SECURITY DOCUMENT WITH TRANSPARENT WINDOW

Description

[0001] The invention relates to the security of sovereign documents or other official identification documents, such as passports or identity cards, equipped with a visible security feature in the form of a transparent window made in the document. ÉTAT DE LA TECHNIQUE

[0002] Security documents such as passports, identity cards or others are often provided with a graphic design or image, for example a photograph of the holder obtained by printing.

[0003] One of the problems posed by this type of document lies in the relative ease with which they can be counterfeited by forgers, for example by separating or substituting the layers that form a card or any other laminated thermoplastic material presenting a function of identity document (in particular a polycarbonate data page for a passport).

[0004] To create these falsified documents, the forger alters the printed data, replacing it with false information. To do this, they typically separate the layers of an original official document, allowing them to sand away the old security features and then reconstruct a new document complete with new graphic data.

[0005] The process of cleaving security paper or plastic layers is very widespread and allows the forger to modify or partially redo the appearance of a security document.

[0006] To make this falsification more difficult, it is known to complicate the structure of the security document by making micro-perforations in it, or by inserting one or more transparent windows, the production of which requires specific industrial means.

[0007] This is how the principle of having a transparent window on a thermoplastic substrate for an identity document or on paper for banknotes became a security standard for these documents. The transparent window constitutes a level 1 security feature, meaning it is perfectly visible to the naked eye.

[0008] But to date several technical solutions exist for the production of these transparent windows, and they produce contrasting results.

[0009] The so-called "cap" method involves inserting a transparent polycarbonate cap between transparent areas of the product's outer layers. However, this cap is difficult to position, and achieving a high manufacturing yield for this assembly is challenging.

[0010] The so-called molding method involves directly molding a transparent insert, then machining this insert to add opaque layers that have been pre-cut to leave a transparent window. However, this technique requires very specific laminating plates, so existing production lines must be substantially modified.

[0011] The best method to date appears to be the so-called creep method. It consists of inserting one or more opaque layers with pores between layers of transparent material. If there are multiple opaque layers, these pores are positioned opposite each other. During the assembly and lamination of the layers, the applied temperature and pressure cause the material from the transparent layers to flow into the pores of the opaque layers, filling them. The pores filled by creep and the adjacent transparent areas then form a transparent window.

[0012] This method makes it possible to create transparent windows of any shape, while using standard production equipment.

[0013] However, successful creep requires adherence to several constraints. In particular, opaque layers with pores must be exceptionally thin, on the order of 30 micrometers, to allow creep to fill the pores and form a transparent window. However, handling these very thin layers is all the more delicate, as explained in more detail in relation to the... figures 1 et 2 .

[0014] Furthermore, this technique does not allow sufficient creep when the security document is partitioned, for example, when it includes an intermediate layer such as a PET layer with an antenna in the case of documents with radio frequency communication capabilities, or an aluminum layer forming a hinge in the case of a passport data page. Indeed, in these cases, the creep of transparent material towards the openings in the opaque layer only occurs on one side of the product, so some openings will not be filled or will be only partially filled, and the transparent window will be poorly formed.

[0015] An example of a document with a transparent window obtained by creeping transparent layers into an opening in an opaque layer is described in document DE 10 2015 010 811 A1 (Veridos GmbH), which discloses the preamble of claim 1. The problem addressed by this document is to obtain a transparent window in which at least one external face has a security feature in the form of a slight micrometer-scale relief. This security feature is the residual imprint left during the lamination phase of the document by a very slightly raised structure present on one face of the laminating plates.This relief structure is therefore very fine, on the order of micrometers like the residual imprint it must leave, and it is neither intended nor capable of causing a creep of material from the transparent layers that is sufficient to form a transparent window entirely filled with material resulting from the creep from the transparent layers adjacent to the opaque layer provided with an orifice. BUT DE L'INVENTION

[0016] A general aim of the invention is therefore to propose a new method for manufacturing security cards or documents such as identity documents with at least one transparent window, which is capable of overcoming the disadvantages of known methods.

[0017] An additional objective of the process is to enhance the level of document security, while offering differentiation without significant additional cost compared to documents using known processes, and while using a maximum of conventional production equipment in order to offer competitive production costs and yields.

