Acoustic cover assembly including retractable membrane material

Abstract

The acoustic protection cover assembly may include a retractable membrane material that traverses an acoustic path defined by an opening in the shell. The retractable membrane material may include a fibril structure characterized by tortuous fibrils.

Description

[0001] This application is a divisional case of the Chinese invention patent application with application number 201780065043.X and invention name “Acoustic protective cover assembly comprising retractable membrane material” (hereinafter referred to as the “parent case”) filed by the applicant WL Gore & Associates Co., Ltd. The parent case is the Chinese national phase of the international application PCT / US2017 / 057623, with an international application date of October 20, 2017, claiming priority to US 62 / 411470.

[0002] Cross-reference to related applications

[0003] This application claims the benefit of U.S. Provisional Application No. 62 / 411,470, filed October 21, 2016, which is incorporated herein by reference in its entirety for all purposes. Technical Field

[0004] The present disclosure relates generally to acoustic polymer membranes. More particularly, but not by way of limitation, the present disclosure relates to boot assemblies comprising retractable polymer membrane materials. Background Art

[0005] Acoustic protection technology is used in many applications and environments to protect sensitive components of acoustic equipment from environmental conditions. The various components of acoustic equipment function best when they are protected from debris, water, or other contaminants from the external environment. In particular, acoustic transducers (e.g., microphones, speakers) can be sensitive to dirt. For these reasons, it is often necessary to surround the working components of an acoustic device with an acoustic enclosure.

[0006] Known protective acoustic shields include non-porous membranes and porous membranes, such as expanded polytetrafluoroethylene (ePTFE). Protective acoustic shields are also described in U.S. Patents 6,512,834 and 5,828,012. The shield can transmit sound in two ways: by allowing sound waves to pass through it, known as a resistive shield; or by vibrating to generate sound waves, known as a vibroacoustic or reactive shield.

[0007] Japanese Patent Publication No. 2015-142282 discloses a waterproof component having a waterproof and sound-transmitting membrane. A support layer is adhered to the surface of at least one side of the waterproof and sound-transmitting membrane. The support layer is a polyolefin resin foam having a loss modulus of less than 1.0×10 7 Pa.

[0008] US Patent No. 6,188,773 discloses a waterproof microphone including a microphone housing provided with a unit accommodating chamber having a sound receiving opening portion; a microphone unit accommodated in the unit accommodating chamber; and a waterproof membrane airtightly mounted on the sound receiving opening portion.

[0009] US Patent Publication No. 2014 / 0270273 discloses a system and method for controlling and adjusting the low-frequency response of a MEMS microphone. The MEMS microphone includes a membrane and a plurality of vents. The membrane is configured such that sound pressure acting on the membrane causes the membrane to move.

[0010] US Patent Publication No. 2015 / 0163572 discloses a speaker or microphone module including an acoustic membrane and at least one pressure vent.

[0011] It has long been a problem that many acoustic enclosure membranes have proven to be unsuitable for certain environments. For example, increasing the elasticity of the membrane in an acoustic protection assembly to prevent water penetration can reduce the assembly's ability to properly transmit sound.

[0012] Brief Overview of Some Implementations

[0013] According to one embodiment of the present invention, a protective cover assembly for an acoustic device is disclosed. The protective cover assembly includes a shell having an opening for transmitting sound waves between the exterior of the shell and an acoustic cavity therein; and an acoustic diaphragm connected to the shell and separating the acoustic cavity from the exterior of the shell. The acoustic diaphragm has an acoustic insertion loss of less than 6 dB at 1 kHz and is resistant to water penetration, for example, with a water inlet pressure (WEP) of at least 9.8 kPa. In some embodiments, the acoustic diaphragm can be 2 The membrane working area has an ATEQ airflow rate of at least 10 L / hour.

[0014] In various embodiments, the acoustic membrane of the boot assembly comprises an expanded fluoropolymer membrane. In some specific embodiments, the acoustic membrane is an ePTFE membrane or an ePTFE composite. When the acoustic membrane is formed by shrinking (i.e., heat shrinking), the acoustic membrane made of the shrinking membrane material can have an area ratio of less than 75% of the corresponding precursor membrane.

[0015] In at least one embodiment, a protective acoustic cover for an acoustic device is disclosed. The acoustic cover may have a microstructure comprising tortuous fibrils. In some cases, the acoustic membrane may have an inner diameter of 1.6 mm or greater. In some embodiments, the acoustic membrane may be less than 1.6 mm, such as less than 1.5 mm, such as less than 1.25 mm, such as less than 1 mm, or less. In some embodiments, the acoustic membrane may have an acoustic insertion loss of, for example, less than 6 dB at 1 kHz, such as less than 5 dB at 1 kHz, less than 4 dB at 1 kHz, less than 3 dB at 1 kHz, or less than 1 dB at 1 kHz. In various embodiments, the acoustic membrane may have an acoustic insertion loss of less than 1 dB per 2.0 cm. 2 The acoustic enclosure has an ATEQ airflow rate of at least 10 L / hour. In some embodiments, the acoustic enclosure is an expanded fluoropolymer membrane. The expanded fluoropolymer membrane may have an acoustic insertion loss of less than 4 dB at 1 kHz, less than 3 dB at 1 kHz, or less than 1 dB at 1 kHz.

