US20160321493A1 - Electronic Device With Shared Near Field Communications and Sensor Structures - Google Patents

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.

Description

• This application is a division of U.S. patent application Ser. No. 13/409,615, filed Mar. 1, 2012, which is hereby incorporated by reference herein in its entirety. This application claims the benefit of and claims priority to U.S. patent application Ser. No. 13/409,615, filed Mar. 1, 2012.
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 inFIGS. 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 ofFIG. 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 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 ofFIG. 13 following insertion of the device into the cradle ofFIG. 13 in accordance with an embodiment of the present invention.
• FIG. 15 is a cross-sectional side view of the electronic device ofFIGS. 13 and 14 following insertion of the device into the cradle ofFIGS. 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 inFIG. 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 inFIG. 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 aselectronic device10 ofFIG. 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 device10 may be a portable electronic device or other suitable electronic device. For example,electronic device10 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.Device10 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.
• Device10 may include a housing such ashousing12.Housing12, which may sometimes be referred to as a case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of these materials. In some situations, parts ofhousing12 may be formed from dielectric or other low-conductivity material. In other situations,housing12 or at least some of the structures that make uphousing12 may be formed from metal elements.
• Device10 may, if desired, have a display such asdisplay14.Display14 may, for example, be a touch screen that incorporates capacitive touch electrodes.Display14 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 ofdisplay14. Buttons such asbutton19 may pass through openings in the display cover layer. The display cover layer may also have other openings such as an opening forspeaker port26.
• Display14 may have an active region and an inactive region. For example,display14 may have an active region such as centralrectangular region17.Active region17 may be bounded byrectangular periphery13 and may be surrounded by an inactive region such as rectangular ring-shapedinactive region15.Active region17 may contain active display pixels for displaying images for a user ofdevice10.Inactive region15 may be free of active image pixels. An opaque masking layer may be provided on the underside of the display cover layer fordisplay14 inregion15 to help hide internal components indevice10 from view by a user ofdevice10. If desired,display14 may be implemented using a borderless design and/or using display structures that cover some or all of the sidewalls and/or other surfaces ofdevice10. The configuration ofFIG. 1 is merely illustrative.
• Housing12 may have openings such asopenings21,23, and25. Openings such asopening23 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 asopenings21 and25 may be used to accommodate electrical components such as audio components or other electrical devices.Opening21 may, for example, form a microphone port andopening25 may form a speaker port. Other portions ofhousing12 such as other sidewall portions or other portions of the front or rear planar surface ofdevice12 may also be provided with structures to accommodate components.
• Device10 may have a front face (e.g., the front surface covered bydisplay14 in the example ofFIG. 1), an opposing rear face (e.g., a rear housing wall in housing12), and sidewall structures such assidewall structures16 of housing12 (as an example). Sensors fordevice10 may be incorporated into components such asbutton19, may be formed on parts of the front face ofdevice10 such asregion27 ininactive area15, in part ofactive area17, on sidewall areas such asregion29, on the rear ofdevice10, or on other suitable portions ofdevice10.
• 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 forelectronic device10 is shown inFIG. 2. As shown inFIG. 2,electronic device10 may wirelessly communicate with external equipment130 (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 body138) to supplydevice10 with user input. For example, a user's finger may be used to supply a touch command or fingerprint todevice10 to control the operation ofdevice10.
• As shown inFIG. 2,electronic device10 may include storage andprocessing circuitry28. Storage andprocessing circuitry28 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 andprocessing circuitry28 may be used to control the operation ofdevice10. 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 andprocessing circuitry28 may be used to run software ondevice10, 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 andprocessing circuitry28 may be used in implementing communications protocols. Communications protocols that may be implemented using storage andprocessing circuitry28 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.
• Circuitry28 may be configured to control the operation of sensors and to take suitable actions based on sensor data and other input. For example,circuitry28 may gather input from a fingerprint sensor, a touch sensor, or other sensor components and may use this gathered input in controlling the operation ofdevice10.
