WO2018194973A1

WO2018194973A1 - Light coupler

Info

Publication number: WO2018194973A1
Application number: PCT/US2018/027775
Authority: WO
Inventors: Aleksandra Boskovic; Sergey Anatol'evich KUCHINSKY; Shenping Li
Original assignee: Corning Inc
Current assignee: Corning Inc
Priority date: 2017-04-21
Filing date: 2018-04-16
Publication date: 2018-10-25
Anticipated expiration: 2019-10-21
Also published as: CN110785606A; JP2020518098A; TW201903444A; KR20190138685A

Abstract

A back light unit may include a light guide plate and a light coupler including a plurality of concentric waveguides. Each of the plurality of concentric waveguides may include an inner surface and an outer surface extending from a first edge of the waveguide to a second edge of the waveguide along an arcuate path defining a radius of the waveguide. The first edge of each of the plurality of concentric waveguides may face an outer edge of the light guide plate. The back light unit may include a light source facing the second edge of each of the plurality of concentric waveguides. The back light unit may also include a second light coupler positioned between the light source and the first light coupler. A light coupler including a plurality of concentric waveguides may also be provided.

Description

LIGHT COUPLER

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of priority under 35 U. S.C. § 119 of U. S. Provisional Application Serial No. 62/488,368 filed on April 21 , 2017, the content of which is relied upon and incorporated herein by reference in its entirety.

FIELD

[0002] The present disclosure relates generally to a light coupler, and more particularly, to a light coupler including a plurality of concentric waveguides.

BACKGROUND

[0003] It is known to illuminate a display panel of an electronic display with a back light unit. It is also known to illuminate a light guide plate and a waveguide with a light source.

SUMMARY

[0004] The following presents a simplified summary of the disclosure in order to provide a basic understanding of some exemplary embodiments described in the detailed description.

[0005] In some embodiments, a light coupler may include a plurality of concentric waveguides. Each of the plurality of concentric waveguides may include an inner surface and an outer surface extending from a first edge of the waveguide to a second edge of the waveguide along an arcuate path defining a radius of the waveguide.

[0006] In some embodiments, a back light unit may include the light coupler, and the first edge of each of the plurality of concentric waveguides may face an outer edge of a light guide plate.

[0007] In some embodiments, a back light unit may include a light guide plate and a light coupler comprising a plurality of concentric waveguides. Each of the plurality of concentric waveguides may include an inner surface and an outer surface extending from a first edge of the waveguide to a second edge of the waveguide along an arcuate path defining a radius of the waveguide. The first edge of each of the plurality of concentric waveguides may face an outer edge of the light guide plate. The back light unit may include a light source facing the second edge of each of the plurality of concentric waveguides.

[0008] In some embodiments, the inner surface and the outer surface of each of the plurality of concentric waveguides may extend equidistant from each other along the arcuate path without diverging or converging.

[0009] In some embodiments, the radius of each of the plurality of concentric waveguides may be constant.

[0010] In some embodiments, the light coupler may further include a gap defining a distance between adjacent waveguides.

[0011] In some embodiments, the gap may include at least one of air and a material having a refractive index about 0.2 less than a refractive index of a material of the adjacent waveguides.

[0012] In some embodiments, the gap may extend along the entire arcuate path between adjacent waveguides.

[0013] In some embodiments, the distance may be from about 1 micron to about 10 microns.

[0014] In some embodiments, the distance may be constant.

[0015] In some embodiments, each of the plurality of concentric waveguides may include a rectangular cross-sectional profile taken perpendicular to the arcuate path.

[0016] In some embodiments, the rectangular cross-sectional profile may be constant along the entire arcuate path.

[0017] In some embodiments, a central angle defining an arc length between the first edge and the second edge of each of the plurality of concentric waveguides may be from about 90° to about 180°.

[0018] In some embodiments, the central angle may be about 180°.

[0019] In some embodiments, a thickness of each of the plurality of concentric waveguides defined between the inner surface and the outer surface may be from about 0.2 mm to about 2.0 mm. [0020] In some embodiments, the radius of an innermost waveguide of the plurality of concentric waveguides may be from about 1 mm to about 10 mm.

[0021] In some embodiments, the radius of the innermost waveguide may be about 1 mm.

[0022] In some embodiments, a back light unit may include a light guide plate including a first major surface and a second major surface, and a first light coupler including a plurality of concentric waveguides. Each of the plurality of concentric waveguides may include an inner surface and an outer surface extending from a first edge of the waveguide to a second edge of the waveguide along an arcuate path defining a radius of the waveguide. The first edge of each of the plurality of concentric waveguides may face an outer edge of the light guide plate. The back light unit may include a second light coupler including a first surface coupled to the second edge of each of the plurality of concentric waveguides and a second surface coupled to a light source. A height of a light emitting region of the light source may greater than a thickness of the light guide plate defined between the first major surface of the light guide plate and the second major surface of the light guide plate.

[0023] In some embodiments, a thickness of the first light coupler defined between the inner surface of an innermost waveguide of the plurality of concentric waveguides and the outer surface of an outermost waveguide of the plurality of concentric waveguides may be less than the height of the light emitting region of the light source.

[0024] In some embodiments, the thickness of the first light coupler may be approximately equal to the thickness of the light guide plate.

[0025] In some embodiments, an electronic display may include the back light unit oriented to face a major surface of a display panel.

[0026] The above embodiments are exemplary and may be provided alone or in any combination with any one or more embodiments provided herein without departing from the scope of the disclosure. Moreover, it is to be understood that both the foregoing general description and the following detailed description present embodiments of the present disclosure, and are intended to provide an overview or framework for understanding the nature and character of the embodiments as they are described and claimed. The accompanying drawings are included to provide a further understanding of the embodiments, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the disclosure, and together with the description, serve to explain the principles and operations thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] These and other features, embodiments, and advantages of the present disclosure may be further understood when read with reference to the accompanying drawings:

[0028] FIG. 1 illustrates a schematic plan view of an exemplary electronic display in accordance with embodiments of the disclosure;

[0029] FIG. 2 shows a cross-sectional view of the exemplary electronic display along line 2-2 of FIG. 1 including an exemplary back light unit in accordance with embodiments of the disclosure.

[0030] FIG. 3 shows an enlarged view of a region of the back light unit identified by numeral 3 of FIG. 2 including a first light coupler including a plurality of concentric waveguides in accordance with embodiments of the disclosure;

[0031] FIG. 4 shows a cross-sectional view of the first light coupler along line 4-4 of FIG. 3 in accordance with embodiments of the disclosure;

[0032] FIG. 5 illustrates an exemplary embodiment of the region of the back light unit of FIG. 3 including a second light coupler positioned between the first light coupler and a light source in accordance with embodiments of the disclosure;

[0033] FIG. 6 illustrates another exemplary embodiment of the region of the back light unit of FIG. 3 including an alternative second light coupler positioned between the first light coupler and a light source in accordance with embodiments of the disclosure;

[0034] FIG. 7 shows a plan view of the alternative second light coupler along line 7-7 of FIG. 6;

[0035] FIG. 8 illustrates an exemplary plot for waveguides including different thicknesses in accordance with embodiments of the disclosure, where the vertical or "Y" axis represents optical loss in decibels (dB) and the horizontal or "X" axis represents radius of the waveguide in millimeters (mm); and

[0036] FIG. 9 illustrates an exemplary plot for waveguides including different thicknesses in accordance with embodiments of the disclosure, where the vertical or "Y" axis represents optical transmission in percent (%) and the horizontal or "X" axis represents radius of the waveguide in millimeters (mm).

