PATENT DOCUMENT

Publication Number: US-9516743-B2
Application Number: US-201313778932-A
Country: US
Kind Code: B2

Title: Electronic device with reduced-stress flexible display

Abstract:
An electronic device may have a flexible display. The display may have portions that are bent along a bend axis. The display may have display circuitry such as an array of display pixels in an active area and signal lines, thin-film transistor support circuitry and other display circuitry in an inactive area of the display surrounding the active area. The display circuitry may be formed on a substrate such as a flexible polymer substrate. The flexible polymer substrate may be formed by depositing polymer on a support structure that has raised portions. The raised portions may create locally thinned regions in the flexible polymer substrate. The reduced thickness of the flexible polymer substrate in the thinned regions may help ensure that a neutral stress plane that is associated with bending the display along the bend axis is aligned with the display circuitry, thereby minimizing stress in the display circuitry.

Claims:
What is claimed is: 
     
       1. A display, comprising:
 a display substrate having an active area, an inactive area, and a locally thinned region, wherein the locally thinned region is located in the inactive area; 
 an array of display pixels on the display substrate in the active area; 
 display circuitry including gate driver circuitry on the display substrate in the inactive area, wherein the gate driver circuitry overlaps the locally thinned region of the display substrate, wherein the display pixels lie in a plane, and wherein the locally thinned region of the display substrate curves out of the plane such that the inactive area is at least partially hidden from view by a user; and 
 an encapsulation layer formed over the gate driver circuitry such that a neutral stress plane intersects with and spans laterally across the entire width of the gate driver circuitry over the locally thinned region of the display substrate. 
 
     
     
       2. The display defined in  claim 1  wherein the inactive area does not contain display pixels. 
     
     
       3. The display defined in  claim 2  wherein the display circuitry includes a plurality of metal lines in the inactive area, wherein the metal lines overlap the locally thinned region, and wherein the metal lines curve with the locally thinned region. 
     
     
       4. The display defined in  claim 3  wherein the metal lines include serpentine segments that curve with the locally thinned region of the display substrate. 
     
     
       5. The display defined in  claim 1  wherein the display pixels comprise organic light-emitting diode display pixels. 
     
     
       6. The display defined in  claim 1  wherein the display circuitry includes thin-film transistors. 
     
     
       7. The display defined in  claim 1  wherein the display substrate comprises a polymer layer. 
     
     
       8. The display defined in  claim 7  wherein the encapsulation layer comprises a polymer encapsulation layer on the display substrate. 
     
     
       9. The display defined in  claim 8  wherein at least a portion of the neutral stress plane lies within the polymer encapsulation layer. 
     
     
       10. A method of forming a display, comprising:
 depositing a polymer display substrate layer onto a support structure having raised areas so that the raised areas create recesses within the polymer display substrate layer and create corresponding locally thinned regions of the polymer display substrate layer that are thinned relative to an adjacent region of the polymer display substrate layer, wherein the polymer display substrate layer has a first thickness in the locally thinned regions and a second thickness in the adjacent region and wherein the first thickness is less than the second thickness; 
 forming an insulating layer above the polymer display substrate layer; 
 forming display circuitry including at least one thin-film transistor on the polymer display substrate layer that at least partly overlaps the locally thinned regions; and 
 forming an encapsulant layer over the display circuitry such that a neutral stress plane runs through the thin-film transistor where the thin-film transistor overlaps one of the locally thinned regions, wherein a thickness of the encapsulant layer and the insulating layer is less than the second thickness of the polymer display substrate layer in the adjacent region. 
 
     
     
       11. The method defined in  claim 10  further comprising:
 removing the deposited polymer display substrate layer and the display circuitry from the support structure. 
 
     
     
       12. The method defined in  claim 11  further comprising:
 bending the polymer display substrate layer and display circuitry that have been removed from the support structure along the locally thinned regions. 
 
     
     
       13. The method defined in  claim 12  wherein forming the display circuitry comprises forming an array of display pixels in an active area on the display, wherein the active area is surrounded by an inactive border area, wherein the locally thinned regions are in the inactive border area, and wherein bending the polymer display substrate layer comprises bending the polymer display substrate layer in the inactive border area. 
     
