PATENT DOCUMENT

Publication Number: US-10627922-B2
Application Number: US-201816143009-A
Country: US
Kind Code: B2

Title: Computer stylus having integrated antenna 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 conductive traces on the substrate may form an antenna ground, an antenna resonating element arm, and a return path. The antenna resonating element arm may be a helical structure that wraps around the substrate. The antenna ground formed from the conductive traces may be coupled to the metal tube using an intermediate metal layer. A cap structure formed at the opposing end and over the substrate may be interposed between the conductive traces and adhesive to protect the conductive traces from the adhesive. A metal portion of the cap structure may serve as an antenna signal reflector.

Claims:
What is claimed is: 
     
       1. 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 and includes a metal tube; 
 a dielectric support structure at the end of the elongated body that extends along the longitudinal axis and has a circumference; 
 an antenna having an antenna resonating element arm on the dielectric support structure, wherein the antenna is configured to transmit radio-frequency signals; 
 an additional dielectric structure that has first and second opposing sides and is attached to the dielectric support structure at the first side; and 
 a reflector structure formed at the second side of the additional dielectric structure and configured to direct the radio-frequency signals towards the tip. 
 
     
     
       2. The computer stylus defined in  claim 1 , wherein the antenna resonating element arm is formed from conductive traces on the dielectric support structure and surrounds at least a portion of the additional dielectric structure. 
     
     
       3. The computer stylus defined in  claim 2 , wherein the conductive traces form a portion of an antenna ground and a return path that couples the portion of the antenna ground to the antenna resonating element arm, and an additional portion of the additional dielectric structure surrounds the conductive traces. 
     
     
       4. The computer stylus defined in  claim 3 , wherein the conductive traces are formed directly on the dielectric support structure. 
     
     
       5. The computer stylus defined in  claim 3 , wherein the portion of the antenna ground is electrically connected to the metal tube through a metal plate. 
     
     
       6. The computer stylus defined in  claim 1 , wherein the antenna resonating element arm on the dielectric support structure wraps more than 180 degrees around the circumference. 
     
     
       7. The computer stylus defined in  claim 1 , further comprising:
 transceiver circuitry that is coupled to the antenna by a transmission line, wherein the dielectric support structure has a groove and the transmission line extends along the groove. 
 
     
     
       8. The computer stylus defined in  claim 1 , further comprising:
 an outer layer that extends along the longitudinal axis and that surrounds the metal tube, wherein the additional dielectric structure is attached to the outer layer. 
 
     
     
       9. 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 includes a metal tube having an opening; 
 a dielectric structure at the end of the elongated body, the dielectric structure having first and second opposing ends and the first end being interposed between the tip and the second end; and 
 conductive traces on the dielectric structure, wherein a first portion of the conductive traces forms an antenna resonating element arm for an antenna and a second portion of the conductive traces on the first end of the dielectric structure forms an antenna ground for the antenna, the first end of the dielectric structure being disposed at an end of the metal tube, and the antenna ground formed by the second portion of the conductive traces is aligned with the opening of the metal tube. 
 
     
     
       10. The computer stylus defined in  claim 9 , wherein the dielectric structure comprises a first portion on which the antenna resonating element arm is formed and a second portion on which a portion of the antenna ground is formed, wherein the second portion extends from the first portion and into the opening of the metal tube. 
     
     
       11. The computer stylus defined in  claim 10 , wherein the second portion of the conductive traces on the first end of the dielectric structure comprises a conductive trace portion on the first portion of the dielectric structure and a conductive trace portion on the second portion of the dielectric structure. 
     
     
       12. The computer stylus defined in  claim 10 , wherein the first portion of the dielectric structure comprises a cylindrical portion having a flat surface extending along the longitudinal axis and the second portion of the dielectric structure comprises a rectangular portion that extends from the cylindrical portion along the longitudinal axis. 
     
