PATENT DOCUMENT

Publication Number: US-9928762-B2
Application Number: US-201313770527-A
Country: US
Kind Code: B2

Title: Electronic devices with flexible circuit light shields

Abstract:
Electronic devices may include displays. A display may include backlight structures that generate light and display layers that generate images using the generated light. An electronic device may include an opaque flexible printed circuit that is wrapped around one or more edges of the backlight structures. The opaque flexible printed circuit may prevent light from the backlight structures from reaching other electronic components or escaping from the device. The opaque flexible printed circuit may include signal lines that communicate signals between a printed circuit board and the display. The opaque flexible printed circuit may be a layer of the printed circuit board that extends from an edge of the printed circuit board. The printed circuit board may include an additional flexible extended printed circuit layer that wraps around a surface of the printed circuit board and forms a portion of a conductive shield over that surface.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a display having backlight structures and display layers, wherein the backlight structures are configured to generate light that passes through the display layers during operation of the display; and 
 a printed circuit board having a plurality of printed circuit layers, wherein the plurality of printed circuit layers include a plurality of rigid printed circuit layers, wherein one of the printed circuit layers is an opaque flexible printed circuit layer that is formed separately from the plurality of rigid printed circuit layers, wherein a first portion of the opaque flexible printed circuit layer extends from an edge of the plurality of rigid printed circuit board layers around an edge of the backlight structures, the first portion of the opaque flexible printed circuit layer has an end that is attached to the display layers, a second portion of the opaque flexible printed circuit layer wraps around and surrounds at least one of the plurality of rigid printed circuit layers, and the second portion of the opaque flexible printed circuit layer has an end that is attached to the first portion. 
 
     
     
       2. The electronic device defined in  claim 1 , further comprising an electronic component, wherein the opaque flexible printed circuit layer prevents additional light that has been generated by the backlight structures from reaching the electronic component. 
     
     
       3. The electronic device defined in  claim 2  wherein the display layers include a thin-film transistor layer and wherein the end of the first portion of the opaque flexible printed circuit layer is attached to the thin-film transistor layer. 
     
     
       4. The electronic device defined in  claim 3  wherein the opaque flexible printed circuit layer includes metal traces that convey signals from the printed circuit board to the thin-film transistor layer. 
     
     
       5. The electronic device defined in  claim 3  wherein the display further comprises a touch-sensitive layer. 
     
     
       6. The electronic device defined in  claim 5  wherein the opaque flexible printed circuit layer is attached to the thin-film transistor layer in a gap between the thin-film transistor layer and the touch-sensitive layer. 
     
     
       7. The electronic device defined in  claim 6  wherein the gap has a thickness of less than 0.5 mm. 
     
     
       8. The electronic device defined in  claim 2  wherein the electronic component comprises an antenna. 
     
     
       9. The electronic device defined in  claim 1  wherein the backlight structures include a metal chassis and wherein the printed circuit board is attached to the metal chassis. 
     
     
       10. The electronic device defined in  claim 1  wherein the plurality of printed circuit board layers further comprises an additional flexible printed circuit layer that extends from an additional edge of the plurality of rigid printed circuit board layers and wherein the additional flexible printed circuit layer has an end that is attached to the backlight structures. 
     
     
       11. The electronic device defined in  claim 10  wherein the backlight structures include a metal chassis and wherein the end of the additional flexible printed circuit layer is conductively coupled to the metal chassis. 
     
     
       12. An electronic device, comprising:
 a printed circuit board having a plurality of rigid printed circuit board layers; 
 an electronic component mounted on a first rigid printed circuit board layer of the plurality of rigid printed circuit board layers; 
 a flexible printed circuit formed separately from the plurality of rigid printed circuit board layers, wherein the flexible printed circuit has a first portion that is interposed between two rigid printed circuit board layers of the plurality of rigid printed circuit board layers, and wherein the flexible printed circuit has a second portion that is wrapped completely around the electronic component and at least one of the rigid printed circuit board layers to form at least a portion of a conductive shield that blocks electromagnetic radiation that is emitted from the electronic component; and 
 conductive standoff structures on the first rigid printed circuit board layer, wherein the conductive standoff structures and the second portion of the flexible printed circuit form the conductive shield. 
 
     
     
       13. The electronic device defined in  claim 12 , wherein the electronic component and the first rigid printed circuit board layer are interposed between the first portion of the flexible printed circuit and the second portion of the flexible printed circuit. 
     
     
       14. The electronic device defined in  claim 13 , wherein the second portion of the flexible printed circuit is conductively coupled to the conductive standoff structures. 
     
     
       15. The electronic device defined in  claim 12 , further comprising:
 a display having backlight structures and display layers. 
 
