PATENT DOCUMENT

Publication Number: US-9633247-B2
Application Number: US-201213409615-A
Country: US
Kind Code: B2

Title: Electronic device with shared near field communications and sensor structures

Abstract:
An electronic device may have electrical components such as sensors. A sensor may have sensor circuitry that gathers sensor data using a conductive structure. The sensor may be a touch sensor that uses the conductive structure to form a capacitive touch sensor electrode or may be a fingerprint sensor that uses the conductive structure with a fingerprint electrode array to handle fingerprint sensor signals. Near field communications circuitry may be included in an electronic device. When operated in a sensor mode, the sensor circuitry may use the conductive structure to gather a fingerprint or other sensor data. When operated in near field communications mode, the near field communications circuitry can use the conductive structure to transmit and receive capacitively coupled or inductively coupled near field communications signals. A fingerprint sensor may have optical structures that communicate with external equipment.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 an array of conductive structures and an inductor that surrounds the array of conductive structures; 
 sensor circuitry that is coupled to the array of conductive structures and the inductor and that is configured to gather sensor data using the array of conductive structures and the inductor; and near field communications circuitry that is coupled to the inductor and that is configured to receive near field communications signals with the inductor, wherein signals are provided to an external object from the sensor circuitry through the inductor, wherein the signals are coupled from the external object to the array of conductive structures, wherein the array of conductive structures provides the signals to the sensor circuitry; and 
 near field communications circuitry that is coupled to the inductor and that is configured to receive near field communications signals with the inductor, wherein the near field communications circuitry comprises a near field communications transceiver that is coupled to the inductor and configured to transmit and receive rear field communications signals with the inductor. 
 
     
     
       2. The electronic device defined in  claim 1  wherein the electronic device is operable by a user having a finger, and wherein the external object comprises the finger. 
     
     
       3. The electronic device defined in  claim 2  wherein the inductor comprises a ring-shaped inductor. 
     
     
       4. The electronic device defined in  claim 3  further comprising a button, wherein the inductor is mounted to the button. 
     
     
       5. The electronic device defined in  claim 1  wherein the conductive structures comprise at least one sensor electrode. 
     
     
       6. The electronic device defined in  claim 5  wherein the near field communications signals are inductively coupled. 
     
     
       7. The electronic device defined in  claim 5 , further comprising:
 a plurality of additional inductors, wherein the near field communications circuitry comprises near field communications circuitry that is configured to transmit multiple streams of data in parallel through the plurality of inductors using inductively coupled near field communications signals. 
 
     
     
       8. The electronic device defined device in  claim 5  wherein the sensor electrode comprises at least one capacitor electrode. 
     
     
       9. The electronic device defined in  claim 8  wherein the sensor circuitry is configured to gather capacitively coupled sensor data using the capacitor electrode. 
     
     
       10. The electronic device defined in  claim 1  further comprising a button, wherein the conductive structures are mounted to the button. 
     
     
       11. The electronic device defined in  claim 10  wherein the conductive structures are configured to form at least one capacitor electrode on the button and wherein the sensor circuitry is coupled to the capacitor electrode and is configured to gather sensor data using the capacitor electrode. 
     
     
       12. The electronic device defined in  claim 10  wherein the inductor is formed on the button. 
     
     
       13. The electronic device defined in  claim 1  further comprising switching circuitry that is configured to selectively couple the sensor circuitry and the near field communications circuitry to the inductor. 
     
     
       14. The electronic device defined in  claim 1 , wherein the inductor comprises a single conductive structure that is used by both the sensor circuitry to gather the sensor data and by the near field communications circuitry to receive the near field communications signals. 
     
     
       15. An electronic device, comprising:
 sensor circuitry; 
 an array of conductive structures and at least one electrode, wherein the array of conductive structures and the electrode are coupled to the sensor circuitry, wherein the sensor circuitry is configured to gather sensor data using the electrode, wherein signals are provided to an external object from the sensor circuitry through the electrode, wherein the signals are coupled from the external object to the array of conductive structures, and wherein the array of conductive structures provides the signals to the sensor circuitry; and 
 near field communications transceiver circuitry that is coupled to the electrode and that is configured to transmit and receive near field communications signals with the electrode, wherein the electrode comprises a single conductor, wherein the sensor circuitry is configured to gather the sensor data and the near field communications transceiver circuitry is configured to transmit and receive the near field communications signals using the single conductor. 
 
     
     
       16. The electronic device defined in  claim 15  wherein the electrode is configured to form a capacitor structure and wherein the near field communications transceiver circuitry is configured to transmit and receive capacitively coupled near field communications signals using the capacitor structure. 
     
     
       17. The electronic device defined in  claim 16  further comprising a button, wherein the capacitor structure is mounted on the button. 
     
     
       18. The electronic device defined in  claim 16  further comprising a housing having a front face with a display, wherein the capacitor structure is mounted on the front face. 
     
     
       19. The electronic device defined in  claim 18  wherein the sensor circuitry comprises fingerprint sensor circuitry. 
     
     
       20. The electronic device defined in  claim 15 , wherein the single conductor is an inductor. 
     
     
       21. The electronic device defined in  claim 20 , wherein the near field communications transceiver circuitry is configured to transmit and receive inductively coupled near field communications signals using the inductor. 
     
     
       22. The electronic device defined in  claim 21 , wherein the sensor circuitry is configured to gather inductively coupled sensor data using the inductor. 
     
     
       23. The electronic device defined in  claim 15 , wherein the at least one electrode is one of a plurality of electrodes that are each coupled to the sensor circuitry and the near field communications circuitry, wherein the sensor circuitry is configured to gather the sensor data using each of the plurality of electrodes, and wherein the near field communications transceiver circuitry is configured to transmit and receive the near field communications signals using each of the plurality of electrodes. 
     
     
       24. The electronic device defined in  claim 15 ,
 wherein the single conductor surrounds the array of conductive structures, and wherein the sensor circuitry is configured to gather the sensor data using the array of conductive structures. 
 
     
     
       25. The electronic device defined in  claim 15 , further comprising switching circuitry that is configured to selectively couple the single conductor to the sensor circuitry and the near field communications transceiver circuitry. 
     
     
       26. The electronic device defined in  claim 15 , wherein the sensor circuitry and the near field communications circuitry simultaneously use the single conductor for gathering sensor data and for near field communications. 
     
     
       27. The electronic device defined in  claim 26 , further comprising coupler circuitry coupled to the sensor circuitry and the near field communications circuitry, wherein the coupler circuitry routes the sensor data and the near field communications signals between the single conductor and the sensor circuitry and between the single conductor and the near field communications circuitry. 
     
     
       28. An electronic device, comprising:
 an array of conductive structures and an inductor; 
 sensor circuitry coupled to the inductor and the array of conductive structures, wherein the sensor circuitry is configured to gather sensor data using the inductor, wherein signals are provided to an external object from the sensor circuitry through the inductor, wherein the signals are coupled from the external object to the array of conductive structures, and wherein the array of conductive structures provides the signals to the sensor circuitry; and 
 near field communications transceiver circuitry that is coupled to the inductor and that is configured to transmit and receive near field communications signals with the inductor. 
 
     
     
       29. The electronic device defined in  claim 28  wherein the near field communications transceiver circuitry is configured to transmit and receive inductively coupled near field communications signals using the inductor. 
     
     
       30. The electronic device defined in  claim 28 ,
 wherein the sensor circuitry is configured to gather the sensor data with both the inductor and the array of conductive structures.

