Induction Heating Fixing Device with Temperature Feedback Control
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Solution Overview
Problem
The existing fixing devices in image forming apparatuses, such as MFPs, face issues with the IGBT element overheating due to excessive temperature increase during continuous operation or warming-up, which can lead to damage, especially when using electromagnetic induction heating methods.
Innovation Solution
The implementation of a fixing device with a temperature detection section that monitors the auxiliary heat generation section's temperature and adjusts the output of the induced current generation section to prevent overheating, using a magnetic shunt alloy auxiliary heat generation plate and a control system to manage the magnetic flux and reduce the load resistance, thereby protecting the IGBT element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high output electromagnetic induction heating is continued to maintain fixing belt temperature, then heating efficiency is improved, but the IGBT element temperature excessively increases causing damage
Solution Approach 1:
The patent employs a temperature detection section that continuously monitors the temperature of the auxiliary heat generation section and feeds this information back to the control section. The control section adjusts the output of the induced current generation section based on the detected temperature, creating a closed-loop feedback system that prevents IGBT element overheating while maintaining effective fixing belt heating
Solution Approach 2:
The patent changes the operating parameters of the electromagnetic induction heating system by detecting temperature conditions and dynamically adjusting the output power of the IH coil unit. When the auxiliary heat generation plate temperature exceeds a predetermined threshold, the control section reduces the output, thereby changing the heating parameters to prevent IGBT element damage
2Speed
If auxiliary heat generation section increases temperature rapidly during warming-up, then warming-up speed is improved, but IGBT element is damaged due to excessive temperature
Solution Approach 1:
During warming-up operation, the temperature detection section continuously monitors the auxiliary heat generation section temperature and provides feedback to the control section. This feedback mechanism enables the control section to adjust the induction heating output in real-time, allowing rapid warming-up while preventing IGBT element temperature from exceeding safe limits
Solution Approach 2:
The control section periodically checks the temperature detection results during warming-up and adjusts the heating output accordingly. This periodic monitoring and adjustment enables the system to maintain high warming-up speed while periodically preventing excessive temperature buildup that would damage the IGBT element
3Reliability
If temperature detection and output reduction control are implemented, then IGBT element protection is improved, but device complexity increases
Solution Approach 1:
The patent implements a feedback control system where the temperature detection section monitors the auxiliary heat generation section and the control section adjusts the induced current generation section output accordingly. This feedback mechanism provides effective IGBT element protection through relatively simple additions of temperature sensing and control logic
Solution Approach 2:
The control section acts as an intermediary between the temperature detection section and the induced current generation section. It receives temperature information, processes it according to predetermined criteria, and adjusts the heating output accordingly, providing protection without requiring complex direct intervention in the heating mechanism
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 solution effectively prevents IGBT element damage by reducing the output from the IH coil unit when the auxiliary heat generation plate's temperature exceeds a certain threshold, maintaining the fixing belt at optimal temperatures and ensuring continuous operation without overheating.
Implementation Method 1
The induced current generation section generates magnetic flux when a high frequency current is applied thereto from an inverter driving circuit
Implementation Method 2
The image forming apparatus heats a conductive layer of a fixing belt by using an electromagnetic induction heating method
Implementation Method 3
The auxiliary heat generation section concentrates magnetic flux during electromagnetic induction heating so as to increase an amount of generated heat in the fixing belt
Implementation Method 4
The temperature detection section detects a temperature of the auxiliary heat generation section
Implementation Method 5
The control section reduces an output from the induced current generation section on the basis of a detection result from the temperature detection section
Data Source
AI summary
A fixing device of an exemplary embodiment includes a fixing belt, an induced current generation section, an auxiliary heat generation section, a temperature detection section, and a control section. The fixing belt includes a conductive layer. The induced current generation section opposes the fixing belt in a thickness direction. The induced current generation section performs electromagnetic induction heating on the conductive layer. The auxiliary heat generation section opposes the induced current generation section with the fixing belt interposed therebetween. The temperature detection section detects a temperature of the auxiliary heat generation section. The control section reduces an output from the induced current generation section on the basis of a detection result from the temperature detection section.