Inkjet Nozzle Compensation via Luminance Feedback
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Solution Overview
Problem
Inkjet printing apparatuses face challenges in accurately correcting print image defects caused by ejection defect nozzles, leading to density unevenness and suboptimal print quality.
Innovation Solution
A compensation coefficient determination method that sets divided regions with comparison areas and a normal region, applies provisional compensation coefficients, generates compensation coefficient calculation chart data, and calculates the actual compensation coefficient based on imaging data and luminance differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If alternative droplet ejection and shading correction process are performed, then ejection defect correction is achieved, but manufacturing precision is insufficient
Solution Approach 1:
The patent changes the parameter of compensation coefficient from a single fixed value to multiple provisional coefficients (K coefficients) that are systematically varied. By printing test charts with different provisional compensation coefficients and measuring the actual luminance values, the system determines the optimal compensation coefficient that achieves the target luminance, thereby improving print image defect correction accuracy
Solution Approach 2:
The patent introduces a feedback mechanism where the actual luminance values of printed test charts are measured and compared with target luminance values. Based on this feedback, the system calculates the difference and determines the optimal compensation coefficient, creating a closed-loop control system that continuously improves correction accuracy
2Manufacturing precision
If multiple provisional compensation coefficients are tested, then correction accuracy is improved, but productivity decreases
Solution Approach 1:
The patent segments the compensation coefficient determination process into distinct phases: (1) generating multiple provisional compensation coefficients, (2) printing test charts with these coefficients, (3) measuring actual luminance values, and (4) determining the optimal coefficient. This segmentation allows the system to perform comprehensive testing when needed while maintaining fast printing speed for normal production work
Data Source
AI summary
A tentative defective nozzle is set for each of K comparison regions associated with K provisional compensation coefficients different from each other. K pieces of sample image data are extracted from a captured image of a compensation coefficient calculation chart obtained by performing an ink amount compensation process on predetermined image data while applying the K provisional compensation coefficients to the K comparison regions. A function representing a correspondence relationship between a coefficient value and a luminance difference between a measured luminance value and a target luminance value is generated based on the K pieces of sample image data. A compensation coefficient to be actually applied to the ink amount compensation process is calculated using the function.