PATENT DOCUMENT

Publication Number: US-9454025-B2
Application Number: US-201213600862-A
Country: US
Kind Code: B2

Title: Displays with reduced driver circuit ledges

Abstract:
An electronic device display may have a color filter layer, a thin-film-transistor layer, and a layer of liquid crystal material. The display may have a display cover layer such as a layer of glass or plastic. Adhesive may be used to attach the upper polarizer to the display cover layer. The thin-film transistor layer may have a substrate with upper and lower surfaces. Thin-film-transistor circuitry may be formed on the upper surface. A display driver integrated circuit may be mounted to the lower surface or a flexible printed circuit and may be coupled to the thin-film-transistor circuitry using wire bonding wires. Through vias that are formed through the thin-film-transistor layer substrate may be used in coupling the thin-film-transistor circuitry to the display driver integrated circuit.

Claims:
What is claimed is: 
     
       1. A display having an active area surrounded by an inactive border region, the display comprising:
 a color filter layer; 
 a thin-film-transistor layer having thin-film-transistor circuitry and having a substrate with first and second opposing surfaces, wherein the thin-film transistor circuitry is formed on the first surface; 
 a layer of liquid crystal material interposed between the color filter layer and the thin-film transistor layer; and 
 a display driver integrated circuit mounted on the second surface, wherein the color filter layer overlaps the display driver integrated circuit in the inactive border region of the display, wherein the substrate has conductive vias that pass vertically through the substrate from the first surface to the second surface and that couple the thin-film-transistor circuitry to the display driver integrated circuit. 
 
     
     
       2. The display defined in  claim 1  wherein the substrate comprises glass and wherein the vias comprise wires embedded in the glass. 
     
     
       3. The display defined in  claim 1  wherein the substrate comprises glass and wherein the vias comprise laser-drilled holes in the glass. 
     
     
       4. The display defined in  claim 1  wherein the substrate comprises glass. 
     
     
       5. A display, comprising:
 a color filter layer; 
 a thin-film-transistor layer having thin-film-transistor circuitry and having a substrate with first and second opposing surfaces, wherein the thin-film transistor circuitry is formed on the first surface; 
 a layer of liquid crystal material interposed between the color filter layer and the thin-film transistor layer; 
 a flexible printed circuit having a first portion that is mounted to the second surface and a second portion that extends away from the second surface, wherein the first and second portions are connected by a bent portion of the flexible printed circuit; and 
 a display driver integrated circuit mounted on the second portion of the flexible printed circuit, wherein the substrate has conductive vias that pass vertically through the substrate from the first surface to the second surface and that couple the thin-film-transistor circuitry to the flexible printed circuit. 
 
     
     
       6. The display defined in  claim 5  wherein the second portion extends away from the second surface at a perpendicular angle. 
     
     
       7. The display defined in  claim 6  wherein the substrate comprises glass. 
     
     
       8. The display defined in  claim 5  wherein the substrate comprises glass and wherein the vias comprise laser-drilled holes in the glass. 
     
     
       9. The display defined in  claim 5  wherein the substrate comprises glass. 
     
     
       10. The display defined in  claim 9  wherein the vias comprise wires embedded in the glass. 
     
     
       11. A display, comprising:
 a color filter layer; 
 a thin-film-transistor layer having thin-film-transistor circuitry; 
 a layer of liquid crystal material interposed between the color filter layer and the thin-film transistor layer, wherein the thin-film-transistor layer has a ledge region that is uncovered by the color filter layer; 
 a display driver integrated circuit; and 
 wire bonding wires that extend between the thin-film-transistor circuitry in the ledge region and the display driver integrated circuit, wherein each wire bonding wire forms a wire bond connection with a conductive trace on the thin-film-transistor layer, wherein the thin-film-transistor layer has a substrate with upper and lower surfaces, wherein the thin-film-transistor circuitry is formed on the upper surface, wherein the display driver integrated circuit is mounted on the lower surface, wherein the substrate has a conductive line on the lower surface, and wherein at least a portion of the conductive line is interposed between the display driver integrated circuit and the lower surface. 
 
