PATENT DOCUMENT

Publication Number: US-10728646-B2
Application Number: US-201815933090-A
Country: US
Kind Code: B2

Title: Earbud devices with capacitive sensors

Abstract:
An earbud may have a housing with an ear portion and an elongated out-of-ear portion that protrudes away from the ear portion. A speaker may be aligned with a speaker port in the ear portion and may emit sound for a user. Audio playback functions and other operations may be controlled using a controller in the earbud. The controller may gather capacitive sensor data and other data and may use this data in identifying an operating mode of the earbud. Using information such as whether the earbud is in an in-ear state or an out-of-ear state or other sensor data, the controller may take actions such as pausing or resuming audio playback or adjusting playback volume. The capacitive sensor data can be gathered using capacitive sensing electrodes located on the ear portion and the stalk portion of the earbud.

Claims:
What is claimed is: 
     
       1. An earbud, comprising:
 a housing having an ear portion and an out-of-ear portion that protrudes from the ear portion; 
 a controller; and 
 capacitive sensing circuitry coupled to the controller, wherein the capacitive sensing circuitry includes:
 ear electrodes in the ear portion; and 
 out-of-ear electrodes in the out-of-ear portion, wherein the capacitive sensing circuitry is configured to produce ear sensor data from the ear electrodes and out-of-ear sensor data from the out-of-ear electrodes, wherein the out-of-ear electrodes are uncovered when the earbud is located in a user&#39;s ear, and wherein the controller is configured to determine an operating state of the earbud based on the ear sensor data and the out-of-ear sensor data, and wherein the out-of-ear sensor data serves as reference data that is substracted from the ear sensor data. 
 
 
     
     
       2. The earbud defined in  claim 1  wherein the controller is configured to determine the operating state of the earbud by applying a classification process to the ear sensor data and the out-of-ear sensor data. 
     
     
       3. The earbud defined in  claim 2  wherein the controller is configured to determine whether the operating state of the earbud is an in-ear operating state or an in-finger operating state by applying the classification process to the ear sensor data and the out-of-ear sensor data. 
     
     
       4. The earbud defined in  claim 3  further comprising a speaker in the ear portion, wherein the controller is configured to pause audio playback with the speaker in response to detecting that the operating state changed from the in-ear operating state to the in-finger operating state. 
     
     
       5. The earbud defined in  claim 4  further comprising a flexible printed circuit extending along an interior surface of a wall of the housing, wherein the flexible printed circuit includes metal traces forming the ear electrodes and the out-of-ear electrodes. 
     
     
       6. The earbud defined in  claim 5  wherein the flexible printed circuit further comprises a ground electrode. 
     
     
       7. The earbud defined in  claim 6  wherein the flexible printed circuit further comprises an active shield electrode. 
     
     
       8. The earbud defined in  claim 7  wherein the active shield electrode is interposed between the ground electrode and the metal traces. 
     
     
       9. The earbud defined in  claim 7  wherein the capacitive sensing circuitry comprises a capacitive sensor integrated circuit and wherein at least a portion of the ground electrode is interposed between the capacitive sensor integrated circuit and the active shield electrode. 
     
     
       10. The earbud defined in  claim 5  wherein the interior surface is curved and wherein the flexible printed circuit is wrapped at least partly about an axis. 
     
     
       11. The earbud defined in  claim 1  wherein the ear electrodes and the out-of-ear electrodes extend across all of the housing including the ear portion and the out-of-ear portion. 
     
     
       12. An earbud operable in an operating state, comprising:
 a housing having an ear portion configured to be received in an ear and having an elongated out-of-ear portion that protrudes from the ear portion and that extends along a longitudinal axis; 
 a speaker in the ear portion that is configured to emit sound through a speaker port opening in the ear portion; 
 ear capacitive sensing electrodes in the ear portion; 
 out-of-ear capacitive sensing electrodes in the out-of-ear portion that wrap around the longitudinal axis; and 
 control circuitry configured to determine the operating state by classifying capacitive sensor data from the ear capacitive sensing electrodes and the out-of-ear capacitive sensing electrodes, wherein the control circuitry determines that the operating state is an in-ear operating state when the ear capacitive sensing electrodes are contacted and the out-of-ear capacitive sensing electrodes are uncontacted. 
 
