PATENT DOCUMENT

Publication Number: US-10063964-B2
Application Number: US-201715446793-A
Country: US
Kind Code: B2

Title: Electronic device with wireless power control system

Abstract:
An electronic device may include wireless circuitry that is configured to transmit wireless signals during operation. A maximum transmit power level may be established that serves as a cap on how much power is transmitted from the electronic device. Adjustments may be made to the maximum transmit power level in real time based on sensor signals and other information on the operating state of the electronic device. The sensor signals may include motion signals from an accelerometer. The sensor signals may also include ultrasonic sound detected by a microphone. Device orientation data may be used by the device to select whether to measure the ultrasonic sound using a front facing or rear facing microphone. Maximum transmit power level may also be adjusted based on whether or not sound is playing through an ear speaker in the device.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 an accelerometer; 
 an ear speaker; 
 a radio-frequency antenna with which radio-frequency signals are transmitted with a transmit power that is capped at a maximum transmit power level; and 
 circuitry that is configured to adjust the maximum transmit power level based at least partly on data from the accelerometer and at least partly in response to determining that no audio is being played through the ear speaker. 
 
     
     
       2. The electronic device defined in  claim 1  wherein the circuitry is configured to gather motion information using the accelerometer that is associated with motion of the electronic device. 
     
     
       3. The electronic device defined in  claim 2  wherein the circuitry is configured to compare the gathered motion information to a predetermined motion threshold. 
     
     
       4. The electronic device defined in  claim 3  wherein the circuitry is configured to raise the maximum transmit power level in response to determining that the gathered motion information is less than the predetermined motion threshold. 
     
     
       5. The electronic device defined in  claim 1 , further comprising:
 a sound source that emits audio signals; and 
 a microphone, wherein the circuitry is configured to measure the emitted audio signals using the microphone. 
 
     
     
       6. The electronic device defined in  claim 5  wherein the circuitry is configured to compare the measured emitted audio signals to a predetermined audio signal threshold. 
     
     
       7. The electronic device defined in  claim 6  wherein the circuitry is configured to raise the maximum transmit power level in response to determining that the measured emitted audio signals are greater than the predetermined audio signal threshold. 
     
     
       8. The electronic device defined in  claim 5 , further comprising:
 a housing having opposing first and second ends, wherein the sound source is formed at the first end and the microphone is formed at the second end. 
 
     
     
       9. The electronic device defined in  claim 8  wherein the microphone comprises a first microphone and the housing has opposing front and rear surfaces, the electronic device further comprising:
 a second microphone, wherein the first microphone is formed at the front surface and the second microphone is formed at the rear surface. 
 
     
     
       10. An electronic device configured to perform wireless communications while located on a surface of an external object, the electronic device comprising:
 a sound source that is configured to emit ultrasonic sound towards the surface; 
 a microphone that is configured to measure a portion of the emitted ultrasonic sound that is transmitted along the surface and to generate a sound level corresponding to the measured portion of the emitted ultrasonic sound; 
 a radio-frequency antenna with which radio-frequency signals are transmitted with a transmit power that is capped at a maximum transmit power level; and 
 circuitry that is configured to adjust the maximum transmit power level based at least partly on the sound level that is generated by the microphone. 
 
     
     
       11. The electronic device defined in  claim 10 , wherein the circuitry is configured to compare the sound level corresponding to the measured ultrasonic sound to a predetermined threshold. 
     
     
       12. The electronic device defined in  claim 11 , wherein the circuitry is configured to set the maximum transmit power level to a first level in response to determining that the sound level is greater than the predetermined threshold, the circuitry is configured to set the maximum transmit power level to a second level in response to determining that the sound level is less than the predetermined threshold, and the first level is different than the second level. 
     
     
       13. The electronic device defined in  claim 12 , wherein the first level is greater than the second level. 
     
     
       14. The electronic device defined in  claim 10 , further comprising:
 a housing having opposing first and second ends, wherein the microphone is formed at the first end and the sound source is formed at the second end. 
 
     
     
       15. A method of adjusting a maximum wireless signal transmit power level in a portable electronic device that includes sensor circuitry and processing circuitry, the method comprising:
 with the sensor circuitry, gathering sensor data; 
 with the processing circuitry, determining whether the portable electronic device is being held against a head of a user of the portable electronic device; 
 with the processing circuitry, determining whether the portable electronic device is resting on a body of the user based at least on the gathered sensor data; 
 with the processing circuitry, determining whether the portable electronic device is resting on a surface based at least on the gathered sensor data; and 
 with the processing circuitry, setting the maximum wireless signal transmit power level to a first level in response to determining that the portable electronic device is being held against the head of the user, setting the maximum wireless signal transmit power level to a second level that is different from the first level in response to determining that the portable electronic device is resting on the body of the user and not held against the head of the user, and setting the maximum wireless signal transmit power level to a third level that is different from the first and second levels in response to determining that the portable electronic device is resting on the surface, not held against the head of the user, and not resting on the body of the user. 
 
     
     
       16. The method defined in  claim 15 , wherein the portable electronic device further comprises an ear speaker and determining whether the portable electronic device is being held against the head of the user comprises determining whether sound is being played through the ear speaker. 
     
     
       17. The method defined in  claim 15 , wherein the sensor circuitry comprises an accelerometer that is configured to measure motion signals and a microphone that is configured to measure audio signals. 
     
     
       18. The method defined in  claim 15 , wherein determining whether the portable electronic device is resting on the body of the user based at least on the gathered sensor data comprises:
 comparing the measured motion signals to a motion threshold; and 
 comparing the measured audio signals to an audio threshold. 
 
