Sheet Conveying Roller Speed Control for Consistent Skew Correction
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Solution Overview
Problem
Existing sheet conveying devices in image forming apparatuses face challenges in accurately correcting sheet inclination and ensuring consistent deflection amounts due to variations in leading edge detection timing, leading to inefficiencies in image transfer processes.
Innovation Solution
A sheet conveying device with a conveying roller pair, resist roller pair, and control units that adjust rotational speeds and timings to maintain a predetermined deflection amount by controlling the resist roller pair to stop and then feed the sheet at specific timings, and adjusting the conveying roller speed based on elapsed times from writing start to leading edge detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the conveying roller is stopped and then re-driven to perform the resist operation, then the sheet inclination can be corrected by forming deflection, but time loss occurs during the stop and re-drive process
Solution Approach 1:
The conveying roller is decelerated in advance before the resist operation timing, and then continuously driven without stopping. This preliminary speed adjustment allows the sheet to be fed at the correct timing while eliminating the time loss associated with stopping and re-driving the conveying roller.
Solution Approach 2:
The conveying roller transitions from continuous rotation to decelerated rotation, and then to synchronized rotation with the resist roller pair. This dynamic speed adjustment enables the system to maintain continuous operation while achieving precise sheet positioning and feed timing.
2Loss of time
If the conveying roller is continuously driven without stopping, then time loss is eliminated, but it becomes difficult to control the sheet feed timing to match transfer start timing
Solution Approach 1:
The control unit monitors the rotational speeds of both the conveying roller and resist roller pair, and adjusts the conveying roller speed based on the timing relationship between sheet feed and image transfer start. This feedback control ensures precise synchronization while maintaining continuous roller operation.
Solution Approach 2:
The rotational speed of the conveying roller is dynamically changed from initial rotation to decelerated rotation, and then to synchronized rotation matching the resist roller pair. This parameter adjustment enables precise timing control without stopping the roller.
3Adaptability or versatility
If the leading edge detection timing varies, then adaptability to different sheet conditions is improved, but variations in deflection amounts occur
Solution Approach 1:
The conveying roller is decelerated in advance based on the detected leading edge timing, creating a buffer that compensates for timing variations. This preliminary speed adjustment ensures that regardless of when the leading edge is detected, the sheet will be positioned correctly for the resist operation.
Solution Approach 2:
The system dynamically adjusts the conveying roller speed based on the actual leading edge detection timing. By varying the deceleration timing and amount according to detected conditions, the system maintains consistent deflection amounts despite variations in sheet arrival times.
Data Source
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AI summary
A sheet conveying device (10) includes: a conveying roller pair (23A, 23B); a resist roller pair (80); a sheet sensor (61); a resist control unit (95) that controls rotational driving of the resist roller pair, and a conveying speed control unit (96). The conveying speed control unit controls, on the basis of an elapsed time from predetermined writing timing at which light scanning on a photoreceptor drum included in an image forming unit (14) starts to leading edge detection timing at which the sheet sensor detects a leading edge of a sheet, a rotational speed of the conveying roller pair such that a feeding amount of the sheet after the leading edge detection timing is a predetermined reference conveying amount.