     
       14. An electronic device, comprising:
 a housing having an interior surface; and 
 a flexible display mounted in the housing, wherein the flexible display has at least one edge that is bent along a bend axis and wherein the flexible display includes a polymer substrate with a first and second regions separated by a locally thinned region that overlaps the bend axis, wherein the flexible display includes a metal trace formed on the polymer substrate and an encapsulant layer formed on the metal trace such that a neutral stress plane intersects with the metal trace where the metal trace overlaps the locally thinned region and such that tensile stress is formed in the encapsulant layer where the encapsulant layer overlaps the metal trace, wherein the first region of the polymer substrate defines a plane, wherein the second region of the polymer substrate is bent out of the plane, and wherein the second region of the polymer substrate is parallel to the interior surface of the housing. 
 
     
     
       15. The electronic device defined in  claim 14  wherein the flexible display includes an array of organic light-emitting diode display pixels in an active area, wherein the metal trace is one of a plurality of metal traces in an inactive area that surrounds the active area, and wherein the metal traces include at least some bent metal traces in the portion of the flexible display that overlaps the locally thinned region.

Description:
BACKGROUND 
     This relates generally to electronic devices, and more particularly, to electronic devices with displays. 
     Electronic devices often include displays. For example, cellular telephones and portable computers often include displays for presenting information to a user. 
     It can be challenging to form displays for electronic devices. Displays have active areas formed from arrays of display pixels. Inactive border regions surround the active regions. The inactive border region in a display contains support circuitry such as signal lines and thin-film transistor circuitry but does not contain active pixels for producing images for a user. To reduce the apparent size of the inactive border region, it may be desirable to use a flexible substrate in forming the display. This allows portions of the inactive border region to be bent out of sight, thereby reducing the size of the visible inactive display border and enhancing the appearance of the display. Active display regions may also be bent. For example, an active display region may be bent so that a display conforms to the curved shape of a device housing. 
     Challenges arise when bending displays. If care is not taken, metal signal lines can crack and display pixel circuitry can become damaged. Damage to display components such as these may cause the display to fail prematurely. 
     It would therefore be desirable to be able to provide improved displays for electronic devices. 
     SUMMARY 
     An electronic device may be provided with a flexible display. The display may have portions that are bent along a bend axis. For example, the edges of the display may be bent to help hide inactive display components from view by a user of the electronic device. 
     The display may have display circuitry such as an array of display pixels in an active area of the display. The active area may, for example, have a rectangular shape. The display may also have signal lines, thin-film transistor support circuitry, and other display circuitry in an inactive area of the display. The inactive area may, for example, have the shape of a rectangular ring that surrounds the active area. 
     The display circuitry may be formed on a substrate such as a flexible polymer substrate. The flexible polymer substrate may be formed by depositing a polymer layer on a temporary support structure that has raised portions. The raised portions may create corresponding locally thinned regions in the flexible polymer substrate. The reduced thickness of the thinned portions of the flexible polymer substrate may help ensure that a neutral stress plane that is associated with bending the display along the bend axis is aligned with the display circuitry, thereby minimizing stress in the display circuitry. 
     Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device such as a laptop computer with a display in accordance with an embodiment of the present invention. 
         FIG. 2  is a perspective view of an illustrative electronic device such as a handheld electronic device with a display in accordance with an embodiment of the present invention. 
         FIG. 3  is a perspective view of an illustrative electronic device such as a tablet computer with a display in accordance with an embodiment of the present invention. 
         FIG. 4  is a perspective view of an illustrative electronic device such as a computer display with display structures in accordance with an embodiment of the present invention. 
         FIG. 5  is diagram of an array of display pixels in a display in accordance with an embodiment of the present invention. 
         FIG. 6  is a circuit diagram of an illustrative display pixel in a display in accordance with an embodiment of the present invention. 
         FIG. 7  is a top view of a portion of an illustrative display showing how the display may be bent along a bend axis that runs through signal lines in an inactive area of the display or that runs through an array of display pixels in an active area of the display in accordance with an embodiment of the present invention. 
