Patent Publication Number: US-2004053011-A1

Title: Document structure with circuit elements

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
     [0001] This application is a continuation-in-part of U.S. Ser. No. 08/794,120, filed Feb. 3, 1997, which was a continuation in part of U.S. Pat. No. 5,599,046, filed Jun. 22, 1994 and issued Feb. 4, 1997. 
    
    
     
       FIELD OF THE INVENTION  
       [0002] This invention relates to the filed of document structures and printing methods, and more particularly to document structures and methods of printing documents having machine readable security information and security features.  
       BACKGROUND OF THE INVENTION  
       [0003] It is often desirable to obtain information from documents in addition to the human readable information printed on the surface of the document. For instance, documents of many types are susceptible to tampering, alteration and counterfeiting. Lottery tickets for probability games are an example of a document which is particularly susceptible to tampering. A probability game lottery ticket normally has play areas, each containing play indicia covered by an opaque material, for example a latex material. To play the game, an individual scratches off the latex covering a specified number of the play areas to reveal the play indicia underneath. The player then determines if the combination of revealed play indicia is a winner such as the play indicia are all the same symbol or add up to a winning number.  
       [0004] Part of the popularity of such probability games is derived from the fact that each and every ticket is a potential winner. If a player has lost, that at least one winning combination is present. Consequently, this type of game is generally perceived by lottery players as being more legitimate than other types of instant lottery games.  
       [0005] The fact that every ticket is potentially a winner also invites players to tamper with the tickets. Because every ticket can win if the right play areas are selected, some players look for ways to determine the play indicia contained in every play area in order to identify the location of a winning combination. If the player can conceal the fact that he has seen the play indicia, the player subsequently can remove the latex covering from the play areas containing the winning combination and claim a prize.  
       [0006] One technique used to accomplish this result involves lifting the latex to look at the play indicia before gluing the latex back into place. Typically, probability game lottery tickets are validated by the visual observation of a human lottery agent. It can be difficult to visually detect this sort of tampering. Thus, probability game lottery tickets are particularly susceptible to fraudulent tampering and because no effective way of preventing or detecting such tampering has been developed, probability lottery games have not become commercially successful.  
       [0007] A second threat to the integrity of a document is the intentional alteration of its contents. For example, an individual may try to alter the information on a driver&#39;s license, contract, test answer form, invoice or inventory form. Such an alteration may involve the changing of a number in the document by removing the original number and inserting a new number. In the case of laminated documents, such as drivers licenses, the document can be delaminated and the driver&#39;s photograph can be replaced with the photograph of another person and the license relaminated. Such alterations can be very difficult to detect, especially if there are no other copies of the document.  
       [0008] A third type of problem posed in the document security context involves counterfeiting. Rather than altering an existing document, the counterfeiter actually creates a document and attempts to pass it off as being genuine. Thus, paper currency, tickets, tags, and labels are often counterfeited and proffered as the real thing. The magnitude of this problem has substantially increased with the advent of the color photo copier.  
       [0009] For example, the owner of a trademark might sell t-shirts bearing that trademark to increase the value of the shirt. In an attempt to thwart pirates, the trademark owner might also attach a identifying tag to the t-shirts. This makes it easier to determine whether a given t-shirt is genuine. In order to disguise the fact that t-shirts are counterfeits, a counterfeiter will reproduce not only the t-shirt&#39;s design, but also the tag. While being forced to create a similar looking tag will increase his costs, if the value of the trademark is sufficiently high, the counterfeiter will continue to attach a counterfeited tag.  
       [0010] There have been a number of techniques developed to improve the security of printed documents including the addition of magnetic materials to the document which are magnetically encoded with information that can be used to verify its authenticity. However, magnetically encoded information can in many instances be easily detected, read and altered and thus is not always suitable for verifying the integrity of a document and as such is generally not suitable for lottery tickets and probability tickets in particular. Another disadvantage of magnetically encoding information on a document, is that alterations to the magnetically encoded information are not generally detectable. Other methods for verifying the integrity of lottery tickets have been used such as inks that change color when tampered with but none of these methods have been sufficiently secure to permit the commercial sale of probability tickets.  
       [0011] There have also been a number of techniques developed for using electrical circuits in documents to represent information. See for example U.S. Pat. Nos. 3,699,311, 5,471,040 and 5,484,292. However, these documents suffer from a number of disadvantages including being expensive to manufacture and the delectability of the circuits in the document.  
       [0012] Hence, it is desirable to provide an improved system for obtaining information from documents to discourage tampering, alteration and counterfeiting.  
       SUMMARY OF THE INVENTION  
       [0013] It is therefore an object of the invention to provide a document structure and method of printing same that will provide for increased security as well as permitting information to be automatically read from the ticket.  
       [0014] Another object of the invention is to provide a lottery ticket structure and method of printing same that will result in a lottery ticket having sufficient security to be used as a probability ticket.  
       [0015] A further object of the invention is to provide a game ticket which includes a substrate, play indicia printed over the substrate and a scratch-off coating covering the play indicia which includes at least one electronic circuit element printed in conductive ink on the ticket. The electronic circuits can be printed over the play indicia and beneath the scratch-off coating. To improve security, the ticket includes an opaque blocking layer having a conductivity less than the circuit element. In this case, the game ticket can also include a seal coat applied over the play indicia and a release coat applied over the seal coat and below the electronic circuit elements to facilitate the removal of the electronic circuits when the scratch-off coating is removed or tampered with.  
       [0016] An additional object of the invention is to provide a game ticket that includes a substrate, an integrity electronic circuit or circuits printed on the substrate, a primer layer printed over the first electronic circuits, play indicia printed on the primer layer, seal and release coats printed over said play indicia and a scratch-off coating printed over the release coat. An printed indicia electronic circuit or circuits can be located between the seal and release coats over the play indica. One or more opaque blocking layers can be printed between the substrate and the scratch-off coating. Also, in the case where a bar code is printed on the lottery ticket, the integrity electronic circuit can be located underneath the bar code and extend to one or more of the play indicia.  
       [0017] Another object of the invention is to provide a game ticket having a substrate, a number of play indicia and a circuit element printed over the paper substrate having two capacitive pick-up areas connected by a resistive element where the resistive element is located under the play indicia. The resistive element can be printed with two layers of conductive ink. Also, the resistive element can be configured as a serpentine track.  
       [0018] Yet another object of the invention is to provide a document having a paper substrate, a number of play indicia, a printed circuit element having two capacitive pick-up areas connected by a resistive element. The resistive element can function as a stigmatization element. A conductive calibration line can also be printed on the document.  
       [0019] Still another object of the invention is to provide a data card having a substrate, a number of data areas each covered by a release coat, circuit elements printed over the release coats on the data areas and a scratch-off coating applied to the circuit elements.  
       [0020] A further object of the invention is to provide a laminated document having an information document and a circuit element located between the laminates. The document can include one or more of the circuit elements located between the information document and the laminates.  
       [0021] These and other objects are accomplished by the present invention which is directed to a method for printing a document. In one embodiment of the invention, the method includes the steps of (1) selecting a marking medium that has a pre-determined machine-readable characteristic, and (2) selecting a document substrate that is compatible with the pre-determined machine-readable characteristic of the selected marking medium. An information symbol is secured to the selected document substrate. A security layer which includes the selected marking medium is also affixed to the document substrate so that the security layer is in at least partial register with the information symbol. The method can further include the step of affixing a blocking layer to the document substrate in at least partial register with the information symbol. The blocking layer can be affixed to the document substrate so that blocking layer is intermediate the information symbol and the security layer or so that the security layer is intermediate the information symbol and the blocking layer.  
       [0022] In a second embodiment of the invention, the method includes the steps of (1) selecting a first marking medium that has a first pre-determined machine-readable characteristic; (2) selecting a second marking medium that has a second pre-determined machine-readable characteristic; and (3) selecting a document substrate which is compatible with both the first pre-determined machine-readable characteristic and the second pre-determined machine-readable characteristic. The document substrate is apportioned into at least a first portion and a second portion and a first information symbol is secured to the document substrate within the first portion. A first security layer that includes the first selected marking medium is also affixed to the first portion of the document substrate so that the first security layer is in at least partial register with the first information symbol. The method can also include the step of affixing a blocking layer to the document substrate in at least partial register with the first information symbol. The blocking layer can be affixed to the document substrate so that blocking layer is intermediate the first information symbol and the security layer or so that the security layer is intermediate the first information symbol and the blocking layer. The method can also include the step of affixing a second security layer that includes the second selected marking medium to the second portion of the document substrate so that the second security layer is in at least partial register with the second information symbol.  
       [0023] A third embodiment of the invention is directed to a method for forming a lottery ticket. The method includes the steps of (1) selecting a first marking medium that has a first pre-determined machine-readable characteristic; (2) selecting a second marking medium that has a second predetermined machine-readable characteristic; and (3) selecting a ticket substrate which is compatible with both the first pre-determined machine-readable characteristic and the second pre-determined machine-readable characteristic. The ticket substrate is apportioned into at least a first portion and a second portion. A play symbol is printed over the ticket substrate within the first portion and a bar code is printed over the ticket substrate within the second portion. A first security layer that includes the first marking medium is affixed to the first portion of the ticket substrate, in at least partial register with the play symbol. The first security layer, which is removable by a player from the ticket substrate, is affixed to the ticket substrate so that the play symbol is intermediate the ticket substrate and the first security layer. The method can also include the step of securing a second security layer which includes the second selected marking medium to the second portion of the ticket substrate, in at least partial register with the bar code.  
       [0024] Inks that can be printed with conventional printing methods, such as intaglio printing, screen printing, relief printing, planographic printing, letterpress printing, and flexographic printing, are especially useful as any of the selected marking media. The ink used is chosen for a particular machine-readable characteristic such as dry-state conductance, fluorescence, optical density, reflectance, and scattering. For example, an ink which has a known, measurable conductance in a dry-state can be used to print conductive layers on the document which serve as security layers. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0025]FIG. 1 is a plan drawing of a probability lottery ticket having an electrical signature according to the invention;  
     [0026]FIG. 2 is a plan drawing of the partial electrical circuit that provides the card in FIG. 1 its electrical signature;  
     [0027]FIG. 3 is a schematic representation of a gravure printing press used to print the ticket in FIG. 1;  
     [0028]FIG. 4 is a plan drawing of the first layer printed on the ticket in FIG. 1;  
     [0029]FIG. 5 is a plan drawing of the second layer printed on the ticket in FIG. 1;  
     [0030]FIG. 6 is a plan drawing of the third layer printed on the ticket in FIG. 1;  
     [0031]FIG. 7 is a plan drawing of customized graphics printed on the first portion of the ticket in FIG. 1;  
     [0032]FIG. 8 is a plan drawing showing the placement of the play indicia, validation number, inventory control number, and bar code which are printed on the ticket in FIG. 1;  
     [0033]FIG. 9 is a plan drawing of the back of the ticket in FIG. 1;  
     [0034]FIG. 10 is a plan drawing of the fourth layer printed on the ticket in FIG. 1;  
     [0035]FIG. 11 is a plan drawing of the fifth and sixth layers printed on the ticket in FIG. 1;  
     [0036]FIG. 12 is a plan drawing of the seventh layer printed on the lottery ticket on FIG. 1;  
     [0037]FIG. 13 is a plan drawing of the eighth layer printed on the lottery ticket in FIG. 1;  
     [0038]FIG. 14 is a perspective view of an electronic verification machine according to the invention;  
     [0039]FIG. 15 is a perspective view of an alternative embodiment of an electronic verification machine according to the invention;  
     [0040]FIG. 16 is a plan drawing of the user interface of the electronic verification machine in FIG. 14;  
     [0041]FIG. 17 is a block diagram of the major internal components of the electronic verification machine in FIG. 14;  
     [0042]FIG. 18 is a block diagram of the circuitry of the electronic verification machine in FIG. 14;  
     [0043]FIG. 19 is a plan drawing of the partial printed circuit used to determine the authenticity and integrity of the bar code of the ticket in FIG. 1;  
     [0044]FIG. 20 is a plan drawing of the partial printed circuit used to determine the authenticity and integrity of the play spot areas of the ticket in FIG. 1;  
     [0045]FIG. 21 is a plan drawing of another printed partial circuit which can be used to determine the authenticity and integrity of a probability lottery ticket;  
     [0046]FIG. 22 is a schematic circuit diagram of the completed circuit which is formed when the partial circuit in FIG. 20 is coupled to an electronic verification machine;  
     [0047]FIG. 23 is a plan drawing of a probability lottery ticket before the ticket is printed with yet another partial circuit which be used to determine the authenticity and integrity of the ticket;  
     [0048]FIG. 24 is a plan drawing of the release coat printed on the ticket in FIG. 23;  
     [0049]FIG. 25 is a plan drawing of the partial circuit used to determine the authenticity and integrity of the ticket in FIG. 23;  
     [0050]FIG. 26 is a plan drawing of the ticket in FIG. 23 in its final printed format;  
     [0051]FIG. 27 is a plan drawing of a second embodiment of the release coat printed on the ticket in FIG. 23;  
     [0052]FIG. 28 is a plan drawing of the circuit used to determine the authenticity and integrity of the ticket in FIG. 23;  
     [0053]FIG. 29 is a plan drawing of another circuit which can be used to determine the authenticity and integrity of a probability game ticket;  
     [0054]FIG. 30 is a plan drawing of another circuit which can be used to determine the authenticity and integrity of a probability game ticket;  
     [0055]FIG. 31 is a plan drawing of four printed resistors having different resistances;  
     [0056]FIG. 32 is a plan drawing of a partial printed circuit which includes a calibration line;  
     [0057]FIG. 33 is a partial plan drawing illustrating a ticket inductively coupled to an electronic verification machine;  
     [0058]FIG. 34 is a partial plan drawing of a conductor which can be printed on a ticket to provide an RF antenna;  
     [0059]FIG. 35 is a partial schematic circuit diagram of circuit which measures thermal variations to determine the authenticity and integrity of a ticket;  
     [0060]FIG. 36 is a plan drawing of a lottery ticket having sixteen play spot areas;  
     [0061]FIG. 37 is a plan drawing of the ticket in FIG. 36 having the play spot areas removed to reveal the underlying play indicia;  
     [0062]FIG. 38 is a block diagram of a second embodiment of an electronic verification machine;  
     [0063]FIG. 39 is a partial sectioned side view of the electronic verification machine of FIG. 38 illustrating a document transport mechanism;  
     [0064]FIG. 40 is a block diagram of a portion of the circuitry of the electronic verification machine of FIG. 38;  
     [0065]FIG. 41 is a schematic diagram of a position sensor array and buffer circuit that can be used with the circuit of FIG. 39;  
     [0066]FIG. 42 is a perspective view of an alternative position sensor array that can be used with the electronic verification machine of FIG. 38;  
     [0067]FIG. 43 is a plan view of a first lottery ticket suitable for use with the electronic verification machine of FIG. 38;  
     [0068]FIG. 44 is a game signature map representing the location of a scratch-off coating having conductive material on the lottery ticket of FIG. 43;  
     [0069]FIG. 45 is a data map representing the data out put of the electronic verification machine of FIG. 38 for the lottery ticket of FIG. 43;  
     [0070]FIG. 46 is an exploded perspective view of a pull-tab lottery ticket;  
     [0071]FIG. 47 is an illustrative top view of the pull-tab lottery ticket of FIG. 46 in conjunction with a signature map;  
     [0072]FIG. 48 is an illustrative top view of the pull-tab lottery ticket of FIG. 46 positioned below an electronic verification machine sensor array;  
     [0073]FIG. 49 is a plan drawing of a second embodiment of a probability ticket according to the invention;  
     [0074]FIG. 50 is a plan drawing of the circuit elements that form parts of the ticket shown in FIG. 49;  
     [0075]FIG. 51 is a schematic representation of a gravure printing press used to print the ticket in FIG. 49;  
     [0076]FIG. 52 is a plan drawing of a first blocking layer that is part of the ticket in FIG. 49;  
     [0077]FIG. 53 is a plan drawing of an alternative embodiment of the first blocking layer shown in FIG. 53;  
     [0078]FIG. 54 is a plan drawing of a second alternative embodiment of the first blocking layer shown in FIG. 53;  
     [0079]FIG. 55 is a plan drawing of one of the circuit elements in FIG. 49 as printed on the first blocking layer in FIG. 52;  
     [0080]FIG. 56 is a plan drawing of one of the circuit elements in FIG. 49 as printed on the first blocking layer in FIG. 53;  
     [0081]FIG. 57 is a plan drawing of one of the circuit elements in FIG. 49 as printed on the first blocking layer in FIG. 54;  
     [0082]FIG. 58 is a plan drawing of a masking layer that is apart of the ticket shown in FIG. 49;  
     [0083]FIG. 59 is a plan drawing of a primer layer that is apart of the ticket shown in FIG. 49;  
     [0084]FIG. 60 is a plan drawing of the display portion graphics that are part of the ticket shown in FIG. 49;  
     [0085]FIG. 61 is a plan drawing of play indicia which are part of the ticket shown in FIG. 49;  
     [0086]FIG. 62 is a plan drawing of the back of the ticket shown in FIG. 49;  
     [0087]FIG. 63 is a plan drawing of a seal coat which is part of the ticket shown in FIG. 49;  
     [0088]FIG. 64 is a plan drawing of a release coat which is part of the ticket shown in FIG. 49;  
     [0089]FIG. 65 is a plan drawing of an upper blocking layer that is part of the ticket shown in FIG. 49;  
     [0090]FIG. 66 is a plan drawing of an alternative embodiment of the upper blocking layer in FIG. 65;  
     [0091]FIG. 67 is a plan drawing a second alternative embodiment of the upper blocking layer in FIG. 65;  
     [0092]FIG. 68 is a plan drawing of some of the circuit elements shown in FIG. 50 as printed on the blocking layer shown in FIG. 65;  
     [0093]FIG. 69 is a plan drawing of some of the circuit elements shown in FIG. 50 as printed on the blocking layer shown in FIG. 66;  
     [0094]FIG. 70 is a plan drawing of some of the circuit elements shown in FIG. 50 as printed on the blocking layer shown in FIG. 67;  
     [0095]FIG. 71 is a plan drawing is a plan drawing of a scratch-off layer that is part of the ticket shown in FIG. 49;  
     [0096]FIG. 72 is a plan drawing of a combined seal-release coat that can be used on the ticket instead of the seal coat and the release coat that are shown in FIGS. 63 and 64, respectively;  
     [0097]FIG. 73 is an enlarged plan drawing of one of the circuit elements shown in FIG. 50 and illustrates a first printing defect;  
     [0098]FIG. 74 is a plan drawing of the circuit element in FIG. 72 and illustrates a second printing defect;  
     [0099]FIG. 75 is an enlarged plan drawing of one of the circuit elements in FIG. 50 and shows the configuration of the circuit element relative to a play indicia and a release coat portion or a seal-release coat portio;  
     [0100]FIG. 76 is a plan drawing of an alternative embodiment of the circuit element shown in FIG. 75;  
     [0101]FIG. 77 is a plan drawing of a marker card according to the invention;  
     [0102]FIG. 78 is a plan drawing of the circuit elements which are part of the marker card shown in FIG. 77;  
     [0103]FIG. 79 is a plan drawing is a plan drawing of the play indicia which are part of the marker card in FIG. 77;  
     [0104]FIG. 80 is a plan drawing of a seal coat which is part of the marker card in FIG. 77;  
     [0105]FIG. 81 is a plan drawing of a release coat that is part of the marker card in FIG. 77;  
     [0106]FIG. 82 is a plan drawing of an alternative embodiment of the release coat shown in FIG. 81;  
     [0107]FIG. 83 is a plan drawing seal-release coat that can be used instead of the seal coat and the release coat that are shown in FIGS. 80 and 81, respectively;  
     [0108]FIG. 84 is a plan drawing of an alternative embodiment of the seal-release coat in FIG. 83;  
     [0109]FIG. 85 is a plan drawing of the circuit elements in FIG. 78 as printed on the release coat shown in FIG. 81;  
     [0110]FIG. 86 is a plan drawing of the circuit elements in FIG. 78 as printed on the release coat shown in FIG. 82;  
     [0111]FIG. 87 is a plan drawing of the circuit elements in FIG. 78 as printed on the seal-release coat shown in FIG. 83;  
     [0112]FIG. 88 is a plan drawing of the circuit elements in FIG. 78 as printed on the seal-release coat shown in FIG. 84;  
     [0113]FIG. 89 is a plan drawing of a scratch-off layer that is part of the ticket shown in FIG. 77;  
     [0114]FIG. 90 is a plan drawing of a data card according to the invention;  
     [0115]FIG. 91 is a plan drawing of an alternative embodiment of the data card in FIG. 91;  
     [0116]FIG. 92 is a plan drawing a laminated document according to the invention;  
     [0117]FIG. 93 is a plan drawing of a lower laminate and a lower circuit element that is part of the laminated document in FIG. 92;  
     [0118]FIG. 94 is a plan drawing of an upper laminate and an upper circuit element that is part of the laminated document in FIG. 92;  
     [0119]FIG. 95 is a plan drawing of an information document that is part of the laminated document shown in FIG. 92;  
     [0120]FIG. 96 is a perspective view of a third electronic verification machine according to the invention;  
     [0121]FIG. 97 is a side perspective view of the electronic verification machine in FIG. 96 with the cover removed;  
     [0122]FIG. 98 is a partially cut-away exploded side perspective view of the electronic verification machine in FIG. 96;  
     [0123]FIG. 99 is a block diagram of the relationship among the major components of the electronic verification machine in FIG. 96;  
     [0124]FIG. 100 is a top plan view of a sensor head which forms a part of the electronic verification machine in FIG. 96;  
     [0125]FIG. 101 is a simplified partial circuit diagram of the capacitive coupling between the sensor head in FIG. 100 and a document being tested;  
     [0126]FIG. 102A is a plan view of a first printed layer pattern that can be used with the electronic verification machine in FIG. 96;  
     [0127]FIG. 102B is a conceptual representation of two capacitors which are formed when the sensor array of the electronic verification machine in FIG. 96 is capacitively coupled to a document which contains the first printed layer pattern shown in FIG. 102A;  
     [0128]FIG. 103A is a plan view of a second printed layer pattern that can be used with the electronic verification machine in FIG. 96;  
     [0129]FIG. 103B is a conceptual representation of two capacitors which are formed when the sensor array of the electronic verification machine in FIG. 96 is capacitively coupled to a document which contains the second printed layer pattern shown in FIG. 103A;  
     [0130]FIG. 104A is a plan view of a third printed layer pattern that can be used with the electronic verification machine in FIG. 96;  
     [0131]FIG. 104B is a conceptual representation of two capacitors which are formed when the sensor array of the electronic verification machine in FIG. 96 is capacitively coupled to a document which contains the third printed layer pattern shown in FIG. 104A;  
     [0132]FIG. 105 is a example of a printed circuit element that can be electronically altered by the electronic verification machine in FIG. 96, to stigmatize a document being tested;  
     [0133]FIG. 106 is a functional block diagram of a stigmatization circuit that can be used to stigmatize a document having the printed circuit element of the type shown FIG. 105; and  
     [0134]FIG. 107 is a conceptual diagram which illustrates the use of the electronic verification machine in FIG. 96 to measure the thickness of a document being tested. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0135] I. General Overview  
     [0136] The present invention is directed to a method and to an interrelated group of devices for determining the authenticity and integrity of a document and includes printing a portion of an electrical circuit on the document or applying a material having electrical conductive properties on the document. “Document”, as that term is used herein, is not limited to conventional printed papers but includes any type of flexible substrate as well as rigid substrates such as printed circuit boards. A document is authentic if it is not the product of counterfeiting. The integrity of a document relates to its current physical state as compared to its initial physical state and is affected by unauthorized modifications or attempted modifications of the document by, for example, subjecting the document to chemicals, heat, light, or pressure. The electrical characteristics of the printed circuit or the location of the conductive material provide the basis for determining both the authenticity and the integrity of the document. These characteristics can also be used to obtain data from the document.  
     [0137] A first method is to choose a predetermined, measurable electrical property, for example, a known resistance or capacitance, that will serve as the electrical signature of the document. Next, at least a portion of an electrical circuit is printed on the document using conductive or semi-conductive inks. The electrical circuit is designed so that when the circuit is completed, the circuit will generate an electrical signature that is substantially equal to a chosen predetermined electrical signature. Last, the circuit on the document is coupled to an electronic verification machine for determining the authenticity and integrity of the document by comparing the signal characteristics of the circuit on the document to the predetermined signature.  
     [0138] The electronic verification machine provides at least three functions. First, the electronic verification machine completes the circuit and provides a power source for exciting the circuit. Second, the electronic verification machine measures the resulting electrical signature of the document. And third, the electronic verification machine determines whether the measured electrical signature is substantially the same as the predetermined electrical signature. There are a number of ways in which the electronic verification machine can determine the authenticity and integrity of the document. The electronic verification machine can directly determine the authenticity and integrity of the document by using data directly available to the electronic verification machine. Alternatively, the electronic verification machine can indirectly determine the authenticity and integrity of a document by communicating the measured electrical signature to a remote computer which contains data related to the predetermined electrical signature for the document.  
     [0139] Determining the authenticity and integrity of the document is, in its simplest form, a logical progression. Generally, if an electrical signature can not be measured, the document is not authentic, is not in its original integral state, or both. On the other hand, if an electrical signature can be measured and the measured electrical signature is substantially the same as the predetermined electrical signature, the document can be assumed to be authentic and in its original integral state. If an electrical signature can be measured but is substantially different than the predetermined electrical signature, at the very least the document is not in its original integral state. This method will be explained in terms of a representative document which in this case is a probability game lottery ticket.  
     [0140] A second method is similar to the first method but involves the determination of the location of conductive materials on the document. This method will be explained in conjunction with the second embodiment of the electronic verification machine.  
     [0141] II. Probability Game Lottery Ticket Configuration.  
     [0142] The preferred embodiment of the invention is an electronic verification machine that can be used to determine the integrity and authenticity of a document, such as a probability game lottery ticket. Consequently, a brief overview of probability game lottery tickets is helpful. A probability game lottery ticket typically includes a group of play areas or play spots, each containing play indicia covered by an opaque material, usually a latex material. A player can win a prize if he removes the latex from a predetermined combination or combinations of play spots which define one or more winning redemption values. Generally the player is instructed to rub off only a specified number of play spots. Thus, a game may require a player to rub off three play spots. In this case, if the player rubs off more than three play spots, the ticket is void and player automatically loses. If the play indicia under the removed play spots match one of the predetermined combination(s), the player is eligible to redeem the ticket for a prize. On the other hand if the removed play spots do not match one of the predetermined combination(s), the redemption value of the ticket will be zero.  
     [0143]FIG. 1 illustrates the final printed format of a probability game ticket  50  according to one embodiment of the invention. The ticket  50  includes a card substrate  52  which is generally divided into two portions. A first portion  54 , the display portion, contains various types of printed information such as the name  56  of the probability game, information  58  related to the rules for playing the ticket, and customized art work  60 . A second portion, the playing field portion  62 , includes overprint areas  66 ,  68  and  76 . The square overprint areas  66  define a group of play spot areas  72 A-H of the ticket  50 . As shown in FIG. 1, the overprint area of one play spot area  72 A has been rubbed off the reveal the underlying play indicia  74 . The play indicia  74  can take any on a variety of forms including, as shown here, a dollar value. The play indicia  74  can also be formed from letters or words alone, numbers alone, or symbols alone, or any combination of letters, numbers, or symbols. Although not illustrated, it is to be understood that play indicia similar to play indicia  74  underlie each of the play spot areas  72 B-H.  
     [0144] The overprint area  76  defines the void-if-removed area of the ticket  50 . A validation number  78 , shown in FIG. 8, underlies the void-if-removed area defined by the overprint area  76 . The validation number  78  contains various types of security information including a portion that is usually algorithmically related to the pack number and ticket number for a particular ticket, such as the ticket  50 . The pack number identifies the pack from which the ticket  50  originates. The ticket number relates to the position of the ticket  50  within the pack. In addition as will be explained below, the validation number  78  can also include information related to the electrical signature(s) of the ticket  50 . The validation number  78  is useful for determining the authenticity and integrity of the ticket  50 , as explained in greater detail below, in Section V.  
     [0145] A bar code  80  is also printed within the playing field portion  62  of the ticket  50 . The bar code  80  can include information related to the validation number, the pack and ticket numbers for the ticket  50  and to the redemption values of various combinations of the play indicia  74  in each of the play spot areas  72 A-H. The bar code  80  can also be used to store information about the value of the play indicia  74  on the ticket  50 , as is explained in greater detail below, in Section V.  
     [0146]FIG. 2. illustrates a partial electrical circuit  81  which is interposed between the overprint areas  64 - 68  and the play indicia  74  of the ticket  50  shown in FIG. 1. In the preferred embodiment, the circuit  81  includes eight resistor tracks  82 - 96  which are divided into two columns of four resistor tracks each. Each resistor track  82 - 96  underlies the overprint areas  68  shown in FIG. 1 which define each of the play spot areas  72 A-H in FIG. 1. In addition, each resistor track  82 - 96  overlies a play indicia such as  74 . Eight conductive or capacitive pick-up areas  98 A-H are located around the periphery of the resistor tracks  82 - 96  and a central conductive track  100  is located between the two columns of resistor tracks  82 - 96 . The central conductive track  100  is connected to a conductive I-track shown at  102  which includes a terminal conductive bar  104  and a second conductive bar  106  parallel to and spaced apart from the terminal conductive bar  104 . A resistive track  107  connects the terminal conductive bar  104  to the second conductive bar  106 . In the final printed format, such as that shown in FIG. 1, the terminal conductive bar  104  underlies the bar code  80 .  
     [0147] Each resistor track  82 - 96  is electrically connected to the central conductive track  100  and to one of the conductive areas  98 A-H, for example, resistor track  82  is electrically connected to central conductive track  100  and to conductive area  98 A. The conductive areas  98 A-H and the central conductive track  100  are used to capacitively couple the ticket  50  to an electronic verification machine  108 , such as that illustrated in FIG. 14. In the preferred embodiment, each conductive area  98 A-H acts as a capacitor plate, the other capacitor plate being provided by the electronic verification machine  108 . In addition, the central conductive track  100  also acts as a capacitor plate, the second capacitor plate being provided by the electronic verification machine  108 . The capacitive coupling of the conductive areas  98 A-H and the central conductive track  100  to the electronic verification machine  108  completes the printed circuit  81  and permits the electronic verification machine  108  to excite the circuit and to measure the electrical signature or signatures of ticket  50 . Since the capacitive coupling of the conductive areas  98 A-H and the central conductive track  100  to the electronic verification machine  108  permits the electronic verification machine  108  to measure the electrical signature(s) of ticket  50 , areas  98 A-H and track  100  are also known as capacitive pick-up areas because through these areas the electronic verification machine  108  “picks-up” the electrical signature of ticket  50 .  
     [0148] Because each of the resistor tracks  82 - 96  is electrically connected to both the central conductive bar  100  and to one of the conductive areas  98 A-H, each of the resistor tracks  82 - 96  forms a complete circuit when the ticket  50  is coupled to the electronic verification device  108 . Thus each of the resistor tracks  82 - 96  has its own electrical signature equal to the printed resistance of the resistor track. As shown in FIG. 2, each of the four resistor tracks in the two columns has the same resistance. Since each of the resistor tracks  82 - 96  is electrically connected to its associated conductive area  98 A-H, the integrity of the eight circuits containing the eight resistor tracks  82 - 96  can be determined by reference to the specific conductive area  98 A-H used to measure the electrical signature. Alternatively, each resistive track may have a unique resistance. For example, the resistor track  82  can have a resistance of 100 KΩ, the resistor track  84  can have a resistance of 300 KΩ, the resistor track  86  can have a resistance of 500 KΩ, and the resistor track  88  can have a resistance of 2700 KΩ. Similarly, the resistor tracks  90 - 96  can have resistances of 100 KΩ, 300 KΩ, 500 KΩ, and 700 KΩ respectively. As is explained in greater detail in Sections III and IV.C.1., the magnitude of the resistance for a specific resistor track is a function of the type of ink used to print the resistor track, the length of the resistor track and the cross-sectional area, including the thickness, of the resistor track. Differences in the four resistances  82 - 88  or  90 - 96  in a given column of resistor tracks facilitate the determination of the authenticity and the integrity of the ticket  50  and more particularly can be used to determine which of the overprint areas  68  have been rubbed off.  
     [0149] Circuit  81 , as shown in FIG. 2, is actually a composite of several layers used to print ticket  50 . The following section describes in detail the sequence and relationship of the various layers used to print ticket  50 .  
     [0150] III. Printing The Electrical Signature  
     [0151] In the preferred embodiment, the circuit  81  is printed onto the ticket  50  preferable via a gravure printing process. The gravure printing process allows for the widest range of ink and coating formulations. The gravure printing process, however, is not the only printing process that can be used to print the circuits. Gravure is only one type of intaglio printing process. Other types of intaglio printing processes can be used as well. In addition, the circuit  81  can be printed via screen printing, relief printing, planographic printing, letterpress and flexographic printing. In the preferred embodiment, the ticket  50  is printed on a paper substrate. Paper substrates are preferred because they offer good insulation and absorbency. Alternatively, the ticket  50  could be printed on a plastic or a metal, such as an aluminum foil, substrate. If a foil substrate is used, portions of the foil can serve as the main conductor for the ticket  50 , while other portions of the ticket  50  are covered with an insulating layer.  
     [0152]FIG. 3 is a schematic diagram representing a gravure printing press  112  suitable for printing ticket  50 . The press  112  has fifteen gravure printing stations  114 - 142  and one ink jet station  144 . As is explained in more detail below, each of the press stations  114 - 142  prints one layer on the ticket  50  while the ink jet printer  144  prints the play indicia  74  and the bar code  80 .  
     [0153] Station  114  prints a first layer or surface  146  which is shown in FIG. 4. The first layer  146  is printed with a conductive-carbon based ink and forms a part of the circuit  81  shown in FIG. 2. The first layer  146  includes two portions the first of which is an I-track  148 . The I-track  148  includes the terminal conductive bar  104  and the resistive track  107  which form part of the I-track  102  illustrated in FIG. 2. A second conductive bar  150  of the I-track  148  underlies the second conductive bar  106  of the I-track  102  of FIG. 2. The second portion of the first layer  146  consists of a pair of rows of blocking cells  152 . Each of the blocking cells  152  is positioned to underlie one of the play indicia  74  which are subsequently printed on the ticket  50 .  
     [0154] The ink used to print the layer  146  should have a sheet resistivity below 2,700 Ω/□ preferably in the range of 1,000 Ω/□ to 1,300 Ω/□. In the ticket  50  shown in FIGS.  1 - 13 , the ink used to print the lower conductive layer  146  would most desirably have a sheet resistivity of 1,200 Ω/□. “Sheet resistivity” (ρs), as that term is used herein, is the bulk resistivity of the ink (ρ) divided by the thickness of the film of ink (t) printed on the ticket  50 .  
     ρ s=ρ/t.    
     [0155] Sheet resistivity (ρs) will typically be expressed in terms of ohms/square (Ω/□) . In practice, the sheet resistivity of an ink is determined by printing and measuring the resistance of a unit length and width.  
     [0156] The resistance (R) of a specific resistor in turn is a function of the bulk resistivity of the material and the dimensions of the resistor:  
       R=ρ ( l/tw )  
     [0157] where ρ is the bulk resistivity of the material used to make the resistor, l is the length of the resistor, t is the thickness of the resistor and w is the width of the resistor. Substituting the previous equation for sheet resistivity into the equation for resistance yields the following:  
       R=ρs ( l/w )  
     [0158] Thus, the resistance of a resistor printed with a conducting or semi-conducting ink is a function of the sheet resistivity of the ink, the length of the printed resistor, and the width of the printed resistor. For example, the resistance of a printed resistor with an ink having ρs=100 Ω/□ which is 0.120 inches (0.3048 cm) long and 0.040 inches (0.1016 cm) wide would be:  
       R=ρs ( l/w )=100 Ω/□(0.0120/0.040)=300 Ω.  
     [0159] The ink used to print the first layer  146  should also have very good adhesive properties so that the layer  146  adheres well to the ticket  50  and should have good abrasion resistance properties so that the layer  146  is not easily rubbed off the ticket  50 . A preferred formulation for the ink used to print the first layer  146  is given in Table 1.  
               TABLE 1                          Preferred Ink Formulation For Layer 1                             material   wt %                       Acrylic Resin   12-18%           Pentaerythritol ester of   2-6%           modified rosin           Conductive carbon   14-20%           Polyamine amide/acidic   0.3-1.0%           ester dispersant           2-ethyhexyl diphenyl phosphate   2-5%           plasticizer           Anhydrous ethyl alcohol   20-30%           Normal Propyl acetate   23-33%           50/50 mixed solvent, normal   5%           propyl acetate and ethyl           alcohol           950 varnish   5%                      
 
