Patent Publication Number: US-2016245986-A1

Title: Light guide assembly, housing assembly, and lighting assembly including same

Description:
RELATED APPLICATION DATA 
     This application claims the benefit of U.S. Provisional Patent Application No. 62/120,517, filed Feb. 25, 2015; and claims the benefit of U.S. Provisional Patent Application No. 62/180,137, filed Jun. 16, 2015; the disclosures of which are incorporated herein by reference in their entireties. 
    
    
     BACKGROUND 
     Energy efficiency has become an area of interest for energy consuming devices. One class of energy consuming devices is lighting devices. Light emitting diodes (LEDs) show promise as energy efficient light sources for lighting devices, and may be used together with light guides as LED lighting assemblies. But there are issues associated with producing these LED lighting assemblies in various shapes and sizes, for example, in terms of cost, reproducibility, and/or light output distribution. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic perspective view of an exemplary light guide assembly. 
         FIG. 2  is a schematic perspective view of an exemplary light guide segment. 
         FIGS. 3-5  are schematic side views of parts of an exemplary light guide assembly. 
         FIGS. 6-8  are schematic side views of parts of an exemplary light guide assembly. 
         FIGS. 9A-9G  are schematic side views of parts of exemplary light guide assemblies. 
         FIGS. 10-12  are schematic top views of parts of exemplary lighting assemblies. 
         FIG. 13  is a schematic perspective view of parts of an exemplary lighting assembly. 
         FIG. 14  is a schematic perspective view of an exemplary lighting assembly segment. 
         FIG. 15  is a schematic view of an exemplary housing segment. 
         FIG. 16  is a schematic view of an exemplary housing assembly. 
         FIGS. 17-21  are schematic perspective views of parts of exemplary lighting assemblies. 
         FIG. 22  is a schematic perspective view of an exemplary lighting assembly segment. 
         FIGS. 23-29  are schematic perspective views of exemplary lighting assemblies. 
         FIG. 30  is a schematic perspective view of an exemplary lighting assembly segment. 
         FIG. 31  is a schematic side view of parts of an exemplary lighting assembly. 
         FIG. 32  is a schematic top view of the exemplary lighting assembly of  FIG. 31 . 
         FIG. 33  is a schematic perspective view of parts of an exemplary lighting assembly. 
         FIG. 34  is a schematic perspective view of an exemplary lighting assembly segment. 
         FIG. 35  is a schematic perspective view of parts of an exemplary lighting assembly. 
         FIG. 36  is a schematic perspective view of an exemplary light guide assembly. 
         FIGS. 37A-37C  are schematic views of an exemplary light guide assembly. 
         FIGS. 38A-38C  are schematic views of an exemplary light guide assembly. 
         FIG. 39  is a schematic top view of parts of an exemplary lighting assembly. 
     
    
    
     DESCRIPTION 
     Embodiments will now be described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. The figures are not necessarily to scale. Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments. In this disclosure, angles of incidence, reflection, and refraction and output angles are measured relative to the normal to the surface (e.g., the major surface). 
     In accordance with one aspect of the present disclosure, a light guide assembly includes light guide segments, each including: opposed first and second major surfaces extending between a proximal end and a distal end in a length direction, the opposed first and second major surfaces spaced apart from one another in a thickness direction orthogonal to the length direction; and a light input edge extending in the thickness direction between the opposed first and second major surfaces at the proximal end, the first and the second major surfaces configured to propagate light input to the light guide through the light input edge therebetween by total internal reflection. One of the light guide segments includes a first side edge surface extending between the proximal end and distal end and between the opposed first and second major surfaces, the first side edge surface including one or more side edge surface sections, at least a portion of the one or more side edge surface sections oriented non-parallel to the thickness direction. Another of the light guide segments includes a second side edge surface complimentary to the first side edge surface and extending between the proximal end and distal end and between the opposed first and second major surfaces, the second side edge surface including one or more side edge surface sections, at least a portion of the one or more side edge surface sections oriented non-parallel to the thickness direction. The one of the light guide segments is arranged adjacent the another of the light guide segments such that the first side edge surface abuts the complimentary second side edge surface, the one of the light guide segments variably positionable relative to the another of the light guide segments about an axis parallel to the length direction so the light guide assembly curves about the axis parallel to the length direction. 
     In accordance with another aspect of the present disclosure, a housing assembly includes housing segments, each housing segment directly coupled to an adjacently located one of the housing segments, each housing segment including: a housing main body extending in a width direction between a first end and a second end; a retaining portion configured to retain a light guide segment extending in a length direction orthogonal to the width direction; and at least one coupling member configured to directly couple the housing segment to the adjacently located one of the housing segments. One of the housing segments includes a first coupling member. Another of the housing segments includes a second coupling member configured to directly couple to the first coupling member. The one of the housing segments is directly coupled to the another of the housing segments via the first and second coupling members and are variably positionable relative to each other about an axis parallel to the length direction. 
     In accordance with another aspect of the present disclosure, a light guide includes: opposed first and second major surfaces extending between a proximal end and a distal end in a length direction, a light input edge extending between the opposed first and second major surfaces at the proximal end of the light guide, the first and the second major surfaces configured to propagate light input to the light guide through the light input edge therebetween by total internal reflection; a transition area at the proximal end of the light guide; and light guide segments extending from the transition area towards the distal end of the light guide, each one of the light guide segments separated from an adjacent one of the light guide segments by a slot extending in a thickness direction either partially or fully through the light guide. The opposed first and second major surfaces at each light guide segment are planar surfaces. The transition area curves about an axis parallel to the length direction. 
     With initial reference to  FIG. 1 , an exemplary embodiment of a light guide assembly is shown at  100 . The light guide assembly  100  includes light guide segments  102 , which collectively form the light guide assembly  100 . The light guide assembly  100  may also be generally referred to as a light guide. The exemplary light guide assembly  100  shown in  FIG. 1  includes six light guide segments  102 , but in other embodiments the light guide assembly  100  may include any suitable number of light guide segments. Accordingly, in some embodiments, the light guide assembly  100  may be formed of two or more light guide segments  102 . In some embodiments, each light guide segment  102  is in direct contact with one or more adjacently-located light guide segments. In other embodiments, one or more of the light guide segments  102  is spaced apart from one or both of the adjacently-located light guide segments. 
     In discussing the features of the light guide segments  102  herein, reference may be made to a single light guide segment. It will be understood that such description may apply to each of the light guide segments  102  that collectively form the light guide assembly  100 . That is, embodiments of the light guide assembly  100  are contemplated where each of the light guide segments  102  has the same respective feature. Although, in some embodiments, one or more of the light guide segments  102  may differ in one or more of dimension, shape, material, light extraction property, light modification property, and the like. 
     The light guide segment  102  is a solid article of manufacture made from, for example, polycarbonate, poly(methyl-methacrylate) (PMMA), glass, or other appropriate material. In some embodiments, the light guide segment  102  may be a multi-layer component having two or more layers that may differ in refractive index. Each light guide segment  102  includes a first major surface  104  and a second major surface  106  opposite the first major surface  104 . The light guide segment  102  is configured to propagate light by total internal reflection between the first major surface  104  and the second major surface  106 . 
     The light guide segment  102  extends in a length direction  109  between a proximal end  108  and a distal end  110  (e.g., between edge  112  and edge  114 ). The dimension of the major surfaces  104 ,  106  in the length direction  109  is greater, typically ten or more times greater, than the thickness of the light guide segment  102 . The thickness is the dimension of the light guide segment  102  in a direction orthogonal to the major surfaces  104 ,  106 . The thickness of the light guide  102  may be, for example, about 0.1 millimeters (mm) to about 10 mm. The light guide segment  102  also extends in a width direction  111  orthogonal the length direction  109  (e.g., between side edge surfaces  116 ,  118 ). Because the light guide segments collectively form the light guide assembly, in some embodiments, the width of each of the major surfaces  104 ,  106  in the width direction  111  may be less than the length of the major surfaces  104 ,  106  in the length direction  109 . 
