PATENT DOCUMENT

Publication Number: US-9065175-B2
Application Number: US-201213655215-A
Country: US
Kind Code: B2

Title: Antenna structures and electrical components with grounding

Abstract:
An electronic device may have a conductive housing with an antenna window. Antenna structures may be mounted adjacent to the antenna window. The antenna structures may have a dielectric carrier. Patterned metal antenna traces may be formed on the surface of the dielectric carrier. A proximity sensor may be formed from a flexible printed circuit mounted on the dielectric carrier. The flexible printed circuit may have a tail that contains a transmission line for feeding the antenna structures. The transmission line may include a positive signal conductor that is maintained at a desired distance from the conductive housing using a polymer sheet. A portion of the antenna structures may protrude between a microphone and a camera module. Plastic camera module housing structures may have an inner surface coated with a shielding metal. A U-shaped conductive fabric layer may be used as a grounding structure.

Claims:
What is claimed is: 
     
       1. Apparatus, comprising:
 a metal electronic device housing; 
 a dielectric carrier having antenna traces; 
 a flexible printed circuit that is coupled to the antenna traces at antenna feed terminals, wherein the flexible printed circuit has a protruding tail; 
 a transmission line in the tail that is coupled to the antenna feed terminals, wherein the transmission line has a signal conductor and a ground conductor; and 
 conductive structures that couple the ground conductor to the metal electronic device housing. 
 
     
     
       2. The apparatus defined in  claim 1  wherein the conductive structures include at least one screw. 
     
     
       3. The apparatus defined in  claim 1  further comprising a proximity sensor electrode in the flexible printed circuit. 
     
     
       4. The apparatus defined in  claim 3  wherein the metal electronic device housing comprises an internal metal wall and wherein a screw is used to attach the protruding tail to the internal metal wall. 
     
     
       5. The apparatus defined in  claim 4  further comprising a camera flexible printed circuit and a camera module mounted on the camera flexible printed circuit, wherein the internal metal wall has an opening through which the camera flexible printed circuit passes. 
     
     
       6. The apparatus defined in  claim 5  further comprising a microphone flexible printed circuit and a microphone mounted to the microphone flexible printed circuit, wherein the microphone flexible printed circuit passes through the opening. 
     
     
       7. The apparatus defined in  claim 6  further comprising a grounding structure that electrically couples the camera flexible printed circuit to the microphone flexible printed circuit. 
     
     
       8. The apparatus defined in  claim 7  wherein the grounding structure comprises conductive fabric. 
     
     
       9. The apparatus defined in  claim 1  further comprising a plurality of flexible printed circuits and a conductive fabric grounding structure that electrically couples the flexible printed circuits. 
     
     
       10. The apparatus defined in  claim 9  wherein the conductive fabric grounding structure comprises a layer of conductive fabric that is bent around a bend axis into a U-shape. 
     
     
       11. The apparatus defined in  claim 1 , further comprising:
 radio-frequency transceiver circuitry; and 
 an additional transmission line structure coupled to the transmission line in the protruding tail, wherein the additional transmission line structure is configured to convey radio-frequency signals between the radio-frequency transceiver circuitry and the transmission line in the tail. 
 
     
     
       12. The apparatus defined in  claim 1 , wherein the signal conductor of the transmission line in the protruding tail is interposed between the ground conductor of the transmission line in the protruding tail and the metal electronic device housing. 
     
     
       13. The apparatus defined in  claim 12 , further comprising first and second screws that attach the protruding tail portion to the metal electronic device housing. 
     
     
       14. The apparatus defined in  claim 13 , wherein the first and second screws electrically couple the ground conductor to the metal electronic device housing and wherein the first and second screws are formed on opposing sides of the signal conductor. 
     
     
       15. The apparatus defined in  claim 14 , wherein the protruding tail portion of the flexible printed circuit comprises a dielectric substrate, the signal conductor and the ground conductor are formed in the dielectric substrate, the first screw is formed within a first via in the dielectric substrate and the second screw is formed within a second via in the dielectric substrate, the apparatus further comprising conductive contact pads and conductive foam interposed between the dielectric substrate and the metal electronic device housing. 
     
     
       16. An electronic device, comprising:
 a metal housing; 
 a dielectric antenna window mounted within the metal housing; 
 an antenna carrier adjacent to the dielectric antenna window; 
 antenna traces on the antenna carrier; 
 a proximity sensor formed from at least one proximity sensor electrode that overlaps at least some of the antenna traces, wherein the proximity sensor electrode includes metal traces on a flexible printed circuit; and 
 a transmission line that is coupled to the antenna traces, wherein the transmission line includes a positive signal conductor and a ground signal conductor in the flexible printed circuit and wherein the ground signal conductor is shorted to the metal housing. 
 
