PATENT DOCUMENT

Publication Number: US-11309370-B1
Application Number: US-201916239413-A
Country: US
Kind Code: B1

Title: Electronic device displays with curved surfaces

Abstract:
A plurality of fibers may be included in an electronic device display to allow the display to have a curved output surface. Each fiber may guide light from one or more display pixels on the display panel to a display output surface. The fibers may be bent, allowing light from the display pixels to be displayed on a three-dimensional display output surface of any desired shape. The fibers may be formed from a high refractive index core surrounded by a cladding. The fibers may be formed from an activated photoactive material. The fibers may cover the entire display panel, the periphery of the display panel, or the corners of the display panel. The display panel may have one or more bends. Polarizing fibers may be used to both guide light from the display panel and serve as a linear polarizer for the display.

Claims:
What is claimed is: 
     
       1. An electronic device comprising:
 a display panel that displays an image; 
 a display cover layer that covers the display panel; and 
 fibers interposed between the display panel and the display cover layer that overlap a corner portion of the display panel, wherein the fibers receive a portion of the image from the display panel and present the portion of the image at an output surface of the fibers that has compound curvature in a rounded corner that is bent downwards towards the display panel. 
 
     
     
       2. The electronic device defined in  claim 1 , wherein each fiber comprises a cladding that surrounds a core that has a higher index of refraction than the cladding. 
     
     
       3. The electronic device defined in  claim 2 , further comprising:
 filler material that fills space between the fibers. 
 
     
     
       4. The electronic device defined in  claim 1 , wherein the display panel comprises a flexible display panel with a bent portion. 
     
     
       5. The electronic device defined in  claim 4 , wherein the fibers overlap pixels in the bent portion of the flexible display panel. 
     
     
       6. The electronic device defined in  claim 5 , wherein the fibers also overlap pixels in a central planar portion of the flexible display panel. 
     
     
       7. The electronic device defined in  claim 1 , wherein the fibers have an input surface adjacent to the display panel and wherein the fibers guide light from the input surface to the output surface. 
     
     
       8. An electronic device comprising:
 a display panel that emits light; 
 four discrete fiber bundles, wherein each fiber bundle overlaps a respective corner portion of the display panel and wherein the display panel has edge portions that are not covered by any fibers; and 
 a display cover layer formed over the fiber bundles, wherein each fiber bundle comprises fibers that guide the light from the display panel to an interior surface of the display cover layer. 
 
     
     
       9. The electronic device defined in  claim 8 , wherein the interior surface of the display cover layer is a curved interior surface. 
     
     
       10. The electronic device defined in  claim 9 , wherein each fiber bundle has an output surface that conforms to the curved interior surface of the display cover layer. 
     
     
       11. The electronic device defined in  claim 8 , wherein each fiber bundle has an input surface that receives the light from the display panel and conveys the light from the input surface to an output surface. 
     
     
       12. The electronic device defined in  claim 8 , wherein each fiber comprises a cladding that surrounds a core with a higher index of refraction than the cladding. 
     
     
       13. The electronic device defined in  claim 12 , wherein each fiber bundle has a filler material that fills space between the fibers in that fiber bundle. 
     
     
       14. The electronic device defined in  claim 12 , wherein each fiber bundle is attached between the display panel and a respective flexible substrate. 
     
     
       15. The electronic device defined in  claim 14 , wherein each flexible substrate is attached to the interior surface of the display cover layer. 
     
     
       16. The electronic device defined in  claim 8 , wherein each fiber comprises an activated photoactive material. 
     
     
       17. The electronic device defined in  claim 8 , wherein each fiber is a polarizing fiber that serves as a linear polarizer. 
     
     
       18. An electronic device comprising:
 a display cover layer with first and second opposing edges that couple to third and fourth opposing edges to form four corner regions; and 
 a display panel that is covered by the display cover layer, wherein the display panel has a planar central portion, a first display panel extension that extends from the planar central portion along the first edge and that is bent relative to the planar central portion, and a second display panel extension that extends from the first display panel extension into one of the four corner regions, and wherein the planar central portion, the first display panel extension, and the second display panel extension include pixels. 
 
     
     
       19. The electronic device defined in  claim 18 , wherein the first display panel extension has a planar portion and a bent portion and wherein the bent portion of the first display panel extension is interposed between the planar central portion of the display panel and the planar portion of the first display panel extension. 
     
     
       20. The electronic device defined in  claim 19 , wherein the second display panel extension extends from the planar portion of the first display panel extension and is bent relative to the planar portion of the first display panel extension, wherein the first display panel extension is bent relative to the planar central portion about a first axis and wherein the second display panel extension is bent relative to the planar portion of the first display panel extension about a second axis that is different than the first axis. 
     
     
       21. The electronic device defined in  claim 18 , wherein the planar central portion, first display panel extension, and second display panel extension form part of an active area of the display panel. 
     
     
       22. A method of forming a plurality of fibers that are configured to guide light from display pixels in a display panel to a curved interior surface of a display cover layer in an electronic device, the method comprising:
 forming a layer of photoactive material; and 
 with at least one light source, activating portions of the photoactive material, wherein each activated portion of the photoactive material forms a respective fiber of the plurality of fibers. 
 
     
     
       23. The method defined in  claim 22 , wherein activating the portions of the photoactive material with the at least one light source comprises using a single laser to emit a beam of light through the photoactive material to form each respective fiber of the plurality of fibers. 
     
     
       24. The method defined in  claim 22 , wherein activating the portions of the photoactive material with the at least one light source comprises using first and second lasers to emit respective first and second beams of light through the photoactive material to form each respective fiber of the plurality of fibers and wherein only portions of the photoactive material that are exposed to both the first and second beams of light are activated. 
     
     
       25. The method defined in  claim 22 , further comprising:
 after activating the portions of the photoactive material, removing remaining portions of the photoactive material; and 
 after removing the remaining portions of the photoactive material, adding a filler material between the plurality of fibers. 
 
     
     
       26. The method defined in  claim 22 , wherein forming the layer of photoactive material comprises forming the layer of photoactive material between the display panel and the display cover layer. 
     
     
       27. The method defined in  claim 22 , wherein forming the layer of photoactive material comprises forming the layer of photoactive material over the display panel. 
     
     
       28. The method defined in  claim 22 , wherein forming the layer of photoactive material comprises forming the layer of photoactive material below the display cover layer. 
     
     
       29. The method defined in  claim 22 , wherein forming the layer of photoactive material comprises forming a photopolymer. 
     
     
       30. The method defined in  claim 22 , wherein forming the layer of photoactive material comprises forming a chalcogenide glass. 
     
