PATENT DOCUMENT

Publication Number: US-9344792-B2
Application Number: US-201213689567-A
Country: US
Kind Code: B2

Title: Ear presence detection in noise cancelling earphones

Abstract:
An electronic device may be coupled to an accessory such as a pair of earphones. The earphones may have noise cancellation features that may be implemented using noise cancellation circuitry in the earphones or in the electronic device. The earphones may have ear presence sensor structures that determine whether speakers in the earphones are present at the ears of a user. In one suitable embodiment, control circuitry in the earphones may be used to adjust noise cancellation circuitry in the earphones based on information from the ear presence sensor structures. For example, the control circuitry may deactivate noise cancellation circuitry in response to receiving information from the ear presence sensor structures indicating that the earphones have been removed from a user&#39;s ears. In another suitable embodiment, control circuitry in the electronic device may adjust noise cancellation circuitry in the electronic device based on information from the ear presence sensor structures.

Claims:
What is claimed is: 
     
       1. Earphones, comprising:
 speakers; 
 noise cancellation circuitry; 
 ear presence sensor structures, wherein the ear presence sensor structures comprise light-based sensor structures having at least one light source that emits infrared light and at least one light detector that detects the infrared light emitted by the at least one light source; 
 control circuitry configured to gather information from the ear presence sensor structures indicating whether the speakers are present at the ears of a user and configured to adjust the noise cancellation circuitry in response to the information from the ear presence sensor structures; 
 housing structures in which the speakers are mounted, wherein at least one light-based sensor structure is mounted in the housing structures; and 
 a headband that connects the housing structures, wherein at least one light-based sensor structure is mounted in the headband, and wherein the control circuitry adjusts the noise cancellation circuitry in response to the information from the light-based sensor structures in the housing structures and the light-based sensor structures in the headband. 
 
     
     
       2. The earphones defined in  claim 1  further comprising a battery, wherein the control circuitry is configured to adjust the noise cancellation circuitry to reduce power consumption of the battery. 
     
     
       3. A method for operating a pair of earphones having noise cancellation circuitry and configured to play audio content for a user comprising:
 with control circuitry in the earphones, gathering information from ear presence sensor structures in the earphones on whether the earphones are present at the ears of the user; and 
 in response to the information from the ear presence sensor structures, adjusting the noise cancellation circuitry in the earphones, wherein the ear presence sensor structures comprise an accelerometer-based sensor that detects changes in acceleration, wherein gathering information from the ear presence sensor structures comprises gathering earphone movement information from the accelerometer-based sensor, and wherein adjusting the noise cancellation circuitry comprises deactivating the noise cancellation circuitry in response to the earphone movement information indicating that the earphones are in motion. 
 
     
     
       4. The method defined in  claim 3  wherein the information indicates that the earphones are not present at the ears of the user based on the detected motion of the earphones and wherein adjusting the noise cancellation circuitry comprises deactivating the noise cancellation circuitry in response to determining that the earphones are not present at the ears of the user. 
     
     
       5. The method defined in  claim 4  wherein the audio content is played through a pair of speakers, the method further comprising:
 adjusting the audio content that is played through the speakers in response to determining that the earphones are not in the ears of the user. 
 
     
     
       6. The method defined in  claim 5  wherein adjusting the audio content that is played through the speakers comprises pausing the audio content that is played through the pair of speakers. 
     
     
       7. The method defined in  claim 3  wherein the information indicates that the earphones are present at the ears of the user and wherein adjusting the noise cancellation circuitry comprises activating the noise cancellation circuitry in response to determining that the earphones are present at the ears of the user. 
     
     
       8. An electronic device operable to receive information from ear presence sensor structures in earphones coupled to the electronic device, comprising:
 noise cancellation circuitry; and 
 control circuitry configured to gather information from the ear presence sensor structures indicating whether speakers in the earphones are present at the ears of a user and configured to adjust the noise cancellation circuitry in response to the information from the ear presence sensor structures, wherein adjusting the noise cancellation circuitry comprises deactivating the noise cancellation circuitry while continuing to play audio content through the speakers. 
 
     
     
       9. The electronic device defined in  claim 8  wherein the ear presence sensor structures comprise an accelerometer-based sensor and wherein the control circuitry is configured to gather earphone movement information from the accelerometer-based sensor. 
     
     
       10. The electronic device defined in  claim 8  further comprising a battery, wherein the control circuitry is configured to adjust the noise cancellation circuitry to reduce power consumption of the battery. 
     
     
       11. The electronic device defined in  claim 8  wherein the control circuitry is configured to adjust audio playback to the earphones based on the information from the ear presence sensor structures. 
     
     
       12. The electronic device defined in  claim 8  wherein the control circuitry is configured to pause audio playback to the earphones based on information from the ear presence sensor structures indicating that the speakers in the earphones are not present at the ears of the user. 
     
     
       13. A method for operating an electronic device having noise cancellation circuitry and configured to play audio content for a user through a pair of earphones, comprising:
 with control circuitry in the electronic device, gathering information from ear presence sensor structures in the earphones on whether the earphones are present at the ears of the user of the electronic device; and 
 in response to the information from the ear presence sensor structures, adjusting the noise cancellation circuitry in the electronic device, wherein the ear presence sensor structures comprise an accelerometer-based sensor that detects changes in acceleration, wherein gathering information from the ear presence sensor structures comprises gathering earphone movement information from the accelerometer-based sensor, and wherein adjusting the noise cancellation circuitry comprises deactivating the noise cancellation circuitry in response to the earphone movement information indicating that the earphones are in motion. 
 
