PATENT DOCUMENT

Publication Number: US-9577318-B2
Application Number: US-201414463299-A
Country: US
Kind Code: B2

Title: Electronic device with fingerprint sensor and tunable hybrid antenna

Abstract:
An electronic device may have wireless circuitry and components such as sensors. The electronic device may have a metal housing having first and second planar rear wall portions separated by a gap. Conductive structures may bridge the gap to electrically couple the first and second rear wall portions. The wireless circuitry may include a hybrid slot inverted-F antenna. The antenna may have an inverted-F antenna resonating element formed from peripheral housing structures that are separated from the second rear wall portion by an opening. The opening may form a C-shaped slot antenna resonating element for the antenna. The sensors may include a fingerprint sensor. The fingerprint sensor may be coupled to a button member in a button. The fingerprint sensor and other portions of the button may overlap the second planar rear wall portion to minimize interference with antenna operation.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a housing having peripheral conductive structures; 
 a hybrid inverted-F slot antenna, wherein the hybrid inverted-F slot antenna has an inverted-F antenna portion formed from an inverted-F antenna resonating element and an antenna ground, the inverted-F antenna resonating element is formed from the peripheral conductive structures, the hybrid inverted-F slot antenna has a slot antenna portion formed from an opening between the inverted-F antenna resonating element and the antenna ground, and the antenna ground has an extended portion adjacent to the slot; 
 an antenna feed that feeds both the inverted-F antenna portion and the slot antenna portion; and 
 a fingerprint sensor overlapping the extended portion of the antenna ground. 
 
     
     
       2. The electronic device defined in  claim 1  further comprising a flexible printed circuit, wherein the fingerprint sensor is mounted to the flexible printed circuit and a portion of the flexible printed circuit on which the fingerprint sensor is mounted overlaps the extended portion of the antenna ground. 
     
     
       3. The electronic device defined in  claim 2  wherein the housing has a metal rear wall and wherein the antenna ground is formed from the metal rear wall. 
     
     
       4. The electronic device defined in  claim 3  wherein the extended portion of the antenna ground is formed from the metal rear wall. 
     
     
       5. The electronic device defined in  claim 4  further comprising:
 a button that has a switch. 
 
     
     
       6. The electronic device defined in  claim 5  wherein the button overlaps the extended portion of the antenna ground. 
     
     
       7. The electronic device defined in claim  6  wherein the fingerprint sensor is mounted within the button. 
     
     
       8. The electronic device defined in  claim 7  wherein the metal rear wall has a first planar portion and a second planar portion that are separated by a gap filled with plastic and that are electrically coupled by conductive structures, the first portion forms at least part of the antenna ground, and the second portion forms the extended portion of the antenna ground. 
     
     
       9. The electronic device defined in  claim 8  further comprising:
 a connector receptacle, wherein the button overlaps the connector receptacle. 
 
     
     
       10. The electronic device defined in  claim 9  wherein the opening is a C-shaped slot having a portion that runs along the peripheral conductive structures. 
     
     
       11. The electronic device defined in  claim 10  further comprising:
 a display having a display module that overlaps the antenna ground without overlapping the extended portion of the antenna ground and having a display cover layer that overlaps the display module and the extended portion of the antenna ground. 
 
     
     
       12. The electronic device defined in  claim 5  wherein the button comprises a dielectric button member surrounded by a metal trim. 
     
     
       13. The electronic device defined in  claim 5  further comprising a display having a display module and a display cover layer formed over the display module, wherein the display cover layer has an opening that overlaps the button. 
     
     
       14. The electronic device defined in  claim 1  wherein the slot is a C-shaped slot that runs along peripheral edges of the housing and the antenna feed has first and second feed terminals on opposing sides of the C-shaped slot. 
     
     
       15. The electronic device defined in  claim 14  further comprising:
 an inductor and a switch that are connected in series and that are coupled to the hybrid inverted-F slot antenna, wherein the switch is configured to switch the inductor into use and out of use to compensate for detuning of the antenna due to presence of an external object adjacent to the hybrid inverted-F slot antenna. 
 
     
     
       16. The electronic device defined in  claim 1  further comprising:
 a display having a display module that overlaps the antenna ground without overlapping the extended portion of the antenna ground and having a display cover layer that overlaps the display module and the extended portion of the antenna ground. 
 
     
     
       17. The electronic device defined in  claim 1  further comprising a transmission line coupled to the hybrid inverted-F slot antenna and a tunable impedance matching circuit interposed in the transmission line. 
     
     
       18. An electronic device, comprising:
 a hybrid inverted-F slot antenna having an inverted-F antenna resonating element, a slot antenna resonating element, and an antenna ground; and 
 a switch and an inductor coupled to the hybrid inverted-F slot antenna, wherein the switch is configured to switch the inductor out of use in response to detecting a user&#39;s hand adjacent to the antenna. 
 
     
     
       19. The electronic device defined in  claim 18  further comprising a fingerprint sensor that overlaps a portion of the antenna ground. 
     
     
       20. The electronic device defined in  claim 19  wherein the slot antenna resonating element is formed from a C-shaped slot that separates the inverted-F antenna resonating element from the portion of the antenna ground. 
     
     
       21. The electronic device defined in  claim 20  further comprising an adjustable inductor that is coupled across the slot antenna resonating element and that tunes a low communications band for the hybrid inverted-F slot antenna. 
     