     
       31. An electronic device comprising:
 an array of organic light-emitting diode pixels; and 
 a circular polarizer that overlaps the array of organic light-emitting diode pixels, wherein the circular polarizer includes a linear polarizer formed from a plurality of polarizing fibers that guide light from the array of organic light-emitting diode pixels towards a display output surface. 
 
     
     
       32. The electronic device defined in  claim 31 , further comprising:
 an opaque display cover layer with a plurality of openings, wherein each polarizing fiber of the plurality of polarizing fibers protrudes into an opening of the plurality of openings. 
 
     
     
       33. An electronic device comprising:
 a display panel that displays an image; and 
 fibers that overlap a corner portion of the display panel, wherein the fibers receive a portion of the image from the display panel and present the portion of the image at an output surface of the fibers that has compound curvature in a rounded corner that is bent downwards. 
 
     
     
       34. The electronic device defined in  claim 33 , wherein each fiber comprises a cladding that surrounds a core and wherein the core has a higher index of refraction than the cladding. 
     
     
       35. The electronic device defined in  claim 33 , wherein the fibers have an input surface adjacent to the display panel and wherein the fibers guide light from the input surface to the output surface. 
     
     
       36. An electronic device comprising:
 a display panel that displays an image; and 
 fibers that overlap a corner portion of the display panel, wherein the fibers receive a portion of the image from the display panel and present the portion of the image at an output surface of the fibers that has compound curvature in a corner that is bent. 
 
     
     
       37. An electronic device comprising:
 a display panel that emits light; 
 four discrete fiber bundles, wherein each fiber bundle overlaps a respective corner portion of the display panel and wherein the display panel has edge portions that are not covered by any fibers.

Description:
This application claims priority to U.S. provisional patent application No. 62/616,676 filed Jan. 12, 2018, 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, an electronic device may have an organic light-emitting diode display based on organic-light-emitting diode pixels or a liquid crystal display based on liquid crystal pixels. In some cases, it may be desirable for a display to have a curved display surface. However, it may be difficult to curve conventional organic light-emitting diode displays and liquid crystal displays to have the desired curved display surface. 
     It would therefore be desirable to be able to provide improved displays for electronic devices. 
     SUMMARY 
     An electronic device may have a display such as an organic light-emitting diode display or a liquid crystal display. To allow the display to have a curved output surface, the display may include a plurality of fibers. 
     Each fiber may guide light from one or more display pixels on the display panel to a display output surface. The fibers may be bent, allowing light from the display pixels to be displayed on a three-dimensional display output surface of any desired shape. The fibers may be formed from a high refractive index core surrounded by a cladding. The fibers may be attached to a flexible substrate that is then attached to an electronic device component such as the interior surface of the display cover layer. 
     The fibers may also be formed by activating a photoactive material using one or more light sources. One light source may be used to form a plurality of linear fibers in the photoactive material, or two or more light sources may be used to form non-linear fibers in the photoactive material. The light source for activating the photoactive material may be a laser that emits visible or ultraviolet light. 
     The fibers may cover any desired portion of the underlying display panel. For example, the fibers may cover the entire display panel, the periphery of the display panel, or the corners of the display panel. The display panel may also have one or more bends to help form the desired display output surface. 
     Organic light-emitting diode displays and liquid crystal displays may include a linear polarizer layer. To reduce the thickness of the display and the distance between the display plane and the display output surface, polarizing fibers may be used to both guide light from the display panel and serve as the linear polarizer. In some embodiments, the polarizing fibers may extend into openings of the display cover layer such that the ends of the fibers form an outermost surface of the electronic device. This allows the display cover layer to be an opaque material such as a metal or a ceramic. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an illustrative electronic device having a display in accordance with an embodiment. 
         FIG. 2  is a schematic diagram of an illustrative display in accordance with an embodiment. 
         FIG. 3  is a cross-sectional side view of an illustrative liquid crystal display in accordance with an embodiment. 
         FIG. 4  is a cross-sectional side view of an illustrative organic light-emitting diode display in accordance with an embodiment. 
         FIG. 5  shows cross-sectional side views of steps for forming a fiber relay in accordance with an embodiment. 
         FIG. 6  is a cross-sectional side view of an illustrative electronic device with a fiber relay between a display panel and a flexible substrate in accordance with an embodiment. 
         FIG. 7  is a flowchart of illustrative method steps for forming a fiber relay between a display panel and a display cover layer in accordance with an embodiment. 
         FIG. 8  shows cross-sectional side views of steps for forming a fiber using a photoactive material and a single light source in accordance with an embodiment. 
         FIG. 9  shows cross-sectional side views of steps for forming a fiber using a photoactive material and two or more light sources in accordance with an embodiment. 
         FIG. 10  is a flowchart of illustrative method steps for using photoactive material to form a fiber relay between a display panel and a display cover layer in accordance with an embodiment. 
         FIGS. 11A-11C  are top views of illustrative displays showing how fibers may be used to guide light from different portions of the displays in accordance with an embodiment. 
         FIG. 12  is a top view of an illustrative display panel that is bent in accordance with an embodiment. 
         FIG. 13  is a cross-sectional side view of an illustrative electronic device with a bent display panel and a fiber relay in accordance with an embodiment. 
         FIG. 14  is a top view of an illustrative display panel with multiple bends in accordance with an embodiment. 
         FIG. 15  is a perspective view of the illustrative display panel of  FIG. 14  after the display panel has been bent in accordance with an embodiment. 
         FIG. 16  is a cross-sectional side view of an illustrative electronic device with fibers between a linear polarizer and a display cover layer in accordance with an embodiment. 
         FIG. 17  is a cross-sectional side view of an illustrative electronic device with polarizing fibers that replace the function of a linear polarizer in accordance with an embodiment. 
         FIG. 18  is a cross-sectional side view of an illustrative electronic device with polarizing fibers that form an outermost surface of the electronic device in accordance with an embodiment. 
         FIG. 19  is a cross-sectional side view of an illustrative electronic device with fibers that protrude into openings in the display cover layer to form an outermost surface of the electronic device in accordance with an embodiment. 
     