     As shown in  FIG. 1 , in some embodiments, the major surfaces  104 ,  106  of the light guide segment  102  are generally rectangular in shape with their length being greater than the width. The particular width and/or length of each light guide segment  102  included in the light guide assembly  100  may depend on factors such as the size of the light guide assembly  100 , the curvature of the light guide assembly  100 , and the like. As an example,  FIG. 2  shows another exemplary embodiment of the light guide segment  102  wherein its width in the width direction  111  is greater than the width of the light guide segment  102  in the width direction  111  shown in  FIG. 1 . In one example, the width of the light guide segment in the width direction  111  may be about 2 inches. In other examples, the light guide segment  102  may be wider or narrower, so long as the respective widths of the light guide segments that form the light guide assembly  100  allow for a desired curvature of the light guide assembly  100 . While not specifically shown, as mentioned above, the dimensions (e.g., width, length, thickness) of the respective light guide segments  102  may vary among the light guide segments  102  that make up the light guide assembly  100  (e.g., depending on the particular configuration of the light guide assembly). 
     At least one edge surface extends between the major surfaces  104 ,  106  of the light guide segment  102  in the thickness direction. The total number of edge surfaces depends on the configuration of the light guide segment  102 . In the case where the light guide segment  102  is rectangular (e.g., as shown in  FIGS. 1 and 2 ), the light guide segment has four edge surfaces  112 ,  114 ,  116 ,  118 . In the embodiment shown, the light guide segment  102  extends in the length direction  109  between edge surface  112  at the proximal end  108  and edge surface  114  at the distal end  110 ; and extends in the width direction  111  between edge surface  116  and edge surface  118 . In this embodiment, the edge surfaces  116  and  118  define the sides of the light guide in the width direction and may also be referred to as side edge surfaces. Other light guide segment shapes result in a corresponding number of edge surfaces. Depending on the shape of the light guide segment  102 , each edge surface may be straight or curved, and adjacent edge surfaces may meet at a vertex or join in a curve. Moreover, each edge surface may include one or more straight portions connected to one or more curved portions. The edge surface through which light from the light source is input to the light guide will now be referred to as a light input edge. In some embodiments of the light guide segments  102  shown in  FIGS. 1 and 2 , the edge surface  112  is a light input edge. In some embodiments, the light guide  102  includes more than one light input edge. For example, in other embodiments of the light guide segments  102  shown in  FIGS. 1 and 2 , both the edge surface  112  and the edge surface  114  are respective light input edges. Furthermore, the one or more light input edges may be straight and/or curved. 
     In the embodiment shown in  FIGS. 1 and 2 , the major surfaces  104 ,  106  of the light guide segment  102  are planar. The light guide segments  102  that form the light guide assembly  100  may be arranged relative to one another in order to form a desired curvature of the light guide assembly  100 . In other embodiments, at least a portion of the major surfaces  104 ,  106  of the light guide segment  102  are curved in one or more directions. In one example, the intersection of the light input edge  112  and one of the major surfaces  104 ,  106  defines a first axis, and at least a portion of the light guide segment  102  curves about an axis parallel to the first axis (e.g., the light guide segment  102  may curve about an axis parallel to the width direction  111 ). In another example, at least a portion of the light guide segment  102  curves about an axis orthogonal to the first axis (e.g., the light guide segment  102  may curve about an axis parallel to the length direction  109 ). Similar to the above-described embodiment, the light guide segments  102  that form the light guide assembly  100  may be arranged relative to one another in order to form a desired curvature of the light guide assembly  100 . As mentioned above, in some embodiments, the respective light guide segments  102  that make up the light guide assembly  100  may each have the same planar or curved shape. In other embodiments, the respective light guide segments  102  that make up the light guide assembly  100  may have different respective planar or curved shapes depending on the particular configuration of the light guide assembly  100 . 
     As shown in the embodiments of  FIGS. 1 and 2 , the side edge surfaces  116 ,  118  each extend between the proximal end  108  and the distal end  110  of the light guide segment  102 . The side edge surfaces  116 ,  118  may be configured to allow for adjacent light guide segments  102  to be arranged in a desired manner so that the light guide assembly  100  has a given curvature (e.g., in the width direction  111 ). The side surface surfaces  116 ,  118  are configured such that the side surface  116  of one of the light guide segments is complimentary to the abutting side edge surface  118  of an adjacently-arranged light guide segment. Accordingly, even where the side surface  116  of one of the light guide segments is in contact with the abutting side edge surface  118  of an adjacent light guide segment, the adjacent light guide segments  102  may still be variably positionable relative to one another about an axis parallel to the length direction  109  so the light guide assembly  100  curves about the axis parallel to the length direction  109 . 
     In some embodiments, one or both of the side edge surfaces  116 ,  118  of the light guide segment  102  includes one or more side edge surface sections that collectively form the side edge surface. At least a portion of the one or more side edge surface section is oriented non-parallel to the thickness direction. The side edge surface section(s) may be straight or curved, and adjacent edge surface sections may meet at a vertex or join in a curve.  FIGS. 1 and 2  show an exemplary embodiment where the side edge surface  116  is embodied as a single side edge surface section extending between the major surfaces  104 ,  106 , the side edge surface section being convex in shape. Also, the side edge surface  118  is embodied as a single side edge surface section extending between the major surfaces  104 ,  106 , the side edge surface section being concave in shape. The light guide segments  102  are configured such that the convex-shaped side edge surface  116  is complimentary to the concave-shaped side edge surface  118  of the adjacent light guide segment, and adjacently-located light guide segments  102  are variably positionable relative to one another about the axis parallel to the length direction  109 .  FIGS. 3-5  are side views of exemplary arrangements of light guide segments  102  having the respective concave and convex side edge surfaces. In  FIG. 3 , the adjacently-located light guide segments  102  are arranged such that the collectively formed light guide assembly  100  is planar. In  FIG. 4 , the adjacently-located light guide segments  102  are arranged such that the collectively formed light guide assembly  100  is curved. In  FIG. 5 , the adjacently-located light guide segments are arranged such that the collectively formed light guide assembly  100  is in the form of an S-bend shape. It is noted that  FIGS. 3-5  show one exemplary embodiment of respective concave and convex side edge surfaces, and that other embodiments of such side edge surface may have different shapes, e.g., different curvatures. While the adjacently-located light guide segments  102  may be arranged in the manner shown in  FIGS. 3-5 , it will be appreciated that the curvature between light guide segments shown therein is for illustrative purposes, and that the amount of curvature between adjacently-located light guide segments and/or the specific orientation of the adjacently-located light guide segments when placed at such curved arrangement may be different in other embodiments. 
