PATENT DOCUMENT

Publication Number: US-10056443-B2
Application Number: US-201615251612-A
Country: US
Kind Code: B2

Title: Electronic devices with displays

Abstract:
An electronic device may have a flexible portion that allows the device to be folded. The device may have a flexible display. The flexible display may have edge portions that are joined along a flexible middle portion. The flexible middle portion may overlap a bend axis and may be bent about the bend axis. Flexibility enhancement regions may be formed in a backing layer, polarizer layer, organic-light-emitting display layer, and other display layers to enhance flexibility for the middle portion. The device may have a display with a flexible tail that is bent about a bend axis. Metal trace on the flexible display may include metal trace strips that serve as power lines. Flexibility enhancement regions such as slot-shaped openings or other openings may be formed in the metal trace strips to enhance flexibility.

Claims:
What is claimed is: 
     
       1. An electronic device that folds about a bend axis, comprising:
 a housing having edge portions and having a middle portion that is coupled between the edge portions; and 
 a flexible display having edge portions in the edge portions of the housing and having a flexible middle portion that overlaps the middle portion of the housing, wherein the flexible display has a backing layer, a flexible organic light-emitting diode display layer, and a polarizer layer, wherein at least the backing layer has a plurality of elongated flexibility enhancement regions in the flexible middle portion, wherein each of the elongated flexibility enhancement regions extends along the bend axis to enhance flexibility of the flexible middle portion of the flexible display as the flexible display bends about the bend axis, wherein the polarizer has an index of refraction, and wherein the polarizer has recesses that are filled with material having an index of refraction that is matched to the index of refraction of the polarizer. 
 
     
     
       2. The electronic device defined in  claim 1  wherein the elongated flexibility enhancement regions comprise staggered slots. 
     
     
       3. The electronic device defined in  claim 2  wherein the slots extend through the backing layer. 
     
     
       4. The electronic device defined in  claim 2  wherein the slots extend only partway through the backing layer. 
     
     
       5. The electronic device defined in  claim 4  wherein the slots include slots of different depths. 
     
     
       6. The electronic device defined in  claim 2  further comprising elastomeric material in the slots. 
     
     
       7. The electronic device defined in  claim 2  wherein the slots are laser-formed openings and wherein the backing layer comprises a polymer layer through which the laser-formed openings pass. 
     
     
       8. An electronic device that folds about a bend axis, comprising:
 a housing having edge portions and having a middle portion that is coupled between the edge portions; and 
 a flexible display having edge portions in the edge portions of the housing and having a flexible middle portion that overlaps the middle portion of the housing, wherein the flexible display has a backing layer, a flexible organic light-emitting diode display layer, and a polarizer layer, wherein at least the backing layer has a plurality of elongated flexibility enhancement regions in the flexible middle portion and wherein each of the elongated flexibility enhancement regions extends along the bend axis to enhance flexibility of the flexible middle portion of the flexible display as the flexible display bends about the bend axis, and wherein the plurality of elongated flexibility enhancement regions are arranged with a density that decreases with increasing distance from the bend axis. 
 
     
     
       9. The electronic device defined in  claim 8 , wherein the elongated flexibility enhancement features comprise openings that extend completely through the backing layer. 
     
     
       10. The electronic device defined in  claim 8 , wherein the flexible display comprises an array of display pixels that overlaps the edge portions and the flexible middle portion of the flexible display. 
     
     
       11. The electronic device defined in  claim 10 , wherein the flexible display is configured to be folded along the bend axis such that portions of the array of display pixels that overlap the edge portions face each other. 
     
     
       12. An electronic device that folds about a bend axis, comprising:
 a housing having edge portions and having a middle portion that is coupled between the edge portions; and 
 a flexible display having edge portions in the edge portions of the housing and having a flexible middle portion that overlaps the middle portion of the housing, wherein the flexible display has a backing layer, a flexible organic light-emitting diode display layer, and a polarizer layer, wherein at least the backing layer has a plurality of elongated flexibility enhancement regions in the flexible middle portion and wherein each of the elongated flexibility enhancement regions extends along the bend axis to enhance flexibility of the flexible middle portion of the flexible display as the flexible display bends about the bend axis, wherein the backing layer is a layer of polymer, and wherein the flexibility enhancement regions are at least partially uncured portions of the layer of polymer surrounded by cured portions of the layer of polymer. 
 
