PATENT DOCUMENT

Publication Number: US-10496192-B2
Application Number: US-201815906937-A
Country: US
Kind Code: B2

Title: Computer stylus having integrated antenna and sensor structures

Abstract:
A computer stylus may be provided that includes an elongated body with a tip and an opposing end coupled together by a shaft that includes a metal tube. The stylus may include a substrate at the end of the elongated body and conductive traces on the substrate. The traces may form a sensor electrode for a sensor and an antenna resonating element for an antenna in the stylus. The sensor may include an electrode that gathers sensor signals. Control circuitry may wirelessly transmit the sensor signals to external equipment using the antenna. The sensor electrode may be coupled to the metal tube by a filter. The filter may form an open circuit at radio-frequencies and a short circuit at the frequency of the sensor signals. The filter may mitigate deterioration in wireless performance of the antenna associated with the presence of the sensor.

Claims:
What is claimed is: 
     
       1. A computer stylus, comprising:
 an elongated body having a tip and an opposing end coupled by a shaft that extends along a longitudinal axis; 
 a dielectric substrate at the end of the elongated body; 
 conductive traces on the dielectric substrate, wherein the conductive traces form part of a sensor and part of an antenna for the computer stylus, wherein the conductive traces comprise a sensor electrode for the sensor; and 
 a metal tube that forms at least part of the shaft, wherein the sensor has a sensor leg that couples the sensor electrode to the metal tube. 
 
     
     
       2. The computer stylus defined in  claim 1 , wherein the conductive traces comprise and an antenna resonating element for the antenna. 
     
     
       3. The computer stylus defined in  claim 2  wherein the sensor leg is coupled to the metal tube through a filter. 
     
     
       4. The computer stylus defined in  claim 3 , wherein the antenna is configured to transmit radio-frequency signals at a first frequency that is greater than 600 MHz, the sensor is configured to generate sensor signals at a second frequency that is less than 600 MHz, the filter is configured to form an open circuit between the sensor electrode and the metal tube at the first frequency, and the filter is configured to form a short circuit between the sensor electrode and the metal tube at the second frequency. 
     
     
       5. The computer stylus defined in  claim 4 , wherein the filter comprises a choke inductor. 
     
     
       6. The computer stylus defined in  claim 3 , wherein the metal tube forms a ground for the antenna, the antenna resonating element comprising an antenna resonating element arm and a return path coupled between the antenna resonating element arm and the metal tube. 
     
     
       7. The computer stylus defined in  claim 6 , wherein the conductive traces comprise an additional sensor leg coupled to the sensor electrode, the electronic device further comprising:
 an additional filter coupled between the additional sensor leg and the metal tube. 
 
     
     
       8. The computer stylus defined in  claim 7 , wherein the antenna resonating element arm extends between the sensor leg and the additional sensor leg and comprises a bend. 
     
     
       9. The computer stylus defined in  claim 6 , wherein the sensor electrode is shorted to the antenna resonating element arm through a segment of the conductive traces, the antenna resonating element comprising the segment of the conductive traces and a portion of the sensor electrode. 
     
     
       10. The computer stylus defined in  claim 6  further comprising a flexible printed circuit on the substrate, wherein the sensor electrode is formed on the flexible printed circuit, a portion of the sensor electrode overlaps the antenna resonating element arm, and the flexible printed circuit has an end that is interposed between the portion of the sensor electrode and the antenna resonating element arm. 
     
     
       11. The computer stylus defined in  claim 10 , wherein the antenna resonating element arm is capacitively coupled to the portion of the sensor electrode and the antenna resonating element comprises the portion of the sensor electrode. 
     
     
       12. The computer stylus defined in  claim 6 , wherein the conductive traces further comprise a grid of driver and receiver lines for the sensor and the sensor electrode comprises a loop-shaped grounded electrode that surrounds the grid of driver and receiver lines. 
     
     
       13. The computer stylus defined in  claim 12 , wherein the loop-shaped grounded electrode comprises a first terminal coupled to the antenna resonating element arm and a second terminal coupled to the metal tube through the filter. 
     
     
       14. The computer stylus defined in  claim 1 , wherein the sensor comprises a sensor selected from the group consisting of: a proximity sensor, a touch sensor, and a force sensor. 
     
     
       15. A computer stylus comprising:
 an elongated body having a tip and an opposing end coupled by a shaft, wherein the shaft extends along a longitudinal axis, has a circumference, and includes a metal tube; 
 a dielectric support structure at the end of the elongated body; 
 a sensor that includes a conductive structure on the dielectric support structure, a sensor leg extending from the conductive structure, and a filter coupled between the sensor leg and the metal tube; and 
 an antenna having an antenna resonating element arm on the dielectric support structure that wraps around at least part of the circumference. 
 
     
     
       16. The computer stylus defined in  claim 15 , wherein the filter comprises a choke inductor coupled between the sensor leg and the metal tube. 
     
     
       17. The computer stylus defined in  claim 15 , wherein the antenna resonating element arm is shorted to the conductive structure. 
     
     
       18. The computer stylus defined in  claim 15 , wherein the sensor comprises an additional sensor leg extending from the conductive structure and an additional filter coupled between the additional sensor leg and the metal tube. 
     
     
       19. The computer stylus defined in  claim 15 , further comprising:
 a flexible printed circuit on the dielectric support structure, wherein the sensor leg and the conductive structure are formed on the flexible printed circuit, a portion of the conductive structure overlaps the antenna resonating element arm, and a portion of the flexible printed circuit is interposed between the portion of the conductive structure and the antenna resonating element arm. 
 
     
     
       20. A computer stylus, comprising:
 an elongated body having a tip and an opposing end coupled by a shaft that extends along a longitudinal axis and that has a circumference, wherein the shaft includes a metal tube and a dielectric outer tube that covers the metal tube; 
 control circuitry in the shaft; 
 a sensor at the end of the elongated body and coupled to the control circuitry over a sensor data path, wherein the sensor comprises a conductive electrode configured to generate a sensor signal, the sensor data path is configured to convey the sensor signal to the control circuitry, and the sensor data path comprises a conductive line that is coupled to the metal tube through a filter; and 
 an antenna having an antenna resonating element arm that is coupled to the metal tube and that is interposed between the metal tube and the conductive electrode, wherein the antenna is configured to convey radio-frequency signals within a frequency band and the filter is configured to isolate the conductive electrode from the metal tube in the frequency band.