     
       22. The electronic device defined in  claim 20 , wherein the C-shaped slot has first, second, and third portions that separate the inverted-F antenna resonating element from the portion of the antenna ground, the first portion extends substantially perpendicular from a first end of the second portion, and the third portion extends substantially perpendicular form a second end of the second portion.

Description:
BACKGROUND 
     This relates generally to electronic devices and, more particularly, to electronic devices with components such as wireless components and sensors. 
     Electronic devices often include wireless circuitry with antennas. For example, cellular telephones, computers, and other devices often contain antennas for supporting wireless communications. Sensors and other electrical components are also often included in electronic devices. 
     It can be challenging to form electronic device antenna structures with desired attributes. In some wireless devices, the presence of conductive housing structures, sensors, and other electrical components can influence antenna performance. Antenna performance may not be satisfactory if the housing structures or electrical components are not configured properly and interfere with antenna operation. 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 housing structures. 
     It would therefore be desirable to be able to provide improved wireless circuitry and electrical components for electronic devices such as electronic devices that include conductive housing structures. 
     SUMMARY 
     An electronic device may have wireless circuitry and components such as sensors. The electronic device may have a metal housing having first and second planar rear wall portions separated by a gap. Conductive structures may bridge the gap to electrically couple the first and second rear wall portions. The first rear wall portion may form an antenna ground. The second rear wall portion may form an extended portion of the antenna ground. 
     The wireless circuitry may include a hybrid inverted-F slot antenna. The antenna may have an inverted-F antenna resonating element formed from peripheral housing structures that are separated from the second rear wall portion by an opening. The opening may form a C-shaped slot antenna resonating element for the antenna. 
     The sensors may include a fingerprint sensor. The fingerprint sensor may be coupled to a button member in a button. The fingerprint sensor and other portions of the button may overlap the second planar rear wall portion to minimize interference with antenna operation. 
     An impedance matching circuit may be coupled to the antenna to match the impedance of the antenna to a transmission line. An inductor that is coupled in series with a switch may be coupled to the antenna. Antenna impedance may be measured in real time using a coupler interposed between a transceiver and the antenna. Based on antenna impedance measurements, sensor data, or other information, control circuitry can determine when an external object such as a user&#39;s hand is adjacent to the antenna. The inductor may then be switched out of use with the switch to ensure that the antenna is tuned satisfactorily. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device in accordance with an embodiment. 
         FIG. 2  is a schematic diagram of illustrative circuitry in an electronic device in accordance with an embodiment. 
         FIG. 3  is a schematic diagram of illustrative wireless circuitry in accordance with an embodiment. 
         FIG. 4  is a schematic diagram of an illustrative inverted-F antenna in accordance with an embodiment. 
         FIG. 5  is a schematic diagram of an illustrative slot antenna in accordance with an embodiment of the present invention. 
         FIG. 6  is a diagram of an illustrative hybrid inverted-F slot antenna in accordance with an embodiment. 
         FIG. 7  is a diagram of an illustrative tunable antenna circuitry in accordance with an embodiment. 
         FIG. 8  is a Smith chart illustrating how antenna tuning using a tunable impedance matching network may be used to maintain a desired level of antenna performance in the presence of contact between a user&#39;s hand and the antenna in accordance with an embodiment. 
         FIG. 9  is a diagram showing how an electrical component such as a fingerprint sensor may be located over a ground plane extension that is used in forming part of a hybrid antenna in accordance with an embodiment. 
         FIG. 10  is an interior top view of an illustrative end of an electronic device with conductive structures bridging a dielectric gap in accordance with an embodiment. 
         FIG. 11  is an exterior view of an illustrative end of an electronic device with conductive structures. 
         FIG. 12  is a cross-sectional side view of an illustrative electronic device having an electrical component such as a fingerprint sensor that overlaps a ground plane extension associated with an antenna in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices such as electronic device  10  of  FIG. 1  may be provided with electrical components and wireless communications circuitry. The wireless communications circuitry may include one or more antennas and may be used to support wireless communications in multiple wireless communications bands. An electrical component such as sensor may overlap an antenna in the wireless communications circuitry. For example, a fingerprint sensor may be mounted in a location where the fingerprint sensor overlaps an extended portion of an antenna ground plane. This location may help to minimize interference between the fingerprint sensor and antenna while allowing the fingerprint sensor to be used to capture fingerprints. 
     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. Conductive structures for the antennas may, if desired, be formed from conductive electronic device structures. The conductive electronic device structures may include conductive housing structures. The housing structures may include peripheral structures such as peripheral conductive structures that run around the periphery of an electronic device. The peripheral conductive structure may serve as a bezel for a planar structure such as a display, may serve as sidewall structures for a device housing, may have portions that extend upwards from an integral planar rear housing (e.g., to form vertical planar sidewalls or curved sidewalls), and/or may form other housing structures. Gaps may be formed in the peripheral conductive structures that divide the peripheral conductive structures into peripheral segments. One or more of the segments may be used in forming one or more antennas for electronic device  10 . Antennas may also be formed using an antenna ground plane formed from conductive housing structures such as metal housing midplate structures and other internal device structures. Rear housing wall structures may be used in forming antenna structures such as an antenna ground. 
