PATENT DOCUMENT

Publication Number: US-9435939-B2
Application Number: US-201213564995-A
Country: US
Kind Code: B2

Title: Displays with coherent fiber bundles

Abstract:
A display may have an array of display pixels that generate an image. A coherent fiber bundle may be mounted on the display pixels. The coherent fiber bundle may have a first surface that is adjacent to the display pixels and a second surface that is visible to a viewer. The coherent fiber bundle may contain fibers that carry light from the first surface to the second surface. The second surface may be planar or may have a central planar region and curved edge regions that run along opposing sides of the central planar region. The fibers may have cross-sectional surface areas with a first aspect ratio on the first surface and a second aspect ratio that is greater than the first aspect ratio on the second surface.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a housing having first and second ends and having first and second sidewalls that run parallel to each other between the first and second ends, wherein the first and second sidewalls have respective first and second top surfaces; 
 display structures that include an array of display pixels interposed between the first and second sidewalls, wherein the array of display pixels are positioned below the respective first and second top surfaces of the first and second sidewalls; and 
 a fiber bundle on the array of display pixels, wherein the fiber bundle has edge portions that overlap the first and second sidewalls, wherein the edge portions are positioned above the respective first and second top surfaces of the first and second sidewalls, wherein the fiber bundle forms a display surface which is viewed by a user, and wherein the display surface is curved in the edge portions of the fiber bundle. 
 
     
     
       2. The electronic device defined in  claim 1  wherein the fiber bundle has a lower surface adjacent to the display structures and an upper surface, wherein the display pixels are configured to display an image, and wherein the fiber bundle is configured to route the image from the lower surface to the upper surface. 
     
     
       3. The display defined in  claim 1  wherein each display pixel provides light to a respective plurality of the fibers in the fiber bundle. 
     
     
       4. The display defined in  claim 1  wherein the fiber bundle comprises a plurality of fibers, wherein each fiber of the plurality of fibers includes an upper surface with a first cross-sectional area and a lower surface with a second cross-sectional area, and wherein the first cross-sectional area has a larger aspect ratio than the second cross-sectional area. 
     
     
       5. The display defined in  claim 1  wherein the fiber bundle includes a central portion with a planar surface. 
     
     
       6. The display defined in  claim 5  wherein the fiber bundle has a first edge portion that runs along one side of the central portion and a second edge portion that runs along an opposing side of the central portion and wherein the first and second edge portions have curved surfaces. 
     
     
       7. The electronic device defined in  claim 1 , wherein the display surface has a planar portion interposed between the edge portions of the fiber bundle. 
     
     
       8. A display, comprising:
 a display layer that includes an array of display pixels; 
 at least one component in an inactive edge portion of the display layer; and 
 a fiber bundle having a first plurality of fibers that overlap only the display pixels and a second plurality of fibers that overlap the display pixels and the inactive edge portion of the display layer, wherein each fiber of the first plurality of fibers has a first surface adjacent the display pixels and a second surface at a display surface of the fiber bundle, wherein each fiber of the first plurality of fibers has a first cross-sectional area on the first surface and a second cross-sectional area on the second surface, wherein the first cross-sectional area has the same aspect ratio as the second cross-sectional area, wherein each fiber of the second plurality of fibers has a third surface adjacent the display pixels and a fourth surface at the display surface of the fiber bundle, wherein each fiber of the second plurality of fibers has a third cross-sectional area on the third surface and a fourth cross-sectional area on the fourth surface, wherein the fourth cross-sectional area has a larger aspect ratio than the third cross-sectional area, wherein the fiber bundle forms a display surface which is viewed by a user, and wherein the display surface is curved in portions of the fiber bundle formed by the second plurality of fibers.

