This application is a U.S. National Stage application of International Patent Appl. No. PCT/FR2012/000081 filed Mar. 8, 2012, which claims priority to French Application Ser. No. 11/00713 filed Mar. 10, 2011, the entire disclosures of which are hereby incorporated by reference in their entireties.
The subject of the present invention is a method for forming a back-lit colour laser image in an identity document carrying a back-lit colour laser image, and a backlighting system. It finds applications in particular for identity cards, credit cards, passports, driving licences, secure entry badges, etc.
Colour laser images composed of sub-pixels in the primary additive colours, red, green and blue, abbreviated in the remainder hereof to RGB, require either a device with high reflective yield as described in patent application FR 11/00578 filed on Feb. 28, 2011 or back lighting as used for Liquid Crystal Displays (LCDs). LCD screens are composed of a matrix of RGB pixels behind which there lies a block of liquid crystal cells and finally a back light which illuminates this assembly from behind causing the colour images to appear.
The aforementioned patent application describes the personalisation of a colour laser image formed of sub-pixels (R,G,B) printed underneath a protective layer, the said layer is then hot welded under pressure onto the body of an identity document. This hot welding under pressure of the protective layer is known in the trade as “lamination”.
A laser beam through the transparent protective sheet via carbonization produces dark, non-reflective surfaces in this transparent protective sheet which partly or wholly mask each sub-pixel (R,G,B) thereby forming the grey levels of a personalised colour laser image of high quality. The transparent protective sheet is commonly called “laserable” since it is sensitive to laser radiation.
Although of advantage in some respects, these colour laser images, depending on the environment in which they are observed, may require illumination to reinforce the luminosity of the image.
It is the objective of the present invention to overcome this disadvantage by proposing a method for producing an identity document comprising a personalised colour laser image which is back-lit.
This objective of the invention is achieved by means of a transparent identity document body through which a light flow passes which back lights the personalised colour laser image.
More specifically, the subject of the invention is a method for forming a back-lit personalised colour laser image comprising sub-pixels in the additive primary colours red green and blue. These sub-pixels are protected by a transparent laserable sheet. A laser beam via carbonization above each sub-pixel (R,G,B) causes the grey levels of a personalised colour laser image to appear in the transparent laserable protective sheet. The body of the document is transparent and a light flow passes through it which back lights the personalised colour laser image perpendicular to its plane.
The front side of the identity document comprises a laserable protective sheet which protects the sub-pixels (R,G,B) and the decorative patterns and anti-counterfeit systems. The reverse side carries decorative patterns and an anti-counterfeit system also protected by a transparent sheet laminated on the reverse side of the identity document.
According to a first embodiment of the invention, the light flow enters perpendicular to the plane of the document via the reverse side of the document through an opening made in the decorative patterns and anti-counterfeit systems.
According to one variant of the invention, the reverse side is fully covered by decorative patterns or anti-counterfeit systems. On one surface substantially equal to the surface of the personalised image on the front side of the identity document, and opposite the latter on the reverse side, the decorative patterns and anti-counterfeit system are pierced with tiny holes that are uniformly distributed and allow the passing of a light flow from a source located on the back of the identity document the flow passing through the document perpendicular the plane thereof. This light flow illuminates the personalised colour laser image from behind. The decorative patterns, anti-counterfeit systems and tiny holes are coated with a protective layer laminated on the reverse side of the identity document.
According to another embodiment of the invention, the light enters via least one side of the identity document through its thickness. Diffracting elements located underneath the personalised colour laser image scatter and send the light to behind this image passing through it perpendicular to its plane. Reflective means located on the reverse side of the identity document enhance the intensity of the light sent through the personalised laser image. The identity document is covered with decorative patterns and anti-counterfeit systems on its two sides.
The invention also concerns an identity document comprising a colour laser image back-lit by implementing the above method. This identity document comprises a sheet of laserable material acting as protective layer, this sheet being at least partly carbonized by laser radiation, sub-pixels (R,G,B) printed between the laserable sheet and a transparent document substrate, these sub-pixels (R,G,B) forming an image back-lit by a light flow passing perpendicularly through the image perpendicular to the plane of the document.
According to particular embodiments:
Finally the invention concerns an edge back lighting system capable of illuminating an identity document as previously described. It comprises a planar base on which the identity document is laid flat, at least one of its sides is placed in contact with at least one light concentrator which captures the light of a light source, and concentrates this light in the thickness of the identity document.
The invention will become better apparent after the following description given for explanatory purposes and in no way limiting. This description refers to the appended drawings in which:
At a second step a laser beam (6) via carbonization generates the grey levels (7) in the laserable sheet (2) above each sub-pixel (R,G,B), thereby forming the grey levels of a personalised colour laser image. This image is seen by the observer (8) by reflection of ambient light on the personalised colour laser image (3) through the laserable protective sheet (2).
On the reverse side (5) of the document, decorative patterns and anti-counterfeit systems (4) are printed except on the surface (22) opposite the personalised colour laser image. The elements of the reverse side of the identity document are protected by a transparent protective sheet (9) laminated on this reverse side. A flow of light (21) originating either from an artificial source or from ambient light passes through the back transparent protective sheet (9), the transparent body of the identity document (11) via the opening (22) perpendicular to its plane, and passes from behind through the personalised colour image and the protective sheet (2). The personalised colour laser image via transparency therefore appears to the observer (8) to be efficiently illuminated from behind.
These tiny holes do not deteriorate the quality of the decorative patterns or anti-counterfeit systems since they are hardly visible. They have a diameter of between 5 μm and 500 μm. This light, passing through these holes, illuminates the personalised colour laser image from behind. It is seen by the observer (8) via transparency with strong luminosity. All the elements of the reverse side (5) of the identity document are protected by a transparent protective sheet (9) laminated on the reverse side of the identity document.
On the front side (12) of the body (11) of the identity document there are elements (43) diffracting the light circulating in the thickness of the body of the document (11), and sending it back perpendicularly in the direction of the observer (8) through the personalised colour laser image (3). These diffracting elements (43), known to persons skilled in the art for LCD screens in particular, can be micro-cavities for example formed on the surface of the body (11) of the identity document. To reinforce the intensity of the diffracted light, reflective means (44) are located on the reverse side of the body of the document. These means may be a reflective varnish or a reflective metal foil. These means are covered by the decorative and anti-counterfeit elements (4), the whole being protected by the protective sheet (9) laminated on the reverse side (5) of the identity document.
Number | Date | Country | Kind |
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11/00713 | Mar 2011 | FR | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/FR2012/000081 | 3/8/2012 | WO | 00 | 9/9/2013 |
Publishing Document | Publishing Date | Country | Kind |
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WO2012/120207 | 9/13/2012 | WO | A |
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Entry |
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International Search Report and Written Opinion dated Jun. 12, 2012 for International Application No. PCT/FR2012/000081 filed Mar. 8, 2012, pp. 1-10. |
Number | Date | Country | |
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20130341900 A1 | Dec 2013 | US |