     
     
       13. The electronic device defined in  claim 12 , wherein the elongated flexibility enhancement features comprise at least partially uncured portions of the layer of polymer that extend completely through the backing layer. 
     
     
       14. The electronic device defined in  claim 12 , wherein the elongated flexibility enhancement features comprise at least partially uncured portions of the layer of polymer that extend only partially through the backing layer. 
     
     
       15. The electronic device defined in  claim 12 , wherein the flexible display comprises an array of display pixels that overlaps the edge portions and the flexible middle portion of the flexible display. 
     
     
       16. The electronic device defined in  claim 15 , wherein the flexible display is configured to be folded along the bend axis such that portions of the array of display pixels that overlap the edge portions face each other.

Description:
This application claims priority to provisional patent application No. 62/320,333, filed Apr. 8, 2016, 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, computers, cellular telephones, and other devices may use displays to present visual information to a user. It may be desirable to provide displays with flexible portions. This may allow portions of a display to be bent. Care must be taken, however, to ensure that displays are sufficiently robust to avoid damage when bent. 
     SUMMARY 
     An electronic device may have a flexible portion that allows the device to be folded. The device may have a flexible display and a housing in which the flexible display is mounted. 
     The housing and the flexible display may have edge portions that are joined along a flexible middle portion. The flexible middle portion may overlap a bend axis. The housing and flexible display may be bent about the bend axis. Flexibility enhancement regions may be formed in a backing layer, polarizer layer, a display layer such as an organic-light-emitting display layer or micro-light-emitting diode display layer, and may be formed in adhesive layers and other layers within the display to enhance bending about the bend axis. 
     The device may have a display with a flexible tail. The flexible tail may be bent about a bend axis when the display is mounted in a housing. Metal trace on the flexible display may include metal trace strips that serve as power lines. Flexibility enhancement regions such as slot-shaped openings or other openings may be formed in portions of the metal trace strips that overlap across the bend axis. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device with 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 circuit diagram of an illustrative pixel in a 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  is a cross-sectional side view of an illustrative display with light-emitting diode pixels formed from individual crystalline semiconductor light-emitting diode dies in accordance with an embodiment. 
         FIG. 6  is a side view of an illustrative display with a bend in an active area of the display in accordance with an embodiment. 
         FIG. 7  is a side view of an illustrative display with a bend in an inactive area of the display in accordance with an embodiment. 
         FIG. 8  is a cross-sectional side view of an illustrative display in accordance with an embodiment. 
         FIGS. 9, 10, 11, 12, and 13  are top views of illustrative bend regions in a display having enhanced flexibility regions in accordance with an embodiment. 
         FIGS. 14, 15, 16, and 17  are side views of a display layer showing illustrative configurations for enhanced flexibility regions in a display in accordance with an embodiment. 
         FIG. 18  is a diagram showing how patterned curing techniques may be used in forming a display with enhanced flexibility regions in accordance with an embodiment. 
         FIG. 19  is a diagram showing how material removal techniques such as laser drilling techniques may be used in forming a display with enhanced flexibility regions in accordance with an embodiment. 
         FIGS. 20A and 20B  are top views of a display having a mesh structure such as a metal mesh in a bendable portion of the display in accordance with an embodiment. 
         FIGS. 21A and 21B  are side views of a display having ribs that extend parallel to a bend axis in a bendable portion of the display in accordance with an embodiment. 
         FIG. 22  is a diagram showing how a touch sensor may be provided with enhanced flexibility regions in accordance with an embodiment. 
         FIG. 23  is a cross-sectional side view of an illustrative flexible display structure with metal traces for data and power signals in accordance with an embodiment. 
         FIGS. 24, 25, and 26  are top views of illustrative metal trace patterns for bendable display structures in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An electronic device such as electronic device  10  of  FIG. 1  may have a display such as display  14 . Device  10  may be a laptop computer, a tablet computer, a cellular telephone, a wristwatch, or other electronic device (e.g., a portable device, handheld device, etc.). 