    
    
     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 display, a computer display that contains an embedded computer, 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, or other electronic equipment. Electronic device  10  may have the shape of a pair of eyeglasses (e.g., supporting frames), may form a housing having a helmet shape, or may have other configurations to help in mounting and securing the components of one or more displays on the head or near the eye of a user. 
     As shown in the example of  FIG. 1 , device  10  may have a housing such as housing  12 . Housing  12  may be formed from plastic, metal (e.g., aluminum), fiber composites such as carbon fiber, glass, ceramic, other materials, and combinations of these materials. Housing  12  or parts of housing  12  may be formed using a unibody construction in which housing structures are formed from an integrated piece of material. Multipart housing constructions may also be used in which housing  12  or parts of housing  12  are formed from frame structures, housing walls, and other components that are attached to each other using fasteners, adhesive, and other attachment mechanisms. Glass structures, transparent polymer structures, image transport layer structures, and/or other transparent structures that cover display  14  and other portions of device  10  may provide structural support for device  10  and may sometimes be referred to as housing structures. For example, a glass or polymer layer that covers and protects a pixel array in display  14  may serve as a display cover layer while also serving as a housing structure for device  10 . 
     As shown in  FIG. 1 , electronic device  10  may include control circuitry  18  for supporting the operation of device  10 . The control 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  18  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  16  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  16  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  16  and may receive status information and other output from device  10  using the output resources of input-output devices  16 . 
     Input-output devices  16  may include one or more displays such as display  14 . Display  14  may be a touch screen display that includes a touch sensor for gathering touch input from a user or display  14  may be insensitive to touch. A touch sensor for display  14  may be based on an array of capacitive touch sensor electrodes, acoustic touch sensor structures, resistive touch components, force-based touch sensor structures, a light-based touch sensor, or other suitable touch sensor arrangements. A touch sensor for display  14  may be formed from electrodes formed on a common display substrate with the pixels of display  14  or may be formed from a separate touch sensor panel that overlaps the pixels of display  14 . If desired, display  14  may be insensitive to touch (i.e., the touch sensor may be omitted). 
     Control circuitry  18  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  18  may display images on display  14 . 
       FIG. 2  is a diagram of an illustrative display. As shown in  FIG. 2 , display  14  may include layers such as substrate layer  26 . Substrate layers such as layer  26  may be formed from rectangular planar layers of material or layers of material with other shapes (e.g., circular shapes or other shapes with one or more curved and/or straight edges). The substrate layers of display  14  may include glass layers, polymer layers, composite films that include polymer and inorganic materials, metallic foils, etc. 
     Display  14  may have an array of pixels  22  for displaying images for a user such as pixel array  28 . Pixels  22  in array  28  may be arranged in rows and columns. The edges of array  28  may be straight or curved (i.e., each row of pixels  22  and/or each column of pixels  22  in array  28  may have the same length or may have a different length). There may be any suitable number of rows and columns in array  28  (e.g., ten or more, one hundred or more, or one thousand or more, etc.). Display  14  may include pixels  22  of different colors. As an example, display  14  may include red pixels, green pixels, and blue pixels. If desired, a backlight unit may provide backlight illumination for display  14 . 
     Display driver circuitry  20  may be used to control the operation of pixels  28 . Display driver circuitry  20  may be formed from integrated circuits, thin-film transistor circuits, and/or other suitable circuitry. Illustrative display driver circuitry  20  of  FIG. 2  includes display driver circuitry  20 A and additional display driver circuitry such as gate driver circuitry  20 B. Gate driver circuitry  20 B may be formed along one or more edges of display  14 . For example, gate driver circuitry  20 B may be arranged along the left and right sides of display  14  as shown in  FIG. 2 . 
     As shown in  FIG. 2 , display driver circuitry  20 A (e.g., one or more display driver integrated circuits, thin-film transistor circuitry, etc.) may contain communications circuitry for communicating with system control circuitry over signal path  24 . Path  24  may be formed from traces on a flexible printed circuit or other cable. The control circuitry may be located on one or more printed circuits in electronic device  10 . During operation, control circuitry (e.g., control circuitry  18  of  FIG. 1 ) may supply circuitry such as a display driver integrated circuit in circuitry  20  with image data for images to be displayed on display  14 . Display driver circuitry  20 A of  FIG. 2  is located at the top of display  14 . This is merely illustrative. Display driver circuitry  20 A may be located at both the top and bottom of display  14  or in other portions of device  10 . 
     To display the images on pixels  22 , display driver circuitry  20 A may supply corresponding image data to data lines D while issuing control signals to supporting display driver circuitry such as gate driver circuitry  20 B over signal paths  30 . With the illustrative arrangement of  FIG. 2 , data lines D run vertically through display  14  and are associated with respective columns of pixels  22 . 
     Gate driver circuitry  20 B (sometimes referred to as gate line driver circuitry or horizontal control signal circuitry) may be implemented using one or more integrated circuits and/or may be implemented using thin-film transistor circuitry on substrate  26 . Horizontal control lines G (sometimes referred to as gate lines, scan lines, emission control lines, etc.) run horizontally through display  14 . Each gate line G may be associated with a respective row of pixels  22 . If desired, there may be multiple horizontal control lines such as gate lines G associated with each row of pixels. Individually controlled and/or global signal paths in display  14  may also be used to distribute other signals (e.g., power supply signals, etc.). 
     Gate driver circuitry  20 B may assert control signals on the gate lines G in display  14 . For example, gate driver circuitry  20 B may receive clock signals and other control signals from circuitry  20 A on paths  30  and may, in response to the received signals, assert a gate line signal on gate lines G in sequence, starting with the gate line signal G in the first row of pixels  22  in array  28 . As each gate line is asserted, data from data lines D may be loaded into a corresponding row of pixels. In this way, control circuitry such as display driver circuitry  20 A and  20 B may provide pixels  22  with signals that direct pixels  22  to display a desired image on display  14 . Each pixel  22  may have a light-emitting diode and circuitry (e.g., thin-film circuitry on substrate  26 ) that responds to the control and data signals from display driver circuitry  20 . 
     Gate driver circuitry  20 B may include blocks of gate driver circuitry such as gate driver row blocks. Each gate driver row block may include circuitry such output buffers and other output driver circuitry, register circuits (e.g., registers that can be chained together to form a shift register), and signal lines, power lines, and other interconnects. Each gate driver row block may supply one or more gate signals to one or more respective gate lines in a corresponding row of the pixels of the array of pixels in the active area of display  14 . 
     Display  14  may be a liquid crystal display or an organic light-emitting diode display, as examples.  FIG. 3  is a cross-sectional side view of an illustrative liquid crystal display for device  10 . As shown in  FIG. 3 , 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. 3 ) and passes through pixels in display layers  46 . This illuminates any images that are being produced by the 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 sometimes collectively be referred to as a display panel. 