Description:
BACKGROUND 
     This relates generally to wireless communications circuitry and, more particularly, to wireless communications circuitry for elongated wireless devices such as computer styluses. 
     It can be challenging to form wireless circuitry for electronic equipment. For example, it can be difficult to incorporate wireless components such as antennas into compact portable devices such as tablet computer styluses. If care is not taken, the presence of conductive structures such as conductive structures in a sensor for the electronic device will adversely affect antenna performance. Poor antenna performance can lead to the use of increased transceiver power and reduced battery life. Poor antenna performance can also degrade wireless functionality. 
     It would therefore be desirable to be able to provide improved wireless circuitry for wireless devices such as computer styluses. 
     SUMMARY 
     A computer stylus may be provided that supplies input to an electronic device such as a tablet computer. The stylus may have an elongated body with a tip and an opposing end coupled together by a shaft. The shaft may include a metal tube. 
     The computer stylus may include a dielectric substrate at the end of the elongated body and conductive traces or other conductive structures on the dielectric substrate. The conductive traces may form part of a sensor and part of an antenna for the computer stylus. For example, the conductive traces may be used to form a sensor electrode for the sensor and an antenna resonating element for the antenna. 
     The sensor may be a touch sensor, proximity sensor, or force sensor, as examples. The sensor may include a sensor electrode that gathers sensor signals at a relatively low frequency. The sensor may convey the sensor signals to control circuitry in the shaft over a sensor data path. The control circuitry may use the antenna to wirelessly transmit the sensor signals to the tablet computer over a wireless link. The sensor data path may include a conductive leg on the substrate that extends from the sensor electrode towards the metal tube. The conductive leg may be coupled to the metal tube by a filter. The filter may include a choke inductor that forms an open circuit at radio-frequencies and that forms a short circuit at the frequency of the sensor signals. The filter may serve to isolate the sensor from radio-frequency signals conveyed by the antenna and may mitigate deterioration in the wireless performance of the antenna associated with the presence of the sensor. 
     Additional conductive legs and filters may be used to couple the sensor electrode to the metal tube. The sensor electrode may be shorted to the antenna resonating element arm to extend the radiating length of the antenna to include portions of the sensor electrode. In another suitable arrangement, the sensor electrode may be formed on a flexible printed circuit that is wrapped around the dielectric substrate. The sensor electrode may include a portion that overlaps the antenna resonating element arm. The flexible printed circuit may have an end that is interposed between the portion of the sensor electrode and the antenna resonating element arm. If desired, the portion of the sensor electrode may be capacitively coupled to the antenna resonating element arm at radio-frequencies so that the portion of the sensor electrode forms a part of the antenna. The sensor and the antenna may both be integrated within the end of the stylus without sacrificing sensor data accuracy or wireless antenna performance. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative computer and associated computer stylus in accordance with an embodiment. 
         FIG. 2  is a schematic diagram of an illustrative stylus with wireless communications circuitry in accordance with an embodiment. 
         FIG. 3  is a diagram of illustrative wireless circuitry for use in a stylus in accordance with an embodiment. 
         FIG. 4  is a diagram of an illustrative inverted-F antenna for a stylus in accordance with an embodiment. 
         FIG. 5  is a perspective view of an illustrative antenna formed using laser direct structuring techniques in accordance with an embodiment. 
         FIG. 6  is a perspective view of an illustrative flexible printed circuit antenna in accordance with an embodiment. 
         FIG. 7  is a perspective view of an illustrative antenna with a metal resonating element mounted to a support structure in accordance with an embodiment. 
         FIG. 8  is a cross-sectional side view of an illustrative antenna formed from printed conductive ink in accordance with an embodiment. 
         FIG. 9  is a cross-sectional side view of a portion of an elongated body for a stylus in accordance with an embodiment. 
         FIG. 10  is a side view of an illustrative stylus having a tip and an opposing end at which an antenna and a sensor have been formed in accordance with an embodiment. 
         FIG. 11  is a perspective view of an illustrative antenna and sensor mounted at the end of a stylus in accordance with an embodiment. 
         FIG. 12  is a perspective view of an illustrative sensor having a pair of conductive legs and an antenna mounted between the pair of conductive legs at the end of a stylus in accordance with an embodiment. 
         FIG. 13  is a perspective view of an illustrative antenna and sensor formed from shared conductive traces at the end of a stylus in accordance with an embodiment. 
         FIG. 14  is a perspective view of an antenna at the end of a stylus and a sensor that overlaps the antenna in accordance with an embodiment. 
         FIG. 15  is a diagram of conductive traces that may be used to form a sensor of the type shown in  FIGS. 11-14  in accordance with an embodiment. 
         FIG. 16  is a graph of antenna performance (antenna efficiency) for an antenna of the type shown in  FIGS. 11-14  in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     A system that includes electronic equipment that communicates wirelessly is shown in  FIG. 1 . The equipment of  FIG. 1  includes electronic device  10  and electronic device  20 . Electronic equipment such as devices  10  and  20  may, in general, be computing devices such as laptop computers, computer monitors containing embedded computers, tablet computers, cellular telephones, media players, or other handheld or portable electronic devices, smaller devices such as wrist-watch devices, pendant devices, headphone or earpiece devices, devices embedded in eyeglasses or other equipment worn on a user&#39;s head, or other wearable or miniature devices, televisions, computer displays that do not contain embedded computers, gaming devices, navigation devices, embedded systems such as a systems in which electronic equipment is mounted in kiosks or automobiles, computer accessories such as touch pads, computer mice, computer styluses, or other electronic accessories, equipment that implements the functionality of two or more of these devices, or other electronic equipment. In the illustrative configuration of  FIG. 1 , which is sometimes described herein as an example, device  20  is a tablet computer or other device with a touch screen and device  10  is a computer stylus. When a drawing program or other software is running on tablet computer  20 , a user can use stylus  10  to draw on tablet computer  20  and to provide other input to tablet computer  20 . 
     Tablet computer  20  may include a housing such as housing  22  in which display  24  is mounted. Input-output devices such as button  26  may be used to supply input to tablet computer  20 . Button  26  may be omitted if desired. Display  24  may be a capacitive touch screen display or a display that includes other types of touch sensor technology. The touch sensor of display  24  may be configured to receive input from stylus  10 . 
     Stylus  10  may have a cylindrical shape or other elongated body that extends along longitudinal axis  12 . The body of stylus  10  may be formed from metal and/or plastic tubes and other elongated structures. Stylus  10  and tablet computer  20  may contain wireless circuitry for supporting wireless communications via wireless communications link  28 . As an example, stylus  10  may supply wireless input to tablet computer  20  via link  28  (e.g., information on settings in a drawing program or other software running on tablet computer  20 , input to select a desired on-screen option, input to supply tablet computer  20  with a touch gesture such as a stylus flick, input to draw a line or other object on display  24 , input to move or otherwise manipulate images displayed on display  24 , etc.). 
     Stylus  10  may have a tip such as tip  14 . Tip  14  may contain a conductive elastomeric member that is detected by the capacitive touch sensor of display  24 . If desired, tip  14  may contain active electronics (e.g., circuitry that transmits signals that are capacitively coupled into the touch sensor of display  24  and that are detected as touch input on the touch sensor). 
     Shaft portion  16  of stylus  10  may couple tip  14  of stylus  10  to opposing end  18  of stylus  10 . End  18  may contain a conductive elastomeric member, active electronics (e.g., circuitry that transmits signals that are capacitively coupled into the touch sensor of display  24  and that are detected as touch input on the touch sensor), buttons, sensor components such as a touch sensor, proximity sensor, or force sensor, or other input-output components. 