     
     
       16. The electronic device defined in  claim 15 , further comprising:
 an opaque flexible printed circuit that extends from an additional edge of the plurality of rigid printed circuit board layers around an edge of the backlight structures, wherein the opaque flexible printed circuit has an end that is attached to the display layers. 
 
     
     
       17. The electronic device defined in  claim 16 , wherein the flexible printed circuit is conductively coupled to the opaque flexible printed circuit. 
     
     
       18. An electronic device, comprising:
 a display having backlight structures and display layers, wherein the backlight structures are configured to generate light for the display; 
 a printed circuit board, wherein the backlight structures are interposed between the printed circuit board and the display layers; and 
 first, second, and third flexible printed circuits attached to the printed circuit board, wherein the first flexible printed circuit has an end that is attached to the display layers, the second flexible printed circuit has an end that is attached to the backlight structures, the third flexible printed circuit has a portion that passes over a surface of the printed circuit board and an end that is attached to the first flexible printed circuit, and the portion of the flexible printed circuit that passes over the surface of the printed circuit board completely covers the printed circuit board. 
 
     
     
       19. The electronic device defined in  claim 18  wherein the first flexible printed circuit comprises a continuous sheet of flexible printed circuitry that is wrapped around an edge of the backlight structures. 
     
     
       20. The electronic device defined in  claim 18  wherein the portion of the second flexible printed circuit forms a portion of a shield can for the printed circuit board. 
     
     
       21. The electronic device defined in  claim 18  wherein the first, second, and third flexible printed circuits each have a portion that forms an integral layer of the printed circuit board. 
     
     
       22. The electronic device defined in  claim 10 , wherein the edge and the additional edge are opposing edges of the plurality of rigid printed circuit board layers.

