This application is a U.S. National Stage application of PCT/FR2012/000060 filed Feb. 16, 2012, which claims priority to French Application No. 11/00606 filed Mar. 1, 2011, the entire disclosures of which are hereby incorporated by reference in their entireties.
The present invention concerns the forming of a colour laser image that can be seen in three dimensions. It finds application in particular in identity images dedicated to official documents: identity cards, credit cards, national health insurance cards, passports, driving licenses, secure entry badges, etc.
Modern identity cards are composed of a plastic substrate comprising various decorative, identification or anti-counterfeit designs covered with a transparent protective sheet. The transparent protective sheet is hot welded under strong pressure onto the plastic substrate of the document. This operation is known as <<lamination>> in the trade.
In addition to the designs printed on the substrate, identity documents must carry the identity photo of the owner. This identity photo is produced by a laser beam which, by passing through the transparent protective sheet called <<laserable>> in the remainder hereof, generates grey levels via carbonization in this protective sheet. A secure black and white image is thus obtained. It cannot be replaced by an image printed by inkjet for example without destroying the identity document.
To raise the security level further, it has been proposed, to produce these black and white laser images having a three-dimensional appearance. U.S. Pat. No. 4,765,656 describes a data substrate coated with cylindrical lenses through which a laser beam via carbonization engraves two black and white images differing through the tilt angle of the laser beam. The reverse pathway of the light enables the observer to see one or other of the images depending on the tilt angle of the substrate.
Patent WO2006110038A2 starting from the preceding device describes the viewing in relief of an object photographed at two different angles, the two laser images reproducing these two photos, enabling the observer to see the image of the object in black and white, the object through cylinder lenses giving a three-dimensional appearance.
Patent applications FR 10 01415 carrying the title <<Device for customizing embedded latent images>> filed on Apr. 7, 2010 and patent application FR 11/00578 filed on Feb. 28, 2011 carrying the title <<Method for forming a colour laser image with high reflective yield, and document in which a colour laser image is thus produced>> describe an assembly comprising a matrix of pixels formed of sub-pixels in the primary colours embedded underneath a transparent laserable protective sheet. By means of a laser beam passing through the transparent protective sheet, grey levels are created in the laserable protective sheet covering the RGB sub-pixels with a black non-reflective surface. This treatment, allows the personalisation of a colour laser image of high quality. The primary colours RGB (abbreviation for red green and blue) are obtained by mixing equal portions of the primary colours yellow, magenta and cyan (abbreviated to YMC). Therefore the primary colours RGB in fact comprise the YMC colours from which they derive. These triplets of colours RGB, YMC are said to be independent since the mixing of two colours of one same triplet cannot form the third colour of this same triplet. There therefore exists a large number of triplets of independent colours and hence of primary colours.
In the remainder hereof the term (RGB) sub-pixels shall be given to those sub-pixels whose colours meet the definition of independent colours and correspond to the colours detected by the RGB rod cells (red, green, blue) of the human eye.
Although of advantage in some respects, these structures of colour laser images do not allow viewing in relief.
It is the objective of the present invention to overcome the disadvantages of the prior art by proposing a colour laser image offering three-dimensional viewing.
For this purpose the invention proposes a matrix of pixels comprising sub-pixels in the primary colours which in the remainder hereof shall be termed (RGB) sub-pixels, an array of optical lenses deflecting the laser beam at the time of engraving via carbonization of the laserable protective sheet to form the grey levels of the (RGB) sub-pixels which, depending on the angle of incidence of the laser beam, produce two different colour laser images and by reflection of the ambient light cause these two different colour laser images to be seen separately or simultaneously in this case producing via stereoscopic effect a colour laser image to appear in relief.
More specifically, the subject of the invention is a method for forming two different colour laser images from an assembly comprising a substrate, a laserable protective sheet, an array of cylinder optical lenses, pixels formed of (RGB) sub-pixels printed in primary colours in the form of parallel columns (C1,C2,C3). A laser beam, through the array of optical lenses and via carbonization in the laserable protective sheet opposite each (RGB) sub-pixel, causes the grey levels to appear of two different colour laser images derived from two photos of one same subject taken at different angles. These two colour laser images, by reverse reflection of ambient light through the array of lenses, appear to the observer as a three-dimensional colour laser image of the subject.
