PATENT DOCUMENT

Publication Number: US-12181740-B1
Application Number: US-202318323906-A
Country: US
Kind Code: B1

Title: Curved devices

Abstract:
A transparent structure may have layers with curved cross-sectional profiles. The transparent structure may have inner and outer layers with curved portions formed by bending the layers. A display may be applied to one or more of the inner and outer layers. To reduce the strain applied to the display while being bent into a desired curvature, a carrier film may be used during bending operations. The carrier film may be modified with a patch or openings distribute the strain evenly across the display. Additionally or alternatively, a convex mold may be used to further decrease the strain on the display while being formed into the desired curvature.

Claims:
What is claimed is: 
     
       1. A window, comprising:
 a curved window layer; and 
 a display on the curved window layer, wherein the display is configured to operate in a first state and in a second state, the display transmits more visible light in the first state than in the second state, and the display has a maximum strain of 10% and a minimum strain of 0.5% across an entirety of the display. 
 
     
     
       2. The window defined in  claim 1 , wherein the curved window layer has a compound curvature and wherein the display comprises a liquid crystal device having a liquid crystal layer, the window further comprising:
 control circuitry that is configured to switch the liquid crystal layer from a transparent mode to a non-transparent mode to switch the display from the first state to the second state. 
 
     
     
       3. The window defined in  claim 2 , wherein the display has a maximum strain of 7% and a minimum strain of 1.5% across the entirety of the display. 
     
     
       4. The window defined in  claim 3 , wherein the display has a thickness of 200 microns or less across a surface of the curved window layer. 
     
     
       5. The window defined in  claim 1 , wherein the display has a maximum strain of 5% or less across the entirety of the display. 
     
     
       6. The window defined in  claim 1 , wherein the display is a liquid crystal device comprising a liquid crystal layer that is configured to be modulated to switch the display between the first state and the second state. 
     
     
       7. The window defined in  claim 1 , wherein the display comprises a display device selected from the group consisting of: an organic light-emitting diode display and a microLED display. 
     
     
       8. A method of forming a curved display, comprising:
 applying display layers to a carrier; 
 bending the carrier and the display layers in a convex mold; 
 modifying a region of the carrier to increase strain uniformity across the display layers; and 
 removing the display layers from the carrier. 
 
     
     
       9. The method defined in  claim 8 , wherein applying the display layers comprises applying the display layers to the carrier having a thickness of at least 125 microns. 
     
     
       10. The method defined in  claim 9 , wherein applying the display layers further comprises applying the display layers with a thickness of 200 microns or less. 
     
     
       11. The method defined in  claim 8 , wherein modifying the region of the carrier comprises applying a patch to the region of the carrier. 
     
     
       12. The method defined in  claim 11 , wherein applying the patch comprises applying the patch with a thickness of at least 75 microns. 
     
     
       13. The method defined in  claim 8 , wherein modifying the region of the carrier comprises forming openings in the carrier within the region. 
     
     
       14. The method defined in  claim 8 , wherein bending the carrier and the display layers in the convex mold comprises bending the carrier and the display layers on rounded edges of the convex mold. 
     
     
       15. The method defined in  claim 8 , further comprising:
 applying the display layers to a liner, wherein applying the display layers to the carrier comprises applying the display layers and the liner to the carrier. 
 
     
     
       16. A display, comprising:
 a curved display substrate having a first curvature; and 
 a display layer on the curved display substrate, wherein the display layer is curved with a second curvature that matches the first curvature, and the display layer has a maximum strain of 10% across an entirety of the display layer. 
 
     
     
       17. The display defined in  claim 16 , wherein the display layer has a minimum strain of 1.5% across the entirety of the display layer. 
     
     
       18. The display defined in  claim 17 , wherein the display layer has a thickness of at least 200 microns. 
     
     
       19. The display defined in  claim 16 , wherein the display layer is a layer selected from the group consisting of: an organic light-emitting diode display layer, a liquid crystal display layer, and a microLED display layer. 
     
