PATENT DOCUMENT

Publication Number: US-10045461-B1
Application Number: US-201514720169-A
Country: US
Kind Code: B1

Title: Electronic device with diaphragm cooling

Abstract:
An electronic device may be provided with electrical components such as a power supply that produce heat. Speakers and other components may be controlled using control circuitry within the electronic device. The electronic device may play audio signals through the speakers. Audio data may be received from external equipment or may be maintained locally within the device. A speaker such as a subwoofer may be mounted in a device housing above the power supply so that airflow from the speaker cools the power supply. To enhance cooling, the control circuitry may supply inaudible signals to the speaker that enhance airflow produced by the speaker. The inaudible signals may be supplied in response to detecting current heat-producing audio playback conditions, to predicting future heat-producing conditions, or real-time temperature measurements.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a housing defining a first opening and a second opening separate and distinct from the first opening; 
 an electrical component in the housing that produces heat; 
 a subwoofer comprising:
 a diaphragm, and 
 airflow biasing structures protruding from and distributed across a surface of the diaphragm; and 
 
 control circuitry configured to drive the diaphragm to generate a flow of air through the housing, the airflow biasing structures of the subwoofer helping to establish a direction of the flow of air through the housing that enters the housing through the first opening and exits the housing through the second opening. 
 
     
     
       2. The electronic device defined in  claim 1  wherein the control circuitry supplies subaudible drive signals to the subwoofer to produce the flow of air that cools the electrical component. 
     
     
       3. The electronic device defined in  claim 1  wherein the airflow biasing structures protrude from the diaphragm in an orientation that impedes air within the housing from flowing the second opening toward the first opening. 
     
     
       4. The electronic device defined in  claim 3  wherein the housing comprises a cylindrical housing having a first cavity to which the electrical component is exposed and a second cavity that forms a back volume for the subwoofer. 
     
     
       5. The electronic device defined in  claim 1  wherein the airflow biasing structures are a first plurality of airflow biasing structures and the electronic device further comprises a second plurality of airflow biasing structures protruding from an interior surface of the housing, the interior surface positioned proximate the diaphragm. 
     
     
       6. The electronic device defined in  claim 1  wherein adjacent ones of the airflow biasing structures are substantially parallel. 
     
     
       7. The electronic device defined in  claim 1  wherein the flow of air passes through a cavity defined by the housing, the first and second openings being disposed on different ends of the cavity. 
     
     
       8. The electronic device defined in  claim 7 , further comprising a heat emitting component disposed within the cavity, wherein the flow of air cools the heat emitting component. 
     
     
       9. The electronic device defined in  claim 2  further comprising a temperature sensor and wherein the control circuitry supplies the subaudible drive signals in response to measurements from the temperature sensor. 
     
     
       10. The electronic device defined in  claim 1  wherein the airflow biasing structures protrude from the diaphragm into a channel terminating at the second opening. 
     
     
       11. The electronic device defined in  claim 1  wherein the airflow biasing structures include flexible structures. 
     
     
       12. The electronic device defined in  claim 11  wherein the flexible structures include flexible structures selected from the group consisting of: flexible layers of fabric and flexible layers of plastic. 
     
     
       13. The electronic device defined in  claim 1  wherein the airflow biasing structures include sloped sidewall surfaces on at least a selected one of the first opening and the second opening. 
     
     
       14. An apparatus, comprising:
 a housing; 
 a speaker mounted in the housing that produces airflow during operation of the apparatus and having a diaphragm that extends across an interior cavity defined by the housing to divide the interior cavity into a first volume of air and a second volume of air; 
 a heat-producing electrical component that is mounted within the first volume of air and that is cooled by the airflow; and 
 airflow biasing structures protruding from the diaphragm and into the first volume of air, the airflow biasing structures assisting in guiding the airflow produced by the speaker into the first volume through a first opening defined by the housing and then out of the first volume through a second opening defined by the housing, wherein the second opening is different than the first opening and the airflow biasing structures protrude from the diaphragm in an orientation that impedes air within the housing from flowing from the second opening toward the first opening. 
 
     
     
       15. The apparatus defined in  claim 14  further comprising:
 control circuitry that drives the speaker with a subaudible signal to help produce the airflow and enhance cooling of the heat-producing electrical component with the airflow. 
 
     
     
       16. The apparatus defined in  claim 15  wherein the control circuitry analyzes audio content that is to be played through the speaker and produces the subaudible signal in response to predicting future heat production by the heat-producing electrical component from analyzing the audio content. 
     
     
       17. The apparatus defined in  claim 16  wherein the first and second openings are disposed on different ends of the first volume of air. 
     
     
       18. The apparatus defined in  claim 14  wherein the airflow biasing structures are configured to oscillate with the diaphragm. 
     
