Patent Publication Number: US-9415604-B2

Title: Secure printing using sliced data

Description:
FIELD 
     Embodiments of this disclosure relate generally to systems, apparatus, and methods for printing on security document substrates to create personalized security documents, such as plastic cards and passports. 
     BACKGROUND 
     Many forms of personalized security documents are known including plastic cards that can serve as identification cards, driver&#39;s licenses, financial cards (e.g., credit card, debit card), phone cards, health cards, or the like, as well as security documents such as passports. Personalized security documents often have certain information provided thereon, including but not limited to account numbers, employee numbers, passport numbers, personal information or the like, that can be considered confidential or that it is generally desirable to prevent others from obtaining This information may be printed on a surface of the document often times using a printing process that employs a print ribbon.  FIG. 1  illustrates an example of a personalized security document  1  in the form of a plastic financial card such as a credit card. In this example, the surface of the security document  1  is printed with data such as an account number  2 , card expiration information  3 , the cardholder&#39;s name  4 , and the name of the bank or other financial institution  5 . Other data or material can be printed on the card surface such as a photograph of the cardholder, a logo or other graphics, and the like. 
     When a print ribbon or other ribbon material is used to print/produce information on a plastic card, passport or other personalized security document, certain confidential information, such as account numbers and the like, are left behind on the used ribbon where the dye or ink from the ribbon was transferred to the document. For example,  FIG. 2  illustrates a portion of a used print ribbon  6  that was used to print the data on the card  1  in  FIG. 1 . The used print ribbon  6  contains portions where dye or ink from the ribbon was transferred from the print ribbon to the card  1  leaving behind blank areas (i.e. areas with little or no remaining dye or ink) identical to the data printed on the card  1 . Therefore, someone with even short term access to the used print ribbon  6  can potentially obtain confidential information from the used ribbon  6 , which can then result in unauthorized use of, for example, account numbers and/or creation of counterfeit personalized security documents. U.S. Published Application No. 2013/0032587 describes one technique of minimizing access to information on a used print ribbon that involves destroying the used ribbon after it is used. 
     One known technique for printing data on a card surface involves creating a set of partial data strings by manipulating the original data into the partial data strings. In this technique, the printer would pull the original data apart and create the partial data strings. For example, if the data sent to the printer was “12345”, the following three partial data strings could be created with spaces where the missing data characters would be: “1 3”, “2 5”, and “4”. An image is then created for each partial data string to create partial data string images. Each partial data string image is then individually printed using a separate section of print ribbon, with the card being re-homed prior to each printing pass. The resulting completed printed image is “12345”. This technique works only if the data is printed in a non-proportional font that has equal spaces for all characters. In addition, the partial data strings must include complete characters. This technique breaks apart a series of data characters into partial data strings and then creates an image for each partial data string. This technique does not manipulate an image itself into separate image portions. 
     SUMMARY 
     This disclosure describes techniques that make it difficult for someone to obtain confidential or personal information from one or more used print ribbons after the print ribbon(s) has been used to print information on a surface of a substrate to form a personalized security document. Examples of personalized security documents that can benefit from the techniques described herein include, but are not limited to, plastic cards (or similar cards formed from composite materials) that serve as identification cards, driver&#39;s licenses, financial cards (e.g., credit cards, debit cards), phone cards, health cards, or the like, and documents such as passports. The substrates that can be printed on include, but are not limited to, a plastic card substrate, a transfer material that is printed on and then transferred by lamination onto a plastic card substrate (i.e. retransfer printing), a page of a passport, or the like. 
     In one embodiment, an image to be printed on a surface of a substrate that forms, or will be used in, a personalized security document is generated. The image to be printed is then sliced, divided, separated, etc. into a plurality of separate image portions. Each of the separate image portions is then printed onto the substrate. Together, the separate printed image portions form the desired image on the substrate. However, separately, each image portion contains only a portion of any confidential or personal information. 
     In one embodiment, each separate image portion is printed using separate sections of a single print ribbon. Since each image portion is printed using a different section of the print ribbon, each ribbon section contains only a portion of any confidential or personal information. This makes it difficult for someone to obtain the confidential or personal information from just a brief or casual glance at the used print ribbon since no single section of the print ribbon contains a complete replication of the confidential or personal information. 
     In another embodiment, to further enhance security, each image portion can be printed using a different print ribbon. In this embodiment, one would need long term access to each used print ribbon in order to acquire the confidential or personal information. 
     The confidential or personal information can be any information printed on the resulting card or passport that one wishes to deter others from obtaining from the used ribbon that was used to print the information on the card or passport. Examples of confidential or personal information include, but are not limited to, an account number, a card security code (often called a card verification value (CVV) or card verification code (CVC)), an employee number, passport number, a person&#39;s name, or the like. 
