PATENT DOCUMENT

Publication Number: US-9614168-B2
Application Number: US-201614987129-A
Country: US
Kind Code: B2

Title: Flexible display panel with bent substrate

Abstract:
A display may have an array of organic light-emitting diodes that form an active area on a flexible substrate. Metal traces may extend between the active area and an inactive area of the flexible substrate. Display driver circuitry such as a display driver integrated circuit may be coupled to the inactive area. The metal traces may extend across a bend region in the flexible substrate. The flexible substrate may be bent in the bend region. The flexible substrate may be made of a thin flexible material to reduce metal trace bending stress. A coating layer in the bend region may be provided with an enhanced elasticity to allow its thickness to be reduced. The flexible substrate may be bent on itself and secured within an electronic device without using a mandrel.

Claims:
What is claimed is: 
     
       1. A display, comprising:
 a flexible substrate; 
 an array of pixels that form an active area on the flexible substrate; 
 metal traces that extend from the active area to an inactive area on the flexible substrate across a bend region on the flexible substrate, wherein the flexible substrate is folded over against itself at the bend region so that the active area overlaps the inactive area, wherein the inactive area defines a plane parallel to the active area; 
 first and second polymer layers interposed between the active area and the inactive area that is overlapped by the active area; and 
 first, second, and third adhesive layers, wherein the first adhesive layer is interposed between the first polymer layer and the active area of the flexible substrate and attaches the first polymer layer to the active area of the flexible substrate, wherein the second adhesive layer is interposed between the second polymer layer and the inactive area of the flexible substrate and attaches the second polymer layer to the inactive area of the flexible substrate, wherein the third adhesive layer is interposed between the first and second polymer layers and attaches the first and second polymer layers together, wherein the first, second, and third adhesive layers have aligned edges that are separated from the bent region of the flexible substrate by a gap, and wherein the first and second polymer layers and the first, second, and third adhesive layers are the only layers interposed between the active area of the flexible substrate and the plane defined by the inactive area of the flexible substrate. 
 
     
     
       2. The display defined in  claim 1  wherein the flexible substrate is a polyimide substrate with a thickness of less than 16 microns. 
     
     
       3. The display defined in  claim 1  wherein the flexible substrate is a polyimide substrate with an elasticity of less than 5 GPa. 
     
     
       4. The display defined in  claim 1  wherein the flexible substrate is coated with a coating layer in the bend region that has an elasticity of more than 0.7 GPa. 
     
     
       5. The display defined in  claim 4  wherein the flexible substrate is a polyimide substrate. 
     
     
       6. The display defined in  claim 5  wherein the flexible substrate has a thickness of less than 16 microns. 
     
     
       7. The display defined in  claim 1  wherein the first and second polymer layers have respective first and second edges at the bend region that are aligned with each other. 
     
     
       8. The display defined in  claim 1  wherein the first and second polymer layers have respective first and second edges and, and wherein the respective first and second edges of the polymer layers are aligned with the aligned edges of the first, second, and third adhesive layers. 
     
     
       9. The display defined in  claim 1  wherein the first and second polymer layers have respective first and second edges at the bend region that are not aligned with each other. 
     
     
       10. The display defined in  claim 1  wherein the array of pixels comprises an array of organic light-emitting diode pixels. 
     
     
       11. A display, comprising:
 a flexible substrate having opposing first and second surfaces; 
 an array of pixels that form an active area on the first surface of the flexible substrate, wherein the flexible substrate is folded at a bend region; 
 first and second polymer layers that are attached between a first portion of the second surface of the flexible substrate and a second portion of the second surface of the flexible substrate; 
 a first layer of adhesive between the first and second polymer layers, the first layer of adhesive having a first edge; and 
 a second layer of adhesive between the second polymer layer and the second portion of the second surface of the flexible substrate, the second layer of adhesive having a second edge aligned with the first edge. 
 
     
     
       12. The display defined in  claim 11  further comprising metal traces that extend from the active area to an inactive area on the flexible substrate across the bend region, wherein the inactive area is free of pixels. 
     
     
       13. The display defined in  claim 12  wherein the first layer of adhesive has a protruding portion that protrudes from between the first and second polymer layers and that contacts the flexible substrate. 
     
     
       14. The display defined in  claim 11  wherein the array of pixels comprises an array of organic light-emitting diode pixels. 
     
