EP4645901A1

EP4645901A1 - Improved vent assembly

Info

Publication number: EP4645901A1
Application number: EP24222212.3A
Authority: EP
Inventors: Zachary Lampert; Theresa Tonge; Rei Chisoku
Original assignee: WL Gore and Associates GK; WL Gore and Associates Inc
Current assignee: WL Gore and Associates GK; WL Gore and Associates Inc
Priority date: 2024-04-29
Filing date: 2024-12-20
Publication date: 2025-11-05

Abstract

There is described a vent assembly comprising an acoustic membrane and an adhesive layer provided on a first side of the acoustic membrane, the adhesive layer having a surface area, the adhesive layer comprising an adhesive wall and the adhesive wall defining a venting aperture through which an active area of the acoustic membrane is exposed, wherein the ratio of the surface area of the adhesive layer to the surface area of the active area of the acoustic membrane is less than 2.0.

Description

Field

The present disclosure relates to the field of vent assemblies, specifically to the field of acoustic vent assemblies and electronic devices comprising the same.

Background

Electronic devices that comprise acoustic transducers such as speakers and microphones often comprise vents or vent assemblies that protect such acoustic transducers from the contact with contaminants such as particulates or liquids. Such vents or vent assemblies typically occlude an aperture in the housing of the electronic device through which sound travels from or to the speaker or microphone respectively.
The materials used to make up the vents or vent assemblies are required to be resistant to the passage of particulates and liquids, especially liquid water, whilst also maximising the transmission of sound through them.
Typically, in order to ensure that the interior of the electronic device is adequately protected from particulates and liquids, the membrane of the vent or vent assembly is tailored to prevent ingress of particulates and liquids whilst trying to minimise the impact of the membrane on the acoustic properties of the vent assembly.
However, the acoustic properties of new electronic devices are required to constantly be improving by the expectations of customers whilst also ensuring that these electronic devices become more durable and resistant to damage due to ingress of liquids and particulates.
Accordingly, there remains a need for improved vents and vent assemblies that have improved acoustic performance.
The present disclosure is intended at least in part to address at least one of these issues.