Description:
This application claims priority to U.S. provisional patent application No. 61/707,768 filed Sep. 28, 2012, which is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     This relates generally to electronic devices, and more particularly, to electronic devices with displays. 
     Electronic devices often include displays. For example, cellular telephones and portable computers often include displays for presenting information to a user. An electronic device may have a housing such as a housing formed from plastic or metal. Components for the electronic device such as display components may be mounted in the housing. 
     It can be challenging to incorporate a display into the housing of an electronic device. Size, weight, electrical grounding, robustness, ease of assembly, and light-tightness are often important considerations in designing electronic devices. If care is not taken, displays may be bulky, may exhibit undesired light reflections, or it may be difficult to replace components of the display. 
     It would therefore be desirable to be able to provide improved displays for electronic devices. 
     SUMMARY 
     An electronic device may be provided with a display. The display may have display layers for displaying images. Backlight structures may be included in the display. The backlight structures may provide backlight that illuminates the display layers in the display that are displaying an image for a user. 
     The electronic device may include printed circuits such as printed circuit boards and flexible printed circuits. Flexible printed circuits may include flexible printed circuits that are separate from a printed circuit board and/or flexible printed circuits formed from a flexible layer of a printed circuit boards that extends from an edge of the printed circuit board. 
     The backlight structures and the printed circuit board may generate electromagnetic signals such as light leakage from the backlight structures and electromagnetic interfering signals from the printed circuit board. Flexible printed circuits may be used to prevent this type of light leakage and/or electromagnetic interfering signal from reaching other components in the device or from escaping from the device. Flexible printed circuits that are used as light shields in an electronic device in this way may also provide electrical grounding connections and other electrical connections between components in the device. 
     A flexible printed circuit may be wrapped around an edge of the backlight structures to form a light shield that prevents light leakage from the backlight structures into other portions of the electronic device. This type of flexible printed circuit that is wrapped around an edge of backlight structures to form a light shield may have an end that is attached to a portion of the display and an opposing end that is attached to a grounding structure. The grounding structure may be a metal support structure such as a metal chassis for the backlight structures or may be a portion of a printed circuit board. 
     A flexible printed circuit may be an extended layer of a printed circuit board having a portion that is attached to the metal chassis for the display and that forms an electrical grounding connection between the printed circuit board and the metal chassis. 
     A flexible printed circuit may be an extended layer of a printed circuit board that is wrapped around a surface of the printed circuit board over electronic components on the printed circuit board forming some or all of a electromagnetic shield structure between the electronic components and other components in the device. A flexible printed circuit that is wrapped around a printed circuit board to form a shielding structure in this way may have an end that is attached to an additional flexible printed circuit that is wrapped around an edge of the backlight structures to form a light shield that prevents light leakage from the backlight structures 
     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 electronic device such as a laptop computer with a display in accordance with an embodiment of the present invention. 
         FIG. 2  is a perspective view of an illustrative electronic device such as a handheld electronic device with a display in accordance with an embodiment of the present invention. 
         FIG. 3  is a perspective view of an illustrative electronic device such as a tablet computer with a display in accordance with an embodiment of the present invention. 
         FIG. 4  is a schematic diagram of an illustrative electronic device with a display in accordance with an embodiment of the present invention. 
         FIG. 5  is a cross-sectional side view of an illustrative display in accordance with an embodiment of the present invention. 
         FIG. 6  is a cross-sectional side view of illustrative display layers and backlight structures in accordance with an embodiment of the present invention. 
         FIG. 7  is a cross-sectional side view of an illustrative flexible circuit light shield that is coupled between display layers and a metal chassis for the display in accordance with an embodiment of the present invention. 
         FIG. 8  is a cross-sectional side view of illustrative flexible circuit shielding structures and grounding structures that are formed from an extended flexible layer of a printed circuit board in accordance with an embodiment of the present invention. 
         FIG. 9  is a perspective view of an illustrative flexible circuit light shield that is coupled between display layers and a printed circuit board showing how portions of the flexible printed circuit shield may include conductive traces for transmitting signals to the display in accordance with an embodiment of the present invention. 
         FIG. 10  is top view of illustrative display layers showing how flexible circuit light shield structures may be attached to multiple edges of the display layers in accordance with an embodiment of the present invention. 
         FIG. 11  is a top view of an illustrative printed circuit board having layers extending from multiple edges that form flexible printed circuits that can be used as shielding structures in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices may include displays. The displays may be used to display images to a user. Illustrative electronic devices that may be provided with displays are shown in  FIGS. 1, 2, and 3 . 
