Heater Temperature Detection with Spring-Loaded Rigid Positioning
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Solution Overview
Problem
The existing temperature detection devices for heat-fixing fixing apparatuses in electrophotographic image forming apparatuses suffer from reduced detection accuracy due to the mechanical properties of the heat-resistant elastic members, which are costly and prone to creep deformation under high temperatures.
Innovation Solution
A temperature detection device with a flexible member supporting a detection element, allowing relative movement in the third direction, and an urging member to maintain accurate positioning of the detection element relative to the heater, using metal plates and resin materials to enhance positional accuracy and thermal responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a heat-resistant elastic member is used to press the detection element against the ceramic heater, then the detection element can maintain contact with the heater, but the detection accuracy is affected by the mechanical properties of the elastic member
Solution Approach 1:
The patent removes the heat-resistant elastic member from the structure and replaces it with a rigid detection-element holding member. This extraction of the problematic elastic component eliminates the source of mechanical property interference while maintaining the necessary contact function through a different mechanism (compression spring acting on a rigid holder rather than an elastic member directly pressing the detection element).
Solution Approach 2:
The patent introduces a compression spring as an intermediary component between the detection-element holding member and the ceramic heater. The spring provides the necessary contact force while the rigid holding member ensures precise positioning. This intermediary approach allows the detection element to maintain stable contact without being directly pressed by an elastic member whose mechanical properties would interfere with measurement accuracy.
2Reliability
If the material of the heat-resistant elastic member is selected to prevent creep deformation and denaturation at high temperatures, then the contact stability is maintained, but the cost increases
Solution Approach 1:
The patent eliminates the heat-resistant elastic member entirely, replacing it with a rigid detection-element holding member made of standard materials. This removes the need to select expensive, specialized high-temperature elastic materials while maintaining the functional requirements through the spring-loaded rigid holder design.
Solution Approach 2:
The patent replaces expensive, specialized heat-resistant elastic materials with standard, more economical materials for the holding member and spring components. The design accepts that these components will be replaced periodically rather than requiring permanent, high-cost materials, thereby reducing overall system cost while maintaining adequate service life.
3Reliability
If the detection element is forced into pressure contact with the ceramic heater by elastic force, then contact is maintained, but the positional accuracy is affected by material creep
Solution Approach 1:
The patent removes the elastic member that causes positional drift through creep, and replaces it with a rigid holding member positioned by mechanical features (positioning protrusions and recesses). This extraction eliminates the source of positional inaccuracy while maintaining contact through the spring mechanism.
Solution Approach 2:
The patent incorporates positioning protrusions and recesses in the rigid holding member and heater holder that pre-establish the correct spatial relationship between the detection element and heater before operation. This preliminary positioning action ensures high positional accuracy is maintained throughout operation, preventing the drift that would occur with elastic members under thermal stress.
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 improves the positional accuracy and thermal responsiveness of the detection element, reducing material costs and maintaining precise temperature detection even under high-temperature conditions.
Implementation Method 1
the flexible member is flexible such that the first holding member and the second holding member are movable relative to each other in the third direction
Implementation Method 2
the first holding member is urged by the urging member toward the heater in the third direction
Data Source
AI summary
A fixing apparatus includes a heater including a heating member, a heater holder configured to hold the heater, a detection element configured to detect a temperature of the heater and disposed at a position that faces the heater in a third direction, a first holding member configured to hold the detection element, an urging member configured to urge the first holding member, a flexible member extending in the first direction and configured to support the first holding member on a first end portion of the flexible member in the first direction, and a second holding member configured to hold a second end portion of the flexible member in the first direction. The flexible member is flexible such that the first holding member and the second holding member are movable relative to each other in the third direction.