     Electronic device  10  may be a portable electronic device or other suitable electronic device. For example, electronic device  10  may be a laptop computer, a tablet computer, a somewhat smaller device such as a wrist-watch device, pendant device, headphone device, earpiece device, or other wearable or miniature device, a handheld device such as a cellular telephone, a media player, or other small portable device. Device  10  may also be a television, a set-top box, a desktop computer, a computer monitor into which a computer has been integrated, or other suitable electronic equipment. 
     Device  10  may include a housing such as housing  12 . Housing  12 , which may sometimes be referred to as a case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of these materials. In some situations, parts of housing  12  may be formed from dielectric or other low-conductivity material. In other situations, housing  12  or at least some of the structures that make up housing  12  may be formed from metal elements. 
     Device  10  may, if desired, have a display such as display  14 . The rear face of housing  12  may have a planar housing wall. The rear housing wall may be separated into first and second portions by a gap that is filled with plastic or other dielectric. Conductive structures may electrically couple the first and second portions together. Display  14  may be mounted on the opposing front face of device  10  from the rear housing wall. Display  14  may be a touch screen that incorporates capacitive touch electrodes or may be insensitive to touch. 
     Display  14  may include image pixels formed from light-emitting diodes (LEDs), organic LEDs (OLEDs), plasma cells, electrowetting pixels, electrophoretic pixels, liquid crystal display (LCD) components, or other suitable image pixel structures. A display cover layer such as a layer of clear glass or plastic may cover the surface of display  14 . Buttons such as button  24  may pass through openings in the cover layer. The cover layer may also have other openings such as an opening for speaker port  26 . 
     Housing  12  may include peripheral housing structures such as structures  16 . Structures  16  may run around the periphery of device  10  and display  14 . In configurations in which device  10  and display  14  have a rectangular shape with four edges, structures  16  may be implemented using peripheral housing structures that have a rectangular ring shape with four corresponding edges (as an example). Peripheral structures  16  or part of peripheral structures  16  may serve as a bezel for display  14  (e.g., a cosmetic trim that surrounds all four sides of display  14  and/or that helps hold display  14  to device  10 ). Peripheral structures  16  may also, if desired, form sidewall structures for device  10  (e.g., by forming a metal band with vertical sidewalls, curved sidewalls, etc.). 
     Peripheral housing structures  16  may be formed of a conductive material such as metal and may therefore sometimes be referred to as peripheral conductive housing structures, conductive housing structures, peripheral metal structures, or a peripheral conductive housing member (as examples). Peripheral housing structures  16  may be formed from a metal such as stainless steel, aluminum, or other suitable materials. One, two, or more than two separate structures may be used in forming peripheral housing structures  16 . 
     It is not necessary for peripheral housing structures  16  to have a uniform cross-section. For example, the top portion of peripheral housing structures  16  may, if desired, have an inwardly protruding lip that helps hold display  14  in place. The bottom portion of peripheral housing structures  16  may also have an enlarged lip (e.g., in the plane of the rear surface of device  10 ). Peripheral housing structures  16  may have substantially straight vertical sidewalls, may have sidewalls that are curved, or may have other suitable shapes. In some configurations (e.g., when peripheral housing structures  16  serve as a bezel for display  14 ), peripheral housing structures  16  may run around the lip of housing  12  (i.e., peripheral housing structures  16  may cover only the edge of housing  12  that surrounds display  14  and not the rest of the sidewalls of housing  12 ). 
     If desired, housing  12  may have a conductive rear surface. For example, housing  12  may be formed from a metal such as stainless steel or aluminum. The rear surface of housing  12  may lie in a plane that is parallel to display  14 . In configurations for device  10  in which the rear surface of housing  12  is formed from metal, it may be desirable to form parts of peripheral conductive housing structures  16  as integral portions of the housing structures forming the rear surface of housing  12 . For example, a rear housing wall of device  10  may be formed from a planar metal structure and portions of peripheral housing structures  16  on the sides of housing  12  may be formed as vertically extending integral metal portions of the planar metal structure. Housing structures such as these may, if desired, be machined from a block of metal and/or may include multiple metal pieces that are assembled together to form housing  12 . The planar rear wall of housing  12  may have one or more, two or more, or three or more portions. 
     Display  14  may include conductive structures such as an array of capacitive electrodes, conductive lines for addressing pixel elements, driver circuits, etc. Housing  12  may include internal structures such as metal frame members, a planar housing member (sometimes referred to as a midplate) that spans the walls of housing  12  (i.e., a substantially rectangular sheet formed from one or more parts that is welded or otherwise connected between opposing sides of member  16 ), printed circuit boards, and other internal conductive structures. These conductive structures, which may be used in forming a ground plane in device  10 , may be located in the center of housing  12  under active area AA of display  14  (e.g., the portion of display  14  that contains a display module for displaying images). 
     In regions  22  and  20 , openings may be formed within the conductive structures of device  10  (e.g., between peripheral conductive housing structures  16  and opposing conductive ground structures such as conductive housing midplate or rear housing wall structures, a printed circuit board, and conductive electrical components in display  14  and device  10 ). These openings, which may sometimes be referred to as gaps, may be filled with air, plastic, and other dielectrics. 