     
     
       13. The earbud defined in  claim 12  further comprising:
 wireless communications circuitry configured to receive audio data to play with the speaker; and 
 a flexible printed circuit that conforms to an inner surface of the housing, wherein the out-of-ear capacitive sensing electrodes are formed on the flexible printed circuit. 
 
     
     
       14. The earbud defined in  claim 13  wherein the ear capacitive sensing electrodes are formed on the flexible printed circuit. 
     
     
       15. The earbud defined in  claim 14  further comprising an active shield and a ground on the flexible printed circuit, wherein at least some of the active shield is interposed between the ground and the out-of-ear capacitive sensing electrodes. 
     
     
       16. The earbud defined in  claim 15  wherein at least some of the active shield is interposed between the ground and the ear capacitive sensing electrodes. 
     
     
       17. The earbud defined in  claim 15  wherein the control circuitry includes a capacitive sensor integrated circuit coupled to the ear capacitive sensing electrodes and the out-of-ear capacitive sensing electrodes. 
     
     
       18. The earbud defined in  claim 15  wherein the flexible printed circuit has a single common active shield for all of the ear capacitive sensing electrodes and out-of-ear capacitive sensing electrodes. 
     
     
       19. The earbud defined in  claim 12  wherein the control circuitry is configured to pause audio playback with the speaker in response to determine the operating state has transitioned from the in-ear operating state to an out-of-ear operating state. 
     
     
       20. The earbud defined in  claim 12  further comprising a non-capacitive-sensing sensor, wherein the control circuitry is configured to determine the operating state using data from the non-capacitive sensing sensor. 
     
     
       21. An earbud, comprising:
 a housing having an ear portion and an elongated out-of-ear portion that protrudes from the ear portion; 
 a speaker in the ear portion that is aligned with a speaker port opening in the ear portion; 
 capacitive sensing electrodes that include first electrodes in the ear portion and second electrodes in the out-of-ear portion, wherein the first electrodes produce first capacitive sensor data and the second electrodes produce second capacitive sensor data; and 
 control circuitry configured to determine an operating state of the earbud at least partly by subtracting the second capacitive sensor data from the first capacitive sensor data, wherein the second electrodes are uncovered when the operating state is an in-ear operating state. 
 
     
     
       22. The earbud defined in  claim 21  further comprising a flexible printed circuit wrapped about an axis, wherein the flexible printed circuit has metal traces configured to form the first and second electrodes. 
     
     
       23. The earbud defined in  claim 22  wherein the metal traces include an active shield electrode on the flexible printed circuit and a ground electrode on the flexible printed circuit, wherein the active shield electrode is interposed between the ground electrode and the first and second electrodes and wherein the control circuitry is configured to detect finger touch gestures on the out-of-ear portion using the second electrodes. 
     
     
       24. The earbud defined in  claim 21  further comprising a non-capacitive-sensing sensor, wherein the control circuitry is further configured to determine the operating state using non-capacitive-sensing sensor data from the non-capacitive-sensing sensor.