     
       20. The display defined in  claim 19 , wherein the first curvature and the second curvature are compound curvatures. 
     
     
       21. The display defined in  claim 16 , wherein the display layer has a maximum strain of 5% across the entirety of the display layer. 
     
     
       22. The display defined in  claim 16 , wherein the display layer has a strain uniformity of at least 90%.

Description:
This application claims the benefit of provisional patent application No. 63/356,786, filed Jun. 29, 2022, which is hereby incorporated by reference herein in its entirety. 
    
    
     FIELD 
     This relates generally to electronic devices and, more particularly, to display devices. 
     BACKGROUND 
     Display devices may be used to display information and/or to modulate an amount of light that passes through a medium. It may be difficult to form curved display devices. 
     SUMMARY 
     A window in a system such as a vehicle or building may have window layers with curved cross-sectional profiles. For example, a vehicle window may have curved portions on left and right sides of the window. These curved portions may be formed by bending glass or other material into a desired shape. Window shaping operations may be performed by heating a planar glass layer or a layer of other material in window glass shaping equipment. 
     A window may have inner and outer layers. A display may be formed on one or more of the inner or outer layers. In particular, the display may be operable in a first state and a second state, and may transmit more light the first state than in the second state. In this way, light transmission through the window may be controlled by controlling the display. 
     To ensure that the display is not subject to an excessive amount of strain when applied to the curved window, a carrier layer may be used while the display is curved to reduce the amount of strain on the display. If desired, one or more portions of the carrier layer may be modified to distribute the strain uniformly across the display. 
     Alternatively or additionally, a convex mold may be used to further reduce the stress on the display as it is being formed with a desired curvature. In this way, a curved display device may be formed with an acceptable amount of strain. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a cross-sectional view of an illustrative system with a window in accordance with an embodiment. 
         FIG.  2    is a cross-sectional side view of a glass panel with a coating in accordance with an embodiment. 
         FIG.  3    is a perspective view of an illustrative glass panel in accordance with an embodiment. 
         FIGS.  4  and  5    are cross-sectional side views of the illustrative glass panel of  FIG.  3    in accordance with embodiments. 
         FIG.  6 A  is a side view of a mold and carrier used to form a curved display in accordance with an embodiment. 
         FIG.  6 B  is a side view of a mold, carrier, and liner used to form a curved display in accordance with an embodiment. 
         FIG.  7 A  is a graph of an illustrative relationship between cell thickness and cell strain in accordance with an embodiment. 
         FIG.  7 B  is a graph of an illustrative relationship between carrier thickness and cell strain in accordance with an embodiment. 
         FIG.  7 C  is a graph of an illustrative relationship between carrier thickness/friction and cell strain in accordance with an embodiment. 
         FIG.  7 D  is a graph of an illustrative relationship between carrier thickness/friction and display wrinkling in accordance with an embodiment. 
         FIG.  8    is a side view of an illustrative convex mold in accordance with an embodiment. 
         FIG.  9 A  is a top view of an illustrative carrier having modified regions to improve strain uniformity in accordance with an embodiment. 
         FIG.  9 B  is a cross-sectional side view of an illustrative patch applied in desired modified regions of a carrier to improve strain uniformity in accordance with an embodiment. 
         FIGS.  10 A- 10 D  are top view of different illustrative patch patterns applied to desired modified regions of a carrier to improve strain uniformity in accordance with an embodiment. 
         FIG.  11    is a flowchart of illustrative steps used in forming a curved display in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Systems may be provided with display devices. In some systems, the display devices may be curved, such as to conform to a curved substrate. For example, the systems may have windows, such as glass windows, on which display devices may be formed to control light transmission through the windows. The systems in which the windows are used may be buildings, vehicles, or other suitable systems. Illustrative configurations in which the system is a vehicle such as an automobile may sometimes be described herein as an example. This is merely illustrative. Windows may be formed in any suitable systems. 
