PATENT DOCUMENT

Publication Number: US-9185480-B2
Application Number: US-201213716015-A
Country: US
Kind Code: B2

Title: Acoustically actuated mechanical valve for acoustic transducer protection

Abstract:
A portable electronic device including an outer case having a wall in which a transducer-associated acoustic hole is formed. An inner case may be positioned inside the outer case. The inner case can include an acoustic port that opens to the transducer-associated acoustic hole and a relief port that opens to the outer case. A transducer having a diaphragm facing the acoustic port of the inner case is mounted within the inner case. A valve is further positioned over the relief port. The valve is configured to reduce an impact of an incoming air burst on the diaphragm.

Claims:
What is claimed is: 
     
       1. A portable electronic device comprising:
 an outer case having a wall in which a transducer-associated acoustic hole is formed; 
 an inner case positioned inside the outer case, the inner case having an acoustic port that opens to the transducer-associated acoustic hole and a relief port that opens to the outer case; 
 a micro-electro-mechanical systems (MEMS) microphone having a diaphragm facing the acoustic port of the inner case, the microphone being mounted within the inner case; and 
 a valve positioned over the relief port, wherein the valve is operable to open the relief port in response to an incoming air burst through the acoustic port to protect the microphone against the incoming air burst. 
 
     
     
       2. The portable electronic device of  claim 1  wherein the diaphragm divides the inner case into a front chamber acoustically coupled to the acoustic port and a rear chamber, wherein the front chamber is substantially acoustically sealed from the rear chamber. 
     
     
       3. The portable electronic device of  claim 2  wherein the relief port is formed within the rear chamber. 
     
     
       4. The portable electronic device of  claim 2  wherein the relief port is formed within the front chamber. 
     
     
       5. The portable electronic device of  claim 1  wherein the valve is a pressure sensitive valve operable to transition between a closed position and an open position when a pressure changes within the inner case. 
     
     
       6. The portable electronic device of  claim 1  wherein the valve is a piezoelectric valve operable to transition between a closed position and an open position when a pressure on the diaphragm changes. 
     
     
       7. A portable electronic device comprising:
 an outer case having a wall in which a microphone-associated acoustic hole is formed; 
 an inner case located inside the outer case, the inner case having a front chamber and a rear chamber substantially acoustically sealed from the front chamber, wherein the front chamber comprises an acoustic port aligned with the microphone-associated acoustic hole and a relief port; 
 a micro-electro-mechanical systems (MEMS) microphone having a diaphragm facing the acoustic port of the inner case, the microphone being mounted within the rear chamber; and 
 a pressure sensitive valve positioned over the relief port, wherein the pressure sensitive valve transitions between a closed position and an open position in response to an incoming air burst such that in the open position, an impact of the air burst is diverted from the diaphragm to the relief port, and 
 wherein the pressure sensitive valve transitions to the open position in response to a threshold pressure at least two times higher than standard atmospheric pressure. 
 
     
     
       8. The portable electronic device of  claim 7  wherein the acoustic port is formed along a face of the inner case and the relief port is formed along a side wall of the inner case. 
     
     
       9. The portable electronic device of  claim 7  wherein the pressure sensitive valve is integrally formed as part of the microphone. 
     
     
       10. A portable electronic device comprising:
 an outer case having a wall in which a microphone-associated acoustic hole is formed; 
 an inner case located inside the outer case, the inner case having a front chamber and a rear chamber substantially acoustically sealed from the front chamber, wherein the front chamber comprises an acoustic port aligned with the microphone-associated acoustic hole and the rear chamber comprises a relief port; 
 a microphone having a diaphragm facing the acoustic port of the inner case, the microphone being mounted between the front chamber and the rear chamber; and 
 a valve associated with the relief port, wherein the valve is a piezoelectric valve operable to deform to open the relief port when a pressure change on the diaphragm corresponds to a predetermined threshold pressure and modify a pressure within the rear chamber. 
 
     
     
       11. The portable electronic device of  claim 10  wherein the relief port is formed within a wall of the inner case opposite the microphone-associated acoustic hole. 
     