Description:
BACKGROUND 
     This relates generally to electronic devices, and, more particularly, to electronic devices such as earbuds. 
     Electronic devices such as earbuds contain audio circuitry and speakers for playing audio content for a user. In a typical scenario, the earbuds receive audio content wirelessly from a cellular telephone.10 
     It can be challenging to perform music playback operations and other device functions using a pair of earbuds. In some situations, a user&#39;s cellular telephone is not accessible, making it difficult to pause and resume audio content when desired. Providing user input to the earbuds to control functions such as audio playback can be difficult due to their small size. 
     SUMMARY 
     Audio playback functions and other operations may be controlled using a controller in an earbud that analyzes sensor data to determine the operating state of the earbud. If, as an example, a user removes an earbud from the user&#39;s ear, the controller can automatically pause audio playback. 
     An earbud may have a housing. The housing may have an ear portion configured to be received within an ear of a user. The housing may also have an elongated stalk portion that protrudes away from the ear portion. Capacitive sensor electrodes may be formed both on the ear portion and the stalk portion. 
     During operation, the controller may gather capacitive sensor data from the capacitive sensor electrodes and may gather data from non-capacitive-sensing sensors. Using this data, the controller can classify an operating mode of the earbud. 
     The controller may take actions such as pausing or resuming audio playback using the results of classification operations such as information on whether an earbud is in an in-ear state or an in-finger (out-of-ear) state. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an illustrative electronic device in accordance with an embodiment. 
         FIG. 2  is a rear perspective view of an illustrative ear bud in accordance with an embodiment. 
         FIG. 3  is a front perspective view of the illustrative ear bud of  FIG. 3  in accordance with an embodiment. 
         FIG. 4  is a side view of an illustrative ear bud showing how a flexible printed circuit that includes capacitive sensor circuitry can be mounted within the interior of an earbud housing for the ear bud in accordance with an embodiment. 
         FIG. 5  is a perspective view of an illustrative flexible printed circuit with capacitive sensor electrodes in accordance with an embodiment. 
         FIGS. 6 and 7  are cross-sectional side views of portions of an illustrative flexible circuit with capacitive sensor electrodes, a ground electrode, and an active shield electrode in accordance with an embodiment. 
         FIG. 8  is a cross-sectional side view of a portion of an ear bud having capacitive sensor circuitry on a flexible printed circuit that is bent by wrapping the flexible printed around an axis so that the flexible printed circuit and the capacitive sensor circuitry on the flexible printed circuit conform to a curved inner surface of a housing wall in accordance with an embodiment. 
         FIG. 9  is a graph showing how control circuitry in an ear bud can detect when the ear bud is in the ear of a user in accordance with an embodiment. 
         FIG. 10  is a flow chart of illustrative operations involved in using an ear bud in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An electronic device such as an earbud may be provided with sensors. The sensors may include capacitive sensing circuitry and other sensing circuitry that monitors how the device is positioned relative to the body of a user. The sensors may, for example, include capacitive sensing circuitry and/or other sensors for detecting when the device is positioned in the user&#39;s ear. Based on information from the sensors, suitable action can be taken by control circuitry in the device. For example, audio playback may be controlled. 
     In general, the electronic device may be any suitable type of device that includes sensors. Illustrative configurations in which the electronic device is an earbud are sometimes described herein as an example. 
       FIG. 1  is a schematic diagram of an illustrative electronic device such as an earbud. As shown in  FIG. 1 , earbud  10  may communicate wirelessly with external equipment such as electronic device  14  using wireless link  28 . Wireless signals for link  28  may be light-based signals, may be acoustic signals, and/or may be radio-frequency signals (e.g., wireless local area network signals, Bluetooth® signals, radio-frequency signals in cellular telephone band, signals at 60 GHz, near field communications signals, etc.). Earbud  10  and device  14  may have antennas and wireless transceiver circuitry for supporting wireless communications over link  28  (e.g., input-output circuitry in earbud  10  such as devices  22  may include antennas, wireless transceiver circuitry, and/or other communications circuitry for supporting wireless communications over link  28 ). Earbud  10  may have the same capabilities as device  14  (i.e., earbud  10  and device  14  may be peer devices) or earbud  10  may include fewer resources or more resources than device  14 . 
     Illustrative earbud  10  of  FIG. 1  has control circuitry  20 . Control circuitry  20  may include storage and processing circuitry for supporting the operation of earbud  10 . The storage and processing circuitry may include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in control circuitry  20  may be used to control the operation of earbud  10  (see, e.g., controller  20 B). The processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio chips (e.g., chips with audio amplifiers that can be selectively assigned to play right channel audio in a first ear speaker of earbud  10  and left channel audio in a second ear speaker or vice versa), application specific integrated circuits, etc. 
