Microwave Chamber Reflection Control for Selective Local Heating
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Solution Overview
Problem
Conventional microwave ovens have limited local heating performance, unable to achieve an energy concentration ratio greater than 2:1 for heating two articles with different initial temperatures, leading to uneven heating of food items like hamburg steak and fresh vegetables.
Innovation Solution
The microwave heating device incorporates a reflection angle control device that adjusts the reflection angle of microwaves within the heating chamber, using conductive patches and dielectric layers to control standing wave distribution, allowing for improved local heating performance by directing energy more effectively towards specific areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If an antenna with high microwave radiation directivity is used to concentrate energy on a particular article of food, then local heating performance is improved, but the energy concentration ratio is limited to at most 2:1, which is insufficient for heating articles with different initial temperatures
Solution Approach 1:
The patent applies local quality by creating regions with different reflection characteristics within the heating chamber. By providing reflection control units with different reflection rates at different positions, the system generates localized areas with enhanced energy concentration. This allows the energy concentration ratio to exceed the 2:1 limitation of conventional uniform reflection surfaces, enabling selective heating of specific articles with different thermal requirements.
Solution Approach 2:
The patent changes the reflection rate parameter of the chamber walls by incorporating reflection control units with varying reflection characteristics. This parameter modification allows dynamic control of microwave energy distribution, enabling the system to achieve energy concentration ratios greater than 2:1 for local heating while maintaining overall heating effectiveness.
2Reliability
If the heating chamber is covered with metal to contain microwaves, then microwave safety is improved, but standing waves are generated causing uneven heating of food
Solution Approach 1:
The patent maintains the metal covering for microwave containment but introduces local variations in reflection characteristics through reflection control units. These units create localized differences in microwave reflection rates, which disrupt the formation of uniform standing wave patterns while preserving the overall containment function. This results in reduced heating unevenness without compromising safety.
Solution Approach 2:
The patent converts the harmful effect of uniform standing waves into a benefit by deliberately creating non-uniform reflection patterns. The reflection control units transform the regular standing wave distribution into a more randomized energy distribution, which actually improves heating uniformity while maintaining the metal containment structure for safety.
3Device complexity
If conventional reflection surfaces are used in the heating chamber, then device simplicity is maintained, but standing wave distribution cannot be controlled leading to limited local heating performance
Solution Approach 1:
The patent segments the reflection surface into multiple reflection control units with different reflection rates. This segmentation allows control of standing wave distribution without requiring a completely complex system. Each unit can be independently designed with simple geometric features that modify reflection characteristics, maintaining overall device simplicity while achieving improved local heating precision.
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 configuration enables more precise control over standing wave distribution, allowing for a higher energy concentration ratio, such as 3:1, which effectively heats the hamburg steak while minimizing the temperature increase of the fresh vegetable, thereby enhancing local heating performance.
Implementation Method 1
a reflection angle control device that controls a reflection angle of the microwave
Implementation Method 2
configured to radiate microwaves toward a heating target to dielectrically heat the heating target
Data Source
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AI summary
There are provided heating chamber (103), and reflection angle control device (118) provided on upper wall (108) configuring at least part of walls of heating chamber (103) and configured to control a reflection angle of a microwave to control standing wave distribution in heating chamber (103). Reflection angle control device (118) controls the reflection angle of the microwave when the microwave radiated from microwave radiation device (104) is not directly absorbed into heating target (102) but is reflected by the wall. Standing wave distribution in heating chamber (103) can thus be controlled to be different from ordinary distribution for improvement in local heating performance.