PATENT DOCUMENT

Publication Number: US-10209123-B2
Application Number: US-201615245856-A
Country: US
Kind Code: B2

Title: Liquid detection for an acoustic module

Abstract:
An acoustic module is coupled to an acoustic passage. The acoustic module includes an acoustic transducer coupled to a diaphragm. A controller or other circuitry measures an impedance of the acoustic transducer. Based on the impedance, the controller determines whether the impedance indicates that the acoustic passage is blocked. The controller may determine that the acoustic passage is blocked by liquid that is present in the acoustic passage. When the controller determines based on the impedance that liquid is present in the acoustic passage, the controller may drive out, purge, and/or otherwise remove the liquid, such as by using the acoustic transducer to vibrate the diaphragm.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a housing; 
 an acoustic passage internal to the housing; 
 an acoustic transducer coupled to the acoustic passage; and 
 circuitry electrically coupled to the acoustic transducer and operable to:
 measure an impedance of the acoustic transducer at approximately a reference frequency of the acoustic transducer; and 
 detect a presence of liquid based on the measured impedance; wherein: 
 
 the reference frequency corresponds to a resonant frequency of the acoustic transducer in an unobstructed condition; and 
 the presence of liquid is detected based on a reduction of impedance over a range of frequencies that includes the resonant frequency as compared to a reference value. 
 
     
     
       2. The electronic device of  claim 1 , wherein
 the reference value corresponds to an operation of the acoustic transducer without the presence of liquid. 
 
     
     
       3. The electronic device of  claim 2 , wherein:
 the presence of liquid is detected when the measured impedance is approximately equal to the impedance of the acoustic transducer when dry at a non-resonant frequency. 
 
     
     
       4. An electronic device, comprising:
 a housing; 
 an acoustic passage internal to the housing; 
 an acoustic transducer coupled to the acoustic passage; and 
 circuitry electrically coupled to the acoustic transducer and operable to:
 measure an impedance of the acoustic transducer at approximately a reference frequency of the acoustic transducer; 
 detect a presence of liquid based on the measured impedance; and 
 apply a drive signal to a transducer, the drive signal is configured to purge the liquid from the acoustic passage. 
 
 
     
     
       5. The electronic device of  claim 4 , wherein:
 the transducer is the acoustic transducer; and 
 the drive signal is a voltage signal. 
 
     
     
       6. The electronic device of  claim 4 , wherein the transducer is separate from the acoustic transducer. 
     
     
       7. The electronic device of  claim 4 , wherein the circuitry is further operable to:
 measure an updated impedance of the acoustic transducer while applying the drive signal; and 
 adjust the drive signal based on the updated impedance. 
 
     
     
       8. An electronic device, comprising:
 a housing; 
 a port defined in the housing; 
 an acoustic module coupled to the port, the acoustic module including an acoustic transducer; and 
 a controller coupled to the acoustic module and operable to:
 measure an impedance of the acoustic transducer at approximately a resonant frequency of the acoustic transducer; 
 determine a blockage condition based on the measured impedance; and 
 distinguish if the blockage condition is due to a blockage of the port or a foreign material within the housing. 
 
 
     
     
       9. The electronic device of  claim 8 , wherein the controller is further configured to estimate a type of foreign material within the housing based on the measured impedance. 
     
     
       10. The electronic device of  claim 8 , wherein the controller measures the impedance prior to signaling the acoustic module to provide output. 
     
     
       11. The electronic device of  claim 8 , wherein the acoustic module comprises at least one of a speaker or a microphone. 
     
     
       12. An electronic device, comprising:
 a housing; 
 a port defined in the housing; 
 an acoustic module coupled to the port, the acoustic module including an acoustic transducer; 
 a microphone; and 
 a controller coupled to the acoustic module and the microphone, the controller operable to:
 measure an impedance of the acoustic transducer at approximately a resonant frequency of the acoustic transducer; 
 determine a blockage condition based on the measured impedance; 
 measure an ambient acoustic level; and 
 in response to the measured ambient acoustic level exceeding a threshold, drive the acoustic transducer at the resonant frequency and measure the impedance of the acoustic transducer. 
 
 
     
     
       13. The electronic device of  claim 12 , wherein the controller:
 determines the blockage condition is a presence of liquid in the port; and 
 drives the liquid out of the port. 
 
     
     
       14. The electronic device of  claim 13 , wherein the controller ceases driving the liquid out of the port in response to an updated impedance. 
     
     
       15. The electronic device of  claim 14 , wherein the updated impedance indicates the liquid is not present in the port. 
     
     
       16. An electronic device, comprising:
 an enclosure; 
 an acoustic module including an acoustic transducer, the acoustic module coupled to a passage within an interior of the enclosure; 
 a detector coupled to the acoustic transducer operable to measure a change in impedance of the acoustic transducer; and 
 a processing unit coupled to the detector operable to determine a blockage condition based on the change in impedance; wherein the processing unit uses the impedance to determine at least one of an amount of a contaminant or a type of a contaminant. 
 
     
     
       17. The electronic device of  claim 16 , wherein the detector comprises a sensing resistor. 
     
     
       18. The electronic device of  claim 16 , further comprising a capacitive touch component coupled to the processing unit, wherein the detector measures the impedance in response to a signal from the capacitive touch component. 
     
     
       19. The electronic device of  claim 16 , wherein the processing unit is operable to respond to a query regarding whether the electronic device has been exposed to contaminants. 
     
     
       20. The electronic device of  claim 16 , wherein the processing unit is operable to prompt a user before attempting to remove contaminants from the passage.