     
     
       17. The electronic device defined in  claim 16  wherein the metal housing has an opening, the electronic device further comprising conductive fabric grounding structures adjacent the opening. 
     
     
       18. The electronic device defined in  claim 17  wherein the conductive fabric grounding structures include a U-shaped conductive fabric layer. 
     
     
       19. The electronic device defined in  claim 18  further comprising a polymer sheet located between the flexible printed circuit and the metal housing that places the positive signal conductor at a desired distance from the metal housing. 
     
     
       20. The electronic device defined in  claim 16 , further comprising:
 control circuitry that is configured to process proximity sensor signals received from the proximity sensor electrode to determine whether external objects are present within a vicinity of the proximity sensor electrode. 
 
     
     
       21. Apparatus, comprising:
 a metal electronic device housing; 
 a dielectric carrier having antenna traces; 
 a flexible printed circuit that is coupled to the antenna traces at antenna feed terminals, wherein the flexible printed circuit has a protruding tail; 
 a transmission line in the tail that is coupled to the antenna feed terminals, wherein the transmission line has a signal conductor and a ground conductor; and 
 conductive structures that couple the ground conductor to the metal electronic device housing, wherein the metal electronic device housing comprises an internal metal wall and the protruding tail of the flexible printed circuit is bent over the internal metal wall. 
 
     
     
       22. The apparatus defined in  claim 21 , further comprising:
 a screw that attaches the protruding tail to the internal metal wall and that is configured to electrically couple the ground conductor to the internal metal wall. 
 
     
     
       23. The apparatus defined in  claim 22 , further comprising:
 an additional screw that attaches the protruding tail to the metal electronic device housing and that electrically couples the ground conductor to the metal electronic device housing.