     The techniques described herein can be implemented in any type of plastic card or passport printer where one or more print ribbons are used to print on the substrate. An example of a printer that can be used is desktop printer that has a relatively small footprint intended to permit the desktop printer to reside on a desktop and that is designed to personalize cards or other documents in relatively small volumes, for example measured in tens or low hundreds per hour. An example of a desktop printer is the CD800 Card Printer available from Entrust Datacard Corporation of Shakopee, Minnesota. Another example of a printer is a large volume batch production machine, often configured with multiple processing stations or modules, typically referred to as a central issuance system, that processes multiple documents, such as cards or passports, at the same time and is designed to personalize cards, passports or other documents in relatively large volumes, for example measured in the high hundreds or even thousands per hour. An example of a central issuance system is the MX or MPR-lines of central issuance systems available from Entrust Datacard Corporation of Shakopee, Minnesota. 
     The printer that is implemented with the techniques described herein can have many configurations as long as it uses at least one print ribbon and at least one print head to print on the substrate. For example, the printer can have a single print head and a single print ribbon, multiple print heads with multiple print ribbons, or a single print head with multiple print ribbons. In another embodiment, each image portion could be printed in a different printer. 
     The printing that is implemented by the printer can be any printing type that uses a print ribbon. Examples of printing types include, but are not limited to, dye diffusion, dye sublimation, ink, thermal transfer, pigment, or the like. 
     In one specific embodiment, a process of printing an image on a surface of a card substrate using a printer with a print head and a print ribbon includes generating the image to be printed on the surface of the card substrate. The image itself is then divided into a plurality of separate image portions. Each image portion is then printed on the surface of a card substrate that has been input into the printer. Each image portion is printed using the print head and a separate section of the print ribbon, and the image portions printed on the surface of the card substrate form the image. 
     In yet another specific embodiment, an image is generated that is to be printed on a surface of a security document substrate. The image itself is then divided into a plurality of separate image portions. The image portions can then be transmitted to the security document printer for printing of the image portions. Each image portion can be separately printed on the surface of the security document substrate using a print head and a print ribbon, and each image portion is printed using a new section of the print ribbon. Alternatively, each image portion can be printed using a plurality of print head and print ribbon combinations, and each image portion is printed using a separate one of the print head and print ribbon combinations. 
     In one embodiment, the image portions are created by using masks that mask portions of the image to be printed. One advantage of using masks is that the desired portions of the image can be masked separately and to the desired extent. In addition, in some embodiments, individual characters can be split as opposed to the creation of the partial data strings discussed above where whole characters must be utilized in each partial data string. 
     The printers and methods described herein can be incorporated into self-service systems or kiosks. The self-service systems can include a housing containing a printer adapted to issue a personalized security document and a user interface such as, for example, a touchscreen, keyboard, display screen or combination thereof. The self-service systems can also include communication equipment that facilitates the exchange of information and/or data with a remote computer or server. Optionally, the self-service kiosk can include a camera, scanner, paper printer (for example an ink jet printer) or combinations thereof. An example of a self-service system or kiosk is described in US 2008/0121699 and WO 92/17856 each of which is incorporated herein by reference in its entirety. 
     The printers and methods described herein can also be incorporated into instant issuance systems. An example of an instant issuance system is described in U.S. Pat. No. 8,292,167 that is incorporated herein by reference in its entirety. 
     Other innovative embodiments include a system that includes a plastic card or passport printer having a print head, a print ribbon, a controller and a printer driver. In one embodiment, the image portions are generated in the printer driver and sent to the controller. 
     The resulting used print ribbon is also unique since the used ribbon includes a plurality of sequential, separate image portions formed in the thermally transferrable dye or ink on the substrate web of the ribbon. If viewed separately, the sequential image portions in the used ribbon do not provide sufficient information in a brief or casual glance of the used ribbon to allow one to obtain the confidential or personal information therefrom. However, if the image portions are combined together the resulting combined image would be identical to the image that was printed on the surface of the substrate using the print ribbon. 
    
    
     
       DRAWINGS 
         FIG. 1  illustrates a prior art security document in the form of a card. 
         FIG. 2  illustrates a used section of a ribbon that was used to print the card of  FIG. 1 . 
         FIG. 3  illustrates one embodiment of a method of printing described herein. 
         FIG. 4  illustrates one embodiment of a system described herein for implementing the printing process. 
         FIG. 5  illustrates one embodiment of a printer driver that can be used in the system described herein. 
         FIG. 6  illustrates one embodiment of a printer that can be used to implement the printing method described herein. 