[0016] The acoustic enclosure may include an expanded fluoropolymer membrane. According to some embodiments, the membrane may have a strength greater than or equal to 6 g / m 2 The acoustic enclosure may have a density greater than or equal to 7 g / m 2 The expanded fluoropolymer film can be formed at a density of less than 15 μm and a thickness of less than 15 μm. 2 having an ATEQ airflow rate of at least 15 L / hour.In certain embodiments, the membrane may be water-impermeable to a pressure of at least 9.8 kPa.

[0017] In at least one embodiment, an acoustic membrane for an acoustic device is disclosed, comprising a retractable membrane material. The retractable membrane material may have an acoustic insertion loss of less than 5 dB at 1 kHz and may have a WEP of at least 9.8 kPa. In some embodiments, the retractable membrane material may have an acoustic insertion loss of less than 5 dB at 1 kHz and a WEP of at least 9.8 kPa. 2 The shrink film material may have an ATEQ airflow rate of at least 10 L / hour. In certain embodiments, the shrink film material may have an area ratio of less than 0.75:1 (i.e., less than 75%) relative to the initial area of ​​the precursor film. In some embodiments, the shrink film material may be heat-shrinkable. In some other embodiments, the shrink film material may be solvent-shrinkable.

[0018] In some embodiments, the shrink film material has a thickness of at least 6.9 g / m 2 The shrink film material may be air permeable but water impermeable. For example, the shrink film material may be water impermeable to a pressure of at least 9.8 kPa.

[0019] These and other embodiments, as well as many of their advantages and features, are described in more detail in conjunction with the following description and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The invention will be better understood with reference to the attached non-limiting drawings.

[0021] Figure 1 shows a cross-sectional view of an acoustic device having an acoustic protective cover assembly including a retractable membrane material according to some embodiments;

[0022] Figure 2 shows a series of SEM micrographs showing a precursor of a retracted film material, the precursor in a retracted state, and the retracted film material in a partially relaxed state according to some embodiments;

[0023] Figure 3 SEM micrograph showing the film of the first comparative example;

[0024] Figure 4 SEM micrograph showing the film of the second comparative example;

[0025] Figure 5 An SEM micrograph showing a retraction film material of a first example of some embodiments;

[0026] Figure 6 An SEM micrograph showing a retraction film material of a second example of some embodiments;

[0027] Figure 7 An SEM micrograph showing a retraction film material of a third example of some embodiments;

[0028] Figure 8 is a side view illustrating a test assembly for testing performance characteristics of an acoustic membrane; and

[0029] Figure 9 is a graph illustrating the insertion loss (ie, the difference in sound pressure level compared to an unobstructed microphone) for various embodiments of an acoustic protective cover. DETAILED DESCRIPTION

[0030] Various embodiments described herein relate to acoustic protective cover assemblies for acoustic devices. Specifically, some embodiments herein relate to retractable acoustic membranes comprising a membrane material containing tortuous fibrils.

[0031] The acoustic shield assembly described above includes a retractable acoustic membrane that provides moisture resistance and prevents water penetration. In one embodiment, the acoustic shield includes a retractable membrane material for high-immersion applications. Advantageously, the membrane provides resistance to moisture and protects the acoustic device from potential damage from the external environment. Assemblies incorporating the acoustic membrane described herein exhibit improved performance in transmitting sound while maintaining comparable or improved protection compared to conventional assemblies that do not utilize retractable membrane material.

[0032] Protective cover assembly

[0033] Figure 1 A cross-sectional view of a protective cover assembly 100 for an acoustic device 102 is shown according to some embodiments. The acoustic device 102 can be an electronic device for generating and / or receiving sound waves, for example at a transducer 104. An acoustic cavity 114 adjacent to the transducer 104 transfers the sound waves to or from the transducer. In some embodiments, the transducer 104 can be a microphone or other acoustic sensor, a speaker, a pressure sensor, or other similar type of sensor. In some embodiments, the transducer 104 can be a micro-electromechanical (MEM) device, such as a microphone, an acoustic sensor, or an acoustic speaker. The acoustic device 102 can be an electronic circuit board, such as a flexible circuit, on which the transducer 104 is included. In some embodiments, the acoustic device 102 can be a sensing module or control circuit for a portable electronic device, such as a mobile phone, a smart phone, a tablet computer, a portable microphone, a handheld computing device, or other similar device.

[0034] Acoustic device 102 is at least partially enclosed by a housing 106, which protects acoustic device 102 from an external environment 108 and can be at least partially sealed and / or waterproof. Housing 106 can be a plastic or metal shell. Housing 106 contains an interior environment 110 that at least partially surrounds acoustic device 102.

