Safety document comprising a perforated metallic layer adjacent to at least part of a face of a colored sub-pixel matrix and manufacturing process.

Abstract

Security document comprising a perforated metallic layer adjacent to at least a portion of a face of a colored sub-pixel matrix and method of manufacture. The invention relates to a security document comprising a stack of layers including a colored sub-pixel matrix, a metallic layer adjacent to at least a portion of a face of the colored sub-pixel matrix, wherein the metallic layer has perforations opposite sub-pixels of the colored sub-pixel matrix. Figure for the abstract: Fig. 2a.

Description

Description Title of the invention: Security document comprising a perforated metal layer adjacent to at least a portion of one face of a matrix of colored sub-pixels and manufacturing method. Technical field

[0001] = The invention relates to the field of security documents, and in particular security documents on or within which images are observable. The invention applies non-exclusively to physical identity documents, such as a passport, identity card, driving license, residence permit, etc. Prior art

[0002] = The identity market today requires physical identity documents (so-called also identity documents or security documents) increasingly secure. This market concerns very diverse documents, such as identity cards, passports, access badges, driving licenses, etc., which can come in different forms formats (cards, booklets, etc.).

[0003] — Security documents must be easily and quickly authenticated. They must also be difficult to counterfeit (if possible unfalsifiable), and this, in the face of to the latest counterfeiting techniques.

[0004] — Security documents usually feature colored images, for example photographs of faces of a holder of the security document.

[0005] … Color imaging techniques for secure identity documents use colored subpixel matrices (e.g. with Red- Green-Blue or Cyan-Magenta-Yellow subpixels) and techniques for blackening a layer that will mask portions of subpixels to obtain pixels of one color desired.

[0006] — For example, it is known to use laserizable layers, as described in the prior document FR 2 972 553 in which a laserizable layer surmounts a matrix of colored subpixels.