     
       12. The portable electronic device of  claim 10  wherein the relief port is formed within a side wall of the inner case.

Description:
FIELD 
     An embodiment of the invention is directed to an acoustic transducer having a valve to protect against acoustic shock, more specifically a microphone with a mechanical valve to protect against a sudden air burst. Other embodiments are also described and claimed. 
     BACKGROUND 
     Cellular telephone handsets and smart phone handsets have within them a microphone that converts input sound pressure waves produced by the user speaking into the handset, into an output electrical audio signal. The handset typically has a housing with an opening through which incoming sound pressure waves created by the user&#39;s voice can reach the microphone. This opening, however, can also allow for entry of rapid air bursts when, for example, the phone unintentionally and forcefully collides with a flat surface or a user tries to clean the device with a high pressure air flow. If these rapid air bursts reach the microphone, the transducer experiences a sudden acoustic shock that, in some cases, can damage a flexible diaphragm and/or a rigid back plate, found within certain microphones, which are not designed to withstand such a force. 
     SUMMARY 
     An embodiment of the invention is a portable electronic device having an outer case with at least one wall in which a transducer-associated acoustic port (the transducer to be installed inside the outer case) is formed. In some embodiments, the transducer may be a microphone, such as a micro-electro-mechanical systems (MEMS) microphone. The MEMS microphone may include various components, for example a pressure sensitive diaphragm, which are sensitive to a sudden acoustic shock, such as one that may be directed into the case through the acoustic port when the device experiences a sudden, forceful collision with a flat surface on the side having the acoustic port. In this aspect, the invention further includes a valve positioned over a relief port formed within an inner case containing the transducer. The valve may be configured to reduce an impact of the incoming air burst on the diaphragm of the transducer. In some embodiments, the valve may be a pressure sensitive valve capable of transitioning between a closed position and an open position in response to a pressure change within the inner case. In other embodiments, the valve may be a piezoelectric valve capable of transitioning between a closed position and an open position in response to a pressure change on the diaphragm. In still further embodiments, the valve may be a magnetic valve capable of transitioning between a closed position and an open position in response to a momentum force, which occurs when the device is dropped and/or collides with a hard surface. 
     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 
       The embodiments are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and they mean at least one. 
         FIG. 1  illustrates a cross-sectional side view of one embodiment of a transducer having a valve to protect against a sudden air burst. 
         FIG. 2  illustrates a cross-sectional side view of another embodiment of a transducer having a valve to protect against a sudden air burst. 
         FIG. 3  illustrates a cross-sectional side view of another embodiment of a transducer having a valve to protect against a sudden air burst. 
         FIG. 4A  illustrates a cross-sectional side view of another embodiment of a transducer having a valve to protect against a sudden air burst in a closed position. 
         FIG. 4B  illustrates a cross-sectional side view of the valve of  FIG. 4A  in an open position. 
         FIG. 5A  illustrates a cross-sectional side view of another embodiment of a transducer having a valve to protect against a sudden air burst in a closed position. 
         FIG. 5B  illustrates a cross-sectional side view of the valve of  FIG. 5A  in an open position. 
         FIG. 6A  illustrates a front perspective view of one embodiment of a portable electronic device within which a valve for transducer protection can be implemented. 
         FIG. 6B  illustrates a back perspective view of the portable electronic device of  FIG. 6A . 
         FIG. 7  illustrates a schematic diagram of one embodiment of a portable electronic device. 
         FIG. 8  illustrates a schematic diagram of one embodiment of a portable electronic device. 
     
    
    
