PATENT DOCUMENT

Publication Number: US-10034073-B2
Application Number: US-201615192817-A
Country: US
Kind Code: B2

Title: Device having a composite acoustic membrane

Abstract:
An electronic device having a composite acoustic membrane to inhibit water ingress and to allow sound transmission, is disclosed. Embodiments include an electroacoustic transducer within an encased space of a casing, and a composite acoustic membrane between the electroacoustic transducer and an acoustic port in the casing. The acoustic membrane may include a nonporous region at least partly covering the acoustic port, and a porous region to vent the electroacoustic transducer volume to the encased space and/or to an environment surrounding the casing. Other embodiments are also described and claimed.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a casing separating an encased space from a surrounding environment, wherein the casing includes an acoustic port; 
 an electroacoustic transducer within the encased space, the electroacoustic transducer having an enclosure wall, wherein a transducer volume is between the enclosure wall and the acoustic port; and 
 an acoustic membrane covering the acoustic port, wherein the acoustic membrane includes
 a nonporous region at least partly covering the acoustic port, wherein the nonporous region is air impermeable, and wherein the nonporous region is acoustically transparent, and 
 a porous region in fluid communication with the transducer volume, wherein the porous region is air permeable, and wherein the porous region is acoustically opaque compared to the nonporous region. 
 
 
     
     
       2. The electronic device of  claim 1 , wherein the nonporous region surrounds the porous region. 
     
     
       3. The electronic device of  claim 2 , wherein the porous region includes an air permeable channel between the transducer volume and one or more of the acoustic port or the encased space. 
     
     
       4. The electronic device of  claim 3 , wherein the porous region is symmetrically arranged about an axis of symmetry extending through the acoustic port. 
     
     
       5. The electronic device of  claim 1  further comprising a protective barrier covering the acoustic port between the surrounding environment and the acoustic membrane. 
     
     
       6. The electronic device of  claim 5  further comprising a spacer between the protective barrier and the acoustic membrane, wherein a protective gap is between the protective barrier and the acoustic membrane. 
     
     
       7. The electronic device of  claim 1 , wherein the electroacoustic transducer includes a microphone having a diaphragm within the transducer volume. 
     
     
       8. An electroacoustic transducer component, comprising:
 an electroacoustic transducer including an enclosure wall; and 
 an acoustic membrane mounted on the enclosure wall, the acoustic membrane including
 a nonporous region, wherein the nonporous region is air impermeable, and 
 
 wherein the nonporous region is acoustically transparent, and
 a porous region, wherein the porous region is air permeable, and wherein the porous region is acoustically opaque compared to the nonporous region; 
 
 wherein a transducer volume is between the acoustic membrane and the enclosure wall, and wherein the transducer volume is in fluid communication with a surrounding environment through the porous region. 
 
     
     
       9. The electroacoustic transducer component of  claim 8 , wherein the nonporous region surrounds the porous region. 
     
     
       10. The electroacoustic transducer component of  claim 9 , wherein the porous region is symmetrically arranged about an axis of symmetry orthogonal to a front surface of the acoustic membrane. 
     
     
       11. The electroacoustic transducer component of  claim 8  further comprising a protective barrier covering the acoustic membrane. 
     
     
       12. The electroacoustic transducer component of  claim 11  further comprising a spacer between the protective barrier and the acoustic membrane, wherein a protective gap is between the protective barrier and the acoustic membrane. 
     
     
       13. The electroacoustic transducer component of  claim 8 , wherein the electroacoustic transducer includes a microphone having a diaphragm within the transducer volume. 
     
     
       14. A method, comprising:
 providing a densified acoustic membrane having a nonporous region and a porous region; wherein the nonporous region is acoustically transparent and the porous region is acoustically opaque compared to the nonporous region; 
 providing an electroacoustic transducer having an enclosure wall and a transducer volume; and 
 mounting the densified acoustic membrane on the electroacoustic transducer in such a manner that the porous region of the mounted densified membrane faces the transducer volume between the densified acoustic membrane and a front side of the enclosure wall. 
 
     
     
       15. The method of  claim 14  further comprising:
 providing a casing; and 
 the mounting comprising mounting the acoustic membrane on the casing, wherein the nonporous region at least partly covers an acoustic port in the casing. 
 
     
     
       16. The method of  claim 15 , wherein the porous region includes an air permeable channel positioned between the transducer volume and the acoustic port. 
     
     
       17. The method of  claim 15 , wherein the porous region includes an air permeable channel positioned between the transducer volume and an encased space between a back side of the enclosure wall and the casing. 
     
     
       18. The method of  claim 14 , wherein the densified acoustic membrane includes a deformed acoustic membrane. 
     
     
       19. The method of  claim 14 , wherein the electroacoustic transducer includes a microphone having a diaphragm within the transducer volume. 
     
     
       20. The method of  claim 14  further comprising: mounting a protective barrier on a spacer; and mounting the spacer on the densified acoustic membrane to form a protective gap between the protective barrier and the densified acoustic membrane. 
     