         FIG. 8  is a top view of an illustrative display showing how the left side of the display may be bent along a bend axis that runs through gate driver circuitry in an inactive portion of the display and showing how the right side of the display may be bent along a bend axis that runs through gate driver circuitry in an inactive portion of the in accordance with an embodiment of the present invention. 
         FIG. 9  is a cross-sectional side view of a portion of a bent display showing how stresses may be imposed on display circuitry in a flexible display in the absence of localized display substrate thinning in accordance with an embodiment of the present invention. 
         FIG. 10  is a cross-sectional side view of a portion of a display showing how stresses on display circuitry may be minimized by locally thinning a flexible display substrate layer under display circuitry that overlaps a bend in the display in accordance with an embodiment of the present invention. 
         FIG. 11  is a cross-sectional side view of a display with multiple display pixels or other display circuits that overlap a locally thinned substrate region in accordance with an embodiment of the present invention. 
         FIG. 12  is a cross-sectional side view of a portion of an illustrative flexible display that has been bent at an angle of less than 90° in accordance with an embodiment of the present invention. 
         FIG. 13  is a cross-sectional side view of a portion of an illustrative flexible display that has been bent at a right angle in accordance with an embodiment of the present invention. 
         FIG. 14  is a cross-sectional side view of a portion of an illustrative flexible display that has been bent sufficiently to fold back on itself in accordance with an embodiment of the present invention. 
         FIG. 15  is a diagram of equipment and fabrication operations involved in forming an electronic device with a flexible display in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices may include displays. The displays may be used to display images to a user. Illustrative electronic devices that may be provided with displays are shown in  FIGS. 1, 2, 3, and 4 . 
       FIG. 1  shows how electronic device  10  may have the shape of a laptop computer having upper housing  12 A and lower housing  12 B with components such as keyboard  16  and touchpad  18 . Device  10  may have hinge structures  20  that allow upper housing  12 A to rotate in directions  22  about rotational axis  24  relative to lower housing  12 B. Display  14  may be mounted in upper housing  12 A. Upper housing  12 A, which may sometimes referred to as a display housing or lid, may be placed in a closed position by rotating upper housing  12 A towards lower housing  12 B about rotational axis  24 . 
       FIG. 2  shows how electronic device  10  may be a handheld device such as a cellular telephone, music player, gaming device, navigation unit, or other compact device. In this type of configuration for device  10 , housing  12  may have opposing front and rear surfaces. Display  14  may be mounted on a front face of housing  12 . Display  14  may, if desired, have openings for components such as button  26 . Openings may also be formed in display  14  to accommodate a speaker port (see, e.g., speaker port  28  of  FIG. 2 ). 
       FIG. 3  shows how electronic device  10  may be a tablet computer. In electronic device  10  of  FIG. 3 , housing  12  may have opposing planar front and rear surfaces. Display  14  may be mounted on the front surface of housing  12 . As shown in  FIG. 3 , display  14  may have an opening to accommodate button  26  (as an example). 
       FIG. 4  shows how electronic device  10  may be a computer or television display or a computer that has been integrated into a display. With this type of arrangement, housing  12  for device  10  may be mounted on a support structure such as stand  27 . Display  14  may be mounted on a front face of housing  12 . 
     The illustrative configurations for device  10  that are shown in  FIGS. 1, 2, 3, and 4  are merely illustrative. In general, electronic device  10  may be a laptop computer, a computer monitor containing an embedded computer, a tablet computer, a cellular telephone, a media player, or other handheld or portable electronic device, a smaller device such as a wrist-watch device, a pendant device, a headphone or earpiece device, or other wearable or miniature device, a television, a computer display that does not contain an embedded computer, a gaming device, a navigation device, an embedded system such as a system in which electronic equipment with a display is mounted in a kiosk or automobile, equipment that implements the functionality of two or more of these devices, or other electronic equipment. 
     Housing  12  of device  10 , which is sometimes referred to as a case, may be formed of materials such as plastic, glass, ceramics, carbon-fiber composites and other fiber-based composites, metal (e.g., machined aluminum, stainless steel, or other metals), other materials, or a combination of these materials. Device  10  may be formed using a unibody construction in which most or all of housing  12  is formed from a single structural element (e.g., a piece of machined metal or a piece of molded plastic) or may be formed from multiple housing structures (e.g., outer housing structures that have been mounted to internal frame elements or other internal housing structures). 
     Display  14  may be a touch sensitive display that includes a touch sensor or may be insensitive to touch. 
