Dual Diaphragm Microphone Module for Sensitivity and Volume Trade-off
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Solution Overview
Problem
Conventional microphones with a single sensing structure suffer from reduced sensitivity due to high air resistance in the cavity, leading to less clear signals.
Innovation Solution
A microphone module with two sensing structures and a communicating cavity design, where the diaphragms of both structures vibrate in tandem, increasing amplitude and sensitivity, and the cavity's axial size is greater than its radial size to enhance directional sensing and reduce volume, improving signal-to-noise ratio and high-frequency response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single sensing structure is used in the microphone module, then the device complexity is reduced, but the sensitivity is reduced due to high air resistance in the cavity
Solution Approach 1:
The microphone module divides the single sensing function into two separate sensing structures (first and second sensing structures with respective diaphragms). Each sensing structure independently converts acoustic waves into electrical signals, effectively segmenting the sensing task to reduce air resistance interference and improve overall sensitivity while maintaining manageable device complexity through modular design
Solution Approach 2:
The patent combines two sensing structures into a unified microphone module system where both diaphragms work together to detect sound waves. The housing integrates both sensing structures within a single cavity, merging their functions while allowing each to contribute independently to the overall signal, thereby improving sensitivity without proportionally increasing complexity
2Measurement precision
If the cavity size is increased to reduce air resistance, then the sensitivity improves, but the volume of the microphone module increases
Solution Approach 1:
The patent optimizes the cavity geometry by making the axial length greater than the radial dimensions, creating an elongated cylindrical cavity. This dimensional approach allows the cavity to provide sufficient volume for reduced air resistance and improved sensitivity while minimizing the overall footprint and volume of the microphone module through efficient spatial utilization
Solution Approach 2:
The patent changes the geometric parameters of the cavity by specifying that the axial length should be greater than the radial dimensions. This parameter optimization allows the cavity to achieve the necessary volume for reduced air resistance without increasing the overall module volume, as the elongated shape fits more efficiently within the housing constraints
3Measurement precision
If two sensing structures are used to improve sensitivity, then the signal quality improves, but the device complexity increases
Solution Approach 1:
The housing serves multiple functions: it encloses both sensing structures, provides the acoustic cavity for sound wave propagation, and integrates the electrical connection paths for both diaphragms. This multi-functionality reduces the need for separate structural elements, thereby improving signal quality through dual sensing while controlling overall device complexity
Solution Approach 2:
The first and second sensing structures are nested within the same housing cavity, with each diaphragm positioned to face the sound inlet from opposite directions. This nested arrangement allows both sensing structures to share the same acoustic environment and housing space, improving signal quality through redundancy and diversity while minimizing the increase in device complexity through space-efficient integration
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 dual sensing structure design enhances sensitivity and signal quality, increases the acoustic overload point, and allows for adjustable directional output, improving overall performance compared to single-sensing structure microphones.
Implementation Method 1
The sound enables the diaphragm of the sensing structure in the microphone module to vibrate
Implementation Method 2
when the diaphragm of each of the sensing structures vibrates, the diaphragm is subjected to the pushing or pulling force exerted by the diaphragm of the other sensing structure to the air in the communicating cavity
Data Source
AI summary
A microphone module, including a substrate assembly, two sensing structures, and two housings, is provided. The substrate assembly has at least one through hole and at least one circuit structure electrically connected to at least one pad. The through hole includes two holes formed on opposite sides of the substrate assembly. The sensing structures are disposed on and cover the two holes. The two sensing structures and the through hole collectively form a communicating cavity. A size of the communicating cavity in an axial direction is greater than that in a radial direction. The two housings are respectively disposed on the opposite sides of the substrate assembly and respectively shield the two sensing structures. Each of the housings, the substrate assembly, and the corresponding sensing structure form an inner cavity. The housings each has a sound hole. The inner cavity communicates with the outside through the sound hole.