PATENT DOCUMENT

Publication Number: US-9807919-B2
Application Number: US-201414167625-A
Country: US
Kind Code: B2

Title: Electronic devices having electrostatic discharge paths

Abstract:
An electronic device may have a display and other electrical components that are sensitive to electrostatic charge. A button may pass through an opening in a layer of the display. A metal trim may surround the button. The housing may have an opening with a clear lens surrounded by a metal trim. To prevent damage from electrostatic discharge, an electrostatic discharge path may be formed in the device that includes a metal trim surrounding a component such as a button member or camera lens, metal traces on the inner surface of a display layer or a housing, a grounded metal housing structure, and a spring or other conductive structure that couples the metal traces to the grounded metal housing structure. Displays may be provided with electrostatic discharge paths that route electrostatic charge to grounded metal housing structures.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a housing; 
 a display mounted in the housing, wherein the display includes an outermost display layer, wherein the display has an active area in which images are displayed, wherein the display has an inactive area that surrounds the active area, wherein the outermost display layer has first and second surfaces, and wherein the outermost display layer has an opening that extends from the first surface to the second surface; 
 a grounded metal structure in the housing; 
 an electrostatic discharge path that includes a conductive trace on the outermost display layer, that includes the grounded metal structure, and that includes a conductive structure coupled between the conductive trace and the grounded metal structure that shorts the conductive trace to the grounded metal structure; and 
 a metal trim structure formed in the opening in the outermost display layer, wherein the electrostatic discharge path also includes the metal trim structure, and wherein the conductive structure shorts the metal trim structure to the grounded metal structure. 
 
     
     
       2. The electronic device defined in  claim 1 , wherein the conductive structure comprises a metal spring that forms part of the electrostatic discharge path. 
     
     
       3. The electronic device defined in  claim 2 , wherein the grounded metal structure comprises a sheet metal member. 
     
     
       4. The electronic device defined in  claim 3 , further comprising a button member, wherein the metal trim structure surrounds the button member. 
     
     
       5. The electronic device defined in  claim 4 , wherein the outermost display layer comprises a display cover layer and wherein the button member and metal trim structure move within the opening. 
     
     
       6. The electronic device defined in  claim 1 , wherein the outermost display layer comprises a glass display cover layer and wherein the conductive trace comprises a metal trace on the glass display cover layer. 
     
     
       7. The electronic device defined in  claim 1 , further comprising a button member, wherein the button member and metal trim structure move within the opening. 
     
     
       8. The electronic device defined in  claim 7 , further comprising a sensor mounted to the button member and an opaque masking layer on an inner surface of the outermost display layer in the inactive area, wherein the conductive trace comprises a metal trace on the opaque masking layer. 
     
     
       9. The electronic device defined in  claim 8 , wherein a portion of the metal trace forms a ring that surrounds the button member. 
     
     
       10. The electronic device defined in  claim 1 , wherein the active area is a rectangular active area and wherein the electrostatic discharge path has a rectangular ring shape that surrounds the rectangular active area. 
     
     
       11. The electronic device defined in  claim 1 , wherein the conductive trace on the outermost display layer surrounds the active area. 
     
     
       12. The electronic device defined in  claim 1 , wherein the metal trim structure directly contacts the conductive trace. 
     
     
       13. The electronic device defined in  claim 1 , wherein the outermost display layer comprises a display cover layer, and wherein the active area in which the images are displayed is visible through the display cover layer. 
     
     
       14. The electronic device defined in  claim 1 , further comprising a coating formed on the metal trim structure, wherein the coating is formed from metal, and wherein the coating directly contacts the conductive trace. 
     
     
       15. The electronic device defined in  claim 1 , wherein the conductive trace on the outermost display layer forms a ring that surrounds the active area, wherein the conductive trace has a contact region that protrudes outwardly from the ring, and wherein the conductive structure contacts the contact region to short the conductive trace to the grounded metal structure. 
     
     
       16. The electronic device defined in  claim 1 , wherein at least a portion of the metal trim structure is interposed between the first and second surfaces of the outermost display layer. 
     