     
       19. The apparatus defined in  claim 18  wherein the heat-producing electrical component comprises a power supply. 
     
     
       20. The apparatus defined in  claim 14  wherein the housing has a plurality of openings in which electrical components are mounted. 
     
     
       21. The apparatus defined in  claim 14  wherein the housing has at least one air entrance opening and at least one air exit opening and wherein the airflow biasing structures cause more of the airflow to enter the air entrance opening and exit the air exit opening than enters the air exit opening and exits the air entrance opening. 
     
     
       22. The apparatus defined in  claim 21  wherein the airflow biasing structures include at least one flexible member. 
     
     
       23. A speaker, comprising:
 a housing; 
 a subwoofer within an interior cavity of the housing, the subwoofer comprising a diaphragm; 
 a power supply disposed within the interior cavity of the housing that is cooled by airflow from the subwoofer; and 
 airflow biasing structures protruding from and distributed across a surface of the diaphragm, the airflow biasing structure helping to guide an airflow generated by the subwoofer into the interior cavity through a first opening of the housing and then out of the interior cavity through a second opening of the housing. 
 
     
     
       24. The speaker defined in  claim 23  further comprising:
 wireless communications circuitry that receives digital audio data; and 
 control circuitry that predicts future heat production by the power supply based on analysis of the received digital audio data and that controls the subwoofer based at least partly on the predicted future heat production. 
 
     
     
       25. The speaker defined in  claim 24 , further comprising:
 a temperature sensor, 
 wherein the control circuitry controls the subwoofer based at least partly on temperature measurements from the temperature sensor. 
 
     
     
       26. The speaker defined in  claim 23  wherein the airflow biasing structures impede air from flowing from the second opening and toward the first opening.