     Display  14  may be mounted in a housing such as housing  12 . Housing  12  may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of any two or more of these materials. 
     Display  14  may be a touch screen display that incorporates a layer of conductive capacitive touch sensor electrodes or other touch sensor components (e.g., resistive touch sensor components, acoustic touch sensor components, force-based touch sensor components, light-based touch sensor components, etc.) or may be a display that is not touch-sensitive. Capacitive touch screen electrodes may be formed from an array of indium tin oxide pads or other transparent conductive structures (as an example). 
     Display  14  may include an array of display pixels formed from liquid crystal display (LCD) components, an array of electrophoretic display pixels, an array of plasma display pixels, an array of organic light-emitting diode display pixels, an array of pixels formed from crystalline semiconductor light-emitting diode dies (sometimes referred to as micro-LEDs), an array of electrowetting display pixels, or display pixels based on other display technologies. Examples in which display  14  has been formed from organic light-emitting diode pixels or micro-LED pixels may sometimes be described herein as an example). 
     Display  14  may have one or more portions that bend. The bent portions may be flexed back and forth during use of device  10  (e.g., when device  10  is being opened and closed like a book) or may be placed in a permanent bent configuration (e.g., when an inactive portion of display  14  is bent to accommodate mounting in a compact housing). 
     In the illustrative example of  FIG. 1 , device  10  is bendable (foldable) along bend axis  16 . To accommodate bending about bend axis  16 , display  14  and housing  12  may have a flexible portion that overlaps bend axis  16 . For example, display  14  may have a flexible central portion  14 M and housing  12  may have an associated bendable central portion that runs along bend axis  16 . Bendable portion  14 M may be interposed between edge portions  14 E of display  14 . Edge portions  14 E may be rigid or flexible. For example, edge portions  14 E may be flexible display portions that are held rigid by rigid edge portions of housing  12 . Display  14  may be folded so that display portions  14 E face each other and/or so that portions  14 E face away from each other. 
       FIG. 2  is a diagram of an illustrative display. As shown in  FIG. 2 , display  14  may have an array of pixels  24  formed on a substrate such as substrate  20 . Display driver circuitry  22  may include gate driver circuitry that is used to supply control signals G (sometimes referred to as horizontal control signals, emission control signals, scan signals, gate line signals, etc.) on horizontal lines (sometimes referred to as gate lines). There may be one or more gate lines associated with each row of pixels  24 . Gate driver circuitry may be located along one edge of display  14  (e.g., the left edge of display  14 ) and/or two edges of display  14  (see, e.g., illustrative gate driver circuitry  22 ′ on the right edge of display  14  in the example of  FIG. 2 ). While control signals are being supplied to rows of pixels  24  using gate lines G, display driver circuitry  22  may be used to supply data signals D to pixels  24  using data lines that run along respective columns of pixels  24 . During operation, the active area AA of display  14 , which contains pixels  24 , displays images for a user. The inactive area IA of display  14  that runs along the borders of active area AA does not have any pixels  24  and therefore does not display images. Circuitry such as display driver circuitry  22 , routing lines, and other non-pixel circuitry may be located in inactive area IA. 
     An illustrative circuit of the type that may be used for pixels  24  is shown in  FIG. 3 . As shown in  FIG. 3 , pixel  24  may have pixel control circuitry  32  and light-emitting diode  28 . Control circuitry  32  may receive data signals D on vertical data lines and may receive control signals G on one or more horizontal control lines (gate lines). Control circuitry  32  may contain switching transistors, emission enable transistors, a drive transistor that controls current flow through light-emitting diode  28 , capacitors, and other circuitry (see, e.g., illustrative transistor and capacitor circuitry  26 ). Power lines such as metal traces on display substrate  20  may carry positive power supply signal ELVDD and ground power supply signal ELVSS. Signals ELVDD and ELVSS may be used to power circuitry  32 . During operation, current is supplied to diode  28  that is proportional to the data loaded into circuitry  32 , causing diode  28  to emit a desired amount of light  30 . Pixels  24  may contain light-emitting diodes  28  of different colors (e.g., red, green, and blue) so that display  14  has the ability to display color images. 