       FIG. 1  shows how electronic device  10  may have the shape of a laptop computer having upper housing  12 A and lower housing  12 B with components such as keyboard  16  and touchpad  18 . Device  10  may have hinge structures  20  that allow upper housing  12 A to rotate in directions  22  about rotational axis  24  relative to lower housing  12 B. Display  14  may be mounted in upper housing  12 A. Upper housing  12 A, which may sometimes referred to as a display housing or lid, may be placed in a closed position by rotating upper housing  12 A towards lower housing  12 B about rotational axis  24 . 
       FIG. 2  shows how electronic device  10  may be a handheld device such as a cellular telephone, music player, gaming device, navigation unit, or other compact device. In this type of configuration for device  10 , housing  12  may have opposing front and rear surfaces. Display  14  may be mounted on a front face of housing  12 . Display  14  may, if desired, have a display cover layer or other exterior layer that includes openings for components such as button  26 . Openings may also be formed in a display cover layer or other display layer to accommodate a speaker port (see, e.g., speaker port  28  of  FIG. 2 ). 
       FIG. 3  shows how electronic device  10  may be a tablet computer. In electronic device  10  of  FIG. 3 , housing  12  may have opposing planar front and rear surfaces. Display  14  may be mounted on the front surface of housing  12 . As shown in  FIG. 3 , display  14  may have a cover layer or other external layer with an opening to accommodate button  26  (as an example). 
     The illustrative configurations for device  10  that are shown in  FIGS. 1, 2, and 3  are merely illustrative. In general, electronic device  10  may be 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. 
     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 or cast 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. 
     Displays for device  10  may, in general, include image pixels formed from light-emitting diodes (LEDs), organic LEDs (OLEDs), plasma cells, electrowetting pixels, electrophoretic pixels, liquid crystal display (LCD) components, or other suitable image pixel structures. In some situations, it may be desirable to use LCD components to form display  14 , so configurations for display  14  in which display  14  is a liquid crystal display are sometimes described herein as an example. It may also be desirable to provide displays such as display  14  with backlight structures, so configurations for display  14  that include a backlight unit may sometimes be described herein as an example. Other types of display technology may be used in device  10  if desired. The use of liquid crystal display structures and backlight structures in device  10  is merely illustrative. 
     A display cover layer may cover the surface of display  14  or a display layer such as a color filter layer or other portion of a display may be used as the outermost (or nearly outermost) layer in display  14 . A display cover layer or other outer display layer may be formed from a transparent glass sheet, a clear plastic layer, or other transparent member. 
     Touch sensor components such as an array of capacitive touch sensor electrodes formed from transparent materials such as indium tin oxide may be formed on the underside of a display cover layer, may be formed on a separate display layer such as a glass or polymer touch sensor substrate, or may be integrated into other display layers (e.g., substrate layers such as a thin-film transistor layer). 
     A schematic diagram of an illustrative configuration that may be used for electronic device  10  is shown in  FIG. 4 . As shown in  FIG. 4 , electronic device  10  may include control circuitry  29 . Control circuitry  29  may include storage and processing circuitry for controlling the operation of device  10 . Control circuitry  29  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  29  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. 
     Control circuitry  29  may be used to run software on device  10 , such as operating system software and application software. Using this software, control circuitry  29  may present information to a user of electronic device  10  on display  14 . When presenting information to a user on display  14 , sensor signals and other information may be used by control circuitry  29  in making adjustments to the strength of backlight illumination that is used for display  14 . 
     Input-output circuitry  30  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 circuitry  30  may include communications circuitry  32 . Communications circuitry  32  may include wired communications circuitry for supporting communications using data ports in device  10 . Communications circuitry  32  may also include wireless communications circuits (e.g., circuitry for transmitting and receiving wireless radio-frequency signals using antennas). 
     Input-output circuitry  30  may also include input-output devices  34 . A user can control the operation of device  10  by supplying commands through input-output devices  34  and may receive status information and other output from device  10  using the output resources of input-output devices  34 . 
     Input-output devices  34  may include sensors and status indicators  36  such as an ambient light sensor, a proximity sensor, a temperature sensor, a pressure sensor, a magnetic sensor, an accelerometer, 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  38  may include speakers and tone generators for presenting sound to a user of device  10  and microphones for gathering user audio input. 
     Display  14  may be used to present images for a user such as text, video, and still images. Sensors  36  may include a touch sensor array that is formed as one of the layers in display  14 . 
     User input may be gathered using buttons and other input-output components  40  such as touch pad sensors, buttons, joysticks, click wheels, scrolling wheels, touch sensors such as sensors  36  in display  14 , key pads, keyboards, vibrators, cameras, and other input-output components. 
     A cross-sectional side view of an illustrative configuration that may be used for display  14  of device  10  (e.g., for display  14  of the devices of  FIG. 1 ,  FIG. 2 , or  FIG. 3  or other suitable electronic devices) is shown in  FIG. 5 . As shown in  FIG. 5 , display  14  may include one or more layers of touch sensitive components such as touch-sensitive layers  47  that are attached to a cover layer such as cover layer  49 . Cover layer  49  may be formed from a sheet of rigid or flexible transparent material such as glass or plastic. 