         FIG. 7  illustrates another embodiment of a printer that can be used to implement the printing method described herein. 
         FIG. 8  is a flow chart of another embodiment of a method of printing described herein. 
         FIGS. 9A-C  illustrate a first step in the method of  FIG. 8 . 
         FIGS. 10A-C  illustrate additional steps in the method of  FIG. 8 . 
         FIG. 11  illustrate additional steps in the method of  FIG. 8 . 
         FIG. 12  illustrates one embodiment of a used print ribbon. 
         FIG. 13  illustrates an embodiment of multiple used print ribbons. 
         FIGS. 14A-C  illustrate another embodiment of dividing the generated image into separate image portions using masks and printing image portions. 
         FIG. 15  illustrates a section of print ribbon used to print the image portion of  FIG. 14C . 
         FIGS. 16A-C  illustrate examples of three masks that can be used in a three pass process using the masking technique of the embodiment of  FIGS. 14A-C . 
     
    
    
     DETAILED DESCRIPTION 
     Techniques are described that make it difficult for someone to obtain confidential or personal information from one or more used print ribbons after the print ribbon(s) has been used to print information on a surface of a substrate to form a personalized security document. 
     Examples of personalized security documents that can benefit from the techniques described herein include, but are not limited to, plastic cards (or similar cards formed from composite materials) that serve as identification cards, driver&#39;s licenses, financial cards (e.g., credit card, debit card), phone cards, health cards, or the like, as well as security documents such as passports. 
     The substrates that can be printed on include, but are not limited to, a plastic card substrate, a transfer material that is printed on and then transferred by lamination onto a plastic card substrate in a retransfer printing process, a page of a passport, or the like. 
     For sake of convenience, the security document will hereinafter be described as being a plastic card, and the printing will be primarily described as occurring directly on a plastic card substrate. However, other types of security documents and other types of substrates can be used. 
     For sake of convenience, the printing will hereinafter be described as occurring in a plastic card printer, which can be any type of plastic card printer where one or more print ribbons are used to print on the plastic card substrate. The printer can have a single print head and a single print ribbon, or multiple print heads with multiple print ribbons. In another embodiment, separate plastic card printers could even be used. However, other types of plastic card printers, with other variations of print heads and print ribbons can be used. 
     For sake of convenience, the print ribbon will hereinafter be described as being a dye diffusion print ribbon that includes a substrate web and thermally transferrable dye on the substrate web. However, other types of print ribbons, including ink ribbons, can be used. In general, the print ribbon can contain any colorant material, whether dye, ink or other type of colorant, in a continuous layer or in separate panels, that can be transferred from the print ribbon onto the plastic card or other substrate. 
     For sake of convenience, the print ribbon may hereinafter be described as being a monochromatic dye diffusion print ribbon containing a single continuous dye (i.e. colorant) layer of a single color such as black. However, the print ribbon can be a monochromatic print ribbon containing a plurality of separate dye or ink (i.e. colorant) panels of a single color, or a multi-color print ribbon with separate dye or ink (i.e. colorant) panels of differing colors such as a CMYK print ribbon. 
     With reference to  FIG. 3 , an embodiment of a printing method  10  is illustrated. In the method  10 , an image to be printed is generated in step  12 . The generated image can be an image of the desired layout of all of the text characters and graphics (if present) on the entire front surface of the plastic card substrate. For example,  FIG. 9A  shows an example of a generated image  14  of a desired layout of all of the text characters to be printed on the front surface of the plastic card substrate. In another embodiment, the generated image can be of only a portion of the text characters. For example, again with reference to  FIG. 9A , the generated image could be of only an account number  16  and/or any other information that is considered confidential that one wishes to prevent others from obtaining from the uses print ribbon. The techniques for generating an image to be printed are well-known in the art of plastic card printing and other security document printing. 
     Returning to  FIG. 3 , the generated image is then divided, sliced, separated, etc. into a plurality of separate image portions in step  18 . Each image portion forms only a piece of the generated image to be printed and contains only a portion of any confidential or personal information, such as the account number  16  in  FIG. 9A , that one does not wish to appear in complete form on the used print ribbon. However, if combined, the separate image portions would form the complete generated image from step  12 . 
     The terms divided, sliced, separated, etc. are used interchangeably herein to refer to any division of the generated, to-be printed image into separate pieces with each piece containing only a portion of the text information, such as the account number  16 , that one wishes to prevent access to on the used print ribbon.  FIGS. 8-11  discussed in detail below describe one embodiment of dividing the generated image into separate image portions. 
