Abstract:
A lighting device including a circuit substrate; a plurality of light sources disposed on the circuit substrate; a reflection layer disposed on the circuit substrate, the reflection layer comprising a plurality of openings where respective light sources are located; a plurality of absorbers disposed at an edge of the reflection layer and at an inclination with respect to the reflection layer, wherein the plurality of absorbers have a greater density at first areas aligned with the respective light sources than at second areas between the first areas; and an optical sheet disposed on the light sources.

Description:
[0001]    This application is a Continuation of co-pending U.S. patent application Ser. No. 14/161,284, filed on Jan. 22, 2014, which claims the benefit of priority pursuant to 35 U.S.C. § 119(a) to Korean Patent Application No. 10-2013-0007294, filed on Jan. 23, 2013, which are hereby incorporated by reference as fully set forth herein in their entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a planar lighting device and more particularly, to a planar lighting device including a light emitting device. 
         [0004]    2. Discussion of the Related Art 
         [0005]    Liquid crystal displays (LCDs) which are one type of displays are used in a variety of monitors for televisions, notebook computers and desktops as well as cellular phones. 
         [0006]    Such an LCD does not self-emit light, thus requiring a light-emitting device to light a liquid crystal panel so as to display image information. 
         [0007]    A light emitting device of LCDs is bonded to a rear surface of a liquid crystal panel and is thus referred to as a backlight unit. This backlight unit forms a uniform surface light source and supplies light to a liquid crystal panel. 
         [0008]    A light emitting diode (LED) has a structure in which an n-type semiconductor layer, a light-emitting layer and a p-type semiconductor layer are stacked in a substrate and an electrode is formed on the p-type semiconductor layer and the n-type semiconductor layer. Regarding a principle of light generation by the light emitting diode, light of the light-emitting layer generated upon recombination between holes and electrons injected from respective semiconductor layers is discharged to the outside. 
         [0009]    Such a light emitting diode constitutes a light emitting diode package which is used as a light source of a backlight unit (BLU). 
         [0010]    Such a backlight unit provides a planar light source toward the liquid crystal panel, which is thus considered to be an example of a planar lighting device. The planar lighting device is considered to be a light source which uniformly emits light through a flat surface and has a relatively small thickness. 
         [0011]    The planar lighting device improves luminous efficacy of a display device and accomplishes structural slimness thereof. 
         [0012]    When the light emitting diode is used as a light source of a planar lighting device, the light emitting diode may be a side type in which light is diffused to a side direction or a direct type in which light is emitted in a front direction. A method for uniformly diffusing light emitted from the light emitting diode is required. 
       SUMMARY OF THE INVENTION 
       [0013]    Accordingly, the present invention is directed to a planar lighting device that substantially obviates one or more problems due to limitations and disadvantages of the related art. 
         [0014]    An object of the present invention is to provide a direct-type planar lighting device which improves an edge luminance uniformity of the planar lighting device. 
         [0015]    Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
         [0016]    To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a planar lighting device includes a plurality of light sources arranged on a first surface of a circuit substrate, the light sources mounted thereon, a light regulator disposed in an edge of the first surface, the light regulator regulating luminance difference caused by difference in distance between a plurality of light sources close to the edge, and an optical sheet disposed on the light sources. 
         [0017]    The light regulator may include one or more reflectors for reflecting light emitted from the light sources to an inside or an upper part of an area defined by the first surface. 
         [0018]    The reflectors may be discontinuously disposed in portions of the edge far from the light sources. 
         [0019]    The reflectors may be discontinuously disposed in portions of the edge corresponding to areas between adjacent light sources close to the edge. 
         [0020]    Each reflector may include a reflection plate or a reflection structure contacting the edge. 
         [0021]    The reflection plate or the reflection structure may have a curved cross-sectional shape including a semi-circular, oval or circular arc shape or a polygonal cross-sectional shape including a triangular or trapezoidal shape. 
         [0022]    The reflector may include a reflection layer disposed along the edge, and a plurality of through holes provided in the reflection layer. 
         [0023]    The through holes may change in size according to positions relative to the light sources. 
         [0024]    The light regulator may include one or more absorbers for absorbing light emitted from the light sources. 