     Conductive housing structures and other conductive structures in device  10  such as a midplate, traces on a printed circuit board, display  14 , and conductive electronic components may serve as a ground plane for the antennas in device  10 . The openings in regions  20  and  22  may serve as slots in open or closed slot antennas, may serve as a central dielectric region that is surrounded by a conductive path of materials in a loop antenna, may serve as a space that separates an antenna resonating element such as a strip antenna resonating element or an inverted-F antenna resonating element from the ground plane, may contribute to the performance of a parasitic antenna resonating element, or may otherwise serve as part of antenna structures formed in regions  20  and  22 . If desired, the ground plane that is under active area AA of display  14  and/or other metal structures in device  10  may have portions that extend into parts of the ends of device  10  (e.g., the ground may extend towards the dielectric-filled openings in regions  20  and  22 ). 
     In general, device  10  may include any suitable number of antennas (e.g., one or more, two or more, three or more, four or more, etc.). The antennas in device  10  may be located at opposing first and second ends of an elongated device housing (e.g., at ends  20  and  22  of device  10  of  FIG. 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. The arrangement of  FIG. 1  is merely illustrative. 
     Portions of peripheral housing structures  16  may be provided with gap structures. For example, peripheral housing structures  16  may be provided with one or more gaps such as gaps  18 , as shown in  FIG. 1 . The gaps in peripheral housing structures  16  may be filled with dielectric such as polymer, ceramic, glass, air, other dielectric materials, or combinations of these materials. Gaps  18  may divide peripheral housing structures  16  into one or more peripheral conductive segments. There may be, for example, two peripheral conductive segments in peripheral housing structures  16  (e.g., in an arrangement with two gaps), three peripheral conductive segments (e.g., in an arrangement with three gaps), four peripheral conductive segments (e.g., in an arrangement with four gaps, etc.). The segments of peripheral conductive housing structures  16  that are formed in this way may form parts of antennas in device  10 . If desired, gaps may extend across the width of the rear wall of housing  12  and may penetrate through the rear wall of housing  12  to divide the rear wall into different portions. Polymer or other dielectric may fill these housing gaps (grooves). 
     In a typical scenario, device  10  may have upper and lower antennas (as an example). An upper antenna may, for example, be formed at the upper end of device  10  in region  22 . A lower antenna may, for example, be formed at the lower end of device  10  in region  20 . 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. 
     Antennas in device  10  may be used to support any communications bands of interest. For example, device  10  may 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 showing illustrative components that may be used in device  10  of  FIG. 1  is shown in  FIG. 2 . As shown in  FIG. 2 , device  10  may include control circuitry such as storage and processing circuitry  28 . Storage and processing circuitry  28  may include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in storage and processing circuitry  28  may be used to control the operation of device  10 . This processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, application specific integrated circuits, etc. 
     Storage and processing circuitry  28  may be used to run software on device  10 , such as internet browsing applications, voice-over-internet-protocol (VOIP) telephone call applications, email applications, media playback applications, operating system functions, etc. To support interactions with external equipment, storage and processing circuitry  28  may be used in implementing communications protocols. Communications protocols that may be implemented using storage and processing circuitry  28  include internet protocols, wireless local area network protocols (e.g., IEEE 802.11 protocols—sometimes referred to as WiFi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol, cellular telephone protocols, MIMO protocols, antenna diversity protocols, etc. 
     Input-output circuitry  30  may include input-output devices  32 . Input-output devices  32  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Input-output devices  32  may include user interface devices, data port devices, and other input-output components. For example, input-output devices may 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, motion sensors (accelerometers), capacitance sensors, proximity sensors, fingerprint sensors (e.g., a fingerprint sensor integrated with a button such as button  24  of  FIG. 1 ), etc. 
     Input-output circuitry  30  may include wireless communications circuitry  34  for communicating wirelessly with external equipment. Wireless communications circuitry  34  may include radio-frequency (RF) transceiver circuitry formed from one or more integrated circuits, power amplifier circuitry, low-noise input amplifiers, passive RF components, one or more antennas, transmission lines, and other circuitry for handling RF wireless signals. Wireless signals can also be sent using light (e.g., using infrared communications). 
     Wireless communications circuitry  34  may include radio-frequency transceiver circuitry  90  for handling various radio-frequency communications bands. For example, circuitry  34  may include transceiver circuitry  36 ,  38 , and  42 . Transceiver circuitry  36  may handle 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communications and may handle the 2.4 GHz Bluetooth® communications band. Circuitry  34  may use cellular telephone transceiver circuitry  38  for handling wireless communications in frequency ranges such as a low communications band from 700 to 960 MHz, a midband from 1710 to 2170 MHz, and a high band from 2300 to 2700 MHz or other communications bands between 700 MHz and 2700 MHz or other suitable frequencies (as examples). Circuitry  38  may handle voice data and non-voice data. Wireless communications circuitry  34  can include circuitry for other short-range and long-range wireless links if desired. For example, wireless communications circuitry  34  may include 60 GHz transceiver circuitry, circuitry for receiving television and radio signals, paging system transceivers, near field communications (NFC) circuitry, etc. Wireless communications circuitry  34  may include global positioning system (GPS) receiver equipment such as GPS receiver circuitry  42  for receiving GPS signals at 1575 MHz or for handling other satellite positioning data. In WiFi® and Bluetooth® links and other short-range wireless links, wireless signals are typically used to convey data over tens or hundreds of feet. In cellular telephone links and other long-range links, wireless signals are typically used to convey data over thousands of feet or miles. 
