Inkjet Printer Nozzle Defect Compensation via Pixel Density Adjustment
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Solution Overview
Problem
Inkjet printers face issues with dot omission due to clogged nozzles, leading to image quality deterioration and density unevenness, as defective nozzles fail to eject ink properly, causing halftone dots to be misplaced and resulting in visible streaks and density variations.
Innovation Solution
An inkjet printer system with a print control section that identifies defective nozzles and adjusts the density of adjacent pixels to compensate for dot omissions, increasing the density of second pixels adjacent to the first pixels printed by the defective nozzle and reducing the density of third pixels, thereby minimizing the visibility of dot omissions and density unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the positions of dots are changed to make dot omission less noticeable, then the visibility of dot omission is reduced, but density unevenness occurs due to overlapping dots causing streaks and visual defects
Solution Approach 1:
The patent applies local quality by differentiating the treatment of pixels based on their position relative to the defective nozzle. Second pixels (adjacent to defective pixels) have their density increased to compensate for missing dots, while third pixels (adjacent to second pixels) have their density reduced to prevent overlapping artifacts. This localized differentiation resolves the contradiction by addressing dot omission visibility in affected areas without causing density unevenness in broader regions.
2Productivity
If ink ejection is performed from all nozzles using normal image data, then printing speed is maintained, but dot omission occurs due to defective nozzles causing image quality deterioration
Solution Approach 1:
The patent implements preliminary action by generating corrected image data before the actual printing process. The image data is pre-processed to compensate for known defective nozzle positions, adjusting pixel densities in advance. This allows the printer to maintain normal printing speed without retraction while ensuring that defective nozzles do not cause dot omission, as the compensation is already embedded in the image data.
3Manufacturing precision
If the density of second pixels is increased to compensate for dot omission, then the visibility of dot omission is reduced, but density unevenness and streaks become visually confirmed
Solution Approach 1:
The patent applies the counterweight principle by introducing a compensatory reduction in density for third pixels to balance the density increase in second pixels. The density increase in second pixels compensates for the dot omission from defective nozzles, while the subsequent density reduction in third pixels counteracts the potential for overlapping and streak formation. This dual adjustment creates a balanced compensation strategy that addresses the harmful effects of both under-compensation and over-compensation.
Data Source
AI summary
An inkjet printer includes a print head, a nozzle position 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 of the plurality of nozzles that exhibits defective ejection of the ink. The print control section is configured to eject the ink from the plurality of nozzles based on image data. The print control section is configured to determine a density of second pixels, which are positioned adjacent to first pixels to be printed by the first nozzle that was specified, and a density of third pixels, which are positioned adjacent to the second pixels except the first pixels, based on the image data, and to correct to increase the density of the second pixels and to reduce the density of the third pixels.