Description:
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 microphones, cameras, and other electronic 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. In many electronic devices, the presence of conductive structures associated with components can influence the performance of antennas. There is also a potential for antenna disruptions from electromagnetic interference when antennas and electrical components are mounted in close proximity with insufficient grounding. This further restricts potential mounting arrangements for components and antennas. 
     It would therefore be desirable to be able to provide improved grounding arrangements for electronic devices with antennas and electronic components. 
     SUMMARY 
     An electronic device may have a conductive housing with an antenna window. A display module may be mounted within the conductive housing. A display cover layer may cover the display module. The inner surface of an inactive edge region of the display cover layer may be coated with a layer of opaque masking material. Antenna structures may be mounted adjacent to the antenna window under the layer of opaque masking material on the display cover layer. 
     The antenna structures may be formed from patterned metal traces on a dielectric carrier. The patterned metal traces may form an antenna resonating element with positive and ground feed terminals. 
     A flexible printed circuit may include a transmission line with positive and ground conductors respectively coupled to the positive and ground feed terminals. A proximity sensor may be formed from capacitive electrodes within the flexible printed circuit. 
     The flexible printed circuit may have a tail that contains the transmission line. The positive conductor in the transmission line may be maintained at a desired distance from the conductive housing a polymer sheet. Conductive structures such as screws and vias and other metal structures in the flexible printed circuit may be used to short the ground conductor in the transmission line to the conductive housing. 
     A portion of the antenna structures may protrude between a microphone and a camera module. The microphone may be mounted to a microphone flexible printed circuit. The camera module may be mounted to a camera flexible printed circuit. The conductive housing may have a vertical shielding wall that is adjacent to the antenna structures. The microphone flexible printed circuit and the camera flexible printed circuit may pass through the opening. 
     The camera module may have plastic camera module housing structures. An inner surface of the plastic camera module housing structures may be coated with a layer of metal that serves as an electromagnetic signal interference shield. A U-shaped conductive fabric layer may be used as a grounding structure. The conductive fabric layer may be interposed between the camera flexible printed circuit and the microphone flexible printed circuit adjacent to the opening in the vertical shielding wall. 
     Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front perspective view of an illustrative electronic device of the type that may be provided with grounding structures for antennas and components in accordance with an embodiment of the present invention. 
         FIG. 2  is a diagram showing circuitry that may be used to operate antenna structures and proximity sensor structures in accordance with an embodiment of the present invention. 
         FIG. 3  is a top view of an end portion of an electronic device housing containing two antennas in accordance with an embodiment of the present invention. 
         FIG. 4  is a cross-sectional side view of a portion of an electronic device taken through a microphone and camera module with grounding structures in accordance with an embodiment of the present invention. 
         FIG. 5  is a cross-sectional side view of a portion of a camera module and associated flexible printed circuit structures in accordance with an embodiment of the present invention. 
         FIG. 6  is a cross-sectional side view of a portion of an electronic device showing how a U-shaped conductive fabric gasket may be used in shorting together adjacent flexible printed circuits as part of a grounding arrangement in accordance with an embodiment of the present invention. 
         FIG. 7  is a perspective view of an illustrative grounding structure of the type that may be used in an electronic device in accordance with an embodiment of the present invention. 
         FIG. 8  is a top view of an illustrative antenna having a carrier that is used in forming an antenna support and a support for a proximity sensor flexible printed circuit in accordance with an embodiment of the present invention. 
         FIG. 9  is a perspective view of a portion of an electronic device having an antenna with a grounded transmission line in accordance with an embodiment of the present invention. 
         FIG. 10  is a cross-sectional side view of a transmission line for an antenna having grounding structures in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices may be provided with antennas and electronic components such as microphones, cameras, sensors, and other electronic components. It may be desirable to mount components on flexible structures. For example, it may be desirable to mount a microphone, a camera, and other electronic components on flexible printed circuit structures. Flexible printed circuits, which are sometimes referred to as flex circuits, may include patterned metal traces on flexible substrates such as layers of polyimide or other flexible polymer sheets. Flexible printed circuits may be used in forming antennas, capacitive sensors (e.g., electrodes for a proximity sensor), assemblies that include antenna and capacitive sensor structures, other electronic device components, or combinations of these structures. 
     An illustrative electronic device in which electronic components and antenna structures may be used is shown in  FIG. 1 . Device  10  may include one or more antenna resonating elements, one or more capacitive proximity sensor structures, one or more components that include antenna structures and proximity sensor structures, microphone structures, camera structures, and other electronic components. In the illustrative configuration of  FIG. 1 , device  10  has the shape of a portable device such as a cellular telephone or other handheld device, tablet computer, or other portable equipment. In general, electronic devices  10  may 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. 