     In other embodiments, the respective side edge surfaces of the light guide segments  102  may have other suitable complimentary shapes that allow for adjacently-arranged light guide segments to be variably positionable relative to one another about an axis parallel to the length direction  109  so the light guide assembly curves about the axis parallel to the length direction. As an example,  FIGS. 6-8  show side views of an embodiment where one of the side edge surfaces  116  is shaped as a prismatic element having two planar side edge surface sections  116   a ,  116   b  oriented at respective angles relative to the major surfaces  104 ,  106  that intersect to form a ridge  116   c . The other of the side edge surfaces  118  is shaped complimentary to the prismatic shape in the shape of a v-groove, wherein the side edge surface sections  118   a ,  118   b  are each planar and intersect to form a ridge  118   c . Similar to the embodiment described above in  FIGS. 1-5 , the side edge surfaces  116 ,  118  shown in  FIGS. 6-8  extend between the proximal end and the distal end of the light guide segment  102 , and the light guide segments  102  are configured such that the side edge surface  116  having the prismatic shape of one light guide segment is complimentary to the side edge surface  118  of an adjacently located light guide segment having the v-groove. The complimentary prismatic shapes formed by the side edge surfaces may allow for adjustment of the position of one light guide segment relative to the adjacent light guide segment. In the example shown in  FIGS. 6-8 , the angle formed by the plane surfaces  118   a ,  118   b  that form the v-groove of one light guide segment may be wider than the angle of the prismatic shape formed by the plane surfaces  116   a ,  116   b , and the abutted complimentary surfaces may be adjusted by pivoting the prismatic shape within the v-groove. In  FIG. 6 , the adjacently-located light guide segments  102  are arranged such that the collectively formed light guide assembly  100  is planar. In  FIG. 7 , the adjacently-located light guide segments  102  are arranged such that the collectively formed light guide assembly  100  is curved. In  FIG. 8 , the adjacently-located light guide segments  102  are arranged such that the collectively formed light guide assembly  100  is in the form of an S-bend shape. It is noted that  FIGS. 6-8  show one exemplary embodiment of a prismatic shape and groove side edge surfaces, and that other embodiments of such side edge surface may have different shapes. As an example, in some embodiments (not specifically shown), the angle formed by the plane surfaces  118   a ,  118   b  that form the v-groove of one light guide segment may be nominally the same as the angle of the prismatic shape formed by the plane surfaces  116   a ,  116   b ; and the positioning of the prismatic shape within the groove of the adjacently-located light guide segment may allow for adjustment of the adjacently-arranged light guide segments relative to one another about an axis parallel to the length direction. While the adjacently-located light guide segments  102  may be arranged in the manner shown in  FIGS. 6-8 , it will be appreciated that the curvature between light guide segments shown therein is for illustrative purposes, and that the amount of curvature between adjacently-located light guide segments and/or the specific orientation of the adjacently-located light guide segments when placed at such curved arrangement may be different in other embodiments. 
     Any other suitable complimentary shapes that allow for adjacently-arranged light guide segments to be variably positionable relative to one another about an axis parallel to the length direction  109  are contemplated. For example, although not specifically shown, one or both of the planar surfaces of the side edge surface portions shown in  FIGS. 6-8  may instead be curved about an axis extending parallel to the length direction. In another example, the ridge formed by the side edge surface portions shown in  FIGS. 6-8  may instead be a curved surface such as a bullnose shape. In still other examples, the side edge surfaces may have complimentary edge surfaces formed as half of an octagon, decagon, or the like. In such an embodiment, the adjacent light guide segments may be arranged at one of several preset angles depending on the number of sides provided at the side edge surface. 
     As mentioned above, in some embodiments, the respective light guide segments  102  that make up the light guide assembly  100  may each have the same arrangement of side edge surfaces  116 ,  118  such that both side edge surfaces include one or more side edge surface sections, at least a portion of the one or more side edge surface sections oriented non-parallel to the thickness direction. For example,  FIGS. 1-8  show embodiments where each of the light guide segments  102  includes one side edge surface  116  embodied as a convex or prismatic shape, and also includes another side edge surface  118  embodied as a complimentary concave or prismatic shape. In other embodiments, one or more of the light guide segments may only have one side edge surface that includes one or more side edge surface sections, where at least a portion of the one or more side edge surface sections is oriented non-parallel to the thickness direction. For example, in embodiments of the light guide assembly  100  where the assembly has ends in the width direction, the light guide segments  102  located at the ends in the width direction  111  may each have one side edge surface (e.g., the end surface of the light guide assembly  100 ) that is planar and extends parallel to the thickness direction, or is otherwise not complimentary to a side edge surface of an adjacently-located light guide segment. 
     In some embodiments, the light guide segments  102  are retained in their respective orientations using a housing assembly (described below). Adjacent light guide segments  102  may be in direct contact with each other via their respective side edge surfaces, or may be spaced apart from one another. In some embodiments, the adjacent light guide segments may be coupled to one another by an adhesive and/or resin, e.g., an index matching optical adhesive resin (not shown). The adhesive and/or resin may also hold the light guide segments in a desired arrangement. In still other embodiments, one or more reflectors may be placed between the respective side edge surface of adjacently-located light guide segments. The reflector may have a shape that corresponds to the side edge surface(s) of the light guide segment(s). In some embodiments the reflector may be used alone or together with the housing assembly, adhesive, and/or resin to retain the light guide segments in their respective orientations. 
     With continued reference to  FIG. 1 , in some embodiments the light guide segment  102  includes light extracting elements  120  in, on, or beneath at least one of the major surfaces  104 ,  106 . Light extracting elements  120  that are in, on, or beneath a major surface will be referred to as being “at” the major surface. Each light extracting element  120  functions to disrupt the total internal reflection of the light propagating in the light guide segment and incident thereon. In one embodiment, the light extracting elements  120  reflect light toward the opposing major surface so that the light exits the light guide segment  102  through the opposing major surface. Alternatively, the light extracting elements  120  transmit light through the light extracting elements  120  and out of the major surface of the light guide segment  102  having the light extracting elements  124 . In another embodiment, both types of light extracting elements  120  are present. In yet another embodiment, the light extracting elements  120  reflect some of the light and refract the remainder of the light incident thereon. Therefore, the light extracting elements  120  are configured to extract light from the light guide segment  102  through one or both of the major surfaces  104 ,  106 . 
     Exemplary light extracting elements  120  include features of well-defined shape, such as V-grooves and truncated V-grooves. Other exemplary light extracting elements  120  include micro-optical elements, which are features of well-defined shape that are small relative to the linear dimensions of the major surfaces  104 ,  106 . The smaller of the length and width of a micro-optical element is less than one-tenth of the longer of the length and width (or circumference) of the light guide segment  102  and the larger of the length and width of the micro-optical element is less than one-half of the smaller of the length and width (or circumference) of the light guide segment  102 . The length and width of the micro-optical element is measured in a plane parallel to the major surface  104 ,  106  of the light guide segment  102  for planar light guide segments or along a surface contour for non-planar light guide segment  102 . Other exemplary light extracting elements  120  include features of indistinct shape or surface textures, such as printed features of indistinct shape, ink-jet printed features of indistinct shape, selectively-deposited features of indistinct shape, and features of indistinct shape wholly formed by chemical etching or laser etching. 
     Light extracting elements  120  of well-defined shape (e.g., the above-described grooves and micro-optical elements) are shaped to predictably reflect or refract the light propagating in the light guide segment  102 . In some embodiments, at least one of the light extracting elements  120  is an indentation (depression) of well-defined shape in the major surface  104 ,  106 . In other embodiments, at least one of the light extracting elements  124  is a protrusion of well-defined shape from the major surface  104 ,  106 . The light extracting elements of well-defined shape have distinct surfaces on a scale larger than the surface roughness of the major surfaces  104 ,  106 . Light extracting elements of well-defined shape exclude features of indistinct shape or surface textures, such as printed features of indistinct shape, ink-jet printed features of indistinct shape, selectively-deposited features of indistinct shape, and features of indistinct shape wholly formed by chemical etching or laser etching. 