     
       21. An electronic device, comprising:
 a casing separating an encased space from a surrounding environment, wherein the casing includes an acoustic port; 
 an electroacoustic transducer within the encased space, the electroacoustic transducer having an enclosure wall, wherein a transducer volume is between the enclosure wall and the acoustic port; and 
 an acoustic membrane covering the acoustic port, wherein the acoustic membrane includes
 a nonporous region at least partly covering the acoustic port, wherein the nonporous region is air impermeable, and 
 a porous region in fluid communication with the transducer volume, wherein the porous region is air permeable, and wherein the porous region is thicker than the nonporous region. 
 
 
     
     
       22. The electronic device of  claim 21 , wherein the nonporous region surrounds the porous region. 
     
     
       23. The electronic device of  claim 21  further comprising a protective barrier covering the acoustic port between the surrounding environment and the acoustic membrane. 
     
     
       24. The electronic device of  claim 21 , wherein the electroacoustic transducer includes a microphone having a diaphragm within the transducer volume.

Description:
This application claims the benefit of U.S. Provisional Patent Application No. 62/201,069, filed Aug. 4, 2015, and this application hereby incorporates herein by reference that provisional patent application in its entirety. 
    
    
     BACKGROUND 
     Field 
     Embodiments related to electronic devices having water resistant barriers are disclosed. More particularly, embodiments related to electronic devices having water resistant membranes are disclosed. 
     Background Information 
     An electronic device, such as a computer and/or mobile device, may be exposed to water, e.g., rain or water in a swimming pool. Porous membranes are used to protect electronic components within such electronic devices from particle or water ingress. Such membranes may also allow air exchange between an environment surrounding the electronic device and an enclosed volume within the electronic device. Air exchange across the barrier may be important when ambient pressure swings, e.g., from changes in altitude, can impact the function of an electronic device and device components. For example, a pressure difference across the barrier may cause the barrier to stretch and become effectively stiffer, which may impact acoustic transparency in the case of microphone or speaker barriers, and could damage or break the barrier. Thus, in water resistant applications, porous barriers are typically used. 
     SUMMARY 
     Porous barriers used to reduce the likelihood of water ingress are typically acoustically inferior to nonporous membranes of equal water resistance due to a required increase in thickness of the porous membrane. That is, a nonporous barrier can withstand higher water pressure than a porous barrier of equal thickness, and thus, a nonporous barrier to prevent water ingress may be thinner than a porous barrier with comparable water resistance, e.g., resistance to 5 bar water pressure. A nonporous barrier, however, may be gas impermeable, requiring another mechanism of air exchange for barometric relief. 
     An electronic device may benefit from a membrane that inhibits water ingress, allows gas exchange for pressure equalization, e.g., allows venting of air from an electroacoustic transducer on another side of the membrane for barometric relief, and is acoustically transparent. Such a membrane may be considered to be an acoustic membrane because at least a portion of the membrane may be acoustically transparent. For example, the acoustic membrane may include a nonporous region that prevents water ingress and transfers acoustic energy. Furthermore, at least a portion of the membrane may be acoustically opaque. For example, the acoustic membrane may include a porous region that prevents water ingress and provides barometric venting, yet includes a reactive resistance that inhibits the transfer of acoustic energy. 
     In an embodiment, an electronic device having a composite acoustic membrane performs well acoustically and has good water resistance. The electronic device may include a casing separating an encased space from a surrounding environment, and an electroacoustic transducer, e.g., a microphone, within the encased space. More particularly, the electroacoustic transducer may have an enclosure wall such that a transducer volume is defined between the enclosure wall and an acoustic port in the casing. A composite acoustic membrane may be between the acoustic port and the transducer volume to provide acoustic transmission and/or venting between the surrounding environment and the transducer volume. More particularly, the composite acoustic membrane may include a nonporous region covering the acoustic port, and the nonporous region may be air impermeable and acoustically transparent to transmit sound. Furthermore, the acoustic membrane may include a porous region in fluid communication with the transducer volume, and the porous region may be air permeable (and water impermeable) and acoustically opaque. Accordingly, the composite acoustic membrane may transmit sound toward the electroacoustic transducer, vent air from the transducer volume, and prevent water from entering the transducer volume. 
     The electronic device may include other features, such as a protective barrier covering the acoustic port to protect the acoustic membrane. For example, the protective barrier may include a mesh between the surrounding environment and the acoustic membrane to protect the membrane from puncture. A spacer may be placed between the protective barrier and the acoustic membrane to form a protective gap between the protective barrier and the acoustic membrane. As such, the protective barrier may flex, e.g., when an object is inserted into the acoustic port, without contacting and damaging the acoustic membrane. 
     The composite acoustic membrane may be used in the electronic device as described above, and the composite acoustic membrane may be included as a portion of an electroacoustic transducer component. More particularly, the acoustic membrane may be mounted on the enclosure wall of the electroacoustic transducer to form the electroacoustic transducer component, which may be integrated into the electronic device. 
