Directional Microphone Cover Member Pressure Gradient
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Solution Overview
Problem
Existing directional microphones lack sufficient sensitivity due to inadequate pressure gradients between the upper and lower portions of the resonator array, limiting their ability to effectively capture acoustic signals.
Innovation Solution
Incorporating a cover member and/or fixing member that increases the pressure gradient by covering the open portions of the cavity not covered by the resonator array, either as a thin film or with a thickness similar to the resonators, to enhance the displacement and sensitivity of the microphone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a resonator array is arranged over a cavity in a substrate, then directional sensitivity is improved, but the pressure gradient between upper and lower portions remains insufficient
Solution Approach 1:
A cover member is introduced as an intermediary element that covers the open portion of the cavity. This cover member acts as a mediator to enhance the pressure gradient between the upper and lower portions of the resonator array, thereby improving directional sensitivity without requiring fundamental changes to the resonator structure itself.
Solution Approach 2:
The invention changes the physical parameters of the cavity system by introducing a cover member with specific thickness characteristics (comparable to or greater than resonator height). This parameter change transforms the pressure distribution characteristics within the cavity, creating a stronger pressure gradient that enhances the microphone's directional sensitivity.
2Ease of manufacture
If the cavity is left open, then manufacturing is simpler, but sensitivity is reduced due to inadequate pressure gradient
Solution Approach 1:
Instead of closing the entire cavity or making fundamental manufacturing changes, the invention applies a localized solution by placing a cover member only over the open portion of the cavity. This local modification is sufficient to enhance the pressure gradient and sensitivity while maintaining the overall simplicity of the manufacturing process.
3Measurement precision
If resonators are arranged to cover part of the cavity, then directional characteristics are achieved, but the uncovered portions reduce pressure gradient effectiveness
Solution Approach 1:
The cover member serves multiple functions simultaneously: it covers the open portions of the cavity to enhance pressure gradient, it supports the resonator array structure, and it contributes to the overall acoustic performance. This multi-functionality resolves the contradiction by making the cover structure serve both structural and acoustic enhancement purposes.
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 increased pressure gradient results in improved sensitivity and directionality of the microphone, demonstrated by enhanced displacement and frequency response characteristics, increasing sensitivity by up to 6.5 dB compared to conventional designs.
Implementation Method 1
a resonator array and a cover member. The resonator array may include a plurality of resonators having different center frequencies and arranged above the cavity
Implementation Method 2
the cover member is provided to cover an open portion in the cavity not covered by the resonator array. The cover member may increase a pressure gradient between an upper portion and a lower portion of the resonator array
Data Source
Figure 1
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Figure 4~5
AI summary
A directional microphone is provided which includes a substrate having a cavity that penetrates therethrough, a resonator array of at least one resonator, and a cover member. Each of the resonator array and the cover member covers covering at least a part of the cavity.