Image Forming Apparatus Scanning Line Distortion Correction
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Solution Overview
Problem
Electrophotographic image forming apparatuses face color misregistration issues due to scanning line distortion, which existing digital correction methods struggle to address efficiently, leading to detection errors and increased costs or processing time.
Innovation Solution
An image forming apparatus with a correcting unit that adjusts image data in the sub scanning direction based on stored displacement or distortion characteristics of the scanning line, ensuring positional displacement is less than half the distance between neighboring scanning lines, thereby correcting scanning line distortions and reducing detection errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If digital correction of image data is performed to correct scanning line distortion, then scanning line distortion is corrected, but processing time increases when using software
Solution Approach 1:
The patent stores distortion characteristics of the scanning line in advance and uses this pre-stored data to correct image data, eliminating the need for real-time complex calculations during image formation, thus reducing processing time while maintaining correction accuracy
Solution Approach 2:
The patent changes the approach from calculating distortion correction in real-time to using pre-stored distortion characteristic data, transforming the correction process into a simpler data retrieval and application operation that reduces processing time
2Loss of time
If hardware is used to perform distortion correction, then processing time is reduced, but circuit size increases and costs increase
Solution Approach 1:
The patent uses software-based correction utilizing pre-stored distortion characteristic data instead of implementing complex hardware circuits, achieving fast processing through efficient data handling while avoiding the cost and complexity of dedicated hardware correction circuits
Solution Approach 2:
The patent replaces potential hardware correction mechanisms with a software-based approach that uses pre-stored distortion data, achieving the same functional result with lower cost and simpler implementation
3Loss of time
If the division unit in the main scanning direction is made large, then processing time using software is reduced and circuit size is reduced, but displacement from the reference line increases
Solution Approach 1:
The patent pre-stores distortion characteristics that account for scanning line displacement, allowing the use of larger division units without sacrificing precision, since the distortion data is already prepared to compensate for reference line deviations
Solution Approach 2:
The patent changes the correction approach by using pre-stored distortion characteristic data that incorporates reference line information, enabling larger division units to be used while maintaining positioning accuracy through the pre-computed distortion compensation
4Measurement precision
If color misregistration detection pattern images are formed on the intermediate transfer member, then color misregistration can be detected, but detection errors occur when scanning line is distorted
Solution Approach 1:
The patent pre-corrects the image data for distortion before forming the color misregistration detection pattern images, ensuring that the patterns are formed with accurate scanning lines, which then enables reliable detection without errors caused by distortion
Solution Approach 2:
The patent applies preliminary distortion correction to counteract the harmful effect of scanning line distortion before the detection process, preventing detection errors from occurring in the first place by eliminating the distortion that would cause measurement errors
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 effectively reduces detection errors of color misregistration by accurately aligning image data with reference lines, improving the precision of color registration without significantly increasing hardware costs or processing time.
Implementation Method 1
scans a photosensitive member with a light beam to form a latent image on the photosensitive member
Implementation Method 2
develops the latent image on the photosensitive member
Implementation Method 3
transfers the developed image to an image bearing member
Data Source
AI summary
An image forming apparatus includes a profile storage section that stores distortion characteristic of a scanning line, a correcting section that corrects image data by lines in the sub scanning direction, and a registration sensor that detects a pattern image for detecting color misregistration amounts in a sub scanning direction of images formed on an intermediate transfer member. When the pattern image is formed, the distortion correcting section shifts image data of the pattern image by lines in the sub scanning direction so that, with reference to a detection position of the registration sensor, a positional displacement amount of the pattern image in the sub scanning direction becomes less than or equal to ½ of a scanning-line distance, in accordance with a positional displacement amount of the scanning line in the sub scanning direction at a detection position of the registration sensor along a main scanning direction.