• Input-output circuitry30 may be used to allow data to be supplied todevice10 and to allow data to be provided fromdevice10 to external devices. Input-output circuitry30 may include input-output devices32. Input-output devices32 may include touch screens, buttons, joysticks, click wheels, scrolling wheels, touch pads, key pads, keyboards, microphones, speakers, tone generators, vibrators, cameras,sensor circuitry44 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 ofdevice10 by supplying commands through input-output devices32 and may receive status information and other output fromdevice10 using the output resources of input-output devices32.
• Wireless communications circuitry34 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 circuitry34 may include satellite navigation system receiver circuitry such as Global Positioning System (GPS) receiver circuitry35 (e.g., for receiving satellite positioning signals at 1575 MHz) or satellite navigation system receiver circuitry associated with other satellite navigation systems.Transceiver circuitry36 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).Circuitry34 may use cellulartelephone transceiver circuitry38 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 circuitry34 can include circuitry for other short-range and long-range wireless links if desired. For example,wireless communications circuitry34 may include wireless circuitry for receiving radio and television signals, paging circuits, etc.Transceiver circuitry24 may be used in performing near field communications operations (e.g., using capacitively coupled or inductive near field communications structures). Transceiver circuitry such astransceiver circuitry24 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 circuitry34 may include one ormore antennas40.Antennas40 may be formed using any suitable antenna types. For example,antennas40 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,device10 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 insensor circuitry44. For example, some of the conductive structures insensor circuitry44 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 fieldcommunications transceiver circuitry24.
• 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 inFIG. 3. As shown inFIG. 3,sensor circuitry214 may includeelectrode structures202.Electrode structures202 may include a ring-shaped electrode such aselectrode204 that surrounds an array (e.g., a one-dimensional array) of electrodes such aselectrodes206.Electrodes206 may be coupled tosensor circuitry200 using respective signal lines208.
• Sensor circuitry200 may contain a signal source such assignal source210. During operation, a user may swipe a finger acrosselectrode204 andarray206A of electrodes206 (e.g., a user may move a fingertip downwards acrosselectrodes204 and206). During finger swiping, signalsource210 may drive an alternating current signal (e.g., a signal from 1 to 5 MHz or other suitable frequency) intoelectrode204. This drive signal may be coupled into the user's finger fromelectrode204 when the user's finger is placed over electrode204 (i.e., due to the contact of the user's finger with at least some ofelectrode204 or due to the close proximity of the finger toelectrode204 in scenarios in which electrode204 and the user's finger are separated by an air gap or a layer of plastic, glass, or other dielectric). Eachsignal line208 may be coupled between arespective electrode206 and a corresponding sensor circuit insensor circuitry200. The magnitude of the drive signal that is coupled to each ofelectrodes206 from the user's finger may be measured by monitoring the signals onlines208. As fingerprint ridges pass overelectrodes206, different amounts of signal are coupled intoelectrodes206 from the finger. By providing a sufficientlydense array206A ofelectrodes206 in sensor structures202 (e.g., 1 or more per mm, 10 or more per mm, or 100 or more per mm),sensor circuitry214 may be used to capture a digital representation of the user's fingerprint.
• If desired, fingerprint sensors fordevice10 may be formed using a two-dimensional array of electrodes. Consider, as an example,illustrative sensor circuitry214 ofFIG. 4. As shown inFIG. 4,sensor circuitry214 may includeelectrode structures202 such asouter ring electrode204 and a two-dimensional array206A ofelectrodes206.Array206A may, as an example, include 90-100 rows and 90-100 columns ofelectrodes206. Other numbers of electrodes and other array shapes may be used insensor circuitry214 if desired. For example,array206A may include 100 ormore electrodes206, 500 ormore electrodes206, 1000 ormore electrodes206, 5000 or more electrodes, or other suitable number of electrodes.Outer electrode204 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 ofFIGS. 3 and 4 may, if desired, be incorporated into parts ofdevice10 such asbutton19, portions ofdisplay14 such asregion27 or part ofactive region17, edge portions ofdevice10 such asregion29, etc. In the example ofFIG. 4, a fingerprint sensor has been formed as part ofbutton19.
• FIG. 5 is a cross-sectional side view of a button such asbutton19 ofFIG. 4 in whichfingerprint sensor circuitry214 has been formed. As shown inFIG. 5,button19 may be formed from a button member such asbutton member218.Button member218 may be received within an opening indisplay cover layer216 indisplay14 and may move up and down invertical dimension230. When pressed downwards,button member218 may compressdome switch228 onsupport structure226, thereby closingswitch228. When released,dome switch228 or other biasing structures may forcebutton member218 to move upwardly towards its original position. Control circuitry28 (FIG. 2) may sense whenswitch228 is closed and whenswitch228 is open and can take suitable action.
• Fingerprint sensor214 may include an array of sensor electrodes such asarray206A ofelectrodes206.Array206A may be, for example, a rectangular array such asarray206A ofFIG. 4. Ring-shapedelectrode204 may be a circular ring or a ring of other suitable shape that surroundselectrode array206A.