     
       17. An electronic device, comprising:
 a housing; 
 a display mounted in the housing, wherein the display includes an outermost display layer, wherein the display has an active area in which images are displayed, wherein the display has an inactive area that surrounds the active area, wherein the outermost display layer has first and second surfaces, and wherein the outermost display layer has an opening that extends from the first surface to the second surface; 
 a grounded metal structure in the housing; 
 an electrostatic discharge path that includes a conductive trace on the outermost display layer, that includes the grounded metal structure, and that includes a conductive structure coupled between the conductive trace and the grounded metal structure that shorts the conductive trace to the grounded metal structure; 
 a metal trim structure in the opening in the outermost display layer, wherein the electrostatic discharge path also includes the metal trim structure, and wherein the conductive structure shorts the metal trim structure to the grounded metal structure; and 
 a clear lens in the metal trim structure. 
 
     
     
       18. The electronic device defined in  claim 17 , wherein the electrostatic discharge path includes a metal trace on the housing. 
     
     
       19. The electronic device defined in  claim 18 , further comprising a camera that receives light through the clear lens in the metal trim structure. 
     
     
       20. The electronic device defined in  claim 19 , wherein the active area in which the images are displayed is visible through the outermost display layer.

Description:
BACKGROUND 
     This relates generally to electronic devices, and, more particularly, to structures for discharging electrostatic charge in electronic devices. 
     Electronic devices include components such as sensors, integrated circuits, and other electrical components. Circuitry in these components can be sensitive to electrostatic charge. Electrostatic discharge events may arise when a user touches a sensitive component or touches a portion of an electronic device housing in which a sensitive component is mounted. If care is not taken, sensitive circuitry can be damaged by electrostatic charge during electrostatic discharge events. 
     It would therefore be desirable to be able to provide an improved arrangement for protecting sensitive electrical components in an electronic device from damage during electrostatic discharge events. 
     SUMMARY 
     An electronic device may have electrical components that are sensitive to electrostatic charge. For example, an electronic device may have a button with a sensor, a camera, and a display that are sensitive to electrostatic charge. 
     The display and other electrical components may be mounted in a housing. A button may pass through an opening in an outermost layer of the display. A metal trim may surround the button. The housing may have an opening with a clear camera lens surrounded by a metal trim. 
     To prevent damage from electrostatic discharge, an electrostatic discharge path may be formed in the device. The electrostatic discharge path may include a metal trim surrounding a component such as a button member or camera lens, a patterned metal trace on the inner surface of the outermost display layer or the housing, a grounded metal housing structure, and a spring or other conductive structure that couples the metal trace to the grounded metal housing structure and thereby shorts the metal trim to ground. 
     Displays may be provided with electrostatic discharge paths that route electrostatic charge to the grounded metal housing structures. For example, a metal trace with the shape of a rectangular ring may surround a rectangular active area in a display. The metal trace may be formed on the innermost surface of the outermost display layer in the display. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device such as a handheld computing device of the type that may be provided with an electrostatic discharge protection structure in accordance with an embodiment. 
         FIG. 2  is a schematic diagram of an illustrative electronic device in accordance with an embodiment. 
         FIG. 3  is a cross-sectional side view of an electronic device having electrical components and an electrostatic discharge protection structure for protecting the electronic components from damage during electrostatic discharge events in accordance with an embodiment. 
         FIG. 4  is a perspective view of an illustrative electronic device with an electrostatic discharge path formed on the underside of a display layer in accordance with an embodiment. 
         FIG. 5  is a cross-sectional side view of an electronic device having a button with a metal trim and having a conductive layer on the underside of a display layer that forms part of an electrostatic discharge path in accordance with an embodiment. 
         FIG. 6  is a cross-sectional side view of a portion of an electronic device in which an electronic component is mounted under a housing or display layer with a lens surrounded by a metal trim and in which an electrostatic discharge path is formed in accordance with an embodiment. 
         FIG. 7  is a top view of a display cover layer having a ring of conductive material that surrounds an active area of a display and serves as an electrostatic discharge path in accordance with an embodiment. 
