METHOD FOR MANUFACTURING A SAFETY DEVICE WITH OPTICAL VARIABILITY, AND CORRESPONDING SAFETY DEVICE

Description

Technical Field

[0001] The present invention relates to the field of optical security devices, and more particularly concerns the manufacture of such a security device.

[0002] The invention applies non-exclusively to security and / or physical identity documents.

[0003] The term "identity document" refers to any document containing information (photograph, surname, first name, etc.) that allows the authorized bearer of the document to be identified more or less securely. This identity information appears physically on the body of the document so that it can be visually verified by a person or a control machine. In addition to the identity information visually accessible on the body of the identity document, it is possible to store identity information in a memory contained in the body of the identity document (in a chip for example), this information being electronically accessible if necessary by suitable means to verify the identity of the person concerned.

[0004] The identity document can therefore be a passport, an identity card, a driving license, a residence permit, etc. Prior art

[0005] As is known, a security and / or identity document may include an optical security device enabling verification of the authenticity of the document. Such an optical security device is difficult to reproduce using conventional technologies, and thus makes it possible to combat falsification of the security document.

[0006] More specifically, the security device may be optically variable, the visual rendering generated by the security device then varying depending on the position of the security device relative to the user. Such optically variable security devices provide an easy and rapid means of identification by the human eye, the optical variability being further able to be identified by a device comprising an optical sensor, such as a mobile terminal of the “smartphone” type.

[0007] There is now a need for a new security device that is more difficult to counterfeit and thus makes it possible to make the security document comprising the new security device more difficult to falsify. WO 2019 / 175514 describes the preamble of claim 1 or a document capable of generating a color image, comprising a set of pixels printed on a substrate and a lens array arranged opposite the set of pixels. Statement of the invention

[0008] The present invention relates to a manufacturing method as described in claim 1.

[0009] Since the optical rendering of the manufactured security device varies depending on the orientation of the device and is generated by means of two different parts of the device support, modified using different technologies (printing and laser engraving), the security device is more difficult to falsify.

[0010] In a particular embodiment, the method further comprises a step of adjusting the laser so that the Rayleigh length of the laser is less than or equal to the thickness of the optical separator.

[0011] In a particular embodiment, the thickness of the optical separator is greater than or equal to 100 micrometers.

[0012] In a particular embodiment, the opacification is carried out uniformly for all the pixels opposite which a region of the second part of the support is opacified, the opacification being carried out opposite at least one sub-part of the same sub-pixel of each of said pixels.

[0013] Thus, for each direction, the color of the rendering of the security device at the level of the first zone is uniform.

[0014] In a particular embodiment, the opacification is carried out with respect to the entirety of at least one sub-pixel of at least one pixel.

[0015] Opacification is thus simpler and faster, as the laser does not need to adapt to different shades of gray.

[0016] In a particular embodiment, the opacification is carried out so as to encode information, so that for at least one pixel of the first zone of the matrix: a region facing at least one sub-portion of the first sub-pixel is opacified to encode a first information, and a region facing at least one sub-portion of the second sub-pixel is opacified to encode a second information.

[0017] In a particular embodiment, the shape of the first zone is determined so as to graphically represent information visible to a user of the security device.

[0018] In a particular embodiment, each pixel of the matrix comprises three sub-pixels of different colors, the opacification being carried out so that, for each pixel opposite which a region of the second part of the support is opacified, said region masks: a first sub-pixel of said pixel when the security device is viewed from a first direction, a second sub-pixel of said pixel when the security device is viewed from a second direction, and a third sub-pixel of said pixel when the security device is viewed from a third direction, or a sub-pixel of the pixel following or preceding the pixel associated with the opacified region.

[0019] In a particular embodiment, the third part comprises one or more regions modified by means of a laser, each region being positioned opposite at least a part of at least one sub-pixel of an associated pixel, positioned in the second zone of the matrix, the modified regions of the third part being positioned as close as possible to the matrix.

[0020] In a particular embodiment, a laserizable layer receiving the printing of the sub-pixels forming the matrix comprises the third part, the laser being capable of modifying the third part in the thickness of said laserizable layer in line with said at least one sub-pixel, said associated modified region then being juxtaposed with said at least one sub-pixel or very close.

[0021] The security device is thus easily incorporated into a laser image, this incorporation not requiring additional manufacturing means.

[0022] In a particular embodiment, the third part is positioned on the first part.

[0023] The invention further relates to an optically variable security device, as described in claim 10.

