MEMS Microphone Cross-Beam Assembly for Diaphragm Sensitivity
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Solution Overview
Problem
The sensitivity of MEMS microphones with double vibration diaphragms is affected due to insufficient compliance of the vibration diaphragms.
Innovation Solution
A MEMS microphone design featuring a cross beam assembly and sub-vibration diaphragm assemblies with slits and gaps, forming a cantilever beam structure, which increases compliance and improves sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If double vibration diaphragms are used to achieve waterproof and dustproof effects, then waterproof and dustproof performance is improved, but compliance of the vibration diaphragm is insufficient, affecting sensitivity
Solution Approach 1:
The vibration diaphragm system is divided into multiple sub-vibration diaphragms (first, second, and third sub-vibration diaphragms) that are arranged in series. Each sub-vibration diaphragm can move independently, providing both waterproof sealing between layers and sufficient overall compliance for sensitivity. The segmentation allows each layer to contribute to both sealing and vibration response.
Solution Approach 2:
The patent transitions from a single-plane vibration diaphragm to a multi-layer stacked structure with sub-vibration diaphragms arranged in the depth dimension. This three-dimensional arrangement maintains waterproof sealing between layers while allowing each sub-vibration diaphragm to contribute to the overall compliance, effectively solving the contradiction between sealing and sensitivity.
2Object-generated harmful factors
If air is removed to form a near-vacuum state between double vibration diaphragms, then background noise is reduced, but compliance of the vibration diaphragm is further reduced, affecting sensitivity
Solution Approach 1:
The vibration diaphragm system is segmented into multiple independent sub-vibration diaphragms that can move relative to each other. Even in a near-vacuum state, each sub-vibration diaphragm maintains its compliance, and their combined effect provides sufficient overall compliance for sensitivity while the vacuum state reduces background noise.
Solution Approach 2:
Multiple sub-vibration diaphragms are combined in a stacked arrangement where each contributes to the overall compliance. The series arrangement of these compliant elements maintains total compliance even when the internal pressure is reduced to near-vacuum, allowing noise reduction without sacrificing sensitivity.
3Ease of manufacture
If single back plate electrode or double back plate electrodes are used, then manufacturing is simplified, but waterproof and dustproof effects are not adequately achieved
Solution Approach 1:
The back plate electrode is segmented into multiple back plate electrodes corresponding to each sub-vibration diaphragm layer. This segmentation creates multiple sealing interfaces between vibration diaphragms and back plate electrodes, achieving effective waterproof and dustproof protection while maintaining a relatively simple manufacturing process through standardized layer assembly.
Solution Approach 2:
The patent moves from a single back plate electrode configuration to a multi-layer stacked structure with back plate electrodes at different depths. This three-dimensional arrangement provides multiple sealing planes for waterproof and dustproof protection while maintaining manufacturing simplicity through repetitive layer assembly processes.
Data Source
AI summary
A MEMS microphone includes a substrate having a back cavity, a vibration diaphragm system, and a housing. The vibration diaphragm system includes at least two sub-vibration diaphragm assemblies, a slit is formed between adjacent two of the at least two sub-vibration diaphragm assemblies, one end, distal from the housing, of each of the at least two sub-vibration diaphragm assemblies is fixed to a cross beam assembly, and first gaps are formed between the at least two sub-vibration diaphragm assemblies and inner sides of the housing, so that the at least two sub-vibration diaphragm assemblies form a cantilever beam structure, which increases compliance of the vibration diaphragm system and further improves sensitivity of microphones.