     DETAILED DESCRIPTION 
     In this section we shall explain several preferred embodiments of this invention with reference to the appended drawings. Whenever the shapes, relative positions and other aspects of the parts described in the embodiments are not clearly defined, the scope of the invention is not limited only to the parts shown, which are meant merely for the purpose of illustration. Also, while numerous details are set forth, it is understood that some embodiments of the invention may be practiced without these details. In other instances, well-known structures and techniques have not been shown in detail so as not to obscure the understanding of this description. 
       FIG. 1  illustrates a cross-sectional side view of one embodiment of a valve for protecting a transducer within an electronic device. Outer housing or case  102  may define or close off a chamber in which the constituent electronic components of electronic device  100 , for example a mobile communications device, are contained. Outer case  102  may therefore include a face  104  (e.g., a front face), a face  106  (e.g., a back face) and side walls  108 ,  110  connecting face  104  to face  106 . An acoustic hole  112  may be formed within any one or more of face  104 , face  106  or side walls  108 ,  110  and may be dimensioned to provide an acoustic input or output to or from electronic device  100 . In this case, acoustic hole  112  may be a transducer-associated acoustic hole which is acoustically coupled to transducer  114  contained within outer case  102 . 
     In one embodiment, transducer  114  may be a microphone, such as a MEMS microphone, a condenser microphone or any other variant of a condenser microphone, which is contained within an inner case  116  mounted within outer case  102 . Inner case  116  may include an acoustic port  118  aligned with acoustic hole  112  such that, in the case of a microphone, a sound external to outer case  102  (e.g., a user&#39;s voice) can travel through outer case  102  and inner case  116  to transducer  114 . Transducer  114  may include a pressure-sensitive diaphragm  120  which vibrates in response to the externally generated sound waves. These vibrations are then converted into electrical current by transducer  114 , which in turn become the audio signal (e.g., audio signal within a frequency range of from about 20 Hz to about 20 kHz) that can be transmitted to, for example, a far end user in the case of a communications device or audio/video recording device. In this aspect, transducer  114  may include or be associated with processing components such as circuitry (which has been omitted for clarity) and may be electrically connected to printed circuit board  134  by, for example wiring or surface mount technology  160 , to facilitate its operation. 
     In some embodiments, diaphragm  120  may divide inner case  116  into a front chamber  122  which is acoustically coupled to one face of diaphragm  120  and a rear chamber  124  which is acoustically coupled to the other face of diaphragm  120 . Rear chamber  124  may be substantially acoustically sealed from front chamber  122  and define a substantially confined volume of air. As a result, a pressure increase on diaphragm  120  may, in some cases, increase a pressure within rear chamber  124  and thereby create a more compressed volume of air behind diaphragm  120 . When this pressure increase is due to a sudden acoustic shock, for example, an impulsive air burst, diaphragm  120  may be damaged. Such damage may occur, for example, as a result of the air pressure or force on diaphragm  120  and/or because the diaphragm  120  cannot flex due to the compressed air volume behind it to facilitate its response. Such an air burst may occur when, for example, device  100  collides forcefully with a substantially flat surface or a user tries to clean the device with a compressed air duster. A pressure from such an air burst is particularly problematic with respect to transducers associated with ports on the substantially planar faces (e.g., face  104  and face  106 ) of device  100 . For example, when device  100  experiences a collision with a flat surface on face  104  or face  106 , the air pressure builds up as the device meets the surface with which it is colliding and cannot easily escape around the sides of device  100 . Some of the air is therefore forced into the ports, such as acoustic hole  112 , depending upon which side of device  100  impacts the surface. This rapid burst of air can, in turn, rapidly increase a pressure and/or air flow on the associated diaphragm (and in some cases a sealed volume of air behind the diaphragm) and damage the diaphragm, and/or other components within the transducer, particularly MEMS microphone components. It is noted that the terms “air burst,” “rapid air burst” and “impulsive air burst” may be used interchangeably herein and should be understood as referring to a type of sudden acoustic shock caused by a burst of air which occurs suddenly and has a particle velocity sufficient to damage an unprotected transducer diaphragm. Thus, an “air burst” should be understood as having both a pressure and a particle velocity higher than, for example, that which would be produced by a user speaking into the device. 
     In order to protect the transducer  114  (e.g., MEMS microphone), particularly diaphragm  120 , from such air bursts, valve  126  can be co-located near the diaphragm  120  so that the burst of high pressure air follows the path of least resistance, i.e., through the opened valve  126  thus reducing a pressure on diaphragm  120  and/or within inner case  116 . In one embodiment, valve  126  is a mechanical valve positioned over a relief port  128  formed through a wall of inner case  116 . In the illustrated embodiment, relief port  128  is formed within a side wall  136  of inner case  116  which forms part of front chamber  122 . It is contemplated, however, that relief port  128  may be formed within any of the walls of inner case  116  defining front chamber  122 . Still further, in embodiments where transducer  114  is a MEMS microphone, valve  126  may be integrally formed as part of the MEMS device. Valve  126  may be configured to open and/or close in response to a rapid air burst so as to reduce an impact of the air burst on diaphragm  120 . For example, in a resting position, valve  126  is closed such that valve  126  forms a substantially air tight seal over relief port  128 . In response to an air burst through acoustic opening  112 , and in turn a pressure increase within inner case  116  or on diaphragm  120 , valve  126  opens (as illustrated in dashed lines) so that the air can escape out relief port  128 , and in turn the pressure within inner case  116  and on diaphragm  120  decreases. 