Summary

According to a first aspect there is provided a vent assembly comprising an acoustic membrane and an adhesive layer provided on a first side of the acoustic membrane, the adhesive layer having a surface area, the adhesive layer comprising an adhesive wall and the adhesive wall defining a venting aperture through which an active area of the acoustic membrane is exposed, wherein the ratio of the surface area of the adhesive layer to the surface area of the active area of the acoustic membrane is less than 2.0.
The ratio of the surface area of the adhesive layer to the surface area of the active area of the acoustic membrane is an area ratio and is referred to herein as the "Area ratio".
The ratio of the surface area of the adhesive layer to the surface area of the active area of the acoustic membrane may be less than 1.9. The ratio of the surface area of the adhesive layer to the surface area of the active area of the acoustic membrane may be less than 1.8. The ratio of the surface area of the adhesive layer to the surface area of the active area of the acoustic membrane may be less than 1.7. The ratio of the surface area of the adhesive layer to the surface area of the active area of the acoustic membrane may be less than 1.6. The ratio of the surface area of the adhesive layer to the surface area of the active area of the acoustic membrane may be less than 1.5.
The ratio of the surface area of the adhesive layer to the surface area of the active area of the acoustic membrane may be from 0.5 to 1.9. The ratio of the surface area of the adhesive layer to the surface area of the active area of the acoustic membrane may be from 0.5 to 1.8. The ratio of the surface area of the adhesive layer to the surface area of the active area of the acoustic membrane may be from 0.5 to 1.7. The ratio of the surface area of the adhesive layer to the surface area of the active area of the acoustic membrane may be from 0.5 to 1.6. The ratio of the surface area of the adhesive layer to the surface area of the active area of the acoustic membrane may be from 0.7 to 1.9. The ratio of the surface area of the adhesive layer to the surface area of the active area of the acoustic membrane may be from 0.9 to 1.9. The ratio of the surface area of the adhesive layer to the surface area of the active area of the acoustic membrane may be from 1.0 to 1.9. The ratio of the surface area of the adhesive layer to the surface area of the active area of the acoustic membrane may be from 1.2 to 1.9.
The ratio of the surface area of the adhesive layer to the surface area of the active area of the acoustic membrane may be from 1.0 to 1.6. The ratio of the surface area of the adhesive layer to the surface area of the active area of the acoustic membrane may be from 1.2 to 1.5.
It will be understood that the acoustic membrane is a membrane that is configured to efficiently transmit acoustic energy across it as measured by insertion loss in decibels (dB) using the method described herein. Typically, the acoustic membrane is a reactive membrane or a substantially reactive membrane or at least a partially reactive membrane that transmits at least a portion of incident acoustic energy by vibrating. Accordingly, the acoustic membrane may at least partially resist the flow of gas through the membrane such that the impact of acoustic energy imparted by gas molecules to the acoustic membrane causes the acoustic membrane to vibrate.
The vent assembly may have any regular or irregular shape. The vent assembly may have a circular, elliptical or oval shape. The vent assembly may have triangular, rectangular, square, oblong, trapezoidal, pentagonal, hexagonal or higher order geometric shape.
The active area of the acoustic membrane may have any regular or irregular shape. The active area of the acoustic membrane may have a circular, elliptical or oval shape. The active area of the acoustic membrane may have a triangular, rectangular, square, oblong, trapezoidal, pentagonal, hexagonal, or higher order geometric shape.
The venting aperture may have any regular or irregular shape. The venting aperture may have a circular, elliptical or oval shape. The venting aperture may have a triangular, rectangular, square, oblong, trapezoidal, pentagonal, hexagonal, or higher order geometric shape.
The acoustic membrane may have a flow resistance of at least 1000 Pa s/m. The acoustic membrane may have a flow resistance of at least 3000 Pa s/m. The acoustic membrane may have a flow resistance of at least 5000 Pa s/m. The acoustic membrane may have a flow resistance from 1000 to 1 × 10¹² Pa s/m.
The acoustic membrane may have a Young's modulus of at least 10 MPa. The acoustic membrane may have a Young's modulus of at least 50 MPa. The acoustic membrane may have a Young's modulus of at least 100 MPa. The acoustic membrane may have a Young's modulus of at least 500 MPa. The acoustic membrane may have a Young's modulus of at least 1000 MPa.
In some embodiments the acoustic membrane has a Young's modulus of from 10 MPa to 5000 MPa. The acoustic membrane may have a Young's modulus of from 50 MPa to 5000 MPa. The acoustic membrane may have a Young's modulus of from 100 MPa to 5000 MPa. The acoustic membrane may have a Young's modulus of from 500 MPa to 5000 MPa. The acoustic membrane may have a Young's modulus of from 1000 MPa to 5000 MPa.
The acoustic membrane may have a flow resistance of at least 1000 Pa s/m and a Young's modulus of at least 50 MPa.
The acoustic membrane may have a thickness of less than 100 µm. The acoustic membrane may have a thickness of less than 75 µm. The acoustic membrane may have a thickness of less than 50 µm.
The acoustic membrane may have a thickness of from 0.1 µm to 90 µm. The acoustic membrane may have a thickness of from 0.1 µm to 75 µm. The acoustic membrane may have a thickness of from 0.1 µm to 50 µm.
The acoustic membrane may have a phase angle having a magnitude greater than 10 degrees as measured at 1 kHz using the method described herein. The acoustic membrane may have a phase angle having a magnitude greater than 20 degrees as measured at 1 kHz using the method described herein. The phase angle is the arctan of the ratio of resistive impedance to reactive impedance (i.e. phase angle = arctan (reactive impedance/resistive impedance). The reactive impedance corresponds to the imaginary part of the complex transfer impedance and the resistive impedance corresponds to the real part of the complex transfer impedance. An acoustic membrane having a phase angle of 0 degrees transmits acoustic energy exclusively through the pores of the material of the acoustic membrane and is a resistive acoustic membrane. An acoustic membrane having a phase angle of +/- 90 degrees transmits acoustic energy exclusively by vibration of the membrane itself. For the avoidance of doubt, the magnitude of the phase angle is indicative of the acoustic characteristics of the acoustic membrane. Therefore, the acoustic characteristics of an acoustic membrane with a phase angle of 20 degrees are the same as an acoustic membrane with a phase angle of -20 degrees.
The acoustic membrane may have a phase angle having a magnitude greater than 30 degrees as measured at 1 kHz using the method described herein. The acoustic membrane may have a phase angle having a magnitude greater than 45 degrees as measured at 1 kHz using the method described herein. The acoustic membrane may have a phase angle having a magnitude greater than 60 degrees as measured at 1 kHz using the method described herein.
The acoustic membrane may have a phase angle having a magnitude from 10 degrees to 90 degrees as measured at 1 kHz using the method described herein. The acoustic membrane may have a phase angle having a magnitude from 20 degrees to 90 degrees as measured at 1 kHz using the method described herein. The acoustic membrane may have a phase angle having a magnitude from 30 degrees to 90 degrees as measured at 1 kHz using the method described herein. The acoustic membrane may have a phase angle having a magnitude from 45 degrees to 90 degrees as measured at 1 kHz using the method described herein. The acoustic membrane may have a phase angle having a magnitude from 60 degrees to 90 degrees as measured at 1 kHz using the method described herein.
The acoustic membrane may comprise a non-porous material. Accordingly, the acoustic membrane may prevent or substantially prevent the flow of air through the acoustic membrane and transmit sound solely by vibration of the acoustic membrane. The acoustic membrane may comprise a non-porous material that is configured to allow gas transfer through the acoustic membrane via a solution diffusion mechanism, for example.
The acoustic membrane may comprise a porous material. The acoustic membrane may transmit sound by vibration of the acoustic membrane and by vibration of gas molecules passing through the pores of the acoustic membrane. The acoustic membrane may be sufficiently porous to allow the flow of gas through the acoustic membrane. Accordingly, the acoustic membrane may be configured to allow gas flow through the acoustic membrane.
The acoustic membrane may be configured to allow the flow of gas through the acoustic membrane. The acoustic membrane may be configured to allow diffusion of gas through the acoustic membrane. The acoustic membrane may comprise pores that allow gas to diffuse through the acoustic membrane. The pores may be sized such that they allow gas to diffuse through the acoustic membrane but are sufficiently small to prevent a flow of gas through the acoustic membrane. The acoustic membrane may be structured such that the gas must take an indirect route through the acoustic membrane.
The acoustic membrane may be impermeable to liquid. Accordingly, the acoustic membrane may allow the passage of gas through the acoustic membrane and not allow the passage of liquid through the acoustic membrane or not allow the passage of gas or liquid through the acoustic membrane.
The acoustic membrane may comprise a fluoropolymer selected from the group: polytetrafluoroethylene (PTFE), perfluoroalkoxy alkane (PFA), polyvinylfluoride (PVF), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), or polyethylenetetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), ethylene fluorinated ethylene propylene (EFEP), or co-polymers or combinations thereof.
The fluoropolymer may be selected from the group: PTFE, PFA and FEP.
The acoustic membrane may comprise a non-fluoropolymer selected from the group: polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyurethane (PU), or co-polymers or combinations thereof.
The acoustic membrane may comprise a polymer selected from the group: PTFE, PFA, PVF, PVDF, PCTFE, or ETFE, FEP, EFEP, PE, PP, PET, PU or co-polymers or combinations thereof.
The acoustic membrane may comprise a polymer selected from the group: PTFE, PE, PU, PET or PP. The acoustic membrane may comprise PTFE, PE, or PU or combinations or co-polymers thereof. The acoustic membrane may comprise PTFE, PE, or combinations or co-polymers thereof.
The acoustic membrane may comprise PTFE or co-polymers thereof.
The acoustic membrane may comprise PE or co-polymers thereof.
The acoustic membrane may comprise PU or co-polymers thereof.
The acoustic membrane may comprise PET or co-polymers thereof.
The acoustic membrane may comprise PP or co-polymers thereof.
The acoustic membrane may comprise an expanded polymer. The expanded polymer may be selected from the group consisting of expanded PE (ePE), expanded PP (ePP), expanded PET (ePET), or an expanded fluoropolymer such as expanded PTFE (ePTFE) or expanded FEP (eFEP).
An expanded polymer may have an increased porosity when compared to the corresponding non-expanded polymer.
As used herein, the term "expanded polymer" refers to a polymer material that has been mechanically expanded at an elevated temperature. For example, the polymer material may be mechanically expanded below the melt temperature of the polymer.
The acoustic membrane may comprise a dense polymer. The dense polymer may be selected from the group consisting of dense PE, dense PP, dense PET, or dense fluoropolymer such as dense PTFE, dense PCTFE, dense ETFE, dense PFA or dense FEP.
As used herein, the term "dense polymer" refers to a polymer material that is substantially non-porous. Accordingly, the dense polymer may have a non-measurable airflow using the test method described herein.
The acoustic membrane may comprise a densified expanded polymer. The densified expanded polymer may be selected from the group consisting of densified ePE, densified ePP, densified ePET, or densified expanded fluoropolymer such as densified ePTFE or densified eFEP.
The term "densified expanded polymer" as used herein refers to an expanded polymer that has been densified after the material has been expanded.
A densified expanded polymer may have the microstructure of an expanded polymer and a lower porosity than the expanded polymer. For example, the densified expanded polymer may have the node and fibril structure of the expanded porosity but have a reduced porosity.
In some embodiments the acoustic membrane may comprise a plurality of layers. For example, the acoustic membrane may comprise a laminate.
The adhesive layer may comprise an acrylic adhesive, or a silicone adhesive.
The adhesive layer may comprise a heat activated adhesive, a pressure adhesive, or an ultraviolet curable adhesive.
The adhesive layer may comprise a carrier substrate having a first major surface and a second major surface and an adhesive may be provided on the first major surface and the second major surface.
The adhesive wall may have a substantially uniform width. Accordingly, the width of adhesive in the adhesive wall defining the venting aperture may be substantially the same around the entire venting aperture. In embodiments where the venting aperture has a circular shape the width of the adhesive wall may be substantially the same around the circumference of the venting aperture. In embodiments where the venting aperture has a rectangular shape the width of the adhesive wall may be substantially the same along the width and length of the venting aperture.
In a second aspect there is provided a vent assembly comprising an acoustic membrane and an adhesive layer provided on a first side of the acoustic membrane, the adhesive layer comprising an adhesive wall defining a venting aperture through which an active area of the acoustic membrane is exposed, the vent assembly having a width comprising a width of the active area of the acoustic membrane and a width of the adhesive wall either side the venting aperture, wherein the ratio of the sum of the widths of the adhesive wall either side of the venting aperture to the width of the active area of the acoustic membrane is less than 1.0.
The ratio of the sum of the widths of the adhesive wall either side of the venting aperture to the width of the active area of the acoustic membrane is a width ratio and is referred to herein as the "Width Ratio".