     
       13. The computer stylus defined in  claim 9 , further comprising:
 a metal layer that extends across the end of the metal tube and that electrically connects the metal tube to the conductive traces, wherein the metal layer is interposed between the end of the metal tube and the first end of the dielectric structure. 
 
     
     
       14. The computer stylus defined in  claim 13 , further comprising:
 a fastener that biases the metal layer to the first end of the dielectric structure. 
 
     
     
       15. The computer stylus defined in  claim 9 , wherein the dielectric structure extends along a longitudinal axis and has a perimeter about the longitudinal axis, the antenna resonating element arm extends along the perimeter, and the antenna ground extends along the perimeter. 
     
     
       16. A computer stylus, comprising:
 an elongated body having a tip and an opposing end coupled by a shaft that extends along a longitudinal axis, wherein the shaft includes a metal tube and a dielectric outer tube that covers the metal tube; 
 an antenna having an antenna resonating element arm formed on a substrate; and 
 a cap structure having an elongated portion that extends along the longitudinal axis, wherein the elongated portion is interposed between the outer tube and the antenna resonating element arm. 
 
     
     
       17. The computer stylus defined in  claim 16 , wherein the cap structure includes a metal reflector that is configured to reflect radio-frequency signals transmitted by the antenna towards the tip. 
     
     
       18. The computer stylus defined in  claim 17 , wherein the metal reflector comprises a ring-shaped metal reflector. 
     
     
       19. The computer stylus defined in  claim 16 , wherein the elongated portion of the cap structure is attached to the outer tube, the cap structure includes an additional portion that is attached to the substrate. 
     
     
       20. The computer stylus defined in  claim 16 , wherein the substrate comprises an antenna carrier that is interposed between the cap structure and the metal tube.

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 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 and an outer tube that covers the metal tube. 
     The computer stylus may include a dielectric substrate (e.g., a dielectric structure or antenna carrier) at the end of the elongated body and conductive traces or other conductive structures on the dielectric substrate. The dielectric substrate may extend along the longitudinal axis of the shaft and have a circumference or perimeter. An antenna may be formed from the conductive traces. In particular, an antenna resonating element arm formed from the conductive traces may wraps more than 180 degrees around the circumference of the dielectric substrate. As an example, the antenna resonating element arm on the dielectric support structure may also wraps less than 720 degrees around the circumference. 
     The conductive traces may be formed directly on the dielectric support structure. The conductive traces may also form an antenna ground and a return path. A ground antenna feed terminal may be coupled to the antenna ground portion of the conductive traces and a positive antenna feed terminal may be coupled to the antenna resonating element arm. 
     The antenna ground portion of the conductive traces may be coupled to the metal tube using a metal plate. The metal plate may be biased against the dielectric substrate using a fastener. The metal tube may have an opening aligned with the antenna ground portion. Transceiver circuitry may be coupled to the antenna by a transmission line. The dielectric support structure may have a groove and the transmission line may extend along the groove. 
     A cap structure may have an elongated portion that is interposed between the outer tube and the antenna resonating element arm. The elongated portion of the cap structure may be interposed between adhesive material and the dielectric carrier and may surround the dielectric carrier. The cap structure may include a metal reflector for the antenna. The substrate may be interposed between the cap structure and the metal tube. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative computer and associated computer stylus in accordance with some embodiments. 
         FIG. 2  is a schematic diagram of an illustrative stylus with wireless communications circuitry in accordance with some embodiments. 
         FIG. 3  is a diagram of illustrative wireless circuitry for use in a stylus in accordance with some embodiments. 
         FIG. 4  is a diagram of an illustrative inverted-F antenna for a stylus in accordance with some embodiments. 
         FIG. 5  is a perspective view of an illustrative antenna formed using laser direct structuring techniques in accordance with some embodiments. 
         FIG. 6  is a perspective view of an illustrative flexible printed circuit antenna in accordance with some embodiments. 
         FIG. 7  is a perspective view of an illustrative antenna with a metal resonating element mounted to a support structure in accordance with some embodiments. 
         FIG. 8  is a cross-sectional side view of an illustrative antenna formed from printed conductive ink in accordance with some embodiments. 
         FIG. 9  is a cross-sectional side view of a portion of an elongated body for a stylus in accordance with some embodiments. 
         FIG. 10  is a side view of an illustrative stylus having a tip and an opposing end at which an antenna and a cap structure have been formed in accordance with some embodiments. 
         FIG. 11  is a side view of an illustrative antenna formed from conductive traces that surround an antenna carrier in accordance with some embodiments. 
         FIGS. 12A and 12B  are two perspective views of an illustrative antenna formed from conductive traces that surround an antenna carrier in accordance with some embodiments. 
         FIG. 13  is a perspective view of an antenna carrier coupled to grounding structures in a stylus in accordance with some embodiments. 
         FIG. 14  is a perspective view of an assembled antenna in a stylus in accordance with some embodiments. 
         FIG. 15  is a cross-sectional view of an antenna having structures integrated with a cap structure in a stylus in accordance with some embodiments. 
         FIGS. 16A and 16B  are top views of metal reflectors in cap structures for a stylus in accordance with some embodiments. 
         FIG. 17  is a graph of antenna performance (e.g., antenna efficiency) for an antenna of the type shown in  FIGS. 11-15  in accordance with some embodiments. 
     
