PATENT DOCUMENT

Publication Number: US-8428287-B2
Application Number: US-49978509-A
Country: US
Kind Code: B2

Title: Earbuds with electrostatic discharge protection

Abstract:
To avoid undesirable electrostatic discharge events while maintaining low leakage currents, earbuds may be provided with controlled electrostatic discharge paths. The discharge paths may include discrete components such as resistors or more distributed resistive components such as resistive elastomers. A resistive elastomer may be incorporated into an interior portion of an earbud between an earbud housing structure and a ground path. A resistive elastomer may also be used in forming an ear bud tip.

Claims:
What is claimed is: 
     
       1. Earbud headphones, comprising:
 at least one earbud having a metal earbud housing structure; 
 an audio connector; 
 at least one speaker driver; 
 a cable having a positive signal line and a ground line, wherein the cable conveys audio signals for the at least one speaker driver from the audio connector to the at least one earbud; and 
 an electrostatic discharge path that has an associated resistance through which electrostatic charge on the metal earbud housing structure is discharged into the ground line, wherein at least a portion of the electrostatic discharge path is interposed between the at least one speaker driver and the metal earbud housing structure. 
 
     
     
       2. The earbud headphones defined in  claim 1  wherein the electrostatic discharge path includes a discrete resistor that provides the resistance. 
     
     
       3. The earbud headphones defined in  claim 1  further comprising a nonconductive barrier structure between the metal earbud housing structure and the speaker driver, wherein the electrostatic discharge path includes a discrete resistor that is mounted within the nonconductive barrier structure to provide the resistance. 
     
     
       4. The earbud headphones defined in  claim 1  wherein the electrostatic discharge protection path comprises a resistive member that provides the resistance. 
     
     
       5. The earbud headphones defined in  claim 4  wherein the resistive member comprises an elastomeric substance. 
     
     
       6. The earbud headphones defined in  claim 4  wherein the resistive member comprises a rubber boot that surrounds the speaker driver. 
     
     
       7. The earbud headphones defined in  claim 4  wherein the resistive member comprises an elastomeric substance interposed between the metal earbud housing structure and the speaker driver. 
     
     
       8. The earbud headphones defined in  claim 7  wherein the elastomeric substance has a resistance of between 30 MΩ and 1 MΩ. 
     
     
       9. The earbud headphones defined in  claim 7  wherein the speaker driver comprises a metal speaker driver housing and wherein the earbud headphones further comprise conductive epoxy in the electrostatic discharge path, wherein the conductive epoxy is connected to the metal speaker driver housing. 
     
     
       10. The earbud headphones defined in  claim 9  further comprising a printed circuit board with a ground trace that is shorted to the ground line, wherein the conductive epoxy is shorted to the ground trace. 
     
     
       11. The earbud headphones defined in  claim 10  further comprising speaker crossover circuitry on the printed circuit board. 
     
     
       12. The earbud headphones defined in  claim 11  further comprising a high-frequency driver and a low-frequency driver in the metal speaker driver housing. 
     
     
       13. The earbud headphones defined in  claim 1  wherein the speaker driver comprises a metal speaker driver housing, wherein at least part of the metal earbud housing structure surrounds the metal speaker driver housing, and wherein the electrostatic discharge path comprises a ring of elastomeric material with a non-zero conductivity that is interposed between the metal earbud housing structure and the metal speaker driver housing. 
     
     
       14. Earbud headphones, comprising:
 an audio plug; 
 a cable connected to the audio plug that contains signal lines and a ground line; and 
 a pair of earbuds, each earbud containing a speaker driver, a conductive earbud housing member in which the speaker driver is mounted, and a resistive material interposed between the earbud housing member and the ground line that serves as an electrostatic discharge path to the ground line, wherein at least a portion of the resistive material is interposed between the earbud housing member and the speaker driver. 
 
     
     
       15. The earbud headphones defined in  claim 14  wherein the resistive material comprises an elastomer with a non-zero conductivity. 
     
     
       16. The earbud headphones defined in  claim 14  wherein the speaker driver in each earbud is enclosed within a metal speaker driver housing and wherein the resistive material surrounds the metal speaker driver housing. 
     
     
       17. The earbud headphones defined in  claim 16  wherein the conductive earbud housing member in each earbud surrounds and contacts the resistive material. 
     