     Windows may have planar surfaces and/or curved surfaces. Windows with curved profiles may be formed by molding or otherwise shaping heated glass. For example, planar glass stock may be processed to form window layers with curved cross-sectional profiles. If desired, multiple glass layers may be laminated together for form laminated window glass. Glass layers may also be chemically and/or thermally tempered. In some embodiments, alternative materials, such as polymer materials, may be used to form the window in addition to, or as an alternative to, glass. 
     An illustrative system of the type that may include display devices, such as display devices on windows, is shown in  FIG.  1   . System  10  may be a vehicle, building, electronic device, or other type of system. In an illustrative configuration, system  10  is a vehicle. As shown in  FIG.  1   , system  10  may have support structures such as body  12 . Body  12  may be a vehicle body that includes doors, trunk structures, a hood, side body panels, a roof, and/or other body structures. Body  12  may be configured to surround and enclose interior region  18 . System  10  may include a chassis to which wheels are mounted, may include propulsion and steering systems, and may include other vehicle systems. Seats may be formed in interior region  18  of body  12 . Window  14 , which may be a vehicle window, and portions of body  12  may be used to separate interior region  18  of system  10  from the exterior environment (exterior region  16 ) that is surrounding system  10 . 
     Windows such as window  14  may be coupled to body  12  and may be configured to cover openings in body  12 . Motorized window positioners may be used to open and close windows  14 , if desired. The windows in system  10  such as window  14  may include a front window mounted within an opening in body  12  at the front of a vehicle, a moon roof (sun roof) window or other window extending over some or all of the top of a vehicle, a rear window at the rear of a vehicle, and/or side windows on the sides of a vehicle. Windows in system  10  may be flat (e.g., a window may lie in the X-Y plane of  FIG.  1   ) and/or windows in system  10  may have one or more curved portions (e.g., window  14  may have a curved cross-sectional profile with one or more bends and may be oriented to lie generally parallel to the X-Y plane so that a convex surface of window  14  faces outwardly in direction Z of  FIG.  1   ). The area of each window  14  in system  10  may be at least 0.1 m 2 , at least 0.5 m 2 , at least 1 m 2 , at least 5 m 2 , at least 10 m 2 , less than 20 m 2 , less than 10 m 2 , less than 5 m 2 , or less than 1.5 m 2  (as examples). 
     System  10  may include control circuitry and input-output devices. Control circuitry in system  10  may include one or more processors (e.g., microprocessors, microcontrollers, application-specific integrated circuits, etc.) and storage (e.g., volatile and/or non-volatile memory). Input-output devices in system  10  may include displays, sensors, buttons, light-emitting diodes and other light-emitting devices, haptic devices, speakers, and/or other devices for providing output and/or for gathering environmental measurements and/or user input. The sensors may include ambient light sensors, touch sensors, force sensors, proximity sensors, optical sensors, capacitive sensors, resistive sensors, ultrasonic sensors, microphones, three-dimensional and/or two-dimensional images sensors, radio-frequency sensors, and/or other sensors. Output devices may be used to provide a user with haptic output, audio output, visual output (e.g., displayed content, light, etc.), and/or other suitable output. During operation, control circuitry in system  10  may gather user input, environmental information, and other information from sensors and/or other input-output devices and may control adjustable components in system  10  based on this gathered information. 
     Window  14  may be formed from one or more layers of transparent glass, clear polymer (e.g., polycarbonate, acrylic, etc.), polymer adhesive, and/or other layers. For example, window  14  may be formed from two glass layers or three glass layers laminated together with adhesive. The glass layers may be chemically or thermally tempered (e.g., to create compressive stress on the surfaces of the glass layers). 
