Patent Publication Number: US-2011051037-A1

Title: Optical assembly, backlight unit, and display device

Description:
This application claims the priority benefit of Korean Patent Application Nos. 10-2009-0079710 filed on Aug. 27, 2009, 10-2009-0079700 filed on Aug. 27, 2009, 10-2009-0080249 filed on Aug. 28, 2009, 10-2009-0114226 filed on Nov. 24, 2009, 10-2009-0114227 filed on Nov. 24, 2009, 10-2009-0114225 filed on Nov. 24, 2009, and 10-2010-0004454 filed on Jan. 18, 2010, U.S. Provisional Application Nos. 61/320,725 filed on Apr. 5, 2010, and 61/237,587 filed on Aug. 27, 2009, which is incorporated herein by reference for all purposes as if fully set forth herein. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Exemplary embodiments of the invention relate to an optical assembly, a backlight unit including the optical assembly, and a display device including the backlight unit. 
     2. Description of the Related Art 
     Liquid crystal displays have been widely used in various fields including the notebook PC market and the monitor market because of excellent characteristics such as thin profile, lightness in weight, and low power consumption. 
     The liquid crystal display includes a liquid crystal display panel and a backlight unit providing light to the liquid crystal display panel. The liquid crystal display panel transmits light provided by the backlight unit and adjusts a transmittance of the light, thereby displaying an image. 
     The backlight unit may be classified into an edge type backlight unit and a direct type backlight unit depending on a location of light sources. In the edge type backlight unit, light sources are disposed at the side of the liquid crystal display panel, and a light guide plate is disposed on a back surface of the liquid crystal display panel and guides the light emitted from the side of the liquid crystal display panel to the back surface of the liquid crystal display panel. In the direct type backlight unit, light sources are disposed on a back surface of the liquid crystal display panel, and the light emitted from the light sources may be directly provided to the back surface of the liquid crystal display panel. 
     Examples of the light sources may include an electroluminescence (EL) device, a cold cathode fluorescent lamp (CCFL), a hot cathode fluorescent lamp (HCFL), and a light emitting diode (LED). The LED has low power consumption and high light emitting efficiency. 
     SUMMARY OF THE INVENTION 
     Exemplary embodiments of the invention provide an optical assembly, a backlight unit including the optical assembly, and a display device including the backlight unit. 
     Embodiments of the invention provide a light generating device including one or more light source devices each including a light emitting unit such as an LED, which can be used in a backlight unit or other device and which address the limitations and disadvantages associated with the background art. 
     According to an embodiment, the invention provides a light generating device comprising: a first layer; a plurality of light source devices disposed on the first layer and configured to emit light from side surfaces of the light source devices, at least one of the light source devices having a light emitting diode and at least one lead electrode electrically connected to the light emitting diode, each of the at least one lead electrode being disposed in at least one lead electrode area of the corresponding light source device; a reflection layer configured to reflect the light emitted from the light source devices, the reflection layer disposed on the first layer and defining at least one predetermined gap between the at least one lead electrode area of the corresponding light source device and the reflection layer; and a second layer covering the light source devices and the reflection layer. 
