Fixing Device Temperature Control via Degaussing Coils
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Solution Overview
Problem
Existing image forming apparatuses face challenges in preventing excessive temperature increases at non-conveyance portions of fixing members due to limited flexibility and installation positions of temperature sensors, leading to inaccurate temperature detection and potential damage from excessive heat.
Innovation Solution
A fixing device with multiple temperature detectors positioned on the pressing member to detect temperatures at various points, allowing for precise control of power supplied to degaussing coils, ensuring efficient and reliable prevention of excessive temperature increases at non-conveyance portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a contact-type thermistor is provided to detect temperature at the edge of the fixing member, then temperature detection is achieved, but a mark remains on the fixing member surface that appears on the fixed image
Solution Approach 1:
The patent introduces the pressing member as an intermediary between the temperature sensor and the fixing member. The temperature sensor detects temperature at the edge of the pressing member, which indirectly reflects the temperature at the corresponding edge of the fixing member. This intermediary approach allows temperature detection without direct contact between the sensor and the fixing member surface, thereby preventing mark formation on the fixing member that would appear on the fixed image.
2Temperature
If multiple pairs of degaussing coils are provided at positions corresponding to non-conveyance portions, then excessive temperature increase is prevented, but device complexity increases
Solution Approach 1:
The patent applies local quality by providing degaussing coils only at specific positions corresponding to non-conveyance portions of the fixing member, rather than uniformly across the entire fixing member. The pressing member includes non-conveyance portions at its both ends where degaussing coils are strategically placed to generate magnetic fluxes that prevent excessive temperature increase at these specific locations, while leaving other areas without degaussing coils to maintain simpler structure.
3Adaptability or versatility
If temperature sensors are installed at multiple positions on the pressing member, then temperature detection flexibility is improved, but device complexity increases
Solution Approach 1:
The patent makes the pressing member multi-functional by integrating both the pressing function and the temperature detection function into a single component. Temperature sensors are embedded in the pressing member to detect temperatures at multiple positions, allowing the pressing member to serve dual purposes: applying pressure to the fixing member and providing temperature information for control. This universal approach improves temperature detection flexibility without proportionally increasing device 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
The solution provides a higher degree of flexibility in temperature detection and control, effectively preventing excessive temperature rises at non-conveyance portions, ensuring reliable image fixing and reducing the risk of temperature-related damage.
Implementation Method 1
a fixing device employing an electromagnetic induction heating method using degaussing coils
Implementation Method 2
an induction heating unit provided with an exciting coil and multiple pairs of degaussing coils positioned opposite the exciting coil
Implementation Method 3
multiple temperature detectors to detect a temperature at multiple positions on a surface of the pressing member in a width direction thereof
Implementation Method 4
a heating member including a heating layer to heat the fixing member, an exciting coil provided opposite the heating member to generate magnetic fluxes to inductively heat the heating layer
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A fixing device (19) including a fixing member (20) to melt a toner image to fix the toner image to a recording medium, a pressing member (30) pressed against the fixing member (20) to form a nip to where the recording medium is conveyed, multiple temperature detectors (40A; 40B; 40C; 40D) to detect a temperature at multiple positions on a surface of the pressing member (30) in a width direction thereof, a heating member (20) including a heating layer (21) to heat the fixing member (20); an exciting coil (26) to generate magnetic fluxes to inductively heat the heating layer, and one or more pairs of degaussing coils (27A; 27B; 27C) to generate magnetic fluxes to degauss the magnetic fluxes generated by the exciting coil (26). An amount of power supplied to the one or more pairs of degaussing coils (27A; 27B; 27C) is controlled based on a result detected by each of the multiple temperature detectors (40A; 40B; 40C; 40D).