[0018] Another objective of the invention is to allow the use of less thin opaque layers, for example 50, 70, or 100 micrometers instead of 30 micrometers, and therefore easier to handle, without compromising the quality of the transparent window obtained. OBJET DE L'INVENTION

[0019] In principle, the invention involves using modified laminating sheets equipped with a raised element capable of locally pushing the transparent polycarbonate material into the orifices of the opaque layers, reliably and efficiently filling them during the temperature and pressure increase in the lamination phase. This allows for the formation of fully transparent windows, free of bubbles or defects, despite the presence of intermediate layers forming partitions within the document's thickness, such as a PET layer carrying an antenna.

[0020] To create a raised feature on the rolling plates, the invention provides several solutions, such as a galvanic protrusion made on at least one of the two metal rolling plates, located in the window area. However, the raised feature on the rolling plates can also be created by an added element, metallic or otherwise.

[0021] The shape of the raised element used to push material into the openings can be diverse and varied. One of the most suitable shapes is convex, but this is not the only option. The thickness of the raised element depends on the space to be filled; the volumetric ratio between the space to be filled and the raised element is preferably on the order of 1:1, which will allow for adequate filling of the areas to be filled without generating overpressure or deformation on the adjacent material layers.

[0022] The invention therefore relates to a security document having at least one transparent window, obtained using a process comprising steps consisting of: to arrange between two laminating plates a stack of material layers composed of at least one layer opaque to light and at least one layer transparent to light, said opaque layer having at least one orifice intended to form said transparent window of the document; to laminate the stack of layers between two of said laminating plates by applying to said laminating plates a predefined pressure and temperature so as to cause material to creep from said at least one transparent layer towards the orifices of said at least one opaque layer; and at least one of the laminating plates having a raised element positioned opposite said orifices and capable of pushing, during lamination, a portion of the material from said at least one transparent layer towards said at least one orifice to form a transparent window in the security document;said raised element having a square, rectangular or convex cross-section and a volume substantially equivalent to the volume of the openings to be filled, so as to fill the volume of the window during lamination with the material of said at least one transparent layer, the security document being characterized in that said transparent window is provided with two convex or concave indentations situated opposite each other and configured to generate an optical magnifying effect for a sign, character or image placed on or in said transparent window.

[0023] According to an advantageous embodiment, the security document comprises, on its outer face in contact with said embossed element during lamination, a slightly recessed area corresponding to the residual imprint of said embossed element of the laminating plate, and forming a tactile or visual security element of the document.

[0024] According to one embodiment, said relief element has a smooth surface, or a surface structured by particular shapes such as characters, logos or images.

[0025] According to one embodiment, the safety document comprises a transparent PET substrate provided with the coils of an antenna, first transparent layers arranged on either side of the substrate, opaque layers located above the first transparent layers and provided with orifices situated opposite each other, and second transparent layers located above the opaque layers and whose material is made to flow into the orifices of the opaque layers during the lamination operation so as to constitute a transparent window filled with material from said transparent layers.

[0026] According to a practical embodiment, the transparent substrate has a thickness of between 40 and 80 micrometers, the first transparent layers have a thickness of between 70 and 150 micrometers, the opaque layers have a thickness of between 30 and 100 micrometers, and the second transparent layers have a thickness of between 100 and 150 micrometers. DESCRIPTION DETAILLEE DE L'INVENTION

[0027] Other features and advantages of the invention will become apparent upon reading the detailed description and accompanying drawings, in which: There figure 1 represents a cross-sectional view of a safety document manufactured using a creep process conforming to the prior art; The figure 2 represents a photograph of a transparent window in a security document manufactured using a process conforming to the state of the art; The figure 3A represents a cross-sectional view of a safety document prior to the lamination phase, comprising a single opaque layer and arranged between modified lamination plates to implement a first embodiment of the process related to the invention; The figure 3B represents a cross-sectional view of the document of the figure 3A , after the rolling phase; The figure 4A represents a cross-sectional view of a safety document prior to the lamination phase, comprising two opaque layers and arranged between laminating plates modified to implement a second embodiment of the process related to the invention; The figure 4B represents a cross-sectional view of the document of the figure 4A , after the rolling phase; The figure 5A represents a cross-sectional view of a safety document prior to the rolling phase, arranged between rolling plates modified to implement a third embodiment of the process related to the invention; The figure 5B represents a cross-sectional view of the document of the figure 5A , after the rolling phase; The figure 6 represents a perspective view of a security document in which the transparent window area is obtained using the manufacturing process related to the invention; The figure 7A represents a cross-sectional variant of a safety document prior to the lamination phase, arranged between lamination plates modified to implement a fourth embodiment of the process related to the invention, and comprising a single perforated opaque layer and a central PET layer; The figure 7B represents a cross-sectional view of the document of the figure 8A , after the rolling phase; The figure 8A represents another variant seen in cross-section of a safety document before the rolling phase, between rolling plates modified to implement a fifth embodiment of the process related to the invention, the particularity of which is to have reliefs on both rolling plates; The figure 8B represents a cross-sectional view of the document in Figure 9A, after the rolling phase; The figure 9 represents an exploded perspective view of a multi-layered security document to which the process related to the invention can be applied.