     In an embodiment, a method of manufacturing the electronic device or the electroacoustic transducer includes densifying a porous membrane to form the acoustic membrane having the porous region and a densified region, e.g., the nonporous region. The acoustic membrane may be mounted on an electroacoustic transducer and/or a casing of an electronic device such that the porous region of the acoustic membrane faces the transducer volume and the nonporous region of the acoustic membrane at least partly covers the acoustic port in the casing. Accordingly, the acoustic membrane may be integrated in the electronic device to transmit sound into the transducer volume and/or vent air from the transducer volume. 
     The above summary does not include an exhaustive list of all aspects of the present invention. It is contemplated that the invention includes all systems and methods that can be practiced from all suitable combinations of the various aspects summarized above, as well as those disclosed in the Detailed Description below and particularly pointed out in the claims filed with the application. Such combinations have particular advantages not specifically recited in the above summary. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a pictorial view of an electronic device in accordance with an embodiment. 
         FIG. 2  is a schematic view of an electronic device in accordance with an embodiment. 
         FIG. 3A  is a front view of a composite acoustic membrane in accordance with an embodiment. 
         FIG. 3B  is a front view of a composite acoustic membrane in accordance with an embodiment. 
         FIG. 4  is a sectional view, taken about line A-A of  FIG. 3A , of a composite acoustic membrane in accordance with an embodiment. 
         FIG. 5  is a sectional view of an electronic device having a composite acoustic membrane in accordance with an embodiment. 
         FIG. 6  is a detailed sectional view, taken from Detail A of  FIG. 5 , of an electronic device having a composite acoustic membrane in accordance with an embodiment. 
         FIG. 7  is a sectional view of an electronic device having a composite acoustic membrane in accordance with an embodiment. 
         FIG. 8  is a detailed sectional view, taken from Detail B of  FIG. 7 , of an electronic device having a composite acoustic membrane in accordance with an embodiment. 
         FIG. 9  is a sectional view of an electronic device having a composite acoustic membrane in accordance with an embodiment. 
         FIG. 10  is a flowchart of a method of making an electronic device having a composite acoustic membrane in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments describe electronic devices and/or electroacoustic transducer components having a composite acoustic membrane that reduces the likelihood of water ingress from a surrounding environment, transfers acoustic energy between the surrounding environment and an electroacoustic transducer, and vents air from an active region of the electroacoustic transducer to the surrounding environment and/or a space within the electronic device. Some embodiments are described with specific regard to integration within mobile devices such as mobile phones. The embodiments are not so limited, however, and certain embodiments may also be applicable to other uses. For example, a composite acoustic membrane may be incorporated into other devices and apparatuses, including desktop computers, laptop computers, tablet computers, wearable computers, wristwatch devices, or motor vehicles, to name only a few possible applications. 
     In various embodiments, description is made with reference to the figures. Certain embodiments, however, may be practiced without one or more of these specific details, or in combination with other known methods and configurations. In the following description, numerous specific details are set forth, such as specific configurations, dimensions, and processes, in order to provide a thorough understanding of the embodiments. In other instances, well-known processes and manufacturing techniques have not been described in particular detail in order to not unnecessarily obscure the description. Reference throughout this specification to “one embodiment,” “an embodiment,” or the like, means that a particular feature, structure, configuration, or characteristic described is included in at least one embodiment. Thus, the appearance of the phrase “one embodiment,” “an embodiment,” or the like, in various places throughout this specification are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, configurations, or characteristics may be combined in any suitable manner in one or more embodiments. 
     The use of relative terms throughout the description, such as “in front of” and “behind” may denote a relative position or direction. For example, an acoustic membrane may be described as being “behind” a port in a casing when it is on an opposite side of the port from a surrounding environment, i.e., when the surrounding environment is “in front of” of the port. Nonetheless, such terms are not intended to limit the use of an acoustic membrane to a specific configuration described in the various embodiments below. For example, an acoustic membrane may be located on the same side of the port as the surrounding environment. 
     In an aspect, an electronic device includes a composite acoustic membrane having a porous region and a nonporous region. The porous region may be water resistant and allow air exchange for pressure equalization. The nonporous region may be water resistant and acoustically transparent. Thus, the composite acoustic membrane may inhibit water ingress, vent an acoustically active region of an electronic device, and transmit sound from a surrounding environment to an electroacoustic transducer component within the electronic device. 
     Referring to  FIG. 1 , a pictorial view of an electronic device is shown in accordance with an embodiment. An electronic device  100  may be a smartphone device. Alternatively, it could be any other portable or stationary device or apparatus, such as a laptop computer, a tablet computer, a wearable computer, a wristwatch device, etc. Electronic device  100  may include various capabilities to allow the user to access features involving, for example, calls, voicemail, music, e-mail, internet browsing, scheduling, or photos. Electronic device  100  may also include hardware to facilitate such capabilities. For example, a casing  102  may contain a microphone  104  to pick up the voice of a user during a call, and an audio speaker  106 , e.g., a micro speaker, to deliver a far-end voice to the near-end user during the call. Speaker  106  may also emit sounds associated with music files played by a music player application running on electronic device  100 . A display  108  may present the user with a graphical user interface to allow the user to interact with electronic device  100  and/or applications running on electronic device  100 . Other conventional features are not shown but may of course be included in electronic device  100 . 
