Duplex Image Position Correction for Sheet Displacement
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Solution Overview
Problem
Existing image forming apparatuses face challenges in maintaining image quality and productivity during duplex printing, as they do not adequately correct for lateral sheet displacement between the first and second surfaces, leading to increased shift amounts and reduced image quality.
Innovation Solution
An image forming apparatus with a detection system that adjusts the position of the sheet in the width direction for both the first and second surfaces, using a control mechanism to move the sheet to precise image positions based on edge position detection, thereby correcting skew and displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the image forming apparatus uses a detection result of an edge portion of a preceding sheet for determining the image formation position of a following sheet, then the image formation position can be corrected in advance, but the shift amount for the second surface increases due to lateral displacement during duplex conveyance
Solution Approach 1:
The detection portion detects the edge position of the sheet in advance during the duplex conveyance process, and the control portion calculates the lateral displacement amount before the sheet reaches the transfer portion again. This preliminary detection and calculation allows the system to pre-determine the corrected image formation position for the second surface, compensating for lateral displacement that occurs during conveyance.
Solution Approach 2:
The system uses the detection result of the edge portion position as feedback to dynamically adjust the image formation position. The control portion calculates the lateral displacement based on the detected edge position and applies this feedback information to correct the image formation position on the photoconductor, ensuring accurate image placement despite sheet displacement during duplex printing.
2Device complexity
If the image forming apparatus does not change the image formation position between the first surface and the second surface, then the device complexity is reduced, but the shift amount increases lowering image quality
Solution Approach 1:
The image formation position is made dynamic rather than static. The control portion adjusts the image formation position on the photoconductor based on the detected lateral displacement of the sheet. For the second surface, the system dynamically calculates and applies a position offset to compensate for the lateral displacement that occurred during duplex conveyance, ensuring accurate image placement without requiring complex mechanical adjustments.
3Productivity
If the sheet is conveyed during duplex printing without position correction, then the conveyance process is simple and fast, but lateral displacement occurs reducing image quality
Solution Approach 1:
Instead of using complex mechanical systems to physically adjust or restrain the sheet during conveyance, the patent substitutes a detection and calculation system. The detection portion optically detects the edge position, and the control portion calculates the lateral displacement, then applies this information to correct the image formation position. This non-contact, information-based approach maintains fast conveyance speed while achieving position accuracy.
Data Source
AI summary
An image forming apparatus includes an image bearing member and an image forming portion configured to form first and second toner images on the image bearing member. A control portion controls the image forming portion such that a first toner image is formed on a first image position of the image bearing member, and a second toner image is formed on a second image position of the image bearing member. The sheet moves to a first sheet position corresponding to the first image position based on a first detection position before the first toner image is transferred onto a first surface of the sheet and moves, after being inverted, to a second sheet position corresponding to the second image position based on a second detection position before the second toner image is transferred onto a second surface of the sheet.