    
    
     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  or elsewhere in stylus  10  may, for example, generate touch or proximity sensor data indicative of whether or not end  18  or other portions of stylus  10  are being pressed against display  24  of tablet computer  20 , force sensor data indicative of how hard end  18  or other portions of stylus  10  are 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, NFC 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, matching circuitry, 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 hands, 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. Storage and processing circuitry  30  may generate sensor data based on the sensor signals received over sensor data path  86 . Storage and processing 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 storage and processing 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. Inkjet 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, layer  156  may be formed from metal, plastic, carbon fiber, ceramic, or other materials, layer  158  may be formed from metal, plastic, carbon fiber, ceramic, or other materials, and layer  160  may be formed from metal, plastic, carbon fiber, ceramic, or other materials. With another illustrative arrangement, inner layer  160  may be omitted, layer  156  may be formed from metal, plastic, or other materials and layer  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. If desired, layers  156 ,  158 , and  160  may be tubular but not completely concentric. As an example, layer  158  may have a shape that accommodates for other components in stylus  10 , such as a cylindrical shape with a flattened surface extending along the longitudinal axis, a cylindrical shape having windows or cavity portions extending along the longitudinal axis, etc. 
     As shown in the 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. Antenna  40  may be formed using metal structure 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 form antenna  40  may include, for example, conductive traces that form antenna resonating element  106  of  FIG. 4 , antenna ground  104  of  FIG. 4 , and/or any other antenna structures. 
     If care is not taken, metal structures in stylus  10  may interfere with the operation of antenna  40 . Other limitation such as the compactness of stylus  10  may also restrict the configuration of antenna  40  in stylus  10 . To provide satisfactory antenna performance, stylus  10  may include antenna  40  that is integrated with (e.g., have common shared structures with, overlaps with, surrounded by, coupled to, etc.) other portions of stylus  10 . As an example, stylus  10  may include cap structure  170  (sometimes referred to herein as a cap) formed at end  18 . If desired, cap structure  170  may be integrated with antenna  40  (e.g., integrated with an antenna carrier on which antenna traces for antenna  40  are formed). In other words, portions of cap structure  170  may overlap portions of antenna  40 . If desired, portions of cap structure  170  may enhance the performance of antenna  40  (e.g., serve as a reflector for antenna  40  to direct antenna signals in a particular direction), may encase antenna  40  to protect antenna  40  from contaminants, may surround antenna  40  to form a compact integrated structure, etc. 
     If desired, antenna  40  may also be coupled with (e.g., integrated with or share integral structures with) other structures in stylus  10  such as one or more of layers  156 ,  158 ,  160  ( FIG. 9 ), components  8  ( FIG. 1 ), sensors  36  ( FIG. 2 ), etc. In particular, the metal structures that form the antenna ground for antenna  40  may be shorted (e.g., grounded) to layer  158  ( FIG. 9 ) in scenarios where layer  158  is formed from metal. Layer  158  may sometimes be referred to herein as metal tube  158 . However, if desired, layer  158  may be formed from any other material such as a non-metallic conductive structure, may be a non-cylindrical structure, etc. 