     Referring to  FIG. 2 , a schematic view of an electronic device is shown in accordance with an embodiment. As described above, electronic device  100  may be one of several types of portable or stationary devices or apparatuses with circuitry suited to specific functionality. Accordingly, the diagrammed circuitry is provided by way of example and not limitation. Electronic device  100  may include one or more processors  202  to execute instructions to carry out the different functions and capabilities described above. Instructions executed by processor(s)  202  of electronic device  100  may be retrieved from a local memory  204 , and may be in the form of an operating system program having device drivers, as well as one or more application programs that run on top of the operating system. The instructions may cause electronic device  100  to perform the different functions introduced above, e.g., phone and/or music play back functions. To perform such functions, processor(s)  202  may directly or indirectly implement control loops and receive input signals from and/or provide output signals to other electronic components, such as microphone  104  or speaker  106 . 
     Referring to  FIG. 3A , a front view of a composite acoustic membrane is shown in accordance with an embodiment. That is, the front view may be of a front surface of a composite acoustic membrane  300 . In an embodiment, acoustic membrane  300  may be incorporated in electronic device  100  as a water resistant barrier between microphone  104  and/or speaker  106  and an environment surrounding electronic device  100 . Acoustic membrane  300  may include several distinct regions. For example, acoustic membrane  300  may include a porous region  302 , a nonporous region  304 , and optionally, a substrate region  306 . Acoustic membrane  300  and the various regions of acoustic membrane  300  may have different shapes in various embodiments. 
     In an embodiment, acoustic membrane  300  includes a membrane perimeter  308  surrounding the regions of the membrane. The membrane perimeter  308  may be rectangular, or any other shape, e.g., circular, polygonal, etc. Nonporous region  304  may be centrally located relative to membrane perimeter  308 . For example, nonporous region  304  may be disposed along an axis of symmetry  310  orthogonal to the front surface of acoustic membrane  300  (coming out of the page in  FIG. 3A ). In an embodiment, porous region  302  is symmetrically arranged about axis of symmetry  310 . Furthermore, nonporous region  304  may include a shape defined by an inner edge of porous region  302 . For example, porous region  302  may have an annular shape, and thus, may include an inner circular perimeter and an outer circular perimeter separated by an annulus width. The inner circular perimeter may surround nonporous region  304  such that nonporous region  304  has a circular area. The annular porous region  302  may be centered on axis  310 , and thus, the circular area may be centered on axis  310 . 
     Substrate region  306  may be disposed outside of an outer edge of porous region  302 . For example, when porous region  302  includes an outer circular perimeter, substrate region  306  may be defined as the portion of acoustic membrane  300  between the outer circular perimeter and membrane perimeter  308 . Substrate region  306  may be nonporous, and thus, may be a portion of nonporous region  304 . Accordingly, nonporous region  304  may surround porous region  302 . Substrate region  306  and nonporous region  304  may have a same or different porosity, and may both be air impermeable. In an embodiment, however, substrate region  306  may be acoustically opaque and nonporous region  304  may be acoustically transparent, or vice versa. 
     Referring to  FIG. 3B , a front view of a composite acoustic membrane is shown in accordance with an embodiment. In an embodiment, porous region  302  may not surround nonporous region  304 . For example, nonporous region  304  may be defined as any region within membrane perimeter  308  that is not occupied by porous region  302 . More particularly, acoustic membrane  300  may include nonporous region  304  extending across the membrane area between opposite sides of membrane perimeter  308 , and nonporous region  304  may surround one or more porous regions  302 . Here, the term “surround” is used to describe nonporous region  304  extending around sidewalls of porous region  302  within a plane parallel to the front surface of acoustic membrane  300 . That is, nonporous region  304  and porous region  302  may have exposed (uncovered) front and back surfaces. Accordingly, an outer edge of nonporous region  304  may coincide with membrane perimeter  308 . Furthermore, porous region  302  may include several noncontiguous segments, such as two straight bars offset on opposite sides of the axis of symmetry  310  of acoustic membrane  300 . The bars may be symmetric about, e.g., mirrored relative to, axis of symmetry  310 . Porous region  302  and/or segments of porous region  302  may be shaped in any manner, including as arc segments, as angular segments, or as any other shape that is surrounded by nonporous region  304 . In an embodiment, nonporous region  304  is intersected by the axis of symmetry  310 . 
     In an embodiment, a surface area of porous region  302  may be less than a surface area of nonporous region  304 . For example, nonporous region  304  may include a surface area that is at least 10% greater, e.g., more than 50% greater, than a surface area of porous region  302 . Furthermore, nonporous region  304  may occupy a proportionally larger percentage of a total surface area of acoustic membrane  300 , as compared to porous region  302 . For example, porous region  302  may occupy not more than 25% of the total surface area, and nonporous region  304  may occupy more than 25% of the total surface area. 