• Electrodes204 and206 may be formed on a substrate such as substrate220 (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).Member218 may be formed from glass, plastic, ceramic, or other suitable dielectric materials.Substrate220 may be attached to the underside ofmember218, may be embedded within member218 (e.g., by laminatingsubstrate220 between other layers, using insert molding, or using other suitable fabrication techniques). Conductive traces208 may be used to route signals from the electrodes to associated sensor circuitry such as sensor circuitry200 (e.g., via a cable with wires, using a flexible printed circuit cable such ascable224, etc.).
• If desired, an array of sensor electrodes for a fingerprint sensor or a capacitive touch sensor may be formed on an edge portion ofdevice10 such as edge portion29 (FIG. 1).FIG. 6 is a perspective view of an edge portion ofhousing12 ofdevice10 showing howelectrodes206′ may be formed in two or more rows and two or more columns along the edge ofdevice10 such asedge portion29. A sensor formed usingelectrodes206′ ofFIG. 6 may be used for capturing a user's fingerprint and/or for serving as a touch sensor that receives user input to control the operation of device10 (e.g., a touch sensor that receives commands thatdirect device10 to scroll through content ondisplay14, a touch sensor that receives gesture input, or other suitable touch sensor).
• In the illustrative configuration ofFIG. 7,electrodes206′ have been configured to form a one-dimensional array that runs parallel to the edge ofdevice10. As withelectrode structures202 ofFIGS. 3 and 4,electrodes206′ ofFIGS. 6 and 7 may, if desired, be configured to form a sensor such as a fingerprint sensor. Electrodes such aselectrodes206′,206, and204 may also be configured to form capacitive touch sensor electrodes. Electrodes in regions ofdevice10 such asbutton19,region27 ofinactive display area15,active region17,edge region29, or other regions ofdevice10 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 fordevice10 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 bydevice10 to communicate withexternal equipment130 is shown inFIG. 8. As shown inFIG. 8,device10 may have capacitor electrodes such aselectrodes230 and232.Mediator242 may be a human body or part of a human body, air or other dielectrics, conductive materials, or other interposed material betweendevice10 andexternal equipment130. External equipment may have capacitor electrodes such aselectrodes244 and246. Electrodes such aselectrodes230 and246 may be coupled via an imaginary short. During transmission fromdevice10 toequipment130,electrode232 may induce changes in charge on the adjacent portion ofmediator242, which results in corresponding induced charge changes on the far side ofmediator242 andelectrode244. During transmission fromequipment130 todevice10,electrode244 may induce changes in the charge on the portion ofmediator242 that is adjacent to electrode244 that likewise result in changes in the signal onelectrode232.
• Near field transceiver circuitry (e.g.,transceiver circuitry24 ofFIG. 2) may include a near field transmitter such astransmitter234 and a near field receiver such asnear field receiver236.Transmitter234 may supply differential output signals onoutput paths238 and240, respectively. These output signals may be supplied tocapacitor electrodes230 and232. During signal reception operations, signals fromcapacitor electrodes230 and232 may be received onpaths238 and240 bydifferential receiver236.
• External equipment130 may have nearfield transceiver circuitry134 including a transmitter such astransmitter248 for driving output signals ontoelectrodes244 and246 viapaths252 and254, respectively and including a receiver such asreceiver250 for receiving signals fromelectrodes244 and246 viapaths252 and254, respectively.
• During operation, capacitively coupled signals from the near field transmitter indevice10 may pass throughmediator242 to reach the near field receiver inexternal equipment130. When it is desired to convey signals fromexternal equipment130 todevice10, the near field transmitter inexternal equipment130 may transmit signals that pass throughmediator242 to the near field receiver indevice10. In free space near field coupling scenarios,mediator242 may be primarily made up of air. In body coupled communications scenarios,mediator242 may be all or part of the user's body.
• Electrodes indevice10 such aselectrodes232 and230 may be formed from conductive structures in device components. For example, one or more capacitor electrodes indevice10 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 inFIG. 8 may be, for example, one or more capacitive touch sensor electrodes in a touch sensor (see, e.g.,electrodes206′ in a touch sensor on the edge ofdevice10, touch sensor electrodes indisplay14, 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 aselectrodes206 and204), or other electrode structures.External equipment130 may be an electronic accessory, a point of sale terminal, a computer, or other external equipment.Capacitor electrodes244 and246 may be formed from metal plates or other suitable conductive structures. If desired, the shapes ofelectrodes230,232,244, and246 may be configured to enhance capacitive coupling. For example,electrode244 may be configured to have a ring shape that matches a ring shape used forelectrode232.
• An illustrative inductive coupling near field communications arrangement that may be used bydevice10 to communicate withexternal equipment130 is shown inFIG. 9. As shown inFIG. 9,device10 may have inductive structures such asinductor260.Inductor260 may have a pair of terminals coupled topaths238 and240, respectively.Inductor260 may be used to convey wireless signals through the air (or other medium). When transmitting, signals frominductor260 may be received byinductor262 inexternal equipment130. Whenexternal equipment130 is transmitting wireless signals withinductor262,inductor260 indevice10 may be used in receiving the transmitted signals.