Description:
BACKGROUND 
     This relates generally to electronic devices, and more particularly, to input-output circuitry such as sensor and communications circuitry for electronic devices. 
     Electronic devices such as portable computers and cellular telephones are often provided with input-output circuitry. The input-output circuitry may include electrical and optical circuits such as sensor circuits. Wireless communications circuitry may be provided for transmitting and receiving wireless signals. For example, electronic devices may include wireless communications circuitry such as cellular telephone circuitry, wireless local area network circuitry, and satellite navigation system circuitry. Some electronic devices use near field communications to wirelessly communicate with external equipment. 
     To satisfy consumer demand for small form factor devices, manufacturers are continually striving to implement input-output components such as sensors and wireless communications circuits using compact structures. Challenges can arise when incorporating input-output devices such as sensors and wireless circuits in an electronic device. For example, wireless component should generally not be blocked by conductive structures in a device, which can make it difficult to properly place a wireless component within an electronic device housing. If care is not taken, wireless devices and other input-output devices may consume more space within a device than is desired or may add undesired cost or complexity to a device. 
     It would therefore be desirable to be able to provide improved input-output circuitry such as improved wireless circuitry and sensor circuitry. 
     SUMMARY 
     An electronic device may have electrical components such as sensors. A sensor may have sensor circuitry that gathers sensor data. The sensor may be a touch sensor that uses a conductive structure to form a capacitive touch sensor electrode or may be a fingerprint sensor that uses a conductive structure associated with a fingerprint electrode array to handle fingerprint sensor signals. A touch sensor or fingerprint sensor may have an array of conductive electrodes for gathering sensor data from the front face of an electronic device, an edge of an electronic device, a button in an electronic device, or other portion of an electronic device. A fingerprint sensor or other sensor may also be formed using optical structures such as one or more light sources and receivers. 
     Near field communications circuitry may be included in the electronic device. Circuitry such as filter or switching circuitry may be used to couple both the near field communications circuitry and the sensor circuitry to a common conductive structure. This allows the conductive structure to be shared between sensor functions such as fingerprint or touch sensor functions and near field communications functions. 
     Control circuitry within the electronic device may operate the device in multiple modes. When operated in a sensor mode, the sensor circuitry may use the conductive structure to gather fingerprint data or other sensor data. When operated in near field communications mode, the near field communications circuitry can use the conductive structure to transmit and receive capacitively coupled or inductively coupled near field communications signals. 
     A fingerprint sensor formed using optical structures such as one or more optical transmitters and one or more receivers may gather fingerprint data optically. The control circuitry in the electronic device may use the optical structures of the fingerprint sensor in communicating with external equipment. 
     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 have a sensor or other component with structures that may be used in near field communications in accordance with an embodiment of the present invention. 
         FIG. 2  is a schematic diagram of a system including an illustrative electronic device having a sensor with structures that may be used in near field communications with external equipment and that may be used to sense a human body or other external object in accordance with an embodiment of the present invention. 
         FIG. 3  is a diagram of an illustrative sensor of the type that may be used in an electronic device of the type shown in  FIGS. 1 and 2  in accordance with an embodiment of the present invention. 
         FIG. 4  is diagram of a sensor with a circular ring-shaped electrode surrounding an array of electrodes in accordance with an embodiment of the present invention. 
         FIG. 5  is a cross-sectional side view of an illustrative sensor such as the sensor of  FIG. 4  mounted in a button in an electronic device in accordance with an embodiment of the present invention. 
         FIG. 6  is a diagram of an edge portion of an electronic device with an illustrative sensor having structures that may be used in near field communications in accordance with an embodiment of the present invention. 
         FIG. 7  is a diagram of an edge portion of an electronic device with another illustrative sensor having structures that may be used in near field communications in in accordance with an embodiment of the present invention. 
         FIG. 8  is a diagram showing how device structures may communicate with external equipment using capacitively coupled near field communications in accordance with an embodiment of the present invention. 
         FIG. 9  is a diagram of illustrative device circuitry and external equipment circuitry that may be used in inductively coupled near field communications in accordance with an embodiment of the present invention. 
         FIG. 10  is a diagram showing how device circuitry may be configured to sense an external object such as a portion of a human body and may be configured to wirelessly communicate with external equipment using near field communications in accordance with an embodiment of the present invention. 
         FIG. 11  is a diagram of illustrative circuitry that may be used in an electronic device to support use of conductive structures as part of a sensor and as part of a near field communications circuit in accordance with an embodiment of the present invention. 
         FIG. 12  is a perspective view of a portion of an electronic device having a sensor in a button that may be configured to take sensor readings and to perform near field communications operations in accordance with an embodiment of the present invention. 
         FIG. 13  is a perspective view of an illustrative electronic device being inserted into a mating cradle accessory in accordance with an embodiment of the present invention. 
         FIG. 14  is a perspective view of the electronic device of  FIG. 13  following insertion of the device into the cradle of  FIG. 13  in accordance with an embodiment of the present invention. 
         FIG. 15  is a cross-sectional side view of the electronic device of  FIGS. 13 and 14  following insertion of the device into the cradle of  FIGS. 13 and 14  in accordance with an embodiment of the present invention. 
         FIG. 16  is a side view of an illustrative electronic device and associated external equipment showing how the device may be oriented with respect to the external equipment during near field communications in accordance with an embodiment of the present invention. 
         FIG. 17  is a perspective view of sensor electrode structures and corresponding capacitively coupled structures in external equipment showing how the device and external equipment may use multiple pairs of structures in parallel to support capacitively coupled near field communications in accordance with an embodiment of the present invention. 
         FIG. 18  is a top view of overlapping conductive electrode structures on a device and external equipment that may be used in capacitively coupled near field communications in accordance with an embodiment of the present invention. 
         FIG. 19  is a top view of an illustrative sensor in an electronic device showing how sensor structures may be configured to form an inductor for performing inductively coupled near field communications with external equipment in accordance with an embodiment of the present invention. 
         FIG. 20  is a top view of an illustrative sensor structure that has been configured to form an inductor with an undulating perimeter that may be used in performing inductively coupled near field communications with external equipment in accordance with an embodiment of the present invention. 
         FIG. 21  is a top view of an illustrative sensor structure that has been configured to form an inductor with multiple loops that may be used in inductively coupled near field communications with external equipment in accordance with an embodiment of the present invention. 
         FIG. 22  is a cross-sectional side view of an illustrative optical sensor such as a fingerprint sensor being used to capture fingerprint data or otherwise sense an external object such as the finger or other body part of a user in accordance with an embodiment of the present invention. 
         FIG. 23  is a cross-sectional side view of an illustrative optical sensor of the type shown in  FIG. 22  being used to optically communicate with an external device in accordance with an embodiment of the present invention. 
         FIG. 24  is a cross-sectional side view of another illustrative optical sensor being used to capture fingerprint data or otherwise sense an external object such as the finger or other body part of a user in accordance with an embodiment of the present invention. 