     Dividing the generated image in step  18  is intended to encompass dividing the image itself as well as dividing the data that forms the image. Whatever language is used, the techniques described herein are intended to encompass any result where separate portions or pieces of the generated image of step  12  result, with the separate portions or pieces then being separately printed onto the card substrate. 
     The resulting number of image portions formed is at least two. In one embodiment, the resulting number of image portions formed is three or more. In another embodiment, the resulting number of image portions is greater than or equal to three but less than or equal to five. 
     Returning to  FIG. 3 , in step  20 , in one embodiment, each of the separate image portions is then printed by the card printer onto the plastic card substrate using different sections of the print ribbon. In another embodiment, the image portions are printed onto the plastic card substrate using separate print ribbons. 
       FIG. 4  is a schematic illustration of an embodiment of a system  30  for implementing the printing method  10  of  FIG. 3 . In the illustrated embodiment, the system  30  includes a card printer  32 , for example a desktop card printer or a central issuance system, that includes at least one print head  34  of known construction, such as a thermal print head with a plurality of resistor elements. A replaceable print ribbon  36  is arrangeable adjacent to the print head  34  so as to be engaged by the print head  34  to transfer dye or ink from the print ribbon  36  onto a surface of the card. The card printer  32  can further include a card input hopper  38  that can hold a plurality of card substrates for feeding into the card printer  32  and a card output hopper  40  that can hold a plurality of card substrates that have been printed on (also referred to as personalized cards). A card transport mechanism  42  of known construction can transport cards through the card printer  32  from the input hopper  38 , past the print head  34  and to the output hopper  40  after printing. Examples of card printers having such a construction are described in U.S. Pat. Nos. 7,434,728 and 6,902,107. 
     In this embodiment, the system  30  can also include a suitable printer driver  44  that generates the image to be printed, divides the image into the image portions, and sends the image portions to the printer  32  using a suitable printer command language. An example of a suitable printer driver is the XPS printer driver as used in the CD800 Desktop Card printer from Entrust Datacard Corporation. The printer driver  44  can be integrated with a controller  46  as illustrated in  FIG. 4  or the printer driver  44  can be separate from the controller  46 . The printer driver  44  and/or the controller  46  can be in well-known wired or wireless communication with the card printer  32 . 
     The card printer  32  can also include a controller  48  included therewith that is in communication with the printer driver  44  and that is configured to receive the image portions and process the image portions to make them ready for printing by the print head  34  as well as control the flow of the card substrate through the printer  32 . 
     The printer driver  44  includes a computer program product with one or more non-transitory computer-readable tangible storage devices, and program instructions stored on at least one of the one or more non-transitory computer-readable tangible storage devices which, when executed, perform the processing necessary to generate the image to be printed, divide the image into the image portions, and transmit the image portions to the printer  32 . 
     The controller  48  includes a computer program product with one or more non-transitory computer-readable tangible storage devices, and program instructions stored on at least one of the one or more non-transitory computer-readable tangible storage devices which, when executed, perform the processing necessary to cause the plastic card printer to print the image portions on the surface of the plastic card substrate to create the desired image. 
     In another embodiment, the controller  46  can generate the image, divide the image into the image portions, and send the image portions to the printer  32 . In this embodiment, the controller  46  would include a computer program product with one or more non-transitory computer-readable tangible storage devices, and program instructions stored on at least one of the one or more non-transitory computer-readable tangible storage devices which, when executed, perform the processing necessary to generate the image, divide the image into the image portions, send the image portions to the printer, and cause the plastic card printer to print the image portions on the surface of the plastic card substrate to create the desired image. 
       FIG. 4  shows the printer driver  44  and the controller  46  as being separate from and outside of the printer  32 . However, in another embodiment, the printer driver  44  and/or the controller  46  can be integrated into and be part of the printer  32  itself. In this embodiment, the controller  46  may also perform the functions of the controller  48 . 
     In an alternative embodiment, some or all of the operations of the card printer  32  can be performed and/or controlled by the remote controller  46  that is external to and remote from the card printer  32 . For example, the controller  46  can perform the data processing functions of the method  10  including generating the image to be printed, dividing the image into the image portions, and sending the image portions to the printer, with the operations of the card printer  32 , such as operation of the print head  34 , the print ribbon  36 , the card transport mechanism  42 , etc., being controlled by the controller  46  and/or by the controller  48 . In one embodiment, the printer driver  44  and/or the controller  46  can be accessible via a website that a user of the card printer  32  logs in to and that performs the data processing functions. 
     With reference to  FIG. 5 , an example construction of the printer driver  44  is illustrated. However, either one of the controllers  46 ,  48  could have a similar construction if the controller  46 ,  48  is intended to perform the functions of the printer driver  44 . 
