Capacitive Microphone Electrode Protection via Dimensional Shift
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Solution Overview
Problem
Capacitive microphone capsules face challenges in protecting sensitive components, such as the air gap and electrode insulation, from contamination and environmental influences while maintaining sound transmission, leading to potential interference and acoustic losses.
Innovation Solution
A capacitive pickup converter design featuring membrane supports with protruding sides and protective elements with sound-permeable but dirt-impermeable openings, ensuring a distance between the electrode and protective elements, which are electrically conductive and connected to the active membrane, providing enhanced protection without significant acoustic loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fleece is attached directly to the outside of the electrodes to protect the air gap, then protection against contamination is improved, but acoustic losses increase significantly
Solution Approach 1:
The protective fleece is relocated from the front side (acoustic path) to the rear side of the electrode, utilizing the third dimension (depth) to resolve the contradiction. This allows the fleece to protect the electrode without interfering with sound transmission through the front openings.
Solution Approach 2:
The membrane carrier serves as an intermediary structure that holds the protective fleece on its rear side, mediating between the need for protection and the need for acoustic transmission. The carrier positions the fleece at a distance from the electrode, allowing both protection and sound passage.
2Device complexity
If the membrane carrier and electrode lie in one plane, then device complexity is reduced, but protection of the air gap from contamination is insufficient
Solution Approach 1:
The membrane carrier is designed to protrude beyond the electrode in the depth dimension, creating a stepped structure. This dimensional change provides a rear surface on the carrier for mounting the protective fleece, enabling protection without significant structural complexity.
3Reliability
If the electrode is made fully solid for better insulation, then electrical insulation is improved, but sound transmission is blocked
Solution Approach 1:
The electrode is designed with local quality variation: it has sound-permeable openings in the acoustic path area for sound transmission, while the rear side (where the fleece is mounted) provides electrical insulation. This localized differentiation resolves the contradiction between insulation and sound transmission.
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 design effectively shields sensitive areas from contamination and environmental factors while minimizing acoustic losses, ensuring robustness and maintaining the original transmission behavior of the capacitive pickup converter.
Implementation Method 1
The protective element can have at least one opening which is designed in such a way that it is permeable to sound but impermeable to dirt
Implementation Method 2
capacitive pickup converter and a corresponding microphone... a microphone capsule with a capacitive pick-up transducer
Data Source
Figure 1a~1c
Figure 2
AI summary
The invention relates to a capacitive electroacoustic transducer comprising an active membrane (20) and a first and second membrane carrier (60). The active membrane (20) is accommodated between the first and second membrane carriers (60). The first and second membrane carriers (60) each have a flat electrode (30). The membrane carrier and electrode are connected to one another such that the membrane carrier extends past the electrode by a predetermined amount.