     Referring to  FIG. 4 , a sectional view, taken about line A-A of  FIG. 3 , of a composite acoustic membrane is shown in accordance with an embodiment. In an embodiment, porous region  302  is air permeable. That is, porous region  302  may include air permeable channels  404  to allow air to pass from one side of acoustic membrane  300  to another side of acoustic membrane  300 . For example, air permeable channels  404  may have a mean cross-sectional dimension greater than the mean free path of air at ambient pressure, e.g., greater than 70 nm. Thus, air permeable channels  404  may pass air across acoustic membrane  300 . This air transfer may provide gas exchange across acoustic membrane  300  to provide pressure equalization between regions on opposite sides of acoustic membrane  300 . By contrast, nonporous region  304  of acoustic membrane  300  may be air impermeable. That is, nonporous region  304  may include air impermeable channels  402 . Air impermeable channels  402  may have a mean cross-sectional dimension less than the mean free path of air at ambient pressure, e.g., less than 50 nm. Thus, air impermeable channels  402  may inhibit the passage of air across acoustic membrane  300 , and reduce the likelihood of gas exchange between regions located on opposite sides of acoustic membrane  300 . 
     In an embodiment, nonporous region  304  may be acoustically transparent and porous region  302  may be acoustically opaque. More particularly, nonporous regions  304  may include a reactive resistance below a predetermined acoustic transparency threshold and porous region  302  may include a reactive resistance above a predetermined acoustic opacity threshold. For example, the acoustic transparency threshold may refer to nonporous region  304  having an acoustic loss of less than 6 decibel when impacted by longitudinal sound waves, e.g., an acoustic loss of less than 1 decibel. By contrast, the acoustic opacity threshold may refer to porous region  302  having an acoustic loss of more than 6 decibel when impacted by longitudinal sound waves, e.g., an acoustic loss of more than 10 decibel. Accordingly, nonporous region  304  may deflect sufficiently under the pressure of the longitudinal sound waves to compress air and direct sound to an active region of an electroacoustic transducer  506 , and nonporous region  304  may not deflect sufficiently under the pressure to transmit such sound. 
     The relative acoustic transparency and/or opacity of the different regions of a composite acoustic membrane  300  may depend on the thickness and density of the regions. For example, as described below, porous region  302  and nonporous region  304  may begin as a same bulk substrate material, e.g., a porous substrate, and a portion of the bulk substrate material may be densified to form nonporous region  304 . Thus, respective cross-sections taken axially through nonporous region  304  and porous region  302  may have a same mass, but nonporous region  304  may be denser then porous region  302 . Accordingly, porous region  302  may have a greater volume than nonporous regions  304 , and portions of acoustic membrane  300  having air permeable channels  404  may be thicker than portions of acoustic membrane  300  having air impermeable channels  402 . In an embodiment, the thicker porous regions  302  may have higher reactive resistance, causing the porous regions  302  to be acoustically opaque. By contrast, the thinner nonporous regions  304  may have lower reactive resistance, causing the nonporous regions  304  to be acoustically transparent. 
     Referring to  FIG. 5 , a sectional view of an electronic device having a composite acoustic membrane is shown in accordance with an embodiment. Casing  102  may include a casing wall  502  having an outer surface defining exterior contours of electronic device  100  and an inner surface enclosing an encased space  504  of electronic device  100 . One or more electronic components may be housed within encased space  504 . For example, electronic device  100  may include an electroacoustic transducer component  506 , e.g., microphone  104 , connected to the inner surface of casing  102  at a first location within encased space  504 . Speaker  106  may be located at a second location within encased space  504 . Speaker  106  is shown generically in  FIG. 5 , but it will be appreciated that the speaker  106  may be one of different types of speakers, e.g., the speaker  106  may include an open or closed-back speaker. Casing  102  may surround the encased components of electronic device  100  and separate the electronic components from a surrounding environment  508 . Furthermore, casing  102  may enclose other components of electronic device  100 , e.g., electronic circuitry associated with the various components described above with respect to  FIG. 2 . 
     Casing  102  may separate encased space  504  from surrounding environment  508 , however, one or more openings may be disposed in the casing wall  502  to place the encased space  504  in fluid communication with the surrounding environment  508 . More particularly, apertures may be located between surrounding environment  508  and one or more portions of encased space  504 . For example, an acoustic port  510  may be disposed in casing  102  between surrounding environment  508  and a transducer volume  512 , i.e., an active volume of an electroacoustic transducer  506 . Transducer volume  512  may be a portion, i.e., a sub-volume, of encased space  504 . More particularly, transducer volume  512  may be the space between an enclosure wall  514  of electroacoustic transducer  506 , e.g., microphone  104 , and the inner surface of casing  102 . More particularly, transducer volume  512  may be between enclosure wall  514  and acoustic port  510 . 
     In an embodiment, one or more of the openings may be covered by a barrier having water resistance characteristics and acoustic characteristics. For example, acoustic membrane  300  may cover acoustic port  510 . As described above, acoustic membrane  300  may be a composite acoustic membrane having porous region  302  and nonporous region  304 . Accordingly, porous region  302  and nonporous region  304  of acoustic membrane  300  may provide water resistant characteristics to acoustic port  510 , and nonporous region  304  of acoustic membrane  300  may provide acoustic characteristics to acoustic port  510 . Here, acoustic characteristics refers to the acoustic transparency of nonporous regions  304 . More particularly, longitudinal sound waves that impact the nonporous regions  304  may deflect acoustic membrane  300  sufficiently to compress air and transmit sound to an active region of an electroacoustic transducer  506 , e.g., microphone  104  or an electrodynamic speaker  106 , located behind acoustic port  510 . 
