Waterproof Sound-Transmitting Membrane with Liquid-Repellent Layer
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Solution Overview
Problem
The reduction in size of electronic device openings leads to a decrease in the effective area of waterproof sound-transmitting membranes, resulting in deteriorated acoustic characteristics, as existing solutions do not effectively address sound transmission and water prevention at reduced membrane sizes.
Innovation Solution
A non-porous resin film with through holes and a liquid-repellent layer, where the through holes have a diameter of 4.0 μm to 12.0 μm and a through-thickness air permeability of 2.0 cm3/(cm2·second) to 50 cm3/(cm2·second, ensuring both sound transmission and water exclusion even at reduced effective areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the opening size is reduced to decrease device size, then the effective area of the waterproof sound-transmitting membrane is reduced, but the sound transmission characteristics deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the through-hole diameter (4.0-12.0 μm) and air permeability (2.0-50 cm3/(cm2·second)) of the waterproof sound-transmitting membrane. This allows the membrane to maintain excellent sound transmission characteristics even when the effective area is reduced, resolving the contradiction between device size reduction and sound quality maintenance.
2Volume of moving object
If the opening size is reduced to decrease device size, then the effective area of the waterproof sound-transmitting membrane is reduced, but water prevention capability may be compromised
Solution Approach 1:
The patent employs parameter changes by optimizing the through-hole diameter (4.0-12.0 μm) and air permeability (2.0-50 cm3/(cm2·second)) of the membrane. These controlled parameters enable the membrane to achieve both waterproofness (water entry pressure of 10 kPa or more) and sound transmissivity, even at reduced effective areas.
Solution Approach 2:
The patent utilizes composite materials by combining a non-porous resin film with a liquid-repellent layer. This composite structure provides both waterproofing and sound transmission functions, allowing the membrane to maintain water prevention capability while enabling sound passage through the controlled through-holes.
3Reliability
If a non-porous resin film with through holes is used, then sound transmission is enabled, but water may enter through the holes
Solution Approach 1:
The patent applies composite materials by combining a non-porous resin film with through holes and a liquid-repellent layer. The resin film enables sound transmission through its controlled porosity, while the liquid-repellent layer prevents water from penetrating through the through-holes, thus resolving the contradiction between sound transmission and water prevention.
Solution Approach 2:
The patent uses parameter changes by precisely controlling the through-hole diameter (4.0-12.0 μm) and air permeability (2.0-50 cm3/(cm2·second)). These parameter optimizations allow the membrane to transmit sound effectively while the liquid-repellent layer maintains waterproofness, preventing water entry through the through-holes.
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 solution maintains sound transmission quality and prevents water entry with a sound pressure loss of 1 dB or less at frequencies from 100 Hz to 3 kHz, even at small effective areas, while achieving a water entry pressure of 10 kPa or more, enhancing the design flexibility and waterproofness of electronic devices.
Implementation Method 1
a liquid-repellent layer formed on a principal surface of the resin film
Data Source
AI summary
A waterproof sound-transmitting membrane of the present disclosure includes: a non-porous resin film having formed therein a plurality of through holes extending through a thickness of the non-porous resin film; and a liquid-repellent layer formed on a principal surface of the resin film and having openings at positions corresponding to positions of the plurality of through holes. The through holes have a diameter of 4.0 μm or more and 12.0 μm or less, and the waterproof sound-transmitting membrane has a through-thickness air permeability of 2.0 cm3/(cm2·second) or more and 50 cm3/(cm2·second) or less in terms of Frazier number as measured according to JIS L 1096. With this waterproof sound-transmitting membrane placed over an opening of a housing of an electronic device or the like, entry of water into the housing from outside can be prevented, in addition to which the characteristics of sound transmitted through the membrane can be kept even when the membrane has a reduced effective area.