     According to an embodiment, the invention provides a backlight device comprising: a plurality of first arrays of light source devices and a plurality of second arrays of light source devices disposed on a first layer, the first and second arrays of light source devices configured to emit light in at least two different directions, at least one of the light source devices including a light emitting diode; a reflection layer configured to reflect the light emitted from the first and second arrays of light source devices, the reflection layer disposed on the first layer and surrounding the first and second arrays of light source devices with a plurality of predefined gaps, each of the predefined gaps provided between the reflection layer and at least one of the light source devices; and a second layer covering the reflection layer and the first and second arrays of light source devices. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. In the drawings: 
         FIGS. 1 and 2  illustrate a display device according to an exemplary embodiment of the invention: 
         FIG. 3  illustrates a display module according to an exemplary embodiment of the invention: 
         FIGS. 4 and 5  illustrate a first exemplary configuration of a backlight unit according to an exemplary embodiment of the invention; 
         FIG. 6  illustrates a second exemplary configuration of a backlight unit according to an exemplary embodiment of the invention; 
         FIG. 7  illustrates a third exemplary configuration of a backlight unit according to an exemplary embodiment of the invention; 
         FIGS. 8 to 13  illustrate a fourth exemplary configuration of a backlight unit according to an exemplary embodiment of the invention; 
         FIGS. 14 to 17  illustrate a location of a first pattern of a backlight unit according to an exemplary embodiment of the invention; 
         FIGS. 18 to 21  illustrate a shape of a first pattern according to an exemplary embodiment of the invention; 
         FIGS. 22 and 23  illustrate a fifth exemplary configuration of a backlight unit according to an exemplary embodiment of the invention; 
         FIG. 24  illustrates a sixth exemplary configuration of a backlight unit according to an exemplary embodiment of the invention: 
         FIGS. 25 and 26  are cross-sectional views for illustrating a location relationship between a light source and a reflection layer of a backlight unit; 
         FIGS. 27 and 28  illustrate a structure of a light source of a backlight unit according to an embodiment of the invention; 
         FIG. 29  illustrates a structure of light sources of a backlight unit according to an embodiment of the invention; 
         FIGS. 30 to 34  illustrate a front shape of a backlight unit according to an exemplary embodiment of the invention; 
         FIGS. 35 to 41  illustrate a structure of a reflection layer of a backlight unit according to an exemplary embodiment of the invention; 
         FIGS. 42 and 43  illustrate a seventh exemplary configuration of a backlight unit according to an exemplary embodiment of the invention; 
         FIGS. 44 to 47  illustrate a structure of a reflection layer of the backlight unit according to the seventh exemplary configuration; 
         FIGS. 48 to 55  are enlarged diagrams of various examples of an area R shown in  FIG. 43  according to an embodiment of the invention; 
         FIGS. 56A and 56B  are top and side views of a light source device according to an embodiment of the invention; 
         FIG. 57  illustrates an eighth exemplary configuration of a backlight unit according to an exemplary embodiment of the invention; and 
         FIG. 58  is a cross-sectional view illustrating a configuration of a display device according to an exemplary embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Reference will now be made in detail embodiments of the invention examples of which are illustrated in the accompanying drawings. In this regard, each of all display devices, backlight units, light source devices, and any device that includes such backlight unit or light source device discussed below is operatively coupled and configured. Further, a backlight unit according to embodiments of the invention preferably is fixed to a back of a display panel and has a same or similar size as the display panel to correspond to the entire display region of the display panel. Furthermore, such a backlight unit preferably includes a plurality of light sources which are disposed in arrays, lines, patterns, etc. throughout the entire area of the backlight unit that corresponds to the entire display region of the display panel. As such, the light sources are not just located at one side of the display panel, but are preferably dispersed below throughout the entire display region of the display panel. In these figures, arrows indicate a general light emitting direction of the light source, e.g., a general direction in which the light from a light emitting surface of the light source is emitted, but the light from the light source may emit not necessarily in a single line but through an area in the indicated direction. 
     According to various embodiments of the invention, any one or more features from one embodiment/example/variation of the invention can be applied to (e.g. added, substituted, modified, etc.) any one or more other embodiments/examples/variations discussed below according to the invention. Further any operations/methods discussed below can be implemented in any of these devices/units or other suitable devices/units. 
       FIGS. 1 and 2  illustrate a display device according to an exemplary embodiment of the invention. 
     As shown in  FIG. 1 , a display device  1  according to an exemplary embodiment of the invention includes a display module  20 , a front cover  30  covering the display module  20 , a driver  55  included in the display module  20 , and a back cover  40  covering the driver  55 . 
     The front cover  30  may include a front panel formed of a transparent material capable of transmitting light. The front panel is separated from the display module  20  by a predetermined distance and protects the display module  20 . The front panel transmits light emitted by the display module  20 , so that a user can see an image displayed on the display module  20 . 
     The front cover  30  may be made using a flat plate not having a window  30   a . In this case, the front cover  30  is formed of a transparent material capable of transmitting light, for example, injection-molded plastic. As above, if the front cover  30  is made of the flat plate, a frame may be omitted from the front cover  30 : 
     The driver  55  may include a driving controller  55   a , a main board  55   b , and a power supply unit  55   c . The driving controller  55   a  may be a timing controller and controls operation timing of each of driver integrated circuits (ICs) of the display module  20 . The main board  55   h  transfers a vertical synchronous signal, a horizontal synchronous signal, and a RGB resolution signal to the driving controller  55   a . The power supply unit  55   c  applies power to the display module  20 . 