     Some ports in casing  102  may be uncovered. More particularly, some ports may provide open channels, i.e., non-acoustically resistant channels, between surrounding environment  508  and encased space  504  or a component located within encased space  504 . For example, speaker  106  may be located within encased space  504  behind a speaker port  515 . Speaker port  515  may be uncovered, and thus, may provide a water ingress point between surrounding environment  508  and a portion of speaker  106  that is located behind speaker port  515 . The exposed portion of speaker  106 , however, may have a water resistant construction and/or may include a water resistant component, e.g., a sealed speaker diaphragm that is in direct contact with the incoming water. Thus, water ingress into encased space  504  may be inhibited. In an embodiment, speaker port  515  may be covered by a membrane, e.g., acoustic membrane  300 , to provide water resistance and transmit sound toward surrounding environment  508 . 
     One or more ports in casing  102  may be covered by a membrane having only water resistant characteristics or only acoustic characteristics. For example, a vent port  516  may be disposed in casing  102  between surrounding environment  508  and encased space  504 . Vent port  516  may function, for example, to equalize pressure between encased space  504  and surrounding environment  508 . That is, vent port  516  may provide a barometric vent between encased space  504  and surrounding environment  508 . Some components of electronic device  100 , such as microphone  104  or speaker  106 , may affect the air pressure within encased space  504 . Vent port  516  in casing  102  may accommodate such pressure fluctuations, and maintain pressure equilibrium between encased space  504  and surrounding environment  508 . A vent membrane  518  may cover vent port  516  to provide a barrier against water ingress through vent port  516 . Thus, vent membrane  518  may be formed to include material properties, e.g., porosity, similar to porous region  302  of acoustic membrane  300  such that vent membrane  518  exhibits water resistant and gas exchange characteristics, but not acoustic characteristics. 
     Referring to  FIG. 6 , a detailed sectional view, taken from Detail A of  FIG. 5 , of an electronic device having a composite acoustic membrane is shown in accordance with an embodiment. Microphone  104  may be mounted on the inner surface of casing  102 . For example, enclosure wall  514  may be attached to the inner surface by a pressure sensitive adhesive bond, or another manner of attachment. Thus, transducer volume  512  may be separated from encased space  504  by enclosure wall  514 . Sub-components of microphone  104 , such as a diaphragm  602 , may be disposed within transducer volume  512 . The functionality of microphone  104 , e.g., the sensitivity of diaphragm  602  to external sounds, may be enhanced by isolating transducer volume  512  from water outside of microphone  104  and by facilitating barometric relief of pressure generated within transducer volume  512 . 
     In an embodiment, acoustic port  510  is covered by acoustic membrane  300  having regions that selectively repel water while allowing air to be freely exchanged between surrounding environment  508  and transducer volume  512 . More particularly, a portion of acoustic membrane  300  facing acoustic port  510 , i.e., covering acoustic port  510 , may have a porosity that does not allow water ingress. For example, porous region  302  and nonporous region  304  of acoustic membrane  300  exposed to the opening of acoustic port  510  may form a barrier against water such that water traveling along a water path  604  toward acoustic membrane  300  is repelled outward and away from transducer volume  512 . By contrast, porous region  302  of acoustic membrane  300  may have a porosity that allows air to travel across a thickness of acoustic membrane  300 , and thus, air may move freely along an air path  606  between surrounding environment  508  and transducer volume  512 . That is, porous region  302  may vent air within transducer volume  512  to surrounding environment  508 . Porous region  302  may thus be considered to be in fluid communication with transducer volume  512  because a gas, e.g., air, can pass through porous region  302  to or from transducer volume  512 , even though a liquid, e.g., water, may not. Accordingly, microphone  104  components within transducer volume  512  may be protected against water ingress and air pressure within transducer volume  512  may be equalized with the air pressure outside of casing  102  to facilitate microphone sensitivity. 
     A total surface area of porous regions  302  exposed to acoustic port  510  may be comparatively smaller than a total surface area of nonporous regions  304  exposed to acoustic port  510 . For example, the total surface area of the porous region  302  may be less than 20%, e.g., less than 10%, of the total surface area of nonporous region  304  exposed to acoustic port  510 . Accordingly, the area of acoustic membrane  300  exposed to longitudinal sound waves coming from surrounding environment  508  may be mostly acoustically transparent, allowing for effective transfer of sound to an active region of microphone  104  located behind acoustic port  510 . 
     Referring to  FIG. 7 , a sectional view of an electronic device having a composite acoustic membrane is shown in accordance with an embodiment. Electronic device  100  may have a similar structure to that shown in  FIG. 5 . For example, casing  102  may surround several electronic components including an electroacoustic transducer, e.g., microphone  104 , and speaker  106 , and those components may be located within encased space  504  relative to one or more ports. Furthermore, the ports may be covered by membranes having water resistant and/or acoustic characteristics. Thus, the electronic components may be protected against water ingress from surrounding environment  508 . In an embodiment, acoustic membrane may be a composite acoustic membrane  300  having water resistant characteristics and having a structure and arrangement that allows pressure generated within microphone  104  to equalize with pressure in encased space  504 . 
