Patent Publication Number: US-6663945-B2

Title: Multilayer card

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to multilayer cards, and more specifically, to multilayer cards and methods of manufacturing the multilayer cards. 
     Various identification cards have been used for identifying individuals. Those identification cards have some security marks or prints in order to avoid counterfeiting. Furthermore, identification cards usually have to be protected against tampering on the surfaces of the cards. For example, some cards are covered by a transparent plastic film for surface protection. 
     In the prior art, a printer such as a thermal transfer printer prints images on a base material of such an identification card first. Then, the process of covering the card by a film is performed after printing. Therefore, the prior art requires two separate steps for making laminated tamper-proof cards: a printing step and a laminating step. However, this two-step manufacturing technique poses some problems. Since the printing step and the laminating step are performed by totally different mechanisms, it is difficult to easily incorporating two functions into a single machine. As a result, providing a printer which outputs tamper-proof, printed cards becomes economically unrealistic especially for personal use. 
     In view of these and other issues, it would be desirable to have a technique allowing a thermal transfer printer to print an identification card and then apply a tamper-proof layer on the card. 
     SUMMARY OF THE INVENTION 
     According to various embodiments of the present invention, a multilayer card has a base layer, a watermark layer, an image layer, and an opaque layer. The watermark layer is provided on the base layer, and is at least partially transparent. The image layer is provided on the watermark layer. The opaque layer is provided on the image layer. The opaque layer functions as a protective layer against tampering or scratching. 
     In some embodiments, the opaque layer includes a metallic layer. 
     In some specific embodiments, the opaque layer includes a regular color layer. 
     A further understanding of the nature and advantages of the present invention may be realized by reference to the remaining portions of the specification and the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The invention, together with further objects and advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying drawings in which: 
     FIG. 1 is a cross-sectional view of a thermal transfer printer for manufacturing a specific embodiment of a multilayer card according to the present invention. 
     FIG. 2 is a cross-sectional view of an alternative thermal transfer printer for manufacturing the multilayer card according to the present invention. 
     FIG. 3 is a cross-sectional view of a specific example of the ink film used for the embodiments of the multilayer card and the method of manufacturing the multilayer card according to the present invention described referring to FIGS. 1 and 2. 
     FIG. 4 is a cross-sectional view of a multilayer card of a specific embodiment according to the present invention during the printing process. 
     FIG. 5 is a cross-sectional view of the multilayer card of a specific embodiment according to the present invention after the printing process. 
     FIG. 6 is a cross-sectional view of a multilayer card of an alternative embodiment according to the present invention. 
     FIG. 7 is a cross-sectional view of a multilayer card of another specific embodiment according to the present invention. 
     FIG. 8 is a cross-sectional view of a specific example of the base layer film used for the embodiments of the multilayer card and the method of manufacturing the multilayer card according to the present invention described referring to FIGS.  1  and  2 . 
    
    
     DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS 
     Various embodiments of the present invention will now be described in detail with reference to the drawings, wherein like elements are referred to with like reference labels throughout. 
     Various embodiments of the present invention have a base layer, a watermark layer, an image layer, and an opaque layer. The opaque layer functions as a protective layer against tampering or scratching. 
     FIG. 1 is a cross-sectional view of a thermal transfer printer  100  for manufacturing a specific embodiment of a multilayer card according to the present invention. The thermal transfer printer  100  includes a roller printing section  102 , a thermal transfer printing section  104 , and a controller  106  within a housing  108 . A printing medium  110  is fed along a medium flow path  112  from left to right in FIG.  1 . FIG. 1 shows three locations of the printing medium  110  in the thermal transfer printer  100 . 
     Suitable polymers for the printing medium  110  include polyvinylchloride (PVC), polycarbonate (PC), acrylonitrile-butadiene-styrene (ABS), polypropylene sulfate (PPS), and polyethylene terephthalate glycol (PETG). Circles shown in FIG. 1 represent rollers or platens, and elongated rectangulars  110  in FIG. 1 represent cards or plate-like materials used as the printing medium  110 . 
