Double-Layer Electrode for Fixing Device Heat Efficiency
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Solution Overview
Problem
Existing electrodes in image forming apparatuses, particularly in fixing devices, face issues with high electrical resistivity and detachment from resistance heating layers, leading to low heat efficiency and durability concerns due to oxidation and thermal expansion.
Innovation Solution
A double-layered electrode structure is implemented, where a first electrode layer with a low linear expansion coefficient is directly layered on the resistance heating layer, and a second, oxidation-resistant electrode layer with higher Mohs hardness is used as the outermost layer, to minimize detachment and oxidation risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If an electrode formed of a resin layer with conductive filler is used, then the electrode does not need to generate heat, but the electrical resistivity is higher causing low heat efficiency
Solution Approach 1:
The electrode is constructed as a composite structure with a metal base layer providing low electrical resistivity and a resin layer with conductive filler providing insulation and structural support. This composite approach allows the metal layer to conduct electricity efficiently while the resin layer prevents unnecessary heat generation and provides mechanical stability.
Solution Approach 2:
The electrode is divided into multiple functional layers: a metal base layer for electrical conduction and a resin layer with conductive filler for insulation and structural support. This segmentation allows each layer to perform its specific function optimally without interfering with the other.
2Reliability
If an electrode formed of metal with low electrical resistivity is used, then the heat efficiency is improved, but the electrode easily detaches from the resistance heating layer
Solution Approach 1:
The electrode combines a metal base layer for electrical conduction with a resin layer containing conductive filler for adhesion and structural support. The resin layer acts as a bonding interface between the metal electrode and the resistance heating layer, preventing detachment while maintaining electrical conductivity through the metal layer.
Solution Approach 2:
Different regions of the electrode structure have different properties: the metal base layer provides electrical conductivity, while the resin layer provides adhesion and mechanical support. This local differentiation of properties allows the electrode to simultaneously achieve low electrical resistivity and strong adhesion.
3Reliability
If a metal electrode is used, then the electrical conductivity is high, but the electrode is prone to oxidation reducing durability
Solution Approach 1:
The electrode structure combines a metal base layer for electrical conduction with a resin layer containing conductive filler that provides oxidation resistance. The resin layer acts as a protective barrier, shielding the metal layer from oxidative environments while allowing electrical current to pass through via the conductive filler particles.
4Strength
If the linear expansion coefficient of the electrode matches the resistance heating layer, then detachment is reduced, but the electrode material selection is limited
Solution Approach 1:
The electrode is segmented into a metal base layer and a resin layer with conductive filler. The resin layer's linear expansion coefficient can be adjusted to match the resistance heating layer, reducing thermal stress and detachment, while the metal layer provides electrical conductivity. This segmentation decouples the conflicting requirements of adhesion and material selection flexibility.
Solution Approach 2:
The composite electrode structure allows independent optimization of each layer's properties. The resin layer can be formulated with specific polymers and conductive filler combinations to achieve desired thermal expansion characteristics, while the metal layer can be selected from various conductive materials based on electrical performance requirements.
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 durability and electrical conductivity of the electrodes, reducing heat loss and maintaining high heat efficiency by uniformly distributing electric current and resisting thermal expansion and oxidation.
Implementation Method 1
a resistance heating layer that generates heat when an electrical current is applied
Data Source
AI summary
A fixing device includes: a heating rotary member having a heating layer generating heat upon current application; a pressurizing rotary member brought into pressure-contact with an outer circumferential surface of the heating rotary member to form fixing nip, through which a sheet on which unfixed toner image is formed passes for heat fixing; circular electrodes that are circumferentially formed at two respective positions sandwiching a sheet passing region therebetween, on the outer circumferential surface, and feed electrical power to the heating layer, the electrodes are each metallic and formed of at least two electrode layers including a first electrode layer layered directly on the heating layer and a second electrode layer as an outermost layer, linear expansion coefficient difference between the first layer and the heating layer is smaller than that between the second layer and the heating layer, and the second layer is more oxidation-resistant than the first layer.