[0024] The invention further relates to a security document comprising an optically variable security device as described above. Brief description of the drawings

[0025] Other characteristics and advantages of the present invention will emerge from the description given below, with reference to the appended drawings which illustrate an exemplary embodiment thereof without any limiting character. In the figures: [ Fig. 1 ] There figure 1 schematically represents a first example of a safety device that can be manufactured using the method of the figure 7 ; [ Fig. 2 ] There figure 2 schematically represents a second example of a safety device that can be manufactured according to the method of the figure 7 ; [ Fig. 3 ] There figure 3 schematically represents a third example of a safety device that can be manufactured according to the method of the figure 7 ; [ Fig. 4 ] There figure 4 is a top view of an example of a matrix that can be printed when implementing the method of the figure 7 ; [ Fig. 5 ] There figure 5 schematically represents a fourth example of a safety device which can be manufactured according to the method of the figure 7 ; [ Fig. 6 ] There figure 6 schematically represents a security document comprising a security device in accordance with an exemplary embodiment of the invention; [ Fig. 7 ] There figure 7 represents, in the form of a flowchart, the main steps of a manufacturing process in accordance with an exemplary embodiment of the invention; [ Fig. 8 ] There figure 8 represents, schematically, a first example of representation of a computer file which can be used during the implementation of the method of the figure 7 ; [ Fig. 9 ] There figure 9 represents, schematically, a second example of representation of a computer file which can be used when implementing the method of the figure 7 ; [ Fig. 10 ] There figure 10 represents, schematically, an example of a control screen for digital processing means capable of implementing part of the process of the figure 7 ; [ Fig. 11 ] There figure 11 schematically represents an example of implementation of the opacification step of the process of the figure 7 ; [ Fig. 12 ] There figure 12 schematically represents an example of the result of the opacification step of the process of the figure 7 ; [ Fig. 13 ] There figure 13 schematically represents an example of implementation of the step of modifying the process of the figure 7 ; [ Fig. 14 ] There figure 14 schematically represents an example of the result of the process modification step of the figure 7 ; [ Fig. 15A-15C ] THE figures 15A, 15B et 15C represent, schematically, an example of rendering of a security device manufactured during the implementation of the method of the figure 7 ; [ Fig. 16 ] There figure 16 schematically represents a fifth example of a safety device that can be manufactured according to the method of the figure 7 ; [ Fig. 17 ] There figure 17 schematically represents a sixth example of a safety device that can be manufactured according to the method of the figure 7 ; [ Fig. 18 ] There figure 18 represents three curves that can be used when implementing the process of the figure 7 . Description of the embodiments

[0026] The present invention relates to a security device 100 with optical variability, that is to say a security device 100 whose visual rendering varies according to the position of the security device 100 relative to the user of said security device 100 or relative to an optical sensor, and thus according to the viewing direction of the security device 100.

[0027] The security device 100 is thus capable of generating at least a first visual rendering when it is oriented in a first direction (and thus viewed in this first direction), and a second visual rendering when it is oriented in a second direction (and thus viewed in this second direction).

[0028] The security device 100 is level 1, the verification of the visual renderings generated by the security device 100 can be carried out with the naked eye. The verification of the visual renderings can further be carried out by a device comprising an optical sensor, such as a mobile terminal of the “smartphone” type.

[0029] THE figures 1, 2 , 3 , 5 , 16 et 17 show such safety devices 100, in accordance with exemplary embodiments. The examples of the figures 1, 2 , 3 , 16 And 17 are not claimed, but are useful for understanding the invention. The example of the figure 5 is an embodiment of the invention.

[0030] The security device 100 comprises a support 110 comprising a first portion 112, a second portion 114 and a transparent optical separator 116. The optical separator 116 separates the first portion 112 from the second portion 114. In other words, the optical separator 116 is positioned between the first portion 112 and the second portion 114.

[0031] A first face of the optical separator 116 is typically in contact (or is integral) with a first face of the second part 114. The first face of the optical separator 116 is thus typically fixed integrally to the first face of the second part 114, the fixing being for example carried out by lamination.

[0032] Furthermore, a second face of the optical splitter 116 may be in contact with the first face of the first part 112. The second face of the optical splitter 116 is thus typically fixedly attached to the first face of the first part 112 (see figures 1 has 3 , 5 And 16 ).

[0033] Alternatively, as shown in the figure 17 , the second face of the optical separator 116 may not be securely attached to the first face of the first part 112.

[0034] The security device 100 may further comprise an opaque or transparent layer 118 positioned against a second face of the second portion 114 (see figures 1 has 3 And 5 ) or against a second face of the first part 112 (see figures 16 And 17 ).

[0035] When the layer 118 is positioned against the second part 114, the second part 114 is then positioned between the optical separator 116 and the opaque layer 118. The second face of the second part 114 is typically fixed integrally to the layer 118, the fixing being for example carried out by lamination.

[0036] When the layer 118 is positioned against the first part 112, the first part 112 is then positioned between the optical separator 116 and the opaque layer 118. The second face of the first part 112 is typically fixed integrally to the layer 118, the fixing being for example carried out by lamination.

[0037] When the first part 112, the second part 114, the optical separator 116 and the opaque or transparent layer 118 are fixed together, the support 110 can form a single page of a security document such as a passport.

[0038] When the optical separator 116 is not securely attached to the first portion 112, a portion of the support 110 comprising the first portion 112 and the layer 118 may form a first page of a security document such as a passport, and a portion of the support 110 comprising the optical separator 116 and the second portion 114 may form a second page of this security document. The layer 118 is then typically transparent.

[0039] When layer 118 is opaque, this layer 118 is typically white in color.

[0040] The first part 112 and the optical separator 116 and / or the opaque or transparent layer 118 are typically made of a material insensitive to laser radiation, which is for example polycarbonate. Alternatively, the optical separator 116 is made of a material sensitive to laser radiation.

