Inkjet Printhead Nozzle Failure Detection via Differential Analysis
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Solution Overview
Problem
Conventional inkjet printing systems face challenges in accurately detecting and addressing discharge failure nozzles due to varying detection sensitivity of CCD line sensors, leading to image quality degradation.
Innovation Solution
A printing apparatus and method that employs a differential analysis process using inspection patterns to reliably identify discharge failure nozzles, even with non-constant sensor sensitivity, through the calculation of peak difference values and accumulated values, enabling effective recovery and supplement operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a CCD line sensor is used to detect inspection patterns for identifying discharge failure nozzles, then detection capability is provided, but varying detection sensitivity across CCD elements causes measurement errors and reduces detection accuracy
Solution Approach 1:
The patent applies feedback by calculating the average density value from multiple inspection patterns and using this average as a reference to determine discharge failure nozzles. This feedback mechanism compensates for varying CCD element sensitivity by comparing individual measurements against the averaged reference, thereby maintaining detection reliability despite sensor variability
Solution Approach 2:
The patent performs preliminary action by pre-calculating average density values from multiple inspection patterns before final nozzle identification. This preliminary averaging process establishes a corrected reference that accounts for CCD sensitivity variations, enabling accurate discharge failure detection in the subsequent evaluation step
2Productivity
If accumulated density data is compared with a threshold to specify discharge failure nozzles, then discharge failure detection is enabled, but non-constant sensor sensitivity causes false specifications and degrades image quality
Solution Approach 1:
The patent applies parameter changes by transforming the raw density data into average density values through repeated measurement and averaging. This parameter transformation converts variable sensor readings into a stabilized reference value, enabling accurate threshold comparison for nozzle specification while maintaining high detection efficiency
Solution Approach 2:
The patent uses feedback by establishing a reference level through averaging multiple measurements and using this reference to guide the threshold comparison process. This feedback loop ensures that nozzle specification accuracy is maintained despite sensor variability, while the automated process preserves high detection efficiency
Data Source
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AI summary
A printing apparatus includes a printhead (14) configured to array a nozzle array in which a plurality of nozzles for discharging ink are arrayed in the first direction, a reading means for reading, as a plurality of luminance values aligned in a nozzle arrayed direction, an inspection pattern (200) formed by discharging ink from the plurality of nozzles of the printhead, a calculation means for calculating a plurality of difference values each by calculating a difference between two luminance values spaced apart by a predetermined number of luminance values, and an analysis means for analyzing an ink discharge state in the plurality of nozzles based on the plurality of difference values.