Acoustic Sensor Counter Electrode Perforation Design
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Solution Overview
Problem
Conventional acoustic sensors face challenges in inspecting the gap and vibration characteristics of the vibrating electrode plate due to small acoustic perforations, leading to reduced sensitivity and sticking issues, as well as air damping, which hampers accurate measurement and functionality.
Innovation Solution
The acoustic sensor incorporates a counter electrode plate with a larger opening area acoustic perforation in the central region of the vibrating electrode plate, allowing for precise measurement and reducing sticking and air damping by enhancing water evaporation and minimizing electrostatic forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If acoustic perforations with small uniform opening areas are provided in the counter electrode plate, then the sensitivity of the acoustic sensor is maintained, but the inspection of the vibrating electrode plate becomes difficult
Solution Approach 1:
The patent applies local quality by providing acoustic perforations with different opening areas at different locations on the counter electrode plate. Specifically, a first acoustic perforation with a larger opening area is provided at a first location for inspection purposes, while second acoustic perforations with smaller opening areas are provided at second locations for maintaining sensor sensitivity. This allows the counter electrode plate to have different local properties optimized for different functions.
2Measurement precision
If the opening area of acoustic perforations is increased to enable inspection, then the inspection capability is improved, but air damping of the vibrating electrode plate increases
Solution Approach 1:
The patent resolves this contradiction by implementing local quality through spatially differentiated acoustic perforations. The first acoustic perforation with larger opening area is strategically placed at a first location where inspection is needed, while multiple second acoustic perforations with smaller opening areas are placed at second locations to minimize air damping. This localized approach allows large openings for inspection without subjecting the entire vibrating electrode plate to increased air damping.
Solution Approach 2:
The patent applies segmentation by dividing the acoustic perforations into two distinct groups: first acoustic perforations with larger opening areas for inspection, and second acoustic perforations with smaller opening areas for maintaining sensor performance. This segmentation allows each group to fulfill its specific function without compromising the other, as the smaller perforations are distributed to maintain overall sensitivity while the larger perforation provides inspection access.
3Ease of operation
If acoustic perforations are provided in the counter electrode plate, then sound pressure can pass through to vibrate the vibrating electrode plate, but electrostatic attraction causes the vibrating electrode plate to stick to the counter electrode plate
Solution Approach 1:
The patent applies local quality by providing acoustic perforations with different opening areas at different locations. The larger first acoustic perforation facilitates sound pressure transmission and inspection, while the distributed smaller second acoustic perforations reduce the overall electrode area of the counter electrode plate, thereby reducing electrostatic attraction and preventing sticking.
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
This design enables accurate measurement of vibration characteristics with improved sensitivity and reduced sticking and air damping, maintaining the sensor's performance while allowing for effective inspection and operation.
Implementation Method 1
when a sound pressure (acoustic vibration) reaches the vibrating electrode plate 12 through the acoustic perforations 14 in the counter electrode plate 13, the vibrating electrode plate 12 vibrates microscopically in response to the vibration
Implementation Method 2
the acoustic vibration is detected by detecting a change in electrostatic capacitance between the vibrating electrode plate 12 and the counter electrode plate 13
Implementation Method 3
Air in the micro gap is released through the acoustic perforation, thereby preventing air damping of the vibrating electrode plate
Data Source
AI summary
A vibrating electrode plate 24 that senses a sound pressure faces a counter electrode plate 25 to form a capacitance type acoustic sensor. Acoustic perforations are opened in the counter electrode plate 25 in order to allow vibration to pass through. The acoustic perforations opened in the counter electrode plate 25 include plural acoustic perforations 31 having a relatively small opening area and one acoustic perforation 36 having a relatively large opening area. The acoustic perforations 31 and 36 are disposed into a lattice shape at equal intervals. Assuming that L is a width of a diaphragm 28, in the counter electrode plate 25, the acoustic perforation 36 having the large opening area is provided within a circular region a having a radius r=L/4 around a position facing a center of the diaphragm 28.