Fixing Belt Stress Distribution via Variable Cross-Section Pusher
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Solution Overview
Problem
The existing fixing devices using the slide belt method face issues with stress concentration and early belt deformation, particularly when fixing toner images onto paper sheets of varying sizes, leading to non-uniform temperature distribution and reduced device lifespan.
Innovation Solution
A fixing device with a rotatable fixing belt, a pressurizing member, a heat source, and a temperature sensing device that detects temperature at the inner circumferential surface of the fixing belt near the end portion of the fixing nip, allowing for controlled heating and stress distribution to prevent local deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the slide belt method is employed to reduce heat capacity and improve heating efficiency, then the warm-up period is reduced and energy saving is achieved, but stress is concentrated on the fixing belt in the neighboring region of the end portion of the fixing nip, causing local deformation and early belt breaking
Solution Approach 1:
The pushing member is designed with a variable cross-sectional shape where the central portion has different dimensions than the end portions. Specifically, the width and/or thickness of the central portion is reduced compared to the end portions, which distributes the stress more evenly across the fixing belt and prevents stress concentration at the end portions of the fixing nip, thereby preventing local deformation and extending belt lifespan while maintaining the heating efficiency of the slide belt method
2Strength
If the fixing belt is formed of a relatively hard material to improve durability, then strength is increased, but stress concentration becomes more intense, leading to earlier belt breaking
Solution Approach 1:
By designing the pushing member with a variable cross-sectional shape (narrower central portion compared to end portions), the stress distribution on the fixing belt is optimized. This allows the use of harder, more durable belt materials without experiencing premature failure due to stress concentration, as the modified pushing member geometry prevents intense stress buildup at critical locations
3Temperature
If a thermally conductive member is added to prevent excessive temperature rise in non-first size sheet passage regions, then temperature distribution uniformity is improved, but device complexity increases
Solution Approach 1:
The temperature sensing device is integrated into the existing pushing member structure, allowing it to serve dual purposes: monitoring temperature in the first size sheet passage region and indirectly controlling temperature distribution across the entire fixing belt. This eliminates the need for separate thermally conductive members in non-first size regions, maintaining temperature uniformity while avoiding increased device complexity
Solution Approach 2:
The temperature sensing device provides real-time temperature feedback from the first size sheet passage region, enabling the control unit to adjust heating operations to prevent excessive temperature rise in non-first size sheet passage regions. This feedback-based control achieves temperature distribution uniformity without adding complex thermal management structures
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 configuration ensures uniform heat distribution across different paper sizes, prevents excessive temperature rise in non-standard sheet passage regions, and extends the lifespan of the fixing device by reducing stress concentration and maintaining efficient heating.
Implementation Method 1
The heat source heats the fixing belt
Implementation Method 2
The temperature sensing device has a sensing element that is in contact with an inner circumferential surface of the fixing belt
Data Source
AI summary
A fixing device includes a fixing belt, a pressurizing member, a heat source, and a temperature sensing device. The fixing belt is rotatably provided. The pressurizing member is rotatably provided and is in pressed contact with the fixing belt to form a fixing nip between the pressurizing member and the fixing belt. The heat source heats the fixing belt. The temperature sensing device detects the temperature of the fixing belt. The temperature sensing device has a sensing element that is in contact with an inner circumferential surface of the fixing belt in a neighboring region of an end portion of the fixing nip and a pressing member configured to press the sensing element against the inner circumferential surface of the fixing belt.