Electronic device having antenna on grounded speaker box

An electronic device may be provided with a housing in which electrical components are mounted. The housing may include a metal portion that serves as ground. An antenna for the electronic device may be formed from metal traces on an antenna support such as a flexible printed circuit. The flexible printed circuit may be mounted to a speaker box. The speaker box may have one or more walls formed from metal plates. A metal plate in a speaker box may be coupled to a metal clip. The metal clip may be shorted to a metal stiffener that overlaps a tail portion of the flexible printed circuit. The metal stiffener may have an opening that is aligned with an opening in the metal clip. A metal fastener such as a screw may pass through the openings to short the metal clip, stiffener, and metal plate to ground.

BACKGROUND

This relates generally to electronic devices and, more particularly, to electronic devices with wireless communications circuitry.

Electronic devices often include wireless circuitry with antennas. For example, cellular telephones, computers, and other devices often contain antennas for supporting wireless communications.

It can be challenging to form electronic device antenna structures with desired attributes. In some wireless devices, the presence of conductive structures such as conductive housing structures and conductive components can influence antenna performance. Antenna performance may not be satisfactory if the housing structures are not configured properly and interfere with antenna operation or if antennas are undesirably influenced due to conductive structures in nearby components. Device size can also affect performance. It can be difficult to achieve desired performance levels in a compact device, particularly when the compact device has conductive components and housing structures.

It would therefore be desirable to be able to provide improved wireless circuitry for electronic devices such as electronic devices that include conductive structures.

SUMMARY

An electronic device may be provided with a housing in which electrical components are mounted. The housing may include a metal portion that serves as ground.

An antenna for the electronic device may be formed from metal traces on an antenna support such as a flexible printed circuit. The flexible printed circuit may be mounted to a speaker box under an inactive edge portion of a display.

The speaker box may have one or more walls formed from metal plates. The metal plates may have portions that are secured within molded plastic speaker box wall structures.

A metal plate in a speaker box may be coupled to a metal clip. The metal plate may be formed in a first speaker box portion and the metal clip may be formed in a second speaker box portion. The metal clip and metal plate may be welded to each other after joining the first and second speaker box portions.

The metal clip may be shorted to a metal stiffener that overlaps a tail portion of the flexible printed circuit. The metal stiffener may serve as a mechanical support for the flexible printed circuit and may form part of a signal path that helps ground the metal plate. A coaxial cable may be soldered or otherwise mounted to contact pads on the flexible printed circuit tail portion.

The metal stiffener may have an opening that is aligned with an opening in the metal clip. A metal fastener such as a screw may pass through the openings to short the metal clip, stiffener, and metal plate to ground.

DETAILED DESCRIPTION

Electronic devices such as electronic device10ofFIG. 1may be provided with wireless communications circuitry. The wireless communications circuitry may be used to support wireless communications in multiple wireless communications bands.

The wireless communications circuitry may include one more antennas. The antennas of the wireless communications circuitry can include loop antennas, inverted-F antennas, strip antennas, planar inverted-F antennas, slot antennas, hybrid antennas that include antenna structures of more than one type, or other suitable antennas.

Electronic device10may be a portable electronic device or other suitable electronic device. For example, electronic device10may 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 handheld device such as a cellular telephone, a media player, or other small portable device. Device10may also be a set-top box, a desktop computer, a display into which a computer or other processing circuitry has been integrated, a display without an integrated computer, or other suitable electronic equipment.

Device10may include a housing such as housing12. Housing12, 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 housing12may be formed from dielectric or other low-conductivity material. In other situations, housing12or at least some of the structures that make up housing12may be formed from metal elements.

Device10may, if desired, have a display such as display14. Display14may be mounted on the front face of device10. Display14may be a touch screen that incorporates capacitive touch electrodes or may be insensitive to touch. The rear face of housing12(i.e., the face of device10opposing the front face of device10) may have a planar housing wall.

Display14may include pixels formed from light-emitting diodes (LEDs), organic LEDs (OLEDs), plasma cells, electrowetting pixels, electrophoretic pixels, liquid crystal display (LCD) components, or other suitable pixel structures. A display cover layer such as a layer of clear glass or plastic may cover the surface of display14or the outermost layer of display14may be formed from a color filter layer, thin-film transistor layer, or other display layer. Buttons such as button24may pass through openings in the cover layer. The cover layer may also have other openings such as an opening for speaker port26. Housing12may have openings such as openings for audio jack port50, connector port52, and speaker port54.

