Sheet Processing Skew Correction and Punching Control
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Solution Overview
Problem
High-speed image forming apparatuses face challenges in accurately stopping sheets at regular positions for punching processing due to high conveying speeds, leading to potential deviations in punch hole positions and increased time for skew correction, while also requiring power-saving measures.
Innovation Solution
A sheet processing apparatus with a skew detecting unit that measures skew at both sheet edges, an attitude control unit for correcting skew by adjusting the hole punching section, and a control unit that decelerates the conveying motor to stop the sheet accurately for precise punching, reducing skew detection errors and ensuring accurate punch hole placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the image forming apparatus operates at higher speed, then productivity is improved, but the sheet conveying speed becomes higher causing difficulty in stopping the sheet at a regular position and deviation in punch hole position
Solution Approach 1:
The system performs preliminary skew detection at the forward edge of the sheet before the sheet reaches the punching position. The detected skew amount is used to pre-adjust the punching unit's position, so that when the sheet arrives at the punching position, the punch hole is already correctly positioned despite the sheet's skew. This preliminary action allows high-speed processing while maintaining punching accuracy.
Solution Approach 2:
The system uses skew detection sensors to continuously monitor the sheet's skew condition and provides feedback to the control unit. The control unit adjusts the punching unit's position based on this feedback, ensuring accurate punch hole placement even at high conveying speeds. The feedback loop enables real-time compensation for sheet skew without reducing processing speed.
2Manufacturing precision
If skew correction is performed more accurately, then manufacturing precision is improved, but the time required for skew correction increases
Solution Approach 1:
The system performs skew detection at the forward edge of the sheet before the sheet fully enters the punching unit. The skew amount is calculated and the punching unit position is adjusted in advance, so that skew correction and punching can occur simultaneously or in overlapping time periods. This eliminates the need for separate skew correction time and maintains high processing speed.
Solution Approach 2:
The system merges the skew correction function with the punching operation. The skew detection, calculation, and punching unit position adjustment are integrated into the sheet conveying and punching process, allowing skew correction to occur during the sheet's movement rather than as a separate step. This combining of functions reduces total processing time while maintaining correction accuracy.
3Manufacturing precision
If the sheet conveying speed is reduced to stop the sheet accurately, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
The system performs preliminary skew detection and punching unit position adjustment while the sheet is still moving at high speed. The sheet does not need to be completely stopped for skew correction or position adjustment, as these actions are already completed by the time the sheet reaches the punching position. This allows accurate punching without reducing the overall conveying speed.
Solution Approach 2:
The system makes the punching unit dynamically adjustable during sheet conveyance. The punching unit's position can be changed in real-time based on skew detection, allowing the system to adapt to sheet skew without stopping the conveying process. This dynamic adjustment maintains both high productivity and punching accuracy.
Data Source
AI summary
A sheet processing apparatus includes a conveying motor for conveying a sheet along a conveying path, a skew detecting unit configured to detect a quantity of skew of the conveyed sheet, a hole punching section arranged downstream from the skew detecting unit, an attitude control unit configured to carry out skew correction by changing tilt angle of the hole punching section in accordance with the quantity of skew, a detecting unit configured to detect the forward edge and the rear edge of the sheet conveyed into the hole punching section, and a control unit configured to control the conveying motor to control the conveying speed of the sheet. During a period from when the detecting unit detects the forward edge of the sheet until the detecting unit detects the rear edge, the sheet is decelerated from a first conveying speed to a second conveying speed. After the detecting unit detects the rear edge of the sheet, the conveying of the sheet is stopped and punching processing to the sheet is executed when the conveying is stopped.