     Light-emitting diode  28  and circuitry  32  may, if desired, be formed from thin-film circuitry. As shown in the illustrative cross-sectional side view of display  14  of  FIG. 4 , for example, display  14  may have an array of pixels  24  that are formed from thin-film layers (thin-film circuitry)  34  on substrate  36 . In this type of thin-film display arrangement, light-emitting diode  28  may be an organic light-emitting diode and substrate  36  may be a flexible polymer substrate. Configurations in which light-emitting diodes  28  in display  14  are formed from discrete semiconductor dies may also be used (see, e.g., display  14  of  FIG. 5  in which packaged or unpackaged micro-LEDs  24 P have been coupled to traces  38  on flexible polymer substrate  36 ). 
     Displays such as illustrative displays  14  of  FIGS. 4 and 5  may be bent about bend axis  16 , as illustrated in the display side views of  FIGS. 6 and 7 . In the example of  FIG. 6 , bend axis  16  overlaps active area AA of display  14 . When a user desires to fold display  14  for storage or to otherwise adjust display  14  in this type of configuration, active area AA of display  14  may be bent along bend axis  16 . In the example of  FIG. 7 , inactive area IA of display  14  has been bent about bend axis  16 . As shown in  FIG. 7 , display driver circuitry  22  (e.g., one or more display driver integrated circuit dies) may be mounted to printed circuit  42 . Printed circuit  42 , in turn, may be coupled to traces  40  in flexible tail portion  14 T in inactive area IA of display  14 . Inactive tail portion  14 T of display  14  may be a thin extending portion of one or more flexible polymer layers or other layers in active area AA of display  14  and may bend about bend axis  16  to accommodate the mounting of display  14  of  FIG. 7  in a compact enclosure (as an example). 
     To accommodate either one-time bending or repeated folding and unfolding, the portions of display  14  that bend are preferably resistant to damage (e.g., cracking of brittle layers, plastic deformation, delamination, etc.). To help enhance durability, display  14  may be provided with enhanced flexibility regions. These regions may take the form of slots or other openings in the layers of display  14  and may help reduce potentially damaging stresses in one or more of the layers of display  14  during bending. 
     Display  14  may have a separate touch sensor layer, may have touch sensor structures that are formed from conductive traces on the same substrate as the circuitry that forms pixels  24 , or may not be touch sensitive.  FIG. 8  is a cross-sectional side view of display  14  in an illustrative configuration in which display  14  has a touch sensor formed on a substrate layer that is attached to a flexible display layer using adhesive. Other configurations may be used for display  14  if desired (e.g., touch and/or protective layers may be omitted, additional layers may be added above or below the display, etc.). The configuration of  FIG. 8  is presented as an example. 
     In the illustrative configuration of  FIG. 8 , display  14  has a support layer  14 - 1  (sometimes referred to as substrate, backing layer, or backing film) such as layer  14 - 1 . Layer  14 - 1  may be, for example, a flexible polymer layer or a thin flexible metal layer (e.g., a nickel titanium layer). Layer  14 - 2  may be a layer of adhesive that attaches flexible display layer  14 - 3  to support layer  14 - 1 . Flexible display layer  14 - 3 , which may sometimes be referred to as a flexible display, may be, for example, an organic light-emitting diode display, a micro-LED display, or other flexible display. Adhesive layer  14 - 4  may be used to attach touch sensor (touch sensor layer)  14 - 5  to layer  14 - 3 . Touch sensor  14 - 5  may be formed from transparent conductive capacitive touch sensor electrodes (e.g., indium tin oxide electrodes) on a transparent polymer substrate (as an example). If desired, touch sensor electrodes may be integrated into layer  14 - 3 . Outer layer  14 - 7  of display  14  may include a polarizer (e.g., a circular polarizer formed from one or more flexible polymer layers to reduce reflections from layer  14 - 3 ), an inorganic scratch resistant layer (sometimes referred to as a hard coat), moisture barrier structures, coatings to promote smudge resistance, an antireflection layer, and/or other protective and functional layers. Adhesive layer  14 - 6  may be used to attach outer layer (polarizer layer)  14 - 7  to touch sensor  14 - 5 . Adhesive layers in display  14  may be formed from pressure sensitive adhesive, liquid adhesive (e.g., ultraviolet light curable liquid adhesive, etc.), or other suitable adhesive and may, if desired, be optically clear. Flexible substrate layers for support layer  14 - 1 , display layer  14 - 3 , and touch sensor  14 - 5 , may be formed from flexible polymers such as polyimide, polyethylene terephthalate (PET) or other polyesters, acrylic, or other polymers. If desired, metals may be incorporated into the layers of display  14  (e.g., as metal traces on substrates, a thin sheet of metal for forming support layer  14 - 1  or other layers, etc.). Semiconductor thin-films may be formed in display  14 - 3  (e.g., to form thin-film transistors). Other materials may also be used in forming one or more layers of display  14  (e.g., nanowires and other nanomaterials, fiber composite materials such as carbon fiber materials, ceramics, glass, etc.). 
