Elastomer Nonwoven Sound Membrane for Low Insertion Loss
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Solution Overview
Problem
Existing sound-transmitting membranes, particularly those using nonwoven fabrics as supports, fail to exhibit good acoustic characteristics, especially in the high-frequency range, and do not adequately address the need for both sound transmissibility and prevention of foreign matter entry.
Innovation Solution
A sound-transmitting membrane is developed using a nonwoven fabric with an elastomer as a supporting member, layered with a resin porous membrane containing polytetrafluoroethylene (PTFE) to enhance sound transmissibility and prevent foreign matter entry, with specific adjustments in pore diameter and surface density to minimize insertion loss across various frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a nonwoven fabric is used as a support for the sound-transmitting membrane, then the ease of manufacture and flexibility are improved, but the acoustic characteristics especially in the high-frequency range deteriorate
Solution Approach 1:
The invention changes the material parameter of the nonwoven fabric from conventional types to elastomer-based nonwoven fabric, which fundamentally alters the acoustic properties while maintaining manufacturability. This parameter change resolves the contradiction by selecting a material that inherently provides both ease of manufacture and good high-frequency acoustic characteristics.
Solution Approach 2:
The invention uses a composite structure combining elastomer nonwoven fabric as support with porous plastic membrane layers. This composite material approach allows the elastomer to provide mechanical flexibility and ease of manufacture while the porous plastic membrane ensures good acoustic characteristics across all frequency ranges including high frequencies.
2Reliability
If the surface density of the sound-transmitting membrane is reduced to maintain sound transmissibility, then the sound transmissibility is improved, but the prevention of foreign matter entry deteriorates
Solution Approach 1:
The invention applies different functional qualities to different layers of the membrane structure. The porous plastic membrane layers provide both sound transmissibility and foreign matter prevention locally, while the elastomer nonwoven fabric support provides mechanical properties. This local quality differentiation allows the membrane to achieve both sound transmission and waterproofing without compromising either function.
Solution Approach 2:
The invention utilizes porous plastic membrane materials that have optimized pore structures. These porous materials allow sound waves to pass through while blocking foreign matters like water drops, resolving the contradiction between sound transmissibility and foreign matter prevention by carefully selecting and designing the porous structure parameters.
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 membrane achieves low insertion loss for high-frequency sounds, maintaining consistent sound transmissibility across a wide frequency range while preventing foreign matter entry, thus improving the acoustic characteristics and waterproof properties of electronic devices.
Implementation Method 1
a resin porous membrane layered on the supporting member and containing polytetrafluoroethylene as a main component
Implementation Method 2
The supporting member is a nonwoven fabric containing an elastomer
Data Source
AI summary
A sound-transmitting membrane (1) is provided that allows passage of sounds and prevents passage of foreign matters, the sound-transmitting membrane (1) including a supporting member (12) and a resin porous membrane (11) layered on the supporting member (12) and containing polytetrafluoroethylene as a main component. The supporting member (12) is a nonwoven fabric containing an elastomer. Since the supporting member (12) is a nonwoven fabric containing an elastomer, the insertion loss of the sound-transmitting membrane can be reduced for sounds of 3000 Hz.