• Nearfield transceiver circuitry24 indevice10 may include a near field transmitter such astransmitter234 and a near field receiver such asnear field receiver236.Transmitter234 may supply differential output signals onoutput paths238 and240, respectively. These output signals may be supplied to the terminals ofinductor260. During signal reception operations, signals frominductor260 may be received onpaths238 and240 bydifferential receiver236.
• External equipment130 may have near field transceiver circuitry that includes a transmitter such astransmitter248 for driving output signals throughinductor262 viapaths252 and254, respectively and that includes a receiver such asreceiver250 for receiving signals frominductor262 viapaths252 and254, respectively.
• During operation, inductively coupled signals from the near field transmitter indevice10 may be wirelessly conveyed to the near field receiver inexternal equipment130. When it is desired to convey signals fromexternal equipment130 todevice10, the near field transmitter inexternal equipment130 may transmitsignals using inductor262 that are received byinductor260 indevice10.
• Inductive structures such asinductor260 indevice10 may be formed from conductive structures in device components. For example, one or more inductive structures in device10 (e.g., inductor260) 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 inFIG. 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 equipment130 ofFIG. 9 may be an electronic accessory, a point of sale terminal, a computer, or other external equipment.
• FIG. 10 is a diagram showing howdevice10 may have structures such as sensor/NFC structures22 that are used both as near field communications elements (e.g., capacitor plates such aselectrode230 and/orelectrode232 or parts of such conductive capacitor structures) and inductive elements (e.g.,inductor260 or part of inductor260) 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 inFIG. 10,device10 may use sensor/NFC structures22 to receive input from an external object such as a user's finger (finger138 ofFIG. 10) and may communicate wirelessly (see, e.g., wireless signal128) with external equipment using near field communications. With this type of arrangement,sensor circuitry44 andnear field transceiver24 may sharestructures22 indevice10, reducing component count and helping to ensure that nearfield communications structures22 are well placed on device10 (i.e., so that near field communications structures are not blocked by portions of a conductive housing or conductive device structures).
• Device10 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 equipment130 may be a peer device (e.g., a device such asdevice10 that is operated by another user), a device accessory (e.g., a cradle that can receivedevice10, 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,device10 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 ofdevice10 may placedevice10 near to a point of sale terminal when it is desired to make a wireless payment, may placedevice10 near a door lock when it is desired to obtain access to a building, may placedevice10 near a security card reader when it is desired to authenticate to a computer system, and may placedevice10 near to an audio device when it is desired to communicate with the audio device using near field communications.
• As shown inFIG. 10,electronic device10 andexternal equipment130 may includecontrol circuitry28 and136, respectively.Control circuitry28 and136 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.
• Device10 andexternal equipment130 may also include transceiver circuitry such astransceiver circuitry24 and134, respectively.Transceiver circuitry24 and134 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,device10 includes a transmitter (i.e.,transceiver24 may be a transmitter) andequipment130 includes a corresponding receiver (i.e.,transceiver134 may be a receiver). This type of arrangement may be used to support unidirectional near field communications betweendevice10 anexternal equipment130. If desired, bidirectional near field communications may be supported. For example,transceiver24 may include a transmitter and a receiver andtransceiver circuitry134 may include a transmitter and a receiver. Wireless near field communications signals128 may, in general, be communicated fromdevice10 toequipment130, fromequipment130 todevice10, or both fromdevice10 toequipment130 and fromequipment130 todevice10.
• Device10 may includestructures22.Structures22 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.Structures132 may include near field communications structures such as capacitors or inductors that are configured to communicate withstructures22 using near field communications.
• The structures ofelements22 and132 are capable of transmitting and/or receiving near-field-coupled radio-frequency electromagnetic fields. When used as a sensor,structures22 andsensor circuitry44 may be used to capture a fingerprint fromfinger138 or to gather touch input fromfinger138 or other external object.
• An illustrative configuration that may be used for sharing sensor/NFCconductive structures22 between near field communications circuitry such as nearfield communications transceiver24 and the circuitry associated with additional components such assensor circuitry44 is shown inFIG. 11. As shown inFIG. 11,device10 may includestructures22 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.Structures22 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).Terminal46 may form a first terminal forstructures22 and terminal48 may form a second terminal forstructures22.
