Heater Resistance Block Design for Fixing Member Temperature Uniformity
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Solution Overview
Problem
Existing image forming apparatuses face issues with temperature inconsistencies in the fixing member due to variations in sheet size and conveying position, leading to potential overheating at the end portions of resistance blocks.
Innovation Solution
The heater design includes resistance blocks with specific arrangements of resistance elements and power feed electrodes, where adjacent blocks have increased intervals and targeted resistance elements with higher heat generation to maintain consistent temperature distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resistance blocks are arranged at larger intervals to prevent current leakage, then electrical reliability is improved, but heating uniformity deteriorates at boundary regions
Solution Approach 1:
The patent applies local quality by differentiating the heat generation amounts of specific resistance elements based on their positions. Resistance elements at boundary regions (adjacent to power feed electrodes) are designed with different heat generation characteristics compared to internal resistance elements, allowing localized compensation for the heating insufficiency caused by larger intervals between resistance blocks.
2Temperature
If resistance elements at end portions have larger heat generation amounts to prevent insufficient heating, then heating uniformity is improved, but temperature control deteriorates causing potential overheating
Solution Approach 1:
The patent applies parameter changes by varying the heat generation amounts of resistance elements based on their positions and the selected operation mode (full operation vs. end operation). The control unit adjusts which resistance blocks receive power and at what levels, dynamically changing the operational parameters to match the actual sheet position and size, thereby maintaining temperature control while ensuring heating uniformity.
3Adaptability or versatility
If the heater is designed to handle variations in sheet size and position, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the heater into multiple independently controllable resistance blocks, each with multiple resistance elements. This segmentation allows the control unit to selectively activate only the necessary portions of the heater based on sheet size and position, achieving adaptability without requiring a completely complex redesign of the entire heating system.
Solution Approach 2:
The patent applies dynamics by implementing a control unit that dynamically selects and activates specific resistance blocks based on real-time sheet size and position information. The system transitions between different operational states (full operation, end operation, etc.), adapting the heater's configuration to match the actual processing conditions, thereby achieving versatility with manageable complexity.
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 ensures that the fixing member maintains appropriate temperatures across varying sheet sizes and positions, preventing overheating and ensuring effective toner fixation.
Implementation Method 1
The plurality of resistance blocks 60 each include a plurality of resistance elements 6 arranged at a first interval in a main direction D1
Data Source
AI summary
In order to avoid a situation where a temperature of a part of a fixing member becomes an inappropriate temperature due to variations in a size or conveying position of a sheet, a plurality of resistance blocks include a target block and an adjacent block provided next to the target block. A plurality of resistance elements of the target block include one or a plurality of end portion resistance elements and a target resistance element. The end portion resistance element is positioned at an end portion of the target block on a side of the adjacent block. The target resistance element is positioned next to the end portion resistance element. When power is supplied to the target block, a heat generation amount of the target resistance element is larger than that of the one end portion resistance element or of each of the plurality of end portion resistance elements.