     The driver  55  is included in the display module  20  and may be covered by the back cover  40 . The display device  1  may further include a stand  60  for supporting the display device  1 . 
     On the other hand, as shown in  FIG. 2 , the driving controller  55   a  of the driver  55  is included in the display module  20 , and the main board  55   b  and the power supply board  55   c  corresponding to the power supply unit  55   c  may be included in the stand  60 . The back cover  40  may cover only the driving controller  55   a  of the driver  55 . 
     In the embodiment of the invention, the main board  55   b  and the power supply board  55   c  are separately configured. However, the main board  55   b  and the power supply board  55   c  may be configured on one integrated board. Other configurations may be used for the main hoard  55   b  and the power supply board  55   c.    
       FIG. 3  illustrates an example of the display module  20 . As shown in  FIG. 3 , the display module  20  includes a display panel  100  and a backlight unit  200 . 
     The display panel  100  includes a color filter substrate  110  and a thin film transistor (TFT) substrate  120  that are positioned opposite each other and are attached to each other with a uniform cell gap therebetween. A liquid crystal layer is interposed between the two substrates  110  and  120 . 
     The color filter substrate  110  includes a plurality of color filters each including red (R), green (G), and blue (B) color filters and may generate a red, green, or blue image when light is applied to the display device  1 . In the embodiment of the invention, each of the color filters can include the red, green, and blue sub-color filters. Other structures may be used for a color filter corresponding to a pixel. For example, each pixel may include red, green, blue, and white (W) sub-pixels. 
     The TFT substrate  120  is a substrate, on which a plurality of switching elements are formed, and may switch on and off selectively a plurality of corresponding pixel electrodes. For example, a common electrode and the pixel electrode may change an arrangement of liquid crystal molecules of the liquid crystal layer depending on a predetermined voltage supplied thereto. 
     The liquid crystal layer is comprised of the liquid crystal molecules. The arrangement of the liquid crystal molecules varies depending on a voltage difference between the pixel electrode and the common electrode. Hence, light provided by the backlight unit  200  may be incident on the color filter substrate  110  based on changes in the arrangement of the liquid crystal molecules of the liquid crystal layer. 
     An upper polarizing plate  130  and a lower polarizing plate  140  may be respectively positioned on and under the display panel  100 . More particularly, the upper polarizing plate  130  may be positioned on the color filter substrate  110 , and the lower polarizing plate  140  may be positioned under the TFT substrate  120 . 
     A gate driver and a data driver, each of which generates driving signals for driving the gate lines and data lines of the display panel  100 , may be provided on the side of the display panel  100 . 
     As shown in  FIG. 3 , the display module  20  according to the embodiment of the invention may be configured so that the backlight unit  200  adheres closely to the display panel  100 . For example, the backlight unit  200  may be attached and fixed to the bottom of the display panel  100 , more particularly, the lower polarizing plate  140 . For this, an adhesive layer may be formed between the lower polarizing plate  140  and the backlight unit  200 . 
     As described above, the entire thickness of the display device  1  may be reduced by attaching the backlight unit  200  close to the display panel  100 , and thus an external appearance of the display device  1  may be improved. Further, because a separate structure for fixing the backlight unit  200  is removed, the structure and the manufacturing process of the display device  1  may be simplified. 
     Further, because a space between the backlight unit  200  and the display panel  100  is removed, foreign substances may be prevented from penetrating into the space. Hence, a malfunction of the display device  1  or a reduction in the image quality of an image displayed on the display device  1  resulting from the foreign substances may be prevented. 
     The backlight unit  200  according to the embodiment of the invention may have the structure in which a plurality of function layers are sequentially laminated, and at least one layer of the plurality of function layers may include a plurality of light sources. 
     Each of the plurality of function layers constituting the backlight unit  200  may be formed of a flexible material, so that the backlight unit  200  is closely attached and fixed to bottom of the display panel  100 . 
     The display panel  100  according to the embodiment of the invention may be divided into a plurality of regions. A brightness of light emitted from a region of the backlight unit  200  corresponding to each of the divided regions (i.e., a brightness of the corresponding light source) is adjusted based on a gray peak value or a color coordinate signal of each divided region. Hence, a luminance of the display panel  100  may be adjusted. For this, the backlight unit  200  may operate, so that regions of the backlight unit  200  respectively corresponding to the divided regions of the display panel  100  are dividedly driven. 
