Transfer Nip Control via Motor Feedback in Image Forming Apparatus
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Solution Overview
Problem
Existing image forming apparatuses face instability in transfer nip amount due to motor torque variations and sheet thickness variations, leading to image disturbances and fluctuations in transfer nip, which are not adequately addressed by conventional cam abutment methods.
Innovation Solution
The image forming apparatus employs a detector to monitor the rotation angle of the motor and a hardware processor to execute first control with constant torque and second control at predetermined timing, adjusting the transfer nip amount by controlling the cam-driven secondary transfer roller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cam abutment method is used to adjust pressing force, then transfer nip formation is enabled, but motor torque variations and sheet thickness variations cause instability in transfer nip amount
Solution Approach 1:
The patent applies feedback control by detecting the cam's rotational angle with a detector and using this information to control the motor's operation. The controller adjusts the motor's torque and rotation based on the detected angle, creating a closed-loop system that compensates for motor torque variations and sheet thickness variations, thereby stabilizing the transfer nip amount.
Solution Approach 2:
The patent changes the motor's operating parameters (torque and rotation speed) based on the detected cam angle. By dynamically adjusting these parameters during the cam's rotation, the system maintains stable transfer nip formation despite variations in motor torque and sheet thickness, resolving the contradiction between reliability and the need for complex control.
2Ease of operation
If motor operates at fixed current for cam abutment, then simple control is achieved, but transfer nip amount fluctuates due to torque variations
Solution Approach 1:
The patent transitions from static (fixed current) control to dynamic control by adjusting the motor's torque and rotation speed based on the cam's real-time rotational angle. This dynamic adjustment ensures consistent transfer nip formation while maintaining reasonable control complexity through automated feedback-based parameter modulation.
3Productivity
If cam abutment timing is determined by fixed time, then control is simplified, but transfer nip instability occurs due to sheet thickness variations
Solution Approach 1:
The patent replaces time-based mechanical timing with angle-based detection control. By using a detector to monitor the cam's rotational angle and controlling the motor based on this angular position, the system achieves both rapid response and stable transfer nip formation regardless of sheet thickness variations, eliminating the need for complex time-based synchronization.
Data Source
AI summary
An image forming apparatus that has a transfer device that includes an intermediate transfer belt that is tensioned by a plurality of support rollers, a secondary transfer roller that faces one of the support rollers via the intermediate transfer belt, a cam that adjust a pressing force that presses the intermediate transfer belt by the secondary transfer roller, a motor that drives the cam, and a conveyor that conveys a recording medium to a transfer nip formed between the intermediate transfer belt and the secondary transfer roller is provided with a controller that controls an operation of the motor. The controller executes first control of operating the motor with a constant torque and stopping the motor when a rotation angular speed of the motor is less than or equal to a first threshold and second control of operating the motor at a predetermined timing to adjust a transfer nip amount.