     
       15. The display defined in  claim 14  wherein the flexible substrate is coated with a coating layer in the bend region. 
     
     
       16. The display defined in  claim 11 , further comprising:
 a third layer of adhesive between the first polymer layer and the first portion of the second surface of the flexible substrate, wherein the third layer of adhesive has a third edge aligned with the first edge and with the second edge. 
 
     
     
       17. An organic light-emitting diode display, comprising:
 thin-film transistor circuitry that forms an array of pixels; 
 a flexible substrate having a first surface on which the thin-film transistor circuitry is formed and having an opposing second surface, wherein the flexible substrate is bent back on itself in a bend region so that a first portion of the second surface faces a second portion of the second surface; 
 at least one polymer layer and at least one layer of adhesive that attach the first portion to the second portion; and 
 a polymer coating on the first surface of the flexible substrate, wherein the polymer coating overlaps a portion of the thin-film transistor circuitry so that the thin-film transistor circuitry is interposed between the polymer coating and the first surface, wherein the polymer coating is bent back on itself in the bend region and extends behind the first and second portions of the second surface of the flexible substrate to overlap the array of display pixels, the at least one polymer layer, and the at least one layer of adhesive. 
 
     
     
       18. The organic light-emitting diode display defined in  claim 17  wherein the at least one polymer layer comprises first and second polymer layers, and wherein the at least one layer of adhesive includes adhesive between the first and second polymer layers that attaches the first polymer layer to the second polymer layer. 
     
     
       19. The organic light-emitting diode display defined in  claim 17  further comprising:
 a moisture barrier film that overlaps the thin-film transistor circuitry, wherein the polymer coating overlaps the moisture barrier film so that the moisture barrier film and the thin-film transistor circuitry are interposed between the polymer coating and the first surface. 
 
     
     
       20. An apparatus, comprising:
 a flexible substrate; 
 an array of pixels on the flexible substrate that form an active area of the flexible substrate, wherein the active area has a rectangular shape that is surrounded by an inactive area; 
 metal traces that extend from the active area to the inactive area on the flexible substrate across a bend region on the flexible substrate, wherein the flexible substrate is folded over against itself at the bend region so that the active area overlaps the inactive area; 
 first and second polymer layers interposed between the active area and the inactive area that is overlapped by the active area; and 
 first, second, and third adhesive layers, wherein the first adhesive layer is interposed between the first polymer layer and the active area of the flexible substrate and attaches the first polymer layer to the active area of the flexible substrate, wherein the second adhesive layer is interposed between the second polymer layer and the inactive area of the flexible substrate and attaches the second polymer layer to the inactive area of the flexible substrate, wherein the third adhesive layer is interposed between the first and second polymer layers and attaches the first and second polymer layers together, and wherein the inactive area of the flexible substrate overlaps at least half of the active area of the flexible substrate. 
 
     
     
       21. The apparatus defined in  claim 20  wherein the flexible substrate is a polyimide substrate with a thickness of less than 16 microns. 
     
     
       22. The apparatus defined in  claim 20  wherein the flexible substrate is a polyimide substrate with an elasticity of less than 5 GPa. 
     
     
       23. The apparatus defined in  claim 20  wherein the flexible substrate is coated with a coating layer in the bend region that has an elasticity of more than 0.7 GPa. 
     
     
       24. The apparatus defined in  claim 20  wherein the flexible substrate is a polymer substrate. 
     
     
       25. The apparatus defined in  claim 20  wherein the flexible substrate is a polymer substrate, the apparatus further comprising:
 an array of sensor structures in the active area. 
 
     
     
       26. The apparatus defined in  claim 20  wherein the first and second polymer layers have respective first and second edges and wherein the third adhesive layer has a protruding portion that extends from between the first and second polymer layers past the first and second edges. 
     
     
       27. The apparatus defined in  claim 20 , wherein the first and second polymer layers overlap at least half of the active area of the flexible substrate. 
     
     
       28. The apparatus defined in  claim 27 , wherein the first, second, and third adhesive layers overlap at least half of the active area of the flexible substrate.