     
     
       12. The display defined in  claim 11  wherein the display driver integrated circuit is electrically connected to the conductive line on the lower surface. 
     
     
       13. The display defined in  claim 11  further comprising a black masking layer interposed between the color filter layer and the thin-film-transistor layer in an inactive border region. 
     
     
       14. A display, comprising:
 a color filter layer; 
 a thin-film-transistor layer having thin-film-transistor circuitry; 
 a layer of liquid crystal material interposed between the color filter layer and the thin-film transistor layer, wherein the thin-film-transistor layer has a ledge region that is uncovered by the color filter layer; 
 a flexible printed circuit; 
 a display driver integrated circuit mounted on and electrically connected to a conductive trace on the flexible printed circuit; and 
 a wire bonding wire the extends between the thin-film-transistor circuitry in the ledge region and a first wire bond connection on the flexible printed circuit to form a signal path between the display driver integrated circuit and the thin-film-transistor circuitry, wherein the wire bonding wire forms a second wire bond connection with a conductive trace on the thin-film-transistor layer, and wherein the conductive trace on the flexible printed circuit extends from the display driver integrated circuit to the first wire bond connection. 
 
     
     
       15. The display defined in  claim 14  wherein the thin-film-transistor layer has a substrate with upper and lower surfaces, wherein the thin-film-transistor circuitry is formed on the upper surface, and wherein the flexible printed circuit includes at least a portion that is mounted on the lower surface. 
     
     
       16. The display defined in  claim 15  further comprising a black masking layer interposed between the color filter layer and the thin-film-transistor layer in an inactive border region.