• Circuitry124 may include transceiver circuits such as near fieldcommunications transceiver circuitry24.Transceiver circuitry24 may be used to transmit wireless payment information, media data, streaming data (e.g., whendevice10 has been paired with an audio or video accessory), voice and data associated with a telephone call (e.g., whendevice10 has been paired with audio equipment in an automobile), security card information, wireless lock information, or other information.Circuitry124 may also include other circuitry (i.e., non-NFC circuitry) such assensor circuitry44.Sensor circuitry44 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.
• Circuits24 and44 may be implemented using one or more integrated circuits. For example,circuit24,circuit44, and one or more integrated circuits incontrol circuitry28 may be implemented using separate integrated circuits. If desired,circuit24 and circuit44 (and, optionally one or more control circuits within control circuitry28) may be implemented using a common integrated circuit.
• Circuit40 may be used to couple multiple circuits such as nearfield communications transceiver24 andsensor circuitry44 to sharedstructures22.Circuit40 may, for example, be a passive coupler that allowscircuits24 and44 to operate simultaneously. With this type of arrangement, frequency-based multiplexing may be used to accommodate sharing ofstructures22. As an example, nearfield communications transceiver24 may be configured to operate at a first radio frequency such as 13.56 MHz andsensor circuitry44 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,circuitry40 can be configured to form a frequency-based multiplexing filter that routes signals to and fromstructures22,24, and44 based on their frequency.
• If desired,circuitry40 may be implemented using switching circuitry that selectively couples eithercircuit24 orcircuit44 toterminals46 and48 in response to control signals received fromcontrol circuitry28. This type of arrangement allowscontrol circuitry28 to configurecircuitry40 so that nearfield communications transceiver24 can transmit and/or receive near field communicationssignals using structures22 or to configurecircuitry40 so thatsensor circuitry44 can usestructures22 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.Path50 may be used to convey one or more control signals betweencontrol circuitry28 and switchingcircuitry40. When it is desired to transmit and/or receive NFC signals withNFC transceiver24,control circuitry28 may provide control signals to switchingcircuitry40 viacontrol path50 that direct switchingcircuitry40 to operate in a near field communications (NFC) mode. In the NFC mode,NFC transceiver24 may be coupled tostructures22 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 betweenstructures22 andsensor circuitry44,control circuitry28 may provide control signals to switchingcircuitry40 overpath50 that direct switchingcircuitry40 to operate in a sensor mode (e.g., a fingerprint sensor mode, touch sensor mode, etc.). After placingswitching circuitry40 in the sensor configuration,sensor circuitry44 may be used to process sensor signals from structures22 (e.g., to capture a fingerprint, to gather touch commands, etc.). Becausestructures22 can be used for both near field communications and sensor functions, the hardware resources associated with supporting these operations indevice10 may be minimized. The sharing ofstructures22 between near field communications and sensor functions may also make it easier to mountconductive structures22 at an appropriate location within the potentially compact volume available withindevice10.
• If desired,structures22 may be integrated into a button such asbutton19 ofdevice10. This type of configuration is shown inFIG. 12. As shown inFIG. 12, a user may place a finger such asfinger138 overbutton19 during use ofdevice10.Device10 may use a switch underbutton19 to detect button presses.Device10 may usesensor circuitry44 andstructures22 inbutton19 to capture fingerprints (or other capacitive sensor data). When it is desired to usetransceiver circuitry24 for near field communications,structures22 inbutton19 may be used in transmitting and/or receiving near field communications.
• Usingstructures22 that have been incorporated intoregion27, intoregion29, intobutton19, or other portions indevice10,device10 may communicate with mating near field communications structures (e.g.,structures132 andcircuitry134 ofFIG. 10) when mated with external equipment such asillustrative accessory130 ofFIG. 13.Accessory130 may be, for example, external equipment such as a cradle having an opening such asopening300.Cradle130 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 inFIG. 13,device10 has not yet been inserted intoopening300. In the configuration shown inFIG. 14,device10 has been mated withaccessory130. In particular,device10 has been inserted intoopening300, so that the lower end ofdevice housing12 is surrounded by the sidewalls ofopening300, holdingdevice10 in place onaccessory130. As shown in the cross-sectional side view ofFIG. 15, this allows wireless near field communications signals to be conveyed betweenstructures22 in device10 (e.g.,structures22 inbutton19 and/or a region such asregion27 on a touch screen or inactive portion of a display) and nearfield communications structures132 inequipment130.
• FIG. 16 shows howdevice10 may be held in place (e.g., manually by a user or using support structures) so thatstructures22face structures132 inexternal equipment130. With a configuration of the type shown inFIG. 16,external equipment130 may be a peer device (e.g., another device such as device10), 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.