Description:
This application claims the benefit of provisional patent application No. 62/102,284, filed Jan. 12, 2015, which is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     This relates generally to electronic devices with displays, and, more particularly, to displays with bent portions. 
     Electronic devices often include displays. Displays such as organic light-emitting diode displays may be formed on flexible substrates. Displays with flexible substrates may be bent. For example, it may be desirable to bend an edge of a display to hide inactive display components along the edge of the display from view. 
     The process of bending a display can create stresses within the structures of the display. For example, bent metal traces may become stressed. Stress-induced damage such as cracks may adversely affect display reliability. 
     It would therefore be desirable to be able to provide improved displays with bent portions. 
     SUMMARY 
     A display may have an array of organic light-emitting diodes that form an active area on a flexible substrate. Metal traces may extend between the active area and an inactive area of the flexible substrate. Display driver circuitry such as a display driver integrated circuit may be coupled to the inactive area. The metal traces may extend across a bend region in the flexible substrate. The flexible substrate may be bent in the bend region. 
     The flexible substrate may be made of a thin flexible material to reduce metal trace bending stress. A coating layer in the bend region may be provided with an enhanced elasticity to allow its thickness to be reduced. The flexible substrate may be bent on itself and secured within an electronic device without using a mandrel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device having a display in accordance with an embodiment. 
         FIG. 2  is a schematic diagram of an illustrative electronic device having a display in accordance with an embodiment. 
         FIG. 3  is a top view of an illustrative display in an electronic device in accordance with an embodiment. 
         FIG. 4  is a cross-sectional side view of a portion of an illustrative organic light-emitting diode display in accordance with an embodiment. 
         FIG. 5  is perspective view of an illustrative display with a bent portion in accordance with an embodiment. 
         FIG. 6  is a cross-sectional side view of an illustrative display with a bent portion in accordance with an embodiment. 
         FIG. 7  is a cross-sectional side view of an illustrative bent substrate showing how a neutral stress plane may be aligned with metal traces on the substrate using a coating layer in accordance with an embodiment. 
         FIG. 8  is a cross-sectional side view of an illustrative display having a flexible substrate with a coating layer that has been bent in accordance with an embodiment. 
         FIG. 9  is a cross-sectional side view of an illustrative display with a bent flexible substrate in accordance with an embodiment. 
         FIGS. 10, 11, and 12  are cross-sectional side views of illustrative layers in displays with bent flexible substrates in accordance with embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     An illustrative electronic device of the type that may be provided with a display is shown in  FIG. 1 . Electronic device  10  may be a computing device such as a laptop computer, a computer monitor containing an embedded computer, a tablet computer, a cellular telephone, a media player, or other handheld or portable electronic device, a smaller device such as a wrist-watch device, a pendant device, a headphone or earpiece device, a device embedded in eyeglasses or other equipment worn on a user&#39;s head, or other wearable or miniature device, a television, a computer display that does not contain an embedded computer, a gaming device, a navigation device, an embedded system such as a system in which electronic equipment with a display is mounted in a kiosk or automobile, equipment that implements the functionality of two or more of these devices, or other electronic equipment. In the illustrative configuration of  FIG. 1 , device  10  is a portable device such as a cellular telephone, media player, tablet computer, wrist device, or other portable computing device. Other configurations may be used for device  10  if desired. The example of  FIG. 1  is merely illustrative. 
     In the example of  FIG. 1 , device  10  includes a display such as display  14  mounted in housing  12 . Housing  12 , which may sometimes be referred to as an enclosure or case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of any two or more of these materials. Housing  12  may be formed using a unibody configuration in which some or all of housing  12  is machined or molded as a single structure or may be formed using multiple structures (e.g., an internal frame structure, one or more structures that form exterior housing surfaces, etc.). 
     Display  14  may be a touch screen display that incorporates a layer of conductive capacitive touch sensor electrodes or other touch sensor components (e.g., resistive touch sensor components, acoustic touch sensor components, force-based touch sensor components, light-based touch sensor components, etc.) or may be a display that is not touch-sensitive. Capacitive touch screen electrodes may be formed from an array of indium tin oxide pads or other transparent conductive structures. 
