Abstract:
The invention relates to an enhanced security feature for identification document. For that, the identification document comprises at least two constitution layers, a first specific coating ( 15 ) inside the document, between two constitution layers, said coating being able to be revealed under predetermined lighting conditions. It comprises also an assembly of micro-holes ( 16 ) provided through at least one of the layers, in order to make possible the revelation of the first specific coating under said predetermined conditions, said assembly of micro-holes, together with said coating to be revealed through micro-holes, drawing said security pattern.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a Section 371 of International Application No. PCT/IB2009/054081, filed Sep. 17, 2009, which was published in the English language on Mar. 25, 2010, under International Publication No. WO 2010/032208 A1, and the disclosure of which is incorporated herein by reference. 
     BACKGROUND 
     This invention relates generally to identification documents and a method for making such identification documents. More particularly, this invention relates to a secure identification document that allows detecting a fraudulent modification of the existing personalization or a completely falsified document. The invention also relates to a method for making such a document. 
     Identification documents, such as driving licenses, identity cards, membership cards, badges or passes, passports, discount cards, banking cards, money cards, multi-application cards, and other papers of value; and security documents such as bank notes are widely used. Because of the value and importance associated with each of these data carriers, they are often the subject of unauthorized copying and alterations, and forgeries. 
     To prevent such activities from being carried out on these data carriers, different types of visual and touchable security features have been added to data carriers. One of these security features consists in providing, into the document, an optically variable security element, which comprises at least two security markings. Said markings are decomposed and interleaved, so as to create a complex image that is printed into the document. Then, a filter is placed over this complex image, said filter being arranged so that it enables to visualize each marking at a respective particular angle by tilting the document. 
     Another security feature consists in providing a personalized image that is perforated through a document, but not extending through the whole thickness of the document. For that, blind holes are perforated, and the desired brightness tones are obtained by varying the density and/or the diameter and/or the depth of these holes. This technology is for example described in the document EP0936975. 
     Still another security feature consists in applying specific inks, such as UV inks, or IR inks for instance, onto the top surface of the data carrier, so that a security pattern can be revealed under predetermined lightening conditions. However, because they are applied onto the external surface of the document, such inks suffer from the environmental stresses. Therefore, the use of such inks onto the surface of identification documents is not compliant with a long-term life, which is required for identification documents that are usually delivered for ten years. On the other hand, some of these inks, namely short-wavelength UV inks, are generally absorbed, more or less, by plastic layers, depending on their thickness. That&#39;s the reason why such inks are not used inside identification document, because they cannot be sufficiently seen through the plastic constitution layers, whatever they are transparent or opaque. 
     Considering the above, a problem intended to be solved by the invention is to improve the existing solutions, and to find alternative solution to existing security features for identification documents comprising at least two constitution layers. Said identification document is personalized with personalization data and is secured with a security pattern, which forms the security feature. The problem is to use any inks to make the security pattern, said inks being able to be revealed under predetermined specific conditions, said inks being applied inside the constitution layers and no more onto the external surface of a document, in order to protect them against environmental stresses, and able to be selectively revealed in spite of the layers placed above that may either hidden or greatly soften their appearance. 
     Another problem intended to be solved by the invention is to provide a method for manufacturing a secure identification document comprising at least two constitution layers, said document being personalized with personalization data and being secured with a security pattern, said method being easy, quick to implement, and of low cost. 
     SUMMARY 
     The solution of the invention to the first problem relates to the fact that the identification document comprises a first layer of specific coating inside the document, between two constitution layers, said coating being able to be revealed under predetermined lighting conditions, and an assembly of micro-holes provided through at least one of the layers, in order to make possible the revelation of the first specific coating under said predetermined conditions, said assembly of micro-holes together with said coating to be revealed through micro-holes, drawing said security pattern. 
     Thus, micro-holes are provided in order to remove the material hiding the specific coating, so as to make it possible to be revealed. Micro-holes are provided in such a manner that they draw a security pattern, which is revealed by the specific coating when enlightened under the predetermined conditions. 