         FIG. 25  is a cross-sectional side view of an illustrative optical sensor of the type shown in  FIG. 23  being used to optically communicate with an external device in accordance with an embodiment of the present invention. 
         FIG. 26  is a top view of device structures and overlapping external equipment structures configured to communicate using near field communications in accordance with an embodiment of the present invention. 
         FIG. 27  is a top view of a pair of device electrodes and a corresponding pair of oversized external equipment electrodes that may be used for capacitive coupled near field communications in accordance with an embodiment of the present invention. 
         FIG. 28  is a flow chart of illustrative steps involved in using a predetermined near field communications signal pattern on an array of electrodes to trigger actions in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices such as electronic device  10  of  FIG. 1  may be provided with sensors and other electronic components. Structures in these components may be configured to form capacitor structures, inductor structures, or other structures for supporting near field communications (NFC) in addition to sensor operations. If desired, optical structures may be used both in capturing fingerprint data or other sensor data and in performing optical communications with external equipment. 
     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 cellular telephone, or a media player. 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 . Display  14  may, for example, be a touch screen that incorporates capacitive touch electrodes. Display  14  may include image pixels formed form 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 cover layer such as a layer of clear glass or plastic may cover the surface of display  14 . Buttons such as button  19  may pass through openings in the display cover layer. The display cover layer may also have other openings such as an opening for speaker port  26 . 
     Display  14  may have an active region and an inactive region. For example, display  14  may have an active region such as central rectangular region  17 . Active region  17  may be bounded by rectangular periphery  13  and may be surrounded by an inactive region such as rectangular ring-shaped inactive region  15 . Active region  17  may contain active display pixels for displaying images for a user of device  10 . Inactive region  15  may be free of active image pixels. An opaque masking layer may be provided on the underside of the display cover layer for display  14  in region  15  to help hide internal components in device  10  from view by a user of device  10 . If desired, display  14  may be implemented using a borderless design and/or using display structures that cover some or all of the sidewalls and/or other surfaces of device  10 . The configuration of  FIG. 1  is merely illustrative. 
     Housing  12  may have openings such as openings  21 ,  23 , and  25 . Openings such as opening  23  may be used to form input-output ports (e.g., ports that receive analog and/or digital connectors such as Universal Serial Bus connectors, 30-pin data connectors, data connectors with 5-10 contacts, audio jack connectors, video connectors, or other connectors). Openings such as openings  21  and  25  may be used to accommodate electrical components such as audio components or other electrical devices. Opening  21  may, for example, form a microphone port and opening  25  may form a speaker port. Other portions of housing  12  such as other sidewall portions or other portions of the front or rear planar surface of device  10  may also be provided with structures to accommodate components. 
     Device  10  may have a front face (e.g., the front surface covered by display  14  in the example of  FIG. 1 ), an opposing rear face (e.g., a rear housing wall in housing  12 ), and sidewall structures such as sidewall structures  16  of housing  12  (as an example). Sensors for device  10  may be incorporated into components such as button  19 , may be formed on parts of the front face of device  10  such as region  27  in inactive area  15 , in part of active area  17 , on sidewall areas such as region  29 , on the rear of device  10 , or on other suitable portions of device  10 . 
     Sensors may, in general, be used for transmitting and or receiving signals. Examples of sensors include optical sensors (e.g., ambient light sensors, light-based proximity sensors, light-based fingerprint sensors, etc.), touch sensors (e.g., touch sensors based on capacitive electrodes, touch sensors based on acoustic signals, touch sensors based on force sensors, touch sensors based on light, etc.), heat sensors, and acoustic sensors. These sensors may have structures such as conductive structures that may be used in forming capacitor structures and/or inductor structures for supporting near field communications. These sensors may also include optical components that can be used both in performing sensing functions and in wirelessly communicating with external equipment. 
     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 wirelessly communicate with external equipment  130  (e.g., using near field communications and/or optical communications and/or other wireless communications arrangements). A user may use a finger or other human body part or external object (e.g., human body  138 ) to supply device  10  with user input. For example, a user&#39;s finger may be used to supply a touch command or fingerprint to device  10  to control the operation of device  10 . 
     As shown in  FIG. 2 , electronic device  10  may include 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 . The processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio codec chips, 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, near field communications protocols, etc. 
     Circuitry  28  may be configured to control the operation of sensors and to take suitable actions based on sensor data and other input. For example, circuitry  28  may gather input from a fingerprint sensor, a touch sensor, or other sensor components and may use this gathered input in controlling the operation of device  10 . 
     Input-output circuitry  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 input-output devices  32 . Input-output devices  32  may include touch screens, buttons, joysticks, click wheels, scrolling wheels, touch pads, key pads, keyboards, microphones, speakers, tone generators, vibrators, cameras, sensor circuitry  44  for fingerprint sensors, touch sensors (e.g., touch sensors in a touch screen or separate from a display), ambient light sensors, light-based proximity sensors, capacitive proximity sensors, heat sensors, accelerometers, and other sensors, light-emitting diodes and other status indicators, data ports, etc. A user can control the operation of device  10  by supplying commands through input-output devices  32  and may receive status information and other output from device  10  using the output resources of input-output devices  32 . 
     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, and other circuitry for handling wireless signals. Wireless signals can also be sent using light (e.g., using infrared communications). 
     Wireless communications circuitry  34  may include satellite navigation system receiver circuitry such as Global Positioning System (GPS) receiver circuitry  35  (e.g., for receiving satellite positioning signals at 1575 MHz) or satellite navigation system receiver circuitry associated with other satellite navigation systems. Transceiver circuitry  36  may handle 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communications, may handle the 2.4 GHz Bluetooth® communications band, and may handle other wireless local area network communications bands of interest (e.g., 60 GHz signals associated with IEEE 802.11ad communications). Circuitry  34  may use cellular telephone transceiver circuitry  38  for handling wireless communications in cellular telephone bands such as bands in frequency ranges of about 700 MHz to about 2700 MHz or bands at higher or lower frequencies. 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 wireless circuitry for receiving radio and television signals, paging circuits, etc. Transceiver circuitry  24  may be used in performing near field communications operations (e.g., using capacitively coupled or inductive near field communications structures). Transceiver circuitry such as transceiver circuitry  24  may also be used in transmitting and receiving optical signals (e.g., for establishing optical links with adjacent external equipment). 
     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. In near field communications schemes, wireless signals are typically conveyed over distances of 1 m or less, 100 cm or less, 10 cm or less, or 1 cm or less (as examples) and are not conveyed over larger distances. 
     Wireless communications circuitry  34  may include one or more 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 structure, patch antenna structures, inverted-F antenna structures, closed and open slot antenna structures, planar inverted-F antenna structures, helical antenna structures, strip antennas, monopoles, dipoles, 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. 