     Touch-sensitive layers  47  may be attached to cover layer  49  using an adhesive material such as optically clear adhesive (OCA)  43 . Adhesive  43  may be a liquid adhesive, light-cured adhesive, pressure-sensitive adhesive or other suitable adhesive. Touch-sensitive layers  47  may include touch sensor components such as an array of capacitive touch sensor electrodes formed from transparent materials such as indium tin oxide. 
     Display  14  may include display layers such as layers  46  for generating images to be displayed on display  14 . Display layers  46  may include polarizer layers, color filter layers, transistor layers, adhesive layers, layers of liquid crystal material, or other layers for generating display images. Display layers  46  may be attached to touch-sensitive layers  43  using adhesive such as optically clear adhesive  45 . Adhesive  45  may be a liquid adhesive, light-cured adhesive, pressure-sensitive adhesive or other suitable adhesive. 
     Display layers  46  may use light generated by light-generating structures such as backlight structures  42  to form images to be viewed by a user of device  10 . Backlight structures  42  may include light-generating components such as light-emitting diodes, light guiding structures, reflective structures, optical films, etc. Backlight structures  42  may be attached to display layers  46  or may be mounted adjacent to layers  46  by attaching backlight structures  42  to one or more structural members. 
     A cross-sectional side view of an illustrative configuration that may be used for display layers  46  and backlight structures  42  of display  14  (e.g., for display layers  46  and backlight structures  42  of the display of  FIG. 5 , or other suitable display) is shown in  FIG. 6 . As shown in  FIG. 6 , display  14  may include backlight structures such as backlight unit  42  for producing backlight  44 . During operation, backlight  44  travels outwards (vertically upwards in dimension Z in the orientation of  FIG. 6 ) and passes through display pixel structures in display layers  46 . This illuminates any images that are being produced by the display pixels for viewing by a user. For example, backlight  44  may illuminate images on display layers  46  that are being viewed by viewer  48  in direction  50 . 
     Display layers  46  may be mounted in chassis structures such as a plastic chassis structure and/or a metal chassis structure to form a display module for mounting in housing  12  or display layers  46  may be mounted directly in housing  12  (e.g., by stacking display layers  46  into a recessed portion in housing  12 ). Display layers  46  may form a liquid crystal display or may be used in forming displays of other types. 
     In a configuration in which display layers  46  are used in forming a liquid crystal display, display layers  46  may include a liquid crystal layer such a liquid crystal layer  52 . Liquid crystal layer  52  may be sandwiched between display layers such as display layers  58  and  56 . Layers  56  and  58  may be interposed between lower polarizer layer  60  and upper polarizer layer  54 . If desired, upper polarizer layer  54  may be attached to an outer cover layer such as cover layer  49  ( FIG. 5 ). 
     Layers  58  and  56  may be formed from transparent substrate layers such as clear layers of glass or plastic. Layers  56  and  58  may be layers such as a thin-film transistor layer and/or a color filter layer. Conductive traces, color filter elements, transistors, and other circuits and structures may be formed on the substrates of layers  58  and  56  (e.g., to form a thin-film transistor layer and/or a color filter layer). Touch sensor electrodes may also be incorporated into layers such as layers  58  and  56  and/or touch sensor electrodes may be formed on other substrates. 
     With one illustrative configuration, layer  58  may be a thin-film transistor layer that includes an array of thin-film transistors and associated electrodes (display pixel electrodes) for applying electric fields to liquid crystal layer  52  and thereby displaying images on display  14 . Layer  56  may be a color filter layer that includes an array of color filter elements for providing display  14  with the ability to display color images. If desired, layer  58  may be a color filter layer and layer  56  may be a thin-film transistor layer. 
     During operation of display  14  in device  10 , control circuitry  29  (e.g., one or more integrated circuits such as components  68  on printed circuit  66  of  FIG. 6 ) may be used to generate information to be displayed on display (e.g., display data). The information to be displayed may be conveyed from circuitry  68  to display driver integrated circuit  62  using a signal path such as a signal path formed from conductive metal traces in flexible printed circuit  64  (as an example). 
     Display driver integrated circuit  62  may be mounted on thin-film-transistor layer driver ledge  82  or elsewhere in device  10 . A flexible printed circuit cable such as flexible printed circuit  64  may be used in routing signals between printed circuit  66  and thin-film-transistor layer  58 . If desired, display driver integrated circuit  62  may be mounted on printed circuit  66  or flexible printed circuit  64 . 
     Printed circuit  66  may be formed from a rigid printed circuit board (e.g., a layer of fiberglass-filled epoxy) or a flexible printed circuit (e.g., a flexible sheet of polyimide or other flexible polymer layer). However, these examples are merely illustrative. If desired printed circuits  64  and  66  may be formed from a combination of rigid and flexible printed circuit layers (e.g., printed circuit  66  may be formed from a rigid printed circuit board with a layer of flexible printed circuitry that extends from an edge of printed circuit  66  to form flexible printed circuitry  64  that attaches to thin-film-transistor layer  58 ). 
     Backlight structures  42  may include a backlight light guide plate such as light guide plate  78 . Light guide plate  78  may be formed from a transparent material such as clear glass or plastic. During operation of backlight structures  42 , a light source such as light source  72  may generate light  74 . Light source  72  may be, for example, an array of light-emitting diodes. 
     Light  74  from light source  72  may be coupled into edge surface  76  of light guide plate  78  and may be distributed laterally in dimensions X and Y throughout light guide plate  78  due to the principal of total internal reflection. Light guide plate  78  may include light-scattering features such as pits or bumps or other light-scattering structures. The light-scattering features may be located on an upper surface and/or on an opposing lower surface of light guide plate  78 . 