     Touch sensors for display  14  may be formed from an array of capacitive touch sensor electrodes, a resistive touch array, touch sensor structures based on acoustic touch, optical touch, or force-based touch technologies, or other suitable touch sensor components. 
     Display  14  for device  10  includes display pixels formed from organic light-emitting diode components or other suitable display pixel structures. An optional display cover layer such as a planar or curved transparent glass or plastic sheet or other transparent member may be cover the outer surface of display  14  (if desired). Edge portions of display  14  may be bent to hide inactive border regions of display  14  from view. Display  14  may also be bent to provide display  14  with a curved surface shape (e.g., a gently curving shape that extends across the entire width of display  14 ). Other types of bends may be formed in display  14  if desired. 
     To ensure that bending operations do not damage display  14 , display  14  may be provided with locally thinned regions. The locally thinned regions may help move the neutral stress plane of the display into alignment with sensitive display circuitry, thereby eliminating or at least minimizing the amount of stress imposed on the display circuitry. 
       FIG. 5  is a top view display  14 . As shown in  FIG. 5 , display  14  may include display pixel array  36 . Display pixel array  36  includes rows and columns of display pixels  30 . Display pixels  30  may be, for example, organic light-emitting-diode pixels. Gate lines  32  and data lines  34  may be used to supply control signals to the array of display pixels  30 . Display pixel array  36  may have a rectangular shape in the center of display  14 . Display pixel array  36  may form an active region (active area AA) of display  14  that displays images to a user of device  10 . The active area AA of display  14  may be surrounded by an inactive border region such as rectangular ring-shaped inactive area IA of  FIG. 5 . Inactive area IA may contain support circuitry such as thin-film transistors in gate driver circuitry and other thin-film transistor circuits, signal lines formed from metal traces, and other display circuitry that does not emit light for creating images for the user. The support circuitry in inactive area IA and the circuitry of display pixel array  36  in active area AA may potentially be subjected to stresses when display  14  is bent. By using localized thinning of the substrate layer in display  14 , the stresses that are imposed on the display circuitry can be minimized. 
       FIG. 6  is a circuit diagram of an illustrative organic light-emitting diode display pixel  30 . As shown in  FIG. 6 , display pixel  30  may have thin-film transistor circuitry such as thin-film transistor  38 . Thin-film transistor  38  may be coupled between one of data lines  34  and a patch of light-emitting organic material  40 . The gate terminal of thin-film transistor  38  may be coupled to one of gate lines  32 . Other types of display pixels  30  may be used in display pixel array  36  of display  14  if desired. The example of  FIG. 6  is merely illustrative. 
       FIG. 7  is a top view of a portion of an illustrative display. As shown in  FIG. 7 , display  14  may have display support circuitry such as support circuitry  42 . Support circuitry  42  may include one or more integrated circuits (e.g., display driver integrated circuits), thin-film transistor circuitry, and/or other circuitry for controlling the operation of display  14 . Support circuitry  42  may be located in a portion of inactive area IA. Display pixel array  36  may be located in active area AA of display  14 . 
     It may be desirable to bend display  14  along one or more bend axes. To fit display  14  within the tight confines of a device housing or to fold inactive portions of display  14  out of view, for example, it may be desirable to fold display  14  along a bend axis such as bend axis  44  in inactive area IA. To help prevent signal lines such as data lines  34  from becoming damaged, the signal lines may be provided with meandering portions  34 M or other structures that help lines  34  resist bend-induced damage. In some electronic device configurations, it may be desirable to provide the surface of display  14  in active area AA with a bend. It may, for example, be desirable to bend display  14  along a bend axis such as bend axis  46  that runs through active area AA of display  14 . 
     As shown in the top view of illustrative display  14  of  FIG. 8 , display  14  may include support circuitry such as gate driver circuitry  48 . Gate driver circuitry  48  may include latches and buffer circuits for supplying gate line control signals to gate lines  32 . Thin-film transistors and metal traces for signal lines may be used in forming gate driver circuitry  48 . In configurations for display  14  in which it is desired to minimize the size of the inactive left and right borders of the display, display  14  may be bent downwards along left-hand bend axis  50 , which overlaps gate driver circuitry  48  on the left-hand side of display  14  and/or display  14  may be bent downwards along right-hand bend axis  52 , which overlaps gate driver circuitry  48  on the right-hand side of display  14 . Display  14  may also have other bent portions, if desired. 