• Structures22 may include patterned conductive structures. For example,structures22 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 structures22 (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 inFIG. 17. As shown inFIG. 17,structures22 may include multiple electrodes such as electrodes22-1 and22-2. When aligned with corresponding capacitor electrodes in nearfield communications structures132 such as electrodes132-1 and132-2,structures22 and132 may be used to support parallel near field communications (e.g., with one data stream being conveyed between electrodes22-1 and132-1, with one data stream being conveyed between electrodes22-2 and132-2, etc.). Any suitable number of electrodes instructures22 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 circuitry40 (FIG. 11) may be used in selecting which electrodes instructures22 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 alignstructure22 sufficiently withstructures132 to support parallel communications using all available electrodes. In this type of situation,device10 can automatically select a subset of electrodes for use in performing near field communications.FIG. 18 is a top view ofstructures22 andstructures132 in a configuration in which only a subset of the available electrodes instructures22 and132 overlap (i.e., only electrodes22-1 and132-1). In this illustrative arrangement, only electrodes22-1 and132-1 participate in supporting near field communications. When more overlapping electrodes become available, switchingcircuitry40 may be used to automatically switch additional electrodes into use.
• As shown inFIG. 19,structures22 may be configured to form inductive structures for use in inductively coupled near field communications. In the illustrative configuration ofFIG. 19,structures22 include an array of electrodes such as electrode array206 (e.g., for a fingerprint sensor) and include a surrounding ring of conductive material such as ring204 (e.g., a conductive ring such asmetal ring204 ofFIG. 4).Ring204 may be provided with a gap such asgap302. Terminals such asterminals46 and48 may be formed on opposing sides ofgap302. With this type of configuration,electrode204 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-shapedelectrode204 may be provided with an undulating shape. The undulating shape ofFIG. 20 may help enhance near field coupling performance.
• In the illustrative configuration ofFIG. 21,electrode204 has been provided with multiple turns, thereby increasing the inductance of structures22 (i.e., inductor204) for use in inductively coupled near field communications. In the examples ofFIGS. 19, 20, and 21,structures22 include an array ofelectrodes206A (e.g., for a fingerprint sensor).
• In general, any suitable conductive structures22 (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 ofFIGS. 19, 20, and 21 are merely illustrative.
• If desired,structures22 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 allowdevice10 to wirelessly communicate withexternal equipment130.
• FIGS. 22 and 23 are cross-sectional side views of optical structures304 of the type that may be used in both short-range optical communications and in sensing operations fordevice10.
• In the arrangement shown inFIG. 22, a user has placed an external object such asfinger138 in the vicinity ofoptical structures306.Optical structures306 may include optical transmitters such astransmitters306T and optical receivers such asreceivers306R.Transmitters306T may be, for example, infrared or visible light sources such as light-emitting diodes or lasers.Receivers306R may be, for example, infrared or visible light receivers such as photodiodes or phototransistors. In the configuration ofFIG. 22,structures306 are being used as a fingerprint sensor. There may be, for example, an array having numerous rows and columns of transmitters and receivers. Eachtransmitter306T may transmit light and eachreceiver306R may measure that amount of transmitted light that is reflected from the surface offinger138. Reflected light intensity is influenced by the pattern of surface features onfinger138, so the configuration ofFIG. 22 may be used as an optical fingerprint sensor that captures a digital fingerprint fromfinger138.
• When it is desired to usestructures306 to support optical communications withexternal equipment130,device10 may be aligned withexternal equipment130, as shown inFIG. 23.Device10 may, as an example, be held in place by a user so thatoptical structures306 align with correspondingoptical structures308 inexternal equipment130. As shown inFIG. 23,optical structures308 may include one or moreoptical transmitters308T and one or moreoptical receivers308R. When aligned as shown inFIG. 23,transmitters306T can transmit light310 that is received byreceivers308R andtransmitters308T may transmit light312 that is received byreceivers306R. In configurations with only a single receiver/transmitter pair,structures306 and308 may support unidirectional communications. In configurations with multiple transmitters and receivers,structures306 and308 may support bidirectional communications. Whenstructures306 and308 each contain multiple transmitters and receivers, multiple parallel data streams may be conveyed in parallel betweendevice10 andexternal equipment130, 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 inFIGS. 24 and 25. As shown inFIG. 24,optical structures306 may include an optical source such assource306T and an array ofreceivers306R (e.g., a one-dimensional or two-dimensional array having tens, hundreds, or thousands ofreceivers306R).Optical source306T may be, for example, a light-emitting diode, a light-emitting diode array, one or more laser diodes, or other light source.Light source306T may launch light321 intoedge328 oflight guide structure332.Light321 may be guided withinlight guide structure332 by total internal reflection fromupper surface320 andlower surface322, as illustrated by reflectedlight326. Some of light326 may escape vertically upwards to illuminatefinger138.Light detectors306R may then measure the intensity of reflected light from finger138 (e.g., to capture an optical fingerprint image).