     To prevent damage to display  14  during bending, one or more of layers  14 - 1 ,  14 - 2 ,  14 - 3 ,  14 - 4 ,  14 - 5 ,  14 - 6 , and  14 - 7  and/or other display layers may be provided with flexibility enhancement regions. An illustrative configuration for display  14  in which one or more layers of display  14  have been provided with flexibility enhancement regions is shown in  FIG. 9 . As shown in  FIG. 9 , display  14  may have edge portions  14 E. Central flexible portion  14 M may extend between edge portions  14 E. Central flexible portion  14 M may run along and overlap bend axis  16 . 
     To enhance the flexibility of display  14  and thereby help reduce bend-induced stresses, solid portion  14 R of one or more layers in region  14 M may be provided with enhanced flexibility regions  14 EF. Regions  14 EF may be openings (e.g., through-holes), may be grooves or other recesses, or may have other configurations. In the example of  FIG. 9 , regions  14 EF have elongated slot shapes. Regions  14 EF may have dimensions such as widths X 1  and lengths X 3 , may be separated along their lengths by gaps X 2  and along their widths by gaps X 4 . Region  14 M may have a width X 5 . With one illustrative configuration, X 1  may be 100 microns, more than 10 microns, or less than 500 microns, X 2  may be 5 mm, more than 1 mm, or less than 2 cm, X 3  may be 500 microns, more than 100 microns, less than 2 mm, X 4  may be 500 microns, more than 100 microns, less than 2 mm, etc., and X 5  may be 100 microns to 1 cm, more than 1 mm, or less than 5 mm, and/or these dimensions may have any other suitable values. Slot-shaped elongated openings or other elongated flexibility enhancement regions  14 EF such as regions  14 EF of  FIG. 9  may be staggered (as shown in  FIG. 9 ) to help preserve the structural integrity of the display layer(s) in which regions  14 EF have been formed. 
     Regions  14 EF may be circular (as shown in  FIG. 10 ), may be rectangular (as shown in  FIG. 11 ), or may have any other suitable shape. Regions  14 EF may be distributed in a regular periodic pattern (e.g., an array having rows and columns) or may be distributed pseudorandomly (see, e.g., the illustrative aperiodic distribution of  FIG. 12 ). If desired, regions  14 EF may be distributed with a density that varies across region  14 M (see, e.g.,  FIG. 13  in which regions  14 EF decrease in density with increasing distance  44  from bend axis  16 ). 
     Regions  14 EF may pass entirely through a display layer (see, e.g., through-hole openings  14 EF of  FIG. 14 ), may pass partly through a display layer (see, e.g., recesses  14 EF of  FIG. 15 ), may include through-hole openings and/or recesses of one or more different depths (see, e.g., illustrative regions  14 EF of  FIG. 15 ), and/or may be formed on one or more sides of a display layer (see, e.g.,  FIG. 17 ). 
     As shown in  FIGS. 14, 15, 16, and 17 , regions  14 EF may be filled with a flexible material. The flexible material may be a liquid, a gel, foam, a solid polymer (e.g., a soft elastomeric polymer), a liquid polymeric material, or other flexible material. The flexible material in regions  14 EF may be formed from a material that is more flexible and/or different than the material of region  12 R. If desired, regions  14 EF may be filled with air or other gaseous material. 
       FIG. 18  shows how light-source  46  (e.g., an ultraviolet light source) may supply ultraviolet light  48  when processing a display layer. Mask  50  may have openings  52  that allow light  48  to selectively cure a liquid polymer precursor material to form stiffer regions  14 R in the display layer. Uncured portions of the liquid polymer material may remain uncured or partly cured and may remain in liquid form or may otherwise be more flexible than cured stiffer regions  14 R. This allows the uncured portions to serve as enhanced flexibility regions. If desired, etching equipment, cutting equipment, machining equipment, laser-processing equipment, or other material removal tools may be used in removing portions of a display layer to form regions  14 EF (see, e.g.,  FIG. 19  in which laser  56  produces laser beam  58  to laser drill recesses or openings in layer  14 R that serve as enhanced flexibility regions  14 EF). After removing material from regions of a display layer, the regions may contain air or may optionally be filled with a material such as liquid, gel, solid polymer (e.g., polymer that is more flexible than the non-removed polymer), or other material that allows the regions to bend. 