     In one embodiment, the change (i.e., increase) in pressure and/or air flow pushes valve  126  open. Valve  126  may therefore be any type of pressure sensitive valve capable of remaining closed during normal atmospheric pressure conditions (e.g., pressure levels caused by a user&#39;s voice) and opening in response to higher atmospheric pressure bursts (e.g., pressure levels sufficient to cause damage to diaphragm  120 ). Representatively, in one embodiment, valve  126  may include a movable member  130  and connecting member  132  that movably connects movable member  130  to inner case  116 . For example, in one embodiment, movable member  130  is a substantially rigid structure dimensioned to completely cover and form an air tight seal over relief port  128  in the closed position. Representatively, movable member  130  may be a substantially planar, disk or beam shaped structure where relief port  128  is a circular or elongated port, respectively. Connecting member  132  may be a hinge, spring or other similar mechanism that connects to movable member  130  at one end and inner case  116  at another end and allows movable member  130  to transition from the closed position in which relief port  128  is covered to an open configuration in which relief port  128  is uncovered, and vice versa. For example, valve  126  may be a spring beam type mechanism mounted near relief port  128 . In still further embodiments, it is contemplated that movable member  130  may be integrally formed as a part of the wall of inner case  116  such that connecting member  132  is simply an articulated region of the inner case wall which allows the movable member  130  to open and close with respect to relief port  128 . Alternatively, movable member  130  may be formed by a flexible membrane made for example of a flexible polymer or rubber material which will transition between open and closed positions in response to a pressure change. 
     Valve  126  may be biased in a closed position and open in response to a predetermined threshold pressure. Valve  126  may be biased in the closed position by, for example, connecting member  132  or formed within the wall of inner case  116  to have a tension which biases it in the closed position. In one embodiment, the predetermined threshold pressure sufficient to open valve  126  may be a pressure greater than a sound pressure capable of being produced under normal circumstances, such as by a user&#39;s voice, but less than a pressure level that may cause damage to diaphragm  120 . Representatively, the predetermined threshold pressure may be a pressure at least about 1.5 times higher than standard atmospheric pressure, for example, from about 2 to about 4 times higher than standard atmospheric pressure. In this aspect, when a pressure on diaphragm  120  or within inner case  116  is equal or greater than the pressure sufficient to break or otherwise damage diaphragm  120 , valve  126  opens so that the pressure can be relieved using relief port  128 . Once the pressure drops below the predetermined threshold pressure, valve  126  returns to the closed position. 
       FIG. 2  illustrates a cross-sectional side view of another embodiment of a valve for microphone protection. Each of the components of electronic device  200  are substantially the same as those described in reference to device  100  of  FIG. 1 , except in this embodiment, relief port  228  is formed within a portion of inner case  116  forming rear chamber  124 . Representatively, relief port  228  may be formed within side wall  236 , which is opposite side wall  136 . As can be seen from  FIG. 2 , side wall  236  forms a portion of rear chamber  124 . Valve  226  includes movable member  230  connected to side wall  236  by connecting member  232 . Movable member  230  and connecting member  232  may have any of the previously discussed configurations such that valve  226  is biased in a closed position in the resting state. Similar to the valve of  FIG. 1 , valve  226  opens in response to a predetermined threshold value. Since in this embodiment, however, valve  226  covers a relief port  228  within rear chamber  124 , a threshold pressure within rear chamber  124  triggers valve opening and closing. 
     As previously discussed, rear chamber  124  is a substantially sealed chamber, with the exception of, in some cases, a small perforation  202  used for pressure equalization or to act as a high pass filter. As such, when an air burst entering through acoustic port  118  applies a pressure force onto diaphragm  120 , diaphragm  120  is pushed into rear chamber  124  thus reducing the volume of rear chamber  124 , and in turn increasing the pressure within rear chamber  124 . This reduction in volume and increase in pressure makes the air volume within the rear chamber  124  less compliant. Such conditions can damage diaphragm  120  since it is no longer free to move in and out of a compliant volume of air. Valve  226 , however, is responsive to this change in pressure within rear chamber  124  and opens (as illustrated in dashed lines) when the pressure is above a predetermined threshold value, e.g., a pressure greater than a sound pressure capable of being produced under normal circumstances, such as by a user&#39;s voice, but less than a pressure level that may cause damage to diaphragm  120 . When valve  226  opens, air within rear chamber  124  vents out of relief port  228  thus lowering the pressure within rear chamber  124 . Once the pressure is below the predetermined threshold value, valve  226  closes over relief port  228  in a substantially air tight manner so as not to affect an acoustic performance of transducer  114 . 
       FIG. 3  illustrates a cross-sectional side view of another embodiment of a valve for transducer protection. Each of the components of electronic device  300  are substantially the same as those described in reference to device  100  of  FIG. 1  and device  200  of  FIG. 2 , except in this embodiment, relief port  328  is formed within a bottom wall  336  of inner case  116 , which defines a portion of rear chamber  124 . Valve  326  includes a movable member  330  and a connecting member  332  which are substantially similar to the previously discussed movable and connecting members. Since in this embodiment, relief port  328  is formed in a side of inner case  116  facing printed circuit board  134 , an opening or gap  340  may further be provided within printed circuit board  134  so that air can exit inner case  116  through relief port  328 . Similar to valve  226  described in reference to  FIG. 2 , valve  326  is biased in a closed position by connecting member  332  and opens (as illustrated by dashed lines) when a predetermined threshold pressure value within rear chamber  124  is met or exceeded. Valve  326  in turn closes once the pressure is reduced below the threshold value and forms a substantially air tight seal over relief port  328 . 