     [0160] The 950 varnish comprises 36.24% normal propyl acetate, 24.92% DM55 acrylic, 12.92% pentalyn  830 , 17.92% nitro varnish, and 3% santicizer  141 . The preferred formulation provides a film former, solvent based ink. Film formers are polymers capable of being plasticized to form a continuous and totally flexible ink. In the preferred formulation, the solvent evaporates from the printed surface during drying leaving a continuous, conductive dry ink film. Preferably, the conductive carbon will be about 2-20μ in size in this formulation.  
     [0161] The first layer  146  serves at least two purposes. First, the solid black nature of the blocking cells  152  of the first layer  146  serves to prevent unauthorized detection of the play indicia  74 , for example, by shining a bright light through the ticket  50 . Second, the I-track  148  can be used to protect the bar code  80  against unauthorized modifications, by providing an electrical signature for the bar code  80  which can be measured by the electronic verification machine  108 . It should be noted that in some cases, especially where the ticket  50  does not include the blocking cells  152 , it may be desirable to print an opaque blocking layer between the substrate  52  and the play indicia  74 .  
     [0162] Station  116  prints the second layer  156  which is shown in FIG. 5. The second layer  156  has two portions: an upper portion  156   a  and a lower portion  156   b . The upper portion  156   a  overlies all of the blocking cells  152  of the first layer  146  shown in FIG. 4. The lower portion  156   b  overlies the terminal conductive bar  104  and the resistive track  107  of the I-track  148  of the first layer  146 . The gap between the upper portion  156   a  and the lower portion  156   b  exposes the second conductive bar  150  of the I-track  148  of the first layer  146 . The second layer  156  acts as a blocking layer to prevent the first layer  146  from obscuring observation of the play indicia  74  when the ticket  50  is played. A suitable formulation for the second blocking layer  156  is disclosed in U.S. patent application Ser. No. 08/004,157 the entire disclosure of which is hereby incorporated by reference.  
     [0163] A third layer  158  is then printed by the printing station  118 . The placement of the third layer  158  is essentially coincident with the second layer  156 , as shown in FIG. 6. The third layer  158  also includes a upper portion  158   a  and a lower portion  158   b  separated by a gap which exposes the second conductive bar  150  of the I-track  148 . The third layer  158  is a primer layer which provides a suitable surface for printing the play indicia  74 . A suitable formulation for the third primer layer is disclosed in Walton, U.S. Pat. No. 4,726,608.  
     [0164] Printing stations  120 - 126  provide the features printed on the display portion  54  of the ticket  50 , as shown in FIG. 7. These printed features include the name  56  of the probability lottery game, information  58  related to the rules for playing the game, and customized art work  60 . Because 4 different printing stations  120 - 126  are used to print these features, as many as four different colors of ink can be used to print process colors.  
     [0165] The ink jet printer  144  prints the play indicia  74  on a portion of the third layer  158 , as shown in FIG. 8. In the preferred embodiment, there are two columns of play indicia  74 , each of which contains four separate play indicia  74 . The two rows of play indicia  74  are positioned so that each separate play indicia  74  overlies one of the blocking cells  152  of the first layer  146  shown in FIG. 4. The ink jet printer  144  also prints the inventory control number  70 , the validation number  78 , and the bar code  80  on the ticket  50 . In the preferred embodiment, the inventory control number  70 , the play indicia  74 , the validation number  78 , and the bar code  80  are printed with a water-based dye.  
     [0166] Printing station  128  prints the back  157  of the ticket  50  as shown in FIG. 9. The back  157  may include additional information  159  related to the rules for playing the ticket  50 .  
     [0167] The print station  130  prints a fourth layer  160  on the ticket  50 . The fourth layer  160  is indicated by the shaded portions in FIG. 10. The fourth layer covers the upper and lower portions  158   a ,  158   b  of the third layer  158  shown in FIG. 7, and also covers the play indicia  74 , the inventory control number  70 , the validation number  78 , and the bar code  80 . In the same manner as the second and third layers  156  and  158 , the fourth layer does not cover the second conductive bar  150  of the I-track  148 . The fourth layer  160  is a seal coat which protects the inventory control number  70 , play indicia  74 , the validation number  78 , and the bar code  80  from abrasion and from liquids in which the play indicia  74 , the validation number  78 , and the bar code  80  are soluble. Suitable materials for this purpose include various polymer materials such as acrylics, polyester urethane, epoxy acrylate, and vinyl polymer. A suitable formulation for the third primer layer  158  of FIG. 6 is disclosed in Walton, U.S. Pat. No. 4,726,608.  
     [0168] The print stations  132  and  134  print a fifth and a sixth layer  162  on the ticket  50 . As shown in FIG. 11, the fifth and sixth layers  162  are printed as discrete sections which overlie the play indicia  74  and the validation number  78 . The fifth and sixth layers  162  are indicated by the shaded areas overlying the play indicia  74  and the validation number  78 . The fifth and sixth layers  162  are both substantially transparent release coats which allow the play indica  74  to be viewed by the player and at the same time permit an easy removal of subsequent layers by, for example, rubbing the ticket  50  with a fingernail. The same release coat formula on may be used to print both the fifth and sixth layers  162 . A suitable formulation for the third layer is disclosed in Walton, U.S. Pat. No. 4,726,608. Also, in some cases it may be desirable to use an ultraviolet curable seal-release coat in place of the release coats  162 . Such seal-release coats are well known in the art.  
     [0169] The print station  136  prints a seventh layer  164  which comprises the remainder of the electrical circuit  81  shown in FIG. 2 which is printed on the ticket  50 . As illustrated in FIG. 12, the seventh layer  164  is a patterned layer which includes the resistor tracks  82 - 96  and the conductive areas  98 A-H. The seventh layer  164  also includes the conductive bar  106  of the I-track  102  shown in FIG. 2. As explained earlier, the resistor tracks  82 - 96  are connected to the conductive areas  98 A-H. The resistor tracks  82 - 96 , as printed thus have electrical continuity with the conductive areas  98 A-H and conductive track  100 .  
     [0170] The relationship between the first layer  146  and the seventh layer  164  is better understood with reference to FIGS. 19 and 20 which are respectively plan drawings of the first layer  146  and of the seventh layer  164  alone. As noted earlier, the first layer  146 , shown by itself in FIG. 19, consists of the blocking cells  152  and the I-track  148 . The I-track  148  includes the terminal conductive bar  104  and the resistive bar  107 . The seventh layer  164 , shown by itself in FIG. 20, consists of the resistive tracks  82 - 96 , the conductive areas  98 A-H, the central conductive track  100  and the conductive bar  106 . The seventh layer  164  is positioned on the ticket  50  so that the conductive bar  106  of the seventh layer overlies the conductive bar  150  of the first layer  146  to form the partial circuit  81  as illustrated in FIG. 2. The overlying relationship of conductive bars  106  and  150  ensures electrical continuity between the first layer  146  and the seventh layer  164 .  
     [0171] It is desirable that the ink used to print the seventh layer  164  have a sheet resistivity at least in the range of 300 Ω/□ to 600 Ω/□ and preferably, the sheet resistivity should be below 300 Ω/□. Several parameters can be varied to reduce the sheet resistivity of an ink. For example, the shape and size of the conductive particles affects the sheet resistivity of the ink. In addition, metal pigments tend to reduce the sheet resistivity as does a high pigment to binder ratio. However, both metal pigment and a high pigment to binder ratio tend to reduce the graphic adhesiveness of the ink. Unlike the ink used to print the first layer  146 , the ink used to print the seventh layer  164  need not have exceptional adhesive properties because the seventh layer  164  or portions thereof are designed to be removed to reveal the play indicia  74  when the ticket  50  is played. Consequently, the ink used to print the seventh layer  164  on the ticket  50 , or circuits on other types of documents where the adhesive qualities of the ink are not a major consideration, can include metal particles and can have a relatively high pigment to binder ratio. The use of metal particles in place of or in addition to carbon particles can substantiality increase the conductivity of the ink.  
     [0172] A preferred ink formulation for the seventh layer  164  is given in Table 2.  
               TABLE 2                          Preferred Conductive Ink Formulation For       Layer 7                             material   wt %                       Acrylic resin   10-15%           Pentaerythritol ester of   1-5%           modified rosin           conductive carbon    5-15%           silver plated copper   10-25%           particles (5-10μ)           polyamine amide/acid   0.25-0.75%           ester dispersant           anhydrous ethyl alcohol   25-35%           normal propyl acetate   28-38%                      
 
     [0173] Although the preferred metal particles are sliver plated copper particles, other conductive metal particles such as aluminum, brass, nickel, iron and iron oxide particles can be used as well. However, it should be noted that nickel may not be suitable for use in certain types of documents since it can be toxic if ingested. Also, in addition to sliver, the metal particles can be plated with gold or tin.  
     [0174] An eighth layer  168 , preferably a scratch-off latex material, is applied at printing station  138 . As shown in FIG. 13, the eighth layer  168  covers most of the playing field portion  62  of the ticket  50 . The eighth layer  168  does not cover the inventory control number  70  or the bar code  80 . The eight layer  168  does, however, overlie the conductive bar  102  of the seventh layer  164 . The final printing stations  138 ,  140 , and  142  apply overprint graphics such as overprint areas  66 ,  68 , and  76  illustrated in FIG. 1. The square overprint areas  68  serve to visually identify the individual play spot areas  72 A-H and the overprint area  76 , which overlies the validation number  78 , is printed with the instruction “void if removed.” 
     [0175] IV. Measuring The Printed Electrical Signature  
     [0176] A. An Electronic verification Machine  
     [0177] As stated earlier, the circuit  81  on the ticket  50  is completed when the ticket  50  is capacitively coupled to the electronic validation or verification machine  108  which then can measure the electrical signature of the circuit elements such as resistors  82 - 96  on the ticket  50 . FIG. 14 is a stylized perspective view of an exterior of the electronic verification machine  108 . Although the exact configuration of the exterior of the electronic verification machine  108  can vary, the exterior of the electronic verification machine  108  has three features: a results indicator  174 , a ticket interface  176 , and a user interface  178 . As shown in FIG. 14, the results indicator  174  of the electronic verification machine  108  is a display panel  180 . The display panel  180  can display the results of a ticket validation operation and can also display the results of verification testing, including tests of the authenticity and integrity of the ticket  50 . The display panel  180  can also display instructions, such as “Insert Ticket”, concerning the use of the electronic verification machine  108 . In place of or in combination with the display panel  180 , the electronic verification machine  108  can communicate with a printer  181  shown in FIG. 17 which can display the results of the ticket validation operation and verification testing as well. The user interface  178  can be a keyboard which the player or an agent can use to manually enter data from the ticket into the electronic verification machine.  
     [0178] A ticket interface  176  of the electronic verification machine  108  includes a ticket slot  182  into which the ticket  50  can be inserted. When the ticket  50  is properly inserted into the ticket slot  182 , the conductive areas  98 A-H,  100 , and  106  are aligned with an array of capacitor plates  226 A-H,  228  and  230 , as shown in FIG. 18, located within the electronic verification machine  108 , to complete the partial circuit  81  printed on the ticket  50 . In addition, the bar code  80  is aligned with a bar code reader  210  (not shown) located within the electronic verification machine  108 .  
     [0179]FIG. 15 is a stylized plan drawing of an alternative embodiment of an electronic verification machine  183  having a different type of ticket interface  177 . In this embodiment the electronic verification machine  183  has a hinged lid  184  which can be raised to expose the ticket interface  177  which includes a ticket recess  186 . Within the ticket recess  186  is a sensor area  188  containing an array of capacitor plates (not shown) which align with the capacitor areas  98 A-H,  100 , and  106  on the ticket  50 . The ticket recess  186  also includes a bar code reader area  190 . The ticket  50  is placed within the ticket recess  186  such that the bar code  80  can be read through reader area  190  by a bar code reader  210  located within the electronic verification machine  183  as illustrated in FIG. 17. The electronic verification machine  183  can also have a second sensor area  192  also containing capacitor plates (not shown) which align with the conductive areas  98 A-H,  100 , and  106  on ticket  50 .  
     [0180]FIG. 16 is a plan view of the preferred embodiment of the user interface keyboard  178 . The user interface  178  includes a numeric key pad  196  and a set of operation keys  198 - 204 . The operation key  200  is used to input the validation number  78  of the ticket  50  into the electronic verification machine  108  and the operation key  198  is used to manually input the bar code  80  of the ticket  50  into the electronic verification machine  108 . Keying in of the bar code  80  may be necessary if the bar code reader  210  is not able to read the bar code because, for example, the bar code  80  is damaged or perhaps has been tampered with.  
     [0181]FIG. 17 is a sectioned side view which includes a block diagram of the major internal components of the electronic verification machine  108 . The electronic verification machine includes the bar code reader  210 , and a ticket sensor  212 . The ticket sensor  212  senses when the ticket  50  has been properly inserted so that the bar code  80  can be read by the bar code reader  210 . When the ticket is properly inserted the conductive areas  98 A-H,  100 , and  106  of the ticket  50  are aligned with a pair of sensor plates, indicated at  214  and  216 , which include an array of copper capacitor plates  226 A-H,  228  and  230 , shown in FIG. 18, positioned in a configuration which mirrors that of the conductive or capacitor areas  98 A-H,  100 , and  106  of the ticket  50 . The sensor plates  214 ,  216  are part of a sensor head  218  which contains a set of excitation and detection circuitry for the electronic verification machine  108 . The electronic verification machine  108  also includes a processor board  220 , including a microprocessor and memory, and a communications interface  222 .  
     [0182] The excitation and detection circuitry of the sensor head  218  includes a microcontroller  224  with associated memory as shown in FIG. 18. The microcontroller  224  provides the necessary logic to control the electronic verification machine  108  and performs various tasks including controlling the communications interface  222 , the user interface  178 , and the bar code reader  210 . The microcontroller  224  also processes the measured electrical signature of the circuit elements  82 - 96  on the ticket  50  that can be used to determine the authenticity and integrity of the ticket  50 . Because the microcontroller  224  requires relatively little processing power, a single, self-contained IC can be used to provide inexpensive processing. Examples of acceptable chips include the Motorola 68HC711E9 and the Intel MCS®-51 Series microcontrollers. Each of these chips includes a Random Access Memory (“RAM”) and a Programmable Read Only Memory (“PROM”) and an Analog to Digital converter (“A/D”).  
     [0183] As is explained in greater detail below, in Section V., the bar code  80  can include information regarding the value of the play indicia  74  of the ticket  50 . The bar code reader  210  communicates directly with the microcontroller  224  via an ANSI standard interface, for example, UART. In the preferred embodiment, the bar code reader  210  is a laser scanner.  
     [0184] The communications interface  222  generally is a serial digital interface which may be a driver IC or a modem chip set. As is explained in more detail in Section V. below, the serial digital interface  222  allows the electronic verification machine  108  to communicate with a central host computer  223  when necessary to determine the authenticity or integrity of the ticket  50 . In the preferred embodiment, a non-standard interface or a low-level encryption is included in the design of the serial digital interface  222  in order to enhance the security of communications between the electronic verification machine  108  and the central computer  223 .  
     [0185] In operation, the excitation and detection circuitry of the sensor head  218  is capacitively coupled with the partial circuit  81  printed on the ticket  50  to complete the circuit  81 . Thus, a complete circuit  225  including the partial circuit  81  on the ticket  50 , as shown in FIG. 21, is completed  81  when the ticket  50  is placed within the ticket slot  182  in the sensor head  218 . It should be noted that the excitation and detection circuitry can also be coupled to the ticket  50  by various other methods including: direct coupling, inductive coupling, radio frequency coupling and optical coupling, as described below in Section IV.E.  
     [0186] In the preferred embodiment, the sensor head  218  of the electronic verification machine  108  is capacitively coupled to the circuit  81  on the ticket  50  to complete the circuit  81 . A block circuit diagram of the completed circuit  225  is shown in FIG. 21. As noted earlier, the conductive areas  98 A-H, the central conductive track  100 , and the conductive bar  106  function as capacitor plates. The sensor head  218  includes an array of the capacitive coupler plates  226 A-H,  228  and  230 , arranged in the same configuration as the conductive areas  98 A-H,  100  and  106 . When the ticket  50  is placed in the ticket slot  182 , the capacitor plates  226 A-H are aligned with the conductive areas  98 A-H, the central conductive track  100 , and the conductive bar  106  to form capacitors having an air gap dielectric. Alternatively, the capacitive couplers  226 A-H,  228  and  230  could be arranged within the electronic verification machine  108  so that the capacitor plates  226 A-H,  228  and  230  are positioned on the side of the ticket  50  opposite the conductive areas  98 A-H,  100  and  106 . In this configuration, the capacitors formed by coupling the capacitive couplers  226 A-H,  228  and  230  to the conductive areas  98 A-H,  100  and  106  would have a dielectric contributed both by the air gap and by the ticket substrate and printed layers located between the conductive areas  98 A-H,  100 , and  106  and the capacitor plates  226 A-H,  228  and  230 .  
     [0187] As noted earlier, each of the resistor tracks  82 - 96  is capacitively coupled in series to one of the capacitor plates  226 A-H in the sensor head  218  via one of the conductive areas  98 A-H. Similarly, a capacitor is formed by the capacitor plate  230  and the central conductive track  100 . In addition, the bar code resistor track  107  is connected in series with the capacitor formed by the capacitor plate  228  in the sensor head  218  and the conductive bars  106  and  150  and to the capacitor formed by the conductive track  104  and the capacitor plate  228 .  
     [0188] The capacitor plates  226 A-H and  228  are connected to a pair of buffer amplifiers  232  and  236 . The main buffer amplifier  236  supplies a signal to an integrator  238  in the electronic verification machine  108  which in turn supplies a signal to the microcontroller  224 . The secondary buffer amplifier  232  provides a feed back loop to the capacitor plates  226 A-H and  228  and hence the conductive areas  98 A-H. The resistor tracks which are not currently being tested by the electronic verification machine  108  can produce stray capacitance which would interfere with the measured detection signal. To overcome this effect, the secondary buffer amplifier  232  applies the buffered detection signal to the resistor tracks which are not being tested, such as tracks  82 - 86 ,  90 - 96 , and  107 , to cancel out the effect of the stray capacitances.  
     [0189] The microcontroller  224  is also connected to a digital to analog (“D/A”) converter  240  which supplies a signal to a voltage controlled oscillator (“VCO”)  242 . Because of the size constraints of a typical probability game ticket, such as ticket  50 , the capacitance formed by coupling the individual resistor tracks, such as resistor track  88 , to the excitation and detection circuitry is small. For example, a capacitor including a conductive track printed with the ink formulation described in Table 2 and having an area of 0.201869 inches 2  would have a capacitance of approximately 9 pF. Consequently, the excitation and detection circuitry includes an inductor  244  to oppose the effect of the capacitive impedance resulting from the small capacitance provided by coupling the capacitive pick-up areas  98 A- 98 H and  104  to the electronic verification machine  108 . The output from the VCO  242  is routed through the inductor  224  and applied to the central conductive track  100  via the excitation coupler  230 .  
     [0190] When the ticket  50  is inserted into the electronic verification machine  108  and the microcontroller  224  is activated, the electronic verification machine  108  begins a discreet verification process for each resistor track  82 - 96  and  107 . The microcontroller  224  steps an 8-bit output bus  245 , which controls the D/A converter  240 , from a value of 255 to zero. The DC output voltage from the D/A  240  is then applied to the VCO  242  for conversion to frequency. Thus, the microcontroller  224  produces a stepped series of decreasing excitation frequencies. These stepped excitation frequencies are routed though the inductor  244  and applied to the central conductive track  100  of the ticket  50  via the excitation coupler  230 . The excitation signal from the VCO  242  is ultimately applied to each of the eight resistor tracks  82 - 96  and the bar code resistor track  107 . The microcontroller  224  selects an individual resistor track, such as resistor track  88 , through solid state switches (not shown) and routes the capacitively coupled detection signal to the dual buffer amplifiers  232  and  236 . The main buffer amplifier  236  supplies a buffered voltage to the integrator  238  which converts the AC detection signal to a DC detection signal and applies this DC detection signal to the analog to digital input of the microcontroller  224  for processing.  
     [0191] In this embodiment, the electronic verification machine  108  uses a iterative resonance seeking algorithm to determine the measured electrical signature for each of the resistor tracks  82 - 96  and  107 . Two registers (not shown), the resonance register and the temporary register, in the microcontroller  224  are used to store successive values of the detection signal. The detection signal is the signal produced when any of the resistor tracks, such as resistor track  88 , is coupled to the electronic verification machine  108  and receives the excitation signal via the central conductive bar  100 . The contents of both the resonance and temporary registers are initially set to zero.  
     [0192] The amplitude of the detection signal is ultimately converted to an eight-bit binary value via the integrator  238  and the A/D input of the microcontroller  224 . The binary converted detection signal is then stored in the temporary register of the microcontroller  240  and the microcontroller  240  then compares the contents of the two registers. If the contents of the temporary register is less than the contents of the resonance register, the resonance register contains the binary converted equivalent of the amplitude corresponding to the resonance frequency of the resistor track being tested, such as track  88 . Consequently, the frequency of the excitation signal and the contents of the resonance register are output to the processor  220  and in certain cases to the communication interface  222  which includes a UART serial digital port. The output of the communication interface  222  which represents the electrical signature of the resistor track being tested can be transmitted to the central computer  223  or to a lottery terminal (not shown).  
     [0193] If the resonance frequency of the resistor track, such as track  88 , is not detected, the above excitation and detection process is repeated. First, the contents of the temporary register are stored in the resonance register. Thereafter, the 8-bit output bus, which controls the D/A converter  240 , is decremented to produce an excitation signal from the VCO  242  having a lower frequency than the previously applied excitation signal. The new excitation signal is applied to the ticket via the conductive track  100  and the new detection signal is compared, as previously described, with the contents of the resonance register. This excitation and detection process is repeated for each resistor track  82 - 96  and  107  until the detection signal corresponding to that associated with the resonance frequency of the resistor track being tested is determined.  
     [0194] B. Candidate Circuits For Providing The Electrical Signature  
     [0195] 1. The T-Square Circuit.  
     [0196] Several different types of circuit configurations can be printed on the ticket  50  to provide a measurable electrical signature. In the preferred embodiment, the printed circuit configuration  81 , termed a T-square circuit, is illustrated in FIG. 2. As noted earlier, each of the resistor tracks  82 - 96  is electrically connected to one of the conductive areas  98 A-H and to the central conductive track  100 . FIG. 20 is a plan drawing of the partial printed circuit used to determine the authenticity and integrity of the play spot areas  72 A-H and illustrates the resistor tracks  82 - 96  connected to the conductive areas  98 A-H and the central conductive track  100 . In addition, the bar code resistor track  107  is electrically connected to the conductive bars  104  and  106 . FIG. 19 is a plan drawing of the partial printed circuit used to determine the authenticity and integrity of the bar code  80  and illustrates the bar code resistive track  107  connected to the conductive areas  104  and  150 . As noted earlier, the first layer  146  printed on the ticket  50  includes the bar code resistor track  107  and the conductive areas  150  and  104 . Successive layers, up to and including the sixth layer  162 , do not overlie the conductive area  150  thus leaving the conductive area  150  exposed. The seventh layer  166  consists of the partial printed circuit used to determine the authenticity and integrity of the play spot areas  72 A-H, as shown in FIG. 20. The conductive bar  106  of the seventh layer  164  immediately overlies the conductive bar  150  of the first layer  146 . Consequently, the partial circuit including circuit elements  82 - 96  and  98 A- 98 H for the play spot areas  72 A-H, shown in FIG. 20, and the partial circuit for the bar code  80 , shown in FIG. 19, are electrically connected via the conductive bars  106  and  150 . Thus, when the ticket  50  is coupled to the electronic verification machine  108 , the excitation signal applied to the ticket  50  via the central conductive track  100  is also transmitted to the bar code resistive track  107  via the conductive bars  106  and  150 . Therefore, the completed circuit  225  which is formed when the ticket  50  is capacitively coupled to the sensor head  218  via the conductive areas  98 A-H,  100 ,  104 , and  106  is actually nine different, separate circuits, one for each of the resistor tracks  82 - 96  and one for the bar code resistor track  107 .  
     [0197] As is explained in Section V. below, the electronic verification device  108  tests the integrity of a specific resistor track, such as resistor track  88 , by comparing the measured resistance to the resistance which should result from the undisturbed configuration of the resistor track as originally printed, that is, the predetermined electrical signature of the resistor track. If the play spot area overlying the resistor track, such as track  88 , has not been altered, for example, rubbed off or lifted to reveal the underlying play indicia, the resistance measured by the electronic verification machine  108  will be substantially the same as the resistance which should result from the configuration of the resistor track  88  as originally printed. If, however, the play spot has been removed or lifted, the measured resistance will be substantially different than the predetermined electrical signature of the track  88 .  
     [0198] The T-square circuit  200  can determine the authenticity and integrity of the ticket  50  as a whole, of the individual play spot areas  72 A-H, and of the bar code  80 . If no resistance can be measured for any of the resistor tracks  82 - 96 , it can be assumed that either the ticket  50  is a counterfeit or that all of the play spot areas  72 A-H have been rubbed off thereby rendering the ticket  50  void. Moreover, because the T-square circuit  200  provides a different individual circuit for each of the resistor tracks  82 - 96 , the T-square circuit  200  can individually test the integrity of the individual play spot areas  72 A-H.  
     [0199] For example, a particular probability game may require revealing three matching game indicia to win. In addition, the game rules may require that no more than three play spot areas be rubbed off to reveal the underlying indicia. Consider the hypothetical situation in which an individual presents the ticket  50  to a lottery agent for redemption because the individual has ostensibly rubbed off only three play spot areas and the indicia in the three play spot areas match. By pure visual inspection, the ticket  50  might appear to be a valid and winning ticket. However, when the ticket  50  is inserted into the ticket slot  182  of the electronic verification machine  108  to measure the resistance of the play spot areas  72 A-H, the electronic verification machine  108  would determine that not only the measured resistances of the three rubbed-off play spot areas differ from the predetermined resistances for these play spot areas, but also that the measured resistance of other “non-rubbed-off” play spot areas differ from the predetermined resistances for these areas. This situation could arise, for example, when the individual removes the overprint areas  68  of these additional play spot areas to reveal the hidden indicia  74  and then attempts to replace the overprint areas  68  so that these play spot areas appear to not have been played. Thus, although visually the ticket  50  appears to be a valid winning ticket, the measure of the resistances  82 - 96  would indicate that more than three play spot areas have been removed and that therefore the ticket  50  is void. In addition, if the measured resistance of the bar code resistor track  107  is substantially different from the predetermined electrical signature for the bar code  80 . it can be assumed that the bar code  80  has been tampered with as well.  
     [0200] 2. The Binary Coupled Circuit.  
     [0201] An alternative embodiment of a ticket  250  having a partial printed circuit  252 , termed a binary coupled circuit, is shown in FIG. 21. The partial circuit  252  is analogous to the seventh layer  164  printed on the ticket  50 . As with ticket  50 , the partial circuit  252  is ultimately printed on a ticket substrate  254  preferably using a conductive ink of the type described in Table 2. Although not shown, it is to be understood that additional layers such as a lower conductive layer analogous to the first layer  146  of ticket  50 , a blocking layer and a primer layer analogous to the second layer  156  and third layer  158  of the ticket  50 , play indicia analogous to the play indicia  74  of ticket  50 , a seal coat and release coats analogous to the fourth layer  160  and the fifth and sixth layers  162  of the ticket  50  are also printed on the ticket  250  between the substrate  254  and the partial circuit  252  in a manner similar to that used for ticket  50 .  
     [0202] The ticket  250  includes a display portion  256  and a playing field portion  258 . The display portion  256  is ultimately covered by a coating (not shown) suitable for receiving customized graphics (not shown) and information (not shown) related to the rules for playing the ticket  250 . The playing field portion includes two columns of four, separately removable play spot areas  260 - 274 . Within the playing field portion  258 , the partial circuit includes several conductive areas  276 - 292  and eight resistor tracks  294 - 308 . Each of the play spot areas  260 - 274  is positioned between two conductive areas, for example, play spot area  260  is positioned between conductive areas  276  and  278  and play spot area  262  is positioned between conductive areas  278  and  280 . Each of the resistor tracks  294 - 308  is also positioned between and electrically connected to two of the conductive areas  276 - 292 . For example, resistor track  294 , associated with play spot area  260 , is positioned between and connected to conductive areas  276  and  278 . Underlying each of the play spot areas  260 - 274  is a conductive line (not shown). Each conductive line is connected to the two conductive areas associated with its respective play spot area and resistor track. For example, the conductive line underlying play spot area  260  is connected to conductive areas  276  and  278 .  
     [0203] The three additional conductive areas  310 - 314  are printed in the display portion  256  of the ticket  250 . The first conductive area  310  is connected to the first column of four play spots  269 - 266  via a conductive track  316  connected to the conductive area  284 . The second conductive area  312  is connected to the second column of four play spots  268 - 274  via a second conductive track  318  connected to the conductive area  292 . All eight play spot areas  260 - 274  are connected to the third conductive area  314  via a third conductive track  320  connected to the conductive area  276 . The conductive areas  310 - 314  serve as capacitor plates when the ticket  250  is coupled to an electronic verification machine.  
     [0204] Each column of four play spot areas  260 - 266  and  268 - 274  forms one complete circuit when the ticket  250  is coupled to the electronic verification machine  108 . The excitation signal from the electronic verification machine  108  is routed through each group of four play spot areas  260 - 266  via the common conductive area  314  in the display portion  256  of the ticket  250 . Each group of four play spot areas  260 - 266  and  268 - 274  provides its own detection signal. The detection signal for the play spot areas  260 - 266  is coupled to the electronic verification machine  108  via the conductive track  316  and the conductive area  310 . The detection signal for play spot areas  268 - 274  is coupled to the electronic verification machine  108  via the conductive track  318  and the conductive area  312 .  
     [0205] Within a group of four play spot areas, for example play spot areas  260 - 266 , the magnitude of the detection signal varies with the integrity of each of the play spot areas  260 - 266 . If the play spot areas  260 - 266  are intact, the excitation signal is substantially unaltered and is routed through the conductive lines underlying each of the play spot areas  260 - 266 . However, if a play spot area has been rubbed off or lifted to reveal the underlying play indicia, the signal is routed through the resistor track associated with that play spot area. For example, if play spot area  260  is intact, the signal proceeds through the underlying conductive bar to the conductive area  278 . However, if the play spot area  260  has been at least partially removed to reveal the underlying play indicia, the circuit through the conductive line is broken thus routing the signal through the associated resistor track  294  thus changing the characteristics of the detection signal.  
     [0206] In the preferred embodiment of this ticket  250 , each of the resistor tracks associated with a group of four play spot areas, such as the resistor tracks  294 - 300  associated with play spot areas  260 - 266  has a unique predetermined resistance that is related, in a binomial progression, to the other resistor tracks in the column. For example, resistor track  294  can have a predetermined electrical signature equal to a resistance of 100 KΩ, resistor track  296  can have a predetermined electrical signature equal to a resistance of 200 KΩ, resistor track  298  can have a predetermined electrical signature equal to a resistance of 400 KΩ, and resistor track  300  can have a predetermined electrical signature equal to a resistance of 800 KΩ. The resistor tracks, such as resistor tracks  294 - 300 , are printed in parallel to the conductive lines underlying the play spot areas, such as play spot areas  260 - 266 . As explained below, the binomial relationship of the printed resistances for each resistor track within a group of four resistors tracks permits determination of the integrity of each play spot even though only one detection signal is produced for all four resistor tracks.  
     [0207]FIG. 22 is a partial schematic circuit diagram  324  illustrating the coupling of one column of four resistor tracks  260 - 266  to the excitation and detection circuitry of the electronic verification machine  108 . The parts of the circuit which are contributed by the ticket  250  include the four resistor tracks  294 - 300 , the conductive areas  276 - 284 , the conductive lines  316  and  320 , and the conductive areas  314  and  310 . In addition, the ticket partial circuit includes four conductive lines  326 - 332  which underlie the play spot areas  260 - 266 . The play spot areas  260 - 266  do not actually form a part of the circuit but are included in FIG. 22 for ease of understanding.  
     [0208] The remainder of the excitation and detection circuit is provided by the electronic verification machine  108 , including a pair of capacitor plates  334  and  336 . The capacitor plates  334  and  336  can consist of, for example, copper plates positioned within the electronic verification machine  108  to mirror the configuration of the conductive areas, such as conductive areas  310  and  314 , on the ticket  250 . When the ticket  250  is coupled to the electronic verification machine, the excitation and detection circuit is completed by the capacitive coupling of the capacitor plates  334  and  336  in the electronic verification machine with the conductive areas  314  and  318  printed on the ticket  250 . The excitation signal is applied to the ticket  250  via one of the capacitors formed by one of the capacitor plates, for example the capacitor  334 , with the conductive area  314  printed on the ticket  250 . The detection signal is routed to the rest of the excitation and detection circuit via the capacitor formed by the other capacitor plate in the electronic verification machine, for example plate  338 , with the conductive area  310  printed on the ticket  250 .  
     [0209] When the play spots  260 - 266  have not been removed or tampered with, as illustrated in FIG. 22, the excitation signal flows through the each of the four conductive lines  326 - 332 . However, removing or partially removing one of the play spots  260 - 266  effectively breaks the circuit through the associated conductive line rerouting the signal through the associated resistor track. For example, if play spot  260  is removed, the signal pathway would go through resistor track  294 . Because each resistor track  294 - 300  has its own unique resistance, each resistor track  294 - 300  produces its own unique detection signal thereby permitting the electronic verification machine  108  to identify which, if any of the play spot areas  260 - 266  have been lifted or removed. Moreover, since the resistance values of the resistor tracks  294 - 300  are related to each other as a binomial progression, the electronic verification machine  108  can also identify which of the play spots  260 - 266  have been removed when two or more of the play spots  260 - 266  have been removed. For example, if both play spots  260  and  262  are removed the combination of resistor tracks  294  and  296  adds 300 KΩ to the excitation and detection circuit. However, if play spots  260  and  264  are removed, the combination of resistor tracks  294  and  298  adds 500 kΩ to the excitation and detection circuit. Thus, because the resistor tracks  294 - 300  have resistance values that are related as a binomial progression, each possible combination of resistor tracks  294 - 300  results in a unique total resistance which can be used to identify the play spots  260 - 266  that have been removed. Table 3 lists all the possible combinations of resistor tracks  294 - 300  and the resulting resistance values for the previously identified resistance values for the resistor tracks  294 - 300 .  
               TABLE 3                          Resistor Combinations                             Resistors In The Circuit   Effective Resistance                                         R1   100           R2   200           R3   400           R4   800           R1 + R2   300           R1 + R3   500           R2 + R3   600           R1 + R2 + R3   700           R1 + R4   900           R2 + R4   1000           R1 + R2 + R4   1100           R3 + R4   1200           R1 + R3 + R4   1300           R2 + R3 + R4   1400           R1 + R2 + R3 + R4   1500                      
 
