PATENT DOCUMENT

Publication Number: US-11525955-B1
Application Number: US-202117327441-A
Country: US
Kind Code: B1

Title: Electronic devices with drawn sheet-packed coherent fiber bundles

Abstract:
An electronic device may have a display, a display cover layer, and a drawn sheet-packed coherent fiber bundle. The coherent fiber bundle may have an input surface that receives an image from the display and a corresponding output surface to which the image is transported. The coherent fiber bundle may be placed between the display and the display cover layer and mounted to a housing. The coherent fiber bundle may have fiber cores with bends that help conceal the housing from view and make the display appear borderless. The coherent fiber bundle has filaments formed from elongated strands of binder in which multiple fibers are embedded. Sheets of filaments are stacked and fused together to form a block of material that is subsequently drawn to form the drawn sheet-packed coherent fiber bundle.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a display configured to produce an image; and 
 a drawn sheet-packed coherent fiber bundle overlapping the display, wherein the drawn sheet-packed coherent fiber bundle is configured to receive the image at an input surface and to transport the received image to an output surface and wherein the drawn sheet-packed coherent fiber bundle comprises a coherent fiber bundle block drawn from a fused set of sheets of filaments. 
 
     
     
       2. The electronic device defined in  claim 1  wherein the drawn sheet-packed coherent fiber bundle has fibers and wherein 90% of the fibers in the drawn sheet-packed coherent fiber bundle are separated from neighboring fibers by gaps of less than 0.7 microns. 
     
     
       3. The electronic device defined in  claim 1  wherein the drawn sheet-packed coherent fiber bundle is characterized by a fiber bundle draw ratio of at least three. 
     
     
       4. The electronic device defined in  claim 1  wherein the drawn sheet-packed coherent fiber bundle has fibers and wherein at least 90% of the fibers in the drawn sheet-packed coherent fiber bundle are angularly misaligned by less than 0.8°. 
     
     
       5. The electronic device defined in  claim 4  wherein the drawn sheet-packed coherent fiber bundle forms an image transport layer with a thickness of at least 1.2 mm. 
     
     
       6. The electronic device defined in  claim 1  wherein the drawn sheet-packed coherent fiber bundle has fibers and wherein 90% of the fibers in the drawn sheet-packed coherent fiber bundle exhibit lateral misalignment at the input surface of less than 30 microns. 
     
     
       7. The electronic device defined in  claim 1  wherein the display has pixels, wherein each pixel has a lateral dimension and wherein 90% of the fibers in the drawn sheet-packed coherent fiber bundle exhibit lateral misalignment at the input surface of less than 50% of the lateral dimension. 
     
     
       8. The electronic device defined in  claim 1  wherein the drawn sheet-packed coherent fiber bundle comprises additional coherent fiber bundle blocks fused together with the coherent fiber bundle block and wherein each of the additional coherent fiber bundle blocks is drawn from a respective fused set of sheets of filaments. 
     
     
       9. The electronic device defined in  claim 1  wherein the drawn sheet-packed coherent fiber bundle has additional fused sheets of filaments. 
     
     
       10. The electronic device defined in  claim 9  wherein each fused sheet of filaments has fiber cores with cladding layers embedded in binder. 
     
     
       11. The electronic device defined in  claim 1  wherein each filament in the fused set of sheets of filaments has multiple fiber cores. 
     
     
       12. The electronic device defined in  claim 11  wherein the fiber cores include fiber cores with multiple bends. 
     
     
       13. An electronic device, comprising:
 a display having pixels configured to produce an image; and 
 a coherent fiber bundle that overlaps the display, wherein the coherent fiber bundle comprises fibers, wherein each pixel has a lateral dimension, wherein the coherent fiber bundle has an input surface that is configured to receive the image and has a corresponding output surface to which the image is transported, and wherein 90% of the fibers in the coherent fiber bundle exhibit lateral misalignment at the input surface of less than 50% of the lateral dimension. 
 
     
     
       14. The electronic device defined in  claim 13  wherein the coherent fiber bundle comprises a drawn stack of fused filament sheets that is characterized by a draw ratio of at least 2.5. 
     
     
       15. The electronic device defined in  claim 14  wherein the drawn stack of fused filament sheets has fused filaments each of which includes more than one of the fibers. 
     
     
       16. The electronic device defined in  claim 15  wherein the fibers include fibers with multiple bends. 
     
     
       17. The electronic device defined in  claim 13  wherein 90% of the fibers are separated from neighboring fibers by gaps of less than 0.7 microns. 
     
     
       18. The electronic device defined in  claim 13  wherein at least 90% of the fibers are angularly misaligned by less than 0.8°. 
     
     
       19. An image transport layer configured to receive an image at an input surface and to transport the image to a corresponding output surface, comprising:
 a drawn sheet-packed coherent fiber bundle extending between the input surface and the output surface, wherein the drawn sheet-packed coherent fiber bundle is drawn from fused sheets of filaments, each sheet having multiple fused filaments. 
 
     
     
       20. The image transport layer defined in  claim 19  wherein each filament includes multiple fibers in binder. 
     
     
       21. The image transport layer defined in  claim 20  wherein 90% of the fibers are separated from neighboring fibers by gaps of less than 0.7 microns. 
     
     
       22. The image transport layer defined in  claim 20  wherein at least 90% of the fibers are angularly misaligned by less than 0.8°.

Description:
This application claims the benefit of U.S. provisional patent application No. 63/035,584, filed Jun. 5, 2020, which is hereby incorporated by reference herein in its entirety. 
    