The ratio of the sum of the widths of the adhesive wall either side of the venting aperture to the width of the active area of the acoustic membrane may be less than 0.9. The ratio of the sum of the widths of the adhesive wall either side of the venting aperture to the width of the active area of the acoustic membrane may be less than 0.8. The ratio of the sum of the widths of the adhesive wall either side of the venting aperture to the width of the active area of the acoustic membrane may be less than 0.7. The ratio of the sum of the widths of the adhesive wall either side of the venting aperture to the width of the active area of the acoustic membrane may be less than 0.6.
The ratio of the sum of the widths of the adhesive wall either side of the venting aperture to the width of the active area of the membrane may be from 0.1 to 0.9. The ratio of the sum of the widths of the adhesive wall either side of the venting aperture to the width of the active area of the membrane may be from 0.1 to 0.8. The ratio of the sum of the widths of the adhesive wall either side of the venting aperture to the width of the active area of the membrane may be from 0.1 to 0.7. The ratio of the sum of the widths of the adhesive wall either side of the venting aperture to the width of the active area of the membrane may be from 0.1 to 0.6.
The vent assembly may have any regular or irregular shape. The vent assembly may have a circular, elliptical or oval shape. The vent assembly may have triangular, rectangular, square, oblong, trapezoidal, pentagonal, hexagonal or higher order geometric shape.
The active area of the acoustic membrane may have any regular or irregular shape. The active area of the acoustic membrane may have a circular, elliptical or oval shape. The active area of the acoustic membrane may have a triangular, rectangular, square, oblong, trapezoidal, pentagonal, hexagonal, or higher order geometric shape.
The venting aperture may have any regular or irregular shape. The venting aperture may have a circular, elliptical or oval shape. The venting aperture may have a triangular, rectangular, square, oblong, trapezoidal, pentagonal, hexagonal, or higher order geometric shape.
Typically, the width used to define the width ratio passes through a middle portion of the vent assembly. The width used to define the width ratio may pass through the centre of the vent assembly. The width used to define the width ratio may pass through the centre of the acoustic membrane. In embodiments where the vent assembly has a circular shape, the width may correspond to the diameter of the vent assembly. In embodiments where the vent assembly has a rectangular shape, the width may correspond to the minor dimension of the rectangular shape.
The width used to define the width ratio may pass through the centre of the vent assembly. The width used to define the width ratio may pass through the centre of the active area of the acoustic membrane.
As per the first aspect, it will be understood that the acoustic membrane is a membrane that is configured to efficiently transmit acoustic energy across it as measured by insertion loss in decibels (dB) using the method described herein. Typically, the acoustic membrane is a reactive membrane or a substantially reactive membrane or at least a partially reactive membrane that transmits at least a portion of acoustic energy by vibrating. Accordingly, the acoustic membrane may at least partially resist the flow of gas through the membrane such that the impact of acoustic energy imparted by gas molecules to the acoustic membrane causes the acoustic membrane to vibrate.
The acoustic membrane may have a flow resistance of at least 1000 Pa s/m. The acoustic membrane may have a flow resistance of at least 3000 Pa s/m. The acoustic membrane may have a flow resistance of at least 5000 Pa s/m. The acoustic membrane may have a flow resistance of from 1000 to 1 × 10¹² Pa s/m.
The acoustic membrane may have a Young's modulus of at least 10 MPa. The acoustic membrane may have a Young's modulus of at least 50 MPa. The acoustic membrane may have a Young's modulus of at least 100 MPa. The acoustic membrane may have a Young's modulus of at least 500 MPa. The acoustic membrane may have a Young's modulus of at least 1000 MPa.
The acoustic membrane may have a Young's modulus of from 10 MPa to 5000 MPa. The acoustic membrane may have a Young's modulus of from 50 MPa to 5000 MPa. The acoustic membrane may have a Young's modulus of from 100 MPa to 5000 MPa. The acoustic membrane may have a Young's modulus of from 500 MPa to 5000 MPa. The acoustic membrane may have a Young's modulus of from 1000 MPa to 5000 MPa.
The acoustic membrane may have a flow resistance of at least 1000 Pa s/m and a Young's modulus of at least 50 MPa.
The acoustic membrane may have a thickness of less than 100 µm. The acoustic membrane may have a thickness of less than 75 µm. The acoustic membrane may have a thickness of less than 50 µm.
The acoustic membrane may have a thickness of from 1 µm to 90 µm. The acoustic membrane may have a thickness of from 1 µm to 75 µm. The acoustic membrane may have a thickness of from 1 µm to 50 µm.
The acoustic membrane may have a phase angle having a magnitude greater than 10 degrees as measured at 1 kHz using the method described herein. The acoustic membrane may have a phase angle having a magnitude greater than 20 degrees as measured at 1 kHz using the method described herein. The phase angle is the arctan of the ratio of reactive impedance to resistive impedance (i.e. phase angle = arctan (reactive impedance/resistive impedance). The reactive impedance corresponds to the imaginary part of the complex transfer impedance and the resistive impedance corresponds to the real part of the complex transfer impedance. An acoustic membrane having a phase angle of 0 degrees transmits acoustic energy exclusively through the pores of the material of the acoustic membrane and is a resistive acoustic membrane. An acoustic membrane having a phase angle of +/- 90 degrees transmits acoustic energy exclusively by vibration of the membrane itself. For the avoidance of doubt, the magnitude of the phase angle is indicative of the acoustic characteristics of the acoustic membrane. Therefore, the acoustic characteristics of an acoustic membrane with a phase angle of 20 degrees are the same as an acoustic membrane with a phase angle of -20 degrees.
The acoustic membrane may have a phase angle having a magnitude greater than 30 degrees as measured at 1 kHz using the method described herein. The acoustic membrane may have a phase angle having a magnitude greater than 45 degrees as measured at 1 kHz using the method described herein. The acoustic membrane may have a phase angle having a magnitude greater than 60 degrees as measured at 1 kHz using the method described herein.
The acoustic membrane may have a phase angle having a magnitude from 10 degrees to 90 degrees as measured at 1 kHz using the method described herein. The acoustic membrane may have a phase angle having a magnitude from 20 degrees to 90 degrees as measured at 1 kHz using the method described herein. The acoustic membrane may have a phase angle having a magnitude from 30 degrees to 90 degrees as measured at 1 kHz using the method described herein. The acoustic membrane may have a phase angle having a magnitude from 45 degrees to 90 degrees as measured at 1 kHz using the method described herein. The acoustic membrane may have a phase angle having a magnitude from 60 degrees to 90 degrees as measured at 1 kHz using the method described herein.
The acoustic membrane may comprise a non-porous material. Accordingly, the acoustic membrane may prevent or substantially prevent the flow of air through the acoustic membrane and transmit sound solely by vibration of the acoustic membrane. The acoustic membrane may comprise a non-porous material that is configured to allow gas transfer through the acoustic membrane via a solution diffusion mechanism, for example.
The acoustic membrane may comprise a porous material. The acoustic membrane may transmit sound by vibration of the acoustic membrane and by vibration of gas molecules passing through the pores of the acoustic membrane. The acoustic membrane may be sufficiently porous to allow the flow of gas through the acoustic membrane. Accordingly, the acoustic membrane may be configured to allow gas flow through the acoustic membrane.
The acoustic membrane may be configured to allow the flow of gas through the acoustic membrane. The acoustic membrane may be configured to allow diffusion of gas through the acoustic membrane. The acoustic membrane may comprise pores that allow gas to diffuse through the acoustic membrane. The pores may be sized such that they allow gas to diffuse through the acoustic membrane but are sufficiently small to prevent a flow of gas through the acoustic membrane. The acoustic membrane may be structured such that the gas must take an indirect route through the acoustic membrane.
The acoustic membrane may be impermeable to liquid. Accordingly, the acoustic membrane may allow the passage of gas through the acoustic membrane and not allow the passage of liquid through the acoustic membrane.
The acoustic membrane may comprise a fluoropolymer selected from the group: polytetrafluoroethylene (PTFE), perfluoroalkoxy alkane (PFA), polyvinylfluoride (PVF), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), or polyethylenetetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), ethylene fluorinated ethylene propylene (EFEP), or co-polymers or combinations thereof.
The fluoropolymer may be selected from the group: PTFE, PFA and FEP.
The acoustic membrane may comprise a non-fluoropolymer selected from the group: polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyurethane (PU), or co-polymers or combinations thereof.
The acoustic membrane may comprise a polymer selected from the group: PTFE, PFA, PVF, PVDF, PCTFE, or ETFE, FEP, EFEP, PE, PP, PET, PU or co-polymers or combinations thereof.
The acoustic membrane may comprise a polymer selected from the group: PTFE, PE, PU, PET or PP. The acoustic membrane may comprise PTFE, PE, or PU or combinations or co-polymers thereof. The acoustic membrane may comprise PTFE, PE, or combinations or co-polymers thereof.
The acoustic membrane may comprise PTFE or co-polymers thereof.
The acoustic membrane may comprise PE or co-polymers thereof.
The acoustic membrane may comprise PU or co-polymers thereof.
The acoustic membrane may comprise PET or co-polymers thereof.
The acoustic membrane may comprise PP or co-polymers thereof.
The acoustic membrane may comprise an expanded polymer. The expanded polymer may be selected from the group consisting of expanded PE (ePE), expanded PP (ePP), expanded PET (ePET), or an expanded fluoropolymer such as expanded PTFE (ePTFE) or expanded FEP (eFEP).
An expanded polymer may have an increased porosity when compared to the corresponding non-expanded polymer.
As used herein, the term "expanded polymer" refers to a polymer material that has been mechanically expanded at an elevated temperature. For example, the polymer material may be mechanically expanded below the melt temperature of the polymer.
The acoustic membrane may comprise an electrospun polymer. Accordingly, the acoustic membrane, or a component of the acoustic membrane, may be formed by electrospinning methods such as those known in the art, for example.
The acoustic membrane may comprise a dense polymer. The dense polymer may be selected from the group consisting of dense PE, dense PP, dense PET, or dense fluoropolymer such as dense PTFE, dense PCTFE, dense ETFE, dense PFA or dense FEP.
As used herein, the term "dense polymer" refers to a polymer material that is substantially non-porous. Accordingly, the dense polymer may have a non-measurable airflow using the test method described herein.
The acoustic membrane may comprise a densified expanded polymer. The densified expanded polymer may be selected from the group consisting of densified ePE, densified ePP, densified ePET, or densified expanded fluoropolymer such as densified ePTFE or densified eFEP.
The term "densified expanded polymer" as used herein refers to an expanded polymer that has been densified after the material has been expanded.
A densified expanded polymer may have the microstructure of an expanded polymer and a lower porosity than the expanded polymer. For example, the densified expanded polymer may have the node and fibril structure of the expanded porosity but have a reduced porosity.
In some embodiments the acoustic membrane may comprise a plurality of layers. For example, the acoustic membrane may comprise a laminate.
The adhesive layer may comprise an acrylic adhesive, or a silicone adhesive.
The adhesive layer may comprise a heat activated adhesive, a pressure adhesive, or an ultraviolet curable adhesive.
The adhesive layer may comprise a carrier substrate having a first major surface and a second major surface and adhesive is provided on the first major surface and the second major surface.
The adhesive wall may have a substantially uniform width. Accordingly, the width of adhesive in the adhesive wall defining the venting aperture may be substantially the same around the entire venting aperture. In embodiments where the venting aperture has a circular cross section the width of the adhesive wall may be substantially the same around the circumference of the venting aperture. In embodiments where the venting aperture has a rectangular cross section the width of the adhesive wall may substantially the same along the width and length of the venting aperture.
According to a third aspect there is provided an electronic device comprising a housing and an acoustic transducer, the housing defining an acoustic aperture and a vent assembly of the first aspect or of the second aspect occluding the acoustic aperture such that the adhesive layer adheres the vent assembly to the housing around the acoustic aperture, wherein the acoustic transducer is positioned adjacent to the acoustic aperture.
The acoustic transducer may be a speaker or a microphone.
The vent assembly is typically configured to prevent the ingress of contaminants such as liquid water and particulates into the housing through the acoustic aperture whilst allowing efficient transmission of acoustic energy to and from the acoustic transducer through the acoustic membrane of the vent assembly and through the acoustic aperture.
The electronic device may comprise a first acoustic transducer and a second acoustic transducer. The first acoustic transducer may be positioned adjacent to the acoustic aperture. The housing may define a first acoustic aperture and a second acoustic aperture and the first acoustic transducer may be positioned adjacent to the first acoustic aperture and the second transducer may be positioned adjacent to the second acoustic aperture. A first vent assembly according to the first aspect or the second aspect may be adhered over the first acoustic aperture. A second vent assembly according to the first aspect or the second aspect may be adhered over the second acoustic aperture. Accordingly, the first acoustic transducer and the second acoustic transducer are protected from contaminants by the first vent assembly and the second vent assembly respectively.