     Display  14  may include an array of display pixels formed from liquid crystal display (LCD) components, an array of electrophoretic display pixels, an array of plasma display pixels, microelectromechanical (MEMS) shutter pixels, electrowetting pixels, micro-light-emitting diodes (small crystalline semiconductor die), organic light-emitting diodes (e.g., a thin-film organic light-emitting diode display), quantum dot light-emitting diodes, or display pixels based on other display technologies. The array of display pixels may display images for a user in active area of display  14 . The active area may be surrounded on one or more sides by inactive border regions. 
     Display  14  may be protected using a display cover layer such as a layer of transparent glass or clear plastic. Openings may be formed in the display cover layer. For example, an opening may be formed in the display cover layer to accommodate a button, a speaker port, or other component. Openings may be formed in housing  12  to form communications ports (e.g., an audio jack port, a digital data port, etc.), to form openings for buttons, etc. 
       FIG. 2  is a schematic diagram of device  10 . As shown in  FIG. 2 , electronic device  10  may have control circuitry  16 . Control circuitry  16  may include storage and processing circuitry for supporting the operation of device  10 . The storage and processing circuitry may 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. Processing circuitry in control circuitry  16  may be used to control the operation of device  10 . The processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio chips, application specific integrated circuits, etc. 
     Input-output circuitry in device  10  such as input-output devices  18  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Input-output devices  18  may include buttons, joysticks, scrolling wheels, touch pads, key pads, keyboards, microphones, speakers, tone generators, vibrators, cameras, sensors, light-emitting diodes and other status indicators, data ports, etc. A user can control the operation of device  10  by supplying commands through input-output devices  18  and may receive status information and other output from device  10  using the output resources of input-output devices  18 . Input-output devices  18  may include one or more displays such as display  14 . 
     Control circuitry  16  may be used to run software on device  10  such as operating system code and applications. During operation of device  10 , the software running on control circuitry  16  may display images on display  14  using an array of pixels in display  14 . 
     Display  14  may have a rectangular shape (i.e., display  14  may have a rectangular footprint and a rectangular peripheral edge that runs around the rectangular footprint) or may have other suitable shapes. Display  14  may be planar or may have a curved profile. 
     A top view of a portion of display  14  is shown in  FIG. 3 . As shown in  FIG. 3 , display  14  may have an array of pixels  22 . Pixels  22  may receive data signals over signal paths such as data lines D and may receive one or more control signals over control signal paths such as horizontal control lines G (sometimes referred to as gate lines, scan lines, emission control lines, etc.). There may be any suitable number of rows and columns of pixels  22  in display  14  (e.g., tens or more, hundreds or more, or thousands or more). Each pixel  22  may have a light-emitting diode  26  that emits light  24  under the control of a pixel control circuit formed from thin-film transistor circuitry such as thin-film transistors  28  and thin-film capacitors). Thin-film transistors  28  may be polysilicon thin-film transistors, semiconducting-oxide thin-film transistors such as indium zinc gallium oxide transistors, or thin-film transistors formed from other semiconductors. 
     A cross-sectional side view of a portion of an illustrative organic light-emitting diode display in the vicinity of one of light-emitting diodes  26  is shown in  FIG. 4 . As shown in  FIG. 4 , display  14  may include a substrate layer such as substrate layer  30 . Substrate  30  may be formed from plastic or other suitable materials. Configurations for display  14  in which substrate  30  has been formed from a flexible material such as polyimide or other flexible polymer are sometimes described herein as an example. 
     Thin-film transistor circuitry  44  may be formed on substrate  30 . Thin film transistor circuitry  44  may include layers  32 . Layers  32  may include inorganic layers such as inorganic buffer layers, gate insulator, passivation, interlayer dielectric, and other inorganic dielectric layers. Layers  32  may also include organic dielectric layers such as a polymer planarization layer. Metal layers and semiconductor layers may also be included within layers  32 . For example, semiconductors such as silicon, semiconducting-oxide semiconductors, or other semiconductor materials may be used in forming semiconductor channel regions for thin-film transistors  28 . Metal in layers  32  may be used in forming transistor gate terminals, transistor source-drain terminals, capacitor electrodes, and metal interconnects. 