     Sensor components at end  18  of stylus  10  may, for example, generate touch or proximity sensor data indicative of whether or not end  18  of stylus  10  is being pressed against display  24  of tablet computer  20 , force sensor data indicative of how hard end  18  of stylus  10  is being pressed against display  24  of tablet computer  20 , etc. Wireless circuitry in stylus  10  may convey this sensor data to tablet computer  20  over link  28 . Tablet computer  20  may change settings in a drawing program or may perform other operations based on the sensor data received from stylus  10 . As one example, tablet computer  20  may use the received sensor data to activate an eraser function associated with a drawing program running on tablet computer  20 , or may perform any other desired operations. 
     If desired, a force sensor may additionally or alternatively be incorporated into tip  14  of stylus  10 . A force sensor in tip  14  may be used to measure how forcefully a user is pressing tip  14  of stylus  10  against the outer surface of display  24 . Force data may then be wirelessly transmitted from stylus  10  to tablet computer  20  so that the thickness of a line that is being drawn on display  24  can be adjusted accordingly or so that tablet computer  20  may take other suitable action. 
     If desired, stylus  10  may be provided with a clip to help attach stylus  10  to a user&#39;s shirt pocket or other object, may be provided with a magnet to help attach stylus  10  to a magnetic attachment point in tablet computer  20  or other structure, or may be provided with other structures that help a user attach stylus  10  to external objects. Components such as components  8  may be formed on stylus  10  (e.g., on shaft  16  or elsewhere). Components  8  may include buttons, touch sensors, and other components for gathering input, light-emitting diodes or other components for producing output, etc. Components  8  may, for example, include input-output components such as a data port connector that receives a cable or other wire-based connectors (e.g., a connector that supplies power signals for charging a battery in stylus  10  and/or that supplies digital data), conductive structures that receive wireless power for charging the battery in stylus  10  and/or that receive other wireless signals (e.g., near-field signals), or any other desired components. 
     Stylus  10  may include a metal tube or other conductive components in shaft  16 . The metal tube or other structures in stylus  10  may serve as an antenna ground for an antenna. The metal tube may also be used to ground components for sensors located at end  18  of stylus  10 . An antenna resonating element for the antenna may be formed from metal traces on a printed circuit or other dielectric support structure and/or from other conductive structures. As an example, an antenna resonating element may be at end  18  of stylus  10 . 
     A schematic diagram showing illustrative components that may be used in stylus  10  is shown in  FIG. 2 . As shown in  FIG. 2 , stylus  10  may include control circuitry such as storage and processing circuitry  30 . Storage and processing circuitry  30  may include storage such as 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  30  may be used to control the operation of stylus  10 . This processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processor integrated circuits, application specific integrated circuits, etc. 
     Storage and processing circuitry  30  may be used to run software on stylus  10 . The software may process input from buttons, sensors, and other input components. The software may also be used to provide output to a user (e.g., using light-emitting-diodes or other output components such as components  8  of  FIG. 1 ). To support interactions with external equipment such as tablet computer  20 , storage and processing circuitry  30  and other circuitry in stylus  10  may be used in implementing communications protocols. Communications protocols that may be implemented in stylus  10  include protocols for short-range wireless communications links such as the Bluetooth® protocol or other wireless personal area network (WPAN) protocols. If desired, other types of wireless communications links may be supported (e.g., wireless local area network (WLAN) communications links, satellite navigation links, etc.). The use of Bluetooth communications is merely illustrative. 
     Stylus  10  may include input-output circuitry  42 . Input-output circuitry  42  may include input-output devices  32 . Input-output devices  32  may be used to allow data to be supplied to stylus  10  and to allow data to be provided from stylus  10  to external devices such as tablet computer  20  ( FIG. 1 ). Input-output devices  32  may include user interface devices, data port devices, and other input-output components. For example, input-output devices  32  may include touch screens, displays without touch sensor capabilities, buttons, joysticks, scrolling wheels, touch pads, microphones, cameras, speakers, status indicators, light sources, audio jacks and other audio port components, digital data port devices, light sensors, accelerometers or other components that can detect motion and stylus orientation relative to the Earth, or other input-output components. 
     If desired, input-output devices  32  may include one or more sensors  36  such as capacitance sensors, proximity sensors (e.g., a capacitive proximity sensor and/or an infrared proximity sensor), magnetic sensors, and/or force sensors. Sensors  36  may be mounted at end  18  of stylus  10  ( FIG. 1 ) and may gather corresponding sensor data. Sensors  36  may, for example, sense the presence of display  24  and/or how stylus  10  is being used to interact with display  24  when end  18  is pointed towards or contacting the surface of display  24 . Sensors  36  may also gather sensor data indicative to how a user is holding or interacting with stylus  10  (e.g., touch sensor or proximity sensor data indicative of whether or not a user is touching end  18  of stylus  10 , force sensor data indicative of how hard a user is pressing against end  18  of stylus  10  with their hand, etc.). This sensor data may be conveyed to tablet computer  20  over wireless link  28  ( FIG. 1 ) for further processing if desired. 
     As shown in  FIG. 2 , input-output circuitry  42  may include wireless communications circuitry  34  for communicating wirelessly with external equipment. Wireless communications circuitry  34  may include radio-frequency transceiver circuitry formed from one or more integrated circuits, power amplifier circuitry, low-noise input amplifiers, passive radio-frequency components, one or more antennas  40 , radio-frequency transmission line paths, and other circuitry for handling radio-frequency wireless signals. 
     Wireless communications circuitry  34  may include radio-frequency transceiver circuitry  38  for handling wireless communications in the 2.4 GHz Bluetooth® communications band or other suitable communications bands (e.g., WPAN communications bands, WLAN communications bands, etc.). Bluetooth signals or other wireless signals may be transmitted and/or received by transceiver circuitry  38  using one or more antennas such as antenna  40 . Antennas in wireless communications circuitry  34  may be formed using any suitable antenna types. For example, antennas for stylus  10  may include antennas with resonating elements that are formed from loop antenna structures, patch antenna structures, inverted-F antenna structures, slot antenna structures, planar inverted-F antenna structures, helical antenna structures, ring antenna structures, monopole antenna structures, dipole antenna structures, hybrids of these designs, etc. If desired, one or more of the antennas in stylus  10  may be cavity-backed antennas. 
     Transmission line paths may be used to couple antenna  40  to transceiver circuitry  38 . Transmission line paths in stylus  10  may include coaxial cable paths, microstrip transmission lines, stripline transmission lines, edge-coupled microstrip transmission lines, edge-coupled stripline transmission lines, transmission lines formed from combinations of transmission lines of these types, etc. Filter circuitry, switching circuitry, impedance matching circuitry, and other circuitry may be interposed within the transmission line paths, if desired. 
     As shown in  FIG. 3 , transceiver circuitry  38  in wireless communications circuitry  34  may be coupled to antenna  40  using paths such as transmission line path  64 . Wireless communications circuitry  34  may be coupled to storage and processing circuitry  30 . Storage and processing circuitry  30  may be coupled to sensors  36  over paths such as sensor data path  86 . 
     Sensor data path  86  may include one or more conductive lines (e.g., conductive traces, wires, or other conductors) for coupling sensors  36  to storage and processing circuitry  30 . For example, sensor data path  86  may include one or more sensor data conductors that convey sensor signals gathered by sensors  36  to storage and processing circuitry  30  and one or more ground conductors that are coupled to ground in stylus  10 . Sensor signals conveyed over sensor data path  86  may include alternating current signals provided at frequencies that are much lower than the radio-frequencies handled by transceiver circuitry  38  (e.g., between 1 MHz and 5 MHz, below 1 MHz, or any other desired frequency below 600 MHz). Storage and processing circuitry  30  may also be coupled to other input-output devices  32  ( FIG. 2 ) over respective data paths. 
     To provide antenna  40  with the ability to cover communications frequencies of interest, antenna  40  may be provided with circuitry such as filter circuitry (e.g., one or more passive filters and/or one or more tunable filter circuits). Discrete components such as capacitors, inductors, and resistors may be incorporated into the filter circuitry. Capacitive structures, inductive structures, and resistive structures may also be formed from patterned metal structures (e.g., part of an antenna). 