The lens array is composed of parallel cylinder lenses and the (RGB) sub-pixels in parallel, columns in the primary colours have their major axis located perpendicular to the major axis of the cylinder lenses of the lens array.
The matrix of (RGB) sub-pixels is printed on the laserable protective sheet by offset, inkjet, thermal transfer or any other technique. According to one variant it can be printed on the substrate.
At a second production step called <<lamination>> the laserable protective sheet is hot welded under pressure onto the substrate of the document trapping the matrix of (RGB) sub-pixels between the laserable protective sheet and the document substrate. Lamination, on the upper surface of the laserable protective sheet, forms the array of lenses. This array partly or wholly covers the matrix of (RGB) sub-pixels.
From two stereoscopic images of one same subject taken from two different angles, the forming of the images subject of the invention appearing to produce an image in relief of the subject, is obtained by means of a laser beam which carbonizes the laserable protective sheet in the thickness thereof, as per variable intensities or surfaces opposite each (RGB) sub-pixel, the laser beam scanning the columns (C1,C2,C3) of sub-pixels parallel to the major axis of these columns and having a certain angle of incidence relative to the plane of the lens array, it is deflected by this array and via carbonization in the laserable protective sheet causes the grey levels of two different images to appear corresponding to the two stereoscopic images of the subject.
The ambient light follows the reverse pathway of the laser beam and is reflected through the array of lenses at different angles, the two colour laser images which via stereoscopic effect are seen by the observer in a direction perpendicular to the plane of the document then appearing as a single image in three dimensions.
The invention also concerns a document comprising a colour laser image which can be seen in three dimensions by implementing the above method. This document comprises a laserable protective sheet on which an array of lenses has been hot printed. This sheet is at least partly carbonized by a laser beam. Printed pixels comprise (RGB) sub-pixels in the form of columns. They are located underneath the array of lenses and have the same surface. The laserable protective sheet on which the array of lenses is positioned, the columns of (RGB) sub-pixels and the document substrate are able to be laminated together.
The axis of the lens array is perpendicular to the axis of the columns of (RGB) sub-pixels. The forming of the colour laser image observable in three dimensions is obtained in the document via a laser beam which scans through the lens array along the axis of the columns of (RBG) sub-pixels at a first angle of incidence relative to the plane of the lens array forming the grey levels in the laserable protective sheet of a first colour laser image taken from a first angle of the subject, and at a second angle of incidence relative to the plane of the lens array forming the grey levels of a second colour laser image taken from a second angle of the subject. The two colour laser images via reverse reflection of ambient light through the array of lenses appear to the observer to be one colour laser image in three dimensions of the subject.
The invention will become better after the following description given for explanatory purposes and in no way limiting. This description refers to the appended drawings in which:
As non-limiting examples the laserable materials may be polycarbonates, some treated polyvinyl chlorides, treated acrylonitrile-butadiene-styrenes or treated polyethylene terephthalates. The laserable material is partly carbonized by the laser to form grey levels of a personalised image. The laserable protective sheet is transparent and has a thickness of between 20 μm and 500 μm.
Laser scanning is performed along the axis 31 at a first angle of incidence 43 relative to the plane of the lens array, forming the grey levels 46 of a first colour laser image taken from a first angle of the subject, and at a second angle of incidence 44 relative to the plane of the lens array forming the grey levels 45 of a second colour laser image taken from a second angle of the subject.
Number | Date | Country | Kind |
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11 00606 | Mar 2011 | FR | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/FR2012/000060 | 2/16/2012 | WO | 00 | 10/8/2013 |
Publishing Document | Publishing Date | Country | Kind |
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WO2012/117169 | 9/7/2012 | WO | A |
Number | Name | Date | Kind |
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4765656 | Becker et al. | Aug 1988 | A |
5543381 | Kishimoto et al. | Aug 1996 | A |
8006908 | Bergmann et al. | Aug 2011 | B2 |
8314828 | Bombay et al. | Nov 2012 | B2 |
20090214105 | van den Berg | Aug 2009 | A1 |
Number | Date | Country |
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43 39 216 | Apr 1994 | DE |
2005058610 | Jun 2005 | WO |
2006110038 | Oct 2006 | WO |
Entry |
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International Search Report and Written Opinion dated Jun. 1, 2012 for International Application No. PCT/FR2012/000060 filed Feb. 16, 2012, pp. 1-11. |
Number | Date | Country | |
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20140028775 A1 | Jan 2014 | US |