Description:
This application claims the benefit of provisional patent application No. 62/057,645, filed Sep. 30, 2014, which is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     This relates generally to electronic devices, and, more particularly, to managing heat produced by electrical components in electronic devices. 
     Electronic devices include electrical components such as integrated circuits, and other circuitry. This circuitry may be used in forming communications circuits, control circuits, power supplies, and other circuits within an electronic device. During operation, the circuitry of an electronic device produces heat. Excess heat can damage device components, so the heat that is produced by the circuitry should be removed from the device. 
     It can be challenging to design a cooling system for an electronic device. Some cooling systems produce undesirable levels of noise. Noise can interfere with the use of the electronic device. Other cooling systems may produce insufficient amounts of cooling. When a device is cooled insufficiently, there is a risk that parts may overheat and cause damage. 
     It would therefore be desirable to be able to provide improved cooling techniques for electronic devices that include heat producing components. 
     SUMMARY 
     An electronic device may be provided with electrical components that produce heat during operation. The electrical components may include a power supply for the electronic device. 
     The electronic device may have a housing in which electrical components are mounted. For example, an array of electrical components may be mounted in openings on housing sidewalls. Speakers such as subwoofers may be mounted at the upper and lower ends of the housing or elsewhere within the device. 
     Speakers and other components in the electronic device may be controlled using control circuitry within the electronic device. The control circuitry may play audio signals through the speakers. Audio data may be received from external equipment or may be obtained locally within the device. 
     A speaker such as a subwoofer may be mounted in the housing above a heat-producing component such as a power supply so that airflow from the speaker can cool the component. To enhance cooling, the control circuitry may supply signals to the speaker that enhance airflow produced by the speaker. The signals may be inaudible or nearly inaudible to a user. The inaudible or nearly inaudible signals may be supplied in response to detecting current heat-producing audio playback conditions, to predicting future heat-producing conditions, or real-time temperature measurements. 
     Airflow biasing structures may be provided to encourage air to flow in a desired direction during movement of the speaker. The airflow biasing structures may cause more airflow to be directed into air entrance openings and out of air exit openings than flows out of air entrance openings and into air exit openings. Establishing airflow in a desired direction through the housing may help efficiently cool hot components with cool air entering the housing while exhausting corresponding heated air. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an illustrative system in accordance with an embodiment. 
         FIG. 2  is a partly cut-away side view of an illustrative electronic device in accordance with an embodiment. 
         FIG. 3  is a diagram of an illustrative heat sink structure mounted adjacent to a speaker in accordance with an embodiment. 
         FIG. 4  is a diagram showing how an upper speaker and lower speaker may have diaphragms that move in opposing directions in accordance with an embodiment. 
         FIG. 5  is a diagram showing how an upper speaker and lower speaker may have diaphragms that move in tandem during cooling operations in accordance with an embodiment. 
         FIG. 6  is a flow chart of illustrative steps involved in operating an electronic device in accordance with an embodiment. 
         FIG. 7  is a cross-sectional side view of a portion of an illustrative electronic device with airflow biasing structures in accordance with an embodiment. 
         FIG. 8  is a cross-sectional side view of a portion of another illustrative electronic device with airflow biasing structures in accordance with an embodiment. 
         FIG. 9  is a cross-sectional side view of a portion of an electronic device with airflow biasing structures of the type that may be formed from shaped passageways through a housing wall or other structure in accordance with an embodiment. 
         FIG. 10  is a cross-sectional side view of an illustrative electronic device with additional airflow biasing structures in accordance with an embodiment. 
         FIG. 11  is a cross-sectional side view of an illustrative electronic device with airflow biasing structures that encourage air to flow into and out of respective airflow entrances and airflow exits in a housing in accordance with an embodiment. 
         FIG. 12  is cross-sectional side view of an illustrative electronic device with flexible airflow biasing structures in accordance with an embodiment. 
         FIG. 13  is a side view of a passageway in an electronic device that has been provided with flexible airflow biasing structures in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An electronic device may have electrical components that produce heat during operation. The electronic device may have a cooling system that uses one or more speakers to move air and thereby help cool the components. Speakers can move air when playing audio content during normal operation and can move air when driven using subaudible frequencies. 
     If desired, cooling operations may be regulated dynamically based on temperature measurements or based on information on current or future thermal loads. Thermal load predictions may be made, for example, by analyzing digital audio content before or during the playback of audio content for a user. In some situations, an electronic device may receive audio to be played back from external equipment. Electronic devices may also play locally stored audio content. 
     An illustrative system that includes electronic devices is shown in  FIG. 1 . As shown in  FIG. 1 , system  8  may include one or more electronic devices such as electronic device  10 . Device  10  may include one or more speakers and may play audio content for a user. External equipment (see, e.g., electronic device  10 ′) may, if desired, provide electronic device  10  with data. For example, electronic device  10 ′ may provide audio data to device  10  that device  10  plays to a user. The audio data may be accompanied by corresponding video content or may be a music file or other audio content that is not accompanied by video information. 
