Composite Heating Roller for Image Fixing
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Solution Overview
Problem
Existing roller fixing devices with thin heating rollers face challenges in achieving both energy savings and effective heat transfer, as high rigid materials like stainless alloy and iron have lower heat conductivity than aluminum, leading to inefficient cooling of non-sheet passing areas when multiple sheets are fed continuously.
Innovation Solution
A fixing device with a cylindrical heating roller having a substrate layer made of high rigid material and a heat conductive layer with higher conductivity than the substrate, where the substrate layer is thinner at both ends and thicker at the center, and the heat conductive layer is thicker at both ends, allowing for efficient heat transfer and energy savings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the heating roller is made thin to decrease heat capacity and improve energy saving performance, then energy efficiency is improved, but the rigidity of the heating roller deteriorates
Solution Approach 1:
The heating roller is constructed as a composite structure with a substrate layer made of high rigid material (stainless alloy or iron) and a heat conductive layer made of aluminum. This composite design allows the roller to maintain both high rigidity from the substrate layer and good heat conductivity from the aluminum layer, while keeping the overall thickness small for energy saving performance.
2Strength
If high rigid material like stainless alloy or iron is used as substrate layer to maintain rigidity, then rigidity is improved, but heat conductivity deteriorates
Solution Approach 1:
The heating roller combines a high rigid substrate layer (stainless alloy or iron) with an aluminum heat conductive layer. The aluminum layer compensates for the poor heat conductivity of the high rigid material, while the substrate layer provides the necessary rigidity. This composite approach resolves the contradiction between rigidity and heat conductivity.
Solution Approach 2:
Different parts of the heating roller have different material properties optimized for their specific functions. The substrate layer uses high rigid material where structural strength is needed, while the heat conductive layer uses aluminum where heat transfer is critical. This local differentiation of material properties allows each region to perform its function optimally.
3Temperature
If a high heat conductive layer is provided around the outer circumferential face to improve heat distribution, then temperature uniformity is improved, but heat transfer speed from non-sheet passing area deteriorates
Solution Approach 1:
The heat conductive layer is designed with non-uniform thickness, being thinner in the non-sheet passing area and thicker in the sheet passing area. This local variation in thickness optimizes heat transfer speed in the non-sheet passing area while maintaining temperature uniformity in the sheet passing area, resolving the contradiction between these two 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 enables rapid and even heat transfer in the width direction, preventing excessive heating of non-sheet passing areas and improving energy efficiency while maintaining the rigidity of the heating roller, thus effectively fixing toner images on sheets.
Implementation Method 1
The heat conductive layer has a heat conductivity higher than the substrate layer. Because heat is transferred through the high heat conductive layer in a width direction, a temperature of the heating roller becomes equal in the width direction.
Implementation Method 2
a fixing device which fixes a toner image transferred on a sheet to the sheet
Data Source
AI summary
A fixing device includes a rotatable cylindrical heating roller, a heat source and a pressing roller. The heat source is arranged in a hollow inner space of the heating roller. The pressing roller is pressed against the heating roller to form a fixing nip through which a sheet is passed in a sheet passing direction. The heating roller has a substrate layer and a heat conductive layer. The substrate layer is formed such that both end portions in a width direction perpendicular to the sheet passing direction are made thinner than a center portion in the width direction, within a sheet passing area through which the sheet is passed. The heat conductive layer is provided around an outer circumferential face of the substrate layer and has a heat conductivity higher than the substrate layer.