     The light extracting elements  120  of well defined shape are configured to extract light in a defined intensity profile (e.g., a uniform intensity profile) and with a defined light ray angle distribution from one or both of the major surfaces  104 ,  106 . In this disclosure, intensity profile refers to the variation of intensity with regard to position within a light-emitting region (such as the major surface or a light output region of the major surface). The term light ray angle distribution is used to describe the variation of the intensity of light with ray angle (typically a solid angle) over a defined range of light ray angles. In an example in which the light is emitted from an edge-lit light guide, the light ray angles can range from −90° to +90° relative to the normal to the major surface. Each light extracting element  120  of well defined shape includes at least one surface configured to refract or reflect light propagating in the light guide segment  102  and incident thereon such that the light is extracted from the light guide segment. Such surface(s) is also herein referred to as a light-redirecting surface. 
     The light extracting elements  120  of well defined shape can be any suitable shape. As an example, the light guide segment  102  shown in  FIG. 1  includes micro-optical elements at the major surface  106  configured as v-groove-shaped depressions having an arcuate ridge, hereinafter referred to as “football-shaped” micro-optical elements. A football-shaped micro-optical element resembles the profile of the ball used in American football. Each football-shaped micro-optical element  120  includes a first side edge surface  122  and a second side edge surface  124  that come together to form a ridge  126  having ends that intersect the one of the major surfaces  104 ,  106  at which the micro-optical element  120  is formed. Other exemplary embodiments of the light guide  102  may include micro-optical elements  120  having other suitable shapes. Exemplary micro-optical elements  120  are described in U.S. Pat. No. 6,752,505, the entire content of which is incorporated by reference, and, for the sake of brevity, are not described in detail in this disclosure. 
     In some embodiments, the light extracting elements  120  of well defined shape have the same or nominally the same shape, size, depth, height, slope angle, included angle, surface roughness, and/or index of refraction. The term “nominally” as used herein encompasses variations of one or more parameters that fall within acceptable tolerances in design and/or manufacture. As an example, each of the micro-optical elements  120  may have the same or nominally the same football shape shown in  FIG. 1 . In other embodiments, the light extracting elements  120  of well defined shape may vary in one or more of shape, size, depth, height, slope angle, included angle, surface roughness, and/or index of refraction. This variation in light extracting elements  120  of well defined shape may achieve a desired light output from the light guide over the corresponding major surface(s). 
     In some embodiments, the respective light guide segments  102  that make up the light guide assembly  100  may each have the same or nominally the same type and/or arrangement of light extracting elements. In other embodiments, the presence/absence of light extracting elements, as well as the shape, size, depth, height, slope angle, included angle, surface roughness, and/or index of refraction of the light extracting elements may vary from among the light guide segments that form the light guide assembly. As an example, with reference to  FIG. 1 , the light guide assembly may include an alternating arrangement of light guide segments where one light guide segment includes light extracting elements at its major surface(s) and the adjacently-located light guide segment does not include light extracting elements. The light guide assembly may also include reflectors respectively located between adjacent light guide segments such that light does not cross from one light guide segment to another when propagating in the light guide. Such an arrangement may provide a light guide assembly that when illuminated provides a desired visual effect. Other embodiments of the light guide assembly may have different arrangements of light extracting elements to provide a desired light output (and/or a desired visual effect). 
     Light guide segments  102  are typically formed by a process such as injection molding or extruding. With regard to light extracting elements, in some embodiments, light extracting elements are defined in a shim or insert used for injection molding the light guide segment by a process such as diamond machining, laser micromachining, photolithography, or another suitable process; or any of the above-mentioned processes may be used to define the light extracting elements in a master that is used to make the shim or insert. In other embodiments, the light extracting elements are subsequently formed on one or both of the major surfaces of the light guide segment by a process such as stamping, embossing, or another suitable process. With regard to the side edge surfaces of the light guide segments as described above, in some embodiments, the mold from which the light guide segment is formed is configured to form the side edge surfaces having the desired shape. In other embodiments, the side edge surfaces are formed by a secondary process. In one example, a light guide segment having a rectangular shape in a plane orthogonal to the thickness and parallel to the width direction is formed by injection molding, and the side edge surfaces of the segment are subsequently formed into a desired shape (e.g., using a router or other suitable machining tool). 
     With the increased popularity of LED lighting assemblies, there has also been an increase in the diversity of light guide shapes and sizes utilized therein. As an example, in the area of general lighting, there are many instances where it may be desired to manufacture a lighting fixture having a particular curved shape. In such embodiments, the light guide may be injection molded into the shape of a curved light guide such that the major surfaces of the light guide have a curvature (e.g., a convex shape, concave shape, cylindrical shape, wave shape, S-bend shape, V-bend shape, or any other suitable shape). However, this conventionally requires the use of design-specific tooling. In many situations, this design-specific tooling can be difficult to produce and cost prohibitive. 
     And conventionally it is not possible to injection mold the light guide as a flat panel (e.g., lacking or having a negligible amount of curvature) and subsequently subject it to secondary processing in order to adjust/change its curvature, as this would result in deformation of the micro-optical elements formed at the major surface(s) of the light guide. This would adversely modify and/or destroy the optical characteristic of such micro-optical elements. This is particularly the case when a significant amount of curvature is imparted over the surface of the light guide. 
     In accordance with an approach of the present application, and with exemplary reference to  FIGS. 1-8  described above, a light guide assembly may instead be formed from a collection of two or more light guide segments  102 , wherein the light guide segments  102  have side edge surfaces that are configured such that adjacently-located light guide segments  102  are variably positionable relative to one another. By using several light guide segments having either the same shape, or several light guide segments having one of a selected few number of shapes, a light guide assembly have a desired curvature can be formed. Accordingly, relatively generic tooling can be utilized to form a multitude of light guide shapes. This approach may also allow the light guide assembly to be formed into a desired curved shape without adversely affecting the optical characteristic of its micro-optical elements. 
     As described above, the abutting side edge surfaces of the light guide segments  102  may allow for the adjacent light guide segments  102  to be variably positionable relative to one another about an axis parallel to the length direction  109  so the light guide assembly  100  curves about the axis parallel to the length direction  109  in a desired arrangement.  FIGS. 9A-9G  show exemplary arrangements of such light guide assemblies.  FIG. 9A  shows a light guide assembly in the form of a curved convex or concave shape.  FIG. 9B  shows a light guide assembly in the form of a cylindrical shape.  FIG. 9C  shows a light guide assembly in the form of a square having rounded corners.  FIG. 9D  shows a light guide assembly in the form of a S-bend or “wave” shape.  FIG. 9E  shows a light guide assembly in the form of a rectangle having rounded corners.  FIG. 9F  shows a light guide assembly in the form of a triangle having rounded corners.  FIG. 9G  shows a light guide assembly having a combination of a rectangular and a wave shape. By utilizing the light guide segments, any other suitable arrangement may be achieved. 
     With additional reference to  FIGS. 10-12 , the light guide assembly may be included as part of a lighting assembly  200 . As shown, the lighting assembly includes a light source  202  located adjacent to the respective light input edges of the light guide segments  102 . 
     The light source  202  is configured to edge light the light guide segment  102  such that light from the light source  202  enters the light input edge and propagates along the light guide segment  102  by total internal reflection at the major surfaces  104 ,  106 . In embodiments where the light guide segment  102  includes more than one light input edge, the lighting assembly  100  may include a corresponding number of light sources  202 . As shown for example in  FIG. 11 , the lighting assembly  200  may include a first light source  202   a  adjacent the light input edge  112 , and a second light source  202   b  adjacent the light input edge  114 . The first and second light sources  112   a ,  112   b  may be collectively referred to as light source  112 . 