Description:
FIELD 
     The described embodiments relate generally to acoustic modules, such as speakers and microphones. More particularly, the present embodiments relate to detection of liquid in an acoustic module by measuring a change in impedance or response of an acoustic transducer. 
     BACKGROUND 
     Many electronic devices include acoustic devices (such as microphones or speakers) in order to record sound, output sound, and/or perform other functions. In order to transmit sound, an acoustic device may be coupled to an external environment through an acoustic path. However, the acoustic path may expose the acoustic device to liquids or other contaminants from the external environment. The presence of liquid or other contaminants on or around the acoustic device may adversely affect the performance of the device. The present disclosure is directed to systems and techniques for detecting and/or removing a liquid or other contaminant from an acoustic device. 
     SUMMARY 
     The present disclosure relates to detection of liquid in an acoustic module using impedance. Blockages in an acoustic passage faced by an acoustic module alter the impedance of an acoustic transducer coupled to a diaphragm of the acoustic module. The acoustic module and/or an associated electronic device measures the impedance to determine whether or not a blockage is present. In various implementations, the liquid may also be removed, such as by producing tones, noise, or other sound waves to drive out the liquid. 
     In some embodiments, an electronic device includes a housing, an acoustic passage internal to the housing, an acoustic transducer coupled to the acoustic passage, and circuitry electrically coupled to the acoustic transducer. The circuitry is operable to measure an impedance of the acoustic transducer at approximately a reference frequency of the acoustic transducer and detect a presence of liquid based on the measured impedance. 
     In various examples, the reference frequency corresponds to a resonant frequency of the acoustic transducer in an unobstructed condition. In some implementations, the presence of liquid is detected based on a reduction of impedance over a range of frequencies that includes the resonant frequency as compared to a reference value and the reference value corresponds to an operation of the acoustic transducer without the presence of liquid. In various implementations, the presence of liquid is detected when the measured impedance is approximately equal to the impedance of the acoustic transducer when dry at a non-resonant frequency. 
     In numerous examples, the circuitry is further operable to apply a drive signal to a transducer, the drive signal is configured to purge the liquid from the acoustic passage. In various implementations, the transducer is the acoustic transducer and the drive signal is a voltage signal. In some implementations, the transducer is separate from the acoustic transducer. In numerous examples, the circuitry is further operable to measure an updated impedance of the acoustic transducer while applying the drive signal and adjust the drive signal based on the updated impedance. 
     In various embodiments, an electronic device includes a housing; a port defined in the housing; an acoustic module coupled to the port, the acoustic module including an acoustic transducer; and a controller coupled to the acoustic module. The controller is operable to measure an impedance of the acoustic transducer at approximately a resonant frequency of the acoustic transducer and determine a blockage condition based on the measured impedance. 
     In some examples, the controller is further operable to distinguish if the blockage condition is due to a blockage of the port or a foreign material within the housing. In various implementations, the controller is further configured to estimate a type of foreign material within the housing based on the measured impedance. 
     In various examples, the controller measures the impedance prior to signaling the acoustic module to provide output. In some examples, the acoustic module comprises at least one of a speaker or a microphone. 
     In numerous examples, the electronic device further comprises a microphone coupled to the controller. In some implementations of such examples, the controller is further configured to measure an ambient acoustic level and, in response to the measured ambient acoustic level exceeding a threshold, drive the acoustic transducer at the resonant frequency and measure the impedance of the acoustic transducer. 
     In numerous embodiments, an electronic device includes an enclosure; an acoustic module including an acoustic transducer, the acoustic module coupled to a passage within an interior of the enclosure; a detector coupled to the acoustic transducer operable to measure a change in impedance of the acoustic transducer; and a processing unit coupled to the detector. The processing unit is operable to determine a blockage condition based on the change in impedance. 
     In some examples, the detector comprises a sensing resistor. In various examples, the processing unit uses the impedance to determine at least one of an amount of a contaminant or a type of a contaminant. In numerous examples, the electronic device further includes a capacitive touch component coupled to the processing unit and the detector measures the impedance in response to a signal from the capacitive touch component. In various examples, the processing unit is operable to respond to a query regarding whether the electronic device has been exposed to contaminants. In some examples, the processing unit is operable to prompt a user before attempting to remove contaminants from the passage. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements. 
         FIG. 1  depicts an electronic device having an acoustic module. 
         FIG. 2A  depicts a cross-sectional view of an example of the electronic device of  FIG. 1 , taken along line A-A of  FIG. 1 . 
         FIG. 2B  depicts the electronic device of  FIG. 2A  with liquid present in the acoustic passage. 
         FIG. 2C  depicts the electronic device of  FIG. 2A  with an object covering the acoustic opening. 
         FIG. 3A  depicts an example impedance curve of the acoustic transducer of  FIG. 2A . 
         FIG. 3B  depicts another example impedance curve of the acoustic transducer of  FIG. 2B . 
         FIG. 3C  depicts another example impedance curve of the acoustic transducer of  FIG. 2C . 
         FIG. 4  is a simplified schematic embodiment of an acoustic module having a liquid detection module. 
         FIG. 5  depicts a flow chart illustrating a first example method for detecting liquid in an acoustic module using impedance and removing the liquid. The method may be performed by the electronic devices of  FIGS. 1, 2A-2C , and/or  4 . 
         FIG. 6  depicts a flow chart illustrating a second example method for detecting liquid in an acoustic module using impedance and removing the liquid. The method may be performed by the electronic devices of  FIGS. 1, 2A-2C , and/or  4 . 
         FIG. 7  depicts a flow chart illustrating a third example method for detecting liquid in an acoustic module using impedance and removing the liquid. The method may be performed by the electronic devices of  FIGS. 1, 2A-2C , and/or  4 . 
         FIG. 8  depicts a flow chart illustrating an example method for detecting a blockage in an acoustic module using impedance and removing the blockage. The method may be performed by the electronic devices of  FIGS. 1, 2A-2C , and/or  4 . 
