Microphone Ingress Protection Isolation Plate Design
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Solution Overview
Problem
Mobile computing devices face challenges in maintaining microphone performance and ingress protection during assembly due to deformation or displacement of membrane assemblies caused by shear forces, which can lead to inconsistent acoustic and ingress protection performance.
Innovation Solution
The implementation of an acoustic channel with a microphone port, a membrane assembly, and an isolation plate that is rigidly affixed to the housing rather than the membrane, reducing shear force impact on the membrane assembly and preventing deformation, along with an angled design to minimize installation forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a membrane assembly is used to allow microphone exposure while maintaining ingress protection, then ingress protection performance is improved, but the membrane assembly is easily disrupted during assembly which reduces microphone performance and ingress protection performance
Solution Approach 1:
The device is divided into separate functional modules: the membrane assembly is isolated from the acoustic channel by an isolation plate, allowing the membrane to be protected from assembly forces while the acoustic channel components can be assembled independently. This segmentation prevents the membrane from being disrupted during assembly operations.
Solution Approach 2:
An isolation plate is introduced as an intermediary component between the membrane assembly and the acoustic channel. This isolation plate absorbs and redirects assembly forces, preventing direct transmission of shear forces to the membrane assembly during device assembly, thereby protecting the membrane from disruption.
2Manufacturing precision
If the isolation plate is affixed to the housing rather than the membrane, then shear force impact on the membrane assembly is reduced, but the device complexity increases
Solution Approach 1:
The isolation plate creates a clear separation between the membrane assembly mounting and the acoustic channel mounting. By affixing the isolation plate to the housing rather than the membrane, the system segments the force transmission paths, allowing precise control over shear force application and maintaining membrane assembly integrity.
3Ease of manufacture
If an angled design is used to minimize installation forces, then assembly disruption is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The acoustic channel is designed with an angled configuration rather than a straight alignment, creating an asymmetric path that naturally redirects assembly forces. This angled design minimizes the transmission of installation forces to the membrane assembly, reducing assembly disruption while the isolation plate ensures consistent force distribution.
Data Source
AI summary
A mobile computing device includes: a housing having a front face, an opposing back face, and side walls joining the front and back faces; a microphone supported within the housing; and an acoustic channel extending between the microphone and an exterior of the housing, the acoustic channel defined by: (i) a microphone port traversing one of the side walls; (ii) a membrane assembly affixed to a first inner housing surface around the microphone port; and (iii) an isolation plate affixed to a second inner housing surface surrounding at least a portion of the first inner housing surface, the isolation plate having a channel opening therethrough and configured to engage with the membrane assembly.