Electronic device with conductive fabric shield wall

An electronic device may have a housing such as a metal housing. A display may be mounted in the metal housing. Antenna structures may be mounted in the housing under an inactive peripheral portion of the display. Integrated circuits and other electrical components may be mounted in the housing under an active central portion of the display. Shielding structures may be configured to form a wall that extends between the display and the metal housing. The shielding structures may include a sheet of conductive fabric that is shorted to the metal housing and metal chassis structures in the display. The shielding structures may also include a tube of conductive fabric that is capacitively coupled to ground traces in a touch sensor panel. The conductive fabric tube and the sheet of conductive fabric may be shorted to each other using conductive adhesive.

BACKGROUND

This relates generally to electronic devices, and, more particularly, to grounding structures for antennas and components in electronic devices.

Electronic devices such as portable computers and handheld electronic devices are often provided with wireless communications capabilities. For example, electronic devices may use long-range wireless communications circuitry to communicate using cellular telephone bands. Electronic devices may use short-range wireless communications links to handle communications with nearby equipment. Electronic devices are also often provided with electronic components such as integrated circuits and other components.

It can be difficult to incorporate antennas and electrical components successfully into an electronic device. Some electronic devices are manufactured with small form factors, so space is limited. Integrated circuits and other components can produce interference signals, which have the potential to disrupt antennas, particularly when sources of interference signals are placed in close proximity to antennas.

It would therefore be desirable to be able to provide improved arrangements for incorporating antennas and electronic components into electronic devices.

SUMMARY

An electronic device may have a housing such as a metal housing. A display may be mounted in the metal housing. Antenna structures may be mounted in the housing under an inactive peripheral portion of the display. Integrated circuits and other electrical components may be mounted in the housing under an active central portion of the display.

Shielding structures may be configured to form a wall that that separates the antenna structures under the inactive portion of the display from components such as integrated circuits under the active portion of the display. The shielding structures may extend vertically between the display and the metal housing.

The shielding structures may include a sheet of conductive fabric that is shorted to the metal housing and that is shorted to conductive components such as metal chassis structures in the display. The sheet of conductive fabric may have a planar vertical portion and bent edge portions. The shielding structures may include a tube of conductive fabric that is capacitively coupled to ground traces in a touch sensor panel. The conductive fabric tube and the sheet of conductive fabric may be shorted to each other using conductive adhesive.

DETAILED DESCRIPTION

Electronic devices may be provided with antennas for transmitting and receiving wireless radio-frequency signals. Electronic devices may also be provided with electrical components such as integrated circuits and other devices that have the potential to interfere with antenna operation. For example, an integrated circuit such as a display driver integrated circuit may produce fundamental and harmonic signals that can produce or contribute to interference that falls within a communications band of interest. Interference may be generated, for example, that falls within a wireless local area network communications band, a cellular telephone band, or other communications band being used by an electronic device.

To reduce the potentially harmful effects of undesired electromagnetic interference, an electronic device such as electronic device10ofFIG. 1may be provided with electromagnetic interference shielding structures. These structures, which may sometimes be referred to as grounding structures or shields, may help prevent interference that is produced by an aggressor such as an integrated circuit from being received by a victim such as a radio-frequency receiver.

In the illustrative configuration ofFIG. 1, device10has the shape of a portable device such as a cellular telephone or other handheld device, tablet computer, or other portable equipment. In general, electronic devices10may be desktop computers, computers integrated into computer monitors, portable computers, tablet computers, handheld devices, cellular telephones, wristwatch devices, pendant devices, other small or miniature devices, televisions, set-top boxes, or other electronic equipment.

Device10may include one or more antenna resonating elements. For example, device10may include one or more wireless local area network antennas such as IEEE 802.11 (WiFi®) antennas operating at 2.4 GHz and/or 5 GHz that are located at one end of device10such as end6and may include one or more antennas operating at cellular telephone frequencies that are located at an opposing end of device10such as end8. Antennas may also be located at other positions around the periphery of device10, in the center of device10, or in other suitable locations.

As shown inFIG. 1, device10may have a display such as display14. Display14may be mounted on a front (top) surface of device10or may be mounted elsewhere in device10. Device10may have a housing such as housing12. Housing12may have strait walls or curved portions that form the edges of device10and a relatively planar portion that forms the rear surface of device10(as an example). Housing12may also have other shapes, if desired.

