Compound secure optical identification method and means

[0002] 1. Field of the Invention

[0003] The present invention relates to secure identification generally and, more particularly, but not by way of limitation, to unique identification method and means that employ a compound diffraction grating strip having first and second identification indicia encoded therein.

[0004] 2. Background Art

[0005] Identification has become increasingly more important in a variety of settings. For example, employee identification cards may be used to gain access to security areas of a facility and/or in time and attendance reporting. Drivers' licenses are often used to verify the identification of the possessors thereof. Various types of credit and debit cards are employed to make purchases, obtain cash or traveler's checks, and/or to transfer funds, for example. In all of these settings, forgery and copying of such identification means result in the compromising of secret information and the loss of hundreds of millions of dollars worth of merchandise and cash annually. In many cases, credit card type identification is verified at the point of sale; however, as the need for more unattended credit card use expands, there is a greater need to verify the authenticity of the credit card to which the transaction is being charged.

[0006] One of the major methods used by forgers of credit cards is to obtain the numbers encoded on a valid credit card during a legitimate transaction and, at a later time, to include this number on another credit card. When the forged credit card is subsequently used on a transaction, the charge is applied to the valid number and the account of the owner of the valid credit card is charged accordingly. The only way to prevent this type of theft is to computer validate each transaction as the purchase is taking place and to have a cashier check the identification of the person purchasing the items against the name returned by the validation computer. While this procedure is economically justifiable when the purchase is for a relatively large amount and there is a cashier present, it is impossible to use this method for small transactions such as with vending machines, pay telephones, transit charges, automatic teller machines, and a host of other unattended charge applications.

[0007] There have also been elaborate attempts to create graphic patterns embellished with holographic photographic images to prevent forged credit cards from easily being produced. However, with today's high-tech criminal element, credit cards and holographic images can be illegally produced and sold at high profits. In addition, this method of security still depends on the human element to inspect the card and identify the holder and to cancel the transaction, if necessary, something not appreciated by most physically exposed cashiers or clerks.

[0008] There have been a number of attempts to create secure identification means involving optical and/or magnetic information recorded on identification means. For example, in U.S. Pat. No. 5,627,663, issued May 6, 1997, to David J. Horan and James S. Bianco, and titled SECURE OPTICAL IDENTIFICATION METHOD AND MEANS, there is described a method of providing secure identification for an article, including: providing on the article a diffraction grating strip including a pattern of a series of diffraction grating elements, each the diffraction grating element to diffract light, from a light source, in one of at least three selected different planes; serially illuminating the diffraction grating elements, detecting changes in plane of diffracted light as the diffraction grating elements are serially illuminated, and generating first information representative of the changes in plane; storing the first information representative of the changes in plane; subsequently, serially illuminating the diffraction grating elements, detecting changes in plane of diffracted light as the diffraction grating elements are serially illuminated, and generating second information representative of the changes in plane; and then, comparing the first and second information to determine the authenticity or not of the article.

[0009] In a further aspect of the invention, a coded pattern of bars, or a bar code, is overprinted on the diffraction grating strip, with one of said coded pattern and the pattern of diffraction grating elements precessing with respect to the other and the coded pattern is read, stored, and compared as part of said first and second information, as above.

[0010] While the identification method and means described in the above-referenced patent have proved to be generally satisfactory, a problem can sometimes arise in which the overprinting of the bar code causes some of the diffraction grating elements to be too narrow. Except for the method and means described in the foregoing patent, none of such known identification means provides a high level of protection against forgery and/or copying. Also, many such identification means do not provide a high degree of assurance that duplicate identification means will not be issued to two or more users.

[0011] Accordingly, it is a principal object of the present invention to provide identification method and means to ensure that an identification is authentic and not a forgery and to make this verification without human intervention.

[0012] It is a further object of the invention to provide such method and means that makes it extremely difficult to duplicate or forge identification means.

[0013] It is an additional object of the invention to provide such method and means that is economical.

[0014] It is another object of the invention to provide such method and means that does not require precise overprinting of a second code.

[0015] It is yet a further object of the invention to provide such method and means that does not require host computer support.