    
     FIELD 
     This relates generally to electronic devices, and, more particularly, to coherent fiber bundles for electronic devices with displays. 
     BACKGROUND 
     Electronic devices may have displays. Displays have arrays of pixels for displaying images for a user. To protect sensitive display structures from damage, displays may be provided with display cover layers. Display cover layers may be formed from glass, crystalline materials such as sapphire, or polymer. 
     SUMMARY 
     An electronic device may have a display, a display cover layer, and a drawn sheet-packed coherent fiber bundle. The coherent fiber bundle may have an input surface that receives an image from the display and a corresponding output surface to which the image is transported. The coherent fiber bundle may be placed between the display and the display cover layer and mounted to a housing. The coherent fiber bundle may have fiber cores with bends that help conceal the housing from view and make the display appear borderless. 
     The coherent fiber bundle may have filaments formed from elongated strands of binder in which multiple fiber cores are embedded. Sheets of filaments can be stacked and fused together to form a sheet-stacked coherent fiber bundle. The sheet-stacked coherent fiber bundle is drawn to form the drawn sheet-packed coherent fiber bundle. 
     The process of drawing the sheet-packed coherent fiber bundle reduces the lateral dimensions of the coherent fiber bundle. The drawing process also helps reduce fiber misalignment and the lateral separation between fiber cores, thereby helping to enhance optical quality. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a side view of an illustrative electronic device with an image transport layer in accordance with an embodiment. 
         FIG.  2    is a cross-sectional view of a portion of an illustrative image transport layer formed using a coherent fiber bundle in accordance with an embodiment. 
         FIG.  3    is a perspective view of a portion of an image transport layer surface with compound curvature in accordance with an embodiment. 
         FIG.  4    is a top view of an illustrative electronic device in accordance with an embodiment. 
         FIG.  5    is a cross-sectional side view of a portion of an illustrative coherent fiber bundle having a misaligned fiber in accordance with an embodiment. 
         FIG.  6    is a cross-sectional view of a coherent fiber bundle having closely spaced fibers in accordance with an embodiment. 
         FIG.  7    is a side view of illustrative equipment for forming filaments from elongated strands of binder with embedded fibers in accordance with an embodiment. 
         FIG.  8    is a side view of illustrative equipment for forming sheets of fused filaments for an image transport layer in accordance with an embodiment. 
         FIG.  9    is a cross-sectional view of an illustrative alignment wheel for use in equipment that forms filament sheets such as the illustrative equipment of  FIG.  8    in accordance with an embodiment. 
         FIG.  10    is a cross-sectional view of illustrative sheet fusing rollers for use in equipment that forms filament sheets such as the illustrative equipment of  FIG.  8    in accordance with an embodiment. 
         FIG.  11    is a cross-sectional side view of an illustrative bobbin with channels into which sheets of filaments may be placed during sheet packing operations in accordance with an embodiment. 
         FIG.  12    is a cross-sectional view of an illustrative bobbin and associated sheets of filaments in accordance with an embodiment. 
         FIG.  13    is a diagram of illustrative drawing equipment for drawing a sheet-packed coherent fiber bundle in accordance with an embodiment. 
         FIG.  14    is a cross-sectional side view of illustrative fusing equipment for fusing together subblocks of drawn sheet-packed coherent fiber bundle material in accordance with an embodiment. 
         FIG.  15    is a flow chart of illustrative operations involved in forming an electronic device with a drawn sheet-packed coherent fiber bundle in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An electronic device may have a display. The display may have an array of pixels for creating an image. The image may be visible through transparent structures that overlap the array of pixels. These structures may include an image transport layer such as a coherent fiber bundle overlapped by a clear display cover layer. 
     The coherent fiber bundle may be included in the electronic device to help minimize display borders or to otherwise create a desired appearance for the display. The coherent fiber bundle may have an input surface that receives an image from an array of pixels and a corresponding output surface to which the image is transported from the input surface. A layer of glass, polymer, or other clear material may be used to form a display cover layer that protects the output surface. A user viewing the electronic device will view the image from the array of pixels as being located on the output surface. In some arrangements, image transport layers formed from coherent fiber bundles and/or protective cover layers can be formed over components other than displays. 
     In configurations in which the input and output surfaces of an image transport layer such as a coherent fiber bundle have different shapes, the image transport layer may be used to warp the image produced by the array of pixels. For example, the shape of the image can be transformed and the effective size of the image can be changed as the image passes through the image transport layer. In some configurations, edge portions of the image are stretched outwardly to help minimize display borders. 
     Glass, polymer, and/or other transparent materials may be used in forming image transport layer structures. Display cover layers for protecting underlying display structures such as pixel arrays and image transport layers may be formed from transparent materials such as glass, clear polymer, or crystalline material such as sapphire. 
     A cross-sectional side view of a portion of an illustrative electronic device having a display that includes an image transport layer is shown in  FIG.  1   . In the example of  FIG.  1   , device  10  is a portable device such as a cellular telephone, wristwatch, or tablet computer. In general, any type of electronic device may have an image transport layer such as a desktop computer, a voice-control speaker, a television or other non-portable display, a head-mounted device, an embedded system such as a system built into a vehicle or home, an electronic device accessory, and/or other electronic equipment. 
     Device  10  includes a housing such as housing  12 . Housing  12  may be formed from polymer, metal, glass, crystalline material such as sapphire, ceramic, fabric, fibers, fiber composite material, natural materials such as wood and cotton, other materials, and/or combinations of such materials. Housing  12  may be configured to form housing walls. The housing walls may enclose one or more interior regions such as interior region  24  and may separate interior region  24  from exterior region  22 . For example, housing  12  may have a rear housing wall on rear face R and this rear housing wall may separate interior region  24  from exterior region  22 . In some configurations, an opening may be formed in housing  12  for a data port, a power port, to accommodate audio components, or to accommodate other devices. Clear housing regions may be used to form optical component windows. Dielectric housing structures may be used to form radio-transparent areas for antennas and wireless power components. 
     Electrical components  18  may be mounted in interior region  24 . Electrical components  18  may include integrated circuits, discrete components, light-emitting components, sensors, and/or other circuits and may, if desired, be interconnected using signal paths in one or more printed circuits such as printed circuit  20 . If desired, one or more portions of the housing walls may be transparent (e.g., so that light associated with an image on a display or other light-emitting or light-detecting component can pass between interior region  24  and exterior region  22 ). 