     
     
       14. The method defined in  claim 13  wherein the information indicates that the earphones are not present at the ears of the user based on the detected motion of the earphones and wherein adjusting the noise cancellation circuitry comprises deactivating the noise cancellation circuitry in response to determining that the earphones are not present at the ears of the user. 
     
     
       15. The method defined in  claim 14  further comprising:
 adjusting the audio content that is played through the earphones in response to determining that the earphones are not present at the ears of the user. 
 
     
     
       16. The method defined in  claim 15  wherein adjusting the audio content that is played through the earphones comprises pausing the audio content that is played through earphones. 
     
     
       17. The method defined in  claim 13  wherein the information indicates that the earphones are present at the ears of the user and wherein adjusting the noise cancellation circuitry comprises activating the noise cancellation circuitry in response to determining that the earphones are present at the ears of the user.

Description:
BACKGROUND 
     This relates to electronic devices and, more particularly, to electronic devices with accessories such as earphones. 
     Accessories such as earphones are often used with media players, cellular telephones, and other electronic devices. Some accessories have microphones that are used to form part of a noise cancellation circuit. When noise cancellation functions are active, the impact of ambient noise on audio playback can be reduced. Microphones can also be used to implement voice microphone noise cancellation. 
     There can be difficulties associated with noise cancelling earphones. For example, a user who is using earphones to listen to audio while noise cancellation circuitry in the earphones is active may occasionally need to remove the earphones. When doing so, the user may not be able to manually turn off noise cancellation features. Actively running noise cancellation operations in an accessory when a user is not using the accessory increases power consumption and decreases the battery life of the accessory. 
     It would therefore be desirable to be able to provide improved ways in which to control operation of an electronic device coupled to an accessory such as noise cancelling earphones. 
     SUMMARY 
     An electronic device may be coupled to an accessory such as a pair of earphones having noise cancellation features. The noise cancellation features may be used to reduce the impact of ambient noise on the audio content that is played through the earphones. 
     The earphones may have ear presence sensor structures that determine whether or not speakers in the earphones are present at the ears of the user. Information from the ear presence sensor structures may be used to control the operation of the noise cancellation features. In one suitable embodiment, noise cancellation features may be implemented using noise cancellation circuitry in the earphones. With this type of configuration, control circuitry in the earphones may adjust the noise cancellation circuitry in response to information from the ear presence sensor structures. For example, control circuitry in the earphones may automatically deactivate noise cancellation circuitry when information from the ear presence sensor structures indicates that the earphones have been removed from a user&#39;s ears. When information from the ear presence sensor structures indicates that the earphones have been placed in or on the user&#39;s ears, the control circuitry in the earphones may, if desired, automatically activate the noise cancellation circuitry. 
     In another suitable embodiment, noise cancellation features may be implemented using noise cancellation circuitry in the electronic device. With this type of configuration, information from ear presence sensor structures may be conveyed to control circuitry in the electronic device. The control circuitry may adjust the noise cancellation circuitry in response to information received from the ear presence sensor structures. For example, control circuitry in the electronic device may automatically deactivate noise cancellation circuitry when information from the ear presence sensor structures indicates that the earphones have been removed from a user&#39;s ears. When information from the ear presence sensor structures indicates that the earphones have been placed in or on the user&#39;s ears, the control circuitry in the earphones may, if desired, automatically activate the noise cancellation circuitry. 
     Controlling the operation of noise cancellation circuitry based on whether or not the earphones are present at the user&#39;s ears may reduce the power consumption of a battery in the earphones or in the electronic device. 
     The ear presence sensor structures may include switch-based sensors, accelerometer-based sensors, light-based sensors, or other suitable types of sensors. 
     Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front perspective view of an illustrative electronic device and associated accessory in accordance with an embodiment of the present invention. 
         FIG. 2  is a schematic diagram of an illustrative electronic device and associated accessory in accordance with an embodiment of the present invention. 
         FIG. 3  is a schematic diagram of an illustrative electronic device and associated accessory in which noise cancellation circuitry is located in the electronic device in accordance with an embodiment of the present invention. 
         FIG. 4  is a schematic diagram of an illustrative electronic device and associated accessory in which noise cancellation circuitry is located in the accessory in accordance with an embodiment of the present invention. 
         FIG. 5  is a perspective view of an illustrative speaker housing such as an earbud speaker housing that has ear presence sensor structures in accordance with an embodiment of the present invention. 
         FIG. 6  is a perspective view of an illustrative speaker housing such as an in-ear speaker housing that has ear presence sensor structures in accordance with an embodiment of the present invention. 
         FIG. 7  is a perspective view of illustrative earphones such as over-the-ear headphones that have ear presence sensor structures in accordance with an embodiment of the present invention. 
         FIG. 8  is a cross-sectional side view of an earphone housing of the type that may be provided with sensor structures for detecting the presence of an ear or other external object in accordance with an embodiment of the present invention. 