     As shown in  FIG. 4 , thin-film transistor circuitry  44  may include diode anode structures such as anode  36 . Anode  36  may be formed from a layer of conductive material such as metal on the surface of layers  32  (e.g., on the surface of a planarization layer that covers underlying thin-film transistor structures). Light-emitting diode  26  may be formed within an opening in pixel definition layer  40 . Pixel definition layer  40  may be formed from a patterned photoimageable polymer such as polyimide. In each light-emitting diode, organic emissive material  38  is interposed between a respective anode  36  and cathode  42 . Anodes  36  may be patterned from a layer of metal. Cathode  42  may be formed from a common conductive layer that is deposited on top of pixel definition layer  40 . Cathode  42  is transparent so that light  24  may exit light emitting diode  26 . During operation, light-emitting diode  26  may emit light  24 . 
     Metal interconnect structures may be used to interconnect transistors and other components in circuitry  44 . Metal interconnect lines may also be used to route signals to capacitors, to data lines D and gate lines G, to contact pads (e.g., contact pads coupled to gate driver circuitry), and to other circuitry in display  14 . As shown in  FIG. 4 , layers  32  may include one or more layers of patterned metal for forming interconnects such as metal traces  74 . 
     If desired, display  14  may have a protective outer display layer such as cover glass layer  70 . The outer display layer may be formed from a material such as sapphire, glass, plastic, clear ceramic, or other transparent material. Protective layer  46  may cover cathode  42 . Layer  46  may include moisture barrier structures, encapsulant materials, adhesive, and/or other materials to help protect thin-film transistor circuitry. Functional layers  68  may be interposed between layer  46  and cover layer  70 . Functional layers  68  may include a touch sensor layer, a circular polarizer layer, and other layers. A circular polarizer layer may help reduce light reflections from metal traces in thin-film transistor circuitry  44 . A touch sensor layer may be formed from an array of capacitive touch sensor electrodes on a flexible polymer substrate. The touch sensor layer may be used to gather touch input from the fingers of a user, from a stylus, or from other external objects. Layers of optically clear adhesive may be used to attach cover glass layer  70  and functional layers  68  to underlying display layers such as layer  46 , thin-film transistor circuitry  44 , and substrate  30 . 
     Display  14  may have an active area in which pixels  22  form images for viewing by a user of device  10 . The active area may have a rectangular shape. Inactive portions of display  14  may surround the active area. For example, signal traces and other support circuitry such as thin-film display driver circuitry may be formed along one or more of the four edges of display  14  that run around the rectangular periphery of display  14  adjacent to the active area. If desired, one or more display driver integrated circuits may be mounted to substrate  30  in the inactive border. For example, a flexible printed circuit on which one or more display driver integrated circuits have been mounted using solder may be attached to the border of display  14 . This type of configuration is sometimes referred to as a chip-on-flex configuration and allows display driver circuitry to supply signals to the data and gate lines on display  14 . 
     To minimize the amount of the inactive border area of display  14  that is visible to a user, one or more edges of display  14  may be bent. As an example, the edge of display  14  to which a display driver circuit is mounted using a chip-on-flex arrangement may be folded under the active area of display  14 . This helps minimize visible display borders and reduces the footprint of display  14 . 
     An illustrative display with a bent edge portion is shown in  FIG. 5 . As shown in  FIG. 5 , display  14  has portion  14 A (i.e., a planar active area portion that contains the active area of display  14  that is formed by an array of pixels  22 ), bent portion  14 B, and inactive portion  14 C. If desired, connectors, display driver integrated circuits or other integrated circuits, flexible printed circuits, and/or other components may be mounted to inactive portion  14 C of display  14 . 
     Metal traces  74  may carry signals between inactive area  14 C of display  14  and active area  14 A of display  14  (i.e., metal traces  74  may traverse bent portion  14 B of display  14 ). As shown in the cross-sectional side view of the illustrative display of  FIG. 6 , when bent portion  14 B is bent around bend axis  72 , portion  14 C is folded under portion  14 A and is therefore hidden from view by a user such as viewer  80  who is viewing display  14  in direction  82 . As shown in  FIG. 6 , components  76  (e.g., display driver circuitry, etc.) may be mounted on the upper and/or lower surface of display  14  in region  14 C. An optional support structure such as mandrel  78  may be used to support display  14  in bend region  14 B (e.g., to help establish a desired minimum bend radius in region  14 B) or, more preferably, mandrel  78  may be omitted to help minimize display thickness (e.g., by allowing portions  14 A and  14 C to be mounted more closely together and by allowing the bend radius for region  14 B to be reduced). 
     When bending display  14  in region  14 B, care should be taken to ensure that sensitive display structures do not become damaged. Stresses can be imparted to display structures in a flexible display when the display is bent. For example, metal traces such as metal traces  74  of  FIG. 5  that are used to form signal lines that convey signals between display driver circuitry or other circuits in inactive region  14 C and pixels  22  in region  14 A may be subjected to bending stresses in bend region  14 B. To minimize bending stress and thereby minimize cracks in metal traces  74 , it may be desirable to align the neutral stress plane of display  14  in bend region  14 B with metal traces  74 . 