     
       18. The earbud headphones defined in  claim 16  further comprising a printed circuit board in each earbud containing a ground trace to which the metal speaker driver housing of that earbud is shorted. 
     
     
       19. The earbud headphones defined in  claim 18  further comprising solder that connects the metal speaker driver housing in each earbud to the ground trace on the printed circuit board of that earbud. 
     
     
       20. An earbud for a pair of earbud headphones having a cable with a ground path, comprising:
 at least one speaker; 
 an elastomeric earbud member that is adapted to fit into an ear canal of a user; 
 a conductive earbud housing structure to which the elastomeric earbud member is connected; and 
 an electrostatic discharge path between the conductive earbud housing structure and the ground path having a resistance of between 300 kΩ and 40 MΩ, wherein at least a portion of the electrostatic discharge path is positioned between a portion of the conductive earbud housing structure and a portion of the at least one speaker. 
 
     
     
       21. The earbud defined in  claim 20  further comprising a ring-shaped elastomeric structure that is interposed between the conductive earbud housing structure and the ground path and that forms at least part of the electrostatic discharge path. 
     
     
       22. The earbud defined in  claim 21  wherein the speaker is one of a pair of first and second speaker drivers each of which handles audio signals in a different respective frequency and each of which is mounted in a respective one of two metal speaker driver housings, the earbud further comprising solder that shorts the two metal speaker driving housings to each other, wherein the metal speaker driver housings form at least part of the electrostatic discharge path.