[0035] The acoustic passage 112 is defined in part by an opening 116 in the housing 106. Figure 1, in other embodiments, there may be multiple openings in the housing 106 that collectively or individually define an acoustic pathway. An opening 116 in the housing 106 is used to transmit sound waves between the exterior 108 of the housing 106 and an acoustic cavity 114 therein. In one embodiment, the acoustic pathway 112 is configured to allow pressure waves, i.e., sound waves, to propagate from the exterior of the housing 106 to the transducer 104 of the acoustic device 102 when sound is detected. Similarly, in other embodiments, the acoustic pathway 112 is configured to allow pressure waves generated by the acoustic device 102 to propagate toward the exterior of the housing 106. The acoustic pathway 112 is intersected by a retractable membrane material 120, which further defines the acoustic cavity 114. Because the retractable membrane material 120 intersects the acoustic pathway 112, the retractable membrane 120 may also be referred to herein as an acoustic membrane or an acoustic diaphragm. The acoustic cavity 114 is disposed between the retractable membrane material 120 and a portion of the acoustic device 102 that includes the transducer 104. To provide adequate acoustical containment, the minimum diameter of the retraction membrane material 120 is at least equal to or greater than the maximum diameter of the opening 116. The maximum diameter of the opening 116 can vary depending on the application and configuration of the housing 106. The acoustic protection assembly is suitable for openings of any size and is not particularly limited. In one exemplary embodiment, the diameter of the opening 116 is between 0.1 mm and 500 mm, such as between 0.3 mm and 25 mm, or between 0.5 mm and 10 mm. Based on these exemplary opening diameters, the minimum diameter of the retraction membrane material is at least 0.1 mm, such as at least 0.3 mm, such as at least 0.5 mm, such as at least 1.0 mm, such as at least 1.5 mm, or such as at least 1.6 mm. Having this dimensional relationship allows the retraction membrane material 120 to fully intersect the acoustic channel 112 and prevent the intrusion of fluids or moisture into the acoustic cavity 114. The interior environment 110 of the housing 106 is also at least partially sealed by the retraction membrane material 120 from the intrusion of fluids or moisture from the external environment.

[0036] The retraction membrane material 120 can be secured between the acoustic device 102 and the housing 106 by, for example, a first layer 118 (or multiple layers) and a second layer 122 (or multiple layers). The first layer 118 and the second layer 122 can include any suitable means for securing the membrane, such as an adhesive layer (i.e., a double-sided adhesive layer), a breathable layer for promoting air exchange between the acoustic cavity 114 and the interior 110 of the housing 106 (e.g., the second layer or multiple layers 122 can include a breathable layer). In some embodiments, the retraction membrane material 120 can be held between the housing 106 and the acoustic device 102 by a mechanical clamping force, with or without the aid of an adhesive. In certain embodiments, the first layer 118 can be an extension of the housing 106.

[0037] In some embodiments, the total thickness of the retraction membrane material 120 and the first layer 118 and the second layer 122 can be on the order of about 25 μm to about 2500 μm. In one embodiment, the total thickness of the stacked assembly can be on the order of about 100 μm to less than 1000 μm. Without limitation, in some exemplary applications, the acoustic device can be used in conjunction with a MEMs transducer having a relatively small thickness (e.g., on the order of about 100 μm to 1000 μm). Therefore, the acoustic device including the retraction membrane material 120 can be very thin, on the order of about 0.2 to 1.2 mm, which is suitable for inclusion in many small applications, such as handheld electronic devices.

[0038] In some embodiments, the retraction membrane material can be a polymer composite material layer, which can also be non-porous, microporous or porous. Various non-porous materials that can be used for retraction membrane materials can include polymer films (such as TPU, PET, siloxanes, polystyrene block copolymers, FEP, etc.) or polymer composites. Porous materials can include expanded polytetrafluoroethylene (ePTFE) materials and ePTFE composite materials, which provide a good balance of acoustics and waterproofing. Various porous and non-porous materials, in addition to being very thin and lightweight, also have excellent acoustic transmissibility and provide excellent waterproofing. In some cases, the membrane material can be processed. For example, before or after the membrane material retracts, the membrane material can include an oleophobic coating, such as formed by an oleophobic polymer.

[0039] In various embodiments, the shrink film material has a microstructure comprising zigzag fibrils. As used herein, the term "zigzag fibrils" refers to a plurality of fibrils that bend or fold in one direction and then bend or fold in another direction. The width of the zigzag fibrils may typically be less than or equal to about 1.0 microns. The zigzag fibrils may be connected by nodes. The zigzag fibrils may be formed by controlled retraction, for example, as described in U.S. Patent Publication No. 2013 / 0183515. "Controlled retraction" may be achieved by shortening the length of the article in at least one direction by heating, wetting with a solvent, or any other suitable method or combination thereof, thereby inhibiting the subsequent article from folding, pleating, or wrinkling that is visible to the naked eye. The shrink film may be produced by retracting a precursor film to convert most of the fibrils therein into zigzag fibrils. In some cases, an article that has been retracted according to the teachings of the present disclosure may need to be stretched in the direction of retraction to identify the zigzag fibrils.