     Electronic device  10  (and/or device  10 ′) may be a computing device such as a laptop computer, a computer monitor containing an embedded computer, a tablet computer, a cellular telephone, a media player, or other handheld or portable electronic device, a smaller device such as a wrist-watch device, a pendant device, a headphone or earpiece device, a device embedded in eyeglasses or other equipment worn on a user&#39;s head, or other wearable or miniature device, a television, a computer display that does not contain an embedded computer, a gaming device, a navigation device, an embedded system such as a system in which electronic equipment with a display is mounted in a kiosk or automobile, a stand-alone speaker, a speaker implemented as part of other equipment, equipment that implements the functionality of two or more of these devices, or other electronic equipment. 
     As shown in  FIG. 1 , electronic device  10  (and device  10 ′) may have control circuitry  16 . Control circuitry  16  may include storage  20  and may have processing circuitry  22  for supporting the operation of device  10 . Storage  20  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  22  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 and other wireless communications circuits, power management units, audio chips, application specific integrated circuits, etc. 
     Input-output circuitry in device  10  such as input-output devices  18  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 devices  18  may include buttons, joysticks, scrolling wheels, touch pads, key pads, keyboards, microphones, speakers, tone generators, vibrators, cameras, sensors such as touch sensors, proximity sensors, ambient light sensors, compasses, gyroscopes, accelerometers, light-emitting diodes and other status indicators, data ports, etc. A user can control the operation of device  10  by supplying commands through input-output devices  18  and may receive status information and other output from device  10  using the output resources of input-output devices  18 . If desired, a user may control the operation of device  10  using input-output devices  18  and other resources in device  10 ′. As an example, device  10  may be an accessory such as a speaker or other output device with a speaker and device  10 ′ may be a host device such as a computer, cellular telephone, or set-top box. In this type of scenario, a user may interact with device  10  by supplying commands and other input to device  10 ′. Arrangements in which a user interacts with both device  10  and  10 ′ may also be used (e.g., to allow a user to make a volume adjustment or other audio content playback adjustment using input-output resources associated with device  10  and/or on device  10 ′). 
     Input-output devices  18  may include one or more displays. Device  10  (or device  10 ′) may, for example, include a touch screen display that includes a touch sensor for gathering touch input from a user or a display that is insensitive to touch. A touch sensor for a display in device  10  or device  10 ′ may be based on an array of capacitive touch sensor electrodes, acoustic touch sensor structures, resistive touch components, force-based touch sensor structures, a light-based touch sensor, or other suitable touch sensor arrangements. 
     Power for device  10  (and device  10 ′) may be provided by an external source of power and/or an internal battery. The components for devices  10  and  10 ′ such as circuitry  16  and devices  18  and other structures may be implemented using integrated circuits, discrete components (e.g., resistors, capacitors, and inductors), microelectromechanical systems (MEMS) devices, portions of housing structures, packaged parts, and other devices and structures. If desired, some of these components may be omitted (e.g., to simplify either device  10 ′ or device  10 ). For example, device  10 ′ may include a display and device  10  may not include a display, etc. 
     Control circuitry  16  may be used to run software on devices  10  and  10 ′ such as operating system code and applications. During operation of devices in system  8  such as devices  10  and  10 ′, the software running on control circuitry  16  may display images for a user on an optional display and may use other internal components such as input-output devices  18 . For example, electronic device circuitry such as audio circuits may be used to play audio through one or more speakers in device  10  (or  10 ′). Devices  10  and  10 ′ may use communications circuits to send and receive wireless and wired data over a communications link within communications network  24 . Devices  10  and  10 ′ may, for example, use wireless circuits in circuitry  16  (e.g., a baseband processor and associated radio-frequency transceiver circuitry) to transmit and receive wireless signals. Devices  10  and  10 ′ may transmit and receive cellular telephone signals and/or wireless local area network signals or other wireless data (e.g., Bluetooth® data, wireless data shared over an IEEE 802.11 link, etc.). As an example, device  10 ′ may wirelessly stream audio content to device  10  and device  10  may play this audio content for a user using speakers within device  10 . Device  10  may also play audio content that has been stored locally within storage  20  in device  10 . 
     A partly cut-away side view of an illustrative electronic device is shown in  FIG. 2 . As shown in  FIG. 2 , 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.). Device  10  may have inner housing structures that provide additional structural support to device  10  and/or that serve as mounting platforms for printed circuits and other structures. Structural internal housing members may sometimes be referred to as housing structures and may be considered to form part of housing  12 . 
     Housing  12  may have a shape with planar sides, curved sides, or combinations of planar and curved sides. As an example, housing  12  may be cylindrical and may have a cylindrical wall that surrounds axis  70  or may have a box-shape having four sides with four corresponding planar walls. Housing walls of other shapes may also be used (e.g., spherical shapes, pyramidal shapes, etc.). Housing  12  may have an elongated shape that extends along axis  70  (i.e., axis  70  may serve as the longitudinal axis for device  10  as well as the central axis of a cylindrical housing) or may have a non-elongated shape. 
