Eccentric Cam Pressurization Control for Image Fixing
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Solution Overview
Problem
Existing image forming apparatuses face challenges in accurately controlling the pressurizing force of the nip portion, leading to instability and inefficiency in switching between different operational modes, particularly when transitioning from pressurization releasing mode to pressurizing mode or from standby mode to pressurizing mode.
Innovation Solution
The apparatus employs a cam mechanism driven by a motor, with controlled rotational speeds and angles to manage the pressurizing force, using a control unit to adjust the motor's speed based on rotational positions, ensuring precise control of the pressurizing force during mode shifts, thereby stabilizing the rotational stop positions and maintaining productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the motor rotates the cam at a high rotational speed to improve productivity, then the image forming efficiency is improved, but the cam member overruns when braked to stop, causing instability in stopping position
Solution Approach 1:
The patent applies dynamics by making the rotational speed of the motor variable rather than constant. The control unit adjusts the rotational speed based on the operational mode: using a first rotational speed for mode switching operations and a second rotational speed for image forming operations. This dynamic speed adjustment allows the system to achieve both stable stopping during mode transitions and high productivity during image forming.
Solution Approach 2:
The patent changes the parameter of rotational speed from a fixed value to a variable parameter that adapts to different operational requirements. By switching between two distinct rotational speeds (first rotational speed for stability during mode switching, second rotational speed for productivity during image forming), the system resolves the contradiction between reliable stopping and high productivity.
2Speed
If the cam member is braked to stop quickly to improve response time for mode switching, then the switching speed is improved, but the rotor rotates at speed equal to or higher than the rotating magnetic field, causing overrun
Solution Approach 1:
The patent applies preliminary action by controlling the motor to rotate at a first rotational speed specifically during mode switching operations before transitioning to the second rotational speed for image forming. This preliminary speed control ensures that the cam member stops accurately at predetermined positions during mode switching, preventing overrun while maintaining adequate switching speed.
Solution Approach 2:
The control unit implements feedback control by monitoring the rotational position of the cam member and adjusting the motor speed accordingly. During mode switching, the system uses the first rotational speed that accounts for the braking characteristics and prevents overrun, ensuring the cam member stops at the correct position without excessive speed.
3Reliability
If the pressurizing force is increased to improve image fixation quality, then the fixing reliability is improved, but the cam member receives acceleration in speed increasing direction, causing rotor to overrun
Solution Approach 1:
The patent applies dynamics by adjusting the rotational speed of the motor according to the pressurizing force requirements. When high pressurizing force is needed for image fixation, the system uses the first rotational speed that prevents overrun while still achieving the necessary cam rotation for proper pressurization. This dynamic speed control allows the system to maintain both fixation quality and positional precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables stable and accurate control of the pressurizing force, reducing the risk of overrunning and ensuring precise stopping at predetermined angles, thereby enhancing the reliability and efficiency of the image forming process.
Implementation Method 1
a rotor rotates at a speed equal to or higher than a rotational speed of a rotating magnetic field of a stator
Data Source
AI summary
A fixing device causes an eccentric cam to perform a rotation step of 113° to shift from a pressurization releasing mode to a pressurization mode, and causes the eccentric cam to perform a rotation step of 263° to shift from a standby mode to the pressurization mode. A control unit activates a motor by setting a rotational speed of a rotational magnetic field of a stator to 600 rpm in the rotation step of 113° and to 1500 rpm in the rotation step of 263° so as to prevent the eccentric cam from receiving acceleration of a rotational direction from a pressure lever before a rotational speed of a rotor reaches a first rotational speed. Then, the control unit stops the rotational magnetic field of the stator based on an output of a photo interrupter.