Fixing Device Torque Control for Image Disorder
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Solution Overview
Problem
Conventional fixing devices in image forming apparatuses experience image disorder when fixing images on paper with rough surfaces, due to uneven shear forces caused by differences in driving forces between the heating roller and pressing roller.
Innovation Solution
A fixing device with a control unit that adjusts the torques of the fixing motor and pressing motor to ensure the tangential force on the surface with the image is equal to or greater than the tangential force on the back surface, and adjusts this relationship based on the paper's smoothness, using sensors to detect smoothness and torque levels for feedback control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the heating roller and pressing roller rotate independently with conventional speed control, then the fixing process can be simplified, but image disorder occurs on rough surface paper due to uneven shear forces
Solution Approach 1:
The patent changes the control parameter from simple speed control to torque control of the motors driving the heating roller and pressing roller. By controlling the torques T1 and T2, the system ensures that tangential force F1 on the image surface is equal to or greater than tangential force F2 on the back surface, preventing image disorder while maintaining independent rotation capability
Solution Approach 2:
The patent introduces feedback control mechanisms including torque detection units to monitor T1 and T2, and smoothness detection units to detect paper surface characteristics. The control unit adjusts motor torques based on this feedback to maintain optimal tangential force distribution, resolving the contradiction between simple control and high-quality image fixation
2Ease of operation
If the tangential force on the back surface of paper is greater than on the image surface, then paper conveyance is facilitated, but shear force removes toner and causes image disorder
Solution Approach 1:
The patent applies asymmetric force distribution by ensuring F1 (tangential force on image surface) ≥ F2 (tangential force on back surface). This asymmetric control prevents the harmful scenario where F2 > F1, thereby preventing toner removal while still enabling adequate paper conveyance through the controlled shear force
Solution Approach 2:
By changing from speed control to torque control, the system can precisely adjust the magnitude relationship between F1 and F2. The control unit regulates motor torques to maintain F1 ≥ F2, optimizing both paper conveyance and image protection simultaneously
3Device complexity
If a fixed torque relationship between fixing motor and pressing motor is used, then control is simplified, but image disorder occurs on paper with varying smoothness
Solution Approach 1:
The patent implements dynamic torque control where the relationship between T1 and T2 varies based on detected paper smoothness. The control unit adjusts motor torques in real-time according to paper characteristics, transforming the static fixed-torque system into a dynamic adaptive system that maintains optimal performance across different paper types
Solution Approach 2:
Smoothness detection units provide feedback about paper surface characteristics, enabling the control unit to adjust torque relationships adaptively. This feedback mechanism allows the system to optimize image fixation quality for each paper type while maintaining manageable control complexity through automated adjustment
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 reduces image disorder on paper surfaces of varying smoothness by applying a suitable shear force, ensuring proper image fixation regardless of the paper's surface roughness.
Implementation Method 1
a fixing device for fixing an image formed with toner or the like on paper... a heating roller and a pressing roller rotating independently of each other
Implementation Method 2
belt 901 moves relative to paper 900 to exert force (shear force) on region B in the moving direction of belt 901. This removes toner TX from paper 900
Data Source
AI summary
A control unit is configured to control torque of a fixing motor and torque of a pressing motor such that tangential force at a part holding paper in cooperation with a fixing member in a pressing member is equal to or greater than tangential force at a part holding paper in cooperation with the pressing member in the fixing member, and that the relation between the tangential force at the part of the pressing member and the tangential force at the part of the fixing member changes in accordance with the smoothness of paper.