     When filling regions of a layer in display with material to form enhanced flexibility regions  14 EF (or when leaving liquid polymer regions uncured), the added material (or uncured material) may be opaque or transparent. Transparent filler materials may be used in scenarios in which image light from pixels  24  is passing through the transparent filler. In situations such as these, the transparent filler material may be index matched to the unremoved portions of the display layer (e.g., the index of refraction of the material that is added to regions  14 EF may vary by less than 0.1 or by less than 0.05 or other suitable amount from the index of refraction of remaining material  14 R). Index matching may help reduce light scattering. 
     As shown in  FIG. 20A , portion  14 M of display  14  may have one or more layers with a mesh structure such as grid  60 . Grid  60  may be formed from metal wires or a sheet of metal with openings (e.g., an array of rectangular openings or openings of other shapes). The openings in mesh  60  may be filled with air or filler material  62  (e.g., elastomeric material, etc.). Grid  60  may be formed from wires, fine lines of a metal thin-film, or other material. The lines may be sufficiently narrow to be invisible to a user of device  10  and/or grid  60  may be formed in a layer of display  14  that is not visible to the user (see, e.g., backing film  14 - 1  of  FIG. 8 ). Backing film  14 - 1  may also be formed from a metal sheet (e.g., a thin sheet of nickel titanium or other flexible metal). To enhance the flexibility of a metal backing film, the metal sheet may be provided with flexibility enhancement regions  14 F (e.g., staggered slot-shaped openings, an array of rectangular or circular openings, openings of other shapes, etc.). A metal sheet with grooves or other recesses that pass only partway through the metal sheet may also be used in forming a backing film  14 - 1 . In the example of  FIG. 20A , the lines of mesh  60  run parallel and perpendicular to bend axis  16 .  FIG. 20B  shows how the lines of mesh  60  may be oriented so that they run at 45° relative to bend axis  16 . Other mesh orientations and layouts may be used if desired. Fiber-based materials may also be used in forming layers in display  14 . For example, backing layer  14 - 1  may be formed from a flexible fiberglass layer or other fiber-impregnated material (e.g., an elastomeric material with glass or carbon fibers, etc.). 
     As shown in the cross-sectional side view of display  14  of  FIG. 21A , one or more of the layers of display  14  (e.g., backing layer  14 - 1 ) may be provided with protrusions that help provide support while retaining flexibility. In the example of  FIG. 21A , a layer of display  14  has series of parallel ribs  64  in region  14 M (i.e., elongated raised portions that run parallel to bend axis  16 ).  FIG. 21B  shows how the depressed regions between adjacent pairs of ribs may help enhance the flexibility by facilitating bending around bend axis  16 . 
     Display  14  may have a touch sensor. The touch sensor may be a stand-alone capacitive touch sensor layer such as layer  14 - 5  of  FIG. 8  or may be formed from capacitive touch sensor electrodes that have been integrated into display  14 - 3 . 
     A top view of an illustrative touch sensor is shown in  FIG. 22 . As shown in  FIG. 22 , touch sensor  66  may have drive lines DR and perpendicular sense lines SN. Touch sensor circuitry  72  may be coupled to drive lines DR and to sense lines SN. Touch sensor circuitry  72  may supply drive signals to drive lines DR and may monitor sense lines SN for signals that have been coupled into a given sense line SN from one of drive lines DR due to the presence of a user&#39;s finger or other overlapping external component (e.g., a stylus) at the intersection between that drive line and sense line. 
     Capacitive touch sensors may use single-sided or double-sided electrode patterns. Capacitive touch sensor electrodes may be formed from transparent conductive material such as indium tin oxide. As an example, each drive line DR in sensor  66  of  FIG. 22  may be formed from a horizontal strip of indium tin oxide on the upper surface of a clear plastic substrate and each sense line SN in sensor  66  may be formed from a vertical strip of indium tin oxide on the lower surface of the clear plastic substrate. Enhanced flexibility regions  70  may be formed in the substrate layer and/or electrode layer(s) of touch sensor  66 . Regions  70  may, for example, run along and overlap bend axis  16 , as shown in  FIG. 22 . Regions  70  may be formed from staggered slots or other elongated openings in the indium tin oxide layers and/or the clear plastic substrate, from grooves or other recesses in these layers, etc. The area consumed by regions  70  may be relatively small and there may be spaces between regions  70 , so the presence of the enhanced flexibility regions  70  may only slightly raise the resistance of the touch sensor electrodes, thereby ensuring that touch sensor  66  may operate satisfactorily. 