     [0210] Additional resistance values and combinations of resistance values are possible. For example, the resistance values in Table 3 could be increased or decreased by an order of magnitude. The principle of this circuit design is that the individual resistance of each resistor track within a group of resistor tracks, such as resistor tracks  294 - 300 , should be algorithmically related to the resistances of the other resistor tracks within the group so that every combination of resistor tracks provides a unique total resistance. Preferably, the individual resistances should vary as a binomial progression.  
     [0211] 3. The Infinite Resistance Circuit.  
     [0212]FIGS. 23, 24,  25  and  26  illustrate another partial printed circuit which can be used to validate and determine the authenticity and integrity of a document which in this example is a lottery ticket  340 . As shown in FIG. 23, the lottery ticket includes play indicia  342  which are printed over the ticket substrate  344 . Additional information, such as the name of the lottery game  346  and rules  348  for playing the ticket are also printed on the ticket substrate  344 . FIG. 24 is a plan drawing of the scratch-off coating  350  which is printed over and conceals the play indicia  342 . The scratch-off coating  350  is a removable layer of a material such as latex which can be relatively easily removed to reveal the play indicia  342 . A single block of scratch-off coating  350  is used to cover all of the play indicia  342 . A release coat (not shown) coincident with the scratch-off coating  350  is also printed on the ticket  340  between the play indicia  342  and the scratch-off coating  350 . FIG. 25 is a plan drawing of the partial printed circuit which is used to determine the integrity and authenticity of the ticket  340 . The circuit consists of a single conductive area indicated at  352 A and  352 B which overlies the scratch-off coating  350 . The two portions  352 A,  352 B of the conductive area extend beyond the edges of the scratch-off coating  350 . FIG. 26 is a plan drawing of the ticket  340  in its final printed state which includes overprint areas  354  that conceal the scratch-off coating  350  and the conductive area  352 , as well as overprint areas  356  that define the individual play spot areas.  
     [0213] When the ticket  340  is coupled to the electronic verification machine  108  the portions  352 A and  352 B serve as capacitor plates to couple the partial circuit printed on the ticket  340  with the excitation and detection circuitry in the electronic verification machine  108 . The portion of the conductive track  352 A-B which immediately overlies the scratch-off coating  350  but does not extend beyond the scratch-off coating  350  serves as a resistor track when the ticket  340  is coupled to an electronic verification machine  108 . If the ticket is in its original integral state, the portion of the conductive area  352 A-B immediately overlying the scratch-off layer  350  is electrically connected to the portions  352 A and  352 B which serve as capacitor plates. However, if an individual has attempted to surreptitiously inspect the play indicia  342  by, for example, lifting and then replacing the scratch-off layer  350 , the electrical connection between the middle portion of the conductive layer and the end portion  352 A and  352 B would be broken resulting in an open circuit.  
     [0214] 4. The Increased Resistance Circuit.  
     [0215]FIG. 27 illustrates an alternative embodiment of a scratch-off layer  358  for the ticket  340 . Unlike the previously described scratch-off layer  350 , the scratch-off layer  358  consists of discreet, individual areas which overlie each play indicia  342  (not shown). A release coat (not shown) underlies each of the discreet portions of the scratch-off coating  358 . The partial printed circuit which overlies the scratch off layer  358  consists of a single conductive area indicated at  360 A and  360 B which overlies all of the scratch off layer  358 . Two portions  360 A,  360 B of the conductive area  360  extend beyond the area of the ticket  340  containing the scratch-off coating  358 . The final printed format of the ticket  240  is shown in FIG. 26 and includes overprint areas  354  that conceal the scratch-off coating  358  and the conductive area  360 A-B, as well as overprint areas  356  that define the individual play spot areas.  
     [0216] When the ticket  340  is coupled to an electronic verification machine  108 , the portions  360 A and  360 B of the conductive area  360  which extend beyond area of the ticket  340  containing the scratch-off layer  358  serve as capacitor plates to couple the partial circuit printed on the ticket  340  with the excitation and detection circuitry in the electronic verification machine  108 . The portion of the conductive area  360 A-B which immediately overlies the scratch-off coating  358  but does not extend beyond the scratch-off coating  358  serves as a resistor track when the ticket  340  is coupled to the electronic verification machine  108 . If all of the play spots are intact, the electrical signature of the ticket  340  will be equal to the printed resistance associated with the portion of the conductive track  360  which overlies all of the play indicia  342 . However, if an individual has attempted to surreptitiously inspect the play indicia  342  by, for example, lifting and then replacing one portion of the scratch-off layer  358 , the small portion of the conductive area  360 A-B immediately overlying the removed area of the scratch-off layer  258 , will be electrically disconnected from the remainder of the conductive area  360 A-B, leading to an increase in the resistance associated with the conductive area  360 A-B.  
     [0217] 5. The Waffle Circuit.  
     [0218]FIG. 29 is a plan drawing of another partial circuit  364  which can be printed on a lottery ticket to determine the authenticity and integrity of the play spot areas. The partial circuit, termed a waffle circuit, includes two conductive bars  366  and  368  which are electrically connected to a conductive area  370  overlying the play indicia (not shown). Removable scratch-off areas  372  overlie the portions of the conductive area  370  which immediately overlie the individual play indicia. A seal coat and release coats analogous to the forth layer  160  and the fifth and sixth layers  162  of the ticket  50  in FIG. 11 are printed in an appropriate configuration between the play indicia and the conductive area  370 . Thus, removal of any of the scratch-off areas  372  also removes a portion of the conductive area  370 . When the ticket which includes the partial circuit  364  is coupled to the electronic verification machine  108 , each of the play spot areas defined by the scratch-off areas  372  serves as a capacitor plate. In addition, the conductive bars  366  and  368  also serve as capacitor plates to couple the partial circuit  364  to the excitation and detection circuitry of the electronic verification machine  108 . The excitation and detection circuitry of the electronic verification machine  108  in turn includes an array of capacitive couplers which are positioned to mirror the configuration of the conductive bars  366  and  368  and the scratch-off areas  372 . Thus, in contrast to the previously described partial circuits in FIGS. 20, 21, and  23 - 28 , the electrical signature of the play spot areas associated with the partial circuit  364  is a conductive track, rather than a resistive track.  
     [0219] The electronic verification machine  108  can check the authenticity and integrity of the play spot areas defined by the scratch-off areas  372  by applying an AC excitation signal to one of the conductive bars  366  or  368 . If the individual play spot area being tested is intact, the excitation signal will be routed through the portion of the conductive area  370  underlying the scratch-off area  372  associated with the tested play spot area. Consequently, an AC detection signal will be routed to the capacitor plate in the electronic verification machine  108  which mirrors the particular play spot area  372 . However, if the scratch-off area  372  being tested has been at least partially removed, the associated removal of a portion of the conductive area  370  creates an open circuit under that particular scratch-off area  372 . Hence, no AC detection signal is routed to the associated capacitor plate in the electronic verification machine  108 , indicating that the integrity of the play spot area  372  has been changed.  
     [0220] 6. The Recursive Circuit.  
     [0221]FIG. 30 is another plan drawing of a partial printed circuit  376  which can be used to determine the authenticity and integrity of the play spot areas of a lottery ticket. The partial circuit  376  includes resistor tracks (not shown) which underlie each of the removable scratch-off areas  378 . Each resistor track is electrically connected to a pair of conductive bars  380 A and  380 B. In the partial circuit shown in FIG. 30, there are a total of twenty-four conductive bars  380 A,  380 B, two for every resistor track associated with one of the scratch-off areas  378 . When the ticket which includes the partial circuit  376  is coupled to an electronic verification machine  108 , each resistor track associated with each scratch-off area  378  is capacitively coupled to the excitation and detection circuity of the electronic verification machine  108  by its associated conductive bars  380 A and  380 B. One conductive bar, for example, bar  380 A, is used to apply the excitation signal to the resistor track. The second conductive bar, for example bar  380 B, routes the detection signal to the rest of the excitation and detection circuitry in the electronic verification machine  108 . If the scratch-off area  372  being tested is intact, the electrical signature of the associated resistor track will be substantially equal to the printed resistance of the resistor track underlying the scratch-off area  372 . If, however, the scratch-off area  372  being tested has been at least partially removed or lifted, the measured resistance of the resistor track and hence the resonant frequency of the completed circuit associated with the scratch-off area  372  will be substantially different than the printed resistance of the resistor track.  
     [0222] C. Variation In Printed Resistances  
     [0223] 1. Variations In The Printed Resistances.  
     [0224] A number of the foregoing circuits, such as the T-square circuit shown in FIG. 20., and the binary-weighted circuit shown in FIG. 21, use the resistance of a printed resistor track to impart an electrical signature to a document. As noted earlier, the resistance of such printed resistor tracks can be defined as follows:  
       R=ρ ( L/A )  
     [0225] where R=resistance;  
     [0226] ρ=bulk resistivity (resistance per unit volume);  
     [0227] L=length of resistor; and  
     [0228] A=cross sectional area of the resistor.  
     [0229] The cross-sectional area of the resistor in turn equals the product of the print thickness (t) and the width (W) of the resistor. Substituting these parameters yields the following formula for the resistance of a printed resistor track:  
       R=ρ ( L/tW )  
     [0230] Thus the resistance of a printed resistor track such as those used in the previously described circuits is a function of the bulk resistivity of the ink used to print the resistor, the length of the resistor track, the thickness of the printed track and the width of the printed track. Resistor tracks having different resistances can thus be formulated by varying any of these parameters. In practice, changing the resistivity of the inks used in order to create different resistor tracks having different resistances may be impractical because, at least in a gravure printing process, changing inks requires using a different printing station. The other parameters, however, can be easily and effectively varied to provide different resistor tracks within one circuit which have different resistances. FIG. 31 is a plan drawing of four different resistor tracks  384 - 390 . Because the length and widths of the resistor tracks  384 - 390  differ, the resistances of the resistor tracks  384 - 390  will be different even if the resistor tracks  384 - 390  are printed with exactly the same conductive ink. Thus, for example, the resistor tracks  386  and  388  would have different resistances even though the lengths of the resistor tracks  386  and  388  are approximately equal because the widths of the resistor tracks  386  and  388  are not the same. Thus, the resistance of the resistor tracks printed on a document, such as the ticket  50 , can be varied by varying the dimensions of the printed resistor tracks.  
     [0231] 2. Variations In The Measured Resistances.  
     [0232] Variations in ink resistivity can also occur over the course of a large print run. These variations in resistivity are due to a number of factors including printing process temperature and viscosity variations. Consequently, these variations are only detectable over a large number of tickets that were printed over a long period of time. The resistivity of the ink on a single ticket does not fluctuate in this manner. However, the resistance of a resistor track printed at the beginning of a print run can be measurably different than the resistance of an identical resistor track printed with the same conductive ink at the end of a print run due to these time-dependent variations in the resistivity of the conductive ink. Consequently, it is desirable that these time dependent variations in the electrical signature be compensated for when the electronic verification machine  108  tests the authenticity and integrity of the document.  
     [0233] The electronic verification machine, such as electronic verification machine  108 , compensates for such time-dependent variations in the measured electrical signature in one or both of two ways: (1) by establishing that the measured values are accurate within a specified range of an expected value; or (2) by using a separate circuit element to establish the precision of the measured electrical signature.  
     [0234] In the preferred embodiment, the electronic verification machine compensates for time dependent variations in the electrical signature by determining that the measured values are accurate within a range of, for example, 10 percent, of the expected electrical signature. Thus, for example, a measured resistance that is expected to be 500Ω would be acceptable as long as the resistance was in the range between 450Ω and 550Ω. In other words, if the measured resistance was within this range, the corresponding play spot is treated by the electronic verification machine  108  as not having been rubbed off and therefore as being in its original integral state as well as presumably authentic.  
     [0235] If the time dependent variations in the electrical signature are corrected by using a precision system, the partial circuit printed on the ticket must contain an additional element, a calibration line, which is used to determine if a measured resistance is precise. FIG. 32 is a plan drawing of an alternative embodiment of a T-square circuit  392  which includes a calibration line shown generally at  394 . The calibration line  394 , termed a John Galt line, includes a resistor track  396  connected to a conductive area  398 . The remaining elements of the partial printed circuit  392  are analogous to and function in the same manner as the T-square circuit shown in FIG. 20. Hence, the remaining elements of the circuit  392  in FIG. 32 correspond to the circuit elements shown in FIG. 20. The calibration line  394  is connected to the rest of the circuit  392  via the central conductive area  100 . The resistor track  396  is printed on a portion of the ticket which does not include play spot areas. Consequently, the resistor track  396  should remain in its original integral state after the ticket has been played. When a ticket containing the calibration line  394  is coupled to the electronic verification machine  108  the resistor track  396  is coupled to the excitation and detection circuitry of the electronic verification machine  108  by the capacitors formed by coupling the conductive areas  100  and  398  to capacitor plates in the electronic verification machine  108 .  
     [0236] In the partial circuit  392  shown in FIG. 32, the calibration line  394  is used to determine how far the measured resistances of a particular ticket should deviate from the expected value for these resistances. For example, if the calibration line  394  is printed with an expected resistance of 500Ω, but measured resistance of the calibration line  394  on a particular ticket actually has a calibration value resistance of 525Ω, the five percent increase over the expected value should be seen in other resistances on the card as well. Therefore, even if a measured resistance of a play spot area is within the acceptable value of 10 percent above or below the expected value, it should be approximately five percent higher than the expected value in order to be precise for this ticket. Thus, if a given resistance corresponding to one of the play spots is eight percent below the expected value and therefore within plus or minus ten percent of the expected resistance, the spot would be deemed to have been played because the resistance, although accurate, is not within the calibrated precision for this ticket.  
     [0237] D. Protection Of The Bar Code  
     [0238] A circuit printed on a lottery ticket, such as the circuit  81  printed on the ticket  50  shown in FIG. 2, can include a partial printed circuit which provides an electrical signature to protect the bar code  80 . As noted with reference to FIG. 19, the bar code partial circuit includes a resistor track  107  connected to two conductive areas  150  and  104 . In addition, the conductive area  150  immediately underlies the conductive area  106  of the partial printed circuit  164  used to determine the authenticity and integrity of the play spot areas, as shown in FIGS.  2  and G. Hence the partial printed circuit for the bar code  80  and the partial printed circuit  164  for the play spot areas are electrically connected via the overlying relationship of the conductive areas  106  and  150 . Consequently, when the electronic verification machine  108  transmits the excitation signal to the ticket  50  via the central conductive track  100 , the excitation signal can be routed to the bar code partial circuit via the conductive areas  106  and  150 . The detection signal from the bar code  80  is routed to the remaining excitation and detection circuitry via the capacitor formed by the conductive area  104  and a capacitor plate in the electronic verification machine  108 .  
     [0239] The bar code  80  is in turn printed on the ticket  50  to at least partially overlie the bar code partial circuit. In the preferred embodiment shown in FIGS. 1 and 2, the bar code  80  is printed on the ticket  50  so that it overlies the conductive area  104 . Alternatively, the bar code  80  could be printed to overlie the resistor track  107 . In either embodiment, attempts to alter the bar code  80 , for example by substituting the bar code  80  of the ticket with the bar code of a different ticket, would result in changes in the measured electrical signature of the bar code  80  by changing either the resistance or the capacitance of the bar code partial circuit.  
     [0240] E. Alternative Circuit Designs  
     [0241] In addition to resistors, other types of electrical circuit elements can be used in a printed circuit to produce electrical circuits. For example, the elements used to couple a document, such as the ticket  50 , to an electronic verification machine  108  are not limited to capacitor plates or areas but can also include inductive, radio frequency, and optical frequency circuit elements. In addition, the form of the electrical signature can be varied so that a properties other than resistance can be used to validate or determine the authenticity and integrity of a document. Examples of alternative electrical signatures include gain, amplitude, frequency, oscillation, and thermal effects.  
     [0242] 1. Coupling  
     [0243] There are a number of methods by which a circuit printed on a document, such as the circuit  81  on the ticket  50 , can be coupled to the electronic verification machine  108  including direct, capacitive, inductive, radio frequency and optical coupling methods. In direct coupling, the ticket is coupled to the electronic verification machine via direct physical contact of one or more conductive areas on the ticket with an electrical element, such as a contact plate, within the electronic verification machine  108 . Although it is relatively straightforward to implement, direct coupling has the potential disadvantage of signal distortions which can arise from surface imperfections or impurities on the conductive areas of the ticket.  
     [0244] In capacitive coupling one or more conductive areas such as the areas  98 A-H of the ticket  50  shown in FIG. 2 form one plate of a capacitor. The other plate of the capacitor is provided by a metal plate connected to the circuitry of the electronic verification machine  108 . As described previously, the resulting capacitor can be used to form part of a verification circuit  225  as shown in the block diagram of FIG. 18. Here the conductive areas  98 A-C of the ticket  50  form capacitors with the plates  200 - 204  of the electronic verification machine  108 .  
     [0245] Inductive coupling is similar in that a ticket  400  is printed with a circular conductive area  402  as illustrated in the example of FIG. 33. The electronic verification machine  108  would then include a coil  404  that is inductively coupled with the circular conductive area  402  when the ticket  400  is inserted in the electronic verification machine  108 . There are a variety of configurations that can be used including a number of inductors printed on the ticket  400  that would be inductively coupled with a corresponding number of coils in the electronic verification machine  108 .  
     [0246] Radio frequency can also be used for verification as shown in FIG. 34. In this case a planar transmission line  406  is printed on a ticket  408  which is separated by the ticket substrate  410  from a ground plane  412  printed on the other side of the substrate  410 . With this structure radio frequency energy is transmitted and received in a transverse electromagnetic mode. Using this approach verification signals can be transmitted to the circuits printed on the ticket  408  from suitable antennas located in the electronic verification machine  108 .  
     [0247] In addition, optical frequency can be used for verification where for example a photo emitter conductor or semiconductor is printed on the ticket  50  and is electrically stimulated to emit light at an infrared frequency. Photo-detectors on the electronic verification machine  108  can be used to detect and classify the frequency of the light emitted by the ticket  50  in contrast to the nominal reflective background of the ticket  50 .  
     [0248] 2. Signature Verification  
     [0249] There are a number of methods for verifying the authenticity or integrity as well as to determine the redemption value of a lottery ticket, such as the ticket  50 , using the electronic verification machine  108 . One method is to merely check for an open circuit in the circuit printed on the ticket  50 . Here a signal is applied to the ticket circuit by one of the techniques described above and if no current flow is detected then it can be assumed that a play spot  72 A-H has been removed or that the ticket has been tampered with.  
     [0250] Gain can also be used where the electronic verification machine  108  includes an operational amplifier and the circuit element printed on the ticket  50  serves in its feedback loop. The gain of the operational amplifier will reflect any changes in the ticket circuit and thus can be used to detect tampering or to determine which play spots  72 A-H have been scratched off by the player.  
     [0251] The amplitude of the voltage, current or power of the AC signal flowing through circuit printed on the ticket  50  can additionally be measured by the electronic verification machine  108  to indicated changes in the circuit that would reflect alterations in the ticket  50 .  
     [0252] The phase of a signal flowing thought the circuit printed on the ticket  50  can also be checked by the electronic verification machine  108  against an expected or predetermined value to determine changes in the circuit.  
     [0253] Frequency of the electrical signal induced in the circuit printed on the ticket can be measured by the electronic verification machine to detect changes in the ticket. This is an especially useful approach where the circuit on the ticket  50  includes elements such as capacitors or inductors which can affect frequency.  
     [0254] A measure of oscillation frequency can also be used where the circuit printed on the ticket combined with the circuit in the electronic verification machine forms  108  an oscillator or where a complete oscillator circuit is printed on the ticket  50 . Here an expected oscillation frequency can be used to detect changes in the ticket  50 .  
     [0255] It should be noted that other methods can be used to determine which of the play spots  72 A-H of the probability ticket  50  have been scratched off. For example, an optical card reader system of the type described in U.S. Pat. Nos. 4,736,109 and 4,760,247 or a laser system of U.S. Pat. No. 5,903,340 can be used to read a security code imprinted on the overprint areas  66  of ticket  50  to determine which of the play spots have been rubbed off in the manner generally described in U.S. Pat. No. 5,887,906. These systems can then perform the function of the sensor arrays  502  and  1036  and the related circuits of FIGS. 38 and 99 respectively, as described in connection with those figures below, to determine if the play spots  72  A-H have been rubbed off.  
     [0256] Thermal effects are another phenomena that can be used by the system described above to detect tampering or determine which play spots have been removed from a ticket  414  of the type shown in FIG. 35. In this case heat generated by current flowing though a set of resistors  416 A-D is detected by a group of infrared photodetectors  418 A-D located in the electronic verification machine  108 . When one or more of a set of play spots  420 A-D is removed current will no longer flow though its associated resistor and the resulting lack of infrared radiation would indicate that the spot(s) had been removed.  
     [0257] Capacitance and inductance changes in the circuits printed on the ticket  50  can likewise be detected by the electronic verification machine  108  indirectly from the frequency characteristics of the circuits in order to determine whether changes have occurred on the ticket  50 .  
     [0258] V. Validation of Lottery Tickets  
     [0259] Validation of the lottery ticket  50  as well as the determination the authenticity and integrity of a document, such as ticket  50 , can involve the interaction of several steps. As an example, a description of a preferred method for validating the lottery ticket  50  of FIG. 1 using the electronic verification machine  108  of FIG. 14 is provided below. When an individual presents the ticket  50  to a lottery agent for redemption, the lottery agent insert the ticket  50  into the electronic verification machine  108 . The electronic verification machine will read the bar code  80 , which contains the inventory control number and encrypted validation number data, and it will sense which of the play spots  72 A-G have been removed. The lottery agent then enters the validation number  78  of the ticket  50  into the electronic verification machine  108  via the user interface  178 . As noted earlier, the validation number  78  contains information related to the identity of a specific ticket, such as the pack and ticket number. In addition, in the preferred embodiment the validation number  78  also contains information related to the electrical signatures of the circuit elements printed on the ticket  50 . For example, the ticket  50  has two electrical signatures. One signature is the expected resistance of the bar code resistor track  107 . The second is the expected resistance of the play spot resistor tracks  82 - 96  which all have the same value. If the play spot resistor tracks had different expected values, such as the resistor tracks  294 - 308  in the partial circuit  292  shown in FIG. 21, information related to each electrical signature could be stored in the validation number  78  of the ticket  50 . Alternatively, the information related to the electrical signature(s) of the circuit elements printed on the ticket  50  could be stored in a look-up table in the microprocessor on the processor board  220  in the electronic verification machine  108  or the central computer  223 . In this case, the validation number  78  or the encrypted validation number printed in the bar code  80  is used primarily to correlate the particular ticket being tested with the electrical signature information stored in the computer. Alternatively, data related to the expected signal can be contained in the validation number  78 . In either case, the validation number provides the primary method for accessing the information related to the expected electrical signature(s) of the ticket.  
     [0260] After the ticket  50  is coupled to the electronic verification machine  108  via the ticket interface  176 , the electronic verification machine  108  completes the discreet verification process for each of the play spot resistor tracks  82 - 96 , as explained above in Section IV.A. The electronic verification machine determines the measured electrical signature for each of the play spot resistor tracks  82 - 96  and compares these values to the value or values stored either in the validation number  78  of the ticket  50  or in a look-up table in the central computer  223  or the processor board  220 . If the measured resistance of a specific play spot resistor track  82 - 96  is substantially the same as the stored value of the resistance, the associated play spot area  72 A-G is in its original integral state and has not been at least partially removed. If, on the other hand, the measured resistance is substantially different than the stored value for the resistance, the associated play spot area  72 A-G is treated by the electronic verification machine  108  as having been removed. This occurs, for example, when the associated play spot area has been at least partially removed by a player playing the ticket or when the ticket has been tamped with.  
     [0261] In this particular example, the ticket  50  is considered valid only if the number of play spot areas  72 A-G specified in the rules  58  have been removed to reveal the underlying play indicia  74 . For example, the rules  58  for a particular game may require rubbing off only three play spot areas  72 A-G. If an individual rubs off more than three play spot areas  72 A-G, the ticket  50  is void even if three of the revealed play indicia  74  match. If the electronic verification machine  108  determines that the ticket  50  is valid, that is the ticket  50  has been played according to the rules  58 , the electronic verification machine  108  then proceeds to determine the redemption value of the ticket  50 .  
     [0262] The electronic verification machine  108  can validate or determine the redemption value of the ticket, such as ticket  50 , in either of two ways: (1) by accessing the play indicia value data stored in the bar code  80  on the ticket  50 ; or (2) by accessing a ticket redemption file contained in the central computer  223  or the processor  220 . Storing the play indicia value data in the bar code  80  has the advantage of permitting local determination of the redemption value of the ticket  50 . Consequently, any lottery terminal can determine the redemption value of a ticket without contacting a central lottery or host computer thus reducing the cost and time required in the redemption process. On the other hand, it is not inconceivable that the play spot value code in the bar code  80  could be broken even though there are a very large number of potential play spot value combinations that can be printed on the ticket  50 . As a result there is some possibility that an individual could predict the winning combinations present on ticket  50  based upon the bar code  80 . Maintaining a separate ticket redemption value file in the central computer  223  or the processor  220  will normally result in increased ticket security because the play indicia value data are not stored in a bar code  80  on the ticket  50 . Such a system, however, requires communication with the central computer  223  or the processor  220  in the electronic verification machine  108  before the ticket  50  can be redeemed. As a result, this type of redemption process, especially where a remote central computer  223  is used, can be slower and more costly than storing the play indicia value data in the bar code.  
     [0263] In the preferred embodiment of the invention, therefore, the method of storing play indicia or redemption value data in the bar code  80  typically would be used only for low level prizes. The larger cash prizes would be computed by the lottery central computer  223  in order to increase the security of the system with respect to high tier prizes or redemption values. In this embodiment, the bar code  80  would store information concerning all the play indicia  74  on the ticket  50 . The bar code  80  can consist of, for example, 22 digits which represent a game number (2 digits), a pack number (6 digits), a check digit (1 digit), a ticket number (3 digits) and a play spot code (10 digits). The game number is unique to each particular lottery game. The pack number identifies the pack from which a particular ticket originates. The check digit is used to help ensure that a proper bar code read has been made. The ticket number relates the relative position of a specific ticket within a pack. In this example, the game number, the pack number and the ticket number represent ticket identification or accounting data and normally in themselves do not contain redemption value information.  
     [0264] The 10-digit play spot code includes a value portion containing information about the value of each of the play indicia of each of the play spots areas. An illustration of how such a 10-digit play spot code can be used in a probability lottery ticket  422  is provided in FIGS. 36 and 37. Referring to FIG. 36, the ticket  422  has sixteen play spots areas  424 A-P each of which covers a play indicia  426 A-P which are shown in FIG. 37. The ticket  422  also includes a bar code  428  and a void-if-removed area  430  which conceals a validation number (not shown) as well as a set of printed information  432  concerning the rules for playing the ticket  432 . In the example illustrated in FIGS. 36 and 37, the rules  432  state that only six play spot areas  424 A-P may be removed. The ticket  422  can be redeemed for a prize if any two of the revealed play indicia  426 A-P match. FIG. 37 illustrates the ticket  422  after all of the play spot areas  424 A-P have been removed to reveal the underlying play indicia  426 A-P.  
     [0265] For a ticket with 16 play spots areas, such as the ticket  422 , two bits of the value portion in the play spot code are used to store information concerning the value of the play indicia  426 A-P for each play spot area  424 A-P. In this example, the values of these bit pairs are as follows: “00” signifies that the value of the play spot area cannot be checked locally by the electronic verification machine  108 ; “01” signifies that the value of the play indicia equals $1.00; “10” indicates that the value of the play indicia equals $2.00; and “11” indicates that the value of the play indicia equals $5.00. In other words, all play indicia that contain the $1 symbol are represented by the bit pattern “01”, play indicia that contain a $2 symbol are represented by the bit pattern “10 ”, and play indicia that contain the $5 symbol are represented by the “11” bit pattern. Any play indicia having a value other than $1, $2 or $5 has a corresponding bit pattern of “00”. Thus, for example, all play spots having $10, $20, $50 or $100 symbols would have corresponding bit patterns of “00”. The bit pattern “00” indicates that the play indicia value for the corresponding play spot area  424 A-P cannot be determined locally and must be determined by accessing the redemption file in the central computer  223 . The bit patterns for all of the play indicia  426 A-P are strung together to form a 32-bit binary number. For example, the 32-bit binary number corresponding to the play indicia  426 A-P would be as follows:  
     [0266] 11 00 00 00 00 11 00 00 00 00 11 00 00 00 00 01  
     [0267] This binary number then is converted to base 10 in which the 32-bit number is represented by 10 digits, in this case 3,224,374,273. These 10 digits are encrypted to form the play spot code which forms a part of the bar code  428 . It should be noted that the 32-bit binary number can also be converted to numbers having other bases such as hexadecimal. For example, the hexadecimal value of the above 32-bit binary number would be C0300C01.  
     [0268] The bar code reader  210  in the electronic verification machine  108  reads the bar code  428  including the play spot code. The computer on the processor board  220  in the electronic verification machine  108  decrypts the 10 digit, base 10 play spot code and then converts it to a binary number thereby creating a 32-bit number with a 2-bit code corresponding to each of the 16 play indicia  426 A-P. The computer in the electronic verification machine  108  then compares the two-bit pattern stored in the play spot code for each play spot area  424 A-P which has been previously determined by the detection circuitry of the electronic verification machine  108  as having been played. If two or more of the rubbed-off play spot areas have a value of “00” (i.e., “can&#39;t check locally”), the electronic verification machine  108  can not determine locally whether the ticket  422  is a winner of a high tier prize and if so, the redemption value of the ticket  422 . Thus, in the exemplary ticket  422  illustrated in FIGS. 36 and 37, if the bit pattern for any of the revealed play indicia  426 A-P matches the bit pattern for a second revealed play indicia  426 A-P, the redemption value of the ticket  422  equals the value of the matching play indicia  426 A-P. For example, if two of the revealed play indicia  426 A-P have a bit pattern equal to “11”, the redemption value of the ticket  422  is five dollars. The electronic verification machine  108  then informs the lottery agent of the redemption value of the ticket  422  via the display  180  or the printer  181  so that the ticket  50  can be paid.  
     [0269] If two of the entries in the table corresponding to the rubbed-off spots are “00”, however, the electronic verification machine  108  will not be able to locally determine the redemption value of the ticket  422 . Here the “00” bit pattern indicates that the rubbed-off play spots represent a high redemption value or that there may be more than one possible redemption value, for example, the value of all play indicia greater than five dollars. In this case, the electronic verification machine  108  accesses the ticket redemption file in the central computer  223  to determine the redemption value of the ticket  422 . In one arrangement the redemption file in the central computer  223  contains a record or a list for each ticket  422  in which the play indica value data are stored in association with a ticket identity number. The ticket identity number, for example accounting data contained in the bar code  428  or contained in a conventional validation number  78 , which uniquely identifies a ticket within a game is transmitted to the central computer  223  and can be used as an address to locate the record in the redemption file containing the indica or redemption values for that ticket. Thus, for example, the ticket redemption file for the ticket  422  includes play indicia value data which enables the central host computer  223  to determine whether or not any two of the rubbed-off spots has the same symbol (e.g., all $10, all $20, etc.). The central host computer  223  then transmits a signal to the electronic verification machine  108  indicating whether or not the ticket  422  is a winner, and if so, the redemption value of the ticket  422 . It should be noted that the functions of the central computer  223  and its associated redemption file as described above can be preformed by the computer in the processor board  220  of the electronic verification machine  108 .  
     [0270] As an alternative more than 2 bits can be used to represent each play spot. This will permit more or even all of the play spot areas to be validated by the electronic verification machine  108 . This embodiment reduces or eliminates calls to the central host computer  223 . However, this embodiment requires a longer play spot code and, hence, a longer bar code  428  if all the other fields in the bar code are kept at the same size as in the previous embodiment. As indicated above, the size of the bar code  80  can be reduced if a play spot code having a base larger than  10  is used.  
     [0271] A second approach to ticket validation involves using a validation file in the central computer  223  rather than encoding play indicia value data in the bar code  428  on the lottery ticket  422 . In this embodiment, the validation number only contains information related to the identity of the ticket, for example, the game number, pack number and ticket number. The validation number is read by the electronic verification machine  108  when, for example, the lottery agent inputs the validation number via the keyboard  178  of the electronic verification machine  108 . Alternatively, the validation number and game number can be stored on the ticket in a machine-readable format, for example, as part of the bar code  428  or even as a magnetic stripe. After the electronic verification machine  108  determines which play spot areas have been removed, the electronic verification machine  108  transmits the data as to which play spot areas have been removed along with the validation number to the central computer  223 . The central computer  223  contains the redemption or validation file which includes information corresponding to the ticket identification information for each ticket as well as a record with play indicia value data corresponding to each of the play spot areas  424 A-P on each ticket  422 . The central computer  223  then uses the ticket identification information to read the record corresponding to the ticket  422  and obtains the play indicia value data corresponding to the play spot areas  424 A-P that have been removed. If the number of the rubbed-off play spot areas  424 -P specified in the rules  432 , contain the same symbol, the ticket is a winner. The central computer  223  then determines the redemption value corresponding to the matching play indicia value data and sends authorization to the electronic verification machine  108  so that the redemption value can be paid. An additional advantage of this approach is that after a ticket has been presented for redemption, the records within the validation file which correspond to the ticket can be updated to reflect that the ticket has been verified by the electronic verification machine  108  and the central computer  223 . Consequently, the ticket  422  can be presented for redemption only one time and thereafter the validation file contains information indicating that the ticket has been previously paid.  
     [0272] VI. Stigmatization  
     [0273] There are cases where it is desirable to provide a positive indication that a document such as the lottery ticket  50  has been verified or validated by the electronic verification machine  108 . This process is termed stigmatization. One approach as described above in Section V. is to register each ticket  50  or document in a central computer that is connected to the electronic verification machine. Another approach is to stigmatize the ticket  50  or document itself.  
     [0274] Providing a hole puncher in the electronic verification machine  108  is one way to accomplish this object. In this case a hole is punched though a critical portion of the partial printed circuit after the verification process has taken place.  
     [0275] Printing a cancellation or void indication on the document by means of a printer such as a dot matrix printer (not shown) located in the electronic verifications machine  108  after verification is another approach that can be used.  
     [0276] Fuses located in the circuits printed on the document can be used to stigmatize or void the document. Here sufficient power is applied to the document such as the lottery ticket  50  by the electronic verification machine  108  to break for example one or more of the resistors  82 - 94  or blow selected fuses printed on the document. It should be noted that fuses of this nature can also be used to store specified information in the document. For example, if an array of fuses is printed on the document, information can be stored on the document by having the electronic verification machine  108  selectively burn certain fuses much as a PROM is programmed. This technique has applications other than lottery tickets such as an alternative to magnetic stripes on credit cards. Information burned in by blowing fuses can be far more difficult to alter than information contained in a magnetic stripe.  
     [0277] Coloration can also be used to stigmatize the document. In this case the document such as the lottery ticket  50  would also be printed with temperature sensitive ink. Power applied to the document by the electronic verification machine  108  would generate sufficient heat in the circuits printed on the document to change the color of at least a portion of the document.  
     [0278] VII. A Second Electronic Verification Machine and Verification Methods  
     [0279]FIGS. 38 and 39 illustrate a second embodiment of the invention, which is a second electronic verification machine  500 . The basic components of the electronic verification machine  500  are shown in block diagram form in FIG. 40. Included in the electronic verification machine  500  is a sensor array  502  which is connected to a digital processor board  504  by a set of sensor plate lines  506  and an excitation line  508 . A set of lines  510 - 514  provides signal inputs and outputs to a microcontroller  516  which forms part of the digital processor board  504 . A suitable microcontroller  516  is the Motorola MC68HC711E9CFN2 that includes a multiplexed 8 bit analog to digital converter (“A/D”)  517 . The electronic verification machine  500  also includes a bar code reader  518 , a stepper motor mechanism  520  and a set of three document position sensors  522  which are connected to the digital processor board  504  by a set of lines  524 - 528 . In the embodiment of the invention shown in FIG. 38, the digital processor board  504  is connected by a RS-232C serial digital interface  530  to a commercially available, microprocessor based, lottery retail terminal  532  that includes a random access memory  534 . A set of indicator lights  535  that in this embodiment include “power on,” “ready” and “jammed ticket” also form a part of the electronic verification machine  500 .  
     [0280]FIG. 39 is a sectioned side view of the electronic verification machine  500  which is primarily provided to illustrate a document interface and transport mechanism, indicated generally by  536 . Secured to a housing  538  is an upper document guide plate  540  and a lower document guide plate  542  that combine to form a channel  544  through which a document, such as a lottery ticket, can pass. The document (not shown) is placed in the upper opening  546  of the channel and drops down in response to gravity until it makes contact with a first set of pinch rollers  548  and  550  that extend through an aperture  552  and an aperture  554  in guide plates  540  and  542  respectively. Also included in the electronic verification machine  500  is a second set of pinch rollers  556  and  558  that extend through an aperture  560  and an aperture  562  in guide plates  540  and  542  respectively; a pressure roller  564  which extends through an aperture  566  in the lower guide plate  542 ; a set of three document edge detectors  568 ,  570  and  572  that are represented in FIG. 38 as the document position sensors  522 ; and the bar code reader  518  which is mounted in an aperture  574  of the lower guide plate  542 . A mirror  575  is mounted over the aperture  574  which makes it possible for the bar code reader  518  to read bar codes on either or both sides of the document as indicated by a dashed line  577 . In addition, the sensor array  502  is mounted on the upper guide plate  540  opposite the pressure roller aperture  566 . The pinch rollers  550  and  558  along with the pressure roller  564  are connected to the stepper motor  520  by a toothed belt (not shown) so that the rollers  550 ,  558  and  564  will all rotate at the same rate.  
     [0281] In operation, the document (not shown) is placed in the upper opening  546  of the channel and drops down in response to gravity until it makes contact with the first set of pinch rollers  548  and  550  which are normally not rotating. Meanwhile, the first edge detector  568  will provide an indication to the microcontroller  516  that a document is present in the channel formed by the guide plates  540  and  542  causing the stepper motor  520 , in response to a first pulse rate applied to the stepper motor  520  by the microcontroller  516 , to rotate at a first rate. When the document has been detected by the second edge detector  570  as emerging from the pinch rollers  550  and  548 , the microcontroller  516  will increase the rate of rotation of the stepper motor  520  resulting in the document being transported by the rollers  550 ,  564  and  558  at a rate of approximately 8 inches per second past the sensor array  502 . The second edge detector  570  also provides the mircrocontroller  516  with the precise location of the document so that the microcontroller  516  can initiate scanning of the document. The pinch rollers  548 ,  550 ,  556  and  558  are composed of a conventional elastomeric material and the pressure roller  564  is preferably composed of a closed cell polyurethane material in order to prevent this roller from absorbing or retaining any moisture that might be on the document. The purpose of the pressure roller  564  is to insure contact between the document and the sensor array  502 . After passing the sensor array  502 , the document will pass the bar code reader  518 , which will transmit the bar code information on the document to the microcontroller  516 , and the edge detector  572  will provide an indication to the microcontroller  516  that the document has exited the electronic verification machine  500 .  
     [0282] It should be noted that the configuration of the electronic verification machine  500  shown in FIG. 39 has a number of significant advantages including: a straight document path that minimizes the possibility of paper jams; positive control of the document by the stepper motor  520  in conjunction with the pinch rollers  550  and  558 ; the use of the pressure roller  564  to maintain contact of the document with the sensor array  502 ; and the use of the edge detectors  568 - 572  to provide the microcontroller  516  with information as to the location of the document in the electronic verification machine transport mechanism  536 . In addition, a self cleaning effect occurs because the document is in moving contact with the sensor array  502  and further more, the electronic verification machine  500  can readily accept documents of varying thickness.  
     [0283]FIG. 40 is a block diagram illustrating in more detail portions of the preferred embodiment of the sensor array  502 , the digital processor board  504  and the microcontroller  516  of FIG. 38. In this embodiment of the invention, the sensor array includes  14  sensor plates, designated by reference numeral  574 , and a rectangular excitation plate  576  mounted on a printed circuit board  578 . A set of 14 operational amplifiers, designated by reference numeral  580 , have their inverting inputs connected by the lines  506  to each one of the sensor plates  574 . Also connected to the inverting inputs and the outputs of the operational amplifiers  580  is a feedback line, indicated by reference numeral  582 , that includes a feedback resistor R f . The noninverting inputs of the operational amplifiers  580  are connected to ground as shown by lines  584 . The outputs of each of the operational amplifiers  580  are connected to one of two multiplexers  586  or  588  that in turn are connected by a pair of lines  590  and  592  to a pair of precision rectifiers  594  and  596 . The rectifiers  594  and  596  are connected to the analog to the digital input  517  of the microcontroller  516  via the lines  510  and  512 . Control is provided to the multiplexers  586  and  588  from the microcontroller  516  by the line  514 . In addition, the circuit of FIG. 40 includes a triangle wave voltage generator  598  that applies an AC excitation voltage over the line  508  to the excitation plate  576 . The voltage generator  598  can be controlled, in this case switched on or off, by the microcontroller  516  over a line  600 . For illustrative purposes, FIG. 40 also includes within a dashed line  602  an equivalent circuit of a document under test where C t1  represents the capacitance between the excitation plate  576  and the document; R t represents the resistance in the document between the excitation plate : 576  and the first sensor plate  574 ; and C t2  represents the capacitance between the document and the first sensor plate  574 .  
     [0284] One of the objects of the circuit shown in FIG. 40 is to scan the document under test  602 , such as a lottery ticket, for conductive material. Because the frequency and amplitude of the voltage generated by the triangular waveform voltage generator  598  are constant, the current I on the sensor plate  574  will be a square wave due to the relation I=C total dv/dt where C total  is the combined capacitances of C t1  and C t2 . As a result the voltage drop across the feedback resistor R f  will be a square wave having its amplitude proportional to the capacitance C total . The preferred frequency of the voltage generator is between 20 KHz and 150 KHz. Thus, the voltage output on lines  582  of the operational amplifiers  580  can be used to determine both the value of the coupling capacitance C total  and if there is conductive material between each of the sensor plates  574  and the excitation plate  576 . By using two multiplexers  586  and  588  and the rectifiers  510  and  512 , the microcontroller  516  can, in effect, sample the current on each of the sensor plates  574 , which would result from conductive material on the document  602 , thereby providing an indication of the presence or absence of conductive material across the document  602 . The stepper motor  520  of the electronic verification machine  500  advances the document  602  in discrete steps of approximately between 0.02 inches and 0.03 inches past the sensor array  502  and the microcontroller  516  applies the excitation signal to the excitation plate  576  for each step. In this manner the microcontroller  516  can be programmed to scan a predetermined portion or even the whole document  602  for conductive material as well as the values of the coupling capacitance C total .  
     [0285] Another very important capability of the circuit shown in FIG. 40, in addition to the determination of the presence of conductive material on the document under test, is that it can be used to determine an electrical signature of the document. For example, the electrical signature representing an electrical characteristic such as resistance can be measured as is discussed in more detail in connection with the circuits of FIGS. 18 and 41. Also, a measure of the total coupling capacitance C total  can be used as an electrical signature. As indicated above, if the voltage generator  598  generates a constant frequency triangular wave form, the current I on the sensor plate  574  will be linearly related to the capacitance C total  and therefore the coupling capacitance C total  itself can be measured. The total capacitance C total  depends on the characteristics of the document under test, such as the dielectric constant K of a dielectric material covering the conductive material or the thickness t of the dielectric material, while other factors including the size of the excitation plate  576  and the sensor plates  574  remain essentially constant. As a result, the value of the current I or changes in the current I can be used to measure a capacitive electrical signature of the document. For example, it would be possible in some cases to use a capacitive electrical signature to determine if a scratch-off coating covering conductive material on a lottery ticket has been removed.  
     [0286] In the embodiment of the sensor array shown in FIG. 40, the 14 sensor plates  574  are square with each side 0.10 inches in length and the excitation plate is 0.10 inches in width. The excitation plate  576  extends parallel to the linear array of sensor plates  574  and is located about 0.050 inches from the sensor plates  574 . Improved control of capacitance coupling is provided for by utilizing the pressure roller  564  of FIG. 39 to maintain the document  602  in direct physical contact with the sensor array  502 . Also, to insure adequate values of capacitance between the document  602  and the plates  574  and  576 , as represented by the capacitors C t1  and C t2 , the metal sensor and excitation plates  574  and  576  are coated with a material having a dielectric constant greater than 5. A suitable material for this coating is Kapton. In the event that a document interface is used where the document is not in contact with the sensor or excitation plates, is preferable that an air gap of less than 0.004 inches be maintained between the document and the plates. Also, in order to assure adequate values of sensed capacitance, it is preferable to have the rectangular excitation plate  576  several times larger in area than the sensor plates  574 .  
     [0287] It should be noted that one of the advantages of the verification or validation method described above, is that the ticket or document can be printed on a flexible substrate such as paper and because the conductive material can be in direct contact with the sensor array  502 , it is not necessary to apply a dielectric material over the document.  
     [0288] Illustrated in FIG. 41 is an alternate embodiment of a sensor circuit of the type shown in FIG. 18 that can be used to make measurements of the electrical signatures, such as resistance, of conductive material on documents. The circuit of FIG. 41 is suitable for use with the mechanical arrangement of the electronic verification machine  500  shown in FIG. 39 and is generally equivalent in function to the sensor array  502  and the processor circuits  504  shown in FIGS. 38 and 40. For purposes of explanation, the circuit diagram of FIG. 41 includes the document under test equivalent circuit  602  which has been described in connection with FIG. 40 and the equivalent elements from FIGS. 18, 38 and  40  carry the same reference numbers. As with the circuit of FIG. 18, an inductor  604 , for example having an inductance of 100 mH, is connected to each of a set of 5 sensor plates  606  in order to compensate, in phase, for the reactance resulting from the capacitance between the document  602  and the sensor plates  606  and a corresponding set of excitation plates  608 . The microcontroller  516  can be programmed to perform the same frequency sweeping functions as the mircrocontroller  224  described in connection with FIG. 18 and the processor circuits  504  can contain functional elements equivalent to the integrator (peak detector)  238 , the D/A converter  240  and the VCO  242 . Included in this circuit is a set of 5 excitation plates  608 . Although not shown in the schematic diagram of FIG. 41, the excitation plates  608  can be located between and aligned in a linear array with the sensor plates  606 . Although a single excitation plate  576  of the type shown in FIG. 40 can be used instead of the separate excitation plates  608 , the use of separate excitation plates  608  in this embodiment of the invention has the advantage of reducing distributed capacitances. Connected to each of the excitation plates  608  by a line  609  is a triangular wave voltage controlled oscillator (VCO)  610  in order to apply a triangularly shaped, AC excitation voltage or signal to the document under test. However, it should be noted that optimal performance of a resonant circuit can be achieved with a sinusoidal wave form instead of the triangular wave voltage generated by the generally less expensive VCO  610 . Also included in this circuit is a set of 5 operational amplifiers  612  connected in a voltage follower arrangement with the sensor plates  606 . Specifically, the noninverting inputs of each of the operational amplifiers  612  are connected, in this case, through the inductors  604  to the sensor plates  606  and to a resistor  614  that in turn is connected to ground. As a result, the output of each of the operational amplifiers  612 , on a set of lines  616  which are also connected to the inverting input of the operational amplifiers  612 , will be a voltage that represents the current flow through the resistor or resistance R t  of the document  602  resulting from the excitation signal on line  609 .  
     [0289] As indicated above, the circuit of FIG. 41 can use a control circuit  618 , which can include a microcontroller such as the microcontroller  516 , to perform an iterative resonance seeking algorithm to vary the frequency of the VCO  610  until the resonance of the LC circuit including the inductor  604  and the capacitance between plates  606  and  608  is found. The resulting voltage on lines  616 , which can be multiplexed, peak-detected and applied to the analog to digital input  517  of the microcontroller  516  in a manner similar to that shown in FIG. 40, represents the value of the resistance of a conductive material on a document. In this way it is possible to determine the electrical signature, for example the value of resistance, of conductive material located in a predetermined position on a document. Since it is possible to make accurate measurements of electrical signatures using the circuit of FIG. 41, this approach can be particularly useful for those documents, such as a lottery probability ticket of the type shown at  50  in FIG. 1, where particular accuracy may be important. Also, once the control circuit  618  has determined the resonance frequency, it can use a standard resonance frequency equation, such as C=25,330/f 2 L, to determine the coupling capacitance to the document since the inductance of the inductor  604  is known.  
     [0290] Another embodiment of a sensor array is illustrated in FIG. 42 where a document  620 , such as a lottery ticket, is inserted between an upper array of sensor plates  622  and a lower array of excitation plates  624 . This arrangement has the advantage of reducing the sensitivity of the system to displacement of the document  620  in a direction perpendicular to the plane of the document  620 .  
     [0291] As illustrated in FIGS.  43 - 45 , one of the advantages of the systems shown in FIGS.  38 - 40  is that it is possible to determine the location as well as the shape of conductive material on a document. As an example of how shapes on a document can be determined, a conventional instant lottery ticket  626  having a scratch-off coating  628 , shown partially broken away, covering a set of play indicia  630  is illustrated in FIG. 43. In this case the scratch-off coating includes a conductive material and one object of the system in this example is to determine what portion of the scratch-off coating has been removed as part of a ticket validating process. Contained in the terminal memory  534 , shown in FIG. 38, is a game signature map  632  in which a bit map or digital representation of the shape of the scratch-off coating  628  of the ticket  626  is stored. As previously described in connection with FIGS.  38 - 40 , the electronic verification machine  500  scans the ticket  626  for conductive material and the microcontroller  616  then transmits a digital representation of the location of the conductive material detected on the ticket  626  to a scanned data map contained in the memory  534 . At this point a microprocessor (not shown) in the lottery terminal  532  can compare the contents of the scanned data map  634  to the game signature map and if the data in the scanned data map meets certain predetermined criteria such as location, shape or percentage of expected removal of the scratch-off coating  628 , then a comparison signal is generated indicating that the ticket  626  has passed a verification or validation test. One method for representing verification criteria is by a vector. In the case of the ticket  626 , such a vector might have several bytes representing the starting address and the ending address of the game signature map  632  corresponding to where the scratch-off coating  628  can be expected along with another byte having a value that represents the minimum percentage of the scratch-off coating that constitutes an acceptably played ticket. As a practical matter, players often only scratch off a portion of the lottery ticket&#39;s scratch-off coating, so that, for example, an acceptable percentage for a particular type of played ticket might be 30%. Use of vectors of this type makes it especially easy to reprogram the terminal  532  for different types of lottery tickets or documents.  
     [0292] Another method of verifying a document such as a lottery ticket of the scratch-off type  626  is to utilize the capacitive signature of the ticket  626  as measured by the electronic verification machine  500 . Taking, for example, the ticket  626  which can include a uniform conductive material (not shown) applied beneath the scratch-off coating  628  and that is removable with the coating  628  of the type as described in U.S. Pat. No. 5,346,258, a measure of the signal to noise ratio between areas of the ticket  626  having the scratch-off coating  628  and the areas that do not, can provide a strong indication of validity. This method starts by determining a value for the coupling capacitance C total  for each location on the ticket  626  by measuring the current I on the sensor plates  574  using the circuit of FIG. 40. Then by taking the mean average T s  of the value of the coupling capacitance of the areas of the ticket  626  having the scratch-off coating  628  along with the mean average T p  of the other areas and dividing T s  by T p , a signal to noise ratio can be obtained. Here, T s  represents the signal and T p  represents the noise. Preferably, the value of T s  is calculated from only those coupling capacitance values that exceed a predetermined value such as 11 out of a maximum sensed value of 36. Computing this signal to noise ratio for an entire document such as the ticket  626  can provide an excellent indication of the validity of the document. It has been found, for instance, that lottery tickets of the type  626  will consistently produce signal to noise ratios of between 3.6 and 4.9.  
     [0293] One of the reasons that the above described signal to noise ratios can provide such an excellent indication of validity is that it measures an inherent electrical signature of a document that can be very difficult to forge. In the example above, the measured coupling capacitance C total  of the scratch-off areas  628  of the ticket  626  are a function of two independent factors: the thickness t and the dielectric constant K of the scratch-off coating  628 . Because C total  is equal to Kε 0 A/t where ε 0  is the permittivity of free space and A is the area of the capacitor plate  574 , a forger would have to almost exactly match both the thickness t and the dielectric constant K of the scratch-off coating.  
     [0294] In addition to lottery tickets, the scanning method as described above can be useful in the verification of a wide variety of documents. For instance, currency bills can be printed with conductive fibers or conductive inks located in predetermined locations. The electronic verification machine  500  can then be used to verify the authenticity of the bills by determining electrical signatures as well as the location or the amount of conductive material in the bills. Since the electronic verification machine  500  of FIGS.  38 - 40  can operate at relatively high speed, 8 to 10 inches per second, the verification of documents can be accomplished quickly and inexpensively.  
     [0295] Another application for the electronic verification machine  500  is in the validation of a pull-tab type lottery ticket  636  as shown in FIG. 46. The pull-tab ticket  636  is made up of a substrate  638  upon which play indicia, indicated by  640 , are printed. Laminated over the substrate  638  is a pull-tab stock member  642  having a number of perforated pull-tabs  644  located such that they cover the play indicia  640 . The underside or laminate surface of the pull-tab member  642  is printed with a layer of conductive ink, as indicated by reference numeral  646 , which forms a conductive plane and is not obvious to a player. In this type of ticket  636 , the conductive plane formed by the conductive ink layer  646  will be interrupted when a player removes one or more of the pull-tabs  644 .  
     [0296] Referring to FIG. 47, a pull-tab signature map  648  is graphically represented along side the pull-tab ticket  636 , with pull-tabs  644  shown as removed. As shown in this figure, the “0” bits in the signature map  648  correspond to positions of the pull-tab  644  on the ticket  638 . The remaining bits in the signature map  648  are set to “1.” As a result, the signature map  648  provides a digital representation of the location of the pull-tabs  644  along the center line of the pull-tab ticket  636 . The signature map  644  can be stored in the memory  534  of the lottery terminal  532  or in the case where a simplified version of the type of electronic verification machine  500  of FIG. 38 is to be used, the signature map  644  can be stored in the microcontroller memory  516  or its equivalent.  
     [0297] A simplified sensor array  650 , which can be used in the electronic verification machine  500  to validate the pull-tab ticket  636 , is shown in FIG. 48 as positioned over the pull-tab ticket  636 . The sensor array  650  includes a sensor plate  652  located between a pair of excitation plates  654  and  656  such that the sensor plate  652  is aligned with the center line of the pull-tab ticket  636 . The circuits (not shown) connected to the sensor and excitation plates  652  and  654  are substantially the same and operate in the same manner as the circuits in FIG. 40. In validating the pull-tab ticket  636 , the ticket  636  is scanned along its center line, in the direction indicated by an arrow  656 , by the sensor plate  652  and its associated circuity in the electronic verification machine  500 . If, for example, the output of sensor plate  652  is equivalent all “0”s, then the ticket  636  does not contain conductive ink and, as such, can be considered a forgery, perhaps a photocopy. Then by comparing the sensor plate  652  output to the signature map  644  it is possible to determine how many, if any, of the pull-tabs  644  have been opened.  
     [0298] VIII. A Second Probability Game Ticket Configuration.  
     [0299] FIGS.  49 - 50  and  52 - 72  show a second embodiment of a probability game ticket  700 , which is the preferred embodiment to be used in conjunction with the sensor array  502  of the electronic verification machine  500 , shown in FIGS.  38 - 40 . FIG. 49 presents the finished appearance of the ticket  700 . The ticket  700  is printed on a substrate  702 , such as card stock or paper, and has three portions: a display graphics portion, shown generally at  704 , a play field portion, shown generally at  706 , and a ticket identification portion, shown generally at  708 . As with the previous ticket  50 , the display graphics portion  704  includes a variety of printed information such as the name  710  of the game, rules  712  for playing the game, and customized art work  714 . The play field portion  706  includes a group of play spot areas  716 A-H which are printed as overprint layers. The play field portion  706  can also include play spot graphics  718  which help to further visually delineate each play spot area  716 A-H. Each play spot area  716 A-H conceals a play indicia  720 A-H (shown in FIG. 61). For example, play spot area  716 A has been removed to reveal the underlying play indicia  720 A. The ticket identification portion  708  includes a void-if-removed area  722  which is printed as an overprint layer. The void-if-removed area  722  can include overprint graphics  724 . The void-if-removed area  722  conceals a validation number  726  (shown in FIG. 61) which contains information that can be used in validating the ticket  700 . The ticket identification portion  708  also includes an inventory control number  728  and a machine-readable bar code  730 . Similar to the bar code  80  of the first ticket  50 , the bar code  730  can include information related to the validation number  726  (shown in FIG. 61), to the pack and ticket numbers for the ticket  700  and to the redemption values of the play indicia  720 A-H. The bar code  730  thus serves as a ticket identification indicia for the ticket  700 .  
     [0300]FIG. 50 is a plan view of various circuit elements which are used in determining the authenticity and integrity of the ticket  700 . The ticket  700  includes two general types of circuit elements which are used in association with the play indicia  720 A-H and with the bar code  730 . The first type of circuit element consists of individual indicia circuit elements  732 A-H which are used to determine the presence of the play indicia  720 A-H as well as the integrity of each of the underlying play indicia  720 A-H. Each of the indicia circuits  732 A-H includes a first capacitive pick-up area, generally denoted as  734 , a second capacitive pick-up area, generally denoted as  736 , and a resistive element, generally denoted as  738 , that is connected to and extends between the first and second capacitive pick-up areas  734  and  736 . Thus, for example, the indicia circuit element  732 A includes the first capacitive pick-up area  734 A, the second capacitive pick-up area  736 A and the resistive element  738 A. Similarly, the indicia circuit element  732 B includes the first capacitive pick-up area  734 B, the second capacitive pick-up area  736 B, and the resistive element  738 B. The resistive elements  738 A-H are printed in a serpentine pattern so as to cover most of the play indicia  720 A-H. As explained in more detail with reference to FIGS.  69 - 70 , each of the indicia circuit elements  732 A-H is associated with one of the underlying play indicia  720 A-H. Thus, for example, the indicia circuit element  732 A is associated with the play indicia  720 A, shown in FIG. 49. The individual indicia circuit elements  732 A-H are printed on the ticket  700  so that at least a portion of each indicia circuit  732 A-H overlies one of the individual play indicia  720 A-H. In the preferred embodiment, the resistive element  738  of the indicia circuit elements  732  are printed on the ticket  700  to overlie one of the play indicia  720 . Moreover, in the preferred embodiment the capacitive pick-up areas  734  and  736  of the indicia circuit elements  732  are printed on the ticket  700  so that the capacitive pick-up areas  734  and  736  do not overlie any of the play indicia  720 . Thus, for example, the resistive element  738 A of the indicia circuit element  732 A is printed in the ticket  700  to overlie the play indicia  720 A and while the capacitive pick-up areas  734 A and  736 A of the indicia circuit element  732 A are printed on the ticket  700  so that the capacitive pick-up areas  734 A and  736 A are spaced-apart from the play indicia  720 A and do not overlie the play indicia  720 A or any of the other play indicia  720 B-H.  
     [0301] The individual indicia circuit elements  732 A-H capacitively couple with the sensor array  502  of the electronic verification machine  500  when the ticket  700  is placed in the opening  546  of the electronic verification machine  500  and is moved through the electronic verification machine by the stepper motor  520 , the pinch rollers  548 ,  550 ,  556 ,  558 , and the pressure roller  564 , as described with reference to FIGS.  38 - 40 . Specifically, the first capacitive pick-up areas  734 A-H capacitively couple with the sensor plates  574  of the sensor array  502  and therefore serve as sensor capacitive pick-up areas for the indicia circuit elements  732 A-H. In addition, and the second capacitive pick-up areas  736 A-H capacitively couple with the excitation plate  576  of the sensor array  502  and therefore serve as excitation capacitive pick-up areas for the indicia circuit elements  732 A-H. Consequently, the dimensions and positions of the capacitive pick-up areas  734 A-H and  736 A-H are determined by the dimensions and positions of the excitation plate  576  and the sensor plates  574  of the sensor array  502 . In the preferred embodiment, the width of both the first and second capacitive pick-up areas  734 A-H and  736 A-H is on the order of 0.26 inches, the height of the first capacitive pick-up areas  734 A-H is about 0.05 inches, and the height of the second capacitive pick-up areas  736 A-H is on the order of 0.10 inches. In addition, the first capacitive pick-up areas  734 A-H are longitudinally spaced-apart from the second capacitive pick-up areas  736 A-H by a predetermined distance which, in the preferred embodiment is about 0.07 inches. Moreover, each of the individual indicia circuit elements, for example, indicia circuit element  734 B, is longitudinally spaced apart from adjacent indicia circuit elements, for example, indicia circuit elements  732 A and  732 C, by a predetermined distance. The configuration of the indicia circuit elements  732 A-H offer several advantages. First, the individual indicia circuit elements  732 A-H provide discreet electrical signatures for each of the play spot areas  716 A-H and associated underlying play indicia  720 A-H. Consequently, the indicia circuit elements  732 A-H can be used to determine the presence as well as the integrity of the individual play spot areas  716 A-H and the associated underlying play indicia  720 A-H. In addition, each of the indicia circuit elements  732 A-H is spatially isolated from other circuit elements. Consequently, stray electrical noise is minimized or eliminated.  
     [0302] As explained in more detail below, portions of the indicia circuit elements  732 A-H are removed when the play spot areas  716 A-H are removed to reveal the play indicia  720 A-H. Consequently, the ink used to print the indicia circuit elements  732 A-H should have a reduced adhesiveness so that the portions of the indicia circuit elements  732 A-H are readily removed from the ticket  700 . In addition, the ink used to print the indicia circuit elements  732 A-H should also be fairly conductive. In the presently preferred embodiment of the invention, the sheet resistivity of the ink used to print the indicia circuit elements  732 A- 732 H is on the order of 2 KΩ/□. Table 4 describes the presently preferred formulation for the ink used print the indicia circuit elements  732 A- 732 H.  
               TABLE 4                          Ink Formulation For The Indicia Circuit Elements 732A-732H                             material   wt %                                         Polyamide resin   1.75           Dimethylethanol amine   0.25           Ammonium Hydroxide   0.25           Conductive Carbon Black   13.00           Polyethylene/PTFE wax   1.50           Silicone paste   1.25           Acrylic synthetic pigment   4.00           Colloidal acrylic   9.00           Ethyl Alcohol   2.00           Styrenated acrylic emulsion (high T g )   8.25           Styrenated acrylic emulsion (low T g )   16.45           Silicone-based surfactant   0.50           Water   41.80                      
 
