Back-lit Colour Laser Image in Transparent Identity Documents
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Solution Overview
Problem
Colour laser images on identity documents require additional illumination to enhance luminosity, as they may not be sufficiently visible in various environments without external light sources.
Innovation Solution
A method for creating a back-lit colour laser image using a transparent identity document body through which a light flow passes, illuminating the image from behind, with sub-pixels protected by a laserable sheet and decorative patterns and anti-counterfeit systems on both sides, including tiny holes or diffraction elements for light entry and enhancement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transparent protective sheet is used to protect sub-pixels, then the colour laser image can be formed, but additional illumination is required to enhance luminosity and visibility
Solution Approach 1:
A transparent sheet with laser-written channels acts as an intermediary between the light source and the colour laser image. The channels guide and concentrate light from the back of the document to illuminate the image from behind, enhancing luminosity while maintaining the protective function of the transparent sheet
Solution Approach 2:
The illumination approach shifts from front-side reflection to back-side transmission by creating light channels through the transparent sheet. This dimensional change in light path allows the image to be lit from behind, improving visibility without compromising protection
2Manufacturing precision
If carbonization is used to create grey levels in the transparent sheet, then a high quality personalised colour laser image is formed, but the sheet becomes less transparent and requires back lighting
Solution Approach 1:
The transparent sheet has locally differentiated properties: areas with laser-written channels have modified optical properties for light guidance, while other areas remain transparent for image visibility. This local quality variation allows simultaneous image formation and light transmission
Solution Approach 2:
The laser-written channels in the transparent sheet serve as optical intermediaries that guide light from the back illumination source to the colour laser image, compensating for the reduced transparency caused by carbonization
3Illumination intensity
If the document body is made transparent to allow back lighting, then the colour laser image is illuminated from behind, but decorative patterns and anti-counterfeit systems must be carefully integrated
Solution Approach 1:
The document structure is segmented into functional layers: transparent body, back lighting source, decorative patterns with light channels, and protective transparent sheet. This segmentation allows each element to perform its specific function while maintaining overall system integrity
Solution Approach 2:
The transparent sheet serves multiple functions: protecting the colour laser image, guiding light through laser-written channels, and allowing visibility of decorative patterns and anti-counterfeit systems on the back of the document
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method ensures the colour laser image is efficiently illuminated from behind, enhancing visibility and luminosity without compromising the quality of decorative patterns or anti-counterfeit systems, and can be implemented using various transparent materials and light sources.
Implementation Method 1
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
Implementation Method 2
a light flow passes through it which back lights the personalised colour laser image perpendicular to its plane
Implementation Method 3
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
Implementation Method 4
Reflective means located on the reverse side of the identity document enhance the intensity of the light sent through the personalised laser image
Data Source
AI summary
This disclosure includes a system and method for producing a back-lit color laser image, and an identity document using this method and back lighting system. The body of the identity document may be transparent. In various implementations, the light back-lights the color laser image which may be formed of sub-pixels partly covered by non-reflective surfaces in the protective layer. The light may enter through tiny holes in decorative patterns on the reverse side of the document. Various implementations may find particular applications for identity cards, credit cards, passports, driving licences, secure entry badges, etc.