     Whether bending display  14  along a bend axis such as bend axis  44  that overlaps inactive area IA in a display with a configuration of the type shown in  FIG. 7 , bending display  14  along a bend axis such as bend axis  46  that overlaps active area AA in a display with a configuration of the type shown in  FIG. 7 , or bending display  14  along a bend axis such as bend axis  50  or  52  that overlaps inactive left and right border regions IA in a display of the type shown in  FIG. 8 , it may be desirable to ensure that the display circuitry of display  14  is not damaged. Localized substrate thinning may be used to prevent damage. 
     A cross-sectional side view of a bent flexible display that is not using localized substrate thinning is shown in  FIG. 9 . Display  66  of  FIG. 9  has flexible polyimide substrate layer  54  with a thickness T 3  (e.g., 10 microns). An insulating layer  56  of thickness T 2  (e.g., layer of an inorganic material such as silicon nitride or silicon oxide or a polymer layer) may be formed on substrate layer  54 . Display circuitry  60  such as metal traces for signal lines, thin-film transistors for gate driver circuitry and other support circuitry, thin-film transistors for display pixels, or other circuitry may be formed on the surface of layer  56 . Polymer encapsulant layer  58  covers display circuitry  60  and substrate  54 . The thicknesses T 1  and T 2  of encapsulant layer  58  and insulating layer  56  may be characterized by a total thickness of about 3000 angstroms (as an example). 
     When display  66  is bent as shown in  FIG. 9 , tensile stress is created in the upper portion of substrate  54 , as indicated by arrows  64 , whereas compressive stress is created in the lower portion of substrate  54 , as indicated by arrows  62 . It may be desirable to minimize the thickness of layers  56  and  58  to avoid creating an overly bulky configuration for display  66 . However, the large thickness of substrate  54  relative to the flexible over-coating layer formed from layers such as layers  56  and  58  with this type of configuration causes the neutral stress plane for display  66  (i.e., the plane in which stress is a minimum because tensile stress  64  is balanced by compressive stress  62 ), to lie deep within layer  54 . Neutral stress plane  68  may, for example, lie at a distance TN from the lower surface of layer  54 . Because neutral stress plane  68  lies deep within layer  54 , neutral stress plane  68  is located relatively far away from display circuitry  60  (i.e., a distance TG away). 
     As a result, display circuitry  60  of  FIG. 9  is subjected to significant tensile stress  64 . The tensile stress that is applied to display circuitry  60  in display  66  has the potential to render display  66  inoperable or to reduce the expected operating lifetime of display  66 . 
     The stress that is induced in the display circuitry of  FIG. 9  may be reduced by thinning the display substrate in appropriate portions of the display. The portions of the display that are not thinned are sufficiently thick to ensure that the display is robust and strong enough to be handled during assembly and use in device  10 . The portions of the display that are locally thinned have a neutral plane that is vertically aligned with the thin-film transistors, metal lines, and other display circuitry, thereby preventing damage to the display circuitry from bend-induced stress. 
     An illustrative configuration for display  14  in which the display substrate has been thinned in this way is shown in the cross-sectional side view of  FIG. 10 . As shown in  FIG. 10 , display  14  of  FIG. 10  has flexible substrate layer  72 . Flexible substrate layer  72  may be formed from a sheet of flexible polymer such as a sheet of polyimide (as an example). The thickness TC of display substrate  72  may be about 10 microns, less than 10 microns, less than 5 microns, more than 10 microns, 1-20 microns, 5-30 microns, or other suitable thickness. 
     An optional insulating layer  74  of thickness TB (e.g., layer of an inorganic material such as silicon nitride or silicon oxide or a polymer layer) may be formed on substrate layer  74 . Display circuitry  78  such as metal traces for signal lines, thin-film transistors for gate driver circuitry such as gate driver circuitry  48  of  FIG. 8 , thin-film transistors for display support circuitry  42 , thin-film transistors for display pixels  30  of display pixel array  36 , thin-film transistors for other display circuitry, and other display circuitry  78  may be formed on the surface of layer  74 . 
     Polymer encapsulant layer  76  covers display circuitry  78  and substrate  72  (including substrate coating layer  74 ). Thicknesses TA and TB of encapsulant layer  76  and insulating layer  74 , respectively, may have a total thickness of 3000 angstroms, less than 3000 angstroms, 1000 to 5000 angstroms, more than 3000 angstroms, or other thickness. To minimize the thickness of display  14 , thicknesses TA and TB are generally less than thickness TC of substrate TC. 
     When bent as shown in  FIG. 10 , tensile stress is created in display  14 , as indicated by arrows  80 , and compressive stress is created in display  14 , as indicated by arrows  82 . In locally thinned region  70 , recess  84  is created in substrate layer  72 , so that substrate layer  72  has a thickness TD in thinned region  70  that is thinner than substrate thickness TC elsewhere in substrate  72 . Due to the relative thinness of thinned portion  72 ′ of substrate  72  in region  70 , compressive stress  82  in the layers of display  14  is formed relatively close to display circuitry  78  and tensile stress  80  is formed in encapsulant layer  76 , rather than in substrate  72 . As a result, neutral stress plane  86  is vertically aligned with display circuitry  78  (i.e., neutral stress plane passes through display circuitry  78  or near to display circuitry  78 ). This minimizes bending-induced stress in display circuitry  78  and avoids creating premature failures in circuitry  78  due to bending of flexible display  14 . 