Housing12may be formed from conductive materials such as metal (e.g., aluminum, stainless steel, etc.), carbon-fiber composite material or other fiber-based composites, glass, ceramic, plastic, other materials, or combinations of these materials. Antennas may be mounted under a radio-transparent portion of display14, adjacent to a radio-transparent dielectric antenna window in a metal housing, or adjacent to a dielectric housing. Antenna window structures may be formed from plastic, glass, ceramic, or other dielectric materials.

Device10may have user input-output devices such as button16. Display14may be a touch screen display that is used in gathering user touch input. The surface of display14may be covered using a display cover layer such as a planar cover glass member or a clear layer of plastic or other dielectric member. If desired, the outermost layer of display14may be formed from a portion of a color filter layer or other display layer. The central portion of display14(shown as region20inFIG. 1) may be an active region that contains an array of display pixels for displaying images and that contains a touch sensor array that is sensitive to touch input. The peripheral portion of display14such as region22may be an inactive region that is free from touch sensor electrodes and display pixels and that does not display images.

A layer of opaque masking material such as opaque ink or plastic may be placed on the underside of display14in peripheral region22(e.g., on the underside of the cover glass or other display cover layer). The opaque masking material layer may be transparent to radio-frequency signals. The conductive touch sensor electrodes in region20and the conductive structures associated with the array of display pixels in region20may tend to block radio-frequency signals. However, radio-frequency signals may pass through the display cover layer and the opaque masking layer in inactive display region22. Antenna structures may therefore transmit and receive antenna signal through inactive display region22.

For example, antennas such as antenna24A and24B ofFIG. 1may transmit and receive radio-frequency wireless signals through inactive border region22of display14at end6of housing12. Antennas24A and24B may be, for example, wireless local area network (WLAN) antennas such as IEEE 802.11 (WiFi®) antennas. There may be any suitable number of wireless local area network antennas in device10. The configuration ofFIG. 1in which there are two antennas at end6of housing12is merely illustrative.

With one suitable arrangement, housing12may be formed from a metal such as aluminum. In this type of configuration, radio-frequency antenna signals for antennas24A and24B may pass primarily or exclusively through inactive portion22of display14at end6. If desired, portions of housing12may be formed from dielectric in the vicinity of antennas24A and24B or housing12may be formed entirely from dielectric. Examples of dielectric materials of the type that may be used in forming housing12or an antenna window in a metal housing include polycarbonate (PC), acrylonitrile butadiene styrene (ABS), PC/ABS blends, and other plastics (as examples).

A schematic diagram of an illustrative configuration that may be used for electronic device10is shown inFIG. 2. As shown inFIG. 2, electronic device10may include control circuitry36. Control circuitry36may include storage and processing circuitry for controlling the operation of device10. Control circuitry36may, for example, 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. Control circuitry36may include processing circuitry based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio codec chips, application specific integrated circuits, etc.

Control circuitry36may be used to run software on device10, such as operating system software and application software. Using this software, control circuitry36may, for example, transmit and receive wireless data, tune antennas to cover communications bands of interest, process proximity sensor signals, adjust radio-frequency transmit powers based on proximity sensor data, control which antennas are active to enhance wireless performance in real time, and may perform other functions related to the operation of device10.

Input-output devices38may be used to allow data to be supplied to device10and to allow data to be provided from device10to external devices. Input-output devices38may include communications circuitry such as wired communications circuitry. Device10may also use wireless circuitry such as radio-frequency transceiver circuitry32and antenna structures24to communicate over one or more wireless communications bands.

Input-output devices38may also include input-output components with which a user can control the operation of device10. A user may, for example, supply commands through input-output devices38and may receive status information and other output from device10using the output resources of input-output devices38.

Input-output devices38may include sensors and status indicators such as an ambient light sensor, a proximity sensor, a temperature sensor, a pressure sensor, a magnetic sensor, an accelerometer, and light-emitting diodes and other components for gathering information about the environment in which device10is operating and providing information to a user of device10about the status of device10. Audio components in devices38may include speakers and tone generators for presenting sound to a user of device10and microphones for gathering user audio input. Devices38may include one or more displays such as display14. Displays may be used to present images for a user such as text, video, and still images. Sensors in devices38may include a touch sensor array that is formed as one of the layers in display14(i.e., display14may be a touch screen display that includes a touch panel having an array of capacitive touch sensor electrodes or other touch sensors such as resistive touch sensors, light-based touch sensors, acoustic touch sensors, or force-sensor-based touch sensors). During operation, user input may be gathered using buttons and other input-output components in devices38such as touch pad sensors, buttons, joysticks, click wheels, scrolling wheels, touch sensors such as a touch sensor array in a touch screen display or a touch pad, key pads, keyboards, vibrators, cameras, and other input-output components.

