Fixing Shutter Geometry for Stable Sheet Conveyance
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Solution Overview
Problem
In image forming apparatuses with a fixing shutter, sheets can become jammed or improperly conveyed due to unstable behavior, especially when curled or hitting the shutter, leading to operational issues.
Innovation Solution
The apparatus includes a fixing guide and shutter conveying surface with specific inclinations and configurations to guide sheets smoothly, preventing jams and ensuring stable conveyance, while the fixing shutter is designed to open and close with the operation of attaching or detaching a cartridge, and a movable chute adjusts to prevent interference with other components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a fixing shutter is provided to prevent user contact with the heating member, then safety is improved, but sheet conveyance stability deteriorates due to sheets hitting the shutter or getting caught
Solution Approach 1:
The shutter conveying surface acts as an intermediary element between the fixing shutter and the sheet. It provides a guided transition path that mediates the interaction, preventing direct contact between the sheet and the shutter edge that causes jamming, while maintaining the shutter's safety function.
Solution Approach 2:
The inclination angle of the shutter conveying surface is specifically designed to be greater than the guide conveying surface. This parameter change creates an optimal transition geometry that accommodates sheet curvature and movement variations, preventing sheets from getting caught while maintaining stable conveyance.
2Object-affected harmful factors
If the fixing shutter is positioned to cover the heating unit, then safety is improved, but sheet conveyance path complexity increases
Solution Approach 1:
The shutter conveying surface and guide conveying surface are merged into a continuous, smoothly transitioning structure. This integration eliminates the need for separate adjustment mechanisms while maintaining both safety coverage and stable sheet flow through the combined surfaces.
Solution Approach 2:
The inclined surfaces of the shutter conveying surface and guide conveying surface create a curved transition path for the sheet. This curvature accommodates natural sheet behavior and ensures smooth flow around the shutter, reducing complexity compared to sharp-edged or multi-component designs.
3Ease of operation
If the shutter conveying surface is inclined to guide the sheet, then sheet guidance is improved, but the risk of sheet jamming increases if the inclination is too steep
Solution Approach 1:
The inclination angle of the shutter conveying surface is specifically designed to be greater than the guide conveying surface inclination angle. This optimized parameter creates the ideal balance between effective sheet guidance and preventing excessive speed or instability that could cause jamming.
Solution Approach 2:
Different inclination angles are applied to different surfaces: the shutter conveying surface has a greater inclination for active guidance, while the guide conveying surface has a smaller inclination for stable transition. This localized differentiation optimizes both guidance and stability without compromising either function.
Data Source
AI summary
An image forming apparatus includes: a fixing chute located upstream of a fixing device in a sheet conveying direction; a fixing guide opposing the fixing chute and including a guide conveying surface; and a fixing shutter opposing the fixing chute and configured to move between a closed position and an opened position. In a state in which the fixing shutter is positioned at the opened position, a shutter conveying surface of the fixing shutter is inclined in a direction approaching the fixing chute toward a downstream side in a sheet conveying direction such that an end portion of the shutter conveying surface on the downstream side is located closer to the fixing chute than an end portion of the guide conveying surface on an upstream side in the sheet conveying direction.