[0040] In one embodiment, the retraction membrane may have a thickness of no greater than 100 μm, no greater than 50 μm, or no greater than 20 μm. In some embodiments, the retraction membrane may have a thickness of no greater than 16 μm, no greater than 14 μm, no greater than 12 μm, or no greater than 10 μm. The retraction membrane is thick enough to resist bursting under pressure caused by external pressure fluctuations and / or temperature fluctuations in the acoustic cavity, while being thin enough to minimally hinder the passage of acoustic energy through the retraction membrane. The retraction membrane is thick enough to resist excessive deformation of the membrane, which would adversely affect the acoustic performance. According to some embodiments, the surface density (i.e., mass per unit area) of the retraction membrane may be, for example, less than 15 g / m 2 , less than or equal to 12g / m 2 , or less than or equal to 10g / m 2 varies within the range of .

[0041] The adhesive layer (e.g., first and second layers 118, 122) can be formed from any suitable layer having an adhesive surface on each side for connecting two parts. For example, the adhesive layer can be a polymer layer impregnated with an adhesive surface treatment, similar to a double-sided tape. The adhesive layer can include a double-sided self-adhesive tape comprising a PET backing and a tackified acrylic adhesive (e.g., 4972). The adhesive layer can have varying thicknesses depending on the desired thickness of the pressure balancing assembly. Exemplary adhesive layers can be any suitable thickness on the order of about 5 to 1000 μm. In certain embodiments, multiple adhesive layers can be stacked together to provide additional height, for example, to increase the volume of the acoustic cavity 114, to increase the offset between the housing 106 and the retraction membrane material 120, or both. Specific examples of adhesive layers are about 30 μm thick, or about 48 μm thick. Typically, the adhesive layers are waterproof and non-porous. In one embodiment, the adhesive layer adjacent to the external environment is waterproof, while the other adhesive layers can be waterproof.

[0042] The present invention will be better understood with reference to the following non-limiting examples and test results.

[0043] Example film

[0044] Figure 2 A series of SEM micrographs 200 showing a precursor 202 of a retracted film material, a precursor in a retracted state (204), and a retracted film material in a partially relaxed state (206) according to some embodiments of the present disclosure are shown. The precursor 202 is a microporous expanded functionalized tetrafluoroethylene (TFE) copolymer, or ePTFE copolymer, whose microstructure is characterized by nodes interconnected by fibrils, similar to the functionalized TFE copolymers described, for example, in U.S. Patent No. 3,953,566.

[0045] It should be understood that comparable fibrillated polymeric materials may also be suitable precursors for retraction film materials, including film materials containing greater or lesser ratios of nodes to fibrils, or substantially different microstructures, as described, for example, in U.S. Patent Nos. 5,814,405 and 4,902,423. Figure 4 , a specific precursor film 202 is shown and discussed further in FIG. This film is commercially available from WL Gore & Associates, Inc. as part number GAW 333.

[0046] The heat-shrinkable film can be formed by shrinking the precursor 202 at an elevated temperature while controlling the degree of shrinkage. For example, the shrinking state 204 can be achieved by shrinking the precursor 202 to an area ratio of approximately 0.58:1 relative to the original area of ​​the precursor 202 under heating at 300°C. This shrinkage causes the fibrils to deform and assume a tortuous structure and appearance.

[0047] The precursor 202 can be shrunk by methods other than heat shrinking to form a film having tortuous fibrils. For example, in some embodiments, a solvent-shrunk film can be formed by applying a solvent (e.g., isopropyl alcohol) to the precursor and drying the solvent from the film while the film is free.

[0048] A fully retracted precursor 204 may also be partially relaxed or unretracted by applied tension. Figure 2 The partially relaxed retracted film material 206 is shown as having partially retracted to an area ratio of approximately 0.575:1 relative to the original precursor 202.

[0049] Reference below Figure 3-7 Other examples of precursor films and retraction films are discussed in conjunction with Table 1 below.

[0050] Table 1

[0051]

[0052] The final / initial area ratio is a measure of the shrinkage of a membrane compared to its respective precursor membrane. The ATEQ airflow rate is a measure of the air permeability of a membrane, which is measured by the ATEQ airflow test described below as liters of airflow through a given membrane per unit time. In each case, the sample was a membrane formed into a circular acoustic hood with an inner diameter of 1.6 mm. Insertion loss is a measure of the extent to which a given membrane blocks sound from passing through the membrane, which is measured in an insertion loss detection test described below. Insertion loss is measured as a sound pressure difference that is detected by a detection assembly due to the obstruction of the membrane. Comparative Examples 1 and 2 are unretracted membrane materials, which are also used herein as precursors to various example membranes. The example membranes, Examples 1-7, are retracted membrane materials produced by retracting the precursor membrane.