     As shown in  FIG. 1 , device  10  may have a display such as display  50 . Display  50  may be mounted on a front (top) surface of device  10  or may be mounted elsewhere in device  10 . Device  10  may have a housing such as housing  12 . Housing  12  may have curved portions that form the edges of device  10  and a relatively planar portion that forms the rear surface of device  10  (as an example). Housing  12  may also have other shapes, if desired. 
     Housing  12  may 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. A radio-frequency (RF) window (sometimes referred to as an antenna window) such as antenna window  58  may be formed in housing  12  (e.g., in a configuration in which the rest of housing  12  is formed from conductive structures). Window  58  may be formed from plastic, glass, ceramic, or other dielectric. Antenna and proximity sensor structures for device  10  may be formed in the vicinity of window  58 , may be covered with dielectric portions of housing  12 , and/or may be mounted under dielectric structures such as portions of a display cover layer or other dielectric display structure. 
     Device  10  may have user input-output devices such as button  59 . Display  50  may be a touch screen display that is used in gathering user touch input. The surface of display  50  may be covered using a dielectric member such as a planar cover glass member or a clear layer of plastic or the outermost layer of display  50  may be formed from a portion of a color filter layer or other display layer. The central portion of display  50  (shown as region  56  in  FIG. 1 ) may be an active region that contains an array of display pixels for displaying images and that is sensitive to touch input. The peripheral portion of display  50  such as region  54  may 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 display  50  in peripheral region  54  (e.g., on the underside of the cover glass). This layer may be transparent to radio-frequency signals. The conductive touch sensor electrodes in region  56  and the conductive structures associated with the array of display pixels in region  56  may tend to block radio-frequency signals. However, radio-frequency signals may pass through the cover glass and the opaque masking layer in inactive display region  54  (as an example). Radio-frequency signals may also pass through antenna window  58  or dielectric housing walls in housing formed from dielectric material. Lower-frequency electromagnetic fields may also pass through dielectric structures such as portions of a display cover layer, window  58 , or other dielectric housing structures, so capacitance measurements for a proximity sensor may be made through these dielectric structures. 
     With one suitable arrangement, housing  12  may be formed from a metal such as aluminum. Portions of housing  12  in the vicinity of antenna window  58  may be used as antenna ground. Antenna window  58  may be formed from a dielectric material such as polycarbonate (PC), acrylonitrile butadiene styrene (ABS), a PC/ABS blend, or other plastics (as examples). Window  58  may be attached to housing  12  using adhesive, fasteners, or other suitable attachment mechanisms. To ensure that device  10  has an attractive appearance, it may be desirable to form window  58  so that the exterior surfaces of window  58  conform to the edge profile exhibited by housing  12  in other portions of device  10 . For example, if housing  12  has straight edges  12 A and a flat bottom surface, window  58  may be formed with a right-angle bend and vertical sidewalls. If housing  12  has curved edges  12 A, window  58  may have a similarly curved exterior surface along the edge of device  10 . 
     A schematic diagram of an illustrative configuration that may be used for electronic device  10  is shown in  FIG. 2 . As shown in  FIG. 2 , electronic device  10  may include control circuitry  29 . Control circuitry  29  may include storage and processing circuitry for controlling the operation of device  10 . Control circuitry  29  may, 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 circuitry  29  may 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 circuitry  29  may be used to run software on device  10 , such as operating system software and application software. Using this software, control circuitry  29  may, 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, and perform other functions related to the operation of device  10 . 
     Input-output devices  30  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Input-output circuitry  30  may include communications circuitry such as wired communications circuitry. Device  10  may also use wireless circuitry such as radio-frequency transceiver circuitry  206  and antenna structures  204  to communicate over one or more wireless communications bands. 
     Input-output devices  30  may also include input-output components with which a user can control the operation of device  10 . A user may, for example, supply commands through input-output devices  30  and may receive status information and other output from device  10  using the output resources of input-output devices  30 . 
     Input-output devices  30  may 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 device  10  is operating and providing information to a user of device  10  about the status of device  10 . Audio components in devices  30  may include speakers and tone generators for presenting sound to a user of device  10  and microphones for gathering user audio input. Devices  30  may include one or more displays such as display  50 . Displays may be used to present images for a user such as text, video, and still images. Sensors in devices  30  may include a touch sensor array that is formed as one of the layers in display  50 . During operation, user input may be gathered using buttons and other input-output components in devices  30  such 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. 
