Identity Document Latent Image Personalization Resolution
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Solution Overview
Problem
Existing methods for personalizing identity documents with latent images face challenges in achieving high resolution in both directions, particularly when elementary zones are formed in parallel lines, leading to limitations in detail reproduction and contrast.
Innovation Solution
A method involving a network of single-color portions distributed in groups, where segments extending over these portions allow for varying darkening levels to reproduce image pixels, with each segment defined by a pixel and an adjacent pixel, enabling better resolution transversely to color lines by generating successive darkening levels across multiple pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If elementary zones are formed in parallel lines to simplify manufacturing, then ease of manufacture is improved, but resolution transverse to color lines deteriorates
Solution Approach 1:
The patent segments the image processing into two distinct phases: a first pass that processes pixels in the longitudinal direction (parallel to color lines) and a second pass that processes pixels in the transverse direction (perpendicular to color lines). This segmentation allows each pass to optimize for its specific direction, achieving high resolution in both directions while maintaining the simplicity of parallel line formation during manufacturing.
Solution Approach 2:
The patent introduces a temporal dimension by performing two sequential processing passes instead of attempting to achieve full 2D resolution in a single pass. The first pass handles the longitudinal direction and the second pass handles the transverse direction, effectively using time as an additional dimension to resolve the contradiction between manufacturing simplicity and transverse resolution.
2Ease of manufacture
If laser beam diameter is increased to match offset printing line width, then ease of manufacture is improved, but printing resolution deteriorates
Solution Approach 1:
The patent segments the resolution requirement into two independent directional components. By processing longitudinal and transverse directions in separate passes, the system can use larger laser beams for longitudinal processing (matching offset printing capabilities) while achieving fine transverse resolution through the second pass, thus resolving the contradiction between beam size and overall resolution.
Solution Approach 2:
The patent employs dynamic adjustment of processing parameters between the two passes. The first pass uses parameters optimized for longitudinal resolution with larger beam diameters suitable for offset printing, while the second pass uses parameters optimized for transverse resolution. This dynamic adaptation allows the system to match manufacturing constraints while achieving high overall resolution.
3Manufacturing precision
If multiple impacts are generated across a line to maintain resolution, then printing resolution is improved, but device complexity increases
Solution Approach 1:
The patent segments the multiple impact generation into two organized sequential passes rather than requiring complex simultaneous multi-directional processing. The first pass generates impacts for longitudinal resolution and the second pass generates impacts for transverse resolution, simplifying the device architecture compared to systems that would need to handle multiple directions simultaneously.
Solution Approach 2:
The patent uses periodic action by implementing two distinct processing passes with different parameter sets. The first pass operates with parameters optimized for longitudinal processing, then the system periodically switches to the second pass with parameters optimized for transverse processing. This periodic alternation between two simple modes is less complex than maintaining continuous multi-directional processing capability.
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 approach enhances the resolution of the personalization image both parallel and transverse to color lines, improving detail reproduction without compromising color rendering.
Implementation Method 1
such darkening can be carried out by local thermal effect, or by local photosensitive effect
Implementation Method 2
in practice this darkening is obtained by total or partial carbonization of each of the elementary zones concerned, typically by application of a laser beam
Implementation Method 3
the transparent mechanical protection layer has the effect of preventing document handling operations from altering the latent image
Data Source
Figure 1~2
AI summary
A method for visually customising an identity document comprising a latent image formed from an array of single-colour portions distributed into a series of groups of identical single-colour portions, comprises steps which involve, for each pixel of a customisation image to be formed on the latent image, defining a segment extending over one of said groups of single-colour portions, each segment being formed from elementary areas in which shading can be generated with a level chosen from a plurality of possible shading levels so as to locally alter the appearance of the array in such a way as to reproduce, in said segment, said colour of the pixel of the customisation image, characterised in that, the portions having a dimension representing, at most, a multiple of the average dimension of these elementary areas, it involves generating, in at least some of the segments, successive levels of shading that are respectively defined by a pixel of the image to be reproduced and by at least one adjacent pixel in this image to be reproduced in a given position.