Non-Uniform Heat Generating Resistor for Image Fixing
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Solution Overview
Problem
Image forming apparatuses face excessive temperature rises in non-paper-passage areas when printing A4 size paper, potentially damaging the film or pressure roller, especially when the paper is fed in one edge-aligned mode, due to the heat generating resistor's design optimized for LTR size paper, leading to reduced fixing properties and increased energy consumption.
Innovation Solution
The image forming apparatus features a heat generating resistor with a longer length perpendicular to the paper conveyance direction and varying resistance per unit length, where the edge areas have lower resistance than the center area, allowing for effective temperature control and reduced heat generation in non-paper-passage areas without compromising the fixing properties of LTR size paper.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the heat generating resistor is designed with length optimized for LTR size paper, then the fixing property for LTR size paper is improved, but the temperature rise in non-paper-passage areas occurs when A4 size paper is fed
Solution Approach 1:
The heat generating resistor is designed with non-uniform resistance distribution, where the resistance per unit length varies along the longitudinal direction. Specifically, the resistance per unit length is set to be smaller in edge areas than in center areas, creating local quality differences that suppress temperature rise in non-paper-passage areas while maintaining effective heating in paper-passage areas.
2Productivity
If the temperature of the fixing unit is excessively raised to increase printing speed, then the printing speed is improved, but the film or pressure roller may be damaged
Solution Approach 1:
The resistance per unit length of the heat generating resistor is changed as a parameter along its longitudinal direction. By setting the resistance per unit length to be smaller in edge areas than in center areas, the heat generation is optimized to prevent excessive temperature rise that could damage the film or pressure roller, while still achieving sufficient heating speed for high printing speed operation.
3Temperature
If the heat generating quantity is reduced to suppress temperature rise in non-paper-passage areas, then the temperature control is improved, but the fixing property may deteriorate
Solution Approach 1:
The heat generating resistor implements local quality by having different resistance per unit length in different longitudinal areas. The edge areas have smaller resistance per unit length to suppress temperature rise in non-paper-passage areas, while the center areas have larger resistance per unit length to maintain sufficient heat generation for proper fixing property.
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 effectively suppresses excessive temperature rises in non-paper-passage areas during A4 size paper printing, maintaining the fixing properties for LTR size paper and reducing energy consumption by optimizing the heat generating resistor's design.
Implementation Method 1
a heater having a heat generating resistor provided on a substrate thereof... thermally fixes a tone image formed on a recording paper by the heat from the heater applied via the fixing film onto a recording paper
Data Source
AI summary
In an image forming apparatus, the overall length of a heat generating resistor is set longer than the width of a recording paper, which is the greatest of widths of standard size recording papers that can be used on the image forming apparatus. An electrical resistance of an edge area of the heat generating resistor per unit length is set smaller than that of a center area of the heat generating resistor. The position of a boundary between the center area and the edge area is set so that the position of the side edge of the recording paper whose width is the greatest exists within the edge area and so that if the recording paper having the second greatest width is fed by a one edge-aligned paper feeding method, the position of the side edge of a recording paper whose width is the greatest of the widths of the standard size recording papers that can be used on the image forming apparatus except the width of the recording paper that is the greatest thereof is set at a position within the center area.