     
     
       19. The method defined in  claim 15 , wherein the third level is greater than the first level and the second level and the first level is greater than the second level.

Description:
This application is a continuation of U.S. patent application Ser. No. 13/886,157, filed May 2, 2013, which is hereby incorporated by reference herein in its entirety. This application claims the benefit of and claims priority to U.S. patent application Ser. No. 13/886,157, filed May 2, 2013. 
    
    
     BACKGROUND 
     This relates generally to electronic devices, and more particularly, to electronic devices with wireless communications circuitry. 
     Electronic devices such as portable computers and handheld electronic devices are often provided with wireless communications capabilities. For example, electronic devices may have wireless communications circuitry to communicate using cellular telephone bands and to support communications with satellite navigation systems and wireless local area networks. 
     To satisfy consumer demand for small form factor wireless devices, manufacturers are continually striving to reduce the size of components that are used in these devices while providing enhanced functionality. It is generally impractical to completely shield a user of a compact handheld device from transmitted radio-frequency signals. For example, conventional cellular telephone handsets generally emit signals in the vicinity of a user&#39;s head during telephone calls. Government regulations limit radio-frequency signal powers. In particular, so-called specific absorption rate (SAR) standards are in place that impose maximum energy absorption limits on handset manufacturers. At the same time, wireless carriers require that the handsets that are used in their networks be capable of producing certain minimum radio-frequency powers so as to ensure satisfactory operation of the handsets. 
     The manufacturers of electronic devices such as portable wireless devices therefore face challenges in producing devices with adequate radio-frequency signal strengths that are compliant with applicable government regulations. 
     It would be desirable to be able to address these challenges by providing improved wireless communications circuitry for wireless electronic devices. 
     SUMMARY 
     An electronic device may include wireless circuitry that is configured to transmit wireless signals during operation. A maximum transmit power level may be established that serves as a cap on how much power is transmitted from the electronic device. Adjustments may be made to the maximum transmit power level in real time based on sensor signals and other information on the operating state of the electronic device. When it is determined that the electronic device is being operated while resting on an inanimate object such as a table, the maximum transmit power level may be set to a maximum value. When it is determined that the electronic device is resting on the body of a user, the maximum transmit power may be set to a reduced level. When it is determined that the electronic device is being held near the ear of a user so that the device is offset from the user&#39;s body, the maximum transmit power level may be set to a level between the reduced level and the maximum value. 
     The sensor signals that are gathered by the electronic device to ascertain how the electronic device is being used may include motion signals from an accelerometer. 
     The sensor signals may also include ultrasonic sound detected by a microphone. Device orientation data may be used by the device to select whether to measure the ultrasonic sound using a front facing or rear facing microphone. The maximum transmit power level may also be adjusted based on whether or not sound is playing through an ear speaker in the device. 
     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. 1A  is a front perspective view of an illustrative electronic device with wireless communications circuitry in accordance with an embodiment of the present invention. 
         FIG. 1B  is a rear perspective view of an illustrative electronic device with wireless communications circuitry in accordance with an embodiment of the present invention. 
         FIG. 2  is a schematic diagram of an illustrative electronic device with wireless communications circuitry in accordance with an embodiment of the present invention. 
         FIG. 3  is a diagram of an illustrative electronic device being used at the ear of a user in accordance with an embodiment of the present invention. 
         FIG. 4  is a diagram of an illustrative electronic device being used while resting on an inanimate object such as a table in accordance with an embodiment of the present invention. 
         FIG. 5  is a diagram of an illustrative electronic device being used while resting on a user body part such as the leg of a user in accordance with an embodiment of the present invention. 
         FIG. 6  is a schematic diagram of an illustrative electronic device configured to make dynamic adjustments to a maximum wireless transmit power level in accordance with an embodiment of the present invention. 
         FIG. 7  is a graph showing how use of an electronic device that is being held by a user or that is resting on the body of a user can be detected using an accelerometer that monitors device motion in accordance with an embodiment of the present invention. 
         FIG. 8  is a cross-sectional side view of an illustrative electronic device being used while resting on an external structure such as a body part or while resting on an inanimate object in accordance with an embodiment of the present invention. 
         FIG. 9  is a graph showing how ultrasonic audio signals can be detected by microphones on opposing sides of an electronic device while the device is resting on a surface such as a leg or other body part in accordance with an embodiment of the present invention. 
         FIG. 10  is a graph showing how ultrasonic audio signals can be detected by microphones on opposing sides of an electronic device while the device is resting on a surface of an inanimate object such as a table in accordance with an embodiment of the present invention. 
         FIG. 11  is a flow chart of illustrative steps involved in operating an electronic device while regulating a maximum transmitted wireless power level in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices such as electronic device  10  of  FIGS. 1A and 1B  may be provided with wireless communications circuitry. Information from sensor circuitry and other information may be used in controlling the operation of the wireless communications circuitry. For example, the maximum power level of transmitted wireless signals may be controlled in real time to ensure that regulatory limits are satisfied or are exceeded. 