• Light guide structures332 may be formed from a planar optically transparent member such as a sheet of plastic or glass or a transparent coating on a substrate.Structures332 may have a portion such asportion330 that helpsdirect light326 upwards in a localized area.
• As shown inFIG. 25, when it is desired to communicate optically betweendevice10 andexternal equipment130,device10 and external equipment may be placed sufficiently close to each other to alignoptical structures308 inexternal equipment130 andoptical structures306 indevice10. For example,portion330 oflight guide plate332 may be aligned withreceiver308R ofoptical structures308, so thatportion326′ of light326 fromlight source306T can be detected bylight receiver308R.Optical structures308 may include a light source such aslight transmitter308T for transmitting light340 to one or more ofreceivers306R such asreceiver306R′ inoptical structures306 ofdevice10. Whendevice10 desires to optically transmit information toexternal equipment130,control circuitry28 can use transceiver circuitry (e.g.,transceiver circuitry24 ofFIG. 2) to modulate the output oflight source306T, thereby transmitting data vialight326′ toreceiver308R inexternal equipment130.External equipment130 may optically transmit information todevice10 by modulating the output oflight source308T, thereby transmitting data via light340 that can be detected byreceiver306R′.
• Optical structures such asstructures306 indevice10 may be formed as part of a button such asbutton19, may be formed in regions such asregions27 and29 ofFIG. 1, or may be formed elsewhere onhousing12. Optical structures such asstructures308 may be formed in an opening such asopening300 of a cradle such ascradle130 ofFIGS. 13, 14, and 15, or may be formed elsewhere inexternal equipment130.Optical structures306 may include an array of receivers such asreceivers306R 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 ofoptical structures306 to form an optical fingerprint sensor (in fingerprint sensor mode) and to form structures for supporting optical communications with nearby external equipment130 (e.g., a cradle or other accessory, a peer device such asdevice10, or other external equipment) is merely illustrative.
• In configurations fordevice10 in which sensor/NFC structures22 are being used to support capacitive near field communications withexternal equipment130, it may be challenging to properly align one or more of the electrodes instructures22 with corresponding electrode structures in nearfield communications structures132 ofexternal equipment130. For example, a user may find it difficult to holdbutton19 andstructures22 onbutton19 in precise alignment withcorresponding structures132 on equipment130 (e.g., due to hand movement, etc.). There may also be an air gap betweenstructures22 and132 that can cause electromagnetic fields to spread and weaken, potentially disrupting effective near field communications. To ensure satisfactory performance under conditions such as these,structures132 may be provided with enlarged dimensions relative tostructures22. If, as an example, there is one electrode instructures22 such as ring-shapedelectrode204 ofFIG. 26,structures132 may be provided with a mating electrode such aselectrode132′ that has larger lateral (X and Y) dimensions than the dimensions ofelectrode204.
• In theFIG. 26 example,electrode204 ofstructures22 has a ring shape andcorresponding electrode132′ ofstructures132 has a larger (wider) ring shape. Instructures22 with one or more electrodes with different shapes,structures132 may be provided with one or more correspondingly enlarged electrodes with different shapes. If, for example,structures22 include two rectangular electrodes that are used to support capacitively coupled near field communications such aselectrodes22A and22B ofFIG. 27,structures132 may be provided with two corresponding rectangular electrodes such as electrodes132-1 and132-2. Electrodes132-1 and132-2 may be larger in area thanelectrodes22A and22B to enhance capacitive coupling.
• The larger areas of the electrode(s) instructures132 relative to the electrode(s) instructures22 may therefore help ensure satisfactory near field communications performance, even whenstructures22 and132 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.
• Device10 and/orexternal equipment130 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 inexternal equipment130 ordevice10 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 bydevice10 and/orexternal equipment130. Illustrative steps involved in using near field communications structures such asstructures22 ofdevice10 orstructures132 of external equipment to activate suitable actions in this way are shown in the flow chart ofFIG. 28.
• Atstep28, 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 bytransmitter24 indevice10 usingstructures22 or may be a pattern of capacitively coupled signals that are transmitted bytransmitter134 inexternal equipment130 usingstructures132. 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 ofstep28, 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). Atstep404, 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 byline402.
• 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 (step404). 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 betweendevice10 andequipment130, 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.