[0041] The second part 114 is made of a material sensitive to laser radiation, which may also be polycarbonate.

[0042] The thickness of the first part 112 is for example between 50 and 100 micrometers. In addition, the thickness of the second part 114 is typically 50 micrometers. The thickness h PC of the optical separator 116 is typically between 80 micrometers and 300 micrometers, and is for example 100 micrometers.

[0043] In addition, the first part 112, the second part 114 and / or the optical separator 116 may each take the form of a layer of the support 110, the support 110 then being a multilayer structure. Alternatively, the same layer may comprise the optical separator 116 and the second part 114, the layer then being made of a material sensitive to laser radiation.

[0044] The first portion 112 of the support 100 comprises a matrix 120 formed by printing. Alternatively, the matrix 120 forms the first portion 112, the matrix 120 then being directly printed on the optical separator 116, or on the opaque or transparent layer 118.

[0045] The matrix 120 comprises a plurality of pixels 122, each pixel 122 comprising at least two sub-pixels 123, 124, 125 of different colors, arranged in the same order for each pixel 122.

[0046] As shown for example by the figures 2 , 3 And 5 , each pixel 122 typically comprises three sub-pixels 123, 124, 125 of different colors, for example the primary colors red, green and blue or yellow, magenta and cyan. Alternatively, each pixel 122 may comprise four sub-pixels of different colors, for example yellow, magenta, cyan and white.

[0047] Furthermore, as shown in the figure 4 , each pixel 122 is typically square in shape and each sub-pixel 123, 124, 125 is rectangular in shape. Alternatively, the pixels 122 of the matrix 120 may take the shape of another geometric figure, such as a rectangle or a triangle (the sub-pixels 123, 124, 125 may then also take the shape of a triangle).

[0048] The matrix 120 can be partitioned into a first area 426 and a second area 428, each area 426, 428 then comprising a plurality of pixels 122 of the matrix 120 (see figures 4 And 5 ). Alternatively, as shown for example by the figures 1, 2 And 3 , the matrix 120 may only comprise the first area 426, the first area 426 comprising all of the pixels 122 of the matrix 120.

[0049] The shape of the first zone 426 may typically graphically represent, seen from above, information visible to the user of the security device 100. This information is typically personal data of the authorized bearer of a security and / or identity document incorporating the security device 100, or data relating to said document. The information is for example represented in the form of a string of alphanumeric characters, as shown for example in figure 8 , where the first area 426 represents the number “1982”. The color of the first area 426 depends on the positioning of the opacified regions 130 opposite the first area 426, as described in more detail below.

[0050] The matrix 120 may also comprise at least one positioning pattern 430 (see for example figure 4 ), allowing the laser to be positioned. Four positioning patterns 430 are for example used, one at each corner of the matrix 120. Each positioning pattern 430 is capable of being detected from an acquisition, by an optical sensor, of at least a portion of the matrix 120 comprising this positioning pattern 430.

[0051] The second part 114 of the support 110 comprises one or more regions 130 opacified by means of a laser, the regions 132 of the second part 114 not being opacified being transparent.

[0052] At least one opacified region 130 is positioned opposite at least one sub-part of at least one first sub-pixel 123, 124, 125 of at least one pixel 122 said to be associated with said opacified region 130, said pixel 122 being positioned in the first zone 126 of the matrix 120, so that said region 130 at least partially masks: the first sub-pixel 123, 124, 125 of said associated pixel 122 when the security device 100 is viewed in a first direction D1, and a second sub-pixel 123, 124, 125 of said associated pixel 122 when the security device 100 is viewed in a second direction D2.

[0053] Thus, each opacified region 130 is positioned opposite one or more sub-pixels of an associated pixel 122. All the pixels 122 of the first zone 426 can thus be associated with opacified regions 130.

[0054] More specifically, each opacified region 130 may be positioned opposite a portion of a sub-pixel 123, 124, 125 or the entire sub-pixel 123, 124, 125, and possibly opposite a portion or the entirety of one or more other sub-pixels 123, 124, 125 of the same pixel 122.

[0055] By “positioned opposite” is meant “positioned under or on” when the security device 100 is seen from above, i.e. when the security device 100 is viewed perpendicular to the plane formed by the surface of the matrix 120. Furthermore, by “pixel associated with the opacified region”, is meant that the opacified region is positioned opposite a sub-pixel of this pixel, when the security device 100 is seen from above.

[0056] Each opacified region 130 is thus positioned in the support 110 at the intersection of the projection of the first sub-pixel 123 along the first direction D1 and the projection of the second sub-pixel 124 along the second direction D2.

[0057] The first subpixel 123 and the second subpixel 124 are typically adjacent subpixels.

[0058] Furthermore, the first direction D1 is typically the direction perpendicular to the plane formed by the surface of the second part 114 and is therefore associated with a first viewing angle θ 0 of 90 degrees relative to the plane formed by the surface of the second part 114.

[0059] The second direction D2 is associated with a second viewing angle Iθ air I relative to the normal to the plane formed by the surface of the second part 114.

[0060] Each opacified region 130 can further mask, at least in part and in a third direction D3, a third sub-pixel 123, 124, 125 of the pixel 122 associated with the opacified region 130, or a sub-pixel of the pixel 122 following or preceding the pixel 122 associated with the opacified region 130.

