Abstract:
An identification document having enhanced security and replication deterrence, while providing a simple low cost solution to other verification and authentication technologies. In one implementation, the document is provided with a multi-layer, multi-axis diffractive optical variable image device (DOVID) that is based on specific data or information on the document. The result is that the DOVID is directly tied to data or information that is specific to the document. This DOVID security feature is verifiable by the human eye so that no high levels of technology are necessary to verify authenticity. In addition, this DOVID security feature has enhanced tamper detection.

Description:
TECHNICAL FIELD 
   The invention relates to identification documents and the production thereof, as well as to the use of diffractive optically variable image device (DOVID) technology in the production of identification documents. 
   BACKGROUND 
   Diffractive optically variable image devices (hereinafter DOVIDs) are diffractive images based on optical interference techniques. One class of DOVID is a hologram where multiple perspective dimensionality is preserved. In layman&#39;s nomenclature, the word “hologram” is commonly substituted as a generic term for DOVIDs. Another form of DOVID is grating imagery where only a single perspective dimensionality is preserved. 
   DOVIDs have been in used in many applications to protect replication sensitive documents. Some of the first uses of DOVIDs involved the protection of credit cards. Since then, several types of diffractive imaging technology have been developed to increase the difficulty of producing counterfeit documents. 
   All DOVIDs present a reflected image which changes appearance when tilted slightly at various angles. This unique characteristic makes a DOVID image impossible to copy or imitate by conventional printing and computer based graphical hardware and software processes. 
   Current DOVID technology used to protect replication sensitive documents, for example identification documents such as credit cards, relies on generic DOVIDs that have no ties to the actual information that is present on the documents. Further, DOVID material that is currently in use is becoming increasingly available on the gray market in which the DOVID material is initially legally obtained but later sold or distributed illegally or under questionable circumstances. As a result, conventional generic DOVIDs are becoming far from secure. 
   What is needed is an enhanced security document, for example an identification document such as a passport, driver&#39;s license, credit card, identification card, and the like, that more effectively utilizes DOVID technology, as well as improved methods relating to the production of such documents. 
   SUMMARY 
   The invention provides an improved identification document, and improved methods of making an identification document, having enhanced security and replication deterrence, while providing a simple low cost solution to other verification and authentication technologies. 
   The invention utilizes a security feature in the form of DOVID technology that, in one embodiment, is integrated with specific data or information on the document to be secured. The result is that the security feature is directly tied to data or information that is specific to the document. The security feature is verifiable by the human eye so that no high levels of technology are necessary to verify authenticity. In addition, the security feature has enhanced tamper detection. 
   The concepts of the invention could be used on any document in which security (e.g. tamper detection, verification, authentication) of the document is a concern and unauthorized replication of the document is undesirable. Examples of documents that could benefit from the concepts of the invention include cards such as identification cards, driver&#39;s licenses, credit cards and the like, as well as passports. 
   In one embodiment of the invention, a document is formed with a multi-layer DOVID that has multiple axes of diffraction. The number of DOVID layers can vary depending upon the security requirements, although it is preferred that there be at least two DOVID layers. The DOVID can be formed over an image or text that is on the document, with the DOVID formed in precise registration with the image or text. The DOVID is specific to, and based on, the image or text that it is formed over. As a result, the DOVID is unique to the document that it is formed on thereby reducing the potential for counterfeiting and enhancing the ease of verifying document integrity. 
   In a first aspect of the invention, an identification document comprises a document surface having information relating to the intended holder of the identification document provided thereon, and a diffractive optically variable image device is on the document surface, where the image device is based on at least a portion of the information on the document surface. 
   In another aspect of the invention, an identification document comprises a document surface having information relating to the intended holder of the identification document provided thereon, and a multi-layer diffractive optically variable image device on the document surface, where the diffractive optically variable image device has multiple axes of diffraction and is formed on the document surface. 
   In still another aspect of the invention, an identification document comprises a document surface having information provided thereon, and a diffractive optically variable image device on the document surface, where the diffractive optically variable image device is created after the information is formed on the identification document and is based on at least a portion of the information. 