DETAILED DESCRIPTION

[0037] Features will now be described more fully hereinafter with reference to the accompanying drawings in which exemplary embodiments of the disclosure are shown. Whenever possible, the same reference numerals are used throughout the drawings to refer to the same or like parts. However, this disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

[0038] FIG. 1 illustrates a plan view of an exemplary electronic display 100 in accordance with embodiments of the disclosure. In some embodiments, the electronic display 100 may include a display panel 110 positioned within a housing 105. In some embodiments, the housing 105 may protect the display panel 110 and provide a structure by which the electronic display 100 may be mounted, held, touched, contacted, etc. by a user and/or environment in which the electronic display 100 may be employed. In some embodiments, the housing 105 may include a bezel 115 defining an opening 116 laterally circumscribing at least a portion of a first major surface 111 of the display panel 110. The bezel 115 may include a bezel width "W" defined between the opening 116 and an outer surface 106 of the housing 105. In some embodiments, as discussed more fully below, features of the disclosure may provide a bezel width "W" that is reduced (e.g., narrower) than, for example, bezel widths of other electronic displays. Additionally, in some embodiments, features of the disclosure may eliminate the bezel width "W" and provide, for example, a bezel- free electronic display 100. Likewise, as discussed more fully below, features of the disclosure may provide a housing dimension "D" (e.g., depth, thickness) that is reduced (e.g., thinner) than, for example, a housing dimension (e.g., depth, thickness) of other electronic displays. In some embodiments, consumer and market demands may desire an electronic display 100 including a bezel 115 that includes a narrow bezel width "W", a bezel-free electronic display 100, and/or a housing 105 that includes a thin housing dimension "D" for one or more of aesthetic, mechanical, and functional reasons.

[0039] Additionally, although the opening 116 is illustrated as rectangular, it is to be understood that, in some embodiments, the opening 116 may include a circular, oval, polygonal, etc. profile without departing from the scope of the disclosure. Similarly, although the bezel 115 and the outer surface 106 of the housing 105 are illustrated as planar, it is to be understood that, in some embodiments, at least one of the bezel 115 and the outer surface 106 may include non-planar features and/or a non-planar profile without departing from the scope of the disclosure. Moreover, although the display panel 110 is illustrated as planar, it is to be understood that, in some embodiments, the display panel 110 may include non-planar features and/or a non-planar (e.g., curved) profile without departing from the scope of the disclosure. In some embodiments, the bezel width "W" may be constant and the bezel 115 may extend around an entire perimeter of at least a portion of the first major surface 111 of the display panel 110. Alternatively, in some embodiments, the bezel width "W" may vary and may, therefore, include relatively narrower and wider portions. In some embodiments, the bezel 115 may extend around a portion of a perimeter of at least a portion of the first major surface 111. Likewise, in some embodiments, the housing dimension "D" may be constant for the entire electronic display 100. Alternatively, in some embodiments, the housing dimension "D" may vary and may, therefore, include thicker and thinner portions at one or more locations of the electronic display 100.

[0040] FIG. 2, shows a cross-sectional view of the electronic display 100 along line 2-2 of FIG. 1. In some embodiments, the electronic display 100 may include a back light unit 200 oriented to face, for example, a second major surface 112 of the display panel 110. In some embodiments, the first major surface 111 of the display panel 110 may face outward away from the back light unit 200, and the back light unit 200 may illuminate the display panel 110 by providing light from the back light unit 200 to the second major surface 112 of the display panel 110. In some embodiments, the electronic display 100 may be employed as a computer monitor, television monitor, portable display for a cellular phone, tablet, etc. , where the display panel 110 may provide an electronic image (e.g. , text, picture, video, etc.) and the back light unit 200 may illuminate the display panel 110 including the electronic image provided on the display panel 110. For example, in some embodiments, the display panel 110 may include an LCD panel oriented to produce the electronic image which, when illuminated from behind by the back light unit 200, may then be viewed by a user facing the first major surface 111 of the display panel 110.

[0041] In some embodiments, the back light unit 200 may include a light guide plate 210 including a first major surface 211 and a second major surface 212. The light guide plate 210 may include an outer edge 213 extending from the first major surface 211 to the second major surface 212 and circumscribing the first major surface 211 and the second major surface 212. As discussed more fully below, in some embodiments, the back light unit 200 may include a first light coupler 220, 221 and a light source 225, 226. In some embodiments, the first light coupler 220, 221 (including one or more features of the first light coupler 220, 221) may be provided alone and may therefore be considered complete. Alternatively, in some embodiments, the first light coupler 220, 221 may be provided in combination with one or more features of the disclosure and may be incorporated, for example, as a component of the back light unit 200 and the electronic display 100. Additionally, in some embodiments one first light coupler (e.g., first light coupler 220) and one light source (e.g., light source 225) may be provided; however, in some embodiments, more than one first light coupler and more than one light source may be provided, without departing from the scope of the disclosure.

[0042] For example, in some embodiments, a single first light coupler 220 may be provided along one side of the outer edge 213 of the light guide plate 210 without providing additional light couplers. In some embodiments, employing a single first light coupler 220 may reduce the number of components of the back light unit 200, thereby simplifying the cost and time associated with manufacturing the back light unit 200 as well as reducing the size of the back light unit 200. For example, in some embodiments, employing a single first light coupler 220 may reduce at least one of the bezel width "W" and the housing dimension "D" by allowing the housing dimension "D" (e.g., opposite the location of the first light coupler 220) to be reduced as there is no light coupler to be accommodated at the location when employing a single first light coupler 220. Thus, it is to be understood, that features described with respect to the first light coupler 220 and the light source 225 may be applied, either alone or in combination and in a same or similar manner, to the first light coupler 221 and the light source 226 as well as to other first light couplers and other light sources not explicitly disclosed, without departing from the scope of the disclosure.

[0043] Additionally, in some embodiments, the electronic display 100 may include one or more optical components (not shown) including, but not limited to, reflectors, filters, films, diffusers, etc. Likewise, in some embodiments, the electronic display 100 may include one or more additional electronic components (shown generally as components 230) including, but not limited to, transducers, circuits, receivers, transmitters, power supplies, batteries, memory storage, sensors, heat sinks, etc. integrated with and at least one of mechanically and electrically connected to the electronic display 100. For example, in some embodiments, one or more of the components 230 may provide functionality to enable a user to interact with and control one or more features of the electronic display 100. Accordingly, it is to be understood that, unless otherwise noted, features of the electronic display 100 may be employed in a variety of applications including, but not limited to, the particular applications provided in the present disclosure as exemplary embodiments as well as other applications not explicitly disclosed without departing from the scope of the disclosure.