     In the example illustrated in  FIG. 5 , the printer driver  44  includes a card image generation module  50  that is configured, for example via suitable programming, to generate the image to be printed on the plastic card substrate by the plastic card printer  32 . The card image generation module  50  generates the desired image based on data that is input, for example from a database, from a file, entered in real-time by the user, or the like. The input data can include the cardholder&#39;s name, the account number assigned to the cardholder, card expiration information, and data relating to any other text or graphics to be printed on the card substrate. 
     Once the card image is generated, the generated card image is provided to an image portion generation module  52  that is configured, for example via suitable programming, to generate the plurality of separate image portions from the generated card image. As indicated above, the number of image portions can be two or more, or three or more, or at least three but preferably not more than five. 
     The image portions are then provided to an image portion transmission module  54  that is configured, for example via suitable programming, to transmit each image portion to the printer  32 . Each image portion is then separately printed on the surface of the plastic card substrate by the card printer. 
     The image portions can be sent to the printer  32  and printed in any desired order. For example, the image portions can be sent to the printer in the order they are created and ultimately printed in the same order. For example, in the case of three image portions created in sequence and labeled image portion  1 , image portion  2 , and image portion  3 , the image portions can be transmitted to the printer  32  in the following sequence: image portion  1 , image portion  2 , and image portion  3 ; and ultimately printed in the same sequence. The order of transmission and subsequent printing can also be changed randomly so that when printing one card substrate, the image portions are transmitted and/or printed in a first sequence, and for the next card substrate to be printed the image portions are transmitted and/or printed in a second sequence different from the first sequence. 
     Referring to  FIG. 6 , an example of a print station  60  that can be used in the card printer  32  is illustrated. A card substrate  62  is input via input rollers  64  into printing position between the print head  34  and the print ribbon  36  and a backing roller  66 . Typically, the print head  34  is movable toward and away from the backing roller  66  between a printing position and a card transport position as indicated by the arrow in  FIG. 6 . The print ribbon  36  is supplied from a supply roll  68  with used print ribbon being taken up on a take-up roll  70 . Between the supply roll  68  and the take-up roll  70 , the print ribbon is guided by a plurality of guide posts  72 . 
     In use, the card substrate  62  is fed into position and printing of the first image portion begins. During printing, the card substrate  62  and the print ribbon  36  are fed at substantially the same rate past the print head  34 , with the resistor elements of the print head  34  being suitably activated using conventional techniques to transfer dye or ink from the ribbon  36  to the card substrate  62  at appropriate locations. Once the first image portion is printed, the print head  34  is moved to the transport position, and the card substrate  62  is transported in reverse back to the initial print position. The print head  34  is then moved back to the printing position and the next image portion is printed on the card substrate  62  in appropriate registration with the first printed image portion. For each remaining image portion, this process is repeated. Even though the card substrate  62  is transported back to the initial print position, the print ribbon is not reversed when the card substrate is reversed. Therefore, the second image portion, and each image portion, will be printed using a different section of the print ribbon  36 . 
     Continuing with  FIG. 6 , in an embodiment, one or more additional print stations  80  can be provided downstream from the print station  60 . The print station(s)  80  can have a construction that is identical to the print station  60 . In such an embodiment, rather than reversing the card substrate  62  in order to print second and subsequent image portions, after the first image portion is printed in the print station  60 , the card substrate  62  is transported to the next print station  80  which prints the next image portion in appropriate registration with the first printed image portion. If there are further image portions to be printed, for each additional image portion the card substrate is transported downstream to the next print station to print the next image portion. Therefore, each image portion would be printed using a different print ribbon. 
     With reference to  FIG. 7 , an embodiment of a print mechanism  90  is illustrated where, rather than printing directly on a card substrate, the image portions are printed on a transfer material  92 . Once the entire image is completely printed, the transfer material  92  containing the printed image is transferred to the card surface by a lamination process at a transfer station. This process is generally referred to as re-transfer printing, examples of which are described in U.S. Pat. No. 6,262,755 which is incorporated herein by reference in its entirety and from the SR300 Retransfer Card Printer available from Entrust Datacard Corporation of Shakopee, Minn. 
     In this example, five print stations  94   a - e  are disposed around a drum  96 , with each print station  94   a - e  including a print head and a print ribbon for transferring dye or ink onto the transfer material  92  as the transfer material  92  moves around the drum  96 . The transfer material  92  is provided from a supply roll  98 , and after printing the image on the transfer material  92 , the transfer material  92  is fed to a transfer station  99  to transfer the printed image to the card substrate. The use of five print stations  94   a - e  is optional, and a larger or smaller number of print stations can be used depending upon how many image portions need to be printed. 