     The housing wall for housing  12  may have openings that receive one or more components such as components  40 . Components  40  may be light-based components (e.g., light-emitting diodes, displays, lamps, light-based status indicator components, light-based proximity sensors, etc.), sensors (e.g., ambient light sensors, capacitive proximity sensors, touch sensors, force sensors, microphones and other audio sensors), speakers (e.g., tweeters, mid-range drivers, other middle-to-high frequency speakers, woofers, etc.), or other suitable components. There may be any suitable number of components  40  in device  10  (e.g., one or more, two or more, five or more, ten or more, 50 or more, 10-40, fewer than 100, more than 60, etc.). Components  40  may be mounted in the upper portion of device (e.g., in an array of rows and columns that wraps around the exterior of device  10 ) or may be mounted in other portions of device  10 . The configuration of  FIG. 2  is merely illustrative. 
     It may be desirable to provide device  10  with the capability to reproduce low-frequency sounds. Accordingly, device  10  may be provided with one or more subwoofers such as subwoofers  42  and  44  or other speakers capable of producing low-frequency sounds (e.g., sounds below 40 Hz, below 35 Hz, from 20-50 Hz, above 15 Hz, etc.). Subwoofer  42  may, for example, be oriented upwards to produce sound in direction  58 , whereas subwoofer  44  may be oriented downwards to produce sound in direction  60 . Arrangements with fewer than two subwoofers or more than two subwoofers may also be used. 
     To prevent interference between subwoofers such as subwoofers  42  and  44  and components  40 , it may be desirable to provide device  10  with an isolation wall such as inner wall  66  between components  40  and subwoofers  42  and  44 . Inner wall  66  may, as an example be a hollow tube or other cylindrical wall. The presence of inner wall  66  within housing  12  may create an annular cavity such as cavity  68  between the exterior surface of wall  66  and the opposing interior surface of the wall of housing  12 . Cavity  68  may be exposed to the rear portions of components  40 . Wall  66  serves to separate annular cavity  68  from interior cavity  64 . The rears of subwoofers  42  and  44  are exposed to cavity  64 , so cavity  64  may sometimes be referred to as the back volume of subwoofers  42  and  44  (i.e., the subwoofer back volume of device  10 ). Cavity  64  may have a cylindrical shape, may have a box shape, may be a volume surrounded by planar and curved sides, etc. In configurations of the type shown in  FIG. 2 , there are no air passages between cavities  64  and  66 , so cavities  64  and  66  are isolated from each other. 
     Subwoofer  42  is open to the air surrounding device  10  and can therefore radiate sound upward in direction  58 . Subwoofer  44  faces in direction  60  and can therefore radiate sound downward in direction  60  into cavity  62 . The sound produced by subwoofer  44  may exit cavity  62  into the air surrounding device  10  through openings  56  in housing  12 . Due to the presence of openings  56  (i.e., openings that connect cavity  62  to outside ambient air), cavity  62  is not sealed, so air can flow into and out of cavity  62  (i.e., cavity  62  is vented). 
     Device  10  may include electrical components such as components  46  and  48 . Components  46  and  48  may include integrated circuits, discrete components such as resistors, capacitors, and inductors, switches, electromechanical components, audio circuits such as amplifiers, digital-to-analog converters, and filters, power supply components such as transformers, digital signal processors, communications circuits, and other circuitry and components (see, e.g., circuitry  16  and devices  18  of  FIG. 1 ). Components  46  and  48  may be mounted in any suitable location within device  10 . As an example, component(s)  46  may be mounted in cavity  64  and component(s)  48  may be mounted in cavity  62 . With one suitable arrangement, component  48  may be a power supply and component(s)  46  may be signal processing components for performing digital and/or analog processing operations on audio content (e.g., digital communications circuitry for receiving audio content from external equipment  10 ′ and/or local sources, digital signal processing circuitry for processing received digital data, analog circuits such as audio signal amplifiers for driving signals into speakers in device  10  such as components  40  and speakers  42  and  44 , or other suitable components). In general, components  46  and  48  may be any suitable electrical components in device  10 . Configurations in which component(s)  46  is used in forming control circuitry  16  and in which component(s)  48  is a power supply are sometimes described herein as an example. 
     The components within device  10  may produce heat during operation. For example, power supply  48  may generate considerable amounts of heat, particularly when audio content is being played through the speakers of device  10 . Subwoofers  42  and  44  can draw substantial power when bass-heavy content is being played. Heat production in device  10  can be monitored in real time using temperature sensors such as temperature sensor  50  in components  46 , temperature sensor  52  in power supply  48 , or other temperature sensors in device  10 . Control circuitry  16  can gather real time temperature measurements and can take action to cool heat-producing components when a temperature rise of more than a predetermined amount is detected. Control circuitry  16  can also take action to cool heat-producing components based on estimates of current and future heat production obtained by analyzing audio data during audio playback operations. 
     To help cool a heat-producing electrical component such as power supply  48 , power supply  48  may be mounted in the vicinity of a speaker in device  10  such as subwoofer  44  (i.e., under subwoofer  44  and within cavity  62  in the configuration of  FIG. 2 ). During operation of subwoofer  44 , the movement of the diaphragm of subwoofer  44  will cause air to flow over power supply  48  that cools power supply  48 . In particular, when subwoofer  44  is driven downwards in direction  60 , air will be pushed downwards in direction  60  and will flow past power supply  48 . A heat sink structure such as heat sink  54  of  FIG. 2  may be provided with fins or other structures that help convey heat away from power supply  48  when exposed to the airflow created by movement of subwoofer  44 . Hot air may be expelled through openings  56  and cool air may be drawn into cavity  62  through openings  56  to facilitate cooling. 