     Referring to  FIG. 8 , a detailed sectional view, taken from Detail B of  FIG. 7 , of an electronic device having a composite acoustic membrane is shown in accordance with an embodiment. Casing  102  may include acoustic port  510  vulnerable to the ingress of water as described above. To prevent such ingress, acoustic membrane  300  may be used to cover acoustic port  510 . In an embodiment, an electroacoustic transducer component  506  is attached to the inner surface of casing  102  to provide such covering. For example, the electroacoustic transducer component  506  may include the subcomponents of microphone  104 , e.g., enclosure wall  514 , diaphragm  602 , etc. Transducer volume  512  of microphone  104  may be disposed between enclosure wall  514  and acoustic membrane  300 . More particularly, enclosure wall  514  may be attached to acoustic membrane  300 . For example, enclosure wall  514  and/or acoustic membrane  300  may include an adhesive  802 , such as a pressure sensitive adhesive (PSA) that bonds and seals the components together. Similarly, acoustic membrane  300  may be attached to the inner wall of casing  102  by an adhesive joint. For example, a PSA may cover a portion of acoustic membrane  300  facing the inner wall such that the electroacoustic transducer  506  component may be pressed against casing  102  to assemble the components. 
     Acoustic membrane  300  of the electroacoustic transducer  506  component may be positioned between acoustic port  510  and transducer volume  512  such that nonporous region  304  of acoustic membrane  300  at least partly covers acoustic port  510 . That is, acoustic membrane  300  may be positioned relative to acoustic port  510  such that nonporous region  304  covers all or most of acoustic port  510 . For example, nonporous region  304  may have a dimension across the face of acoustic membrane  300  that is greater than a cross-sectional dimension of acoustic port  510 . Accordingly, porous region  302  may be entirely behind casing  102 . Furthermore, an adhesive seal may be formed between casing  102  and the front surface of acoustic membrane  300  such that the adhesive seal covers the front surface of porous region  302 . Thus, water moving through acoustic port  510  toward transducer volume  512  may only contact nonporous region  304  of acoustic membrane  300 , i.e., water may be blocked from porous region  302  by adhesive seal. Thus, water path  604  may be directed away from transducer volume  512  to prevent water ingress into transducer volume  512  and encased space  504 . 
     Acoustic membrane  300  of the electroacoustic transducer  506  component may also be positioned relative to acoustic port  510  such that porous regions  302  of acoustic membrane  300  provide air path  606  between transducer volume  512  and encased space  504  on a back side of enclosure wall  514 . For example, a rear surface of acoustic membrane  300  may include porous region  302  facing transducer volume  512  radially inward of enclosure wall  514 . The portion of porous region  302  facing transducer volume  512 , e.g., the distance between nonporous region  304  and the enclosure wall  514 , may be referred to as an overlap region  804 . One skilled in the art will appreciate that when speaker  106  is located in encased space  504 , pressure variations generated during sound reproduction by speaker  106  may propagate through the acoustic path of porous region  302  into transducer volume  512 . Thus, air passage through porous region  302  may be affected, which could impact the microphone response. Accordingly, overlap  804  may be sized to allow air to pass from transducer volume  512  to encased space  504 , however, air passage from encased space  504  to transducer volume  512  may be limited. As an example, overlap  804  may have a distance between enclosure wall  514  (or a radially inward edge of adhesive  802  that seals the rear surface of porous region  302 ) and nonporous region  304  that is less than 0.5 mm. 
     Furthermore, porous region  302  may face encased space  504 , e.g., along an outer edge of acoustic membrane  300  or along the rear surface of acoustic membrane  300  that faces encased space  504  radially outward of enclosure wall  514 . Accordingly, air path  606  may be directed through the interconnected air permeable channels  404  of porous region  302  from transducer volume  512  to encased space  504 . Thus, air pressure within transducer volume  512  may be equalized with air pressure within encased space  504 . 
     Referring to  FIG. 9 , a sectional view of an electronic device having a composite acoustic membrane is shown in accordance with an embodiment. In an embodiment, electronic device  100  may include a protective barrier  902  to prevent puncturing of acoustic membrane  300 . For example, ingress of debris and/or inadvertent insertion of objects into acoustic port  510  may puncture acoustic membrane  300  and damage the electroacoustic transducer  506 . Protective barrier  902  may cover acoustic port  510  and may be located between surrounding environment  508  and acoustic membrane  300 . Accordingly, the electroacoustic transducer component having acoustic membrane  300  and the electroacoustic transducer  506 , e.g., microphone  104 , may be positioned behind protective barrier  902 . Protective barrier  902  may include a material with puncture resistance that can block debris ingress. For example, protective barrier  902  may include a woven acoustic mesh, e.g., a metallic mesh having a predetermined porosity and rigidity. Protective barrier  902  may block debris or objects of a predetermined minimum diameter, e.g., the diameter of a wire forming a paper clip. 
     Protective barrier  902  may flex when pressed, and thus, a protective gap  904  between protective barrier  902  and acoustic membrane  300  may be used to prevent contact between those components. For example, a spacer  906  may be disposed between protective barrier  902  and acoustic membrane  300 . Spacer  906  may have a predetermined thickness such that when protective barrier  902  is pressed with a given force, the deflection of protective barrier  902  is less than protective gap  904  created by spacer  906 . Accordingly, acoustic membrane  300  is physically protected against piercing by protective barrier  902  and spacer  906 . As described above, the components of electronic device  100  may be attached to one another by adhesive bonds, and furthermore, the adhesive bonds may create seals that prevent water and air ingress between the components. Other seals may also be provided. For example, a seal  908  may be formed between spacer  906  and protective barrier  902  outward of the protective mesh such that water ingress into encased space  504  and air egress out of encased space  504  is limited. 