         FIG. 9  is a flow chart of illustrative steps involved in using an electronic device and accessory having noise cancellation features in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic device accessories such as earphones may be provided with noise cancellation features. When noise cancellation features are activated, the impact of ambient noise on audio content that is played through the earphones can be reduced. Noise cancellation features may also be used to perform voice microphone noise cancellation. 
     Noise cancellation features may be implemented using one or more noise cancellation microphones. For example, a voice microphone in the accessory may have an associated noise cancellation microphone that picks up ambient noise in the vicinity of the voice microphone. 
     Earphone speaker housings in an accessory may also have noise cancellation microphones. For example, each earphone speaker housing in a headset may have an external noise cancellation microphone on an outer surface of the earphone speaker housing. In addition to the external noise cancellation microphone or instead of the external noise cancellation microphone, each earphone speaker housing may have an internal noise cancellation microphone on an interior surface of the earphone speaker housing (e.g., adjacent to the ear). 
     In accessories with more speakers, more noise cancellation microphones may be used. For example, additional noise cancellation microphones can be provided in earbuds that contain multiple drivers or in surround sound accessories. A surround sound accessory might, for example, have five or six speakers (or more) and might have a noise cancellation microphone that is adjacent to each respective speaker. 
     Accessories such as earphones having noise cancellation features may be provided with the ability to sense the presence of external objects. For example, an earphone accessory may be provided with sensor structures such as ear presence sensor structures that can determine whether or not the earphones (i.e., the earphone speakers) are located in or on the ears of a user. 
     Information gathered by the sensor structures may be used to control the operation of noise cancellation features in the earphones. For example, control circuitry in the accessory or in the electronic device may automatically activate or deactivate noise cancellation features based on whether or not the earphones are located in or on the ears of a user. Controlling noise cancellation features in a pair of earphones coupled to an electronic device based on whether or not the user is wearing the earphones may reduce power consumption and extend the battery life of the earphones and/or of the electronic device. 
       FIG. 1  is a diagram of a system of the type that may be provided with an accessory having noise cancellation features for reducing the impact of ambient noise and sensing structures for detecting the presence of external objects such as the ears of a user. As shown in  FIG. 1 , system  8  may include electronic device  10  and accessory  20 . 
     Electronic device  10  may include a display such as display  14 . Display  14  may be a touch screen that incorporates a layer of conductive capacitive touch sensor electrodes or other touch sensor components or may be a display that is not touch-sensitive. Display  14  may include an array of display pixels formed from liquid crystal display (LCD) components, an array of electrophoretic display pixels, an array of plasma display pixels, an array of organic light-emitting diode display pixels, an array of electrowetting display pixels, or display pixels based on other display technologies. Configurations in which display  14  includes display layers that form liquid crystal display (LCD) pixels may sometimes be described herein as an example. This is, however, merely illustrative. Display  14  may include display pixels formed using any suitable type of display technology. 
     Display  14  may be protected using a display cover layer such as a layer of transparent glass or clear plastic. Openings may be formed in the display cover layer. For example, an opening may be formed in the display cover layer to accommodate a button such as button  16  and an opening such as opening  18  may be used to form a speaker port. 
     Device  10  may have a housing such as housing  12 . Housing  12 , which may sometimes be referred to as an enclosure or case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of any two or more of these materials. 
     Housing  12  may be formed using a unibody configuration in which some or all of housing  12  is machined or molded as a single structure or may be formed using multiple structures (e.g., an internal frame structure, one or more structures that form exterior housing surfaces, etc.). The periphery of housing  12  may, if desired, include walls. One or more openings may be formed in housing  12  to accommodate connector ports, buttons, and other components. For example, an opening may be formed in the wall of housing  12  to accommodate audio connector  24  and other connectors (e.g., digital data port connectors, etc.). Audio connector  24  may be a female audio connector (sometimes referred to as an audio jack) that has two pins (contacts), three pins, four pins, or more than four pins (as examples). Audio connector  24  may mate with male audio connector  22  (sometimes referred to as an audio plug) in accessory  20 . 
     Accessory  20  may be a pair of earphones (e.g., earbuds or earphones with other types of speakers), other audio equipment (e.g., an audio device with a single earbud unit), or other electronic equipment that communicates with electronic device  10 . The use of a pair of earphones in system  8  is sometimes described herein as an example. This is, however, merely illustrative. Accessory  10  may be implemented using any suitable electronic equipment. 
     It should be understood that the term “earphones” may refer to any suitable type of audio headset (e.g., headphones, over-the-ear headphones, earbuds, earbud-type headphones with ear hooks, in-ear headphones that extend partially into the ear canal, etc.). 
     As shown in  FIG. 1 , accessory  20  may include a communications path such as cable  26  that is coupled to audio plug  22 . Cable  26  may contain conductive lines (e.g., wires) that are coupled to respective contacts (pins) in audio connector  22 . The conductive lines of cable  26  may be used to route audio signals from device  10  to speakers in earphone units  28 . Earphone units  28  (which may sometimes be referred to as speakers or earphone housings) may include sensor structures for determining when earphone units  28  have been placed within the ears of a user. Microphone signals may be gathered using a microphone mounted in controller unit  30 . Controller unit  30  may also have buttons that receive user input from a user of system  8 . A user may, for example, manually control the playback of media by pressing button  30 A to play media or increase audio volume, by pressing button  30 B to pause or stop media playback, and by pressing button  30 C to reverse media playback or decrease audio volume (as examples). 