[0007] — By laserizable, we mean that the application of a laser beam on the layer (commonly called laserization) generates gray levels visible by carbo- nization in this layer. For information, a laserizable layer can be a transparent polycarbonate layer and may contain additives sensitive to passage of a laser beam because this beam carbonizes them. Such a layer la- seriable will be blackened or at least partially grayed throughout its thickness depending on the laser power since the additives sensitive to the passage of a laser beam are distributed evenly throughout the thickness of the layer. Current color imaging techniques, such as those using laser-enabled layers, particularly in secure identity documents, do not always provide satisfactory visual rendering quality. Problems arise, in particular, when the imaging techniques used are limited in their ability to produce certain colors. In other words, the color gamut (variety of achievable colors) of known color imaging techniques is sometimes limited. There is a need for security documents with colored images that have a less limited color gamut. Statement of the invention To this end, the present invention proposes a security document comprising a stack of layers comprising a matrix of colored sub-pixels (SB, SM, SJ), a metal layer adjacent to at least part of a face of the matrix of colored sub-pixels, in which the metal layer comprises perforations facing sub-pixels of the matrix of colored sub-pixels. Thus, the invention proposes to use a metallic layer which is perforated to reveal certain colored sub-pixels. It is thus possible to form pixels of the image with colored sub-pixels under or on which a metallic layer is deposited and colored sub-pixels under or on which the metallic layer is perforated, which makes it possible to have a wider color gamut, and in particular brighter colors. In some embodiments, said metal layer comprising perforations is located only in a first window of said document In this way, it is possible to make only one part of the image brighter. This advantageously allows the color rendering outside the window to remain unchanged, compared to a normal rendering of the document, which is important when the document is a security document. In some embodiments, said metal layer is positioned above the array of colored sub-pixels. In some embodiments, said metal layer is positioned below the colored sub-pixel array. In this way, it is possible to choose the desired rendering on the front or back of the document, the position of the metallic layer on the front or back giving a different rendering in terms of brightness and contrast. In some embodiments, the metal layer is positioned above the pixel array in one or more windows of the document and below the pixel matrix in one or more document windows. In some embodiments, the image viewed in said window comprises at least a portion of an image viewed on a second window of said document, said second window being located on an area of ​​said document not comprising said perforated metal layer. This is particularly advantageous when the document represents an identity document. Indeed, the image represented in the window may be the face of the document holder and it is particularly advantageous to print the face in a window whose color gamut is enlarged so as to better distinguish the details. On the other hand, displaying an image with an enlarged gamut makes it more difficult to falsify the document because this image includes more details. In some embodiments, it may be envisaged to represent information other than the face, for example personal identification information of the bearer of the document, such as their marital status or information relating to the document, such as a registration number. In certain embodiments, it may also be envisaged to represent in the window part of the information present in another area of ​​the document, by changing their orientation, for example by rotating this information. In certain embodiments, said metallic layer is previously partially demetallized so as to adhere to the layer(s) between which it is inserted. This advantageously allows the layers to be sealed together more strongly because inserting a metal layer between two layers, such as polycarbonate, weakens the adhesion of the two polycarbonate layers to each other. Demetallizing part of the metal layer, even minimally, improves the assembly of the layers and thus the lifespan of the document over time. In some embodiments, said perforated metal layer is perforated so that the image viewed in said first window has a different visual rendering depending on whether said document is illuminated from the front face or from the rear face. The invention also relates to a method of manufacturing a security document in which a matrix of colored sub-pixels is assembled with a metal layer, adjacent to at least a portion of a face of the matrix of colored sub-pixels, the method further comprising the formation of performances through said metal layer opposite sub-pixels of the matrix of colored sub-pixels. Brief description of the drawings Other characteristics and advantages of the present invention will emerge from the description given below, with reference to the appended drawings which illustrate exemplary embodiments thereof which are not in any limiting nature. In the figures: [Fig.1] [Fig.1] represents a top view of a security document according to one embodiment of the invention, [Fig.2a] [Fig.2a] is a sectional view of security documents before perforation, according to an example, [Fig.2b] [Fig.2b] is a sectional view of security documents before perforation, according to an example, [Fig.3a] [Fig.3a] is a sectional view of security documents before perforation, according to an example, [Fig.3b] [Fig.3b] is a sectional view of security documents before perforation, according to an example, [Fig.4a] [Fig.4a] is a sectional view of the document of [Fig.3a] after perforation, [Fig.4b] [Fig.4b] is a sectional view of the document of [Fig.3b] after perforation, [Fig.5a] [Fig.5a] illustrates the phenomenon observed when observing the document according to certain embodiments, [Fig.5b] [Fig.5b] illustrates the phenomenon observed when observing the document according to certain embodiments, [Fig.5c] [Fig.5c] illustrates the phenomenon observed when observing the document according to certain embodiments, [Fig.5d] [Fig.5d] illustrates the phenomenon observed when observing the document according to certain embodiments, [Fig.6] [Fig.6] is a top view of the matrix of colored sub-pixels according to a first example, [Fig.7] [Fig.7] is a top view of the colored subpixel matrix according to a second example. Description of the embodiments We will now describe security documents comprising both a matrix of colored sub-pixels and a metallic layer, with an improved color gamut at least in terms of brightness over at least a portion of the security document. The images formed by these subpixels are customizable images, which can be different for each document, and which can be specific to each document user. The documents described here may be physical identity documents such as a passport, an identity card, a driver's license, a residence permit, etc. In fact, the documents described here may be associated with a user, and the colored images that will be obtained may be images of the users' faces. In [Fig. 1], a top view of a security document D according to an embodiment of the present disclosure is shown. The document D comprises general information, in particular information relating to the type of document, to a reference or identification of the document and also personal information relating to the bearer of the document. In order to improve the security of the document D, a window F comprises information whose brightness and contrast are different from the brightness and contrast of the other areas of the document D. Preferably, the contrast and brightness of the information present in the window F are improved for a human eye. According to some embodiments, the window F includes information visible from both sides of the document D. This can be made possible by the presence of transparent layers above and below the window F. According to some embodiments, the visual