     Referring to  FIG. 10 , a flowchart of a method of making an electronic device having a composite acoustic membrane is shown in accordance with an embodiment. At operation  1002 , a membrane is densified to form acoustic membrane  300 . For example, a porous membrane substrate may be modified to create acoustic membrane  300  having one or more porous regions  302  and one or more densified regions, e.g., nonporous regions  304 . Thus, the membrane substrate may be altered to not only provide water resistance and venting, but to also provide acoustic characteristics. 
     Densifying the porous membrane may include deforming the porous membrane in the densified region. For example, the porous membrane substrate may be densified by stretching. The porous membrane substrate may be a material having a predetermined porosity, e.g., an expanded polytetrafluoroethylene (PTFE), and by stretching the material in a transverse direction, the substrate thickness may be reduced in an axial direction. Reduction in thickness may be accompanied by a corresponding decrease in porosity. Thus, localized areas of the porous membrane substrate may be stretched to form one or more nonporous regions  304  in a composite acoustic membrane  300 . The porous membrane may be densified by crushing. For example, a die may be used to press a localized area of the porous membrane substrate to crush the porous material and reduce the thickness of the membrane. Accordingly, crushing the porous membrane substrate may form one or more nonporous regions  304  in a composite acoustic membrane  300 . Thus, porous membrane may be densified to form an acoustically transparent region, e.g., nonporous region  304 . 
     At operation  1004 , acoustic membrane  300  may be mounted on an electroacoustic transducer  506 , e.g., microphone  104  or speaker  106 . For example, acoustic membrane  300  may be mounted on enclosure wall  514  such that transducer volume  512  is between acoustic membrane  300  and enclosure wall  514 . More particularly, electroacoustic transducer  506  may be positioned with respect to acoustic membrane  300  such that porous region  302  faces transducer volume  512 . Accordingly, transducer volume  512  between acoustic membrane  300  and a front side of enclosure wall  514  may be placed in fluid communication with surrounding environment  508  or encased space  504  through porous region  302 . As such, transducer volume  512  may be vented through porous region  302  of acoustic membrane  300  to surrounding environment  508  or encased space  504 . 
     At operation  1006 , acoustic membrane  300  may be mounted on casing  102  such that the densified region, e.g., nonporous region  304 , is at least partly covering acoustic port  510  in casing  102 . As described above, acoustic membrane  300  may be positioned such that nonporous region  304  entirely covers acoustic port  510 . Thus, air permeable channel  404  of porous region  302  may extend between transducer volume  512  and encased space  504  between a back side of enclosure wall  514  and casing  102 , and air in transducer volume  512  may be vented through acoustic membrane  300  to encased space  504 . Alternatively, acoustic membrane  300  may be positioned such that nonporous region  304  only partly covers acoustic port  510 . Thus, air permeable channel  404  of porous region  302  may extend between transducer volume  512  and acoustic port  510 , and air in transducer volume may be vented through acoustic membrane  300  to surrounding environment  508  through porous region  302 . 
     It will be appreciated that the operations described above may be performed in a different order. For example, acoustic membrane  300  may be mounted on casing  102  prior to being mounted on electroacoustic transducer  506 . When acoustic membrane  300  is mounted on electroacoustic transducer  506  prior to being mounted on casing  102 , an electroacoustic transducer component may be manufactured as a subassembly, which may then be assembled to casing  102  during the manufacture of electronic device  100 . 
     The method of making an electronic device  100  having a composite acoustic membrane  300  may include additional operations not represented in the flowchart of  FIG. 10 . For example, protective barrier  902  may be mounted on spacer  906  in an operation. The spacer  906  may be mounted on acoustic membrane  300  to form protective gap  904  between protective barrier  902  and acoustic membrane  300 . Either of operations  1004  or  1006  may be performed such that protective barrier  902  covers acoustic port  510  to protect acoustic membrane  300  within casing  102 . 
     In the foregoing specification, the invention has been described with reference to specific exemplary embodiments thereof. It will be evident that various modifications may be made thereto without departing from the broader spirit and scope of the invention as set forth in the following claims. The specification and drawings are, accordingly, to be regarded in an illustrative sense rather than a restrictive sense.

Metadata:
Filing Date: 20160624
Publication Date: 20180724
Grant Date: 20180724
Priority Date: 20150804
Inventors: EVANS, NEAL
LIPPERT, Jesse A.
VITT, Nikolas T.
Assignee: APPLE INC
CPC Classifications: [{"code": "H04R2499/11", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04M1/035", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04M1/026", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R2499/11", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R2499/13", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/086", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F1/1656", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R2499/13", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04M1/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/086", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R1/086", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R2499/11", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R2499/13", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 58052801