     Wireless communications circuitry  34  may include antennas  40 . Antennas  40  may be formed using any suitable antenna types. For example, antennas  40  may include antennas with resonating elements that are formed from loop antenna structures, patch antenna structures, inverted-F antenna structures, slot antenna structures, planar inverted-F antenna structures, helical antenna structures, hybrids of these designs, etc. Different types of antennas may be used for different bands and combinations of bands. For example, one type of antenna may be used in forming a local wireless link antenna and another type of antenna may be used in forming a remote wireless link antenna. 
     As shown in  FIG. 3 , transceiver circuitry  90  in wireless circuitry  34  may be coupled to antenna structures  40  using paths such as path  92 . Wireless circuitry  34  may be coupled to control circuitry  28 . Control circuitry  28  may be coupled to input-output devices  32 . Input-output devices  32  may supply output from device  10  and may receive input from sources that are external to device  10 . 
     To provide antenna structures such as antenna(s)  40  with the ability to cover communications frequencies of interest, antenna(s)  40  may 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)  40  may be provided with adjustable circuits such as tunable components  102  to tune antennas over communications bands of interest. Tunable components  102  may be part of a tunable filter or tunable impedance matching network, may be part of an antenna resonating element, may span a gap between an antenna resonating element and antenna ground, etc. Tunable components  102  may include tunable inductors, tunable capacitors, or other tunable components. Tunable components such as these may be based on switches and networks of fixed components, distributed metal structures that produce associated distributed capacitances and inductances, variable solid state devices for producing variable capacitance and inductance values, tunable filters, or other suitable tunable structures. During operation of device  10 , control circuitry  28  may issue control signals on one or more paths such as path  93  that adjust inductance values, capacitance values, or other parameters associated with tunable components  102 , thereby tuning antenna structures  40  to cover desired communications bands. 
     Path  92  may include one or more transmission lines. As an example, signal path  92  of  FIG. 3  may be a transmission line having a positive signal conductor such as line  94  and a ground signal conductor such as line  96 . Lines  94  and  96  may 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)  40  to the impedance of transmission line  92 . 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)  40  and may be tunable and/or fixed components. 
     Transmission line  92  may be coupled to antenna feed structures associated with antenna structures  40 . As an example, antenna structures  40  may 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 terminal  98  and a ground antenna feed terminal such as ground antenna feed terminal  100 . Positive transmission line conductor  94  may be coupled to positive antenna feed terminal  98  and ground transmission line conductor  96  may be coupled to ground antenna feed terminal  92 . Other types of antenna feed arrangements may be used if desired. The illustrative feeding configuration of  FIG. 3  is merely illustrative. 
     A directional coupler such as coupler  95  may be interposed in transmission line path  92 . Control circuitry  28  and transceiver circuitry  90  may gather phase and magnitude information on the impedance of antenna  40  (or part of antenna  40 ) using directional coupler  95 . By using coupler  95  or other circuitry to gather real time information on the impedance of antenna  40 , control circuitry  28  can determine when antenna  40  is being loaded by external objects (e.g., when a user&#39;s hand is in the vicinity of antenna  40  and is therefore affecting the impedance of antenna  40 ). In response to detecting that a user&#39;s hand or other external object is adjacent to antenna  40 , control circuitry  28  may take corrective action. For example, control circuitry  28  may adjust an adjustable inductor or other tunable component  102  to ensure that antenna  40  operates as desired. If desired, control circuitry  28  may use information from a proximity sensor (see, e.g., sensors  32  of  FIG. 2 ), received signal strength information, or other information in determining when antenna  40  is being affected by the presence of nearby external objects. The use of antenna feedback from directional coupler  95  is merely illustrative. 
       FIG. 4  is a diagram of illustrative inverted-F antenna structures that may be used in implementing antenna  40  for device  10 . Inverted-F antenna  40  of  FIG. 4  has antenna resonating element  106  and antenna ground (ground plane)  104 . Antenna resonating element  106  may have a main resonating element arm such as arm  108 . The length of arm  108  and/or portions of arm  108  may be selected so that antenna  40  resonates at desired operating frequencies. For example, if the length of arm  108  may be a quarter of a wavelength at a desired operating frequency for antenna  40 . Antenna  40  may also exhibit resonances at harmonic frequencies. 
     Main resonating element arm  108  may be coupled to ground  104  by return path  110 . Antenna feed  112  may include positive antenna feed terminal  98  and ground antenna feed terminal  100  and may run in parallel to return path  110  between arm  108  and ground  104 . If desired, inverted-F antennas such as illustrative antenna  40  of  FIG. 4  may have more than one resonating arm branch (e.g., to create multiple frequency resonances to support operations in multiple communications bands) or may have other antenna structures (e.g., parasitic antenna resonating elements, tunable components to support antenna tuning, etc.). For example, arm  108  may have left and right branches that extend outwardly from feed  112  and return path  110 . 
     Antenna  40  may include a slot antenna resonating element. As shown in  FIG. 5 , for example, antenna  40  may be a slot antenna having an opening such as slot  114  that is formed within antenna ground  104 . Slot  114  may be filled with air, plastic, and/or other dielectric. The shape of slot  114  may be straight or may have one or more bends (i.e., slot  114  may have an elongated shape following a meandering path). The antenna feed for antenna  40  may include positive antenna feed terminal  98  and ground antenna feed terminal  100 . Feed terminals  98  and  100  may, for example, be located on opposing sides of slot  114  (e.g., on opposing long sides). Slot-based antenna resonating elements such as slot antenna resonating element  114  of  FIG. 5  may give rise to an antenna resonance at frequencies in which the wavelength of the antenna signals is equal to the perimeter of the slot. In narrow slots, the resonant frequency of a slot antenna resonating element is associated with signal frequencies at which the slot length is equal to a half of a wavelength. Slot antenna frequency response can be tuned using one or more tunable components such as tunable inductors or tunable capacitors. These components may have terminals that are coupled to opposing sides of the slot (i.e., the tunable components may bridge the slot). If desired, tunable components may have terminals that are coupled to respective locations along the length of one of the sides of slot  114 . Combinations of these arrangements may also be used. 