     Electrical components  18  may include control circuitry. The control circuitry may include storage and processing circuitry for supporting the operation of device  10 . The storage and processing circuitry may include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in the control circuitry may be used to control the operation of device  10 . For example, the processing circuitry may use sensors and other input-output circuitry to gather input and to provide output and/or to transmit signals to external equipment. The processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio chips, application specific integrated circuits, etc. The control circuitry may include wired and/or wireless communications circuitry (e.g., antennas and associated radio-frequency transceiver circuitry such as cellular telephone communications circuitry, wireless local area network communications circuitry, etc.). The communications circuitry of the control circuitry may allow device  10  to communicate with other electronic devices. For example, the control circuitry (e.g., communications circuitry in the control circuitry) may be used to allow wired and/or wireless control commands and other communications to be conveyed between devices such as cellular telephones, tablet computers, laptop computers, desktop computers, head-mounted devices, handheld controllers, wristwatch devices, other wearable devices, keyboards, computer mice, remote controls, speakers, accessory displays, accessory cameras, and/or other electronic devices. Wireless communications circuitry may, for example, wirelessly transmit control signals and other information to external equipment in response to receiving user input or other input from sensors or other devices in components  18 . 
     Input-output circuitry in components  18  of device  10  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. The input-output circuitry may include input devices that gather user input and other input and may include output devices that supply visual output, audible output, or other output. 
     Output may be provided using light-emitting diodes (e.g., crystalline semiconductor light-emitting diodes for status indicators and/or displays, organic light-emitting diodes in displays and other components), lasers, and other light-emitting devices, audio output devices (e.g., tone generators and/or speakers), haptic output devices (e.g., vibrators, electromagnetic actuators, piezoelectric actuators, and/or other equipment that supplies a user with haptic output), and other output devices. 
     The input-output circuitry of device  10  (e.g., the input-output circuitry of components  18 ) may include sensors. Sensors for device  10  may include force sensors (e.g., strain gauges, capacitive force sensors, resistive force sensors, etc.), audio sensors such as microphones, touch and/or proximity sensors such as capacitive sensors (e.g., a two-dimensional capacitive touch sensor integrated into a display, a two-dimensional capacitive touch sensor and/or a two-dimensional force sensor overlapping a display, and/or a touch sensor or force sensor that forms a button, trackpad, or other input device not associated with a display), and other sensors. Touch sensors for a display or for other touch components may be based on an array of capacitive touch sensor electrodes, acoustic touch sensor structures, resistive touch components, force-based touch sensor structures, a light-based touch sensor, or other suitable touch sensor arrangements. If desired, a display may have a force sensor for gathering force input (e.g., a two-dimensional force sensor may be used in gathering force input on a display). 
     If desired, the sensors may include optical sensors such as optical sensors that emit and detect light, optical touch sensors, optical proximity sensors, and/or other touch sensors and/or proximity sensors, monochromatic and color ambient light sensors, image sensors, fingerprint sensors, ultrasonic sensors, temperature sensors, sensors for measuring three-dimensional non-contact gestures (“air gestures”), pressure sensors, sensors for detecting position, orientation, and/or motion (e.g., accelerometers, magnetic sensors such as compass sensors, gyroscopes, and/or inertial measurement units that contain some or all of these sensors), health sensors, radio-frequency sensors (e.g., sensors that gather position information, three-dimensional radio-frequency images, and/or other information using radar principals or other radio-frequency sensing), depth sensors (e.g., structured light sensors and/or depth sensors based on stereo imaging devices), optical sensors such as self-mixing sensors and light detection and ranging (lidar) sensors that gather time-of-flight measurements, humidity sensors, moisture sensors, gaze tracking sensors, three-dimensional sensors (e.g., time-of-flight image sensors, pairs of two-dimensional image sensors that gather three-dimensional images using binocular vision, three-dimensional structured light sensors that emit an array of infrared light beams or other structured light using arrays of lasers or other light emitters and associated optical components and that capture images of the spots created as the beams illuminate target objects, and/or other three-dimensional image sensors), facial recognition sensors based on three-dimensional image sensors, and/or other sensors. 
     In some configurations, components  18  may include mechanical devices for gathering input (e.g., buttons, joysticks, scrolling wheels, key pads with movable keys, keyboards with movable keys, and other devices for gathering user input). During operation, device  10  may use sensors and/or other input-output devices in components  18  to gather user input (e.g., buttons may be used to gather button press input, touch and/or force sensors overlapping displays can be used for gathering user touch screen input and/or force input, touch pads and/or force sensors may be used in gathering touch and/or force input, microphones may be used for gathering audio input, etc.). The control circuitry of device  10  can then take action based on this gathered information (e.g., by transmitting the information over a wired or wireless path to external equipment, by supplying a user with output using a haptic output device, visual output device, an audio component, or other input-output device in housing  12 , etc.). 
     If desired, electronic device  10  may include a battery or other energy storage device, connector ports for supporting wired communications with ancillary equipment and for receiving wired power, and other circuitry. In some configurations, device  10  may serve as an accessory and/or may include a wired and/or wireless accessory (e.g., a keyboard, computer mouse, remote control, trackpad, etc.). 
     Device  10  may include one or more displays such as display  14 . The displays may, for example, include an organic light-emitting diode display, a liquid crystal display, a display having an array of pixels formed from respective light-emitting diodes (e.g., a pixel array having pixels with light-emitting diodes formed from respective crystalline light-emitting diode dies such as micro-light-emitting diode dies), and/or other displays. The displays may include rigid display structures and/or may be flexible displays. For example, a light-emitting diode display may have a polymer substrate that is sufficiently flexible to be bent. Display  14  may have a rectangular pixel array or a pixel array of another shape for displaying images for a user and may therefore sometimes be referred to as a pixel array. Display  14  may also sometimes be referred to as a display panel, display layer, or pixel layer. Each pixel array in device  10  may be mounted under a transparent housing structure (sometimes referred to as a transparent display cover layer, protective cover layer structures, etc.). 
     In the example of  FIG.  1   , display (pixel array)  14  is mounted under protective layer(s)  32 . Layer  32  (which may be considered to form a portion of the housing of device  10 ), covers front face F of device  10 . Configurations in which opposing rear face R of device  10  and/or sidewall portions of device  10  have transparent structures covering displays and other optical components may also be used. 
     As shown in  FIG.  1   , layer  32  may include image transport layer  16  and display cover layer  30 . Display cover layer  30  serves as a protective outer layer for device  10  and display  14 . Display cover layer  30  may be formed from a layer of glass, clear polymer, crystalline material such as sapphire or other crystalline material, and/or other transparent material. The presence of layer  30  may help protect the outer surface of layer  16  from scratches. If desired, layer  30  may be omitted and layer  16  may serve as a protective display cover layer (e.g., in configurations in which a thin-film protective coating is present on the outer surface of layer  16 , in configurations in which layer  16  is formed from hard material such as glass, and/or in other configurations in which layer  16  is resistant to scratching). A layer of adhesive and/or other structures may be formed between layer  30  and image transport layer  16  and/or may be included elsewhere in the stack of layers on display  14 . 