       FIG. 4A  and  FIG. 4B  illustrate cross-sectional side views of another embodiment of a valve for transducer protection.  FIG. 4A  illustrates electronic device  400  having valve  426  in a closed position and  FIG. 4B  illustrates electronic device  400  having valve  426  in an open position. Similar to the previously discussed electronic devices, electronic device  400  includes an outer case  402  dimensioned to contain the various components of the electronic device  400 , such as transducer  414  and printed circuit board  434 . Outer case  402  may include a face  404  (e.g., a front face), a face  406  (e.g., a back face) and side walls  408  and  410 , which connect face  404  to face  406 . Transducer  414  may be positioned within an inner case  416 , mounted within outer case  402 . In one embodiment, transducer  414  may be a microphone such as a MEMS microphone which is contained within inner case  416 . In this aspect, transducer  414  may include a pressure-sensitive diaphragm  420  which vibrates in response to the externally generated sound waves. These vibrations are then converted into electrical current by transducer  414 , which in turn become the audio signal (e.g., audio signal within a frequency range of from about 20 Hz to about 20 kHz) that can be transmitted to, for example, a far end user in the case of a mobile communications device or to a file such as the case with a video/audio recording. Transducer  414  may include or be associated with processing components such as circuitry (which has been omitted for clarity) and may be electrically connected to printed circuit board  434  to facilitate its operation. Printed circuit board  434 , along with transducer  414 , may be contained within outer case  102 . Inner case  416  may also have faces  436  and  452  which are connected by opposing side walls  450  and  454 . Face  404  of outer case  402  may have an acoustic hole  412  aligned with an acoustic port  418  formed within face  436  of inner case  416 . 
     Transducer  414  may be positioned near acoustic port  418  such that transducer  414  can receive sound from, or emit sound to, the ambient environment outside of device  400  through acoustic hole  412 . Representatively, in one embodiment, diaphragm  420  of transducer  414  faces acoustic port  418  and acoustic hole  412 . Diaphragm  420  may divide inner case  416  into a front chamber  422  which is acoustically coupled to one side of diaphragm  420  and a rear chamber  424 , which is acoustically sealed from front chamber  422  and around a back side of diaphragm  420 . In embodiments where transducer  414  is a microphone, a sound outside of device  400  (e.g., a user&#39;s voice) travels through acoustic hole  412  and acoustic port  418  to transducer  414  where it can be received and converted to an audio signal for transmission to a far end user or other electronic destination. 
     A relief port  428  may further be formed through inner case  416 . Valve  426  is positioned near relief port  428  such that when valve  426  is in a closed position, relief port  428  is covered by valve  426  and when valve  426  is in an open position, relief port  428  is uncovered. In one embodiment, relief port  428  is formed through a portion of inner case  416  defining the rear chamber  424 . In this embodiment, valve  426  operates to reduce a pressure within rear chamber  424  which could cause damage to diaphragm  420 , or other components of transducer  414 . In some embodiments, valve  426  may be a momentum relief mechanism that opens and closes relief port  428  in response to a momentum force on device  400 , which is indicative of a pressure increase within rear chamber  424 . Representatively, when device  400  unintentionally and forcefully collides with a flat surface in a direction  460 , which is the same direction as a gravitational force  462 , a burst of air may enter acoustic port  418  and the pressure of this air burst on diaphragm  420  may be sufficient to push diaphragm  420  into rear chamber  424  thereby increasing a pressure within rear chamber  424  and making the air contained therein less compliant. Valve  426  may therefore be configured to open in response to such a momentum force such that the pressure within rear chamber  424  is prevented from reaching a level sufficient to damage diaphragm  420 . 
     In one embodiment, valve  426  may be a magnetic valve assembly which uses a magnetic force to hold itself in a closed position in a resting state but open in response to a momentum force which is indicative of a damaging pressure increase within rear chamber  424 . In this aspect, valve  426  may include a movable member  430  which is held in place over relief port  428  using retaining members  432 A and  432 B. Movable member  430  may be of any size and dimensions sufficient to entirely cover relief port  428 . Representatively, movable member  430  may be a substantially planar disk shaped structure having substantially the same shape (e.g., circle, oblong or square shape) as relief port  428 . It is contemplated, however, that in other embodiments, movable member  430  may cover less than the entire relief port  428  when in the closed position if desired. Retaining members  432 A and  432 B may have a substantially “L” shaped profile such that one end can be attached to portions of face  452  of inner case  416  which are near relief port  428  and the other end (e.g., ends  456  and  458 ) overlaps the edges of movable member  430 . The overlapping ends  456  and  458  may be spaced a sufficient distance from the surface of face  452  of inner case  416  such that movable member  430  can move between the surface of face  452  and the interfacing surface of ends  456  and  458 . In the closed position, movable member  430  is magnetically attached to the surface of face  452  while in the open position, movable member  430  is separated from face  452  in a direction of retaining members  432 A and  432 B. It is noted that although substantially “L” shaped retaining members  432 A and  432 B are described, any mechanism capable of retaining movable member  430  over relief port  428  and allowing movable member  430  to move in response to a momentum force may be used, e.g., a spring mechanism, a hinge assembly or the like. 
       FIG. 4B  illustrates movable member  430  in the open position in which relief port  428  is open so that a pressure within rear chamber  424  can be relieved. The transition of valve  426  from the closed position of  FIG. 4A  to the open position of  FIG. 4B  will now be described in more detail. Representatively, movable member  430  may have a predetermined magnetic force (F mag ) which attracts movable member  430  to the inner surface of face  452  near relief port  428  and therefore holds movable member  430  in the closed position in a resting state. In this aspect, movable member  430  may be a magnet and inner case  416  may be formed from, or have mounted thereto, a material suitable for attracting a magnet, e.g., steel. When device  400  is abruptly moved in a direction of arrow  460 , which is the same direction as the gravitational pull  462  on device  400 , movable member  430  experiences a momentum force (M g ) in a direction  464 . A burst of air may also be directed toward diaphragm  420 , which causes an external pressure (P ext ) to be applied to diaphragm  420 . This external pressure (P ext ) may be indicative of a particular momentum force (M g ) and vice versa. Thus, in order to open movable member  430  when an external pressure (P ext ) sufficient to damage diaphragm  420  occurs, movable member  430  may be selected to have a magnetic force (F mag ) which is less than or equal to a momentum force (M g ) which corresponds to the threshold external pressure (P ext ) sufficient to damage diaphragm  120 . In other words, valve  426  will open when F mag ≦P ext ˜M g . Thus, when M g  is greater than or equal to F mag , F mag  will be insufficient to hold movable member  430  against inner case  416  and movable member  430  will essentially fall toward ends  456  and  458  of retaining members  432 A and  432 B. This in turn will open relief port  428  as illustrated by  FIG. 4B . Since relief port  428  is open, any pressure increase within rear chamber  424  caused by the associated air burst, particularly when device  400  contacts a hard surface below, can be relieved out relief port  428  before damage to diaphragm  420  occurs. Once the force of gravity due to the momentum change (M g ) is less than the magnetic force (F mag ) (e.g., device  400  is no longer moving), the magnetic force (F mag ) of movable member  430  will pull movable member  430  back against inner case  416  and close and seal relief port  428 . It is noted that although a magnetic momentum relief mechanism is described in connection with valve  426 , it is contemplated that any type of momentum relief mechanism capable of opening and closing valve  426  in response to a sudden acoustic shock may be used, e.g., a resilient or spring type valve which opens and closes in response to a momentum force. 