     If desired, antenna  40  may be provided with adjustable circuits such as tunable components  102  to tune antenna  40  over communications bands of interest. Tunable components  102  may include tunable inductors, tunable capacitors, or other tunable components. Tunable components such as these may be based on switches and networks of fixed components, distributed metal structures that produce associated distributed capacitances and inductances, variable solid state devices for producing variable capacitance and inductance values, tunable filters, or other suitable tunable structures. During operation of stylus  10 , storage and processing circuitry  30  may issue control signals on one or more paths such as control path  88  that adjust inductance values, capacitance values, or other parameters associated with tunable components  102 , thereby tuning antenna  40  to cover desired communications bands. Configurations in which antenna  40  is free of tunable components may also be used. 
     Transceiver circuitry  38  may be coupled to antenna  40  over a signal path such as transmission line path  64 . Transmission line path  64  may include one or more radio-frequency transmission lines. As an example, transmission line path  64  of  FIG. 3  may be a radio-frequency transmission line having a positive signal conductor such as positive signal conductor (line)  94  and a ground signal conductor such as ground conductor (line)  96 . Conductors  94  and  96  may form parts of a coaxial cable or a microstrip transmission line (as examples). A matching network formed from components such as inductors, resistors, and capacitors may be used in matching the impedance of antenna  40  to the impedance of transmission line path  64 . Matching network components may be provided as discrete components (e.g., surface mount technology components) or may be formed from housing structures, printed circuit board structures, traces on plastic supports, etc. Components such as these may also be used in forming filter circuitry in antenna  40 . 
     Transmission line path  64  may be coupled to antenna feed structures associated with antenna  40 . As an example, antenna  40  may form an inverted-F antenna, a slot antenna, a hybrid inverted-F slot antenna or other antenna having an antenna feed  84  with a positive antenna feed terminal such as terminal  98  and a ground antenna feed terminal such as terminal  100 . Positive signal conductor  94  may be coupled to positive antenna feed terminal  98  and ground conductor  96  may be coupled to ground antenna feed terminal  100 . Other types of antenna feed arrangements may be used if desired. The illustrative feeding configuration of  FIG. 3  is merely illustrative. 
     Storage and processing circuitry  30  may use the sensor signals gathered by sensors  36  and received over sensor data path  86  to perform any desired operations on device  10 . For example, storage and processing circuitry  30  may control other input-output devices  32  ( FIG. 2 ) based on the sensor signals. In another suitable arrangement, storage and processing circuitry  30  may adjust antenna  40  (e.g., using control signals provided to tunable components  102  over control path  88 ) based on the sensor signals. Control circuitry  30  may generate sensor data based on the sensor signals received over sensor data path  86 . Control circuitry  30  may transmit the sensor data to transceiver circuitry  38 . Transceiver circuitry  38  may generate radio-frequency sensor data based on the sensor data received from control circuitry  30 . Transceiver circuitry  38  may use antenna  40  to transmit the radio-frequency sensor data to tablet computer  20  over wireless link  28  ( FIG. 1 ). 
     Transmission line paths in device  10  such as transmission line path  64  may be integrated into rigid and/or flexible printed circuit boards. In one suitable arrangement, transmission line paths such as transmission line path  64  may also include transmission line conductors (e.g., positive signal conductors  94  and ground conductors  96 ) integrated within multilayer laminated structures (e.g., layers of a conductive material such as copper and a dielectric material such as a resin that are laminated together without intervening adhesive). The multilayer laminated structures may, if desired, be folded or bent in multiple dimensions (e.g., two or three dimensions) and may maintain a bent or folded shape after bending (e.g., the multilayer laminated structures may be folded into a particular three-dimensional shape to route around other device components and may be rigid enough to hold its shape after folding without being held in place by stiffeners or other structures). All of the multiple layers of the laminated structures may be batch laminated together (e.g., in a single pressing process) without adhesive (e.g., as opposed to performing multiple pressing processes to laminate multiple layers together with adhesive). 
       FIG. 4  is a diagram of illustrative inverted-F antenna structures that may be used in implementing antenna  40  for stylus  10 . Inverted-F antenna  40  of  FIG. 4  has antenna resonating element  106  and antenna ground  104  (sometimes referred to herein as ground structures  104 , ground plane  104 , or ground  104 ). Antenna resonating element  106  (sometimes referred to herein as antenna radiating element  106 ) may have a main resonating element arm such as arm  108  (sometimes referred to herein as antenna resonating element arm  108 , antenna radiating element arm  108 , radiating arm  108 , or arm  108 ). The length of antenna resonating element arm  108  may be selected so that antenna  40  resonates at desired operating frequencies. For example, the length of antenna resonating element arm  108  may be a quarter of a wavelength at a desired operating frequency for antenna  40  (e.g., 2.4 GHz). Antenna  40  may also exhibit resonances at harmonic frequencies. 
     Antenna resonating element arm  108  may be coupled to ground  104  by return path  110 . Antenna feed  84  may include positive antenna feed terminal  98  and ground antenna feed terminal  100  and may run parallel to return path  110  between antenna resonating element arm  108  and ground  104 . If desired, inverted-F antennas such as illustrative antenna  40  of  FIG. 4  may have more than one resonating arm branch (e.g., to create multiple frequency resonances to support operations in multiple communications bands) or may have other antenna structures (e.g., parasitic antenna resonating elements, tunable components such as components  102  of  FIG. 3  to support antenna tuning, etc.). Antenna resonating element arm  108  may follow a meandering path or may have other shapes if desired (e.g., shapes having curved and/or straight segments). 
     In mounting antenna  40  in stylus  10 , the structures of antenna  40  may be curved. For example, ground  104  and/or antenna resonating element  106  may be formed from metal that wraps around longitudinal axis  12  of stylus  10  ( FIG. 1 ). Ground  104  and/or antenna resonating element  106  may be curved in three-dimensions (e.g., ground  104  and/or antenna resonating element  106  may be formed from conductive traces having a concave shape or dome-shape that extends over end  18  of stylus  10  as shown in  FIG. 1 ). The example of  FIG. 4  is merely illustrative and, if desired, antenna  40  may be implemented using other types of antenna structures. 
     Antenna  40  may be formed from conductive structures such as metal structures. The metal structures of antenna  40  may be metal coating layers, portions of a device housing or other structural metal member, portions of a metal tube, metal foil, wires, or other metal structures. 
     In the illustrative configuration of  FIG. 5 , antenna  40  includes three-dimensional metal antenna resonating element arm  108  on three-dimensional (non-planar) dielectric support  130 . Dielectric support  130  may be, for example, a support formed from a dielectric such as plastic (e.g., molded plastic). The plastic material that forms support  130  may be provided with metal particles or other filler material that sensitizes support  130  to exposure from laser light. Following exposure to laser light, portions of support  130  that have been exposed to laser light will promote coating with electroplated metal, whereas portions of support  130  that have not been exposed to laser light will not promote electroplating metal growth. With this approach, which may sometimes be referred to as laser direct structuring (LDS), metal structures such as metal antenna resonating element arm  108  of  FIG. 5  may be deposited using electroplating. The metal antenna structures that are grown in this way can be three-dimensional (i.e., a curved surface such as the curved surface of illustrative support structure  130  of  FIG. 5  can be coated with metal). Use of a three-dimensional antenna structure may help create a desired antenna radiation pattern for antenna  40  while accommodating antenna  40  within a housing of a desired shape. 
     In the example of  FIG. 6 , metal traces for antenna resonating element arm  108  have been deposited and patterned on a flexible substrate such as flexible substrate  132 . The metal for forming antenna structures such as antenna resonating element arm  108  can be deposited as a blanket metal coating and subsequently patterned using photolithography and metal etching (as an example). Flexible substrate  132  may be a flexible printed circuit formed from a polyimide substrate or a flexible layer of other polymer material. When installed in stylus  10 , flexible substrate  132  may wrapped around the elongated body of stylus  10  (e.g., around longitudinal axis  12  of  FIG. 1 ). 