   In still another aspect of the invention, a method of producing an identification document comprises providing an identification document having a document surface with information, including information relating to the intended document holder, formed thereon, and forming a diffractive optically variable image device on the document surface that is at least in part based on at least a portion of the information. 
   For a better understanding of the concepts of the invention, the advantages and objects obtained thereby, reference should be made to the drawings which form a further part hereof, and to the accompanying description, in which there is described a preferred embodiment of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  illustrates a card format suitable for employing the DOVID technology according to the invention. 
       FIG. 2  is an example of an image that can be printed on a card. 
       FIGS. 3A-C  illustrate images of pixel segments that are created from the image in  FIG. 2 . 
       FIGS. 4A-D  are images illustrating a bi-level segmentation process. 
       FIG. 5  illustrates a card with an offset DOVID according to the invention. 
       FIG. 6  is a flowchart of steps in the method of creating a secure card. 
   

   DETAILED DESCRIPTION 
   An identification document capable of utilizing the concepts of the invention is illustrated in  FIG. 1 . The document is illustrated as a card  10  which could be, for example, an identification card, a driver&#39;s license, a credit card or the like. Although the inventive concepts will be described herein in relation to the document being a card, it to be realized that the inventive concepts could be utilized on any document, for example a passport, in which security (e.g. tamper detection, verification, authentication) of the document is a concern and unauthorized replication of the document is undesirable. 
   The card  10  has a card surface  12  upon which is located a variety of information, including information relating to the intended holder of the identification document, including one or more of a photographic image  14  and text  16 , and information unrelated to the intended holder of the identification document, for example a logo image  18 . The image  14  is typically of the intended card holder, while the text  16  can include, for example, information on the intended card holder such as the card holder&#39;s name and address, information relating to the card issuer such as the employer, or the card number. The logo image  18  can be of the type often found on cards, for example a corporate logo, a logo of the entity that issued the card, etc. The card  10  can include various combinations of one or more of the image  14 , text  16  and logo image  18 , as well as other data. The card  10  can also include other types of information relating to the intended card holder, either in addition to, or separate from, one or more of the above types of information, for example one or more fingerprints of the card holder and random information that uniquely identifies the card holder. 
   The image  14 , text  16  and logo image  18  can be printed onto the card surface  12  using suitable card printing technology, such as dye sublimation. The image  14  and logo image  18  are often multi-color images that result from Yellow-Magenta-Cyan (YMC) dye sublimation printing, while the text  16  is typically black also resulting from dye sublimation printing. Equipment for performing multi-color and monochromatic dye sublimation printing on card surfaces is available from DataCard Corporation of Minnetonka, Minn. 
   The concepts of the invention will be further described in relation to the image  14  that is YMC printed onto the card surface  12 . However, the inventive concepts described herein could also be applied to the text  16  and logo image  18  as well. 
   As described in more detail below, the invention provides a DOVID security feature that is dictated by and unique to the image  14 . In one embodiment, the security feature is formed over the image  14  in registration therewith. The DOVID security feature is preferably a multi-layer, multi-axis of diffraction feature that is formed over the image  14 . Each layer of the DOVID security feature comprises a layer of DOVID material in the form of a diffraction grating printed onto the image  14 . The result is that when the image  14  is viewed from different orientations, the image  14  that is seen by the naked eye changes appearance. 
   The image  14  over which the DOVID security feature is formed is a white light image defined as an image that is visible in ordinary white light and which does not change color with changes in orientation. 
   Turning now to  FIG. 2 , an example of a dye sublimation printed photographic image  14  is shown. It is to be understood that the image  14  is actually a YMC, multi-color image, although the various colors are not apparent from  FIG. 2 . 
   To produce the DOVID security feature, a segmentation process is performed on the image  14  in  FIG. 2 , in which the image  14  is segmented into a predetermined number of segments based on pixel intensities. Each segment covers a range of pixel intensities. For example, one segment could comprise pixel intensities from 0-84, a second segment could comprise pixel intensities from 85-169, and a third segment could comprise pixel intensities from 170-255. To perform segmentation, the data used to print the image  14  is processed and the data representing the various pixels of the image  14  are placed into the appropriate segment based on the resulting pixel intensity to form separate data sets. Segmentation can be performed by a single point process of examining each resulting pixel in a progressive x, y coordinate system, or by the use of a look-up table. 