     With reference now to  FIGS. 8-11 , an embodiment of dividing the generated image into separate image portions and printing the image portions is illustrated. In this embodiment, the image portions that are created from the generated image are referred to as mask images. 
     First, referring to  FIG. 8 , in this embodiment, a method of printing  100  includes a step  102  of generating the image to be printed onto a card substrate. The step  102  can be similar to the step  12  described above. 
     In step  104 , multiple copies of the image generated in step  102  are created. The number of copies of the image that are created is equal to the number of image portions (or mask images) to be created and printed. For example, as illustrated in  FIGS. 9A-C , three copies  105  of the generated image  14  can be created. However, a larger or smaller number of copies can be created. 
     Returning to  FIG. 8 , in step  106 , each image copy  105  is then overlaid with a mask that hides a predetermined portion of the respective image copy  105  in order to generate a plurality of mask images. Each mask is configured to mask a respective percentage of its associated image copy  105 , based on the number of image copies  105 . For example, in the case of the three image copies  105  in  FIGS. 9A-C , each mask is configured to mask two-thirds of its associated image copy  105 , so that one-third of each image copy  105  remains visible. The masks described herein can be referred to as virtual masks since physical masks are not created. Instead, the masks are created virtually in the data processing that occurs in the image portion generation module  52  in  FIG. 5 . 
       FIGS. 10A-C  illustrate an example of the masking technique in step  106 . In this example, the three image copies  105  are illustrated. For each image copy, a respective mask  108   a ,  108   b ,  108   c  is created such that when the mask  108   a - c  is overlaid over its respective image copy  105 , a portion of each image copy  105  is covered by the mask while the remaining portion of each image copy  105  is not covered. The result is three mask images  110   a ,  110   b ,  110   c . The masks  108   a - c  hide different portions of each image copy  105  such that when the three mask images  110   a - c  are combined, the entire generated image  14  is produced. So in  FIG. 10A , the image copy  105  and the mask  108   a  results in the mask image  110   a  where one-third of the generated image  14  is visible. In  FIG. 10B , the image copy  105  and the mask  108   b  results in the mask image  110   b  where a different one-third of the generated image  14  is visible. In  FIG. 10C , the image copy  105  and the mask  108   c  results in the mask image  110   c  where a different one-third of the generated image  14  is visible. 
     For ease of explanation, the masks  108   a - c  in  FIGS. 10A-C  are illustrated as being a series of solid colored bars  112  alternating with transparent bars  114 . The solid colored bars  112  cover the portions of the image  14  underlying the bars  112  while the portions of the image  14  underlying the transparent bars  114  are not covered. For each of the masks  108   a - c , the sizes, positions, shapes, etc. of the solid bars  112  and the transparent bars  114  can vary to mask the desired areas of the underlying image copies  105 . In one embodiment, the portions of the image  14  underlying the bars  112  form the respective resulting mask images  110   a - c  that are ultimately printed, while the portion of the image not covered by the solid bars  112  are not printed. Alternatively, in another embodiment, the portions of the image  14  not covered by the bars  112  form the resulting mask images  110   a - c  that are ultimately printed, while the portions of the image covered by the solid bars  112  are not printed. The masks  108   a - c  are configured such that no single one of the resulting mask images  110   a - c  completely contains any confidential or personal information that it is desired to prevent access to in the used print ribbon. In the illustrated example, the solid bars  112  and the transparent bars  114  extend vertically relative to the image copies  105 . However, the bars  112 ,  114  can extend horizontally or at any angle between horizontal and vertical. In addition, the masks  108   a - c  are not limited to bars  112 ,  114 . Any pattern, shape, design, sizes, etc. of solid areas and transparent areas can be used that results in creation of the mask images  110   a - c .  FIGS. 14-16  discussed further below describe an alternative example of mask images. Further, although the use of a masking technique has been described, any technique of taking the generated image and creating a plurality of image portions from the generated image that are similar in concept to the mask images  110   a - c  can be used. 
     Returning to  FIG. 8 , in step  116  after a card substrate is input into the card printer, one of the mask images  110   a - c  is printed onto the card substrate using the print head and print ribbon discussed above. For example, with reference to  FIG. 11 , a card substrate  62  is input into the printer. In this example, the card substrate is a blank white card with a first blank, generally planar surface  118  (typically the intended front surface of the card) and a second blank, generally planar surface (not shown) opposite the first surface  118 . In a first print pass, one of the mask images, such as the mask image  110   a , is printed onto the surface  118  of the card substrate  62  to produce a first intermediate printed card  120 . 