     The roller printing section  102  includes a transfer roller  120  which is operable to heat opaque ink on an ink film  122 , thereby transferring the opaque ink from the ink film  122  to the printing medium  110 . In order to heat the opaque ink, the transfer roller  120  has a heater  124  therein. In order to apply pressure to the ink film  122  and the printing medium  110 , the transfer roller  120  is mechanically coupled to a pressure mechanism  126  which presses the transfer roller  120  against a platen  128 . The pressure mechanism  126  includes, for example, a spring. Thus, the transfer roller  120  presses the ink film  122  and the printing medium  110  against the platen  128 . The ink film  122  includes at least one of a gold color layer, a silver color layer, and a bronze color layer on a base film. The base film is made from plastic materials including polyethylene terephthalate (PET). 
     The platen  128  included in the roller printing section  102  in this specific embodiment is a roller having a rubber layer thereon. However, the platen  128  may be any other suitable type of platen including a flat platen. Feeding rollers  130  and  132  feed the printing medium  110  onto the transfer roller  120  and the platen  128  along the medium flow path  112 . The controller  106  controls rotational speeds and directions of the transfer roller  120  and the feeding roller  130  appropriately. 
     The thermal transfer printing section  104  is operable to heat regular color ink on a regular color ink film  140  for transfer the regular color ink from the regular color ink film  140  to the printing medium  110 . The regular color ink film  140  includes at least one of a cyan color layer, a magenta color layer, a yellow color layer, a black color layer, and a white color layer on a base film. The base film is made from plastic materials including polyethylene terephthalate (PET). 
     The thermal transfer printing section  104  includes a printing head  142  having a plurality of resistance heating elements  144 , and a platen  146 . The resistance heating elements  144  apply heat to the regular color ink film  140  based on electric drive pulses representing image data. The printing head  142  presses the regular color ink film  140  and an intermediate transfer film  148  against the platen  146 , thereby transferring the regular color ink to the intermediate transfer film  148  by heat and pressure. The intermediate transfer film  148  constitutes a closed loop, which rotates counterclockwise in FIG. 1 supported by feeding rollers  150 ,  152 ,  154  and  156 . 
     The regular color ink transferred from the regular color ink film  140  to the intermediate transfer film  148  is carried counter clockwise to a point where an intermediate transfer roller  158  and a platen  160  contact the printing medium  110 . In order to determine the exact position of the printing medium  110 , the thermal transfer printing section  104  includes a sensor  162  which detects a predetermined point on the printing medium  110  by utilizing, for example, an optical sensing technique. Feeding rollers  164  and  166  feed the printing medium  110  onto the intermediate transfer roller  158  and the platen  160  along the medium flow path  112 . The controller  106  controls rotational speeds and directions of the feeding roller  164  appropriately. 
     The printing medium  110  is positioned on a predetermined point on the medium flow path  112  by using the sensor  162  and the feeding roller  164  controlled by the controller  106 . Then, the feeding rollers  164  and  166  feed the printing medium  110  onto the intermediate transfer roller  158  and the platen  160  along the medium flow path  112 . The intermediate transfer roller  158  presses the intermediate transfer film  148  and the printing medium  110  against the platen  160 , thereby transferring the regular color ink from the intermediate transfer film  148  to the printing medium  110  by pressure. Feeding rollers  170  and  172  feed the printing medium  110  out of the housing  108  of the thermal transfer printer  100  along the medium flow path  112 . The controller  106  controls rotational speeds and directions of the feeding rollers  170  and  172  appropriately. 
     FIG. 2 is a cross-sectional view of an alternative thermal transfer printer  200  for manufacturing the multilayer card according to the present invention. The thermal transfer printer  200  includes the roller printing section  102 , a thermal transfer printing section  204 , and the controller  106  within the housing  108 . The differences between the embodiments shown in FIGS. 1 and 2 mainly reside in the thermal transfer printing section  204 . Thus, it should be appreciated that elements in FIG. 2 which are assigned the same reference labels as shown in FIG. 1 have the same functionalities as those of FIG. 1 with the exception that the elements are designed to be coordinated with the thermal transfer printing section  204 . 