     [0303] An alternative ink formulation for the ink used to print the indicia circuit elements  732 A- 732 H is given in Table 5. This ink has a lower sheet resistivity than that of the ink described in Table 4, on the order of about 1 KΩ/□.  
               TABLE 5                          Alternative Ink Formulation For The Indicia Circuit Elements       732A-H                             material   wt %                                         water   41.8           Dispersant (W-22)   4.8           Dimethylethanolamine   0.25           Defoamer (RS-576)   0.4           Carbon Black   15           wetting agent (BYK 348)   0.5           EVCL Emulsion Vancryl 600   3           Ammonium Hydroxide   0.25           DC-24 Silicone Emulsion   2           Styrenated Acrylic Varnish (J678)   5           Plasticizer 141   2           Styrenated Acrylic Emulsion 7830   20           Ethanol   5                      
 
     [0304] The second general type of circuit element is an integrity circuit element  740  that is used to determine the authenticity and integrity of the ticket identification indicia, such as the bar code  730 . The integrity circuit element  740  includes a first capacitive pick-up area  742  that is shaped and sized to capacitively couple with one of the sensor plates  574  of the sensor array  502 . The integrity circuit element  740  also includes a second capacitive pick-up area  744  that is shaped and positioned to capacitively couple with the excitation plate  576  of the sensor array  502 . Both the first and second capacitive pick-up areas  742  and  744  are printed entirely within the ticket identification portion  708  of the ticket  700  and, as explained in more detail below, underlie at least a portion of the ticket identification indicia, such as the bar code  730 . The ticket integrity circuit  740  also includes a resistive element  746  that is connected to and extends between the first and second capacitive pick-up areas  742  and  744 . The resistive element  746  is printed on the ticket  700  so that a portion  748  of the resistive element  746  is located within the play field portion  706  of the ticket  700  and is shown as encompassing indicia circuit elements  732 D and  732 H. The integrity circuit element  740  provides a discreet electrical signature for the ticket identification indicia, such as the bar code  730 , and thus can be used to determine the authenticity and integrity of the ticket identification indicia. For example, if an attempt is made to replace the bar code  730  by cutting the ticket  700 , the resistive element  746  would also be cut and thus detectable by the electronic verification machine  500 .  
     [0305] The ticket  700  can include additional data circuits, generally denoted as  750 , which can be used to provide additional ticket authenticity and integrity information. The data circuits  750  include first capacitive pick-up areas  752  and second capacitive pick-up areas  754  that are positioned and shaped to capacitively couple with one of the sensor plates  574  and with the excitation plate  576 , respectively, of the sensor array  502 . The data circuits  750  also include data tracks  756  that spans between the capacitive pick-up areas  752  and  754 . The data tracks  756  are used to electrically store data in a binary form. For example, when the data tracks  756  include a conductive material the data tracks can encode a bit-on or “1” signal. Alternatively, when the data tracks  756  do not include a conductive material the data tracks  756  can encode a bit-off or “0” signal. As shown in FIG. 50, the ticket  700  preferably includes at least two data circuits,  750 A and  750 B, both of which are printed within the ticket identification portion  708 . By including two data circuits  750 A and  750 B, the ticket can store four separate binary codes, e.g., 11, 10, 01, and 00. As shown in FIG. 50, the data track  756 A of the data circuit  750 A does not include a conductive material and so encodes a bit-off or “0” signal while the data track  756 B of the data circuit  750 B includes conductive material and so encodes a bit-on or “1” signal. The binary code produced by the data circuits  750 A and  750 B, when used in conjunction with additional information stored elsewhere on the ticket  700 , for example, in the validation number  726 , can provide at least partial ticket authenticity and integrity information. The ink used to print the integrity circuit element  740  and the data circuit elements  750 A-B should be fairly conductive. Table 11, in Section XII.B. (below) describes the presently preferred formulation for the ink used to print the integrity circuit elements  740 . The ink described in Table 11 has a sheet resistivity of less than 5 KΩ/□. Table 1 presents an alternative ink formulation for printing the integrity circuit elements. The ink described in Table 1 has sheet resistivity of about 3 MΩ/□.  
     [0306] It should be noted that the two general types of circuit elements, the indicia circuit elements  732 A-H and the integrity circuit element  740 , are actually printed on the ticket  700  as separate layers. In addition, the ticket  700  includes several other layers that are used to generate the finished form of the ticket  700  shown in FIG. 49. FIGS.  51 - 72  illustrate the sequence and configurations of the layers which form parts of the ticket  700 . The ticket  700  is preferably printed by an intaglio method. A gravure printing method is especially preferred as it allows for the widest range of ink and coating formulations, although other intaglio printing methods can be used. The ticket  700  can also be printed by screen printing, relief printing, planographic printing, letterpress, and flexographic printing. However, as noted a gravure printing process is preferred for printing the ticket  700 . FIG. 51 presents a schematic diagram of a gravure printing press  760  which is suitable for printing the ticket  700 . The press  760  has fifteen printing stations  762 - 790 , each of which prints one layer on the ticket  700 , and one ink jet printer  792  that prints the play indicia  720 A-H, the validation number  726 , the inventory control number  728 , and the bar code  730 . The first print station  762  prints a first layer  794  on the ticket  700 . The first layer  794  is an opaque blocking layer that helps to protect the play indica  720 A-H and the circuit elements  732 A-H,  740 ,  750 A, and  750 B, from surreptitious detection by candling.  
     [0307] In order that the circuit elements such as  732 A-H,  740 ,  750 A or  750 B can be detected, the first opaque blocking layer  794 , as well as any other layer on the ticket, should be relatively non-conductive as compared to the conductivity of the circuit elements  732 A-H,  740 ,  750 A or  750 B. Otherwise, the layer  794  would tend to interfere with the detection of the electrical signatures of the circuit elements  732 A-H,  740 ,  750 A or  750 B. This is especially the case with the capacitive pick-up areas such as  734 A-H and  736 A-H and in particular with respect to the capacitive pick-up areas  734 A-H that serve in this embodiment as sensor capacitive pick-up areas. It has been found that a relatively conductive layer under the capacitive pick-up area  734  can result in a noise spike, making it difficult for the electronic verification machine  500  to accurately the presence or signature of the resistive element  738 . Although it is possible to detect the presence of the resistive elements  738 A-H and  746  using an electronic verification machine of the type shown at  500  where the conductivity of the circuit elements such as  732 A-H,  740 ,  750 A and  750 B is only twice the conductivity of an adjacent layer such as the lower blocking layer  794 , it is desirable that the difference in conductivity be at least one order of magnitude or 10 dB and more preferably, two to three orders of magnitude or 20 to 30 dB. Therefore, it is considered preferable that, in order to reduce the signal to noise ratio in scanning the circuit elements such as  732 A-H,  740 ,  750 A and  750 B, that the layer  794  appear to be substantially nonconductive in comparison to the circuit elements  732 A-H,  740 ,  750 A and  750 B. By increasing the difference in conductivity between the circuit elements such as  732 A-H,  740 ,  750 A and  750 B and the layer  794  it is possible to reduce the manufacturing tolerances of both the electronic verification machine  500  and the ticket  700 . This consideration is significant when documents and verification machines are being produce in large volumes. In particular where the lottery tickets  700  are printed in the millions and are subject to various types of abuse such as bending and crumpling, the difference in conductivity between the circuit elements  732 A-H,  740 ,  750 A and  750 B and the layer  794  is preferably three orders of magnitude or  30  dB. Thus, in the preferred embodiments of the electronic verification machine  500  and the ticket  700 , where the blocking layer  794  is a continuous layer underlying all of the circuit elements  732 A-H,  740 ,  750 A and  750 B, the desired relationship between the sheet resistivity (ρs (LBL) ) of the lower blocking layer  794  and the sheet resistivity (ρs (CE) ) of the circuit elements  732 A-H,  740 ,  750 A, and  750 B is at least two orders of magnitude as illustrated by the equation:  
     ρs (LBL) ≧1000 ρs (CE)    
     [0308]FIG. 52 illustrates the preferred embodiment of the lower blocking layer  794  when the lower blocking layer  794  has a sheet resistivity that is at least one thousand times greater than the sheet resistivities of the circuit elements  732 A-H,  740 ,  750 A, and  750 B. In this embodiment, the lower blocking layer  794  is printed as a continuous, substantially opaque layer  796  that completely overlies the play field portion  706  and the ticket identification portion  708  of the ticket  700 . The lower blocking layer  794  can, however, be printed with materials that have a lesser difference in conductivity relative to the circuit elements  732 A-H,  740 ,  750 A, and  750 B as long as the configuration of the lower blocking layer  794  electrically isolates at least portions of the circuit elements  732 A-H,  740 ,  750 A, and  750 B from the lower blocking layer  794 . For example, FIG. 53 illustrates an alternative configuration of the lower blocking layer  794  which is printed as a barred layer  798  that includes laterally spaced-apart strips  800 A and  800 B which are printed with a material which is minimally conductive relative to the material used to print the circuit elements  732 A-H,  740 ,  750 A, and  750 B. The spaced-apart strips  800 A and  800 B are substantially opaque and longitudinally span the play field portion  706  and the ticket identification portion  708  of the ticket  700 . The spaced-apart strips  800 A and  800 B define channels  802 A and  802 B for the resistive elements  738 A-H of the indicia circuit elements  732 A-H. The space between the strip  800 A and the interface  804  between the play field portion  706  and the display portion  704  and the space between the strips  800 A and  800 B define channels  806 A and  806 B for the capacitive pick-up areas  734 A-H and  736 A-H of the indicia circuit elements  732 A-H, for the capacitive pick-up areas  742  and  744  of the integrity circuit element  740 , and for the capacitive pick-up areas  752 A-B and  754 A-B of the data circuits  750 A-B. The configuration of the lower blocking layer  794  thus electrically isolates the capacitive pick-up areas  734 A-H,  736 A-H,  742 ,  744 ,  752 A-B, and  754 A-B of the various circuit elements  732 A-H,  740 ,  750 A, and  750 B from the minimally conductive strips  800 A and  800 B. FIG. 54 illustrates another embodiment of the lower blocking layer  794  which includes a patterned layer  808  that is printed with a material that is minimally conductive relative to the circuit elements  732 A-H,  740 ,  750 A, and  750 B. The patterned layer  808 , which, is substantially opaque, spans both the play field and ticket integrity portions  706  and  708  of the ticket  700  and defines several apertures  810 A-H,  812 ,  314 A, and  814 B which electrically isolate portions of the circuit elements  732 A-H,  740 ,  750 A, and  750 B. Specifically, the apertures  810 A-H are positioned and shaped to electrically isolate the first capacitive pick-up areas  734 A-H of the indicia circuit elements  732 A-H, the aperture  812  is positioned and shaped to electrically isolate the first capacitive pick-up  742  of the ticket integrity circuit  740 , and the apertures  814 A and  814 B are positioned and shaped to electrically isolate the first capacitive pick-up areas  752 A and  752 B of the data circuits  670 A-B. As previously noted, the first capacitive pick-up areas  734 A-H,  742 , and  752 A-B serve a sensor capacitive pick-up areas when the ticket  700  is read by the electronic verification machine  500 . Table 10, in Section XII.B. (below) describes the presently preferred formulation for an ink used to print the lower blocking layer  794 . The ink described in Table 10 has a sheet resistivity which is greater than about 20 MΩ/□. An alternative formulation for the ink used to print the lower blocking layer  794  is given in Table 6. The formulation in Table 6 is particularly useful for printing the lower blocking layer  794  either as the barred layer  798  or as the patterned layer  808 .  
               TABLE 6                          Ink Formulation For The Lower Blocking Layer 794                             Material   wt %                       Predesol Carbon Black 1649V   25           (KVK USA, Inc.)           VCMA   10           methyl-ethyl ketone   65                      
 
     [0309] It should be noted that since one of the functions of the lower blocking layer  794  is to obscure the play indicia  720 A-H and the circuit elements  732 A-H,  740 , and  750 A-B, it is desirable that the blocking layer  794  be a opaque as possible. One way to achieving a sufficiently opaque layer is to use inks that contain black pigments or other dark pigments in order to mask the circuit elements circuit elements  732 A-H,  740 , and  750 A-B. Thus, it is convenient to use carbon or carbon black in the ink used for the layer  794 . Using carbon black normally will result in an ink with a sheet resistivity less than would be the case with a basically non-conductive material such as the paper substrate  702 . However, the ink formulation presented in Table 6 above does provide a relatively high sheet resistivity which, in this case, is greater than 20 MΩ/□. Thus, as noted above, this ink formulation is suitable for printing the lower blocking layer  794  provided at least portions of the circuit elements  732 A-H,  740 ,  750 A, and  750 B are electrically isolated from the layer  794 , for example, by printing the lower blocking layer  794  as the barred layer  798  having spaced-apart strips  800 A-B or by printing the lower blocking layer  794  as the patterned layer  808  having the apertures  810 A-H,  812 ,  814 A, and  814 B.  
     [0310] The second printing press station  764  prints the second layer  826  which consists of the ticket integrity circuit  740  and the data circuits  750 A-B. The appearance of the ticket  700  at this point depends on the form of the lower blocking layer  794 . FIG. 55 shows the ticket  700  when the lower blocking layer  794  is printed as the continuous, substantially non-conductive layer  796 . Both of the data circuits  750 A and  750 B are printed over the first layer  796  within the ticket identification portion  708  of the ticket  700 . The first capacitive pick-up area  742  and the second capacitive pick-up area  744  of the integrity circuit element  740  are also printed within the ticket identification portion  708  over the layer  796 . The resistive element  746 , which is connected to and extends between the capacitive pick-up areas  742  and  744  of the integrity circuit element  740 , is printed on the layer  796  so that the portion  748  of the resistive element  746  is located within the play field portion  706  of the ticket  700 . FIG. 56 shows the ticket  700  when the lower blocking layer  794  is printed as the barred layer  798 . The first capacitive pick-up area  742  of the integrity circuit element  740  is printed in the ticket identification portion  708  and is located within the channel  806 A. The first capacitive pick-up area  742  thus is not printed over either of the strips  802 A or  802 B and is actually printed on the substrate  702  of the ticket  700 . Similarly, the capacitive pick-up areas  752 A and  754 A of the data circuit element  750 A and the capacitive pick-up areas  752 B and  754 B of the data circuit element  750 B are printed in the ticket identification portion  708  and are located within the channel  806 B. The capacitive pick-up areas  752 A,  754 A,  752 B, and  754 B of the data circuit elements  750 A and  750 B are thus printed on the substrate  702  of the ticket  700 . Consequently, because the capacitive pick-up areas  742 ,  752 A,  754 A,  752 B, and  754 B are printed on the substrate  702 , the capacitive pick-up areas  742 ,  752 A,  754 A,  752 B, and  754 B are electrically isolated from the layer  798 . The second capacitive pick-up area  744  is printed within the ticket identification portion  708  over the strip  800 B and thus is located in the channel  802 B. The resistive element  746 , which is connected to and extends between the capacitive pick-up areas  742  and  744  of the integrity circuit element  740 , is printed on the ticket  700  so that the portion  748  of the resistive element  746  is located within the play field portion  706  of the ticket  700 . FIG. 57 shows the ticket  700  when the lower blocking layer  794  is printed as the patterned layer  808 . The first capacitive pick-up area  742  of the integrity circuit element  740  is printed in the ticket identification portion  708  and is located within the aperture  812 . The first capacitive pick-up area  742  thus is not printed over the patterned layer  808  and is actually printed on the substrate  702  of the ticket  700 . Similarly, the capacitive pick-up area  752 A of the data circuit element  750 A and the capacitive pick-up area  752 B of the data circuit element  750 B are printed in the ticket identification portion  708  and are located within the apertures  814 A and  814 B, respectively. The capacitive pick-up areas  752 A and  752 B of the data circuit elements  750 A and  750 B are thus printed on the substrate  702  of the ticket  700 . Consequently, because the capacitive pick-up areas  742 ,  752 A, and  752 B are printed on the substrate  702 , the capacitive pick-up areas  742 ,  752 A, and  752 B are electrically isolated from the layer  808 . The second capacitive pick-up area  744  of the integrity circuit element  740  and the second capacitive pick-up areas  754 A and  754 B of the data circuits  750 A and  750 B are printed directly over the patterned layer  808 , within the ticket identification portion  708  of the ticket  700 . The resistive element  746 , which is connected to and extends between the capacitive pick-up areas  742  and  744  of the integrity circuit element  740 , is printed on the ticket  700  so that the portion  748  of the resistive element  746  is located within the play field portion  706  of the ticket  700 .  
     [0311] The third printing press station  766  prints the third layer  818  (shown in FIG. 58) which is a masking layer that masks the lower blocking layer  794  and prevents visual interference from the lower blocking layer  794  when a user inspects the play indicia  720 A-H (shown in FIG. 61). As shown in FIG. 58 the masking layer  818  is printed as a continuous layer that covers both the play field portion  706  and the ticket identification portion  708  of the ticket  700 . In order not to interfere with the electrical signatures of the circuit elements  732 A-H,  740 ,  750 A, and  750 B, the electrical conductivity of the masking layer  818  should be significantly less than the electrical conductivity of the circuit elements  732 A-H,  740 ,  750 A, and  750 B. In the preferred embodiment, the sheet resistivity of the masking layer  818  is greater than 10 8  Ω/□. A suitable formulation for the masking layer  818  is given in Table 7.  
               TABLE 7                          Ink Formulation For The Masking Layer 818                             material   wt %                                         Predasol rutile white 1300-PA   33.33           versamide 940 resin   22.22           ethanol   22.225           heptane   22.225                      
 
     [0312] The fourth printing station  768  prints the fourth layer  820  which is a primer layer that provides a suitable surface for printing the play indicia  720 A-H (shown in FIG. 61). As shown in FIG. 59, the primer layer  820  is printed as a continuous layer that covers both the play field portion  706  and the ticket integrity portion  798  of the ticket  700 . In order not to interfere with the electrical signatures of the circuit elements  732 A-H,  740 ,  750 A, and  750 B, the electrical conductivity of the primer layer  820  should be significantly less than the electrical conductivity of the circuit elements  732 A-H,  740 ,  750 A, and  750 B. In the preferred embodiment, the sheet resistivity of the primer layer  820  is greater than 10 8  Ω/□. Printing stations  770 - 774  provide the features printed in the display portion  704  of the ticket  700  which, as shown in FIG. 60, include the name of the game  710 , the rules for playing the game  712 , and the customized art work  714 . The ink jet station  792  prints the play indicia  720 A-H, the validation number  726 , the inventory control number  728  and the bar code  730 . As shown in FIG. 61 the play indicia  720 A-H are printed directly on the primer layer  820  within the play field portion  706  of the ticket  700 . The validation number  726 , the inventory control number  728  and the bar code  730  are also printed directly on the primer layer  820  but are located within the ticket identification portion  708  of the ticket. Station  776  prints the back  822  of the ticket  700  which, as shown in FIG. 62, can include additional information  824  concerning the game.  
     [0313] Station  778  prints the fifth layer  826  which is a seal coat layer that protects the play indicia  720 A-H and the validation number  726  against abrasion. FIG. 63 illustrates the seal coat layer  826  which is printed on the ticket  700  so that the layer  826  covers all of the primer layer  820  within the play field portion  706  and so that the seal coat layer  826  covers the validation number  726  within the ticket identification portion  708  of the ticket. In order not to interfere with the electrical signatures of the circuit elements  732 A-H,  740 ,  750 A, and  750 B, the electrical conductivity of the seal coat layer  826  should be significantly less that the electrical conductivity of the circuit elements  732 A-H,  740 ,  750 A, and  750 B. In the preferred embodiment, the sheet resistivity of the seal coat layer  826  is greater than 10 8  Ω/□. A suitable formulation for the seal coat layer  826  is given in Walton, U.S. Pat. No. 4,726,608.  
     [0314] The next layer is a release coat layer, generally denoted as  828 , that is printed by the station  780 . The release coat layer  828  is not continuous but instead in this embodiment consists of discreet layer portions  828 A- 828 H that are associated with the play indicia  720 A and a discrete layer portion  828 I that is associated with the validation number  726 . Thus, as shown in FIG. 64, the release coat layer  828  is printed on the seal coat layer  826  so that the release coat layer portion  828 A covers the play indicia  720 A. Similarly, the release coat layer portion  828 C covers the play indicia  720 C and the release coat layer portion  828 F covers the play indicia  720 F. In addition, the release coat layer portion  828 I covers the validation number  726 . The release coat  828  serves two general functions. First, the release coat  828  assures that layers which overlie the play indicia  720 A-H and the validation number  726  can be removed to reveal the play indicia  720 A-H and the validation number  726 . In addition, as explained with reference to FIG. 75, the discrete release coat portions  828 A-H help to ensure that the electrical signatures of the indicia circuit elements  732 A-H change when the layers overlying the play indicia  720 A-H are removed to reveal the play indicia  720 A-H. In order not to interfere with the electrical signatures of the circuit elements  732 A-H,  740 ,  750 A, and  750 B, the electrical characteristics of the release coat layer  828  should be significantly less than the electrical conductivity of the circuit elements  732 A-H,  740 ,  750 A, and  750 B. In the preferred embodiment, the sheet resistivity of the release coat layer  828  is greater than 10 8  Ω/□. However, since the release coat layer  828  does not contact any of the capacitive pick-up areas  734 A-H.  736 A-H,  742 A-H,  744 A-H,  752 A-B, and  754 A-B, a lesser sheet resistivity, for example about 10 7  Ω/□, would be acceptable. A suitable formulation for the release coat layer  828  is given in Walton, U.S. Pat. No. 4,726,608.  
     [0315] Station  782  prints the next layer which is an opaque upper blocking layer  830  that helps to protect the play indicia  720 A-H, the validations number  726  and portions of the circuit elements  732 A-H,  740 ,  750 A, and  750 B against surreptitious detection by candling. The preferred embodiment of the upper blocking layer  830  has a sheet resistivity that is at least about 1000 times greater than the sheet resistivity of the circuit elements  732 A-H,  740 ,  750 A, and  750 B. Consequently, in the preferred embodiment the upper blocking layer  830  does not interfere with the electrical signatures of the circuit elements  732 A-H,  740 ,  750 A, and  750 B and there is no need to electrically isolate the circuit elements  732 A-H,  740 ,  750 A, and  750 B from the upper blocking layer  830 . Thus, shown in FIG. 65, in the preferred embodiment the upper blocking layer  830  is printed as a continuous layer  832  that overlies the play field portion  706  of the ticket  700  and overlies the validation number  726  within the ticket integrity portion of the ticket  700 . The play indicia  720 A and the associated release coat portion  828 A are shown in phantom for reference. A presently preferred formulation for the ink used to print the upper blocking layer  830  is given in Table 8. The ink formulation described in Table 8 has a sheet resistivity greater than 1 GΩ/□.  
               TABLE 8                          Ink Formulation For The Upper Blocking Layer 830                             Material   wt %                                         non-conductive carbon black dispersion (35% carbon)   23.71           Normal propyl acetate   21.85           Heptane   25.94           Rubber block copolymer   6.25           Calcium carbonate   8.00           Maleic rosin ester resin   1.50           Titanium dioxide   7.00           Silicone paste   1.50           Diacetone alcohol   0.50           Terpene phenolic resin   0.75           PE/PTFE wax blend   3.00                      
 
     [0316] The upper blocking layer  830  can also be printed with materials that have a lesser difference in conductivity relative to the circuit elements  732 A-H,  740 ,  750 A, and  750 B as long as the configuration of the layer  830  electrically isolates at least portions of the indicia circuit elements  732 A-H. Another suitable ink for the upper blocking layer  830  is given in Table 9.  
               TABLE 9                          Ink Formulation For The Upper Blocking Layer 830                             material   wt %                                         Heptane   34.1           Normal Propyl Acetate   30           Rosin Ester Resin 3330   10.2           Silicone Dispersant BYK 163   0.7           Carbon Black 350   13           Rubber Copolymer D 1107   9.2           Calcium Carbonate   1.7           Polyethylene/PTFE wax blend   1                      
 
