Registration Roller Skew Correction via Loop Formation
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Solution Overview
Problem
Conventional skew correction devices in image forming apparatuses face challenges in maintaining high productivity and accurate skew correction due to limitations in setting the registration roller pair to a separated and press-contact state, especially with faster sheet conveyance speeds and shorter intervals between sheets, leading to potential nipping of the leading edge and deteriorated skew correction performance.
Innovation Solution
A sheet conveyance apparatus with a control unit that sets the registration roller pair to a separated state after a preceding sheet reaches the transfer unit, then sets it to a press-contact state after a succeeding sheet stops near the nip portion, allowing for backward rotation to form a loop and ensure accurate alignment, thereby improving skew correction and productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the sheet conveyance speed is increased to improve productivity, then productivity is improved, but the interval between sheets becomes shorter causing the registration roller pair to be set to press-contact state after the succeeding sheet has reached the stop position, leading to potential nipping of the leading edge and deteriorated skew correction performance
Solution Approach 1:
The control unit sets the registration roller pair to the separated state in advance before the succeeding sheet reaches the stop position. This preliminary action ensures that when the sheet conveyance speed is increased, the registration roller pair is already in the separated state, preventing nipping of the leading edge while maintaining high productivity
Solution Approach 2:
The registration roller pair dynamically switches between separated state and press-contact state based on the timing of sheet conveyance. The control unit monitors the sheet interval and adjusts the roller pair state accordingly, enabling the system to adapt to varying conveyance speeds and maintain reliable skew correction
2Manufacturing precision
If the registration roller pair is set to separated state after the preceding sheet reaches the transfer unit, then image transfer accuracy is improved, but the press-contact operation cannot be completed before the succeeding sheet contacts the nip portion, causing leading edge nipping
Solution Approach 1:
The control unit uses feedback from sheet detection to determine the optimal timing for switching the registration roller pair between separated and press-contact states. By monitoring when the succeeding sheet reaches the stop position, the control unit adjusts the roller pair state timing to prevent nipping while maintaining image transfer accuracy
Solution Approach 2:
The system automatically coordinates the roller pair state changes with sheet conveyance timing without requiring external intervention. The control unit manages the entire sequence of separating the roller pair after image transfer and pressing it before the next sheet arrives, enabling seamless operation
Data Source
AI summary
A sheet conveyance apparatus includes a conveyance roller pair, a conveyance roller driving unit, a registration roller pair, a registration driving unit, a separation and press-contact unit configured to set the registration roller pair to a separated state and to a press-contact state, and a control unit. After a sheet has stopped at a stop position immediately before the registration roller pair, the registration roller pair having been set to the separated state is set to the press-contact state. The registration roller pair is rotated backward during formation of a loop in the sheet.