         [0025]    The absorbers may be discontinuously disposed in portions of the edge corresponding to areas between light sources close to the edge. 
         [0026]    The light regulator may include a plurality of reflectors for reflecting light emitted from the light sources to an inside or an upper part of an area defined by the first surface, and one or more absorbers disposed between the reflectors. 
         [0027]    The reflection layer may be disposed on the first surface. 
         [0028]    The light regulator may be formed by bending the reflection layer. 
         [0029]    Meanwhile, the light regulator may be provided at least one side of four edges of the first surface. 
         [0030]    In accordance with another aspect of the present invention, a planar lighting device includes a plurality of light sources mounted on a first surface of a circuit substrate such that the light sources are spaced apart by a predetermined distance, a light regulator discontinuously disposed in at least one portion of an edge of the first surface, the light regulator regulating luminance difference caused by difference in distance between a plurality of light sources close to the edge by reflecting or absorbing light, and an optical sheet disposed on the light sources. 
         [0031]    It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0032]    The accompanying drawings, which are included to provide further understanding of the disclosure and are incorporated in and constitute a part of this application, illustrate embodiments of the disclosure and together with the description serve to explain the principle of the disclosure. In the drawings: 
           [0033]      FIG. 1  is a sectional view illustrating an example of a planar lighting device; 
           [0034]      FIGS. 2 and 3  are schematic views illustrating distribution of luminance at an edge of a reflection surface according to position of light sources; 
           [0035]      FIG. 4  is a schematic perspective view illustrating a first example of a planar lighting device including a light regulator; 
           [0036]      FIG. 5  is a schematic view illustrating traveling of light seen from the cross-section taken along the line A-A of  FIG. 4 ; 
           [0037]      FIG. 6  is a schematic view illustrating traveling of light seen from the cross-section taken along the line B-B of  FIG. 4 ; 
           [0038]      FIG. 7  is a schematic view illustrating an example of luminance regulation by the light regulator; 
           [0039]      FIG. 8  is a schematic perspective view illustrating a second example of a planar lighting device including a light regulator; 
           [0040]      FIG. 9  is a schematic view illustrating traveling of light seen from the cross-section taken along the line C-C of  FIG. 8 ; 
           [0041]      FIG. 10  is a schematic view illustrating traveling of light seen from the cross-section taken along the line D-D of  FIG. 8 ; 
           [0042]      FIG. 11  is a schematic view illustrating an example of luminance regulation by the light regulator; 
           [0043]      FIG. 12  is a schematic perspective view illustrating a third example of a planar lighting device including a light regulator; 
           [0044]      FIG. 13  is a schematic view illustrating traveling of light seen from the cross-section taken along the line E-E of  FIG. 12 ; 
           [0045]      FIG. 14  is a schematic view illustrating traveling of light seen from the cross-section taken along the line F-F of  FIG. 12 ; 
           [0046]      FIG. 15  is a schematic view illustrating an example of luminance regulation by the light regulator; 
           [0047]      FIG. 16  is a schematic perspective view illustrating a fourth example of a planar lighting device including a light regulator; 
           [0048]      FIG. 17  is a schematic view illustrating traveling of light seen from the cross-section taken along the line G-G of  FIG. 16 ; 
           [0049]      FIG. 18  is a schematic view illustrating traveling of light seen from the cross-section taken along the line H-H of  FIG. 16 ; 
           [0050]      FIG. 19  is a schematic view illustrating an example of luminance regulation by the light regulator; 
           [0051]      FIGS. 20 to 23  are sectional views illustrating examples of a reflection plate; 
           [0052]      FIGS. 24 and 25  are sectional views illustrating examples of a reflection structure; and 
           [0053]      FIGS. 26 and 27  are schematic perspective views illustrating examples of configurations of the light regulator. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0054]    Reference will now be made in detail to the specific embodiments of the present invention, examples of which are illustrated in the accompanying drawings. 
         [0055]    However, the present invention allows various modifications and variations and specific embodiments thereof will be exemplified with reference to drawings and be described in detail. The present invention should not be construed as limited to the embodiments set forth herein and includes modifications, variations, equivalents, and substitutions compliant with the spirit or scope of the present invention defined by the appended claims. 