Housing12may include peripheral housing structures such as structures16. Structures16may run around the periphery of device10and display14. In configurations in which device10and display14have a rectangular shape with four edges, structures16may be implemented using peripheral housing structures that have a rectangular ring shape with four corresponding edges (as an example). Peripheral structures16or part of peripheral structures16may serve as a bezel for display14(e.g., a cosmetic trim that surrounds all four sides of display14and/or that helps hold display14to device10). Peripheral structures16may also, if desired, form sidewall structures for device10(e.g., by forming a metal band with vertical sidewalls, curved sidewalls, etc.). Peripheral housing structures16may be formed from metal such as stainless steel, aluminum, or other suitable materials and may form antenna ground structures, portions of antenna resonating elements (e.g., inverted-F antennas and other antennas for cellular telephone communications, etc.). Other conductive housing structures (e.g., a planar rear wall for device housing12) may also be formed from metal such as stainless steel, aluminum, or other suitable materials and may form ground structures (e.g., antenna ground).

Display14may have an array of pixels that form an active area that displays images for a user of device10. An inactive border region may run along one or more of the peripheral edges of the active area. Display14may include conductive structures such as an array of capacitive electrodes for a touch sensor, conductive lines for addressing pixels, driver circuits, etc. Housing12may include internal conductive structures such as metal frame members and a planar conductive housing member (sometimes referred to as a midplate) that spans the walls of housing12(i.e., a substantially rectangular sheet formed from one or more parts that is welded or otherwise connected between opposing sides of member16). Device10may also include conductive structures such as printed circuit boards, components mounted on printed circuit boards, and other internal conductive structures. These conductive structures, which may be used in forming a ground in device10, may be located in the center of housing12and may extend under the central active area of display14.

In inactive display regions22and20, openings may be formed within the conductive structures of device10(e.g., between peripheral conductive housing structures16and opposing conductive ground structures such as conductive housing midplate or rear housing wall structures, a printed circuit board, and conductive electrical components in display14and device10). These openings may be filled with air, plastic, and other dielectrics and may be used in forming antenna resonating elements for one or more antennas in device10.

If desired, antenna traces on a flexible printed circuit or other carrier may be used to form antenna resonating elements (e.g., resonating elements for a monopole antenna, inverted-F antenna, etc.). A flexible printed circuit may have a flexible substrate formed from a layer of polyimide or other flexible sheet(s) of polymer. The flexible printed circuit on which the antenna resonating element has been formed may be mounted in a location in device10that allows the antenna to transmit and receive wireless signals. With one suitable arrangement, one or more wireless local area network antennas may be formed from flexible printed circuit(s) mounted under one or more portions of the display cover layer for display14in inactive areas of display14such as areas20and/or22. During operation, these antennas may transmit and receive antenna signals that have passed through dielectric portions of device10such as the overlapping portions of the display cover layer. If desired, housing12may be formed from dielectric and/or may be formed from metal with dielectric antenna windows located over the antennas to permit antenna signals to be transmitted and received by the antennas through the housing.

In general, device10may include any suitable number of antennas (e.g., one or more, two or more, three or more, four or more, etc.). The antennas in device10may be located at opposing first and second ends of an elongated device housing (e.g., at ends20and22of device10ofFIG. 1), along one or more edges of a device housing, in the center of a device housing, in other suitable locations, or in one or more of these locations.

In a typical scenario, device10may have one or more upper and one or more lower antennas (as an example). An upper antenna may, for example, be formed at the upper end of device10in region22. A lower antenna may, for example, be formed at the lower end of device10in region20. The antennas may be used separately to cover identical communications bands, overlapping communications bands, or separate communications bands. The antennas may be used to implement an antenna diversity scheme or a multiple-input-multiple-output (MIMO) antenna scheme (e.g., a wireless local area network MIMO scheme).

Antennas in device10may be used to support any communications bands of interest. For example, device10may include antenna structures for supporting local area network communications, voice and data cellular telephone communications, global positioning system (GPS) communications or other satellite navigation system communications, Bluetooth® communications, etc.

A schematic diagram of device10is shown inFIG. 2. As shown inFIG. 2, transceiver circuitry90in wireless circuitry34may be coupled to antenna structures such as antenna40using paths such as path92. Wireless circuitry34may be coupled to control circuitry28. Control circuitry28may be storage and processing circuitry that includes 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 circuitry28may be used to control the operation of device10. This processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, application specific integrated circuits, etc.

Control circuitry28may be used to run software on device10, 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, circuitry28may be used in implementing communications protocols. Communications protocols that may be implemented using storage and processing circuitry28include 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, multiple-input and multiple-output (MIMO) protocols, antenna diversity protocols, etc.