     Light  74  that scatters upwards in direction Z from light guide plate  78  may serve as backlight  44  for display  14 . Light  74  that scatters downwards may be reflected back in the upwards direction by reflector  80 . Reflector  80  may be formed from a reflective material such as a layer of white plastic or other shiny materials. 
     To enhance backlight performance for backlight structures  42 , backlight structures  42  may include optical films  70 . Optical films  70  may include diffuser layers for helping to homogenize backlight  44  and thereby reduce hotspots, compensation films for enhancing off-axis viewing, and brightness enhancement films (also sometimes referred to as turning films) for collimating backlight  44 . Optical films  70  may overlap the other structures in backlight unit  42  such as light guide plate  78  and reflector  80 . For example, if light guide plate  78  has a rectangular footprint in the X-Y plane of  FIG. 6 , optical films  70  and reflector  80  may have a matching rectangular footprint. 
     Some portion of light  74  from light source  72  may escape from light guide plate  78 , may be reflected from an edge of light guide plate  78 , or may otherwise leak away from light source  72 . Flexible printed circuits such a flexible printed circuit  64  may be wrapped around an edge of backlight structures  42  so that a portion of light  74  that leaks away from light sources such as light source  72  is blocked from escaping from the display into other portions of device  10 . Flexible printed circuit  64  or other light shielding flexible printed circuits in device  10  may be formed from a continuous sheet of opaque flexible printed circuit material to form a complete light blocking flexible printed circuit. 
     Flexible printed circuit  64  may be attached to ledge  82  using anisotropic conductive adhesive (AFC) or other conductive adhesive. Flexible printed circuit  64  may be attached to printed circuit  66  using AFC, solder, connector structures, or flexible printed circuit  64  may be formed from an integral layer of printed circuit  66  that extends from an edge of printed circuit  66 . 
     As shown in  FIG. 7 , device  10  may be provided with one or more additional flexible printed circuit light shields such as flexible printed circuit  102  that are separate from other printed circuitry in the device. Flexible printed circuit  102  may be attached to ledge  82  of display layers  46  in gap  103  using anisotropic conductive adhesive (AFC) or other conductive adhesive. Gap  103  may have a thickness (i.e., a minimum distance between touch-sensitive layer  47  and ledge  82 ) of less than 1 mm, less than 0.5 mm, less than 0.3 mm, between 0.2 mm and 0.3 mm, or between 0.1 mm and 0.5 mm (as examples). 
     Light such as light  74 ′ that escapes from backlight structures  42  may be prevented from reaching other portions of device  10  by flexible printed circuit  102 . Flexible printed circuit  102  may prevent light  74 ′ from reaching other components such as component  101  in device  10 . Component  101  may be, for example, an antenna that could be negatively affected by radiation from display  14 . 
     Flexible printed circuit  102  may also provide an electrical connection such as a grounding connection between display layers  46  and a metal support member such as metal chassis  100  for backlight structures  42 . Flexible printed circuit  102  may be attached to metal chassis  100  using adhesive  104  (e.g., a conductive pressure sensitive adhesive (PSA)). 
     In some situations, it may be desirable to replace backlight structures  42  during the lifetime of a device without removing flexible printed circuit  102  from a small gap such as gap  103 . In this type of situation, flexible printed circuit  102  may be detached from metal chassis  100 , replacement backlight structures may be attached to display layers  46 , and flexible printed circuit  102  may be attached to the replacement backlight structures using additional adhesive such as pressure sensitive adhesive. In this way, display  14  may be provided with a light shielding and electrical grounding structure that does not prevent reworking of the display during, for example, manufacturing or repair operations for the device. 
     Flexible printed circuit  102  may include a conductive layer coupled between display layers  46  and metal chassis  100 . The conductive layer may be a continuous conductive layer that is encased in a flexible substrate such as a flexible sheet of polyimide or other flexible polymer layer. Flexible printed circuit  102  may, if desired, extend continuously along and edge of backlight structures  42  so that light  74 ′ is prevented from escaping from substantially all of the edge of backlight structures  42 . Display  14  may be provided with a flexible printed circuit light shield such as flexible printed circuit  102  along one, two, three, four, or more edges of display layers  46  and backlight structures  42 . 
     As shown in  FIG. 8 , flexible printed circuit  64  and other flexible printed circuits such as flexible printed circuits  106  and  108  may be formed from one or more extended layers of printed circuit board  66  (e.g., flexible printed circuits  64 ,  106  and  108  may be extended portions of a common layer of printed circuit board  66  or may be extended portions of two or more layers of printed circuit board  66 ). Printed circuit board  66  and other printed circuits in device  10  may contain a stack of multiple layers such as layers  31 . For example, a printed circuit may contain a combination of both rigid and flexible layers (sometimes referred to as a “rigid-flex” PCB). 
     A multi-layer printed circuit such as printed circuit  66  may sometimes be referred to as a PCB stack or PCB stack-up. Layers  31  of PCB  66  may be formed from dielectrics such as fiberglass-filled epoxy (e.g., as a rigid layer in a PCB stack) and polyimide (e.g., as a flexible layer in a PCB stack), FR-2 (phenolic cotton paper), FR-3 (cotton paper and epoxy), FR-4 (woven glass and epoxy), FR-5 (woven glass and epoxy), FR-6 (matte glass and polyester), G-10 (woven glass and epoxy), CEM-1 (cotton paper and epoxy), CEM-2 (cotton paper and epoxy), CEM-3 (woven glass and epoxy), CEM-4 (woven glass and epoxy), CEM-5 (woven glass and polyester), paper impregnated with phenolic resin, polystyrene, polyimide, polytetrafluoroethylene (PTFE), plastic, other polymers, ceramics, or other suitable dielectrics. 