         [0056]    It will be understood that when an element such as a layer, area or substrate is referred to as being “on” another element, it can be directly on the element, or one or more intervening elements may also be present therebetween. 
         [0057]    In addition, it will be understood that although terms such as “first” and “second” may be used herein to describe elements, components, areas, layers and/or regions, the elements, components, areas, layers and/or regions should not be limited by these terms. 
         [0058]      FIG. 1  is a sectional view illustrating an example of a planar lighting device. 
         [0059]    The planar lighting device  20  may be disposed on a lower cover  16  and a liquid crystal panel (not shown) may be disposed on the planar lighting device  20 . 
         [0060]    The planar lighting device  20  includes a plurality of light sources  22  mounted respectively on a plurality of circuit substrates  21  disposed in an upper part of the lower cover  16 . Each light source  22  may be mounted by surface-mounting a light emitting diode (LED) package on the circuit substrate  21 . 
         [0061]    The light source  22  including the light emitting diode (LED) package includes a pair of electrodes  222  passing through a sub-mount substrate  221 , an LED  223  connected to and mounted on the electrode  222 , and a phosphor layer  224  containing a silicone resin mixture disposed outside the LED  223 . 
         [0062]    The phosphor layer  224  may have a planarized upper surface and the phosphor layer  224  may be provided on the upper surface with an optical layer  225  having optical property such as reflectivity or transmittance. 
         [0063]    The optical layer  225  may be formed of a material prepared by mixing a resin with phenyl propanol amine (PPA), epoxy molding compound (EMC), micro-cell polyethylene terephthalate (MCPET), silver (Ag) and aluminum (Al) having reflectivity, and a bead of Ti, Al, Ag, SiO 2  or the like, exhibiting reflectivity, transmittance or refraction. 
         [0064]    Light emitted upward from the LED  223  through the optical layer  225  is reflected in a side direction of the phosphor layer  224 . The LED  223  is a blue LED and the phosphor material constituting the phosphor layer  224  is a yellow phosphor, thus rendering white light to be emitted from the light source  22 . 
         [0065]    The circuit substrate  21  on which the light source  22  is mounted may be disposed on a mount groove  161  disposed on the upper surface of the lower cover  16 . In addition, a plurality of mount grooves  161  including the mount groove  161  may be spaced from one another by a predetermined distance and circuit substrates  21  including the circuit substrate  21  disposed respectively in the mount grooves  161  may be also spaced from one another by a predetermined distance. Accordingly, the light sources  22  may be spaced from one another by a predetermined distance on the lower cover  16 . 
         [0066]    The light sources  22  may be disposed in one line or a zigzag form. 
         [0067]    A reflection layer  23  may be disposed in a gap between the light sources  22  disposed on the circuit substrates  21 . Accordingly, the light sources  22  protrude from an upper surface of the reflection layer  23 . 
         [0068]    In addition, a transmission regulation layer  15  having a pattern of holes  151  transmitting light, which is spaced from the reflection layer  23  by a predetermined distance, may be disposed on the reflection layer  23 . 
         [0069]    The transmission regulation layer  15  may utilize a reflective sheet which transmits some of light emitted from the light source  22  and reflects the remaining light again. 
         [0070]    The transmission regulation layer  15  is a hole patterned reflective sheet having a plurality of holes  151  on an upper surface thereof. That is, light discharged from the light source  22  through the holes  151  or reflected by the reflection layer  23  passes through the holes  151 , and light travelling in other regions is reflected to the reflection layer  23  again or is refracted or reflected by a spacer  30 . 
         [0071]    In addition, radiuses of the holes  151  increase with increasing distance from a center of the light source  22 , thus passing more light than is reflected with increasing distance from the light source  22 . 
         [0072]    That is, the holes  151  are disposed such that the size of the holes  151  is the smallest in the closest position to the light source  22  and is the largest in the middle between two adjacent light sources  22 . 
         [0073]    In addition, the holes  151  are disposed such that sizes of the holes  151  gradually increase from the closest position to the light source  22  to the middle position between two adjacent light sources  22  and decrease from the middle position between the two adjacent light sources  22  to the closest position to the light source  22 . 