     The light source  202  includes one or more solid-state light emitters  204 . The solid-state light emitters  204  constituting the light source  202  are arranged linearly or in another suitable pattern depending on the shape of the light input edge of the light guide segment  102  to which the light source  202  supplies light. Exemplary solid-state light emitters  204  include such devices as LEDs, laser diodes, and organic LEDs (OLEDs). In an embodiment where the solid-state light emitters  204  are LEDs, the LEDs may be top-fire LEDs or side-fire LEDs, and may be broad spectrum LEDs (e.g., white light emitters) or LEDs that emit light of a desired color or spectrum (e.g., red light, green light, blue light, or ultraviolet light), or a mixture of broad-spectrum LEDs and LEDs that emit narrow-band light of a desired color. In one embodiment, the solid-state light emitters  204  emit light with no operably-effective intensity at wavelengths greater than 500 nanometers (nm) (i.e., the solid-state light emitters  204  emit light at wavelengths that are predominantly less than 500 nm). In some embodiments, the solid-state light emitters  204  constituting light source  202  all generate light having the same nominal spectrum. In other embodiments, at least some of the solid-state light emitters  204  constituting light source  202  generate light that differs in spectrum from the light generated by the remaining solid-state light emitters  204 . For example, two different types of solid-state light emitters  204  may be alternately located along the light source  202 . 
     The number of solid-state light emitters adjacent the light input edge of a given light guide segment  102  may be at least in part dependent on the dimensions of the light guide segment and/or the dimensions and spacing of the solid-state light emitter  204 . For example,  FIG. 10  shows an example where one sold-state light emitter  204  is adjacent the light input edge  112  for a given light guide segment.  FIG. 12  shows another example where the width of the light guide segments is greater than the width shown in  FIG. 10 , and where more than one solid-state light emitter  204  is adjacent each light input edge  112  of each light guide segment  102 . 
     The lighting assembly  200  may include one or more additional components. For example, although not specifically shown, in some embodiments of the lighting assembly, the light source includes structural components to retain the solid-state light emitters. In the examples shown in  FIGS. 10-12 , the solid-state light emitters  204  are mounted to a printed circuit board (PCB)  206 . The light source  202  may additionally include circuitry, power supply, electronics for controlling and driving the solid-state light emitters  204 , and/or any other appropriate components. 
     The lighting assembly  200  may additionally include a housing for retaining the light source and the light guide assembly. The housing may retain a heat sink or may itself function as a heat sink. With additional reference to  FIGS. 13-16 , the lighting assembly  200  includes a housing embodied as a housing assembly  300  having housing segments  302 . In some embodiments, each housing segment  302  is associated with a respective light guide segment  102  and is located at the light input edge of the light guide segment (e.g., at the edge surface  112  as shown in the exemplary embodiment of  FIG. 13 ). 
       FIG. 14  shows a single instance of a light guide segment  102  retained by a single instance of a housing segment  302 , which may be referred to as a lighting assembly segment  206 . The housing segments  302  may be connected to one another and oriented such that the lighting assembly segments  206  that form the lighting assembly are arranged and retained in a particular arrangement. Collectively, the housing segments  302  may retain the light guide assembly  100  in a desired arrangement. Any suitable number of lighting assembly segments  206  may be coupled together to form the lighting assembly  200 . 
     In discussing the features of the housing segments  302 , reference may be made to a single housing segment. It will be understood that such description may apply to each of the housing segments  302  that collectively form the housing assembly  300 . That is, embodiments of the housing assembly  300  are contemplated where each of the housing segments  302  has the same respective feature. Although, in some embodiments, the housing segments  302  may differ in one or more of dimension, shape, material, and the like. 
     With specific reference to  FIG. 15 , the housing segment  302  includes a main body portion  304  that extends in the width direction  111  between a first end  306  and a second end  308 . The housing segment  302  includes coupling member  310  at its first end  306 , and includes coupling member  312  at its second end  308 . The coupling members  310 ,  312  are configured to directly couple adjacent housing segments  302  to one another. In the example shown, the coupling members  310 ,  312  are embodied as key and slot coupling members, respectively. One of the coupling members  310  includes a single protrusion (e.g., the key), and the other of the coupling members  312  includes a plurality of protrusions spaced apart from one another in a manner that allows the single protrusion of an adjacent housing segment to be inserted therein (e.g., the slot). As specifically shown in  FIGS. 13 and 15 , the coupling members of the housing segments  302  are arranged such that the key of one coupling member may mate with the slot of an adjacent coupling member (e.g., the single protrusion of one heat sink portion is interleaved with the plurality of protrusions of an adjacent heat sink portion). 
     The key and slot are oriented such that the housing segments  302  (and hence the light guide segments  102 ) may be adjusted and arranged in a particular arrangement relative to one another to provide a lighting assembly having a desired arrangement. For example, in the embodiments shown in  FIGS. 13-16 , the axis on which the interleaved coupling members  310 ,  312  pivot may be the same axis about which the side edge surfaces of the adjacently-located light guide segments  102  coupled to the respective housing segments  302  are variably positioned. Adjustment of two adjacently-coupled housing segments  302  results in a corresponding adjustment of the light guide segments  102 . 
     In some embodiments, frictional force between the coupling members  310 ,  312  (e.g., between the key and slot) may retain the housing segments  302  in a particular arrangement once adjusted. In other examples, the coupling members  310 ,  312  (e.g., the key and slot) may have a through-hole that allows a fastening member such as a screw to be passed therethrough and tightened. In other examples, the particular arrangement of the housing segments  302  may be retained using one or more additional mechanical fasteners (not shown) together with the coupling members  310 ,  312  (e.g., the key and slot). In still other examples, the housing segments are disposed in a shroud (e.g.,  FIGS. 23-29 ) and the shroud retains the housing segments  302  and associated light guide segments  102  in a particular arrangement. 
     The coupling members  310 ,  312  may be configured in any other suitable manner that allows for the housing portion  302  to be coupled with an adjacent housing portion and adjusted to a particular arrangement. For example, in some embodiments, each coupling member may include more than one protrusion, and the respective protrusions of adjacent housing segments may be interleaved with one another. In other embodiments, the coupling members may be configured as another suitable hinge mechanism. Examples include one or more springs or a resilient material that is directly coupled to respective ends of the adjacently-located housing segments and that allows the housing segments to be variably positioned relative to one another (e.g., about the axis extending parallel to the length direction  109 ). In still other embodiments, the coupling members may be configured as magnetic coupling members (e.g.,  FIGS. 34 and 35 ). The magnetic couplers may couple adjacent housing portions to one another by magnetic force once the adjacent housing portions are brought together. 
     The housing segment includes a retaining portion  314 . In the example shown, the retaining portion  314  is embodied as a channel that is configured to receive a light guide segment  102 . The channel extends in the width direction  111  between the first end  306  and the second end  308  of the housing segment  302 . One or more solid-state light emitters  204  (e.g., that form the light source  202  together with any additional solid-state light sources from other connected housing segments) may be retained by the housing segment  302  in the retaining portion  314 . The one or more solid-state light emitters  204  may be arranged such that it is adjacent the light input edge of the light guide segment  102  when the light guide segment is retained by the housing segment (e.g., when the light guide segment is disposed in the channel). In the example shown, as retained by the housing segment  302 , one of the side edge surfaces  116  of the light guide segment  102  is proximate the first end  308  of the housing segment, and the other of the side edge surfaces  118  of the light guide segment  102  is proximate the second end  306  of the housing segment. In some examples, the light guide segment  102  is mechanically fastened to the retaining portion  314 . As shown in the illustrated example, the retaining portion may include one or more holes  316  through which a mechanical fastener such as a screw or pin may be inserted. In such example, the light guide segment  102  may have corresponding hole (not shown) through which the fastener may pass once the light guide segment is inserted in the channel, or the light guide may not have a corresponding hole and the fastener may instead press against the major surface of the light guide segment  102 . In other embodiments, the light guide segment  102  may be fastened to the retaining portion via an adhesive, and/or may be retained by a compressive force from the walls that define the channel of the retaining portion  314 . 