[0061] Thus, when each pixel 122 of the matrix 130 comprises three sub-pixels 123, 124, 125 of different colors, the opacification can be carried out so that, for each pixel 122 opposite which a region 130 of the second part 114 of the support 110 is opacified, said region 130 masks: the first sub-pixel of said pixel 122 when the security device 100 is viewed in a first direction D1, a second sub-pixel of said pixel 122 when the security device 100 is viewed in a second direction D2, and a third sub-pixel of said pixel 122 when the security device 100 is viewed in a third direction D3, or a sub-pixel of the pixel 122 following or preceding the pixel 122 associated with the opacified region 130.

[0062] The terms “first”, “second” and “third” of the expressions “first sub-pixel”, “second sub-pixel” and “third sub-pixel” are introduced to distinguish the sub-pixels 123, 124, 125 within the same pixel 122. Also, the expression “first sub-pixel” does not designate a sub-pixel positioned at a particular location of the pixel 122 (and likewise for the expressions “second sub-pixel” and “third sub-pixel”).

[0063] Similarly, the terms "first," "second," and "third" in the expressions "first direction," "second direction," and "third direction" are introduced to distinguish different directions of viewing.

[0064] For example, the safety device 100 of the figure 1 comprises a plurality of opacified regions 130, each opacified region 130 being positioned under the right sub-pixel 124 of each associated pixel 122, the second direction D2 thus being oriented at a second negative air angle -θ relative to the normal to the surface of the support 110 of the security device 100. However, one or more of these opacified regions 130 (for example all) could be positioned under the left sub-pixel 123 of the associated pixels 122, the second direction D2 then being oriented at a second positive air angle θ relative to the normal to the surface of the support 110 of the security device 100.

[0065] Furthermore, each opaque region 130 of the security device 100 of the figure 2 is positioned opposite the left sub-pixel 123 and the right sub-pixel 125 of the associated pixel 122, and each opaque region 130 of the security device 100 of the figure 3 is positioned opposite the center sub-pixel 124 and the right sub-pixel 125 of the associated pixel 122. However, for each of these security devices 100, other positions of opacified regions 130 could be considered, in order to display different colors according to the different viewing directions.

[0066] Furthermore, in order to obtain the desired optical variability effect, a transparent region 132 of the second part 114 of the support 110 is positioned opposite at least one part of at least one sub-pixel 123, 124, 125 of said pixel 122 associated with said opacified region 130. It is then said that the transparent region 132 is associated with said pixel 122.

[0067] Also, in order to obtain the desired optical variability effect at a given pixel 122, at least one sub-pixel of said pixel 122 must be positioned opposite an associated opacified region 130 and at least one other sub-pixel of said pixel 122 must be positioned opposite an associated transparent region 132.

[0068] The transparent region 132 of the second part 114 of the support 110 can be positioned so as to let light pass at the first sub-pixel 123 when the security device 100 is viewed in the second direction D2, and so as to let light pass at the sub-pixel following or preceding the first sub-pixel when the security device 100 is viewed in the first direction D1, said following or preceding sub-pixel being a sub-pixel of the same pixel as the first sub-pixel, or a sub-pixel of the following or preceding pixel.

[0069] The transparent region 132 may further be positioned so as to allow light to pass through at the sub-pixel following or preceding the first sub-pixel when the security device 100 is viewed in the third direction D3, said sub-pixel being a sub-pixel of the same pixel as the first sub-pixel, or a sub-pixel of the following or preceding pixel.

[0070] When the layer 118 is opaque, in order to obtain the desired optical variability effect, the assembly comprising the first part 112, the optical separator 116 and the second part 114 is positioned between the user's eye (or the optical sensor) and the opaque layer 118.

[0071] In such a configuration, each transparent region 132 allows light to pass through, so that it is reflected on the opaque layer 118, while each opacified region 130 blocks (or absorbs) the light which is thus not reflected by the opaque layer 118. Each opacified region 130 therefore creates a shadow at the level of at least a part of at least one sub-pixel of the associated pixel 122, according to each viewing direction. This is then referred to as reflective reading.

[0072] When the layer 118 is transparent, in order to obtain the desired optical variability effect, the assembly comprising the first portion 112, the optical separator 116 and the second portion 114 is positioned between the user's eye (or the optical sensor) and the transparent layer 118, or the transparent layer 118 may be positioned between the user's eye (or the optical sensor) and the assembly comprising the first portion 112, the optical separator 116 and the second portion 114. When the first portion 112 is positioned between the user's eye and the second portion 114, each opacified region 130 generates a shadow on at least a portion of at least one sub-pixel of the associated pixel 122, while when the second portion 114 is positioned between the user's eye and the first portion 112, at least a portion of at least one sub-pixel of the associated pixel is filtered by the region 130 opaque. We then speak of transmission reading.

[0073] As visible on the figures 1 has 3 , 5 , 16 And 17 , the position of the opacified region 130 may be periodic, each opacified region 130 being positioned opposite the same sub-pixel(s) of each pixel 122.

