Capacitive Microphone Diaphragm Segmentation for Dynamic Range
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Solution Overview
Problem
Conventional microphones with multiple acoustic sensors suffer from acoustic characteristic variation and mismatching due to independent capacitor structures, limiting their dynamic range and sensitivity, especially when detecting low- and high-volume sounds simultaneously.
Innovation Solution
A capacitive sensor design with a vibrating electrode plate divided into regions forming multiple sensing portions, each with different sensitivities, integrated on a single substrate to reduce variation and mismatching, allowing for a wide dynamic range and noise reduction by dividing the vibrating electrode plate into regions with varying areas or displacements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple independent acoustic sensors are used to detect a wide sound pressure range, then the dynamic range is improved, but acoustic characteristic variation and mismatching occur between sensors
Solution Approach 1:
The patent merges multiple sensing portions into a single integrated capacitor structure where the vibrating electrode plate is divided into multiple regions that form first and second sensing portions. This integration ensures that all sensing portions share common structural characteristics, eliminating variation and mismatching while maintaining the ability to detect a wide sound pressure range through combined sensing regions of different areas.
Solution Approach 2:
The vibrating electrode plate is segmented into multiple regions corresponding to first and second sensing portions with different areas. This segmentation allows each portion to be optimized for different sound pressure levels while remaining part of a unified structure, thus achieving wide dynamic range without characteristic variation.
2Measurement precision
If the vibrating electrode plate area is increased to improve sensitivity for low-volume sounds, then detection sensitivity is improved, but harmonic distortion increases for high-volume sounds
Solution Approach 1:
Different regions of the vibrating electrode plate are given different areas to create local quality variations. The first sensing portion has a larger area for high sensitivity to low-volume sounds, while the second sensing portion has a smaller area to handle high-volume sounds without excessive distortion. Each region is optimized for its specific function while being part of the same plate.
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 integrated design enhances the microphone's ability to detect a wide range of sound pressures without sacrificing sensitivity, reduces harmonic distortion, and minimizes noise, thereby expanding the dynamic range and maintaining high sound quality across varying sound pressures.
Implementation Method 1
a capacitive sensor constituted by a capacitor structure that is made up of a vibrating electrode plate (diaphragm) and a fixed electrode plate
Data Source
AI summary
A chamber that penetrates vertically is formed in a silicon substrate. A diaphragm is arranged on the upper surface of the silicon substrate so as to cover the upper opening of the chamber. The diaphragm is divided by slits into a region located above the chamber (first diaphragm) and a region located above the upper surface of the silicon substrate (second diaphragm). A fixed electrode plate is arranged above the first diaphragm, and a low-volume first acoustic sensing portion is formed by the first diaphragm and the fixed electrode plate. Also, a high-volume second acoustic sensing portion is formed by the second diaphragm and the upper surface (electrically conducting layer) of the silicon substrate.