[0044] FIG. 3 shows an enlarged view of a region of the back light unit 200 identified by numeral 3 of FIG. 2 with features of the housing 105 as well as the cross-sectional hatch patterns removed for clarity. In some embodiments, the first light coupler 220 may include a plurality of concentric waveguides 300a, 300b, 300c. Although three concentric waveguides 300a, 300b, 300c are shown, it is to be understood that, in some embodiments, two, four, five, or more concentric waveguides may be provided, without departing from the scope of the disclosure. Additionally, in some embodiments, the first light coupler 220 may include a single waveguide. In some embodiments, each waveguide 300a, 300b, 300c (i.e., each waveguide 300a, 300b, 300c of the plurality of concentric waveguides, i.e., each of the plurality of concentric waveguides 300a, 300b, 300c) may include an inner surface 301a, 301b, 301c and an outer surface 302a, 302b, 302c. The inner surface 301a, 301b, 301c and the outer surface 302a, 302b, 302c may extend from a first edge 303a, 303b, 303c of the waveguide 300a, 300b, 300c to a second edge 304a, 304b, 304c of the waveguide 300a, 300b, 300c along an arcuate path 305a, 305b, 305c defining a radius Ra, Rb, Rc of the waveguide 300a, 300b, 300c. For example, the term "concentric waveguides" is intended to mean that each waveguide 300a, 300b, 300c of the plurality of concentric waveguides may share the same center 311 (e.g., center point, central axis) defined relative to a bent (e.g., curved, circular, partial-circular, elliptical, partial-elliptical) profile of each waveguide 300a, 300b, 300c.

[0045] In some embodiments, the radius Ra, Rb, Rc may correspond to a radial dimension from the center 311 to a location on the inner surface 301a, 301b, 301c of the waveguide 300a, 300b, 300c. Likewise, in some embodiments, the radius Ra, Rb, Rc may correspond to a radial dimension from the center 311 to a location on the outer surface 302a, 302b, 302c of the waveguide 300a, 300b, 300c. Moreover, in some embodiments, the radius Ra, Rb, Rc may correspond to a radial dimension from the center 311 to a radial location defined between the inner surface 301a, 301b, 301c and the outer surface 302a, 302b, 302c. For purposes of the disclosure, unless otherwise noted, the radius Ra, Rb, Rc is intended to refer to a radial dimension from the center 311 to a radial midpoint location defined equidistant between the inner surface 301a, 301b, 301c and the outer surface 302a, 302b, 302c, as shown, for example, in FIGS. 3, 5, and 6. [0046] In some embodiments, the inner surface 301a, 301b, 301c and the outer surface 302a, 302b, 302c may extend in the same direction (e. g., along the arcuate path 305a, 305b, 305c) without diverging or converging. For example, in some embodiments, the inner surface 301a, 301b, 301c and the outer surface 302a, 302b, 302c may extend equidistant from each other along the arcuate path 305a, 305b, 305c without diverging or converging. Additionally, in some embodiments, relative to each other, the inner surface 301a, 301b, 301c and the outer surface 302a, 302b, 302c may be equidistant at all points (e.g., relative to a radial location along the radius Ra, Rb, Rc) along the arcuate path 305a, 305b, 305c and, therefore, over the entire central angle 310. Additionally, in some embodiments, relative to each other, the inner surface 301a, 301b, 301c and the outer surface 302a, 302b, 302c may be equidistant at all points (e.g., relative to a radial location along the radius Ra, Rb, Rc) at all cross-sections parallel to the section 2-2 of FIG. 1 over the entire central angle 310. Moreover, in some embodiments, the radius Ra, Rb, Rc of each waveguide 300a, 300b, 300c of the plurality of concentric waveguides may be constant. For example, in some embodiments, a central angle 310 defining an arc length between the first edge 303a, 303b, 303c and the second edge 304a, 304b, 304c of each waveguide 300a, 300b, 300c may be from about 90° to about 180°. In some embodiments, the radius Ra, Rb, Rc may be constant over the entire central angle 310 where the radius Ra, Rb, Rc is the same value throughout the entire central angle 310. In some embodiments, the radius Ra, Rb, Rc may optionally be constant (e.g. , the same value) at all cross-sections parallel to the section 2-2 of FIG. 1 over the entire central angle 310. Alternatively, in some embodiments, one or more radii Ra, Rb, Rc may vary at one or more locations over the central angle 310 and/or may vary at one or more locations at one or more cross-sections parallel to the section 2-2 of FIG. 1. In some embodiments, the central angle 310 may be about 180°, and each waveguide 300a, 300b, 300c may, therefore, define a semi-circular profile (e.g., corresponding to constant radii Ra, Rb, Rc) or a semi-elliptical profile (e.g. , corresponding to varying radii Ra, Rb, Rc). Thus, unless otherwise noted, it is to be understood that although illustrated as a plurality of semi-circular concentric waveguides 300a, 300b, 300c, in some embodiments, the first light coupler 220 may include a plurality of concentric waveguides 300a, 300b, 300c defining various profiles in accordance with embodiments of the disclosure without departing from the scope of the disclosure.

[0047] As mentioned above, in some embodiments, the first light coupler 220 may include a constant cross-sectional profile, for example, as viewed along line 2-2 of FIG. 1. In further embodiments, as mentioned above, a cross-sectional profile of the first light coupler 220 may vary relative to a location defined along at least one of a width and a length of the light guide plate 210. In some embodiments, if the cross- sectional profile of the first light coupler 220 as viewed along line 2-2 of FIG. 1 is constant, the first light coupler 220 including the plurality of concentric waveguides 300a, 300b, 300c may be represented as a projection of the cross-sectional profile illustrated, for example, in FIG. 3, projected in a direction along an axis perpendicular to the plane defining the cross-section. For example, in some embodiments, the axis may be linear, and the first light coupler 220 may be represented as the constant cross-sectional profile of the first light coupler 220 projected along the linear axis. Alternatively, in some embodiments, the axis may be non-linear, and the first light coupler 220 may be represented as the constant cross- sectional profile of the first light coupler 220 projected along the non-linear axis.

[0048] In some embodiments, the first edge 303a, 303b, 303c of each waveguide 300a, 300b, 300c of the plurality of concentric waveguides may face the outer edge 213 of the light guide plate 210. Additionally, in some embodiments, the light source 225 may face the second edge 304a, 304b, 304c of each waveguide 300a, 300b, 300c of the plurality of concentric waveguides. The light source 225 may be oriented to provide light from the light source 225 to the second edge 304a, 304b, 304c. For example, in some embodiments, the light source 225 may provide light from a light emitting region 224 of the light source 225. In some embodiments, the light source 225 may include one or more light emitting diodes (LEDs), light bars, light rods, light arrays, one or more light bulbs, and/or one or more optical fibers defining at least a portion of the light emitting region 224. In some embodiments, each of the plurality of concentric waveguides 300a, 300b, 300c may, therefore, guide optical waves (e.g., light from the light emitting region 224 of the light source 225) from the second edge 304a, 304b, 304c through each waveguide 300a, 300b, 300c along the arcuate path 305a, 305b, 305c to the first edge 303a, 303b, 303c and into the outer edge 213 of the light guide plate 210 based at least in part on total internal reflection of the optical waves within each waveguide 300a, 300b, 300c.

[0049] In some embodiments, the first edge 303a, 303b, 303c of each waveguide 300a, 300b, 300c of the plurality of concentric waveguides may be coupled to the outer edge 213 of the light guide plate 210. For example, in some embodiments, the first edge 303a, 303b, 303c of each waveguide 300a, 300b, 300c may be at least one of optically and mechanically coupled to the outer edge 213 of the light guide plate 210. Similarly, in some embodiments, the second edge 304a, 304b, 304c of each waveguide 300a, 300b, 300c of the plurality of concentric waveguides may be coupled to the light emitting region 224 of the light source 225. For example, in some embodiments, the second edge 304a, 304b, 304c of each waveguide 300a, 300b, 300c may be at least one of optically and mechanically coupled to the light emitting region 224 of the light source 225. In some embodiments, the first edge 303a, 303b, 303c may be optically coupled to the outer edge 213 by being positioned in physical contact with (e.g., abutting) the outer edge 213. Similarly, in some embodiments, the second edge 304a, 304b, 304c may be optically coupled to the light emitting region 224 of the light source 225 by being positioned in physical contact with (e.g., abutting) the light emitting region 224.

