, m), 2.07 (2H, m), 2.68(2H, s). MS (CI) m/z: 91 (100%), 92, 108, 130, 136, 163, (50% MH + ), 180. IR (CH 2 Cl 2 ) υ max cm -1 : 2956, 2932, 2862, 2234, 1714, 1457, 1447, 1427, 1386, 1358. ______________________________________Microanalysis: C.sub.10 H.sub.14 N.sub.2 : Calc: C, 74.04; H, 8.70; N, 17.27. Found: C, 74.05; H, 8.71; N, 17.25.______________________________________ Step (iii) Imidate To a solution of the binitrile (6.2 mmol) in 30 mL ethanol (absolute) was added 30 mL dried toluene. The solution was chilled in ice while saturating with gaseous HCl. The stoppered solution was then left to stand at room temperature for 24 hours. The solvent was removed, and the solid residue was triturated with diethyl ether to obtain a ppt which was dried to give a white crystalline solid. Yield 50%. Mpt 118-120° C. 1 H NMR (DMSO) 400 MHz: δ 0.8-0.89 (1H, m), 0.91 (3H, d, J=6.3 Hz), 1.06-1.12 (1H, m), 1.24-1.35 (1H, m), 1.37 (3H, t, J=7 Hz), 1.41-1.95 (6H, mn), 3.02 (2H, s), 4.49 (2H, q, J=7 Hz). MS (CI) m/z: 91, 133, 154, 164, 179, 181, (100% MH + -CN), 195 (MH + ), 209. IR (CH 2 Cl 2 ) υ max cm -1 : 2957, 2938, 2858, 2233, 1651, 1573, 1446, 1388, 1361, 1137, 1103, 1022, 1005, 952, 933, 874, 834. ______________________________________Microanalysis: C.sub.12 H.sub.20 N.sub.2 O.1.08 HCl: Calc: C, 58.19; H, 8.58; N, 11.31. Found: C, 58.25; H, 8.59; N, 11.59.______________________________________ Step (iv) Ester The imidate (1.1 mmol) was dissolved in ice cold H 2 O (40 mL) and the pH adjusted with 1N HCl to pH 1.5. The solution was stirred at room temperature for hours. Ethylacetate was added (30 mL), and the organic layer was washed with H 2 O, dried, and the solvent removed to leave a clear oil. Yield 82%. 1 H NMR (CDCl 3 ) 400 MHz: δ 0.78-0.90 (1H, m), 0.93 (3H, d, J=6 Hz), 0.97-1.00 (1H, m), 1.23-1.25 (1H, m), 1.29 (3H, t, J=7.2 Hz), 1.59-1.80 (4H, m), 2.05-2.08 (2H, Br t), 2.54 (2H, s), 4.20 (2H, q, J=7.2 Hz). MS (CI) m/z: 88, 95, 109, 122, 137, 160, 164 (100% M + -EtOH), 182, 183, 199, 210 (60% MH + ), 230. IR (Film) υ max cm -1 : 2930, 2870, 2235, 1737, 1458, 1414, 1375, 1345, 1264, 1196, 1171, 1096, 1041, 1026, 959, 847. ______________________________________Microanalysis: C.sub.12 H.sub.19 NO.sub.2 : Calc: C, 68.87; H, 9.15; N, 6.69. Found: C, 68.87; H, 9.11; N, 6.90.______________________________________ Step (v) Lactam The ester (8.9 mmol) was dissolved in NH 3 /EtOH (7%, 40 mL) along with prewashed Raney Nickel (H 2 O followed by EtOH) in a 250 mL Parr flask. The solution was hydrogenated at 30° C., 46 psi for 24 hours. The cooled solution was filtered through a pad of celite, washing with ethylacetate. The solvent was removed from the filtrate to leave a white solid. Yield 30%. Mpt 92-98° C. 1 H NMR (DMSO) 400 MHz: δ 0.75-0.82 (1H, m), 0.84 (3H, d, J=6.4 Hz), 0.88-0.94 (1H, m), 1.14-1.19 (1H, m), 1.20-1.50 (2H, m), 1.50-1.63 (4H, m), 1.91 (2H, s), 3.03 (2H, s), 7.42 (1H, s). MS (CI) m/z: 166, 167, 168 (100% MH + ), 182, 196. IR (Film) υ max cm -1 : 3260, 2907, 1695, 1652, 1446, 1318, 1255, 1210, 1068. ______________________________________Microanalysis: C.sub.10 H.sub.17 NO: Calc: C, 71.81; H, 10.25; N, 8.37. Found: C, 71.80; H, 10.29; N, 8.31.______________________________________ Step (vi) 3-Methyl Gabapentin The lactam (2.17 mmol) was dissolved in a solution of 10 M HCl (5 mL) and H 2 O (5 mL), and the mixture was refluxed at approximately 140° C. for 5 hours. The cooled solution was diluted with 10 mL H 2 O and 10 mL DCM and the aqueous layer was further washed with 2×15 mL DCM. The aqueous layer was then reduced to dryness to leave a white solid. Yield 76%. Mpt 148-155° C. [α] D =-2.5 (T-20° C., c=1, MeOH). One isomer (RR). 1 H NMR (CDCl 3 ) 400 MHz: δ 06.9-0.79 (1H, m), 0.82 (3H, d, J=6 Hz), 0.87-0.90 (1H, m), 1.12-1.20 (1H, dt, J=4.5, 13.3 Hz), 1.34-1.50 (3H, m), 1.60-1.63 (3H, m), 2.30 (2H, s), 3.01 (2H, s), 7.93 (3H, Br s). MS (CI) m/z: 95, 109, 121, 151, 167, 168 (100% MH + -H 2 O), 186 (MH + ). IR (MeOH) υ max cm -1 : 2924, 2353, 1708, 1599, 1523, 1454, 1216. ______________________________________Microanalysis: C.sub.10 H.sub.19 NO.sub.2.1.1 HCl: Calc: C, 53.29; H, 8.99; N, 6.21. Found: C, 53.23; H, 8.99; N, 6.45.______________________________________ EXAMPLE 2 ##STR19## Cis/trans (RS)-2-methyl Gabapentin Step (i) Cyanoacetate (±)-2-Methylcyclohexanone (80 mmol), ethyl cyanoacetate (80 mmol), ammonium acetate (8 mmol), and glacial acetic acid (16 mmol) were reacted as in the general method Step (i), to give a clear oil. Yield 76%. Bpt oven temperature 120-140° C., 3 mbar. 1 H NMR (CDCl 3 ) 400 MHz: δ 1.23 (3H, dd, J=7, 10 Hz), 1.35 (3H, t, J=7 Hz), 1.55-1.82 (5H, m), 1.93-2.05 (1H, m), 2.17 (1H, dt, J=5, 14 Hz), 2.47 (1H, dt, J=5, 9 Hz), 2.92-2.97 (1H, Br d, J=15 Hz), 3.30-3.35 (1H, m), 3.81-3.86 (1H, Br d, J=15 Hz), 4.06-4.14 (1H, m), 4.23-4.30 (3H, dq, J=1, 6 Hz). MS (CI) m/z: 91, 105, 120, 162, 180, 184, 189, 208 (MH + ), 216, 233, 234, 242, 261, 262 (100%), 263. IR (Film) υ max cm -1 : 3438, 2978, 2938, 2864, 2223, 1732, 1596, 1463, 1447, 1391, 1368, 1334, 1311, 1289, 1247, 1224, 1164, 1144, 1103, 1077, 1058, 1032, 993, 982, 957, 907, 892, 858, 781. ______________________________________Microanalysis: C.sub.12 H.sub.17 NO.sub.2 : Calc: C, 69.54; H, 8.27; N, 6.76. Found: C, 69.26; H, 8.26; N, 6.66.______________________________________ Step (ii) Bisnitrile The cyanoacetate (37 mmol) and NaCN (37 imol) were reacted as in the general method Step (ii). The crude solid was purified by column chromatography (3:1, heptane:ethylacetate) to give a clear oil. Yield 76%. 1 H NMR (CDCl 3 ) 400 MHz: δ 1.06 (3H, d, J=6.8 Hz), 1.11 (3H, d, J=6.8 Hz), 1.20-2.20, (18 H, m), 2.77 (2H, dd, J=16.8 Hz), 2.63 (2H, dd, J=16.8 Hz). MS (CI) m/z: 91, 95, 108, 109, 136, 16.3 (100% MH + ). IR (Film) υ max cm -1 : 2939, 2865, 2255, 2237, 1750, 1720, 1450, 1425, 1387, 1356, 1337, 1316, 1269, 1160, 1097, 992, 929, 879. ______________________________________Microanalysis: C.sub.10 H.sub.14 N.sub.2.0.1 H.sub.2 O: Calc: C, 73.49; H, 8.69; N, 16.86. Found: C, 73.24; H, 8.73; N, 17.08.______________________________________ Step (iii) Imidate The binitrile (7.3 imol) was reacted as in the general method Step (iii) to give a white solid. Yield 70%. Mpt 107-114° C. 1 H NMR (DMSO) 400 MHz: δ 1.00-1.06 (3H, 2×t, J=6.4 Hz), 1.10-1.38 (2H, m), 1.38 (3H, t, J=6.8 Hz), 1.40-2.10 (7H, m), 2.86, 2.92, 3.10, 3.28 (2H, 4×d, J=14, 14.4, 14.8, 14 Hz, respectively), 4.48 (2H, q, J=6.8 Hz). MS (CI) m/z: 87, 95, 154, 163, 1.81, 195, 209 (100% MH + ), 210. IR (CH 2 Cl 2 ) υ max cm -1 : 2938, 2864, 2664, 2235, 1656, 1575, 1446, 1389, 1367, 1139, 1100, 1007, 948, 881, 837, 809. ______________________________________Microanalysis: C.sub.12 H.sub.20 N.sub.2 O.1.06 HCl: Calc: C, 58.37; H, 8.60; N, 11.34. Found: C, 58.15; H, 8.63; N, 11.60.______________________________________ Step (iv) Ester The imidate (4.1 mmol) was reacted as in the general method Step (iv) to give a clear oil. Yield 82%. 1 H NMR (CDCl 3 ) 400 MHz: δ 1.03, 1.09 (3H, 2×d, J=7 Hz), 1.27-1.30 (3H, m), 1.32-2.00 (8H, m), 2.10-2.20 (1H, m), 244, 2.82 (3H, 2×d, J=14.8 Hz), 2.54 (1H, m), 4.16-4.22 (2H, m). MS (Cl) m/z: 88, 95, 109, 122, 164, 182, 210 (MH + 100%). IR (Film) υ max cm -1 : 2936, 2864, 2234, 1737, 1449, 1418, 1385, 1372, 1345, 1270, 1225, 1186, 1128, 1098, 1029, 1001, 932, 883, 864, 808, 732. ______________________________________Microanalysis: C.sub.12 H.sub.19 NO.sub.2 : Calc: C, 68.87; H, 9.15; N, 6.69. Found: C, 68.84; H, 9.13; N, 6.75.______________________________________ Step (v) Lactam The ester (8.4 mmol) was reacted as in the general method Step (v) for 24 hours at 10° C., 50 psi. The crude oil was purified by column chromatography (ethylacetate), to give a white solid. Yield 34%. Mpt 85-90° C. 1 H NMR (CDCl 3 ) 400 MHz: δ 0.88-0.91 (3H, dd, J=4, 6.8 Hz), 1.41-1.78 (9H, m), 2.00-2.30 (2H, m) 3.06-3.23 (2H, m), 7.27 (1H, Br s). MS (CI) m/z: 81, 95, 108, 137, 166, 167, 168 (100 MH + ), 169, 182, 196. IR (CH 2 cl 2 ) υ max cm -1 : 3210, 2920, 2846, 1690, 1491, 1446, 1379, 1298, 1242, 1070. ______________________________________Microanalysis: C.sub.10 H.sub.17 NO: Calc: C, 71.81; H, 10.24; N, 8.37. Found: C, 71.83; H, 10.19; N, 8.27.______________________________________ Step (vi) 2-Methyl Gabapentin The lactam (2.5 mmol) was reacted as in the general method Step (vi) to give a white solid. Yield 42%. Mpt 108-110° C. [α] D =0 (T=20.5° C., C=1, MeOH). Two diastereomers 3:1. 1 H NMR (DMSO +D 2 O) 400 MHz: δ 0.79, 0.85 (3H, 2×d, J=6.8 Hz), 1.21-1.65 (9H, m), 2.22, 2.43 (1H, 2×d, J=15 Hz), 2.46, 2.49 (1H, 2×d, J=15 Hz), 2.83-2.92 (1H, 2×d, J=13.6 Hz), 3.05, 3.15 (1H, 2×d, J=13.6 Hz). MS (CI) m/z: 95, 109, 137, 166, 168 (100% lactam), 169 (MH + -H 2 O), 186 (MH+), 196. IR (MeOH) υ max cm -1 : 3384, 2931, 2861, 1703, 1608, 1506, 1456, 1406, 1232, 1206, 1068, 999. ______________________________________Microanalysis: C.sub.10 H.sub.19 NO.sub.2.1.3 HCl. Calc: C, 51.64; H, 8.79; N, 6.02. Found: C, 51.66; H, 8.91; N, 6.16.______________________________________ EXAMPLE 3 ##STR20## Step (i) Cyanoacetate The 4-Methylcyclohexanone (125 mmol), ethyl cyanoacetate (124 mmol), ammonium acetate (12.4 mmol), and glacial acetic acid (24.4 mmol) were reacted as in the general method Step (i) for 8 hours to give a clear oil. Yield 82%. Bpt oven temperature 160-190° C., 4 mbar. 1 H NMR (CDCl 3 ) 400 MHz: δ 0.95 (3H, d, J=6.8 Hz), 1.20-1.31 (2H, m), 1.35 (3H, t, J=7.2 Hz), 1.80-1.90 (1H, m), 1.90-2.10 (2H, m), 2.15 (1H, dt, J=4.8, 13.6 Hz), 2.34 (1H, dt, J=4.8, 13.6 Hz), 3.02 (1H, dd, J=2.4, 14 Hz), 3.84 (1H, dd, J=2.4, 14 Hz), 4.27 (2H, q, J=7.2 Hz). MS (CI) m/z: 114, 134, 151, 162, 179, 180, 207, 208 (100% MH + ), 209, 236. IR (Film) υ max cm -1 : 2927, 2225, 1728, 1601, 1456, 1367, 1288, 1242, 1192, 1095, 1028, 959, 857, 779. ______________________________________Microanalysis: C.sub.12 H.sub.17 NO.sub.2 : Calc: C, 69.54; H, 8.27; N, 6.76. Found: C, 69.39; H, 8.27; N, 6.77.______________________________________ Step (ii) Binitrile The cyanoacetate (30 mmol) and NaCN (30 mmol) were reacted as in the general method Step (ii) to give a crude oil. The oil was purified by column chromatography (3:1, heptane:ethylacetate) to give a clear oil. Yield 66%. 1 H NMR (CDCl 3 ) 400 MHz: δ 0.98 (3H, d, J=5.6 Hz), 1.30-1.40 (3H, m), 1.50 (2H, m), 1.73-1.92 (2H, m), 2.10 (2H, d, J=12.4 Hz), 2.68 (2H, s). MS (CI) m/z: 95, 136, 163 (100% MH + ), 164, 182. IR (Film) υ max cm -1 : 3628, 3288, 2932, 2859, 2252, 2238, 1779, 1748, 1721, 1626, 1455, 1423, 1381, 1371, 1332, 1287, 1263, 1194, 1170, 1143, 1109, 1004, 953, 893, 852. ______________________________________Microanalysis: C.sub.10 H.sub.14 N.sub.2.0.6 H.sub.2 O: Calc: C, 72.74; H, 8.74; N, 16.97. Found: C, 72.98; H, 8.61; N, 16.65.______________________________________ Step (iii) Imidate The binitrile (12.4 mmol) was reacted as in the general method Step (i) to give a slightly impure white solid. No purification was attempted, and solid was used in next step. Step (iv) Ester The imidate (4.7 mmol) was reacted as in the general method Step (iv) to give a low melting solid. Yield 75%, based on binitrile. 1 H-NMR (CDCl 3 ) 400 MHz: δ 0.92-1.01 (3H, m), 1.27-1.31 (3H, m), 1.37 (5H, m), 1.70-1.73 (2H, m), 2.10-2.13 (2H, m), 2.54 (2H, s), 4.21 (2H, q, J=7.2 Hz). MS (CI) m/z: 95, 112, 122, 164, 182 (100% MH + -C 2 H 5 ), 210 (MH + ). IR (CH 2 Cl 2 ) υ max cm -1 : 2926, 2856, 2235, 1735, 1733, 1452, 1373, 1345, 1253, 1191, 1033, 953. ______________________________________Microanalysis: C.sub.12 H.sub.19 N.sub.2 O.sub.2.0.12 H.sub.2 O: Calc: C, 68.16; H, 9.17; N, 6.62. Found: C, 68.14; H, 8.91; N, 6.77.______________________________________ Step (v) Lactam The ester (2.9 mmol) was reacted as in the general method Step (v) to give a white fibrous solid. Yield 95%. Mpt 150-152° C. 1 H NMR (DMSO) 400 MHz: δ 0.86 (3H, d, J=6 Hz), 0.93-1.06 (2H, m), 1.27-1.30 (3H, m), 1.51 (2H, d, J=11.6 Hz), 1.62 (2H, d, J=13.2 Hz), 1.92 (2H, s), 3.02 (2H, s), 7.43 (1H, Br s). MS (CI) m/z: 81, 95, 110, 166, 167, 168 (100% MH + ), 169, 182, 196. IR (CH 2 Cl 2 ) υ max cm -1 : 3189, 3093, 2945, 2921, 2864, 1679, 1486, 1447, 1417, 1260. ______________________________________Microanalysis: C.sub.10 H.sub.17 NO.0.15 H.sub.2 O: Calc: C, 70.67; H, 10.17; N, 8.24. Found: C, 70.69; H, 10.05; N, 7.87.______________________________________ Step (vi) 4-Methyl Gabapentin The lactam (2.5 mmol) was reacted as in the general method Step (vi) to give an off-white hygroscopic solid. Yield 92%. Mpt 146-151° C. [α] D =0 (T=21° C., C=1, MeOH). One diastereomer (cis). 1 H NMR (DMSO) 400 MHz: δ 0.88 (3H, d, J=6 Hz), 1.02-1.12 (2H, m), 1.25-1.32 (3H, m), 143-1.47 (2H, m), 2.33 (2H, s), 2.99 (2H, s), 8.03 (3H, Br s), 12.33 (1H, Br S). MS (CI) m/z: 81, 95, 109, 166, 167, 168 (100% MH + -H 2 O), 169, 182, 186 (MH + ), 196. IR (MeOH) υ max cm -1 : 3393, 2925, 2862, 1714, 1613, 1514, 1451, 1387, 1251, 1232, 1192, 1151, 1119, 864. ______________________________________Microanalysis: C.sub.10 H.sub.19 NO.sub.2.1 HCl.1 H.sub.2 O: Calc: C, 50.04; H, 9.26; N, 5.84. Found: C, 50.04; H, 9.18; N, 5.82.______________________________________ EXAMPLE 4 ##STR21## Cis 4-isopropyl Gabapentin Step (i) Cyanoacetate The 4-Isopropyl-cyclohexanone (57 mmol), ethylacetate (57 mmol), ammoninm acetate (58 mmol), and glacial acetic acid (11.3 mmol) were reacted as in the general method Step (i). Kugelrohr distillation gave a clear oil. Yield 83%. Bpt oven temperature 170-19° C., 4 mbar. 1 H NMR (CDCl 3 ) 400 MHz: δ 0.89 (6H, d, J=6.8 Hz), 1.20-1.33 (2H, m), 1.35 (3 H, t, J=7.2 Hz), 1.37-1.50 (2H, m), 2.00-2.11 (3H, m), 2.30 (1H, dt, J=5, 14 Hz), 3.10 (1H, m), 3.92 (1H, m), 4.27 (2H, q, J=7.2 Hz). MS (CI) m/z: 163, 179, 190, 207, 208, 235, 236 (100% MH + ), 237, 264. IR (Film) υ max cm -1 : 2959, 2871, 2225, 1730, 1603, 1448, 1387, 1368, 1291, 1264, 1239, 1214, 1190, 1140, 1101, 1029, 918, 852, 777. ______________________________________Microanalysis: C.sub.14 H.sub.21 NO.sub.2 : Calc: C, 71.46; H, 8.99; N; 5.95. Found: C, 71.28; H, 8.95; N, 5 90.______________________________________ Step (ii) Binitrile The cyanoacetate (37 mmol) and NaCN (37 mmol) were reacted as in the general method Step (ii) to give a yellow solid. Yield 100%. Mpt 79-81° C. 1 H NMR (CDCl 3 ) 400 MHz: δ 0.91 (6H, d, J=6.8 Hz), 1.00-1.20 (1H, m), 1.3-1.6 (5H, m), 1.85 (2H, d, J=12.8 Hz), 2.14 (2H, d, J=12 Hz), 2.70 (2H, m). MS (CI) m/z: 95, 121, 148, 164, 191 (100% MH + ), 192, 209, 210, 219, 231. IR (CH 2 Cl 2 ) υ max cm -1 : 2961, 2933, 2868, 2250, 2237, 1468, 1451, 1388, 1370, 1344, 1318, 1266, 1238, 1216, 1146, 1093, 1065, 1035; 998, 966, 934, 909, 738. ______________________________________Microanalysis: C.sub.12 H.sub.18 N2: Calc: C, 75.74; H, 9.53; N, 14.72. Found: C, 75.45; H, 9.51; N, 14.64.______________________________________ Step (iii) Imidate The binitrile (12.3 mmol) was reacted as in the general method Step (iii) to give a slightly impure white solid. No purification was attempted and solid was used in next step. Step (iv) Ester The imidate (4.4 mmol) was reacted as in the general method Step (iv) to leave a low melting solid. Yield 76% based on binitrile. 1 H NMR (CDCl 3 ) 400 MHz: δ 0.89 (6H, d, J=6.8 Hz), 0.91-1.04 (1H, m), 1.29 (3H, t, J=7 Hz), 1.33-1.51 (5H, m), 1.74-1.78 (2H, m), 2.14-2.17 (2H, m), 2.54 (2H,5), 4.17-4.22 (2H, q, J=7 Hz). MS (CI) m/z: 88, 123, 150, 192 (MH + -EtOH), 210 (MH + -CO), 238 (100% MH + ). IR (Film) υ max cm -1 : 2955, 2927, 2863, 2235, 1733, 1450. 1369, 1244, 1187, 1030, 933. ______________________________________Microanalysis: C.sub.14 H.sub.23 NO.sub.2.0.12 H.sub.2 O: Calc: C, 70.21; H, 9.78; N, 5.85. Found: C, 70.18; H, 9.82; N, 6.03.______________________________________ Step (v) Lactam The ester (2.9 mmol) was hydrogenated as in the general method Step (v) at 50° C., 50 psi, to give a crude solid. The solid was purified by column chromatography to give a white solid. Yield 38%. Mpt 130-134° C. 1 H NMR (CDCl 3 ) 400 MHz: δ 0.85-0.90 (6H, dd, J=0.8, 6.8 Hz), 1.00-1.05 (3H, m), 1.34-1.45 (3H, m), 1.63-1.65 (2H, m), 1.73-1.81 (2H, m), 2.13 (2H, d, J=0.8 Hz), 3.19 (2H, s), 5.91 (1H, Br s). MS (CI) m/z: 95, 152, 194, 195, 196 (100% MH + ), 197, 210, 224. IR (CH 2 Cl 2 ) υ max cm -1 : 3210, 3094, 2931, 2857, 1699, 1493, 1449, 1382, 1322, 1301, 1265, 919, 788. ______________________________________Microanalysis: C.sub.12 H.sub.21 NO: Calc: C, 73.80; H, 10.84; N, 7.77. Found: C, 73.83; H, 10.90; N, 7.11.______________________________________ Step (vi) 4-isopropyl Gabapentin The lactam (1 mmol) was reacted as in the general method Step (vi) to give a white powder. Yield 60%. Mpt 167-170° C. [α] D =0 (T=20° C., C=1, MeOH). One diastereomer (cis). 1 H NMR (DMSO) 400 MHz: δ 0.84 (6H, d, J=6.8 Hz), 0.90-1.00 (1H, m), 1.00-1.56 (2H, m), 1.23-1.30 (2H, m), 1.38-1.48 (3H, m), 1.66-1.70 (2H, m), 2.32 (2H, s), 2.97 (2H, s), 8.00 (3H, Br s), 12.00 (1H, Br s). MS (CI) m/z: 190, 196 (100% lactam H + ), 214 (MH + ). IR (MeOH) υ max cm -1 : 3557, 3144, 3027, 2949, 2865, 2354, 1712, 1591, 1507, 1455, 1468, 1409, 1322, 1286, 1246, 1199, 1077, 852. ______________________________________Microanalysis: C.sub.12 H.sub.23 NO.sub.2.1.12 HCl: Calc: C, 56.71; H, 9.57; N, 5.51. Found: C, 56.77; H, 9.56; N, 5.51.______________________________________ EXAMPLE 5 ##STR22## Step (i) 3,3-Dimethyl-cyclohexanone Synthesised via the method outlined by Pelletier S. W. and Mody N. V., J. Org. Chem., 41:1069 (1969). A solution of lithium dimethyl cuprate was prepared by the addition of methyl lithium (1.4 M in ether, 77.25 mL, 2.45 mol) to copper (I) iodide (8.8 g, 0.046 mol) under argon. The solution was cooled to 0° C., and 3-methyl-cyclohexen-1-one (5 mL, 0.044 mol) was added dropwise, with stirring, and a deep yellow precipitate was formed. The suspension was stirred at room temperature for 1 hour before being poured into a solution of aqueous ammonia (100 mL) and ammonium acetate (ca. 5 g). The layers were separated and the aqueous layer was washed with diethyl ether (3×50 mL). The combined organics were washed with saturated brine (3×100 mL), dried (Mgso 4 ), and the solvent removed in vacuo to leave a dark yellow liquid. 1 H NMR (CDCl 3 ) 400 MHz: 0.98 (6H, s, 2×Me), 1.59 (2H, m), 1.88 (2H, m), 2.14 (2H, m), 2.26 (2H, m). IR (Film) υ max cm -1 : 2956, 1711 (C═O), 1457, 1368, 1292, 1226, 1076. Step (ii) Cyanoacetate To a solution of 3,3-dimethyl-cyclohexanone (4 g, 0.032 mol) in toluene (25 mL) was added ethyl cyanoacetate (3.37 mL, 0.032 mol, 1 eq.), ammonium acetate (0.24 g, 0.003 mol, 0.1 eq.), and acetic acid (0.36 mL, 0.006 mol, 0.2 eq.). The yellow solution was heated to reflux while attached to a Dean-Stark trap, and heating was continued until no more water condensed in the trap. After cooling, the now orange solution was washed with water (3×2.5 mL) and the organic layer dried (MgSO 4 ). Filtration and removal of the solvent in vacuo gave the crude product as a deep orange liquid. Purification was achieved by Kugelrohr distillation to leave the mixture of cis and trans products as a pale yellow liquid, bp 160-170° C., 4 mbar (5.83 g, 83%). 1 H NMR (CDCl 3 ) 400 MHz: 0.96 (6H, s, 2×Me), 0.99 (6H, S, 2×Me), 1.34 (6H, m, 2×Me of ester), 1.49 (4H, m), 1.75 (2H, quin, J=6.4), 1.82 (2H, quin, J=6.4), 2.46 (2H, s), 2.60 (2H, t, J=6.4), 2.80 (2H, s) 2.93 (2H, t, J=6.4), 4.27 (4H, m, 2×CH2 ester). MS (CI) z/e: 222 (M + =1, 100%), 221 (5), 206 (4), 194 (6), 176 (5). IR (Film) υ max cm -1 : 2958, 2870, 2224 (CN), 1731 (C═O), 1606 (C═C), 1277, 1223. ______________________________________Microanalysis: C.sub.13 H.sub.19 O.sub.2 N: Calc: C, 70.56; H, 8.65; N, 6.32. Found: C, 70.35; H, 8.79; N, 6.25.______________________________________ Step (iii) Bisnitrile To a solution of the unsaturated cyanoester (1.26 g, 0.006 mol) in ethanol (100 mL) and water (4 mL) was added sodium cyanide (0.28 g, 0.006 mol, 1 eq.). The yellowish solution was heated to reflux for 8 hours and then cooled, during which time an off-white precipitate was formed. The suspension was filtered under vacuum and the filtrate acidified with HCl gas until the pH was approximately 2. The mixture was then filtered a second time and then the solvent removed in vacuo to leave the crude product as a pale green solid. Flash column chromatography, after absorption of the crude product on to silica, eluting with 0% to 50% EtOAc in heptane gave the binitrile as a colorless solid (0.57 g, 57%). 1 H NMR (CDCl 3 ) 400 MHz: 0.99 (3H, s, Me), 1.13 (1H, td, J=13.2, 4.2 Hz), 1.21 (3H, s, Me), 1.32 (2H, m), 1.54 (1H, m), 1.82 (3H, m), 2.15 (1H, m), 2.65 (2H, s, CH 2 CN). 13 C NMR (CDCl 3 ) 400 MHz: 19.61, 25.17, 30.79, 31.18, 33.77, 34.79, 35.37, 37.92, 46.26, 115.06, 122.19. MS (CI) z/e: 177 (M + +1, 100%), 161 (10), 150 (20), 136 (5), 120 (4), 109 (5). IR (Film) υ max cm -1 : 2988, 2937, 2869, 2237 (2×CN), 1749, 1456, 1423, 1369, 1202, 1180, 1031, 972. ______________________________________Microanalysis: C.sub.11 H.sub.16 N.sub.2 : Calc: C, 74.96; H, 9.15; N, 15.89. Found: C, 75.08; H, 9.32; N, 15.80.______________________________________ Step (iv) Cyanoester The binitrile (0.50 g, 2.84 mmol) was dissolved in absolute ethanol (20 mL) at room temperature and then cooled to 0° C. Toluene (20 mL) was added to the solution and then the reaction mixture was acidified by passing HCl gas through it at a gentle rate for ca. 45 minutes. The flask was then stoppered and left to stand at room temperature for 24 hours. The yellow solution was partitioned between ethyl acetate and water and the layers separated. The aqueous layer was extracted with ethyl acetate (3×30 mL), and the combined organics washed with aqueous saturated sodium hydrogen carbonate solution (3×50 mL), brine (3×50 mL), dried (MgSO 4 ), and the solvent removed under reduced pressure to leave a pale yellow liquid (0.59 g, 93%). 1 H NMR (CDCl 3 ) 400 MHz: 0.94 (3H, s, Me), 1.16 (3H, m), 1.21 (3H, s, Me), 1.29 (3H, t, J=7.2, CH 2 CH 3 ), 1.50 (1H, m), 1.65 (1H, dt, J=14.4, 7.6), 1.84 (1H, qt, J=13.3, 3.2), 1.96 (1H, dt, J=13.7, 2.2), 2.16 (1H, m), 2.48 (1H, d, J=15.6, C-2H), 2.54 (1H, d, J=15.6, C-2H), 4.20 (2H, q, J=7.2, CH 2 CH 3 ). 13 C NMR (CDCl 3 ) 400 MHz: 14.21, 19.65, 25.42, 31.03, 34.04, 34.14, 36.08, 38.44, 46.14, 46.80, 61.02, 123.67, 169.00. MS (CI) z/e: 224 (M + +1, 100%), 196 (12), 178 (35), 136 (13), 109 (12). IR (Film) υ max cm -1 : 2998 2937, 2868, 2234 (CN), 1738 (C═O), 1457, 1372, 1217, 1181, 1154, 1026. ______________________________________Microanalysis: C.sub.13 H.sub.21 NO.sub.2 : Calc: C, 69.92; H, 9.48; N, 6.27. Found: C, 69.63; H, 9.45; N, 6.15.______________________________________ Step (v) Lactam The cyanoester (0.5 g, 2.23 mmol) was hydrogenated in ethanolic ammonia (600 mL) with Raney nickel as catalyst (ca. 0.25 g) at 50° C. and 50 psi for 48 hours. The catalyst was then removed by filtration through Celite, and the solvent removed in vacuo to leave a greenish crystalline solid. Flash column chromatography, eluting with 0% to 100% ethyl acetate in heptane, gave the pure lactam as a colorless solid (340 mg, 84%). 1 H NMR (CDCl 3 ) 400 MHz: 0.89 (3H, s, Me), 0.92 (3H, s, Me), 1.25 (2H, m), 1.36 (2H, m), 1.51 (3H, m), 1.68 (1H, s), 2.18 (1H, d, J=16.4, CH 2 NH), 2.24 (1H, d, J=16.8, CH 2 NH), 3.15 (2H, s, CH 2 CO). 13 C NMR (CDCl 3 ) 400 MHz: 19.16, 29.88, 30.36, 31.28, 36.57, 39.05, 39.61, 44.58, 49.54, 54.79, 177.72. MS (CI) z/e: 182 (M + +1, 100%), 181 (15), 180 (5), 166 (3). IR (Film) υ max cm -1 : 3203, 3100 (NH), 2914, 2860, 1698 (C═O), 1486, 1374, 1317, 1289, 1257, 1076. ______________________________________Microanalysis: C.sub.11 H.sub.19 NO: Calc: C, 72.88; H, 10.56; N, 7.73. Found: C, 72.38; H, 10.47; N, 7.56.______________________________________ Step (vi) 3,3-Dimethyl Gabapentin Hydrochloride The lactam (0.3 g, 1.66 mmol) was dissolved in a mixture of HCl (concentrated, 5 mL) and water (5 mL), and the resultant colorless solution heated to reflux for 20 hours. The solution was cooled and then partitioned between water and dichloromethane, and the layers separated. The aqueous layer was washed with dichloromethane (3×20 mL) and the water/HCl removed by rotary evaporation to leave the crude product as an off-white solid. Trituration of this solid with ethyl acetate and filtration of the product gave 3,3-dimethylgabapentin, hydrochloride salt as a colorless solid (140 mg, 42%, 64% based on recovered starting material). 1 H NMR (DMSO) 400 MHz: 0.90 (3H, s, Me), 0.92 (3H, s, Me), 1.15-1.49 (8H, m), 2.45 (2H, s, CH 2 CO 2 H), 2.90 (2H, br q, J=13.5, CH 2 NH 3 ), 7.96 (3H, br s, NH 3 ), 12.36 (1H, br s, OH). IR (Film) υ max cm -1 : 2930, 1728 (C═O), 1272, 1123. ______________________________________Microanalysis: C.sub.11 H.sub.22 NO.sub.2 Cl: Calc: C, 56.04; H, 9.41; N, 5.94. Found: C, 55.79; H, 9.61; N, 6.23.______________________________________ EXAMPLE 6 ##STR23## Steps (i) and (ii) (R)-3-Methylcyclohexanone (10.92 mL, 89.2 mmol) was dissolved in methanol (25 mL) with ethylcyanoacetate (18.96 mL, 178 mmol) and cooled to 0° C. Ammonia gas was bubbled through the solution for 25 minutes, after which the solution was stoppered and stored at -20° C. After 66 hours, diethyl ether (100 mL) was added to the mixture, and the white solid which formed was filtered off, washed with diethyl ester (2×50 mL), and dried to give 15.71 g (67%) of a white solid. Without further purification, a sample of the solid (4.0 g, 15.3 mmol) was dissolved in concentrated H 2 SO 4 (40 mL) with gentle warming and allowed to stand overnight. Water (40 mL) was then cautiously added and the resulting mixture heated to 170° C. After 5 hours, all the solid had dissolved. The mixture was cooled to room temperature, diluted with water (200 mL), and extracted with diethyl ether (3×150 mL). The ether extracts were combined, dried over magnesium sulphate, and the solvent removed in vacuo. The oily residue was triturated with heptane to obtain a precipitate which was filtered off and dried to give 2.57 g (79%) of a buff colored solid. 1 H NMR (CDCl 3 ) 400 MHz: δ 0.85-0.94 (2H, m), 0.87 (3H, d, J=6 Hz), 1.15 (1H, m), 1.39-1.61 (3H, m), 1.71 (1H, br d, J=12.8 Hz), 1.87 (2H, m), 2.48 (2H, ABq, J=4 Hz), 2.67 (2H, s). MS (ES) z/e: 214 ([M] + , 13%), 213 (100%). IR (thin film) υ max cm -1 : 1204, 1290, 1413, 1458, 1702, 2924. ______________________________________Microanalysis: C.sub.11 H.sub.18 O.sub.4 : Calc: C, 61.66; H, 8.47. Found: C, 61.67; H, 8.51.______________________________________ Step (iii) Anhydride The diacid (2.5 g, 11.68 mmol) was heated to reflux in acetic anhydride (30 mL). After 3 hours, the solvent was removed in vacuo. The residue was dissolved in dichloromethane (50 mL) and washed with saturated aqueous sodium bicarbonate, dried (MgSO 4 ), and the solvent removed in vacuo to obtain 1.83 g (82%) of a brown oil. 1 H NMR (CDCl 3 ) 400 MHz: δ 0.84, 0.89 (3H, d, J=6 Hz), 0.98 (1H, m), 1.38-1.60 (4H, m), 1.64-180 (2H, m), 2.53 (2H, s), 2.74 (2H, s). MS (APCI+) z/e: 197 ([MH] + , 100%), 126 (32%). IR (thin film) υ max cm -1 : 947, 1073, 1181, 1761, 1810, 2925. ______________________________________Microanalysis: C.sub.11 H.sub.16 O.sub.3 :______________________________________Calc: C, 67.32; H, 8.22. Found: C, 66.98; H, 8.07.______________________________________ Step (iv) Half Ester, Cis/trans Mixture The anhydride (1.865 g, 9.5 mmol) was dissolved in dry methanol (10 mL) with sodium methoxide (0.5 M in MeOH, 20 mL, 10 mmol) and stirred at room temperature. After 3 hours the solvent was removed in vacuo and the residue partitioned between ethyl acetate (150 mL) and 1N HCl (50 mL). The organic phase was separated and the aqueous phase re-extracted with ethyl acetate (2×100 mL). The organic extracts were combined, dried (MgSO 4 ), and the solvent removed in vacuo to give 1.8 g (83%) of a pale brown oil which contained a -1:1 mixture of the cis and trans isomers. 1 H NMR (CDCl 3 ) 400 MHz: δ 0.85-0.93 (2H, m); 0.86 (3H, d, J=6 Hz); 1.17 (1H, m); 1.39-1.62 (3H, m); 1.64-1.80 (3H, m); 2.48 (2H, m); 2.64-2.65 (2H, 2×s one from each isomer). MS (ES-) z/e: 227 ([M-H] + , 100%). IR (thin film) υ max cm -1 : 1163, 1194, 1440, 1705, 1738, 2926, 3200. ______________________________________Microanalysis: C.sub.12 H.sub.20 O.sub.4 :______________________________________Calc: C, 63.13; H, 8.83. Found: C, 63.29; H, 8.83.______________________________________ Step (v) (1-Aminomethyl-3-methyl-cyclohexyl)-acetic Acid [(1s-(1α,3β)] The mixture of half ester isomers (515 mg, 2.26 mmol) was dissolved in acetone (6 mL) and cooled to -10° C. Triethylamine (377 μL, 2.7 mmol) was added followed by ethyl chloroformate (259 μL, 2.7 mmol). The mixture was stirred at -10° C. for 40 minutes, after which a solution of sodium azide (220 mg, 3.39 mmol) in water (1 mL) was added and the mixture allowed to warm to 0° C. After 40 minutes, the mixture was poured into ice cold water (20 mL) and extracted with ice cold toluene (3×20 mL). The toluene extracts were combined and dried over magnesium sulfate at 0° C. The toluene solution was then added dropwise into a flask preheated to 180° C. in an oil bath at 180° C. The solvent was removed via distillation. Once the addition was complete, the mixture was stirred at 180° C. for a further 20 minutes, until all the solvent had been removed. Dioxane (5 mL) and concentrated HCl (5 mL) were then added and the mixture refluxed for 3 hours. The mixture was then cooled to room temperature, diluted with water (30 mL), and washed with dichloromethane (2×30 mL). The aqueous phase was collected and the solvent removed in vacuo to give a brown gum, which was triturated with ethyl acetate to give a buff colored solid. The solid was recrystallized from a mixture of methanol, ethyl acetate, and heptane to yield 35 mg (7%) of a white solid. 1 H NMR (d 6 DMSO) 400 MHz: δ 0.70-0.88 (2H, m), 0.83 (3H, d, J=6 Hz), 1.06-1.17 (1H, m), 1.36-1.69 (6H, m), 2.44 (2H, s), 2.84 (2H, s), 7.92 (4H, br s). MS (ES+) z/e: 186 ([MH-HCl] + , 100%). IR (thin film) υ max cm -1 : 1211, 1408, 1709, :2925, 3200. ______________________________________Microanalysis: C.sub.10 H.sub.20 NO.sub.2 Cl · 0.25 H.sub.2______________________________________ O:Calc: C, 53.09; H, 9.13; N, 6.19; Cl, 15.67. Found: C, 53.24; H, 9.26; N, 6.23; Cl, 15.43.______________________________________ EXAMPLE 7 ##STR24## Cis/trans 3.5-dimethyl Gabapentin Steps (i) and (ii) Diacid Cis-3,5-dimethyl-cyclohexanone (11.24 g, 89.2 mmol) was dissolved in methanol (25 mL) ethyl cyanoacetate (18.96 mL, 178.2 mmol) and cooled to 0° C. Ammonia gas was then bubbled through the solution for 30 minutes. The solution was then stored at -20° C. After 66 hours, the solid was filtered off, washed with ether, and dried to yield 18.46 g (75%) of a white solid. Without further purification, a portion of the solid prepared above (6.0 g, 21.7 mmol) was dissolved in concentrated sulphuric acid (40 mL) with warming and left to stand overnight. Water (40 mL) was then cautiously added and the resulting solution heated to 180° C. After 5 hours, the mixture was cooled to room temperature, diluted with water (200 mL), and extracted with diethyl ether (3×150 mL). The organic extracts were combined, washed with brine, dried (MgSO 4 ), and the solvent removed in vacuo. The residue was triturated with heptane to obtain a solid which was recrystallized from a dichloromethane/heptane mixture to obtain 3.122 g (63%) of a buff colored solid. 1 H NMR (CDCl 3 ) 400 MHz: δ 0.49 (1H, m), 0.80 (2H, m), 0.87 (6H, d, J=6 Hz), 1.55-1.76 (3H, m), 1.85 (2H, br, d, J=13.2 Hz), 2.50 (2H, s), 2.67 (2H, s). MS (ES) z/e: 228 ([M] + , 14%), 227 ([M-H] + , 100%). IR (thin film) υ max cm -1 : 893, 1147, 1208, 1284, 1312, 1337, 1407, 1450, 1699, 2846, 2914, 2947, 3100. ______________________________________Microanalysis: C.sub.12 H.sub.20 O.sub.4 :______________________________________Calc: C, 63.13; H, 8.83. Found: C, 63.22; H, 8.95.______________________________________ Step (iii) Anhydride The diacid (3.0 g, 13.16 mmol) was dissolved in acetic anhydride (40 mL) and heated to reflux. After 3 hours, the mixture was cooled to room temperature and the solvent removed in vacuo. The residue was dissolved in dichloromethane (150 mL) and washed once with saturated aqueous sodium bicarbonate. The organic phase was separated, dried (MgSO 4 ), and the solvent removed in vacuo to obtain 2.60 g (94%) of a brown oil which solidified on standing. 1 H NMR (CDCl 3 ) 400 MHz: δ 0.53 (1H, m), 0.81-0.96 (2H, m, and 6H, d, J=6 Hz), 1.43-1.71 (4H, m), 1.76 (1H, m), 2.54 (2H, s), 2.73 (2H, s). MS (APCI+) z/e: 211 ([MH] + , 100%). IR (thin film) υ max cm -1 : 950, 1073, 1183, 1459, 1756, 1767, 1812, 2910, 2952. ______________________________________Microanalysis: C.sub.12 H.sub.18 O.sub.3 :______________________________________Calc: C, 68.55; H, 8.75. Found: C, 63.32; H, 8.75.______________________________________ Step (iv) Cis/trans Half Ester The anhydride (2.556 g, 12.17 mmol) was dissolved in dry methanol (15 mL) and stirred with in vacuo and the residue partitioned between 1N HCl (150 mL) and ethyl acetate (150 mL). The organic phase was separated, washed with brine, dried (MgSO 4 ), and the solvent removed in vacuo to give a yellow oil. This was purified by flash chromatography (silica, ethyl acetate:heptane, 1:1) to give 2.68 g (91%) of a colorless oil. 1 H NMR (CDCl 3 ) 400 MHz: δ 0.47 (2H, m), 0.82 (4H, m), 0.87 (12H, d, J=6 Hz), 1.57-1.80 (1OH, m), 2.46 (2H, s, isomer A), 2.48 (2H, s, isomer B), 2.63 (2H, s, isomer B), 2.64 (2H, s, isomer A), 3.67 (6H, s). MS (ES-) z/e: 241 ([M-H] + , 100%). IR (thin film) υ max cm -1 : 1163, 1197, 1437, 1459, 1706, 1736, 2913, 2951, 3100. ______________________________________Microanalysis: C.sub.13 H.sub.22 O.sub.4 :______________________________________Calc: C, 64.44; H, 9.15. Found: C, 64.17; H, 9.17.______________________________________ Step (v) Cis/trans-3.5-Dimethyl Gabapentin The cis/trans mixture of half esters (1.09 g, 4.5 mmol) was dissolved in acetone (15 mL) and cooled to -10° C. Triethylamine (predried over lithium aluminum hydride) (660 μL, 4.74 mmol) was then added followed by ethyl chloroformate (453 μL, 4.764 mmol). After 40 minutes at 10° C., a solution of sodium azide (337 mg, 5.19 mmol) in water (2.5 mL) was added and the mixture allowed to warm to 0° C. After 40 minutes, the mixture was poured into ice cold water (30 mL) and extracted with ice cold toluene (3×20 mL). The organic extracts were combined, dried (MgSO 4 ), and stored at 0° C. The toluene solution was then added dropwise to a flask set up for distillation in an oil bath set at 180° C. The solvent was removed by distillation during the additions. After the addition was complete, the mixture was stirred at 180° C. for 1 hour, after which a gentle stream of nitrogen was passed through the apparatus to remove the last traces of solvent. Hydrochloric acid (75% v/v, 20 ml,) was then added cautiously, and the resulting solution refluxed for 3 hours. The mixture was cooled to room temperature and stored at room temperature overnight. The mixture was diluted with water (20 mL) and extracted with dichloromethane (2×15 mL). The aqueous phase was collected and the solvent removed in vacuo. The residue was triturated with ethyl acetate to obtain 255 mg (24%) of a white solid. 1 H NMR (d 6 DMSO) 400 MHz: δ 0.46 (2H, m), 0.76-0.90 (16H, m), 1.50-1.70 (10H, m), 2.30 (2H, s, isomer A), 2.44 (2H, s, isomer B), 2.84 (2H, s, isomer B), 3.00 (2H, s, isomer A), 7.91 (6H, br s), 12.40 (2H, br s). MS (ES+) z/e: 200 ([MH-HCl] + , 100%). IR (thin film) υ max cm -1 : 1201, 1458, 1715, 2949, 3200. ______________________________________Microanalysis: C.sub.11 H.sub.22 NO.sub.2 Cl:______________________________________Calc: C, 56.04; H, 9.41; N, 5.94. Found: C, 55.75; H, 9.46; N, 5.87.______________________________________ EXAMPLE 8 ##STR25## Cis/trans 4-methyl Gabapentin Steps (i) and (ii) Diacid 4-Methylcyclohexanone (5 mL, 40.74 mmol) was dissolved in methanol (15 mL) with ethyl cyanoacetate (8.67 mL, 81.48 mmol) and cooled to 0° C. Ammonia gas was bubbled through the solution for 25 minutes, after which the solution was stoppered and stored at -20° C. After 20 hours, diethyl ether (100 mL) was added to the mixture, and the white solid which formed was filtered off, washed with diethyl ether (2×50 mL), and dried to give 7.51 g (70%) of a white solid. Without further purification, a sample of the solid (4.0 g, 15.3 mmol) was dissolved in concentrated H 2 SO 4 (40 mL) with gentle warming and allowed to stand overnight. Water (40 mL) was then cautiously added and the resulting mixture heated to 170° C. After 3 hours, all the solid had dissolved. The mixture was cooled to room temperature, diluted with water (150 mL), and extracted with diethyl ether (3×100 mL). The ether extracts were combined, dried over magnesium sulphate, and the solvent removed in vacuo. The oily residue was triturated with heptane to obtain a precipitate which was filtered off and dried to give 2.3 g (73%) of a buff colored solid. 1 H NMR (d 6 DMSO) 400 MHz: δ 0.87 (3H, d, J=6 Hz); 1.1 (2H, m); 1.27 (3H, m); 1.44 (2H, m); 1.70 (2H, br d, J=13 Hz); 2.34 (2H, s); 2.45 (2H, s). MS (ES-) z/e: 214 ([M] + , 13%), 213 ([M-H) + , 100%). IR (thin film) υ max cm -1 : 917, 1183, 1215, 1289, 1349, 1399, 1455, 1704, 2858, 2925, 3100. ______________________________________Microanalysis: C.sub.11 H.sub.18 O.sub.4 :______________________________________Calc: C, 61.66; H, 8.47. Found: C, 61.54; H, 8.47.______________________________________ Step (iii) Anhydride The diacid (2.30 g, 10.75 mmol) was heated to reflux in acetic anhydride (30 mL). After 3.5 hours, the solvent was removed in vacuo. The residue was dissolved in dichloromethane (50 mL) and washed with saturated aqueous sodium bicarbonate, dried (MgSO 4 ), and the solvent removed in vacuo to obtain 2.07 g (98%) of a brown oil which solidified on standing. 1 H NMR (CDCl 3 ) 400 MHz: δ 0.93 (3H, d, J=6 Hz), 1.07 (2H, m), 1.37 (3H, m), 1.49-1.71 (4H, m), 2.56 (2H, s), 2.72 (2H, s). MS (APC1+) z/e: 197 ([MH] + , 100%). IR (thin film) υ max cm -1 : 953, 1064, 1183, 1241, 1455, 1761, 1810, 2924. ______________________________________Microanalysis: C.sub.11 H.sub.16 N.sub.3 :______________________________________Calc: C, 67.32; H, 8.22. Found: C, 67.41; H, 8.29.______________________________________ Step (iv) Cis/trans Half Ester The anhydride (2.06 g, 10.5 mmol) was dissolved in dry methanol (40 mL) and stirred with sodium methoxide (624 mg, 11.55 mmol). After 4 hours, the solvent was removed in vacuo and the residue partitioned between 1N HCl (150 mL) and dichloromethane (150 mL). The organic phase was separated, washed with brine, dried (MgSO 4 ), and the solvent removed in vacuo to give a yellow oil. This was purified by flash chromatography (silica, ethyl acetate:heptane, 1:1) to give 1.98 g (83%) of a colorless oil. 1 H NMR (CDCl 3 ) 400 MHz: δ 0.83-0.92 (2H, m), 0.91 (6H, d, J=6 Hz), 1.14 (4H, m), 1.21-1.42 (4H, m), 1.54 (4H, m), 1.77 (4H, m), 2.49 (2H, s, isomer A), 2.50 (2H, s, isomer B), 2.62 (2H, s, isomer B), 2.64 (2H, s, isomer A), 3.66 (3H, s, isomer A), 3.67 (3H, s, isomer B). MS (ES-) z/e: 227 ([M-H] + , 100%). IR (thin film) υ max cm -1 : 1162, 1193, 1434, 1699, 1731, 2922, 3200. ______________________________________Microanalysis: C.sub.12 H.sub.20 O.sub.4 :______________________________________Calc: C, 63.13; H, 8.83. Found: C, 63.12; H, 8.71.______________________________________ Step (v) Cis/trans 4-methyl Gabapentin The cis/trans mixture of half esters (1.90 g, 8.3 mmol) was dissolved in acetone (20 mL) and cooled to -10° C. Triethylamine (predried over lithium aluminium hydride) (1.21 mL, 8.7 mmol) was then added followed by ethyl chloroformate (832 μL, 8.7 mmol). After 50 minutes at -10° C., a solution of sodium azide (630 mg, 9.69 mmol) in water (5 mL) was added and the mixture allowed to warm to 0° C. After 40 minutes, the mixture was poured into ice cold water (50 mL) and extracted with ice cold toluene (3×50 mL). The organic extracts were combined, dried (MgSO 4 ), and kept at 0° C. The toluene solution was then added dropwise to a flask set up for distillation in an oil bath set at 180° C. The solvent was removed by distillation during the addition. After the addition was complete, the mixture was stirred at 180° C. for 1 hour, after which a gentle stream of nitrogen was passed through the apparatus to remove the last traces of solvent. Hydrochloric acid (75% v/v, 40 mL) was then added cautiously, and the resulting solution refluxed for 3 hours. The mixture was cooled to room temperature and sorted at room temperature overnight. The mixture was diluted with water (30 mL) and extracted with dichloromethane (3×30 mL). The aqueous phase was collected and the solvent removed in vacuo. The residue was triturated with ethyl acetate to obtain 590 mg (32%) of a white solid. 1 H NMR (d 6 DMSO) 400 MHz: δ 0.87 (6H, d, J=6 Hz), 1.07 (4H, m), 1.19-1.40 (6H, m), 1.41-1.58 (6H, m), 1.61 (2H, m), 2.32 (2H, s, isomer A), 2.44 (2H, s, isomer B), 2.85 (2H s, isomer B), 2.99 (2H, s, isomer A), 7.96 (6H, br s), 12.36 (2H br s). MS (ES+) z/e: 186 ([MH-HCl] + , 100%). IR (thin film) υ max cm -1 : 1195, 1404, 1457, 1506, 1607, 1712, 2924, 3200. ______________________________________Microanalysis: C.sub.10 H.sub.20 NO.sub.2 Cl:______________________________________Calc: C, 54.17 H, 9.09; N, 6.32. Found: C, 54.13; H, 9.18; N, 6.45.______________________________________

Substituted cyclic amino acids of formula ##STR1## are disclosed and are useful as agents in the treatment of epilepsy, faintness attacks, hypokinesia, cranial disorders, neurodegenerative disorders, depression, anxiety, panic, pain, and neuropathological disorders. Processes for the preparation and intermediates useful in the preparation are also disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS This application claims benefit of U.S. provisional patent application with Ser. No. 60/073,843, filed Feb. 5, 1998; and U.S. provisional patent application with Ser. No. 60/084,377, filed on May 6, 1998 and entitled “Compliant Semiconductor Chip Package with Fan-out Leads and Method of Making Same”, the disclosures of which are incorporated by reference herein. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the art of electronic packaging, and more specifically to assemblies incorporating microelectronic components and methods of making such assemblies. 2. Description of the Related Art In attempting to use the area on printed wiring boards more efficiently, semiconductor chip manufacturers have switched some of their production from larger more cumbersome interconnection conventions, such as pin grid arrays and perimeter leaded quad flat packs, to smaller conventions such as ball grid arrays (“BGA”) and chip scale packages (“CSP”). Using BGA technology, semiconductor chips are typically interconnected to an external substrate, such as a printed circuit board, using solder connections, such as with “flip-chip” technology. However when solder alone is used to interconnect the chip contact to the external substrate, the columns of solder are generally designed to be short to maintain the solder's structural integrity. This results in minimal elastic solder connections properties which further results in increased susceptibility to solder cracking due to mechanical stress caused by the differential coefficient of thermal expansion (“CTE”) of the chip relative to the external substrate thereby reducing the reliability of the solder connection. In other words, when the chip heats up during use, both the chip and the external substrate expand; and when the heat is removed, both the chip and the external substrate contract. The problem that arises is that the chip and the external substrate expand and contract at different rates and at different times, thereby stressing the interconnections between them. As the features of the semiconductor chips continue to be reduced in size, the number of chips packed into a given area will be greater and the heat dissipated by each of these chips will have a greater effect on the thermal mismatch problem. This further increases the need for a highly compliant scheme for interconnecting each chip to the external substrate. Such an interconnection scheme must also be capable of accommodating a large number of interconnection between a single semiconductor chip and an external substrate, such as a printed circuit board. Complex microelectronic devices such as modem semiconductor chips require numerous connections to other electronic components. For example, a complex microprocessor chip may require many hundreds of connections to an external substrate. Semiconductor chips commonly have been connected to electrical traces on mounting substrates by one of three methods: wire bonding, tape automated bonding and flip-chip bonding. In wire bonding, the semiconductor chip is positioned on a substrate with one surface of the chip abutting the substrate and the face or contact bearing surface of the chip facing upward, away from the substrate. Individual gold or aluminum wires are connected between the contacts on the semiconductor chip and the current conducting pads on the substrate. In tape automated bonding, a flexible dielectric tape with a prefabricated array of leads thereon is positioned over the semiconductor chip and substrate, and the individual leads are bonded to the contacts and pads. In both wire bonding and conventional tape automated bonding, the current conducting pads on the substrate are arranged outside the area covered by the semiconductor chip, so that the wires or leads “fan-out” from the chip to the surrounding current conducting pads. The area covered by the subassembly is considerably larger than the area covered by chip. Because the speed with which a semiconductor chip package can operate is inversely related to its size, this presents a serious drawback. Moreover, the wire bonding and tape automated bonding approaches are generally most workable with semiconductor chips having contacts disposed in rows extending along the periphery of the chip. They generally do not lend themselves to the use of chips having contacts disposed in a so-called area array, i.e., a grid-like pattern covering all or a substantial portion of the chip face surface. In the flip-chip mounting technique, the contact-bearing surface of the semiconductor chip faces towards the substrate. Each contact on the semiconductor chip is joined by a solder bond to the corresponding current carrying pad on the substrate, as by positioning solder balls on the substrate or contacts on the semiconductor chip, juxtaposing the chip with the substrate in the face-down orientation and momentarily melting or reflowing the solder. The flip-chip technique yields a compact assembly, which occupies an area of the substrate no larger than the area of the chip itself. However, flip-chip assemblies suffer from significant problems with thermal stress. The solder bonds between the contacts on the semiconductor chip and the current carrying pads on the substrate are substantially rigid. Changes in the size of the chip and the substrate due to thermal expansion and contraction in service create substantial stresses in these rigid bonds, which in turn can lead to fatigue failure of the bonds. Moreover, it is difficult to test the semiconductor chip before attaching it to the substrate and hence difficult to maintain the required outgoing quality level in the finished assembly, particularly where the assembly includes numerous semiconductor chips. Numerous attempts have been made to solve the foregoing problems. Useful CSP solutions are disclosed in commonly assigned U.S. Pat. Nos. 5,148,265; 5,148,266; 5,455,390; 5,477,611; 5,518,964; 5,688,716; and 5,659,952, the disclosures of which are incorporated herein by reference. In preferred embodiments, the structures disclosed in U.S. Pat. Nos. 5,148,265 and 5,148,266, incorporate flexible, sheet-like structures referred to as “interposers” or “chip carriers”. The preferred chip carrier has a plurality of terminals disposed on a flexible, sheet-like top layer. In use, the interposer is disposed on the contact-bearing surface of the chip with the terminals facing upwardly, away from the chip. The terminals are then connected to the contacts on the chip. Most preferably, this connection is made by bonding prefabricated leads on the interposer to contacts on the chip, using a tool engaged with the leads. The completed assembly is then connected to a substrate, as by bonding the terminals of the chip carrier to the substrate. Because the leads and the dielectric layer of the chip carrier are flexible, the terminals on the chip carrier can move relative to the contacts on the chip without imposing significant stresses on the bonds between the leads and the contacts on the chip or on the bonds between the terminals of the chip carrier and the substrate. Thus, the assembly can compensate for thermal effects. Moreover, the assembly most preferably includes a compliant layer disposed between the terminals on the chip carrier and the face of the semiconductor chip itself as, for example, an elastomeric layer incorporated in the chip carrier and disposed between the dielectric layer of the chip carrier and the semiconductor chip. Such a compliant structure permits displacement of the individual terminals independently towards the chip and also facilitates movement of the terminals relative to the chip in directions parallel to the chip surface. The compliant structure further enhances the resistance of the assembly to thermal stresses during use and facilitates engagement between the subassembly and a test fixture during manufacturing. Thus, a test fixture incorporating numerous electrical contacts can be engaged with all of the terminals in the subassembly despite minor variations in the height of the terminals. The substrate can be tested before it is bonded to a substrate so as to provide a tested, known-good part to the substrate assembly operation. This in turn provides very substantial economic and quality advantages. U.S. Pat. No. 5,455,930 describes a further improvement. Components according to preferred embodiments of the '930 patent use a flexible, dielectric top sheet. A plurality of terminals are mounted on the top sheet. A support layer is disposed underneath the top sheet, the support layer having a bottom surface remote from the top sheet. A plurality of electrically conductive, elongated leads are connected to the terminals on the tip sheet and extend generally side by side downwardly from the terminals through the support layer. Each lead has lower end at the bottom surface of the support layer. The lower ends of the leads have conductive bonding materials as, for example, eutectic bonding metals. The support layer surrounds and supports the leads. Components of this type can be connected to microelectronic elements, such as semiconductor chips or wafers by juxtaposing the bottom surface of the support layer with the contact-bearing surface of the chip so as to bring the lower ends of the leads into engagement with the contacts on the chip, and then subjecting the assembly to elevated temperature and pressure conditions. All of the lower ends of the leads bond to the contacts on the semiconductor chip substantially simultaneously. The bonded leads connect the terminals on the top sheet with the contacts on the chip. The support layer desirable is either formed from a relatively low-modulus, compliant material, or else is removed and replaced after the lead bonding step with such a compliant material. In the finished assembly, the terminals on the relatively flexible dielectric top sheet desirably are moveable with respect to the contacts on the semiconductor chip to permit testing of and to compensate for thermal effects. The component and the methods of the '930 patent provide further advantages, including the ability to make all of the bonds to the chip or other component in a single lamination-like process step. U.S. Pat. No. 5,518,964 discloses still further improvements. Preferred methods according to the '964 patent, include the step of providing a dielectric connection component having a plurality of terminals and a plurality of leads. Each lead has terminal-end attached to one of the terminals and a tip end (or contact-end) attached to a contact on a chip. Preferred methods also include the step of simultaneously forming all of the leads by moving all of the tip ends of the leads relative to the terminal-ends thereof and relative to the dielectric connection component so as to bend the tip ends away from the dielectric connection component. The dielectric connection component and the chip desirably move in vertical and horizontal directions relative to each other so as to deform the leads towards positions in which the leads extend generally vertically downward, away from the dielectric connection component. The method may also include the step of injecting a flowable compliant dielectric material around the leads. The terminals can be connected to an external substrate, such as a printed circuit board, to thereby provide electrical current communication to the contacts on the chip. Each terminal structure is movable with respect to the contacts on the chip in horizontal directions parallel to the chip, as well as in vertical directions towards and away from the chip, to accommodate differences in thermal expansion and contraction between the chip and the external substrate and to facilitate testing and assembly. The finished assembly can be mounted within an area of an external substrate substantially the same as that required to mount a bare chip. U.S. Pat. No. 5,477,611 discloses a method of creating an interface between a chip and chip carrier including spacing the chip a give distance above the chip carrier and introducing a liquid in the gap between the chip and the carrier. Preferably, the liquid is an elastomer that is cured into a resilient layer after its introduction into the gap. In another preferred embodiment, the terminals on a chip carrier are planarized or otherwise vertically positioned by deforming the terminals into set vertical locations with a plate, and a liquid is then cured between the chip carrier and the chip. U.S. Pat. No. 5,688,716 discloses a method of making a semiconductor chip assembly having fan-out leads. The method includes the step of providing a semiconductor chip and a package element attached to the chip. The peripheral region of the package element projects beyond the outer edge of the chip. A dielectric element having terminals on its top surface is positioned over the chip and package element such that a central region of the dielectric element overlies the chip and a peripheral region of the dielectric having at least some of the terminals thereon overlies the peripheral region of the package element. The assembly also has leads that are attached to contacts on the chip and to the terminals on the dielectric element. The method also comprises the step of moving the dielectric element and chip relative to one another such that the leads are bent into a flexible configuration. The method also comprises the step of injecting a liquid beneath the dielectric element and curing such liquid to form a compliant layer. U.S. Pat. No. 5,659,952 discloses a method of fabricating a compliant interface for a semiconductor chip. The method includes the steps of providing a first support structure, such as a flexible dielectric sheet, having a porous resilient layer thereon. The resilient layer may be a plurality of compliant pads or compliant spacers. A second support element, such as a semiconductor chip, is abutted against the resilient layer and a curable liquid is disposed within the porous resilient layer. The curable liquid may then be cured to form a compliant layer. Despite the positive results of the aforementioned commonly owned inventions, still further improvements would be desirable. SUMMARY OF THE INVENTION The present invention relates to compliant semiconductor chip packages and to methods of making such packages. The semiconductor chip package according to one embodiment of the present invention comprises a dielectric element with a plurality of electrically conductive terminals, an expander ring connected to the dielectric element, a semiconductor chip disposed within a central opening in the expander ring, and fan-in and fan-out leads connecting the terminals to contacts on the semiconductor chip. Semiconductor chip packages having fan-in leads are disclosed in commonly assigned U.S. Pat. No. 5,258,330, the disclosure of which is incorporated herein by reference. Semiconductor chip packages having fan-out leads and semiconductor chip packages having both fan-in and fan-out leads are disclosed in commonly assigned U.S. Pat. No. 5,679,977, the disclosure of which is incorporated herein by reference. The package also comprises an encapsulant disposed in the gap between the expander ring and the semiconductor chip. The size of the gap is controlled to minimize the pressure exerted on the leads by the encapsulant as it expands and contracts in response to changes in temperature. The semiconductor chip and expander ring may also be connected to a heat sink or thermal spreader with a compliant adhesive. The present invention also relates to a method of making a semiconductor chip package. The method comprises the steps of providing a dielectric element, disposing a compliant layer over the dielectric element, disposing a semiconductor chip over the compliant layer, disposing an expander ring over the compliant layer such that a gap is formed between the inner diameter of a central opening in the expander ring and the outer periphery of the semiconductor chip, and electrically interconnecting terminals on the dielectric element to contacts on the semiconductor chip. If the package is to include a thermal spreader, such thermal spreader can be attached to the semiconductor chip and/or the expander ring with an adhesive. If the coefficient of thermal expansion (hereinafter “CTE”) of the thermal spreader and the CTE of the semiconductor chip are not matched, then the adhesive should be a compliant adhesive. In preferred embodiments, the thermal spreader is attached before the contacts and the terminals are electrically interconnected. In preferred embodiments, the semiconductor chip package is encapsulated by injecting a liquid composition, which is curable to an elastomeric encapsulant, into the open spaces between the dielectric element, the semiconductor chip, the expander ring and the optional thermal spreader, including the gap between the outer periphery of the semiconductor chip and the inner diameter of the central opening of the expander ring. The compliant adhesive, the compliant layer and the encapsulant may be comprised of the same or different materials. Prior to injecting the liquid composition, it is desirable to seal the package by adhering a coverlay to the bottom surface of the dielectric element. The coverlay preferably has a plurality of holes which are dispose over and aligned with the terminals on the dielectric element. If a thermal spreader is used and the thermal spreader has relief slots, it is also desirable to adhere a protective film over the thermal spreader to seal such slots. A plurality of solder balls may be attached to the terminals. The semiconductor chip package can be connected to an external circuit via such solder balls. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of one embodiment of the semiconductor chip assembly of the present invention. FIG. 2 is a side view of another embodiment of the semiconductor chip assembly of the present invention. FIG. 3 is a side view of another embodiment of the semiconductor chip assembly of the present invention. FIG. 4 is a side view of another embodiment of the semiconductor chip assembly of the present invention. FIG. 5 is a side view of another embodiment of the semiconductor chip assembly of the present invention. FIG. 6 is a side view of another embodiment of the semiconductor chip assembly of the present invention. FIG. 7 is a side view of another embodiment of the semiconductor chip assembly of the present invention. FIGS. 8A-8S show views of a plurality of semiconductor chip packages in progressive steps in a manufacturing process according to one embodiment of the method of the present invention. FIGS. 8A, 8 B, 8 C, 8 E are top plan view of such packages in various steps in such manufacturing process. FIG. 8D is a top plan view of a component used in such manufacturing process. FIG. 8F is a bottom plan view of another component used in such manufacturing process. FIG. 8G is a top plan view of such packages after the component of FIG. 8F has been adhered to such packages. FIG. 8H is a bottom plan view of the packages in progress after the manufacturing step described in FIG. 8G has been completed. FIG. 8I is an exploded view of a portion of FIG. 8 H. FIG. 8J is a bottom plan view of the packages in progress after another manufacturing process step has been completed. FIG. 8K is an exploded view of a portion of FIG. 8 J. FIG. 8L is a bottom plan view of another component used in such manufacturing process. FIG. 8M is a bottom plan view of the packages in process after the component of FIG. 8L has been adhered to such packages. FIG. 8N is a top plan view of another component used in such manufacturing process. FIG. 8O is a top plan view of the packages in process after the component of FIG. 8N has been adhered to such packages. FIGS. 8P-8S are bottom plan view of such packages in various steps in such manufacturing process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As depicted in FIG. 1, the semiconductor chip assembly 1 according to one aspect of the present invention includes a semiconductor chip 2 , an expander ring 7 and a dielectric element 5 . Semiconductor chip 2 has a face surface 15 , a back surface 16 opposite the face surface, and four side surfaces 17 (two of which are visible in FIG. 1) which connect the face surface to the back surface. The four side surfaces form the outer perimeter of semiconductor chip 2 . Expander ring 7 has a first surface 20 , a second surface 21 opposite the first surface, and four inner side walls 22 (two of which are visible in FIG. 1) which define a central opening. Dielectric element 5 has a top surface 18 , a bottom surface 19 opposite top surface 18 , and a plurality of apertures 6 . Top surface 18 is comprised of a central region, which is disposed beneath the face surface 15 of semiconductor chip 2 , and a peripheral region that surrounds the central region. Descriptors such as “top”, “bottom”, “beneath”, etc, should be understood to refer to the drawing in FIG. 1 and not to any gravitational frame of reference. In preferred embodiments dielectric element 5 is flexible. Expander ring 7 is disposed over dielectric element 5 such that second surface 21 confronts the peripheral region of the top surface 18 of dielectric element 5 . The CTE of the dielectric element is preferably from 15 to 22 ppm/° C., inclusive. The CTE of the expander ring is preferably from 5 to 30 ppm/° C., inclusive. Semiconductor chip 2 is disposed within the central opening of expander ring 7 such that a gap 8 is formed between the outer perimeter of semiconductor chip 2 and the four inner side walls 22 of the central opening of expander ring 7 . A compliant layer 11 is disposed between face surface 15 of semiconductor chip 2 and top surface 18 of dielectric element 5 . The CTE of the compliant layer is preferably from 100 to 300 ppm/° C., inclusive. An adhesive 27 is disposed between the expander ring 7 and the dielectric element 5 . An encapsulant 3 is disposed within gap 8 . In preferred embodiments, W≧(CTE expander ring −CTE chip )X c )/(CTE encapsulant (1+2p)); where w is the width of gap 8 ; CTE expander ring is the coefficient of thermal expansion of the expander ring; CTE chip is the coefficient of thermal expansion of the semiconductor chip; X c is the shortest distance between the outer edge of the chip and the center of the chip (See FIG. 1 ); CTE encapsulant is the coefficient of thermal expansion of the encapsulant; and p is the Poisson ratio for the encapsulant. In preferred embodiments, the encapsulant is elastomeric, has a modulus of 0.5 to 600 MPa. and is comprised of a silicone gel, a silicone elastomer, a filled silicone elastomer, a urethane, an epoxy, or a flexiblized epoxy. In particularly preferred embodiments, the elastomeric encapsulant is comprised of a silicone elastomer. A plurality of leads 4 interconnect contacts on the semiconductor chip 2 to terminals on the dielectric element 5 . Leads 4 may be formed by any method, including the methods disclosed in commonly assigned U.S. Pat. Nos. 5,390,844; 5,398,863; 5,489,749; 5,491,302; and 5,536,909, the disclosures of which are incorporated herein by reference. Leads 4 may also be formed by wire bonding. In preferred embodiments, the leads are comprised of gold, copper or alloys thereof or combinations thereof. The leads 4 are used to electrically interconnect terminals on the dielectric element to contacts on the semiconductor chip or to electrically interconnect the terminals to an external circuit. The apertures 6 may be used to provide access for a bonding tool to the leads so that such electrically interconnections can be made. The apertures are optional and may be replaced with other means for making such electrical interconnections. One such means is an electrically conductive path disposed within such dielectric element. In another embodiment of the present invention, and as depicted in FIG. 2, compliant layer 11 may include a plurality of compliant spacers 11 a . One or more such compliant spacers 11 a may also be disposed between second surface 21 of expander ring 7 and the peripheral region of top surface 18 of dielectric element 5 . Compliant spacers 11 a preferably have a modulus of 0.5 to 600 MPa. In preferred embodiments, the compliant spacers 11 a are comprised of a silicone gel, a silicone elastomer or a flexiblized epoxy. In particularly preferred embodiments, the compliant spacers are comprised of a silicone elastomer. In order to dissipate heat from the assembly, a thermal spreader 10 may be connected to back surface 16 of semiconductor chip 2 with a first adhesive 9 , as depicted in FIG. 3 . Thermal spreader 10 may also be connected to the first surface 20 of expander ring 7 with a second adhesive or ring adhesive 26 . The second adhesive may also be used to accommodate for differences and tolerances between the semiconductor chip and the expander ring. First adhesive 9 and second adhesive 26 may be comprised of the same or different materials. In preferred embodiments, the first and second adhesives have a modulus between 0.5 to 600 MPa. The first and second adhesives are preferably comprised of a silicone gel, a silicone elastomer, a polyimide siloxane, or a flexiblized epoxy. The first and second adhesives may further comprise one or more fillers. In preferred embodiments, at least one of such fillers has a high thermal conductivity. Such highly thermally conductive fillers may be metallic or non-metallic. In preferred embodiments the second adhesive is comprised of a silicone elastomer. For semiconductor chip packages that will be used in low power applications, the preferred first adhesive is selected from the group consisting of filled flexiblized epoxies and filled silicone elastomers. Filled flexiblized epoxies are particularly preferred. For semiconductor chip packages which will be used in medium power applications, the preferred first adhesive is selected from the group consisting of filled flexiblized epoxies, filled polyimide siloxanes and filled silicone elastomers. For semiconductor chip packages which will be used in high power applications, the preferred first adhesive is an epoxy filled with silver/glass, an epoxy filled with gold/geranium alloys, or an epoxy filled with gold/silicon alloys. In an alternative embodiment, and as depicted in FIG. 4, a plurality of compliant spacers 11 b may be disposed between thermal spreader 10 and the first surface 20 of expander ring 7 . In preferred embodiments, the compliant spacers 11 b are comprised of a silicone gel, a silicone elastomer or a flexiblized epoxy. In particularly preferred embodiments, the compliant spacers are comprised of a silicone elastomer. In preferred embodiments and as depicted in FIG. 5, semiconductor chip 2 is connected to dielectric element 5 with a compliant layer comprised of compliant spacers 11 a . Expander ring 7 is connected to the peripheral region of the top surface 18 of dielectric element 5 with a plurality of compliant spacers 11 a and to thermal spreader 10 with a plurality of compliant spacers 11 b . Compliant spacers 11 a and 11 b may have similar dimensions or, as depicted in FIG. 5, different dimensions. Compliant spacers 11 a and 11 b may be comprised of the same or different materials. As depicted in FIG. 6, terminals 23 on the dielectric element 5 may be disposed on the top surface 18 of the dielectric element 5 . Leads 4 connect contacts (not shown) on semiconductor chip 2 with terminals 23 . A plated via 24 disposed in dielectric element 5 is connected to each terminal 23 . An electrically conductive mass 13 is disposed within each via 24 . In preferred embodiments each electrically conductive mass 13 is a solder ball. As depicted in FIG. 7, the semiconductor chip assembly 1 of the present invention may have both fan-in leads 4 a and fan-out leads 4 b . Dielectric element 5 has apertures 6 which accommodate both fan-in leads 4 a and fan-out leads 4 b . In preferred embodiments the fan-in and fan-out leads are arranged interstitially such that every other lead in a row of leads is a fan-in lead and the remaining leads are fan-out leads. Assembly 1 also has a solder mask or coverlay 14 . Coverlay 14 is disposed over the bottom surface 19 of dielectric element 5 . Coverlay 14 has a plurality of holes 25 which are aligned with terminals 23 . Assembly 1 further comprises a plurality of electrically conductive masses 13 which are disposed in such holes 25 . Masses 13 can be used to electrically and physically connect the assembly to an external circuit, such as a printed circuit board. The dielectric element described with reference to the above semiconductor chip packages and methods for making the same preferably is a flexible dielectric element. In particularly preferred embodiments, the dielectric element is a thin sheet of a polymeric material such as a polyimide, a fluoropolymer, a thermoplastic polymer, or an elastomer, with polyimide being a particularly preferred material for use as the flexible dielectric element. In preferred embodiments, the flexible dielectric element is from 10 to 100 microns and more preferably from 25 to 75 microns thick. Each expander ring is used to support the solder balls which are attached to the terminals of the fan-out leads and to add structural stability to the package. The strip of expander rings may be made of any material which will support the solder balls. The expander rings may be made a conductive or a non-conductive material. The expander rings may be made of a metal, a plastic, or a paper based material. In preferred embodiments, the expander rings are comprised of a material selected from alloy 42, copper, invar, steel, polypropylene, epoxy or paper phenolic, or alloys thereof, or combinations thereof. In particularly preferred embodiments, the expander rings are comprised of a material selected from copper, copper alloys, steel and combinations thereof. The expander ring may be thicker or thinner than the associated semiconductor chip. In preferred embodiments however, the thickness of the expander ring is less than or equal to the thickness of the semiconductor die. The CTE of the expander ring is preferably intermediate between the CTE of the semiconductor chip and the CTE of the dielectric element. If the package contains a thermal spreader, the CTE of the thermal spreader is preferably low, close to the CTE of the semiconductor chip, and the CTE of the expander ring is preferably intermediate between the CTE of the thermal spreader and the CTE of the dielectric: element. In preferred embodiments, the CTE of the thermal spreader is from 5 to 30 ppm/° C., inclusive. One or more capacitors, transistors, and/or resistors may be embedded in the expander ring and/or on the dielectric element and electrically connected, via wire bonds, solder or a conductive adhesive, to one or more terminals on the dielectric element. The thermal spreader is made from a material having a high thermal conductivity. In preferred embodiments, the CTE of the thermal spreader is close to the CTE of the semiconductor chip. For semiconductor chip packages which will be used in low power applications, the thermal spreader is preferably made from a material selected from the group consisting of copper, copper alloys, nickel plated copper alloys, aluminum, aluminum alloys, anodized aluminum alloys, and steel. For semiconductor chip packages which will be used in medium power applications, the thermal spreader is preferably made from a material selected from the group consisting of copper, copper alloys, alloy 42 and multi-layered laminates containing copper coated invar. The preferred multi-layer laminate is copper-invar-copper. For semiconductor chip packages which will be used in high power applications, the thermal spreader is preferably made of a material selected from the group consisting of aluminum nitride and tungsten copper. The coverlay may be a temporary coverlay or a permanent coverlay. The coverlay material must be capable of being bonded, at least temporarily, to the dielectric element and of sealing any apertures or holes in such element. The coverlay is preferably½ mil to 10 mils thick, more preferably ½ mil to 5 mils thick, most preferably less than 2.5 mils thick. The coverlay material is preferably comprised of polypropylene, polyester, polyimide or combinations thereof, with polyimide being particularly preferred for use as a permanent coverlay and polypropylene being particularly preferred for applications using a temporary coverlay. Materials which are commonly used as solder masks, such as solder masks sold under Dupont's brand name Pyralux® may also be used as a coverlay. Dupont's Pyralux® solder mask are generally photoimageable, dry film solder masks which are based on acrylic, urethane and -imide based materials. The coverlay may also comprise an adhesive layer. The adhesive layer is preferably comprised of an acrylic, epoxy or silicone adhesive, with acrylic adhesives being particularly preferred. Prior to the step in which the coverlay is laminated to the dielectric element, the adhesive layer must be tacky or must be in a form that is heat and/or pressure activated. In preferred embodiments, the coverlay used in the present invention is a permanent coverlay. The coverlay may have a plurality of apertures. If the coverlay is comprised of a photoimageable material, the apertures may be formed in the coverlay after it is attached to the dielectric element. The semiconductor chip package of the present invention can be made according to the method of the present invention. FIGS. 8A-8S depict various steps in one method of the present invention. As depicted in FIG. 8A, a dielectric element 101 is provided. In preferred embodiments, dielectric element 101 is flexible. Dielectric element 101 is in a strip form and has a top surface 102 , a bottom surface (not shown) opposite top surface 102 , and a plurality of apertures 104 . Apertures 104 are sometimes also referred to as bond windows. The flexible dielectric element described with reference to the above semiconductor chip packages and methods for making the same is preferably a thin sheet of a polymeric material such as a polyimide, a fluoropolymer, a thermoplastic polymer, or an elastomer, with polyimide being a particularly preferred material for use as the flexible dielectric element. In preferred embodiments, the flexible dielectric element is from 10 to 100 microns and more preferably from 25 to 75 microns thick. Polyimide in strip form is generally supplied with a plurality of sprocket holes 105 . Although such sprocket holes may be used as an alignment aid in the method of the present invention, such sprocket holes are not required to practice the present method. Flexible dielectric element 101 has a plurality of electrically conductive traces 106 . Only a portion of each trace is visible through the bond windows 104 . Each trace 106 has a contact end and a terminal-end. The contact-end will eventually be connected to a contact on the face surface of semiconductor chip 108 . Neither the tip nor the terminal-ends are visible in FIG. 8 A. Traces 106 may be disposed on either the top surface 102 or the bottom surface 103 of the flexible dielectric element 101 . In the embodiment pictured in FIGS. 8A-8S, traces 106 are disposed on the bottom surface 103 (See FIG. 8 H). As depicted in FIG. 8B, a plurality of compliant spacers 107 are disposed on the top surface 102 of flexible dielectric element 101 . Some methods of disposing such compliant spacers or resilient elements are described in commonly assigned U.S. Pat. No. 5,659,952 and U.S. patent application with Ser. No. 08/879,922 and a filing date of Jun. 20, 1997, the disclosures of which are incorporated herein by reference. In preferred embodiments, the compliant spacers 107 are comprised of a silicone gel, a silicone elastomer or a flexiblized epoxy. The compliant spacers preferably have a modulus of 0.5 to 600 MPa. In particularly preferred embodiments, the compliant spacers are comprised of a silicone elastomer. Prior to die attach some or all of the compliant spacers 107 may be in an uncured, partially cured or fully cured state. An adhesive may be disposed on the top surface of such spacers 107 . Commonly assigned U.S. patent application with Ser. No. 08/931,680 and a filing date of Sep. 16, 1997, the disclosure of which is incorporated herein by reference, teaches one method of disposing an adhesive over a compliant spacer or compliant pad. As depicted in FIG. 8C, a plurality of semiconductor chips 108 are then disposed over the top surface 102 of flexible dielectric element 101 . Each chip 108 has a face surface (not shown), a back surface 111 opposite the face surface, and a plurality of electrically conductive contacts (not shown) disposed on the face surface 110 . Each chip 108 is positioned over one set of bond windows 104 and the face surface of each is adhered to flexible dielectric element 101 . If compliant spacers 107 are in an uncured state, a partially cured state, or have an adhesive disposed on the top surfaces of such spacers, chips 108 may be adhered to flexible dielectric element 101 using such spacers 107 . Heat and pressure may be required to achieve a good bond between spacers 107 and chips 108 . As depicted in FIG. 8D, a strip of expander rings 109 is provided. Each expander ring 109 has a first surface 112 , a second surface (not shown) opposite first surface 112 , and four inner side walls 113 which define a central opening 114 . Each expander ring is used to support the solder balls which are attached to the terminals of the fan-out leads and to add structural stability to the package. Various methods of packaging semiconductor chips using expander rings are described in co-pending, commonly assigned U.S. patent application Ser. No. 09/067,310, having a filing date of Apr. 28, 1998, the disclosure of which is hereby w incorporated herein by reference. The expander rings of the '310 application are referred to as unitary support structures. The strip of expander rings 109 may be made of any material which will support the solder balls. The expander rings may be made of a conductive or a non-conductive material. The expander rings may be made of a metal, a plastic, or a paper based material. In preferred embodiments, the expander rings are comprised of a material selected from alloy 42, copper, invar, steel, polypropylene, epoxy or paper phenolic, or alloys thereof, or combinations thereof. In particularly preferred embodiments, the expander rings are comprised of a material selected from copper, copper alloys, steel and combinations thereof. The expander ring may be thicker or thinner than the associated semiconductor chip. In preferred embodiments however, the thickness of the expander ring is less than or equal to the thickness of the semiconductor die. The CTE of the expander ring is preferably intermediate between the CTE of the semiconductor chip and the CTE of the flexible dielectric element. If the package contains a thermal spreader, the CTE of the thermal spreader is preferably low, close to the CTE of the semiconductor chip, and the CTE of the expander ring is preferably intermediate between the CTE of the thermal spreader and the CTE of the flexible dielectric element. One or more capacitors, resistors, and/or transistors, may be embedded in the expander ring and electrically connected, via wire bonds, solder or a conductive adhesive, to one or more terminals on the flexible dielectric element. As depicted in FIG. 8E, the strip of expander rings 109 is disposed over the flexible dielectric element 101 such that a) the second surface of each expander ring 109 confronts the top surface 102 of the flexible dielectric element 101 ; b) the central opening 114 of each expander ring 109 is disposed around one of the semiconductor chips 108 ; and c) for each semiconductor chip 108 , a gap 115 is maintained between each inner side wall 113 and the outer perimeter of the semiconductor chip 108 . In preferred embodiments, W≧{(CTE expander ring −CTE chip )X c }/{CTE encapsulant (1+2p)}; where w is the width of gap 115 ; CTE expander ring is the coefficient of thermal expansion of the expander ring; CTE chip is the coefficient of thermal expansion of the semiconductor chip; X c is the shortest distance between the outer edge of the chip and the center of the chip; CTE encapsulant is the coefficient of thermal expansion of the encapsulant; and p is the Poisson ratio for the encapsulant which will be disposed within the gap. With some chips, such as, for example rectangular chips, Xc is not constant for all points on the outer edge of the chip. For such chips, w can be calculated for each point on the outer edge of the chip. The gap between the chip and the expander ring, as measured at each such point on the outer edge of the chip should be at least the value of w calculated for that point. In preferred embodiment however, the width of the gap is constant and is selected to be at least as wide as the highest value of w calculated for the chip. In preferred embodiments, the encapsulant is elastomeric. In more preferred embodiments, the elastomeric encapsulant has a modulus of 0.5 to 600 MPa. and is comprised oF a silicone gel, a silicone elastomer, a filled silicone elastomer, a urethane, an epoxy, or a flexiblized epoxy. In particularly preferred embodiments, the elastomeric encapsulant is comprised of a silicone elastomer. The strip of expander rings 109 may have one or more fidicuals to aid in the proper alignment of the expander rings on the flexible dielectric element. The sprocket holes 105 may also be used to aid in the alignment of the expander rings. The second surface of each of the expander rings 109 is adhered to the compliant spacers 107 , preferably using heat and/or pressure. In preferred embodiments, the first surface 112 of each expander ring 109 is coplanar with the back surface 111 of each semiconductor chip 108 . The second surface of the expander ring may be coplanar with the face surface of each semiconductor chip 108 . Such heat and pressure can also be used to correct for any lack of coplanarity between each expander ring 109 and the associated semiconductor chip 108 . As depicted in FIG. 8F, a strip of thermal spreaders 116 is provided. The strip of thermal spreaders 116 has an alpha surface (not shown) and a beta surface 117 opposite the alpha surface. The thermal spreader is made from a material having a high thermal conductivity. In preferred embodiments, the CTE of the thermal spreader is close to the CTE of the semiconductor chip. For semiconductor chip packages which will be used in low power applications, the thermal spreader is preferably made from a material selected from the group consisting of copper, copper alloys, nickel plated copper alloys, aluminum, aluminum alloys, anodized aluminum alloys, and steel. For semiconductor chip packages which will be used in medium power applications, the thermal spreader is preferably made from a material selected from the group consisting of copper, copper alloys, alloy 42 and multi-layered laminates containing copper coated invar. The preferred multi-layer laminate is copper-invar-copper. For semiconductor chip packages which will be used in high power applications, the thermal spreader is preferably made of a material selected from the group consisting of aluminum nitride and tungsten copper. The strip of thermal spreaders 116 may have a plurality of elongated slots 119 . Such slots 119 are incorporated in the strip of thermal spreaders 116 to ease the singulation process in which the strip of packaged semiconductor chips are cut into individual packages. The strip of thermal spreaders 116 may have one or more fiducials to aid in the alignment of the thermal spreaders. The strip of thermal spreaders may be aligned with sprocket holes 105 in flexible dielectric element 101 to aid in the positioning of the thermal spreaders. A first adhesive 118 is disposed on the beta surface 117 . Such adhesive may take for example, the form of a pad, a film or a dispensed pattern such as a plurality of dots of adhesive. Adhesive 118 will eventually be used to bond beta surface 117 to the back surfaces of each of semiconductor chips 108 . A second adhesive or ring adhesive 118 ′ may also be disposed on beta surface 117 and be in the form of a pad, a film or a plurality of dots. Second adhesive 118 may be used to accommodate for differences and tolerances between the semiconductor chip and the expander ring. The dots of adhesive 118 ′ will eventually be used to bond beta surface 117 to first surface 112 of each expander ring 109 . If the CTE of the strip of thermal spreaders 116 and the CTE of the semiconductor chips is not matched, then adhesive 118 should be compliant. In preferred embodiments, both adhesives 118 and 118 ′ are compliant. Adhesives 118 and 118 ′ may be comprised of the same or different materials. In preferred embodiments, the first and second adhesives are comprised of a silicone gel, a silicone elastomer, a polyimide siloxane, or a flexiblized epoxy. The first and second adhesive may further comprises one or more fillers. In preferred embodiments, at least one of such fillers has a high thermal conductivity. Such highly thermally conductive fillers may be metallic or non-metallic. In preferred embodiments, the first and second adhesives have a modulus between 0.5 to 600 MPa. and are comprised of a silicone gel, a silicone elastomer, a polyimide siloxane, or a flexiblized epoxy. In particularly preferred embodiments the second adhesive is comprised of a silicone elastomer. For semiconductor chip packages which will be used in low power applications, the preferred first adhesive is selected from the group consisting of filled flexiblized epoxies and filled silicone elastomers. Filled flexiblized epoxies are particularly preferred. For semiconductor chip packages which will be used in medium power applications, the preferred first adhesive is selected from the group consisting of filled flexiblized epoxies, filled polyimide siloxanes and filled silicone elastomers. For semiconductor chip packages which will be used in high power applications, the preferred first adhesive is an epoxy filled with silver/glass, an epoxy filled with gold/geranium alloys, or an epoxy filled with gold/silicon alloys. The dimensions of the dots of adhesives 118 and 118 ′ may be the same or different. The strip of thermal spreaders 116 is disposed over semiconductor chips 108 and expander rings 109 such that the beta surface 117 of the strip of thermal spreaders 116 confronts the back surfaces 111 of semiconductor chips 108 and the first surfaces 112 of each expander ring 109 . The strip of thermal spreaders 116 is adhered to such back surfaces and first surfaces with the adhesives 118 and 118 ′. Once this is complete, the alpha surface 120 of the strip of expander rings 109 is visible from a top plan view, as depicted in FIG. 8 G. FIG. 8H is a view of the bottom surface 103 of the flexible dielectric element 101 prior to the processing step in which the leads are formed. A portion of the face surface 110 of each chip 108 is visible in FIG. 8 H through bond windows 104 . FIG. 8H also depicts a plurality of electrically conductive traces 121 disposed on the bottom surface 103 of flexible dielectric element 101 . FIG. 8I is an exploded view of a portion of FIG. 8H, depicting more details of traces 121 . Each trace 121 has a terminal 122 and a contact-end 123 . Some of the traces 121 have a terminal 122 that is disposed on a portion of flexible dielectric element 101 which lies underneath the face surface 110 of semiconductor chip 108 . The directional descriptor “underneath”, as used to describe FIG. 8H (which is a bottom plan view), should be read to mean “below when viewed from a top plan view” and not with reference to any gravitational frame of reference. Some traces will eventually be formed into “fan-in” leads. Some of the traces (such as trace 121 ′) have a terminal 122 ′ that is disposed on a portion of the flexible dielectric element which lies underneath the second surface of expander ring 109 . Such traces 121 ′ will eventually be formed into “fan-out” leads. The package depicted in FIG. 8I has a total of 26 traces. In preferred embodiments, the package will have 40 or more leads, more preferably 40 to 1000 leads. In preferred embodiments, terminals 122 and 122 ′ are disposed in ordered rows or an area array having a consistent pitch. In preferred embodiments, the fan-in and fan-out leads are comprised of gold, copper or alloys thereof or combinations thereof. FIG. 8J depicts the flexible dielectric element 101 and the plurality of chips 108 after the fan-in and fan-out leads have been formed. FIG. 8K is an exploded view of a portion of FIG. 8 J. As depicted in FIG. 8K, the contact-end 123 of each trace 121 is bonded to an electrically conductive contact on the face surface 110 of semiconductor chip 108 to form a fan-in lead 124 which electrically interconnects the chip 108 to the flexible dielectric element 101 . The contact-end 123 ′ of each trace 121 ′ is bonded to an electrically conductive contact on the face surface 110 of semiconductor chip 108 to form a fan-out lead 124 ′. The fan-in and fan-out leads may be formed by any method, including the methods disclosed in commonly assigned U.S. Pat. Nos. 5,390,844; 5,398,863; 5,489,749; 5,491,302; and 5,536,909, the disclosures of which are incorporated herein by reference. In an alternative embodiment, the fan-in and fan-out leads may be formed by wire bonding each contact to the respective terminal. Next, the bond windows 104 and any other apertures or holes in flexible dielectric element 101 are sealed using a coverlay, such as coverlay 125 which is depicted in FIG. 8 L. The coverlay may be a temporary coverlay or a permanent coverlay. The coverlay material must be capable of being bonded, at least temporarily, to the flexible dielectric element and of sealing any apertures or holes in such element. The coverlay is preferably ½ mil to 10 mils thick, more preferably ½ mil to 5 mils thick, most preferably less than 2.5 mils thick. The coverlay material is preferably comprised of polypropylene, polyester, polyimide or combinations thereof, with polyimide being particularly preferred for use as a permanent coverlay and polypropylene being particularly preferred for applications using a temporary coverlay. Materials which are commonly used as solder masks, such as solder masks sold under Dupont's brand name Pyralux® may also be used as a coverlay. Dupont's Pyralux® solder masks are generally photoimageable, dry film solder mask which are based on acrylic, urethane and -imide based materials. The coverlay may also comprise an adhesive layer. The adhesive layer is preferably comprised of an acrylic, epoxy or silicone adhesive, with acrylic adhesives being particularly preferred. Prior to the step in which the coverlay is laminated to the flexible dielectric element, the adhesive layer must be tacky or must be in an activatable form, such as a heat and/or pressure activated from. In preferred embodiments, the coverlay used in the present invention is a permanent coverlay. The coverlay may have a plurality of apertures. If the coverlay is comprised of a photoimageable material, the apertures may be formed in the coverlay after it is attached to the flexible dielectric element. The coverlay depicted in FIG. 8L is photoimageable and has been exposed in a pattern corresponding to the pattern of terminals on the flexible dielectric element. As depicted in FIG. 8M, coverlay 125 is laminated to the bottom surface 103 of flexible dielectric element 101 . The coverlay may be vacuum laminated, pressure laminated, vacuum-pressure laminated or otherwise laminated onto the bottom surface 103 of the flexible dielectric element 101 . FIG. 8M depicts the bottom surface 103 after a transparent coverlay 125 has been laminated to it. A protective film 127 is provided, as depicted in FIG. 8 N. The protective film of the present invention can be any of the materials listed above for the coverlay. In preferred embodiments, however, the protective film used in the present invention is a temporary coverlay which is removed after use. The protective film may be removed by, for example, using heat, peeling the film from the strip of thermal spreaders, or immersing the protective film in a caustic solution. Protective film 127 is used to seal the elongated slots and any other apertures in thermal spreader 116 while a liquid composition is injected into the assembly to encapsulated it. Protective film 127 should be capable of being bonded to the alpha surface of thermal spreader 116 . Since protective film 127 may be removed after the encapsulation process, in preferred embodiments, protective film 127 forms only a temporary bond to the alpha surface of the strip of thermal spreaders 116 . As depicted in FIG. 8O, film 127 is adhered to the thermal spreader 116 to seal the elongated slots 119 . After coverlay 125 has been laminated to flexible dielectric element 101 and after protective film 127 has been adhered to the alpha surface of the strip of thermal spreaders 116 , the assembly can be encapsulated using a liquid composition which is curable to an encapsulant In preferred embodiments the encapsulant is elastomeric. The elastomeric encapsulant increases the reliability of the assembly by compensating for the mismatch in CTE between the semiconductor chip package and an external circuit. The liquid composition is disposed between the top surface 102 of the flexible dielectric element 101 and the thermal spreader 116 . The liquid composition fills the open spaces between any of the expander ring, the thermal spreader, the semiconductor chip, the flexible dielectric element, the compliant adhesive, and the compliant spacers. The liquid composition also fills in gap 115 (see FIG. 8E) between the expander ring 109 and the semiconductor chip 108 . The assembly may be encapsulated with the liquid composition via a dispensing operation, a dispensing operation followed by subjecting the assembly to vacuum and or pressure, a dispensing operation preformed while the assembly is under vacuum, or by a pressurized injection operation. Various methods of encapsulating the assembly are disclosed, for example, in commonly assigned U.S. patent application Ser. No. 09/067,698 filed on Apr. 28, 1998. FIG. 8P depicts the assembly of the present invention after the strip has been vacuum impregnated with liquid composition 126 . Terminals 122 and 122 ′ and a portion of each lead 124 and 124 ′ are visible in FIG. 8 P. The coverlay 125 seals against the bottom surface 103 of the flexible dielectric element 101 to prevent the liquid encapsulant 126 from contaminating terminals 122 and 122 ′. After being impregnated into the assembly, liquid composition 126 is cured or at least partially cured. Protective film 127 may then removed from thermal spreader 116 . Holes are formed in coverlay 125 by exposing the photimageable coverlay to a developer, such as potassium carbonate. The holes are formed in a pattern corresponding to the pattern of terminals 122 and 122 ′ on flexible dielectric element 101 . Flux is then applied on the terminals and, as depicted in FIG. 8Q, solder balls 128 are disposed within the holes in coverlay 125 . The solder balls are reflowed. The plurality of semiconductor chips 108 are then singulated as depicted in FIG. 8 R and FIG. 8S to form a plurality of packaged semiconductor chip assemblies 129 . The method described with reference to FIGS. 8A-8S employs various process steps which are conducted on components in strip format. The method of the present invention may also be practiced with components that are supplied in a reel to reel format.

A method of making a semiconductor chip assembly, including providing a dielectric element with a plurality of electrically conductive terminals, disposing an expander ring over the dielectric element so that a semiconductor chip on the dielectric layer is disposed in a central opening in the expander ring, and disposing an encapsulant in the gap between the expander ring and the semiconductor chip. The size of the gap is controlled to minimize the pressure exerted on the leads by the elastomer as it expands and contracts in response to changes in temperature. The semiconductor chip and expander ring may also be connected to a heat sink or thermal spreader with a compliant adhesive.

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a thermal analyzer, and more particularly, to heat insulation structure inside a furnace of a thermal analyzer. [0003] 2. Description of the Related Art [0004] As an example of the thermal analyzer, a differential scanning calorimeter (hereinafter, referred to as DSC) is a thermal analyzer that changes temperature of a furnace provided inside the apparatus according to a constant temperature rate program, to thereby measure a difference in temperature between a sample and a reference substance placed inside the furnace (heat flux type, which is one type of DSCs), or a difference in thermal energy, which is applied so as to eliminate the difference in temperature between the sample and the reference substance (power compensation type, which is another type of DSCs). [0005] In order that the DSC stably detect the difference in temperature between the sample and the reference substance or the difference in thermal energy necessary to maintain the difference in temperature therebetween to zero, it is important that a detector and a furnace portion having the detector mounted thereon are provided in a stable environment in which no direct influence of temperature disturbance is imposed. Further, from a viewpoint of providing a measurer with the convenience of being able to conduct a measurement in a wide temperature range, in order to realize a wide measurement temperature range from a desired high temperature to a temperature lower than room temperature (for example, −150° C. to 750° C.), it is also important that heat exchange between the furnace portion and the outside is suppressed to perform heating and cooling efficiently. [0006] For the reasons described above, general DSCs are designed so that the detector and the furnace portion having the detector mounted thereon are isolated from the external environment and insulated from heat. [0007] For example, there is proposed a heat flux DSC structured so that the entire furnace is covered with a partition wall and is further covered with a heat insulation case in which a heat insulation material is loaded into a space between an outer frame and an inner frame. The heat insulation case has an effect of suppressing influence of external temperature disturbance to provide a stable baseline, resulting in a high-sensitivity DSC measurement (see Japanese Patent Application Laid-open No. 2005-345333). [0008] Further, for example, the power compensation DSC is structured so that temperature control can be performed both on a furnace provided with a heater for applying thermal energy to a sample and a reference substance and on a thermal shield arranged outside the furnace. By controlling temperature of the thermal shield, that is, by controlling the surrounding environment of the furnace, a stable baseline can be obtained (see Japanese Patent Translation Publication No. 2008-530560). [0009] In the DSC measurement, sensitivity, resolution, and a noise level serve as performance indicators. In addition, baseline reproducibility is an important indicator. The “reproducibility” herein refers to “consistency of measurement baselines in repetition, which are obtained through repetitive measurements using the same temperature program”. [0010] In a case of low (poor) baseline reproducibility, even through the repetitive measurements using the same temperature program, the baseline changes from measurement to measurement, which raises difficulty in comparing measurement results. In a case of high (good) baseline reproducibility, on the other hand, results are easy to compare between measurements, with the result that more detailed thermal changes of the sample can be captured and reliability of measurement results themselves is increased. [0011] One of important factors of influence on the baseline reproducibility is a temperature environment given around the furnace, as well as accuracy of temperature control for the furnace that houses a detection portion. Even in a case where accurate temperature control is performed on the furnace, if the temperature environment given around the furnace fluctuates from measurement to measurement, the fluctuation of the temperature environment inevitably influences the baseline reproducibility as a measurement-based fluctuation in baseline, particularly for the high-sensitivity DSC that measures temperature or thermal energy. [0012] However, in a thermal analyzer described in the embodiment of Japanese Patent Application Laid-open No. 2005-345333, a metal heat insulation shield and a heat insulation cover in which a heat insulation material is loaded are provided for the purpose of isolation and heat insulation of the furnace and its surroundings. In this embodiment, when repetitive measurements involving heating and cooling of the furnace are performed according to a constant temperature program, the heat insulation shield and the heat insulation cover, which are arranged around the furnace, are also heated and cooled due to the influence thereof, and temperature changes thereof occur with a delay having a fixed time constant. This is because the overall heat insulation structure around the furnace, including the heat insulation shield and the heat insulation cover, has low thermal conductivity for suppressing disturbance and a predetermined heat capacity due to the structure itself. For example, when the furnace control is switched from heating to cooling, the heat insulation material around the furnace is not so cooled as compared to the furnace itself, resulting in a delay in temperature drop. Therefore, actual temperature inside the furnace exhibits thermal hysteresis due to repetitive heating and cooling. [0013] Due to the thermal hysteresis of the heat insulation structure, the temperature environment around the furnace is changed in the repetitive measurements, and as a result, there arises a problem of fluctuation in baseline. [0014] In the case of the technology described in Japanese Patent Translation Publication No. 2008-530560, a thermal shield whose temperature can be controlled is provided around the furnace. It is considered that by controlling temperature of the thermal shield as appropriate, the measurement-based change of the temperature environment around the furnace does not become larger. In this case, however, it is necessary to control temperature of the thermal shield according to the state of the furnace, and hence there arises a problem of more complicated apparatus structure and control system as compared to the general case. Further, it is necessary to allocate cooling performance of a cooling device also to the thermal shield in addition to the furnace whose temperature is originally desired to be controlled, and hence the cooling rate, the lowest reachable temperature, and the like are limited as compared to the case where only the furnace is simply cooled. SUMMARY OF THE INVENTION [0015] The present invention has been made in order to solve the above-mentioned problems, and it is therefore an object of the present invention to provide a thermal analyzer which does not need any complicated control and structure, and is capable of a measurement with high baseline reproducibility. [0016] In order to achieve the above-mentioned object, in a thermal analyzer according to the present invention, the furnace in which a sample is received and its surroundings are covered with a wall member, and accordingly the furnace is isolated from the outside. The wall member has a multilayer structure of at least two layers, and a layer having a heat insulation effect is provided between the layers constituting the wall member. Further, the heat insulation layer is set as a gas layer, and there is used an interlayer material which does not have an excessively high heat capacity as compared to a gas. [0017] In the multilayer wall member around the furnace, a metal may be used, such as stainless steel, for the first layer as a material having heat resistance and corrosion resistance, and for the second and subsequent layers, a metal material having relatively high thermal conductivity and heat dissipation property may be used, such as aluminum or copper. Further, a gas such as air or nitrogen may be used for the interlayer of the wall member. This structure avoids using, around the furnace, a solid heat insulation material having a relatively high heat capacity as compared to a gas, and hence the heat capacity of the heat insulation structure around the furnace becomes relatively lower. Accordingly, when the measurement is repeated, the heat insulation structure around the furnace allows a relatively quick temperature change as compared to the structure using the solid heat insulation material, and hence the thermal hysteresis due to a delay in response tends to be reduced. Thus, the change of the temperature environment around the furnace is suppressed to a small value. Further, a gas which is not high in thermal conductivity is used for the interlayer of the multilayer wall member, which realizes sufficient heat insulation property and small influence of disturbance, resulting in a measurement with a wide temperature range. As a result, the thermal analyzer capable of obtaining a baseline exhibiting high reproducibility in the wide temperature range is realized. [0018] As described above, according to the present invention, the heat insulation structure around the furnace is not excessively high in heat capacity as compared to a gas, and hence there is produced an effect of reducing the thermal hysteresis of the heat insulation structure around the furnace, which occurs at the time of repetitive measurements. As a result, the change of the temperature environment around the furnace in the repetitive measurements is suppressed, with the result that data exhibiting stable and high baseline reproducibility can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS [0019] In the accompanying drawings: [0020] FIG. 1 is a structural diagram according to an embodiment of the present invention; [0021] FIG. 2 is a schematic diagram of structure of a multilayer wall according to the embodiment of the present invention; [0022] FIG. 3 is a schematic diagram of structure of a multilayer lid according to the embodiment of the present invention; [0023] FIG. 4 is a graph showing an example of DSC baseline reproducibility of an apparatus according to the embodiment of the present invention; and [0024] FIG. 5 is a graph showing an example of DSC baseline reproducibility in a conventional technology. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT [0025] Hereinbelow, referring to the drawings, a thermal analyzer according to the present invention is described by taking a DSC as an example. Note that, dimensions of components or the like are changed as appropriate as long as the ratio thereamong does not lead to any problem, in particular. [0026] FIG. 1 illustrates apparatus structure of the DSC according to an embodiment of the present invention. [0027] The DSC includes a furnace 1 , and the furnace 1 has a furnace lid 1 a removably arranged in its upper portion. Further, a heater coil 2 is wound around the furnace 1 so as to heat the furnace 1 . Although not illustrated, the furnace 1 has a cover attached therearound so that the heater coil 2 is not exposed. There are arranged, inside the furnace 1 , a sample holder 3 a for receiving a sample substance, a reference substance holder 3 b for receiving a reference substance and thermal resistance 3 C for becoming a heat flow path of those each holders and the furnace. Both the holders have thermocouples connected thereto, which constitute a differential heat flow detection portion 3 d for detecting a temperature difference between the holders. Thermocouple wires 8 extending from the heat flow detection portion 3 d are connected to a measurement circuit, and detected signals are recorded in the form of a DSC curve after being amplified. [0028] A cooling block 5 arranged below the furnace 1 is structured so that a cooling device can be connected thereto as necessary, and is connected to the furnace 1 through an intermediation of a heat resistant material 4 . When cooling the furnace 1 , the cooling block 5 is cooled to function as a heat sink. The cooling block 5 and its surroundings are sufficiently insulated from heat of an external environment by a heat insulation material, and the cooling block 5 is housed in a jacket case 7 , which prevents dewing or the like caused at the time of cooling. Embodiment [0029] Next, referring to the drawings, heat insulation structure around the furnace of the present invention is described. [0030] In FIG. 1 , the furnace 1 has a multilayer wall 9 arranged therearound. The multilayer wall 9 is formed of a plurality of layers (in this case, three layers) so as to cover the entire furnace 1 . In this case, the multilayer wall 9 has a cylindrical shape in which the cross section thereof has a round shape. [0031] FIG. 2 is a schematic diagram of the multilayer wall 9 alone. [0032] A first layer wall 9 a is formed of stainless steel as a material having heat resistance and corrosion resistance. The first layer wall 9 a has a thickness of 0.5 mm, and has a cylindrical shape in which the diameter thereof is set so that a gap between the first layer wall 9 a and the furnace 1 is 1 mm. The upper and lower portions of the cylinder each have an opening. [0033] A second layer wall 9 b and a third layer wall 9 c are each formed of aluminum as a material having relatively high thermal conductivity and heat dissipation property. The second layer wall 9 b and the third layer wall 9 c each have a thickness of 1 mm, and their diameters are each set so as to be 20 mm larger than the inner layer diameter. The second layer wall 9 b and the third layer wall 9 c are each fixed to the jacket case 7 of the apparatus body so that a distance of the interlayer becomes 10 mm. The layers are heat-separated so that heat transfer due to solid conduction between the layers becomes as small as possible. In order to increase the heat separation property, there is employed, for the interlayer, a gas having relatively lower thermal conductivity as compared to the solid thermal conduction (in this case, air having atmospheric pressure). The multilayer wall 9 described above is combined with a multilayer lid 10 described later to provide a multilayer structure 11 , with the result that the flow of the air within the space is restricted between the layers and the air functions as a heat insulation layer. As described above, the multilayer structure 11 including the gas layer has heat insulation property against the external environment, with the result that the furnace can be isolated from the external environment and therefore insulated from heat. [0034] In fixing the layer walls to the jacket case 7 , the layer walls are bonded to the jacket case 7 so that the space between the layers is sealed with high reliability. [0035] In this embodiment, the thickness of the wall member is set to 1 mm, but the optimal thickness varies depending on the thermal conductivity of the material. In a case of a metal wall member, the thickness preferably ranges from 0.1 mm to 3 mm, and more preferably, from 0.3 mm to 2 mm, approximately. [0036] In this embodiment, the distance of the interlayer is set to 10 mm, but from the above-mentioned viewpoint of solid thermal conduction and heat insulation, the range of the distance of the interlayer preferably ranges from 0.5 mm to 50 mm, and more preferably, from 1.0 mm to 30 mm. When the distance of the interlayer is 0.5 mm or less, the thermal conduction becomes highly effective. When the distance of the interlayer is 50 mm or more, the layer walls less contribute to the heat insulation property and in the case where a gas is loaded into the interlayer, influence of convection thereof becomes larger, with the result that the stability of the baseline is likely to be lost. When the number of layers or the distance of the interlayer is decreased, the heat insulation property tends to be decreased, whereas when the number of layers or the distance of the interlayer is increased, the heat insulation property tends to be increased. The number of layers is not limited to three as long as the layers have heat insulation property necessary for the apparatus. For example, a multilayer formed of two, four, or more layers may be employed, and two to five layers are preferred. This is because a single layer cannot form the above-mentioned heat insulation layer and hence is hard to obtain the heat insulation property necessary for the apparatus, whereas too many layers less contribute to improvement in heat insulation effect necessary for the apparatus and result in larger outline dimension of the apparatus and lower cost effectiveness. [0037] The material used for the interlayer only needs to be a substance which does not have an excessively high heat capacity as compared to the gas but has a heat capacity substantially equal to that of the gas. Thus, the material is not limited to the air as in the above description using the gas, and may be a material formed of an interlayer substance that produces the effect of the present invention. [0038] Note that, this embodiment has described that the multilayer wall 9 has its cross section in a round shape, but the present invention is not limited thereto and the cross section may have a polygonal shape. [0039] FIG. 3 is a structural diagram of the multilayer lid 10 . The multilayer lid 10 is formed of the same number of layers (in this case, three) as the cylindrical wall member. In order that the layers of the multilayer lid 10 have the same structure as the cylindrical metal wall member 9 , a first layer lid 10 a is formed of stainless steel as a material having heat resistance and corrosion resistance, and is a disk having a thickness of 0.5 mm, while a second layer lid 10 b and a third layer lid 10 c are each formed of aluminum as a material having relatively high thermal conductivity and heat dissipation property, and are each a disk having a thickness of 1 mm. The layer lids 10 a , 10 b , and 10 c constituting the multilayer lid 10 are integrated by a shaft 10 d , which is inserted into a through-hole provided at the center. With the shaft 10 d , the lids may be removed through a single removal operation, which saves labor and time for sample replacement and the like as compared to a case of separate lids of layers. Note that, in order to suppress the thermal conduction, a stainless steel material having relatively low thermal conductivity is used for the shaft 10 d , and the diameter thereof is as small as 1 mm. [0040] FIG. 4 is a graph showing an example of DSC baseline reproducibility obtained in a case where the multilayer structure 11 according to the present invention is arranged around the furnace and is used for heat insulation. FIG. 5 is a graph showing an example of DSC baseline reproducibility obtained in a conventional case where the heat insulation material is used around the furnace. [0041] FIGS. 4 and 5 each show an example of a case where temperature is raised at a constant rate, with the axis of ordinate representing a heat flow difference and the axis of abscissa representing temperature. In the case of the structure in which the heat insulation material is used around the furnace as in the conventional technology, as illustrated in FIG. 5 , DSC baselines obtained through repetitive measurements (first to third temperature rise baselines in the repetitive measurements) exhibit a large divergence and hence the reproducibility is low. [0042] In the case where the multilayer structure 11 according to the present invention is arranged around the furnace and is used for heat insulation, on the other hand, as illustrated in FIG. 4 , DSC baselines obtained through repetitive measurements (first to third temperature rise baselines in the repetitive measurements) exhibit quite a smaller divergence and hence the reproducibility is high. [0043] As described above, this embodiment has described the case where the present invention is applied to the DSC, but the applicable range of the present invention is not limited thereto. For example, the present invention is also applicable to a thermogravimetry (TG) or a differential thermal analysis (DTA).

To improve measurement accuracy by eliminating influence of a change of a temperature environment around a furnace of a thermal analyzer, the thermal analyzer includes a multilayer structure of at least two sealed layers for covering the furnace and its surroundings so as to isolate the furnace and its surroundings from an outside. An interlayer of the multilayer structure is loaded with a substance having a heat capacity equal to the heat capacity of a gas inside the furnace.

This application is a continuation of U.S. patent application Ser. No. 08/192,570, filed Feb. 7, 1994, now U.S. Pat. No. 5,685,815, issued Nov. 11, 1997, and a division of U.S. patent application Ser. No. 08/428,288, filed Apr. 25, 1995, now U.S. Pat. No. 5,879,814, both of which are incorporated herein in their entirety by reference. This invention relates to paper containing alkaline sizing agents for paper that have a reactive functional group that covalently bonds to cellulose fiber and hydrophobic tails that are oriented away from the fiber, and processes for using the paper. BACKGROUND OF THE INVENTION The amount of fine paper produced under alkaline conditions has been increasing rapidly, encouraged by cost savings, the ability to use precipitated calcium carbonate (PCC), an increased demand for improved paper permanence and brightness, and an increased tendency to close the wet-end of the paper machine. Current applications for fine paper require particular attention to sizing before conversion or end-use, such as high-speed photocopies, envelopes, forms bond including computer printer paper, and adding machine paper. The most common sizing agents for fine paper made under alkaline conditions are alkenyl succinic anhydride (ASA) and alkyl ketene dimer (AKD). Both types of sizing agents have a reactive functional group that covalently bonds to cellulose fiber and hydrophobic tails that are oriented away from the fiber. The nature and orientation of these hydrophobic tails cause the fiber to repel water. Commercial AKD's, containing one β-lactone ring, are prepared by the dimerization of the alkyl ketenes made from two saturated, straight-chain fatty acid chlorides; the most widely used being prepared from palmitic and/or stearic acid. Other ketene dimers, such as the alkenyl based ketene dimer (Aquapel 421 of Hercules Incorporated), have also been used commercially. Ketene multimers, containing more than one such β-lactone ring, have been described in Japanese Kokai 168992/89, the disclosure of which is incorporated herein by reference. ASA-based sizing agents may be prepared by the reaction of maleic anhydride with an olefin (C 14 -C 18 ). Although ASA and AKD sizing agents are commercially successful, they have disadvantages. Both types of sizing agents, particularly the AKD type, have been associated with handling problems in the typical high-speed conversion operations required for the current uses of fine paper made under alkaline conditions (referred to as alkaline fine paper). The problems include reduced operating speed in forms presses and other converting machines, double feeds or jams in high-speed copiers, and paper-welding and registration errors on printing and envelope-folding equipment that operates at high speeds. These problems are not normally associated with fine paper produced under acid conditions (acid fine paper). The types of filler and filler addition levels used to make alkaline fine paper differ significantly from those used to make acid fine paper, and can cause differences in paper properties such as stiffness and coefficient of friction which affect paper handling. Alum addition levels in alkaline fine paper, which contribute to sheet conductivity and dissipation of static, also differ significantly from those used in acid fine paper. This is important because the electrical properties of paper affect its handling performance. Sodium chloride is often added to the surface of alkaline fine paper to improve its performance in end use. The typical problems encountered with the conversion and end-use handling of alkaline fine paper involve: 1. Paper properties related to composition of the furnish; 2. Paper properties developed during paper formation; and 3. Problems related to sizing. The paper properties affected by paper making under alkaline conditions that can affect converting and end-use performance include: Curl Variation In Coefficient Of Friction Moisture Content Moisture Profile Stiffness Dimensional Stability MD/CD Strength Ratios One such problem has been identified and measured as described in "Improving The Performance Of Alkaline Fine Paper On The IBM 3800 Laser Printer," TAPPI Paper Makers Conference Proceedings (1991), the disclosure of which is incorporated herein by reference. The problem occurs when using an IBM 3800 high speed continuous forms laser printer that does not have special modifications intended to facilitate handling of alkaline fine paper. That commercially-significant laser printer therefore can serve as an effective testing device for defining the convertibility of various types of sized paper on state-of-the-art converting equipment and its subsequent end-use performance. In particular, the phenomenon of "billowing" gives a measurable indication of the extent of slippage on the IBM 3800 printer between the undriven roll beyond the fuser and the driven roll above the stacker. Such billowing involves a divergence of the paper path from the straight line between the rolls, which is two inches above the base plate, causing registration errors and dropped folds in the stacker. The rate of billowing during steady-state running time is measured as the billowing height in inches above the straight paper path after 600 seconds of running time and multiplied by 10,000. Typical alkaline AKD sized fine paper using a size furnish of 2.2 lbs. per ton of paper shows an unacceptable rate-of-billowing, typically of the order of 20 to 80. Paper handling rates on other high-speed converting machinery, such as a Hamilton-Stevens continuous forms press or a Winkler & Dunnebier CH envelope folder, also provide numerical measures of convertiblity. There is a need for alkaline fine paper that provides improved handling performance in typical converting and reprographic operations. At the same time, the levels of sizing development need to be comparable to that obtained with the current furnish levels of AKD or ASA for alkaline fine paper. SUMMARY OF THE INVENTION The invention comprises paper made under alkaline conditions and treated with a 2-oxetanone-based sizing agent (herein referred to as 2-oxetanone sizing agent), that at 35° C. or at 25° C. or even at 20° C., is not a solid (not substantially crystalline, semi-crystalline, or waxy solid; i.e., it flows on heating without heat of fusion). More preferably, the sizing agent according to the invention is a liquid at 35° C., or at 25° C., or even at 20° C. (The references to "liquid" of course apply to the sizing agent per se and not to an emulsion or other combination.) The paper according to the invention does not encounter significant machine-feed problems on high speed converting machines and reprographic operations. Such problems are defined as significant in any specific conversion or reprographic application if they cause misfeeds, poor registration, or jams to a commercially unacceptable degree as will be discussed below, or cause machine speed to be reduced. The preferred structure of 2-oxetanone sizing agents is as follows: ##STR1## in which n can be 0 to 6, more preferably 0 to 3, and most preferably 0, and R and R", which may be the same or different, are selected from the group of straight or branched alkyl or alkenyl chains, provided that not all are straight alkyl chains and preferably at least 25% by weight of the sizing agent consists of the 2-oxetanone structure in which at least one of R and R" is not straight chain alkyl. R and R" are substantially hydrophobic in nature, are acyclic, and are at least 6-carbon atoms in length. When n>0 the materials are termed 2-oxetanone multimers. R' is preferably straight chain alkyl, more preferably C 2 -C 12 straight chain alkyl, most preferably C 4 -C 8 straight chain alkyl. Preferably the invention further comprises alkaline paper that is treated with the 2-oxetanone based sizing agent according to the invention and contains a water soluble inorganic salt of an alkali metal, preferably NaCl, as well as alum and precipitated calcium carbonate (PCC). However, the paper of this invention will often be made without NaCl. The paper of this invention is generally sized at a size addition rate of at least 0.5, preferably at least about 1.5, and most preferably at least 2.2 pounds/ton or higher. It may be, for instance, continuous forms bond paper, adding machine paper, or envelope-making paper, as well as the converted products, such as copy paper and envelopes. Also, the invention preferably comprises paper that is made under alkaline papermaking conditions and sized with a 2-oxetanone-based sizing agent having irregularities in the chemical structure of its pendant hydrophobic constituents; i.e., the said chemical structure contains irregularities such as carbon-to-carbon double bonds or branching in one or more of the hydrocarbon chains. (Conventional AKD'S are regular in that they have saturated straight-chain hydrocarbon chains). Preferably according to the invention, paper that is made under alkaline papermaking conditions is sized with a sizing agent containing the 2-oxetanone functionality. Preferably the 2-oxetanone sizing agent is made from a fatty acid selected from the group consisting of oleic, linoleic, linolenic or palmitoleic fatty acid chlorides, or a mixture of them. More preferably, the 2-oxetanone sizing agent made from a fatty acid selected from the said group is at least 25% of the sizing agent, more preferably at least about 50% and most preferably at least about 70%. Also preferably each pendant hydrocarbon chain has 6 to 22 carbon atoms, most preferably 10 to 22 carbon atoms. Preferably the paper according to the invention is capable of performing effectively in tests that measure its convertibility on state-of-the-art converting equipment and its performance on high speed end-use machinery. In particular, the paper according to the invention, that can be made into a roll of continuous forms bond paper having a basis weight of from about 30 to 60 lbs./3000 ft 2 , more specifically about 40 to 50 lbs./3000 ft 2 , and that is sized at an addition rate of at least about 2.2 pounds/ton, is capable of running on the IBM Model 3800 high speed, continuous-forms laser printer without causing a rate of billowing in inches of increase per second ×10,000 greater than about 5. Further, the preferred paper according to the invention, that can be made into sheets of 81/2×11 inch reprographic cut paper having a basis weight of about 15-24 lbs./1300 ft 2 and is sized at an addition rate of at least about 2.2 pounds/ton, is capable of running on a high speed laser printer or copier without causing misfeeds or jams at a rate of 5 or less in 10,000. The preferred paper according to the invention, having a basis weight of about 15-24 lbs./1300 ft 2 , also can be converted to a standard perforated continuous form on the Hamilton-Stevens continuous form press at a press speed of at least about 1775 feet per minute. The invention is directed to a process of using fine paper made under alkaline conditions and sized with a 2-oxetanone sizing agent that is not solid at 35° C. in high speed precision converting or reprographic operations. It is also directed to a process of using fine paper made under alkaline conditions and sized with a 2-oxetanone sizing agent that has irregularities in the chemical structure of one or more of its hydrocarbon chains in high speed precision converting or reprographic operations. The invention also comprises the process of converting the paper according to the invention to a standard perforated continuous form on a continuous forms press at a press speed of from about 1300 to 2000 feet per minute. A further process according to the invention comprises running 81/2×11 inch reprographic cut paper, having a basis weight of about 15-24 lbs./1300 ft 2 , on a high speed, continuous laser printer or copier without causing misfeeds or jams at a rate of 5 or less in 10,000, preferably without causing misfeeds or jams at a rate of 1 or less in 10,000. By comparison, paper sized with standard AKD had a much higher rate of double feeds on the IBM 3825 high speed copier (14 double feeds in 14,250 sheets). In conventional copy-machine operation, 10 double feeds in 10,000 sheets is unacceptable. A machine manufacturer considers 1 double feed in 10,000 sheets to be unacceptable. Another process according to the invention comprises converting the paper according to the invention into at least about 900 envelopes per minute, preferably at least about 1000 per minute. DETAILED DESCRIPTION OF THE INVENTION Alkaline sizing agents, that give levels of sizing comparable to those obtained with current AKD and ASA sizing technology, and improved handling performance in typical end-use and converting operations, have a reactive 2-oxetanone group and pendant hydrophobic hydrocarbon tails. In that respect, they resemble traditional AKD-based sizing agents, but unlike the saturated straight chains in the fatty acids used to prepare conventional solid alkyl ketene dimer based sizing agents, the hydrocarbon chain in one or both of the fatty acid chlorides used to prepare this class of sizing agents contain irregularities in the chemical structure of the pendant hydrocarbon chains, such as carbon-to-carbon double bonds and chain branching. Due to the irregularities in the pendant hydrocarbon chains, these sizing agents are not solid, and preferably are liquid, at or near room temperature. Examples of this class of sizing agents are 2-oxetanone based materials prepared from oleic acid, and 2-oxetanone based materials prepared from either Pamak-1 or Pamolyn 380 liquid fatty acid (fatty acid mixtures available from Hercules Incorporated and consisting primarily of oleic and linoleic acid. Other examples of fatty acids that may be used are the following unsaturated fatty acids: dodecenoic, tetradecenoic (myristoleic), hexadecenoic (palmitoleic), octadecadienoic (linolelaidic), octadecatrienoic (linolenic), eicosenoic (gadoleic), eicosatetraenoic (arachidonic), docosenoic (erucic), docosenoic (brassidic), and docosapentaenoic (clupanodonic) acids. 2-oxetanone multimers formed from mixtures of these fatty acids and a dicarboxylic acid are also examples, including: 2-oxetanone multimers prepared from a 2.5:1 mixture of oleic acid and sebacic acid, and 2-oxetanone multimers prepared from a 2.5:1 mixture of Pamak-1 fatty acid and azelaic acid. Preferred examples are 2-oxetanone multimers with fatty acid to diacid ratios ranging from 1:1 to 3.5:1. These reactive sizing agents are disclosed as being prepared using methods known from Japanese Kokai 168992/89, the disclosure of which is incorporated herein by reference. In the first step, acid chlorides from a mixture of fatty acid and dicarboxylic acid are formed, using phosphorous trichloride or another conventional chlorination agent. The acid chlorides are then dehydrochlorinated in the presence of triethylamine or another suitable base, to form the multimer mixture. Stable emulsions of these sizing agents can be prepared in the same way as standard AKD emulsions. The sizing agents of this invention may be used for internally or externally sizing paper. Experimental Procedures Paper for evaluation on the IBM 3800 was prepared on the pilot paper machine at Western Michigan University. To make a typical forms bond paper-making stock, the pulp furnish (three parts Southern hardwood kraft pulp and one part Southern softwood kraft pulp) was refined to 425 ml Canadian Standard Freeness (C.S.F.) using a double disk refiner. Prior to the addition of the filler to the pulp furnish (10% medium particle-size precipitated calcium carbonate), the pH (7.8-8.0), alkalinity (150-200 p.p.m.), and hardness (100 p.p.m.) of the paper making stock were adjusted using the appropriate amounts of NaHCO 3 , NaOH, and CaCl 2 . The 2-oxetanone sizing agents, including the multimers, were prepared by methods used conventionally to prepare commercial AKD's; i.e, acid chlorides from a mixture of fatty acid and dicarboxylic acid are formed, using a conventional chlorination agent, and the acid chlorides are dehydrochlorinated in the presence of a suitable base. The 2-oxetanone sizing agent emulsions, including the multimer emulsions, were prepared according to the disclosure of U.S. Pat. No. 4,317,756, which is incorporated herein by reference, with particular reference to Example 5 of the patent. Wet-end additions of sizing agent, quaternary-amine-substituted cationic starch (0.75%), alum (0.2%), and retention aid (0.025%) were made. Stock temperature at the headbox and white water tray was controlled at 110° F. The wet presses were set at 40 p.s.i. gauge. A dryer profile that gave 1-2% moisture at the size press and 4-6% moisture at the reel was used (77 f.p.m.). Before the size press, the sizing level was measured on a sample of paper torn from the edge of the sheet, using the Hercules Size Test (HST). With Hercules Test Ink #2, the reflectance was 80%. Approximately 35 lb/ton of an oxidized corn starch and 1 lb/ton of NaCl were added at the size press (130° F., pH 8). Calender pressure and reel moisture were adjusted to obtain a Sheffield smoothness of 150 flow units at the reel (Column #2, felt side up). A 35 minute roll of paper from each paper making condition was collected and converted on a commercial forms press to two boxes of standard 81/2"×11" forms. Samples were also collected before and after each 35 minute roll for natural aged size testing, basis weight (46 #/3000 ft 2 ), and smoothness testing. The converted paper was allowed to equilibrate in the printer room for at least one day prior to evaluation. Each box of paper allowed a 10-14 minute (220 f.p.m.) evaluation on the IBM 3800. All samples were tested in duplicate. A standard acid fine paper was run for at least two minutes between each evaluation to reestablish initial machine conditions. The height of billowing in inches at the end of the run, and the rate at which billowing occurred (inches of increase in billowing per second), were used to measure the effectiveness of each approach. EXAMPLE 1 A number of sizing agents were tested for their effects on the IBM 3800 runnability of a difficult-to-convert grade of alkaline fine paper. The above Experimental Procedures were followed. The rate of paper billowing on an IBM 3800 high speed printer was used to evaluate the converting performance of each sample of paper. A summary of the results of this testing is given in Table 1. Several 2-oxetanone based alkaline sizing agents are shown that give a better balance of sizing and runnability on the IBM 3800 (for instance, less billowing at similar levels of sizing) than a standard AKD sizing agent made for comparative purposes. The standard AKD sizing agent was made from a mixture of stearic and palmitic acids. This is a standard sizing agent of the type that lacks any irregularities, such as double bonds or branching, in its pendant hydrocarbon chains. The best balance of sizing and handling performance was obtained with one of the following agents: a 2-oxetanone based sizing material made from a mixture of about 73% oleic acid, about 8% linoleic acid, and about 7% palmitoleic acid, the remainder being a mixture of saturated and unsaturated fatty acids, available from Henkel-Emery under the name Emersol NF (referred to herein for convenience along with similar sizes based on oleic acid as an oleic acid size). Another 2-oxetanone size prepared from Pamolyn 380 fatty acid, consisting primarily of oleic and linoleic acid and available from Hercules Incorporated, and a 2-oxetanone sizing agent made from isostearic acid. All these sizing agents were liquids at 25° C., and in particular, at equal sizing levels, gave better converting performance on the IBM 3800 than the control made from a mixture of stearic and palmitic acids. TABLE 1______________________________________Composition Addition Natural Rate of of Size Level Aged HST Billowing*______________________________________Oleic Acid 1.5 122 1.6 " 2.2 212 15.1 " 3.0 265 29.4 " 4.0 331 55.5 Oleic Acid 2.2 62 1.6 (Pamolyn 380) Isostearic 2.2 176 1.5 Control 1.5 162 23.8 " 2.2 320 55.0______________________________________ *Inches of billowing/sec. × 10,000. EXAMPLE 2 Additional sizing agents were tested for their effects on IBM 3800 paper runnability in a second set of experiments. The above Experimental Procedures were followed. An AKD emulsion and an alkenyl succinic anhydride (ASA) emulsion were evaluated as controls. The ASA emulsion was prepared as described by Farley and Wasser in "The Sizing of Paper (Second Edition)," "Sizing with Alkenyl Succinic Anhydride" page 51, (1989). The performance parameters measured in these studies were natural aged sizing and runnability on the IBM 3800. A summary of the results of these evaluations is given in Table 2. The materials tested gave a better balance of sizing and converting performance (less billowing at the same level of sizing) than either of the commercial ASA or AKD sizing agents used as controls. The best balance of sizing and handling performance was obtained with: a 2-oxetanone size prepared from Pamak-1 fatty acid (a mixture comprised primarily of oleic and linoleic acid) and a 2-oxetanone multimer prepared from a 2.5:1 mixture of oleic acid and sebacic acid. Both sizing agents gave levels of sizing comparable to that obtained with the ASA and AKD controls. Both sizing agents gave paper with better runnability on the IBM 3800 than the paper sized with either the ASA or AKD standards. TABLE 2______________________________________Composition Addition Natural Rate of of Size Rate Aged HST Billowing______________________________________Oleic/ 1.5 34 <1.7 Linoleic " 2.2 203 <1.7 " 3.0 193 <4.6 " 4.0 250 <17.5 Oleic/ 1.5 53 <10.4 Sebacic " 2.2 178 <1.7 " 3.0 270 <3.4 " 4.0 315 16.6 Control 1.5 162 166 (AKD) " 2.2 320 48 Control 1.5 127 52 (ASA) " 2.2 236 83 " 3.0 286 166______________________________________ EXAMPLE 3 Two 2-oxetanone multimers prepared from mixtures of azelaic acid and oleic acid, and mixtures of azelaic acid and oleic/linoleic fatty acid, were tested. Paper for testing was prepare on the pilot paper machine using the conditions described in the Experimental Procedures. A standard paper sized with a commercial AKD size dispersion was evaluated as a control. A summary of the results of these evaluations is given in Table 3. Both types of 2-oxetanone multimer gave levels of HST sizing similar to those obtained with the standard AKD control. Both multimer sizes gave lower levels of billowing on the IBM 3800 than the control. TABLE 3______________________________________Composition Addition Natural Rate of of Size Level Aged HST Billowing______________________________________Oleic/ 2.2 186 <1.2 Azeleic 2.5:1 " 3 301 <2.2 " 4 347 <2.3 Oleic/ 2.2 160 <2.4 Linoleic: Azeleic 2.5:1 " 3 254 <2.4 " 4 287 <2.4 Control 2.2 267 10 " 3 359 23______________________________________ EXAMPLE 4 A series of Pamak-1 fatty acid:azelaic acid 2-oxetanone multimers with fatty acid to dicarboxylic acid ratios ranging from 1.5:1 to 3.5:1 were evaluated in a fourth set of experiments. Paper for testing was again prepared on the pilot paper machine at Western Michigan University using the conditions described in Example 1. The performance parameters measured in these studies were: natural aged sizing efficiency (acid ink) and runnability on the IBM 3800. Standard AKD and ASA sized paper were evaluated as controls. A summary of the results of these evaluations is given in Table 4. All of the Pamak-1:azelaic acid 2-oxetanone multimers gave a better balance of sizing and IBM 3800 runnability than either of the commercial controls. TABLE 4______________________________________Composition Addition Natural Rate of of Size Level Aged HST Billowing______________________________________1.5:1 2.5 209 <5 " 4.5 339 <5 2.5:1 2.0 214 <5 " 3.5 312 <5 " 4.0 303 <5 3.5:1 2.5 312 <5 " 4.0 303 <5 Control 1.5 255 <5 (AKD) " 3.0 359 15 Control 3.0 253 23 (ASA)______________________________________ EXAMPLE 5 An evaluation of a 2-oxetanone size made from oleic acid, with a comparison to a AKD commercial size made from a mixture of palmitic and stearic acids, was carried out on a high speed commercial fine paper machine (3000 f.p.m., 20 tons of paper produced per hour, 15 lb/1300 ft 2 ). A typical forms bond paper making stock similar to that used in Example 1 was used. Addition levels of the two sizing agents were adjusted to give comparable levels of HST sizing (20-30 seconds, 85% reflectance, Hercules Test Ink #2). No deposits were observed on the paper machine. The paper produced under these conditions was then evaluated on a high speed Hamilton continuous forms press. The Hamilton press converts paper to a standard perforated continuous form. Press speed was used as a measure of performance. Two samples of the AKD control were tested before and after the evaluation of the paper sized with the oleic acid based size. The results are shown in Table 5. The paper sized with the oleic acid size clearly converted at a significantly higher press speed than the paper sized with the AKD control. TABLE 5______________________________________ Hamilton Run # Sizing Agent Press Speed______________________________________1 AKD CONTROL 1740 f.p.m. 2 AKD CONTROL 1740 f.p.m. 3 OLEIC ACID 1800 f.p.m. 2-OXETANONE 4 OLEIC ACID 1775 f.p.m. 2-OXETANONE 5 AKD CONTROL 1730 f.p.m. 6 AKD CONTROL 1725 f.p.m.______________________________________ EXAMPLE 6 An evaluation of oleic acid 2-oxetanone size, with a comparison with an AKD commercial standard size prepared from a mixture of palmitic and stearic acid, was carried out on a commercial paper machine producing a xerographic grade of paper (3100 f.p.m., 42 lb/3000 ft 2 ). As in Example 5, addition levels of each sizing agent were adjusted to give comparable levels of HST sizing after natural aging (100-200 seconds of HST sizing, 80% reflectance, Hercules Test Ink #2). No deposits were observed on the paper machine. The paper produced with oleic acid 2-oxetanone size ran without any jams or double feeds on a high speed IBM 3825 sheet fed copier (no double feeds in 14,250 sheets). Paper prepared with the AKD controls had a much higher rate of double feeds on the IBM 3825 (14 double feeds in 14,250 sheets). EXAMPLE 7 A 2-oxetanone size was prepared from oleic acid by known methods. A sizing emulsion was then prepared from the oleic acid-based size by known methods. Copy paper sized with the oleic acid-based sizing emulsion was made on a commercial fine paper machine (3100 f.p.m., 40 tons of paper produced per hour, 20 lb/1300 ft 2 , 10% precipitated calcium carbonate, 1 lb of sodium chloride/ton of paper added at the size press). Copy paper sized with a standard AKD (prepared from a mixture of palmitic acid and stearic acid) sizing emulsion was also made as a control. The addition level of each sizing agent was adjusted to give 50-100 seconds of HST sizing (1.4 lb of standard commercial AKD, 1.9-2.1 lb of oleic acid size per ton of paper, 80% reflectance, Hercules Test Ink #2). The copy paper sized with oleic acid size ran without any jams or double feeds on a high speed IBM 3825 sheet fed copier (no double feeds in 99,000 sheets). The paper sized with the AKD control had a much high rate of double feeds on the IBM 3825 (14 double feeds in 27,000 sheets). EXAMPLE 8 Two samples of 2-oxetanone-based sizing agents were prepared from oleic acid and Pamak-1 fatty acid (a mixture consisting primarily of linoleic and oleic acid) by known methods. Sizing emulsions were prepared from both sizes. Forms bond paper samples sized respectively with the Pamak-1 fatty acid-based size and the oleic acid-based size were made on a commercial fine paper machine (approximately 3000 f.p.m., 16 lb/1300 ft 2 , 5 lb/ton alum, 10 lb/ton quaternary amine substituted starch). Forms bond paper sized with a commercial AKD (prepared from a mixture of palmitic acid and stearic acid) sizing emulsion was also made as a control. The addition level of each sizing agent (See Table 6) was adjusted to give comparable levels of HST sizing at the reel (70% reflectance, Hercules Test Ink #2). The paper produced under these conditions was converted on a high speed Hamilton continuous forms press. The Hamilton press converts paper to a standard perforated continuous form. Press speed was used as a measure of paper performance. The results are listed in the following Table 6. Each press speed is an average of measurements made on six different rolls of paper. The paper sized with the oleic acid-based size and the paper sized with the Pamak-1 fatty acid-based size converted at a significantly higher press speed than the paper sized with the AKD control. TABLE 6______________________________________ Sizing Add'n HST Sizing Hamilton Run # Agent Level (seconds) Press Speed______________________________________1 AKD Control 2.0#/Ton 208 1857 f.p.m. 2 Oleic Acid-based 2.5#/Ton 183 1957 f.p.m. Size 3 PAMAK-1 Fatty 2.5#/Ton 185 1985 f.p.m. Acid-based Size______________________________________ EXAMPLE 9 A 2-oxetanone-based sizing agent was prepared from oleic acid by known methods. A sizing emulsion was then prepared from the oleic acid-based sizing agent by known methods. Envelope paper sized with the oleic acid-based sizing emulsion and containing 16% precipitated calcium carbonate was made on a commercial fine paper machine in two basis weights, 20 lb and 24 lb per 1300 ft 2 . Envelope paper sized with a standard commercial AKD (prepared from a mixture of palmitic acid and stearic acid) and a commercial surface sizing agent (0.5 lb/ton Graphsize A) sizing emulsion was also made as a control. The addition level of each internal sizing agent was adjusted to give comparable levels of HST sizing at the reel (100-150 seconds, 80% reflectance, Hercules Test Ink #2). The paper sized with each of the two sizing agents was converted to envelopes on a Winkler & Dunnebier CH envelope folder. The 20 lb paper was converted to "Church" envelopes. The 24 lb paper was converted to standard #10 envelopes. Envelope production rate (envelopes per minute) was used as a measure of paper converting performance. The results are listed in the following Table 7. The paper sized with the oleic acid-based size converted at a significantly higher speed than the paper sized with the AKD control. TABLE 7______________________________________ Size Envelopes Sizing Add'n HST Basis per Agent Level (sec.) Weight Product Minute______________________________________AKD 2.0#/Ton 100-150 20# Church 850 Control Envelope Oleic Acid- 2.9#/Ton 100-150 20# Church 900-950 based Size Envelope AKD 1.5#/Ton 100-150 24# #10 965 Control Envelope Oleic Acid- 2.5#/Ton 100-150 24# #10 1000-1015 based Size Envelope______________________________________

Fine paper that is sized with a 2-oxetanone alkaline sizing agent and that does not encounter machine feed problems in high speed converting or reprographic machines, including continuous forms bond paper and adding machine paper, processes for converting the paper into envelopes, continuous forms bond paper and adding machine paper, and paper products of the processes.