         FIG. 8  is a cross-sectional side view of a portion of an electronic device in which an electrostatic discharge path on the underside of a display cover layer has been shorted to a ground formed from a metal housing structure in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices may be provided with electrical components such as sensors, integrated circuits, light-emitting didoes and other components that emit light, light detectors, cameras, buttons, speakers, microphones, vibrators, tone generators, communications circuitry, and other electrical components. The circuitry of these components may be sensitive to damage from electrostatic charge generated during electrostatic discharge events. For example, an electrical component may be damaged when a user touches an electronic device and discharges static charge from the user&#39;s body into an ungrounded portion of the electronic device. 
     Damage from electrostatic discharge can be avoided by providing conductive electrostatic discharge paths within electronic devices. With this type of arrangement, electrostatic charge from the body of a user may flow safely to ground without damaging sensitive circuitry. In devices with displays, part of an electrostatic discharge path may be provided by conductive traces on part of the display. Electrostatic discharge paths may also be formed on the inner surface of an electronic device housing. 
       FIG. 1  is a perspective view of an illustrative electronic device of the type that may be provided with an electrostatic discharge path to prevent sensitive electrical components from being damaged during an electrostatic discharge event. An electronic device such as electronic device  10  of  FIG. 1  may be a computing device such as a laptop computer, a computer monitor containing an embedded computer, a tablet computer, a cellular telephone, a media player, or other handheld or portable electronic device, a smaller device such as a wrist-watch device, a pendant device, a headphone or earpiece device, or other wearable or miniature device, a television, a computer display that does not contain an embedded computer, a gaming device, a navigation device, an embedded system such as a system in which electronic equipment with a display is mounted in a kiosk or automobile, equipment that implements the functionality of two or more of these devices, or other electronic equipment. In the illustrative configuration of  FIG. 1 , device  10  is a portable device such as a cellular telephone, media player, tablet computer, or other portable computing device. Other configurations may be used for device  10  if desired. The example of  FIG. 1  is merely illustrative. 
     Device  10  may have one or more displays such as display  14  mounted in housing structures such as housing  12 . Housing  12  of device  10 , which is sometimes referred to as a case, may be formed of materials such as plastic, glass, ceramics, carbon-fiber composites and other fiber-based composites, metal (e.g., machined aluminum, stainless steel, or other metals), other materials, or a combination of these materials. Device  10  may be formed using a unibody construction in which most or all of housing  12  is formed from a single structural element (e.g., a piece of machined metal or a piece of molded plastic) or may be formed from multiple housing structures (e.g., outer housing structures that have been mounted to internal frame elements or other internal housing structures). 
     Display  14  may be a touch sensitive display that includes a touch sensor or may be insensitive to touch. Touch sensors for display  14  may be formed from an array of capacitive touch sensor electrodes, a resistive touch array, touch sensor structures based on acoustic touch, optical touch, or force-based touch technologies, or other suitable touch sensor components. 
     Display  14  for device  10  includes display pixels formed from liquid crystal display (LCD) components or other suitable display pixel structures such as organic light-emitting diode display pixels, electrophoretic display pixels, plasma display pixels, etc. The display pixels may be arranged in an array having numerous rows and columns to form rectangular active area AA of  FIG. 1 . Rectangular active area AA may be located in the center of device  10  and may be surrounded by inactive border regions such as inactive area IA. Inactive area IA may have a rectangular ring shape of the type shown in  FIG. 1  or may extend only along a pair of the edges of device  10  (e.g., along the upper and lower edges of device  10  in a configuration in which the left and right edges of device  10  are borderless). Other inactive area shapes may be used, if desired. 
     A display cover layer may cover the surface of display  14  or a display layer such as a color filter layer (e.g., a layer formed from a clear substrate covered with patterned color filter elements) or other portion of a display may be used as the outermost (or nearly outermost) layer in display  14 . In this type of configuration, the color filter layer or other outermost layer may sometimes be referred to as a display cover layer. The outermost display layer may be formed from a transparent glass sheet, a clear plastic layer, or other transparent member. 