[0050] Alternatively, in some embodiments, the first edge 303a, 303b, 303c may be spaced a distance from the outer edge 213 and/or the second edge 304a, 304b, 304c may be spaced a distance from the light emitting region 224. Additionally, in some embodiments, an optical medium (e.g., transparent adhesive, optical filter, optical coupler, etc.) may be positioned between at least one of the light emitting region 224 and the second edge 304a, 304b, 304c and the outer edge 213 and the first edge 303a, 303b, 303c to optically couple the light emitting region 224 to the second edge 304a, 304b, 304c and the outer edge 213 to the first edge 303a, 303b, 303c. For example, in some embodiments, the back light unit 200 may include an optically transparent adhesive (not shown) that optically and mechanically couples the first edge 303a, 303b, 303c to the outer edge 213 and that optically and mechanically couples the second edge 304a, 304b, 304c to the light emitting region 224. In some embodiments, the optically transparent adhesive may include a refractive index that matches the refractive index of at least one of the waveguides 300a, 300b, 300c and the light guide plate 210. In some embodiments, by providing an optically transparent adhesive including a matching refractive index, the waveguides 300a, 300b, 300c may be optically coupled to at least one of the light emitting region 224 of the light source 225 and the outer edge 213 of the light guide plate 210, thereby reducing or eliminating reflections of optical waves (e.g., light) in to and out of the waveguides 300a, 300b, 300c, the outer edge 213 of the light guide plate 210, and the light emitting region 224 of the light source 225. For purposes of this disclosure, unless otherwise noted, "light" is considered to be visible light with wavelengths from 400 nanometers to 700 nanometers. Likewise, an element (e.g., adhesive) is considered "transparent" if greater than or equal to 85% of visible light may pass through the element.

[0051] Optically coupling the light emitting region 224 of the light source 225 to the second edge 304a, 304b, 304c of the waveguides 300a, 300b, 300c and optically coupling the outer edge 213 of the light guide plate 210 to the first edge 303a, 303b, 303c of the waveguides 300a, 300b, 300c may illuminate the waveguides 300a, 300b, 300c based on the coupled light from the light source 225 provided to the second edge 304a, 304b, 304c and may also illuminate the light guide plate 210 based on the coupled light from the waveguides 300a, 300b, 300c. In some embodiments, illuminating an object (e.g., the waveguides 300a, 300b, 300c, and the light guide plate 210) based on light provided (e.g., from the light source 225) to an edge of the object (e.g., the first edge 303a, 303b, 303c and the second edge 304a, 304b, 304c of the waveguides 300a, 300b, 300c, and the outer edge 213 of the light guide plate 210) may be known as "edge-lighting." For example, in some embodiments, based on "edge-lighting," light provided from the light emitting region 224 of the light source 125 may propagate through the first light coupler 220 and into the light guide plate 210 in a direction away from the outer edge 213 to travel through the light guide plate 210 between the first major surface 211 and the second major surface 212 thereby illuminated the light guide plate 210.

[0052] In some embodiments, "edge- lighting" of the light guide plate 210 may provide a back light unit 200 having smaller dimensions (e.g., a thinner profile) and a back light unit 200 of less weight than, for example, a back light unit that is illuminated with light sources positioned behind the unit (not shown) oriented to direct light onto the second major surface 212 of the light guide plate 210, known as "back-lighting". For example, light sources positioned behind (e.g., facing the second major surface 212 of the light guide plate 210) may illuminate the back light unit 200. However, in some embodiments, lighting the back light unit 200 with light sources facing the second major surface 212 of the light guide plate 210 may require more light sources to provide a same or similar illumination of the back light unit 200 as compared to the number of light sources provided when the back light unit 200 is illuminated by "edge-lighting" of the light guide plate 210. Similarly, in some embodiments, lighting the back light unit 200 with light sources facing the second major surface 212 of the light guide plate 210 may provide a comparatively thicker back light unit 200 relative to a thickness of a back light unit 200 illuminated by "edge-lighting" of the light guide plate 210. Accordingly, in some embodiments, as trends toward smaller, lighter, and thinner electronic displays 100 may be pursued, the "edge-lit" back light unit 200 of the present disclosure may provide several advantages over back light units illuminated, for example, by light sources positioned behind the light guide plate 210 and facing the second major surface 212 of the light guide plate 210 including reducing the housing dimension "D" shown in FIG. 2.

[0053] Moreover, in some embodiments, "edge-lighting" of the light guide plate 210 with a first light coupler 220 including a bent or curved profile (e.g., defined by the arcuate paths 305a, 305b, 305c) may provide a back light unit 200 having smaller dimensions (e.g., a narrower bezel 115, shown in FIG. 1 and FIG. 2) and a back light unit 200 of less weight than, for example, a back light unit that is illuminated with light sources positioned laterally adjacent to the unit (not shown) and oriented to direct light from the light source along a linear path into the outer edge 213 of the light guide plate 210. For example, light sources positioned laterally adjacent to (e.g., facing the outer edge 213 of the light guide plate 210) and outside of the outer edge 213 of the light guide plate 210 may illuminate the back light unit 200. However, in some embodiments, lighting the back light unit 200 with light sources facing the outer edge 213 of the light guide plate 210 may require a larger housing 105 including a wider bezel 115 to accommodate the light sources. Therefore, in some embodiments, by positioning the light source 225 in accordance with embodiments of the disclosure internal to the outer edge 213 of the light guide plate 210 (e.g., beneath the light guide plate 210 and within the housing 105) and directing light along the arcuate paths 305a, 305b, 305c with the first light coupler 220 including a bent or curved profile, the width "W" of the bezel 115 may be reduced or eliminated and the light guide plate 210 may be illuminated based at least in part on "edge-lighting" of the light guide plate 210.

[0054] Thus, in some embodiments, as compared to illumination achieved by "back-lighting" with light sources facing the second major surface 212 of the light guide plate 210 and/or "edge-lighting" with light sources positioned laterally adjacent to and outside of the outer edge 213 of the light guide plate 210, features of the present disclosure that include a first light coupler 220 including a bent or curved profile (e.g., defined by the arcuate paths 305a, 305b, 305c) may provide a back light unit 200 and an electronic display 100 that may be one or more of smaller, lighter, narrower, and thinner, than other back light units and electronic displays. Accordingly, in some embodiments, as trends toward smaller, lighter, narrower, and thinner electronic displays 100 may be pursued, the "edge-lit" back light unit 200 including a bent or curved profile (e.g., defined by the arcuate paths 305a, 305b, 305c) of the present disclosure may provide several advantages over other back light units including reducing the housing dimension "D" shown in FIG. 2, and reducing or eliminating the bezel width "W", shown in FIG. 1 and FIG. 2. [0055] Additionally, in some embodiments, the first light coupler 220 may include a gap 307, 308 between a respective one of the inner surface 301b, 301c and a respective one of the outer surface 302a, 302b of adjacent waveguides (e.g., adjacent waveguides 300a, 300b, and adjacent waveguides 300b, 300c). In some embodiments, the gap 307, 308 may extend along the entire arcuate path (e.g., one or more of arcuate path 305a, 305b, 305c) between the respective one of the inner surface 301b, 301c and the respective one of the outer surface 302a, 302b of adjacent waveguides. In some embodiments, providing the gap 307, 308 along the entire arcuate path 305a, 305b, 305c as compared to, for example, providing the gap 307, 308 along only a portion of the arcuate path 305a, 305b, 305c may enable employment of an increased number of waveguides 300a, 300b, 300c and may enable a tighter (e.g., smaller) bend radius Ra, Rb, Rc.