     The location of power supply  48  adjacent to subwoofer  44  allows subwoofer  44  to cool power supply  48 . In particular, cooling is enhanced by mounting power supply  48  in a position that allows airflow generated by subwoofer  44  to pass over heat sink  54  and other portions of power supply  48 . When device  10  is being lightly used (e.g., when audio content with minimal bass content is being played or when no audio content is being played), subwoofer  44  may be at rest. When device  10  is being more heavily used (e.g., when audio content with more bass content is being played or when audio is being amplified to high volume levels), the amount of heat produced by power supply  48  may increase, while at the same time the amount of airflow (and therefore cooling) that is generated by subwoofer  44  may increase. The positioning of power supply  48  and subwoofer  44  adjacent to one another within device  10  therefore serves to provide cooling to power supply  48  when needed, even in the absence of additional optional thermal management operations. 
     To enhance cooling from subwoofer  44 , it may be desirable to place heat sink  54  in a location that is separated by a relatively small distance D from the position at which diaphragm  74  of subwoofer  44  reaches its maximum excursion (see, e.g., position  72  of  FIG. 3 ). Distance D may be, for example, less than 50 cm, less than 25 cm, less than 10 cm, less than 5 cm, or less than 2 cm. 
     In addition to providing cooling to power supply  48  from the normal operation of subwoofer  44 , control circuitry  16  in device  10  (see, e.g., components  46 ) may regulate the operation of subwoofers  42  and/or  44  to facilitate cooling. For example, control circuitry  16  may dynamically control subwoofer  44  to produce airflow that cools power supply  48 . Dynamic control operations such as these may, as an example, be performed by monitoring and analyzing the audio content that is being played or that is to be played with the speakers of device  10 . Digital content analysis can be performed by control circuitry  16  on digital audio data that is being stored in storage  20  of device  10 . The digital audio data stored in storage  20  may include locally stored content (e.g., digital audio files) or may include streaming content that is being received from external device  10 ′ (e.g., a portion of a digital audio file that has been received and buffered in storage  20  in advance of being played on device  10 ). Because digital information on the content to be played on device  10  is available in advance of playback, control circuitry  16  can analyze future content. Device  10  may, for example, determine whether or not particular bass-heavy content or other heat-producing content is about to be played by device  10 . Based on currently played content and/or based on future content, device  10  can control the operation of subwoofer  42  and/or subwoofer  44  to ensure that power supply  48  is adequately cooled. 
     If, for example, control circuitry  16  detects content that includes heavy bass content or other content that will result in increased heat production by power supply  48 , device  10  can take appropriate action. Action can be taken either while the bass-heavy content is being played or in advance to prepare for the upcoming playback of the bass-heavy content. Action can also be taken while other content is being played (e.g., classical music with little or no bass) or in advance of playing back such content. Even when playing low-base content, the amount of heat being produced by power supply  48  may be sufficient to warrant cooling by subwoofer  44 . By using control circuitry  16  to detect and/or predict the playback of this heat-producing content, subwoofer  44  can be activated to produce airflow and thereby cool power supply  48 , even when subwoofer  44  would not otherwise be active or would not be sufficiently active to cool power supply  48  as much as desired. 
     To prevent subwoofer cooling operations from creating an audible disturbance (i.e., an audio signal that is not part of the audio content that is being played back), control circuitry  16  can drive subwoofer  44  at a low frequency such as a frequency below the normal range of human hearing. The lowest frequency at which humans are generally said to be able to hear audio signals is about 20 Hz. Accordingly, by driving subwoofer  44  at frequencies at or below 20 Hz, the amount of undesired acoustic signal that is produced by subwoofer  44  when it is being driven to create a cooling airflow can be minimized or avoided completely. For example, control circuitry  16  can drive subwoofer  44  at an inaudible frequency (e.g., a frequency below 20 Hz, below 10 Hz, from 5-20 Hz, above 4 Hz, or below 15 Hz) whenever digital signal analysis on the audio content that is being played or to be played indicates the power supply  48  will be producing excessive amounts of heat and will not be sufficiently cooled by normal movement of subwoofer  44 . Subaudible (barely audible) signals such as low-volume signals at 40 Hz, 50 Hz, or other frequencies can also be used as cooling signals. 
     Insufficient cooling scenarios may arise either because subwoofer  44  would normally be inactive due to the lack of bass content in the audio signal or because subwoofer  44  would normally be only slightly active due to the presence of small amounts of bass content in the audio signal. In either case, control circuitry  16  can apply a subaudible signal (i.e., an inaudible signal or nearly inaudible signal) to subwoofer  44  (e.g., a signal below 20 Hz) so that the amount of airflow from subwoofer  44  is increased sufficiently to provide desired cooling to power supply  48 . 
