Heat Fixing Apparatus Edge Temperature Control
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Solution Overview
Problem
Heat fixing apparatuses face issues with excessive temperature rise at the edge portions when using reduced pressurization conditions, leading to uneven heat distribution and reduced durability due to inadequate heat transmission from the heating member to the pressurization member.
Innovation Solution
A heat fixing apparatus with an endless belt and a heater having a first and second heat generation member, where the resistance value ratio at the edge portions to the center is greater than at the center, combined with a pressure change mechanism to adjust pressure settings, ensuring optimal heat distribution and preventing excessive temperature rise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If pressure is reduced at the edge portions to prevent deflection of the recording material, then the deflection of the recording material is prevented, but the heat transmission from the heating member to the pressurization member becomes insufficient, causing excessive temperature rise at the edge portions
Solution Approach 1:
The patent applies local quality by making the pressurization member have different local characteristics: the edge portions have a larger radius of curvature (less pressurization) to prevent recording material deflection, while the center portion has a smaller radius of curvature (more pressurization) to ensure adequate heat transmission. This spatial variation in pressurization characteristics resolves the contradiction between preventing deflection and maintaining uniform temperature distribution.
Solution Approach 2:
The patent utilizes curvature by designing the pressurization member with a crown shape where the radius of curvature varies across the surface. Specifically, the edge portions have a larger radius of curvature compared to the center portion, creating a spheroidal or curved surface profile that optimizes both mechanical support and thermal contact properties in different regions.
2Ease of manufacture
If the pressurization member is made with light weight and low cost materials, then manufacturing cost is reduced, but the deflection of the pressurization member increases under pressure
Solution Approach 1:
The patent compensates for the dimensional instability caused by using lightweight, low-cost materials by pre-shaping the pressurization member with a crown profile. The larger radius of curvature at the edge portions is designed to account for the expected deflection under pressure, ensuring that the member maintains its functional shape during operation despite being made from less rigid materials.
Solution Approach 2:
The patent applies local quality by creating different curvature characteristics in different regions of the pressurization member. The edge portions have a larger radius of curvature to accommodate greater deflection, while the center has a smaller radius, optimizing the overall performance of the lightweight structure under various loading conditions.
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
The solution effectively prevents excessive temperature rise at the edge portions, maintaining even heat distribution and extending the durability of the fixing member by adjusting the heat proportion of the second heat generation member relative to the first, regardless of the recording material size.
Implementation Method 1
a heating heater 61 has a heat generation resistance layer generating heat by electrification
Data Source
AI summary
The heat fixing apparatus includes a fixing heater and a pressure roller. The fixing heater has a plurality of resistance-type heat generation layers which are different in heat distribution in the longitudinal direction perpendicular to the direction of conveying a recording material. The recording material P is heated when passed through a fixing nip portion formed between the fixing heater and the pressure roller. The pressurization conditions between the fixing heater and the pressure roller can be changed. The heat fixing apparatus includes a fixing member which adjusts the lengthwise heat distribution of the fixing heater by changing the applied current proportion of the plurality of resistance-type heat generation layers according to the pressurization conditions between the fixing heater and the pressure roller.