       FIG. 7  is an exploded perspective view of an illustrative antenna resonating element arm  108  for antenna  40  that is formed from a metal member (e.g., stamped metal foil, etc.) that is attached to dielectric support member  134  using adhesive  136 . Support member  134  may be formed from plastic or other dielectric materials and may form a portion of the elongated body of stylus  10 . 
       FIG. 8  is a diagram showing how metal antenna resonating element arm  108  and other antenna structures may be formed by printing conductive ink  144  onto the surface of dielectric support  138 . Dielectric support  138  may be a planar substrate such as a printed circuit substrate or may be a molded plastic support or other structure that has a three-dimensional shape. Ink-jet dispenser  140  may be controlled using computer-controlled positioner  142 . When moved in direction  146 , dispenser  140  may deposit metal ink or other conductive ink  144  onto support structure  138 , thereby forming a desired shape for antenna resonating element arm  108  of antenna  40 . Conductive ink (e.g., binder material that contains metal particles or other conductive particles) may be applied to a support structure using ink-jet printing, screen printing, pad printing, spraying, dipping, dripping, painting, or other suitable deposition techniques. 
     The antenna metal structure fabrication techniques described in connection with  FIGS. 5-8  are merely illustrative. Antenna structures may be formed from portions of metal housings (e.g., metal tubes that form structures for the elongated body of stylus  10 ), internal metal members, metal traces on flexible printed circuits, three-dimensional metal traces (e.g., laser patterned traces) on molded plastic substrates and other three-dimensional dielectric substrates, metal wires, metal foil (e.g., metal foil that has been patterned into the shape of an antenna structure and that is attached to a support structure using adhesive, screws, or other attachment mechanisms). 
     The housing of stylus  10  may be formed from metal, plastic, carbon-fiber composites and other fiber composites, glass, ceramic, other materials, and combinations of these materials. A cross-sectional side view of a shaft  16  of the elongated body of stylus  10  ( FIG. 1 ) is shown in  FIG. 9 . As shown in  FIG. 9 , electrical components  150  may be mounted within interior cavity  152  of the elongated body of stylus  10 . Components  150  may include integrated circuits, sensors, battery structures, connectors, switches, and other circuitry (e.g., storage and processing circuitry  30  and/or input-output circuitry  42  of  FIG. 2 ). Components  150  may be mounted on one or more substrates such as substrate  154 . Substrate  154  may be a dielectric support structure such as a printed circuit (e.g., a rigid printed circuit formed from a rigid printed circuit board material such as fiberglass-filled epoxy or a flexible printed circuit formed from a flexible sheet of polyimide or other flexible polymer layer). 
     Interior cavity  152  may be surrounded by one or more layers of material such as layers  156 ,  158 , and  160 . These layers of material may form concentric cylindrical tubes and may be formed from metal, plastic, glass, ceramic, other materials, and/or two or more of these materials. As an example, outer layer  156  may form a plastic tube that serves as a cosmetic exterior for stylus  10 , intermediate layer  158  may form a metal tube that provides stylus  10  with structural support, and inner layer  160  may form a plastic tube that serves as a support structure. In general, tube  156  may be formed from metal, plastic, carbon fiber, ceramic, or other materials, tube  158  may be formed from metal, plastic, carbon fiber, ceramic, or other materials, and tube  160  may be formed from metal, plastic, carbon fiber, ceramic, or other materials. With another illustrative arrangement, inner tube  160  may be omitted, tube  156  may be formed from metal, plastic, or other materials and tube  158  may be formed from metal, plastic, or other materials. Configurations in which shaft  16  includes a single tube or includes solid portions without significant interior cavity portions may also be used. 
     As shown in the cross-sectional side view of stylus  10  of  FIG. 10 , antenna  40  may be formed at end  18  of stylus  10 . With this type of arrangement, the risk of inadvertently blocking antenna  40  with the hand of a user may be minimized. One or more sensors  36  may also be formed at end  18  of stylus  10 . Antenna  40  and sensor  36  may both be formed using metal structures at end  18  of stylus  10  (e.g., metal structures such as conductive traces on an underlying substrate or other metal structures as described above in connection with  FIGS. 5-8 ). The metal structures used to form antenna  40  may include, for example, conductive traces that form antenna resonating element  106  ( FIG. 4 ). The metal structures used to form sensor  36  may include, for example, conductive electrodes (e.g., capacitive and/or resistive electrodes), conductive traces, other conductive structures, and/or portions of sensor data path  86  ( FIG. 3 ). 
     If care is not taken, the metal structures used to form sensor  36  may block radio-frequency signals that are transmitted or received by antenna  40 , harmonics of the sensor signals generated by sensor  36  may interfere with the radio-frequency signals handled by antenna  40 , and/or the radio-frequency signals handled by antenna  40  may interfere with sensor signals generated by sensor  36 . In order to generate reliable sensor signals, the metal structures used to form sensor  36  may be coupled to ground within stylus  10 . For example, the metal structures may be shorted (grounded) to tube  158  in shaft  16  in scenarios where tube  158  is formed from metal ( FIG. 9 ). Tube  158  may sometimes be referred to herein as metal tube  158 . If care is not taken, grounding the metal structures of sensor  36  may limit the antenna efficiency of antenna  40  in the frequency band of operation for antenna  40 . For example, the presence of grounded metal structures in sensor  36  may reduce the antenna efficiency of antenna  40  by 6 dB or greater at Bluetooth frequencies (e.g., 2.4 GHz) relative to scenarios where sensor  36  is omitted from end  18  of stylus  10 . 
       FIG. 11  is a perspective view of end  18  of stylus  10  showing one example of how sensor  36  and antenna  40  may be implemented to mitigate these issues. Antenna  40  and sensor  36  may both be formed from conductive structures such as metal traces (or other metal structures as described above in connection with  FIGS. 5-8 ) formed on a three-dimensional support structure such as support structure  170  at end  18  of stylus  10 . Support structure  170  may be formed from molded plastic, ceramic, polymers, glass, or any other desired dielectric materials and may sometimes be referred to herein as dielectric substrate  170  or substrate  170 . Substrate  170  may be hollow or may have hollow portions (interior cavities). Substrate  170  may have a cylindrical shape, a dome shape (e.g., a spherical or elliptical dome shape or other curved shape having a radius of curvature pointed towards tip  14  of  FIG. 1 ), a prismatic shape, or combinations of these and/or other shapes, as examples. The conductive structures (e.g., metal traces) used to form antenna  40  and sensor  36  may conform to the shape of the underlying substrate  170  (e.g., the conductive structures used to form antenna  40  and sensor  36  may be cylindrically shaped, dome-shaped, etc.). 
     Antenna  40  may be an inverted-F antenna and the metal traces may include a portion that forms antenna resonating element  106  on substrate  170  (e.g., antenna resonating arm  108  and return path  110  of  FIG. 4 ). Antenna  40  may include an antenna ground formed from metal tube  158  within shaft  16  of stylus  10  (e.g., ground  104  of  FIG. 4 ). Antenna resonating element  106  may be shorted (grounded) to metal tube  158  at point  182 . Antenna resonating element  106  may be coupled to metal tube  158  at point  182  using solder, welds, conductive adhesive, a conductive screw, conductive pin, conductive spring, and/or any other desired conductive interconnect structures. In another suitable arrangement, antenna resonating element  106  may be formed from an integral portion of metal tube  158  that extends over substrate  170 . 
     Antenna resonating element arm  108  may extend from return path  110  and around longitudinal axis  12  (e.g., around the circumference of substrate  170 ). For example, antenna resonating element arm  108  may extend at least 120 degrees around longitudinal axis  12 , at least 150 degrees around longitudinal axis  12 , at least 180 degrees around longitudinal axis  12 , at least 210 degrees around longitudinal axis  12 , at least 270 degrees around longitudinal axis  12 , 240 degrees around longitudinal axis  12 , between 180 and 250 degrees around longitudinal axis  12 , or any other desired angle between approximately 120 degrees and 270 degrees around longitudinal axis  12 . 
     Transmission line path  64  ( FIG. 3 ) may be implemented using a coaxial cable or other transmission line structure having a ground conductor coupled to ground antenna feed terminal  100  on metal tube  158  and a positive signal conductor  94  coupled to positive antenna feed terminal  98  on antenna resonating element arm  108 . In another suitable arrangement, ground antenna feed terminal  100  may be coupled to additional metal traces on substrate  170 . 