Device10may include wireless communications circuitry such as radio-frequency transceiver circuitry32, power amplifier circuitry, low-noise input amplifiers, passive radio frequency components, one or more antennas such as antenna structures24, and other circuitry for handling radio frequency wireless signals. The wireless communications circuitry may include radio-frequency transceiver circuits for handling multiple radio-frequency communications bands. For example, wireless communications circuitry in device10may include transceiver circuitry32for handling cellular telephone communications, wireless local area network signals, and satellite navigation system signals such as signals at 1575 MHz from satellites associated with the Global Positioning System. Transceiver circuitry32may handle 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communications and may handle the 2.4 GHz Bluetooth® communications band. Circuitry32may use cellular telephone transceiver circuitry for handling wireless communications in cellular telephone bands such as the bands in the range of 700 MHz to 2.7 GHz (as examples).

The wireless communications circuitry in device10can include circuitry for other short-range and long-range wireless links if desired. For example, wireless communications circuitry in device10may include wireless circuitry for receiving radio and television signals, paging circuits, etc. 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.

Antenna structures24may include one or more antennas such as antennas24A and24B. Antenna structures24may include inverted-F antennas, patch antennas, loop antennas, monopoles, dipoles, single-band antennas, dual-band antennas, antennas that cover more than two bands, or other suitable antennas. As an example, device10may include one or more antennas such as single band or dual band inverted-F antennas formed from metal structures. Metal structures for forming antenna resonating elements for antenna structures24may include metal traces formed directly on a plastic carrier or other dielectric carrier or may include metal traces formed on a printed circuit. Printed circuit substrates having metal antenna traces may be supported by a plastic carrier or other dielectric carrier.

To provide antenna structures24with the ability to cover communications frequencies of interest, antenna structures24may be provided with tunable circuitry. Antenna structures24may also include antennas that are not tuned during operation. For example, antennas24A and24B may be wireless local area network antennas that cover 2.4 GHz and 5 GHz bands without using antenna tuning circuitry.

During operation, path34may be used to convey data between control circuitry36and radio-frequency transceiver circuitry32(e.g., when transmitting wireless data or when receiving and processing wireless data).

Transceiver circuitry32may be coupled to antenna structures24by signal paths such as signal paths30A and30B. Signal paths30A and30B may each include one or more transmission lines. Signal path30A may be a transmission line including positive signal path28A and ground signal path26A. Signal path30B may be a transmission line including positive signal path228B and ground signal path26B.

Transmission line paths30A and30B may form parts of a coaxial cable, parts of a microstrip transmission line, or parts of other transmission line structures. The impedance of transmission lines30A and30B may be 50 ohms (as an example). Matching network circuits formed from components such as inductors, resistors, and capacitors may be used in matching the impedance of antenna structures24to the impedances of transmission lines30A and30B. 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.

Transmission line30A may be coupled to antenna feed structures associated with antenna24A and transmission line30B may be coupled to antenna feed structures associated with antenna24B. As an example, antenna structures24A and24B may each include an inverted-F antenna having an antenna feed with a positive antenna feed terminal (+) and a ground antenna feed terminal (−). Other types of antenna feed arrangements may be used if desired. The illustrative feeding configuration ofFIG. 2is merely illustrative.

To help electromagnetically isolate antenna structures24from other components in device, one or more electromagnetic interference shielding structures may be provided in device10such as shielding structures42. Structures42may be formed from metal housing structures, conductive portions of a display or other components, metal tape or other flexible metal structures, sheet metal structures, or other conductive structures. As an example, conductive structures formed from conductive fabric may be used in forming shielding structures42. Shielding structures42may be coupled to a metal housing or other conductive structure within device10that serves as a source of ground potential (e.g., a metal structure such as metal housing12may serve as ground) and may therefore sometimes be referred to as grounding structures. Shielding structures42may help prevent undesired electromagnetic interference. As an example, shielding structures42may help prevent radio-frequency interference signals that are generated by circuitry36or38from being received by antennas24A and24B and thereby passed to circuitry32.