[0016] It is yet an additional object of the invention to provide such method and means that renders highly unlikely that duplicate identification means will be issued to two or more users thereof.

[0017] Other objects of the present invention, as well as particular features, elements, and advantages thereof, will be elucidated in, or be apparent from, the following description and the accompanying drawing figures.

[0018] The present invention achieves the above objects, among others, by providing, in a preferred embodiment, a method of providing secure identification for an article, comprising: providing on said article a diffraction grating strip comprising a pattern of a series of diffraction grating elements, each said diffraction grating element to diffract light, from a light source, in one of at least first, second, third, and fourth selected different planes, each adjacent pair of said diffraction grating elements which diffract light in said first, second, third planes being separated by a diffraction grating element which diffracts light in said fourth plane; and selectively obliterating selected ones of said diffraction grating element which diffract light in said fourth plane, such as to form a binary number consisting of obliterated and non-obliterated ones of said diffraction grating elements which diffract light in said fourth plane.

[0019] Understanding of the present invention and the various aspects thereof will be facilitated by reference to the accompanying drawing figures, submitted for purposes of illustration only and not intended to define the scope of the invention, on which:

[0020] FIG. 1 is an enlarged, fragmentary, perspective view of an identification card with a secure optical identification illustrating one known type of optical identification.

[0021] FIG. 2 is an enlarged, fragmentary, perspective, schematic view of an apparatus for reading the optical identification of FIG. 1.

[0022] FIGS. 3 and 4 are enlarged, top plan views illustrating how the apparatus of FIG. 2 reads the optical identification of FIG. 1.

[0023] FIG. 5 is a top plan view indicating how an identifying number is derived for the optical identification of FIG. 1.

[0024] FIG. 6 is an enlarged, fragmentary, top plan view indicating how an additional identifying number is derived for the optical identification of FIG. 1.

[0025] FIG. 7 is an enlarged, fragmentary, perspective view indicating how the apparatus of FIG. 2 reads the additional identifying number of FIG. 7.

[0026] FIG. 8 is a fragmentary top plan view of a first optical identification according to the present invention.

[0027] FIG. 9 is a fragmentary top plan view of the first optical identification of FIG. 8 with a second identification encoded therein.

[0028] Reference should now be made to the drawing figures, on which similar or identical elements are given consistent identifying numerals throughout the various figures thereof, and on which parenthetical references to figure numbers direct the reader to the view(s) on which the element(s) being described is (are) best seen, although the element(s) may be seen also on other views.

[0029] FIG. 1 illustrates an identification card, generally indicated by the reference numeral 30, which may be assumed to be a bank credit card, or employee identification card, or the like. Card 30 includes a substrate 32 which has disposed thereon a foil strip 34 containing a plurality of diffraction grating elements. Substrate 32 may have disposed thereon a conventional magnetic strip 36 in which information may be magnetically encrypted. Magnetic strip 36 may be separate from foil strip 34, as shown on FIG. 1, or it may have the foil strip superjacent it, such as is described in U.S. Pat. No. 4,631,222, issued Dec. 23, 1986, to Sander, and titled EMBOSSING FOILS, and U.S. Pat. No. 4,684, issued Aug. 4, 1987, to Colgate, and titled SECURITY TAPE WITH INTEGRATED HOLOGRAM AND MAGNETIC STRIP, the disclosures of which patents are incorporated by reference hereinto.

[0030] Foil strip 34 is parallel to and spaced from the upper edge of card 30 and comprises a linear array of diffraction grating elements 40, designated as 40A, 40B, 40C, and 40D, to indicate A, B, C, and D type gratings and, thus, will diffract light in different planes. In the particular embodiment shown, all diffraction grating elements 40 are identical, except that the rotational orientation of each type uniquely differs from the others. Grating elements 40 are arranged so as to form sequential patterns, i.e., D, B, A, D, C, A, B . . . , with, preferably, no two adjacent gratings of the same type. Foil strip 34 can be produced by any conventional technique, such as photographic or embossing techniques used in the art. The sequential patterns can be made highly variable to provide protection against two or more cards 30 with identical strips 34 being issued.

