UV Laser Pigment Bleaching for High-Fidelity Color Images
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Solution Overview
Problem
Current methods for producing color images on official cards using laser technology face challenges in achieving high-quality color reproduction due to complexity, cost, and image defects, particularly with the interaction between pigment absorption spectra and laser wavelengths, leading to reduced image quality and increased costs.
Innovation Solution
A spatially resolving method using a single irradiation frequency to locate and selectively bleach pigment particles on a substrate, allowing for high-quality color image production with precise control over pigment particles, ensuring each area element is occupied by a single color component and minimizing overlap, thereby avoiding spectral crosstalk and improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple colouring components with different absorption spectra are used for laser bleaching, then colour image production is enabled, but spectral crosstalk occurs reducing image quality
Solution Approach 1:
The patent segments the pigment layer into spatially separated regions, each containing a specific colouring component (cyan, magenta, yellow) at distinct locations. This spatial segmentation allows selective laser irradiation of individual pigment regions without spectral interference from other colours, eliminating spectral crosstalk while maintaining full colour image production capability.
Solution Approach 2:
The invention applies local quality by assigning specific colouring components to specific spatial locations within the pigment layer. Each region has a defined local composition (e.g., cyan at position X, magenta at position Y) that matches the desired image output, allowing precise control over which pigment absorbs which laser wavelength at each location.
2Adaptability or versatility
If multiple coincident laser beams are used to address different colouring components, then colour reproduction is improved, but device complexity and control difficulty increase
Solution Approach 1:
The patent segments the colouring components into spatially separated regions rather than using multiple coincident laser beams. This allows a single laser beam to irradiate different pigment regions sequentially or in a controlled manner, reducing device complexity while maintaining colour reproduction quality through the segmented spatial arrangement of pigments.
3Manufacturing precision
If pigment particles are densely packed to improve image resolution, then image quality improves, but spectral interaction between adjacent pigments increases
Solution Approach 1:
The patent uses spatial segmentation to separate different colouring components into distinct regions with defined boundaries. This segmentation allows high-density packing of pigment particles within each region while preventing spectral interaction between adjacent regions of different colours, as each region's pigment is selectively irradiated at its optimal wavelength.
Solution Approach 2:
The invention implements local quality by creating distinct spatial zones with specific pigment compositions. Each local region has optimized pigment density and composition tailored to its function, allowing high resolution within each region while minimizing spectral interference between regions through controlled spatial separation.
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
This method enables the production of high-quality color images with improved security against forgery, reduced costs, and increased robustness, meeting market standards for quality and cost-effectiveness while maintaining a high level of security.
Implementation Method 1
The colouring components of different colour must together produce a coloured space... These are of course colours from the RGB system, with which there is in practice a partial incompatibility or non-ideal interaction between the colour components of the CMY system and the laser wavelength selected for the absorption maximum.
Implementation Method 2
The basic colours must also have an absorption spectrum which allows interaction with coloured laser light... the absorption spectra of most colour components used are created in such a manner that there is to a certain extent an undesirable interaction between one colouring component and another laser wavelength than the one desired.
Data Source
AI summary
A method is described for producing a character, pattern, symbol and/or image (8) on a substrate (2) by way of pigment particles (1) which are arranged thereon and lose their color effect under the action of a laser (23), wherein different pigment particles (1) with at least three different color effects are arranged on and/or in the substrate (2). The invention is distinguished by the following method steps: (a) production of a color chart (14), in which the individual color effect of individual pigment particles (1) or individual clusters of pigment particles is contained as a function of their spatial coordinate on and/or in the substrate (2); (b) spatially resolved irradiation, which changes the color effect of only individual pigment particles (1) or individual clusters of pigment particles, by way of a laser (23) at a single frequency on the basis of the color chart (14) in order to produce a resulting color effect. Furthermore, the present invention relates to substrates, in particular security documents, produced using a method of this type, and devices for carrying out methods of this type.