FIG. 3is a top view of an end portion of device10ofFIG. 1showing how shielding structures42may be interposed between central interior portion48of housing12in device10and end interior portion50of housing12at end6of device10. Interior portion48may include components such as components44. Components44may include circuitry of the type show inFIG. 2(e.g., one or more integrated circuits such as memory and processor circuits, display driver integrated circuits, etc.). Components44may be mounted on one or more substrates such as substrate46. Substrate46may be a rigid printed circuit board (e.g., a fiberglass-filled epoxy board), a flexible printed circuit (e.g., a printed circuit having a flexible printed circuit substrate such as a layer of polyimide or a sheet of other flexible polymer), a plastic carrier, or other dielectric support structure. Components such as battery structures, display and touch sensor structures, and other devices may also be mounted in region48.

Components such as button16may be mounted in region50. Antennas such as antennas24A and24B may also be mounted within region50. As shown inFIG. 3, antenna24A may have a support structure such as dielectric support structure58A. Antenna24B may have a support structure such as dielectric support structure58B. Support structures58A and58B may be formed from materials such as glass, ceramic, and plastic. As an example, support structures58A and58B may be formed from hollow or solid molded plastic parts.

Antenna24A may include flexible printed circuit60A. Flexible printed circuit60A may include a substrate and patterned metal traces such as traces62A. Metal traces62A may be patterned to form antenna structures such as an inverted-F antenna resonating element.

Antenna24B may include flexible printed circuit60B. Flexible printed circuit60B may include a flexible printed circuit substrate having patterned metal traces62B. Metal traces62B may be patterned to form antenna structures such as an inverted-F antenna resonating element.

Flexible printed circuits60A and60B may be mounted to support structures58A and58B using foam, adhesive, or other mounting structures.

During operation, the presence of shielding structures42may prevent interference signals from components44in region48from being received by antennas24A and24B and may help block antenna signals from antennas24A and24B that might otherwise pass into region48.

A cross-sectional side view of device10at an end such as end6ofFIG. 3is shown inFIG. 4. In the example ofFIG. 4, a flexible printed circuit such as flexible printed circuit60(e.g., flexible printed circuit60A or60B ofFIG. 3) is being supported by dielectric carrier58(e.g., carrier58A or carrier58B ofFIG. 3). Antenna resonating element traces for an antenna may be contained within flexible printed circuit60, as described in connection with traces62A and62B of antennas24A and24B ofFIG. 4. Display14may include a display module such as display module86and a display cover layer such as display cover layer52. Display cover layer52may be formed from a layer of clear material such as a transparent glass sheet or a transparent plastic member. Opaque masking material may be formed on the underside of display cover layer52in inactive region22of display14. In active display region20, display module86of display14may use an array of display pixels88for displaying images for a user.

To ensure consistent antenna performance from device to device, a biasing structure such as foam layer56may be interposed between antenna resonating element flexible printed circuits such as flexible printed circuit60and dielectric carriers such as dielectric carrier58. A foam layer such as foam layer56may press antenna resonating element flexible printed circuit60upwards into a known position relative to display cover layer52, thereby helping to ensure mounting consistency and reducing antenna performance fluctuations due to manufacturing variations.

Dielectric carrier58may be hollow. For example, interior portion74of dielectric carrier58may be filled with air. Components may be mounted within the interior of dielectric carrier58. For example, speaker driver76may be mounted within interior74of dielectric carrier58. During operation, speaker driver76may produce sound (i.e., cavity58may serve as a speaker box for driver76). Interior74of speaker box58may serve as speaker box cavity. Openings such as opening70in speaker box carrier58and opening72in housing12may be used to allow sound from speaker driver76to exit the interior of device10.

Portions of speaker driver76such as housing78or other structures in speaker driver76may be formed from conductive structures such as metal structures. Conductive foam82may be used to form a conductive grounding path the grounds speaker driver76to housing12. Conductive foam82may also serve as a biasing structure that helps push carrier58(and therefore flexible printed circuit antenna resonating element60upwards against the interior of display cover glass52.

Display module86may have one or more display layers. For example, display module86may have liquid crystal display layers such as a light guide plate, diffusing films, prism films, and other backlight structures, a thin-film-transistor layer, a liquid crystal layer, a color filter layer, and upper and lower polarizer layers. These layers may be assembled to from a module. The module may include plastic chassis structures (sometimes referred to as a p-chassis) and metal chassis structures (sometimes referred to as an m-chassis). Display module86may, for example, have a metal chassis such as m-chassis structure90ofFIG. 4. If desired, display module86may be formed using an array of organic light-emitting diodes or other display structures (e.g., structure for an electrophoretic display, structures for an electrowetting display, structures for a plasma display, etc.). The use of liquid crystal display pixels in forming display module86is merely illustrative.