Description:
BACKGROUND 
     Headphones are used to play audio for users of electronic devices with media playback capabilities. For example, a pair of headphones may be used to play music for a user of a media player or may handle audio for a cellular telephone user. 
     Traditional headphones have relatively large ear cups. More recently, smaller headphones known as earbuds have been developed. In some earbud-style headphones, a small plastic earpiece rests in the outer ear canal of the user. Other earbuds have elastomeric earpieces that fit snuggly within a user&#39;s ear canal. 
     Earbuds are used in a variety of environments. For example, earbuds may be plugged into computers or other electronic equipment that is powered from a wall outlet. Earbuds are also used in static-filled environments such as airplanes. Earbuds are sometimes handled roughly, so durability is a concern. 
     These possible operating environments impose constraints on earbud designers. For example, a durable earbud that is formed from metal parts may be susceptible to electrostatic discharge. Electrostatic charge develops on a user in the course of a user&#39;s normal activities. As static electricity builds up on a user&#39;s ear, an electrostatic potential can develop across insulating portions of an earbud such as an elastomeric earpiece. If the amount of charge that develops is large enough, an electrostatic discharge event will occur. During the electrostatic discharge event, charge buildup will be released as charge flows across the insulating portions of the earbud. This may produce a spark that is felt by the user or may produce an audible crackle as the charge interacts with the speaker driver in the earbud. 
     Sparks and audible interference can be unpleasant for users. Although some of these effects can be mitigated by forming earbuds entirely from plastic, conventional all-plastic earbud designs tend not to be aesthetically appealing and may not be sufficiently durable to withstand rough handling. Some conventional earbuds address the effects of electrostatic discharge events by shorting their positive audio lines to metal driver parts in the earbuds. This approach may not be optimal when the earbuds are used with wall-powered equipment, because the positive audio line could potentially become shorted to a live power supply line if the wall-powered equipment were to develop an electrical fault. 
     It would therefore be desirable to be able to provide earbuds that are able to safely mitigate the effects of electrostatic discharge events. 
     SUMMARY 
     Earbuds may be prone to electrostatic discharge events. During an electrostatic discharge event, static charge that is accumulated on a conductive earbud housing or other conductive structure may discharge to a part of the human body (e.g., a user&#39;s ear). To avoid undesirable electrostatic discharge events, earbuds may be provided with electrostatic discharge paths. 
     An earbud may contain a metal speaker driver housing in which a speaker driver is mounted. The earbud may also have a printed circuit board on which electrical components such as speaker crossover circuits for the speaker driver are mounted. The crossover circuits may be used to route audio signals to low-frequency and high-frequency speakers in the metal speaker driver housing. 
     A pair of earbuds may have an audio plug and associated cable. Signal lines and a ground line in the cable may be used to connect the audio plug to each earbud. In each earbud, the ground line may be connected to ground traces on the printed circuit board to which the crossover elements are mounted. A conductive epoxy may be used to electrically short the ground trace on the printed circuit board to the metal speaker driver housing. 
     The electrostatic discharge path in each earbud may be formed from an elastomer or other material interposed between the conductive earbud housing and the metal speaker driver housing and ground trace. The elastomer or other electrostatic discharge material may have a resistance that is sufficiently high to avoid undesirable leakage currents but that is sufficiently low to allow electrostatic charge from the conductive earbud housing to discharge to ground. 
     Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative set of earbud headphones accordance with an embodiment of the present invention. 
         FIG. 2  is a cross-sectional view of an illustrative earbud with a resistive material that provides a controlled discharge path for electrostatic charge in accordance with an embodiment of the present invention. 
         FIG. 3  is a cross-sectional view of another illustrative earbud with a resistive material that provides a controlled discharge path for electrostatic charge in accordance with an embodiment of the present invention. 
         FIG. 4  is a cross-sectional view of an interior portion of an earbud with a resistive elastomer that serves as an electrostatic discharge path in accordance with an embodiment of the present invention. 
         FIG. 5  is a cross-sectional view of an interior portion of an earbud showing how a driver housing member may be soldered to a ground trace on a driver printed circuit board in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Media players and electronic devices such as cellular telephones, computers, and other electronic equipment may be used to play media content and present other audio content to a user. Some electronic devices have no internal audio playback capabilities, but can play back audio through an attached set of headphones. Other electronic devices are provided with internal speakers, but still contain audio jacks into which headphones can be plugged when it is desired to use headphones in place of the internal speakers. 
     Many popular headphones use earbud-style earpieces. Earbuds are more compact than traditional over-the-ear headsets and, particularly when provided with elastomeric in-ear earpieces, can help provide sound isolation. 
     Some conventional earbuds are formed almost entirely of insulating materials such as plastic. These devices tend to resist electrostatic discharge, but can be unsightly and fragile. 
