Inkjet Print Head Scanning Direction Control for Color Gap Reduction
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Solution Overview
Problem
Bidirectional printing in inkjet printers causes color gaps due to differences in ink overlapping orders during forward and reverse scanning directions, leading to perceived color discrepancies in printed images.
Innovation Solution
An image processing apparatus that determines the scanning direction for each band image based on color conditions, ensuring that the same direction is maintained for band images with color-gap-causing pixels and alternates directions for those that do not satisfy the conditions, thereby reducing conspicuous color gaps and improving printing speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If bidirectional printing is performed to improve printing speed, then productivity increases, but color gaps occur due to different ink overlapping orders in forward and reverse directions
Solution Approach 1:
The patent dynamically determines the scanning direction for each band image based on color conditions, allowing the printing system to adaptively switch between forward and reverse directions. This dynamic approach enables bidirectional printing to maintain high speed while preventing color gaps by choosing the appropriate scanning direction for each specific band image.
Solution Approach 2:
The patent applies different scanning directions to different band images based on their specific color characteristics. By evaluating color conditions locally for each band image and determining the optimal scanning direction individually, the system ensures color uniformity in specific regions while maintaining overall printing speed through bidirectional operation.
2Manufacturing precision
If the same scanning direction is determined for all band images to prevent color gaps, then color uniformity is maintained, but printing speed decreases due to unnecessary direction changes
Solution Approach 1:
The patent applies bidirectional printing selectively to only those band images that meet specific color conditions, rather than forcing unidirectional printing for all bands. This partial application of bidirectional printing prevents color gaps in critical regions while allowing speed optimization in regions where color uniformity is less sensitive, thereby improving overall printing speed without sacrificing necessary color quality.
3Productivity
If bidirectional printing is performed without direction determination based on color conditions, then printing speed is maximized, but conspicuous color gaps appear in the printed image
Solution Approach 1:
The patent implements a feedback mechanism where the controller evaluates color conditions for each band image based on the ink overlapping order and determines the appropriate scanning direction accordingly. This feedback loop allows the system to automatically adjust scanning directions to prevent conspicuous color gaps while maintaining high printing speed through bidirectional operation.
Solution Approach 2:
The patent determines the scanning direction for each band image in advance based on predicted color conditions and ink overlapping orders, before actual printing occurs. This preliminary determination prevents conspicuous color gaps by pre-planning the optimal scanning direction for each band, allowing bidirectional printing to proceed at maximum speed without causing color uniformity issues.
Data Source
AI summary
An image processing apparatus repeats an ejection process for ejecting color materials by moving a print head in one of a forward direction and a reverse direction in a main scanning direction, and a moving process for moving a print medium in a sub-scanning direction. In a case where an L-th band image satisfies both of a first color condition and a second color condition, a direction of the ejection process is determined to be the same direction as the direction of moving of the print head in the ejection process for another band image including a predetermined number or more of pixels. Where the L-th band image does not satisfy at least one of the first color condition and the second color condition, the direction process of the ejection process is determined to be an opposite direction to moving of the print head in an (L−1)-th ejection process.