         [0074]    The reason for this is that intensity of light increases as the light source becomes closer to the light source  22  and decreases as the light source becomes farther from the light source  22 . Preferably, light transmission increases as a distance from the light source  22  increases and decreases as the distance from the light source  22  decreases so that luminance of light is uniformly maintained throughout the entire surface of a display using such a planar lighting device. 
         [0075]    Light emitted from the light source  22  is diffused in a side direction through the gap between the reflection layer  23  and the transmission regulation layer  15 . The diffused light is emitted in an upper direction through the pattern of the holes  151 . As such, the area between the reflection layer  23  and the transmission regulation layer  15  is defined by a light-guide layer  24 . 
         [0076]    The light-guide layer  24  may be formed by a spacer  25  enabling a predetermined gap between the reflection layer  23  and the transmission regulation layer  15  to be maintained. 
         [0077]    That is, the spacer  25  functions to maintain the distance between the transmission regulation layer  15  and the light source  22  and extends to a height corresponding to a designed height of the light-guide layer  24  and a length corresponding to a length of the reflection layer  23 . 
         [0078]    The spacer  25  is formed of a material such as polycarbonate (PC), polymethyl methacrylate (PMMA), glass, a resin, phenyl propanol amine (PPA) or aluminum (Al) and thus exhibits light transmission, refraction or reflection. 
         [0079]    In addition, the spacer  25  may be mounted by applying an adhesive to the upper and lower surfaces of the spacer  25  and performing UV curing or thermal curing. 
         [0080]    In addition, optical sheets such as a diffusion layer  11 , a lower polarizing plate  12 , a color filter substrate  13  and an upper polarizing plate  14  may be disposed on the transmission regulation layer  15 . 
         [0081]    Meanwhile, the circuit substrate  21  may be fixed to the mount groove  161  of the lower cover  16  by applying an adhesive  17  to a lower surface of the circuit substrate  21  and a lower surface of the reflection layer  23 . In addition, the reflection layer  23  may be fixed to the circuit substrate  21 . 
         [0082]      FIGS. 2 and 3  are schematic views illustrating distribution of luminance at an edge of a reflection surface according to position of light sources. 
         [0083]    As described above, in a direct-type planar lighting device, a combination of light emitted from the light sources  22  is emitted in the center of the surface on which the light sources  22  are distributed. Accordingly, luminance of the planar lighting device can be uniformized using the optical sheets  11 ,  12 ,  13  and  14  described above. 
         [0084]    The surface on which the light sources  22  are distributed may be a surface of the circuit substrate  21  or an upper surface of the reflection layer  23  disposed on the circuit substrate  21 . Hereinafter, the following description is provided under the assumption that the surface on which the light sources  22  are distributed is the upper surface (reflection surface) of the reflection layer  23 . 
         [0085]    Meanwhile, difference in luminance between areas close to the light source  22  and areas far from the light source  22  may be generated at an edge  26  in which distribution of the light source  22  is completed. 
         [0086]    For example, as can be seen from  FIGS. 2 and 3 , as the disposition of the light source  22  is changed, luminance difference may be generated according to the distance from the light source  22  at the edge  26  of the light source  22 . 
         [0087]    That is, in a direct-type lighting device, luminance is high at the position close to the light source  22  and luminance is low at the position far from the light source  22  at an edge  26  of the upper surface of the reflection layer  23 . 
         [0088]    Accordingly, as shown in  FIG. 4 , preferably, a light regulator  300  for regulating luminance difference caused by distance difference between the light source  22  and the edge  26  may be provided. 
         [0089]    The light regulator  300  regulates luminance difference which may occur between the reflection layer  23  and the edge  26 . That is, uniformity of luminance can be improved at the edge  26 . 
         [0090]    Accordingly, when such a light regulator  300  is provided, light emitted from the light sources  22  may be more uniform. More preferably, more uniform lighting can be implemented with the transmission regulation layer  15  having the pattern of holes  151  and the optical sheets  11 ,  12 ,  13  and  14  disposed on the reflection layer  23  and the light source  22 . 