         FIG. 9  depicts an alternative example of the electronic device of  FIG. 2A . 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to representative embodiments illustrated in the accompanying drawings. It should be understood that the following descriptions are not intended to limit the embodiments to one preferred embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the described embodiments as defined by the appended claims. 
     The description that follows includes sample systems, methods, and apparatuses that embody various elements of the present disclosure. However, it should be understood that the described disclosure may be practiced in a variety of forms in addition to those described herein. 
     The following disclosure relates to detection of liquid in an acoustic module. For purposes of the following disclosure, an acoustic module may refer to a speaker, microphone, or other device configured to transmit or receive acoustic energy. The presence of liquid may be detected by measuring a change in impedance or an impedance profile over a range of frequencies. In some cases, the acoustic module includes an acoustic transducer or voice coil that is coupled to a diaphragm. The diaphragm may be coupled or otherwise in communication with an acoustic passage through which sound waves produced or received by the diaphragm travel. Blockages in the acoustic passage (such as liquid in the passage contacting the diaphragm, a finger covering an acoustic opening connecting the acoustic passage to an external environment, and so on) may alter the impedance of the acoustic transducer. By measuring and evaluating the impedance and/or a change in impedance, the presence of a blockage or ingress of a liquid or other contaminant may be detected. 
     In some embodiments, a determination may be made as to the type of obstruction that may be present. For example, by analyzing the impedance or change in impedance, a determination may be made as to whether the acoustic device is blocked or that a liquid or other contaminant is present within or on a diaphragm of the acoustic module. By way of example, by analyzing the impedance, the acoustic module and/or the associated electronic device may determine whether the obstruction is due to liquid, dirt, and/or other contaminants present in the acoustic passage, whether the acoustic opening connecting the acoustic passage and an external environment is covered, the amount and/or type of contaminant present in the acoustic passage, and so on. 
     In some implementations, in response to detecting a blockage of a particular type, the acoustic module and/or the associated electronic device may drive out, purge, and/or otherwise remove the blockage. For example, when the blockage is a liquid present in the acoustic passage, the diaphragm may be driven with a specially configured tone or response to drive the liquid out of the device. In some cases, a separate transducer is used to alleviate the blockage. 
     In various implementations, the acoustic module and/or an associated electronic device may minimize a user perceptibility of the blockage detection and/or removal. For example, where detection and/or removal produces sound, the detection and/or removal may be delayed until an ambient or other sound level is above a threshold so that the produced sound is less perceptible. In some cases, the detection and/or removal may be delayed until the user responds to a prompt or other cue to avoid an undesired or unexpected acoustic output. 
     The impedance of the acoustic transducer may be monitored in different manners in different implementations. The impedance may be monitored continuously, periodically, upon the occurrence of a triggering event, and so on. For example, in various implementations, the impedance may be measured once per hour, at a user specified interval, prior to using the acoustic module to provide output, upon receiving a signal from another sensor or device, and so on. 
     These and other embodiments are discussed below with reference to  FIGS. 1-9 . However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these Figures is for explanatory purposes only and should not be construed as limiting. 
       FIG. 1  depicts an electronic device  100  having an acoustic module. In accordance with some embodiments, the electronic device  100  is configured to detect liquid or other foreign material or contaminant in an acoustic module using a measured impedance or change in impedance. In this example, the electronic device  100  is depicted as a smart phone having a touch sensor  101  or touch screen that is configured to receive touch input from a user. The electronic device  100  also includes a housing  102  or other enclosure that defines an exterior surface of the electronic device  100  and an internal volume that houses the internal components of the electronic device  100 . In this example, the housing  102  includes multiple openings for various acoustic devices. Specifically, the housing  102  defines an acoustic opening  103  for a microphone or other acoustic device and a set of acoustic openings  104  for a speaker or other acoustic device. 
     While the present example is provided with respect to a smart phone, the embodiments described herein may also be applied to a variety of electronic devices including, for example, a wearable electronic device, a notebook computing device, a tablet computing device, a portable media player, a health monitoring device, and other portable electronic devices that include a speaker or other acoustic module. The embodiments described herein may also be applied to a desktop computing device, an electronic appliance, display device, external microphone or speaker, printer, keyboard device, or other electronic device having an acoustic module. 
     The electronic device  100  is operable to determine whether or not liquid (or other foreign contaminant) is present in an acoustic passage or port connected to the set of acoustic openings  104  based on a measured impedance or change in impedance of the acoustic transducer. If liquid is detected, the electronic device  100  may perform one or more actions to drive out, purge, and/or otherwise remove the liquid from the acoustic passage. The electronic device  100  may also be configured to distinguish between a blockage of one of the acoustic openings  103 ,  104  and a foreign contaminant present within the housing  102  of the electronic device  100 . 
       FIG. 2A  depicts a cross-sectional view of an example of the electronic device  100  of  FIG. 1 , taken along line A-A of  FIG. 1 . The example acoustic module  205  may be coupled to control circuitry  213  that is configured to detect a blockage based on an impedance measurement. In some embodiments, the control circuitry  213  is configured to measure the impedance or a change in impedance at or around a reference frequency of the acoustic module  205 . The reference frequency may correspond to the resonance frequency of the acoustic module  205  when dry or un-obstructed. 
     As shown in  FIG. 2A , the acoustic module  205  is disposed within an internal volume or interior defined within the housing  102 . A structure  207  (or housing, enclosure, and so on) may include a wall or other structural element that is coupled to the housing  102  and defines the acoustic passage  206  or channel between the acoustic module  205  and one or more of the set of acoustic openings  104 . The acoustic passage  206  allows acoustic energy (e.g., sound waves, acoustic signals) to be transmitted between the acoustic module  205  and the external environment via the acoustic opening  104 . 