     Electronic device  10  may be a portable electronic device or other suitable electronic device. For example, electronic device  10  may be a laptop computer, a tablet computer, a somewhat smaller device such as a wrist-watch device, pendant device, headphone device, earpiece device, or other wearable or miniature device, a cellular telephone, or a media player. Device  10  may also be a television, a set-top box, a desktop computer, a computer monitor into which a computer has been integrated, a wireless router, or other suitable electronic equipment. 
     Device  10  may include a housing such as housing  12 . Housing  12 , which may sometimes be referred to as a case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of these materials. In some situations, parts of housing  12  may be formed from dielectric or other low-conductivity material. In other situations, housing  12  or at least some of the structures that make up housing  12  may be formed from metal elements. 
     Device  10  may, if desired, have a display such as display  14 . Display  14  may, for example, be a touch screen that incorporates capacitive touch electrodes. Display  14  may include image pixels formed from light-emitting diodes (LEDs), organic LEDs (OLEDs), plasma cells, electrowetting pixels, electrophoretic pixels, liquid crystal display (LCD) components, or other suitable image pixel structures. A display cover layer such as a layer of clear glass or plastic may cover the surface of display  14 . Buttons such as button  13  may pass through openings in the cover layer. 
     The cover layer for display  14  may also have other openings such as an opening for speaker port  16 . Speaker port  16  may include a speaker such as speaker  18  and microphone  20 . Microphone  20  may be used to detect sound in the vicinity of speaker  18 . Microphone  20  may, for example, be used to detect ambient noise so that an ambient noise reduction feature can be implemented for speaker  18 . 
     Device  10  may have an elongated shape with a main longitudinal axis such as axis  26 . Speaker port  16 , which may sometimes be referred to as an ear speaker port or receiver port, may be located at upper end  21  of device  10  on the front face of device  10  (i.e., on the same side of device  10  that includes display  14 ). 
     Openings such as openings  22 ,  15 , and  24  may be located at opposing lower end  19  of device  10 . Openings such as opening  15  in device housing  12  may be associated with data ports. Openings such as openings  22  and  24  may be associated respectively with microphone and speaker ports. 
     Components such as front-facing camera  27 , ambient light sensor  29 , and infrared-light-based proximity sensor  31  may be formed in upper region  21  of device  10  or elsewhere on the front face of device  10  (as an example). 
     A rear perspective view of device  10  of  FIG. 1A  is shown in  FIG. 1B . As shown in  FIG. 1B , device  10  having surface  25  may include buttons such as buttons  23 . Buttons  23  may include volume buttons (e.g., volume up and volume down buttons) and buttons for placing device  10  in a ringer mode or silent mode (as examples). Device  10  may also include a rear-facing camera such as camera  33 , a camera flash such as flash  37 , and a rear-facing microphone such as microphone  35 . Microphone  35  may be used to gather data from a subject when a video clip of the subject is being recorded using camera  33 . 
     During operation of device  10 , a user of device  10  may hold device  10  against the user&#39;s head. For example, ear speaker  18  may be placed at the user&#39;s ear while microphone port  22  is placed in the vicinity of the user&#39;s mouth. This position for device  10  allows the user to have a telephone conversation. 
     Device  10  may also be operated wirelessly when not being held against the user&#39;s head. For example, device  10  may be used to browse the internet, to handle email and text messages, and to support other wireless communications operations. When not held against the user&#39;s head, device  10  may be used in a speakerphone mode in which microphone  22  is used to gather voice information from a user while speaker  24  is used to play back telephone call audio to the user. Speaker  24  may also be used to play back wirelessly streaming audio such as music to a user when device  10  is not being held against the user&#39;s head. 
     To ensure that regulatory limits on transmitted power are satisfied, it may be desirable to limit the maximum wireless transmit power level for device  10  whenever it can be determined that device  10  is in the vicinity of a user&#39;s body. For example, it may be desirable to limit the maximum wireless transmit power level for device  10  whenever it is determined that device  10  is being held against the user&#39;s head or when device  10  is being rested against another body part such as the user&#39;s leg. 
     Device  10  can make real time adjustments to the amount of wireless transmit power that is being used based on feedback from the wireless equipment with which device  10  is communicating and/or based on locally measured data. At the same time, the maximum wireless transmit power level can serve as a cap to ensure that the transmitted power does not exceed an acceptable level for the device&#39;s current environment, even if a higher transmit power is being requested by external equipment. By adjusting the maximum permitted transmit power dynamically, device  10  can be operated optimally in a variety of situations. 
     The user may sometimes rest device  10  on an external surface such as a table top or other inanimate object. In this type of situation, it may not be desirable to limit maximum wireless transmit power (i.e., it may be desirable to set the maximum transmit power level to a maximum value). Device  10  in this situation will not be adjacent to a user&#39;s body, so excessive limitations on wireless transmit power may be avoided to avoid needlessly degrading wireless performance. 
     To ensure that regulatory limits for emitted radiation are satisfied or exceeded, device  10  can monitor its operating state and can gather and analyze information from sensors. Different transmitted power limits may be imposed on transmitted wireless signals depending on the mode of operation of device  10 . 
     A schematic diagram of an illustrative configuration that may be used for electronic device  10  is shown in  FIG. 2 . As shown in  FIG. 2 , electronic device  10  may include control circuitry such as storage and processing circuitry  28 . Storage and processing circuitry  28  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 storage and processing circuitry  28  may be used to control the operation of device  10 . The processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio codec chips, application specific integrated circuits, etc. 
     Storage and processing circuitry  28  may be used to run software on device  10 , such as internet browsing applications, voice-over-internet-protocol (VOIP) telephone call applications, email applications, media playback applications, operating system functions, etc. To support interactions with external equipment, storage and processing circuitry  28  may be used in implementing communications protocols. Communications protocols that may be implemented using storage and processing circuitry  28  include internet protocols, wireless local area network protocols (e.g., IEEE 802.11 protocols—sometimes referred to as WiFi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol, cellular telephone protocols, etc. 
