Image Position Correction for Duplex Printing Across Contact States
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Solution Overview
Problem
Image forming apparatuses face challenges in maintaining accurate image forming positions on both the front and back surfaces during double-sided printing, particularly in tandem systems where the contact state between photosensitive drums and a transfer belt varies between color and monochrome modes, leading to errors in correction values.
Innovation Solution
The apparatus includes a mechanical mechanism to control the contact state between photosensitive members and an intermediate transfer member, with separate control states for color and monochrome modes, and a reading unit to adjust image forming positions based on test image readings, using different data sets for each state to ensure accurate positioning on both surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If three photosensitive drums other than black are separated from the transfer belt in monochrome mode, then abrasion is reduced and productivity is improved, but the tension of the transfer belt decreases and image forming position accuracy deteriorates
Solution Approach 1:
The patent applies dynamics by making the contact state between photosensitive drums and transfer belt variable rather than fixed. The mechanical mechanism dynamically adjusts the contact state based on printing mode (color or monochrome), allowing the system to adapt between high productivity in monochrome mode and stable tension in color mode, thereby resolving the contradiction between productivity and image forming position accuracy
2Manufacturing precision
If four photosensitive drums come in touch with the transfer belt in color mode, then the tension of the transfer belt increases and image forming position accuracy is maintained, but abrasion increases and productivity decreases
Solution Approach 1:
The system dynamically changes the contact configuration of photosensitive drums based on the printing mode. In color mode, all four drums contact the transfer belt to maintain stable tension and image forming position accuracy. In monochrome mode, three drums are separated to reduce abrasion and improve productivity. This dynamic adaptation resolves the contradiction between precision and productivity
3Measurement precision
If correction values are generated using a chart printed in monochrome mode, then the correction values reflect monochrome contact state, but they cause errors when used in color mode due to different tension conditions
Solution Approach 1:
The patent segments the correction values into mode-specific sets: monochrome mode correction values and color mode correction values. Each set is generated independently using charts printed in the corresponding mode, ensuring that the correction values accurately reflect the specific contact state and tension conditions of that mode. This segmentation resolves the contradiction by preventing the use of inappropriate correction values across different modes
Solution Approach 2:
The system changes the parameter of correction values based on the printing mode. Different correction values are selected and applied depending on whether the operation is in monochrome or color mode. This parameter change ensures that the correction values remain accurate and appropriate for each specific operating condition, resolving the contradiction between measurement precision and mode compatibility
Data Source
AI summary
An image forming apparatus is configured to, based on a reading result of a test image, generate data that is used to adjust image forming positions of toner images to be formed by an image forming unit, control an image forming position of a first toner image to be formed by the image forming unit in a first contact state based on first data, the first toner image being transferred to a first sheet, and control an image forming position of a second toner image to be formed by the image forming unit in a second contact state based on second data that is different from the first data, the second toner image being transferred to a second sheet, wherein a type of the second sheet is the same type as the type of the first sheet.