Bidirectional Printing Color Shift Compensation
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Solution Overview
Problem
High-speed bidirectional band printing with vertical array heads results in color unevenness due to timing differences in ink droplet ejection during color bidirectional printing, affecting the quality of printed images.
Innovation Solution
A printing device and method that includes a recording head with a black nozzle row and color nozzle groups aligned along the black nozzle row, featuring a control section that compensates for color shifts by forming reference patches and patches at different timing differences, allowing for the selection of a color shift compensation patch to adjust recording density ratios and correct for timing-related color unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If bidirectional printing is performed with a vertical array head to achieve high-speed color printing, then printing speed is improved, but color unevenness occurs due to timing differences in ink droplet ejection
Solution Approach 1:
The control section pre-calculates and determines the optimal recording density ratio for each color nozzle group based on its position in the main scanning direction before actual printing. This preliminary adjustment compensates for the inherent timing differences in bidirectional printing, allowing the printer to maintain color uniformity while operating at high speeds without requiring real-time correction during the printing process
Solution Approach 2:
Different recording density ratios are applied to different color nozzle groups based on their specific positions in the main scanning direction. The control section allocates position-dependent recording density ratios to each color nozzle group, ensuring that each nozzle group compensates for its specific timing characteristics. This localized adjustment resolves color unevenness while preserving high-speed bidirectional printing performance
2Productivity
If color nozzle groups eject ink droplets in both forward and return paths, then printing efficiency is improved, but timing differences cause color shifts in the printed image
Solution Approach 1:
The control section dynamically adjusts the recording density ratio parameter for each color nozzle group based on its position in the main scanning direction. By changing this parameter according to position, the system compensates for timing differences that occur when different color nozzle groups eject ink droplets at different times during bidirectional printing, thereby maintaining color accuracy while preserving printing efficiency
Data Source
AI summary
A recording head includes a plurality of color nozzle groups in which the colors of color ink droplets ejected in a forward path and in a return path in bidirectional printing are different from each other with respect to a band region. A compensation section forms a reference patch on the recording medium by ejecting the first and second color ink droplets in a predetermined recording density ratio at a reference timing difference with respect to an ejection timing difference between first color ink droplets from a first color nozzle group and second color ink droplets from a second color nozzle group, which are generated depending on the position in the band region in the main scanning direction, forms a plurality of first patches on the recording medium by ejecting the first and second color ink droplets in a plurality of different recording density ratios at a first timing difference, and compensates for the color shift due to the timing difference based on a recording density ratio corresponding to a first color shift compensation patch selected from the plurality of first patches to form a print image.