[0031] Additional variability can be introduced when foil strips 34 are introduced during the manufacture of cards 30. In such manufacture of a standard credit card, for example, a foil segment of 3.785 inches in length is used in producing a 3-½-inch card. In producing the sheets from which lengths of segments are cut, with an embossing roll, for example, it is only necessary to ensure that the diameter of the roll is such that the pattern will increment one element 40 at a time through a length of 3.785 inches before repeating. In effect, then, foil strip 34 is placed on substrate 32 in a random manner positionally.

[0032] Referring now to FIG. 2, an optical block 50 is disposed above foil strip 34 so as to sequentially detect grating elements 40 as card 50 is moved relative to the optical block as indicated by the arrow. Optical block 50 includes a light source 52 and a lens 54 arranged to direct light orthogonally onto strip 34 to serially illuminate elements 40. Disposed within optical block 50 are four photodetectors 56-59 arranged so as to receive light diffracted by elements 40A-40D, respectively. Thus, one of photodetectors 56-59 will output a signal as each element 40 passes under optical block 50 and the light is diffracted in one of four optical planes. This is illustrated on FIG. 3, for example, where element 40A is illuminated by light source 52 and that element diffracts light to photodetector 56. Likewise, on FIG. 4

[0033] Providing light source 52 as a 0.3 milliWatt laser diode producing light at 780 nanometers with a 0.007×0.021-inch spot has been found to be satisfactory for detecting diffraction grating elements 40. Other combinations can be employed as well.

[0034] The process of how an identifying number is derived from foil strip 34 (FIG. 1) will be described with reference to FIG. 3. It will be assumed, for illustrative purposes only, that card 30 is a standard bank credit card and that each diffraction grating element is 0.034-inch in width.

[0035] A pattern identification number, “X”, for example, consists of a synchronization number followed by a 16 bit binary number. Information may be encoded in the grating pattern by the grating transition sequence according to the following table, for example:

[0036] AB=1

[0037] AC=1

[0038] BC=1

[0039] BA=0

[0040] CA=0

[0041] CB=0

[0042] The start of each grating number is marked by a unique grating sequence referred to as a “synchronization character”. Synchronization characters are encoded as a “DBAB” sequence. Since only “D” gratings are used in the synchronization character, this unique sequence provides a means for identifying the start of each grating number. The asymmetry of the synchronization pattern allows the direction in which the grating sequence is read to be determined, i.e., “DBAD” versus “DABD”.

[0043] A 16 bit grating number is formed from four six bit digits. A complete grating number consists of 28 grating elements: four synchronization characters followed by 24 gratings (4×6).

[0044] Referring to FIG. 3 and recalling from above that foil strip 34 is placed on card 30 in essentially a random manner with respect to the edge of the card, there will be an offset, “sync offset”, from the edge of the first readable grating element 40 card to the first synchronization character, the sync offset being, in the assumed case, between 0 and 27 grating elements in length. During the reading process, the first readable grating element 40 is detected, the number of grating elements to the first synchronization character is counted, and the first grating number, “X”, is decoded. Then the second grating number “X+1”, is decoded, etc. Depending on the placement of foil strip 34 on card 30, either three or four grating numbers will be present. The card identification number consists of the sync offset plus one or more of the grating numbers. This card identification number can then be encrypted and may be encoded in magnetic strip 36 (FIG. 1) on card 30 and/or stored in a validation computer.

[0045] The use of the first readable grating element 40 is advantageous over, for example, using the edge of card 30 as a reference point. The latter has the disadvantage that, as the card wears, the reference point would be moving. Since a diffraction grating element 40, of the size under consideration, can be read when little as 10 percent of the width of the grating element is present, the use of the first readable grating element as a reference point means that the edge of card 30 can wear at least nine-tenths of a grating element width (plus whatever fraction of a grating element precedes it) before the reference point is changed. To allow for further wear, the validation process permits the sync offset to vary plus or minus one grating element width. This allowance also compensates for the situation, for example, in which an encoding reader is not sensitive enough to read a small sliver of grating element 40, but the validation reader does read the sliver.