Control circuitry28may be coupled to input-output devices32. Input-output devices32may be used to allow data to be supplied to device10and to allow data to be provided from device10to external devices. Input-output devices32may include user interface devices, data port devices, and other input-output components. For example, input-output devices32may include touch screens, displays without touch sensor capabilities, buttons, joysticks, scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, buttons, speakers, status indicators, light sources, audio jacks and other audio port components, digital data port devices, light sensors, position and orientation sensors (e.g., sensors such as accelerometers, gyroscopes, and compasses), capacitance sensors, proximity sensors (e.g., capacitive proximity sensors, light-based proximity sensors, etc.), fingerprint sensors (e.g., a fingerprint sensor integrated with a button such as button24ofFIG. 1or a fingerprint sensor that takes the place of button24), etc.

To provide antenna structures such as antenna(s)40with the ability to cover communications frequencies of interest, antenna(s)40may be provided with circuitry such as filter circuitry (e.g., one or more passive filters and/or one or more tunable filter circuits). Discrete components such as capacitors, inductors, and resistors may be incorporated into the filter circuitry. Capacitive structures, inductive structures, and resistive structures may also be formed from patterned metal structures (e.g., part of an antenna). If desired, antenna(s)40may be provided with adjustable circuits to tune antennas over communications bands of interest.

Path92may include one or more transmission lines. As an example, signal path92ofFIG. 2may be a transmission line having a positive signal conductor such as line94and a ground signal conductor such as line96. Lines94and96may form parts of a coaxial cable or a microstrip transmission line (as examples). A matching network formed from components such as inductors, resistors, and capacitors may be used in matching the impedance of antenna(s)40to the impedance of transmission line92. Matching network components may be provided as discrete components (e.g., surface mount technology components) or may be formed from housing structures, printed circuit board structures, traces on plastic supports, etc. Components such as these may also be used in forming filter circuitry in antenna(s)40and may be tunable and/or fixed components.

Transmission line92may be coupled to antenna feed structures associated with antenna40. As an example, antenna40may be formed from an antenna resonating element trace on a flexible printed circuit (see, e.g., trace104ofFIG. 2). The antenna resonating element trace and an antenna ground (e.g., a ground formed from a portion of housing12, ground traces in one or more printed circuits, etc.) may be used to form an inverted-F antenna, a slot antenna, a hybrid inverted-F slot antenna or other antenna having an antenna feed with a positive antenna feed terminal such as terminal98and a ground antenna feed terminal such as ground antenna feed terminal100. Positive transmission line conductor94may be coupled to positive antenna feed terminal98and ground transmission line conductor96may be coupled to ground antenna feed terminal100. Other types of antenna feed arrangements may be used if desired. For example, antenna structures40may be fed using multiple feeds. The illustrative feeding configuration ofFIG. 2is merely illustrative.

A speaker such as speaker106ofFIG. 3may have an opening such as opening108that is aligned with speaker port54ofFIG. 1. Speaker106may have a speaker driver such as driver114that is located in interior cavity (speaker volume)116of speaker box118. Speaker box118, which may sometimes be referred to as a speaker enclosure, may have a wall such as upper wall110. An antenna support structure such as flexible printed circuit112may contain antenna traces for forming antenna40and may be mounted on upper wall110using adhesive or other suitable attachment mechanisms. Speaker106and, in particular, antenna40on speaker box118, may be installed under an inactive portion of display14(e.g., under a display cover layer region that serves as an antenna window).

Opening108in speaker box118may allow sound to pass from interior region116to the exterior of device10via speaker port54(e.g., through one or more openings in housing12). At the same time, speaker box118may serve as a support that holds flexible printed circuit112of antenna40at a desired distance in dimension Z from underlying ground structures (e.g., metal housing structures under box118, ground lines in printed circuits that are overlapped by box118, etc.). Speaker box118may have any suitable hollow shape (e.g., a spherical shape, a rectangular box shape, a shape with curved and/or flat portions, etc.). The use of a rectangular box shape for speaker box118ofFIG. 3is merely illustrative.

The walls of speaker box118may be formed from materials such as plastic and/or metal. Metal walls (e.g., walls of stainless steel, etc.) may be relatively thin for a given strength, and may therefore be used to help reduce the overall thickness of box118. The use of metal plates to form one or more of the walls of box18therefore allows the volume of interior cavity116to be increased without increasing the exterior dimensions of box118.

A cross-sectional side view of speaker box118of speaker106in an illustrative configuration in which box118has an upper metal plate and opposing lower metal plate is shown inFIG. 4. As shown inFIG. 4, metal plate120may form part or all of an upper wall for speaker box118and metal plate122may form part or all of a lower wall for speaker box118, and plastic sidewall structures128may be formed from plastic that is injection molded over the outer edges of metal plates120and122. Metal plates120and122have the potential to influence antenna operation for antenna40. To enhance antenna performance, ground paths such as paths124may be used to short (ground) plates120and122to ground126. Ground126may be associated with ground traces in a printed circuit that runs under box118, metal in housing12, or other ground structures. Paths124may be formed from ground path structures such as metal wires, traces in flexible printed circuits, metal clips (e.g., metal structures embedded in plastic portions of box118and/or coupled to metal plates120and/or122), metal stiffener structures, or other conductive structures.