[0028] In the remainder of this document, for the sake of simplicity, we will consider that the secure document is a smart card (particularly in the so-called ID1 format), without limiting the invention to this single type of security document.

[0029] Indeed, the invention can perfectly also be applied to products of so-called ID2 or ID3 formats such as a polycarbonate data page used to make a passport, or to any other document format.

[0030] The methods of implementation of figures 3 à 9 do not represent the claimed invention, but are useful for understanding it.

[0031] We refer to the figure 1 This figure represents a cross-section of a smart card with a transparent window produced by a conventional lamination and creep process in accordance with the prior art. The card body comprises three layers 12 of transparent material 100 to 150 micrometers thick, for example polycarbonate, and two layers 13 of opaque material approximately 30 micrometers thick, for example PET, each with a hole. The two holes are superimposed and of different sizes. During the lamination phase, the polycarbonate of the transparent layers 12 softens and flows towards the holes, as schematically indicated by the arrows. However, in a common case (not shown) where the product also includes an intermediate layer without a hole (for example, a PET layer carrying an antenna), this creep is incomplete, so that the transparent window obtained by fusing the transparent layers in the area of ​​the holes is of poor quality.Even when the opaque layers are very thin, on the order of 30 micrometers, which makes them difficult to handle, the simple creep obtained by applying uniform pressure is insufficient to obtain a uniform and properly filled transparent window.

[0032] The result of insufficient creep is visible in plan view in the figure 2 , which represents a transparent window obtained as part of the process illustrated in figure 1 As can be seen, the resulting window contains a series of bubbles or irregularities 20, which impair good transparency and also detract from the aesthetics of the product.

[0033] In figures 3A et 3B The principle related to the invention is illustrated. figure 3A The product comprises two transparent, printed layers 4 (e.g., polycarbonate) situated on either side of an opaque central layer 3, for example, a layer carrying antenna tracks. Transparent protective overlayers 5 may surround the transparent layers 4. The central layer 3 has a central cutout 6 into which it is difficult to flow sufficient material from the transparent layers 4 using conventional lamination processes.

[0034] To overcome this difficulty, the process provides for equipping the inner face of at least one of the rolling plates 30, 31, in this case the lower rolling plate 31, with a raised element 32 having a suitable configuration. During the rolling phase, this element allows sufficient material from the transparent layer 4 located between the central layer 3 and the rolling plate 31 to be pushed into the cutout 6, so as to form a monolithic and well-filled transparent window 34 in the laminated assembly 33, as shown in figure 3B . For this purpose, the volume of the raised element must be close to the volume of the orifice to be filled, or even very slightly greater, which will guarantee an overpressure of material in the window during creep, and the absence of parasitic bubbles.

[0035] In addition, the rolling operation using a plate 31 provided with a raised element 32 leaves a residual indentation 35 on the rolled complex 33, which can constitute a signature of the use of the process.

[0036] Depending on the possible texturing of the surface of the embossed element 32, for example using an embossed logo or equivalent, the imprint 35 can constitute a signature or a personalized seal. An example of such an imprint is shown in figure 6 , in which the identity document 60 has a transparent window 62 whose perimeter 61 is a recessed or raised imprint corresponding to a corresponding relief or recess of the raised element of the rolling plate.

[0037] The process is also applicable for obtaining products with more layers, as shown in figures 4 , 5 , 7 , 8 .