   For example, if the number of desired segments is three, the data set of segment  1  would contain the data resulting in pixels whose intensities fall within the intensity range assigned to segment  1 , for example 0-84. Likewise, the data set of segment  2  would contain the data resulting in pixels whose intensities fall within the intensity range assigned to segment  2 , for example 85-169, while the data set of segment  3  would contain the data resulting in pixels whose intensities fall within the intensity range assigned to segment  3 , for example 170-255. 
     FIGS. 3A-C  are print-outs of data sets of an exemplary segmentation process on the image in  FIG. 2 .  FIG. 3A  shows a print out  20  of the data set of the lower one-third of the pixel values which can be designated as segment  1 .  FIG. 3B  shows a print out  22  of the data set of the middle one-third of pixel values which can be designated as segment  2 .  FIG. 3C  shows a print out  24  of the data set of the upper one-third of pixel values which can be designated as segment  3 . Although the segmentation has been described as being in equal segments (⅓, ⅓, ⅓), it is to be realized that the segmentation need not be equal, for example by using a technique such as histogram analysis. 
   Once segmentation is complete, the DOVID security feature is produced by printing a DOVID material layer in the form of a diffraction grating for each segment. The grating of each DOVID layer is arranged at a different angle from the other DOVID layers. A material suitable for use in forming the DOVID grating layers is disclosed in U.S. patent application Ser. No. 10/605,139, and is produced by ITW Holopak of East Brunswick, N.J. 
   With reference to  FIG. 6 , to begin creating the DOVID security feature, the image  14  is initially printed onto the card surface  12  at step  30 . Next, at step  32 , the data used to print the image  14  is processed. Segments having selected ranges of pixel intensity values are chosen at step  34 , and the image data is then segmented at step  36  by assigning the pixels that result from the image data to the appropriate segment to create data sets. 
   Once the image data has been segmented, the multi-layer, multi axis DOVID can then be formed over the image. To aid in describing the invention, assume that the print-out  20 /segment  1  in  FIG. 3A  is used to produce a first DOVID layer with a diffraction grating at a first angle, print-out  22 /segment  2  in  FIG. 3B  is used to produce a second DOVID layer with a diffraction grating at a second angle, and print-out  24 /segment  3  in  FIG. 3C  is used to produce a third DOVID layer with a diffraction grating at a third angle. 
   To form the first DOVID layer, the data from segment  1  is sent to the printer to print DOVID material as a diffraction grating at a first grating angle onto the image  14  in registration with the image. The resulting first DOVID layer replicates the image shown in  FIG. 3A . The second DOVID layer is formed over the first DOVID layer by sending the data from segment  2  to the printer to print DOVID material as a diffraction grating at a second grating angle onto the first DOVID layer and over the image  14  in registration with the image. The resulting second DOVID layer replicates the image shown in  FIG. 3B . The third DOVID layer is formed over the second DOVID layer by sending the data from segment  3  to the printer to print DOVID material as a diffraction grating at a third grating angle onto the second DOVID layer and over the image  14  in registration with the image. The resulting third DOVID layer replicates the image shown in  FIG. 3C . 
   The result is a card that has the normal image  14 , with the addition of a real time created, three-axis DOVID image that replicates the image  14  and is formed in registration therewith, but with the characteristics of the DOVID. Each DOVID layer is formed by a diffraction grating having an axis different than the grating axis of the other DOVID layers so the DOVID layers do not nullify each other. Therefore, the images shown in  FIGS. 3A-C  are formed over the image  14  and are visible when the orientation of the card is changed. The DOVID is not a generic, pre-formed device that is applied to many cards as is conventionally done. Instead, the DOVID is created specifically for each card and is based at least in part on at least a portion of the information on the card. The DOVID can thus be referred to as being “card specific” or more generically “document specific”. A DOVID that is based on the information on the card surface means that the DOVID is formed by using the printed information or is formed by using the data that is used to produce the printed information. 