     As shown in  FIG. 7 , when a portion of display  14  is bent in region  14 B, some layers such as substrate  30  may be subjected to compressive stress and some layers such as coating layer  84  may be subjected to tensile stress. Neutral stress plane  86  arises where stress has been eliminated by balancing the compressive stress and tensile stress. The shape of neutral stress plane  86  may be curved in a curved portion of display  14  such as portion  14 B of  FIG. 7  (i.e., neutral stress plane  86  may have a curved profile). 
     The relative thicknesses of substrate  30  and coating  84  and the relative modulus of elasticity values for substrate  30  and coating  84  determine the location of the neutral stress plane within the layers of bent display region  14 B. For example, if the elasticity of substrate  30  and coating  84  is the same, neutral stress plane  86  can be aligned with metal traces  74  by ensuring that coating  84  has the same thickness as substrate  30 . If, on the other hand, coating  84  has an elasticity that is larger than that of substrate  30 , coating  84  need not be as thick as substrate  30  to balance the compressive and tensile stresses. 
       FIG. 8  shows how coating  84  may be characterized by a thickness TB and elasticity E 2  and how substrate  30  may be characterized by a thickness TA and elasticity E 1 . The elasticity values E 1  and E 2  and the thickness values TA and TB may be selected to help ensure that region  14 B does not impart undesired stress to metal traces  74 . For example, thickness TA may be minimized (e.g., TA may be less than 16 microns, may be 5-15 microns, may be 8 microns, may be 6-12 microns, may be more than 5 microns, etc.) and substrate elasticity E 1  may be minimized (e.g., E 1  may be less than 9 GPa, may be less than 7 GPa, may be less than 5 GPa, may be 2-3 GPa, may be 1-5 GPa, or may be more than 0.5 GPa) to make flexible substrate  30  more flexible than would otherwise be possible. 
     The thickness TB and elasticity E 2  of coating  84  may be selected to balance the compressive stress produced when bending substrate  30 . With one suitable arrangement, the elasticity E 2  may be enhanced to help minimize the magnitude of thickness T 2  (and therefore reduce display thickness). The value of E 2  may be, for example, about 1 GPa, 0.7 to 1.3 GPa, more than 0.5 GPa, more than 0.7 GPa, more than 0.8 GPa, or less than 2 GPa (as examples). Substrate  30  may be, for example, polyimide and coating  84  may be, for example, a polymer adhesive that is thermally cured or that is cured by application of ultraviolet light. 
       FIG. 9  is a cross-sectional side view of an illustrative arrangement that may be used for bending display  14  (e.g., when it is desired to omit mandrel  78  of  FIG. 6 ). As shown in  FIG. 9 , display  14  may have active portion  14 A, bent portion  14 B, and inactive portion  14 C. In active portion  14 A, moisture barrier film  90  may cover the array of organic light-emitting diode pixels  22  and other thin-film transistor circuitry  44  to prevent moisture damage. Layers  68  may be interposed between cover layer  70  and moisture barrier layer  90 . Layers  68  may include polarizer  68 A (which may be attached to film  90  with pressure sensitive adhesive), optically clear adhesive layer  68 B, touch sensor  68 C, and optically clear adhesive  68 D (as an example). 
     In region  14 B, coating  84  may be used to adjust the location of the neutral stress plane in display  14  to avoid damage to metal traces  74 . 
     Portion  14 C may be bent under portion  14 A and may be secured to the underside of portion  14 A using layers such as layers  92  and  98 . Layer  92  may include a polymer layer such as polymer substrate layer  94  and a pressure sensitive adhesive layer such as layer  96  that attaches layer  94  to substrate  30 . Layer  98  may include a polymer layer such a polymer substrate  102  and a pressure sensitive adhesive layer such as layer  100  that attaches layer  102  to substrate  30 . Adhesive layer  96  may be interposed between layers  92  and  98  and may attach layer  94  to layer  102 , thereby attaching the folded portion of display  14  to itself. Layer  96  may be a foam adhesive, a layer of pressure sensitive adhesive, or other suitable adhesive. The thickness of layer  96  may be 30-250 microns, more than 25 microns, or less than 300 microns. The thickness of substrates  94  and  102  may be 100 microns, more than 50 microns, less than 150 microns, 70-130 microns, etc. The thickness of adhesive layers  96  and  100  may be 25 microns, more than 10 microns, less than 50 microns, etc. 
     Using an arrangement of the type shown in  FIG. 9 , display thickness can be minimized by allowing the display to be folded over against itself and attached together with adhesive (i.e., by allowing portion  14 C to be folded and secured against portion  14 A without use of a mandrel). 
       FIGS. 10, 11, and 12  are cross-sectional side views of additional configurations for the layers in displays with bent flexible substrates. 
