Capacitance Sensor Segmented Electrodes Dynamic Range
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Solution Overview
Problem
Conventional microphones face challenges in achieving a wide dynamic range due to trade-offs between sensitivity and total harmonic distortion, with acoustic sensors having different detection sensitivities exhibiting characteristic variations and mismatch issues when formed over different chips or on the same chip, leading to limited detection sound pressure range and compromised sound quality.
Innovation Solution
A capacitance type sensor with a substrate, vibration electrode plate, back plate, and fixed electrode plate, where at least one of the electrode plates is separated into regions to form sensing sections with varying sensitivities, and a barrier electrode is used to prevent signal interference and leak signals, reducing harmonic distortion and characteristic mismatch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensitivity of the acoustic sensor is increased to detect low sound pressure, then the detection sensitivity is improved, but the total harmonic distortion increases when detecting high sound pressure
Solution Approach 1:
The acoustic sensor is divided into multiple sensing sections with different sensitivities (first sensing section with high sensitivity for low sound pressure, second sensing section with low sensitivity for high sound pressure). Each section independently processes different sound pressure ranges, allowing the system to maintain low harmonic distortion across the entire dynamic range while preserving detection sensitivity for both low and high sound pressures.
2Adaptability or versatility
If multiple acoustic sensors with different sensitivities are used to widen the dynamic range, then the detection range is improved, but the acoustic characteristic variation and mismatch between sensors increases
Solution Approach 1:
Multiple sensing sections with different sensitivities are integrated into a single acoustic sensor chip rather than using separate sensors. This integration ensures that all sensing sections share the same acoustic environment and mechanical structure, eliminating acoustic characteristic variation and mismatch between sensors while maintaining a wide dynamic range through the combination of different sensitivity sections.
Solution Approach 2:
Different regions of the sensing section are designed with locally optimized characteristics (different electrode plate areas, different gap distances) to create sections with different sensitivities. This allows each local region to be tailored for specific sound pressure ranges while maintaining acoustic consistency across the entire sensor structure.
3Measurement precision
If the output signal amplitude is increased to improve sensitivity, then the detection capability is improved, but the harmonic distortion in the output signal increases
Solution Approach 1:
The output signal is segmented from different sensing sections with different sensitivities. The high-sensitivity section provides strong output for low sound pressure without excessive amplitude that would cause distortion, while the low-sensitivity section provides appropriate amplitude for high sound pressure. This segmentation allows the system to maintain optimal output signal characteristics across the entire dynamic range.
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 enables a wide dynamic range without lowering sensitivity, reduces characteristic variation and frequency mismatch between sensing sections, and prevents sensitivity changes due to leak signals, thereby improving sound quality and extending the maximum detection sound pressure range.
Implementation Method 1
a capacitance type sensor which uses a capacitor structure including a vibration electrode plate (diaphragm) and a fixed electrode plate
Implementation Method 2
a capacitance type sensor of very small size manufactured by using MEMS (Micro Electro Mechanical System) technique
Data Source
AI summary
A capacitance type sensor has a substrate, a vibration electrode plate formed over the substrate, a back plate formed over the substrate so as to cover the vibration electrode plate, and a fixed electrode plate provided on the back plate so as to be opposite to the vibration electrode plate. At least one of the vibration electrode plate and the fixed electrode plate is separated into a plurality of regions, each of the plurality of regions being formed with a sensing section including the vibration electrode plate and the fixed electrode plate. A barrier electrode is provided between respective sensing sections of at least one adjacent pair of regions of the plurality of regions to prevent signal interference between the respective sensing sections.