RELATED APPLICATIONS [0001] The present application claims the benefit of U.S. Provisional Application Serial No. 60/302,463, filed Jul. 2, 2001, which is incorporated herein by reference. GOVERNMENT RIGHTS [0002] The present invention was developed under United States Air Force Contract No. F33615-97-C-2778, and the United States Air Force has certain rights therein. BACKGROUND OF THE INVENTION [0003] The present invention relates generally to blade tracks for gas turbine engines. More specifically, the present invention relates to a blade track support assembly having controlled thermal expansion properties. [0004] A gas turbine engine is typical of the type of machinery which the invention described herein may be advantageously employed. It is well known that a gas turbine engine conventionally comprises a compressor for compressing inlet air to an increased pressure for combustion in a combustion chamber. A mixture of fuel and the increased pressure air is burned in the combustion chamber to generate a high temperature gaseous flow-stream for causing rotation of turbine blades within the engine. In an effort to reduce specific fuel consumption of engines, there has been a move to increase the efficiency of the turbine by decreasing the clearance between the rotating turbine blade tips and the stationary blade track. In designing a gas turbine engine with tighter blade tip clearances, designers must account for transient conditions that the gas turbine engine experiences during operation. During acceleration of the gas turbine engine, the rotor carrying the turbine blades experiences mechanical growth in a radial direction faster than blade track/shroud, thereby allowing the potential for mechanical contact between the blade tips and the blade track/shroud. During deceleration of the gas turbine engine, the blade track/shroud exhibits mechanical shrinkage in the radial direction more quickly than the rotor, thereby allowing the potential for mechanical contact between the blade tips and the blade track/shroud. [0005] The present invention seeks to control the clearance between the blade tips and the blade track/shroud by lowering the thermal expansion of the blade track support assembly, thereby allowing a reduction in the steady state run clearance between the blade tip and the blade track/shroud. The resulting improvement is manifested as an increase in turbine efficiency and a reduction in specific fuel consumption. The present invention provides a novel and non-obvious blade track/shroud assembly for a gas turbine engine. SUMMARY OF THE INVENTION [0006] One form of the present invention contemplates a support for a gas turbine engine blade track, comprising: a ring member having a centerline, the ring member having a cavity open towards the centerline; a plurality of circumferentially spaced ceramic members positioned within the cavity; and, a plurality of metallic members positioned within the cavity, the plurality of ceramic members and the plurality of metallic members are positioned so that each of the plurality of ceramic members is located between a pair of the plurality of metallic members. [0007] Another form of the present invention contemplates a low expansion blade track assembly, comprising: a continuous hoop member having an inner surface; a plurality of blade track segments coupled to the hoop member; and, expansion control means located within the hoop member for supporting the plurality of blade track segments, the expansion control means has a first surface abutting the inner surface. [0008] Yet another form of the present invention contemplates a blade track support assembly, comprising: a continuous metallic ring member symmetrical about a centerline, the ring member having a circumferential channel opening towards the centerline; a plurality of circumferentially spaced ceramic cylinders extending parallel to the centerline and located within the channel, each of the ceramic cylinders has an outer surface; and, a plurality of circumferentially spaced metallic spacers extending parallel to the centerline and located within the channel, each of the plurality of metallic spacers including a pair of bearing surfaces corresponding to the outer surface, each of the plurality of ceramic cylinders located between a pair of the plurality of metallic spacers, and each of the bearing surfaces abutting one of the ceramic cylinders. [0009] One object of the present invention is to provide a unique blade track support. [0010] Further objects and advantages of the present invention will become apparent from the following description of the preferred embodiment. BRIEF DESCRIPTION OF THE DRAWINGS [0011] [0011]FIG. 1 is a partially fragmented side elevational view of a gas turbine engine. [0012] [0012]FIG. 2 is a side view of a portion of one embodiment of a blade track and support assembly that comprises a portion of the FIG. 2 gas turbine engine. [0013] [0013]FIG. 3 is a view of the blade track and support assembly of FIG. 2 that has the gas turbine engine blade removed. [0014] [0014]FIG. 4 is an enlarged view of the blade track support assembly of FIG. 3 from the direction of arrow A with the blade track segments removed. [0015] [0015]FIG. 5 is an enlarged end view of the blade track support assembly of FIG. 3. [0016] [0016]FIG. 6 is an illustrative view of the spacers and low expansion members comprising a portion of the blade track support assembly of the present invention. FIG. 7 is an illustrative end view of the spacers and low expansion members being assembled into the blade track support assembly with the sidewall removed for clarity. FIG. 8 is a graph showing the reduction in tip clearance by lowering the thermal expansion coefficient of the blade track support assembly. DESCRIPTION OF THE PREFERRED EMBODIMENTS [0017] For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates. [0018] Referring to FIG. 1, there is shown an exemplary gas turbine engine 11 . It is understood that such power plants as gas turbine engine 11 may find application in all types of aircraft, including for example, helicopters, fixed wing planes, tactical fighters, trainers, missiles and other related apparatus. Further, the gas turbine engine may be equally suited to be used for a wide variety of industrial applications. Historically, there has been the widespread application of industrial gas turbine engines, such as pumping sets for gas and oil transmission lines, electricity generation and naval propulsion. The gas turbine engine 11 includes a compressor 12 , a combustor 13 and a turbine 14 . This is only an example of a gas turbine engine and it will be understood that there are a variety of ways that the components may be linked together or arranged. The gas turbine engine 11 includes a rotor disk 17 , with a plurality of turbine blades 16 mounted thereto, that is coupled to a shaft (not shown) within gas turbine engine 11 . [0019] With reference to FIG. 2, there is illustrated a portion of the working fluid sealing system 20 . In one form of the present invention, the sealing system 20 is designed to minimize the leakage of working fluid in the working fluid pathway in the turbine 14 . However, it is contemplated herein that the working fluid sealing system could be utilized in other portions of the working fluid pathway within the gas turbine engine. Controlling the clearance 28 between the tips 27 of turbine blades 26 and surface 25 of the blade track 24 assists in minimizing the bypassing of the rotor 17 and turbine blades 16 by the working fluid. The present application will utilize the term blade track interchangeably with the term shroud and/or air seal. [0020] In one form of the present invention, the sealing system 20 comprises two components that form a substantial seal between the rotating and static components. The term “seal” as utilized herein includes the reduction and/or the elimination of fluid flow between the rotating and static components. There is no intent herein to limit the term “seal” to a theoretical fluid tight seal. More specifically, the support structure for the stationary components comprises thermal expansion control features that are intended to control the movement of blade track inner surface 25 . In a preferred embodiment, support 22 comprises a continuous hoop member 30 and an inner cavity 34 . In one form the ring member that is symmetrical about a centerline X defines the continuous hoop member 30 . Inner cavity 34 is bounded by inner surface 38 of continuous hoop member 30 and first sidewall 32 and second sidewall 33 . However, other geometries for the ring member are contemplated herein. [0021] With reference to FIGS. 4 and 5, there is illustrated one embodiment of the first and second side walls 32 and 33 which may be substantially interrupted at various intervals by circular holes 50 and slots 52 extending from the holes to inner edge 53 of support 22 . It will be appreciated that slot 52 permits some movement of the adjacent walls to allow for expansion or contraction. Further, circular opening 50 permits material deformation that may accompany changes in the width of slot 52 to be spread over a greater area to limit stress concentrations. While the particular use of the combination of slots and circular openings are contemplated in a preferred embodiment, it will be appreciated that other side wall interruptions or configurations that allow for at least some expansion or contraction may be utilized with the present invention. In another form of the present invention, the sidewalls are continuous and have no interruption or slots cut therein. [0022] An expansion control material 36 is disposed within inner cavity 34 . Expansion control material 36 includes an outer surface 40 adapted to bear against inner surface 38 of continuous hoop 30 . As discussed more fully below, expansion control material 36 may be maintained in position by engagement with inner surface 38 under a compressive load. Further sidewalls 32 and 33 inhibit forward and backward movement. Still further, once assembled, blade track 24 includes a finger member 46 adapted to limit inward buckling of the expansion control material. It is understood herein that blade track preferably includes a plurality of blade track segments. The finger member in one embodiment extends continuous along the assembled blade track and in an alternate embodiment is discontinuous. [0023] In a preferred form of the invention, expansion control material 36 comprises multiple materials having different thermal expansion coefficients. Referring to FIGS. 2 and 6, there is illustrated a preferred form of the expansion control material 36 which comprises alternating ceramic members 64 and metallic spacers 60 . The ceramic members 64 and the metallic spacers 60 are preferably elongated in the direction of the centerline X. It is preferred that the ceramic members 64 have a rounded outer surface to minimize point loading and more preferably are cylindrical in shape. In FIG. 2, the ceramic members 64 are shown in phantom lines and the metallic spacers 60 are shown in solid lines. While the combination of ceramic and metallic spacers is shown in the preferred embodiment, other materials may be utilized in accordance with the present invention to tailor the blade track expansion characteristics. Additionally, it is desired that the ceramic members 64 have a low thermal expansion coefficient such that the inner diameter of the support member and attached blade track remains substantially constant in diameter, or with only minor variations, over a wide range of operating conditions for the gas turbine engine. Ceramic members 64 preferably have a thermal expansion coefficient lower than the thermal expansion coefficient of the hoop 30 and the spacers 60 . Further, the expansion control material may be selected to impart greater or lesser expansion forces on the support member to impart the desired blade tip clearances for various applications. [0024] The blade track assembly according to the present invention may be assembled in the following steps. The assembled fluid sealing system 20 has the ceramic members 64 disposed between metallic spacers 60 and loaded against the inner surface 38 within the cavity 34 of the hoop 30 . A blade track support member with a continuous hoop is provided. Ceramic cylinders 64 and metallic spacers 60 are fitted into position within interior cavity 34 to engage one another and put support ring 30 in tension by pressing against surface 38 . The cylinders 64 and spacers 60 would likewise be loaded in compression against the inner surface 38 of the hoop 30 . During assembly, it is contemplated the last cylinder would be pressed into position. With reference to FIG. 7, there is illustrated one form of the ceramic cylinders 64 and the metallic spacers being finally installed against the continuous hoop member 30 . The hoop member is heated to a predetermined temperature and the ceramic cylinders 64 and metallic spacers 60 are set into position. A load is applied to push the last ceramic cylinder 64 and metallic spacers 60 into position. The blade track segments 24 are then moved axially into position. In one form of the present invention the predetermined temperature is about 500° F. [0025] As previously mentioned, fingers 46 on the blade track would engage surface 41 on spacers 60 to inhibit the cylinder and spacer assembly forming the expansion control material from buckling inward. The blade tracks 24 are held in place by engagement of flange 42 on wall 33 with recess 44 on the blade track and corresponding structures formed on opposite wall 32 and blade track portion. As will be understood, the combination of metallic and ceramic components in the compression stack placed in the inner cavity 34 permits the expansion control material to be tailored to meet specific thermal expansion characteristics. [0026] A cylindrical shape for the ceramic cylinders 64 is preferred to decrease the average and peak stresses applied on the surface. Still more preferably, the metal spacers would be shaped and coated to decrease the bearing stresses in the parts. The spacers preferably include a curved portion 100 that corresponds to the shape of the outer surface of the ceramic members 64 . In one form of the present invention the metallic spacers are formed of MAR-M247 and the ceramic members are formed of silicon nitride. In another form of the present invention the metallic spacers are coated with a high temperature dry film lubricant. However, other materials and coatings are contemplated herein. As shown in FIG. 6 , it is contemplated that a slight gap 66 may be created between adjacent spacers 60 and 62 . The gap is preferably within a range of about 0.020 inches to about 0.060 inches. It will be understood that should ceramic cylinder 64 deteriorate, collapse, or otherwise fail, gap 66 may close and the system may continue to operate, at a slightly lower effectiveness. [0027] Referring to FIG. 8, there is illustrated a graph showing advantages that may be achieved with use of the present invention for controlling blade track expansion. Specifically, in the preferred embodiment illustrated and described herein, the effect on one application was to lower the thermal expansion coefficient of the support assembly from 9.0×10 −6 in/in/deg. F to 5.0×10 −6 in/in/deg. F. As shown in FIG. 7, the tip clearance required due to thermal transients can be reduced from 0.078 inches to 0.032 inches (a 60% reduction) for one application such as shown in FIG. 2. [0028] While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected. In reading the claims, it is intended that when words such as “a,” “an,” “at least one,” or “at least a portion” are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language “at least a portion” and/or “a portion” is used the item can include a portion and/or the entire item unless specifically stated to the contrary.

The clearances between an array of turbine blades and its surrounding blade track may be controlled by an expansion control material system supporting the blade tracks. The blade track support hoop is placed in tension by the expansion control material placed therein and the expansion control material is placed in compression.

PRIORITY This application claims priority to U.S. non-provisional Application Ser. No. 13/578,593 filed Mar. 11, 2013, which is the National Stage Entry of International Application PCT/US11/26287 with an International Filing Date of Feb. 25, 2011 which in turn claims priority to U.S. provisional application Ser. No. 61/310,133 filed Mar. 3, 2010, “Method of high throughput detection of small molecule effectors of particle interactions, as well as derivation of particle binding stoichiometry and equilibrium association constants.” BACKGROUND The high throughput detection of small molecule inhibitors and/or enhancers of particle interaction is desired in many fields of science. By “particle,” we refer to such objects as protein and polymer molecules together with their conjugates and co-polymers, viruses, bacteria, virus-like particles, liposomes, polystyrene latex emulsions, nanoparticles, and all such particles within the approximate size range of one to a few thousand nanometers. Dynamic light scattering provides an excellent analysis method for screening large chemical libraries, such as small molecule libraries of compounds, for effectors of particle interactions. Such libraries are typically available at molecular screening centers, such as the Scripps Research Institute Molecular Screening Center in Jupiter, Fla., the Broad Institute in Cambridge, Mass., the Molecular Screening Shared Resource centered at the University of California, Los Angeles, and others. Small molecule libraries of compounds may also be held by companies, private individuals, foundations, etc. Compound collections can exceed 300,000 molecules that possess diverse architecture and function. Depending on the particles used, the high throughput screening of chemical libraries can lead to a greater understanding of cellular function, the discovery of new drugs, or any variety of nanotechnology-related innovations. Additionally, libraries of macromolecules, such as a library of a proteins subjected to site directed mutagenesis at a large number of sites, may also be screened to identify which residue(s) modulate/change interactions with the binding partner(s). Additionally libraries of nanoparticles, such as gold particles or quantum dots, may also be screened against binding partners using this method. Alternatively, a nucleic acid fragment library could be screened against a protein to determine which region the protein may bind to. The aforementioned screen types could be done in the presence or absence of small molecule modulators. Any particle type can potentially be screened in this manner. The detection and characterization of reversible associations of particles in solution is also essential in many areas of science. For illustrative purposes, we shall focus specifically upon the interactions of protein molecules and their conjugates, though the techniques disclosed will be equally applicable to all the other particle types listed. Whenever the word “molecule” is used within this specification, it will be understood that the word “particle” may be substituted therefore in most cases without any limitations implied upon the inventive methods described. The study and measurement of molecular associations is important for many reasons; whether to gain understanding of cellular function or to develop and formulate pharmaceuticals or other biologically active materials. Essentially, most pharmaceuticals have functionality due solely to association with molecules within the body, so the discovery and accurate characterization of these associations is a key element for pharmaceutical development. Molecules of the same species may self-associate to form dimers, trimers, and higher order complexes, whereas molecules of different species may associate with each other to yield complexes of various compositions. More than two particle types may combine to form a complex. Such associations may be reversible or irreversible. For reversible associations, the binding affinities are characterized by a unique equilibrium constant. The equilibrium constant specifies the relative concentrations of the complex(s) and the component monomers for a given set of conditions. According to Le Châtlier's principle, every closed system must eventually reach equilibrium. When reactants in a reversible process are in excess of their equilibrium concentrations, the reaction proceeds to convert the reactants to products and achieve equilibrium. Alternately, when products are in excess, the reaction proceeds in a reverse direction to convert product to reactant and again achieve equilibrium. For the reaction of molecules A and B to form the complex AB, A+B AB, the equilibrium association constant is written: K a = [ AB ] [ A ] ⁡ [ B ] , where the bracketed terms correspond to the corresponding concentrations of the molecules A, B, and their complex AB. Although constant under stable conditions, the equilibrium constant of a given association may change in response to environmental factors, such as temperature, buffer salinity, or the presence of other factors modulating the interaction. There are many techniques used to measure equilibrium constants and characterize molecular associations. However, the majority can detect only tightly bound interactions, and require the tagging/labeling or immobilization of one of the binding partners. As any modification of the molecule can potentially influence the interaction, techniques implementing free-solution testing are optimal. “Free-solution” means that molecules are neither tagged/labeled nor immobilized for analysis. As no molecule-specific immobilization/tagging protocol is required, free solution techniques are not limited to a single molecular type, such as proteins. Free solution techniques are applicable to most molecular types. There are several well-established free-solution methods to determine stoichiometry and equilibrium constants, such as calorimetry and sedimentation equilibrium. Static light scattering is another option. The theory of using static light scattering measurements at different solution concentrations to determine self or hetero association constants has long been known, cf. Huglin, 1972 Light Scattering From Polymer Solutions , Academic Press, London and New York, by W. Burchard and J. M. G. Cowie in Section 17, Selected Topics in Biopolymeric Systems, as well as Hirs, 1973 , Methods in Enzymology Volume XXVII, Enzyme Structure, Part D , Academic Press, London and New York, by Pittz et al. in section 10, Light Scattering and Differential Refractometry. Such measurements were demonstrated fairly recently by T. Yamaguchi et al. in Biochem. Biophys. Res. Commun., 2002, Vol. 290, 1382-1387 and improved upon by Attri et al., in Anal. Biochem., 2005, Vol. 346, 132-138, where they termed the technique “concentration gradient light scattering”. In static light scattering, the intensity of scattered light is proportional to the molar mass of the molecule; a dimer scatters twice as much light as two monomers. For example, in the study of self-association, the static light scattering concentration gradient method measures the intensity of scattered light over a series of concentrations of the molecule studied. The scattered light changes for each concentration, in accordance with the change in the population of the associated species. The association constant quantifies how the associated species change at different concentration ratios. To determine the association constant and stoichiometry of the interaction, the experimental data are fit against models that estimate the concentrations of the individual components present at each solution concentration. The three free-solution methods, static light scattering, calorimetry, and sedimentation equilibrium, require a relatively large amount of sample when used in their standard configurations. Techniques requiring minimal sample quantities for measurement are often required, as the required molecules may not be available in sufficient quantities, as synthesis or isolation and purification can present significant challenge and expense. Finally, none of the three methods are suitable for high-throughput measurement. Thus, the low productivity characteristics of all three methods impede practical study spanning a large compositional range. Recently, a fourth free-solution method has been explored: back-scattering interferometry with high-throughput capability and very low sample requirements. Cf Bornhop et al. Science 317, pages 1732-1736 (2007). Unfortunately, this method is limited to systems that bind in a 1:1 ratio. Other stoichiometries, which commonly occur in nature, cannot be distinguished or characterized. The search for a free-solution, high-throughput method with low sample requirements and the ability to detect multiple binding stoichiometries remains. To date, no such method has been reported. Our inventive method, on the other hand, based on the use of dynamic light scattering resolves, thereby, the previously discussed problems. Dynamic light scattering is a well-established technique, typically used to determine the diffusion coefficients of scattering particles in solution and, from them, an associated set of hydrodynamic radii. The hydrodynamic radius is the radius of a hard sphere whose diffusion coefficient is the same as that measured for the sample particle. Dynamic light scattering, also known as quasi-elastic light scattering, or QELS, uses the measured fluctuations in the light scattered from a sample to determine these quantities. When in solution, sample particles are buffeted by the solvent molecules. This leads to a random motion of the particles called Brownian motion. As light scatters from the moving particles, this random motion imparts a randomness to the phase of the scattered light, such that when the scattered light from two or more particles is combined, a changing intensity of such scattered light due to interference effects will occur. The dynamic light scattering measurement of the time-dependent fluctuations in the scattered light is achieved by a fast photon counter. The fluctuations are directly related to the rate of diffusion of the particles through the solvent. The fluctuations are then analyzed to yield diffusion coefficients and, from these, the hydrodynamic radii of the sample. The time variations of the intensity fluctuations are quantified by means of so-called autocorrelation techniques. Depending upon the experimental configuration of the dynamic light scattering instrumentation, the resulting autocorrelation function may be an intensity-intensity or field-field autocorrelation function, or a combination of these two. The intensity-intensity correlation function is g ( 2 ) ⁡ ( τ ) = 〈 I ⁡ ( t ) ⁢ I ⁡ ( t + τ ) 〉 〈 I ⁡ ( t ) 〉 2 ( 1 ) where I(t) is the intensity of the scattered light at time t, and the brackets indicate averaging over all t. The correlation function depends on the delay τ, that is, how the intensity variation in time t+τ correlates to the intensity variation in t. FIG. 1 shows a typical correlation function for a sample of Immunoglobulin G protein in solution. In this figure open triangles are data, and the solid line is a fit of the data to a simple exponential function, described below. As described in various light scattering texts, cf. B. Chu, Laser Light Scattering: Basic Principles and Practice , (Academic Press, Boston, 1991), for a single particle freely diffusing in solution, the correlation function of Eq. 1 becomes g (2) (τ)= B +β exp(−2Γτ)  (2) where B is the baseline of the correlation function at infinite delay (τ→∞), β is the correlation function amplitude at zero delay (τ=0), and Γ is the decay rate. An algorithm is used to fit the measured correlation function to Eq. (2) to retrieve Γ. From this point, the diffusion coefficient for the particle, D, is calculated from Γ from the relation, D = Γ q 2 . Here, q is the magnitude of the scattering vector, i.e. q = 4 ⁢ π ⁢ ⁢ n 0 λ 0 ⁢ sin ⁡ ( θ / 2 ) , where n 0 is the solvent index of refraction, λ 0 is the vacuum wavelength of the incident light, and θ is the scattering angle. Finally, the hydrodynamic radius r h of an equivalent diffusing sphere is derived from the Stokes-Einstein equation, r h = k B ⁢ T 6 ⁢ π ⁢ ⁢ η ⁢ ⁢ D , where k B is the Boltzmann constant, T is the absolute temperature, and η is the solvent viscosity. Since it is relatively insensitive to stray background light from the walls of the containing structures, dynamic light scattering measurements may be made from very small sample volumes, thus reducing sample quantity requirements and enabling the use of high throughput measurements. As such, dynamic light scattering may be used with microtiter plate based systems or very small volume cuvettes, each such sample holding element containing only a few microliters of sample. Although such measurements require a higher concentration of sample relative to those needed for static light scattering measurements, the smaller sample volumes typically result in a significant overall reduction in total sample quantity required. The application of the static light scattering concentration gradient procedures to dynamic light scattering, DLS, would be a significant improvement for determining particle association stoichiometry and affinity, as this would permit far smaller sample quantities, as well as high throughput processing. For the static light scattering method, as each different sample composition is examined, an associated excess Rayleigh ratio is measured. Such Rayleigh ratios are related directly to the molecular species producing them. A dynamic light scattering measurement, on the other hand, yields a correlation function derived from the scattered light fluctuations attributed to these same molecular species. Such correlation functions may be decomposed, following certain assumptions, to represent the distributions, in terms of diffusion coefficients and their associated hydrodynamic radii, of the scattering molecules. Whereas static light scattering data are relatively easy to model in terms of postulated associated states, DLS responses to the presence of such states are far more complex. For example, the molar mass of a molecular homodimer scatters four times the amount of light as one of its two monomers, or twice as much light as scattered by the two separated monomers. On the other hand, the difference of the diffusion coefficient of a dimer from that of one of its composite monomers depends critically upon the structure of the associated dimer. Considering just the corresponding hydrodynamic radii as a measure of these differences, there may be a range of values, whereas for the static light scattering case there is a known discrete value. The application of dynamic light scattering, for obtaining molecular association constants and stoichiometries by modeling thereof a series of relative concentration gradients has been attempted infrequently over the past four decades, although DLS techniques are frequently used to study irreversible particle association, particularly particle aggregation. Examples of such prior work are described by Claes, et al. in Chapter 5, An on-line dynamic light scattering instrument for macromolecular characterization, of Laser Light Scattering in Biochemistry Eds. S. E. Harding, et. al., 1992, The Royal Society of Chemistry, Cambridge, UK, and Wilson Journal of Structural Biology 142, 56-65 (2003). Self association was studied by Mullen et al., J. Mol. Biol. 1996, 262, 746-755, MacColl et al., Biochemistry 1998, 37, 417-423, an Lunelli, Physical Review Letters 1993, 70(4), 513-516. In the dynamic light scattering industry, Protein Solutions developed a “Fraction Calculator” in an early version of the Dynamics software to determine the fraction of each species in a binary equilibrium, using the average r h and postulating or measuring the two end points. Malvern also has recently published an application note that proposes how the percent monomer in a monomer/dimer system can be estimated using the hydrodymic radius of the mixture. In terms of heteroassociations, Vannini et al., J. Biol. Chem., 2004, Vol. 279, Issue 23, 24291-24296, used dynamic light scattering to predict the stoichiometry of a protein complex by isolating the complex and estimating the molecular mass of the complex from the hydrodynamic radius. This study involved a complex that could be isolated from the component protein monomers, indicating the association was irreversible or very tightly bound. DLS measurements have also been performed at a series of two or more ratios of two components such as the work by Wang et al., Biopolymers, 1981, v.20, p 155-168, Murphy et al., Biophysical Journal, 1988, 54, 45-56, Leliveld S. R. et al., Nucleic Acids Research, 2003, Vol. 31, No. 16, 4805-4813, and Sharma et al., Biophysical Journal: Biophysical Letters, 2008, L71-L73. BRIEF DESCRIPTIONS OF THE DRAWINGS FIG. 1 shows an autocorrelation function derived from a solution of Immunoglobulin G protein. FIG. 2 compares two models used to estimate the hydrodynamic radius of associating species. FIG. 3 shows results obtained from protein heteroassociation experiments indicating binding and stoichiometry for chymotrypsin and soybean trypsin inhibitor. No binding is found in the presence of the inhibitor AEBSF. FIG. 4 shows results obtained from a protein heteroassociation experiment indicating binding and stoichiometry for chymotrypsin and bovine pancreatic trypsin inhibitor. FIG. 5 shows the results of a heteroassociation negative control experiment. The data are consistent with no binding between chymotrypsin and lysozyme. FIG. 6 shows the results of a series of chymotrypsin self association experiments at differing solution salinities. BRIEF DESCRIPTION OF INVENTION As previously discussed, methods of observing particle association with DLS has been explored for some time, however, the further step of measuring a comprehensive series of concentrations or ratios, followed by parametric modeling and calculation of association constants, stoichiometry, and conformations had neither been proposed nor demonstrated prior to the inventive methods described in the publication, authored in part by the inventors, Hanlon et al. “Free-solution, label-free protein protein interactions characterized by dynamic light scattering” Biophysical Journal, 2010, v.98, p 297-304, and described herein. We also specify that the method described in the paper may be used to identify the optimal ratio of two proteins for achieving the maximum amount of association, and thus the largest average solution hydrodynamic radius. This ratio can then be used to screen for small molecule chemical inhibitors, as inhibition would then result in the largest possible change in solution hydrodynamic radius. Although the optimized ratio may often be the best choice for a large scale screen, other ratios may be used. This technique is also not limited solely to screening of inhibitors, as other effectors/modulators may also be identified with the inventive method described herein. An additional benefit of this method is that it may be used to pre-screen the chemical libraries for aggregation. Aggregated compounds can act as “promiscuous” inhibitors, and yield false positive. Dynamic light scattering is an excellent way of testing for these aggregates, as documented in Feng et al., Nature Chemical Biology, 2005, v.1, p. 146-148. High throughput screening for effectors which modulate the solution viscosity by effecting changes on the interacting particles may also be identified by this method, although an internal standard such a nano-sized polystyrene sphere or other internal standard may be employed in the sample solution. DLS measurement of solution viscosity was recently detailed by He et al., “High throughput dynamic light scattering for measuring viscosity of concentrated protein solutions,” Analytical Biochemistry, 2010, accepted for publication. The key objective of the present invention is to provide a high throughput method for identification of small molecule effectors/modulators of particle interactions through the screening of large chemical libraries, using dynamic light scattering to monitor changes in hydrodynamic radius of optimized or non-optimized solutions. An additional objective is to provide a high throughput method of screening for said effectors using another aspect of DLS data, such as a change in the measured viscosity, time dependent changes, or some other variable determined by DLS. An additional objective is to provide a high throughput method of screening libraries of particles. An additional objective of the inventive method disclosed is the means by which all of the stoichiometry and association constants that are extracted from the static light scattering concentration gradient method, are derived equivalently from DLS measurements, with the additional yield of associated species conformational information. An additional objective of our inventive method is to provide means to reduce the total quantity of sample required for extraction of said stoichiometry and association constants. A further objective of our inventive method is the establishment of a suitable means by which the hydrodynamic radius of each complex may be modeled using the hydrodynamic radii of its constituent molecules. A further objective of our invention is to permit all measurements to be made at considerably greater speed by means of a high throughput device. Another objective of our inventive method is the ability to measure the association constants under a variety of different environmental conditions such as temperature, storage periods, packaging, etc. A further objective of our invention is to characterize the effects, of small molecules that may modulate protein associations. Our invention allows the characterization of the association constants between the associating particles and their modulators. An inventive free-solution method is described that uses dynamic light scattering for the high throughput detection of small molecule effectors of particle interactions. The method may also be used to screen libraries of particles. The method may also be used to characterize the equilibrium association constants and the stoichiometry of reversible complexes. The method is high-throughput with low sample requirements For self-association, a series of solutions are made containing different concentrations of the sample molecule, all in the same solvent. For heteroassociation, the method begins with the mixing of two stock solutions, one of each molecule in the same solvent, at varying ratios beginning, for example, with 100% of the first molecule and 0% of the second molecule and ending with 0% of the first molecule and 100% of the second molecule. Any other series of varying ratios may be used, as well. Additionally, for either self- or hetero-association determinations, a modulator may be added to the solutions, and its effects quantified. Each member solution of the series so prepared is generally illuminated with a fine laser beam and the fluctuating light scattered by said member is processed to yield its corresponding autocorrelation function. The resultant autocorrelation function data, one data set for each member ratio prepared, are then processed according to the following four-step procedure: 1) Modeling the relative concentration of each molecular component in solution: The concentrations of all components in a solution at a given time are calculated from postulated stoichiometries, association constant(s), K a , and the known a priori concentrations of the stock solutions of the constituent molecule(s). 2) Modeling the translational diffusion coefficient for associated molecules: Models describing the conformation of associating species are parameterized and then used to calculate the translational diffusion coefficient, and thence its hydrodynamic radius, r h , for each of the self- or hetero-associated species. 3) Modeling DLS data based upon above concentration and associated r h models: DLS results are calculated based on the known molar masses, the parameterized relative species concentrations, and the parameterized translational diffusion coefficients. 4) Fitting modeled DLS results to DLS measurements: The parameterized DLS results are then compared to the actual DLS measurements and a best fit of the parameters derived. A variety of different parameterized models of association constants may then be compared to a single datum or set of data. In this manner, the most probable parameter values are derived. Alternatively, of course, a specific parameter set may be assumed ab initio, and the corresponding stoichiometry and association constant or constants of the complexes in solution determined. Following the initial characterization, the particle mixture demonstrating the highest hydrodynamic radius may be used for a large scale screen of chemical libraries, where a drop in the solution hydrodynamic radius is a positive hit of the screen. Alternately, the solution may be optimized to demonstrate an increase of the solution hydrodynamic radius to screen for an association promoter, or any change in signal as determined by the user to be the most indicative of the desired effect. In addition, libraries of modified/altered particles may be screened against the reacting partner(s). The most substantial change in the solution hydrodynamic radius could be interpreted as the most promising hit. In addition, multiple systems could be screened simultaneously. DETAILED DESCRIPTION OF THE INVENTION For illustrative purposes, we shall focus specifically upon the interactions of protein molecules, though the techniques disclosed are applicable to all the other particle types as specified in the Background section of this specification. Again, whenever the term “molecule” is used, it will be understood that the word “particle” may be substituted therefore in most cases without any limitations implied upon the inventive method. The method begins with sample preparation to be described presently. The DLS data are collected, and then analyzed in a four-step procedure. First, the concentrations of all components in a solution at a given time are calculated from postulated stoichiometries, association constant(s), K a , and the known a priori concentrations of the stock solutions of the constituent molecule(s). Second, the translational diffusion constant, and hence its corresponding hydrodynamic radius, of each associated species is modeled. Third, the modeled concentration data and modeled hydrodynamic radius data are combined to model the expected dynamic light scattering data at each sample ratio. Fourth, a best fit of the models to the collected DLS data is obtained. Thus, some or all parameters are adjusted to produce a best fit to the DLS data. Such fitting might be achieved using a least squares method, for example. These four steps of data analysis are discussed in detail in the following, and variations are possible, as would be apparent to one skilled in the art of DLS or particle associations. There are many different ways of preparing samples in varying concentrations or ratios, and there are many different DLS systems capable of making the measurements required for our invention. A series of different concentrations, or ratios of two components, may be made manually, or automatically. Automatic methods include commercially available fluid handling robots, inline dilution/concentration systems, automated multiple syringe systems, autosamplers with pre-treatment capability, etc. Below we outline one such sample preparation and one such measurement system based on the use of a high throughput method using microtiter plates. In this example, to prepare the sample series for both self- and hetero-association, two stock solutions are mixed manually. For analysis of hetero-association, a high concentration, on the order of 0.5 mg/mL, solution of each pure molecule is prepared in the same solvent. For larger molecules, such as those greater than, say, 50 kDa, lower concentrations may be used. For analysis of self-association reactions, the molecular solution is prepared at the highest concentration to be tested; the second solution is the pure solvent in which the sample molecule was prepared. All solutions are filtered through a 0.02 μm filter. For either type of analysis, aliquots of the two solution mixtures are dispensed into a 1536 well microtiter plate in a series of ratios from 100% A:0% B to 0% A:100% B, or some subset thereof, where the number of ratios prepared depends upon the desired detail of analysis. Typically, 10-20 ratios are used. Following the dispensing of the sample, the microtiter plate is centrifuged at a rate and duration sufficient to remove any bubbles present in the samples; typically 1000 g for 15 seconds. Wells may then be covered to avoid evaporation, for example, by dispensing approximately 10 μL of paraffin oil into each well. The plate is then re-centrifuged prior to being placed into a dynamic light scattering instrument programmed, for example, to make 25 one-second dynamic light scattering measurements per well. Other sample holding systems may be used for with this inventive method. Multiwell plates are only one possibility. Step 1: Modeling Concentrations of all Components in Solution For the reaction A+B AB the equilibrium association constant is given as K AB = [ AB ] [ A ] ⁡ [ B ] . For known total molar concentrations of two species [A tot ] and [B tot ], and known or modeled association constant, the molar concentrations of free solution unassociated [A] and [B] and molar concentrations of associated species, such as [AB], may be derived by fitting the data to the model selected. DLS measurements are made of each mixture over a range of [A tot ]:[B tot ] ratios to provide sufficient data to extract the reaction equilibrium constant in terms of the model selected. This basic approach may be applied generally to species that are reversibly self- and/or hetero-associating with any assumed stoichiometry, as shown, for example by Cantor and Schimmel, Chapter 15, “Ligand interactions at equilibrium” in Biophysical Chemistry, Part III: The Behavior of biological macromolecules , W.H. Freeman and Company, New York, N. Y., 1980. Three examples are given below. EXAMPLE 1 Hetero-Association: A+BAB Species A and B associating to form species AB with equilibrium association constant K AB : [ A tot ]=[A]+[AB] Equation [B tot ]=[B]+[AB] [AB]=K AB[A][B] which reduces to: ⁢ [ A ] = [ A tot ] ( 1 + K AB ⁡ [ B ] ) ⁢ [ B ] = 1 2 ⁢ { ( [ B tot ] - [ A tot ] ) - 1 K AB ⁢ ( 1 - { 1 + 2 ⁢ K AB ⁡ ( [ B tot ] + [ A tot ] ) + K AB 2 ⁡ ( [ B tot ] - [ A tot ] ) 2 } 1 2 ) } EXAMPLE 2 Self-Association: A+AAA Species A self-associating to form species AA with equilibrium association constant K AA : [A tot ]=[A]+ 2 [AA] [AA]=K AA [A] 2 Which reduces to: [ A ] = 1 4 ⁢ K AA ⁢ ( { 1 + 8 ⁢ K AA ⁡ [ A tot ] } 1 2 - 1 ) EXAMPLE 3 Three Binding Components: A+BAB, A+CAC Species A, B, and C, associating to form species AB and AC with association constants K AB and K AC . This example pertains to association modulators. Consider species A and B to be the primary associating species, and species C to be a modulator of those associations, e.g. a small molecule inhibitor. In this case, the presence of [AC] reduces the availability of free [A] in solution, and so reduces the quantity of [AB] in solution. The molar concentrations of all species may be found using the set of equations: [A tot ]=[A]+[AB]+[AC] [B tot ]=[B]+[AB] [C tot ]=[C]+[AC] [AB]=K AB [A][B] [AC]=K AC [A][C] The above five equations may be reduced to a set of three equations and three unknowns, and solved. To one skilled in the art it is clear that using the above technique we may model the concentrations in solution for any combination of A and B with any stoichiometry. It is also clear to one skilled in the art that any number of species inter-associating may be similarly modeled, and that self-association may be modeled simultaneously with heteroassociation. Step 2: Modeling Translational Diffusion Coefficient for Associated Species For species that are associating, the net size of the associating species will be larger than the size of the individual component species, and the corresponding translational diffusion coefficient will be smaller than that of the component species. In general, it is not possible to exactly calculate the size and shape of the associating species, although in special cases additional information may provide an estimate of the size, or constrain the possible sizes. There are many ways to model the hydrodynamic radius of associating species for example, those shown in FIG. 2 and several of which are discussed below: 1) Assume hard spheres. For combinations of hard spheres touching at single points, the translational diffusion coefficient and corresponding hydrodynamic radii may be calculated numerically as shown by J. G. de la Torre and V. A. Bloomfield in Biopolymers , Vol. 16, 1747 (1977). For example, for an association consisting of two hard spheres of equal radii r touching at a point, the translational diffusion coefficient of the associating object is found to be ¾ of the translational diffusion coefficient of one of the constituent objects. The hydrodynamic radius for that object is therefore 1.33 times the hydrodynamic radius for a single hard sphere. A model assuming hard sphere associations with a linear conformation will give the maximum reasonable hydrodynamic radius for a composite object, unless by associating with each other the basic shape of the constituent objects change. 2. Assume “droplet”—the mass changes to some power of the radius. The volume and radius of a sphere are related by the relation v=4/3πr 3 . For two spheres of radii r 1 and r 2 which associate into one large sphere where the volumes are conserved, the resulting radius of the large sphere will be r={r 1 3 +r 2 3 } 1/3 . This “droplet” model of association, where the constituent species act as droplets of fluid combining to form a larger droplet, results in the most compact possible associating structure and the smallest possible change in hydrodynamic radius. Given this model, for two constituent objects having the same radius, the radius of the composite object will be 2 1/3 =1.26 times the radius of the constituent objects. While many systems may be well approximated by droplets coming together, others clearly will not. However, the increase in the hydrodynamic radius may be modeled in a similar way for objects that do not have the density of hard spheres. Proteins which are folded, for example, are found to generally have a hydrodynamic radius which varies as the molar mass to the power of 1/(2.34), rather than the power of ⅓ as would be expected for hard spheres as described by Claes, et al. in Chapter 5 of Laser Light Scattering in Biochemistry Eds. S. E. Harding, et. al., 1992, The Royal Society of Chemistry, Cambridge, UKHarding et al. Proteins are coiled and folded, rather than being solid, and so this result is not surprising. Proteins which are associating with one another will likely not form as compact a structure as a protein which simply folds, and so it is reasonable to assume that associating proteins could have a hydrodynamic radius which varies as the molar mass to the power (1/a), where a is a number less than 2.34. By this line of reasoning, we may model the hydrodynamic radius of an associating species as r = { ∑ i ⁢ r i a } 1 a where a may be fixed to some value, or may be allowed to vary as a parameter when fitting. From the above discussion it is clear that the way in which constituent objects associate has a significant bearing on the hydrodynamic radius of the composite object. For two objects of equal radii r associating, the hard sphere model yields 1.33r, the droplet model with a=3 yields a hydrodynamic radius for the composite object of 1.26r, and the droplet model with a=2 yields 1.41r. We demonstrate below that the inventive methods may be used to estimate the way in which species associate, and so provide valuable information regarding the conformation association. Step 3: Modeling DLS Data Based Upon Above Concentration and Associated r h Models DLS measurements determine either the field-field or the intensity-intensity autocorrelation function, for a single or multiple species in solution, as described by Chu, in sections 3 and 4 of Laser Light Scattering, Basic Principles and Practice (2nd Ed., Dover Publications, Mineola New York (2007)). For a single species in solution, the functions are relatively simple. Polydisperse solutions, i.e., solutions containing non-identical species, have autocorrelation functions with greater complexity. The field-field autocorrelation function, g (1) (τ), of a single species undergoing thermal translational diffusion (Brownian motion) is a simple exponential function given as g (1) (τ)=exp(−Γτ) where τ is the autocorrelation delay time, Γ is the decay rate given by Γ=q 2 D  (3) where D is the translational diffusion coefficient, and q is the scattered wave vector given by q=(4πn/λ 0 )sin(θ/2), where n is the solvent refractive index, λ 0 is the vacuum wavelength of the light used in the measurement, and θ is the scattering angle. For a spherical object of radius r, the translational diffusion coefficient is given by the Stokes-Einstein relation D = k B ⁢ T 6 ⁢ π ⁢ ⁢ η ⁢ ⁢ r ( 4 ) where k B is the Boltzmann constant, T is the absolute temperature, and η the solution viscosity. The above theory is detailed by F. Reif in section 15.6 of Fundamentals of Statistical and Thermal Physics (McGraw-Hill, New York (1965)). The hydrodynamic radius r h measured in a DLS experiment is the radius of a sphere having the same translational diffusion coefficient as the species under study, and as such is considered an equivalent spherical radius. The intensity-intensity autocorrelation function, g (2) (τ), for a single species in solution is related to the field-field autocorrelation function by the Seigert relation g (2) (τ)=1+β[ g (1) (τ)] 2 where the amplitude β is related to the number of coherence areas viewed in a measurement volume. For a single species in solution, the intensity-intensity autocorrelation function therefore becomes g (2) (τ)=1+β exp(−2 q 2 D τ). By measuring the normalized photon count autocorrelation function, the intensity-intensity autocorrelation function is obtained. For a single species solution, the data may be fit to a simple exponential function, as shown in FIG. 1 , and the hydrodynamic radius may be extracted from the decay rate. For polydisperse solutions, the analysis becomes more complex. In this case the field-field autocorrelation function is the sum over the decay rates of all the species in solution, weighted by the relative amount of light scattered into the detector by each species, such that g ( 1 ) ⁡ ( τ ) = ∫ 0 ∞ ⁢ G ⁡ ( Γ ) ⁢ exp ⁡ ( - Γ ⁢ ⁢ τ ) ⁢ ⅆ Γ ( 5 ) Here, G(Γ)dΓ is the fraction of scattered light intensity due to species with decay rates from Γ to Γ+dΓ. The intensity-intensity autocorrelation function therefore becomes: g ( 2 ) ⁢ τ = 1 + β ⁡ [ ∫ 0 ∞ ⁢ ⅇ - Γ τ ⁢ G ⁡ ( Γ ) ⁢ ⁢ ⅆ Γ ] 2 ( 6 ) The relative contributions to G(Γ) by the different species are given by the relative intensities of light scattered by the different species. The intensity of scattered light for a species of a particular molar mass M and mass concentration c is given by B. Zimm in J. Chem. Phys., vol. 16 , no. 12, 1093-1099 (1948) as R=K*McP ( r g ,θ)[1−2 A 2 McP ( r g ,θ)]  (7) where R is the excess Rayleigh ratio, meaning the ratio of the light scattered from the solute and the incident light intensity, corrected for size of scattering volume and distance from scattering volume. P(θ) is the form factor or scattering function which relates the angular variation in scattering intensity to the root mean square radius, r g , of the particle. A 2 is the second virial coefficient, a measure of solvent-solute and solute-solute interaction and is the second term in the virial expansion of osmotic pressure. A 2 enters into the light scattering equation as a correction factor for concentration effects due to intermolecular interactions influencing the scattering light intensity. M is the molar mass, c is the solute concentration in g/mL, and K* is defined as follows: K * = 4 ⁢ π ⁢ ⁢ n 0 2 N A ⁢ λ o 4 ⁢ ( ⅆ n ⅆ c ) 2 where n 0 is the solvent refractive index, N A is Avagadro's number, λ 0 is the vacuum wavelength of incident light, and dn/dc is the specific refractive index increment. For a distribution of species with a distribution of r h and associated distribution of Γ, with corresponding distributions of M(Γ), c(Γ), r g (Γ), and A 2 (Γ), using equations, 3, 4, 6, and 7, the expected distribution of exponential functions which would be observed in an intensity-intensity autocorrelation DLS measurement may be seen to be G ⁡ ( Γ ) = R ⁡ [ M ⁡ ( Γ ) , c ⁡ ( Γ ) , r g ⁡ ( Γ ) , A 2 ⁡ ( Γ ) ] ∫ 0 ∞ ⁢ R ⁡ ( M ⁡ ( Γ ) , c ⁡ ( Γ ) , r g ⁡ ( Γ ) , A 2 ⁡ ( Γ ) ) ⁢ ⁢ ⅆ Γ . ( 8 ) Equation (8) may be simplified for some cases. If all species involved in the measurement have root mean square radii about a factor of 50 or more smaller than the wavelength of light in the solution being used for measurement (i.e. r g <10 nm for 660 nm light in water), then the scattering function P(θ) approaches 1.0 regardless of the angle of measurement and may be disregarded. A second simplification may be made for the case where for all species involved in the measurement 2A 2 McP(θ)<<1, enabling this term including to be neglected. With both these assumptions, the intensity of scattered light from a single species is given by R=K*Mc   (9) and Equation (8) simplifies to G ⁡ ( Γ ) = M ⁡ ( Γ ) ⁢ c ⁡ ( Γ ) ∫ 0 ∞ ⁢ M ⁡ ( Γ ) ⁢ c ⁡ ( Γ ) ⁢ ⁢ ⅆ Γ . ( 10 ) Inventive steps 1 and 2 described above generate a modeled distribution of species, each species having a particular concentration, molar mass, and hydrodynamic radius with associated decay rate. Given that modeled distribution, Equation (8), or if appropriate Equation (10), may be combined with Equation (5) or (6) to generate the modeled field-field or intensity-intensity autocorrelation function, respectively. Using Equation (10), the intensity-intensity autocorrelation function may be seen to be g ( 2 ) ⁡ ( τ ) = 1 + β [ ∫ 0 ∞ ⁢ M ⁡ ( Γ ) ⁢ c ⁡ ( Γ ) ⁢ exp ⁡ ( - Γτ ) ⁢ ⁢ ⅆ Γ ∫ 0 ∞ ⁢ M ⁡ ( Γ ) ⁢ c ⁡ ( Γ ) ⁢ ⁢ ⅆ Γ ] 2 . Step 4: Fitting Modeled DLS Results to DLS Measurements. Procedure A: Directly Fitting all Autocorrelation Functions Performing inventive steps 1, 2, and 3 permit the calculation of the expected autocorrelation functions for all samples measured. All autocorrelation functions may thus be fit, either individually or in concert, with association constants, conformation parameters, and hydrodynamic radii as parameters in the fit. In this way the parameters which most accurately represent the data may be determined. Any of the parameters in the fit may be fixed to known values or may be varied as a part of the fitting procedure. Procedure B: Fitting G(Γ) Alternatively, estimates for the distribution G(Γ) at each concentration may found from the autocorrelation data, and compared to the modeled G(Γ) to determine the best fit parameters. It is not possible to uniquely determine G(Γ) from data of g (1) (τ) or g (2) (τ), and direct comparison between modeled and measured G(Γ) is not possible. However, it is possible to estimate G(Γ) from the autocorrelation function using the method of regularization, as discussed by S. W. Provencher in Makromol. Chem., vol. 180, 201-209 (1979), and developed further by many others. Procedure C: Fitting Derived Quantities The methods of fitting procedures A and B can be mathematically involved and computationally intensive. Instead, each autocorrelation function may be analyzed separately, generating just one or two derived values which contain most of the information characterizing the distribution G(Γ). Those derived quantities may then be compared to the values expected by the modeling, and the modeled parameters may thus be determined. There are many functional forms used to fit individual autocorrelation functions. One class of functions generally used to fit autocorrelation function data is generated by assuming some functional form for G(Γ), such as a Gaussian distribution, and calculating the corresponding expected g (1) (τ) or g (2) (τ). For the example of a Gaussian distribution of G(Γ), the center and width of the Gaussian distribution are two of the free parameters used when fitting the autocorrelation function data. A second class of functions used to fit autocorrelation function data use an expansion of the distribution G(Γ) into moments of the distribution, and calculating the corresponding expected g (1) (τ) or g (2) (τ). The most commonly used implementation of this class of functions is the method of cumulants expansion, as described by D. E. Koppel in J. Chem. Phys. 57, 4814-4820 (1972). The method of cumulants may be used to fit the autocorrelation data to determine the first and second cumulants, which are identical to the first and second moments of the distribution G(Γ). The first and second moments of this distribution are defined as μ 1 = Γ _ = ∫ 0 ∞ ⁢ Γ ⁢ ⁢ G ⁡ ( Γ ) ⁢ ⁢ ⅆ Γ ⁢ ⁢ and ⁢ ⁢ μ 2 = ∫ 0 ∞ ⁢ ( Γ - Γ _ ) 2 ⁢ ⁢ G ⁡ ( Γ ) ⁢ ⁢ ⅆ Γ respectively. The first moment is the mean decay rate, and is often designated by the symbol Γ . The second moment is proportional to the width of the distribution G(Γ), and is often used in the definition of the polydispersity of a measured sample as Pd = μ 2 μ 1 2 . Both the first and second moments of the modeled distribution G(Γ) may be calculated for the models described above and fit to the values for the first and second moment derived from data for all concentrations, and so the modeled parameters may be extracted. Below we provide an example of this procedure for the case of comparing the mean decay rate between the data and models of association. The mean decay rate Γ may be used to calculate an equivalent radius spherical species, termed the average hydrodynamic radius, r avg . Given species A and B which satisfy the conditions making Equation (9) valid, having molar masses M A and M B , concentrations c A and c B , and hydrodynamic radii r hA and r hB , with associated translational diffusion coefficients D A and D B and corresponding decay rates Γ A and Γ B , the function G(Γ) is given by G ⁡ ( Γ ) = δ ⁡ ( Γ - Γ A ) ⁢ M A ⁢ c A + δ ⁡ ( Γ - Γ B ) ⁢ M B ⁢ c B M A ⁢ c A + M B ⁢ c B where δ(x) is the Dirac delta function having a value of 1 for x=0 and 0 otherwise. The mean decay rate becomes Γ _ = ∫ 0 ∞ ⁢ Γ ⁢ ⁢ G ⁡ ( Γ ) ⁢ ⁢ ⅆ Γ = Γ A ⁢ M A ⁢ c A + Γ B ⁢ M B ⁢ c B M A ⁢ c A + M B ⁢ c B Expressing the decay rates in terms of the equivalent hydrodynamic radii and cancelling common terms, we find 1 r avg = ( 1 / r A ) ⁢ M A ⁢ c A + ( 1 + r B ) ⁢ M B ⁢ c B M A ⁢ c A + M B ⁢ c B Where r avg is the hydrodynamic radius corresponding to the mean decay rate Γ . This may be rewritten as r avg = M A ⁢ c A + M B ⁢ c B ( M A ⁢ c A / r A ) + ( M B ⁢ c B / r B ) We may extended this analysis for an arbitrary number of species to r avg = ∑ i ⁢ ⁢ M i ⁢ c i ∑ i ⁢ ⁢ M i ⁢ c i / r i ( 11 ) Equation (11) is specific for the case of validity of Equation (9), but may be expressed more generally by substituting Equation (7) for Equation (9) during the derivation. Example of Steps 1-4: As an example of the inventive method, we consider two species A and B associating to form species AB with equilibrium association constant K AB : A+B AB. In this example we will use fitting procedure C, using the average hydrodynamic radius found by fitting the autocorrelation function measured for each sample to a cumulants model. We will assume that Equation (11) is valid. The mass concentrations used in Equation (11) are given by multiplying the molar concentrations by the molar mass of each species, giving r avg = M A 2 ⁡ [ A ] + M B 2 ⁡ [ B ] + ( M A + M B ) 2 ⁡ [ AB ] ( M A 2 ⁡ [ A ] / r A ) + ( M B 2 ⁡ [ B ] / r B ) + ( ( M A + M B ) 2 ⁡ [ AB ] / r AB ) The modeled molar concentrations for A and B, and AB are given by the following equations in terms of total molar concentrations [A tot ] and [B tot ] as [ B ] = 1 2 ⁢ { ( [ B tot ] - [ A tot ] ) - 1 K AB ⁢ ( 1 - { 1 + 2 ⁢ ⁢ K AB ⁡ ( [ B tot ] + [ A tot ] ) + K AB 2 ⁡ ( [ B tot ] - [ A tot ] ) 2 } 1 2 ) } ⁢ ⁢ [ A ] = [ A tot ] ( 1 + K AB ⁡ [ B ] ) and [AB]=K AB [A][B]. Given hydrodynamic radii r A and r B , for this example we will assume r AB ={r A a +r B a } 1/a . If molar masses M A and M B and hydrodynamic radii r A and r B are assumed known, and [A tot ] and [B tot ] are known from sample preparation, then association constant K AB and the association conformation parameter a are the only free parameters in a fit between the data and the model. The high throughput screening may follow the complete characterization of the interaction. Alternatively, once the molar ratio/concentration showing the maximum hydrodynamic radius is determined, full characterization may be bypassed if the sole point of interest is discovery of a protein protein interaction inhibitor/promoter/effector. Or, a ratio/concentration of the particles may be chosen based on other criteria. The library may be added before or after the addition of the protein solution to the plate. The optimal mixture of protein ‘A’ and protein ‘B,’ may then be placed in the wells of a microtiter plate. The hydrodynamic radius of each well would then be measured. The plate may be measured in the DLS plate reader immediately, or after a set period to allow the reaction with the library compounds to occur. Alternately, the plate could be scanned continuously over a set time period. Depending on the time constant of the potential inhibition, the change in the hydrodynamic radius may be possible to monitor through time, and the kinetics of the interaction quantified. Sample holding systems are not limited to multiwell plates. Other systems may be used as well. Additional Application: Measuring the equilibrium constant over a series of temperatures can yield thermodynamic information about the association: At equilibrium, there is no net change in the Gibbs free energy of a system, and the relationship of ΔG°, the free energy change of a reaction when all its reactants and products are in their standard states, can be written as: ΔG°=−RT ln K eq where R is the ideal gas constant, and T is absolute temperature. Substituting in the Gibbs free energy at constant temperature and pressure, where H and S reflect enthalpy and entropy, respectively: ΔG°=ΔH°−TΔS°, yields the manner in which the equilibrium constant varies with temperature: ln ⁢ ⁢ K eq = - Δ ⁢ ⁢ H° R ⁢ ( 1 T ) + Δ ⁢ ⁢ S° R The derivation of this function as described by D. Voet et al., Biochemistry, 2 nd Ed John Wiley & Sons, Inc., New York, N.Y., (1995) Chapter 3, affects the reasonable assumption that ΔH° and ΔS° are independent of temperature. A plot of ln K eg vs. 1/T yields a straight line of slope −ΔH°/R and an intercept of ΔS°/R. The plot, known as a van't Hoff plot, enables the values of ΔH° and ΔS° to be determined from measurements of K eq at two or more temperatures. Further Examples Having fully described the invention above, the following examples are given solely for illustrative purposes and are not intended to limit the scope of the invention in any manner. In FIG. 3 the soybean trypsin inhibitor (molar mass of 22 kDa) and chymotrypsin (molar mass of 25 kDa) heteroassociation experiment results are shown. The r h is plotted as a function of the molar ratio of the two proteins. Circle symbols show the data, the solid line shows the fit. This data was fitted with an incompetent fraction of chymotrypsin, meaning that it was assumed that a portion of the chymotrypsin in solution is unable to associate with the soybean trypsin inhibitor. The soybean trypsin binding site on chymotrypsin is known to possess some heterogeneity, as shown by Erlanger et al. in their 1970 paper, “Operation Normality of α-Chymotrypsin solutions by a sensitive potentiometric technique using a fluoride electrode”, Analytical Biochemistry, 33, 318-322. Incorporating an incompetent fraction into the fitting allows for the exclusion of the non-participating enzyme fraction. For this heteroassociation, the association constant was found to be 3.8×10 6 M −1 , with a corresponding a value of 2.26. The binding stoichiometry was found to be 2:1 chymotrypsin:soybean trypsin inhibitor, in accordance with the known association ratio. The additional data set in FIG. 3 , represented by open squares, is the same experiment repeated in the presence of 500 mM 4-(2-Aminoethyl) benzenesulfonyl fluoride hydrochloride (AEBSF). AEBSF, is a small molecule known to be a serine protease inhibitor which binds to the chymotrypsin active site, thus inhibiting the binding of the soybean trypsin inhibitor. Since AEBSF is a small molecule (r h <<1 nm), the decay rate of the autocorrelation function associated with AEBSF is faster than may be observed with conventional DLS technology, and the presence of that molecule is not observed in the DLS signal. When AEBSF associates with chymotrypsin, the r h of the associated species is not measurable different from that of unassociated chymotrypsin. The increase in r h seen in the absence of AEBSF is not observed in this experiment. This shows that the increase in r h is due to specific site binding of the two proteins, an interaction which is completely inhibited by AEBSF. This negative control also demonstrates the potential of the technique for large scale screening of small molecule modulators of particle—particle associations. Additionally, the association constant of AEBSF with chymotrypsin may be measured using this invention by repeating the chymotrypsin/soybean trypsin inhibitor/AEBSF experiment and lowering the concentration of AEBSF until some increase in r h is seen, and modeling the associating species. In FIG. 4 the bovine trypsin inhibitor (6.5 kDa) and chymotrypsin heteroassociation experiment results are shown. The r h is plotted as a function of the molar ratio of the two proteins. Circle symbols show the data, while the solid line shows the fit. For this heteroassociation, the data were found to be consistent with an association constant of 6×10 6 M −1 with an a value of 3, and the binding stoichiometry was found to be 1:1 chymotrypsin:bovine trypsin inhibitor, in accordance with the known association ratio. This association constant value closely matches the 6.3×10 6 M −1 value reported by Kameyama et al., Biophysical Journal , Vol. 90, 2164-2169, (2006), who analyzed the two proteins in the same buffer conditions, using static light scattering. For comparison, a fit using association constants of 0.1×10 6 M −1 is shown by broken lines. For these data, higher association constants (up to infinity) fit the data equally well as the solid line shows, and so in this case it is possible only to provide a minimum value for the association constant. In FIG. 5 the negative control of chymotrypsin and lysozyme (14.4 kDa) is shown. The r h is plotted as a function of the molar ratio of the two proteins. Open square symbols show the data, while the solid line shows the fit. Although the two proteins are oppositely charged under the experimental conditions of pH 6.7, the association constant is found to be 0, reflecting an absence of any specific interaction. This control shows that only proteins with specific binding will be detected in this technique; non-associating proteins will not yield an association constant. In FIG. 6 , results of self-association experiments are shown. Here, the association constant for the dimerization of α-chymotrypsin is determined as a function of buffer salinity. On the left graph, the r h is plotted as a function of the protein concentration. Open symbols show the data, while solid lines indicate the fits. Squares, diamonds, triangles, circles, and stars represent data with solution concentrations of 50, 162.5, 275, 387, and 500 mM NaCl respectively. Note as the salinity increases, the r avg increases, corresponding to an increase in association constant. The fitted association constants extracted from each data set are graphed on the right, as a function of sodium chloride concentration. Values closely match those determined with static light scattering, as reported by M. Larkin and P. Wyatt in chapter 8 of Formulation and Process Development Strategies for Manufacturing of a Biopharmaceutical , John Wiley & Sons, Inc., New York, N.Y., in press 2008. Many embodiments of this invention that will be obvious to those skilled in the art of dynamic light scattering measurements, particle interactions, or high throughput screening are but simple variations of the basic invention herein disclosed. Accordingly,

This invention enables high throughput detection of small molecule effectors of particle association, as well as quantification of association constants, stoichiometry, and conformation. “Particle” refers to any discrete particle, such as a protein, nucleic acid, carbohydrate, liposome, virus, synthesized polymer, nanoparticle, colloid, latex sphere, etc. Given a set of particle solutions having different concentrations, dynamic light scattering measurements are used to determine the average hydrodynamic radius, r avg , as a function of concentration. The series of r avg as a function of concentration are fitted with stoichiometric association models containing the parameters of molar mass, modeled concentrations, and modeled hydrodynamic radii of the associated complexes. In addition to the r avg value analysis, the experimental data may be fit/analyzed in alternate ways. This method may be applied to a single species that is self-associating or to multiple species that are hetero-associating. This method may also be used to characterize and quantify the association between a modulator and the associating species.

TECHNICAL FIELD [0001] This present disclosure relates to the general field of computer aided design, drafting (“CAD”), manufacturing (“CAM”) and visualisation systems (individually and collectively “CAD systems”), product lifecycle management (“PLM”) systems, and similar systems, that manage data for products and other items (collectively, “Product Data Management” systems or PDM systems). BACKGROUND OF THE DISCLOSURE [0002] PDM systems manage PLM and other data. Improved methods and systems are desirable. SUMMARY OF THE DISCLOSURE [0003] Various disclosed embodiments include methods for identifying geometric clones in a modelling system, or simulating modifications to construction of a multi-part product. [0004] A method includes choosing a template of a geometric form and generating and storing a map of the template. The method includes identifying a candidate geometric form in the system, exploring the identified candidate geometric form from a start point until returning to the start point or reaching a branch and generating a map of the explored candidate geometric form. The method includes comparing the map of the explored candidate geometric form with the map of the template and labelling the candidate geometric form as a clone if it matches a predetermined portion of the template. [0005] A method includes choosing a template representing a sample, searching for candidates matching at least a predetermined portion of the template and labelling those candidates which match at least the predetermined portion of the template as geometric clones. [0006] A method includes modelling the product using a model. The method includes selecting one part of the multi-part product and identifying geometric forms comprising geometric clones, or inverted geometric clones of the selected part in the model. The method includes labelling identified clones, applying a modification to the part and to the labelled geometric clones and providing a representation of the modified product. [0007] The foregoing has outlined rather broadly the features and technical advantages of the present disclosure so that those skilled in the art may better understand the detailed description that follows. Additional features and advantages of the disclosure will be described hereinafter that form the subject of the claims. Those skilled in the art will appreciate that they may readily use the conception and the specific embodiment disclosed as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. Those skilled in the art will also realize that such equivalent constructions do not depart from the scope of the disclosure in its broadest form. [0008] Before undertaking the DETAILED DESCRIPTION below, it may be advantageous to set forth definitions of certain words or phrases used throughout this patent document: the terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation; the term “or” is inclusive, meaning and/or; and the term “controller” means any device, system or part thereof that controls at least one operation, whether such a device is implemented in hardware, firmware, software or some combination of at least two of the same. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. Definitions for certain words and phrases are provided throughout this patent document, and those of ordinary skill in the art will understand that such definitions apply in many, if not most, instances to prior as well as future uses of such defined words and phrases. While some terms may include a wide variety of embodiments, the appended claims may expressly limit these terms to specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS [0009] An example of method and data processing system according to the present disclosure will now be described with reference to the accompanying drawings in which: [0010] FIG. 1 is a block diagram of a data processing system in which an embodiment can be implemented; [0011] FIG. 2 is a flow diagram of a process in accordance with disclosed embodiments; [0012] FIG. 3 illustrates an example of a sample from which a template is produced and a potential clone, in accordance with disclosed embodiments; [0013] FIG. 4 provides more detail of the embodiment of FIG. 3 ; [0014] FIG. 5 provides more detail of the embodiment of FIG. 3 ; [0015] FIG. 6 illustrates further detail in accordance with the disclosed embodiments; [0016] FIGS. 7 a and 7 b illustrate another sample and clone in accordance with the disclosed embodiments; [0017] FIGS. 8 a and 8 b illustrate another sample and clone in accordance with the disclosed embodiments; [0018] FIG. 9 provides more detail in accordance with the disclosed embodiments; [0019] FIG. 10 illustrates an example of applying deterministic matching in an exemplary method in accordance with the disclosed embodiments; [0020] FIGS. 11 and 12 illustrate an example of the effect of differences in numbers of edges in an exemplary method in accordance with the disclosed embodiments; [0021] FIG. 13 illustrates the effect of multiple loop matching, in accordance with the disclosed embodiments; [0022] FIGS. 14 a , 14 b and 14 c illustrate the effect of multiple loop branching, in accordance with the disclosed embodiments; [0023] FIGS. 15 a , 15 b and 15 c provide more detail of the embodiment of FIGS. 14 a , 14 b and 14 c , in accordance with the disclosed embodiments; [0024] FIGS. 16 a and 16 b illustrate the effect of multiple boundary segment branching, in accordance with the disclosed embodiments; [0025] FIG. 17 illustrates the effect of dependency on the embodiment of FIGS. 16 a and 16 b , in accordance with the disclosed embodiments; [0026] FIGS. 18 a and 18 b illustrate combined mapping, in accordance with the disclosed embodiments; and, [0027] FIGS. 19 a , 19 b and 19 c illustrate the effect of features which generate cyclic graphs, in accordance with the disclosed embodiments. DETAILED DESCRIPTION [0028] The embodiments of FIGS. 1 to 19 used to describe the principles of the present disclosure in this document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged device. [0029] In CAD systems, a user may wish to model a design for an object, carry out tests to determine the behaviour of that object and modify the design in response to the outcome of the tests. At certain stages in the design process, the user may wish to make changes and then revert to the original, if the outcome is not as expected, or to trial a number of different changes in succession to determine which is to be used. However, the user is resistant to activities with long delays. Certain processes may be performed individually on elements of the design which are geometrically similar, wasting time and computing power. However, identifying such design elements manually is difficult and time consuming and in some cases just may not be practical to do. [0030] Direct modelling, or variational direct modelling may be used in any case where an object or article is represented as a solid, including machine parts, vehicles, equipment installations, building layouts, engineering structures, or chemical structures, but the disclosure is not limited to these applications. A three dimensional model allows mass, or weight of parts to be derived and interaction with other components in other systems can be determined. A variational direct modelling system describes the parameters of and relationships between features in an object model in terms of geometric constraints and dimensions. Such systems then use a solver process to process these constraints and dimensions, along with a multitude of ancillary constraints and dimensions required to maintain design intent, and the entire model is solved simultaneously. [0031] The present disclosure describes how to determine geometrically similar elements and associate these in such a way that they can be treated in a similar fashion in terms of processing, without each individual element having to be processed separately. The method automatically and rapidly determines whether or not an element which is geometrically similar to a given template exists within a specified environment. For the purpose of this description, such a geometrically similar element will be referred to as a geometric clone. Operations are more efficient when similar geometric forms can be identified and so behave similarly or be grouped and processed together. [0032] In a complex body such as an electrical machine, or a vehicle, or aircraft, there may well be multiple instances of parts which have a similar geometry. When modelling this complex body, each individual part is processed according to the changes which the designer wishes to apply. However, these changes all add to the computing requirement and extend the time required before an updated model can be rendered, after which the designer may wish to apply further tests to determine the validity of his design strategy. Reducing the time that this takes is beneficial. This is achieved by identifying geometric clones and labelling these so that during the processing phase, design changes can be applied to a designated template element or part and after the change has been applied, the effect is then copied to all clones of the template which have been identified. [0033] FIG. 1 illustrates an example of a data processing system in which an embodiment of the present disclosure may be implemented, for example a CAD system configured to perform processes as described herein. The data processing system 21 comprises a processor 22 connected to a local system bus 23 . The local system bus connects the processor to a main memory 24 and graphics display adaptor 25 , which may be connected to a display 26 . The data processing system may communicate with other systems via a wireless user interface adapter connected to the local system bus 23 , or via a wired network, e.g. to a local area network. Additional memory 28 may also be connected via the local system bus. A suitable adaptor, such as Wireless User Interface Adapter 27 , for other peripheral devices, such as a keyboard 29 and mouse 20 , or other pointing device, allows the user to provide input to the data processing system. Other peripheral devices may include one or more I/O controllers such as USB controllers, Bluetooth controllers, and/or dedicated audio controllers (connected to speakers and/or microphones). It should also be appreciated that various peripherals may be connected to the USB controller (via various USB ports) including input devices (e.g., keyboard, mouse, touch screen, trackball, camera, microphone, scanners), output devices (e.g., printers, speakers), or any other type of device that is operative to provide inputs or receive outputs from the data processing system. Further it should be appreciated that many devices referred to as input devices or output devices may both provide inputs and receive outputs of communications with the data processing system. Further it should be appreciated that other peripheral hardware connected to the I/O controllers may include any type of device, machine, or component that is configured to communicate with a data processing system. [0034] An operating system included in the data processing system enables an output from the system to be displayed to the user on display 26 and the user to interact with the system. Examples of operating systems that may be used in a data processing system may include Microsoft Windows™, Linux™, UNIX™, iOS™, and Android™ operating systems. [0035] In addition, it should be appreciated that data processing system 21 may be implemented as in a networked environment, distributed system environment, virtual machines in a virtual machine architecture, and/or cloud environment. For example, the processor 22 and associated components may correspond to a virtual machine executing in a virtual machine environment of one or more servers. Examples of virtual machine architectures include VMware ESCi, Microsoft Hyper-V, Xen, and KVM. [0036] Those of ordinary skill in the art will appreciate that the hardware depicted for the data processing system 21 may vary for particular implementations. For example the data processing system 21 in this example may correspond to a computer, workstation, and/or a server. However, it should be appreciated that alternative embodiments of a data processing system may be configured with corresponding or alternative components such as in the form of a mobile phone, tablet, controller board or any other system that is operative to process data and carry out functionality and features described herein associated with the operation of a data processing system, computer, processor, and/or a controller discussed herein. The depicted example is provided for the purpose of explanation only and is not meant to imply architectural limitations with respect to the present disclosure. [0037] The data processing system 21 may be connected to the network (not a part of data processing system 21 ), which can be any public or private data processing system network or combination of networks, as known to those of skill in the art, including the Internet. Data processing system 21 can communicate over the network with one or more other data processing systems such as a server (also not part of the data processing system 21 ). However, an alternative data processing system may correspond to a plurality of data processing systems implemented as part of a distributed system in which processors associated with several data processing systems may be in communication by way of one or more network connections and may collectively perform tasks described as being performed by a single data processing system. Thus, it is to be understood that when referring to a data processing system, such a system may be implemented across several data processing systems organized in a distributed system in communication with each other via a network. [0038] FIG. 2 is a flow diagram of a basic method illustrating the disclosure. The first step is to choose 140 a template for the part of the product which is being modelled, for example a cog teeth, or a nut, or a washer. Identifying geometric clones is most useful when considering parts which are present in multiple instances in the product. Having chosen the template, a mathematical map of the faces of the part represented by the template is generated 141 . The map indicates each of the faces or edges encountered by exploring the template faces or edges sequentially. The map for the template is stored for later use. Candidate geometric forms which may be similar to the template are identified 142 , for example by determining face and edge pairs which match a designated start face and edge of the template. In a two dimensional example, the template may comprise edges and vertices. In a three dimensional example, the template comprises edges and faces. [0039] Each identified candidate is explored 143 and a map for each candidate is generated 144 in a similar manner. In this example, the exploring comprises following the boundary of the start face, checking edges and adding new faces as they are detected. Each map is compared 145 with the map for the template. A range of tolerance which has been preset is used to determine whether the map of a candidate is within the range of tolerance which permits it to be deemed to be geometrically similar to the template. If the result falls within the acceptable range, then the modelled part is labelled as a geometric clone. If the result does not fall within the acceptable range, the candidate is discarded. The tolerance range may include a requirement for a specific portion of the template to be matched, or the tolerance range may comprise a minimum number of matches of the template and the candidate. For parts which are deemed to be geometrically similar a further check is made to see if any branches were encountered and if so, the process of exploring 143 , mapping 144 and comparing 145 , 146 is carried out 147 for each branch. More detail of the operation of the method is provided hereinafter. [0040] Given a set of template faces, this method rapidly identifies geometric clones together with their face mappings and consistent coordinate frames. The template faces are generally connected with a boundary to the environment and the clones are rigid transformations except at the boundary where they may vary. An example of a template and clone is shown here together with the face mapping and consistent coordinate frames. FIG. 3 illustrates a first example of a part A from which a template may be formed and then compared with a candidate part B to see if that part B can be deemed to be geometrically similar to part A. The sample part A has a connected set of faces 1 , 2 , 3 , 4 , 5 and the potential clone candidate part B has a connected set of faces 6 , 7 , 8 , 9 . 10 . The aim is to find geometric clones, so treatment faces at the boundary, such as blends and chamfers are ignored in the basic determination, as these take different geometric forms in each instance. This can be seen in FIG. 4 . The faces in the set, excluding any treatments, may be referred to as the ‘template’ and a subset of these that neighbour non-template faces are boundary faces. The edges between boundary faces and non-template faces are boundary edges and these may be collected into connected sets called boundary regions. Face 5 is a non-boundary face, faces 4 , 1 , 2 , 3 are boundary faces and faces 11 are ignored because they are treatments. [0041] The process starts by choosing a start face and edge from the set. In FIG. 3 , the start face chosen is labelled 5 and axes z 1 , x 1 are indicated. An edge may be chosen, for example circular edge 30 . The axes do not have to correspond to an edge. The start face and start edge chosen from the template start the process of graph building and matching. The choice of start face or start edge aims to reject unsuitable candidates as early as possible and optimise performance. For example, the circular edge 30 has a radius property which can be checked. A basic choice of start face to give good performance in a wide variety of situations is to choose based on likely rarity of the face itself according to a set of quickly testable local properties that are used when initially comparing them to the environment. This is in order that, at the later matching stage, candidate starting locations within the environment are at a minimum. [0042] There are various properties that can be used in choosing a start face and edge, including, but not limited to, searching for non-boundary faces and edges, which are preferable as their whole boundary can be used in testing. Using boundary faces instead is more complex. FIG. 4 illustrates examples of each. This shows one non-boundary face 5 , four boundary faces 4 , 1 , 2 , 3 and a number of treatment faces 11 . Another property is geometry type, for example, planes are very common and have no further properties to quickly check, whereas tori are rarer and also have two radii that can be checked very quickly. A property, such as edge count or loop count may be used; for example, a face with a large number of edges is fairly rare and serves as a better basis for checking than a face with four edges. [0043] An orthonormal coordinate frame, consisting of an origin, a Z direction and an X direction, is created from the template faces, i.e. z 1 , x 1 in FIG. 3 . The corresponding coordinate frame on a given candidate clone is created, illustrated as z 2 , x 2 in FIG. 3 with a given mapping to the template faces, as shown in the table 1 below. This allows a transform to be computed and used in the final exact geometric check. The origin chosen is typically a stable point, for example, an internal vertex, the centre of a geometry, or a parametric point on a non-analytic geometry. The Z direction may be an internal edge direction, the axial direction of a geometry, the normal of a plane, or the direction to another stable point. The X direction must be orthogonal to the Z direction, but can use similar types of point, or directions, as for the origin in the Z direction, but projected to the Z plane. [0000] TABLE 1 Sample 1 2 3 4 5 Clone 6 7 8 9 10 [0044] A topological graph is built to include all the faces, edges and loops of the template, attributed with local properties that are quick to check when matching and potentially including but not limited to: geometric type, geometric parameters, such as radii, half angle etc, loop count, loop type, edge counts, edge length, total edge/chord length, edge angle, convexity, etc. The choice of properties to include may vary, for example a boundary face will not compare edge count, so is chosen dynamically when building the graph. The order in which the properties are created is also important, and may vary between faces. For example, it may be better to check the number of edges first, if the template face has a large number. By contrast, another template face may have an untypical geometry type making that the first choice property. [0045] The method may analyse potential rotational symmetry of the template, which as well as providing useful additional output information and a superior choice of coordinate frame, also allows an important optimisation of the later search. To determine potential symmetry, the template is fully matched against itself using a fast match procedure and with an exact geometric check, described hereinafter. The method may include steps of adjusting the boundary, choosing a start face and edge, choosing a coordinate frame, building a graph, analysing for symmetries, gathering candidate faces, finding matches, in addition to a fast matching procedure and an exact geometric check. The template is searched for all candidate start face and edge pairs matching the local properties of the real start face and edge. This fast match procedure is applied to each of these candidate faces and edges and the total number of matches is used to infer any rotational symmetry of the template and possibly improving on the choice of coordinate frame. If there is only one match, this generally implies that there is no rotational symmetry. [0046] However, a further check is needed to see if an axial symmetry exists. This further check is for a common axis. A single match with no common axis implies no symmetry. The single X direction remains. For general, non-rotational, templates of this type, the coordinate frame is arbitrary, but for the benefit of downstream applications, some special cases can be applied. For example, in the example sample C shown in FIG. 5 the Z axis is chosen as the common sweep direction of the boundary faces or the direction of face 5 . [0000] TABLE 2 Sample 1 2 3 4 5 Self Match 1 1 2 3 4 5 [0047] The sample of FIG. 6 has five faces 31 , 32 , 33 , 34 , 35 . FIG. 6 and table 3 illustrate a single match with a common axis 36 which implies axial symmetry. In this case the X direction is arbitrary and so does not aid clone detection and is ignored. The number of X directions is set to 0. [0000] TABLE 3 Sample 31 32 33 34 35 Self Match 1 31 32 33 34 35 [0048] FIGS. 7 a and 7 b and table 4 illustrate N matches which implies N fold rotational symmetry. FIG. 7 a shows an initial coordinate frame and seven faces 41 to 47 . The rotation axis may be calculated as the common axis of rotation of the transforms and the angle of rotation as 360/N. FIG. 7 b shows an adjusted multiple coordinate frame and self mappings. The origin is improved by projecting onto the rotation axis, the Z direction is improved to be that of the rotation axis, as can be seen in FIG. 7 b . The N mappings are stored in the template, and each needs an X direction. The first X direction is recalculated to pass through the origin and be perpendicular to the Z direction, with the remaining freedom being less important. However, this may be chosen to make it point to a vertex or significant point. The other N-1 X directions are successive rotations of the first. [0000] TABLE 4 Sample 41 42 43 44 45 46 47 Self Match 1 41 42 43 44 45 46 47 x1 Self Match 2 42 43 44 45 46 41 47 x2 Self Match 3 43 44 45 46 41 42 47 x3 Self Match 4 44 45 46 41 42 43 47 x4 Self Match 5 45 46 41 42 43 44 47 x5 Self Match 6 46 41 42 43 44 45 47 x6 [0049] An error check is provided in that no match in the fast match step implies an error, as the template must match itself at least with the same choice of start face and edge. The faces from the template itself are omitted when gathering faces from the results, but the environment is searched for a ‘candidate list’ of face and edge pairs matching the start face and edge from the template according to the local fast properties stored. This is a new search of the whole environment, minus the actual start face and edge, looking for matches of start face and edge. For each face and edge pair remaining in the ‘candidate list’, the ‘fast matching procedure’ is performed resulting in a set of face mappings. The ‘exact geometry check’ is performed to find which of these mappings is geometrically correct and if an exact geometric match is found, then a clone is formed with the mapping returned from the fast match procedure and the coordinate frame and transform returned from the exact geometric check. [0050] If the template has Nfold symmetry, then only 1 of the N possible mappings will have been returned from the fast match procedure. This is a benefit of this approach as the N-1 remaining mappings may now be inferred from the 1 found mapping and the N self-mappings found within the template as part of the symmetry check. Each of these additional mappings also gives rise to an additional X direction and transform which can also be calculated. The faces of the found clone are removed from the candidate list. [0051] An exact geometric check is used in the algorithm to determine whether a candidate mapping from template faces to candidate faces is an exact geometric match, ignoring the boundary edges. A coordinate frame is formed from the mapped candidate faces using the same procedure as for the template on the corresponding mapped entities in the candidate. The transform from template to candidate can now be calculated from the coordinate frame of the candidate relative to that of the template. [0052] Each candidate face's surface geometry is compared to that of the corresponding template face with the transform applied. All surfaces must match. Note that this check does not include edges and so does not enforce exact match at the boundary, which is as required. If this test fails, then the candidate is rejected. [0053] The requirement from the high level algorithm, of the fast graph matching procedure, is that it rapidly determines whether a candidate start face and edge have a neighbourhood of faces that match to the template topologically and also according to a number of fast local property checks. The matching requirement at the boundary is less strict with the number of boundary regions required to match but not the number of boundary edges or their properties. The example of FIG. 8 and table 5 shows a sample S 1 , with faces F 1 , F 2 , F 3 , F 4 , F 5 and clone C 1 with faces F 6 , F 7 , F 8 , F 9 , F 10 . In this case, a match would be expected as there is a single boundary region in both the sample and the clone, despite the number of edges being different. [0000] TABLE 5 Sample F1 F2 F3 F4 F5 Clone F6 F7 F8 F9 F10 [0054] Successful matches may yield multiple mappings from the template faces to candidate faces. As each candidate element (face, edge, or loop) is encountered it is checked against the properties stored in the template graph at the build graph stage. [0055] As each candidate face is encountered it is added to a mapping that is built up incrementally as matching proceeds. [0056] A connected chain of non-boundary edges is referred to as an ‘internal segment’ and a connected chain of boundary edges is referred to as a ‘boundary segment’. An example is illustrated in FIG. 9 , showing internal segments 38 and external segments 39 . [0057] A deterministic matcher is used as the core graph matching algorithm. It can be used for cases where a unique path can be constructed through the template. This algorithm is seeded with a face of the template, and one of its edges, along with a similar candidate face/edge pair. The hypothesis being that the candidate face/edge pair are part of a successful match. The algorithm uses the edges to identify the adjacent faces, which form a new candidate mapping. These faces may also be added to the processing stack for further edge comparisons. The method then proceeds around the loop of the first face 50 , as shown in FIG. 10 , checking the edges and adding in the new faces 51 , 52 , 53 , 54 as appropriate. Internal faces (i.e. faces that are only connected to other template faces) should have a consistent number of edges. Therefore, as the method walks around the loops of the template and candidate faces, the loops should both return to their starting points consistently. If not, the candidate is deemed inconsistent and rejected. Once the loop of the face is complete, the algorithm proceeds to the next face in the stack. The starting edge is the one that was used to reach the face. This keeps the template and candidate walks consistent. [0058] Boundary faces add an extra complication to this algorithm, as the boundary segments, i.e. connected chain of edges at the boundary, are permitted to alter. In one embodiment, an example template in FIG. 11 and a potential candidate in FIG. 12 are expected to match. The complication comes because the boundary segment of face 60 in the template has one edge 61 , whilst the candidate 62 has five edges 63 at that point. Clearly, propagating around the loop would result in inconsistencies due to a differing number of edges. To avoid this issue, the deterministic matching algorithm stops walking around the loop when it reaches a boundary segment in the template. It then returns to its starting edge (the edge through which it propagated onto the face) and continues in the opposite direction. [0059] For many templates, where each face's internal edges are all connected, it is possible to reach them all in a deterministic manner and so the deterministic matching is sufficient. However, there are two situations where the internal edges are not all connected and require the algorithm to branch. The first is when a face has multiple loops (multiple loop branching) and the second is when there are multiple boundary segments (multiple boundary segment branching). For the example of multiple loop branching, the deterministic matching algorithm proceeds around the template and proceeds around the candidates by walking the loops and stepping onto the new faces. However, if a face has multiple loops, this algorithm needs to be able to step from one loop to the other. The complication here is that, from a topological viewpoint, it is not possible to know which edge in the second loop to step onto. This issue is illustrated in the example template in FIG. 13 and table 5 below. Starting from face 70 , deterministic matching can propagate in a consistent and repeatable manner for the first five faces 70 , 71 , 72 , 73 , 74 . However, face 75 has two loops, the second of which has four edges. Therefore, there are four potential starting edges for the next part of the graph. The matching algorithm has to test all four possibilities. Due to the rotational symmetry of the model, all of these possibilities will result in a successful mapping. Assuming a given start edge, the resulting four mappings are provided in the table below. [0000] TABLE 6 Template Mapping 1 Mapping 2 Mapping 3 Mapping 4 70 70 70 70 70 71 71 71 71 71 72 72 72 72 72 73 73 73 73 73 74 74 74 74 74 75 75 75 75 75 76 76 77 78 79 77 77 78 79 76 78 78 79 76 77 79 79 76 77 78 [0060] When used in the symmetry checking part of the algorithm, all four of the edges around face 70 are tested so giving sixteen acceptable topological mappings, then this is cut down to four by the exact geometric test to yield four mappings and imply four-fold symmetry. With this knowledge of the symmetry, the second use of this matching within the clone finding only needs to return one mapping and the other valid mappings are inferred as described above. Multiple loop branches are easily found as they are defined as any face in the template which has more than one loop. If a face with multiple loops is encountered, the matcher adds the “next” loop as a branch. The “next” loop is arbitrarily chosen as one of the unprocessed template loops, which is used as the next to compare. The ordering of the loop branches may be optimised to improve efficiency. [0061] In the case of multiple loop branching with dependency, there is a dependency between loops on the same face, so only one of these will be chosen as a branch after each deterministic match. The example of FIGS. 14 a to 14 c shows how the matching of the loops on the different faces can be treated independently, but the loops within each face must be processed in a dependent manner. The sample in FIG. 14 a has faces 80 , 81 and protrusions 82 , 83 . Two multiple loop faces on the main block, the top face 80 and front face 81 can be treated independently, so are processed as separate, independent branches. Within each branch, the start of the “next” loop could be any one of the twelve unprocessed faces, i.e. for the face 80 branch, the sides of protrusions 82 a , 82 b , 82 c as shown in FIG. 14 b and for the face 81 branch, the sides of the protrusions 83 a , 83 b , 83 c as shown in FIG. 14 c . As can be seen in FIGS. 15 a to 15 c , each of the faces 82 a results in a successful topological matching of that sub-graph, leaving the remaining eight candidate edges 82 b , 82 c for the loop after that and four candidate edges 82 c for the next with the number of mapping combinations multiplying at each stage. Similarly for protrusions 83 and candidate edges 83 a , 83 b , 83 c. [0062] This example is chosen with a great many equal edge lengths, in order to draw out the fact that the local-only property checks, such as edge length, can still yield a great many mappings on certain models. In practice, it is possible to remove this type of branching in many cases by adding further ‘semi local’ geometric checks. For example, the deterministic matching could determine nearest edges and/or vertices to link one loop to another, extending the walk rather than branching. Additionally, when a large number of combinations cannot be avoided, the mappings may be stored in a tree structure, which is more compact and can be geometrically checked in a more efficient hierarchical manner. Alternatively, some of the exact geometric checking may be performed within the graph matching, with a balance between cutting down the generated mappings versus adding computation time to the fast matching. The resulting performance of the algorithm is the driving factor in tuning this aspect of the method to a particular domain. [0063] FIGS. 16 a and 16 b and table 7 are examples of multiple boundary segment branching. In FIG. 16 a , boundary segments 96 of face 91 can be seen in an example illustrating a template where an additional sphere, face 95 , means that face 91 has two boundary segments. When the deterministic algorithm propagates onto face 91 from any of faces 90 , 92 or 94 , it will process the edges in loop order, and reverse loop order until it reaches a boundary segment. The method never propagates onto face 95 . Although the template only has one edge in each of the boundary segments, a successful candidate may have several edges. When comparing with candidate faces as shown in FIG. 16 b , the method needs to branch to discover a match for face 95 . The set of potential edges to check extends from the left hand side of sphere F to the right hand side of sphere H. The algorithm needs to test all five of these possibilities and should discover three topologically correct matches. There is no need to test the edges 97 , 98 immediately before F and after H, as boundary segments are expected to consist of at least one edge. Three topologically correct mappings are output as indicated in table 7 below. [0000] TABLE 7 Template Mapping 1 Mapping 2 Mapping 3 90 A A A 91 B B B 92 C C C 93 D D D 94 E E E 95 F G H [0064] Multiple boundary segment branch points can be dependent, as there could be several sub-graphs originating from the same face-loop. The location of one of these is dependent on the previous one. For example, the template shown in FIG. 17 has such a boundary face (face 101 ) with two remaining internal segments connected to it at the boundary, still to be matched. After successfully matching faces 100 to 104 , an initial attempt is made to search for the internal segment connecting to faces 105 , 106 and 107 , as the potential candidates for the internal segment connecting to 113 , 114 and 115 are dependent on the location of that first internal segment. The algorithm needs to repeatedly call the deterministic matching algorithm with the various candidate starting edges for the next internal segment. Once the deterministic method has found a successful match for the sub-graph, i.e. faces 105 , 106 , 107 and 108 ), it then adds the next internal segment, connecting to faces 113 , 114 , 115 and 116 , as another branch. During the matching of faces 105 , 106 , 107 and 108 , it will also encounter another branch at face 108 and so on. [0065] When a branch is reached, the candidate edges are collated, and then explored. For multiple loop branches, the function can stop once a correct match for the branch has been found, as the mappings that result from alternative candidates can be inferred. As there may be multiple successful candidates, all these different mappings must be compiled. For the independent branches, the resulting successful mappings need to be merged, which involves producing a complete set that includes every combination from each sub-branch. To see this, consider the example template of FIG. 18b with faces 121 , 122 , 123 , 124 , 125 , 126 , 127 . Spherical faces 125 and 126 result in boundary branches, which are independent as they occur on different faces. When this model is being matched to the candidate shown in FIG. 18 a, as indicated in table 8, each of the branch points finds two successful matches. The branch from face 121 produces two mappings, where face 126 maps to either H or I. Likewise, the branch from face 124 produces two mappings for face 125 , mapping to either face F or G. Merging the options from these independent branches involves forming all combinations of the options in each branch. The two options in the branches result in 2×2=4 possible combinations for the mappings of faces 125 and 126 (HF, HG, IF, IG). All four of the mappings provide the same face pairs for the first five faces. [0000] TABLE 8 Branch 1 Branch 2 Template Mapping 1 Mapping 2 Mapping 1 Mapping 2 127 A A A A 121 B B B B 122 C C C C 123 D D D D 124 E E E E 125 N/A N/A F G 126 H I N/A N/A [0066] A further complication concerns features that result in cyclic graphs, as illustrated in FIGS. 19 a , 19 b and 19 c . The example template of FIG. 19a contains a potential branch face 130 , as the template has two distinct internal segments 131 , 132 , segment 131 indicated by a solid line and segment 132 indicated by a dotted line. However, the right-hand component 133 of the feature enables a different route to the second segment 132 , so this model can be matched by purely deterministic means. Therefore, when exploring branches, it is necessary to verify that the internal segment being sought has not already been found. In the example of FIG. 19b , a template is shown with two sub-graphs. The branch face 134 has three separate internal segments segment 135 shown by a solid line and segments 136 , 137 shown by a dotted line, the three segments indicating two dependent branches. However, exploration of the first branch deterministically discovers the third internal segment 137 . In the example of FIG. 19c is shown another template with two branch faces 138 . Each sub-graph provides two independent branches. However, exploration of the first branch will discover the second branch deterministically. [0067] The method is fast to both find clones and also reject non-clones for a number of reasons. Combining a deterministic walk with branching means the potential search tree is minimal. The use of local properties further reduces the actual search tree drastically. The graph matching is exhausted before any geometric tests are performed, which may be expensive in terms of CPU time and hence overall time taken. Analysis of the input allows symmetric clones to be inferred rather than explicitly found, reducing the search space. Judicious choice of start faces and edges reduces the number of matches that are attempted. The topology and geometry split allows diagnostic output in cases where clones might be expected but are not returned due to partial topology matches or partial geometry matches. The topology and geometry split allows a number of additional features to be incorporated, as explained in more detail below. The return of mapping and coordinate frame information means that the output is readily usable in geometric pattern identification. The method also produces consistent coordinate frames and transforms which are useful for downstream applications. The symmetry detection, as well as speeding up the processing, gives rise to a superior coordinate frame in rotationally symmetric cases along with all the mappings which, again, will likely be useful downstream. [0068] There are numerous extensions and expansions that may be used with the method disclosed. The scope may be increased to include templates comprising multiple connected faces sets. The choice of start face/edge may be tuned for each template, for example trying to choose the start/edge pair that maximises the portion of the graph that can be visited deterministically. This increases the chance of rejecting a candidate without branching. The choice of start face/edge may be tuned for a particular environment, taking into account any knowledge of likely frequency of different properties for a particular domain or actually pre-scanning the presented environment to ascertain this. This is beneficial when the same environment is searched to many different templates. Some of the boundary, or all of the boundary, may be important, so flexibility can be added to require an exact match on some or all of the boundary edges. [0069] Some exact geometric checks may be replaced by logical checks. For example internal treatment faces, such as blends or chamfers, can be checked by type and parameters rather than geometry, allowing for more tolerant matches as well as allowing variations of the parameters (blend radii for example) in these areas. Geometry checking can be made tolerant to allow for import from different systems. The topological and geometric division of the method allows for possible recognition of similar topological clones with some degree of geometric variation, for example: overall size (scale) or particular parametric variations in a family of features. Adjustment of the topology and geometry checking allows for symmetric or mirrored features to be identified. A partial matcher may be implemented that allows a threshold of matching to be required and the system indicates which portion of the template matches. There may be further special cases for the choice of Z axis direction in the non-symmetric cases. [0070] A particularly helpful feature for product design allows inverted matches, so that a template of a part may be used for finding the correct corresponding part, such as a peg for a particular hole, or a feature on a mould that matches with features on the part. The method may be utilised on the fly, within any application that can make use of similarity. In this context, the clones do not have to be permanently labelled, but are discovered as needed and may vary and evolve as the model is progressively built. Quite simply, the disclosed method provides a powerful selection tool, being particularly effective at finding samples which are substantially, but not totally topologically equal because the method is able to reject unsuitable samples efficiently. [0071] Of course, those of skill in the art will recognize that, unless specifically indicated or required by the sequence of operations, certain steps in the processes described above may be omitted, performed concurrently or sequentially, or performed in a different order. [0072] Those skilled in the art will recognize that, for simplicity and clarity, the full structure and operation of all data processing systems suitable for use with the present disclosure is not being depicted or described herein. Instead, only so much of a data processing system as is unique to the present disclosure or necessary for an understanding of the present disclosure is depicted and described. The remainder of the construction and operation of data processing system 1 may conform to any of the various current implementations and practices known in the art. [0073] It is important to note that while the disclosure includes a description in the context of a fully functional system, those skilled in the art will appreciate that at least portions of the mechanism of the present disclosure are capable of being distributed in the form of instructions contained within a machine-usable, computer-usable, or computer-readable medium in any of a variety of forms, and that the present disclosure applies equally regardless of the particular type of instruction or signal bearing medium or storage medium utilized to actually carry out the distribution. Examples of machine usable/readable or computer usable/readable mediums include: nonvolatile, hard-coded type mediums such as read only memories (ROMs) or erasable, electrically programmable read only memories (EEPROMs), and user-recordable type mediums such as floppy disks, hard disk drives and compact disk read only memories (CD-ROMs) or digital versatile disks (DVDs). [0074] Although an exemplary embodiment of the present disclosure has been described in detail, those skilled in the art will understand that various changes, substitutions, variations, and improvements disclosed herein may be made without departing from the spirit and scope of the disclosure in its broadest form. [0075] None of the description in the present application should be read as implying that any particular element, step, or function is an essential element which must be included in the claim scope: the scope of patented subject matter is defined only by the allowed claims. Moreover, none of these claims are intended to invoke 35 USC §112(f) unless the exact words “means for” are followed by a participle.

Methods for identifying geometric clones in a modelling system, or simulating modifications to construction of a multi-part product and corresponding data processing systems and computer readable media. A method includes choosing a template of a geometric form and generating and storing a map of the template, identifying a candidate geometric form in the system and exploring the identified candidate geometric form from a start point until returning to the start point or reaching a branch. The method includes generating a map of the explored candidate geometric form, comparing the map of the explored candidate geometric form with the map of the template and labelling the candidate geometric form as a clone if it matches a predetermined portion of the template.

FIELD OF THE INVENTION This invention relates to a system or method of checking information relating to the connections of a multistage switch. More particularly, the invention relates to a method of checking the validity of connection information that has been stored in the memory of a multistage matrix switch. Description of the Related Art BACKGROUND OF THE INVENTION The art disclosed in the specification of Japanese Patent Kokai Publication JP-A-8-320835 is an example of the related prior art. Specifically, FIG. 7 illustrates a system of checking information relating to the connections of a 3-stage switch having a switch size of M×N in which M incoming lines and N outgoing lines are selectively connected, where M and N represent natural numbers. As shown in FIG. 7, the switch section of this 3-stage switch includes P discrete switches 11, . . . , 1K, . . . , 1P (where P=M/m) of switch size m×r each selectively connecting m incoming lines and r outgoing lines (where m, r are natural numbers and m≦M holds) and belonging to a primary switch group 1; R discrete switches 21, . . . , 2A, . . . , 2R each selectively connecting p incoming lines and q outgoing lines and belonging to a secondary switch group 2; Q discrete switches 31, . . . , 3K, . . . , 3Q (where Q=N/n) each selectively connecting r incoming lines and n outgoing lines and belonging to a tertiary switch group 3; and a main controller 4 for controlling connections through the primary, secondary and tertiary switches 1, 2 and 3, respectively. The controller 4 has a memory 41 for storing information relating to the connections of each discrete switch. The discrete switches belonging to each discrete switch group have a switch unit for connecting one of a plurality of input terminals and one of a plurality of output terminals, and a switch controller for connecting this switch unit with the memory 41. By way of example, as shown in FIG. 8, a primary switch 1K which belongs to the primary switch group 1 incorporates a switch unit 1K1 and a switch controller 1K2. Similarly, secondary switches 2A, 2B which belong to the secondary switch group 2 have switch units 2A1, 2B1, respectively, and switch controllers 2A2, 2B2, respectively. Likewise, tertiary switches 3H, 3K which belong to the tertiary switch group 3 have switch units 3H1, 3K1, respectively, and switch controllers 3H2, 3K2, respectively. The switch controller 1K2 of the primary switch 1K is connected to the main controller 4 by a control line 62. The switch controllers of the other discrete switches are connected to he main controller by control lines in a similar manner. The manner in which input and output terminals of each discrete switch are connected will be described with reference to FIG. 9. An ath (1≦a≦r) output terminal 1Kao of the Kth (1≦K ≦P) switch 1K of primary switch group 1 is connected to a kth (1≦k≦p) input terminal 2Aki of the Ath (1≦A≦R) switch 2A of secondary switch group 2 by a signal line 51. An hth (1≦h≦q) output terminal 2Aho of this switch 2A is connected to an ath (1≦a≦r) input terminal 3Hai of the Hth (1≦H≦Q) switch 3H of tertiary switch group 3 by a signal line 53. Further, a kth (1≦k ≦p) output terminal 2Ako of the switch 2A is connected to an ath input terminal 3Kai of the Kth (1≦K≦Q) switch 3K of tertiary switch group 3 by a signal line 54. Further, a bth (1≦b ≦r) output terminal 1Kbo of the switch 1K is connected to a kth input terminal 2Bki of the Bth (1≦B≦R) switch 2B of secondary switch group 2 by a signal line 52. Further, an hth output terminal 2Bho of the Bth switch 2B of secondary group 2 is connected to a bth input terminal 3Hbi of the switch 3H by a signal line 55, and a kth output terminal 2Bko of the switch 2B is connected to a bth input terminal 3Kbi of the switch 3K by a signal line 56. Accordingly, in the arrangement illustrated in FIG. 7, the output terminals 1˜r of the first switch 11 in primary switch group 1 are connected to the first input terminals (1) of the 1st˜rth switches 21˜2R, respectively, of secondary switch group 2. Similarly, the output terminals 1˜q of the first switch 21 in secondary switch group 2 are connected to the first input terminals (1) of the switches 31˜3Q, respectively, of tertiary switch group 3. Thus, the output terminals of each discrete switch are cross-connected to the input terminals of the switches of the next stage. A method of connecting paths in a 3-stage switch having such a construction will now be described with reference to FIG. 9. In a case where there is a request to connect an input terminal X (where X≦M) of the overall 3-stage switch and an output terminal Y (where Y≦N), the main controller 4 computes that the input terminal X corresponds to an input terminal α of the Kth switch 1K of primary switch group 1 and that the output terminal Y corresponds to an output terminal β of the Hth switch 3H of tertiary switch group 3. By using the memory 41, the status of use of output terminal β of switch 3H is detected and the following processing is executed based upon the results of detection: (1) In a case where the output terminal β of switch 3H is currently in use, an input terminal of the 3-stage switch that will make the connection to β (or Y) is retrieved. If the retrieved input terminal is X, the status is made "already connected" because the path for which connection was requested has already been connected. If the retrieved input terminal is different from X, then the status is made "connection impossible". (2) In a case where the output terminal β of switch 3H is not in use, the main controller 4 retrieves from the memory 41 the states of use of output terminals 1˜r of switch 1K of primary switch group 1 successively starting from the first output terminal. For example, if 1st˜(a-1)th output terminals of switch 1K are in use and the ath output terminal 1Kao is not use, the main controller 4 next retrieves the status of use of output terminal 2Aho of switch 2A of secondary switch group 2 connected to switch 3H of tertiary switch group 3 to which output terminal β belongs. If this output terminal 2Aho is not in use, a path connecting the input terminal X and output terminal Y of the 3-stage switch can be acquired by connecting input terminal 1Kαi and output terminal 1Kao of switch 1K of primary switch group 1, input terminal 2Aki and output terminal 2Aao of switch 2A of second switch group 2, and input terminal 3Hai and output terminal 3Hβo of switch 3H of tertiary switch group 3. Accordingly, instructions for connecting the input and output terminals of the discrete switches along the retrieved path are transmitted to the switch controllers of the discrete switches. In a case where each discrete switch executes the connection of the requested path to connect the input and output terminals normally, the status "normal end" is sent back to the main controller 4. In a case where the path has been connected as requested, the main controller 4 saves the connection information (the switch numbers of the discrete switches, the input terminal numbers and the output terminal numbers of the discrete switches), which has been set for each of the discrete switches, in the memory 41. In a case where the output terminal 2Aho of switch 2A is in use, on the other hand, the main controller 4 retrieves the status of use of the bth (a<b) output terminal 1Kbo of switch 1K. If this output terminal is not in use, the main controller next retrieves the status of use of the hth output terminal 2Bho of switch 2B connected to switch 3H. The main controller 4 repeats the operation described above until a usable output terminal of a primary switch and output terminal of a secondary switch are found. A method of checking the connection information of such a multistage switch according to the prior art is as follows: Before generating a required connection instruction for each discrete switch, a check is made in regard to the discrete switch connection information that has been stored in the memory 41. Specifically, the fact that the discrete switches constructing the multiple stages are permanently connected in accordance with a prescribed rule is utilized to check, for each connection path, whether the output terminal number of a switch of a cth (c≦S-1) stage of the multistage switch and the input terminal number of a switch of the (c+1)th stage are capable of being logically connected, and to check whether the input terminal number and output terminal number of each discrete switch that have been stored in the memory unit as well as the switch number in the multistage switch fall within appropriate limits, thereby checking the logical normality of the multistage switch connection information that has been stored in the memory. If the result of the logical check of the connection information is "normal", then, in regard to a path X-Y for which connection has been requested anew, the main controller 4 retrieves output terminals, which are not in use, based upon the connection information in memory 41 and generates a connection instruction each discrete switch is required to execute. Consequently, the logical validity of the connection information is assured. Furthermore, in a case where the result of the connection from the switch controller of each discrete switch is indicative of "normal end", the main controller 41 verifies that the path for which connection is requested has been set reliably for each discrete switch and adds the information indicative of the input and output terminals for which the path has been set onto the connection information in the memory 41. SUMMARY OF THE DISCLOSURE In the course of investigations toward the present invention, various problems have been encountered. Namely the above-described conventional method of checking multistage-switch connection information that has been stored in the memory involves a number of problems, which will now be set forth. (1) The first problem is that if a request for connecting input and output terminals of the multistage switch is issued under conditions in which the connection information of the overall multistage switch stored in the memory unit of the main controller does not coincide with the connection states set for the switch units of each of the discrete switches, there will be cases where a path that has already been set for each discrete switch will be severed. The reason for this is that the main controller, in response to a request to connect input and output terminals of the multistage switch, retrieves a connectable path based upon connection information in the memory that does not match connection paths actually set for the switch units of each of the discrete switches. In certain cases, therefore, there are instances where the main controller newly sets another path for an output terminal that is already being used. (2) The second problem regards a case where the control lines connecting the main controller with the controllers of the discrete switches are severed or a case where the controllers of the discrete switches are reset. In order to match the connection information of the main controller with the connection states of the discrete switches, the connection information in the memory of the main controller is overwritten on each discrete switch after communication between the main controller and the switch controllers is restored. However, if the overwriting of the connection information is initiated under conditions in which the connection information of the multistage switch that has been stored in the memory does not match the connection paths that have been set for the switch units of the discrete switches, there will in some cases be instances where a path that has already been set for a discrete switch will be severed. The reason for this is that since connection instructions different from the connection states of the discrete switches are overwritten on the discrete switches, there will in some cases be instances where a path different from an already established path is set. Accordingly, it is an object of the present invention to provide a system or method of checking connection information of a multistage switch in which multistage-switch connection information that has been set in a memory is compared with connection paths set for the switch units of discrete switches, and inadvertent severance of a connection path, which has been set for the discrete switches, caused by non-agreement between the connection information and connection path is prevented. Further objects of the present invention will become apparent in the entire disclosure. According to one aspect of the present invention, there is provided a system of checking connection information of a multistage switch having an M×N switch size selectively connecting M incoming lines and N outgoing lines (where M, N are natural numbers) and having S stages (where S is a natural number) of discrete switches, wherein the discrete switches are permanently cross-connected in accordance with a prescribed rule, said system comprising: means for retrieving connection information of the overall multistage switch that has been stored in a memory storing connection information relating to each discrete switch and to the overall multistage switch, as well as connection states of switch units of each of the discrete switches; means for generating connection information of the overall switch from results of retrieval by utilizing the fact that an output terminal of a switch in a cth (where c≦S-1) stage of the multistage switch is to be logically connected to an input terminal of a switch in a (c+1)th stage; and means for comparing the generated connection information of the overall multistage switch and connection information that has been stored in the memory in advance; wherein a connection path that has been set for each discrete switch is prevented from being severed accidentally. According to another aspect of the present invention, the foregoing object is attained by providing a system of checking connection information of a multistage switch, wherein the multistage switch generally includes: a switch section, a memory for storing connection information and a main controller. The switch section has an M×N switch size selectively connecting M incoming lines and N outgoing lines (where M, N are natural numbers) and consisting of S stages (where S is a natural number) of discrete switches, wherein the discrete switches are permanently cross-connected in accordance with a prescribed rule. The memory stores connection information relating to each discrete switch and to the multistage switch. The main controller, in response to a request to the multistage switch for connection of a path connecting an input terminal number a and an output terminal b (where a≦M, b≦N), retrieves, based upon the connection information that has been stored in the memory, states of use of input terminal numbers and output terminal numbers of each of the discrete switches and a connectable connection path through the multistage switch, transmits connection instructions to switch controllers of respective ones of the discrete switches based upon results of retrieval, receives results of execution of path connection from the switch controllers of the discrete switches, and updates the connection information, which has been stored in the memory, based upon the results of execution received. The multistage switch of switch size M×N is composed of discrete switches each having a switch size of mS×nS (where mS≦M, nS≦N) selectively connecting mS incoming lines and nS outgoing lines (where mS, nS are natural numbers). Each discrete switch includes a switch unit of the switch size mS×nS, and a switch controller for managing connection information of the switch unit, receiving a connection instruction from the main controller and transmitting results of connection to the main controller via a control line connected to the main controller. The system is constructed as follows: the switch controller of each discrete switch retrieves an input terminal number mS of an input terminal that is connected to an output terminal number nS of the switch unit, retrieves input terminal numbers of connected input terminals with regard to all output terminals of the switch unit and adopts results of retrieval as the connection information of the discrete switch; The main controller reads the connection states of each of the discrete switches constituting the M×N multistage switch out of the switch controllers of all of the discrete switches, and retrieves, based upon the connection states of each of the discrete switches, the input terminal number a of the input terminal of the multistage switch that is connected to the output terminal number b of the output terminal of the multistage switch, as well as a connection path through the multistage switch, by utilizing the fact that an output terminal of a switch in a cth (where c≦S-1) stage is capable of being logically connected to an input terminal of a switch in a (c+1)th stage; The main controller repeats processing for retrieval of input terminal numbers of connected input terminals and connection paths with regard to all output terminals of the multistage switch, and generates connection information relating to the overall multistage switch based upon results of retrieval; and The main controller compares the connection information of the overall multistage switch retrieved and generated based upon the connection state of each discrete switch with connection information of the overall multistage switch stored in the memory in advance. PREFERRED EMBODIMENTS The principles and operation of the present invention constructed as set forth above will now be described. Connection information relating to an S-stage (where S is a natural number) multistage switch is stored in a memory. The switch controller of each discrete switch of the multistage switch performs the operation set forth below: (1) in a case where a connectable path is retrieved, based upon connection information relating to each discrete switch that has been stored in the memory, in response to a request to connect input and output terminals of the multistage switch, and (2) in a case where communication failure between a main controller and a switch controller of a discrete switch is restored and the connection information is overwritten onto each discrete switch for the purpose of matching the connection information in the memory and connection paths through the discrete switches. The switch controller of each discrete switch retrieves input terminal numbers of input terminals connected to all output terminals of the switch unit and adopts the results of retrieval as the status of connection of the discrete switch. The main controller of the multistage switch reads the connection states of each of the discrete switches constituting the multistage switch out of the switch controllers of all of the discrete switches and retrieves, based upon the connection information of each of the discrete switches, the input terminal number of an input terminal of the multistage switch that is connected to the output terminal number of an output terminal of the multistage switch by utilizing the fact that an output terminal number of a switch in a cth (where c≦S-1) stage is capable of being logically connected to an input terminal number of a switch in a (c+1)th stage. The main controller repeats processing for retrieval of input terminal numbers of connected input terminals and connection paths with regard to all output terminals of the multistage switch and generates connection information relating to the overall multistage switch based upon the results of retrieval. The main controller compares the connection information of the overall multistage switch retrieved and generated based upon the connection state of each discrete switch with connection information of the overall multistage switch stored in the memory beforehand. As a result, agreement between the status of the connection of each discrete switch and the connection information of the overall multistage switch that has been stored in the memory is verified. In the aforesaid case (1), therefore, a connectable path is retrieved based upon the connection information in the memory in response to a request to connect input and output terminals of the multistage switch and the severance of an already established connection path, which may be caused by establishing a new path to an output terminal that is already being used, can be prevented. In the aforesaid case (2), it is possible to prevent connection paths, which have already been established for the discrete switches, from being severed owing to overwriting of connection information, which does not agree with the connection states established for the discrete switches, from the memory. Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram useful in describing the connections of signal lines in a multistage switch for practicing the present invention; FIG. 2 is a diagram useful in describing the details of construction of a multistage switch for practicing the present invention; FIG. 3 is a diagram useful in describing the details of construction of a multistage switch for practicing the present invention; FIG. 4 is a diagram illustrating the connections of signal lines in a multistage switch according to an embodiment of the present invention; FIG. 5 is a diagram useful in describing the connections of control lines in a multistage switch according to this embodiment of the present invention; FIG. 6 is a diagram illustrating the construction of this embodiment of the present invention; FIG. 7 is a diagram useful in describing the connections of signal lines in a multistage switch according to the system of prior art; FIG. 8 is a diagram useful in describing the connections of control lines in a multistage switch according to the system of prior art; and FIG. 9 is a diagram illustrating the details of the conventional system. DESCRIPTION OF THE PREFERRED EMBODIMENT A mode for practicing the present invention will be described with reference to the accompanying drawings. (1) Configuration A multistage switch according to this mode of practicing the present invention has a switch size of N×M for selectively connecting M incoming lines and N outgoing lines, where M and N represent natural numbers. Each discrete switch group of the multistage switch has a plurality of switch units, and each of the discrete switches has a plurality of input terminals and a plurality of output terminals. FIG. 1 is a diagram showing an example of the configuration of this mode of practicing the invention. Specifically, FIG. 1 illustrates a 5-stage switch as an example of multistage switch. As shown in FIG. 1, the 5-stage switch includes P discrete switches (where P=M/m) of switch size m×r each selectively connecting m incoming lines and r outgoing lines (where m, r are natural numbers and m≦M holds) and belonging to a primary switch group 1; R switch groups each selectively connecting p incoming lines and q outgoing lines and belonging to a secondary switch group 2; Q discrete switches (where Q=N/n) each selectively connecting r incoming lines and n outgoing lines and belonging to a tertiary switch group 3; and a main controller 4 for controlling connections through the primary, secondary and tertiary switches 1, 2 and 3. As shown in FIG. 2, a main controller 4 has a memory 41 for storing the states of the connections of the discrete switches. The memory 41 is divided into an area 411 for storing connection information relating to the overall multistage switch, and an area 412 for storing the states of connections read out of the switch units of the discrete switches. Each individual switch group of switch groups 21˜2R belonging to the secondary switch group 2 is constructed as a 3-stage switch. More specifically, each of the switch groups 21˜2R is composed of T discrete switches (where T=p/d) each selectively connecting d incoming lines and s outgoing lines (where d, s are natural numbers and s≦p holds) and corresponding to a first stage of the 3-stage switch; S discrete switches each selectively connecting t incoming lines and u outgoing lines (where t, u are natural numbers) and corresponding to a second stage of the 3-stage switch; and U discrete switches (where U=q/e) each selectively connecting s incoming lines and e outgoing lines (where s, e are natural numbers and e≦q holds) and corresponding to a third stage of the 3-stage switch. Accordingly, here the multistage switch having the switch size of M×N is a switch composed of five stages in all. A switch thus can be constructed from three of more stages by replacing a portion constructed as a discrete switch by a switch group obtained by dividing a plurality of discrete switches into three stages. The discrete switches belonging to each of the discrete switch groups have a switch unit for connecting one of a plurality of input terminals and one of a plurality of output terminals, and a switch controller for controlling the switch unit. By way of example, as shown in FIG. 2, a switch 1K belongs to the primary switch group 1 and incorporates a switch unit 1K1 and a switch controller 1K2. Similarly, a switch 3H belongs to the tertiary switch group 3 and incorporates a switch unit 3H1 and a switch controller 3H2. The secondary switch group 2 has switches 2A11, 2A1C, 2A1T corresponding to a first stage of switch group 2A, switches 2A21, 2A2B, 2A2S corresponding to a second stage of switch group 2A and switches 2A31, 2A3F, 2A3U corresponding to a third stage of switch group 2A. The switches 2A11, 2A1C, 2A1T have switch units 2A111, 2A1C1, 2A1T1, respectively, and switch controllers 2A112, 2A1C2, 2A1T2, respectively; the switches 2A21, 2A2B, 2A2S have switch units 2A211, 2A2B1, 2A2S1, respectively, and switch controllers 2A212, 2A2B2, 2A2S2, respectively; and the switches 2A31, 2A3F, 2A3U have switch units 2A311, 2A3F1, 2A3U1, respectively, and switch controllers 2A312, 2A3F2, 2A3U2, respectively. The switch controller 1K2 of switch 1K is connected to the main controller 4 by a control line 62. The switch controllers of the other discrete switches are connected to the main controller 4 by control lines in a similar manner. The manner in which input and output terminals of each discrete switch are connected will be described with reference to FIG. 2. An ath (1≦a≦r) output terminal 1Kao of the Kth (1≦K≦P) switch 1K of primary switch group 1 is connected to a kth (1≦k≦p) input terminal 2Aki of the Ath (1≦A≦R) switch group 2A of secondary switch group 2 by a signal line 51. An hth (1≦h≦q) output terminal 2Aho of this switch group 2A is connected to an ath (1≦a≦r) input terminal 3Hai of the hth (1≦H≦Q) switch 3H of tertiary switch group 3 by a signal line 53. In a case where reference is made to FIG. 1, the output terminals 1˜r of the 1st switch 11 of the primary switch group 1 are connected to the first input terminals of the 1st˜rth switch groups 21˜2R, respectively, of the secondary switch group 2. Similarly, the output terminals 1˜q of the first switch group 21 in secondary switch group 2 are connected to the first input terminals of the switches 31˜3Q, respectively, of tertiary switch group 3. Thus, the output terminals of each discrete switch are cross-connected to the input terminals of the switches of the next stage. FIG. 3 is a diagram schematically showing an example of connections in a switch group contained in the secondary switch group 2 of this embodiment. Reference will be had to FIG. 3 to describe the connections in a given switch group within the secondary switch group. A bth (1≦b≦s) output terminal 2A1Cbo of a Cth (1≦C≦T) switch 2A1C of the first stage in the Ath switch group 2A of the secondary switch group 2 is connected by a signal line 57 to a cth (1≦c≦t) input terminal 2A2Bci of a Bth (1≦B≦S) switch 2A2B of the second stage, and an fth (1≦f≦u) output terminal 2A2Bfo of this switch 2A2B is connected by a signal line 58 to a bth input terminal 2A3Fbi of an Fth (1≦F≦U) switch 2A3F of the third stage. With reference to the first switch group 21 of the secondary switch group shown in FIG. 1, output terminals 1˜s of the first switch 2111 of the first stage of switch group 21 are connected to the first input terminals of 1st˜sth switches 2121˜212S, respectively, of the second stage. Similarly, output terminals 1˜u of the first switch 2121 of the second stage of switch group 21 are connected to the first input terminals of switches 2131˜213U, respectively, of the third stage. Thus, the output terminals of each discrete switch are cross-connected to the input terminals of the switches of the next stage even in the 3-stage switch within each discrete switch group belonging to the secondary switch group 2. (2) Operation The operation of this embodiment of the present invention will now be described in detail with reference to the drawings. A case will be described in which there is a request to connect an input terminal X (where X≦M) and an output terminal Y (where Y≦N) of the overall multistage switch. A method of connecting a path will be described first. The main controller 4 receives a connection request and responds by computing that the input terminal X corresponds to an input terminal α of the Kth switch 1K of primary switch group 1 and that output terminal Y corresponds to an output terminal β of the Hth switch 3H of tertiary switch group 3. Next, the main controller 4 retrieves the status of use of output terminal β of switch 3H from the area 411 of memory 41 and executes the following processing based upon the results of retrieval: (1) In a case where the output terminal β of switch 3H is currently in use, an input terminal of the multistage switch that will make the connection to β (or Y) is retrieved. If the retrieved input terminal is X, the status is made "already connected" because the path for which connection was requested has already been connected. If the retrieved input terminal is different from X, then the status is made "connection impossible". (2) In a case where the output terminal β of switch 3H is not in use, the main controller 4 retrieves from the area 411 of memory 41 the states of use of output terminals 1˜r of switch 1K of primary switch group 1 successively starting from the first output terminal. For example, if 1st (a-1)th output terminals of switch 1K are in use and the ath output terminal 1Kao is not in use, the main controller 4 next retrieves the status of use of the hth output terminal 2Aho of switch group 2A of secondary switch group 2 connected to switch 3H of tertiary switch group 3 to which output terminal β belongs. If the output terminal 2Aho is in use, the main controller 4 retrieves the status of use of the bth (a<b) output terminal 1Kbo of switch 1K. If the output terminal 1Kbo is not in use, the main controller 4 next retrieves the status of use of the hth output terminal 2Bho of switch group 2B connected to switch 3H. The main controller 4 continues executing the above-described processing until a usable output terminal of a primary switch and a usable output terminal of a secondary switch are found. If the output terminal 2Aho is not in use, the main controller 4 next retrieves a path capable of being set within the switch group 2A. In FIG. 3 the main controller 4 retrieves the states of use of 1st˜sth output terminals of the Cth switch 2A1C of the first stage of switch group 2A to which the input terminal 2Aki belongs. For example, if 1st˜(b-1)th output terminals of switch 2A1C are in use and the bth output terminal 2A1Cbo is not in use, the main controller 4 next retrieves the status of use of the fth output terminal 2A2Bfo of switch group of the second stage connected to switch 2A3F of the third stage to which output terminal 2Aho belongs. If the output terminal 2A2Bfo is in use, the main controller 4 retrieves the status of use of the (b+1)th output terminal 2A1C(b+1)o of switch 2A1C. If the output terminal 2A1C(b+1)o is not in use, the main controller 4 next retrieves the status of use of the fth output terminal 2A(B+1)fo of switch 2A2(B+1) of the second stage connected to switch 2A3F of the third stage to which the output terminal 2Aho belongs. The main controller 4 continues executing the above-described processing until usable output terminals of first and second stages are found. If the output terminal 2A2Bfo is not in use, on the other hand, the main controller 4 connects the input terminal 1Kαi and the output terminal 1Kao of switch 1K in primary switch group 1; connects the input terminal 2Aki and the output terminal 2A1Cbo of switch 2A1C of the first stage of switch group 2A in the secondary switch group 2; connects the input terminal 2A2Bci and the output terminal 2A2Bfo of switch 2A2B of the second stage of switch group 2A; connects the input terminal 2A3Fbi and the output terminal 2Aho of switch 2A3F of the third stage of switch group 2A; and connects the input terminal 3Hai and the output terminal 3H βo of switch 3H in tertiary switch group 3. As a result, a path connecting the input terminal X and the output terminal Y of the multistage switch can be acquired. Accordingly, instructions for connecting the above-mentioned input and output terminals are transmitted to the switch controllers of the discrete switches in each of the stages. More specifically, the main controller 4 transmits an instruction for connecting input terminal 1Kαi and output terminal 1Kao to the switch controller 1K2 of switch 1K; transmits an instruction for connecting input terminal 2Aki and output terminal 2A1Cbo to the switch controller 2A1C2 of switch 2A1C; transmits an instruction for connecting input terminal 2A2Bci and output terminal 2A2Bfo to the switch controller 2A2B2 of switch 2A2B; transmits an instruction for connecting input terminal 2A3Fbi and output terminal 2Aho to the switch controller 2A3F2 of switch 2A3F; and transmits an instruction for connecting input terminal 3Hai and output terminal 3Haα to the switch controller 3H2 of switch 3H. If each discrete switch executes path connection in accordance with the connection instruction received from the main controller 4 and connects the input and output terminals normally, then each discrete switch sends a signal indicative of "normal end" back to the main controller 4. Upon receiving the signals indicative of "normal end", the main controller 4 stores the switch numbers of the aforesaid five switches, as well as the input and output terminal numbers of these discrete switches, in the area 411 of the memory 41 as connection information relating to the connection between terminals X and Y of the multistage switch. If a control line connecting the main controller 4 and the switch controller of a discrete switch is severed or if the switch controller of a discrete switch is reset, then, in order to make the connection information that has been stored in the area 411 of memory 41 of the main controller 4 agree with the connection states of the discrete switches, the main controller 4 overwrites the connection information of area 411 of memory 41 onto the switch controllers of the discrete switches after communication between the main controller 4 and the switch controller of the discrete switch is restored. The switch controller of a discrete switch that has received an overwrite connection instruction from the main controller 4 changes the connection status of the switch unit in accordance with the connection instruction. In accordance with this mode of practicing the present invention, it is so arranged that when a request has been issued to connect input and output terminals of the overall multistage switch, agreement between the connection information that has been stored in the memory and the states of connections of the switch units of all discrete switches is verified (i) before execution of processing for retrieving a path capable of being established by the switch units of the discrete switches constituting the multistage switch and (ii) before the information that has been stored in the memory is overwritten to the switch units of the discrete switches. By way of example, operation will be described (a) in a case where a request to connect input terminal X and output terminal Y has been issued, under conditions in which only a path connecting input terminal X and output terminal Y exists in the multistage switch having the switch size of M×N in FIGS. 1 through 3 or (b) in a case where communication failure between the main controller 4 and a switch controller of a discrete switch constituting the multistage switch is restored and the connection information in area 411 of memory 41 is overwritten onto the switch units of the discrete switches. Before retrieving the path connecting input terminal X and output terminal Y, or before transmitting overwrite connection instructions that are in accordance with the connection information in memory 411 of memory 41 to the switch controllers of the discrete switches, the main controller 4 sends the switch controller of the 1st switch of the primary switch group an instruction for retrieving the input terminal numbers of input terminals to which the 1st˜rth output terminals of switch are connected, and for sending back the retrieved results. The main controller 4 then stores the retrieved results, which have been received from the switch controller, in the area 412 of memory 41. Similarly, the main controller 4 transmits instructions for retrieving (and for sending back the retrieved results) the states of the connections of the switch units of all discrete switches, namely the P discrete switches belonging to the primary switch group, the R discrete switches belonging to the secondary switch group and the Q discrete switches belonging to the tertiary switch group, and stores the received results of retrieval in the area 412 of memory 41. In the example set forth above, only a path connecting the input terminal X and the output terminal Y exists. Consequently, the states of the connections read out of the switch units of the discrete switches constitute the following information in FIGS. 1 through 3: input terminal 1K1 α and output terminal 1Kao are currently connected by switch 1K; input terminal 2Aki and output terminal 2A1Cbo are currently connected by switch 2A1C; input terminal 2A2Bci and output terminal 2A2Bfo are currently connected by switch 2A2B; input terminal 2A3Fbi and output terminal 2Aho are currently connected by switch 2A3F; and input terminal 3Hai and output terminal 3Hβo are currently connected by switch 3H. Using the above-mentioned connection information, the main controller 4 retrieves the fact that the output terminal 3Hβo of switch 3H of the tertiary switch group corresponds to the output terminal Y of the overall multistage switch [Y=(H-1) ×n+β] and, on the basis of the status of the connection in switch 3H, reads out the fact that the output terminal 3Hβo is currently connected to the input terminal 3Hai. Next, the main controller 4 retrieves the fact that the input terminal 3Hai of switch 3H is to be logically connected to the output terminal 2Aho of switch 2A of the secondary switch group 2, and retrieves the fact that output terminal 2Aho corresponds to the output terminal 2Aho of the switch 2A3F of the third stage of the secondary switch group. Next, on the basis of the status of the connection in switch 2A3F, the main controller 4 reads out the fact that the output terminal 2Aho is currently connected to the input terminal 2A3Fbi and retrieves the fact that the input terminal 2A3Fbi is to be logically connected to the output terminal 2A2Bfo of the switch 2A2B of the second stage. Next, on the basis of the status of the connection in switch 2A2B, the main controller 4 reads out the fact that the output terminal 2A2Bfo is currently connected to the input terminal 2A2Bci and retrieves the fact that the input terminal 2A2Bci is to be logically connected to the output terminal 2A1Cbo of the switch 2A1C of the first stage. Next, on the basis of the status of the connection in switch 2A, the main controller 4 retrieves the fact that the output terminal 2A1Cbo is currently connected to the input terminal 2Aki and retrieves the fact that the input terminal 2Aki of the switch 2A in the secondary switch group 2 is to be logically connected to the output terminal 1Kao of switch 1K in the primary switch group 1. Next, on the basis of the status of the connection in switch 1K, the main controller 4 retrieves the fact that the output terminal 1Kao is currently connected to the input terminal 1Kai and retrieves the fact that the input terminal 1Kai of switch 1K corresponds to the input terminal X [X=(K-1)×m+α] of the overall multistage switch. The main controller 4 stores the connection information relating to input terminal X and output terminal Y of the overall multistage switch, which information has been retrieved based upon the states of the connections read out of the switch units of the discrete switches, in the area 412 of memory 41, compares the connection information of the overall multistage switch that has been stored in the area 411 of memory 41 beforehand, and checks to determine whether the information in area 411 matches the information stored in area 412. A preferred embodiment of the present invention now be described in further detail with reference to the drawings. This embodiment of the present invention will be described in regard to a 3-stage switch having a switch size of N×M for selectively connecting M incoming lines and N outgoing lines, where M and N represent natural numbers. Each switch group of the 3-stage switch has a plurality of discrete switches and each discrete switch possesses a plurality of input terminals and a plurality of output terminals. FIG. 4 illustrates an example of the 3-stage switch, which includes P discrete switches (where P=M/m) of switch size m×r each selectively connecting m incoming lines and r outgoing lines (where m, r are natural numbers and m≦M holds) and belonging to the primary switch group 1; R switch groups each selectively connecting p incoming lines and q outgoing lines (where p, q are natural numbers) and belonging to the secondary switch group 2; Q discrete switches (where Q=N/n) each selectively connecting r incoming lines and n outgoing lines (where r, n are natural numbers and n≦N holds) and belonging to the tertiary switch group 3; and the main controller 4 for controlling connections through the primary, secondary and tertiary switches 1, 2 and 3, respectively. The main controller 4 has the memory 41 for storing the states of the connections of the discrete switches. The memory 41 is divided into the area 411 for storing connection information relating to the 3-stage switch, and the area 412 for storing the states of connections read out of the switch units of the discrete switches. The discrete switches belonging to each of the discrete switch groups have a switch unit for connecting one of a plurality of input terminals and one of a plurality of output terminals, and a switch controller for controlling the switch unit. By way of example, as shown in FIG. 5, the switch 1K belongs to the primary switch group 1 and incorporates the switch unit 1K1 and the switch controller 1K2. Similarly, the secondary switches 2A, 2R which belong to the secondary switch group 2 have switch units 2A1, 2R1, respectively, and switch controllers 2A2, 2R2, respectively. Likewise, the tertiary switches 3H, 3Q which belong to the tertiary switch group 3 have switch units 3H1, 3Q1, respectively, and switch controllers 3H2, 3Q2, respectively. The switch controller 1K2 of the primary switch 1K is connected to the main controller 4 by the control line 62. The switch controllers of the other discrete switches are connected to the main controller by control lines in a similar manner, as depicted in FIG. 5. The manner in which input and output terminals of each discrete switch are connected will be described with reference to FIG. 6. An ath (1≦a≦r) output terminal 1Kao of the Kth (1≦K≦P) switch 1K of primary switch group 1 is connected to a kth (1≦k≦p) input terminal 2Aki of the Ath (1≦A≦R) switch 2A of secondary switch group 2 by signal line 51. An hth (1≦h≦q) output terminal 2Aho of this switch 2A is connected to an ath (1≦a≦r) input terminal 3Hai of the hth (1≦H≦Q) switch 3H of tertiary switch group 3 by signal line 53. A kth (1≦k≦q) output terminal 2Ako of the switch 2A is connected to an ath input terminal 3Kai of the Kth switch 3K of tertiary switch group 3 by signal line 54. A bth (1≦b ≦r) output terminal 1Kbo of the switch 1K is connected to a kth input terminal 2Bki of the Bth (1≦B ≦R) switch 2B of secondary switch group 2 by signal line 52. An hth output terminal 2Bho of switch 2B is connected to a bth input terminal 3Hbi of switch 3H by signal line 55, and a kth output terminal 2Bko of switch 2B is connected to a bth input terminal 3Kbi of switch 3K by signal line 56. Accordingly, as illustrated in FIG. 4, the output terminals 1˜r of the first switch 11 in primary switch group 1 are connected to the first input terminals of the 1st˜rth switches 21˜2R, respectively, of secondary switch group 2. Similarly, the output terminals 1˜q of the first switch 21 in secondary switch group 2 are connected to the first input terminals of the switches 31˜3Q, respectively, of tertiary switch group 3. Thus, the output terminals of each discrete switch are cross-connected to the input terminals of the switches of the next stage. The operation of this embodiment of the present invention will now be described in detail with reference to the drawings. A case will be described in which there is a request to connect the input terminal X (where X≦M) and the output terminal Y (where Y≦N) of the overall 3-stage switch. The manner of path connection will be described first. The main controller 4 receives a connection request and responds by computing that the input terminal X corresponds to the input terminal α of the Kth switch 1K of primary switch group 1 and that the output terminal Y corresponds to the output terminal β of the Hth switch 3H of tertiary switch group 3. Next, the main controller 4 retrieves the status of use of output terminal β of switch 3H from the area 411 of memory 41 and executes the following processing based upon the results of retrieval: (1) In a case where the output terminal β of switch 3H is currently in use, an input terminal of the multistage switch that will make the connection to β (or Y) is retrieved. If the retrieved input terminal is X, the status is made "already connected" because the path for which connection was requested has already been connected. If the retrieved input terminal is different from X, then the status is made "connection impossible". (2) In a case where the output terminal β of switch 3H is not in use, the main controller 4 retrieves from the area 411 of memory 41 the states of use of output terminals 1˜r of switch 1K of primary switch group 1 successively starting from the first output terminal. For example, if 1st˜(a-1)th output terminals of switch 1K are in use and the ath output terminal 1Kao is not in use, the main controller 4 next retrieves the status of use of the hth output terminal 2Aho of switch 2A of secondary switch group 2 connected to switch 3H of tertiary switch group 3 to which output terminal β belongs. If the output terminal 2Aho is not in use, the main controller 4 connects the input terminal 1K αi and the output terminal 1Kao of switch 1K in primary switch group 1; connects the input terminal 2Aki and the output terminal 2Aho of switch 2A of the secondary switch group 2; and connects the input terminal 3Hai and the output terminal 3Hβo of switch 3H in tertiary switch group 3. As a result, a path connecting the input terminal X and the output terminal Y of the 3-stage switch can be acquired. Accordingly, instructions for connecting the above-mentioned input and output terminals are transmitted to the switch controllers of the discrete switches in each of the stages. If each discrete switch executes the connection of the requested path and connects the input and output terminals normally, then each discrete switch sends a signal indicative of "normal end" back to the main controller 4. Upon receiving the signals indicative of "normal end", the main controller 4 saves the established connection information in the area 411 of memory 41. If the output terminal 2Aho of switch 2A is in use, the main controller 4 retrieves the status of use of the bth (a<b) output terminal 1Kbo of switch 1K. If this output terminal is not in use, the main controller 4 next retrieves the status of use of the hth output terminal 2Bho of switch group 2B connected to switch 3H. The main controller 4 continues executing the above-described processing until a usable output terminal of a primary switch and a usable output terminal of a secondary switch are found. If a control line connecting the main controller 4 and the switch controller of a discrete switch is severed or if the switch controller of a discrete switch is reset, then, in order to make the connection information that has been stored in the area 411 of memory 41 of the main controller 4 agree with the connection states of the discrete switches, the main controller 4 overwrites the connection information the memory onto the discrete switches after communication between the main controller and the switch controller of the discrete switch is restored. The switch controller of a discrete switch that has received an overwrite connection instruction from the main controller 4 changes the connection status of the switch unit in accordance with the connection instruction. In this embodiment of the present invention, it is so arranged that when a request has been issued to connect input and output terminals of the overall 3-stage switch, agreement between the connection information that has been stored in the memory and the states of connections of the switch units of all discrete switches is verified before execution of processing for retrieving a path capable of being established by the switch units of the discrete switches constituting the 3-stage switch and before the information that has been stored in the memory is overwritten to the switch units of the discrete switches. By way of example, operation will be described in a case where a request to connect input terminal X and output terminal Y has been issued, or in a case where communication failure between the main controller 4 and a switch controller of a discrete switch constituting the multistage switch is restored and the connection information in area 411 of memory 41 is overwritten onto the switch units of the discrete switches, under conditions in which only a path connecting input terminal X and output terminal Y exists in the 3-stage switch having the switch size of M×N in FIGS. 4 through 6. Before retrieving a path connecting input terminal X and output terminal Y, or before transmitting overwrite connection instructions that are in accordance with the connection information in memory 411 of memory 41 to the switch controllers of the discrete switches, the main controller 4 sends the switch controller 112 of the 1st switch 11 of the primary switch group an instruction for retrieving the input terminal numbers of input terminals to which the 1st˜rth output terminals of switch 111 are connected, and for sending back the retrieved results. The main controller 4 then stores the retrieved results, which have been received from the switch controller 112, in the area 412 of memory 41. In the example set forth above, only a path connecting the input terminal X and the output terminal Y exists. Consequently, the states of the connections read out of the switch units of the discrete switches comprises the following information in FIGS. 4 through 6: input terminal 1Kαi and output terminal 1Kao are currently connected by switch 1K; input terminal 2Aki and output terminal 2Aho are currently connected by switch 2A; and input terminal 3Hai and output terminal 3Hβo are currently connected by switch 3H. Using the above-mentioned connection information, the main controller 4 retrieves the fact that the output terminal 311βo of switch 3H of the tertiary switch group corresponds to the output terminal Y of the overall multistage switch [Y=(H-1)×n+β] and, on the basis of the status of the connection in switch 3H, reads out the fact that the output terminal 3Hβo is currently connected to the input terminal 3Hai. Next, the main controller 4 retrieves the fact that the input terminal 3Hai of switch 3H is to be logically connected to the output terminal 2Aho of switch 2A of the secondary switch group, and retrieves the fact that output terminal 2Aho currently connected to the input terminal 2Aki of the switch 2A of the secondary switch group. Next, the main controller 4 retrieves the fact that the input terminal 2Aki of switch 2A is to be logically connected to the output terminal 1Kao of switch 1K of the primary switch group, retrieves, on the basis of the status of the connection in switch 1K, the fact that the output terminal 1Kao is currently connected to the input terminal 1Ka1, and retrieves the fact that the input terminal 1Kai of switch 1K corresponds to the input terminal X [X=(K-1)Xm+α] of the overall multistage switch. The main controller 4 stores the connection information relating to input terminal X and output terminal Y of the overall 3-stage switch, which information has been retrieved based upon the states of the connections read out of the switch units of the discrete switches, in the area 412 of memory 41, compares the connection information of the overall multistage switch that has been stored in the area 411 of memory 41 beforehand, and checks to determine whether the information in area 411 matches the information stored in area 412. The present invention offers the following advantages: (1) The first advantage of the present invention is that it is possible to prevent a connection path established for each discrete switch from being cut when there is a request to connect input and output terminals of a multistage switch under conditions in which there is no agreement between connection information of the overall multistage switch that has been stored in memory and the connection states that have been set for the switch units of the discrete switches. The reason for this is that when the connection of a new path has been requested, the present invention is such that it is possible to verify, prior to the execution of path connection processing, whether the multistage-switch connection information that has been stored in memory beforehand coincides with the states of the connections through the discrete switches. (2) The second advantage of the present invention is that it is possible to prevent the severance of a connected path. Specifically, if a control line connecting the main controller and the switch controller of a discrete switch has been cut, or if the switch controller of a discrete switch has been reset, the connection information in the memory of the main controller is generally overwritten as to the discrete switches, after communication between the main controller and switch controller is restored, in order to match the connection information that has been stored in the memory with the connection states of the switch units of the discrete switches. However, the system of the present invention for checking the connection information of the multistage switch is so adapted that it is possible to prevent a connection path from being cut by the overwriting of the connection information and establishing of a new path under conditions in which there is no agreement between connection information of the overall multistage switch that has been stored in memory and the connection states that have been set for the switch units of the discrete switches. The reason for this that it is possible to verify agreement between the connection information of the overall multistage switch that has been stored in memory and the connection states of the discrete switches before overwriting starts following restoration of communication between the main controller and the switch controller. As many apparently widely different embodiments of the present invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.