       FIG. 5A  and  FIG. 5B  illustrate cross-sectional side views of another embodiment of a valve for microphone protection.  FIG. 5A  illustrates the valve in a closed position and  FIG. 5B  illustrates the valve in an open position. Similar to the previously discussed electronic devices, electronic device  500  includes an outer case  502  dimensioned to contain the various components of the electronic device  500 , such as transducer  514 . Outer case  502  may include a face  504  (e.g., a front face), a face  506  (e.g., a back face) and side walls  508  and  510 , which connect face  504  to face  506 . Transducer  514  may be positioned within an inner case  516 , mounted within outer case  502 . In some embodiments, transducer  514  may be a microphone such as a MEMS microphone electrically connected to printed circuit board  534  to facilitate its operation. Representatively, transducer  514  may include a pressure-sensitive diaphragm  520  which vibrates in response to the externally generated sound waves. These vibrations are then converted into electrical current by transducer  514 , which in turn become the audio signal (e.g., audio signal within a frequency range of from about 20 Hz to about 20 kHz) that can be transmitted to, for example, a far end user in the case of a mobile communications device or to a file such as the case with a video/audio recording. In this aspect, transducer  514  may include or be associated with processing components such as circuitry (which has been omitted for clarity) and may be electrically connected to printed circuit board  534  to facilitate its operation. Printed circuit board  534 , along with transducer  514 , may be contained within outer case  502 . Inner case  516  may also have faces  536  and  552  which are connected by opposing side walls  550  and  554 . Face  504  of outer case  502  may have an acoustic hole  512  aligned with an acoustic port  518  formed within face  536  of inner case  516 . 
     Transducer  514  may be positioned near acoustic port  518  such that transducer  514  can receive sound from, or emit sound to, the ambient environment outside of device  500 . Representatively, in one embodiment, diaphragm  520  of transducer  514  faces acoustic port  518  and acoustic hole  512 . Diaphragm  520  may divide inner case  516  into a front chamber  522  which is acoustically coupled to one side of diaphragm  520  and a rear chamber  524 , which is acoustically sealed from front chamber  522  and around a back side of diaphragm  520 . In embodiments where transducer  514  is a microphone, a sound wave outside of device  500  (e.g., a user&#39;s voice) can travel through acoustic hole  512  and acoustic port  518  to transducer  514  where it can be received and converted to an audio signal for transmission to a far end user. 
     A relief port  528  may further be formed through inner case  516 . Valve  526  is positioned near relief port  528  such that when valve  526  is in a closed position relief port  528  is covered by valve  526  and when valve  526  is in an open position, relief port  528  is uncovered. In one embodiment, relief port  528  is formed through a portion of inner case  516  defining the rear chamber  524 . In this embodiment, valve  526  operates to reduce a pressure within rear chamber  524  when a pressure level rises due to an air burst traveling through acoustic port  518 . In some embodiments, valve  526  may be an electrical-mechanical valve that opens and closes relief port  528  in response to a pressure change associated with diaphragm  520 . Representatively, when a burst of air enters acoustic port  518 , such as where device  500  unintentionally and forcefully collides with a flat surface or is cleaned with a high pressure air burst, the air burst applies a pressure on diaphragm  520 , which in some cases, may be sufficient to damage diaphragm  520  as previously discussed. Valve  526  may therefore be configured to open in response to such a pressure on diaphragm  520 , thus preventing any subsequent pressure increase within rear chamber  524  from reaching a level sufficient to damage diaphragm  520 . Representatively, valve  526  may be made of a piezoelectric material that can deform and open relief port  528  in response to a predetermined threshold value corresponding to a pressure level sufficient to damage diaphragm. In this aspect, the piezoelectric material may be supported over relief port  528  using, for example a bracket assembly  562  sufficient to hold the material over relief port  528  while still allowing for deformation of the material. The valve  526  may be electrically coupled to a sensor associated with diaphragm  520  that can sense an acoustic signal produced by transducer  514 , which corresponds to a pressure on diaphragm  520 , or a pressure or force on diaphragm  520  directly. A predetermined threshold value, for example a threshold force value, is programmed into the device. In some cases the threshold value may be an acoustic signal that corresponds to an acoustic pressure greater than a sound pressure capable of being produced under normal circumstances, such as by a user&#39;s voice, but less than a pressure level that may cause damage to diaphragm. When a force or signal greater than or equal to the predetermined threshold value is detected by the sensor, an electrical current is supplied to the piezoelectric material of valve  526  (such as by associated circuitry, which is not shown) causing the material to deform (e.g., contract) such that relief port  528  is opened as illustrated by  FIG. 5B . The pressure within rear chamber  524  can then be relieved through relief port  528 . When the sensor detects that the acoustic signal has fallen below the threshold value, the electrical current is terminated such that the piezoelectric material of valve  526  returns to its resting, undeformed, state thereby closing relief port  528 . 
