Pressing Roller Elastic Layer Thermal Expansion Control
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Solution Overview
Problem
The existing image heating devices in electrophotographic printers face issues with non-sheet-passing portion temperature rise and fluctuations in recording material conveyance speed, leading to image quality problems like blur and trailing end density increase due to thermal expansion of the pressing roller's elastic layer.
Innovation Solution
An image heating device with a pressing roller featuring an elastic layer made of thermosetting silicon rubber containing thermal conductive fillers and resin microballoons, with pore portions connected by pore connecting portions, providing thermal conductivity within the range of 0.15 W/mK to 0.5 W/mK to manage temperature rise and conveyance speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a sponge type elastic layer with high heat insulating property is used for the pressing roller, then the degree of non-sheet-passing portion temperature rise increases, but the thermal expansion is reduced compared to solid type elastic layer
Solution Approach 1:
The elastic layer is designed with non-uniform foam cell structure where cell density and size vary through the thickness. The region near the heater has different cellular characteristics than the outer region, creating local thermal conductivity variations that balance heat insulation with heat dissipation to control both temperature rise and thermal expansion in different zones
Solution Approach 2:
The elastic layer uses a composite foam structure combining polymer matrix with controlled void distribution. This composite structure provides both the heat insulating property needed to reduce temperature rise and the thermal conductivity pathways needed to control thermal expansion through optimized cell wall composition and arrangement
2Temperature
If the thermal conductivity of the elastic layer is increased to reduce non-sheet-passing portion temperature rise, then the degree of thermal expansion increases
Solution Approach 1:
The foam cell structure is designed with spatially varying properties where regions experiencing higher temperature gradients have different cell densities and wall thicknesses compared to cooler regions. This local differentiation allows heat to be dissipated where needed while maintaining overall thermal insulation to minimize thermal expansion
Solution Approach 2:
The thermal conductivity of the elastic layer is precisely controlled within a specific range (0.1-0.5 W/mK) by adjusting foam cell parameters such as cell size, cell wall thickness, and porosity. This parameter optimization achieves the balance between reducing temperature rise and controlling thermal expansion
3Temperature
If a solid type elastic layer with high thermal conductivity is used, then the non-sheet-passing portion temperature rise is reduced, but the degree of thermal expansion becomes large
Solution Approach 1:
Instead of using solid elastic material, a foam structure with controlled porosity is employed. The porous structure provides thermal insulation to reduce temperature rise while the cell walls and struts create thermal pathways that limit overall thermal expansion. The pore size, distribution, and connectivity are optimized to achieve the desired thermal behavior
Solution Approach 2:
The foam elastic layer acts as a composite material combining the polymer matrix with air-filled voids. This composite structure provides a thermal conductivity lower than solid material but sufficient to control temperature rise, while the flexible foam structure accommodates thermal expansion better than rigid solid material
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 solution effectively reduces non-sheet-passing portion temperature rise and conveyance speed fluctuations, enabling faster image heating processes while maintaining image quality by controlling thermal expansion and heat dissipation.
Implementation Method 1
the elastic layer includes a thermosetting silicon rubber containing a thermal conductive filler
Implementation Method 2
the thermosetting silicon rubber includes pore portions formed with resin microballoons
Data Source
AI summary
An image heating device for heating a toner image while nip-conveying a recording material, in a nip, on which the toner image is carried, includes a heating member; and a pressing roller, including an elastic layer, for forming the nip in contact with the heating member. The elastic layer of the pressing roller includes a thermosetting silicon rubber containing a thermal conductive filler. The thermosetting silicon rubber includes pore portions formed with resin microballoons and a pore connecting portion for connecting the pore portions. The elastic layer has a thermal conductivity of 0.15 W/mK to 0.5 W/mK.