       FIG. 4  illustrates a first exemplary configuration of the backlight unit  200  according to the exemplary embodiment of the invention. As shown in  FIG. 4 , the backlight unit  200  according to the first exemplary configuration may include a first layer  210 , a plurality of light sources  220 , a second layer  230 , and a reflection layer  240 . As mentioned above, the backlight unit  200  in this or other embodiments may have a same or similar size as the display panel  100  so that it covers the entire display area of the display panel  100 . Thus the light sources  220  in this or other embodiments are provided throughout the entire area of the backlight unit  200  so that these light sources  220  are dispersed below the entire display area of the display panel  100 . 
     The plurality of light sources  220  may be formed on the first layer  210 , and the second layer  230  may be formed on the first layer  210  so as to cover the light sources  220 . For instance, the second layer  230  encapsulates (covers entirely) the light sources  220  on the first layer  210 . 
     The first layer  210  may be a substrate on which the plurality of light sources  220  are mounted. An electrode pattern for connecting the light sources  220  to an adapter for a power supply may be formed on the first layer  210 . For example, a carbon nanotube electrode pattern for connecting the light sources  220  to the adapter may be formed on the first layer  210 . 
     The first layer  210  may be formed of polyethylene terephthalate (PET), glass, polycarbonate (PC), or silicon. The first layer  210  may be a printed circuit board (PCB) substrate, on which the plurality of light sources  220  are mounted, and may be formed in a film form. 
     The light source  220  may be one of a light emitting diode (LED) chip and a light emitting diode package having at least one light emitting diode chip. In the embodiment of the invention, the light emitting diode package is described as an example of the light source  220 . 
     The LED package constituting the light source  220  may be classified into a top view type LED package and a side view type LED package based on a facing direction of a light emitting surface of the LED package. In the embodiment of the invention, the light source  220  may be configured using at least one of the top view type LED package, in which the light emitting surface is upward formed, and the side view type LED package in which the light emitting surface is formed toward the side. 
     If the side view type LED package is used as the light source  220  in the embodiment of the invention, each of the light sources  220  may have a light emitting surface at the side thereof and may emit light in a lateral direction, i.e., in an extension direction of the first layer  210  or the reflection layer  240 . Thus, a thin profile of the backlight unit  200  may be achieved by reducing a thickness “a” of the second layer  230  formed on the light sources  220 . As a result, a thin profile of the display device  1  may be achieved. 
     The light source  220  may be configured by a colored LED emitting at least one of red light, green light, blue light, etc. or a white LED emitting white light. In addition, the colored LED may include at least one of a red LED, a blue LED, and a green LED. The disposition and emitting light of the light emitting diode may be variously changed within a technical scope of the embodiment. 
     The second layer  230  transmits light emitted by the light sources  220 , and at the same time diffuses the light emitted by the light sources  220 , thereby allowing the light sources  220  to uniformly provide the light to the display panel  100 . 
     The reflection layer  240  is positioned on the first layer  210  and reflects light emitted by the light sources  220 . The reflection layer  240  may be formed in an area excluding a formation area of the light sources  220  from the first layer  210 . The reflection layer  240  reflects light emitted from the light sources  220  and again reflects light totally reflected from a boundary of the second layer  230 , thereby more widely diffusing the light. 
     The reflection layer  240  may contain at least one of metal and metal oxide that are a reflection material. For example, the reflection layer  240  may contain metal or metal oxide having a high reflectance, such as aluminum (Al), silver (Ag), gold (Au), and titanium dioxide (TiO 2 ). In this case, the reflection layer  240  may be formed by depositing or coating the metal or the metal oxide on the first layer  210  or by printing a metal ink on the first layer  210 . The deposition method may use a heat deposition method, an evaporation method, or a vacuum deposition method such as a sputtering method. The coating method or the printing method may use a gravure coating method or a silk screen method. 
     The second layer  230  on the first layer  210  may be formed of a material capable of transmitting light, for example, silicon or acrylic resin. Other materials may be used for the second layer  230 . For example, various types of resin may be used. Further, the second layer  230  may be formed of a resin having a refractive index of approximately 1.4 to 1.6, so that the backlight unit  200  has a uniform luminance by diffusing the light emitted from the light sources  220 . For example, the second layer  230  may be formed of any one material selected from the group consisting of polyethylene terephthalate (PET), polycarbonate (PC), polypropylene, polyethylene, polystyrene, polyepoxy, silicon, acryl, etc. 
