Multi-Beam Ablative Imaging with Dynamic Shift Patterns
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Solution Overview
Problem
Ablative imaging in flexography printing using multiple beams often results in visible stitching lines due to the transfer of imaging data, leading to stitching artefacts that disrupt the homogeneity of the image, with existing methods either requiring more beams than necessary or causing irregularities in the image pattern.
Innovation Solution
A method and apparatus that utilize overlapping patterns with strategically selected pixel locations for each row, allowing for the simultaneous writing of imageable material using multiple beams, where the first and second patterns overlap with 'holes' in the first pattern filled by the second pattern, and varying the number of selected pixels per row to avoid straight edges and ensure all pixel locations are written once.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple beams simultaneously form groups of tracks on the plate, then productivity is improved by exposing multiple areas at once, but visible stitching lines appear between beam groups disrupting image homogeneity
Solution Approach 1:
The patent implements dynamic shifting of beam groups in the slow scan direction between successive fast scan passes. The shift amount varies dynamically to break up regular stitching patterns, transforming the static, predictable stitching lines into dynamic, irregular patterns that are less visible to the human eye
Solution Approach 2:
The patent introduces asymmetric shift amounts between different beam groups and between successive passes. By using non-uniform, irrational number shifts rather than symmetric integer shifts, the stitching lines become irregular and non-repeating, reducing their visual detectability while maintaining the productivity benefits of multiple simultaneous beams
2Manufacturing precision
If beam groups are shifted into each other to break up stitching lines, then image homogeneity is improved, but the complexity of coordinating multiple beams increases
Solution Approach 1:
The patent changes the parameter of shift amount from fixed integer values to variable values including irrational numbers. This parameter change allows breaking up stitching patterns while providing a systematic method for calculation, managing the coordination complexity through mathematical formulation rather than ad hoc adjustments
Solution Approach 2:
The patent performs preliminary calculation of shift amounts using irrational numbers before the exposure process begins. By pre-determining the asymmetric shift patterns, the system reduces real-time coordination complexity during actual exposure while still achieving the goal of breaking up visible stitching lines
3Manufacturing precision
If overlapping patterns are used to fill holes in the first pattern, then all pixel locations are written once improving image quality, but the processing complexity increases
Solution Approach 1:
The patent segments the image data into multiple patterns that are processed and exposed in sequence. By dividing the complete image into segments with overlapping regions, each containing holes to be filled by subsequent patterns, the system ensures complete coverage while managing data processing in manageable segments
Solution Approach 2:
The patent merges multiple segmented patterns with overlapping regions into a complete image. The overlapping areas where holes in one pattern are filled by corresponding data in the next pattern are combined to ensure all pixel locations are written exactly once, improving image quality through systematic data integration
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 effectively minimizes stitching artefacts, allowing for a faster and more efficient exposure process with improved image quality by ensuring that all pixel locations are written once and distributing power efficiently among the beams, resulting in a higher process speed.
Implementation Method 1
Ablative imaging is used in flexography printing. A flexographic plate, e.g. a rubber or photopolymer plate, is provided with relief areas corresponding to zones to be inked and floor areas corresponding to zones not to be inked.
Implementation Method 2
N beams are available and N is at least four... writing simultaneously, for each row i, said Mi1 selected pixel locations by moving the N beams in a fast scan direction relative to said imageable material
Data Source
AI summary
A method for writing an imageable material using multiple beams includes preparing subsequent patterns each having Y rows of N pixel locations, said subsequent patterns including first and second patterns; where the first and the second pattern overlap with each other in an overlap area consisting of O columns and Y rows of pixel locations; selecting for each row i of said first pattern Mi1 pixel locations; selecting for each row i of said second pattern Mi2 pixel locations; writing simultaneously, for each row i, said Mi1 selected pixel locations by moving the N beams in a fast scan direction relative to said imageable material; and moving said N beams relative to said imageable material in a slow scan direction over (N-O) pixel locations; writing simultaneously, for each row i, said Mi2 selected pixel locations by moving the N beams in a fast scan direction relative to said imageable material.