     As described above, the light source  202  may include components such as structural components to retain the solid-state light emitters, circuitry, power supply, electronics for controlling and driving the solid-state light emitters  204 , and/or any other appropriate components. As the light source  202  is retained by the housing segments, the housing segment  302  may include these components. In some embodiments, the housing segments  302  may be electrically coupled to one another. In an example, the coupling members  310 ,  312  of the housing segment include electrical contacts for coupling electrical power to/from an adjacent housing segment. Accordingly, electrical power from a single power source may power light sources retained in multiple housing segments. In other embodiments, one or more wires may extend from the respective housing segments  302  that may be used to electrically couple the light emitters (e.g., to a power source, to a controller, and/or to one another). These wires may be covered, e.g., using a shroud (described below). 
     As described above, the housing segments  302  that make up the housing assembly  300  may be adjusted and/or positioned relative to one another so that the light guide segments  102  forming the lighting assembly  100  that are respectively retained by the housing segments  302  are arranged in a particular arrangement.  FIGS. 17-19  show exemplary arrangements of the lighting assembly. More specifically,  FIG. 17  shows one exemplary arrangement of a lighting assembly  100  in a curved, semi-cylindrical arrangement.  FIG. 18  shows another exemplary arrangement of the lighting assembly  200  having a wave arrangement (an S-bend).  FIG. 19  shows another exemplary arrangement of the lighting assembly  200  having a cylindrical arrangement.  FIG. 19  exemplifies that the housing segments (as well as the light guide segments) allow for the ends of the lighting assembly  200  to be joined together to form a continuous shape. 
     The embodiments of the lighting assembly  200  shown in  FIGS. 17-19  include a housing assembly  300  at the proximal end of the light guide assembly. That is, in such embodiments, the distal end of the light guide assembly does not include a housing assembly. In other embodiments, the lighting assembly may include a plurality of housing assemblies  300 , one  300   a  at the proximal end of the light guide assembly  100  and another  300   b  at the distal end of the light guide assembly  100 .  FIGS. 20 and 21  shows show exemplary arrangements of the lighting assembly  200  including a first housing assembly  300   a  at the proximal end of the light guide assembly  100  and a second housing assembly  300   b  at the distal end of the light guide assembly  100 .  FIG. 20  shows one exemplary arrangement of a lighting assembly  200  in a curved, semi-cylindrical arrangement.  FIG. 21  shows another exemplary arrangement of the lighting assembly  200  having a wave arrangement (an S-bend). By including the plurality of housing assemblies, the light guide assembly can be retained from both the proximal end and the distal end thereof. The light guide segments can also be edge lit from both edge surfaces (e.g., edge surfaces  112  and  114 ). 
     With additional reference to  FIG. 22 , an exemplary lighting assembly segment  206  is shown. Multiple instances of the lighting assembly segment  206  may be coupled to one another (e.g., in the manner shown in  FIGS. 20 and 21 ) to form the lighting assembly  200 . The lighting assembly segment  206  includes a light guide segment  102 , a first housing segment at the proximal end  108  of the light guide segment  102 , and a second housing segment at the distal end  110  of the light guide segment  102 . Similar to the embodiments described above, the housing segments  302  of adjacently located lighting assembly segments  206  may be adjusted and/or positioned relative to one another so that the light guide segments  102  forming the lighting assembly  200  are arranged and retained in a particular arrangement. 
     In some embodiments, a shroud  210  (e.g., a bezel) may surround the housing assembly.  FIGS. 23-29  show additional exemplary arrangements of the lighting assembly including a shroud  210 . In some embodiments, the shroud  210  is provided for aesthetic purposes, e.g., to cover the housing segments. In other embodiments, as described above, the shroud  210  may assist in retaining the housing segments  302  in a desired arrangement. In other embodiments, the shroud  210  may assist in mounting/retaining the lighting assembly  200  to a wall, ceiling, or other structure. 
     The shroud  210  may be provided in any suitable arrangement, and the particular shape of the shroud  210  may correspond to the overall shape/curvature of the lighting assembly.  FIG. 23  shows an exemplary arrangement of a lighting assembly  200  in a curved, semi-cylindrical arrangement, where the shroud is also provided in a curved, semi-cylindrical arrangement surrounding the housing assembly.  FIG. 24  shows an exemplary arrangement of a lighting assembly  200  having a cylindrical arrangement, where the shroud is also provided in a cylindrical shape surrounding the housing assembly. In other embodiments, the shape of the shroud  210  may correspond to the curvature of the housing assembly. In each of the embodiments, the shroud  210  may cover the housing assembly  300  but allow for the light guide assembly  100  to be exposed in its desired arrangement. In some embodiments, the shroud  210  may function as a heat sink. 
     In some embodiments, the lighting assembly may include more than one shroud. As an example,  FIG. 25  shows an exemplary embodiment of the lighting assembly  200  similar to the embodiment shown in  FIG. 20 . The embodiment shown in  FIG. 25  includes two shrouds  210   a ,  210   b , each shroud associated with a respective one of the housing assemblies. 
     In some embodiments, a single shroud may retain more than one lighting assembly.  FIG. 26  shows an exemplary embodiment in which the assembly is provided in an elliptical arrangement (e.g., a football shape). In some embodiments, a single lighting assembly may be arranged in this elliptical shape. But in other embodiments, two lighting assemblies may be curved and retained relative to one another to form the overall elliptical shape. In either of these situations, the shroud  210  may retain the lighting assembly or lighting assemblies in the desired elliptical arrangement. For example, when two lighting assemblies are used, the shroud  210  may retain both of the lighting assemblies such that the elliptical arrangement is formed.  FIG. 27  shows another exemplary embodiment in which the shroud  210  retains two lighting assemblies arranged in opposing curved, semi-cylindrical arrangements.  FIG. 28  shows another exemplary embodiment in which the arrangement of light guide segments  102 , whether coupled together as single light guide assembly, or provided as two or more light guide assemblies, may be retained by shroud  210 . 
     While in some embodiments the housing segments  302  (and lighting assembly segments) may be coupled in series (e.g., one coupling member of one housing segment directly coupled to one coupling member of an adjacent housing segment),  FIG. 28  also illustrates that in some embodiments a housing segment  302  may be coupled in parallel to more than one adjacent housing segment. For example, the coupling member at the first and/or second end of the housing segment  302  may be configured in a manner (e.g., in a key and slot arrangement or having a magnetic configuration) that allows two or more adjacent housing segments to be coupled to that respective end. 
     The lighting assembly  200  may include one or more additional components. For example,  FIG. 29  shows an exemplary embodiment of a lighting assembly including a connecting member  220  that extends between a first shroud  210   a  and a second shroud  210   b . The connecting member may serve as a bracket for mounting the lighting assembly to a surface, e.g., a ceiling or a wall. As an example, the lighting assembly may be hung from a ceiling using the connecting member. In other embodiments, the lighting assembly  200  includes any other suitable bracket(s), cable(s), wire(s), stand(s), and/or the like to mount the lighting assembly to a retaining structure (e.g., a ceiling, a wall, stand, etc.). 
     In some embodiments, the lighting assembly  200  may additionally include a reflector (not shown) adjacent one of the major surfaces  104 ,  106  of the light guide segments. Exemplary reflectors include full reflectors and partial reflectors. Use of the reflector may help to control the amount of light emitted, e.g., in upward and downward directions from the lighting assembly. The light extracted through the major surface adjacent the reflector may be reflected by the reflector, re-enter the light guide segment  102  at the major surface, and be output from the light guide segment  102  through the other major surface. 
