Printing Device Shift Correction via Partial Value Selection
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Solution Overview
Problem
Conventional printing apparatuses face challenges in accurately correcting image shifts due to temporal variations in web paper transporting speed and printing timing, leading to excessive corrections and poor printing quality.
Innovation Solution
The printing apparatus employs a shift amount detecting chart that reflects variations in density peak positions, allowing the calculating device to determine correction values based on shift amounts smaller than the maximum absolute value, thereby preventing excessive corrections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If correction is made based on maximum shift amount from shift amount detecting chart, then shift correction is performed, but excessive correction occurs leading to poor printing quality
Solution Approach 1:
The patent applies partial action by intentionally selecting correction values that are smaller than the maximum detected shift amount. Instead of correcting for the full maximum shift, the system chooses correction values within a predetermined range that is less than the maximum shift amount, thereby avoiding excessive correction and maintaining printing quality.
Solution Approach 2:
The patent changes the parameter of correction value magnitude by introducing a predetermined range that limits the correction amount. The correction values are selected from this constrained range rather than using the full detected shift amount, effectively modifying the correction parameter to prevent quality degradation.
2Device complexity
If only shift amounts at a certain point in time are corrected, then correction process is simple, but temporal variations in shift amounts cannot be addressed
Solution Approach 1:
The patent applies preliminary action by pre-establishing a predetermined range of correction values before the correction process. This predetermined range is set in advance to account for temporal variations, allowing the system to handle time-varying shifts without complex real-time adjustments while maintaining reliability.
3Measurement precision
If correction values are based on maximum shift amount, then all shift variations are addressed, but excessive correction occurs within predetermined length
Solution Approach 1:
The patent deliberately uses partial action by selecting correction values that are less than the maximum shift amount. This partial correction approach ensures that corrections are applied only within acceptable limits, preventing quality degradation while still addressing the majority of shift variations within the predetermined length.
Data Source
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AI summary
A shift amount detecting chart is formed on web paper WP, and the shift amount detecting chart is photographed by an image pickup unit 17. An image processor 27 calculates shift amounts smaller than a maximum shift amount in absolute values as correction values based on a variation trace of density peak positions from image data corresponding to the shift amount detecting chart photographed by the image pickup unit 17. A controller 25 corrects printing timing with these correction values. Consequently, even when temporal variations occur to the shift amounts within a predetermined length, since the correction values are calculated based on the shift amounts smaller than the maximum shift amount in absolute values, an excessive correction can be prevented, thereby to improve printing quality.