     As shown in  FIG. 2A , the acoustic module  205  includes an acoustic transducer having a diaphragm  209  coupled to an enclosure  208  and a voice coil  210  coupled to the diaphragm  209 . A center magnet  211  and a side magnet  212  may also be coupled to the enclosure  208 . If operating as a speaker, the voice coil  210  is configured to electromagnetically couple to the magnets  211 ,  212  and displace the diaphragm  209  to produce an acoustic signal. If operating as a microphone, acoustic energy may cause the diaphragm  209  to displace, which causes a movement of the voice coil  210  with respect to the magnets  211 ,  212  and results in an electrical signal (e.g., a current signal) being generated by the voice coil  210 . 
     In the example of  FIG. 2A , the device includes control circuitry  213  that is operatively coupled to the acoustic module  205 . In some instances, the control circuitry  213  includes a processing unit, controller, or other control circuitry that is configured to control or interface with the acoustic module  205 . The control circuitry  213  may also include a driver and/or sensing circuitry that is configured to send and/or receive electrical signals to or from the voice coil  210  via an electrical connection  214 . If operating as a speaker, the control circuitry  213  may be configured to deliver a current signal to drive the voice coil  210  and produce an acoustic signal. In some cases, the voice coil  210  generates a magnetic flux when an alternating current passes through the voice coil  210 . This magnetic flux interacts with magnetic fields of the center magnet  211  and side magnets  212  to vibrate and/or otherwise displace the diaphragm  209  and produce sound waves or other acoustic energy. 
     In this example, the acoustic module  205  is a speaker. However, it is understood that this is an example. In various implementations, the acoustic module  205  may be any kind of acoustic device, such as a microphone, that includes a voice coil  210  and a diaphragm  209 . If operating as a microphone, the control circuitry  213  may be configured to detect a current signal produced by the voice coil  210 , which may correspond to an acoustic signal received by the acoustic module  205 . 
     Optimal operation of the acoustic module  205  may depend on free movement of the diaphragm  209  and the ability of sound waves or acoustic energy to travel through the acoustic passage  206  unimpeded. In the example of a speaker, sound waves generated by movement of the diaphragm  209  may travel through the acoustic passage  206  out one or more of the set of acoustic openings  104 . In the example of a microphone, sound waves may travel in one or more of the set of acoustic openings  104 , travel through the acoustic passage  206 , and vibrate or otherwise move the diaphragm  209 , generating current through the voice coil  210 . Regardless, a partial or full blockage of the passage may inhibit sound waves from travelling (and/or impair the travel of the sound waves) through the acoustic passage  206  and/or one or more of the set of acoustic openings  104 . A partial and/or full blockage may also restrict or impair motion of the diaphragm  209 , which may alter or impair performance of the acoustic module  205 . 
       FIG. 2B  depicts an example of an acoustic module  205  having a first type of blockage. In particular, the acoustic module  205  includes a foreign object  250  (e.g., a liquid) present in the acoustic passage  206 . This type of blockage may have two primary effects: the liquid may restrict motion of the diaphragm  209  and/or may impair movement of sound waves through the acoustic passage  206 . This may distort or reduce sound produced by the acoustic module  205 , prevent the acoustic module  205  from generating sound, distort or reduce sound detected by the acoustic module  205 , prevent the acoustic module  205  from detecting sound, and so on. 
       FIG. 2C  depicts another example of an acoustic module  205  having a second type of blockage. In particular, the acoustic module  205  includes an object  251  (e.g., a finger) blocking one or more of the set of acoustic openings  104 . This type of blockage may impair movement of sound waves through the acoustic passage  206  and/or may dampen the sound that is produced or received by the acoustic module  205 . 
     In some cases, blocking the one or more of the set of acoustic openings  104  may also restrict motion of the diaphragm  209  due to air pressure in the acoustic passage  206 . However, as the object  251  does not directly contact the diaphragm  209 , any restriction to the movement of the diaphragm  209  motion would be different than the blockage due to the foreign object  250  illustrated in  FIG. 2B . 
     With regard to the example embodiments of  FIGS. 2B-2C , a partial or full blockage of the acoustic passage  206  may alter or affect the impedance of the voice coil  210  as compared to normal or dry operating conditions depicted in  FIG. 2A . As described in more detail below, by analyzing the impedance of the voice coil  210 , the control circuitry  213  may determine whether a blockage is present and/or the type of blockage that has likely occurred. This information may be used to initiate an evacuation measure or procedure. 
       FIGS. 3A-3C  depict example impedances of a voice coil subjected to different conditions. In particular,  FIG. 3A  depicts impedance as a function of frequency over a predetermined frequency range for a dry or normally operating acoustic module.  FIG. 3B  depicts impedance as a function of frequency over a range for an acoustic module having a first type of blockage, which may correspond to a foreign object (e.g., a liquid) being present on a diaphragm or membrane of the acoustic module.  FIG. 3C  depicts impedance as a function of frequency over a range for an acoustic module having a second type of blockage, which may correspond to an object (e.g., a finger) blocking one or more openings in the housing of the device. By analyzing the impedance over a predetermined range, the device may be configured to distinguish between the operating conditions associated with  FIGS. 3A, 3B, and 3C . 
       FIG. 3A  depicts the impedance curve  320 A of an example acoustic transducer operating in dry or normal, unobstructed conditions. With reference to  FIG. 2A , the acoustic transducer may include a voice coil  210 , which may exhibit an impedance response in accordance with the impedance curve  320 A of  FIG. 3A  when operating in an unobstructed state. 
     The highest point of the impedance curve  320 A may correspond to the resonant frequency  321  of the acoustic module  205  in a dry or unobstructed condition. The impedance curve  320 A may exhibit a peak or local maxima at the resonant frequency  321  because the resonant frequency  321  corresponds to the largest and possibly the most rapid displacement over the normal operating frequency range of the acoustic module  205 . Large and rapid displacement tends to increase back EMF, which may be evidenced by an increase in impedance of the voice coil. In some cases, resonant frequency  321  of the acoustic module  205  under dry or unobstructed conditions may serve as a reference frequency at which an impedance is monitored. Changes in impedance measured at this reference frequency may indicate that a blockage has occurred and/or a type of blockage that is affecting the performance of the acoustic module  205 . 
     In general, a blockage that restricts motion of the diaphragm  209  will reduce the impedance  322  at a respective frequency  323  because the movement of the diaphragm  209  will be restricted or altered (as compared to in an unobstructed condition).  FIGS. 3B and 3C  represent example impedance curves when an acoustic module has been obstructed. 