     In configurations in which layers  72 ,  74 , and  76  are formed from the same or similar materials, neutral plane  86  will tend to be located midway between the outer surface of layer  76  and the inner surface of portion  72 ′ of layer  72  (i.e., distances TM and TM′ of  FIG. 10  will be equal). If desired, different types of materials may be used in forming substrate  72  and other layers in display  14  (e.g., materials with different Young&#39;s modulus values). When different types of materials are used in the layers of display  14 , the sizes of TM′ and TM may differ while ensuring that neutral plane  86  is aligned with display circuitry  78 . In particular, TM′ may be smaller than TM (e.g., when relatively more tensile stress is produced in layer  76  than compressive stress is produced in layer  72  for a given thickness) or TM′ may be larger than TM (e.g., when relatively less tensile stress is produced in layer  76  than compressive stress is produced in layer  72  for a given thickness). The relative thicknesses and materials used for the upper and lower layers of display  14  and the depth of recess  84  in locally thinned region  70  are preferably selected so that neutral plane  86  will coincide with display circuitry  78 , thereby minimizing damage to display circuitry  78  when display  14  is bent. 
     As shown in  FIG. 11 , multiple display pixels  30  or other display circuits may overlap a single recess  84  (i.e., thinned region  70  may span multiple rows or columns of display pixels  30  in display pixel array  36 ). In configurations in which thinned region  70  is formed under signal lines or display support circuitry in inactive area IA, each thinned region  70  may overlap one or more signal lines and/or one or more gate driver circuits or other display support circuits. To facilitate bending of display  14  along the edges of display  14 , thinned region  70  may span the entire width (or entire height) of display  14  (e.g., region  70  may extend into the page across all of display  14  in the orientation of  FIG. 11 ). 
       FIG. 12  is a cross-sectional side view of display  14  in a configuration in which display  14  has been bent downwards from a horizontal plane that encompasses the surface of display  14  by an angle of less than 90°. Locally thinned region  70  may extend along the bent edge of display (e.g., into the page of  FIG. 12 ) to prevent damage to overlapping display circuitry  78 . Housing  12  covers the bent edge of display  14  in the  FIG. 12  configuration. This is merely illustrative. The bent edges of display  14  may be visible, may be covered by housing portions, or may be mounted in device  10  using other techniques. 
     In the  FIG. 13  example, the edge of display  14  has been bent at a right angle, allowing display  14  to be mounted within housing  12  of device  10 . Locally thinned region  70  may run along the edge of display  14  parallel with the bend axis of the right angle bend (i.e., region  70  may extend into the page in the orientation of  FIG. 13 ). 
     In the  FIG. 14  example, display  14  has an edge that has been folded back on itself. Locally thinned region  70  may run along the edge of display  14  and housing  12  (into the page in the orientation of  FIG. 14 ). By locally thinning display  14  along its bent edge, damage to display circuitry  78  due to bending stresses at the edge of display  14  may be minimized. 
     Other configurations for mounting a display with bent portions into housing  12  of device  10  may be used if desired. The illustrative schemes of  FIGS. 12, 13, and 14  are merely illustrative. 
       FIG. 15  is a diagram of fabrication steps and equipment of the type that may be used in forming a device having a flexible display with bent portions in accordance with an embodiment of the present invention. 
     As shown in  FIG. 15 , deposition and patterning equipment  92  may be used to form raised structures  94  on the surface of support structure  90 . Support structure  90  may be a sheet of glass, a layer of a plastic or ceramic, or other planar support member. Raised structures  94  may be thin-film structures formed from a material such as silicon nitride, other inorganic materials, or other materials. Deposition and patterning equipment  92  may include physical vapor deposition equipment and other equipment for depositing a blanket layer of silicon nitride or other thin film on the surface of support member  90 . Deposition and patterning equipment  92  may also include photolithographic patterning equipment (e.g., equipment for depositing and patterning photoresist, equipment for dry or wet etching of the deposited blanket thin film that has been deposited on planar support member  90 , etc.). In general, raised areas  94  of support member  90  may be formed using screen printing, pad printing, ink-jet printing, shadow mask deposition, electrochemical deposition, chemical vapor deposition, or other techniques. The use of photolithography to pattern a blanket thin film inorganic layer on the top surface of support member  90  is merely illustrative. 