[0046] The preferred method for encrypting the card identification number is to encrypt the image data with a user's account or other identification number and with a secret password known only to the issuer of card 30. When card 30 is subsequently presented for authentication, foil strip 34 is read in the manner described above and also the information in magnetic strip 36 is read. The image data and the account number read are then used by a security module to decipher the encrypted information and generate a password. If the calculated password is identical to the user's secret password, the card is presumed to be authentic.

[0047] It is preferable that the grating numbers on a card bear some determinable relationship to one another, such as is indicated on FIG. 5. This permits authentication of card 30 when, say, only the first grating number is used in determining the card number, as above, but one or more gratings in the first grating number have been destroyed and that number cannot be read directly. Knowing the relationship between the first grating number and one or more other grating numbers permits reconstruction of the first grating. Also, it is useful to check all the grating numbers on foil strip 34 so make sure that they are authentic. This requires that a forger forge the entire strip, not just the portion thereof used in generating a card identification number.

[0048] Thus, the secure identification means provides a high degree of variability to minimize the likelihood that two or more duplicate identification means will be produced. This is due to the variability of the diffraction grating pattern in itself, in part because a large number of different such strips may be employed, and having foil strips 34 placed on card 30 in a random manner.

[0049] It is to be noted that the secure identification means is read without the need for a timing signal being provided on the identification means or derived therefrom, no time reference being required for reading the secure identification means, since all data is in encoded in the transitions. Grating elements 40 may be wide or thinner, they can overlap, and/or they can overlap, none of which will affect the operation of the invention. Also, diffraction efficiency is unimportant, since the invention does not measure amplitude, only the presence or absence of a grating element 40.

[0050] To further increase variability, a second encoded identifying number can be placed on foil strip 34. FIG. 6 illustrates foil strip 34 with a bar pattern consisting of a series of bars and spaces superposed thereon. Similar to the construction of the grating pattern on foil strip 34, the bar pattern comprises a series of related numbers, here, “N”, “N+1”, etc. For the embodiment shown, the bar width is always 0.010 inch wide and two different space widths of 0.030 inch and 0.060 inch, “n” and “w”, respectively, are used to create the number pattern, with the narrow element used to represent a “1” and the wide element used to represent a “0”. A third width of 0.150 inch, known as a superwide or “sw” space is used to form synchronization characters. Numbers are developed by combining a sequence of narrow and wide spaces. The start of a number is identified by a synchronization character formed, in this case, as “nswswnn”. This is followed by the two digit hexadecimal representation of the bar number.

[0051] An important aspect of the bar pattern is that, although the pattern has a finite length and, therefore, will repeat after that length, it “walks” with respect to foil strip 34, so that it is randomly placed on the foil strip and also appears randomly on a card 30. Consequently, the bar pattern has its own sync offset from the edge of the card to the first synchronization character. Again, as above with respect to the grating pattern, the sync offset of the bar pattern is combined with one or more of the encoded numbers to produce a second card number which may be encrypted in magnetic strip 36 (FIG. 1). As is illustrated on FIG. 7, the bars are detected by optical block 50 as the absence of any signal from photodetectors 56-59. The pattern of bars is decoded using conventional bar code reading techniques.

[0052] The use of a uniform, known size of grating elements 40 can be used in reading the bar pattern since they can be used to determine the rate of reading which improves discrimination in measuring the widths of spaces between bars and helps negate the effect of scratches. The bar pattern can also be read with reference to the synchronization character of the grating pattern, rather than the first bar read, in order to eliminate any ambiguity in the bar pattern.

[0053] The bars of the bar pattern are shown sloped which is the preferred arrangement when the bars are printed on foil strip 34 by a rotogravure process. The bars may also be orthogonal to the axis of foil strip 34 and may be formed by formed by demetallizing areas of foil strip 34 or by means such as heating or the bars may be formed by other printing techniques. One such technique according to the present invention is to use a thermal transfer printer, such as is used in printing conventional bar codes, to melt the bars into a protective layer placed over foil 34. An advantage of this method is that it can be used to personalize card 30 after it has been manufactured. A large number of unique number sets and offsets can be provided with this method.