Brief Description of the Figures

Embodiments of the present invention will now be described, by way of non-limiting example, with reference to the accompanying drawings.

Figure 1 : A schematic bottom-up view of a vent assembly;
Figure 2 : A schematic bottom-up view of a vent assembly according to an embodiment;
Figure 3 : A schematic side view of a housing of an electronic device according to an embodiment;
Figure 4 : A schematic bottom-up view of a vent assembly;
Figure 5 : A schematic bottom-up view of a vent assembly according to an embodiment;
Figure 6 : A schematic side view of a test apparatus for measuring phase angle for a vent assembly;
Figure 7 : A plot of Insertion Loss (IL) as a function of frequency for a vent assembly comprising an expanded polyethylene acoustic membrane (M5) and an acrylic adhesive layer (A7) defining a circular venting aperture;
Figure 8 : A plot of Insertion Loss (IL) as a function of frequency for a vent assembly comprising an expanded polyethylene acoustic membrane (M5) and an acrylic adhesive layer (A7) with a square venting aperture;
Figure 9 : A plot of Insertion Loss (IL) as a function of frequency for a vent assembly comprising an expanded polyethylene acoustic membrane (M6) and an acrylic adhesive layer (A7) with a circular venting aperture;
Figure 10 : A plot of Insertion Loss (IL) as a function of frequency for a vent assembly comprising an expanded polyethylene acoustic membrane (M6) and an acrylic adhesive layer (A7) with a square venting aperture;
Figure 11 : A plot of Insertion Loss (IL) as a function of frequency for a vent assembly comprising an expanded polyethylene acoustic membrane (M5) and an acrylic/silicone adhesive layer (A4) with a circular venting aperture after heating at 70°C for 30 minutes;
Figure 12 : A plot of Insertion Loss (IL) as a function of frequency for a vent assembly comprising an expanded polyethylene acoustic membrane (M5) and an acrylic/silicone adhesive layer (A4) with a square venting aperture after heating at 70°C for 30 minutes;
Figure 13 : A plot of Insertion Loss (IL) as a function of frequency for a vent assembly comprising a dense polyethylene acoustic membrane (M3) and an acrylic adhesive layer (A7) with a circular venting aperture;
Figure 14 : A plot of Insertion Loss (IL) as a function of frequency for a vent assembly comprising a dense polyethylene acoustic membrane (M3) and an acrylic adhesive layer (A7) with a square venting aperture;
Figure 15 : A plot of Insertion Loss (IL) as a function of frequency for a vent assembly comprising a polyurethane acoustic membrane (M9) and a UV curable adhesive layer (A10) with a circular venting aperture;
Figure 16 : A plot of Insertion Loss (IL) as a function of frequency for a vent assembly comprising a polyurethane acoustic membrane (M9) and an acrylic adhesive layer (A1) with a circular venting aperture;
Figure 17 : A plot of Insertion Loss (IL) as a function of frequency for a vent assembly comprising a polyurethane acoustic membrane (M9) and an acrylic adhesive layer (A2) with a square venting aperture;
Figure 18 : A plot of Insertion Loss (IL) as a function of frequency for a vent assembly comprising an expanded polytetrafluoroethylene (ePTFE) acoustic membrane (M2) and an acrylic adhesive layer (A1) with a circular venting aperture; and
Figure 19 : A plot of Insertion Loss (IL) as a function of frequency for a vent assembly comprising an ePTFE acoustic membrane (M2) and a phenolic resin/nitrile rubber heat activated film adhesive layer (A9) with a square venting aperture.

Detailed Description

While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention and do not delimit the scope of the invention.
To facilitate the understanding of this invention, a number of terms are defined below. Terms defined herein have meanings as commonly understood by a person of ordinary skill in the areas relevant to the present invention. Terms such as "a", "an" and "the" are not intended to refer to only a singular entity, but include the general class of which a specific example may be used for illustration. The terminology herein is used to describe specific embodiments of the invention, but their usage does not delimit the invention, except as outlined in the claims.

Test Methods

Phase Angle Testing

Phase angle testing was performed by the Impedance Tube Transfer Matrix Test ("ITTMT"), which is a modified version of ASTM-E2611-09- the standard test method for measuring normal incidence impedance and phase based on the 4 microphone transfer matrix method. All modifications to ASTM-E2611-09 are set forth herein. An exemplary test set-up is shown in Figure 6. The transfer matrix of the assembly was measured and we use T12 element of the transfer matrix as the acoustic impedance value for all the assemblies described in the examples. An impedance tube was used to make measurements across a frequency range of 500 Hz to 20,000 Hz. The inner diameter of the tube was 8 mm. The impedance tube was designed in accordance with ASTM E1050-12 and ASTM E2611-09. A JBL 2426H compression driver was mounted at one end of the tube and powered by a Bruel and Kjaer Type 2735 amplifier connected to a 31-band ART 351 graphic equalizer. The measurement system used 4 Bruel and Kjaer Type 4138 microphones connected to a 4 channel Bruel and Kjaer Type 3160-A-042 LAN-XI Frontend with a generator output. Data was acquired and processed using Bruel and Kjaer PULSE Labshop with Type 7758 Acoustic Material Testing Software, version 21.
The sample assemblies that were tested had an inner diameter of 1.6mm (circular active area) or side length of 1.42 mm (square active area), which was smaller than the inner diameter of the impedance tube. A pair of conical adapters was therefore required in order to mount the sample assemblies. The convergent cone had an inlet diameter of 8 mm and an outlet diameter of 1.5 mm. The divergent cone had an inlet diameter of 1.5 mm and an outlet diameter of 8 mm. When using conical adapters, additional processing of the data was required to account for the converging geometry of the cones. Theoretical equations were derived to calculate the transfer matrices of the conical adapters and can be found in the literature (Hua, X. and Herrin, D., "Practical Considerations when using the Two-Load Method to Determine the Transmission Loss of Mufflers and Silencers," SAE Int. J. Passeng. Cars - Mech. Syst. 6(2):1094-1101, 2013 & Mechel, F. P. (2008). Formulas of Acoustics. New York, NY: Springer).

Insertion Loss

The general method used to measure insertion loss was as per the apparatus and method as described below and in Example 1 of WO 2018/140705 in the name of W. L. Gore & Associates, Inc., which is incorporated herein by reference in its entirety.
An acoustic testing apparatus was configured with a testing system in an "open" condition, wherein the 28 available sample locations (and four reference ports) were left uncovered. The testing apparatus was closed to seal the acoustic chamber, and the system was operated through a frequency range of 100 Hz to 20 kHz at amplitude of 94 dB SPL (referenced to 20 Pa). The acoustic insertion loss across the acoustic cavity and respective ports in the sample holders was measured across the frequency range. Equation A Insertion loss, IL = [dB SPL of Open Condition (no vent assembly present)] - [dB SPL of Vent Assembly (vent assembly present)]

Flow resistance

Airflow was measured using an ATEQ D520 Airflow Tester. In all configurations, the active area was assumed to be 2.99 cm² and the membranes were tested using a pressure difference of 12 mbar. The measured airflow in units of L/hr was converted to flow resistance (Pa*s/m) as per the equation below $\begin{array}{l} Flow Resistance \\ = \frac{(Pressure for Airflow measurement) [mbar] \times (Measurement Area) [{cm}^{2}]}{(ATEQ value) [\frac{L}{hr}]} \\ = \frac{(12 \times 100) [Pa] \times (2.99 \times 10^{- 4}) [m^{2}]}{ATEQ value \times 2.77778 \times 10^{- 7} [\frac{m^{3}}{s}]} = \frac{1291680}{ATEQ} \end{array}$ where, pressure of airflow measurement is 12 mbar and measurement area is 2.99 cm².