     Earbud  10  may include capacitive sensors and/or other sensors  26 . Sensors  26  may include optical sensors such as optical proximity sensors (e.g., sensors that include an infrared light source such as an infrared light emitting diode or infrared laser and a corresponding infrared light detector to measure how much of the emitted infrared light is reflected from external objects), accelerometers and/or other sensors for detecting taps against device  10  and for detecting motion and orientation for earbud  10 , magnetic sensors, force sensors, microphones, light detectors, etc. 
     As shown in  FIG. 1 , earbud  10  may include a capacitive sensor (capacitive sensing circuitry) having electrodes  40 . Control circuitry  20  may include circuitry for providing signals to electrodes  40  (e.g., to drive electrodes and/or shields) and may include circuitry for gathering signals from electrodes  40 . For example, control circuitry  20  may include capacitive sensing circuit  20 A (e.g., an integrated circuit with capacitive sensor control circuitry). 
     Capacitive sensor electrodes  40  may include sense electrodes  42  and additional electrodes such as active shield electrode  44  and ground electrode  46 . Ground electrode  46  may be associated with the ground of capacitive sensing circuitry  20 A. When an electrode  42  is being driven with alternating-current drive signals, the same alternating-current signal may be applied to active shield electrode  44  (e.g., electrode  44  may be actively driven). This type of sensing arrangement, in which capacitive sensing circuit  20 A is used in applying drive signals to electrodes  42 , a ground signal to electrode  46 , and an active shield signal to active shield electrode  44 , which is sometimes referred to as a self-capacitance sensing arrangement, is illustrative. If desired, other approaches may be used in gathering capacitive sensor measurements from electrodes  40  (e.g., mutual capacitance techniques). 
     Input-output circuitry in earbud  10  such as input-output devices  22  may be used to allow data to be supplied to earbud  10  and to allow data to be provided from earbud  10  to external devices. Input-output devices  22  may include buttons, touch sensors, haptic output devices, image sensors, sensors  26  (e.g., ambient light sensors, magnetic sensors, force sensors, gyroscopes, accelerometers, optical proximity sensors, and other sensors), light-emitting diodes and other status indicators, data ports, displays, etc. Input-output devices  22  may include audio components such as microphones and speakers such as speaker  24 . 
     A user can control the operation of earbud  10  by supplying commands using capacitive sensing circuitry and/or input-output devices  22 . For example, a user can provide tap input (tap gestures) by tapping on earbud  10  with a finger or sliding the finger along the case of the earbud close to sensing electrodes  42 . Tap input may be monitored using an accelerometer or other motion sensor in devices  22 . The user may also supply voice commands that are gathered using a microphone in devices  22 . Electrodes  42  may include electrodes that can be touched by a user&#39;s finger to supply touch commands (e.g., swipe gestures, tap gestures, other finger touch gestures, etc.). Control circuitry  20  can also make capacitance measurements with electrodes  40  to determine whether electrodes  40  are in contact with portions of the user&#39;s ear and thereby determine whether earbud  10  is in the user&#39;s ear or is out of the user&#39;s ear. 
     Control circuitry  20  may be used to run software on earbud  10  such as operating system code and applications. During operation of earbud  10  in a system (e.g., a system that includes a pair of earbuds  10  and a cellular telephone, watch, tablet computer, laptop computer, and/or other device  14  that supplies audio to the earbuds), the software running on control circuitry  20  may use the capacitive sensor formed from electrodes  40  to gather information on whether any of electrodes  40  are being touched by the user and/or whether any of electrodes  40  are detecting that earbud  10  is in or is not in the user&#39;s ear. This software may also gather and use other information such as accelerometer signals from sensors  26  (e.g., motion signals indicating that earbud  10  is in use by a user or is at rest and not in use) and may gather and use other information from input-output devices  22  in earbud  10  (e.g., button input, voice input, and/or other input from a user). 
     If desired, electrodes  40  may be incorporated into devices other than earbuds. for example, electrodes  40  may be used in a computing device such as a laptop computer, a computer monitor containing an embedded computer, a tablet computer, a cellular telephone, a media player, or other handheld or portable electronic device, a smaller device such as a wrist-watch device (e.g., a watch with a wrist strap), a pendant device, a headphone or earpiece device, a device embedded in eyeglasses or other equipment worn on a user&#39;s head, or other wearable or miniature device, a television, a computer display that does not contain an embedded computer, a gaming device, a navigation device, an embedded system such as a system in which electronic equipment with a display is mounted in a kiosk or automobile, furniture, fabric-based items such as pillows and clothing, equipment that implements the functionality of two or more of these devices, or other electronic equipment. The use of electrodes  40  to form capacitive sensing circuitry (e.g., a capacitive sensor array) in earbud  10  is merely illustrative. 
