Heater Support Member Prevents Cracking in Image Heating Apparatus
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Solution Overview
Problem
Conventional image heating apparatuses face issues with heater cracking due to abnormal temperature rises, which can occur when the thermosensitive element fails to respond promptly, leading to increased stress on the heater holder, and the existing reinforcement methods are insufficient in preventing cracking, especially when the heater sinks into the holder.
Innovation Solution
An image heating apparatus with a heater support member that provides a clearance from the thermosensitive element, which receives the load when the holder softens, reducing stress on the heater and preventing sinking, thereby extending the time for the thermostatic switch to operate and preventing cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the thermosensitive element is fitted close to the heater to detect temperature rapidly, then the response speed improves, but the heater cracking risk increases due to stress concentration
Solution Approach 1:
A support portion is introduced as an intermediary element between the thermosensitive element and the heater. This support portion receives the load from the thermosensitive element before it can be transmitted to the heater, thereby preventing stress concentration and cracking while maintaining the thermosensitive element's proximity to the heater for rapid temperature detection
Solution Approach 2:
The support portion is positioned in advance to provide cushioning protection. When the holder softens due to abnormal heat generation, the support portion is already in place to receive the load and prevent the thermosensitive element from directly contacting and damaging the heater
2Stability of the object's composition
If the holder rigidity is increased to prevent deformation, then the structural stability improves, but the heater sinking prevention becomes insufficient when abnormal heat generation occurs
Solution Approach 1:
The support portion acts as a mediator that provides additional support to the heater when the holder softens. Even though the holder maintains its structural stability through rigidity, the support portion compensates for the loss of support capability when abnormal heat generation causes the holder to soften, preventing heater sinking
Solution Approach 2:
The support portion changes its load-bearing state based on temperature conditions. During normal operation, the holder bears the load. When abnormal heat generation occurs and the holder softens, the support portion transitions to bearing the load, thereby maintaining heater position stability under varying thermal conditions
3Strength
If the hole for thermosensitive element is reinforced with rib structure, then the holder strength at hole position improves, but the heater cracking prevention remains insufficient
Solution Approach 1:
The support portion serves as a critical intermediary that directly prevents heater cracking. While the rib structure reinforces the holder at the hole position, it only addresses holder strength. The support portion additionally addresses heater protection by receiving load and preventing stress transmission to the heater
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 effectively prevents heater cracking by distributing the load and reducing stress, ensuring the thermostatic switch operates before the heater fails, thus ensuring safety and prolonging its operational life.
Implementation Method 1
a heater having a substrate and a heat generating resistor provided on the substrate
Implementation Method 2
a spring that urges the thermosensitive element toward the heater
Implementation Method 3
a thermosensitive element that senses heat from the heater
Data Source
AI summary
The invention prevents cracking of heater that may occur when a fixing device becomes uncontrollable and provides an image forming apparatus that is advantageous from the viewpoint of recycling of parts. A heater support member that supports a heater during abnormal temperature rise is provided at a position at which a heater holder deforms greatly when abnormal temperature rise of the heater occurs.