A multistage switch has an M×N switch size selectively connecting M incoming lines and N outgoing lines and consists of S stages of discrete switches each having a switch unit, wherein the discrete switches are permanently cross-connected in accordance with a prescribed rule. Stored connection information regarding the overall multistage switch and the states of connection of the switch units of the discrete switches are retrieved. Then, utilizing the fact that an output terminal of a switch in a cth (where c≦S-1) stage of the multistage switch is to be logically connected to an input terminal of a switch in a (c+1)th stage, connection information relating to the overall switch is generated from the results of retrieval. The generated connection information relating to the overall multistage switch is compared with connection information that has been stored in memory in advance, whereby a connection path that has been set for each discrete switch is prevented from being severed accidentally.

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This is a divisional application of application Ser. No. 10/825,634, filed Apr. 15, 2004, which application claims the benefit of U.S. Provisional Application No. 60/464,317, filed Apr. 21, 2003, both of which applications are hereby incorporated herein by reference in their entireties. FIELD OF THE INVENTION [0002] The present invention relates to electromagnetic pumps that move an electrically conductive fluid by interaction with magnetic fields. BACKGROUND OF THE INVENTION [0003] Electromagnetic pumps can be used to pump electrically conductive fluids, such as an electrically conductive molten metal composition. An advantage of an electromagnetic pump is that the fluid can be magnetically induced to move through a tube or conduit without the use of mechanical pump components inside of the conduit. [0004] Known electromagnetic pumps are either submersed in, or integrally attached to, the source of the electrically conductive fluid, such as a metal melting and/or melt holding furnace. These pump installations are difficult to service and maintain. Therefore there is the need for an efficient and easily maintainable electromagnetic pump that is not integrally attached to the source of the electrically conductive fluid. BRIEF SUMMARY OF THE INVENTION [0005] In one aspect, the invention is apparatus for and method of pumping an electrically conductive material in a pump having a supply section or volume, and a magnetic force pumping section or volume. In one example of the invention the directional flow of the material through the supply section is opposite to the directional flow of the material through the magnetic force pumping section. Multiple coils surround the supply and magnetic force pumping sections. Current flowing through the multiple coils creates magnetic fields that magnetically couple with a magnetic material disposed between the supply and magnetic force pumping sections so that the fields penetrate the electrically conductive material in the magnetic force pumping section substantially perpendicular to the desired flow direction. This field orientation maximizes the magnitudes of the magnetic forces applied to the electrically conductive material in the magnetic force pumping section. [0006] These and other aspects of the invention are set forth in the specification and the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS [0007] The figures, in conjunction with the specification and claims, illustrate one or more non-limiting modes of practicing the invention. The invention is not limited to the illustrated layout and content of the drawings. [0008] FIG. 1 is a side perspective view of one example of an electromagnetic pump of the present invention. [0009] FIG. 2 is a side elevational view of one example of an electromagnetic pump of the present invention. [0010] FIG. 3 ( a ) is a side sectional view through line A-A in FIG. 2 of one example of an electromagnetic pump of the present invention. [0011] FIG. 3 ( b ) is a top sectional view through line B-B in FIG. 2 of one example of an electromagnetic pump of the present invention. [0012] FIG. 3 ( c ) is a partial sectional view of the interface region for inner, mid and outer tubes, and magnetic material, used in one example of an electromagnetic pump of the present invention. [0013] FIG. 4 ( a ) is a simplified schematic diagram of a power supply and power distribution to induction coils used with an electromagnetic pump of the present invention. [0014] FIG. 4 ( b ) is a vector diagram illustrating one example of phase distribution of the output of a power supply to the induction coils used with an electromagnetic pump of the present invention. [0015] FIG. 5 is a side sectional view of another example of an electromagnetic pump of the present invention. DETAILED DESCRIPTION OF THE INVENTION [0016] Referring now to the drawings, wherein like numerals indicate like elements, there is shown in the figures one example of electromagnetic pump 10 of the present invention for pumping an electrically conductive material, such as an electrically conductive molten metal. In FIG. 1 , twelve induction coils ( 12 a through 12 l ) as further described below, are surrounded by a plurality of vertical magnetic shunts 14 held in place by shunt supports 16 , which are attached to base 18 at one end, and to yoke 20 at the opposing end. The base and yoke may optionally be formed from a magnetic material to provide bottom and top magnetic field containment. Other shunt and outer support arrangements as known in the art may be used in lieu of the shunt and support arrangements shown in FIG. 1 . Pump inlet 24 and pump outlet 22 in this non-limiting example of the invention, are cylindrically formed from a suitable heat-resistant material. [0017] Referring now to FIG. 3 ( a ), which is a side sectional of electromagnetic pump 10 shown in FIG. 2 , optional thermal insulator 26 separates the induction coils from the interior of the pump and provides a means for molten metal (melt) heat retention for melt in the pump. In this non-limiting example of the invention, the thermal insulator is substantially shaped as an open cylinder bounded by base 18 and yoke 20 . Outer tube 28 in this non-limiting example of the invention, is a substantially cylindrically-shaped tube that has a closed rounded bottom and an opened top with a protruding lip around the opening. The outer tube's lip sits on top of yoke 20 . First closing means 30 seats over yoke 20 and the protruding lip of the outer tube. Second closing means 32 seats over first closing means 30 . Outlet 22 is disposed between the first and second closing means. Mid tube 34 in this non-limiting example of the invention is a substantially cylindrically-shaped tube that is opened at both ends with the upper end having a protruding lip around the opening. The mid tube's lip is seated in a recess in second closing means 32 . The first and second closing means are arranged to form an outlet annular volume 42 that connects the interior passage of outlet 22 to riser annular volume 44 that is disposed between the outer wall of mid tube 34 and the inner wall of outer tube 28 . Third closing means 36 seats over second closing means 32 . Inner tube 40 in this non-limiting example of the invention is a substantially cylindrically-spaced tube that has an open bottom and a closed top. As best seen in FIG. 3 ( c ) the perimeter of the inner tube's open bottom forms a fluid tight seal with the perimeter of the mid tube's open bottom. Magnetic material 46 is disposed in a volume between the outer wall of inner tube 40 and the inner wall of mid tube 34 as further described below. Fourth closing means 38 seats over third closing means 36 and the closed top of inner tube 40 . Inlet 24 is disposed between the third and fourth closing means and its interior passage is connected to the interior passage of inner tube 40 . FIG. 3 ( b ) is a sectional view that illustrates the spatial relationship of components in a horizontal plane. [0018] The above non-limiting examples of the invention provide a convenient means for assembly or disassembly of pump 10 . Removal of fourth closing means 38 allows inlet 24 and inner tube 40 to be raised out of the pump. Further removal of third closing means 36 allows magnetic material 46 and mid tube 34 to be raised out of the pump. Further removal of second closing means 32 allows removal of outlet 22 . Further removal of first closing means 30 allows removal of outer tube 28 . [0019] The above examples of the invention provide a convenient means for changing the angular orientation between inlet 24 with outlet 22 . In a particular installation, supply and outlet conduit (not shown in the drawings) that are to be connected to inlet 24 and outlet 22 respectively, may not be oriented to accept the 180 degrees angular orientation (looking down on the top of the pump) between the inlet and outlet for pump 10 as shown in FIG. 1 . First closing means 30 and second closing means 32 may be rotated and secured into a position different from that shown in FIG. 1 to change the angular orientation of inlet 24 to outlet 22 , which outlet is contained by the first and second closing means. Third closing means 36 and fourth closing means 38 may be rotated and secured into a position different from that shown in FIG. 1 to change the angular orientation of outlet 22 to inlet 24 , which inlet is contained by the third and fourth closing means. [0020] Molten metal flows through pump 10 in the direction indicated by the arrows in FIG. 3 ( a ). The melt enters the pump through inlet 24 and flows down the interior cylindrical passage of inner tube 40 . This section of the pump is referred to as the supply section. The melt then moves by magnetic forces, as further described below, up riser annular volume 44 (the magnetic force pumping section), into outlet annular volume 42 , and finally out of the pump through outlet 22 . In other examples of the invention, outlet 22 may connect directly to riser annular volume 44 rather than being intermediately connected to it by outlet annular volume 42 formed between the inner wall of mid tube 34 and the inner annular walls of the first and second annular closing means. The outer tube, mid tube and inner tube are formed from a suitable heat resistant material such as a ceramic composition. One non-limiting type of ceramic composition that may used to cast the outer, mid and inner tubes, as well as inlet 24 and outlet 22 is a silicon-aluminum-oxynitride composition known as sialon. [0021] As disclosed above an applied magnetic force causes the electrically conductive melt to flow through pump 10 . There is shown in FIG. 4 ( a ) one diagrammatic example of supplying power to the induction coils to cause the molten metal to flow through pump 10 by magnetic force. Power supply 48 is a three-phase output power supply with variable output frequency and output voltage. One suitable type of supply is a solid state supply with a pulse width modulated output. FIG. 4 ( b ) is a vector diagram illustrating a six-cycle connection scheme from the power supply to the coils that is used to produced magnetic forces that act on the molten metal in riser annular volume 44 to force the melt up the riser annual volume and through outlet 22 , and thus pulling molten metal through pump 10 from a suitable source of molten metal that can be connected to inlet 24 . As illustrated in the diagram and vector diagram, the six-cycle scheme is created by sequentially connecting each of the three phases with alternating positive and negative phase orientation. That is phase +AB is followed by phase −BC, which is followed by phase +CA, which is followed by phase −AB, which is followed by phase +BC, which is followed by phase −CA. The six-cycle connection scheme for induction coils 12 a through 12 f repeats for induction coils 12 g through 12 l . The choice of a six-cycle connection scheme is not limiting, but a six-cycle scheme (with 30 electrical degrees phase angle between voltages in adjacent coils) provides a more uniform flow rate than, for example, a three-cycle scheme (with 60 electrical degrees phase angle between voltages in adjacent coils). Since the magnitude of the output voltage of power supply 48 is directly proportional to the magnitude of the magnetic force applied to the molten metal, varying the output voltage of the power supply will vary the magnetic lifting force and flow rate of a molten metal through the pump. [0022] The magnetic forces generated in riser annular volume 44 are substantially vertical in the upwards direction since the magnetic field generated around each of the coils substantially forms a magnetic circuit with magnetic material 46 and the field path through the molten metal in the riser annular volume is substantially horizontally-oriented. If a hot molten metal is pumped by electromagnetic pump 10 , magnetic material 46 must have a Curie temperature (point at which the magnetic material loses its magnetic properties) greater than the temperature of the molten metal flowing through the pump. For these applications a high Curie temperature magnetic material must be used. For example, molten aluminum typically may flow through the pump at a temperature ranging from 680° C. to 800° C. For this application the magnetic material must have a Curie temperature of at least 850° C. which is the maximum temperature of the aluminum melt plus design margin. One suitable type of high Curie temperature magnetic material 46 for this application is a class of iron-cobalt alloys known as permendur. [0023] It is preferable, but not required, that each induction coil be formed as a thin-wire, multiple-turn (typically 500 or more turns) coil commonly referred to as a bobbin magnetic coil since it is formed by winding thin wire around a bobbin that is removed after winding. Since the magnitude of magnetic force created by a magnetic field is directly proportional to both current flow through the coil and the number of turns in the coil, using a coil with a large number of turns keeps the required output current from power supply 48 at a low level for a given magnitude of magnetic force. [0024] If the source of molten metal to the pump is located below the horizontal level of inlet 24 , pump 10 will need to be initially primed by filing the interior passage of inner tube 40 with melt. One method of accomplishing this is by attaching a vacuum pump to outlet 22 and drawing a vacuum on the melt flow passages within pump 10 to suction melt from a supply of molten metal connected to inlet 24 . In other examples of the invention, the top of inner tube 40 may be open and penetrate through fourth closing means 38 in, for example, a funnel-shaped opening into which molten metal can be poured to prime the pump by filling the inner tube. [0025] When pump 10 is not in use, stationary molten metal in the pump may cool and “freeze” within the pump's internal flow passages. To prevent this from happening, a cyclical emptying and filling of riser annular volume 44 with molten metal may be electromagnetically accomplished. Reversing the direction of all phase vectors in FIG. 4 ( b ) will create a magnetic force on molten metal in riser annular volume 44 that will force it down and push molten metal back though inlet 24 to the source of molten metal connected to the inlet. Subsequently reversing all phase vectors back to the directions shown in FIG. 4 ( b ) will create a magnetic force that will cause molten metal to rise up in the riser annular volume. This jogging motion of molten metal will prevent freezing of molten metal in the pump when it is not in use. In other examples of the invention, if a three phase power supply is used, cyclically reversing two of the phases with, for example, solid state switches, can also be used to accomplish the electromagnetic jogging motion of melt in the pump. In other examples of the invention, a heating medium, such as a circulating hot gas or liquid, or an electric heating element, may be provided in the volume between thermal insulator 26 and the outer wall of outer tube 28 . [0026] FIG. 5 illustrates another example of an electromagnetic pump of the present example. In this example, inlet 24 a is at the bottom of the pump and molten metal is electromagnetically pumped directly up riser annular volume 44 as generally described in previous examples of the invention. In this particular example since molten metal does not flow through the inner tube, the inner tube may be a totally enclosed tube or other inner structural element that serves as a means for containing magnetic material 46 between the inner structural element and mid tube 34 . [0027] Other types of power supply and distribution arrangements are contemplated within the scope of the invention. For example, multiple single phase power supplies may be used; each coil may be powered by an individual power supply; or separate power supplies may power individual groups of coils. Further although in the above examples of the invention the inner, mid and outer tubes have their longitudinal axes vertically oriented, the longitudinal axes of the tubes may be otherwise oriented without deviating from the scope of the invention. [0028] The examples of the invention include reference to specific electrical components. One skilled in the art may practice the invention by substituting components that are not necessarily of the same type but will create the desired conditions or accomplish the desired results of the invention. For example, single components may be substituted for multiple components or vice versa. [0029] The foregoing examples do not limit the scope of the disclosed invention. The scope of the disclosed invention is further set forth in the appended claims.

An electromagnetic pump has a supply section and a magnetic force pumping section wherein flow of an electrically conductive material through the supply section is opposite to the flow of the material in the magnetic force pumping section in some examples. Multiple coils surround the supply and magnetic force pumping sections. Current flowing through the multiple coils creates magnetic fields that magnetically couple with a magnetic material disposed between the supply and magnetic force pumping sections so that the fields penetrate the electrically conductive material in the magnetic force pumping section substantially perpendicular to the desired flow direction which maximizes the magnitudes of magnetic forces applied to the electrically conductive material. Alternatively the electromagnetic pump has a supply section and a magnetic force pumping section wherein flow of an electrically conductive material through the supply section is in the same direction as the flow of the material in the magnetic force pumping section.

[0001] The present invention relates to a process for the preparation of certain chemical compounds. In particular, the present invention relates to a method for the preparation of compounds that have been shown to activate human peroxisome proliferator activated receptors (“hPPARs”). The present invention also relates to certain chemical compounds useful as intermediates in the preparation of hPPAR active compounds. BACKGROUND [0002] Several independent risk factors have been associated with cardiovascular disease. These include hypertension, increased fibrinogen levels, high levels of triglycerides, elevated LDL cholesterol, elevated total cholesterol, and low levels of HDL cholesterol. HMG CoA reductase inhibitors (“statins”) are useful for treating conditions characterized by high LDL-c levels. It has been shown that lowering LDL-c is not sufficient for reducing the risk of cardiovascular disease in some patients, particularly those with normal LDL-c levels. This population pool is identified by the independent risk factor of low HDL-c. The increased risk of cardiovascular disease associated with low HDL-c levels has not yet been successfully addressed by drug therapy (i.e. currently there are no drugs on the market that are useful for raising HDL-c). (Bisgaier, C. L.; Pape, M. E. Curr. Pharm. Des. 1998, 4, 53-70). [0003] Syndrome X (including metabolic syndrome) is loosely defined as a collection of abnormalities including hyperinsulemia, obesity, elevated levels of triglycerides, uric acid, fibrinogen, small dense LDL particles, and plasminogen activator inhibitor 1 (PAI-1), and decreased levels of HDL-c. [0004] NIDDM is described as insulin resistance, which in turn causes anomalous glucose output and a decrease in glucose uptake, by skeletal muscle. These factors eventually lead to impaired glucose tolerance (IGT) and hyperinsulinemia. [0005] Peroxisome Proliferator Activated Receptors (PPARs) are orphan receptors belonging to the steroid/retinoid receptor superfamily of ligand-activated transcription factors. See, for example Willson T. M. and Wahli, W., Curr. Opin. Chem. Biol., 1, pp235-241 (1997) and Willson T. M. et. al., J. Med. Chem., 43, p527-549 (2000). The binding of agonist ligands to the receptor results in changes in the expression level of MRNA's encoded by PPAR target genes. [0006] Three mammalian Peroxisome Proliferator-Activated Receptors have been isolated and termed PPAR-alpha, PPAR-gamma, and PPAR-delta (also known as NUC1 or PPAR-beta). These PPARs regulate expression of target genes by binding to DNA sequence elements, termed PPAR response elements (PPRE). To date, PPRE's have been identified in the enhancers of a number of genes encoding proteins that regulate lipid metabolism suggesting that PPARs play a pivotal role in the adipogenic signalling cascade and lipid homeostasis (H. Keller and W. Wahli, Trends Endocrinol. Metab 291-296, 4 (1993)). [0007] It has now been reported that thiazolidinediones are potent and selective activators of PPAR-gamma and bind directly to the PPAR-gamma receptor (J. M. Lehmann et. al., J. Biol. Chem. 12953-12956, 270 (1995)), providing evidence that PPAR-gamma is a possible target for the therapeutic actions of the thiazolidinediones. [0008] Activators of the nuclear receptor PPARγ, for example troglitazone, have been shown in the clinic to enhance insulin-action, reduce serum glucose and have small but significant effects on reducing serum triglyceride levels in patients with Type 2 diabetes. See, for example, D. E. Kelly et al., Curr. Opin. Endocrinol. Diabetes, 90-96, 5 (2), (1998); M. D. Johnson et al., Ann. Pharmacother., 337-348, 32 (3), (1997); and M. Leutenegger et al., Curr. Ther. Res., 403-416, 58 (7), (1997). [0009] The mechanism for this triglyceride lowering effect appears to be predominantly increased clearance of very low density lipoproteins (VLDL) through induction of lipoprotein lipase (LPL) gene expression. See, for example, B. Staels et al., Arterioscler. Thromb., Vasc. Biol., 1756-1764, 17 (9), (1997). [0010] Fibrates are a class of drugs which may lower serum triglycerides 20-50%, lower LDLc 10-15%, shift the LDL particle size from the more atherogenic small dense to normal dense LDL, and increase HDLc 10-15%. Experimental evidence indicates that the effects of fibrates on serum lipids are mediated through activation of PPARα. See, for example, B. Staels et al., Curr. Pharm. Des., 1-14, 3 (1), (1997). Activation of PPARα results in transcription of enzymes that increase fatty acid catabolism and decrease de-novo fatty acid synthesis in the liver resulting in decreased triglyceride synthesis and VLDL production/secretion. In addition, PPARα activation decreases production of apoC-III. Reduction in apoC-III, an inhibitor of LPL activity, increases clearance of VLDL. See, for example, J. Auwerx et al., Atherosclerosis, ( Shannon, Irel .), S29-S37,124 (Suppl), (1996). [0011] Certain compounds that activate or otherwise interact with one or more of the PPARs have been implicated in the regulation of triglyceride and cholesterol levels in animal models. See, for example, U.S. Pat. No. 5,847,008 (Doebber et al.) and U.S. Pat. No. 5,859,051 (Adams et al.) and PCT publications WO 97/28149 (Leibowitz et al.) and WO99/04815 (Shimokawa et al.). In a recent report (Berger et al., J. Biol. Chem. 1999), vol. 274, pp. 6718-6725) it was stated that PPARδ activation does not appear to modulate glucose or triglyceride levels. BRIEF DESCRIPTION [0012] The present invention relates to a process for the preparation of a compound of formula (IV): wherein, R 1 is selected from the group consisting of H, —Si(R 9 ) 3 , —C(R 10 R 10 )C(O) 2 H, benzyl, allyl, and C 1-6 alkyl; R 2 , R 3 , and R 4 are independently selected from the group consisting of H, C 1-3 alkyl, —OCH 3 , —CF 3 , allyl, and halogen; R 5 and R 6 are independently selected from the group consisting of H, phenyl, benzyl, C 1-6 -alkyl, and allyl; each R 7 is independently selected from —CF 3 , C 1-3 alkyl, —OCH 3 , or halogen; R 8 is selected from the group consisting of H, —CF 3 , and C 1-6 alkyl; one of Y and Z is N and the other is S or O; each R 9 is independently selected from C 1-6 alkyl, or arylC 1-6 alkyl, or two R 9 groups together with the silicon atom to which they are attached form a 5-7 membered ring; each R 10 is independently selected from H or C 1-3 alkyl, or both R 10 groups together with the carbon atom to which they are attached form a 3-6 membered ring; and n=0, 1, 2, 3, 4, or 5; comprising the steps of: a) treating of a compound of formula (I) with an alkyl lithium reagent, magnesium (0), or magnesium (0) followed by treating with a dihalo zinc (II) reagent, wherein, R 1 , R 2 , R 3 , and R 4 are as defined above; and X 1 is selected from the group consisting of Cl, Br, and I; b) followed by treating with sulfur; and c) followed by treating with a compound of formula (III), wherein, R 5 , R 6 , R 7 , R 8 , Y, Z, and n are as defined above; R 11 is Cl, Br, I, or —OS(O) 2 R 12 ; and R 12 is selected from the group consisting of C 1-6 alkyl, C 6-10 aryl, C 6-10 arylC 1-6 alkyl, and —CF 3 . [0031] Compounds of formula (IV) may be used as intermediates in the preparation of compounds that may activate human peroxisome proliferator activated receptors (hPPARs). Such compounds were disclosed in GB/0031107.6, filed Dec. 20, 2000. DETAILED DESCRIPTION OF THE INVENTION [0032] In the present process, the intermediate compounds may be isolated between steps (a) and (b) and/or (b) and (c). [0033] In a preferred aspect of the invention, intermediate compounds are not isolated between steps (a) and (b) or (b) and (c). [0034] In a preferred aspect of the invention is a process in which the compound of formula (I) is treated with an alkyl lithium reagent. [0035] More preferred is a process for the preparation of a compound of formula (IV), wherein R 1 is —Si(R 9 ) 3 , wherein each R 9 is independently selected from C 1-6 alkyl. [0036] Even more preferred is a process for the preparation of a compound of formula (IV), wherein R 1 is —Si(CH 3 ) 2 t-Bu. [0037] Most preferred is a process for the preparation of a compound of formula (IV), wherein R 1 is —C(R 10 R 10 )C(O) 2 H, and each R 10 is —CH 3 . [0038] More preferred is a process for the preparation of a compound of formula (IV), wherein R 2 is —CH 3 . [0039] More preferred is a process for the preparation of a compound of formula (IV), wherein R 3 and R 4 are hydrogen. [0040] More preferred is a process for the preparation of a compound of formula (IV), wherein R 5 and R 6 are hydrogen. [0041] More preferred is a process for the preparation of a compound of formula (IV), wherein n is 2, one R 7 is fluorine and the other is —CF 3 . [0042] Most preferred is a process for the preparation of a compound of formula (IV), wherein n is 2, one R 7 is fluorine in the ortho position and the other is —CF 3 in the para position. [0043] More preferred is a process for the preparation of a compound of formula (IV), wherein R 8 is —CH 3 . [0044] More preferred is a process for the preparation of a compound of formula (IV), wherein Y is S, and Z is N. [0045] More preferred is a process for the preparation of a compound of formula (IV), wherein R 10 is —CH 3 . [0046] More preferred is a process for the preparation of compounds of formula (IV), wherein R 11 is Cl or —OS(O) 2 R 12 , and R 12 is C 1-6 alkyl. [0047] More preferred is a process for the preparation of a compound of formula (IV), wherein X 1 is Br. [0048] In another aspect of the present invention are compounds of formula (IV) wherein: R 1 is selected from the group consisting of —Si(R 9 ) 3 ; R 2 , R 3 , and R 4 are independently selected from the group consisting of H. C 1-3 alkyl, —OCH 3 , —CF 3 , allyl, and halogen; R 5 and R 6 are independently selected from the group consisting of H, phenyl, benzyl, C 1-6 alkyl, and allyl; each R 7 is independently selected from —CF 3 , C 1-3 alkyl, —OCH 3 , or halogen; R 8 is selected from the group consisting of H, —CF 3 , and C 1-6 alkyl; one of Y and Z is N and the other is S or O; each R 9 is C 1 -alkyl, or arylC 1-6 alkyl, or two R 9 groups together with the silicon atom to which they are attached form a 5-7 membered ring; and n=0, 1, 2, 3, 4, or 5. [0057] More preferred are compounds of formula (IV), wherein R 1 is —Si(CH 3 ) 2 t-Bu. [0058] More preferred are compounds of formula (IV), wherein R 2 is —CH 3 [0059] More preferred are compounds of formula (IV), wherein R 3 , R 4 , R 5 , and R 6 are hydrogen. [0060] More preferred are compounds of formula (IV), wherein n is 2, and one R 7 is fluorine and the other is —CF 3 . [0061] Most preferred are compounds of formula (IV), wherein n is 2, one R 7 is fluorine in the ortho position and the other is —CF 3 in the para position. [0062] More preferred are compounds of formula (IV), wherein R 8 is —CH 3 . [0063] More preferred are compounds of formula (IV), wherein Y is S, and Z is N. [0064] In another aspect of the invention is featured a process for the preparation of compounds of formula (III), said process comprising the step of treating a compound of formula (XVII) with thioacetic acid, wherein: each R 7 is independently selected from —CF 3 , C 1-3 alkyl, —OCH 3 , or halogen; and n=0, 1, 2, 3, 4, or 5. [0067] In another aspect of the present invention is featured a process for the preparation of a compound of formula (III), said process comprising the steps of: a) treating a compound of formula (XVII) with thioacetic acid; followed by b) treating with an α-halo-β-ketoester. [0070] In another aspect of the present invention is featured a process for the preparation of a compound of formula (III), said process comprising the steps of: a) treating a compound of formula (XVII) with thioacetic acid; followed by b) treating with an α-halo-β-ketoester; and c) treating with reducing agent. [0074] In another aspect of the present invention are featured compounds of formula (V), wherein: R 13 is C 1-6 alkyl, or arylC 1-6 alkyl, or two R 9 groups together with the silicon atom to which they are attached form a 5-7 membered ring. [0076] Another aspect of the present invention features a process for the preparation of compounds of formula (IV), wherein R 1 is —H, and R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , Y, Z, and n are as defined above, said process further comprising the step of treating a compound of formula (IV), wherein R 1 is —Si(CH 3 ) 2 t-Bu, with a base. [0077] Another aspect of the present invention features a process for the preparation of compounds of formula (IV), wherein R 1 is —C(R 10 R 10 )C(O) 2 H, R 10 is —CH 3 , and R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , Y, Z, and n are as defined above, said method further comprising the steps of: d) treating a compound of formula (IV), wherein R 1 is —Si(CH 3 ) 2 t-Bu, with a base; and e) treating with an alkylating agent. [0080] Another aspect of the invention features a process for the preparation of compounds of formula (IV), wherein R 1 is —C(R 10 R 10 )C(O) 2 H, R 10 is —CH 3 , and R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , Y, Z, and n are as defined above, said method further comprising the steps of: d) treating a compound of formula (IV), wherein R 1 is —Si(CH 3 ) 2 t-Bu, with a base; and e) treating with 1,1,1-trichloro-2-methylpropan-2-ol. [0083] The compounds according to the invention may contain one or more asymmetric atoms and thus occur as racemates, racemic mixtures, single enantiomers, diastereomeric mixtures and individual diastereoisomers. All such isomeric forms of these compounds are expressly included in the present invention. Each stereogenic atom may be of the R or S configuration. Although the specific compounds exemplified in this application may be depicted in a particular stereochemical configuration, compounds having either the opposite stereochemistry at any given chiral center or mixtures thereof are also envisioned. When a compound of formula (IV) is desired as a single enantiomer, it may be obtained either by resolution of the final product or by stereospecific synthesis using methods known to those skilled in the art. See, for example, Stereochemistry of Organic Compounds by E. L. Eliel and S. H. Wilen (Wiley Interscience, 1994). [0084] The terms “C 1-3 alkyl” and “C 1-6 -alkyl,” alone or in combination with any other term, refers to a straight-chain or branched-chain saturated aliphatic hydrocarbon radical containing the specified number of carbon atoms. Examples of alkyl radicals include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isoamyl, n-hexyl and the like. [0085] The term “C 6-14 aryl” alone or in combination with any other term, refers to a carbocyclic aromatic moiety (such as phenyl or naphthyl) containing the specified number of carbon atoms, preferably from 6-14 carbon atoms, and more preferably from 6-10 carbon atoms. Examples of aryl radicals include, but are not limited to phenyl, naphthyl, indenyl, indanyl, azulenyl, fluorenyl, anthracenyl and the like. [0086] The term “halogen” refers to fluorine, chlorine, bromine or iodine. [0087] As used in herein, the term “alkyl lithium reagent” refers to a chemical compound that consists of an anionic C 1-6 -alkyl portion and a corresponding lithium cation. Examples of such alkyl lithium reagents are n-butyl lithium, sec-butyl lithium, and tert-butyl lithium. Such alkyl lithium reagents are commercially available, conveniently as solutions in an appropriate solvent such as hexanes or cyclohexane, or may be prepared by methods known to those skilled in the art. [0088] As used herein, the term “sulfur” refers to elemental sulfur. [0089] As used herein, the term “intermediate compounds” refers to chemical compounds that are products of steps that comprise a chemical process. Such intermediates may or may not be amenable to chemical isolation, depending on their structure, chemical stability, or chemical reactivity. [0090] As used herein, the term “ortho position” refers to the position on an aryl ring that is disposed in a 1,2-orientation relative to another substituent on said ring. For example, in the compound 1-chloro-2-methyl benzene the methyl group is oriented ortho to the chloro substituent. [0091] As used herein, the term “para position” refers to the position on an aryl ring that is disposed in a 1,4-orientation relative to another substituent on said ring. For example, in the compound 1-chloro-4-methyl benzene the methyl group is oriented para to the chloro substituent. [0092] As used herein, the term “base” refers to chemical compounds known to those skilled in the art as either Bronsted or Lewis bases. Examples of such bases known to those skilled in the art include lithium hydroxide, sodium hydroxide, potassium hydroxide, trialkylamines such as triethylamine, and tetraalkyl ammonium halides such as tetra-n-butylammonium fluoride. In addition, included are compounds known to those skilled in the art to afford aqueous solutions that are basic in nature. Examples of such compounds are sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate. [0093] As used herein, the term “α-halo-β-ketoester” refers to a compound of formula (XXII), wherein: R 15 is halogen; R 16 is C 1-6 alkyl, C 3-8 cycloalkyl, C 6-14 aryl, or C 6-14 arylC 1-6 alkyl; and R 17 is hydrogen, —CF 3 , or C 1-6 alkyl. [0097] As used herein, the term “reducing agent” refers to a reagent or combination of reagents known to those skilled in the art capable of reducing an α-halo-β-ketoester. Among these reagents or combination of reagents are lithium aluminum hydride, borane, and di-isobutylaluminum hydride (DIBAL). [0098] As used herein, the term “magnesium (0)” refers to elemental magnesium in a form known to those skilled in the art to be useful in preparing so-called “Grignard reagents.” Among such magnesium (0) forms are magnesium turnings and activated magnesium (0), so called “Rieke magnesium.” [0099] As used herein, the term “dihalo zinc (II) reagent” refers to a compound containing two halogen atoms and zinc in the (II) oxidation state. Among such reagents known to those skilled in the art to be useful in such processes are zinc (II) bromide, zinc (II) iodide, and zinc (II) chloride. [0100] Compounds of formulae (I) and (Ill) may be prepared by methods known to those of skill in the art. The following synthetic schemes are meant to represent examples only and are not meant to limit the invention in any way. In all of the schemes described below, it is understood that protecting groups may be employed where necessary in accordance with general principles known to those skilled in the art, for example, see T. W. Green and P. G. M. Wuts (1991) Protecting Groups in Organic Synthesis, John Wiley & Sons. These groups may be removed at a convenient stage of the compound synthesis using methods known those of skill in the art. The selection of processes as well as the reaction conditions and order of their execution shall be consistent with the preparation of compounds of formulae (I) and (III). Those of skill in the art will recognize that if a stereocenter exists in compounds of Formulas (I) and (III), and (IV) the present invention is meant to include both enantiomers, mixtures of such enantiomers and the individual enantiomers substantially free of the opposite enantiomer. In addition, when a compound contains more than one stereocenter, one of skill in the art will recognize that the present invention is meant to include mixtures of diastereomeric compounds, mixtures of enantiomers and the individual enantiomers substantially free of the opposite enantiomer. [0101] Compounds of formula (IV), wherein, R 1 is selected from the group consisting of H, —Si(R 9 ) 3 , —C(R 10 R 10 )C(O) 2 H, benzyl, allyl, and —CH 3 ; R 2 , R 3 , and R 4 are independently selected from the group consisting of H, C 1-3 alkyl, —OCH 3 , —CF 3 , allyl, and halogen; R 5 and R 6 are independently selected from the group consisting of H, phenyl, benzyl, C 1-6 alkyl, and allyl; each R 7 is independently selected from —CF 3 , C 1-3 alkyl, —OCH 3 , or halogen; R 8 is selected from the group consisting of H, —CF 3 , and C 1-6 -alkyl; one of Y and Z is N and the other is S or O; each R 9 is independently selected from C 1-6 alkyl, arylC 1-6 alkyl, or two R 9 groups together with the silicon atom to which they are attached form a 5-7 membered ring; each R 10 is independently selected from H or C 1-3 alkyl, or both R 10 groups together with the carbon atom to which they are attached form a 3-6 membered ring, and at least one R 9 group must be other than H; and n=0, 1, 2, 3, 4, or 5; are prepared by a process in which a compound of formula (I) is treated with an alkyl lithium reagent, magnesium (0), or magnesium (0) followed by treating with a dihalo zinc (II) reagent, wherein, R 1 , R 2 , R 3 , and R 4 are as defined above; and X 1 is selected from the group consisting of Cl, Br, and I; followed by treatment with sulfur, and then followed by treatment with a compound of formula (III), wherein, R 5 , R 6 , R 7 , R 8 , Y, Z, and n are as defined above; R 11 is Cl, Br, I, or —OS(O) 2 R 12 ; and R 12 is selected from the group consisting of C 1-6 alkyl, C 6-10 aryl, and C 6-10 arylC 1-6 alkyl, and —CF 3 . [0118] These reactions may be performed in a manner in which intermediate compounds are isolated before using them in the next appropriate chemical step. For example, a compound of formula (I), wherein R 1 is —Si(R 9 ) 3 , and R 2 , R 3 , R 4 , X 1 , and R 9 are as hereinbefore defined, may be treated with an alkyl lithium reagent to affect what is known to those skilled in the art as a halogen-metal exchange reaction, followed by treatment with sulfur and isolation of the intermediate product of formula (V), wherein: R 13 is C 1-6 -alkyl, or arylC 1-6 alkyl, or two R 9 groups together with the silicon atom to which they are attached form a 5-7 membered ring. [0120] These reactions are typically performed in an aprotic solvent, such as tetrahydrofuran (THF) or preferably methyl tert-butyl ether (MTBE), and at a temperature from −78° C. to 0° C., preferably −30° C. Further, the alkyl lithium reagent may be one known to those skilled in the art capable of effecting a halogen-metal exchange reaction, such as sec-butyl lithium, tert-butyl lithium, or preferably n-butyl lithium. Such alkyl lithium reagents are commercially available, conveniently in an appropriate solvent such as hexanes or cyclohexanes, or may be prepared by methods known to those skilled in the art. [0121] The compound of formula (V) may then be treated with a base to deprotonate the thiol to form a thiolate anion, followed by treatment with a compound of formula (III), to afford a compound of formula (IV). [0122] Alternatively, compounds of formula (IV) may be prepared by a process in which a compound of formula (I) is treated with an appropriate alkyl lithium reagent, n-butyl lithium for example, in an appropriate solvent, MTBE for example, at a temperature from −78° C. to 0° C., preferably −30° C., followed by treatment with sulfur, and then followed by treatment with a compound of formula (III). In this embodiment, the compound of formula (V) is not isolated, but instead the desired thiolate is generated in situ and is allowed to react with a compound of formula (III) to afford a compound of formula (IV). These reactions are typically performed by adding an appropriate alkyl lithium reagent to the compound of formula (I) to affect a halogen-metal exchange reaction, followed by the addition of sulfur to the reaction mixture, and finally adding the resulting thiolate to a solution of a compound of formula (III). The reaction may also be performed in the reverse manner in which the compound of formula (III) is added to a solution of the in situ generated thiolate. For example, as shown in Scheme I, (4-bromo-2-methylphenoxy)(tert-butyl)dimethylsilane was allowed to react with n-butyl lithium (n-BuLi), followed by treatment with sulfur to afford a compound of formula (VI). In a separate reaction vessel, [2-(2-fluoro-4-methylphenyl)4-methyl-1,3-thiazol-5-yl]methanol (VII) was allowed to react with methanesulfonyl chloride in the presence of triethylamine to afford a compound of formula (VIII), wherein LG is —Cl or —OS(O) 2 CH 3 or a mixture thereof. The solution of compound (VI) was then added to a solution of compound (VIII) to afford 5-{[(4-{[tert-butyl(dimethyl)silyl]oxy}-3-methylphenyl)thio]methyl)2-[2-fluoro4-(trifluoromethyl)phenyl]4-methyl-1,3-thiazole (IX). The thiolate structure shown for intermediate compound (VI) is presented only as an example and is not meant to limit the scope of the present invention in any way. [0123] Alternatively, compounds of formula (IV) may be prepared by a process in which a compound of formula (I) is treated with an appropriate magnesium (0) reagent, in an appropriate solvent, THF or MTBE for example, at a temperature from ambient to 50° C., followed by treatment with sulfur, and then followed by treatment with a compound of formula (III). In this embodiment, the compound of formula (V) is not isolated, but instead the desired thiolate is generated in situ and is allowed to react with a compound of formula (III) to afford a compound of formula (IV). [0124] Alternatively, compounds of formula (IV) may be prepared by a process in which a compound of formula (I) is treated with an appropriate magnesium (0) reagent, in an appropriate solvent, MTBE for example, at a temperature from ambient to 50° C., followed by treating with a dihalo zinc (II) reagent, followed by treating with sulfur, and then followed by treating with a compound of formula (III). In this embodiment, the compound of formula (V) is not isolated, but instead the desired thiolate is generated in situ and is allowed to react with a compound of formula (III) to afford a compound of formula (IV). [0125] The compounds of formula (I), wherein R 1 is —Si(R 9 ) 3 , and R 2 , R 3 , R 4 , R 9 and X 1 are as hereinbefore defined, are either commercially available or may be prepared from compounds of formula (I) wherein R 1 is H by methods known to those skilled in the art. These reactions are typically performed in an aprotic solvent, such as dichloromethane, chloroform, or preferably toluene, and in the presence of an appropriate trialkylsilyl trifluoromethanesulfonate or trialkylsilyl chloride, tert-butyldimethylsilyl chloride for example, and at a temperature from −30° C. to 30° C., preferably 10-15° C. In addition, the reaction may be performed in the presence of a catalyst, for example 4-dimethylaminopyridine (DMAP). [0126] Compounds of formula (I), wherein R 1 is —Si(R 9 ) 3 , R 2 , R 3 , R 4 , R 9 and X 1 are as hereinbefore defined, are either commercially available or may be prepared from compounds of formula (I) wherein R 1 and X 1 are H by methods known to those skilled in the art. The silylation reactions are typically performed in an aprotic solvent, such as dichloromethane, chloroform, or preferably toluene, and in the presence of an appropriate trialkylsilyl chloride, tert-butyldimethylsilyl chloride for example, and at a temperature from −30° C. to 30° C., preferably 10-15° C. In addition, the reaction may be performed in the presence of a catalyst, for example 4-dimethylaminopyridine (DMAP). The halogenation reactions are typically performed in an aprotic solvent, acetonitrile for example, at a temperature from 0° C. to 50° C., preferably ambient temperature, and in the presence of a compound capable of halogenating the benzene ring, N-bromosuccinimide, for example. For example, as shown in Scheme II, a solution of o-cresol in toluene, and in the presence of DMAP, was allowed to react with t-butyldimethylsilyl chloride to afford compound (X). Subsequently, compound (X) was allowed to react with NBS in acetonitrile to afford (4-bromo-2-methylphenoxy)(tert-butyl)dimethylsilane (XI). wherein, R 5 , R 6 , R 7 , R 8 , Y, Z, and n are as defined above; R 11 is Cl, Br, I, or —OS(O) 2 R 12 ; and R 12 is selected from the group consisting of C 1-6 alkyl, C 6-10 aryl, C 6-10 arylC 1-6 alkyl, and —CF 3 ; may be prepared from compounds of formula (III), wherein R 11 is —OH, and R 5 , R 6 , R 7 , R 8 , Y, Z, and n are as defined above, by reaction with a reagent, or combination of reagents, capable of converting the hydroxy group into a leaving group, such as a halide or alkyl or aryl sulfonyl group. These reactions are typically performed in an aprotic solvent such as dichloromethane, chloroform, acetonitrile, MTBE, or preferably a mixture of acetonitrile and MBTE, in the presence of a base, triethylamine for example, and at a temperature from −78° C. to 25° C., preferably −20 to −15° C. Among the reagents or combination of reagents that are capable of converting the hydroxy group to a leaving group are p-toleuensulfonyl chloride, or preferably methanesulfonyl chloride, in the presence of a base such as pyridine, DMAP, or preferably triethylamine. For example, {2-[2-fluoro-4-(trifluoromethyl)phenyl]4-methyl-1,3-thiazol-5-yl}methanol (XIII) was allowed to react with methanesulfonyl chloride in a mixture of acetonitrile and MTBE and in the presence of triethylamine at a temperature of −15 to −20° C. to afford either 5-(chloromethyl)-2-[2-fluoro-4-(trifluoromethyl)phenyl]-4-methyl-1,3-thiazole (XIV) or {2-[2-fluoro-4-(trifluoromethyl)phenyl]-4-methyl-1,3-thiazol-5-yl}methyl methanesulfonate (XV), or a mixture of both. [0131] Compounds of formula (III), wherein R 11 is —OH, and R 5 , R 6 , R 7 , R 8 , Y, Z, and n are as defined above, may be prepared from compounds of formula (XVI), wherein R 7 , R 8 , Y, Z, and n are as hereinbefore defined and R 14 is C 1-6 -alkyl, by reaction with a reagent or combination of reagents known to those skilled in the art capable of reducing an ester to an alcohol or capable of addition to an ester. Among such reagents known to those skilled in the art are lithium aluminum hydride (LAH), alkyl lithium reagents, or alkyl magnesium halides (so-called “Grignard” reagents). These reactions are typically performed in an aprotic solvent such as THF and at a temperature from −78 to 0° C., preferably −10 to −15° C. For example, a THF solution of ethyl 2-[2-fluoro-4-(trifluoromethyl)phenyl]-4-methyl-1,3-thiazole-5-carboxylate (XVII) was allowed to react with LAH at −10 to −15° C. to afford (2-[2-fluoro-4-(trifluoromethyl)phenyl]-4-methyl-1,3-thiazol-5-yl}methanol (XIII). [0132] Compounds of formula (XVI), wherein R 7 , R 8 , Y, Z, and n are as hereinbefore defined and R 14 is C 1-6 alkyl, may be prepared from compounds of formula (XVII), wherein R 7 and n are as hereinbefore defined. Compounds of formula (XVII) may be allowed to react with a suitable sulfur donor, thioacetic acid for example, in the presence an appropriate Lewis acid, boron trifluoride etherate for example, in an aprotic solvent, toluene for example, and at a temperature from 0° C. to 50° C., preferably 20° C. See, J. Y. Gauthier, et al. Phosphorous, Sulfur, and Silicon, 1994, Vol. 95-96, pp. 325-326. For example, as shown in Scheme III, 2-fluoro-4-(trifluoromethyl)benzonitrile was allowed to react with thioacetic acid in toluene and in the presence of boron trifluoride etherate to afford 2-fluoro4-(trifluoromethyl)benzenecarbothioamide (XVIII). Compound (XVIII) may then be allowed to react with and α-halo-β-keto ester, such as ethyl 2-chloroacetoacetate, in an aprotic solvent, toluene for example, and at a temperature of 75° C. to 125° C., preferably 100° C., to afford ethyl 2-[2-fluoro-4-(trifluoromethyl)phenyl]4-methyl-1,3-thiazole-5-carboxylate (XIX). [0133] Compounds of formula (XVII) are either commercially available or may be prepared by methods known to those skilled in the art. [0134] Compounds of formula (IV), wherein R 1 is H and R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , Y, Z, and n are as hereinbefore defined may be prepared from compounds of formula (IV), wherein R 1 is —Si(R 9 ) 3 , and R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 , Y, Z, and n are as hereinbefore defined by reaction with a reagent or combination of reagents known to those skilled in the art capable of acting as either a Bronsted or Lewis base. Among the reagents known to those skilled in the art capable of acting as either Bronsted or Lewis base include lithium hydroxide, sodium hydroxide, potassium hydroxide, trialkylamines such as triethylamine, and tetraalkyl ammonium halides such as tetra-n-butylammonium fluoride. In addition, included are compounds known to those skilled in the art to afford aqueous solutions that are basic in nature. Examples of such compounds are sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate. For example, as shown in Scheme IV, 5-{[(4-{[tert-butyl(dimethyl)silyl]oxy}-3-methylphenyl)thio]methyl}-2-[2-fluoro-4-(trifluoromethyl)phenyl]-4-methyl-1,3-thiazole (IX) was allowed to react with sodium hydroxide solution to afford 4-[({2-[2-fluoro-4-(trifluoromethyl)phenyl]-4-methyl-1,3-thiazol-5-yl}methyl)thio]-2-methylphenol (XX). [0135] Compounds of formula (IV), wherein R 1 is —C(R 10 R 10 )C(O) 2 H, and R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 10 , Y, Z, and n are as hereinbefore defined may be prepared from compounds of formula (IV), wherein R 1 is —OH, and R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , Y, Z, and n are as hereinbefore defined, by reaction with a reagent capable of alkylating the phenol to provide the desired product. Among the reagents capable of alkylating the phenol to provide the desired product is 1,1,1-trichloro-2-methyl-propanol. The alkylation reaction may be performed in a polar solvent, acetone for example, in the presence of a base, sodium hydroxide for example, and at a temperature of 0-50° C., preferably 36-38° C. For example, as shown in Scheme IV, 4-[({2-[2-fluoro-4-(trifluoromethyl)phenyl]-4-methyl-1,3-thiazol-5-yl}methyl)thio]-2-methylphenol (XX) was allowed to react with 1,1,1-trichloro-2-methyl-propanol in acetone and in the presence of sodium hydroxide to afford 2-{4-[({2-[2-fluoro-4-(trifluoromethyl)phenyl]-4-methyl-1,3-thiazol-5-yl}methyl)thio]-2-methylphenoxy}-2-methylpropanoic acid (XXI). EXAMPLES [0136] As used herein the symbols and conventions used in these processes, schemes and examples are consistent with those used in the contemporary scientific literature, for example, the Journal of the American Chemical Society or the Journal of Biological Chemistry. Standard single-letter or three-letter abbreviations are generally used to designate amino acid residues, which are assumed to be in the L-configuration unless otherwise noted. Unless otherwise noted, all starting materials were obtained from commercial suppliers and used without further purification. Specifically, the following abbreviations may be used in the examples and throughout the specification: g (grams); mg (milligrams); L (liters); mL (milliliters); μL (microliters); psi (pounds per square inch); M (molar); mM (millimolar); i. v. (intravenous); Hz (Hertz); MHz (megahertz); mol (moles); mmol (millimoles); rt (room temperature); min (minutes); h (hours); mp (melting point); TLC (thin layer chromatography); T r (retention time); RP (reverse phase); MeOH (methanol); i-PrOH (isopropanol); TEA (triethylamine); TFA (trifluoroacetic acid); TFAA (trifluoroacetic anhydride); THF (tetrahydrofuran); DMSO (dimethylsulfoxide); AcOEt (ethyl acetate); DME (1,2-dimethoxyethane); DCM (dichloromethane); DCE (dichloroethane); DMF (N,N- dimethylformamide); DMPU (N,N′-dimethylpropyleneurea); (CDI (1,1-carbonyldiimidazole); IBCF (isobutyl chloroformate); HOAc (acetic acid); HOSu (N-hydroxysuccinimide); HOBT (1-hydroxybenzotriazole); mCPBA (meta-chloroperbenzoic acid; EDC (ethylcarbodiimide hydrochloride); BOC (tert-butyloxycarbonyl); FMOC (9- fluorenylmethoxycarbonyl); DCC (dicyclohexylcarbodiimide); CBZ (benzyloxycarbonyl); Ac (acetyl); atm (atmosphere); TMSE (2-(trimethylsilyl)ethyl); TMS (trimethylsilyl); TIPS (triisopropylsilyl); TBS (t-butyldimethylsilyl); DMAP (4-dimethylaminopyridine); BSA (bovine serum albumin) ATP (adenosine triphosphate); HRP (horseradish peroxidase); DMEM (Dulbecco's modified Eagle medium); HPLC (high pressure liquid chromatography); BOP (bis(2-oxo-3-oxazolidinyl)phosphinic chloride); TBAF (tetra-n-butylammonium fluoride); HBTU (O-Benzotriazole-1-yl-N,N,N′,N′-tetramethyluronium hexafluorophosphate). HEPES (4-(2-hydroxyethyl)-1-piperazine ethane sulfonic acid); DPPA (diphenylphosphoryl azide); fHNO 3 (fumed HNO 3 ); and EDTA (ethylenediaminetetraacetic acid). [0137] All references to ether are to diethyl ether; brine refers to a saturated aqueous solution of NaCl. Unless otherwise indicated, all temperatures are expressed in ° C. (degrees Centigrade). All reactions are conducted under an inert atmosphere at room temperature unless otherwise noted. [0138] 1 H NMR spectra were recorded on a Varian VXR-300, a Varian Unity-300, a Varian Unity-400 instrument, or a General Electric QE-300. Chemical shifts are expressed in parts per million (ppm, δ units). Coupling constants are in units of hertz (Hz). Splitting patterns describe apparent multiplicities and are designated as s (singlet), d (doublet), t (triplet), q (quartet), m (multiplet), br (broad). [0139] Low-resolution mass spectra (MS) were recorded on a JOEL JMS-AX505HA, JOEL SX-102, or a SCIEX-APIiii spectrometer; high resolution MS were obtained using a JOEL SX-102A spectrometer. All mass spectra were taken under electrospray ionization (ESI), chemical ionization (CI), electron impact (EI) or by fast atom bombardment (FAB) methods. Infrared (IR) spectra were obtained on a Nicolet 510 FT-IR spectrometer using a 1-mm NaCl cell. All reactions were monitored by thin-layer chromatography on 0.25 mm E. Merck silica gel plates (60F-254), visualized with UV light, 5% ethanolic phosphomolybdic acid or p-anisaldehyde solution. Flash column chromatography was performed on silica gel (230-400 mesh, Merck). Example 1 Preparation of ethyl 2-[2-fluoro4-(trifluoromethyl)phenyl]-4-methyl-1,3-thiazole-5-carboxylate (XIX) [0140] [0141] A reactor was charged with toluene (4 vol), thioacetic acid (1.0 vol), and boron trifluoride etherate (1.64 vol). A solution of 2-fluoro4-trifluoromethylbenzonitrile (1 eq, 1 wt) in toluene (1 vol) is added to the mixture via a pump over 60 minutes with reaction control at 20° C. After the addition is complete, the mixture is allowed to stir for 3 hours. The temperature is then brought to 5° C. Process water (1 vol) is added over 30 minutes to quench boron trifluoride with reaction control at 5° C. Once the quenching is complete, process water (3 vol) is added to dilute the reaction mixture. The aqueous layer is separated, and 10% ammonia solution (4 vol) is added over 30 minutes. The reaction is highly exothermic and active cooling is engaged (reaction control at 5° C.). CAUTION: The ammonia washing is separated from the toluene phase. The mixture is brought to 20° C. with reaction control at 20° C. The organic layer is washed with process water (2×4 vol) and concentrated under reduced pressure (90-60 mm Hg, 50° C.) to 3 vol. The mixture is used directly in the condensation with ethyl 2-chloroacetoacetate. Ethyl 2-chloroacetoacetate (1.1 eq, 0.8 vol) is added to the toluene solution and the mixture is heated at 100° C. (reaction control) until the reaction is complete (ca. 14 hours). The reaction mixture is cooled to 50° C. Toluene (2 vol) is removed under reduce pressure (90-60 mm Hg, 50° C.). The volume reduces to 3 vol. Ethanol (4 vol) is added and solvent (4 vol) is removed. During the concentration, batch temperature is maintained at 35-40° C. (jacket ca. 70 ° C.), vacuum at 140 mmHg. When the temperature gets lower than 28° C., product will precipitate out of the mixture. Ethanol (4 vol) is added and the volume reduces to 6 vol, followed by adding process water (0.3 vol). The mixture is allowed to cool to 20° C. over 1 hour and remain there for 1 h. The solid is collected by filtration, washed with cold aqueous ethanol prepared above, sucked to dryness, and dried under vacuum at 40° C. to a constant weight. Example 2 Preparation of {2-[2-fluoro-4-(trifluoromethyl)phenyl]-4-methyl-1,3-thiazol-5-yl}methanol (XIII) [0142] [0143] A reactor was charged with THF (4 vol) and 1 M LAH/THF (0.62 eq, 1.85 vol). The temperature is set in reaction control and brought to −15° C. Compound (XIX) (1 eq, 1 wt). is dissolved in THF (2 vol) and the solution is added using a metering pump over 1.5 hour while keeping the temperature between −10 and −15° C. After the addition is complete, the mixture is allowed to stir at that temperature for 0.5 h. In process check (IPC) confirms that the starting material was completely consumed. The reaction was then quenched by adding a mixture of process water and THF (1/1, 0.15 vol) over 30 minutes, 20% NaOH solution (0.056 vol) over 15 minutes, and process water (0.26 vol) over 15 minutes. During the quenching process, the internal temperature is kept at −10 to 15° C. and nitrogen is used to dilute generated hydrogen. After the addition, the mixture is stirred at 20° C. (reaction control) for 0.5 h. The granular residue is filtered and washed with THF (3×1 vol). The combined filtrate is concentrated to 2 vol (300 mmHg, reaction control set at 40° C.). Heptane (6 vol) is added, and the mixture is reduced to 6 vol. The mixture is allowed to ramp to 20° C. over 1 h and then chilled at 10° C. for 30 min. The solid is collected by vacuum filtration, washed with heptane (1 vol), dried at 50° C., 10-15 in Hg vac to a constant weight. Example 3 Preparation of (4-bromo-2-methylphenoxy)(tert-butyl)dimethylsilane [0144] [0145] To a slurry of o-cresol (1 mol, 108 g) and DMAP (1.25 eq, 1.25 mol, 152 g) in toluene (0.43 L) is added tert-butyldimethylsilyl chloride (1.25 eq, 1.25 mol, 375 g of a 50% solution in toluene) at such a rate that the reaction temperature is maintained between 10 and 15° C. The thick slurry is stirred at rt for 5 h, then treated at rt with water (0.29 L). The resulting 2-phase system is stirred for 5 min, then treated with 1N hydrochloric acid (0.12L). After 5 min, the two clear, colorless layers are separated. The aqueous layer is removed and the organic layer is washed with water (0.29 L). The organic layer is washed with 1N sodium hydroxide (0.14 L) for 5 min and the layers separated. The organic layer is washed with water (0.15 L), then evaporated to give a nearly colorless oil. [0146] Stage 2: The neat product of stage 1 (1.0 mol, 223 g) is added in a slow stream to a pre-heated (25° C.) slurry of N-bromosuccinimide (0.96 eq, 0.96 mol, 171 g) in acetonitrile (0.90 L) contained in a vessel protected from light and at such a rate that with rt water bath cooling, the reaction temperature is maintained at 20-25° C. The reaction typically takes 0.5-1.5 h for completion. [0147] To the mixture is added heptane (0.67 L) and water (0.67 L) to produce two clear layers. The product-containing upper layer is separated and washed with water (0.67 L). The resulting organic layer is freed of solvent by rotary evaporator and the resulting oil is dissolved in toluene (0.20 L) followed by distillation of toluene. The drying process is repeated to produce a pale yellow oil (92-95%). Example 4 Preparation of 5-{[(4-[tert-butyl(dimethyl)silyl]oxy}-3-methylphenyl)thio]methyl)2-[2-fluoro-4-(trifluoromethyl)phenyl]-4-methyl-1,3-thiazole (IX) [0148] [0149] A solution of (4-bromo-2-methylphenoxy)(tert-butyl)dimethylsilane (417 g, 1.38 mol) and MTBE (1.80 L) was stirred and chilled to −30° C., then treated over 10 min with 2M n-BuLi/cyclohexanes (1.16 eq, 1.60 mol, 0.800 L). The solution was allowed to warm to 0° C. and maintained at that temperature until trans-metallation was deemed to be complete. The clear, pale yellow solution was cooled to −15° C., and sulfur (1.0 eq., 1.38 mol, 44.2 g) was added via solid-addition funnel at such a rate that the temperature was maintained between −15 and −10° C. The clear, light yellow solution was stirred at −15° C. until reaction was deemed to be complete (HPLC); then held briefly at −15° C. [0150] During the running of the metallation phase, a separate reactor was charged with {2-[2-fluoro-4-(trifluoromethyl)phenyl]-4-methyl-1,3-thiazol-5-yl}methanol (XIII) (1.20 mol, 350 g), triethylamine (1.08 eq, 1.30 mol, 0.179 L), acetonitrile (1.20 L) and methyl t-butyl ether (0.80 L). The slurry was chilled to −20° C. and methanesulfonyl chloride (1.07 eq, 1.28 mol, 0.097 L) was added such that the reaction temperature was maintained between −20 and −15° C. The mixture was held at −15° C. until stage 1 was complete. [0151] The MTBE solution of the metallation product was added via cannula to the acetonitrile/MTBE slurry of the product of (XII) such that the reaction temperature was maintained between −15 and −12° C. The resulting slurry was allowed to warm to 10° C. over 2.5 h and then was quenched with water (3 L). The layers were separated and the organic layer was washed with water (3 L). The organic layer was filtered through diatomaceous earth and the resulting clear filtrate was freed of a small residual layer of water. The organic solution was evaporated to approximately 1.1 L volume, then treated with ethanol (1. 1L) to initiate precipitation of product. The solid was filtered, and the resulting cake washed with ethanol (3×0.2 L) that was pre-cooled to 10° C. The resulting colorless product was dried in vacuo at 55° C., to a constant mass of 538 g (85%). Example 6 Preparation of 4-[({2-[2-fluoro-4-(trifluoromethyl)phenyl]-4-methyl-1,3-thiazol-5-yl}methyl)thio]-2-methylphenol (XX) [0152] [0153] A slurry of 5-{[(4-{[tert-butyl(dimethyl)silyl]oxy}-3-methylphenyl)thio]methyl)2-[2-fluoro4-(trifluoromethyl)phenyl]-4-methyl-1,3-thiazole (IX) (1.00 mol, 527 g) in ethyl alcohol (1.85 L) was treated at ambient temperature with 5N NaOH (2 eq, 2.00 mol, 0.40 L). The resulting slurry was heated at 40° C. for 3 h, after which time heptane (1.2 L) and water (1 L) were added. The lower layer was separated, cooled to 15° C., then treated with 6N HCl (2.1 eq, 2.1 mol, 0.350 L) causing the product to precipitate. The product was filtered, washed with water (3×0.50 L) and heptane (2×0.40 L), and dried at 55° C. under vacuum to produce a colorless solid, 408.9 g (99%). Example 7 Preparation of 2-{4-[({2-[2-fluoro-4-(trifluoromethyl)phenyl]-4-methyl-1,3-thiazol-5-yl}methyl)thio]-2-methylphenoxy}-2-methylpropanoic acid (XXI) [0154] [0155] To a slurry of 20-40 mesh sodium hydroxide (8 eq ) and acetone (10 vol) was added 4-[({2-[2-fluoro-4-(trifluoromethyl)phenyl]-4-methyl-1,3-thiazol-5-yl}methyl)thio]-2-methylphenol (XX) (1 eq, 1 wt), and the resulting slurry was stirred at 32° C. for 3 h. A solution of 1,1,1-trichloro-2-methyl-propanol hydrate (1.7 eq) in acetone (5 vol) was added dropwise over 60 min during which the temperature was allowed to rise and was maintained between 36 and 38° C. The reaction mixture was allowed to cool to rt and the volume was reduced in vacuo to ¼-½ of the total volume. Methyl-t-butylether (10 vol) was added, and 1N hydrochloric acid (10 vol) was added at such a rate as to keep the temperature under 25° C. The organic layer was washed with water (2×4 vol), dried over sodium sulfate (0.1-0.5 wt), filtered, and concentrated to 5 volumes. The solution was heated to approximately 50° C. and heptane (3.5 vol) was added slowly. The solution was then heated to reflux temperature and additional heptane (3.5 vol) was added at such a rate as to maintain the temperature above 55° C. The solution was then distilled at atmospheric pressure to 7 volumes. The solution was cooled to 70° C. over 30 min, during which time the product begins to crystallize. The reaction mixture was then cooled to 20° C. over 30 min. Heptane (1 vol) was added and the slurry is stirred for 15 min at 20° C. The solid was filtered and washed with heptane (2 vol). The off-white solid was returned to the reactor and slurried in 5 vol of heptane. The slurry was heated to 60° C. over 20 min and held at 60° C. for 10 min. The slurry is cooled back to 15° C. over 30 min, and the resulting solid was collected by filtration, washed with heptane (1 vol) dried in vacuo at 50° C., to constant mass (511 g, 70%). Example 8 Preparation of 2-{4-[({2-[2-fluoro-4-(trifluoromethyl)phenyl]-4-methyl-1,3-thiazol-5-yl}methyl)thio]-2-methylphenoxy}-2-methylpropanoic acid [0156] [0157] A slurry of 5-{[(4-[tert-butyl(dimethyl)silyl]oxy}-3-methylphenyl)thio]methyl}-2-[2-fluoro-4-(trifluoromethyl)phenyl]-4-methyl-1,3-thiazole (15.8 g) and sodium hydroxide (5.6 g) in acetone (120 mL) was stirred 45 min at 30° C. to effect quantitative conversion to 4-[((2-[2-fluoro-4-(trifluoromethyl)phenyl]-4-methyl-1,3-thiazol-5-yl)methyl)thio]-2-methylphenol. To the latter slurry was added dropwise over 15 min at 30-40° C. a solution of chlorotone hydrate (9.1 g) and acetone (30 mL). The resulting slurry was stirred at 35° C. for 2 h, additional chlorotone hydrate (1.9 g in 5 mL acetone) was added, and the mixture was stirred at 35° C. until ≧97% conversion was achieved. The resulting slurry was evaporated at reduced pressure to approximately one-third volume then diluted with water (100 mL) and MTBE (200 mL). To this-mixture was added 3N HCl until a pH of approximately 1 was reached. The two layers were separated and the organic solution washed with water (100 mL). The organic solution was evaporated at reduced pressure to a volume of approximately 75 mL, heptane (125 mL) was added, and the volume was reduced to approximately 75 mL. Heptane (100 mL) was added and the solution was cooled to 20° C. to effect crystallization of 2-{4-[({2-[2-fluoro-4-(trifluoromethyl)phenyl]-4-methyl-1,3-thiazol-5-yl}methyl)thio]-2-methylphenoxy}-2-methylpropanoic acid. The product was filtered, washed with heptane (3×100 mL), then dried at 55° C. in a vacuum oven to achieve a constant mass of 10.0 g (66%). The product is identical (HPLC and NMR) to that obtained by the stepwise process.

The present invention relates to a process for the preparation of certain chemical compounds. In particular, the present invention relates to a method for the preparation of compounds that have been shown to activate human peroxisome proliferator activated receptors (“hPPARs”). The present invention also relates to certain chemical compounds useful as intermediates in the preparation of hPPAR active compounds.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printing method and a cloth feeding drum for holding a cloth on which ink jet printing is to be carried out in accordance with such ink jet printing method. Further, the present invention also relates to an ink jet printing apparatus including the above-mentioned cloth feeding drum. 2. Description of the Prior Art In recent years, ink jet coloring has been receiving attention for its use since it can produce fine and delicate patterns. In such ink jet coloring method, an ink jet nozzle sprays ink droplets toward the surface of a cloth to form a pattern thereon, and then such printed coloring substance is fixed and undergoes a coloring treatment. In this connection, one of the most important technical steps in the ink jet coloring process is the ink jet printing step, namely the step of spraying ink droplets onto a cloth surface. Concretely stated, the ink jet printing is carried out by spraying ink droplets from a printing nozzle N onto the surface of a cloth which is held by an intermittently rotating cloth feeding drum, as shown in FIG. 13. The spraying operation is controlled by instructions from a control section P. In such arrangement, the cloth is normally held with a prescribed tension by support pins mounted around drum wheels which are provided at the opposite end portions of the cloth feeding drum, respectively. Such a structure is also disclosed in Laid-Open Patent Application No. SHO 58-109673 and Laid-Open Utility Model Application No. HEI 2-149790 and the like. However, with such prior art cloth feeding drums, it is not always possible to achieve satisfactory results due to the problem resulted from the tension applied to the cloth in the widthwise direction thereof. Further, the operations of piercing the cloth with the support pins and then removing such support pins from the cloth are also not possible to achieve satisfactory results. The reasons which cause such unsatisfactory results are described below. First, with regard to the tension applied to the cloth along the widthwise direction thereof, the following reasons can be mentioned. In order to accurately form fine and delicate patterns with ink jet printing, the distance between the ink jet nozzle and the cloth surface must be kept constant while the nozzle head is moving along the width of the cloth, and the cloth printing surface must be substantially flat. However, the cloth to be introduced into the printing process has distortion and wrinkles which have been formed in the previous process. Therefore, at the time of printing, it is necessary to apply appropriate tension to the cloth which is held by the support pins on the cloth feeding drum for stretching the wrinkles. Further, after printing, the ink that has been applied to the cloth causes the cloth to swell up due to its moisture, thereby also forming wrinkles. Therefore, it is also necessary to apply appropriate tension to the cloth even after printing in order to prevent such wrinkles or the like from being formed. For these reasons, it is not possible to achieve sufficient results only by simply applying a fixed tension to the cloth. In other words, in order to obtain sufficient results, it becomes necessary to change the degree of tension for each of the step of introducing the cloth, the step of performing the ink jet printing onto the cloth and the step after printing in which the cloth is likely to swell up. In other words, it is necessary for the degree of tension applied to the cloth to be adjusted or changed in accordance with the degree of the rotation of the cloth feeding drum. Moreover, it is also preferred that the manner and degree for applying tension to a cloth are selected in accordance with the type of cloth, taking into account such factors as the material, the thickness, the structure and the standard of such a cloth. Next, with regard to the operations of piercing support pins into a cloth and removing the support pins from the cloth, the following reasons can be mentioned. At the time of ink Jet printing, a cloth is introduced onto an introducing region X of the cloth feeding drum, and then the operation of piercing the cloth with the support pins is carried out at the introducing region X. However, with prior art cloth feeding drums, when the cloth is pierced by the support pins at the introducing region X, the support pins pierce the cloth surface in a slanting direction (See FIG. 1). Then, as the cloth feeding drum rotates, the support pins gradually pass through the cloth. Thereafter, when the support pins are perpendicular to the cloth, the cloth becomes held by the base portions of the support pins. For this reason, the operation of piercing the cloth with the support pins can not be carried out smoothly. Furthermore, during the piercing process from the moment when the support pins begin to pierce the cloth until the moment when the cloth reaches the base portions of the support pins at the time the support pins become perpendicular to the cloth, the holding strength for the cloth by the support pins is weak and this results in an extremely unstable condition. On the other hand, when the cloth is to be separated from the cloth feeding drum at the separating region Z, an operation is carried out to pull the cloth off the support pins. In this case, as the cloth feeding drum rotates, the support pins are slowly pulled out from the cloth with rubbing against the cloth. Finally, the support pins are removed from the cloth at the moment when the support pins are at a maximum slant with respect to the cloth surface and then the tips thereof are pulled out from the cloth (See FIG. 2). For this reason, the support pins can not be smoothly pulled out of the cloth. In other words, during the separation process from the state in which the cloth is pierced by the base portions of the support pins until the state in which the support pins are completely removed from the cloth, the cloth is not sufficiently held by the support pins, which gives an extremely unstable holding condition for the cloth. Therefore, in the prior art cloth feeding drums, it is not possible to hold a cloth stably on the cloth feeding drums, since the tension applied in the widthwise direction of the cloth is insufficient and the operations of piercing and removing support pins into and from a cloth can not be carried out smoothly due to the reasons as described in the above. When such unstable holding conditions exist, it is not possible to maintain a fixed uniform distance between the ink jet nozzle and the printing surface of the cloth while the ink jet nozzle is moving along the widthwise direction of the cloth. Further, such unstable holding condition also causes a deterioration in the structure of the cloth and gives rise to distortions or wrinkles or the like. Furthermore, the cloth feeding speed also changes, and this will also produce distortions in the pattern printed on the cloth. SUMMARY OF THE INVENTION This invention is made in view of the problems of the prior art cloth feeding drums as described above. Accordingly, it is an object of the present invention to provide an ink jet printing method which enables distortion-free patterns to be accurately printed onto a cloth. It is another object of the present invention to provide a cloth feeding drum which enables distortion-free patterns to be accurately printed onto a cloth. It is the other object of the present invention to provide a cloth feeding drum which enables piercing of a cloth with support pins and removal of such support pins from the cloth to be carried out smoothly. It is a further object of the present invention to provide a cloth feeding drum which enables the degree of stretching tension applied to the widthwise direction of a cloth to be changed or adjusted. In order to achieve these objects, the inventors of the present invention repeated experiments, and as a result, the inventors have found that the problems of the prior art could be eliminated by moving the support pins in the axial and/or radial directions of the cloth feeding drum, and this knowledge was then used by the inventors to accomplish the present invention. Therefore, the present invention is directed to a method of carrying out ink jet printing, which comprises the steps of introducing a cloth on which ink jet printing is to be carried out onto a cloth feeding drum having a plurality of support pins for holding the cloth on the cloth feeding drum; and moving the support pins in the radial direction of the cloth feeding drum at least when the cloth is introduced onto the cloth feeding drum. In this case, the support pins are moved so as to protrude above the surface of the cloth feeding drum to pierce the cloth with the support pins. Further, the support pins are also moved so as to retract below the surface of the cloth feeding drum when the cloth is removed from the cloth feeding drum. According to the method as described above, the cloth is pierced with the support pins which protrude above the surface of the cloth feeding drum from the inside thereof when the cloth is introduced onto the cloth feeding drum, such operation of piercing the cloth with the support pins can be carried out smoothly. The method of carrying out ink jet printing according to the present invention may further comprise the step of moving the support pins in the axial direction of the cloth feeding drum to apply a tension to the cloth held on the cloth feeding drum after the cloth is introduced onto said cloth feeding drum. According to this method, it is possible to apply an appropriate tension to the cloth for stretching wrinkles or the like that have been formed on the cloth during the previous step. As a result, ink Jet printing operation can be carried out onto such stretched cloth. Further, wrinkles or the like which have been produced when the ink jet printing is being carried out can also be stretched. Another aspect of the present invention is directed to a method of carrying out ink jet printing, which comprises the steps of holding a cloth on which ink jet printing is to be carried out onto a cloth feeding drum having a plurality of support pins using the support pins; and carrying out ink jet printing while the support pins are being moved in the axial direction of the cloth feeding drum so as to apply a tension to the cloth. Further, the other aspect of the present invention is also directed to a cloth feeding drum for use in ink jet printing. The cloth feeding drum includes a drum having a plurality of support pins for holding a cloth on which ink jet printing is to be carried out on the drum; and a mechanism provided within the drum for moving the support pins in the radial direction of the drum. In this case, it is preferred that the moving mechanism is adapted to be actuated at least when the cloth is introduced onto the drum. Further, it is also preferred that the moving mechanism is adapted to move the support pins in such a manner that the support pins protrude above the surface of the drum to pierce the cloth with the support pins. Furthermore, the other aspect of the present invention is directed to a cloth feeding drum for use in ink jet printing. The cloth feeding drum includes a drum having a plurality of support pins for holding a cloth on which ink jet printing is to be carried out; and a mechanism provided within the drum for moving the support pins in the axial direction of the drum so as to apply a tension to the cloth in the widthwise direction thereof. In this case, it is preferred that the moving mechanism is adapted to be actuated after the cloth is introduced onto the drum. Further, it is also preferred that the cloth feeding drum further includes a mechanism for adjusting the moving amount of the support pins. Other aspect of the present invention is also directed to another cloth feeding drum for use in Ink jet printing. This cloth feeding drum includes a drum having a plurality of support pins for holding a cloth on which ink jet printing is to be carried out on the drum; a first mechanism provided within the drum for moving the support pins in the radial direction of the drum; and a second mechanism provided within the drum for moving the support pins in the axial direction of the drum. In this case, it is preferred that the first mechanism is actuated at least when the cloth is introduced onto the drum, and the second mechanism is actuated after cloth is introduced onto the drum. Further, it is also preferred that the cloth feeding drum further comprising a third mechanism for adjusting the moving amount of the support pins moved by the first and/or second mechanisms. The present invention is also directed to an ink jet printing apparatus. This ink jet printing apparatus includes a rotatable cloth feeding drum having a plurality of support pins for holding a cloth on which ink jet printing is to be carried out on the cloth feeding drum; a nozzle for spraying ink onto the cloth held by the support pins to perform the ink jet printing, the nozzle being movable relative to the cloth feeding drum along the axial direction thereof; and a mechanism for applying appropriate tension to the cloth in the widthwise direction of the cloth while the ink jet printing is being carried out. In this case, it is preferred that the tension applying mechanism is adapted to move the support pins provided in at least one of the opposite end portions in the axial direction of the cloth feeding drum. The tension applying mechanism is preferably formed from a first cam provided within the cloth feeding drum for moving the support pins in the axial direction of the cloth feeding drum. Further, it is also preferred that the ink jet printing apparatus further comprises a mechanism for adjusting the moving amount of the support pins moved by the tension applying mechanism in the axial direction of the cloth feeding drum. Furthermore, this ink jet printing apparatus may further includes another mechanism for moving the support pins in the radial direction of the cloth feeding drum. Preferably, this mechanism for moving the support pins in the radial direction of the cloth feeding drum is adapted to protrude the support pins above the surface of the cloth feeding drum to pierce the cloth with the support pins at least when the cloth is introduced onto the cloth feeding drum and retract the pins into the cloth feeding drum to remove the pins from the cloth when the cloth is released from the cloth feeding drum. Further, it is also preferred that the mechanism for moving the support pins in the radial direction includes a second cam provided within the cloth feeding drum for moving the support pins in the radial direction of the cloth feeding drum. Moreover, it is also preferred that the ink jet printing apparatus further comprises a mechanism for adjusting the moving amount of the support pins moved by the mechanism in the radial direction of the cloth feeding drum. Other objects, structures and functions of the present invention will become apparent when the following description of the preferred embodiments will be considered in conjunction with the appended drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an illustration which shows a relationship between a cloth and support pins at a cloth introducing region X of a cloth feeding drum; FIG. 2 is an illustration which shows a relationship between the cloth and the support pins at a cloth separating region Z of the cloth feeding drum; FIG. 3 is an overall view of the cloth feeding drum; FIG. 4 is an enlarged view of a left half portion of the cloth feeding drum according to the present invention; FIG. 5 is a cross sectional view which shows a first embodiment of a driving means provided in the cloth feeding drum according to the present invention; FIG. 6 is a cross sectional view of an up and down direction movement means of the driving means of the first embodiment, which is viewed from the axial direction of the cloth feeding drum; FIG. 7 is a perspective view of a first cam used in the driving means; FIG. 8 is an illustration for explaining the relationship between the up and down movement of the support pins and the shape of a second cam of the driving means according to the present invention; FIG. 9 is an illustration for explaining the relationship between the traces of the sideways movement of the support pins and the traces of the up and down movement of the support pins. FIG. 10 is an illustration which shows a second embodiment of the driving means of the cloth feeding drum according to the present invention; FIG. 11 is an illustration of an up and down direction movement means of the driving means of the second embodiment, which is viewed from the axial direction of the cloth feeding drum; FIG. 12 is an illustration which shows a sideways movement adjusting means of the second embodiment, which is viewed from the axial direction of the cloth feeding drum; FIG. 13 is an illustration which shows support pins mounted on a cloth feeding drum of prior art apparatuses; and FIG. 14 is an illustration which shows support pins provided in the cloth feeding drum according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to the appended drawings, a detailed description of the preferred embodiments will now be given below. FIG. 3 shows an overall view of a cloth feeding drum. As shown in this drawing, the cloth feeding drum is an apparatus which rotates continuously so as to achieve intermittent feeding of a cloth F which is held on a drum surface thereof. In order to accomplish such operation, the cloth feeding drum comprises a drum D2 having opposite end portions and drum wheels D1, D1 provided on the opposite end portions of the drum D2, respectively. A driving apparatus for driving the cloth feeding drum is accommodated within the drum assembly of the drum D2 and drum wheels D1, D1. In the cloth feeding drum, there are provided a plurality of support pins 1. These support pins 1 are arranged in the drum wheels D1, D1, respectively, along the roughly circumferential direction thereof with predetermined intervals. Further, in the respective drum wheel D1, these support pins 1 are adapted to be freely movable in the radial direction (hereinbelow, referred to as the up and down direction) through holes 1A formed on the drum wheel D1. Namely, each of the support pins can be moved above and below the surface of the drum wheel D1 through the respective corresponding hole 1A. Furthermore, these support pins 1 are also adapted to be movable in the axial direction of the cloth feeding drum within the holes 1A, respectively (hereinbelow, referred to as the sideways direction). For this purpose, the holes 1A through which the support pins 1 be moved in the up and down directions are formed into a slit-like shape extending in the axial direction of the cloth feeding drum, respectively, which allow the support pins 1 to be movable in the sideways direction of the cloth feeding drum in addition to the up and down directions. As is further shown in FIG. 3, rotating brushes 12 are provided to push the opposite sides of the cloth F against the support pins 1 of the respective drum wheels D1, D1. FIG. 4 is an enlarged view of the left half portion of the cloth feeding drum shown in FIG. 3. From this drawing, it can be understood that the support pins 1 are arranged within the slits 1A at different positions along the longitudinal direction of the respective slit 1A. FIG. 5 is a cross-sectional view of the first embodiment of the cloth feeding drum of the present invention, and it shows a part of a driving mechanism disposed within the respective drum wheel D1 for moving the support pins 1. The driving mechanism includes an up and down movement means (which is also referred to as a first means in claims) for moving the support pins 1 in the up and down direction and a sideways movement means for moving the support pins 1 in the sideways direction (which is also referred to as a second means or a tension applying means in claims). FIG. 6 is a cross-sectional view of the up and down movement means shown in FIG. 5, which is viewed from the axial direction of the cloth feeding drum. As stated in the above, the drum wheels D1, D1 are provided on the opposite end portions of the drum D2, respectively. In each of the drum wheels D1, D1, there is formed a space in which the driving mechanism for moving the support pins 1 is disposed. The drum wheels D1, D1 are adapted to be rotated in accordance with rotation of a support axle 11. Namely, since these drum wheels D1, D1 are fixedly coupled to the drum D2 which is fixed to the support axle 11 through a boss 11A as shown in FIG. 5, they are rotated in accordance with the rotation of the support axle 11. In more details, a motor (not shown in the drawings) is used to rotate the support axle 11, and this causes the drum D2 which is fixedly mounted to the support axle 11 to be rotated. In accordance with the rotation of the drum D2, the drum wheels D1, D1 rotate together. Hereinafter, the structure and operation of the sideways movement means for moving support pins 1 in the left and right direction (i.e., the sideways direction or the axial direction of the drum) will be described. As stated in the above, the support pins 1 are used to support the cloth F on the surfaces of the drum wheels D1, D1. Each of the support pins 1 is screwed into the top of a rod-shaped support pin movement body 2 so as to extend therefrom. Therefore, the support pin 1 is freely detachable from the support pin movement body 2. Further, the support pin movement body 2 is inserted into a hollow passage formed in a sideways movement member 3 so as to be freely slidable in the up and down direction with respect to the sideways movement member 3. In this regard, it should be noted that the support pin movement body 2 and the sideways movement member 3 constitutes an assembly. The assembly is also used as a part of the up and down direction movement means. Accordingly, in each of the drum wheels D1, D1, a plurality of such assemblies of which number is the same as the number of the support pins 1 provided in one drum wheel D1 are arranged in the circumferential direction of the respective drum wheel D1, and each of the assemblies is operatively associated with each support pin 1. Therefore, hereinafter, a description is made with reference to one of these assemblies. The sideways movement member 3 is disposed within a space 4 formed inside the drum wheel body of the respective drum wheel D1 in such a manner that the sideways movement member 3 is able to slidably move in the sideways direction within the space 4. Provided between the sideways movement member 3 and an inner wall of the drum wheel D1 is a spring S2 which normally biases the sideways movement member 3 toward the left, as shown in FIG. 5. Further, the sideways movement member 3 includes an extending portion 31 which is in slidable abutment with a cam surface 8A of a first cam 8, and as a result of this abutment, the sideways movement member 3 can be moved in the sideways direction in accordance with the shape of the cam surface 8A as shown by the arrow in FIG. 5. As shown in FIG. 7, the first cam 8 is formed into a disk-like shape having an inner peripheral portion which acts as the cam surface 8A. Further, the cam 8 is fixed to an outer axle 10 through a fixing member 81 in such a manner that they form an integral body. The outer axle 10 is provided around the support axle 11. In this regard, it should be noted that while the support axle 11 rotates, the outer axle 10 does not rotate. Namely, the outer axle 10 remains stationary relative to the support axle 11 even if the support axle 11 rotates. According to the structure as described above, when the drum wheels D1, D1 rotate, the sideways movement members 3 also rotate together therewith, and while this rotation is being carried out, the extending portion 31 of each of the sideways movement members 3 slidably moves on the cam surface 8A which remains stationary. Therefore, according to the rotation of the drum wheels D1, D1, some of the sideways movement members 3 are moved in the sideways direction (i.e., the axial direction) against the biasing force of the respective spring S2 in accordance with the shape of the cam surface 8A of the first cam 8. When the sideways movement member 3 is moved in the sideways direction, the support pin movement body 2 which lies inserted within the hollow passage of the sideways movement member 3 is also moved in the sideways direction, and this in turn causes the support pin 1 mounted to the support pin movement body 2 to also move in the same way in the sideways direction within the slit 1A. In this connection, by replacing the cam 8 with other cam having a different cam surface 8A, it is possible to change the motion of the support pin 1 in the sideways direction as desired. This means that it is possible to adjust the amount of the sideways movement of the support pin 1 appropriately by changing the cam 8. When the first cam 8 is to be replaced, one side of the drum wheels D1, D1 (the left side in the drawings) is temporarily opened up and the fixing means 81 is detached from the outer axle 10 to release the fixed connection between the first cam 8 and the outer axle 10. Thereafter, the first cam 8 is pulled to the left along the outer axle 10 to remove the first cam 8 from the outer axle 10. Therefore, the replacement of the first cam 8 can be easily carried out. Hereinbelow, the structure and operation of the up and down movement means for moving support pins 1 in the up and down direction will be given. As shown in the drawings, each of the support pin movement bodies 2 which is inserted through the hollow passage of the sideways movement member 3 includes a lower extending portion having a bottom surface which is in slidable abutment with a cam surface 9A of a second cam 9. Provided between the support pin movement body 2 and the sideways movement member 3 is a spring S1 which normally biases the support pin movement body 2 toward the cam surface 9A of the second cam 9 as illustrated in FIG. 5. The second cam 9 is formed into a disk-like shape having a circumferential surface which acts as the cam surface 9A. The second cam 9 is fixed to the outer axle 10 which is disposed around the support axle 11 through a fixing means 91 in such a manner that the second cam 9 and the outer axle 10 form an integral body. In this connection, it should be understood that because the outer axle 10 does not rotate and remains stationary relative to the support axle 11, the second cam 9 is also in a motionless state even if the drum wheels D1, D1 rotate. In the same manner as was described above for the first cam 8, when the second cam 9 is to be replaced, one side of the drum wheels D1, D1 (the left side in the drawings) is temporarily opened up and the fixing means 91 is detached from the outer axle 10 to release the fixed state between the second cam 9 and the outer axle 10. Thereafter, the second cam 9 is pulled to the left along the outer axle 10 to remove the second cam 9 from the outer axle 10. Therefore, the replacement of the second cam 9 can also be easily carried out. According to the structure described above, when the drum wheels D1, D1 rotate, the support pin movement bodies 2 also rotate together therewith. As this rotation takes place, the bottom surface of the lower extending portion of each of the support pin movement bodies 2 which is in slidable abutment with the cam surface 9A of the second cam 9 causes the support pin movement body 2 to move in the up and down direction against the biasing force of the spring S1 according to the shape of the cam surface 9A of the second cam 9. When the support pin movement body 2 moves up and down, the support pin 1 which is mounted to the top of the support pin movement body 2 also moves up and down together with support pin movement body 2 through the slit 1A. FIG. 8 is a cross-sectional view illustrating the relationship between the shape of the cam surface 9A of the second cam 9 and the up and down movement of the respective support pins 1. In this connection, it should be noted that the cam surface 9A has the shape as illustrated in FIG. 8. Specifically, the second cam 9 is formed into a substantially disk-like shape having a roughly semi-circular large diameter section and a roughly semi-circular small diameter section which are Joined together to form the cam surface 9A. Therefore, two transition portions are formed on the cam surface 9A at a portion running from the large diameter section to the small diameter section and another portion running from the small diameter section to the large diameter section. The positions of these transition portions are set so as to correspond to the cloth introducing region X and the cloth separating region Z, respectively. In the above structure, the support pins 1 mounted to the support pin movement bodies 2 which are in abutment with the cam surface 9A of the small diameter section of the second cam 9 are held below the surface of the drum wheel D1 due to the biasing force of the respective spring S1, that is they are held in the base level position. On the other hand, the support pins 1 mounted to the support pin movement bodies 2 which are in abutment with the cam surface 9A of the large diameter section of the second cam 9 are held above the surface of the drum wheel D1 against the biasing force of the spring S1, that is they are held in the positive position. Further, the support pins 1 mounted to the support pin movement bodies 2 which are in abutment with the transition portions of the cam surface 9A of the second cam 9 are being gradually protruded from the inside of the drum wheel or retracted into the drum wheel, respectively, according to the rotation of the drum wheels D1, D1. Now, FIG. 9 shows the relationship between the sideways motion of the support pins 1 and the up and down motion of the support pins 1. As see from the drawing, for the movement of the support pins 1 in the sideways direction, when the cloth F reaches the introducing region X for introducing the cloth F onto the drum wheels D1, D1, the support pins 1 begin to move from their base level positions to positive positions in the axial direction of the drum wheels D1, D1 due to the biasing force of the respective spring S2. Namely, the width between pairs of support pins 1 arranged in the drum wheels D1 and D1 on either end of the drum D2 is increased, thereby applying an increased tension to the cloth in the widthwise direction thereof to stretch out any wrinkles or the like that have been produced on the cloth in the previous step. The printing operation, namely spraying of ink onto the cloth is carried out under this condition. After the cloth F which is held on the cloth feeding drum passes a portion of the drum where the cloth is sprayed with ink droplets from the nozzle (hereinafter, referred to as printing region Y), the cloth F is likely to swell up to produce wrinkles due to the moisture of the ink. In order to stretch such wrinkles of the cloth F, it is preferred that the support pins 1 further move to an even greater positive position than that reached at the introducing region X for further increasing a tension applied to the cloth. Namely, the width between the pairs of support pins arranged in the drum wheels D1 on either end of the drum D2 is further increased to stretch the cloth F, thereby eliminating any wrinkles or the like that are formed in the cloth F due to the ink applied thereto. Next, as the cloth F further moves to the separating region Z and separates from the cloth feeding drum, the support pins 1 are released from the cloth F and return to their original base level positions against the biasing force of the respective spring S2. In this connection, it should be noted that the cam surface 8A of the first cam 8 is formed into a shape that guarantees such movement of the support pins 1 in the sideways direction. Hereinafter, a description is made with regard to the up and down movement of the support pins 1. The support pins 1 are in the positive positions (i.e., protrude above the surface of the drum wheels D1, D1) from the introducing region X until the separating region Z, but upon passing the separating region Z, the support pins 1 return to their original base level position (i.e., beneath the surface of the drum wheels D1, D1). Hereinbelow, a detailed description of the movement of the support pins 1 will be given. First, in accordance with the rotation of the drum wheels D1, D1, the extending portions 31 of the sideways movement members 3 which are housed within the drum wheels D1, D1 also rotate under the condition that they are in slidable abutment with the cam surface 8A of the first cam 8 that remains stationary, whereby the sideways movement members 3 are caused to move in the sideways direction (axial direction of the drum) within the spaces 4, respectively in accordance with shape of the cam surface 8A of the first cam 8. When the sideways movement members 3 move in the sideways direction, the support pin movement bodies 2 which are fitted through the hollow passages of the sideways movement members 3 also move in the same sideways direction, and this causes the support pins 1 to move in the same sideways direction within the slits 1A. On the other hand, with regard to the up and down movement of the support pins 1, such operation as described hereinbelow is carried out in this situation. Namely, since the lower extending portions 22A of the support pin movement bodies 2 are in slidable abutment with the cam surface 9A of the motionless second cam 9, the support pin movement bodies 2 are caused to move in the up and down direction according to the rotation of the drum wheels D1, D1. Then, the support pins 1 which are mounted on the support pin movement bodies 2 are also caused to move together with the support pin movement bodies 2 in the same up and down direction through the slits 1A. In this regard, it should be mentioned that even though the support pin movement bodies 2 move in the same sideways direction as the sideways movement members 3 in accordance with the shape of the cam surface 8A of the first cam 8, such movement only causes the lower extending portions 22A of the support pin movement bodies 2 to move either left or right (i.e., in the sideways direction) within the cam surface 9A of the second cam 9, and therefore such sideways movement does not have any effect on the up and down movement of the support pins 1. Similarly, even though the support pin movement bodies 2 move up and down in accordance with the cam surface 9A of the second cam 9, the support pin movement bodies 2 are able to slide freely within the hollow passage formed in the sideways movement members 3, and therefore such up and down movement does not have any effect on the sideways movement of the support pins 1. In this way, the sideways movement and the up and down movement of the support pins 1 do not interfere with each other, and therefore such movements can be carried out independently. Moreover, by using a first cam 8 having a cam surface 8A which is formed into a uniform shape without any step or slanting portion, it is possible to completely eliminate any sideways movement of the support pins 1. Similarly, by using a second cam 9 having a cam surface 9A which is formed into a uniform shape without any step or slanting portion, it is possible to completely eliminate any up and down movement of the support pins 1. In this way, it is possible to select one of three possible movements for the support pins 1, that is (1) up and down movement and sideways movement; (2) up and down movement only; and (3) sideways movement only. As was described above, the drum wheels D1, D1 are equipped with the up and down movement means and the sideways movement means which operate independently from each other to move the support pins 1. Therefore, when the drum wheels D1, D1 are rotated, such rotation can be used to cause the support pins 1 to move in the up and down direction as well as the sideways direction, or such rotation can be used to selectively move the support pins 1 in either the up and down direction or the sideways direction. Moreover, the movement of the support pins 1 in the sideways direction (including the amount thereof) can be freely changed by changing the shape of the first cam 8, and the movement of the support pins 1 in the up and down direction (including the amount thereof) can similarly be freely changed by changing the shape of the second cam 9. These functions are referred to as the moving amount adjusting means or third means in claims. Hereinbelow, a description of a second embodiment of the present invention will be given below. FIG. 10 shows the second embodiment of the present invention, in which a different type of driving means, namely means for moving the support pins 1, is arranged within the drum wheels D1, D1 of the cloth feeding drum for moving the support pins 1 in the radial direction (i.e., the up and down direction) and the axial direction (i.e., the sideways direction). FIG. 11 is a cross-sectional view of the up and down movement means shown in FIG. 10, which is viewed from the axial direction of the cloth feeding drum. First, the structure and operation of the sideways movement means for moving support pins 1 in the sideways direction will be given. Similar to the first embodiment described above, the second embodiment also includes a plurality of sideways movement members 3 each having a hollow passage formed in the middle thereof, and a plurality of support pin movement bodies 2 which are inserted through the hollow passages of the sideways movement members 3, respectively, to allow each support pin movement body 2 to be slidable relative to the sideways movement member 3 in the up and down direction. The sideways movement member 3 and the up and down movement body 2 constitute an assembly, and a plurality of such assemblies of which number is the same as the number of the support pins 1 provided on the respective drum wheel D1 are arranged in the circumferential direction of the respective drum wheels D1, D1 so as to be associated with the support pins 1. Further, in the same manner as the first embodiment, each of the sideways movement members 3 is fitted into a space 4 formed inside the drum wheel body of the respective drum wheels D1, D1 in such a manner that the sideways movement members 3 are able to move in the sideways direction within the respective space 4. Therefore, the same or corresponding components and elements are indicated by the same reference numerals between the first and second embodiments. Now, the main difference between the first embodiment described above and the second embodiment is that the second embodiment is further equipped with sideways movement width adjusting means (referred as third means or moving amount adjusting means in claims) to enable the amount of movement of the sideways movement members 3 in the sideways direction to be adjusted. Since such sideways movement width adjusting means is provided in each of the sideways movement member 3, the description is made with reference to one of the sideways movement width adjusting means. In this connection, FIG. 12 is a cross-sectional view of the sideways movement width adjusting means, which is viewed from the axial direction of the cloth feeding drum. As shown in FIG. 10, the sideways movement width adjusting means is constructed from an adjustment rod 5 having a plurality of holes 52, a pivotal axis 6 which is inserted through any one of the holes 52 of the adjustment rod 5, and adjustment holes 7 formed in the body of the drum wheel D1 to receive the pivotal axis 6. Further, a fitting groove 51 is formed at a prescribed position in the adjustment rod 5. The end of the extending portion 31 of the sideways movement member 3 is fitted via a pin into the fitting groove 51. Further, as described in the above, the plurality of holes 52 which are spaced at prescribed distances from each other are formed in the adjustment rod 5. The pivotal axis 6 is inserted into any one of these holes 52 to adjust the amount of the displacement of the adjustment rod 5 about the pivotal axis 6. Specifically, in this connection, the adjustment holes 7 are formed in the body of the drum wheel D1 at prescribed intervals corresponding to those of the holes 52 of the adjustment rod 5. Accordingly, by inserting the pivotal axis 6 through any one of the holes 52 in the adjustment rod 5 and fitting the pivotal axis 6 into the corresponding adjustment hole 7, the pivotal axis 6 becomes fixed to serve as a pivot point for the adjustment rod 5. With the pivotal axis 6 as a pivot point, the lower end of the adjustment rod 5 is able to pivot. In this construction, because the pivotal axis 6 can be fixed in any one of the adjustment holes 7 through the corresponding hole 52 in the adjustment rod 5, the distance L between the pivotal axis 6 and the fitting portion of the adjustment rod 5 where the extending portion 31 of the sideways movement member 3 is fitted into the fitting groove 51 can be freely adjusted. Further, in this embodiment, the lower end of the adjustment rod 5 is fitted into a cam groove 8B formed on a circumferential surface of a first cam 8 to enable such lower end to move in the sideways direction by following the path of the cam groove 8B. As is made clear by FIG. 10, when the lower end of the adjustment rod 5 is in engagement with a section V of the cam groove 8B of the first cam 8, it provides the situation in which the cloth holding width provided between a pair of support pins 1 is made narrow, and when the lower end of the adjustment rod 5 is in engagement with a section W of the cam groove 8B of the first cam 8, it provides the situation in which the cloth holding width between the pair of support pins 1 is made wide. In this construction, when the adjustment rod 5 is moved in the sideways direction, the sideways movement member 3 which is coupled thereto through the extending portion 31 also moves sideways, and as a result, the support pin movement body 2 which lies inserted through the hollow passage of the sideways movement member 3 also moves sideways. Next, an explanation is made with reference to the case where the pivotal axis 6 is displaced from the above hole 52 and the corresponding adjustment hole 7 shown in FIG. 10 to a different hole 52 and a corresponding adjustment hole 7 which are positioned far away from the first cam 8. In this case, the distance L from the pivotal axis 6 to the coupling portion between the adjustment rod 5 and the extending portion 31 of the sideways movement member 3 is increased, and this also results in an increase in the distance M from the pivotal axis 6 to the lower end of the adjustment rod 5 which lies within the cam groove 8B (i.e., the rotation radius of the adjustment rod 5). As a result, since the degree of the sideways movement of the sideways movement member 3 is decreased, the degree of the sideways movement of the support pin 1 is also decreased. On the other hand, when the pivotal axis 6 is fixed to a hole 52 and an adjustment hole 7 which are positioned closer to the first cam 8, the distance L and the distance M are decreased. As a result, since the degree of the sideways movement of the sideways movement member 3 is increased, the degree of the sideways movement of the support pin 1 is also increased in the same way. As described in the above, according to the second embodiment, by changing the fitting position of the pivotal axis 6 with respect to a hole 52 of the adjustment rod 5, it is possible to change the rotation radius of the adjustment rod 5, and as a result, it becomes possible to change the sideways movement width of the sideways movement member 3, namely it becomes possible to freely change the sideways movement width of the support pin 1. Next, a description will be given with reference to the up and down movement means of the second embodiment for moving support pins 1 in the up and down direction. In this regard, the up and down movement means of the second embodiment differs from that of the first embodiment. Namely, the lower portion of the support pin movement body 2 is provided with a rail body 21 that forms an integral part therewith, and fitted into this rail body 21 so as to be slidable with respect thereto is an adjustment sliding body 22. Now, in the first embodiment, because only a single cam body is provided as the second cam 9, it is necessary to replace the second cam 9 with another cam in order to change or adjust the up and down movement distance. However, in this second embodiment, there are provided a plurality of second cams 9 each having a cam surface 9A of a different shape. Therefore, when the up and down movement distance of the support pins 1 is to be changed, the adjustment sliding body 22 is moved along the rail body 21 so that the extending portion 22A of the sliding body 22 is put onto cam surface of a different cam. This function is also referred to as the moving amount adjusting means in claims. For example, the extending portion 22A can be moved from the top of the cam 9 to the top of the adjacent cam 9. In this connection, the support pin movement body 2 is normally biased by the spring body S1 toward the cam surface 9A of the second cam 9. Therefore, when the second cam 9 is to be replaced with other cam, the support pin movement body 2 is moved slightly upward against the biasing force of the spring S1 and then moved sideways by means of the slidable engagement between the sliding body 22 and the rail body 21 to put the extending portion 22A of the support pin movement body 2 on the top of the cam surface of the other cam 9. In this regard, it should be understood that if it is desired to replace one or more of the cam bodies of the second embodiment with other cam bodies, the replacement can be performed in the same manner as was described above for the first embodiment. Finally, a comparison will be made between the present invention and the cloth feeding drums of the prior art. In this connection, FIGS. 13 and 14 are illustrations used to compare the relationship between the support pins 1 and a cloth F of a prior art cloth feeding drum with that of the cloth feeding drum according to the present invention. In the case of the prior art cloth feeding drum (FIG. 13), the support pins 1 always protrude above the surface of the cloth feeding drum. However, in the case of the present invention (FIG. 14), the support pins 1 protrude above the surface of the cloth feeding drum over the region where the cloth F is held on the cloth feeding drum, but over the region where the cloth F is not held, the support pins 1 are retracted below the surface of the cloth feeding drum. Namely, the support pins 1 are forced to protrude out above the surface of the cloth feeding drum to pierce the cloth F at the introducing region X for introducing the cloth F onto the cloth feeding drum, and then the support pins 1 are removed from the cloth F and retracted below the surface of the cloth feeding drum at the separating region Z. Therefore, these operations of protruding the support pins 1 to pierce the cloth F and then retracting the support pins 1 to remove the support pins 1 from the cloth F are carried out smoothly. It is to be noted that the present invention is in no way limited to the embodiments described above, and many changes, alterations and/or additions may be made thereto without departing from the scope and spirit of the present invention as defined by the appended claims. For example, even though the up and down movement means for moving the support pins in the up and down direction and the sideways movement means for moving the support pins in the sideways direction of the embodiments described above utilize the cam mechanism as described above, it is also possible to employ electrical driving apparatuses to perform the same or similar functions. Furthermore, even though the cloth holding region of the cloth feeding drum is provided so as to extend about 180 degrees in the embodiments described above, it is possible to use a cloth holding region having any degree desired. As was described above, according to the present invention, the operations of protruding the support pins and retracting the support pins can be carried out smoothly, and thus the present invention makes it possible to provide a cloth feeding drum and an ink Jet printing apparatus having such a cloth feeding drum that can maintain stable holding conditions for a cloth on the cloth feeding drum. Further, ink Jet printing can be carried out onto a cloth under the condition that wrinkles formed thereon are stretched by the applied tension. Furthermore, wrinkles formed during the ink Jet printing operation can also be stretched. Consequently, it is possible to prevent wrinkles and the like from being formed on the cloth. Further, it is also possible to prevent the rotational speed of the cloth feeding drum from being changed, and this makes it possible to effectively obtain accurately printed patterns on a cloth.

A method of carrying out ink Jet printing includes the steps of: introducing a cloth on which ink Jet printing is to be carried out onto a cloth feeding drum having a plurality of support pins for holding the cloth on the cloth feeding drum; and moving the support pins in the radial direction of the cloth feeding drum at least when the cloth is introduced onto the cloth feeding drum. Further, the method may also include the step of moving the support pins in the axial direction of the cloth feeding drum to apply a tension to the cloth held by the support pins on the cloth feeding drum after the cloth is introduced onto the cloth feeding drum. A cloth feeding drum for use in ink jet printing includes a cloth feeding drum having a plurality of support pins for holding a cloth on which ink jet printing is to be carried out on the cloth feeding drum; and a mechanism provided within the cloth feeding drum for moving the support pins in the radial direction of the cloth feeding drum at least when the cloth is introduced onto the cloth feeding drum. The cloth feeding drum may further include a mechanism for moving the support pins in the axial direction of the cloth feeding drum so as to apply a tension to the cloth held by the support pins. These mechanisms are actuated at least when the cloth is introduced onto the cloth feeding drum and after the cloth is introduced onto the cloth feeding drum, respectively.

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a dish-drying and vegetable-cleaning machine, and in particular to a composite machine capable of generating hot air for drying dishes and ozone for cleaning vegetables and fruits. [0003] 2. Description of Prior Art [0004] A dish dryer is a common electric appliance used in the kitchen of a house. The dish dryer is used to dry tableware such as bowls, dishes or the like. If the dishes after washing are not dried completely, the water droplets on the surface of the dishes may wet the environment. As a result, bacteria may propagate to generate mildew. Since the dishes are utensils for containing foods, if the dishes are not cleaned, it may be harmful to the human's body. Thus, the tableware such as bowls and dishes has to be disposed on a dish rack within the dish dryer and the water droplets on the bowls and dishes are dried by hot air, thereby keeping the environment dried and preventing the propagation of bacteria. A common dish dryer includes a machine body, an outer cover for covering the machine body, and a dish rack. A closed space is formed between the outer cover and the machine body for receiving the dishes. An electric heater is provided in the machine body. The hot air generated by the electric heater is circulated in the closed space, whereby the tableware can be sterilized and dried quickly. In this way, clean and sterilized tableware can be used, and the operation of this dish dryer is very convenient. Usually, the tableware is washed in a cleaning trough. As a result, the dish dryer is arranged near the cleaning trough, so that it is convenient for the user to put the washed tableware in the nearby dish dryer for drying. The water droplets collected from the tableware can be drained in the cleaning trough. However, when the dish dryer is not in use, it occupies a lot of space, which is really a problem. [0005] As for the vegetables, not only the freshness, but also the cleanness is needed. Especially, the vegetables and fruits used for uncooked vegetable salad including leaf vegetables (e.g. parsley, spinach), fruit vegetables (e.g. tomato, cucumber) or fruits (muskmelon, apple), since these vegetables and fruits are eaten uncooked, no sweat dirt, insect eggs or pesticide can remain on the surfaces of the vegetables and fruits. The original way of cleaning the vegetables is as follows: vegetables are first received in a vegetable basket and the vegetable basket is dipped into the water of the cleaning trough, so that the flowing water rinses away the sweat dirt, insect eggs and remaining pesticide on the surfaces of the vegetables. Alternatively, a machine is developed for cleaning vegetables, which includes a body with an open top surface, and a water-stirring tray provided in the bottom of the body. Water is filled in the body and the vegetables and fruits are put in an upper portion of the body. The water-stirring tray is powered to stir the water, whereby the whirling water can clean the vegetables and fruits. However, using the flowing water in the cleaning trough to rinse the vegetables and fruits needs a lot of water, which causes the increase in the cost. On the other hand, the vegetable-cleaning machine has a lot of components and is complicated in structure, which also raises the cost and the subsequent maintenance. [0006] Therefore, in order to solve the above-mentioned problems, the present Inventor proposes a reasonable and novel structure based on his deliberate research and expert experiences. SUMMARY OF THE INVENTION [0007] The present invention is to provide a composite machine for drying dishes and cleaning vegetables and fruits, thereby drying dishes or cleaning vegetables and fruits by ozone. With this arrangement, the utility rate of the machine can be increased, and the space can be used more effectively. Further, the cost can be reduced and the maintenance is easy. [0008] The present invention provides a composite machine for drying dishes and cleaning vegetables and fruits, which includes a dish-drying body; an ozone generator mounted in the dish-drying body, the ozone generator having an air-delivering pipe; and a cover selectively covering the dishes or allowing the vegetables and fruits to be received therein, one end of the air-delivering pipe being disposed in the cover. [0009] The present invention provides a composite machine for drying dishes and cleaning vegetables and fruits, which includes a dish-drying body; an ozone generator mounted in the dish-drying body, the ozone generator having an air-delivering pipe; a cover selectively covering the dishes or allowing the vegetables and fruits to be received therein, one end of the air-delivering pipe being disposed in the cover; and a switching element fixed in the dish-drying body and switchable to be electrically connected to the dish-drying body or the ozone generator, wherein the dish-drying body generates hot air to dry the dishes when the switching element is electrically connected to the dish-drying body, and the ozone generator generates ozone to clean the vegetables and fruits when the switching element is electrically connected to the ozone generator. [0010] The present invention provides a composite machine for drying dishes and cleaning vegetables and fruits, which includes a dish-drying body for allowing the dishes or the vegetables and fruits to be disposed therein; an ozone generator mounted in the dish-drying body, the ozone generator having an air-delivering pipe; and a switching element fixed to the dish-drying body and switchable to be electrically connected to the dish-drying body or the ozone generator, wherein the dish-drying body generates hot air to dry the dishes when the switching element is electrically connected to the dish-drying body, and the ozone generator generates ozone to clean the vegetables and fruits when the switching element is electrically connected to the ozone generator. [0011] The present invention has advantageous features as follows. After washing, the water droplets on the dishes are dried by the hot air to keep the environment clean and prevent the propagation of bacteria. When the dish dryer is not in use, it can also generate ozone to clean the vegetables and fruits. Thus, the idle time of the composite machine is reduced, thereby increasing the utility rate and the using the space more effectively. With the strong sterilizing effect of the ozone, the ozone is dissolved in the water to remove the dirt and bacteria remaining on the vegetables and fruits. Thus, it is unnecessary to use a conventional machine of a complicated structure to clean the vegetables and fruits, so that the cost can be reduced and the maintenance is easy. BRIEF DESCRIPTION OF THE DRAWINGS [0012] FIG. 1 is an exploded perspective view of the present invention; [0013] FIG. 2 is a schematic view showing the operating state of the present invention in drying dishes; [0014] FIG. 3 is a schematic view showing the operating state of the present invention in washing vegetables and fruits; [0015] FIG. 4 is a view showing the introduction of ozone by a plurality of pipes in the present invention; and [0016] FIG. 5 is a view showing the storage of the air-delivering pipe according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION [0017] The characteristics and technical contents of the present invention will be described with reference to the accompanying drawings. However, the drawings are illustrative only but not used to limit the present invention. [0018] Please refer to FIG. 1 , which is an exploded perspective view of the present invention. The present invention provides a composite machine for drying dishes and cleaning vegetables and fruits, which includes a dish-drying body 10 , an ozone generator 20 , a cover 30 , a switching element 40 , a tableware basket 50 and a switch 60 . [0019] The dish-drying body 10 includes a base 11 , a circuit board 12 , a hot air generator 13 , a timer 14 , a supporting tray 15 , a drainage valve 16 and a storage portion 17 . The circuit board 12 is fixed in the base 11 and electrically connected to an external power source. The hot air 13 is fixed in the base 11 and electrically connected to the circuit board 12 . The internal components of the hot air generator 13 comprise a heating element 131 and a fan 132 for blowing the heating element 131 . The hot air generator 13 is provided with an air-introducing port 133 located at one side near the fan 132 and an air-exiting port 134 located at one side near the heating element 131 . The surface of the base 11 is provided with a hot air port 111 in communication with the air-exiting port 134 . The timer 14 is exposed to the front surface of the base 11 and electrically connected to the circuit board 12 . The supporting tray 15 is movably received in the base 11 . The drainage valve 16 is provided in the base 11 to correspond to the position of the supporting tray 15 . The storage portion 17 is movably provided in the base 11 . The storage portion 17 comprises a plate 171 and a plurality of posts 172 protruding from the surface of the plate 171 . [0020] The ozone generator 20 is fixed in the base 11 to correspond to the storage portion 17 and electrically connected to the circuit board 12 . The internal components of the ozone generator 20 comprise an air-delivering pipe 21 , an ultraviolet lamp 22 , and a cylinder 23 . The ozone generator 20 is provided with a venting port 24 located at one side near the ultraviolet lamp 22 . The cylinder 23 is positioned to correspond to the ultraviolet lamp 22 and away from the venting port 24 . One end of the air-delivering pipe 21 is connected to the cylinder 23 . The storage portion 17 is provided with a guiding hole 173 at one side near the cylinder 23 . The other end of the air-delivering pipe 21 penetrates the guiding hole 173 to be wound around the posts 172 , so that a certain length of the air-delivering pipe 21 can be wound around the plate 171 . [0021] The cover 30 is made of transparent materials and provided on the dish-drying body 10 . The cover 30 has an accommodating space 31 . A lower portion of the periphery of the cover 30 is provided with an insertion hole 32 and a plurality of exhausting holes 33 . The surface of the cover 30 is formed with a handle 34 . The end of the air-delivering pipe 21 away from the cylinder 23 penetrates the insertion hole 32 and is disposed in the accommodating space 31 . [0022] The switching element 40 is exposed to the front surface of the base 11 and electrically connected to the circuit board 12 . The switching element 40 is switchable to be electrically connected to the dish-drying body 10 and the circuit board 12 or electrically connected to the ozone generator 20 and the circuit board 12 . When the switching element 40 is electrically connected to the dish-drying body 10 , the dish-drying body 10 generates hot air. When the switching element 40 is electrically connected to the ozone generator 20 , the ozone generator 20 generates ozone. [0023] In addition to be switchable between the above-mentioned target components, the switching element 40 can also restrict the countdown time of the timer 14 . The bottom of a knob of the timer 14 has a cam structure 141 . When the switching element 40 is switched to the dish-drying function, the cam structure 141 can rotate freely without any restriction, and the timer 14 can be set arbitrarily. When the switching element 141 is switched to the ozone-cleaning function, the switching element 40 will restrict the rotation of the cam structure 141 , so that the timer 14 can be only set to a certain value. [0024] The tableware basket 50 is provided on the dish-drying body 10 and received in the accommodating space 31 . The tableware basket 50 has a plurality of filtering holes 51 . [0025] The switch 60 is exposed to the front surface of the base 11 and electrically connected to the circuit board 12 . The switch 60 is used to turn on or off the electrical connection between the circuit board 12 and the external power supply. [0026] Please refer to FIG. 2 , which is a view showing the operating state of the present invention in drying dishes. The dishes after washing are put in the tableware basket 50 . Then, the cover 30 covers the dish-drying body 10 . The switching element 40 is operated to electrically connect the dish-drying body 10 and the circuit board 12 , and then the countdown time of the timer 14 is set. Since the rotation 141 of the cam structure 141 will not be restricted, the timer 14 can be set arbitrarily, and usually it takes about one hour to dry the dishes. The switch 60 is turned on to electrically connect the circuit board 12 and the external power supply, thereby activating the hot air generator 13 . The heating element 131 heats up the surrounding air, and the fan 132 blows the hot air through the air-exiting port and the hot air port 111 into the accommodating space 31 . The hot air is circulated in the accommodating space 31 to dry the dishes. The wetted air is exhausted through the exhausting holes 33 . After the countdown time of the timer 14 is finished, the hot air generator 13 stops working. The user can watch the drying condition through the transparent cover 30 . If the water droplets on the dishes are not dried completely, the user resets the timer 14 to continue the operation of the hot air generator 13 . When the dishes are dried completely, the user grips the handle 34 to take off the cover 30 and take the dried dishes out of the machine. The water droplets of the dishes will be collected to the supporting tray 15 through the filtering holes 51 and the opened drainage valve 16 . The supporting tray 15 can be drawn out to remove the accumulated water. [0027] Please refer to FIG. 3 , which is a schematic view showing the operating state of the present invention in cleaning vegetables and fruits. First, the tableware basket 50 is removed from the dish-drying body 10 . The cover 30 is turned upside down to cover the dish-drying body 10 , and fresh water is filled in the accommodating space 31 . The vegetables and fruits to be cleaned are put into the fresh water. The level of the fresh water is not higher than that of the insertion hole 32 and the exhausting holes 33 , thereby avoiding from the overflowing of the water to damage the dish-drying body 10 . The plate 171 is drawn out and the air-delivering pipe 21 is unwound from the posts 172 . One end of the air-delivering pipe 21 penetrates the insertion hole 32 into the water of the accommodating space 31 . The switching element 40 is operated to electrically connect the ozone generator 20 and the circuit board 12 . Since the switching element 40 will restrict the rotation of the cam structure 141 , the timer 14 can be set to a certain value only. Since it would be better to execute the ozone cleaning without exceeding fifteen minutes, the timer 14 is set at most to fifteen minutes. If the timer 14 is originally set to over fifteen minutes, the switching element 40 will be restricted by the cam structure 141 , so that it cannot be switched to the ozone cleaning function. Then, the switch 60 is turned on to electrically connect the circuit board 12 and the external power source, thereby activating the operation of the ozone generator 20 . At this time, the ultraviolet lamp 22 illuminates the surrounding air. With a wavelength in a range of 175 nm to 200 nm, the oxygen molecules in the air will be ionized to form ozone. The formula of ozone is O 3 with a molecular weight of 48, a melting point of 192.7° C., boiling point of −111.9° C. The ozone is slightly dissolvable in the water. The specific weight of ozone is approximately 1.7 times of the air and 1.5 times of the oxygen. The thin ozone has no color and smell and is a nonflammable gas. Low concentration of ozone generates a special smell of grass, while high concentration of ozone exhibits a light blue. In normal temperature between 18° C. and 30° C., ozone will be decomposed into oxygen molecules and oxygen atoms. The chemical property of the oxygen atoms is very active to generate strong sterilizing, deodorizing, and bleaching effects, thereby preventing the propagation of bacteria and mildew. The cylinder 23 drives the ozone into the water through the air-delivering pipe 21 . The air is introduced through the venting hole 24 into the ozone generator 20 to generate more ozone. The ozone is dissolved in the water to remove the sweat dirt, inset eggs and remaining pesticide on the surface of vegetables and fruits. [0028] Please refer to FIG. 4 , which shows the introduction of ozone by a plurality of pipes. The composite machine for drying dishes and cleaning vegetables and fruits further includes an auxiliary air-delivering pipe 25 . One end of the auxiliary air-delivering pipe 25 is connected to the cylinder 23 . The other end of the air-delivering pipe 21 is received in the storage portion 17 . In use, the air-delivering pipe 21 extends into the water, and the auxiliary air-delivering pipe 25 extends into the water to be away from the air-delivering pipe 21 . In this way, the amount and range of ozone dissolved in the water can be increased, so that the effect of cleaning vegetables and fruits can be enhanced. [0029] Please refer to FIG. 5 , which is a view showing the storage of the air-delivering pipe according to another embodiment of the present invention. The storage portion 17 is fixed in the base 11 . The side wall of the base 11 is provided with a through-hole 135 to correspond to the position of the storage portion 17 . The storage portion 17 is a winding disk. One end of the air-delivering pipe 21 is connected to the cylinder 23 , and the other end thereof is received in the storage portion 17 to penetrate the through-hole 135 . In use, the air-delivering pipe 21 penetrates the through-hole 135 to be drawn out of the storage portion 17 . Then, the air-delivering pipe 21 is inserted into the insertion hole 32 and thus extends into the water. After using, the air-delivering pipe 21 is wounded into the storage portion 17 with its distal end protruding from the through-hole 135 for subsequent use. [0030] Although the present invention has been described with reference to the foregoing preferred embodiments, it will be understood that the invention is not limited to the details thereof. Various equivalent variations and modifications can still occur to those skilled in this art in view of the teachings of the present invention. Thus, all such variations and equivalent modifications are also embraced within the scope of the invention as defined in the appended claims.