     In the illustrative configuration of  FIG.  1   , window  14  is formed from outer window layer  20  and inner window layer  24  (e.g., outer and inner structural glass layers and/or other layers of transparent material). The thicknesses of layers  20  and  24  may be, for example, 0.5 mm to 3 mm, at least 0.3 mm, at least 0.5 mm, less than 4 mm, less than 3 mm, or other suitable thickness. Outer layer  20  and inner layer  24  may be laminated together using a polymer layer such as interposed adhesive layer  22  (e.g., an adhesive layer with one surface bonded to the inwardly facing surface of outer window layer  20  and an opposing surface bonded to the outwardly facing surface of inner window layer  24 ). Adhesive layer  22  may have a refractive index that is matched (e.g., within 0.15, within 0.1, within 0.07, within 0.05, or within 0.03) to that of layers  20  and  24 . Examples of polymers that may be used for forming adhesive layer  22  include thermoplastic polyurethane, ethylene-vinyl acetate, and polyvinyl butyral. Layer  22  may, if desired, include polymer configured to provide sound dampening (e.g., a soft polyvinyl butyral sublayer or other acoustic film embedded within layer  22 ). Alternatively or additionally, outer layer  20  and inner layer  24  may be separated by an air gap, or by a gap filled with another substance, such as a gas, an inert gas, or vacuum. 
     Outer window layer  20  may be formed from a single layer of structural window glass or may include multiple sublayers such as one or more layers of glass, optically clear adhesive, and/or polymer films. Inner window layer  24  may similarly be formed from a single layer of structural window glass or may include multiple sublayers such as one or more layers of glass, optically clear adhesive, and/or polymer films. In the present example, layers  20  and  24  are glass layers formed from plate glass that is molded or otherwise formed into a desired shape (e.g., in a heated furnace that softens the glass). 
     If desired, optional fixed and/or adjustable optical components may be incorporated into window  14 . As shown in  FIG.  1   , for example, one or more optical components such as optical layer  28  may be incorporated into window  14 . As shown in  FIG.  1   , one or more layers such as optical layer  28  may be attached to an outer surface of inner layer  20 . However, this location of optical layer  28  is merely illustrative. Optical layer  28  may be applied to an inner or outer surface of inner layer  20 , and/or an inner or outer surface of outer layer  24 , as examples. Alternatively or additionally, optical layer  28  may be formed in adhesive  22  or in the gap between outer layer  20  and inner layer  24 . 
     Regardless of where optical layer  28  is formed within window  14 , each optical layer  28  may be a fixed and/or adjustable optical layer providing fixed and/or adjustable amounts of opacity, polarization, reflection, color cast, haze, and/or other optical properties. In an illustrative configuration, optical layer  28  may be a display device (also referred to as a display herein). In particular, optical layer  28  may be a display device that is operable in various modes to allow various amounts of light through window  14 . For example, layer  28  may be a liquid crystal display that exhibits electrically controllable amounts of light attenuation. In general, however, layer  28  may be any desired type of display, such as an organic light-emitting diode (OLED) display or a microLED display. 
     In general, system  10  may include a display device on any desired surface. An example of a display device is shown in  FIG.  2   . 
     As shown in  FIG.  2   , display device  32  may be provided on substrate  30 . Substrate  30  may be a glass layer, a semiconductor layer, a sapphire layer, a ceramic layer, a polymer layer, or any other desired layer. In some embodiments, substrate  30  may be a window layer, such as inner layer  20  or outer layer  24  ( FIG.  1   ), or substrate  30  may be a layer in an electronic device. Display device  32  may be provided on substrate  30 , and may include one or more display layers  34 . Display device  32  may be the same as display device  28  ( FIG.  1   ), if desired. 
     Display layers  34  may include any desired display layers, such as a display substrate, an anode layer, a cathode layer, a thin-film transistor layer, a color filter layer, a liquid crystal layer, a display cover layer (e.g., a transparent layer formed from glass, sapphire, ceramic, etc.), and/or any other suitable display layers. In general, display layers  34  may include display layers that correspond to the type of display device  32 . 