       FIG. 11  is a side view of an illustrative antenna (e.g., antenna  40  in stylus  10 ). In particular, antenna  40  may be formed from conductive traces  180  on an antenna carrier  178  (sometimes referred to herein as a substrate, a support structure, a dielectric support structure, or an antenna support structure). Antenna carrier  178  may be formed from a single block of dielectric material, a combination of two or more dielectric materials of different types, or may be formed at least partially from materials that are not dielectric materials. Antenna carrier  178  may have a cylindrical shape, a rectangular shape, an elongated shape, an irregular shape that is a combination of two or more shapes, or may have any other desired shapes. In the example of  FIG. 11 , antenna carrier  178  has a cylindrical antenna carrier portion  178 - 1  extending along longitudinal axis  172  with a flat rectangular surface  179  on one side of the cylindrical antenna carrier portion. Antenna carrier  178  may have a protruding rectangular portion such as protruding antenna carrier portion  178 - 2  that extends from an end of cylindrical antenna carrier portion  178 - 1  along longitudinal axis  172 . Cylindrical antenna carrier portion  178 - 1  and protruding antenna carrier portion  178 - 2  may share flat rectangular surface  179 . In other words, antenna carrier  178  may have a length that extends across antenna carrier portions  178 - 1  and  178 - 2  along longitudinal axis  172 . Antenna carrier  178  may also have one or more different circumferences about longitudinal axis  172  (e.g., a circumference for cylindrical antenna carrier portion  178 - 1 ). The circumference (perimeter) may be circular, have one or more curved portions and one or more straight portions, or may have only straight portions (e.g., cylindrical antenna carrier portion  178 - 1  need not be perfectly cylindrical). As an example, longitudinal axis  172  for antenna carrier  178  may be aligned with or parallel to longitudinal axis  12  for stylus  10  ( FIG. 1 ). This is merely illustrative. If desired, antenna carrier  178  may have any suitable shape and may have one or more recesses and/or protrusions. 
     As an example, conductive traces  180  may be formed using LDS (e.g., some or all of conductive traces  180  may be deposited by electroplating metal directly onto antenna carrier  178 ) In particular, conductive traces  180  may form at least a portion of antenna ground  104 . A first portion of antenna ground  104  may be formed on cylindrical antenna carrier portion  178 - 1 . A second portion of antenna ground  104  may be formed on protruding antenna carrier portion  178 - 2 . Allowing antenna ground  104  to extend onto protruding antenna carrier portion  178 - 2  can provide improved grounding properties for antenna  40  and can facilitate connection to other grounding structures and/or transmission line structures in stylus  10  relative to scenarios in which antenna ground  104  is only formed on cylindrical antenna carrier portion  178 - 1 , for example. However, this is merely illustrative. If desired, antenna ground  104  may be formed entirely on cylindrical antenna carrier portion  178 - 1  or entirely on protruding antenna carrier portion  178 - 2 . 
     Conductive traces  180  may form antenna resonating element arm  108 . Antenna resonating element arm  108  may surround antenna carrier  178  (e.g., at cylindrical antenna carrier portion  178 - 1 ) and may extend around the circumference of antenna carrier  178  while also extending along longitudinal axis  172  (e.g., in a winding, spiral or helical pattern). In other words, resonating element arm  108  may form a helical structure that wraps around antenna carrier  178  at least once. Conductive traces  180  may form return path  110  that couples antenna ground  104  to antenna resonating element arm  108 . As an example, return path  110  may extend along longitudinal axis  172  of antenna carrier  178  and may be formed on a curved surface of antenna carrier  178 . Antenna  40  may include antenna feeds such as positive antenna feed terminal  98  and ground antenna feed terminal  100 . If desired, a groove such as groove  182  may be formed in antenna carrier  178  (e.g., extending along longitudinal axis  172 ). Positive antenna feed terminal  98  may be coupled to antenna resonating element arm  108  at groove  182 . Ground antenna feed terminal  100  may be coupled to antenna ground  104  at groove  182 . If desired, multiple ground antenna feed terminals may be coupled to antenna ground  104  at respective locations along groove  182 . If desired, other components may extend along groove  182 . Groove  182  may extend only partially along the length of antenna carrier  178  if desired, as shown in  FIG. 11 . Alternatively, if desired, groove  182  may extend completely along the length of antenna carrier  178 . 