Thickness

Thicknesses of the polymer membranes were measured herein using a commercially available Keyence LS-7010 M.

Youngs Modulus

Herein, Young's moduli of the polymer membranes were measured in accordance with ISO 527-1:2012.

Adhesive-to-Membrane Area Ratio & Line Length Ratio

A commercially available Keyence VHX-5000 optical microscope was used to image the vent assemblies. Images were then opened in the accompanying analysis portion of the software and profile lines were applied to measure the total adhesive area, the total membrane area, the adhesive wall width and width of the active area formed by the membrane. The adhesive to membrane width ratio was calculated as, $\begin{array}{l} Adhesive to Membrane Width Ratio \\ = \frac{Sum of the widths of adhesive wall either side of vent aperture}{Width of vent aperture formed by active area of membrane} \end{array}$
The adhesive-to-membrane area ratio was calculated as, $Adhesive to Membrane Area Ratio = \frac{Total Area of Adhesive Wall}{Total Area of Membrane}$

General Examples

Examples 1 and 2 below describe general examples of vent assemblies according to the disclosure with reference to Figures 2, 3 and 5 and typical vent assemblies with reference to Figures 1 and 4.

Example 1

Typically, a vent assembly 1 (see Figure 1) comprises an acoustic membrane 2 and an adhesive layer 4 where the adhesive layer 4 comprises an adhesive wall 6 that defines a venting aperture 8 through which an active area 10 of the acoustic membrane 2 is exposed. Figure 1 shows a circular vent assembly 1 and the active area 10 has a diameter 12 that corresponds to a width of the active area 10 and the adhesive wall 6 of the adhesive layer 4 has a width 14.
An example vent assembly 20 is shown in Figure 2. The vent assembly 20 comprises an acoustic membrane 22 and an adhesive layer 24. The adhesive layer 24 comprises an adhesive wall 26 defining a venting aperture 28 through which an active area 30 of the acoustic membrane 22 is exposed. The vent assembly 20 is circular and the active area 30 of the acoustic membrane 22 has the same diameter 32 as the active area 10 of the vent assembly 1 described above. However, the width 34 of the adhesive wall 26 is thinner than the adhesive wall 6.
Figure 3 shows the example vent assembly 20 installed across an acoustic aperture 36 defined in the housing 38 of an electronic device 40. The adhesive layer 24 adheres the vent assembly 20 over the acoustic aperture 34 and a microphone 42 (acting as an acoustic transducer) is positioned adjacent to the acoustic aperture 34 and is protected from contaminants by the vent assembly 20.
Example vent assembly 20 is the same as the vent assembly 1 except for the width of the adhesive wall 26.

Example 2

Typically, a vent assembly 50 (see Figure 4) comprises an acoustic membrane 52 and an adhesive layer 54 where the adhesive layer 54 comprises an adhesive wall 56 that defines a venting aperture 58 through which an active area 60 of the acoustic membrane 52 is exposed. Figure 4 shows a rectangular vent assembly 50 and the active area 60 has a width 62 and the adhesive wall 56 of the adhesive layer 54 has a width 64.
An example vent assembly 70 is shown in Figure 5. The vent assembly 70 comprises an acoustic membrane 72 and an adhesive layer 74. The adhesive layer 74 comprises an adhesive wall 76 defining a venting aperture 78 through which an active area 80 of the acoustic membrane 72 is exposed. The vent assembly 70 is rectangular and the active area 80 of the acoustic membrane 72 has the same width 82 as the active area 60 of the vent assembly 50 described above. However, the width 84 of the adhesive wall 76 is thinner than the width of the adhesive wall 56.
Example vent assembly 70 is the same as the vent assembly 50 except for the width of the adhesive wall 76.

Specific Examples

Example vent assemblies were prepared as follows. First, the bottom and top surface of an acoustic membrane (see Table 1 below for membranes used and their properties) was laminated to an adhesive layer (see Table 2 below for list and description of adhesives used) having pre-cut circle and rectangular venting apertures to form a sandwich structure with membrane in the middle and adhesive on the top and bottom from a side view. The adhesive release liner of the bottom most layer of adhesive in the sandwich structure was removed and laminated to an easy release baseliner (ASC50 S3, obtained commercially from Top Tech Substrates Co., Ltd) comprising a 50 µm-thick layer of polyester with a coating of Tesa 7475-V02 acrylic adhesive. The adhesive release liner of the top most layer of adhesive in the sandwich structure was removed and laminated first to a Lumirror T60 #50 polyester film (obtained commercially from Toray), S5012L pull tab added (obtained commercially from Tailun Electronic Materials (Suzhou) Co., Ltd) and outer dimensions die cut to produce vent assemblies with circular and rectangular shapes having adhesive-to-membrane area ratios and adhesive-to-membrane width ratios as described in Table 3. Prior to testing each vent assembly, the pull tab and the base liner were removed and the vent assembly installed on the testing apparatus as described in the test methods above.

Acoustic membranes used in the following examples were as follows:

Table 1: Membranes used in vent assembly examples and properties of those membranes.

	Material	Thickness (µm)	Flow resistance (Pa.s/m)	Young's Modulus (MPa)	Phase angle (degrees)
M1	ePTFE	9.4	7.77 × 10³	61	59.93
M2	ePTFE	15	9.36 × 10⁴	60	73.71
M3	PE	1.31	1.29 × 10¹¹	3309	80.25
M4	PE	0.72	1.29 × 10¹¹	1372	86.03
M5	ePE	4.4	1.53 × 10⁵	1084	82.55
M6	ePE	9.6	2.55 × 10⁵	418	80.16
M7	ePE	4.23	3.07 × 10⁵	1363	77.23
M8	ePE	3.28	1.93 × 10⁶	1892	83.70
M9	PU	10	N/A	50	84.91

The membranes described in Table 1 above were made or obtained as described below.

Polytetrafluoroethylene (PTFE) membranes

M1: comprising an expanded polytetrafluoroethylene (ePTFE) membrane obtained from W. L. Gore & Associates, Inc. under part number GAW337, manufactured according to the teachings of US3953566 , which is hereby incorporated-by-reference in its entirety.
M2: Comprising an expanded polytetrafluoroethylene (ePTFE) membrane obtained from W. L. Gore & Associates, Inc. under part number GAW331WH (TPV572) GAW344, manufactured according to the teachings of US 3,953,566 and each of which are hereby incorporated-by-reference in their entirety.

