Capacitive Sound Transducer Attenuation Disk Offset Perforations
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Solution Overview
Problem
Capacitive sound transducers in condenser microphones suffer from nonlinear distortions and unwanted partial oscillations due to air gap viscosity and mechanical resonance, leading to non-linear sound signal reproduction and frequency-dependent transmission characteristics.
Innovation Solution
A sound-permeable attenuation disk with offset perforations is introduced between the diaphragm and the counterelectrode, exploiting air viscosity for localized attenuation of partial oscillations, maintaining minimal impact on other acoustic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If air gap attenuation is increased to reduce nonlinearity, then nonlinearity is reduced, but transducer sensitivity is reduced
Solution Approach 1:
The counterelectrode is segmented into multiple regions with different perforation patterns. Specific regions have higher perforation density to provide localized attenuation where diaphragm oscillations occur, while other regions maintain lower perforation density to preserve overall sensitivity. This spatial segmentation allows simultaneous achievement of linearity and sensitivity.
Solution Approach 2:
Different regions of the counterelectrode are assigned different local properties (perforation densities) based on the local oscillation characteristics of the diaphragm. Regions prone to high-frequency oscillations receive higher attenuation, while other regions maintain lower attenuation to preserve sensitivity. This local quality approach resolves the global contradiction between linearity and sensitivity.
2Stability of the object's composition
If the distance between diaphragm and counterelectrode is decreased to suppress oscillations, then oscillations are suppressed, but transducer sensitivity is reduced
Solution Approach 1:
The counterelectrode surface is segmented into regions with different perforation characteristics. Regions where diaphragm oscillations occur are provided with higher perforation density to increase local attenuation, while other regions have lower perforation density to maintain sensitivity. This allows oscillation suppression without overall sensitivity loss.
Solution Approach 2:
The counterelectrode is designed with spatially varying local properties (perforation density) matched to the local oscillation modes of the diaphragm. High-perforation regions are placed where oscillations occur, providing localized damping without reducing the overall air gap distance and thus preserving sensitivity in non-oscillating regions.
3Productivity
If perforated regions of counterelectrode and attenuation disk overlap, then sound permeability is improved, but attenuation effectiveness is reduced
Solution Approach 1:
The attenuation disk is designed with asymmetric perforation patterns relative to the counterelectrode. The perforations are deliberately offset and non-coincident, creating an asymmetric arrangement where most regions experience both perforations (good sound permeability) while specific regions have overlapping or adjacent perforations that provide localized attenuation where oscillations occur.
Solution Approach 2:
The solution moves from a one-dimensional consideration (simple overlap or no overlap) to a two-dimensional spatial arrangement. By carefully designing the pattern, size, and distribution of perforations in both the counterelectrode and attenuation disk, the system achieves both sound permeability and attenuation effectiveness through sophisticated spatial configuration rather than simple binary overlap.
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 effectively suppresses natural oscillations and distortions, improving high-frequency transmission quality and maintaining transducer sensitivity, with a simple and cost-efficient constructional modification.
Implementation Method 1
exploiting air viscosity for localized attenuation of partial oscillations
Implementation Method 2
The diaphragm and counterelectrode are designed to be electrically conductive and form an electrical capacitor whose capacitance is dependent on the diaphragm deflection caused by the sound
Data Source
AI summary
A capacitive sound transducer provided with a perforated attenuation disk. The invention further relates to a capacitive sound transducer and a condenser microphone having such a sound transducer. The sound transducer comprises a diaphragm and a counterelectrode which is disposed at a short distance from the diaphragm and provided with first perforations. In order to attenuate natural oscillations of the diaphragm at high frequencies, a capacitive sound transducer is proposed in which a sound-permeable attenuation disk provided with second perforations is disposed at a short distance from the diaphragm and opposite the counterelectrode. In this arrangement, the first perforations and the second perforations are also offset in relation to each other.