     The ground conductor and positive signal conductor  94  may extend parallel to longitudinal axis  12  to internal components such as electrical components  150  ( FIG. 9 ) mounted within shaft  16  (e.g., internal components such as transceiver circuitry  38  of  FIG. 2 ). Positive signal conductor  94  may include a conductive wire, conductive trace, or other conductive line that extends from the interior of metal tube  158  (e.g., interior cavity  152  of  FIG. 9 ) to positive antenna feed terminal  98  over an exterior surface of substrate  170 . In another suitable arrangement, positive signal conductor  94  may extend through a hollow interior of substrate  170  to positive antenna feed terminal  98  (e.g., a via, conductive pin, conductive spring, or other conductive interconnect may be used to couple conductive lines located within the hollow interior of substrate  170  to the location of positive antenna feed terminal  98  at the exterior of substrate  170 ). If desired, positive signal conductor  94  may include both portions that extend within the interior of substrate  170  and portions that extend external to substrate  170 . 
     Sensor  36  may include conductive structures  172  on substrate  170 . Conductive structures  172  may include one or more conductive electrodes for sensor  36 , for example. Conductive structures  172  may be formed from metal traces on substrate  170  or from other metal structures such as the metal structures described above in connection with  FIGS. 5-8 . Conductive structures  172  may sometimes be referred to herein as sensor traces  172 , sensor electrodes  172 , conductive electrode(s)  172 , or sensor conductor  172 . Antenna resonating element arm  108  may be interposed between sensor traces  172  and shaft  16  (metal tube  158 ). This may, for example, allow sensor  36  to serve as a digital eraser for stylus  10  when interacting with tablet computer  20  ( FIG. 1 ) and/or to gather sensor signals associated with objects that come into proximity or contact with end  18  of stylus  10 . Sensor signals gathered by sensor  36  may include capacitance information, resistance information, inductance information, thermal information, and/or any other desired sensor information gathered (sensed) by sensor traces  172  from the surroundings of stylus  10 . 
     Sensor traces  172  may be coupled to storage and processing circuitry  30  over a sensor data path such as sensor data path  86  ( FIG. 3 ). Sensor data path  86  may include one or more conductive lines such as one or more signal lines and one or more ground lines. Sensor  36  may include a conductive path such as sensor leg  174  that extends from sensor traces  172  towards metal tube  158 . Sensor leg  174  and sensor traces  172  may be formed from the same piece of conductive material if desired (e.g., sensor traces  172  and sensor leg  174  may both be formed from metal traces patterned or deposited onto substrate  170 ). 
     Sensor leg  174  (sometimes referred to herein as conductive leg  174  or leg portion  174  of sensor traces  172 ) may be used to implement part of one or more conductive lines for sensor data path  86  of  FIG. 3 . For example, sensor leg  174  may be used to form one or more signal lines and/or one or more ground lines for sensor data path  86 . Sensor leg  174  may include a terminal such as sensor terminal  176  located at the end of sensor leg  174  opposite to sensor traces  172 . 
     Sensor terminal  176  may be coupled to storage and processing circuitry  30  within shaft  16 . For example, portions of the signal lines and/or ground lines in sensor data path  86  may couple sensor terminal  176  to storage and processing circuitry  30 . These portions of sensor data path  86  may extend from sensor terminal  176  into the interior of metal tube  158  at the exterior surface of substrate  170  and/or may extend through a hollow cavity within substrate  170  (e.g., these portions of sensor data path  86  may be coupled from the interior of substrate  170  to sensor terminal  176  using vias, pins, springs, or other conductive interconnects). In this case, antenna resonating element arm  108  can occupy larger amount of space than shown in  FIG. 11  and may extend more than 360 degrees around substrate  170  if desired. 
     Sensor data path  86  ( FIG. 3 ) may be grounded within stylus  10  to ensure that sensor  36  gathers accurate and reliable sensor signals during operation. For example, the ground lines in sensor data path  86  may be coupled to grounded structures within stylus  10  such as metal tube  158 . If desired, one or more signal lines in sensor data path  86  may also be coupled to grounded structures within stylus  10  such as metal tube  158 . 
     As shown in  FIG. 11 , in order to ensure that sensor data path  86  is grounded, sensor terminal  176  on sensor leg  174  may be coupled to ground terminal  178  on metal tube  158  (e.g., using solder, welds, conductive adhesive, conductive screws, conductive pins, conductive springs, etc.). Sensor terminal  176  may be coupled to storage and processing circuitry  30  ( FIG. 3 ) within shaft  16  in addition to being coupled to ground terminal  178  on metal tube  158 , if desired. In this way, sensor leg  174  may form part of a ground line for sensor data path  86  or may form part of a grounded signal line for sensor data path  86 . 
     In practice, grounding sensor traces  172  may undesirably load of antenna  40  on substrate  170 . If care is not taken, this loading may deteriorate the overall antenna efficiency of antenna  40  within the frequency band of operation of antenna  40 . A filtering component such as filter  180  may be coupled between sensor terminal  176  and ground terminal  178  to mitigate this deterioration in antenna performance. 
     Filter  180  may include, for example, a choke inductor having a first terminal coupled to sensor terminal  176  and a second terminal coupled to ground terminal  178 . The choke inductor may have an inductance that is selected so that filter  180  forms an open circuit at the radio-frequencies handled by antenna  40  (e.g., frequencies greater than 600 MHz) and so that filter  180  forms a short circuit path between sensor terminal  176  and ground terminal  178  at the frequencies of the sensor signals generated by sensor  36  (e.g., frequencies below 1 MHz, between 1 and 5 MHz, below 600 MHz, etc.). In this way, filter  180  may block radio-frequency signals (e.g., antenna currents at radio-frequencies) from being conveyed between sensor leg  174  and metal tube  158 , even though sensor leg  174  is grounded to metal tube  158  at lower frequencies. Blocking the radio-frequency signals from being conveyed between sensor  36  and metal tube  158  may serve to isolate sensor  36  from antenna  40  (e.g., so that sensor  36  acts as a floating conductor above antenna  40  at radio-frequencies), thereby minimizing the loading of antenna  40  by sensor  36  and maximizing the overall antenna efficiency for antenna  40 . 
     This example is merely illustrative and, in general, filter  180  may include a low pass filter, a high pass filter, a band pass filter, a notch filter, capacitors, resistors, or any other desired combination of any number of capacitors, resistors and/or inductors coupled in any desired manner between sensor terminal  176  and ground terminal  178 . In another suitable arrangement, filter  180  may include a third terminal that is coupled to storage and processing circuitry  30  (e.g., a third terminal that is coupled to a portion of sensor data path  86  extending to storage and processing circuitry  30  of  FIG. 3 ). In scenarios where filter  180  includes a third terminal coupled to storage and processing circuitry  30 , sensor terminal  176  need not be separately coupled to storage and processing circuitry  30 , if desired. 
     The example of  FIG. 11  is merely illustrative. In general, sensor traces  172 , sensor leg  174 , and antenna resonating element  106  may have any desired shapes and sizes (e.g., shapes having any desired number of straight and/or curved edges). Additional signal lines and/or ground lines from sensor data path  86  ( FIG. 3 ) may be coupled to any desired locations on sensor traces  172  and sensor leg  174 . 
     The presence of sensor leg  174  may impose a limit on how far antenna resonating element arm  108  can extend around longitudinal axis  12 . If desired, additional sensor legs may be coupled between sensor traces  172  and metal tube  158 . Forming additional sensor legs in sensor  36  may further limit how far antenna resonating element arm  108  can extend around longitudinal axis  12 . However, additional sensor legs may enhance the structural and mechanical integrity of sensor  36  relative to scenarios where only a single sensor leg is used, for example. 
       FIG. 12  is a perspective view of end  18  of stylus  10  showing how sensor  36  may include two sensor legs coupled between sensor traces  172  and metal tube  158 . As shown in  FIG. 12 , sensor  36  may include an additional sensor leg  194  extending from sensor traces  172  towards metal tube  158 . Sensor  36  may include a sensor terminal  196  at the end of sensor leg  194 . Sensor terminal  196  may be coupled to ground terminal  198  on metal tube  158  (e.g., using solder, welds, conductive adhesive, conductive screws, conductive pins, conductive springs, etc.). Sensor terminal  196  may be coupled to storage and processing circuitry  30  ( FIG. 3 ) within shaft  16  in addition to being coupled to ground terminal  178  on metal tube  158 , for example. In this way, sensor leg  194  may form part of a ground line for sensor data path  86  or may form part of a grounded signal line for sensor data path  86 . 