[0053] The formation of tortuous fibrils can be performed by the following techniques: heat-induced controlled retraction of expanded polytetrafluoroethylene (ePTFE); wetting the article with a solvent, including, for example, but not limited to, isopropyl alcohol or (a perfluorinated solvent available from 3M, Inc., St. Paul, MN, USA); or a combination of the above two technologies.

[0054] Comparative Example 1:

[0055] Figure 3 The SEM micrograph of the film of the first comparative example 300 is shown. The film 300 of the first comparative example was manufactured according to U.S. Patent No. 7,306,729 and had a mass per unit area of ​​5.2 g / m 2 , the bubble point is 924kPa, and the pressure is 12mbar through 2.0cm 2 The ATEQ airflow rate is 10.1 L / hour, the thickness is 16.4 microns, the mass per unit area is 5.2 g / m2, the bubble point is 924 kPa, the ATEQ airflow rate is 10.1 L / hour, passing through 2.0 square centimeters, the pressure difference is 12 mbar, the thickness is 16.4 microns, and the longitudinal and transverse matrix tensile strengths are 314 MPa and 419 MPa respectively.

[0056] Comparative Example 2:

[0057] Figure 4 An SEM micrograph of a film of a second comparative example 400 is shown. The second comparative example film was made according to U.S. Patent No. 3,953,566, as described above with reference to Figure 2 The precursor film 202 is described as discussed above.

[0058] Example 1:

[0059] Figure 5 An SEM micrograph of a first embodiment 500 of a shrink film material according to some embodiments is shown. The shrink film material of the first embodiment 500 was produced using the first comparative example 300 as a precursor. The precursor was biaxially constrained in a frame and placed in an oven at 320°C for 30 seconds to shrink in the transverse direction to an area ratio of approximately 0.74:1 relative to its initial area, and then allowed to cool to room temperature. The resulting shrink film material 400 had a mass per unit area of ​​6.9 g / m 2 , ATEQ airflow rate is 16.8L / hour and thickness is 12.9 microns.

[0060] Notably, the retraction film material of the first embodiment 500 exhibited improved ATEQ airflow rate compared to its predecessor (the first comparative example 300). Furthermore, the first embodiment 500 exhibited a significantly reduced insertion loss of 3.4 dB, compared to the predecessor's insertion loss of 6.1 dB. These results demonstrate that both sound transmission (as opposed to insertion loss) and airflow rate (ATEQ airflow) were improved. This result is particularly surprising, as one would typically expect that increasing film density would be accompanied by a loss in at least one of airflow performance or sound transmission.

[0061] Example 2:

[0062] Figure 6 An SEM micrograph of a second embodiment 600 of a shrink film material according to some embodiments is shown. The shrink film material of the second embodiment 600 was produced using the film 500 of the first embodiment as a precursor. The precursor was shrunk to an area ratio of approximately 0.73:1 relative to its initial area. The resulting film 600 of the second embodiment exhibited a mass per unit area of ​​7.0 g / m 2 , ATEQ airflow rate is 17.3L / hour and thickness is 14.2 microns.

[0063] The membrane 600 of the second embodiment achieved similar performance to the membrane 500 of the first embodiment. For example, the membrane 600 of the second embodiment achieved a higher ATEQ airflow rate than the membrane 500 of the first embodiment (17.3 L / hour compared to 16.8 L / hour), with only a slight increase in insertion loss (3.9 dB compared to 3.4 dB). Both performance indicators were substantially improved compared to the initial precursor, i.e., the membrane 300 of the first comparative example.

[0064] Example 3:

[0065] The shrink film material of the third embodiment is derived from the precursor based on the first comparative example 300. The film of the third embodiment shrinks at a temperature of 360°C with an area ratio of 0.38:1 in the transverse direction. The mass per unit area of ​​the film thus obtained is 13.3 g / m 2 The ATEQ airflow rate is 11.9 L / hour and the thickness is 10 μm. The retractable film material of the third embodiment achieves an insertion loss of 3.8 dB and an ATEQ airflow rate of 11.9 L / hour.

[0066] Example 4:

[0067] The shrink film material of the fourth embodiment is derived from the precursor based on the first comparative example 300. The film of the fourth embodiment shrinks at a temperature of 360°C with an area ratio of 0.56:1 in the transverse direction. The mass per unit area of ​​the film thus obtained is 9.1 g / m 2The ATEQ value is 20 L / hour and the thickness is 11.4 μm. The retractable film material of the fourth embodiment achieves an insertion loss of 2.4 dB and an ATEQ airflow rate of 20.0 L / hour.

[0068] Example 5:

[0069] The shrink film material of the fifth embodiment is derived from the precursor based on the first comparative example 300. The film of the fifth embodiment shrinks at a temperature of 320°C with an area ratio of 0.45:1 in the transverse direction. The mass per unit area of ​​the film thus obtained is 11.3 g / m 2 The ATEQ value is 15.2 L / hour and the thickness is 14 microns. The retractable film material of the fifth embodiment achieves an insertion loss of 3.6 dB and an ATEQ airflow rate of 15.2 L / hour.