     Other conventional earbuds may include durable metal parts over which soft elastomeric earpieces are formed, but are subject to electrostatic discharge events or use sub-optimal connections for their signals lines. 
     A set of earbud headphones having a design that helps to mitigate electrostatic discharge effects is shown in  FIG. 1 . As shown in  FIG. 1 , earbud headphones  10  may have a cable  12 , earbuds  14 , and an audio connector such as audio plug  16 . Audio plug  16  may mate with a corresponding jack such as jack  20  in electronic device  18 . 
     Audio plug  16  and mating audio jack  20  can be provided in a variety of form factors. For example, audio jacks and plugs can have different sizes (e.g., ¼″, ⅛″ or 3.5 mm, etc.). Audio jacks and plugs can also have different numbers of contacts. For example, audio connectors such as these may have two contacts for audio and ground or may have three contacts to support left and right stereo audio signals and ground. Some audio connector arrangements use four or more audio connectors. For example, a four-contact connector may have left and right audio contacts, a microphone contact, and a ground contact. 
     A typical three-pin audio connector has a tip contact, a ring contact, and a sleeve contact and is therefore sometimes referred to as a tip-ring-sleeve (TRS). A four-pin audio connectors may have a tip, two rings, and a sleeve. Four-pin audio connectors are therefore sometimes referred to as tip-ring-ring-sleeve (TRRS) connectors. These audio connector arrangements or other suitable audio connector arrangements may be used in headphones  10  if desired. 
     Device  18  may be a media player, a cellular telephone player with media player capabilities, a portable electronic device such as a computer, a smaller portable electronic device such as a pendant or wrist device, or any other suitable electronic device. 
     The functions of device  18  may be implemented using storage and processing circuitry. Storage in the storage and processing circuitry may include volatile and non-volatile memory and may be provided using stand-alone memory chips, memory that is incorporated into a processor, application-specific integrated circuit, or other component, solid state memory devices, hard drives, or other suitable storage components. Processing circuitry in the storage and processing circuitry may be implemented using one or more processors. Examples of integrated circuits that may be used in providing processing capabilities for device  18  include microprocessors, microcontrollers, digital signal processors, audio and video chips (codecs), application-specific integrated circuits, communications circuits, etc. 
     Cable  12  may include two, three, four, or more than four conductive wires. Cables with fewer wires may only be able to support monaural audio. Cables with more wires may be able to support more advance functions, such as stereo audio, microphone signals for voice calls, and data signals (e.g., for user input from a user input device or for user output for a status indicator). Cable  12  in the example of  FIG. 1  has three wires for left audio, right audio, and a shared ground. This type of arrangement is, however, merely illustrative. Cable  12  may, in general, have any suitable number of conductive lines each of which may be connected to a respective conductive contact in audio connector  16 . 
     Earbuds  14  contain speaker drivers. Each earbud  14  may contain a single driver or each earbud may contain two or more driver elements. For example, high-quality audio may be played back for a user with a two-speaker arrangement. In a typical two-speaker arrangement, each earbud  14  may contain a woofer driver for reproducing low frequencies and a tweeter driver for reproducing high frequencies. Other arrangements may be used if desired (e.g., with midrange drivers, subwoofers, etc.). 
     Earbuds  14  may be constructed from conductive materials such as metal (including elemental metals and metal alloys) and from insulating structures such as plastic and elastomeric substances. In earbuds that fit in the outer portions of a user&#39;s ear, it may be acceptable to use rigid polymers such as acrylonitrile butadiene styrene (ABS), polycarbonate (PC), or PC/ABS blends or other relatively hard materials to form earbud structures. In earbuds that fit within the ear canal of a user (sometimes referred to as in-canal or in-ear earbuds), it may be desirable to form the part of the earbud that contacts the user&#39;s ear from a soft elastomer such as foam or silicone. 
     To ensure sufficient durability and to enhance aesthetics, it may be desirable to form at least part of earbuds  14  from a conductor such as metal. For clarity, earbud arrangements in which part of the earbud is formed from metal and part of the earbud is formed from an insulator such as a soft elastomer or rigid plastic are described herein as examples. In the example of  FIG. 1 , each earbud has a metal housing portion  14 A and an insulating portion  14 B. Housing portions  14 A may be formed from stainless steel or other suitable metals. Insulating portion  14 B may be formed from silicone, foam, or other elastomeric substances (as examples). 
     A partly schematic cross-sectional side view of one of earbuds  14  is shown in  FIG. 2 . As shown in  FIG. 2 , audio jack  16  may be connected to wires  22  and  24  in cable  12 . Only one channel of audio is being handled in the example of  FIG. 2 , so there is a single audio line (positive line  24 ) and a corresponding ground (ground line  22 ) depicted in the drawing. 
     Lines  24  and  22  may be routed to corresponding positive speaker driver terminal  30  and ground speaker driver terminal  28  on speaker driver  26 . Speaker driver  26  may contain one or more speakers that produce sound for earbud  14 . 
     Portion  14 A of earbud  14  may be formed of metal. Portion  14 B may be formed of an insulator such as an elastomer or a rigid plastic. Because portion  14 B is often formed from elastomeric materials, portion  14 B of earbud  14  is sometimes referred to herein as elastomeric ear-canal structure  14 B. 