[0054] When card 30 (FIG. 1) is being encoded, foil strip will be read by optical head 50 and a microprocessor will receive signals from a signal conditioner representative of the sync offsets for the grating and bar patterns on foil strip 34 and one or more of each of the grating and bar pattern numbers. This information may be encrypted and encoded in magnetic strip 36, as described above, along with other information supplied to the microprocessor, depending on the use of the card, or it may be stored in a validation computer. This other information may include customer identification, account number, etc. The microprocessor may also provide the card identification numbers to a host computer or an external memory.

[0055] When card 30 is presented for authentication, a microprocessor will receive inputs representative of the image on foil strip 34 then being read and will receive image information stored in magnetic strip 36 or in a validation computer memory and the microprocessor will then determine authenticity of the card as described above. If the processing is being done by a host computer, then the image information will be transferred to the host computer to do the comparison with image information stored in the host computer.

[0056] FIG. 8 illustrates a first optical identification, according to the present invention, in the form of a foil strip, and generally indicated by the reference numeral 120. Foil strip 120 is similar to foil strip 34 (FIG. 1) and includes an array of diffraction grating elements 130A, 130B, 130C, and 130D. Similar to foil strip 34, grating elements 130A, 130B, and 130C are arranged to form sequential patterns. Here, and in contrast to foil strip 34, each pair of the latter three grating elements is separated by a grating element of the 130D type. Again, similar to foil 34, transitions between grating elements 130A, 130B, and 130C form a transition sequence which may be used as an identification and read and used as is the case with foil strip 34. The widths of grating elements 130A, 130B, and 130C may be uniform or may vary. Preferably, for reasons which will become apparent below, the 130D gratings are uniform in width.

[0057] FIG. 9 illustrates foil strip 120 in which certain of grating elements 130D have been completely obliterated, as at 140 to form a binary pattern of 130Ds and “not-130Ds” disposed between grating elements 130A, 130B, and 130C. The particular binary pattern in the part of foil strip 120 shown on FIG. 9 could be read as 10101100110. This is similar to the function of bar pattern of FIG. 6; however, the present pattern requires no precision in its formation, as long as the obliteration of the 130D gratings is wide enough to remove all of the selected 130D gratings and to leave at least some of the adjacent grating patterns in place. Preferably, the binary pattern on foil strip 120 is formed by laser etching selected ones of the 130D gratings.

[0058] An advantage of the method of the present invention is that the forming of the two identification codes can be accomplished in two different steps. First, the diffraction grating pattern can be produced and applied to an identification card or other identification substrate. Then, at some later time, the binary pattern can be produced by less than precise means. One hypothetical example of the application of such a process could be the production of a diffraction grating pattern which identifies ABC Manufacturing Company and the resulting identification strips applied to unassigned product labels, the production of the pattern and labels requiring precision manufacturing equipment used by Diffraction Gratings, Inc., the producer of the diffraction grating patterns and labels. Then, Diffraction Gratings, Inc., supplies the product labels with the diffraction grating strips thereon to ABC Manufacturing Company. When ABC Manufacturing Company is ready to apply labels to a product, say, videotapes, ABC uses relatively imprecise equipment to generate the binary code which could identify the product as a videotape and which could also identify the subject of the videotape. The resulting compound secure optical identification can then be used later, for example, for inventory control and/or authentication of the product by reading the manufacturer identification code in the diffraction grating strip and the product identification code in the binary pattern.

[0059] A further advantage of the method of the present invention is that no precision is required in forming obliterated grating elements 140. Since the pattern of grating elements 130A, 130B, and 130C is read by detecting only transitions between grating elements, there does not have to be a clean edge between an obliterated grating 140 and adjacent grating elements—it is only necessary that the D grating be completely eliminated along the reading line and a large portion of the adjacent grating elements can be obliterated as well, as long as enough of the grating elements remain to permit detection of the transitions. Reference to FIG. 9 discloses that the edges of obliterated gratings 140 are irregular and extend well into the adjacent grating elements. Of course, the edges could be straight and precise; however, as noted above, such is not required by the present invention.

[0060] It will thus be seen that the objects set forth above, among those elucidated in, or made apparent from, the preceding description, are efficiently attained and, since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matter contained in the above description or shown on the accompanying drawing figures shall be interpreted as illustrative only and not in a limiting sense.

[0061] It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.