Electret Diaphragm Bonding Layer Adhesion
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Solution Overview
Problem
Traditional electret flexible speakers face challenges with porous polytetrafluoroethylene (PTFE) films due to difficulties in adhering to electrode layers, medium charge storage stability at high porosity, low elastic modulus, and easy plastic deformation, hindering the development of efficient and cost-effective electret diaphragms for futuristic audio systems.
Innovation Solution
An electret diaphragm comprising an electret layer with an ethylene group polymer, a bonding layer of ethylene-ethyl-acrylate (EEA) or ethylene-vinyl acetate (EVA), and an aluminum electrode layer, which enhances charge storage capacity and adhesion, while maintaining a light mass and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If porous PTFE films are used as electret material, then charge storage capability is improved, but adhesion to electrode layer deteriorates
Solution Approach 1:
A bonding layer made of EEA or EVA polymer is introduced as an intermediary between the porous PTFE electret layer and the aluminum electrode layer. This bonding layer serves as a mediator that provides both adhesion to the PTFE surface and compatibility with the aluminum electrode, resolving the adhesion problem while preserving the charge storage capability of the PTFE.
Solution Approach 2:
The electret diaphragm is constructed as a composite material system consisting of multiple layers: porous PTFE electret layer, EEA/EVA bonding layer, and aluminum electrode layer. This composite structure combines the charge storage properties of PTFE with the adhesion properties of the bonding layer, achieving both requirements simultaneously.
2Quantity of substance
If high porosity is used in PTFE film, then charge storage capability is improved, but charge storage stability deteriorates
Solution Approach 1:
The composite structure with EEA/EVA bonding layer provides structural support and stabilization to the high-porosity PTFE electret layer. The bonding layer acts as a matrix that maintains the spatial arrangement of the porous structure while preventing charge leakage, thereby improving charge storage stability without sacrificing capability.
3Quantity of substance
If porous PTFE film is used, then charge storage capability is improved, but mechanical strength deteriorates
Solution Approach 1:
The EEA/EVA bonding layer and aluminum electrode layer form a composite structure that provides mechanical reinforcement to the porous PTFE electret layer. The bonding layer acts as a structural matrix that maintains the integrity of the porous network, while the aluminum layer provides additional mechanical support, together improving overall mechanical strength while preserving charge storage capability.
Solution Approach 2:
The electret diaphragm is segmented into multiple functional layers, each with specific roles. The porous PTFE layer is dedicated to charge storage, while the EEA/EVA bonding layer and aluminum electrode layer handle mechanical support and electrical functions, allowing each layer to be optimized for its specific function without compromise.
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 proposed solution significantly improves charge storage stability, elastic modulus, and adhesion to the aluminum electrode, resulting in an electret diaphragm with enhanced performance, including an 80% increase in surface potential and improved mechanical strength, leading to a more efficient and cost-effective flexible electret speaker with improved sound pressure levels.
Implementation Method 1
an electret-based diaphragm is placed beside perforated electrode layers and separated by a set of spacers. The speaker operates in membrane vibration mode, interaction between the externally applied voltage and space charge of an electret induced vibration on the diaphragm
Implementation Method 2
a bonding layer adhered to a surface of the electret layer
Data Source
AI summary
An electret diaphragm and a speaker using the same are provided. The electret diaphragm includes an electret layer, a bonding layer adhered to a surface of the electret layer, and an aluminum (Al) electrode layer adhered on the bonding layer. The electret layer at least includes ethylene group polymer. A material of the bonding layer is ethylene-ethyl-acrylate (EEA) or ethylene-vinyl acetate (EVA).