     During normal movement of subwoofers  42  and  44  to play audio to a user, subwoofers  42  and  44  move in opposite directions, as shown in  FIG. 4 . For example, subwoofer  42  may move up while subwoofer  44  is moving down or subwoofer  42  may move downwards at the same time that subwoofer  44  is moving upwards. For enhanced efficiency in cooling power supply  48  (e.g., when a subaudible signal is being driven into subwoofer  42  and when little or no bass content is being played back using subwoofer  42 ), control circuitry  16  may drive subwoofers  42  and  44  in tandem (i.e., so that their diaphragms move in the same direction), as shown in  FIG. 5 . For example, subwoofers  42  and  44  may move up together and may move down together. This type of tandem motion consumes less energy than normal operations of the type shown in  FIG. 4  and may therefore help reduce the load on subwoofers  42  and  44  and the resulting heat produced by power supply  48  by driving subwoofers  42  and  44  out of phase from each other as depicted in  FIG. 5 . 
     Illustrative steps involved in operating device  10  in a system such as system  8  of  FIG. 1  or other operating environment are shown in  FIG. 6 . In scenarios in which device  10  is playing back audio content from local storage (e.g., an audio file stored in a hard drive, solid state memory, or other local storage media), control circuitry  16  can obtain the audio content to be played from storage  20  in device  10 . In scenarios in which it is desired for device  10  to play back audio content that is provided from external device  10 ′, device  10 ′ may, at step  90 , transmit (e.g., stream) the audio data to device  10  over network  24 . Network  24  may be a wired or wireless connection between devices  10 ′ and  10 . As an example, network  24  may include a wired local area network, a peer-to-peer cable between devices  10 ′ and  10 , a wireless local area network, or other suitable communications path. The information that device  10 ′ transmits to device  10  at step  90  may be audio content such as a song, audible book, radio station, a video with audio content, a telephone call, a video call with audio content, or other data that results in heating of power supply  48  or other circuitry in device  10 . The transmission of the audio data or other data from device  10 ′ to device  10  may take place continuously (see, e.g., line  92  of  FIG. 6 ), may take place periodically, or may take place in response to satisfaction of predetermined criteria. 
     Audio content and other information that is transmitted during the operations of step  90  may be received by device  10  and stored in a buffer implemented in storage  20  on device  10  at step  94 . The reception of the audio data from device  10 ′ may take place continuously as content is being streamed, as illustrated by line  96 . Data may also be received and stored for later playback, if desired. 
     As indicated by step  98  and line  100 , control circuitry  16  may continuously retrieve audio data from the buffer in storage  20  and may play this audio through the speakers of device  10 . For example, control circuitry  16  may use digital-to-analog converter circuitry to convert digital audio data into analog signals and may use audio amplifiers to amplify the audio signals. The amplified audio signals may be used to drive speakers  42 , and  44  and other audio components (e.g., a speaker in components  40 , speakers elsewhere in device  10 , and/or other audio transducer components). 
     As the audio content is being buffered in storage  20  and played back at step  98 , control circuitry  16  may retrieve and analyze some or all of the buffered data (step  102 ). The analysis operations may take place on the audio data that is currently being played through the speakers of device  10  and/or or may take place on data (i.e., future data) that has been retrieved for analysis but which has not yet been converted to analog signals and played for the user. 
     In some situations, audio signal analysis during the operations of step  102  will reveal that bass content is present (or will shortly be present) in the audio being played, so control circuitry  16  can conclude that subwoofer  44  will be in motion. Nevertheless, the analysis of the audio signal may also reveal that the movement expected of subwoofer  44  due to the anticipated motion will be insufficient to cool power supply  48  as much as desired. This may occur, for example, when the audio content being played back is sufficient to create a heat rise, but contains relatively little bass content. When control circuitry  16  detects that this type of scenario has arisen or is about to arise, control circuitry  16  can drive subwoofer  44  with subaudible signals (e.g., signals at inaudible frequencies or nearly inaudible signals) to supplement the movement of subwoofer  44  (step  104 ). To avoid interference with bass content being played by device  10 , bass content can be routed to subwoofer  42  (e.g., while subaudible cooling signals are being provided to subwoofer  44 ) or bass playback can be momentarily suspended. If desired, control circuitry  16  may supply the subaudible (e.g., inaudible or nearly inaudible) drive signals to subwoofers  42  and  44  and may drive subwoofers  42  and  44  in a tandem configuration (diaphragms moving in the same direction in unison) to enhance efficiency, as described in connection with  FIG. 5 . Control circuitry  16  can also drive subwoofer  44  (and/or subwoofer  44 ) with subaudible signals to produce cooling airflow in response to detection of temperature measurements from temperature sensors such as sensors  50  and  52  that indicate that the temperature within device  10  is becoming too high. In general, control operations to cool power supply  48  may be performed based on temperature measurements, based on a predetermined schedule, based on analysis of audio data, based on user commands or commands from external device  10 ′, or based on any other criteria. Actions that may be taken in response include rerouting bass content or other heat-producing content to appropriate subwoofers or other speakers within device  10 , temporarily suppressing bass content or other heat-producing content, providing subwoofers  42  and/or  44  with subaudible drive signals to produce cooling airflow, etc. As shown by line  106 , processing may then loop back to step  102 , so that additional audio data can be processed. 
     If desired, device  10  may be provided with airflow biasing structures that help establish a desired air flow pattern within device  10  during movement of speakers (e.g., during subwoofer diaphragm movement or movement of other speaker diaphragms) to promote cooling. 
