Image Forming Apparatus Sheet Curl Control
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Solution Overview
Problem
Existing image forming apparatuses face issues with electric discharge noise and image displacement due to the varying position of the sheet in relation to the image carrier, particularly when the sheet is curled, as existing solutions only address the posture of the sheet's front end and not the entire sheet.
Innovation Solution
The image forming apparatus includes a controller that adjusts the position defining angle of a sheet passing guide member and a belt contact roller to control the contact start position between the sheet and the intermediate transfer belt, ensuring the distance from the secondary transfer nip remains within a suitable range to prevent noise and displacement, using detectors to measure the curled amount and apply appropriate control measures based on sheet type and configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the sheet and intermediate transfer belt contact start position is adjusted closer to the transfer nip, then electric discharge noise is reduced, but image displacement occurs due to speed difference
Solution Approach 1:
The patent applies dynamics by making the sheet passing guide member adjustable in position. The guide member can be dynamically repositioned along the sheet conveying path to adapt to different sheet curling states. This dynamic adjustment allows the system to optimize the contact start position between sheet and intermediate transfer belt, preventing both electric discharge noise (by avoiding contact too close to transfer nip) and image displacement (by ensuring proper contact timing), thus resolving the technical contradiction between these two harmful effects.
2Device complexity
If the sheet passing guide member position is fixed, then device complexity is reduced, but cannot suppress problems throughout the entire sheet when curled
Solution Approach 1:
The patent implements dynamics by transforming the fixed sheet passing guide member into an adjustable one. The guide member can be positioned at different locations along the sheet conveying path based on detected sheet curling amounts. This dynamic positioning capability enables the system to maintain reliable image forming quality across various sheet conditions without significantly increasing device complexity, as the adjustment mechanism is integrated into the existing guide structure.
3Object-affected harmful factors
If the contact start position is too far from the transfer nip, then electric discharge noise is avoided, but image displacement occurs due to speed difference between intermediate transfer belt and sheet
Solution Approach 1:
The patent applies feedback by incorporating a sheet curling amount detector that continuously monitors the sheet state and provides information to the controller. The controller uses this feedback to automatically adjust the sheet passing guide member position, thereby optimizing the contact start position between sheet and intermediate transfer belt. This closed-loop feedback system ensures that the contact position is dynamically optimized to prevent both electric discharge noise and image displacement, resolving the contradiction between these two harmful effects.
Data Source
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AI summary
An image forming apparatus includes the following. An image carrier carries a toner image. A transfer unit transfers a toner image held by the image carrier onto a sheet. A controller controls a relation of a position between the image carrier and the sheet so that the sheet continues to come into contact with the image carrier from a position where a distance from a transfer nip is within a predetermined range when the sheet enters the transfer nip during an image forming job. The transfer nip is formed by the image carrier and the transfer unit.