     To support near field communications using a capacitively coupled and/or inductively coupled near field communications structures, device  10  may include capacitor structures (e.g., capacitor electrodes), inductor structures (e.g., one or more looped conductors), and other conductive structures. If desired, some or all of these structures may be shared with sensor structures in sensor circuitry  44 . For example, some of the conductive structures in sensor circuitry  44  such as electrodes in a fingerprint sensor or touch sensor may be used in forming capacitor electrodes and/or inductors for near field communications using near field communications transceiver circuitry  24 . 
     As an example, conductive structures in a fingerprint sensor may be used in forming near field communications structures. An illustrative fingerprint sensor of the type that may have electrodes that serve as near field communications structures is shown in  FIG. 3 . As shown in  FIG. 3 , sensor circuitry  214  may include electrode structures  202 . Electrode structures  202  may include a ring-shaped electrode such as electrode  204  that surrounds an array (e.g., a one-dimensional array) of electrodes such as electrodes  206 . Electrodes  206  may be coupled to sensor circuitry  200  using respective signal lines  208 . 
     Sensor circuitry  200  may contain a signal source such as signal source  210 . During operation, a user may swipe a finger across electrode  204  and array  206 A of electrodes  206  (e.g., a user may move a fingertip downwards across electrodes  204  and  206 ). During finger swiping, signal source  210  may drive an alternating current signal (e.g., a signal from 1 to 5 MHz or other suitable frequency) into electrode  204 . This drive signal may be coupled into the user&#39;s finger from electrode  204  when the user&#39;s finger is placed over electrode  204  (i.e., due to the contact of the user&#39;s finger with at least some of electrode  204  or due to the close proximity of the finger to electrode  204  in scenarios in which electrode  204  and the user&#39;s finger are separated by an air gap or a layer of plastic, glass, or other dielectric). Each signal line  208  may be coupled between a respective electrode  206  and a corresponding sensor circuit in sensor circuitry  200 . The magnitude of the drive signal that is coupled to each of electrodes  206  from the user&#39;s finger may be measured by monitoring the signals on lines  208 . As fingerprint ridges pass over electrodes  206 , different amounts of signal are coupled into electrodes  206  from the finger. By providing a sufficiently dense array  206 A of electrodes  206  in sensor structures  202  (e.g., 1 or more per mm, 10 or more per mm, or 100 or more per mm), sensor circuitry  214  may be used to capture a digital representation of the user&#39;s fingerprint. 
     If desired, fingerprint sensors for device  10  may be formed using a two-dimensional array of electrodes. Consider, as an example, illustrative sensor circuitry  214  of  FIG. 4 . As shown in  FIG. 4 , sensor circuitry  214  may include electrode structures  202  such as outer ring electrode  204  and a two-dimensional array  206 A of electrodes  206 . Array  206 A may, as an example, include 90-100 rows and 90-100 columns of electrodes  206 . Other numbers of electrodes and other array shapes may be used in sensor circuitry  214  if desired. For example, array  206 A may include 100 or more electrodes  206 , 500 or more electrodes  206 , 1000 or more electrodes  206 , 5000 or more electrodes, or other suitable number of electrodes. Outer electrode  204  may have a circular shape, an oval shape, a rectangular ring shape, or other suitable shape (e.g., other ring shapes or non-ring shapes). 
     Sensors such as the sensors of  FIGS. 3 and 4  may, if desired, be incorporated into parts of device  10  such as button  19 , portions of display  14  such as region  27  or part of active region  17 , edge portions of device  10  such as region  29 , etc. In the example of  FIG. 4 , a fingerprint sensor has been formed as part of button  19 . 
       FIG. 5  is a cross-sectional side view of a button such as button  19  of  FIG. 4  in which fingerprint sensor circuitry  214  has been formed. As shown in  FIG. 5 , button  19  may be formed from a button member such as button member  218 . Button member  218  may be received within an opening in display cover layer  216  in display  14  and may move up and down in vertical dimension  230 . When pressed downwards, button member  218  may compress dome switch  228  on support structure  226 , thereby closing switch  228 . When released, dome switch  228  or other biasing structures may force button member  218  to move upwardly towards its original position. Control circuitry  28  ( FIG. 2 ) may sense when switch  228  is closed and when switch  228  is open and can take suitable action. 
     Fingerprint sensor  214  may include an array of sensor electrodes such as array  206 A of electrodes  206 . Array  206 A may be, for example, a rectangular array such as array  206 A of  FIG. 4 . Ring-shaped electrode  204  may be a circular ring or a ring of other suitable shape that surrounds electrode array  206 A. 
     Electrodes  204  and  206  may be formed on a substrate such as substrate  220  (e.g., a plastic substrate, a printed circuit such as a flexible printed circuit formed from a sheet of polyimide or other polymer layer or a rigid printed circuit board, or other dielectric such as glass or ceramic). Member  218  may be formed from glass, plastic, ceramic, or other suitable dielectric materials. Substrate  220  may be attached to the underside of member  218 , may be embedded within member  218  (e.g., by laminating substrate  220  between other layers, using insert molding, or using other suitable fabrication techniques). Conductive traces  208  may be used to route signals from the electrodes to associated sensor circuitry such as sensor circuitry  200  (e.g., via a cable with wires, using a flexible printed circuit cable such as cable  224 , etc.). 
     If desired, an array of sensor electrodes for a fingerprint sensor or a capacitive touch sensor may be formed on an edge portion of device  10  such as edge portion  29  ( FIG. 1 ).  FIG. 6  is a perspective view of an edge portion of housing  12  of device  10  showing how electrodes  206 ′ may be formed in two or more rows and two or more columns along the edge of device  10  such as edge portion  29 . A sensor formed using electrodes  206 ′ of  FIG. 6  may be used for capturing a user&#39;s fingerprint and/or for serving as a touch sensor that receives user input to control the operation of device  10  (e.g., a touch sensor that receives commands that direct device  10  to scroll through content on display  14 , a touch sensor that receives gesture input, or other suitable touch sensor). 
     In the illustrative configuration of  FIG. 7 , electrodes  206 ′ have been configured to form a one-dimensional array that runs parallel to the edge of device  10 . As with electrode structures  202  of  FIGS. 3 and 4 , electrodes  206 ′ of  FIGS. 6 and 7  may, if desired, be configured to form a sensor such as a fingerprint sensor. Electrodes such as electrodes  206 ′,  206 , and  204  may also be configured to form capacitive touch sensor electrodes. Electrodes in regions of device  10  such as button  19 , region  27  of inactive display area  15 , active region  17 , edge region  29 , or other regions of device  10  may, for example, form touch sensors for detecting user gestures and other touch commands. Electrodes (for touch sensors and/or fingerprint sensors) may be formed from conductive materials such as metal, indium tin oxide or other transparent conductive materials, or other suitable materials. 
     Near field communications for device  10  may be supported using capacitive coupling near field communications structures and/or inductive coupling near field communications structures. 
     An illustrative capacitive coupling near field communications arrangement that may be used by device  10  to communicate with external equipment  130  is shown in  FIG. 8 . As shown in  FIG. 8 , device  10  may have capacitor electrodes such as electrodes  230  and  232 . Mediator  242  may be a human body or part of a human body, air or other dielectrics, conductive materials, or other interposed material between device  10  and external equipment  130 . External equipment may have capacitor electrodes such as electrodes  244  and  246 . Electrodes such as electrodes  230  and  246  may be coupled via an imaginary short. During transmission from device  10  to equipment  130 , electrode  232  may induce changes in charge on the adjacent portion of mediator  242 , which results in corresponding induced charge changes on the far side of mediator  242  and electrode  244 . During transmission from equipment  130  to device  10 , electrode  244  may induce changes in the charge on the portion of mediator  242  that is adjacent to electrode  244  that likewise result in changes in the signal on electrode  232 . 
     Near field transceiver circuitry (e.g., transceiver circuitry  24  of  FIG. 2 ) may include a near field transmitter such as transmitter  234  and a near field receiver such as near field receiver  236 . Transmitter  234  may supply differential output signals on output paths  238  and  240 , respectively. These output signals may be supplied to capacitor electrodes  230  and  232 . During signal reception operations, signals from capacitor electrodes  230  and  232  may be received on paths  238  and  240  by differential receiver  236 . 
