Fixing Device Heat Equalizing Member Nip Width Control
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Solution Overview
Problem
Conventional fixing devices in image forming apparatuses face challenges in effectively fixing toner images onto recording media due to issues with heat equalization and pressure distribution, leading to non-uniform temperature and potential jamming.
Innovation Solution
A fixing device with a rotatable endless fixing member, a heat source, and a pressure member forming a nip, where the nip forming portion includes a base material and a heat equalizing member with a bent portion that hooks over a convex part of the base material, ensuring proper heat distribution and pressure application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional fixing device uses a simple nip forming structure, then the device complexity is reduced, but the heat distribution uniformity and pressure distribution deteriorate
Solution Approach 1:
The heat equalizing member is designed with different structural zones: a flat portion at the upstream end for optimal heat conduction, and a bent portion at the downstream end for positioning and pressure distribution. This local differentiation allows each part to perform its specific function optimally, achieving uniform heat distribution without excessive complexity
Solution Approach 2:
The heat equalizing member acts as an intermediary component between the heat source and the recording medium. It receives heat from the heat source and distributes it uniformly across the nip region, mediating the thermal transfer process to eliminate temperature non-uniformity while maintaining a relatively simple overall structure
2Temperature
If the heat equalizing member is positioned too far upstream, then heat distribution improves, but the nip width consistency deteriorates
Solution Approach 1:
The heat equalizing member extends in the conveyance direction (longitudinal dimension) with a specific length that balances heat distribution and nip width control. By optimizing this dimensional parameter, the design achieves both uniform heat distribution and consistent nip width without requiring additional adjustment mechanisms
3Reliability
If pressure is increased to improve fixing quality, then the fixability improves, but the risk of jamming increases
Solution Approach 1:
The bent portion of the heat equalizing member is designed with specific geometric parameters (bend radius, length, position) that optimize the pressure distribution in the nip. These parameter optimizations allow sufficient pressure for good fixability while preventing excessive pressure that would cause jamming, achieving a balanced fixing performance
4Temperature
If the bent portion of the heat equalizing member is made longer, then the heat distribution uniformity improves, but the device complexity and potential for interference increases
Solution Approach 1:
The bent portion of the heat equalizing member has a length that is sufficient to achieve the required heat distribution uniformity, but not excessively long. This partial action approach provides just enough heat equalization functionality while avoiding unnecessary complexity and potential interference with other components
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 enhances the uniformity of heat distribution and pressure application, improving the fixability of toner images while reducing jamming and maintaining a consistent nip width, thus enhancing the overall performance of the image forming process.
Implementation Method 1
a heat equalizing member with a flat portion between the base material and the pressure member... the heat equalizing member has a flat portion between the base material and the pressure member
Implementation Method 2
a fixing device applies heat and pressure to the recording medium carrying the toner image to fix the toner image onto the recording medium
Implementation Method 3
a pressure member that forms a nip with the fixing member... The toner image is fixed onto the recording medium under heat and pressure while the recording medium is conveyed between the fixing rotator and the opposed rotator
Data Source
AI summary
A fixing device is provided that includes a rotatable endless fixing member; a heat source for heating the fixing member; a pressure member that forms a nip with the fixing member; and a nip forming portion that faces the pressure member inside the fixing member and forms the nip; wherein the nip forming portion has a base material and a heat equalizing member, the heat equalizing member has a flat portion between the base material and the pressure member and a bent portion that begins to bend away from the pressure member at an upstream side edge of the base material with respect to a conveyance direction of a recording medium that is configured to be conveyed between the pressure member and the fixing member, and then the bent portion further bends to at least partially hook over a convex part of the base material that is formed at the upstream side of the base material such that an end portion of the bent portion is farther downstream with respect to the conveyance direction of a recording medium than the upstream side edge of the base material.