[0056] In some embodiments, the gap 307, 308 may include at least one of air and a material having a refractive index about 0.2 less than a refractive index of a material of the adjacent waveguides (e.g., adjacent waveguides 300a, 300b, and adjacent waveguides 300b, 300c). Additionally, in some embodiments, the at least one of air and a material having a refractive index about 0.2 less than a refractive index of a material of the adjacent waveguides may be provided at the inner surface 301a of the waveguide 300a and the outer surface 302c of the waveguide 300c. For example, in some embodiments, the waveguides 300a, 300b, 300c may be manufactured from one or more of glass (e.g., aluminosilicate, alkali-aluminosilicate, borosilicate, alkali-borosilicate, aluminoborosilicate, alkali-aluminoborosilicate, chemically strengthened glass, thermally tempered glass, etc.), polymer (e.g., polymethyl methacrylate), or other material oriented to guide optical waves (e.g., light) based at least in part on total internal reflection of the optical waves within each waveguide 300a, 300b, 300c. By providing the at least one of air and a material having a refractive index about 0.2 less than a refractive index of a material of the adjacent waveguides, optical waves within the waveguide 300a, 300b, 300c are more likely to remain within the waveguide 300a, 300b, 300c and are less likely to diffuse out of the waveguide 300a, 300b, 300c than, for example, if the gap 307, 308 included a material having a refractive index about 0.2 greater than a refractive index of a material of the adjacent waveguides. Thus, in some embodiments, based at least in part on total internal reflection of optical waves within each waveguide 300a, 300b, 300c, features of the disclosure may include improved optical transmission properties of the waveguides 300a, 300b, 300c that provide a more efficient back light unit 200 and/or an optically brighter (e.g., illuminated) display panel 110.

[0057] Additionally, as shown in FIG. 4, which shows a cross-sectional view of the first light coupler 220 along line 4-4 taken perpendicular to the arcuate path 305a, 305b, 305c of FIG. 3, in some embodiments, each waveguide 300a, 300b, 300c of the plurality of concentric waveguides may include a rectangular cross-sectional profile. Likewise, in some embodiments, the rectangular cross -sectional profile of each waveguide 300a, 300b, 300c may be constant along the entire arcuate path 305a, 305b, 305c. For example, in some embodiments, the rectangular profile may be projected along the arcuate path 305a, 305b, 305c, and a view of the waveguides 300a, 300b, 300c taken perpendicular to the arcuate path 305a, 305b, 305c at any location over the central angle 310 of FIG. 3, may have the same (e.g., identical) features as the features of the rectangular (e.g., slab) waveguides 300a, 300b, 300c shown in FIG. 4. In some embodiments, one or more waveguides 300a, 300b, 300c of the plurality of concentric waveguides may include a polygonal profile and/or a profile that varies at one or more locations along the arcuate path 305a, 305b, 305c without departing from the scope of the disclosure. Additionally, the waveguides 300a, 300b, 300c may include a length "L" along which the waveguides 300a, 300b, 300c extend. In some embodiments, the length "L" of the waveguides 300a, 300b, 300c may correspond to, for example, a length or width of the outer edge 213 of the light guide plate 210. For example, in some embodiments, the length "L" of the waveguides 300a, 300b, 300c may be selected such that the first edge 303a, 303b, 303c of the waveguides 300a, 300b, 300c may be at least one of optically and mechanically coupled to the outer edge 213 of the light guide plate 210 along a corresponding length or width (e.g., an entire length or width) of the light guide plate 210 [0058] Additionally, in some embodiments, the gap 307, 308 may define a distance dl, d2 between the respective one of the inner surface 301b, 301c and the respective one of the outer surface 302a, 302b of adjacent waveguides 300a, 300b and 300b, 300c. That is, in some embodiments, the gap 307 may define the distance dl between the inner surface 301b of waveguide 300b and the outer surface 302a of waveguide 300a. Likewise, in some embodiments, the gap 308 may define the distance d2 between the inner surface 301c of waveguide 300c and the outer surface 302b of waveguide 300b. In some embodiments, the waveguides 300a, 300b, 300c may be positioned relative to each other supported by a frame (not shown) or an adhesive (not shown). In some embodiments, the distance dl, d2 may be from about 1 micron to about 10 microns; however, in some embodiments, the distance dl, d2 may be less than about 1 micron or greater than about 10 microns without departing from the scope of the disclosure. In some embodiments, the distance dl, d2 may be constant. For example, in some embodiments, the distance dl, d2 may be constant over the entire central angle 310 relative to the radius Ra, Rb, Rc. Alternatively, in some embodiments, the distance, dl, d2 may vary over the central angle 310 relative to the radius Ra, Rb, Rc and may, therefore, include relatively smaller and larger distances at one or more locations defining the gap 307, 308.

[0059] Providing the first light coupler 220 with a plurality of concentric waveguides 300a, 300b, 300c may provide several mechanical advantages. For example, in some embodiments, compared to a relatively thicker single waveguide, a plurality of relatively thinner concentric waveguides (an effective thickness of which may equal the thickness of the relatively thicker single waveguide) may include comparatively smaller induced stresses based at least in part on the bent or curved profile of the waveguide for equivalent bend radii. Considering a relatively thicker single waveguide including a predetermined bend radius, a compressive stress at the inner surface of the waveguide and a tensile stress at the outer surface of the waveguide may be induced based at least in part on the flexural rigidity of the waveguide and the bending forces (e.g., moments) applied to bend the waveguide to assume the desired bent or curved profile. For the predetermined bend radius, the tensile stress at the outer surface of the relatively thicker single waveguide may, therefore, be greater than a comparable tensile stress at the outer surface of a relatively thinner waveguide having the same bend radius. Thus, in some embodiments, the relatively thinner waveguide may be bent to include a comparatively smaller radius while inducing the equivalent tensile stress at the outer surface of the waveguide induced in the relatively thicker single waveguide. Therefore, providing the first light coupler 220 with a plurality of concentric waveguides 300a, 300b, 300c may enable employment of waveguides 300a, 300b, 300c including tighter (e.g., smaller) radii Ra, Rb, Rc. In some embodiments, the waveguides 300a, 300b, 300c of the disclosure may, therefore, provide a reduced or eliminated bezel width "W" as compared to a corresponding bezel width accommodating a single bent waveguide. Similarly, in some embodiments, the waveguides 300a, 300b, 300c of the disclosure may, therefore, provide a reduced housing dimension "D" as compared to a corresponding housing dimension accommodating a single bent waveguide.