[0038] In figure 4A The product comprises a transparent central layer 1, for example a PET layer carrying antenna tracks, surrounded on both sides by transparent layers 2 (for example polycarbonate), opaque layers 3 provided with openings 6, 7 of differentiated sizes and located opposite each other, printed outer layers 4, and finally a transparent protective overlayer 5. The central layer 1 forms a barrier which prevents the polycarbonate of the adjacent layers 2 from migrating and flowing and fusing towards the places necessary to fill the spaces created by the cutouts 6, 7 to constitute the transparent window.

[0039] To remedy this, as shown in figure 4A The product is arranged between two rolling plates 40, 41. The lower rolling plate 41 has a raised element 42 aligned with the holes 6, 7 of the opaque layers 3. In the example shown, the raised element 42 has a rectangular cross-section, but other shapes are possible.

[0040] In order to obtain optimal creep of the transparent material towards the window, the volume of the raised element 42 must again be substantially equal to, or even very slightly greater than, the cumulative volume of the orifices or cutouts 6,7 to be filled.

[0041] The embossed elements 32, 42, 52, 72, 82, and 83 can be produced economically and precisely on rolling plates in various ways. According to a highly efficient and durable embodiment, the embossed elements can be obtained directly from electroplating of the rolling plate metal, optionally followed by a precision engraving step to accurately adapt the shape of the embossed element and any logos or characters printed on its surface.

[0042] Alternatively, the raised element can be an added piece attached to the plate by gluing or another method of attachment. The material of this raised element can then be metal, Teflon, polyester, or an equivalent.

[0043] During the rolling phase, adapted according to several criteria such as the number of layers in the structure to be rolled, pressure is applied via the rolling plates with successive increments, from approximately 12 N / cm² at the press closure to over 150 N / cm² at the highest increment. A gradual temperature increase occurs, from approximately 40°C to over 185°C at the hottest point, for an average duration of about 30 minutes. The various layers then soften, and the raised element 42 locally deforms the transparent layers 2, 4, and 5, causing localized creep of the material in these layers. This results in the filling of the orifices 6 and 7, forming a transparent window 44, as shown in... figures 4B , 5B , 7B , 8BWhen, after cooling, the rolling plates 40, 41 are removed, in place of the raised element 42, there remains a hollow imprint 45, which constitutes a residual tactile and visual signature linked to the use of the process.

[0044] Obtaining a good quality transparent window, as well as the subsistence of the 45 imprint, will prove to a document verifier, for example Law Enforcement checking a passport, that the document is indeed an original and was obtained by the process.

[0045] THE figures 5A et 5B represent a variant of the implementation of the process figures 4A, 4B , wherein the raised element 52 has the shape of a convex disc with a curved cross-section, which will leave in the product 53 a specific recessed imprint, in particular the recessed imprint 61 shown in the figure 6 .

[0046] THE figures 7A et 7B represent another variant of the implementation of the process figures 4A, 4B in which the orifices 6, 7 are made respectively in an antenna support 1 and in an opaque layer 3, and the raised element 72 of the lower rolling plate 71 has a rectangular cross-section and leaves a recessed imprint 75 in the laminate complex 73. The resulting transparent window 74 does not pass through the entire laminated product, which allows a figure or characters printed on the upper opaque layer to be seen through the window 74, at the bottom of the window 74.

[0047] THE figures 8A et 8B represent yet another variant of the implementation of the process figures 4A, 4B , in which orifices 6, 7 of different sizes are made in opaque layers 3, and each of the rolling plates 80, 81, respectively has a raised element 82, 83 of size and shape adapted so that the laminated complex 84 has a transparent window 85 through the whole of the laminated complex 84 and leaves on the surface of this window 85 differentiated impressions 86, 87.

[0048] The surface of the embossed element 32, 42, 52, 72, 82, 83 can be smooth. However, it is also possible and advantageous for this surface to be irregular, for example, featuring characters, a logo, or other specific designs, which will be reflected in negative on the imprint left on the product after the lamination phase.

[0049] There figure 9 represents an exploded view of an example of a multilayer chip-type product which has 3 layers with 6,7 cutouts to create a transparent window, and which can take advantage of the process. AVANTAGES DE L'INVENTION

[0050] The invention achieves its stated objectives. The method according to the invention makes it possible to increase the security of a sovereign document, while retaining the possibility of easy visual verification by the authorities, without any specific reader.