Description:
BACKGROUND 
     This relates to electronic devices and, more particularly, to displays for electronic devices. 
     Electronic devices such as cellular telephones and other portable devices are often provided with displays. In a typical configuration, a rectangular array of display pixels is located in a central active region in the display. An inactive border region surrounds the central active region. Components such as driver circuits can be formed in the inactive border region. The inactive border must generally contain sufficient space for these components, because these components are used in controlling the operation of the display. Nevertheless, excessively large inactive border regions may make a device overly large and may detract from device aesthetics. 
     It would therefore be desirable to be able to provide improved displays for an electronic device. 
     SUMMARY 
     A display may have an array of display pixels that generate an image. The display may be mounted in an electronic device housing in a configuration that minimizes or eliminates the inactive border area surrounding the display. 
     The display may have a coherent fiber bundle that is mounted on the display pixels. The coherent fiber bundle may have a first surface that is adjacent to the display pixels and a second surface that is visible to a viewer. The coherent fiber bundle may contain fibers that carry light from the first surface to the second surface. 
     The second surface may be planar or may have a central planar region and curved edge regions that run along opposing sides of the central planar region. The fibers may have cross-sectional surface areas with a first aspect ratio on the first surface and a second aspect ratio that is greater than the first aspect ratio on the second surface. 
     The display and coherent fiber bundle may have first and second lateral dimensions. The fibers in the coherent fiber bundle may be curved along one of the lateral dimensions and not the other, so as to create an overhang that covers inactive components. 
     Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front perspective view of an illustrative electronic device of the type that may be provided with a display in accordance with an embodiment of the present invention. 
         FIG. 2  is a cross-sectional side view of a display with a coherent fiber bundle in accordance with an embodiment of the present invention. 
         FIG. 3  is a perspective view of a curved edge portion of an illustrative coherent fiber bundle for a display in accordance with an embodiment of the present invention. 
         FIG. 4  is a perspective view of an illustrative coherent fiber bundle in accordance with an embodiment of the present invention. 
         FIG. 5  is a top view of the fiber bundle of  FIG. 4  showing how the fiber surfaces at the top of the fiber bundle may have elongated cross-sectional areas in accordance with an embodiment of the present invention. 
         FIG. 6  is a bottom view of the fiber bundle of  FIG. 4  showing how the fiber surfaces at the bottom of the fiber bundle may have square cross-sectional shapes in accordance with an embodiment of the present invention. 
         FIG. 7  is a perspective view of an edge portion of a coherent fiber bundle in a display in accordance with an embodiment of the present invention. 
         FIG. 8  is an exploded perspective view of an electronic device having a display with a coherent fiber bundle in accordance with an embodiment of the present invention. 
         FIG. 9  is a cross-sectional side view of a coherent fiber bundle in which fibers have cross-sectional areas with varying aspect ratios in accordance with an embodiment of the present invention. 
         FIG. 10  is a top view of an illustrative display pixel showing how multiple fibers may overlap each pixel in a display in accordance with an embodiment of the present invention. 
         FIG. 11  is a cross-sectional side view of a display having multiple adjacent coherent fiber bundles in accordance with an embodiment of the present invention. 
         FIG. 12  is a diagram of illustrative equipment that may be used in forming a coherent fiber bundle having fibers with cross-sectional areas of varying aspect ratios in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     An illustrative electronic device of the type that may be provided with a display is shown in  FIG. 1 . Device  10  of  FIG. 1  may be a handheld device such as a cellular telephone or media player, a tablet computer, a notebook computer, other portable computing equipment, a wearable or miniature device such as a wristwatch or pendant device, a television, a computer monitor, or other electronic equipment. 
     As shown in  FIG. 1 , electronic device  10  may include a display such as display  14 . Display  14  may be a touch screen that incorporates a layer of conductive capacitive touch sensor electrodes or other touch sensor components or may be a display that is not touch-sensitive. 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 electrowetting display pixels, or display pixels based on other display technologies. 
     Display  14  may be protected using an optional display cover layer such as a layer of transparent glass or clear plastic. Openings may be formed in the display cover layer. For example, an opening may be formed in the display cover layer to accommodate a button such as button  16  and an opening such as opening  18  may be used to form a speaker port. Device configurations without openings in display  14  may also be used for device  10 . 
     Device  10  may have a housing such as housing  12 . Housing  12 , which may sometimes be referred to as an enclosure or case, 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. 
     Housing  12  may be formed using a unibody configuration in which some or all of housing  12  is machined or molded as a single structure or may be formed using multiple structures (e.g., an internal frame structure, one or more structures that form exterior housing surfaces, etc.). 