     In the embodiments described above, the coupling members of the housing segments may be arranged such that adjacently-located and coupled housing segments (e.g., as well as the light guide segments retained by the respective housing segments) may be positioned/adjusted relative to one another about an axis parallel to the length direction  109 . As exemplified in the figures described above, the respective coupling members may be embodied as key and slot coupling members oriented nominally orthogonal to the length direction. In other embodiments, the coupling members of the housing segments may be configured such that the adjacently-located and coupled housing segments may be positioned/adjusted relative to one another in a different manner. In some embodiments, such housing segments may be used together with different shaped light guide segments in order to provide a lighting assembly having a desired shape. 
       FIGS. 30-32  show an exemplary embodiment of a lighting assembly  200  where the housing segments have coupling members  310 ,  312  configured to couple adjacent housing segments  302  to one another, wherein the respective coupling members of the housing segments may be configured to adjust/arrange the housing portions (and the light guide segments) about an axis extending non-parallel and non-orthogonal to the length direction  109 . With specific reference to  FIG. 30 , an exemplary embodiment of a lighting assembly segment  206  is shown including a housing segment  302  having key and the slot coupling members  310 ,  312  oriented at a non-parallel and non-orthogonal angle relative to the length direction  109 . The light guide segment is trapezoidal in shape such that the side edge surfaces  116 ,  118  extend nominally orthogonal to the key and slot coupling members. 
       FIGS. 31 and 32  show an example in which multiple instances of the lighting assembly segment shown in  FIG. 30  form the shape of a truncated cone. The axis on which the interleaved coupling members of adjacent housing segments pivot may be the same axis about which the side edge surfaces of the adjacently-located light guide segments coupled to the respective housing segments are variably positioned. Adjustment of two adjacently-coupled housing segments results in a corresponding adjustment of the light guide segments. 
       FIG. 33  shows another exemplary embodiment of a lighting assembly  200  where the housing segments include coupling members  310 ,  312  configured to couple adjacent housing segments  302  to one another, wherein the respective coupling members of the housing segments may be configured to adjust/arrange the housing portions (and the light guide segments) about an axis extending orthogonal to the length direction  109  and orthogonal to the width direction  111 . As shown, the key and the slot coupling members  310 ,  312  are oriented nominally parallel to the length direction for a given lighting assembly segment  206 . By adjusting the relative position of the adjacently-coupled housing segments  302 , the spacing of the light guide segments  102  may be adjusted in the plane defined by the length direction  109  and width direction  111 . As shown in the exemplary embodiment of  FIG. 33 , the relative position of the adjacently-coupled housing segments may be set such that the side edge surfaces of adjacent light guide segments are in contact with one another. In  FIG. 33 , the light guide assembly collectively forms an annular disk shape. The housing segments  302  can be oriented relative to one another to bring the side edge surfaces into contact with the light guide associated with an adjacent light guide and thereby create what appears as a monolithic light guide. In other embodiments, the relative position of the adjacently-coupled housing segments  302  may be set such that there is a space between the side edge surfaces of adjacent light guide segments  102 . The positioning/spacing of the light guide segments may depend on factors such as the shape of the light guide segment, the relative position of the adjacently-coupled housing segments, and the like. 
     In some of the embodiments described above, the light guide segments  102  that form the light guide assembly  100  have planar major surfaces  104 ,  106 , and the housing segments  302  that form the housing assembly  300  have a planar main body portion. As described above, while the surfaces of the light guide segment and housing segment may be planar, the orientation of the adjacently-located light guide segments and housing segments may be variably positionable such that the light guide assembly formed therefrom includes a curvature. 
     In some embodiments, one or more of the light guide segments and/or one or more of the housing segments may be curved. In some implementations, the curvature of the light guide segment and housing segment may assist in providing a desired curvature/shape to the overall lighting assembly. For example, the lighting assembly may include one or more curved lighting assembly segments and/or one or more planar lighting assembly segments, and the relative positioning of these lighting assembly segments as coupled together may form a lighting assembly having a desired curved shape. Reference is made to  FIGS. 9A-9G  as showing exemplary lighting assembly shapes that can be formed using a limited number of types of shapes (e.g., all planar shapes, all curved shapes, or a mixture of planar and curved shapes). This modular approach of providing a lighting assembly allows a lighting assembly of a desired shape to be more readily produced and in a more economical manner. 
     Expanding this modular assembly concept to other embodiments of a lighting assembly, in some implementations, the curvature of an assembled lighting assembly can be established simply by the curvature of segments themselves (e.g., absent further adjustment of the relative positioning of the adjacently-located light guide segments). The lighting assembly may include one or more curved lighting assembly segments and/or one or more planar lighting assembly segments, and adjacent housing segments may be coupled together via their respective coupling members such that the side edge surface of one light guide segment abuts and is fixed in place relative to the side edge surface of an adjacent light guide segment. 
       FIG. 34  shows an example of a curved lighting assembly segment  206  that exemplifies this modular concept. As shown, the major surfaces  104 ,  106  of the light guide segment  102  are curved about an axis extending parallel to the length direction  109 . The main body portion  304  of the housing segment  302  also curves about an axis extending parallel to the length direction. 
     In the embodiment shown in  FIG. 34 , the coupling members  310 ,  312  are embodied as magnetic connection members. The coupling members may also provide an electric connection between adjacently connected housing segments. In other embodiments, the housing segment may have coupling members similar to those described above (e.g., key and slot coupling members). In still other embodiments, the housing segments may be retained adjacent to one another by a shroud. 
     In the embodiment shown in  FIG. 34 , the side edge surfaces  116 ,  118  of the light guide segment  102  are planar surfaces extending in the thickness direction between the major surfaces. With further reference to  FIG. 35 , which shows an exemplary embodiment of a lighting assembly  200  in the form of a cylindrical shape formed from lighting assembly segments  206  similar to those shown in  FIG. 34 , the adjacent housing segments  302  are coupled together and the respective side edge surfaces  116 ,  118  of the adjacent light guide segments  102  abut and are fixed in place relative to one another. In other embodiments, the side edge surfaces  116 ,  118  may include corresponding side edge surface portions similar to those described above, wherein at least a portion of the one or more side edge surface section is oriented non-parallel to the thickness direction. 
     In other embodiments, the lighting assembly  200  may include one or more curved lighting assembly segments and/or one or more planar lighting assembly segments, and the specific combination of these lighting assembly segments as coupled together may form the lighting assembly having a desired curved shape. Reference is again made to  FIGS. 9A-9G  as showing exemplary lighting assembly shapes that can be formed using a limited number of types of shapes (e.g., all planar shapes, all curved shapes, or a mixture of planar and curved shapes). 
     Turning now to  FIG. 36 , another exemplary embodiment of a light guide assembly is shown at  400 . The light guide assembly  400  is a monolithic light guide that may be locally thermoformed to produce a light guide having a curved shape. 
     Similar to the light guide segment  102 , the light guide assembly  400  is a solid article of manufacture made from, for example, polycarbonate, poly(methyl-methacrylate) (PMMA), glass, or other appropriate material. In some embodiments, the light guide assembly  400  may be a multi-layer component having two or more layers that may differ in refractive index. The light guide assembly  400  includes a first major surface  404  and a second major surface  406  opposite the first major surface  404 . The light guide assembly  400  is configured to propagate light by total internal reflection between the first major surface  404  and the second major surface  406 . The light guide assembly  400  extends in a length direction  109  between a proximal end  408  and a distal end  410  (e.g., between edge  412  and edge  414 ) along a length direction  109  of the light guide assembly  400 ; and extends in a width direction  111  orthogonal to the length direction  109  (e.g., between side edge surfaces  416 ,  418 ). The length and width dimensions of each of the major surfaces  404 ,  406  are greater, typically ten or more times greater, than the thickness of the light guide assembly  400 . The thickness of the light guide assembly  400  may be, for example, about 0.1 millimeters (mm) to about 10 mm. 
