Closed Cell Foam Microphone Body for Environmental Protection

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Solution Overview

Problem

Conventional microphones using open-cell foam materials and thin membranes for sound transmission are prone to mechanical and physical compromise, leading to potential sound transmission loss and environmental exposure issues.

Innovation Solution

A microphone design employing a closed-cell foam body between the transducer and the sound reception area, eliminating the need for an acoustic PTFE membrane while maintaining effective sound transmission and environmental protection, with a closed-cell foam material that exhibits minimal sound insertion loss in the 300 to 3400 Hz frequency band.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If open-cell foam material and thin membrane are used for sound transmission media, then mechanical protection and environmental resistance are provided, but sound transmission loss increases and mechanical reliability decreases

Engineering Contradiction:
Improvemechanical reliabilityVSAvoidsound transmission loss
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent removes the thin membrane component from the traditional microphone structure. By extracting this weak element, the invention eliminates the source of mechanical failures and sound transmission losses while maintaining environmental protection through the closed-cell foam alone

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention changes the fundamental parameter of the foam material from open-cell to closed-cell structure. This parameter change transforms the material properties to provide both mechanical protection and acoustic transparency, resolving the contradiction between durability and sound transmission

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If thin membrane is used to protect transducer from water and particulates, then environmental protection is improved, but mechanical strength and reliability deteriorate

Engineering Contradiction:
Improveenvironmental protectionVSAvoidmechanical strength
Core Design Contradiction:
Object-affected harmful factorsVSStrength

Solution Approach 1:

The patent changes the cell structure parameter of the foam from open to closed, creating a material that is inherently resistant to water and particulate intrusion while maintaining high mechanical strength. The closed cells act as natural barriers without requiring additional membrane layers

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The closed-cell foam material performs multiple functions simultaneously: it provides mechanical protection, environmental resistance to water and particulates, and maintains acoustic transparency. This single material replaces the traditional multi-component system of open-cell foam plus membrane

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Object-affected harmful factors

If multiple components (open-cell foam and membrane) are used for protection, then environmental resistance is improved, but device complexity increases

Engineering Contradiction:
Improveenvironmental resistanceVSAvoidstructure complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent merges the protective functions previously distributed across multiple components (open-cell foam and membrane) into a single closed-cell foam material. This consolidation simplifies the structure while maintaining or improving environmental resistance

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The closed-cell foam serves as a universal protective element that simultaneously provides mechanical protection, water resistance, and particulate filtration, eliminating the need for separate membrane components and reducing overall device complexity

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 closed-cell foam effectively protects the transducer from environmental elements without significant sound transmission loss, achieving good voice transmission and wind buffeting mitigation with fewer parts, and passing environmental tests.

Implementation Method 1

a closed cell foam body positioned between the transducer and an area for receiving ambient sound

Methodology Applied
Scientific EffectSound transmission: Sound

Implementation Method 2

The foam provides mechanical and wind buffeting protection

Methodology Applied
Scientific EffectWind buffeting resistance: Drag

Data Source

PatentEP3050315B1Microphone having closed cell foam body
Publication Date: 2020.03.11 3M INNOVATIVE PROPERTIES CO
  • EP3050315B1 patent drawingFigure 1~2
  • EP3050315B1 patent drawingFigure 3~4

AI summary

A microphone 10 that comprises a transducer 12 and a closed cell foam body 18, 20 positioned between the transducer 12 and an opening 25 fashioned for receiving ambient sound. The microphone 10 is protected from external factors without exhibiting substantial sound transmission loss while using few parts. Good voice transmission, wind buffeting mitigation, and environmental protection can be achieved with a single material.