Sheet Conveying Roller Speed Control for Image Transfer
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Solution Overview
Problem
Existing sheet conveying devices in image forming apparatuses face challenges in accurately controlling the deflection and timing of sheet conveyance, leading to variations in deflection amount due to delays or positional deviations, which can affect the precision of image transfer.
Innovation Solution
A sheet conveying device with a conveying roller pair, resist roller pair, sheet sensor, resist control unit, and conveying speed control unit that adjusts the rotational speed of the rollers based on elapsed time from writing timing to leading edge detection, ensuring precise deflection and feed timing for consistent image transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the conveying roller is stopped and then re-driven to synchronize with the resist roller pair, then the sheet feed timing can be synchronized with transfer start timing, but time loss occurs during the re-driving process
Solution Approach 1:
The conveying roller is decelerated in advance before the sheet reaches the resist roller pair, rather than stopping and re-driving. This preliminary speed adjustment allows the sheet to be fed at the correct timing without the time loss associated with stopping and restarting the conveying roller
Solution Approach 2:
The conveying roller transitions from a static stop-start operation to a dynamic continuous rotation with variable speed. By continuously adjusting the rotational speed of the conveying roller, the system achieves precise timing synchronization while maintaining continuous motion, eliminating the time loss from repeated stopping and starting
2Loss of time
If the conveying roller is continuously driven without stopping, then time loss during re-driving is eliminated, but precise control of sheet deflection and feed timing becomes more difficult
Solution Approach 1:
A sheet sensor detects the leading edge of the sheet and provides feedback to the control unit. The control unit uses this feedback information to adjust the conveying roller speed dynamically, ensuring precise timing control while maintaining continuous rotation. This closed-loop control system manages the complexity by using real-time sensor data to automatically adjust roller speed
Solution Approach 2:
The system changes the operational parameter of the conveying roller from constant speed to variable speed. By dynamically adjusting the rotational speed parameter based on sheet position feedback, the system achieves precise timing control without stopping the roller, balancing continuous operation with timing precision
3Manufacturing precision
If the resist roller pair is used to deflect the sheet, then sheet inclination can be corrected, but variations in leading edge detection timing cause variations in deflection amount
Solution Approach 1:
The conveying roller speed is adjusted in advance based on the detected leading edge position and the calculated elapsed time from writing timing. This preliminary speed adjustment ensures that the sheet arrives at the resist roller pair at the correct timing, allowing consistent deflection amount regardless of variations in leading edge detection timing
Solution Approach 2:
The system dynamically changes the conveying roller speed parameter to compensate for timing variations. By calculating the elapsed time from writing timing to leading edge detection and adjusting the roller speed accordingly, the system maintains consistent sheet deflection amount even when leading edge detection timing varies
Data Source
AI summary
A sheet conveying device includes: a conveying roller pair; a resist roller pair; a sheet sensor; a resist control unit that controls rotational driving of the resist roller pair, and a conveying speed control unit. 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 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.