Induction Heating Coil Voltage Control for Noise Reduction
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Solution Overview
Problem
Existing image forming apparatuses using induction heating for fixing devices face interference noise due to differing power supply timings to multiple coils, leading to longer times to reach fixing temperature when power distribution is maintained to inhibit noise.
Innovation Solution
A fixing device with multiple coils for induction heating, where a driving signal transmission unit synchronizes the operation of switching elements connected to each coil, and a voltage drop unit adjusts input voltages to ensure continuous power supply without generating interference noise, by operating the coils at the same timing with different input voltages and controlling voltage drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the timing of supplying electric power to multiple coils is switched to inhibit interference sound, then interference sound is reduced, but the heating efficiency decreases and the time to reach fixing temperature becomes longer
Solution Approach 1:
The patent changes the voltage parameter supplied to each coil individually while maintaining synchronized timing. By adjusting voltage distribution (e.g., V1 and V2 at different levels) rather than switching timing, the system eliminates interference sound and achieves uniform heating without extending the heating cycle.
2Temperature
If different electric powers are supplied to multiple coils to account for temperature differences in the longitudinal direction, then heating uniformity improves, but interference sound is generated due to different operation frequencies
Solution Approach 1:
The patent segments the power supply control by providing different voltages to different coils (e.g., first coil receives V1, second coil receives V2) while maintaining synchronized timing through a common clock signal. This segmentation approach allows independent power adjustment for each coil to achieve uniform temperature distribution without generating interference sound.
Solution Approach 2:
The patent changes the voltage parameter for each coil individually while maintaining the same operation frequency and timing. By adjusting voltage distribution rather than frequency or timing, the system achieves both heating uniformity and noise elimination.
3Object-generated harmful factors
If the same timing is used for multiple coils to eliminate interference sound, then interference sound is inhibited, but power distribution becomes insufficient for optimal heating efficiency
Solution Approach 1:
The patent changes the voltage parameter for each coil individually while maintaining synchronized timing. By adjusting voltage distribution (e.g., different voltage levels V1 and V2 for different coils), the system achieves both interference sound elimination and optimized heating power distribution for maximum heating efficiency.
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 allows for continuous electric power supply to heating coils without generating interference noise, reducing the time to reach the fixing temperature.
Implementation Method 1
a first coil for induction heating that heats the heating body by an induction heating method; a second coil for induction heating that heats the heating body by the induction heating method
Implementation Method 2
heats the heating body by an induction heating method using plural coils for induction heating
Data Source
AI summary
A fixing device includes a heating body; first and second coils for induction heating that heat the heating body by an induction heating method; a first switching element connected to the first coil for induction heating; a second switching element connected to the second coil for induction heating; a driving signal transmission unit that sends a first drive signal to the first switching element and a second drive signal to the second switching element so that the first switching element and the second switching element operate at the same timing to apply a first input voltage to the first coil for induction heating and a second input voltage to the second coil for induction heating; and a voltage drop unit that steps down the first input voltage applied to the first coil for induction heating so that the first input voltage is lower than the second input voltage.