A composite machine for drying dishes and cleaning vegetables and fruits includes a dish-drying body, an ozone generator, a cover and a switching element. The cover selectively covers the dishes or allows the vegetables and fruits to be received therein. The switching element is switchable to be electrically connected to the dish-drying body or the ozone generator. The dish-drying body generates hot air to dry the dishes when the switching element is electrically connected to the dish-drying body. The ozone generator generates ozone to clean the vegetables and fruits when the switching element is electrically connected to the ozone generator. With this arrangement, the operation of drying dishes or cleaning vegetables and fruits can be executed as demands. Thus, the utility rate of the machine is increased and the space can be used more effectively. As a result, the cost is reduced and the maintenance is easy.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of and a system for exposing a pattern on an object, such as a semiconductor wafer or a mask coated with resist, by a charged particle beam passing through a blanking aperture array to make multibeam. 2. Description of the Related Art In the current trend for miniaturization of the elements used in semiconductor integrated circuits, application of charged particle beam exposure systems in mass production is eagerly awaited. Generally, electrons are used for charged particles. In such a system, it is possible to perform fine processing at 0.05 μm or smaller with a positioning precision of 0.02 μm or smaller. A charged particle beam is caused to scan and, as a result, the exposure time is longer compared to that in light exposure. To reduce this problem, there is a method that uses a blanking aperture array (BAA) to make a charged particle beam a multibeam (U.S. Pat. No. 4,153,843 corresponding to First Publication No. 53-117387 of Japanese Patent Application). With this method, exposure of minute patterns at high speed, for example 100 mm/sec, of a mobile stage upon which the wafer is mounted is expected. The mobile stage is continuously moved while the multibeam is deflected by a main deflector and a sub deflector. However, since exposure is performed by the charged particle beam scanning, the exposure takes longer than in photo exposure. Because of this, it is necessary to improve the throughput of the charged particle beam exposure system. (1) Reduction in Throughput of Exposure Depending Upon the Scanning Method Scanning of the charged particle beam on a semiconductor wafer is performed by the mobile stage upon which the wafer is mounted, the main deflector and the sub deflector that are positioned above the mobile stage. Normally, the main deflector is the electromagnetic type and the sub deflector is the electrostatic type. The ranges over which scanning is possible at the required accuracy with these means are, from largest to smallest: the mobile stage, the main deflector, the sub deflector. However, the order of their scanning speeds is, from fastest to slowest: the sub deflector, the main deflector, the mobile stage. By taking advantage of these characteristics of the scanning means, the scanning of the charged particle beam onto the wafer is performed as shown in FIGS. 13(A) and 13(B). In FIG. 13(A), areas 111 to 115 on the semiconductor wafer 10 are scanned continuously by the mobile stage, as indicated with the alternate long and short line L1. Also, the areas between the centers of the subfields are scanned in steps by the main deflector in the order of the subfields: 12, 13, 14, 15D, • • • . However, if no exposure data are present in the subfields between the subfields 13 and 16, for instance, the main deflector jumps from the subfield 13 to the subfield 16. Each subfield is scanned by the sub deflector in the state in which the main deflection is constant. In FIG. 13(B), the range over which the multibeam, which has passed through a BAA 30, to be explained later, can be deflected by the sub deflector is A1, indicated by the alternate long and short line, with the scanning point of the main deflector at Q1. The subfield 12 is scanned by the sub deflector along the alternate long and two short dashes line L3 and the dotted line L4 in the order of cell strips 121 to 125. The alternate long and two short dashes line L3 is a scanning line during exposure and the dotted line L4 is at blanking (flyback). During sub scanning, since the semiconductor wafer 10 is continuously moving on the mobile stage, the scanning point of the main deflector is at Q2 at the end of the scanning of the subfield 12. In this state, the scanning point of the main deflector is changed in one step to Q3, shifting the range of the sub deflection to A2, indicated with the alternate long and two short dashes line, and the subfield 13 is scanned by the sub deflector in the order of cell stripes 131 to 135 in the same manner. The scanning described above is performed repeatedly. When exposure data are present in the cell stripe 131 but no exposure data are present in the cell stripes 132 to 135, for instance, too, the main scanning point must be changed from Q2 to Q3 in a large step and because of this, settling time at the time of the step change is lengthened, causing a reduction in the throughput of exposure. In addition, if cell stripes are shortened to perform sub scanning so as to ensure that the scan never exceeds the sub scanning range A1, the total number of cell stripes must be increased, increasing the number of times flyback must be implemented during sub scanning and lowering the throughput of exposure. (2) Lowering Throughput of Exposure During Sub Scanning FIG. 14(A) shows a drive circuit for an electrostatic sub deflector 20 for deflecting a multibeam EB2. The quantity of sub deflection QRX2 is converted to an analog current QRX3 at a D/A converter 21 and changes as shown in FIG. 14(B). The current QRX3 is converted to a voltage QRX4 by a current/voltage converter 22. Although the response frequency of the D/A converter 21 is approximately 10 to 20 MHz, the frequency of the data supplied to the BAA is set to, for instance, 400 MHz for high speed exposure and, therefore, it is necessary to cause the sub deflector 20 to continuously scan the multibeam EB2 by smoothing the waveform of the voltage QRX4. To achieve this, the voltage QRX4 is amplified and the high frequency component is cut at an amplification & low pass filter circuit 28 and becomes a smooth voltage QRX5, as shown in FIG. 14(B). Points R1, R2 and R3 in the graph of the voltage QRX5 correspond to points R1, R2 and R3 respectively in FIG. 13(B). During the time t3, the current QRX3 changes in small steps from the maximum value to the minimum value, and the voltage QRX5 changes linearly from the minimum value to the maximum value. However, when the current QRX3 has changed in a large step from the minimum value to the maximum value, the voltage QRX5, with its high frequency component cut at the amplification & low pass filter circuit 23, steps down gently and the time period elapsing during this process, i.e., the time t2, is approximately equal to t3. The time t1 or t3 and the time t2 are both approximately 4 μs. Since t2 is wasted time, in order to improve the throughput of exposure, it is necessary to minimize t2/t1. (3) Lowering Throughput of Exposure Caused by Error Detection and Correction FIG. 15 shows a BAA 30 and a multi-beam controlling circuit. In the BAA 30, a lattice of apertures 33 is formed inside an area 32 of a thin substrate 31. For each aperture 33, a pair of electrodes, one a common electrode 34 and the other a blanking electrode 35, are formed on the substrate 31 with the common electrode 34 connected to the ground line. A charged particle beam is projected to the area 32 on the substrate 31. A charged particle beam that has passed through an aperture 33 then passes through a round aperture on the aperture stop under the BAA 30 so long as the potential of the blanking electrode 35 is set to 0 V. However, if a non-zero potential Vs is applied to the blanking electrode 35, the charged particle beam is deflected and is blocked at the aperture stop under the BAA 30. Consequently, by providing a 0/Vs potential pattern to the blanking electrodes 35 in correspondence to the bitmap data of a exposure pattern, a desired fine pattern can be exposed on the semiconductor wafer 10. For instance, each aperture 33 is a square with its sides at 25 μm and the area exposed on the semiconductor wafer 10 by this aperture 33 is an approximately square shape with sides at 0.08 μm. The direction X is referred to as the lengthwise direction of the rows of the apertures 33 and two actual rows of the apertures 33 are considered as one logical row. For the sake of simplification, FIG. 15 shows the apertures 33 in three logical rows over twenty columns, but in reality, the apertures 33 may be formed, for instance, in eight logical rows over 128 columns. When there are m logical rows over n columns of apertures 33, the aperture 33 and the blanking electrode 35 in the i-th row at the j-th column are indicated as the aperture 33(i,j) and the blanking electrode 35(i,j) respectively. The pitch p of the apertures 33 in the direction Y must be, for instance, three times the length a of one side of the aperture 33, in order to secure enough area for the electrodes and wiring. A BAA drive circuit (multibeam control circuit) 40 is provided with dot buffer memories 411 to 41n in which bitmap data of patterns provided through read/write circuit 42 are written. A dot buffer memory 41j (j is anyone of 1 to n) outputs dot data for j-th column of the blanking electrode 35. Each of the dot buffer memories 411 to 41n have the same storage capacity. A n-bit parallel data that corresponds to the 1st to nth column of the blanking electrodes 35 is output by a clock, address and control signals from a control circuit 43 which is operated in synchronization with a clock φ0. Each of the dot buffer memories 411 to 41n is divided into, for instance, two areas so that while dot data are written in one area through a direct memory access, dot data are read out from the other area. Each time the read and write for one frame is completed, the read area and the write area are switched. A dot data from the dot buffer memory 41j having parallel/serial conversion circuit at an output stage is provided to the data input of the least significant bit of a shift register 44j. The shift register 44j is shifted by one bit toward the higher digit by one clock pulse from the control circuit 43, a frequency of the clock being, for instance, 400 MHz. As shown in FIG. 16, the electrode 35(i, j) is connected via a transistor switch to a voltage source line of the potential Vs or a grand line. A k-th bit output from the least significant bit (0-th bit) of the shift registers 44j is connected to a control input of the transistor switch. Where k is expressed as k=2 (p/a) (i-1) when j is an odd number and k=2 (p/a) (2i-1) when j is an even number. The potential of the blanking electrode 35(i, j) is at 0/Vs when the k-th bit of the shift registers 44j is `1`/`0`, and the charged particle beam which has passed through the aperture 33(i, j) is radiated on the semiconductor wafer 10 only when this potential is at 0 V. The scanning speed of the charged particle beam is adjusted at a constant level so that, when the cycle of the clock φ is T, supposing that the charged particle beam passes the aperture 33(1, j) at a time point t=0 irradiates a point P on the semiconductor wafer 10, the charged particle beams that pass through the aperture 33(2, j), the aperture 33(3, j), • • • , the aperture 33(m, j) at time points t=2(p/a)T, t=4(p/a)T, • • • , T=2(m-1) (p/a)T respectively, irradiate the same point P on the semiconductor wafer 10. Thus, on the semiconductor wafer 10, the same spot is exposed m times with the same dot data. In addition, the spaces between dots that are exposed at the time point t after the beam passes through the aperture 33(i, j), j=1, 3, 5, • • • , n-1 are exposed at time point t+(p/a)T after the beam passes through the apertures 33(i, j), j=2, 4, 6, • • • , n. For instance, when the area exposed on the semiconductor wafer 10 by one aperture in BAA is a square with sides at 0.08 μm and the area to be exposed on a semiconductor chip is a square with sides at 20 mm, at least (20,000/0.08) 2 =62.5 Gbit is needed for exposure data. For instance, four times as many as that, namely 250 Gbit, is needed for exposure data if length adjustment of patterns or correction of proximity effect with high accuracy is performed. Since huge quantities of data are read out, written and transferred at high speed via the BAA drive circuit 40 in FIG. 15 and a data generating circuit provided at a stage preceding the BAA drive circuit, it is necessary to improve reliability by detecting an error when bits are inverted due to noise. Usually, parity check is employed to detect data errors in the transfer path. However, since one parity bit is required for each byte of 8 bits, 64 parity check circuits will be required for 512-bit parallel data, increasing the scale of the circuits. In addition, although error detection and correction can be performed by an ECS (Error Correction System), the circuit scale will be larger than that of the party check circuits and, moreover, high speed processing at the 400 MHz level becomes difficult. Thus, the speed at which data are transferred to the BAA 30 must be lowered for error detection, causing a reduction in throughput of exposure. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method of and a system for exposing a pattern on an object by a charged particle beam using a blanking aperture array that can improve the throughput of exposure. According to the 1st aspect of the present invention, there is provided a method of exposing a pattern on an object by a charged particle beam, the method using: a blanking aperture array mask having a substrate, aperture array on the substrate and a pair of electrodes on the substrate for each aperture, the blanking aperture array being positioned in a path of the charged particle beam; a charged particle beam radiating apparatus for making a multibeam by projecting the charged particle beam on to the blanking aperture array mask; a multibeam controller for providing or not a voltage between each of the pairs of electrodes based upon pattern bitmap data in order to radiate or not the charged particle beam passed through the apertures on the object; and a deflector for deflecting the multibeam; the method comprising the steps of: (1) counting a total bit number of one of "1" and "0" in the bitmap data within a band area as a first checksum before the bitmap data are supplied to the multibeam controller, the band area being for continuously scanning the charged particle multibeam on the object; (2) obtaining a second checksum of the bitmap data within the band area before the bitmap data are supplied to the multibeam controller, the second checksum corresponding to the first checksum; and (3) comparing the first checksum against the second checksum. With the 1st aspect of the present invention, the checksum is detected in unit of bitmap data within the range of the band areas for scanning, the structure for detecting errors is simplified and it becomes unnecessary to lower the speed at which the band areas is scanned on account of error detection, making it possible to improve the throughput of exposure. In the 1st mode of the 1st aspect of the present invention, the step (2) is executed in real time during exposure, the bitmap data for the second checksum sequentially taken out from an output of the multibeam controller. In the 2nd mode of the 1st aspect of the present invention, the step (1) is performed by calculating a total area of a figure within the band area before expanding the figure data into the bitmap data. With the 2nd mode, by determining the entire area of the figures within the range of the band areas for scanning before the figure data are expanded into bitmap, a first checksum can be determined with ease. In the 3rd mode of the 1st aspect of the present invention, the step (1) is executed after expanding the figure data into the bitmap data. In the 4th mode of the 1st aspect of the present invention, the step (1) is performed by calculating a total area of a figure within the band area before expanding the figure data into the bitmap data; and the step (2) is executed after expanding the figure data into the bitmap data; the method further comprises the step of executing the step (2) again when the first and second checksum are not equal to each other. With the 4th mode, since error detection and correction are performed during bitmap expansion processing, the reliability of exposure data improves. Also, since it is not necessary to provide two same systems of bitmap expansion, the structure for error detection and correction during bitmap expansion processing can be simplified. In the 5th mode of the 1st aspect of the present invention, the step (1) and (2) are performed in parallel for two sets of identical bitmap data; the method further comprises the step of executing the step (2) again when the first and second checksum are not equal to each other. With the 5th mode, since error detection and correction are performed during bitmap expansion processing, the reliability of the exposure data improves. In the 6th mode of the 1st aspect of the present invention, the step (1) includes the steps of: taking out the bitmap data sequentially in an unit of n bits from an output of the multibeam controller; counting a total bit number of one of "1" and "0" in the n bits; accumulating the total bit number as a sum; holding the sum of (m+1) number spanning from the m times previous sum to the current sum; subtracting the current sum from the m times previous sum to obtain a refocus value for correcting focal point blur of the multibeam caused by Coulomb repelling force; and obtaining the sum as the first checksum corresponding to the band area. With the 6th mode, since the calculation of a checksum can be performed with interim results of the calculation of the refocus value, the structure for determining the checksum is simplified. According to the 2nd aspect of the present invention, there is provided a method of exposing a pattern on an object by a charged particle beam, the method using: a blanking aperture array mask having a substrate, aperture array on the substrate and a pair of electrodes on the substrate for each aperture, the blanking aperture array being positioned in a path of the charged particle beam; a charged particle beam radiating apparatus for making a multibeam by projecting the charged particle beam on to the blanking aperture array mask; a multibeam controller for providing or not a voltage between each of the pairs of electrodes based upon pattern bitmap data in order to radiate or not the charged particle beam passed through the apertures on the object; a mobile stage for mounting the object; a sub deflector for deflecting the multibeam within a sub deflection range; and a main deflector for deflecting the multibeam within a main deflection range, the main deflection range being larger than the sub deflection range; the method comprising the steps of: dividing exposure area into main rectangular areas and dividing each of the main rectangular areas into sub rectangular areas, the sub rectangular areas in the same main rectangular area being identical bands and being parallel to one another; scanning linearly once as a sub scanning by the sub deflector along the sub rectangular area to expose the sub rectangular area, with moving the mobile stage in a length direction of the sub rectangular area at a constant speed V and with making a deflection by the main deflector constant; determining a value k that satisfies kVΔt≦AL<(k+1)VΔt, where AL is a distance along a direction of a movement of the mobile stage between a boundary of the sub rectangular area and a boundary of a range to be able to scan by the sub deflector at a first start time point of the sub scanning, and Δt is a time spanning from a start point of the sub scanning to a next start point of the sub scanning, exposing k number of the sub rectangular areas lying continuously in parallel to each other as a first exposing area by repeating the sub scanning k number of times, if k is smaller than p which is a number of the sub rectangular area in one of the main rectangular areas; and jumping a deflection by the main deflector toward an approximate center of remaining sub rectangular areas whose number is (p-k) inside the main rectangular areas after the first exposing area; exposing remained (p-k) number of the sub rectangular areas as a second exposing area by repeating the sub scanning (p-k) times after the jumping is settled. With the 2nd aspect of the present invention, when p>k, the step change of deflection by the main deflector is smaller compared to that when p≦k. Therefore, the wasted settling time for the step change is reduced, improving the throughput of exposure. Furthermore, since the sub rectangular areas do not have to be shortened to ensure that the scan never exceeds the sub deflection range, and consequently, an increase in the total number of sub rectangular areas can be avoided, a reduction in the throughput caused by an increase in the total of wasted time elapsing between scanning of a sub rectangular area and scanning of the next sub rectangular area is prevented. In the 1st mode of the 2nd aspect of the present invention, a jump flag is provided in regard to each of the sub rectangular areas and a value of the jump flag, corresponding to k-th the sub rectangular area from one end in the main rectangular area, is made to differ from a value of other jump flags, and the jumping is performed based upon the jump flag. With the 1st mode, because the value of the jump flag is determined at the time of exposure data generation, it is not necessary to calculate k in real time during the exposure processing. In the 2nd mode of the 2nd aspect of the present invention, the k is calculated before scanning of next the main rectangular areas starts; and the jumping is performed based upon a number of the sub scanning, the number of the sub scanning being counted after starting a scan of the main rectangular area. With the second mode, since it is not necessary to use a jump flag, the quantity of exposure data can be reduced and the structure of the exposure data can be simplified. In the 3rd mode of the 2nd aspect of the present invention, k-th the sub rectangular area currently being scanned is judged by a elapsed time from starting a scan of the main rectangular areas having reached (AL/V-t); and the jumping is performed based upon the judgment. With the 3rd mode, it is not necessary to count the scanning number of the sub rectangular area. According to the 3rd aspect of the present invention, there is provided a method of exposing a pattern on an object by a charged particle beam, the method using: a blanking aperture array mask having a substrate, aperture array on the substrate and a pair of electrodes on the substrate for each aperture, the blanking aperture array being positioned in a path of the charged particle beam; a charged particle beam radiating apparatus for making a multibeam by projecting the charged particle beam on to the blanking aperture array mask; a multibeam controller for providing or not a voltage between each of the pairs of electrodes based upon pattern bitmap data in order to radiate or not the charged particle beam passed through the apertures on the object; a deflector for deflecting the multibeam; a digital-to-analog converter; and an amplification & low pass filter circuit having a control input to select one of a first cut-off frequency and a second cut-off frequency without changing an amplification factor, the second cut-off frequency being larger than the first cut-off frequency, the amplification & low pass filter circuit being connected between the digital-to-analog converter and the deflector; the method comprising the steps of: changing an output of the D/A converter from a third value toward a fourth value a plurality of times so as to change an input drive signal of the deflector smoothly, and making the amplification & low pass filter circuit select the first cut-off frequency during the changing; and changing the output of the D/A converter from the fourth value to the third value in one time while the charged particle multibeam is not irradiated on the object, and making the amplification & low pass filter circuit select the second cut-off frequency while the charged particle multibeam is not irradiated on the object. In the 3rd aspect of the present invention, since the (duration of the second process)/(duration of the first process) can be reduced compared to that when the cut-off frequency is fixed at a first value, the wasted time is reduced and the throughput of exposure is improved. According to the 4th aspect of the present invention, there is provided a system for exposing a pattern on an object by a charged particle beam, the system comprising: a blanking aperture array mask having a substrate, aperture array on the substrate and a pair of electrodes on the substrate for each aperture, the blanking aperture array being positioned in a path of the charged particle beam; a charged particle beam radiating apparatus for making a multibeam by projecting the charged particle beam on to the blanking aperture array mask; a multibeam controller for providing or not a voltage between each of the pairs of electrodes based upon pattern bitmap data in order to radiate or not the charged particle beam passed through the apertures on the object; and a deflector for deflecting the multibeam; the system further comprising: a first checksum calculator for counting a total bit number of one of "1" and "0" in the bitmap data within a band area as a first checksum before the bitmap data are supplied to the multibeam controller, the band area being for continuously scanning the charged particle multibeam on the object; a second checksum calculator for obtaining a second checksum of the bitmap data within the band area before the bitmap data are supplied to the multibeam controller, the second checksum corresponding to the first checksum; and a comparator for comparing the first checksum against the second checksum. According to the 5th aspect of the present invention, there is provided a system for exposing a pattern on an object by a charged particle beam, comprising: a blanking aperture array mask having a substrate, aperture array on the substrate and a pair of electrodes on the substrate for each aperture, the blanking aperture array being positioned in a path of the charged particle beam; a charged particle beam radiating apparatus for making a multibeam by projecting the charged particle beam on to the blanking aperture array mask; a multibeam controller for providing or not a voltage between each of the pairs of electrodes based upon pattern bitmap data in order to radiate or not the charged particle beam passed through the apertures on the object; a mobile stage for mounting the object; a sub deflector for deflecting the multibeam within a sub deflection range; and a main deflector for deflecting the multibeam within a main deflection range, the main deflection range being larger than the sub deflection range; the system further comprising: means for dividing exposure area into main rectangular areas and for dividing each of the main rectangular areas into sub rectangular areas, the sub rectangular areas in the same main rectangular area being identical bands and being parallel to one another; means for determining a value k that satisfies kVΔt≦AL<(k+1)VΔt, where AL is a distance along a direction of a movement of the mobile stage between a boundary of the sub rectangular area and a boundary of a range to be able to scan by the sub deflector at a first start time point of a sub scanning, and Δt is a time spanning from a start point of the sub scanning to a next start point of the sub scanning; and exposure controller for scanning linearly once as the sub scanning by the sub deflector along the sub rectangular area to expose the sub rectangular area, with moving the mobile stage in a length direction of the sub rectangular area at a constant speed V and with making a deflection by the main deflector constant, for exposing k number of the sub rectangular areas lying continuously in parallel to each other as a first exposing area by repeating the sub scanning k number of times, if k is smaller than p which is a number of the sub rectangular area in one of the main rectangular areas, for jumping a deflection by the main deflector toward an approximate center of remaining sub rectangular areas whose number is (p-k) inside the main rectangular areas after the first exposing area, and for exposing remained (p-k) number of the sub rectangular areas as a second exposing area by repeating the sub scanning (p-k) times after the jumping is settled. According to the 6th aspect of the present invention, there is provided a system for exposing a pattern on an object by a charged particle beam, comprising: a blanking aperture array mask having a substrate, aperture array on the substrate and a pair of electrodes on the substrate for each aperture, the blanking aperture array being positioned in a path of the charged particle beam; a charged particle beam radiating apparatus for making a multibeam by projecting the charged particle beam on to the blanking aperture array mask; a multibeam controller for providing or not a voltage between each of the pairs of electrodes based upon pattern bitmap data in order to radiate or not the charged particle beam passed through the apertures on the object; a deflector for deflecting the multibeam; and a deflection controller; the deflection controller comprising: a digital-to-analog converter; an amplifier & low pass filter having a control input to select one of a first cut-off frequency and a second cut-off frequency without changing an amplification factor, the second cut-off frequency being larger than the first cut-off frequency, the amplification & low pass filter circuit being connected between the digital-to-analog converter and the deflector; and a waveform controller for changing an output of the D/A converter from a third value toward a fourth value a plurality of times so as to change an input drive signal of the deflector smoothly, and making the amplification & low pass filter circuit select the first cut-off frequency during the changing, and for changing the output of the D/A converter from the fourth value to the third value in one time while the charged particle multibeam is not irradiated on the object, and making the amplification & low pass filter circuit select the second cut-off frequency while the charged particle multibeam is not irradiated on the object. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of an apparatus for charged particle multibeam exposure in the first embodiment according to the present invention; FIG. 2 is a block diagram showing a structural example of a deflection quantity calculating circuit in FIG. 1; FIG. 3 is a block diagram showing a structure of a main portion of the setting circuit in FIG. 2; FIG. 4 is a block diagram showing a structural example of a data generating circuit in FIG. 1; FIG. 5 is a block diagram showing a structural example of a BAA & refocus coil drive circuit in FIG. 1; FIG. 6 is a waveform diagram showing an operation of a sub deflector drive circuit in FIG. 1; FIG. 7(A) illustrates a method of scanning a charged particle multibeam and FIG. 7(B) is a vector diagram showing a relationship of data in FIG. 2; FIG. 8(A) illustrates figure data inside a cell stripe and FIG. 8(B) illustrates a basic figure; FIG. 9 illustrates hierarchical exposure data; FIG. 10 is a block diagram showing a jump judgment circuit in the second embodiment according to the present invention; FIG. 11 is a block diagram showing a data generating circuit in the third embodiment according to the present invention; FIG. 12 shows a sub deflector drive circuit in the fourth embodiment according to the present invention; FIGS. 13(A) and 13(B) illustrate a method of charged particle multibeam exposure in the prior art which uses a BAA; FIG. 14(A) shows a sub deflector drive circuit in the prior art and FIG. 14(B) is a waveform diagram showing an operation of this circuit; FIG. 15 shows a BAA and multibeam control circuit in the prior art; and FIG. 16 shows a portion of the circuit in FIG. 15. DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment FIG. 1 shows a schematic structure of a system for charged particle multibeam exposure in the first embodiment according to the present invention. (1) Overview of System for Charged Particle Multibeam Exposure A charged particle beam EB0 emitted from a charged particle beam emitting apparatus 50 is made to multibeam through a BAA 30, and a portion EB1 of the charged particle beam is deflected and is blocked at the aperture stop 51 under the BAA 30. Consequently, the cross section of the charged particle beam EB1 (ON beams) is formed to be a dot pattern. The charged particle beam EB0 is emitted continuously and between the cell stripe scanning end point R2 and the cell stripe scanning start point R3 in FIG. 40, for instance, the entire multibeam is deflected by a blanking deflector 52 and is blocked by an aperture stop 51. refocus Since the ON beams EB2 conflict with each other due to Coulomb forces acting between the beams, the focal point is offset downward relative to the surface of the semiconductor wafer 10, resulting in a blurred image. In order to prevent such blurring, a refocus coil 53 is provided under the aperture stop 51, coaxially with the optical axis and an electrical current proportionate to the number of ON beams EB2 is supplied to the refocus coil 53 so that the ON beams EB2 approach each other due to the magnetic field of the refocus coil 53. The ON beams EB2 is deflected by a sub deflector 20 and a main deflector 54, and is focused on the semiconductor wafer 10 through a electromagnetic lens not shown. The semiconductor wafer 10 is mounted on a mobile stage 55. The movement of the mobile stage 55 is controlled by a stage control circuit 56 with the position of the mobile stage 55 being detected by a laser interferometric measuring machine 57. The ON beams EB2 are radiated at the intersection, which is mobile stage scanning position P, of a optical axis of the exposure system and the semiconductor wafer 10. A laser gauge interferometer 57 provides the coordinates (PX, PY) of the mobile stage scanning position P relative to a fixed origin point on the semiconductor wafer 10, to a deflection quantity calculating circuit 58. In order to ensure that multibeam EB2 is irradiated at the target position on the semiconductor wafer 10 by the main deflector 54 and the sub deflector 20, the deflection quantity calculating circuit 58 calculates the main deflection quantity PQX2 and the sub deflection quantity QRX2, which are to be explained later, and supplies them to a D/A converter 59 and a D/A converter 21 respectively. For the purpose of simplification, the drive circuits for only one deflection coil of the main deflector 54 and for only one deflection electrode plate of the sub deflector 20 are shown in FIG. 1. So, the drive circuits for the Y-direction deflection components in the main deflector 54 and in the sub deflector 20 are omitted in the figure. The main deflection quantity PQX2 is converted to an analog current PQX3 by the D/A converter 59 and then amplified by an amplifier 60. It is then supplied to the main deflector 54 as a drive current PQX4. Bitmap data for exposure and refocus data are generated by a data generating circuit 61, and are supplied to the BAA 30 and the refocus coil 53 respectively via a BAA & refocus coil drive circuit 62. (2) Sub Deflector Drive Circuit The sub deflection quantity QRX2 is converted to an analog current QRX3 at the D/A converter 21, further converted to a voltage QRX4 at a current/voltage converter 22 and is then amplified with its high frequency component, which has been generated by the step change, cut at an amplification & low pass filter circuit 23A to become a drive voltage QRX5 before it is supplied to the sub deflector 20. In the amplification & low pass filter circuit 23A, one end each of a resistor 232 with a resistance R1, a resistor 233 with a resistance R2, and a switch element SW1 is connected to the inverting input of a operation amplification circuit 231 with the other end of the resistor 233 connected to the output of the operation amplification circuit 231. The other end of the switch element SW1 is connected to an output of the operation amplification circuit 231 via a capacitor 234 and a switch element SW2. The switch elements SW1 and SW2 interlock with each other by a control signal S2 from the deflection quantity calculating circuit 58 to be ON/OFF controlled as shown in FIG. 6. Namely, while the current QRX3 changes in small steps, the switch elements SW1 and SW2 are turned ON so that the amplification & low pass filter circuit 23A performs the amplification operation and the high frequency component cutting operation, to smooth the step change to the voltage QRX4. At this time, the cutoff angular frequency of the amplification & low pass filter circuit 23A is at 1/(R2·C) and the amplification factor of the amplification & low pass filter circuit 23A is at R2/R1. When the sub deflection quantity QRX2 changes in a large step from the maximum value to the minimum value, the control signal S2 turns the switch elements SW1 and SW2 OFF for a specific length of time. With this, the capacity connected with the resistance R2 becomes the capacity component of the resistor 233 and its lead line. As a result, the cutoff angular frequency becomes higher and the voltage QRX5 returns from the maximum value to the minimum value quickly. At this time, since the amplification factor of the amplification & low pass filter circuit 23A remains unchanged at R2/R1, the maximum and minimum value of the voltage QRX5 are the same as those when the switch elements SW1 and SW2 are ON. When R1=500Ω, R2=2 kΩ and C=800 pF, t1 and t2 in FIG. 6 are respectively 4 μs and 200 ns so that t2/t1=1/20, making it possible to reduce the exposure time to 21/40 of that in the prior art. (3) Method of Charged Particle Multibeam Scanning FIG. 7(A), which corresponds to FIG. 13(B) shows a method of charged particle multibeam scanning. Since no data are present in cell stripes 132 to 135 in FIG. 13(B), the cell stripe 131 is reassigned as cell stripe 126 to be included in the subfield 12A and the subfield 13 is omitted in FIG. 7(A). The vector OR1 of the scanning start point R1 in the subfield 12A relative to the fixed origin point O on the semiconductor wafer 10 is expressed as OR1=OP1+P1Q1+Q1R1 (1) where, OP1: a vector of scanning by the mobile stage 12 with P1 being the scanning position of the mobile stage P1Q1: a vector of the main scanning performed by the main deflector 54, with Q1 being the main scanning position Q1R1: a vector of the sub scanning performed by the sub deflector 20, with R1 being the sub scanning position. The mobile stage scanning position P1 is the intersection of the optical axis of the exposure system and the semiconductor wafer 10 and moves along L1 at a constant speed in the direction indicated with the arrow. The sum of the vector OP1 and the position vector of the mobile stage is constant. During sub scanning, although the main scanning vector P1Q1 is constant, the point Q1 conforms to the movement of the point P1. The subfield 12A is scanned by the sub deflector 20 along the solid line L3 and the dotted line L4 in the order of cell stripes 121 to 126. The solid line L3 is during the exposure and the dotted line L4 is during blanking. The range over which the multibeam EB2, which has passed through the BAA 30, can be deflected by the sub deflector is A1, indicated with the alternate long and short line, at the scanning start point R1 of the scanning of the subfield 12. The number of cell stripes k that can be scanned by the sub deflector 20 with a constant main deflection satisfy kVΔt≦AL<(k+1)VΔt (2) where AL: distance between the sub scanning start point R1 and the boundary of range A1 Δt: the sum of cell stripe scanning time from the point R1 to the point R2 and the flyback time elapsing from the point R2 to the point R3 V: stage movement speed. FIG. 7(A) shows a case when k=5 and the first to k-th cell stripes can be sub-scanned under the constant main scanning vector P1Q1 and the cell stripe A6 cannot be sub-scanned. However, since the quantity of data is huge, only one set of coordinates data concerning the main scanning position is provided in each subfield in the exposure data. FIG. 9 shows the hierarchical exposure data. The subfield data for each subfield are comprised of the start address of the cell stripe data, the number of cell stripes p, the X coordinate QX10 of the main scanning position and the Y coordinate QY10 of the main scanning position. The cell stripe data for each stripe are comprised of a start address of the bitmap data in a cell stripe, the number of words of the bitmap data in the cell stripe, the checksum of the bitmap data in the cell stripe, a jump flag JF indicating whether the current stripe is the k-th cell stripe (`1`) or not (`0`) and the X coordinate QRX0 of the sub scanning position relative to the main scanning position (QX10, QY10). The checksum represents the total bit number of "1" in the bitmap data of a cell stripe. In the bitmap data shown in FIG. 9, a hatched square indicates bit "1" and it corresponds to an ON beam which passes through the BAA 30 and the aperture stop 51 in FIG. 1. The number of bits in one word (one row) of the bitmap data is equal to n as in FIG. 15. The refocus data, which are equal to the number of the ON beams passing through the BAA 30, correspond to individual words in the bitmap data of a cell stripe. The refocus data in FIG. 9 shows a case in which m in FIG. 15 is at 3 and the following calculation is performed using the number of ON beams: ______________________________________number of ON beams refocus data______________________________________ 6 6 7 6 + 7 = 1313 13 + 13 = 2612 26 + 12 - 6 = 32 4 32 + 4 - 7 = 29______________________________________ FIG. 3 shows the structure of the main portion of the setting circuit 70 in FIG. 2. In a buffer memory 701, the subfield data and the cell stripe data, excluding the checksum in FIG. 9, are written in advance and every time the scanning of a subfield ends, the X coordinate QX10 and the Y coordinate QY10 of the main scanning position of the next subfield are respectively held at a register 702X and a register 702Y. Also, every time the scanning of a cell stripe starts, the jump flag JF of that cell stripe is held in a flip-flop 703. A counter 704A is cleared to 0 every time the scanning of a subfield ends and is incremented by a control signal S1 in FIG. 6 every time the scanning of a cell stripe starts. When the jump flag JF is at "1", the calculation part 705, using the number of cell stripes p in the subfield, the count k on the counter 704A and the width w of a cell stripe set in a register 704B, calculates the main scanning position X coordinate QX11 as QX11=QX10+(2p-k)w/2 (3) and the QX11 is held in a register 702A. A selector 706 selects the output QX10 from the register 702X as QX1 when the jump flag JF is at "0" and selects the output QX11 from the register 702A as QX1 when the jump flag JF is at "1". As explained later, QX1 is used as the X coordinate of the next main scanning position. As for the Y coordinate of the main scanning position, since there is no change even when the jump flag JF is at "1", QY10 held in the buffer register 702Y can be used as QY1. Through such processing, when the scanning of the cell stripe 125 ends in FIG. 7(A), for instance, the main scanning position jumps from Q2 to Q4. Since it is necessary to subtract (2p-k)w/2 in the formula (3) above to obtain the X coordinate of the subfield 126 relative to the main scanning position after the jump, correction is made in the following manner: Every time the scanning of a cell stripe ends, the X coordinate QRX0 of the sub scanning position of the next cell stripe relative to the main scanning position is held in a register 707X. Normally 0 is held in a register 707A, but when QX11 is held in the register 702A, the register 707A holds (2p-k)w/2 and is cleared to 0 when the scanning of the subfield ends. The difference between the output of the register 707X and the output of the register 707A is calculated in a subtractor 708 as the corrected sub scanning position QRX. A control circuit 709 generates and outputs various types of control signals for component elements inside and outside the setting circuit 70. In the method of scanning described above, since the change in the main scanning vector is smaller than that when jumps are made between subfields, the wasted settling time during the step change is reduced and an improvement in the throughput of exposure is achieved. Moreover, since the cell stripes do not have to be shortened in order to ensure that the sub scan never exceeds the sub scanning range A1, an increase in the total number of cell stripes can be avoided and reduction in the throughput due to an increased number of occurrences of flyback during sub scanning is prevented. (4) Deflection Quantity Calculating Circuit 58 A structural example of the deflection quantity calculating circuit 58 in FIG. 1 is shown in FIG. 2. FIG. 7(B) shows the relationship of the data in FIG. 2. FIG. 7(B) corresponds to the scanning shown in FIG. 7(A) and point P indicates an arbitrary position between the point P1 and the point P2. Normally, at the end of the scanning of each subfield, or if the jump flag JF is at "1" at the end of the cell stripe in which the jump flag is at "1", the setting circuit 70 causes a register 71X and a register 71Y to hold the X coordinate QX1 and the Y coordinate QY1 of the main scanning position Q1 respectively, at a timing of a latch pulse S3 and also causes a register 72X and a register 72Y to hold the X coordinate PX and the Y coordinate PY of the stage scanning position P as PX1 and PY1 respectively. A subtractor 73X calculates the difference PQX1 between the contents QX1 of the register 71X and the contents PX1 of the register 72X and a subtractor 73Y calculates the difference PQY1 between the contents QY1 of the register 71Y and the contents PY1 of the register 72Y. A correction circuit 74 corrects the deviation, which are in the direction of the deflection of the main deflector 54 and the ratio (magnetic field intensity)/(the input current) of the main deflector 54, from the design values for (PQX1, PQY1), and outputs the result as (PQX2, PQY2). The correction circuit 74 is a primary conversion circuit for the input coordinates and, in ideal case, functions as a unit matrix. Every time the scanning of a cell stripe ends, a counter 75Y is cleared with a clear signal CLRY from the setting circuit 70 and after the control signal S2, shown in FIG. 6, is a kept at low for a specific length of time, a clock CLKY is supplied to the counter 75Y and counted. The count NY on the counter 75Y is supplied to a scanning memory 76Y as an address input. Also, every time the scanning of a cell stripe ends, the X coordinate of the next cell stripe is held in a register 75X. The difference ΔX between PX and PX1 is calculated by a subtractor 77X and the difference ΔY between PY and PY1 is calculated by a subtractor 77Y. The difference QRX1 between QRX and ΔX is calculated by a subtractor 78X and the difference QRY1 between QRY and ΔY is calculated by a subtractor of 78Y. A correction circuit 79 corrects the deviation, which is in the direction of the deflection of the sub deflector 20 and the ratio (electric field intensity)/(input current) of the sub deflector 20, from the design values for (QRX1, QRY1) and outputs the result as (QRX2, QRY2). The correction circuit 79 is a primary conversion circuit for the input coordinates and, in ideal case, functions as a unit matrix. The main deflection quantity PQX2 and the sub deflection quantity QRX2 are supplied to the D/A converter 59 and the D/A converter 21 in FIG. 1 respectively and the main deflection quantity PQY2 and the sub deflection quantity QRY2 are supplied to drive circuits (not shown) provided for the direction Y deflection components of the deflection imparted by the main deflector 54 and the sub deflector 20 respectively. (5) BAA & Refocus Coil Drive Circuit 62 FIG. 5 shows a structural example of the BAA & refocus coil drive circuit 62 in FIG. 1. Although a BAA drive circuit (multibeam control circuit) 40 of the BAA & refocus coil drive circuit 62 is simplified in FIG. 5, it is identical to the BAA drive circuit 40 in FIG. 15. The dot data from external storage devices 71 to 77n are written in dot memories 411 to 41n of the BAA drive circuit 40 respectively. The BAA & refocus coil drive circuit 62 is provided with a checksum calculating circuit 81. In this circuit 81, the end bit in each of the shift registers 441 to 44n is supplied to a "1" totaling circuit 82, which determines the total number of bits that are set at "1" and provides the value to one of the inputs of an adder 83. The output of the adder 83 is held in a register 84 in the same cycle as the outputs from the shift registers 441 to 44n, and that value is supplied to another input of the adder 83. Thus, the accumulated value of the outputs of the "1" totaling circuit 82 is held in the register 84. Each time the accumulated value corresponding to one cell stripe is held at the register 84, this value is also held in a register 85 as a checksum. In the meantime, checksum data read into a buffer memory 87 from an external storage device 86 are sequentially held in a register 88, in correspondence to the output from the register 85. Then the output from the register 88 and the output from the register 85 are compared to each other at a comparator 89 and if it is detected that they do not match, an alarm unit 90 operates and an error address and a time point at which the error occurred are recorded in a recording device 91. Since the checksum calculating circuit 81 comprises one "1" totaling circuit 82, one adder 83 and two registers 84 and 85 for n bits, e.g., 512 bits, its structure is simpler than that required for a parity check circuit and an ECS circuit, which will require a great number of such circuits and, at the same time, error checking can be performed at a higher speed than in a complex ECS circuit. Consequently, since it is not necessary to lower the speed of data transfer to the BAA 30, an advantage is achieved in that a reduction in throughput of exposure is prevented. In the refocus coil drive circuit part, refocus data are written from an external storage device 92 into a buffer memory 93, the refocus data are sequentially read out from the buffer memory 93 in correspondence to the input of a driver 45 to be held at a register 94, and a drive current which is in proportion to that value is supplied to the refocus coil 53 by a driver 95. (6) Data Generating Circuit 61 FIG. 4 shows a structural example of the data generating circuit 61 shown in FIG. 1. The design data are converted into a format for an exposure system and then are converted to figure data. The figure data are stored in an external storage device 101 via a buffer memory 100. These figure data are partitioned into cell stripes and, as shown in FIG. 8(A), the inside of a cell stripe is divided, for instance, into patterns A1B1C1D1E1F1G1, A2B2C2D2E2F2G2 and A3B3C3D3, and they are further parsed into specific basic figures such as rectangles or triangles. For instance, the pattern A1B1C1D1E1F1G1 is divided into a rectangle A1B1C1G1 and a rectangle C1D1E1F1. In FIG. 8(B), the figure data of the rectangle ABCD is expressed with the code FC which means a rectangle, the coordinates (XB, YB) of the point B and width W and the height H of the rectangle. Consequently, the checksum can be easily obtained by calculating the total area of the figure inside the cell stripe before the figure data are expanded (converted) into a bitmap. In FIG. 4, the figure data stored in the external storage device 101 are supplied to a bitmap expansion circuit 103 via a buffer memory 102 in units of cell stripes and the bitmap expansion circuit 103 expands them into bitmap on the canvas memory 104 for one cell stripe. The bitmap data of a cell stripe in the canvas memory 104 are read out sequentially from the top portion of the cell stripe in units of n bits, which correspond to the width of the cell stripe. The bitmap data that have been read out in this manner are stored in external storage devices 801 to 80n on the one hand, and are supplied to a "1" totaling circuit 82A of the checksum calculating circuit 81A on the other hand. The checksum calculating circuit 81A is structured identically to the checksum calculating circuit 81 shown in FIG. 5, with its component elements 82A to 85A corresponding to the component elements 82 to 85 respectively. The output from the register 84A is supplied to a word shift register group 105 and is shifted in units of registers in the column direction. The number of registers in the word shift register group 105 is equal to the number of logical lines m in the BAA 30 in FIG. 15. The difference between the value held at the register 84A and the value output from the head portion of the word shift register group 105 is calculated by a subtractor 106. This difference is equal to the number of ON beams passing through the BAA 30 and the aperture stop 51 in FIG. 1 and is stored in the external storage device 92 as refocus data. The checksum calculating circuit 81A and the refocus calculating circuit having elements 82A, 83A, 84A, 105 and 106 are provided with an "1" totaling circuit 82A, an adder 83A and a register 84A for common use, and its structure is simpler compared to that of a parity check circuit or a ECS circuit. In FIG. 4, a checksum calculating part 107 obtains a checksum by calculating the total area of the figure inside the cell stripe for the figure data held in the buffer memory 100, and then the checksum is stored in the external storage device 86. The stored checksum data are held in a register 108 sequentially in correspondence to holding in the register 85A. A comparator 109 compares the contents of the register 108 against the contents of the register 85A and provides the results of the comparison to the bitmap expansion circuit 103. When the output from the comparator 109 indicates a non-match, i.e., when a data error has occurred in the buffer memory 102, the bitmap expansion circuit 103, the canvas memory 104, or the like, the bitmap expansion circuit 103 performs the bitmap expansion processing again for the cell stripe. With this, the data stored in the external storage devices 801 to 80n, 86 and 92 are overwritten for that cell stripe, improving the reliability of the exposure data. While the BAA & refocus coil drive circuit 62 in FIG. 5 performs real time processing, the data generating circuit 61 in FIG. 4 performs batch processing asynchronously with the BAA & refocus coil drive circuit 62 and, as a result, error correction through reprocessing in this manner becomes possible. A control circuit 140 performs control of the component elements shown in FIG. 4 so that the operations described above can be executed. Note that subfield data and the cell stripe data except for the checksum, in FIG. 9, are generated at a stage preceding the buffer memory 100. Second Embodiment In the first embodiment described above, the formula (2) is calculated to generate a jump flag JF while the figure data are not yet expanded in bitmap data. It is desirable to determine the value k in the formula (2) in real time during exposure, since the jump flag storage apparatus will then be unnecessary. FIG. 10(A) shows a jump judgment circuit 220 in the second embodiment according to the present invention. V, Δt and AL in the formula (2) above, are set at registers 151, 152 and 153 respectively. A multiplier 154 calculates V·Δt and a divider 155 calculates AL/(V·Δt). The integer portion k of the output value of the divider 155 is then loaded to a down-counter 156. This loading is performed during the settling time of the main deflector drive circuit preceding the start of subfield scanning. When the scanning of a subfield starts, a control signal S1, shown in FIG. 6, is provided to the clock input of the down-counter 156, and the count on the down-counter 156 is decremented every time the scanning of a cell stripe starts. When this count becomes 0, a jump preparatory signal output from a zero detection circuit 157 is set to high and processing that is identical to that performed when the jump flag JF is at "1" is performed in the setting circuit 70 in FIG. 2. Instead of calculating k in the formula (2), the circuit may be structured to make a decision that the cell stripe for which sub scanning is currently in progress is the k-th cell stripe, i.e., to output a jump preparatory signal when time T T=AL/V-t (3) has elapsed after the start of cell stripe scanning. Third Embodiment In FIG. 4, although the checksum is calculated while the figure data are not yet expanded in bitmap data, it is also possible to detect an error by providing two sets of circuits, each set comprising the buffer memory 102, the bitmap expansion circuit 103, the canvas memory 104 and the checksum calculating circuit 81A and by comparing their checksums to each other. FIG. 11 shows a data generating circuit structured to achieve this, as the third embodiment. In FIG. 11, a buffer memory 102A, a bitmap expansion circuit 103A, a canvas memory 104A, a checksum calculating circuit 81B and a register 85B are structured identically to the buffer memory 102, the bitmap expansion circuit 103, the canvas memory 104, the checksum calculating circuit 81A and the register 85A respectively. A control circuit 140A, implements the control required for the component elements shown in FIG. 11. Every time the entire data corresponding to one cell stripe are output from the canvas memories 104 and 104A, the contents in the register 85A are stored as a checksum in the external storage device 86 and if the output from the comparator 109 indicates a non-match, the bitmap expansion for that cell stripe is performed again, to rewrite the corresponding values stored in the external storage devices 86 and 92. When the third embodiment is compared against the circuit shown in FIG. 4, it is obvious that the structure of the circuit in FIG. 4 is simpler. This advantage is derived from the fact that the checksum is more easily obtained, when the figure data are not yet expanded in bitmap data, by calculating the checksum in units of cell stripes. Fourth Embodiment FIG. 12 shows a sub deflector drive circuit in the fourth embodiment according to the present invention. In this circuit, an amplification & low pass filter circuit 28B is employed in place of the amplification & low pass filter circuit 23A shown in FIG. 1. When the exposure is in progress with the control signal S2 at high, switching elements SW3 and SW4 are turned ON, switching elements SW5 and SW6 are turned OFF, switching elements SW7 and SW8 are turned ON and switching element SW9 and SW10 are turned OFF. During a flyback, with the control signal S2 at low, the switching elements SW3 and SW4 are turned OFF, the switching elements SW5 and SW6 are turned ON, the switching elements SW7 and SW8 are turned OFF and the switching element SW9 and SW10 are turned ON. When the resistance value of resistors 232A, 232B, 233A and 233B are designated R1A, R1B, R2A and R2B respectively, the amplification factor R2A/R1A during exposure is made to be equal to the amplification factor R2B/R1B during flyback. In addition, since R2A<R2B, the cutoff frequency during flyback is lower than that during exposure and t2/t1 in FIG. 6 can be reduced, compared to that in the prior art. Although preferred embodiments of the present invention has been described, it is to be understood that the invention is not limited thereto and that various changes and modifications may be made without departing from the spirit and scope of the invention. For instance, the amplification & low pass filter circuit 23 which is structured to perform inversion amplification in FIG. 1, may be structured to perform non-inversion amplification. In addition, the operation amplification circuit 231 may have a differential structure in which a pair of signals with reverse polarities from each other are output for a pair of deflection electrode plates that face opposite each other. These points apply to the amplification & low pass filter circuit 23B shown in FIG. 12, as well. Moreover, instead of the mobile stage scanning position P (PX, PY) in FIG. 1, pulses, the number of which is in proportion to the mobile stage detection position itself or in proportion to the movement distance may be used.

Before figure data are expanded into a bitmap, a checksum is calculated in unit of bitmap data corresponding to a cell stripe of scanning over which continuous exposure is possible. When the checksum is calculated after expanding the data into the bitmap, the interim calculation result of refocus values is used. In exposure, exposing k number of sub rectangular areas by repeating a sub scanning k number of times, jumping a deflection by a main deflector toward an center of remaining sub rectangular areas whose number is (p-k) inside a main rectangular areas and exposing remained (p-k) number of the sub rectangular areas by repeating the sub scanning (p-k) times after the jumping is settled. In an amplifier & low pass filter for supplying a drive voltage to a sub deflector, the cutoff frequency is lowed during flyback in a sawtooth waveform without changing an amplification factor.

FIELD OF THE INVENTION The present invention relates to a volume controller which is used in sound processing circuits, etc., and more particularly to a volume controller for logically controlling sound volume like a bus line sound processor IC. BACKGROUND OF THE INVENTION Conventionally, various audio ICs have been developed by a method, such as a spectrum analysis of audio frequency. The sound volume or tone quality of a sound source has been studied based on an audio signal transmission system, for instance, a human hearing organ or a signal transmission medium. It is generally said that if the volume level of a sound source is attenuated by 20 dB, the sound is heard by the human hearing organ at nearly half the volume level. This relationship is expressed numerically by the following logarithmic expression: Expression 1! A=-20·log.sub.10 X where, A is the hearing sensitivity and X is the sound source intensity. A circuit conforming to this characteristic may be said to be an ideal sound volume controller. An ideal volume control curve is shown in FIG. 1. The Y-coordinate shows volume attenuations and the X-coordinate shows gradations. A typical circuit used in a volume controller IC is shown in FIG. 2. This circuit regulates sound volume by setting the control current ICONT which will be explained later with reference to the drawings. An input audio signal IN from a sound source AC1 is amplified in a differential amplifier circuit 11 which is comprised of an emitter resistor RE commonly connected to the emitters of respective transistors, a current source IO, and a load resistor RL to provide an output audio signal OUT. The collectors of transistors Q9, Q10 of the differential amplifier circuit 11 are commonly connected to a DC power source Vcc via differential circuits 12a, 12b of a bias regulating circuit 12. The differential circuits 12a, 12b for biasing are provided with two pairs of transistors Q5-Q6 and Q7-Q8, a DC power source Vcc to be connected to the collectors of the transistors Q6 and Q7, collector-base connected diodes Q2, Q3 connected to the collectors of transistors Q5, Q8, and transistors Q1, Q4 of which bases are connected to the diodes Q2, Q3 and their emitters are connected to the DC power source Vcc. The emitters of transistors Q11, Q12 which promote the external load driving capacity are connected to a reference potential and their bases are connected to the emitter of a transistor Q13. The base of transistor Q13 is connected to the collector of transistor Q11 and the collector of transistor Q13 is connected to the DC power source Vcc. The bases of transistors Q5-Q8 in the bias regulating circuit 12 are connected to a reference current circuit 13 that provides a reference current Iref, control current setting circuits 14a, 14b which are set by the control current ICONT, and base potentials VB1, VB2 which are set by the reference current Iref and the control current ICONT, respectively. The reference current circuit 13 is provided with collector-base connected diodes Q19-Q23 which are connected to the DC power source Vcc and the reference current source Iref, and is comprised of a transistor Q26 whose base is connected to the reference current source Iref, collector is connected to the reference potential source, anD emitter is connected to two stack-connected diodes Q24, Q25; a resistor R3; and the DC power source Vcc. The emitter voltage VBl of transistor Q26 of the reference current circuit 13 is supplied to the base of transistor Q5 of the differential circuit 12a of the bias regulating circuit 12 and the base of transistor Q8 of the other differential circuit 12b via the diodes Q24, Q25. Similar to the reference current circuit 13, the control current setting circuit 14a is provided with a constant current source comprising a transistor Q31 and five stack-connected diodes Q14-Q18. The base current of transistor Q31 is controlled by the control current ICONT, while the emitter voltage of transistor Q31 regulates a voltage VB2 which will be described later. Further, the control current setting circuit 14b is comprised of two stack-connected diodes Q27, Q28, a transistor Q29 and a resistor R4, which are connected in series. The node connecting diode Q27 and resistor R4 is connected to the bases of transistors Q6, Q7 of the differential circuits 12a, 12b. A volume control circuit 10 attenuates the weighted sound volume by approximately 20 dB when the volume level is suppressed from the maximum level to the medium level. If the volume is further suppressed lower than the medium level, the volume control circuit 10 sharply attenuates the sound volume. This is because if there is insufficient attenuation, a residual sound is heard. In order to eliminate this residual sound, the two series of the collector-base connected diodes Q14-Q18 and Q19-Q23 are each stacked in five layers. Hereinafter, potential relations of PN junction systems will be explained in detail based on electronic physical properties. It is assumed that the collector current of a bipolar transistor is IC; the saturated current of a PN junction in the reverse direction is IS; the coefficient of heat of molecular motion, Boltzmann's constant, is K; the absolute temperature, expressed in Kelvin, is T; the electronic charge is q; voltages between collector, base and emitter are expressed by adding a subscript of C for collector, B for base and E for emitter (for instance, VBE denotes the base to emitter potential); the reference current source is Iref; the control current is ICONT; and the emitter to collector current amplification factor of a bipolar transistor is α. If input voltages of the differential circuits 12a, 12b are VB1, VB2 (see FIG. 2), the following relationships are established: ##EQU1## Calculating a difference according to the above expression yields: ##EQU2## Further, when the current characteristic of the PN junction system is expressed by the following exponential function: ##EQU3## the following expression is calculated: ##EQU4## The DC voltage and the collector output signal are fed back to the base of the transistor Q10 of the differential amplifier circuit 11 via the load resistor RL. The amplification gain of the audio signal is calculated according to the emitter resistor RE, the load resistor RL and the emitter current, i.e., the ratio of the current source IO to the collector current IC derived from the above equation 5. The gain expression converted into the decibel unit is shown as follows: ##EQU5## From the above expression, it can be seen that Iref/Icont -1.55 is sufficient for achieving an attenuation of 20 dB. If the attenuation characteristic is set using Iref/Icont=1.55 as an intermediate value as shown by the solid line in FIG. 3, the control current ICONT changes linearly. Therefore, minimum and maximum values are decided uniquely. Thus the maximum current ratio will become 0.775 while the amount of the attenuation will become 2.41 dB. As shown by the dotted line in FIG. 3, if the attenuation characteristic is set so that the control current ICONT reaches its maximum value at three times its intermediate value the attenuation at the maximum value is improved to 0.31 dB. However, a problem arises when the minimum value of the control current ICONT does not correspond to the minimum volume level which falls outside the operation range causing the dead zone to extend up to near the intermediate value. A method of addressing this problem is to increase the gain by increasing the value of the load resistor RL. However, considering thermal noise of resistors, impedance mismatch and the noise characteristic of feedback paths, this method is also problematic because increasing the load resistor RL deteriorates the noise characteristic and increases the residual noise. In addition, an amount of a DC offset component, i.e., an error component of input and output signals, is increased by increasing the load resistance RL. Therefore, increasing the load resistance RL becomes disadvantageous to overall operating characteristic. Further, decreasing the emitter resistance RE not only decreases the minimum input sensitivity, but also decreases the input dynamic range. Therefore, the bias current must be increased which results in further problems such as increased current consumption and increased DC offset. After improving the attenuation rate based on the load resistor RL and the emitter resistor RE, there are still such problems that not much improvement is obtainable. Even at the maximum volume level there is a data loss (e.g., 2.91 dB) which increases the noise level. When the control current has a linear characteristic it is also impossible to improve the gain loss at the maximum volume without deteriorating circuit characteristics. As described above, in the conventional circuit, as a sound volume is varied by linearly changing the control current, it is impossible to simultaneously improve such operating characteristics as reduction of the gain loss at the maximum volume, expansion of the input dynamic range, noise reduction, etc. SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide a volume controller which compensates for the shortage of control current at a maximum volume level, suppresses gain loss and expands dynamic range. In order to achieve this object, a volume controller according to a first aspect of the present invention includes a volume regulating circuit having an input terminal connected to an audio signal source and a control terminal to which a volume regulating voltage is supplied; a circuit for supplying parallel data in multiple bits; a DIA conversion circuit having multiple current circuits formed in parallel corresponding to each bit of the parallel data for ON/OFF controlling of the current circuits according to respective bit data and for supplying total sum current flowing through these current circuits; a control circuit for controlling output current from the D/A conversion circuit to non-linear current by switching current levels of respective current circuits corresponding to the most significant bit of the parallel data; and a circuit for generating the volume regulating voltage by converting the output current from the D/A conversion circuit into voltage. Further to the first aspect of the invention a volume controller according to a second aspect of the present invention includes a first and a second transistors comprising a differential circuit by commonly connecting the emitters; a first constant current source connected to the emitters of the first and the second transistors, the base bias source for the first and the second transistors, and a circuit for switching the ON/OFF state of the first and the second transistors by controlling the base voltage of the first transistor corresponding to bit data; and the collectors of the first transistors of the current circuits connected to a DC voltage source and the collectors of the second transistors connected with each other to obtain the output current. Further to the first aspect of the invention, a volume controller according to a third aspect of the present invention includes a third and a fourth transistors comprising a differential circuit by commonly connecting their emitters; a second constant current source connected to the emitters of the third and the fourth further transistors, the base bias source for the third and the fourth transistors; a circuit for switching the ON/OFF state of the third and the fourth transistors by controlling the base voltage of the third transistor corresponding to the most significant bit data; a first current mirror circuit connecting the input terminal to the collector of the third transistor and a second current mirror circuit to which the output current of this first current mirror circuit and the current from a third constant current source is supplied as an input current; and a current volume of respective current circuits is determined by the output current of the second current mirror circuit. A volume controller according to a fourth aspect of the present invention includes a volume regulating circuit having an input terminal connected to an audio signal and a control terminal to which a volume regulating voltage is supplied; a circuit for supplying parallel data in multiple bits; a D/A conversion circuit including the parallel data supply circuit and multiple current circuits formed in parallel for every bit of the parallel data for setting currents flowing through the current circuits sequentially at different values and for supplying a total sum current flowing through these current circuits as the output; a control circuit for switching the magnitude of the currents from the current circuits corresponding to the most significant bit of parallel data and for controlling a change characteristic of the output current from the D/A conversion circuit to non-linear in a first and a second regions; and a circuit for generating the volume regulating voltage by converting the output current from the D/A conversion circuit into voltage. According to the present invention it becomes possible to suppress the gain loss at the maximum volume level and expand the input dynamic range from the minimum volume level to the maximum volume level by appropriately setting a reference current in a D/A converter and controlling the reference current using a controller. Additional objects and advantages of the present invention will be apparent to persons skilled in the art from a study of the following description and the accompanying drawings, which are hereby incorporated in and constitute a part of this specification. BRIEF DESCRIPTION OF THE DRAWINGS A more complete appreciation of the present invention and many of the attendant advantages thereof will be readily obtained and better understood by references to the following detailed description and accompanying drawings, wherein: FIG. 1 is a diagram showing an ideal volume control characteristic; FIG. 2 is a circuit diagram showing a conventional volume controller; FIG. 3 is a diagram showing the control current characteristic of a conventional volume controller; FIG. 4 is a circuit diagram showing one embodiment of the volume controller according to the present invention; FIG. 5 is a diagram for explaining the operation of the D/A converter shown in FIG. 4; FIG. 6 is a diagram showing the control current characteristic of the volume controller shown in FIG. 4; FIG. 7 is a diagram showing the volume characteristic of the volume controller shown in FIG. 4; FIG. 8 is a circuit diagram showing another embodiment of the volume controller according to the present invention; FIG. 9 is a diagram showing the volume characteristic of the volume controller shown in FIG. 8; FIG. 10 is a circuit diagram showing another embodiment of the volume controller according to the present invention; and FIG. 11 is a diagram showing the volume level characteristic of the volume controller shown in FIG. 10. DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with references to FIGS. 4 through 11. FIG. 4 is a preferred embodiment of a volume control circuit according to the present invention. The elements in FIG. 4 that are the same or similar elements as those in FIG. 2 are assigned the same reference numerals and explained with these reference numerals. In FIG. 4, a volume control circuit is provided with a volume control circuit 10, a D/A converter 20 and a nonlinear controller 30 for controlling a control current with a nonlinear characteristic. The column control circuit 10 is in the same structure as a conventional volume control circuit and control current is controlled by the nonlinear controller 30. The nonlinear controller 30 is comprised of a constant current source and a switching circuit 31. The constant current circuit is comprised of a differential circuit provided with a pair of transistors Q49, Q50; a DC power source Vcc; transistors Q46, Q52, Q53 comprising a constant current source; resistors R17, R20; a transistor Q48 configured in a collector-base connected diode fashion, which is connected to the collector of the transistor Q50 of the differential circuit; and a transistor Q47 having the base connected to the base of the transistor Q48 and the collector connected to a reference current circuit 21. The switching circuit 31 is connected to the base of a transistor Q49 of the differential circuit Q49/Q50, while a DC power source V2 is connected to the base of the other transistor Q50 of the differential circuit Q49/Q50. The switching circuit 31 is comprised of another DC power source V1, a resistor R18, a switching transistor Q51, a resistor R19 and a gate circuit G1. The DC power source Vi is connected to the collector of the switching transistor Q51 via the resistor R18. The emitter of the transistor Q51 is then connected to a gate circuit G1, for instance, an open collector type inventor circuit, via the resistor R19. The base of the switching circuit Q51 is connected to another DC power source V3. The switching circuit 31 is provided for receiving a most significant bit (hereinafter referred to as MSB) of a parallel data bus. The reference current circuit 21 is comprised of a reference current source II, a diode-fashion transistor Q45 and a resistor R16. Further the reference current source Ii is comprised of a bias setting circuit and a transistor Q44. The bias setting circuit is provided with a diode-fashion transistor Q43 connected to the base of the transistor Q44, an emitter-grounded transistor Q42, and a bias circuit for the transistor Q42 which is comprised of resistors R13, R14 and diode-fashion transistors Q40, Q41. Further, the D/A converter 20 is provide with the nonlinear controller 30, the reference current circuit 21, constant current circuits 22-27 and the DC power source Vcc. Each of the constant current circuits 22-27 is provided for a corresponding bit of the parallel data bus. The sum of the constant current circuits 22-27 in the parallel data bus provide the control current ICONT. Further the control current value ICONT can be set for any constant current value of a least significant bit (hereinafter referred to as LSB). The constant current circuit 22 corresponds to the LSB, while the constant current circuit 27 corresponds to the MSB. The constant current circuits 22-27 include constant current sources I2-I7, respectively, which are comprised of transistors Q45-65 coupled in five sets of differential circuits, switching circuits 22a-27a, resistors R22-R27 and transistors Q66-Q71. Starting from the constant current source I2, currents with two times value are sequentially set in the constant current sources I2-I7, thus for example a current with 16 times the current of I2 is set for the constant current source I6. The constant current circuits 22-27 for respective bits are connected to the DC power source Vcc via a diode-fashion transistor Q100 and the resistor Rl in order to control the control current value ICONT of the volume control circuit 10. The diode-fashion transistor Q100 is connected to the base of a transistor Q200 of the control current setting circuit 14a. Thus the control current ICONT flows from the DC power source Vcc via the emitter-collector path of the transistor Q200 in response to the change in the current from the D/A converter 20. The control current ICONT sets the base voltage VB2 on the bases of the transistors Q6 and Q7 in the adjacent differential circuits Q5/Q6 and Q7/Q8 in the bias setting circuit 12 connected to the collectors of the transistors 09, Q10 of the differential amplifier circuit 11. The operation of the volume control circuit 10 of FIG. 4 is understood by referring to FIG. 2. FIG. 5 is an explanatory diagram illustrating the operation of the D/A converter of the volume control circuit shown in FIG. 4. FIG. 6 is a graph showing the control current characteristic of the circuit shown in FIG. 5. In FIG. 5, the current sources in the reference current circuit 21 and the nonlinear controller 30 are shown by I2-I7 and I1. The switching circuit 31 in the nonlinear controller 30 and the switching circuits 22a-27a in the constant current circuits 22-27 are shown by the switches SW1-SW7, respectively. The ON/OFF states of the switches SW1-SW7 are controlled by parallel bit data. The LSB of a 6-bit data is supplied to the switch SW2, while the other bits higher than the LSB are sequentially supplied to the switches SW3-SW6. Thus the MSB data is supplied to the switch SW7. Each of the switches SW1-SW7 are turned ON when their corresponding data bit is "1", or turned OFF when the corresponding data bit is "0". Further, it is so provided that the values of the constant current sources I2, I3, . . . I6 sequentially increase by two times such that I3=2×I2, I4=2×I3, . . . I6=2×I5. In FIG. 5, if the bit data supplied to the switches SW1-SW7 are all "0", the switches SW1-SW7 are turned OFF so that the transistors Q49, Q54, Q58, Q60, Q62 and Q64 are turned ON. While in that state with the transistors Q50, Q55, Q57, Q59, Q61, Q63 and Q65 being left in the OFF state, no current flows through the transistor Q100. Accordingly, the control current is set to zero current. Further when only the least significant bit (LSB) is "1", only the switch SW2 in the constant current circuit 22 is turned ON. As a result a current equal to the current I2 flows through the transistor Q100. In the same manner, the constant current I3-I6 flow through the transistor Q100, in response to the corresponding bit data applied thereto. That is, the total amount of the currents I3-I6 flows through the transistor Q100. Further, when the most significant bit (MSB) becomes "1", the switches SW1 and SW67 are turned ON. Then the transistor Q49 is turned OFF but the transistor Q50 is turned ON. Thus a current flows through the transistor Q45 based on the current-mirror connection due to the current mirrors Q48, Q47 between the transistor Q45 and Q50. The current of the transistor Q45 is given by the sum of the constant current I1 and the current flowing through the transistor Q47. Accordingly, the current becomes twice the amount of the constant current I1. Then, currents flowing through the transistors Q66, Q67, Q68, Q69, Q70 and Q71 which constitute similar current-mirrors, respectively, in connection with the transistor Q45, become also twice the constant current Il. When the MSB becomes "1" (the medium point of 64 tones), the current flowing through the transistor Q100 so increases that the control current ICONT has a characteristic as shown in FIG. 6. If the current flowing through transistor Q45 in the referenced circuit 21 is 100 μA when switch SW1 is OFF the minimum current value of the D/A converter 20 (i.e., the resolution of the D/A converter 20) is a value obtained by dividing the reference current value by the number of data values that can be achieved using all bits but the MSB of the parallel data; that is, a value given by 100÷=3.135 μA for six bit data. On the other hand, when the switch SW1 is ON, that is, the MSB is high, the reference current becomes 200 μA, a sum with the current value 100 μA of the constant current circuit and the minimum current set value of the D/A converter 20 will become the value given by 200÷=6.25 μA. Thus, it becomes possible to obtain the control current characteristic, as shown in FIG. 6, by turning OFF the switch SW1 for the lower volume range and turning ON the switch SW1 for the volume range from the medium volume to the maximum volume. Further, an exemplified volume characteristic, as shown in FIG. 7, is also obtained. An attenuation of 20 dB is achieved at a point around the medium section. At the maximum volume it becomes possible to flow a current of 300 μA determined by the total sum of all bits. Thus, the gain loss at the maximum volume can be reduced. The dotted line in the graph plots an ideal volume characteristic curve and the solid line plots a volume characteristic curve of the embodiment of the volume control circuit according to the present invention. Point A indicates the changing point of the ON and OFF areas of the switch SW1. FIG. 8 shows another preferred embodiment of the present invention. This is an example of data modified from the 6-bit data to a 7-bit data. Except that a circuit for one bit is added, this embodiment is entirely the same as the embodiment as already described above. That is, a constant current circuit 28 (including transistors Q78, Q81 and Q82) associated with the MSB of the 7-bit data is newly added. According to the above arrangement, it becomes possible to increase data values presented by the parallel data and thus increase a current value at the maximum volume level. Thus the gain loss is further decreased. FIG. 9 shows a graph illustrating the volume control characteristic of the second embodiment of FIG. 8. This graph shown an example of using 100 tones out of 128 data values presented by the 7-bit data. The dotted line in the graph plots an ideal level characteristic, while the solid line plots a practical volume level characteristic of the second embodiment. Further, FIG. 10 shows a third embodiment of the volume controller according to the present invention, in which two series of four stack-connection diodes Q14-Q17 and Q19-Q22 are used in the circuits associated with the residual sound, in place of the five stack-connection diodes Q14-Q18 and Q19-Q23. In this case, a gain is calculated by changing the exponential portion of Expression 3 in the conventional embodiment from 5 to 4. Although the circuit size of this embodiment increases as required to the embodiment in FIG. 4, the lower volume area characteristic is also improved as shown in FIG. 11. The effect of the characteristic enhancement resulting form the improvement of amplifiers in the volume controller according to the present invention are presented in the following table. ______________________________________ BEFORE AFTER IMPROVINGITEM IMPROVEMENT IMPROVEMENT RATE______________________________________Load resistance 14.2 KΩ 2.0 KΩ --Noise level 1.84 E-5 V 1.39 E-5 V 2.44 dbResidual noise 1.52 E-8 V 1.84 E-5 V 0.71 dbOffset 42 mV 38 mV 9.5%______________________________________ As seen from the above table, as a result of the improvement of the amplifier efficiency, not only is the characteristic deterioration caused by the improvement of load resistances or emitter resistances eliminated, but it is possible to reduce the load resistance. In the embodiments as described above, the noise level caused by load resistance has been highly reduced (Improving rate: 2.44 dB). The DC offset has been highly reduced (Improving rate: 9.5%). Also the residual noise has been reduced (Improvement rate: 0.71 dB). As described above, the present invention can provide an extremely preferable volume controller. That is, the volume controller according to the present invention is able to improve the S/N, reduce the residual noise and reduce the DC offset by controlling the performance of the amplifier circuit in the volume control circuit by non-linearly setting the control current. While there have been illustrated and described what are at present considered to be preferred embodiments of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made, and equivalents may be substituted for elements thereof without departing from the true scope of the present invention. In addition, many modifications may be made to adapt a particular situation or material to the teaching of the present invention without departing from the central scope thereof. Therefore, it is intended that the present invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out the present invention, but that the present invention includes all embodiments falling within the scope of the appended claims. The foregoing description and the drawings are regarded by the applicant as including a variety of individually inventive concepts, some of which may lie partially or wholly outside the scope of some or all of the following claims. The fact the applicant has chosen at the time of filing of the present application to restrict the claimed scope of protection in accordance with the following claims is not to be taken as a disclaimer or alternative inventive concepts that are included in the contents of the application and could be defined by claims differing in scope from the following claims, which different claims may be adopted subsequently during prosecution, for example, for the purposes of a divisional application.

A volume controlire include a volume regulating circuit having an input terminal connected to an audio signal source and a control terminal to which a volume regulating voltage is supplied. a circuit for supplying parallel data in multiple bits. a Df/A conversion circuit having including multiple current circuits formed in parallel corresponding to every bit of the parallel data, for ON/OFF controlling the current circuits according to respective bit data and for supplying total sun current flowing through these current circuits, a control circuit for controlling output current from the D/A conversion circuit to non-linear current by switching current volumes of respective current circuits corresponding to the most significant bit data out of the parallel data, and a circuit for generating the volume regulating voltage by converting the output current from the D/A conversion circuit into voltage.

FIELD OF THE INVENTION [0001] This invention relates to a golf tee specifically designed to minimize the forces of friction and shear between the golf tee and the golf ball when the ball is struck by a golf club thereby maximizing the transfer of energy and momentum from the golf club head to the ball. BACKGROUND OF THE INVENTION [0002] In the ever increasingly technical world the sport of golf has seen its share of innovations in the last few decades. Most of these have been aimed at either the golf ball or the golf club with a smaller number directed to the golf tee. Although a number of patents have been written for tee designs, very few have considered the golf tee as a source of improved distance and ball flight. In U.S. Pat. Nos. 5,683,313 and 5,413,330 Thomas Disco and Charles Parish disclose a Vented Golf Tee design. Venting the golf tee is done to reduce the suction between the surface of the golf tee and the golf ball upon impact with the club head. In U.S. Pat. No. 5,505,444 Edward Bouclin disclosed a flat head tee designed to reduce friction. In this patent an adhesive material must be applied to keep the ball from rolling off the tee. One might question whether the adhesive force negates any benefit from the reduced surface area. [0003] In U.S. Pat. No. 6,053,822 Jeffery Kolodney discloses a tee with a ring of bristles coming up to hold the ball in place. In U.S. Pat. No. 6,004,228 John Adam discloses a Vented Angular Golf Tee, another design to work on eliminating the suction between the ball and the tee. All these designs have merit in that they recognize that there are forces at play between the ball and the tee that can be reduced, altered, or re-directed. Accordingly, it is one object of my invention to minimize forces associated with the tee that act to resist the energy transferred to the ball from the golf club at impact, while at the same time keeping the end product practical to use and purchase. [0004] Minimizing the effect of forces associated with the tee produces longer flight distances and more initial ball spin due to the club head acting on the ball. These benefits are a primary object of the invention and are especially desirable for the long shot, where the ability to advance the ball takes precedence. In addition, the short shot where maximum backspin helps to stop the ball quickly on the green is improved. These and other benefits and objects are achieved by my invention which is described in the summary of the invention and detailed description below. SUMMARY OF THE INVENTION [0005] I have surprisingly discovered that the flight distance and spin of a golf ball are increased by reducing the surface friction of the surface of the golf tee on which the golf ball rests. Thus, in one aspect, my invention is the process of reducing surface friction of the support surface of a tee by application a coating or a layer of low friction material or low surface tension material comprising, for example, a fluorochemical material or a fluorocarbon resin such as polytetrafluoroethylene, perfluoroalkoxy material or their copolymers. The entire tee may be made from a low friction material or only the head or a cap on the head may be made from low friction material. [0006] In another aspect, my invention comprises a tee with a support surface coating of such resins and the support surface area has been reduced to the least amount of surface area practical. My invention also comprises the method of making such a tee. DESCRIPTION OF THE DRAWINGS [0007] In the drawings appended hereto and made a part of this disclosure: [0008] [0008]FIG. 1 is a top plan view of a golf tee representing of one preferred embodiment of the present invention; [0009] [0009]FIG. 2 is a side view of the embodiment of FIG. 1; [0010] [0010]FIG. 3 is a perspective side view of showing a partial golf ball positioned on a prior art tee; [0011] [0011]FIG. 4 is a sectional view of the embodiment of FIG. 2 but with a golf ball positioned on the tee; and, [0012] [0012]FIG. 5 is a side elevation in section of preferred embodiment of the present invention showing a golf ball tee in position. DETAILED DESCRIPTION [0013] My invention deals with three factors in improving tee performance: [0014] 1. The surface material of the tee where the ball is intended to rest; [0015] 2. The minimal surface area of the tee needed to contact the ball; and, [0016] 3. The shape of contact area to minimize shear effects during a tee shot. [0017] The frictional forces acting when an object is resting on a surface can be represented by the equation: F=W×SA×CoF where F is the force of friction, W is the weight of the golf ball (which is a constant), SA is the surface area of contact, and CoF is the coefficient of friction of the surfaces. [0018] In the case of the golf ball the CoF can change depending upon the cover material used in its construction. Generally, harder balls known for their distance have lower CoF=s than softer covered balls. In the case of the surface of the tee, the preferred support surface material in my invention is polytetrafluoroethylene, or PTFE, which is sold under the brand name Teflon7 (DuPont=s trademark for this polymer material) as the surface of choice. This material or similar materials such as FEP (fluorinated ethylene propylene copolymer), PFA (perfluoroalkoxy), or ETFE (ethylene/tetrafluoroethylene copolymer) have the lowest coefficient of friction of generally available and usable materials. All contain fluorine in their chemistry. In addition they are known for providing non-stick surfaces. [0019] Terms such as fluoropolymer, fluoroplastic, fluorocarbon resin, or fluorohydrocarbon resin may be used in this specification as the preferred fluorine containing compositions are those which produce low friction surfaces or low surface tension surfaces. These composition include those compositions known as :fluorochemicals.@ In general, compositions which exhibit low surface friction are within the scope of my invention. Low friction tends to be more important when the golfer is using balata or other soft covered balls that are composed of low Tg (Glass Transition Temperature) polymers that have a tendency to self adhere more easily to other surfaces than harder polymers such as those made from the ionomers sold under the brand name Surlyn7 also sold by DuPont. [0020] Considering the surface area, most conventional or prior art tees are made more or less the same. They consist of a bowl having a diameter of approximately 10 to 13 mm. to the outer edge. In addition, this bowl shape generally has a ball conforming shape ending abruptly at the edges. From a manufacturing standpoint it is clear to see that this shape offers the golfer the greatest ease when sticking the tee in the ground and mounting a golf ball on it. However, from a frictional standpoint, the smaller the surface area of contact, the better. The smallest area of contact would be a single point, but this would make it virtually impossible for the golfer to mount the ball. In addition, the hand held ball-and-tee combination is used by many golfers for guidelines and additional force when sticking the tee in the ground and a very small point would be next to impossible to use. Obviously, any change in the shape of the tee head would have to take into consideration these things to be accepted by the typical golfer. Golfing can be frustrating enough without having to worry about mounting the golf ball on the tee. [0021] Referring now to FIG. 1, a top plan view of the tee 1 is shown. The minimum acceptable surface area can be achieved with three points or nobs 2 equal distance apart defined by the dotted line circle 3 in FIG. 1. It has been discovered that the minimum diameter of the center of the circle is preferably in the range of 5 to 9 mm. If the diameter is less, substantial difficulty is encountered in mounting the ball. Points defined by a larger circle can be used, but shear forces come in to play as described below. In addition, the support points 2 should be preferably short and stubby in configuration to stabilize the ball's position when using the golf ball to stick the tee into the ground. A side view of golf tee 1 with head 4 is shown in FIG. 2 with support nobs 2 having the configuration mentioned. [0022] In addition to frictional forces there are shear forces SF acting on a golf ball that also reduce energy transferred from a club head which strikes the ball (See FIGS. 3 & 4). The shear forces SF is the resistance to the initial movement of ball 5 direction against the edge 6 of the perimeter of the tee head. A smaller, more rounded perimeter will provide a smaller surface area thus reducing the total frictional resistance. Having a shallower resting area will help to minimize the shear force SF since less of the weight WB of the ball is beneath the edge 6 . In addition, a rounded smoother edge will produce less shear force than a sharper more knife like edge. This effect may explain to some extent the longer distances and better trajectories that are seen with the balls hit by professional golfers because in a pro swing the club head contacts the ball on the upswing, and the force imparted has a lower horizontal component of the shear force SF. This force as illustrated in the center slice view of conventional ball and tee in FIG. 3 shows why an upswing hit is affected less by the shear force than a straight horizontal swing represented by FC. An embodiment of my invention to minimize these forces is illustrated in center slice view of the ball and tee in FIG. 4. It can be understood that a golfer with a swing that contacts the ball on the downward swing would tend to benefit more from this embodiment, due to the greater shear force SF imparted with this swing which would impart a vertical component to the force vector. [0023] In the embodiment of a tee as described above the tee would preferably be made out of pure PTFE by molding or machining, Example 9 but the expense may be unacceptable to the average player. To overcome the problem of expense and provide the advantages of reduced resistance the following examples were disclosed. EXAMPLE 1 [0024] The resting surface of a standard wooden tee was coated with a fluorosurfactant, DuPont's Zonyl, to lower the surface tension and friction of a ball resting on it. [0025] Observations: The low molecular weight material is easily sheared off and appears to only last 1 or 2 hits. Also, some material may be transferred to the ball and subsequently the club face which violates the following USGA rules: Rule 4-3. Foreign Material [0026] Foreign material must not be applied to the club face for the purpose of influencing the movement of the ball. Penalty is Disqualification. [0027] Rule 5-2. Foreign Material [0028] Foreign material must not be applied to a ball for the purpose of changing its playing characteristics. Penalty is Disqualification. EXAMPLE 2 [0029] A conventional wooden tee conventional according to FIG. 5 was used. The FIG. 4 tee could also be used. Surface areas were reduced so that counterpoint 111 is on a circle with a diameter similar to the diameter of the circle in FIG. 1. The edge of the tee=s surface is rounded instead of sharp as shown by the surface from point 111 to edge 112 . The surface was coated with a DuPont Aqueous Teflon BS Coating, such as available in the 954 series. This is a water dispersion of Dupont Teflon that requires baking to coalesce the polymer particles to a continuous film. Once the coating is applied, baking is done at 350 to 500 degrees F., for 15 to 30 minutes. [0030] Results: Baking a wooden tee causes the tee to become more brittle so that it does not last as long. In addition, unless the film is cast several mills thick the shear of the golf ball coming off the tee during the tee shot abrades the thin film away after only a few shots. EXAMPLE 3 [0031] A conventional wooden tee which also could be one modified as in FIG. 5 to reduce the surface area and sharp edges was coated with a DuPont Teflon S coating such as 958-303 or 958-313, a solvent based dispersion of Dupont Teflon that requires baking to coalesce the particles to a continuous film. Once the coating is applied the baking is done at 400 to 600 degrees F., for 15 to 30 minutes. [0032] Results: Baking continued to be+a problem with the wooden tee. The finished coating is more durable than the water based coating however, a rounded contact surface is still needed to maintain the surface integrity through several shots. EXAMPLE 4 [0033] The wooden tee as before was wrapped with a coil film crimped over the head. The coil film has been coated and baked with the DuPont Teflon dispersions used in Examples 2 and 3. [0034] Results: The force of the club head striking the ball also strikes the head of the tee. This force caused crimping of the coil and failure after only a few hits. EXAMPLE 5 [0035] The procedure as in Example 4 and 5 was used where the back side of the coil is treated with a pressure sensitive adhesive to adhere to the tee head. [0036] Results: Although this method seemed to hold up better with several tee shots possible, the abrasion of the club head to the back edge of the surface caused failure in the range of 4 to 6 hits. EXAMPLE 6 [0037] A wooden tee as in the previous examples is capped with a metal coil bent and cut to the shape shown in FIG. 5. As used herein, Acoil@ means a relatively thin metal sheet of greater thickness that the common thickness of metal foil. The metal coil was pre-coated with the DuPont Teflon dispersions mentioned in Examples 2 and 3 and baked at 400 to 600 degrees F. for 15 to 30 minutes to coalesce the particles into a continuous film. The shaped coil part was adhered to the wooden tee with a pressure sensitive adhesive. The coil must be of a soft metal such as aluminum, zinc, copper, or brass to prevent damage to the club head at impact. [0038] Results: The force of the club head striking the metal piece was enough to dislodge it after only a few shots. The metal piece in some cases was separated from the tee and launched with great velocity. Such a projectile could represent a danger to the golfer or other people on the course. EXAMPLE 7 [0039] The procedure as in Examples 6 and 7 where the metal coil is pre-coated with the DuPont Teflon dispersions mentioned in Examples 2 and 3 and baked at 400 to 600 degrees F. for 15 to 30 minutes to coalesce the particles to a continuous film was used. The cut and shaped coil part was adhered to a wooden tee using a small #4 wood screw. [0040] Results: This configuration worked well for several shots. However failure occurred usually due to the splintering of the wood tee around the screw again causing the metal coil and/or wood screw to be launched at a significant velocity. Such a projectile could represent a danger to the golfer or other people on the course. EXAMPLE 8 Preferred Embodiment [0041] Several samples of TFPE tape backed with a pressure sensitive adhesive were obtained from Enflo. These samples differed in their thickness and ranged from 0.10 mils to 0.30 mils. Wooden tees were prepared by removing the painted surface from a conventional wooden tee. In addition some tees were shaped to reduce the surface area as in FIG. 5. The Enflo tape was cut to fit the tee=s shape and applied with pressure. The adhesive was allowed to set for 24 hours. [0042] Results: This embodiment was the most practical and economical approach of the foregoing example. The higher mil thickness tapes had too much memory and were difficult to form on the tee head. However, even the 0.10 mil film lasted at least 15 to 20 hits. It was also noted that the thicker films tended to become compressed and deformed more readily than the thinner films. EXAMPLE 9 [0043] A cylinder of pure PTFE was turned and shaped to produce another preferred embodiment of an improved golf tee. The shape of the head conforms to the top and side views of FIG. 1 and FIG. 2. [0044] Result: While injection molding would be a preferred mass production technique to produce the tee of this embodiment, tooling would be necessary to make the injection mold. The cut part represents effectively the same part that would have been produced by injection molding. [0045] In this preferred embodiment, not only has surface friction been reduced by the use of a Teflon based material, the surface has also been reduced to the contact made by the three support prongs or nobs 2 . The prongs being set at 120□ provide a sure and stable resting support for the ball. The diameter of the circle around which the nubs were positioned was about 8 mm. EXAMPLE 10 [0046] A wooden tee was dipped in molten PTFE in an attempt to get a uniform coating on the head. [0047] Result: Although other thermoplastic materials like polyethylene or polypropylene work with this technique, the viscosity of molten PTFE was too high to effectively form an adhering coating. In addition, the high temperature needed to melt PTFE to a fluid or liquid condition were too high for a practical process. Tests [0048] The tee described in Example 8 was used for comparison against a conventional wooden tee with no modifications. Several tests were conducted to determine if the tee gave an increase in performance as measured by an increase in distance with the tee shot. [0049] Test 1 B Using a 5 wood of 21 degrees of loft ten shots were hit with range balls mounted on a standard tee and on the tee of Example 9. The 5 wood was chosen for consistency off the tee. The 5 best shots from each group were taken and measured for overall distance using a laser range finding scope with an accuracy of +/−1 yard. The results are in the following table: Yards with Standard Tee Yards with Tee of Example 9 1 187 193 2 202 191 3 193 200 4 186 205 5 201 194 Average 193.8 196.6 [0050] This embodiment yielded an increase in distance of 1.44%. For a 250 yard drive this could amount to 3.6 yards. [0051] Test 2 B Using a 5 wood of 21 degrees of loft, several shots were hit with both hard covered distance balls and soft covered balata balls. The 5 wood was chosen for consistency off the tee. Both carry and carry plus roll were measured using a laser range finding scope. The results are in the following tables: Using Top Flite XL Distance Balls Carry Carry and Roll Regular Tee 172.6 yards 182.6 yards Tee of Example 9 176.4 yards 190.0 yards Difference  3.8 yards  7.4 yards Using Titleist Tour Balata Balls Regular Tee 166.3 yards 174.7 yards Tee of Example 9 170.0 yards 182.8 yards Difference  3.7  8.1 yards [0052] In both cases whether a hard covered or soft covered ball was used an increase in carry of 2.2% was achieved. Carry and Roll were improved slightly better with the soft covered balls. [0053] The foregoing results demonstrate that reduction in friction and forces and resistance due to the tee shape do improve performance. [0054] In another embodiment the entire tee can be made of PTFE so that a cover 114 as shown in FIG. 5 is not required. FIG. 4 shows still another embodiment wherein the projections 11 and upper surface of the tee 10 are covered with a PTFE cover 12 . The head 14 and shaft 13 are made of wood. Again, the entire tee can be made of PTFE eliminating the need for cover 12 . [0055] The foregoing description of the embodiments of my invention are by way of illustration and not limitation. My invention is limited only by the scope of the claims below:

An improved golf tee having a ball support surface that reduces the frictional resistance of the tee when the ball is struck thus lengthening the distance a ball can be driven. A friction reducing material such as a fluorochemical or flouropolymer comprises the support surface.

CROSS REFERENCE TO RELATED PATENT APPLICATION [0001] The current application claims the benefit of the earlier priority filing date of the provisional application, Ser. No. 61/035,158, that was filed on Mar. 10, 2008. FIELD OF THE INVENTION [0002] The present invention relates generally to a system and device for verifying an electronic voting record and method for the same, and in particular a system that utilizes a plurality of hand held devices that can verify the software and votes on an electronic voting record and method for the same. BACKGROUND OF THE INVENTION [0003] Many states have mandated the use of electronic voting machines. These machines are intended to replace the ubiquitous paper ballot, wherein a voter punches out a chad indicating their vote. The introduction of the electronic voting machine has been met with resistance and uncertainty, as there is a concern as to the validity, security, and safety of these machines. The overwhelming concern with using electronic voting machines is the validity of the results [0004] Many concerns arise based upon the perceived fear that the electronic voting machine might be altered or tampered with, causing an erroneous election result. These concerns are not entirely misplaced. Potential opportunities exist for fraud to occur during the use of electronic voting machines, such as 1) altering the electronic voting record; 2) compromising the voting software, creating an unintended result; and 3) altering the tabulation software, resulting in an erroneous final tabulation. [0005] The present invention is intended to belay these fears by providing a quick, non-intrusive system, device, and method to verify the software on an electronic voting machine and ensure accurate election results. BRIEF SUMMARY OF THE INVENTION [0006] A preferred embodiment of the present invention provides a software certification device that includes a voting machine monitor configured with a software system permitting a poll worker to verify software utilized during an election, a snapshot of a certified voting software stored on the voting machine monitor for comparison purposes, and at least one electronic voting machine coupled with the voting machine monitor. [0007] According to one preferred embodiment of the disclosed invention, a cradle recharges the software certification device. [0008] According to another preferred embodiment of the disclosed invention, a reset button is positioned on the voting machine monitor for resetting the software system contained thereon. [0009] According to yet another preferred embodiment of the disclosed invention, a vote recording and tabulation system for use with a plurality of electronic voting machines, including a first plurality of voting machine monitors configured with a software system permitting a poll worked to verify software utilized during an election, an independent tabulation system for accepting votes stored on the plurality of electronic voting machines, and a digital signature assigned to each vote cast by the voting machine monitor software running on the electronic voting machine, whereby each vote is downloaded to the independent tabulation system, wherein the independent tabulation system verifies the digital signature assigned to each vote and tabulates the final vote total. [0010] According to yet another preferred embodiment of the disclosed invention, a vote recording and tabulation system that includes a second plurality of voting machine monitors for scanning each first plurality of voting machine monitors to ensure the first plurality of voting machine monitors have not been tampered with. [0011] According to yet another preferred embodiment of the disclosed invention, a method of certifying an election that includes providing a voting machine monitor, creating a snapshot of the certified voting software on an electronic voting machine, downloading the snapshot to the voting machine monitor, attaching the voting machine monitor to an electronic voting machine, comparing the software on the electronic voting machine to the snapshot downloaded to the voting machine monitor, and displaying a result of the comparison of the software to the snapshot. [0012] According to yet another preferred embodiment of the disclosed invention, a method of certifying an election that includes signing each vote cast by a user on an electronic voting machine using a public key of the voting machine monitor. [0013] According to yet another preferred embodiment of the disclosed invention, a method of certifying an election that includes authenticating the voting machine monitor. [0014] According to yet another preferred embodiment of the disclosed invention, a method of certifying an election that includes exchanging a public and private key pair between the voting machine monitor and the electronic voting machine. [0015] According to yet another preferred embodiment of the disclosed invention, a method of certifying an election that includes communicating with the voting machine monitor via a serial communication protocol. [0016] According to yet another preferred embodiment of the disclosed invention, a method of certifying an election that includes downloading all votes cast on the electronic voting machine into an independent tabulation system, and verifying each votes' digital signature, and tabulating the final votes independent of the election machine vendor's tabulation. [0017] According to yet another preferred embodiment of the disclosed invention, a method of certifying an election, that includes connecting a voting machine monitor to an electronic voting machine that includes sending an identifying number by the voting machine monitor to the electronic voting machine, sending an additional identifying number by the voting machine monitor that is encrypted using a public key of the electronic voting machine monitor, decrypting the encrypted identifying number, sending an identifying number by the electronic voting machine encrypted using the voting machine monitor's public key, decrypting the encrypted identifying number, verification of the voting machine monitor and the electronic voting machine, transmission of the final keys necessary to complete the algorithm, and making a snapshot of the electronic voting machine software. [0018] According to yet another preferred embodiment of the disclosed invention, a method of certifying an election that includes seating the voting machine monitor in a cradle for recharging. [0019] According to yet another preferred embodiment of the disclosed invention, a method of certifying an election that includes depressing a rest button for resetting the software contained on the device. [0020] According to yet another preferred embodiment of the disclosed invention, a method of certifying an election that includes communicating via a serial communication protocol. [0021] According to yet another preferred embodiment of the disclosed invention, a method of certifying an election that includes providing a public private key pair to each voting machine monitor, providing a public private key pair to each electronic voting machine, and transmitting an identifying number to the electronic voting machine by the voting machine monitor. [0022] According to yet another preferred embodiment of the disclosed invention, a method of certifying an election that includes transmitting an identifying number to the voting machine monitor by the electronic voting machine. [0023] According to yet another preferred embodiment of the disclosed invention, a method of certifying an election that includes decrypting the identifying numbers using the private key of the electronic voting machine and voting machine monitor, respectively. [0024] According to yet another preferred embodiment of the disclosed invention, a method of certifying an election that includes verifying the voting machine monitor and electronic voting machine are authentic. [0025] According to yet another preferred embodiment of the disclosed invention, a method of certifying an election that includes transmitting the final keys necessary to complete the algorithm, thus enabling the voting machine monitor software to begin communicating and scanning the electronic voting machine software. BRIEF DESCRIPTION OF THE DRAWINGS [0026] The present invention is illustrated and described herein with reference to the various drawings, in which like reference numbers denote like method steps and/or system components, respectively, and in which: [0027] FIG. 1 is a perspective view of the device. [0028] FIG. 2 is another perspective view of the device with an optional cradle. [0029] FIG. 3 is a bottom view of the device. [0030] FIG. 4 is another perspective view of the device, exemplifying a not connected message. [0031] FIG. 5 is another perspective view of the device, exemplifying a connected message. [0032] FIG. 6 is another perspective view of the device, exemplifying a no differences found message. [0033] FIG. 7 is another perspective view of the device, exemplifying a warning message. DETAILED DESCRIPTION OF THE INVENTION [0034] Referring now specifically to the drawings, an exemplary device for verifying an electronic voting record is illustrated in FIG. 1 and is shown generally at reference numeral 10 . The device is commonly referred to as a voting machine monitor (VMM) that allows election officials to verify that an electronic voting machine's software and the actual vote recorded on the electronic voting machine have not been tampered with or altered. The VMM 10 can be of any shape and size, but in one exemplary embodiment, the VMM 10 is a handheld device that may be easily transported within the palm of an individual's hand. [0035] The VMM 10 may also utilize a cradle 12 for receiving the VMM 10 for recharging and storage. An example of a cradle 12 is illustrated in FIG. 2 . An electrical cord 14 is connected to the cradle 12 for supplying power and recharging the VMM 10 . Depending upon the configuration of the cord 14 , one end is inserted into either the female or male end of the cradle 12 , while the opposite end is inserted into an external power source, such as a standard electrical outlet. Alternatively, the electrical cord 14 may be inserted into the VMM 10 without the need for the cradle 12 . This arrangement allows the battery in the VMM 10 to be recharged without the use of the cradle 12 . [0036] In another exemplary embodiment, the cradle 12 may include a power pack or the like that can recharge the VMM 10 without the need for an electrical cord 14 to supply power to the cradle 12 . In this embodiment, the cradle 12 may contain rechargeable batteries to supply the appropriate power to the VMM 10 , wherein the rechargeable batteries may be recharged with the use of an electrical cord 14 . The electrical cord 14 may be inserted into the cradle 12 , and another end of the electrical cord 14 may be inserted into an electrical outlet, thus supplying the requisite power to recharge the batteries. [0037] As illustrated in FIG. 3 , the VMM 10 contains a recessed reset button 16 . The reset button is recessed within the body of the VMM 10 for preventing the accidental resetting of the device. The reset button is recessed within a channel bored into the body of the VMM 10 . The channel has a diameter substantially the same size as the head of a safety pin or a ball point pen, allowing the user to insert these articles into the channel to depress the reset button. When the reset button is depressed, the software on the VMM 10 is restarted. [0038] The electronic voting machine described herein may be a direct-recording electronic (DRE) voting machine. Since the DRE is the most prominent electronic voting machine in use today, DRE is used herein out to describe the electronic voting machine. However, the term DRE is not mean to depart from or limit the intent and scope of the disclosed invention. The DRE records votes utilizing a ballet display provided by mechanical or electro-optical components. The components are activated by the user using a touch screen to make the appropriate ballot selection. The DRE stores each vote, and produces a tabulation at the end of the election of the voting data stored therein. The DRE may also print the tabulation as a hard copy. [0039] Prior to the election, it is important to certify that the software on each DRE is the actual and intended certified software, which has been approved by the state voting authority. From a security standpoint, it is extremely important to ensure that the software on each machine is certified, resulting in the machine publishing the correct ballot and tabulating an accurate number of votes cast for a particular candidate. Most states have a mandatory procedure for certifying the software contained on the DRE, allowing the software to be certified by the state itself or an independent testing authority. [0040] The VMM 10 is designed for connection to a typical voting machine for verifying the software operating on the voting machine is certified. The VMM 10 is also designed to record the votes that have been cast on the voting machine to ensure the accuracy of the votes at any time within the span of an election. The VMM 10 may be connected to the voting machine before voting actually begins, during the time period when voting is occurring, after all voting has been completed, or combinations thereof. The VMM 10 is designed for use at any stage in the voting process to verify the software on the voting machine is certified, and to ensure the votes cast by a voter are legitimate, resulting in accurate final tabulations. [0041] The VMM 10 is used to verify that certified software is being utilized during the election. The VMM 10 is wholly separate from the DRE, and is only externally connected to the DRE at the desire of the election worker. The prior art devices utilize an integral verification system, which is inferior to the disclosed invention. The disclosed invention provides for better security because of the physical separation of the VMM and DRE, resulting in the physical separation of specified duties. [0042] A central database and recording system may be utilized to organize and control a plurality of the VMMs during an election. The central database tracks each VMM 10 used during the election, and may track each individual DRE. The central database includes an independent tabulation system (ITS) to accept votes stored on the plurality of DREs, enabling the votes to be independently counted and recorded by the recording system. In one exemplary embodiment, the information stored on the DRE, including the voting races, are loaded and stored on the ITS. [0043] Prior to using the VMM 10 , an initialization process is commenced. During the initialization process, each DRE is registered with the VMM's central software database, and each VMM 10 is registered with the central software database as well. Public key cryptography or asymmetric cryptography is utilized to ensure confidentiality. Once the state or an independent testing authority has certified the software on the DRE and possibly the software on the VMM 10 , the central system provides a RSA public private key pair to each VMM 10 and a public private key pair to each DRE. The purpose of these keys is to authenticate the DRE and the VMM 10 when the VMM 10 is connected to the DRE during the election process to ensure confidentiality. The DRE receives a DRE private key and a VMM public key, while the VMM 10 receives a VMM private key and a DRE public key. [0044] The keys are utilized to authenticate the DRE and VMM 10 when a connection is made between them. The private key is kept confidential, while the public key may be widely distributed. The keys are related mathematically, but the private key cannot be derived from the public key, resulting in a message encrypted with the public key only being decrypted by a corresponding private key. The DRE also utilizes the VMM public key to record a VMM signature for each vote as it is cast and recorded. The vote may be verified with the public key, proving the authenticity of the signed vote and that the vote has not been tampered with. [0045] Once the DRE software has been certified, a digital snapshot of the certified software is created and downloaded to the VMM central system. The digital snapshot is then loaded onto each VMM 10 for comparing the software on the DRE during the election process to ensure the previously certified software is running on the DRE. [0046] The DRE contains a read only software program that communicates with the VMM 10 using a serial communication protocol. The DRE does not know the full algorithm necessary to enable the VMM 10 to scan the DRE software for making a snapshot of the software. The missing algorithm keys to complete the scan process are not transmitted until after the devices are connected, wherein the software authenticates the legitimacy of the VMM 10 , and the VMM 10 authenticates the legitimacy of the DRE. The DRE contains the VMM 10 software enabling a snapshot of the DRE software to be recorded, and the signing of each vote cast by a voter by the VMM 10 for increasing security. [0047] During the election process, a voter casts a ballot for a particular candidate. When the vote is cast, the vote is signed using the VMM's public key and stored on the DRE. Alternatively, the vote may be signed with the VMM's private key. While the DRE software is static and will not change, the VMM's “read only” software program is active, waiting for a connection to be made by a VMM 10 . Obviously, the most practical time to connect the VMM 10 to the DRE is when a voter is not actively using the voting machine. For connection, the VMM 10 is connected to the DRE by way of a connection cable or the like. The connection cable may be any suitable method of serial communication, including, but not limited to, DB9, DB25, centronics parallel, USB, PCMCIA, express card, smartcard, or any other similar method of communicating instructions from one device to another. The VMM 10 will produce a message to the user indicating whether or not the VMM 10 is connected to the DRE. For example, when a VMM 10 is not properly connected to the DRE a warning message is displayed, as illustrated in FIG. 4 , but when a proper connection is accomplished, an indication message is displayed, as illustrated in FIG. 5 . [0048] Once connected, the VMM 10 initially attempts to contact the DRE. If this attempt is successful, meaning there is an active connection between the VMM 10 and DRE, the VMM 10 sends an identifying number that is received by the DRE. In return, the DRE sends its identifying number to the VMM 10 . The VMM 10 then transmits another identifying number that is encrypted using the DRE public key, which the DRE decrypts using its private key to verify. Thereafter, the DRE transmits an identifying number that is encrypted using the VMM public key, which the VMM 10 decrypts using its private key to verify. The identifying numbers allow the VMM 10 and DRE to verify and authenticate the other device. When the VMM 10 and DRE have successfully verified and authenticated each other, substantive communication may begin therebetween. [0049] The VMM 10 transmits the last keys that are necessary to complete the algorithm, thus enabling the VMM software on the DRE to begin communicating and scanning the DRE software and capturing a digital snapshot of the software. When the devices are connected, the last keys of the algorithm are sent, thus initiating the scanning process. This arrangement prevents a “false positive” response that could occur if the VMM software on the DRE was replaced. Once the DRE software has been scanned and a complete digital snapshot has been created, the snapshot is encrypted and transmitted to the VMM 10 , where the snapshot is decrypted. The VMM 10 compares the newly created snapshot to the certified snapshot that was downloaded to the VMM 10 before the election process was commenced by the state or independent testing authority. After the snapshots are compared, the results are recorded on the VMM 10 . [0050] As mentioned above, the VMM's public key signs each vote as it is cast by a voter. The VMM software running on the DRE would utilize the keys to compare the digital signature of each vote to ensure the votes have not been altered subsequent to the vote being cast. The VMM software simply scans for the digital signature that was signed by the public key, and confirms that the digital signature was the signature placed at the time the vote was cast. The results are transmitted back to the VMM 10 . [0051] The VMM 10 displays the results of the scanning process in an easy to read format on an LCD screen or the like. The disclosed invention makes the verification process easy to complete by an election poll worker. As illustrated in FIGS. 6 and 7 , the displayed results are straight forward and easily understandable by a poll worker. As shown in FIG. 6 , if the snapshots compared by the VMM 10 are identical, the VMM 10 displays a result of “No Differences Found” or the like. On the other hand, if the snapshots are not identical, a result) as shown in FIG. 7 , is displayed that could consist of a red warning box or the like. If a display as in FIG. 7 is displayed, indicating a problem with the DRE, the voting machine is immediately removed from the election process. [0052] After the polls close and the election is over, each DRE, or the DRE storage device (e.g PCMCIA cards) are transported to an offsite location for vote tabulation. The votes stored on each DRE are downloaded into the election machine vendor's tabulation software system. These votes would also be downloaded into the disclosed invention's ITS. The ITS again verifies each vote's digital signature, and after each signature is verified, the final votes are tabulated. The ITS has the ability to create a set of reports that contain the final vote tabulation, allowing these reports to be compared to the vendor's voting reports for comparison. If a discrepancy occurs, the system will allow for a follow-up electronic review and reconciliation. [0053] To ensure the accuracy of the results, the DRE would be scanned a final time by a set of VMM 10 that have been stored at a central location, away from the various polling locations. The centrally stored VMMs would scan the various DREs as mentioned above. After being scanned this final time, the ITS generates a report of scanning process before the final results of the election may be certified. [0054] Although the present invention has been illustrated and described herein with reference to preferred embodiments and specific examples thereof, it will be readily apparent to those of ordinary skill in the art that other embodiments and examples may perform similar functions and/or achieve like results. All such equivalent embodiments and examples are within the spirit and scope of the present invention and are intended to be covered by the following claims.

The present invention provides methods and systems for a vote recording and tabulation system for use with a plurality of electronic voting machines, including a first plurality of voting machine monitors configured with a software system permitting a poll worked to verify software utilized during an election, an independent tabulation system for accepting votes stored on the plurality of electronic voting machines, and a digital signature assigned to each vote cast by the voting machine monitor software running on the electronic voting machine, whereby each vote is downloaded to the independent tabulation system, wherein the independent tabulation system verifies the digital signature assigned to each vote and tabulates the final vote total.

BACKGROUND OF THE INVENTION The present invention generally relates to a convergence apparatus and a convergence yoke to be used for the convergence apparatus. The present invention particularly relates to a convergence apparatus in which it is possible to prevent an electron beam spot from deteriorating at the time of convergence correction to thereby provide a good focusing performance, and a convergence yoke to be used for such a convergence apparatus. In a color display of a projection type color television receiver, a plurality of single-electron-gun type cathode-ray tubes are used and monochromatic images of red (R), green (G), and blue (B) of the respective cathode-ray tubes are projected on a projection screen through an optical system composed of a reflection mirror, a lens, etc., so as to form a color picture on the screen. At this time, in each cathode-ray tube, an electron beam is deflected by a substantially even magnetic field type deflection yoke and image carrying light of the cathode-ray tube is projected on a projection screen 101 (FIGS. 1 and 2) through an optical system, so that a pincushion distortion 102 as shown in FIG. 1 or a trapezoidal or keystone distortion 103, 103' as shown in FIG. 2 appears on the projection screen 101. In order to correct such a distortion, conventionally, a convergence apparatus has been provided in each cathode-ray tube. Such a convergence apparatus is constituted by a convergence yoke and a convergence circuit, the convergence yoke being provided in the electron-gun side rear of a deflection yoke. The convergence yoke has a core composed of a ring-like portion and four or two-pairs of rectangular core protrusions, each pair being located on the horizontal and vertical axes respectively and inward projected from the ring-like portion. The convergence circuit makes a convergence correction current i c flow into coils wound on the core protrusions in synchronism with a horizontal deflection current i H or a vertical deflection current i v as shown in FIG. 3 so as to generate a horizontal bipolar magnetic field between the one pair of core protrusions (magnetic poles) located on the horizontal axis at positions opposite to each other and a vertical bipolar magnetic field between the other pair of core protrusions (magnetic poles) located on the vertical axis at positions opposite to each other, so that vertical and horizontal deflection forces are exerted on the electron beam to correct the above-mentioned pincushion distortion 102 or the keystone distortion 103, 103' . Alternatively, as is shown in FIG. 6 of Japanese Utility Model Publication No. 58-32378, there has been proposed another example of a core of a convergence yoke in which an 8-pole core having two pairs of a first set of four core protrusions located on the horizontal and vertical axes respectively and a second set of four core protrusions positioned at circumferentially intermediate angular positions between adjacent ones of the first set of four core protrusions, and in which an AC current is made to flow in coils wound on the first set of four core protrusions to perform dynamic convergence correction (that is, correction of the foregoing pincushion distortion 102 or the keystone distortion 103, 103') and a DC current is made to flow in coils wound on the second set of four core protrusions so as to perform static correction. In the prior art, as described above, there have been two examples of a convergence yoke of a convergence apparatus, one example being a case ○1 in which horizontal and vertical bipolar magnetic fields are generated by two pairs of core protrusions positioned on the horizontal and vertical axes respectively, the other example being a case ○2 in which horizontal and vertical bipolar magnetic fields are generated by four core protrusions positioned at circumferentially intermediate angular positions between the horizontal and vertical axes (that is, positions angularly deviated, for example, by 45° or the like from the horizontal and vertical axes). The respective shapes of the horizontal and vertical bipolar magnetic fields in the foregoing cases, that is, the shapes of magnetic fields acting on an electron beam, will be described hereunder. First, the former case ○1 will be described by using FIG. 4. FIG. 4 is a sectional view showing a example of a convergence yoke in a conventional convergence apparatus. In FIG. 4, reference numerals 6 and 7 designate vertical and horizontal bipolar magnetic fields (N, S) respectively; 15b and 15b' designate horizontal deflection coils; 16a and 16a' designate vertical deflection coils; 17, 17' and 18, 18' designate input terminals; 50 designates a core; and a, a' and b, b' designate core protrusions. As is apparent from FIG. 4, in the case where a bipolar magnetic field in the horizontal direction (x-direction) is generated by the pair of core protrusions a and a' provided on the horizontal axes and another bipolar magnetic field in the vertical direction (y-direction) is generated by the pair of core protrusions b and b' provided on the horizontal axes, the qualitative shape of each of the resultant bipolar magnetic fields shows a section of a glass tube through which the electron beam passes. Since the convergence yoke has a structure symmetrical with respect to the x-axis as well as the y-axis as shown in FIG. 4, description will be made hereunder only about the vertical bipolar magnetic field (the horizontal convergence correcting magnetic field B y ). The horizontal convergence correcting magnetic field B y is expressed by the following expression (1). B.sub.y =B.sub.0 +B.sub.2 ·x.sub.2 ]10.sup.-4 T]. . . (1) where x represents an amount of deviation in the horizontal direction (x-direction) from a reference, that is, a tube axis (an axis perpendicular to the paper plane and passing through the intersection of the horizontal and vertical axes in FIG. 4), B 0 represents the magnetic flux density on the tube axis, and B 2 represents a value expressed as follows. ##EQU1## where B(x) represents the magnetic flux density at a position deviated in the horizontal direction by x from the tube axis, and B(-x) represents the magnetic flux density at a position deviated in the horizontal direction by -x from the tube axis. Although actual magnetic flux density contains higher order components of even number degree four or more (x 4 , x 6 , x 8 , . . . ) with respect to x, those components are omitted in the above expression (1). In the above expression (1), B 2 represents an uneven magnetic field component of the vertical bipolar magnetic field 6. FIG. 5 is an explanatory diagram showing, along a tube axis, a distribution of an uneven magnetic field component of a bipolar magnetic field generated in the conventional convergence yoke of FIG. 4. In FIG. 5, the abscissa represents the coordinate Z in the direction of tube axis (in the direction perpendicular to the paper plane in FIG. 4), and the axis of ordinates represents the value of B 2 /B 0max which is obtained by normalizing the uneven magnetic field component B 2 with the maximum value B 0max of the magnetic flux density B 0 on the tube axis. The reference numeral 13 represents the distribution curve of the value of B 2 /B 0max , and 14 represents the position, on the tube axis, of the core 50 of the convergence yoke in FIG. 4. In this case, it is considered that the distribution curve of the value of B 2 /B 0max may take the following three states (a), (b) and (c). (a) The case where both the B 2 and B 0 take positive values: B 2 >0 and B 0 >0 so that B 2 /B 0max takes a value in the positive region in FIG. 5 and therefore B 2 /B 0 >0 and B 0 <B(x). Accordingly, the magnetic field becomes a pincushion magnetic field. (b) The case where B 2 takes a negative value, while B 0 takes a positive value: B 2 <0 and B 0 >0 so that B 2 /B 0max takes a value in the negative region in FIG. 5 and therefore B 2 /B 0 <0 and B 0 >B(x). Accordingly, the magnetic field becomes a barrel magnetic field. (c) The case where B 2 becomes zero: B 2 =0 and B 2 /B 0 =0, so that B 2 /B 0max takes a value on the abscissa in FIG. 5 and therefore the magnetic field becomes an even one. As seen from FIG. 5, in the case where horizontal and vertical bipolar magnetic fields are generated by two pairs of core protrusions positioned on the horizontal and vertical axes respectively, the magnetic fields become like a barrel over the whole region in the direction of the tube axis and the barrel shape becomes most remarkable at a central position A of the convergence yoke. FIG. 6 is a partly broken side view of a cathode-ray tube and peripheral devices and FIG. 7 is an explanatory diagram showing a state in which a shape of an electron beam spot is distorted by a barrel magnetic field component of a bipolar magnetic field generated in the convergence yoke of FIG. 4. In FIG. 6, the reference numeral 32 represents a cathode-ray tube, 33 represents a fluorescent screen, 34 represents a horizontal deflection coil, 35 represents a vertical deflection coil, 36 represents a deflection yoke core, 37 represents a deflection yoke, 38 represents a deflection circuit, 39 represents a convergence yoke, 40 represents a convergence circuit, 41 represents a centering magnet, 42 represents a cathode-ray tube wall, and 43 represents an electron gun. As shown in FIG. 6, the convergence yoke 39 is positioned in the electron-gun side rear of the deflection yoke 37 so that a bipolar magnetic field in the vertical (horizontal) direction is exerted on an electron beam. If such a barrel magnetic field as described above is exerted on an electron beam in this configuration, the shape of a spot 29 of the electron beam is triangularly distorted as indicated with a reference numeral 30 in FIG. 7 to thereby deteriorate the focusing performance. That is, the reference numerals 29 and 30 designate the shape of the spot of an electron beam before and after the electron beam enters the region of the convergence yoke, respectively. Next, referring to FIG. 8, description will be made about the latter case ○ 2 in which horizontal and vertical bipolar magnetic fields are generated by four core protrusions positioned at circumferentially intermediate angular positions between the horizontal and vertical axes (that is, positions angularly deviated, for example, by 45° or the like from the horizontal and vertical axes). FIG. 8 is a sectional view showing another example of a convergence yoke in a conventional convergence apparatus. In FIG. 8, the reference numerals 24a, 24a' , 24b and 24b' represent horizontal deflection coils; 25, 25' , 26 and 26' input terminals; 27a, 27a', 27b and 27b' represent vertical deflection coils; and 51 represents a core. As will be apparent from FIG. 8, in the case where horizontal and vertical bipolar magnetic fields 7 and 6 are generated by four core protrusions a, a', b and b' located at positions angularly deviated by 45° from the horizontal and vertical axes respectively, that is, in the case where each magnetic pole is constituted by adjacent two of the core protrusions which are positioned on the both sides of and deviated from each magnetic field symmetry axis and each bipolar magnetic field is generated between each pair of opposite magnetic poles (for example, the vertical bipolar magnetic field 6 is generated between one magnetic pole constituted by the two adjacent core protrusions a and b' located on the both sides of the vertical axis which is the magnetic field symmetry axis and the other magnetic pole constituted by the two adjacent core protrusions a' and b located on the both sides of the same vertical axis), the qualitative shape of each of the bipolar magnetic fields is like a pincushion. FIG. 9 is an explanatory diagram showing, along a tube axis, a distribution of an uneven magnetic field component of a bipolar magnetic field generated in the conventional convergence yoke of FIG. 8. As will be apparent in FIG. 9, the B 2 /B 0max distribution curve 13 exists in the positive region so that the magnetic field is a pincushion magnetic field in the certain region from the center of the core 51 in the direction of the tube axis. The action of the convergence yoke forming such a pincushion magnetic field on an electron beam spot distorts the shape of the electron beam spot from a round one into a triangular one, on the contrary to the case of the foregoing barrel magnetic field, as shown in FIG. 10, resulting in deterioration in focusing performance. SUMMARY OF THE INVENTION It is therefore an object of the present invention to solve the foregoing problems in the prior art. It is another object of the present invention to provide a convergence apparatus in which deterioration generated in electron beam spot at the time of convergence correction can be reduced so that the focusing performance can be improved. It is a further object of the present invention to provide a convergence apparatus in which the deflection sensibility of the convergence yoke can be improved. In order to attain the above objects, in the convergence apparatus according to an aspect of the present invention, each of two magnetic poles for generating a bipolar magnetic field is constituted by a first core protrusion located on a magnetic field symmetry axis (a horizontal or vertical axis) and at least one pair of second core protrusions located on positions equiangularly and symmetrically deviated by an angle θ from the magnetic field symmetry axis, and the value of ratio of an ampere turn of the coil wound on each of the second core protrusions to an ampere turn of the coil wound on the first core protrusion is selected to cos θ. The term of "ampere turn" is defined as a product N·I of the number of turns N of a coil and a current I passing through the coil. In the convergence apparatus according to another aspect of the present invention, each of two magnetic poles for generating a bipolar magnetic field is constituted by at least one pair of ones of a plurality of core protrusions located on positions equiangularly and symmetrically deviated from a horizontal or vertical axis, and in the case where a first pair of the core protrusions constituting each of the magnetic poles are located at position equiangularly deviated by an angle θ 1 from the horizontal or vertical axis and the other or a second pair of the core protrusions constituting each of the magnetic poles are located positions equiangularly deviated by an angle θ from the horizontal or vertical axis, the ratio of an ampere turn of the coil wound on the second core protrusion to an ampere turn of the coil wound on the first core protrusion is selected to be cos θ/cos θ 1 . In the convergence apparatus according to a further aspect of the present invention, each of two magnetic poles for generating a bipolar magnetic field is constituted by only a pair of ones of a plurality of core protrusions located on positions equiangularly and symmetrically deviated by 30° from a magnetic field symmetry axis and the ampere turns of the respective coils wound on the pair of core protrusions are made equal to each other. In the convergence apparatus according to a still further aspect of the present invention, a first magnetic auxiliary plate and a second magnetic auxiliary plate are provided on a first core protrusion constituting each of a first pair of magnetic poles and on a second core protrusion constituting each of a second pair of magnetic poles respectively. Each of the first and second magnetic auxiliary plates has a fork end projected along an axis perpendicular to a horizontal axis as well as a vertical axis. The first and second magnetic auxiliary plates have respective widths existing within an angular range symmetrically deviated by 45° from the horizontal axis and within an angular range symmetrically deviated by 45° from the vertical axis respectively. Each of the first and second magnetic auxiliary plates has a substantially Y-shaped and axisymmetrical form. The first magnetic auxiliary plate is made different from the second magnetic auxiliary plate in projecting direction of their fork end portions. In the foregoing case where each of two magnetic poles for generating a bipolar magnetic field is constituted by a first core protrusion located on a magnetic field symmetry axis (a horizontal or vertical axis) and at least one pair of second core protrusions located on positions equiangularly and symmetrically deviated by an angle θ from the magnetic field symmetry axis, the barrel magnetic field component included in the magnetic field generated by means of the first core protrusions and the pincushion magnetic field component included in the magnetic field generated by means of the second core protrusions are canceled with each other so that the resultant bipolar magnetic field generated synthetically becomes substantially even. In the foregoing case where each of two magnetic poles for generating a bipolar magnetic field is constituted by only a pair of ones of a plurality of core protrusions located on positions equiangularly and symmetrically deviated by 30° from a magnetic field symmetry axis, the second order component of the generated magnetic field is substantially zero so that the bipolar magnetic field becomes substantially even. In the foregoing case where a magnetic auxiliary plate having a fork end projected along an axis perpendicular to a horizontal axis as well as a vertical axis, having a width existing within an angular range symmetrically deviated by 45° from a magnetic field symmetry axis, and having a substantially Y-shaped and axisymmetrical form is provided on a core protrusion constituting each of a pair of magnetic poles for generating a bipolar magnetic field, a part of the magnetic field distributed in the barrel-like shape from the core protrusion constituting the one of the two magnetic poles to the other passes through the magnetic auxiliary plate so as to increase the amount of the magnetic field passing through the magnetic paths at peripheral portions to make the second order component of the magnetic field have a tendency to become pincushion like, so that the resultant bipolar magnetic field generated synthetically is corrected to have a substantially even shape. In this case, further, the first and second magnetic auxiliary plates related to the bipolar magnetic fields in the direction of the horizontal and vertical axes respectively are made different from each other in projecting direction of their fork end portions, no ineffective magnetic paths are made by those first and second magnetic auxiliary plates so that the generated magnetic field acts on the electron beam effectively. BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the present invention will now be described taken in connection with the accompanying drawings, in which: FIGS. 1 and 2 are diagrams showing distortion for explanation of the present invention; FIG. 3 is a waveform diagram of showing one example of a deflection current and a convergence correction current for explanation of the present invention; FIG. 4 is a sectional view showing an example of a convergence yoke in a conventional convergence apparatus; FIG. 5 is an explanatory diagram showing, along an tube axis, a distribution of an uneven magnetic field component of a bipolar magnetic field generated in the conventional convergence yoke of FIG. 4; FIG. 6 is a partly broken side view of a cathode-ray tube and peripheral devices; FIG. 7 is an explanatory diagram showing a state in which a shape of an electron beam spot is distorted by a barrel magnetic field component of a bipolar magnetic field generated in the convergence yoke of FIG. 4; FIG. 8 is a sectional view showing another example of a convergence yoke in a conventional convergence apparatus; FIG. 9 is an explanatory diagram showing, along an tube axis, a distribution of an uneven magnetic field component of a bipolar magnetic field generated in the conventional convergence yoke of FIG. 8; FIG. 10 is an explanatory diagram showing a state in which a shape of an electron beam spot is distorted by a pincushion magnetic field component of a bipolar magnetic field generated in the convergence yoke of FIG. 8; FIG. 11 is a sectional view showing a first embodiment of a convergence yoke of a convergence apparatus according to the present invention; FIG. 12 is an explanatory diagram showing, along an tube axis, magnetic flux density and uneven magnetic field component distribution of a bipolar magnetic field generated in the convergence yoke of FIG. 11; FIG. 13 is a sectional view showing a second embodiment of a convergence yoke of a convergence apparatus according to the present invention; FIG. 14 is a sectional view showing a third embodiment of a convergence yoke of a convergence apparatus according to the present invention; FIG. 15 is a sectional view showing a fourth embodiment of a convergence yoke of a convergence apparatus according to the present invention; FIG. 16 is a side view in the direction of XVI--XVI in FIG. 15; FIG. 17 is a plan view of the magnetic auxiliary plate shown in FIG. 15; and FIG. 18 is an explanatory view showing comparison of the distribution, along an tube axis, of an uneven magnetic field component of a bipolar magnetic field generated in the convergence yoke of FIG. 14 between the cases where the magnetic auxiliary plates are provided and not provided. DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 11 is a sectional view showing a first embodiment of a convergence yoke of a convergence apparatus according to the present invention. In FIG. 11, the parts the same as or equivalent to those in FIGS. 4 and 8 are referenced correspondingly. In FIG. 11, reference numerals 1a, 1a', 1b, 1b', 1c, 1c' designate vertical deflection coils; 2b, 2b', 2c, 2c' designate horizontal deflection coils; 3, 3', 4, 4' designate input terminals; 52 designates a core; and a, a', b, b', c, c' designate core protrusions. As shown in FIG. 11, the core 52 has a ring-like portion and 6 rectangular core protrusions a, a', b, b', c, c' which are provided equidistantly at circumferentially angular intervals of 60° on the inner circumference of the ring-like portion so as to inward project towards the center axis of the ring-like core 52. The convergence yoke shown in FIG. 11 generates horizontal and vertical bipolar magnetic fields 7 and 6 crossing each other. Specifically, in order to generate the vertical bipolar magnetic field 6, the core protrusions b and c are disposed in pair in positions symmetrical with respect to the vertical axis and circumferentially separated by 30° from each other so as to form one magnetic pole and the core protrusions b' and c' are disposed in pair in positions symmetrical with respect to the vertical axis and circumferentially separated by 30° from each other so as to form the other magnetic pole. The coils 2b, 2b', 2c and 2c' are wound on the core protrusions b, c, b' and c' respectively so that the magnetic pole formed by the core protrusions b and c and the core protrusions b' and c' are reversed in polarity when a convergence correction current is made to flow across the input terminals 3 and 3'. In the configuration, the bipolar magnetic field generated the two magnetic poles in the vertical direction becomes substantially even. This is because the respective core protrusions constituting the magnetic poles are disposed at positions respectively deviated by 30° from the vertical axis of symmetry. The barrel magnetic field component becomes stronger as the angle θ is made smaller than 30°, while the pincushion magnetic field component becomes stronger as the angle θ is made larger than 30°. Accordingly, it is ideal to select the angle θ to be 30°. On the other hand, the magnetic poles constituting the horizontal bipolar magnetic field 7 can be arranged similarly to the case of the vertical bipolar magnetic field 6. In this case, however, the angular distance between the adjacent core protrusions constituting the horizontal and vertical magnetic fields respectively is so small, only 30°, that it becomes necessary to reduce the respective width of the core protrusions, the respective thickness of the coils and the respective width of the coil bobbins thereby causing a difficulty in practical use. Accordingly, one magnetic pole is formed of the three core protrusions, that is the core protrusion a disposed on the horizontal axis of symmetry and the core protrusions b and b' disposed on the opposite sides of the core protrusion a and each separated from the horizontal axis by 60°. That is, the core protrusions b and b' disposed on the opposite sides of the core protrusion a are used commonly to constitute the horizontal magnetic field as well as the vertical magnetic field. The ratio of the number of turns of winding Na of the coil 1a wound on the core protrusion a to the number of turns of winding Nb of each of the coils 1b and 1b' respectively wound on the core protrusions b and b' is selected to be as shown in the following expression (3). Nb/Na=cos 60°/cos 0°=1/2. . . (3) Similar to the above case, with respect to the core protrusions a', c and c' disposed in opposition to the core protrusions a, b and b' the number of turns of winding Nc of each of the coils 1c and 1c' respectively wound on the core protrusions c and c' disposed on the opposite sides of the core protrusion a' to the ratio of the number of turns of winding Na of the coil 1a' wound on the core protrusion a' is selected to be as shown in the following expression (4). Nc/Na=cos 60°/cos 0°=1/2. . . (b 4) Then, as there occurs ampere turn (magnetomotive force) in proportion to magnetic path length, the magnetic field of the same size occurs. The coils 1a, 1b and b' are connected to each other while the coils 1a', 1c and 1c' are connected to each other so that the magnetic pole constituted by the core protrusions a, b and b' and magnetic pole constituted by the core protrusions a', c and c' are reversed in polarity to each other. In this configuration, similarly to the case of the vertical bipolar magnetic field 6, the horizontal bipolar magnetic field 7 is a substantially even magnetic field. This is because the ratio of the number of turns of the winding of each of the coils 1b and 1b' wound on the core protrusions b and b' to the number of turns of the winding of the coil 1a wound on the core protrusion a is selected to be 178 , and the number of turns of winding of the coils 1c and 1c' wound on each of the core protrusions c and c' to the number of turns of winding of the coil 1a' wound on the core protrusion a' is also selected to be 1/2. If the number of turns of winding of each of the coils 1b and 1b' or each of the coils 1c and 1c' is increased, the pincushion component becomes large, while if that number of turns is decreased, the barrel component becomes large. FIG. 12 is an explanatory diagram showing, along an tube axis, magnetic field density and uneven magnetic field component distribution of a bipolar magnetic field generated in the convergence yoke of FIG. 11. In FIG. 12, the abscissa represents the coordinate Z in the direction of tube axis (in the direction perpendicular to the paper plane in FIG. 11), the axis of ordinates at the left side represents the magnetic flux density B 0 [10 -4 T]on the tube axis, and the axis of ordinates at the right side represents the value of B 2 /B 0max [10 -4 /mm 2 ]which is obtained by normalizing the uneven magnetic field component B 2 with the maximum value B 0max of the magnetic flux density B 0 on the tube axis. The reference numeral 12 represents the distribution curve of the magnetic flux density B 0 , 13 represents the distribution curve of B 2 /B 0max , and 14 represents the position, on the tube axis, of the core 52 of the convergence yoke. As seen in FIG. 12, the value of B 0 is maximum at the center of the convergence yoke, and becomes smaller as the position comes away from the center toward the electron gun side or toward the fluorescent screen. On the other hand, the distribution curve of B 2 B 0max shows a weak pincushion magnetic field within the convergence yoke, while shows a weak barrel magnetic field before and after the convergence yoke. Accordingly, the magnetic field distribution is substantially even in general. In this first embodiment, as described above, the vertical bipolar magnetic field is generated by the four core protrusions b, c, b', and c', that is, a pair of core protrusions b and c which are symmetrical with each other with respect to the vertical magnetic field symmetrical axis (vertical axis) and another pair of core protrusions b' and c' which are symmetrical with each other with respect to the same vertical axis, while the horizontal bipolar magnetic field is generated by the six core protursions a, b, b', a', c and c', that is, a set of the three core protusions a located on the horizontal magnetic field symmetrical axis (horizontal axis) and b and b' which are symmetrical with each other with respect to the same horizontal axis and another set of the three core protrusions a' located on the same horizontal axis and c and c' which are symmetrical with each other with respect to the same horizontal axis. Alternatively, however, the whole of the convergence yoke may be rotated by 90° so as to reverse the arrangements for the horizontal and vertical magnetic fields to each other. FIG. 13 illustrates a second embodiment of a convergence yoke of a convergence apparatus according to the present invention, in which the whole of the convergence yoke in the first embodiment is rotated by 90° so as to reverse the arrangements for the horizontal and vertical magnetic fields to each other. Being the same as that described with respect to FIG. 12, the operation of the second embodiment of FIG. 13 is not described here. FIG. 14 is a sectional view showing a third embodiment of a convergence yoke of a convergence apparatus according to the present invention. In FIG. 14, reference numerals 8, 8', 9, 9' designate input terminals; 10a, 10a', 10b, 10b', 10c, 10c' designate vertical deflection coils; 11b, 11b', 11c, 11c', 11d, 11d' designate horizontal deflection coils; 53 designates a core; and a, a', b, b', c, c', d, d' designate core protrusions. As shown in FIG. 14, the core 53 has a ring-like portion and eight core protrusions a, b, c, d, a', b', c', d' which are provided equidistantly at circumferentially angular intervals of 45° on the inner circumference of the ring-like portion so as to inward project towards the center axis of the ring-like core 53. Of those eight core protrusions a, b, c, d, a', b', c', d', the pair of core protrusions a and a' are located on the horizontal magnetic field symmetrical axis (horizontal axis), while the pair of core protrusions d and d' are located on the vertical magnetic field symmetrical axis (vertical axis). The opposite magnetic poles of the horizontal bipolar magnetic field 7 are constituted by the three core protrusions a, b and b' and the three core protrusions a', c and c' respectively, while the opposite magnetic poles of the vertical bipolar magnetic field 6 are constituted by the three core protrusions b, d and c and the three core protrusions b', d' and c'. The core protrusions b and c are arranged to be symmetrical with the core protrusions b' and c' respectively at 45° with respect to the horizontal magnetic field symmetrical axis (horizontal axis), while the core protrusions b and b' are arranged to be symmetrical with the core protrusions c and c' respectively at 45° with respect to the vertical magnetic field symmetrical axis (vertical axis). That is, the four core protrusions b, b', c and c' are commonly used to generate the horizontal and vertical magnetic fields. The number of the core protrusions and the connection of coils for constituting each magnetic pole in this third embodiment are the same as those for constituting each magnetic pole for generation of the horizontal bipolar magnetic field 7 in the above first embodiment. However, because the core protrusions b and b' and the core protrusions c and c' are located at the opposite sides of the core protrusions a and a' respectively at smaller angles of 45° in comparison with the first embodiment, the ratio of the number of turns of winding Nb of each of the coils wound on the core protrusions b, b', c and c' to the number of turns of winding Na of each of the coils wound on the core protrusions a, a', d and d' is selected to be as shown in the following expression (5). Nb/Na=cos 45°/cos 0°=1/√2 . . . (5) In the thus arranged magnetic pole configuration, each of the generated horizontal and vertical bipolar magnetic fields 7 and 6 is substantially even. In the third embodiment, the magnetic flux density on the tube axis and the uneven magnetic field component of the generated bipolar magnetic fields are the same as those in the embodiment of FIG. 12. In the first, second and third embodiments, as described above, each of the horizontal and vertical bipolar magnetic fields can be made substantially even, so that such distortion in shape of the electron beam spot as shown in FIG. 7 or 10 can be reduced to thereby improve the focusing performance. In the foregoing first, second and third embodiments, as means for generating substantially even bipolar magnetic fields, the relation between the core protrusion attaching positions and the number of turns of winding of the coils is set as follows. That is, in the case where two core protrusions are used for each magnetic pole, the attaching positions of the two core protrusions are set at the opposite sides of the axis of symmetry of the magnetic field so as to be deviated by 30° from the axis of symmetry and the numbers of turns of winding on the respective core protrusions are made equal to each other. In the case where three core protrusions are used for each magnetic pole, the attaching positions of the respective core protrusions are set so that one of the three core protrusions is located at a position on the axis of symmetry of the magnetic field and the other two core protursions are located at positions equiangularly symmetrically deviated from the axis of symmetry of the magnetic field at the angle of θ, and the value of ratio N of the number of turns of each of the coils wound on the two core protrusions on the positions symmetrical with respect to the axis of symmetry of the magnetic field to the number of turns of the coil wound on the core protrusion on the axis of symmetry is selected to be N=cos θ . . . (6) Although the case where both the horizontal and vertical bipolar magnetic fields are made to be substantially even has been illustrated in the three embodiments described above, the present invention may be applied also to a convergence apparatus in which only one of the horizontal and vertical bipolar magnetic fields is made substantially even. Further, it is a matter of cause that the case where the turn ratio of coils and the core protrusion mount angle are different a little from those in the above embodiments is included within the scope of the present invention so long as the difference does not cause any problem in performance for formation of a substantially even bipolar magnetic field. Particularly in the case where each magnetic pole is constituted by three core protrusions, it is possible to obtain a bipolar magnetic field having an optimum magnetic field shape in accordance with the sizes and shapes of the deflection yoke and the cathode-ray tube respectively, by desiredly changing the ratio of the number of turns of the coil wound on the core protrusion located on the magnetic field symmetry axis to the number of turns of the coil wound on each of the core protrusions located on the both sides of and symmetrically with respect to the magnetic field symmetry axis. Further, the case where the magnetic field shape of the bipolar magnetic field is adjusted by changing the turn ratio of coils while the convergence correction currents passed through the respective coils are made equal to each other is illustrated in the above embodiments, it is a matter of cause that a bipolar magnetic field having the same magnetic field shape can be obtained even in the case where the ratio of the convergence correction currents passed through the respective coils is selected to have a value corresponding to the turn ratio of coils in the above embodiments while the numbers of turns of the coils are made equal to each other. FIG. 15 is a sectional view showing a fourth embodiment of a convergence yoke of a convergence apparatus according to the present invention, FIG. 16 is a side view in the direction of XVI--XVI in FIG. 15 from the right side thereof, and FIG. 17 is a plan view of the magnetic auxiliary plate shown in FIG. 15. In FIG. 15, reference numerals 19, 19', 20 and 20' designate input terminals; 21a and 21a' vertical deflection coils; 22b and 22b' designate horizontal deflection coils; 23a, 23a', 23b and 23b' designate magnetic auxiliary plates; 54 designates a core; and a, a', b and b' designate core protrusions. As shown in FIG. 15 which is a front view viewed in the direction of the tube axis, the core 54 is arranged in a manner so that the pair of core protrusions a and a' and the pair of core protrusions b and b' are located on the magnetic field symmetry axes, that is, the horizontal and vertical axes, respectively, so as to inward projected from the ring-like portion of the core 54. All the numbers of turns of the coils 21a and 21a' wound on the respective core protrusions a and a' located in opposition to each other and of the coils 22b and 22b' wound on the respective core protrusions b and b' located in opposition to each other are made equal. When convergence correction currents are made to flow between the input terminals 19 and 19' and between the input terminals 20 and 20' respectively, two bipolar magnetic fields are generated in the horizontal and vertical directions. The magnetic auxiliary plates 23a, 23a', 23b and 23b' each having a fork end shape as shown in FIG. 17 are attached on the front ends of the respective core protrusions a, a', b and b'. The width of the fork end of each of the magnetic auxiliary plates 23a, 23a', 23b and 23b' is selected to fall within an angular range of 45° at maximum from the magnetic field symmetry axis (horizontal/vertical axis). The magnetic auxiliary plates 23a and 23a' provided on the respective core protrusions a and a' located on the horizontal axis are different in projecting direction from the magnetic auxiliary plates 23b and 23b' provided on the respective core protrusions b and b' located on the vertical axis. In such a configuration, in the generated bipolar magnetic fields, the magnetic field components at the peripheral portions are emphasized by the magnetic flux components leaking from the fork end portion of each of the magnetic auxiliary plates 23a, 23a', 23b and 23b' to the opposing magnetic pole to thereby reduce the barrel magnetic field component. FIG. 18 is an explanatory view showing comparison of the distribution, along a tube axis, of an uneven magnetic field component of a bipolar magnetic field generated in the convergence yoke of FIG. 15 between the cases where the magnetic auxiliary plates are provided and not provided. In FIG. 18, the reference numeral 13 represents the distribution curve of B 2 /B 0max in the case where the magnetic auxiliary plates are provided and 13' represents the distribution curve of B 2 /B 0max in the case where the magnetic auxiliary plates are not provided. FIG. 18 clearly shows that the provision of the magnetic auxiliary plates 23a, 23a', 23b and 23b' on the respective core protursions a, a', b and b' improves the value of B 2 /B 0max from the distribution curve 13' to the distribution curve 13' so as to reduce the barrel magnetic field component. Also in this embodiment, therefore, the degree of distortion of the electron beam spot due to the generated bipolar magnetic field can be reduced to thereby improve the focusing performance more than the conventional convergence apparatus. Since the projecting direction is made different between the magnetic auxiliary plates provided on the respective core protrusions located on the horizontal axis and the magnetic auxiliary plates provided on the respective core protrusions located on the vertical axis, the adjacent magnetic auxiliary plates do not come close to each other so that ineffective magnetic paths (magnetic paths generating magnetic flux which does not act on the electron beam) can be reduced to thereby prevent the reduction in deflection sensitivity of the convergence yoke. According to the present invention, accordingly, the bipolar magnetic field generated by the convergence yoke can be made substantially even or can be improved in the direction to have a substantially even magnetic field shape, so that the distortion of the electron beam spot at the time of convergence correction can be reduced to thereby improve the focusing performance. When the number of the core protrusions is increased, the air gap is reduced so that the effective core inner diameter is made small. Further, when the magnetic auxiliary plates projecting in the direction of the tube axis are provided, the effective magnetic field length (the magnetic field length in the direction of the tube axis, that is, the magnetic field length acting on the electron beam) is thereby elongated. These two features result in a remarkable effect in improvement in deflection sensitivity of the convergence yoke.

The disclosed relates to a convergence apparatus to be used for a single electron gun type cathode-ray tube, and relates to a convergence yoke to be used for the convergence apparatus. Each of two magnetic poles for generating a bipolar magnetic field is constituted by a first one of a plurality of core protrusions located on a horizontal or vertical axis and at least one pair of second ones of the plurality of core protrusions located at positions equiangularly and symmetrically deviated from the horizontal or vertical axis, and a ratio of an ampere turn of the coil wound on each of at least one pair of second core protrusions to an ampere turn of the coil wound on the first core protrusion is suitably changed. A firt magnetic auxiliary plate and a second magnetic auxiliary plate are provided on a first core protrusion constituting each of a first pair of magnetic poles and on a second core protrusion constituting each of a second pair of magnetic poles respectively. Each of the first and second magnetic auxiliary plates has a fork end projected along an axis perpendicular to a horizontal axis as well as a vertical axis. The first and second magnetic auxiliary plates have respective widths existing within an angular range symmetrically deviated by 45° from the horizontal axis and within an angular range symmetrically deviated by 45° from the vertical axis respectively. Each of the first and second magnetic auxiliary plates has a substantially Y-shaped and axisymmetrical form.