     In the example of  FIG. 10 , layer  92  does not extend outwards as far as layer  98 , so ledge portion  98 L of layer  98  is exposed and the edges of layers  92  and  98  at the bent portion of display  14  are not aligned with each other. Arrangements of the type shown in  FIG. 10  may help bend portion  14 B of display  14  with a desired bend profile. 
     In the illustrative arrangement of  FIG. 11 , the edges of layers  98  and  92  (i.e., respective edge surfaces  98 E and  92 E) have been aligned with each other and have been aligned with edge surface (edge)  104 E of adhesive layer  104 . As with the arrangements of  FIGS. 9 and 10 , the use of this arrangement for layers  98  and  92  may be helpful in adjusting display  14  so that portion  14 B exhibits a desired bend profile. 
     In some situations, it may be desirable for edge  104 E of adhesive layer  104  to extend outwardly towards bent portion  14 B of display  14  past edges  92 E and  98 E of layers  92  and  98 . This type of arrangement is shown in  FIG. 12 . As shown in  FIG. 12 , adhesive layer  104  may protrude sufficiently far past edges  92 E and  98 E that edge surface  104 E of layer  104  contacts and supports inner surface  301  of substrate  30 . The use of a protruding adhesive layer such as layer  104  of  FIG. 12  may help ensure that bent display portion  14 B exhibits a desired bend profile. 
     Although sometimes described herein in the context of flexible displays, substrate  30  may be used to form any suitable devices. For example, circuitry may be formed on substrate  30  in regions  14 A,  14 B, and/or  14 C that forms one or more touch sensors that are free of pixels (i.e., pixels  22  may be replaced by touch sensor electrodes, packaged sensors, or other sensor structures), that forms force sensors, or that forms other electrical components with or without including pixels on substrate  30 . Thin-film circuitry and/or circuitry that forms part of a discrete device (e.g., integrated circuits etc.) may be formed on substrate  30  (e.g., in regions  14 A,  14 B, and/or  14 C) and may include sensors, integrated circuits with sensor circuitry or other sensor structures, input-output circuitry, control circuitry, or other circuitry. If desired, the circuitry on substrate  30  may allow some or all of substrate  30  to serve as a signal cable (e.g., a flexible printed circuit cable that contains signal lines for routing signals between different portions of device  10 ). In arrangements such as these, metal traces may extend across bent region  14 B to allow signal to pass between circuitry in regions  14 A and  14 C and, if desired, to route signals to and from circuitry in regions  14 B. The use of a portion of substrate  30  in forming a display is merely illustrative. 
     The foregoing is merely illustrative and various modifications can be made by those skilled in the art without departing from the scope and spirit of the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20160104
Publication Date: 20170404
Grant Date: 20170404
Priority Date: 20150112
Inventors: ZHANG ZHEN
TAO YI
DRZAIC PAUL S.
WURZEL JOSHUA G.
Assignee: APPLE INC
CPC Classifications: [{"code": "Y02E10/549", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L23/5387", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L23/4985", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L27/3276", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L2251/558", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L51/5253", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L23/5387", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L27/326", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L51/004", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L2251/5338", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L23/4985", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L51/0097", "inventive": true, "first": true, "tree": "[]"}, {"code": "Y02E10/549", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K59/121", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K85/141", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K77/111", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L23/5387", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K2102/351", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y02E10/549", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K2102/311", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K2102/351", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K85/141", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K50/844", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K59/131", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K59/121", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K2102/311", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K2102/311", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K77/111", "inventive": true, "first": true, "tree": "[]"}, {"code": "H10K59/122", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09F9/33", "inventive": true, "first": true, "tree": "[]"}, {"code": "H10K77/111", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01L23/4985", "inventive": true, "first": true, "tree": "[]"}, {"code": "H10K59/873", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K59/131", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K59/131", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K59/873", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K59/131", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K59/873", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 56368141