rendering of this information is different depending on whether the document is observed from its front side or its back side. According to some embodiments, the window F may include information not present on other parts of the document F. According to certain embodiments, the window F may include or repeat part of the information present on the document D. According to certain embodiments, this window F may also include part of the information present on the document D in a modified manner, for example with a rotation or at a different scale. This information may be, for example, the face of the bearer of the document D, or personal data, such as his civil status, for example his date of birth, his place of birth, physical distinctive signs. According to certain embodiments, several windows F may be present on the document D. These windows may include different information in each window (or in one or more windows) or the same information in each window (or in one or more windows) having a different contrast or brightness in several windows. Figures 2 to 5 illustrate embodiments in which sectional views of document D illustrate how a different visual rendering is obtained in window(s) F. In Figures 2a and 2b, a document 100, respectively 100°, obtained by assembling different layers, which may have been put implemented by means of lamination. Documents 100 or 100' may be a representation of document D of [Fig.1]. The document 100 or 100” particularly comprises a matrix of colored sub-pixels 101, for example a transparent or opaque layer on which colored elements have been printed, each forming colored sub-pixels. Here, the matrix of colored sub-pixels comprises sub-pixels having three possible colors, cyan sub-pixels SB, magenta sub-pixels SM, and yellow sub-pixels SJ. Here we find the three colors of the color model well known to those skilled in the art under the acronym CMY (“Cyan Magenta Yellow”). The invention is not limited to this color model and can also use a model such as the RGB model (“Red Green Blue” in English). Of course, other color triplets that differ from CMY and RGB can be used. The subpixels are arranged according to a matrix which will be described in more detail with reference to [Fig.6] or [Fig.7]. It can nevertheless be noted that a PM pattern of three subpixels SB, SM, and SJ is repeated several times in the section visible in Figures 2a to 5d. The documents 100 and 100* also optionally comprise a transparent layer 103, for example made of polycarbonate, as well as a transparent layer 104, for example made of polycarbonate. These two layers may be protective layers. The transparency of these protective layers makes it possible to observe the document 100 or 100” from its front face or its back face while viewing information present on one or other of the faces. In [Fig.2a], a metal layer 102 has been assembled above the matrix of colored sub-pixels. In [Fig.2b], a metal layer 102 has been assembled below the matrix of colored sub-pixels. This layer can be chosen so that perforations can be formed in this layer easily, for example by applying a laser beam with a given wavelength called the perforation wavelength. This layer 102 may consist of an opaque reflective metallic film, this metallic film being able for example to be produced by deposition of a metallic ink. Thus, the present disclosure relates to a security document comprising a stack of layers comprising a matrix of colored sub-pixels, a metal layer adjacent to at least part of a face of the matrix of colored sub-pixels, in which the metal layer comprises perforations facing sub-pixels of the matrix of colored sub-pixels. In Figures 3a and 3b, a document 1000, respectively 1000', obtained by assembling different layers, which may have been put implemented by means of lamination. Documents 100 or 100' may be a representation of document D of [Fig.1]. Documents 1000 and 1000' differ respectively from documents 100 and 100” in that the metal layer 102” is positioned on or under a portion, or window, of document 1000 or 1000 and does not cover the entire matrix of colored sub-pixels 101. According to certain embodiments, this metal layer 102' may be deposited on or under several portions or windows of document D. Figures 4a and 4b show the document 1000” after a step in which perforations are formed in the metal layer 102’ has been implemented. This step may include the application of a laser beam at the perforation wavelength. It should be noted that Figures 4a and 4b relate to the documents 1000 and 1000’, i.e. to the positioning of the metal layer on a portion of the sub-pixel matrix as shown in Figures 3a and 3b, but that of course this also applies to the documents 100 and 100” as shown in Figures 2a and 2b. At this point, we note that some colored subpixel patterns are associated with different perforations. From left to right in [Fig.4a], we observe: - A metal layer present above a yellow SJ subpixel, above an adjacent yellow SJ subpixel and a magenta SM subpixel, then above an adjacent yellow SJ subpixel and a magenta SM subpixel. From left to right in [Fig.4b], we observe: - A metal layer present below a yellow SJ subpixel, below an adjacent yellow SJ subpixel and a magenta SM subpixel, then below an adjacent yellow SJ subpixel and a magenta SM subpixel. The presence of this metallic layer above or below certain colored sub-pixels makes it possible to accentuate the brightness and contrast of the image formed by the colored sub-pixels. A colored image appears when looking at the document 1000 or 1000', with brighter colors than in the techniques according to the prior art. It can be noted that the combination of the patterns and the perforations forms image pixels, but, as will be described below, those obtained after the optional laserization step are called pixels. It is understood that the combination of the perforated metallic layer 102* makes it possible to obtain a very wide color gamut, in particular for the brightest colors. This is explained with reference to Figures 5a to 5d. We do not detail here the effect of lighting on the portions of the documents 1000 or 1000° which are not included in the window F because the metallic layer 102, respectively 102° is not present on these portions. [Fig.5a] shows a sectional view of the security document 1000 when it is illuminated from its rear face. The rear face of the document 1000 is exposed to a light source and more particularly the window F. The metal layer 102' present above the first yellow sub-pixel of the window F, starting from the left, blocks the transmission of light from the rear face to the front face of the document. Thus, the yellow component is no longer present in the pixel viewed on the front face and the combination of the adjacent cyan and magenta sub-pixels gives a blue color whose luminance and contrast are accentuated compared to the prior art or compared to the pixels located outside the window F. The metallic layer 102" present above the second yellow sub-pixel from the left of the window F and the adjacent magenta sub-pixel to its left, blocks the transmission of light from the back face to the front face of the document. Thus, the yellow and magenta components are no longer present in the pixel viewed on the front face and the combination of the adjacent cyan and yellow sub-pixels gives a green color whose luminance and contrast are accentuated compared to the prior art or compared to the pixels located outside the window F. This is also accentuated by the presence of the metallic layer above the magenta sub-pixel located to the right of the window. [Fig.5b] shows a sectional view of the security document 1000 when illuminated from its front face. The front face of the document 1000 is exposed to a light source and more particularly the window F. The metallic layer 102” present above the first and second yellow sub-pixels of the window F, prevents the light from reaching these yellow sub-pixels. Thus, the combination of the cyan and magenta sub-pixels located between these two yellow sub-pixels gives a pixel whose brightness is modified by this non-reflection of the light on the yellow sub-pixels framing them and gives a blue brightness with gray levels, NVG, the presence of gray being due to the gray color of the