     The shapes in which raised areas  94  are formed on support member  90  correspond to the desired locally thinned regions in display  14 . For example, if it is desired to form locally thinned display substrate regions in strips along the left and right edges of display  14 , raised regions  94  may have the shape of elongated strips that run parallel to the left and right edges of display  14 . 
     Planar support member  90  and the raised structures formed from patterned thin-film layer  94  serve as a polymer shaping structure for forming locally thinned regions  70  in deposited polymer material. As shown in  FIG. 15 , after thin-film layer  94  has been patterned onto the surface of support structures  90  to form raised areas, polymer deposition equipment such as polymer film slit coating equipment  96  or other equipment for applying liquid polymer to the surface of structures  94  and  90  may be used to deposited polymer substrate layer  72  as a coating on the surface of support structure  90 . Equipment  96  may, for example, include a liquid polymer slit dispenser that deposits a thin layer of liquid polymer over the surface of support member  90  and associated raised portions  94 . Equipment  96  may also include light sources such as an ultraviolet light source, heat sources, or other equipment for curing the deposited polymer of substrate layer  72 . If desired, the display substrate layer  72  may be formed from a material that cures at room temperature (e.g., a two-part adhesive, etc.). The use of a thermally cured polymer or ultraviolet-light-cured polymer in forming polymer display substrate layer  72  is merely illustrative. 
     After forming display substrate layer on support structures  90  and raised areas  94  of support structure  90 , device processing equipment and polymer film removal equipment  98  may be used in removing polymer substrate  72  from support structures  90  and raised areas  94 . Equipment  98  may include thin-film processing equipment for forming thin-film transistors, equipment for depositing and patterning metal to form metal traces for signal lines, and other fabrication equipment for forming transistors, conductive lines, and other display circuitry. The display circuitry that is formed may include display pixels  30  in display pixel array  36 , gate driver circuitry  48  ( FIG. 8 ), display driver circuitry and other support circuitry  42  ( FIGS. 7 and 8 ), and other display circuitry  78 . Equipment  98  may also include deposition equipment for forming layers such as insulating layer  74  and encapsulation layer  76  of  FIG. 10 . 
     After substrate  72  and associated structures such as display circuitry  78  and encapsulation layer  76  have been formed, these layers may be peeled off of support structure  90  and raised areas  94  on support structure  90 . The portions of substrate layer  72  that were formed on top of raised portions  94  will be recessed (i.e., these portions will form recesses  84  for locally thinned regions  70 ), as shown in  FIG. 15 . If, for example, raised portions  94  have the shape of elongated vertical strips of material running along the left and right sides of display  14 , the resulting recessed portions  84  and locally thinned regions  70  of display  14  will have corresponding elongated strip shapes. 
     Following formation of flexible display  14  with locally thinned regions  70  using equipment  98 , assembly equipment  100  may be used to bend display  14  and mount display  14  within housing  12  and device  10 . Assembly equipment  100  may, for example, bend display  14  along one or more of its edges and/or may create a curved surface for display pixel array  36  in display  14  by bending display  14  in its active area AA. Bent edges or other bends in display  14  may be associated with right angle bends in substrate  72  and/or bends at shallower or deeper angles. 
     The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention.

Metadata:
Filing Date: 20130227
Publication Date: 20161206
Grant Date: 20161206
Priority Date: 20130227
Inventors: KIM KYUNG WOOK
PARK YOUNG BAE
CHANG SHIH CHANG
YANG BYUNG DUK
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F1/1652", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/028", "inventive": true, "first": true, "tree": "[]"}, {"code": "Y02E10/549", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/0278", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/0278", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/1652", "inventive": true, "first": true, "tree": "[]"}, {"code": "Y02E10/549", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2251/5338", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y02E10/549", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/028", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K1/0278", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/1652", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L51/0097", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L27/3244", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K77/111", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K2102/311", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K59/12", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K77/111", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K2102/311", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K59/12", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 51387939