Tone Correction for Photoreceptor Spot Diameter Non-Uniformity
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Solution Overview
Problem
Existing electrophotographic image forming systems face challenges in achieving uniform spot diameters on a photoreceptor surface due to miniaturization and cost reduction efforts, leading to inplane uneven density and tone characteristic variations, which result in suboptimal image quality and increased correction residuals.
Innovation Solution
An image processing apparatus that holds tone correction properties corresponding to various spot diameters and selects the appropriate correction property based on the spot diameter for each pixel, generating tone correction data to correct for inplane uneven density while minimizing correction residuals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If lens characteristics are simplified for miniaturization or cost reduction, then device complexity and manufacturing cost are reduced, but spot diameter uniformity deteriorates causing inplane uneven density
Solution Approach 1:
The patent applies parameter changes by creating multiple tone correction tables corresponding to different spot diameter conditions. Instead of modifying the optical system, the invention changes the correction parameters to adapt to varying spot diameters caused by simplified lens characteristics, thereby maintaining image quality despite manufacturing constraints
Solution Approach 2:
The patent implements local quality by applying different tone correction properties to different regions of the image based on local spot diameter characteristics. The correction unit selects appropriate tone correction tables according to the specific spot diameter at each pixel position, enabling localized compensation for non-uniform spot diameters across the photoreceptor surface
2Manufacturing precision
If the number of tone correction tables is increased to suppress inplane uneven density, then correction precision is improved, but memory requirements and processing complexity increase
Solution Approach 1:
The patent uses parameter changes by organizing tone correction tables according to spot diameter parameters. Instead of using a large number of tables for all possible positions, the invention categorizes correction tables by spot diameter size, allowing the system to select appropriate tables based on the actual spot diameter measured or estimated for each pixel, thereby reducing the total number of tables needed while maintaining correction effectiveness
Solution Approach 2:
The patent applies dynamics by making the tone correction table selection adaptive rather than static. The correction unit dynamically selects the appropriate tone correction table based on the spot diameter at each pixel position, enabling the system to use only the necessary number of tables for the actual operating conditions rather than maintaining a fixed large set of tables for all possible scenarios
Data Source
AI summary
The present invention performs inplane uneven density correction that suppresses a number of tone correction properties and has few correction residuals. Accordingly, a holding unit of an apparatus of the present invention holds a plurality of tone correction properties respectively corresponding to a plurality of spot diameters that divide a range of a spot diameter of a light exposed on a surface of a photoreceptor by a predetermined interval. In addition a setting unit sets a tone correction property selected from the plurality of tone correction properties based on a spot diameter on the photoreceptor for a pixel corresponding to pixel data C. A correction unit corrects the pixel data C based on the set tone correction property, to generate tone correction data Cc.