   Although the use of three segments and resulting three DOVID layers has been described, the DOVID security technology of the invention could be implemented using two or more DOVID layers. Further, a single layer could be formed over the image  14  if a simple holographic effect is desired. 
   In order to protect the DOVID and the information on the card, a protective overlay can be applied over the card surface  12  after the DOVID is formed. 
   The above described example discussed segmentation of the multi-color image  14 . However, segmentation can also be used on a black and white image (or other information on the card) in order to produce a DOVID security feature based on the black and white image. An example of segmentation of a black and white image to produce a DOVID security feature according to the concepts of the invention will now be discussed with reference to  FIGS. 4A-D . For this explanation, it is to be assumed that the image to be segmented is a black and white image, rather than a multi-color, YMC image. 
   Initially, an edge detection algorithm such as a Laplacian, Sobel, Prewitt, etc. processes the original raster image. This creates the image data as shown in  FIG. 4A . The original raster image is also subjected to a threshold process to create an appropriate black and white image. All of the white pixels are assigned to one segment that will be used to create one DOVID layer. All the black pixels are assigned to a second segment that will be used to create the second DOVID layer. The pixel information from the edge detection process ( FIG. 4A ) is assigned to a third segment that will be used to create the third DOVID layer. To insure that the DOVID maintains the greatest amount of perception information, the edge data ( FIG. 4A ) is subtracted from the black image data resulting in the image information contained in  FIG. 4B . In addition, the image data comprising the white threshold data is inverted to make a negative image. The edge information ( FIG. 4A ) is then subtracted from the inverted white image data resulting in the image information contained in  FIG. 4C . 
   To further describe this process, assume the black pixels are assigned a value of one and the white pixels are assigned a value of zero. When the image in  FIG. 4A  is subtracted from the threshold black image data, any corresponding pixels in that data that are also black in  FIG. 4A  will be turned white (i.e. 1-1). If the corresponding pixels in the image were white, then subtracting the black pixels would result in a negative value (0-1). Only positive value pixels would be printed and represented in the illustrated images as black. 
   In  FIGS. 4A-C , if a pixel is black it will be printed on the document either as part of the white light image or as part of the multiple DOVID layers.  FIG. 4D  illustrates the image that would be printed by the K or black panel of the print ribbon and that the images in  FIGS. 4A-C  would be formed over. The image constitutes the pixels of the white light image and is created by accepted dithering practices.  FIGS. 4A-4C  each form one layer of the DOVID, with each layer having a different diffraction grating axis as discussed above. 
   The DOVID security features described herein could be produced over any other information on the card  10 . Further, the DOVID layers could be offset from the information or a combination of offset and registered.  FIG. 5  illustrates a DOVID  50  that is created as discussed above for  FIGS. 3A-C , but which is offset from the image  14 . 
   Additional implementations of the DOVID security technology described herein are illustrated in  FIG. 1 . In one, a DOVID that is based at least in part on at least a portion of the text  16  is produced in multiple lines  40  across the surface  12  of the card  10 . In the implementation shown in  FIG. 1 , each line  40  extends substantially the entire length of the card, and the lines are spaced from one another along substantially the entire height of the card, although other configurations are possible. The text upon which the DOVID is based could be, for example, the card holders name. In one version, the card holders entire name could be reproduced as a DOVID, in which the name repeats in each line  40 , and forms the background to the card. 
   In another implementation, a DOVID that is based at least in part on at least a portion of the logo image  18  is produced in multiple lines  42  across the surface  12  of the card  10 . In the implementation shown in  FIG. 1 , each line  42  extends substantially the entire length of the card, and the lines are spaced from one another along substantially the entire height of the card, although other configurations are possible. In one version, the entire logo image could be reproduced as a DOVID, in which the DOVID logo repeats in each line  42 , and forms the background to the card. 
   The technology and concepts described herein can be further enhanced by utilizing microprinting on the last (or uppermost) layer of the DOVID. 
   The above specification, examples and data provide a complete description of the manufacture and use of the inventive technology and concepts. Since many embodiments of the inventive technology and concepts can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.