Heater Design for Image Heating Apparatus Temperature Uniformity
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Solution Overview
Problem
Existing image heating apparatuses face challenges in achieving both small temperature unevenness and high surge resistance, particularly when using a cylindrical film heater with a limited number of heating elements per unit area, which can lead to increased resistance to surges and reduced surge resistance due to high sheet resistance materials.
Innovation Solution
A heater design with multiple rows of heating elements arranged between conductors, where the ratio of the sum of heating element widths to the total width is between 0.54 and 1, ensuring both reduced temperature unevenness and enhanced surge resistance by optimizing the shape and arrangement of heating elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the pitch between adjacent heating elements is reduced to increase the number of heating elements, then temperature distribution unevenness is suppressed, but sheet resistance increases and surge resistance decreases
Solution Approach 1:
The heating elements are divided into multiple independent segments arranged in parallel between the conductors. By segmenting the heating structure into multiple discrete elements rather than a continuous structure, the patent achieves both improved temperature distribution through increased element count and maintained surge resistance through parallel configuration that limits total resistance
Solution Approach 2:
The patent optimizes the width of heating elements and the pitch between them to achieve a specific ratio R (0.3 ≤ R < 0.5). This parameter optimization allows sufficient number of heating elements for temperature uniformity while controlling total resistance to maintain surge resistance. The conductor width and heating element width are specifically designed to achieve the desired resistance characteristics
2Temperature
If the number of heating elements per unit area is increased to reduce temperature rise in non-sheet-feeding region, then temperature distribution becomes more uniform, but total resistance decreases and surge resistance is reduced
Solution Approach 1:
The patent transitions from considering only the number of heating elements to optimizing the two-dimensional arrangement including element width, pitch, and conductor width. By introducing the ratio R that combines these dimensional parameters, the solution achieves temperature uniformity through proper spatial distribution while maintaining surge resistance through controlled total resistance
Solution Approach 2:
The patent establishes specific parameter ranges: ratio R (0.3 ≤ R < 0.5), number of heating elements (5-15), and conductor width (15-30 mm). These parameter changes enable simultaneous achievement of temperature uniformity and surge resistance by balancing element density with total resistance characteristics
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 temperature unevenness while maintaining high surge resistance, ensuring reliable operation and image quality in image heating processes.
Implementation Method 1
a plurality of heating elements arranged between the first conductor and the at least one second conductor and electrically connected in parallel to the first conductor and the at least one second conductor
Data Source
AI summary
A heater for use in an image heating apparatus includes a substrate, first and second conductors provided on the substrate, and heating elements. The heating elements are arranged between, and electrically connected in parallel to, the first and second conductors. When n denotes a number of heating elements, connected to one second conductor, in one row of the heating elements, a width L denotes a sum (n×Wh) of widths, as seen in a longitudinal direction of the substrate, of shortest current paths of all respective heating elements connected to the one second conductor plus a sum of widths, as seen in the longitudinal direction, of respective gaps between adjacent shortest current paths, and a ratio R denotes a ratio of the sum (n×Wh) of widths to the width L, the heating elements are configured so as to satisfy 0.54≤the ratio R<1.