     External equipment  130  may have near field transceiver circuitry  134  including a transmitter such as transmitter  248  for driving output signals onto electrodes  244  and  246  via paths  252  and  254 , respectively and including a receiver such as receiver  250  for receiving signals from electrodes  244  and  246  via paths  252  and  254 , respectively. 
     During operation, capacitively coupled signals from the near field transmitter in device  10  may pass through mediator  242  to reach the near field receiver in external equipment  130 . When it is desired to convey signals from external equipment  130  to device  10 , the near field transmitter in external equipment  130  may transmit signals that pass through mediator  242  to the near field receiver in device  10 . In free space near field coupling scenarios, mediator  242  may be primarily made up of air. In body coupled communications scenarios, mediator  242  may be all or part of the user&#39;s body. 
     Electrodes in device  10  such as electrodes  232  and  230  may be formed from conductive structures in device components. For example, one or more capacitor electrodes in device  10  may be made up of electrodes in a touch sensor, fingerprint sensor, or other sensor circuitry. The touch sensor electrodes that are used as near field communications capacitive coupling structures in an arrangement of the type shown in  FIG. 8  may be, for example, one or more capacitive touch sensor electrodes in a touch sensor (see, e.g., electrodes  206 ′ in a touch sensor on the edge of device  10 , touch sensor electrodes in display  14 , touch sensor electrodes on a track pad or other touch sensitive device, etc.), one or more sensor electrodes in a fingerprint sensor (e.g., one or more electrodes such as electrodes  206  and  204 ), or other electrode structures. External equipment  130  may be an electronic accessory, a point of sale terminal, a computer, or other external equipment. Capacitor electrodes  244  and  246  may be formed from metal plates or other suitable conductive structures. If desired, the shapes of electrodes  230 ,  232 ,  244 , and  246  may be configured to enhance capacitive coupling. For example, electrode  244  may be configured to have a ring shape that matches a ring shape used for electrode  232 . 
     An illustrative inductive coupling near field communications arrangement that may be used by device  10  to communicate with external equipment  130  is shown in  FIG. 9 . As shown in  FIG. 9 , device  10  may have inductive structures such as inductor  260 . Inductor  260  may have a pair of terminals coupled to paths  238  and  240 , respectively. Inductor  260  may be used to convey wireless signals through the air (or other medium). When transmitting, signals from inductor  260  may be received by inductor  262  in external equipment  130 . When external equipment  130  is transmitting wireless signals with inductor  262 , inductor  260  in device  10  may be used in receiving the transmitted signals. 
     Near field transceiver circuitry  24  in device  10  may include a near field transmitter such as transmitter  234  and a near field receiver such as near field receiver  236 . Transmitter  234  may supply differential output signals on output paths  238  and  240 , respectively. These output signals may be supplied to the terminals of inductor  260 . During signal reception operations, signals from inductor  260  may be received on paths  238  and  240  by differential receiver  236 . 
     External equipment  130  may have near field transceiver circuitry that includes a transmitter such as transmitter  248  for driving output signals through inductor  262  via paths  252  and  254 , respectively and that includes a receiver such as receiver  250  for receiving signals from inductor  262  via paths  252  and  254 , respectively. 
     During operation, inductively coupled signals from the near field transmitter in device  10  may be wirelessly conveyed to the near field receiver in external equipment  130 . When it is desired to convey signals from external equipment  130  to device  10 , the near field transmitter in external equipment  130  may transmit signals using inductor  262  that are received by inductor  260  in device  10 . 
     Inductive structures such as inductor  260  in device  10  may be formed from conductive structures in device components. For example, one or more inductive structures in device  10  (e.g., inductor  260 ) may be made up of conductive structures in a touch sensor, fingerprint sensor, or other sensor circuitry. The touch sensor electrodes that are used as near field communications inductive coupling structures in an arrangement of the type shown in  FIG. 9  may be, for example, one or more touch sensor electrodes in a touch sensor, one or more sensor electrodes in a fingerprint sensor, or other electrode structures. To ensure that the conductive structures exhibit sufficient inductance, the conductive structures can be configured to form conductive loops (e.g., loops with one or more turns of conductive lines). External equipment  130  of  FIG. 9  may be an electronic accessory, a point of sale terminal, a computer, or other external equipment. 
       FIG. 10  is a diagram showing how device  10  may have structures such as sensor/NFC structures  22  that are used both as near field communications elements (e.g., capacitor plates such as electrode  230  and/or electrode  232  or parts of such conductive capacitor structures) and inductive elements (e.g., inductor  260  or part of inductor  260 ) and as elements of an electronic component such as a sensor component (e.g., as an electrode in a fingerprint sensor, an electrode in a touch sensor, etc.). As shown in  FIG. 10 , device  10  may use sensor/NFC structures  22  to receive input from an external object such as a user&#39;s finger (finger  138  of  FIG. 10 ) and may communicate wirelessly (see, e.g., wireless signal  128 ) with external equipment using near field communications. With this type of arrangement, sensor circuitry  44  and near field transceiver  24  may share structures  22  in device  10 , reducing component count and helping to ensure that near field communications structures  22  are well placed on device  10  (i.e., so that near field communications structures are not blocked by portions of a conductive housing or conductive device structures). 
     Device  10  may be a cellular telephone, a tablet computer, a laptop computer, a desktop computer, a wristwatch device or other miniature or wearable device, a handheld device or other portable device, or other suitable electronic equipment. External equipment  130  may be a peer device (e.g., a device such as device  10  that is operated by another user), a device accessory (e.g., a cradle that can receive device  10 , headphones or other audio accessories, etc.), a near field communications point of sale terminal for handling wireless payments and other wireless transactions, a near field communications reader associated with security equipment (e.g., a door opener, a badge reader, etc.), a computer with near field communications capabilities (e.g., for security), a kiosk, embedded equipment in automated product or service dispensing equipment, equipment in an automobile, or other external equipment. 
     In a typical system environment, device  10  may sometimes communicate with one type of near field communications equipment and may, at other times, communicate with one or more other types of near field communications equipment. For example, a user of device  10  may place device  10  near to a point of sale terminal when it is desired to make a wireless payment, may place device  10  near a door lock when it is desired to obtain access to a building, may place device  10  near a security card reader when it is desired to authenticate to a computer system, and may place device  10  near to an audio device when it is desired to communicate with the audio device using near field communications. 
     As shown in  FIG. 10 , electronic device  10  and external equipment  130  may include control circuitry  28  and  136 , respectively. Control circuitry  28  and  136  may include microprocessors, microcontrollers, digital signal processors, application-specific integrated circuits, storage such as volatile and non-volatile memory (e.g., hard drives, solid state drives, random-access memory, etc.), and other storage and processing circuitry. 
     Device  10  and external equipment  130  may also include transceiver circuitry such as transceiver circuitry  24  and  134 , respectively. Transceiver circuitry  24  and  134  may include one or more radio-frequency transmitters, one or more radio-frequency receivers, both transmitters and receivers, or other suitable communications circuitry for generating radio-frequency signals for near field communications (e.g., transceiver circuitry operable at an NFC communications band at 13.56 MHz or other suitable frequency). 
     With one illustrative arrangement, device  10  includes a transmitter (i.e., transceiver  24  may be a transmitter) and equipment  130  includes a corresponding receiver (i.e., transceiver  134  may be a receiver). This type of arrangement may be used to support unidirectional near field communications between device  10  an external equipment  130 . If desired, bidirectional near field communications may be supported. For example, transceiver  24  may include a transmitter and a receiver and transceiver circuitry  134  may include a transmitter and a receiver. Wireless near field communications signals  128  may, in general, be communicated from device  10  to equipment  130 , from equipment  130  to device  10 , or both from device  10  to equipment  130  and from equipment  130  to device  10 . 