[0074] The opacification is then carried out uniformly for all of the pixels 122 opposite which a region 130 of the second part 114 of the support 110 is opacified, the opacification being carried out opposite at least one sub-part of the same sub-pixel 123, 124, 125 of each of said pixels 122.

[0075] The sub-pixels 123, 124, 125 of each pixel 122 of the matrix 120 being arranged in the same order, for each direction D1, D2, D3, the color displayed at the level of the first zone 426 of the matrix 120 is then uniform. The color variation between the different directions D1, D2, D3 is then significant and thus very visible.

[0076] For example, each transparent region 132 of the security device 100 of the figure 1 lets light pass at the left sub-pixel 123 of the associated pixel 122 when the security device 100 is viewed in the first direction D1, and lets light pass at the right sub-pixel 124 of the pixel 122 preceding the associated pixel 122 when the security device 100 is viewed in the second direction D2.

[0077] Furthermore, each opaque region 130 of the security device 100 of the figure 1 masks the right sub-pixel 124 of the associated pixel 122 when the security device 100 is viewed in the first direction D1, and masks the left sub-pixel 123 of the associated pixel 122 when the security device 100 is viewed in the second direction D2.

[0078] Thus, when this security device 100 is viewed in the first direction D1, the color displayed by the security device 100 is that of the left sub-pixels 123 of the pixels 122 of the matrix 120 and, when the security device 100 is viewed in the second direction D2, the color displayed by the security device 100 is that of the right sub-pixels 124 of the pixels 122 of the matrix 120.

[0079] In addition, each opaque region 130 of the security device 100 of the figure 2 is positioned opposite the left sub-pixel 123 and the right sub-pixel 125 of the associated pixel 122, the transparent region 132 being positioned opposite the middle sub-pixel 124. The color displayed in the first direction D1 is then the color of the middle sub-pixels 124 of the pixels 122 of the matrix 120, the color displayed in the second direction D2 is the color of the left sub-pixels 122, and the color displayed in the third direction D3 is the color of the right sub-pixels 125.

[0080] In addition, each opaque region 130 of the security device 100 of the figure 3 is positioned opposite the middle sub-pixel 124 and the right sub-pixel 125 of the associated pixel 122. The color displayed in the first direction D1 is then the color of the left sub-pixels 123 of the pixels 122 of the matrix 120, the color displayed in the second direction D2 is the color of the right sub-pixels 125, and the color displayed in the third orientation O3 is the color of the middle sub-pixels 124.

[0081] The opacification can be carried out so as to encode information, so that for at least one pixel 122 of the first zone 126 of the matrix 120: a region 130 facing at least one sub-part of the first sub-pixel is opacified to code a first piece of information, and a region 130 facing at least one sub-part of the second sub-pixel is opacified to code a second piece of information.

[0082] For example, a region 130 positioned opposite the first sub-pixel of a pixel 122 may encode a first information that the authorized bearer of a security document comprising the security device 100 is a male, while a region 130 positioned opposite the second sub-pixel of a pixel 122 may encode a second information that the authorized bearer of the security document is a female.

[0083] As shown in the figure 5 , the matrix 120 may be partitioned into a first zone 426 and a second zone 428. The support 110 of the security device 100 may then further comprise a third portion 540. The third portion 540 is typically positioned against the first portion 112, such that the first portion 112 is positioned between the third portion 540 and the optical separator 116. The third portion 540 is made of a material sensitive to laser radiation, and is typically made of polycarbonate. The third portion 540 is typically a layer of the support 110. The thickness of the third portion 540 is less than or equal to 100 micrometers, in order to limit the effects of optical variation between the matrix 120 and this third portion 540 during laser engraving.

[0084] The third portion 540 comprises one or more regions 542 modified by means of a laser, each region 542 being positioned opposite at least a portion of at least one sub-pixel 123, 124, 125 of an associated pixel 122, positioned in the second zone 428 of the matrix 120.

[0085] The modified regions 542 of the third part 540 being positioned closer to the matrix 120 than the opacified regions of the second part 114, the optical effect is different. The modified regions 542 of the third part 540 make it possible to obtain the final color of the pixels 122 associated with the second zone 428 of the matrix 120, this final color remaining the same regardless of the viewing direction of the security device 100.

[0086] For a given pixel 122, the final color is the color of the subpixel of that pixel 122 not facing a modified region 542, or is the combination of the colors of the subpixels not facing a modified region 542.

[0087] The third part 540 of the support 110 thus modified and the second zone 428 of the matrix 120 form a graphic representation.

[0088] The modification made by means of the laser is an opacification or an ablation.

[0089] The third part 540 may thus comprise one or more opacified regions 542, resulting from carbonization of the third part 540 by means of a laser, the regions 544 of the second part 114 not being opacified being transparent.

[0090] At least one opacified region 542 is positioned opposite at least one sub-part of at least one sub-pixel 123, 124, 125 of at least one pixel 122 associated with said opacified region 542, said pixel 122 being positioned in the second zone 428 of the matrix 120.

[0091] When the modification is an ablation, the third part 540 comprises the first part 112 and therefore the matrix 120. Each region 542 removed is then at least a part of at least one sub-pixel of the associated pixel 122.

[0092] The security device 100 is typically integrated into a security and / or identity document 600 such as a passport, an identity card, a driver's license, etc. (see figure 6 ).

