Color Misregistration Detection in Image Forming Systems
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Solution Overview
Problem
Existing image forming systems face challenges in accurately detecting and adjusting for color misregistration due to variations in the speed of the transfer belt, such as eccentricity of the drive roller, slippage, shocks, and changes in load, which affect the accuracy of optical sensors in correcting scanning position and alignment.
Innovation Solution
An image forming system with multiple image carriers, an optical writing unit, a transfer member, a rotation detector, a belt controller, and an image detector that calculates misregistration based on detection data to adjust scanning line positions, curves, and inclinations, using a controller to correct relative misregistration between adjacent image carriers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical sensors are used to detect image positions for correcting color misregistration, then scanning position adjustments can be made, but detection accuracy is degraded due to transfer belt speed variations
Solution Approach 1:
A mark detection unit is introduced as an intermediary component that detects marks formed on the transfer belt at specific positions. This intermediary detection mechanism provides reference information about transfer belt position and speed variations, which is then used to correct the images formed on image carriers, thereby resolving the accuracy degradation caused by speed variations.
Solution Approach 2:
The system implements a feedback mechanism where the mark detection unit continuously monitors the transfer belt position and provides detection results to the controller. The controller uses this feedback information to calculate speed variations and adjust the imaging process accordingly, compensating for the speed variations that would otherwise degrade detection accuracy.
2Manufacturing precision
If the distance from transfer position to optical sensor is set as integer multiple of travel distance, then eccentricity-related misregistration is removed, but other speed variation factors remain undetected
Solution Approach 1:
Marks are pre-formed on the transfer belt at specific positions (such as one-quarter and three-quarter points of the travel distance) before the imaging process. These pre-positioned marks serve as reference points that allow the system to detect speed variations occurring at different phases of the transfer belt rotation, providing information that would otherwise be lost even when eccentricity-related misregistration is compensated.
3Measurement precision
If multiple marks are formed on transfer belt at different positions, then comprehensive speed variation detection is achieved, but system complexity increases
Solution Approach 1:
The mark detection unit is designed with multi-functionality to detect multiple types of speed variations using a single integrated system. By detecting marks at different positions on the transfer belt and analyzing their timing and position information, the system can comprehensively detect various speed variation factors (eccentricity, slippage, shocks, load changes) without requiring separate detection systems for each type of variation.
Data Source
AI summary
An image forming system, in which a method of detecting a misregistration of a color image is performed, includes multiple image carriers, an optical writing unit, a transfer member extended by a drive roller and at least one driven roller, a rotation detector, a roller driving unit, a belt controller, an image detector configured to detect the images formed on the surface of the transfer member and obtain detection data, and a controller configured to calculate an amount of misregistration and correct relative misregistration of a scanning line between the image carriers based on a result of the calculation. In the image forming system, a distance from a transfer position to a detection position is an integer multiple of a travel distance of the transfer member during one revolution of the at least one driven roller.