Acoustic Membrane Laminate With Peripheral Bonding
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Solution Overview
Problem
Conventional acoustic vents with PTFE membranes and support layers face issues with dampened acoustic signal transmission and compromised waterproof ratings due to lamination, which can lead to water intrusion and mechanical damage, especially in small portable electronic devices.
Innovation Solution
A microporous membrane laminate comprising a PTFE membrane with an average pore size between 0.05 μm and 2 μm, laminated with a scrim layer, which maintains the water entry pressure of the PTFE membrane while reducing thickness and enhancing acoustic performance by minimizing insertion loss and harmonic distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a support layer is laminated to the PTFE membrane, then mechanical strength and handling ease are improved, but acoustic signal transmission is dampened
Solution Approach 1:
The patent applies local quality by creating an unbonded region in the center of the laminate that allows acoustic signals to pass through without damping, while bonded peripheral regions provide mechanical strength and sealing. The adhesive is applied only in a peripheral region, leaving a central unbonded region that preserves acoustic transmission properties.
Solution Approach 2:
The patent segments the laminate into distinct functional zones: a peripheral bonded region for mechanical support and sealing, and a central unbonded region for acoustic transmission. This segmentation allows each zone to optimize its specific function without compromising the other.
2Ease of operation
If a support layer is laminated to the PTFE membrane, then handling ease is improved, but waterproof rating is compromised due to adhesive placement on the support layer surface
Solution Approach 1:
The patent applies local quality by positioning the adhesive in a peripheral region rather than covering the entire support layer surface. This allows the adhesive to provide sufficient bonding for handling while leaving the PTFE membrane's water-repellent properties exposed in the central region for waterproof sealing.
Solution Approach 2:
Instead of placing adhesive on the support layer surface as in conventional designs, the patent inverts the approach by applying adhesive only in peripheral regions, allowing the PTFE membrane itself to serve as the primary waterproof barrier in the central unbonded region.
3Strength
If the support layer thickness is increased, then mechanical strength is improved, but the adhesive cannot make sealing contact with the PTFE membrane
Solution Approach 1:
The patent segments the adhesive bonding region from the acoustic transmission region. The adhesive is confined to peripheral regions where it bonds the support layer to the housing, while the central unbonded region maintains direct acoustic coupling between the PTFE membrane and the housing opening, eliminating the need for adhesive to bridge the full support layer thickness.
Solution Approach 2:
The patent transitions from a conventional single-layer bonding approach to a multi-dimensional bonding strategy, where adhesive is applied in a peripheral annular region rather than uniformly across the surface. This dimensional repositioning allows the adhesive to provide mechanical bonding without interfering with the acoustic path through the PTFE membrane.
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 laminate achieves improved acoustic performance with increased insertion loss and reduced harmonic distortion compared to PTFE-only membranes, while maintaining the waterproof rating and preventing water intrusion, even under mechanical stress and varying pressures.
Implementation Method 1
PTFE membranes can be manufactured to have low basis weight and high flexibility. These properties allow them to vibrate easily when excited by an acoustic signal, and transmit the acoustic signal to the other side without allowing liquid intrusion.
Implementation Method 2
PTFE membrane also has high dust efficiency and can withstand high differential water pressure without any liquid water passing through.
Implementation Method 3
PTFE membranes are gas permeable, allowing equalizations of differential pressures due to temperature changes, as well as the evacuation of moisture due to condensation.
Implementation Method 4
The acoustic membrane laminate has a water entry pressure that is substantially equal to that of the PTFE membrane.
Data Source
AI summary
The technology described herein generally relates to a microporous membrane laminate for acoustic venting. In one embodiment, the technology disclosed herein is a polytetrafluoroethylene (PTFE) membrane having an average pore size between 0.05 μm and 2 μm and a scrim layer laminated to the PTFE membrane to form an acoustic membrane laminate. The acoustic membrane laminate has a thickness between 10 μm and 60 μm, and the scrim layer defines an average scrim opening between 0.20 mm2 and 5.0 mm2. The acoustic membrane laminate exhibits an increased average insertion loss in a frequency range from 300 Hz to 3000 Hz compared to the PTFE membrane alone, and has a decreased total harmonic distortion relative to the PTFE membrane alone. The acoustic membrane laminate has a water entry pressure that is substantially equal to that of the PTFE membrane.