     According to another aspect of the invention, there is provided a method for manufacturing a secure identification document comprising at least two constitution layers and being personalized with personalization data and being secured with a security pattern, said method comprising the following steps: providing, between two constitution layers, a first layer of specific coating, able to be revealed under predetermined lighting conditions, laminating together said two constitution layers and specific coating layer, providing micro-holes through at least one of the layers, in order to make possible to reveal first specific coating, said first specific coating to be revealed through said micro-holes forming an assembly that draws the security pattern. 
     The assembly of micro-holes may be made either at the last stage of the manufacturing, substantially simultaneously to the personalization step, or before the attachment of the layers to each other. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The invention will be better understood with reference to the drawings, in which: 
         FIGS. 1A and 1B , are schematic cross-sectional views of examples of identification document according a first embodiment of the invention, 
         FIG. 2 , is a cross-sectional view of an identification document according to a second embodiment of the invention, 
         FIGS. 3 to 7  are cross-sectional views of an identification document according to other embodiments of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Hereafter, embodiments of the present invention will be described in the context of identity (ID) card and a method for producing it. However, it is to be understood that the invention is usable with any data carrier that includes, but is not limited to, a driving license, a badge or pass, a booklet passport, a discount card, a membership card, a banking card, a credit card, a money card, a multi-application card, tickets, tax stamps, passes and other security documents and papers of value that are to be provided with information or data in such a way that they cannot be easily imitated by common means. Such document can be made with different appearance, such as card or booklet for instance. 
       FIGS. 1A and 1B  show cross-sectional views of an ID card comprising several constitution layers  11 ,  12 ,  13 ,  14 ,  18  made in either paper, or cardboard, or textile or polymer. Amongst the polymers that can be used in the composition of the card body, the material can be, but is not limited to, a Polyvinylchloride (PVC), and/or Polyethylene terephtalate (PET), and/or Acrylonitrile Butadiene styrene (ABS), and/or Polycarbonate (PC) etc. . . . . The wording “constitution layers” used in the present description must be understood as all types of layers, including also substrates, that are used for manufacturing the body of the document. All the layers  11 ,  12 ,  13 ,  14  and  18  are assembled together by means of lamination technology for example. In a well-working example, the layers are made in polycarbonate and they are laminated so that, during lamination step, they are fused together in such a manner that they form only one piece and they cannot be peeled anymore. 
     The ID card comprises another layer  15  of specific material that is placed inside the card body, between at least two constitution layers  12 ,  13 ,  18 , and that is completely hidden and not visible when looking at the card from the both sides. For having such hidden specific material, either the specific material used is a material that is not visible through other layers such as short-wavelength UV ink (typically around 300 nm or shorter), which is absorbed by plastic material, or the specific material is hidden by opaque layers or relatively thick at least translucent layers. Then, at one of the latest steps of the manufacturing of the card, i.e. at the personalization step for instance, this material can be revealed at specific areas, so as to create a security pattern. The specific coating  15  can be, but is not limited to, a fluorescent or bi-fluorescent ink, such as UV ink that reacts with a wavelength at either 302 nm or 254 nm for example, or a thermochromatic ink, or a circularly polarized ink or an IR ink etc. . . . . In the case of bi-fluorescent UV ink, for example, such ink is more or less filtered by upper plastic layers, whatever they are opaque or translucent, so that the ink is either completely hidden or its appearance is at least greatly reduced. In order to be sure that the ink is completely hidden, it can be placed between two opaque layers  12  and  13  (see  FIG. 1A ), or onto one of the surfaces of an at least translucent layer  18  placed between two opaque layers  12 ,  13  (see  FIG. 1B ). 
     Then, a security pattern can be made substantially simultaneously to the graphic personalization step. The personalization step consists in providing on the card, all the personalization data concerning the card owner. These data comprise for example the photograph of the owner, and information such as his name, address, birth date, and all other personal information. The personalization step is made using conventional techniques such as laser engraving or printing for example. The personalization data are either laser engraved into the layer  12  or printed onto the surface of the layer  12 , and then protected against environmental stresses by a transparent layer  11 , also called “overlay”. At substantially the same time, micro holes are provided through at least one of the layers of the card. In the example of  FIGS. 1A and 1B , the micro holes  16  are provided through several layers  11 ,  12 ,  13 ,  18 ,  15  including the ink layer  15 . These micro-holes can be made using all known technologies such as laser ablation, etching, engraving, punching, or drilling, etc. They can be provided through the whole thickness of the card or not. However, the obtained visual effect is a bit lower with holes provided through the whole thickness than with holes provided through some layers. In a variant of implementation, which will be detailed later, they can also be provided through at least one layer inside the document, and not through the upper external layers. 