       FIG. 23  is a cross-sectional side view of a portion of display  14  (e.g., a portion in an inactive tail region such as region  14 T of  FIG. 7 ). As shown in  FIG. 23 , a display portion such as portion  14 T may have a substrate such as substrate  74  (e.g., a layer of polyimide or other flexible polymer layer). Metal traces  80  may be patterned onto layer  74  and used to form data line signal paths (DATA) and power paths (e.g., positive power supply path ELVDD and a pair of flanking ground power supply paths ELVSS in the  FIG. 23  example). Planarization layer  76  may be formed from a polymer layer that is deposited as a liquid and that remains flexible when cured to a solid state. Optional neutral stress plane adjustment layer  78  may be formed on top of layer  76  and may be used to ensure that the neutral stress plane of tail  14 T is aligned with metal traces  80  when tail  14 T is bent about bend axis  16  as shown in  FIG. 7 , thereby minimizing bending-induced stress in traces  80 . By minimizing stress in traces  80 , faults due to trace cracks may be avoided. 
     Stress that has the potential to lead to undesired cracks in metal traces  80  may also be minimized by selection of appropriate shapes for traces  80  in the portion of traces  80  that runs across bend axis  16 . In the example of  FIG. 24 , traces  80  for DATA, ELVSS, and ELVDD have serpentine shapes (i.e., the traces are serpentine metal lines). This may help minimize trace stress, because serpentine paths can stretch slightly when bent about axis  16 . In the example of  FIG. 25 , data lines DATA are formed from serpentine traces  80  and power lines (e.g., ELVSS and ELVDD) have been formed from solid metal trace strips to help reduce power line resistance.  FIG. 26  shows how solid metal trace strips for power traces such as ELVSS and ELVDD (i.e., metal trace strips  80 R) may be provided with flexibility enhancement regions  80 EF. Flexibility enhancement regions  80 EF may be, for example, staggered slots or other elongated openings that pass through traces  80 R or may be openings of other suitable shapes. Regions  80 EF do not completely span the widths of traces  80 R, so traces  80 R remain conductive. If desired, patterned thin-film metal traces such as the traces of  FIGS. 24, 25 , and/or  26  or other serpentine traces and/or traces with openings that serve as flexibility enhancement regions may be formed in multiple layers of a display and may be shorted together using metal vias. 
     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: 20160830
Publication Date: 20180821
Grant Date: 20180821
Priority Date: 20160408
Inventors: SHYU, TERRY C.
DRZAIC, PAUL S.
ZHANG, ZHEN
Assignee: APPLE INC
CPC Classifications: [{"code": "H01L27/3276", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L27/3211", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L51/5281", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L27/3248", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01L51/5243", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F2203/04102", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L51/0097", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/044", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L27/323", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/041", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L2251/5338", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y02E10/549", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/044", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y02E10/549", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/041", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/044", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F2203/04102", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K59/40", "inventive": true, "first": true, "tree": "[]"}, {"code": "H10K77/111", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K2102/311", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K59/40", "inventive": true, "first": true, "tree": "[]"}, {"code": "H10K59/123", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K59/35", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K59/131", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K77/111", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K2102/311", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K50/8423", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K50/86", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K59/131", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K59/8721", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K59/8791", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 59998869