     If desired, antenna  40  may incorporate conductive device structures such as portions of housing  12 . As an example, peripheral conductive structures  16  may include multiple portions such as segments  16 B and  16 E of  FIG. 6 . Peripheral conductive structures  16 E may be conductive structures that run along the left and right edges of antenna ground plane  104  (e.g., housing sidewalls that are separate from the rear of housing  12  or that are integral portions of housing  12  that extend upwards from the rear wall of housing  12 ). Ground plane  104  may be formed by portions of a metal housing midplate member, a metal rear housing wall, conductive portions of display  14 , or other conductive antenna ground structures. Peripheral conductive structures  16 B may run along the end of device  10  (e.g., the lower peripheral edge of device  10  in the example of  FIG. 6 ) and may have shorter portions that run along sections of the left and right edges of device  10 . 
     Along the periphery of device  10 , structures  16 B and  16 E may be separated by gaps such as gaps  18 . Gaps  18  may be filled with a dielectric such as polymer. Ground plane  104  may have an extended portion such as extended portion  104 E that extends into the space between structures  16 B and the rest of ground plane  104  (i.e., the portion of the ground formed from display  14 , a metal housing midplate, and/or the central portion of the planar rear wall of housing  12 ). 
     In the example of  FIG. 6 , antenna  40  has been formed at lower end  20  of device  10 . This is merely illustrative. Antennas such as antenna  40  of  FIG. 6  may be formed at opposing ends of device  10  or different antennas may be formed at each end of device  10 . Configurations with more than two antennas for device  10  may also be used. 
     Antenna  40  may be a hybrid antenna such as a hybrid inverted-F slot antenna having both slot and inverted-F antenna portions. Ground  104  (including ground plane extension  104 E) may form an antenna ground for antenna  40 . The slot portion of antenna  40  of  FIG. 6  may be formed from slot  114  between peripheral conductive structures  16 B and ground plane extension  104 E of ground  104 . Slot  114  may have a C shape as shown in  FIG. 6  (i.e., slot  114  may be a C-shaped slot that runs along peripheral edges of device  10  and housing  12 ) or may have other slots shapes with bends. Straight slots without bends may also be used in forming antenna  40 , if desired. The inverted-F portion of antenna  40  of  FIG. 6  may be formed from an inverted-F resonating element such as peripheral conductive structures  16 B and ground  104  (ground plane extension  104 E). 
     A conductive path such as a strip of metal or metal trace on a printed circuit or plastic carrier may form return path  110  for the inverted-F portion of antenna  40 . Return path  110  may be coupled between structures  16 B and ground  104  in parallel with feed  112 . Antenna tuning may be provided by a tunable circuitry (e.g., a tunable impedance matching circuit or other circuit coupled to antenna  40  at feed terminals  98  and  100  in antenna feed  112 ) and/or by tunable components such as adjustable inductor  120 . Adjustable inductor  120  may span the dielectric gap formed by slot opening  114  and may be coupled between structures  16 B and ground extension  104 E in parallel with feed  112 . Adjustable inductor  120  may be adjusted to tune the frequency associated with the low communications band of antenna  40  or may be used to make other antenna tuning adjustments for antenna  40 . There may be capacitances associated with gaps  18 . If desired, fixed or tunable inductors may be coupled across gaps  18  to counteract the capacitance associated with gaps  18 . 
     As described in connection with resonating element arm  108  of inverted-F antenna resonating element  106  of  FIG. 4 , peripheral conductive housing structures  16 B may form an inverted-F antenna resonating element that covers one or more communications bands of interest. As an example, peripheral conductive housing structures  16 B may have a first portion such as portion LB of  FIG. 6  that supports a resonance at a low communications band (e.g., a band covering frequencies from 700 MHz to 960 MHz or other frequency range) and may have a second portion such as portion MB of  FIG. 6  that supports a resonance at a mid-frequency (“mid band”) communications band (e.g., a band covering frequencies from 1710 MHz to 2170 MHz or other frequency range). Slot  114  may serve as a slot resonating element that supports a resonance at a high communications band (e.g., a band covering frequencies from 2300 MHz to 2700 MHz or other frequency range). The low band, middle band, and high band may lie within a frequency range between 700 MHz and 2700 MHz or other suitable frequency range. If desired, other inverted-F slot hybrid antenna configurations may be used. The example of  FIG. 6  in which the inverted-F portion of the hybrid antenna supports low and mid band communications bands and in which the slot antenna resonating element supports communications in a high band is merely illustrative. 
     Transmission line  92  may have an impedance of 50 ohms or other suitable impedance. To help match the impedance of antenna  40  to the impedance of transmission line  92  and thereby enhance antenna performance, device  10  may be provided with an impedance matching circuit. For example, an impedance matching circuit such as matching circuitry  138  of  FIG. 7  may be coupled between positive antenna feed terminal  98  and ground antenna feed terminal  100 . Ground terminals  136  may be coupled to ground  104  (e.g., extension  104 E). Matching circuit  126  may include one or more components that form an impedance matching network such as inductors, capacitors, and resistors. Matching circuit  126  may be coupled between terminals  98  and  100 . Tunable inductor  120  ( FIG. 6 ), which may be coupled across slot  114  as shown in  FIG. 6 , may be implemented using switching circuitry  128  and inductors such as inductors  130 ,  132 , and  134 . Inductors  130 ,  132 , and  134  may have different values or two or more of these inductors may have the same value. Switching circuitry  128  may switch one or more of the inductors into use to adjust the overall inductance of adjustable inductor  120 . For example, control circuitry  28  can adjust switching circuitry  128  to adjust the inductance of inductor  120  so that antenna  40  can cover a desired communications band (e.g., inductor  120  may be adjusted to tune the low band). 