     Thus, in examples illustrated on  FIGS. 1A and 1B , micro-holes being provided through the ink layer  15 , they enable to reveal the ink in areas  17  just around the holes. This ink is seen from the holes  16 . Thus, by providing several micro-holes, at specific locations, it is possible to draw a security pattern. In the example of a bi-fluorescent ink that reacts at 365 and 254 nm, the wavelength at 254 nm can only be revealed through the holes and is hidden otherwise, while the other wavelength at 365 nm can also appearing through an upper at least translucent plastic layer, if it is not to thick. The security pattern can be for example a ghost image of the photograph or it can reveal the contour of a photograph or a text, so that it is impossible to change the latter. Then the ink, which is thus revealed, can be seen from either both sides S 1  or S 2  with different appearance (i.e. ink will be more or less visible) depending on the lighting conditions, and more particularly depending on which side it is enlightened and from which side it is looked at. 
     Depending on the material used for the specific layer  15  to be revealed, the lighting material will be for example an UV lamp, or an IR lamp, or a polarized light etc. . . . . 
     The diameter of micro-holes is preferably less than 2 mm. Depending on the material used for the constitution layers and on the thickness of the constitution layers, they can be made either before or after the lamination step, in case where the layers are attached together by using this technology. In fact, if layers are made in polycarbonate, micro-holes can be made before the lamination step only if layers to be laminated have thickness less than 0.05 μm, otherwise the polycarbonate constituting the layers will smear and fill the micro-holes. Consequently, if the thicknesses of the polycarbonate layers are more than 0.05 μm, micro-holes are preferably made after lamination step. This constraint on pre-perforated layers to be laminated is only relevant for polycarbonate material, which is assembled by lamination. Indeed, if layers are made with other plastic material, such as PVC, ABS, PET for example, these layers are typically assembled using adhesives, in which case there is no strict upper limit for the thickness of pre-perforated layers. 
     With such document, if an attempt is made to peel the constitutions layers, for example layers  12 , and  13  in  FIG. 1A , it is then impossible for the forger to replace the layers in such a manner that the micro-holes of each layer face exactly each other, so that ink  15  is either no more revealed in areas  17  because hidden, or its revelation is considerably reduced. Consequently, such an attempt appears directly to naked eye. 
       FIG. 2  shows an even more secure embodiment. In this embodiment, after personalization step and after having providing the micro-holes  16 A,  16 B to reveal the ink  15  in areas  17  surrounding the holes, an additional and final step consists in attaching, for example by lamination, another layer  21  of an at least translucent plastic. The inner surface  22  of this layer  21  is covered by a specific material  19 , which is opaque at normal stage and which becomes invisible under specific circumstances. This specific material can be, but is not limited to, a thermochromatic ink, which is black at normal stage and becomes invisible when it is warmed to a specific temperature. The phase transition temperature of such an ink can be reached for example by a simple pressure of a finger. Another example of such a specific material  19  can be an ink sold by the security printing ink producer SICPA and known under the trademark name “Oasis” (for “Optically Active Secure Ink System”). This specific ink is opaque and hide the underneath layers, and it becomes invisible, when viewed through a polarization filter, and reveals the layers and the holes underneath, so as to show the fluorescent ink in the holes areas that draws the security pattern. Such embodiment using a specific material  19  which is opaque at normal conditions and becomes invisible under predetermined conditions, so as to reveal the layers, micro-holes  16 , and specific coating or ink  15  underneath through the micro-holes  16 , is very secure and enables to reveal the security pattern underneath in order to authenticate the ID document. 
