Motor Speed Control for Sheet Interval Stability
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Solution Overview
Problem
In image forming apparatuses, maintaining a consistent sheet interval is challenging due to variations in sheet conveyance speed and load torque, which affects productivity and accuracy, especially when using low-output motors.
Innovation Solution
Incorporating a torque detection unit and control unit to dynamically adjust the rotational speed of the motor based on detected load torque, ensuring the sheet interval approaches a target value by modifying the target interval in speed control during conveyance operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high-output motor is selected to perform acceleration with margin under large load torque conditions, then the sheet interval can be maintained at target value, but the productivity is reduced when using low-output motors
Solution Approach 1:
The patent applies dynamics by making the target interval variable rather than fixed. The control unit dynamically adjusts the target interval based on detected load torque conditions, allowing the system to adapt between different motor output scenarios. This resolves the contradiction by enabling low-output motors to achieve acceptable sheet interval control through adaptive target adjustment.
Solution Approach 2:
The patent changes the parameter of target interval based on load torque detection. When load torque exceeds thresholds, the target interval is modified to account for acceleration limitations. This parameter change allows the system to maintain reliable sheet interval control with low-output motors under high load conditions without sacrificing productivity.
2Manufacturing precision
If the target speed is set to a high value to adjust sheet interval to target value, then the sheet interval can be maintained, but the load torque applied to motor increases
Solution Approach 1:
The patent implements feedback by detecting load torque and using this information to adjust the target interval. The control unit continuously monitors load torque conditions and modifies the target interval accordingly, creating a closed-loop system that balances sheet interval accuracy with motor load constraints.
Solution Approach 2:
The target interval is made dynamic rather than static, adjusting based on real-time load torque conditions. This allows the system to achieve accurate sheet interval control when conditions permit while accommodating higher load torque situations by adjusting expectations.
3Ease of manufacture
If a low-output motor is used to convey sheets, then cost is reduced, but the sheet interval control becomes unstable under varying load conditions
Solution Approach 1:
The patent changes the target interval parameter based on load torque detection, allowing low-output motors to operate reliably across varying load conditions. By adapting the target interval to match actual motor capabilities under different loads, the system maintains sheet interval control stability without requiring expensive high-output motors.
Data Source
AI summary
An image forming apparatus includes a conveyance unit to convey a sheet toward an image forming position, a torque detection unit to detect a load torque applied to a motor driving the conveyance unit, and a control unit to perform a speed control for changing a rotational speed of the motor such that an interval at which a preceding sheet and a succeeding sheet pass through the image forming position approaches a target interval while the conveyance unit is conveying the succeeding sheet. The control unit executes an interval change processing for changing the target interval in the speed control based on a magnitude of a detected load torque when the conveyance unit is driven by the motor, the control unit controls power input to the motor by transmitting a command signal to a driving circuit of the motor, and the torque detection unit detects the command signal.