Claims (20)

What is claimed is:

1. An electronic device configured to communicate with external equipment and configured to gather user input, the electronic device comprising:

a user input sensor having an array of transmitters and receivers that communicates with a corresponding array of transmitters and receivers in the external equipment; and

control circuitry coupled to the array of transmitters and receivers in the user input sensor, wherein the control circuitry is configured to gather the user input using the receivers in the array, is configured to transmit data to the external equipment using the transmitters in the array, and is configured to receive data from the external equipment using the receivers in the array.

2. The electronic device defined inclaim 1, wherein the array of transmitters and receivers comprises an array of electrodes, and wherein each of the electrodes transmits data to the external equipment and receives data from the external equipment.

3. The electronic device defined inclaim 2, wherein each of the electrodes comprises a capacitive electrode that forms a portion of a touch sensor that gathers the user input.

4. The electronic device defined inclaim 3, the electronic device further comprising:

a display; and

an additional array of capacitive electrodes that form an additional touch sensor that overlaps the display, wherein the touch sensor and the display do not overlap.

5. The electronic device defined inclaim 4, wherein the touch sensor comprises a fingerprint sensor.

6. The electronic device defined inclaim 2, wherein the corresponding array of transmitters and receivers in the external equipment comprises an array of mating electrodes, wherein each mating electrode forms a mating electrode pair with a corresponding one of the electrodes in the electronic device.

7. The electronic device defined inclaim 6, wherein each mating electrode pair transmits a data stream between the mating electrode and the electrode in parallel with each of the other mating electrode pairs.

8. The electronic device defined inclaim 7, further comprising:

switching circuitry coupled to each of the electrodes in the array of electrodes in the electronic device, wherein the switching circuitry selects which of the mating electrode pairs transmit data streams.

9. The electronic device defined inclaim 8, wherein the electronic device detects a signal strength of the data stream between the mating electrode and the electrode in each of the mating electrode pairs, and wherein the switching circuitry selects whether a given mating electrode pair transmits the data stream based on the signal strength for the given pair.

10. The electronic device defined inclaim 8, wherein only a subset of the electrodes and the mating electrodes transmit data streams when the electrode and the mating electrode of at least one mating electrode pair are misaligned.

11. The electronic device defined inclaim 10, wherein the switching circuitry automatically begins transmitting a data stream between an additional electrode and an additional mating electrode when the additional electrode and the additional mating electrode become aligned.

12. An electronic device that communicates wirelessly with an electronic device accessory and that gathers user touch input, the electronic device comprising:

an array of electrodes that communicates wirelessly with a corresponding array of electrodes in the electronic device accessory;

wireless communications circuitry coupled to the array of electrodes, wherein the wireless communications circuitry transmits data to the corresponding array of electrodes in the electronic device accessory using the array of electrodes and receives data from the corresponding array of electrodes in the electronic device accessory using the array of electrodes; and

input-output circuitry coupled to the array of electrodes, wherein the input-output circuitry gathers the user touch input using the array of electrodes.

13. The electronic device defined inclaim 12, wherein the electrodes comprise capacitive electrodes that form a capacitive touch sensor, and wherein the input-output circuitry gathers the user touch input using the capacitive touch sensor.

14. The electronic device defined inclaim 12, wherein the electronic device accessory comprises an electronic device cradle having an opening that receives the electronic device, and wherein the array of electrodes in the electronic device and the corresponding array of electrodes in the electronic device accessory overlap when the electronic device is received in the opening.

15. The electronic device defined inclaim 12, wherein the electronic device uses selected electrodes in the array of electrodes to transmit a pattern of signals to the electronic device accessory.

16. The electronic device defined inclaim 12, wherein in response to receiving a pattern of signals from the electronic device accessory, the electronic device compares the received pattern of signals to a plurality of known patterns of signals.

17. The electronic device defined inclaim 16 wherein the electronic device takes a predetermined action in response to the received pattern of signals matching one of the plurality of known patterns of signals.

18. A method of communicating between a first device and a second device, comprising:

receiving a predetermined spatial pattern of near field communications signals from an array of electrodes in the first device using an array of electrodes in the second device; and

in response to receiving the predetermined spatial pattern of near field communications signals using the array of electrodes in the second device, taking a corresponding action with the second device.

19. The method defined inclaim 18 wherein taking the corresponding action comprises initiating a data transfer mode between the first and second devices.

20. The method defined inclaim 18, further comprising:

detecting cross-talk between a first mating electrode pair and a second mating electrode pair, wherein each of the first and second mating electrode pairs comprises an electrode from the array of electrodes in the first electronic device and an electrode from the array of electrodes in the second electronic device; and

discontinuing near-field communications between at least one of the first and second mating electrode pairs in response to detecting the cross-talk.

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