     In some embodiments, it may be desirable to apply display device  32  to a window, such as window  14  ( FIG.  1   ). For example, it may be desirable to control the transmission of light through window  14 . Display device  32  may therefore be applied to one or more layers within window  14  and be controlled by control circuitry within system  10  to control light transmission through the window. In some examples, display device  32  may be adjustable between an opaque state, in which light is blocked from passing through window  14 , and a transparent state, in which light passes freely through window  14 . For example, display  32  may include a liquid crystal layer that may be switched between an opaque state and a transparent state. Alternatively or additionally, display device  32  may be adjusted between these two states, such that less than 75%, less than 50%, or less than 25% of light is transmitted through window  14 , as examples. 
     The windows in system  10  (e.g., windows  14 ) may be completely planar (e.g., the inner and outer surfaces of a window may be flat) and/or some or all of the windows in system  10  may have surface curvature. The inner and outer surfaces of each window may as an example, have compound curvature (e.g., non-developable surfaces characterized by curved cross-sectional profiles taken along the X and Y directions of  FIG.  1   ) and/or may have developable surfaces (surfaces with zero Gaussian curvature that can be flattened without distortion). Curved window shapes may be formed by heating glass until the glass is sufficiently soft to shape (e.g., using a mold, using gravity, using glass slumping techniques, and/or using other glass shaping methods). 
       FIG.  3    is a perspective view of an illustrative curved window layer. In the example of  FIG.  3   , the surface of window  14  (formed by a transparent layer, such as layer  30  of  FIG.  2   ) has compound curvature. In particular, layer  30  has a non-developable surface characterized by curved cross-sectional profiles taken along the X and Y directions of  FIG.  3   .  FIG.  4    is a cross-sectional side view of layer  30  of  FIG.  3    taken along lines  48  and viewed in the +X direction. As shown in  FIG.  4   , the cross-sectional profile of layer  30  viewed in the +X direction is curved.  FIG.  5    is a cross-sectional side view of layer  30  of  FIG.  3    taken along lines  50  of  FIG.  3    and viewed in the +Y direction. As shown in  FIG.  5   , the cross-sectional profile of layer  30  viewed in the +Y direction is curved. Layers  30  with compound curvature may, if desired, also have one or more areas that are planar (not curved) and/or one or more areas that have developable surfaces (curved surface areas without compound curvature). In some configurations, a curved layer such as layer  30  may have only developable surfaces and no compound curvature (and may optionally have planar portions). Arrangements in which curved layers for window  14  such as layer  30  have only compound curvature or a combination of one or more areas of compound curvature and one or more flat areas may also be used. The process of forming layer  30  into a shape with a curved cross-sectional profile may sometimes be referred to as bending or shaping. One or more layers  30  may be used in forming window  14  and each layer  30  (and window  14 ) may have any suitable outline (rectangular, triangular, circular, shapes with curved edges and/or straight edges, etc.). 
     It may be desirable to apply displays to a curved layer, such as layer  30 , to control light transmission through window  14 , or otherwise form a curved display. However, curving displays may apply excessive strain on display layers and may result in undesirable mura on the displays. Excessive strain may also damage layers within a display, such as cracking or other damage in conductors and organic and inorganic dielectric layers. To help reduce the amount of strain applied to a curved display, a carrier layer may be used when the display is being curved. By reducing the amount of strain on a display, there may be fewer or no cracks on layers within the display, and display mura may be reduced or eliminated. An illustrative example of using a carrier layer is shown in  FIG.  6 A . 
     As shown in  FIG.  6 A , display  56  (which may be the same as display device  28  ( FIG.  1   ) and/or display  32  ( FIG.  2   ), if desired) may be applied to carrier  54  (also referred to as a carrier film herein), such as by using an adhesive (e.g., pressure sensitive adhesive) or other suitable material. Display  56  may also referred to as display cell  56  or cell  56  herein. Carrier  54  and display  56  may then be formed to a desired curvature using mold  52 . In some examples, carrier  54  and display  56  may be heated, placed into mold  52 , and then cooled. Carrier  54  and display  56  may then retain a curvature that matches the curvature of mold  52 . However, this is merely illustrative. Any desired method may be used to bend display  56  within mold  52 . 
