Aperiodic Mask Pattern for High-Speed Inkjet Printing
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Solution Overview
Problem
Conventional mask patterns for multi-pass printing often compromise between high-quality image formation and high-speed printing, as they either result in end stripes due to nozzle misalignment or require lower scanning speeds to maintain image quality, and existing periodic arrangements fail to achieve both high-quality and high-speed printing simultaneously.
Innovation Solution
A method and apparatus for generating print data that uses mask patterns with non-adjacent and aperiodically arranged print permitting areas, where the printing ratios decrease from central to end nozzles, allowing for high-speed printing without compromising image quality by ensuring non-adjacency of print permitting areas in the scanning direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional mask patterns with periodic arrangements are used, then image quality is maintained through proper nozzle coverage, but printing speed is reduced due to adjacent print permitting areas requiring slower scanning
Solution Approach 1:
The patent applies periodic action by using multiple mask patterns (first, second, third, and fourth mask patterns) that are systematically arranged and applied in sequence across different scanning passes. Each mask pattern has a specific periodic structure that distributes print permitting areas in a controlled manner, ensuring comprehensive nozzle coverage while maintaining regularity that facilitates high-speed printing through optimized scanning sequences.
Solution Approach 2:
The patent segments the printing process into multiple scanning passes, each using a different mask pattern. The nozzles are divided into multiple groups, and each group is activated in specific passes according to its mask pattern. This segmentation allows adjacent nozzles to be deactivated in certain passes, creating non-adjacent print permitting areas that enable high-speed printing while still achieving complete coverage through the combination of all passes.
2Manufacturing precision
If mask patterns with higher printing ratios at end nozzles are used, then complete coverage is achieved, but end stripes occur due to inward droplet ejection deviation
Solution Approach 1:
The patent applies local quality by assigning different printing ratios to different nozzle groups based on their position. Specifically, nozzle groups at the end portions of the printing head (fifth and sixth nozzle groups) are assigned a first printing ratio, while central nozzle groups (second, third, and fourth nozzle groups) are assigned a second printing ratio that is higher than the first. This localized differentiation compensates for the inward deviation of droplets from end nozzles without over-printing, thereby preventing end stripe formation while maintaining complete coverage.
Solution Approach 2:
The patent changes the printing ratio parameter across different nozzle groups and scanning passes. By dynamically adjusting which nozzles are active in each pass according to their position-specific printing ratios, the system optimizes droplet placement accuracy. This parameter change strategy ensures that end nozzles do not over-print due to inward deviation, thus preventing end stripes while achieving uniform coverage.
3Manufacturing precision
If multiple scanning passes are performed, then nozzle variation and conveyance precision variation are reduced, but printing time increases
Solution Approach 1:
The patent uses periodic action by implementing a cyclic multi-pass printing process where different nozzle groups are activated in a systematic sequence. The first and second nozzle groups are activated in the first scanning pass, while the third and fourth nozzle groups are activated in the second scanning pass, with similar patterns continuing for subsequent passes. This periodic activation pattern ensures that each region receives multiple printed patterns from different nozzle groups, reducing the effects of nozzle variation and conveyance precision errors, while the regularity of the cycle optimizes printing efficiency.
Data Source
AI summary
Mask patterns to be used for multi-pass printing make it possible to make a print with a higher quality at a higher speed. Specifically, by performing a swapping process with adjacency forbiddance, two points in the horizontal direction, or the scanning direction of a printing head, are selected in a buffer in which codes for each scan pass are set depending on printing ratios of a gradation mask. Subsequently, codes are swapped between the two points. By this swap, adjacencies between print permitting areas are eliminated in the mask pattern. As a result, when driving frequencies set for the printing head is kept constant, the scanning speed can be doubled at minimum.