     Circuitry  28  may be configured to implement control algorithms that control the use of antennas and other wireless circuitry in device  10 . For example, circuitry  28  may perform signal quality monitoring operations, sensor monitoring operations, and other data gathering operations and may, in response to the gathered data and information on which communications bands are to be used in device  10 , control which antenna structures within device  10  are being used to receive and process data and/or may adjust one or more switches, tunable elements, or other adjustable circuits in device  10  to adjust antenna performance. As an example, circuitry  28  may control which of two or more antennas is being used to receive incoming radio-frequency signals, may control which of two or more antennas is being used to transmit radio-frequency signals, may control the process of routing incoming data streams over two or more antennas in device  10  in parallel, may tune an antenna to cover a desired communications band, etc. 
     Circuitry  28  may also control wireless transmit powers and maximum transmit power level settings based on sensor data and other information on the operating state of device  10 . For example, circuitry  28  may limit the maximum amount of power that may be transmitted by device  10  depending on which mode device is operating in. When device  10  is being operated near a user&#39;s body, maximum transmit power can be reduced. When device  10  is being operated away from the user&#39;s body, maximum transmit power can be increased. 
     In performing these control operations, circuitry  28  may open and close switches, may turn on and off receivers and transmitters, may adjust impedance matching circuits, may configure switches in front-end-module (FEM) radio-frequency circuits that are interposed between radio-frequency transceiver circuitry and antenna structures (e.g., filtering and switching circuits used for impedance matching and signal routing), may adjust switches, tunable circuits, and other adjustable circuit elements that are formed as part of an antenna or that are coupled to an antenna or a signal path associated with an antenna, may adjust power amplifier gain settings, may control transceiver output powers, and may otherwise control and adjust the components of device  10 . 
     Input-output circuitry  30  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Input-output circuitry  30  may include input-output devices  32 . Input-output devices  32  may include touch screens, buttons, joysticks, click wheels, scrolling wheels, touch pads, key pads, keyboards, light-emitting diodes and other status indicators, data ports, etc. Input-output devices  32  may also include sensors and audio components  42 . For example, input-output devices  32  may include an ambient light sensor such as ambient light sensor  29  of  FIG. 1A  for monitoring the amount of light in the environment surrounding device  10 . Input-output devices  32  may include a light-based proximity sensor such as a proximity sensor having an infrared light emitter and a corresponding infrared light detector for detecting reflected infrared light from external objects in the vicinity of device  10  or may include a capacitive proximity sensor or other proximity sensor structure (proximity sensor structure  31  of  FIG. 1A ). Input-output devices  32  may also include a gyroscope, an accelerometer, cameras such as front-facing camera  27  and rear-facing camera  33 , a temperature sensor, etc. Components  42  may include audio components such as speakers, tone generators, and vibrators (e.g., speakers such as speakerphone speaker  24  of  FIG. 1A  and ear speaker  18 ) or other audio output devices that produce sound. The audio components may also include microphones such as voice microphone  22  on the front face or lower end side wall of housing  12 , front-facing ambient noise reduction microphone  20  in ear speaker port  16 , and rear-facing microphone  35 . 
     During operation, a user can control the operation of device  10  by supplying commands through input-output devices  32  and may receive status information and other output from device  10  using the output resources of input-output devices  32 . 
     Wireless communications circuitry  34  may include radio-frequency (RF) transceiver circuitry formed from one or more integrated circuits, power amplifier circuitry, low-noise input amplifiers, passive RF components, one or more antennas, filters, duplexers, and other circuitry for handling RF wireless signals. Wireless signals can also be sent using light (e.g., using infrared communications). 
     Wireless communications circuitry  34  may include satellite navigation system receiver circuitry such as Global Positioning System (GPS) receiver circuitry  39  (e.g., for receiving satellite positioning signals at 1575 MHz) or satellite navigation system receiver circuitry associated with other satellite navigation systems. Wireless local area network transceiver circuitry such as transceiver circuitry  36  may handle 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communications and may handle the 2.4 GHz Bluetooth® communications band. Circuitry  34  may use cellular telephone transceiver circuitry  38  for handling wireless communications in cellular telephone bands such as bands in frequency ranges of about 700 MHz to about 2700 MHz or bands at higher or lower frequencies. Wireless communications circuitry  34  can include circuitry for other short-range and long-range wireless links if desired. For example, wireless communications circuitry  34  may include wireless circuitry for receiving radio and television signals, paging circuits, etc. Near field communications may also be supported (e.g., at 13.56 MHz). In WiFi® and Bluetooth® links and other short-range wireless links, wireless signals are typically used to convey data over tens or hundreds of feet. In cellular telephone links and other long-range links, wireless signals are typically used to convey data over thousands of feet or miles. 
     Wireless communications circuitry  34  may have antenna structures such as one or more antennas  40 . Antenna structures  40  may be formed using any suitable antenna types. For example, antenna structures  40  may include antennas with resonating elements that are formed from loop antenna structures, patch antenna structures, inverted-F antenna structures, dual arm inverted-F antenna structures, closed and open slot antenna structures, planar inverted-F antenna structures, helical antenna structures, strip antennas, monopoles, dipoles, hybrids of these designs, etc. Different types of antennas may be used for different bands and combinations of bands. For example, one type of antenna may be used in forming a local wireless link antenna and another type of antenna may be used in forming a remote wireless link. Antenna structures in device  10  such as one or more of antennas  40  may be provided with one or more antenna feeds, fixed and/or adjustable components, and optional parasitic antenna resonating elements so that the antenna structures cover desired communications bands. 