     To hide internal components from view, the underside of the outermost display layer or other display layer surface in inactive area IA may be coated with an opaque masking layer such as a layer of ink (e.g., black or white ink). If desired, openings may be formed in the outermost layer of display  14  (e.g., in inactive area IA) to accommodate components such as button  16 . An opening for a speaker port such as speaker port  18  or other openings may also be formed in the outermost layer of display  14 . Camera windows such as camera window  20  may be formed in inactive area IA of display  14 , on the edges of housing  12 , or on the rear of housing  12  (as examples). In general, any suitable electrical components (e.g., buttons, connector ports, audio ports, sensors, other components, etc.) may be accommodated using openings in housing  12  and/or display  14 . The example of  FIG. 1  is merely illustrative. 
     A schematic diagram of an illustrative configuration that may be used for electronic device  10  is shown in  FIG. 2 . As shown in  FIG. 2 , electronic device  10  may include control circuitry  22 . Control circuitry  22  may include storage and processing circuitry for controlling the operation of device  10 . Control circuitry  22  may, for example, include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Control circuitry  22  may include processing circuitry based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio codec chips, application specific integrated circuits, etc. 
     Input-output devices  24  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Input-output devices  24  may also include input-output components with which a user can control the operation of device  10 . A user may, for example, supply commands through input-output devices  24  and may receive status information and other output from device  10  using the output resources of input-output devices  24 . 
     Input-output devices  24  may include sensors and status indicators such as an ambient light sensor, a proximity sensor, a temperature sensor, a pressure sensor, a magnetic sensor, an accelerometer, a touch sensor, a fingerprint sensor, and light-emitting diodes and other components for gathering information about the environment in which device  10  is operating and providing information to a user of device  10  about the status of device  10 . Audio components in devices  24  may include speakers and tone generators for presenting sound to a user of device  10  and microphones for gathering user audio input. Devices  24  may include one or more displays. Displays may be used to present images for a user such as text, video, and still images. Sensors in devices  24  may include a touch sensor array that is formed as one of the layers in display  14 . During operation, user input may be gathered using buttons and other input-output components in devices  24  such as touch pad sensors, buttons, joysticks, click wheels, scrolling wheels, touch sensors such as a touch sensor array in a touch screen display or a touch pad, key pads, keyboards, vibrators, cameras, and other input-output components. The input-output devices of device  10  may include wired and wireless communications circuitry (e.g., circuitry to support digital data communications, a radio-frequency transceiver and antennas for supporting wireless communications, etc.). 
     A cross-sectional side view of an illustrative electronic device such as electronic device  10  of  FIG. 1  taken along line  70  and viewed in direction  72  is shown in  FIG. 3 . As shown in  FIG. 3 , display  14  may be mounted within housing  12 . Display  13  may include display layers  28 L and an outermost display layer such as display cover layer  30 . Display layers  28 L may include organic light-emitting diode structures, liquid crystal display structures, or other display structures. As an example, in a liquid crystal display configuration, display layers  28 L may include upper and lower polarizer layers, a color filter layer and thin-film transistor layer between the polarizer layers, and a layer of liquid crystal material between the color filter layer and the thin-film transistor layer. 
     Display layers  28 L, which may sometimes be referred to as forming a display, display module, or display structure, include an array of display pixels. The display pixels overlap rectangular active area AA and are used in displaying images for a user of device  10  in active area AA. Inactive area IA does not contain display pixels and does not produce images for a user. To hide internal device structures from view, the inner surface (i.e., the underside) of display cover layer  30  may be coated with an opaque masking layer such as opaque masking layer  32  in inactive area IA. Opaque masking layer  32  may be formed from a layer of ink (e.g., black ink, white ink, ink with other colors) or other opaque material. 
     Device  10  may include a button such as button  16 . A user may press button  16  (e.g., using finger  36  or other external object). Button  16  may have a movable button member that moves within opening  34  in display cover layer  30 . 
     Device  10  may also contain other electrical components such as electrical components  38  (e.g., input output devices  24  and control circuitry  22  of  FIG. 2 ). Electrical components  38  may be interconnected using wires, cables, flexible printed circuit cables, interconnects on printed circuit board, and other conductive paths. As shown in  FIG. 3 , for example, electrical components  38  may be mounted on a substrate such as printed circuit  40 . Printed circuit  40  may be a rigid printed circuit board (e.g., a printed circuit board formed from fiberglass-filled epoxy or other rigid printed circuit board material) or may be a flexible printed circuit (e.g., a flex circuit formed from a layer of polyimide or a sheet of other flexible polymer). Metal traces on printed circuit  40  may form interconnects that interconnect the circuitry of components  38 . 