Description:
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 and weight are often important considerations in designing electronic devices. If care is not taken, displays may be bulky or may be surrounded by overly large borders. 
     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 having upper and lower polarizers. The display may have a color filter layer, a thin-film-transistor layer, and a layer of liquid crystal material interposed between the color filter layer and the thin-film-transistor layer. The color filter layer and thin-film-transistor layer may be interposed between the upper and lower polarizers. The display may have a display cover layer such as a layer of glass or plastic. Adhesive may be used to attach the upper polarizer to the display cover layer. 
     The thin-film transistor layer may have a substrate such as a layer of glass with opposing upper and lower surfaces. Thin-film-transistor circuitry may be formed on the upper surface. A display driver integrated circuit may be mounted to the lower surface or may be mounted to a flexible printed circuit. Wire bonding wires may be used to couple the thin-film-transistor circuitry to a display driver integrated circuit on the lower surface or may be used to couple the thin-film-transistor circuitry to a flexible printed circuit to which a display driver integrated circuit has been mounted. 
     Through vias may be formed through the thin-film-transistor layer substrate. The through vias may be used in coupling a display driver integrated circuit to the thin-film transistor circuitry or may be used to couple the thin-film-transistor circuitry to a flexible printed circuit to which a display driver integrated circuit is mounted. 
     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 an illustrative display having wire bond connections that have been used to interconnect thin-film-transistor circuitry on the upper surface of a thin-film-transistor layer with flexible printed circuit structures on the lower surface of the thin-film transistor layer in accordance with an embodiment of the present invention. 
         FIG. 7  is a cross-sectional side view of an illustrative display in which a driver integrated circuit has been mounted on the lower surface of a thin-film-transistor layer and in which wire bond connections have been used to connect thin-film-transistor circuitry on the upper surface of the thin-film-transistor layer to the driver integrated circuit in accordance with an embodiment of the present invention. 
         FIG. 8  is a cross-sectional side view of an illustrative electronic device having a display in which a flexible printed circuit bus is being used to connect a driver integrated circuit to traces on an upper surface of a thin-film-transistor layer and in which optically clear adhesive is being used to attach display layers to a cover glass layer in accordance with an embodiment of the present invention. 
         FIG. 9  is a cross-sectional side view of an illustrative display in which through vias pass from the upper surface to the lower surface of the thin-film-transistor layer and in which a display driver circuit is coupled to the vias using a flexible printed circuit in accordance with an embodiment of the present invention. 
         FIG. 10  is a cross-sectional side view of an illustrative display in which through vias pass from the upper surface to the lower surface of the thin-film-transistor layer and in which a display driver circuit is mounted to the vias on the lower surface 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 (e.g., a color filter layer or thin-film-transistor 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 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, thin-film transistor layer or other portion of a display may be used as the outermost (or nearly outermost) layer in display  14 . For example, a color filter layer or thin-film transistor layer that is covered by a polarizer layer may form the outermost layer for device  10 . 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 backlight structures such as backlight unit  42  for producing backlight  44 . During operation, backlight  44  travels outwards (vertically upwards in the orientation of  FIG. 5 ) 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 . 
     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, the positions of color filter layer  56  and thin-film-transistor layer  58  may be inverted so that the thin-film-transistor layer is located above the color filter 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. 5 ) may be used to generate information to be displayed on display  14  (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  60 . 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). 
     Backlight structures  42  may include a 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 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. 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 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 when viewed in direction  50  of  FIG. 5  (i.e., when viewed as a top view), optical films  70  and reflector  80  may have a matching rectangular footprint. 
       FIG. 6  is a cross-sectional side view of an illustrative configuration that may be used for the structures of display  14  when it is desired to minimize the width of the inactive border region of the display  14 . As shown in  FIG. 6 , display  14  may have a ledge such as ledge  82  on thin-film-transistor layer  58  (i.e., a portion of layer  58  that is uncovered by color filter layer  56 ). The size of ledge  82  of thin-film-transistor layer  58  may be minimized by mounting driver integrated circuit  62  on flexible printed circuit  64 . 
     Thin-film-transistor layer  58  may include an array of display pixels. The display pixels may be controlled by signals that are routed over a grid of intersecting gate lines and data lines. Each display pixel may contain electrode structures for applying an electric field to an associated portion of liquid crystal layer  52 . Thin-film transistors may be provided in the display pixels to control the electric fields that are applied by the electrode structures. The thin-film transistors, gate lines, data lines, other conductive lines, and other thin-film circuitry (e.g., gate line driver circuitry) formed on the upper surface of thin-film-transistor layer  58  is shown as thin-film-transistor circuitry  106  of  FIG. 6 . 