         [0091]    As an example, the light regulator  300  may include a plurality of reflectors  30  for reflecting light emitted from the light sources  22  to an inside of an area formed by the reflection layer  23 , disposed at the edge  26  of the reflection layer  23 . 
         [0092]    For example, the reflectors  30  are disposed in portions of the edge  26  farther from the light sources  22  so that the reflectors  30  reflect light travelling toward the edge  26  and thus focus surrounding light upon relatively dark regions, thereby regulating luminance uniformity. 
         [0093]    As shown in  FIG. 4 , the reflectors  30  may be discontinuously disposed at the edge  26  in the positions relatively far from the light sources  22 . That is, the reflectors  30  with a predetermined width may be discontinuously disposed along the edge  26  in the positions farther from the light sources  22 . 
         [0094]    In addition, from another point of view, the reflectors  30  may be discontinuously disposed in portions of the edge corresponding to areas between adjacent light sources  22  close to the edge  26 . That is, the reflectors  30  with a predetermined width may be disposed in portions of the edge corresponding to areas between two light sources  22  close to the edge  26 . 
         [0095]      FIG. 5  shows traveling of light seen from the cross-section taken along the line A-A of  FIG. 4 , and  FIG. 6  shows traveling of light seen from the cross-section taken along the line B-B of  FIG. 4 . In addition,  FIG. 7  is a schematic view illustrating an example of luminance regulation by the reflector  30 . 
         [0096]    As shown in  FIG. 5 , the reflector  30  is disposed in a portion of the edge  26  in the position farther from the light source  22  so that light emitted from the light source  22  is reflected through the reflector  30  and brightness of area which may be dark due to great distance from the light source  22  are thus reinforced. 
         [0097]    In a portion of the edge  26  in the position closer to the light source  22 , light travels without being reflected in the portion of the edge  26  to prevent the area from becoming brighter and thereby regulate luminance, as shown in  FIG. 6 . 
         [0098]    In addition, as shown in  FIG. 7 , light emitted from the light source  22  close to the edge  26  is also reflected by the reflector  30  and travels toward areas farther from the light source  22 . Accordingly, such a reflector  30  uniformizes luminance of the light sources  22  close to the edge  26  and of the light sources  22  far from the edge  26 . 
         [0099]    As shown in  FIG. 8 , as another example, the light regulator  300  includes a plurality of absorbers  31  for absorbing light emitted from the light source  22 . The absorbers  31  may be disposed at the edge  26  in positions corresponding to the light sources  22  close to the edge  26 . 
         [0100]    Such an absorber  31  is close to the light source  22  and absorbs light of areas brighter than neighboring areas to darken the brighter areas and thereby regulate luminance uniformity. 
         [0101]    As shown in  FIG. 8 , the absorbers  31  may be discontinuously disposed close to the light sources  22  at the edge  26 . That is, the absorbers  31  with a predetermined width may be discontinuously disposed along the edge  26  in positions relatively close to the light sources  22 . 
         [0102]      FIG. 9  shows traveling of light seen from the cross-section taken along the line C-C of  FIG. 8 , and  FIG. 10  shows traveling of light seen from the cross-section taken along the line D-D of  FIG. 8 . In addition,  FIG. 11  is a schematic view illustrating an example of luminance regulation by the absorber  31 . 
         [0103]    As shown in  FIG. 9 , in a portion of the edge  26  in the position farther from the light source  22 , light travels without being reflected in the portion of the edge  26 , thereby regulating luminance. 
         [0104]    As shown in  FIG. 10 , the absorber  31  is disposed along the edge in the position of the edge  26  close to the light source  22  so that light emitted from the light source  22  is absorbed in the absorber  31  without being reflected or passing through the absorber and brightness of areas which may be relatively bright due to small distance from the light source  22  are thus reduced. 
         [0105]    In addition, as shown in  FIG. 11 , as described above, light emitted from the light source  22  close to the edge  26  is absorbed in the absorber  31  and light emitted from the light source  22  far from the edge  26  passes through the absorber  31  without being absorbing therein. Accordingly, the absorber  31  contributes to luminance uniformity of the light sources  22  close to the edge  26  and of the light sources  22  far from the edge  26 . 