     The circuitry of controller  30  may communicate with the circuitry of device  10  using the wires or other conductive paths in cable  26  (e.g., using digital and/or analog communications signals). The paths in cable  26  may also be coupled to speaker drivers in earphones  28 , so that audio signals from device  10  may be played through the speakers in earbuds  28 . Electronic device  10  may regulate the volume of sound produced by earbuds  28  by controlling the audio signal strength used in driving the speakers in earbuds  28 . 
     In one suitable embodiment, sensor signals from sensor structures in earbuds  28  may be conveyed to device  10  using the conductive paths of cable  26 . With this type of configuration, electronic device  10  may process the sensor signals and take suitable action based on a determination of whether or not earphones  20  are located in or on a user&#39;s ears. 
     A schematic diagram showing illustrative components that may be used in device  10  and accessory  20  of system  8  is shown in  FIG. 2 . As shown in  FIG. 2 , electronic device  10  may include control circuitry  32  and input-output circuitry  34 . Control circuitry  32  may include storage and processing circuitry that is configured to execute software that controls the operation of device  10 . Control circuitry  32  may be implemented using one or more integrated circuits such as microprocessors, application specific integrated circuits, memory, and other storage and processing circuitry. Control circuitry  32  may, if desired, include noise cancellation circuitry and other audio processing circuitry  46 . 
     Input-output circuitry  34  may include components for receiving input from external equipment and for supplying output. For example, input-output circuitry  34  may include user interface components for providing a user of device  10  with output and for gathering input from a user. As shown in  FIG. 2 , input-output circuitry  34  may include communications circuitry  36 . Communications circuitry  36  may include wireless circuitry such as radio-frequency transceiver circuitry with a radio-frequency receiver and/or a radio-frequency transmitter. Radio-frequency transceiver circuitry in the wireless circuitry may be used to handle wireless signals in communications bands such as the 2.4 GHz and 5 GHz WiFi® bands, cellular telephone bands, and other wireless communications frequencies of interest. Communications circuitry  36  may also include wired communications circuitry such as circuitry for communicating with external equipment over serial and/or parallel digital data paths. 
     Input-output devices  38  may include buttons such as sliding switches, push buttons, menu buttons, buttons based on dome switches, keys on a keypad or keyboard, or other switch-based structures. Input-output devices  38  may also include status indicator lights, vibrators, display touch sensors, speakers, microphones, camera sensors, ambient light sensors, proximity sensors, and other input-output structures. 
     Electronic device  10  may be coupled to components in accessory  20  using cables such as cable  26  of accessory  20 . Accessory  20  may include speakers such as a pair of speaker drivers  40  (e.g., a left speaker and a right speaker). If desired, accessory  20  may include more than one driver per earbud. For example, each earbud in accessory  20  may have a tweeter, a midrange driver, and a bass driver (as an example). Speaker drivers  40  may be mounted in earbuds or other earphone housings. The use of left and right earbuds to house respective left and right speaker drivers  40  is sometimes described herein as an example. 
     Accessory  20  may include control circuitry such as control circuitry  45 . Control circuitry  45  may, for example, include storage and processing circuits formed from one or more integrated circuits or other circuitry. Circuitry  45  in accessory  20  may include noise cancellation circuitry and other audio processing circuitry  48 , if desired. 
     Cables such as cable  26  may form a communications path that can be used in conveying signals between device  10  and accessory  20 . The communications path may be used to transmit audio from circuitry  32  to speaker drivers  40  during playback operations. 
     The communications path may also be used to convey noise signals. Noise cancellation may, for example, be performed using the processing circuitry of device  10  (e.g., using noise cancellation circuitry  46 ). In this type of arrangement, noise signals gathered by one or more microphones in earphones  20  may be routed to circuitry  46 . Circuitry  46  may then route audio signals from which noise has been cancelled to headset  20 . If desired, noise cancellation operations may be performed locally in headset  20 . With this type of arrangement, noise cancellation circuitry  48  in headset  20  can receive audio playback signals from device  10  and can receive noise signals from noise cancellation microphones in earphones  20 . Circuitry  48  can then cancel noise from the played back audio. 
     If desired, accessory  20  may include user input devices  42  such as buttons (see, e.g., the buttons associated with button controller  30  of  FIG. 1 ), touch-based input devices (e.g., touch screens, touch pads, touch buttons), a microphone to gather voice input, other microphones such as noise cancellation microphones, and other user input devices. 
     To determine whether or not the earbuds in which speaker drivers  40  are located in or on the ears of a user, accessory  20  may be provided with ear presence sensor structures  44 . Ear presence sensor structures  44  may be configured to detect whether or not the speakers of earphones  20  are present at the ears of a user. Ear presence sensors may be formed from force sensors, from switches or other mechanical sensors, from capacitive sensors, from resistance-based sensors, from light-based sensors, from accelerometer-based sensors, and from acoustic-based sensors such as ultrasonic acoustic-based sensors (as examples). Control circuitry  45  in accessory  20  and/or control circuitry  32  of electronic device  10  may use information from ear presence sensor structures  44  in determining which actions should be automatically taken by device  10  and/or by accessory  20 . 
