Printing Apparatus Tone Correction Using Preceding Page Density Feedback
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Solution Overview
Problem
Existing tone correction techniques in printing face delays due to sheet circulation and conveyance paths, leading to inconsistent image quality across pages, especially when handling multiple print jobs with small page counts.
Innovation Solution
A printing apparatus that generates tone-corrected page images by combining a patch for tone correction with each page image, measures the patch density using a color measurement sensor, and stores reference values for each sheet type, allowing for real-time tone correction based on preceding page densities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If tone correction is performed by reading a tone correction patch printed on a sheet by a color measurement sensor and feeding back the results, then accurate suppression effect of tone variation is achieved, but feedback delay occurs in accordance with sheet circulation within a print engine and a conveyance path length
Solution Approach 1:
The patent applies preliminary action by performing tone correction for a subsequent page using the density value measured from the preceding page before the actual printing occurs. The correction value is calculated in advance and stored, so when the subsequent page is printed, the tone correction is already applied without waiting for feedback from the color measurement sensor. This eliminates the feedback delay while maintaining accurate tone variation suppression.
2Reliability
If the density reference value for suppressing the tone variation is reset for each print job, then tone correction is performed for each job, but a predetermined number of pages for which the tone correction is not performed occurs each time the print job is changed
Solution Approach 1:
The patent applies continuity of useful action by maintaining the density reference value across multiple print jobs instead of resetting it for each job. The system continuously updates the density reference value with each measurement, allowing tone correction to be applied without interruption even when print jobs are changed. This eliminates the blank period where tone correction is not performed, ensuring continuous tone variation suppression across all pages regardless of job transitions.
3Loss of time
If real-time tone correction is performed during print job processing, then feedback delay is reduced, but tone correction consistency across multiple print jobs with small page counts is compromised
Solution Approach 1:
The patent applies feedback by continuously updating the density reference value with each measurement from the color measurement sensor, even across print job boundaries. The system uses this updated reference value to calculate correction values for subsequent pages. This continuous feedback mechanism ensures that tone correction remains consistent and accurate across multiple print jobs with small page counts, while still achieving real-time correction by using the updated reference value immediately for the next page's correction.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces feedback delays while maintaining effective tone variation suppression across pages, even when handling multiple print jobs with small page counts, by continuously feeding back correction values specific to each sheet type.
Implementation Method 1
a measuring unit configured to measure density of the patch formed on a sheet by the printing unit
Data Source
AI summary
A printing apparatus includes an image forming portion which forms a chart image on a sheet conveyed from a sheet feeding deck, a color measure portion which performs color measurement by reading the chart image formed by the image forming portion, and one or more controllers including one or more processors and one or more memories. The one or more controllers are configured to generate correction data based on color measurement results by the color measurer portion and a reference value, and perform correction for target image data by using the generated correction data. The reference value is obtained by performing color measurement by the color measure portion and is registered in association with a type of sheet on which the chart image is formed, and in a case where the type of sheet on which the chart image is formed is changed, the reference value is updated.