Capacitive Microphone Backplate Insulation for Leakage Prevention
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Solution Overview
Problem
Capacitive microphones are susceptible to current leaks due to moisture, residues, and particles that can cause insulation failures between the backplate and membrane electrodes, leading to increased noise, reduced sensitivity, and higher current consumption, despite existing insulating layers on the backplate facing the membrane.
Innovation Solution
The conductive sections of the backplate are fully or partially encapsulated with insulating material on all vulnerable surfaces, including the top and bottom surfaces and sidewalls of perforation holes, to prevent current leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an insulating layer is placed on the backplate facing the membrane, then current leaks from this face are prevented, but current leaks from the opposite face and side walls of perforation holes cannot be prevented
Solution Approach 1:
The patent applies nested insulation by placing a first insulating layer on the first face of the backplate and a second insulating layer on the second face of the backplate, with the second layer nested within the structural confines of the first. This nested arrangement ensures that both faces and the side walls of perforation holes are covered, preventing current leaks from any surface without requiring a single complex insulation structure.
Solution Approach 2:
The patent transitions from single-face insulation to dual-face insulation, adding insulation in the dimensional space of the opposite face and side walls. By insulating both the first face and the second face of the backplate, the solution addresses current leaks from all surfaces (top, bottom, and side walls of perforation holes) rather than only one face, effectively extending protection to all dimensional exposures.
2Reliability
If insulating layers are placed on the membrane, then current leaks are prevented, but the mechanical properties and sensitivity of the membrane are impacted
Solution Approach 1:
The patent extracts the insulation function from the membrane and relocates it to the backplate. Instead of placing insulating layers on the membrane (which would affect its mechanical properties and sensitivity), the insulation is applied to the backplate's first face and second face. This extraction preserves the membrane's flexibility and acoustic response while still preventing current leaks through the insulating layers on the backplate surfaces.
Solution Approach 2:
The backplate serves as an intermediary structure that carries the insulation function. Rather than insulating the membrane directly, the backplate with its dual insulating layers acts as the mediating element that prevents current leaks while leaving the membrane free to maintain its mechanical properties and sensitivity.
3Reliability
If the backplate is fully encapsulated with insulating material, then current leaks from all surfaces are prevented, but manufacturing complexity increases
Solution Approach 1:
The patent segments the insulation into distinct parts: a first insulating layer on the first face of the backplate and a second insulating layer on the second face of the backplate. This segmentation allows each layer to be applied independently to specific surfaces, simplifying the manufacturing process compared to full encapsulation, while still achieving comprehensive coverage of all current leak pathways including side walls of perforation holes.
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 solution effectively reduces or eliminates current leaks, enhancing the robustness and sensitivity of capacitive microphone systems by ensuring proper insulation and reducing noise and power consumption.
Implementation Method 1
The conductive sections of the backplate are fully or partially encapsulated with insulating material on all vulnerable surfaces, including the top and bottom surfaces and sidewalls of perforation holes, to prevent current leakage
Implementation Method 2
Sound is transduced into electrical signals by detecting the varying capacitance between the membrane and the backplates as the membrane vibrates in response to sound waves
Implementation Method 3
An electrical field is therefore required across the membrane and backplate electrodes. This electrical field is generally supplied by an Application Specific Integrated Circuit (ASIC) in the form of a bias voltage applied across the electrodes
Data Source
AI summary
A capacitive microphone may include a housing, a membrane, and a first backplate, wherein a first insulating layer may be disposed on a first side of the first backplate facing the membrane and a second insulating layer may be disposed on a second side of the first backplate opposite to the first side of the first backplate. A further insulating layer may be disposed on a side wall of at least one of a plurality of perforation holes in the first backplate. Each conductive surface of the first backplate may be covered with insulating material.