     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. 
     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 (inner) polarizer layer  60  and upper (outer) polarizer layer  54 . 
     Layers  58  and  56  may be formed from transparent substrate layers such as clear layers of glass or plastic. Layers  58  and  56  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 pixel circuits based on thin-film transistors and associated electrodes (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. Configurations in which color filter elements are combined with thin-film transistor structures on a common substrate layer in the upper or lower portion of display  14  may also be used. 
     During operation of display  14  in device  10 , control circuitry (e.g., one or more integrated circuits on a printed circuit) may be used to generate information to be displayed on display  14  (e.g., display data). The information to be displayed may be conveyed to a display driver integrated circuit such as circuit  62 A or  62 B using a signal path such as a signal path formed from conductive metal traces in a rigid or flexible printed circuit such as printed circuit  64  (as an example). 
     Backlight structures  42  may include a light guide layer such as light guide layer  78 . Light guide layer  78  may be formed from a transparent material such as clear glass or plastic (e.g., molded plastic that forms a light guide plate, a thin flexible plastic film, etc.). 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 in dimensions X and Y throughout light guide layer  78  due to the principal of total internal reflection. Light guide layer  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 layer  78 . Light source  72  may be located at the left of light guide layer  78  as shown in  FIG. 3  or may be located along the right edge of layer  78  and/or other edges of layer  78 . 
     Light  74  that scatters upwards in direction Z from light guide layer  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 plastic covered with a dielectric mirror thin-film coating. 
     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 light collimating films such as brightness enhancement films and turning films. Optical films  70  may overlap the other structures in backlight unit  42  such as light guide layer  78  and reflector  80 . For example, if light guide layer  78  has a rectangular footprint in the X-Y plane of  FIG. 3 , optical films  70  and reflector  80  may have a matching rectangular footprint. If desired, films such as compensation films may be incorporated into other layers of display  14  (e.g., polarizer layers). 
     Display  14  may include one or more additional layers such as layer  82  on top of polarizer  54 . For example, layers such as layer  82  may include a wave plate or other optical film to adjust the polarization of the light exiting display  14 . 
       FIG. 4  is a cross-sectional side view of an illustrative organic light-emitting diode display for use in device  10 . As shown in  FIG. 4 , display  14  may include a substrate layer such as substrate layer  90 . Substrate  90  may be formed from a polymer or other suitable materials. Thin-film transistor circuitry  92  may be formed on substrate  90 . Thin film transistor circuitry  92  may include inorganic layers such as inorganic buffer layers, barrier layers (e.g., barrier layers to block moisture and impurities), gate insulator, passivation, interlayer dielectric, and other inorganic dielectric layers. Thin-film transistor circuitry  92  may also include organic dielectric layers such as a polymer planarization layer. Metal layers and semiconductor layers may be included within thin-film transistor circuitry  92  to form transistors and light-emitting diodes. 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. Metal may be used in forming transistor gate terminals, transistor source-drain terminals, capacitor electrodes, and metal interconnects. 
     Light-emitting diodes  94  may be formed from the patterned layers of material in thin-film transistor circuitry  92  and may serve as pixels for display  14 . In each light-emitting diode, organic emissive material and other light-emitting diode layers may be interposed between a respective anode and cathode. During operation, light-emitting diodes  94  may emit light  96  for forming images for viewing by viewer  48 . Layers such as layers  98  and  100  may be formed on top of thin-film transistor circuitry  92 . Layer  100  may be a circular polarizer for suppressing ambient light reflections from metal structures and other reflective structures in thin-film transistor circuitry  92 . Circular polarizer  100  may include a linear polarizer and a quarter-wave plate. Optional layer  98  may be a wave plate or other optical film for adjusting the polarization of emitted light  96 . Wave plates in device  10  may be formed from single-layer structures or multi-layer structures to provide broadband transmission spectrums and wide viewing angles. The organic light-emitting diode display structures shown in  FIG. 4  may sometimes be referred to as a display panel. 
     In some cases, it may be desirable for display  14  to have a curved display surface. To form a curved display surface, display  14  may optionally be bent. However, display  14  may only tolerate bending in one direction (e.g., along one bending axis). Therefore, to allow a display surface to be curved in two directions (or to avoid any bending of display  14 ), the display may include a fiber relay (sometimes referred to as a group of fibers). The fiber relay may include a plurality of fibers that guide light from the display panel to the desired display output surface. The fibers may be flexible, enabling the display output surface to have any desired three-dimensional shape. For example, the display output surface may be curved in two directions, otherwise known as having compound curvature. When bent along only one direction, the display output surface may be flattened into a plane without distortion (sometimes referred to as developable surfaces). When bent along two directions, the display output surface has compound curvature (e.g., a surface that can only be flattened into a plane with distortion, sometimes referred to as a surface with Gaussian curvature). 
       FIG. 5  shows a cross-sectional side view of the formation of an illustrative fiber relay (sometimes referred to as a fiber bundle) for use in an electronic device display. As shown in  FIG. 5 , at step  302  a plurality of fibers may be encased in a host matrix material. Fiber relay  142  may include a plurality of fibers  144  that are surrounded by host matrix material  146 . Each fiber  144  may include a core  148  that is surrounded by cladding  150 . The cores may be formed from a clear material such as glass, polymer, etc. The index of refraction of the core may be greater than the index of refraction of the cladding to promote total internal reflection. Host matrix material  146  may be any desired material and may maintain the structural integrity of fiber relay  142 . If desired, cladding  150  may be omitted from each fiber  144 . 
     At step  304 , fiber relay  142  may be attached between two substrates. As shown, a first end of each fiber  144  in fiber relay  142  may be attached to substrate  152  whereas a second opposing end of each fiber  144  in fiber relay  142  may be attached to substrate  154 . Substrates  152  and  154  may be any desired layer or material. Substrate  152  may be a flexible substrate that can later be bent to form a desired display surface. Substrate  152  may sometimes be referred to as elastomeric and may be formed from any desired material (e.g., rubber, silicone, etc.). In one illustrative example, substrate  154  may be a display layer (e.g., a layer of display  14 ). For example, substrate  154  may be an upper polarizer (e.g., upper polarizer  54 ), a thin-film transistor layer (e.g., thin-film transistor layer  58 ), a color filter layer (e.g., color filter layer  56 ) or a wave plate or other optical film (e.g., additional layer  82 ) of a liquid crystal display (e.g., the liquid crystal display in  FIG. 3 ). As yet other examples, substrate  154  may be a layer of thin-film transistor circuitry (e.g., thin-film transistor circuitry  92 ), a circular polarizer (e.g., circular polarizer  100 ) or a wave plate or other optical film (e.g., additional layer  98 ) of an organic light-emitting diode display (e.g., the organic light-emitting diode display in  FIG. 4 ). 