A perspective view of flexible printed circuit112is shown inFIG. 5. Flexible printed circuit112may contain a patterned metal layer (e.g., a copper layer) and one or more dielectric layers (e.g., a layer of polyimide substrate, a coverlay layer that covers the metal layer, vias for routing signals to contact pads, etc.). The metal traces in printed circuit112may be patterned to form antenna resonating element104of antenna40(FIG. 2). In the example ofFIG. 5, flexible printed circuit112has a tail portion such as tail112′ that extends downwards from the top surface of box118(not shown inFIG. 5). Tail112′ is overlapped and stiffened using stiffener130. Stiffener130may be formed from a sheet of metal (e.g., a planar stamped stainless steel member or other planar metal member, etc.). Stiffener130may have openings such as screw holes132and134. Metal fasteners such as screws may pass through holes132and134and may be received within threaded openings in housing12, metal brackets and other support structures, port connectors, and other structures in device10. The metal screws may help form grounding paths such as paths124ofFIG. 4.

Stiffener130may help structurally support flexible printed circuit tail112′ and thereby facilitate attachment of coaxial cable92to the underside of tail112′.FIG. 6shows how coaxial cable92may have a ground conductor (conductor96) that is coupled to ground pad100′ of tail portion112′ of flexible printed circuit112at antenna ground feed100and may have a positive signal line conductor (conductor94) that is coupled to positive signal pad98′ of portion112′ at positive antenna feed98, thereby forming a feed for antenna40. A perspective view of the underside of flexible printed circuit112showing how stiffener130may overlap tail portion112′ and the end of coaxial cable92is shown inFIG. 7. A layer of adhesive142may be formed under flexible printed circuit112in region140to help attach flexible printed circuit112to the surface of upper wall110of speaker box118.

FIG. 8is a perspective view of an illustrative upper metal plate for speaker box118. As shown inFIG. 8, a metal structure such as clip150or other metal member may have a vertically extending portion such as portion152that is joined to portion120′ along seam154. Laser welds, solder, conductive adhesive, and/or other conductive fastening techniques may be used to electrically couple upper metal plate120to clip150at seam154. This allows clip150to serve as part of a grounding path such as grounding path124ofFIG. 4.

Clip150may have openings such as opening160to receive screws (e.g., to help mechanically and/or electrically couple clip150to housing12and/or other ground structures). The opening may pass through upper clip portion156and parallel lower clip portion158.

FIG. 9shows how speaker box118may be formed from multiple joined parts. As shown in the illustrative exploded perspective view ofFIG. 9, speaker box118has an upper portion such as speaker box portion118-1and a mating lower portion such as speaker box portion118-2. Upper portion118-1may have metal plate120embedded in injection molded plastic128. Lower portion118-2may have metal plate122and metal clip150embedded in injection molded plastic128. Speaker box118may be formed by moving portion118-1towards portion118-2to join portions118-1and118-2together. Ultrasonic welds, adhesive, fasteners, or other attachment mechanisms may be used in joining portions118-1and118-2.

With this approach, clip150is joined to plate120after upper and lower mating portions of speaker box118have been assembled. By delaying the process of joining clip150and plate120until after speaker box assembly, residual stresses that might otherwise be imparted to speaker box118from clip140and plate120may be minimized. This helps box118to maintain desired acoustic properties such as desired acoustic sealing levels.

A perspective view of speaker106is shown inFIG. 10. As shown inFIG. 10, a portion of upper surface110of speaker box118may be formed from metal plate120in molded plastic wall portions128. Stiffener130may overlap tail portion112′ of flexible printed circuit112for antenna40, thereby providing both structural support for tail portion112′ and grounding for the conductive structures of speaker box118. Opening108may be formed in a plastic end wall of plastic128or from other portions of speaker box118.

FIG. 11is a cross-sectional side view of speaker106ofFIG. 10taken along line170and viewed in direction172. As shown inFIG. 11, screw174may be received within threaded opening176in housing12, which may serve as ground126. Screw174may pass through an opening in flexible printed circuit178(e.g., a flexible printed circuit coupled to a port connector for port52and/or other grounded structures). Screw174may also pass through opening132in stiffener130, openings such as opening160in portions156and158of clip150, and an aligned opening in plastic128of box118. Ground126may be formed from ground structures in device10such as layer178(e.g., one or more flexible printed circuit layers such as a flexible printed circuit used for mounting a data port connector within device10), and/or housing12. The metal grounding path structures of clip150, stiffener130, and screw174form a grounding path to ground126. By grounding metal plate120(and, if desired metal plate122) in this way, electromagnetic noise can be suppressed and antenna performance for antenna40can be improved.