     Display  14  may be characterized by an active region such as rectangular active region  20  (the area inside rectangular dotted line  20 ). Images may be displayed in the active region using an associated array of display pixels (e.g., backlight LCD cells, organic light-emitting diode cells, or other image-producing display elements). The rectangular active region  20  may be surrounded by an inactive region such as inactive border region  22 . 
     Inactive border region  22  may be characterized by a minimum width W (e.g., along the left and right edges of display  14  of  FIG. 1 ). To minimize the size of width W, display  14  may be provided with a coherent fiber bundle that expands the size of the display along the edges of device  10  (e.g., in lateral dimension X). The size of width W may be reduced to less than 2 mm, less than 1 mm, less than 0.5 mm, less than 0.2 mm, or may be reduced to zero or a negligible amount. 
       FIG. 2  is a cross-sectional side view of display  14  taken along line  26  and viewed in direction  28 . As shown in  FIG. 2 , display  14  may include display structures  30 . Display structures  30  may be formed from organic light-emitting diode structures, backlit electrophoretic display structures, backlight electrowetting display structures, or backlight liquid crystal display (LCD) display layers (as examples). For example, display structures  30  may include liquid crystal display structures such as a color filter layer, a thin-film transistor layer, and a layer of liquid crystal material that is formed between the color filter layer and the thin-film transistor layer. 
     Display structures  30  may include an array of display pixels  32 . When controlled using display driver circuitry, the array of display pixels  32  may be used in presenting images to a viewer such as viewer  42 , who is viewing display  14  in direction  40 . Circuitry such as display driver circuitry and other display components that do not display images may be located in inactive edge region  36  of display  14 . Region  36  may include, for example, a bead of sealant interposed between a color filter layer and a thin-film transistor layer, thin-film transistors (e.g., gate driver circuitry), and traces for providing display control signals to display pixels  32  (shown illustratively as structures  38 ). 
     Coherent fiber bundle  44  may have multiple fibers that convey light  34  from pixels  32  vertically upwards to display surface  46 . Fiber bundle  44  is coherent in that images that are created by display pixels  34  are not scrambled or otherwise disturbed when passing through fiber bundle  44 . Viewer  42  may therefore view satisfactory images on surface  46 , including central portion C and edge portions E. 
     In central portion C of coherent fiber bundle  44 , light  34 B from display pixels  32 B may be conveyed to surface  46  through fibers that extend parallel to one another along dimension Z. In edge regions E, coherent fiber bundle  44  may include fibers that guide light  34 A from display pixels  32 A to surface  46  along curved paths. The use of curved paths for the fibers in bundle  44  in edge regions E allows edge regions E to overlap inactive display regions  36  when display  14  is viewed in direction  40  by viewer  42 , thereby presenting viewer  42  with a borderless display (i.e., a display in which inactive region width W of  FIG. 1  is zero with respect to dimension Y and, if desired, with respect to dimension X). 
     As shown in  FIG. 2 , for example, the curved nature of the fibers in portion E of coherent fiber bundle  44  may create an overhang that extends by an amount XD over inactive region  36 . The amount XD may be sufficient to narrow the size of the inactive display region (region  22  of  FIG. 1 ) in display  14  or may, as shown in  FIG. 2 , may be sufficient to completely cover inactive regions  36  so that display  14  is effectively borderless in dimension Y and, if desired, in dimension X. 
     Coherent fiber bundle  44  may be formed from a set of parallel fibers. The fibers may be formed from a clear material such as glass. Each fiber may have a core and a cladding. The index of refraction of the core may be greater than the index of refraction of the cladding to promote total internal reflection. Fibers may be heated and manipulated using stretching equipment and/or rollers or other pressing equipment. Glass particles or other binders may be used in binding individual fibers together to form fiber bundle  44 . Using fabrication techniques such as these, the fibers in fiber bundle  44  may be positioned so as to follow straight paths (i.e., straight paths such as paths  34 B of  FIG. 2 ) or curved paths such as curved path  34 A of  FIG. 2 . 
     The shape of surface  46  may be planar or may have a curved shape (e.g., along the opposing left and right edges of the display), as illustrated by dotted line  46 ′ of  FIG. 2 . 
       FIG. 3  is a perspective view of a portion of coherent fiber bundle  44  in a configuration in which fibers  44 F have been shaped to form a curved surface such as surface  46 ′. Fibers  44 F may have a circular cross-sectional shape on surface  46 ′ (as an example). In shapes such as circular or square shapes, a shape may be said to have a 1:1 aspect ratio (width versus length). In elongated shapes such as rectangles or ovals, the aspect ratio of the shape may be different (e.g., 1:3, etc.). In fiber bundle  44 , the aspect ratio of the area of the fibers may be constant or may change between the upper and lower surfaces of the bundle. 
       FIG. 4  is a perspective view of portion of coherent fiber bundle  44  in a configuration in which fibers  44 F have been shaped to form a flat surface such as surface  46 ′. 