       FIGS. 2 and 3  are respectively front and rear perspective views of an illustrative earbud. As shown in  FIGS. 2 and 3 , earbud  10  may have a housing such as housing  12 . Housing  12  may have one or more housing walls formed from polymer, glass, ceramic, metal, other materials, and/or combinations of these materials. The inner surfaces of the housing wall forming housing  12  may have planar portions and/or curved portions. 
     Openings may be formed in housing  12 . For example, housing  12  may include speaker port opening  24 P to allow sound that is produced by speaker  24  to exit housing  12 . Housing  12  (and earbud  10 ) may have an ear portion such as ear portion  50  configured to be received within the ear of a user and may have a stalk portion such as elongated stalk portion  52  (sometimes referred to as an out-of-ear portion) that is configured to protrude away from ear portion  50  and out of the user&#39;s ear. A user may hold stalk portion  52  when placing ear portion  50  into the user&#39;s ear. A user may also provide finger touch gestures (e.g., swipes, etc.) to the capacitive sensing circuitry on stalk portion  52  and to any exposed portions of the capacitive sensing circuitry on ear portion  50  while other parts of ear portion  50  are inserted into the user&#39;s ear. 
     Capacitive sensing electrodes  40  may extend across both ear portion  50  and stalk portion  52  of housing  12  (e.g., electrodes  40  may be formed on the inner surface of a polymer housing wall or other dielectric housing structures so that these electrodes can gather sensor measurements from most or all exposed outer surfaces of housing  12  in both ear portion  50  and stalk portion  52  through the dielectric housing structures). Housing  12  may have a wall thickness of at least 0.1 mm, at least 0.5 mm, less than 2 mm, less than 1 mm, less than 0.6 mm, or other suitable wall thickness. As shown in the examples of  FIGS. 2 and 3 , there may be an array of multiple capacitive sensor electrodes  42  overlapped by the surface of housing  12  in both ear portion  50  and in stalk portion  52 . Electrodes  42  may be formed on an outer surface of housing  12 , may be formed on or placed near an inner surface of a housing wall forming housing  12 , and/or may be embedded within the polymer or other material forming housing  12 . Configurations in which electrodes  42  are covered by housing wall structures or cosmetic dielectric coatings may help hide electrodes  42  from view by a user. There may be multiple electrodes  42  in ear portion  50  and these electrodes may run around the perimeter of ear portion  50  (e.g., by running around the inner curved surface of ear portion  50 . There may also be multiple electrodes  42  on stalk portion  52 . 
     During operation, signals from the electrodes  42  in ear portion  50  and stalk portion  52  can be monitored to determine whether ear bud  10  is in the user&#39;s ear or is not in the user&#39;s ear. In addition to serving as a touch sensor that receives user input, the capacitive electrodes  42  on stalk portion  52  can be used to produce reference (baseline) measurements that can be effectively subtracted from the measurements made by the capacitive electrodes  42  on ear portion  50 . This helps improve the accuracy of the measurements made with electrodes  42  in ear portion  50 . For example, temperature drift effects or active shield/ground loading by external objects may be present both in the electrodes on portion  50  and the electrodes in portion  52 , whereas capacitance readings related to contact between the electrodes and the user&#39;s ear will only be present on the electrodes on ear portion  50 . The electrode data in portion  52  can therefore serve as reference data that can be removed from the electrode data in portion  50  (e.g., by subtraction or other suitable processing operations during operating mode classification). Processing the sensor readings from electrodes  42  in portions  50  and  52  in this way therefore can help minimize or eliminate possible sources of error in the capacitive measurements made on the user&#39;s ear. 
     Electrodes  40  such as electrodes  42  can be formed on a single substrate or multiple substrates that are coupled together (e.g., using solder, conductive adhesive, etc.) and may share a single active shield or have multiple active shields for all electrodes. In the illustrative example of  FIG. 4 , electrodes  42  have been formed on a single flexible printed circuit  54 . Capacitive sensor circuit  20 A (e.g., an integrated circuit) can be mounted to flexible printed circuit  54  over ground electrode  46  (e.g., so that circuit  20 A overlaps ground. 
     As shown in  FIG. 5 , flexible printed circuit  54  can be wrapped around longitudinal axis  64  (e.g., on the inner curved surface of the housing wall forming housing  12 ) so that some of electrodes  42  form an electrode array in stalk portion  52  and some of electrodes  42  form an electrode array in ear portion  50 . Electrodes  42  may be wrapped around axis  64 , so that capacitive sensor measurements can be made on all exposed surfaces of earbud  10  when flexible printed circuit  54  is mounted within housing  12 . Electrodes  42  may make capacitive measurements through housing  12  (e.g., through an opaque polymer wall or other dielectric housing wall having a thickness of at least 0.1 mm, at least 0.3 mm, at least 0.7 m, at least 1 mm, less than 4 mm, less than 2 mm, or other suitable thickness). Electrodes  42  and other electrodes  40  for the capacitive sensing circuitry of earbud  10  may be formed from metal traces on one or more layers of polymer in flexible printed circuit  54 . 