       FIGS. 12A and 12B  are perspective views of antenna  40  on antenna carrier  178 . In particular, antenna carrier  178  may have surfaces  179 ,  181 ,  183 , and  185 . As shown in  FIGS. 12A and 12B , surfaces  179 ,  183 , and  185  may each extend along longitudinal axis  172 , whereas surface  181  may be oriented perpendicular to longitudinal axis  172 . As shown in  FIGS. 12A and 12B , antenna ground  104  may be formed on surfaces that extend along longitudinal axis  172  such as surface  179  and surface  183  adjacent to surface  179 . Antenna ground  104  may also be formed on surfaces that are perpendicular to longitudinal axis  172  such as surface  181 . In other words, antenna ground  104  may completely cover one end of antenna carrier portion  178 - 1 . The example of  FIGS. 12A and 12B  in which antenna ground  104  is formed on surfaces  179 ,  181 ,  183 , but not on surface  185  that opposes surface  179 , is merely illustrative. If desired, antenna ground  104  may be formed on only one surface of antenna carrier  178 , only two surfaces of antenna carrier  178 , or three or more surfaces of antenna carrier  178 . 
     Antenna resonating element arm  108  may be formed on surfaces  183  and  179  of antenna carrier portion  178 - 1 . In particular, antenna resonating element  108  may wrap around antenna carrier  178  along surfaces  179  and  183 . Surfaces  179  and  183  may define a circumference (perimeter) of antenna carrier  178  about longitudinal axis  172 . If desired, resonating element arm  108  may extend more than 360 degrees in rotational direction  174  about longitudinal axis  172  (e.g., arm  108  may have a length longer than the circumference of antenna carrier  178 ), may extend more than 180 degrees in rotational direction  174  about longitudinal axis  172 , etc. This is merely illustrative. If desired, resonating element arm  108  may only partially wrap around antenna carrier  178  (e.g., may extend less than 360 degrees in rotational direction  174  about longitudinal axis  172 ), may wrap around antenna carrier  178  more than once, more than twice, or more than three times, more than once but less than twice (e.g., may extend more than 360 degrees but less than 720 degree about longitudinal axis  172 ), etc. 
     Antenna resonating element arm  108  and antenna ground  104  may be formed at opposing ends of antenna carrier  178 . In particular, one end of antenna resonating element arm  108  may be connected to antenna ground  104  using return path  110  (e.g., on surface  183 ). Antenna resonating element arm  108  may extend downward on one side of antenna carrier  178  on surface  183 , across surface  179 , upward on the opposing side of antenna carrier  178  on surface  183 , downward on the one side of antenna carrier  178  a second time on surface  183 , and partially across surface  179 . Antenna resonating element arm  108  may terminate at surface  179 . This is merely illustrative. If desired, antenna resonating element arm  108  may terminate on any side of antenna carrier  178  and/or any surface of antenna carrier  178 . If desired, antenna resonating element arm  108  may extend from return path  110  in an opposite direction than as depicted in  FIGS. 12A and 12B . Because antenna resonating element arm  108  extends in a helical pattern around antenna carrier  178 , antenna  40  may sometimes be referred to herein as a helical antenna with a return path or a helical-type IFA antenna. 
     Groove  182  in antenna carrier  178  ( FIG. 11 ) may extend at least partially through the length of antenna carrier  178 . Surfaces  179  and  185  may have a curved portion that defines a shape of groove  182 . If desired, groove  182  may be formed at the interface between surface  179  and surface  183 . 
     Antenna carrier  178  may have a protrusion on surface  181  (e.g. alignment pin  186 ) and a depression on surface  181  (e.g., hole  184 ). Alignment pin  186  may align antenna carrier  178  to other structures (e.g., additional grounding structures connected to antenna ground  104  form from conductive traces  180 ). Hole  184  may accommodate a screw used to connect the other structures to antenna carrier  178  at the end where antenna ground conductive traces are formed. 