     Device  10  may be operated in a variety of positions relative to a user&#39;s body. As shown in  FIG. 3 , for example, when a user is making a telephone call, device  10  may be held adjacent to a head of a user (e.g., head  44 ). In this configuration, upper end  21  of device  10  is adjacent to ear  46  of the user, so that the user may listen to audio that is being played through speaker  18 . Lower end  19  is aligned with the user&#39;s mouth  50 . This allows the user&#39;s voice to be detected by microphone  22 . 
     Antennas  40  may include antennas in lower region  19  and/or in upper region  21 . As an example, device  10  may include an upper antenna in upper region  21  and a lower antenna in lower region  19 . The lower antenna in region  19  may be used as the primary transmitting antenna during voice telephone calls. The upper antenna in region  21  may be used as a secondary antenna. The antenna in lower region  19  may be spaced by a non-zero distance D (e.g., 5-30 mm) from head  44 . This is generally greater than the separation between the antenna in upper region  21  and the user&#39;s head, so it may be desirable to use antenna  19  as the primary transmitting antenna in device  10  to reduce wireless signal power at the user&#39;s head. 
     The operating mode shown in  FIG. 3  may sometimes be referred to as “at head” operating mode, because device  10  is being operated at head  44  of the user (i.e., adjacent to ear  46 ). Another illustrative operating mode for device  10  is shown in  FIG. 4 . In the scenario of  FIG. 4 , device  10  is resting on an inanimate support structure such as a table or other piece of furniture. Device  10  may, for example, be resting on upper surface  54  of table  52 . Table  52  and other inanimate support structures for device  10  may be formed from a material such a wood (e.g., a hard and rigid material). 
     When device  10  is being operated in speaker mode or when device  10  is being used for other functions that do not involve holding device  10  against the user&#39;s ear, device  10  may rest on a user&#39;s lap. As shown in  FIG. 5 , for example, device  10  may rest on surface  56  of leg  58 . Due to the soft and porous nature of clothing worn by the user and due to the presence of soft flesh in the user&#39;s leg, surfaces such as body surface  56  are typically softer and more likely to absorb high frequency sounds than the surface of a table such as table  52  of  FIG. 4 . This behavior of the user&#39;s clothing and body may be exploited when using sensors to detect the operating environment of device  10 . 
     The different operating modes of device  10  that are illustrated in  FIGS. 3, 4, and 5  may be used to determine correspondingly different maximum wireless transmit power levels to use for device  10 . 
     For example, when a user is using device  10  in an environment such as the table-top environment of  FIG. 4 , it may be desirable to operate device  10  at its maximum rated power (i.e., the maximum transmit power for device  10  may be set to an “unrestricted” level—i.e., a maximum value—that is selected based on regulatory limits for free space operation and carrier requirements, but that is not further limited by concerns about emissions into a nearby body part. 
     In an operating environment of the type shown in  FIG. 3 , device  10  (i.e., the lower antenna in region  19 ) is close to the user&#39;s body (i.e., head  44 ), but is typically separated by a distance D. In this scenario, it may be desirable to operate device  10  at a maximum transmit power level that is reduced by a first amount (e.g., 1-3 dB or other suitable amount) from the maximum (unrestricted) value of the maximum transmit power level. 
     In an operating environment of the type shown in  FIG. 5 , device  10  (e.g., the lower antenna in region  19 ) is generally closer to the user&#39;s body (e.g., leg  58 ) than in the operating environment of  FIG. 3 . Accordingly, it may be desirable to operate device  10  at a maximum transmit power level that is reduced by a second amount from the maximum (unrestricted) value of the maximum transmit power level (e.g., a maximum transmit power level that is reduced by 2-13 dB from the unrestricted maximum transmit level or by 1-10 dB from the maximum transmit level used in the “at head” operating mode). 
     Device  10  can use sensor data and other information on the current operating state of device  10  to ascertain which maximum transmit power level to use.  FIG. 6  is a schematic diagram of illustrative components in device  10  that may be used in monitoring the operating environment of device  10  and in enforcing corresponding maximum transmit levels for transmitted wireless signals. As shown in  FIG. 6 , device  10  may use transceiver circuitry  34 ′ and power amplifier  64  to generate wireless radio-frequency signals  62  that are wirelessly transmitted to wireless external equipment  60 . External equipment  60  may be wireless local area network equipment (e.g., equipment such as a wireless local area network base station), a cellular telephone base station, or other wireless base station. External equipment  60  may, if desired, include peer devices, network equipment, computers, handheld devices, etc. 
     Control circuitry  28  can control the amount of power Pt that is being transmitted wirelessly from antenna  40  by controlling the power P 1  of transceiver circuitry  34 ′ and by controlling the gain G of power amplifier  64 . Control circuitry  28  can determine in real time whether or not the output power Pt has reached a maximum transmit power limit. At output powers below the maximum transmit power, control circuitry  28  can increase and decrease the output power in real time based on received transmit power commands from external equipment  60 , based on received signal strength indicator information, based on sensor data, or based on other information. Whenever control circuitry  28  reaches a maximum transmit power limit Pmax, further increases in output power Pt will be capped (i.e., Pt is limited to Pmax and will not exceed Pmax). Because the amount of signal power that is transmitted is limited to the value of Pmax and cannot exceed Pmax, Pmax is sometimes referred to as the upper limit on transmitted power or the maximum transmitted power limit (maximum transmit power limit) for device  10 . 