     The thermal transfer printing section  204  is operable to heat regular color ink on a regular color ink film  240  for transfer the regular color ink from the regular color ink film  240  to the printing medium  110 . The regular color ink film  240  includes at least one of a cyan color layer, a magenta color layer, a yellow color layer, a black color layer, and a white color layer on a base film, which is made from plastic materials including PET. 
     The thermal transfer printing section  204  includes a printing head  242  having a plurality of resistance heating elements  244 , and a platen  246 . The resistance heating elements  244  apply heat to the regular color ink film  240  based on electric drive pulses representing image data. The printing head  242  presses the regular color ink film  240  and the printing medium  110  against the platen  246 , thereby transferring the regular color ink from the regular color ink film  240  to the printing medium  110  by heat and pressure. 
     In the above-described embodiments referring to FIGS. 1 and 2, the transfer roller  120  is positioned upstream relative to the thermal transfer printing sections  104  and  204  along the medium flow path  112  of the printing medium  110 . Such an arrangement may be desirable where, for example, the opaque ink on the ink film  122  is printed on the printing medium  110  first, and then the regular color ink on the regular color ink films  140  and  240  is printed on the printing medium  110  since the thermal transfer printers  100  and  200  can efficiently print the opaque ink as a background layer on the whole surface of one side of the printing medium  110 . 
     FIG. 3 is a cross-sectional view of a specific example of the ink film  122  used for the embodiments of the multilayer card and the method of manufacturing the multilayer card according to the present invention described referring to FIGS. 1 and 2. The ink film  122  includes a base film  300 , an adhesive layer  302 , and an opaque color layer  304 . The base film is made from plastic materials such as PET. The adhesive layer  302  is interposed between the base film  300  and the opaque color layer  304  for affixing the opaque color layer  304  to the base film  300 . The opaque color layer  304  includes at least one of “regular color layers” and “metallic layers.” 
     In this specification, “metallic ink” includes any ink which includes metallic substance such as metallic powder, metallic film or the like. Thus, the metallic ink includes, for example, gold color ink, silver color ink, and bronze (or copper) color ink. Similarly, a “metallic layer” includes any layer which carries metallic ink thereon. Thus, the metallic layer includes metallic substance such as metallic powder, metallic film or the like. “Regular color ink” means any ink other than the metallic ink, which includes, for example, cyan ink, magenta ink, yellow ink, black ink, and white ink. A “regular color layer” includes any layer which carries regular color ink thereon. 
     FIG. 4 is a cross-sectional view of a multilayer card  400  of a specific embodiment according to the present invention during the printing process. Before the printing process utilizing the thermal transfer printers  100  and  200 , the multilayer card  400  includes only the printing medium  110 . The specific embodiment of the method according to the present invention will now be described referring to FIGS. 1,  4  and  5 . 
     First, the thermal transfer printer  100  receives the multilayer card  400  from an opening provided on the housing  108 . The feeding rollers  130  and  132  feed the multilayer card  400  onto the transfer roller  120  and the platen  128  along the medium flow path  112 . Next, the transfer roller  120  transfers the opaque color layer  304  from the ink film  122  to an upper surface of the printing medium  110  of the multilayer card  400 . A transferred opaque color layer  404  is affixed to the printing medium  110  by heat and pressure which are applied by the transfer roller  120 , the heater  124 , and the platen  128 . Then, an adhesive layer  406  is applied to a surface of the transferred opaque color layer  404  for improving adhesiveness between the transferred opaque color layer  404  and regular color layers printed on the transferred opaque color layer  404 . 