[0093] The support 110 can thus be a card body or one or more pages of a security document, for example such as a passport.

[0094] There figure 7 represents a method of manufacturing an optically variable security device, such as the security devices 100 described with reference to figures 1 has 3 , 5 , 16 And 17 , the method being in accordance with an exemplary embodiment of the invention. The manufacturing method is typically implemented by a manufacturing system comprising digital data processing means, printing means and laserizing means, the laserizing means comprising at least one laser and possibly comprising an optical sensor. The laser beam of the laser is typically diverging or collimated.

[0095] The data processing means typically take the form of a computer, executing a computer program stored in a computer-readable information medium (or memory).

[0096] The method may comprise a step S200 of obtaining the support 110 of the security device 100. The support 110 is typically manufactured during this step S200, this manufacturing comprising printing the matrix 120 forming the first part 112 of the support 110, on the optical separator 116 or the opaque or transparent layer 118.

[0097] The matrix 120 is more precisely printed by the printing means of the manufacturing system, the printing typically being offset printing, digital printing or inkjet printing, or a flexographic, heliographic or pad printing technique. In addition, the ink used is typically an ink transparent to infrared radiation, the ink thus not reacting to the laser rays used in step S230 described below.

[0098] One or more positioning patterns 150 may further be formed by printing during step S200.

[0099] When the support 110 is a multi-layer structure, the support 110 can be manufactured by printing the matrix on the optical separator 116 or the opaque or transparent layer 118, then by laminating the different layers of the support 110, i.e. the layer forming the first part 112, the layer forming the second part 114 and / or the optical separator 116, as well as possibly the opaque layer 118 and / or the layer forming the third part 540.

[0100] In a step S210, the shape of the first zone 426 can be determined, as well as possibly the shape of the second zone 428.

[0101] The first zone 426 represents information which may be personal data of the authorized bearer of the security and / or identity document incorporating the security device 100, or data relating to said document. The first zone may thus take the form of a string of alphanumeric characters.

[0102] Thus, the shape of the first zone 426 may vary from one security device 100 to another.

[0103] This step S210 is typically implemented via digital data processing means, the shape of the first zone 426 and of the possible second zone 428 being able to be recorded in a computer file. figure 8 shows an example of a representation of such a computer file 800, in which the first field 426 represents the number “1982” and thus takes the form of this number.

[0104] Step S210 may further comprise a step of determining the graphic representation RG to be formed at the second zone 428. This graphic representation RG typically takes the form of a photograph of the face of the authorized bearer of the document 600 incorporating the security device 100.

[0105] The determination of the RG graphical representation is typically carried out via digital data processing means, which record the RG graphical representation in a computer file. figure 9 shows an example of a representation of such a computer file 900, in which the graphic representation RG takes the form of a photograph. As seen in this figure 9 , the RG graphic representation does not encroach on the first zone 428.

[0106] In a step S220, at least a part of the matrix 120 is acquired, by means of the optical sensor of the laserization means, this part of the matrix 120 comprising the positioning pattern 430.

[0107] The positioning pattern 430 is then detected by the digital data processing means and then used to position the laser and possibly to size the first zone 426 and / or the second zone 428.

[0108] More precisely, as shown in the figure 10 which represents a control screen 1000 of the digital processing means, the first zone 426 of the matrix 120 is virtually positioned on the matrix 120 according to the positioning patterns 430 detected.

[0109] The acquisition of at least a portion of the matrix 120 makes it possible in particular, in step S230 described below, to opacify (and therefore position) the regions 130 precisely relative to the matrix 120. This acquisition is particularly useful when the opacification step S230 is carried out after the lamination of step S200, this lamination leading to a deformation of the assembled layers.

[0110] Step S220 may not be implemented in order to reduce the manufacturing costs of the safety device 100.

[0111] In a step S230, at least one region 130 of the second part 114 of the support is opacified by means of the laser. As already described with reference to figures 1 has 3 , 5 , 16 And 17 , said at least one opacified region 130 is positioned opposite at least one sub-part of at least one first sub-pixel of a pixel 122 associated with said region 130, said pixel 122 being positioned in the first zone 426 of the matrix 120, so that said region 130 at least partially masks: a first sub-pixel of said pixel 122 when the security device 100 is viewed in the first direction D1, and a second sub-pixel of said pixel 122 when the security device 100 is viewed in a second direction D2.

[0112] The laser can thus opacify a region 130 opposite each pixel 122 of the first zone 426.

[0113] When the optical separator 116 and the second part 114 are made of a material sensitive to laser radiation, the laser used is typically diverging. Step S230 can then be a step of adjusting the laser so that the Rayleigh length of the laser is less than or equal to the thickness h PC of the optical separator 116, so that the laser can opacify regions 130 in the second part 114 of the support 110.

[0114] When the same layer comprises the optical separator 116 and the second part 114, the distinction between the optical separator 116 and the second part 114 is created by the opacification of the regions 130.

[0115] The Rayleigh length is calculated using the following formula: Z r = πω 0 2 λ in which Z r is the Rayleigh length, ω 0 is the narrowing of the laser beam (called “waist”, in Anglo-Saxon terminology), and λ is the engraving wavelength.

