Heat-Fixing Device Frequency Control for Uniform Temperature
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Solution Overview
Problem
Electromagnetic induction heating methods in heat-fixing devices for image forming apparatuses face challenges in achieving uniform temperature distribution due to variations in the thickness and electric resistivity of the heating member's base layer, leading to inconsistent fixing performance.
Innovation Solution
A heat-fixing device with a rotatable member having an electroconductive layer and a helical coil, where temperature detecting elements at central and end portions monitor temperature differences to adjust the frequency of the AC current, ensuring a predetermined temperature distribution across the member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If electromagnetic induction heating method is used to heat the heating member, then the rate of temperature rise and heat supplying efficiency are improved, but the temperature distribution becomes non-uniform due to manufacturing variations in base layer thickness and electric resistivity
Solution Approach 1:
The patent applies parameter changes by adjusting the frequency of the AC current supplied to the exciting coil based on detected temperature distribution. The frequency is varied to control the depth and pattern of heat generation within the heating member, allowing compensation for manufacturing variations in base layer thickness and electric resistivity. This dynamic parameter adjustment transforms the fixed-frequency heating approach into an adaptive system that maintains uniform temperature distribution despite material variations.
Solution Approach 2:
The patent implements feedback control by using temperature detecting elements to monitor the temperature distribution across the heating member and using this information to adjust the AC current frequency. The temperature detection system provides real-time information about non-uniformities, and the control system responds by modifying the heating frequency to correct these non-uniformities, creating a closed-loop control system that maintains consistent temperature distribution.
2Ease of manufacture
If the base layer thickness and electric resistivity vary due to manufacturing differences, then the electromagnetic induction heating effectiveness changes, but the temperature distribution uniformity deteriorates
Solution Approach 1:
The patent compensates for manufacturing variations by dynamically changing the AC current frequency parameter. Instead of requiring tight control of base layer thickness and resistivity during manufacturing, the system adjusts the heating frequency to account for these variations. This allows greater manufacturing flexibility while maintaining consistent temperature distribution, as the frequency adjustment compensates for the effects of material property variations.
Solution Approach 2:
The patent applies local quality by adjusting the heating frequency based on local temperature conditions detected at different positions across the heating member. Different regions with different thickness or resistivity characteristics receive customized heating frequencies to achieve uniform temperature distribution, rather than applying a uniform frequency across the entire heating member.
3Manufacturing precision
If frequency control is added to adjust temperature distribution, then temperature uniformity is improved, but device complexity increases
Solution Approach 1:
The patent achieves temperature uniformity by adjusting a single parameter - the frequency of the AC current - rather than requiring multiple control elements. This single-parameter control approach improves temperature distribution uniformity while minimizing the increase in device complexity, as it only requires a frequency-adjustable power source and temperature detection system.
Solution Approach 2:
The patent uses a feedback control system with temperature detecting elements that monitor temperature distribution and provide signals for frequency adjustment. This feedback mechanism automatically corrects temperature non-uniformities without requiring complex manual intervention or multiple control elements, achieving improved temperature uniformity with relatively simple added 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
This approach ensures a uniform and consistent heat distribution along the length of the heating member, improving the fixing performance by compensating for manufacturing variations in thickness and resistivity, thereby maintaining a stable temperature for image fixation.
Implementation Method 1
The electroconductive layer generates heat through electromagnetic induction heating by the magnetic flux resulting from the AC current
Implementation Method 2
magnetic flux resulting from the AC current caused to flow through the coil
Data Source
AI summary
A fixing device includes: a rotatable member including an electroconductive layer; a helical coil having a helical axis direction along a generatrix direction of the rotatable member; a magnetic member not forming a loop outside the electroconductive layer; a frequency setting portion for setting a frequency of an AC current caused to flow through the coil; and a temperature detecting portion for detecting a temperature of the rotatable member, including a first temperature detecting member and a second temperature detecting member. The electroconductive layer generates heat through electromagnetic induction heating by magnetic flux resulting from the AC current, and an image is fixed on a recording material by heat of the rotatable member. The frequency setting portion sets the frequency depending on a value of a difference between a detection temperature of the first temperature detecting member and a detection temperature of the second temperature detecting member.