     A schematic diagram of device  10  and accessory  20  in a configuration in which noise cancellation circuitry is located in device  10  is shown in  FIG. 3 . As shown in  FIG. 3 , accessory  20  may include one or more microphones such as microphones  50 . Microphones  50  may include noise cancellation microphones that are used to gather ambient noise signals associated with speakers  40 . For example, a first microphone  50  may be configured to gather ambient noise signals associated with a left speaker driver  40 , while a second microphone  50  may be configured to gather ambient noise signals associated with a right speaker driver  40 . Using noise cancellation techniques, the ambient noise signals can be used to reduce noise in the audio being played through speakers  40 . 
     Noise cancellation techniques can also be implemented for microphones. For example, microphones  50  may include a voice microphone and a corresponding noise cancellation microphone. The voice microphone may be used to gather a user&#39;s voice signals during telephone calls or to record audio clips, while the corresponding noise cancellation microphone may be used to gather ambient noise signals associated with the voice microphone. Ambient noise signals gathered by the noise cancellation microphone may be used to reduce noise in the voice signals gathered by the voice microphone. 
     Noise cancellation operations may be performed using analog circuitry or using digital processing techniques. Noise cancellation operations may be performed locally in accessory  20  or may be performed remotely in device  10 . In the example of  FIG. 3 , noise cancellation operations are performed remotely in device  10 . 
     As shown in  FIG. 3 , device  10  may include audio processing circuitry  46 . Audio processing circuitry  46 , which is sometimes referred to as a codec or audio codec, may be used to generate audio signals, to receive and process audio signals, and to receive and process sensor signals from sensor structures  44 . Circuitry  46  may include analog-to-digital (A/D) converter circuitry  52  and digital-to-analog (D/A) converter circuitry  54 . Analog-to-digital converter circuitry  52  in device  10  may be used to digitize analog signals such as analog audio signals. For example, analog-to-digital converter circuitry  52  may be used to digitize one or more analog microphone signals such as analog microphone signals gathered by microphones  50 . Digital-to-analog converter circuitry  54  may be used to generate analog output signals. For example, digital-to-analog converter circuitry  54  may receive digital signals corresponding to the audio portion of a media playback event, audio for a telephone call, noise signals, an alert tone or signal (e.g., a beep or ring), or any other digital information. Based on this digital information, digital-to-analog converter circuitry  54  may produce corresponding analog signals (e.g., analog audio). 
     Audio processing circuitry  46  may be powered by a power source such as battery  47 . If desired, accessory  20  may also include a power source such as battery  57 . This is, however, merely illustrative. The use of a battery such as battery  57  in accessory  20  is optional and is only shown as an illustrative example. 
     Audio processing circuitry  46  may include a digital signal processor that may be used to perform digital signal processing on digitized audio signals. For example, if operating accessory  20  in a noise cancellation mode, noise signals from microphones  50 , which may reflect the amount of ambient noise in the vicinity of speaker drivers  40  and/or the amount of ambient noise in the vicinity of a voice microphone) may be conveyed to audio processing circuitry  46  in device  10 . Using the processing capabilities of an audio digital signal processor in circuitry  46 , the noise signals can be digitally removed from digital audio voice signals and from digital speakers signals. 
     This is, however, merely illustrative. If desired, circuitry  46  may perform noise cancellation operations using analog noise cancellation circuitry. With this type of configuration, noise signals gathered by microphones  50  may be conveyed to circuitry  46  in device  10 . Audio processing circuitry  46  may produce an anti-noise signal and may convey the anti-noise signal to speaker drivers  40  along with the audio signal that is to be heard by the user. The anti-noise signal may be identical to the noise signal except that it is shifted by 180 degrees with respect to the noise signal. The anti-noise signal may be superimposed onto the noise signal such that destructive interference occurs and the two signals mutually cancel. 
     Noise cancellation circuitry of the type shown in  FIG. 3  may be controlled manually by the user and/or may be controlled automatically based on sensor signals gathered by ear presence sensor structures  44 . For example, audio control circuitry  32  may automatically deactivate noise cancellation functions when information from sensor structures  44  indicates that earphones  20  have been removed from a user&#39;s ears and may automatically activate noise cancellation functions when information from sensor structures  44  indicates that earphones  20  have been placed in or on a user&#39;s ears. Because power is required to perform active noise cancellation operations, automatically controlling noise cancellation functions based on whether or not earphones  20  are in a user&#39;s ears may optimize the battery life of device  10 . 
     If desired, audio signal processing operations for implementing noise cancellation functions may be performed locally in accessory  20 . As shown in  FIG. 4 , accessory  20  may include audio signal processing circuitry  48 . Circuitry  48  may include analog-to-digital converter circuitry  56  (e.g., for digitizing analog audio signals from a microphone in accessory  20 ) and digital-to-analog converter circuitry  58  (e.g., to convert digital signals to analog signals that are played back through the speakers of accessory  20 ). If desired, audio processing circuitry  48  may receive power from a power supply such as battery  57  or may be powered using other methods (e.g., device  10  may provide power to accessory  20  via cable  26  of  FIG. 1 ). The use of a battery such as battery  57  in accessory  20  is merely illustrative. 
     Circuitry  48  may be used to locally implement noise cancellation functions. In a typical local noise cancellation arrangement using digital processing techniques, analog microphone signals (noise signals) from microphones  50  are digitized using analog-to-digital circuitry  56 . Processing circuitry  48  may receive audio signals (e.g., played back music) from device  10  in digital form. Audio processing circuitry  48  may then use digital processing techniques to remove noise from the played back audio. The resulting audio signal may be converted to analog for speakers  40  using digital-to-analog converter circuitry  58 . 