         [0106]    As shown in  FIG. 12 , the light regulator  300  includes a plurality of reflectors  30  and a plurality of absorbers  31  which are alternately disposed, as another example of the light regulator  300 . 
         [0107]    That is, the light regulator  300  may include the reflectors  30  for reflecting light emitted from the light sources  22  to an inside of the reflection layer  23  and absorbers  31  being disposed between the reflectors  30  and absorbing light emitted from the light sources  22 . 
         [0108]    As such, the reflectors  30  and the absorbers  31  alternate with each other and the light regulator  300  may be continuously disposed along an edge  26  of at least one side of the reflection layer  23 . 
         [0109]    Although  FIG. 12  illustrates an example in which the reflectors  30  and the absorbers  31  are provided in edges of upper and lower sides of a transmission regulation layer  23  for convenience, the reflectors  30  and the absorbers  31  may be provided in edges of left and right sides thereof. 
         [0110]    As shown in the drawing, the reflectors  30  having a predetermined width may be disposed along the edge  26  in positions of portions of the edge  26  far from the light sources  22  and the absorbers  31  having a predetermined width may be disposed along the edge  26  in positions of portions of the edge  26  close to the light source  22 . 
         [0111]    Each reflector  30  and each absorber  31  may have the same width. However, in some cases, the width of the reflector  30  may be greater than that of the absorber  31  and vice versa. 
         [0112]      FIG. 13  shows traveling of light seen from the cross-section taken along the line E-E of  FIG. 12 , and  FIG. 14  shows traveling of light seen from the cross-section taken along the line F-F of  FIG. 12 . In addition,  FIG. 15  is a schematic view illustrating an example of luminance regulation by the reflector  30  and the absorber  31 . 
         [0113]    As shown in  FIG. 13 , the reflector  30  is disposed along the edge in the position of a portion of the edge  26  far from the light source  22  so that light emitted from the light source  22  is reflected by the reflector  30  and brightness of areas which may be relatively dark due to great distance from the light source  22  is thus reinforced. 
         [0114]    The absorber  31  is disposed in a portion of the edge  26  close to the light source  22 , as shown in  FIG. 14 , so that light emitted from the close light source  22  is absorbed in the absorber  31  and luminance of areas which may be relatively bright is thus regulated. 
         [0115]    In addition, as shown in  FIG. 15 , light emitted from the light source  22  close to the edge  26  may be absorbed in the absorber  31  and light emitted from the light source  22  far from the edge  26  is reflected by the reflector  30 . Light emitted from the light source  22  close to the edge  26  is reflected by the reflector  30  and luminance of areas which may be relatively dark is thus regulated. 
         [0116]    That is, the reflector  30  and the absorber  31  regulate light emitted from the light sources  22  close to the edge  26  and light emitted from the light sources  22  far from the edge  26 , thus contributing to luminance uniformity. 
         [0117]    As shown in  FIG. 16 , as another example of the light regulator  300 , the light regulator  300  includes a reflection layer  32  disposed along the edge  26  and a plurality of through holes  33  provided in the reflection layer  32 . 
         [0118]    Although  FIG. 16  illustrates an example in which the reflection layer  32  and the through holes  33  are provided in edges of upper and lower sides of the transmission regulation layer  23  for convenience, the reflection layer  32  and the through holes  33  may be provided in edges of left and right sides thereof. 
         [0119]    As shown in  FIG. 16 , the through holes  33  may change in size according to position relative to the light source  22 . 
         [0120]    That is, larger through holes  33  are disposed in areas closer to the light source  22  and small through holes are disposed in areas far from the light source  22 . 
         [0121]    In addition, the size of the through holes  33  may be gradually changed. That is, the largest through hole  33  is disposed in an area relatively close to the light source  22 , through holes  33  gradually decrease in size, with increasing the distance from the largest through hole and the smallest through hole  33  is disposed in the position farthest from the light source  22 . 
         [0122]      FIG. 17  shows traveling of light seen from the cross-section taken along the line G-G of  FIG. 16 , and  FIG. 18  shows traveling of light seen from the cross-section taken along the line H-H of  FIG. 16 . In addition,  FIG. 19  is a schematic view illustrating an example of luminance regulation by the reflection layer  32 . 