metallic layer present on the adjacent yellow sub-pixels. The 102” metal layer present above the second and third yellow sub-pixels from the left of window F and the adjacent magenta sub-pixel to its left, prevents light from reaching these magenta sub-pixels. Thus the combination of the cyan and yellow sub-pixels located between these two magenta sub-pixels gives a pixel whose brightness is modified by this non-reflection of light on the magenta sub-pixels framing them and gives a green brightness with gray levels, NVG, the presence of gray being due to the gray color of the metal layer present on the adjacent yellow sub-pixels. We can thus see that the presence of the metallic layer above the yellow or magenta sub-pixel (it would be the same if the sub-layer was located on one or more cyan sub-pixels) allows for a different light rendering depending on whether the document is lit from its front or back, making the reproduction of such a document more complex and thus improving its robustness in terms of security. [Fig.5c] shows a sectional view of the 1000” security document when illuminated from its rear face. The back of the 1000” document is exposed to a light source, and more specifically window F. The metallic layer 102" present below the first yellow sub-pixel of the window F, starting from the left, blocks the transmission of light from the back face to the front face of the document. Thus, the yellow component is no longer present in the pixel viewed on the front face and the combination of the adjacent cyan and magenta sub-pixels gives a blue color whose luminance and contrast are accentuated compared to the prior art or compared to the pixels located outside the window F. The metallic layer 102" present below the second yellow sub-pixel from the left of the window F and the adjacent magenta sub-pixel to its left, blocks the transmission of light from the rear face to the front face of the document. Thus, the yellow and magenta components are no longer present in the pixel viewed on the front face and the combination of the adjacent cyan and yellow sub-pixels gives a green color whose luminance and contrast are accentuated compared to the prior art or compared to the pixels located outside the window F. This is also accentuated by the presence of the metallic layer above the magenta sub-pixel located to the right of the window. The color rendering of Figures 5a and 5c is the same. [Fig.5d] shows a sectional view of the 1000” security document when illuminated from its front face. The front face of document 1000' is exposed to a light source and more particularly window F. The metal layer 102' present below the first yellow sub-pixel of the window F, starting from the left, increases the reflection of the yellow sub-pixel because the light can no longer pass through the yellow sub-pixel. The adjacent sub-pixel on the right lets the light pass (because the layer 102' is perforated under the magenta sub-pixel) and thus a predominance of the yellow color is observed compared to the other sub-pixels. Thus, the observed color is a yellow whose luminance and contrast are accentuated compared to the prior art or compared to the pixels located outside the window F. The metallic layer 102' present below the second yellow sub-pixel from the left of the window F and the adjacent magenta sub-pixel to its left, increases the reflection of these two pixels because light can no longer pass through these two sub-pixels. These two yellow and magenta sub-pixels being surrounded by blue sub-pixels under which the 102” layer is perforated, these two blue sub-pixels let the light pass. Thus, the yellow and magenta components have an increased reflectivity compared to the adjacent blue sub-pixels and thus, we observe a predominance of the red color (combination of yellow and magenta). Thus, the observed color is a red whose luminance and contrast are accentuated compared to the prior art or compared to the pixels located outside the window F. The metallic layer 102" present below the third magenta sub-pixel from the left of the window F, increases the reflection of this sub-pixel because the light can no longer pass through. This is accentuated by the fact that the layer 102” is perforated below the yellow sub-pixel adjacent to the left of the magenta sub-pixel. Thus, the observed color is a magenta whose luminance and contrast are accentuated compared to the prior art or compared to the pixels located outside the window F. The examples in Figures 5a to 5d illustrate that the perforated metal layer advantageously makes it possible to obtain modified colors and in particular increased contrast and brightness. Thus, this perforated metal layer makes it possible to broaden the color gamut obtained by the sub-pixel matrix in the absence of the perforated metal layer. Advantageously, it may be envisaged to represent in the window F, an image or information already contained in another part of the document 1000 or 1000'. Indeed, when the document 1000 (or 1000”) is an identity document, this document generally comprises, on a surface V of the document, an image representative of the face of the holder of the document. It may be desired to reproduce, in a window F of smaller dimension than the surface V, this image with a larger color gamut. The present disclosure can advantageously allow this reproduction. The presence of this portrait in the window F improves the security of the document by making it more difficult to falsify. In addition, as illustrated in figures Sa to Sd, the rendering of the colors being different in transmission or reflection of the light on the document, this falsification is made even more complex. It may also be desired to represent in this window F, an image or information already represented in one or more parts of the document, for example with a rotation of this information in the window F in relation to its orientation in the other part of the document. In some embodiments, the metal layer may be located above the pixel array in one or more windows of the document and below the pixel array in one or more windows of the document. This further enhances the security of the document by making it more complex to manufacture. In order to improve the adhesion of the metal layer with adjacent layers, and for example adjacent polycarbonate layers, the metal layer may be partially demetallized beforehand in order to promote the adhesion of the layers and make the document more resistant. A demetallization of around 2% of the metal layer may be sufficient to achieve this goal. Furthermore, it can be seen that the transparency of the protective layers 103 and 104 in the different embodiments illustrated above can allow a visualization of the information contained in the window(s) F on both sides of the document. As illustrated previously, it can be seen that the visual rendering can also be different depending on whether the document is observed from its front face or from its back face. The presence of transparent layers below and above the assembly formed by the pixel matrix and the metal layer allows this visual rendering. The presence of transparent layers on the other parts of the document or on all the other parts of the document is optional, at least on both sides.When the window includes a part, modified or not, of content reproduced on another part of the document, then it is necessary that this other part be visible and that the document therefore also includes a transparent layer at the level of this part so that this content is visible when observing at least from one of the two sides of the document. In [Fig.6], a top view of a first example of the colored sub-pixel matrix 101 is shown. Here, colored lines are aligned in groups of three colors, i.e. three lines. In [Fig.7], a top view of a second example of the colored sub-pixel matrix 101 is shown. Here, colored subpixels are arranged in a mosaic pattern, alternating cyan, magenta, and yellow subpixels in each row and column. Other examples of sub-pixel arrays are of course conceivable within the scope of the present disclosure. The arrangement examples of Figures 6 and 7 are given as an example of a representation of the arrangement of the subpixel matrix and can be used in the subpixel matrices shown in Figures 1 to 5.