     This is, however, merely illustrative. If desired, circuitry  48  may perform noise cancellation operations using analog noise cancellation circuitry. With this type of configuration, noise signals gathered by microphones  50  may be conveyed to circuitry  48  in accessory  20 . Audio processing circuitry  48  may produce an anti-noise signal and may convey the anti-noise signal to speaker drivers  40 . The anti-noise signal may be identical to the noise signal except that it is shifted by 180 degrees with respect to the noise signal. The anti-noise signal may be superimposed onto the noise signal such that destructive interference occurs and the two signals mutually cancel. 
     Noise cancellation circuitry of the type shown in  FIG. 4  may be controlled manually by the user and/or may be controlled automatically based on sensor signals gathered by ear presence sensor structures  44 . For example, control circuitry  45  may automatically deactivate noise cancellation functions when information from sensor structures  44  indicates that earphones  20  have been removed from a user&#39;s ears and may automatically activate noise cancellation functions when information from sensor structures  44  indicates that earphones  20  have been placed in or on a user&#39;s ears. Because power is required to perform active noise cancellation operations, automatically controlling noise cancellation functions based on whether or not earphones  20  are in a user&#39;s ears may optimize the battery life of earphones  20 . 
     An illustrative earbud speaker housing with an ear presence sensor is shown in  FIG. 5 . In the example of  FIG. 5 , earbud  28  has a housing such as housing  66  in which one or more speaker drivers such as speakers  40  of  FIG. 2  are mounted. 
     Conductive structures such as conductive mesh structures  68  and  70  may be mounted in housing  66 . As shown in  FIG. 5 , for example, mesh structures  68  and  70  may be mounted in the front of housing  66  so that sound from the speakers inside earbud housing  66  may pass through the holes of the mesh. If desired, earbud  28  may contain microphone structures (e.g., when implementing noise cancellation features in earbud  28 ). The use of mesh when forming electrode structures  68  and  70  may allow ambient sound to be picked up by the noise cancellation microphones in housing  66 . 
     Mesh electrodes  68  and  70  (e.g., metal screen structures) or other conductive structures in earbud  28  may be used as first and second terminals in a resistive (resistance-based) sensor. Control circuitry in housing  66  may be used to apply a voltage across the first and second terminals while measuring how much current flows as a result. The control circuitry may use information on the voltage and current signals that are established between electrodes  68  and  70  to determine whether or not earbud  28  has been placed in the ear of a user. In the absence of the user&#39;s ear, the resistance between electrodes  68  and  70  will be relatively high. When, however, earbud  28  has been placed into a user&#39;s ear, contact between electrodes  68  and  70  and the flesh of the ear will give rise to a lower resistance path between electrodes  68  and  70 . 
     To determine whether or not earbud  28  has been placed within the user&#39;s ear, control circuitry  45  of earbud (and/or control circuitry  32  of  FIG. 2 ) may measure the resistance between electrodes  68  and  70  and may compare the measured resistance to a predetermined threshold. When the measured resistance is below the predetermined threshold, circuitry  45  can conclude that earbud  28  has been placed in the ear of the user and may, if desired, automatically activate noise cancellation circuitry. When the measured resistance exceeds the predetermined threshold, circuitry  45  can conclude that earbud  28  is out of the ear and may, if desired, automatically deactivate noise cancellation circuitry. 
     In configurations where noise cancellation functions are performed remotely in device  10 , control circuitry  32  in device  10  may analyze sensor signals from ear presence sensors in earphones  20  and may automatically activate and deactivate noise cancellation circuitry in device  10  based on the sensor signals. Configurations in which noise cancellation is performed and controlled locally in earphones  20  and in which sensor signals from ear presence sensors are analyzed by control circuitry  45  in earphones  20  are sometimes described herein as an example. 
     In addition to or instead of using mesh  68  and  70  to measure the resistance of the user&#39;s ear, mesh electrodes  68  and  70  may be used as capacitive sensor electrodes (e.g., to make mutual capacitance measurements or to make self capacitance measurements). Different capacitance values may be detected in the presence and absence of the user&#39;s ear in the vicinity of electrodes  68  and  70 . This allows circuitry  45  to use the capacitance measurements to determine whether or not earbud  28  is in, on, or out of the user&#39;s ear. 
     If desired, earbud  28  may include a sealing member such as compressible sealing member  72 . Sealing member  72  may be used to form a seal between a user&#39;s ear and earbud  28  that helps block ambient noise while also forming an enclosed cavity adjacent to the ear canal. In addition to or instead of using mesh  68  and  70  to detect the presence of a user&#39;s ear, an ear presence sensor such as ear presence sensor  74  may be embedded in or formed on sealing member  72 . 
     As an example, ear presence sensor  74  may be a switch-based sensor such as a switch or button that is actuated when a user&#39;s ear is present or absent. Switch  74  may be mounted on an exterior surface of earbud housing  66  or may be embedded or formed on sealing member  72 . Switch  74  may be configured to move inwards (e.g., towards the interior of housing  66 ) and to move outwards (e.g., towards the exterior of housing  66 ). When earbud  28  is inserted into a user&#39;s ear, switch  74  may be compressed inward. When earbud  28  is out of the user&#39;s ear, switch  74  may move outwards to regain its original uncompressed state. Circuitry  45  may use information from switch structures such as switch structure  74  to determine whether or not earbud  28  has been placed in a user&#39;s ear. If desired, a switch-based ear presence sensor of this type may be implemented without requiring electrical power. 