     Control circuitry  28  can adjust the maximum transmit power Pmax in real time based on information on the operating state of device  10  and based on data from one or more sensors in input-output devices  32 . In the illustrative configuration of  FIG. 6 , device  10  has microphones such as front-facing microphone  20  and rear-facing microphone  35 . Device  10  also has accelerometer  66 . Front-facing microphone  20  can detect sound at the front face of device  10 . Rear facing microphone  35  can detect sound at the rear face of device  10 . Accelerometer  66  may be used to measure motion of device  10  (e.g., movement of the type that results when a user holds device  10  on the user&#39;s lap or rests device  10  on other body parts) and may be used to determine the direction of the pull of the Earth&#39;s gravity and thereby determine the orientation of device  10  relative to the Earth. 
     Whenever it is determined that ear speaker  18  is being used to play sound to the user, control circuitry  28  can determine that device  10  is likely being used in the “at ear” mode shown in  FIG. 3  (i.e., the user is making a voice telephone call). 
     Signals from accelerometer  66  may be used to determine whether device  10  is resting on a user&#39;s body.  FIG. 7  is a graph in which accelerometer data from accelerometer  66  has been plotted as a function of time. Accelerometer  66  may be, for example a three axis accelerometer that produces X, Y, and Z axis data. The accelerometer output signal in the graph of  FIG. 7  may correspond to a summation of the X, Y, and Z channels of the accelerometer, may correspond to a summation of the standard deviations of one second polling of the X, Y, and Z channel data, may be time averaged or otherwise time delayed (e.g., to implement a state persistence scheme in which abrupt state changes are filtered out—for example, after detecting when a device is placed on a table allowing the device to remain in the “on table” state until a large motion is detected) or may correspond to other functions of data from the X, Y, and/or Z channels. Line  68  corresponds to an accelerometer signal from device  10  in a configuration in which device  10  is resting on a table or other solid inanimate object such as table  52  of  FIG. 4 . Lines  70  and  72  correspond to accelerometer signals from device  10  in a configuration in which device  10  is resting on the body of a user (see, e.g., leg  58  of  FIG. 5 ). Lines  70  and  72  may be associated with different orientations of device  10  (e.g., portrait orientation versus landscape orientation, etc.). 
     To help device  10  discriminate between usage scenarios in which device  10  is resting on a part of a user&#39;s body and in which device  10  is resting on a structure such as a table, control circuitry  28  may compare the accelerometer output data from accelerometer  66  to a threshold value such as movement level threshold Ath of  FIG. 7 . In response to determining that the accelerometer data is less than movement threshold Ath, control circuitry  28  can conclude that device  10  is resting on table  52 . In response to determining that the accelerometer data is more than threshold Ath, control circuitry  28  can conclude that device  10  is not resting on table  52  and is therefore potentially resting on the body of a user. Larger accelerometer values (i.e., values larger than the values associated with lines  70  and  72 ) may be measured during active use of device  10  (e.g., when a user is walking, etc.). In these situations, control circuitry  28  can also conclude that device  10  is not resting on a table. 
     Device  10  may use acoustic information to further analyze how device  10  is being used by a user. For example, device  10  may emit audio signals (sound) using a speaker such as speaker  24  or other audio transducer (e.g., a vibrator, tone generator, speaker, or other audio signal source). Device  10  may then detect the emitted audio signals using one or more microphones in device  10  such as front-facing microphone  20  or rear-facing microphone  35 . The amount of audio that is detected in this type of scenario can reveal whether device  10  is resting on a table or other inanimate object or is possibly resting on a leg or other body part. 
     Consider, as an example, device  10  of  FIG. 8 . In this scenario, device  10  is resting on upper surface  74  of object  76 . The nature of object  76  is initially unknown to device  10 . Object  76  may be, for example, an inanimate object such as a table or may be a leg or other body part of a user. 
     As shown in  FIG. 8 , device  10  may have opposing surfaces  80 A and  80 B and opposing ends  19  and  21 . One of surfaces  80 A and  80 B may be the front face of device  10  and the other of surfaces  80 A and  80 B may be the rear face of device  10 . A user may place device  10  face up or face down on a surface, so the orientation of device  10  is not generally known in advance. 
     Microphones  78 A and  78 B may be located at end  21  of device  10 . Microphone  78 A may be located on surface  80 A of device  10 . Microphone  78 B may be located on opposing surface  80 B. One of microphones  78 A and  78 B may be front-facing microphone  20  and the other of microphone  78 A and  78 B may be rear-facing microphone  35 . 
     An audio source such as speaker  24  at lower end  19  of device  10  may emit sound  82  when it is desired to use audio sensing techniques to help determine the nature of the object on which device  10  is resting. To avoid creating an audible distraction for the user of device  10 , sound  82  is preferably out of the range of human hearing. For example, sound  82  may be an ultrasonic tone such as a tone at 30 kHz, a tone at a frequency from 20-100 kHz, a tone above 20 kHz, at tone at 20 kHz, or one or more ultrasonic tones at other ultrasonic frequencies. Lower frequency tones may also be used such as a tone at 10 kHz, etc. 
     The audio source that emits the ultrasonic signals may be a speaker such as speakerphone speaker  24  or ultrasonic audio signals may be emitted by other types of ultrasonic audio source (e.g., a tone generator). 
     Due to the presence of structure  76 , some of sound  82  (e.g., sound  82 ′) will pass through structure  76  and can be picked up by the downward facing microphone in device  10 . A significantly reduced amount of sound  82  (i.e., the sound that has been emitted outwards into the air around device  10 ) will reach the upward facing microphone in device  10 . 
     Accelerometer  66  may be used to determine the orientation of device  10 . In the example of  FIG. 8 , surface  80 A of device  10  is facing upward in direction Z and surface  80 B of device  10  is facing downward in direction −Z. Accelerometer  66  can measure the direction of the Earth&#39;s gravity and can use this information to determine whether microphone  78 A or microphone  78 B is currently the downward facing microphone. The downward facing microphone may then be used in monitoring the surroundings of device  10  for the possible presence of ultrasonic tones  82 ′. If ultrasonic signals  82 ′ are received by the downward facing microphone, device  10  can conclude that device  10  is resting on a table or other inanimate object. In the presence of a softer more sound absorbing structures  76  such as user&#39;s clothing and/or body, sound  82 ′ will be absorbed. If ultrasonic signals  82 ′ are not detected by the downward facing microphone, device  10  may conclude that there is a possibility that device  10  is not resting on an inanimate object and might be resting on a part of the body of a user. 