     Circuitry  106  may be formed on a substrate such as substrate  108 . Substrate  108  may be formed from a sheet of clear glass or plastic or other transparent dielectric layer. Substrate  108  may have opposing planar upper and lower surfaces. Thin-film-circuitry  106  may be formed on the upper surface of substrate  108 . Thin-film-circuitry  106  may include conductive lines such as conductive gate lines and data lines and other conductive lines that are used in distributing signals on thin-film-transistor layer  58 . Conductive lines on thin-film-transistor layer  58  (e.g., metal traces or other conductive materials that are formed as part of thin-film-transistor circuitry  106  on the upper surface of thin-film-transistor substrate  108 ) are shown as lines  96  in  FIG. 6 . 
     Display driver integrated circuits such as display driver integrated circuit  62  of  FIG. 6  may be mounted on substrates such as flexible printed circuit  64 . Flexible printed circuit  64  may be attached to the lower surface of thin-film-transistor layer substrate  108  as shown in  FIG. 6  or may be mounted to other support structures within device  10 . 
     Flexible printed circuit  64  may include one or more layers of conductive lines  100  such as metal traces. Conductive lines  100  may serve as signal lines that distribute signals between display driver integrated circuit  62  and thin-film-transistor circuitry  106 . Conductive lines  100  may include parallel signal paths that form a signal bus. Each of conductive lines  100  may be coupled to a respective signal path such as one of wire bond wires  92 . 
     Each wire bonding wire  92  may have opposing first and second ends. The first end of each wire bonding wire  92  may be coupled to a respective one of traces  100  in flexible printed circuit  62  using a respective wire bond connection  98 . The second end of each wire bonding wire  92  may be connected to a respective one of traces  96  in thin-film-transistor circuitry  106  on the upper surface of thin-film-transistor layer substrate  108 . Wire bonding wires (wire bonds)  92  may be formed using a wire bonding tool. During wire bonding operations, the wire bonding head of the wire bonding tool and/or thin-film-transistor layer  58  may be positioned so that wire bonds  92  extend from the upper surface of thin-film-transistor layer  58  to the lower surface of thin-film transistor layer  58  (e.g., the exposed lower surface of flexible printed circuit layer  64 ). 
     Black masking material  90  may be formed around the inactive periphery (border) of display  14  between color filter layer  56  and thin-film-transistor layer  58 . Black masking material  90 , which may sometimes be referred to as opaque masking material, may be formed from a polymer containing carbon black or other material that absorbs visible light. Black masking material  90  may be patterned to form a strip that serves as an opaque border running around the rectangular periphery of display  14  overlapping inactive display components (e.g., display driver circuitry, a thin-film-transistor ledge, etc.) and helping to hide these components from view by a viewer such as viewer  48  of  FIG. 5 . Black masking material  90  may be deposited in a rectangular ring shape surrounding a central rectangular portion of display  14  that includes the display pixels for display  14 . 
     Another illustrative configuration that may be used in forming a display with a reduced inactive border region is shown in  FIG. 7 . As shown in  FIG. 7 , display driver circuitry such as one or more display driver integrated circuits  62  may be mounted on the lower surface of thin-film-transistor layer substrate  108 . Conductive lines  102  may be formed on the lower surface of thin-film-transistor layer substrate  108  (e.g., to form pads to which a flexible printed circuit cable may be attached). Wire bonding wires  92  may be used to form connections with display driver integrated circuit  62  directly at connections such as wire bond connection  98  and/or may be used to form connections with display driver integrated circuitry  62  by forming a connection such as connection  98 ′ with lower surface conductive lines  102 . In configurations in which wire bonding wires  92  terminate on conductive lines  102 , conductive lines  102  may be used to connect wires  92  to driver integrated circuit  62  (e.g., by using solder balls to flip-chip mount driver integrated circuit  62  to solder pads formed from conductive lines  102 . Each wire bonding wire  92  may have a connection such as wire bond  94  of  FIG. 7  with which that wire is connected to conductive lines on the upper surface of thin-film transistor layer  58 . 
     As shown in the cross-sectional side view of  FIG. 8 , another way in which the size of thin-film-transistor layer driver ledge  82  may be minimized involves mounting a display driver integrated circuit  62  on flexible printed circuit  64  (e.g., using solder or other connections between the circuitry of integrated circuit  62  and conductive lines  100 ) and using conductive lines  100  in flexible printed circuit  64  to route signals between display driver integrated circuit  62  and conductive lines  96  and other thin-film-transistor circuitry  106  on the upper surface of thin-film-transistor substrate layer  108 . Traces  100  may be coupled to traces  96  using conductive adhesive (anisotropic conductive film), welds, solder connections, board-to-board connectors, or other attachment mechanisms. Because display driver integrated circuit  62  need not be located on ledge  82  of thin-film-transistor layer  58 , the size of ledge  82  (and therefore the width of the inactive border portion of display  14  in the vicinity of ledge  82 ) may be minimized. 
