FR2972388A1 - Method for producing substrate for laser color image of identity document, involves forming smooth surfaces on face of laserable transparent protective sheet by hot-pressing, and enclosing rough surfaces over face of protective sheet - Google Patents

Abstract

The method involves forming smooth surfaces on which arrays of red, green and blue sub-pixels (R, G, B) are printed, on a face (2) of a laserable transparent protective sheet (1) by hot-pressing, where the face is laminated on a body of an identity document (3) and the sub-pixels are printed on a reflecting varnish layer. Rough surfaces laminated on the body of the identity document, are enclosed over the face of the protective sheet. An independent claim is also included for a document.

Description

METHOD FOR PRODUCING A LASER COLOR IMAGE SUBSTRATE AND IDENTITY DOCUMENT USING THE SAME

DESCRIPTION FIELD OF APPLICATION OF THE INVENTION The object of the present invention is a method for producing a substrate for a color laser image, and an identity document implementing this method. It finds applications especially in identity documents, credit cards, passports, driving licenses, secure entry badges, etc.

State of the Prior Art: Identity documents with a high level of security, consist of a document body, on which various motifs (security reasons, decorations, etc.) are printed by standard methods known to the skilled in the art. A sheet of material sensitive to laser radiation that is to say which darkens by carbonization under the influence of a laser beam which will be called thereafter sheet of material "lasérisable" is welded to the body of the document to high temperature, and under high pressure. This welding step is called "lamination" in the professional language. The sheet of lasérisable material, protects the security reasons and decoration previously printed on the body of the document. This sheet of lasérisable material is called "the overlay" in professional language. Then, according to a known technique, a carbon laser beam in the overlay, shows a black and white image that is often the identity photo of the owner of the secure document. The laser carbonization of the overlay prohibits counterfeiting, whereas a simple image obtained by inkjet printing or thermal transfer, for example, offers a much lower degree of security, because these inks can be removed by a chemical process or mechanical. To ensure good contact privacy during the lamination of the overlay on the document body, it is practiced on the surface of the overlay, intended to be laminated on the body of the document, an artificial roughness. This artificial roughness is obtained by hot pressing the overlay on a mother surface having the required roughness. The roughness of the mother is then transferred to the surface of the overlay. The main purpose of this roughness is to prevent the formation of small air bubbles trapped during lamination.

The patent application No. 10 01415 entitled "device for personalization of embedded latent images" filed on April 7, 2010, describes a structure comprising a matrix of sub pixels primary colors red green blue, (which will be named by the matrix suite of sub pixels (R, G, B), (like red, green, blue, according to the Anglo-Saxon language) making it possible to carry out by laser carbonization, a laser color image, by showing the gray levels on each sub-pixel thus forming a high-quality color image The patent application FR 11/00578 filed on February 28, 2011, bearing the title "Method of forming a reflective high-performance color laser image and document on which a color laser image is thus achieved "proposes to print the sub-pixels (R, G, B) on the surface of the overlay intended to be laminated on the body of the document, and to reserve unprinted areas between the sub-pixels (R, G , B) to strengthen the predominantly white and the reflectivity of laser color images. However, printing the sub pixels (R, G, B) on the rough surface of the overlay before it is rolled on the document body degrades the print quality of the sub pixels (R, G). , B). RGB colored surfaces are inhomogeneous, contours are irregular, and colors are dull.

SUMMARY OF THE INVENTION The object of the present invention is to overcome this drawback by proposing a method for producing a substrate for a color laser image, and a secure document implementing this method. The invention includes an overlay on which the matrix of sub pixels (R, G, B) is printed on a surface required for printing, this substrate also having the roughness required for quality rolling. This object of the invention is achieved thanks to the realization on the surface of the overlay intended to be laminated, of smooth surfaces able to receive the impression of the matrix of sub-pixels (R, G, B), and around of these smooth surfaces, surfaces with roughness required for the lamination of the overlay on the body of the document.

More specifically, the object of the invention is a method of producing a color laser image substrate, comprising a transparent sheet of lasérisable material, having a face intended to be laminated on the body of an identity document.