       FIGS. 9 and 10  are graphs showing how the audio information gathered using microphones  78 A and  78 B while generating ultrasonic audio signals using speaker  24  can be used to determine whether device  10  is resting on an inanimate object such as a table or is potentially resting on a part of a human body. To improve the signal-to-noise ratio of the audio system formed by the microphones and speaker, the audio information that is gathered by the microphones may be filtered with a low pass filter, a bandpass filter, or other filter to remove ambient noise other than the ultrasonic signals generated using the speaker. 
     The graph of  FIG. 9  corresponds to a configuration in which device  10  is resting on a user&#39;s leg. Dashed line  92  represents a baseline (average) level of sound that may be used as a detection threshold. Line  90  corresponds to sound from the upward facing microphone that is not blocked by the presence of the user&#39;s body. Line  94  corresponds to sound from the downward facing microphone that is resting on surface  76  and is blocked (absorbed) by surface  76  of  FIG. 8 . 
     The graph of  FIG. 10  corresponds to a configuration in which device  10  is resting on a hard inanimate surface such as a table. Dashed line  92  represents the baseline sound level that is used as the detection threshold. Line  98  corresponds to sound from the upward facing microphone (i.e., the unblocked microphone). Line  96  corresponds to sound from the downward facing microphone that is resting on surface  76  and is blocked by surface  76  of  FIG. 8 . 
     As the graphs of  FIGS. 9 and 10  demonstrate, the measured sound level (e.g., the amount of detected ultrasonic signal) by the unblocked (upward facing) microphone does not change appreciably between the table and body environments. The magnitude of curve  90  in  FIG. 9  is comparable to the magnitude of curve  96  of  FIG. 10 , because this signal level corresponds to sound that is passing between the speaker and the unblocked microphone through free space, rather than being transmitted through or near the surface on which device  10  is resting. As a result, the nature of surface  76  does not have a significant impact on the amount of sound detected by the unblocked microphone. Because data from the unblocked microphone is not sensitive to the nature of the surface on which device  10  is resting, device  10  preferably ignores data from the unblocked microphone. Instead, device  10  uses accelerometer  66  to identify the blocked (downward facing) microphone and uses the blocked microphone in gathering audio data. 
     Curve  94  of the graph of  FIG. 9  represents the audio signal measured by the blocked (downward facing) microphone when device  10  is resting on the user&#39;s body, whereas curve  96  of  FIG. 10  represents the audio signal measured by the blocked (downward facing) microphone when device  10  is resting on a table. The magnitude of curve  94  of  FIG. 9  is less than threshold  92 , because the sound (sound  82 ′) from speaker  24  is attenuated by the presence of the soft clothing and body tissue associated with the user&#39;s body. The magnitude of curve  96  in  FIG. 10  is greater than threshold  92 , because sound  82 ′ tends to be transmitted efficiently between speaker  24  and the blocked (downward facing) microphone through the table on which device  10  is resting. 
     Device  10  may therefore compare the amount of sound that is received by the blocked microphone to a predetermined threshold (e.g., threshold  92 ) to help determine whether device  10  is resting on a table or a user&#39;s body. If the detected sound level exceeds the threshold, device  10  can conclude that device  10  is resting on a table. If the detected sound level does not excess the threshold, device  10  can conclude that device  10  is not resting on the table and may therefore be resting on a user&#39;s body. 
       FIG. 11  is a diagram illustrating operations involved in using data from sensors and information on the operating state of device  10  in dynamically adjusting maximum transmit power levels. As shown in  FIG. 11 , device  10  may operate in modes  100 ,  102 , and  104 . In each of these modes, device  10  may use control circuitry  28  to analyze information about whether a user is using ear speaker  18 . Device  10  may also gather information from sensors  42 . For example, device  10  may gather information from accelerometer  66 . Motion data from accelerometer  66  (e.g., summed X, Y, and Z channel data, summed standard deviations of the X, Y, and Z channel data, etc.) may be gathered and orientation data from accelerometer  66  may be gathered (e.g., information indicating which side of device  10  is facing upward and which side of device  10  is facing downward). Speakerphone speaker  24  may generate ultrasonic audio, which may be detected using rear microphone  35  and/or front microphone  20 . The orientation data from accelerometer  66  may be used in identifying the downward facing microphone, so that signals from the upward facing microphone can be ignored. 
     Whenever it is determined that device  10  is playing audio through ear speaker  18 , device  10  may conclude that it is likely that the user is operating device  10  in an “at ear” mode of the type described in connection with  FIG. 3 . During the “at ear mode” (mode  100 ), the maximum transmit power level may be adjusted to a level that is appropriate for use when the user is holding device  10  against the user&#39;s face. As an example, the maximum transmit power for wireless signals may be adjusted to a level that is lowered by an amount ΔPL with respect to the value of Pmax that is used in unrestricted transmit scenarios (i.e., the maximum value of Pmax in device  10 ). During the operations of mode  100 , device  10  monitors accelerometer  66  to detect motion, compares the amount of detected motion to a predetermined motion threshold, monitors accelerometer  66  to determine the orientation of device  10 , generates ultrasonic audio signals with speakerphone speaker  24 , monitors the downward facing microphone (as determined by the orientation of device  10 ) to measure the ultrasonic audio signals, compares audio data gathered by the downward facing microphone to a predetermined ultrasonic audio signal threshold, and monitors the state of device  10  to determine whether or not audio is being played through ear speaker  18 . 
     In response to determining that audio is not being played through ear speaker  18 , device  10  can conclude that device  10  is not in the “at head” position, but rather might be resting against the body of the user or an inanimate object such as a table. 