     As additional examples, sensor structure  74  may be an accelerometer-based sensor, an orientation sensor, or other sensor that may be used in gathering earphone movement information and/or determining the location or orientation of earbud  28 . Changes in orientation and/or changes in acceleration may be used to determine whether or not earphones  20  are in or on a user&#39;s ears. For example, when movement is detected by sensor  74 , circuitry  45  can conclude that earphones  20  are not in the user&#39;s ears. When movement is not detected by sensor  74  for a predetermined period of time, circuitry  45  can conclude that earphones  20  are not in the user&#39;s ears. 
     If desired, ear presence sensor  74  may be a pressure or force sensor configured to measure a pressure or force against sealing member  72 . In force-based sensor schemes, the resistance of a compressible foam may be measured or a strain gauge output can be monitored. When force is present, circuitry  45  can conclude that earphones  20  have been inserted into or mounted on a user&#39;s ears, whereas when force is not present, circuitry  45  can conclude that earphones  20  are not being worn by the user. Force indicative of a user&#39;s ear pressing against earphones  20  may also be monitored using piezo-electric force sensors or other force sensors. 
     These examples are, however, merely illustrative. In general, any suitable type of sensor may be used to detect the presence and/or absence of a user&#39;s ear in the vicinity of earbud  28 . 
       FIG. 6  is a perspective view of an illustrative in-ear speaker housing with an ear presence sensor. In the example of  FIG. 6 , in-ear earbud  28  includes sealing members  76  configured to extend partially into the ear canal of a user&#39;s ear. Earphones of the type shown in  FIG. 6  are sometimes referred to as ear-canal headphones. 
     As shown in  FIG. 6 , ear presence sensor  74  may be embedded in or formed on one of sealing members  76 . Ear presence sensor  74  may be an accelerometer-based sensor, a pressure or force sensor, a capacitive sensor, a switch-based sensor (e.g., sensor  74  may be a mechanical switch that is actuated when earbud  28  is inserted or removed from a user&#39;s ear), or any other suitable type of sensor configured to detect the presence and/or absence of a user&#39;s ear in the vicinity of earbud  28 . 
       FIG. 7  is a perspective view of illustrative over-the-ear headphones having one or more ear presence sensor structures. In the example of  FIG. 7 , accessory  20  includes a headband such as headband  78  with left and right over-the-ear speaker housings  28 . A sealing member such as sealing member  80  may be a ring or layer of foam or may be any other suitable type of ear pad configured to form a seal around the user&#39;s ear to help block out ambient noise. 
     As shown in  FIG. 7 , accessory  20  may include one or more user detection sensors such as ear presence sensor structures  82  and  84 . Ear presence sensor structures  84  may be embedded in or formed on sealing members  80  and may be configured to detect the presence and absence of a user&#39;s ears in the vicinity of speaker housings  28 . Ear presence sensor  82  may be embedded in or formed on headband portion  78  and may be configured to detect the presence and absence of a user&#39;s head adjacent to headband  78 . When information from sensor  82  indicates that a user&#39;s head is not present, device  10  can conclude that the user is not wearing headphones  20 . When information from sensor  82  indicates that a user&#39;s head is present, device  10  can conclude that the user is wearing headphones  20 . 
     Ear presence sensor structures  82  and  84  may be accelerometer-based sensors, pressure or force sensors, capacitive sensors, acoustic-based sensors, switch-based sensors (e.g., sensors formed form mechanical switches that are actuated when a user&#39;s ear or head is present or absent), or any other suitable type of sensor configured to detect the presence and/or absence of a user&#39;s ear or head. 
     A cross-sectional side view of an illustrative earbud with a speaker driver and an associated ear presence sensor is shown in  FIG. 8 . As shown in  FIG. 8 , earbud  28  may have a housing such as housing  66 . Speaker  40  may be mounted within housing  66  overlapping an acoustic grill formed from structures such as mesh  68  and  70  or other acoustic mesh. During operation, sound  88  may pass through the acoustic mesh. For example, speaker  40  may produce sound that is received by a user&#39;s ear or other external object  80 . 
     When external object  80  is sufficiently close to earbud  28 , the presence of external object  80  may be detected. For example, control circuitry  45  may measure the resistance between mesh electrodes  68  and  70  using conductive paths  82  or may use capacitance measurements in monitoring for the presence of object  80 . The measured resistance (or capacitance) may then be used to determine whether earbud  28  is in the user&#39;s ear or is out of the user&#39;s ear. Control circuitry  45  may also use sensors such as sensor  44  of  FIG. 8  to monitor for the presence or absence of external objects such as the user&#39;s ear. As shown in  FIG. 8 , sensor  44  may have a transmitter such as transmitter  44 T and may have a receiver such as receiver  44 R. During operation of sensor  44 , sensor  44  may transmit signals such as signal  84  and may gather reflected signals such as signal  86 . The strength of received signal  86  may be used to measure whether or not external object  80  is in the presence of earbud  28 . 
     Sensor  44  may be a light-based sensor. For example, transmitter  44 T may be a light-emitting diode or laser that emits light  84  (e.g., infrared light, visible light, etc.) and receiver  44 R may be a light detector (e.g., a photodiode or phototransistor) that measures the amount of light  84  that is reflected as reflected light  86  from external object  80 . When the amount of light that is reflected from external object  80  is high, circuitry  45  can conclude that earbud  28  is in the user&#39;s ear. When the amount of light that is reflected from external object  80  is low, circuitry  45  can conclude that earbud  28  is out of the user&#39;s ear. 
     If desired, sensor  44  may be a sensor that emits and receives acoustic signals. For example, transmitter  44 T may be an ultrasonic signal transducer that transmits ultrasonic signals  84 . Receiver  44 R may be an ultrasonic signal receiver that measures the amount of corresponding ultrasonic signal  84  that is reflected as reflected signal  86  from external object  80 . When the amount of ultrasonic signal that is reflected from external object  80  is low, circuitry  45  can conclude that earbud  28  is not in the user&#39;s ear. When the amount of ultrasonic signal that is reflected from external object  80  is high, circuitry  45  can conclude that earbud  28  is currently in the user&#39;s ear. 