       FIG. 3B  depicts the impedance curve  320 B that may correspond to a first type of blockage condition in which a foreign object, such as a liquid, is present on or near the diaphragm or voice coil of the acoustic transducer. By way of illustration, this type of blockage may correspond to the example of  FIG. 2B , in which the foreign object  250  (e.g., a liquid) restricts or impedes the motion of the diaphragm  209  and/or the voice coil  210 . In some cases, the presence of the foreign object  250  may increase the amount of mass that is displaced during operation of the acoustic transducer in which the diaphragm  209  moves or vibrates. The additional mass may restrict the motion of the diaphragm  209  and alter the natural or resonant frequency of the acoustic transducer. In some cases, the resonant frequency of the acoustic transducer is shifted outside of the predetermined frequency range represented by the impedance curve  320 B of  FIG. 3B . 
     As shown in  FIG. 3B , this type of blockage may result in an impedance curve  320 B that is substantially flattened due to the presence of the foreign object  250  (e.g., a liquid). As compared to the unobstructed acoustic transducer of  FIG. 3A  having curve  320 A, the impedance curve  320 B of  FIG. 3B  may exhibit no substantial peak or local maxima with regard to measured impedance  322  over the frequency range  323 . Notably, the impedance at the reference frequency  321  (e.g., the unobstructed resonant frequency) may be lower or reduced for the impedance curve  320 B as compared to the impedance curve  320 A. In some cases, the average impedance over the frequency range  323  may be lower or reduced for the impedance curve  320 B as compared to the impedance curve  320 A. The predetermined frequency range may, for example, correspond to the audible frequency range of the human ear. In some cases, the predetermined frequency range is between 20 and 20,000 Hz. 
       FIG. 3C  shows the impedance curve  320 C that may correspond to a second type of blockage condition in which an object, such as a finger or other body part, partially blocks or obstructs the acoustic opening in the housing of the device. By way of illustration, this type of blockage may correspond to the example of  FIG. 2C , depicting an object  251  blocking the one or more of the set of acoustic openings  104 . The blockage may change or shift the resonant frequency of the acoustic transducer from 321 to 324 as illustrated by the impedance curve  320 C. This type of blockage condition may also distort and/or flatten the impedance curve  320 C due to air pressure blocking the one or more of the set of acoustic openings  104 . 
       FIGS. 3A-3C  illustrate that the impedances  322  are different based on the type and extent of the blockage. As such, the electronic device  100  (and/or the control circuitry  213 ) may apply power to the voice coil  210 , measure the impedance  322  at the reference or resonant frequency  321  (where the difference in impedance  322  would be the greatest if a blockage exists), and determine, based on a measured impedance or change in impedance, whether or not there is a blockage (such as liquid present in the acoustic passage). Based on the impedance  322  at the resonant frequency  321 , the electronic device  100  (and/or the control circuitry  213 ) may determine the type of the blockage, the extent of the blockage, and/or various characteristics of the blockage. 
     By way of example, the electronic device  100  (and/or the control circuitry  213 ) may determine that the impedance  322  corresponds to the relatively flat impedance curve  320 B of  FIG. 3B  rather than the impedance curve  320 C of  FIG. 3C . As such, the electronic device  100  (and/or the control circuitry  213 ) may determine that a foreign object is potentially contacting the diaphragm as opposed to an object merely blocking a port or opening. Determining that the type of blockage or obstruction corresponds to this type of blockage condition may be important in deciding whether or not to employ an evacuation measure or protocol. 
     By way of still another example, the electronic device  100  (and/or the control circuitry  213 ) may determine that the impedance  322  corresponds to the impedance curve  320 C of  FIG. 3C  rather than the impedance curve  320 B of  FIG. 3B . As such, the electronic device  100  (and/or the control circuitry  213 ) may determine that one or more of the set of acoustic openings  104  may be blocked but a foreign object is not present in the acoustic passage  206 . Determining that the type of blockage or obstruction corresponds to this type of blockage condition may be important in deciding to forgo or suppress an evacuation measure or protocol. 
     In some cases a degree of blockage, a type of foreign material or object, or an amount of foreign object ingress may be determined using an impedance measurement. In one example, the more that a port is obstructed or blocked, the lower the measured impedance and/or the greater the shift in the resonant frequency of the acoustic transducer. As such, the electronic device  100  (and/or the control circuitry  213 ) may estimate an amount of blockage of the port or opening. In another example, the more liquid that is present in the acoustic passage  206 , the lower the measured impedance at the reference or resonant frequency  321 . As such, the electronic device  100  (and/or the control circuitry  213 ) may estimate an amount of the liquid that is present based on the impedance  322 . 
       FIG. 4  is a simplified schematic of an acoustic module with a liquid detection module. In this example, the circuitry or controller includes a drive module  430  connected to an acoustic transducer  405 , which may include a voice coil or other similar element. The circuitry or controller may correspond to control circuitry  213  described above with respect to  FIGS. 2A-2C . The circuitry or controller may also include a liquid detection module  431 , which is configured to measure the impedance or changes in impedance of the acoustic transducer  405 . In some cases the liquid detection module  431  includes a high impedance sensing resistor and/or other impedance measuring device that is configured to measure small changes in impedance. In some cases the liquid detection module  431  is selectively activated to minimize any impact to performance of the acoustic module during ordinary use. In some cases, the liquid detection module  431  remains connected or activated and is configured with high-impedance elements that reduce the amount of current used by the liquid detection module  431  during ordinary use. In some cases, the liquid detection module  431  may be connected to the acoustic module  205  in parallel with the drive  430 . This may allow the liquid detection module  431  to detect impedance without interfering with the acoustic transducer  405 . However, it is understood that this is an example and other circuit configurations are possible and contemplated. 
     With reference again to  FIG. 2A , the electronic device  100  (and/or the control circuitry  213 ) may measure and/or evaluate the impedance of the voice coil  210  using one or more measurement protocols. For example, the impedance may be measured over a regularly repeating time interval or continuously (when the acoustic module  205  is not being used to produce or receive acoustic signals). If the impedance measurement includes a measurement while the acoustic module  205  is being operated at a resonant or reference frequency, the impedance measurement may not occur simultaneously with the normal sound-producing or sound-recording operations of the acoustic module  205 . In some cases, the impedance measurement is performed during or simultaneous to a sound-producing or sound-recording operation. 