     Electrical components  38  may include integrated circuits, sensors, switches, cameras and other light-based components, speakers, microphones, and other audio components, communications circuitry, processing circuitry, storage circuits, etc. Electrical components  38  may have conductive contacts (terminals) that can be electrically connected to mating contact pads on printed circuits such as printed circuit  40 . The contact pads on the printed circuit may be formed from patterned metal traces. Conductive adhesive, solder, or other conductive connections may be used in mounting the electrical components to the contacts on the printed circuit. 
     External objects such as user&#39;s finger  36  may carry electrostatic charge. When a user&#39;s finger touches a part of device  10  such as button  16  or other portion of device  10 , sensitive circuitry in device  10  may potentially be exposed to the electrostatic charge. To prevent damage to sensitive electrical components in device  10  such as button  16  and other electrical components  38 , device  10  can be provided with electrostatic discharge paths. As an example, conductive traces can be formed on substrates such as display cover layer  30 . A conductive trace may be formed from a metal, a conductive material such as indium tin oxide, or other conductive material. A conductive path that is formed at least partly from a conductive trace on display cover layer  30  (e.g., on the inner surface of display cover layer  30  in inactive area IA) may be used to safely discharge electrostatic charge from a user&#39;s finger or other source to ground. 
       FIG. 4  is a perspective view of a portion of electronic device  10  in the vicinity of button  16 . In the illustrative configuration of  FIG. 4 , button  16  has a dielectric button member such as button member  16 M and a metal trim member such as metal trim  16 R. Button  16  may, in general, have any suitable footprint (e.g., a rectangular outline, a shape with curved and straight sides, etc.). The arrangement of  FIG. 4  in which button member  16 M has a circular outline and in which metal trim  16 R has the shape of a circular ring that surrounds button member  16 M is merely illustrative. 
     When a user&#39;s finger presses against button  16  during use of device  10 , electrostatic charge can be deposited on metal structures such as metal trim  16 R. To protect button  16  and other sensitive circuitry in device  10  from damage due to the electrostatic charge, an electrostatic discharge path may be formed in device  10 . The electrostatic discharge path may include metal traces, metal spring structures, and other conductive path structures that ground metal trim  16 R to a source of ground potential. With the illustrative arrangement of  FIG. 4 , the underside of display  14  (i.e., the underside of display cover layer  30  in inactive area IA of display  14 ) has been provided with a patterned conductive layer such as layer  46  (e.g., a metal trace formed from a patterned metal layer deposited using physical vapor deposition, a metal trace formed from metal paint such as pad-printed or screen-printed metal paint, or other conductive trace). 
     Layer  46  may have a portion with a ring shape that surrounds button  16  and a portion that forms a contact such as contact  48 . If desired, layer  46  may be formed from a metal trace with other shapes (e.g., elongated lines, rings, etc.). The example of  FIG. 4  is illustrative. 
     As shown in  FIG. 4 , portion  48  of conductive layer may be coupled to a spring or other structure that is shorted to ground. With this arrangement, metal ring  16 R is shorted to conductive layer  46  on display  14  and a spring or other conductive structure in device  10  couples layer  46  to ground. The ground may be associated with a metal portion of device  10  such as a metal housing midplate (i.e., a sheet metal member or other planar metal member) that serves as an internal support structure for the housing of device  10 , may be associated with metal housing walls, or may be associated with other grounded metal housing structures. 
     During operation, a user&#39;s finger is used to press against button  16  to operate button  16 . Part of the user&#39;s finger bears against dielectric button member  16 M and causes button  16  to press against internal button structures such as a dome switch or other electrical switching structures. Another part of the user&#39;s finger touches metal trim  16 R. Upon contact between the user&#39;s finger and metal trim  16 R, electrostatic charge from the user&#39;s finger is safely discharged to ground through the electrostatic discharge path formed from trim  16 R, metal trace  46 , the spring contacted to portion  48  of trace  46 , and other conductive electrostatic discharge path structures in device  10 . 
       FIG. 5  is a cross-sectional side view of device  10  of  FIG. 4  taken along line  74  and viewed in direction  76  of  FIG. 4 . As shown in  FIG. 5 , metal structure  52  is grounded (see, e.g., ground  56 ). Grounded metal structure  52  may be a metal trace on a printed circuit, may be a portion of a housing wall, or may be an internal housing structure. As an example, metal structure  52  may be a planar internal housing structure such as a piece of stamped sheet metal or other metal plate. The metal plate may be formed within the middle of device  10 , may be welded to metal housing walls, and may sometimes be referred to as a housing reinforcement plate or housing midplate. 
