Induction Fixing Temperature Prediction for Switching Element Protection
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Solution Overview
Problem
In image forming apparatuses using electromagnetic induction heating, the switching element's temperature can rise excessively, leading to deterioration or damage, while reducing the current to prevent this can result in insufficient heat for fixing, causing defective fixing due to temperature fluctuations.
Innovation Solution
An image forming apparatus with a detection unit for the fixing member's temperature, a calculation unit for temperature change, and a prediction unit to forecast the switching element's temperature, allowing controlled power supply adjustments to maintain necessary fixing temperatures by restricting switching when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the duty ratio is raised to maintain fixing member temperature when temperature drops or voltage drops, then the fixing member temperature is maintained, but the switching element temperature rises excessively causing deterioration or damage
Solution Approach 1:
The system performs preliminary cooling action by reducing the duty ratio before the switching element temperature becomes excessively high. The temperature detection unit detects switching element temperature, and when it exceeds a predetermined threshold, the control unit proactively reduces the duty ratio to prevent damage, rather than waiting for failure to occur.
Solution Approach 2:
The system implements feedback control by continuously detecting the switching element temperature with the temperature detection unit and adjusting the duty ratio based on this feedback. When the detected temperature is at or below the threshold, normal duty ratio is maintained; when it exceeds the threshold, the duty ratio is reduced to cool the switching element, creating a closed-loop control system.
2Reliability
If the current supplied to the switching element is reduced when temperature exceeds predetermined value, then the switching element temperature is controlled, but the fixing member temperature drops below necessary level causing defective fixing
Solution Approach 1:
The system dynamically adjusts the duty ratio based on real-time switching element temperature conditions. The control unit changes the duty ratio from normal to reduced level according to the detected temperature state, making the system adaptive rather than static. This dynamic adjustment allows the system to respond to changing thermal conditions and maintain both switching element safety and fixing member temperature.
Solution Approach 2:
The system performs preliminary cooling action by reducing the duty ratio before the switching element temperature becomes excessively high. The temperature detection unit detects switching element temperature, and when it exceeds a predetermined threshold, the control unit proactively reduces the duty ratio to prevent damage, rather than waiting for failure to occur.
3Reliability
If the duty ratio is maintained at reduced level until switching element temperature falls to predetermined value, then the switching element is protected, but the fixing member temperature remains insufficient for proper fixing
Solution Approach 1:
The system performs preliminary cooling action by reducing the duty ratio before the switching element temperature becomes excessively high. The temperature detection unit detects switching element temperature, and when it exceeds a predetermined threshold, the control unit proactively reduces the duty ratio to prevent damage, rather than waiting for failure to occur.
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
Prevents excessive temperature rise in the switching element while ensuring the fixing member reaches the required temperature for image fixation, enhancing fixing quality and preventing damage.
Implementation Method 1
an excitation coil is caused to produce magnetic flux by switching the current flowing to the excitation coil via a switching element. The magnetic flux then causes the electromagnetic induction heating layer to heat up
Implementation Method 2
a fixing member, such as a fixing roller and a fixing belt, is provided with an electromagnetic induction heating layer. An excitation coil is caused to produce magnetic flux by switching the current flowing to the excitation coil via a switching element. The magnetic flux then causes the electromagnetic induction heating layer to heat up
Data Source
AI summary
An image forming apparatus uses a switching element to switch current flowing to an excitation coil, so that a heating layer in a fixing member produces heat that fixes an image to a transported sheet. Based on a change in temperature of the switching element over time, a prediction unit determines, at a predetermined first time point, a predicted temperature of the switching element at a second time point at which a tip of the sheet is scheduled to arrive at the fixing member. When the predicted temperature is at least a predetermined value, a control unit controls power supplied to the excitation coil by restricting switching of the switching element and lifting the restriction, so that by the second time point the detected temperature of the fixing member reaches a temperature necessary for fixing.