     At step  306  host matrix material  146  may be removed from fiber relay  142 . When the host matrix material  146  is removed, the remaining fibers  144  are free to bend into any desired shape. Therefore, if fiber relay  142  is attached to a display structure, the fiber relay allows light from display  14  to be mapped to the surface of any desired three-dimensional shape (e.g., an output surface having compound curvature). 
       FIG. 6  is a cross-sectional side view of an illustrative electronic device with a fiber relay of the type shown in  FIG. 5 . As shown, fiber relay  142  may include fibers  144 , with each fiber having a core surrounded by a cladding. One end of each fiber may be attached to display panel  160  (e.g., display panel  160  may serve as substrate  154  from  FIG. 5 ). The other end of each fiber may be attached to flexible substrate  152 . The flexible substrate  152  may then in turn be attached to an interior surface of display cover layer  162 . Display cover layer  162  may be a layer of clear glass, plastic, or other dielectric that covers the light-emitting surface of the underlying display panel. In another suitable arrangement, display cover layer  162  may be the outermost layer of display  14  (e.g., layer  162  may be a color filter layer, thin-film transistor layer, or other display layer). Buttons may pass through openings in cover layer  162 . The cover layer may also have other openings such as an opening for a speaker port, openings for a sensor, or openings for any other desired electronic component. 
     As shown in  FIG. 6 , fiber relay  142  may be used to direct light from a planar edge portion of the display panel to a curved output surface. Because fibers  144  and substrate  152  are flexible, the light may be directed to an output surface of any desired shape. The flexible substrate may be attached to the interior surface of display cover layer  162  with adhesive (e.g., transparent adhesive). 
     The example in  FIG. 6  of fiber relay  142  being used to direct light from the display panel to a display cover layer is merely illustrative. In general, fiber relay  142  may direct light from the display panel to any desired display output surface. For example, the fiber relay may be attached to the electronic device housing (e.g., housing  12  in  FIG. 1 ) or another device component (instead of the display cover layer). 
     If desired, a filler material  164  may be formed in between fibers  144  of fiber relay  142  after flexible substrate  152  is attached to display cover layer  162 . Filler material  164  may conform to the shape of the fibers to fill any voids between the fibers. This may help maintain the structural integrity of the fibers and keep the fibers in a desired position. Filler material  164  may be any desired material. 
     Each fiber  144  may be aligned with one pixel in display  14 . Alternatively, each pixel may be overlapped by multiple fibers. In yet another embodiment, each fiber may overlap multiple pixels. In general, each pixel may be overlapped by any desired number of pixels (e.g., exactly one, more than one, less than one, etc.). Different pixels may also be overlapped by different numbers of fibers. 
     Each fiber  144  in  FIG. 6  has a uniform cross-section across the length of the fiber. This example is merely illustrative. If desired, the cross-section of the fiber may change along the length of the fiber. For example, the cross-section of the fiber may progressively increase in surface area moving from the display panel to the display cover layer. In this way, the light from the display panel can be magnified onto a larger area on the display cover layer. 
       FIG. 7  is a flowchart of illustrative method steps for forming a fiber relay that maps output from a display panel to an arbitrary three-dimensional shape. As shown, at step  402  fibers that are encased in a host matrix material may be attached between a display panel (e.g., any layer in a display) and a flexible substrate. Once attached to the flexible substrate and display panel, the host matrix material may be removed at step  404 . Once the host matrix material is removed, the fibers may be free to flex into any desired position based on the position of the flexible substrate. At step  406 , the flexible substrate may be attached to a display cover layer (or other desired electronic device component such as a housing). The flexible substrate may be attached to a curved interior surface of a transparent display cover layer (as shown in  FIG. 6 ), for example. Optionally, an additional filler material may be formed around the fibers of the fiber relay once the fiber relay is attached between the display panel and the display cover layer. 
     The example in  FIGS. 5-7  of the fiber relay being formed from a plurality of fibers (each with a high refractive index core surrounded by cladding) initially encased in a host matrix material is merely illustrative. In another embodiment, fibers may be formed by activating a photoactive material using controlled exposure to light. 
       FIG. 8  is a cross-sectional side view of an illustrative electronic device during formation of a fiber using a photoactive material. As shown in  FIG. 8 , at step  502  a photoactive material  170  is formed between display panel  160  and display cover layer  162 . Photoactive material  170  may undergo a chemical or physical change in response to exposure to a particular type of light. There are many types of photoactive materials that may be used. In one example, photoactive material  170  may be a photopolymer. Polymerization of the material may be initiated by exposure to light. For example, photoactive material  170  may initially be formed entirely of monomers. The portions of photoactive material  170  that are then exposed to light will polymerize to become polymers. In another embodiment, photoactive material  170  may be a chalcogenide glass. When exposed to light, the exposed portions of the chalcogenide glass may have a higher index of refraction than portions that are not exposed to the light, forming light guiding channels. 
       FIG. 8  shows an embodiment where a single light source is used to activate photoactive material  170 . As shown, light source  172  emits a beam of light  174  through photoactive material  170 . Light source  172  may emit any desired type of light that activates photoactive material  170 . For example, light source  172  may emit visible light, ultraviolet light, or infrared light. Light source  172  may be a laser or another desired type of light source. 
     At step  502  when light source  172  emits beam  174  through photoactive material  170 , region  176  of photoactive material  170  is activated by the light. As shown in  FIG. 8  at step  504 , this results in the formation of a channel  178 . Channel  178  may be a portion of photoactive material  170  that has been activated to form a fiber for a fiber relay. Channel  178  may have a high refractive index that allows the channel to guide light from display panel  160  to display cover layer  162  (or another desired electronic device structure). Multiple channels may be formed using photoactive material  170  to form a fiber relay. Each channel may form a respective fiber for the fiber relay. Each fiber may be aligned with exactly one pixel in display  14 , multiple pixels in display  14 , or a portion of a pixel in display  14 . 
     Using a single light source to activate photoactive material  170  may result in each fiber having a linear structure (e.g., each fiber extends along a single axis). Multiple light sources may instead by used to produce fibers with any desired three-dimensional structure. In this technique, multiple light sources may emit beams through photoactive material  170 . However, only portions of photoactive material  170  that are exposed to both light sources will be activated. This enables the activated portion to be precisely controlled in three-dimensions through the photoactive material. 
       FIG. 9  shows an embodiment where multiple light sources are used to activate photoactive material  170 . As shown, light source  172 A emits a beam of light  174 A through photoactive material  170  and light source  172 B emits a beam of light  174 B through photoactive material  170 . Light sources  172 A and  172 B may emit any desired type of light that activates photoactive material  170  (e.g., visible light, ultraviolet light, infrared light etc.). Light sources  172 A and  172 B may be lasers or other desired types of light sources. 