BACKGROUND OF INVENTION [0001] This invention relates generally to managing compliance assurance and, more particularly, to network-based methods and systems for managing compliance assurance information. [0002] Compliance assurance (CA) information includes information relating to a business entity's compliance with applicable laws and regulations and/or internal business standards and policies. These laws and regulations and/or internal business standards and policies typically relate to areas such as the environment, health and safety, quality, legal, human resources, and corporate compliance. In at least some known cases, in order for a business entity to comply with applicable laws and regulations and/or internal business standards and policies, a particular facility within the business entity must perform certain CA tasks, including audits, within a specified period of time and submit a report or other documentation to an agency or a manager within the business entity. Many of these CA tasks must be performed on a routine basis at the facility. [0003] Likewise, other facilities within the business entity might also have to perform and report identical, similar, or different CA tasks. In addition, if a facility is found to be in non-compliance, the facility might be required to take certain action to become compliant and might have to submit documentation showing its compliance. For business entities having numerous employees located in multiple divisions worldwide, managing CA information, which might include scheduling the CA tasks to be performed at each facility, reminding an assigned contact person at each facility of the upcoming CA tasks to be performed, confirming that the required CA tasks have been performed in a timely manner at each facility, properly documenting the CA tasks performed at each facility, and confirming that each facility within the business entity is in compliance with applicable laws and regulations and/or internal business standards and policies, is a major challenge. Failure to properly schedule, perform, and report the CA tasks, including audits, can result in delayed system operations, extended or additional maintenance, increased costs, and, in some cases, civil and/or criminal penalties. SUMMARY OF INVENTION [0004] In on aspect, a method for managing, storing, and disseminating compliance assurance (CA) information using a web-based system is provided. The system employs a server system coupled to a centralized interactive database and at least one client system. The method includes receiving CA information from a client system, storing CA information into a centralized database, cross-referencing CA information, updating the centralized database periodically to maintain CA information, providing CA information in response to an inquiry; and notifying users electronically of CA tasks and CA deadlines. [0005] In another aspect, a method for managing, storing, and disseminating compliance assurance (CA) information using a web-based system is provided. The system employs a server system coupled to a centralized interactive database, at least one managerial user system, and at least one client system. The CA information includes at least one of site information, a CA calendar, a CA audit tracking system, a CA audit tool, and CA contacts information. The method includes the steps of receiving CA information from a client system, storing CA information into a centralized database, cross-referencing CA information, updating the centralized database periodically to maintain CA information, providing CA information in response to an inquiry, notifying users electronically of CA tasks and CA deadlines, and providing an electronic report of the CA audit tracking system and the CA calendar to the managerial user system. [0006] In another aspect, a method for manipulating Compliance Assurance (CA) information using a web-based system is provided. The system employs a server system coupled to a centralized interactive database and at least one client system. The CA information includes at least one of business information, organizational information, site information, assigned contact person information, COE/department information, building information, CA audit tracking information, CA task information, CA calendar information, CA task reminder information, frequency of reminder information, environmental information, health and safety information, quality information, legal information, human resources information, management information, and corporate compliance information. The method includes receiving CA information, storing CA information into the centralized database, and cross-referencing CA information including creating a CA calendar based on at least one of CA tasks to be performed, a change in other previously created CA calendars, and a change in CA audit tracking information. The method further includes updating the centralized database with CA information including adding and deleting information so as to revise existing CA information including at least one of CA task information, CA calendar information, and CA audit tracking information. The method also includes providing CA information including at least one of business information, organizational information, site information, assigned contact person information, COE/department information, building information, CA audit tracking information, CA task information, CA calendar information, CA task reminder information, frequency of reminder information, environmental information, health and safety information, quality information, legal information, human resources information, management information, and corporate compliance information, in response to an inquiry, including downloading requested information from the server system and displaying requested information on the client system, the inquiry including utilizing at least one pull-down lists, check boxes, and hypertext links. Additionally, the method includes notifying users of CA tasks and CA deadlines including transmitting an electronic message to the client system from the server system notifying the user of a CA task to be performed. [0007] In another aspect, a method for manipulating Compliance Assurance (CA) information using a web-based system is provided. The system employs a server system coupled to a centralized interactive database, at least one managerial user system, and at least one client system. The CA information includes at least one of business information, organizational information, site information, assigned contact person information, COE/department information, building information, CA audit tracking information, CA task information, CA calendar information, CA task reminder information, frequency of reminder information, environmental information, health and safety information, quality information, legal information, human resources information, management information, and corporate compliance information. The method includes receiving CA information, storing CA information into a centralized database, cross-referencing CA information including creating a CA calendar based on at least one of CA tasks to be performed, a change in other previously created CA calendars, and a change in CA audit tracking information. The method further includes updating the centralized database with CA information including adding and deleting information so as to revise existing CA information including at least one of CA task information, CA calendar information, and CA audit tracking information. The method also includes providing CA information including at least one of business information, organizational information, site information, assigned contact person information, COE/department information, building information, CA audit tracking information, CA task information, CA calendar information, CA task reminder information, frequency of reminder information, environmental information, health and safety information, quality information, legal information, human resources information, management information, and corporate compliance information, in response to an inquiry, including downloading requested information from the server system and displaying requested information on the client system, the inquiry including utilizing at least one pull-down lists, check boxes, and hypertext links. Additionally, the method includes notifying users of CA tasks and CA deadlines including transmitting an electronic message to the client system from the server system notifying the user of a CA task to be performed, and providing an electronic report to the managerial user system including transmitting an electronic report to the managerial user system from the server system including a summary of the CA tasks performed at a site location for a time period shown on the CA calendar such that managerial oversight of the CA information is facilitated and compliance with certain laws, rules, regulations, standards, and policies relating to certain topics including at least one of environment, health and safety, quality, legal, and corporate compliance is assured. [0008] In another aspect, a network based system for managing, storing, and disseminating Compliance Assurance (CA) information is provided. The system includes a client system with a browser, a centralized database for storing information, and a server system configured to be coupled to said client system and said database. The server system is further configured to receive CA information from the client system, store CA information into the centralized database, cross-reference CA information, update the centralized database periodically to maintain CA information, provide CA information in response to an inquiry, and notify users electronically of CA tasks and CA deadlines. [0009] In another aspect, a network based system for managing, storing, and disseminating Compliance Assurance (CA) information is provided. The CA information includes at least one of site information, a CA audit tracking system, a CA calendar, a CA audit tool, and contact information. The system includes a client system with a browser, a managerial user system with a browser, a centralized database for storing information, and a server system configured to be coupled to the client system, the managerial user system, and the database. The server system is further configured to receive CA information from the client system, store CA information into the centralized database, cross-reference CA information, update the centralized database periodically to maintain CA information, provide CA information in response to an inquiry, notify users electronically of CA tasks and CA deadlines, and provide an electronic report of the CA audit tracking system and the CA calendar to the managerial user system. [0010] In another aspect, a computer program embodied on a computer readable medium for managing, storing, and disseminating Compliance Assurance (CA) information is provided. The program includes a code segment that receives CA information and then maintains a database by adding, deleting and updating CA information. The program also generates at least one CA calendar based on the received CA information, manages at least one CA audit tracking system based on the received CA information, and provides the CA calendar, the CA audit tracking system, a CA audit tool system, and contact information to users. The program also notifies users of CA tasks and CA deadlines, and provides a report of the CA audit tracking system and the CA calendar. BRIEF DESCRIPTION OF DRAWINGS [0011] [0011]FIG. 1 is a simplified block diagram of a Compliance Assurance Coordination System (CACS) in accordance with one embodiment of the present invention. [0012] [0012]FIG. 2 is an expanded version block diagram of an exemplary embodiment of a server architecture of the CACS. [0013] [0013]FIG. 3 shows a configuration of a database within the database server of the server system including other related server components. [0014] [0014]FIG. 4 is a flowchart of the processes employed by CACS to facilitate use. [0015] [0015]FIG. 5 is an exemplary embodiment of a user interface displaying a home page of CACS. [0016] [0016]FIG. 6 is an exemplary embodiment of a user interface of CACS displaying a Compliance Calendar. [0017] [0017]FIG. 7 is an exemplary embodiment of a user interface of CACS displaying an Add/Edit Task page for the Compliance Calendar. [0018] [0018]FIG. 8 is an exemplary embodiment of a user interface of CACS displaying a Charts page for the Compliance Calendar. [0019] [0019]FIG. 9 is an exemplary embodiment of a user interface of CACS displaying a monthly task compliance summary report. [0020] [0020]FIG. 10 is an exemplary embodiment of a user interface of CACS displaying a monthly task compliance status report. [0021] [0021]FIG. 11 is an exemplary embodiment of a user interface of CACS displaying an Audit Tracking System. [0022] [0022]FIG. 12 is an exemplary embodiment of a user interface of CACS displaying an Add/Edit Task page for the Audit Tracking System. [0023] [0023]FIG. 13 is an exemplary embodiment of a user interface of CACS displaying a Charts page for the Audit Tracking System. [0024] [0024]FIG. 14 is an exemplary embodiment of a user interface of CACS displaying a bi-weekly audit findings status report. [0025] [0025]FIG. 15 is an exemplary embodiment of a user interface of CACS displaying a bi-weekly audit findings summary report. [0026] [0026]FIG. 16 is an exemplary embodiment of a user interface of CACS displaying an Audit Tool. [0027] [0027]FIG. 17 is an exemplary embodiment of a user interface of CACS displaying a selected audit tool checklist. [0028] [0028]FIG. 18 is an exemplary embodiment of a user interface of CACS displaying an audit checklist summary. [0029] [0029]FIG. 19 is an exemplary embodiment of a user interface of CACS displaying an audit findings report. [0030] [0030]FIG. 20 is an exemplary embodiment of a user interface of CACS displaying a Contacts Homepage. [0031] [0031]FIG. 21 is an exemplary embodiment of a user interface of CACS displaying a page for inputting a contact person's contact information. [0032] [0032]FIG. 22 is a list of at least some of the data tables and key fields used by CACS. [0033] [0033]FIG. 23 is another list of at least some of the data tables and key fields used by CACS. [0034] [0034]FIG. 24 is another list of at least some of the data tables and key fields used by CACS. DETAILED DESCRIPTION [0035] Exemplary embodiments of systems and processes that facilitate integrated network-based electronic reporting and workflow process management related to a Compliance Assurance Coordination System (CACS) are described below in detail. The systems and processes facilitate, for example, electronic submission of information using a client system, automated extraction of information, and web-based reporting for internal and external system users. The CACS allows a business entity to conduct and manage its own internal assessments and audit tracking to assure its compliance with certain laws, rules, regulations, standards, and policies relating to certain topics including at least one of the environment, health and safety, quality, legal, and corporate compliance. [0036] In the exemplary embodiment, the CACS collects, tracks, displays, schedules, and disseminates real time information regarding Compliance Assurance (CA) information for a site location within a business entity. CA information includes at least one of business information, organizational information, site information, assigned contact person information, COE/department information building information, CA audit tracking information, CA task information, CA calendar information, CA task reminder information, frequency of reminder information, CA contacts information, environmental information, health and safety information, quality information, legal information, human resources information, management information, and corporate compliance information. In addition, the CACS electronically notifies the users of upcoming CA tasks and CA deadlines, and provides a summary report to a managerial user, which describes at least the CA tasks performed at a site location during a specific period of time. [0037] In addition, a network-based CACS collects, tracks, displays, schedules, and disseminates real time information regarding a CA calendar. The CA calendar shows the CA tasks to be performed at a selected site location within a business entity during a specified period of time. In another embodiment, the CACS collects, tracks, displays, schedules and disseminates information regarding a CA audit tracking system. The CA audit tracking system tracks the CA tasks performed at each site location, records the findings from the CA tasks, documents the findings for purposes of reporting to an agency or the business entity's management, assures compliance with the certain laws, rules, regulations, standards, and policies, and, if non-compliance is found, tracks the corrective actions taken at the site location. In another embodiment, the CACS includes both the CA calendar and the CA audit tracking system and further includes a CA audit tool system and CA contacts information. The CA audit tool system provides a plurality of audit checklists to help a user in conducting various audits at the site location. The CA contacts information provides information relating to persons associated with certain CA tasks and CA audits. The CA calendar, the CA audit tracking system, the CA audit tool system, and the CA contacts information in the CACS are used by multiple site locations within a business entity, namely each site location or facility subject to compliance with laws, rules, regulations, standards, and policies relating to at least one of environment, health and safety, quality, legal, and corporate compliance. [0038] CA information relating to each site location within a business entity is received by the CACS which stores the CA information in a database, updates the database with CA information received, cross-references the CA information received, provides CA information in response to an inquiry, notifies a user electronically of CA tasks and CA deadlines, and provides a report to at least one managerial user of the CA tasks performed at specific site locations for a specified period of time. [0039] In the CACS, CA information is stored in the database. The network based CACS provides convenient access to CA information, including original schedules, preliminary schedules and confirmed schedules. Once into the CACS home page, the user has an option to access the CA calendar, the CA audit tracking system, the CA audit tool, or the CA contacts homepage and access CA information for a specific site location. In an exemplary embodiment, for each site location, an authorized user can access the CA information. [0040] In one embodiment, the system is a computer program embodied on a computer readable medium implemented utilizing a Structured Query Language (SQL) with a client user interface front-end for administration and a web interface for standard user input and reports. In an exemplary embodiment, the system is web enabled and is run on a business-entity's intranet. In yet another embodiment, the system is fully accessed by individuals having an authorized access outside the firewall of the business-entity through the Internet. In a further exemplary embodiment, the system is being run in a Windows NT environment. The application is flexible and designed to run in various different environments without compromising any major functionality. [0041] The systems and processes are not limited to the specific embodiments described herein. In addition, components of each system and each process can be practiced independent and separate from other components and processes described herein. Each component and process also can be used in combination with other assembly packages and processes. [0042] [0042]FIG. 1 is a simplified block diagram of a Compliance Assurance Coordination System (CACS) 10 including a server system 12 , and a plurality of client sub-systems, also referred to as client systems 14 , connected to server system 12 . In one embodiment, client systems 14 are computers including a web browser, such that server system 12 is accessible to client systems 14 via the Internet. Client systems 14 are interconnected to the Internet through many interfaces including a network, such as a local area network (LAN) or a wide area network (WAN), dial-in-connections, cable modems and special high-speed ISDN lines. Client systems 14 could be any device capable of interconnecting to the Internet including a web-based phone, personal digital assistant (PDA), or other web-based connectable equipment. A database server 16 is connected to a database 20 containing information on a variety of matters, as described below in greater detail. In one embodiment, centralized database 20 is stored on server system 12 and can be accessed by potential users at one of client systems 14 by logging onto server system 12 through one of client systems 14 . In an alternative embodiment database 20 is stored remotely from server system 12 and may be non-centralized. [0043] [0043]FIG. 2 is an expanded version block diagram of an exemplary embodiment of a server architecture of a CACS 22 . Components in system 22 , identical to components of system 10 (shown in FIG. 1), are identified in FIG. 2 using the same reference numerals as used in FIG. 1. System 22 includes server system 12 and client systems 14 . Server system 12 further includes database server 16 , an application server 24 , a web server 26 , a fax server 28 , a directory server 30 , and a mail server 32 . A disk storage unit 34 is coupled to database server 16 and directory server 30 . Servers 16 , 24 , 26 , 28 , 30 , and 32 are coupled in a local area network (LAN) 36 . In addition, a system administrator's workstation 38 , a user workstation 40 , and a supervisor's workstation 42 are coupled to LAN 36 . Alternatively, workstations 38 , 40 , and 42 are coupled to LAN 36 via an Internet link or are connected through an Intranet. [0044] Each workstation, 38 , 40 , and 42 is a personal computer having a web browser. Although the functions performed at the workstations typically are illustrated as being performed at respective workstations 38 , 40 , and 42 , such functions can be performed at one of many personal computers coupled to LAN 36 . Work stations 38 , 40 , and 42 are illustrated as being associated with separate functions only to facilitate an understanding of the different types of functions that can be performed by individuals having access to LAN 36 . [0045] Server system 12 is configured to be communicatively coupled to various individuals, including employees 44 and to third parties, e.g., internal or outside consultants, 46 via an ISP Internet connection 48 . The communication in the exemplary embodiment is illustrated as being performed via the Internet, however, any other wide area network (WAN) type communication can be utilized in other embodiments, i.e., the systems and processes are not limited to being practiced via the Internet. In addition, and rather than WAN 50 , local area network 36 could be used in place of WAN 50 . [0046] In the exemplary embodiment, any authorized individual having a workstation 54 can access CACS 22 . At least one of the client systems includes a manager workstation 56 located at a remote location. Work stations 54 and 56 are personal computers having a web browser. Also, work stations 54 and 56 are configured to communicate with server system 12 . Furthermore, fax server 28 communicates with remotely located client systems, including a client system 56 via a telephone link. Fax server 28 is configured to communicate with other client systems 38 , 40 , and 42 as well. [0047] [0047]FIG. 3 shows a configuration of database 20 within database server 16 of server system 12 shown in FIG. 1. Database 20 is coupled to several separate computer software components within server system 12 , which perform specific tasks. Server system 12 includes a collection component 64 for collecting data from users in database 20 , a tracking component 66 for tracking data, and a displaying component 68 to display information. Tracking component 66 tracks and cross-references data, including modifying existing data. Server system 12 also includes a receiving component 70 to receive a specific query from client system 14 , and an accessing component 72 to access database 20 within data storage device 34 . Receiving component 70 is programmed for receiving a query from one of a plurality of users. Server system 12 further includes a processing component 76 for searching and processing received queries against database 20 containing a variety of information collected by collection component 64 . An information fulfillment component 78 , located in server system 12 , downloads the requested information to the plurality of users in response to the requests received by receiving component 70 . Information fulfillment component 78 downloads the information after the information is retrieved from database 20 by a retrieving component 80 . Retrieving component 80 retrieves, downloads and sends information to client system 14 based on a query received from client system 14 . [0048] Retrieving component 80 further includes a display component 84 configured to download information to be displayed on a client system's graphical user interface and a printing component 86 configured to print information. Retrieving component 80 generates reports requested by the user through client system 14 in a pre-determined format. System 10 is flexible to provide other alternative types of reports and is not constrained to the options set forth above. [0049] Server system 12 also includes a notifying component 88 and a providing component 90 . Notifying component 88 electronically transmits a message to client system 14 based on information inputted into server system 12 notifying a user of CA tasks to be performed and a CA schedule for performing those tasks. Providing component 90 electronically provides a report to manager workstation 56 (shown in FIG. 2) summarizing the CA tasks performed at a specific site location and the time period in which those CA tasks were performed. [0050] In one embodiment, collection component 64 , tracking component 66 , displaying component 68 , receiving component 70 , processing component 76 , information fulfillment component 78 , retrieving component 80 , display component 84 , printing component 86 , notifying component 88 , and providing component 90 are computer programs embodied on computer readable medium. [0051] Database 20 is divided into a Plant Information Section (PIS) 92 , a CA Calendar Section (CCS) 94 , a CA Audit Tracking System Section (CAATSS) 96 , a CA Audit Tool Section (CAATS) 98 , and a CA Contacts Section (CAS) 100 . PIS 92 contains information specific to each plant within the business entity. PIS 92 , CCS 94 , CAATSS 96 , CAATS 98 , and CAS 100 facilitate database 20 storage of CA information 102 . [0052] PIS 90 includes CA information 102 for each site location or plant including, but not limited to, organizational information 104 , site information 106 , assigned contact person information 108 , COE/department information 110 , and building information 112 . [0053] CCS 94 contains CA information 102 relating to scheduling CA tasks. In one embodiment, CCS 94 includes at least one of CA task information 114 , CA calendar information 116 , CA task reminder information 118 , CA task reminder archive information 120 , and frequency of reminder information 122 . Revisions or modifications to one stored CA calendar can effect other related CA calendars. Tracking component 66 also updates database 20 as it revises CA calendars. [0054] CAATSS 96 contains CA information 102 relating to CA audits. In one embodiment, CAATSS 96 includes at least one of CA audit tracking information 124 , type of audit 126 , categories for findings in audit 128 , and closure categories in audit 130 . Revisions or modifications to CA audit tracking information 124 can effect CA calendar information 116 . Tracking component 66 also updates database 20 as it revises CA audit tracking information 124 . [0055] CAATS 98 contains CA information 102 including a plurality of audit checklists 132 . Audit checklists 132 might be used by a user performing a CA audit. CAS 100 contains CA information 102 including at least CA contact information. 134 . CA contact information 134 includes information relating to contact persons that might provide help in performing certain CA audits and CA tasks. [0056] System 10 accumulates a variety of confidential data. Therefore, system 10 has different access levels to control and monitor the security of the system. Authorization for access is assigned by system administrators on a need to know basis. In one embodiment, system 10 provides access based on job functions. In yet another embodiment, system 10 provides access based on business-entity. The administration/editing capabilities within system 10 are also restricted to ensure that only authorized individuals have access to modify or edit the data existing in the system. System 10 manages and controls access to system data and information. [0057] The architectures of system 10 as well as various components of system 10 are exemplary only. Other architectures are possible and can be utilized in connection with practicing the processes described below. [0058] [0058]FIG. 4 is a flowchart 200 of the processes employed by system 10 to facilitate use. Initially, the user accesses 210 a user interface such as a home page 220 of the web site through client system 14 (shown in FIG. 1). In one embodiment, client system 14 , as well as server system 12 , are protected from access by unauthorized individuals. The user logs-in 230 to system 10 using a password (not shown) or an employee payroll number for security. Client system 14 is configured to receive 232 an electronic notice of CA tasks and CA deadlines from server system 12 . Client system 14 displays 240 options available to the user through links, check boxes, or pull-down lists. Once the user selects 244 an option (in one embodiment, relating to site location and CA task type) from the available links, the request is transmitted 248 to server system 12 . Transmitting 248 the request is accomplished, in one embodiment, either by click of a mouse or by a voice command. Once server system 12 (shown in FIG. 1) receives 252 the request, server system 12 accesses 256 database 20 (shown in FIG. 1). System 10 determines 260 if additional narrowing options are available. In one embodiment, additional narrowing options include CA calendar and CA audit tracking selection pull-down lists. If additional narrowing options are available 264 , system 10 displays 240 the options relating to the prior option selected by the user on client system 14 . The user selects 244 the desired option and transmits the request 248 . Server system 12 receives the request 252 and accesses 256 database 20 . When system 10 determines that additional options 260 are not available 268 , system 10 retrieves 272 requested information from database 20 . The requested information is downloaded 276 and provided 280 to client system 14 from server 12 . Client system 14 transmits a report 282 to manager workstation 56 (shown in FIG. 2) relating to the CA tasks performed at the specific site location for a specified period of time. The user can continue to search 284 database 20 for other information or exit 290 from system 10 . [0059] [0059]FIG. 5 is an exemplary embodiment of a user interface 300 displaying a home page of CACS 10 (shown in FIG. 1). User interface 300 requires the user to input an organization 302 and a site location 304 . The exemplary embodiment shows organization field 302 and site location field 304 as pull-down lists, however, other means for inputting this information could also be used, e.g., check boxes. User interface 300 is the entry point for anyone trying to access database 20 via the web. In addition, in the exemplary embodiment, user interface, i.e., web page, 300 provides a user with selectable hyperlink options including a Compliance Calendar 306 , an Audit Tracking System 308 , an Audit Tool 310 , a Contacts Homepage 312 , and an online tutorial 314 . After inputting the necessary information in organization 302 and site location 304 , the user selects between hyperlink options Compliance Calendar 306 , Audit Tracking System 308 , Audit Tool 310 , Contacts Homepage 312 , and online tutorial 314 . In another exemplary embodiment, user interface 300 provides the user with selectable pull-down list options, check boxes, or radio buttons. [0060] [0060]FIG. 6 is an exemplary embodiment of a user interface 350 displaying a home page of Compliance Calendar 306 (shown in FIG. 5). User interface 350 displays a CA calendar 352 for a selected site location. CA calendar 352 also shows CA tasks 354 to be performed on certain specified days at the site location and an assigned contact person 356 for those tasks. Pull-down list 358 allows the user to display CA tasks 354 based on the assigned contact person 356 . In the exemplary embodiment, CA tasks 354 are hyperlinks which allow the user to select and display additional information relating to selected CA task 354 . User interface 350 also provides selectable hyperlinks including at least one of an Add/Edit Tasks link 360 , Charts link 362 , Reports link 364 , and Logoff link 366 . Add/Edit Tasks link 360 allows the user to add and/or edit the CA information inputted for selected CA task 354 , including the scheduling of selected CA task 354 . Charts link 362 allows the user to chart the CA information by CA task 354 , assigned contact person 356 , and time period. Reports link 364 allows a user to electronically notify other users and designate an assigned contact person for upcoming CA tasks and CA deadlines. [0061] [0061]FIG. 7 illustrates an example user interface 400 associated with Add/Edit Tasks link 360 (shown in FIG. 6). User interface 400 , i.e., web page, shown in FIG. 7 is an example only and there are a plurality of variations possible. User interface 400 displays a selected CA task 402 , a task date 404 , an assigned contact person 406 , a task category 408 , a task status 410 , a task plan 412 , whether the task is a regulatory obligation 414 , task frequency, 416 , and a number of days prior to when a notice email should be sent 418 . User interface 400 also allows the user to add and/or edit CA information 420 associated with selected task 402 , including the task date 404 . [0062] [0062]FIG. 8 illustrates an example user interface 450 associated with Charts link 362 (shown in FIG. 6). User interface 450 , i.e., web page, shown in FIG. 8 is an example only and there are a plurality of variations possible. User interface 450 displays a bar graph 452 showing CA calendar tasks 454 by a responsible person 456 , and further shows CA calendar tasks 454 as either Open Past Due, Closed, or Open. Web-page 450 further allows a user to chart based on calendar tasks start date 458 and end date 460 . [0063] [0063]FIG. 9 illustrates an example user interface 500 displaying a monthly task compliance summary report 502 for certain selected site locations. Summary report 502 is transmitted to an assigned business manager workstation 56 (shown in FIG. 2). User interface 500 , i.e., web page, shown in FIG. 9 is an example only and there are a plurality of variations possible. User interface 500 displays summary report 502 for each site 504 assigned to the manager user. Summary report 502 also displays the following information for each site 504 : active tasks 506 , tasks completed year to date 508 , total tasks year to date 510 , percentage of tasks completed year to date 512 , total tasks past due 514 , assigned administrator 516 , and assigned managers 518 . Summary report 502 provides the manager user with a summary of the CA tasks performed at a selected site location for a selected period of time such that managerial oversight of the CA information is facilitated and compliance with certain laws, rules, regulations, standards, and policies relating to certain topics including at least one of environment, health and safety, quality, legal, and corporate compliance is assured. [0064] [0064]FIG. 10 illustrates an example user interface 550 displaying a monthly task compliance status report 552 for certain selected site locations. Status report 552 is transmitted to an assigned operations manager workstation 56 (shown in FIG. 2). User interface 550 , i.e., web page, shown in FIG. 10 is an example only and there are a plurality of variations possible. Web page 550 displays summary report 552 by assigned person 554 assigned to the managerial user. Summary report 552 also displays at least the following information for each assigned person 554 : monthly completed tasks 556 , total monthly tasks 558 , percentage of monthly tasks completed 560 , year to date completed tasks 562 , year to date total tasks 564 , percentage of year to date tasks completed 566 , and total tasks past due 568 . Summary report 552 provides the managerial user with a summary of the CA tasks performed at an assigned site location for a selected period of time such that managerial oversight of the CA information is facilitated and compliance with certain laws, rules, regulations, standards, and policies relating to certain topics including at least one of environment, health and safety, quality, legal, and corporate compliance is assured. [0065] [0065]FIG. 11 is an exemplary embodiment of a user interface 600 displaying a home page of Audit Tracking System 308 (shown in FIG. 5). User interface 600 displays a CA Audit Tracking System 602 for a selected site location. In the exemplary embodiment, CA Audit Tracking System 602 displays pull-lists prompting the user for the following: audit type 604 , audit name 606 , finding type 608 , responsible person 610 , category 612 , repeat finding 614 , center/department 616 , building/area 618 , workstation 620 , and finding reference 622 . Pull-down lists 604 , 606 , 608 , 610 , 612 , 614 , 616 , 618 , 620 , and 622 allow the user to input CA audit information. CA Audit Tracking System 602 also provides a status selection 624 which allows the user to display either Open CA audits or Closed CA audits or both. User interface 600 also provides selectable hyperlinks including an Add/Edit Tasks link 626 , Charts link 628 , Reports link 630 , and Logoff link 632 . Add/Edit Tasks link 626 allows the user to add and/or edit CA audit information inputted into CA Audit Tracking System 602 . Charts link 628 allows the user to chart CA audit information. Reports link 630 allows the user to electronically notify other users and designate an assigned contact person for upcoming CA audit tasks and CA audit deadlines. User interface 600 also has a Show Findings button 634 that allows the user to sort CA audit information through the use of radio buttons and display a status summary 636 . [0066] [0066]FIG. 12 illustrates an example user interface 650 associated with Add/Edit Tasks link 626 (shown in FIG. 11) shown on CA Audit Tracking System user interface 600 (shown in FIG. 11). User interface 650 , i.e., web page, shown in FIG. 12 is an example only and there are a plurality of variations possible. In the exemplary embodiment, user interface 650 prompts the user to input CA audit information with a plurality of pull-down lists including: finding date 652 , finding type 654 , number of items in finding 656 , repeat finding 658 , responsible person 660 , auditor/contact person 662 , audit type 664 , audit name/number 666 , finding category 668 , center/department 670 , building 672 , workstation 674 , and contact phone 676 . Pull-down lists 652 , 654 , 656 , 658 , 660 , 662 , 664 , 666 , 668 , 670 , 672 , 674 , and 676 allow the user to add and/or edit the CA audit information. [0067] [0067]FIG. 13 illustrates an example user interface 700 associated with Charts link 628 (shown in FIG. 11) shown on CA Audit Tracking System user interface 600 (shown in FIG. 11). User interface 700 , i.e., web page, shown in FIG. 13 is an example only and there are a plurality of variations possible. User interface 700 allows the user to chart CA audit information based on at least the following: scope and date 702 , findings as desired 704 , chart by 706 , and select chart stacking and show top 708 . In the exemplary embodiment, user interface 700 prompts the user under topics 702 , 704 , 706 , and 708 to input CA audit information through a plurality of pull-down lists, data fields, and radio buttons. [0068] [0068]FIG. 14 illustrates an example user interface 750 displaying a bi-weekly audit findings status report 752 for selected site locations. Status report 752 is transmitted to assigned site manager, operations manager, and responsible person at manager workstations 56 (shown in FIG. 2). User interface 750 shown in FIG. 14 is an example only and there are a plurality of variations possible. User interface 750 displays summary report 752 of open audit findings 754 . Open audit findings 754 is further shown on user interface 750 as open findings 756 and open past due findings 758 . Summary report 752 provides the manager users with a summary of CA audit information for a selected site location for a selected period of time such that managerial oversight of the CA audit information is facilitated and compliance with certain laws, rules, regulations, standards, and policies relating to certain topics including at least one of environment, health and safety, quality, legal, and corporate compliance is assured. [0069] [0069]FIG. 15 illustrates an example user interface 800 displaying a bi-weekly audit findings summary report 802 for selected site locations. Summary report 802 is transmitted to assigned business manager workstation 56 (shown in FIG. 2). User interface 800 shown in FIG. 15 is an example only and there are a plurality of variations possible. User interface 800 displays summary report 802 for each selected site location 804 and displays an assigned administrator 806 , an assigned manager 808 , a last finding date 810 , an audit days old section 812 , and an audit closure rate section 814 . Summary report 802 provides the business manager user with a summary of the CA audit information at selected site locations for a selected period of time such that managerial oversight of the CA audit information is facilitated and compliance with certain laws, rules, regulations, standards, and policies relating to certain topics including at least one of environment, health and safety, quality, legal, and corporate compliance is assured. [0070] [0070]FIG. 16 is an exemplary embodiment of a user interface 850 displaying a home page of Audit Tool 310 (shown in FIG. 5). User interface 850 shown in FIG. 16 is an example only and there are a plurality of variations possible. User interface 850 allows a user to access a plurality of audit checklists 852 . In the exemplary embodiment, audit checklists 852 are hyperlinks that allow the user to access and display a selected audit checklist. Audit checklists 852 are categorized by topic. User interface 850 displays at least one of the following audit checklist category topics: U.S. Environmental 854 , U.S. Health & Safety 856 , U.S. DOT 858 , U.S. Construction Safety 860 , and U.S. Health & Safety Special Industries 862 . In the exemplary embodiment, the audit checklist category topics shown on user interface 850 are hyperlinks that allow the user to access and display the audit checklists associated with the selected category. In addition, user interface 850 allows the user to sort and display audit checklists 852 based on applicability. In the exemplary embodiment, an applicability sort function 864 uses radio buttons that include: Master 866 , Laboratory Areas 868 , Manufacturing/Shop Appl. Servicing 870 , and Office 872 . Although radio buttons are shown for applicability sort function 864 , other such inputting means could also be employed, including pull-down lists, check boxes, or hyperlinks. User interface 850 also allows a user to save a selected audit checklist. [0071] [0071]FIG. 17 illustrates an example user interface 900 of a selected audit tool checklist 852 (shown in FIG. 16). User interface 900 shown in FIG. 17 is an example only and there are a plurality of variations possible. In the exemplary embodiment, user interface 900 displays a plurality of pull-down menus and data fields that allow a user to input information relating to a selected site location and selected audit checklist 852 . The pull-down menus and data fields include the following: Organization 902 , Site 904 , Location Detail 906 , Audit dates 908 , Auditors & General Comments 910 . User interface 900 also provides an Update and Save button 912 , a Make Report button 914 , a Print Checklist button 916 , and instructions 918 on responding to selected audit tool checklist 852 . [0072] [0072]FIG. 18 illustrates an example user interface 950 of a saved audit checklist summary 952 . Saved audit checklist summary 952 is associated with an audit checklist selected from audit checklists 852 (shown in FIG. 16). User interface 950 shown in FIG. 18 is an example only and there are a plurality of variations possible. [0073] Saved audit checklist summary 952 provides the user with a summary of the CA audit information at selected site locations for a selected period of time such that oversight of the CA audit information is facilitated and compliance with certain laws, rules, regulations, standards, and policies relating to certain topics including at least one of environment, health and safety, quality, legal, and corporate compliance is assured. [0074] [0074]FIG. 19 illustrates an example user interface 1000 of an audit findings report 1002 . Audit findings report 1002 is associated with an audit checklist selected from audit checklists 852 (shown in FIG. 16). User interface 1000 shown in FIG. 19 is an example only and there are a plurality of variations possible. Audit findings report 1002 provides the user with a summary of the CA audit information at selected site locations for a selected period of time such that oversight of the CA audit information is facilitated and compliance with certain laws, rules, regulations, standards, and policies relating to certain topics including at least one of environment, health and safety, quality, legal, and corporate compliance is assured. [0075] [0075]FIG. 20 is an exemplary embodiment of a user interface 1050 displaying a home page of Contacts Homepage 312 (shown in FIG. 5). User interface 1050 shown in FIG. 20 is an example only and there are a plurality of variations possible. User interface 1050 allows a user to search for a contact person and access the contact person''s contact information. The contact person would be involved with at least one CA audit tasks. In the exemplary embodiment, a pull-down list of contact persons 1052 is provided on user interface 1050 . The user can select a contact person from pull-down list 1052 . In addition, user interface 1050 provides a sorter 1054 for sorting contact persons on pull-down list 1052 . In the exemplary embodiment, the sorter includes an All Contacts link 1056 , a Location link 1058 , and an Organization link 1060 . User interface 1050 also provides a Contacts Details button 1062 which, when selected, provides the user with the selected contact person's contact information. [0076] [0076]FIG. 21 illustrates an example user interface 1100 for inputting a contact person's contact information 1102 . User interface 1100 shown in FIG. 21 is an example only and there are a plurality of variations possible. User interface 1100 allows a user to add or edit contact information 1102 . In the exemplary embodiment, user interface 1100 displays a plurality of pull-down lists and data fields that allow a user to input contact information 1102 . The pull-down lists and data fields include at least one of the following: Full Name 1104 , Title 1106 , First Name 1108 , DialComm Phone 1110 , Organization 1112 , Location 1114 , Building 1116 , Address 1118 , Last Name 1120 , External Phone 1122 , Fax 1124 , Cell Phone/Pager 126 , Home Phone 1128 , Internet Email Address 1130 , and Expertise/Responsibility 1132 . [0077] [0077]FIG. 22 is a list 1150 of at least some of the data tables 1152 and key fields 1154 used within Plant Information Section (PIS) 92 (shown in FIG. 3) in database 20 (shown in FIG. 3). List 1150 shown in FIG. 22 is an example only and there are a plurality of variations possible. List 1150 includes the information that might be used by either Compliance Calendar 306 or Audit Tracking System 308 (both shown in FIG. 5). Data tables 1152 shown on list 1150 include: Org. 1156 , Site 1158 , Contact 1160 , COE/department 1162 , and Building 1164 . The key fields 1154 shown below data table Org. 1156 include: orgname 1166 , table 1168 , orgpassword 1170 , business 1172 , administrator 1174 , and suborg 1176 . The key fields 1154 shown below data table Site 1158 include: location 1178 , admin 1180 , password 1182 , suborg 1184 , atscc on 1186 , project 1188 , and subsite 1190 . The key fields 1154 shown below data table Contact 1160 include: contact name 1192 , contact last name 1194 , contact first name 1196 , contact phone 1198 , contact title 1200 , EHS dedicated 1202 , contact location 1204 , contact org 1206 , and contact email 1208 . The key fields 1154 shown below data table COE/department 1162 include: location 1210 , COE/department 1212 , subsite 1214 , and archive 1216 . The key fields 1154 shown below data table Building 1164 include: location 1218 , and building 1220 . [0078] [0078]FIG. 23 is a list 1300 of at least some of the data tables 1302 and key fields 1304 used within CA Audit Tracking System Section (CAATSS) 96 (shown in FIG. 3) in database 20 (shown in FIG. 3). List 1300 shown in FIG. 23 is an example only and there are a plurality of variations possible. Data tables 1302 shown on list 1300 include: Audit 1306 , Audit Type 1308 , Category 1310 , and Closure 1312 . The key fields 1304 shown below data table Audit 1306 include: location 1314 , ID 1316 , audit name 1318 , audit date 1320 , audit type 1322 , finding type 1324 , category 1326 , citation 1328 , numitems 1330 , repeatitem 1332 , classification type 1334 , COE/department 1336 , bldg 1338 , workstation 1340 , responperson 1342 , description 1344 , corrective action 1346 , contact person 1348 , contact phone 1350 , close date 1352 , close comment 1354 , close person 1356 , status 1358 , closure due date 1360 , update date 1362 , and update user 1364 . The key fields 1304 shown below data table Audit Type 1308 include: audit name 1366 , and audit group 1368 . The key fields 1304 shown below data table Category 1310 include: category 1370 , and super category 1372 . The key fields 1304 shown below data table Closure 1312 include: closure 1374 . [0079] [0079]FIG. 24 is a list 1400 of at least some of the data tables 1402 and key fields 1404 used within CA Calendar Section (CCS) 94 (shown in FIG. 3) in database 20 (shown in FIG. 3). List 1400 shown in FIG. 24 is an example only and there are a plurality of variations possible. Data tables 1402 shown on list 1400 include: Task 1406 , Calendar Media 1408 , Task Reminder 1410 , Task Reminder Archive 1412 , and Frequency 1414 . The key fields 1404 shown below data table Task 1406 include: location 1416 , task name 1418 , resp person 1420 , resp cc 1422 , mult cc 1424 , media 1426 , remind 1428 , first rem date 1430 , rem freq 1432 , rem days prior 1434 , reg comp 1436 , task plan 1438 , weblink 1440 , comp 1442 , comp date 1444 , project 1446 , and update date 1448 . The key fields 1404 shown below data table Calendar Media 1408 include: media 1450 . The key fields 1404 shown below data table Task Reminder 1410 include: location 1452 , task name 1454 , reminder date 1456 , resp person 1458 , complete 1460 , complete date 1462 , comment 1464 , and reminder plan 1466 . The key fields 1404 shown below data table Task Reminder Archive 1412 include: location 1468 , task name 1470 , reminder date 1472 , resp person 1474 , complete 1476 , complete date 1478 , comment 1480 , and reminder plan 1482 . The key fields 1404 shown below data table Frequency 1414 include: type 1484 . [0080] While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.

A method for managing, storing, and disseminating compliance assurance (CA) information using a web-based system is provided. The system employs a server system coupled to a centralized interactive database and at least one client system. The method includes receiving CA information from a client system, storing CA information into a centralized database, cross-referencing CA information, updating the centralized database periodically to maintain CA information, providing CA information in response to an inquiry; and notifying users electronically of CA tasks and CA deadlines.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an apparatus and method for automatically monitoring machining processes and particularly, for monitoring a machining processes, as a function of the machine's mechanical vibration and power consumption. 2.Description of Related Art Tool wear, loss of coolant, broken tools, and excessive vibrations are problems of machining apparatus and processes that use tools to grind, cut, drill, or in some way mechanically remove metal or other material during the machining process. These problems can cause reduced or unacceptable levels of quality, excessive scrap rates and increased production costs. During the grinding process dull tools, such as grinding wheels, or loss of machine coolant may easily go undetected by the machine operator and lead to sometimes expensive machinings having to be reground or scrapped altogether. The use of automated machining devices including robots, machining cells, and other unattended machines requires some means of machining process monitoring whether it be manual or automated. Several automated tool monitoring devices have been developed to monitor tool wear. These tool monitors produce signals that warn human operators to take corrective action or send signals to computerized machine controllers which then initiate automated corrective procedures. Prior tool monitoring devices use complicated and expensive probes that may require modification of the grinding machines or machining process. One such device is described in U.S. Pat. No. 4,295,301 entitled "Dressing Apparatus with Means for Detecting Grinding Wheel Wear", by Barth et al. and has a complex movable intrusive probe which must contact the grinding wheel and a probe movement detection device as well as an accelerometer. Acoustic energy sensor based tool monitoring systems have also been found to require frequent calibrations as well as requiring more complicated less accurate apparatus than that of the present invention. Other tool wear or condition monitors are known and used in the industry such as the ATAM system by IRD Mechanalysis which uses an accelerometer to produce a signal indicating vibrational patterns of machines which change as the cutting tool wears which requires a great deal of calibration each time a new tool is used. The WIBRA tool condition monitoring system produced by the WIBRA Company of Sweden, as described in their brochures which are incorporated herein by reference, uses only accelerometer data and requires that the system be recalibrated each time a new tool is used. It also is most accurate when the tool is damaged unlike the present invention which seeks to prevent production of a machining with less than minimum quality levels. SUMMARY OF THE INVENTION The present invention provides a machining process monitor and method to monitor the machining process as a function of mechanical vibration levels and machine power consumption. The present invention includes a mechanical vibration sensing means and a power sensing means to produce respective input signals which are processed by a signal processor and electronic computation means to produce an output a machining process condition signal. In the preferred embodiment the monitor is calibrated to produce a condition signal indicative of tool sharpness, excessive vibration, and loss of coolant as a function of the machines power consumption and mechanical vibrational levels as measured by the power and vibration sensing means respectively. The preferred embodiment of the present invention is illustrated in the form of a grinding wheel monitor but alternative embodiments contemplate other machining monitors which employ other material removal tools. The present invention includes an accelerometer mounted on the machine for a means to measure vibration. The present invention further contemplates the use of analog and digital signal processing and electronic computation means. ADVANTAGES The present invention provides a versatile non machine specific means for the detection of changing machining process parameters that affect product quality on any machining apparatus and is used to produce high quality parts. The illustrative example of the preferred embodiment of the invention provides that grinding process parameters taken into account include grinding wheel sharpness, vibrations, specific energy and coolant levels being used in the grinding process. The present invention may be used on various types of grinding machines such as cylindrical grinders, centerless grinders, surface grinders, creep feed grinders, tool grinders, etc. The present invention provides a means to detect the grinding wheel sharpness condition, a sudden loss of coolant, and excessive vibrations between the grinding wheel and the work piece during machining. The invention also takes into account machine operating parameters for the purpose of maximizing productivity and/or minimizing operating costs. The parameters provided for include wheel speeds, feeds, depth of grind, spark out, dressing cycle, and wheel hardness. BRIEF DESCRIPTION OF THE DRAWINGS The foregoing aspects and other features of the invention are explained in the following description, taken in connection with the accompanying drawings where: FIG. 1 is a diagrammatic illustration of a typical grinding machine employing a grinding wheel condition monitor in accordance with the present invention. FIG. 2 is a graphic illustration of calibration measurements and related functions calculated by the computing means of the grinding wheel condition monitor of FIG. 1 in accordance with the present invention. FIG. 3 is an illustration of the calibration control panel located within the grinding wheel condition monitor of FIG. 1 in accordance with the present invention. FIG. 4 is a diagrammatic illustration of the output panel located on the rear side of the grinding wheel condition monitor of FIG. 1 in accordance with the present invention. FIG. 5a is a schematic flow diagram illustrating the signal processing portion of the control system for the grinding wheel condition monitor in accordance with the present invention. FIG. 5b is a schematic flow diagram illustrating the control logic portion of the control system for the grinding wheel condition monitor in accordance with the present invention. DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 1, the preferred embodiment of the present invention is illustrated as a means for monitoring the grinding process of grinding machine 21. The means for monitoring the grinding process includes a monitor 34 which is connected via line 31 to a mechanical vibration sensing means illustrated as a conventional accelerometer 30 operable to send a mechanical vibration signal and a conventional power sensing means 32, such as the "Power Cell" available from Load Controls Incorporated, operable to send a power level signal via line 33 to monitor 34. Grinding wheel monitor 34 is depicted as monitoring a conventional grinding machine 21, which may be a Numerically Controlled (NC) machine, having a grinding wheel 12 powered by a motor (not shown) under the spindle bearing cover 24 and controlled by a machine controller 14 and a table 22 operable for mounting workpiece 18. Also shown is a grinding coolant applicator 16. Accelerometer 30 provides a vibration sensing means and, though shown attached to a spindle bearing housing 24, may be placed at another more advantageous position on the grinding machine. A general rule is to place the accelerometer as close to the rotating tool as possible. Power sensing means 32 may be attached and connected to a machine controller 14 and provides a means for detecting power consumption by the machining process of machine 21 and producing a signal indicative of that level of power. The power consumption measured in the case of a grinding wheel machining process is the amount of electrical power delivered to the motor turning the grinding wheel is measured. Contained within monitor 34 is a computing means, shown in FIGS. 5A and 5B, which monitors the signals from accelerometer 30 and power signal sensing means 32 and provides an condition signal having at least one output in the form of an array of green, yellow, and red warning lights respectively labeled G, Y, and R on a front panel 35 of monitor 34 and an audible alarm 46 to supplement red warning light R. The preferred embodiment also provides means for outputing these condition signals via jacks on a back panel 90 of monitor 34 as depicted in FIG. 4. Condition signal lights G, Y, and R on front panel 35 correspond to jacks 104, 106, and 108 respectively. Back panel 90 also provides a mounting means for a fuse 92 and vibration and power sensor inputs 94 and 96 respectively. This provides a means for connecting the monitor to a computer or other automated system which can be used to control the machining operation or process. Referring to FIG. 2, the present inventions provides an apparatus and means for monitoring the operating condition of a machining process and tool such as a grinding process and wheel as depicted in the illustrative embodiment described herein. A computing means, described in more detail later herein, located within monitor 34 monitors the machining process as a function of mechanical vibration and power consumption as measured by accelerometer 30 and power sensing means 32. The monitoring function, graphically depicted in FIG. 2, is preferably broken up into three zones RED, YELLOW, and GREEN, as indicated, as a function of vibrations indicated by the Y axis and power as indicated by the X axis. The red line having a slope R2 and a Y intercept R1 and the green line having a slope G2 and a Y intercept G1 defines the three operating regions shown in the graph, wherein Green represents good or acceptable operating conditions, Yellow indicates cautionary conditions wherein some degree of scrutiny or attention is required, and Red indicates a poor or unacceptable machining process condition that requires the machine be stopped because it is operating outside of acceptable boundaries of performance such as a dull tool, grinding wheel 12 in the illustrative embodiment, or something is wrong with the machine such as a broken tool or loss of coolant. The embodiment illustrated herein incorporates an analog solid state system but a digital system is also acceptable and for some applications may be more desirable. The computing means is illustrated in FIG. 3 by way of a calibration control panel 50 used to calibrate monitor 34 and a circuitry flow chart in FIGS. 5a and 5b which illustrates the means of processing the input signals from vibration sensor 30 and power sensor 32. The calibration means of monitor 34 is basically illustrated on calibration panel 50 and includes position step gain and variable gain switches to adjust signal gain for the computing circuitry illustrated in FIGS. 5a and 5b. The various gain switches for X1, X2, G1, G2, R1, R2 and X1/X2 are depicted on the control panel 50 in FIG. 3. Furthermore, time delay is built into the yellow light circuit and the red light circuit in order to prevent transient signals from prematurely setting off the red or green warning light. The switches have a zero to ten second delay and wherein a one second delay is preferred and has been found sufficient for the grinding wheel embodiment of the present invention. A multi-positioned switch 58 multiplexes the various parameter circuits which must be calibrated by adjusting their gain to a digital voltmeter 54. Voltmeter 54 is a digital type which is used to set the gain on various circuits X1, X2, G1, R1, G2 and R2 of the illustrated embodiment. Note that the gain for X1 and X2 incorporates two gain switches, step gain switches 62 and 66 respectively (two position switches having first and second positions equal to x1 and x10 respectively) and fine gain switches (pots) 64 and 68 respectively having a range of 1 to 10. Adjustments for G1, G2, R1, and R2 only require fine gain and incorporate similar types of fine gain switches 70, 72, 74, and 76 respectively. Having thus described the calibration means, the calibration of monitor 34 will be described. Starting with a freshly dressed grinding wheel 12, a workpiece 18 is mounted on table 22. Grinding wheel 12 is then sharpened by dressing it up and a light first power cut is taken through workpiece 18 with the multiplexor switch 58 set to the X1/X2 position. During this cut, the X1 set of gain control switches 62 and 64 are adjusted so that the reading on volt meter 54 is point eight zero (0.80). Having thus set the gain on X1/X2 the same light grinding pass with the sharpened grinding wheel 18 is made but wherein the multiplexing switch 58 is set first to X1 and then to X2 and the values for the X1 and X2 are noted as X1 L and X2 L respectively. The process is repeated for relatively for heavier horse power cut wherein the values are noted for X1 H and X2 H which refer to the setting of multiplexor switch 58 to X1 and X2 respectively for a high horse power cut. Note that the low horse power and high horse power cuts refer to a light and heavy or deep cut respectively. Parameters R1, R2, G1, and G2 are calculated from the following functional formulas or relationships. DELTA.sub.X1 =X1.sub.H -X1.sub.L DELTA.sub.X2 =X2.sub.H -X2.sub.L C=X1.sub.L -X2.sub.L *(DELTA.sub.X1 /DELTA.sub.X2) G2=1.2*(DELTA.sub.X1 /DELTA.sub.X2) G1=1.2*C R1=1.68*C R2=1.68*(DELTA.sub.X1 /DELTA.sub.X2) Having thus calculated the above parameters, the calibration continues by sequentially setting the multiplexor switch 58 to G1, G2, R1 and R2 settings respectively and adjusting the gain for each selection to their respective parametric values previously calculated using gain switches 70, 72, 74 and 76 on calibration panel 50 as shown in FIG. 3. With the gain thus set for the calculated parametric values, green and red signal time delay switches 80 and 82 respectively on calibration panel 50 must be set. Time delay switches 80 and 82 are provided with a time delay ranging from 0 to 10 seconds wherein for the grinding wheel embodiment a one second delay is preferred. The construction and operation of the preferred embodiment of the computing means may be best understood by referring to FIGS. 5a and 5b. Referring to FIGS. 5a and 5b, circuitry for invention's computing means is illustrated by way of a flow chart describing the elements and operation of the computing means. Accelerometer signal 94 is input from accelerometer 30 by way of line accelerometer signal line 31 (shown in FIG. 1) into accelerometer amplifier 124 from where it is sent through a first high pass filter 128 and a first low pass filter 130 to filter out noise. Accelerometer signal 94 is subsequently converted to an absolute value by RMS (root means square) converter 132. The RMS accelerometer signal is adjusted by a vibration signal gain control 134 and output as signal X1 to both a signal divider 138 and to an X1 output jack 98 located on back panel 90 as illustrated in FIG. 4. Power signal 96 is generally of a greater voltage than accelerometer signal 94 and is received from power sensor 32 in a partially conditioned form therefore, in the case of the preferred embodiment, it is sent to a second low pass filter 142 to filter out noise and then a power signal gain control 146 and output as signal X2 to both signal divider 138 and to an X2 output jack 106 located on back panel 90 in FIG. 4. Signal X1/X2 is calculated by signal divider 138 and output to output jack X1/X2 jack 102 on back panel 90 in FIG. 4. Signals X1, X2, and X1/X2 are also output to voltmeter 54 via multi-position rotary switch 58 in FIG. 3 for adjustment of gain control for the calibration operation as described previously herein. Referring to FIG. 5b, a schematic of the functional logic circuit of the preferred embodiment is illustrated in flow chart format depicting the reception of a signal X2 from the sensor signal processor circuit of FIG. 5a by a first multiplier 150. Simultaneously parameter G2 signal is generated by taking a base signal 154, generated by a power supply (not shown) of monitor 34, and biased by a G2 gain control 156 whose calibration is described further on herein. Signals G1, R2, and R1 are generated in the same manner from base signal 154 and their respective gain controls 158, 172, and 184. Signals G2 and X2 are multiplied by a first multiplier 150 to produce a signal G2*X2 is then summed with signal G1 by a first summer 162. Summer 162 calculates the function G1+G2*X2 for use by a first comparator 166. First comparator 166 receives signal X1 and compares it to the function G1+G2*X2 and if it determines X1 is less than G1+G2*X2 then an activation signal is sent to green output circuit 168 which initiates a green output 104 and turns on the green signal light marked G on the front panel of monitor 34 in FIG. 1. If comparator 166 determines that signal X1 is greater than or equal to G1+G2*X2 then a signal is sent to the second comparator 194 for later use in determining whether the yellow or red circuit should be initiated. Still referring to FIG. 5b, signals X2 and parametric signal R2, generated from base signal 154 by an R2 gain control 172 in the same manner as parameters G2 and G1 were, multiplied by a second multiplier 180 to produce functional signal R2*X2 which is then sent to a second summer 190. Second summer 190 also receives a parametric signal R1, generated from base signal 154 by an R1 gain control 184. Second summer 190 calculates the functional signal R1+R2*X2. Second comparator 194 takes signal X1 and signal R1+R2*X2 and calculates whether X1 is less than or equal to R1+R2*X2. If second comparator 194 determines X1 is less than or equal to signal R1+R2*X2 an activating signal is sent to yellow output circuit 198 for initiating yellow output 106 and yellow light Y on the front panel of monitor 34. If X1 is found to be greater than R1+R2*X2 by second comparator 194 then red output circuit 202 activated and red output 108 is initiated as well as red light marked R on the front panel of monitor 34. An audible alarm is also initiated by red output circuit 202 which is marked 46 in both functional logic circuit of FIG. 5b and on the front panel of monitor 34. The present invention contemplates the use of non-linear functions which may include higher order equations such as to the power of 2 and 3 and more complicated computing means and calibration means. A digital computer such as one contained in a machine controller or a personal computer may be used. While the preferred embodiment of our invention has been described fully in order to explain its principles, it is understood that various modifications or alterations may be made to the preferred embodiment without departing from the scope of the invention as set forth in the appended claims. For example it is contemplated that the present invention may also be used to monitor the tool conditions or sharpness in a variety of machining systems, particularly automated ones such as NC machines, such as turning machines, drills, lathes etc, wherein material removal processes such as drilling or turning are employed.

A machine tool monitor having a machine power sensor and a machine vibration sensor transmitting respective vibration and power signals to a controller which process the signals and monitors the machines operation to detect a change in the machine's processing parameters solely as a function of the power and vibration signals. The monitor indicates whether the condition of the tool and its associated machining operation warrants scrutiny or should be stopped for service. Besides visual and audible alarm signals the machining condition monitor can be integrated with an automatic control such as an NC controller or PC. In one embodiment a grinding machine monitor is provided with a power sensor and vibration sensor wherein the controller is adjusted to signal conditions associated with wheel sharpness, loss of coolant, and excessive vibrations.

[0001] This application is a utility application that claims priority to co-pending U.S. Provisional Patent Application entitled, “Mobility Billing and Tracking Application for Blackberry® Phones”, having Ser. No. 61/300,555, filed Feb. 2, 2010 which is entirely incorporated herein by reference. FIELD OF THE INVENTION [0002] The present invention discloses an application for billing clients, creating estimates, invoices and billing, entering expenses and tracking time on cellular phones, such as Blackberry® phones. This invention is especially useful for small business owners to organize and manage their finances and manage their time. BACKGROUND OF THE INVENTION [0003] The prompt billing of clients is essential to small businesses and they many times do not have the resources to timely bill clients for their services. Many of them do not have an internal bookkeeper that handles the billing process. Throughout the work week, small businesses may generate numerous estimates and invoices, but experience shows they struggle to recall these documents in mobile “on the go” environments. The intention for the development of the application is to create a financial tracking application for on the go users. [0004] The invention addresses areas where Small to Midsize Enterprises (SMEs) could benefit from receiving assistance in their day-to-day operations. The most popular areas requiring intervention are in receivables management and in client tracking and invoicing. Another area for enhancement was seen in the creation and delivery of estimates. Whereas internal/external bookkeepers or financial accountants mainly handle the procurement process in these companies, this action requires someone to stop to generate a paper document from a computer. Tracking billable hours and expenses spent on projects while being mobile was also challenging for SMEs. [0005] The method and system of this invention enable on the go SMEs to create and send billing via email/WAP to customers. Upon receipt of the client's bill, customers have the option to access invoices and select a payment option through a designed payment computer or a web services payment system. When the customer pays, the account balance is updated and shows up on the mobile device the next time the user logs in. [0006] Many times it is desirable to get a bill to a client as soon as the services are rendered. The likelihood of the client paying is higher the sooner the bill arrives. It is very important for small businesses to manage their time efficiently as they are frequently understaffed. It is especially important for the owner as his or her time is the most valuable of anyone in the business. The success or failure of the business is frequently dependent on the efficient time management of the owner. SUMMARY OF THE INVENTION [0007] Methods and systems with this invention provide the means to create customer information management that track billing and payment activity via a mobile device, such as a cellular smart phone. [0008] In an illustrative example, the mobile application is loaded on the user's mobile device. To access the application, the user logs into the system via a mobile device. The user will have following text fields to enter the information for accessing his/her Web Service account data: ‘Sub Domain’ [0009] ‘Sub Domain’ is derived from the Web Service's account URL (If the login page URL is ‘mycompany.WebService.com’ then subdomain is ‘mycompany’.) [0010] These fields can later be accessed and edited via Settings screen. The menu driven invention allows users to select from two very straightforward setup options. The initial set up of the invention will enable the user to have the flexibility to access their Account from the Internet web service or directly from their phone. From the set up menu, the user can set up the Client contacts. The method and system in this invention enables setting up their invoicing, estimate and time management templates. The Home Screen displays the following options to the user: [0000] 1. Clients: To navigate to the ‘Clients’ Screen 2. Invoices: To navigate to the ‘Invoices’ Screen 3. Estimates: To navigate to the ‘Estimates’ Screen 4. Expenses: To navigate to the ‘Expenses’ Screen 5. Time Entries: To navigate to the ‘Time Entries’ Screen 6. Expense Categories: To navigate to the ‘Expense Categories’ Screen For new clients, here is the Fields to be displayed on the screen: 1. Organization name 2. First name 3. Last name 4. Email (Mandatory field) 5. Billing Address: Street Addresses, City, Province/State, Postal/Zip, Country 6. Secondary Address: Street Addresses, City, Province/State, Postal/Zip, Country [0011] Save Button: If the server responds with success, the following message is displayed: “Your client has been created.” Import Contact: Open up the Contact list from the mobile device, which the user can select the desired contact to import. After selecting a contact the fields that exist in selected mobile device Contact (e.g. first name, last name, phone number etc.) will be filled up on the ‘New Client’ screen. For estimates, a list of the estimates that belong to the logged in user's client (if the user is a staff member) or all the clients (if the logged in user is an admin) can be seen on the screen when this option is selected. Staff can access the screen if the Estimates tab is enabled for staff. Each item in the list contains: 1. Organization Name 2. Estimate Number 3. Date of Issue 4. Amount due (in USD) [0012] 5. Status (invoiced, draft etc.) Estimates can be converted to invoices. Convert to Invoice: On selecting this menu item, user is presented with a new screen with the following two options: a) One time Invoice On selecting this option, the estimate is converted to one time in-voice application program interface (API call: invoice. Create) and added to Invoice tab of the In-voice screen. b) Recurring Invoice [0013] On selecting this option, the estimate is converted to recurring type invoice (API call: recurring. Create) and added to Recurring tab of the Invoice screen. Further, estimates can be edited by doing the following actions: Add item: Selecting Add Item, a user is taken to a new screen in which the user is required to enter Item name, description of item, unit cost, quantity, taxes Add Time entry: Selecting Add time entry, a user is taken to a new screen in which the user is required to enter time, entry notes, rate, hours, and taxes The web service updates upon receipt of edits and deletions by doing the following: [0016] Edit button: [0017] If the server responds with a success, the following message is displayed: “Your estimate has been updated.” [0000] Delete button: [0018] If the server responds with a success, the following message is displayed: “Estimate has been deleted.” [0019] The estimates list is updated. [0000] In the case of invoices there is a bar consisting of two tabs: Invoices (Selected by default): To display a list of all invoices Recurring: To display a list of all ‘Recurring’ type invoices Each item in the list (Invoices/Recurring) display following items: Organization name Invoice number Date of Invoice Amount due (in USD) Status (invoiced, draft etc.) (Staff has access to this screen if the Invoices tab is enabled for staff. Staff users can only access invoices that belong to clients they are assigned to. 1 Invoices like converted estimates carry out the same functions as expressed above. However, invoices have a filter feature that places each invoice in a category based on status. See below for a listing of invoice status types. Filter: Filter menu item has following sub menu items [0027] Disputed: sorts Invoices according to dispute status. [0028] Draft: sorts Invoices according to draft status [0029] Sent: sorts Invoices according to sent status [0030] Viewed: sorts invoices according to viewed status [0031] Paid: sorts invoices according to paid status [0032] Auto-Paid: sorts invoices according to auto-paid status [0033] Retry: sorts invoices according to retry status [0034] Failed: sorts invoices according to failed status [0035] Unpaid: sorts invoices according to unpaid status [0000] Once the invoice is created and saved, payments are categorized by invoice ID, and can be sorted by payment history. Payments can be sent to customers via email or WAP, and through the web service payment options, customers can pay directly. When payment is made, the web services account is updated and the new balance appears on the mobile device the next time the user logs in. On selecting enter payments, the user is taken to Enter Payment Screen having the following fields for the user to fill/select: a) Payment Amount b) Payment Method [0036] c) Date of payment d) Notes [0000] BRIEF DESCRIPTION OF DRAWINGS [0037] FIG. 1 is a drawing of the home page of a Blackberry® phone. [0038] FIG. 2 is a drawing of a Blackberry® phone showing an estimate on the screen. [0039] FIG. 3 is a drawing of a Blackberry® phone showing the invoice page on the screen. [0040] FIG. 4 is a drawing of Blackberry® phone showing the expense screen. [0041] FIG. 5 is a drawing of Blackberry® phone showing the time entry screen. [0042] FIG. 6 is the schematic diagram illustrating a system which keeps track of clients; creates invoices, estimates, time entry, expenses and other procurement activity via a mobile phone that communicates with a computer or web service. [0043] FIG. 7 is a schematic diagram illustrating the payment process and it's interrelationship with the computer or web. DETAILED DESCRIPTION OF THE INVENTION [0044] The mobility billing and tracking application (MBTA) of this invention provides an entire system for billing of clients, providing estimates of costs to clients, producing bills or invoices for clients, entering expenses, and keeping track of time of the owner and others working for the business. The MBTA will track financial information. The time management is synchronized with the phone's alarm clock function. [0000] The MBTA can also be adapted to be used with other phones than the Blackberry® operating systems and phones using the Windows 7 operating system, Palm Web OS, Android, I Phones, Nokia, and Symbian OS. The MBTA is especially designed for the Blackberry® phone. [0045] The software for the billing and tracking system application of this invention can be downloaded from the web into a Blackberry® phone or another smart cellular phone. This website will need security in order to protect the unauthorized downloading of this application into a smart phone. The wireless phone will also have a log in and password in order to prevent access to this billing and tracking application by unauthorized users. [0000] FIG. 1 is a drawing of a Blackberry phone showing the four main functions that the billing and tracking system can perform. These functions are creating invoices and estimates, billing and listing expenses and putting in time entries. [0046] Once the billing and tracking application has been downloaded into a smart cellular phone, such as a Blackberry®, an invoice can be created by the user of the phone by simply typing the invoice on the Blackberry®. In the case of an invoice, the invoice can be sent by email to a client or the invoice can be shown to the client from the screen of the Blackberry®. The invoice can be transmitted to the central computer which can then generate a physical invoice or send the invoice by PDF or other means to the client. The invoice and other documents created on the smart phone will be stored in the computer. The invoice of course can be managed and changed by the central computer before it is actually sent to the client. It could also be changed by the user of the Blackberry® upon showing the invoice to the client on the screen of the Blackberry® or sending by email to the client. [0047] It is important to realize that the smart phone such as the Blackberry® is connected to a central computer where all of the information is stored. [0048] The smart phone utilizes the native clock of the phone for keeping track of time which may be one of the ways in which the amount of the invoice or time is determined. Other items such as supplies, etc. can be entered on the invoice and the smart phone. It is extremely important that the invoice be integrated with the smart phones. [0049] Preferably the storage in the computer will be done in files such as a file for invoices and a file for estimates and other items that the billing and tracking application is capable of handling. The invoice of course can be managed and changed by the central computer before it is actually sent to the client. It could also be changed by the user of the Blackberry upon showing the invoice to the client on the screen of the Blackberry® or sending by email to the client. [0050] Other items such as supplies, etc. can be entered on the invoice and the smart phone. It is extremely important that the invoice be integrated with the smart phones user's accounting system. [0051] Payment can be entered into the system to change the balance of the accounts receivable. [0052] FIG. 2 shows the estimate screen for a Blackberry®. The estimate can be created by the user of the phone by typing in the estimate. The calculator on the phone can be used to make any computations that are necessary. This estimate can be sent to the client by email or the screen can be shown to the client if the estimate is made in the presence of the client. This estimate is sent to the central computer and stored, preferably in a file of estimates. This application will produce new estimates or revise old estimates that have been given previously to the client. The estimate can be saved in the memory on the phone and later saved on the central computer or sent to the central computer at the same time the estimate is created on the phone. [0053] FIG. 3 shows the screen of a Blackberry® with a sample invoice. The Blackberry® can store the necessary information on the client and the invoice numbers and the invoice can be typed in by the user of the Blackberry® or other smart phones. This invoice can be sent by email to the client and also sent to the central computer. The invoice can be stored on the Blackberry®. The invoice can be sent to the client by email or from the computer by PDF or other means. [0054] One of the major problems of a smart phone user who travels is keeping track of expenses. FIG. 4 shows a screen of expenses where various expenses can be entered into the Blackberry® and conveyed back to the central computer. This expense screen can be entered at the time the expense is incurred so it is not necessary to create a separate expense report. The client name or client number can be entered on the expense report so that a written report can be automatically generated by the central computer. [0055] Many professionals bill upon the time spent. FIG. 5 allows the time to be entered. This utilizes the native clock in the phone. The name of the client or the client number can be entered in connection with the time. This information can be conveyed back to the central computer and used to generate an invoice based upon the time of a phone call on the smart phone. This can be entered and also list the client information. [0056] This application will also allow the user of the phone to enter a payment by credit card or cash by entering it into the smart phone which will be conveyed back to the computer. The credit card information can be entered into the phone and will be protected by the security features of the phone for this application. [0057] It is important to keep in mind that the central computer is an important part of this application and that it can reconcile invoices and also point out inconsistencies between information entered in the smart phone and present in the computer. A cash payment made to the user by a client can also be entered in the smart phone and an email receipt sent by the phone to the client or from the computer. [0058] For purposes of security of this application, it may have a separate login and password than that from the phone itself. [0059] The data that is entered in the smart phone can be placed on the web which is protected by security for viewing by the client. APPLICATION TECHNICAL DESIGN [0060] The design of the application is set forth below: MBTA Blackberry Application Technical Design Screens: 1.1 Login Screen [0061] This screen will be displayed only once for the first time entry into the application. It will have following text field for a user to enter the information for accessing his/her account data: ‘Sub Domain’ ‘Sub Domain’ is derived from the account URL (If the login page URL is ‘mycompany.com’ then subdomain is ‘mycompany’.) This field can later be accessed and edited via Settings screen. Buttons: [0063] ‘Let's Go’: Clicking this button, will use the token for basic HTTP authentication and will store this information in the applications internal database. 1.2 Home Screen [0064] This screen will display the following options to the user: [0065] 1. Clients: To navigate to the ‘Clients’ Screen [0066] 2. Invoices: To navigate to the ‘Invoices’ Screen [0067] 3. Estimates: To navigate to the ‘Estimates’ Screen [0068] 4. Expenses: To navigate to the ‘Expenses’ Screen [0069] 5. Time Entries: To navigate to the ‘Time Entries’ Screen [0070] 6. Expense Categories: To navigate to the ‘Expense Categories’ Screen 1.3 Clients Screen [0071] Fields to be displayed on the screen: A list of the clients that are already added for the logged in users company Each item in the list contains: a) Client's Name b) Client's Organization Name List Item Click Event: [0072] Navigate to: ‘Client's Details’ screen. [0000] Menu Items and their Click Events: Home: [0073] Navigate to: ‘Home’ Screen New Client: [0074] Navigate to: ‘New Client’ Screen 1.3.1 Client's Details Screen [0075] Fields to be displayed on the screen: [0076] 1. Organization name [0077] 2. Name [0078] 3. Email [0079] 4. Billing Address: Street Addresses, City, Province/State, Postal/Zip, Country [0080] 5. Contact numbers: Work Contact no., Home Contact no., Fax no. [0081] 6. Credit Information—This is only required for clients with recurrent billing. This information is optional [0000] Menu Items and their Click Events: Home: [0082] Navigate to: ‘Home’ Screen Edit Client: [0083] Navigate to: ‘Edit Client’ Screen 1.3.2 New Client Screen [0084] Fields to be displayed on the screen: [0085] 1. Organization name [0086] 2. First name [0087] 3. Last name [0088] 4. Email (Mandatory field) [0089] 5. Billing Address: Street Addresses, City, Province/State, Postal/Zip, Country [0090] 6. Secondary Address: Street Addresses, City, Province/State, Postal/Zip, Country [0000] Save Button: If the server responds with success, the following message is displayed: [0091] “Your client has been created.” [0000] Menu Items and their Click Events Home: Navigate to: ‘Home’ Screen [0092] Import Contact : Open up Blackberry Contact list from which the user can select the desired contact to import. After selecting a contact the fields that exist in selected Blackberry® Contact (e.g. first name, last name, phone number etc.) will be filled up on the ‘New Client’ screen. 1.3.3 Edit Client Screen [0093] Fields to be displayed on the screen: [0094] 1. Organization name [0095] 2. First name [0096] 3. Last name [0097] 4. Email [0098] 5. Billing Address: Street Addresses, City, Province/State, Postal/Zip, Country [0099] 6. Secondary Address: Street Addresses, City, Province/State, Postal/Zip, Country Notes Buttons: Edit Button: [0100] if the server responds with a success, following message is displayed “Your client has been updated.” Delete Button: [0101] If the server responds with a success, the following message is displayed “Your client has been deleted.” [0000] Menu Items and their Click Events: Home Navigate to: ‘Home’ Screen 1.4 Estimates Screen [0102] Fields to be displayed on the screen: A list of the estimates that belong to the logged in user's client (if the user is a staff member) or all the clients (if the logged in user is an administrator). Staff can access the screen if the Estimates tab is enabled for staff. Each item in the list contains: [0103] 1. Organization Name [0104] 2. Estimate Number [0105] 3. Date of Issue [0106] 4. Amount due (in USD) [0107] 5. Status (invoiced, draft etc.) List Item Click Event: [0108] Navigate to: ‘Estimate Details’ screen. [0000] Menu Items and their Click Events: Home Navigate to: ‘Home’ Screen 1.4.1 Estimate Detail Screen [0109] Fields to be displayed on the screen: [0110] 1. Estimate number [0111] 2. Estimate status (sent, invoiced, partial etc.) [0112] 3. Client's Address: Organization name, Street addresses, City, Province/state, Postal/zip, Country [0113] 4. Table with following data fields: Item Description Cost Quantity Total [0119] 5. Subtotal [0120] 6. Taxes applied [0121] 7. Total [0122] 8. Amount Paid [0123] 9. Balance due (in USD) [0124] 10. Terms [0125] 11. Notes [0000] Menu Items and their Click Events: Home [0126] Navigate to: ‘Home’ screen Convert to Invoice: [0127] On selecting this menu item, user is presented with a new screen with the following two options: [0128] a) One time Invoice On selecting this option, the estimate is converted to one time invoice (Application Program Interface, API call: invoice. Create) and added to Invoice tab of the Invoice screen. [0130] b) Recurring Invoice [0131] On selecting this option, the estimate is converted to recurring type invoice (API call: recurring. Create) and added to Recurring tab of the Invoice screen. Edit Estimate: [0132] Navigate to: ‘Edit Estimate’ screen 1.4.2 Edit Estimate Screen [0133] Fields to be displayed on the screen: [0134] 1. Organization: Drop down menu consisting of all organizations [0135] 2. Address: Address corresponding to selected organization [0136] 3. Estimates Details: Estimate number, Date of issue, PO number, Discount % [0137] 4. Dropdown list consists of following items: Add item: Selecting Add Item, a user is taken to a new screen in which the user is required to enter Item name, description of item, unit cost, quantity, taxes Add Time entry: Selecting Add time entry, a user is taken to a new screen in which the user is required enter time entry notes, rate, hours, and taxes [0140] On returning from new screen, the new item/time entry is added to Edit Estimate Screen. [0141] 5. Subtotal [0142] 6. Total [0143] 7. Amount Paid [0144] 8. Balance due [0145] 9. Terms [0146] 10. Notes Buttons: [0147] Edit button: [0148] If the server responds with a success, the following message is displayed: “Your estimate has been updated.” [0000] Delete button: [0149] If the server responds with a success, the following message is displayed: “Estimate has been deleted.” [0150] The estimates list is updated. [0000] Menu Items and their Click Events: Home [0151] Navigate to: ‘Home’ screen 1.5 Invoices Screen [0152] Fields to be displayed on the screen: [0153] 1. A tab bar consisting of two tabs: Invoices(Selected by default): To display a list of all invoices Recurring: To display a list of all ‘Recurring’ type invoices [0156] Each item in the list (Invoices/Recurring) display following items: Organization name Invoice number Date of Invoice Amount due (in USD) Status (invoiced, draft etc.) (Staff has access to this screen if the Invoices tab is enabled for staff. Staff users can only access invoices that belong to clients they are assigned to.) List Item Click Event: [0162] Navigate to ‘Invoice Details’ screen [0000] Menu Items and their Click Events: 1) Home: [0163] Navigate to: ‘Home’ Screen [0164] Menu items 2, 3 are presented only if the ‘Invoice’ tab is selected. 2) New Invoice Navigate to: ‘New Invoice’ Screen [0165] 3) Filter: Filter menu item has following sub menu items [0166] Disputed: sorts Invoices according to dispute status. [0167] Draft: sorts Invoices according to draft status [0168] Sent: sorts Invoices according to sent status [0169] Viewed: sorts invoices according to viewed status [0170] Paid: sorts invoices according to paid status [0171] Auto-Paid: sorts invoices according to auto-paid status [0172] Retry: sorts invoices according to retry status [0173] Failed: sorts invoices according to failed status [0174] Unpaid: sorts invoices according to unpaid status 1.5.1 Invoice Details Screen [0175] Fields to be displayed on the screen: [0176] 1. Invoice number [0177] 2. Invoice status (sent, draft, disputed, viewed) [0178] 3. Address: Organization name, Street addresses, city, province/state, postal/zip, country [0179] 4. Table with the following data fields: Item Cost Quantity Total [0184] 5. Subtotal [0185] 6. Taxes applied [0186] 7. Total [0187] 8. Amount Paid [0188] 9. Balance due (in USD) [0189] 10. Menu Items and their Click Events: 1) Home: [0190] Navigate to: ‘Home’ Screen 2) Edit Invoice [0191] Navigate to: ‘Edit Invoice’ Screen 3) Send Invoice: [0192] Send Invoice menu item has three sub menu items: [0193] 1) Via Email: [0194] 2) Via e-Fax: [0195] 3) Via snail mail: [0196] 4) 4) View Payment History: Shows all the payments related to this particular invoice id. 1.5.2 New Invoice Screen [0197] Fields to be displayed on the screen: [0198] 1. Organization: Drop down menu consisting of all organizations (Mandatory field) [0199] 2. Address: Address corresponding to selected organization. [0200] 3. Invoice Details: Invoice number, Date of Issue, PO number, Discount % [0201] 4. Label with text “The Client has outstanding expenses” and an ‘Add to Invoice’ button if the Client has outstanding expenses. On pressing ‘Add to Invoice’ button the outstanding expense is added as a line entry to invoice. [0203] 5. Drop down list consists of following items: Add item: On selecting Add Item user is taken to new screen in which user is required to enter Item name, description of item, unit cost, quantity, taxes Add Time entry: On selecting Add time entry user is taken to new screen in which user is required enter time entry notes, rate, hours, and taxes On returning from new screen, the new item/time entry created is added to [0207] New Invoice Screen. [0208] 6. Subtotal [0209] 7. Total [0210] 8. Amount Paid [0211] 9. Balance due [0212] 10. Terms [0213] 11. Notes: User can enter notes(not visible to client) Buttons: [0214] Done button: If the server responds with a success, the following message is displayed: “Your invoice has been created” Menu Items and their Click Events: Home: [0215] Navigate to: ‘Home’ Screen View Payment History: [0216] Shows all the payments related to this particular invoice id. 1.5.3 Edit Invoice Screen [0217] Fields to be displayed on the screen: [0218] 1. Organization: Drop down menu consisting of all organizations. [0219] 2. Address: Address corresponding to selected organization. [0220] 3. Invoice Details: Estimate number, Date of Issue, PO number, Discount % [0221] 4. Drop down list consists of following items: Add item: On selecting Add Item user is taken to new screen in which user is required to enter item name, description of item, unit cost, quantity, taxes Add Time entry: On selecting Add time entry user is taken to new screen in which user is required enter time entry notes, rate, hours, and taxes On returning from the new screen, the new item/time entry created is added to Edit Invoice Screen. [0225] 5. Subtotal [0226] 6. Total [0227] 7. Amount Paid [0228] 8. Balance due [0229] 9. Terms [0230] 10. Notes Buttons: [0231] Edit button: “Your invoice has been updated” Delete button: Menu Items and their Click Events: Home Navigate to: ‘Home’ Screen Enter Payments [0000] On selecting enter payments, user is taken to Enter Payment Screen having the following fields for the user to fill/select: a) Payment Amount b) Payment Method c) Date of payment d) Notes View Payment History: Shows all the payments related to this particular invoice id. 1.6 Expenses Screen [0237] Fields to be displayed on the screen: A list of expenses with each item in the list displaying: Expense Category Date Amount (in USD) Status (unbilled, not assigned, invoiced) List item click event Navigate to: ‘Expense Detail’ screen Menu Items and their Click Events: Home: Navigate to: ‘Home’ Screen New Expense: Navigate to: ‘New Expense’ Screen 1.6.1 Expense Details Screen [0242] Fields to be displayed on the screen: [0243] 1. Amount [0244] 2. Date [0245] 3. Vendor [0246] 4. Category [0247] 5. Status (unbilled, not assigned, invoiced) [0248] 6. Taxes included [0000] Menu Items and their Click Events: Home: Navigate to: ‘Home’ Screen Edit Expense: Navigate to: ‘Edit Expense’ Screen 1.7.1 New Expense Screen [0249] Fields to be displayed on the screen: [0250] 1. Amount (Mandatory) [0251] 2. Date (Mandatory) [0252] 3. Vendor [0253] 4. Category (Mandatory) [0254] 5. Tax: Drop down list of existing taxes [0255] 6. Amount (after applying tax) [0256] 7. Assign to Client: Drop down list of existing Clients [0257] 8. Project: Drop down list of all the projects for the selected client [0258] 9. Notes [0000] Buttons: Add Expense button Menu Items and their Click Events: Home: Navigate to: ‘Home’ Screen [0259] Import from Calendar: User is shown a list of Calendar events, from which he can select any event to import as new expense. 1.6.2 Edit Expense Screen [0260] Fields to be displayed on the screen: [0261] 1. Amount (Mandatory) [0262] 2. Date (Mandatory) [0263] 3. Vendor [0264] 4. Category (Mandatory) [0265] 5. Tax: Drop down list of existing taxes [0266] 6. Amount (after applying tax) [0267] 7. Assign to Client: Drop down list of existing Clients [0268] 8. Project: Dropdown list of all projects of selected client [0269] 9. Notes Buttons: Edit Button: [0270] On pressing ‘Edit’ button a call is made to ‘expense. Required parameters can be obtained from Edit Expense Screen. Delete Button: [0271] On pressing ‘Delete’ button a call is made to ‘expense. Delete’. If the server responds with success, then selected expense is deleted and the expense list is updated accordingly. Following message is displayed on successful deletion: “Expense has been deleted” Menu Items and their Click Events: Home [0272] Navigate to: ‘Home’ Screen 1.7 Time Entries Screen [0273] Fields to be displayed on the screen: A list of expenses with each item in the list displaying: [0274] 1. Project (Mandatory) [0275] 2. Task (Mandatory) [0276] 3. Date (Mandatory) [0277] 4. Hours [0000] List item click event [0278] Navigate to: ‘Time Entry Detail’ screen [0000] Menu Items and their Click Events: Home [0279] Navigate to: ‘Home’ Screen New Time Entry [0280] Navigate to: ‘New Time Entry’ Screen 1.7.1 Time Entry Detail Screen [0281] 1. Fields to be displayed on the screen: [0282] 2. Project (Mandatory) [0283] 3. Task (Mandatory) [0284] 4. Date (Mandatory) [0285] 5. Hours [0286] 6. Notes [0000] Menu Items and their Click Events: Home [0287] Navigate to: ‘Home’ Screen Edit Time Entry [0288] Navigate to: ‘Edit Time Entry’ Screen 1.7.2 New Time Entry Screen [0289] Fields to be displayed on the screen: [0290] 1. Project: Drop down list consisting all existing project [0291] 2. Task: Drop down list consisting of existing tasks [0292] 3. Hours [0293] 4. Notes [0294] 5. Date Buttons: [0295] Create button Menu Items and their Click Events: Home: [0296] Navigate to: ‘Home’ Screen Edit Time Entry: [0297] Navigate to: ‘Edit Time Entry’ Screen [0000] Import from Calendar: [0298] User is shown a list of Calendar events from which user can select the events he wants to include in the Time entry. 1.7.3 Edit Time Entry Screen [0299] Fields to be displayed on the screen: [0300] 1. Project: Drop down list consisting all existing project [0301] 2. Task: Drop down list consisting of existing tasks [0302] 3. Hours [0303] 4. Notes [0304] 5. Date Button: [0305] Edit button: [0306] If the server responds with success, then an alert is shown displaying “Time Entry successfully updated”. [0000] Delete Button: If the server responds with success, then selected time entry is deleted and the time entries list is updated accordingly. [0307] Menu Items and their Click Events: Home Navigate to: ‘Home’ Screen 1.8 Expense Categories Screen [0308] Fields to be displayed on the screen: A list of expenses with each item in the list displaying: Category Name [0309] List item click event [0310] Navigate to: ‘Category Detail’ screen [0000] Menu Items and their Click Events: Home [0311] Navigate to: ‘Home’ Screen New Category [0312] Navigate to: New Category Screen 1.8.1 Category Detail Screen [0313] Fields to be displayed on the screen: Category Name [0314] Menu Items and their Click Events: Home [0315] Navigate to: ‘Home’ Screen Edit Category [0316] Navigate to: ‘Edit Category’ Screen 1.8.2 New Category Screen [0317] Fields to be displayed on the screen: Category Name Buttons: [0318] Menu Items and their Click Events: Home [0319] Navigate to: ‘Home’ Screen 1.8.3 Edit Category Screen [0320] Fields to be displayed on the screen: Category Name Buttons: [0321] Edit button Menu Items and their Click Events: Home [0322] Navigate to: ‘Home’ Screen 1.9 Offline Backup [0323] On unavailability of network, all the new invoices, estimates and time entries created will be temporarily stored to a persistent storage of the device. All data updates can be done off-line and synchronized later when the network is available. 1.10 SetUp Screen [0324] The following options will be included on the Settings screen. These will be editable by the user at any time [0325] 1. Subdomain [0326] 2. Authorization [0327] 3. Refresh on open (Yes/No)—whether application should refresh entries from the server after user re-enters the application [0328] 4. Service request timeout (in seconds) [0329] 5. Request page size (0 by default)—number of pages to fetch for a request [0330] 6. Client display by (Org, Contact name) [0331] 7. Default currency (default USD) [0332] 8. e-fax login [0333] 9. Tax Settings (maximum 4)—For each tax, the following will be input from the user a. Tax name b. Tax percent c. Government tax ID (optional) FEATURES OF THE INVENTION [0337] The invention contains many features including: Output of the billing invoice, estimate etc. is in the form of an Adobe PDF., or a Comma Delimited File.csv Upon completion of the template edit (Estimate, Invoice or Time Mgmt.), the user will have the option to save the file created as a PDF or as a Comma Delimited file (usually used to import into other applications) Payment processing: application keeps track of payments made by clients. When the client logs into the online portal (or if they have mobile account), he/she will be able to see and select payment options. The system flags payments that have been made on customer accounts and also deducts from existing balances. This enables the development of additional invoices. Synching phone's alarm clock with the Time Entry Users can keep track of their billable hours, and employers can keep track of time sheets from their employees who have been added to the system Conversion of Estimates to instant Invoices for billing The Invoice feature allows for instant conversion of saved Estimates. This feature will request if the Estimate requires Time Entry and if so, the system will apply start and completion times to projects (where applicable). Invoice sending features (via email or upload to online application) Saved invoices (PDF or CSV files) can be saved and sent to clients via: Email: Users can send emails or messages with file attachments directly from their phones File Upload: This process will require customers to Login to their online account from their phone, and upload files online Easy renewal process Multiple license purchase also available during download and installation process One touch Application upgrades Additional application features will be available and sent via email or text message to existing users. In compliance with current day online/mobile payment processing Clients will be able to use their current payment method and access the web service processing systems to receive and provide payment When the user sends out billing to clients, they have the option to pay using their existing payment provider During upgrade and application renewal, the customer can use their existing payment provider Some of the most relevant mobile device features that will interact with this invention are: Address book Alarm Calendar App [0364] Some of the specifications for this system are listed below: Programming Languages & Platforms Java Virtual Machine Sun Java FX Phone Edition Flash Scripting Adobe Flash SDK Flash Lite Web Application HTML/CSS HTML/CSS JavaScript (or AJAX) Php Python GPRS EDGE 3G UMTS Wi-Fi Mobile Standards Open Mobile Alliance (OMA) Open Mobile Terminal Platform (OMTP) Synchronization for telephony, mobile video, etc. (SyncML) GSM CDMA WiMAX

A billing and tracking application is provided for adding new clients, billing clients, creating estimates, tracking time, creating invoices, entering expenses and payments on smart cellular phones such as a Blackberry® phone. The phone in which this application is installed and the computer to which the information is sent is also disclosed. This allows a user to organize and manage their finances and manage their time away from the office.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame-retardant polypropylene resin composition having polypropylene resin as a main component, and more particularly, to a polypropylene resin composition which includes a polypropylene resin with a melt flow rate of 4-18 g/10 minutes, a halogen-containing flame retardant additive with a low melting point, an antimony oxide, an ultraviolet stabilizer, a silane coupling agent, and titanium dioxide used as a light-blocking agent. The resin composition exhibits good weathering properties and maintains the same level of flame retardancy as well as other physical/mechanical property characteristics after a hydrothermal dipping treatment. 2. Description of the Related Art Polypropylene resins are used extensively in home electronic appliances, building members, interior decorating materials, and automobile parts due to their excellent processing characteristics, chemical resistance, and mechanical strength. These resins, however, lack flame retardancy and are therefore difficult to use in the manufacture of automobile parts or electronic components which require protection against the danger of fire. As a result, the effects of the addition of various organic, inorganic, and phosphorus flame retardant additives on flame retardancy in polyolefin resins have been studied extensively. Japanese Patent Publication Nos. 53-92855, 54-29350, 54-77658, 56-26954, 57-87462, and 60-110738 disclose preparation methods of producing flame retardant polypropylene resin compositions by adding inorganic flame retardant additives such as magnesium hydroxide, aluminum hydroxide, or hydrotalcite. However, in order to obtain a flame retardant grade of V-0, a resin composition including more than 50% by weight of the inorganic filler is needed. This high level of inorganic filler results in a deterioration of the processability of the resin, generation of gas during processing, and a decrease in impact strength of the resin product. Japanese Patent Publication No. 53-30739 discloses flame retardant polypropylene resin compositions produced by adding organic halogen-containing flame retardant additives such as decabromodiphenylether and dodecachloro-dodecahydromethanodibenzocyclooctane. Other flame retardant polypropylene resin compositions are produced by adding tetrabromobisphenol A bis-(dibromopropylether), bis-(tribromophenoxyethyl)tetrabromobisphenol A ether, hexabromo cyclododecane, and tetrabromobisphenol A. Although these resin compositions exhibit excellent flame retardancy and processability, weatherability and resistance to hot water are poor making it difficult to use the resin in outdoor products such as light bulb sockets for Christmas tree lights. SUMMARY OF THE INVENTION The object of the invention is to solve the problems described above and to provide a flame-retardant polypropylene resin composition that exhibits good flame retardancy for thin-walled structures, produces products that maintain good flame retardancy even after long outdoor exposure times or hydrothermal dipping treatments, and exhibit good weather resistance while maintaining the mechanical properties of the resin. The flame-retardant polypropylene resin composition of the present invention includes about 40-90% by weight polypropylene resin with a melt flow rate of about 4-18 g/10 minutes, about 9-16% by weight halogen-containing flame retardant additive with a low melt point, about 4-15% by weight antimony oxide in the form of white granules, about 0.2-3.0% by weight ultraviolet stabilizer, about 0.1-5% by weight silane coupling agent, and about 0.2-5% by weight titanium dioxide. In the flame-retardant polypropylene resin composition of the present invention, the polypropylene resin may be a crystalline polypropylene homopolymer or a polypropylene copolymer of propylene with comonomers including ethylene, 1-butene, 1-pentene, 1-hexene, 4-methylpentene, 1-heptene, 1-octene, 1-decene, or mixtures thereof. The preferred polypropylene resin is a crystalline polypropylene homopolymer. The melt flow rate of the polypropylene resin may be about 4-18 g/10 minutes, or more preferably about 5-15 g/10 minutes. The amount of polypropylene resin in the overall resin composition may be 40-86% by weight, or more preferably, 50-86% by weight. In the flame-retardant polypropylene resin composition of the present invention, the halogen-containing flame retardant additive with a low melt point may be tetrabromobisphenol A bis-(dibromopropylether), tetrabromo dimethylsulfone dipropylether, or mixtures thereof. Examples of commercially available products include PE-68 (manufactured by Great Lakes Corporation) and P680G (manufactured by Suzuhiro Chemicals, Co.). A preferred amount of tetrabromobisphenol A bis-(dibromopropylether) or tetrabromodimethylsulfone dipropylether in the resin composition is about 9-16% by weight based on the overall weight of the resin composition. When the amount of flame retardant additive is below about 9% by weight, a flame retardancy grade of V-0 cannot be obtained for a film thickness of 1/32 inch. When the amount of flame retardant additive is above about 16% by weight, weather resistance is reduced making it difficult to maintain the mechanical properties of the resin. The silane coupling agent in the flame-retardant polypropylene resin composition of the present invention may be represented by the following general formula:  RR′SiX 2 where R is a hydrocarbon including vinyl, chloro, amino, and mercapto; X is an organic group that can be hydrolyzed; and R′ may be R or X. Examples of the silane coupling agent include vinyl trimethoxy silane, vinyl triethoxy silane, 3-aminopropyl triethoxy silane, N-(2-aminoethyl)-3-aminopropyltrimethoxy silane, 3-glycydoxypropyl trimethoxy silane, 3-chloropropyl trimethoxy silane, 3-methacryloxypropyl trimethoxy silane, and 3-mercaptopropyltrimethoxy silane. To improve dispersive strength and adhesive strength when using antimony trioxide and halogen-containing flame retardant additives, preferred silane coupling agents include vinyl trimethoxy silane, vinyl triethoxy silane, and 3-mercaptopropyltrimethoxy silane. The amount of silane coupling agent used in the resin composition may be about 0.1-5% by weight, preferably about 0.15-3% by weight, and more preferably about 0.3-1% by weight based on the weight of the overall resin composition. When the amount of silane coupling agent in the resin composition is below about 0.1% by weight, the dispersive strength and adhesive strength of the resin are not improved with the use of antimony trioxide or halogen-containing flame retardant additives. In addition, blooming of the flame retardant additive during dipping in a hydrothermal test cannot be prevented making it difficult to maintain a flame retardancy grade of V-0 for a film thickness of 1/32 inch. When the silane coupling agent amount is increased to levels of above about 5% by weight, there is no further improvement in the prevention of blooming of the flame retardant additive. In the flame-retardant polypropylene resin composition of the present invention, it is preferable to use UV absorbers and HALS stabilizers simultaneously as ultraviolet stabilizers. The preferred HALS stabilizer has a molecular weight of more than about 2,000. If the molecular weight of the HALS stabilizer is below about 2,000, ultraviolet stabilizers easily bloom out of the secondary product making it difficult to maintain long-term ultraviolet stability. The UV absorber and HALS ultraviolet stabilizer are preferably used in the resin composition in amounts of about 0.1-1.5% by weight each. If the UV absorber or HALS ultraviolet stabilizer is used alone in the resin composition, a flame retardancy grade of V-0 may be obtained; however, it may be difficult to produce a resin composition which meets the F1 standard for tensile impact strength after UV exposure treatment. In the flame-retardant polypropylene resin composition of the present invention, titanium dioxide is used as a light-blocking agent in order to obtain a grade of F1 for environmental resistance. The preferred amount of titanium dioxide is about 0.2-5% by weight. If the amount of titanium dioxide in the resin composition is below about 0.2% by weight, synergistic effects with the ultraviolet stabilizer are absent. Above amounts of about 5% by weight, there is no further improvement in light blocking ability. In the flame-retardant polypropylene resin composition of the present invention, antimony trioxide, antimony pentaoxide, or mixtures thereof may be used as the antimony oxide component. The antimony oxide may used in an amount of about 4-15% by weight and preferably about 5-12% by weight based on the weight of the overall resin composition. The flame-retardant polypropylene resin composition of the present invention exhibits excellent flame retardancy providing a grade of V-0 for a film thickness of 1/32 inch in the vertical burning test (hereinafter referred to as “UL 94 vertical burning test”) carried out as described in “Flammability Test of Plastic Materials for Parts of Mechanical device” of UL Subject 94. In addition, the resin composition not only maintains its mechanical properties but maintains the same grade of flame retardancy after long outdoor exposure times and hydrothermal dipping treatments as indicated by weathering and water resistance testing (hereinafter referred to as “UL 746C weather proof test”) carried out as described in “Test for Flammability of Plastic Materials for Parts in Electric Device” of UL subject 746C. Therefore, the resin composition of the present invention can be used in the production of electric appliances, building members, interior or exterior decorating materials, and automotive parts. The present invention will be further described in detail with reference to the examples and comparative examples as described below. The examples, however, are for the purpose of illustration and are not intended to limit the scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS EXAMPLE 1 The following components were added into a Hensel mixer and mixed by stirring for 3 minutes: 7.9 kg crystalline polypropylene homopolymer with a melt flow rate of 8 g/10 minutes as the polypropylene resin component, 1.4 kg tetrabromobisphenol A bis-(dibromopropylether) (PE-68 produced by Great Lakes Corporation), 700 g antimony trioxide (Sb 2 O 3 produced by Cheil Flame Retardant, Ltd., 1.2 μm), and as additives, 10 g calcium stearate, 10 g antioxidant (1010 Produced by CIBA GEIGY), 20 g IRGAFOS 168 (produced by CIBA GEIGY), 30 g UV absorber (Tinuvin 326 produced by CIBA GEIGY), 30 g HALS ultraviolet stabilizer (Chimabsorber 944FD produced by CIBA GEIGY), 200 g light-blocking agent TiO 2 (R-103 produced by Dupont, Inc.), and 70 g silane coupling agent (A-174 produced by Union carbide). The mixture was extruded at 190° C. in the form of pellets using a two-axis stirring extruder with a diameter of 30 mm. The extruded pellets were dried for three hours at 100° C. Flame retardancy test pieces were formed using an injection-molding machine with a maximum cylinder temperature fixed at 200° C. Flame retardancy and physical/mechanical properties of the test pieces were then determined. Results are shown in Table 1. Method of Treatment The test pieces were UV treated using ASTM 2565 Type A under weathering conditions as described in “Tests for Flammability of Plastic Materials for Parts in Electrical device” of UL 746C (Underwriter's Laboratories Incorporation) (UV irradiation quantity: 0.35 W/m 2 at 340 nm, black board temperature: 63° C., water spray method). The test pieces were dipped in a hydrothermal tank at a temperature of 70° C. and maintained for 7 days. Flame retardancy and physical/mechanical properties of the test pieces were then determined. Method of Evaluation Flame retardancy was evaluated using vertical burning tests as described in “Tests for Flammability of Plastic Materials for Parts in Mechanical device” of UL 94 (Underwriters Laboratories, Inc.). The thickness of each test piece was 1/32 inch. The tensile impact strength and maintenance rate were evaluated using the impact strength test standard ASTM D-1822. The measuring instrument was produced by TOYOSEIKI and used an S-type sample with a thickness of ⅛ inch. EXAMPLE 2 AND COMPARATIVE EXAMPLES 1-3 The pellets were prepared in the same way as described in Example 1 except that the amount of light-blocking agent, R-103, was modified as shown in Table 1. The extruded pellets were molded using an injection-molding machine to provide test pieces for determining flame retardancy and tensile impact strength. The flame retardancy and physical/mechanical properties were then determined. Results are shown in Table 1. A comparison of the results of Examples 1-2 and the results of Comparative examples 1-3, as presented in Table 1, shows that when appropriate amounts of TiO 2 are added as a light-blocking agent, a synergistic effect with the UV absorber and HALS ultraviolet stabilizer occurs. The synergy makes it possible to maintain a high tensile impact strength as well as a flame retardancy grade of V-0 after UV exposure. Flame retardancy and tensile impact strength, as well as weatherability, are also maintained after a hydrothermal dipping treatment providing a UL 764C grade of F1 for indoor and outdoor electrical devices. EXAMPLES 3-4 AND COMPARATIVE EXAMPLES 4-5 The pellets were prepared in the same way as described in Example 1 except that the amount of antimony trioxide used as a flame retardant additive was modified as shown in Table 1. The extruded pellets were molded using an injection-molding machine to provide test pieces for determining flame retardancy and tensile impact strength. Flame retardancy and physical/mechanical properties were then determined. Results are shown in Table 1. A comparison of the results of Examples 3-4 with the results of Comparative examples 4-5, as presented in Table 1, shows that the amount of flame retardant additive in the composition should be below a certain level in order to promote synergy between the flame retardant and the UV absorber and stabilizers. The flame retardant should be maintained below a given amount in the composition in order to maintain flame retardancy after UV exposure testing and hydrothermal dipping treatments as well. When antimony trioxides are added in excess of about 17%, the physical/mechanical properties are degraded and no further synergistic effects with flame retardancy are exhibited thereby preventing a UL 764C grade of F1. EXAMPLE 5 The following components were added into a Hensel mixer and mixed by stirring for 3 minutes: 7.9 kg crystalline polypropylene homopolymer with a melt flow rate of 4 g/10 minutes as the polypropylene resin component, 1.4 kg tetrabromobisphenol A bis-(dibromopropylether) (PE-68 produced by Great Lakes Corporation), 700 g antimony trioxide (Sb 2 O 3 produced by Cheil Flame Retardant, Ltd., 1.2 μm), and as additives, 10 g calcium stearate, 10 g antioxidant (1010 Produced by CIBA GEIGY), 20 g IRGAFOS 168 (produced by CIBA GEIGY), 30 g UV absorbent (Tinuvin 326 produced by CIBA GEIGY), 30 g HALS ultraviolet stabilizer (Chimabsorber 944FD produced by CIBA GEIGY), 200 g light-blocking agent TiO 2 (R-103 produced by Dupont, Inc.), and 70 g of silane coupling agent (A-174 produced by Union carbide). The mixture was extruded at 190° C. in the form of pellets using a two-axis stirring extruder with a diameter of 30 mm. The extruded pellets were dried for three hours at 100° C. Flame retardancy test pieces were formed using an injection-molding machine with a maximum cylinder temperature fixed at 200° C. Flame retardancy and physical/mechanical properties of the test pieces were then determined. The methods of treatment and evaluation were the same as described in Example 1. Results are presented in Table 1. EXAMPLE 6 AND COMPARATIVE EXAMPLES 6-7 The pellets were prepared in the same way as described in Example 1 except that the polypropylene resin was changed to a polypropylene resin with a different melt flow rate as shown in Table 1. The extruded pellets were molded using an injection-molding machine to provide test pieces for determining flame retardancy and tensile impact strength. Flame retardancy and physical/mechanical properties were then determined. Results are shown in Table 1. As seen in Table 1, the melt flow rate of the polypropylene resin has a large effect on the properties of the composition as shown by the results of the UV exposure testing and hydrothermal dipping treatments. If the melt flow rate of the polypropylene resin is less than about 4 g/10 minitues, the initial properties are excellent; however, after UV exposure testing, the physical/mechanical properties are degraded. If the melt flow rate is above 20 g/10 minitues, the initial flame retardancy and the flame retardancy after UV exposure testing and hydrothermal dipping treatment do not meet the requirements of the V-0 grade of flame retardancy at a film thickness of 1/32 inch. Therefore, in order to maintain a UL 764C grade of F1, the preferred melt flow rate range for polypropylene is about 4-18 g/10 minutes. EXAMPLE 7 The following components were added into a Hensel mixer and mixed by stirring for 3 minutes: 7.9 kg crystalline polypropylene homopolymer with a melt flow rate of 8 g/10 minutes as the polypropylene resin component, 1.4 kg tetrabromobisphenol A bis-(dibromopropylether) (PE-68 produced by Great Lakes Corporation), 700 g antimony trioxide (Sb 2 O 3 produced by Cheil Flame Retardant, Ltd., 1.2 μm), and as additives, 10 g calcium stearate, 10 g antioxidant (1010 Produced by CIBA GEIGY), 20 g IRGAFOS 168 (produced by CIBA GEIGY), 30 g UV absorber (Tinuvin 326 produced by CIBA GEIGY), 30 g HALS ultraviolet stabilizer (Chimabsorber 944FD produced by CIBA GEIGY), 200 g light-blocking agent TiO 2 (R-103 produced by Dupont, Inc.), and 15 g silane coupling agent (A-174 produced by Union carbide). The mixture was extruded at 190° C. in the form of pellets using a two-axis stirring extruder with a diameter of 30 mm. The extruded pellets were dried for three hours at 100° C. Flame retardancy test pieces were formed using an injection-molding machine with a maximum cylinder temperature fixed at 200° C. Flame retardancy and physical/mechanical properties of the test pieces were determined. The methods of treatment and evaluation were the same as described in Example 1. Results are shown in Table 2. EXAMPLE 8 AND COMPARATIVE EXAMPLES 8-10 The pellets were prepared in the same way as described in Example 1 except that the amount of silane coupling agent, A-174, was modified as shown in Table 2. The pellets extruded in examples 7 and 8 were dried for three hours at 100° C. Flame retardancy test pieces were formed using an injection-molding machine with a maximum cylinder temperature fixed at 200° C. Flame retardancy and physical/mechanical properties of the test pieces were then determined. Results are shown in Table 2. As seen in Table 2, when appropriate amounts of silane coupling agent are added, the adhesiveness between the flame retardant agent and the polypropylene resin and the dispersibility of retardant agent or retardant coagent in the polypropylene resin are improved. A flame retardancy grade of V-0 is achieved and tensile strength is maintained as well. Furthermore, improved environmental resistance provides a UL 764C grade of F1. The preferred range of silane coupling agent is about 0.3-3% by weight. EXAMPLE 9 The following components were added into a Hensel mixer and mixed by stirring for 3 minutes: 7.9 kg crystalline polypropylene homopolymer with a melt flow rate of 8 g/10 minutes as the polypropylene resin component, 1.4 kg tetrabromobisphenol A bis-(dibromopropylether) (PE-68 produced by Great Lakes Corporation), 700 g antimony trioxide (Sb 2 O 3 produced by Cheil Flame Retardant, Ltd., 1.2 μm), and as additives, 10 g calcium stearate, 10 g antioxidant (1010 Produced by CIBA GEIGY), 20 g IRGAFOS 168 (produced by CIBA GEIGY), 70 g UV absorber (Tinuvin 326 produced by CIBA GEIGY), 70 g HALS ultraviolet stabilizer (Chimabsorber 944FD produced by CIBA GEIGY), 200 g light-blocking agent TiO 2 (R-103 produced by Dupont, Inc.), and 70 g silane coupling agent (A-174 produced by Union carbide). The mixture was extruded at 190° C. in the form of pellets using a two-axis stirring extruder with a diameter of 30 mm. The extruded pellets were dried for three hours at 100° C. Flame retardancy test pieces were formed using an injection-molding machine with a maximum cylinder temperature fixed at 200° C. Flame retardancy and physical/mechanical properties of the test pieces were then determined. The methods of treatment and evaluation were the same as described in Example 1. Results are shown in Table 2. EXAMPLE 10 AND COMPARATIVE EXAMPLES 11-16 The pellets were prepared in the same way as described in Example 1 except that the amounts of UV absorber and HALS ultraviolet stabilizer in the composition were modified as shown in Table 2. The extruded pellets were molded using an injection-molding machine to provide test pieces for flame retardancy testing and tensile impact strength testing. Flame retardancy and physical/mechanical properties were then determined Results are shown in Table 2. As seen in Table 2, using a mixture of UV absorber and HALS ultraviolet stabilizer in the appropriate amounts provides improved flame retardancy and environmental resistance. EXAMPLE 11 The following components were added into a Hensel mixer and mixed by stirring for 3 minutes: 8.1 kg crystalline polypropylene homopolymer with a melt flow rate of 8 g/10 minutes as the polypropylene resin component, 1.3 kg tetrabromobisphenol A bis-(dibromopropylether) (PE-68 produced by Great Lakes Corporation), 650 g antimony trioxide (Sb203 produced by Cheil Flame Retardant, Ltd., 1.2 μm), and as additives, 10 g calcium stearate, 10 g antioxidant (1010 Produced by CIBA GEIGY), 20 g IRGAFOS 168 (produced by CIBA GEIGY), 30 g UV absorbent (Tinuvin 326 produced by CIBA GEIGY), 30 g HALS ultraviolet stabilizer (Chimabsorber 944FD produced by CIBA GEIGY), 200 g light-blocking agent TiO 2 (R-103 produced by Dupont, Inc.), and 70 g silane coupling agent (A-174 produced by Union carbide). The mixture was extruded at 190° C. in the form of pellets using a two-axis stirring extruder with a diameter of 30 mm. The extruded pellets were dried for three hours at 100° C. Flame retardancy test pieces were formed using an injection-molding machine with a maximum cylinder temperature fixed at 200° C. Flame retardancy and physical/mechanical properties of the test pieces were then determined. The methods of treatment and evaluation were the same as described in Example 1. Results are shown in Table 2. EXAMPLE 12 AND COMPARATIVE EXAMPLES 17-18 The pellets were prepared in the same way as described in Example 1 except that the amounts of flame retardant agent PE-68 (tetrabromobisphenol A bis-(dibromopropylether)) and flame retardant coagent Sb 203 (antimony trioxide) in the composition were modified as shown in Table 2. The extruded pellets were molded using an injection-molding machine to provide test pieces for flame retardancy testing and tensile impact strength testing. Flame retardancy and physical/mechanical properties were then measured. Results are shown in Table 2. As seen in Table 2, using a mixture of flame retardant agent and coagent in specific amounts improves flame retardancy and environmental resistance. TABLE 1 1,000 hours after Exposing to UV Before Treatment Mainten- Mainten- Flame Tensile Flame Tensile ance ance Composition Component (100 g) retardancy impact retardancy impact of of A B C D E F G (1/32″) strength (1/32″) strength FR TIS(%) E1 79 14 7 0.30 0.30 2.00 0.70 V0 38.5 V0 35.6  M* 92 E2 79 14 7 0.30 0.30 5.00 0.70 V0 39.0 V0 34.1 M 87 CE1 79 14 7 0.30 0.30 0.10 0.70 V0 38.9 V0 26.3 M 68 CE2 79 14 7 0.30 0.30 7.00 0.70 V0 39.4 V0 27.5 M 70 CE3 79 14 7 0.30 0.30 0.00 0.70 V0 36.0 V2 20.1  D* 56 E3 76 14 10 0.30 0.30 2.00 0.70 V0 38.2 V0 35.4 M 93 E4 71 14 15 0.30 0.30 2.00 0.70 V0 37.1 V0 34.1 M 92 CE4 69 14 17 0.30 0.30 2.00 0.70 V0 39.6 V0 27.5 M 69 CE5 83 14 3 0.30 0.30 2.00 0.70 V2 38.3 V2 36.4  B* 95 E5 (A1)79 14 7 0.30 0.30 2.00 0.70 V0 39.5 V0 36.3 M 92 E6 (A2)79 14 7 0.30 0.30 2.00 0.70 V0 35.4 V0 34.1 M 96 CE6 (A3)79 14 7 0.30 0.30 2.00 0.70 V0 44.5 V0 30.4 M 68 CE7 (A4)79 14 7 0.30 0.30 2.00 0.70 V2 32.1 V2 30.4 M 95 168 hours (7 days) after hydrothermal dipping Mainten- Mainten- Flame Tensile ance ance Composition Component (100 g) retardancy impact of of Final A B C D E F G (1/32″) strength FR TIS(%) Grade E1 79 14 7 0.30 0.30 2.00 0.70 V0 42.6 M 111 F1 E2 79 14 7 0.30 0.30 5.00 0.70 V0 39.4 M 101 F1 CE1 79 14 7 0.30 0.30 0.10 0.70 V2 39.4 D 101  NG* CE2 79 14 7 0.30 0.30 7.00 0.70 V0 36.9 M 94 F1 CE3 79 14 7 0.30 0.30 0.00 0.70 V2 42.0 D 117 NG E3 76 14 10 0.30 0.30 2.00 0.70 V0 41.0 M 107 F1 E4 71 14 15 0.30 0.30 2.00 0.70 V0 38.3 M 103 F1 CE4 69 14 17 0.30 0.30 2.00 0.70 V0 37.6 M 95 F2 CE5 83 14 3 0.30 0.30 2.00 0.70 V2 38.4 B 100 NG E5 (A1)79 14 7 0.30 0.30 2.00 0.70 V0 42.6 M 108 F1 E6 (A2)79 14 7 0.30 0.30 2.00 0.70 V0 42.6 M 120 F1 CE6 (A3)79 14 7 0.30 0.30 2.00 0.70 V0 42.6 M 96 F2 CE7 (A4)79 14 7 0.30 0.30 2.00 0.70 V2 32.6 M 102 NG *unit of tensile impact strength: kg · cm/cm square *NG: No Grade *FR: Flame Retardancy, TIS: Tensile Impact Strength, NG: No Grade *M: Maintained, D: Deteriorated, B: Below the standard TABLE 2 1,000 hours after Exposing to UV Before Treatment Mainten- Mainten- Flame Tensile Flame Tensile ance ance Composition Component (100 g) retardancy impact retardancy impact of of A B C D E F G (1/32″) strength (1/32″) strength FR TIS (%) E7 79 14 7 0.30 0.30 2.00 0.15 V0 35.1 V0 28.7 M 82 E8 79 14 7 0.30 0.30 2.00 3.00 V0 32.6 V0 26.4 M 81 CE8 79 14 7 0.30 0.30 2.00 5.00 V0 34.2 V0 25.9 M 76 CE9 79 14 7 0.30 0.30 2.00 0.00 V0 40.2 V0 22.4 M 56 CE10 79 14 7 0.30 0.30 2.00 0.05 V0 37.1 V0 27.5 M 74 E9 79 14 7 0.70 0.70 2.00 0.70 V0 37.0 V0 32.6 M 88 E10 79 14 7 1.50 1.50 2.00 0.70 V0 38.4 V0 30.8 M 80 CE11 79 14 7 0.05 0.05 2.00 0.70 V0 37.4 V0 21.0 M 56 CE12 79 14 7 2.00 2.00 2.00 0.70 V2 32.4 V2 28.2 B 87 CE13 79 14 7 0.00 0.70 2.00 0.70 V0 35.4 V0 17.3 M 49 CE14 79 14 7 0.00 1.50 2.00 0.70 V0 33.5 V0 18.0 M 54 CE15 79 14 7 0.70 0.00 2.00 0.70 V0 36.2 V0 20.3 M 56 CE16 79 14 7 1.50 0.00 2.00 0.70 V0 35.7 V0 22.3 M 62 E11 81 13 6.5 0.30 0.30 2.00 0.70 V0 38.9 V0 31.2 M 80 E12 76 16 8 0.30 0.30 2.00 0.70 V0 32.5 V0 22.6 M 70 CE17 73 18 9 0.30 0.30 2.00 0.70 V0 31.4 V2 15.9 B 51 CE18 89 7 4 0.30 0.30 2.00 0.70 V2 42.3 V2 37.5 B 89 168 hours(7 days) after hydrothermal dipping Mainten- Mainten- Flame Tensile ance ance Composition Component (100 g) retardancy impact of of Final A B C D E F G (1/32″) strength FR TIS (%) Grade E7 79 14 7 0.30 0.30 2.00 0.15 V0 35.2 M 100 F1 E8 79 14 7 0.30 0.30 2.00 3.00 V0 38.6 M 118 F1 CE8 79 14 7 0.30 0.30 2.00 5.00 V2 33.6 D 98 NG CE9 79 14 7 0.30 0.30 2.00 0.00 V2 38.4 D 96 NG CE10 79 14 7 0.30 0.30 2.00 0.05 V2 35.6 D 96 NG E9 79 14 7 0.70 0.70 2.00 0.70 V0 36.3 M 98 F1 E10 79 14 7 1.50 1.50 2.00 0.70 V0 41.4 M 108 F1 CE11 79 14 7 0.05 0.05 2.00 0.70 V0 38.3 M 102 F2 CE12 79 14 7 2.00 2.00 2.00 0.70 V2 33.6 B 104 F2 CE13 79 14 7 0.00 0.70 2.00 0.70 V0 37.9 M 107 F2 CE14 79 14 7 0.00 1.50 2.00 0.70 V0 35.9 M 107 F2 CE15 79 14 7 0.70 0.00 2.00 0.70 V0 37.2 M 103 F2 CE16 79 14 7 1.50 0.00 2.00 0.70 V0 33.6 M 94 F2 E11 81 13 6.5 0.30 0.30 2.00 0.70 V0 39.6 M 102 F1 E12 76 16 8 0.30 0.30 2.00 0.70 V0 33.1 M 102 F1 CE17 73 18 9 0.30 0.30 2.00 0.70 V0 33.0 M 105 F2 CE18 89 7 4 0.30 0.30 2.00 0.70 V2 39.3 B 93 NG *Unit of Composition Component: 100 g, A: Homopolymer of polypropylene with MFR of 8 g/10 min, A1: Homopolymer of polypropylene with MFR of 4 g/10 min, A2: Homopolymer of polypropylene with MFR of 18 g/10 min, A3: Homopolymer of polypropylene with MFR of 2 g/10 min, A4: Homopolymer of polypropylene with MFR of 20 g/10 min, B: Flame retardant agent, C: antimony trioxide, D: UV absorbent, E: HALS ultraviolet stabilizer, F: Titanium Dioxide, G: silane coupling agent In Tables 1 and 2, an “F1” in the column titled “Final Grade” indicates that a V-0 grade of flame retardancy and more than 70% of the initial tensile impact strength are maintained after UV exposure testing and hydrothermal dipping testing. An “F2” indicates that a V-0 grade of flame retardancy and more than 70% of the initial tensile impact strength are maintained after UV exposure testing or hydrothermal dipping testing. A “NG” (No Grade) indicates that the grade is neither F1 nor F2. An “M” (Maintained) in the column titled “Maintenance of FR” indicates that flame retardancy is maintained after treatment, a “B” (Below) indicates a V-2 grade of flame retardancy both before and after treatment, and a “D” (Deteriorated) indicates that an initial V-0 grade of flame retardancy is reduced to V-2. As shown in Tables 1 and 2, the polypropylene resin composition of the present invention, which includes about 40-90% by weight polypropylene resin with a melt flow rate of about 4-18 g/10 minutes, about 9-16% by weight halogen-containing flame retardant additive with a low melt point, about 4-15% by weight antimony oxide in the form of white granules, about 0.2-3.0% by weight ultraviolet stabilizer, about 0.1-5% by weight silane coupling agent, and about 0.2-5% by weight titanium dioxide, exhibits excellent weathering characteristics and maintains excellent physical/mechanical properties as well as a flame retardancy grade of V-0 grade after hydrothermal dipping testing. As described above, the polypropylene resin composition, according to the present invention, exhibits an excellent initial flame retardancy and maintains a high flame retardancy as well as excellent physical/mechanical properties after long-term outdoor exposure and long hydrothermal treatments at a film thickness of 1/32 inch providing a grade of F1 in the UL 746C environmental resistance test. The resin of the present invention can be used in products such as light bulb sockets for Christmas tree lights that may experience long-term outdoor exposure.

The present invention provides a polypropylene resin composition including a polypropylene resin having a melt flow rate of 4-18 g/10 minutes, a flame retardant additive having a low melting point, an antimony oxide, a UV stabilizer, a silane coupling agent, and titanium dioxide as a light-blocking agent. The resin composition of the invention produces products exhibiting excellent flame retarding properties, stability against weather, and maintainability of physical/mechanical properties as shown by maintaining the original flame retarding properties after long periods of outdoor exposure and hydrothermal dipping treatments.

CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of my application Ser. No. 08/227,730, filed Apr. 14, 1994 now U.S. Pat. No. 5,524,795. BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to apparatus for the dispensing of liquids such as foods and condiments. It relates especially to a special connector connecting a dispensing nipple or tip to a condiment supply container, such as a bottle. 2. Background of the Invention Condiments such as mustard, ketchup, mayonnaise, and various other sauces are widely dispensed in restaurants and cafes, and especially in the fast food market. Restaurants have various dispensing systems for these condiments, such as ketchup bottles or mustard bottles. Some of these bottles are rigid, and others are plastic where they can be squeezed. Many of the fast food restaurants have the condiments in small plastic packages. When the customer needs ketchup, for example, he tears off a corner of one of these packages, and squeezes the product (such as mustard or ketchup) onto the sandwich. The use of such packages leaves a lot to be desired, e.g. they are very messy and also they waste a lot of the condiment being dispensed. There have been various schemes developed to try to overcome these objections and develop more efficient condiment dispensers. However, none of these are widely accepted. For example, one such system is shown in U.S. Pat. No. 4,773,569 entitled: "Dispenser for Pasty Matter" issued to Uno Larsson Sep. 17, 1988. That patent shows a container such as a bottle with a neck portion to which is attached a plastic dispenser tip. When the device is hung upside down, the condiment in the container flows into the dispensing tip which has a valve mechanism such that no fluid flows out the end of the tip until pressure is applied by squeezing the plastic tip. The valve system described therein was not entirely satisfactory for some commercial use. SUMMARY OF THE INVENTION This invention includes a novel connector for connecting a condiment dispensing nipple to a condiment supply or storage bottle. The dispensing nipple is a squeezeable plastic mostly cylindrical shape with one end in a converging shape. The lower end of the converging end is open so the condiment escapes when the nipple is squeezed. A double valve is provided inside the nipple. It includes a long rod with a ball valve at the bottom for seating in the converging end of the nipple. The other end of the rod is provided with a larger truncated cone shape to serve as a valve against a seat on the connector. The condiment supply bottle has at one end a threaded neck on which a cap is placed when it is in storage. The other end, or bottom, of the bottle is provided with a recloseable hole with a reuseable closing plug which is attached to the bottle. A connector is used to connect the neck of the bottle to the dispensing nipple. The connector includes outer and inner concentric cylinders which are secured to and made an integral part of an annular ring which has an outside diameter and an inside diameter about the same diameter as the first and second concentric cylinders respectively. The annular ring seals one end of the annular volume or space between the concentric cylinders. The inside of the outer cylinder is provided with threads for threadably receiving the top of the dispensing nipple from the bottom side or side of the cylinder away from the annular ring. The inside of the inner cylinder is provided with internal threads to threadably receive the threaded neck of the storage bottle inserted from the side of the annular ring away from the concentric cylinders. The lower end of the internal concentric cylinder is provided with a seat which mates with the truncated cone valve on the end of the long rod within the dispensing nipple. Thus when the condiment bottle is turned such that the neck is up in regard to the direction of the pull of gravity, the valve seat cooperates with the internal valve of the dispensing nipple to close the internal cylinder. In operation, the connector is positioned between the condiment storage bottle and the dispensing nipple. Then the condiment storage bottle can be suspended upside down and the reinsertable plug is removed from the hole in the bottom. When this occurs, the condiment flows past the valve seat and truncated cone valve into the dispensing nipple. The bottom valve seats within the converging end of the nipple and prevents flow of condiment out. When it is desired to dispense condiment upon food, the dispensing nipple is squeezed. This forces the truncated valve up and moves the ball valve away from the converging end. This causes the condiment to flow out the open end of the converging end. When one wishes to replace the storage bottle or place it in storage, all one has to do is reinsert the plug in the hole and turn the bottle right side up. Then, one unscrews the dispensing nipple and removes it from the storage bottle. This leakproof seal is permitted by the truncated cone valve in the dispensing nipple sealing against the valve seat attached to the inner concentric cylinder. A modified connector includes an annular raised seal on its bottom surface around the edge of the center passage of the connector. When the storage bottle is screwed into the connector, the annular raised seal contacts a ring molded into its neck. As the storage bottle is tightened into the connector, the annular raised seal cuts into the ring on the storage bottle, thereby creating a seal to prevent leakage of fluid from the storage bottle around the connector and down the sides of the dispensing nipple. A modified dispensing nipple includes a shortened rod connecting a semi-spherical ball valve and a truncated cone shaped member. The truncated cone shaped member acts as a valve only when the dispensing nipple is in the inverted position such as to replace an empty storage bottle. The truncated cone shaped member of the modified nipple does not act as a valve during operation when the dispensing nipple is squeezed. In this way, the flow of fluid from the storage bottle into the dispensing nipple is continuous during operation. In the modified dispensing nipple, additional weight is provided for the valve sealing the converging end of the dispensing nipple in order to provide a proper seal. A weighted portion is provided on the top surface of the truncated cone member and an additional weighted portion is provided on the rod adjacent the semi-spherical ball valve. In addition to the added weight, the internal surface of the converging end of the dispensing nipple is provided with a plurality of annular ridges which contact the semi-spherical valve member in order to provide sealing surface to prevent fluid from leaking. While I have referred to condiments, other liquids such as soap, can be dispensed with this system. It is an object of this invention to provide a novel and improved system for dispersing condiments or other liquid like material. It is a specific object of this invention to provide a new and improved connector between a dispensing nipple and a condiment storage bottle or container. Various other objects and a better understanding of the invention can be had from the following description taken in conjunction with the drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an upside down condiment container, a dispensing nipple, and a connector connecting the two. FIG. 2 is an enlarged view of the connector and dispensing nipple shown in FIG. 1. FIG. 3 shows the plastic dispensing nipple. FIG. 4 shows the valve used with the dispensing nipple of FIG. 3 and includes a ball valve, a truncated cone valve, and a rod connecting the two. FIG. 5 is a end view of the valves of FIG. 4. FIG. 6 is similar to the view of FIG. 2 except that pressure has been exerted on the wall of the dispensing nipple. FIG. 7 shows the dispensing unit of FIG. 2 inverted. FIG. 8 is an enlarged view in section form showing the connector between the condiment container and the dispensing nipple. FIG. 9 is a top view of FIG. 8. FIG. 10 illustrates a brush useful for cleaning the internal threads of the connector. FIG. 11 shows an upside down condiment container, a modified dispensing nipple, and a modified connector connecting the two. FIG. 12 is an enlarged view of the modified connector and modified dispensing nipple shown in FIG. 11. FIG. 13 shows a modified dispensing nipple. FIG. 14 shows the valve used with the dispensing nipple of FIG. 13 and includes a semi-spherical ball valve, a truncated cone member including a weighted portion thereon, and a rod connecting the semi-spherical ball valve and truncated cone member. FIG. 15 is similar to the view of FIG. 12 except that pressure has been exerted on the wall of the dispensing nipple. FIG. 16 is an enlarged view in section form showing the connector between the condiment container and the dispensing nipple. FIG. 17 is a bottom view of FIG. 16. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Attention is first directed to FIG. 1 which shows a condiment container 10 and a dispensing nipple 12 which is connected to the container by connector 26. The container 10 is preferably one described in co-pending U.S. patent application, Ser. No. 08/146,405, filed Nov. 2, 1993, by Gary Lee. As shown in FIG. 3, flexible and/or squeezable dispensing nipple 12 has external threads 11 at the upper end. As shown in FIG. 1, the neck of container 10 is provided with threads 13. Also shown in FIG. 3 are guide lines 54, 56, 58, and 60. This makes for quick adjustments for different condiments by cutting back the dispenser tip on these guide lines or ridges. The more you shave or cut off, the larger the hole becomes, and the larger the chunky or lumpy condiments that can be accommodated. Attention is next directed to FIG. 8 which shows a vertical cross-section of connector 26. This connector has two concentric cylinders 32 and 36 with an annular space 42 therebetween. An annular plate 30 closes the space 42 at the upper end thereof when in the position shown in FIG. 8. Outer concentric cylinder 32 is provided with internal threads 34, and inner concentric cylinder 36 contains internal threads 38. As shown in FIG. 1, the internal threads 38 of inner cylinder 36 receive the threads 13 of container 10. Likewise, the internal threads 34 of outer concentric cylinder 32 threadably receive the external threads 11 at the large end of the dispensing nipple 12. The lower end of inner cylinder 36 has a valve seat 40. Attention is next directed to FIGS. 2 and 4. FIG. 4 shows the double headed valve 16. It is provided with a ball valve 20 which, as shown in FIG. 2, seats with the internal wall 25 to prevent the flow of fluids from within dispensing nipple 12 when the device is not operated to dispense such fluid. The upper end of the valve 16 is provided with a valve 18 which essentially takes the shape of a truncated cone having a planar top 19. Stem 22 connects ball valve 20 and valve 18. Below the truncated valve 18 is enlarged section 24 of stem 22 which adds weight to the valve so that it will improve its function. The valve 18 seats against seat 40 which is supported by the inner concentric cylinder 36. As shown in FIG. 7, when the unit is turned upside down, the valve 18 seats on seat 40 of the inner concentric cylinder and prevents fluids from escaping from within the dispenser nipple. Seat 40 of the connector as shown in FIG. 8 is made with angle of about 40° with a plane perpendicular to the axis of the connector. This seat 40 is designed in conjunction with valve 18 so that valve 18 will form a good seal with seat 40. Attention will now be directed toward using the device of this invention. The condiment bottle 10 has a planar side or bottom upon which it may sit and a neck at the other end. When the bottle is sitting on its bottom, it is said to be in the upright position. When in its upright position, the cap of the bottle 10 is removed and the dispensing unit shown in FIG. 2 connected onto the upright bottle. The container 10 preferably has threads 13 which are threadably received by threads 38 of inner cylinder 36 of the connector shown in FIG. 8. After the dispensing unit of FIG. 2 is connected to container 10, the whole assembly is inverted and is hung as by hole 28. When in the position shown in FIG. 1, ball valve 20 seats against the inner wall 25 of the converging end of the nipple 12. This prevents any flow of condiment out of the nipple. The condiments contained in container 10 will normally flow through the neck of the container and through the space 19 between the valve 18 and the seat 40. This space should be big enough to permit flow of the particular condiment or other fluids which may be in container 10. The nipple 12 is thus filled by gravity. During this time the ball valve 20 is seated against the wall 25 of the converging portion of the nipple 12. When the container is hung in the position shown in FIG. 1, there is a removeable plug 29 in the bottom of the planar side of the container 10 near hole 28 which is removed. This permits air flow out and permits the fluid to flow downwardly easily. Sometimes one may be in a hurry to fill the nipple 12. In that case, before screwing the container 10 into a connector 26, one can merely take off the cap of container 10 and pour the fluid, such as ketchup, mustard, etc. through the center passage 27 of connector 26 when the connector is in the position shown in FIG. 2. The fluid will then flow through the space 19 between valve 18 and seat 40. This arrangement is such that there is ample space between space 19 to permit the flow of the fluid. Then, when the nipple 12 is filled, the container 10 is set on its planar surface with the neck upwardly, and the device of FIG. 2 is then turned upside down or inverted from that position to the position shown in FIG. 7. Here it shows that the valve 18 rests on seat 40, and no fluid can escape the filled nipple 12. The apparatus of FIG. 7 is then placed on the threads 13 of the container 10 while the container 10 is in its upright position. Once the apparatus shown in FIG. 7 is screwed on, the container and the apparatus can be inverted to the position shown in FIG. 1. The apparatus of this invention is now ready to be hung by hole 28. One then places one's hot dog or whatever one may wish to have the condiment applied to beneath the opening 23 of the converging end 21. Then the walls of the container 12 are squeezed as indicated in FIG. 6 by arrows 46. This causes the ketchup or whatever may be in there to force the valve 18 upwardly as shown by arrows 48. This raises the ball 20 off of the converging walls 25, and then the fluid or ketchup flows in the path indicated by arrows 50 where is exits the opening 23. The size of nipples 12 is such that one squeeze will normally give all of the condiment that the customer desires. If more is desired, all the customer needs to do is relax his grip, and the condiment will flow downwardly as described above with regard to FIG. 2, and then a second squeeze will permit the second serving of the condiment. When pressure is released, the valve 20 drops to seal against wall 25 of the converging end. If one were to store the condiments while still in the system as shown in FIG. 1, as at the end of the day, one can either hang the entire dispensing system in a refrigerator or other place in the position shown in FIG. 1. Or, if desired, one can remove and invert the dispensing system of FIG. 1 and remove the device shown in FIG. 7 which when in that position, valve 18 is seated on seat 40 and fluid cannot leak out. The bottle cap can be put back on the container, and the container stored. It is quite easy to clean the device of this invention. As shown in FIG. 2, all one has to do after container 10 has been removed is remove connector 26 from the nipple section 12 and remove connected valve 18 and ball valve 20. After removing the connector 26 from the nipple, the nipple can be washed with a brush and suitable cleansing fluid. The connector 26 shown in FIG. 8 can be cleaned in a similar fluid while using the brush of FIG. 10. The brush of FIG. 10 is designed so that brush head 50 can go into the space 42 between the concentric cylinders 32 and 36. The other end of the brush 48 can be used to clean the threads 38. The dispensing apparatus of FIG. 2 has been built. Typically, the connector 26 is made of F.D.A. approved thermo-plastic, the nipple 12 made of F.D.A. approved elastomeric plastic, and the dual valving (18, 20, 22) is made of F.D.A. approved thermo-plastic. One device that was built the following are the dimensions: ______________________________________Connector 26Outside diameter of outer concentric cylinder 32 2.44"Inside diameter of outer concentric cylinder 32 2.06"Outside diameter of inner concentric cyclinder 36 1.6875"Inside diameter of inner concentric cyclinder 36 1.27"Height "H" of connector 26 .78"Valve 16 of FIG. 4Length "L" of valve of FIG. 4 4.825"Radius of valve 20 .234"Diameter of rod 22 .160""M" of valve 18 .532"Diameter of enlarged section 24 .4375"Length "T" of enlarged section 24 .625"Nipple 12 of FIG. 3Diameter of section 62 1.875"Diameter of section 64 1.75"Length "K" of section 62 .59357"Length "P" of section 12 2.46875"Length "Q" of section 66 .875"Diameter at 68 .625"Diameter at 56 .4375"Diameter at 60 .25"Average thickness at wall of nipple 12 .09375"______________________________________ A modified dispensing nipple and modified connector help prevent fluid from leaking from the system. In addition, it has been found that a dispensing nipple that provides continuous flow of fluid with a single squeeze is desireable. Referring to FIG. 11, storage bottle 10 includes a ring 70 molded into its neck. This ring 70 interacts with an annular raised seal 75 of modified connector 74. Annular raised seal 75 of modified connector 74 can be seen in greater detail in FIGS. 16 and 17. FIG. 16 is a vertical cross-section of modified connector 74 and FIG. 17 depicts a bottom view of modified connector 74. Annular raised seal 75 of FIG. 16 is molded into modified connector 74 and tapers to a point extending away from modified connector 74. As can be seen in FIG. 17, annular raised seal 75 encircles the edge of central passage 77 of modified connector 74. Referring again to FIG. 11, in operation, the neck of storage bottle 10 is screwed into modified connector 74, the annular raised seal 75 of modified connector 74 contacts ring 70 of storage bottle 10. As storage bottle 10 is tightened into modified connector 74, the point of annular raised seal 75 cuts into ring 70. When annular raised seal 75 cuts into ring 70, a seal is formed in addition to the threaded connection between storage bottle 10 and modified connector 74. This additional seal helps prevent fluid from leaking around modified connector 74 and modified nipple 72 when the storage bottle, modified connector, modified nipple system is inverted for usage as in FIG. 11 or turned upright for storage or replacement of storage bottle 10. Referring to FIG. 12, the interior circumference of tip 76 includes a plurality of annular ridges 88 and 90. Annular ridges 88 and 90 act in combination with semi-spherical valve 84 in order to provide multiple sealing surfaces to prevent fluid from leaking from tip 76 when modified dispensing nipple 72 is in its resting position. Semi-spherical valve 84 has a very smooth and uniform surface in order to provide a precise seal against annular ridges 88 and 90. Modified dispensing nipple 72 includes a rod 78 which is shorter than rod 22 of FIG. 2. Rod 78 connects a truncated cone shaped member 80 and a semi-spherical ball valve 84. Truncated cone shaped member 80 acts as a valve only when modified dispensing nipple 72 is in the inverted position such as for storage or for replacement of an empty storage bottle 10. Truncated cone shaped member 80 does not act as a valve during operation when modified dispensing nipple 72 is squeezed. In this way, the flow of fluid from the storage bottle into modified dispensing nipple 72 is continuous during operation. Referring to FIG. 15, when the walls of the nipple 72 are squeezed, the fluid in modified dispensing nipple 72 forces the truncated cone shaped member 80 upwardly but not in contact with connector 74. This raises semi-spherical ball valve 84 off of annular ridges 88 and 90 to allow fluid to exit tip 76 but does not prevent fluid from entering dispensing nipple 72. While modified dispensing nipple 72 is squeezed, fluid continues to flow through connector 74, around truncated cone shaped member 80, through dispensing nipple 72 and exits from tip 76. The forces of gravity upon the fluid maintain a constant flow of fluid from storage bottle 10, through modified connector 74 and modified dispensing nipple 72 during time nipple 72 is squeezed. In this way, the user is able to obtain the desired amount of fluid from a single squeeze of nipple 72. Once the squeezing force is released from modified dispensing nipple 72 it returns to its resting position. The forces of gravity continue to act upon the fluid which forces truncated cone shaped member 80 downward since the forces of the fluid within nipple 72 cease to act upon the underside of truncated cone shaped member 80. When truncated cone shaped member 80 is forced down, rod 78 forces semi-spherical valve 84 into contact with annular ridges 88 and 90 to seal tip 76 thereby preventing fluid from exiting. The forces of gravity upon truncated cone shaped member 80 assist in maintaining a good seal of semi-spherical valve 84 with annular ridges 88 and 90. In addition to the forces of gravity acting upon the fluid forcing truncated cone shaped member 80 downward, weight has been added to rod 78 so that semi-spherical valve 84 seats properly on annular ridges 88 and 90. Referring to FIG. 14, a weighted portion 82 is provided to the top surface of truncated cone member 80. A second weighted portion 86 is provided on rod 78 adjacent to semi-spherical ball valve 84. Length "B", FIG. 13, of the large part 87 of modified dispensing nipple 72 is longer than length "K" of large part 62 of nipple 12. This is to accommodate the shorter length rod 78 of the modified dispensing nipple 72, FIG. 12. A modified dispensing nipple and a modified connector were built having the following dimensions: ______________________________________Modified Valve 79 of FIG. 14Length "Z" of valve 79 of FIG. 14 4.875"Radius of semi-spherical valve 84 .234""X" of truncated cone member 80 .750"Length "Y" of enlarged section 81 .438"Modified Nipple 72 of FIG. 13Diameter of section 88 1.875"Diameter of section 89 1.75"Length "B" .750"Length "C" 2.46875"Length "D" .875"______________________________________ While the invention has been described with a certain degree of particularity, it is manifest that many changes may be made in the details of construction without departing from the spirit and scope of this disclosure. It is understood that the invention is not limited to the embodiment set forth herein for purposes of exemplification, but is to be limited only by the scope of the attached claim or claims, including the full range of equivalency to which each element thereof is entitled.

A dispenser comprising a condiment supply container, a squeezeable dispensing nipple, and a connector connecting the container and nipple.

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of U.S. patent application Ser. No. 13/043,589, filed Mar. 9, 2011 and hereby incorporated by reference in its entirety, and claims the benefit thereof. FIELD OF THE INVENTION The present invention relates to stored value media. More specifically, it relates to a headphones holder to which indicia of stored value are attached. BACKGROUND OF THE INVENTION A stored value card is a card that represents some kind of value, typically financial value. For example, a stored value card might be redeemable at a particular store for a certain monetary value in merchandise or services. A stored value card might simply represent an amount of cash, which might be used, for example, as a substitute for a credit or debit card in making any kind of purchase, or to pay off debt. A stored value card might be restricted to a particular set of products or services; for example, it might represent ten deluxe car washes at some gas station. A gift card is a particular kind of stored value card, one purchased by a donor as a gift for, e.g., a friend, a relative, or an employee. A stored value card must typically be activated before it can be used to spend a portion of its stored value. This requirement protects the card retailer by reducing both the likelihood and the consequences of theft while the cards are displayed, and accessible to the public, in a store. The card is activated by an initial scanning at the point of sale at the time when it is purchased, and, at the same time, an initial amount is associated with the card. The initially added funds give the stored value card an initial value balance. The stored value represented by the card is reduced when the card is used to make a purchase. Additional value for the card can typically be purchased from the card issuer or a card seller. In the case of a gift card, the donee or the donor might be able to buy additional stored value. The balance of value remaining on the stored value card may be stored as an account in an electronic recordkeeping system, or database. In this case, the card must contain a device that provides identifying indicia for the account, such as a bar or UPC code, a magnetic stripe, a radio frequency identification (RFID) tag, a smart chip, or other identifying device. In general, account indicia, such as a magnetic stripe or a barcode, and may also include a human readable number and a Product Identification Number (PIN). A stored value card may include a plurality of account indicia, such as a barcode, a human readable number corresponding to the barcode, and a magnetic stripe. In the case of a card with a smart chip, or other device where the card itself contains logic in the form of hardware (including possibly a processor) and/or software instructions, the stored value balance may be maintained within the card itself. When a stored value card is redeemed, for example to make a purchase, then the account balance is reduced by the purchase amount. At a retail establishment, the account balance is usually automatically adjusted at the point of sale by the action of scanning the card, or manually by a salesperson making a data entry. A stereo headset is a pair of speakers, or headphones, that, when in operation, are worn close to a user's ears. A monaural headset may have a single headphone worn on one ear. The headphones include means for communicating from a source, such as a personal audio device, to feed audio through the speakers. Examples of personal audio devices include handheld electronics devices such as portable music players and cell phones; computers; portable video/movie players; recorders; dictation machines, and in-home stereo and television systems. Although this document deals primarily with wired communication, headphones may also be wireless. In a wired headset, wires typically connect the speakers to a connector or jack. The jacks can have a variety of configurations, with different standards for different purposes. A jack having a 3.5 mm diameter is a standard used for portable electronic devices, such as cell phones and portable music players, and laptop computers. A headset also includes means for holding the speakers close to the user's ears. In some headsets, a metal or plastic band straddles the user's head, with the length and/or tension in the band keeping earmuff-style headphones in place. Earbuds, or earphones, are small headphones that are placed inside the user's ear canal. An earbud may be held in place simply by pressure from the ear chamber itself, or may be attached to a holder or brace that goes partially around the ear for this purpose. An earbud headset is lightweight, compact, and relatively inexpensive. Portable music players and cell phones are often packaged for sale together with a compatible earbud headset. Typically, earbud headset wiring will be shaped like the letter ‘Y’. The jack will terminate a single wire of the headset, corresponding to the lower portion of the Y. To provide specificity, we will refer to this single wire is the “jack wire” of the headset. At some junction point, the single wire will fork into a two wires, with a respective earbud terminating each of the wires in the pair. We will refer to this pair of wires as the “earbud wires” of an earbud headset. SUMMARY OF THE INVENTION The wires of some headsets, particularly earbud headphone sets, are flexible, long, and narrow in diameter, so they may be relatively easy to tangle and knot. A headset holder is a device around which the wires of a headset can be wrapped to keep the parts of the headset organized and accessible, and the wires free from tangles, knots, and snags, while the headset is not in use. Exemplary embodiments of the invention include a headset holder that includes two grips and a spool. A spool is a structure about which a wire can be wound. In some such embodiments, earbuds of an earbud headset may be held by one grip, the jack may be held by the other grip, and the bulk of the wire may be wrapped around the spool. In some embodiments, a headset holder may be constructed from an essentially flat sheet of material. The material might be any material, or combination of materials, that is relatively stiff, for example, plastic, cardboard, or metal. In some cases, such a headset holder might be described as having a left side, a right side, a top, and a bottom, the geometry of the holder forming a two dimensional (2D) shape. An extremity, extension, or projection at the top or bottom of the shape (given some orientation that is intuitive given the visual or functional attributes of the shape) might serve as a spool. A projection extending from a side of the shape might serve as a grip. The shape might have extremities on each side, each serving as a grip. A grip may have the shape generally of the letter ‘U’ or the letter ‘L’. The invention encompasses many forms of grips, including all types of structures that can hold a wire, a jack, or a headphone. In some embodiments, the shape may be the shape of a human, an animal, a monster, or a plant. In such embodiments, an extremity terminating in a grip may resemble a feature associated with the shape, such as a hand, claw, paw, or pair of tree limbs. The spool may resemble the head or legs of a monster, creature, or person, the trunk of a tree, the stalk of a plant, or extremity of any type of solid object whether natural or human-devised. The surface of a 2D headset holder may display an image. The image may show a monster, a human, an animal, or a plant. The image may be incorporated onto or into the surface in any way, such as printing, painting. etching, inscribing, imaging (e.g., by drop on demand technology), inkjet, heat lamination, or by combining parts of different shapes and/or colors. The displayed image and the shape of the holder may correspond, so that, for example, the image displays a head on an extremity that resembles a head at the top of the holder, or legs on one or more extremities at the bottom of the holder; or images of arms extending from the left and right sides of the holder, with grips perhaps having images that appear like hands. The combination of a headset holder with a gift card might suggest to a recipient that the gift card be used to purchase a particular type of gift. For example, the donor might want to suggest the purchase of a personal music player, that could be used with the headset. Account indicia may be coupled to, or integrated into, a headset holder in a variety of ways. If the headset holder has a 2D shape, then it might be attached directly to a stored value card. The stored value card may be coplanar with the holder shape. If the holder and stored value card are constructed from a single sheet of material, then a scoreline—an indentation or perforation in the material—may define a boundary between the holder and the card. Bending the card along the boundary relative to the holder may separate the card from the holder. A broad range of materials are available, including plastic, polyvinyl chloride (PVC), polyethylene terephthalate (PET), TESLIN®, styrene, polylactide (biodegradable corn plastic), or paperboard, or cardboard. Account indicia may also be integrated into the holder itself by, for example, printing, painting, or incorporation of a plaque or other object into or onto the holder, thereby combining the functionality of the headset holder with all the advantages of a stored value card. In general, a headset holder with stored value account indicia can have all the capabilities and features of the holder itself. Identifying indicia for the account may be permanently coupled directly to the holder, for example on an external surface. When we say that an account indicium is “permanently coupled” to a headset holder, we mean that the holder is designed to make it difficult for a user to remove the account indicium. For example, the indicium might be printed or painted directly onto the holder. The account indicia might be printed on a plastic or metal plaque. Such plaque or other object containing a surface into which the indicia is printed, embedded, or integrated, might be permanently coupled by glue, by welding, by screws or bolts, or by stitching with thread or other fiber, depending on the type of holder. Some embodiments may include an image that displays a trademark, logo or contact information on a headset holder, which is combined with account indicia, which could be a useful advertising tool. Embodiments of the invention include a method, comprising the steps of: during a transaction, sensing electronically an account indicium coupled to a headset holder; using a processing system, associating the account indicium with information, stored in tangible electronic storage, regarding an account; and reading a stored value balance of the account, or, in an amount corresponding to the transaction, initializing, raising, or lowering the stored value balance. Embodiments of the invention include an account maintenance system, comprising: a set of software instructions stored in tangible storage; a stored value balance, stored in tangible storage, the stored value balance identified by an account identifier; and processing hardware that (i) receives a transaction request and the account identifier through a communication system, the account identifier having been obtained by accessing account indicia permanently coupled to a headset holder, (ii) retrieves and executes the software instructions, and (iii) updates the stored value balance identified by the account identifier consistently with the transaction request. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view of an exemplary headset holder with stored value account indicia. FIG. 2 is a rear view of an exemplary headset holder with stored value account indicia. FIG. 3 is a front view of an exemplary headset holder with stored value account indicia, depicted holding an earbud headset. FIG. 4 is a rear view of an exemplary headset holder with stored value account indicia, depicted holding an earbud headset. FIG. 5 a is an exemplary slotted grip for holding wires in a headset holder with stored value account indicia. FIG. 5 b is an exemplary slit grip for holding wires in a headset holder with stored value account indicia. FIG. 5 c is an exemplary grip, which uses hook and loop technology, for holding wires in a headset holder with stored value account indicia. FIG. 5 d shows an elastic band that might be used in a headset grip. FIG. 5 e shows a cord that might be used in a headset grip. DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS Illustrative embodiments of the invention are described by the drawings and the accompanying text below. A person having skill in the art will recognize that many other embodiments and variations are possible within the scope of the invention that couples indicia of stored value with a holder for a headset. FIGS. 1 and 2 are front and rear views of a headset holder with stored value account indicia 100 . In this embodiment, a headset holder 110 and a stored value card 150 are fabricated from a single sheet of plastic. The headset holder 110 resembles a creature or monster-person. Between the headset holder 110 and the stored value card 150 is an indentation 190 or a series of perforations in the plastic sheet, making the stored value card 150 separable from the headset holder 110 . The illustrated headset holder 110 includes a spool 111 and two grips 112 . Other than being flat, the spool 111 in this embodiment appears similar to a spool used to hold thread for sewing. The top of this spool is capped with a decorative flange 114 . The body 116 , or central portion 116 of the creature headset holder 110 serves as a flange workalike for holding wire 301 of a headset 300 , in this case an earbud headset 333 . The grips 112 in this embodiment are extremities 115 or extensions 115 from the body 116 of the headset holder 110 , here limbs or members of a creature. The grips 112 are wire-grips, in other words, grips 112 that are configured for holding wires 301 of the headset 300 . In this case, the grips 112 are simple U-shaped indentations in the extremities 115 . In this embodiment, an image 113 is printed on the headset holder 110 , namely, a caricature of a monster. The image 113 represents arms of the monster on the extremities 115 that include the grips 112 . The head of the monster in the image 113 coincides with the spool 111 , which is another extremity 115 of the body 116 . The legs 117 are extremities 115 of the monster that form its base and connect the headset holder 110 to the stored value card 150 along indentation 190 . In some circumstances, a person or organization might want to give a headset holder with stored value account indicia 100 as a form of advertising, for example: as a reward to loyal customers; as a way of increasing awareness of a company's name and contact information to clients or client prospects; or as an incentive to visit a store, or to purchase a particular item. In such cases, the headset holder with stored value account indicia 100 might display a company logo or icon, such as the advertising material 153 shown in FIGS. 1 and 3 . Other characteristics of the headset holder 110 or stored value card 150 might also serve to promote a brand. For example, the headset holder 110 in FIG. 3 might be colored yellow, in accord with trademarks of BBY Solutions, Inc. Thus, the color might call a trademarked symbol to mind for some observers of the headset holder 110 or stored value card 150 . The headset holder with stored value account indicia 100 in FIG. 1 has attributes 151 that may suggest a company brand, and indeed may be a trademark. In this case, the corners of the stored value card 150 have scallop-shaped cutouts. Attributes 151 such as color, shape, and printed matter may serve this purpose, whether incorporated with the headset holder 110 , the stored value card 150 , or both. The illustrated stored value card 150 also has advertising material 153 in the form of a logo 152 . FIG. 2 is the rear view of the headset holder with stored value account indicia 100 shown in FIG. 1 . The stored value card 150 contains an account indicium 200 of the stored value account. In this case, the account indicium 200 is a magnetic stripe 201 , but other types of account indicia 200 , such as a barcode 400 or an RFID tag, might be used. A given headset holder with stored value account indicia 100 may have just one account indicium 200 , or might have two or more of them. FIG. 3 is the front view of a headset holder with stored value account indicia 100 , whose headset holder 110 is similar to the one shown in FIG. 1 . In this case, the headset holder 110 is shown holding a headset 300 , in particular, an earbud headset 333 . The earbud headset 333 includes a jack 310 and a pair of earbuds 320 . The jack 310 is connected to the earbuds 320 by wire 301 that has a Y-shape. The Y-shape wire 301 includes a jack wire 311 and two earbud wires 321 , joined at a junction 410 . The jack 310 and jack wire 311 are secured by one grip 112 . The pairs of earbuds 320 and earbud wires 321 are secured by the other grip 112 . Around the spool 111 , wire 301 (a combination of jack wire 311 and earbud wire 321 ) is wrapped. Note that, in this embodiment, the flange 114 at the top of this headset holder 110 plays no role in holding the wire 301 , being merely decorative. FIG. 3 shows that advertising material 153 , in this case a logo 152 , may be included in the headset holder 110 . FIG. 4 is the rear view of a headset holder with stored value account indicia 100 , similar to that shown in FIGS. 1 and 3 . However, in this case, the top flange 114 on the spool 111 has been removed to emphasize that it is nonfunctional. Note that the spool 111 might be tapered, with the bottom of the spool 111 being narrower than the top, to assist in keeping the wrapped wire 301 in place. In this embodiment, an account indicium 200 is incorporated directly into the headset holder 110 itself, in this case a barcode 400 . A separable stored value card 150 is unnecessary in this embodiment, where the account indicia 200 is permanently coupled to the headset holder 110 itself. An account indicium 200 associates the headset holder with stored value account indicia 100 with a particular account identifier 650 , which identifies a unique account. Account information may be maintained in an account maintenance system 600 , as later described in connection with FIGS. 6 and 7 . Grips 112 of a headset holder 110 may have a many forms. FIG. 5 a - 5 c show a few exemplary structures, but many others are possible. FIG. 5 a illustrates a 2D grip 112 , namely a slot grip 500 , that includes a slot 501 . Wire 301 can be pulled through the slot 501 , and secured within a chamber 502 . The slot grip 500 requires some flexibility in surrounding plastic to get the wire 301 into and out from the chamber 502 . FIG. 5 b is another 2D grip 112 , namely, a slit grip 510 , containing a slit. The account indicia 200 allow the headset holder with stored value account indicia 100 to be scanned, the scanning possibly accomplishing several purposes. An initial scan by a POS system of the headset holder with stored value account indicia 100 may establish an initial balance. A particular headset holder with stored value account indicia 100 might have a fixed initial balance, or the user (e.g., a donor or donee) might be free to specify and purchase an initial balance, which might be entered by a salesperson at POS into the account maintenance system 600 . The initial scan might also activate the account, so that the account maintenance system 600 will allow future purchases of goods or services or other expenditures to be made against the stored value. The initial scan might also update inventory data pertaining to this or a similar headset holder with stored value account indicia 100 , and update transactional data pertaining to the purchase and activation. Subsequent scans can be used to reduce the stored value to make purchases or expenditures. In some embodiments, additional stored value can be purchased, which typically would also involve scanning the headset holder with stored value account indicia 100 . FIG. 5 c illustrates a headset holder 110 that utilizes hook and loop 520 technology to hold wire 301 . A similar approach could be used to secure a pair of wires 301 , or to hold a jack 310 or earbuds 320 directly. An outer segment 522 might contain hooks on its interior surface, and an inner segment 521 might contain loops on its outer surface, or conversely. Many other types of grips 112 , such as a grip 112 that incorporates an elastic band 530 or cord 531 , that secures wires, jack or headphones, are also within the scope of the invention. FIG. 6 is a schematic showing an exemplary account maintenance system 600 for maintaining a stored value balance associated with a headset holder with stored value account indicia 100 . The account maintenance system 600 includes processing hardware 601 that executes logic represented in hardware and/or software. The processing hardware 601 might include a hardware processor 602 , such as the kind of processor 602 that might be included in a computer or a smart cell phone. Some or all of the functionality of the account maintenance system 600 might be performed by the headset holder with stored value account indicia 100 itself, through a smart chip or an internal processing system. A smart chip, such as an RFID tag, might draw power from a battery or external source. Preferably, it will contain a logic in the form of hardware/and or software instructions, that would draw power from a scanner or reader device, so that account information and stored value balance might be changed within the headset holder with stored value account indicia 100 itself. The account maintenance system 600 might be a processing system—by a “processing system” we mean one or more devices having processors 602 , such as computers, possibly communicating over one or more networks or any other electronic communications systems, and utilizing one or more storage devices and peripheral devices, possibly under the management of one or more persons or entities, and controlled by various logical units such as hardware and software programs. The logic might be wholly or partially in the form of software instructions 612 , which might be stored in some form of tangible storage 610 , and retrieved by the processing hardware 601 as needed. The tangible storage 610 might be a hard drive, an optical disk, a memory card, or any other volatile or non-volatile hardware device that can retain information in electronic form. A stored value balance 611 associated with the headset holder with stored value account indicia 100 will also be stored in tangible storage 610 , which might be within the same device or a different device from the device(s) containing the software instructions 612 . The stored value balance 611 might be stored in a database, file, or any other information storage representations. If the stored value balance 611 is maintained in a database, an account identifier 650 might be used to associate the correct stored value balance 611 with this particular headset holder with stored value account indicia 100 . In the example shown in FIG. 6 , a POS system 630 includes a scanner 631 . A transaction (e.g., report account balance; purchase an item; increase account balance) involving the headset holder with stored value account indicia 100 can be performed by scanning the account indicium 200 that is permanently coupled to the headset holder with stored value account indicia 100 . In this example, an account identifier 650 is read by the scanner 631 and provided to the POS system 630 . The POS system 630 transmits a transaction request 651 for the appropriate transaction, along with the account identifier 650 to the account maintenance system 600 . The account maintenance system 600 handles the transaction by executing software instructions 612 on the processor 602 , which accesses the stored value balance 611 , and modifies the balance accordingly if necessary. A transaction response 652 is then returned by the account maintenance system 600 to the POS system 630 , showing the current, possibly updated, stored value balance 611 . FIG. 7 is a flowchart illustrating an embodiment of the invention. After the start 700 , some functionality of a type of headset holder with stored value account indicia 100 is advertised 710 . The “type” might be, for example, a particular manufacturer, vendor, brand, model, or SKU of the headset holder with stored value account indicia 100 . The functionality might be any feature of the headset holder with stored value account indicia 100 , such as the combination of a headset holder 110 and stored value capability. As described previously, a headset holder with stored value account indicia 100 integrates stored value functionality into a headset holder 110 . The advertising might be by any method employed by a seller of the type of headset holder with stored value account indicia 100 ; for example, a newspaper advertisement; online publication of products and their capabilities; an in-store display of a headset holder with stored value account indicia 100 for sale; or a demonstration by a salesperson of a headset holder with stored value account indicia 100 to a customer. Note that some embodiments of the methods of the invention do not include this advertising step. An account identifier 650 contained in account indicia 200 , printed on, or otherwise permanently integrated into, the surface of the headset holder with stored value account indicia 100 , is sensed 730 electronically during a transaction. For example, the transaction might be to read the stored value balance associated with the headset holder with stored value account indicia 100 ; initialization or activation of the stored value in the headset holder with stored value account indicia 100 ; purchase of the headset holder with stored value account indicia 100 ; purchase of goods or services, or payment of debt, using the headset holder with stored value account indicia 100 ; other expenditure of value from the headset holder with stored value account indicia 100 ; increase in the stored value of the headset holder with stored value account indicia 100 ; or any other transaction involving scanning the headset holder with stored value account indicia 100 . Sensing might involve any kind of equipment, such as a handheld device or a POS scanner. Sensing might use any technology, such as radio frequencies, laser, charge-coupled device (CCD) technology, Contact Image Sensor (CIS) technology, photomultiplier tube technology, photographic scanning, or 3D scanning technology. Sensing might be performed actively by a person, or passively by an automated sensing device such as an RFID sensor. The person might be anyone, such as an employee of a store that is selling the headset holder with stored value account indicia 100 , applying the stored value to a purchase, or adding stored value to the headset holder with stored value account indicia 100 ; it might be a headset holder with stored value account indicia 100 purchaser, giver, recipient, or owner. The account identifier 650 will usually be a sequence of letters and/or numerals, but it could be any combination of symbols that might uniquely identify an account. The account indicium 200 might be a magnetic strip, a barcode 400 , a smart chip, a RFID tag, or any other type of device from which a sensor might sense or read an account identifier 650 . “Electronically” merely implies that some aspect of the sensing involves electricity. Using a processing system (defined broadly, as described previously), the account identifier is associated 740 with information stored in tangible electronic storage regarding an account. Note that the account may not exist in the storage prior to the transaction. For example, upon activation of a headset holder with stored value account indicia 100 , data regarding an account may be initialized within the storage 610 , but association will be performed nevertheless between the account indicium 200 and the new account. A stored value balance 611 of the account is read from storage 610 , or, in an amount corresponding to the transaction, initialized, raised, or lowered 750 . For example, the stored value balance 611 might be initialized at when a donor purchases a headset holder with stored value account indicia 100 as a gift and the headset holder with stored value account indicia 100 is activated. The stored value balance 611 might be lowered when a recipient of a gift headset holder with stored value account indicia 100 uses the headset holder with stored value account indicia 100 to make a purchase. The stored value balance 611 might be increased upon activation, if the account already exists in storage 610 with a zero balance. This might also be regarded as initialization of the stored value balance 611 . The stored value balance 611 might also be increased, for example, by a recipient of a gift headset holder with stored value account indicia 100 (or by the original giver or anyone else) by a purchase of additional stored value. The process ends 760 . In other embodiments, the stored value balance 611 is retrieved upon sensing. Of course, many variations of the above embodiments are possible within the scope of the invention. For example, the illustrative embodiments herein have focused on a 2D holder for earbud headphones. All other forms of headsets and headset holders, coupled to an indicium of stored value, are within the scope of the invention. The present invention is, therefore, not limited to all the above details, as modifications and variations may be made without departing from the intent or scope of the invention. Consequently, the invention should be limited only by the following claims and equivalent constructions.