     FIG. 5 is a cross-sectional view of the multilayer card  400  of the specific embodiment according to the present invention after the printing process. After printing the opaque color layer  404 , the feeding rollers  164  and  166  feed the multilayer card  400  onto the intermediate transfer roller  158  and the platen  160  along the medium flow path  112 . The multilayer card  400  is positioned on a predetermined point on the medium flow path  112  by using the sensor  162  and the feeding roller  164  controlled by the controller  106 . Then, the feeding rollers  164  and  166  feed the multilayer card  400  onto the intermediate transfer roller  158  and the platen  160  along the medium flow path  112 . The intermediate transfer roller  158  presses the intermediate transfer film  148  and the multilayer card  400  against the platen  160 , thereby transferring a cyan color layer  502 , a magenta color layer  504 , a yellow color layer  506 , a black color layer  508 , and a white color layer  510  from the intermediate transfer film  148  to a surface of the adhesive layer  406 . The order of printing the regular color layers may be modified appropriately. It should be appreciated that one or more layers among the cyan color layer  502 , the magenta color layer  504 , the yellow color layer  506 , the black color layer  508 , and the white color layer  510  may be omitted to be printed on the multilayer card  400 . 
     The specific embodiment of the method according to the present invention described above referring to FIGS. 1,  4  and  5  can be implemented by utilizing the thermal transfer printer  200  illustrated in FIG. 2 in a similar manner except that the regular color printing is performed by the thermal transfer printing section  204  rather than the thermal transfer printing section  104 . Thus, further detail is omitted. 
     In the specific embodiments described above, the regular color printing by the thermal transfer printing sections  104  and  204  can be implemented by a single thermal head. However, it should be appreciated that a plurality of thermal heads can be used for the regular color printing. 
     FIG. 6 is a cross-sectional view of a multilayer card  600  of a specific embodiment of the present invention. Now referring to FIGS. 1,  2  and  6 , a specific embodiment of the method for manufacturing a multilayer card according to the present invention will be described. This specific embodiment of the invention utilizes one of the thermal transfer printers  100  and  200 . Before the printing process utilizing the thermal transfer printers  100  and  200 , the multilayer card  600  includes only a base layer  602  which corresponds to the printing medium  110  in FIGS. 1 and 2. 
     First, the thermal transfer printer  100  receives the multilayer card  600  from an opening provided on the housing  108 . The feeding rollers  130  and  132  feed the multilayer card  600  through the transfer roller  120  and the platen  128  along the medium flow path  112 . The multilayer card  600  is positioned on a predetermined point on the medium flow path  112  by using the sensor  162  and the feeding roller  164  controlled by the controller  106 . Then, the feeding rollers  164  and  166  further feed the multilayer card  600  onto the intermediate transfer roller  158  and the platen  160  along the medium flow path  112 . The thermal transfer printing section  104  transfers a watermark layer  604  from the intermediate transfer film  148  to the multilayer card  600 . The watermark layer  604  is at least partially transparent and thus functions as a watermark for avoiding counterfeiting. The watermark layer  604  includes at least one of an ultraviolet (UV) ink layer, a holographic layer, and a special ink layer for improved security. 
     Second, the multilayer card  600  is again positioned on a predetermined point on the medium flow path  112  by using the sensor  162  and the feeding roller  164  controlled by the controller  106 . The feeding rollers  164  and  166  feed the multilayer card  600  onto the intermediate transfer roller  158  and the platen  160  along the medium flow path  112 . On top of the watermark layer  604 , the thermal transfer printing section  104  transfers an image layer  606  from the intermediate transfer film  148  to the multilayer card  600 . The image layer  606  includes at least one of the metallic ink and the regular color ink as described above in connection with the opaque color layer  304 , by which various images including characters and graphics are represented. 
     Then, the feeding rollers  130 ,  132 ,  164  and  166  feed the multilayer card  600  back onto the transfer roller  120  and the platen  128  along the medium flow path  112 . The transfer roller  120  transfers the opaque layer  304  from the ink film  122  to a top surface of the image layer  606  of the multilayer card  600 . The opaque layer  304  is affixed to the multilayer card  600  by heat and pressure which are applied by the transfer roller  120 , the heater  124 , and the platen  128 . A transferred opaque layer  608  includes at least one of metallic color layers and regular color layers, thereby functioning as a background layer on which the image layer  606  is printed. 
