Capacitance Transducer Stoppers for Acoustic Sensing
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Solution Overview
Problem
Conventional microphones face a trade-off between sticking resistance and damage resistance, making it difficult to maintain both high sensitivity and durability, especially when detecting a wide range of sound pressures from low to high volumes.
Innovation Solution
A capacitance-type transducer with multiple sensing portions, featuring stoppers of varying projection lengths and surface areas, where shorter stoppers provide higher sticking resistance in large surface area regions and longer stoppers offer improved damage resistance in smaller surface area regions, thereby preventing sticking and damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If uniform stoppers with the same projection length are provided on the back plate, then sticking prevention is achieved, but damage resistance is compromised for small surface area diaphragms
Solution Approach 1:
The patent applies local quality by providing stoppers with different projection lengths corresponding to different diaphragm surface areas. Specifically, stoppers in regions with smaller diaphragm surface areas have longer projection lengths to prevent excessive bending and damage, while stoppers in regions with larger diaphragm surface areas have shorter projection lengths to allow sufficient deformation for acoustic sensing. This localized differentiation resolves the contradiction between sticking prevention and damage resistance.
Solution Approach 2:
The back plate is segmented into multiple regions with different stopper projection lengths based on the diaphragm surface area characteristics of each region. The stoppers are divided into first stoppers (shorter projection length) for large surface area regions and second stoppers (longer projection length) for small surface area regions. This segmentation allows each region to have optimized stopper characteristics, simultaneously achieving sticking resistance and damage resistance.
2Measurement precision
If the diaphragm surface area is increased to improve acoustic vibration detection sensitivity, then low-volume sound detection is enhanced, but the risk of sticking increases
Solution Approach 1:
The patent applies local quality by differentiating stopper projection lengths according to diaphragm surface area regions. In regions with larger diaphragm surface areas where sticking risk is higher, shorter stoppers are provided to allow greater deformation range. In regions with smaller diaphragm surface areas, longer stoppers prevent excessive bending. This localized approach enables the diaphragm to have sufficient surface area for high sensitivity while maintaining sticking resistance through region-specific stopper design.
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 enhances both sticking resistance and damage resistance, allowing the transducer to effectively detect a wide range of sound pressures without sticking or damage, thus improving overall performance.
Implementation Method 1
capacitance-type transducer constituted by a capacitor structure made up of movable electrodes (diaphragm) and fixed electrodes
Data Source
AI summary
A capacitance-type transducer has a back plate having a fixed electrode, a diaphragm that opposes the back plate via an air gap and serves as a movable electrode, and at least first stoppers having a first projection length and second stoppers having a second projection length that project from at least one of a surface of the back plate on the air gap side and a surface of the diaphragm on the air gap side. At least one of the diaphragm and the fixed electrode is divided into at least a first region having a first surface area and a second region having a second surface area, a first sensing portion made up of the diaphragm and the fixed electrode is constituted in the first region, and a second sensing portion made up of the diaphragm and the fixed electrode is constituted in the second region.