The present invention is a headset holder coupled with indicia of stored value. The indicia of stored value may be printed or painted on, or otherwise permanently coupled to, the holder itself, or may be included in a stored value or gift card that is attached to the holder. The headset holder and the stored value card may be constructed from a single sheet of plastic; in such embodiments, separation of the stored value card from the headset holder may be supported by a scoreline in the plastic material. The headset holder may have a spool and two grips. One grip may be configured to secure earphones and the other grip may be configured to secure a jack of the headset. The spool may be configured for winding headset wire. The holder may be configured to hold primarily an earbud headset. The grips may extend or protrude from a central portion, or body of the holder. The spool may also extend from the body. The holder may display an image, such as the image of a creature or plant. The image may depict the grips as hands of a displayed creature. The image may depict the spool as the head of the creature.

CROSS-REFERENCE TO RELATED APPLICATION The present application claims priority from Japanese application JP 2008-187246 filed on Jul. 18, 2008, the content of which is hereby incorporated by reference into this application. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device and a manufacturing method therefor. More particularly, the present invention relates to an image display device with a built-in driver circuit which includes a driver circuit on a substrate, and a method of manufacturing the image display device. 2. Description of the Related Art There has been known a type of liquid crystal display device which uses a thin film transistor (hereinafter may simply be referred to as TFT) with a semiconductor film made of amorphous silicon, especially a bottom gate TFT which includes a gate electrode provided on a substrate side with respect to the semiconductor film (underside of the semiconductor film), as a switching element for driving a pixel (a TFT as this may hereinafter be referred to as pixel TFT). Channel etch TFTs are known as one of the above-mentioned bottom gate TFTs. A channel etch TFT is formed by: forming a layered structure through sequential patterning of a gate, a gate insulator film, a semiconductor film, and a contact layer; forming a metal film in a manner that covers the sequentially layered structure; processing the metal film to form a source and a drain; and etching portions of the contact layer that are not covered with the source and drain electrodes, along with part of the semiconductor film formed below the etched contact layer. In a TFT having this structure, an influence of an electric field from the gate electrode hardly reaches a front side of the semiconductor film (herein, a top side of a semiconductor film is the front side), whereas the influence of an electric field from above often reaches the front side of the semiconductor film, resulting in a problem that leak current occurs on the front side of the semiconductor film. An example of solutions to this inconvenience is disclosed in JP 2002-305306 A, in which the front side of the semiconductor film is made porous and accordingly low in mobility, to thereby reduce leak current due to an external electric field. Other known methods involving forming a low-mobility layer than the ion irradiation method described in JP 2002-305306 A include one disclosed in JP 2003-37270 A which uses oxygen plasma and hydrogen plasma. JP 2007-95190 A discloses a liquid crystal display device having a built-in driver circuit with a TFT using an amorphous Si semiconductor film. In JP 2007-95190 A and in JP 2002-175053 A, a dual gate TFT which has gates above and below the semiconductor film constitutes a part of the driver circuit of the liquid crystal display device. In the above-mentioned image display devices, forming a circuit that drives a gate of a pixel with an amorphous silicon TFT (a TFT for this use is hereinafter referred to as gate driver TFT) makes the gate driver TFT, which writes in a gate line, large in size and increases a circuit width. A TFT using a semiconductor film that is made of polycrystalline silicon, on the other hand, is superior in driving power and reduced in TFT size. However, manufacturing a polycrystalline silicon TFT requires processes that are not employed in a manufacture line for an amorphous silicon TFT, such as crystallization, impurity implantation, and activation. The driving power of a gate driver TFT can be improved by forming a top gate above the semiconductor film of the gate driver TFT with a second gate insulator film interposed therebetween, thus giving the gate driver TFT a dual gate TFT structure in which a channel is formed on the front side of the semiconductor film as well. This is because the mobility on the front side of the semiconductor film is desirably high in order to improve the driving power. On the other hand, low mobility on the front side of the semiconductor film is desirable in a TFT that is used as a pixel switch and needs to suppress leak current. In the conventional liquid crystal display devices, no consideration has been given to differentiate the mobility on the front side of the semiconductor film of a pixel TFT from the mobility on the front side of the semiconductor film of a gate driver TFT by, for example, employing different processes. Consequently, combining different characteristics required of the two TFTs has been difficult. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an image display device capable of suppressing leakage in a pixel TFT while being improved in driving power of a gate driver TFT, and a method of manufacturing the image display device. A liquid crystal display device according to the present invention is capable of suppressing leakage in a pixel TFT and of improving the driving power of a gate driver TFT by forming a low mobility layer on a front side of a semiconductor film of the pixel TFT while forming no low mobility layer on a front side of a semiconductor film of the gate driver TFT, which has a dual gate structure, or selectively removing a low mobility layer from the front side of the semiconductor film of the gate driver TFT. At the time when a low mobility layer is formed on the front side of the semiconductor film of the pixel TFT, the front side of the semiconductor film of the gate driver TFT is protected, whereby a low mobility layer is formed only in the pixel TFT. The mobility on the front side of the semiconductor film of the gate driver TFT is thus made higher than the mobility on the front side of the semiconductor film of the pixel TFT. The mobility on the front side of the semiconductor film of the gate driver TFT can be made higher than the mobility on the front side of the semiconductor film of the pixel TFT also by forming a low mobility layer on the front side of each of the semiconductor films of the pixel TFT and the gate driver TFT, and then etching the low mobility layer on the front side of the semiconductor film of the gate driver TFT alone. Alternatively, the mobility on the front side of the semiconductor film of the gate driver TFT can be made higher than the mobility on the front side of the semiconductor film of the pixel TFT by forming the TFTs in a manner that forms a source and a drain for the pixel TFT, as well as a low mobility layer on the front side of the semiconductor film of the pixel TFT, and then forms a source and a drain for the gate driver TFT, with the pixel TFT being protected. Another way to make the mobility on the front side of the semiconductor film of the gate driver TFT higher than the mobility on the front side of the semiconductor film of the pixel TFT is to form the TFTs in a manner that forms a source and a drain for the gate driver TFT, and then forms a source and a drain, as well as a low mobility layer on the semiconductor film, for the pixel TFT, with the gate driver TFT being protected. For example, the present invention may be structured as follows. (1) An image display device according to the present invention comprises, for example, on a TFT substrate: a plurality of gate lines and a plurality of drain lines which intersect with each other; a pixel TFT provided within a pixel which is enclosed by a pair of adjacent gate lines and a pair of adjacent drain lines; a gate driver TFT which is connected to one of the plurality of gate lines to drive the one of the plurality of gate lines; and a shift register for selecting one of the plurality of gate lines through the gate driver TFT, wherein the pixel TFT and the gate driver TFT each include an amorphous semiconductor film as a channel, wherein the pixel TFT has a bottom gate structure in which a gate of the pixel TFT is formed below the amorphous semiconductor film, wherein the gate driver TFT has a dual gate structure in which a gate of the gate driver TFT is formed below the semiconductor film and another gate of the gate driver TFT is formed above the semiconductor film, and wherein a mobility on a top surface side of the semiconductor film of the gate driver TFT is higher than a mobility on a top surface side of the semiconductor film of the pixel TFT. (2) In the image display device according to Item (1), the pixel TFT and the gate driver TFT each may include a contact layer which is interposed between a source thereof and the semiconductor film, and between a drain thereof and the semiconductor film. (3) In the image display device according to Item (1), a thickness of the amorphous semiconductor film formed in a region that is not covered with the source and drain of the pixel TFT may be larger than a thickness of the amorphous semiconductor film formed in a region that is not covered with the source and drain of the gate driver TFT. (4) In the image display device according to Item (1), the TFT substrate may face a counter substrate across a liquid crystal. (5) According to the present invention, there is provided a method of manufacturing an image display device that comprises, for example, on the same substrate, a bottom gate type pixel TFT, which includes a gate thereof below a semiconductor film, and a dual gate type gate driver TFT, which has a gate thereof below a semiconductor film and another gate thereof above the semiconductor film, the method comprising: forming a semiconductor layer and a contact layer sequentially to form a sequentially layered structure for each of the bottom gate type pixel TFT and the dual gate type gate driver TFT; forming a source and a drain on the sequentially layered structure of the bottom gate type pixel TFT, and then etching an exposed part of the contact layer which is not covered with the source and drain of the bottom gate type pixel TFT until the semiconductor film formed below the contact layer is exposed; forming a source and a drain on the sequentially layered structure of the dual gate type gate driver TFT, and then etching an exposed part of the contact layer which is not covered with the source and drain of the dual gate type gate driver TFT until the semiconductor film formed below the contact layer is exposed; and forming, while covering at least a region for forming the dual gate type gate driver TFT with a mask, a low mobility layer on an exposed semiconductor film surface which is not covered with the source and drain of the bottom gate type pixel TFT. (6) According to the present invention, there is provided a method of manufacturing an image display device that comprises, for example, on the same substrate, a bottom gate type pixel TFT, which includes a gate thereof below a semiconductor film, and a dual gate type gate driver TFT, which has a gate thereof below a semiconductor film and another gate thereof above the semiconductor film, the method comprising: forming a semiconductor layer and a contact layer sequentially to form a sequentially layered structure for each of the bottom gate type pixel TFT and the dual gate type gate driver TFT; forming, in each of the bottom gate type pixel TFT and the dual gate type gate driver TFT, a source and a drain on the sequentially layered structure, and then etching an exposed part of the contact layer which is not covered with the source and the drain until the semiconductor film formed below the contact layer is exposed; forming a low mobility layer on an exposed semiconductor film surface that is not covered with the source and drain of the bottom gate type pixel TFT and on an exposed semiconductor film surface that is not covered with the source and drain of the dual gate type gate driver TFT; and removing, while covering at least a region for forming the bottom gate type pixel TFT with a mask, the low mobility layer that has been formed on the semiconductor film surface of the dual gate type gate driver TFT. (7) The method of manufacturing the image display device according to Item (5) may comprise: forming, while covering a region for forming the dual gate type gate driver TFT with a first mask, a source and a drain on the sequentially layered structure in a region for forming the bottom gate type pixel TFT, and then etching an exposed part of the contact layer which is not covered with the source and drain of the bottom gate type pixel TFT until the semiconductor film formed below the contact layer is exposed, to form a low mobility layer on an exposed semiconductor film surface which is not covered with the source and drain of the bottom gate type pixel TFT; and forming, while covering the region for forming the bottom gate type pixel TFT with a second mask, a source and a drain on the sequentially layered structure in the region for forming the dual gate type gate driver TFT, and then etching an exposed part of the contact layer which is not covered with the source and drain of the dual gate type gate driver TFT until the semiconductor film formed below the contact layer is exposed. (8) The method of manufacturing the image display device according to Item (5) may comprise: forming, while covering a region for forming the bottom gate type pixel TFT with a first mask, a source and a drain on the sequentially layered structure in a region for forming the dual gate type gate driver TFT, and then etching an exposed part of the contact layer which is not covered with the source and drain of the dual gate type gate driver TFT until the semiconductor film formed below the contact layer is exposed; and forming, while covering the region for forming the dual gate type gate driver TFT with a second mask, a source and a drain on the sequentially layered structure in the region for forming the bottom gate type pixel TFT, and then etching an exposed part of the contact layer which is not covered with the source and drain of the bottom gate type pixel TFT until the semiconductor film formed below the contact layer is exposed, to form a low mobility layer on an exposed semiconductor film surface which is not covered with the source and drain of the bottom gate type pixel TFT. The above-mentioned structures are merely given as examples, and the present invention can be modified to suit individual cases without departing from its technical concept. Other structural examples of the present invention than the above-mentioned structures become clear from the entire description herein or the accompanying drawings. According to the thus structured image display device and image display device manufacturing method, leakage in the pixel TFT can be suppressed and the driving power of the gate driver TFT can be improved. Other effects of the present invention are revealed by reading the entire description herein. BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings: FIG. 1 is a cross-sectional view illustrating a pixel TFT and a gate driver TFT of an image display device according to a first embodiment of the present invention; FIG. 2 is a diagram illustrating an equivalent circuit of the image display device according to the first embodiment; FIG. 3 is a plan view illustrating a pixel of the image display device according to the first embodiment; FIG. 4 is a plan view illustrating the gate driver TFT of the image display device according to the first embodiment; FIG. 5 is a diagram illustrating a cross section taken along line C-C′ of FIG. 4 ; FIG. 6 is a diagram illustrating a first step of an image display device manufacturing method according to the first embodiment; FIG. 7 is a diagram illustrating a second step of the image display device manufacturing method according to the first embodiment; FIG. 8 is a diagram illustrating a third step of the image display device manufacturing method according to the first embodiment; FIG. 9 is a diagram illustrating a fourth step of the image display device manufacturing method according to the first embodiment; FIG. 10 is a diagram illustrating a fifth step of the image display device manufacturing method according to the first embodiment; FIG. 11 is a diagram illustrating a sixth step of the image display device manufacturing method according to the first embodiment; FIG. 12 is a cross-sectional view illustrating a pixel TFT and a gate driver TFT of an image display device according to a second embodiment of the present invention; FIG. 13 is a diagram illustrating a step in an image display device manufacturing method according to the second embodiment; FIG. 14 is a diagram illustrating a step in the image display device manufacturing method according to the second embodiment; FIG. 15 is a diagram illustrating a step in an image display device manufacturing method according to a third embodiment of the present invention; FIG. 16 is a diagram illustrating a step in the image display device manufacturing method according to the third embodiment; FIG. 17 is a diagram illustrating an equivalent circuit of an image display device according to a fourth embodiment of the present invention; FIG. 18 is a cross-sectional view illustrating a pixel TFT and a gate driver TFT of an image display device according to a fourth embodiment of the present invention; FIG. 19 is a plan view illustrating a pixel of the image display device according to the fourth embodiment; FIG. 20 is a plan view illustrating the gate driver TFT of the image display device according to the fourth embodiment; and FIG. 21 is a cross-sectional view taken along line F-F′ of FIG. 20 . DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention are described below with reference to the drawings. Throughout the drawings and the embodiments, the same or similar components are denoted by the same reference symbols in order to avoid repetitive description. FIG. 1 is a cross-sectional view illustrating structures of a pixel TFT and gate driver TFT according to this embodiment. The pixel TFT is illustrated on the left-hand side of FIG. 1 , and the gate driver TFT is illustrated on the right-hand side of FIG. 1 . The cross-sectional view of the pixel TFT corresponds to a cross-sectional view taken along the line A-A′ of FIG. 3 which is described later. The cross-sectional view of the gate driver TFT corresponds to a cross-sectional view taken along the line B-B′ of FIG. 4 which is described later. As illustrated in FIG. 1 , the pixel TFT is a bottom gate TFT which has part of a gate line GL as a gate GT. The gate GT is provided on a substrate SUB 1 made of, for example, glass, and a semiconductor film AS made of amorphous silicon is formed above the gate GT with a first gate insulator film GI 1 interposed therebetween. The semiconductor film AS is connected to a drain DT and a source ST through a contact layer CN made of n + Si. The drain DT is connected to a drain line DL. The source ST is connected through a through hole TH 1 a pixel electrode PX, which is a transparent electrode. The source ST is also connected to a storage capacitor that holds a voltage of the pixel electrode PX. The storage capacitor is formed of the above-mentioned source, a capacitor line CL, and the first gate insulator film GI 1 as a dielectric film. A low mobility layer LML is formed on the semiconductor film AS of the pixel TFT to suppress leakage due to fixed charges of a passivation film PAS or other films above the pixel TFT, or due to an electric field from the pixel electrode PX. The gate driver TFT is a dual gate TFT in which a first gate GT 1 and a second gate GT 2 are formed, respectively, below and above the semiconductor film AS made of amorphous silicon. The first gate GT 1 is a metal film on the same layer as the gate GT of the pixel TFT, and faces the semiconductor film AS with the first gate insulator film GI 1 interposed therebetween. The second gate GT 2 is a transparent conductive film on the same layer as the pixel electrode PX. A region of the second gate GT 2 that is located in an opening OP of the passivation film PAS faces the semiconductor film AS with a second gate insulator film GI 2 alone interposed therebetween in order to facilitate induction of carriers. No low mobility layer is formed on a front side of the semiconductor film AS of the gate driver TFT, which gives the gate driver TFT a current driving power approximately twice larger than that of a bottom gate TFT of the same size. This means that the same driving power is obtained with a TFT approximately half in size, and a circuit width thereof can thus be reduced. The mobility on the front side of the semiconductor film AS of the gate driver TFT is thus made larger than the mobility on the front side of the semiconductor film AS of the pixel TFT, thereby obtaining a structure that has both a driving power required of the gate driver TFT and low leakage properties required of the pixel TFT. FIG. 2 illustrates an example of an equivalent circuit of an image display device according to this embodiment. A plurality of intersecting drain lines DL and gate lines GL (Gn) are formed on the substrate SUB 1 , and pixel TFTs which serve as switches are formed near the intersections between the gate lines GL and the drain lines DL. The pixel TFTs are bottom gate TFTs which have the gate GT only below the semiconductor film AS, and have a low mobility layer formed on the front side of the semiconductor film AS. Agate driver circuit V which drives the gate lines GL is formed on the same substrate SUB 1 . A storage capacitor C for holding the voltage of the pixel electrode PX is formed in each pixel PIX, and is connected to the capacitor line CL and the source ST of the pixel TFT. The drain DT of the pixel TFT is connected to one of the drain lines DL. The gate GT of the pixel TFT is connected to one of the gate lines GL. The gate line GL is connected to one of gate driver TFTs included in the gate driver circuit V. The gate driver circuit V selects the gate lines GL sequentially, one stage at a time, to apply a voltage VGH, which corresponds to ON voltage. When a pixel TFT that is connected to the selected gate line GL is turned on, a signal from the drain line DL is written in the storage capacitor C via the pixel TFT. After the signal is written, the pixel TFT is turned off by setting the voltage of the gate line GL to a voltage VGL, which corresponds to OFF voltage, and the voltage written in the storage capacitor C is held. An image is displayed by selecting the gate lines GL sequentially to write in pixels connected to the gate lines GL, causing the storage capacitor C of each pixel to hold a voltage that corresponds to the image, and applying the voltage to a liquid crystal LC. The gate driver circuit V includes a shift register SRT and dual gate driver TFTs for applying the voltage VGH, at which the pixel TFTs are turned on, to the gate lines GL connected thereto. In each gate driver TFT, a high voltage that turns the TFT on is applied to its gate GT for a period in which its connected gate line is selected. For example, during a period in which the n-th gate line Gn is selected, a high voltage equal to or higher than the voltage VGH is applied from a node Sout 1 of the shift register to the gate driver TFT that is connected to the gate line Gn. With the gate line Gn being selected, a high voltage is also applied to a node Sout 2 of the shift register that is connected to the drain of the gate driver TFT, and the voltage VGH is output to the source of the gate driver TFT. After writing in the pixel that is connected to the gate line Gn is finished, the node Sout 2 of the shift register is set to a low voltage, and the voltage VGL, at which the pixel TFT connected to the gate line Gn is turned off, is applied to the gate line Gn via the gate driver TFT. When the next stage gate line, namely, a gate line Gn+1, is selected, a low voltage is applied to the node Sout 1 to turn off the gate driver TFT connected to the preceding stage gate line Gn, and the gate driver TFT is kept turned off until the next time the gate line Gn is selected. The gate driver TFT is also connected at its source to a node Sout 3 of the shift register. During a period in which the gate line Gn is not selected, the voltage VGL for turning off the pixel TFT that is connected to the gate line Gn is output to the node Sout 3 . Similar voltage application is performed for the rest of the gate lines sequentially. The gate driver TFTs are required to charge and discharge the gate lines GL in a short period of time and, conventionally, would have needed to be large in size in order to provide a large driving power. In the liquid crystal display device of this embodiment, the TFT size can be reduced down to approximately half the conventional one by using a TFT that has an approximately twice larger driving power per unit area, while leakage in a pixel TFT is suppressed. This is accomplished by employing as a gate driver TFT a dual gate TFT that is high in mobility on the front side of the semiconductor film AS on the same substrate SUB 1 as the pixel TFT. In a gate driver circuit formed of amorphous silicon TFTs which are low in mobility, in particular, the size of gate driver TFTs determines the circuit width, and thus downsizing the TFTs in this part guarantees a reduction in circuit width. FIG. 3 is a plan view of a pixel which is formed on the TFT substrate side of the image display device according to this embodiment. FIG. 3 illustrates a so-called vertical electric field type liquid crystal display device in which the liquid crystal LC is held between a TFT substrate (corresponding to the substrate SUB 1 of FIG. 1 ) and a counter substrate (not shown) and driven with a voltage that is applied between the pixel electrode PX formed on the TFT substrate and a counter electrode (not shown) formed on the counter substrate. A pixel including a pixel TFT is formed on the TFT substrate side. The pixel TFT uses part of the gate line GL as the gate GT. As described above, the semiconductor film AS, which is made of amorphous silicon and has the low mobility layer on its front side, is formed above the gate GT. The semiconductor film AS is connected through the contact layer CN to the drain DT and the source ST. The drain DT is connected to the drain line DL and the source ST is connected to the storage capacitor C and the pixel electrode PX. A cross-sectional view taken along the line A-A′ of FIG. 3 corresponds to the left-hand side diagram of FIG. 1 , as described above. FIG. 4 is a plan view illustrating a gate driver TFT in the gate driver circuit V on the TFT substrate side of the image display device according to this embodiment. As described above, a cross-sectional view taken along the line B-B′ of FIG. 4 corresponds to the right-hand side diagram of FIG. 1 . FIG. 5 is a cross-sectional view taken along the line C-C′ of FIG. 4 . In the gate driver TFT, the first gate GT 1 is formed below the semiconductor film AS, which is made of amorphous silicon, with the first gate insulator film GI 1 interposed between AS and GT 1 , and the second gate GT 2 is formed in the opening OP of the passivation film PAS above the semiconductor film AS with the second gate insulator film GI 2 interposed between AS and GT 2 . No low mobility layer is formed on the semiconductor film AS. The second gate GT 2 is formed of a conductive film on the same layer as the transparent electrode which serves as the pixel electrode PX, and is connected to the node Sout 1 of the shift register SRT through a through hole TH 2 , which is formed in the passivation film PAS and in the second gate insulator film GI 2 . The first gate GT 1 is connected to the second gate GT 2 through a through hole TH 3 , which is formed in the passivation film PAS and in the first and second gate insulator films GI 1 and GI 2 . The drain DT of the gate driver TFT is connected to the node Sout 2 of the shift register SRT. The source ST of the gate driver TFT is connected to the node Sout 3 , and connected to the gate line GL through a conductive film on the same layer as the second gate GT 2 . FIGS. 6 to 11 are diagrams illustrating step by step an example of how the pixel TFT and gate driver TFT of FIG. 1 are manufactured. As in FIG. 1 , a manufacturing method for the pixel TFT is illustrated on the left-hand side of the diagrams and a manufacturing method for the gate driver TFT is illustrated on the right-hand side of the diagrams. First, in FIG. 6 , an Mo alloy is deposited by sputtering on a top surface of the substrate SUB 1 , which is made of, for example, glass, and the resultant film is processed by photolithography to form the gate GT of the pixel TFT, the capacitor line CL, and the first gate GT 1 of the gate driver TFT. Next, as illustrated in FIG. 7 , the first gate insulator film GI 1 , which is made of, for example, SiN, the semiconductor film AS, which is made of amorphous silicon, and the contact layer CN, which is an n + Si film made of phosphorus-containing amorphous silicon, are sequentially formed by plasma CVD. The semiconductor film and the contact layer are subsequently processed by photolithography to have a shape illustrated in FIG. 7 . Next, as illustrated in FIG. 8 , a three-layer metal film MT in which an Al alloy layer is sandwiched between Mo alloy layers is formed by deposition through sputtering. The metal film MT is processed by photolithography to form the source ST and drain DT of the pixel TFT and source ST and drain DT of the gate driver TFT. The contact layer CN is etched with resist (not shown) that is used for the processing of the drains DT and the sources ST being used as a mask. Part of the semiconductor film is also etched during the etching of the contact layer CN. As illustrated in FIG. 9 , a photoresist film RST is then used to form a resist pattern that covers the gate driver TFT side while exposing the pixel TFT side. With the photoresist film RST being used as a mask, a front side (exposed surface between the drain DT and the source ST) of the semiconductor film AS of the pixel TFT is irradiated with, for example, hydrogen plasma to form the low mobility layer LML. Next, as illustrated in FIG. 10 , the second gate insulator film GI 2 , which is made of, for example, SiN, is formed by plasma CVD, and subsequently processed by photolithography to form in the pixel TFT a through hole TH 1 ′, which is provided for connecting with the pixel electrode PX. Thereafter, as illustrated in FIG. 11 , a photosensitive transparent organic material capable of reducing a capacitance between the pixel electrode and a wiring line is applied to form the passivation film PAS. The passivation film PAS is exposed to light and developed, to thereby form the through hole TH 1 on the pixel TFT side. The through hole TH 1 is formed to be concentric with the through hole TH 1 ′, which has been formed in the second gate insulator film GI 2 . On the gate driver TFT side, the opening OP is formed to make the space above the semiconductor film AS open. Lastly, indium-tin-oxide (ITO) is deposited by sputtering to form a transparent electrode, which is processed by photolithography into the pixel electrode PX and the second gate GT 2 . The pixel TFT and the gate driver TFT structured as illustrated in FIG. 1 are thus obtained. This embodiment uses hydrogen plasma treatment to form the low mobility layer LML. However, other methods including He plasma treatment and Ar plasma treatment may be employed instead. FIG. 12 is a cross-sectional view illustrating a pixel TFT and a gate driver TFT according to a second embodiment of the present invention, and is drawn in a corresponding manner to FIG. 1 . The pixel TFT has, as in FIG. 1 , the low mobility layer LML formed on the front side of the semiconductor film AS. The semiconductor film AS is formed thinner in regions that are not covered with the source ST and drain DT of the gate driver TFT than in regions that are not covered with the source ST and drain ST of the pixel TFT, and a part of the semiconductor film AS of the gate driver TFT including the low mobility layer that is formed temporarily in the process of this embodiment is removed. Also in this embodiment, the mobility on the front side of the semiconductor film AS of the gate driver TFT is higher than the mobility on the front side of the semiconductor film AS of the pixel TFT, and the gate driver TFT which is a dual gate TFT having a large driving power and the pixel TFT that is reduced in leakage can be formed on the same substrate SUB 1 . FIGS. 13 and 14 each illustrate one of manufacturing steps for the pixel TFT and gate driver TFT of FIG. 12 . After the same steps as those described above with reference to FIGS. 6 to 8 are performed, plasma treatment is performed to form the low mobility layer LML on an entire surface of the semiconductor film AS. A low mobility layer is thus formed on the exposed front side of the semiconductor film AS in the pixel TFT and the gate driver TFT, whereby a structure illustrated in FIG. 13 is obtained. Subsequently, as illustrated in FIG. 14 , the photoresist RST that covers the pixel TFT and exposes the gate driver TFT is formed to etch the low mobility layer LML on the front side of the semiconductor film AS of the gate driver TFT. At this point, part of the semiconductor film AS is also etched, and a surface that is higher in mobility than the low mobility layer LML is formed as a result of the etching. In this embodiment, for example, the semiconductor film AS and the contact layer CN are formed to 200 nm and 30 nm, respectively, and, in the step of FIG. 8 , the contact layer CN is removed and 50 nm of the semiconductor film AS is etched away to make the thickness of the semiconductor film AS be 150 nm in regions that are not covered with the source ST and the drain DT. The low mobility layer LML is formed to 20 nm or so, for example. As illustrated in FIG. 14 , the semiconductor film AS including the low mobility layer LML is etched further by 50 nm, whereby the thickness of the semiconductor film AS of the gate driver TFT is 100 nm in regions that are not covered with the source ST and the drain DT. Next, the same steps as those of FIGS. 10 and 11 are performed to obtain a structure illustrated in FIG. 12 . In this embodiment, the semiconductor film AS is made thin and accordingly reduced in total count of defects within the film. Therefore, there is an advantage that a lower voltage is required to drive a gate driver TFT. FIGS. 15 and 16 are diagrams illustrating a method of manufacturing a pixel TFT and a gate driver TFT according to a third embodiment of the present invention, and each illustrate one of manufacturing steps for the pixel TFT and the gate driver TFT. After the structure described above with reference to FIG. 7 is formed, the three-layer metal film MT made up of a Mo alloy layer and Al alloy layers is formed by deposition through sputtering as in the above description. As illustrated in FIG. 15 , photoresist RST 1 is formed for processing with which the source ST and drain DT of the pixel TFT are formed while a region that is to become the gate driver TFT is covered. The metal film MT is etched in this state. The exposed part of the contact layer CN and part of the semiconductor film AS are also etched, and then plasma treatment is performed to form the low mobility layer LML on the front side of the semiconductor film AS of the pixel TFT. Next, as illustrated in FIG. 16 , the photoresist RST 1 is removed and then photolithography process is performed again to form photoresist RST 2 , which covers the pixel TFT in order to form the source ST and drain DT of the gate driver TFT. Thereafter, the metal film MT, the contact layer CN, and part of the semiconductor film AS are etched, and the steps of FIG. 10 and subsequent steps are executed. A structure that makes the mobility on the front side of the semiconductor film of the gate driver TFT larger than the mobility on the front side of the semiconductor film of the pixel TFT is thus obtained. In this embodiment, the semiconductor film AS of the pixel TFT and the semiconductor film AS of the gate driver TFT are etched independently of each other. This embodiment can therefore improve characteristics in the same manner as in FIG. 12 , in which the semiconductor film AS of the gate driver TFT is made thinner in regions that are not covered with the source ST and the drain DT than the semiconductor film AS of the pixel TFT formed in regions that are not covered with the source ST and the drain DT. In addition, the semiconductor film AS of the pixel TFT and semiconductor film AS of the gate driver TFT are each etched only once in regions that are not covered with the source ST and the drain DT. This gives the third embodiment an advantage of improved precision with respect to the thickness of the semiconductor film AS over the case of FIGS. 13 and 14 , in which the gate driver TFT is etched a plurality of times. The same advantage is obtained also when this embodiment is reversed by forming the source ST and drain DT of the gate driver TFT first with the use of a resist pattern that covers a region allocated to the pixel TFT, and then forming the source ST and drain DT of the pixel TFT as well as a low mobility layer on the front side of the semiconductor film AS of the pixel TFT, with the use of a resist pattern that covers the gate driver TFT. FIG. 17 illustrates an example of an equivalent circuit of a horizontal electric field type (in-plane-switching type) liquid crystal display device according to a fourth embodiment of the present invention, and is drawn in a corresponding manner to FIG. 2 . As in FIG. 2 , a pixel and the gate driver circuit V which are formed of TFTs are formed on the same substrate SUB 1 . In the horizontal electric field type liquid crystal display device, the pixel electrode PX and a counter electrode CT are both formed on the TFT substrate SUB 1 side. A voltage applied to the counter electrode CT through a counter voltage line CTL serves as a reference for a voltage applied to the pixel electrode PX. A storage capacitor is formed between the pixel electrode PX and the counter electrode CT. A pixel TFT is formed in the pixel PIX. The low mobility layer LML is formed on the front side of the semiconductor film AS of the pixel TFT. A gate driver TFT of dual gate type is formed in the gate driver circuit V to control the gate line GL with an output from the shift register SRT. No low mobility layer is formed on the front side of the semiconductor film AS of the gate driver TFT, and the mobility on the front side of the semiconductor film AS of the gate driver TFT is higher than the mobility on the front side of the semiconductor film AS of the pixel TFT. The node Sout 1 of the shift register SRT is connected to the lower gate GT 1 and upper gate GT 2 of the gate driver TFT. A capacitor Cgd is formed between the Sout 1 and the drain DT of the gate driver TFT. The capacitor Cgd has a function of holding a voltage that is output from Sout 1 . For example, when a gate line Gn−1 is selected, the high voltage VGH is applied from Sout 1 to the lower and upper gates GT 1 and GT 2 of the gate driver TFT that is connected to the next stage gate line, namely, the gate line Gn, and the low voltage VGL is applied to the drain line DL, whereby a potential difference VGH−VGL is held in the capacitor Cgd. When the gate line Gn is selected subsequently, the node Sout 1 is set to a floating potential, and the high voltage VGH is applied to the node Sout 2 . At this point, owing to the capacitor Cgd, a voltage equal to or higher than VGH is applied from the node Sout 2 to the lower and upper gates GT 1 and GT 2 of the gate driver TFT, and the high voltage VGH is applied to the gate line GL connected to the source ST. This method does not need to apply a voltage equal to or higher than VGH to the node Sout 2 , and therefore has an advantage that the same voltage as when a supply voltage circuit is not built in can be used. The method, however, requires an area for forming the capacitor Cgd. FIG. 18 is a cross-sectional view of the pixel TFT and the gate driver TFT illustrated in FIG. 17 , and is drawn in a corresponding manner to FIG. 1 . The pixel TFT is illustrated in cross section on the left-hand side of FIG. 18 , and the cross-sectional view thereof corresponds to a view taken along the line D-D′ of FIG. 19 which is described later. The gate driver TFT is illustrated in cross section on the right-hand side of FIG. 18 , and the cross-sectional view thereof corresponds to a view taken along the line E-E′ of FIG. 20 which is described later. In FIG. 18 , the low mobility layer LML is also formed on the front side of the semiconductor film AS of the pixel TFT, which is formed in each pixel, to thereby suppress leakage due to an electric field from the passivation film PAS and the counter electrode CT above the TFT. The gate driver TFT is a dual gate TFT having the first gate GT 1 , which is formed of a metal film on the same layer as the gate GT of the pixel TFT, and the second gate GT 2 , which is formed of a transparent conductive film on the same layer as the counter electrode CT. The semiconductor film AS is formed above the first gate GT 1 with the first gate insulator film GI 1 interposed between AS and GT 1 . No low mobility layer is formed on the front side of this semiconductor film AS, which enables the second gate GT 2 to improve the driving power of the gate driver TFT. The second gate GT 2 has a region in the opening OP of the passivation film PAS which faces the semiconductor film AS with the second gate insulator film GI 2 , which is formed on the source ST and the drain DT, interposed between AS and GT 2 . The capacitor Cgd is formed between the drain DT and the first gate GT 1 with the first gate insulator film GI 1 interposed between DT and GT 1 . Another capacitor Cgd is formed between the drain DT and the second gate GT 2 with the second gate insulator film GI 2 interposed between DT and GT 2 . In the fourth embodiment, the capacitor Cgd is formed between the second gate GT 2 and the drain DT in addition to between the first gate GT 1 and the drain DT, and the capacitance per unit area is increased. Therefore, a smaller area is required to form capacitors. This gives the fourth embodiment an advantage that the circuit width is reduced. Further, the pixel electrode PX and the counter electrode CT in the fourth embodiment can both be formed of, for example, an ITO film which is a transparent conductive film. The source ST and the drain DT can be formed of a single-layer metal film that has a high melting point and that is capable of forming a solid contact with n + Si and ITO, for example, a film of Cr, Mo, or W, or an alloy thereof. The first and second gate insulator films GI 1 and GI 2 and a capacitor insulator film IN can be formed of a SiN film formed by plasma CVD. Through steps substantially the same as those illustrated in FIGS. 6 to 11 (or FIGS. 13 and 14 ), the semiconductor film AS is formed so that the mobility on the front side of the semiconductor film AS of the gate driver TFT is higher than the mobility on the front side of the semiconductor film AS of the pixel TFT. FIG. 19 is a plan view of the pixel part of the TFT substrate of the horizontal electric field type liquid crystal display device which includes the pixel TFT illustrated in FIG. 18 . As described above, a cross-sectional view taken along the line D-D′ of FIG. 19 is the cross-sectional view on the left-hand side of FIG. 18 . Also in the horizontal electric field type liquid crystal display device, a liquid crystal is held between the TFT substrate SUB 1 and the counter substrate (not shown). An electric field is generated between the pixel electrode PX and the counter electrode CT, which are formed on the TFT substrate SUB 1 side, and is applied to the liquid crystal to display an image. The pixel electrode PX has a comb-teeth shape in order to apply an in-plane direction electric field to the liquid crystal. The pixel electrode PX, together with the counter electrode CT which is formed below the pixel electrode PX, generates an electric field for driving the liquid crystal. A storage capacitor is formed between the pixel electrode PX and the counter electrode CT, with the capacitor insulator film IN interposed between PX and CT. The pixel electrode PX is connected to the source ST of the pixel TFT through an opening that is formed in the second gate insulator film GI 2 , the passivation film PAS, the counter electrode CT, and the capacitor insulator film IN. The gate GT and drain DT of the pixel TFT are connected to the gate line GL and the drain line DL, respectively. FIG. 20 is a plan view of the gate driver circuit part of the TFT substrate which includes the gate driver TFT illustrated in FIG. 18 . As described above, a cross-sectional view taken along the line E-E′ of FIG. 20 is the right-hand side diagram of FIG. 18 . FIG. 21 is a cross-sectional view taken along the line F-F′ of FIG. 20 . In the gate driver TFT, the first gate GT 1 is formed below the semiconductor film AS, which is made of amorphous silicon, with the first gate insulator film GI 1 interposed between AS and GT 1 , and the second gate GT 2 is formed in the opening OP of the passivation film PAS, which is formed above the semiconductor film AS and the drain DT, with the second gate insulator film GI 2 interposed between AS and GT 2 . No low mobility layer is formed above the semiconductor film AS of the gate driver TFT. The second gate GT 2 is formed of a conductive film on the same layer as the transparent electrode that serves as the counter electrode CT, and is connected to the node Sout 1 of the shift register SRT through the through hole TH 2 , which is formed in the passivation film PAS and in the second gate insulator film GI 2 . The first gate GT 1 is connected to the second gate GT 2 through the through hole TH 3 , which is formed in the passivation film PAS and in the first and second gate insulator films GI 1 and GI 2 . The drain DT of the gate driver TFT is connected to the node Sout 2 of the shift register SRT. A capacitor is formed below the drain DT and between the drain DT and the first gate GT 1 , with the first gate insulator film GI 1 interposed between DT and GT 1 . In the opening OP of the passivation film PAS, another capacitor is formed between the second gate GT 2 and the drain DT, with the second gate insulator film GI 2 interposed between GT 2 and DT. The capacitors together function as the capacitor Cdg. The source ST of the gate driver TFT is connected to the node Sout 3 , and connected to the gate line GL through a conductive film on the same layer as the second gate GT 2 . Also in the fourth embodiment, the mobility on the front side of the semiconductor film AS of the gate driver TFT is made higher than the mobility on the front side of the semiconductor film AS of the pixel TFT. Therefore, there is obtained an effect of reducing the TFT size and accordingly reducing the circuit width by increasing the driving power that is provided by the upper gate GT 2 of the gate driver TFT, while suppressing leakage in the pixel TFT. The fourth embodiment uses a transparent conductive film on the same layer as the counter electrode CT to form the second gate GT 2 of the gate driver TFT. A transparent conductive film on the same layer as the pixel electrode PX may be employed instead. In this case, the second gate insulator film GI 2 may be omitted by replacing GI 2 with the capacitor insulator film IN as an insulator film between the second gate GT 2 and the semiconductor film AS. The structure of the second gate GT 2 and the second gate insulator film GI 2 may be modified to suit individual cases as long as the pixel TFT and the gate driver TFT maintain their magnitude relation about the mobility on the front side of the semiconductor film AS. While there have been described what are at present considered to be certain embodiments of the invention, it will be understood that various modifications may be made thereto, and it is intended that the appended claims cover all such modifications as fall within the true spirit and scope of the invention.

Provided is an image display device comprising, on a TFT substrate: a plurality of gate lines and a plurality of drain lines which intersect with each other; a pixel TFT provided within a pixel which is enclosed by a pair of adjacent gate lines and a pair of adjacent drain lines; a gate driver TFT which is connected to one of the plurality of gate lines to drive the one of the plurality of gate lines, wherein the pixel TFT and the gate driver TFT each include an amorphous semiconductor film as a channel, wherein the pixel TFT has a bottom gate structure, wherein the gate driver TFT has a dual gate structure, and wherein a mobility on a top surface side of the semiconductor film of the gate driver TFT is higher than a mobility on a top surface side of the semiconductor film of the pixel TFT.

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to and it a continuation of application Ser. No. 12/627,749, which was filed Nov. 30, 2009, which is a division of application Ser. No. 12/236,651, filed Sep. 24, 2008, now abandoned, which is a Continuation of application Ser. No. 09/480,991, filed Jan. 11, 2000, now U.S. Pat. No. 7,430,533, which issued Sep. 30, 2008, the entire contents of which are hereby incorporated by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] This invention relates generally to securities markets. Particularly, the invention relates to a system and method for batch auctions which are designed to occur at preset times. This can facilitate securities trading particularly either preceding or following periods of trade stoppage or inactivity. [0004] 2. Description of the Related Art [0005] A securities trading mechanism can be thought of as a set of protocols that translate the investors' latent demands into realized prices and quantities. The trading mechanism employed at market opening represents the first opportunity to trade after the overnight or weekend non-trading period. Market openings are often characterized by uncertainty over fundamentals, such as share volume and price, and the presence of multiple potential trading parties. For this reason, opening protocols play an especially important role in facilitating “price discovery,” or the price which will maximize the number of trades at the resumption of trading in securities markets. [0006] The closing or halting of trading on securities markets also is important because closing stock prices are widely used as benchmarks of the securities' values. Portfolio returns and mutual fund net asset values are computed using closing prices. Additionally, after-hours trading on various alternative trading systems (“ATS”) and electronic communications networks (“ECNs”) are based on prices of stocks at closing. Thus, large trading volumes often occur near the end of the trading day which has led to concerns regarding price stability and the ability of the markets to provide adequate liquidity. [0007] Thus, it is desirable to have a method or system for facilitating price discovery and providing liquidity in securities markets at the opening and closing of trading as well as during the course of trading throughout the day. [0008] Securities markets have recognized a need to use special protocols to open trading at the start of the day or following periods of non-trading, or to close trading at the end of the day. Opening protocols employed in some securities markets play an especially important role in facilitating price discovery following the enforced trading halt induced by the overnight or weekend non-trading period. Thus, various attempts have been made by markets to introduce special opening procedures designed to provide traders with information regarding market clearing prices with a view towards enhancing liquidity and reducing intra-day price volatility. [0009] The protocols employed vary greatly in significant ways. By way of example, some markets, such as the New York Stock Exchange (“NYSE”) are intermediated and rely on designated dealers, market makers and specialists, to select opening prices. Other markets simply rely on accumulated overnight public limit orders to calculate mathematically an equilibrium price at which to open trading. Markets also vary widely with respect to the amount of transparency they provide to investors. For example, in the Paris Bourse, traders obtain a sequence of indicated prices prior to the opening which reflects the current market clearing prices, and are allowed to revise their orders based upon this information. In other markets, only limited pre-open price and volume information can be observed at the time orders are submitted. [0010] Most securities markets, with the notable exception of Nasdaq, therefore use special protocols such as single-price batch auctions to open and close their markets. Similarly, single-price auctions are often used as the blueprint for new, automated trading systems such as that disclosed by U.S. Pat. No. 5,873,071 to Ferstenberg et al. and the system in use by the Arizona Stock Exchange (“AZX”). The prior art approaches employed during market openings and closings, and the protocols followed during batch auctions in general vary significantly. [0011] On the NYSE, special protocols apply to the market opening each morning and following periods of suspended trading. As depicted in FIG. 1 , the NYSE conducts an “intermediated open” whereby market orders 1 and limit orders 2 accumulate in the limit order book 3 overnight and are reviewed by an intermediary, the specialist, prior to opening. The specialist then uses his or her knowledge regarding the order book and market conditions to set or stabilize security opening price 6 by offsetting large trade imbalances (by personally buying or selling or allowing other floor traders to buy or sell the security as necessary). This system has the inherent drawback in that the specialist has goals which work against accurate price discovery: to provide price continuity, and to maintain a desired inventory of the security. Thus, the price at opening often does not accurately reflect the price dictated by market supply and demand. [0012] The Nasdaq, conversely, currently employs no differentiated opening protocol. During a period prior to the opening of continuous trading on the Nasdaq, market makers and ECNs can enter non-binding price quotes which are broadcast to market subscribers. Although these quotes can be modified at any time prior to the open, they are made to provide a mechanism for dealers to share information and coordinate their pricing decisions. These quotes, however, are at no point binding such that the market makers are under no obligation to execute trades at the quoted price. There are a number of related drawbacks to such a non-differentiated opening. First, there is significant price volatility as accumulated overnight orders are executed in an uncoordinated burst in the first few minutes after the start of trading. This volatility in turn provides an increased potential for price manipulation. [0013] The Paris Bourse and Toronto Stock Exchange (“TSE”) operate as continuous limit order markets. The TSE, unlike Paris, employs a designated intermediary, termed the Registered Trader, for each stock who is responsible for maintaining the limit order book. The TSE is transparent as it displays the order book and disseminates an indicated price, the calculated opening price (“COP”), based upon current system orders. The COP is continuously updated based upon new orders and fluctuations in relative supply and demand. To discourage gaming by traders the TSE has implemented anti-scooping rules whereby non-client orders entered within the final two minutes before opening are figured into the COP, and thus guaranteed a fill at the COP, only if they impact the COP. Non-client orders not impacting the COP are not guaranteed a fill at the COP, and are automatically treated by the TSE as the equivalent of a limit order having a price equal to the COP. In the event that there is a “guaranteed fill imbalance” (not all guaranteed orders can be filled by matching orders due to order imbalance), the Registered Trader is required to either provide the requisite liquidity at the COP, or to delay the opening until sufficient orders offsetting the imbalance enters the TSE. Additionally, orders having a price equal to the COP (such as a market order) are allocated executed shares only after all market orders and orders having prices better than the COP are filled. Thus, the priority and allocation rules of the TSE system gives it the inherent drawback in that limit orders at a price equal to the COP can get frozen out of the trading process and are not treated the same as market orders and better priced limit orders. Furthermore, if there are no intersecting limit orders for a particular security, no COP is calculated and no limit orders are executed. [0014] In the Paris Bourse, a similar batch auction system is employed except that traders can observe the limit order book away from the current price. This high degree of transparency allows traders to assess the likely impact on the opening price of new orders, but similarly encourages gaming as orders may be readily canceled up to the open. Furthermore, there is no designated intermediary to provide liquidity when there is an order imbalance. The Paris Bourse also has introduced a closing call auction using similar priority, cancellation, and transparency parameters. This system suffers from several drawbacks, including: significant gaming incentives, price instability, and no guaranteed liquidity. [0015] The Arizona Stock Exchange (“AZX”) operates solely in a batch auction market format. Thus, its open (the first trade of the day) and its close (the last trade) do not have protocols which differ from other trades during the day. Like the Paris Bourse, the AZX has a high degree of transparency in that traders are permitted to see the entire order book prior to an auction and can view beforehand the exact price at which trades would occur. This again leads to gaming which prevents accurate price formation. [0016] The OptiMark electronic trading system employed by the Pacific Stock Exchange (“PSE”) conducts repeated batch auctions over the course of a market day similar in manner to the AZX, but offers less transparency and generates multiple prices such that all trades of a particular stock during a given auction are not made at the same price. [0017] U.S. Pat. No. 5,950,176 to Keiser et al. discloses an electronic securities trading system which uses a computer program to project price movement of securities and set suggested prices for trading in continuous trading markets. This system does not solve the problems attendant in batch auction methods and systems where providing optimal price determination is hampered by gaming and low liquidity. [0018] The prior art approaches to using batch auctions at the open and close of a financial market, as well as repeatedly throughout the market day along with continuous trading, have encountered numerous drawbacks. Open order books combined with lack of restrictions on the message space prior to the open introduce gaming problems, for example as experienced by traders in the Paris Bourse. The existence of multiple order books with different levels of transparency and different execution priority rules, as used by the AZX, produce undesirable disparities in fill rates. An additional drawback is that simple batch auction design is not sufficient to produce accurate pricing in low liquidity, high volatility markets as is present for thinly traded stocks. Further, intermediated exchanges depending upon human intervention, such as by specialists on the NYSE and TSE, introduce exterior forces upon market price determination, such as the specialists' inventory concerns. Additionally, price discrimination among traders within a single auction based upon their order types, as done by the PSE OptiMark system, can cause dissatisfaction among participating traders with the outcome produced by the auction system. [0019] Due to the above mentioned and other drawbacks, there remains a need in the art for improved methods and systems to conduct batch auctions of financial securities in financial markets, particularly both following and preceding periods of trade stoppage or inactivity. SUMMARY OF THE INVENTION [0020] Therefore, it is an object of the present invention to provide a method and system for performing securities transactions via a batch auction, whereby the system is incentive compatible in the sense that traders do not have the incentives to game or manipulate the order messages they send to the system. [0021] It is also an object of the present invention to provide a method and system for performing batch auctions of securities which is particularly suited to being conducted either directly preceding or directly following a trade stoppage or period of inactivity. [0022] Further, it is an object of the invention to provide a method and system for performing such transactions which is computationally feasible, and therefore lends itself to broad-based electronic implementation. [0023] Additionally, it is an object of the present invention to provide a method and system for performing such transactions which provides accurate pricing information. [0024] Finally, it is an object of the present invention to provide a method and system for conducting batch or call auctions having allocations for participation by a market-making intermediary. [0025] The present invention provides a method and system for gathering orders from qualified market participants, determining (or “discovering”) a price and share quantity based on the aggregate supply and demand represented by all orders submitted, executing the resulting quantity, and “fairly” allocating the executed shares back to the submitters of the orders. The method and system can be advantageously used to periodically initiate (“open”) and terminate (“close”) trading in financial instruments as well as to operate concurrent with “continuous” trading systems, such as the “continuous auction” operated by the NYSE and by electronic trading on Nasdaq and in ECNs. Financial instruments according to the present invention include stocks, bonds, commodities, options, futures contracts, pollution rights and other tangible and intangible goods. A full iteration of the system, comprised sequentially of an order acceptance period, a price discovery period, and an order execution period, is referred to as an “auction cycle”. Auction cycles according to the present invention operate at pre-determined times that are known to qualified auction participants, such as (but not limited to) traders. [0026] In general, the markets that have recognized the special nature of trades performed either at market openings or market closings have instituted specialized, or differentiated, protocols for trades occurring at these times. Commonly, these special protocols have come in the form of a call or batch auction. Each iteration of a batch auction (or an “auction cycle”) is typified in that a series of investors simultaneously trade, i.e., buy or sell, a stock at a single price. [0027] In determining the protocols and rules for the batch auction mechanism of the present invention, a series of parameters must be taken into consideration. The first is in regard to transparency and informational parity. The rules adopted regarding these parameters reflect the decision as to what extent each trader participating in the auction can have access to information detailing the buy and sell orders of other traders, the “limit order book,” and how it impacts on the amount of “gaming” occurring in the market and perceived marked reliability. A second and related parameter is whether orders may be made and then later canceled or modified. The ability to modify or cancel, like the presence of excess transparency and complete informational parity, may lead to increased gaming by traders. Additionally, rules have to be established regarding a third parameter which is priority of trade orders in the event that there is an imbalance in supply or demand. Finally, a fourth parameter reflects the decision as to whether intermediation will be employed (as is done on the NYSE and TSE with specialists), and to what extent such intermediation will require participation by a designated market maker. [0028] One aspect of the invention comprises a method for performing a batch auction whereby a series of orders, according to a variety of predetermined order types, are generated by qualified market participants and communicated to the auction system. The system takes into account each order and its impact upon relative supply and demand. For each security in question, bids and offers are crossed to determine by a preset algorithm a “discovered” price and share transaction quantity. Trades are executed, and a portion of the transaction quantity is allocated to each investor on a fair basis dependent upon their initial orders. [0029] In preferred embodiments of the present invention, the auction method is performed using a computer system or network designed to automatically perform one or more steps of the method. Qualified market participants therefore may submit orders to the auction system electronically whereby the orders are then stored in a computer database until such time as the orders are modified or canceled by the submitting participant or until commencement of the price discovery period. During the price discovery period, orders received during the order acceptance period are crossed according to a present price discovery algorithm being performed by a computer. Using the algorithm, the computer identifies an optimal price and allocation of trades. These trades are then executed at the optimal price and returned to the qualified participant during the subsequent order execution period. [0030] Another embodiment of the present invention comprises an electronic system for conducting batch auctions of securities. Such a system can be comprised of a computer network designed to accept a plurality of orders from a variety of sources. At a predetermined time, all current orders are crossed according to a preset algorithm to determine a share price and quantity for each security being traded. A trade of shares in an amount equal to the quantity is automatically executed by the system, and then fairly allocated to each order source. Such a system is preferably connected to one or more ECNs such that non-executed shares can be automatically sent to outside sources for execution and to ensure compliance with “trade-through” rules. [0031] In alternative embodiments, the invention includes the use of an intermediary or market maker. Such an intermediary would have access to otherwise confidential information of the limit order book in exchange for a guarantee to cover certain unexecuted trades at the discovered price. [0032] The present invention will become more fully understood from the forthcoming detailed description of preferred embodiments read in conjunction with the accompanying drawings. Both the detailed description and the drawings are given by way of illustration only, and are not limitative of the present invention as claimed. BRIEF DESCRIPTION OF THE DRAWINGS [0033] FIG. 1 is a schematic diagram of the interaction between an intermediary and several types of market participants according to a prior art mechanism. [0034] FIG. 2 is a flow chart depicting the algorithm whereby new and modified orders are handled during the order acceptance period in embodiments of the present invention. [0035] FIG. 3 is a flow chart depicting the algorithm whereby an optimal price is discovered during the price discovery period in embodiments of the present invention. [0036] FIG. 4 is a schematic diagram demonstrating the interaction of various factors during operation of a preferred embodiment of the present invention. [0037] FIG. 5 is a schematic diagram of a preferred embodiment of the present invention wherein an intermediary is employed. DETAILED DESCRIPTION OF THE INVENTION [0038] A batch auction cycle of the present invention is comprised of three sequential periods: an order acceptance period, a price discovery period, and an order execution period. During the order acceptance period, the system accepts orders from qualified participants. The definition of a qualified participant will vary as is known in the art depending on how the system is implemented, as well as on the types of financial instruments traded and the country in which it is operated. This definition will often depend on whether the system is implemented as a facility of an established market or exchange. In this case, who are deemed qualified participants will likely be defined or limited by the exchange's rules. [0039] Each order submitted essentially represents the bounds, as defined by the order-submitting trader, within which a purchase/sale of a particular security is desired. All orders generally are comprised of a trade “side” (buy or sell), a security identifier (such as the name or symbol of the security), and a quantity. In embodiments of the present invention, a variety of order types can be used by traders to more thoroughly describe the conditions under which they desire to trade. [0040] A first order type is an “unpriced order.” The submission of an unpriced order to the system identifies a desire by the submitter to participate in the auction at whatever price is discovered (if any) during the later price discovery period. An unpriced order for a given auction cycle is fully specified by the above three basic elements: a security identifier, an order quantity, and a trade side. [0041] Optionally, a maximum (minimum) acceptable transaction price can be specified in an unpriced buy (sell) order (“I will not sell for less than $100.00 per share”). This price, however, will not influence the price discovery algorithm as it is described below with respect to the price discovery period. [0042] Another order type which can be submitted to the system is the “priced order.” Priced orders are fully specified by four elements: security identifier, order quantity, trade side (i.e. buy or sell) and a desired price. This desired price represents an offer by the trader (e.g., “I will sell X shares for $100.00 per share”), and is used during the price discovery period, described in detail below, to determine the price at which the auction will take place. At the user's option, any unexecuted shares (due to a mismatch in buy and sell orders) of a priced order after the order execution period can be automatically forwarded to another (“secondary”) destination at the end of the auction cycle. While not all destinations will necessarily be supported, the user will be able to choose among supported destinations. Where practical, support for unique order attributes of a particular secondary destination, such as “reserve quantity,” or “pegging”, etc., will be provided. [0043] In preferred embodiments of the present invention, the supplied price stated in priced orders may be supplied in terms of the quoted market for the underlying security, such as equal to the bid, offer, or the mid-point of the bid-offer spread. Alternatively, the supplied price can be made dependent upon fluctuations in the known market indicators (futures price movement) and indices (the S&P 500) occurring between the time the order is submitted and the time the auction begins. [0044] A third type of order which may be submitted according to embodiments of the present invention is the “cross order.” A cross order is similar to an unpriced order in that it contains quantity and trade side terms, but is distinguished in that two sides (both buy and sell) of a transaction are submitted to the system as a unit to be crossed at the discovered price. Such an order type is essentially a tool to allow large blocks of shares of a particular stock to quickly be traded between two traders at a market determined price (the discovered price). The opposing sides of a cross order cannot be broken up. If no price is discovered by the execution of priced orders within that particular auction cycle, cross orders will have the option of being returned unexecuted, being held over for the next auction cycle, or being crossed at a reference price that will be computed as part of the auction process. A suitable algorithm for determining both a discovered price and a reference price is described in detail below. [0045] As described above, the amount of transparency present during a batch auction cycle for trading securities is of major concern. A balance must be struck regarding the extent of information regarding other traders' orders which should be supplied during the order acceptance period to each trader participating in the particular auction cycle. If each potential trader has full access to information detailing the buy and sell orders of other traders, known as the “limit order book,” an incentive is placed upon traders to try and affect discovered price to their liking by altering their order parameters. The extent of such practice, known as gaming, within the auction system can lead to perceived unreliability. [0046] The system of the present invention provides partial transparency during the order acceptance period of the auction cycle. Specifically, two pieces of information are disseminated continuously in the first of two stages comprising the order acceptance period: an “indicated price” and a “net order imbalance.” As each new order is received, the indicated price and net order imbalance is recalculated and disseminated to qualified participants. The indicated price is defined as the price at which an auction would occur if it were to take place at that moment, and is calculated according to the price discovery algorithm detailed below. The net order imbalance is the excess supply or demand in the financial instrument being auctioned (i.e. 1500 surplus shares bid). If there are no intersecting orders (i.e., no possible trades), then “N/A” will be disseminated for the net surplus. At a minimum this information will be made available to some or all qualified participants. Preferably, this information will be made available via market data services and other real-time information providers. [0047] At any time during the first stage of the order acceptance period, any qualified participant may cancel or modify any order they have previously placed during that particular auction cycle. However, the ability to modify or cancel orders, especially when combined with transparency, provide incentives for traders to participate in gaming. [0048] To limit this gaming incentive, the present invention employs an order acceptance algorithm. According to this algorithm, qualified participants who have submitted an order will not be allowed to cancel, reduce the quantity of, or make the price less aggressive than previously placed orders within a specified time window (the “order entry cut-off window”) prior to the beginning of the price discovery period. (Modified orders seeking to increase quantity or make the price more aggressive are treated like a new order having the attributes of the order as modified.) This window just prior to the beginning of the price discovery period constitutes the second stage of the order acceptance period. New orders will not be accepted automatically during this stage as they were in the first stage. Such second stage orders will be accepted only to the extent that they offset a published net order imbalance. Thus, buy (sell) orders for a given security will only be accepted if there is an excess supply (demand). Furthermore, the size of any such new second stage order may not exceed the then-current size of the net order imbalance. With respect to new second stage priced orders, the order price must be at least as aggressive (greater than or equal to for bids, less than or equal to for offers) as the then-current indicated price in order to be accepted. [0049] Referring to FIG. 2 , an exemplary order acceptance algorithm, preferably performed by a computerized system using software, according to one embodiment of the present invention receives an order request 100 and first makes a determination at 101 as to whether the order request constitutes a new order 101 a or a modification 101 b . The system screens the new order at 102 and makes a determination as to whether it was submitted during the first or second stage of the order receiving period. If the new order was received during the first stage 102 a , then this order automatically gets entered into the limit order book 103 . [0050] If the new order was received during the second stage 102 b , the system then screens the order at 104 and 106 to determine if it would offset a current net order imbalance, and if the price is at least as aggressive as the current indicated price. If the new order satisfies both criteria, then the new order still would be entered into the order book 103 as shown by paths 104 a and 106 a in the figure. If the new order fails to meet either of these criteria 104 and 106 , the order is rejected as late and not entered into the limit order book 105 as shown by paths 104 b and 106 b. [0051] In the event that the order request received at 100 is found not to be a new order at 101 , but instead a modification or cancellation 101 b of an order already in the order book, a different set of anti-gaming rules apply. If at 107 the system finds that the modification or cancellation order was received in the first stage 107 a of the order receiving period, then the modification or cancellation order would be used to appropriately update the limit order book 108 . If at 107 the system finds that the modification or cancellation order request was received in the second stage 107 b of the order receiving period, then the system determines whether the request cancels a previous order 109 , reduces the quantity of a previous order 110 , or makes the price of a previous order less aggressive 111 . If the request does any of these three things, then the request is not permitted to update the order book 105 as seen by paths 109 a , 110 a , and 111 a . As shown by paths 109 b , 110 b , and 111 b , requests seeking to modify orders to increase quantity or make the price more aggressive only modify the limit order book 108 if, as with new orders received in the second stage, the request would offset 112 a a net order imbalance 112 . [0052] After the time window has elapsed and the second stage has ended, no order requests are accepted. The auction itself begins with the commencement of the price discovery period whereby buy and sell orders for each security are crossed at a discovered price. This discovered price is individually calculated for each auction cycle by the price discovery algorithm described in detail below and depicted by FIG. 3 , and represents a market optimal price at which to execute submitted orders. [0053] In the event of extreme market conditions, the pre-auction period of auction cycles of the present invention can be extended by successive pre-defined time intervals (e.g. five minutes). This time interval will be applied only to the first stage of order taking, and will in essence push back the window wherein the second stage occurs and push back the time at which the batch auction actually occurs. Preferably, rules will be established for automatic extensions on the basis of order imbalance and movements in certain broad market indexes (as defined and permitted by stock exchange rules and regulations, if any). A human operator in charge of monitoring the system also will have discretionary ability to invoke an extension. [0054] The price discovery algorithm employed during the price discovery period of auction cycles in embodiments of the present invention uses the information contained in priced orders in the limit order book for each auction cycle to calculate, based upon relative supply and demand, a discovered price. This is the price at which all trades of a given security will occur for that particular auction cycle. Preferably, the operation of the price discovery algorithm is automated, such as by software running on a computerized network. [0055] As depicted by FIG. 3 , a price discovery algorithm according to the present invention first operates by examining the limit order book 200 to identify a price 201 for a given security at which the volume of shares traded will be maximized. In the event that a single security price 202 , a “discrete” price, is identified which will cause a maximum amount of shares (from priced orders) to be executed, then that discrete price is identified as the discovered price 203 . Example 1 [0056] Buyer A enters a priced order offering to buy 10,000 shares for ½. [0057] Buyer B enters a priced order offering to buy 10,000 shares for ⅜. [0058] Seller X enters a priced order offering to sell 10,000 shares for ⅜. [0059] Seller Y enters a priced order offering to sell 10,000 shares for ⅜. [0060] At a price of ½, only A is willing to buy, thus only 10,000 shares would be executed. At a price of ⅜, 20,000 shares would be executed as both A and B are willing to buy 10,000 apiece while X and Y are willing to sell 10,000 apiece. Since there is a single volume maximizing price, the discovered price equals ⅜. [0061] The volume of unpriced orders will be included in the cumulative supply and demand of volume. For example, if there are 50,000 units of unpriced buy orders and 25,000 units of unpriced sell orders, these shares will be added to volume of priced buy and sell orders, respectively, at each price. If unpriced orders meet priced orders that do not intersect, these unpriced orders will cross at the volume-maximizing price with the corresponding priced orders. [0062] In the event that there are only unpriced buy and sell orders, the unpriced orders will trade at a predefined reference price. Example 2 [0063] Buyer A enters a priced order offering to buy 10,000 shares at a price of 50.00, and an unpriced order offering to buy 50,000 shares at the determined price. [0064] Buyer B enters a priced order offering to buy 5,000 shares at a price of 50.10. [0065] Seller X enters a priced order offering to sell 20,000 shares at a price of 50.30, and an unpriced order offering to sell 25,000 shares. [0066] Seller Y enters a priced order offering to sell 15,000 shares at a price of 50.20. [0067] Between A, B, X, and Y there are unpriced and non-intersecting priced buy and sell orders on for the particular auction cycle. At a price of 50.00, buyer A would be willing to buy a total of 60,000 shares and buyer B would be willing to buy a total of 5,000 shares. Thus, aggregate demand at a price of 50.00 is 65,000 shares. At this price, neither of seller X's or seller Y's priced orders would be executed. Thus, aggregate supply would equal the total number of unpriced order shares, 25,000. [0068] At a price 50.10, buyer B is willing to buy a total of 5,000 shares, buyer A is willing to buy a total of 50,000 shares (this number being the number of unpriced shares ordered by buyer A). For this price, again neither seller X nor seller Y are willing to buy any priced shares. Therefore, aggregate supply is 25,000 shares. [0069] At a price of 50.20, aggregate demand equals 50,000 shares (this being the number of shares represented by unpriced buys), and aggregate supply is 40,000 shares (this being the number of shares available for sale at a price of 50.20 plus the number of unpriced shares offered). [0070] At the price of 50.30, aggregate demand equals 50,000 and aggregate supply equals 60,000. [0071] Taking the smaller of aggregate demand and aggregate supply at each of the above prices, we will find the total number of shares which will transact at that particular price. Thus, at a price of 50.00, 25,000 shares would be transacted, at 50.10, 25,000 shares would be transacted, at 50.20, 40,000 shares, and at 50.30, 50,000 shares. Therefore, the maximum amount of shares will transact at a share maximizing price of 50.30 wherein 50,000 shares will be executed. [0072] Often, a discrete price cannot be identified. In these circumstances, the price discovery algorithm used in embodiments of the present invention will identify a range of prices 204 that will cause a maximum amount of shares to be executed. Along this range of prices, the amount of shares traded would be constant. In instances where a discrete price cannot be identified, the price discovery algorithm uses the relative amounts of bids (offers to buy) and offers (offers to sell) to determine which price along the range of volume maximizing prices will be discovered. [0073] The price discovery algorithm according to embodiments of the present invention in circumstances where no discrete price is identified first makes a determination 205 as to whether the bid shares are substantially equal to the offered shares. This can be done, for example, by mathematically computing an imbalance ratio (“R”) defined as [0000] R =  B - O  L Equation   1 [0000] wherein “B” is defined as the number of shares bid to buy at the highest price within the volume maximizing range, “O” is the number of shares offered to sell at the lowest price within the volume maximizing range, and L equals the lesser of O or B. This imbalance ratio is then compared to a predefined standard (“S”) for the given security. [0074] Next, the price discovery algorithm compares the imbalance ratio R to the standard S 206 . If the imbalance ratio is less than the appropriate standard 207 , the discovered price is identified as the mid-point price within the share volume maximizing range of prices 208 . This represents a determination that the net order imbalance is not large enough to significantly impact price. Example 3 [0075] Same facts as example 1, except that X and Y only wish to sell 5,000 shares apiece for ⅜. [0076] The standard “S” for the particular stock in question is 0.25 (representing a belief that a 25% excess of supply over demand, or vice versa, would constitute a large enough net order imbalance to significantly impact price). [0077] Using equation 1, B is 10,000, O is 10,000, and L is 10,000, thus R is calculated to equal 0.00 (i.e., no net order imbalance). Since R is less than S, the net order imbalance is deemed to not significantly impact price. [0078] Given that X and Y will sell 5,000 shares apiece (10,000 total) whether the price is ½ or ⅜ (there is no single volume maximizing price) and that R is less than S, the discovered price will be the mid-point of the volume maximizing range (⅜ to ½). Thus, the price is 7/16. [0079] If the imbalance ratio is greater than the appropriate standard 209 , the imbalance of supply and demand of the particular stock within the volume maximizing range is considered to have become large enough to impact price. Where the number of bids is found to significantly outnumber the number of offers 210 (B>0), the market price is considered demand driven 211 and results in a discovered price equal to the highest price within the share maximizing range. Conversely, where offers significantly outweigh the number of bids (O>B), the market price is supply driven 213 and results in a discovered price equal to the lowest price within the share maximizing range 214 . Example 4 [0080] The same facts as in example 3, except that a third buyer, Buyer C, submits a priced order to buy 10,000 shares at ½. [0081] Using equation 1, B is 20,000, O is 10,000, and L is 10,000, thus R is calculated to equal 0.50. Since R is greater than or equal to S (in this instance S=0.25), the net order imbalance is deemed to significantly impact price. [0082] This net order imbalance creates a demand driven price, thus the discovered price is set to the highest price within the volume maximizing range, namely ½. [0083] In alternative embodiments of the present invention, more than one standard may be used. In addition to the standard S which, if exceeded, denotes order imbalances which are large enough to warrant completely tipping the price to either the highest or lowest price within a range, a lower preliminary standard S′ can be used to measure when a predetermined partial tipping of price should be employed. Thus, if B>O, and S>R>S′, the price would not be demand driven, but only demand pressured. In situations where price is demand or supply pressured, the discovered price would be offset somewhere between the midpoint and the appropriate endpoint of the price maximizing range. Example 5 [0084] Buyer D enters a priced order offering to buy 75,000 shares of stock IOU for 50.35. [0085] Seller Z enters a priced order offering to buy 50,000 shares of stock IOU for 49.95. [0086] Stock IOU has a standard, S, set within the auction system equal to 0.60, and a preliminary standard, S′, set within the auction system equal to 0.40. [0087] For this example, at any price within the range of 49.95 through 50.35, 50,000 shares of IOU will be exchanged. Using equation 1, the imbalance ratio, R, is calculated to be 0.50, which is less than S, but larger than S′. Thus the price is considered to be demand pressured, but not demand driven. Thus, the determined price will be selected from a price somewhere between the demand driven price, 50.35, and the mid-point of the bid-offer spread, 50.15. A suitable price, for example, could be 50.25, the mid-point of the range of demand pressured price range. [0088] As will be readily apparent to those of ordinary skill in the art, the standard(s) with which to compare the imbalance ratio to can vary from security to security and upon prevailing market conditions. When embodiments of the present invention are performed electronically, the standard can be linked to market indicators (security Beta and volatility, for example) preferably provided continuously by an independent electronic wire service. Further, the value of the standard for a single security can be dependent upon whether there is a demand driven (B>>O) or supply driven (O>>B) imbalance. [0089] For those auctions where no price is discovered, such as in the case where there are no priced orders which intersect which define a share maximizing price, a default price, termed the reference price (“P R ”), that is derived from a combination of the orders currently in the order book and continuous market quotes will be computed and disseminated at the end of the auction cycle. This reference price in turn, as described above, will be used to execute cross orders and unpriced orders. Details of the reference price calculation will depend on the specific implementation of the system. [0090] In preferred embodiments of the invention, the reference price calculation algorithm will be performed by software running on one or more computers and will vary depending upon whether the particular auction cycle is being conducted as a closing, an opening, or as a normal periodic auction in conjunction with continuous trading on a continuous trading market. [0091] For a batch auction cycle occurring at the close of trading or during trading, the order acceptance period occurs while the continuous market is open. Thus, an accurate measure of an optimal price, assuming no volume maximizing price is identified by the price determination algorithm employed, may be identified as being the mid-point of the of the most recently published unqualified complete quotation (quotation having a valid bid, bid size, valid offer, and offer size) reported by the continuous market prior to the beginning of the price discovery period. [0092] For a batch auction occurring at the opening of the continuous trading market, the order acceptance period occurs while the continuous trading market is closed. Thus, quotes from trading in the continuous market cannot be used to set the reference price. Thus, in situations where there are only priced offers and no priced bids, and the highest bid is higher than the most recently published unqualified trade price (“MRPUTP”), as obtained from a consolidated tape system or other real time quote service, the reference price is set equal to the highest bid price. Where there are no priced offers, and the lowest offer is lower than the MRPUTP, the reference price is set equal to the lowest offer price. In all other scenarios with opening auction cycles, such as when there are no priced orders within the system, the reference price is defined as the MRPUTP. [0093] After a discovered price is identified by the price discovery algorithm, the price discovery period ends and the final part of the auction cycle, the order execution period, begins. During this final period, the volume maximizing amount of shares which are executed at the discovered price are fairly allocated among “qualifying” orders. Qualifying orders include all unpriced orders as well as priced orders that are at least as aggressive (bid orders having a price greater than or equal to the discovered price, and offer orders having a price less than the discovered price) as the discovered price. During the order execution period, each qualifying order will receive a pro-rata allocation of the available liquidity, i.e, the shares of the given security which will be traded during that particular auction cycle. Example 6 [0094] Given the facts according to example 3, the full 10,000 shares sold by X and Y at 7/16 is allocated to A because the discovered price is higher than the price entered by B. Thus, A is the only buyer willing to pay the discovered price. Example 7 [0095] Given the facts according to example 4, the 10,000 shares sold by X and Y at ½ is allocated pro-rata to each buyer willing to meet that discovered price. Buyers A and C are both willing to buy up to 10,000 shares apiece at a price of ½, thus the shares are allocated equally between them. Thus, A and C are each allocated 5,000 shares at ½. [0096] After the trades are allocated among qualifying orders, each trader is notified of the results of their order, including whether a trade did or did not occur, whether their order was a qualifying order, the price at which trades occurred (if applicable), and the quantity traded shares allocated to him (if applicable). Optionally, in embodiments of the present invention, other information can be provided to the trader post auction including the net order imbalance and total number of shares executed. When qualifying orders were electronically submitted, trader notification of auction results can be performed electronically as well. [0097] A batch auction system in preferred embodiments of the present invention is connected to one or more ECNs such that non-executed shares can be automatically sent to outside sources for execution. Thus, participants who had submitted priced orders having less aggressive prices than the discovered price, or having a net order imbalance, could attempt to have their desired trades executed outside the batch auction. [0098] In an alternative embodiment of the present invention as depicted by FIG. 5 , one or more designated intermediaries will be responsible for filling all eligible orders that would otherwise be unfilled, at the auction price. Thus, no unmatched orders would be generated. All unpriced orders as well as priced orders that are at least as aggressive as the discovered price will be filled in their entirety. In return for fulfilling this obligation, the intermediaries receive the benefit of viewing the entire limit order book for each security for which they are the designated intermediary during the auction process. [0099] In embodiments of the present invention which employ an intermediary, the designated market maker will have discretion to extend the auction. As with specialists on the NYSE and TSE, the intermediary will be subject to pre-defined market or exchange guidelines and will be subject to sanctions in the event that an inappropriate extension is made. [0100] As will be apparent to one of ordinary skill in the art, the present system can be modified in a variety of manners to provide additional functional features. By way of example, the permissible order types may be modified, or new order types introduced in alternative embodiments of the present invention. Such a new order type could be in the form of a “contingent order” which represents a desire by the trader to “only buy security A if I can sell security B and the price ratio of A:B is less than X.” Also by way of example, order types may be modified to allow the specification of portfolio dollar constraints. Such constraints would permit a series of orders for different securities to be linked as a portfolio, and only permit orders in that portfolio to be executed to the extent that maximum levels (in value terms) of net buying and selling are not exceeded. [0101] The invention being thus described, it will be apparent to those skilled in the art that the same may be varied in many ways without departing from the spirit and scope of the invention. Any and all such modifications are intended to be included within the scope of the following claims.

A method and system for performing a batch auction whereby a series of orders, according to a variety of predetermined order types, are generated by qualified market participants and communicated to an auction system. The auction system takes into account each order and its impact upon relative supply and demand to determine by a preset algorithm a price and share transaction quantity. Trades are executed at the price, and a portion of the transaction quantity is allocated to each investor on a fair basis dependent upon their initial orders. In embodiments of the present invention, the auction system uses a computer system or network designed to automatically perform one or more steps of the above method. Such a system is preferably connected to one or more ECNs such that non-executed shares can be automatically sent to outside sources for execution. In alternative embodiments, the invention includes the use of a one or more intermediaries or market makers to cover certain unexecuted trades at the determined price. The present invention is preferably used to conduct batch auctions at the opening and closing of securities trading markets.

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a division of U.S. patent application Ser. No. 12/580,689, filed Oct. 16, 2009, which is a continuation-in-part of U.S. patent application Ser. No. 12/421,762, filed Apr. 10, 2009, which claims the benefit of U.S. Provisional Application No. 61/150,554, filed Feb. 6, 2009, the entireties of which are incorporated by reference herein. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The invention generally relates to systems capable of transmitting electrical power without wires. [0004] 2. Background [0005] As used herein, the term wireless power transfer refers to a process by which electrical energy is transmitted from a power source to an electrical load without interconnecting wires. Wireless power transfer is useful for applications in which instantaneous or continuous energy transfer is needed, but for which providing a wired connection is inconvenient, hazardous, or impossible. [0006] It has been observed that while electromagnetic radiation (such as radio waves) is excellent for transmitting information wirelessly, it is generally not suitable for transferring power wirelessly. For example, if power were transferred using omnidirectional electromagnetic waves, a vast majority of the power would end up being wasted in free space. Directed electromagnetic radiation such as lasers might be used to transfer power between a power source and a device, but this is not very practical and could even be dangerous. Such an approach would also require an uninterrupted line of sight between the power source and the device, as well as a sophisticated tracking mechanism when the device is mobile. [0007] For the foregoing reasons, conventional systems that transfer power wirelessly are typically based on the concept of electromagnetic induction rather than electromagnetic radiation. These systems include systems based on inductive coupling and systems based on so-called “resonant inductive coupling.” [0008] Inductive coupling refers to the transfer of energy from one circuit component to another through a shared electromagnetic field. In inductive coupling, a current running in an emitting coil induces another current in a receiving coil. The two coils are in close proximity, but do not touch. [0009] Inductive coupling has been used in a variety of systems, including but not limited to systems that wirelessly charge a battery in a portable electronic device. In such systems, the portable electronic device is placed in close proximity to a charging station. A first induction coil in the charging station is used to create an alternating electromagnetic field, and a second induction coil in the portable electronic device derives power from the electromagnetic field and converts it back into electrical current to charge the battery. Thus, in such systems, there is no need for direct electrical contact between the battery and the charging station. [0010] Some examples of various different types of charging systems based on the principle of inductive coupling are described in U.S. Pat. No. 3,938,018 to Dahl, entitled “Induction Charging System,” U.S. Pat. No. 4,873,677 to Sakamoto et al., entitled “Charging Apparatus for an Electronic Device,” U.S. Pat. No. 5,952,814 to Van Lerberghe, entitled “Induction Charging Apparatus and an Electronic Device,” U.S. Pat. No. 5,959,433 to Rohde, entitled “Universal Inductive Battery Charger System,” and U.S. Pat. No. 7,042,196 to Ka-Lai et al., entitled “Contact-less Power Transfer,” each of which is incorporated by reference as if fully set forth herein. Examples of some conventional devices that include batteries that may be recharged via inductive coupling include the Braun Oral B Plak Control Power Toothbrush, the Panasonic Digital Cordless Phone Solution KX-PH15AL and the Panasonic multi-head men's shavers ES70/40 series. [0011] Another example of a technology that supports the use of inductive coupling to wirelessly transfer power is called Near Field Communication (NFC). NFC is a short-range high frequency wireless communication technology that enables the exchange of data between devices over approximately a decimeter distance. NFC is an extension of the ISO/IEC 14443 proximity-card standard that combines the interface of a smartcard and a reader into a single device. An NFC device can communicate with both existing ISO/IEC 14443 smartcards and readers, as well as with other NFC devices, and is thereby compatible with existing contactless infrastructure already in use for public transportation and payment. The air interface for NFC is described in ISO/IEC 18092/ECMA-340: Near Field Communication Interface and Protocol-1 (NFCIP-1) and ISO/IEC 21481/ECMA-352: Near Field Communication Interface and Protocol-2 (NFCIP-2), which are incorporated by reference herein. [0012] NFC devices communicate via magnetic field induction, wherein two loop antennas are located within each other's near field, effectively forming an air-core transformer. In a passive communication mode, an initiator device provides a carrier field and a target device answers by modulating the existing field. In this mode, the target device may draw its operating power from the initiator-provided electromagnetic field. [0013] “Resonant inductive coupling” refers to a more recently-publicized type of inductive coupling that utilizes magnetically-coupled resonators for wirelessly transferring power. In a system that uses resonant inductive coupling, a first coil attached to a sending unit generates a non-radiative magnetic field oscillating at megahertz (MHz) frequencies. The non-radiative field mediates a power exchange with a second coil attached to a receiving unit, which is specially designed to resonate with the field. The resonant nature of the process facilitates a strong interaction between the sending unit and the receiving unit, while the interaction with the rest of the environment is weak. Power that is not picked up by the receiving unit remains bound to the vicinity of the sending unit, instead of being radiated into the environment and lost. [0014] Resonant inductive coupling is said to enable relatively efficient wireless power transfer over distances that are a few times the size of the device to be powered, therefore exceeding the performance of systems based on non-resonant inductive coupling. An example of a wireless power transfer system based on resonant inductive coupling is described in U.S. Patent Application Publication No. 2007/0222542 to Joannopoulos et al., entitled “Wireless Non-radiative Energy Transfer,” which is incorporated by reference herein. [0015] Given the explosive growth in the use of portable electronic devices such as laptop computers, cellular telephones, and portable media devices, it is anticipated that there will be a strong demand for systems that facilitate the wireless recharging of power sources based on various types of near field inductive coupling such as those described above. Indeed, it may be deemed desirable to make such systems available in public spaces such as airports or in commercial establishments such as restaurants or hotels to allow users to recharge their portable electronic devices while away from home. [0016] Such wireless transfer of power in public or commercial environments may be made available to users for a fee. However, in order to achieve this, the wireless power transfer system must provide a secure and efficient way of obtaining requisite payment information from a user prior to performing the wireless power transfer. Still further, to accommodate wireless recharging of a variety of device types and states, the desired system should be able to receive parameters and/or state information associated with a portable electronic device to be recharged and to control the wireless power transfer in accordance with such parameters and/or state information. [0017] Unfortunately, none of the foregoing systems based on inductive coupling or resonant inductive coupling provide such features. For example, although NFC devices may use magnetic field induction to wirelessly transfer power as well as payment information and other types of data, it does not appear that such NFC devices are designed to use the wirelessly transferred power to recharge a power source associated with a portable electronic device. Furthermore, it does not appear that such devices control the wireless power transfer based on parameters and/or state information received from the portable electronic device having a power source to be recharged. Moreover, conventional techniques for transferring power wirelessly do not allow for feedback to increase efficiency of the wireless power transfer. BRIEF SUMMARY OF THE INVENTION [0018] A system and/or method for increasing efficiency of wireless power transfer, substantially as shown in and/or described in connection with at least one of the figures, as set forth more completely in the claims. BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES [0019] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate embodiments of the present invention and, together with the description, further serve to explain the principles involved and to enable a person skilled in the relevant art(s) to make and use the disclosed technologies. [0020] FIG. 1 is a block diagram of an example wireless power transfer system in accordance with an embodiment described herein. [0021] FIG. 2 depicts a flowchart of a method for wirelessly transferring power from a charging station to a portable electronic device in accordance with an embodiment described herein. [0022] FIG. 3 depicts a flowchart of a method for wirelessly receiving power from a charging station by a portable electronic device in accordance with an embodiment described herein. [0023] FIG. 4 depicts a flowchart of an additional method for wirelessly transferring power from a charging station to a portable electronic device in accordance with an embodiment described herein. [0024] FIG. 5 depicts a flowchart of an additional method for wirelessly receiving power from a charging station by a portable electronic device in accordance with an embodiment described herein. [0025] FIG. 6 is a block diagram of a wireless power transfer system in accordance with an embodiment described herein in which a wireless power link is established using a receiver and transmitter and a wireless communication link is established using a separate pair of transceivers. [0026] FIG. 7 is a block diagram of a wireless power transfer system in accordance with an alternate embodiment described herein in which a wireless communication link between a portable electronic device and a charging station is unidirectional. [0027] FIG. 8 is a block diagram of a wireless power transfer system in accordance with an alternate embodiment described herein in which a charging station includes a plurality of different communication link transceivers to facilitate the establishment of wireless communication links with a plurality of different types of portable electronic devices. [0028] FIG. 9 depicts a flowchart of a method for increasing efficiency of wireless power transfer in accordance with an embodiment described herein. [0029] FIGS. 10 , 12 , 14 , and 16 are block diagrams of example implementations of a charging station in accordance with embodiments described herein. [0030] FIGS. 11A-11D depict respective portions of a flowchart of a method for increasing efficiency of wireless power transfer in accordance with an embodiment described herein. [0031] FIGS. 13 , 15 , and 17 - 21 depict flowcharts of methods for increasing efficiency of wireless power transfer in accordance with embodiments described herein. [0032] FIG. 22 is a block diagram of an example implementation of a portable electronic device in accordance with an embodiment described herein. [0033] The features and advantages of the disclosed technologies will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the corresponding reference number. DETAILED DESCRIPTION OF THE INVENTION I. Introduction [0034] The following detailed description refers to the accompanying drawings that illustrate example embodiments of the present invention. However, the scope of the present invention is not limited to these embodiments, but is instead defined by the appended claims. Thus, embodiments beyond those shown in the accompanying drawings, such as modified versions of the illustrated embodiments, may nevertheless be encompassed by the present invention. [0035] References in the specification to “one embodiment,” “an embodiment,” “an example embodiment,” or the like, indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to implement such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. [0036] Various approaches are described herein for, among other things, increasing efficiency of wireless power transfer. The efficiency of a wireless power transfer is defined as the magnitude of power that is consumed by a portable electronic device with respect to the wireless power transfer divided by the magnitude of power that is provided to the portable electronic device with respect to the wireless power transfer. The efficiency of the wireless power transfer therefore indicates the proportion of the power that is wirelessly transferred to the portable electronic device that is consumed by the portable electronic device. [0037] For example, a charging station may begin to wirelessly transfer power to a portable electronic device via a wireless power link. The portable electronic device may be configured to send an indicator to the charging station via a wireless communication link once the charging station begins to wirelessly transfer the power to the portable electronic device. The indicator specifies information regarding the portable electronic device, which may include but is not limited to a resonant frequency of the portable electronic device, a magnitude of power requested by the portable electronic device, a magnitude of power consumed by the portable electronic power with respect to the wireless power transfer, a maximum safe power that the portable electronic device is capable of consuming without substantial risk of damaging the portable electronic device, a position of the portable electronic device, etc. The charging station may be configured to increase the efficiency of the wireless transfer of the power based on the indicator. [0038] A method is described for increasing efficiency of wireless power transfer. In accordance with this method, a wireless power transfer is initiated from a charging station to a portable electronic device via a wireless power link. Parameter(s) regarding the portable electronic device are received at the charging station via a wireless communication link in response to initiation of the wireless power transfer. Efficiency of the wireless power transfer is increased based on the parameter(s). [0039] Another method is described for increasing efficiency of wireless power transfer. In accordance with this method, power is wirelessly transferred to a portable electronic device via a wireless power link. Parameter(s) received via a wireless communication link regarding the portable electronic device with respect to the wireless transfer of the power are analyzed. Efficiency with respect to the wireless transfer of the power is increased based on analysis of the parameter(s). [0040] Yet another method is described for increasing efficiency of wireless power transfer. In accordance with this method, power is wirelessly received for a first period of time at a portable electronic device from a charging station via a wireless power link having a first transmission efficiency. Parameter(s) regarding the portable electronic device with respect to receipt of the power during the first period of time are provided to the charging station via a wireless communication link. Power is wirelessly received for a second period of time at the portable electronic device from the charging station via the wireless power link having a second transmission efficiency in response to providing the parameter(s) to the charging station. The second transmission efficiency is greater than the first transmission efficiency. [0041] A system is described that includes a wireless power transfer module, a parameter receipt module, and an efficiency improvement module. The wireless power transfer module is configured to initiate a wireless power transfer to a portable electronic device via a wireless power link. A parameter receipt module is configured to receive parameter(s) regarding the portable electronic device via a wireless communication link in response to initiation of the wireless power transfer. An efficiency improvement module is configured to increase efficiency of the wireless power transfer based on the parameter(s). [0042] Another system is described that includes a wireless power transfer module, a parameter analysis module, and an efficiency improvement module. The wireless power transfer module is configured to wirelessly transfer power to a portable electronic device via a wireless power link. The parameter analysis module is configured to analyze parameter(s) received via a wireless communication link regarding the portable electronic device with respect to the wireless transfer of the power. The efficiency improvement module is configured to increase efficiency with respect to the wireless transfer of the power based on analysis of the parameter(s). [0043] Yet another system is described that includes a wireless power receipt module and a parameter module. The wireless power receipt module is configured to wirelessly receive power for a first period of time from a charging station via a wireless power link having a first transmission efficiency. The parameter module is configured to provide parameter(s) regarding the system with respect to receipt of the power during the first period of time to the charging station via a wireless communication link. The wireless power receipt module is further configured to wirelessly receive power for a second period of time from the charging station via the wireless power link having a second transmission efficiency in response to providing the parameter(s) to the charging station. The second transmission efficiency is greater than the first transmission efficiency. II. Example Wireless Power Transfer System in Accordance with an Embodiment [0044] FIG. 1 is a block diagram of an example wireless power transfer system 100 in accordance with an embodiment described herein. System 100 includes a charging station 102 and a portable electronic device 104 . As will be described in more detail herein, charging station 102 is configured to wirelessly transfer power to portable electronic device 104 responsive to receipt of payment information therefrom. Charging station 102 is also configured to manage the wireless transfer of power to portable electronic device 104 based on certain parameters and/or state information received from portable electronic device 104 . [0045] As shown in FIG. 1 , charging station 102 includes a power source 122 connected to a wireless power/communication link transceiver 124 . Wireless power/communication link transceiver 124 is configured to wirelessly transfer power supplied by power source 122 to a wireless power/communication link transceiver 146 associated with portable electronic device 104 via an inductive link 106 . As will be appreciated by persons skilled in the relevant art(s), such wireless power transfer may be carried out over inductive link 106 in accordance with the well-known principles of inductive coupling or resonant inductive coupling as discussed in the Background Section above. As will be further appreciated by persons skilled in the relevant art(s), the manner in which wireless power/communication link transceiver 124 and wireless power/communication link transceiver 146 are implemented will depend on the type of inductive coupling used. A variety of transceiver designs based on inductive coupling and resonant inductive coupling are available in the art and thus need not be described herein. [0046] Charging station 102 also includes a power link manager 126 connected between power source 122 and wireless power/communication link transceiver 124 . Power link manager 126 is configured to sense when wireless power/communication link transceiver 146 associated with portable electronic device 104 is inductively coupled to wireless power/communication link transceiver 124 and is thus capable of receiving power wirelessly therefrom. Power link manager 126 is further configured to transfer power wirelessly over inductive link 106 responsive to control signals from a communication link manager 128 . Power link manager 126 may be further configured to monitor the amount of power that is wirelessly transferred via inductive link 106 to portable electronic device 104 . [0047] Communication link manager 128 is connected both to power link manager 126 and to wireless power/communication link transceiver 124 . Communication link manager 128 is configured to establish and maintain a wireless communication link with portable electronic device 104 via wireless power/communication link transceiver 124 for the purpose of obtaining payment information and other information therefrom. Such other information may include, for example, device-specific parameters associated with portable electronic device 104 such as a maximum safe power that may be transferred to portable electronic device 104 . Such other information may also include, for example, state information associated with portable electronic device 104 such an amount of power currently consumed or needed by portable electronic device 104 . [0048] Communication link manager 128 is thus configured to use inductive link 106 for the wireless communication of data. Depending upon the implementation, communication link manager 128 may be configured to carry out the wireless communication of data in accordance with any standard or proprietary induction-based data communication protocol. For example, communication link manager 128 may be configured to carry out the wireless communication of data in accordance with an NFC protocol as described in the Background Section above, although this example is not intended to be limiting and other standard or proprietary induction-based data communication protocols may be used. [0049] Communication link manager 128 is further configured to transmit control signals to power link manager 126 to control whether and when power link manager 126 may transfer power wirelessly to portable electronic device 104 . Communication link manager 128 can thus ensure that power is transferred to portable electronic device 104 only after requisite payment information has been received from portable electronic device 104 . Communication link manager 128 can also control power link manager 126 to ensure that power is delivered to portable electronic device 104 in a manner that takes into account certain device-specific parameters such as a maximum safe power that may be transferred to portable electronic device 104 or state information such as an amount of power currently consumed or needed by portable electronic device 104 . [0050] Portable electronic device 104 within power transfer system 100 will now be described. As shown in FIG. 1 , portable electronic device 104 includes a battery recharging unit 144 connected to wireless power/communication link transceiver 146 . Wireless power/communication link transceiver 146 is configured to transfer wireless power received over inductive link 106 to battery recharging unit 144 , which is configured to use such power to recharge a battery 142 connected thereto. Battery recharging unit 144 is also connected to a load 154 associated within portable electronic device 104 , which can be powered by battery 142 in a well-known manner. [0051] Portable electronic device 104 further includes a power link monitor 148 connected between wireless power/communication link transceiver 146 and battery recharging unit 144 . Power link monitor 148 may be configured to monitor an amount of power that is wirelessly received via inductive link 106 and to provide this information to a communication link manager 150 . Power link monitor 148 may provide other state information to communication link manager 150 including, for example, a current state of battery 142 . [0052] Communication link manager 150 is connected both to power link monitor 148 and to wireless power/communication link transceiver 146 . Communication link manager 150 is configured to establish and maintain a wireless communication link with charging station 102 via wireless power/communication link transceiver 146 for the purpose of providing payment information and other information thereto. As noted above, such other information may include, for example, device-specific parameters associated with portable electronic device 104 , such as a maximum safe power that may be transferred to portable electronic device 104 , or state information associated with portable electronic device 104 such an amount of power currently consumed or needed by portable electronic device 104 . This state information may be based on or derived from state information provided by power link monitor 148 . [0053] Communication link manager 150 is thus configured to use inductive link 106 for the wireless communication of data. Depending upon the implementation, communication link manager 150 may be configured to carry out the wireless communication of data in accordance with any standard or proprietary induction-based data communication protocol. For example, communication link manager 150 may be configured to carry out the wireless communication of data in accordance with an NFC protocol as described in the Background Section above, although this example is not intended to be limiting and other standard or proprietary induction-based data communication protocols may be used. [0054] FIG. 2 depicts a flowchart 200 of a method for wirelessly transferring power from a charging station to a portable electronic device in accordance with an embodiment described herein. The method of flowchart 200 will now be described in reference to certain elements of example wireless transfer system 100 as described above in reference to FIG. 1 . However, the method is not limited to that implementation. [0055] As shown in FIG. 2 , the method of flowchart 200 begins at step 202 in which power link manager 126 of charging station 102 establishes a wireless power link with portable electronic device 104 . Power link manager 126 performs this function by allowing power to flow from power source 122 to wireless power/communication link transceiver 124 , which has the effect of creating inductive link 106 between wireless power/communication link transceiver 124 of charging station 102 and wireless power/communication link transceiver 146 of portable electronic device 104 . As discussed above, depending upon the implementation of wireless power/communication link transceiver 124 and wireless power/communication link transceiver 146 , inductive link 106 may be created for example based on the principles of inductive coupling or resonant inductive coupling. [0056] At step 204 , communication link manager 128 of charging station 102 establishes a wireless communication link with portable electronic device 104 . Communication link manager 128 performs this function by transmitting and/or receiving signals via wireless power/communication link transceiver 124 to/from wireless power/communication link transceiver 146 associated with portable electronic device 104 . The wireless communication link is thus established via inductive link 106 . As discussed above, the wireless communication link may be established in accordance with any standard or proprietary inductance-based data communication protocol. [0057] At step 206 , communication link manager 128 of charging station 102 receives payment information from portable electronic device 104 via the wireless communication link. As will be appreciated by persons skilled in the relevant art(s), the type of payment information that is received during step 206 may vary depending on the manner in which the wireless power transfer service is to be paid for by the user of portable electronic device 104 . [0058] For example, if the user will pay for the wireless power transfer through the subsequent billing of a credit card account, checking account, or some other account from which funds may be transferred, then the payment information may include a unique account identifier, such as an account number. Alternatively, if the charge to the user will be added to a list of additional charges due from the user (e.g., the charge is to be added to a hotel bill for the user), then the payment information may include a unique identifier of the user. [0059] Furthermore, if the user has already paid for the wireless power transfer, then the payment information may include an electronic token indicating that such payment has occurred. Alternatively, if the user has purchased prepaid credits towards the wireless power transfer, then the payment information may include an electronic funds amount that is currently available to the user/owner for obtaining the service. The electronic funds amount may be stored on portable electronic device 104 , or a card inserted or attached to portable electronic device 104 . [0060] The foregoing description of the types of payment information that may be received during step 206 are provided by way of example only and are not intended to limit the present invention. Persons skilled in the relevant art(s) will readily appreciate that other types of payment information may be received during step 206 other than or in addition to those types described above. [0061] After the payment information has been received by communication link manager 128 during step 206 , communication link manager 128 sends one or more control signals to power link manager 126 and, responsive to receiving the control signal(s), power link manager 126 allows power to be transferred to portable electronic device 104 over the wireless power link. This is generally shown at step 208 . [0062] In an embodiment, communication link manager 128 validates and/or processes the payment information prior to sending the control signal(s) to power link manager 126 . In another embodiment, communication link manager 128 transmits the payment information to an external entity for validation and/or processing prior to sending the control signal(s) to power link manager 126 . For example, communication link manager 128 may provide the payment information to a network interface within charging station 102 (not shown in FIG. 1 ) for wired or wireless communication to a network entity, such as a server, for processing and/or validation. [0063] In a further implementation of the foregoing method, power link manager 126 monitors or meters the amount of power wirelessly transferred to portable electronic device 104 via the wireless power link. The monitored amount can then be used to charge the user of portable electronic device 104 based on the amount of power transferred. In one embodiment, the monitored amount is transmitted to an external entity so that the user of portable electronic device 104 may be charged based on the monitored amount. The external entity may be, for example, a remote network entity, such as a server, or may be portable electronic device 104 . [0064] In the foregoing method of flowchart 200 , the establishment of the wireless power link in step 202 may occur before, contemporaneously with, or after the establishment of the wireless communication link in step 204 depending upon the implementation. Furthermore, the establishment of the wireless power link may occur responsive to the establishment of the wireless communication link or vice versa. With respect to the establishment of the wireless communication link, either charging station 102 or portable electronic device 104 may act as the initiator depending upon the implementation. [0065] FIG. 3 depicts a flowchart 300 of a method for wirelessly receiving power from a charging station by a portable electronic device in accordance with an embodiment described herein. In contrast to the steps of flowchart 200 , which are performed by a charging station, the steps of flowchart 300 are performed by a portable electronic device that is configured to interact with a charging station. Thus, the method of flowchart 300 may be thought of as a counterpart method to the method of flowchart 200 . [0066] The method of flowchart 300 will now be described in reference to certain elements of example wireless transfer system 100 as described above in reference to FIG. 1 . However, the method is not limited to that implementation. [0067] As shown in FIG. 3 , the method of flowchart 300 begins at step 302 in which a wireless power link is established between wireless power/communication link transceiver 146 of portable electronic device 104 and wireless power/communication link transceiver 124 of charging station 102 . The manner in which such a wireless power link is established was discussed above in reference to step 202 of flowchart 200 . [0068] At step 304 , communication link manager 150 of portable electronic device 104 establishes a wireless communication link with charging station 102 . Communication link manager 150 performs this function by transmitting and/or receiving signals via wireless power/communication link transceiver 146 to/from wireless power/communication link transceiver 124 associated with charging station 102 . The wireless communication link is thus established via inductive link 106 . As discussed above, the wireless communication link may be established in accordance with any standard or proprietary inductance-based data communication protocol. [0069] At step 306 , communication link manager 150 of portable electronic device 104 transmits payment information to charging station 102 via the wireless communication link. As will be appreciated by persons skilled in the relevant art(s), the type of payment information that is transmitted during step 306 may vary depending on the manner in which the wireless power transfer service is to be paid for by the user of portable electronic device 104 . Examples of various types of payment information were described above in reference to step 206 of flowchart 200 . [0070] Responsive to the receipt of the payment information by charging station 102 , charging station 102 transfers power to portable electronic device 104 over the wireless power link. The transferred power is received by wireless power/communication link transceiver 146 and applied to battery recharging unit 144 . This is generally shown at step 308 . [0071] In the foregoing method of flowchart 300 , the establishment of the wireless power link in step 302 may occur before, contemporaneously with, or after the establishment of the wireless communication link in step 304 depending upon the implementation. Furthermore, the establishment of the wireless power link may occur responsive to the establishment of the wireless communication link or vice versa. With respect to the establishment of the wireless communication link, either charging station 102 or portable electronic device 104 may act as the initiator depending upon the implementation. [0072] FIG. 4 depicts a flowchart 400 of an additional method for wirelessly transferring power from a charging station to a portable electronic device in accordance with an embodiment described herein. The method of flowchart 400 will now be described in reference to certain elements of example wireless transfer system 100 as described above in reference to FIG. 1 . However, the method is not limited to that implementation. [0073] As shown in FIG. 4 , the method of flowchart 400 begins at step 402 in which power link manager 126 of charging station 102 establishes a wireless power link with portable electronic device 104 . Power link manager 126 performs this function by allowing power to flow from power source 122 to wireless power/communication link transceiver 124 , which has the effect of creating inductive link 106 between wireless power/communication link transceiver 124 of charging station 102 and wireless power/communication link transceiver 146 of portable electronic device 104 . As discussed above, depending upon the implementation of wireless power/communication link transceiver 124 and wireless power/communication link transceiver 146 , inductive link 106 may be created based on the principles of inductive coupling or resonant inductive coupling for example. [0074] At step 404 , communication link manager 128 of charging station 102 establishes a wireless communication link with portable electronic device 104 . Communication link manager 128 performs this function by transmitting and/or receiving signals via wireless power/communication link transceiver 124 to/from wireless power/communication link transceiver 146 associated with portable electronic device 104 . The wireless communication link is thus established via inductive link 106 . As discussed above, the wireless communication link may be established in accordance with any standard or proprietary inductance-based data communication protocol. [0075] At step 406 , communication link manager 128 of charging station 102 receives parameters and/or state information from portable electronic device 104 via the wireless communication link. The parameters may include, for example, a maximum safe power that may be transmitted to portable electronic device 104 . The state information may include, for example, an amount of power currently consumed or needed by portable electronic device 104 . [0076] After receiving the parameters and/or state information, communication link manager 128 sends one or more control signals to power link manager 126 and, responsive to receiving the control signal(s), power link manager 128 transfers power to portable electronic device 104 over the wireless power link in a manner that takes into account the received parameters and/or state information. This is generally shown at step 408 . [0077] In one embodiment, controlling the power transfer in accordance with received parameters includes controlling the wireless power link to ensure that the amount of power transferred over the link does not exceed a maximum safe power that may be transmitted to portable electronic device 104 . In another embodiment, controlling the power transfer in accordance with received state information includes controlling the wireless power link to ensure that the amount of power that is transferred over the link is sufficient to recharge portable electronic device 104 or does not exceed an amount of power that is sufficient to recharge portable electronic device 104 . [0078] In the foregoing method of flowchart 400 , the establishment of the wireless power link in step 402 may occur before, contemporaneously with, or after the establishment of the wireless communication link in step 404 depending upon the implementation. Furthermore, the establishment of the wireless power link may occur responsive to the establishment of the wireless communication link or vice versa. With respect to the establishment of the wireless communication link, either charging station 102 or portable electronic device 104 may act as the initiator depending upon the implementation. [0079] FIG. 5 depicts a flowchart 500 of a method for wirelessly receiving power from a charging station by a portable electronic device in accordance with an embodiment described herein. In contrast to the steps of flowchart 400 , which are performed by a charging station, the steps of flowchart 500 are performed by a portable electronic device that is configured to interact with a charging station. Thus, the method of flowchart 500 may be thought of as a counterpart method to the method of flowchart 400 . [0080] The method of flowchart 500 will now be described in reference to certain elements of example wireless transfer system 100 as described above in reference to FIG. 1 . However, the method is not limited to that implementation. [0081] As shown in FIG. 5 , the method of flowchart 500 begins at step 502 in which a wireless power link is established between wireless power/communication link transceiver 146 of portable electronic device 104 and wireless power/communication link transceiver 124 of charging station 102 . The manner in which such a wireless power link is established was discussed above in reference to step 402 of flowchart 400 . [0082] At step 504 , communication link manager 150 of portable electronic device 104 establishes a wireless communication link with charging station 102 . Communication link manager 150 performs this function by transmitting and/or receiving signals via wireless power/communication link transceiver 146 to/from wireless power/communication link transceiver 124 associated with charging station 102 . The wireless communication link is thus established via inductive link 106 . As discussed above, the wireless communication link may be established in accordance with any standard or proprietary inductance-based data communication protocol. [0083] At step 506 , communication link manager 150 of portable electronic device 104 transmits parameters and/or state information to charging station 102 via the wireless communication link. As noted above, the parameters may include, for example, a maximum safe power that may be transmitted to portable electronic device 104 and the state information may include, for example, an amount of power currently consumed or needed by portable electronic device 104 . [0084] In an embodiment, communication link manager 150 generates or derives the state information from information collected by power link monitor 148 . For example, power link monitor 148 may monitor the wireless power link to determine an amount of power transferred over the link. This amount of power may then be reported as state information to charging station 102 over the wireless communication link. Additionally, power link monitor 148 may provide other state information to communication link manager 150 including, for example, a current state of battery 142 . [0085] Responsive to the receipt of the parameters and/or state information by charging station 102 , charging station 102 transfers power to portable electronic device 104 over the wireless power link, wherein the manner in which power is transferred is controlled in accordance with the parameters and/or state information. The transferred power is received by wireless power/communication link transceiver 146 and applied to battery recharging unit 144 . This is generally shown at step 508 . [0086] In the foregoing method of flowchart 500 , the establishment of the wireless power link in step 502 may occur before, contemporaneously with, or after the establishment of the wireless communication link in step 504 depending upon the implementation. Furthermore, the establishment of the wireless power link may occur responsive to the establishment of the wireless communication link or vice versa. With respect to the establishment of the wireless communication link, either charging station 102 or portable electronic device 104 may act as the initiator depending upon the implementation. III. Alternative Wireless Power Transfer System Implementations [0087] Alternative implementations of wireless power transfer system 100 will now be described. Each of the alternative implementations is also capable of wirelessly transferring/receiving power in accordance with the methods of flowcharts 200 , 300 , 400 and 500 as described above in reference to FIG. 2 , FIG. 3 , FIG. 4 and FIG. 5 , respectively. [0088] For example, FIG. 6 is a block diagram of a wireless power transfer system 600 that includes similar elements to those described in reference to FIG. 1 except that the wireless power link between the charging station and the portable electronic device is implemented using a wireless power transmitter and receiver while the wireless communication link between the charging station and the portable electronic device is implemented using a separate pair of communication link transceivers. [0089] As shown in FIG. 6 , wireless power transfer system 600 includes a charging station 602 and a portable electronic device 604 . Charging station 602 includes a power source 622 , a wireless power transmitter 624 , a power link manager 626 , a communication link manager 628 , and a communication link transceiver 630 . Portable electronic device 604 includes a battery 642 , a battery recharging unit 644 , a wireless power receiver 646 , a power link monitor 648 , a communication link manager 650 , a communication link transceiver 652 , and a load 654 . With the exception of certain elements discussed below, the elements of charging station 602 are configured to function in a similar manner to like-named elements of charging station 102 of FIG. 1 . Likewise, with the exception of certain elements discussed below, the elements of portable electronic device 604 are configured to function in a similar manner to like-named elements of portable electronic device 104 of FIG. 1 . [0090] Wireless power transmitter 624 is configured to operate under the control of power link manager 626 to wirelessly transfer power supplied by power source 622 to wireless power receiver 646 associated with portable electronic device 604 via an inductive link 606 . The wireless power transfer may be carried out over inductive link 606 in accordance with the well-known principles of inductive coupling or resonant inductive coupling as discussed in the Background Section above. The manner in which wireless power transmitter 624 and wireless power receiver 646 are implemented will depend on the type of inductive coupling used. A variety of transmitter and receiver designs based on inductive coupling and resonant inductive coupling are available in the art and thus need not be described herein. [0091] In the embodiment shown in FIG. 6 , communication link transceivers 630 and 652 are used to establish and maintain a wireless communication link 608 between charging station 602 and portable electronic device 604 that is separate from inductive link 606 . Wireless communication link 608 is established for the purpose of transferring payment information and/or device-specific parameters or state information from portable electronic device 604 to charging station 602 . Charging station 602 may then use such information in a like manner to that described above with respect to charging station 102 of FIG. 1 . [0092] As will be appreciated by persons skilled in the relevant art(s), the manner in which communication link transceivers 630 and 652 are implemented will depend on the type of wireless communication link to be established therebetween. In accordance with one embodiment, wireless communication link 608 may be established using NFC technology as described above in the Background Section. Alternatively, wireless communication link 608 may be established in accordance with certain RF-based short-range communication technologies such as Bluetooth™, as described in the various standards developed and licensed by the Bluetooth™ Special Interest Group, or technologies such as ZigBee® that are based on the IEEE 802.15.4 standard for wireless personal area networks (specifications describing ZigBee are publically available from the ZigBee® Alliance). Still further, wireless communication link 608 may be established in accordance with other RF-based communication technologies such as any of the well-known IEEE 802.11 protocols. However, these examples are not intended to be limiting, and wireless communication link 608 between charging station 602 and portable electronic device 604 may be established using a variety of other standard or propriety communication protocols. [0093] FIG. 7 is a block diagram of a wireless power transfer system 700 that includes similar elements to those described in reference to FIG. 6 except that the wireless communication link between the portable electronic device and the charging station is unidirectional rather than bidirectional. [0094] As shown in FIG. 7 , wireless power transfer system 700 includes a charging station 702 and a portable electronic device 704 . Charging station 702 includes a power source 722 , a wireless power transmitter 724 , a power link manager 726 , a communication link manager 728 , and a communication link receiver 730 . Portable electronic device 704 includes a battery 742 , a battery recharging unit 744 , a wireless power receiver 746 , a power link monitor 748 , a communication link manager 750 , a communication link transmitter 752 , and a load 754 . With the exception of certain elements discussed below, the elements of charging station 702 are configured to function in a similar manner to like-named elements of charging station 602 of FIG. 6 . Likewise, with the exception of certain elements discussed below, the elements of portable electronic device 704 are configured to function in a similar manner to like-named elements of portable electronic device 604 of FIG. 6 . [0095] Communication link manager 750 within portable electronic device 704 is configured to establish a unidirectional wireless communication link 708 with charging station 702 by transmitting signals via communication link transmitter 752 to communication link receiver 730 . This unidirectional wireless communication link may then be used to transmit payment information and/or device-specific parameters or state information from portable electronic device 704 to charging station 702 . Charging station 702 may then use such information in a like manner to that described above with respect to charging station 102 of FIG. 1 . [0096] FIG. 8 is a block diagram of a wireless power transfer system 800 that includes similar elements to those described in reference to FIG. 6 except that the charging station includes a plurality of different communication link transceivers to facilitate the establishment of wireless communication links with a plurality of different types of portable electronic devices. [0097] As shown in FIG. 8 , wireless power transfer system 800 includes a charging station 802 and a portable electronic device 804 . Charging station 802 includes a power source 822 , a wireless power transmitter 824 , a power link manager 826 , a communication link manager 828 , and a plurality of communication link transceivers 830 A- 830 N. Portable electronic device 804 includes a battery 842 , a battery recharging unit 844 , a wireless power receiver 846 , a power link monitor 848 , a communication link manager 850 , a communication link transceiver 852 , and a load 854 . With the exception of certain elements discussed below, the elements of charging station 802 are configured to function in a similar manner to like-named elements of charging station 602 of FIG. 6 . Likewise, with the exception of certain elements discussed below, the elements of portable electronic device 804 are configured to function in a similar manner to like-named elements of portable electronic device 604 of FIG. 6 . [0098] Each of the communication link transceivers 830 A- 830 N is configured for wireless communication in accordance with a different wireless protocol. For example, first communication link transceiver 830 A may be configured for communication in accordance with NFC, second communication link transceiver 830 B may be configured for communication in accordance with Bluetooth™, and Nth communication link transceiver 830 N may be configured for communication in accordance with one of the IEEE 802.11 standards. This advantageously enables charging station 802 to receive payment information and device-specific parameters and/or state information from a plurality of different device types to facilitate the wireless transfer of power to such devices. IV. Example Embodiments for Increasing Efficiency of Wireless Power Transfer [0099] Some example embodiments are capable of increasing efficiency of wireless power transfer. The efficiency of a wireless power transfer is defined as the magnitude of power that is consumed by a portable electronic device with respect to the wireless power transfer divided by the magnitude of power that is provided to the portable electronic device with respect to the wireless power transfer. The efficiency of the wireless power transfer therefore indicates the proportion of the power that is wirelessly transferred to the portable electronic device that is consumed by the portable electronic device. [0100] In accordance with some example embodiments, a charging station (e.g., charging station 102 , 602 , 702 , or 802 ) begins to wirelessly transfer power to a portable electronic device (e.g., portable electronic device 104 , 604 , 704 , or 804 ) via a wireless power link (e.g., link 106 , 606 , 706 , or 806 ). The portable electronic device sends an indicator to the charging station via a wireless communication link (e.g., link 106 , 608 , 708 , or 808 ) once the charging station begins to wirelessly transfer the power to the portable electronic device. The indicator specifies information regarding the portable electronic device, which may include but is not limited to a resonant frequency of the portable electronic device, a magnitude of power requested by the portable electronic device, a magnitude of power consumed by the portable electronic power with respect to the wireless power transfer, a maximum safe power that the portable electronic device is capable of consuming without substantial risk of damaging the portable electronic device, a position of the portable electronic device, etc. The charging station increases the efficiency of the wireless transfer of the power based on the indicator. [0101] FIG. 9 depicts a flowchart 900 of a method for increasing efficiency of wireless power transfer in accordance with an embodiment described herein. Flowchart 900 may be performed by charging station 102 , 602 , 702 , or 802 of respective wireless power transfer system 100 , 600 , 700 , or 800 shown in respective FIG. 1 , 6 , 7 , or 8 , for example. For illustrative purposes, flowchart 900 is described with respect to a charging system 1000 shown in FIG. 10 , which is an example of a charging station 102 , 602 , 702 , or 802 , according to an embodiment. [0102] As shown in FIG. 10 , charging station 1000 includes a wireless power transfer module 1002 , a parameter receipt module 1004 , and an efficiency improvement module 1006 . Further structural and operational embodiments will be apparent to persons skilled in the relevant art(s) based on the discussion regarding flowchart 900 . Flowchart 900 is described as follows. [0103] As shown in FIG. 9 , the method of flowchart 900 begins at step 902 . In step 902 , a wireless power transfer is initiated from a charging station to a portable electronic device via a wireless power link. The wireless power transfer may be performed in accordance with an inductive coupling technique, a resonant inductive coupling technique, or any other suitable technique. In an example implementation, wireless power transfer module 1002 initiates the wireless power transfer via the wireless power link. [0104] At step 904 , at least one parameter regarding the portable electronic device is received at the charging station via a wireless communication link. For instance, the at least one parameter may be received via the wireless communication link in accordance with a Near Field Communication (NFC) protocol, a Bluetooth™ protocol, a ZigBee® protocol, an IEEE 802.11 protocol, or any other suitable protocol. The wireless power link and the wireless communication link may be implemented as separate links or as a common link. The wireless power link and the wireless communication link may be inductive links, though the scope of the example embodiments is not limited in this respect. In an example implementation, parameter receipt module 1004 receives the at least one parameter. [0105] At step 906 , efficiency of the wireless power transfer is increased based on the at least one first parameter. In an example implementation, efficiency improvement module 1006 increases the efficiency of the wireless power transfer. Some example techniques for increasing the efficiency of wireless power transfer are described below with reference to FIGS. 11A-11D , 12 , 15 , and 16 , for example. [0106] FIGS. 11A-11D depict respective portions of a flowchart 1100 of a method for increasing efficiency of wireless power transfer in accordance with an embodiment described herein. Flowchart 1100 may be performed by charging station 102 , 602 , 702 , or 802 of respective wireless power transfer system 100 , 600 , 700 , or 800 shown in respective FIG. 1 , 6 , 7 , or 8 , for example. For illustrative purposes, flowchart 1100 is described with respect to a charging system 1200 shown in FIG. 12 , which is an example of a charging station 102 , 602 , 702 , or 802 , according to an embodiment. [0107] As shown in FIG. 12 , charging station 1200 includes a wireless power transfer module 1202 , a parameter receipt module 1204 , a parameter determination module 1206 , a frequency comparison module 1208 , an efficiency improvement module 1210 , a power comparison module 1212 , and an orientation determination module 1214 . Further structural and operational embodiments will be apparent to persons skilled in the relevant art(s) based on the discussion regarding flowchart 1100 . Flowchart 1100 is described as follows. [0108] As shown in FIG. 11 , the method of flowchart 1100 begins at step 1102 . In step 1102 , a wireless power transfer is initiated from a charging station to a portable electronic device via a wireless power link. In an example implementation, wireless power transfer module 1202 initiates the wireless power transfer via the wireless power link. [0109] At step 1104 , a determination is made whether a frequency parameter that specifies a resonant frequency of the portable electronic device is received via a wireless communication link. In an example implementation, parameter determination module 1206 determines whether a frequency parameter that specifies the resonant frequency of the portable electronic device is received. For instance, parameter receipt module 1204 may receive the frequency parameter. If the frequency parameter that specifies the resonant frequency of the portable electronic device is received via the wireless communication link, flow continues to step 1108 . Otherwise, flow continues to step 1110 . [0110] According to one example embodiment, the wireless power link and the wireless communication link are established via a common inductive link. According to another example embodiment, the wireless power link and the wireless communication link are established via respective inductive links. These example embodiments are provided for illustrative purposes and are not intended to be limiting. For instance, the wireless power link and the wireless communication link need not necessarily be inductive links. [0111] It should be noted that the frequency parameter may specify the resonant frequency of the portable electronic device in relative terms with respect to a reference frequency or in absolute terms. For example, the frequency parameter may specify a resonant frequency that is 5 megahertz (MHz) in relative terms by specifying the resonant frequency to be 3 MHz with respect to a reference frequency of 2 MHz. In another example, the frequency parameter may specify the same resonant frequency of 5 MHz in absolute terms to be 5 MHz, such that the resonant frequency is not specified with respect to a reference frequency. [0112] A reference frequency may be any suitable frequency. For example, a non-radiative magnetic field, which oscillates at an oscillating frequency, may mediate the wireless power transfer. For instance, the charging station may generate the non-radiative magnetic field, and power may be wirelessly transferred from the charging station to the portable electronic device through inductive coupling and/or resonant inductive coupling. In accordance with this example, the oscillating frequency at which the non-radiative magnetic field oscillates may serve as the reference frequency. [0113] At step 1106 , a determination is made whether a frequency at which a non-radiative magnetic field that mediates the wireless power transfer oscillates is substantially equal to the resonant frequency of the portable electronic device. In an example implementation, frequency comparison module 1208 determines whether the frequency at which the non-radiative magnetic field oscillates is substantially equal to the resonant frequency of the portable electronic device. If the frequency at which the non-radiative magnetic field oscillates is substantially equal to the resonant frequency of the portable electronic device, flow continues to step 1110 . Otherwise, flow continues to step 1108 . [0114] At step 1108 , the frequency at which the non-radiative magnetic field oscillates is changed to be substantially equal to the resonant frequency of the portable electronic device. In an example implementation, efficiency improvement module 1210 changes the frequency at which the non-radiative magnetic field oscillates. It will be recognized that steps 1106 and 1108 may be omitted if a non-radiative field does not mediate the wireless power transfer. [0115] At step 1110 , a determination is made whether a power parameter that specifies a magnitude of power requested by the portable electronic device is received via the wireless communication link. The power parameter may specify the magnitude of power requested by the portable electronic device in relative terms with respect to a reference magnitude of power or in absolute terms. For example, the magnitude of power provided to the portable electronic device with respect to the wireless power transfer from the charging station may serve as the reference magnitude of power. In an example implementation, parameter determination module 1206 determines whether a power parameter that specifies a magnitude requested by the portable electronic device is received via the wireless communication link. For instance, parameter receipt module 1204 may receive the power parameter. If a power parameter that specifies a magnitude of power requested by the portable electronic device is received, flow continues to step 1112 shown in FIG. 11B . Otherwise, flow continues to step 1120 shown in FIG. 11C . [0116] At step 1112 , a determination is made whether a magnitude of power that is provided by the charging station with respect to the wireless power transfer is greater than the magnitude of power requested by the portable electronic device. In an example implementation, power comparison module 1212 determines whether the magnitude of power that is provided by the charging station with respect to the wireless power transfer is greater than the magnitude of power requested by the portable electronic device. If the magnitude of power that is provided by the charging station with respect to the wireless power transfer is greater than the magnitude of power requested by the portable electronic device, flow continues to step 1114 . Otherwise, flow continues to step 1116 . [0117] At step 1114 , the magnitude of power that is provided by the charging station with respect to the wireless power transfer is reduced to be substantially equal to the magnitude of power requested by the portable electronic device. In an example implementation, efficiency improvement module 1210 reduces the magnitude of power that is provided by the charging station with respect to the wireless power transfer to be substantially equal to the magnitude of power requested by the portable electronic device. Upon completion of step 1114 , flow continues to step 1120 , which is shown in FIG. 11C . [0118] At step 1116 , a determination is made whether the magnitude of power that is provided by the charging station with respect to the wireless power transfer is less than the magnitude of power requested by the portable electronic device. In an example implementation, power comparison module 1212 determines whether the magnitude of power that is provided by the charging station with respect to the wireless power transfer is less than the magnitude of power requested by the portable electronic device. If the magnitude of power that is provided by the charging station with respect to the wireless power transfer is less than the magnitude of power requested by the portable electronic device, flow continues to step 1118 . Otherwise, flow continues to step 1120 , which is shown in FIG. 11C . [0119] At step 1118 , the magnitude of power that is provided by the charging station with respect to the wireless power transfer is increased to be substantially equal to the magnitude of power requested by the portable electronic device. In an example implementation, efficiency improvement module 1210 increases the magnitude of power that is provided by the charging station with respect to the wireless power transfer to be substantially equal to the magnitude of power requested by the portable electronic device. [0120] Persons skilled in the relevant art(s) will recognize that it may not be desirable to increase the magnitude of power that is provided by the charging station with respect to the wireless power transfer even if a determination is made that such magnitude of power is less than the magnitude of power requested by the portable electronic device. For example, efficiency of the wireless power transfer may be better served by not increasing the magnitude of power that is provided by the charging station with respect to the wireless power transfer. Accordingly, step 1118 need not necessarily be performed in response to an affirmative determination at step 1116 . [0121] Upon completion of step 1118 , flow continues to step 1120 , which is shown in FIG. 11C . At step 1120 , a determination is made whether a power parameter that specifies a magnitude of power consumed by the portable electronic device with respect to the wireless power transfer is received via the wireless communication link. The power parameter may specify the magnitude of power consumed by the portable electronic device in relative terms with respect to a reference magnitude of power or in absolute terms. For example, the magnitude of power provided to the portable electronic device with respect to the wireless power transfer from the charging station may serve as the reference magnitude of power. In an example implementation, parameter determination module 1206 determines whether a power parameter that specifies the magnitude of power consumed by the portable electronic device with respect to the wireless power transfer is received via the wireless communication link. For instance, parameter receipt module 1204 may receive the power parameter. If a power parameter that specifies the magnitude of power consumed by the portable electronic device with respect to the wireless power transfer is received, flow continues to step 1122 . Otherwise, flow continues to step 1126 . [0122] At step 1122 , a determination is made whether the magnitude of power that is provided by the charging station with respect to the wireless power transfer is greater than the magnitude of power consumed by the portable electronic device with respect to the wireless power transfer. In an example implementation, power comparison module 1212 determines whether the magnitude of power that is provided by the charging station with respect to the wireless power transfer is greater than the magnitude of power consumed by the portable electronic device with respect to the wireless power transfer. If the magnitude of power that is provided by the charging station with respect to the wireless power transfer is greater than the magnitude of power consumed by the portable electronic device with respect to the wireless power transfer, flow continues to step 1124 . Otherwise, flow continues to step 1126 . [0123] At step 1124 , the magnitude of power that is provided by the charging station with respect to the wireless power transfer is reduced to be substantially equal to the magnitude of power consumed by the portable electronic device with respect to the wireless power transfer. In an example implementation, efficiency improvement module 1210 reduces the magnitude of power that is provided by the charging station with respect to the wireless power transfer. [0124] At step 1126 , a determination is made whether a power parameter that specifies a maximum safe power that the portable electronic device is capable of consuming without substantial risk of damaging the portable electronic device is received via the wireless communication link. In an example implementation, parameter determination module 1206 determines whether a power parameter that specifies the maximum safe power is received via the wireless communication link. For instance, parameter receipt module 1204 may receive the power parameter. If a power parameter that specifies the maximum safe power is received, flow continues to step 1128 , which is shown in FIG. 11D . Otherwise, flow continues to step 1130 , which is also shown in FIG. 11D . [0125] The substantial risk of damage may be defined as a relatively high likelihood that performance of the portable electronic device will become substantially hindered, that the portable electronic device will become inoperable, or any other suitable definition. The power parameter may specify the maximum safe power in relative terms with respect to a reference magnitude of power or in absolute terms. For example, the magnitude of power provided to the portable electronic device with respect to the wireless power transfer from the charging station may serve as the reference magnitude of power. [0126] At step 1128 , the magnitude of power that is provided by the charging station with respect to the wireless power transfer is controlled to be no greater than the maximum safe power. For instance, if the magnitude of power that is provided by the charging station with respect to the wireless power transfer is greater than the maximum safe power before performance of step 1128 , the magnitude of power that is provided by the charging station with respect to the wireless power transfer may be reduced at step 1128 to be no greater than the maximum safe power. If the magnitude of power that is provided by the charging station with respect to the wireless power transfer is less than or equal to the maximum safe power before performance of step 1128 , the magnitude of power that is provided by the charging station with respect to the wireless power transfer may be maintained at step 1128 to be no greater than the maximum safe power. In an example implementation, efficiency improvement module 1210 controls the magnitude of power that is provided by the charging station with respect to the wireless power to be no greater than the maximum safe power. [0127] At step 1130 , a determination is made whether a position parameter that specifies a position of the portable electronic device is received via the wireless communication link. The position parameter may specify the position of the portable electronic device in relative terms with respect to a reference position or in absolute terms. For example, the position of the charging station may serve as the reference position. In an example implementation, parameter determination module 1206 determines whether a position parameter that specifies a position of the portable electronic device is received via the wireless communication link. If a position parameter that specifies a position of the portable electronic device is received, flow continues to step 1136 . Otherwise, flowchart 1100 ends. [0128] At step 1132 a determination is made whether an orientation of a transfer element of the charging station that generates the magnetic field for performing the wireless power transfer is optimized with respect to the position of the portable electronic device. For instance, the transfer element may be a coil through which a current is provided to generate the magnetic field for performing the wireless power transfer. In an example implementation, orientation determination module 1214 determines whether the orientation of the transfer element is optimized with respect to the position of the portable electronic device. If the orientation of the transfer element is optimized with respect to the position of the portable electronic device, flowchart 1100 ends. Otherwise, flow continues to step 1134 . [0129] At step 1134 , the orientation of the transfer element is changed based on the position parameter to increase inductive coupling between the transfer element of the charging station and a receiving element of the portable electronic device. For instance, changing the orientation of the transfer element may include but is not limited to moving the transfer element vertically, horizontally, or in another direction; rotating the transfer element; etc. In an example implementation, efficiency improvement module 1210 changes the orientation of the transfer element. It will be recognized that steps 1130 , 1132 , and 1134 may be omitted if the charging station does not generate a magnetic field for performing the wireless power transfer. [0130] In some example embodiments, one or more steps 1102 , 1104 , 1106 , 1108 , 1110 , 1112 , 1114 , 1116 , 1118 , 1120 , 1122 , 1124 , 1126 , 1128 , 1130 , 1132 , and/or 1134 of flowchart 1100 may not be performed. Moreover, steps in addition to or in lieu of steps 1102 , 1104 , 1106 , 1108 , 1110 , 1112 , 1114 , 1116 , 1118 , 1120 , 1122 , 1124 , 1126 , 1128 , 1130 , 1132 , and/or 1134 may be performed. [0131] It will be recognized that charging station 1200 may not include one or more of wireless power transfer module 1202 , parameter receipt module 1204 , parameter determination module 1206 , frequency comparison module 1208 , efficiency improvement module 1210 , power comparison module 1212 , and/or orientation determination module 1214 . Furthermore, charging station 1200 may include modules in addition to or in lieu of wireless power transfer module 1202 , parameter receipt module 1204 , parameter determination module 1206 , frequency comparison module 1208 , efficiency improvement module 1210 , power comparison module 1212 , and/or orientation determination module 1214 . [0132] FIG. 13 depicts a flowchart 1300 of a method for increasing efficiency of wireless power transfer in accordance with an embodiment described herein. Flowchart 1300 may be performed by charging station 102 , 602 , 702 , or 802 of respective wireless power transfer system 100 , 600 , 700 , or 800 shown in respective FIG. 1 , 6 , 7 , or 8 , for example. For illustrative purposes, flowchart 1300 is described with respect to a charging system 1400 shown in FIG. 14 , which is an example of a charging station 102 , 602 , 702 , or 802 , according to an embodiment. [0133] As shown in FIG. 14 , charging station 1400 includes a wireless power transfer module 1402 , a parameter analysis module 1404 , and an efficiency improvement module 1406 . Further structural and operational embodiments will be apparent to persons skilled in the relevant art(s) based on the discussion regarding flowchart 1300 . Flowchart 1300 is described as follows. [0134] As shown in FIG. 13 , the method of flowchart 1300 begins at step 1302 . In step 1302 , power is wirelessly transferred to a portable electronic device via a wireless power link. In an example implementation, wireless power transfer module 1402 wirelessly transfers the power to the portable electronic device via the wireless power link. [0135] At step 1304 , a parameter received via a wireless communication link regarding the portable electronic device with respect to the wireless transfer of the power is analyzed. For instance, the analysis may include but is not limited to comparing the parameter to a reference parameter to determine whether the parameter and the reference parameter are substantially same; comparing the parameter to a range of parameters to determine whether the parameter is within the range; comparing the parameter to a threshold to determine whether the parameter reaches the threshold; perform a mathematical operation with respect to the parameter to estimate the efficiency with respect to the wireless transfer of power; etc. In an example implementation, parameter analysis module 1404 analyzes the parameter received via the wireless communication link. [0136] At step 1306 , efficiency with respect to the wireless power transfer of the power is increased based on analysis of the parameter. In an example implementation, efficiency improvement module 1406 increases the efficiency with respect to the wireless transfer of the power. [0137] FIG. 15 depicts a flowchart 1500 of a method for increasing efficiency of wireless power transfer in accordance with an embodiment described herein. Flowchart 1500 may be performed by charging station 102 , 602 , 702 , or 802 of respective wireless power transfer system 100 , 600 , 700 , or 800 shown in respective FIG. 1 , 6 , 7 , or 8 , for example. For illustrative purposes, flowchart 1500 is described with respect to a charging system 1600 shown in FIG. 16 , which is an example of a charging station 102 , 602 , 702 , or 802 , according to an embodiment. [0138] As shown in FIG. 16 , charging station 1600 includes a wireless power transfer module 1602 , a parameter analysis module 1604 , and an efficiency improvement module 1606 . Wireless power transfer module 1602 includes a field generation module 1608 and a coupling module 1610 . Efficiency improvement module 1606 includes a field manipulation module 1612 . Further structural and operational embodiments will be apparent to persons skilled in the relevant art(s) based on the discussion regarding flowchart 1500 . Flowchart 1500 is described as follows. [0139] As shown in FIG. 15 , the method of flowchart 1500 begins at step 1502 . In step 1502 , a magnetic field is generated. In an example implementation, field generation module 1608 generates the magnetic field. For instance, field generation module 1608 may include coil through which a current is provided to generate the magnetic field. The field may be a non-radiative magnetic field, though the scope of the example embodiments is not limited in this respect. [0140] At step 1504 , power is wirelessly transferred to a portable electronic device via a wireless power link using the magnetic field. For example, the magnetic field may couple with a coil in the portable electronic device that is configured to be responsive to the magnetic field. In accordance with this example, the power may be wirelessly transferred in accordance with an inductive coupling technique, a resonant inductive coupling technique, or any other suitable technique. In an example implementation, coupling module 1610 wirelessly transfers the power to the portable electronic device. [0141] At step 1506 , a parameter received via a wireless communication link regarding the portable electronic device with respect to the wireless transfer of the power is analyzed. In an example implementation, parameter analysis module 1604 analyzes the parameter received via the wireless communication link. [0142] At step 1508 , a characteristic of the magnetic field is changed to increase efficiency with respect to the wireless transfer of the power based on analysis of the parameter. The characteristic may include but is not limited to a magnitude of the magnetic field, a directionality associated with the magnetic field, a frequency at which the magnetic field oscillates, etc. In an example implementation, field manipulation module 1612 changes the characteristic of the magnetic field to increase the efficiency with respect to the wireless transfer of the power. [0143] FIGS. 17-21 depict flowcharts 1700 , 1800 , 1900 , 2000 , and 2100 of methods for increasing efficiency of wireless power transfer in accordance with embodiments described herein. Each of flowcharts 1700 , 1800 , 1900 , 2000 , and 2100 may be performed by portable electronic device 104 , 604 , 704 , or 804 of respective wireless power transfer system 100 , 600 , 700 , or 800 shown in respective FIG. 1 , 6 , 7 , or 8 , for example. For illustrative purposes, flowcharts 1700 , 1800 , 1900 , 2000 , and 2100 are described with respect to portable electronic device 2200 shown in FIG. 22 , which is an example of a portable electronic device 104 , 604 , 704 , or 804 , according to an embodiment. [0144] As shown in FIG. 22 , portable electronic device 2200 includes a wireless power receipt module 2202 and a parameter module 2204 . Further structural and operational embodiments will be apparent to persons skilled in the relevant art(s) based on the discussion regarding flowcharts 1700 , 1800 , 1900 , 2000 , and 2100 . Flowcharts 1700 , 1800 , 1900 , 2000 , and 2100 are described in the following discussion. [0145] As shown in FIG. 17 , the method of flowchart 1700 begins at step 1702 . In step 1702 , power is wirelessly received for a first period of time at a portable electronic device from a charging station via a wireless power link having a first transmission efficiency. Wirelessly receiving power for the first period of time may be performed in accordance with an inductive coupling technique, a resonant inductive coupling technique, or any other suitable technique. In an example implementation, wireless power receipt module 2202 wirelessly receives power for the first period of time. [0146] At step 1704 , at least one parameter regarding the portable electronic device with respect to receipt of power during the first period of time is provided to the charging station via a wireless communication link. For instance, the at least one parameter may be provided to the charging station via the wireless communication link in accordance with a Near Field Communication (NFC) protocol, a Bluetooth™ protocol, a ZigBee® protocol, an IEEE 802.11 protocol, or any other suitable protocol. The wireless power link and the wireless communication link may be implemented as separate links or as a common link. The wireless power link and the wireless communication link may be inductive links, though the scope of the example embodiments is not limited in this respect. In an example implementation, parameter module 2204 provides the at least one parameter to the charging station. [0147] At step 1706 , power is wirelessly received for a second period of time at the portable electronic device from the charging station via the wireless power link having a second transmission efficiency that is greater than the first transmission efficiency in response to providing the at least one parameter to the charging station. Wirelessly receiving power for the second period of time may be performed in accordance with an inductive coupling technique, a resonant inductive coupling technique, or any other suitable technique. In an example implementation, wireless power receipt module 2202 wirelessly receives power for the second period of time. [0148] As shown in FIG. 18 , the method of flowchart 1800 begins at step 1802 . In step 1802 , power is wirelessly received for a first period of time at a portable electronic device from a charging station via a wireless power link having a first transmission efficiency. In an example implementation, wireless power receipt module 2202 wirelessly receives power for the first period of time. [0149] At step 1804 , a frequency parameter that specifies a resonant frequency of the portable electronic device is provided to charging station via a wireless communication link. The frequency parameter may specify the resonant frequency in relative terms with respect to a reference frequency or in absolute terms. In an example implementation, parameter module 2204 provides the frequency parameter to the charging station. [0150] At step 1806 , power is wirelessly received for a second period of time at the portable electronic device from the charging station via the wireless power link having a second transmission efficiency that is greater than the first transmission efficiency in response to providing the frequency parameter to the charging station. The first efficiency is based on resonant inductive coupling of a first coil in the portable electronic device with a second coil in the charging station that generates a non-radiative magnetic field oscillating at a first frequency that is not substantially same as the resonant frequency of the portable electronic device. The second efficiency is based on resonant inductive coupling of the first coil in the portable electronic device with the second coil in the charging station that generates a non-radiative magnetic field oscillating at a second frequency that is substantially same as the resonant frequency of the portable electronic device. In an example implementation, wireless power receipt module 2202 wirelessly receives power for the second period of time. [0151] As shown in FIG. 19 , the method of flowchart 1900 begins at step 1902 . In step 1902 , a magnitude of power that is greater than a reference magnitude of power is wirelessly received for a first period of time at a portable electronic device from a charging station via a wireless power link having a first transmission efficiency. In an example implementation, wireless power receipt module 2202 wirelessly receives the magnitude of power that is greater than the reference magnitude of power for the first period of time. [0152] At step 1904 , a power parameter is provided to the charging station via a wireless communication link. The power parameter specifies the reference magnitude of power as being requested by the portable electronic device. The power parameter may specify the reference magnitude of power in relative terms with respect to a second reference magnitude of power or in absolute terms. For example, the magnitude of power wirelessly received for the first period of time at the portable electronic device may serve as the second reference magnitude of power. In an example implementation, parameter module 2204 provides the power parameter to the charging station. [0153] At step 1906 , a magnitude of power that is substantially same as the reference magnitude of power is wirelessly received for a second period of time at the portable electronic device from the charging station via the wireless power link having a second transmission efficiency that is greater than the first transmission efficiency in response to providing the power parameter to the charging station. In an example implementation, wireless power receipt module 2202 wirelessly receives the magnitude of power that is substantially same as the reference magnitude of power for the second period of time. [0154] As shown in FIG. 20 , the method of flowchart 2000 begins at step 2002 . In step 2002 , a magnitude of power is wirelessly received at a portable electronic device for a first period of time from a charging station via a wireless power link having a first transmission efficiency. The magnitude of power wirelessly received for the first period of time is greater than a magnitude of power consumed by the portable electronic device for the first period of time. In an example implementation, wireless power receipt module 2202 wirelessly receives the magnitude of power for the first period of time. [0155] At step 2004 , a power parameter that specifies the magnitude of power consumed by the portable electronic device during the first period of time is provided to the charging station via a wireless communication link. The power parameter may specify the magnitude of power consumed by the portable electronic device during the first period of time in relative terms with respect to a reference magnitude of power or in absolute terms. For example, the magnitude of power wirelessly received at the portable electronic device for the first period of time may serve as the reference magnitude of power. In an example implementation, parameter module 2204 provides the power parameter to the charging station. [0156] At step 2006 , a magnitude of power is wirelessly received at the portable electronic device for a second period of time from the charging station via the wireless power link having a second transmission efficiency that is greater than the first transmission efficiency in response to providing the power parameter to the charging station. The magnitude of power wirelessly received for the second period of time is substantially same as the magnitude of power consumed by the portable electronic device for the second period of time. In an example implementation, wireless power receipt module 2202 wirelessly receives the magnitude of power for the second period of time. [0157] As shown in FIG. 21 , the method of flowchart 2100 begins at step 2102 . In step 2102 , a magnitude of power that is greater than a maximum safe power, which a portable electronic device is capable of consuming without substantial risk of damaging the portable electronic device, is wirelessly received for a first period of time at the portable electronic device from a charging station via a wireless power link having a first transmission efficiency. In an example implementation, wireless power receipt module 2202 wirelessly receives the magnitude of power for the first period of time. [0158] At step 2104 , a power parameter that specifies the maximum safe power is provided to the charging station via a wireless communication link. The power parameter may specify the maximum safe power in relative terms with respect to a reference magnitude of power or in absolute terms. For example, the magnitude of power wirelessly received for the first period of time at the portable electronic device may serve as the reference magnitude of power. In an example implementation, parameter module 2204 provides the power parameter that specifies the maximum safe power to the charging station. [0159] At step 2106 , a magnitude of power that is no greater than the maximum safe power is wirelessly received for a second period of time at the portable electronic device from the charging station via the wireless power link having a second transmission efficiency that is greater than the first transmission efficiency in response to providing the power parameter to the charging station. In an example implementation, wireless power receipt module 2202 wirelessly receives the magnitude of power for the second period of time. V. Conclusion [0160] While various embodiments have been described above, it should be understood that they have been presented by way of example only, and not limitation. It will be understood by those skilled in the relevant art(s) that various changes in form and details may be made to the embodiments described herein without departing from the spirit and scope of the invention as defined in the appended claims. Accordingly, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.

