Inkjet Printer Nozzle Defect Compensation via Dot Size Adjustment
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Solution Overview
Problem
Inkjet printers face issues with dot omission due to clogged nozzles, leading to image quality deterioration, as defective nozzles result in uneven densities and noticeable gaps between halftone dots, which existing methods struggle to fully mitigate.
Innovation Solution
The inkjet printer adjusts the size of dots printed by adjacent nozzles to overlap and compensate for defective nozzles, with the print control section modifying dot sizes based on image data and dither mask thresholds to minimize dot omission and density unevenness, employing a configuration where nozzles are positioned to intersect with the print substrate's feed direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the positions of dots are changed to compensate for defective nozzles, then dot omission becomes less noticeable, but density unevenness occurs due to overlapping dots
Solution Approach 1:
The patent applies local quality by differentiating the treatment of dots based on their position relative to defective nozzles. Dots from nozzles adjacent to defective nozzles are enlarged to compensate for missing dots, while dots from nozzles not adjacent to defective nozzles maintain their original size. This localized adjustment ensures that compensation occurs only where needed, preventing unnecessary density unevenness in other areas of the printed image.
2Manufacturing precision
If dot size is increased to compensate for defective nozzles, then dot omission visibility is reduced, but density unevenness and streaks become more noticeable
Solution Approach 1:
The patent implements local quality by selectively enlarging only those dots that are positioned adjacent to defective nozzles, while maintaining the original size of dots from non-adjacent nozzles. This localized differentiation ensures that compensation for dot omission occurs precisely where needed, preventing the creation of visible streaks and excessive density variations that would result from uniformly enlarging all dots across the entire image.
Data Source
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Figure 3A~3B
AI summary
An inkjet printer includes a print head, a nozzle position specifying section and a print control section. The print head includes a plurality of nozzles to eject ink. The nozzle position specifying section is configured to specify a position of a first nozzle that exhibits defective ejection. The print control section is configured to print dots in a plurality of sizes. The print control section is configured to change a dot size of a dot to be printed by a second nozzle, which is positioned adjacent to the first nozzle, to a larger size than a dot size specified in an image data, and to change a dot size of a dot to be printed by a third nozzle, which is positioned adjacent to the second nozzle, to a smaller size than the dot to be printed by the second nozzle after the change.