Microwave Heating Control via Reflected Power Detection
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Solution Overview
Problem
Conventional microwave heating devices using magnetrons face challenges in adjusting microwave frequencies, leading to non-uniform heating and thermal destruction of semiconductor devices due to reflected electric power, which limits their ability to control heating distribution effectively.
Innovation Solution
A microwave heating device with a microwave generating portion having a variable frequency function, plural feeding portions, and an electric-power detection portion that controls the operation based on detected reflected microwaves to estimate and adjust the heating frequency and power for uniform heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If magnetrons are used as microwave generating means, then microwave heating can be performed, but frequency adjustment is not possible and reflected electric power causes thermal destruction
Solution Approach 1:
The patent changes the operating frequency parameter dynamically by sweeping through a frequency range and selecting the optimal frequency that minimizes reflected electric power. This allows the system to adapt to different heating conditions and prevent thermal destruction of semiconductor devices while maintaining effective heating performance.
Solution Approach 2:
The patent employs feedback by detecting reflected electric power and using this information to adjust the microwave generating means frequency. The control unit continuously monitors reflected power and modifies the operating frequency accordingly, creating a closed-loop control system that prevents thermal destruction while optimizing heating efficiency.
2Measurement precision
If reflected electric power is detected at a single portion, then control can be performed, but heating distribution information cannot be acquired
Solution Approach 1:
The patent divides the detection function into multiple segments by placing detection portions at different locations within the heating chamber. Each detection portion monitors reflected electric power from its local position, enabling the system to acquire spatial distribution information about heating conditions and identify non-uniform heating patterns.
Solution Approach 2:
The patent transitions from single-point detection to multi-point spatial detection, adding the spatial dimension to the measurement. By detecting reflected electric power at multiple locations simultaneously, the system gains insight into the three-dimensional heating distribution pattern, enabling more comprehensive control of heating uniformity.
3Manufacturing precision
If frequency is fixed, then device complexity is reduced, but heating uniformity deteriorates
Solution Approach 1:
The patent transitions from a static fixed-frequency system to a dynamic frequency-adjusting system. The microwave generating means frequency is continuously modified based on real-time detection of reflected electric power, allowing the system to adapt to changing heating conditions and maintain uniform heating throughout the heating process.
Solution Approach 2:
The patent implements periodic frequency sweeping through a predetermined frequency range during heating operations. This periodic frequency adjustment allows the system to minimize reflected electric power at different stages of heating, improving heating uniformity while managing device complexity through systematic frequency variation.
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 device achieves uniform heating of objects by detecting and adjusting microwave frequency and power based on reflected electric power, reducing thermal destruction and enhancing heating control, thereby improving heating reliability and efficiency.
Implementation Method 1
When an object to be heated (a to-be-heated object) is housed within the heating chamber in a microwave heating device and is being subjected to microwave heating processing thereby, the to-be-heated object changes its properties along with the heating processing. Accordingly, microwaves supplied to the heating chamber which houses the to-be-heated object are absorbed by the to-be-heated object
Implementation Method 2
microwaves supplied to the heating chamber which houses the to-be-heated object are absorbed by the to-be-heated object, to varying degrees, which induces a reflection phenomenon that the microwaves are reflected back toward the microwave generating means from the heating chamber
Data Source
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AI summary
In order to provide a microwave heating device and a microwave heating control method which are capable of uniformly heating a to-be-heated object in a desired state, by employing plural feeding portions provided in a heating chamber on the basis of information about reflected electric power from the respective feeding portions; a control portion (21) controls to supply microwave electric power from plural feeding potions (20a, 20b, 20c and 20d) to a heating chamber (100) by operating a microwave generating portion (10) at a heating frequency for heating a to-be-heated object, estimates a heating state for the to-be-heated object on the basis of per-unit-time increase/ decrease change states of detected levels of detection signals detected by electric-power detection portions (18a, 18b, 18c and 18d), and controls the heating frequency and the microwave electric power supplied from the feeding portions to the heating chamber.