[0060] Moreover, in some embodiments, providing the first light coupler 220 with a plurality of concentric waveguides 300a, 300b, 300c may provide several optical advantages. In some embodiments, while typical convention may suggest that more light may propagate through a comparatively larger waveguide than an amount of light propagating through a comparatively smaller waveguide, this convention may not apply when the waveguide includes a bent or curved profile. For example, in some embodiments, compared to a relatively thicker single waveguide, a plurality of relatively thinner concentric waveguides (an effective thickness of which may equal the thickness of the relatively thicker single waveguide) may propagate (e.g., guide light within the waveguide based on total internal reflection) comparatively more efficiently (e.g., with less diffusion or loss) within the bent or curved profile of the waveguide for equivalent bend radii. Considering a relatively thicker single waveguide including a predetermined bend radius, an amount of light from the light emitting region 224 of the light source 225 may be provided to and guided within the waveguide. Because the thickness of the relatively thicker waveguide is greater than the respective thickness of each relatively thinner waveguide of the plurality of concentric waveguides 300a, 300b, 300c the light may be less confined within the relatively thicker single waveguide and more confined within each of the relatively thinner waveguides 300a, 300b, 300c. By confining the light more efficiently within the plurality of relatively thinner waveguides 300a, 300b, 300c may provide, the loss of light (e.g., diffusion of light out of the waveguides 300a, 300b, 300c) may be less when coupling light with the plurality of relatively thinner concentric waveguides 300a, 300b, 300c than the loss of light when coupling light with the relatively thicker single waveguide. Thus, in some embodiments, increased optical coupling and guiding efficiency may be obtained by providing a first light coupler 220 including a bent or curved profile (e.g., defined by the arcuate path 305a, 305b, 305c) with a plurality of concentric waveguides 300a, 300b, 300c as compared to a single waveguide including a comparable bent or curved profile.

[0061] Therefore, providing the first light coupler 220 with a plurality of concentric waveguides 300a, 300b, 300c may enable employment of waveguides 300a, 300b, 300c including tighter (e.g., smaller) radii Ra, Rb, Rc than the radius of the single waveguide while providing he same, similar, or better optical illumination of the light guide plate 210 as that provided by a single waveguide. Alternatively or in addition, providing the first light coupler 220 with a plurality of concentric waveguides 300a, 300b, 300c that include increased optical coupling and guiding efficiency as compared to a single waveguide may provide a comparatively brighter display panel 110, and may permit employment of fewer light sources, thereby reducing cost, weight, and heat production of the back light unit 200. In some embodiments, based at least on the increased optical coupling and guiding efficiency, the size of the waveguides 300a, 300b, 300c of the disclosure may be reduced relative to the size of a single relatively thicker waveguide while still providing the same, similar, or better illumination characteristics as the single relatively thicker waveguide. Therefore, in some embodiments, the first light coupler 220 including a plurality of concentric waveguides 300a, 300b, 300c may provide a reduced or eliminated bezel width "W" as compared to a corresponding bezel width accommodating a single bent waveguide. Similarly, in some embodiments, the plurality of concentric waveguides 300a, 300b, 300c of the disclosure may, therefore, provide a reduced housing dimension "D" as compared to a corresponding housing dimension accommodating a single bent waveguide.

[0062] As shown in FIG. 4, in some embodiments, a thickness "ta", "tb", "tc" of each waveguide 300a, 300b, 300c defined between the inner surface 301a, 301b, 301c and the outer surface 302a, 302b, 302c may be from about 0.2 mm to about 2.0 mm. In some embodiments, the radius (e.g., Ra) of an innermost waveguide (e.g., waveguide 300a) of the plurality of concentric waveguides may be from about 1 mm to about 10 mm. In some embodiments, the radius Ra of the innermost waveguide 300a may be about 1 mm. Additionally, in some embodiments, a thickness "T" of the first light coupler 220 may be defined between the inner surface 301a of an innermost waveguide 300a of the plurality of concentric waveguides and the outer surface 302c of an outermost waveguide 300c of the plurality of concentric waveguides. Turning back to FIG. 3, in some embodiments, a thickness "t" of the light guide plate 210 may be defined between the first major surface 211 of the light guide plate 210 and the second major surface 212 of the light guide plate 210. In some embodiments, the thickness "t" may be from about 1 mm to about 4 mm; however, in some embodiments, the thickness "t" may be less than about 1 mm or greater than about 4 mm without departing from the scope of the disclosure. Moreover, in some embodiments, the light emitting region 224 of the light source 225 may include a height "hi". In some embodiments, the thickness "t" of the light guide plate 210 may be equal to the thickness "T" of the first light coupler 220, and in some embodiments, the thickness "T" of the first light coupler 220 may be equal to the height "hi" of the light emitting region 224 of the light source 225.

[0063] As shown in FIG. 5, in some embodiments, the back light unit 200 may include a second light coupler 520 including a first surface 521 coupled to the second edge 304a, 304b, 304c of each waveguide 300a, 300b, 300c of the plurality of concentric waveguides and a second surface 522 coupled to a light source 525. In some embodiments, the first surface 521 may be at least one of optically and mechanically coupled to the second edge 304a, 304b, 304c. In some embodiments the light source 525 may be oriented to provide light from the light source 525 to the second surface 522. For example, in some embodiments, the second surface 522 may be at least one of optically and mechanically coupled to a light emitting region 524 of the light source 525. In some embodiments, a height "h2" of the light emitting region 524 of the light source 525 may be greater than the thickness "t" of the light guide plate 210 defined between the first major surface 211 of the light guide plate 210 and the second major surface 212 of the light guide plate 210. In some embodiments, the height "h2" of the light emitting region 524 may correspond to a dimension of the second surface 522 of the second light coupler 520. In some embodiments, the thickness "T" of the first light coupler 220 defined between the inner surface 301a of an innermost waveguide 300a of the plurality of concentric waveguides and the outer surface 302c of an outermost waveguide 300c of the plurality of concentric waveguides may be less than the height "h2" of the light emitting region 524 of the light source 525. In some embodiments, the thickness "T" of the first light coupler 220 may correspond to a dimension of the first surface 521 of the second light coupler 520 Additionally, in some embodiments, the thickness "T" of the first light coupler 220 may be approximately equal to the thickness "t" of the light guide plate 210.

[0064] Thus, in some embodiments, compared to the light source 225 in FIG. 3, for example, a relatively larger light source 525 including a relatively larger light emitting region 524 may be employed and may, therefore, provide light from the light emitting region 524 through the second light coupler 520, through the first light coupler 220, and to the light guide plate 210. In some embodiments, the relatively larger light source 525 including the relatively larger light emitting region 524 including a height "h2" may provide (e.g., emit) at least one of more light and brighter light than, for example, a relatively smaller light source (e.g., light source 225) including a relatively smaller light emitting region (e.g., light emitting region 224) including a height "hi" that may be less than height "h2". Thus, in some embodiments, providing the back light unit 200 with a second light coupler 520 in accordance with embodiments of the disclosure may provide a relatively brighter and more efficiently illuminated back light unit 200.