     Layers  31  may include attachment layers such as layers of prepreg (i.e., pre-impregnated layers of fiber and resin). Layers of copper or other conductive materials may be formed on the surfaces of layers  31 . For example, one or more of layers  31  may have upper and lower surfaces that are covered with a layer of metal such as copper. 
     Integrated circuits, discrete components such as resistors, capacitors, and inductors, and other electronic components  68  may be mounted to PCB  66 . Display driver circuitry  62  ( FIG. 6 ) may receive image data from processing circuitry in PCB  66  (e.g., from integrated circuits such as components  68 ) and produce corresponding control signals for display  14 . 
     Flexible substrates such as flexible substrates  64 ,  106 , and  108  that extend from an edge of printed circuit board  66  may be used to route signals from PCB  66  to other components in device  10  or may be used to form electrical grounding connections between PCB  66  and other electrical components and conductive structures in device  10 . For example, as described above in connection with  FIG. 6 , flexible printed circuit  64  may be used to route signals from PCB  66  to display driver integrated circuit  62  or directly to thin-film transistor layer  58  from components  68  or other circuitry in PCB  66 . Flexible printed circuit  64  may be wrapped around an edge of backlight structures  42  so that light  74 ′ is prevented from escaping from device  10  or from reaching other components such as component  101 . 
     Printed circuit  66  may include additional extended flexible portions such as flexible printed circuit  106  that forms a grounding connection between PCB  66  and metal chassis  100  and/or flexible printed circuit  108  that forms a grounding connection between PCB  66  and flexible printed circuit  64 . Flexible printed circuits  106  and  108  may each include a conductive layer. The conductive layers in circuits  106  and  108  may be each encased in a flexible substrate such as a flexible sheet of polyimide or other flexible polymer layer. 
     Printed circuit  66  may be attached to backlight structures  42  using adhesive material  112 . Adhesive material  112  may be a conductive adhesive (e.g., a conductive pressure sensitive adhesive, an anisotropic conductive adhesive or a conductive light curable adhesive) that forms a conductive connection between PCB  66  and metal chassis  100 . However, this is merely illustrative. If desired, PCB  66  may be attached to backlight structures  42  using a non-conductive (insulating) adhesive or PCB  66  may be formed separately from backlight structures  42 . 
     Flexible printed circuit  106  may be attached to metal chassis  100  using adhesive  114 . Adhesive material  114  may be a conductive adhesive (e.g., a conductive pressure sensitive adhesive, an anisotropic conductive adhesive or a conductive light curable adhesive) that forms a conductive connection between PCB  66  and metal chassis  100 . Adhesive  114  and flexible printed circuit  106  may be used to form a conductive ground connection between PCB  66  and metal chassis  100 . 
     In some situations it may be desirable to replace a backlight unit such as backlight unit  42  or to replace display layers  46 , cover layer  29  and touch-sensor layer  47  during the lifetime of a device such as device  10  (e.g., during device testing and assembly operations or during device repair operations) without disturbing flexible printed circuit  64  in gap  103 . For example, in a drop event, backlight unit  42  may be damaged. In this type of situation, backlight structures  42  may be replaced by detaching PCB  66  and/or flexible printed circuit  106  from backlight structures  42 , removing adhesives  112  and  114 , removing backlight structures  42  from display layers  46 , attaching replacement backlight structures to display layers  46 , and attaching PCB  66  and/or flexible printed circuit  106  to the replacement backlight structures using conductive or non-conductive adhesive. 
     As shown in  FIG. 8 , flexible printed circuit  108  may extend from one edge of PCB  66  and may be wrapped over a surface of PCB  66  and attached to a conductive surface such as flexible printed circuit  64  (e.g., using adhesive such as conductive adhesive  116 ) near an opposing edge of PCB  66 . Flexible printed circuit  108  may include a continuous conductive layer that passes over the surface of PCB  66 . In this way, flexible printed circuit  108  may form at least a portion of a conductive shield (sometimes referred to as a shield can or Faraday cage) over components  68  and PCB  66 . 
     PCB  66  and/or components  68  may generate electromagnetic interference (EMI) in the form of electromagnetic radiation that is emitted from one or more components  68  and/or PCB  66 . This type of EMI can, if allowed to propagate into other portions of a device, interfere with the operation of other components in the device such an antenna, a compass, or other electromagnetically-sensitive components. Flexible printed circuit  108  may help contain electromagnetic signals from PCB  66  and/or components  68 , thereby preventing these signals from affecting other components in device  10 . 
     Flexible printed circuit  108  may be wrapped around PCB  66  so that a surface of flexible printed circuit  108  is formed in contact with one or more components  68  or PCB  66  may be provided with standoff structures  110  that form conductive contacts with portions of flexible printed circuit  108 . 
     Standoff structures  110  may be formed from conductive materials such as conductive foam or metal (e.g., stainless steel or metal alloys) formed on the surface of PCB  66 . Conductive support structures  110  may be formed along one or more edges (or along all edges) of a component so that support structures  110  and a portion of flexible printed circuit  108  form a conductive cover for that component. This type shield can over components  68  formed from members  110  and flexible printed circuit  108  may help prevent EMI from those components from affecting other components and prevent EMI from other components in device  10  from affecting those components that are covered. 
     Standoff structures  110  may be formed adjacent to the edges of each component  68 , adjacent to the edges of some components  68 , or along the edges of PCB  66  so that flexible printed circuit  108  and standoff structures  110  form a single shield can that covers substantially all of the surface of PCB  66 . 
       FIG. 9  is a perspective view of flexible printed circuit  64  showing how flexible printed circuit  64  may be formed from a continuous sheet of flexible printed circuitry that extends along substantially all of an edge of backlight structures  42 . In this way portions of the light that may leak from backlight structures  42  may be blocked by flexible printed circuit light shield  64 . 