     Device  10  may include wireless communications circuitry such as radio-frequency transceiver circuitry  206 , power amplifier circuitry, low-noise input amplifiers, passive radio frequency components, one or more antennas such as antenna structures  204 , 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 device  10  may include transceiver circuitry  206  for 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 circuitry  206  may handle 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communications and may handle the 2.4 GHz Bluetooth® communications band. Circuitry  206  may 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 device  10  can include circuitry for other short-range and long-range wireless links if desired. For example, wireless communications circuitry in device  10  may 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 structures  204  may include one or more antennas. Antenna structures  204  may 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, device  10  may include one or more antennas such as dual band inverted-F antennas formed from metal structures supported by a dielectric carrier. 
     To provide antenna structures  204  with the ability to cover communications frequencies of interest, antenna structures  204  may be provided with tunable circuitry  208 . Tunable circuitry  208  may be controlled by control signals from control circuitry  29 . For example, control circuitry  29  may supply control signals to tunable circuitry  208  using control path  210  whenever it is desired to tune antenna structures  204  to cover a desired communications band during operation of device  10 . Path  222  may be used to convey data between control circuitry  29  and radio-frequency transceiver circuitry  206  (e.g., when transmitting wireless data or when receiving and processing wireless data). 
     Transceiver circuitry  206  may be coupled to antenna structures  204  by signal paths such as signal path  212 . Signal path  212  may include one or more transmission lines. As an example, signal path  212  of  FIG. 2  may be a transmission line having a positive signal conductor such as line  214  and a ground signal conductor such as line  216 . Lines  214  and  216  may form parts of a coaxial cable, parts of a microstrip transmission line, or parts of other transmission line structures. The impedance of transmission line  212  may be 50 ohms (as an example). A matching network formed from components such as inductors, resistors, and capacitors may be used in matching the impedance of antenna structures  204  to the impedance of transmission line  212 . 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 line  212  may be coupled to antenna feed structures associated with antenna structures  204 . As an example, antenna structures  204  may include an inverted-F antenna having an antenna feed with a positive antenna feed terminal such as terminal  218  and a ground antenna feed terminal such as ground antenna feed terminal  220 . Positive transmission line conductor  214  may be coupled to positive antenna feed terminal  218  and ground transmission line conductor  216  may be coupled to ground antenna feed terminal  220 . Other types of antenna feed arrangements may be used if desired. The illustrative feeding configuration of  FIG. 2  is merely illustrative. 
     Filter circuitry such as direct current (DC) blocking capacitors  224  may, if desired, be interposed within paths  214  and  216 . Capacitors  224  may help prevent signals at low frequencies (e.g., frequencies below the lowest frequencies used by antenna structures  204  in transmitting and receiving wireless data) from reaching transceiver circuitry  206  and potentially interfering with the operation of radio-frequency transceiver circuitry  206 . 
     Tunable circuitry  208  may be formed from one or more tunable circuits such as circuits based on capacitors, resistors, inductors, and switches. Tunable circuitry  208  may be implemented using discrete components mounted to a substrate such as a rigid printed circuit board (e.g., a printed circuit board formed from glass-filled epoxy), a flexible printed circuit formed from a sheet of polyimide or a layer of other flexible polymer, a plastic carrier, a glass carrier, a ceramic carrier, or other dielectric support. With one suitable arrangement, tunable circuitry  208  may include an inductor-based tunable component (e.g., a component having one or more inductors in parallel and a switch that can be configured to selectively switch one or more of the inductors into use). An inductor-based tunable component of this type (e.g., a switchable inductor component) may be coupled between one or more of the arms in a dual arm inverted-F antenna and a ground plane or may otherwise be used in tuning the performance of antenna structures  204 . 
     As shown in  FIG. 2 , device  10  may include a proximity sensor that includes proximity sensor electrode structures  226 . Proximity sensor electrode structures  226  may include one or more or two or more layers of metal electrodes for sensing capacitance changes in the surroundings of device  10 . If desired, proximity sensor electrode structures  226  may be formed from metal traces on a flexible printed circuit or other dielectric carrier. The flexible printed circuit may be mounted within device  10  so as to surround or at least partly overlap antenna structures  204 , as shown in  FIG. 2 . With this type of arrangement, proximity sensor electrode structures  226  and antenna structures  204  may experience similar environments. This allows the proximity sensor to monitor the vicinity of antenna structures  204  for external objects such as part of a user&#39;s body. Proximity sensor signals that indicate that the user&#39;s body is present in the vicinity of antenna structures  204  may then be used to limit transmitted radio-frequency signal power from radio-frequency transceiver circuitry  206  to ensure that device  10  satisfies regulatory limits on transmitted wireless signal powers. 
     Proximity sensor circuitry  230  may be coupled to proximity sensor electrode  226  by path  228 . Inductors  229  or other filter circuitry for blocking high-frequency signals may be interposed in path  228 . The presence of high-frequency signal blocking circuitry in path  228  may help prevent radio-frequency antenna signals that are associated with antenna structures  204  from being conveyed to proximity sensor circuitry  230 . Proximity sensor circuitry  228  can receive proximity sensor signals (e.g., lower frequency signals) from electrode structures  226  through inductors  229  and can determine whether or not external objects are present in the vicinity of structures  226  based on these proximity sensor signals. For example, if a user places a body part in the vicinity of proximity sensor electrode  226 , the capacitance of sensor electrode  226  may vary and, by monitoring these capacitance fluctuations, circuitry  230  can detect the presence of the body part. 
