Discharge Roller Tilt for Image Trace Suppression
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Solution Overview
Problem
In image forming apparatuses, the increased processing speed and reduced size lead to toner sticking issues on discharge rollers, causing image quality degradation due to roller traces, which conventional solutions like tilting discharge rollers or increasing toner resistance cannot fully prevent without increasing component count and size.
Innovation Solution
The design incorporates a driving rotation member and a driven rotation member with a tilting rotation shaft and an urging member, allowing for adjustable nip pressure by changing the tilt angle and diameter, enabling effective toner removal and image formation on both sides of the sheet without increasing the apparatus size or component count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the processing speed is increased and the size is reduced, then productivity is improved, but the distance between fixing unit and discharge roller decreases causing toner to stick to discharge roller surface
Solution Approach 1:
The patent changes the physical parameters of the discharge roller by tilting the rotation shaft at a specific angle (5-15 degrees) relative to the sheet conveyance direction. This parameter change allows the roller to effectively remove toner while maintaining high processing speed and compact size
2Manufacturing precision
If discharge rollers are tilted to prevent roller trace, then image quality is improved, but end portion of discharge roller contacts sheet producing linear trace
Solution Approach 1:
The patent applies local quality by creating different nip pressures at different locations of the discharge roller. The tilted configuration ensures that the main contact area has optimal pressure for toner removal, while the end portions have reduced contact pressure to avoid producing linear traces on the sheet
3Manufacturing precision
If nip pressure of discharge roller pair is decreased to improve linear trace, then image quality is improved, but re-conveyance path and shutter mechanism are subjected to resistance
Solution Approach 1:
The patent introduces asymmetry by tilting the driven rotation shaft at a specific angle relative to the driving rotation shaft. This asymmetric configuration creates an optimal balance where sufficient nip pressure is maintained for effective toner removal and sheet conveyance, while the end portions contact the sheet at reduced pressure to minimize linear traces
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively suppresses roller traces during sheet discharge while maintaining high image quality by adjusting nip pressure based on rotation direction, allowing for a compact and cost-effective image forming apparatus.
Implementation Method 1
a driven rotation member arranged opposing the driving rotation member, and configured to be driven to rotate by the driving rotation member
Data Source
AI summary
The present invention is directed to downsize the main body and achieve a good image quality at a low cost. A rotation shaft of a first discharge roller is tilted with respect to that of a second discharge roller. The center of oscillation C of a first discharge roller holding member is provided more upstream in the direction in which a sheet is discharged than a straight line made by the rotation center of the first discharge roller and the rotation center of the second discharge roller.