Heating Unit Temperature Sensor Accuracy via Heat Conductive Members
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Solution Overview
Problem
In heating units for electrophotographic image forming apparatuses, direct contact of temperature detecting members with ceramic heaters leads to inaccurate temperature detection due to temperature unevenness caused by resistance heating elements.
Innovation Solution
Incorporating a first heat conductive member between the heater and a holder, and a second heat conductive member positioned to correspond to openings in the first member, allowing the temperature sensor to contact the second member's surface for improved temperature detection, while the second member provides enhanced heat conductivity to the sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the temperature detecting member is directly brought into contact with the back surface of the heater, then the structure is simple, but accurate temperature detection cannot be achieved due to temperature unevenness
Solution Approach 1:
A heat conductive member is introduced as an intermediary between the heater and the temperature detecting member. This mediator has higher heat conductivity than the heater substrate, enabling it to collect and transfer heat from different regions of the heater to the temperature sensor, thereby achieving accurate temperature detection while maintaining structural simplicity
Solution Approach 2:
The heat conductive member includes a through-hole that extends in the thickness direction, creating a three-dimensional heat conduction path. The temperature detecting member is positioned to detect temperature through this hole, allowing temperature measurement at multiple points and providing comprehensive thermal information
2Measurement precision
If a heat conductive member with through-hole is used, then temperature detection accuracy is improved, but the device structure becomes more complex
Solution Approach 1:
The heat conductive member serves multiple functions simultaneously: it acts as a heat conduction path from the heater to the temperature sensor, provides structural support for the temperature detecting member, and creates a through-hole pathway that enables both temperature detection and potential other functions. This multi-functionality reduces the need for additional separate components
3Power
If the resistance heating element is provided on the substrate, then heating function is achieved, but temperature unevenness occurs between portions near and apart from the heating element
Solution Approach 1:
The heat conductive member has spatially varying heat conductivity characteristics, with higher heat conductivity regions positioned to collect heat from areas near the resistance heating element and lower heat conductivity regions in other areas. This local quality variation enables the member to effectively collect heat from the heating element while distributing it uniformly to the temperature sensor
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 enables accurate temperature detection by minimizing the impact of temperature unevenness and ensuring effective heat conduction to the sensor, thereby improving the responsiveness of the temperature detection system.
Implementation Method 1
the first heat conductive member having a heat conductivity higher than that of the substrate
Implementation Method 2
the second heat conductive member disposed at a position at least corresponding to the opening when viewed in an orthogonal direction orthogonal to the first opposite surface
Data Source
AI summary
A heating unit includes a heater, a temperature sensor, an endless belt, a holder, a first heat conductive member, and a second heat conductive member. The first heat conductive member includes a first heater-side surface facing the heater, a first opposite surface, and an opening. The first heat conductive member has a heat conductivity higher than that of the substrate. The second heat conductive member includes a second heater-side surface facing the heater and a second opposite surface. The second heat conductive member is positioned at a position corresponding to the opening when viewed in an orthogonal direction orthogonal to the first opposite surface. The temperature sensor is in contact with the second opposite surface of the second heat conductive member.