     In order to mitigate the impact of sensor  36  on antenna  40 , a filtering circuit such as filter  200  may be coupled between sensor terminal  196  and ground terminal  198 . Filter  200  may include, for example, a choke inductor having a first terminal coupled to sensor terminal  196  and a second terminal coupled to ground terminal  198 . The choke inductor may have an inductance that is selected so that filter  200  forms an open circuit at the radio-frequencies and so that filter  200  forms a short circuit path between sensor terminal  196  and ground terminal  198  at the frequencies of the sensor signals generated by sensor  36 . In this way, filter  200  may block radio-frequency signals (e.g., antenna currents at radio-frequencies) from being conveyed between sensor leg  194  and metal tube  158 , even though sensor leg  194  is grounded to metal tube  158  at lower frequencies. Blocking the radio-frequency signals from being conveyed between sensor  36  and metal tube  158  may serve to isolate sensor  36  from antenna  40 , thereby minimizing the loading of antenna  40  by sensor  36  and maximizing the overall antenna efficiency for antenna  40 . 
     This example is merely illustrative and, in general, filter  200  may include a low pass filter, a high pass filter, a band pass filter, a notch filter, capacitors, resistors, or any other desired combination of any number of capacitors, resistors and/or inductors coupled in any desired manner between sensor terminal  196  and ground terminal  198 . In another suitable arrangement, filter  200  may include a third terminal that is coupled to storage and processing circuitry  30  (e.g., a third terminal that is coupled to a portion of sensor data path  86  extending to storage and processing circuitry  30  of  FIG. 3 ). In scenarios where filter  200  includes a third terminal coupled to storage and processing circuitry  30 , sensor terminal  196  need not be separately coupled to storage and processing circuitry  30 , if desired. 
     Forming sensor  36  with additional sensor leg  194  may enhance the structural and mechanical integrity of sensor  36  and end  18  of stylus  10  relative to scenarios where only a single sensor leg is used, for example. At the same time, the presence of additional sensor leg  194  of  FIG. 12  may further limit the amount of surface area on substrate  170  that is available for antenna  40 . If desired, sensor leg  174  may be rotationally separated from sensor leg  194  around longitudinal axis  12  by between 180 degrees and 270 degrees so that between 180 and 270 degrees of rotational area around longitudinal axis  12  is available for forming antenna  40  on substrate  170 . 
     If desired, antenna resonating element arm  108  may include one or more bends so that antenna  40  may fit within the limited space between sensor legs  174  and  194 . As shown in  FIG. 12 , antenna resonating element arm  108  may follow a path that extends from return path  110  to end (tip)  192  and that includes first and second bends or folds (e.g., perpendicular bends or bends of other angles). This may allow antenna resonating element arm  108  to have the same length (e.g., approximately one-quarter of the wavelength of operation of antenna  40 ) as in scenarios where only one sensor leg  174  is formed while conforming to the limited amount of space available between sensor legs  174  and  194  of  FIG. 12 , for example. 
     The example of  FIG. 12  is merely illustrative. In general, antenna resonating element arm  108  may have any desired number of bends in any desired directions. A third sensor leg and/or additional sensor legs may be coupled to sensor traces  172  at the side of substrate  170  opposite to antenna  40  if desired. 
     If desired, some or all of sensor  36  and antenna  40  may be formed from the same conductive structure (e.g., metal traces) on substrate  170  (e.g., sensor  36  and antenna  40  may be formed from shared conductive structures or metal traces on substrate  170 ).  FIG. 13  is a perspective view of end  18  of stylus  10  showing how sensor  36  and antenna  40  may be formed from shared conductive structures on substrate  170 . 
     As shown in  FIG. 13 , antenna resonating element arm  108  of antenna  40  may be coupled to sensor traces  172  over conductor  212  on substrate  170  (e.g., a conductive trace on substrate  170  that extends from sensor traces  172  to antenna resonating element arm  108 ). Conductive trace  212  may serve to short antenna resonating element arm  108  (e.g., end  192  of antenna resonating element arm  108 ) to sensor traces  172 . When configured in this way, sensor  36  may also include some or all of antenna resonating element arm  108  and may use antenna resonating element arm  108  to gather sensor signals for storage and processing circuitry  30  ( FIG. 2 ). At the same time, antenna  40  may also include some or all of sensor traces  172  and sensor leg  174  to convey radio-frequency signals. 
     For example, antenna currents at radio-frequencies may be conveyed to and from antenna  40  over antenna feed terminals  98  and  100 . The antenna currents may flow over antenna resonating element arm  108 , return path  110 , metal tube  158 , conductive trace  212 , some or all of sensor traces  172 , and sensor leg  174 . In scenarios where filter  180  is a choke inductor coupled to ground terminal  178 , sensor terminal  176  may form an open circuit to the antenna currents. This may extend the effective length of the antenna resonating element arm for antenna  40  to also include conductive structure  212 , sensor traces  172 , and sensor leg  174 , as shown by path  215 . This may allow antenna resonating element arm  108  to be reduced in size (e.g., to conform to a smaller amount of available area around longitudinal axis  12  on substrate  170 ) while still maintaining sufficient radiating length for antenna  40  (e.g., path  215  may be approximately one-quarter of the wavelength of operation of antenna  40 ). 
     In another suitable arrangement, filter  180  may be omitted and sensor terminal  176  may be shorted directly to ground terminal  178 . When configured in this way, sensor leg  174  may serve as an additional return path between the antenna resonating element of antenna  40  and ground (metal tube  158 ). In yet another suitable arrangement, capacitive, resistive, and/or inductive components may be arranged within filter  180  to tune the frequency response of antenna  40 . 
     As shown in  FIG. 13 , transmission line path  64  may be coupled to antenna feed terminals  98  and  100  (e.g., positive signal conductor  94  of transmission line path  64  may be coupled to positive antenna feed terminal  98  whereas ground conductor  96  of transmission line path  64  is coupled to ground antenna feed terminal  100 ). If desired, additional filtering circuitry such as filter  214  may be interposed on transmission line path  64 . Filter  214  may, for example, include one or more capacitors interposed on conductors  96  and/or  94 . The capacitors may have a capacitance selected to form a short circuit at radio-frequencies and to form an open circuit at lower frequencies such as the frequencies associated with the sensor signals gathered by sensor  36 . This may serve to isolate transceiver circuitry  38  ( FIG. 3 ) from the sensor signals if desired. In another suitable arrangement, additional filtering components may be formed within transceiver circuitry  38  and/or control circuit  30  ( FIG. 3 ) to reduce signal interference between sensor  36  and antenna  40  if desired. 
     The example of  FIG. 13  is merely illustrative. Additional sensor legs such as sensor leg  194  of  FIG. 13  may be formed on substrate  170  (e.g., at a side of antenna  40  opposite to sensor leg  174 ). Conductive structure  212  may be coupled to antenna resonating element arm  108  at any desired location. Sharing conductive structures between antenna  40  and sensor  36  may optimize space consumption within end  18  of stylus  10  without significantly sacrificing wireless performance for antenna  40  or the performance of sensor  36 , for example. 
     In another suitable arrangement, the conductive structures in sensor  36  may overlap with antenna resonating element arm  108  on substrate  170  (e.g., sensor  36  may be formed from conductive structures that overlap antenna resonating element arm  108  without contacting antenna resonating element arm  108 ).  FIG. 14  is a perspective view of end  18  of stylus  10  showing how sensor  36  and antenna  40  may be formed from overlapping conductive structures on substrate  170 . 
     As shown in  FIG. 14 , sensor traces  172  and sensor leg  174  may be formed on an additional dielectric substrate such as dielectric substrate  232 . Dielectric substrate  232  may be a flexible printed circuit or other substrate that is bent around and conforms to the shape of substrate  170 . Dielectric substrate circuit  232  may have an end that is mounted on or over antenna resonating element arm  108 . 
     Sensor  36  may include a conductive segment  234  (e.g., a portion of sensor traces  172  or an additional sensor leg such as sensor leg  194  of  FIG. 12 ) at the end of dielectric substrate  232  that overlaps antenna resonating element arm  108 . Dielectric substrate  232  may isolate or separate conductive segment  234  from antenna resonating element arm  108  if desired. In this way, antenna  40  and sensor  36  may be formed from overlapping conductive structures. This may, for example, serve to optimize space consumption within end  18  of stylus  10  (e.g., antenna resonating element arm  108  may have sufficient length and sensor  36  may have a sufficient sensor signal collection area despite both antenna  40  and sensor  36  being confined to end  18  of stylus  10 ). 