     Consider, as an example, the arrangement of illustrative device  10  that is shown in the cross-sectional side view of  FIG. 7 . As shown in  FIG. 7 , speaker (speaker diaphragm)  44  and portions of opposing structure  202  (e.g., internal device structures, portions of housing  12 , etc.) may be provided with airflow biasing features such as airflow biasing structures  200 . Structures  200  may be fins or other protruding members, protrusions with sloped surfaces, structures with asymmetric curved surfaces, or any other structures that promote asymmetric movement of air within device  10  in response to reciprocation of speaker  44  in directions  206 . 
     Housing  12  may have passageways that serve as one or more entrances and one or more exits for air. In the illustrative arrangement of  FIG. 7 , housing  12  has openings such as openings  210  that serve as airflow entrances and openings such as openings  208  that serve as airflow exits (e.g., exhausts for air that has become heated by internal device components). During operation of speaker  44 , speaker  44  moves back and forth in directions  206 . Due to the angled shapes or other airflow biasing shapes of airflow biasing structures  202 , movement of speaker  44  causes more air to flow in direction  212  on average than in direction  214 . As a result, a flow of air is established through device  10  that cools the internal components of device  10  (i.e., cool air is drawn into the interior of housing  12  in directions  218  through entrances  210  and hot air is forced out of housing  12  in directions  216  through exits  208 . 
     In the illustrative example of  FIG. 8 , airflow biasing structures  200  have a shape that forms an array of openings  220  between an upper portion of the interior of housing  12  and a lower portion of the interior of housing  12  that contains component  48  and heat sink  54 . The asymmetric shape of structures  200  (which have convex surfaces that protrude downwards in the configuration of  FIG. 8 ) causes air to flow more through openings  220  in upwards direction  212  than in downwards direction  214 , thereby establishing a flow of cool air  218  through entrance  210  and hot air  216  through exit  208 . 
     The cross-sectional side view of the electronic device of  FIG. 9  shows how openings in housing  12  such as entrances  210  and exits  208  may have sloped sidewall surfaces that form airflow biasing structures  200  that cause air to preferentially flow inwardly (as with entrances  210 ) or outwardly (as with exits  208 ). The illustrative airflow biasing structures of  FIG. 9  may be formed on housing  12  or on internal device structures that cover openings in housing  12 . 
       FIG. 10  shows an illustrative configuration in which airflow biasing structures  200  are formed under speaker  44 . Structures  200  may have shapes that promote more airflow in directions  212  than in directions  214 , thereby causing cool air  218  to enter housing  12  through entrances  210  and corresponding heated air  216  to exit housing  12  through exits  208 . 
     Another illustrative airflow biasing configuration for device  10  is shown in  FIG. 11 . As shown in  FIG. 11 , airflow biasing structures  200  have a curved shape that causes more air to flow upwards and outwards in directions  214  than downwards and inwards in directions  212 . As a result, airflow is established through housing  12  in which cool air  218  enters housing  12  through entrances  210  and hot air  216  exits housing  12  through exits  208 . 
     If desired, flexible structures such as one or more layers of flexible fabric, flexible layers of plastic, or other flexible members may be configured to serve as airflow biasing structures  200 . This type of arrangement is shown in  FIG. 12 . In the example of  FIG. 12 , airflow biasing structures  200  have been formed from inwardly slanting and outwardly slanting flexible layers that serve as one-way air flow valves for the openings in housing  12 . Structures  200  have orientations that promote more air flow in directions  212  than in directions  214 , so that cool air  218  enters housing  12  through entrances  210  and hot air  216  is expelled from housing  12  through exits  208  due to motion of speaker  44  in directions  206 . 
       FIG. 13  is a side view of a portion of housing  12  having an opening  250  (i.e., an exit or entrance opening) that is covered with flexible panels of fabric, plastic, or other layers of flexible material that serve as airflow biasing structures. In the example of  FIG. 13 , opening  250  has a circular shape and there are four corresponding flexible panels in airflow biasing structures  200 , each of which covers a respective quadrant of opening  250 . More panels or fewer panels may be used to cover an opening. The use of four panels in the example of  FIG. 13  is merely illustrative. If desired, flexible airflow biasing structures may be used in connection with arrangements of the type shown in  FIGS. 7, 8, 9, 10, and 11 . 
     The illustrative airflow biasing structures  200  that are shown in  FIGS. 7, 8, 9   10   11 , may be used with speakers that are moved to help promote cooling of power supplies and other components in device  10  and may be used while speakers are moved in tandem and/or are controlled based on analysis of upcoming audio content as described in connection with  FIGS. 1, 2, 3, 4, 5, and 6 . 
     The foregoing is merely illustrative and various modifications can be made by those skilled in the art without departing from the scope and spirit of the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20150522
Publication Date: 20180807
Grant Date: 20180807
Priority Date: 20140930
Inventors: BOOZER, BRAD G.
STANLEY, CRAIG M.
BAKER, JOHN J.
HOBSON, PHILLIP MICHAEL
BOSSCHER, NATHAN P.
Assignee: APPLE INC
CPC Classifications: [{"code": "H04R9/022", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R3/007", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K7/20145", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R7/12", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/2826", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R3/007", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K7/20145", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R2201/028", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R3/007", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R7/12", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R9/022", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/2826", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 63014054