Claims

Claims

1. Security document comprising a stack of layers comprising a matrix of colored sub-pixels (SB, SM, SJ), a metal layer adjacent to at least part of one face of the matrix of colored subpixels, in which the metal layer has perforations opposite sub-pixels of the matrix of colored subpixels.

2. Document according to claim 1 wherein said metal layer having perforations is located only in a first window of said document.

3. Document according to one of the preceding claims in which said metal layer is positioned above the subpixel matrix colorful.

4. Document according to one of the preceding claims in which said metal layer is positioned below the sub-matrix colored pixels.

5. Document according to one of claims 2 to 4 in which the vi- displayed in said window comprises at least part of an image viewed on a second window of said document, said second window being located on an area of ​​said document not including said perforated metal layer.

6. Document according to one of the preceding claims in which said metallic layer is previously partially demetallized from so as to adhere to the layer(s) between which it is inserted.

7. Document according to one of the preceding claims in which said perforated metal layer is perforated so that the image vi- displayed in the said first window presents a different visual rendering depending on whether the document is illuminated from the front or from the front back.

8. Method of manufacturing a security document in which one assembles a matrix of colored subpixels with a me- metal, adjacent to at least a portion of a face of the matrix of colored subpixels, the method further comprising forming per- drillings through said metallic layer opposite sub-pixels of the matrix of colored subpixels.

9. A manufacturing method according to claim 8 wherein said layer metallic is assembled only in one window of said document.

10. Manufacturing method according to one of claims 8 or 9 in which said metal layer is positioned above the sub-matrix colored pixels.

11. Manufacturing method according to one of claims 8 or 9 in which said metal layer is positioned below the matrix of colored subpixels.

12. Manufacturing method according to one of claims 8 to 11 in which said metallic layer is previously partially demetallized so as to adhere to the layer(s) in which it is inserted.

13. Manufacturing method according to one of claims 8 to 12 in which the formation of perforations is obtained by lasering the layer metallic.