     During operation of device  10 , electrostatic charge can be safely discharged to ground (i.e., to grounded metal structures such as structure  52 ) via an electrostatic discharge path. The electrostatic discharge path in the illustrative arrangement of  FIG. 5  includes metal trim  16 R, a patterned conductive layer such as metal trace  46  on display cover layer  30 , and metal spring  50 . If desired, other metal structures may be interposed in the electrostatic discharge path (e.g., wires, metal housing structures, metal traces on one or more substrates in device  10  such as printed circuit board substrates, etc.). Metal structures such as spring  50  may also be implemented using spring-loaded pins, conductive foam, a conductive fabric gasket, or other conductive structures. The configuration of  FIG. 5  is merely illustrative. 
     As shown in  FIG. 5 , button  16  may have metal trim  16 R. Metal trim  16 R may have a ring shape and may be formed around the outer edge of a circular button member such as button member  16 M. Button member  16 M may be formed from a dielectric such as plastic, glass, ceramic, other dielectric materials, or two or more dielectric materials. Display cover layer may have opposing inner (lower) and outer (upper) surfaces such as inner surface  82  and outer surface  80 . In inactive area IA of display  14 , display cover layer  30  may be provided with an opaque masking layer such as opaque masking layer  42  on inner surface  82 . Conductive trace  46  may be patterned on opaque masking layer  42 , so that conductive trace  46  is not visible to user  84  viewing device  10  in direction  86 . 
     Button  16  may have a switch such as dome switch  60 . Dome switch  60  may have open and closed states. As an example, dome switch  60  may be open when button member  16 M is not being depressed by a user and may be closed when button member  16 M has been moved downwards in direction  86  when pressed by a user. Dome switch  60  may bear against a structure such as printed circuit  40  or other structure within device  10 . Dome switch  60  may be soldered to a substrate such as flexible printed circuit  88 , which is connected to printed circuit  40  by connector  58 . Switch  60  may bias member  16 M upwards when not in use and may be compressed downwards when button  16 M is moved downwards by a user. 
     If desired, button  16  may contain additional circuitry such as sensor circuitry  62 . Sensor circuitry  62  may be mounted to the underside of button member  16 M and may be electrically connected to metal traces in flexible printed circuit  88 . Sensor circuitry  62  may be a fingerprint sensor, a touch sensor, a strain gauge sensor, a force sensor, a proximity sensor, or other suitable sensor. 
     Sensor  62  and other circuitry associated with button  16  such as dome switch  60  may be sensitive to electrostatic charge. To prevent damage to sensor  62 , dome switch  60 , and other electrical components  38  in device  10 , an electrostatic discharge path is provided between metal trim  16 R and grounded structure  52 . When button  16  is in its undepressed state, trim member  16 R presses against conductive trace  46  and is shorted to conductive trace  46 . To help reduce contact resistance between trim member  16 R and conductive trace  46 , trim member  16 R and/or conductive trace  46  can be provided with a coating such as illustrative coating  64 . Trace  46  may be formed from a metal such as silver, nickel, zinc, aluminum, or copper (as examples) or may be formed form a conductive material such as indium tin oxide or other conductive material. Coating  64  may be, for example, a layer of gold or other metal that has a low resistance (i.e., a high conductivity) and does not readily form a native oxide. Trim  16 R may be formed from a metal such as stainless steel or other metal. 
     Spring  50  or other conductive biasing structure for contacting trace  46  may be formed from a conductive material such as metal. Spring  50  may be coupled to metal structure  52 . As shown in  FIG. 5 , for example, spring  50  may be attached to metal structure  52  using conductive connections  54 . Conductive connections  54  may be welds, solder joints, conductive adhesive connections, screws or other fasteners, or other suitable electrical and/or mechanical coupling structures. Spring  50  may form an electrical contact with conductive trace  46  at contact point  48 . This forms an electrostatic discharge path from trim  16 R, through layers  64  and  46 , and through spring  50  to metal structure  52 . 
     Initially, when button  16  is not depressed, trim  16 R is shorted to conductive layer  46 . When a user desires to press button  16 , the user&#39;s finger will contact metal trim  16 R. As soon as electrical contact is established between the user&#39;s finger and metal trim  16 R (i.e., before button  16  has actually been moved in a downwards direction), electrostatic charge from the user&#39;s finger will flow through the electrostatic discharge path made up of trim  16 R, trace  46 , and spring  50  to grounded metal structure  52  or other ground. As the user continues to press against button  16 , button member  16 M will move downwards in direction  86 . This will disconnect trim  16 R from layer  46  temporarily, but because the electrostatic charge from the user&#39;s finger has already been discharged through the electrostatic discharge path that was initially present, sensitive circuitry in device  10  such as sensor  62 , switch  60 , and electrical components  38  will be protected from electrostatic discharge damage. 