     [0317] Similar to the lower blocking layer  794 , one of the functions of the upper blocking layer  830  is to obscure the play indicia  720 A-H and the circuit elements  732 A-H. Consequently, the upper blocking layer  830  should be as opaque as possible, a goal which is conveniently obtained by using carbon black or other dark pigments in the ink used to print the upper blocking layer  830 . However, the presence of carbon black in the ink used to print the upper blocking layer  830  can result in an ink formulation that is somewhat conductive. However, the ink formulation in Table 9 does provide a relatively high sheet resistivity which, in this case, is greater than about 20 MΩ/□. In addition, the ink formulation in Table 9 has a reduced graphic adhesiveness compared the to the ink presented in Table 6 which is suitable for printing the lower blocking layer  794 . The ink presented in Table 9 therefore can be readily removed from the ticket  700  when the play spot areas  716 A-H are removed to reveal the underlying play indicia  720 A-H.  
     [0318]FIG. 66 illustrates an alternative configuration of the upper blocking layer  830  which is a barred layer  834  that is printed with a material which is minimally conductive relative to the material used to print the circuit elements  732 A-H,  740 ,  750 A, and  750 B. The barred layer  834  includes laterally spaced-apart strips  836 A and  836 B which are substantially opaque and longitudinally span the play field portion  706 . The strips  836 A-B also cover the validation number  726  within the ticket identification portion  708  of the ticket  700 . The spaced-apart strips  836 A and  836 B define channels  838 A and  838 B for the resistive elements  738 A-H of the indicia circuit elements  732 A-H. The channels  838 A and  838 B contain the material used to print the upper blocking layer  830 . The space between the strip  836 A and the interface  804  between the play field portion  706  and the display portion  704  and the space between the strips  836 A and  836 B define channels  840 A and  840 B for the capacitive pick-up areas  734 A-H and  736 A-H of the indicia circuit elements  732 A-H. The layer that is exposed by the channels  840 A and  840 B is the seal coat layer  826  which, as previously stated, has a sheet resistivity greater than 10 8  Ω/□. The configuration of the barred layer  834  thus electrically isolates the capacitive pick-up areas  734 A-H and  736 A-H of the indicia circuit elements  732 A-H from the minimally conductive strips  836 A and  836 B. The barred layer  834  is the preferred form of the upper blocking layer  830  when the lower blocking layer  794  is printed as the barred layer  798  shown in FIG. 53. The upper blocking layer  830  is printed in registry with the lower blocking layer  794  so that the spaced-apart strips  836 A and  836 B of the upper barred layer  834  are aligned with the spaced-apart strips  800 A and  800 B of the lower barred layer  798 . Consequently, the channels  838 A and  838 B and the channels  840 A and  840 B which are defined by the upper barred layer  834  coincide with the channels  802 A and  802 B and the channels  806 A and  806 B, respectively, which are defined by the lower barred layer  798 . In FIG. 66, the play indicia  720 A and the associated release coat portion  828 A are shown in phantom for reference. The play indicia  720 A and the associated release coat portion  828 A are printed on the ticket  700  so that the play indicia  720 A and the associated release coat portion  828 A are aligned with both the strip  836 A of the upper blocking layer  830  and the strip  800 A of the lower blocking layer  794 . The play indicia  720 A and the associated release coat portion  828 A are thus within both the channel  838 A defined by the upper blocking layer  830  and the channel  802 A defined by the lower blocking layer  794 .  
     [0319]FIG. 67 illustrates another embodiment of the upper blocking layer  830  which includes a patterned layer  842  that is printed with a material that is minimally conductive relative to the circuit elements  732 A-H,  740 ,  750 A, and  750 B. The patterned layer  842 , which is substantially opaque, overlies the entire play field portion  706  of the ticket  700  and also covers the validation number  726  within the ticket identification portion  708  of the ticket  700 . The patterned layer  842  defines several apertures  844 -H which electrically isolate portions of the indicia circuit elements  732 A-H. Specifically, the apertures  844 -H are positioned and shaped to coincide with the first capacitive pick-up areas  734 A-H of the indicia circuit elements  732 A-H. The exposed layer within the apertures  844 A-H is the seal coat layer  826  which has a sheet resistivity greater than 10 8  Ω/□. The patterned layer  842  is the preferred form of the upper blocking layer  830  when the lower blocking layer  794  is printed in the patterned layer  808  shown in FIG. 54. The upper blocking layer  830  is printed in registry with the lower blocking layer  794  so that the apertures  844 A-H defined by the patterned layer  842  are aligned with the apertures  810 A-H defined by the lower patterned layer  808 . Thus, for example, the aperture  844 A of the upper blocking layer  830  coincides with the aperture  810 A of the lower blocking layer  794 . In FIG. 67, the play indicia  720 A and the associated release coat portion  828 A are shown in phantom for reference. The play indicia  720 A and the associated release coat layer portion  828 A are printed on the ticket adjacent the aperture  844 A in the upper blocking layer  830 . Because the upper blocking layer  830  is printed in registry with the lower blocking layer  794 , the play indicia  720 A and the associate release coat layer portion  828 A are also printed adjacent the aperture  810 A in the lower blocking layer  794 . A suitable ink for printing the upper blocking layer  830  either as the barred layer  834  or as the patterned layer  842  was given previously in Table 9.  
     [0320] The station  784  prints the next layer which consists of the indicia circuit elements  732 A-H. The appearance of the ticket  700  at this point varies according to the configuration of the upper blocking layer  830 . FIG. 68 illustrates the ticket  700  when the upper blocking layer  830  is printed as the continuous layer  832 . Since in the preferred embodiment the continuous layer  832  is printed with a material that does not interfere with the electrical signatures of the circuit elements  732 A-H,  740 ,  750 A, and  750 B there is no need to isolate any portions of the indicia circuit elements  732 A-H from the upper blocking layer  830 . Consequently, the indicia circuit elements  732 A-H are printed directly on the continuous layer  832 . The indicia circuit elements  732 A-H are positioned to align with the play indicia  720  so that the resistive elements  738  overlie the play indicia  720 . Thus, for example, the indicia circuit element  732 A is printed on the layer  832  to align with the play indicia  720 A and the associated release coat layer portion  828 A (shown in phantom) so that the resistive element  738 A overlies the play indicia  720 A and the associated release coat layer portion  828 A.  
     [0321]FIG. 69 illustrates the form of the ticket  700  when the upper blocking layer  830  is printed as the barred layer  834 . In FIG. 69 the play indicia  720 A and the associated release coat layer portion  828 A are shown in phantom for reference. However it should be kept in mind that neither the play indicia  720 A and nor the associated release coat layer portion  828  would be visible because of the upper blocking layer  830 . The indicia circuit elements  732 A-H are printed on the ticket  700  so that the first capacitive pick-up areas  734 A-H and the second capacitive pick-up areas  736 A-H are printed in registry with the channels  840 A and  840 B defined by the barred layer  834 . For example, the indicia circuit element  732 A is printed on the ticket  700  so that the first and second capacitive pick-up areas  734 A and  734 B are positioned within the channel  840 A. Similarly, the indicia circuit element  732 F is printed on the ticket  700  so that the first and second capacitive pick-up areas  734 F and  736 F are positioned within the channel  840 B. As noted earlier, the layer exposed in the channels  840 A and  840 B is the seal coat layer  826  which has a sheet resistivity greater than about 10 8  Ω/□. The channels  840 A and  840 B defined by the barred layer  834  thus electrically isolate the first capacitive pick-up areas  734 A-H and the second capacitive pick-up areas  736 A-H of the indicia circuit elements  732 A-H from the minimally conductive strips  838 A and  838 B. Moreover, the upper blocking layer  830  is printed in registry with the lower blocking layer  794  so that the upper channels  840 A and  840 B are aligned with the lower channels  802 A and  802 B. The first capacitive pick-up areas  734 A-H and the second capacitive pick-up areas  736 A-B of the indicia circuit elements  732 A-H therefore are electrically isolated from the minimally conductive strips  800 A and  800 B in the lower blocking layer  794 .  
     [0322] The indicia circuit elements  732 A-H are also printed on the ticket  700  so that the resistive elements  738 A-H are aligned with the strips  836 A-B and overlie the play indicia  720 A-H. For example, the indicia circuit element  732 A is printed on the ticket  700  so that the resistive element  738 A is printed on the strip  836 A, within the channel  838 A, and overlies the play indicia  720 A and the associated release coat layer portion  828 A (shown in phantom). Similarly, the indicia circuit element  732 G is printed on the ticket  700  so that the resistive element  738 G is printed on the strip  836 B, within the channel  838 B, and overlies the play indicia  720 G (not shown) and the associated release coat layer portion  828 G (not shown). In addition, the strips  826 A and  836 B of the upper barred blocking layer  834  are printed in registry with the strips  800 A and  800 B of the lower barred blocking layer  798 . Consequently, the play indicia  720 A-H are intermediate the strips  836 A-B and  800 A-B of the upper and lower barred blocking layers,  834  and  798  respectively, and so are protected against surreptitious detection by candling.  
     [0323]FIG. 70 illustrates the form of the ticket  700  when the upper blocking layer  830  is printed as the patterned layer  842 . The play indicia  720 A and the associated release coat layer portion  828 A are shown in phantom for reference. However it should be kept in mind that neither the play indicia  720 A and nor the associated release coat layer portion  828  would be visible because of the upper blocking layer  830 . The indicia circuit elements  732 A-H are printed on the ticket  700  so that the first capacitive pick-up areas  734 A-H are in registry with and positioned within the apertures  844 A-H defined by the upper patterned blocking layer  842 . For example, the first capacitive pick-up area  734 A of the indicia circuit element  732 A is in registry with and positioned within the aperture  844 A. Similarly, the first capacitive pick-up area  734 F of the indicia circuit element  732 A is in registry with and positioned within the aperture  844 F. As noted earlier, the layer exposed in the apertures  844 A-H is the seal coat layer  826  which has a sheet resistivity that is greater than about 10 8  Ω/□. The apertures  844 A-D defined by the upper patterned blocking layer  842  thus electrically isolate the first capacitive pick-up areas  734 A of the indicia circuit elements  732 A-H from the minimally conductive layer  842 . Moreover, the upper patterned blocking layer  842  is printed in registry with the lower patterned blocking layer  808  so that the upper apertures  844 A-H are aligned with the lower apertures  810 A-H. The first capacitive pick-up areas  734 A-H of the indicia circuit elements  732 A-H therefore are electrically isolated from the minimally conductive layer  808  as well. The indicia circuit elements  732 A-H are also printed on the ticket  700  so that the resistive elements  738 A-H overlie the play indicia  720 A-H. For example, the resistive element  738 A of the indicia circuit element  732 A overlies the play indicia  720 A. Similarly, the resistive element  738 F is printed on the ticket  700  to overlie the play indicia  720 F (not shown). Moreover, because the upper patterned blocking layer  842  is printed in registry with the lower patterned blocking layer  808 , the play indicia  720 A-H are protected against candling.  
     [0324] Printing press station  786  prints the next layer on the ticket which is a removable scratch-off coating  846 . As shown in FIG. 71, the scratch-off coating  846  is printed as a continuous layer that covers the play field portion  706  of the ticket  700  and the validation number  726  within the ticket identification portion  708  of the ticket. In order not to interfere with the electrical signatures of the circuit elements  732 A-H,  740 ,  750 A, and  750 B, the electrical conductivity of the scratch-off coating  846  should be significantly less that the electrical conductivity of the circuit elements  732 A-H,  740 ,  750 A, and  750 B. In the preferred embodiment, the sheet resistivity of the scratch-off coating  846  is greater than 10 8  Ω/□. A suitable formulation for the scratch-off coating  846  is given in Walton, U.S. Pat. No. 4,726,608. The remaining two printing press stations  788  and  790  apply overprint graphics such as the play spot areas  716 A-H, the play spot graphics  718 , the void-if-removed area  722 , and the overprint graphics  724  and thus provide the finished appearance of the ticket  700  as shown in FIG. 49.  
     [0325] The structure of the ticket  700  can be simplified by replacing the separate seal coat layer  826 , shown in FIG. 63, and the discontinuous release coat layer  828 , shown in FIG. 64, with a combined seal-release coat layer, generally denoted as  848 . Like the release coat  828 , the combined seal-release coat layer  848  is not continuous but instead consists of discreet layer portions  848 A-H that are associated with the play indicia  720 A-H and a discrete layer portion  848 I that is associated with the validation number  736 . For example, as shown in FIG. 72 the combined seal-release coat layer  848  is printed on the primer  820  so that the seal-release coat layer portion  848 A covers the play indicia  720 A. Similarly, the combined seal-release coat portion  848 G covers the play indicia  720 G. In addition, the seal-release coat portion  848 I covers the validation number  726 . The combined seal-release coat  848  protects the play indicia  720 A-H and the validation number  726  against abrasion. The combined seal-release coat  848  also ensures that the layers which overlie the play indicia  720 A-H and the validation number  726  can be removed to reveal the play indicia  720 A-H and the validation number  726 . In addition, as explained in reference to FIG. 75, the discrete seal-release coat portions  848 A-H help to ensure that the electrical signatures of the indicia circuit elements  732 A-H change when the layers overlying the play indicia  720 A-H are removed. In order not to interfere with the electrical signatures of the circuit elements  732 A-H,  740 ,  750 A, and  750 B, the electrical conductivity of the seal-release coat layer  848  should be significantly less than the electrical conductivity of the circuit elements  732 A-H,  740 ,  750 A, and  750 B. In the preferred embodiment, the sheet resistivity of the seal-release coat  848  is greater than about 10 8  Ω/□. However, since the seal-release coat layer  848  does not contact any of the capacitive pick-up areas  734 A-H.  736 A-H,  742 A-H,  744 A-H,  752 A-B, and  754 A-B, a lesser sheet resistivity, for example about 10 7  Ω/□, would be acceptable.  
     [0326] The printing sequence for the ticket changes slightly when the seal-release coat  848  is used instead of the separate seal coat layer  826  and the separate release coat layer  828 . Instead of printing the seal coat  826  on the primer layer  820 , station  778  prints the seal-release coat  848  on the primer layer. Station  780  then prints the upper blocking layer  830  as previously described with reference to FIGS.  65 - 67  and station  782  prints the indicia circuit elements  732 A-H as previously described with reference to FIGS.  68 - 70 . It should be noted that when the combined seal-release coat  848  is used the primer layer  820 , instead of the seal coat layer  826 , is exposed in the channels  840 A and  840 B defined by the upper barred blocking layer  834  and in the apertures  844 A-D defined by the upper patterned blocking layer  842 . However, like the seal coat layer  826  the primer layer  820  has a sheet resistivity that is greater than 10 8  Ω/□. The ticket  700  therefore functions in the same manner as described with reference to FIGS.  65 - 70  when the seal-release coat layer  848  is used instead of the separate seal coat  826  and the separate release coat  828 . This printing sequence also makes it possible to apply the indicia circuit elements  732 A-H twice, at stations  782  and  784 . As explained below with reference to FIGS.  75 - 76 , portions of the indicia circuit elements  732 A-H are removed when portions of the scratch-off layer  846  within the play spot areas  716 A-H are removed to reveal the play indicia  720 A-H. Consequently, the ink used to print the indicia circuit elements  732 A-H has a reduced graphic adhesiveness relative to the ink used to print the integrity circuit elements  740  and the data circuit elements  750 A-B. The reduced graphic adhesiveness of the ink used to print the indicia circuit elements  732 A-H, coupled with the high speed of the gravure printing press  760  can result in small holes, known as picking, in the indicia circuit elements  732 A-H. FIGS. 73 and 74 present an enlarged representation of one of the indicia circuit elements  732 A-H, for example, the element  732 A. In FIG. 73 a small portion  850  of the indicia circuit element  732 A has been picked-off during the printing of the element  732 A. Similarly, in FIG. 74 a different small portion  852  of the indicia circuit element  732 A has been picked-off during the printing of the element  732 A. The resulting discontinuity in the indicia circuit element  732 A in FIGS,  73  and  74  can lead to errors in detecting the electrical signature of the indicia circuit element  732 A. However, if the two illustrations of the indicia circuit element  732 A in FIGS. 73 and 74 are superimposed, for example, by laying the indicia circuit element  732 A in FIG. 74 over the indicia circuit element  732 A in FIG. 73 in registry therewith, the combined image does not suffer from any discontinuities. Therefore, by printing the indicia circuit elements  732 A-H at two of the stations, for example at the stations  782  and  784 , such that the two layers of the indicia circuit elements  732 A-H are in registry with each other, discontinuities in the printed indicia circuit elements  732 A-H can be reduced or eliminated.  
     [0327]FIG. 75 presents an enlarged view of one of the indicia circuit elements, for example circuit element  720 A, and the underlying associated play indicia  720 A. FIG. 75 also shows the position and configuration of the associated release coat layer portion  828 A or the associated seal-release coat layer portion  848 A. As previously explained, the release coat  828  or the seal-release coat  848  is interposed between the play indicia  732 A-H and the indicia circuit elements  732 A-H. Although not shown, it is to be understood that the upper blocking layer  830  is also interposed between the release coat  828  or the seal-release coat  848  and the indicia circuit elements  732 A-H. As shown in FIG. 75, in the preferred embodiment the resistive element  738 A is printed over either the release coat layer portion  828 A or the seal-release coat layer portion  848 A so that a portion  854  extends beyond the release coat layer portion  828 A or the seal-release coat layer portion  848 A thereby ensuring that the electrical signature of the circuit element  732  changes when the layers overlying the play indicia  720  are lifted or removed.  
     [0328]FIG. 76 shows an alternative embodiment of an indicia circuit element  856  according to the invention. Like the indicia circuit elements  732 A-H, the indicia circuit element  856  includes the first capacitive pick-up area  734 , the second capacitive pick-up area  736 , and the resistive element  738 . The main difference between the indicia circuit element  856  and the indicia circuit elements  732 A-H is that the second capacitive pick-up area  736  is no longer aligned with the first capacitive pick-up area  734  but instead is aligned with the resistive element  738 . This change is of primary importance when the upper blocking layer  830  is printed as the barred layer  834  in which case the second capacitive pick-up area  736  of the indicia circuit element  856  is printed on the ticket  700  so that the second capacitive pick-up area  736  either is printed on the strip  836 A, within the channel  838 A, and or is printed on the strip  836 B, within the channel  838 B. In all other respects, the indicia circuit element  856  operates in the same manner as the indicia circuit elements  732 A-H.  
     [0329] The complete structure of the ticket  700  offers several security advantages. The lower and upper blocking layers  794  and  830  help to protect against surreptitious detection of the play indicia  720 A-H and the circuit elements  732 A-H,  740 ,  750 A, and  750 B by candling or fluorescence. The integrity circuit  740  provides a way of determining if an attempt has been made to alter the bar code  730 , for example, by cutting and replacing the bar code  730 . The data circuits  750 A and  750 B offer at least partial ticket authenticity and integrity information in binary form. The indicia circuit elements  732 A-H both protect the play indicia  720 A-H against fraudulent manipulation and provide a way to verify the gaming value of the ticket  700 . As noted previously with reference to FIGS. 75 and 76, in the preferred embodiment the indicia circuit elements  732 A-H are printed over either the release coat portions  828 A-H or the seal-release coat portions  848 A-H so that portions  854 A-H of the resistive elements  738 A-H extend beyond the release coat layer portions  828 A-H or the seal-release coat layer portions  848 A-H. When one of the play spot areas  716 A-H, for example the play spot area  716 A, is lifted to reveal the underlying play indicia  720 A, the resistive element  738 A will be fractured because the portion  854 A of the resistive element  738 A remains affixed to the ticket  700 . Consequently, if an attempt is made thereafter to replace the play spot area  716 A and the fractured resistive element  738 A, the resulting change in the electrical signature of the indicia circuit element  732 A is detected by the sensor array  502  of the electronic verification machine  500 . In addition, when a play spot area such as the play spot area  716 A is legitimately removed to reveal the play indicia  720 A, the electrical continuity between the capacitive pick-up area  734 A and  736 A of the indicia circuit element  732 A is broken when the resistive element  738 A is removed with the play spot area  716 A. The resulting change in the electrical signature of the indicia circuit element  738 A can then be detected by the sensor array  502  of the electronic verification machine  500 , thereby providing a way to determine the gaming value of the ticket  700 .  
     [0330] IX. A Marker Ticket In Accordance With The Invention.  
     [0331] FIGS.  77 - 83  show a marker ticket  860  which can be used with the electronic verification machine  500  (shown in FIGS.  38 - 40 ). The marker card  860  is the type used to record a user&#39;s choices relative to pre-set options. For example, marker cards, such as the marker card  860 , can be used in playing games such as Bingo or Keno. Marker cards like the card  860  are also used to record a user&#39;s choice of numbers or other indicia in on-line lottery games. The marker card  860 , like the probability game ticket  700 , can be used in conjunction with the electronic verification machine  500  of the type shown in FIGS.  38 - 40 . FIG. 77 presents the finished appearance of the card  860  which is printed on a substrate, such as paper or card stock, and includes various printed information such as the identity or title  864  of the card  860 , inventory data  866 , and a machine-readable bar code  868 . A boarder  869  delineates the play area of the card  860  and is printed as overprint graphics. The card  860  also includes an indicia-array area  870  that has a group of indicia spot areas  872 A-L, each of which includes an overlay indicia  874 A-L. The indicia spot areas  872 A-L and the overlay indicia  874 A-L are printed as overprint graphics. Each of the indicia spot areas  872 A-L covers a play indicia  876 A-L (shown in FIGS.  79 - 81 ) that is identical to the corresponding overlay indicia  874 A-L. For example, the overlay indicia  874 E in indicia spot area  872 E is a diamond and the play indicia  876 E (shown in FIGS.  79 - 81 ), which is located beneath the indicia spot area  872 E is also a diamond. The indicia spot area  872 A has been removed to reveal the underlying associated play indicia  876 A. The overlay indicia  874 A-L and the play indicia  857 A-L define longitudinal data channels  877 A-C. For example, the overlay indicia  874 A-D and the associated play indicia  876 A-D are in the data channel  877 A and the overlay indicia  874 I-L and the associated play indicia  876 I-L are in data channel  877 C. The overlay indicia  874 A-L and the play indicia  876 A-L are used to represent the pre-set options among which a user can choose.  
     [0332] The card  860  also includes circuit elements, generally denoted as  878 , which when coupled to the sensor array  502  of the electronic verification machine  500  serve to verify or record the user&#39;s chosen options. As shown in FIG. 78 the card  860  has three circuit elements  878 A-C, each of which includes a resistive element, generally denoted as  880 , and an upper and a lower terminal capacitive pick-up area, generally denoted as  882  and  884 , which are connected to and extend from the opposites ends  888  and  890  of the resistive element  880 . For example, the circuit element  878 A includes the resistive element  880 A and the two terminal capacitive pick-up areas  882 A and  884 A which are aligned with each other and are connected to and laterally extend from the first end  888 A and the second end  890 A, respectively, of the resistive element  880 A. Each of the circuit element  878  also includes intermediate capacitive pick-up areas, generally denoted as  892 , that are aligned with the terminal capacitive pick-up areas  888  and  890  and are connected to the resistive elements  880  intermediate the terminal capacitive pick-up areas  888  and  890 . For example, the circuit element  878 A has three intermediate capacitive pick-up areas  892 A,  892 A′, and  892 A″, that are aligned with the terminal capacitive pick-up areas  888 A and  890 A and are connected to the resistive element  880 A intermediate the terminal capacitive pick-up areas  888 A and  890 A. Similarly, the circuit element  878 B has three intermediate capacitive pick-up areas  892 B,  892 B′, and  892 B″, that are aligned with the terminal capacitive pick-up areas  888 B and  890 B and are connected to the resistive element  880 B intermediate the terminal capacitive pick-up areas  888 B and  890 B. The circuit elements  878 A-C are positioned on the card  860  so that the resistive elements  880 A-C are aligned with and positioned in the data tracks  877 A-C defined by the overlay indicia  874 A-L and the play indicia  876 A-L and so that portions  894 A-L of the resistive elements  880 A-L are aligned with the overlay indicia  874 A-L and with the play indicia  876 A-L. For example, the portion  894 A-D of the resistive element  880 A are aligned with the overlay indicia  874 A-D and with the associated play indicia  876 A-D. Similarly, the portions  8941 -L of the resistive element  880 C are aligned with the overlay indicia  874 I-L and with the associated play indicia  876 I-L.  
     [0333] Several layers are needed to provide the finished card  860  shown in FIG. 77. As shown in FIG. 79, the first layer  896  is printed directly on the substrate  862  and includes the play indicia  876 A-L. The first layer  896  can also include the title  864 , the inventory data  866 , and the bar code  868 . The play indicia  876 A-L are printed on the card substrate  862  with the indicia-array portion  870  and are positioned to define the data channels  877 A-C. For example, the play indicia  876 E-H define the data channel  877 B. In the preferred embodiment, the play indicia  876 A-L are printed in a different color than the overlay indicia  874 A-L in order to make it easier for a user of the card  860  to determine which if the overlay indicia  874 A-L have been removed. The next layer is a seal coat layer  898  that protects the play indicia  876 A-L against abrasion. As shown in FIG. 80, in the preferred embodiment the seal coat layer  898  is printed within the indicia-array portion  870  of the card  860  as a continuous layer that overlies the play indicia  876 A-L. In order not to interfere with the electrical signatures of the circuit elements  878 A-C the electrical conductivity of the seal coat layer  898  should be significantly less that the electrical conductivity of the circuit elements  878 A-C. In the preferred embodiment, the sheet resistivity of the seal coat layer  898  is greater than 10 8  Ω/□. A suitable formulation for the seal coat layer  898  is given in Walton, U.S. Pat. No. 4,726,608.  
     [0334] Next, a release coat  900  is printed on the card  860  so that the release coat  900  overlies the play indicia  876 A-L but preferably is not located below any of the capacitive pick-up areas  882 ,  884 , and  892  of the circuit elements  878 A-C. For example, as shown in FIG. 81 the release coat  900  can be printed as a barred layer  902  that includes longitudinally spaced-apart strips  904 A-D which are printed within and laterally span the indicia-array portion  870  of the card  860 . Each of the strips  904 A-D covers a row of play indicia  876 A-L. For example, the strip  904 A laterally spans the indicia-array portion  870  of the card  860  and covers the play indicia  876 A,  876 E, and  876 I. Similarly, the strip  904 B covers the play indicia  876 B,  876 F, and  876 J, the strip  904 C covers the play indicia  976 C,  876 G, and  876 K, and the strip  904 D covers the play indicia  876 D,  876 H, and  876 L. The material exposed between two adjacent strips  904 A-D, for example the strip  904 A and the strip  904 B, is the seal coat layer  898  and the material exposed adjacent the strips  904 A-D but outside of the indicia-array portion  870  of the card  860  is the substrate  862 . Alternatively, as shown in FIG. 82, the release coat layer  900  can be printed as a discontinuous layer  906  that includes discreet release coat spots  908 A-L each of which covers an associated play indicia  876 A-L. For example, the release coat spot  908 A covers the play indicia  876 A and the release coat spot  908 G covers the play indicia  876 G. Within the indicia-array portion  870  of the card  860  the material exposed between adjacent release coat spots  908 A-L, for example the release coat spot  908 B and the release coat spot  908 F, is the seal coat layer  898 . Outside of the indicia-array portion  870  of the card  860  the material exposed adjacent the release coat spots  908 A-L is the substrate  862 . In order not to interfere with the electrical signatures of the circuit elements  878 A-C the electrical conductivity of the release coat layer  900  should be significantly less that the electrical conductivity of the circuit elements  878 A-C. In the preferred embodiment, the sheet resistivity of the release coat layer  900  is greater than 10 8  Ω/□. However, since the release coat layer  900  does not underlie any of the capacitive pick-up areas  882 ,  884 , and  892 , a lesser sheet resistivity, for example about 10 7  Ω/□, would be acceptable. A suitable formulation for the release coat layer  900  is given in Walton, U.S. Pat. No. 4,726,608.  
     [0335] Alternatively, a combined seal-release coat  910  can be used instead of the separate seal coat and release coat layers  898  and  900  shown in FIGS.  80 - 82 , in which case, the combined seal-release coat  910  is printed on the card  860  so that the seal-release coat  910  overlies the play indicia  876 A-L but is not located below any of the capacitive pick-up areas  882 ,  884 , and  892  of the circuit elements  878 A-C. For example, as shown in FIG. 83 the seal-release coat  910  can be printed as a barred layer  912  that includes longitudinally spaced-apart strips  914 A-D which are printed within and laterally span the indicia-array portion  870  of the card  860 . Each of the strips  914 A-D covers a row of play indicia  876 A-L. For example, the strip  914 A laterally spans the indicia-array portion  870  of the card  860  and covers the play indicia  876 A,  876 E, and  876 I. Similarly, the strip  914 B covers the play indicia  876 B,  876 F, and  876 J, the strip  914 C covers the play indicia  976 C,  876 G, and  876 K, and the strip  914 D covers the play indicia  876 D,  876 H, and  876 L. The exposed material around any of the strips  914 A-D is the substrate  862 . Alternatively, as shown in FIG. 84, the seal-release coat layer  910  can be printed as a discontinuous layer  916  that includes discreet seal-release coat spots  918 A-L each of which covers an associated play indicia  876 A-L. For example, the seal-release coat spot  918 A covers the play indicia  876 A and the seal-release coat spot  918 G covers the play indicia  876 G. The exposed material around any of the seal-release coat spots  918 A-L is the substrate  862 . In order not to interfere with the electrical signatures of the circuit elements  878 A-C the electrical conductivity of the seal-release coat layer  910  should be significantly less that the electrical conductivity of the circuit elements  878 A-C. In the preferred embodiment, the sheet resistivity of the seal-release coat layer  910  is greater than 10 8  Ω/□. However, since the seal-release coat layer  910  does not underlie any of the capacitive pick-up areas  882 ,  884 , and  892 , a lesser sheet resistivity, for example about 10 7  Ω/□, would be acceptable.  
     [0336] The circuit elements  878 A-C are printed on the card  860  immediately after either the release coat  900  or the seal-release coat  910 . Since the portions  894 A-L of the resistive elements  880 A-C are removed when the indicia spot areas  872 A-L and associated portions of the scratch-off layer  920  are removed to revel the play indicia  876 A-L, the ink used to print the circuit elements  878 A-C should have a relatively reduced adhesiveness. In addition, the ink used to print the circuit elements should have a relatively high conductivity. In the preferred embodiment, the ink used to print the circuit elements  878 A-C has a sheet resistivity of about 1 KΩ/□. A suitable formulation for the ink used to print the circuit elements  878 A-L was given previously in Table 5.  
     [0337]FIG. 85 illustrates the configuration of the card  860  when the circuit elements  878 A-C are printed over the barred release coat layer  902 . As noted earlier with reference to FIG. 78, the circuit elements  878 A-C are positioned on the card  860  so that the resistive elements  880 A-C are aligned with and positioned in the data tracks  877 A-C. Each resistive element  880 A therefore overlies a column of the play indicia  876 A-L and the portions  894 A-L of each resistive element  880 A-D directly overlie one of the play indicia  876 A-L. For example, the circuit element  878 A overlies the play indicia  876 A-D and the portions  894 A-D of the resistive element  880 A directly overlie the play indicia  876 A-D. Similarly, the circuit element  878 B overlies the play indicia  876 E-H and the portions  894 E-H of the resistive element  880 B directly overlie the play indicia  876 E-H. In addition, the circuit element  878 C overlies the play indicia  876 I-L and the portions  894 I-L of the resistive element  880 C directly overlie the play indicia  876 I-L. Thus, although the play indicia  876 A and  876 G are shown for reference, it should be kept in mind that the play indicia  876 A and  876 G would not actually be visible because of the overlying portions  894 A and  894 G of the resistive elements  880 A and  880 B, respectively. Similarly, the play indicia  876 I and  876 J, although shown for reference, would not actually be visible because of the overlying portions  894 I and  894 J of the resistive element  880 C. As previously noted with reference to FIG. 81, each of the longitudinally spaced-apart strips  904 A-D of the barred release coat  902  covers a row of play indicia  876 A-L so that within the play indicia array portion  870  the exposed material between adjacent strips  904 A-D is the seal coat layer  898 . Moreover, outside of the indicia array portion  870  the exposed material adjacent the strips  904 A-D is the substrate  862 . Consequently, the terminal capacitive pick-up areas  882 A-C and  884 A-C are printed directly on the substrate  862 , as are the intermediate capacitive pick-up areas  89 A,  892 A′, and  892 A″ of the circuit element  878 A. The intermediate capacitive pick-up areas  892 B,  892 B′, and  892 B″ of the circuit element  878 B and the intermediate capacitive pick-up areas  892 C,  892 C′, and  892 C″ of the circuit element  878 C are printed on the seal coat layer  898 . FIG. 86 illustrates the configuration of the card  860  when the circuit elements  878 A-C are printed over the discontinuous release coat layer  906 . The circuit elements  878 A-C are positioned on the card  860  so that the resistive elements  880 A-C are aligned with and positioned in the data tracks  877 A-C. Each resistive element  880 A therefore overlies a column of the play indicia  876 A-L and the portions  894 A-L of each resistive element  880 A-D directly overlie one of the play indicia  876 A-L. Consequently, although shown for reference the play indicia  876 A,  876 G,  876 I, and  876 J would not be visible because of the overlying portions  894 A,  894 I,  894 I, and  894 J of the resistive elements  880 A-C. As noted previously with reference to FIG. 82, within the indicia-array portion  870  of the card  860  the material exposed between adjacent release coat spots  908 A-L, for example the release coat spot  908 B and the release coat spot  908 F, is the seal coat layer  898 . In addition, outside of the indicia-array portion  870  of the card  860  the material exposed adjacent the release coat spots  908 A-L is the substrate  862 . Consequently, the terminal capacitive pick-up areas  882 A-C and  884 A-C are printed directly on the substrate  862 , as are the intermediate capacitive pick-up areas  89 A,  892 A′, and  892 A″ of the circuit element  878 A. The intermediate capacitive pick-up areas  892 B,  892 B′, and  892 B″ of the circuit element  878 B and the intermediate capacitive pick-up areas  892 C,  892 C′, and  892 C″ of the circuit element  878 C are printed on the seal coat layer  898 .  
     [0338]FIG. 87 illustrates the configuration of the card  860  when the circuit element  878 A-C are printed on the barred seal-release coat  912 . The circuit elements  878 A-C are positioned on the card  860  so that the resistive elements  880 A-C are aligned with and positioned in the data tracks  877 A-C. Each resistive element  880 A therefore overlies a column of the play indicia  876 A-L and the portions  894 A-L of each resistive element  880 A-D directly overlie one of the play indicia  876 A-L. Consequently, although shown for reference the play indicia  876 A,  876 G,  876 I, and  876 J would not be visible because of the overlying portions  894 A,  894 G,  894 I, and  894 J of the resistive elements  880 A-C. As noted earlier with reference to FIG. 83, the exposed material around any of the strips  914 A-D is the substrate  862 . Consequently, all of the terminal capacitive pick-up areas  882 A-C and  884 A-C and all of the intermediate capacitive pick-up areas  892 A,  892 A′,  892 A″,  892 B,  892 B′,  892 B″,  892 C,  892 C′, and  892 C″ are printed directly on the substrate  862 .  
     [0339]FIG. 88 illustrates the configuration of the card  860  when the circuit elements  878 A-C are printed over the discontinuous seal-release coat layer  916 . The circuit elements  878 A-C are positioned on the card  860  so that the resistive elements  880 A-C are aligned with and positioned in the data tracks  877 A-C. Each resistive element  880 A therefore overlies a column of the play indicia  876 A-L and the portions  894 A-L of each resistive element  880 A-D directly overlie one of the play indicia  876 A-L. Consequently, although shown for reference the play indicia  876 A,  876 G,  876 I, and  876 J would not be visible because of the overlying portions  894 A,  894 G,  894 I, and  894 J of the resistive elements  880 A-C. As previously noted with reference to FIG. 84, the exposed material around any of the seal-release coat spots  918 A-L is the substrate  862 . Consequently, all of the terminal capacitive pick-up areas  882 A-C and  884 A-C and all of the intermediate capacitive pick-up areas  892 A,  892 A′,  892 A″,  892 B,  892 B′,  892 B″,  892 C,  892 C′, and  892 C″ are printed directly on the substrate  862 .  
     [0340] A scratch-off coating  920  is then printed on the card  860  so that the scratch-off coating  920  span the entire indicia array portion  870  of the card  860  and covers all of the circuit elements  878 A-C, as shown in FIG. 89. In order not to interfere with the electrical signatures of the circuit elements  878 A-C the electrical conductivity of the scratch-off coating  920  should be significantly less that the electrical conductivity of the circuit elements  878 A-C. In the preferred embodiment, the sheet resistivity of the scratch-off coating  920  is greater than 10 8  Ω/□. A suitable formulation for the scratch-off coating  920  is given in Walton, U.S. Pat. No. 4,726,608. The boarder  869 , the indicia spots areas  872 A-L and the overlay indicia  874 A-L are then printed as overprint graphics to give the card  860  the finished appearance shown in FIG. 77.  
     [0341] The operation of the circuit elements  878 A-C is best explained with reference to FIGS. 77, 79, and  85 - 88 . Each of the capacitive pick-up areas  882 A-C,  884 A-C,  892 A,  892 A′,  892 A″,  892 B,  892 B′,  892 B″,  892 C,  892 C′, and  892 C″ is sized, shaped, and positioned on the card  860  so that each of the capacitive pick-up areas  882 A-C,  884 A-C,  892 A,  892 A′,  892 A″,  892 B,  892 B′,  892 B″,  892 C,  892 C′, and  892 C″ can capacitively couple with either the excitation plate  576  or one of the sensor plates  574  of the sensor array  502  in the electronic verification machine  500 . Consequently, all of the intermediate capacitive pick-up areas  892 A,  892 A′,  892 A″,  892 B,  892 B′,  892 B″,  892 C,  892 C′, and  892 C″ function as both excitation and sensor capacitive pick-up areas when the card  860  is coupled to the electronic verification machine  500 . The terminal capacitive pick-up areas  882 A-C and  884 A-C, however, function only as either an excitation capacitive pick-up area or a sensor capacitive pick-up area depending on the direction in which the card  860  moves through the electronic verification machine  500 . For example, if the card moves through the electronic verification machine  500  so that the terminal capacitive pick-up areas  882 A-C first couple with the sensor array  502 , then the terminal capacitive pick-up areas  882 A-C function only as excitation capacitive pick-up areas and the terminal capacitive pick-up areas  884 A-C function only as sensor capacitive pick-up areas. Alternatively, if the card moves through the electronic verification machine  500  so that the terminal capacitive pick-up areas  884 A-C first couple with the sensor array  502 , then the terminal capacitive pick-up areas  884 A-C function only as excitation capacitive pick-up areas and the terminal capacitive pick-up areas  882 A-C function only as sensor capacitive pick-up areas. For ease of explanation, in the following discussion it is to be understood that the card  860  moves through the electronic verification machine  500  so that the terminal capacitive pick-up areas  882 A-C first couple with the sensor array  502  and so function only as excitation capacitive pick-up areas. Referring now to FIGS.  85 - 88 , when the card  860  first couples with the sensor array  502 , the terminal capacitive pick-up area  882 C serves as an excitation capacitive pick-up area and the intermediate capacitive pick-up area  892 C serves as a sensor capacitive pick-up area. In addition, the terminal capacitive pick-up area  892 C is joined to the intermediate capacitive pick-up area  892 C by the portion  894 I of the resistive element  880 C. The capacitive pick-up areas  882 C and  892 C and the associated portion  894 I of the resistive element  880 C therefore form a U-shaped circuit element. As the card  860  continues to move through the electronic verification machine  500 , the intermediate capacitive pick-up area  892 C and the intermediate capacitive pick-up area  892 C′ function as excitation and sensor capacitive pick-up areas, respectively, that are joined by the portion  894 J of the circuit element  880 C. Similarly, the intermediate capacitive pick-up area  892 C′ and the intermediate capacitive pick-up area  892 C″, together with the portion  894 K of the resistive element  880 C form a U-shaped circuit element, and the intermediate capacitive pick-up area  892 C″ and the terminal capacitive pick-up area  884 C, together with the portion  894 L of the resistive element  880 C form a U-shaped circuit element. Each of the circuit elements  878  therefore serves as a linear array of U-shaped circuit elements that are defined by two adjacent capacitive pick-up areas,  882 A-C and  892 A-C,  892 A-C and  892 A′-C′,  892 A′-C′ and  892 A″-C″,  892 A″-C″, and  884 A-C, and the associated portions  894 A-L of the resistive elements  880 A-C. Thus, when a given indicia spot area  872 A-L is removed to mark the card  860  and reveal the underlying play indicia  876 A-L, only the U-shaped circuit element which is partially defined by the associated portion  894 A-L of the resistive element  880 A-C is affected. For example, when the indicia spot area  872 A is removed to reveal the underlying play indicia  876 A as shown in FIG. 77, the only affected U-shaped circuit element is the one that is defined by the terminal capacitive pick-up area  882 A, the intermediate capacitive pick-up area  892 A and the associated portion  894 A of the resistive element  880 A.  