     Display cell  56  may have a thickness of 200 microns or less, 175 microns or less, 150 microns or more, or any other desired thickness. Cell  56  may include display layers (such as display layers  34  of  FIG.  2   ) formed on a display substrate. The display substrate may be formed from any desired material, such as glass, silicon oxide, plastic, or any other desired substrate. 
     Carrier  54  may have a thickness of at least 100 microns, at least 125 microns, less than 200 microns, or at least 150 microns, as examples. Carrier  54  may be formed of any desired material, such as polyethylene terephthalate (PET). In general, the use of carrier  54  may reduce the strain on display  56  while it is being formed to the desired curvature. For example, using carrier  54  may reduce the strain on display  56  to 12% or less, 15% or less, 10-15%, as examples. 
     Although  FIG.  6 A  shows display cell  56  directly attached to carrier  54  (e.g., with adhesive), this is merely illustrative. In some embodiments, a liner may be used between display cell  56  and carrier  54  to decouple display cell  56  from carrier  54  and reduce the strain on display cell  56 . An illustrative example of using an intervening liner is shown in  FIG.  6 B . 
     As shown in  FIG.  6 B , liner  57  may be interposed between display  56  and carrier  54 . Liner  57  may be formed from polytetrafluoroethylene (PTFE) or other low-friction material. Liner  57  may have a thickness of 25 microns or more, between 25 microns and 100 microns, less than 150 microns, greater than 50 microns, or other suitable thickness. Display  56  may be applied directly to liner  57  and may form with liner  57  due to friction. Alternatively, adhesive may be applied between liner  57  and display cell  56 . 
     Generally, using liner  57  may decouple display cell  56  from carrier  54 . In particular, because display cell  56  is not adhesively bonded to carrier  54 , display cell  56  may be subject to less strain when formed using mold  52 . If desired, the amount of adhesive between carrier  54  and liner  57  and/or between liner  57  and display cell  56  may be adjusted to adjust the strain applied to cell  56 . 
     The material and thickness of both carrier  54  and display  56  may impact the strain on display  56 . Additionally, the amount of friction between carrier  54  and display  56  (e.g., the presence of liner  57 ) may impact the strain on display  56 , as well as whether display  56  wrinkles when formed. Illustrative relationships between the material and thickness of carrier  54  and display  56  vs. the strain on cell  56  and carrier  54  during forming are shown in  FIGS.  7 A and  7 B . Illustrative relationships between the friction between carrier  54  and display  56  vs. the strain on cell  56  and wrinkling of display  56  are shown in  FIGS.  7 C and  7 D . 
     As shown in  FIG.  7 A , the thickness and modulus of elasticity of cell  56  may affect the strain on cell  56  and carrier  54  during forming. As shown by line  58 , as the thickness and modulus of cell  56  increases, the strain on cell  56  during forming may decrease. However, as shown by line  60 , as the thickness and modulus of cell  56  increases, the strain on carrier  54  may increase. Additionally, using cell  56  with a high thickness and modulus may decrease the formability of cell  56 , meaning that it may be more difficult to form cell  56  into the desired curvature. 
     As shown in  FIG.  7 B , the thickness and modulus of elasticity of carrier  54  may also affect the strain on cell  56  and carrier  54  during forming. As shown by line  62 , as the thickness and modulus of carrier  54  increases, the strain on carrier  54  may decrease. Additionally, having a thicker/higher modulus carrier  54  may improve the formability of carrier  54  and cell  56  as it is being formed into the desired curvature. However, as shown by line  64 , as the thickness and modulus of carrier  54  increases, the strain on cell  56  may increase. 
     Therefore, the thickness and modulus of elasticity of both carrier  54  and cell  56  may be chosen to minimize the strain on cell  56  during forming. For example, using carrier  54  and cell  56  of appropriate thicknesses and moduli may reduce the strain on display  56  to 12% or less, 15% or less, 10-15%, as examples. 