       FIGS. 3 to 5  show other embodiments. In these embodiments, micro-holes are provided through layer(s) located above the layer  15  of specific coating or ink, but they are not made through this layer. Consequently, in order to be at least visible, this specific ink, for example an UV ink, must be covered at the most by a thin layer  11  at least translucent, so that it is not completely hidden. The ID document is manufactured by assembling all the layers  11 - 14  together including the layer of specific ink  15 , by using conventional technology. In order to further reveal the layer  15 , it must be seen through the remaining layer(s) located above (the layer  11  in example of  FIG. 3 ). Consequently, layer  11  must be made in a material at least translucent and at the most transparent and with a relatively thin thickness. 
     Then the thus obtained body of the document is graphically personalized. This personalization can be made either by laser engraving the layer  11 , if this layer is made with a material that is laser sensitive; or by printing the personalization data onto the surface of the layer  11 , by using a conventional printing technology. 
     In an additional step, a layer F is attached to the body. This layer, named filter in the following description, is made in a material that hide the underneath ink layer  15 , but not the personalized information. This filter layer does not hide anything else but the material  15  intended to be selectively revealed afterwards, at the final step of the manufacturing process. Consequently, normal personalization such as the photograph of the owner, or other alphanumeric data about his identity is normally visible in all cases. The last step then consists in providing micro-holes that are made through the filter layer thickness. These holes enable to reveal the material  15  located underneath, at locations  15 ′ under the holes  16 , through the at least translucent layer  11 , so that a security pattern can be drawn. 
     As it is described above, the specific material  15  intended to be revealed at the final stage of the manufacturing process, can be made of, but is not limited to, fluorescent ink or bifluorescent ink, IR ink, a metal foil, oasis ink from Sicpa, etc. . . . depending on the type of material used, it can be seen under predetermined condition, for example by enlighten it with an UV lamp at a specific wavelength, IR lamp, circularly polarized light etc. . . . . 
     The filter material can be made of different material, for example of an at least translucent plastic layer, such as PVC, PET, PC etc. . . . , with a thickness thick enough to hide the underneath layer  15 , or a polarizing filter etc. . . . . 
     In a variant, the holes are made directly into the protective layer, or overlay  11 , that is made of a suitably filtering material, thick enough polycarbonate for instance, either before or after it is applied onto the ID document. 
       FIG. 4  shows another variant of this embodiment, in which two filter layers F 1  and F 2  are used. Thus, the filtering strength being proportional to the thicknesses t 1  or t 2  of the remaining material above, the visibility of the layer  15  is only gradually reduced in areas  15 ′ and  15 ″, depending on the values of the small thicknesses t 1  or t 2  of the plastic material remaining above the ink layer  15 . With this variant, it is possible to achieve different shades instead of just binary marking. 
     Furthermore, in case a protective layer  25  is attached on top of the body, it can have another type of filter on/in it to enable to hide and/or reveal the underlying markings. This is illustrated on  FIG. 5 , where the protective layer  25  holds a special ink  26  onto its lower surface  27  located against the personalized surface and the holes  16 . Such ink  26  can be used to achieve yet other effects and in particular hide and reveal the micro-holes  16  and thus the revealed ink  15 ′ that draws a security pattern. 
     The special ink  26 , may be choose, but is not limited to, amongst either a thermochromatic ink, to hide the markings and have them revealed when heating/warming the ink with one&#39;s finger tips; or Oasis ink from Sicpa or others. 
       FIG. 6  shows another variant, in which the holes are obtained by laser ablation through another specific layer  30 . In this example, layers  13 - 14  form a substrate on which is printed the first specific coating  15  to be revealed. Then, a metal foil  30 , which can be holographic or not, is placed directly onto the first coating  15  and covered by at least one upper layer  11 . A laser beam is used to create the holes  16  into the thickness of the metallic foil in order to reveal the ink  15  underneath, at locations  15 ′, but not through the upper layer(s)  11 . In a particularly interesting embodiment, the metal foil used is a metallic holographic foil and once perforated it becomes unique to the document and its holder and thereafter cannot be used for counterfeiting any other documents. 
       FIG. 7  shows still another variant, according to which the specific coating  15  is covered by a laser-sensitive varnish  31 , itself printed with another specific coating or ink  32  designed to hide the first ink  15 . Then the varnish  31  reacts to laser beam, so that the second ink  32  can be selectively removed, thus revealing the first ink  15 , at locations  15 ′, without holes creation through the upper layer(s)  11 .