       FIG. 3  is a top view of an end portion of device  10  of  FIG. 1 . In the illustrative configuration of  FIG. 3 , device  10  includes at least two antennas such as first antenna  204 A and second antenna  204 B. Antennas  204 A and  204 B may be, for example, inverted-F antennas that are used in handling cellular telephone communications. This is, however, merely illustrative. Antennas  204 A and  204 B may, in general, be configured to handle communications in any communications bands of interest and may use any suitable type of antenna resonating element structure. Additional antennas may be included in device  10 , if desired. For example, wireless local area network antennas may be located at an opposing end of device  10 . 
     In a configuration of the type shown in  FIG. 3  in which there are at least two antennas in device  10 , the two antennas may be used as part of a multiple input multiple output (MIMO) antenna scheme or may be used as part of an antenna diversity arrangement in which control circuitry  29  ( FIG. 2 ) switches one of the two antennas into use in real time depending on signal quality criteria or other suitable switching criteria. Antennas in device  10  may be fixed and/or tunable. For example, antenna  204 B may be a fixed primary antenna that is used for transmitting and receiving wireless signals, whereas antenna  204 A may be a tunable secondary antenna that is used exclusively or primarily for receiving wireless signals. 
     Proximity sensor structures such as proximity sensor electrode structures  226  of  FIG. 2  may be implemented using a flexible printed circuit such as flexible printed circuit  242 . Flexible printed circuit  242  may include metal traces for implementing transmission line  212  of  FIG. 2 , traces for mounting components such as filter capacitors  224  and filter inductors  229 , metal structures for coupling transmission line  212  to antenna terminals  218  and  220  of  FIG. 2 , and other conductive structures. Conductive metal traces or other conductive structures for forming antenna structures  204 B may be formed on the surface of a dielectric carrier or on a printed circuit. In a configuration in which patterned metal antenna traces are formed on the surface of a carrier, the carrier may, for example, be a plastic carrier having a protruding portion such as portion  232  of  FIG. 3 . 
     Tail portions  244  and  246  of flexible printed circuit  242  may extend over housing structures such as housing wall structures  12 W of housing  12 . The presence of tail portions  244  and  246  helps accommodate movement of antenna structures coupled to flexible printed circuit  242  relative to housing  12 . Housing wall structures  12 W may be a metal wall that extends vertically (out of the page in the orientation of  FIG. 3 ) from the rear surface of housing  12 . Housing wall structures  12 W may be interposed between antenna structures  204 A and  204 B and device circuitry located in interior portion  292  of device  10  and may therefore serve as a part of an electromagnetic interference shield. 
     Device  10  may include components such as microphone  234  and camera  236 . In region  250 , microphone  234  may be mounted on a flexible printed circuit (sometimes referred to as a microphone flexible printed circuit) and camera  236  may be mounted on a flexible printed circuit (sometimes referred to as a camera flexible printed circuit). The microphone and camera flexible printed circuits may run along the inner surface of antenna window  58  and through an opening in portion  248  of inner housing wall  12 W (e.g., a mousehole opening). 
     A cross-sectional side view of microphone  234  and camera  236  in device  10  taken along line  238  and viewed in direction  240  is shown in  FIG. 4 . As shown in  FIG. 4 , device  10  may have a display cover layer such as display cover layer  254 . Display module  252  may be mounted in active region  56  of display  50  for producing images for user of device  10 . In inactive region  54 , a layer of opaque masking material such as opaque masking layer  258  may be formed on the underside of display cover layer  254  to hide internal components from view. Camera  236  (sometimes referred to as a camera module) may be mounted under opening  274  in opaque masking layer  258  using mounting structures such as mounting ring  276 . During operation of camera  236 , image light  272  may be received through opening  274 . Optical structures such as lenses  270  may focus incoming light  272  onto digital image sensor  268  (e.g., a digital imaging sensor implemented on an integrated circuit). 
     Camera module  236  may be provided with camera housing walls such as walls  264 . Housing structures such as walls  264  may be formed from one or more structures. For example, housing walls  264  may be formed from molded and/or machined plastic parts. To help electrically isolate internal portions of camera  236  such as image sensor  268  from antenna structures in device  10  such as antenna structures  204  of  FIG. 4 , camera module  236  may be provided with shielding structures. The shielding structures may be formed form a metal coating on the inside or outside surfaces of camera module  236 . 
     As an example, metal coating  266  may be formed on the inner surfaces of plastic walls  264  of camera module  264 . Metal coating  266  may be formed by physical vapor deposition techniques, electroplating, or other suitable fabrication techniques. Portions  278  of metal coating layer  266  may be formed on the lower surfaces of camera module housing  264  and may be electrically coupled to a substrate such as camera flexible printed circuit  262 . For example, solder, conductive adhesive, conductive tape, conductive foam, or other conductive materials may be used to short metal layer  266  of camera module  236  to ground path metal traces on camera flexible printed circuit  262 . 
     Microphone  234  may be mounted on microphone flexible printed circuit  260 . Signal lines on flexible printed circuit  260  may be used to gather microphone signals from microphone  234 . Microphone  234  may receive sound through opening  290  in antenna window  58  or other portions of the housing for device  10 . Antenna window  58  may have a curved cross-sectional shape of the type shown in  FIG. 4  and may form part of the housing of device  10 . 