     Structure  14 B has openings to allow sound to escape from the interior of earbud  14 . In particular, structure  14 B has an interior channel  46  that terminates in exterior opening  42 . Interior channel  46  may be a hollow cylinder and exterior opening  42  may be a circular hole (as examples). 
     Electrostatic charge can build up on earbud  14  during use. For example, in the absence of a suitable electrostatic discharge path, portion  14 A might become charged when contacted by a user&#39;s ear. 
     To prevent excessive amounts of electrostatic charge from developing and thereby prevent electrostatic discharge events, headphones  10  may be provided with a controlled electrostatic discharge path. The discharge path may be formed within portions of the headphones such as cable  12  and plug  16  or, more preferably, as part of earbud  14 . With one suitable arrangement, which is sometimes described herein as an example, earbud  14  may be provided with structures that form a resistive discharge path between metal portion  14 A and a suitable discharging structure such as ground line  22 . 
     In the example of  FIG. 2 , earbud  14  has been provided with resistive electrostatic discharge material  36 . Material  36  may be, for example, a resistive foam or rubber. Conductive particles such as carbon particles or other suitable filler materials may be incorporated into material  36  to ensure that material  36  has a non-zero conductivity and does not act as an insulator. Satisfactory materials  36  will exhibit a sufficiently low resistance to allow current to flow to discharge electrostatic charge buildup. 
     With one suitable arrangement, material  36  may be implemented in the form of a ring-shaped boot member that circumferentially surrounds driver  26 . Boot member  36  may have a conductivity of about 2*10 −5  to 4*10 −7  (Ω-m) −1 . In an earbud having dimensions of about 1 mm to about 1 cm, boot member  36  may have a resistance of about 500 kΩ to 10 MΩ (e.g., less than 30 MΩ, between 30 MΩ and 10 MΩ, between 40 MΩ and 300 kΩ, between 30 MΩ and 1 MΩ, less than 20 MΩ, less than 10 MΩ, less than 1 MΩ, etc.) The resistance of boot member  36  is preferably low enough to bleed off electrostatic charge while being high enough to prevent undesirable leakage currents from developing. Material  36  is somewhat conductive, so whenever electrostatic charge develops on metal structure  14 A, this charge will be discharged through member  36 . 
     As shown in  FIG. 2 , driver  26  may be mounted in driver body  32 . Body structure  32  may be formed from metal. Lines  22  and  24  may pass through holes in metal member  32  and may be electrically connected to driver  26  at terminals  28  and  30 . To ensure that driver body  32  is shorted to ground, conductive epoxy  34 , a spring contact, or other conductor may be connected between ground line  22  and driver body  32 . If a user&#39;s ear or other body part touches earbud housing  14 A and causes housing  14 A to become electrostatically charged, this charge can be discharged by flowing through resistive material  36  to driver body  32  (and thereafter through conductor  34  to ground line  22 ). As shown by segment  48  of dashed line  46 , the opening that was formed through earbud portion  14 B may extend through resistive member  36 . This allows sound from driver  26  to escape from the interior of earbud  14 . 
     If desired, other types of electrostatic discharge path may be formed between housing  14 A and ground line  22 . For example, as shown in  FIG. 2 , one or more discrete resistors such as resistor  50  may be electrically connected between metal housing  14 A and driver body  32 . The ends of resistor  50  may be connected to housing  14 A and body  32  using welds, solder connections, metal springs, or other suitable connections. Earbuds may also be provided with both a distributed discharge path resistance (e.g., material  36 ) and discrete resistors (e.g., resistor  50 ). 
     Electrostatic discharge events may be associated with relatively large voltages. For example, voltages may build up to 5 kV or 10 kV or more. To ensure that resistor  50  is able to withstand these relatively large voltages without damage, resistor  50  may be implemented using a high-voltage design (e.g., a thin-film resistor that is formed from a durable material such as ruthenium oxide and that has a shape that helps prevent voltages from jumping across the resistor housing). More than one resistor  50  may be connected between metal housing  14 A and driver body  32  in parallel if desired. Multiple series-connected resistors  50  may also be used. Arrangements with parallel and series-connected discrete high-voltage resistors may be used instead of distributed resistance material  36  or may be used in the same earbud as material  36 . 
     In the illustrative configuration of  FIG. 2 , resistor  50  is surrounded by material  36  (e.g., a resistive elastomer). This type of configuration may help physically block air discharges around resistor  50  and thereby ensure that resistor  50  is not inadvertently bypassed by an arc through an air gap. If desired, other structures such as non-conductive plastic barrier structures in which resistor  50  is buried may be placed between housing  14 A and driver body  32 . When a barrier such as this is provided in earbud  14  to help prevent inadvertent air discharges, it may be desirable to form resistor  50  from a compact resistor such as a small surface mount technology (SMT) resistor. Larger resistors (e.g., high-voltage resistors in larger packages) may also be sealed within a barrier structure such as a plastic barrier. The barrier in which resistor  50  is mounted may have the shape of material  36  of  FIG. 2  or may have other suitable shapes that force ESD currents to flow through resistor  50  while preventing parallel air discharges. 