     At step  602  when light source  172 A emits beam  174 A through photoactive material  170  and light source  172 B emits beam  174 B through photoactive material  170 , region  176  of photoactive material  170  that is exposed to both beams  174 A and  174 B may be activated. As shown in  FIG. 9  at step  604 , this intersection point between the beams may be moved in any direction in three-dimensions to form a channel  178  with any desired shape. Channel  178  is the portion of photoactive material  170  that has been activated to form a fiber for the fiber relay. Due to being activated by the light exposure, channel  178  may have a high refractive index that allows the channel to guide light from display panel  160  to display cover layer  162  (or another desired electronic device structure). Multiple channels may be formed in this way using photoactive material  170  to form a fiber relay. Each channel may form a fiber for the fiber relay. Each fiber may be aligned with exactly one pixel in display  14 , multiple pixels in display  14 , or a portion of a pixel in display  14 . 
       FIG. 10  is a flowchart of illustrative method steps for forming a fiber relay using a photoactive material. As shown in  FIG. 10 , at step  702  the photoactive material may be positioned between the two substrates of interest (or positioned above one substrate, with the additional substrate to be added after activation). For example, when the fiber relay is used to relay light from a display panel to a curved display output surface, the photoactive material may be positioned between the display panel and the display cover layer. Next, at step  704 , one or more light sources may be used to activate the photoactive material and form one or more fibers for the fiber relay. Portions of the photoactive material that are exposed to light from the one or more light sources may be activated and form a channel that guides light from the display panel to the display cover layer. One light source may be used to form a plurality of linear fibers or multiple light sources may be used to form fibers with non-linear shapes. Once all of the fibers have been formed in the photoactive material, the remaining photoactive material may optionally be exposed to a capping agent that reduces the reactivity of the photoactive material. 
     If desired, the portions of the photoactive material that were not activated in step  704  may remain between the display panel and the display cover layer. These remaining portions may act as a host matrix that help maintain the shape of the fibers. Alternatively, the portions of the photoactive material that were not activated in step  704  may optionally be removed at step  706 . If the portions of the photoactive material that were not activated in step  704  are removed at step  706 , an additional filler material may optionally be added at step  708 . The additional filler material may conform to the shape of the fibers and fill any voids between the fibers. This may help maintain the structural integrity of the fibers and keep the fibers in a desired position. Any desired material may be used as the additional filler material in step  708 . 
     As previously discussed, fiber relays may use a plurality of fibers to guide light from a display panel to a display output surface. The fiber relay may be used to cover (and guide light from) any desired portion of the display panel.  FIGS. 11A-11C  are top views showing various arrangements with at least a portion of the display panel covered by fibers. 
       FIG. 11A  shows an illustrative display  14  where the entire display panel is covered by fiber relay  142 . In other words, every pixel may emit light into one or more fibers that then guide the emitted light to a display output surface. The display output surface may have any desired shape. In some embodiments, a central portion of the display output surface may be planar while a peripheral portion of the display output surface may be curved. The corner portions of the display output surface may have compound curvature, for example. In the central portion of the fiber relay, fibers may guide light straight up from the central portion of the display panel to the display output surface (without any curvature). Fibers that overlap the peripheral portions of the display, however, may be bent in order to guide light to the curved edges of the display output surface. 
     In another embodiment, shown in  FIG. 11B , only a portion of the display panel may be covered by fibers. In the example of  FIG. 11B , the peripheral portion of the display panel is covered by fiber relay  142  whereas the central portion of the display panel is not covered by fiber relay  142 . In this type of arrangement, a central portion of the display output surface may be planar (because light is being emitted from the central portion of the display without modification by the fibers). An edge portion of the display output surface, however, may use the fiber relay  142  to have any desired three-dimensional shape. For example, the fiber relay may be used to create a curved edge for the display output surface around the entire periphery of the display. The display output surface may have compound curvature in each of the four corners of the display and may have curvature along a single axis along the edges that extend between the four corners. This example of the entire periphery of the display output surface having a curved edge is merely illustrative. If desired, only one edge, only two edges, or only three edges of the display output surface may be curved using the fiber relay. 
     In yet another embodiment, shown in  FIG. 11C , only the corners of the display panel are covered by fibers. The display may have a rectangular shape with an upper left corner, an upper right corner, a lower left corner, and a lower right corner. The corners may optionally be rounded corners. A first fiber relay  142 A is formed over a first corner (e.g., an upper-left corner) of the display panel, a second fiber relay  142 B is formed over a second corner (e.g., an upper-right corner) of the display panel, a third fiber relay  142 C is formed over a third corner (e.g., a lower-left corner) of the display panel, and a fourth fiber relay  142 D is formed over a fourth corner (e.g., a lower-right corner) of the display panel. Edge portions of the display panel that run between the corners, as well as a central portion of the display panel, are not covered by fibers. In this type of arrangement, a central portion of the display output surface (e.g., non-corner portions) may be planar (because light is being emitted from the central portion of the display without modification by the fibers). The corners of the display output surface, however, may use the fiber relays to have any desired three-dimensional shape (e.g., compound curvature). This example of the four corners of the display output surface being curved is merely illustrative. If desired, only one corner, only two corners, or only three corners of the display output surface may be curved using the fiber relay. 
     Forming fiber relays in the corners of the display may be particularly helpful given the limitations of bending the display panel itself. To help form a curved display output surface, the display panel may be bent. This may result in the display output surface being curved (even without the use of a fiber relay). However, the display panel may only be able to accommodate bends along a single axis at a time. Thus, forming a display output surface with certain three-dimensional shapes may still be difficult. Forming fiber relays in the corner of the display may enable the display output surface to have multiple bends (e.g., a rounded corner that is bent downwards). The display output surface may therefore use the four discrete fiber relays of  FIG. 11C  to have compound curvature in the corners. 
       FIG. 12  is a top view of an illustrative display panel that is bent to form a curved display output surface.  FIG. 12  depicts display panel  160  in an unbent state (e.g., before the extensions of the display panel have been bent). As shown, display panel  160  (which may sometimes be referred to as a display active area that includes display pixels) may include display panel extensions (sometimes referred to as display panel tabs, bent regions, or bent portions of the display panel)  160 - 1 ,  160 - 2 ,  160 - 3 , and  160 - 4 . Each display panel extension is configured to be bent along a respective bend axis. Display panel extension  160 - 1  is configured to be bent along bend axis  182 - 1 , display panel extension  160 - 2  is configured to be bent along bend axis  182 - 2 , display panel extension  160 - 3  is configured to be bent along bend axis  182 - 3 , and display panel extension  160 - 4  is configured to be bent along bend axis  182 - 4 . Bend axes  182 - 1  and  182 - 4  may be parallel and bend axes  182 - 2  and  182 - 3  may be parallel. Bend axis  182 - 1  may be perpendicular to bend axes  182 - 2  and  182 - 3 . The display panel extensions may surround a central portion  160 - 5  of the display panel that is not bent. 