On this face are formed by hot pressing one or more smooth surfaces that can be printed with one or more matrices of sub pixels (R, G, B). These smooth surfaces are surrounded by rough surfaces capable of being laminated on the body of an identity document. According to another embodiment of the invention, microcavities, having a smooth bottom, are formed by hot pressing on the surface of the substrate intended to be laminated on the body of the document. These microcavities have the geometry of sub pixels (R, G, B) and are able to be printed in the form of sub-pixels. When printing the sub-pixels (R, G, B) the ink with red, green, or blue colors, is housed in these microcavities, and takes the geometry. The surfaces surrounding the microcavities have a roughness required to be laminated on the body of an identity document, and are not covered with colored ink. These rough surfaces surrounding the microcavities, after rolling on the body of an identity document, ensure the mechanical cohesion of the transparent sheet of lasérisable material on the body of the document. The smooth surfaces, the microcavities, and the roughness surrounding them are obtained by hot pressing on a mother surface, the face of the transparent sheet of lasérisable material to be laminated on the body of the document. Once laminated, on the body of the document, the color laser image substrate serves as a protective layer. According to particular embodiments: --Before printing subpixels (R, G, B) a layer of reflective varnish is printed --After printing subpixels (R, G, B) a layer of reflective varnish is printed on the sub pixels (R, G, B) The invention also relates to a document implementing the method for producing a color laser image substrate, described above. The document comprises an identity document body, a transparent sheet of lasérisable protective material, laminated on the identity document body. On the face of the transparent sheet to be laminated on the document body, a matrix of sub pixels (R, G, B) is printed on smooth surfaces formed by hot pressing. These smooth surfaces are surrounded by rough surfaces that are laminated on the body of the identity document. According to another embodiment of the invention, on the face of the lasérisable transparent sheet, intended to be laminated on the document body, microcavities having a smooth bottom, formed by hot pressing, are printed with sub-pixels (R, G , B). When printing, the RGB ink of the sub pixels (R, G, B) is housed in these microcavities, and takes the geometry. The surfaces surrounding the microcavities have a roughness required for their rolling on the body of an identity document, and are not covered with colored ink. These rough surfaces surrounding the microcavities, after rolling on the body of an identity document, ensure the mechanical cohesion of the substrate on the body of the identity document. A laser beam exposes the gray levels of a customized color laser image by carbonization in the lasable, transparent protective layer. According to particular embodiments: - A layer of reflective varnish is deposited on the smooth surfaces before printing the sub-pixels (R, G, B) - After printing the sub-pixels (R, G, b) a layer of reflective varnish covers them.

Presentation of the Figures: The invention will appear better after the description which follows, given for explanatory purposes and in no way limiting. This description refers to the accompanying drawings, in which: - Figure 1 shows the section of a lasérisable protective sheet, according to the prior art.

FIG. 2 shows the section of an identity document comprising a laser image flowing according to the prior art.

FIG. 3 shows the section of an overlay according to a first embodiment of the invention

FIG. 4 shows the section of an overlay according to another embodiment of the invention

FIG. 5 shows the section of an identity document according to a mode of the invention.

DETAILED DESCRIPTION FIG. 1 shows the section (10) of an overlay (1) according to the prior art, made of transparent lasérisable material. Laserizable materials are, by way of non-limiting examples, polycarbonates, certain polyvinyl chlorides treated, acrylonitrile-butadiene-styrenes treated, or treated polyethylene terephthalates ethylene. The face (2) intended to be laminated on the body of an identity document, has a certain roughness known to those skilled in the art, in order to prevent the formation of air bubbles and to ensure a privacy of contact during lamination. FIG. 2 shows the section (20) of an identity document according to the prior art, comprising the body (3) of the identity document, the protective sheet of lasérisable materials (1), which has been laminated on the body of the identity document (3) by high temperature pressing. A matrix of sub pixels (R, G, B), (4) is trapped during the rolling between the transparent protective sheet (1) and the body (3) of the identity document. The sub pixels (R, G, B) are separated by an unprinted transparent area (T). A laser beam (6), through the transparent protective layer (1), reveals black, non-reflecting surfaces (5) by carbonization, which form the gray levels of a personalized laser color image. Figure 3 shows the section of a transparent lasérisable protection sheet (1) according to a first embodiment of the invention. On the face (2) of the transparent protective sheet intended to be laminated on the body of an identity document, one or more smooth surfaces (33) and a roughness required for lamination, surrounding the smooth surface (s) (33) were hot formed by pressure on a mother surface having the same negative profiles. In a second step, one or more matrix (4) subpixels (R, G, B) is printed on the smooth surface (s) (33), according to printing techniques known to those skilled in the art. The areas of the smooth surface (s) (33) and the matrix or matrices of sub pixels (R, G, B) (4) are substantially equal. FIG. 4 shows the section (40) of a laserizable transparent protective sheet (1) according to another embodiment of the invention. Inkjet printing, or offset techniques for example, to print the sub-pixels (R, G, B) do not allow to realize very small color patterns with precision. Indeed, once deposited, the ink migrates more or less on the edges of the patterns. Thus, the limits of color ink printing, make it difficult to print sub-pixels having dimensions less than 40pm or 50pm approximately. Some high definition images, however, require smaller sub pixels. To remedy this, the face (2) of the lasérisable transparent sheet (1) intended to be laminated on the body of an identity document, has microcavities (42) having a smooth bottom, surrounded by rough surfaces, suitable for lamination . These microcavities (42) and the roughness surrounding them, were formed by hot pressing on a mother surface having the same negative profiles. The microcavities (42) have the shape and the size of the sub pixels (R, G, B). In a second step, the sub-pixels (R, G, B are printed in the microcavities, the ink thus deposited (43) in these microcavities (42) matches the geometry of these microcavities, and Figure 5 shows the section (50). ) an identity document, made from the method previously described, comprising a document body (3), a transparent protective sheet of laserizable material (1), and the face (2) of the protective sheet (1). ) before lamination, microcavities (42), having a smooth bottom, surrounded by rough surfaces were hot pressed on a mother surface that gave them this profile.In the microcavities, sub pixels (R, G, B) were The red, green and blue colored inks (43) deposited during the printing take the geometry of the microcavities (42) According to a first embodiment of the invention, described in FIG. printed on one or more smooth surfaces (33) surrounded by These profiles are obtained by hot pressing on the surface of a mother who gives them this profile. The transparent protective sheet (1) is then laminated to the body of an identity document (3). During the customization of the identity image, a laser beam (6) through the transparent protective layer (1) generates, by carbonization, the gray levels (5) of the personalized image.