     As shown in  FIG.  7 C , as the friction between cell  56  and carrier  54  increases, the strain on cell  56  also increases. By incorporating liner  57  between cell  56  and carrier  54  ( FIG.  6 B ), there is less friction between cell  56  and carrier  54  and therefore less strain applied to cell  56 . However, as shown in  FIG.  7 D , lower friction between cell  56  and carrier  54  may also cause more wrinkles in display  56 . 
     Therefore, the friction between cell  56  and carrier  54  may be adjusted to lower the strain on cell  56  to a suitable amount (e.g., less than 10%, less than 5%, or other suitable strain), while preventing wrinkling on the display. The friction may be adjusted by the presence and thickness of liner  57 , the presence and thickness of adhesive between display  56  and liner  57 , the presence and thickness of adhesive between liner  57  and carrier  54 , and/or the presence of a lubricant. 
     In addition to, or as an alternative to, using a carrier layer and/or liner to reduce the strain on a curved display, a convex mold may be used when curving the display layers to further reduce the strain on the display during forming. An example of an illustrative convex mold that may be used is shown in  FIG.  8   . 
     As shown in  FIG.  8   , mold  66  may be used when forming cell  56  into the desired curvature. Whereas mold  52  of  FIG.  6    was a concave mold, mold  66  is a convex mold have convex curved surface  68 . In other words, cell  56  and carrier  54  may be formed into a convex curve when formed using convex mold  66 . 
     Using convex mold  66  rather than concave mold  52  may reduce the strain on cell  56  by at least 5% or by at least 7%, as examples. Therefore, if used in combination with carrier layer  54  of  FIG.  6   , the strain on cell  56  during the forming operation may be 10% or less, 7% or less, or 5% or less, as examples (with a minimum strain of 0.5%, 1%, or 1.5% across cell  56  due to its curvature, as examples). In this way, the overall strain on cell  56  (display  56 ) may be reduced when forming the display into a desired curvature. By reducing the strain on display  56 , the display may have reduced mura across the display. 
     If desired, one or more surfaces of convex mold  66 , such as mold portion  69 , may be rounded to allow a carrier to both form on and release from mold  66  more effectively. 
     Although using carrier  54  and/or convex mold  66  when forming a display into a desired curvature may reduce the overall strain on the display, there may be regions of the display that are subject to more strain than other regions of the display. Therefore, it may be desirable to distribute the strain on the display more evenly. To distribute the strain more evenly, a region of the carrier (e.g., carrier  54 ) may be modified. In addition to distributing the strain more evenly, modifying the carrier may also further reduce the strain on the curved display. An example of a modified carrier is shown in  FIGS.  9 A and  9 B . 
     As shown in  FIG.  9 A , a carrier, such as carrier  54 , may have a modified region  70 . Modified region  70  may be in the center of carrier  54  as an example. In general, modified region  70  may be modified to have openings, have a different modulus of elasticity, have a different thickness, or otherwise exhibit different properties from the area around modified region  70 . In some examples example, a patch may be selectively applied to carrier  54  to modify region  70 . An example of a patch that may be used with carrier  54  is shown in  FIG.  9 B . 
     As shown in  FIG.  9 B , patch  72  may be applied to carrier  54 . In particular, patch  72  may be applied to the edges of carrier  54 , leaving gap  74 . Patch  72  may have a thickness of at least 75 microns, between 75 microns and 125 microns, between 125 microns and 200 microns, of less than 125 microns, of greater than 50 microns, as examples. Patch  72  may be formed from any desired material, such as a polymer. In general, it may be desirable to use a patch with a relatively high modulus of elasticity, such as a modulus of at least 1.0 GPa. If desired, a lubricant may be added to patch  72  to reduce the friction of patch  72  on a mold during forming. 
     By incorporating patch  72  at the edges of carrier  54  while leaving gap  74 , patch  72  may distribute the strain applied to cell  56  more evenly than if a patch is not used. For example, if a patch is not used, cell  56  may have more strain on the edges than in the center, while a patch of the type shown in  FIG.  9 B  may redistribute the strain more evenly across cell  56  (e.g., by slightly increasing strain on cell  56  in the center while decreasing strain on cell  56  at the edges). In some examples, cell  56  may have a maximum strain of 7% or less, 5% or less, or 10% or less across an entirety of cell  56  (i.e., across an entirety of the display) when formed using a patch, such as patch  72 . In other words, by using patch  72  to local stiffen carrier  54 , the strain uniformity across cell  56  may be improved. 