     The impedance may also be measured upon the occurrence of a triggering condition. In some cases, one or more other sensors (e.g., the touch sensor  101  of  FIG. 1 ) may be used to determine if a blockage condition may exist, which may be used to trigger an impedance measurement. Exposure of the electronic device  100  to liquid may be detectable by the capacitive touch screen. If the capacitive touch screen detects such a possible exposure, the electronic device  100  (and/or the control circuitry  213 ) may receive a signal from the capacitive touch screen and determine to measure and/or evaluate the impedance of the voice coil  210 . In some implementations, the electronic device  100  (and/or the control circuitry  213 ) may measure and/or evaluate the impedance of the voice coil  210  prior to signaling the acoustic module  205  to produce sound waves (e.g., applying power to the voice coil  210 ). By way of another example, the electronic device  100  (and/or the control circuitry  213 ) may measure and/or evaluate the impedance of the voice coil  210  in response to receiving a user instruction to measure and/or evaluate. 
     Signals from various other sensors and/or other components may also be used to trigger measurement and/or evaluation. For example, the microphone may detect sound produced by the acoustic module  205  via the acoustic opening  103 . The electronic device  100  (and/or the control circuitry  213 ) may compare the detected sound to what the acoustic module  205  had been instructed to produce. If the detected sound is other than what is expected, the electronic device  100  (and/or the control circuitry  213 ) may measure and/or evaluate the impedance of the voice coil  210  under the assumption that the acoustic passage  206  may be partially or fully blocked. 
     Measuring impedance of the voice coil  210  involves applying power to the voice coil  210 . As a result, the diaphragm  209  may move and sound waves may be produced. This may be noticeable to a user, which may not always be desirable. As such, in some implementations, an ambient acoustic level or other sound level may be detected (such as using the microphone and/or another sound detector to determine a measured acoustic level) and measurement may be performed once the detected sound is above a threshold amount of sound. The threshold amount of sound may be an amount of sound below which, though not above which, the movement of the diaphragm  209  during measurement can be discerned by human hearing. In still other implementations, a user may be prompted to measure and/or evaluate and the electronic device  100  (and/or the control circuitry  213 ) may measure and/or evaluate upon receiving confirmation from the user. 
     In various implementations, the presence of liquid may detected based on a reduction of impedance over a range of frequencies that includes the resonant frequency as compared to a reference value. In such an implementation, the reference value may correspond to an operation of the voice coil  210  without the presence of liquid. The presence of liquid may be detected when the measured impedance is approximately equal to the impedance of the voice coil  210  when dry at a non-resonant frequency. 
     When the electronic device  100  detects a blockage, the electronic device  100  may perform one or more actions to remove the blockage which may be referred to as an evacuation measure or protocol. In some implementations, if the electronic device  100  detects that one or more of the set of acoustic openings  104  is blocked but liquid and/or other material or foreign contaminants (such as dirt, oil, and so on) is not in the acoustic passage  206 , the electronic device  100  may provide a notification to a user to clear the set of the acoustic openings  104 . 
     In various implementations, if the electronic device  100  determines that liquid and/or other material or foreign contaminants (such as dirt, oil, and so on) is present, the electronic device  100  may perform one or more actions to drive out, purge, and/or otherwise remove the liquid from the acoustic passage  206 . For example, the electronic device  100  may provide a notification to a user to remove the liquid. By way of another example, the electronic device  100  may activate a heating element that evaporates the liquid. 
     In various examples, the electronic device  100  may apply voltage to the voice coil  210  in order to vibrate and/or otherwise move the diaphragm  209 . Movement of the diaphragm  209  may drive the liquid from the acoustic passage  206 . In some situations, moving the diaphragm  209  to drive out liquid may be noticeable to a user, and may be undesirable. In some implementations, the electronic device  100  may apply the voltage such that sound waves produced are outside the range perceptible to human hearing (approximately 20 Hz-20 kHz). As such, the user would not notice driving out the liquid. In other implementations, the electronic device  100  may first prompt the user that driving out the liquid may be performed and perform driving out the liquid once the user confirms. In still other implementations, the electronic device  100  may use a sound detector such as the microphone to detect an ambient or other sound level and may drive out the liquid once sound is exceeding a threshold amount where the threshold amount would obscure the sound from driving out the liquid. 
     In various implementations, various frequencies may be used to drive out the liquid. In some cases, a sweep may be performed through a range of frequencies. The impedance may be monitored and driving out the liquid may be continued until the impedance (and/or monitoring of sound using the microphone or other sound detector) indicates that the liquid is gone, the sweep continuing through the range of frequencies as long as the impedance indicates the liquid is still present. In other cases, tones of one or more frequencies (such as tones previously found successful in removing liquid from the acoustic passage, which the control circuitry  213  may store in one or more non-transitory storage media) may be played until the impedance (and/or monitoring of sound using the microphone or other sound detector) indicates the liquid is gone, the frequencies and/or other properties varied as long as the liquid is still present. 
     In some implementations, a broadband or noise signal may be produced rather than a tone at a particular frequency or frequencies. In some cases, noise may be characterized as a broadband signal that includes multiple or a range of frequencies. Users are less likely to perceive a noise-type output as compared to a tone having a particular frequency or frequencies. As such, voltage applied to the acoustic transducer to use noise to drive out the liquid may be less noticeable to users even though produced at a volume level that may be otherwise perceptible. 
     Additionally, the electronic device may determine whether or not the electronic device has ever been exposed to a particular contaminant. For example, many warranties may be voided if a device has ever been immersed in and/or significantly exposed to water. As such, the electronic device may perform various actions upon detecting liquid in the acoustic passage  206 . 