     Switching circuit (switch)  124  and inductor  122  may be connected in series and may be coupled to antenna  40  (e.g., at a feed terminal or other location). As an example, switch  124  and inductor  122  may be coupled across one of gaps  18  (or multiple such switchable inductors may be provided). Switch  124  may be controlled by control circuitry  28  and may be used to switch inductor  122  into use and out of use to compensate for potential antenna detuning in the presence of an external object in the vicinity of antenna  40  (e.g., in the vicinity of gap(s)  18 ). During operation in the absence of a hand or other external object adjacent to antenna  40 , switch  124  may be closed and inductor  122  may be switched into use. When a hand of a user or other external object is present in the vicinity of gap(s)  18  (i.e., adjacent to antenna  40 ), the capacitance of gap(s)  18  may rise. This rise in capacitance has the potential to detune antenna  40 . The presence of the user&#39;s hand may be detected using a proximity sensor (e.g., a capacitive proximity sensor, a light-based proximity sensor, etc.), using a temperature sensor, using a camera, using an impedance measuring circuit (e.g., feedback from directional coupler  95 ) to measure the impedance of antenna  40  or a portion of antenna  40  in real time, or using other detection techniques. 
     Due to the potential of a user&#39;s grip to detune antenna, switch  124  may be placed in an open condition whenever the presence of an external object in the vicinity of antenna  40  is detected. When switch  124  is opened in response to detection of the presence of the user&#39;s hand or other external object adjacent to antenna  40 , inductor  122  will be switched out of use and the frequency response (tuning) of antenna  40  will be maintained as desired. 
       FIG. 8  is a Smith chart illustrating the impact of using switching circuitry such as switch  124  to switch inductor  122  into and out of use. Transmission line  92  may have an impedance of 50 ohms (as an example), as illustrated by impedance  140 . When antenna  40  is operating normally (across a range of frequencies between 700 MHz and 2700 MHz or other frequency range), antenna  40  may exhibit an impedance such as illustrative impedance  142 . Impedance  142  may be associated with the use of inductor  122  of  FIG. 7  (i.e., antenna  40  will have impedance  142  when inductor  122  is switched into use by closing switch  124 ). 
     Impedance  142  is closely matched to transmission line impedance  140  as desired. Upon placing a user&#39;s hand or other external object in the presence of gap(s)  18  (i.e., adjacent to antenna  40 ), antenna impedance  142  may be detuned to impedance  146 , unless switch  124  is opened and inductor  122  is switched out of use. When switch  124  is opened and inductor  122  is switched out of use to adjust the operation of antenna  40  in response to detecting that the user&#39;s hand or other external object is present in the vicinity of gap(s)  18  (i.e., detecting that the user&#39;s hand is adjacent to antenna  40 ), antenna  40  will exhibit satisfactory impedance  144 . The use of switch  124  to switch inductor  122  in and out of use based on the absence or presence of the user&#39;s hand, respectively, may therefore ensure that antenna  40  is not detuned by an unacceptable amount. 
       FIG. 9  shows how an electronic component may be mounted in the vicinity of antenna  40  without disrupting the performance of antenna  40 . In the example of  FIG. 9 , button  24  has been provided with a fingerprint sensor such as fingerprint sensor  152 . Fingerprint sensor  152  may include a metal outer ring such as ring  150  or other electrode that supplies an alternating current signal. Ring  150  may surround central area  156 . Fingerprint sensor electrodes  154  may be formed in a one-dimensional or two-dimensional array in area  156 . When a user places a finger over region  156 , signals may be injected into the user&#39;s finger from ring  150  and picked up by the array of electrodes  154  in region  156 . This allows the fingerprint sensor  152  to measure fingerprint patterns for the user&#39;s finger. A captured fingerprint or other data from fingerprint sensor  152  may be conveyed to control circuitry  28  using metal signal traces on flexible printed circuit  158 . 
     Flexible printed circuit  158  may have an end portion such as portion  160  that overlaps extended portion  104 E of ground  104 . Because the metal traces on portion  160  and the metal structures of fingerprint sensor  152  overlap ground plane extension  104 E, antenna  40  operates properly without interference from the presence of fingerprint sensor  152 . In the example of  FIG. 9 , fingerprint sensor  152  overlaps extended portion  104 E and is mounted on a flexible printed circuit that extends between extended portion  104 E and ground  104  in the center of device  10 . This is merely illustrative. Fingerprint sensor  152  may be located in other portions of device  10  on ground plane extension  104 E or elsewhere overlapping ground  104 . 
       FIG. 10  shows how ground plane extension  104 E may be shorted to ground plane  104  through shorting structures  164 . Shorting structures  164  may include conductive structures  166  such as strips of metal foil, metal housing structures, metal traces on one or more flexible printed circuits, laser direct structuring metal traces on a plastic carrier, other metal on a dielectric carrier, metal clips, lengths of wire, or other conductive structures that electrically couple ground plane  104  to ground plane extension  104 E. Ground plane  104  and ground plane extension  104 E in this type of arrangement may be formed from machined metal parts (e.g., planar metal structures such as respective portions of a planar rear wall for housing  12 ). Conductive structures  166  may be coupled between ground plane  104  and ground plane extension  104 E using solder, welds, conductive adhesive, screws or other fasteners, or other conductive coupling structures. 
     Metal housing  12  may have gaps such as gaps  114  and  162  of  FIG. 10 . These gaps may be filled with plastic or other dielectric. Gap  114  may separate ground plane extension  104 E from peripheral metal housing structures  16 B. Gap  162  may separate the planar rear wall portion of metal housing  12  that forms structure  104 E from the planar rear wall portion of metal housing  12  that forms ground  104 . Gap  162  may be bridged using shorting structures  164 . The shorting structures electrically couple the portions of housing forming ground  104  and ground extension  104 E, so that ground extension  104 E serves as an extension of ground  104 . 
