Heating Member Curved Portion Warpage Reduction
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Solution Overview
Problem
Conventional fixing devices in image forming apparatuses face issues with heat distribution and warpage due to uneven heat generation, leading to increased warm-up time and potential mechanical stress, particularly when the heating member is integrated into the nip portion, affecting the rigidity and heat capacity.
Innovation Solution
A fixing device with a heating member featuring a curved portion that follows the inner circumferential surface of a belt member, a bent portion to prevent oil scraping, and a heat generation pattern with varying heat generation regions, where the heat generation amount is greater on the upstream side than the downstream side in the moving direction, reducing thermal expansion differences and warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the heating member is integrated into the nip portion to reduce warm-up time, then the warm-up time is reduced, but warpage occurs due to uneven heat generation and thermal expansion
Solution Approach 1:
The heat generation amount is made non-uniform along the moving direction of the belt member, with the upstream side generating more heat than the downstream side. This local variation in heat generation compensates for thermal expansion differences and prevents warpage while maintaining reduced warm-up time.
Solution Approach 2:
The heat generation parameter is changed from uniform to non-uniform distribution along the belt member's moving direction. By adjusting the heat generation amount in different regions (upstream vs downstream), the thermal expansion is balanced and warpage is prevented.
2Quantity of substance
If the heating member is disposed in the nip portion, then heat capacity is reduced, but mechanical stress increases due to warpage
Solution Approach 1:
The heat generation is localized with higher intensity on the upstream side and lower intensity on the downstream side. This non-uniform heat distribution reduces overall heat capacity while preventing warpage-induced mechanical stress through compensatory thermal expansion.
3Manufacturing precision
If the heating member generates heat uniformly, then heat distribution is even, but warpage occurs due to thermal expansion differences
Solution Approach 1:
Instead of uniform heat distribution, the invention implements non-uniform heat generation with the upstream side producing more heat than the downstream side. This local quality variation compensates for thermal expansion differences and prevents warpage.
Solution Approach 2:
The heat generation pattern is made asymmetric along the moving direction of the belt member, with the upstream side generating more heat than the downstream side. This asymmetric heat distribution counteracts the symmetric thermal expansion that would otherwise cause warpage.
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 reduces warpage and maintains reduced warm-up time by optimizing heat distribution and mechanical stress, ensuring efficient operation and longevity of the fixing device.
Implementation Method 1
a heat generation portion that is provided in the curved portion, generates heat upon energization, and heats the belt member
Data Source
AI summary
A fixing device includes a belt member that moves in a circulating manner, a pressure member that is disposed to be in contact with an outer circumferential surface of the belt member, and pressurizes a recording material on which an image is formed, and a heating member. The heating member includes a curved portion that is curved along an inner circumferential surface of the belt member and is in contact with the inner circumferential surface, a bent portion that is bent from an upstream side end portion of the curved portion in a moving direction of the belt member and is separated from the inner circumferential surface, and a heat generation portion that is provided in the curved portion and heats the belt member. A generated heat amount in the curved portion on the upstream side is larger than that in the curved portion on a downstream side.