     If no audio is being played through ear speaker  18  and if the amount of motion detected by the accelerometer is below the predetermined motion threshold and if the signal from the downward facing microphone is above the predetermined ultrasonic audio signal threshold, device  10  can conclude that device  10  is resting on a structures such as table  52  of  FIG. 4 . Device  10  can therefore transition from mode  100  to mode  102  (if operating in mode  100 ) or from mode  104  to mode  102  (if operating in mode  104 ), as indicated by line  108 . 
     During the “on table” mode, the maximum transmit power level may be adjusted to a level that is appropriate for use when the user is operating device  10  on an inanimate object such as a table. As an example, the maximum transmit power for wireless signals may be adjusted to a level that is equal to the maximum value of Pmax in device  10 . 
     During the operations of mode  102 , device  10  monitors accelerometer  66  to detect motion, compares the amount of detected motion to a predetermined motion threshold, monitors accelerometer  66  to determine the orientation of device  10 , generates ultrasonic audio signals with speakerphone speaker  24 , monitors the downward facing microphone (as determined by the orientation of device  10 ), compares audio data gathered by the downward facing microphone to a predetermined ultrasonic audio signal threshold, and monitors the state of device  10  to determine whether or not audio is being played through ear speaker  18 . 
     If no audio is being played through ear speaker  18  and if the amount of motion detected by the accelerometer is above the predetermined motion threshold and if the signal from the downward facing microphone is below the predetermined ultrasonic audio signal threshold, device  10  can conclude that device  10  is resting on a human body part such as the leg of the user. Device  10  can therefore transition from mode  100  to “on body” mode  104  (if operating in mode  100 ) or from mode  102  to mode  104  (if operating in mode  102 ), as indicated by line  110 . 
     During the “on body” mode, the maximum transmit power level may be adjusted to a level that is appropriate for use when the user is operating device  10  while device  10  is resting on the user&#39;s body. As an example, the maximum transmit power for wireless signals may be adjusted to a level that is lowered by an amount ΔPH with respect to the maximum (unrestricted) value of Pmax, where ΔPH is greater than ΔPL. 
     During the operations of “on body” mode  104 , device  10  monitors accelerometer  66  to detect motion, compares the amount of detected motion to a predetermined motion threshold, monitors accelerometer  66  to determine the orientation of device  10 , generates ultrasonic audio signals with speakerphone speaker  24 , monitors the downward facing microphone (as determined by the orientation of device  10 ), compares audio data gathered by the downward facing microphone to a predetermined ultrasonic audio signal threshold, and monitors the state of device  10  to determine whether or not audio is being played through ear speaker  18 . 
     If, during mode  102  or  104 , ear speaker  18  is switched into use, device  10  can transition to mode  100 , as indicated by line  106 . 
     In situations in which sensor data is not consistent, such as when motion data indicates that device  10  is resting on a table, but this is not corroborated by audio data from the downward facing microphone (i.e., the audio data is below the predetermined audio threshold) or such as when audio data from the downward facing microphone indicates that device  10  is resting on a table, but this is not corroborated by motion data (i.e., the motion data is above the motion threshold), the most conservative maximum transmit power level may be selected (i.e., it may be assumed, for the sake of being conservative, that device  10  is resting on the user&#39;s body). For example, device  10  may transition to mode  104  whenever there is ambiguity in the sensor data or other information about the operating state of device  10 . This is one example of a way in which ambiguous sensor data may be interpreted. Other actions may be taken if desired (e.g., sensor data may be measured again, additional sensors may be consulted, a user may be prompted for input on a touch screen display or other input-output device, etc.). 
     If desired, additional sensor data may be analyzed by control circuitry  28  to help determine the operating mode to use for device  10 . For example, control circuitry  28  can gather and analyze proximity sensor data, gyroscope data, Global Positioning System data, proximity sensor data, ambient light sensor data, touch sensor data, etc. The arrangement of  FIG. 11  is merely illustrative. 
     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.

Metadata:
Filing Date: 20170301
Publication Date: 20180828
Grant Date: 20180828
Priority Date: 20130502
Inventors: CABALLERO, RUBEN
DIVINCENT, MICHAEL
SEN, INDRANIL S.
SCHLUB, ROBERT W.
NARANG, MOHIT
VELASCO, RICARDO R.
CROWE, CHRISTOPHER B.
VERNON, SCOTT
Assignee: APPLE INC
CPC Classifications: [{"code": "H04B1/3838", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y02D70/166", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04B1/0343", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y02D70/40", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y02D70/23", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y02D70/144", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y02D70/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W52/282", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y02D70/142", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04B1/385", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y02D70/164", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W52/0209", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S15/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y02D70/26", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01S7/539", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R3/00", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04M2250/12", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04B1/0343", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B1/0343", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/0209", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R3/00", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04M2250/12", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04M2250/12", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04B1/385", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/282", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S7/539", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y02D30/70", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W52/0209", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/3838", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S15/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/3838", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y02D30/70", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 50687686