[0116] Alternatively, when the optical separator 116 is made of a material insensitive to laser radiation while the second part is made of a material sensitive to laser radiation, the laser beam may be diverging or collimated.

[0117] The thickness h PC of the optical separator 116 is determined (typically in step S200) so that each opacified region 130 is positioned at the intersection of the projection of the first sub-pixel of the associated pixel 122 along the first direction D1 and the projection of the second sub-pixel of the associated pixel 122 along the second direction D2.

[0118] More precisely, the angle θ PC in the optical splitter 116 relative to the normal to the surface of the support 110 for which a subpixel can be observed through a transparent region 132 can be determined according to the following formula (see figure 16 ) : tan θ PC = w color , n h PC where w color,n is the width of a subpixel and h PC is the thickness of the optical separator 116.

[0119] Furthermore, the width p color of a pixel 122 can be determined according to the following formula: p color = n . w color , n where n is the number of subpixels of pixel 122.

[0120] When the position of the opacified regions 130 is periodic, the laser period p of the opacified regions (which is equal to the width of an opacified region 130 and an adjacent transparent region 132) is typically equal to the width of a pixel 122: p color = p laser

[0121] The viewing angle θ air relative to the normal to the surface of the support 110, for which a sub-pixel can be observed through a transparent region 132 (which is therefore the angle θ air of the viewing direction) can thus be determined from the Snell-Descartes law, and therefore from the following formula: θ air = sin − 1 n PC n air sin θ PC where n air is the refractive index of air and n PC is the refractive index of the optical splitter material 116.

[0122] The viewing angle θ can therefore be determined using the following formula: θ air = sin − 1 n PC n air sin tan − 1 w color , n h PC .

[0123] The height h PC of the optical separator 116 can thus be determined as a function of the refractive index of air n air , the refractive index of the material of the optical separator n PC , the width of a sub-pixel w color,n , and the viewing angle θ air.

[0124] When the position of the opacified regions 130 is periodic, the laser period p of the opacified regions may not be equal to the width of a pixel 122. The color viewed according to the viewing angle θ is then not homogeneous, which typically generates a Moiré effect. The visual rendering is then that of a rainbow moving according to the viewing direction.

[0125] There figure 18 represents three curves showing the variation of the viewing angle θ air as a function of the width of a sub-pixel w color,n , for different values ​​of height h PC of the optical separator 116.

[0126] More precisely, the first curve 190 represents the variation for a height h PC of 80 micrometers, the second curve 192 represents the variation for a height h PC of 150 micrometers, and the third curve 194 represents the variation for a height h PC of 300 micrometers.

[0127] Such curves can be used to determine the values ​​of the height h PC , the viewing angle θ air and the width of a sub-pixel w color,n allowing the desired optical variability effect to be obtained, while respecting the constraints linked to the security devices 100.

[0128] For example, the viewing angle θ is typically between 20 and 40 degrees and the width of a subpixel w color,n is then typically between 30 and 70 micrometers so that the color change is clearly visible. Also, in this example, only the values ​​of the curves 190, 192 and 192 lying in the Z zone can be considered.

[0129] The height h PC of the optical separator 116 is thus typically between 80 micrometers and 300 micrometers when the width of a sub-pixel w color,n is between 30 micrometers and 70 micrometers and the viewing angle θ is between 20 degrees and 40 degrees.

[0130] As shown in the figure 11 ,during the opacification step S230, the support 110 can be positioned on a base 1111 so that the second part 114 is positioned between the laser L and the first part 112 of the support 110. The laser L is then adjusted according to this positioning.

[0131] There figure 12 shows an example of the result of the opacification step S230, when the first zone 426 takes the form of the number “1982”.

[0132] When the support 110 comprises a third part 540, the method may further comprise a step S240 in which the third part 540 of the support 110 is modified by lasering, opposite at least one part of at least one sub-pixel of at least one pixel 122 positioned in the second zone 428 of the matrix 120, this modification making it possible to obtain the final and fixed color of said at least one pixel 122, the third part 540 of the support 110 thus modified and the second zone 428 of the matrix 120 forming the graphic representation, determined in step S210.

[0133] The laser used in modification step S240 is according to the invention the same laser as that used in opacification step S230. As shown in figure 13 , the support 110 can then be positioned on the base 1111 so that the third part 540 of the support 110 is positioned between the laser and the first part 112 of the support 110.

[0134] Alternatively, not claimed, the laser used in step S240 may be a different laser than the laser used in step S230.

[0135] The modification is for example an opacification of the third part 540, opposite said at least one part of at least one sub-pixel, carried out by means of the laser. For example, the laser punctually carbonizes the third part 540 so as to form a series of points opposite said at least one part of at least one sub-pixel in the third part 540 (i.e. between the two external faces of the third part 540), for example two or four points.

[0136] Carbonizing the third portion 540 opposite at least a portion of a sub-pixel of a pixel 122 generates a gray level at this sub-pixel, which makes it possible to obtain the final and fixed color of the pixel 122.

[0137] The data processing means are in fact capable of guiding the laser so that it carbonizes the third part 540 in order to obtain the final color of each pixel 122 making it possible to form the graphic representation of the second zone 428.