     By bending the display panel as shown in  FIG. 12 , the periphery of the display output surface may be curved (as the display panel includes display pixels on the central portion and the display panel extensions). This example of the display panel having four display panel extensions (around the entire periphery of the display) that are bent is merely illustrative. If desired, the display panel may have only one display panel extension that is bent, only two display panel extensions that are bent, or only three display panel extensions that are bent. In all of these embodiments, any desired portion(s) of the display panel may be covered by fibers. The fibers may be used to further curve the display output surface (e.g., to have compound curvature), for example. 
       FIG. 13  is a cross-sectional side view of an illustrative electronic device with a bent display panel (e.g., the display panel of  FIG. 12 ) and a fiber relay. As shown, display panel extension  160 - 3  is bent around bend axis  182 - 3  relative to central display panel portion  160 - 5 . This helps promote a curved display output surface (e.g., display output surface  184 ). The display in  FIG. 13  also includes fiber relay  142 . Fiber relay  142  includes fibers  144  that guide light from display panel  160  to display cover layer  162 . The fibers may enable further curvature of the display output surface if desired. Bending the display panel as shown in  FIG. 13  may minimize the relay distance required by fiber relay  142  (which may improve the display performance). 
     The display panel may have additional extensions to accommodate desired curved display output surfaces while still only bending the display panel along a single bend axis at a time.  FIG. 14  is a top view of an illustrative display panel that is bent to form a curved display output surface.  FIG. 14  depicts display panel  160  in an unbent state (e.g., before the extensions of the display panel have been bent). As shown, display panel  160  may have display panel extensions  160 - 3  and  160 - 4  bent along axes  182 - 3  and  182 - 4  respectively (similar to as discussed in connection with  FIG. 12 ). It may be desirable to make additional bends to display panel extension  160 - 3  (e.g., to further reduce the relay distance of a fiber relay that will overlap the corner of the display panel). However, as discussed previously each portion of the display panel can only be bent in one direction. Therefore, once display panel extension  160 - 3  is bent along axis  182 - 3 , a planar portion of display panel extension  160 - 3  may be bent along axis  182 - 5 . 
     When display panel extension  160 - 3  in  FIG. 14  is bent downwards (e.g., into the page), portion  186  may be bent. The curvature of the bend may start at bend axis  182 - 3  and be limited to region  186  of the display panel extension. The remaining portion  188  of the display panel extension may be planar (even after the extension is bent along axis  182 - 3 ). The remaining portion  188  of the display panel extension may, for example, be positioned in the YZ-plane after the extension is bent in region  186 . This planar portion  188  may have an extended portion  190  that is then bent along bend axis  182 - 5 . The extended portion  190  of the display panel may be used to form a rounded corner shape for the display. 
       FIG. 15  is a perspective view of the display panel of  FIG. 14  after the display panel has been bent. As shown in  FIG. 15 , the central portion  160 - 5  of the display panel lies parallel to the XY-plane. The display panel extension  160 - 4  is bent downwards (e.g., in the negative Z-direction) along bend axis  182 - 4  (which is parallel to the X-axis). Display panel extension  160 - 3  is bent downwards in region  186  along axis  182 - 3  (which is parallel to the Y-axis). Finally, extension  190  of planar portion  188  is bent along axis  182 - 5  into a rounded corner shape. The display panel may include display pixels on all of the display panel portions shown in  FIG. 15 . Therefore, even though extension  190  is only bent once (thus satisfying the reliability requirements for the display panel), the display panel can approximate a display output surface with a rounded corner that is bent downwards (i.e., the display panel can approximate a display output surface with compound curvature). 
     Liquid crystal displays, organic light-emitting diode displays, and other types of displays that may be used to form the display panel may include a linear polarizer layer. For example, the liquid crystal display (LCD) in  FIG. 3  includes an upper polarizer  54  and the organic light-emitting diode (OLED) display in  FIG. 4  includes a circular polarizer  100  (that includes a linear polarizer). In these cases, the polarizer layer must be interposed between the display layer (e.g., the light-emitting diodes of an OLED display or the liquid crystal layer of an LCD display) and the outer surface of the electronic device. An arrangement of this type is shown in  FIG. 16 . 
       FIG. 16  is a cross-sectional side view of an electronic device with a display, a linear polarizer, and a fiber relay. As shown in  FIG. 16 , linear polarizer  192  may be formed over display layers of the display (e.g., display panel  160 ). Fibers  142  are then formed over the linear polarizer and interposed between the linear polarizer and the display cover layer  162 . In this arrangement, the display plane (e.g., display panel  160 ) is spatially separated from the outer surface of the electronic device (e.g., the outer surface of display cover layer  162 ), which can be aesthetically undesirable. 
     To minimize the distance between the display plane and the outer surface of the electronic device, polarizing fibers may be used in fiber relay  142 . The linear polarizer can therefore be eliminated from the stack-up, moving the display plane closer to the outer surface of the electronic device (for improved aesthetics) and reducing the thickness of the display. An arrangement of this type is shown in  FIG. 17 . As shown, fiber relay  142  includes polarizing fibers that will replace the function of the linear polarizer  192  from  FIG. 16 . 
     Polarizing fibers  142  in  FIG. 17  may have a structure similar to those shown in  FIG. 5  (e.g., with each fiber having a core surrounded by a cladding and a host matrix material between each fiber). The polarizing functionality may be achieved by adding a chiral dopant to the core of the fibers. In the polarized fibers, light of the desired polarization will be guided through the fiber. In contrast, light of the undesired polarization will be ejected out of the core and into the host matrix material. The host matrix material may be blackened to prevent light leakage if desired. 
     If the display of  FIG. 17  is a liquid crystal display, polarizing fibers  142  may take the place of the upper polarizer of the liquid crystal display. For example, polarizing fibers  142  may be attached to transparent substrate  56  in  FIG. 3  without an intervening linear polarizer layer. The polarizing fibers may be the only linear polarizer that is interposed between the liquid crystal layer of the liquid crystal display and the outer surface of the electronic device. If the display of  FIG. 17  is an organic light-emitting diode display, polarizing fibers  142  may take the place of the linear polarizer in the circular polarizer of the liquid crystal display. For example, polarizing fibers  142  may be attached to thin-film transistor circuitry  92  in  FIG. 4  without an intervening linear polarizer layer. The circular polarizer for the organic light-emitting diode display may still require a quarter wave plate. The polarizing fibers may be attached to a quarter wave plate for the circular polarizer without an intervening linear polarizer layer. The polarizing fibers may be the only linear polarizer that is interposed between the light-emitting diodes of the organic light-emitting diode display and the outer surface of the electronic device. 
     The polarizing fibers in polarizing fiber relay  142  may have any desired length (e.g., less than 10 millimeters, less than 1 millimeter, less than 100 microns, less than 10 microns, greater than 1 micron, greater than 10 microns, greater than 100 microns etc.). The polarizing fibers may cover any desired portion of the display panel (e.g., the entire display panel as shown in  FIG. 11A , the edges of the display panel as shown in  FIG. 11B , or the corners of the display panel as shown in  FIG. 11C ) and the display panel may have any desired number of bends. 