     A cross-sectional side view of another illustrative earbud  14  with an internal electrostatic discharge path is shown in  FIG. 3 . As shown in  FIG. 3 , earbud  14  may have metal housing portion  14 A. Metal housing  14 A may include outer metal housing member  54  and inner metal housing member  56 . Plastic housing  58  may be used to route wires  22  and  24  from cable  12  to crossover filter  60  and other circuitry on printed circuit board  62 . Strain-relief portion  66  of housing  58  may receive the end of cable  12  and may, if desired, be formed from an elastomeric substance to allow cable  12  to flex in the vicinity of earbud  14 . 
     Conductive epoxy  34  ( FIG. 2 ) may be placed between board  62  and driver body  32  as described in connection with  FIG. 2 . Earbud member  14 B (e.g., a dielectric earbud member such as an elastomeric earbud member or other ear tip structure) may be connected to metal housing portion  14 A. Channel  46  may be formed within center core portion  52  of elastomeric ear tip member  14 B. Discharge structure  36  may be formed from a non-insulating material (i.e., a slightly conductive material with a non-zero conductivity). Structure  36  may be implemented using a conductive rubber boot structure that surrounds driver body  32 . Channel  46  may be formed through ear bud member  14 B and rubber boot  36 . 
     To prevent particle intrusion into the interior of driver body  32 , which could damage the speakers of driver body  32 , one or more screens may be provided in earbud  14 . These screens may be, for example, polymer screens, metal screens, screens formed from combinations of polymer and metal parts, etc. In the example of  FIG. 3 , threaded cap member  72  may be screwed into mating threads in member  56  and may hold screen  68  in place across channel  46 . An external screen such as screen  70  may also be attached to cap member  72 . Screen  68  may be, for example, a polyester acoustic and particle filter, whereas screen  70  may be a wire mesh that prevents foreign objects from entering channel  46 . 
     If desired, earbud structure  14 B may be used to discharge electrostatic charge (e.g., to ground line  22 ). An earbud structure of this type may be formed from a conductive (non-insulating) material and may exhibit a resistance of about 10-30 MΩ. A conductive (resistive) earbud structure of this type may be used in the same earbud  14  as conductive rubber boot  36  or may be used in an earbud without any other internal electrostatic discharge paths. Conductive (resistive) discharge paths may also be formed in cable  12  (e.g., by forming some or all of the jacket in cable  12  from a material that has a non-zero conductivity and by shorting the jacket to ground  22  or other suitable discharge path). 
     A cross-sectional view of earbud  14  in the vicinity of printed circuit board  62  is shown in  FIG. 4 . As shown in  FIG. 4 , earbud  14  may have a printed circuit board  62  to which electrical circuits such as circuits  60  may be mounted. Circuits  60  may include crossover components, amplifier components, and other suitable audio circuits. Audio signals may be received using positive signal wire  24  and ground wire  22 . 
     There may be two or more speaker driver modules in earbud  14 . In the example of  FIG. 4 , earbud  14  includes low frequency driver  26 L (a “woofer”) and high frequency driver  26 H (a “tweeter”). Drivers such as drivers  26 L and  26 H may be provided in one or more separate housings. For example, driver  26 L may be provided in metal driver housing  32 L and driver  26 H may be provided in metal driver housing  32 H. To ensure satisfactory electrostatic discharge, housings  32 L and  32 H may be electrically connected (e.g., using solder  74 ). Conductive epoxy, a conductive spring, or other suitable conductive structure  34  may be used to electrically connect driver housing  32 H to ground  22  (e.g., to ground trace  76  on board  62 , which is connected to ground  22 ). 
     Arrangements of the type shown in  FIG. 4  work well with existing driver modules, because conductive epoxy  34  can be used to short cases  26 L and  26 H to ground trace  76  without introducing high temperatures that might damage the headphone speakers. If desired, however, higher temperature processes may be used. As shown in  FIG. 5 , for example, driver housing  26  may have a protrusion such as shorting member  320 . Housing  26  may be formed from metal and shorting member  320  may be formed from a portion of the same metal. Shorting member  320  may be inserted in a hole in printed circuit board  62 . Solder  78  may be used to form a solder connection between shorting member  320  and ground trace  76 . This shorts driver housing  26  to ground line  22  (see  FIG. 4 ), which is electrically connected to ground trace  76 . 
     If desired, other structures may be used to receive electrostatic discharge current through boot member  36 . For example, a metal screen (e.g., a stainless steel mesh such as screen  70  of  FIG. 3 ) may be shorted to ground  22  (e.g., using a wire, using a connection to a trace on a board or other metal structure, etc.). Boot member  36  may be electrically connected to screen  70 , so that boot member  36  forms an electrostatic discharge path through boot member  36  into screen  70  and ground  22 . 
     The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention.

Metadata:
Filing Date: 20090708
Publication Date: 20130423
Grant Date: 20130423
Priority Date: 20090708
Inventors: RABU STANLEY
LO IDA
TISCARENO VICTOR
LIM CRAIG
CHUNDRU RAMACHANDRAN
STEINFELD ROBERT
STIEHL KURT
Assignee: APPLE INC
CPC Classifications: [{"code": "H04R2201/105", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/1016", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/1075", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/26", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/26", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/1075", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/1091", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R1/1033", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R1/1033", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 43427497