     Returning to  FIG. 8 , after the first print pass, in step  122 , the process  100  determines whether there are any remaining mask images to be printed. If the decision at step  122  is no, the process  100  determines that printing is complete  124  and the completed card can be output from the card printer or subject to further card processing. If the decision at step  122  is yes, the process  100  proceeds to step  126  where the card substrate is transported in a reverse direction back to a print position for a second print pass in which a second one of the mask images is printed in step  116 . However, the print ribbon is not reversed in direction. Instead, during the second print pass and each other subsequent print pass, printing on the surface  118  occurs using a new section of the print ribbon. 
     For example, with reference to  FIG. 11 , the first intermediate printed card  120  is transported in the reverse direction back past the print head and positioned for the second print pass. Once in position, the first intermediate printed card  120  is transported past the print head in the second print pass using a new section of print ribbon to print a second one of the mask images, such as the mask image  110   b , onto the surface  118  to produce a second intermediate printed card  128 . 
     Returning to  FIG. 8 , if step  122  again determines that there are remaining mask images to be printed the process  100  proceeds to step  126  and back to step  116  for another print pass. For example, with reference to  FIG. 11 , the second intermediate printed card  128  is transported in the reverse direction back past the print head and positioned for a third print pass. Once in position, the second intermediate printed card  128  is transported past the print head in a third print pass to print a third one of the mask images, such as the mask image  110   c , onto the surface  118  using yet another new section of print ribbon to produce the final printed card  130  containing the generated image  14 . 
     During each print pass and return of the card substrate back for each new print pass, the positioning of the card substrate is such that once printing is complete, the mask images  110   a - c  substantially align with one another such that they form the desired generated image which can be seen by comparing the images  14  in  FIGS. 9A-C  with the final printed card  130  in  FIG. 11 . 
     Although the mask images are described as being printed in the sequence  110   a → 110   b → 110   c , any print sequence can be used. In addition, the print sequence of the mask images can vary for each card substrate being printed. 
       FIG. 12  illustrates an example of the print ribbon  36  after printing of the mask images  110   a - c . In this example, the print ribbon  36  contains a continuous layer of thermally transferrable dye or ink  134 , such as black dye or ink, disposed on a substrate web  136 . The used print ribbon  36  includes a plurality of sequential, separate image portions formed in the thermally transferrable dye or ink on the substrate web each of which corresponds to one of the mask images  110   a - c . If the image portions on the print ribbon are combined together, the resulting combined image would be identical to the image  14  printed on the surface of the final printed card  130 . 
     For example, the print ribbon  36  includes one portion  132   a  that was used to print one of the mask images, a second portion  132   b  that was used to print a second one of the mask images, and a third portion  132   c  that was used to print a third one of the mask images. In this example, the portion  132   a  was used to print the mask portion  110   b , the portion  132   b  was used to print the mask portion  110   a , and the portion  132   c  was used to print the mask portion  110   c . Therefore, the mask images were printed in the sequence  110   b → 110   a → 110   c.    
       FIG. 13  illustrates an embodiment where, instead of using a single print ribbon to print each mask image, separate print ribbons  36   a ,  36   b    36   c  are used to print each mask image. For example, the print ribbon  36   a  was used to print the mask image  110   b , the print ribbon  36   b  was used to print the mask image  110   a , and the print ribbon  36   c  was used to print the mask image  110   c.    
     The print ribbons illustrated in  FIGS. 12 and 13  are examples only. Many variations can exist. The print ribbon used can have individual panels of dye or ink, for example like in a CYMK print ribbon, with each panel being used to print one of the mask images. The ribbon portions  132   a - c  need not be arranged one after the other as illustrated in  FIG. 12 . Instead, the ribbon  36  can be advanced a distance after each printing pass so that there is a gap between each ribbon portion  132   a - c . However, the ribbon portions  132   a - c  would still be considered sequential. It is also possible to advance and reverse the print ribbon after certain print passes such that the print portions  132   a - c  used to print one card are intermingled with the print portions  132   a - c  used to print another card. Any variations that results in the mask images being printed on separate portions or sections of print ribbon can be utilized. 
       FIGS. 14-16  another embodiment of dividing the generated image itself into separate image portions using masks and printing image portions. In this embodiment, entire data characters are printed during each printing pass wherever possible. For example, an entire letter “A” or an entire number “1” is printed whenever possible. This is in contrast with the embodiment described above in  FIGS. 10-11  where the masking can result in an individual character being partially printed during a single printing pass, with multiple printing passes being needed to result in the entire individual character being printed. 