     Displays such as display  14  of  FIG. 8  and other displays  14  for device  10  may have an optional display cover layer such as display cover layer  110 . Display cover layer  110  may be formed from a layer of clear glass, a layer of transparent plastic, a layer of transparent ceramic, or other transparent material. The thickness of display cover layer  110  may be, for example, 0.1 to 5 mm (as examples). 
     If desired, optically clear adhesive such as adhesive  104  may be used to attach display cover layer  110  to the outermost surface of upper polarizer  54 . When display cover layer  110  is attached to the layers of display  14  in this way, display cover layer  110  may exhibit a reduced likelihood of cracking during use of device  10 , allowing the thickness of display cover layer  110  to be reduced. Display cover layer  110  may, if desired, be formed from a relatively hard material (e.g., glass) to resist scratching. Black masking layers  90  may be formed around the periphery of display cover layer  110  to block internal device structures such as driver ledge  82  from view by a user of device  10 . 
     If desired, via structures may be used to reduce or eliminate the need for ledge  82  on thin-film-transistor layer  58 . An illustrative configuration for display  14  in which the width of the inactive border for the display has been minimized by eliminating thin-film-transistor ledge  82  is shown in  FIG. 9 . As shown in  FIG. 9 , vias  112  may be formed between the upper and lower surfaces of thin-film-transistor layer  58 . When routing signals through thin-film-transistor layer  58  in this way, ledge  82  may be eliminated. 
     Vias  112 , which may sometimes be referred to as via structures, metal vias, or through vias, may be used to connect conductive lines in thin-film-transistor circuitry  106  such as conductive lines  96  to the circuitry of flexible printed circuit  64  (e.g., to conductive lines in flexible printed circuit such as conductive lines  100 ). Vias  112  may include holes that pass through substrate  108  and metal or other conductive material that fully or partly fills the holes. Solder, conductive adhesive, or other conductive materials may be used to couple the metal of vias  112  to the metal of conductive lines  100  in flexible printed circuit  64 . Solder or other conductive materials may also be used in mounting driver circuitry such as display driver integrated circuit  62  to traces  100  of flexible printed circuit  64 . 
     Flexible printed circuit  64  may include one or more bends such as right-angle bend  114  of  FIG. 9 . With the illustrative configuration of  FIG. 9 , flexible printed circuit  64  may have a portion that lies flat on the lower surface of substrate  108  and a portion that extends away from substrate  108  at a perpendicular angle (e.g., vertically downward in the arrangement of  FIG. 9 ). This type of arrangement may allow display driver integrated circuit  62  to be mounted along the inner surface of a housing sidewall in housing  12  of device  10 . 
     Vias  112  may be formed by drilling openings in thin-film-transistor substrate  108  (e.g., using laser etching or other hole formation techniques). Following the formation of openings in thin-film-transistor layer substrate  108 , metal or other conductive material may be formed within the openings (e.g., using physical vapor deposition, chemical vapor deposition, electrochemical deposition, or other suitable fabrication techniques). If desired, vias  112  may be formed by embedding metal wires within thin-film-transistor layer  108  during glass formation operations. 
     As shown in  FIG. 10 , display driver integrated circuit  62  may be mounted directly to the lower surface of thin-film-transistor substrate layer  108 . Solder, conductive adhesive, or other conductive material may be used in interconnecting the circuitry of display driver integrated circuit  62  to the metal of vias  112 . Metal pads may be formed on the lower surface of substrate  108  (e.g., on vias  112  or connected to vias  112 ) and/or on display driver integrated circuit  62 . Solder, conductive adhesive, or other conductive material may be interposed between the metal pads on substrate  108  and on display driver integrated circuit  62 . 
     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: 20120831
Publication Date: 20160927
Grant Date: 20160927
Priority Date: 20120831
Inventors: ZHONG JOHN Z.
CHEN CHENG
CHANG SHIH-CHANG
YIN VICTOR H.
GETTEMY SHAWN R.
CHEN WEI
Assignee: APPLE INC
CPC Classifications: [{"code": "H10D86/411", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10D86/60", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/13452", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F2201/42", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/13306", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/13452", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/044", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0412", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/044", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F2201/42", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/1368", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/13", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/133528", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/13306", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F2201/42", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09F9/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/13338", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/13452", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L25/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/133514", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K59/1213", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K59/40", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K50/86", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K59/124", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K59/131", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K59/8791", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K59/8791", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 50187112