     During operation, the pixels of display  14  produce image light that passes through image transport layer  16  (sometimes referred to as an image transfer layer). In configurations in which image transport layer  16  is formed from a coherent fiber bundle, image transport layer  16  has optical fibers  16 F. The fibers or other optical structures of image transport layer structures such as image transport layer  16  transport (transfer) light (e.g., image light and/or other light) from one surface (e.g., an input surface of layer  16  that faces display  14 ) to another (e.g., an output surface of layer  16  that faces viewer  28 , who is viewing device  10  in direction  26 ). As the image presented to the input surface of layer  16  is transported to the output surface of layer  16 , the integrity of the image light is preserved. This allows an image produced by an array of pixels to be transferred from an input surface of a first shape at a first location to an output surface with a different shape (e.g., a shape with a footprint that differs from that of the input surface, a shape with a curved cross-sectional profile, a shape with a region of compound curvature, and/or a shape with other desired features). 
     Image transport layer  16  may therefore move the location of an image and may optionally change the shape of the surface on which the image is presented. In effect, viewer  28  will view the image from display  14  as if the image were generated on the output surface of image transport layer  16 . In arrangements in which the image from display  14  is warped (geometrically distorted) by image transport layer  16 , digital pre-distortion techniques or other compensation techniques may be used to ensure that the final image viewed on the output surface of image transport layer  16  has a desired appearance. For example, the image on display  14  may be prewarped so that this prewarped image is warped by an equal and opposite amount upon passing through layer  16 . In this way, the prewarped image is effectively unwarped by passage through layer  16  will not appear distorted on the output surface. 
     In configurations of the type shown in  FIG.  1   , device  10  may have four peripheral edges and a rectangular footprint when viewed in direction  26  or may have other suitable shapes (e.g., a circular outline when viewed in direction  26 ). To help minimize the size of inactive display borders as a user is viewing front face F of device  10  as shown in  FIG.  1   , the shapes of fibers  16 F along the periphery of layer  16  may be deformed outwardly as shown in  FIG.  1   . These fibers  16 F each have an outwardly bent segment that bends away from surface normal n of the center of layer  30  (e.g., away from an axis parallel to the Z axis of  FIG.  1   ) and each have an inwardly bent segment that bends back towards surface normal n to help direct output light towards viewer  28 . 
     The deformed shapes of fibers  16 F (e.g., the bends in fibers  16 F along their lengths) may help distribute image light laterally outwards in the X-Y plane so that the effective size of display  14  is enlarged and the image produced by display  14  covers some or all of the sidewalls of housing  12  or other peripheral portions of device  10  when the image on front face F is being viewed by viewer  28 . For example, the bent shapes of fibers  16 F of  FIG.  1    may help shift portion of the displayed image laterally outward in the X-Y plane along the edges and corners of device  10  to block the edges of device  10  (e.g., the periphery of housing  12 ) from view. This helps make the display of device  10  appear borderless to viewer  28 . In some arrangements, the portions of fibers  16 F at the outermost surface of layer  16  are oriented parallel or nearly parallel with viewing direction  26  and the Z axis of  FIG.  1   , which helps ensure that some or all of the light that has passed through layer  16  will travel in the Z direction and be viewable by viewer  28 . 
       FIG.  2    is a cross-sectional view of a portion of image transport layer  16  in an illustrative configuration in which image transport layer  16  is formed from a coherent fiber bundle. Fibers  16 F for layer  16  may have any suitable configuration. As shown in the example of  FIG.  2   , fibers  16 F may each have a core such as core  16 F- 1 . Cores  16 F- 1  and the other structures of image transport layer  16  (e.g., cladding structures, binder, etc.) may be formed from materials such as polymer, glass, crystalline material such as sapphire, and/or other materials. Some or all of these materials may be transparent. Arrangements in which some of the materials absorb light and/or have non-neutral colors or other light filtering properties may also be used. 
     Fiber cores  16 F- 1  may be formed from transparent material of a first refractive index and may be surrounded by cladding of a second, lower refractive index to promote light guiding in accordance with the principal of total internal reflection. In some arrangements, a single coating layer on cores  16 F- 1  may be used to form the cladding. In other arrangements, two or more coating layers on cores  16 F- 1  may be used to form the cladding. Clad fibers may be held together using binder  16 FB, which serves to fill the interstitial spaces between the clad fibers and join fibers  16 F together. In some configurations, stray light absorbing material may be incorporated into layer  16  (e.g., into some of the cores, cladding, and/or binder). The stray light absorbing material may be, for example, polymer, glass, or other material into which light-absorbing material such as dye and/or pigment has been incorporated. 
     In an illustrative configuration, layer  16  may have inner coating layers  16 F- 2  that are formed directly on the outer surfaces of cores  16 F- 1  and outer coating layers  16 F- 3  that are formed directly on the outer surfaces of layers  16 F- 2 . Additional coating layers (e.g., three or more coating layers) or fewer coating layers (e.g., a single coating layer) may be formed on fiber cores  16 F- 1 , if desired. Stray light-absorbing material may be used in layers  16 F- 2  and/or  16 F- 3  or other coating layer(s) on cores  16 F- 1 . In an illustrative arrangement, layers  16 F- 2  and  16 F- 3 , which may sometimes be referred to as forming first and second cladding portions (or first and second claddings) of the claddings for fiber cores  16 F- 1 , may respectively be formed from transparent material and stray light-absorbing material. Other arrangements may be used, if desired (e.g., arrangements in which stray light absorbing material is incorporated into some or all of binder  16 FB, arrangements in which cores  16 F- 1  are formed directly in binder  16 FB without any intervening cladding, arrangements in which cores  16 F- 1  are covered with layers  16 F- 2  and embedded into binder  16 FB without any additional coating layers such as coating layers  16 F- 3 , arrangements in which cores  16 F- 1  are coated with inner and outer transparent claddings and an interposed intermediate stray-light-absorbing cladding, arrangements in which cores  16 F- 1  are covered with a single stray-light-absorbing cladding, arrangements in which some or all of fibers  16 F are provided with longitudinally extending filaments  16 F- 4  of stray light absorbing material located, for example, on or in any of the cladding layers, etc.). 
     In configuration in which fibers  16 F have claddings formed from two or more separate cladding layers, the cladding layers may have the same index of refraction or the outermost layers may have lower refractive index values (as examples). Binder  16 FB may have a refractive index equal to the refractive index of the cladding material, lower than the refractive index of the cladding material to promote total internal reflection, or higher than the refractive index of the cladding material (as examples). For example, each fiber core  16 F- 1  may have a first index of refraction and the cladding material surrounding that core may have a second index of refraction that is lower than the first index of refraction by an index difference of at least 0.05, at least 0.1, at least 0.15, at least 10%, at least 20%, less than 50%, less than 30%, or other suitable amount. The binder refractive index may be the same as that of some or all of the cladding material or may be lower (or higher) than the lowest refractive index of the cladding by an index difference of at least 0.05, at least 0.1, at least 0.15, at least 10%, at least 20%, less than 50%, less than 30%, or other suitable amount. 
     The diameters of cores  16 F- 1  may be, for example, at least 5 microns, at least 7 microns, at least 8 microns, at least 9 microns, less than 40 microns, less than 17 microns, less than 14 microns, less than 11 microns, or other suitable diameter. Coating layers such as coating layer  16 F- 2  (e.g. a transparent cladding layer) may have thicknesses of at least 0.1 microns, at least 0.4 microns, less than 2.5 microns, less than 0.8 microns, etc. Fibers  16 F (including cores and claddings) may have diameters of at least 6 microns, at least 7 microns, at least 8 microns, at least 9 microns, less than 50 microns, less than 17 microns, less than 14 microns, less than 11 microns, or other suitable diameter. 
