Microwave Frequency Control for Uniform Heating
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Solution Overview
Problem
Microwave ovens face challenges in achieving uniform heating due to non-uniform energy dissipation patterns, resulting in hot and cold spots within the cavity, which existing methods have not adequately addressed.
Innovation Solution
The method involves irradiating a load with a spectrum of frequencies by varying the duration of energy transmission at each frequency, using a controller to adjust the power and time of each frequency based on measured dissipation information to achieve a predetermined energy dissipation pattern, allowing for efficient energy transfer and uniform heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If multiple frequencies are used with high power transmission, then energy transfer efficiency is improved, but non-uniform heating and hot spots are generated
Solution Approach 1:
The patent applies periodic action by transmitting different frequencies in alternating time intervals rather than simultaneously. The controller transmits first frequency during first time intervals and second frequency during second time intervals, creating a time-division multiplexed transmission pattern that prevents simultaneous energy concentration at different frequencies while maintaining overall heating efficiency
Solution Approach 2:
The patent implements dynamics by making the transmission system adaptable and adjustable. The controller dynamically selects which frequencies to transmit based on real-time feedback from sensors that monitor temperature distribution and energy absorption characteristics of the load, allowing the system to optimize heating uniformity while maintaining efficiency
2Temperature
If mode stirring and load movement are used to improve uniformity, then heating uniformity is improved, but device complexity and process time increase
Solution Approach 1:
The patent replaces mechanical systems (mode stirrers and load movement mechanisms) with an electromagnetic field-based solution. By using multiple frequencies transmitted in time intervals and controlling energy distribution through frequency selection rather than mechanical agitation, the system achieves heating uniformity without adding mechanical complexity
Solution Approach 2:
The patent changes the electromagnetic parameters (frequency, transmission timing, power levels) to achieve uniform heating. The controller adjusts which frequencies are transmitted and for how long based on load characteristics and real-time feedback, replacing the need for mechanical mode stirring with parameter-based control
3Use of energy by moving object
If frequency selection is based on initial dissipation characteristics, then energy transfer efficiency is improved, but heating uniformity deteriorates as load temperature changes
Solution Approach 1:
The patent implements feedback by using sensors to continuously monitor the load's temperature distribution and energy absorption characteristics during the heating process. The controller receives this feedback and dynamically adjusts the frequency selection and transmission timing to maintain both efficiency and uniformity as the load's dissipation characteristics change with temperature
Solution Approach 2:
The system transitions from static frequency selection (based on initial characteristics) to dynamic frequency selection (based on real-time feedback). The controller adapts the transmission parameters throughout the heating process, selecting different frequencies at different time intervals according to the current state of the load, thereby maintaining effectiveness despite changing dissipation characteristics
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 more uniform energy dissipation across frequencies, reducing the overall process time and maintaining energy transfer efficiency while preventing damage to the load, even at maximal power levels.
Implementation Method 1
dissipation of electromagnetic (EM) energy in a load, and more particularly but not exclusively with RF heating, for example using microwave or UHF energy for thawing, heating and/or cooking
Implementation Method 2
Irradiating is performed by transmitting different amounts of energy at different frequencies... Irradiating the load may be performed in a resonance cavity
Data Source
AI summary
Method of irradiating a load placed in a cavity by radiating UHF or microwave radiation into the cavity. The method includes setting transmission durations, by setting for each of a plurality of frequencies, a respective transmission duration, repeatedly causing energy to be transmitted into the cavity at the plurality of frequencies according to a duty cycle, wherein the duty cycle defines an allotted transmission time for each of the plurality of frequencies, and switching ON or OFF transmission of the energy at certain frequencies, so that over a plurality of repetitions of the duty cycle the energy is transmitted at each of the plurality of frequencies for the respective transmission duration.