     Finally, the multilayer card  600  shown in FIG. 6 is moved along the medium flow path  112  from left to right in FIG.  1  through the feeding rollers  164 ,  166 ,  170  and  172  for ejection from the housing  108  of the thermal transfer printer  100 . 
     The specific embodiment of the present invention described above referring to FIGS. 1 and 6 can be implemented by utilizing the thermal transfer printer  200  illustrated in FIG. 2 in a similar manner except that the regular color printing is performed by the thermal transfer printing section  204  rather than the thermal transfer printing section  104 . Thus, further detail is omitted. 
     In the specific embodiments described above, the image layer printing by the thermal transfer printing sections  104  and  204  can be implemented by a single thermal head. However, it should be appreciated that a plurality of thermal heads can be used for the regular color printing. 
     FIG. 7 is a cross-sectional view of a multilayer card  700  of another specific embodiment of the present invention. Now referring to FIGS. 1,  2  and  7 , another specific embodiment of the method for manufacturing a multilayer card according to the present invention will be described. This specific embodiment of the invention utilizes one of the thermal transfer printers  100  and  200 . In this embodiment, further printing on the multilayer card  600  is performed utilizing one of the thermal transfer printers  100  and  200 . 
     After the printing process described referring to FIGS. 1,  2  and  6  is finished, the multilayer card  600  is retained within the housing  108  without ejection from the housing  108 . 
     First, the multilayer card  600 , i.e., a lower part of the multilayer card  700  is positioned on a predetermined point on the medium flow path  112  by using the sensor  162  and the feeding roller  164  controlled by the controller  106 . The feeding rollers  164  and  166  feed the multilayer card  700  onto the intermediate transfer roller  158  and the platen  160  along the medium flow path  112 . On top of the opaque layer  608 , the thermal transfer printing section  104  transfers an image layer  702  from the intermediate transfer film  148  to the multilayer card  700 . The image layer  702  includes at least one of the metallic ink and the regular color ink as described above in connection with the opaque color layer  304 , by which various images including characters and graphics are represented. 
     Second, the feeding rollers  130 ,  132 ,  164 ,  166 ,  170  and  172  feed the multilayer card  700  back to the sensor  162 . The multilayer card  700  is positioned on a predetermined point on the medium flow path  112  by using the sensor  162  and the feeding roller  164  controlled by the controller  106 . Then, the feeding rollers  164  and  166  further feed the multilayer card  600  onto the intermediate transfer roller  158  and the platen  160  along the medium flow path  112 . The thermal transfer printing section  104  transfers a watermark layer  704  from the intermediate transfer film  148  to the multilayer card  700 . The watermark layer  704  is at least partially transparent and thus functions as a watermark for avoiding counterfeiting. The watermark layer  704  includes at least one of an ultraviolet (UV) ink layer, a holographic layer, and a special ink layer for improved security. 
     Then, the feeding rollers  130 ,  132 ,  164 ,  166 ,  170  and  172  again feed the multilayer card  700  back onto the transfer roller  120  and the platen  128  along the medium flow path  112 . The transfer roller  120  carries a base layer film  822  instead of the ink film  122 . FIG. 8 is a cross-sectional view of a specific example of the base layer film  822  used for the embodiments of the multilayer card and the method of manufacturing the multilayer card according to the present invention described referring to FIGS. 1 and 2. The base layer film  822  includes the base film  300 , the adhesive layer  302 , and a base layer  706 . The base film  300  is made from plastic materials such as PET. The adhesive layer  302  is interposed between the base film  300  and the base layer  706  for affixing the base layer  706  to the base film  300 . 
     The transfer roller  120  transfers the base layer  706  to a top surface of the watermark layer  704  of the multilayer card  700 . The base layer  706  is affixed to the multilayer card  700  by heat and pressure which are applied by the transfer roller  120 , the heater  124 , and the platen  128 . 