         [0123]    As shown in  FIG. 17 , the reflection layer  32  having small through holes  33  is disposed in a portion of the edge  26  relatively far from the light source  22  so that a small amount of light emitted from the light source  22  passes through the through holes  33 , most thereof is reflected, and brightness of an area which may be relatively dark due to great distance from the light source  22  is thus reinforced. 
         [0124]    In addition, a reflection layer  32  having large through holes  33  is disposed in a portion of the edge  26  close to the light source  22 , as shown in  FIG. 18 , so that a great amount of light emitted from the light source  22  passes through the through holes  33  and brightness of an area which may be relatively bright is thus regulated. 
         [0125]      FIG. 19  is a schematic view illustrating travelling of light by the reflection layer  32  having through holes  33  with various sizes. 
         [0126]    That is, some of light emitted from the light source  22  close to the edge  26  passes through large through holes  33  and the remaining thereof is reflected by a portion of the reflection layer  32  in which small through holes  33  are disposed, thereby regulating luminance of areas which may be relatively dark. 
         [0127]    In addition, as most of light emitted from light source  22  far from the edge  26  is reflected by the reflection layer  32 , luminance of areas, which may be relatively dark, is regulated and luminance uniformity can be thus improved. 
         [0128]    Meanwhile, the reflector  30  or the reflection layer  32  described above is shown as a form such as thin wall, but may be provided with a reflection plate  34  whose cross-section has an inclined surface having a polygonal shape, as shown in  FIG. 20 . 
         [0129]    That is, as shown in  FIG. 20 , a reflection plate  34  whose cross-section has an inclined surface having a right-angled triangle shape is formed so that light emitted from the light source  22  travels upward. 
         [0130]    In addition, regarding the shape for reflection, a reflection plate  35  whose cross-section has a curved surface having a semi-spherical or circular arc shape may be formed, as shown in  FIG. 21 . In some cases, the reflection plate  35  may have an oval curved surface. 
         [0131]    That is, a reflection plate  36  whose cross-section has an inclined surface having a triangle shape is formed, as shown in  FIG. 22 , and a reflection plate  37  whose cross-section has an inclined surface having a trapezoidal shape is formed, as shown in  FIG. 23 . 
         [0132]    The reflection plate  37  reflects at least part of light emitted from the light source  22  toward the upper surface of the reflection layer  23  and reflects the remaining light into an inside of an area formed by the reflection layer  23 . 
         [0133]    The reflection plates  34 ,  35 ,  36  and  37  having various shapes may be applied to the shape of the reflector  30  or the reflection layer  32  described above. 
         [0134]    Meanwhile, the absorption layer  31  described above may be also formed as one of shapes that are the same as the reflection plates  34 ,  35 ,  36  and  37 . 
         [0135]    As shown in  FIG. 24 , in a portion of the edge  26  in the position far from the light source  22 , a reflection structure  38  for reducing the distance between the edge and the light source  22  may be provided. 
         [0136]    That is, in the portion of the edge  26  far from the light source  22 , the distance between the edge and the light source  22  is reduced using the reflection structure  38  and surrounding light is transferred to dark areas and luminance uniformity can thus be regulated. 
         [0137]    The reflection structure  38  may be formed of a highly reflective material.  FIG. 24  shows the reflection structure  38  having an oval portion, but the shape of the reflection structure  38  may be selected from a variety of shapes such as curved shapes including circular or circular arc shapes, and triangular or trapezoidal shapes. 
         [0138]    Regarding the light regulator  300  including the reflector  30 , the absorber  31  and the reflection plate  32  described above, another light regulator  300  newly produced is bonded to the edge  26  of the light regulator  300 , as shown in  FIG. 26 . 
         [0139]    For example, as shown in  FIG. 26 , reflectors  30  and absorbers  31  which alternate with each other are produced as separate structures and are then bonded to the edge  26 . 
         [0140]    In addition, as shown in  FIG. 27 , a surface of the reflection layer  23  may be bent in an inside direction to constitute the reflector  30 . 
         [0141]    That is, the reflection layer  23  is produced such that it has a portion serving as the reflector  30  and the portion is bent to constitute the reflector  30 . 
         [0142]    It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.