Pressure Roller with Reverse Camber and Dual Elastic Layers
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Solution Overview
Problem
In image forming apparatus, the existing film heating systems in fixing devices often cause wrinkles in recording materials due to temperature unevenness and conveyance speed differences along the pressure roller, which are not effectively addressed by void-containing elastic layers with reverse camber shapes, as they absorb differences in sheet conveyance force leading to unstable control.
Innovation Solution
A pressure roller with a metal core, a void-containing first elastic layer, and a second elastic layer with higher microhardness (25-50 degrees) is used, where the outer diameter of the end portions is larger than the middle portion, maintaining circumferential length and creating a desired difference in conveyance force to prevent wrinkles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If a void-containing elastic layer with reverse camber shape is used in the pressure roller, then heat insulating effect is improved, but sheet conveyance speed control deteriorates due to absorbed elasticity differences
Solution Approach 1:
The pressure roller is divided into multiple elastic layers with different properties: a first elastic layer with voids for heat insulation and a second elastic layer without voids for stable sheet conveyance. This segmentation allows each layer to perform its specific function without interfering with the other, resolving the contradiction between heat insulation and conveyance control.
Solution Approach 2:
Different regions of the pressure roller are assigned different properties: the first elastic layer provides heat insulation throughout, while the second elastic layer with higher microhardness provides localized stable conveyance force. The reverse camber shape is applied selectively to create higher conveyance force at end portions where it is most needed, without compromising overall heat insulation.
2Force
If the outer diameter of end portions is made larger than the middle portion (reverse camber shape), then sheet conveyance force at ends is improved, but temperature unevenness along the roller worsens
Solution Approach 1:
The pressure roller is segmented into multiple elastic layers with different functions. The reverse camber shape is applied to the overall structure to provide higher conveyance force at ends, while the heat generating portion is separated into a distinct layer that maintains uniform heat distribution, preventing temperature unevenness despite the diameter variation.
Solution Approach 2:
The pressure roller uses a composite structure with multiple elastic layers having different properties. The first elastic layer with voids provides heat insulation, while the second elastic layer provides mechanical stability. This composite approach allows the reverse camber shape to improve conveyance force without compromising thermal uniformity.
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 suppresses wrinkles by maintaining a consistent circumferential length and conveyance force difference between the middle and end portions, enhancing the stability of sheet conveyance and fixing performance.
Implementation Method 1
it is effective to use an elastic sponge rubber layer formed by foaming silicone rubber so that a pressure roller has a heat insulating effect
Implementation Method 2
rubber itself has a large elasticity, and hence a difference in sheet conveyance force between the middle portion and the end portions is absorbed due to deformation of the rubber
Data Source
AI summary
The roller for use in a fixing device, includes a metal core, a first elastic layer formed on an outer side of the metal core, the first elastic layer having voids, and a second elastic layer formed on an outer side of the first elastic layer, the second elastic layer having a microhardness higher than a microhardness of the first elastic layer, in which an outer diameter of an end portion of the roller is larger than an outer diameter of a middle portion of the roller in a longitudinal direction of the roller, and in which the microhardness of the second elastic layer is 25 degrees or more and 50 degrees or less.