     As shown in the illustrative cross-sectional side view of a portion of flexible printed circuit  54  in  FIG. 6 , sense electrodes  42  may overlap active shield electrode  44 . For example, sense electrodes  42  and shield electrode  44  may be formed on opposing sides of a flexible printed circuit substrate layer such as substrate layer  58 . 
       FIG. 7  is a cross-sectional side view of another illustrative portion of flexible printed circuit  54 . In the portion of flexible printed circuit  54  shown in  FIG. 7 , capacitance sensor circuit  20 A (e.g., an integrated circuit) has been mounted to a first side of flexible printed circuit substrate layer  58  and sense electrodes  42  have been mounted to a second side of flexible printed circuit substrate layer  58 . Ground electrode  46  (sometimes referred to as chip ground) may be overlapped by capacitance sensor circuit  20 A and may be interposed between circuit  20 A and electrodes  42 . Active shield layer  44  may be overlapped by circuit  20 A and by electrodes  42  and may be interposed between ground  46  and electrodes  42 . 
       FIG. 8  is a cross-sectional end view of ear bud  10  showing how electrodes  42  may extend circumferentially around the curved inner surface of the housing wall forming housing  12 . In this arrangement, the flexible printed circuit on which electrodes  42 ,  44 , and  46  are formed may be wrapped in a curved shape to conform to the curved inner surface. 
     Active shield layer  44  may be interposed between ground  46  and electrodes  42 . There are four electrodes  42  arrayed around the circumference of housing  12  in the example of  FIG. 8  (which may be, for example, a portion of housing  12  in ear portion  50  or a portion of housing  12  in stalk portion  52 ). If desired, more than four or fewer than four electrodes may extend across housing  12  (e.g., wrapping around axis  64  of  FIG. 5  on the interior of a housing wall) at a given position along its length. 
     During operation, control circuitry  20  (e.g., controller  20 B) can use the capacitive sensing circuitry formed from capacitive sensing circuit  20 A and electrodes  40  to gather capacitive sensor input. In particular, earbud  10  can gather capacitive sensor data from electrodes  42  in ear portion  50  and from electrodes  42  in stalk portion  52  of ear bud  10 . These sensor readings can be used in determining which actions to take in ear bud  10 . Control circuitry  20  may, for example, use classification techniques such as a decision tree classification techniques to determine whether electrodes  42  are supplying data indicative of a baseline (not contacted) state (e.g., when ear bud  10  is resting on a table), an in-ear state (e.g., a state in which electrodes  42  in ear portion  50  detect contact or close proximity with the ear of a user while electrodes  42  in stalk portion  52  are uncontacted because stalk portion  52  is protruding out of the user&#39;s ear), or an in-finger state or other out-of-ear state in which electrodes  42  in ear portion  50  are not contacted (because portion  50  is not in the user&#39;s ear) and in which electrodes  42  in portion  52  are contacted or in close proximity with the user&#39;s fingers (because the user is holding portion  52  in the user&#39;s fingers). Decision tree classification, and/or other types of classification can be used by control circuitry  20  to determine the state of ear bud  10  based on capacitor data from electrodes  42 . Classification of the operating state of earbud  10  based on signals from electrodes  40  generally involves analysis of capacitive sensor data from electrodes  42  in both ear portion  50  and in stalk (out-of-ear) portion  52 . Consider, as an illustrative example, a classification technique that computes a ratio of the highest magnitude signals E from electrodes  42  in ear portion  50  to that of the lowest magnitude signal K from electrodes  42  in stalk portion  52 . A graph of ratio E/K versus time for two illustrative operating scenarios is shown in  FIG. 9 . In the scenario of curve  62 , earbud  10  is never in the user&#39;s ear, so electrodes  42  in ear portion  50  and stalk portion  52  tend to have comparable values and the ratio E/K does not exceed threshold TH. Control circuitry  20  can therefore conclude that earbud  10  is not in the user&#39;s ear. In the scenario of curve  60 , earbud  10  is operated out of the user&#39;s ear during times before t 1  and times after t 2 . As a result, ratio E/K is below threshold value TH at times before t 1  and after t 2  and control circuitry  20  can conclude that earbud  10  is not in the user&#39;s ear before t 1  and after t 2 . At times t between t 1  and t 2 , the ratio E/K exceeds TH, so control circuitry  20  can conclude that earbud  10  has been placed in the user&#39;s ear. Circuitry  20  can, for example, detect the out-of-ear to in-ear transition at time t 1  and the in-ear to out-of-ear transition at time t 2 . Because stalk portion  50  is not in the user&#39;s ear during the period t 1  to t 2 , electrodes  42  on stalk K are not receiving any signals from contact with an external object and can therefore serve as reference electrodes. Computation of the ratio E/K in this arrangement reduces the impact of potential sources of measurement error such as temperature drift, because such sources of error occur equally on both the electrodes of ear portion  50  and the electrodes of stalk portion  52 . 