       FIG. 18  is a cross-sectional side view of an illustrative embodiment where the polarizing fibers form an outer surface of the electronic device. In this arrangement, no display cover layer may be formed over the polarizing fibers, allowing the display plane to appear to be on the outer surface of the electronic device. This type of arrangement allows for the possibility of opaque materials covering the display, as shown in  FIG. 19 . 
       FIG. 19  is a cross-sectional side view of an electronic device with a display cover layer  162  that may be non-transparent (e.g., opaque). As shown in  FIG. 19 , display cover layer  162  has a number of openings  192  that receive fibers  144  of fiber relay  142 . Fibers  144  may guide light directly from the display panel  160  to the outermost surface of the electronic device (e.g., surface  184 ). The fibers  144  and display cover layer  162  may combine to form the outermost surface of the electronic device. Display cover layer  162  may be formed from an opaque material in this embodiment. For example, display cover layer  162  may be metal, ceramic, or another opaque material. 
       FIG. 19  shows one fiber formed in each opening of display cover layer  162 . This example is merely illustrative. If desired, more than one fiber may be formed in each opening of display cover layer  162 . The openings of the display cover layer may be formed and then the fibers may be inserted into the openings. Alternatively, the display cover layer may be grown or molded around the fibers such that the fibers are embedded in the display cover layer. 
     As shown in  FIG. 19 , a filler material  164  may be formed in between fibers  144  of fiber relay  142 . Filler material  164  may conform to the shape of the fibers to fill any voids between the fibers. This may help maintain the structural integrity of the fibers and keep the fibers in a desired position. Filler material  164  may be any desired material. Filler material  164  may be opaque or transparent. In some embodiments, display cover layer  162  may be omitted and filler material  164  may be the only component maintaining the structure of the fibers. In this scenario, filler material  164  may also form a portion of the outermost surface of the electronic device. 
     Fibers of the type shown in  FIG. 19  may cover any desired portion of the display panel (e.g., the entire display panel as shown in  FIG. 11A , the edges of the display panel as shown in  FIG. 11B , or the corners of the display panel as shown in  FIG. 11C ) and the display panel may have any desired number of bends. 
     In various embodiments, an electronic device may include a display panel having first and second opposing edges that couple to third and fourth opposing edges to form four corners, a plurality of groups of fibers that are each aligned with a respective corner of the display panel, and a display cover layer formed over the plurality of groups of fibers. Each group of fibers may include a plurality of fibers that guide light from the display panel to a curved interior surface of the display cover layer. 
     Each fiber of the plurality of fibers of each group of fibers may include a cladding that surrounds a core with a higher index of refraction than the cladding. Each group of fibers may have a filler material that fills space between the plurality of fibers in that group of fibers. Each group of fibers may be attached between the display panel and a respective flexible substrate. Each flexible substrate may be attached to the curved interior surface of the display panel. Each fiber of the plurality of fibers of each group of fibers may include an activated photoactive material. Each fiber of the plurality of fibers of each group of fibers may be a polarizing fiber that serves as a linear polarizer. The display panel may have a planar central portion and a first display panel extension and the first display panel extension may run along the first edge of the display panel and may be bent around a first bend axis relative to the planar central portion of the display panel. The first display panel extension may have a curved portion and a planar portion and the planar portion may have an additional extension that is bent around a second bend axis. 
     In various embodiments, an electronic device may include display structures having an array of display pixels and a plurality of polarizing fibers formed on the display structures that guide light from the array of display pixels towards a display surface. The display structures may include liquid crystal display structures, the liquid crystal display structures may include a lower linear polarizer and a liquid crystal layer, and the plurality of polarizing fibers may serve as an upper linear polarizer for the liquid crystal display structures. The display structures may include organic light-emitting diode structures, the organic light-emitting diode structures may include a circular polarizer, and the plurality of polarizing fibers may serve as a linear polarizer for the circular polarizer. The electronic device may also include an opaque display cover layer with a plurality of openings and each polarizing fiber of the plurality of polarizing fibers may protrude into an opening of the plurality of openings. 
     In various embodiments, a method of forming a plurality of fibers between a display panel and a display cover layer in an electronic device includes forming a photoactive material between the display panel and the display cover layer and activating portions of the photoactive material to form the plurality of fibers with at least one light source. Each fiber of the plurality of fibers may guide light from at least one display pixel of the display panel to a curved interior surface of the display cover layer. 
     Activating the portions of the photoactive material to form the plurality of fibers with the at least one light source may include using a single laser to emit a beam of light through the photoactive material to form each fiber of the plurality of fibers. Activating the portions of the photoactive material to form the plurality of fibers with the at least one light source may include using first and second lasers to emit respective first and second beams of light through the photoactive material to form each fiber of the plurality of fibers. Only portions of the photoactive material that are exposed to both the first and second beams of light may be activated. The method may also include removing remaining portions of the photoactive material after activating the portions of the photoactive material to form the plurality of fibers. The method may also include adding a filler material between the plurality of fibers after removing the remaining portions of the photoactive material. Forming the photoactive material between the display panel and the display cover layer may include forming a photopolymer between the display panel and the display cover layer. Forming the photoactive material between the display panel and the display cover layer may include forming a chalcogenide glass between the display panel and the display cover layer. 
     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: 20190103
Publication Date: 20220419
Grant Date: 20220419
Priority Date: 20180112
Inventors: BROWN, MICHAEL J.
QIAO, YI
KAKUDA, TYLER R.
SOYSEVEN, ALEXIS G.
GUILLOU, Jean-Pierre S.
Assignee: APPLE INC
CPC Classifications: [{"code": "G02F1/133331", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/118", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/133528", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/133305", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L51/5293", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/133528", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L51/5287", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/133305", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L27/3244", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01L2251/5338", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/118", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K2102/311", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/133524", "inventive": true, "first": true, "tree": "[]"}, {"code": "H10K59/12", "inventive": true, "first": true, "tree": "[]"}, {"code": "H10K50/182", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K50/868", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K2102/311", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K59/12", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K59/875", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K59/8791", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K59/8793", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 81187205