     In the example of  FIG. 5 , sensitive circuitry associated with a button such as button-mounted sensor  62  is being protected from electrostatic charge. If desired, other types of circuitry in device  10  may be protected using an electrostatic discharge path that is formed using conductive layer  46 . Consider, as an example, the arrangement of  FIG. 6 . As shown in  FIG. 6 , a sensitive electrical component such as camera  92  (e.g., a digital image sensor) may be mounted under camera window  20 . Camera window  20  may include a clear window member such as transparent member  90 M. Member  90 M, which may sometimes be referred to as a lens or window, may be a transparent disk formed from glass or plastic (as an example). Window member  90 M may be surrounded by a metal structure such as metal trim  90 T. Window  20  may be formed from an opening in layer  96 . Layer  96  may be opaque or clear. In configurations in which layer  96  is clear, the underside of layer  96  may, if desired, be covered with an opaque masking layer such as layer  42 . Layer  96  may be a display layer (e.g., display cover layer  30 ), may be a wall in housing  12  (e.g., a plastic housing wall or other housing structure), or other layer in device  10 . 
     Camera  92  may receive light associated with images through window member  90 M. Camera  92  may digitize the incoming light and may provide corresponding digital image data to processing circuitry  22  via signal paths in flexible printed circuit  94 . To protect sensitive circuitry such as camera  92  from electrostatic charge, a conductive electrostatic discharge path to ground may be formed in device  10 . As shown in  FIG. 6 , for example, grounded metal structures  52  may be connected to spring  50  or other conductive biasing structure using connections  54  (e.g., solder, welds, conductive adhesive, fasteners, etc.). Spring  50  may bear against patterned conductive trace  46  at contact point  48 . With this arrangement, a user&#39;s finger that touches metal trim  90 T is shorted to ground (i.e., grounded structures  52 ) via an electrostatic discharge path formed using trim  90 T, conductive trace  46 , spring  50  (or other conductive path structure), and metal structures  52  (which form ground in this example). 
     If desired, conductive layer  46  may be patterned to form an electrostatic discharge path that surrounds a display. As shown in the top view of display  14  of  FIG. 7 , for example, device  10  may have a display with a rectangular active area AA (defined by border  100 ). Active area AA may be surrounded by a rectangular ring-shaped inactive area IA. Display layers  28 L ( FIG. 3 ) may be formed in active area AA. To ensure that electrostatic charge does not damage the circuitry of display layers  28 L or other sensitive circuitry in device  10 , display  14  may be provided with an electrostatic discharge path. The electrostatic discharge path may include a patterned conductive layer such as patterned conductive layer  46  on the underside of display cover layer  30 . Conductive layer  46  may form a ring that surrounds active area AA. Conductive layer  46  may, if desired, have contact regions formed from protrusions  46 P that protrude outwardly from rectangular ring-shaped conductive layer  46 . Springs or other conductive structures may contact one or more of protrusions  46 P to short conductive layer  46  to ground (see, e.g., spring contact point  48 ). 
       FIG. 8  is a cross-sectional side view of the structures of  FIG. 7  taken along line  96  and viewed in direction  98 . As shown in  FIG. 8 , inner surface  82  of display cover layer  30  may be coated with opaque masking layer  42  in inactive area IA to hide internal components in device  10  from view. Conductive layer  46  may be patterned on the inner surface of opaque masking layer  42 . Metal spring  50  or other conductive structure may contact layer  46  at a location such as contact location  48 , thereby shorting conductive layer  46  to spring  50 . Spring  50  is connected to metal structure  52 , which is grounded. Connections  54  such as welds, solder connections, connections formed from conductive adhesive, and/or connections formed using fasteners may be used to connect spring  50  to metal structure  52 . If desired, metal structures such as metal structure  52  of  FIG. 8  and metal structure  52  of  FIGS. 5 and 6  may be welded or otherwise coupled to housing  12  (e.g., a metal housing) to provide further grounding. The configuration of  FIG. 8  forms an electrostatic discharge path to ground that includes conductive trace  46 , spring  50 , metal structure  52  and/or metal housing  12 , thereby helping to discharge electrostatic charge to ground that is imparted to display  14  in the vicinity of conductive layer  46  from a user&#39;s finger or other external object in contact with device  10 . 
     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: 20140129
Publication Date: 20171031
Grant Date: 20171031
Priority Date: 20140129
Inventors: KWONG KELVIN
Assignee: APPLE INC
CPC Classifications: [{"code": "H05K9/0067", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K9/0067", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 53680470