     [0342] It should be kept in mind that a similar result can be achieved if the card is printed with a plurality of separate U-shaped circuit elements, such as the data circuit elements  750 A-B of the ticket  700 . However, the method of printing the circuit elements  878  has advantages over printing individual U-shaped elements such as  750 A-B in that much fewer capacitive pick-up areas are required for each data bit. Also, for those applications where the play indicia  876 A-L are not required, the seal coat  898  can be omitted from the marker card  860 .  
     [0343] X. A Data Card According To The Invention.  
     [0344]FIG. 90 shows a data card  922  which can be used with the electronic verification machine  500 , shown in FIGS.  38 - 40 . The data card  922  includes circuit elements, generally denoted as  924 , that are printed directly on a substrate  926 . Each of the circuit elements  924  includes two terminal capacitive pick-up areas, generally denoted as  928  and  930 , and a data track, generally denoted as  932 , that spans between the two terminal capacitive pick-up areas  928  and  930 . In addition, each of the circuit elements  924  can include intermediate capacitive pick-up areas, generally denoted as  934 ,  936 , and  938 , that are positioned on the card  922  intermediate the terminal capacitive pick-up areas  928  and  930  and are aligned with the terminal capacitive pick-up areas  928  and  930 . As with the marker card  860 , each pair of adjacent capacitive pick-up areas, for example, the capacitive pick-up area  928 B and the capacitive pick-up area  934 B, or the capacitive pick-up area  934 B and the capacitive pick-up area  936 B, define partial U-Shaped circuit elements the remainder of which are defined by an associated portion  940 A-L of the data tracks  932 . The U-shaped circuit elements can in turn encode either a bit-off or “0” signal or a bit-on or “1” signal, depending on whether or not the associated portions  940 A-L of the data tracks  932  contain conductive material. For example, the U-shaped circuit element that is defined by the capacitive pick-up areas  928 A and  934 A and the associated portion  940 A of the data track  932 A encode a bit-off or “0” signal and the U-shaped circuit element that is defined by the capacitive pick-up areas  928 B and  934 B and the associated portion  940 E of the data track  932 B encodes a bit-on or “1” signal. Thus, reading from left to right, the first row of U-Shaped circuit elements encodes “011”, the second row of U-Shaped circuit elements encodes “110”, the third row of U-shaped circuit elements encodes “100” and the fourth row of U-shaped circuit elements encodes “111”. A suitable ink for printing the circuit elements  924 A-C for the data card  922  can be printed with the ink that was previously described in Table 1.  
     [0345]FIG. 91 illustrates an alternative embodiment of a data card  942  according to the invention. Like the data card  922 , the data card  942  includes circuit elements  924 A-C. The main difference between the data card  922  and the data card  942  is that the data card  942  includes a release coat  944  that is printed on the substrate  926  so that the release coat underlies the portions  940 A-L of the data tracks  932 A-C but does not underlie any of the capacitive pick-up areas  928 A-C,  930 A-C,  934 A-C,  936 A-C, and  938 A-C. As with the marker card  860 , the release coat  944  can be printed on the substrate  926  either as discreet release coat layer portions  946 A-F or as spaced-apart strips  948 A-B. The circuit elements  924 A-C are therefore printed on the data card  942  so that initially each of the data tracks  932 A-C contains conductive material in all of the portions  940 A-L of the data tracks  932 A-C. After the data card  942  is printed, specific portions  940 A-L of the data tracks  932 A-C are scratched-off to encode the desired binary data. For example the portion  940 A of the resistive track  932 A, the portion  940 G of the data track  932 B, and the portions  940 J and  940 K of the data track  932 C have been removed subsequent to printing the data card  942 . Thus, reading from left to right, the first row of U-Shaped circuit elements encodes “011”, the second row of U-Shaped circuit elements encodes “110”, the third row of U-shaped circuit elements encodes “100” and the fourth row of U-shaped circuit elements encodes “111”. A suitable ink for printing the circuit elements  924 A-C for the data card  942  was previously given in Table 1.  
     [0346] XI. A Laminated Document According To The Invention.  
     [0347]FIG. 92. shows a laminated document  950  that can be used with the electronic verification machine (shown in FIGS.  38 - 40 ). Laminated documents, such as the document  950 , have a variety of uses including protecting an information document against excessive wear. One example of a laminated document, such as the document  950 , is an identification card such as a driver&#39;s license where the information document is a photograph. Laminated documents, such as identification cards, can be altered, for example, by splitting the laminated document to remove the original identification document and then substituting a fraudulent identification document. The laminated document  905  helps to prevent such fraudulent misuse. As shown in FIG. 92, the document  950  includes a first laminate  952 , a second laminate  954 , and an information document  956 , such as a photograph. The laminated document  950  also includes two circuit elements  958  and  960 , each of which is secured to or printed on one of the laminates  952  and  954 . FIG. 93 illustrates the first laminate  952  which includes an upper surface  962  on which the circuit element  958  is printed. The laminate  952  preferably is made from a durable non-conductive material, such as plastic, that can be opaque and that has a sheet resistivity greater than 10 8  Ω/□. The outline of the information document  956  is shown in phantom for reference. The circuit element  958  includes two capacitive pick-up areas  964  and  966 . The capacitive pick-up area  966  is shaped and positioned on the upper surface  962  of the laminate  952  so that the capacitive pick-up area  966  capacitively couples with the excitation plate  576  of the sensor array  502  in the electronic verification machine  500 . The capacitive pick-up area  964  is shaped and positioned on the upper surface  962  of the laminate  952  so that the capacitive pick-up area  964  capacitively couples with one of the sensor plates  574  of the sensor array  502 . The circuit element  952  further includes a resistive element  968  that is connected to and extends between the capacitive pick-up areas  964  and  966  so that at least a portion  970  of the resistive element  968  underlies the information document  956  in the laminated document  950 .  
     [0348]FIG. 94 illustrates the second laminate  954  which includes a lower surface  972  on which the circuit element  960  is printed. The laminate  954  preferably is made from a transparent material, such as plastic, that has a sheet resistivity greater than 10  8  Ω/□. The outline of the information document  956  is shown in phantom for reference. The circuit element  960  includes two capacitive pick-up areas  974  and  976 . The capacitive pick-up area  976  is shaped and positioned on the lower surface  972  of the laminate  954  so that the capacitive pick-up area  976  capacitively couples with the excitation plate  576  of the sensor array  502  in the electronic verification machine  500 . The capacitive pick-up area  974  is shaped and positioned on the lower surface  972  of the laminate  954  so that the capacitive pick-up area  974  capacitively couples with one of the sensor plates  574  of the sensor array  502 . The circuit element  954  further includes a resistive element  978  that is connected to and extends between the capacitive pick-up areas  974  and  976  so that at least a portion  980  of the resistive element  978  overlays the information document  956  in the laminated document  950 . A suitable ink for printing the circuit elements  968  and  069  was presently previously in Table 1.  
     [0349] In making the finished laminated document  950  shown in FIG. 92, the information document  956 , shown in FIG. 95, is positioned on the first laminate  952  so that the portion  970  of the resistive element  960  underlies the information document  950 . The second laminate  954  is then inverted, relative to its configuration in FIG. 94, so that the lower surface  972  of the second laminate  954  is adjacent the upper surface  962  of the first laminate  952 . The second laminate  954  is also aligned with the information document  956  so that the portion  980  of the circuit element  960  overlies the information document  956 . The two laminates  952  and  954  are then bonded together to form the laminated document  950 . Thereafter, if an attempt is made to split the laminated document  950  and remove the information document  956 , one or both of the resistive elements  968  and  978  will be damaged or broken. The resulting change in the electrical signature of the affected circuit element  958  or  960  can then be detected by the sensor array  502  of the electronic verification machine  500 .  
     [0350] XII. A Third Electronic Verification Machine  
     [0351] A. Components  
     [0352] A third and preferred embodiment of an electronic verification machine  1000  according to the invention is shown in FIG. 96. The electronic verification machine  1000  includes a frame structure  1002  (shown in FIG. 97) which is enclosed within a housing  1004  that includes a cover section  1006 , a bottom section  1008 , and a front section  1010 . Although the exact configuration of the exterior of the electronic verification machine  1000  can vary, the exterior of the electronic verification machine  1000  preferably includes a display panel  1012 , a user interface  1014 , and a document interface  1016 , all of which are positioned along the cover section  1006 . The display panel  1012  can display instructions, such as “Insert Ticket” and can also display the results of document validation and verification testing. The display panel  1012  preferably consists of a commercially available display unit, such as a liquid crystal display, a gas discharge display, or a light emitting diode (LED) display. The user interface  1014  includes a numeric keypad, shown generally as  1018 , and function keys, shown generally as  1020 . The operator can use the user interface  1014  to manually enter data from the document into the electronic verification machine  1000 . The document interface  1016  includes a slot  1022  into which the document to be tested is inserted. In the preferred embodiment, the document interface  1016  also includes an exit slot  1024  from which the document being tested exits the electronic verification machine  1000 . In addition, the electronic verification machine  1000  preferably includes a door  1026  located on the front section  1010  of the housing  1004 . The door  1026  provides access to the document pathway and can be used to clear the pathway should the document become jammed within the electronic verification machine  1000 . The door  1026  also provides access to a mirror  1028  (shown in phantom) that is positioned along the inner surface of the door  1026 . As explained below, the mirror  1028  can be used to read certain kinds of data printed on the document. The door  1026  and associated front section  1010  also include a door position sensor  1029 . Indicator lights  1030  located on the front section  1010  can be used to indicate that the door  1026  is open or jammed, that a document is jammed within the document channel  1038 , or that the electronic verification machine  1000  is unable to scan a document.  
     [0353]FIG. 97 shows the electronic verification machine  1000  with the housing  1004  removed. The frame structure  1002  includes a base portion  1032  and a front portion  1034  that is generally aligned with the front section  1010  of the housing  1004  (as shown in FIG. 96). A sensor head  1036  is secured to the frame structure  1002  to form a channel  1038  intermediate the front portion  1034  of the frame structure  1002  and the sensor head  1036 . The channel  1038  defines the document pathway through the electronic verification machine  1000 . In the preferred embodiment of the invention, the sensor head  1036  is tensionably secured to the frame structure  1002  so that the document being tested is in intimate physical contact with a sensor array  1044  (shown in FIGS. 99 and 100) positioned on the sensor head  1036 . The sensor head  1036  therefore includes hinge pins  1040  that are rotatably mounted in hinge arms  1042  formed on the front portion  1034  of the frame structure  1002 . A tensioning guide  1046  is located along the sensor head  1036 , opposite the front portion  1034  of the frame structure  1002  and is secured to the frame structure  1002  by tensioning fasteners  1048 . The tensioning guide  1046  is preferably formed from a rigid material, such as metal, and the tensioning fasteners  1048  can be formed from any appropriate stretchable devices, such as springs. The tensioning guide  1046  helps to ensure that the document being tested maintains intimate physical contact with the sensor array  1044  while the hinge pins  1040  permit the sensor head  1036  to pivot slightly so that the electronic verification machine  1000  can accept documents of varying thickness. A ribbon connector  1050  extends through an aperture  1052  (shown in FIG. 98) formed in the tensioning guide  1046  and operatively connects the sensor head  1036  to a master control processing board  1054  which is affixed to the frame structure  1002 .  
     [0354] The electronic verification machine  1000  also includes a pressure roller  1056  which moves the document being tested through the document channel  1038  and through the exit slot  1024  (shown in FIG. 96). The pressure roller  1056  is supported in the frame structure  1002  via a shaft  1055  which also supports a pulley  1057 . A stepper motor  1058  is also supported on the frame structure  1002  via a shaft  1059 , on which is also mounted a pulley  1060 . A toothed belt  1061  looped around the pressure roller pulley  1057  and the stepper motor pulley  1060  connects the pressure roller  1056  to the stepper motor  1058 . As explained in more detail below, the stepper motor  1058  is operatively connected to the master control processing board  1054  and controls the rate at which the document being tested is moved through the document channel  1038 . In addition, edge detectors  1062  and  1064  (shown in FIG. 98), which are operatively connected to the master control processing board  1054  by sets of lines  1066  and  1068  and by ribbon connector  1050 , provide information about the position of the document being tested within the document channel  1038 . The electronic verification machine  1000  further includes a bar code reader  1070  which is secured to the frame structure  1002  and is operatively connected to the master control processing board  1054  via connector lines  1072 .  
     [0355]FIG. 98, which is a partially cut-away exploded side perspective view of the electronic verification machine  1000 , shows the relationship among the cover section  1006  of the housing  1004 , the front portion  1034  of the frame structure  1002 , the sensor head  1036 , the tensioning guide  1046 , and the front section  1010  of the housing  1004  in more detail.  
     [0356] The user display panel  1012  and the user interface  1014 , located along the cover portion  1006 , are operatively connected to the master control processing board  1054  via a ribbon connector  1015 . When the electronic verification machine  1000  is fully assembled, the ticket slot  1022  formed in the cover portion  1006  is aligned with the document channel  1038  (shown in FIG. 97) which is formed between the front portion  1034  of the frame structure  1002  and the sensor head  1036 . The pressure roller  1056  extends through an aperture  1074  formed in the front portion  1034  of the frame structure  1002 . Consequently, the pressure roller  1056  contacts the document being tested and moves the document through the document channel  1038  (shown in FIG. 97). In the preferred embodiment, the edge detectors  1062  and  1064  consists of two light emitting diodes  1076  and  1078  and two phototransistors  1080  and  1082 . The light emitting diodes  1076  and  1078  are positioned along the front portion  1034  of the frame structure  1002  on opposite sides of the pressure roller  1056 . The phototransistors  1080  and  1082  are positioned along the sensor head  1036  on opposite sides of a sensor array circuit board  1084  which is secured to the sensor head  1036 . The phototransistors  1080  and  1082  on the sensor head  1036  are aligned with the light emitting diodes  1076  and  1078  on the frame structure  1002  to form the edge detectors  1062  and  1064 . The first edge detector  1062  is used to indicate that a document has been inserted into the electronic verification machine  1000 . The second edge detector  1064  is used to obtain precise document position information. The first edge detector  1062  and the second edge detector  1064  are spaced-apart by a pre-determined distance which, in the preferred embodiment, is about 1.48 inches. In addition, the second edge detector  1064  is located at a pre-determined distance, preferably 0.73 inches, below the tangent point of the pressure roller  1056 .  
     [0357] The electronic verification machine  1000  also includes a window  1086  formed along the front portion  1034  of the frame structure  1002 . The window  1086  is aligned with both the bar code reader  1070  and the mirror  1028  located along the front section  1010  of the housing  1004 . Together, the mirror  1028  and the window  1086  can be used with the bar code reader  1070  to read bar codes that are printed on the front of the document being tested. Alternatively, bar codes that are printed on the back of the document being tested can be read by the bar code reader  1070  and the window  1086  alone. As noted earlier, the electronic verification machine  1000  can also include indicator lights  1030  located on the front section  1010  of the housing  1004 . The indicator lights  1030  are operatively connected to the door position sensor  1029  (shown in phantom) which also is located on the front section  1010  and which, in the preferred embodiment, includes a light emitting diode and a phototransistor. The door position sensor  1029  and the indicator lights  1030  are operatively connected to the master control processing board  1054  by lines  1090  and  1092 , respectively.  
     [0358]FIG. 99 is a block diagram of the relationship among the major components of the electronic verification machine  1000 . The sensor head  1036  is connected to the master control processing board  1054  by the ribbon connector  1050 . The light emitting diodes  1076  and  1078  which form parts of the edge detectors  1062  and  1064 , respectively, are connected to the master control processing board  1054  by the lines  1066  and  1068 , respectively. The door position sensor  1029  is connected to the master control processing board  1054  by the line  1090 , while the indicator lights  1030  are operatively connected to the master control processing board  1054  by the line  1092 . A line  1094  operatively connects the stepper motor  1058  to the master control processing board  1054 . The lines  1072  operatively connect the bar code reader  1070  to the master control processing board  1054 . The user interface  1014  is operatively connected to the master control processing board  1054  by the ribbon connector  1015 . The electronic verification machine also includes a stigmatization circuit  1096  which is used in conjunction with the sensor array  1044  and the master control processing board  1054  to stigmatize a document being tested once its electrical signature has been measured. The stigmatization circuit  1096  is operatively connected to the sensor array  1044  by lines  1098  and to the master control processing board  1054  by lines  1100 .  
     [0359] In the preferred embodiment of the invention, master control processing board  1054  includes two microcontrollers, a support microcontroller  1102  and a primary microcontroller  1104 . The support microcontroller  1102  is used in controlling all low-level device interfaces, such as the sensor array  1044 . the stigmatization circuit  1096 , the edge detectors  1062  and  1064 , the door position sensor  1029 , the indicator lights  1030 , the user interface  1014 , the bar code reader  1070  and the stepper motor  1058 . A set of lines  1106 - 1110  provides signal inputs and outputs to the support microcontroller  1102 . In the preferred embodiment of the invention, the support microcontroller  1102  is a Motorola MC68HC16 processor which incorporates a 16 bit central processing unit, a single chip integration module, a multi-channel communications interface, a general purpose timer and a time processing unit. The support microcontroller also includes an 8 to 10 bit analog-to-digital (A/D) converter  1112  and memory  1114 . The memory  1114  of the support microcontroller  1102  preferably includes 48 Kbytes of Programmable Read Only Memory (PROM) and 65 Kbytes of Static Random Access Memory (SRAM). The bar code reader  1070  is connected to the support microcontroller  1102  by a standard bidirectional UART port operating at 9600 Baud. The internal timers of the support microcontroller  1102  are used to control the stepper motor  1058 . The edge detectors  1062  and  1064  are interfaced to the support microcontroller as standard Transistor-Transistor Logic (TTL) signals.  
     [0360] The primary microcontroller  1104  is used to process the electrical signature of the document being tested in order to verify that the document is authentic. In the preferred embodiment of the invention, the primary microcontroller  1104  preferably is a 32 bit Elan SC410A which operates at an internal clock speed of 66 MHz. The primary microcontroller  1104  also includes memory  1116  which, in the preferred embodiment consists of 4-8 Mbytes of Dynamic Random Access Memory (DRAM), 2-4 Mbytes of flash memory, and 512 Kbytes to 1 Mbyte of SRAM supported by a back up battery. In the preferred embodiment of the invention, the primary microcontroller  1104  includes a glueless burst-mode interface that allows the flash memory to be partitioned in to various sectors, e.g., operating system, operational software version A, operational software version B, etc. The primary microcontroller  1104  is connected to the support microcontroller  1102  by a high speed parallel interface  1118 . A parallel interface  1120  connects the primary microcontroller  1104  to a Dual Universal Asynchronous Receiver-Transmitter (DUART)  1122  which is also connected by a serial digital line at Transistor Transistor Logic (TTL) levels to a modem  1126 . In the preferred embodiment of the invention, the modem  1126  is a 14.4 kbps Rockwell modem. The modem  1126  is used to provide communications between the electronic verification machine  1000  and a central site computer, such as the computer  223  (shown in FIG. 17).  
     [0361] As mentioned earlier, the support microcontroller  1102  is used for all low level device interfaces. Consequently, the primary microcontroller  1104  is used only for high level functionality such as comparing the measured electrical signature to a predetermined game signature map such as shown in FIG. 44. In addition, the primary microcontroller  1104  communicates with the central site computer  223  to obtain game specific information such as the game signature map  632 , and to determine the redemption value of high level probability game lottery tickets, such as the ticket  700 . To maximize communications flexibility with the central site computer, the electronic verification machine can also be equipped with an optional Motorola MC68302 communications processor (not shown). This communications processor would then be used to handle all low-level communications protocols, thereby allowing the primary microcontroller  1104  to focus exclusively on high-level ticket/user functionality.  
     [0362]FIG. 100 is a top plan view of the sensor head  1036  and shows the sensor array  1044  in more detail. The sensor head  1036  includes the phototransistors  1080  and  1082  that form parts of the edge detectors  1062  and  1064  (shown in FIG. 98) and the sensor array circuit board  1084  of which the sensor array  1044  forms a part. In the preferred embodiment, the sensor array circuit board  1084  is secured to a sensor head housing  1128  which also carries the phototransistors  1080  and  1082 . Due to the intimate physical contact between the document being tested and the sensor head  1036 , if not protected the phototransistors  1080  and  1082  can become dirty over time due to contact with the document being tested. Consequently, in the preferred embodiment of the invention, the phototransistors  1080  and  1082  are embedded within and protected by the sensor head housing  1128  which is formed from a plastic that is transparent in the infrared region. In the preferred embodiment, a clear Acrylic with a 94-V0 flame rating is used to form the sensor head housing  1128 .  
     [0363] The sensor array  1044  includes an elongated excitation plate  1130 , thirteen sensor plates  1132 A- 1132 M, and a fuse excitation pad  1134 . It should be noted that, in an embodiment of the invention that does not include stigmatization, the fuse excitation pad  1134  can be replaced with a sensor plate to provide fourteen document sensor channels. The vertical dimension of each of the sensor plates  1132 A- 1132 M preferably is 0.1 inches and the horizontal dimension of each of the sensor plates  1132 A- 1132 M preferably is 0.1 inches. The vertical dimension of the excitation plate  1130 , which preferably is located about 0.05 inches from the sensor plates  1132 A- 1132 M, preferably is 0.1 inches. The horizontal dimension of the fuse excitation pad  1134  preferably is about 0.1 inches and the vertical dimension preferably is about 0.26 inches. The sensor array  1044  can also include a thin ground strap  1136  positioned intermediate the excitation plate  1130  and the sensor plates  1132 A- 1132 M. Because of the close proximity of the excitation plate  1130  and the sensor plates  1132 A- 1132 M, the excitation signal can jump between the excitation plate  1130  and the sensor plates  1132 A- 1132 M, resulting in an inaccurate electrical signature. The ground strap  1136  behaves as an “electrical fence” and prevents signal jumping from the excitation plate  1130  to the sensor plates  1132 A- 1132 M. The inter-sensor plate spacing should be about twice the horizontal dimension of the sensor plates  1132 A- 1132 M. In the preferred embodiment of the invention, the spacing between any two adjacent sensor plates  1132 A- 1132 M, such as the sensor plates  1132 B and  1132 C, is about 0.18 inches. The horizontal dimension of the excitation plate  1130  is chosen so that the excitation plate  1130  spans the distance of the thirteen sensor plates  1132 A- 1132 M. In the preferred embodiment of the invention, the horizontal dimension of the excitation plate  1130  therefore is about 3.46 inches.  
     [0364] The excitation plate  1130 , the sensor plates  1132 A- 1132 M, the fuse excitation pad  1134 , and the ground strap  1136  preferably are made from a highly conductive material, such as copper. However, it has been found that over time the sensor array  1044  can become worn due to the close physical contact of the document being tested. Consequently, in the preferred embodiment of the invention, the excitation plate  1130 , the sensor plates  1132 A- 1132 M, the fuse excitation pad  1134 , and the ground strap  1136  are initially formed as a three-part layer consisting of copper, covered by nickel, covered by a thin layer of gold. The nickel protects the copper surface and protects the sensor array  1044  from undue wear and tear. The thin gold layer allows other parts of the sensor array circuit to be soldered onto the sensor array circuit board  1084 . Over time, the gold layer covering the sensor array elements  1130 ,  1132 A- 1132 M,  1134 , and  1136  wears away leaving only the nickel-coated copper layer. The thin gold layer over the sensor array elements  1130 ,  1132 A- 1132 M,  1134 , and  1136  thus serves as a sacrificial mask while the thin gold layer on other portions of the sensor array circuit board  1084  permits soldering of other sensor head components.  
     [0365] It has also been found that, because of the close physical contact between the sensor array  1044  and the document being tested, irregularities along the top surface  1138  of the sensor array circuit board  1084  can cause the document to become jammed in the document channel  1038  (shown in FIG. 97). Consequently, care must be taken in fabricating the sensor array circuit board  1084  to ensure that the sensor array elements  1130 ,  1132 A- 1132 M,  1134 , and  1136  are essentially flush with the top surface  1138  of the sensor array circuit board  1084 . Preferably, the sensor array elements  1130 ,  1132 A- 1   132 M,  1134 , and  1136  project less than 0.00006 inches from the top surface  1138 . If necessary, a non-conductive epoxy film can be applied to the top surface  1138  to achieve this goal.  
     [0366] The general operation of the electronic verification  1000  to measure the electrical signature and other verification data of a document will now be explained with reference to the ticket  700 , shown in FIG. 49. Referring now to FIGS.  96 - 100 , the document to be tested, such as the ticket  700 , is placed in the document ticket slot  1022  so that the back  822  of the ticket  700  faces the front portion  1034  of the frame structure  1002 . The ticket  700  drops into the document channel  1038  until it reaches the top of the pressure roller  1056 . At this point, the first edge detector  1062  signals the support microcontroller  1102  that the ticket  700  is present in the document channel  1038 . Consequently, the support microcontroller  1102  provides a first pulse rate to the stepper motor  1058  which rotates the pressure roller  1056  at a first rate to move the ticket  700  down the ticket channel  1038  past the sensor head  1036 . In the preferred embodiment of the invention, the stepper motor  1058  advances the ticket  700  in discrete steps of about 0.02 inches per step. The first pulse rate supplied by the support microcontroller  1102  preferably is 300 steps per second. Thus, the pressure roller  1056  initially moves the ticket  700  in the document channel  1038  at a rate of about six inches per second. As soon as the stepper motor  1058  has been activated, the support microcontroller  1102  activates the sensor array circuit board  1084  so that the sensor array  1044  measures the electrical signature of the ticket  700 . The electronic verification machine  1000  measures the electrical signature of the document being tested, such as the ticket  700 , by capacitively coupling an excitation signal from the triangular waveform generator  510  (shown in FIGS. 40, 41, and  101 ) to the document via the excitation plate  1130 . Since there are thirteen sensor plates  1132 A- 1132 M, the sensor array  1044  provides thirteen sensed electrical signature values for each step of the stepper motor  1058 . The thirteen sensed electrical values are forwarded to associated amplifiers. The processed signal is then sampled by the 8-bit A/D converter  1112 . The 8-bit values of the sampled signals are then passed to the primary microcontroller  1104  for analysis.  
     [0367] As the stepper motor  1058  moves the ticket  700  through the document channel  1038  at the first pulse rate, the leading edge of the ticket  700  eventually passes the second edge detector  1064  and thereby activates the second edge detector  1064 . The stepper motor  1058  then continues to move the ticket  700  through the document channel  1038  via the pressure roller  1056  until the support microcontroller  1102  determines that the bar code  730 , which is printed on the ticket identification portion  708  (shown in FIG. 49) of the ticket  700 , is in position for reading by the bar code reader  1070 . The bar code  730  is printed on the ticket  700  at a predetermined position, relative to the leading and following edges of the ticket  700 . Since the ticket  700  moves through the document channel  1038  at a pre-determined rate, in this case a rate of 0.02 inches per step, the location of the leading edge of the ticket  700  involves simply counting the number of stepper motor steps which have occurred since the second edge detector  1064  was activated. Once the ticket  700  is in position for the bar code reader  1070  to read the bar code  730 , the support microcontroller  1102  provides a second pulse rate to the stepper motor  1058  so that the ticket  700  moves at a second pre-determined rate while the bar code  730  is being read. The bar code reader  1070  operates at a pre-determined rate which, in the preferred embodiment of the invention is thirty Hertz. Consequently, the rate at which the ticket  700  moves past the bar code reader  1070  must be slower than the initial rate at which the ticket  700  moves through the document channel  1038  to ensure an accurate reading of the bar code  730 . Therefore, in the preferred embodiment of the invention, the second pulse rate provided by the support microcontroller  1102  is  15  steps per second so that the bar code  730  on the ticket  700  moves past the fixed bar code reader  1070  at a rate of 0.3 inches per second. If the bar code reader  1070  is not able to read the bar code  730 , the stepper motor  1058  continues to move the ticket  700  at the second rate until the support microcontroller  1102  determines that the bar code  730  has moved completely past the bar code reader  1070 . Since the bar code  730  has a pre-determined height, determining that the bar code  730  has moved past the bar code reader  1070  involves counting the stepper motor steps which have occurred since the support microcontroller  1102  initiated the second pulse rate. If the bar code reader  1070  still has not been able to read the bar code  730 , the support microcontroller  1102  stops the stepper motor  1058  and sends a reverse pulse rate to the stepper motor  1058  so that the ticket  700  is moved back out through the document slot  1022 , thereby alerting the operator that the bar code  730  has not been read.  
     [0368] Once the bar code  730  is read by the bar code reader  1070 , the support microcontroller  1102  again sends the first pulse rate to the stepper motor  1070  to move the ticket  700  through the document channel  1038  at the first rate until the following edge of the ticket  700  passes the first edge detector  1062  and thereby inactivates the first edge detector  1062 . The support microcontroller  1102  then calculates the number of additional stepper motor steps needed to move the ticket  700  past the sensor head, based on the pre-determined distance between the first edge detector  1062  and the second edge detector  1054 . The stepper motor  1070  then continues to move the ticket  700  at the first pre-determined rate for the calculated number of stepper motor steps needed for the ticket  700  to clear the sensor head  1102 . At this point, the support microcontroller  1102  deactivates both the stepper motor  1058  and the sensor head  1036 . The measured electrical signature value of the document being tested is then transmitted the primary microcontroller  1104  for verification analysis.  
     [0369] In addition to providing document position information to the support microcontroller  1102  while the ticket  700  is being read by the electronic verification machine  1000 , the edge detectors  1062  and  1064  also provide information which controls how the support microcontroller  1102  responds if the ticket  700  becomes jammed in the electronic verification machine  1000 . For example, the operator may inadvertently place an improperly sized document into the electronic verification machine  1000 . If the document is too short, the first edge detector  1062  can become deactivated before the leading edge of the document passes the second edge detector  1064  and the document can become jammed in the document channel  1038 . The support microcontroller  1102  uses the pre-determined distance between the first edge detector  1062  and the second edge detector  1064  to determine if a short ticket has been inserted into the electronic verification machine  1000 . The number of stepper motor pulses needed to move the leading edge of a document from the first edge detector  1062  to the second edge detector  1064  is pre-determined by the distance between the first edge detector  1062  and the second edge detector  1064  and by the size of each stepper motor step. If the first edge detector  1062  is deactivated before the second edge detector  1064  is activated, the document must be less than  1 . 478  inches long. Once the leading edge of the document activates the second edge detector  1064 , 0.73 inches of the ticket must have moved from the tangent point of the pressure roller  1056  to the second edge detector  1064 , leaving at most 0.75 inches of the ticket to be moved through the document channel  1038  past the second edge detector. As previously stated, the first pre-determined pulse rate moves the document at 0.02 inches per stepper motor step. Consequently, the support microcontroller  1102  continues to provide the first pulse rate to the stepper motor for an 38 additional stepper motor steps, at which time the document should be past the second edge detector  1064  and free of the document channel  1038 .  
     [0370] The edge detectors  1062  and  1064  can also be used to provide data that helps to verify the authenticity of the document being tested. For example, when the document being tested is a probability game lottery ticket, such as the ticket  700 , the size of the ticket  700  can be used to help determine if the ticket is authentic. Once the ticket has passed completely though the document channel  108 , the size of the ticket can be determined by counting the number of stepper motor steps which have occurred between the activation and deactivation of the second edge detector  1064 . The measured value for the size of the ticket  700  can then be compared to a pre-determined value for the size of the ticket  700  to provide an additional parameter by which the authenticity of the ticket  700  can be tested.  
     [0371] B. Determining The Electrical Signature  
     [0372] One of the objects of the electronic verification machine  1000  is to determine the electrical signature of the document being tested. When the document being tested consists of a probability game ticket, such as the ticket  700  (shown in FIG. 49), the electrical signature consists of a two-dimensional array or grid which represents the location and amount of conductive material found on the document. The sensor array  1044  of the electronic verification machine  1000  is used to scan the playing field portion  706  and the ticket identification portion  708  of the ticket  700  to determine the amount and location of conductive materials and to generate a scanned data map or scratch map, such as that shown in FIG. 45. The primary electrical signature value that the sensor array  1044  detects is the total capacitance of the excitation plate  1130  and a given one of the sensor plates  1132 A- 1132 M. In general, capacitance is defined by Maxwell&#39;s equation:  
       C=Kε   0 ( A/T )  
     [0373] where K is the dielectric constant of the insulating material separating the conductive planes of the capacitor, A is the intersecting area of the conductive planes, T is the thickness of the insulating material and ε 0  is the permittivity of free space. When the sensor array  1044  is capacitively coupled to the document being tested, such as the ticket  700 , the excitation plate  1130  and a given one of the sensor plates  1132 A- 1132 M, such as the sensor plate  1132 A, function as two capacitors C 1  and C 2  whose capacitance depends on the nature and amount of conductive material on the portions of the ticket  700  which underlie the excitation plate  1130  and the sensor plate  1132 A.  
     [0374] A simplified partial circuit diagram of the capacitive coupling between the sensor array  1044  and the document being tested, such as the ticket  700 , is shown in FIG. 101. C t1  represents the capacitance between the excitation plate  1130  and the document being tested and C t2  represents the capacitance between the document and one of the sensor plates  1132 A- 1132 M, such as the sensor plate  1132 A. The portion of the ticket  700  which is intermediate the excitation plate  1130  and the sensor plate  1132 A functions as a resistor having a resistance represented by R t  and effectively connects in series the capacitors C 1  and C 2  formed at the excitation plate  1130  and the sensor plate  1132 A, respectively. Consequently, the total coupling capacitance C total  is the combined capacitances of C t1  and C t2 . The magnitudes of C t1  and C t2  depend on the nature and amount of conductive material on the portions of the ticket  700  which underlie the excitation plate  1130  and the sensor plate  1132 A. Referring back to FIGS.  49 - 71 , it will be recalled that the ticket  700  is printed in several different layers. One of the conductive layers printed on the ticket  700 , such the integrity circuit element  740  layer, the indicia circuit elements  732 A- 732 H layer, or the upper blocking layer  830 , serves as the conducting plane in the ticket  700  which operates with the excitation plate  1130  and the sensor plate  1132 A to form the two capacitors C 1  and C 2 . The printed layers which lie between the excitation plate  1130  and the conductive layer and which lie between the sensor plate  1132 A and the conductive layer serve as the insulating medium whose thickness and dielectric constant affect the magnitudes of C t1  and C t2 . The particular conductive layer which forms the conducting plane in the ticket  700  varies depending on the portion of the ticket  700  which is capacitively coupled to the sensor array  1044 , as do the particular layers which form the insulating medium.  
     [0375] It will be recalled that the final form of the ticket  700  includes several different printed layers. The characteristics of the inks used to print the various layers affects the electrical signature measured by the electronic verification machine  1000 . When the electronic verification machine  1000  is used to determine the electrical signature of a probability game ticket, such as the ticket  700 , the preferred first layer  794  (shown in FIG. 52) is an opaque blocking layer that helps to protect the play indica  720 A-H and the circuit elements  732 A-H,  740 ,  750 A, and  750 B, from surreptitious detection by candling. In the presently preferred embodiment of the invention, the first layer  794  ideally is non-conductive relative to conductive layers, such as the layer of integrity circuit elements  740  and the layer of play indicia circuit elements  732 A- 732 H. The presently preferred formulation for the ink used to print the first layer  794  is given in Table 10.  
               TABLE 10                          Ink Formulation for the First Layer 794       (Opaque Blocking Layer 794)                             material   wt %                                         Methyl Ethyl Ketone   56.13           VYHH vinyl resin   5.58           VMCA vinyl resin   17.00           Acrylic resin   3.28           Carbon Black   9.30           Diacetone alcohol   5.00           Sucrose acetate isobutyrate solution   2.50           polymeric surfactant   1.21                      
 