     In configurations where noise cancellation operations are performed locally in accessory  20 , circuitry  45  in accessory  20  may use information from sensor structures  44  to control noise cancellation circuitry  48 . For example, when information from sensor structures  44  indicates that earphones  20  have been removed from a user&#39;s ears, control circuitry  45  may automatically deactivate noise cancellation circuitry  48 . When information from sensor structures  44  indicates that earphones  20  have been placed in or on a user&#39;s ears, control circuitry  45  may automatically deactivate noise cancellation circuitry  48 , thereby conserving the battery life of earphones  20 . 
     In configurations where noise cancellation operations are performed remotely in device  10 , circuitry  32  ( FIG. 2 ) in accessory  20  may receive information from sensor structures  44  via cable  26 . Circuitry  32  may control noise cancellation functions based on the information from sensor structures  44 . For example, when information from sensor structures  44  indicates that earphones  20  have been removed from a user&#39;s ears, control circuitry  32  may automatically deactivate noise cancellation circuitry  46 . When information from sensor structures  44  indicates that earphones  20  have been placed in or on a user&#39;s ears, control circuitry  32  may automatically activate noise cancellation circuitry  46 , thereby conserving the battery life of device  10 . 
     A flow chart of illustrative steps involved in using system  8  is shown in  FIG. 9 . During the operations of step  100 , earphones  20  may be located in or on the ears of a user and may be operated normally while using sensor circuitry  44  to monitor for the presence or absence of speaker housings  28  of accessory  20  in or on the ears of a user. In configurations where earphones  20  are over-the-ear headphones ( FIG. 7 ), sensor circuitry  44  may be used to monitor the presence or absence of the user&#39;s head near headband  78  or the presence or absence of the user&#39;s ears near over-the-ear speaker housings  28 . Circuitry  45  (and/or circuitry  32 , if desired) may be used in evaluating sensor data and taking appropriate action. Configurations in which control circuitry  45  is used in taking action based on sensor data are sometimes described herein as an example. 
     Examples of operations that may be performed by system  8  during step  92  include audio-based operations such as playing media content (e.g., media content stored on device  10  or media content provided by an online service), providing a user with audio associated with a telephone call, providing audio associated with a video chat session to the user, or otherwise presenting audio content through earphones  20 . Audio may be played in stereo so that left and right earbuds receive corresponding left and right channels of audio, may be played using a multi-channel surround sound scheme, or may be played using a monophonic (mono) sound scheme in which both the left and right channels of audio are identical. During the audio-based operations of step  92 , noise cancellation circuitry  48  (or noise cancellation circuitry  46  in device  10 ) may be active to reduce the impact of ambient noise on the audio content played through earphones  20 . Configurations where noise cancellation circuitry  48  in earphones  20  is used to perform noise cancellation operations is sometimes described herein as an example. It should be understood, however, that the steps of  FIG. 9  may also be performed in configurations where noise cancellation circuitry (e.g., noise cancellation circuitry  46 ) is located in device  10 . 
     During the monitoring operation of step  100 , circuitry  45  can use user detection sensors  44  to determine whether or not earphones  20  are in or on the user&#39;s ears. 
     If, during the operations of step  100 , it is determined that earphones  20  have been removed from the user&#39;s ears, circuitry  45  may take suitable action at step  102 . For example, circuitry  45  may deactivate noise cancellation circuitry  48  in response to information from sensor structures  44  indicating that earphones  20  have been removed from the user&#39;s ears. If desired, circuitry  32  in device  10  may adjust the audio content being played based on the information gathered by sensor structures  44 . For example, circuitry  32  may pause or stop the audio content being played, may adjust the playback volume (audio signal drive strength), may switch from a stereo playback scheme to a monophonic playback scheme, or may take other suitable actions based on information from sensor structures  44 . 
     After taking suitable actions at step  102 , device  10  can be operated in an earphones-off mode (step  104 ). For example, earphones  20  may operate with noise cancellation circuitry deactivated (i.e., turned off). This may include continuing to play audio content without performing noise cancellation operations, operating with paused or stopped audio playback, etc. 
     During the operations of step  104 , ear presence sensor structures  44  may be used to monitor for the presence of earphones  20  in or on the ears of the user. 
     If, during the operations of step  104 , sensor structures  44  determine that earphones  20  have been placed in or on the user&#39;s ears, appropriate action may be taken at step  106 . Suitable actions that may be taken by system  8  in response to earphones  20  being placed in or on the user&#39;s ears include activating noise cancellation circuitry  48 , resuming media playback, and/or restoring a previous volume level of the media playback (as examples). Operations may then proceed to step  100 , where system  8  may operate in an earphones-on mode while circuitry  45  monitors sensor structures  44  to determine when earphones  20  are removed from the user&#39;s ears. 
     The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20121129
Publication Date: 20160517
Grant Date: 20160517
Priority Date: 20121129
Inventors: RUNDLE NICHOLAS A.
Assignee: APPLE INC
CPC Classifications: [{"code": "H04R2460/01", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/1083", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R2460/01", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/1083", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R1/1083", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R2460/01", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/1041", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 50773330