[0070] Example 6:

[0071] The shrink film material of the sixth embodiment is derived from the precursor based on the first comparative example 300. The film of the sixth embodiment shrinks at a temperature of 320°C with an area ratio of 0.61:1 in the transverse direction. The mass per unit area of ​​the film thus obtained is 8.4 g / m 2 The ATEQ airflow rate is 16.5 L / hour and the thickness is 14 μm. The retractable film material of the fifth embodiment achieves an insertion loss of 4.1 dB and an ATEQ airflow rate of 16.5 L / hour.

[0072] Example 7:

[0073] Figure 7 The SEM micrograph of the retraction film material of the seventh embodiment 700 of some embodiments is shown. The film 700 of the seventh embodiment differs from the films 1-6 in that it is derived from the film 400 based on the second comparative example (e.g., Figure 4 The film 700 of the seventh embodiment is also Figure 2 204 and 206. Figure 2 As described above, the film 700 of the seventh embodiment shrinks to an area ratio of 0.57:1 relative to its precursor film when heated to 320°C. The film 700 of the seventh embodiment shrinks in the transverse direction, and the unit area mass of the obtained film material is 6.9 g / m 2 , ATEQ airflow rate of 18.5 L / hour, thickness of 12 microns. Like the retraction film materials of the previous embodiments, the film 700 of the seventh embodiment achieves an improvement in insertion loss relative to its precursor film (0.7 dB compared to 1.2 dB), while achieving an airflow performance of 18.5 L / hour in the ATEQ airflow test.

[0074] Test Method

[0075] Insertion loss detection test

[0076] Figure 8 An exemplary test assembly 800 for testing insertion loss is shown. Insertion loss can be tested by connecting each exemplary membrane (comparative example membrane and retraction membrane material) to the hole 848 of the sample holding plate 842, completely surrounding the assembly, and measuring the sound generated by the speaker and passing through the hole and the assembly.

[0077] Each sample 802 is formed into a circular acoustic enclosure with an inner diameter of 1.6 mm, for example, by means of an adhesive ring 804, and is placed over a circular hole 848 with a diameter of 1 mm on a sample holding plate 842 by means of an adhesive layer 844. The sample is placed in a B&K model 4232 anechoic test box 6.5 cm away from the internal driver or speaker. The SPA2410LR5H MEMS measurement microphone 846 is assembled with the sample holding plate 842 by welding, for example.

[0078] The loudspeaker was excited to produce an external stimulus 806 at a sound pressure of 1 Pa (94 dB SPL) within the frequency range of 100 Hz to 11.8 kHz. The measurement microphone 846 measured the acoustic response as the sound pressure level in dB within the aforementioned frequency range. The measurements were taken with the hole 848 uncovered, i.e., without the sample 802, for calibration of the loss detection test. The measurements were taken by introducing each corresponding example as the sample 802.

[0079] Figure 9 Graph 900 is shown, which illustrates the insertion loss of Comparative Examples 1-2 and Examples 1-7 discussed above and listed in Table 1. Graph 900 shows the insertion loss of the reference 1-2 and Examples 1-7 in combination with the test assembly. Figure 2-7 The insertion loss (i.e., the sound pressure level difference compared to an unobstructed microphone) at a frequency of 1 kHz for various embodiments of the pressure balancing assembly described above, the test assembly being similar to Figure 8 Test assembly 800 is shown. Graph 900 shows error bars reflecting one standard deviation in the insertion loss measurements.

[0080] ATEQ airflow testing

[0081] ATEQ Airflow is a test method for measuring the laminar volume flow rate of air through a membrane sample. For each sample, a 2.0 cm 2Samples were produced in the form of membranes with an area of ​​1.5 mm. The samples were sandwiched between two plates so that they were sealed across the flow path. The airflow rate (L / hour) through each acoustic membrane sample was measured using an ATEQ Premier D Compact Flow Tester by challenging each membrane sample with a 1.2 kPa (12 mbar) pressure differential across the flow path.

[0082] Water Entry Pressure (WEP) Test

[0083] The WEP is determined in a manner similar to the ATEQ air flow test by subjecting the sample in the test assembly to water pressure differentials of 34.5 and 500 kPa across the flow passage.

[0084] Bubble point test

[0085] The bubble point was measured by a CFP-1500 capillary flow porometer manufactured by Porous Materials Inc.

[0086] thickness

[0087] The samples were measured using a LS-7010M digital micrometer from Keyence.

[0088] The present invention has now been described in some detail for purposes of clarity and understanding. However, it will be apparent to those skilled in the art that certain changes and modifications may be practiced within the scope of the appended claims.

[0089] In the foregoing description, for purposes of explanation, numerous details have been set forth to provide an understanding of various embodiments of the present invention. However, it will be apparent to one skilled in the art that certain embodiments may be practiced without some of these specific details, or with additional details.

[0090] Although certain embodiments have been described, those skilled in the art will recognize that various modifications, alternative structures, and equivalents may be made without departing from the spirit of the embodiments. Furthermore, many known methods and components have not been described to avoid unnecessarily obscuring the present invention. Therefore, the foregoing description should not be construed as limiting the present invention or the scope of the claims.