     Microphone flexible printed circuit  260  and camera flexible printed circuit  262  may extend through an opening such as opening  280  in housing wall  12 W (e.g., an opening in region  248  of wall  12 W of  FIG. 3 ). Housing  12  and housing wall  12 W may be formed from a metal such as aluminum and may serve as a ground for circuitry and components in device  10 . If desired, housing wall  12 W may be a machined feature that is an integral portion of the machined metal structures used to form housing  12 . 
     To help ground structures in device  10  and thereby allow antenna structures  204 B to function satisfactorily, the structures of  FIG. 4  such as camera  236 , camera flexible printed circuit  262 , microphone  234 , and microphone flexible printed circuit  260  may be grounded to housing  12  or other suitable ground structures. Grounding structures  282  may, for example, be used to ground camera flexible printed circuit  262  to microphone flexible printed circuit  260 . 
     Grounding structures  282  may be formed from a conductive material such as a conductive fabric. Microphone flexible printed circuit  260  may be grounded to housing  12  directly or through intervening structures such as audio jack flexible printed circuit  281 . The presence of grounding structures  282  such as end portion  294  of grounding structures  282  may help reduce electromagnetic interference by helping to prevent antenna signals from antenna  204 B from entering interior portion  292  of device  10  through opening  280  and by helping to prevent interference signals from interior  292  from reaching antenna  204 B through opening  280 . In effect, portion  294  of grounding structures  282  helps seal opening  280  in metal shielding wall  12 W. 
       FIG. 5  is a cross-sectional side view of a portion of camera  236  and associated flexible printed circuit structures such as camera flexible printed circuit  262  and microphone flexible printed circuit  260 . As shown in  FIG. 5 , metal portions  278  of metal shielding coating  266  on camera module housing structures  264  may be shorted to metal traces  306  in camera flexible printed circuit  262  using conductive adhesive  308 . Metal traces  306  may be, for example, ground traces in camera flexible printed circuit  262 . 
     A biasing structure such as conductive foam  300  may be used to press camera module  236  upwards towards display cover layer  254  while compressing structures such as camera flexible printed circuit  262  and microphone flexible printed circuit  260  downwards against antenna window  58 . Conductive structures such as a sheet of stainless steel or other stiffener  302  may be provided between metal ground traces such a traces  312  in camera flexible printed circuit  262  and conductive foam  300 . Stiffener  302  may provide localized structural support for flexible printed circuit  260 . Traces  312  may be shorted to traces  306  (e.g., using vias or other paths), so that traces  312  serve as ground traces. Metal traces  304  on microphone printed circuit  260  may be shorted to the ground traces on camera flexible printed circuit  262  and therefore to shield  266  in camera module  236  through conductive foam  300 . If desired, conductive adhesive may be interposed between stiffener  302  and traces  312  and/or between stiffener  302  and conductive foam  300 . Conductive adhesive may optionally also be interposed between traces  304  and conductive foam  300 . 
       FIG. 6  is a cross-sectional side view of grounding structures  282  and associated structures in the vicinity of internal housing wall  12 W. As shown in  FIG. 6 , grounding structures  282  may have a U-shaped cross section. U-shaped grounding structures  282  may be formed from a sheet of conductive fabric that is bent around bend axis  330 . If desired, other shapes such as tube shapes, corrugated shapes formed from an undulating fabric sheet, or other configurations may be used for grounding structures  282 . 
     Conductive fabric for grounding structures  282  may be formed from metal fibers, plastic fibers coated with metal, a combination of metal and plastic fibers, or other suitable conductive fibers. Camera flexible printed circuit  262  may have ground traces that are shorted to grounding structures  282  using conductive adhesive  320 . Conductive adhesive  322  may be used to attach grounding structure  282  to ground conductive ground traces in microphone flexible printed circuit  260 . Conductive adhesive  324  may be used to short the ground traces of microphone flexible printed circuit  260  to metal ground traces in a printed circuit such as audio jack flexible printed circuit  281 . Conductive adhesive  326  may be interposed between audio jack flexible printed circuit  281  and the inner surface of metal housing  12 . Metal housing  12  may serve as ground. If desired, one or more of the conductive adhesive layers of  FIG. 6  may be omitted and/or other conductive structures (e.g., solder, conductive fabric, conductive metal tape, welds, fasteners, metal paint, etc.) may be used in electrically coupling and thereby grounding the layers of  FIG. 6 . 
       FIG. 7  is a perspective view of grounding structures  282  in an illustrative U-shaped configuration. As shown in  FIG. 7 , grounding structures  282  may be formed from a conductive fabric having conductive fibers such as fibers  332 . Structure  282  may be formed from a bent sheet of conductive fabric or conductive fabric having other suitable shapes. Openings  334  may be formed in structure  282  along bend axis  330  to facilitate bending of structure  282  around bend axis  330 . If desired, a tube or a structure with other shapes may be formed from conductive fabric having fibers  332 . The U-shaped structure of  FIG. 7  is merely illustrative. 
       FIG. 8  is a top view of antenna structures  204 B. In the illustrative configuration of  FIG. 8 , antenna structures  204 B have a dielectric carrier such as carrier  336 . Carrier  336  may be formed from plastic, glass, ceramic, printed circuit board material, or other suitable dielectric material. Patterned conductive antenna resonating element traces  338  may be formed on the surface of dielectric carrier  336  (e.g., using selective surface activation and electroplating such as used in laser direct structuring techniques). Antenna feed terminals  218  and  220  may be formed from pad-shaped structures or other structures in the patterned metal coating on carrier  336 . 