[0051] The process is also economical insofar as it does not involve new manufacturing equipment or expensive components, but simply the addition of a raised element on the rolling plates opposite the transparent window to be made.

[0052] The invention makes it possible to complicate any possible attempt at illicit reproduction, due to the addition of the residual imprint 45 which constitutes a security element by introducing a slight visual and tactile difference which attests to the use of the process according to the invention.

[0053] In addition, the new process allows the use of thicker opaque layers, for example 50 micrometers thick, and therefore easier to handle, while obtaining a better quality transparent window thanks to improved creep.

[0054] The invention finds application in identity documents such as National Identity Cards (ID1 format), but the invention can perfectly also be applied to products of different formats and materials, for example of type so-called ID3, such as a "Data-page", or an electronic insert for passport, or even a multi-complexed security paper.

[0055] The products in question are those made of thermoplastic materials such as polycarbonate, PVC, PEC, or PETG.

[0056] A significant differentiation can be achieved through the customization of windows, in terms of their shape, size, and the resulting visual and tactile effects. Combining and layering multiple techniques will allow clients and law enforcement to easily verify access through simple tactile and visual inspection.

Claims

1. A security document provided with at least one transparent window (34; 44; 54; 74; 85), obtained using a method including steps of: - arranging between two laminating plates (30, 31; 40, 41; 50, 51; 70, 71; 80, 81) a stack of layers of materials composed of at least one layer (1, 3) opaque to light and at least one layer (2, 4, 5) transparent to light, said opaque layer (1, 3) including at least one orifice (6, 7) intended to form said transparent window of the document; - proceeding with the lamination of the stack of layers (1, 2, 3, 4, 5) between two of said laminating plates by applying to said laminating plates predefined pressure and temperature so as to cause creeping of the material of said at least one transparent layer (2, 4, 5) towards the orifices (6, 7) of said at least one opaque layer (1, 3); - and at least one of the laminating plates (30, 31; 40, 41; 50, 51; 70, 71; 80, 81) including a relief element (32; 42; 52; 72; 82, 83) positioned opposite said orifices (6, 7) and able to push back during lamination a portion of the material of said at least one transparent layer (2, 4, 5) towards said at least one orifice (6, 7) to form a transparent window (34; 44; 54; 74; 85) in the security document; - said relief element (32; 42; 52; 72; 82, 83) having a square, rectangular or cambered cross-section and a volume substantially equivalent to the volume of the orifices (6, 7) to be filled, so as to fill during lamination the volume of the window (34; 44; 54; 74; 85) with the material of said at least one transparent layer (2, 4, 5), characterized in that said transparent window (85) is provided with two convex or concave imprints (86, 87) located opposite one another and configured to generate a magnifying optical effect for a sign, a character or an image arranged on or in said transparent window (85).

2. The security document according to claim 1, characterized in that it includes a transparent substrate (1) made of PET provided with the turns of an antenna, first transparent layers (2) arranged on either side of the transparent substrate (1), opaque layers (3) located above the first transparent layers (2) and provided with orifices (6, 7) located opposite one another, and second transparent layers (4) located above the opaque layers (3), and the material of the transparent layers (2, 4) being brought to creep into the orifices (6, 7) of the opaque layers (3) during lamination so as to form said transparent window (34; 44; 54; 74; 85) filled with material originating from said transparent layers (2, 4).

3. The security document according to claim 2, characterized in that said transparent substrate (1) has a thickness comprised between 40 and 80 micrometers, the first transparent layers (2) have a thickness comprised between 70 and 150 micrometers, the opaque layers (3) have a thickness comprised between 30 and 100 micrometers, and the second transparent layers (4) have a thickness comprised between 100 and 150 micrometers.

4. The security document according to claim 1, characterized in that it includes, on its outer face in contact with said relief element (32; 42; 52; 72; 82, 33) during lamination, a slightly recessed area (35; 45; 55; 75; 86, 87) corresponding to the residual imprint of said relief element, and forming a tactile security element of the document.

5. The security document according to claim 4, characterized in that said relief element (32; 42; 52; 72; 82, 33) has a smooth surface, or a surface structured by particular shapes such as characters, logos or images.