[0065] Similarly, as shown in FIG. 6, the back light unit 200 may include a second light coupler 620. For example, FIG. 7, shows a view of the second light coupler 620 along line 7-7 of FIG. 6. In some embodiments, the second light coupler 620 may include a first surface 621a, 621b, 621c (See FIG. 7) coupled to the second edge 304a, 304b, 304c of each waveguide 300a, 300b, 300c of the plurality of concentric waveguides and a second surface 622a, 622b, 622c (See FIG. 6) coupled to a light source 625. In some embodiments, the first surface 621a, 621b, 621c may be at least one of optically and mechanically coupled to the second edge 304a, 304b, 304c. In some embodiments, the light source 625 may be oriented to provide light from the light source 625 to the second surface 622a, 622b, 622c. For example, in some embodiments, the second surface 622a, 622b, 622c may be at least one of optically and mechanically coupled to a light emitting region 624 of the light source 625. In some embodiments, a height "h3" of the light emitting region 624 of the light source 625 may be greater than the thickness "t" of the light guide plate 210 defined between the first major surface 211 of the light guide plate 210 and the second major surface 212 of the light guide plate 210. In some embodiments, the height "h3" of the light emitting region 624 may correspond to a dimension of the second surface 622a, 622b, 622c of the second light coupler 620. In some embodiments, the thickness "T" of the first light coupler 220 defined between the inner surface 301a of an innermost waveguide 300a of the plurality of concentric waveguides and the outer surface 302c of an outermost waveguide 300c of the plurality of concentric waveguides may be less than the height "h3" of the light emitting region 624 of the light source 625. In some embodiments, the thickness "T" of the first light coupler 220 may correspond to a dimension of the first surface 621a, 621b, 621c of the second light coupler 620. Additionally, in some embodiments, the thickness "T" of the first light coupler 220 may be approximately equal to the thickness "t" of the light guide plate 210.

[0066] Thus, in some embodiments, compared to the light source 225 in FIG. 3, for example, a relatively larger light source 625 including a relatively larger light emitting region 624 may be employed and may, therefore, provide light from the light emitting region 624 through the second light coupler 620, through the first light coupler 220, and to the light guide plate 210. In some embodiments, the relatively larger light source 625 including the relatively larger light emitting region 624 including a height "h3" may provide (e.g., emit) at least one of more light and brighter light than, for example, a relatively smaller light source (e.g., light source 225) including a relatively smaller light emitting region (e.g., light emitting region 224) including a height "hi" that may be less than height "h3". Thus, in some embodiments, providing the back light unit 200 with a second light coupler 620 in accordance with embodiments of the disclosure may provide a relatively brighter and more efficiently illuminated back light unit 200.

[0067] FIG. 8 illustrates an exemplary plot for waveguides (e.g., one or more of waveguides 300a, 300b, 300c) including different thicknesses 801, 802, 803. The plot was generated using computer modeling and analysis techniques in accordance with embodiments of the disclosure for an exemplary waveguide 801 including a thickness of 0.2 mm, an exemplary waveguide 802 including a thickness of 0.7 mm, and an exemplary waveguide 803 including a thickness of 2.0 mm. The vertical or "Y" axis represents optical loss in decibels (dB) and the horizontal or "X" axis represents radius (e.g., Ra, Rb, Rc) of the waveguide in millimeters (mm). Therefore, line 811 represents the relationship between optical loss and waveguide radius for the waveguide 801, line 812 represents the relationship between optical loss and waveguide radius for the waveguide 802, and line 813 represents the relationship between optical loss and waveguide radius for the waveguide 803. In some embodiments, optical loss may be defined as a measured, perceived, or calculated difference (e.g., ratio) between a reference power and an actual power. For example, referring to FIG. 3, the light emitting region 224 of the light source 225 may provide light including a reference power (e.g., lumens) to the second edge 304a, 304b, 304c of the waveguide 300a, 300b, 300c. The light may propagate through the waveguides 300a, 300b, 300c and exit the first edge 303a, 303b, 303c of the waveguide 300a, 300b, 300c optically coupled to the outer edge 213 of the light guide plate 210 at an actual power. The measured, perceived, or calculated difference between the reference power and the actual power may, therefore, define the optical loss. For example, an optical loss of zero, therefore, corresponds to no difference between the reference power and the actual power, and optical loss values greater than zero correspond to a reduction in the actual power relative to the reference power. The closer the optical loss is to zero, the more efficient the waveguide 300a, 300b, 300c is at guiding light.

[0068] Accordingly, as shown in FIG. 8, based on the computer modeling and analysis techniques, as shown by line 811, for waveguide 801 (including a thickness of 0.2 mm) an optical loss approaching zero may be obtained at a bend radius of about 1 mm. Likewise, as shown by line 812, for waveguide 802 (including a thickness of 0.7 mm) an optical loss approaching zero may be obtained at a bend radius of about 3.5 mm. Additionally, as shown by line 813, for waveguide 803 (including a thickness of 2.0 mm) an optical loss approaching zero may be obtained at a bend radius of about 10 mm. Thus, based on the plot of FIG. 8, depending on, for example, an acceptable or desired optical loss and a desired thickness "T" of the first light coupler 220, the thickness, bend radius, and number of waveguides to obtain a plurality of waveguides achieving desired optical characteristics may be selected.

[0069] FIG. 9 illustrates an exemplary plot for waveguides (e.g., one or more of waveguides 300a, 300b, 300c) including different thicknesses 901, 902, 903. The plot was generated using computer modeling and analysis techniques in accordance with embodiments of the disclosure for an exemplary waveguide 901 including a thickness of 0.2 mm, an exemplary waveguide 902 including a thickness of 0.7 mm, and an exemplary waveguide 903 including a thickness of 2.0 mm. The vertical or "Y" axis represents optical transmission in percent (%) and the horizontal or "X" axis represents radius (e.g. , Ra, Rb, Rc) of the waveguide in millimeters (mm). Therefore, line 911 represents the relationship between optical transmission and waveguide radius for the waveguide 901, line 912 represents the relationship between optical transmission and waveguide radius for the waveguide 902, and line 913 represents the relationship between optical transmission and waveguide radius for the waveguide 903. In some embodiments, optical transmission percentage may be defined as a percentage of measured, perceived, or calculated actual power relative to a reference power. For example, referring to FIG. 3, the light emitting region 224 of the light source 225 may provide light including a reference power (e.g., lumens) to the second edge 304a, 304b, 304c of the waveguide 300a, 300b, 300c. The light may propagate through the waveguides 300a, 300b, 300c and exit the first edge 303a, 303b, 303c of the waveguide 300a, 300b, 300c optically coupled to the outer edge 213 of the light guide plate 210 at an actual power. The percentage of the measured, perceived, or calculated actual power relative to the reference power may, therefore, define the optical transmission percentage. For example, an optical transmission percentage of 100, therefore, corresponds to no difference between the reference power and the actual power, and optical transmission percentage values less than 100 correspond to a reduction in the actual power relative to the reference power. The closer the optical transmission percentage is to 100, the more efficient the waveguide 300a, 300b, 300c is at guiding light.

[0070] Accordingly, as shown in FIG. 9, based on the computer modeling and analysis techniques, as shown by line 911, for waveguide 902 (including a thickness of 0.2 mm) an optical transmission percentage approaching 100 percent may be obtained at a bend radius of about 1 mm. Likewise, as shown by line 912, for waveguide 902 (including a thickness of 0.7 mm) an optical transmission percentage approaching 100 percent may be obtained at a bend radius of about 3.5 mm. Additionally, as shown by line 913, for waveguide 903 (including a thickness of 2.0 mm) an optical transmission percentage approaching 100 percent may be obtained at a bend radius of about 10 mm Thus, based on the plot of FIG. 9, depending on, for example, an acceptable or desired optical transmission percentage and a desired thickness "T" of the first light coupler 220, the thickness, bend radius, and number of waveguides to obtain a plurality of waveguides achieving desired optical characteristics may be selected.