In the illustrative configuration ofFIG. 4, display14is a touch screen display that includes touch panel96. A layer of adhesive such as adhesive layer94may be used to attach touch panel96to the underside of display cover layer52in active area20. Touch panel96may be formed from a substrate such as a layer of polyimide or other flexible polymer layer. Indium tin oxide capacitive touch sensor electrodes or other touch sensor structures may be formed on touch panel96. If desired, touch sensor structures such as an array of capacitive touch sensor electrodes may be formed directly on the underside of display cover layer52or other layers in display14. The configuration ofFIG. 4in which display14has been provided with touch sensor functionality by attaching a touch panel to the inner surface of display cover layer52is merely illustrative.

Display module86may include a rectangular array of display pixels88in the central active portion of display14. For example, in a configuration in which display module86is a liquid crystal display module, display pixels88may each include electrode structures and an associated thin-film transistor for controlling signals applied to the electrode structures. The magnitude of the signals applied to the electrode structures may be used to adjust the optical properties of the liquid crystal layer and thereby control the amount of light that is transmitted through each pixel of the display.

In general, shielding structures42may be formed from one or more pieces of conductive material. In the illustrative configuration ofFIG. 4, shielding structures42ofFIG. 3have been implemented using conductive structures such as conductive structures42A and42B. Conductive structures42A may be formed from a layer of metal tape, a thin sheet metal layer, or a layer of conductive fabric (as examples). Shielding layer portion42B may be formed from a tube of conductive fabric or other conductive material (e.g., metal tape, etc.).

As shown inFIG. 4, conductive structures42A may be formed from a sheet of material having a first planar portion such as vertical planar portion42A-1. Vertical planar portion42A-1may extend vertically between structures such as conductive housing wall12in the lower portion of device10and structures such as display14(e.g., touch panel96of display14) in the upper portion of device10. Bends may be formed in the sheet of material used to form conductive structures42A. For example, structures42A may have a lower end that is bent so that horizontal portion42A-2of structures42A extends along metal housing wall12and thereby grounds conductive structures42A to housing12. Structures42A may also have an upper end that is bent to form horizontally extending portion42A-3.

If desired, conductive adhesive may be used in coupling conductive structures42A to adjacent metal structures in device10. For example, conductive adhesive may be interposed between portion42A-2and housing wall12and/or portions42A-3and portions of display module86.

As shown inFIG. 5, horizontally extending portion42A-3of structures42A may be electrically connected to an overlapping portion of display module86such as metal chassis90. This grounds metal chassis90to housing12. An optional layer of conductive adhesive may be used in coupling portion42A-3of structures42A to metal chassis90. Conductive structures42B may be electrically grounded to housing12using structures42A. If desired, conductive adhesive such as conductive adhesive layer120may be interposed between structures42B and structures42A to help attach and short structures42B to structures42A.

Touch sensor layer96may include a touch sensor substrate layer such as substrate100. Substrate100may be formed from a layer of polyimide or other polymer. Capacitive touch sensor electrodes such as indium tin oxide electrodes or electrodes formed from other conductive transparent material may be formed on the upper and/or lower surfaces of substrate100. For example, capacitive touch sensor electrodes104may be formed on the upper surface of substrate100and capacitive touch sensor electrodes106may be formed on the lower surface of substrate100. Adhesive94may be used to attach touch sensor86to the underside of display cover layer52(FIG. 4).

Conductive structure42B may be formed from a hollow tube of conductive fabric that runs along the edge of touch sensor96(i.e., along an axis that extends into the page ofFIG. 5). Touch sensor layer96may include ground conductors such as ground traces102on substrate100. Conductive shielding structure42B may be electrically coupled to ground traces102via capacitive coupling, as illustrated schematically by capacitance110ofFIG. 5. By capacitively coupling touch sensor ground traces102conductive structures42B, traces102may be grounded to housing12through conductive structures42A, thereby shorting structures42to the top of device10(at display14). Structures42A may also be shorted to the bottom of device10at housing12, so that structures form a vertical conductive shielding wall.