     As shown in  FIG. 9 , flexible printed circuit  64  may have portions such as portions  120  that contain signal lines for carrying signals between display  14  and PCB  66  and portions  122  that are free of signal lines. Portions  120  of flexible substrate  64  may contain patterned conductive traces  124  (e.g., conductive traces on flexible sheets of substrate such as polyimide sheets). Patterned conductive traces  124  may form signal lines that convey signals from PCB  66  (e.g., from integrated circuits such as components  68 ) to display circuitry such as display driver circuitry  62  ( FIG. 6 ) or directly to thin-film transistors in layer  58 . 
     Portions  122  of flexible printed circuit  64  may include sheets of opaque material  126  that prevent light from passing through circuit  64 . Material  126  may include sheets of conductive material that form an electrical grounding connection between display layer  46  and PCB  66  or may be a non-conductive opaque material. Material  126  may be formed as an inner layer of flexible printed circuit  64  (e.g., a conductive layer that is embedded in a flexible substrate such polyimide), may be formed as an outer layer of flexible printed circuit  64 , or may form substantially all of portions  122  of flexible printed circuit  64 . Portions  120  may also be formed using opaque material that prevents light from passing through portions  120 . 
     Portions  120  may have respective widths W1 and W2 along the edge of display layers  46 . Widths W1 and W2 may be determined by the number of traces  124  to be used in communicating signals between PCB  66  and display layers  46 . 
     In the example of  FIG. 9 , flexible printed circuit  64  includes two signal line carrying portions  120  and three portions  122  that are free of signal traces. However, this is merely illustrative. If desired, flexible printed circuit  64  may include one portion  120 , two portions  120 , three portions  120 , more than three portions  120  or may be free of signal traces. Flexible printed circuit may include one portion  122 , two portions  122 , three portions  122 , four portions  122 , more than four portions  122  or may include signal traces formed along substantially all of flexible printed circuit  64 . 
       FIG. 10  is a top view of display layers  46  showing how multiple light shielding flexible printed circuits may be attached to the edges of display layers  46 . In the example of  FIG. 10 , ledge  82  of display layers  46  runs along substantially all of the perimeter of display layers  46  (e.g., along all four edges of display layers  46 ). 
     In this configuration, device  10  may include flexible printed circuit light shields such as flexible printed circuits  64 ,  130 ,  132 , and  134  attached to respective first, second, third and fourth edge portions of ledge  82 . However, this is merely illustrative. If desired, ledge  82  may be formed along one, two, three or four edges of display layers  46 . If desired, display  14  can have one, two, three, four or more than four flexible printed circuit light shields attached to one, two, three, four or more than four edges of display layers  46 . If desired, flexible printed circuit light shields such as flexible printed circuits  64 ,  130 ,  132 , and  134  may be attached to other portions of display layers  46  or other structures in display  14 . 
     Each of flexible printed circuits  64 ,  130 ,  132 , and  134  may be formed separately from printed circuit board  66  or may be formed as integral layers of PCB  66 . 
     As shown in  FIG. 11 , printed circuit board  66  may be a “rigid-flex” circuit that includes flexible layers that extend from multiple edges of PCB  66  forming multiple corresponding flexible printed circuits. In the example of  FIG. 11 , PCB  66  includes flexible printed circuits  64 ,  136 , and  140  that extend from respective first, second, and third edges of PCB  66  and span substantially all of that edge of PCB  66 . PCB  66  also may include flexible printed circuit  138  that extends from a fourth edge of PCB  66  and spans a portion of that fourth edge. However, this is merely illustrative. If desired, PCB  66  may include flexible printed circuits that extend from one, two, three or more edges of PCB  66 . If desired, each flexible printed circuit may span some or all of the edge from which it extends. If desired, any or all of flexible printed circuits  64 ,  136 ,  138 , and  140  may be attached to a surface of PCB  66  using connectors or conductive adhesive material such as anisotropic conductive adhesive or solder. 
     Flexible printed circuits  140 ,  136 , and  138  may extend from PCB  66  around portions of display  14  to form flexible printed circuit light shields such as flexible printed circuits  134 ,  132 , and  130  of  FIG. 10 . If desired, an extended flexible layer of PCB  66  such as one of flexible printed circuits  140 ,  136 , and  138  may be used to form flexible printed circuits  106  and/or  108  of  FIG. 8 . 
     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: 20130219
Publication Date: 20180327
Grant Date: 20180327
Priority Date: 20120928
Inventors: FRANKLIN JEREMY C.
GIBBS KEVIN D.
QIAN AMY
RAFF JOHN
PETERSON CARL R.
Assignee: APPLE INC
CPC Classifications: [{"code": "H05K1/0274", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2201/10128", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/189", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09F13/0413", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K1/147", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/028", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2201/10128", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/189", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/147", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/028", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/0274", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G3/20", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09F13/0413", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2330/06", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2300/0426", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2201/10128", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/147", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/189", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/0274", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 50384678