Polyethylene (PE) Membranes

The polyethylene membrane is formed from a polyethylene polymer comprising ultrahigh molecular weight polyethylene. For the avoidance of doubt, in the context of the present disclosure, ultrahigh molecular weight polyethylene (UHMWPE) refers to polyethylene having an average molecular weight of about 1,000,000 g/mol to about 10,000,000 g/mol.
Precursor Membrane A : A gel-processed UHMWPE membrane with a mass/area of 3.65 g/m², a bubble point of 139 psi, an airflow of 3.5 L/hr at 12 mbar and 2.99 cm², a thickness of 11.5 microns, a porosity of 66.2%, a specific surface area 45.7 m²/g, a MD MTS of 232 MPa, a TD MTS of 187 MPa, a MD modulus of 442 MPa, and a TD modulus of 419 MPa. The starting resin used to make the membrane had a molecular weight of 4,300,000 g/mol, according to the supplier.
Precursor Membrane B: A gel-processed UHMWPE membrane with a mass/area of 4.1 g/m², a bubble point of 139 psi, a thickness of 11.5 microns, a porosity of 62.0 %, a specific surface area 45.7 m²/g, a MD MTS of 228 MPa, a TD MTS of 174 MPa, a MD modulus of 442 MPa, and a TD modulus of 419 MPa. The starting resin used to make the membrane had a molecular weight of 4,300,000 g/mol, according to the supplier.
M3: The above-described membrane Precursor A was drawn in the longitudinal/machine direction between banks of rolls at a gap distance of 36.3 cm over a heated plate set to a temperature of 128°C at a run speed of 3.3 m/min. The speed ratio between the second bank of rolls and the first bank of rolls, and hence the expansion ratio was 2.0:1.
The longitudinally drawn membrane was then drawn transversely at a temperature of approximately 145°C to a ratio of 7.4:1 at a run speed of 8 m/min at a strain rate of 7.1%/s for a residence time of 1.94 min. This was followed by a temperature treatment at 150°C for a residence time of 0.44 min while restrained. The properties of the resultant membrane are detailed in Table 1. The resultant membrane is non-porous.
M4: The above-described membrane Precursor B was drawn in the longitudinal/machine direction between banks of rolls at a gap distance of 36.3 cm over a heated plate set to a temperature of 128°C at a run speed of 2.4 m/min. The speed ratio between the second bank of rolls and the first bank of rolls, and hence the expansion ratio was 2.4:1.
The longitudinally drawn membrane was then drawn transversely at a temperature of approximately 145°C to a ratio of 11.4:1 at a run speed of 8 m/min at a strain rate of 11.5%/s for a residence time of 1.94 min. This was followed by a temperature treatment at 150°C for a residence time of 0.44 min while restrained. The properties of the resultant membrane are detailed in Table 1. The resultant membrane is non-porous.
M5: A gel-processed ultra-high-molecular-weight polyethylene (UHMWPE) membrane identical to that described above as Precursor A was treated as follows.
The above-described membrane was drawn in the longitudinal/machine direction between banks of rolls at a gap distance of 61 cm over a heated plate set to a temperature of 130°C at a run speed of 3.0 m/min. The speed ratio between the second bank of rolls and the first bank of rolls, and hence the expansion ratio was 1.5:1.
The longitudinally drawn membrane was then heated in an oven for 2.5 min at a temperature of approximately 128°C and drawn transversely at a temperature of approximately 133°C to a ratio of 8:1 at a strain rate of 4.7 %/s for a residence time of 2.5 min. Then, the membrane is held approximately at 133°C for an additional 0.83 min.
The properties of the resultant membrane are detailed in Table 1.
M6: A gel-processed UHMWPE membrane with a mass/area of 2.44 g/m², a bubble point of 148 psi, an airflow of 4.9 L/hr at 12 mbar and 2.99 cm², a thickness of 9.6 microns, a porosity of 68.2%, a specific surface area 62.9 m²/g, a MD MTS of 240 MPa, a TD MTS of 216 MPa, a MD modulus of 453 MPa, and a TD modulus of 386 MPa. The starting resin used to make the membrane had a molecular weight of 4,300,000 g/mol, according to the supplier.
M7: A gel-processed ultra-high-molecular-weight polyethylene (UHMWPE) membrane identical to that described above as Precursor B was treated as follows.
The above-described membrane was drawn in the longitudinal/machine direction between banks of rolls at a gap distance of 61 cm over a heated plate set to a temperature of 129°C at a run speed of 3.0 m/min. The speed ratio between the second bank of rolls and the first bank of rolls, and hence the expansion ratio was 1.5:1.
The longitudinally drawn membrane was then heated in an oven for 1.2 min at a temperature of approximately 130°C and then drawn transversely at a temperature of approximately 135°C to a ratio of 6.2:1 at a strain rate of 7.2 %/s for a residence time of 1.2 min. Then, the membrane is held approximately at 135°C for an additional 0.4 min.
The properties of the resultant membrane are detailed in Table 1.
M8: A gel-processed ultra-high-molecular-weight polyethylene (UHMWPE) membrane identical to that described above as Precursor B was treated as follows.
The above-described membrane was drawn in the longitudinal/machine direction between banks of rolls at a gap distance of 61 cm over a heated plate set to a temperature of 129°C at a run speed of 3.0 m/min. The speed ratio between the second bank of rolls and the first bank of rolls, and hence the expansion ratio was 1.5:1.
The longitudinally drawn membrane was then heated in an oven for 1.2 min at a temperature of approximately 133°C and then drawn transversely at a temperature of approximately 138°C to a ratio of 6.2:1 at a strain rate of 7.2 %/s for a residence time of 1.2 min. Then, the membrane is held approximately at 138°C for an additional 0.4 min.
The properties of the resultant membrane are detailed in Table 1.

Polyurethane (PU) Film

M9: A commercially available thermoplastic non-porous polyurethane film was obtained. It was measured as having a thickness of 10 microns and a Young's modulus of 50 MPa.

Adhesive layers were obtained from commercial suppliers and are shown below in Table 2:

Table 2: Adhesives used in vent assembly examples and properties of the adhesives.

	Supplier Ref:	Adhesive	Carrier	Thickness (µm)
A1	Nitto 5605 BRN	Acrylic	PET	50
A2	Tesa 4972	Acrylic	PET	50
A3	Tesa 68552	Acrylic	PET	50
A4	3M 9119-50	Acrylic/Silicone	PET	50
A5	Tesa 61532	Acrylic/Silicone	PET	50
A6	Tesa 61350	Acrylic	PET	50
A7	Tesa 63305	Monolithic Acrylic	-	50
A8	Tesa 68875	Bio-Acrylic	PET	50
A9	Tesa 58469	Phenolic Resin/Nitrile Rubber Heat Activated Film (HAF) Adhesive	-	10
A10	Advanced Adhesive Technology AC-99005DT	UV Activated Acrylic	PET	50

Example vent assemblies were assembled as described above and tested using the test methods described above and the results are described in Table 3 below.

Table 3: Example vent assemblies showing the effect of area ratio and width ratio on acoustic insertion loss.

#	Membrane	Adhesive	Adhesive wall width (mm)	Area Ratio	Width Ratio	Active area shape	Insertion loss @ 1kHz (dB)
1	M1	A2	1.2	5.25	1.50	Circle	0.42
			0.4	1.25	0.50	Circle	0.37
			1.2	6.24	1.69	Square	0.48
			0.4	1.44	0.56	Square	0.37
2	M1	A3	1.2	5.25	1.50	Circle	0.4
			0.4	1.25	0.50	Circle	0.3
			1.2	6.24	1.69	Square	0.42
			0.4	1.44	0.56	Square	0.35
3	M1	A7	1.2	5.25	1.50	Circle	0.4
			0.4	1.25	0.50	Circle	0.31
			1.2	6.24	1.69	Square	0.43
			0.4	1.44	0.56	Square	0.31
4	M2	A2	1.2	5.25	1.50	Circle	2.25
			0.8	3.00	1.00	Circle	2.14
			0.4	1.25	0.50	Circle	1.38
5	M2	A7	1.2	6.24	1.69	Square	3.31
			0.8	3.52	1.13	Square	2.86
			0.4	1.44	0.56	Square	2.73
6	M2	A9	1.2	6.24	1.69	Square	3.18
			0.8	3.52	1.13	Square	2.71
			0.4	1.44	0.56	Square	2.28
7	M8	A1	1.2	5.25	1.50	Circle	4.81
			0.8	3.00	1.00	Circle	3.91
			0.4	1.25	0.50	Circle	2.48
			1.2	6.24	1.69	Square	5.36
			0.8	3.52	1.13	Square	4.39
			0.4	1.44	0.56	Square	2.72
8	M8	A10	1.2	5.25	1.50	Circle	4.36
			0.4	1.25	0.50	Circle	2.31
9	M5	A1	2.0	11.25	2.50	Circle	4.31
			1.2	5.25	1.50	Circle	4.23
			0.8	3.00	1.00	Circle	3.7
			0.4	1.25	0.50	Circle	2.49
			2.0	13.46	2.82	Square	4.74
			1.2	6.24	1.69	Square	4.65
			0.8	3.52	1.13	Square	3.96
			0.4	1.44	0.56	Square	2.7
10	M5	A2	1.2	5.25	1.50	Circle	3.34
			0.8	3.00	1.00	Circle	2.49
			0.4	1.25	0.50	Circle	1.26
			1.2	6.24	1.69	Square	3.46
			0.8	3.52	1.13	Square	2.71
			0.4	1.44	0.56	Square	1.48
11	M5	A3	1.2	5.25	1.50	Circle	1.89
			0.8	3.00	1.00	Circle	1.32
			0.4	1.25	0.50	Circle	0.57
			1.2	6.24	1.69	Square	2.25
			0.8	3.52	1.13	Square	1.6
			0.4	1.44	0.56	Square	0.79
12	M5	A4	2.0	11.25	2.50	Circle	2.42
			1.2	5.25	1.50	Circle	1.56
			0.8	3.00	1.00	Circle	1.2
			0.4	1.25	0.50	Circle	0.56
			2.0	13.46	2.82	Square	2.6
			1.2	6.24	1.69	Square	1.81
			0.8	3.52	1.13	Square	1.32
			0.4	1.44	0.56	Square	0.62
14	M5	A7	2.0	11.25	2.50	Circle	5.1
			1.2	5.25	1.50	Circle	4.01
			0.8	3.00	1.00	Circle	2.98
			0.4	1.25	0.50	Circle	1.88
			2.0	13.46	2.82	Square	5.61
			1.2	6.24	1.69	Square	4.67
			0.8	3.52	1.13	Square	3.95
			0.4	1.44	0.56	Square	1.94
16*	M5	A4	1.2	5.25	1.50	Circle	1.87
			0.8	3.00	1.00	Circle	1.46
			0.4	1.25	0.50	Circle	0.62
			1.2	6.24	1.69	Square	2.12
			0.8	3.52	1.13	Square	1.7
			0.4	1.44	0.56	Square	0.77
17*	M5	A6	1.2	5.25	1.50	Circle	1.11
			0.8	3.00	1.00	Circle	0.79
			0.4	1.25	0.50	Circle	0.5
			1.2	6.24	1.69	Square	1.39
			0.8	3.52	1.13	Square	1.0
			0.4	1.44	0.56	Square	0.71
18*	M5	A8	1.2	5.25	1.50	Circle	1.64
			0.8	3.00	1.00	Circle	0.95
			0.4	1.25	0.50	Circle	0.59
			1.2	6.24	1.69	Square	1.73
			0.8	3.52	1.13	Square	1.44
			0.4	1.44	0.56	Square	0.75
19	M6	A2	1.2	5.25	1.50	Circle	2.72
			0.8	3.00	1.00	Circle	2.34
			0.4	1.25	0.50	Circle	1.61
			1.2	6.24	1.69	Square	2.97
			0.8	3.52	1.13	Square	2.97
			0.4	1.44	0.56	Square	1.83
20	M6	A3	1.2	5.25	1.50	Circle	2.62
			0.8	3.00	1.00	Circle	2.33
			0.4	1.25	0.50	Circle	1.92
			1.2	6.24	1.69	Square	2.95
			0.8	3.52	1.13	Square	2.51
			0.4	1.44	0.56	Square	1.82
21	M6	A7	1.2	5.25	1.50	Circle	5.04
			0.8	3.00	1.00	Circle	4.34
			0.4	1.25	0.50	Circle	3.26
			1.2	6.24	1.69	Square	5.43
			0.8	3.52	1.13	Square	4.88
			0.4	1.44	0.56	Square	3.59
22	M3	A7	1.2	5.25	1.50	Circle	4.0
			0.8	3.00	1.00	Circle	2.8
			0.4	1.25	0.50	Circle	1.92
			1.2	6.24	1.69	Square	4.17
			0.8	3.52	1.13	Square	3.22
			0.4	1.44	0.56	Square	1.88
23	M4	A3	1.2	6.24	1.69	Square	1.13
			0.8	3.52	1.13	Square	0.85
			0.4	1.44	0.56	Square	0.53
24	M4	A7	1.2	5.25	1.50	Circle	3.31
			0.8	3.00	1.00	Circle	2.59
			0.4	1.25	0.50	Circle	1.41
			1.2	6.24	1.69	Square	3.88
			0.8	3.52	1.13	Square	3.06
			0.4	1.44	0.56	Square	1.91
25**	M9	A1	1.2	5.25	1.50	Circle	2.13
			0.8	3.00	1.00	Circle	1.15
			0.4	1.25	0.50	Circle	0.83
26**	M9	A2	1.2	5.25	1.50	Circle	1.71
			0.8	3.00	1.00	Circle	1.13
			0.4	1.25	0.50	Circle	0.99
			1.2	6.24	1.69	Square	1.56
			0.8	3.52	1.13	Square	1.29
			0.4	1.44	0.56	Square	0.92
27**	M9	A10	1.2	5.25	1.50	Circle	1.91
			0.8	3.00	1.00	Circle	1.98
			0.4	1.25	0.50	Circle	1.41