     Proximity sensor electrode structures  226  may be formed from metal traces within flexible printed circuit  340 . Tail portion  342  of flexible printed circuit  340  may contain transmission line  212  of  FIG. 2 . Vias and hot bar solder connections may be used to couple transmission line positive conductor  214  to terminal  218  in the metal traces on the surface of carrier  336  and to couple transmission line ground conductor  216  to terminal  220  in the metal traces on the surface of carrier  336 . Patterned metal traces  338  may cover some or all of the surfaces of carrier  336  to form an inverted-F antenna resonating element or an antenna resonating element of another suitable type. 
     A perspective view of antenna structures  204 B mounted in device  10  is shown in  FIG. 9 . As shown in  FIG. 9 , foam such as foam  366  may be used to bias antenna structures  204 B upwards towards display cover layer  254  ( FIG. 4 ). The biasing force produced by foam  366  may help ensure that antenna structures  204 B are placed at a well-defined location relative to the dielectric of display cover layer  254 . By placing antenna structures  204 B at this well-defined location, fluctuations in the performance of antenna structures  204 B due to placement variations within device  10  can be minimized. 
     Components  350  may be mounted on flexible printed circuit  340 . Components  350  may include capacitors such as capacitors  224  of  FIG. 2 , inductors such as inductors  229  in path  228  in  FIG. 2 , switches, inductors, capacitors, and other components that are associated with adjustable components  208  (e.g., in a scenario in which the antenna structures are tunable), matching circuit components, or other circuitry. 
     Coaxial cable  370  may be connected to transmission line conductors in flexible printed circuit tail  342  of flexible printed circuit  340  using connector  372 . Cable  370  may form part of transmission line  212  ( FIG. 2 ). The transmission line conductors within tail portion  342  of flexible printed circuit  340  may be implemented using a microstrip transmission line, a stripline transmission line, or other printed circuit transmission line structure. The ground traces in the microstrip transmission line may be shorted to housing  12  and vertical housing wall  12 W. For example, fasteners such as screws  360  or other conductive structures may be used to couple the ground traces of protruding tail portion  342  of flexible printed circuit  340  to housing  12 . 
       FIG. 10  is a cross-sectional side view of tail portion  342  of flexible printed circuit  340  taken along line  362  of  FIG. 9  and viewed in direction  364 . As shown in  FIG. 10 , transmission line  212  of  FIG. 2  may be formed from conductive structures such as positive signal conductor  406  and ground signal conductor  404 . Conductor  406  may be a metal trace that serves as positive transmission line conductor  214  of  FIG. 2 . Conductor  404  may be a metal trace that serves as ground transmission line conductor  216  of  FIG. 2 . Dielectric such as polymer layer  400  may serve as a substrate for flexible printed circuit  340 . Layer  400  may be formed from a material such as polyimide or other flexible printed circuit substrate material. 
     To ground traces such as trace  404  to housing structures such as metal housing structure  12 W, screws  360  may be coupled between trace  404  (and if desired, traces on the surface of substrate  400  that are coupled to trace  404 ) and housing  12 . Screws  360  may have threaded shafts with tips that screw into threaded holes in housing  12 W such as holes  420 . Vias  402  may be used to short ground conductor trace  404  to traces forming contact pads  410 . Conductive structures  412  (e.g., foam, conductive fabric, conductive adhesive, or other conductive materials) may be used to short pads  410  (and therefore ground trace  404 ) to a ground structure such as housing  12 W. 
     Dielectric member  408  may be formed from a strip of polymer such as biaxially-oriented polyethylene terephthalate or polyester films. The thickness of film  408  may be selected to establish a desired separation D between positive signal conductor trace  406  and ground structures  12 W. As an example, dielectric film  408  may have a thickness of 200 microns (or 100-300 microns or other thickness) and the distance between film  408  and conductor  406  may be 50 microns, thereby establishing a fixed separation of 250 microns between ground structures  12 W and conductor  406 . With a satisfactorily fixed and known distance D, the impedance of the transmission line that is formed using the structures of  FIG. 10  may be maintained at a desired value such as 50 ohms. 
     The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention.

Metadata:
Filing Date: 20121018
Publication Date: 20150623
Grant Date: 20150623
Priority Date: 20121018
Inventors: CORBIN SEAN S.
GILBERT TAYLOR H.
GOMEZ ANGULO RODNEY A.
JIANG YI
LENAHAN CONOR P.
LI QINGXIANG
MCCLURE STEPHEN R.
SCHLUB ROBERT W.
YARGA SALIH
ZHU JIANG
Assignee: APPLE INC
CPC Classifications: [{"code": "H04N23/57", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2201/10409", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2201/0281", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2201/0281", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01Q1/38", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/0215", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K2201/10409", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01Q1/38", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K1/0215", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04N23/57", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/189", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/189", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/189", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/0215", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K2201/0281", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04N5/2257", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/38", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2201/10409", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 50485017