     At least one edge surface extends between the major surfaces  404 ,  406  of the light guide assembly  400  in the thickness direction. The total number of edge surfaces depends on the configuration of the light guide. In the example shown, the light guide assembly is rectangular and has four edge surfaces  412 ,  414 ,  416 ,  418 . Other light guide assembly shapes result in a corresponding number of side edge surfaces. Depending on the shape of the light guide assembly  400 , each edge surface may be straight or curved, and adjacent edge surfaces may meet at a vertex or join in a curve. Moreover, each edge surface may include one or more straight portions connected to one or more curved portions. The edge surface through which light from the light source is input to the light guide will now be referred to as a light input edge. In the embodiment shown in  FIG. 36 , the edge surface  412  is a light input edge. In some embodiments, the light guide assembly includes more than one light input edge (e.g., edge surfaces  412  and  414 ). Furthermore, the one or more light input edges may be straight and/or curved. 
     The light guide assembly  400  includes respective transition areas  420   a ,  420   b  at the proximal end  408  and the distal end  410  of the light guide. Light guide segments  422  extend in the length direction  109  between the respective transition areas  420   a ,  420   b , the light guide segments  422  separated by respective slots  424 . As described above, the light guide assembly  400  may be a monolithic light guide, but a solid or dotted line is used in the figures in order to illustrate the respective transition areas and light guide segments. In some embodiments, the slots  424  extend fully through the light guide assembly  400  in the thickness direction of the light guide (i.e., between the major surfaces  404 ,  406 ). In other embodiments (not shown), the slots  424  extend partially through the light guide in the thickness direction. In some embodiments, the portion of the major surfaces of the light guide assembly  400  forming each light guide segment  422  is nominally planar or possesses only a slight amount of curvature, while the portion of the major surfaces of the light guide assembly forming each transition area  420   a ,  420   b  may be at least partially curved (e.g., about an axis parallel to the length direction  109 ). 
     The width of the light guide segments  422  and the width of the slots  424  are less than the width of the light guide assembly  400 . In an example, each light guide segment  422  may be 2 inches, and each slot  424  may be 0.25 inches. In other examples, the light guide segments  422  and slots  424  may be wider or narrower, so long as their widths facilitate the below-described curving of the light guide assembly. In some embodiments, each light guide segment  422  has approximately the same width and each slot  424  has approximately the same width. In other embodiments, the width of the light guide segments  422  may vary and/or the width of the slots  424  may vary depending on the particular configuration of the light guide assembly. 
     Light extracting elements  120  (e.g., micro-optical elements) may be present at at least one of the major surfaces, more specifically at the portion of the major surface(s) that define the light guide segments. In some embodiments, light extracting elements  120  may also be included at at least one of the major surfaces in one or both of the transition areas. 
     The light guide assembly  400  exemplified in  FIG. 36  is rectangular in shape, and has approximately a 1×4 configuration. It will be appreciated that the light guide assembly may have any other suitable geometry (e.g., 1×2, 2×2, 2×4, etc.). Furthermore, while the light guide assembly  400  shown in  FIG. 36  includes two transition areas, in some embodiments, the light guide assembly  400  only includes one transition area (e.g., the light guide segments and slots may extend from the one transition area to the opposite end edge). 
     With additional reference to  FIGS. 37A-37C and 38A-38C , the light guide assembly  400  may be formed by forming a planar light guide and subsequently subjecting the transition areas of the planar light guide to secondary processing. More specifically,  FIG. 37A  shows a top view and  FIGS. 37B and 37C  show respective side views of a light guide assembly  400  having planar major surfaces  404 ,  406 . Similar to the description set forth above with respect to the light guide segment  102 , the light guide assembly  400  may be formed by a process such as injection molding or extruding. The light extracting elements may be defined in a shim or insert used for injection molding the light guide segment. In some embodiments, the mold from which the light guide assembly is formed may include a pattern to allow for formation of the slots  424  and light guide segments  422  extending between the first and second transition areas  420   a ,  420   b . In other embodiments, the light guide assembly formed via injection molding does not include the slots, and the slots are subsequently formed in the light guide assembly (e.g., using a laser or other suitable machining process). If the slots are subsequently formed in the light guide assembly, the slots may be formed prior to the below-described curving process. 
       FIG. 38A  shows a top view and  FIGS. 38B and 38C  show respective side views of a light guide assembly  400  in which the transition areas  420   a ,  420   b  are curved (e.g., about an axis parallel to the length direction  109 ). To form the light guide assembly shown in  FIGS. 38A-38C , the planar light guide is curved by subjecting the transition areas  420   a ,  420   b  to secondary processing. In an example, localized thermoforming may be performed on the transition areas  420   a ,  420   b  of the light guide assembly, during which time the transition areas  420   a ,  420   b  are formed to the desired curvature (e.g., via rolling, vacuum forming, pressing, or another suitable process). Because the widths of the light guide segments  422  are less than the width of the light guide assembly and because they are separated by the slots  424 , curving the transition area  420   a ,  420   b  can be performed without curving or with curving the light guide segment only a negligible amount. Accordingly, the thermoforming process can be localized to the transition areas  420   a ,  420   b . By localizing the thermoforming process on the transition areas  420   a ,  420   b , the light extracting elements (e.g., micro-optical elements) present at the light guide segments  422  may not be deformed. 
     This formation method may allow for the use of either conventional tooling or a single configuration of tooling in order to form several configurations of curved light guide assemblies  400 . For example, the light guide assembly  400  may be formed into, for example, a convex shape, concave shape, cylindrical shape, wave shape, S-bend shape, V-bend shape, or any other suitable shape. This avoids the situation where specific tooling must be created for each individual application. 
     With additional reference to  FIG. 39 , in some embodiments, the light guide assembly  400  may be included as part of a lighting assembly  500 . As shown in  FIG. 39 , the lighting assembly  500  may include a light source  202  positioned adjacent the light input edge. In the exemplary embodiment shown in  FIG. 39 , a first light source  202  is located adjacent the edge surface  412  and is configured to edge light the light guide assembly  400 ; and a second light source  202   b  is located adjacent the edge surface  414  and is configured to edge light the light guide assembly. The light source may include one or more solid-state light emitters  204  similar to that described above. The solid-state light emitters  204  constituting the light source may be arranged in a suitable pattern depending on the shape of the light input edge of the light guide to which the light source supplies light. 
     The lighting assembly may include one or more additional components. For example, the solid-state light emitters  204  are shown as being mounted to a printed circuit board (PCB)  206 . Although not specifically shown, the light source may include circuitry, power supply, electronics for controlling and driving the solid-state light emitters, and/or any other appropriate components. The lighting assembly  500  may additionally include a housing for retaining the light source and the light guide. The housing may retain a heat sink or may itself function as a heat sink. In some embodiments, the lighting assembly includes shroud and/or a mounting mechanism (not shown) to mount the lighting assembly to a retaining structure (e.g., a ceiling, a wall, etc.). 
     In this disclosure, the phrase “one of” followed by a list is intended to mean the elements of the list in the alterative. For example, “one of A, B and C” means A or B or C. The phrase “at least one of” followed by a list is intended to mean one or more of the elements of the list in the alterative. For example, “at least one of A, B and C” means A or B or C or (A and B) or (A and C) or (B and C) or (A and B and C).