     For example, the electronic device may be operable to respond to a query as to whether the electronic device has been exposed to contaminants such as water. Upon detecting liquid in the acoustic passage (e.g., acoustic passage  206  of  FIGS. 2A-2C ), the electronic device may utilize a communication component to notify a computing device (such as one maintained by or for a warrantee provider, manufacturer, retailer, and/or other entity) regarding the detection. Alternatively, the electronic device may store information regarding the detection in a non-transitory storage media and may provide such information when requested via the communication component, by a user, and the like. 
       FIG. 5  depicts a flow chart illustrating a first example method  500  for detecting liquid in an acoustic module using impedance and removing the liquid. The method  500  may be performed by the electronic devices or hardware configurations of  FIGS. 1, 2A-2C , and/or  4 . 
     At  510 , a device operates. For example, the device may be powered on and perform normal operations in accordance with a standard protocol or normal use. The flow proceeds to  520  where the device determines whether or not to detect a blockage. If not, the flow returns to  510  where the device continues to operate. Otherwise, the flow proceeds to  530 . 
     At  530 , the device measures the impedance of the acoustic transducer (e.g. a transducer having a voice coil). The flow then proceeds to  540  where the device evaluates the impedance of the acoustic transducer. The impedance of the acoustic transducer may be measured in one or more of the following ways. In one example, the impedance is measured at a reference frequency, which may correspond to the resonant or natural frequency of the acoustic transducer in a dry or unobstructed condition. Additionally or alternatively, an average, weighted average, or other composite impedance measurement may be computed over a predetermined frequency range. In some cases, a change in impedance over a predetermined time interval is measured. Various other techniques may be used to evaluate the impedance or a change in impedance against various values that correspond to different conditions, compare the impedance against an expected impedance, or otherwise characterize the impedance response of the acoustic transducer. 
     The flow then proceeds to  550  where the device determines if there is blockage based on the measured impedance. In particular, the device may determine if there is liquid or another foreign object present in a passage or on the diaphragm of the acoustic transducer based on the measured impedance. If it is determined that there is no blockage, the flow returns to  510  where the device continues to operate. Otherwise, the flow proceeds to  560 . 
     With regard to  550 , a blockage may be determined based on one or more of the following techniques for evaluating or analyzing the impedance. For example, a blockage condition may be detected if the peak impedance is reduce or lowered. A blockage condition may also be detected if the peak impedance is shifted or moved with respect to a reference frequency (e.g., the resonant frequency of an unimpeded speaker). In general, any aspect of an impedance response or curve for a given frequency or over a range of frequencies may be used to make the determination in accordance with operation  550 . Example analysis of the impedance or impedance response of a device are also described above with respect to  FIGS. 3A-3C . 
     At  560 , the device (and/or circuitry of the device) may employ an evacuation measure or protocol that attempts to drive out, purge, and/or otherwise remove the liquid. Attempting to drive out the liquid may include applying a drive signal, voltage signal, or drive voltage to the acoustic transducer to move the attached diaphragm. In some cases, an updated impedance measurement is taken while applying the drive signal. Based on the updated impedance measurement, the drive signal may be adjusted or stopped. The flow then returns to  550  where it is determined whether or not the liquid is still present. 
     Although the example method  500  is illustrated and described as including particular operations performed in a particular order, it is understood that this is an example. In various implementations, various orders of the same, similar, and/or different operations may be performed without departing from the scope of the present disclosure. 
     For example, the method  500  is illustrated and described as the device determining whether or not the liquid is still present after attempting to drive out the liquid. However, in various implementations, the device may return to  510  and continue to operate after attempting to drive out the liquid without determining whether the liquid is still present or not. 
       FIG. 6  depicts a flow chart illustrating a second example method  600  for detecting liquid in an acoustic module using impedance and removing the liquid. The method  600  may be performed by the electronic devices or hardware of  FIGS. 1, 2A-2C , and/or  4 . 
     At  610 , a device operates. The flow proceeds to  620  where the device determines whether or not to provide output using an acoustic module such as a speaker. For example, the output may include providing a notification, playing sound, and so on. If not, the flow returns to  610  where the device continues to operate. Otherwise, the flow proceeds to  630 . 
     At  630 , the device measures the impedance of an acoustic transducer of an acoustic module. The flow then proceeds to  640  where the device determines based on the impedance whether or not liquid is present in an acoustic passage or port associated with the acoustic module. If not, the flow proceeds to  650  where the device provides the output using the acoustic module before the flow returns to  610  and the device continues to operate. Otherwise, the flow proceeds to  660 . 
     At  660 , the device performs an evacuation measure or protocol that is configured to drive out, purge, and/or otherwise remove the liquid. The flow then returns to  640  where it is determined whether or not the liquid is still present. 
     Although the example method  600  is illustrated and described as including particular operations performed in a particular order, it is understood that this is an example. In various implementations, various orders of the same, similar, and/or different operations may be performed without departing from the scope of the present disclosure. 
     For example, the method  600  is illustrated and described as the device determining whether or not liquid is present in the acoustic passage. However, in various implementations, the device may determine whether or not various contaminants or materials are present as opposed to liquid. 
       FIG. 7  depicts a flow chart illustrating a third example method  700  for detecting liquid in an acoustic module using impedance and removing the liquid. The method  700  may be performed by the electronic devices of  FIGS. 1, 2A-2C , and/or  4 . 
     At  710 , a device operates. The flow proceeds to  720  where the device determines whether or not to measure the impedance of an acoustic transducer of an acoustic module. If not, the flow returns to  710  and the device continues to operate. Otherwise, the flow proceeds to  730 . 
     At  730 , the device determines whether or not ambient or other detected sound is above a threshold amount. The threshold amount may be an amount that would obscure or otherwise cover sound produced by measuring impedance of the acoustic transducer. If not, the flow returns to  730  where the threshold is again evaluated. Essentially, the device may wait until the threshold amount of sound is detected. Otherwise, the flow proceeds to  740 . 