     Shorting structures  164  of  FIG. 10  may be formed on the interior of device  10 . When viewed from the exterior of device  10 , gap  114  and gap  162  may appear as shown in  FIG. 11 . As shown in  FIG. 11 , gaps  114  and  162  may be filled with a dielectric material such as plastic. The plastic may lie flush with the outer surface of housing  12 . The plastic in gap  162  may cover internal structures such as shorting structures  164  and may therefore hide these internal structures from view. 
       FIG. 12  is a cross-sectional side view of device  10  showing how fingerprint sensor  152  may be formed within button  24  in a portion of device  10  that overlaps ground extension  104 E. As shown in  FIG. 12 , display  14  may have a display cover layer such as display cover layer  178  and a display module such as display module  180 . Display cover layer  178  may be formed from a clear layer of glass, a transparent plastic layer, or other transparent material. Display module  180  may be a liquid crystal display module, may be an organic light-emitting diode display module, or may include display layers formed using other types of display technology. Display module  180  may be located in the center of device  10  overlapping the portion of housing  12  associated with ground plane  104 . Active area AA of  FIG. 1  may cover display module  180  of  FIG. 12 . 
     Ground plane  104  of  FIG. 12  may be formed from conductive structures such as housing  12 , display module  180 , a metal midplate (not shown in  FIG. 12 ), metal traces on printed circuit boards, etc. For example, ground plane  104  may be formed from a first planar portion of the rear wall of housing  12 . Display module  180  may overlap the central portion of antenna ground (i.e., the portion of ground  104  that is separated from extended ground portion  104 E by gap  162 ) without overlapping extended ground portion  104 E. Display cover layer  178  may overlap both the portion of ground  104  that is overlapped by display module  180  and extended ground portion  104 E. Extended ground portion  104 E may be formed from a second planar portion of the rear wall of housing  12 . 
     Plastic may be used to fill gap  162  between the portion of housing  12  forming ground plane  104  and the portion of housing  12  forming ground plane extension  104 E. Conductive structures  166  may electrically connect ground plane extension  104 E to housing  12  in ground plane  104 . Support structures such as structure  184  and receptacle  174  may form a female connector that receives male connector  182  (e.g., a connector coupled to the end of a cable or other accessory). Button  24  may overlap the connector that receives plug  182  (i.e., button  24  may overlap plug receptacle  174 ). Peripheral conductive structures  16 B may form a housing wall at the end of housing  12  (e.g., the lower end of housing  12 ). An opening may be formed in peripheral conductive structures  16 B to accommodate connector  182 . 
     Button  24  may be formed from a button member such as button member  170  surrounded by metal trim  150  (e.g., a metal ring). Button member  170  may be formed from a dielectric such as plastic or glass (as examples). Button  24  may include fingerprint sensor  152 . Fingerprint sensor  152  may be mounted under button member  170  (as an example). During operation, fingerprint sensor electrodes  154  in sensor  152  may be capacitively coupled to a user&#39;s finger through the dielectric of button member  170 . Metal ring  150  in button  24  may provide alternating current signals that are coupled to electrodes  154  through a user&#39;s finger during fingerprint capture operations. Sensor  152  may be coupled to metal traces on flexible printed circuit  158 . 
     Button  24  may have a switch such as switch  172 . Switch  172  may be mounted on the lower surface of fingerprint sensor  152 , so that button  24  and fingerprint sensor  152  in button  24  overlap switch  172  (as an example). When button  24  (i.e., button member  170 ) is pressed in a downwards direction (towards the interior of device  10 ), switch  172  will be compressed between button member  170  and underlying structures such as receptacle  174  or other support structures. When compressed, button  24  will change state (i.e., button  24  will transition from open to closed or vice versa due to actuation of switch  172 ). Switch  172  may be a dome switch or other suitable switch. Configurations for button  24  that use a capacitive touch sensor to implement button functionality (e.g., a switchless button) may be used, if desired. Because button  24  and fingerprint sensor  152  in button  24  overlap ground plane extension  104 E, the operation of antenna  40  will not be disrupted by the presence of button  24  and fingerprint sensor  152 . 
     The foregoing is merely illustrative and various modifications can be made by those skilled in the art without departing from the scope and spirit of the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20140819
Publication Date: 20170221
Grant Date: 20170221
Priority Date: 20140819
Inventors: PASCOLINI MATTIA
JIN NANBO
Assignee: APPLE INC
CPC Classifications: [{"code": "H04N23/54", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F21/32", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q13/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/0421", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F21/32", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/2258", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/0485", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/48", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q13/103", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04M1/026", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01Q3/247", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F21/32", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q13/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q13/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/38", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F21/32", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q13/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06K9/00006", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06V40/12", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06V40/12", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06V40/1306", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06V40/12", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F21/32", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q13/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 53938440