Registration Roller Swing for Sheet Deviation Correction
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Solution Overview
Problem
In image forming apparatuses, the detection of the leading end of a sheet before the registration roller pair can result in varying positions and timing due to sheet deviation and acceleration instability, leading to inconsistent toner image placement.
Innovation Solution
The apparatus includes a deviation detecting portion to correct sheet deviation and a leading end detecting portion positioned downstream, ensuring stable detection after deviation correction, thereby maintaining consistent toner image placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the leading end detection sensor detects the leading end of the sheet before the registration roller pair swings, then the detection timing is early, but the detected position varies due to sheet deviation and acceleration instability
Solution Approach 1:
The registration roller pair performs preliminary swing action to correct sheet deviation before the leading end detection sensor detects the sheet. The sheet deviation correction is completed in advance, ensuring that when detection occurs, the sheet is already positioned correctly, eliminating position variation in the detected leading end.
Solution Approach 2:
The registration roller pair acts as an intermediary between the sheet feeding mechanism and the leading end detection sensor. It corrects sheet deviation and stabilizes sheet position before the sheet reaches the detection sensor, ensuring accurate and consistent detection results.
2Manufacturing precision
If the registration roller pair swings to correct sheet deviation, then sheet positioning accuracy improves, but the swing amount varies during acceleration period
Solution Approach 1:
The system uses feedback control where the sheet deviation detection sensor detects the actual sheet position, and this information is fed back to control the registration roller pair's swing amount. The swing amount is adjusted based on actual sheet deviation, ensuring accurate positioning while compensating for acceleration variations.
Solution Approach 2:
The registration roller pair's swing speed is made variable rather than constant. The swing speed is adjusted according to the detected sheet deviation amount and timing, allowing the system to adapt to different sheet conditions and maintain positioning accuracy despite acceleration variations.
3Loss of time
If the leading end detection sensor is positioned upstream, then detection occurs earlier, but sheet skew cannot be corrected at the nip portion
Solution Approach 1:
The registration roller pair performs preliminary skew correction by swinging to align the sheet's side end with the reference position before the leading end reaches the detection sensor. This preliminary action ensures that both deviation and skew are corrected in advance, enabling reliable detection and subsequent consistent toner image placement.
Data Source
AI summary
An image forming apparatus reflecting one aspect of the present invention includes a deviation detecting portion, a registration roller, and a leading end detecting portion. The deviation detecting portion detects a deviation amount of the sheet being fed from a reference position in a sheet width direction orthogonal to a feeding direction. The registration roller modifies deviation by swinging the sheet being fed in the sheet width direction in accordance with the deviation amount detected by the deviation detecting portion. The leading end detecting portion is disposed on the downstream side in the sheet feeding direction of the registration roller and detects a leading end of the sheet being fed. The leading end detecting portion detects the leading end of the sheet after deviation is modified by the registration roller.