     At  740 , the device measures the impedance of the acoustic transducer of the acoustic module. The flow then proceeds to  750  where the device determines based on the impedance whether or not liquid is present in an acoustic passage or port associated with the acoustic module. If not, the flow returns to  710  and the device continues to operate. Otherwise, the flow proceeds to  760 . 
     At  760 , the device employs an evacuation measure or protocol that is configured to drive out, purge, and/or otherwise remove the liquid. The flow then returns to  750  where it is determined whether or not the liquid is still present (such as using the impedance, monitoring sound waves produced by the diaphragm using one or more microphones, and so on). 
     Although the example method  700  is illustrated and described as including particular operations performed in a particular order, it is understood that this is an example. In various implementations, various orders of the same, similar, and/or different operations may be performed without departing from the scope of the present disclosure. 
     For example, the method  700  is illustrated as the device waiting until the detected sound meets the threshold amount. However, in various implementations, the device may continue to wait for a period of time before returning directly to  710  without measuring impedance. In other implementations, the device may wait for the period of time and then measure impedance regardless of sound levels. 
       FIG. 8  depicts a flow chart illustrating an example method  800  for detecting a blockage in an acoustic module using impedance and removing the blockage. The method  800  may be performed by the electronic devices or hardware of  FIGS. 1, 2A-2C , and/or  4 . 
     At  810 , a device operates. The flow proceeds to  820  where the device measures the impedance of an acoustic transducer of an acoustic module. The flow then proceeds to  830  where the device determines based on the impedance whether or not an acoustic passage or port associated with the acoustic module is blocked. If not, the flow returns to  810  and the device continues to operate. Otherwise, the flow proceeds to  840 . 
     At  840 , the device determines based on the impedance whether the block is caused by liquid or other material in the acoustic passage or whether an opening connecting the acoustic passage to an external environment is covered. If the opening is covered, the flow proceeds to  850 . Otherwise, the flow proceeds to  860 . 
     At  850 , after the device determines the opening is covered, the device outputs a notification to a user that the opening is covered. The flow then returns to  810  where the device continues to operate. 
     At  860 , after the device determines that liquid or other material is present, the device employs an evacuation measure or protocol that is configured to drive out, purge, and/or otherwise remove the liquid. The flow then returns to  810  where the device continues to operate. 
     Although the example method  800  is illustrated and described as including particular operations performed in a particular order, it is understood that this is an example. In various implementations, various orders of the same, similar, and/or different operations may be performed without departing from the scope of the present disclosure. 
     For example, the method  800  is illustrated and described as providing a notification to the user if the opening is covered, but not if liquid is present in the acoustic passage. However, in various implementations, the device may output a message to a user that liquid is present and then drive out the liquid upon receiving a confirmation from the user. 
       FIG. 9  depicts an alternative example of the electronic device  100  of  FIG. 2A . As contrasted with the electronic device  100  of  FIG. 2A , the electronic device  900  and/or the circuitry  913  may not move the diaphragm  909  using the acoustic transducer  910 . Instead, a transducer  940  may be signaled by the circuitry  913  via an electrical conduit  941  to evacuate or drive out the liquid. The transducer  940  may be disposed on the structure  907 . 
     The transducer  940  may be any kind of component operable to generate motion to drive out the liquid from the acoustic passage  906 . For example, the transducer  940  may include a diaphragm that can be vibrated and/or otherwise moved to drive out the liquid. The transducer  940  may vibrate such a diaphragm so as to not produce sound waves perceptible to a human. By way of another example, the transducer  940  may include piezoelectric material operable to deflect, deform, and/or otherwise move to drive out the liquid. In still another example, the transducer  940  may include a flap or other mechanism that is moveable to drive out the liquid. Various transducer  940  configurations are possible and contemplated. 
     As described above and illustrated in the accompanying figures, the present disclosure relates to detection of liquid in an acoustic module, such as a speaker or microphone, using impedance and/or removal of the liquid. The acoustic module includes an acoustic transducer coupled to a diaphragm. The diaphragm faces an acoustic passage through which sound waves produced or received by the diaphragm travel. Blockages in the acoustic passage (such as liquid in the passage contacting the diaphragm, a finger covering an acoustic opening connecting the acoustic passage to an external environment, and so on) alter the impedance of the acoustic transducer. By measuring and evaluating the impedance, the acoustic module and/or an associated electronic device determines whether or not a blockage is present. 
     In the present disclosure, the methods disclosed may be implemented as sets of instructions or software readable by a device. Further, it is understood that the specific order or hierarchy of steps in the methods disclosed are examples of sample approaches. In other embodiments, the specific order or hierarchy of steps in the method can be rearranged while remaining within the disclosed subject matter. The accompanying method claims present elements of the various steps in a sample order, and are not necessarily meant to be limited to the specific order or hierarchy presented. 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not targeted to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.

Metadata:
Filing Date: 20160824
Publication Date: 20190219
Grant Date: 20190219
Priority Date: 20160824
Inventors: VITT, Nikolas T.
DAVE, RUCHIR M
LIPPERT, Jesse A.
BOOZER, BRAD G.
EVANS, NEAL D.
Wilkes, Jr., David S.
Assignee: APPLE INC
CPC Classifications: [{"code": "G01H15/00", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01N29/028", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01H13/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01H15/00", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01H15/00", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R1/345", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R29/001", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R2499/11", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01N29/028", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01H13/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R2499/11", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/345", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R29/001", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 61242155