# = Example number
* Samples heated at 70°C for 30 minutes.
** Samples heated at 125°C for 2 hours.

A plot of insertion loss as a function of frequency for example 14 is shown in Figures 7 and 8 showing that the insertion loss is reduced as the adhesive wall width is reduced from 2 mm to 1.2 mm to 0.8 mm (standard width) to 0.4 mm.
A plot of insertion loss as a function of frequency for example 21 is shown in Figures 9 and 10 showing that the insertion loss is reduced as the adhesive wall width is reduced from 0.8 mm (standard width) to 0.4 mm.
A plot of insertion loss as a function of frequency for example 12 is shown in Figures 11 and 12 showing that the insertion loss is reduced as the adhesive wall width is reduced from 0.8 mm (standard width) to 0.4 mm.
A plot of insertion loss as a function of frequency for example 22 is shown in Figures 13 and 14 showing that the insertion loss is reduced as the adhesive wall width is reduced from 0.8 mm (standard width) to 0.4 mm.
A plot of insertion loss as a function of frequency for examples 25, 26 and 27 is shown in Figures 16, 17 and 15 respectively showing that the insertion loss is reduced as the adhesive wall width is reduced from 0.8 mm (standard width) to 0.4 mm.
A plot of insertion loss as a function of frequency for examples 4 and 6 is shown in Figures 18 and 19 showing that the insertion loss is reduced as the adhesive wall width is reduced from 0.8 mm (standard width) to 0.4 mm.
For vent assemblies used in mobile electronic devices the standard width of the adhesive wall is typically 0.8 mm, corresponding to an Area Ratio of 3.0 and a Width Ratio of 1.0. As can be seen, reducing the Area Ratio to below 3.0 or the Width Ratio to below 1.0 for vent assemblies having suitable acoustic membranes, the insertion loss at 1kHz is also reduced corresponding to improved acoustic performance.
Conversely, if the Area Ratio is raised above 3.0 or the Width Ratio is raised above 1.0 for vent assemblies having suitable acoustic membranes, the insertion loss at 1 kHz is raised, corresponding to worse acoustic performance.
In contrast, the applicant has found that insertion loss is not changed significantly for vent assemblies comprising an acoustic membrane that has predominantly resistive characteristics.
It will be appreciated that whilst the present disclosure has been exemplified using the examples of Table 3, vent assemblies according to the present disclosure of larger or smaller dimensions to those provided in Table 3 would be expected to demonstrate similar benefits.
While there has been hereinbefore described approved embodiments of the present invention, it will be readily apparent that many and various changes and modifications in form, design, structure and arrangement of parts may be made for other embodiments without departing from the invention and it will be understood that all such changes and modifications are contemplated as embodiments as a part of the present invention as defined in the appended claims.
Further embodiments and examples are defined in the following numbered clauses:

1. A vent assembly comprising an acoustic membrane and an adhesive layer provided on a first side of the acoustic membrane, the acoustic membrane having a flow resistance of at least 1000 Pa s/m as measured using the method described herein, the adhesive layer having a surface area, the adhesive layer comprising an adhesive wall and the adhesive wall defining a venting aperture through which an active area of the acoustic membrane is exposed, wherein the ratio of the surface area of the adhesive layer to the surface area of the active area of the acoustic membrane ("Area Ratio") is less than 2.0.
2. The vent assembly of clause 1, wherein the ratio of the surface area of the adhesive layer to the surface area of the active area of the acoustic membrane is from 1.0 to 1.6.
3. The vent assembly of clause 2, wherein the ratio of the surface area of the adhesive layer to the surface area of the active area of the acoustic membrane is from 1.2 to 1.5.
4. The vent assembly of any preceding clause, wherein the acoustic membrane has a Young's modulus of at least 50 MPa.
5. The vent assembly of any preceding clause, wherein the acoustic membrane has a Young's modulus of from 50 MPa to 5000 MPa.
6. The vent assembly of any preceding clause, wherein the acoustic membrane has a thickness of less than 100 µm.
7. The vent assembly of any preceding clause, wherein the acoustic membrane has a thickness of from 0.1 µm to 90 µm.
8. The vent assembly of any preceding clause, wherein the acoustic membrane comprises a non-porous material.
9. The vent assembly of any of clause 1 to clause 7, wherein the acoustic membrane comprises a porous material.
10. The vent assembly of any preceding clause, wherein the acoustic membrane comprises a fluoropolymer selected from the group: polytetrafluoroethylene (PTFE), perfluoroalkoxy alkane (PFA), polyvinylfluoride (PVF), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), or polyethylenetetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), ethylene fluorinated ethylene propylene (EFEP), or co-polymers or combinations thereof.
11. The vent assembly of clause 10, wherein the fluoropolymer is selected from the group: PTFE, PFA and FEP.
12. The vent assembly of clause 11, wherein the fluoropolymer is PTFE.
13. The vent assembly of any of clause 1 to clause 9, wherein the acoustic membrane comprises a non-fluoropolymer selected from the group: polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyurethane (PU), or co-polymers or combinations thereof.
14. The vent assembly of clause 13, wherein the non-fluoropolymer is selected from the group: PE, and PU.
15. The vent assembly of any preceding clause, wherein the acoustic membrane comprises PTFE, PE, or PU or combinations or co-polymers thereof.
16. The vent assembly of clause 14 or clause 15, wherein the acoustic membrane comprises PE.
17. The vent assembly of clause 14 or clause 15, wherein the acoustic membrane comprises PU.
18. The vent assembly of any preceding clause, wherein the adhesive layer comprises an acrylic adhesive, or a silicone adhesive.
19. The vent assembly of any preceding clause, wherein the adhesive layer comprises a heat activated adhesive, a pressure adhesive, or an ultraviolet curable adhesive.
20. The vent assembly of any preceding clause, wherein the adhesive layer comprises a carrier substrate having a first major surface and a second major surface and adhesive is provided on the first major surface and the second major surface.
21. The vent assembly of any preceding clause, wherein the adhesive wall has a substantially uniform width.
22. A vent assembly comprising an acoustic membrane and an adhesive layer provided on a first side of the acoustic membrane, the acoustic membrane having a flow resistance of at least 1000 Pa s/m as measured using the method described herein, the adhesive layer comprising an adhesive wall defining a venting aperture through which an active area of the acoustic membrane is exposed, the vent assembly having a width comprising a width of the active area of the acoustic membrane and a width of the adhesive wall either side the venting aperture, wherein the ratio of the sum of the widths of the adhesive wall either side of the venting aperture to the width of the active area of the acoustic membrane ("Width Ratio") is less than 1.0.
23. The vent assembly of clause 22, wherein the ratio of the sum of the widths of the adhesive wall either side of the venting aperture to the width of the active area of the membrane is from 0.1 to 0.9.
24. The vent assembly of clause 22 or clause 23, wherein the acoustic membrane has a Young's modulus of at least 50 MPa.
25. The vent assembly of any of clause 22 to clause 24, wherein the acoustic membrane has a Young's modulus of from 50 MPa to 5000 MPa.
26. The vent assembly of any of clause 22 to clause 25, wherein the acoustic membrane has a thickness of less than 100 µm.
27. The vent assembly of any of clause 22 to clause 26, wherein the acoustic membrane has a thickness of from 0.1 µm to 90 µm.
28. The vent assembly of any of clause 22 to clause 27, wherein the acoustic membrane comprises a non-porous material.
29. The vent assembly of any of clause 22 to clause 27, wherein the acoustic membrane comprises a porous material.
30. The vent assembly of any of clause 22 to clause 29, wherein the acoustic membrane comprises a fluoropolymer selected from the group: polytetrafluoroethylene (PTFE), perfluoroalkoxy alkane (PFA), polyvinylfluoride (PVF), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), or polyethylenetetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), ethylene fluorinated ethylene propylene (EFEP), or co-polymers or combinations thereof.
31. The vent assembly of clause 30, wherein the fluoropolymer is selected from the group: PTFE, PFA and FEP.
32. The vent assembly of clause 31, wherein the fluoropolymer is PTFE.
33. The vent assembly of any of clause 22 to clause 29, wherein the acoustic membrane comprises a non-fluoropolymer selected from the group: polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyurethane (PU), or co-polymers or combinations thereof.
34. The vent assembly of clause 33, wherein the non-fluoropolymer is selected from the group: PE, and PU.
35. The vent assembly of any of clause 22 to clause 34, wherein the acoustic membrane comprises PTFE, PE, or PU or combinations or co-polymers thereof.
36. The vent assembly of clause 34 or clause 35, wherein the acoustic membrane comprises PE.
37. The vent assembly of clause 34 or clause 35, wherein the acoustic membrane comprises PU.
38. The vent assembly of any of clause 22 to clause 37, wherein the adhesive layer comprises an acrylic adhesive, or a silicone adhesive.
39. The vent assembly of any of clause 22 to clause 38, wherein the adhesive layer comprises a heat activated adhesive, a pressure adhesive, or an ultraviolet curable adhesive.
40. The vent assembly of any of clause 22 to clause 39, wherein the adhesive layer comprises a carrier substrate having a first major surface and a second major surface and adhesive is provided on the first major surface and the second major surface.
41. The vent assembly of any of clause 22 to clause 40, wherein the adhesive wall has a substantially uniform width.
42. An electronic device comprising a housing and an acoustic transducer, the housing defining an acoustic aperture and a vent assembly of any preceding clause occluding the acoustic aperture such that the adhesive layer adheres the vent assembly to the housing around the acoustic aperture, wherein the acoustic transducer is positioned adjacent to the acoustic aperture.
43. The electronic device of clause 42, wherein the acoustic transducer is a speaker or a microphone.

Claims

A vent assembly comprising an acoustic membrane and an adhesive layer provided on a first side of the acoustic membrane, the acoustic membrane having a flow resistance of at least 1000 Pa s/m as measured using the method described herein, the adhesive layer having a surface area, the adhesive layer comprising an adhesive wall and the adhesive wall defining a venting aperture through which an active area of the acoustic membrane is exposed, wherein the ratio of the surface area of the adhesive layer to the surface area of the active area of the acoustic membrane ("Area Ratio") is less than 2.0.
The vent assembly of claim 1, wherein the ratio of the surface area of the adhesive layer to the surface area of the active area of the acoustic membrane is from 1.0 to 1.6, optionally from 1.2 to 1.5.
The vent assembly of any preceding claim, wherein the acoustic membrane has a Young's modulus of at least 50 MPa.
The vent assembly of any preceding claim, wherein the acoustic membrane has a thickness of less than 100 µm.
The vent assembly of any preceding claim, wherein the acoustic membrane comprises a fluoropolymer selected from the group: polytetrafluoroethylene (PTFE), perfluoroalkoxy alkane (PFA), polyvinylfluoride (PVF), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), or polyethylenetetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), ethylene fluorinated ethylene propylene (EFEP), or co-polymers or combinations thereof, optionally wherein the fluoropolymer is selected from the group: PTFE, PFA and FEP.
The vent assembly of any of claim 1 to claim 9, wherein the acoustic membrane comprises a non-fluoropolymer selected from the group: polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyurethane (PU), or co-polymers or combinations thereof, optionally the non-fluoropolymer is selected from the group: PE, and PU.
The vent assembly of any preceding claim, wherein the adhesive layer comprises an acrylic adhesive, or a silicone adhesive.
The vent assembly of any preceding claim, wherein the adhesive layer comprises a carrier substrate having a first major surface and a second major surface and adhesive is provided on the first major surface and the second major surface.
The vent assembly of any preceding claim, wherein the adhesive wall has a substantially uniform width.
A vent assembly comprising an acoustic membrane and an adhesive layer provided on a first side of the acoustic membrane, the acoustic membrane having a flow resistance of at least 1000 Pa s/m as measured using the method described herein, the adhesive layer comprising an adhesive wall defining a venting aperture through which an active area of the acoustic membrane is exposed, the vent assembly having a width comprising a width of the active area of the acoustic membrane and a width of the adhesive wall either side the venting aperture, wherein the ratio of the sum of the widths of the adhesive wall either side of the venting aperture to the width of the active area of the acoustic membrane ("Width Ratio") is less than 1.0.
The vent assembly of claim 10, wherein the ratio of the sum of the widths of the adhesive wall either side of the venting aperture to the width of the active area of the membrane is from 0.1 to 0.9.
The vent assembly of claim 10 or claim 11, wherein the acoustic membrane has a Young's modulus of at least 50 MPa.
The vent assembly of any of claim 10 to claim 12, wherein the acoustic membrane has a thickness of less than 100 µm.
The vent assembly of any of claim 10 to claim 13, wherein the acoustic membrane comprises a fluoropolymer selected from the group: polytetrafluoroethylene (PTFE), perfluoroalkoxy alkane (PFA), polyvinylfluoride (PVF), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), or polyethylenetetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), ethylene fluorinated ethylene propylene (EFEP), or co-polymers or combinations thereof, optionally the fluoropolymer is selected from the group: PTFE, PFA and FEP.
The vent assembly of any of claim 10 to claim 13, wherein the acoustic membrane comprises a non-fluoropolymer selected from the group: polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyurethane (PU), or co-polymers or combinations thereof, optionally the non-fluoropolymer is selected from the group: PE, and PU.
The vent assembly of any of claim 10 to claim 15, wherein the adhesive layer comprises an acrylic adhesive, or a silicone adhesive.
The vent assembly of any of claim 10 to claim 16, wherein the adhesive layer comprises a carrier substrate having a first major surface and a second major surface and adhesive is provided on the first major surface and the second major surface.
The vent assembly of any of claim 10 to claim 17, wherein the adhesive wall has a substantially uniform width.
An electronic device comprising a housing and an acoustic transducer, the housing defining an acoustic aperture and a vent assembly of any preceding claim occluding the acoustic aperture such that the adhesive layer adheres the vent assembly to the housing around the acoustic aperture, wherein the acoustic transducer is positioned adjacent to the acoustic aperture.
The electronic device of claim 19, wherein the acoustic transducer is a speaker or a microphone.