     Device  10  may include structures  22 . Structures  22  may include structures that are configured both as near field communications elements (e.g., capacitors and/or inductors) and as electrodes in a fingerprint sensor, touch sensor, or other electrical component. Structures  132  may include near field communications structures such as capacitors or inductors that are configured to communicate with structures  22  using near field communications. 
     The structures of elements  22  and  132  are capable of transmitting and/or receiving near-field-coupled radio-frequency electromagnetic fields. When used as a sensor, structures  22  and sensor circuitry  44  may be used to capture a fingerprint from finger  138  or to gather touch input from finger  138  or other external object. 
     An illustrative configuration that may be used for sharing sensor/NFC conductive structures  22  between near field communications circuitry such as near field communications transceiver  24  and the circuitry associated with additional components such as sensor circuitry  44  is shown in  FIG. 11 . As shown in  FIG. 11 , device  10  may include structures  22  for use in near field communications (e.g., to serve as an inductive near field communications element or capacitive near field communications element) and for use as part of an electronic component such as a sensor. Structures  22  may be based on inductive structures (e.g., electrodes patterned as looped conductors that form one or more inductors), capacitor structures (e.g., one or more capacitor electrodes), or other near field communications structures (e.g., near field communications antenna structures). Terminal  46  may form a first terminal for structures  22  and terminal  48  may form a second terminal for structures  22 . 
     Circuitry  124  may include transceiver circuits such as near field communications transceiver circuitry  24 . Transceiver circuitry  24  may be used to transmit wireless payment information, media data, streaming data (e.g., when device  10  has been paired with an audio or video accessory), voice and data associated with a telephone call (e.g., when device  10  has been paired with audio equipment in an automobile), security card information, wireless lock information, or other information. Circuitry  124  may also include other circuitry (i.e., non-NFC circuitry) such as sensor circuitry  44 . Sensor circuitry  44  may be associated with a fingerprint sensor, a touch sensor array for gathering other user touch input, a capacitance-based button, or other capacitive sensor. 
     Circuits  24  and  44  may be implemented using one or more integrated circuits. For example, circuit  24 , circuit  44 , and one or more integrated circuits in control circuitry  28  may be implemented using separate integrated circuits. If desired, circuit  24  and circuit  44  (and, optionally one or more control circuits within control circuitry  28 ) may be implemented using a common integrated circuit. 
     Circuit  42  may be used to couple multiple circuits such as near field communications transceiver  24  and sensor circuitry  44  to shared structures  22 . Circuit  42  may, for example, be a passive coupler that allows circuits  24  and  44  to operate simultaneously. With this type of arrangement, frequency-based multiplexing may be used to accommodate sharing of structures  22 . As an example, near field communications transceiver  24  may be configured to operate at a first radio frequency such as 13.56 MHz and sensor circuitry  44  may be configured to operate at a second radio frequency such as a frequency in the range of about 1-3 MHz, 1-10 MHz, less than 10 MHz, or other suitable frequency (as examples). In this type of arrangement, circuitry  42  can be configured to form a frequency-based multiplexing filter that routes signals to and from structures  22 ,  24 , and  44  based on their frequency. 
     If desired, circuitry  42  may be implemented using switching circuitry that selectively couples either circuit  24  or circuit  44  to terminals  46  and  48  in response to control signals received from control circuitry  28 . This type of arrangement allows control circuitry  28  to configure circuitry  42  so that near field communications transceiver  24  can transmit and/or receive near field communications signals using structures  22  or to configure circuitry  42  so that sensor circuitry  44  can use structures  22  to gather capacitive sensor signals (e.g., from a fingerprint sensor, a touch-based button, a touch sensor array for a track pad or touch screen, or other touch sensor). 
     If desired, switching circuitry configurations of this type may be used to selectively couple three or more transmitters to a near field communications element. 
     Path  50  may be used to convey one or more control signals between control circuitry  28  and switching circuitry  42 . When it is desired to transmit and/or receive NFC signals with NFC transceiver  24 , control circuitry  28  may provide control signals to switching circuitry  42  via control path  50  that direct switching circuitry  42  to operate in a near field communications (NFC) mode. In the NFC mode, NFC transceiver  24  may be coupled to structures  22  and may be used in conveying NFC signals (e.g., wireless NFC data for a wireless payment, for wireless data synching, for security applications, for wireless lock functions, etc.) to external equipment (e.g., a wireless point of sale terminal, etc.). When it is desired to convey capacitive sensor signals between structures  22  and sensor circuitry  44 , control circuitry  28  may provide control signals to switching circuitry  42  over path  50  that direct switching circuitry  42  to operate in a sensor mode (e.g., a fingerprint sensor mode, touch sensor mode, etc.). After placing switching circuitry  42  in the sensor configuration, sensor circuitry  44  may be used to process sensor signals from structures  22  (e.g., to capture a fingerprint, to gather touch commands, etc.). Because structures  22  can be used for both near field communications and sensor functions, the hardware resources associated with supporting these operations in device  10  may be minimized. The sharing of structures  22  between near field communications and sensor functions may also make it easier to mount conductive structures  22  at an appropriate location within the potentially compact volume available within device  10 . 
     If desired, structures  22  may be integrated into a button such as button  19  of device  10 . This type of configuration is shown in  FIG. 12 . As shown in  FIG. 12 , a user may place a finger such as finger  138  over button  19  during use of device  10 . Device  10  may use a switch under button  19  to detect button presses. Device  10  may use sensor circuitry  44  and structures  22  in button  19  to capture fingerprints (or other capacitive sensor data). When it is desired to use transceiver circuitry  24  for near field communications, structures  22  in button  19  may be used in transmitting and/or receiving near field communications. 
     Using structures  22  that have been incorporated into region  27 , into region  29 , into button  19 , or other portions in device  10 , device  10  may communicate with mating near field communications structures (e.g., structures  132  and circuitry  134  of  FIG. 10 ) when mated with external equipment such as illustrative accessory  130  of  FIG. 13 . Accessory  130  may be, for example, external equipment such as a cradle having an opening such as opening  300 . Cradle  130  may be implemented using a stand-alone housing or may be incorporated into an automobile system, stereo system, television, or other equipment. 
     In the configuration shown in  FIG. 13 , device  10  has not yet been inserted into opening  300 . In the configuration shown in  FIG. 14 , device  10  has been mated with accessory  130 . In particular, device  10  has been inserted into opening  300 , so that the lower end of device housing  12  is surrounded by the sidewalls of opening  300 , holding device  10  in place on accessory  130 . As shown in the cross-sectional side view of  FIG. 15 , this allows wireless near field communications signals to be conveyed between structures  22  in device  10  (e.g., structures  22  in button  19  and/or a region such as region  27  on a touch screen or inactive portion of a display) and near field communications structures  132  in equipment  130 . 
       FIG. 16  shows how device  10  may be held in place (e.g., manually by a user or using support structures) so that structures  22  face structures  132  in external equipment  130 . With a configuration of the type shown in  FIG. 16 , external equipment  130  may be a peer device (e.g., another device such as device  10 ), may be external equipment such as a point of sale terminal, may be part of a computer, may part of an embedded system in an automobile, may be audio or video equipment, or may be any other suitable external device. 