     Fibers  16 F may generally extend parallel to each other in image transport layer  16  (e.g., the fibers may run next to each other along the direction of light propagation through the fiber bundle). This allows image light or other light that is presented at the input surface to layer  16  to be conveyed to the output surface of layer  16 . 
     Image transport layers can be used to transport an image from a first (input) surface (e.g., the surface of a pixel array) to a second (output) surface (e.g., a surface in device  10  with compound curvature or other curved and/or planar surface shape) while preserving the integrity of the image. A perspective view of an illustrative corner portion of image transport layer  16  is shown in  FIG.  3   . In the example of  FIG.  3   , layer  16  has edge portions  40  and  42  with surfaces that curve about axes  44  and  46 , respectively. These portions of layer  16  may extend parallel to the straight sides of device  10  (as an example) and are characterized by curved surfaces that can be flattened into a plane without distortion (sometimes referred to as developable surfaces). At the corner of image transport layer  16  of  FIG.  3   , image transport layer  16  has curved surface portions CP with compound curvature (e.g., a surface that can only be flattened into a plane with distortion, sometimes referred to as a surface with Gaussian curvature). In a rectangular layout with curved corners, image transport layer  16  may have four corners with compound curvature. Image transport layers of other shapes (e.g., circular outlines, etc.) may also have surfaces with compound curvature (e.g., dome-shaped surfaces, an edge surface of compound curvature that runs along the circular periphery of a central circular planar region, etc.). When overlapped by layer  30 , the overlapping portions of layer  30  may have corresponding surfaces with compound curvature. When selecting the size and shape of the output surface of layer  16  and therefore the size and shape of the image presented on the output surface, the use of an image transport layer material with compound curvature can provide design flexibility. In general, layer  30  and layer  16  may have planar surfaces and/or surfaces with curved cross-sectional profiles. 
     In some arrangements, device  10  may include support structures such as wearable support structures. This allows device  10  to be worn on a body part of a user (e.g., the user&#39;s wrist, arm, head, leg, or other portion of the user&#39;s body). As an example, device  10  may include a wearable band, such as band  50  of  FIG.  4   . Band  50 , which may sometimes be referred to as a wristband, wrist strap, or wristwatch band, may be formed from polymer, metal, fabric, leather or other natural materials, and/or other material, may have links, may stretch, may be attached to housing  12  in a fixed arrangement, may be detachably coupled to housing  12 , may have a single segment or multiple segments joined by a clasp, and/or may have other features that facilitate the wearing of device  10  on a user&#39;s wrist. 
     Image transport layer  16  may have properties that help ensure satisfactory optical quality and thereby ensure that images are transported from the input surface of layer  16  to the output surface of layer  16  without undesired visual artifacts (e.g., without undesired haziness, non-uniformity, etc.). 
     One attribute that may help ensure satisfactory optical quality relates to fiber alignment. If fibers  16 F are oriented improperly and therefore do not run parallel to each other, image quality may be adversely affected. To help ensure that undesired visual artifacts are not present, fibers  16 F of image transport layer  16  should generally be aligned in parallel with each other within a tight tolerance. Consider, as an example, image transport layer  16  of  FIG.  5   . Image transport layer  16  has multiple fibers  16 F extending along axis Z (e.g., an axis that is perpendicular to the surface normal n of  FIG.  1   , which coincides with the surface normal of display  14 ) between input surface  200  and output surface  202 . Due to manufacturing variations, some of fibers  16 F may not be perfectly aligned with axis Z. For example, one or more of fibers  16 F may be tilted away from surface normal n. As shown in  FIG.  5   , for example, longitudinal axis  204  of fiber  16 FM may be oriented at a non-zero angle A with respect to surface normal n. As a result of this misalignment (non-parallelism) of fiber  16 FM, the core of fiber  16 FM is laterally misaligned (laterally offset) by a distance BD at the input surface of layer  16 . 
     To ensure a desired optical quality for image transport layer  16 , distance BD may be less than one half of the lateral dimensions of the pixels in display  14 . If, as an example, display  14  has an array of pixels that each have lateral dimensions (in the X-Y plane) of 50 microns, it may be desirable to ensure that fibers  16 F have angles A that are sufficiently small to maintain distance BD at a value of less than 25 microns (or less than 30 microns, or other suitable amount). 
     The thickness T of image transport layer  16  can influence the angle A that is to be used. For example, if thickness T is made larger, it will generally be desirable to reduce angle A by a corresponding amount. In an illustrative configuration, fibers  16 F exhibit an angular misalignment (maximum value of A for at least 90% or at least 95% of fibers  16 F) of less than 0.8° when the thickness T of image transport layer  16  is about 1.35 mm, 1.3-1.4 mm, at least 1.2 mm, at least 1.3 mm, at least 1.4 mm, or other suitable value). Other maximum values of angular misalignment (AMAX) may be used in image transport layer  16 , if desired. For example, AMAX (satisfied for at least 90% or at least 95% of fibers  16 F) may have a value of 1.5°, 1.2°, 1.0°, 0.7°, 0.2-0.5°, etc. The maximum lateral deviation of fiber  16 F at input surface  200  (BDMAX) may have any suitable value. For example, BDMAX (satisfied for at least 90% or at least 95% of fibers  16 F) may be 75 microns, 60 microns, 40 microns, 20 microns, etc. The value of BDMAX may be equal to any suitable fraction of the maximum lateral dimension (pixel width PW) of the pixels in display  14 . For example, BDMAX may be 50% of PW, 75% of PW, 30% of PW, 20% of PW, etc. Ensuring that fibers  16 F are sufficiently parallel to maintain (for at least 90% or at least 95% of the fibers in layer  16 ) that BD is less than BDMAX and/or that A is less than AMAX (when layer  16  has a desired thickness T) will help ensure that the image quality for images transported through layer  16  is satisfactory. 
     Another factor that can affect image transport layer quality relates to the fraction of the input and output surfaces that are occupied with binder  16 FB versus fibers  16 F (e.g., cores  16 F- 1 ). As shown in  FIG.  6   , there may be non-zero gaps G between adjacent fibers  16 F in layer  16  due to manufacturing constraints. To help ensure that image transport layer  16  transports images satisfactorily, it may be desirable for at least some of the fibers  16 F in layer  16  to be separated by a gap G from neighboring fibers  16 F that has a value less than GMAX, where GMAX is equal to 1 micron, 0.8 microns, 0.7 microns, 0.6 microns, 0.5 microns, 0.4 microns, or other suitable value. For example, 100% of fibers  16 F may be separated from their nearest neighbors by a gap G of less than 1 micron, 90% of fibers  16 F may be separated from their nearest neighbors by a gap G of less than 0.7 microns, and 50% of fibers  16 F may be separated by a gap G of less than 0.5 microns. 
     If desired, image transport layer material may be formed from filaments of material each of which include multiple fiber cores. Filaments may, as an example, be formed using an extrusion process. Subsequent fusing operations (e.g., sheet fusing operations) can create sheets of filaments that are stacked to form blocks of filaments. The blocks of sheet-stacked filaments can be drawn in a draw tower or other drawing equipment, to reduce their lateral dimensions. The drawing process also helps align fibers  16 F and thereby satisfy desired angular alignment criteria, help reduce the size of gap G and thereby ensure that G is as small as desired, and/or satisfy other criteria that help ensure that a desired optical quality for layer  16  is achieved. 
     During drawing operations, the diameters of fiber cores  16 F- 1  are reduced. The amount that the fiber sizes are reduced in this way can be characterized by a draw ratio DR, defined in equation 1.
 
