Image Density Correction Using Multi-Tone Pattern Alignment
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Solution Overview
Problem
Existing image forming apparatuses face challenges in achieving uniform image density due to component tolerances and assembly issues, leading to uneven light distribution and image quality, with existing correction methods being prone to errors and requiring multiple test charts, which can lower accuracy and prolong adjustment times.
Innovation Solution
An image forming apparatus with a conversion unit, image forming units, conveyance unit, and controller that forms and aligns pattern images with varying tones in a specific direction, allowing for data-driven correction of density variations and tone characteristics on a single sheet, reducing the need for multiple test charts and shortening the adjustment period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If density patterns vary in density in a stepwise manner in the sub-scanning direction, then tone characteristics can be corrected, but many image formation regions are necessary in the sub-scanning direction requiring multiple separate sheets
Solution Approach 1:
The patent combines multiple functions (density correction and tone characteristic correction) into a single test chart by forming pattern images of different colors (cyan, magenta, yellow) with different tones on the same sheet. This merging eliminates the need for multiple separate sheets while maintaining comprehensive correction capabilities.
Solution Approach 2:
The patent changes the arrangement dimension of density patterns from the sub-scanning direction to the main-scanning direction. By aligning pattern images of different tones in the main-scanning direction rather than stacking them in the sub-scanning direction, the patent achieves comprehensive tone coverage on a single sheet without requiring excessive area in the sub-scanning direction.
2Ease of operation
If the central position of the image in the main-scanning direction is used as the reference density, then correction can be performed, but erroneous correction may occur when an image defect has occurred at the central position
Solution Approach 1:
The patent extracts the reference density measurement from the central position and relocates it to the left end position in the main-scanning direction. This extraction of the reference point from the potentially defective central region eliminates the risk of erroneous correction while maintaining the simplicity of the correction operation.
3Quantity of substance
If the number of sheets of the test chart is reduced through downsizing of the density patterns, then the number of sheets is reduced, but the reading accuracy may be lowered
Solution Approach 1:
The patent resolves the space-accuracy contradiction by changing the spatial arrangement from sub-scanning direction stacking to main-scanning direction alignment. This dimensional reorganization allows sufficient pattern size for accurate reading while fitting all patterns on a single sheet through efficient use of the main-scanning direction space.
Data Source
AI summary
An image forming apparatus controls a first image forming unit and a second image forming unit to form a plurality of pattern images. The plurality of pattern images includes a first pattern image formed by the first image forming unit, a second pattern image formed by the second image forming unit, a plurality of third pattern images that are formed by the first image forming unit and have different tones from one another, and a plurality of fourth pattern images that are formed by the second image forming unit and have different tones from one another. The image forming apparatus obtains data that has been output from a sensor and is related to the plurality of pattern images, and generates the conversion condition based on the data.