     Structures  22  may include patterned conductive structures. For example, structures  22  may have an array of rows and columns of electrodes. There may be tens or hundreds of individual electrodes (e.g., in a fingerprint sensor) or there may be fewer electrodes (e.g., in a touch-based button or touch sensor). In configurations with numerous individual electrodes, clusters of electrodes (e.g., sub-arrays including multiple rows and multiple columns of electrodes) may be electrically coupled together during near field communications operations (e.g., to form one or more larger electrodes each of which is made up of a number of smaller electrodes that have been shorted together). 
     When multiple electrodes are available in structures  22  (e.g., when multiple clusters of smaller electrodes and/or multiple individual electrodes are available), electrodes may be used in parallel to support capacitively coupled near field communications (e.g., to enhance throughput and/or reliability). This type of scheme is illustrated in  FIG. 17 . As shown in  FIG. 17 , structures  22  may include multiple electrodes such as electrodes  22 - 1  and  22 - 2 . When aligned with corresponding capacitor electrodes in near field communications structures  132  such as electrodes  132 - 1  and  132 - 2 , structures  22  and  132  may be used to support parallel near field communications (e.g., with one data stream being conveyed between electrodes  22 - 1  and  132 - 1 , with one data stream being conveyed between electrodes  22 - 2  and  132 - 2 , etc.). Any suitable number of electrodes in structures  22  may be used in performing parallel near field communications in this way (e.g., two or more, three or more, four or more, five or more, ten or more, etc.). Switching circuitry  42  ( FIG. 11 ) may be used in selecting which electrodes in structures  22  should be used in real time (e.g., based on signal strength measurements or other suitable control schemes). 
     In some scenarios, a user may not align structure  22  sufficiently with structures  132  to support parallel communications using all available electrodes. In this type of situation, device  10  can automatically select a subset of electrodes for use in performing near field communications.  FIG. 18  is a top view of structures  22  and structures  132  in a configuration in which only a subset of the available electrodes in structures  22  and  132  overlap (i.e., only electrodes  22 - 1  and  132 - 1 ). In this illustrative arrangement, only electrodes  22 - 1  and  132 - 1  participate in supporting near field communications. When more overlapping electrodes become available, switching circuitry  42  may be used to automatically switch additional electrodes into use. 
     As shown in  FIG. 19 , structures  22  may be configured to form inductive structures for use in inductively coupled near field communications. In the illustrative configuration of  FIG. 19 , structures  22  include an array of electrodes such as electrode array  206  (e.g., for a fingerprint sensor) and include a surrounding ring of conductive material such as ring  204  (e.g., a conductive ring such as metal ring  204  of  FIG. 4 ). Ring  204  may be provided with a gap such as gap  302 . Terminals such as terminals  46  and  48  may be formed on opposing sides of gap  302 . With this type of configuration, electrode  204  may form an electrode in a fingerprint sensor and may also form a one-loop inductor for use in inductively coupled near field communications. 
       FIG. 20  shows how loop-shaped electrode  204  may be provided with an undulating shape. The undulating shape of  FIG. 20  may help enhance near field coupling performance. 
     In the illustrative configuration of  FIG. 21 , electrode  204  has been provided with multiple turns, thereby increasing the inductance of structures  22  (i.e., inductor  204 ) for use in inductively coupled near field communications. In the examples of  FIGS. 19, 20, and 21 , structures  22  include an array of electrodes  206 A (e.g., for a fingerprint sensor). 
     In general, any suitable conductive structures  22  (e.g., capacitive electrodes in a touch sensor, conductive structures associated with other electrical components, etc.) may be used in forming near field communications structures. The configurations of  FIGS. 19, 20, and 21  are merely illustrative. 
     If desired, structures  22  may be used to form part of short range optical communications circuitry and optical components such as optical sensors. As an example, the optical transmitter and receiver structures that are used in an optical fingerprint sensor or other optical component may be used in forming optical transmitters and/or receivers that allow device  10  to wirelessly communicate with external equipment  130 . 
       FIGS. 22 and 23  are cross-sectional side views of optical structures  304  of the type that may be used in both short-range optical communications and in sensing operations for device  10 . 
     In the arrangement shown in  FIG. 22 , a user has placed an external object such as finger  138  in the vicinity of optical structures  306 . Optical structures  306  may include optical transmitters such as transmitters  306 T and optical receivers such as receivers  306 R. Transmitters  306 T may be, for example, infrared or visible light sources such as light-emitting diodes or lasers. Receivers  306 R may be, for example, infrared or visible light receivers such as photodiodes or phototransistors. In the configuration of  FIG. 22 , structures  306  are being used as a fingerprint sensor. There may be, for example, an array having numerous rows and columns of transmitters and receivers. Each transmitter  306 T may transmit light and each receiver  306 R may measure that amount of transmitted light that is reflected from the surface of finger  138 . Reflected light intensity is influenced by the pattern of surface features on finger  138 , so the configuration of  FIG. 22  may be used as an optical fingerprint sensor that captures a digital fingerprint from finger  138 . 
     When it is desired to use structures  306  to support optical communications with external equipment  130 , device  10  may be aligned with external equipment  130 , as shown in  FIG. 23 . Device  10  may, as an example, be held in place by a user so that optical structures  306  align with corresponding optical structures  308  in external equipment  130 . As shown in  FIG. 23 , optical structures  308  may include one or more optical transmitters  308 T and one or more optical receivers  308 R. When aligned as shown in  FIG. 23 , transmitters  306 T can transmit light  310  that is received by receivers  308 R and transmitters  308 T may transmit light  312  that is received by receivers  306 R. In configurations with only a single receiver/transmitter pair, structures  306  and  308  may support unidirectional communications. In configurations with multiple transmitters and receivers, structures  306  and  308  may support bidirectional communications. When structures  306  and  308  each contain multiple transmitters and receivers, multiple parallel data streams may be conveyed in parallel between device  10  and external equipment  130 , thereby enhancing throughput and/or reliability. 
     If desired, an optical sensor such as an optical fingerprint reader or touch sensor may have a configuration of the type shown in  FIGS. 24 and 25 . As shown in  FIG. 24 , optical structures  306  may include an optical source such as source  306 T and an array of receivers  306 R (e.g., a one-dimensional or two-dimensional array having tens, hundreds, or thousands of receivers  306 R). Optical source  306 T may be, for example, a light-emitting diode, a light-emitting diode array, one or more laser diodes, or other light source. Light source  306 T may launch light  321  into edge  328  of light guide structure  332 . Light  321  may be guided within light guide structure  332  by total internal reflection from upper surface  320  and lower surface  322 , as illustrated by reflected light  326 . Some of light  326  may escape vertically upwards to illuminate finger  138 . Light detectors  306 R may then measure the intensity of reflected light from finger  138  (e.g., to capture an optical fingerprint image). 
     Light guide structures  332  may be formed from a planar optically transparent member such as a sheet of plastic or glass or a transparent coating on a substrate. Structures  332  may have a portion such as portion  330  that helps direct light  326  upwards in a localized area. 
     As shown in  FIG. 25 , when it is desired to communicate optically between device  10  and external equipment  130 , device  10  and external equipment may be placed sufficiently close to each other to align optical structures  308  in external equipment  130  and optical structures  306  in device  10 . For example, portion  330  of light guide plate  332  may be aligned with receiver  308 R of optical structures  308 , so that portion  326 ′ of light  326  from light source  306 T can be detected by light receiver  308 R. Optical structures  308  may include a light source such as light transmitter  308 T for transmitting light  340  to one or more of receivers  306 R such as receiver  306 R′ in optical structures  306  of device  10 . When device  10  desires to optically transmit information to external equipment  130 , control circuitry  28  can use transceiver circuitry (e.g., transceiver circuitry  24  of  FIG. 2 ) to modulate the output of light source  306 T, thereby transmitting data via light  326 ′ to receiver  308 R in external equipment  130 . External equipment  130  may optically transmit information to device  10  by modulating the output of light source  308 T, thereby transmitting data via light  340  that can be detected by receiver  306 R′. 
