Surface-Mount Microphone Sealed Cavity Design
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Solution Overview
Problem
Existing sound sensing devices for vehicles are susceptible to damage from harsh environmental conditions due to their exposure and require protection without compromising acoustic performance.
Innovation Solution
A surface-mounted sound sensing device with a housing and a PCBA that creates a sealed cavity with a structure panel, using an adhesive member to seal the microphone element and a vent with a dense mesh layer to balance static air pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a port hole is provided for direct air path to achieve good acoustic performance, then acoustic sensitivity and bandwidth are improved, but the microphone element becomes susceptible to damage from harsh environmental conditions
Solution Approach 1:
The patent introduces an acoustic membrane as an intermediary component between the external environment and the microphone element. This membrane allows acoustic waves to pass through to the microphone while blocking water, dust, and other contaminants, thus mediating between the need for acoustic access and environmental protection requirements
Solution Approach 2:
The patent employs a thin acoustic membrane that is flexible enough to allow sound wave transmission while providing a protective barrier. The membrane's thin and flexible nature ensures minimal acoustic degradation while maintaining effective protection against harsh environmental conditions
2Reliability
If acoustic mesh or membrane with small pore sizes is used to block dust and water, then environmental protection is improved, but the membrane becomes easily damaged by sharp objects and may allow liquid penetration under high pressure
Solution Approach 1:
The patent uses composite material construction for the acoustic membrane, combining materials with different properties to achieve both porosity for acoustic transmission and sufficient mechanical strength. The composite structure allows the membrane to maintain small pore sizes for blocking contaminants while incorporating stronger material phases to resist damage from sharp objects and high pressure
3Reliability
If an accelerometer-based solution is used to measure sound-induced vibration, then weatherproofing is achieved, but the device size becomes much larger making integration difficult
Solution Approach 1:
The patent uses a thin acoustic membrane instead of large piezo-diaphragms, allowing for a much more compact microphone element integration. The membrane approach enables weatherproofing while maintaining a small form factor suitable for automotive applications where space is constrained
Solution Approach 2:
The patent essentially creates a protected version of the traditional microphone element design, copying the core microphone technology but adding the acoustic membrane protection layer. This allows maintaining the small size advantage of microphone elements while achieving the weatherproofing特性 of accelerometer-based solutions
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 provides environmental protection for the microphone element, meets high ingress protection ratings, and maintains good acoustic performance while being aesthetically hidden within the vehicle structure.
Implementation Method 1
a vent with a dense mesh layer to balance static air pressure
Implementation Method 2
an adhesive member sealed to both a perimeter edge of one end of the housing and a structure panel defining a sealed cavity
Implementation Method 3
It is also difficult for liquid molecules to pass through due to the large surface tension formed among liquid molecules
Implementation Method 4
The micropores are big enough to allow air molecules to pass through yet are small enough to block dust particles
Data Source
AI summary
A sound and vibration sensor having a sealed cavity defined between a microphone element and structure panel and an area below the microphone element wherein the microphone element senses a change in acoustic pressure inside the sealed cavity caused by sound waves striking the structure panel.