[0091] When a numerical range is provided, it should also be considered to specifically disclose each intermediate value between the upper and lower limits of the range, separated by the smallest fraction of the unit of the lower limit, unless the context clearly indicates otherwise. Any narrower range between any specified value or unspecified intermediate value within the stated range and any other stated value or intermediate value within the stated range are covered. The stated range may independently include or exclude the upper and lower limits of these smaller ranges, and the present invention also includes each range of these smaller ranges that does not include a limit, includes any one or two limits, subject to the explicit exclusion of any limit in the stated range. When a stated range includes one or two limits, it also includes a range that excludes any one or two of the limits.

[0092] As used herein and in the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly indicates otherwise. Furthermore, when used in this specification and the appended claims, the words "comprises," "including," "contains," "has," "having," and "have" are intended to indicate the presence of stated features, integers, steps, or components, but do not preclude the presence or addition of one or more other features, integers, steps, or components, or combinations thereof.

[0093] Hereinafter, other examples are described to facilitate understanding of the present disclosure:

[0094] E1. An acoustic enclosure for an acoustic device, the enclosure comprising: an expanded fluoropolymer membrane having a microstructure comprising tortuous fibrils, wherein the expanded fluoropolymer membrane has an acoustic insertion loss of less than 6 dB at 1 kHz and a water entry pressure (WEP) of at least 9.8 kPa.

[0095] E2. The cover as described in Example 1, wherein the expanded fluoropolymer film is 2 Have an ATEQ airflow rate of at least 10 L / hour.

[0096] E3. The cover of any of the preceding examples, wherein the expanded fluoropolymer membrane has an acoustic insertion loss of less than 5 dB at 1 kHz.

[0097] E4. The cover of any of the preceding examples, wherein the expanded fluoropolymer membrane has an acoustic insertion loss of less than 4 dB at 1 kHz.

[0098] E5. The cover of any of the preceding examples, wherein the expanded fluoropolymer membrane has an acoustic insertion loss of less than 3 dB at 1 kHz.

[0099] E6. The cover of any of the preceding examples, wherein the expanded fluoropolymer membrane has an acoustic insertion loss of less than 1 dB at 1 kHz.

[0100] E7. The cover of any of the preceding examples, wherein the expanded fluoropolymer film has a viscosity greater than or equal to 6 g / m 2 The surface density and thickness of less than 15μm.

[0101] E8. The cover of any of the preceding examples, wherein the expanded fluoropolymer film has a viscosity greater than or equal to 7 g / m 2 The surface density and thickness of less than 15μm.

[0102] E9. The cover as described in any of the above examples, wherein the expanded fluoropolymer film is 2 Have an ATEQ airflow rate of at least 15 L / hour.

[0103] E10. A waterproof acoustic enclosure for an acoustic device, the enclosure comprising: a retractable membrane material having an acoustic loss of less than 6 dB at 1 kHz and a WEP of at least 9.8 kPa.

[0104] E11. The cover as described in Example 10, wherein the shrink film material is 2 Have an ATEQ airflow rate of at least 10 L / hour.

[0105] E12. The cover according to any of the preceding examples, wherein the area ratio of the retraction film material to the initial area of ​​the precursor film is less than 0.75:1.

[0106] E13. The cover as described in any of the above examples, wherein the shrink film material has a thickness of at least 6.9 g / m 2 The unit area mass and thickness of less than 16μm.

[0107] E14. The cover according to any of the preceding examples, wherein the retractable film material is breathable.

[0108] E15. The cover according to any one of the preceding examples, wherein the shrink film material comprises a heat shrink film.

[0109] E16. The cover of any of Examples 1-14, wherein the retractable film material comprises a solvent retractable material.

[0110] E17. The cover according to any of the preceding examples, wherein the retraction film material has an area ratio of less than 75% of the associated precursor film.

[0111] E18. The cover of any of the preceding examples, wherein the retraction film material comprises an expanded fluoropolymer film.

[0112] E19. The cover according to any one of the preceding examples, wherein the retraction film material has a microstructure comprising tortuous fibrils.

[0113] E20. A protective cover assembly for an acoustic device, the assembly comprising: a shell having an opening for transmitting sound waves between the outside of the shell and an acoustic cavity therein; and an acoustic membrane connected to the shell and separating the acoustic cavity from the outside of the shell, wherein the retracted membrane, such as the acoustic membrane, has an acoustic insertion loss of less than 6 dB at 1 kHz and a water entry pressure (WEP) of at least 9.8 kPa.

[0114] E21. The assembly as described in Example 20, wherein the acoustic membrane is 2 Have an ATEQ airflow rate of at least 10 L / hour.

[0115] E22. An assembly as described in any of the preceding examples, wherein the acoustic membrane has an acoustic insertion loss of less than 5 dB at 1 kHz.

