Temperature Sensor Spring Holder Structure for Accurate Heater Contact
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Solution Overview
Problem
The existing image forming apparatuses face issues with the erroneous assembly of compression coil springs that press temperature sensors against heaters, leading to inaccurate temperature detection and increased defect rates due to oblique assembly, which is difficult to detect visually.
Innovation Solution
A heating device with a sensor holder and compression coil spring design where the first end coil of the spring is inserted into a boss with a fixing portion and the active coil is spaced apart, preventing oblique assembly and ensuring consistent contact pressure of the temperature sensor on the heater.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the compression coil spring is assembled without a specific structure to prevent oblique insertion, then the assembly process is simple, but the spring may be erroneously assembled obliquely leading to inaccurate temperature detection
Solution Approach 1:
The boss is designed with an asymmetric profile where one side has a larger diameter than the other side. This asymmetric structure creates a unique insertion path that prevents the compression coil spring from being inserted obliquely, ensuring accurate alignment and assembly precision without requiring complex additional components
Solution Approach 2:
The boss acts as an intermediary component between the sensor holder and the compression coil spring. By incorporating the asymmetric boss into the sensor holder structure, it mediates the insertion process and guides the spring into the correct position, preventing erroneous assembly while maintaining structural simplicity
2Ease of operation
If the compression coil spring can be inserted freely without guidance, then the assembly operation is easy, but the temperature sensor contact pressure becomes inconsistent
Solution Approach 1:
The asymmetric boss structure provides a unique insertion path that naturally guides the compression coil spring into the correct position. This design maintains ease of operation by requiring only a single insertion motion while ensuring consistent contact pressure through precise alignment, eliminating the need for complex guidance mechanisms
3Device complexity
If no specific structure is provided to prevent spring misalignment, then the device structure remains simple, but visual detection of erroneous assembly becomes difficult
Solution Approach 1:
The asymmetric boss structure creates a visually distinguishable correct assembly position. The unequal diameter sides of the boss provide clear visual cues that allow operators to easily identify whether the compression coil spring has been inserted correctly, significantly improving defect detection capability while maintaining structural simplicity
Solution Approach 2:
The asymmetric geometry of the boss creates visible differences in the assembled structure that serve as visual indicators. The unique fit of the spring into the asymmetric boss produces observable alignment features that make erroneous assembly easily detectable without requiring complex detection systems
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 design prevents erroneous assembly of the compression coil spring, maintaining accurate temperature detection and reducing product defect rates by ensuring proper contact pressure and alignment of the temperature sensor.
Implementation Method 1
a compression coil spring pressing the temperature sensor against the heater
Data Source
AI summary
A heating device includes a heater, a temperature sensor detecting a temperature of the heater, a compression coil spring having a first end coil, a second end coil, and an active coil between the first and second end coils, a receiver receiving the second end coil, and a sensor holder including a holding portion and a boss. The holding portion holds the temperature sensor at one side of the sensor holder. The boss supports the first end coil at another side of the sensor holder. The first end coil is inserted into the boss in an insertion direction. The boss has a fixing portion contacting an inner face of the first end coil, and the active coil is spaced apart from the fixing portion in the insertion direction.