Microwave Door Grid with Rounded Corners
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Solution Overview
Problem
Existing microwave oven doors face challenges in effectively preventing microwave radiation leakage through viewing openings while maintaining good optical visibility and minimizing microwave losses.
Innovation Solution
A perforated electrically conductive grid with micro-holes arranged in a regular pattern, particularly with rectangular shapes and rounded corners, is used to cover the viewing opening, optimizing microwave attenuation and reducing current density peaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a perforated metal grid with sharp-cornered holes is used to cover the viewing opening, then microwave shielding is achieved, but microwave losses increase due to high current density at sharp corners
Solution Approach 1:
The patent applies curvature by replacing sharp-cornered square holes with rounded-corner holes in the metal grid. This geometric modification reduces the concentration of electrical current at corner points, thereby decreasing microwave energy losses while maintaining the shielding function. The rounded corners distribute current more evenly across the grid structure, improving both efficiency and reliability.
2Illumination intensity
If the grid holes are made larger to improve optical visibility, then transparency increases, but microwave shielding efficiency decreases
Solution Approach 1:
The patent optimizes multiple parameters simultaneously: hole size, hole shape (rounded corners), hole pitch, and metal strip width. By carefully selecting these parameters, the grid achieves a balance where holes are large enough for good visibility but small and shaped in a way that maintains microwave shielding. The rounded corners specifically allow slightly larger hole areas while preventing current concentration that would compromise shielding.
3Reliability
If the metal grid thickness is increased to improve shielding, then microwave attenuation improves, but optical transparency decreases and manufacturing complexity increases
Solution Approach 1:
The patent optimizes the thickness parameter of the metal grid to find the optimal balance point. The rounded-corner hole design allows effective shielding with thinner metal sections compared to sharp-cornered designs, as the curved geometry reduces current concentration and improves current distribution. This enables adequate shielding performance with reduced metal thickness, thereby maintaining better optical transparency.
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 solution provides high microwave shielding efficiency with low losses and good optical transparency, enhancing the reliability and longevity of the microwave-tight shield.
Implementation Method 1
at least one perforated electrically conductive grid which covers a viewing opening of the door... prevention of microwave radiation from escaping from the viewing opening
Implementation Method 2
the rounded corners reduce the electrical current density induced by microwaves there compared to a pointed or sharp corner, thereby reducing microwave losses
Data Source
Figure 1~2
AI summary
The invention relates to a door (1) for a household microwave appliance (G), having at least one perforated, electrically conductive lattice (4), in particular a metal lattice, which covers a viewing opening of the door (1) and has a plurality of micro-holes (5), arranged in a regular pattern, wherein the micro-holes (5) have a rectangular, in particular a square basic shape having rounded corners. The invention is in particular advantageously applicable to independent household microwave appliances and ovens having microwave functions.