[0138] There figure 14 is a sectional view of an example result of modification step S240 when performed after modification step S230.

[0139] THE figures 15A, 15B et 15C show an example of the result of the process when files 800 and 900 of the figures 8 et 9 are used. More precisely, the figure 15A shows the security device 100 seen according to a first viewing direction, the figure 15B shows the security device 100 seen from a second viewing direction, the figure 15Cshows the security device 100 seen from a third viewing direction. As seen in these figures, the colors of the graphic representation of the second zone 428 are fixed regardless of the viewing direction. The information represented by the first zone 426 varies depending on each viewing direction.

[0140] The modification may alternatively be an erasure by ablation of said at least one part of at least one sub-pixel, carried out by means of the laser.

[0141] The security device 100 can be positioned in a security and / or identity document 600. Steps S310, S220, S230 and possibly step S210 and / or step S240 can be implemented during a personalization phase of the security and / or identity document 600.

Claims

1. Process for manufacturing an optically variable security device (100), said security device (100) comprising a carrier (110), said process comprising the following steps: - printing an array (120) forming a first part (112) of the carrier (110), said array (120) comprising a plurality of pixels (122), each pixel (122) comprising at least two sub-pixels (123, 124, 125) of different colours, - opacification (S230) of at least one region (130) of a second part (114) of the carrier (110) by means of a laser, said second part (114) being separated from the first part (112) by a transparent optical separator (116), said at least one opacified region (130) being positioned facing at least one sub-part of at least a first sub-pixel (123, 124, 125) of a pixel (122) associated with said opacified region (130), said pixel (122) being positioned in a first zone (426) of the array (120), so that said opacified region (130) masks at least in part: - the first sub-pixel (123, 124, 125) of said pixel (122) when the security device (100) is viewed in a first direction (D1), and - a second sub-pixel (123, 124, 125) of said pixel (122) when the security device (100) is viewed in a second direction (D2), the process further comprising modification of a third part (540) of the carrier (110) through application of the laser, facing at least one part of at least one sub-pixel (123, 124, 125) of at least one pixel (122) positioned in a second zone (428) of the array (120), said modification making it possible to obtain the final colour of said at least one pixel (122), the third part (540) of the carrier (110) thus modified and the second zone (428) of the array (120) forming a graphical representation, characterized in that: - the first part (112) of the carrier (110) is positioned between the second part (114) of the carrier (110) and the third part (540) of the carrier (110), - the opacification of the second part (114) of the carrier (110) and the modification of the third part (540) of the carrier (110) are carried out using the same laser, - during the opacification, the second part (114) of the carrier (110) is positioned between the laser and the first part (112) of the carrier (110), and - during the modification, the third part (540) of the carrier (110) is positioned between the laser and the first part (112) of the carrier (110).

2. Manufacturing process according to Claim 1, further comprising a step of adjustment of the laser so that the Rayleigh length of the laser is less than or equal to the thickness (hPC) of the optical separator (116).

3. Manufacturing process according to Claim 1 or 2, wherein the thickness (hPC) of the optical separator (116) is greater than or equal to 100 microns.

4. Manufacturing process according to any one of Claims 1 to 3, wherein the opacification is carried out uniformly for all the pixels (122) facing which a region (130) of the second part (114) of the carrier (110) is opacified, the opacification being carried out facing at least one sub-part of the same sub-pixel (123, 124, 125) of each of said pixels (122).

5. Manufacturing process according to any one of Claims 1 to 4, wherein the opacification is carried out facing the entirety of at least one sub-pixel (123, 124, 125) of at least one pixel (122).

6. Manufacturing process according to any one of Claims 1 to 5, wherein the opacification is carried out so as to encode information, so that, for at least one pixel (122) of the first zone (426) of the array (120): - a region (130) facing at least one sub-part of the first sub-pixel (123, 124, 125) is opacified to encode a first piece of information, and - a region (130) facing at least one sub-part of the second sub-pixel (123, 124, 125) is opacified to encode a second piece of information.

7. Manufacturing process according to any one of Claims 1 to 6, wherein the first zone (426) is determined so as to graphically represent a piece of information visible to a user of the security device (100).

8. Manufacturing process according to any one of Claims 1 to 7, wherein each pixel (122) of the array (120) comprises three sub-pixels (123, 124, 125) of different colours, the opacification being carried out so that, for each pixel (122) facing which a region (130) of the second part (114) of the carrier (110) is opacified, said region (130) masks: - a first sub-pixel (123, 124, 125) of said pixel (122) when the security device (100) is viewed in a first direction (D1), - a second sub-pixel (123, 124, 125) of said pixel (122) when the security device (100) is viewed in a second direction (D2), and - a third sub-pixel (123, 124, 125) of said pixel (122) when the security device (100) is viewed in a third direction (D3), or a sub-pixel (123, 124, 125) of the pixel (122) following or preceding the pixel (122) associated with the opacified region (130).

9. Manufacturing process according to Claim 1, wherein the third part (540) is positioned on the first part (112) .

10. Optically variable security device (100) directly obtained by the manufacturing process according to any one of Claims 1 to 9.

11. Security document (600) comprising an optically variable security device (100) according to Claim 10.