 DR=D 1 2   /D 2 2   (1)
 
     In equation 1, D 1  is the initial fiber diameter (e.g., the diameter of fiber  16 F or fiber core  16 F- 1 ) before drawing and D 2  is the final fiber diameter (e.g., the diameter of fiber  16 F or core  16 F- 1 ) after drawing operations are complete (e.g., the diameter of fibers  16 F or cores  16 F- 1  in image transport layer  16  of  FIG.  1   ). To ensure satisfactory results, it may be desirable to ensure that draw ratio DR is more than a minimum amount DRMIN. The value of DRMIN may be 1.7. 2.0, 2.5, 3.0, 3.5, 4.0, 5, 7, 9, 10, 12, 14, or 20 (as examples). 
     An illustrative extrusion tool for forming filaments of image transport layer material is shown in  FIG.  7   . As shown in  FIG.  7   , extruder  60  may include hoppers  62  that contain different types of material to be extruded (e.g., different polymers such as binder polymer and fiber core polymer). The material from hoppers  62  may be provided to coextrusion die set  64 . During coextrusion, the material from hoppers  62  is coextruded through extrusion die set  64  and forms one or more elongated extruded members such as extruded filament  66 , which exits extrusion die set  64  in direction  68 . In the example of  FIG.  7   , filament  66  includes multiple fibers  16 F embedded in an elongated strand of binder  16 FB (see, e.g., binder  16 FB of  FIG.  2   ). Fibers  16 F may each have a core  16 F- 1  covered with a coating layer  16 F- 2  (e.g., a transparent cladding) as described in connection with  FIG.  2    or may be other suitable fibers (e.g., fibers having cores with or without cladding, cores with multiple cladding layers, cores and/or coatings with light-absorbing material and/or transparent material, etc.). 
     A single filament  66  is being extruded from extrusion die set  64  in  FIG.  7   . If desired, multiple filaments  66  may be extruded in parallel from die set  64  (e.g., to form bundles of filaments  66  at the output of die set  64 ). In such configurations, filaments  66  may be debundled prior to subsequent operations (e.g., before fusing a layer of filaments  66  together to form a sheet of image transport layer material). 
     Extrusion die set  64  may include one or more layers with channels configured to distribute fiber core material into multiple cores fibers  16 F embedded in binder  16 FB during extrusion. Filaments such as filament  66  may have circular cross-sectional shapes and may contain any suitable number of fiber cores and fibers (e.g., at least 3, at least 10, at least 30, at least 100, at least 500, at least 2500, fewer than 20,000, fewer than 4000, fewer than 500, fewer than 100, and/or other suitable number of fiber cores and fibers  16 F). 
     When it is desired to join the filaments produced by extruder  60  (e.g., extruded strands such as multi-core filament  66  of  FIG.  7    or other elongated polymer members), the filaments may be placed in fusion equipment, which fuses the filaments by applying heat and pressure (e.g., heat and pressure that helps fuse the binder material of the filaments together). In-line fusion tools (e.g., fusers with rollers), laser-fusion equipment, fusion equipment that involves wrapping filaments into channels using computer-controlled equipment that maintains desired angular orientations and tensions computer-controlled, and/or other illustrative fusing tools may be used to fuse filaments together to form image transport layer material. 
     To help ensure satisfactory alignment of filaments  66  with respect to each other during fusion (and therefore ensure satisfactory alignment of fibers  16 F and fiber cores  16 F- 1  in image transport layer  16  and a desired low level of visual artifacts in the coherent fiber bundle), it may be desirable to fuse a single layer of filaments  66  together to form a filament sheet (sometimes referred to as a coherent fiber bundle sheet, a sheet of filaments, a sheet of image transport layer material, etc.). Multiple sheets can then be stacked and fused to form a coherent fiber bundle in which filaments are packed together with a desired filament alignment and density. Such coherent fiber bundle material may sometimes be referred to as sheet-packed coherent fiber bundle material, sheet-packed image transport layer material, sheet-stacked image transport layer material, a sheet-packed coherent fiber bundle, sheet-packed filaments, etc. 
     Sheets of image transport layer material (e.g., sheets of fused filaments) can be formed using equipment of the type shown in  FIG.  8    (as an example).  FIG.  8    is a cross-sectional view of an illustrative fusion tool for producing fused filament sheets. As shown in  FIG.  8   , tool  70  may include filament source  72 . Filament source  72  may include multiple single-filament spools  74 , each of which may dispense a respective multi-core filament  66  (see, e.g., filament  66  of  FIG.  8   ). Each spool  74  may be mounted on a tension controlling dancer arm and may have a respective separate computer-controlled motor. In configurations in which extruder  60  produces bundles of filaments  66 , debundling equipment may be used to separate bundles of filaments  66  into individual filaments  66  each of which may be stored on a respective one of spools  74 . 
     Guide bars  76  may be used to distribute a layer of multiple parallel filaments  66  to one or more aligning wheels  78 . Guide bars  76  may have smooth guide rollers to help reduce friction. Aligning wheels  78  may include springs and/or other tensioning mechanisms and may have a tunable wheel gap to receive and align filaments  66 . As filaments  66  pass through wheels  78 , filaments  66  are aligned so as to form a sheet  66 ′ of aligned unfused filaments of width W. Unfused filament sheet  66 ′ may be passed through a series of interleaved vertically oriented tensioning rods  80  that can be adjusted to increase or decrease friction and therefore control sheet tension. 
     Rollers  82 , which may sometimes be referred to as fusion rollers or pre-fusion rollers, apply heat and/or pressure to the filaments of sheet  66 ′. Heat and pressure may, for example, be applied to form a sheet of joined (e.g., fused) filaments  66 . Sheets may also be formed without sufficient heat and pressure to fuse the filaments together, in which case subsequent fusing operations may be used to fuse filaments  66 . The output of rollers  82 , which may be an unfused sheet of filaments or a partially or fully fused sheet of filaments (filament sheet  66 ″) may be received by a take-up system such as bobbin  84 . Subsequent fusing operations on bobbin  84  or in separate fusing equipment may be used to form a block of sheet-packed coherent fiber bundle material from multiple stacked filament sheets. 
       FIG.  9    is a cross-sectional side view of an illustrative alignment wheel for tool  70 . As shown in  FIG.  9   , alignment wheel  78  may have a pair of parallel disc-shaped wheel members  94  mounted on a common shaft such as shaft  92 . During operation, wheel  78  rotates about axis  90 , which is aligned with shaft  92 . Wheel members  94  may be separated by a gap  96  that is configured to accept only a single layer of filaments  66 . This ensures that filaments  66  will be aligned in a planar array (in a row) to form a planar filament sheet when passing through wheel  78 . 
     Fusion rollers  82  may include mating rollers such as roller  82 M and roller  82 F of  FIG.  10   . Roller  82 F may rotate about axis  102  as roller  82 M rotates in the opposite direction about axis  106 . Roller  82 M protrudes into gap  108  between roller side walls  114  of roller  82 F, so that filaments  66  are compressed between surface  110  of roller  82 F and opposing surface  112  of roller  82 M. By applying heat and/or pressure while filaments  66  pass through rollers  82 F and  82 M, filaments  66  of unfused sheet  66 ′ are joined to form joined (fused) filaments  66  of fused sheet  66 ″ (or these filaments may be partly fused or left unfused for subsequent fusing operations). 
       FIG.  11    is a cross-sectional side view of bobbin  84  of  FIG.  8   . As shown in  FIG.  11   , bobbin  84  may have non-circular take-up wheel  120  that rotates on shaft  126  about rotational axis  128  in direction  130 . Wheel  120  may, for example, have a hexagonal or octagonal shape (as examples). Flat surfaces  122  of wheel  120  allow sheets  66 ″ to be stacked to form blocks of filaments  66 , where filaments  66  are straight and run parallel to each other. For example, a hexagonal shape for wheel  120  may allow six sections of coherent fiber bundle material to be formed each of which contains a respective set of parallel filaments  66 . Bobbin  84  may have guide walls  124  that help laterally align (into and out of the page in the orientation of  FIG.  11   ) the sheets of fused filaments  66  being wound onto wheel  120 . 