       FIG. 13  is an exploded perspective view of an antenna having an antenna ground coupled to grounding structures in a stylus. As shown in  FIG. 13  and described previously in connection with  FIGS. 11, 12A, and 12B , antenna ground  104  includes a portion of conductive traces  180  on an antenna carrier  178 . The conductive traces  180  that form antenna ground  104  may be coupled to a tubular metal structure such as metal tube  158  and an interposing metal layer such as metal plate  190 . In particular, metal layer  190  (sometimes referred to herein as a metal plate or a flange) may have openings  192  and  194 , which align with hole  184  and alignment pin  186 , respectively. Metal layer  190  may have a shape that mates with surface  181  and may have an outline that follows a cross-sectional footprint of antenna carrier  178 . An attachment structure such as a fastener (e.g., screw  196 ) may extend through opening  192  to hole  184 . The fastener may bias metal layer  190  against surface  181  of antenna carrier  178 . In this configuration, metal layer  190  may lie on top of surface  185  of antenna carrier  178 . However, this is merely illustrative. 
     Metal layer  190  may be attached to metal tube  158  at attachment points  198 . As an example, metal layer  190  may be welded to metal tube  158  at welding points along the circular outline of metal layer  190  and metal tube  158  (e.g., at points  198 , at additional points along the perimeter of metal layer  190  and at corresponding points along the end of metal tube  158 ). 
     Metal tube  158  may have an opening (e.g., opening  200 ) at the bottom side of the end of metal tube  158 . Opening  200  may accommodate antenna carrier portion  178 - 2 . The attachment and alignment structures described in  FIG. 13  are merely illustrative. If desired, metal layer  190 , metal tube  158 , and antenna carrier  178  may be attached at any suitable location and using any suitable structures such as solder, adhesive, pins, springs, etc. 
       FIG. 14  is a perspective view of antenna  40  assembled with grounding structures and other structures in a stylus (e.g., by collapsing the exploded view of  FIG. 13 ). As shown in  FIG. 14 , metal layer  190  may be interposed between metal tube  158  and antenna carrier  178 . In particular, metal layer  190  may electrically connect the antenna ground portions of conductive traces  180  on antenna carrier  178  to metal tube  158 . Metal tube  158  may span the length of shaft portion  16  in stylus  10 , as an example. Wireless communications circuitry  34  such as transceiver circuits  38  in  FIG. 2  may be provided on the interior of metal tube  158  (e.g., on a substrate within interior cavity  152  in  FIG. 9 ). Transmission line structures such as transmission line path  64  may extend from wireless transceiver circuits  38 , along metal tube  158 , and to conductive traces  180  on antenna carrier  178 . Transmission line path  64  may extend along and within groove  182  in antenna carrier  178 . As an example, transmission line path  64  may be a transmission line having a ground signal conductor. The ground signal conductor may be coupled to ground feed terminal  100 . The ground signal conductor may be connected to multiple points in groove  182  along the antenna ground portion of conductive traces  180 . The transmission line may have a positive signal conductor. The positive signal conductor may be coupled to the positive feed terminal  98  along the antenna resonating element arm portion of conductive traces  180 . 
     Opening  200  in metal tube  158  may serve as a window that exposes the antenna ground portion of conductive traces  180  (e.g., along antenna carrier portion  178 - 2 ). In other words, metal tube  158  may be non-overlapping with respective to any part of the antenna ground portion of conductive traces  180 . As an example, opening  200  may be formed at an end of metal tube  158 . Additionally, metal plate  190  may be coupled to metal tube  158  at the end of metal tube  158 . Antenna carrier  178  and conducive traces  180  may protrude from the end of metal tube  158  and from metal plate  190 . As such, a portion of antenna carrier  178  (e.g., portion  178 - 1  in  FIG. 11 ) may extend from metal plate  190  and a portion of antenna carrier  178  (e.g., portion  178 - 2  in  FIG. 11 ) may be aligned with opening  200 . 