       FIG. 5  is a top view of fiber bundle  44  showing fibers  44 F on top surface  46  when viewed in direction  40  of  FIG. 4 . As shown in  FIG. 5 , coherent fiber bundle upper surface  46  may have fibers  44 F having rectangular areas with an aspect ratio of about 4:1 (e.g., an aspect ratio greater than 1.5:1, greater than 2:1, greater than 3:1, or greater than 5:1). As shown in  FIG. 6 , coherent fiber bundle lower surface  52  may have fibers  44 F that have square areas or areas of other shapes with a 1:1 aspect ratio (e.g., an aspect ratio less than 1.5:1, less than 2:1, less than 3:1, or less than 5:1). By using fiber bundles with changing aspect ratios, it is possible to transition between a relatively smaller area such as lower surface area  52  of coherent bundle  44  of  FIG. 4  to a relatively larger area such as upper surface area  46  of coherent bundle  44  of  FIG. 4  within edge region E, while retaining a planar shape to upper surface  46 . This allows display  14  to have a planar surface that extends from edge to edge. 
     As shown in the perspective view of  FIG. 7 , in portions E, fibers  44 F′ may have a rectangular cross-sectional area (i.e., elongated aspect ratios), whereas in central region C, the surfaces of fibers  44 F″ may have 1:1 aspect ratios (e.g., aspect ratios that are less than the aspect ratios of fibers  44 F′). 
       FIG. 8  is a perspective view of device  10  showing how display  14  may have edges E that extend laterally in dimension Y so as to create overhang XD in dimension Y. This allows display  14  to be borderless or nearly borderless in dimension Y. Device housing  12  may have sidewall edges  12 ′ that run parallel to each along longitudinal axis LG of device  10  between lower end  102  and upper end  100  of device  10 . If desired, left and right edges  54  may overlap edges  12 ′ of housing  12  in device  10 , so that display  14  appears borderless in dimension Y. 
     In dimension X, inactive portions  36  of display structures  30  (e.g., a thin-film transistor layer and/or other layers in display  14 ) may be used to accommodate components  38  such as driver integrated circuits, flexible printed circuit cable attachment patterns, or traces for distributing display control signals to transistors in the active portion of the display. Inactive portions  36  may also extend under edges E of fiber bundle  44 . In this portion of inactive portions  36 , thin-film transistor circuitry (e.g., for gate driver circuits), liquid crystal display sealant beads, and other inactive structures may be formed on display layers  30 . 
       FIG. 9  is a cross-sectional side view of coherent fiber bundle  44  showing how multiple fibers  44 F may be associated with each display pixel  32 . In regions such as edge regions E 1 , E 2 , and E 3 , the shape of the surface area of each fiber  44 F may be elongated (with an aspect ratio of 2:1 or more, as an example), as shown in  FIG. 5 . Regions E 1 , E 2 , and E 3  are associated respectively with display pixels  32 - 1 ,  32 - 2 , and  32 - 3 . For example, the light produced by pixel  32 - 3  may be displayed in region E 3  after being conveyed through the fibers  44 F that overlap pixel  32 - 3 . The use of larger aspect ratios for the surfaces of fibers  44 F in regions E 1 , E 2 , and E 3  allows upper surface  46  of display  14  to be planar (if desired). In central regions such as C 1  and C 2 , fibers  44 F may extend vertically upwards. There is some loss of display resolution in regions E 1 , E 2 , and E 3  relative to in regions C 1  and C 2 , but the information displayed in edge regions E 1 , E 2 , and E 3  of display  14  may often contain solid colors or other low-information-content material, where the loss of resolution is immaterial to the performance of display  14 . 
       FIG. 10  is a top view of an illustrative display pixel showing how multiple fibers  44 F may be associated with a single pixel. Each display pixel such as display pixel  32  of  FIG. 10  may be associated with about N×N fibers  44 F. As an example, a set of about 10-50 fibers  44 F may be used to route light from each display pixel to the surface of coherent fiber bundle  46 . Configurations in which a single fiber is associated with each display pixel or in which other numbers of fibers are associated with each display pixel may also be used, if desired. 
     As shown in  FIG. 11 , multiple coherent fiber bundles such as bundles  44 A,  44 B, and  44 C may be mounted adjacent to each other so that their peripheral edges (e.g., their left and right edges) may mate with each other, forming surface  46  of display  14  from multiple bundle surfaces. Inactive regions  36  on display layer  30  may be used for mounting components  38 . 
     A system for forming a coherent fiber bundle of the type shown in  FIG. 4  is shown in  FIG. 12 . Initially, fiber bundle  44 X may have fibers  44 F that are aligned along dimension  70 . Heated rollers  56  may be used to constrain fiber bundle  44 X with respect to dimension  72 . Rollers  58  and  60  may be used to squeeze fiber bundle  44 X in dimension  74 . For example, roller  60  may be moved along directions  64  between position  62  and the position shown in  FIG. 12  in order to apply pressure to fiber bundle  44 X as fiber bundle  44 X is moved through the roller system in direction  66 . Upon exiting the rollers in direction  78 , fiber bundle  44  may have the appearance shown in the bottom portion of  FIG. 12  in which upper surface  46  has a larger width WL than lower surface width WS (see, e.g., fiber bundle  44  of  FIG. 4 ). 
     The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20120802
Publication Date: 20160906
Grant Date: 20160906
Priority Date: 20120802
Inventors: YANG TSENG-MAU
PREST CHRISTOPHER D.
MEMERING DALE N.
Assignee: APPLE INC
CPC Classifications: [{"code": "G02F1/3137", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B6/08", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B6/08", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B6/0078", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B2006/12145", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/3137", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B6/0078", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B6/08", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F2001/0142", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B2006/12145", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/0142", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 50025550