Nip Angle Adjusting Section for Scratch Prevention in Image Forming Apparatus
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Solution Overview
Problem
Conventional electrophotographic image forming apparatuses face challenges in preventing scratches on printed sheets due to curl formation and contact with guide members, especially during high-speed production, and existing solutions either require additional space for conveyance rollers or exacerbate jamming and corner folding issues.
Innovation Solution
An image forming apparatus with a nip angle adjusting mechanism that changes the angle of the conveyance rollers based on whether the sheet is being conveyed with an image on its first or second surface, allowing for optimal sheet alignment to avoid guide member contact and reduce scratches without the need for additional conveyance rollers in the sheet feeding path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conveyance roller is disposed in the sheet feeding path to prevent scratch, then scratch prevention is improved, but device complexity and space requirements increase
Solution Approach 1:
The patent changes the nip angle parameter of the conveyance roller section to prevent scratch. By adjusting the nip angle to be within a specific range (0° to 30°), the sheet is conveyed at an optimized angle that prevents contact with guide members, thereby preventing scratch without adding additional conveyance rollers
Solution Approach 2:
The conveyance roller section performs multiple functions: it conveys the sheet from the fixing section and simultaneously controls the sheet angle through nip angle adjustment to prevent scratch. This eliminates the need for separate scratch-prevention mechanisms
2Object-affected harmful factors
If the nip angle of conveyance roller section is increased to prevent scratch, then scratch prevention is improved, but sheet alignment and conveyance stability deteriorate
Solution Approach 1:
The patent identifies an optimal parameter range for the nip angle (0° to 30°) that balances scratch prevention with sheet alignment. Within this range, the sheet is conveyed at an angle sufficient to prevent guide member contact while maintaining proper alignment and conveyance stability
3Device complexity
If conventional conveyance roller configuration is used, then device simplicity is maintained, but scratch occurs due to sheet contact with guide members
Solution Approach 1:
The patent modifies the nip angle parameter of the existing conveyance roller configuration to prevent scratch. By adjusting the nip angle within the optimal range, the sheet conveyance path is optimized to prevent contact with guide members, eliminating scratch while maintaining device simplicity
Data Source
AI summary
An image forming apparatus includes: a toner image forming section; a transfer section; a fixing section; a conveyance roller section disposed on a downstream side of the fixing section in a sheet conveyance direction; a conveyance guide section disposed on a downstream side of the conveyance roller section and including a first guide member disposed on a fixing side of a sheet and a second guide member disposed on a rear surface side of the sheet; a feeding-path-switching section disposed on a downstream side of the conveyance guide section and configured to switch sheet feeding paths; and a nip angle adjusting section configured to change a nip angle of a conveyance nip in accordance with whether a sheet on which an image is formed on a first surface thereof is conveyed, or a sheet on which an image is formed on a second surface thereof is conveyed.