     In another suitable arrangement, conductive segment  234  may be capacitively coupled to antenna resonating element arm  108  through dielectric substrate  232 . In this scenario, a short circuit may be formed between antenna resonating element arm  108  and conductive segment  234  at radio-frequencies, thereby extending the effective radiating length of antenna  40  to also include conductive segment  234 , sensor traces  172 , and/or sensor leg  174 . At the same time, dielectric substrate  232  may form an open circuit between conductive segment  234  and antenna resonating element arm  108  at lower frequencies such as frequencies associated with the sensor signals gathered by sensor  36  (e.g., dielectric substrate  232  may isolate antenna resonating element arm  108  from sensor signals generated by sensor  36  while also allowing portions of sensor  36  to form a part of antenna  40 ). The example of  FIG. 14  is merely illustrative. Additional sensor legs may be coupled to sensor traces  172  if desired. Antenna resonating element arm  108  may have other shapes. 
     If desired, sensor traces  172  of  FIGS. 11-14  may include multiple conductive traces such as driver traces, receiver traces, and ground traces.  FIG. 15  is a top-down diagram showing how sensor traces  172  may include driver traces, receiver traces, and ground traces. 
     As shown in  FIG. 15 , sensor traces  172  of sensor  36  may include driver traces  172 D, receiver traces  172 R, and ground traces  172 G. Driver traces  172 D may be coupled to signal lines  240  of sensor data path  86 . Receiver traces  172 R may be coupled to signal lines  242  of sensor data path  86 . Receiver traces  172 R and driver traces  172 D may be arranged in a grid or array pattern, as one example. In another suitable arrangement, traces  172 R and  172 D may be replaced by a grid or array of conductive patches. Receiver traces  172 R may sometimes be referred to herein as receiver electrodes  172 R. Driver traces  172 D may sometimes be referred to herein as driver electrodes  172 D. 
     Ground traces  172 G (sometimes referred to herein as ground electrode  172 G) may be held at a ground potential and may include a ring or loop-shaped electrode such that surrounds traces  172 R and  172 D, for example. Ground electrode  172  may be coupled to ground at terminal  246  and/or terminal  244 . If desired, terminal  246  and/or terminal  244  may be coupled to metal tube  158  through corresponding sensor legs and filters (e.g., sensor legs such as sensor legs  174  and  194  and filters such as filters  180  and  200  of  FIGS. 11-14 ). If desired, one or more of signal lines  240  and  242  may be coupled to one or more sensor legs (e.g., in scenarios where signal lines  240  and  242  are grounded along their length). In another suitable arrangement, terminal  246  may be coupled to conductive structure  212  and antenna resonating element arm  108  ( FIG. 13 ). In these scenarios, terminal  244  may be coupled to metal tube  158  over a sensor feed leg such as sensor legs  174  and  194  of  FIGS. 11-14 . In yet another suitable arrangement, terminal  246  may form a ground antenna feed terminal such as ground antenna feed terminal  100  and terminal  244  may form a positive antenna feed terminal such as positive antenna feed terminal  98  of  FIG. 3  (e.g., ground traces  172 G need not be grounded and may, if desired, form a loop antenna resonating element for antenna  40  in scenarios where antenna  40  is a loop antenna). 
     Storage and processing circuitry  30  ( FIG. 3 ) may drive signals onto driver traces  172 D by providing drive signals (e.g., alternating current signals at relatively low frequencies such as 1 to 5 MHz) over signal lines  240 . Receiver traces  172 R may generate sensor signals corresponding to the drive signals used to driver traces  172 D. For example, during operation, a user may swipe a finger or display  24  of tablet computer  20  ( FIG. 1 ) across sensor  36 . During this action, storage and processing circuitry  30  may drive the drive signals into driver traces  172 D. This drive signals may be coupled into the user&#39;s finger (or display  24  of tablet computer  20 ) from driver traces  172 D when the user&#39;s finger (or display  24 ) is placed over driver traces  172 D (i.e., due to the contact of the user&#39;s finger or display  24  with at least some of driver traces  172 D or due to the close proximity of the finger or display  24  to driver traces  172 D in scenarios in which sensor traces  172  are separated from the exterior of stylus  10  by an air gap or a layer of plastic, glass, or other dielectric). The magnitude of the drive signals that are coupled to each of receiver traces  172 R from the user&#39;s finger (or display  24 ) may be measured by monitoring the signals on signal lines  242 . These signals may form sensor signals that are conveyed to storage and processing circuitry  30  over sensor data path  86 , for example. The sensor signals may be indicative of a capacitance, resistance, and/or inductance between sensor  36  and an external object, indicative of an external force applied to sensor  36 , etc. Storage and processing circuitry  30  may process the sensor signals to sense touch, proximity, force, etc. 
     The example of  FIG. 15  is merely illustrative. Ground traces  172 G, driver traces  172 D, and receiver traces  172 R may have any other desired shape, arrangement, and/or orientation. The conductive traces in sensor  36  may be provided with other arrangements if desired. Sensor  36  need not include a grid of driver and receiver traces surrounded by a ground trace. One or more of traces  172 R,  172 D, and  172 G may be omitted if desired. Sensor  36  may include other components for forming other types of sensors if desired (e.g., temperature sensors, light sensors, orientation sensors, etc.). The structures shown in  FIGS. 11-15  may be arranged in any desired combination. If desired, dielectric material such as a dielectric cap, an extension of outer tube  156  of  FIG. 9 , a cosmetic layer, an ink layer, and/or other dielectric layers or structures may cover antenna  40 , sensor  36 , and/or substrate  170  (e.g., to protect these components from damage or contaminants, to hide these components from view of a user, etc.). 
       FIG. 16  is a graph in which antenna performance (antenna efficiency) has been plotted as a function of operating frequency for antenna  40  of  FIGS. 11-15 . As shown in  FIG. 16 , curve  264  plots an exemplary antenna efficiency of antenna  40  in a free space environment (e.g., in the absence of sensor  36  at end  18  of stylus  10 ). As shown by curve  264 , antenna  40  may exhibit a satisfactory antenna efficiency (e.g., an antenna efficiency above threshold level TH) across a desired frequency range of operation defined by lower frequency FL and upper frequency FH. Lower frequency FL may be approximately 2380 MHz and upper frequency FH may be approximately 2484 MHz in one suitable arrangement (e.g., the frequency range of operation may include a Bluetooth frequency band at 2.4 GHz). 
     Curve  260  plots the antenna efficiency for antenna  40  in the presence of grounded sensor traces  172 . As shown by curve  260 , the presence of grounded sensor traces  172  may load antenna  40  and deteriorate the performance of antenna  40  to unsatisfactory levels between frequencies FL and FH (e.g., to below threshold level TH). Coupling sensor traces  172  to ground using filter circuits such as filter circuits  180  and  200  of  FIGS. 11-14  may serve to electromagnetically isolate antenna  40  from sensor  36  between frequencies FL and FH. This may serve to increase the antenna efficiency of antenna  40  (e.g., as shown by arrow  266 ), so that antenna  40  exhibits an antenna efficiency associated with curve  262  of  FIG. 16 . As shown by curve  262 , antenna  40  may exhibit satisfactory antenna efficiency over the entire frequency range between frequencies FL and FH. In this way, both sensor  36  and antenna  40  may be formed from conductive structures (e.g., conductive traces) on substrate  170  at end  18  of stylus  10  without sacrificing wireless performance for antenna  40  or accuracy for sensor  36 . 
     The example of  FIG. 16  is merely illustrative. In general, antenna  40  may cover any desired bands at any desired frequencies (e.g., antenna  40  may exhibit any desired number of efficiency peaks extending over any desired frequency bands). Curves  260 ,  262 , and  264  may exhibit other shapes if desired. 
     The foregoing is merely illustrative and various modifications can be made by those skilled in the art without departing from the scope and spirit of the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20180227
Publication Date: 20191203
Grant Date: 20191203
Priority Date: 20180227
Inventors: ZHANG, LU
PASCOLINI, MATTIA
JIANG, YI
RAJAGOPALAN, HARISH
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F2203/0384", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/046", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/044", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0383", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/03545", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/03545", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/044", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/03545", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/44", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/44", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/046", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/52", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/03545", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/44", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/044", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/046", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 67685805