     Optical structures such as structures  306  in device  10  may be formed as part of a button such as button  19 , may be formed in regions such as regions  27  and  29  of  FIG. 1 , or may be formed elsewhere on housing  12 . Optical structures such as structures  308  may be formed in an opening such as opening  300  of a cradle such as cradle  130  of  FIGS. 13, 14, and 15 , or may be formed elsewhere in external equipment  130 . Optical structures  306  may include an array of receivers such as receivers  306 R for capturing digital fingerprints or may include optical transmitter and receiver circuitry for performing other sensor functions (e.g., proximity sensing, ambient light sensing, etc.). The use of optical structures  306  to form an optical fingerprint sensor (in fingerprint sensor mode) and to form structures for supporting optical communications with nearby external equipment  130  (e.g., a cradle or other accessory, a peer device such as device  10 , or other external equipment) is merely illustrative. 
     In configurations for device  10  in which sensor/NFC structures  22  are being used to support capacitive near field communications with external equipment  130 , it may be challenging to properly align one or more of the electrodes in structures  22  with corresponding electrode structures in near field communications structures  132  of external equipment  130 . For example, a user may find it difficult to hold button  19  and structures  22  on button  19  in precise alignment with corresponding structures  132  on equipment  130  (e.g., due to hand movement, etc.). There may also be an air gap between structures  22  and  132  that can cause electromagnetic fields to spread and weaken, potentially disrupting effective near field communications. 
     To ensure satisfactory performance under conditions such as these, structures  132  may be provided with enlarged dimensions relative to structures  22 . If, as an example, there is one electrode in structures  22  such as ring-shaped electrode  204  of  FIG. 26 , structures  132  may be provided with a mating electrode such as electrode  132 ′ that has larger lateral (X and Y) dimensions than the dimensions of electrode  204 . 
     In the  FIG. 26  example, electrode  204  of structures  22  has a ring shape and corresponding electrode  132 ′ of structures  132  has a larger (wider) ring shape. In structures  22  with one or more electrodes with different shapes, structures  132  may be provided with one or more correspondingly enlarged electrodes with different shapes. If, for example, structures  22  include two rectangular electrodes that are used to support capacitively coupled near field communications such as electrodes  22 A and  22 B of  FIG. 27 , structures  132  may be provided with two corresponding rectangular electrodes such as electrodes  132 - 1  and  132 - 2 . Electrodes  132 - 1  and  132 - 2  may be larger in area than electrodes  22 A and  22 B to enhance capacitive coupling. 
     The larger areas of the electrode(s) in structures  132  relative to the electrode(s) in structures  22  may therefore help ensure satisfactory near field communications performance, even when structures  22  and  132  are somewhat misaligned. The larger size of the enlarged electrodes (e.g., the receiving electrodes) relative to the other electrodes (e.g., the transmitting electrodes) may help account for a wider and weaker electromagnetic field distribution from the transmit electrode while maintaining separation between parallel channels in scenarios in which multiple data streams are being transmitted in parallel using multiple pairs of mating transmitting and receiving electrodes. 
     Device  10  and/or external equipment  130  may, if desired, adjust which electrodes are being used to handle capacitively coupled near field communications signals in real time. If, for example, a receiving electrode array in external equipment  130  or device  10  detects cross-talk between channels, the receiving electrode array can be reconfigured (e.g., to drop certain electrodes and to switch new electrodes into use in place of the dropped electrodes, to reconfigure the size and shape of electrodes that are formed from groups of conductive elements such as pixels in a fingerprint sensor array, etc.). 
     The pattern of signals that is transmitted by a set of near field communications electrodes can be used as a virtual fingerprint that, once recognized, can initiate actions by device  10  and/or external equipment  130 . Illustrative steps involved in using near field communications structures such as structures  22  of device  10  or structures  132  of external equipment to activate suitable actions in this way are shown in the flow chart of  FIG. 28 . 
     At step  28 , a near field transmitter may transmit a pattern (i.e., a spatial pattern) of near field communications signals using multiple electrodes. The pattern of transmitted signals may be, for example, a pattern of capacitively coupled signals that is being transmitted by transmitter  24  in device  10  using structures  22  or may be a pattern of capacitively coupled signals that are transmitted by transmitter  134  in external equipment  130  using structures  132 . A corresponding electrode array may be used in receiving and processing the transmitted signals. 
     The electrode structures that are being used to transmit the signals may include multiple electrodes. For example, the electrode structures may include a two dimensional array of electrodes or may include electrodes arranged in other patterns. During the operations of step  28 , the near field communications transmitter may transmit signals using a predetermined pattern of the electrodes in the array. As an example, the near field communications transmitter may transmit signals using the first, fifth, and eight electrodes in a nine electrode (3×3) array (while the remaining electrodes are inactive). As another example, the near field communications transmitter may transmit signals using a checkerboard pattern of electrodes. 
     The particular subset of electrodes that is used to transmit signals from the electrode array may serve as a characteristic (virtual) “fingerprint” (i.e., an identifier). At step  404 , the receiving near field communications transceiver may monitor its electrode array for incoming signals. In particular the near field communications receiver may monitor the pattern of signals that is being received by its electrode array to determine whether or not a particular identifier is being transmitted. Control circuitry in the receiving device may analyze received signals and can compare the received pattern of signals to known patterns. If there is no match between the incoming pattern of near field communications signals and the predetermined pattern or patterns of signals that are maintained by the receiver, the receiving device can continue to monitor its near field communications array for additional incoming signal patterns, as indicated by line  402 . 
     In response to detection of a match between the measured signal pattern on the near field communications electrode array and a predetermined pattern, appropriate action may be taken using the control circuitry of the receiving device (step  404 ). If there is one predetermined pattern being used, a predetermined action can be taken upon receive of the predetermined pattern. If there are multiple predetermined patterns, the action that is taken may be selected based on the detected pattern. 
     Examples of actions that can be taken in response to detecting a predetermined electrode pattern “fingerprint” include activating a data transfer mode between device  10  and equipment  130 , performing operations associated with authenticating a particular user to a system (e.g., performing a user logon to a system, verifying the identify of a user, using the pattern to retrieve a username or other information associated with a user), launching a particular application, presenting a user with a particular option in connection with a point-of-sale purchase or other transaction, etc. 
     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: 20120301
Publication Date: 20170425
Grant Date: 20170425
Priority Date: 20120301
Inventors: POPE BENJAMIN J.
JARVIS DANIEL W.
MERZ NICHOLAS G. L.
MYERS SCOTT A.
Assignee: APPLE INC
CPC Classifications: [{"code": "G06V40/13", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06V40/13", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B5/0012", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B5/0075", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06K9/00013", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06V40/1306", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0446", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0446", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0416", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0416", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B5/22", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B5/22", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B5/24", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B5/24", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06V40/1306", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B5/22", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B5/24", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0416", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0446", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 47844497