     [0376] The sheet resistivity of the ink described in Table 10 is greater than 20 MΩ/□.  
     [0377] The next layer printed on the ticket  700  contains the integrity circuit elements  740  as well as the data circuit elements  750 A and  750 B. It will be recalled that the integrity circuit elements  740  are used to determine the authenticity and integrity of the ticket identification indicia, such as the bar code  730 , while the data circuit elements  750 A and  750 B are used to provide additional ticket authenticity and integrity information. The ink used to print the data circuit elements  740  and the data circuit elements  750 A and  750 B should be fairly conductive. The presently preferred formulation for the ink used to print the second layer  816  containing the integrity circuit elements  740  and the data circuit elements  750 A and  750 B is given in Table 11.  
               TABLE 11                          Ink Formulation for the Second Layer 816       (the Integrity Circuit Elements 740 and       the Data Circuit Elements 750A and 750B)                             material   wt %                                         Water   38.75           Styrenated acrylic Varnish (J678)   7.00           Dimethylethanol amine   0.25           Acetylenic surfactant   1.00           Defoamer (RS576)   0.25           Carbon Black   15.00           Stryrenated acrylic emulsion (7830)   21.75           Ethyl Alcohol   3.00           Styrenated acrylic emulsion (J89)   8.00           Polyethylene wax dispersion (J28)   5.00                      
 
     [0378] The ink formulation given in Table 11 has a sheet resistivity less than 5 KΩ/□.  
     [0379] Both of the inks used to print the first layer  794  and the second layer containing the integrity circuit elements  740  and the data circuit elements  750 A and  750 B contain carbon black. Consequently, these two layers on the ticket  700  present a dark image. The third layer  818  (shown in FIG. 58) is a masking layer which prevents visual interference from these two layers by masking the lower blocking layer  794 , the integrity circuit elements  740 , and the data circuit elements  750 A and  750 B. The third layer  818  ideally is non-conductive relative to conductive layers, such as the layer of integrity circuit elements  740  and the layer of play indicia circuit elements  732 A- 732 H. A suitable formulation for the third layer  818  was given previously in Table 7 and has a sheet resistivity greater than 10 8  Ω/□. The fourth layer printed on the ticket  700  is a primer layer  820  that provides a suitable surface for printing the play indicia  720 A-H (shown in FIG. 61). The ink used to print the fourth layer  820  should be non-conductive relative to conductive layers, such as the layer of integrity circuit elements  740  and the layer of play indicia circuit elements  732 A- 732 H and preferably has a sheet resistivity greater than 10 8  Ω/□.  
     [0380] The fifth layer printed on the ticket  700  contains the play indicia  720 A- 720 H (shown in FIG. 61). As will be recalled, a standard ink jet printing station is used to print this layer on the ticket  700 . Consequently, this layer is printed with commercially available laser jet inks. The sixth layer  826  (shown in FIG. 63) is a UV seal coat layer that protects the play indicia  720 A- 720 H and the validation number  726  against abrasion. The sixth layer  826  should also be non-conductive relative to conductive layers, such as the layer of integrity circuit elements  740  and the layer of play indicia circuit elements  732 A- 732 H and preferably has a sheet resistivity on the order of 10 8  Ω/□. The seventh layer printed on the ticket  700  is the release coat layer  828  which, as shown in FIG. 64, is printed as discreet layer portions  828 A- 828 H that are associated with the play indicia  720 A and the discrete layer portion  8281  that is associated with the validation number  726 . In order not to interfere with the electrical signatures of the circuit elements  732 A-H,  740 ,  750 A, and  750 B, the electrical conductivity of the release coat layer  828  should be significantly less than the electrical conductivity of the circuit elements  732 A-H,  740 ,  750 A, and  750 B and preferably has a sheet resistivity of 10 8  Ω/□.  
     [0381] The eighth layer printed on the ticket  700  is the opaque upper blocking layer  830  (shown in FIG. 65) that helps to protect the play indicia  720 A-H, the validations number  726  and portions of the circuit elements  732 A-H,  740 ,  750 A, and  750 B against surreptitious detection by candling. The eighth layer  830  preferably is non-conductive relative to the conductive layers on the ticket  700 , such as the layer of integrity circuit elements  740  and data circuit elements  750 A and  750 B and the layer of play indicia circuit elements  732 A- 732 H. An appropriate formulation for the ink used to print the eighth layer (upper blocking layer  830 ) is given in Table 12. This ink formulation has a sheet resistivity of greater than or equal to 20 MΩ/□. This formulation is preferred when the play indicia circuit elements  732 A- 732 H are printed with the ink described in Table 13, below.  
               TABLE 12                          Ink Formulation for the Eighth Layer 830       (Upper Blocking Layer 830)                             material   wt %                                         Conductive carbon black dispersion   30.00           (AGC 2708 Mod III, Merit)           Heptane   16.00           Normal propyl acetate   13.60           Kraton varnish (AGC 2640)   25.00           (a 25% solution of rubber copolymer)           Calcium Carbonate   10.00           PE/PTFE wax blend (PF 150)   3.00           Silicone Emulsion (DC 29)   0.50           Silicone Emulsion (DC 18)   0.90           Maleic rosin ester resin (3330 Varnish,   1.00           Merit)                      
 
     [0382] The play indicia circuit elements  732 A- 732 H (shown in FIG. 68) are printed on the ticket  700  as the ninth layer. The play indicia circuit elements  732 A- 732 H are used to determine the authenticity and integrity of the play indicia  720 A- 720 H. Consequently, the ink used to print the play indicia circuit elements  732 A- 732 H should be fairly conductive. An appropriate formulation for the ink used to print the play indicia circuit elements  732 A- 732 H is given in Table 13. This formulation has a sheet resistivity of less than or equal to 2500 Ω/□ and is particulary useful when the document, such as the ticket  700 , includes a stimatization element, such as an electronic fuse junction  1146  (shown in FIG. 105 and described in more detail below.)  
               TABLE 13                          Ink Formulation for the Ninth Layer       (Play Indicia Circuit Elements 732A-732H)                             material   wt %                                         06-M conductive black base (Merit)   64.00           Colloid acrylic resin (Carboset 1594)   11.00           PE/PTFE wax blend (Polyfluo)   2.00           Ethanol   3.00           Acrylic microspheres (Ropaque OP 96)   5.00           Silicone emulsion (DC 29)   1.50           Surfactant (BYK 348)   0.50           Styrenated acrylic emulsion (Lucidene 604)   10.00           Water   3.00                      
 
     [0383] The tenth layer printed on the ticket  700  is the removable scratch off coating  846 , shown in FIG. 71. The scratch-off coating  846  is printed as a continuous layer that covers the play field portion  706  of the ticket  700  and the validation number  726  within the ticket identification portion  708  of the ticket. To avoid interference with the electrical signatures of the circuit elements  732 A-H,  740 ,  750 A, and  750 B, the electrical conductivity of the scratch-off coating  846  should be significantly less that the electrical conductivity of the circuit elements  732 A-H,  740 ,  750 A, and  750 B and preferably has a sheet resistivity greater than 10 8  Ω/□. Suitable scratch-off coatings are well known in the art.  
     [0384] The eleventh and twelfth layers printed on the ticket  700  are overprint graphic layers, such as the play spot areas  716 A-H, the play spot graphics  718 , the void-if-removed area  722 , and the overprint graphics  724 . These layers help to provide the finished appearance of the ticket  700  as shown in FIG. 49. To avoid interference with the measured electric signatures of the conductive layers on the ticket  700 , such as the second layer, which contains the integrity circuit elements  740  as well as the data circuit elements  750 A and  750 B, and the ninth layer, which contains the play indicia circuit elements  732 A- 732 H, these layers should be relatively non-conductive and preferably have sheet resistivities on the order of 10 8  Ω/□. Suitable overprint graphic inks are well known in the art.  
     [0385] It can thus be seen that the electrical characteristics of the various layers vary from one layer to another, with some layers, such as second layer  816  containing the integrity circuit elements  740  and the data circuit elements  750 A and  750 B or the ninth layer containing the play indicia circuit elements  732 A- 732 H, being relatively conductive while other layers, such as the masking layer  818  or the UV seal coat layer  826  are relatively non-conductive. The electrical characteristics of the layers printed on the ticket  700  in turn can affect the electrical signature measured by the electronic verification machine  1000 . Table 14 summarizes the identity and electrical characteristics of the various layers printed on the ticket  700 .  
               TABLE 14                          Identity and Electrical Characteristics of       Ticket 700 Printed Layers                                 Sheet       Layer Number   Identity   Resistivity               Layer 12   Overprint Graphics   ˜10 8  Ω/□       Layer 11   Overprint Graphics   ˜10 8  Ω/□       Layer 10   Removable Scratch Off Coating 846   ˜10 8  Ω/□       Layer 9   Play Indicia Circuit Elements 732A-732H   ≦2500 Ω/□       Layer 8   Opaque Upper Blocking Layer 830   ≧20 MΩ/□       Layer 7   Release Coat Layer 828   ˜10 8  Ω/□       Layer 6   Seal Coat Layer 826   ˜10 8  Ω/□       Layer 5   Play Indicia 720A-720H   ˜10 8  Ω/□       Layer 4   Primer Layer 820   ˜10 8  Ω/□       Layer 3   Masking Layer 818   ˜10 8  Ω/□       Layer 2   Integrity Circuit Elements 740   &lt;5000 Ω/□       Layer 1   Opaque Blocking Layer 794   &gt;20 MΩ/□                  
 