       FIG. 15  is a cross-sectional view of stylus  10  at end  18  in which a cap structure is integrated with antenna structures formed on metal plate  190  and metal tube  158 . In particular, cap structure  170  may be the topmost portion of stylus  10  (e.g., a portion of stylus  10  most distant from tip  14  in  FIG. 1 ). As shown in  FIG. 15 , cap structure  170  may have elongated portions that extend into cavities of antenna carrier  178 . In particular, elongated portions  170 - 1  of cap structure  170  may extend from a bottom surface of cap structure  170  and extend into cavities of antenna carrier  178 . Cap structure  170  may include additional elongated portions  170 - 3  that extend from the same bottom surface of cap structure  170 . Elongated portions  170 - 3  may be interposed between outer tube  156  and antenna carrier  178 . As an example, elongated portions  170 - 3  may surround antenna carrier  178  on all peripheral sides of antenna carrier  178 . 
     Cap structure  170  may include a metal structure such as metal structure  170 - 2 . Metal structure  170 - 2  may be formed along a top surface of cap structure  170 . Metal structure  170 - 2  may be a circular metal layer formed as part of the exterior surface of stylus  10 . In another suitable arrangement, a dielectric coating or other layer may be placed over metal structure  170 - 2 . As shown in  FIG. 16A , metal structure  170 - 2  may have a circular profile when viewed from direction  206  in  FIG. 15 . Returning to  FIG. 15 , metal structure  170 - 2  may be bent to accommodate a suitable shape of stylus  10 , if desired (e.g., metal structure  170 - 2  may be curved, spherical, aspherical, dome-shaped, etc.). 
     Metal structure  170 - 2  may serve as a reflector for antenna signals transmitted by antenna  40  in stylus  10 . As an example, metal structure  170 - 2  may re-direct antenna signals (e.g., signal  204 ) in a downward direction towards tip  14  of stylus  10  and toward device  20  of  FIG. 1 . Metal structure  170 - 2  may be at floating potential (e.g., metal structure  170 - 2  may be electrically isolated from other conductors in stylus  10  and is not grounded). 
     If desired, metal structure  170 - 2  may be a ring structure instead of a bent circular structure as depicted in  FIG. 15 . In particular,  FIG. 16B  shows how cap structure may include a metal ring such as metal ring structure  170 - 4  having a ring shape when viewed from direction  206  as indicated in  FIG. 15 . As an example, the center of metal ring structure may be filled with dielectric material when used to form cap structure  170 . By using metal structure  170 - 2  (or metal structure  170 - 4 ) as a reflector, the performance of antenna  40  may be enhanced (e.g., the radiation pattern of antenna  40  may be more directional towards tip  14  and/or device  20  of FIG.  1 ). If desired, all other portions of cap structure  170  besides metal structure  170 - 2  (or metal structure  170 - 4 ) may be formed from dielectric or non-conductive material. If desired, structures  170 - 2  and  170 - 4  may be formed from nonmetallic conductive material. These structures may have other shapes if desired. 
     Returning to  FIG. 15 , adhesive material such as adhesive  202  may attach cap structure  170 , antenna carrier  178 , metal tube  158 , outer layer  156 , and any other structures in stylus  10  to each other. As an example, adhesive  202  may be formed at a cavity in antenna carrier  178 . As another example, adhesive  202  may be formed along outer tube  156 . This is merely illustrative. If desired, adhesive  202  may be formed at any suitable location in stylus  10 . 
     Portions of cap structure may be interposed between portions of adhesive  202  and conductive traces  180  or otherwise be placed to protect conductive traces  180  from contamination. As an example, cap portion  170 - 3  may be interposed between adhesive  202  and conductive traces  180  on one or more sides of antenna carrier  178 . As another example, cap portion  170 - 2  may extend into adhesive  202  at a cavity in antenna carrier  178  to prevent adhesive from flowing onto conductive traces  180  (e.g., to hold adhesive  202  in place in the antenna carrier cavity). 