     One or more sheets of filaments  66  may be wound onto wheel  120 . In the example of  FIG.  11   , a first filament sheet (sheet  66 A) is being fed in direction  134  onto bobbin  84  while a second filament sheet (sheet  66 B, which may be laterally offset along dimension X by half of a filament diameter with respect to sheet  66 A) is being fed in direction  136  onto bobbin  84 . Pinch rollers  140  and  142 , which may be mounted on movable spring-loaded dancer arms, rotate about respective axes  144  and  146  while pressing inwardly on filaments  66  toward surfaces  122 . In this way, pinch rollers  140  and  142  hold previously wound sheets of filaments  66  flat to prevent buckling and thereby ensure satisfactory winding and alignment of subsequently stacked layers of filaments. 
       FIG.  12    is a cross-sectional side view of bobbin  84  showing how multiple sub-sheets may be wound around wheel  120  into the channels formed between guide walls  124 . In the example of  FIG.  12   , a sheet of filaments on surface  122  of wheel  120  has been formed by winding a first sheet portion  66 P- 1  onto one half of wheel  120  and a second sheet portion  66 P- 2  onto an adjacent second half of wheel  120 . There may be three or more laterally adjacent sheet portions that are wound onto wheel  120  in this way, if desired. Multiple sheet portions may be wound onto wheel  120  simultaneously (to deposit three laterally adjacent sheet portions at the same time), laterally adjacent stack portions may be deposited in series, multiple laterally adjacent sheet portion stacks may be formed one after the next, or other patterns of sheet winding may be used to when stacking sheets of filaments  66  onto wheel  120 . 
     After filaments  66  have been stacked to a desired thickness H (e.g., a height equal to the total sheet width or other suitable size), filaments  66  may be fused under vacuum to form a block of image transport layer material. If desired, the channels of bobbin  84  may receive respective heated dies such as die  150 . Dies such as die  150  may press inwardly in direction  152  against the stacked sheets of filaments  66  so that filaments  66  are compressed between inwardly facing planar surface  154  of die  150  and outwardly facing planar surface  122  of wheel  120 , while being laterally constrained (along dimension X) by the inner surfaces of guide walls  124 . In this type of configuration, bobbin  84  serves as a fusion tool. If desired, sheets  66 ″ may be divided into individual planar sheets (e.g., using a sheet slicing tool that cuts rectangular fused sheets from a continuous strip of fused sheet material at the exit to fusion rollers  84  of  FIG.  8   ). When individual planar sheets of fused fibers are formed in this way, a die with a rectangular cavity (or other suitable cavity shape) may receive a set of stacked planar sheets and may pack and fuse these sheets using heat and pressure to form a block of sheet-packed coherent fiber bundle material. 
     After fusing sheet-stacked filaments  66  to form a block of image transport layer material, this block of material may be processed using a draw tower or other drawing tool, such as illustrative drawing tool (draw tool)  210  of  FIG.  13   . During the drawing process, heat and pressure may be applied so that the block of sheet-stacked fused filaments  66  for image transport layer  16  is forced through drawing tool  210  in direction  212 . This draws out the block of sheet-stacked fused filaments and reduces the overall lateral dimensions of the block (e.g. from lateral size DI before drawing to lateral size DF after drawing). As a result, the lateral dimensions of fibers  16 F and cores  16 F- 1  are reduced to their desired final dimensions. The drawing process also helps align fibers  16 F with the Z axis (e.g., angle A of  FIG.  6    is reduced and lateral offset BD is reduced) and helps reduce the size of gaps G. When using a push-out process in which image transport layer material is forced through tool  210  in this way, both heat and pressure are applied. If desired, tool  210  may be omitted and heat (without pressure) may be applied to layer  16 . To regulate the amount of lateral size reduction of the drawn material (e.g., to regulate lateral size DF), the drawing tool may dynamically adjust the pulling force/speed with which the bottom of the image transport layer material is pulled downwards (in the −Z direction of  FIG.  13   ). 
     In some configurations, the final size (DF) of the drawn image transport layer material is sufficient to form layer  16  of  FIG.  1   , so one or more layers of material may be cut (e.g., sliced with a saw and/or other tools) from the drawn block of material and assembled into devices such as device  10  of  FIG.  1   . In other configurations, the size DF is too small to completely cover the surface of display  14 . In these configurations, the image transport layer block being produced at the output of drawing tool  210 , which may sometimes be referred to as a subblock, may be fused with other subblocks to form a final desired size and shape for layer  16 . This optional subblock fusing process is illustrated in  FIG.  14   . In the example of  FIG.  14   , nine rectangular (e.g. square) subblocks  16 SUB are being fused in fusing tool  214  to form a larger block of image transport layer material. In general, subblocks  14 SUB may have any suitable shape. Following fusing, the image transport layer material may be cut from the fused block to form image transport layer  16  of  FIG.  1   . In general, any suitable number of subblocks of drawn sheet-stacked image transport layer material may be fused together to increase the lateral dimensions of the image transport layer material that is being produced (e.g., at least 4, at least 10, at least 30, at least 100, at least 1000, fewer than 10000, fewer than 500, fewer than 100, fewer than 30, etc.). 
     Illustrative operations in forming drawn sheet-packed coherent fiber bundle material for device  10  are shown in  FIG.  15   . During the operations of block  220 , a tool such as extrusion tool  60  may be used to extrude multi-core filaments such as filament  66 . Each filament may include multiple fibers  16 F (e.g., cores  16 F- 1 , optional coating layer  16 - 2 , etc.) embedded in an elongated strand of binder  16 FB. The diameter of each filament  66  may be, for example, 250 microns, 100 microns, at least 20 microns, at least 60 microns, less than 150 microns, less than 500 microns, less than 1000 microns, or other suitable size. Filaments  66  may be gathered on single-filament spools or may be gathered on spools in multi-filament bundles that are subsequently debundled into individual filaments  66  for source  72  of tool  70  ( FIG.  8   ). To account for subsequent reductions in the diameters of fibers  16 F during drawing, the diameters of fibers  16 F (and cores  16 F- 1 ) may be larger in filaments  66  than desired for the final image transport layer in device  10 . For example, the diameters of fibers  16 F (and/or cores  16 F- 1 ) may be 37 microns, at least 20 microns, at least 30 microns, less than 60 microns, less than 45 microns, or other suitable size that is larger than the diameters of fibers  16 F in layer  16  of device  10 . 
     During the operations of block  222 , filaments  66  are fused or otherwise joined into sheets such as fused sheet  66 ″ (e.g., using fusion rollers  82  of  FIG.  8   ). 
     During the operations of block  224 , alternating laterally offset sheets of filaments  66 A and  66 B are wound onto bobbin  84  and heat and pressure is applied (e.g., using die  150  of  FIG.  12   ) to form a sheet-packed coherent fiber bundle. 
     During the operations of block  226 , the block of image transport layer material formed during the operations of block  224  may be drawn using a drawing tool such as drawing tool  210  of  FIG.  13   . This reduces the lateral dimensions of the block of material. If, as an example, a block has an initial lateral dimension (width) of DI, the block may, following the drawing operation, have a lateral dimension (width) of DF that is less than DI. The draw ratio DR of the fused sheet-stacked coherent fiber bundle (sometimes referred to as the sheet-stacked coherent fiber bundle draw ratio, fused fiber bundle draw ratio, or fiber bundle draw ratio) is equal to DI 2 /DF 2  (which is equal to D 1   2 /D 2   2  of equation 1). During drawing, the lateral dimensions of fibers  16 F are reduced to their desired final values. For example, the initial diameter of fibers  16 F or cores  16 F- 1  may be 37 microns (as an example) and, following the drawing operations of block  226 , the diameters of fibers  16 F or cores  16 F- 1  may be about 10 microns (e.g., the draw ratio DR may be about 14). The thickness of coating layer  16 F- 1  following the drawing operations of block  226  may be, as an example, 0.5 microns. 
