Microphone Porting Structure for Bottom-Ported Mic Sealing

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Solution Overview

Problem

Existing microphone array arrangements in portable communication devices face challenges in aligning microphones in the z-direction, particularly in handheld radio applications, due to physical constraints and acoustic performance tradeoffs, making it difficult to seal and achieve effective noise cancellation and beam forming.

Innovation Solution

A microphone porting structure with a substrate having a planar bearing surface and a through-hole, allowing for closer alignment and sealing of bottom ported microphones, which includes configurations with straight or bent porting through-holes to optimize acoustic alignment and sealing, enabling tighter spacing and improved environmental sealing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If top ported microphones are used to save space and establish noise cancelling vector, then space is saved and noise cancelling is achieved, but the devices become difficult to seal and acoustic performance is compromised

Engineering Contradiction:

ImprovespaceVSAvoidsealing capability

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The patent inverts the traditional top-ported microphone configuration by using bottom-ported microphones. This inversion allows the acoustic port to face downward toward the PCB, enabling effective sealing between the microphone diaphragm and the PCB surface, while still achieving the required noise cancelling vector through proper acoustic port alignment.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent transitions from vertical (top-ported) to horizontal (bottom-ported) acoustic port orientation. This dimensional change in porting direction enables the microphone to be sealed against the PCB while maintaining the acoustic vector normal to the PCB, resolving the sealing problem inherent in top-ported configurations.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Measurement precision

If microphones are positioned closer together for better alignment in z-direction, then alignment improves, but sealing becomes more difficult and acoustic performance is compromised

Engineering Contradiction:

Improvealignment precisionVSAvoidsealing capability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

By inverting to bottom-ported microphones, the patent enables closer microphone spacing while maintaining sealing capability. The bottom porting configuration allows the acoustic ports to align with PCB openings for sealing, whereas top porting would require larger spacing to accommodate the upward-facing ports.

Inventive Principle:

Principle #13The other way round (Inversion)

3Volume of moving object

If outward porting is used for top ported microphones, then space is saved, but the devices become difficult to seal

Engineering Contradiction:

ImprovespaceVSAvoidsealing ease

Core Design Contradiction:

Volume of moving objectVSEase of manufacture

Solution Approach 1:

The patent inverts the porting direction from outward (top) to inward (bottom) toward the PCB. This inversion enables the acoustic ports to be sealed against the PCB surface, making the device easier to manufacture with proper sealing, while still achieving compact space utilization.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS9648434B1Microphone porting structure and assembly for a communication device

Publication Date: 2017.05.09 MOTOROLA SOLUTIONS INC

AI summary

A microphone porting structure, comprises a substrate (312) having a bearing surface and a porting through-hole (344) formed therethough for aligning with a microphone port of a bottom ported microphone (334). The bearing surface provides an area against which to seal and the through-hole provides for acoustic path alignment for the audio ports of paired bottom ported microphones mounted to a printed circuit board.