     [0386] Although the final form of the preferred embodiment ticket  700  includes all of the layers  1  through  12 , specific portions of the ticket  700  may contain only a few of the layers because some of the layers are printed as discontinuous patterns or as discreet layer portions. For example, the ninth layer is composed of the individual play indicia circuit elements  732 A- 732 H and therefore is not a continuous layer. Similarly, the release coat layer  828  is printed as discreet layer portions  828 A- 828 H that are associated with the play indicia  720 A and the discrete layer portion  8281  that is associated with the validation number  726 . Consequently, there are several different printed layer patterns on the ticket  700 , each of which can have different electrical signatures. Variations in the structure of the ticket  700  as described above might be desirable based on the configuration, use, or method of manufacture of such probability-type lottery tickets or similar documents utilizing conductive elements.  
     [0387] The printing sequence described with reference to FIGS.  49 - 77  results in at least three general types of printed layer patterns on the ticket substrate  702 , as shown in FIGS.  102 A- 104 B. Referring to FIG. 102A, a first printed layer pattern  1140  consists of the first opaque blocking layer  794 , the layer containing the integrity circuit element  740 , the masking layer  818 , the primer layer  820 , and the layer containing the bar code  730 . The first printed layer pattern  1140  is formed on the ticket identity portion  708  (shown in FIG. 49) of the ticket  700 . FIG. 102B is a conceptual representation of the two capacitors which are formed when the excitation plate  1130  and the sensor plate  1132 A are capacitively coupled to a portion of the ticket  700  which contains the first printed layer pattern  1140 . The capacitive pick-up area  744  of the integrity circuit element  740  forms the conducting plane in the ticket  700  that couples with the excitation plate  1130  to form the first capacitor. The capacitive pick-up area  742  of the integrity circuit element  740  forms the conductive plane in the ticket  700  that couples with the sensor plate  1132 A to form the second capacitor. The resistive element  746  of the integrity circuit element  740  functions as the resistor that connects the two capacitors in series. The masking layer  818 , the primer layer  820 , and the layer containing the bar code  730  serve as the insulating medium which is interposed between the excitation plate  1130  and the capacitive pick-up area  744  and which is interposed between the sensor plate  1132 A and the capacitive pick-up area  742 . The thickness of the masking layer  818 , the primer layer  820 , and the layer containing the bar code  730  and the dielectric constant of the masking layer  818 , the primer layer  820 , and the layer containing the bar code  730  affect the magnitude of the capacitances C t1  and C t2  formed at the excitation plate  1130  and the sensor plate  1132 A.  
     [0388] A second printed layer pattern  1142 , shown in FIG. 103A, consists of the first opaque blocking layer  794 , the masking layer  818 , the primer layer  820 , the seal coat layer  826 , the upper blocking layer  830 , and the scratch-off coating  846 . The second printed layer pattern  1142  is formed on the playing field portion  706  of the ticket  700  in locations where there are no play indicia, such as the portion of the ticket  700  between the play spot area  716 B and the play spot area  716 C (shown in FIG. 49). FIG. 103B is a conceptual representation of the two capacitors which are formed when the excitation plate  1130  and the sensor plate  1132 A are capacitively coupled to a portion of the ticket  700  which contains the second printed layer pattern  1142 . The upper blocking layer  830  serves as both the conductive plane in the ticket  700  and the resistor which connects the two capacitors in series. The scratch-off coating  846  and any overprint graphics serve as the insulating medium interposed between the excitation plate  1130  and the upper blocking layer  830  and which is interposed between the sensor plate  1132 A and the upper blocking layer  830 . Consequently, the thickness of the scratch-off coating  830  and any overprint graphics and the dielectric constant of the scratch-off layer  830  and any overprint graphics affect the magnitude of the capacitances C t1  and C t2  formed at the excitation plate  1130  and the sensor plate  1132 A.  
     [0389] A third printed layer pattern  1144 , shown in FIG. 104A, consists of the blocking layer  794 , the masking layer  818 , the primer layer  820 , the layer containing the play indicia  720 A- 720 H, the seal coat layer  826 , the release coat layer  828 , the upper blocking layer  830 , the layer containing the indicia circuit elements  732 A- 732 H, and the scratch-off coating  846 . The third printed layer pattern  1144  is formed on the playing field  706  portion of the ticket  700  at each of the play spot areas  716 A- 716 H. FIG. 104B is a conceptual representation of the two capacitors which are formed when the excitation plate  1130  and the sensor plate  1132 A are capacitively coupled to a portion of the ticket  700  which contains the third printed layer pattern  1144 . The capacitive pick-up area  736  of any given indicia circuit element  732 A- 732 H forms the conducting plane in the ticket  700  that couples with the excitation plate  1130  to form the first capacitor. The capacitive pick-up area  734  of the given one of the indicia circuit elements  732 A- 732 H forms the conducting plane in the ticket  700  that couples with the sensor plate  1132 A to form the second capacitor. The resistive element  738  of the given one of the indicia circuit elements  732 A- 732 H serves as the resistor that connects the two capacitors in series. The scratch-off coating  846  and any overprint graphics serve as the insulating medium interposed between the excitation plate  1130  and the capacitive pick-up area  736  and which is interposed between the sensor plate  1132 A and the capacitive pick-up area  734 . Consequently, the thickness of the scratch-off coating  830  and any overprint graphics and the dielectric constant of the scratch-off layer  830  and any overprint graphics affect the magnitude of the capacitances C t1  and C t2  formed at the excitation plate  1130  and the sensor plate  1132 A.  
     [0390] As stated earlier, there are thirteen sensed electrical values for each step of the stepper motor  1058 . The stepper motor  1058  advances the document being tested, such as the ticket  700 , in discreet steps of 0.02 inches each. The number of scan rows for a given document, such as the ticket  700 , can be determined by the following equation:  
     Scan Rows=H/0.02 inches  
     [0391] where H is the height of the document in inches. The thirteen electrical values for each step of the stepper motor  1058  correspond to the C total  across each one of the thirteen sensor plates  1132 A- 1132 M and the excitation plate  1130 . C total  between any given one of the sensor plates  1132 A- 1132 M, such as the sensor plate  1132 A, and the excitation plate  1130  in turn depends upon the nature of the printed layer patern, such as the printed layer patterns  1140 ,  1142 , and  1144 , that underlie the sensor plate  1132 A and the excitation plate  1130 . Each step of the stepper motor  1058  yields thirteen more electrical values, each of which can be different due to differences in the printed layer patterns which underlie each of the thirteen sensor plates  1132 A- 1132 M. The resulting electrical signature is a two-dimensional array or grid, where the x-axis represents the 13 electrical values for each step of the stepper motor  1058  and the y-axis represents the position of the sensor array  1044  in stepper motor steps. The two dimensional array constitutes a scanned data map, such as the scanned data map  634  shown in FIG. 45, which represents the location and amount of conductive material on the tested document.  
     [0392] When the document being tested is a probability game lottery ticket, such as the ticket  700 , the scanned data map, such as the map  634  (FIG. 45), is compared to a game signature map, such as the map  632  shown in FIG. 44, to determine the authenticity of the document. The electronic verification machine  1000  downloads the game signature map from the central site computer via the modem  1126  and stores the game signature map in the memory  1116  of the primary microcontroller  1104 . Each game signature map contains a series of vectors that define information about the sensed electrical values in a given area of the ticket  700 . The area of the vectors is defined as a channel number (x-axis) by stepper motor steps (y-axis). The sensed electrical values are provided by the 8-bit A/D converter  1112  in the support microcontroller  1102 . In the preferred embodiment of the invention, there are three general types of vectors: a Latex Vector, which corresponds to the electrical integrity of the printed layer patterns, such as the patterns  1140 ,  1142 , and  1144 , on the ticket  700 ; a Paper Vector, which is used to determine the thickness of the paper stock of the ticket  700  and to sense an object pushing the Latex Sensor off the paper substrate; and a Ghost Vector, which is used to provide protection against photocopies of the ticket  700 .  
     [0393] The software program that compares the scanned data map, such as the map  634  (FIG. 45) with its associated game signature map, such as the map  632  (FIG. 44) is called Electronic Latex Validation Software or ELVIS. ELVIS is stored in the flash memory portion of the memory  1116  in the primary microcontroller  1104 . After the ticket  700  has been successfully scamied by the electronic verification machine  1000 , ELVIS is called to analyze the scanned data map of the ticket  700 . ELVIS begins by extracting the first three digits of the bar code to determine the game number of the ticket  700 . ELVIS uses the extracted game number to find the associated game signature map in the SRAM portion of the memory  1116  of the primary microcontroller  1104 . If there is no game signature map for the extracted game number, ELVIS aborts processing the ticket  700  and transmits a No Signature Map error message to the display panel  1012 . The operator is then prompted to manually enter the three-digit security number of the ticket  700  via the numeric keypad  1018 .  
     [0394] Once ELVIS has retrieved a game signature map that corresponds to the document being tested, such as the ticket  700 , ELVIS then counts the total number of scan rows to determined the size of the ticket  700 . If the ticket is found to be too big or too small, ELVIS aborts processing the ticket and transmits a Ticket Too Big/Small error message. However, if the size of the ticket  700  is acceptable, ELVIS then analyzes the three vector types for the ticket  700 . The testing criteria used by ELVIS depends on the vector type. For Latex Vectors, Elvis first adds all latex vectors together to determine the total “Play area.” After the total “Play Area” is determined, ELVIS applies a minimum and maximum pixel count criteria to determine if the total “play area” is in compliance. Alternatively, in some circumstances a maximum pixel count alone can suffice. For Paper and Ghost Vectors, ELVIS will reject the ticket  700  if the testing criteria for either of these vectors is not met. ELVIS first analyses the Paper Vectors areas of the ticket  700  to determine if the signals are acceptable. Assuming that there are no Paper Vector errors, ELVIS will sum all of the Latex Vectors to determine the status of the printed layer patterns, such as the patterns  1140 ,  1142 , and  1144 , within the play field portion  706  of the ticket  700 . If the Latex Vectors are found to be acceptable ELVIS examines the Ghost Vectors of the ticket  700  to determine if some of the removable scratch-off coating  846  remains in any played portion of the ticket  700 . If all of the above vector tests are passed, ELVIS concludes that the ticket  700  is authentic and has been validly played.  
     [0395] C. Stigmatization  
     [0396] In addition to measuring the electronic signature of the document being tested, the electronic verification machine  1000  also can stigmatize the document. As explained earlier in Section VI., stigmatization refers to a process by which a document, such as the ticket  700 , which has already been tested by the electronic verification machine  1000  is “marked.” In the case of game tickets, such as the ticket  700 , stigmatization prevents winning tickets from being presented multiple times to be paid. A successful stigmatization scheme has several attributes. The stigmatization should be automatic: if human intervention is required to stigmatize the document errors can occur when the stigmatization is not done correctly. The stigmatization should also be difficult to circumvent. Preferably, the stigmatization equipment should require minimum maintenance. In addition, the stigmatization preferably permits monitoring of tested documents so that attempts at fraudulent redemption can be detected. Consequently, it is desirable that the stigmatization be difficult to detect.  
     [0397] Currently accepted practices for stigmatizing a game ticket, such as the ticket  700 , include visually marking the ticket, for example by stamping the ticket with the words “PAID VOID”. Alternatively, it is common for winning tickets to be destroyed once they have been redeemed. However, since both of these stigmatization schemes require human intervention, the possibility exists that a winning ticket will not be stigmatized correctly and can then be presented multiple times for payoff. In addition, these stigmatization schemes do not permit monitoring of paid tickets so that attempts at fraudulent redemption can be detected. Another accepted practice is to maintain a paid ticket file in a central computer. Although such a scheme does not necessarily require human intervention and cannot be easily detected, such a stigmatization scheme requires that the ticket redemption terminal maintains a constant link with the central computer and such on-line linkages can be quite costly. As mentioned previously in Section IV., another method for stigmatizing a ticket involves automatically colorizing at least a portion of the ticket once it has been presented for redemption. For example, a portion of the document could be printed with an invisible ink that is thermally sensitive. Once the ticket is presented for redemption, power applied by the ticket terminal could be used to generate sufficient heat to change the color of the invisibly printed portion, thereby automatically stigmatizing the ticket. This scheme, however, has several disadvantages. The stigmatization is not difficult to detect, consequently this stigmatization scheme does not permit monitoring of paid tickets so that attempts at fraudulent redemption can be detected. Moreover, since heat is used as the method for activating the invisible ink and stigmatizing the ticket, heat sources other than the lottery terminal can inadvertently result in ticket stigmatization, for example, when the ticket is left in a closed car on a hot day.  
     [0398] Referring back to FIG. 100, the fuse excitation pad  1134 , together with the sensor pad  1132 M of the sensor array  1044  in the electronic verification machine  1000  can be used to electronically stigmatize a document, such as the ticket  700 . The fuse excitation pad  1134  provides a high voltage excitation signal which is used to alter the state of a printed circuit element on the document. An example of a printed circuit element that can be electronically altered by the electronic verification machine  1000  is shown in FIG. 105, where the printed circuit element is an electronic fuse junction or fuse  1146 . The electronic fuse junction  1146  includes an excitation pick-up area  1148  and a sensor pick-up area  1150  connected by a fuse link  1152 . As explained in more detail below, the electronic verification machine  1000  provides sufficient energy to the electronic fuse junction  1146  via the fuse excitation pad  1134  (shown in FIG. 100) to open the fuse link  1152  between the excitation pick-up area  1148  and the sensor pick-up area  1150 . As described in detail below, direct measurement circuitry in the electronic verification machine  1000  has the capability of checking the state of the electronic fuse junction  1146 . An open electronic fuse junction  1146 , where the fuse link  1152  is not present, normally indicates that the document has already been tested by the electronic verification machine  1000 . On the other hand, a closed electronic fuse junction  1146  indicates that the document has not been previously tested by the electronic verification machine  1000 .  
     [0399] An important feature of the electronic fuse junction  1146  is that it changes its binary status, from closed to open, when the electronic verification machine  1000  applies an energy pulse via the fuse excitation pad  1134 . Therefore the composition and configuration of the electronic fuse junction  1146  is selected such that the electronic fuse junction  1146  changes its binary status upon receipt of the energy pulse rather than simply absorbing the energy pulse through, for example, heat transfer to the substrate or other materials on the document. It is desirable to make the time duration of the energy pulse provided by the electronic verification machine  1000  as short as possible, for example, on the order of 0.1 seconds. By the same token, to minimize heat transfer to the ambient surroundings the fuse link  1152  should be as small as possible. In addition, the electronic fuse junction  1146 , including the fuse link  1152 , preferably is formed from a material that has a reasonably high resistance so that the current flow through the fuse link  1152  will generate enough heat to break the conductive path.  
     [0400] When the electronic fuse junction  1146  is printed on probability game tickets, such as the ticket  700 , there are additional attributes that the electronic fuse junction  1146  should have. For example, the electronic fuse junction  1146  should be formed from a material that is not hazardous to the environment or to humans. The electronic fuse junction  1146  also should be formed from a material that can be printed with a Gravure, Offset, or Lithograph printing press. It is also desirable that the electronic fuse junction  1146  should be formed from a material which is already being used on the ticket  700 , to avoid having to add an additional printing station.  
     [0401] In one example, the electronic fuse junction  1146  is printed on the document using an ink that has a sheet resistivity in a range of from about 800 Ω/□ to about 2.4 KΩ/□. Preferably, the ink used to print the electronic fuse junction  1146  has a sheet resistivity on the order of 2.4 KΩ/□. Along with the above discussed criteria, the dimensions of the fuse link  1152  are determined by a number of additional factors, including by the printing press resolution, the characteristics of the ink used to print the electronic fuse junction  1146 , the dimensions of the sensor plates  1132 A- 1132 M in the sensor array  1044 , and the characteristics of the substrate on which the electronic fuse junction  1146  is printed. In the example of the electronic fuse junction  1146  printed on a probability game ticket, such as the ticket  700 , the vertical dimension of the excitation pick-up area  1148  preferably is about 0.24 inches, as is the vertical dimension of the sensor pick-up area  1150 . The horizontal dimension of the excitation pick-up area  1148  preferably is about 0.10 inches, as is the horizontal dimension of the sensor pick-up area  1150 . The vertical dimension of the fuse link  1152  preferably is about 0.02 inches and the horizontal dimension of the fuse link  1152  preferably is about 0.05 inches. In addition, when the electronic fuse junction  1146  is printed on a probability game ticket, such as the ticket  700 , the electronic fuse junction  1146  can be printed on the ticket  700  with the same ink used to print the play indicia circuit elements  732 A- 732 H (shown in FIG. 50). Therefore, an additional printing station is not needed to print the electronic fuse junction  1146  on the ticket  700 . When the electronic fuse junction  1146  is printed with an ink that has a sheet resistivity of 2.4 KΩ/□, for example, the ink formulation desribed in Table 13, and has the aforementioned preferred dimension the fuse link  1152  has a resistance between 6 KΩ and 16 KΩ that opens reliably with the application of 0.1 joules of energy expended in 0.1 second or less. It should also be pointed out that the electronic fuse junction  1146  can be printed with the same ink used to print the circuit elements on the probability game ticket  700  or with the upper conductive black ink on a conventional lottery ticket.  
     [0402] The functional block diagram of FIG. 106 illustrates the stigmatization circuit  1096  that can be used to stigmatize a document such as the probability ticket  700  having the electronic fuse junction  1146  of the type shown in FIG. 105. As indicated above, it has been found that the application of 0.1 joules of energy to the electronic fuse junction  1146  in approximately 0.01 seconds is enough to reliably open the fuse link  1152 . To expend 0.1 joules in 0.01 seconds requires 10 watts of average power. Power in a resistor is equal to the product of the resistance and the square of the current through it. For a 16,000 Ω resistor such as the fuse link  1152 , the required current is:  
     (10/16000) 1/2 =25 mA  
     [0403] The voltage across a resistor is equal to the product of the resistance and the current through it. In this example, the required voltage is then:  
     16000×0.025=400 volts  
     [0404] Thus it is possible to open a 16 KΩ fuse junction by applying 400 volts DC to the junction. Most 10-watt, 400-volt supplies, however, are large and expensive. However, storing the energy in a capacitor, such as a capacitor C 1  as shown in FIG. 106, over a relatively long time period, at a relatively low charging rate, and discharging the capacitor into the electronic fuse junction  1146  quickly can substantially reduce the size and cost of the supply. The energy stored in a capacitor is equal to:  
     Energy stored in cap.=½CE 2  joules  
     [0405] Solving for C,  
       C= (2 E )/ V   2    
     [0406] With E=0.1 joules and V=400 volts, C min =1.25 μF. Since 1 μF capacitors are more available than 1.25 μF capacitors, the above formula suggests the use of a voltage V of at least 470 volts. With a voltage V of 500 volts the total capacitor energy will be 0.125 joules. In this case, it will take approximately 13 ms to apply 0.1 joules of energy into the fuse link  1152  which is significantly below the desired 100 ms indicated above.  
     [0407] It is possible to provide a 500 voltage supply that runs continuously or a voltage supply that turns on when the leading edge of a ticket passes the first edge detector. The advantage to having the voltage supply constantly operating is that the electronic fuse junction  1146  could be located anywhere on the ticket  700 , including the leading edge. On the other hand, if the voltage supply is off until needed, the electronic fuse junction  1146  should be located near the end of the ticket to allow the storage capacitor time to be charged. Assuming the tickets  700  are fed into the machine  1000  one after the other, the supply should be able to recover in the time required to process a 2-inch long ticket. Given that the stepper motor moves the ticket  700  at 0.02-inch per step at approximately 300 steps per second, 0.5 seconds is available to charge the capacitor C 1 . Where the capacitor C 1  is charged with a constant current and the actual values are V equal to 500 volts and C 1  equal to 1 μF, total capacitor energy will be 0.125 joules. Approximately 13 ms are required to dump 0.1 joules into the 16,000 Ω resistor  1152 . This time is well below 100 ms. Also since:  
       I=C ( dv/dt )  
       I= (0.5)(1.0×10 −6 )/0.5=1 mA  
     [0408] The maximum output power from the supply is thus:  
     P=IV  
       P= 500×0.001=0.5 watts  
     [0409] which is 20 times smaller than the 10-watt power supply mentioned above.  
     [0410] It should be understood that voltage converter topology presents a variety of choices. It is possible to use a push-pull converter, boost converter, or flyback converter. In this case, there is no particular advantage to transformer isolation and the output power is low enough to make push-pull unnecessary. In order to reduce the cost of the voltage supply, a simple boost power supply using a Texas Instruments (TI) TL497 controller  1154 , an off-the-shelf inductor, and 1 μF storage capacitor C 1  are used in the preferred embodiment of the invention shown in FIG. 106. The supply  1154  normally will require 0.3 seconds to produce 500 volts on the capacitor C 1 .  
     [0411] Operation of the stigmatization circuit  1096  shown in FIG. 106 will now be described in connection with the operation of the electronic verification machine  1000 . The supply  1154  is activated by a signal (from the support microcontroller  1102 ) on an inhibit line  1156  which converts a 12 volt DC voltage on a line  1158  from the system power supply (not shown) to a  500  volt voltage on an input line  1160  to the capacitor C 1 . The electronic fuse junction  1146  is moved by the stepper motor  1058  into position between the fuse excitation plate  1134  and the sensor pad  1132 M. A voltage divider including a resistor R 3  and the fuse link  1152  along with a diode D 1  respond to a 5 volt signal on a line  1162 , from the system power supply (not shown), to apply a voltage on a link monitor line  1164  which in turn is input to an analog to digital converter (not shown) on the support microcontroller  1102 . In the event that the fuse link  1152  is open, indicating that the ticket  700  might have already been stigmatized, a voltage of 5 volts will appear on the link monitor line  1164 . On the other hand, if the fuse link  1152  is still present and ignoring the resistance in the fuse link  1152  and the resistor R 3 , a small voltage, for example 0.6 volts will appear on the link monitor line  1164  due to the resistance in the diode D 1  and a diode D 2 . However, if the resistor R 3  has a value equal to the value of the fuse link  1152  resistance, for example 16,000K Ω, then the voltage on the link monitor line  1164  will be about 2.8 volts. One advantage of the invention is that by printing the fuse link  1152  with a known value, it is possible to significantly reduce the possibility of counterfeits by in effect measuring the resistance value of the fuse link  1152 .  
     [0412] In one embodiment of the invention, once the value of the resistance of the fuse link  1152  is determined, the voltage of the output of the power supply  1154  can be measured using a voltage divider including a pair of resistors R 1  and R 2 . The output of this voltage divider is applied over a high voltage monitor line  1166  to the analog to digital converter (not shown) on the support microcontroller  1102 . In this manner it is possible for the support microcontroller  1102  to determine if there is sufficient charge on the capacitor C 1  to blow the fuse link  1152 . When the voltage on the capacitor C 1  has reached a predetermined value, such as 470 volts, this voltage is applied to the fuse link  1152  via a switch SW 1  and over the fuse excitation plate  1134  and the sensor pad  1132 M. The switch SW 1  can be a field effect transistor under control of the support microcontroller  1102  via a line  1166 . It should be noted that the diode D 1  serves to protect the link monitor line  1164  from the high voltage on the capacitor C 1 . Also, in this circuit  1096 , the diode D 2  prevents the current in the fuse link  1152  from pulling the pad  1132 M to more than 0.7 volts above ground.  
     [0413] One of the advantages of the circuit  1096  shown in FIG. 106 is that the plate  1132 M can be used as both a sensor plate for sensing the various criteria in the ticket  700  as described above and as ground plate for stigmatizing the ticket  700 . Here a switch SW 2 , which also can be a field effect transistor, is switched on at the same time the switch SW 1  is closed in response to the stigmatization signal on the line  1166 . This prevents the current in the fuse link  1152  from returning to the sensor excitation circuit.  
     [0414] In the preferred embodiment, after the stigmatization voltage has been applied from capacitor C 1  to the electronic fuse junction  1146 , the switches SW 1  and SW 2  are opened and the support microprocessor  1102  measures the voltage on the link monitor line  1164 . If the voltage on this line is 5 volts, indicating that the fuse link  1152  might have been blown, the ticket  700  is advanced by the stepper motor  1058  one step or 0.02 inches. The support microcontroller  1102  again measures the voltage on the link monitor line  1164  and if the voltage is significantly below 5 volts, the stigmatization process is initiated again. After five such steps without a significant drop in the voltage on the link monitor line  1164 , it is assumed that the fuse link  1152  has been successfully blown. At this point, the stigmatization process has been completed and the high voltage power supply  1154  is inhibited by a signal on line  1156 . One advantage of using an electronic fuse junction having dimensions larger than the excitation plate  1134  and the sensor plate  1132 M, is that it is possible to test the fuse link  1152  over a number of steps to ensure that it has been opened.  
     [0415] The following is the preferred criteria for using the circuit such as the circuit  1096  in the electronic validation machine  1000  to stigmatize lottery tickets. Losing tickets can be stigmatized although there is no apparent advantage to doing so. Conversely, it is not apparent that there is any particular disadvantage to stigmatizing a losing ticket. Therefore, losing tickets will be stigmatized. Winning tickets should be stigmatized. In the event of a barcode misread, the ticket preferably should not be stigmatized. The electronic validation machine  1000  should back the ticket out and request a rescan. The ticket may have been inserted backward or upside down.  
     [0416] With respect to improperly played tickets, the general conclusion is to stigmatize all of them. Regarding counterfeit tickets and tickets that have been tampered with, as detected by measuring the electrical properties of the fuse link  1152  as described above, the ticket should not be stigmatized. Rather the ticket should be retained by the lottery agent and submitted for analysis.  
     [0417] D. Document Thickness Measurement  
     [0418]FIG. 107 illustrates another significant feature of the electronic validation machine  1000  which is the capability of measuring the thickness t of the substrate of a lottery ticket and similar type documents. This feature will be described in connection with the lottery ticket  700 .  
     [0419] As discussed above, the primary electrical signature value that the electronic validation machine  1000  utilizes is capacitance. Factors influencing capacitance listed below:  
       C=Kε   0 ( A/t )  
     [0420] where:  
     [0421] C=Capacitance (in Farads)  
     [0422] K=Dielectric Constant  
     [0423] A=Area of Electrodes (inches 2 )  
     [0424] t=Electrode Spacing−dielectric thickness (inches)  
     [0425] ε 0 =Constant−0.225 Farad/inch  
     [0426] When there are no conductive or semiconductive ink films located beneath the sensor head  1036  shown in FIG. 100, the electrical waves produced by the excitation bus bar  576  will penetrate through the substrate of the document such as ticket  700  and appear to reflect off of the pressure roller  1056  as indicated by a pair of arrows  1168  and  1170 . Also, it should be noted that it is desirable that the pressure roller be insulated from ground to achieve this reflection effect. The reflected signal is absorbed by the channel sense capacitors  1132 A- 1132 M and can be processed as an electrical signature for the ticket&#39;s paper stock by electronic validation machine  1000  as described above. Thus, electronic validation machine  1000  can evaluate the thickness (t) of a ticket&#39;s paper substrate as well as the composition (K) of the substrate. For the frequency range of the electrical illuminating signal used in electronic validation machine  1000  as indicated above, the dielectric constant of typical paper stock (K p ) will range between:  
     K p : 3.29≦K p ≦4.8  
     [0427] As a practical matter this relative small dielectric range (1.51) for ticket paper substrates in itself has minimal impact on ticket security determination in this particular example. However, evaluation of the thickness t of the substrate can be very important to lottery ticket security. The electronic validation machine  1000  will normally read a lottery ticket&#39;s barcode to determine if the ticket  700  has winning indicia printed under its scratch-off latex. On a traditional scratch-off lottery ticket, the barcode is almost always printed on the back of the ticket. Therefore, it is possible to defraud the lottery by securing an unplayed ticket behind a properly played ticket and feeding both ticket through the electronic validation machine  1000  assuming that the electronic validation machine  1000  will scan the latex of the front ticket and the barcode on the back of the ticket.  
     [0428] However, by measuring the thickness t of the substrate  702  of the lottery ticket  700  at the trailing edge of the ticket where no conductive materials are located, it is possible to determine if additional material such as another ticket has been added to the ticket undergoing validation. As illustrated in FIG. 107, when scanning non-latex areas of a scratch-off the ticket  700 , the paper substrate  702  functions as a large part of the coupling capacitor&#39;s dielectric. Because both the thickness (t) and dielectric constant (K) of a capacitor&#39;s dielectric affect the coupling capacitance and because the dielectric constant for a ticket&#39;s paper substrate (K p   4767 ) does not vary over a significant range and because the capacitance C is divided by the thickness (t) of the dielectric of the coupling capacitor increasing the influence of the dielectric&#39;s thickness (t) on the sensed coupling capacitance, the electronic validation machine  1000  can easily detect an additional ticket between the front ticket  700  and the pressure roller  1056 . For example, the coupling capacitance sensed by the electronic validation machine  1000  for a single 10 point (0.01 inch) ticket substrate would be approximately:  
       C=Kε   0 ( A/t )  
       C= 4ε 0 (0.1/0.01)  
     C=40ε 0    
     [0429] As a result, the coupling capacitance sensed by the electronic validation machine  1000  for a ticket having a substrate double the thickness of the substrate  702  of the lottery ticket  700  would be one-half of the value measured for a single ticket:  
       C= 4ε 0 (0.01/(2×0.01))  
     C=20ε 0    
     [0430] Thus, the change in the sensed capacitance C and therefore a difference in the thickness (t) is readily detectable by the electronic validation machine  1000 .  
     [0431] The composition of the pressure roller  1056  is important in making it electrically reflective. For example, if the pressure roller  1056  is made out of a typical rubber compound with carbon particles embedded in the rubber, the direct current (dc) resistivity of the pressure roller (ρ roller ) has a very high value:  
     ρ roller &gt;2MΩ/cm  
     [0432] This is not surprising because this roller is primarily made of a rubber binder surrounding numerous carbon particles. Rubber is a commonly used insulator and has a very high dc resistivity:  
     ρ rubber : 8×10 12 ≦ρ rubber ≦2×10 15  Ω/cm  
     [0433] Carbon, on the other hand has a relatively low resistivity (ρ carbon ):  
     ρ carbon ≈35 KΩ/cm  
     [0434] This composite roller has a very high dc resistivity because its numerous carbon particles are encapsulated in the high resistivity rubber binder. Therefore, there is no low resistance dc path from one carbon particle to another.  
     [0435] However, this arrangement of carbon particles encapsulated by very thin films of rubber (micron level) causes the composite roller to exhibit a very high dielectric constant, K roller &gt;&gt;300. Apparently due to the close proximity of conductive carbon particles insulated by thin films of rubber which create a 3-dimensional network comprised of a large number of capacitors. Thus, the network consists of numerous microscopic capacitors in a complex arrangement of series and parallel Resistance Capacitance (RC) circuits.  
     [0436] For the excitation frequency range used in the electronic validation machine  1000 , the dielectric constant of rubber compounds, excluding polysulfide rubber (K=2260), ranges from a low of 2.38 (Butyl rubber) to a high of 6.60 (Neoprene rubber). Assuming a rubber dielectric of K=6.60 (for neoprene,) the capacitance between the carbon particles would not be large unless the thickness of the dielectric is very small. Preferably, the best way to obtain small dielectric spacing is with high carbon loading, that is the percentage of carbon particles relative to rubber binder contained in the composite roller material. By increasing the percentage of carbon particles relative to rubber binder the spacing between the individual carbon particles will be reduced. Thus, it is believed that the very small spacing between the conductive carbon particles causes the pressure roller to effectively exhibit an extremely high dielectric constant. As a result, the preferred composition of the pressure roller  1056  is a nonconductive elastomeric material, such as rubber, encapsulating a large number of conductive particles, such as carbon.  
     [0437] XIII. Other Applications Of The Invention  
     [0438] The present invention is not limited to validating or determining the authenticity and integrity of probability game, pull-tab or other types of lottery tickets, but is applicable in many circumstances in which bar code readers and magnetic stripes are used. For example a document such as a stock certificate could be printed with electronic circuits similar to the resistors  82 - 96  printed on the lottery ticket  50  where the electrical signatures of the circuits represent verification data such as a serial number. Human readable document data such as the serial number would also be printed on the stock certificate. The electronic verification machine  108  or  500  would then electrically couple with the circuit elements as described above to generate a verification signal representing the electrical signatures and hence the verification data. Authentication of the certificate is then accomplished by the processor board  220  or terminal  532  which relates or compares the verification signal to a data signal representing the document data. The data signal can be generated by an optical character reader or a user interface such as the keyboard  178 . In this manner the electronic document machine can verify that the serial number printed on the certificate is the correct one for the certificate and thus authenticate the document.  
     [0439] It will then be appreciated that the present invention will have utility in a variety of areas including coupon redemption, inventory security, airport tracking systems, magnetic stripes, currency security, compact disk security, drivers license and passport security. Coupon fraud is a serious problem for the retail industry. Current estimates of money lost to coupon fraud range in the hundreds of millions of dollars. Moreover, with the advent and growth of desk-top publishing and color-photocopiers, the opportunities for coupon fraud as well as other types of document fraud will increase. The present invention can be used to stem the growth of coupon fraud. Providing coupons with an electrical signature by printing at least a portion of an electric circuit on the coupons, according to the invention, would provide the ability to verify the authenticity of the coupons submitted for payment. Further, by utilizing the stigmatizing technique described above it will be possible to prevent coupons from being redeemed more than once. As to inventory security, the circuits according to the present invention can be printed directly on an inventory ticket, price tag or manufacturer&#39;s tag thus supplanting the use of metal strips and coils. Airline ticket fraud, which may also cost hundreds of millions of dollars annually, present another application for the present invention. Circuits according to the present invention could be used to ensure the authenticity and integrity of airline tickets. In addition, the present invention could be used to track the luggage associated with airline travel. The present invention can also be used as an effective alternative to magnetic stripes. Magnetic stripes contain identification numbers, for example, credit card numbers, that are programmed at manufacture. The stripes are prone to failure and are subject to fraud because they are easily copied or modified. To overcome these shortcomings, circuits according to the present invention could be printed on a substrate and encoded with specific customer information. Thus the present invention can be used to improve the security of credit cards, automatic teller machine (“ATM”) cards, and any other tracking card which uses magnetic stripes as a security measure. The present invention can also be used to mitigate the losses resulting from currency fraud which includes, for example, counterfeit currency, and check forgery. Counterfeiting of these documents could be reduced if the documents were provided with an electrical signature or conductive fibers as described above. The invention could be used in the same manner to improve the security of drivers licenses and passports. The invention could also be used to provide inventory control of compact disks which, because of their small size, are subject to theft. Circuits according to the present invention, which included RF devices, could be used to track the compact disks and to prevent their clandestine removal.  
     [0440] Although the present invention has been described with reference to preferred embodiments, it will be understood that various changes and modifications will be suggested to one skilled in the art and it is intended that the invention encompass such changes and modifications as fall within the scope of the appended claims.