     During the operations of block  228 , multiple drawn blocks may optionally be fused together using fusing tool  214  of  FIG.  14   . As an example, the image transport layer material produced during the operations of block  224  may have lateral dimensions in the X and Y dimensions of 50 mm (at least 10 mm, at least 30 mm, less than 250 mm, less than 70 mm, etc.). During the operations of block  228 , multiple subblocks such as these may be fused to form a larger block of image transport layer material that can be used to form layer  16  of  FIG.  1   . The lateral dimensions of layer  16  may be at least 1 cm, at least 5 cm, at least 10 cm, at least 30 cm, less than 1 m, less than 100 cm, less than 50 cm, less than 20 cm, less than 12 cm, less than 6 cm, less than 4 cm, or other suitable value. 
     After forming drawn sheet-packed coherent fiber bundle material during the operations of blocks  220 ,  222 ,  224 ,  226 , and optionally block  228 , the image transport layer material may be optionally deformed (thermally formed) by applying heat and pressure (e.g., in a heated mold). For example, the image transport layer material can be squeezed together so as to deform fibers  16 F and cause fibers  16 F to exhibit one or more bends along their lengths as shown in  FIG.  1   . 
     After forming image transport layer material with desired properties (desired outer dimensions, desired fiber diameters, desired amounts of deformation, etc.), a saw or other equipment may be used to slice a layer of image transport layer material from the deformed image transport layer block. This layer may be shaped using grinding tools, polishing tools, and/or other equipment to form a finished version of image transport layer  16  (see, e.g., layer  16  of  FIG.  1   ). This layer may then be assembled into device  10 . For example, display cover layer  30 , the polished drawn sheet-packed coherent fiber bundle (image transport layer  16 ), display  14 , and other structures may be assembled into housing  12  to form electronic device  10 . For example, layers such as layers  30  and  16  and display  14  may be joined using layers of adhesive. Display  14 , layer  30 , layer  16 , and associated support structures and internal components can be coupled to housing  12  using adhesive, fasteners (e.g., screws), welds, press-fit joints, flexible engagement structures (e.g., springs, clips, etc.), and/or may be mounted to housing  12  using other mounting structures. 
     As described above, one aspect of the present technology is the gathering and use of information such as sensor information. The present disclosure contemplates that in some instances, data may be gathered that includes personal information data that uniquely identifies or can be used to contact or locate a specific person. Such personal information data can include demographic data, location-based data, telephone numbers, email addresses, twitter ID&#39;s, home addresses, data or records relating to a user&#39;s health or level of fitness (e.g., vital signs measurements, medication information, exercise information), date of birth, username, password, biometric information, or any other identifying or personal information. 
     The present disclosure recognizes that the use of such personal information, in the present technology, can be used to the benefit of users. For example, the personal information data can be used to deliver targeted content that is of greater interest to the user. Accordingly, use of such personal information data enables users to calculated control of the delivered content. Further, other uses for personal information data that benefit the user are also contemplated by the present disclosure. For instance, health and fitness data may be used to provide insights into a user&#39;s general wellness, or may be used as positive feedback to individuals using technology to pursue wellness goals. 
     The present disclosure contemplates that the entities responsible for the collection, analysis, disclosure, transfer, storage, or other use of such personal information data will comply with well-established privacy policies and/or privacy practices. In particular, such entities should implement and consistently use privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining personal information data private and secure. Such policies should be easily accessible by users, and should be updated as the collection and/or use of data changes. Personal information from users should be collected for legitimate and reasonable uses of the entity and not shared or sold outside of those legitimate uses. Further, such collection/sharing should occur after receiving the informed consent of the users. Additionally, such entities should consider taking any needed steps for safeguarding and securing access to such personal information data and ensuring that others with access to the personal information data adhere to their privacy policies and procedures. Further, such entities can subject themselves to evaluation by third parties to certify their adherence to widely accepted privacy policies and practices. In addition, policies and practices should be adapted for the particular types of personal information data being collected and/or accessed and adapted to applicable laws and standards, including jurisdiction-specific considerations. For instance, in the United States, collection of or access to certain health data may be governed by federal and/or state laws, such as the Health Insurance Portability and Accountability Act (HIPAA), whereas health data in other countries may be subject to other regulations and policies and should be handled accordingly. Hence different privacy practices should be maintained for different personal data types in each country. 
     Despite the foregoing, the present disclosure also contemplates embodiments in which users selectively block the use of, or access to, personal information data. That is, the present disclosure contemplates that hardware and/or software elements can be provided to prevent or block access to such personal information data. For example, the present technology can be configured to allow users to select to “opt in” or “opt out” of participation in the collection of personal information data during registration for services or anytime thereafter. In another example, users can select not to provide certain types of user data. In yet another example, users can select to limit the length of time user-specific data is maintained. In addition to providing “opt in” and “opt out” options, the present disclosure contemplates providing notifications relating to the access or use of personal information. For instance, a user may be notified upon downloading an application (“app”) that their personal information data will be accessed and then reminded again just before personal information data is accessed by the app. 
     Moreover, it is the intent of the present disclosure that personal information data should be managed and handled in a way to minimize risks of unintentional or unauthorized access or use. Risk can be minimized by limiting the collection of data and deleting data once it is no longer needed. In addition, and when applicable, including in certain health related applications, data de-identification can be used to protect a user&#39;s privacy. De-identification may be facilitated, when appropriate, by removing specific identifiers (e.g., date of birth, etc.), controlling the amount or specificity of data stored (e.g., collecting location data at a city level rather than at an address level), controlling how data is stored (e.g., aggregating data across users), and/or other methods. 
     Therefore, although the present disclosure broadly covers use of information that may include personal information data to implement one or more various disclosed embodiments, the present disclosure also contemplates that the various embodiments can also be implemented without the need for accessing personal information data. That is, the various embodiments of the present technology are not rendered inoperable due to the lack of all or a portion of such personal information data. 
     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: 20210521
Publication Date: 20221213
Grant Date: 20221213
Priority Date: 20200605
Inventors: LIN, WEI
GUPTA, NATHAN K.
GULGUNJE, Prabhakar
MAJUMDAR, SHUBHADITYA
Assignee: APPLE INC
CPC Classifications: [{"code": "G02B6/08", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B6/08", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B6/065", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B6/08", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B6/065", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 84426595