Printhead Mask Selection for Drying Risk in Special Color Ejection
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Solution Overview
Problem
Liquid ejecting apparatuses face ejection defects due to the special colors, as the use frequency of the special colors is lower than the use frequency of the process colors, and the drying of the special colors, and the drying of the nozzle in the joint area between the first ejection head and the second ejection head can be reduced by changing the mask depending on the drying risk.
Innovation Solution
The apparatus includes a first and second ejection head with overlapping nozzles in a joint area, a controller to assess drying risk, and a mask selection process to reduce the occurrence of ejection defect by selecting one mask depending on the drying risk, and a mask selection process to reduce the occurrence of the nozzle defect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the use frequency of special color inks is reduced, then the productivity is improved, but the reliability deteriorates due to ejection defects from drying nozzles
Solution Approach 1:
The patent applies preliminary action by performing mask selection based on drying risk assessment before the actual printing process. The controller evaluates the drying risk of liquid in nozzles and pre-selects an appropriate mask that prevents ejection defects, ensuring reliable operation before productivity concerns arise.
Solution Approach 2:
The patent changes the parameter of nozzle usage pattern by selecting different masks with varying use-permission rates. This allows dynamic adjustment of which nozzles are active based on drying risk, thereby maintaining reliability while optimizing productivity through appropriate parameter selection.
2Reliability
If the mask is changed depending on drying risk, then the reliability is improved by reducing ejection defects, but the device complexity increases due to multiple masks and selection processes
Solution Approach 1:
The patent applies dynamics by making the mask selection dynamic rather than static. The controller dynamically selects masks based on real-time drying risk assessment, allowing the system to adapt to changing conditions while maintaining a manageable set of predefined mask options.
Solution Approach 2:
The patent implements feedback through the drying risk assessment process. The controller evaluates the state of nozzles and uses this feedback information to select the appropriate mask, creating a closed-loop system that maintains reliability without requiring complex manual intervention.
3Productivity
If the first use-permission rate increases toward the first side, then the productivity is improved, but the drying risk increases in that region
Solution Approach 1:
The patent applies local quality by allowing different use-permission rates for different regions (first side vs. second side) of the nozzle array. The mask selectively permits usage of specific nozzles based on their drying risk, optimizing productivity in low-risk regions while protecting high-risk regions from drying defects.
Data Source
AI summary
A liquid ejecting apparatus includes: first and second ejection heads; a conveyor; a carriage; and a controller. The controller is configured to execute: a risk obtaining process of obtaining information on drying risk of a liquid; a mask selecting process of selecting one mask of a plurality of masks depending on the drying risk; and a printing process. Each of the plurality of masks defines first and second ratios. The first ratio is a ratio of increasing toward a first side in a conveyance direction of a first use-permission rate. The second ratio is a ratio of decreasing toward the first side in the conveyance direction of a second use-permission rate. The first ratio is different from each other among the plurality of masks, and the second ratio is different from each other among the plurality of masks.