Techniques are described herein that are capable of increasing efficiency of wireless power transfer. A wireless power transfer system includes features that allow the system to be deployed in public spaces such as airports or in commercial establishments such as restaurants or hotels to allow a user to recharge one or more portable electronic devices while away from home. To accommodate wireless recharging of a variety of device types and states, the system may receive parameters and/or state information associated with a portable electronic device to be recharged and may control the wireless power transfer in accordance with such parameters and/or state information. For instance, the system may increase efficiency of the wireless power transfer based on such parameters and/or state information. The system may also provide a secure and efficient means for obtaining required payment information from the user prior to the wireless power transfer, thereby facilitating fee-based recharging.

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] The present application is a continuation of U.S. patent application Ser. No. 12/777,892, filed May 11, 2010, which is a continuation of U.S. patent application Ser. No. 11/782,451, filed Jul. 24, 2007, now abandoned, which is a divisional of U.S. patent application Ser. No. 11/129,765, filed May 13, 2005, now U.S. Pat. No. 7,653,438, which claims the benefit of U.S. Provisional Patent Application No. 60/616,254, filed Oct. 5, 2004; and U.S. Provisional Patent Application No. 60/624,793, filed Nov. 2, 2004. [0002] U.S. patent application Ser. No. 11/129,765, filed May 13, 2005, now U.S. Pat. No. 7,653,438 is also a continuation-in-part of U.S. patent application Ser. No. 10/408,665, filed Apr. 8, 2003, now U.S. Pat. No. 7,162,303, which claims the benefit of U.S. Provisional Patent Application Nos. (a) 60/370,190, filed Apr. 8, 2002; (b) 60/415,575, filed Oct. 3, 2002; and (c) 60/442,970, filed Jan. 29, 2003. The disclosures of these applications are incorporated herein by reference in their entireties. INCORPORATION BY REFERENCE [0003] All publications and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference. TECHNICAL FIELD [0004] The present invention relates to methods and apparatus for renal neuromodulation. More particularly, the present invention relates to methods and apparatus for achieving renal neuromodulation via a pulsed electric field and/or electroporation or electrofusion. BACKGROUND [0005] Congestive Heart Failure (“CHF”) is a condition that occurs when the heart becomes damaged and reduces blood flow to the organs of the body. If blood flow decreases sufficiently, kidney function becomes impaired and results in fluid retention, abnormal hormone secretions and increased constriction of blood vessels. These results increase the workload of the heart and further decrease the capacity of the heart to pump blood through the kidney and circulatory system. [0006] This reduced capacity further reduces blood flow to the kidney, which in turn further reduces the capacity of the heart. It is believed that progressively decreasing perfusion of the kidney is a principal non-cardiac cause perpetuating the downward spiral of CHF. Moreover, the fluid overload and associated clinical symptoms resulting from these physiologic changes are predominant causes for excessive hospital admissions, terrible quality of life and overwhelming costs to the health care system due to CHF. [0007] While many different diseases may initially damage the heart, once present, CHF is split into two types: Chronic CHF and Acute (or Decompensated-Chronic) CHF. Chronic Congestive Heart Failure is a longer term, slowly progressive, degenerative disease. Over years, chronic congestive heart failure leads to cardiac insufficiency. Chronic CHF is clinically categorized by the patient's ability to exercise or perform normal activities of daily living (such as defined by the New York Heart Association Functional Class). Chronic CHF patients are usually managed on an outpatient basis, typically with drugs. [0008] Chronic CHF patients may experience an abrupt, severe deterioration in heart function, termed Acute Congestive Heart Failure, resulting in the inability of the heart to maintain sufficient blood flow and pressure to keep vital organs of the body alive. These Acute CHF deteriorations can occur when extra stress (such as an infection or excessive fluid overload) significantly increases the workload on the heart in a stable chronic CHF patient. In contrast to the stepwise downward progression of chronic CHF, a patient suffering acute CHF may deteriorate from even the earliest stages of CHF to severe hemodynamic collapse. In addition, Acute CHF can occur within hours or days following an Acute Myocardial Infarction (“AMI”), which is a sudden, irreversible injury to the heart muscle, commonly referred to as a heart attack. [0009] As mentioned, the kidneys play a significant role in the progression of CHF, as well as in Chronic Renal Failure (“CRF”), End-Stage Renal Disease (“ESRD”), hypertension (pathologically high blood pressure) and other cardio-renal diseases. The functions of the kidney can be summarized under three broad categories: filtering blood and excreting waste products generated by the body's metabolism; regulating salt, water, electrolyte and acid-base balance; and secreting hormones to maintain vital organ blood flow. Without properly functioning kidneys, a patient will suffer water retention, reduced urine flow and an accumulation of waste toxins in the blood and body. These conditions resulting from reduced renal function or renal failure (kidney failure) are believed to increase the workload of the heart. In a CHF patient, renal failure will cause the heart to further deteriorate as the water build-up and blood toxins accumulate due to the poorly functioning kidneys and, in turn, cause the heart further harm. [0010] The primary functional unit of the kidneys that is involved in urine formation is called the “nephron”. Each kidney consists of about one million nephrons. The nephron is made up of a glomerulus and its tubules, which can be separated into a number of sections: the proximal tubule, the medullary loop (loop of Henle), and the distal tubule. Each nephron is surrounded by different types of cells that have the ability to secrete several substances and hormones (such as renin and erythropoietin). Urine is formed as a result of a complex process starting with the filtration of plasma water from blood into the glomerulus. The walls of the glomerulus are freely permeable to water and small molecules but almost impermeable to proteins and large molecules. Thus, in a healthy kidney, the filtrate is virtually free of protein and has no cellular elements. The filtered fluid that eventually becomes urine flows through the tubules. The final chemical composition of the urine is determined by the secretion into, and re-absorption of substances from, the urine required to maintain homeostasis. [0011] Receiving about 20% of cardiac output, the two kidneys filter about 125 ml of plasma water per minute. Filtration occurs because of a pressure gradient across the glomerular membrane. The pressure in the arteries of the kidney pushes plasma water into the glomerulus causing filtration. To keep the Glomerulur Filtration Rate (“GFR”) relatively constant, pressure in the glomerulus is held constant by the constriction or dilatation of the afferent and efferent arterioles, the muscular walled vessels leading to and from each glomerulus. [0012] In a CHF patient, the heart will progressively fail, and blood flow and pressure will drop in the patient's circulatory system. During acute heart failure, short-term compensations serve to maintain perfusion to critical organs, notably the brain and the heart that cannot survive prolonged reduction in blood flow. However, these same responses that initially aid survival during acute heart failure become deleterious during chronic heart failure. [0013] A combination of complex mechanisms contribute to deleterious fluid overload in CHF. As the heart fails and blood pressure drops, the kidneys cannot function and become impaired due to insufficient blood pressure for perfusion. This impairment in renal function ultimately leads to the decrease in urine output. Without sufficient urine output, the body retains fluids, and the resulting fluid overload causes peripheral edema (swelling of the legs), shortness of breath (due to fluid in the lungs), and fluid retention in the abdomen, among other undesirable conditions in the patient. [0014] In addition, the decrease in cardiac output leads to reduced renal blood flow, increased neurohormonal stimulus, and release of the hormone renin from the juxtaglomerular apparatus of the kidney. This results in avid retention of sodium and, thus, volume expansion. Increased renin results in the formation of angiotensin, a potent vasoconstrictor. Heart failure and the resulting reduction in blood pressure also reduce the blood flow and perfusion pressure through organs in the body other than the kidneys. As they suffer reduced blood pressure, these organs may become hypoxic, resulting in a metabolic acidosis that reduces the effectiveness of pharmacological therapy and increases a risk of sudden death. [0015] This spiral of deterioration that physicians observe in heart failure patients is believed to be mediated, at least in part, by activation of a subtle interaction between heart function and kidney function, known as the renin-angiotensin system. Disturbances in the heart's pumping function results in decreased cardiac output and diminished blood flow. The kidneys respond to the diminished blood flow as though the total blood volume was decreased, when in fact the measured volume is normal or even increased. This leads to fluid retention by the kidneys and formation of edema, thereby causing the fluid overload and increased stress on the heart. [0016] Systemically, CHF is associated with an abnormally elevated peripheral vascular resistance and is dominated by alterations of the circulation resulting from an intense disturbance of sympathetic nervous system function. Increased activity of the sympathetic nervous system promotes a downward vicious cycle of increased arterial vasoconstriction (increased resistance of vessels to blood flow) followed by a further reduction of cardiac output, causing even more diminished blood flow to the vital organs. [0017] In CHF via the previously explained mechanism of vasoconstriction, the heart and circulatory system dramatically reduce blood flow to the kidneys. During CHF, the kidneys receive a command from higher neural centers via neural pathways and hormonal messengers to retain fluid and sodium in the body. In response to stress on the heart, the neural centers command the kidneys to reduce their filtering functions. While in the short term, these commands can be beneficial, if these commands continue over hours and days they can jeopardize the person's life or make the person dependent on artificial kidney for life by causing the kidneys to cease functioning. [0018] When the kidneys do not fully filter the blood, a huge amount of fluid is retained in the body, which results in bloating (fluid retention in tissues) and increases the workload of the heart. Fluid can penetrate into the lungs, and the patient becomes short of breath. This odd and self-destructive phenomenon is most likely explained by the effects of normal compensatory mechanisms of the body that improperly perceive the chronically low blood pressure of CHF as a sign of temporary disturbance, such as bleeding. [0019] In an acute situation, the body tries to protect its most vital organs, the brain and the heart, from the hazards of oxygen deprivation. Commands are issued via neural and hormonal pathways and messengers. These commands are directed toward the goal of maintaining blood pressure to the brain and heart, which are treated by the body as the most vital organs. The brain and heart cannot sustain low perfusion for any substantial period of time. A stroke or a cardiac arrest will result if the blood pressure to these organs is reduced to unacceptable levels. Other organs, such as the kidneys, can withstand somewhat longer periods of ischemia without suffering long-term damage. Accordingly, the body sacrifices blood supply to these other organs in favor of the brain and the heart. [0020] The hemodynamic impairment resulting from CHF activates several neurohormonal systems, such as the renin-angiotensin and aldosterone system, sympatho-adrenal system and vasopressin release. As the kidneys suffer from increased renal vasoconstriction, the GFR drops, and the sodium load in the circulatory system increases. Simultaneously, more renin is liberated from the juxtaglomerular of the kidney. The combined effects of reduced kidney functioning include reduced glomerular sodium load, an aldosterone-mediated increase in tubular reabsorption of sodium, and retention in the body of sodium and water. These effects lead to several signs and symptoms of the CHF condition, including an enlarged heart, increased systolic wall stress, an increased myocardial oxygen demand, and the formation of edema on the basis of fluid and sodium retention in the kidney. Accordingly, sustained reduction in renal blood flow and vasoconstriction is directly responsible for causing the fluid retention associated with CHF. [0021] CHF is progressive, and as of now, not curable. The limitations of drug therapy and its inability to reverse or even arrest the deterioration of CHF patients are clear. Surgical therapies are effective in some cases, but limited to the end-stage patient population because of the associated risk and cost. Furthermore, the dramatic role played by kidneys in the deterioration of CHF patients is not adequately addressed by current surgical therapies. [0022] The autonomic nervous system is recognized as an important pathway for control signals that are responsible for the regulation of body functions critical for maintaining vascular fluid balance and blood pressure. The autonomic nervous system conducts information in the form of signals from the body's biologic sensors such as baroreceptors (responding to pressure and volume of blood) and chemoreceptors (responding to chemical composition of blood) to the central nervous system via its sensory fibers. It also conducts command signals from the central nervous system that control the various innervated components of the vascular system via its motor fibers. [0023] Experience with human kidney transplantation provided early evidence of the role of the nervous system in kidney function. It was noted that after transplant, when all the kidney nerves were totally severed, the kidney increased the excretion of water and sodium. This phenomenon was also observed in animals when the renal nerves were cut or chemically destroyed. The phenomenon was called “denervation diuresis” since the denervation acted on a kidney similar to a diuretic medication. Later the “denervation diuresis” was found to be associated with vasodilatation of the renal arterial system that led to increased blood flow through the kidney. This observation was confirmed by the observation in animals that reducing blood pressure supplying the kidneys reversed the “denervation diuresis”. [0024] It was also observed that after several months passed after the transplant surgery in successful cases, the “denervation diuresis” in transplant recipients stopped and the kidney function returned to normal. Originally, it was believed that the “renal diuresis” was a transient phenomenon and that the nerves conducting signals from the central nervous system to the kidney were not essential to kidney function. Later discoveries suggested that the renal nerves had a profound ability to regenerate and that the reversal of “denervation diuresis” could be attributed to the growth of new nerve fibers supplying the kidneys with necessary stimuli. [0025] Another body of research focused on the role of the neural control of secretion of the hormone renin by the kidney. As was discussed previously, renin is a hormone responsible for the “vicious cycle” of vasoconstriction and water and sodium retention in heart failure patients. It was demonstrated that an increase or decrease in renal sympathetic nerve activity produced parallel increases and decreases in the renin secretion rate by the kidney, respectively. [0026] In summary, it is known from clinical experience and the large body of animal research that an increase in renal sympathetic nerve activity leads to vasoconstriction of blood vessels supplying the kidney, decreased renal blood flow, decreased removal of water and sodium from the body, and increased renin secretion. It is also known that reduction of sympathetic renal nerve activity, e.g., via denervation, may reverse these processes. [0027] It has been established in animal models that the heart failure condition results in abnormally high sympathetic stimulation of the kidney. This phenomenon was traced back to the sensory nerves conducting signals from baroreceptors to the central nervous system. Baroreceptors are present in the different locations of the vascular system. Powerful relationships exist between baroreceptors in the carotid arteries (supplying the brain with arterial blood) and sympathetic nervous stimulus to the kidneys. When arterial blood pressure was suddenly reduced in experimental animals with heart failure, sympathetic tone increased. Nevertheless, the normal baroreflex likely is not solely responsible for elevated renal nerve activity in chronic CHF patients. If exposed to a reduced level of arterial pressure for a prolonged time, baroreceptors normally “reset”, i.e., return to a baseline level of activity, until a new disturbance is introduced. Therefore, it is believed that in chronic CHF patients, the components of the autonomic-nervous system responsible for the control of blood pressure and the neural control of the kidney function become abnormal. The exact mechanisms that cause this abnormality are not fully understood, but its effects on the overall condition of the CHF patients are profoundly negative. [0028] End-Stage Renal Disease is another condition at least partially controlled by renal neural activity. There has been a dramatic increase in patients with ESRD due to diabetic nephropathy, chronic glomerulonephritis and uncontrolled hypertension. Chronic Renal Failure slowly progresses to ESRD. CRF represents a critical period in the evolution of ESRD. The signs and symptoms of CRF are initially minor, but over the course of 2-5 years, become progressive and irreversible. While some progress has been made in combating the progression to, and complications of, ESRD, the clinical benefits of existing interventions remain limited. [0029] It has been known for several decades that renal diseases of diverse etiology (hypotension, infection, trauma, autoimmune disease, etc.) can lead to the syndrome of CRF characterized by systemic hypertension, proteinuria (excess protein filtered from the blood into the urine) and a progressive decline in GFR ultimately resulting in ESRD. These observations suggest that CRF progresses via a common pathway of mechanisms and that therapeutic interventions inhibiting this common pathway may be successful in slowing the rate of progression of CRF irrespective of the initiating cause. [0030] To start the vicious cycle of CRF, an initial insult to the kidney causes loss of some nephrons. To maintain normal GFR, there is an activation of compensatory renal and systemic mechanisms resulting in a state of hyperfiltration in the remaining nephrons. Eventually, however, the increasing numbers of nephrons “overworked” and damaged by hyperfiltration are lost. At some point, a sufficient number of nephrons are lost so that normal GFR can no longer be maintained. These pathologic changes of CRF produce worsening systemic hypertension, thus high glomerular pressure and increased hyperfiltration. Increased glomerular hyperfiltration and permeability in CRF pushes an increased amount of protein from the blood, across the glomerulus and into the renal tubules. This protein is directly toxic to the tubules and leads to further loss of nephrons, increasing the rate of progression of CRF. This vicious cycle of CRF continues as the GFR drops with loss of additional nephrons leading to further hyperfiltration and eventually to ESRD requiring dialysis. Clinically, hypertension and excess protein filtration have been shown to be two major determining factors in the rate of progression of CRF to ESRD. [0031] Though previously clinically known, it was not until the 1980s that the physiologic link between hypertension, proteinuria, nephron loss and CRF was identified. In 1990s the role of sympathetic nervous system activity was elucidated. Afferent signals arising from the damaged kidneys due to the activation of mechanoreceptors and chemoreceptors stimulate areas of the brain responsible for blood pressure control. In response, the brain increases sympathetic stimulation on the systemic level, resulting in increased blood pressure primarily through vasoconstriction of blood vessels. When elevated sympathetic stimulation reaches the kidney via the efferent sympathetic nerve fibers, it produces major deleterious effects in two forms. The kidneys are damaged by direct renal toxicity from the release of sympathetic neurotransmitters (such as norepinephrine) in the kidneys independent of the hypertension. Furthermore, secretion of renin that activates Angiotensin II is increased, which increases systemic vasoconstriction and exacerbates hypertension. [0032] Over time, damage to the kidneys leads to a further increase of afferent sympathetic signals from the kidney to the brain. Elevated Angiotensin II further facilitates internal renal release of neurotransmitters. The feedback loop is therefore closed, which accelerates deterioration of the kidneys. [0033] In view of the foregoing, it would be desirable to provide methods and apparatus for the treatment of congestive heart failure, renal disease, hypertension and/or other cardio-renal diseases via renal neuromodulation and/or denervation. SUMMARY [0034] The present invention provides methods and apparatus for renal neuromodulation (e.g., denervation) using a pulsed electric field (PEF). Several aspects of the invention apply a pulsed electric field to effectuate electroporation and/or electrofusion in renal nerves, other neural fibers that contribute to renal neural function, or other neural features. Several embodiments of the invention are intravascular devices for inducing renal neuromodulation. The apparatus and methods described herein may utilize any suitable electrical signal or field parameters that achieve neuromodulation, including denervation, and/or otherwise create an electroporative and/or electrofusion effect. For example, the electrical signal may incorporate a nanosecond pulsed electric field (nsPEF) and/or a PEF for effectuating electroporation. One specific embodiment comprises applying a first course of PEF electroporation followed by a second course of nsPEF electroporation to induce apoptosis in any cells left intact after the PEF treatment, or vice versa. An alternative embodiment comprises fusing nerve cells by applying a PEF in a manner that is expected to reduce or eliminate the ability of the nerves to conduct electrical impulses. When the methods and apparatus are applied to renal nerves and/or other neural fibers that contribute to renal neural functions, this present inventors believe that urine output will increase and/or blood pressure will be controlled in a manner that will prevent or treat CHF, hypertension, renal system diseases, and other renal anomalies. [0035] Several aspects of particular embodiments can achieve such results by selecting suitable parameters for the PEFs and/or nsPEFs. Pulsed electric field parameters can include, but are not limited to, field strength, pulse width, the shape of the pulse, the number of pulses and/or the interval between pulses (e.g., duty cycle). Suitable field strengths include, for example, strengths of up to about 10,000 V/cm. Suitable pulse widths include, for example, widths of up to about 1 second. Suitable shapes of the pulse waveform include, for example, AC waveforms, sinusoidal waves, cosine waves, combinations of sine and cosine waves, DC waveforms, DC-shifted AC waveforms, RF waveforms, square waves, trapezoidal waves, exponentially-decaying waves, combinations thereof, etc. Suitable numbers of pulses include, for example, at least one pulse. Suitable pulse intervals include, for example, intervals less than about 10 seconds. Any combination of these parameters may be utilized as desired. These parameters are provided for the sake of illustration and should in no way be considered limiting. Additional and alternative waveform parameters will be apparent. [0036] Several embodiments are directed to percutaneous intravascular systems for providing long-lasting denervation to minimize acute myocardial infarct (“AMI”) expansion and for helping to prevent the onset of morphological changes that are affiliated with congestive heart failure. For example, one embodiment of the invention comprises treating a patient for an infarction, e.g., via coronary angioplasty and/or stenting, and performing an intra-arterial pulsed electric field renal denervation procedure under fluoroscopic guidance. Alternatively, PEF therapy could be delivered in a separate session soon after the AMI had been stabilized. Renal neuromodulation also may be used as an adjunctive therapy to renal surgical procedures. In these embodiments, the anticipated increase in urine output and/or control of blood pressure provided by the renal PEF therapy is expected to reduce the load on the heart to inhibit expansion of the infarct and prevent CHF. [0037] Several embodiments of intravascular pulsed electric field systems described herein may denervate or reduce the activity of the renal nervous supply immediately post-infarct, or at any time thereafter, without leaving behind a permanent implant in the patient. These embodiments are expected to increase urine output and/or control blood pressure for a period of several months during which the patient's heart can heal. If it is determined that repeat and/or chronic neuromodulation would be beneficial after this period of healing, renal PEF treatment can be repeated as needed. [0038] In addition to efficaciously treating AMI, several embodiments of systems described herein are also expected to treat CHF, hypertension, renal failure, and other renal or cardio-renal diseases influenced or affected by increased renal sympathetic nervous activity. For example, the systems may be used to treat CHF at any time by advancing the PEF system to a treatment site via a vascular structure and then delivering a PEF therapy to the treatment site. This may, for example, modify a level of fluid offload. [0039] Embodiments of intravascular PEF systems described herein may be used similarly to angioplasty or electrophysiology catheters which are well known in the art. For example, arterial access may be gained through a standard Seldinger Technique, and an arterial sheath optionally may be placed to provide catheter access. A guidewire may be advanced through the vasculature and into the renal artery of the patient, and then an intravascular PEF may be advanced over the guidewire and/or through the sheath into the renal artery. The sheath optionally may be placed before inserting the PEF catheter or advanced along with the PEF catheter such that the sheath partially or completely covers the catheter. Alternatively, the PEF catheter may be advanced directly through the vasculature without the use of a guide wire and/or introduced and advanced into the vasculature without a sheath. [0040] In addition to arterial placement, the PEF system may be placed within a vein. Venous access may, for example, be achieved via a jugular approach. PEF systems may be utilized, for example, within the renal artery, within the renal vein or within both the renal artery and the renal vein to facilitate more complete denervation. [0041] After the PEF catheter is positioned within the vessel at a desired location with respect to the target neurons, it is stabilized within the vessel (e.g., braced against the vessel wall) and energy is delivered to the target nerve or neurons. In one variation, pulsed RF energy is delivered to the target to create a non-thermal nerve block, reduce neural signaling, or otherwise modulate neural activity. Alternatively or additionally, cooling, cryogenic, thermal RF, thermal or non-thermal microwave, focused or unfocused ultrasound, thermal or non-thermal DC, as well as any combination thereof, may be employed to reduce or otherwise control neural signaling. [0042] In still other embodiments of the invention, other non-renal neural structures may be targeted from within arterial or venous conduits in addition to or in lieu of renal neural structures. For instance, a PEF catheter can be navigated through the aorta or the vena cava and brought into apposition with various neural structures to treat other conditions or augment the treatment of renal-cardiac conditions. For example, nerve bodies of the lumbar sympathetic chain may be accessed and modulated, blocked or ablated, etc., in this manner. [0043] Several embodiments of the PEF systems may completely block or denervate the target neural structures, or the PEF systems may otherwise modulate the renal nervous activity. As opposed to a full neural blockade such as denervation, other neuromodulation produces a less-than-complete change in the level of renal nervous activity between the kidney(s) and the rest of the body. Accordingly, varying the pulsed electric field parameters will produce different effects on the nervous activity. [0044] In one embodiment of an intravascular pulsed electric field system, the device includes one or more electrodes that are configured to physically contact a target region of a renal vasculature for delivery of a pulsed electric field. For example, the device can comprise a catheter having an expandable helical section and one or more electrodes at the helical section. The catheter may be positioned in the renal vasculature while in a low profile configuration. The expandable section can then be expanded to contact the inner surface of the vessel wall. Alternatively, the catheter can have one or more expandable helical electrodes. For example, first and second expandable electrodes may be positioned within the vessel at a desired distance from one another to provide an active electrode and a return electrode. The expandable electrodes may comprise shape-memory materials, inflatable balloons, expandable meshes, linkage systems and other types of devices that can expand in a controlled manner. Suitable expandable linkage systems include expandable baskets, having a plurality of shape-memory wires or slotted hypotubes, and/or expandable rings. Additionally, the expandable electrodes may be point contact electrodes arranged along a balloon portion of a catheter. [0045] Other embodiments of pulsed electric field systems include electrodes that do not physically contact the vessel wall. RF energy, both traditional thermal energy and relatively non-thermal pulsed RF, are examples of pulsed electric fields that can be conducted into tissue to be treated from a short distance away from the tissue itself. Other types of pulsed electric fields can also be used in situations in which the electrodes do not physically contact the vessel wall. As such, the pulsed electric fields can be applied directly to the nerve via physical contact between the electrode contacts and the vessel wall or other tissue, or the pulsed electric fields can be applied indirectly to the nerve without physically contacting the electrode contacts with the vessel wall. The term “nerve contact” accordingly includes physical contact of a system element with the nerve and/or tissue proximate to the nerve, and also electrical contact alone without physically contacting the nerve or tissue. To indirectly apply the pulsed electrical field, the device has a centering element configured to position the electrodes in a central region of the vessel or otherwise space the electrodes apart from the vessel wall. The centering element may comprise, for example, a balloon or an expandable basket. One or more electrodes may be positioned on a central shaft of the centering element—either longitudinally aligned with the element or positioned on either side of the element. When utilizing a balloon catheter, the inflated balloon may act as an insulator of increased impedance for orienting or directing a pulsed electric field along a desired electric flow path. As will be apparent, alternative insulators may be utilized. [0046] In another embodiment of the system, a combination apparatus includes an intravascular catheter having a first electrode configured to physically contact the vessel wall and a second electrode configured to be positioned within the vessel but spaced apart from the vessel wall. For example, an expandable helical electrode may be used in combination with a centrally-disposed electrode to provide such a bipolar electrode pair. [0047] In yet another embodiment, a radial position of one or more electrodes relative to a vessel wall may be altered dynamically to focus the pulsed electric field delivered by the electrode(s). In still another variation, the electrodes may be configured for partial or complete passage across the vessel wall. For example, the electrode(s) may be positioned within the renal vein, then passed across the wall of the renal vein into the perivascular space such that they at least partially encircle the renal artery and/or vein prior to delivery of a pulsed electric field. [0048] Bipolar embodiments of the present invention may be configured for dynamic movement or operation relative to a spacing between the active and ground electrodes to achieve treatment over a desired distance, volume or other dimension. For example, a plurality of electrodes may be arranged such that a bipolar pair of electrodes can move longitudinally relative to each other for adjusting the separation distance between the electrodes and/or for altering the location of treatment. One specific embodiment includes a first electrode coupled to a catheter and a moveable second electrode that can move through a lumen of the catheter. In alternative embodiments, a first electrode can be attached to a catheter and a second electrode can be attached to an endoluminally-delivered device such that the first and second electrodes may be repositioned relative to one another to alter a separation distance between the electrodes. Such embodiments may facilitate treatment of a variety of renal vasculature anatomies. [0049] Any of the embodiments of the present invention described herein optionally may be configured for infusing agents into the treatment area before, during or after energy application. The infused agents can be selected to enhance or modify the neuromodulatory effect of the energy application. The agents can also protect or temporarily displace non-target cells, and/or facilitate visualization. [0050] Several embodiments of the present invention may comprise detectors or other elements that facilitate identification of locations for treatment and/or that measure or confirm the success of treatment. For example, the system can be configured to also deliver stimulation waveforms and monitor physiological parameters known to respond to stimulation of the renal nerves. Based on the results of the monitored parameters, the system can determine the location of renal nerves and/or whether denervation has occurred. Detectors for monitoring of such physiological responses include, for example, Doppler elements, thermocouples, pressure sensors, and imaging modalities (e.g., fluoroscopy, intravascular ultrasound, etc.). Alternatively, electroporation may be monitored directly using, for example, Electrical Impedance Tomography (“EIT”) or other electrical impedance measurements. Additional monitoring techniques and elements will be apparent. Such detector(s) may be integrated with the PEF systems or they may be separate elements. [0051] Still other specific embodiments include electrodes configured to align the electric field with the longer dimension of the target cells. For instance, nerve cells tend to be elongate structures with lengths that greatly exceed their lateral dimensions (e.g., diameter). By aligning an electric field so that the directionality of field propagation preferentially affects the longitudinal aspect of the cell rather than the lateral aspect of the cell, it is expected that lower field strengths can to be used to kill or disable target cells. This is expected to conserve the battery life of implantable devices, reduce collateral effects on adjacent structures, and otherwise enhance the ability to modulate the neural activity of target cells. [0052] Other embodiments of the invention are directed to applications in which the longitudinal dimensions of cells in tissues overlying or underlying the nerve are transverse (e.g., orthogonal or otherwise at an angle) with respect to the longitudinal direction of the nerve cells. Another aspect of these embodiments is to align the directionality of the PEF such that the field aligns with the longer dimensions of the target cells and the shorter dimensions of the non-target cells. More specifically, arterial smooth muscle cells are typically elongate cells which surround the arterial circumference in a generally spiraling orientation so that their longer dimensions are circumferential rather than running longitudinally along the artery. Nerves of the renal plexus, on the other hand, run along the outside of the artery generally in the longitudinal direction of the artery. Therefore, applying a PEF which is generally aligned with the longitudinal direction of the artery is expected to preferentially cause electroporation in the target nerve cells without affecting at least some of the non-target arterial smooth muscle cells to the same degree. This may enable preferential denervation of nerve cells (target cells) in the adventitia or periarterial region from an intravascular device without affecting the smooth muscle cells of the vessel to an undesirable extent. BRIEF DESCRIPTION OF THE DRAWINGS [0053] Several embodiments of the present invention will be apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout, and in which: [0054] FIG. 1 is a schematic view illustrating human renal anatomy. [0055] FIG. 2 is a schematic detail view showing the location of the renal nerves relative to the renal artery. [0056] FIGS. 3A and 3B are schematic side- and end-views, respectively, illustrating a direction of electrical current flow for selectively affecting renal nerves. [0057] FIG. 4 is a schematic side-view, partially in section, of an intravascular catheter having a plurality of electrodes in accordance with one embodiment of the invention. [0058] FIG. 5 is a schematic side-view, partially in section, of an intravascular device having a pair of expanding helical electrodes arranged at a desired distance from one another in accordance with another embodiment of the invention. [0059] FIG. 6 is a schematic side-view, partially in section, of an intravascular device having a first electrode on an expandable balloon, and a second electrode on a catheter shaft in accordance with another embodiment of the invention. [0060] FIG. 7 is a schematic side-view, partially in section, of an intravascular device having an expanding first electrode delivered through the lumen of a catheter and a complementary second electrode carried by the catheter in accordance with another embodiment of the invention. [0061] FIG. 8 is a schematic side-view, partially in section, of an intravascular device having an expandable basket and a plurality of electrodes at the basket in accordance with another embodiment of the invention. [0062] FIG. 9 is a schematic detail view of the apparatus of FIG. 8 illustrating one embodiment of the electrodes in accordance with another embodiment of the invention. [0063] FIG. 10 is a schematic side-view, partially in section, of an intravascular device having expandable ring electrodes for contacting the vessel wall and an optional insulation element in accordance with another embodiment of the invention. [0064] FIGS. 11A-11C are schematic detail views of embodiments of different windings for the ring electrodes of FIG. 10 . [0065] FIG. 12 is a schematic side-view, partially in section, of an intravascular device having ring electrodes of FIG. 10 with the windings shown in FIGS. 11A-11C . [0066] FIG. 13 is a schematic side-view, partially in section, of an intravascular device having a ring electrode and a luminally-delivered electrode in accordance with another embodiment of the invention. [0067] FIG. 14 is a schematic side-view, partially in section, of an intravascular device having a balloon catheter and expandable point contact electrodes arranged proximally and distally of the balloon in accordance with another embodiment of the invention. [0068] FIG. 15 is a schematic side-view of an intravascular device having a balloon catheter and electrodes arranged proximally and distally of the balloon in accordance with another embodiment of the invention. [0069] FIGS. 16A and 16B are schematic side-views, partially in section, illustrating stages of a method of using the apparatus of FIG. 15 in accordance with an embodiment of the invention. [0070] FIG. 17 is a schematic side-view of an intravascular device having a balloon catheter and a plurality of dynamically operable electrodes in accordance with another embodiment of the invention. [0071] FIG. 18 is a schematic side-view of an intravascular device having a distal electrode deployed through a lumen of the balloon catheter in accordance with another embodiment of the invention. [0072] FIGS. 19A and 19B are side-views, partially in section, illustrating methods of using the intravascular device shown in FIG. 18 to modulate renal neural activity in patients with various renal vasculatures. [0073] FIG. 20 is a side view, partially in section, illustrating an intravascular device having a plurality of electrodes arranged along the shaft of, and in line with, a centering element in accordance with another embodiment of the invention. [0074] FIG. 21 is a side-view, partially in section, illustrating an intravascular device having electrodes configured for dynamic radial repositioning to facilitate focusing of a pulsed electric field in accordance with another embodiment of the invention. [0075] FIG. 22 is a side-view, partially in section, of an intravascular device having an infusion/aspiration catheter in accordance with another embodiment of the invention. [0076] FIGS. 23A-23C are, respectively, a side-view, partially in section, and cross-sectional views along section line A-A of FIG. 23A , illustrating a method of using an intravascular device in accordance with an embodiment of the invention configured for passage of electrode(s) at least partially across the vessel wall. [0077] FIGS. 24A and 24B are side-views, partially in section, illustrating an intravascular device having detectors for measuring or monitoring treatment efficacy in accordance with another embodiment of the invention. DETAILED DESCRIPTION A. Overview [0078] The present invention relates to methods and apparatus for renal neuromodulation and/or other neuromodulation. More particularly, the present invention relates to methods and apparatus for renal neuromodulation using a pulsed electric field to effectuate electroporation or electrofusion. As used herein, electroporation and electropermeabilization are methods of manipulating the cell membrane or intracellular apparatus. For example, short high-energy pulses cause pores to open in cell membranes. The extent of porosity in the cell membrane (e.g., size and number of pores) and the duration of the pores (e.g., temporary or permanent) are a function of the field strength, pulse width, duty cycle, field orientation, cell type and other parameters. In general, pores will generally close spontaneously upon termination of lower strength fields or shorter pulse widths (herein defined as “reversible electroporation”). Each cell type has a critical threshold above which pores do not close such that pore formation is no longer reversible; this result is defined as “irreversible electroporation,” “irreversible breakdown” or “irreversible damage.” At this point, the cell membrane ruptures and/or irreversible chemical imbalances caused by the high porosity occur. Such high porosity can be the result of a single large hole and/or a plurality of smaller holes. Certain types of electroporation energy parameters also appropriate for use in renal neuromodulation are high voltage pulses with a duration in the sub-microsecond range (nanosecond pulsed electric fields, or nsPEF) which may leave the cellular membrane intact, but alter the intracellular apparatus or function of the cell in ways which cause cell death or disruption. Certain applications of nsPEF have been shown to cause cell death by inducing apoptosis, or programmed cell death, rather than acute cell death. Also, the term “comprising” is used throughout to mean including at least the recited feature such that any greater number of the same feature and/or additional types features are not precluded. [0079] Several embodiments of the present invention provide intravascular devices for inducing renal neuromodulation, such as a temporary change in target nerves that dissipates over time, continuous control over neural function, and/or denervation. The apparatus and methods described herein may utilize any suitable electrical signal or field parameters, e.g., any electric field, that will achieve the desired neuromodulation (e.g., electroporative effect). To better understand the structures of the intravascular devices and the methods of using these devices for neuromodulation, it is useful to understand the renal anatomy in humans. B. Selected Embodiments of Methods for Neuromodulation [0080] With reference now to FIG. 1 , the human renal anatomy includes kidneys K that are supplied with oxygenated blood by renal arteries RA, which are connected to the heart by the abdominal aorta AA. Deoxygenated blood flows from the kidneys to the heart via renal veins RV and the inferior vena cava IVC. FIG. 2 illustrates a portion of the renal anatomy in greater detail. More specifically, the renal anatomy also includes renal nerves RN extending longitudinally along the lengthwise dimension L of renal artery RA generally within the adventitia of the artery. The renal artery RA has smooth muscle cells SMC that surround the arterial circumference spiral around the angular axis θ of the artery, i.e., around the circumference of the artery. The smooth muscle cells of the renal artery accordingly have a lengthwise or longer dimension extending transverse (i.e., non-parallel) to the lengthwise dimension of the renal artery. The misalignment of the lengthwise dimensions of the renal nerves and the smooth muscle cells is defined as “cellular misalignment.” [0081] Referring to FIGS. 3A and 3B , the cellular misalignment of the renal nerves and the smooth muscle cells may be exploited to selectively affect renal nerve cells with reduced effect on smooth muscle cells. More specifically, because larger cells require less energy to exceed the irreversibility threshold of electroporation, several embodiments of electrodes of the present invention are configured to align at least a portion of an electric field generated by the electrodes with or near the longer dimensions of the cells to be affected. In specific embodiments, the intravascular device has electrodes configured to create an electrical field aligned with or near the lengthwise dimension of the renal artery RA to affect renal nerves RN. By aligning an electric field so that the field preferentially affects the lengthwise aspect of the cell rather than the diametric or radial aspect of the cell, lower field strengths may be used to necrose cells. As mentioned above, this is expected to reduce power consumption and mitigate effects on non-target cells in the electric field. [0082] Similarly, the lengthwise or longer dimensions of tissues overlying or underlying the target nerve are orthogonal or otherwise off-axis (e.g., transverse) with respect to the longer dimensions of the nerve cells. Thus, in addition to aligning the PEF with the lengthwise or longer dimensions of the target cells, the PEF may propagate along the lateral or shorter dimensions of the non-target cells (i.e. such that the PEF propagates at least partially out of alignment with non-target smooth muscle cells SMC). Therefore, as seen in FIGS. 3A and 3B , applying a PEF with propagation lines Li generally aligned with the longitudinal dimension L of the renal artery RA is expected to preferentially cause electroporation, electrofusion, denervation or other neuromodulation in cells of the target renal nerves RN without unduly affecting the non-target arterial smooth muscle cells SMC. The pulsed electric field may propagate in a single plane along the longitudinal axis of the renal artery, or may propagate in the longitudinal direction along any angular segment θ through a range of 0°-360°. [0083] Embodiments of the method shown in FIGS. 3A and 3B may have particular application with the intravascular methods and apparatus of the present invention. For instance, a PEF catheter placed within the renal artery may propagate an electric field having a longitudinal portion that is aligned to run with the longitudinal dimension of the artery in the region of the renal nerves RN and the smooth muscle cell SMC of the vessel wall so that the wall of the artery remains at least substantially intact while the outer nerve cells are destroyed. C. Embodiments of Systems and Additional Methods for Neuromodulation [0084] FIG. 4 shows one embodiment of an intravascular pulsed electric field apparatus 200 in accordance with the present invention that includes one or more electrodes configured to physically contact a target region within the renal vasculature and deliver a pulsed electric field across a wall of the vasculature. The apparatus 200 is shown within a patient's renal artery RA, but it can be positioned in other intravascular locations (e.g., the renal vein). This embodiment of the apparatus 200 comprises an intravascular catheter 210 having a proximal section 211 a , a distal section 211 b , and a plurality of distal electrodes 212 at the distal section 211 b . The proximal section 211 a generally has an electrical connector to couple the catheter 210 to a pulse generator, and the distal section 211 b in this embodiment has a helical configuration. The apparatus 200 is electrically coupled to a pulsed electric field generator 100 located proximal and external to the patient; the electrodes 212 are electrically coupled to the generator via catheter 210 . The generator 100 may be utilized with any embodiment of the present invention described hereinafter for delivery of a PEF with desired field parameters. It should be understood that electrodes of embodiments described hereinafter may be connected to the generator, even if the generator is not explicitly shown or described with each variation. [0085] The helical distal section 211 b of catheter 210 is configured to appose the vessel wall and bring electrodes 212 into close proximity to extra-vascular neural structures. The pitch of the helix can be varied to provide a longer treatment zone, or to minimize circumferential overlap of adjacent treatments zones in order to reduce a risk of stenosis formation. This pitch change can be achieved by combining a plurality of catheters of different pitches to form catheter 210 , or by adjusting the pitch of catheter 210 through the use of internal pull wires, adjusting mandrels inserted into the catheter, shaping sheaths placed over the catheter, or by any other suitable means for changing the pitch either in-situ or before introduction into the body. [0086] The electrodes 212 along the length of the pitch can be individual electrodes, a common but segmented electrode, or a common and continuous electrode. A common and continuous electrode may, for example, comprise a conductive coil formed into or placed over the helical portion of catheter 210 . A common but segmented electrode may, for example, be formed by providing a slotted tube fitted onto or into the helical portion of the catheter, or by electrically connecting a series of individual electrodes. [0087] Individual electrodes or groups of electrodes 212 may be configured to provide a bipolar signal, or all or a subset of the electrodes may be used together in conjunction with a separate external patient ground for monopolar use (the ground pad may, for example, be placed on the patient's leg). Electrodes 212 may be dynamically assignable to facilitate monopolar and/or bipolar energy delivery between any of the electrodes and/or between any of the electrodes and an external ground. [0088] Catheter 210 may be delivered to renal artery RA in a low profile delivery configuration within sheath 150 . Once positioned within the artery, the catheter may self-expand or may be expanded actively, e.g., via a pull wire or a balloon, into contact with an interior wall of the artery. A pulsed electric field then may be generated by the PEF generator 100 , transferred through catheter 210 to electrodes 212 , and delivered via the electrodes 212 across the wall of the artery. In many applications, the electrodes are arranged so that the pulsed electric field is aligned with the longitudinal dimension of the artery to modulate the neural activity along the renal nerves (e.g., denervation). This may be achieved, for example, via irreversible electroporation, electrofusion and/or inducement of apoptosis in the nerve cells. [0089] FIG. 5 illustrates an apparatus 220 for neural modulation in accordance with another embodiment of the invention. The apparatus 220 includes a pair of catheters 222 a and 222 b having expandable distal sections 223 a and 223 b with helical electrodes 224 a and 224 b , respectively. The helical electrodes 224 a and 224 b are spaced apart from each other by a desired distance within a patient's renal vasculature. Electrodes 224 a - b may be actuated in a bipolar fashion such that one electrode is an active electrode and the other is a return electrode. The distance between the electrodes may be altered as desired to change the field strength and/or the length of nerve segment modulated by the electrodes. The expandable helical electrodes may comprise shape-memory properties that facilitate self-expansion, e.g., after passage through sheath 150 , or the electrodes may be actively expanded into contact with the vessel wall, e.g., via an inflatable balloon or via pull wires, etc. The catheters 222 a - b preferably are electrically insulated in areas other than the distal helices of electrodes 224 a - b. [0090] FIG. 6 illustrates an apparatus 230 comprising a balloon catheter 232 having expandable balloon 234 , a helical electrode 236 arranged about the balloon 234 , and a shaft electrode 238 on the shaft of catheter 232 . The shaft electrode 238 can be located proximal of expandable balloon 234 as shown, or the shaft electrode 238 can be located distal of the expandable balloon 234 . [0091] When the apparatus 230 is delivered to a target vessel, e.g., within renal artery RA, the expandable balloon 234 and the helical electrode 236 are arranged in a low profile delivery configuration. As seen in FIG. 6 , once the apparatus has been positioned as desired, expandable balloon 234 may be inflated to drive the helical electrode 236 into physical contact with the wall of the vessel. In this embodiment, the shaft electrode 238 does not physically contact the vessel wall. [0092] It is well known in the art of both traditional thermal RF energy delivery and of relatively non-thermal pulsed RF energy delivery that energy may be conducted to tissue to be treated from a short distance away from the tissue itself. Thus, it may be appreciated that “nerve contact” comprises both physical contact of a system element with a nerve, as well as electrical contact alone without physical contact, or a combination of the two. A centering element optionally may be provided to place electrodes in a central region of the vessel. The centering element may comprise, for example, an expandable balloon, such as balloon 234 of apparatus 230 , or an expandable basket as described hereinafter. One or more electrodes may be positioned on a central shaft of the centering element—either longitudinally aligned with the element or positioned on one or both sides of the element—as is shaft electrode 238 of apparatus 230 . When utilizing a balloon catheter such as catheter 232 , the inflated balloon may act as an insulator of increased impedance for directing a pulsed electric field along a desired electric flow path. As will be apparent, alternative insulators may be utilized. [0093] As seen in FIG. 6 , when the helical electrode 236 physically contacts the wall of renal artery RA, the generator 100 may generate a PEF such that current passes between the helical electrode 236 and the shaft electrode 238 in a bipolar fashion. The PEF travels between the electrodes along lines Li that generally extend along the longitudinal dimension of the artery. The balloon 234 locally insulates and/or increases the impedance within the patient's vessel such that the PEF travels through the wall of the vessel between the helical and shaft electrodes. This focuses the energy to enhance denervation and/or other neuromodulation of the patient's renal nerves, e.g., via irreversible electroporation. [0094] FIG. 7 illustrates an apparatus 240 similar to those shown in FIGS. 4-6 in accordance with another embodiment of the invention. The apparatus 240 comprises a balloon catheter 242 having an expandable balloon 244 and a shaft electrode 246 located proximal of the expandable balloon 244 . The apparatus 240 further comprises an expandable helical electrode 248 configured for delivery through a guidewire lumen 243 of the catheter 242 . The helical electrode 248 shown in FIG. 7 is self-expanding. [0095] As seen in FIG. 7 , after positioning the catheter 242 in a target vessel (e.g. renal artery RA), the balloon 244 is inflated until it contacts the wall of the vessel to hold the shaft electrode 246 at a desired location within the vessel and to insulate or increase the impedance of the interior of the vessel. The balloon 244 is generally configured to also center the shaft electrode 246 within the vessel or otherwise space the shaft electrode apart from the vessel wall by a desired distance. After inflating the balloon 244 , the helical electrode 248 is pushed through lumen 243 until the helical electrode 248 extends beyond the catheter shaft; the electrode 248 then expands or otherwise moves into the helical configuration to physically contact the vessel wall. A bipolar pulsed electric field may then be delivered between the helical electrode 248 and the shaft electrode 246 along lines Li. For example, the helical electrode 248 may comprise the active electrode and the shaft electrode 246 may comprise the return electrode, or vice versa. [0096] With reference now to FIG. 8 , apparatus comprising an expandable basket having a plurality of electrodes that may be expanded into contact with the vessel wall is described. Apparatus 250 comprises catheter 252 having expandable distal basket 254 formed from a plurality of circumferential struts or members. A plurality of electrodes 256 are formed along the members of basket 254 . Each member of the basket illustratively comprises a bipolar electrode pair configured to contact a wall of renal artery RA or another desired blood vessel. [0097] Basket 254 may be fabricated, for example, from a plurality of shape-memory wires or ribbons, such as Nitinol, spring steel or elgiloy wires or ribbons, that form basket members 253 . When the basket members comprise ribbons, the ribbons may be moved such that a surface area contacting the vessel wall is increased. Basket members 253 are coupled to catheter 252 at proximal and distal connections 255 a and 255 b , respectively. In such a configuration, the basket may be collapsed for delivery within sheath 150 , and may self-expand into contact with the wall of the artery upon removal from the sheath. Proximal and/or distal connection 255 a and 255 b optionally may be configured to translate along the shaft of catheter 252 for a specified or unspecified distance in order to facilitate expansion and collapse of the basket. [0098] Basket 254 alternatively may be formed from a slotted and/or laser-cut hypotube. In such a configuration, catheter 252 may, for example, comprise inner and outer shafts that are moveable relative to one another. Distal connection 255 b of basket 254 may be coupled to the inner shaft and proximal connection 255 a of the basket may be coupled to the outer shaft. Basket 254 may be expanded from a collapsed delivery configuration to the deployed configuration of FIG. 8 by approximating the inner and outer shafts of catheter 252 , thereby approximating the proximal and distal connections 255 a and 255 b of the basket and expanding the basket. Likewise, the basket may be collapsed by separating the inner and outer shafts of the catheter. [0099] As seen in FIG. 9 , individual electrodes may be arranged along a basket strut or member 253 . In one embodiment, the strut is formed from a conductive material coated with a dielectric material, and the electrodes 256 may be formed by removing regions of the dielectric coating. The insulation optionally may be removed only along a radially outer surface of the member such that electrodes 256 remain insulated on their radially interior surfaces; it is expected that this will direct the current flow outward into the vessel wall. [0100] In addition, or as an alternative, to the fabrication technique of FIG. 9 , the electrodes may be affixed to the inside surface, outside surface or embedded within the struts or members of basket 254 . The electrodes placed along each strut or member may comprise individual electrodes, a common but segmented electrode, or a common and continuous electrode. Individual electrodes or groups of electrodes may be configured to provide a bipolar signal, or all or a subset of the electrodes may be actuated together in conjunction with an external patient ground for monopolar use. [0101] One advantage of having electrodes 256 contact the vessel wall as shown in the embodiment of FIG. 8 is that it may reduce the need for an insulating element, such as an expandable balloon, to achieve renal denervation or other neuromodulation. However, it should be understood that such an insulating element may be provided and, for example, expanded within the basket. Furthermore, having the electrodes contact the wall may provide improved field geometry, i.e., may provide an electric field more aligned with the longitudinal axis of the vessel. Such contacting electrodes also may facilitate stimulation of the renal nerves before, during or after neuromodulation to better position the catheter 252 before treatment or for monitoring the effectiveness of treatment. [0102] In a variation of apparatus 250 , electrodes 256 may be disposed along the central shaft of catheter 252 , and basket 254 may simply center the electrodes within the vessel to facilitate more precise delivery of energy across the vessel wall. This configuration may be well suited to precise targeting of vascular or extra-vascular tissue, such as the renal nerves surrounding the renal artery. Correctly sizing the basket or other centering element to the artery provides a known distance between the centered electrodes and the arterial wall that may be utilized to direct and/or focus the electric field as desired. This configuration may be utilized in high-intensity focused ultrasound or microwave applications, but also may be adapted for use with any other energy modality as desired. [0103] Referring now to FIG. 10 , it is expected that electrodes forming a circumferential contact with the wall of the renal artery may provide for more complete renal denervation or renal neuromodulation. In FIG. 10 , a variation of the present invention comprising ring electrodes is described. Apparatus 260 comprises catheter 262 having expandable ring electrodes 264 a and 264 b configured to contact the wall of the vessel. The electrodes may be attached to the shaft of catheter 262 via struts 266 , and catheter 262 may be configured for delivery to renal artery RA through sheath 150 in a low profile configuration. Struts 266 may be self-expanding or may be actively or mechanically expanded. Catheter 262 comprises guidewire lumen 263 for advancement over a guidewire. Catheter 262 also comprises optional inflatable balloon 268 that may act as an insulating element of increased impedance for preferentially directing current flow that is traveling between electrodes 264 a and 264 b across the wall of the artery. [0104] FIGS. 11A-11C illustrate various embodiments of windings for ring electrodes 264 . As shown, the ring electrodes may, for example, be wound in a coil ( FIG. 11A ), a zigzag ( FIG. 11B ) or a serpentine configuration ( FIG. 11C ). The periodicity of the winding may be specified, as desired. Furthermore, the type of winding, the periodicity, etc., may vary along the circumference of the electrodes. [0105] With reference to FIG. 12 , a variation of apparatus 260 is described comprising ring electrodes 264 a ′ and 264 b ′ having a sinusoidal winding in one embodiment of the serpentine winding shown in FIG. 11C . Struts 266 illustratively are attached to apexes of the sinusoid. The winding of electrodes 264 a ′ and 264 b ′ may provide for greater contact area along the vessel wall than do electrodes 264 a and 264 b , while still facilitating sheathing of apparatus 260 within sheath 150 for delivery and retrieval. [0106] FIG. 13 illustrates another variation of apparatus 260 comprising a proximal ring electrode 264 a , and further comprising a distal electrode 270 delivered through guidewire lumen 263 of catheter 262 . The distal electrode 270 is non-expanding and is centered within the vessel via catheter 262 . The distal electrode 270 may be a standard guide wire which is connected to the pulsed electric field generator and used as an electrode. However, it should be understood that electrode 270 alternatively may be configured for expansion into contact with the vessel wall, e.g., may comprise a ring or helical electrode. [0107] Delivering the distal electrode through the lumen of catheter 262 may reduce a delivery profile of apparatus 260 and/or may improve flexibility of the device. Furthermore, delivery of the distal electrode through the guidewire lumen may serve as a safety feature that ensures that the medical practitioner removes any guidewire disposed within lumen 263 prior to delivery of a PEF. It also allows for customization of treatment length, as well as for treatment in side branches, as described hereinafter. [0108] Ring electrodes 264 a and 264 b and 264 a ′ and 264 b ′ optionally may be electrically insulated along their radially inner surfaces, while their radially outer surfaces that contact the vessel wall are exposed. This may reduce a risk of thrombus formation and also may improve or enhance the directionality of the electric field along the longitudinal axis of the vessel. This also may facilitate a reduction of field voltage necessary to disrupt neural fibers. Materials utilized to at least partially insulate the ring electrodes may comprise, for example, PTFE, ePTFE, FEP, chronoprene, silicone, urethane, Pebax, etc. With reference to FIG. 14 , another variation of apparatus 260 is described, wherein the ring electrodes have been replaced with point electrodes 272 disposed at the ends of struts 266 . The point electrodes may be collapsed with struts 266 for delivery through sheath 150 and may self-expand with the struts into contact with the vessel wall. In FIG. 14 , catheter 262 illustratively comprises four point electrodes 272 on either side of balloon 268 . However, it should be understood that any desired number of struts and point electrodes may be provided around the circumference of catheter 262 . [0109] In FIG. 14 , apparatus 260 illustratively comprises four struts 266 and four point electrodes 272 on either side of balloon 268 . By utilizing all of the distally disposed electrodes 272 b as active electrodes and all proximal electrodes 272 a as return electrodes, or vice versa, lines Li along which the electric field propagates may be aligned with the longitudinal axis of a vessel. A degree of line Li overlap along the rotational axis of the vessel may be specified by specifying the angular placement and density of point electrodes 272 about the circumference of the catheter, as well as by specifying parameters of the PEF. [0110] With reference now to FIG. 15 , another variation of an intravascular PEF catheter is described. Apparatus 280 comprises catheter 282 having optional inflatable balloon or centering element 284 , shaft electrodes 286 a and 286 b disposed along the shaft of the catheter on either side of the balloon, as well as optional radiopaque markers 288 disposed along the shaft of the catheter, illustratively in line with the balloon. Balloon 284 serves as both a centering element for electrodes 286 and as an electrical insulator for directing the electric field, as described previously. [0111] Apparatus 280 may be particularly well-suited for achieving precise targeting of desired arterial or extra-arterial tissue, since properly sizing balloon 284 to the target artery sets a known distance between centered electrodes 286 and the arterial wall that may be utilized when specifying parameters of the PEF. Electrodes 286 alternatively may be attached to balloon 284 rather than to the central shaft of catheter 282 such that they contact the wall of the artery. In such a variation, the electrodes may be affixed to the inside surface, outside surface or embedded within the wall of the balloon. [0112] Electrodes 286 arranged along the length of catheter 282 can be individual electrodes, a common but segmented electrode, or a common and continuous electrode. Furthermore, electrodes 286 may be configured to provide a bipolar signal, or electrodes 286 may be used together or individually in conjunction with a separate patient ground for monopolar use. [0113] Referring now to FIGS. 16A and 16B , a method of using apparatus 280 to achieve renal denervation is described. As seen in FIG. 16A , catheter 282 may be disposed at a desired location within renal artery RA, balloon or centering element 284 may be expanded to center electrodes 286 a and 286 b and to optionally provide electrical insulation, and a PEF may be delivered, e.g., in a bipolar fashion between the proximal and distal electrodes 286 a and 286 b . It is expected that the PEF will achieve renal denervation and/or neuromodulation along treatment zone one T 1 . If it is desired to modulate neural activity in other parts of the renal artery, balloon 284 may be at least partially deflated, and the catheter may be positioned at a second desired treatment zone T 2 , as in FIG. 16B . The medical practitioner optionally may utilize fluoroscopic imaging of radiopaque markers 288 to orient catheter 282 at desired locations for treatment. For example, the medical practitioner may use the markers to ensure a region of overlap O between treatment zones T 1 and T 2 , as shown. [0114] With reference to FIG. 17 , a variation of apparatus 280 is described comprising a plurality of dynamically controllable electrodes 286 a and 286 b disposed on the proximal side of balloon 284 . In one variation, any one of proximal electrodes 286 a may be energized in a bipolar fashion with distal electrode 286 b to provide dynamic control of the longitudinal distance between the active and return electrodes. This alters the size and shape of the zone of treatment. In another variation, any subset of proximal electrodes 286 a may be energized together as the active or return electrodes of a bipolar electric field established between the proximal electrodes and distal electrode 286 b. [0115] Although the apparatus 280 shown in FIG. 17 has three proximal electrodes 286 a 1 , 286 a 2 and 286 a 3 , it should be understood that the apparatus 280 can have any alternative number of proximal electrodes. Furthermore, the apparatus 280 can have a plurality of distal electrodes 286 b in addition, or as an alternative, to multiple proximal electrodes. Additionally, one electrode of a pair may be coupled to the catheter 282 , and the other electrode may be delivered through a lumen of the catheter, e.g., through a guidewire lumen. The catheter and endoluminally-delivered electrode may be repositioned relative to one another to alter a separation distance between the electrodes. Such a variation also may facilitate treatment of a variety of renal vasculature anatomies. [0116] In the variations of apparatus 280 described thus far, distal electrode 286 b is coupled to the shaft of catheter 282 distal of balloon 284 . The distal electrode may utilize a lumen within catheter 282 , e.g., for routing of a lead wire that acts as ground. Additionally, the portion of catheter 282 distal of balloon 284 is long enough to accommodate the distal electrode. [0117] Catheters commonly are delivered over metallic and/or conductive guidewires. In many interventional therapies involving catheters, guidewires are not removed during treatment. As apparatus 280 is configured for delivery of a pulsed electric field, if the guidewire is not removed, there may be a risk of electric shock to anyone in contact with the guidewire during energy delivery. This risk may be reduced by using polymer-coated guidewires. [0118] With reference to FIG. 18 , another variation of apparatus 280 is described wherein distal electrode 286 b of FIGS. 16 and 17 has been replaced with a distal electrode 270 configured to be moved through a lumen of the catheter as described previously with respect to FIG. 13 . As will be apparent, proximal electrode 286 a alternatively may be replaced with the luminally-delivered electrode, such that electrodes 286 b and 270 form a bipolar electrode pair. Electrode 270 does not utilize an additional lumen within catheter 282 , which may reduce profile. Additionally, the length of the catheter distal of the balloon need not account for the length of the distal electrode, which may enhance flexibility. Furthermore, the guidewire must be exchanged for electrode 270 prior to treatment, which reduces a risk of inadvertent electrical shock. In one variation, electrode 270 optionally may be used as the guidewire over which catheter 282 is advanced into position prior to delivery of the PEF, thereby obviating a need for exchange of the guidewire for the electrode. Alternatively, a standard metallic guidewire may be used as the electrode 270 simply by connecting the standard guidewire to the pulsed electric field generator. The distal electrode 270 may be extended any desired distance beyond the distal end of catheter 282 . This may provide for dynamic alteration of the length of a treatment zone. Furthermore, this might facilitate treatment within distal vasculature of reduced diameter. [0119] With reference to FIGS. 19A and 19B , it might be desirable to perform treatments within one or more vascular branches that extend from a main vessel, for example, to perform treatments within the branches of the renal artery in the vicinity of the renal hilum. Furthermore, it might be desirable to perform treatments within abnormal or less common branchings of the renal vasculature, which are observed in a minority of patients. As seen in FIG. 19A , distal electrode 270 may be placed in such a branch of renal artery RA, while catheter 282 is positioned within the main branch of the artery. As seen in FIG. 19B , multiple distal electrodes 270 might be provided and placed in various common or uncommon branches of the renal artery, while the catheter remains in the main arterial branch. [0120] Referring to FIG. 20 , yet another variation of an intravascular PEF catheter is described. Apparatus 290 comprises catheter 292 having a plurality of shaft electrodes 294 disposed in line with centering element 296 . Centering element 296 illustratively comprises an expandable basket, such as previously described expandable basket 254 of FIG. 8 . However, it should be understood that the centering element alternatively may comprise a balloon or any other centering element. Electrodes 294 may be utilized in a bipolar or a monopolar fashion. [0121] Referring now to FIG. 21 , another variation of the invention is described comprising electrodes configured for dynamic radial repositioning of one or more of the electrodes relative to a vessel wall, thereby facilitating focusing of a pulsed electric field delivered by the electrodes. Apparatus 300 comprises catheter 302 having electrodes 304 disposed in line with nested expandable elements. The nested expandable elements comprise an inner expandable element 306 and an outer expandable centering element 308 . Electrodes 304 are disposed along the inner expandable element, while the outer expandable centering element is configured to center and stabilize catheter 302 within the vessel. Inner element 306 may be expanded to varying degrees, as desired by a medical practitioner, to dynamically alter the radial positions of electrodes 304 . This dynamic radial repositioning may be utilized to focus energy delivered by electrodes 304 such that it is delivered to target tissue. [0122] Nested elements 306 and 308 may comprise a balloon-in-balloon arrangement, a basket-in-basket arrangement, some combination of a balloon and a basket, or any other expandable nested structure. In FIG. 21 , inner expandable element 306 illustratively comprises an expandable basket, while outer expandable centering element 308 illustratively comprises an expandable balloon. Electrodes 302 are positioned along the surface of inner balloon 306 . [0123] Any of the variations of the present invention described herein optionally may be configured for infusion of agents into the treatment area before, during or after energy application, for example, to enhance or modify the neurodestructive or neuromodulatory effect of the energy, to protect or temporarily displace non-target cells, and/or to facilitate visualization. Additional applications for infused agents will be apparent. If desired, uptake of infused agents by cells may be enhanced via initiation of reversible electroporation in the cells in the presence of the infused agents. Infusion may be especially desirable when a balloon centering element is utilized. The infusate may comprise, for example, saline or heparinized saline, protective agents, such as Poloxamer-188, or anti-proliferative agents. Variations of the present invention additionally or alternatively may be configured for aspiration. For example, infusion ports or outlets may be provided on a catheter shaft adjacent a centering device, the centering device may be porous (for instance, a “weeping” balloon), or basket struts may be made of hollow hypotubes and slotted or perforated to allow infusion or aspiration. [0124] With reference to FIG. 22 , a variation of the present invention comprising an infusion/aspiration PEF catheter is described. Apparatus 310 comprises catheter 312 having proximal and distal inflatable balloons 314 a and 314 b , respectively. Proximal shaft electrode 316 a is disposed between the balloons along the shaft of catheter 312 , while distal electrode 316 b is disposed distal of the balloons along the catheter shaft. One or more infusion or aspiration holes 318 are disposed along the shaft of catheter 312 between the balloons in proximity to proximal electrode 316 a. [0125] Apparatus 310 may be used in a variety of ways. In a first method of use, catheter 312 is disposed within the target vessel, such as renal artery RA, at a desired location. One or both balloons 314 are inflated, and a protective agent or other infusate is infused through hole(s) 318 between the balloons in proximity to electrode 316 a . A PEF suitable for initiation of reversible electroporation is delivered across electrodes 316 to facilitate uptake of the infusate by non-target cells within the vessel wall. Delivery of the protective agent may be enhanced by first inflating distal balloon 314 b , then infusing the protective agent, which displaces blood, then inflating proximal balloon 314 a. [0126] Remaining infusate optionally may be aspirated such that it is unavailable during subsequent PEF application when irreversible electroporation of nerve cells is initiated. Aspiration may be achieved by at least partially deflating one balloon during aspiration. Alternatively, aspiration may be achieved with both balloons inflated, for example, by infusing saline in conjunction with the aspiration to flush out the vessel segment between the inflated balloons. Such blood flushing may reduce a risk of clot formation along proximal electrode 316 a during PEF application. Furthermore, flushing during energy application may cool the electrode and/or cells of the wall of the artery. Such cooling of the wall cells might protect the cells from irreversible electroporative damage, possibly reducing a need for infusion of a protective agent. [0127] After infusion and optional aspiration, a PEF suitable for initiation of irreversible electroporation in target nerve cells may be delivered across electrodes 316 to denervate or to modulate neural activity. In an alternative method, infusion of a protective agent may be performed during or after initiation of irreversible electroporation in order to protect non-target cells. The protective agent may, for example, plug or fill pores formed in the non-target cells via the irreversible electroporation. [0128] In another alternative method, a solution of chilled (i.e., less than body temperature) heparinized saline may be simultaneously infused and aspirated between the inflated balloons to flush the region between the balloons and decrease the sensitivity of vessel wall cells to electroporation. This is expected to further protect the cells during application of the PEF suitable for initiation of irreversible electroporation. Such flushing optionally may be continuous throughout application of the pulsed electric field. A thermocouple or other temperature sensor optionally may be positioned between the balloons such that a rate of chilled infusate infusion may be adjusted to maintain a desired temperature. The chilled infusate preferably does not cool the target tissue, e.g., the renal nerves. A protective agent, such as Poloxamer-188, optionally may be infused post-treatment as an added safety measure. [0129] Infusion alternatively may be achieved via a weeping balloon catheter. Further still, a cryoballoon catheter having at least one electrode may be utilized. The cryoballoon may be inflated within a vessel segment to locally reduce the temperature of the vessel segment, for example, to protect the segment and/or to induce thermal apoptosis of the vessel wall during delivery of an electric field. The electric field may, for example, comprise a PEF or a thermal, non-pulsed electric field, such as a thermal RF field. [0130] Referring now to FIGS. 23A , 23 B and 23 C, a variation of a PEF catheter configured for passage of electrode(s) at least partially across the vessel wall is described. For example, the electrode(s) may be positioned within the renal vein and then passed across the wall of the renal vein such that they are disposed in Gerota's or renal fascia and near or at least partially around the renal artery. In this manner, the electrode(s) may be positioned in close proximity to target renal nerve fibers prior to delivery of a pulsed electric field. [0131] As seen in FIG. 23A , apparatus 320 comprises catheter 322 having needle ports 324 and centering element 326 , illustratively an inflatable balloon. Catheter 322 also optionally may comprise radiopaque markers 328 . Needle ports 324 are configured for passage of needles 330 therethrough, while needles 330 are configured for passage of electrodes 340 . [0132] Renal vein RV runs parallel to renal artery RA. An imaging modality, such as intravascular ultrasound, may be used to identify the position of the renal artery relative to the renal vein. For example, intravascular ultrasound elements optionally may be integrated into catheter 322 . Catheter 322 may be positioned within renal vein RV using well-known percutaneous techniques, and centering element 326 may be expanded to stabilize the catheter within the vein. Needles 330 then may be passed through catheter 322 and out through needle ports 324 in a manner whereby the needles penetrate the wall of the renal vein and enter into Gerota's or renal fascia F. Radiopaque markers 328 may be visualized with fluoroscopy to properly orient needle ports 324 prior to deployment of needles 330 . [0133] Electrodes 340 are deployed through needles 330 to at least partially encircle renal artery RA, as in FIGS. 23A and 23B . Continued advancement of the electrodes may further encircle the artery, as in FIG. 23C . With the electrodes deployed, stimulation and/or PEF electroporation waveforms may be applied to denervate or modulate the renal nerves. Needles 330 optionally may be partially or completely retracted prior to treatment such that electrodes 340 encircle a greater portion of the renal artery. Additionally, a single electrode 340 may be provided and/or actuated in order to provide a monopolar PEF. [0134] Infusate optionally may be infused from needles 330 into fascia F to facilitate placement of electrodes 340 by creating a space for placement of the electrodes. The infusate may comprise, for example, fluids, heated or chilled fluids, air, CO 2 , saline, contrast agents, gels, conductive fluids or any other space-occupying material—be it gas, solid or liquid. Heparinized saline also may be injected. Saline or hypertonic saline may enhance conductivity between electrodes 340 . Additionally or alternatively, drugs and/or drug delivery elements may be infused or placed into the fascia through the needles. [0135] After treatment, electrodes 340 may be retracted within needles 330 , and needles 330 may be retracted within catheter 322 via needle ports 324 . Needles 330 preferably are small enough that minimal bleeding occurs and hemostasis is achieved fairly quickly. Balloon centering element 326 optionally may remain inflated for some time after retrieval of needles 330 in order to block blood flow and facilitate the clotting process. Alternatively, a balloon catheter may be advanced into the renal vein and inflated after removal of apparatus 320 . [0136] Referring to FIGS. 24A and 24B , variations of the invention comprising detectors or other elements for measuring or monitoring treatment efficacy are described. Variations of the invention may be configured to deliver stimulation electric fields, in addition to denervating or modulating PEFs. These stimulation fields may be utilized to properly position the apparatus for treatment and/or to monitor the effectiveness of treatment in modulating neural activity. This may be achieved by monitoring the responses of physiologic parameters known to be affected by stimulation of the renal nerves. Such parameters comprise, for example, renin levels, sodium levels, renal blood flow and blood pressure. Stimulation also may be used to challenge the denervation for monitoring of treatment efficacy: upon denervation of the renal nerves, the known physiologic responses to stimulation should no longer occur in response to such stimulation. [0137] Efferent nerve stimulation waveforms may, for example, comprise frequencies of about 1-10 Hz, while afferent nerve stimulation waveforms may, for example, comprise frequencies of up to about 50 Hz, Waveform amplitudes may, for example, range up to about 50V, while pulse durations may, for example, range up to about 20 milliseconds. When the nerve stimulation waveforms are delivered intravascularly, as in several embodiments of the present invention, field parameters such as frequency, amplitude and pulse duration may be modulated to facilitate passage of the waveforms through the wall of the vessel for delivery to target nerves. Furthermore, although exemplary parameters for stimulation waveforms have been described, it should be understood that any alternative parameters may be utilized as desired. [0138] The electrodes used to deliver PEFs in any of the previously described variations of the present invention also may be used to deliver stimulation waveforms to the renal vasculature. Alternatively, the variations may comprise independent electrodes configured for stimulation. As another alternative, a separate stimulation apparatus may be provided. [0139] One way to use stimulation to identify renal nerves is to stimulate the nerves such that renal blood flow is affected—or would be affected if the renal nerves had not been denervated or modulated. Stimulation acts to reduce renal blood flow, and this response may be attenuated or abolished with denervation. Thus, stimulation prior to neural modulation would be expected to reduce blood flow, while stimulation after neural modulation would not be expected to reduce blood flow to the same degree when utilizing similar stimulation parameters and location(s) as prior to neural modulation. This phenomenon may be utilized to quantify an extent of renal neuromodulation. Variations of the present invention may comprise elements for monitoring renal blood flow or for monitoring any of the other physiological parameters known to be affected by renal stimulation. [0140] In FIG. 24A , a variation of apparatus 280 of FIG. 16 is described having an element for monitoring of renal blood flow. Guidewire 350 having Doppler ultrasound sensor 352 has been advanced through the lumen of catheter 282 for monitoring blood flow within renal artery RA. Doppler ultrasound sensor 352 is configured to measure the velocity of flow through the artery. A flow rate then may be calculated according to the formula: [0000] Q=VA  (1) [0000] where Q equals flow rate, V equals flow velocity and A equals cross-sectional area. A baseline of renal blood flow may be determined via measurements from sensor 352 prior to delivery of a stimulation waveform, then stimulation may be delivered between electrodes 286 a and 286 b , preferably with balloon 284 deflated. Alteration of renal blood flow from the baseline, or lack thereof, may be monitored with sensor 352 to identify optimal locations for neuromodulation and/or denervation of the renal nerves. [0141] FIG. 24B illustrates a variation of the apparatus of FIG. 24A , wherein Doppler ultrasound sensor 352 is coupled to the shaft of catheter 282 . Sensor 352 illustratively is disposed proximal of balloon 284 , but it should be understood that the sensor alternatively may be disposed distal of the balloon. [0142] In addition or as an alternative to intravascular monitoring of renal blood flow via Doppler ultrasound, such monitoring optionally may be performed from external to the patient whereby renal blood flow is visualized through the skin (e.g., using an ultrasound transducer). In another variation, one or more intravascular pressure transducers may be used to sense local changes in pressure that may be indicative of renal blood flow. As yet another alternative, blood velocity may be determined, for example, via thermodilution by measuring the time lag for an intravascular temperature input to travel between points of known separation distance. [0143] For example, a thermocouple may be incorporated into, or provided in proximity to, each electrode 286 a and 286 b , and chilled (i.e., lower than body temperature) fluid or saline may be infused proximally of the thermocouple(s). A time lag for the temperature decrease to register between the thermocouple(s) may be used to quantify flow characteristic(s). A baseline estimate of the flow characteristic(s) of interest may be determined prior to stimulation of the renal nerves and may be compared with a second estimate of the characteristic(s) determined after stimulation. [0144] Commercially available devices optionally may be utilized to monitor treatment. Such devices include, for example, the SmartWire™, FloWire™ and WaveWire™ devices available from Volcano™ Therapeutics Inc., of Rancho Cordova, Calif., as well as the PressureWire® device available from RADI Medical Systems AB of Uppsala, Sweden. Additional commercially available devices will be apparent. An extent of electroporation additionally or alternatively may be monitored directly using Electrical Impedance Tomography (“EIT”) or other electrical impedance measurements, such as an electrical impedance index. [0145] Although preferred illustrative variations of the present invention are described above, it will be apparent to those skilled in the art that various changes and modifications may be made thereto without departing from the invention. For example, although the variations primarily have been described for use in combination with pulsed electric fields, it should be understood that any other electric field may be delivered as desired. It is intended in the appended claims to cover all such changes and modifications that fall within the true spirit and scope of the invention.

Methods and apparatus are provided for renal neuromodulation using a pulsed electric field to effectuate electroporation or electrofusion. It is expected that renal neuromodulation (e.g., denervation) may, among other things, reduce expansion of an acute myocardial infarction, reduce or prevent the onset of morphological changes that are affiliated with congestive heart failure, and/or be efficacious in the treatment of end stage renal disease. Embodiments of the present invention are configured for percutaneous intravascular delivery of pulsed electric fields to achieve such neuromodulation.

BACKGROUND Basic hashing works by computing a hash index I=H(K), I ε S I , where K ε S K is the key and H( ) is a hash function that maps elements of key space S K into a smaller index space S I . I is used to index a hash table, which may either store one or more keys which hash to the same index directly, or a pointer to the key storage. Hashing is frequently used as a mechanism to perform exact match searches of fixed- or variable-length keys. These searches may be performed to extract data from a results database that is associated with each stored key: e.g., Quality of Service (QoS) processing information for a packet flow which is defined by a key composed of certain packet header values. While hashing has good (O(1)) average search time, it has a worst case search time of O(N) for N keys, due to the possibility of hash collisions. FIG. 1 is a graph 100 illustrating the probability of hash collision P for a new key inserted into a hash table as a function of the table's load, defined as tile ratio of already inserted keys N to the number of bins B in the hash table. Here, simple uniform hashing is assumed, that being where any key will hash into any bin with equal probability. In FIG. 1 , the results are plotted for B ranging from 100 to 10000000, and it is observed that the resulting curve is insensitive to the absolute value of B. Note that P is approximately proportional to α for small values of α. The collision probability P at load α is equivalent to the expected fraction of occupied hash bins at that load. This is also equal to the expected fraction of keys that collide with another key at that load. Hash collisions can be resolved through a variety of mechanisms, including chaining, double hashing, open addressing, coalesced hashing, 2-choice hashing, and 2-left hashing. Disadvantageously, none of these mechanisms offer a deterministic search time for every key. An arbitrarily low ratio of colliding entries can only be achieved by operating at a low load; that is by making B large relative to N. However, this results in a waste of memory space. Exact match searches for fixed- or variable-length keys in databases is a common problem in computer science, especially in the context of packet forwarding e.g., Ethernet Media Access Control (MAC) lookup, and Internet Protocol (IP) 6-tuple flow lookup. Often in these applications, tens of millions or hundreds of millions of searches must be completed per second. In the context of packet forwarding, the database key might be anywhere from 16 to 48 bytes in size. Conventional solutions often involve sophisticated memory technology, such as the use of binary or ternary content addressable memory (CAMs), or combinations of well-known hashing techniques with memory technology, to retrieve those keys which are not conveniently resolved by the hashing technique. Conventional hash-based solutions cannot provide deterministic search time due to the need to resolve hash collisions, which in the worst case can be O(N) for N keys, whereas solutions which depend on sophisticated memory technology are typically expensive, have low density, and have high power consumption. The concept of using multiple hash tables is known in the art. For example, it is a basic component of the well-known 2-choice hashing and 2-left hashing methods. The method described in U.S. Pat. No. 5,920,900 to N. Poole, et al., while it uses multiple hash tables for collision resolution, does not bound every search to at most two hash table lookups. What is desired is a solution that provides deterministic search time, with bounded memory. SUMMARY The present invention relates to database access operations in computer systems. More particularly, and not by way of limitation, the present invention can be implemented in networking equipment, primarily in Ethernet switches and routers for wired networks which might be providing wireless traffic backhaul. Further, the present invention can be implemented in database search applications outside of networking equipment. In the context of forwarding in packet networks, fields in packet headers are used to access one or more databases which may store forwarding, QoS, security, and accounting context necessary to process and forward, or discard, the packet. A search key composed of one or more packet header fields is generated, and a database is searched using either exact (binary) match, longest prefix match, or ternary match methods. In an embodiment of the present invention, hash collisions in a base hash function are resolved in separate secondary hash tables. Further, if keys are inserted in the separate hash tables such that every key that collides in the base hash function is stored in the same secondary hash table, without collision with any other key stored in that table, then the identity of that table can be stored as a result of the base hash table search, bounding the maximum number of hash tables that need to be searched to two. The invention also considers the maximum amount of memory needed for the complete set of hash tables, as a function of the number of keys to store. The present invention is novel over multiple hash tables as it is adapted to store keys such that the base hash function lookup can be used to resolve the secondary hash table where a particular set of keys (those that collide at a particular value in the base hash function) are stored. BRIEF DESCRIPTION OF THE DRAWINGS In the following section, the invention will be described with reference to exemplary embodiments illustrated in the Figures, in which: FIG. 1 illustrates the probability of hash collision P for a new key inserted into a hash table as a function of the table's load: FIG. 2 is a data structure used in an embodiment of the present invention; FIG. 3 is a flow chart illustrating the steps of an embodiment of the present invention; and FIG. 4 is a flow chart illustrating the steps of searching for keys in an embodiment of the present invention: FIG. 5 is a flow chart illustrating the steps of inserting keys in an embodiment of the present invention; FIG. 6 is a flow chart illustrating the steps of deleting keys in an embodiment of the present invention; and FIG. 7 is a block diagram illustrating the components of an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION As seen in the graph 100 of FIG. 1 , values of α ˜ 0.69 or less, P≦0.5 that is at least half of the bins are empty and at least half of the keys do not collide. By removing the keys that collide with hash function H( ) and hashing them using a second function and table, it is possible to achieve a deterministic search time for all those keys which don't collide in H( ). This process can be repeated using additional independent hash functions and tables, until all keys are hashed without collision. Given N≦0.69×B 0 (α≦0.69), the number of hash functions and tables needed will converge to a value <<N as long as the number of unstored, i.e., colliding, keys at each stage j is no greater than 0.69×B j+1 , where B j is the size of the hash table at stage j. Since the number of collisions is less than or equal to half of the remaining keys at each stage, the subsequent hash tables can each be half the size of the previous one. Assuming that B 0 =2 M+1 , then I 0 can be represented in M bits, and M hash tables can be realized, each half the size of the other, such that the total memory utilized for hash tables is 2×B 0 =2 M+1 times the space needed for each individual hash bin (either a pointer or a matching key). Such a structure of hash tables should store at least 0.69×2 M keys without collision. In the worst-case, a database search for key K may require M independent hash searches. This worst-case can be reduced to a maximum of two hash searches using the method and system of the present invention. In the present inventions when inserting a new key into the search database, all keys that it may collide with in the base (first) hash function H 0 ( ) must be stored in the same hash table T j [ ], jε{0, M−1}, without collision. This allows the use a table_id field in each entry of the base hash table to indicate which of the M hash tables a particular search key may be stored in. Then a worst-case search would consist of computing the base hash function for key K. I 0 =H 0 (K), checking the table_id field value j in the base hash table at index I 0 , j⊂T 0 [I 0 ], computing the jth hash function I j =H j (K) (assuming j≠0), and comparing the key stored, directly or indirectly, at T j [I j ]. The present invention has two embodiments: one which minimizes memory storage, and another which minimizes search time. The embodiment of the present invention which minimizes memory storage uses the data structures 200 of FIG. 2 . The data strictures consist of three tables: an index_tbl 201 , a hash_tbl 202 , and a key_tbl 203 . The index_tbl 201 is of size B 0 =2 M , and each entry I stores a table_id value, which is used to indicate which of the AM hash tables the set of keys colliding in the base hash with value I are stored in. A special value of table_id (EMPTY) is reserved if there are no keys in the search database that hash to I in the base hash function, hash_tbl 202 is used to store the M hash tables, as pointers to the key storage in key_tbl 203 , hash_tbl 202 is of size 2×B 0 =2 M+1 : and each hash table is logically appended to the end of the previous one (at offset(T)=2×B 0 ×(1−2 −T ); e.g., offset(0)=0; offset(1)=B 0 ; offset(2)=1.5×B 0 : offset(3)=1.75×B 0 ). Each entry in hash_tbl 202 contains either NULL or a pointer to an entry in key_tbl 203 . Each key_tbl entry stores a key in the search database, a next pointer to another key_tbl entry, and a pointer to an entry in a results database, which stores the context information associated with the key_tbl entry. The next pointer is used to chain together all of the keys that collide in the base hash at a particular index, which is needed to facilitate insertions and deletions. When a key K does not collide with another key in the base hash, it is stored in the first hash table, i.e., in the top half of hash_tbl 202 ; otherwise it is stored in one of the secondary hash tables, i.e., in the bottom half of hash_tbl 202 . When K collides in the base hash function, the slot in hash_tbl 202 indexed by Ho(K) can be used to point to the key_tbl 203 entry which is the root of the linked list of key entries which collide with K in the base hash. FIG. 2 shows the use of three keys (K 0 ,K 1 ,K 2 ), where K 1 and K 2 collide in the base hash. K 0 is (logically) stored in the first hash table (indicated by the table_id=0 at index H 0 (K 0 ) of index_tbl). At the corresponding index in hash_tbl 202 there is a pointer to the entry in key_tbl 203 storing K 0 , K 1 and K 2 are (logically) stored in the second hash table. The second hash function H 1 ( ) is used to generate indices for hash_tbl 202 , whose corresponding entries point to the key storage for K 1 and K 2 . Those two key entries are linked in a list whose root can be reached via a pointer stored in hash_tbl 202 at index H 0 (K 1 )=H 0 (K 2 ), key_tbl 203 need be only of size N (the maximum number of keys supported). FIG. 3 is a flow chart 300 of the steps of an embodiment of the present invention, while FIGS. 4-6 are flow charts of the procedures for searching for, inserting, and deleting keys in an embodiment of the present invention. In FIG. 3 , a method of performing exact match searches using multiple hash tables is provided. Step 301 comprises the step of storing in the same hash table, all keys that it may collide with in the base (first) hash function H 0 ( ), when inserting a new key into the search database, using a table_id field in each entry of the base hash table to indicate which of the M hash tables a particular search key may be stored in. Step 302 comprises the step of computing the base hash function for key K. I 0 =H 0 (K). Step 303 is the step of checking the table_id field value j in the base hash table at index I 0 , j=T 0 [I 0 ]. Step 304 is the step of computing the jth hash function I j =H j (K)(assuming j≠0); and step 305 is the step of comparing the key stored (directly or indirectly) at T j [I j ]. FIG. 4 is a flow chart 400 illustrating the steps of searching for key K: 401 : Compute I 0 =H 0 (K). 402 : Fetch T=index_tbl[I 0 ]. 403 : If T=EMPTY, stop (K is not in the search database). 404 : Otherwise, compute I T =H T (K). 405 : Fetch P=hash_tbl[offset(T)+I T ] (shift I T into the correct hash table range in hash_tbl). 406 : Compare the key value stored in the key_tbl entry at address P to K. If they do not match, then K is not in the search database. If they do match, in step 407 , extract the results pointer. Note that searching is O(1) complexity. FIG. 5 is a flow chart 500 illustrating the steps of inserting key K: 501 : Search for key K, determining I 0 . 502 : If it is found, stop. 503 : Allocate an entry in key_tbl (at address P), set the key value to K, and set the results pointer appropriately. 504 : Fetch T=index_tbl[I 0 ]. 505 : If T=EMPTY, in step 506 , set index_tbl[I 0 ]=0. Otherwise, go to step 509 . 507 : Set hash_tbl[I 0 ]=P. 508 : Set the next pointer value in the key_tbl entry for K to NULL and stop. 509 : Otherwise (T≠EMPTY), compute I T =H T (K). 510 : Fetch Q=hash_tbl[offset(T)+I T ]. 511 : If Q=NULL, in step 512 , store P at hash_tbl[offset(T)+I T ] and at hash_tbl[I 0 ]. Otherwise, go to step 514 . 513 : Link the key_tbl entry for K to the tail of the linked list whose root is reached via hash_tbl[I 0 ] (if T>0), terminate the list, and stop. 514 : Otherwise (Q≠NULL), take the list of keys colliding with K in the base hash, find a new U>T where they each can be inserted without collision with other pre-existing keys, and move them there. 515 : Set index_tbl[I 0 ]=U. Return to step 513 : Link the key_tbl entry for K to the tail of the linked list whose root is reached via hash_tbl[I 0 ], terminate the list, and stop. Insertion complexity as described here is O(M). FIG. 6 is a flow chart 600 illustrating the steps of deleting key K: 601 : Search for key K, determining I 0 , T, I T , and P. 602 : Key found? If it is not found, stop. 603 : Delete the key entry stored in key_tbl at address P. If the entry is in the middle of a linked list of key entries, repair the list. 604 : If T>0, in step 605 , set hash_tbl[offset(T)+I T ]=NULL. Otherwise, go to step 608 . 606 : If hash_tbl[I 0 ]=P, in step 607 , change hash_tbl[I 0 ] to point to the first entry in the linked list in key_tbl previously storing key K and stop. If hash_tbl[I 0 ] does not=P, stop. 608 : If (T=0), set hash_tbl[I 0 ]=NULL. 609 : Set index_tbl[I 0 ]=EMPTY and stop. There may be cases of pathological keys, where, for a static set of hash functions H i ( ), iε{0, M−1}, the keys collide in every hash function, or there is no hash table that can be found where there is not a collision with at least one other key. In this event, one or more of the hash functions can be permuted (e.g., by changing the seed value for the hash function) and the keys that were stored in the corresponding hash table reinserted. This may increase the insertion time substantially. An embodiment of the method of the present invention which is optimized for search time would eliminate the need to perform step 405 of the search procedure by eliminating the separate hash_tbl, and extending key_tbl to size 2×B 0 . For large keys. e.g., larger than four bytes, this would typically result in an increase in memory usage as compared to the alternative embodiment. The method of the present invention described above was implemented using random 16-byte keys. The Fowler/Noll/Vo FNV-1a hash function was used with different seed values to realize each hash function. Two execution runs are shown in Tables 1 and 2, each with M=20, for α=0.69 (725000 keys) and α=0.90 (945000 keys)(α is relative to B 0 =2 M ). Table 1 shows the results of the former and Table 2 shows the results of the latter. Memory required for the first run was 23.937.184 bytes (assuming 16-byte keys) and for the second run, 28,337,184 bytes. The memory size difference was due to the greater size of key_tbl. As can be seen, the results for α=0.69 use fewer hash tables than what would have been expected from the discussion above. The results for α=0.90 show that there are only a few bins left in the unused hash tables ( 126 ). It was also observed that some executions for α=0.90 did not converge (without permuting the hash tables). TABLE 1 multi_hash execution for M = 20, α = 0.69 (725000 keys). Hash #keys α of hash Cumulative fraction of total keys table # bins stored table stored 0 1048576 362620 0.34 0.50 1 524288 222543 0.42 0.80 2 262144 92949 0.35 0.93 3 131072 34794 0.26 0.98 4 65536 10345 0.15 0.99 5 32768 1661 0.05 0.99 6 16384 88 0.01 0.99 7 8192 0 0 1.0 8 4096 0 0 1.0 9 2048 0 0 1.0 10 1024 0 0 1.0 11 512 0 0 1.0 12 256 0 0 1.0 13 128 0 0 1.0 14 64 0 0 1.0 15 32 0 0 1.0 16 16 0 0 1.0 17 8 0 0 1.0 18 4 0 0 1.0 19 2 0 0 1.0 TABLE 2 multi_hash execution for M = 20, α = 0.90 (945000 keys). Hash #keys α of hash Cumulative fraction of total keys table # bins stored table stored 0 1048576 384926 0.36 0.401 1 524288 289999 0.55 0.71 2 262144 139461 0.53 0.86 3 131072 67590 0.51 0.93 4 65536 33029 0.50 0.96 5 32768 15838 0.48 0.98 6 16384 7742 0.47 0.99 7 8192 3622 0.44 0.99 8 4096 1745 0.42 0.99 9 2048 759 0.37 0.99 10 1024 290 0.28 0.99 11 512 88 0.17 0.99 12 256 20 0.07 0.99 13 128 2 0.01 0.99 14 64 0 0 1.0 15 32 0 0 1.0 16 16 0 0 1.0 17 8 0 0 1.0 18 4 0 0 1.0 19 2 0 0 1.0 Referring now to FIG. 7 , a block diagram 700 illustrating the components of an embodiment of the present invention is presented. As seen therein, the present invention can be implemented using standard memory technology (e.g., DRAM). The search mechanism can be implemented either in software on a general purpose processor or network processor, or in computer hardware, such as a field programmable gate array (FPGA) or application specific integrated circuit (ASIC). The insertion and deletion mechanisms can be implemented in software on a general purpose processor. The total amount of memory required is on the order of twice the amount of memory needed to store the keys in the database (for 16 byte keys). Said system is adapted to perform exact match searches in deterministic time using multiple hash tables, and comprises means for storing in the same hash table, all keys that it may collide with in the base (first) hash function H 0 ( ), when inserting a new key into the search database, using a table_id field in each entry of the base hash table to indicate which of the M hash tables a particular search key may be stored in; means for computing the base hash function for key K, I 0 =H 0 (K); means for checking the table_id field value j in the base hash table at index I 0 , j=T 0 [I 0 ]; means for computing the jth hash function I j =H i (K)(assuming j≠0); and means for comparing the key stored (directly or indirectly) at T j [I j ]. The system of the present invention is further adapted to perform the above referenced steps of the method of the present invention. Advantages of the present invention over conventional methods and systems include the ability to search both fixed-length and variable-length search keys, whereas the conventional methods and systems assume fixed-length keys. Note that variable-length keys could be stored in a fixed-length field along with a key length. These conventional methods and systems assume a single hash function, which computes a hash value that must map 1:1 with the search key of equal length. Subsets of this hash value are used as indices into each of the multiple hash tables. Conventional methods and systems assume that the implementation stores information in each hash table entry to extract subsets of the hash value to be used to index a secondary or tertiary hash table for collision resolution, whereas the present invention uses a label in the index table (indexed by the base hash function) to indicate a separate hash function (which could be computed in parallel with the first hash function when implemented in hardware). Also, conventional methods and systems define a method which does not guarantee a maximum search time, whereas the present invention guarantees a maximum search time of two hash lookups. Finally, the conventional method and system is much less memory efficient than the present invention. As will be recognized by those skilled in the art, the innovative concepts described in the present application can be modified and varied over a wide range of applications. Accordingly, the scope of patented subject matter should not be limited to any of the specific exemplary teachings discussed above, but is instead defined by the following claims.

A method and system to perform exact match searches for fixed- or variable-length keys stored in a search database. The method is implemented using a plurality of hash tables, each indexed using an independent hash function. A system implementing this method provides deterministic search time, independent of the number of keys in the search database. The method permits two basic implementations; one which minimizes memory storage, and another which minimizes search time. The latter requires only two memory accesses to locate a key.

This application is a continuation of U.S. patent application Ser. No. 09/327,992, filed Jun. 8, 1999, now U.S. Pat. No. 6,148,152. FIELD OF THE INVENTION The field of this invention is a lens system and more specifically a lens system in a digital-imaging device. BACKGROUND OF THE INVENTION Digital cameras typically have two focusing methods available. One method is an auto focus mode and the other method is a manual focus mode where the user sets the distance for the object to be focused. The manual focus mode is used when the auto focus mode is incorrectly determining the correct focus for the object the user wishes to photograph. In the manual mode the user sets a distance and the camera typically moves the lens to a position that corresponds to the focus for that distance. FIG. 1 shows the distances used in the calculation to determine the proper lens location. Distance f is the focal length of the lens, distance s is the distance from the lens to the object to be focused, and distance s′ is the distance from the lens to the image of the object. In the manual focus mode the user sets the distance s and the camera calculates distance s′ using the formula 1/s′=1/f+1/s. Once distance s′ has been determined the camera will position the lens for the correct focus. The focal length of a lens is dependent on the focal length of each element in the lens and the spacing between the lens elements. The focal length of an individual lens element is dependent on the index of refraction of the material used for that lens element, the curvature of the two surfaces of the lens element and the thickness of the lens element. The index of refraction, the curvature of the surface and the thickness of the lens are dependent on the temperature of the lens element. The spacing of the lens elements is also dependent on the temperature of the lens system. This means that a change in temperature of the lens system will typically change the focal length for the lens system. When the temperature of the lens system in a digital camera changes without a corresponding change in the focal length used in the calculation to determine the correct lens position for a given object distance, the lens will not be positioned correctly for optimum focus. Scanners are digital imaging systems that have a constant distance between the object and the lens, and between the image and the lens. When there is a change in temperature in a scanner the focal length of the lens changes. Typically scanner lenses are fixed in place and can not be adjusted for the change in focal length. When the change in focal length is known, the image can be digitally adjusted to compensate for the change in focus. There is a need for a digital imaging system that can adjust for changes in temperature and determine optimum focus for a given object distance. SUMMARY OF THE INVENTION A system for thermal compensation of the optical performance of a lens system in a digital imaging device can improve the performance of the digital imaging system. The dark current from the photosensor is used to measure the temperature of the lens system. The digital processing system can use the temperature information to correct for aberrations in the lens system caused by changes in temperature. The focus function can use the temperature information to more accurately position the lens for optimum focus. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view block diagram of the distances for the object and image in a lens system. FIG. 2 is a side view block diagram of a lens. FIG. 3 is a side view block diagram showing defocus in a lens. FIG. 4 shows a block diagram of a system for temperature compensation in accordance with the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A system for thermal compensation of the optical performance of a lens system in a digital imaging device can improve the performance of the digital imaging system. Digital imaging systems such as digital cameras and scanners typically have a photosensor to convert the image of the object into electronic form. Typically the photosensors in digital cameras and scanners are charged coupled devices (CCD). Scanners have linear arrays of photosensors and digital cameras have area arrays of photosensors. The output of a CCD is made up of two components. The main component is a signal that is proportional to the intensity of light hitting each CCD element, integrated over a fixed time. There is also a leakage current component. The leakage current component is commonly known as dark current because the CCD produces the leakage current even in the absence of light. The dark current is the charge accumulated on the CCD during a fixed time, typically the same time that is used for the normal exposure. The dark current is dependent on the temperature of the CCD. Typically the dark current will double for every 7-8 degree C change in temperature. Once the dark current for a CCD at a given temperature is known, the present temperature of the CCD can be determined by a measurement of the dark current for that CCD. For example, when a CCD has a dark current of 10 milliamps at 25 degrees C, the temperature of the CCD when the dark current is 20 milliamps could be determined by the formula T e = 8  I c 2  I B + T B . Where T C is the present temperature, I C is the present dark current, I B is the known dark current at the given temperature T B . The temperature of the CCD is 33 degrees C when the dark current is 20 milliamps (33=((8*20)/(2*10))+25). The dark current can be measured in a digital camera by either having pixels on the CCD that are permanently covered by an opaque material or taking a measurement when the shutter is closed. The dark current can be measured in a scanner with pixels on the CCD that are permanently covered or by taking a measurement with the carriage under the top cover of the scanner. To determine the dark current at a known temperature the digital imaging system can be placed in a chamber at a known temperature or an auxiliary thermometer can be temporarily placed onto the system while a dark current measurement is done. This measured dark current at a known temperature is stored for later use. The focal length of a single lens is given by the equation 1 f = ( N - 1 )    [ 1 R 1 - 1 R 2 + t  ( N - 1 ) R 1  R 2  N ] (see FIG. 2 ). Where f is the focal length, R 1 is the radius of curvature of the first surface of the lens, R 2 is the radius of curvature of the second lens surface, t is the lens thickness, and N is the index of refraction of the lens material. Each of these components is dependent on temperature. The index of refraction for the material used is typically listed by wavelength with a correction factor ΔN/Δt for the change in refractive index with temperature that can be applied within a given temperature range. For example, BK7 is a common Schott Glass that has a temperature coefficient of refractive index of 2.8×10 −6 in the range between +20 and +40 degrees C. The lens thickness and radius of curvatures of the lens change with temperature depending of the coefficient of thermal expansion. The length at a new temperature is given by the formula NL=OL+OL*A*DT where NL is the new length, OL is the old length, A is the thermal coefficient of expansion for the lens material, and DT is the change in temperature. The thermal coefficient of expansion for lens materials is typically listed as a correction factor usable up to a limiting temperature. For example the thermal coefficient of expansion for BK7 is 7.1×10 −6 for temperatures up to 70 degrees C. The focal length of a lens system made up of two component lenses is given by the equation Fab = FaFb Fa + Fb - d . Where Fab is the focal length of the system, Fa is the focal length of single lens a, Fb is the focal length of single lens b, and d is the distance between the two lens elements. With a change in temperature, the focal lengths of each lens element can be recalculated and the distance between the elements can be determined by using the coefficient of thermal expansion of the material used to mount the two lens elements. Using these formulas the focal length of a lens system can be calculated for a range of temperatures. FIG. 4 shows a block diagram of a system for temperature compensation in a digital camera. The dark current from the photosensor array 402 is measured 404 and the processor 406 calculates and then positions the lens 408 for optimum focus. In the preferred embodiment of the invention the calculations for converting the dark current measurement into temperature are done external from the digital imaging system. For a digital camera the calculations for a range of dark current measurements are tabulated with the corresponding temperature equivalent. This calculation makes use of the measured dark current at a known temperature. The focal length for the lens is also calculated over a range of temperature values. And the correct lens position for optimum focus is calculated for a range of focal lengths. The focal length vs. temperature information, the dark current vs. temperature information, and the lens position vs. focal length information are combined to give a direct correlation between dark current vs. optimum focus position. This information, in tabular form, is installed into the digital camera and stored in nonvolatile memory and allows a simple lookup for the correct lens position given a measured dark current. By using the tabular form of this information the processor in the digital camera is freed from performing the computationally intensive calculations. In a scanner the lens is typically fixed in place. A change in temperature causing a change in focal length in the lens system can not be compensated for by adjusting the lens position. It is well know in the art that a known amount of defocus in a digital image can be corrected with digital image processing. Defocus is the difference between the actual distance between the image and the lens 302 and the distance between the image and the lens 304 at optimum focus (see FIG. 3 ). By measuring the dark current of the CCD the current temperature of the lens system with its corresponding focal length can be determined. Knowing the current focal length the amount of defocus for the system can be calculated. In the preferred embodiment, the computationally intensive calculation to determine the amount of defocus, given a measured dark current, is done external from the scanner. The dark current vs. defocus amount is in the scanner in a tabular form such that the processor looks up the defocus amount given a measured dark current. Once the defocus amount has been determined the defocus amount is used as an input to the digital focus compensation. For examples of digital image refocusing with a known defocus amount see The image processing handbook 2 nd ed., John C. Russ, CRC Press, Inc. 1995 (ISBN 0-8493-2516-1). The foregoing description of the present invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and other modifications and variations may be possible in light of the above teachings. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and various modifications as are suited to the particular use contemplated. It is intended that the appended claims be construed to include other alternative embodiments of the invention except insofar as limited by the prior art.

A system for thermal compensation of the optical performance of a lens system in a digital imaging device can improve the performance of the digital imaging system. The dark current from the photosensor is used to measure the temperature of the lens system. The digital processing system can use the temperature information to correct for aberrations in the lens system caused by changes in temperature. The focus function can use the temperature information to more accurately position the lens for optimum focus.