Claims (10)

REVENDICATIONS1. A method of producing a color laser image substrate, comprising a transparent sheet of lasérisable material (1) having a face (2) to be laminated to the body of an identity document (3) characterized in that this face (2) is formed by hot pressing, one or more smooth surfaces (33) capable of being printed with one or more matrices of sub pixels (R, G, B), (4) and are surrounded by surfaces Rough enough to be rolled on the body of an identity document. 20 Method for producing a color laser image substrate according to Claim 1, characterized in that microcavities (42) having a smooth bottom are formed by hot pressing on the surface (2) of the substrate intended to be laminated on the body of the document, these microcavities having the geometry of the sub-pixels (R, G, B) and are able to be printed in the form of sub-pixels. 3. A method for producing a color laser image substrate, according to claim 2, characterized in that during printing of the sub-pixels (R, G, B) the ink (43) in red, green colors or blue is lodged in these microcavities, and takes the geometry. 105 4. Process for producing a color laser image substrate according to claim 2, characterized in that the surfaces surrounding the microcavities have a roughness required to be laminated on the body of an identity document. (3) and in that these rough surfaces after rolling on the body of an identity document, ensure the mechanical cohesion of the transparent sheet of lasérisable material, and the body of the identity document (3). 5. A method of producing a color laser image substrate, according to any one of claims 1 to 4, characterized in that the sub pixels (R, G, B) are printed on a layer of reflective varnish. 6. A method of producing a color laser image substrate, according to any one of claims 1 to 5, characterized in that a layer of reflective varnish is printed on the sub pixels (R, G, B). 7. Document implementing the method for producing a color laser image substrate, described above, characterized in that the document comprises an identity document body (3), a transparent sheet of lasérisable protective material (1), on the face (2) of this transparent sheet intended to be laminated on the document body, one or more sub-pixel matrices (R, G, B) are printed on one or more smooth surfaces, formed by hot pressing, which are surrounded by rough surfaces, the assembly being laminated on the body of the identity document (3) and in that a laser beam (6) makes the gray levels appear in the lasperizable transparent protective layer (1) (5) one or more custom color laser images. 8. Document implementing the method for producing a color laser image substrate, described above, according to claim 7, characterized in that the face of the lasérisable transparent sheet comprises microcavities formed by hot pressing, having a smooth background, in which are printed sub-pixels (R, G, B), the ink (43) in green and blue red colors, sub-pixels (R, G, B) is housed in these microcavities, and takes the geometry, and in that the rough surfaces surrounding the microcavities ensure the mechanical cohesion of the substrate on the body of the identity document (3). 9. Document implementing the method for producing a color laser image substrate, described above, according to claims 7 and 8, characterized in that the sub pixels `R, G, b) are printed on a reflective varnish. 10. Document implementing the method for producing a color laser image substrate, described above, according to claims 7 to 9, characterized in that a reflective varnish is printed on the sub pixels (R, G, B). 30