[0071] It will be appreciated that the various disclosed embodiments may involve particular features, elements or steps that are described in connection with that particular embodiment. It will also be appreciated that a particular feature, element or step, although described in relation to one particular embodiment, may be interchanged or combined with alternate embodiments in various non-illustrated combinations or permutations.

[0072] It is to be understood that, as used herein the terms "the," "a," or "an," mean "at least one," and should not be limited to "only one" unless explicitly indicated to the contrary. Thus, for example, reference to "a component" includes embodiments having two or more such components unless the context clearly indicates otherwise.

[0073] Ranges may be expressed herein as from "about" one particular value, and/or to "about" another particular value. When such a range is expressed, embodiments include from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

[0074] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that any particular order be inferred.

[0075] While various features, elements or steps of particular embodiments may be disclosed using the transitional phrase "comprising," it is to be understood that alternative embodiments, including those that may be described using the transitional phrases "consisting" or "consisting essentially of," are implied. Thus, for example, implied alternative embodiments to an apparatus that comprises A+B+C include embodiments where an apparatus consists of A+B+C and embodiments where an apparatus consists essentially of A+B+C. [0076] It will be apparent to those skilled in the art that various modifications and variations may be made to the present disclosure without departing from the spirit and scope of the disclosure. Thus, it is intended that the present disclosure cover the modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalents.

Claims

CLAIMS What is claimed is:

1. A back light unit comprising:

a light guide plate;

a light coupler comprising a plurality of concentric waveguides, each of the plurality of concentric waveguides comprising an inner surface and an outer surface extending from a first edge of the waveguide to a second edge of the waveguide along an arcuate path defining a radius of the waveguide, the first edge of each of the plurality of concentric waveguides facing an outer edge of the light guide plate; and a light source facing the second edge of each of the plurality of concentric waveguides.

2. The back light unit of claim 1 , wherein the inner surface and the outer surface of each of the plurality of concentric waveguides extend equidistant from each other along the arcuate path without diverging or converging.

3. The back light unit of claim 1 or claim 2, wherein the radius of each of the plurality of concentric waveguides is constant.

4. The back light unit of any one of claims 1 -3, wherein the light coupler further comprises a gap defining a distance between adjacent waveguides.

5. The back light unit of claim 4, wherein the gap comprises at least one of air and a material having a refractive index about 0.2 less than a refractive index of a material of the adjacent waveguides.

6. The back light unit of claim 4 or claim 5, wherein the gap extends along the entire arcuate path between adjacent waveguides.

7. The back light unit of any of claims 4-6, wherein the distance is from about 1 micron to about 10 microns.

8. The back light unit of any one of claims 4-7, wherein the distance is constant.

9. The back light unit of any one of claims 1-8, wherein each of the plurality of concentric waveguides comprises a rectangular cross-sectional profile taken perpendicular to the arcuate path.

10. The back light unit of claim 9, wherein the rectangular cross-sectional profile is constant along the entire arcuate path.

11. The back light unit of any one of claims 1-10, wherein a central angle defining an arc length between the first edge and the second edge of each of the plurality of concentric waveguides is from about 90° to about 180°.

12. The back light unit of claim 11, wherein the central angle is about 180°.

13. The back light unit of any one of claims 1-12, wherein a thickness of each of the plurality of concentric waveguides defined between the inner surface and the outer surface is from about 0.2 mm to about 2.0 mm.

14. The back light unit of any one of claims 1-12, wherein the radius of an innermost waveguide of the plurality of concentric waveguides is from about 1 mm to about 10 mm.

15. The back light unit of claim 14, wherein the radius of the innermost waveguide is about 1 mm.

16. An electronic display comprising the back light unit of any one of claims 1-15, wherein the back light unit is oriented to face a major surface of a display panel.

17. A back light unit comprising:

a light guide plate comprising a first major surface and a second major surface;

a first light coupler comprising a plurality of concentric waveguides, each of the plurality of concentric waveguides comprising an inner surface and an outer surface extending from a first edge of the waveguide to a second edge of the waveguide along an arcuate path defining a radius of the waveguide, the first edge of each of the plurality of concentric waveguides facing an outer edge of the light guide plate; and

a second light coupler comprising a first surface coupled to the second edge of each of the plurality of concentric waveguides and a second surface coupled to a light source, wherein a height of a light emitting region of the light source is greater than a thickness of the light guide plate defined between the first major surface of the light guide plate and the second major surface of the light guide plate.

18. The back light unit of claim 17, wherein the inner surface and the outer surface of each of the plurality of concentric waveguides extend equidistant from each other along the arcuate path without diverging or converging.

19. The back light unit of claim 17 or claim 18, wherein a thickness of the first light coupler defined between the inner surface of an innermost waveguide of the plurality of concentric waveguides and the outer surface of an outermost waveguide of the plurality of concentric waveguides is less than the height of the light emitting region of the light source.

20. The back light unit of claim 19, wherein the thickness of the first light coupler is approximately equal to the thickness of the light guide plate.

21. An electronic display comprising the back light unit of any one of claims 17-20, wherein the back light unit is oriented to face a major surface of a display panel.

22. A light coupler comprising:

a plurality of concentric waveguides, each of the plurality of concentric waveguides comprising an inner surface and an outer surface extending from a first edge of the waveguide to a second edge of the waveguide along an arcuate path defining a radius of the waveguide.

23. The light coupler of claim 22, wherein the inner surface and the outer surface of each of the plurality of concentric waveguides extend equidistant from each other along the arcuate path without diverging or converging.

24. The light coupler of claim 22 or claim 23, wherein the radius of each of the plurality of concentric waveguides is constant.

25. The light coupler of any one of claims 22-24, wherein the light coupler further comprises a gap defining a distance between adjacent waveguides.

26. The light coupler of claim 25, wherein the gap comprises at least one of air and a material having a refractive index about 0.2 less than a refractive index of a material of the adjacent waveguides.

27. The light coupler of claim 25 or claim 26, wherein the gap extends along the entire arcuate path between adjacent waveguides.

28. The light coupler of any of claims 25-27, wherein the distance is from about 1 micron to about 10 microns.

29. The light coupler of any one of claims 25-28, wherein the distance is constant.

30. The light coupler of any one of claims 22-29, wherein each of the plurality of concentric waveguides comprises a rectangular cross-sectional profile taken perpendicular to the arcuate path.

31. The light coupler of claim 30, wherein the rectangular cross-sectional profile is constant along the entire arcuate path.

32. The light coupler of any one of claims 22-31, wherein a central angle defining an arc length between the first edge and the second edge of each of the plurality of concentric waveguides is from about 90° to about 180°.

33. The light coupler of claim 32, wherein the central angle is about 180°.

34. The light coupler of any one of claims 22-33, wherein a thickness of each of the plurality of concentric waveguides defined between the inner surface and the outer surface is from about 0.2 mm to about 2.0 mm.

35. The light coupler of any one of claims 22-34, wherein the radius of an innermost waveguide of the plurality of concentric waveguides is from about 1 mm to about 10 mm.

36. The light coupler of claim 35, wherein the radius of the innermost waveguide is about 1 mm.

37. A back light unit comprising the light coupler of any one of claims 22-36, wherein the first edge of each of the plurality of concentric waveguides faces an outer edge of a light guide plate.

38. An electronic display comprising the back light unit of claim 37, wherein the back light unit is oriented to face a major surface of a display panel.