     Finally, the multilayer card  700  shown in FIG. 7 is moved along the medium flow path  112  from left to right in FIG.  1  through the feeding rollers  164 ,  166 ,  170  and  172  for ejection from the housing  108  of the thermal transfer printer  100 . 
     The specific embodiment of the present invention described above referring to FIGS. 1 and 7 can be implemented by utilizing the thermal transfer printer  200  illustrated in FIG. 2 in a similar manner except that the regular color printing is performed by the thermal transfer printing section  204  rather than the thermal transfer printing section  104 . Thus, further detail is omitted. 
     In the specific embodiments described above referring to FIGS. 6 and 7, the base layer  602  corresponding to the printing medium  110 , and the base layer  706  are made from substantially transparent materials including suitable polymers such as PVC, PC, ABS, PPS and PETG. Alternatively, the base layers  602  and  706  may be semi-transparent so that at least part of the image layers  606  and  702  can be seen from the sides of the base layers  602  and  706 , respectively. 
     In the specific embodiments described above referring to FIGS. 6 and 7, the opaque layer  608  is made from materials including resin, cellulose, and ceramics. The opaque layer  608  is not substantially transparent, and functions as a substantially continuously and solidly filled background against which images on the image layers  606  and  702  can be seen. In some embodiments, the thickness of the opaque layer  608  ranges from about 3 μm to about 10 μm, and the thickness of the base layers  602  and  706  ranges from about 0.5 mm to about 1.0 mm. 
     As described above referring to FIGS. 6 and 7, the base layer  602  and the opaque layer  608  are capable of protecting the watermark layer  604  and the image layer  606 , and the base layer  706  and the opaque layer  608  are capable of protecting the watermark layer  704  and the image layer  702 . Thus, a specific embodiment of the multilayer card of the present invention is advantageous especially when tamper-proof and/or scratch-proof cards are necessary. Furthermore, such a specific embodiment is advantageous to enable a user to see the watermark layer  604  and the image layer  606  through the base layer  602 , and to see the watermark layer  704  and the image layer  702  through the base layer  706 . 
     The card  600  in FIG. 6 provides an image and watermark on one side of the opaque layer  608 . By printing the watermark and image directly on the base layer  602  and printing the opaque layer  608  on the image layer  606 , this embodiment may provide a more tamper proof card. The card  700  in FIG. 7 may provide base layers, watermarks, and images on two sides of the opaque layer  608 , which may provide a card that may be even more difficult to counterfeit. 
     In the specific embodiments described above, the image layer printing by the thermal transfer printing sections  104  and  204  can be implemented by a single thermal head. However, it should be appreciated that a plurality of thermal heads can be used for the regular color printing. For example, five separate thermal heads can be used for five colors (e.g., cyan, magenta, yellow, and black and white) for the thermal transfer printing sections  104  and  204 . 
     In the above-described thermal transfer printer used for the embodiment of a multilayer card according to the present invention described referring to FIGS. 1 and 2, the feeding rollers  130 ,  132 ,  164 ,  166 ,  170  and  172  are appropriately positioned along the medium flow path  112  so that the position of the printing medium  110  is controlled to go back and forth along the medium flow path  112  based on a specific printing process (e.g., watermark layer printing, image layer printing, and opaque layer printing) which is applied to the printing medium  110 . 
     In the above examples of the thermal transfer printer used for the multilayer card according to the present invention described referring to FIGS. 1 and 2, the controller  106  can be implemented by any combination of software and/or hardware. For example, the controller  106  can be implemented by a microprocessor, a memory device which stores instruction codes and data, and an interface which drives external devices such as the feeding rollers, the transfer roller, and the intermediate transfer roller. 
     Although only a few embodiments of the present invention have been described in detail, it should be understood that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention. For example, although the illustrated embodiments have been described primarily in the context of a multilayer card, it should be appreciated that various shapes of materials may be used for embodiments of the multilayer card and the method for manufacturing the multilayer card according to the present invention. Therefore, it should be apparent that the above described embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope of the appended claims.