Acoustic Diaphragm Fabrication via Segmented Elastomeric Curing

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Solution Overview

Problem

The existing methods for fabricating acoustic diaphragms in miniature earbuds face challenges with surface tension issues in liquid silicone, leading to adhesion, thinning, and the formation of holes or tears during demolding, which compromise the strength and functionality of the compliant member.

Innovation Solution

A method involving the creation of a membrane with multiple elastomeric layers, where one layer is partially cured and another is applied in an uncured state, secured to a bobbin and housing, allowing for controlled curing and demolding without thinning, and the central region is stiffened to form an acoustic diaphragm.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If liquid silicone is used to fabricate acoustic diaphragms in miniature earbuds, then the compliant member can be formed, but surface tension issues cause adhesion, thinning, and formation of holes or tears during demolding

Engineering Contradiction:

Improvefabrication of acoustic diaphragmVSAvoidstrength of compliant member

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent divides the elastomeric material into multiple layers: a first elastomeric layer that is cured to form a stable base membrane, and a second uncured elastomeric layer that is applied over it. This segmentation allows the first layer to provide structural integrity while the second layer can be easily removed, preventing adhesion and tearing issues during demolding.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first elastomeric layer is cured before applying the second elastomeric layer. This preliminary curing action creates a stable foundation that prevents the uncured material from adhering to the mold, thereby preventing thinning and holes during subsequent demolding operations.

Inventive Principle:

Principle #10Preliminary action

2Volume of moving object

If the elastomeric layer is made thin to achieve miniaturization, then the device size is reduced, but the compliant member becomes weaker and more prone to holes and tears

Engineering Contradiction:

Improvesize of earbudVSAvoidstrength of compliant member

Core Design Contradiction:

Volume of moving objectVSStrength

Solution Approach 1:

By segmenting the elastomeric material into multiple layers with different curing states, the patent enables the use of thinner overall material while maintaining strength. The cured first layer provides structural integrity even when the total thickness is reduced for miniaturization.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent uses a composite structure combining cured and uncured elastomeric layers. This composite approach allows the thin structure needed for miniaturization to maintain sufficient strength, as the cured first layer provides a strong foundation that prevents tearing and hole formation.

Inventive Principle:

Principle #40Composite materials

3Strength

If the elastomeric layer is made thick to prevent holes and tears, then the compliant member strength is improved, but the device size increases

Engineering Contradiction:

Improvedurability of compliant memberVSAvoidsize of earbud

Core Design Contradiction:

StrengthVSVolume of moving object

Solution Approach 1:

The segmented layer structure allows the first cured layer to be relatively thin yet still provide sufficient strength and structural integrity. The uncured second layer can be even thinner since it does not need to bear structural loads, enabling overall thickness reduction while maintaining durability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the elastomeric structure have different properties: the first layer is cured to provide local structural strength and stability, while the second layer remains uncured to enable easy demolding. This local differentiation of material properties allows thin overall design with sufficient localized strength.

Inventive Principle:

Principle #3Local quality

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

This approach results in a stronger, more consistently stiffened acoustic diaphragm with reduced thinning and improved durability, preventing holes and tears, and enhancing the acoustic performance by maintaining the structural integrity of the compliant member.

Implementation Method 1

The uncured elastomeric layer is cured such that is it secured to the membrane and to the housing and/or the bobbin

Methodology Applied

Scientific EffectUltraviolet light curing: Photopolymerisation

Implementation Method 2

Curing the another elastomeric layer may include applying heat or ultraviolet light to the another elastomeric layer

Methodology Applied

Scientific EffectHeat curing: Heating

Data Source

PatentUS11546696B2Miniature device having an acoustic diaphragm

Publication Date: 2023.01.03 BOSE CORP

AI summary

A method of forming a device having a compliant member includes creating a membrane having one or more elastomeric layers which are at least partially cured. Another elastomeric layer is provided on the membrane in an uncured state. At least one of a bobbin and a housing are positioned so that an end of the bobbin or housing, or the ends of both the bobbin and housing, extend at least partially into the uncured elastomeric layer. The uncured elastomeric layer is then cured to secure it to the membrane and to the housing or bobbin, or both the housing and bobbin. The method substantially reduces or eliminates the formation of holes that can form during fabrication or use of the device.