       FIG. 14A  illustrates an image  150  of a card that is to be printed. Similar to the embodiment described in  FIGS. 10A-C  above, two or more, for example three to five, of the images  150  can be generated. For each image copy  150 , a respective mask image  152  is created. In this embodiment, each mask image  152  can include a plurality of solid color bars  154 . When the mask image  152  is overlaid over its respective image copy  150 , certain ones of the bars  154  overlay certain ones of the data characters on the image copy  150 . Any data character that lies below one of the mask bars  154  will be printed. For example, when the mask image  152  is overlaid over the image  150 , the individual characters “3”, “1”, “8”, “/”, “P” and “T” are covered by the bars  154 . Therefore, as shown in  FIG. 14C , a first intermediate printed card  156  resulting from a single printing pass will result in the individual characters “3”, “1”, “8”, “/”, “P” and “T” being printed in their entireties on the card  156 . The first intermediate printed card  156  would then be repositioned for a second printing pass using a second differently configured mask with bars  154  that overlay other data characters which will then be printed. This process is repeated until the entire intended card image  150  is printed on the card. 
     As with the embodiments described above, a new section of ribbon, or a different print ribbon, will be used in each printing pass to print the data characters for that printing pass.  FIG. 15  illustrates a section of print ribbon  158  that was used to print the data characters in  FIG. 14C . 
       FIGS. 16A-C  illustrate examples of three mask images that can be used in a three pass printing process using the masking technique of the embodiment of  FIGS. 14A-C .  FIG. 16A  illustrates a mask image  160   a  that can be used to print elements on the card other than the data characters, such as background printing, printing of a logo, and the like, during a first printing pass. The solid colored areas cover areas of the card surface other than where the data characters are located, so that those areas are printed. If desired, the mask image  160   a  can be configured to overlay some of the data characters so that those data characters are also printed during the first printing pass.  FIG. 16B  illustrates a mask image  160   b  that can be used to print certain ones of the data characters (i.e. the data characters overlaid by the bars  154 ) onto the card during a second printing pass.  FIG. 16C  illustrates a mask image  160   c  that can be used to print the remaining ones of the data characters (i.e. the data characters overlaid by bars  154 ) onto the card during a third printing pass. Similar techniques can be used where four mask images and four printing passes, five mask images and five printing passes, and the like, are employed. 
     The following additional inventive aspects from the preceding disclosure can be summarized as follows: 
     In aspect 1, a system includes a plastic card printer having a print head, and a print ribbon; a printer driver in communication with the plastic card printer; a controller in communication with the plastic card printer and the printer driver; either the printer driver or the controller includes a) a card image generator that generates an image to be printed on a surface of a plastic card substrate, b) an image portion generator that generates a plurality of separate image portions from the generated image to be printed, and c) an image portion transmitter that transmits each image portion to separately print each image portion on the surface of the plastic card substrate using a different section of the print ribbon. 
     Aspect 2 is the system of aspect 1, wherein the image portion generator has a plurality of mask images, and each separate image portion is associated with a respective one of the mask images. 
     Aspect 3 is the system of aspect 2, wherein each mask image includes a plurality of bars that overlay select portions of the image to be printed. 
     Aspect 4 is the system of aspect 3, wherein each image portion comprises portions of the image to be printed that are overlaid by the bars on the respective mask image. 
     In aspect 5, a plastic card printer driver comprises an image generation module that is configured to generate an image to be printed on a surface of a plastic card substrate by a plastic card printer; an image portion generation module that is configured to generate a plurality of separate image portions from the generated image; and an image portion transmission module that is configured to transmit each image portion to the plastic card printer to separately print each image portion on the surface of the plastic card substrate. 
     In aspect 6, a computer program product is provided that works with a plastic card printer and that includes one or more non-transitory computer-readable tangible storage devices, and program instructions stored on at least one of the one or more non-transitory computer-readable tangible storage devices which, when executed, perform the following to cause the plastic card printer to print an image on a surface of a plastic card substrate: 
     generating an image to be printed on the surface of the plastic card substrate by the plastic card printer; 
     generating a plurality of separate image portions from the generated image; and 
     transmitting each image portion to the plastic card printer to cause each image portion to be separately printed on the surface of the plastic card substrate, with the image portions that are printed on the surface of the security document substrate form the image. 
     Aspect 7 is the computer program product of aspect 6 wherein the plurality of separate image portions are generated using a plurality of mask images, and each separate image portion is associated with a respective one of the mask images. 
     Aspect 8 is the computer program product of aspect 7, wherein each mask image includes a plurality of bars that overlay select portions of the image to be printed. 
     Aspect 9 is the computer program product of aspect 8, wherein each image portion comprises portions of the image to be printed that are overlaid by the bars on the respective mask image. 
     The examples disclosed in this application are to be considered in all respects as illustrative and not limitative. The scope of the invention is indicated by the appended claims rather than by the foregoing description; and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.