Earphone Bushing with Flexible Extended Portion for Sound Leakage Reduction
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Solution Overview
Problem
Conventional earphones with resin-molded housings suffer from significant sound leakage due to gaps created during ultrasonic welding or adhesive bonding, which compromises sound isolation, especially in environments where minimal sound leakage is desired.
Innovation Solution
The earphone employs a dual housing structure with a bushing that has a cord holding portion and an extended portion made of flexible material, such as silicon rubber, which covers the inner surface of the housing and the stepped faying surface between the front and rear housings, creating additional barriers to sound leakage and reducing the number of components needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If ultrasonic welding or adhesive bonding is used to combine front and rear housings, then the housings can be assembled efficiently, but gaps are created between faying surfaces causing sound leakage
Solution Approach 1:
A foam material is introduced as an intermediary substance between the front and rear housings. This foam fills the gaps at the faying surfaces and back cavity, preventing sound leakage while allowing the housings to be combined using conventional ultrasonic welding or adhesive bonding methods. The foam acts as a mediator that resolves the conflict between assembly efficiency and sound isolation.
Solution Approach 2:
The foam material functions as a flexible sealing layer that conforms to the gaps and irregularities at the faying surfaces between housings. This flexible material effectively blocks sound leakage paths without requiring precise manufacturing tolerances or complex sealing structures.
2Ease of manufacture
If resin-molded housings are used, then manufacturing is simplified and cost is reduced, but sound isolation performance is insufficient
Solution Approach 1:
The earphone housing system becomes a composite structure combining resin-molded housings with foam material. The resin housings provide structural integrity and manufacturing simplicity, while the foam material provides sound isolation. This composite approach maintains the advantages of resin molding while adding sound leakage prevention capabilities.
3Ease of manufacture
If gaps are created between faying surfaces during assembly, then assembly tolerance is relaxed, but sound leakage increases
Solution Approach 1:
The foam material serves as an intermediary that fills the gaps created during assembly, allowing relaxed tolerances at faying surfaces. The foam conformally fills irregularities and gaps, ensuring sound isolation is maintained even when assembly tolerances are not tightly controlled.
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 configuration significantly reduces sound leakage by creating multiple barriers and utilizing a flexible material to enhance sound attenuation, maintaining stable sound quality without the need for conventional sound-quality adjustment holes.
Implementation Method 1
a bushing having a cord holding portion that holds a cord that carries an audio signal to the speaker unit and is running to the outside of the housing, and having an extended portion that is extended into the housing and spread along an inner surface of the housing
Data Source
AI summary
An earphone includes a speaker unit, a housing that covers a rear surface of the speaker unit, and a bushing having a cord holding portion that holds a cord that carries an audio signal to the speaker unit and is running to the outside of the housing. The bushing also has an extended portion that is extended into the housing and spread along an inner surface of the housing. The inner surface of the housing faces the rear surface of the speaker unit.