       FIG. 6A  and  FIG. 6B  illustrate front and back perspective views of a portable electronic device  600 , for example, a mobile communications device (also referred to as a wireless or mobile telephone), within which any of the above described valves may be implemented. Further details of the device  600  are given below in connection with the description of  FIG. 7  and  FIG. 8 . For now, it should be appreciated that device  600  has an outer housing or case  602  defining or closing off a chamber in which the constituent electronic components of the device  600  are housed. Outer case  602  includes a substantially planar front face  604  and a substantially planar back face  606 , which are connected by a sidewall portion  608 . The face  604  may be considered a display side of the device in that it may include a touch screen display  628  that serves as an input and a display output for the device. The touch screen display  628  may be a touch sensor (e.g., those used in a typical touch screen display such as found in an iPhone® device by Apple Inc.). Although the touch screen is illustrated on front face  604 , if desired, it may be mounted on the back face  606  of device  600 , on a side wall  608  of device  600 , on a flip-up portion of device  600  that is attached to a main body portion of device  600  by a hinge (for example), or using any other suitable mounting arrangement. The back face  606  may form a back side of the device, which can be held by the user during operation of device  600 . 
     To further enable its use as a mobile communications device, device  600  may include various acoustic openings or ports at different locations within outer case  602  to allow for transmission of acoustic signals to and from device  600 . Representatively, outer case  602  may have formed therein a speaker acoustic port  610 , a receiver acoustic port  612  and microphone acoustic ports  616 ,  618 ,  620 . Although the acoustic ports are illustrated as separate ports, it is contemplated that any one or more of the illustrated ports may be combined into one port such that, for example, the transducers associated with the illustrated receiver or microphone ports may instead share the same port. In one embodiment, the receiver acoustic port  612  is formed within front face  604  of outer case  602  and speaker acoustic port  610  is formed within an end portion of sidewall  608 . It is contemplated, however, that each of these ports may be formed in other portions of outer case  602 , for example, speaker acoustic port  610  may be on the front face  604  or back face  606  while receiver acoustic port  610  is along the sidewall. Each of these ports may consist of multiple holes clustered together or alternatively a single, large hole as shown. 
     Microphone acoustic ports  616 ,  618  and  620  may be formed along the front face  604 , back face  606  and sidewall  608  of outer case  602  as illustrated. Representatively, in one embodiment, microphone acoustic port  616  is formed in front face  604  while microphone acoustic port  620  is formed in back face  606 . Microphone acoustic port  618  may be formed within a bottom portion of sidewall  608 . Although  FIG. 6A  and  FIG. 6B  illustrate a single microphone acoustic port formed within each of the above described portions of outer case  602 , it is contemplated that more than one microphone acoustic port may be formed in one or more of these portions. For example, two microphone acoustic ports may be formed along front face  604  or back face  606 . 
     Each of the speaker acoustic port  610 , receiver acoustic port  612  and microphone acoustic ports  616 ,  618  and  620  may be associated with one or more of the previously discussed transducers, which are mounted within outer case  602 . In the case of the microphone acoustic ports  616 ,  618  and  620 , the transducer is an acoustic-to-electric transducer such as a microphone that converts sound into an electrical signal. The microphone may be any type of microphone capable of receiving acoustic energy, for example sound through the associated port, and converting it into an electrical signal. For example, in one embodiment, the microphone may be MEMS microphone, also referred to as a microphone chip or silicon microphone. In this aspect, various features of the microphone such as the pressure-sensitive diaphragm and in some cases a protective valve as previously discussed, are etched directly into a silicon chip by MEMS techniques. 
     The MEMS microphone components, including the pressure-sensitive diaphragm, while sensitive to acoustic pressures, may also be sensitive to sudden acoustic shocks such as high pressure, impulsive air bursts as previously discussed. Such an air burst may occur when, for example, device  600  collides forcefully with a substantially flat surface or a user tries to clean the device with a compressed air duster. A pressure from such an air burst is particularly problematic with respect to microphones associated with ports on the substantially planar faces (e.g., front face  604  and back face  606 ) of device  600 . In order to protect the MEMS microphone, particularly the diaphragm, from such air bursts, any of the previously described valves may be co-located near the diaphragm within a shared sealed volume so that the burst of high pressure follows the path of least resistance, i.e., through the opened valve as previously discussed. 
     Cameras  622 ,  624  may further be mounted to outer case  602  to capture still and/or video images of objects of interest. In the illustrated embodiment, cameras  622 ,  624  are mounted along the front face  604  and back face  606  of outer case  602 , respectively. It is contemplated, however, that in some embodiments, cameras  622 ,  624  may be mounted along the same side or face of outer case  602 , or one of cameras  622 ,  624  may be omitted such that a camera is mounted on only one side of outer case  602 . 
     The outer case  602  may further include other input-output devices such as an earphone port (not shown) to receive an earphone plug, docking port  614  and command button  626 . Docking port  614  may sometimes be referred to as a dock connector, 30-pin data port connector, input-output port, or bus connector, and may be used as an input-output port (e.g., when connecting device  600  to a mating dock connected to a computer or other electronic device). Command button  626  may be, for example, a menu button or any other device that can be used to supply an input to and/or operate device  600 . 
       FIG. 7  illustrates a block diagram of one embodiment of an electronic device within which any of the previously discussed valves may be implemented. As shown in  FIG. 7 , device  700  may include storage  702 . Storage  702  may include one or more different types of storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory), volatile memory (e.g., battery-based static or dynamic random-access-memory), etc. 
     Processing circuitry  704  may be used to control the operation of device  700 . Processing circuitry  704  may be based on a processor such as a microprocessor and other suitable integrated circuits. With one suitable arrangement, processing circuitry  704  and storage  702  are used to run software on device  700 , such as internet browsing applications, voice-over-internet-protocol (VOIP) telephone call applications, email applications, media playback applications, operating system functions, etc. Processing circuitry  704  and storage  702  may be used in implementing suitable communications protocols. Communications protocols that may be implemented using processing circuitry  704  and storage  702  include internet protocols, wireless local area network protocols (e.g., IEEE 802.11 protocols—sometimes referred to as Wi-Fi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol, protocols for handling 3G or 4G communications services (e.g., using wide band code division multiple access techniques), 2G cellular telephone communications protocols, etc. 