     Although the example of  FIG.  9 B  shows a patch having two regions with a gap, this is merely illustrative. In general, a patch may be formed on carrier  54  in any desired manner to improve the strain uniformity across cell  56 . Some illustrative configurations of a patch are shown in  FIGS.  10 A-D . 
     As shown in  FIG.  10 A , patch  72  may be applied to the edge regions of carrier  54 , leaving gap  74  extending from one edge to another edge of carrier  54 .  FIG.  10 A  may be a top view of the arrangement shown in  FIG.  9 B , for example. Alternatively, patch  72  may extend around a periphery of carrier  54  and may have opening  74  at the center of patch  72  as shown in  FIG.  10 B . If desired, patch  72  may extend around an inset portion of carrier  54  and leave both opening  74  and peripheral region  74  of carrier  54  uncovered, as shown in  FIG.  10 C . As another example, patch  72  may have upper and lower rectangular portions and central hemispherical portions with an opening  74  and an uncovered peripheral region  74  of carrier  54 , as shown in  FIG.  10 D . In general, patch  72  may have any desired shape. The shape and arrangement of patch  72  may be selected to distribute strain evenly across cell  56 . 
     Although carrier  54  has been described as having patch  72  to modify a region of the carrier and increase the uniformity of strain across cell  56 , this is merely illustrative. In general, carrier  54  may be modified in any desired fashion to distribute the strain more uniformly. As examples, carrier  54  may have one or more openings (such as an array of punch holes in the center of carrier  54 ), one or more thinned regions, or one or more regions formed from material with a different modulus of elasticity. By modifying carrier  54  to have regions with different formability and flexibility, the strain on cell  56  may be more uniformly distributed across cell  56 . 
     In general, a display may be formed to a desire curvature using a carrier and a mold in any desired method. One example of a method that may be used to form a display into a desired curvature is shown in  FIG.  11   . 
     At step  100 , a display (such as display/cell  56 ) may be applied to a carrier (such as carrier  54 ). The carrier may have any desired thickness, such as at least 125 microns. The display may have a thickness of 200 microns or less, as an example. In some illustrative embodiments, the carrier may be modified to improve strain uniformity across the display, such as by applying a patch (such as patch  72 ) to the carrier. The patch may have a thickness of a thickness of at least 75 microns, as an example. Alternatively or additionally, the carrier may be modified by forming openings in the carrier. 
     In some embodiments, a liner may be applied between the display and the carrier. The liner may be formed from polytetrafluoroethylene (PTFE) or other low-friction material, and the liner may have a thickness of 25 microns or more, between 25 microns and 100 microns, less than 150 microns, greater than 50 microns, or other suitable thickness. In general, the liner may decouple the display from the carrier to reduce the strain on the display due to bending the display. 
     At step  110 , the carrier and display may be bent in a convex mold, such as convex mold  66 . Prior to bending the carrier and the display, the carrier and display may be heated, lubricated, and/or otherwise preprocessed to prepare the carrier and display to bend when inserted into the convex mold. 
     At step  120 , the display may be removed from the carrier. In this way, the display may have a curvature that matches the curvature of the convex mold. If desired, the curved display may then be coupled, mounted, or attached to a curved layer, such as a window layer. 
     The foregoing is merely illustrative and various modifications can be made to the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20230525
Publication Date: 20241231
Grant Date: 20241231
Priority Date: 20220629
Inventors: LV, PENG
TOSUN, MAHMUT
LEE, HO HYUNG
TSAO, PAUL W
YU, Da
VOSGUERITCHIAN, MICHAEL
Jacob, Francois R
Assignee: APPLE INC
CPC Classifications: [{"code": "G02F1/1333", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/133305", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/133331", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/133331", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/133331", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 93932954