Inkjet Head Defect Correction Parameter Selection Chart
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Solution Overview
Problem
Conventional methods for correcting image formation defects caused by defective recording elements in inkjet heads, such as ejection failure nozzles, face challenges in accurately measuring correction parameters due to human visual characteristic disparities and varying scanner resolutions, leading to inconsistent correction results across different head modules and being influenced by positional errors and landing interference.
Innovation Solution
A defective recording element correction parameter selection chart is used, which includes reference and measurement patches to determine optimal correction parameters by varying the defective recording element correction parameter in a continuous or stepwise fashion, allowing for accurate measurement and selection of the optimal parameter that minimizes image formation defects, while accounting for factors like landing interference patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ejection failure correction methods are used to increase the density of image formation by adjacent nozzles, then the visibility of white stripes is reduced, but measurement accuracy declines due to human visual characteristic disparities and varying scanner resolutions
Solution Approach 1:
The patent changes the measurement parameter from scanner tone values to human visual perception-based evaluation. It introduces a visual evaluation chart that allows direct human assessment of correction quality, eliminating the mismatch between scanner measurements and human visual characteristics. The correction parameter is optimized based on human visual perception rather than scanner readings.
2Reliability
If the ejection failure correction parameter is increased to strengthen image formation by correction nozzles, then white stripe visibility is reduced, but black stripes are formed due to over-correction
Solution Approach 1:
The patent implements a feedback mechanism where the correction parameter is optimized based on visual evaluation of the output chart. Human evaluators assess the correction quality and provide feedback on whether white stripes are visible or if black stripes appear due to over-correction. This feedback loop allows for precise tuning of the correction parameter to achieve optimal correction without over-correction.
3Ease of manufacture
If the same ejection failure correction parameter is applied to all head modules, then manufacturing simplicity is maintained, but correction visibility varies between head modules
Solution Approach 1:
The patent applies local quality by allowing different ejection failure correction parameters to be determined for different head modules. Each head module undergoes separate measurement and evaluation, resulting in module-specific correction parameters. This ensures that each module receives optimized correction tailored to its specific characteristics, improving correction consistency across all modules while maintaining a standardized evaluation process.
4Device complexity
If test pattern output is used to measure ejection failure correction parameter, then measurement process is simplified, but image non-uniformities occur due to positional error and ejection non-uniformities
Solution Approach 1:
The patent creates a visual evaluation chart that copies the actual image formation conditions and defects. Instead of using simplified test patterns that may not represent real conditions, the evaluation chart reproduces the actual correction results with all their nuances, allowing human evaluators to assess correction quality under realistic conditions. This copying approach maintains measurement simplicity while improving accuracy by reflecting actual operating conditions.
Data Source
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Figure 3(a)~3(d)
AI summary
A defective recording element correction parameter selection chart (5) which is output by an image forming apparatus (100) that performs image formation on a recording medium (124) by a plurality of recording elements (253) included in a recording head (172M, 172K, 172C, 172Y, 250) while conveying at least one of the recording head (172M, 172K, 172C, 172Y, 250) and the recording medium (124) so as to cause relative movement between the recording head (172M, 172K, 172C, 172Y, 250) and the recording medium (124), the chart (5) being used, in a case where there is at least one defective recording element (NA_j, NB_k, Nz_A, Nz_B, Nz_a, Nz_b, Nz_c, Nz_d) which is not able to perform recording among the plurality of recording elements (253), in order to determine a defective recording element correction parameter (Pi) expressing an amount of correction for correcting image formation defects caused by the at least one defective recording element (NA_j, NB_k, Nz_A, Nz_B), with image formation by a recording element (253) other than the at least one defective recording element (NA_j, NB_k, NZ_A, NZ_B, NZ_a, NZ_b, NZ_c, NZ_d), includes: a reference patch (Iref) constituted by a uniform image which is an image formed on a region of the recording medium (124) with a uniform density based on a constant tone; and at least one measurement patch (Iimeas(Pi)) in which a state after correction using the amount of correction corresponding to a candidate value of the defective recording element correction parameter (Pi) which expresses the amount of correction is reproduced in a state that one or more of the recording elements (253) which have formed the reference patch (Iref) are set to be in a non-recording state, the candidate value of the defective recording element correction parameter (Pi) being applied to an image formation portion which is formed by a recording element that carries out recording in a vicinity of a non-recording position of the one or more of the recording elements (253) which have formed the reference patch (Iref) and have been set to be in the non-recording state.