     If desired, cap structure  170  or portions of cap structure  170  (e.g., metal structure  170 - 2 , elongated portions  170 - 1  and  170 - 3 , etc.) may have rotational symmetry about a longitudinal axis or reflective symmetry across one or more central planes. In other words, cap structure  170  may completely surround antenna carrier  178  except on a bottom side adjacent to metal layer  190  (e.g., may surround antenna carrier  178  on a top side and all peripheral sides of antenna carrier  178 ). These examples are merely illustrative. If desired, cap structure  170  may only partially surround antenna carrier  178  on the top and/or peripheral sides. 
       FIG. 17  is a graph in which antenna performance (e.g., antenna efficiency) has been plotted as a function of operating frequency for antenna  40  of  FIGS. 11-15 . As shown in  FIG. 17 , curve  210  plots an exemplary antenna efficiency of an antenna in a first operating environment (e.g., in the absence of metal structure  170 - 2 , in the absence of window  200  in metal tube  158 , without coupling antenna ground to additional grounding structures, etc.) between frequencies F L  and F H . In the presence of metal structure  170 - 2  in cap structure  170 , additional grounding structures in stylus  10 , and antenna window in metal tube  158 ), the antenna efficiency of antenna  40  as described in connection with  FIGS. 11-15  may improve (as indicated by arrow  218 ) to curve  220 . Frequencies F L  and F H  may correspond to edges of a Bluetooth frequency band, as just one example. 
     The example of  FIG. 17  is merely illustrative. In general, antenna  40  may be used to 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  210  and  220  may exhibit other shapes if desired. 
     In this way, a stylus may be provided with an antenna having an antenna resonating element, a return path, and an antenna ground formed from conductive traces on an antenna carrier. The conductive traces may be coupled to additional grounding structures in the stylus to improve antenna efficiency. Additionally, portions of a cap structure may include an antenna reflector to further improve antenna efficiency towards the tip of the stylus. The cap may also serve to protect the antenna from adhesive used to hole structures together within the stylus. By providing these structures in an integrated configuration, satisfactory antenna performance may be achieved within a frequency band of interest in a compact form factor such as a housing for a computer stylus. 
     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: 20180926
Publication Date: 20200421
Grant Date: 20200421
Priority Date: 20180926
Inventors: ZHANG, LU
JIANG, YI
PASCOLINI, MATTIA
Assignee: APPLE INC
CPC Classifications: [{"code": "H01Q1/362", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/38", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/03545", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/2258", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/044", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01Q19/027", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01Q1/38", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/038", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/03545", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F2203/0384", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/038", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/03545", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/38", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q19/027", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/044", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F2203/0384", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01Q9/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/48", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/03545", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/2258", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/03545", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 69884850