     As this illustrative example demonstrates, use of capacitive sensor data from both ear electrodes and stalk electrodes can enhance the accuracy of operating state classification operations relative to techniques that examine only data from ear electrodes. The use of a ratio (e.g., E/K) in classifying the state of ear bud  10  is merely illustrative. Any suitable classification technique may be used in processing ear and stalk capacitive sensor data if desired. 
       FIG. 10  is a flow chart of illustrative operations involved in using earbud  10 . During the operations of block  70 , control circuitry  20  uses capacitive sensor circuitry such as circuit  20 A and electrodes  40  (including electrodes  42  in ear portion  50  and electrodes  42  in stalk portion  52 ) to make capacitive sensor measurements. With one illustrative arrangement (sometimes referred to as a self-capacitance method), all the electrodes including electrodes  42  and the active shield are to be driven with similar waveforms, and the capacitance of each line vs. gnd of the circuit is measured (except the one being measured, all other electrodes will be acting as active shield or gnd). This process of capacitance measurement can be performed sequentially, or in parallel for all electrodes  42 . Self-capacitance capacitive sensing techniques may provide larger sensing range than mutual capacitance measurement techniques. 
     With an illustrative mutual capacitance arrangement, control circuitry  20  can drive all but one of sensor electrodes  42  and active shield  44  with drive signals while measuring resulting signals on a non-driven sensor electrode  42 . Control circuitry  20  can cycle through each of electrodes  42  in ear portion  50  and stalk portion  52  in this way to gather capacitive sensor data from all electrodes  42 . 
     Once data has been gathered from all sensor electrode  42  using self-capacitance or mutual capacitance measurement techniques, processing may proceed to the operations of block  72 . 
     During the operations of block  72 , control circuitry  20  can use the capacitive sensor data to classify the operating state of earbud  10  and/or to gather finger touch gestures made by a user&#39;s finger on stalk portion  52 . For example, control circuitry  20  can perform classification operations on the gathered sensor data from electrodes  42  to identify the current operating state of earbud  10 . In particular, a classification algorithm can be applied to the capacitive sensor data gathered during the operations of block  70  so that control circuitry  20  can determine the operating state of earbud  10  (e.g., in a case, resting on a table, in a user&#39;s ear, being held in a user&#39;s fingers and/or hand, and/or other operating states). The operations of  FIG. 10  may be performed continuously, so that control circuitry  20  can detect any changes to the operating state of earbud  10  (e.g., so that control circuitry  20  can detect when earbud  10  is placed into a user&#39;s ear, remove from the user&#39;s ear, placed in a case, etc.) and so that control circuitry  20  can continually respond to user finger gestures (e.g., gestures on stalk portion  52 ). 
     During the operations of block  74 , control circuitry  20  can take suitable action based on the detected operating state of earbud  10 . If, as an illustrative example, control circuitry  20  detects that a user has removed earbud  10  from the user&#39;s ear and is now holding earbud  10  in the user&#39;s fingers, control circuitry  20  can pause audio that was being played for the user with speaker  24 . The audio playback can be automatically resumed when the user replaces earbud  10  in the user&#39;s ear. When control circuitry  20  detects that earbud  10  is in a case or is resting on a table, earbud  10  can be placed in a low power sleep state. 
     Classification operations such as the operations of blocks  70  and  72  can use sensor data from one or more different types of sensors  26  in addition to capacitive sensors (e.g., from one or more non-capacitive-sensing sensors). As an example, control circuitry  20  can gather accelerometer data or other data during the operations of block  70  using non-capacitive-sensing sensors  26 . This data may, as an example, indicate whether earbud  10  is moving in a way that is associated with in-ear operations, is resting (e.g., as when earbud  10  is lying on a table), etc. To enhance classification accuracy, accelerometer data, infrared light sensor data (e.g., light-based proximity and/or touch data), and/or other sensor data (e.g., from motion sensors, temperature sensors, force sensors, proximity and/or touch sensors, etc.) can be used in classifying the operational state of earbud  10 . For example, control circuitry  20  can require that there be at least a small amount of detected movement from an accelerometer to classify earbud  10  as being operated in a user&#39;s ear, even if the ratio of ear capacitive sensor measurement to stalk capacitive sensor measurements (or other capacitive sensor data being classified) indicates that earbud  10  might be in a user&#39;s ear. Sensor data from sensors  26  such as these may be gathered using sensors that are located in ear portion  50  and/or in stalk  52 . As an example, light-based sensor data can be gathered using light sensors (e.g., light-based sensors that detect the presence of external objects) in portions  50  and  52 . 
     
