Variable Sub-scanning Distance for Ink Jet Banding Control
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Solution Overview
Problem
Ink jet printers experience banding issues due to extended landing ranges of ink droplets during high-speed main scanning, leading to dark stripes and reduced printing speed, especially in band printing and pseudo-band printing schemes.
Innovation Solution
A printing control device that adjusts the sub-scanning distance based on the gap between the recording head and the platen, and the record density, to maintain optimal ink droplet landing ranges, thereby suppressing banding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the speed of main scanning of the recording head is increased to improve printing speed, then the landing range of ink droplets is extended in the sub-scanning direction, but dark stripes occur in the main scanning direction due to overlapping bands
Solution Approach 1:
The patent applies dynamics by making the sub-scanning distance variable rather than fixed. The sub-scanning control unit dynamically adjusts the sub-scanning distance based on the actual gap between the recording head and platen, allowing the system to adapt to different operating conditions while maintaining optimal printing quality at high speeds
Solution Approach 2:
The patent changes the parameter of sub-scanning distance based on the gap between recording head and platen. By measuring or detecting the gap and corresponding it to an appropriate sub-scanning distance, the system optimizes ink droplet placement to prevent banding while maintaining high printing speeds
2Manufacturing precision
If partial overlap printing is performed to reduce banding, then print regions are overlapped between main scanning passes, but the complexity of printing control increases
Solution Approach 1:
Instead of complex overlap printing control, the patent simplifies the approach by changing the sub-scanning distance parameter based on gap measurements. This single parameter adjustment achieves banding reduction without requiring complex coordination of overlapping print regions
Solution Approach 2:
The patent extracts the essential control element from complex overlap printing and focuses solely on adjusting the sub-scanning distance. By isolating this single critical parameter, the system achieves banding reduction with simpler control logic
Data Source
AI summary
A printing control device is for a printing unit that is capable of adjusting a gap g between a recording head and a platen and performs main scanning to move the recording head in the main scanning direction with respect to the print substrate and sub-scanning to move the print substrate in a sub-scanning direction relative to the recording head. The printing control device includes a sub-scanning control unit that controls sub-scanning so that a first sub-scanning distance in a case in which the gap g is a first gap is shorter than a second sub-scanning distance in a case in which the gap g is a second gap broader than the first gap, in the sub scanning which corresponds to pseudo-band printing scheme and which is sub-scanning of a longer distance than a pitch of the nozzles of the nozzle line in the sub-scanning direction.