     To minimize power consumption, processing circuitry  704  may include power management circuitry to implement power management functions. For example, processing circuitry  704  may be used to adjust the gain settings of amplifiers (e.g., radio-frequency power amplifier circuitry) on device  700 . Processing circuitry  704  may also be used to adjust the power supply voltages that are provided to portions of the circuitry on device  700 . For example, higher direct-current (DC) power supply voltages may be supplied to active circuits and lower DC power supply voltages may be supplied to circuits that are less active or that are inactive. If desired, processing circuitry  704  may be used to implement a control scheme in which the power amplifier circuitry is adjusted to accommodate transmission power level requests received from a wireless network. 
     Input-output devices  708  may be used to allow data to be supplied to device  700  and to allow data to be provided from device  700  to external devices. Display screen  628 , button  626 , microphone acoustic ports  616 ,  618  and  620 , speaker acoustic port  610 , and docking port  614  are examples of input-output devices  708 . 
     Input-output devices  708  can also include user input-output devices  706  such as buttons, touch screens, joysticks, click wheels, scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, etc. A user can control the operation of device  700  by supplying commands through user input devices  706 . Display and audio devices  710  may include liquid-crystal display (LCD) screens or other screens, light-emitting diodes (LEDs), and other components that present visual information and status data. Display and audio devices  710  may also include audio equipment such as speakers and other devices for creating sound. Display and audio devices  710  may contain audio-video interface equipment such as jacks and other connectors for external headphones and monitors. 
     Wireless communications devices  712  may include communications circuitry such as radio-frequency (RF) transceiver circuitry formed from one or more integrated circuits, power amplifier circuitry, passive RF components, antennas, and other circuitry for handling RF wireless signals. Wireless signals can also be sent using light (e.g., using infrared communications). Representatively, in the case of microphone acoustic ports  616 ,  618  and  620 , one or more of transducers  114 ,  414  or  514  associated with these ports may be in communication with an RF antenna for transmission of signals from the transducer to a far end user. Such a configuration is illustrated in more detail in  FIG. 8 . 
     For example,  FIG. 8  illustrates an embodiment in which each microphone  616 ,  618 ,  620  may be in communication with an audio processor  804  through paths  802 . Paths  802  may include wired and wireless paths. Signals from microphones  616 ,  618 ,  620  may be transmitted through uplink audio signal path  814  to radio  808 . Radio  808  may transmit the signals via downlink audio signal path  816  to audio processor  806 , which is in communication with a far end user device  812  through path  820 . Alternatively, radio  808  may transmit the signals to RF antenna  810  through path  818 . Audio processor  804  may also be in communication with local storage  822 , a media player/recorder application  824  or other telephony applications  826  on the device, through path  832 , for local storage and/or recording of the audio signals as desired. Processor  828  may further be in communication with these local devices via path  834  and also display  830  via path  838  to facilitate processing and display of information corresponding to the audio signals to the user. Display  830  may also be in direction communication with local storage  822  and applications  824 ,  826  via path  836  as illustrated. 
     Returning to  FIG. 7 , device  700  can communicate with external devices such as accessories  714 , computing equipment  716 , and wireless network  718  as shown by paths  720  and  722 . Paths  720  may include wired and wireless paths. Path  722  may be a wireless path. Accessories  714  may include headphones (e.g., a wireless cellular headset or audio headphones) and audio-video equipment (e.g., wireless speakers, a game controller, or other equipment that receives and plays audio and video content), a peripheral such as a wireless printer or camera, etc. 
     Computing equipment  716  may be any suitable computer. With one suitable arrangement, computing equipment  716  is a computer that has an associated wireless access point (router) or an internal or external wireless card that establishes a wireless connection with device  700 . The computer may be a server (e.g., an internet server), a local area network computer with or without internet access, a user&#39;s own personal computer, a peer device (e.g., another portable electronic device  700 ), or any other suitable computing equipment. 
     Wireless network  718  may include any suitable network equipment, such as cellular telephone base stations, cellular towers, wireless data networks, computers associated with wireless networks, etc. For example, wireless network  718  may include network management equipment that monitors the wireless signal strength of the wireless handsets (cellular telephones, handheld computing devices, etc.) that are in communication with network  718 . 
     While certain embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that the invention is not limited to the specific constructions and arrangements shown and described, since various other modifications may occur to those of ordinary skill in the art. For example, any type of valve capable of reducing an impact of an incoming air burst on a transducer may be used, such as a one-way valve system which allows air to exit the relief port to the outer case but does not allow air entry. Still further, although a portable electronic device such as a mobile communications device is described herein, any of the previously discussed valve and transducer configurations may be implemented within a tablet computer, personal computer, laptop computer, notebook computer and the like. The description is thus to be regarded as illustrative instead of limiting.

Metadata:
Filing Date: 20121214
Publication Date: 20151110
Grant Date: 20151110
Priority Date: 20121214
Inventors: HOWES MICHAEL B.
STIEHL KURT R.
Assignee: APPLE INC
CPC Classifications: [{"code": "H04R2420/07", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/086", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R2420/07", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/086", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 50930912