TECHNICAL FIELD [0001] The present invention relates to a base station, a terminal and a communication method. BACKGROUND ART [0002] “LTE-Advanced,” which is an evolved version of Long Term Evolution (LTE), is currently under study in 3GPP. In LTE-Advanced, a heterogeneous network (HetNet) is under study as a technique for improving the frequency utilization efficiency or the like. The heterogeneous network disposes a cell (small cell) which is a base station having low transmission power such as a pico cell or femt cell in a macro cell in addition to a cell arrangement centered on the macro cell which is a conventional base station having high transmission power. [0003] LTE-Advanced is proposing to separate, in a system constituting a heterogeneous network, a C-Plane (also referred to as “control plane”) from a U-Plane (also referred to as “data plane” or “user plane”) (hereinafter, referred to as “C/U separation”) (e.g., see Non-Patent Literature (hereinafter, simply referred to as “NPL”) 1). More specifically, during C/U separation, the macro cell performs movement management using the control plane to maintain connectivity and the small cell handles only the user plane using a wideband to thereby provide high throughput. [0004] Furthermore, when the user operating environment is taken into consideration, it is expected that small cells are more likely to be arranged indoors. On the other hand, macro cells are expected to maintain connectivity in a wide range under the control of control planes. Thus, indoors where a small cell is disposed, there can be a situation where while a terminal (which may also be referred to as “UE”) can receive a user plane favorably, the terminal cannot receive a control plane. That is, there can be a situation where although it is possible to perform communication using a user plane, it is possible neither to perform communication using a control plane nor to maintain connectivity. [0005] In contrast, NPL 1 discloses that both of a macro cell and a small cell include a control plane control section (RRC: radio resource control) and when it is not possible to maintain connectivity by the macro cell, the small cell transmits a control plane message to a terminal to thereby maintain connectivity. That is, the terminal continues communication even when it is outside a service area of the macro cell if it is located within the service area of the small cell and determines to be outside the communication range when links with both the macro cell and the small cell are outside the service areas. CITATION LIST Non-Patent Literature NPL 1 [0006] 3GPP TR 36.842 V12.0.0 (2013-12), Study on Small Cell enhancements for E-UTRA and E-UTRAN, Higher layer Aspects SUMMARY OF INVENTION Technical Problem [0007] However, in consideration of the fact that the small cell handles only a user plane as in the aforementioned case of C/U separation, it may be possible to introduce low-priced devices dedicated to data transmission/reception as a small cell. In this case, the small cell is not provided with any control plane control section that processes a control plane message as in the case of NPL 1. Thus, when it is not possible to perform communication using a control plane between the macro cell and the terminal during C/U separation, even if communication using a user plane between the small cell and the terminal is possible, the terminal cannot receive the control plane. [0008] Furthermore, when communication between the macro cell and the terminal using the control plane is not possible within the same radio system, traditional handover to the small cell may be performed to shift to communication without C/U separation. However, when the aforementioned small cell dedicated to data transmission/reception is introduced, handover to the small cell is not possible. [0009] In the future, it is expected that the macro cell and the small cell constituting different radio systems; for example, a macro cell may constitute an ESE-Advanced system and a small cell may constitute another system such as WiFi/WiGig. However, during C/U separation, when communication between macro cell and the terminal using a control plane is possible, handover processing becomes necessary between different radio systems, causing the processing to become complicated. [0010] Thus, when the terminal is located outside the service area of the macro cell during C/U separation, there is a problem that the processing for continuing data communication while continuing movement management becomes more difficult or more complicated. [0011] An object of the present invention is to provide a base station, a terminal and a communication method capable of continuing, even when a terminal is located outside the service area of a macro cell, movement management in the macro cell and continuing data communication in a small cell in a heterogeneous network in which a macro cell performs movement management using a control plane and a small cell handles a user plane. Solution to Problem [0012] A base station according to an aspect of the present invention is a base station in a macro cell that performs communication using a control plane in a communication system in which the macro cell performs communication using the control plane and a small cell performs communication using a user plane with respect to a terminal, the base station including: a first determining section that determines, when there is no response to data of the control plane transmitted to the terminal, that the terminal is located outside a service area of the base station; a transmitting and receiving section that transmits, when the first determining section determines that the terminal is located outside the service area of the base station, a confirmation packet that confirms connection between the terminal and the small cell as data of the user plane to the terminal via the small cell and receives a response to the confirmation packet as the data of the user plane from the terminal via the small cell; a second determining section that assumes, upon receiving the response, that the terminal is located inside the service area of the base station; and a control section that causes, when the second determining section assumes that the terminal is located inside the service area of the base station, the connection of the control plane between the terminal and the base station to continue. [0013] A terminal according to an aspect of the present invention is a terminal in a communication system in which a macro cell performs communication using a control plane and a small cell performs communication using a user plane with respect to the terminal, the terminal including: a first determining section that determines, when a reception level of a signal transmitted from the macro cell is less than a predetermined threshold, that the terminal is located outside a service area of the macro cell; a transmitting and receiving section that transmits, when the first determining section determines that the terminal is located outside the service area of the macro cell, a confirmation packet that confirms connection between the terminal and the small cell as data of the user plane to the macro cell via the small cell and receives a response to the confirmation packet as the data of the user plane from the macro cell via the small cell; a second determining section that assumes, upon receiving the response, that the terminal is located inside the service area of the macro cell; and a control section that causes, when the second determining section assumes that the terminal is located inside the service area of the macro cell, the connection of the control plane between the terminal and the macro cell to continue. [0014] A communication method according to an aspect of the present invention is a communication method in a base station in a macro cell that performs communication using a control plane in a communication system in which the macro cell performs communication using the control plane and a small cell performs communication using a user plane with respect to a terminal, the method including: a first determining step of determining, when there is no response to data of the control plane transmitted to the terminal, that the terminal is located outside a service area of the base station; a transmitting and receiving step of transmitting, when the first determining step determines that the terminal is located outside the service area of the base station, a confirmation packet that confirms connection between the terminal and the small cell as data of the user plane to the terminal via the small cell and receiving a response to the confirmation packet as the data of the user plane from the terminal via the small cell; a second determining step of assuming, upon receiving the response, that the terminal is located inside the service area of the base station; and a controlling step of causing, when the second determining section assumes that the terminal is located inside the service area of the base station, the connection of the control plane between the terminal and the base station to continue. [0015] A communication method according to an aspect of the present invention is a communication method in a terminal in a communication system in which a macro cell performs communication using a control plane and a small cell performs communication using a user plane with respect to the terminal, the method including: a first determining step of determining, when a reception level of a signal transmitted from the macro cell is less than a predetermined threshold, that the terminal is located outside a service area of the macro cell; a transmitting and receiving step of transmitting, when the first determining step determines that the terminal is located outside the service area of the base station, a confirmation packet that confirms connection between the terminal and the small cell as data of the user plane to the terminal via the small cell and receiving a response to the confirmation packet as the data of the user plane from the terminal via the small cell; a second determining step of assuming, upon receiving the response, that the terminal is located inside the service area of the macro cell; and a controlling step of causing, when the second determining step assumes that the terminal is located inside the service area of the macro cell, the connection of the control plane between the terminal and the macro cell to continue. Advantageous Effects of Invention [0016] According to the present invention, in a heterogeneous network in which a macro cell performs movement management using a control plane and a small cell handles a user plane, it is possible to continue, even when the terminal is located outside the service area of the macro cell, movement management in the macro cell and continue data communication in the small cell. BRIEF DESCRIPTION OF DRAWINGS [0017] FIG. 1 is a diagram illustrating a configuration example of a communication system according to Embodiment 1 of the present invention; [0018] FIG. 2 is a block diagram illustrating a configuration of a terminal according to Embodiment 1 of the present invention; [0019] FIG. 3 is a block diagram illustrating a configuration of a macro cell and a small cell according to Embodiment 1 of the present invention; [0020] FIG. 4 is a flowchart illustrating an operation of the terminal according to Embodiment 1 of the present invention; [0021] FIG. 5 is a flowchart illustrating an operation of the base station according to Embodiment 1 of the present invention; [0022] FIG. 6 is a sequence diagram illustrating an operation of the communication system according to Embodiment 1 of the present invention; [0023] FIG. 7 is a diagram illustrating protocol stacks of the macro cell and the small cell according to Embodiment 1 of the present invention; [0024] FIG. 8 is a block diagram illustrating a configuration of a terminal according to Embodiment 2 of the present invention; [0025] FIG. 9 is a block diagram illustrating a configuration of a macro cell and a small according to Embodiment 2 of the present invention; [0026] FIG. 10 is a flowchart illustrating an operation of the terminal according to Embodiment 2 of the present invention; [0027] FIG. 11 is a flowchart illustrating an operation of the base station according to Embodiment 2 of the present invention; [0028] FIG. 12 is a sequence diagram illustrating an operation of a communication system according to Embodiment 2 of the present invention; and [0029] FIG. 13 is a diagram illustrating protocol stacks of the macro cell, the small cell and the terminal according to Embodiment 2 of the present invention. DESCRIPTION OF EMBODIMENTS [0030] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Embodiment 1 [Overview of Communication System] [0031] A communication system according to the present embodiment includes, as shown in FIG. 1 , terminal 100 , base station 200 in a macro cell and base station 300 in a small cell. In the communication system, the macro cell controls a control plane (C-plane) to perform movement management and the small cell handles only a user plane (U-plane). That is, C/U separation is applied to the communication system shown in FIG. 1 , in which base station 200 performs communication with terminal 100 using the control plane and base station 300 performs communication using the user plane. [0032] A case will be described below where a radio system of the macro cell (base station 200 ) (hereinafter referred to as “first radio communication system”) is different from a radio system of the small cell (base station 300 ) (hereinafter referred to as “second radio communication system”). For example, the macro cell supports an LTE-Advanced system and the small cell supports a radio system such as WiFi/WiGig. Terminal 100 adopts a configuration communicable in both the radio system of the macro cell and the radio system of the small cell. [0033] Note that, the present embodiment is suitable for not only a case where the radio system of the macro cell is different from the radio system of the small cell in the communication system shown in FIG. 1 but also a case where the radio system of the macro cell is the same as the radio system of the small cell and the small cell is a base station that can communicate using only the user plane, for example. [Configuration of Terminal 100 ] [0034] FIG. 2 is a block diagram illustrating a configuration of terminal 100 according to the present embodiment. In FIG. 2 , terminal 100 includes receiving section 101 , transmitting section 102 , receiving-quality measuring section 103 , first determining section 104 , radio-resource control section 105 , second determining section 106 , keep-alive-packet transmitting/receiving section 107 , application section 108 , data processing section 109 , receiving section 110 , transmitting section 111 , receiving-quality measuring section 112 and data processing section 113 . [0035] In terminal 100 , receiving section 101 , receiving-quality measuring section 103 , data processing section 109 and transmitting section 102 constitute first-communication processing section 150 corresponding to a first radio system identical to that of the macro cell. On the other hand, receiving section 110 , receiving-quality measuring section 112 , data processing section 113 and transmitting section 111 constitute second-communication processing section 151 corresponding to a second radio system identical to that of the small cell (that is, different from the macro cell). [0036] Receiving section 101 demodulates a received signal received via an antenna and restores the signal. Examples of the received signal include a data signal and a reference signal transmitted from base station 200 (macro cell). During C/U separation, the received signal includes only control plane related data (control plane data). Receiving section 101 outputs the data signal or reference signal to receiving-quality measuring section 103 and data processing section 109 . [0037] Transmitting section 102 modulates a signal received from data processing section 109 and transmits the modulated signal via an antenna. For example, during C/U separation, the transmission signal includes only control plane data. [0038] Receiving-quality measuring section 103 measures receiving quality (e.g., reception level) of a signal transmitted from base station 200 using a reference signal received from receiving section 101 and outputs a receiving-quality measured value to first determining section 104 . Receiving-quality measuring section 103 may also measure an error rate (e.g., rate of occurrence of NG in CRC) of received data (restored information) as the receiving-quality measured value. [0039] First determining section 104 determines whether or not terminal 100 is located in a service area of the cell (e.g., base station 200 which is a macro cell) currently being measured based on the receiving-quality measured value received from receiving-quality measuring section 103 . For example, when the reception level of a signal transmitted from base station 200 is less than a predetermined threshold, first determining section 104 determines that terminal 100 is located outside the service area of base station 200 . First determining section 104 outputs the determination result (inside or outside the service area) to radio-resource control section 105 and second determining section 106 . [0040] Radio-resource control section 105 controls establishment of a connection of radio resources between terminal 100 and base station 200 (macro cell) or base station 300 (small cell) based on the control plane data received from data processing section 109 and the determination result received from first determining section 104 . Radio-resource control section 105 outputs the control plane data including control information on the connection establishment to data processing section 109 . For example, when the determination result from first determining section 104 shows that the terminal is located inside the service area, radio-resource control section 105 continues the connection with the cell as the determination target and cuts the connection with the determination target cell when the terminal is located outside the service area. [0041] During C/U separation, when the determination result on base station 200 (macro cell) received from first determining section 104 shows that the terminal is outside the service area, radio-resource control section 105 controls establishment of a connection of radio resources with the macro cell based on the determination result (re-determination result) received from second determining section 106 . More specifically, when the determination result received from second determining section 106 shows that the terminal is inside the service area, radio-resource control section 105 continues the connection with the macro cell (base station 200 ) and cuts the connection with the macro cell when the terminal is outside the service area. [0042] During C/U separation, second determining section 106 determines whether or not terminal 100 is located inside the service area of the small cell (base station 300 ) based on the receiving-quality measured value (receiving quality of signal transmitted from the small cell) received from receiving-quality measuring section 112 of second-communication processing section 151 . Furthermore, second determining section 106 receives the determination result (inside or outside the service area) on the macro cell from first determining section 104 . [0043] When terminal 100 is located outside the service area of the macro cell and terminal 100 is inside the service area of the small cell, second determining section 106 requests keep-alive-packet transmitting/receiving section 107 to transmit a keep-alive packet. Upon receiving a notice that a response (ACK) to the requested keep-alive packet has been received from keep-alive-packet transmitting/receiving section 107 , second determining section 106 determines that terminal 100 is inside the service area of the macro cell. On the other hand, upon receiving a notice that no response to the requested keep-alive packet has been received for a predetermined period from keep-alive-packet transmitting/receiving section 107 , second determining section 106 determines that terminal 100 is outside the service area of the macro cell. That is, upon receiving a response to the keep-alive packet, although second determining section 106 determines, based on the receiving quality, that terminal 100 is outside the service area of the macro cell, second determining section 106 assumes that terminal 100 is located inside the service area of the macro cell. Second determining section 106 outputs the determination result (re-determination result) to radio-resource control section 105 . [0044] Keep-alive-packet transmitting/receiving section 107 generates a keep-alive packet at the request from second determining section 106 and outputs the keep-alive packet to data processing section 109 . The keep-alive packet is a packet to confirm a connection between terminal 100 and the small cell, and is transmitted to the macro cell (base station 200 ) via the small cell (base station 300 ) as user plane-related data (user plane data). That is, when first determining section 104 determines that terminal 100 is located outside the service area of the macro cell, keep-alive-packet transmitting/receiving section 107 transmits a keep-alive packet that confirms the connection between terminal 100 and the small cell to the macro cell via the small cell as user plane data. While a response to the keep-alive packet is returned from base station 200 , keep-alive-packet transmitting/receiving section 107 may, for example, periodically transmit keep-alive packets. [0045] Keep-alive-packet transmitting/receiving section 107 receives a response (ACK) to the keep-alive packet transmitted to the macro cell from macro cell (base station 200 ) via the small cell (base station 300 ) as user plane data. Keep-alive-packet transmitting/receiving section 107 confirms whether or not a response (ACK) to the transmitted keep-alive packet is received and outputs the confirmation result (the presence or absence of a response) to second determining section 106 . [0046] Upon receiving the keep-alive packet transmitted from the macro cell from data processing section 109 , keep-alive-packet transmitting/receiving section 107 generates a response (ACK) to the keep-alive packet and outputs the response to the keep-alive packet to data processing section 109 . The response to the keep-alive packet is transmitted to the macro cell via the small cell as user plane data. [0047] Application section 108 processes normal application data (user plane data). Application section 108 processes a signal (keep-alive packet or response to the keep-alive packet) received from keep-alive-packet transmitting/receiving section 107 via data processing section 109 in the same way as normal application data and outputs the processed data (user plane data) to data processing section 109 . Application section 108 processes a signal (keep-alive packet or response to the keep-alive packet) received by data processing section 109 from the macro cell or the small cell in a manner similar to that of normal application data, and outputs the processed data to keep-alive-packet transmitting/receiving section 107 via data processing section 109 . [0048] Data processing section 109 outputs the control plane data out of the information received from receiving section 101 or data processing section 113 to radio-resource control section 105 and outputs the user plane data to application section 108 . Furthermore, data processing section 109 multiplexes the control plane data received from radio-resource control section 105 and the user plane data received from application section 108 and outputs the multiplexed signal to transmitting section 102 . [0049] During C/U separation, data processing section 109 outputs the user plane data received from application section 108 to data processing section 113 of second-communication processing section 151 and outputs the user plane data received from data processing section 113 to application section 108 . During C/U separation, data processing section 109 outputs the control plane data received from radio-resource control section 105 to transmitting section 102 and outputs the control plane data received from receiving section 101 to radio-resource control section 105 . [0050] Receiving section 110 demodulates a received signal received via an antenna and restores the signal. Examples of the received signal include a data signal and a reference signal transmitted from base station 300 (small cell). During C/U separation, the received signal includes only the user plane data. Receiving section 110 outputs the data signal or reference signal to receiving-quality measuring section 112 and data processing section 113 . [0051] Transmitting section 111 modulates a signal received from data processing section 113 and transmits the modulated signal via an antenna. For example, during C/U separation, the transmission signal includes only user plane data. [0052] As in the case of receiving-quality measuring section 103 , receiving-quality measuring section 112 measures receiving quality (e.g., reception level) of a signal transmitted from base station 300 using a reference signal received from receiving section 110 and outputs the receiving-quality measured value to second determining section 106 . [0053] Data processing section 113 outputs the signal received from receiving section 110 to data processing section 109 . Data processing section 113 outputs the signal received from data processing section 109 to transmitting section 111 . For example, during C/U separation, data processing section 113 outputs the user plane data received from data processing section 109 to transmitting section 111 and outputs the user plane data received from receiving section 110 to data processing section 109 . [Configurations of Base Station 200 and Base Station 300 ] [0054] FIG. 3 is a block diagram illustrating configurations of base station 200 (macro cell) and base station 300 (small cell) according to the present embodiment. For example, base station 200 supports a first radio system and base station 300 supports a second radio system. [Configuration of Macro Cell (Base Station 200 )] [0055] In FIG. 3 , base station 200 includes receiving section 201 , transmitting section 202 , data processing section 203 , radio-resource control section 204 , first determining section 205 , second determining section 206 , keep-alive-packet transmitting/receiving section 207 , application section 208 , inter-base-station I/F control section 209 . [0056] Receiving section 201 demodulates a received signal received via an antenna and restores the signal. For example, during C/U separation, the received signal includes only control plane data. Receiving section 201 outputs the restored signal to data processing section 203 . [0057] Transmitting section 202 modulates a signal received from data processing section 203 and transmits the modulated signal via an antenna. For example, during C/U separation, the transmission signal includes only control plane data. [0058] Data processing section 203 outputs control plane data out of information received from receiving section 201 or inter-base-station I/F control section 209 to radio-resource control section 204 and outputs user plane data to application section 208 . Data processing section 203 multiplexes the control plane data received from radio-resource control section 204 and the user plane data received from application section 208 and outputs the multiplexed signal to transmitting section 202 . [0059] During C/U separation, data processing section 203 transmits user plane data received from application section 208 to base station 300 via inter-base-station I/F control section 209 and outputs user plane data received from base station 300 via inter-base-station I/F control section 209 to application section 208 . During C/U separation, data processing section 203 outputs control plane data received from radio-resource control section 204 to transmitting section 202 and outputs control plane data received from receiving section 201 to radio-resource control section 204 . [0060] Radio-resource control section 204 generates signaling (control plane data) relating to control of radio resources and transmits the signaling to terminal 100 via data processing section 203 . Radio-resource control section 204 outputs the presence or absence of a response (ACK) to the signaling to first determining section 205 . [0061] Radio-resource control section 204 controls establishment of a connection of radio resources between terminal 100 and base station 200 based on the control plane data received from data processing section 203 and determination result (whether or not terminal 100 is located inside the service area of base station 200 ) received from first determining section 205 . Radio-resource control section 204 outputs control plane data including control information relating to connection establishment to data processing section 203 . More specifically, radio-resource control section 204 continues the connection between terminal 100 and base station 200 when the determination result from first determining section 205 shows that terminal 100 is located inside the service area and cuts the connection between terminal 100 and base station 200 when the determination result shows that terminal 100 is located outside the service area. [0062] During C/U separation, when the determination result on base station 200 (macro cell) received from first determining section 205 shows that terminal 100 is outside the service area, radio-resource control section 204 controls establishment of a connection of radio resources between terminal 100 and base station 200 based on the determination result (re-determination result) received from second determining section 206 . More specifically, when the determination result received from second determining section 206 shows that terminal 100 is inside the service area, radio-resource control section 204 continues the connection between terminal 100 and base station 200 , and cuts the connection between terminal 100 and base station 200 when the determination result shows that terminal 100 is outside the service area. [0063] First determining section 205 determines whether terminal 100 is inside or outside the service area of base station 200 using data about the presence or absence of a response to signaling (control plane data) received from radio-resource control section 204 . For example, when a period during which radio-resource control section 204 receives no response exceeds a predetermined period (upon expiration of the timer), first determining section 205 determines that terminal 100 is not in the service area of base station 200 (outside the service area). On the other hand, when radio-resource control section 204 receives a response within a predetermined period, first determining section 205 determines that terminal 100 is inside the service area of base station 200 . First determining section 205 outputs the determination result (inside or outside the service area) to radio-resource control section 204 and second determining section 206 . [0064] When the determination result on base station 200 received from first determining section 205 shows that terminal 100 is outside the service area, second determining section 206 requests keep-alive-packet transmitting/receiving section 207 to transmit a keep-alive packet. Upon receiving a notice that a response (ACK) to the requested keep-alive packet has been received from keep-alive-packet transmitting/receiving section 207 , second determining section 206 determines that terminal 100 is inside the service area of base station 200 . On the other hand, upon receiving a notice that no response to the requested keep-alive packet has been received for a predetermined period from keep-alive-packet transmitting/receiving section 207 , second determining section 206 determines that terminal 100 is outside the service area of base station 200 . That is, upon receiving a response to the keep-alive packet, although second determining section 206 determines, based on the presence or absence of a response to the control plane data, that terminal 100 is outside the service area of base station 200 , second determining section 206 assumes that terminal 100 is located inside the service area of base station 200 . Second determining section 206 outputs the determination result (re-determination result) to radio-resource control section 204 . [0065] At the request from second determining section 206 , keep-alive-packet transmitting/receiving section 207 generates a keep-alive packet and outputs the keep-alive packet to data processing section 203 . The keep-alive packet is transmitted to terminal 100 via the small cell (base station 300 ) as user plane data. That is, when first determining section 205 determines that terminal 100 is located outside the service area of base station 200 , keep-alive-packet transmitting/receiving section 207 transmits a keep-alive packet that confirms the connection between terminal 100 and the small cell to terminal 100 via the small cell as user plane data. For example, keep-alive-packet transmitting/receiving section 207 may periodically transmit keep-alive packets while a response to the keep-alive packet is returned from terminal 100 . [0066] Keep-alive-packet transmitting/receiving section 207 receives a response (ACK) to the keep-alive packet transmitted to terminal 100 from terminal 100 via the small cell (base station 300 ) as user plane data. Keep-alive-packet transmitting/receiving section 207 confirms whether or not a response (ACK) to the transmitted keep-alive packet is received and outputs the confirmation result (presence or absence of a response) to second determining section 206 . [0067] Upon receiving the keep-alive packet transmitted from terminal 100 from data processing section 203 , keep-alive-packet transmitting/receiving section 207 generates a response (ACK) to the keep-alive packet and outputs the response to data processing section 203 . The response to the keep-alive packet is transmitted to terminal 100 via the small cell as the user plane data. [0068] Application section 208 processes normal application data (user plane data). Application section 208 processes the signal (keep-alive packet or response to the keep-alive packet) received from keep-alive-packet transmitting/receiving section 207 via data processing section 203 in a manner similar to that of the normal application data and outputs the processed data to data processing section 203 . On the other hand, application section 208 processes the signal (keep-alive packet or response to the keep-alive packet) received by data processing section 203 from terminal 100 via the small cell in a manner similar to that of the normal application data and outputs the processed data to keep-alive-packet transmitting/receiving section 207 via data processing section 203 . [0069] Inter-base-station I/F control section 209 controls an interface that performs communication between base station 200 and base station 300 . For example, inter-base-station I/F control section 209 performs inter-base-station transfer using an IP (internet protocol) layer. [0070] Note that a case has been described in FIG. 2 and FIG. 3 where terminal 100 is provided with second determining section 106 and keep-alive-packet transmitting/receiving section 107 , and base station 200 (macro cell) is provided with second determining section 206 and keep-alive-packet transmitting/receiving section 207 . That is, in FIG. 2 and FIG. 3 , both terminal 100 and base station 200 have configurations capable of transmitting a keep-alive packet. However, in the present embodiment, only one of terminal 100 and base station 200 may transmit a keep-alive packet and the other may have a configuration or operation capable of transmitting only a response to the keep-alive packet. [Configuration of Base Station 300 (Small Cell)] [0071] In FIG. 3 , base station 300 includes receiving section 301 , transmitting section 302 , data processing section 303 and inter-base-station I/F control section 304 . [0072] Receiving section 301 demodulates a received signal received via an antenna and restores the signal. For example, during C/U separation, the received signal includes only user plane data transmitted from terminal 100 . Receiving section 301 outputs the restored signal to data processing section 303 . [0073] Transmitting section 302 modulates the signal received from data processing section 303 and transmits the modulated signal via an antenna. During C/U separation, the transmission signal includes only user plane data. [0074] Data processing section 303 transmits the signal received from receiving section 301 to base station 200 via inter-base-station I/F control section 304 . Data processing section 303 outputs a signal received from base station 200 to transmitting section 302 via inter-base-station I/F control section 304 . For example, during C/U separation, data processing section 303 outputs user plane data received from base station 200 to transmitting section 302 and outputs user plane data received from receiving section 301 to base station 200 . [0075] Inter-base-station I/F control section 304 controls the interface that performs communication between base station 300 and base station 200 . For example, inter-base-station I/F control section 304 performs inter-base-station transfer using an IP layer. [Operations of Terminal 100 and Base Station 200 ] [0076] Operations of terminal 100 and base station 200 having the above-described configurations will be described. [0077] FIG. 4 is a flowchart illustrating a processing flow when terminal 100 transmits a keep-alive packet and base station 200 returns a keep-alive packet. FIG. 5 is a flowchart illustrating a processing flow when base station 200 transmits a keep-alive packet and terminal 100 returns a response to the keep-alive packet. [0078] Note that terminal 100 and base station 200 may perform processes shown in FIG. 4 and FIG. 5 simultaneously or may perform only processes on one side. That is, only one of terminal 100 and base station 200 may transmit a keep-alive packet and the other may return a response to the keep-alive packet. [0079] First, a case shown in FIG. 4 where terminal 100 transmits a keep-alive packet will be described. [0080] In step (hereinafter simply denoted as “ST”) 101 , terminal 100 determines whether or not the reception level of a signal transmitted from base station 200 (macro cell) (e.g., receiving-quality measured value) satisfies a predetermined condition (reception level condition such as a predetermined threshold). When the reception level satisfies the predetermined condition (ST 101 : Yes, that is, when terminal 100 is inside the service area of base station 200 ), terminal 100 returns to the process in ST 101 . [0081] On the other hand, when the reception level does not satisfy the predetermined condition (ST 101 : No, that is, terminal 100 is outside the service area of base station 200 ), terminal 100 determines in ST 102 whether or not the communication mode with respect to terminal 100 is in a C/U separation state. For example, terminal 100 is notified in advance of whether C/U separation is applied or not through signaling of a higher layer. When a C/U separation state is in progress (ST 102 : Yes), terminal 100 proceeds to a process in ST 103 and when a C/U separation state is not in progress (ST 102 : No), terminal 100 proceeds to a process in ST 109 . [0082] In ST 103 , terminal 100 determines whether or not terminal 100 is located inside the service area of base station 300 (small cell) (whether or not terminal 100 satisfies the condition for terminal 100 to be located inside the service area of the small cell). For example, when the reception level (receiving-quality measured value) of a signal transmitted from base station 300 satisfies a predetermined threshold, terminal 100 determines that terminal 100 is located inside the service area of base station 300 . When terminal 100 is located inside the service area of the small cell (ST 103 : Yes), terminal 100 proceeds to a process in ST 104 and proceeds to a process in ST 109 when terminal 100 is not located inside the service area of the small cell (ST 103 : No). [0083] In ST 104 , terminal 100 stops communication (communication of control plane data) with base station 200 while maintaining the connection with base station 200 (macro cell). [0084] In ST 105 , terminal 100 transmits a keep-alive packet to base station 200 . Note that since direct communication is not possible between terminal 100 and base station 200 , terminal 100 transmits a keep-alive packet to base station 200 via base station 300 as user plane data. [0085] Upon receiving the keep-alive packet from terminal 100 in ST 105 , base station 200 returns a response (ACK) to the keep-alive packet to terminal 100 via base station 300 as user plane data. That is, when communication is possible between terminal 100 and base station 300 (small cell), ACK is returned from base station 200 to terminal 100 . [0086] In ST 106 , terminal 100 determines whether or not the response (ACK) to the keep-alive packet transmitted in ST 105 has been received within a predetermined period. When terminal 100 has received ACK (ST 106 : Yes), terminal 100 proceeds to a process in ST 107 and when terminal 100 has not received ACK (ST 106 : No), terminal 100 proceeds to a process in ST 109 . [0087] In ST 107 , terminal 100 determines to continue the connection state (connection) with base station 200 (macro cell). That is, although communication with base station 200 is actually stopped, if the response to the keep-alive packet is received in ST 106 , that is, communication between terminal 100 and base station 300 is possible, terminal 100 assumes that terminal 100 is located inside the service area of base station 200 and continues the connection with base station 200 . [0088] In ST 108 , terminal 100 determines whether the elapsed time of the timer that has started counting after the process in ST 107 exceeds a predetermined period or not (expiration of the timer or not). Upon expiration of the timer (ST 108 : Yes), terminal 100 returns to the process in ST 101 . That is, terminal 100 continues the connection with the macro cell until the timer expires (ST 108 : during “No”). [0089] When C/U separation is not applied (ST 102 : No) or when terminal 100 is outside the service areas of both the macro cell and the small cell (ST 103 : No or ST 106 : No), terminal 100 cuts communication with base station 200 in ST 109 and transitions to outside the service area of base station 200 (inside a service area of another cell). [0090] Next, a case shown in FIG. 5 where base station 200 transmits a keep-alive packet will be described. [0091] In ST 201 , base station 200 determines whether or not a response to control plane data (message) transmitted by base station 200 is received from terminal 100 . When a response is received (ST 201 : Yes, that is, terminal 100 is inside the service area of base station 200 ), base station 200 returns to the process in ST 201 . [0092] On the other hand, when no response is received (ST 201 : No, that is, terminal 100 is outside the service area of base station 200 ), base station 200 determines in ST 202 whether or not the communication mode with respect to terminal 100 is a C/U separation state. Base station 200 knows beforehand whether C/U separation is applicable to terminal 100 or not. Base station 200 proceeds to a process in ST 203 when the C/U separation state is in progress (ST 202 : Yes) and proceeds to a process in ST 208 when the C/U separation state is not in progress (ST 202 : No). [0093] In ST 203 , base station 200 stops communication (communication of control plane data) with terminal 100 while maintaining the connection state with terminal 100 . [0094] In ST 204 , base station 200 transmits a keep-alive packet to terminal 100 . Note that since direct communication between terminal 100 and base station 200 is not possible, base station 200 transmits a keep-alive packet to terminal 100 via base station 300 as user plane data. [0095] Upon receiving the keep-alive packet from base station 200 in ST 204 , terminal 100 returns a response (ACK) to the keep-alive packet to base station 200 via base station 300 as user plane data. That is, when communication between terminal 100 and base station 300 (small cell) is possible, ACK is returned from terminal 100 to base station 200 . [0096] In ST 205 , base station 200 determines Whether or not a response (ACK) to the keep-alive packet transmitted in ST 204 has been received within a predetermined period. Upon receiving ACK (ST 205 : Yes), base station 200 proceeds to a process in ST 206 and proceeds to a process in ST 208 upon receiving no ACK (ST 205 : No). [0097] In ST 206 , base station 200 determines to continue the connection state with terminal 100 . That is, although communication with terminal 100 is actually stopped, if a response to the keep-alive packet is received in ST 205 , that is, when communication between terminal 100 and base station 300 is possible, base station 200 assumes that terminal 100 is inside the service area of base station 200 and base station 200 continues the connection with terminal 100 . [0098] In ST 207 , base station 200 determines whether or not the elapsed time of the timer that has started counting after a process in ST 206 exceeds a predetermined period (expiration of the timer or not). Upon expiration of the timer (ST 207 : Yes), base station 200 returns to the process in ST 201 . That is, base station 200 continues the connection with terminal 100 until the timer expires (ST 207 : during “No”). [0099] When C/U separation is not applied (ST 202 : No) or when terminal 100 is outside the service areas of both the macro cell and the small cell (ST 205 : No), base station 200 cuts communication with terminal 100 in ST 208 and causes terminal 100 to transition to outside the service area of base station 200 (inside the service area of another cell). [0100] As described above, when terminal 100 is located outside the service area of the macro cell (base station 200 ), terminal 100 and/or base station 200 transmit(s) a keep-alive packet, as long as there is a response (ACK) to the keep-alive packet, base station 200 assumes that terminal 100 is located inside the service area of base station 200 and continues communication using a user plane while maintaining the connection of the control plane. When communication between terminal 100 and base station 200 becomes possible while continuing the connection of the control plane, terminal 100 and base station 200 resume communication of control plane data (C-Plane). [0101] Next, FIG. 6 is a sequence diagram illustrating exchange of signals among terminal 100 , base station 200 (macro cell) and base station 300 (small cell). [0102] In FIG. 6 , C/U separation is applied to terminal 100 , base station 200 performs communication using a control plane and base station 300 performs communication using a user plane. [0103] In ST 11 , base station 200 transmits a control plane message to terminal 100 . However, the control plane message does not reach terminal 100 in ST 11 . [0104] In this case, base station 200 cannot receive a response to the control plane message transmitted in ST 11 from terminal 100 . Thus, base station 200 determines that terminal 100 is located outside the service area of base station 200 . Terminal 100 determines that the reception level of the signal from base station 200 does not satisfy a predetermined condition. Here, suppose terminal 100 is located inside the service area of base station 300 . Thus, in ST 12 , terminal 100 detects that terminal 100 is located inside the service area of base station 300 and located outside the service area of base station 200 . [0105] In ST 13 and ST 14 , base station 200 and terminal 100 stop communication of the control plane while continuing communication of the user plane. [0106] In ST 15 , base station 200 transmits a keep-alive packet to terminal 100 via base station 300 . Upon receiving a keep-alive packet in ST 15 , terminal 100 transmits a response to the keep-alive packet to base station 200 via base station 300 in ST 16 . [0107] Note that the macro cell transmits a keep-alive packet in FIG. 6 as an example, but terminal 100 may also transmit a keep-alive packet and base station 200 may transmit a response to the keep-alive packet in ST 15 and ST 16 . [0108] Upon receiving the response to the keep-alive packet in ST 16 , base station 200 determines in ST 17 that communication is possible using the user plane between terminal 100 and base station 300 . In this case, although base station 200 cannot communicate with terminal 100 using the control plane, base station 200 maintains the connection using the control plane. Thus, even when terminal 100 is located outside the service area of base station 200 which is a macro cell, base station 200 continues movement management on terminal 100 , and base station 300 which is a small cell can continue data communication. [0109] While communication using the control plane between base station 200 and terminal 100 is stopped but the connection is continued, if it is detected that terminal 100 is located again inside the service area of base station 200 (ST 18 ), terminal 100 resumes communication using the control plane in ST 19 . [0110] FIG. 7 is a diagram provided for describing exchange of information using protocol stacks between base station 200 and base station 300 (small cell) while communication using the control plane between base station 200 (macro cell) and terminal 100 is stopped but the connection is continued. [0111] Note that in FIG. 7 , base station 200 applies, for example, an LTE-Advanced system. In this case, base station 200 includes, for the control plane, at least an RF (radio frequency) layer, a PHY (physical) layer, a MAC (medium access control) layer, an RLC (radio link control) layer, a PDCP (packet data control protocol) layer and an RRC (radio resource control) layer. Furthermore, base station 200 includes at least a PDCP layer for the user plane. The RF layer and the PHY layer correspond to layer 1 (L1), the MAC layer, the RLC layer and the PDCP layer correspond to layer 2 (L2) and the RRC layer corresponds to layer 3 (L3). For example, in base station 200 shown in FIG. 3 , receiving section 201 and transmitting section 202 correspond to layer 1, data processing section 203 corresponds to layer 2, and first determining section 205 and second determining section 206 correspond to layer 3. [0112] In FIG. 7 , base station 300 applies a WiGig system as a radio system different from base station 200 . In this case, base station 300 includes at least an RF layer, a PHY layer, a MAC layer, and an LLC (logical link control) layer for the user plane. For example, in base station 300 shown in FIG. 3 , receiving section 301 and transmitting section 302 correspond to the RF layer and PHY layer and data processing section 303 corresponds to the MAC layer and the LLC layer. Note that a case will be described in FIG. 7 where the small cell applies a radio system different from that of the macro cell, but the small cell is not limited to this, and the small cell may be a WiFi system or have a configuration in the same radio system as that of the macro cell in which only communication using a user plane can be implemented. [0113] In FIG. 7 , a core network (CN) is provided with MME/S-GW (mobility management entity/serving gateway). [0114] For example, when it is determined that terminal 100 is outside the service area of base station 200 , base station 200 generates a keep-alive packet in the IP layer and transmits the keep-alive packet generated using the user plane. Base station 200 receives a response to the keep-alive packet using the user plane. That is, terminal 100 and base station 200 exchange keep-alive packets via the small cell and using the user plane. Thus, when base station 200 can obtain a response to the keep-alive packet, it is determined that communication is possible between terminal 100 and base station 300 . [0115] At this time, as long as a response to the keep-alive packet is obtained, base station 200 continues the connection of the control plane. More specifically, as shown in FIG. 7 , although base station 200 stops communication using the control plane, base station 200 does not report to the core network (e.g., MME) that terminal 100 is outside the service area, but keeps the control plane “attached.” When communication between terminal 100 and base station 200 is made possible again by continuation of the connection of the control plane, terminal 100 and base station 200 are allowed to resume transmission/reception of control plane data without performing further connection processing. [0116] By this means, according to the present embodiment, when the terminal is outside the service area of the macro cell during C/U separation, the terminal and the macro cell transmit/receive a keep-alive packet using the user plane. When a response to the keep-alive packet is obtained, the terminal and the macro cell continue the connection of the control plane between the terminal and the macro cell. That is, as long as communication is possible between the terminal and the small cell using the user plane, it is possible to maintain the connection between the terminal and the macro cell even when communication between the terminal and the macro cell is not possible. [0117] Transmission/reception of a keep-alive packet between the terminal and the macro cell is performed using the user plane. Thus, even when the macro cell and the small cell are mutually different radio systems, the terminal and the macro cell can perform control to maintain the connection between the terminal and the macro cell using the user plane. Similarly, even when the macro cell and the small cell are the same radio system, and the small cell is provided with only a communication function using a user plane, the terminal and the macro cell can likewise perform control to maintain the connection between the terminal and the macro cell using the user plane. [0118] As described above, according to the present embodiment, in a heterogeneous network in which a macro cell performs movement management using a control plane and a small cell handles a user plane, even when the macro cell is located outside the service area, it is possible to continue data communication in the small cell while continuing movement management in the macro cell. Embodiment 2 [Configuration of Terminal 400 ] [0119] FIG. 8 is a block diagram illustrating a configuration of terminal 400 according to the present embodiment. Note that in FIG. 8 , components identical to those in Embodiment 1 ( FIG. 2 ) are assigned identical reference numerals and the description thereof will be omitted. [0120] In terminal 400 shown in FIG. 8 , when first determining section 104 determines that terminal 400 is outside the service area of a macro cell (base station 500 which will be described later) and that terminal 400 is inside the service area of a small cell (base station 300 ), second determining section 106 instructs C-Plane encapsulated packet transmitting/receiving section 401 to encapsulate control plane data. [0121] Upon receiving a notice that a response (ACK) to the encapsulated control plane data is received from C-Plane encapsulated packet transmitting/receiving section 401 , second determining section 106 re-determines that terminal 100 is inside the service area of the macro cell. On the other hand, upon receiving a notice that no response to the encapsulated control plane data is received for a predetermined period from C-Plane encapsulated packet transmitting/receiving section 401 , second determining section 106 re-determines that terminal 100 is outside the service area of the macro cell. That is, upon receiving a response to the encapsulated control plane data, second determining section 106 assumes, based on receiving quality, that terminal 400 is located inside the service area of the macro cell although terminal 400 is determined to be outside the service area of the macro cell. Second determining section 106 outputs the determination result (re-determination result) to radio-resource control section 105 . [0122] Upon receiving an instruction for encapsulation from second determining section 106 , C-Plane encapsulated packet transmitting/receiving section 401 receives control plane data from radio-resource control section 105 . C-Plane encapsulated packet transmitting/receiving section 401 encapsulates (tunneling) the received control plane data as an IP packet and outputs the encapsulated data to application section 108 . C-Plane encapsulated packet transmitting/receiving section 401 extracts control plane data from the IP packet (encapsulated data) received from application section 108 and outputs the control plane data to radio-resource control section 105 . Upon receiving a response (ACK) to the control plane data as the IP packet from application section 108 or upon receiving a response to the control plane data from radio-resource control section 105 , C-Plane encapsulated packet transmitting/receiving section 401 outputs a notice that a response to the control plane data is received to second determining section 106 . [0123] Thus, C-Plane encapsulated packet transmitting/receiving section 401 encapsulates the control plane data, transmits the encapsulated control plane data (IP packet) as a confirmation packet for confirming a connection between terminal 400 and the small cell and receives a response to the control plane data encapsulated in the macro cell. [0124] During C/U separation, when the determination result on base station 500 (macro cell) received from first determining section 104 shows that terminal 400 is outside the service area, radio-resource control section 105 controls establishment of a connection of radio resources with the macro cell based on the determination result (re-determination result) received from second determining section 106 . More specifically, radio-resource control section 105 continues the connection with the macro cell (base station 500 ) when the determination result received from second determining section 106 shows that terminal 400 is inside the service area and disconnects the connection with the macro cell when the determination result shows that terminal 400 is outside the service area. [0125] During the continuation of the connection with the macro cell (base station 500 ), radio-resource control section 105 outputs control plane data directed to base station 500 to C-Plane encapsulated packet transmitting/receiving section 401 and receives control plane data from base station 500 from C-Plane encapsulated packet transmitting/receiving section 401 based on the determination result of second determining section 106 . [0126] Application section 108 outputs the encapsulated data received from C-Plane encapsulated packet transmitting/receiving section 401 to data processing section 109 as user plane data. Furthermore, upon receiving user plane data including the encapsulated data from data processing section 109 , application section 108 outputs the data to C-Plane encapsulated packet transmitting/receiving section 401 . [Configuration of Macro Cell (Base Station 500 )] [0127] FIG. 9 is a block diagram illustrating a configuration of base station 500 according to the present embodiment. Note that in FIG. 9 , components identical to those in Embodiment 1 ( FIG. 3 ) are assigned identical reference numerals and the description thereof will be omitted. [0128] In base station 500 shown in FIG. 9 , when first determining section 205 determines that terminal 400 is not located in the service area of base station 500 , second determining section 206 instructs C-Plane encapsulated packet transmitting/receiving section 501 to encapsulate control plane data. [0129] Upon receiving a notice that a response (ACK) to the encapsulated control plane data is received from C-Plane encapsulated packet transmitting/receiving section 501 , second determining section 206 re-determines that terminal 100 is located in the service area (inside the service area) of base station 200 . On the other hand, upon receiving a notice that no response to the encapsulated control plane data is received for a predetermined period from C-Plane encapsulated packet transmitting/receiving section 501 , second determining section 206 re-determines that terminal 100 is not located in the service area (outside the service area) of base station 200 . That is, upon receiving a response to the encapsulated control plane data, although it is determined, based on receiving quality, that terminal 400 is outside the service area of base station 500 , second determining section 206 assumes that terminal 400 is located inside the service area of base station 500 . Second determining section 206 outputs the determination result (re-determination result) to radio-resource control section 204 . [0130] Upon receiving an instruction for encapsulation from second determining section 206 , C-Plane encapsulated packet transmitting/receiving section 501 receives the control plane data from radio-resource control section 204 . C-Plane encapsulated packet transmitting/receiving section 501 encapsulates the received control plane data as an IP packet and outputs the encapsulated data to application section 208 . C-Plane encapsulated packet transmitting/receiving section 501 extracts the control plane data from the IP packet (encapsulated data) received from application section 108 and outputs the control plane data to radio-resource control section 204 . Upon receiving a response (ACK) to the control plane data from application section 208 as an IP packet, or upon receiving a response to the control plane data from radio-resource control section 204 , C-Plane encapsulated packet transmitting/receiving section 501 outputs a notice of such receipt of the response to the control plane data to second determining section 206 . [0131] Thus, C-Plane encapsulated packet transmitting/receiving section 501 encapsulates the control plane data, transmits the encapsulated control plane data (IP packet) as a confirmation packet for confirming a connection between terminal 400 and the small cell and receives a response to the control plane data encapsulated by terminal 400 . [0132] During C/U separation, when the determination result on base station 500 (macro cell) received from first determining section 205 shows that terminal 400 is outside the service area, radio-resource control section 204 controls establishment of a connection of radio resources between terminal 400 and base station 500 based on the determination result (re-determination result) received from second determining section 206 . More specifically, when the determination result received from second determining section 206 shows that terminal 400 is inside the service area, radio-resource control section 204 continues the connection between terminal 400 and base station 500 , and disconnects the connection between terminal 400 and base station 500 when the determination result shows that terminal 400 is outside the service area. [0133] While the connection between terminal 400 and base station 500 is continued based on the determination result of second determining section 206 , radio-resource control section 204 outputs control plane data directed to terminal 400 to C-Plane encapsulated packet transmitting/receiving section 501 and receives control plane data from terminal 400 from C-Plane encapsulated packet transmitting/receiving section 501 . [0134] Application section 208 outputs the encapsulated data received from C-Plane encapsulated packet transmitting/receiving section 501 as user plane data to data processing section 203 . Upon receiving the user plane data including the encapsulated data from data processing section 203 , application section 208 outputs the data to C-Plane encapsulated packet transmitting/receiving section 501 . [Operations of Terminal 400 and Base Station 500 ] [0135] Operations of terminal 400 and base station 500 having the above-described configurations will be described. [0136] FIG. 10 is a flowchart illustrating a processing flow when terminal 400 encapsulates and transmits control plane data (C-Plane message). FIG. 11 is a flowchart illustrating a processing flow when base station 500 encapsulates and transmits control plane data. [0137] Note that in FIG. 10 and FIG. 11 , processes identical to those in Embodiment 1 ( FIG. 4 , FIG. 5 ) are assigned identical reference numerals and the description thereof will be omitted. [0138] First, a case will be described where terminal 400 shown in FIG. 10 encapsulates and transmits control plane data. [0139] In FIG. 10 , in ST 301 , terminal 400 encapsulates control plane data and transmits the encapsulated data to base station 500 via base station 300 (small cell) as user plane data. Upon receiving the encapsulated control plane data from terminal 400 in ST 301 , base station 500 encapsulates a response (ACK) to the control plane data and returns the encapsulated response to terminal 400 via base station 300 as user plane data. [0140] In ST 302 , terminal 400 determines whether or not terminal 400 has received a response (ACK) to the control plane data transmitted in ST 301 within a predetermined period. When terminal 400 has received ACK (ST 302 : Yes), terminal 400 proceeds to a process in ST 107 and proceeds to a process in ST 109 when terminal 400 has not received ACK (ST 302 : No). [0141] Next, a case will be described where base station 500 shown in FIG. 11 encapsulates and transmits control plane data. [0142] In FIG. 11 , in ST 401 , base station 500 encapsulates control plane data and transmits the encapsulated data to terminal 400 via base station 300 as user plane data. Upon receiving the control plane data encapsulated in ST 401 from base station 500 , terminal 400 encapsulates a response (ACK) to the control plane data and returns the encapsulated response to base station 500 via base station 300 as user plane data. [0143] In ST 402 , base station 500 determines whether or not base station 500 has received a response (ACK) to the keep-alive packet transmitted in ST 401 within a predetermined period. Base station 500 proceeds to a process in ST 206 when base station 500 has received ACK (ST 401 : Yes) and proceeds to a process in ST 208 when base station 500 has not received ACK (ST 401 : No). [0144] As described above, when terminal 400 is located outside the service area of the macro cell (base station 500 ), terminal 400 and/or base station 500 encapsulate(s) and transmit(s) control plane data, assume(s), as long as there is a response (ACK) to the control plane data, that terminal 400 is located inside the service area of base station 500 and continue(s) communication using a user plane while maintaining the connection of the control plane. During the continuation of the connection of the control plane, if communication between terminal 400 and base station 500 is made possible, terminal 400 and base station 500 resume communication of control plane data (C-Plane). [0145] Next, FIG. 12 is a sequence diagram illustrating exchange of signals among terminal 400 , base station 500 (macro cell) and base station 300 (small cell). Note that in FIG. 12 , processes identical to those in Embodiment 1 ( FIG. 6 ) are assigned identical reference numerals and the description thereof will be omitted. [0146] In FIG. 12 , C/U separation is applied to terminal 400 as in the case of FIG. 6 and base station 500 performs communication using a control plane and base station 300 performs communication using a user plane. [0147] In FIG. 12 , in ST 21 , base station 500 encapsulates control plane data (control plane message) and transmits the encapsulated control plane data to terminal 400 via base station 300 . When terminal 400 has received the encapsulated control plane data in ST 21 , terminal 400 transmits a response to the control plane data to base station 500 via base station 300 in ST 22 . Note that although FIG. 12 shows a case where the macro cell transmits control plane data as an example, terminal 400 may also transmit the encapsulated control plane data and base station 500 may transmit a response to the control plane data. [0148] Thus, even when terminal 400 is located outside the service area of base station 500 which is a macro cell, base station 500 transmits/receives encapsulated control plane data using the user plane, and base station 500 can thereby continue movement management on terminal 400 , and base station 300 which is a small cell can continue data communication. [0149] As described above, FIG. 13 is a diagram provided for describing exchange of information using protocol stacks among terminal 400 , base station 500 (macro cell) and base station 300 (small cell) while communication using the control plane between base station 500 (macro cell) and terminal 400 is stopped but the connection is still continued. [0150] Note that in FIG. 13 , as in the case of FIG. 7 , base station 500 applies, for example, an LTE-Advanced system, and base station 300 applies a WiGig radio system as a radio system different from that of base station 200 . As shown in FIG. 13 , terminal 400 has functions of both the LTE-Advanced system and the WiGig system. More specifically, terminal 400 has at least an RF layer, a PHY layer, a MAC layer, an RLC layer, a PDCP layer, an RRC layer, and an NAS (non access stratum) layer for the control plane of the LIE-Advanced system. Moreover, terminal 400 has at least an RF layer, a PHY layer, a MAC layer and an LLC layer for the user plane of the WiGig radio system. [0151] For example, when it is determined that terminal 400 is outside the service area of base station 500 , base station 500 encapsulates the control plane data (RRC message) as an IP layer packet and transmits the generated control plane data using the user plane. Base station 500 receives a response to the encapsulated control plane data using the user plane. That is, terminal 400 and base station 500 exchange the control plane data and its response via the small cell using the user plane. Thus, when base station 500 can obtain a response to the control plane data transmitted/received using the user plane, it is determined that communication is possible between terminal 400 and base station 300 . [0152] At this time, as long as a response to the encapsulated control plane data is obtained, base station 500 continues the connection of the control plane. More specifically, as shown in FIG. 13 , although base station 500 stops communication of the control plane data using the control plane, base station 500 keeps the control plane “attached” without notifying the core network (e.g., MME) that terminal 400 is outside the service area. Since the connection of the control plane is continued, if communication between terminal 400 and base station 500 is made possible again, terminal 400 and base station 500 can resume transmission/reception of control plane data using the control plane without performing further connection processing. [0153] By this means, according to the present embodiment, during C/U separation, when the terminal is located outside the service area of the macro cell, the terminal and the macro cell transmit/receive the encapsulated control plane data using the user plane. When a response to the control plane data transmitted/received using the user plane is obtained, the terminal and the macro cell continue the connection of the control plane between the terminal and the macro cell. That is, when communication of the user plane between the terminal and the small cell is possible, it is possible to maintain the connection between the terminal and the macro cell even when communication between the terminal and the macro cell is not possible. [0154] Even when direct communication between the terminal and the small cell is not possible, the control plane data is transmitted/received using the user plane. Thus, even when the macro cell and the small cell are different radio systems, the macro cell can communicate the control plane data using the user plane and can execute movement management uninterruptedly. Similarly, even when the macro cell and the small cell are the same radio system and the small cell is provided with only the communication function of the user plane, the macro cell can communicate the control plane data using the user plane and can thereby execute movement management uninterruptedly. [0155] Thus, according to the present embodiment, as in the case of Embodiment 1, in the heterogeneous network in which the macro cell executes movement management using the control plane and the small cell handles the user plane, it is possible to continue data communication in the small cell while continuing movement management in the macro cell even when the terminal is located outside the service area of the macro cell. Furthermore, according to the present embodiment, even when direct communication between the terminal and the macro cell is not possible, it is possible for the macro cell to appropriately perform movement management compared to Embodiment 1. [0156] The embodiments of the present invention have been described so far. [0157] Note that although cases have been described with the above embodiments as examples where the present invention is configured by hardware, the present invention can also be realized by software in cooperation with hardware. [0158] Each function block employed in the description of each of the aforementioned embodiments may typically be implemented as an LSI constituted by an integrated circuit. These may be individual chips or partially or totally contained on a single chip. “LSI” is adopted here but this may also be referred to as “IC,” “system LSI,” “super LSI,” or “ultra LSI” depending on differing extents of integration. [0159] Further, the method of circuit integration is not limited to LSI's, and implementation using dedicated circuitry or general purpose processors is also possible. After LSI manufacture, utilization of a programmable FPGA (field programmable gate array) or a reconfigurable processor where connections and settings of circuit cells within an LSI can be reconfigured is also possible. [0160] Further, if integrated circuit technology comes out to replace LSI's as a result of the advancement of semiconductor technology or a derivative other technology, it is naturally also possible to carry out function block integration using this technology. Application of biotechnology is also possible. [0161] The disclosure of Japanese Patent Application No. 2014-058089 filed on Mar. 20, 2014, the contents of Which including the specification and drawings are incorporated herein by reference in its entirety. INDUSTRIAL APPLICABILITY [0162] The present invention is suitable for use in mobile communication systems. REFERENCE SIGNS LIST [0000] 100 Terminal 200 , 300 Base station 101 , 110 , 201 , 301 Receiving section 102 , 111 , 202 , 302 Transmitting section 103 , 112 Receiving-quality measuring section 104 , 205 First determining section 105 , 204 Radio-resource control section 106 , 206 Second determining section 107 , 207 Keep-alive-packet transmitting/receiving section 108 , 208 Application section 109 , 113 , 203 , 303 Data processing section 150 First-communication processing section 151 Second-communication processing section 209 , 304 Inter-base-station I/F control section

Even when a terminal goes out of a macro cell, data communication in the small cell can be caused to continue while the mobile management in a macro cell is continued. When a first determination unit ( 205 ) determines that a terminal exists outside the cell of a base station ( 200 ), an existence recognition packet transmission/reception unit ( 207 ) transmits a recognition packet, which is used for recognition, to the terminal via a small cell, and thereafter receives a response to the recognition packet from the terminal via the small cell. When a second determination unit ( 206 ) determines, because of the reception of the response, that the terminal exits inside the cell of the base station ( 200 ), a radio resource control unit ( 204 ) causes the connection of the control plane between the terminal and the base station ( 200 ) to continue.

TECHNICAL FIELD [0001] This invention relates to inputting Chinese characters. BACKGROUND [0002] Chinese characters are represented by logograms that are not necessarily associated with the pronunciation of the characters. In order to input a Chinese character into a digital device such as a computer or cell phone, each Chinese character is mapped to one or more input keystrokes. There are two types of methods of mapping Chinese characters to input keystrokes. One method is based on sound. The pronunciation of the Chinese character is phonetically represented using the English alphabet. Each Chinese character is mapped to its phonetic representation in English. A requirement for using a sound-based method is that the user must know how the Chinese character is pronounced. [0003] The second type of Chinese character input method is based on shape. Each Chinese character is composed of one or more shape elements. In a shaped-based input method, the shape elements are mapped to keystrokes. Each Chinese character is represented by one or more keystrokes that are mapped to one or more shape elements. Using a combination of shape elements in a specified sequence identifies a Chinese character. SUMMARY [0004] In one aspect, the disclosure features a method for use in causing Chinese characters that comprise shape elements to be constructed by an electronic device. A user is enabled to enter any of a set of Chinese characters sufficient to enable typical communication to a Chinese reader. The method comprises associating groups of shape elements with respective non-numerically associated touch locations of the electronic device, and upon receipt of an indication that one or more of the touch locations have been invoked, constructing a Chinese character based on the shape elements associated with the invoked touch locations. The shape elements are a complete set of shape elements from which all Chinese characters in the set are formed. Every one of the shape elements belongs to one of the groups. All shape elements in each group resemble each other in shape. [0005] In another aspect, the disclosure features a device that comprises a processor, memory coupled to the processor, and non-numerically associated touch locations. The memory stores a complete set of shape elements from which all Chinese characters in a set of Chinese characters that are sufficient to enable typical communication to a Chinese reader. The shape elements are organized in groups that are associated with respective non-numerically associated touch locations of the device. Every one of the shape elements belongs to one of the groups. All shape elements in each group resemble each other in shape. The processor is configured to upon receipt of an indication that one or more of the touch locations have been invoked, construct a Chinese character based on the shape elements of the database that are associated with the invoked touch locations. The constructed Chinese character is any of the set of Chinese characters sufficient to enable typical communication to a Chinese reader. [0006] In another aspect, the disclosure features a computer program product tangibly stored on a computer readable storage device. The computer program product comprises instructions for causing a processor to: upon receipt of an indication that one or more of non-numerically associate touch locations have been invoked, access a database that stores a complete set of shape elements from which all Chinese characters in a set of Chinese characters that are sufficient to enable typical communication to a Chinese reader, and construct a Chinese character based on the shape elements of the database that are associated with the invoked touch locations. The shape elements are organized in groups that are associated with the respective non-numerical touch locations. Every one of the shape elements belongs to one of the groups. All shape elements in each group resemble each other in shape. The constructed Chinese character is any of the set of Chinese characters sufficient to enable typical communication to a Chinese reader. [0007] Embodiments of the method, the device, and the computer program product may also include one or more of the following features. Each touch location is displayed to the user with a label having a shape, and wherein the shape of the label resembles at least some of the shape elements of a group of shape elements that is associated with the touch location. The labels of the touch locations comprise Roman letters or selected shape elements of the associated groups. The touch locations are part of a virtual key set. The touch locations are part of a physical keyboard. A Chinese character is constructed by requiring the user to invoke no more than three touch locations in a predetermined order. The no more than three touch locations are associated with no more than three shape elements, respectively, and the predetermined order corresponds to a sequence of writing the three shape elements in the Chinese character under standard rules of Chinese character writing. The no more than three shape elements comprise a first shape element that is written first in the Chinese character under the standard rules. The no more than three shape elements also comprise a second shape element that is written immediately after the first shape element in the Chinese character under the standard rules. The no more than three shape elements also comprise a third shape element that is written the last in the Chinese character under the standard rules. A Chinese character is constructed by constructing the Chinese character as a part of constructing a Chinese phrase containing two or more Chinese characters. The Chinese phrase comprises a first Chinese character and a second Chinese character after the first Chinese character. The Chinese phrase is constructed by requiring the user to invoke touch locations in a predetermined order that comprises a first shape element to be written first in the first Chinese character, a second shape element to be written immediately after the first shape element in the first Chinese character, a first shape element to be written first in the second Chinese character, and a second shape element to be written immediately after the first shape element in the second Chinese character. The Chinese phrase consists of two Chinese characters and the user is required to invoke no more than four touch locations. The Chinese phrase consists of three Chinese characters and the user is required to invoke no more than five touch locations. The Chinese phrase consists of four Chinese characters and the user is required to invoke no more than six touch locations. Multiple Chinese characters are constructed based on the indication that one or more of the touch locations are invoked, and the user is enabled to choose a desired Chinese character as input among the multiple Chinese characters. The touch locations can be virtual locations on a touch screen or physical keys of a keyboard. The database can be updated with additional Chinese characters or phrases in association with sequences of touch locations. DESCRIPTION OF DRAWINGS [0008] FIGS. 1A , 1 C, 1 D, and 1 E are examples of Chinese characters. [0009] FIG. 1B shows a shape element of the Chinese character of FIG. 1A . [0010] FIG. 2 is a block diagram showing an example of a device that implements the methods of the disclosure. [0011] FIG. 3 shows an example of grouping of shape elements. [0012] FIG. 4 shows an example of association of the grouped shape elements of FIG. 3 with keys of a QWERTY keyboard. [0013] FIGS. 5A and 5B are schematic diagrams showing examples of user interfaces and keyboards for inputting Chinese characters or phrases. [0014] FIGS. 6A and 6B are schematic diagrams showing examples of user interfaces on a touch screen for inputting Chinese characters or phrases. [0015] FIGS. 7 and 8 are flow diagrams showing examples of processes performed by devices implementing the methods of this disclosure. [0016] FIG. 9 is a schematic diagram showing an example of a user interface for a dictionary application. [0017] FIG. 10 shows an example of a two-character Chinese phrase. [0018] FIG. 11 is a block diagram showing an example of a computer system. DETAILED DESCRIPTION [0019] Chinese characters can be entered into a digital device intuitively and parsimoniously without requiring long-time learning or memorization. For example, Chinese characters are decomposed into shape elements that are grouped into families based on the similarity of the shapes, making it easy for the user to remember which elements are in the grouping. Each grouping is assigned to a particular input keystroke, which can be an actual physical key on a keyboard, or a virtual button on a touchscreen. This can make the entry method highly flexible to accommodate a number of different hardware configurations. If the groupings are assigned to keys in a physical keyboard, the key is chosen so that the key identifier (e.g., the Roman letter or English letter) resembles the shape elements to make it more intuitive for the user and facilitates recall of which keystroke represents a particular grouping. On a virtual keyboard (which is available on touch screen devices such as mobile phones, tablets, and computers), each virtual key may be labeled with one or more representative elements of an associated grouping so that the user does not have to memorize the association and can select keystrokes for the shape elements by looking at the label of the key. The labels of the key can be shape elements of the groupings or other elements that succinctly convey the underlying shape element assignments by virtue of shape similarity for the user to readily identify the key for the groupings. [0020] Chinese characters can be efficiently entered one character at a time, in two-character phrases, in three-character phrases, and in four-character phrases using a series of keystrokes containing a limited number of, e.g., less than four, keystrokes. Each series of keystrokes can identify a Chinese character or a phrase without much redundancy. In other words, for most of the Chinese characters and phrases, the series of the keystrokes is unique (while many Chinese characters and phrases can have the same pronunciation). The user entering the unique keystroke series can input the Chinese characters quickly without needing to select the desired Chinese characters from groups of redundant candidates. [0021] Referring to FIG. 1A and 1B , an example of a Chinese character is illustrated. The Chinese character 100 is decomposed into shape elements 101 , 102 , 103 , 104 , 105 . Each shape element 101 , 102 , 103 , 104 , 105 is formed of a sequence of strokes. For example, as shown in FIG. 1B , the shape element 101 contains strokes 150 (an abbreviated “dot” stroke), 151 (horizontal to the right), 152 (downward to the right), 153 (downward to the left), 154 (horizontal to the right). In writing, generally, the strokes (e.g., the strokes 150 - 154 ) of each shape element (e.g., the shape element 101 ) and the shape elements are written in a particular order, e.g., from top to down and from left to right, to complete a Chinese character. In the example of the Chinese character 100 , one starts writing from a top left corner 120 (i.e., the shape element 101 ), moves down along a direction 121 (i.e., the shape element 102 ), and then moves along the right direction 122 and starts with from the top right corner 125 (i.e., the shape element 103 and then the shape element 104 ). Within each shape element 101 , 102 , 103 , 104 , the order of writing the strokes generally follows the same order described for the order of the shape elements. For example, the shape element 101 of FIG. 1B is written from top to down along a direction 156 (i.e., first the stroke 150 , and then the stroke 151 , the stroke 152 , and the stroke 153 , and finally, the stroke 154 ). [0022] Referring to FIG. 2 , a user 301 can readily input Chinese characters, like the Chinese character 100 of FIG. 1A , into an electronic device 200 using a keyboard 205 . The electronic device can be a mobile device, e.g., a smart phone, a tablet, etc. or can be a computing device, such as a word processor on a computer. The keyboard 205 can be an integral part of the electronic device 200 , e.g., a physical keyboard on a smart phone or a virtual keyboard on a tablet. The keyboard 205 can also be a separated from the electronic device, e.g., a stand-alone keyboard that connects to a computer. The keyboard 205 contains keys 208 , some of which correspond to English letters A-Z. An example of the keyboard 205 is a QWERTY keyboard. However, other keyboard 205 containing English letters or any manner of labeling representative of shape element families can also be used for inputting the Chinese characters. [0023] The input Chinese characters can be part of a text message, an email message, a document, etc. and can be displayed on a display 204 of the device 200 . The device 304 can be connected to the Internet 206 or a mobile network, through which the input Chinese characters can be delivered to other devices. [0024] The device 200 can include a processor 202 and storage devices such as memory that stores a database 203 . The storage devices can also store software that is executed by the processor 202 to enable the user 201 to input Chinese characters using the keyboard 205 . The software implements Chinese character input methods that correlate the strokes and/or shape elements with keys of the keyboard and that take into consideration the sequence of the writing of the shape elements. [0025] Referring to FIG. 3 , shape elements that frequently appear in commonly used Chinese characters, e.g., about 5,000 Chinese characters or more that are sufficient to enable typical communication to a Chinese reader, are grouped into 27 groups 300 - 326 . The shape elements are grouped according to their graphical similarities. For example, in the group 300 , all shape elements have a peak shape formed by a downward left stroke 330 and downward right stroke 331 that meet near or at the middle 332 . Details of the features of the groups 300 - 326 are summarized in Table 1 below. The shape elements in the same group can form subgroups that are displayed in rows. The shape elements in each subgroup have similar characteristics, e.g., have more similarities than those shape elements in different subgroups in the same group. For example, although all shape elements in three rows 391 , 392 , 392 of the group 300 contain the downward left stroke 330 and the downward right stroke 331 , the shape elements in the row 392 contain one additional stroke under the strokes 330 , 331 , the shape elements in the row 293 contain additional strokes above the strokes 330 , 331 , while the shape elements in the row 291 do not contain strokes in addition to the strokes 330 , 331 . The formation of the subgroups can help the user more easily remember the shape element groupings. In each group 300 - 326 , the shape elements that are most frequently used are listed in a top row 333 , from which a user referring to the grouping shown in FIG. 3 can find the most frequently used shape elements quickly. [0026] The groups 300 - 326 and the subgroup rows (including the top row) in each group can be arranged differently. For example, the groups 300 - 326 can be provided to a user (e.g., the user 201 of FIG. 2 ) in the form of a grouping table 340 of FIG. 3 or the grouping table 440 of FIG. 4 (discussed in detail below) to facilitate the user with inputting Chinese characters. Grouping the shape elements based on graphical similarities can reduce the amount of memorization the user has to use for learning the method of inputting the Chinese characters. In some implementations, additional shape elements can be added to the existing groups based on the shape of the additional shape elements to expand the number of Chinese characters the existing groups of shape elements allow a user to input. In some implementations, the method is a smart method that learns from a user's mistakes. For example, when the method or system detects that a user intends to input a shape element in the group 300 , but repeatedly (over a threshold number of times) makes mistakes by selecting the group 302 , the method or system can automatically infer the user's intended group selection, or allow a user to permanently move a particular shape element from one group to another group. Different users may customize their methods or systems differently. In some implementations, common mistakes can be reported and the methods and systems can be updated for future users. [0027] Referring to FIGS. 2 and 3 , the groups 300 - 326 are correlated to the keys 208 of the keyboard 205 . For example, each group 300 - 326 is associated with one distinct key, e.g., a virtual button on a touch screen digital device such as an iPad. In some implementations, each group 300 - 326 is associated with a distinct letter key, e.g., on a QWERTY keyboard (physical or virtual). The association and the groups are stored in the database 203 of the device 200 . As explained previously, the database 203 can be updated when the grouping of the shape elements are updated, e.g., based on use. [0028] In the example shown in FIG. 4 , each group 400 - 426 of shape elements is associated with one of the letter keys A-Z 430 a - 430 z and an additional key which corresponds to the “;” key (corresponding to group 419 ), such that the common shape of the group of shape elements resembles the shape of the associated letter. (The groups 400 - 426 are the same as the groups 300 - 326 of FIG. 3 , except that the groups 400 - 426 are arranged in a different sequence.) For example, the group 410 (corresponding to the group 300 of FIG. 3 ) has a common peak shape, while the letter A also contains a peak shape and visually look similar to some of the shape elements in the group 410 . The shape-based assignment of the groups to the letter keys can allow a user to memorize the assignment easily. [0029] The characteristics of the shape element groups (as shown in FIGS. 3 and 4 ) and their respective association with the keys of a QWERT keyboard (as shown in FIG. 4 ) are described in Table 1. [0000] TABLE 1 Common features of shape element in different groups. Group number and the associated key Common features of the shape elements in the group 300, 410, “A” A peak shape formed by a downward left stroke 330 and downward right stroke 331 that meet near or at the middle 332. Some of the shape elements resemble the letter “A”. 301, 424, “B” A vertical line on the left and one or two boxes attached to the vertical line. Some of the shape elements resemble the letter “B”. 302, 422, “C” A downward diagonal line to the left connected with horizontal strokes. Some of the shape elements resemble the letter “C”. 303, 412, “D” A two-part stroke that goes horizontally to the right then down, resembling the numeral “7”, with or without a downward vertical stroke to the left of the two-part stroke. Some shape elements look like the letter “D”. 304, 402, “E” Multiple horizontal strokes that make the shape elements resemble the letter “E”. 305, 413, “F” Two horizontal strokes. Some of the shape elements resemble the letter “F”. 306, 414, “G” Boxes stacked vertically or horizontally. 307, 415, “H” Two or more vertical lines, with or without one or more horizontal lines that cuts across the vertical lines, making the shape element resemble the letter “H”. 308, 407, “I” A vertical line, resembling the letter “I” or a horizontal curve that looks like a curved, rotated “I”. 309, 416, “J” A vertical line with a hook to the left at the bottom, resembling the letter “J”. 310, 417, “K” A vertical or diagonal line and a horizontal line extending from the middle of the vertical or diagonal line to the right, resembling the letter “K”. 311, 418, “L” A vertical line and a horizontal line extending from the bottom of the vertical line to the right, resembling the letter “L”. 312, 426, “M” The shape elements contain two parallel vertical lines with one or more horizontal lines between the vertical lines. Some shape elements resemble the letter “M”. 313, 425, “N” Two diagonal downwards to the right strokes, or two diagonal strokes going in opposite directions. Parts of the shape elements resemble a rotated letter “N”. 314, 408, “O” A box that resembles the letter “O”. 315, 409, “P” A vertical line and a horizontal line extending from the top of the vertical line to the right, resembling a part of the letter “P”. 316, 400, “Q” A box with a short line extending out from the box at the top or the bottom of the box. Some shape elements resemble the letter “Q” or an upside-down letter “Q”. 317, 403, “R” Two parallel vertical lines with at most three horizontal lines between the two vertical lines. Parts of the shape elements resemble the letter “R”. 318, 411, “S” A dash at the top and a horizontal line under the dash. 319, 404, “T” A horizontal line at the top and a vertical line that connects to or cuts through the horizontal line. Some shape elements resemble the letter “T”. 320, 406, “U” Two parallel vertical lines that are connected at the bottom by a horizontal line, resembling the letter “U”. 321, 423, “V” Two diagonal lines going in opposite directions, with the diagonal lines extending from a meeting point downwards to the left and right, or upwards to the left and right. Some shape elements resemble the letter “V”. 322, 401, “W” A horizontal line at the top, a vertical line intersects the horizontal line, and two diagonal lines extend from the intersection of the horizontal and vertical lines downwards to the left and right. Some shape elements resemble a rotated letter “W”. 323, 421, “X” Two diagonal lines that cross, forming an “X” shape. 324, 405, “Y” A vertical line, the bottom of which is connected to two diagonal lines extending downwards to the left and right. Some shape elements resemble an upside-down letter “Y”. 325, 420, “Z” There are three subgroups. The first subgroup contains shape elements that look like the letter “Z”. The second subgroup contains shape elements with one or more parallel diagonal lines. The third element contains shape elements with parallel vertical lines and several horizontal lines extending from the middle of the vertical lines. 326, 419, “;” Multiple dots. Some of the shape elements (semicolon) resemble the semicolon symbol, “;”. [0030] In some implementations, when the device 200 is operating in the mode for Chinese character input, the grouping of the shape elements, such as the table 340 of FIG. 3 , can appear on a touch screen of the device 200 , without associating the groups 300 - 326 to keys. Each group 300 - 326 becomes a button that can be activated. A user can look at the groups 300 - 326 and take time to search for the shape elements he/she intends to input. The user does not have to memorize the grouping or the key association with the groups. The groups 300 - 326 can be arranged in any format, e.g., table format, lines, columns, circles, or sections that appear on the touch screen simultaneously or at different times. In some implementations, the user can be allowed to arrange the groups according to the user's own preference. [0031] In some implementations, each group 300 - 326 can be represented by a symbol, e.g., one of the shape elements in each group, and the symbol may appear when the Chinese character input mode is activated. For example, the shape elements 345 - 371 could be used, respectively, to represent the groups 300 - 326 . [0032] The discussion below uses the key assignment of the groups shown in FIG. 4 as an example. In use, the user can turn the device 200 into the mode of Chinese character input. In this mode, each time a key that is associated with a group of shape elements is activated, the device 200 recognizes that the associated group shape elements is selected, instead of the English letter of the key. The user enters a Chinese character following the sequence of how the character is physically written. For example, the user activates a key containing the first shape element of the Chinese character he/she intends to enter, then chooses a key for the second shape element, and so on. When a series of keys has been activated followed by activating a designated key that indicates the entry is complete, e.g., a “space” key or any key that is not associated with any group of shape elements or a period of time has passed without receiving further activations, shape elements of different groups that correspond to the series of activated keys are combined and arranged based on the sequence of the key activations and the sequence of Chinese writing (i.e., generally from top to down and from left to right). The combinations and arrangements may produce one or more Chinese characters, which can be displayed to the user on the display 204 of the device. When multiple Chinese characters (candidates) are displayed, the user can choose the intended character by, e.g., clicking on the intended character, entering a numerical number, or other ways. [0033] Chinese characters and phrases can be input into a digital device efficiently with a limited number of keystrokes using the shape element grouping and shape element-key association discussed above. Each single Chinese character can be entered using at most three keystrokes that represent three of the shape elements contained in the character. In particular, the three keystrokes represent the first shape element, the second shape element, and the last shape element of the character in the sequence of writing the shape elements of the character. [0034] Chinese phrases containing two or more Chinese characters can be efficiently entered without requiring a user to enter all (three or fewer) keystrokes or shape elements required for each character. Instead, selected (less than all) keystrokes or shape elements of the characters can be concatenated into a string of keystrokes for inputting the Chinese phrases containing the characters. Generally, the string of keystrokes includes keys corresponding to the first two shape elements of the first two Chinese characters in the phrase. If the phrase includes three or more characters, the string of keystrokes includes additional keys corresponding to the first shape element of each additional character. [0035] For example, four or fewer keystrokes can be used to input a two-character phrase. The first two keystrokes enter the first two shape elements of the first character in the two-character phrase, and the next keystrokes correspond to the first two shape elements of the second character. To enter a three-character phrase, five or fewer keystrokes can be used, which correspond to the first two shape elements of the first character, the first two shape elements of the second character, and the first shape element of the third character. Six or fewer keystrokes can be used to input a four-character phrase, which correspond to the first two shape elements of the first character, the first two shape elements of the second character, the first shape element of the third character, and the first shape element of the fourth character. To enter a five-character phrase, six or fewer keystrokes are needed, which correspond to the first two shape elements of the first character, the first two shape elements of the second character, the first shape element of the third character, the first shape element of the fourth character, and the first shape element from the fifth character. [0036] The combination of the strokes (three or fewer for the single character, four or fewer for the two-character phrase, five or fewer for the three-character phrase, dix or fewer for the four or five-character phrase) can produce unique characters or phrases so that the characters or phrases can be entered without requiring the user to further select from lists of candidates. When occasionally there are multiple candidates corresponding to the series of input keystrokes, the number of candidates is typically small, e.g., less than four. The grouping of the shape elements, the selection of the shape elements to represent the characters (single or in phrases), and the features of the Chinese characters and phrases allows efficient input, so that user selection at the end of the input process amongst multiple candidate characters or phrases is rarely necessary. [0037] As an example, referring again to FIGS. 1 A and 2 - 4 , 5 A and 5 B, the shape elements 101 - 105 are in the groups 318 , 322 , 306 , 325 and 311 . Using the assignment of the groups and letter keys discussed with respect to FIG. 4 , a user first activates the letter key “S” that corresponds to the group 411 that contains the shape element 101 (first element in writing). The user then activates the letter key “W” that corresponds to the group 401 that contains the shape element 102 (second element in writing). The user then activates the letter key “L” that corresponds to the group 418 that contains the shape element 105 (last element in writing). The user then activates the “space key” or some other key to indicate the end of the character. [0038] If there is more than one Chinese character that corresponds to the given sequence of buttons, then all the applicable characters (or candidates) will be displayed so that the user can choose the desired character. For example, a three-key sequence, “D” ( 412 ), “M” ( 426 ), “D” ( 412 ) represents two different Chinese characters 179 , 189 illustrated in FIGS. 1D and 1E . The shape elements 180 , 181 , and 182 for the Chinese characters are in groups 412 , 426 , and 412 , respectively and should be entered in the sequence of DMD; the shape elements 183 , 184 , and 185 are also in groups 412 , 426 , and 412 respectively and should also be entered in the sequence of DMD. In the example shown in FIGS. 5A-5B , when a user enters the three-key sequence “DMD” (keys 512 , 526 , 512 ) in the keyboard 530 , the letter sequence “DMD” 532 appears in the editor window 531 . When the user presses the space key 527 , a drop-down menu 550 displays the Chinese characters 551 , 552 (corresponding to the characters 179 , 189 of FIGS. 1D-1E ) that match the “DMD” sequence. The user can select the desired character using a mouse 555 to control a cursor 554 . Other forms of display or selection can also be used. [0039] Alternative to a physical keyboard, referring to FIG. 6A , a user can also enter the Chinese character 179 ( FIG. 1D ) through a text entry application on a touch screen digital device 600 . The keys 603 , 604 , 605 , . . . , 630 can be arranged on the touch screen 601 in any order or form and can be labeled with English letters, shape elements, or others. In the example shown in FIG. 6A , the virtual keys are labeled with English letters. Based on the grouping shown in FIGS. 3 and 4 , the user activates a virtual key 606 (corresponding to the letter “D”) for the first shape element of the character 179 , followed by a virtual key 615 (corresponding to the letter “M”) for the second shape element, then a virtual key 606 (corresponding to the letter “D”) for the last shape element, and finally the virtual space key 631 . The letters “D”, “M”, “D” can appear 632 on an upper portion 632 of the touch screen 601 simultaneous to the user's activation of the respective virtual keys. When the space key is pressed ( FIG. 6B ), a drop-down menu 650 with all the Chinese characters that match the “DMD” sequence is displayed. The user selects the desired character by pressing on the screen at the location of the character, e.g., using a stylus or his/her finger(s). [0040] In some cases, a Chinese character can be represented by only one or two shape elements. To enter the Chinese character, only one or two keys are used, followed by the “space key”. For example, the Chinese character 161 illustrated in FIG. 1C contains a single shape element 160 , which is grouped in the group 404 of FIG. 4 and is associated with the letter key “T”. The Chinese character 161 can be entered by activating the key “T” followed by the “space” key. [0041] An example of inputting a two-character Chinese phrase 1100 shown in FIG. 10 is as follows. The phrase 1100 includes two characters 1010 and 1012 and is a commonly used phrase that means “bitter medicine”. Referring also to FIG. 4 , the three-key sequence that represents the shape elements 1000 , 1001 , 1002 of the first Chinese character 1010 is “HTO”, corresponding to the groups 415 , 404 , and 408 . The three-key sequence that represents the shape elements 1003 , 1004 , 1005 of the second Chinese character in FIG. 10B is “HNW”, corresponding to the groups 415 , 425 , and 401 . To enter the two-character phrase 1100 , a user activates the keys in “HTHN” corresponding to groups 415 , 404 , 415 , and 425 , followed by the space key. This phrase input method saves two key strokes over individually entering each character 1010 , 1012 (three keystrokes for each individual character). If a character only requires fewer than three shape elements in its representation, a padding key that is not associated with any group can be used to represent the missing shape element(s) in the phrase input. [0042] Similarly, entering a three-character Chinese phrase by concatenating the first two shape elements of the first character, the first two shape elements of the second character, and the first shape element of the third character can save four key strokes over individually entering three characters of the phrase; entering a four-character Chinese phrase by concatenating the first two shape elements of the first character, the first two shape elements of the second character, the first shape element of the third character, and the first shape element of the fourth character uses a six-key sequence, and can save six keystrokes over individually entering each of the four characters; Entering a five-character Chinese phrase by concatenating the first two shape elements of the first character, the first two shape elements of the second character, the first shape element of the third character, the first shape element of the fourth character, and the first shape element of the fifth character uses a seven-key sequence and can save eight key strokes over individually entering each character of the five characters. [0043] In some implementations, the candidates of Chinese characters can appear on the display before the entire series of keys are activated for a desired input. The user can choose to continue to input the keystrokes to reduce the number of candidates or to finish the entire series of keystrokes until the desired input is displayed, or can select the desired input from the displayed candidates. For example, when a first key stroke is activated, a list of candidates is displayed. The list may be long and the desired input may be at the end of the list that requires the user to flip pages of display to find the desired input. The user can look for and select the desired input. Alternatively, the user can continue with the series of keystrokes to reduce the number of candidates or finish the series of keystrokes to enter the desired input. The display of candidates can help users, particularly those who are not familiar with the all associations of the shape elements and the keys, to input Chinese characters or phrases. The system can be configured to recognize the completion of inputting a series of key strokes when a space key or other unmapped keys are activated after the mapped keys are activated, or when a predetermined amount of time lapses without further activation. The system enters the Chinese characters or phrases when the user actively selects the characters or phrases, or the system identifies the activation as complete. [0044] FIG. 7 shows an example of a process 700 in which a device implementing the method of this disclosure (such as the device 200 of FIG. 2 ) outputs Chinese characters upon receiving a user's input. Each character can be entered individually (one at a time), or as part of a phrase. In the Chinese input mode, a processor of the device receives 702 input key from a user and determines 704 whether the input key corresponds to the “space” key. If not, the processor will continue to receive additional input keys. Receipt of the “space” key allows the processor to determine that the user has finished entering a single character or a multi-character phrase. The processor counts the number of keystrokes received before the “space” key. If the number of keystrokes is determined 706 to be three, then the processor searches 708 in a database for all single characters that are represented by the three-key sequence entered and displays 710 all the found characters. Optionally, when there are more than one characters displayed, the processor enters 712 the character selected by the user. If the number of keystrokes is determined 714 to be four, then the processor searches 716 in the database for all two-character phrases that match the four-key sequence entered and displays 710 all the found two-character phrases. If the number of keystrokes is determined 718 to be five, then the processor searches 720 in the database for all three-character phrases that match the five keys entered and displays 710 all the three-character phrases that match. If the number of keystrokes is determined 722 to be six, then the processor searches in a database for all four-character phrases that match the six keys entered and displays 724 all the four-character phrases that match. If the number of keystrokes is determined 726 to be seven, then the processor searches 728 in the database for all five-character phrases that match the seven keys entered and displays 710 all the five-character phrases that match. If the number of keystrokes entered is higher than seven, the processor returns 730 an error and prompts the user to re-enter the keys. [0045] Modifications can be made to the process 700 . For example, some Chinese characters may be entered using less than three keys. In another example, the device can allow the user to enter more than one character or phrase at a time, e.g., an entire sentence continuously without any space key. As discussed previously, sometimes the device can simultaneously display candidates with the user's key entry before the space key. [0046] In some implementations, the device can update its database with new phrases, e.g., automatically based on the user's frequent usage of the phrases or by allowing the user to enter a mode (the “enter phrase”) to manually enter the new phrases into the database. Referring to FIG. 8 , an example of a process 800 in which a user updates the database manually. The processor of the device receives 802 an indication that the user has selected the “enter phrase” option to enter his/her own phases into the database. The processor then prompts 804 (e.g., on a display or screen) the user to enter the first character of a phrase and receives 806 three (or fewer) keystrokes representing the first character. After the processor retrieves and displays all characters that match the entered keystrokes to the user, e.g., using drop down menu 550 of FIG. 5B , the processor receives 807 an indication that the user selects a desired character. The processor then prompts 808 the user to enter the next character in the phrase to be added. The processor receives 810 three keystrokes representing the second character. After the processor retrieves and displays all characters that match the entered keys, the processor receives an indication that the user selects a desired character. The processor then provides 812 the user with the choice to continue adding another character or to add the phrase having the two entered characters. If the user chooses to add the phrase, the processor stores 814 the new two-character phrase in the database. If the user chooses to continue, the processor prompts 816 the user to enter a third character for the phase to be added. The processor enters the third character in a manner similarly to those of steps 806 , 807 or steps 810 , 811 discussed previously. After that, the processor provides 818 the user with the choice to continue adding another or to add the three-character phrase. If the user chooses to add the phrase, the processor stores 820 the new three-character phrase in the database. If the user chooses to continue, the processor prompts 821 the user to enter a fourth character for the phrase to be added. Again, similar to the first three characters, the processor enters the fourth desired character. The processor then provides 822 the user with the choice to continue adding another or to add the four-character phrase into the database. If the user chooses to add the phrase, the processor stores 824 the four-character phrase in the database. If the user chooses to continue, the processor prompts 826 the user to enter a fifth character for the phrase to be entered and enters the fifth character in a similar manner to those discussed for the previous four characters. The processor then stores 828 the five-character phrase in the database. In some implementations, the process 800 can be extended to allow the user to add phrases containing six or more characters. [0047] In some situations, when the user is connected to a server storing the central database for the Chinese character input methods or devices of other users, the server can be updated with the newly added phrases and can push the update to the database of devices of the other users. [0048] In some implementations, the processes, methods, and systems can be integrated with a Chinese-English dictionary application. The dictionary can be an electronic online dictionary or local to (downloaded and stored on) an electronic device. Software and database implementing the Chinese input methods of this disclosure can also be downloaded the user's device or reside on a server that provides the dictionary application. The methods of this disclosure can allow a user who is not very familiar with the Chinese language (e.g., meaning and pronunciation) to look up the meaning and pronunciation of Chinese characters or phrases. [0049] On a user interface 900 of FIG. 9 that implements the dictionary application, a user can input Chinese characters/phrases in a window 932 to look up the meaning of the character, which is displayed in the window 933 . For the purpose of discussion, we use the character 179 of FIG. 1D as an example. The user enters the keys “D”, “M”, and “D” using a keyboard 920 , followed by a “space” key 927 . A drop-down menu 934 shows two Chinese characters that match the key series “DMD”. The user selects the character 179 using a mouse 935 . The English meaning of the selected character is displayed in the text box 933 . A multi-character phrase can also be entered in 932 and its meaning will be displayed in 933 . In some implementations, the pronunciation of the entered characters or phrases is also shown. Other typical dictionary contents, such as sample use, can also be displayed. [0050] To use the Chinese character input methods of this disclosure, the user can download the software for use on his/her personal device, or can access, e.g., through Internet or other networks, a website that incorporate the methods in its software. The methods are machine-based, e.g., established on processors. Computer programs can be stored and executed by a machine to perform the methods. [0051] Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read only memory or a random access memory or both. The essential elements of a computer are a processor for executing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks. Information carriers suitable for embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto optical disks; and CD ROM and DVD-ROM disks. The processor and the memory can be supplemented by, or incorporated in special purpose logic circuitry. [0052] FIG. 11 is a schematic diagram of an example computer system 1350 . The system 1350 can be used for implementing the Chinese input methods discussed above. The system 1350 can include a processor device 1325 , a memory 1354 , a storage device 1356 , and input/output interfaces 1358 interconnected via a bus 1360 . The processor 1352 is capable of processing instructions within the system 1350 . These instructions can implement one or more aspects of the systems, components and techniques described above. In some implementations, the processor 1352 is a single-threaded processor. In other implementations, the processor 1352 is a multi-threaded processor. The processor 1352 can include multiple processing cores and is capable of processing instructions stored in the memory 1354 or on the storage device 1354 to display graphical information for a user interface on output monitor device 1362 . [0053] The computer system 1350 can be connected to a network 1366 , e.g., the Internet, through a network interface controller 1368 . The memory 1354 is a computer readable medium such as volatile or non-volatile that stores information within the system 1350 . The storage device 1356 is capable of providing persistent storage for the system 1350 . The storage device 1356 can include a floppy disk device, a hard disk device, an optical disk device, or a tape device, or other suitable persistent storage mediums. The storage device 1356 can store the various databases described above. The input/output device 1358 provides input/output operations for the system 1350 . The input/output device 1358 can include a keyboard, a pointing device, and a display unit for displaying graphical user interfaces. [0054] The computer system can be implemented in a computer, a hand-held device, a tablet, a cell phone, etc. [0055] An exemplary view of a computer system is shown in FIG. 11 , and is but one example. In general, embodiments of the subject matter and the functional operations described in this specification can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware. Embodiments of the subject matter described in this specification can be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a computer readable medium for execution by, or to control the operation of, data processing apparatus. The computer readable medium is a machine-readable storage device. The invention can be embodied in and/or or used with various apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, or multiple processors or computers.

Among other things, a method for use in causing Chinese characters that comprise shape elements to be constructed by an electronic device is described. A user is enabled to enter any of a set of Chinese characters sufficient to enable typical communication to a Chinese reader. The method comprises associating groups of shape elements with respective non-numerically associated touch locations of the electronic device, and upon receipt of an indication that one or more of the touch locations have been invoked, constructing a Chinese character based on the shape elements associated with the invoked touch locations. The shape elements are a complete set of shape elements from which all Chinese characters in the set are formed. Every one of the shape elements belongs to one of the groups. All shape elements in each group resemble each other in shape.

FIELD OF THE INVENTION [0001] This invention relates to systems and methods for providing function to otherwise paralyzed muscles. BACKGROUND OF THE INVENTION [0002] Functional Electrical Stimulation or Function Neuromuscular Stimulation, in short hand, typically refer to prosthetic systems and methods that restore function to muscles in the body that are otherwise paralyzed due to lack of neuromuscular stimulation, e.g., due to spinal cord injury, stroke, or disease. These conditions can break or otherwise disrupt the path or paths by which electrical signals generated by the brain normally travel to neuromuscular groups, to stimulate coordinated muscle contraction patterns. As a result, even though the nerves and muscles are intact, no electrical stimulation is received from the spinal cord, and the associated muscles do not function. Such systems and methods replace the disrupted, physiologic electrical paths, and restore function to the still intact muscles and nerves. Such systems and methods are known, e.g., to restore finger-grasp functions to muscles in the arm and hand, or to restore bladder and bowel control to muscles in the bladder, urethral sphincter, and bowel or to restore a standing function to muscles in the hip and thigh. [0003] Neuromuscular stimulation can perform therapeutic functions, as well. These therapeutic functions provide, e.g., exercise to muscle, or pain relief for stroke rehabilitation, or other surgical speciality applications, including shoulder subluxation, gait training, etc. [0004] While existing systems and methods provide remarkable benefits to individuals requiring neuromuscular stimulation, many quality of life issues still remain. For example, existing systems are function specific, meaning that a given device performs a single, dedicated stimulation function. An individual requiring or desiring different stimulation functions is required to manipulate different function specific stimulation systems. Such systems are not capable of receiving control inputs from different sources, or of transmitting stimulation outputs to different stimulation assemblies. Concurrent performance of different stimulation functions is thereby made virtually impossible. [0005] Furthermore, the controllers for such function specific systems are, by today's standards, relatively large and awkward to manipulate and transport. They are also reliant upon external battery packs that are themselves relatively large and awkward to transport and recharge. [0006] While the controller can be programmed to meet the individual's specific stimulation needs, the programming requires a trained technical support person with a host computer that is physically linked by cable to the controller. The individual requiring neuromuscular stimulation actually has little day to day control over the operation of the controller, other than to turn it on or turn it off. The individual is not able to modify operating parameters affecting his/her day-to-day life. [0007] It is time that systems and methods for providing neuromuscular stimulation address not only specific prosthetic or therapeutic objections, but also address the quality of life of the individual require neuromuscular stimulation. SUMMARY OF THE INVENTION [0008] The invention provides improved systems and methods for providing prosthetic or therapeutic neuromuscular stimulation. [0009] One aspect of the invention provides neuromuscular stimulation systems and methods that universally enable different, user-selectable neuromuscular stimulation functions. In one embodiment, the systems and methods employ a universal controller that is adapted to provide different functional neuromuscular stimulation functions, which can be selected by the user. The controller comprises a housing and an output device that is carried by the housing that can be coupled to an electrode. A microprocessor carried by the housing, which is coupled to the output device. The microprocessor includes a processing element that is operative in first and second modes. In the first mode, the processing element generates a signal pattern to an electrode to control a first neuromuscular stimulation function, e.g., a motor control function. In the second mode, the processing element generates a signal pattern to an electrode to control a second neuromuscular stimulation function that is different than the first neuromuscular stimulation function, e.g., a bladder or bowel control function. An input device carried by the housing is coupled to the microprocessor to enable selection by the user of the first or second modes. [0010] The input device desirably includes a display element on the housing. In this arrangement, the microprocessor is further operative to generate a display on the display element prompting selection of the first or second modes. [0011] The microprocessor can enable selection of either the first or second modes. Desirably, the microprocessor can enable concurrent selection of the first and second modes, so that, e.g., a user can affect a motor control function (for example, a standing function) while simultaneously affecting a bladder control function. [0012] Desirably, the housing is sized and configured to fit comfortably within a hand of the individual, or it can be otherwise sized and configured to be easily carried by the individual, e.g., in a shirt pocket or on a belt. [0013] The systems and methods that embody the features of the invention provide effective neuromuscular stimulation to meet a host of prosthetic or therapeutic objections. The systems and methods also provide convenience of operation, flexibility to meet different user-selected requirements, and transportability and ease of manipulation, that enhance the quality of life of the individual that requires chronic neuromuscular stimulation. [0014] Other features and advantages of the inventions are set forth in the following specification and attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0015] [0015]FIG. 1 is a diagrammatic view of a system that makes possible the restoration of function to muscles in the body that are otherwise paralyzed due to lack of neuromuscular stimulation; [0016] [0016]FIG. 2 is a diagrammatic view of a system that supports multiple prosthetic or therapeutic objectives, using a universal external controller, for achieving (i) a hand-grasp function in upper extremity arm muscles; (ii) a standing function in lower extremity leg muscles; and (iii) a bladder and bowel control function; [0017] [0017]FIG. 3A is a front view of the universal external controller shown in FIG. 2, showing the interface screen by which the user can select one or more neuromuscular stimulation functions; [0018] [0018]FIG. 3B is a bottom view of the universal external controller shown in FIG. 3A, showing the outputs for connecting different function-specific neuromuscular stimulation assemblies to the controller; [0019] [0019]FIG. 3C is a perspective view of the universal external controller shown in FIG. 3A, demonstrating how the compact size and configuration of the controller makes it well suited for hand-held operation; [0020] [0020]FIG. 4 is an exploded perspective view of the universal external controller shown in FIGS. 3A to 3 C; [0021] [0021]FIG. 5 is a representative circuit block diagram for the microprocessor housed within the universal external controller shown in FIGS. 3A to 3 C; [0022] [0022]FIGS. 5A to 5 M are schematic circuit diagrams of the principal circuit components of the microprocessor housed within the universal external controller shown in FIGS. 3A to 3 C; [0023] [0023]FIG. 6 is a view of an opening screen of the user interface that the microprocessor shown in FIG. 5 generates, prompting the user to select from a list of different stimulation functions that the universal external controller enables; [0024] [0024]FIG. 7 is a view of the hierarchy of the Exercise Regime screens of the user interface that the microprocessor shown in FIG. 5 generates, prompting the user to select from a list of different exercise stimulation functions that the universal external controller enables; [0025] [0025]FIG. 8 is a view of the hierarchy of the Finger-Grasp Pattern screens of the user interface that the microprocessor shown in FIG. 5 generates, prompting the user to select from a list of different finger grasp functions that the universal external controller enables; [0026] [0026]FIG. 9 is a view of the hierarchy of the screens of the user interface that the microprocessor shown in FIG. 5 generates, as the user affects different finger-grasp control functions using a shoulder position sensor as the control signal source; [0027] [0027]FIG. 10 is a view of the hierarchy of the screens of the user interface that the microprocessor shown in FIG. 5 generates, as the user affects different finger-grasp control functions using the keypad of the universal external controller as the control signal source; [0028] [0028]FIG. 11 is a view of the hierarchy of Set Up screens of the user interface that the microprocessor shown in FIG. 5 generates, which allow the user to select and change certain operating states or conditions of the user interface of the universal external controller; [0029] [0029]FIG. 12 is a schematic view of a remote programming system, which can be used in association with the universal external controller shown in FIGS. 3A to 3 C, to control, monitor and program the universal external controller; [0030] [0030]FIG. 13 is a view of the hierarchy of the screens of the user interface that the microprocessor shown in FIG. 5 generates, which allow the user or a trained technician to input programming instructions to the microprocessor, so that operation of the universal external controller can be customized and optimized; and [0031] [0031]FIGS. 14A to 14 D are diagrammatic views of the pulsed output command signals that the universal controller generates to conserve power and, thus, conserve battery life. [0032] The invention may be embodied in several forms without departing from its spirit or essential characteristics. The scope of the invention is defined in the appended claims, rather than in the specific description preceding them. All embodiments that fall within the meaning and range of equivalency of the claims are therefore intended to be embraced by the claims. DESCRIPTION OF THE PREFERRED EMBODIMENTS [0033] The various aspects of the invention will be described in connection with providing functional neuromuscular stimulation for prosthetic or therapeutic purposes. That is because the features and advantages that arise due to the invention are well suited to this purpose. Still, it should be appreciated that the various aspects of the invention can be applied to achieve other objectives as well. I. System for Providing Functional Neuromuscular Stimulation Using a Universal External Controller [0034] [0034]FIG. 1 shows a system 10 that makes possible the restoration of function to muscles in the body that are otherwise paralyzed due to lack of neuromuscular stimulation, e.g., due to spinal cord injury or stroke. Spinal cord injury or stroke can break or otherwise disrupt the path or paths by which electrical signals generated by the brain normally travel to neuromuscular groups, to stimulate coordinated muscle contraction patterns. As a result, even through the nerves and muscles are intact, no electrical stimulation is received from the spinal cord, and the associated muscles do not function. [0035] In use, the system 10 generates and distributes electrical current patterns to one or more targeted neuromuscular regions. The resulting patterns of neuromuscular stimulation restore desired muscle function in the targeted region or regions. The stimulatation can be achieved by direct application of electrical current to a nerve (e.g., using a nerve cuff electrode), or by indirect distribution of electrical current to a nerve through adjacent muscle tissue (e.g., using epimysial or intramuscular electrodes). [0036] As will be described in greater detail later, the system 10 can restore function to a single, targeted neuromuscular region, for example, to upper extremity muscles in the arm, e.g., to restore hand-grasp functions; or to lower extremity muscles in the leg, to restore standing or ambulatory functions; or to bladder and bowel muscles, to restore micturition; or to muscles controlling (in males) erection and ejaculation, or (in females) lubrication, to restore sexual or reproductive function. The system 10 can also be selectively operated to restore function to more than one targeted neuromuscular region, making it possible for an otherwise paralyzed individual to use the system 10 to selectively perform not only hand-grasp functions, but also to selectively perform standing/ambulatory and/or bladder and bowel control functions and/or other stimulation functions, as well. [0037] The system 10 comprises basic functional components that can be assembled and arranged to achieve single or several neuromuscular stimulation functions. Generally speaking, as shown in FIG. 1, the basic functional components for a prosthetic neuromuscular stimulation function include (i) a control signal source 12 ; (ii) a pulse controller 14 ; (iii) a pulse transmitter 16 ; (iv) a receiver/stimulator 18 ; (v) one or more electrical leads 20 ; and (vi) one or more electrodes 22 . [0038] As assembled and arranged in FIG. 1, the control signal source 12 functions to generate an output, typically in response to some volitional action by a patient, or a trained partner, or another care giver. In response to the output, the pulse controller 14 functions according to preprogrammed rules or algorithms, to generate one or more prescribed stimulus timing and command signals. [0039] The pulse transmitter 18 functions to transmit these prescribed stimulus timing and command signals, as well an electrical operating potential, to the receiver/stimulator 18 . The receiver/stimulator 18 functions to distribute electrical current patterns according to the prescribed stimulus timing and command signals, through the leads 20 to the one or more electrodes 22 . The one or more electrodes 22 store electrical energy from the electrical operating potential and function to apply electrical current patterns to the targeted neuromuscular region, causing the desired muscle function. [0040] The basic functional components can be constructed and arranged in various ways. In a representative implementation, some of the components, e.g., the control signal source 12 , the pulse controller 14 , and the pulse transmitter 16 comprise external units manipulated outside the body. In this implementation, the other components, e.g., the receiver/stimulator 18 , the leads 20 , and the electrodes 22 comprise implanted units placed under the skin within the body. Other arrangements of external and implanted components can occur, as will be described later. [0041] In the representative implementation shown in FIG. 2, a system 24 supports multiple prosthetic or therapeutic objectives. For purpose of illustration, in FIG. 2, the system 24 is capable of achieving (i) a hand-grasp function in upper extremity arm muscles; (ii) a standing function in lower extremity leg muscles; and (iii) a bladder and bowel control function. [0042] To accomplish the different hand-grasp, standing, and bladder and bowel control functions, the system 24 dedicates, for each function, a function-specific external control signal source 12 ( 1 )( 2 )( 3 ), a function-specific external pulse transmitter 16 ( 1 )( 2 )( 3 ), a function-specific implanted receiver/stimulator 18 ( 1 )( 2 )( 3 ), function-specific implanted leads 20 ( 1 )( 2 )( 3 ), and function-specific implanted electrodes 22 ( 1 ) ( 2 ) ( 3 ). To control all three function-specific receiver/stimulators, the system 24 employs a single, external pulse controller 26 , which, for this reason, will also be called the “universal external controller.” In concert with the other function-specific components, the universal external controller 26 selectively achieves all three hand-grasp, standing, and bladder and bowel control functions. A. The Function-Specific Hand-Grasp Function Components [0043] For the hand-grasp function, epimysial and intramuscular electrodes 22 ( 1 ) are appropriately implanted by a surgeon in the patient's arm. The function-specific implanted electrodes 22 ( 1 ) are positioned by the surgeon by conventional surgical techniques to affect desired neuromuscular stimulation of the muscles in the forearm and hand. [0044] Desirably, the neuromuscular stimulation affected by the electrodes 22 ( 1 ) achieves one or more desired palmar grasp patterns (finger tip-to-thumb pinching) and/or one or more desired lateral grasp patterns (thumb to flexed index finger pinching). The palmar grasp patterns allow the individual to grasp large objects (e.g., a cup or book), and the lateral grasp patterns allow the individual to grasp small or narrow objects (e.g., a pen or fork). [0045] Implanted leads 20 ( 1 ) connect the electrodes 22 ( 1 ) to the function-specific implanted receiver/stimulator 18 ( 1 ) in conventional ways. The receiver/stimulator 18 ( 1 ) is placed by a surgeon under the skin on the chest. The receiver/stimulator 18 ( 1 ) receives the stimulus timing and command signals and power from the universal external controller 26 through the function-specific external pulse transmitter 16 ( 1 ). [0046] In the illustrated embodiment, the pulse transmitter 16 ( 1 ) takes the form of a transmitting coil, which is secured to a skin surface over the receiver/stimulator 18 ( 1 ), e.g., by tape. The pulse transmitter 16 ( 1 ) transmits the stimulus timing and command signals and power through the skin to the receiver/stimulator 18 ( 1 ) for the hand-grasp function in the form of radio frequency carrier waves. The electrodes store electrical energy from the carrier waves. The stimulus timing and command signals for the standing function are distributed as biphasic current pulses in discrete channels to individual implanted electrodes 22 ( 1 ). The biphasic pulses provide amplitude and duration electrical signals that achieve the desired coordinated muscular finger-grasp function. Because the implanted receiver/stimulator 18 ( 1 ) receives power from universal external controller 26 through the external pulse transmitter 16 ( 1 ), the implanted receiver/stimulator 18 ( 1 ) requires no dedicated battery power source, and therefore has no finite lifetime. [0047] The external control source 12 ( 1 ) for the hand-grasp function is coupled to the universal external controller 26 . As will be described in greater detail later, the external controller 26 can support a variety of external control sources 12 ( 1 ), which can be coupled to the controller by cable or by wireless link, as will also be described in greater detail later. [0048] In the embodiment illustrated in FIG. 1, the external controller 12 ( 1 ) comprises a mechanical joy stick-type control device, which senses movement of a body region, e.g., the shoulder, which is therefore also called a shoulder position sensor. The shoulder position sensor can comprise, e.g., a two axis angle transducer that measures motion of the shoulder relative to the chest. The shoulder position sensor can be secured to the skin of the shoulder in the region of the sternal notch and clavicle using tape. As will be described later, when the user manipulating the shoulder in predetermined ways, the shoulder position sensor generates functional or proportional signals that, when processed according to the pre-programmed rules of the controller 26 , select or deselect either palmar or lateral grasp patterns, proportionately control of the opening and closing of the hand, or lock the hand in a desired grasping position. As will be described in greater detail later, in an alternative implementation, manipulation of input buttons on the universal external controller 26 also can be used to perform these finger-grasp functions. [0049] Further details of these function-specific components for the hand-grasp function can be found in Peckham et al U.S. Pat. No. 5,167,229, which is incorporated herein by reference. Commercial examples of such function-specific components can also be found in the FREEHAND™ System, sold by NeuroControl Corporation (Cleveland, Ohio). B. The Function-Specific Standing Function Components [0050] For the standing function, epimysial and intramuscular electrodes 22 ( 2 ) are appropriately implanted by a surgeon in the patient's upper leg. The function-specific implanted electrodes 22 ( 2 ) are positioned by the surgeon by conventional surgical techniques to affect desired neuromuscular stimulation of the muscles in the hip and thigh. [0051] Desirably, the neuromuscular stimulation affected by the electrodes 22 ( 2 ) achieves a contraction of leg muscles in the hip and thigh to bring the individual to an upright and standing position. In this position, the individual can stand upright and move about, typically with the aid of a walker or arm crutches. [0052] Implanted leads 20 ( 2 ) connect the electrodes 22 ( 2 ) to the function-specific implanted receiver/stimulator 18 ( 2 ) in conventional ways. The receiver/stimulator 18 ( 2 ) is placed by a surgeon under the skin in the abdomen or thigh. The receiver/stimulator 18 ( 2 ) receives the stimulus timing and command signals and power from the universal external controller 26 through the function-specific external pulse transmitter 16 ( 2 ). [0053] As in the finger-grasp function, in the illustrated embodiment, the pulse transmitter 16 ( 2 ) for the standing function takes the form of a transmitting coil, which is secured to a skin surface over the receiver/stimulator 18 ( 2 ), e.g., by tape. The pulse transmitter 16 ( 2 ) transmits the stimulus timing and command signals and power through the skin to the receiver/stimulator 18 ( 2 ) for the standing function in the form of radio frequency waves. As in the finger-grasp function, the stimulus timing and command signals for the standing function are distributed by the receiver/stimulator 18 ( 2 ) in discrete channels to individual implanted electrodes 22 ( 2 ) and provide electrical amplitude, duration, and interval command signals that achieve the desired coordinated muscular standing function. [0054] The external control source 12 ( 2 ) for the standing function is coupled to the universal external controller 26 . As explained earlier in the context of the finger-grasp function, the universal external controller 26 can accommodate input from a variety of other external control sources, either by hard-wire or wireless links. In the illustrated implementation, the external control source 12 ( 2 ) comprises a remote control button accessible to the individual, by which the user (or care giver) can select or deselect the standing function. One or more input buttons on the universal external controller 26 itself can also be used to select and deselect the standing function. C. The Function-Specific Bladder and Bowel Control Function Components [0055] For the bladder control function, cuff electrodes 22 ( 3 ) are appropriately implanted by a surgeon about sacral nerves that lead to the bladder and bowel. The function-specific implanted electrodes are positioned by the surgeon by conventional surgical techniques to affect neuromuscular stimulation of muscles in the bladder, bowel and urethral sphincter. [0056] Desirably, the neuromuscular stimulation affected by the electrodes 22 ( 3 ) achieves a contraction of the muscles of the bladder, urethral sphincter, and bowel. After the bladder has contracted in response to the neuromuscular stimulation, it is possible to relax the sphincter muscles, allowing the bladder to empty. [0057] Implanted leads 20 ( 3 ) connect the electrodes 22 ( 3 ) to the implanted receiver/stimulator 18 ( 3 ) in conventional ways. The receiver/stimulator 18 ( 3 ) is placed by a surgeon under the skin in the abdomen. The receiver/stimulator 18 ( 3 ) receives the stimulus command signals from the universal external controller 26 through the external pulse transmitter 16 ( 3 ). [0058] As with the finger-grasp and standing functions, in the illustrated embodiment, the pulse transmitter 16 ( 3 ) takes the form of a transmitting coil, which is secured to a skin surface over the receiver/stimulator 18 ( 3 ), e.g., by tape. The pulse transmitter transmits the stimulus command signals through the skin to the receiver/stimulator 18 ( 3 ) for the bladder and bowel control function in the form of radio frequency waves. [0059] As explained earlier in the context of the finger-grasp and standing functions, the universal external controller 26 can accommodate input from a variety of other external control sources 12 ( 3 ), either by hard-wire or wireless links, to also affect the bladder and bowel control function. In the illustrated implementation, the external control source 12 ( 3 ) for the bladder and bowel function comprises an external remote control device, that can select or deselect the bladder and bowel control function. One or more input buttons on the universal external controller 26 itself can also be used to select and deselect the bladder and bowel control function. [0060] Further details of these function-specific components for the bladder and bowel control function can be found in Brindley U.S. Pat. No. 3,870,051, which is incorporated herein by reference. Commercial examples of such function-specific components can also be found in the VOCARE™ System, sold by NeuroControl Corporation (Cleveland, Ohio). D. The Universal External Controller [0061] As FIGS. 3A, 3B, 3 C, and 4 show, the universal external controller 26 is desirably housed in a compact, lightweight, hand held housing 28 . In one implementation, the housing 28 measures about 9.5 cm by 5.6 cm×2.7 cm, and weighs, e.g., about 160 g. As such, the controller 26 readily fits into a pocket or can be clipped onto the belt of an individual. [0062] Desirably, the controller 26 is battery powered. In the illustrated embodiment, the controller 26 includes a power input slot that receives an interchangeable, rechargeable, industry-standard battery 30 (see FIG. 4), e.g., a Lithium Ion battery used in association with a MOTOROLA™ Star Tech™ Cellular Phone. The controller 26 desirably interchageably accommodates rechargeable batteries of various capacities, so that different power usage levels of the controller (depending upon the number and type of prosthetic functions of the controller 26 ) can be readily supported. [0063] Desirably, the battery 30 cannot be charged when connected to the universal external controller 26 , so that the controller 26 (and, thus, the user) cannot be connected to main power. Instead, the battery 30 must be removed and coupled to an associated external battery charger (not shown). [0064] The controller 26 also desirably includes a display screen 32 and keypad 34 , which together form an interactive interface between the individual user and the controller 26 . The display 32 can comprise, e.g., a liquid crystal display. The display 32 presents to the individual pertinent operational and status information, and also prompts the individual to select or modify operational settings using the keypad 34 . The keypad 34 can comprise, e.g., a one-piece silicone-rubber molded unit. [0065] The controller 26 desirably houses a microprocessor 36 , which, in the illustrated embodiment (see FIG. 4), is implemented on a main, double-sided circuit board 38 . The main circuit board 38 carries the components of the microprocessor 36 , e.g., high and low voltage supplies, a high voltage protector, input/output ports 112 (shown in FIG. 3B) and drivers for the external control signal sources and pulse transmitters, a microcontroller, keypad interface, the liquid crystal display 32 , and an audio device (e.g., a buzzer). The microprocessor 36 also desirably includes a 900 MHz transceiver, to allow wireless linking between the controller 26 and a compatible external wireless control signal source 12 ( 1 ) ( 2 ) ( 3 ), as will be described in greater detail later. If desired, additional full size or half-size circuit boards 40 (see FIG. 4) can be optionally provided, to handle special input signal conditioning for one or more of the function-specific control signal sources (e.g., the joy stick-type shoulder position sensor). [0066] The microprocessor 36 can be realized with, e.g., a conventional MC68HC12 microcontroller. The microprocessor 36 also desirably includes a flash memory device on the main circuit board 38 , which can be realized with e.g., a conventional EEPROM memory chip. The flash memory device carries embedded, programmable code, which will also be call the “firmware.” The firmware expresses the pre-programmed rules or algorithms under which the stimulation timing and command signals are generated in response to input from the various external control sources, as well as the pre-programmed rules or algorithms that govern operation of the display 32 and keypad 34 of the controller 26 to create the user interface, as well as the other input/output devices supported by the controller 26 . [0067] The microprocessor 36 of the controller also desirably includes an infrared transceiver. The transceiver allows the wireless transfer of information to and from the microprocessor through an optical lens 42 (see FIGS. 3C and 4). This makes possible wireless programming of the firmware by infrared link by an external computer, as will be described later. This also makes possible wireless linking between two or more controllers 26 , for exchange of information and for replacement and backup purposes. As will be described later, the microprocessor 36 also accepts programming input via the input keypad 34 , allowing the individual user or care giver to program operation of the controller 26 to the extent permitted by the firmware. [0068] In the illustrated embodiment, the housing 28 encloses the display 32 , keypad 34 , and circuit board(s) 38 and 40 between front (keypad side) and rear (battery side) housing shells 44 and 46 , which can be made, e.g., from molded ABS impact-resistant plastic. Spash-proof gaskets 48 are desirably placed at appropriate places, e.g., about the keypad, battery contacts, and housing shells, to seal the housing 28 against ingress of moisture. A LCD lens window 50 desirably covers the display 32 . Pivots 52 for a conventional flip cover can also be provided on the housing 28 . 1. Main Circuit Board Components [0069] [0069]FIG. 5 shows a representative circuit block diagram for the microprocessor 36 of the universal external controller 26 . The specific circuitry shown in FIG. 5 allows the selection of a desired neuromuscular stimulation objective and supports the generation of output signals to one neuromuscular stimulation assembly to achieve the objective. However, it should be appreciated that the circuitry can be modified to include multiple parallel output stages, so that concurrent outputs to different neuromuscular stimulation assemblies can be provided. [0070] As shown in FIG. 5, the circuitry is built on two printed circuit boards: the main circuit board 38 and the auxiliary board 40 . FIGS. 5A to 5 M show representative circuit schematics for the components carried on the two boards 38 and 40 . [0071] The main circuit board 38 consists of five circuit modules. These are (see FIG. 5) the power supply module 200 , the implant driver module 202 , the microcontroller module 204 , and the user interface module 206 . The representative implementation mounts these modules on a double-sided, 6-layer FR 4 printed wiring main circuit board 38 (88 mm×49 mm). [0072] In the illustrated embodiment, the functions supported by the main circuit board 38 include: (i) mounting of push buttons of the keypad 34 for user control; (ii) mounting of the display 32 and audio device for user prompting and information display; (iii) mounting of contacts for user serviceable battery 30 ; (iv) mounting of output plug contacts for the indicated function-specific pulse transmitters; (v) an interface to auxiliary control boards 40 , e.g., for specialized function-specific control signal sources 12 ( 1 ) ( 2 ) ( 3 ); (vi) control of processing functions via the microprocessor 36 and memory chip; (vii) interface to the keypad 34 , display 32 , audio device, and other user interfaces to the microprocessor 36 ; (viii) drivers for the indicated function-specific pulse transmitters 16 ( 1 )( 2 )( 3 ); (ix) interface to the battery 30 , including detection of battery charge status; (x) provision of an infrared communications link; and (xi) provision of a 900 MHz communications link. [0073] Various circuit components and configurations can be placed on the main board to realize these and other functions. A representative implementation will be generally described with reference to FIGS. 5A to 5 M and associated tables. The representative implementation meets medical grade IPC standard design rules, using no wires and all standard components, except one custom made transformer. The representative implementation uses no adjustable components, except one trim capacitor (to accommodate variations in the one custom made transformer). The representative implementation is EMC compatible. [0074] The Power Supply Module 200 includes a low-voltage supply circuit 208 (shown schematically in FIG. 5A) and a high-voltage supply circuit 210 (shown schematically in FIG. 5B). The low-voltage supply circuit 208 converts the battery voltage of 2.7 to 4.2 V to the general circuit operation voltage of 5.0 V. The high-voltage supply circuit 212 converts the same battery voltage to the variable operating voltage for the implant drivers (5.0 to 8.5 V for the finger-grasp and standing functions, and 10 to 40 V for the bladder/bowel control function). Each voltage supply circuit 208 and 210 is a DC/DC converter built around a specific IC chip. The level of the high voltage is set by the microcontroller module 204 via a DAC. A high-side current sensing IC provides output current value to the microcontroller module 204 . [0075] The Implant Driver Module 202 includes the function-spicific driver 212 for the bladder and bowel control function (FIG. 5D), the function-specific driver 214 for the hand-grasp function (FIG. 5E), and the function-specific driver 216 for the standing function (FIG. 5F), with an associated high voltage protector (FIG. 5C), to provide failsafe hardware protection. The hand-grasp and standing function drivers 214 and 216 generate amplitude-modulated carrier of 6.78 MHz for powering and communicating with the implanted function-specific receivers/stimulators, respectively 18 ( 1 ) and 18 ( 2 ). As will be described in greater detail later, the output RF for each of these drivers 214 and 216 can be set by the user at one of five levels between 0.5 to 1.0 W. This variable RF power setting ensures reliable coupling to the associated implanted function-specific receiver/stimulator 18 ( 1 ) or 18 ( 2 ) at the specific depth of implantation (which can vary), while minimizing battery consumption. The bladder and bowel control driver 212 generates high voltage (10 to 40 V), high current (up to 1 A) pulses to excite the associated receiver/stimulator 18 ( 3 ). Three identical output stages can be controlled by the microcontroller module 204 for interfacing with either a 3-channel or a 2-channel receiver/stimulator 18 ( 3 ). The function of the high-voltage protector 218 is to prevent accidental application of high voltage to the finger-grasp or standing drivers 214 to 216 in case of a firmware failure. [0076] The Microcontroller Module 204 (schematically shown in FIG. 5G) is built around a Motorola HC12 chip. The HC12 chip has 1-kbyte RAM and 32-kbyte flash EEROM. The built-in flash memory is used for the system firmware. An external 8-kbyte EEPROM chip is used for user-specific data, such as for finger-grasp patterns (as will be described later). A 4-MHz ceramic resonator is selected for obtaining a 2-MHz clock frequency in the HC12. The HC12 uses a synchronous serial peripheral interface (SPI) to communicate with three peripheral chips: the LCD display driver; the DAC for high-voltage setting; and the ADC in the auxiliary board 40 (as will be described later. The HC12 also uses an asynchronous serial communication interface (SCI) to communicate with the infrared transceiver 220 (shown schematically in FIG. 5K) and the 900-MHz transceiver 222 (shown schematically in FIG. 5L). The internal 8-channel, 10-bit ADC of the HC 12 is used to monitor the critical parameters such as battery voltage, output voltage to the low-voltage supply 208 , output voltage and output current of the high-voltage supply 210 , and the received signal strength of the 900-MHz transceiver 222 . [0077] The User Interface Module 206 consists of the circuitry 224 for the keypad 34 (shown schematically in FIG. 5H), the circuitry 226 for the liquid crystal display (LCD) 32 (shown schematically in FIG. 5I), and the circuitry 222 for the 900-MHz transceiver (shown in FIG. 5L). In the keypad circuit 224 , a pair of perpendicularly situated reed switches is connected in parallel to each of the regular pushbutton switches for the “enter” and “exit” functions, as will be described later. The reed switches allow the user to operate the device using a finger ring with a magnet, without having to physically touch the keypad 34 . The LCD circuit 226 has a 16 character×4 roll screen 32 with LED back lighting. The volume of the sound generated by the buzzer circuit 228 (shown schematically in FIG. 5J) is adjustable by changing the pulse width. The infrared transceiver 220 (shown schematically in FIG. 5K) is implemented with a transceiver IC and discreet transmitting LED and receiving photo diode. The 900 MHz transceiver (shown schematically in FIG. 5L) is formed with a loop antenna, an amplitude-sequenced hybrid (ASH) transceiver module, and a dedicated microcontroller chip for decoding the received commands. Input and output level shifters are used for interfacing the 3-V transceiver module 222 with the 5-V HC12 microcontroller. [0078] In the representative implementation, the controller also includes a double-sided, 6-layer FR4 printed wiring board 40 (40 mm×46 mm) (shown schematically in FIG. 5M), which serves as an input signal conditioning card for a joy-stick type shoulder position sensor, which is used in the illustrated embodiment to carry out the finger-grasp function. The main board 38 and auxiliary board 40 are connected together through a 30-contact interboard connector 240 . The auxiliary board 40 includes an input filter 230 having low-pass filters and surge suppressors for improving immunity to electromagnetic interference. The auxiliary board 40 also includes a differential amplifier 232 , which has two instrumentation amplifier IC chips set a gain of 10 for both X and Y axis signals coming from the shoulder position sensor. The auxiliary board 40 also includes a an analog-to-digital converter 234 , which is a 2-channel, 12-bit serial ADC chip. A power supply 236 on the board 40 uses a charge-pump IC to convert battery voltage to the 5 V excitation level for the shoulder position sensor. The 5 V output is pulsed at a duty cycle of {fraction (1/16)} to conserve battery power. The board 40 also includes switch interface relays 238 , which relays the two external switches to the microcontroller module 204 , while also providing the signal about the connection of the sensor or the switches. [0079] The following tables describe for ready reference further details of the components and their functions as shown in FIGS. 5 and 5A to 5 M. TABLE 1 The Low Voltage Supply Circuit 208 (FIG. 5A) Component Description Circuit Function F1101 THERMAL Limits magnitude and SWITCH/FUSE duration of over voltage 1.1 A clamped currents from battery input D1101 DIODE, ZENER Protects LV Regulator and 5.6 V VDD powered devices (CPU) from static discharge and accidental over voltage C1101, Capacitors Filter noise fed back to C1102 battery voltage network R1101, Resistors Divider for CPU VBAT R1102 monitor input U1101 PWM DC/DC Provides control and Power Up power switching for Low Converter Voltage Flyback power converter C1103 Capacitor Filters switching noise within and to U1101 regulator R1104, R-C Network Pull-Up (dissable) and C1104 flitch filter for PENTER/V LV ONB (active low) R1103 Resistor Pull-Down (dissable) VDDON ONA (active high) L1101 Inductor, Dynamic energy storage Power for power conversion D1101 Rectifier, Switch mode communtating Schottky 40 V, Rectifier 400 mA C1105 Capacitor Switching Output Filter R1105, Resistors Low Voltage Switching R1106 Regulator feedback sense divider R1107, Resistors Low Voltage Linear R1108 Regulator feedback sense divider C1106 Capacitor Linear Output Filter [0080] [0080] TABLE 2 The High Voltage Supply Circuit 210 (FIG. 5B) Component Description Circuit Function C2101 Capacitor Filter HV Converter noise fed back to battery voltage network M2102 Power MOS FET, HV Converter battery P Ch power switch M2101 Power MOS FET, Gate drivers for M2102 N Ch R2101, Resistors Gate drivers networks for R2102 M2102 and M2102 U2101 PWM DC/DC Provides control and Power Up drive for High Voltage Converter Flyback power converter C2102-C2104 Capacitors Filters switching noise within and to U2102 regulator R2103 Resistor Sets basic switching frequency for U2101 regulator R2104, R-C Network Supply +5 V, (VDD) to C2105 U2101 and decouple VMOS gate drive noise from MPU supply B2101, R-C Network Supply VBAT to storage C2106, −7 inductor L2101 and decouple power switching noise battery voltage network L2101 Inductor, Dynamic energy storage Power for power conversion M2103 Power MOS FET, Power converter switch N Ch R2105 Resistor, Low W Current Sense, PWM control, limit D2101 Rectifier, Switch mode communtating Schottky 60 V, Rectifier 1.0 A C2108, Capacitors Switching Output Filter C2109 R2106, Resistors High Voltage feedback R2107, Potentiometer, sense divider with CPU U2102 Digital 32 pos control through setting linear or the digital Pot R2108, R-C Network Power up preset network C2110 for U2102 U2103 Transconduct- Translates current sense ance Current voltage across pins 2-7 Sense Amp input to ground reference signal R2109 Resistor Current sense Scaling Resistor C2112 Capacitor Output noise filter R2111-R2113 Resistor Divides HV level for CPU Divider Net HV monitor input and Free hand HV upper limit [0081] [0081] TABLE 3 The Bladder and Bowel Control Function Driver 212 (FIG. 5D) Component Description Circuit Function D2201-D2204 ZENER Protects HV Power and TRANSIENT VOCARE Switches from CLAMP DIODE transient discharge and loss of HV converter control C2201, Capacitors Filter HV Converter noise C2302 and provide energy reservoir for VOCARE pulse load M2202B Power MOS FET, HV Converter switch for P Ch Free Hand Driver M2202A, Power MOS FET, HV Converter switch for M2205A, B P Ch VOCARE Coils C, B, A M2201, −3, −4, Power MOS FET, Gate drivers for M2202 −6 N Ch and M2205 R2203-R2214 Resistor Gate drivers networks for M2202 and M2205 U2201 Comparator Conditioned switch for HV to Free Hand Driver R2201, Resistor Divides logic level to R2202 Divider match HV upper limit sense voltage above which Free Hand high voltage will not switch on [0082] [0082] TABLE 4 The Hand-Grasp Function Driver 214 (FIG. 5E) and the Standing Function Driver 216 (FIG. 5F) Component Description Circuit Function U2301 Crystal Controls Power Drive Oscillator Frequency Module, 13.5600 MHz U2302 Dual Flip Flop Divide Oscillator by 2 for 6.78 MHz ISM frequency and bi-phase drive for Class B output stage R2301, Resistors Rf isolated logic input R2304 networks U2303 AND Gate Output Stage Gate Driver Buffers R2306-R2308 Resistors Gate Drive Hi-Low Through current limiters R2309, Resostors Gate Pull-Downs R2310 M2301, Power MOS FETs Class B Power Amplifier M2302 C2307-C3211 Passive Filter Harmonic and Radiated L2301-L2303 Emission Suppression C2305, Capacitors Local RF Bypass C2305 B2301-B2305 Ferrite Beads Radiated Emission Suppression R2302 Resistor Connection to DC continuity coil check C2312 Capacitor RF Filter [0083] [0083] TABLE 5 The Microcontroller Module 204 (FIG. 5G) Component Description Circuit Function C1201-C1205 Capacitors Microcontroller supply bypasses C1206 Capacitors Local bypass for POWER RESET chip, U1202 U1201 Microcontroller Provides all system control and interface D1201, R-Diode Network Programming Pulse R1202 Interface D1202 Diode Prevents Input drive when MPU is powered down Y1201, Quartz crystal, MPU Clock reference and R1201 4.0 MHz and associated bias resistor resistor R1203, C1208 R-C Networks A/D Converter input thru R1210, Filter networks C1215 C1216-C1222 Capacitors Spike filters on operator switch inputs U1202 IC, Power Monitors VDD and reset Monitor Reset on power drops below 4.4 volts for 20 msec U1203 IC, 2.50 volt Provides 2.5 volt A/D ref reference C1207 Capacitor Noise Filter for A/D ref R1211-R1213 Resistors Serial Buss Pull-Downs R1222, R-C Network Pull-Up for Implant Coil R1223 Continuity check input R1224, Resistors Daughter Bd. TP1, 2 Pull- R1225 downs U1204 IC, Serial Alterable non-volatile EEPROM memory for setup preferences R1214 Resistor Chip Select Pull-up (inactive) U1205 IC, IR and RS- Provides serial IR send 232 interface receive functions D1203 LED, IR IR link IR emitter R1216 Resistor Sets IR LED operating current C1225 Capacitor Local bypass for IR transmit switching noise C1224 Capacitor Local bypass for IR/RS- 232 power D1203 Diode, IR photo IR link IR detector R1215, −17- Resistors Pull-Downs for U2105 18 control and data lines U1208 IC, remote Decodes encrypted button control application data encrypte/decode chip C1226 Capacitor Local bypass for remote control chip power R1220, Resistors Pull-downs for U1208 R1221 control and data lines U1206, IC, 2-way MPX Telemeter and IR U1207 switch communications to one set of MPU lines R1219 Resistor Pull-downs for TEL-IR control line J1201 2 × 15 Pos. Option Daughter Board Female Jack [0084] [0084] TABLE 6 The User Interface Module (FIG. 5H) Component Description Circuit Function U1301 IC, 3.0 V Switches buzzer power regulator C1301 Capacitor Local bypass for buzzer regulator C1302 Capacitor Filters switching noise within buzzer regulator C1303, Capacitors Regulator Output C1309 Filters R1301, Resistors MPU interface and Pull- R1308 Down D1301 Diode Inductive spike clamp LS1301 Sound Provides Audible Signal Transducer U1302 LCD Module Provides Visual User interface C1304 Capacitor Local bypass for LCD Module R1302 Resistor LCD (Chip Sel) Pull-Up (inactive) R1303, Resistors LCD and interface bias R1304 U1303 IC, 3.0 V Switches buzzer power regulator C1305 Capacitor Local bypass for buzzer regulator C1306 Capacitor Filters switching noise within buzzer regulator C1307, Capacitors Regulator Output C1308 Filters R1306, Resistors MPU interface and Pull- R1307 Down SW1301- SPST, MOM Push User interface Buttons SW1312 SW1309- SPST, MOM Mag Alternate Control Mode SW1312 Reed U1202 IC, Power Monitors VDD and reset Monitor Reset on power drops below 4.4 volts for 20 msec J1301 ZIF Jack, LCD Jack Ribbon [0085] [0085] TABLE 7 The Infrared Transceiver 220 (FIG. 5K) Component Description Circuit Function C1401 Capacitor Filter noise fed back to VDD R1401 Resistor Pull-Down (disable) TEL, SHD (active <OFF> low) U1401 Linear Low Drop Provides +3.0 volts for Regulator Transceiver Module, U1402 C1402 Capacitor Filters switching noise within U1401 C1403, Capacitors Regular Output Filters C1409 R1403 Resistor Transmit, TELTXD Hi-Z pull-down R1404 Resistor Transmit power set R1402, R-C Network AGC Bias Supply and C1404 bypass C1405 Capacitor Peak Detector Attack- Decay time constant R1403 Resistor VBBO load isolation resistor R1405 Resistor Sets Bandwidth of Baud Rate Low Pass Filter R1406, Resistors Pull-ups for CT0 and CT1 R1108 Mode R1401 Resistor RX DDATA Pull-Down U1403 Single 74 HCT Level translates RX DATA equivalent OR to 5 volt logic Gate C1406, Capacitors Antenna Tuning C1407 ANT1401, −02 Metal strips Telemeter antenna elements C1408 Capacitor Antenna match [0086] [0086] TABLE 8 The Input Filter 230 (FIG. 5M) Component Description Circuit Function J4101 Jack, 14 pos, Shoulder Position Female Transducer Module Input B1401 Ferrite Bead, 1 × 10 Common Mode Choke, 10 Lines EMI suppression DS4101- ZENER, Protects Shoulder DS4109 TRANSIENT Position Diff. Amp. from CLAMP 9 V transient discharge L4101, L-C Networks Filter DC Power and L4103, Ground lines to external C4101, C4110 Shoulder position and L4102, Transducer Module L4104 C4102, C4111 R4109, R4116 R-C Networks Filter Differential X C4103, C4112 and Y Signal and three thru R4115, switch closure signal R4122 C4109, lines from external C4118 Shoulder position Transducer Module R4108, R4123 Zero Ω Jumpers EM Immunity Test Jumpers [0087] [0087] TABLE 9 The Differential Amplifier 232 and A-D Converter 234 (FIG. 5M) Component Description Circuit Function U4102, IC, Shoulder Position U4104 Instrumentation Transducer Amplifier Differential Amp F4205, −6 Resistors Input pull down load, R4208, −9 Amplifier C4209, Capacitors Differential low pass C4210 filter R4207, Resistors Gain Set, Differential R4210 Amplifier U4203, IC, Reference, Pseudo Ground for U4102, U4205 2.5 V U4104 C4204, Capacitors Pseudo Ground noise C4205 Filter U4201 IC, Step up Provide switchable low Charge Pump noise power to Shoulder w/Linear Position Transducer and Regulator Amplifier R4204 Resistor SHD input over drive protection C4201 Capacitor Local Bypass of noise fed back to battery voltage C4202 Capacitor Charge Pump C4203 Capacitor Regulator Output Bypass U4206 A/D Converter, Provides expanded 12 Bit/2 Ch resolution of Shoulder Serial Position Amplifier Output U4207 IC, Ref., Full scale ref., for 4.096 V U4106 A/D C4206 Capacitor Full scale ref., noise Filter C4207 Capacitor Local bypass for A/D Conv. R4211-R4213 Resistors Serial Buss Pull UP and Downs R4214 Resistor Board Identification Load J4201 2 × 15 PIN, Male Daughter to Main Bd. Bd. Mt Plug Connector R4201-R4203 Resistors Pull-downs Switch closure lines D4201-D4203 Diodes, Signal Reverse Drive protection for MPU 2. The Firmware [0088] The pre-programmed rules for the controller 26 (comprising the firmware) are contained in the EEPROM memory chip. The rules govern, e.g., the operation of the user interface, the generation of the stimulation timing and command signals by the supported function-spicific utilities, the interface with the various function-specific control signal devices (including wireless links), the special modulation of pulse outputs, and communication with external programming sources. The control algorithms expressing the rules can be realized as a “C” language program implemented using the MS WINDOWS™ application. [0089] The firmware, once embedded, can be reprogrammed or updated in various ways, including linkage (by cable or wireless infrared) of the controller 26 to an external computer with the appropriate software, or by the user using the keypad 34 on the controller 26 itself. [0090] Further details of these representative implementations of these functional blocks of the controller firmware will now be described. 3. The User Interface [0091] In the illustrated implementation (see FIG. 3A) the front shell 44 of the controller 26 presents the display 32 on which the various screens generated by the user interface are displayed. The user interface also displays on the screen 32 various graphic icons, e.g., a battery life icon 54 , a stimulation energy application icon 76 , and others (not shown), such an alarm or warning icon and a external computer connection icon. Associated audible signals can also be used to provide information regarding the status of these indications, e.g., low or discharged battery, errors, etc. [0092] The front shell 44 of the controller 26 also presents the keypad 34 , through which the user communicates with the interface. In the illustrated implementation (see FIG. 3A), six push buttons 56 to 66 are present. The push button 56 is used to turn the controller on. The button 56 also serves an enter key to progress from screen to screen of the interface. The push button 58 is used as to exit out of certain programming screens, as well as a control signal source in certain functions. The push buttons 60 and 62 are used to scroll up and scroll down the screens, to move through the menus generated by the user interface. The push bottons 64 and 66 are used to increment or decrement selections during certain functions. An audible signal or beep can be selectively generated upon pushing the buttons 56 to 66 . E. Task Selection Menu [0093] Upon power up, the firmware displays an appropriate welcome screen (not shown) and executes a main loop, which continues to runs in the background at prescribed time intervals (e.g., every 16 msec). The main loop self-test the microprocessor 36 for defective hardware or corruption of the flash memory contents. Errors noted by the main loop interrupt operation of the controller 26 and cause the user interface to display appropriate error icon and audible signal. [0094] Absent an error during start up, the user interface function displays a Task Selection Menu 68 (see FIG. 3A) on the display screen 32 . The Task Selection Menu 68 lists the specific therapeutic or prosthetic functions supported by the controller 26 . In the illustrated implementation, the listed functions are (i) The Finger-Grasp Function; (ii) the Standing Function; and (iii) the Bladder and Bowel Control Function, as already described. The user selects a function by scrolling (operating the scroll buttons 60 and 62 ) and pushing the enter button 56 . Upon selection, the firmware executes the function-specific processing utility dedicated to the selected function. [0095] By way of example, the details of the processing utility dedicated the finger-grasp function will be described. Similar interface and control features can be executed to carry out the other functions. [0096] In the illustrated implementation (see FIG. 6), the Opening Screen 70 for the finger-grasp function list four operational choices: Exercise; Function; Patterns; and Set Up. 1. Exercise [0097] By selecting Exercise (using the scroll bottons 60 and 62 and the enter button 56 ), the screen displays an Exercise Regime Screen 72 (see FIG. 7), which also shows a time delay before an exercise regime is automatically initiated by the firmware. Different exercise regimes (designated Exercise 1 , Exercise 2 , Exercise 3 , etc.) can be selected by the user by pressing the enter button 56 once within a predetermined short time interval (e.g., 3 seconds) after a given Exercise Regime Screen 72 is displayed. Typically, the timing parameters and exercise grasp patterns for each exercise regime have been preprogrammed into the firmware by a clinician, as will be described later. [0098] With the desired exercise regime selected, the user presses the enter button 56 or waits for the time delay to expire. The display 32 shows an Exercise Underway Screen 74 to indicates that stimulation is being applied to carry out the selected exercise regime. The Exercise Underway Screen 74 displays a Stimulation On Icon 76 , as well as the time remaining for the exercise session. As soon as the selected exercise regime is completed, the display 32 shows an Exercise Completed Screen 78 . [0099] After a prescribed time period of no further input (e.g., two minutes), the firmware turns the controller 26 off to conserve battery life. This automatic time-out feature is executed throughout the interface. 2. Patterns [0100] When Patterns is selected on the Opening Screen 70 (by use of the scroll buttons 60 and 62 and enter button 56 ) (see FIG. 8), the display 32 shows a Grasp Pattern Selection Menu 80 by which lateral and palmar grasp patterns can be selected. The Menu 80 lists “lateral” and “palmar” followed by numbers. The user scrolls using the buttons 60 and 62 to select either pattern. The user then increments or decrements using the buttons 64 and 66 to select the specific pattern by number. For example, there can be several lateral patterns (designated Lateral 1 , Lateral 2 , Lateral 3 , and Lateral Off) and several palmar patterns (designated Palmar 1 , Palmar 2 , Palmar 3 , and Palmar Off), which typically have been pre-programmed into the firmware by a clinician, as will be described later. When done choosing, the user selects the enter button 56 , which returns to the Opening Screen 70 for the finger-grasp function. 3. Function [0101] When a shoulder position sensor is coupled to the universal external controller 26 (designated as SW 1 in FIG. 9), selection of Function on the Opening Screen 70 allows the user to control the finger-grasp function using the external shoulder position sensor. Typically, the clinician will have previously preprogrammed the controller 26 so that either back and forth shoulder movements or up and down shoulder movements sensed by the shoulder position sensor will generate the appropriate proportional commands to open and close the grasp. The clinician may also have preprogrammed the controller so that quick movements of the shoulder position sensor will lock the grasp. Alternatively, the clinician may have preprogrammed the controller to lock the grasp in response to input from a remote lock switch (designated as SW 2 in FIG. 9) coupled to universal external controller 26 . The remote lock switch toggles the existing grasp pattern between a locked and unlocked position, and can be used by individuals who have difficulty with or do not want to use the shoulder jerk motion. [0102] With the Function selected, the user turns the shoulder position sensor on. The firmware responds to shoulder movement input in either elevation/depression or protraction/retraction to grade hand position and strength from opened to closed. Thus, for example, by retracting the shoulder, the hand opens, and by protracting the shoulder, the hand closes. [0103] In response to shoulder movement, the firmware turns the stimulation on to undertake the last selected lateral grasp pattern. The firmware executes a proportional control algorithm that, in response to the prescribed shoulder movement (e.g., protracting the shoulder), applies stimulation to progressively close the user's hand in the desired grasp pattern. Changing the prescribed shoulder movement (e.g., retracting the shoulder) changes the execution of the proportional control algorithm to apply stimulation to progressively open the hand. The hand can be thereby progressively opened or closed in this manner. Pressing a switch on the shoulder sensor will toggle between lateral and palmar grasp patterns [0104] As shown in FIG. 9, a Grasp-Function Status Screen 82 is displayed as the control algorithm is being executed. A graphical depiction on the Grasp-Function Status Screen 82 (which, in the illustrated embodiment, comprises a directional arrow and a bar chart) proportionally tracks the grasp position of the hand from open to closed, and vice versa. The Grasp-Function Status Screen 82 also displays the current grasp pattern. The Stimulation On icon 76 is also displayed. [0105] If so programmed, a small quick shoulder motion will lock the grasp in the then-existing position, and the Grasp-Function Status Screen will accordingly change to indicate the grasp is “locked.” With the grasp locked, the user is able to move the shoulder without altering the then-existing grasp pattern. When the user wants to regain control of the hand, a subsequently small quick shoulder motion will unlock the grasp, and the grasp function resumes according to the prescribed shoulder movement from the then-existing position. The Grasp-Function Status Screen 82 changes to indicate that the grasp is “unlocked” and the proportional direction display resumes. Alternatively, if so programmed, depressing a remote lock switch will cause the grasp to lock and unlock. [0106] Desirably, according to preprogrammed rules in the firmware, when the unlock command has been given, the grasp command enters a realignment state, during which the existing position of the grasp will not change until the user moves the shoulder back to the position where the lock command occurred. This keeps the user's hand from step-jumping opened or closed until the user is prepared to control it. Alternatively, the realignment state can be automatically implemented, during which, upon receiving an unlock command, the firmware aligns the grasp command range with the user's current shoulder position. The position of the command range can be automatically adjusted during proportional control, too. These options are selectable during programing of the firmware. [0107] Appropriate audio signals can be also generated by the controller to mark changes in the stimulated grasp pattern from open to close, locked and unlocked, lateral and palmar. [0108] Holding the enter button 56 for a predetermined time (e.g. 2 seconds) turns the controller 26 and the ongoing stimulation off. Holding the switch on the shoulder position sensor for a prescribed period will also turn the ongoing stimulation off. [0109] If a shoulder position sensor is not coupled to the universal external controller 26 , the user can subsequently control a selected grasp pattern by using the keypad 34 on the controller 26 itself. [0110] In a representative implementation, with the Opening Screen 70 for the finger-grasp function displayed, depressing the enter button 56 for a prescribed time period (e.g., 2 seconds) turns the stimulation on to undertake the last selected lateral grasp pattern. As FIG. 10 shows, the Grasp-Function Status Screen 82 is displayed, as previously described. The firmware executes a gated ramp control algorithm that, in response to pressing or holding the control button 58 , applies stimulation to progressively close the user's hand in the desired grasp pattern. Pressing the enter button 56 changes the execution of the gated ramp algorithm to apply stimulation to progressively open the hand. The hand can be progressively opened or closed in this manner. The graphical depiction on the Grasp-Function Display Screen 82 (i.e., in the illustrated embodiment, the directional arrow and a bar chart) proportionally tracks the grasp position of the hand from open to closed, and vice versa. Pressing the enter button 56 twice while executing a grasp function toggles between a selected lateral or palmar grasp pattern. The Grasp-Function Display Screen likewise displays the current grasp pattern and the Stimulation On Icon 76 . [0111] By releasing the enter button 56 as the hand is opening or closing, the gated ramp algorithm locks the hand at the then-existing grasp position, and the Grasp-Function Status Screen 82 accordingly indicates that the grasp is “locked.” When the user wants to regain control of the hand, a subsequently pressing the enter button 56 resumes the grasp function in the last selected direction from the last-existing position. Upon receiving a lock command, the gated ramp control algorithm maintains the grasp as the last-existing command level until it receives a further command from the keypad 34 to unlock the grasp pattern or to turn the controller 26 off. [0112] Holding the enter button 56 for a predetermined time (e.g. 2 seconds) turns the controller 26 and the stimulation off. 4. Setup [0113] The firmware can permit an individual user to program designated functions of the controller using the keypad 34 . The extent to which the firmware allows this will vary according to degree of freedom the manufacturer or clinician wants to provide an individual user. [0114] Selection of Setup in Opening Screen 70 (using the scroll buttons 60 and 62 and control button 58 ) permits this function. In one representative implementation, the firmware allows the user to customize the controller 26 by (i) selecting the grasp lock control input source; (ii) disabling sound that accompanies use of the keypad 34 or shoulder position sensor; (iii) or changing the volume of audible feedback. [0115] Selection of Setup displays a Selection Menu Screen 84 (see FIG. 11), where the permitted reprogramming selections are listed. By scrolling to the appropriate selection (using buttons 60 and 62 ), incrementing or decrementing the associated status selections (using buttons 64 and 66 ), and by selecting (by pressing the enter button 56 ), the various reprogramming selections can be accomplished. For example, the user can choose to lock the grasp using an external switch or by shoulder motion itself; or turn the keypad sound on or off; or turn the audible feedback for shoulder sensor movement on or off; or adjust audible feedback volume from medium or high. F. Interface with the Control Signal Devices [0116] The universal external controller 26 can accommodate input from a variety of external control sources, such as myoelectric surface electrodes, remote control switching devices, reed switches, and push buttons on the user interface panel of the universal external controller 26 itself. External control sources can be coupled to the universal external controller 26 by direct (i.e., cable) connection, or by wireless link (e.g., 900 MHz). G. Communication with External Programming Sources [0117] When the universal external controller 26 is not otherwise engaged in the execution of a functional task, the controller 26 can be linked to a remote computer 86 for programming by a clinician(see FIG. 12). [0118] The link can comprise a hardware interface, e.g., an interface module and serial cable to route and translate data between the remote computer 26 and universal external controller 26 . Alternatively, the firmware of the universal external controller 26 allows communication through an infrared link, thereby eliminating the need for an interface module, serial cable and any direct hardware connection. The infrared link simplifies communication and eliminates electrical safety concerns associated with direct electrical connection. [0119] The firmware establishes communication with the remote computer 86 , to identify and qualify incoming information received from the remote computer 86 . The interface desirably includes a Clinician Set Up Screen 88 (see FIG. 13), which is displayed upon pushing the control button 58 when in the Opening Menu 70 for a given selected function. The Clinician Set Up Screen 88 shows a Computer Link prompt, which can be selected by use of the buttons 64 and 66 and control button 58 to show a Computer Link Status Screen 90 . The Computer Link Status Screen 90 indicates “waiting” and then “talking” as the link between the universal external controller 26 and the remote computer 86 is established. [0120] In the illustrated implementation (see FIG. 12), the remote computer 86 desirably executes a programming system 92 , which can be used to control, monitor and program the universal external controller 26 in the selected function. The programming system 92 allows a clinician to customize the firmware residing in an individual universal external controller 26 according the specific needs of the user and the treatment goals of the clinician. The primary purpose of the programming system 92 is to adjust parameters and store the parameters affecting the selected function in the universal external controller 26 , which is used by the patient during daily operation. The system 92 also desirably provides an interface to display visual feedback to the clinician and user about the operation of the control algorithms and equipment associated with the controller 26 . [0121] In a representative implementation, when the finger-grasp function is selected, and the universal external controller 26 and remote computer 86 are linked, the programming system 92 can be run to assess the muscle recruitment patterns, set grasp stimulation patterns, adjust controller parameters, set exercise timing, and retrieve usage data resident in the firmware affecting the finger-grasp function. The programming system 92 enables inputs from the universal controller 26 to be monitored and stimulus outputs to be controlled in real time. The programming system 92 also allows operational parameters to be saved to an electronic patient file and downloaded to the universal external controller 26 . The universal external controller 26 can then be disconnected from the programming system, allowing portable operation, as already described. [0122] Desirably, the programming system 92 can be installed on a personal computer (e.g., a 233 MHZ Pentium II laptop with 800×600 resolution monitor) running Microsoft Windows™98 or higher. The programming system 92 desirably includes a clinician programming interface, which allows allows the clinician to observe, modify, and program the stimulus patterns, the shoulder position control characteristics, and the exercise sequences in an expeditious and user-friendly way. In a representative implementation, the clinician programming interface can be written in the Visual Basic 6 programming language for execution in the Windows environment. [0123] In the illustrated implementation (see FIG. 12), the system is composed of a generic module 94 including generic patient information and as well as one or more specific modules 96 for each of the function-specific tasks supported by the controller 26 (e.g., the finger-grasp function, the standing function, and the bladder and bowel control function). [0124] The generic patient information module 94 stores all general information about the patient using the particular universal external controller 26 . The information in this module 94 does not necessarily relate to any particular function-specific device, but includes, e.g., fields for entering personal information that the patient may prefer to keep confidential. [0125] The number and nature of the specific modules 96 will vary according to the number and nature of the function-specific tasks that the controller 26 supports. By way of example (see FIG. 12), for the finger-grasp function, there can be a system device information module 98 , an electrode profiling module 100 , a lateral and palmar grasp patterns programming module 102 , a shoulder position sensor programming module 104 , and an exercise programming module 106 . Appropriate counterpart modules can also provided for the other treatment functions supported by the controller 26 . [0126] For the finger-grasp function, the device information module 98 captures, stores, displays, and allows modification of information that relates to the components arranged to accomplish the finger-grasp function system, including surgical implantation procedures, device serial numbers, electrode mapping, and progress notes. For the finger-grasp function, the remaining modules 100 to 106 allow optimization and programming of functional features of the components. [0127] The electrode profiling module 100 aids the clinician in determining the stimulation thresholds and operational range of parameters for each electrode implanted on a muscle. This information determines system performance and configures electrodes for grasp programming. For example, for each electrode, the maximum force that can be obtained from the electrode during use can be determined, as can specific points of interest (POI) of the recruitment characteristics of each muscle. For each electrode/muscle, the threshold for recruitment and the maximum desired force is determined for each grasp pattern. Additional POI's can be denoted such as spillover to other muscles and other comments. [0128] The grasp programming module 102 provides a mechanism for the clinician to program, view, and modify grasp patterns. The grasp pattern coordinates the activity of the muscles implanted with electrodes to produce different functional grasp, e.g. lateral and palmar grasps. The main functions of the module 102 are to program, view, and modify the activation level of each electrode as a function of percent command. This module 102 provides templates and example grasps that the therapist can modify for the individual patient. The therapist can then test the pattern, compare to previous patterns, and modify the pattern before transferring them to the universal external controller 26 . [0129] The shoulder position sensor programming module 104 provides a mechanism for the therapist to program, view, and modify the shoulder position proportional control and lock parameters. The module 104 allows the therapist to determine the patient's range of shoulder motion, select control and locking directions, select stationary or mobile command, display visual feedback to aid the patient in understanding the operation of the shoulder controller, set the parameters for locking the grasp, test the shoulder position sensor settings, both with and without an active grasp, and compare the new settings with previous settings. [0130] The exercise programming module 106 enables the therapist to program, view, and modifying patient exercise routines. The main functions of this module 106 include setting exercise duration, setting the delay in starting the exercise, selecting the exercise patterns, and selecting specific exercise timing parameter. It also allows the therapist and user test the exercise patterns prior to programming. [0131] In the illustrated implementation, the Clinician Set Up Screen 88 (see FIG. 13) also includes a Coupling Power prompt. When selected (using the buttons 60 and 62 and the control button 58 ), a Coupling Power Select Screen 108 is displayed. The Screen 108 allows the clinician (using the increment/decrement keys 64 and 66 and control button 58 ) to select an appropriate couple power setting, from 1 (lowest) to 5 (highest). The clinician can thereby adjust the power output of the pulse transmitter 16 for the selected function. The controller 26 is thereby able to adjust to different different depths of implantation for the receiver/stimulator for a given function, which, in turn, dictate different radio frequency power levels to transcutaneously link the receiver/stimulator for that function to the associated pulse transmitter for that function. The clinician is thereby able to customize the controller 26 to optimize reliable coupling while maximizing battery life. [0132] In the illustrated implementation (see FIG. 13), the Clinician Set Up Screen 88 also includes a Device Status prompt. When selected (using the buttons 60 and 62 and control button 58 ), a Device Status Screen 110 is displayed. Information on the Device Status Screen 110 allows the clinician to assess the operating state of the controller 26 for monitoring and trouble shooting purposes. H. Power Conservation [0133] In addition to the allowing optimization of coupling power (as just described), the firmware also incorporates preprogrammed rules that promote other power conserving techniques aimed at prolonging battery life. In the illustrated embodiment, the power conserving techniques includes pulsed signal output (to the receiver/stimulator) and pulsed signal input (from the control signal source). 1. Pulsed Signal Output [0134] As previously described, under the control of the pre-programmed rules in the firmware of the microprocessor 36 , the universal external controller 26 governs the hand-grasp function by generating prescribed stimulus timing, command, and power signals based upon input received from the shoulder position sensing control signal source. The prescribed stimulus timing, command, and power signals are formatted for transmission by the function-specific pulse transmitter in the form of modulated radio frequency carrier wave pulses. By pulsing the output command signal for the hand-grasp function, the universal controller conserves power, to thereby conserve battery life. [0135] As shown in FIG. 14A, the output command signals are transmitted during successive frame intervals 114 . Each successive frame interval includes 114 an ON period 116 , during which radio frequency energy is generated to transmit the command signals to the function-specific pulse transmitter, and an OFF period 118 , during which no radio frequency energy (and thus no command signals) are being transmitted. The duration of the frame interval 114 can vary. In a representative embodiment, the ON periods 116 and OFF periods 118 begin on 1 msec boundaries, so that the frame interval 114 is an integer multiple of 1 msec. The frame rate is set to equal the stimulus frequency, which equals 1/Frame Interval. In a representative embodiment, the stimulus frequency is 6.78 MHz±5 KHz. [0136] Within each ON period 116 of a given frame interval 114 (see FIG. 14B), there is a power up phase 120 , followed by an output stimulus phase 122 , followed by a recharge phase 124 (to allow for radio frequency magnetic field decay). The command signals 126 are transmitted only during the output stimulus phase 122 . The command signals 126 are transmitted in channel groups 128 , with a channel 128 group dedicated to a given implanted electrode where stimulation is to be applied. Each channel group 128 includes a set amplitude command 130 and an set duration command 132 . The length of the output stimulus phase 122 will, of course, depend upon the number of channels receiving stimulation and the nature of the stimulation. When a channel has no command output (i.e., there are no set amplitude or duration commands for that channel), the next higher stimulation channel assumes its time slot. [0137] In the illustrated embodiment, all commands begin on 1 msec boundaries (as previously stated). Representative time periods for the phases are, for the power up phase 120 : 16 msec in duration if the OFF period 118 is more than 52 msec in duration, otherwise, 6 msec; for the output stimulus phase 122 : 2 times N msec in duration, where N is the number of channels being stimulated; and for the recharge phase 124 , 10 msec in duration. As frame rates increase, the OFF period 118 will become shorter until there is no OFF period 118 . [0138] Within each channel group 128 , the set amplitude command 130 and the set duration command 132 are arranged within a pulse window 134 (see FIGS. 14C and 14D). The initial period of the pulse window includes a coding window 136 . The preprogrammed rules of the firmware generate successive radio frequency pulses during which radio frequency energy is applied (RF ON) and during which radio frequency energy is not applied (RF OFF). In a representative embodiment, the total interval for a given RF ON and RF OFF sequence is 10 μsec (±1 μsec), and the RF ON interval within this period is 4 μsec (±1 μsec). Gaps 140 are formed between the RF ON and RF OFF periods, which in the representative embodiment last 6 μsec (±1 μsec). The pre-programmed rules of the firmware establish the set amplitude command and the set duration command depending upon the number and sequence of gaps 140 in the pulse window 134 . [0139] The coded correlation prescribed between the number and sequence of gaps 140 and the related commands can, of course, vary. In a representative implementation (see FIG. 14C), a succession of two to nine gaps 140 in the initial coding window 136 prescribe the channel for which a set duration command 132 is to be effective. Two to nine gaps 140 identify channels 1 to 8, respectively (i.e., two gaps means channel 1 , three gaps means channel 2 , and so on). In FIG. 14C, seven gaps identify a set duration command for channel 6 . [0140] As further shown in FIG. 14C, the succession of channel gaps 140 in the coding window 136 is followed by a gap 142 having a length (i.e., duration) which sets the actual duration of the stimulation pulse that is to be applied to the prescribed channel. The length of the gap 142 outside the coding window 136 can vary, e.g., between 1 μsec to 200 μsec. In FIG. 14C, the gap 142 outside the coding window 136 is shown to be 65 μsec, which specifies a stimulus duration of 65 μsec. [0141] In the representative implementation (see FIG. 14D),a succession of eleven gaps 140 in a successive coding window 136 prescribes the amplitude of the pulse that is to be applied to the earlier prescribed channel. As FIG. 14D shows, following the eleven gaps 140 in the coding window 136 is another succession of gaps 144 outside the coding window 136 , the number of which set the pulse amplitude. For example, in the representative implementation, eleven gaps 140 in the coding window 136 followed by one gap 144 sets an amplitude of 14 mA; eleven gaps 140 in the coding window 136 followed by two gaps 144 sets an amplitude of 8 mA; eleven gaps 140 in the coding window 136 followed by three gaps 144 sets an amplitude of 2 mA, and eleven gaps 140 in the coding window 136 followed by four gaps 144 sets an amplitude of 20 mA. In FIG. 14D, a pulse amplitude of 2 mA is set. [0142] In a representative embodiment, each pulse window 134 is assigned a duration of at least 410 μsec. Within the pulse window 134 , the initial coding window 136 is assigned a duration of 150 μsec (±5 μsec). 2. Pulsed Single Inputs [0143] The input from the shoulder position sensor can also be pulsed, to conserve power consumption. In the illustrated embodiment, as already explained, the power supply 236 on the auxiliary board 40 converts battery voltage to the 5 V excitation level for the shoulder position sensor. The 5 V output to the shoulder sensor is pulsed at a duty cycle of, e.g., {fraction (1/16)}. Thus, the input from the shoulder position sensor to the controller 26 is received in pulses. [0144] I. Therapetic Functional Neuromuscular Stimulation Using a Universal External Controller The firmware of the universal external controller 26 can be programmed for use in association with other components to perform other neuromuscular stimulation functions. For example, the universal external controller 26 can be used to provide therapeutic exercise and pain relief for stroke rehabilitation and surgical speciality applications, including shoulder subluxation, gait training, dysphagia, tenolysis, orthopedic shoulder, and arthroplasty. [0145] Details of the treatment of shoulder subluxation by neuromuscular stimulation are set forth in copending U.S. patent application Ser. No. 09/089,994, filed Jun. 3, 1998 and entitled “Percutaneous Intramuscular Stimulation System” and copending U.S. patent application Ser. No. ______, filed Jan. 6, 2001 and entitled “Treatment of Shoulder Dysfunction Using a Percutaneous Intramuscular Stimulation System,” both of which are incorporated herein by reference. II. Representative Uses of the Universal External Controller [0146] The universal external controller 26 as described herein incorporates several fundamental features that address convenience, flexibility, and ease of use. [0147] By way of example, these features include: [0148] (i) The controller 26 can be worn on the users body by virtue of it having a low weight and size. [0149] (ii) The user can be enabled to modify parameters, such as how to control the system, the type and degree of exercise they undertake, and the type and degree of stimulus parameters they use for their stimulation function. [0150] (iii) The utilization of cell phone battery technology makes the service, maintenance, and usage of the system more “consumer-like” and therefore easier to understand and use. [0151] (iv) The controller 26 isolates the user from ever having to connect the system directly to any source of power or communication link. The system uses the rechargeable battery as its sole power source and the infrared link as a communications port to a computer. [0152] (v) The controller 26 enables an extremely flexible control-input port that allows for, e.g.: [0153] 1. Wireless communication (900 mghz) [0154] 2. Proportional input signals (shoulder control) [0155] 3. Natural signals generated by the body (EMG, ENG, EEG) [0156] 4. A direct contact switch (on-off) [0157] (vi) The controller 26 can support simultaneous control of two independent RF based implantable pulse generators (e.g., motor-control, and/or bladder/bowel control, and/or erection control function). [0158] (vii) The controller 26 can communicate to any RF-based implantable pulse generators. Thus, the controller 26 can be easily integrated into an existing RF-based stimulation system. [0159] (viii) The controller 26 can be programmed by a host computer, or be programmed directly by the user or a trained technician, without the need of an external host computer. [0160] The following Examples are provided to exemplify the convenience, flexibility, and ease of use of a controller 26 that embodies features of the invention. EXAMPLE 1 Different Selectable Neuromuscular Functions [0161] It has already been explained how the controller 26 can enable individual selection of different, functional neuromuscular stimulation functions, e.g., the finger-grasp function, or the standing function, or the bladder and bowel control function. [0162] The controller 26 can also be configured to provide these and other different neuromuscular functions concurrently. For example, using the menu-driven interface of the controller 26 , as previously described, the user can select to implement a standing function concurrently with a bladder and bowel control function. In this arrangement, e.g., a user could affect concurrent neuromuscular stimulation to enable micturation while in a standing position. In the arrangement, the controller 26 receives control signals through one input to affect the operation of the standing function (e.g., a remote push-button control coupled to the input, or a push button programmed for this purpose on the user interface panel of the universal external controller 26 itself), while receiving other control signals through another input to affect operation of the bladder and bowel control function (e.g., another remote push-button control coupled to the other input, or another push button on the controller 26 programmed to accomplish this purpose). Concurrently, the controller 26 generates one stimulation output to the receiver/stimulator 18 ( 2 ) for the standing function, while generating another, different stimulation output to the receiver/stimulator 18 ( 3 ) for the bladder and bowel control function. In this arrangement, the controller 26 concurrently supports different control signal inputs and different stimulation outputs to different stimulation assemblies. [0163] The controller 26 can be further configured to concurrently provide an additional finger-grasp function, based upon control signal input received by the controller 26 from e.g., a shoulder position sensor, and a stimulation output generated by the controller 26 to the receiver/stimulator 18 ( 1 ) for the finger-grasp function. These concurrent, multiple stimulation functions make possible normal user control over the bladder and bowel function, while standing. Selection of the bladder and bowel control function concurrent with the selection of the finger-grasp function can also be accomplished, without selection of the standing function, to provide normal control over the bladder and bowel function while in a seated position. [0164] As another example, concurrent selection of the finger-grasp function and the standing function would enable the user to grasp objects while in a standing position. Concurrent selection of these two functions would also allow the user to ambulate while carrying an object grasped in the user's fingers. Again, normal control over these functions is thereby provided. EXAMPLE 2 Controller with Different Control Signal Sources [0165] As previously explained, the universal external controller 26 can accommodate input from a variety of external control sources, such as myoelectric surface electrodes, remote control switching devices, reed switches, and push buttons on the user interface panel of the universal external controller 26 itself. External control sources can be coupled to the universal external controller 26 by direct (i.e., cable) connection, or by wireless link (e.g., 900 MHz). These different control signal sources can be selected for operation concurrently to achieve different, concurrent stimulation functions (as the preceding Example 1 demonstrates). These different control sources can also achieve the same stimulation function based upon different source inputs. [0166] For example, the user can choose to affect the standing function, e.g., by operation of a remote push-button control, or a reed switch, or a push button programmed for this purpose on the universal external controller 26 itself. In addition, the user can also provide a designated care partner with a remote control switch to affect the standing function independently of the user, either by wireless transmission of a control signal or by a cable connection. Thus, for example, while the user holds of an ambulation assistance device, such as a walker, the care partner can remotely affect the standing function for the user, so that the user can be lifted to a standing position while the assistance device lends ancillary support and stability. Conversely, the care partner can remotely affect the termination of the standing function, so that the user can return to a seated position while the assistance device lends ancillary support and stability. [0167] Various features of the invention are set forth in the following claims.

The systems and methods provide effective neuromuscular stimulation to meet a host of different prosthetic or therapeutic objections. The systems and methods also provide convenience of operation, flexibility to meet different user-selected requirements, and transportability and ease of manipulation, that enhance the quality of life of the individual that requires chronic neuromuscular stimulation.