[0116] E23. An assembly as described in any of the preceding examples, wherein the acoustic membrane comprises an expanded fluoropolymer membrane.

[0117] E24. An assembly as described in any of the preceding examples, wherein the acoustic membrane comprises an ePTFE membrane.

[0118] E25. An assembly as described in any of the preceding examples, wherein the acoustic membrane comprises a retracted membrane material having an area ratio of less than 75% of the associated precursor membrane.

[0119] E26. An assembly as described in any of the preceding examples, wherein the acoustic membrane material is heat shrinkable.

[0120] E27. An assembly as described in any of Examples 20-25, wherein the acoustic membrane material is solvent retractable.

[0121] E28. An assembly as described in any of the preceding examples, wherein the acoustic membrane has a microstructure comprising tortuous fibrils.

[0122] E29. The component as described in any of the above examples further includes an acoustic device connected to the above-mentioned acoustic cavity, and the above-mentioned acoustic device is capable of generating sound waves and / or receiving sound waves.

Claims

1. An acoustic enclosure for an acoustic device, the acoustic enclosure being configured to be connected to the acoustic device, the enclosure comprising: A shrink film material having a water entry pressure (WEP) of at least 9.8 kPa and an acoustic insertion loss of less than 6 dB at 1 kHz, the shrink film material having a microstructure comprising meander fibrils, the meander fibrils comprising a plurality of fibrils that bend or fold in one direction and then bend or fold in another direction, the width of the meander fibrils being equal to or less than 1.0 micron, the thickness of the shrink film material being equal to or less than 12 microns, and the shrink film material having a microstructure comprising a meander fibril that bends or folds in one direction and then bends or folds in another direction, the ... 2 an ATEQ airflow rate of at least 15 L / hour, wherein the retracted film material refers to a film material that has undergone retraction; The area ratio of the shrinkage film material to the area of ​​the film before shrinkage is less than 0.75:

1.

2. The cover of claim 1, wherein the retracted membrane material has an acoustic insertion loss of less than 5 dB at 1 kHz.

3. The cover according to claim 1 or 2, wherein the shrink film material has a g / m 2 Surface density.

4. The cover of claim 1 or 2, wherein the cover is waterproof.

5. The cover according to claim 1 or 2, wherein: The shrink film material has a thickness of at least 6.9 g / m 2 Mass per unit area.

6. The cover according to claim 1, wherein The shrink film material is breathable.

7. The cover according to claim 1, wherein The shrink film material has been shrunk by heat shrinking.

8. The cover according to claim 1, wherein The shrink film material has been shrunk by solvent shrinkage.

9. The cover according to claim 1, wherein The shrinkage film material is an expanded fluoropolymer film material that has been shrunk.

10. A protective cover assembly for an acoustic device, the protective cover being configured to be connected to the acoustic device, the assembly comprising: a housing having an opening for transmitting sound waves between an exterior of the housing and an acoustic cavity therein; as well as A shrink film having a water entry pressure (WEP) of at least 9.8 kPa and an acoustic insertion loss of less than 6 dB at 1 kHz, the shrink film having a microstructure comprising meander fibrils, the meander fibrils comprising a plurality of fibrils that bend or flex in one direction and then bend or flex in another direction, the width of the meander fibrils being equal to or less than 1.0 micron, the thickness of the shrink film being equal to or less than 12 microns, and the shrink film having a microstructure comprising a meander fibril that bends or flexes in one direction and then bends or flexes in another direction, the microstructure comprising a meander fibril that bends or flexes in one direction and then bends or flexes in another direction, the microstructure comprising a meander fibril that bends or flexes in one direction and then again ... 2 an ATEQ airflow rate of at least 15 L / hour, wherein the retracted film refers to a film that has undergone retraction; The area ratio of the shrunk film to the area of ​​the film before shrinkage is less than 0.75:

1.

11. The assembly of claim 10, further comprising: An acoustic device connected to the acoustic cavity, wherein the acoustic device is capable of generating sound waves and / or receiving sound waves.

12. An acoustic enclosure for an acoustic device, the acoustic enclosure being configured to be connected to the acoustic device, the enclosure comprising: A retracted fluoropolymer film having a microstructure comprising meandering fibrils, the retracted fluoropolymer film having a water entry pressure (WEP) of at least 9.8 kPa and an acoustic insertion loss of less than 6 dB at 1 kHz, the meandering fibrils comprising a plurality of fibrils that bend or flex in one direction and then bend or flex in another direction, the width of the meandering fibrils being equal to or less than 1.0 micrometer, the thickness of the retracted fluoropolymer film being equal to or less than 12 micrometers, the retracted fluoropolymer film having a water entry pressure (WEP) of at least 9.8 kPa and an acoustic insertion loss of less than 6 dB at 1 kHz. 2 an ATEQ airflow rate of at least 15 L / hour, the retracted fluoropolymer film meaning a fluoropolymer film that has undergone retraction; The area ratio of the retracted fluoropolymer film relative to the area of ​​the film before retraction is less than 0.75:1.

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