Sheet Position Correction in Duplex Printing Apparatus
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Solution Overview
Problem
Existing image forming apparatuses face challenges in maintaining accurate image positioning due to sheet conveyance errors, leading to positional deviations during image transfer, especially in duplex printing where front and back images may not align correctly.
Innovation Solution
The image forming apparatus incorporates a sheet conveying device with a pair of holding rollers and position detectors (CIS) that rotate and shift to correct lateral and angular displacements of the sheet, ensuring precise alignment before image transfer, using a combination of motors, gears, and encoders for accurate movement control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If sheet conveyance is performed without position correction, then the conveying process is simple and fast, but the image position on the sheet deviates from the desired position
Solution Approach 1:
The sheet position is corrected in advance during the conveyance process, before the image transfer occurs. The holding body adjusts the sheet position proactively, ensuring the image will be formed at the correct position without requiring post-correction mechanisms.
Solution Approach 2:
A detector detects the actual position of the sheet during conveyance, and this detection result is fed back to control the holding body's position adjustment. This closed-loop feedback system ensures accurate image positioning while maintaining a relatively simple conveyance structure.
2Manufacturing precision
If a detector and position corrector are added to correct sheet position, then image position accuracy is improved, but the device structure becomes more complex
Solution Approach 1:
The holding body serves multiple functions: it not only conveys the sheet forward but also performs position correction in the width direction and rotational correction. This multi-functionality reduces the need for separate correction mechanisms, thereby limiting the increase in device complexity.
Solution Approach 2:
The holding body acts as an intermediary between the conveyance system and the image transfer system. It absorbs the position and orientation variations of the sheet, protecting the image transfer process from these variations and simplifying the overall system design.
3Manufacturing precision
If the holding body rotates or shifts to correct sheet position, then image alignment is improved, but the control system becomes more complex
Solution Approach 1:
The detector continuously monitors the sheet position during conveyance, and this real-time feedback information is used to control the holding body's rotation and shifting movements. This feedback mechanism enables precise image alignment while keeping the control logic relatively simple and straightforward.
Solution Approach 2:
The system uses the detected sheet position information to automatically adjust the holding body's position without requiring external intervention or complex control algorithms. The system self-corrects based on the detection results, simplifying the control architecture.
Data Source
AI summary
An image forming apparatus includes an image forming device, a detector and a holding body. The image forming device is configured to perform an image formation to a sheet. The detector is configured to detect a position of a first image formed on a first surface of the sheet through the image formation of the image forming device. The holding body is configured to move while holding the sheet, by performing one of a rotation in a radial direction about a support shaft attached thereto in a direction perpendicular to an axial direction thereof and a lateral shift in a width direction of the sheet, operable to correct the position of the sheet based on a detection result obtained by the detector.