Pressing Member Axial Expansion for Uniform Fixing
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Solution Overview
Problem
Existing pressing members for fixing devices in image forming apparatuses face issues with thermal expansion, leading to uneven fixing and potential wrinkles due to increased outer diameter, which affects the quality of the image formed on recording media.
Innovation Solution
A pressing member comprising a cylindrical sleeve with a higher linear expansion coefficient in the axial direction than the core metal, allowing it to extend independently, reducing radial expansion and maintaining a consistent outer diameter, and an elastic layer with air bubbles for thermal expansion management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the elastic layer is fixed to the axial section and thermally expands, then the elastic layer can provide fixing pressure, but the outer diameter of the pressing member increases causing uneven fixing and wrinkles
Solution Approach 1:
The pressing member is divided into three distinct layers: axial section, cylindrical body, and elastic layer. This segmentation allows each layer to perform its specific function independently - the axial section provides structural support, the cylindrical body accommodates thermal expansion axially, and the elastic layer provides fixing pressure, thereby preventing outer diameter increase and ensuring uniform fixing.
Solution Approach 2:
The patent redirects the thermal expansion of the elastic layer from the radial direction (which would increase outer diameter) to the axial direction (where the cylindrical body allows movement). By providing axial play between the cylindrical body and axial section, the design enables thermal expansion to occur in a different dimension, maintaining consistent outer diameter and uniform fixing quality.
2Manufacturing precision
If the elastic layer is allowed to expand axially, then outer diameter remains constant, but the structure becomes more complex with movable cylindrical body
Solution Approach 1:
The cylindrical body is designed with movable capability relative to the axial section, allowing it to dynamically adjust its position axially in response to thermal expansion of the elastic layer. This dynamic design enables the system to automatically maintain constant outer diameter without requiring complex control mechanisms, achieving precision through adaptive structural behavior.
Solution Approach 2:
The patent applies different properties to different parts: the axial section has high structural rigidity, the cylindrical body has controlled movability with specific clearance, and the elastic layer has elastic properties. This local differentiation of qualities allows the system to achieve overall precision while keeping each component relatively simple in design.
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 the variation in transport speed and pressure, minimizing uneven fixing and wrinkles, thereby enhancing the quality of the image formed on the recording medium.
Implementation Method 1
when the elastic layer thermally expands, the outer diameter of the pressing member for fixing may increase
Implementation Method 2
an elastic layer with air bubbles for thermal expansion management
Data Source
AI summary
A pressing member for fixing includes: an axial section; a cylindrical body that includes the axial section internally inserted, rotates following rotation of the axial section, and is extendable in an axial direction relative to the axial section; and an elastic layer that is stacked on an outer circumference of the cylindrical body.