       
         
           
               
             
               
                   
               
               
                 Table of Reference Numerals 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 10 
                 Earbud 
                 12 
                 Housing 
               
               
                 14 
                 Device 
                 20 
                 Circuitry 
               
               
                 20A 
                 Capacitive sensing 
                 20B 
                 Controller 
               
               
                   
                 circuit 
                   
                   
               
               
                 22 
                 Input-output devices 
                 24 
                 Speaker 
               
               
                 24P 
                 Speaker port opening 
                 26 
                 Sensor 
               
               
                 28 
                 Link 
                 40 
                 Electrodes 
               
               
                 42 
                 Electrodes 
                 44 
                 Shield electrodes 
               
               
                 46 
                 Ground electrodes 
                 50 
                 Ear portion 
               
               
                 52 
                 Stalk portion 
                 54 
                 Flexible printed 
               
               
                   
                   
                   
                 circuit 
               
               
                 58 
                 Substrate layer 
                 64 
                 Axis 
               
               
                   
               
            
           
         
       
     
     The foregoing is merely illustrative and various modifications can be made to the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20180322
Publication Date: 20200728
Grant Date: 20200728
Priority Date: 20180322
Inventors: MOHAMMADI, SAEED
SHUI, TAO
Assignee: APPLE INC
CPC Classifications: [{"code": "H03K2217/960755", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/1016", "inventive": true, "first": false, "tree": "[]"}, {"code": "H03K2217/960765", "inventive": false, "first": false, "tree": "[]"}, {"code": "H03K2217/960755", "inventive": false, "first": false, "tree": "[]"}, {"code": "H03K17/962", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/1041", "inventive": true, "first": false, "tree": "[]"}, {"code": "H03K17/9622", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R1/1016", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/1041", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R1/1016", "inventive": true, "first": false, "tree": "[]"}, {"code": "H03K17/962", "inventive": true, "first": false, "tree": "[]"}, {"code": "H03K2217/960755", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/1041", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 67983850