     The second layer  230  may contain a polymer resin having an adhesion so as to tightly and closely adhere to the light sources  220  and the reflection layer  240 . For example, the second layer  230  may contain an acrylic resin such as unsaturated polyester, methylmethacrylate, ethylmethacrylate, isobutylmethacrylate, normal butylmethacrylate, normal butyl methylmethacrylate, acrylic acid, methacrylic acid, hydroxy ethylmethacrylate, hydroxy propylmethacrylate, hydroxy ethylacrylate, acrylamide, methylol acrylamide, glycidyl methacrylate, ethylacrylate, isobutylacrylate, normal butylacrylate, 2-ethylhexyl acrylate polymer, copolymer, or terpolymer, etc., an urethane resin, an epoxy resin, a melamine resin, etc. 
     The second layer  230  may be formed by applying and curing a liquid or gel-type resin on the first layer  210  on which the light sources  220  and the reflection layer  240  are formed. Alternatively, the second layer  230  may be formed by applying and partially curing a resin on a support sheet and then attaching the resin to the first layer  210 . 
     As the thickness “a” of the second layer  230  increases, light emitted from the light sources  220  may be more widely diffused. Hence, the backlight unit  200  may provide light having the uniform luminance to the display panel  100 . On the other hand, as the thickness “a” of the second layer  230  increases, an amount of light absorbed in the second layer  230  may increase. Hence, the luminance of light which the backlight unit  200  provides to the display panel  100  may entirely decrease. 
     Accordingly, the thickness “a” of the second layer  230  may be approximately 0.1 mm to 4.5 mm, so that the backlight unit  200  can provide light having the uniform luminance to the display panel  100  without an excessive reduction in the luminance. 
       FIG. 5  illustrates a cross-sectional shape of an area excluding an area of the light sources  220  from the entire area of the backlight unit  200 . More specifically,  FIG. 4  is a cross-sectional view taking a formation area of the light sources  220  in the backlight unit  200  along line A-A′ of  FIG. 30 .  FIG. 5  is a cross-sectional view taking the non-formation area of the light sources  220  in the backlight unit  200  along line B-B′ of  FIG. 30 . The formation area of the light sources  220  is an area where the light sources  220  are formed, and a non-formation area of the light sources  220  is an area where the light sources are not formed. 
     As shown in  FIG. 5 , the backlight unit  200  may have the structure in which the reflection layer  240  covers an upper surface of the first layer  210  in the non-formation area of the light sources  220 . For example, the reflection layer  240  may be formed on the first layer  210  and may have a plurality of holes, into which the light sources  220  may be inserted, at a location corresponding to a formation location of the light sources  220 . The light sources  220  may upwardly protrude from the holes of the reflection layer  240  and may be covered by the second layer  230 . 
       FIG. 6  illustrates a second exemplary configuration of a backlight unit according to the embodiment of the invention. As mentioned above, the backlight unit of  FIG. 6  or any other figures herein can be the backlight unit  200  of  FIG. 3 , a backlight unit used in any display device, or a backlight unit for any device, that needs the backlight unit, and can also be a light generating device. Structures and components identical or equivalent to those described in the first exemplary configuration of the backlight unit may be designated with the same reference numerals in the second exemplary configuration, and a further description may be briefly made or may be entirely omitted. 
     As shown in  FIG. 6 , the plurality of light sources  220  may be mounted on the first layer  210 , and the second layer  230  may be disposed on the first layer  210 . The reflection layer  240  may be formed between the first layer  210  and the second layer  230 , more particularly, on an upper surface of the first layer  210 . 
     The second layer  230  may include a plurality of scattering particles  231 . The scattering particles  231  may scatter or refract incident light, thereby more widely diffusing light emitted from the light sources  220 . 
     The scattering particles  231  may be formed of a material having a refractive index different from a formation material of the second layer  230  so as to scatter or refract the light emitted from the light source  220 . More particularly, the scattering particles  231  may be formed of a material having a refractive index greater than silicon-based resin or acrylic resin forming the second layer  230 . For example, the scattering particles  231  may be formed of polymethylmethacrylate (PMMA)/styrene copolymer (MS), polymethylmethacrylate (PMMA), polystyrene (PS), silicon, titanium dioxide (TiO 2 ), and silicon dioxide (SiO 2 ), or a combination thereof. Further, the scattering particles  231  may be formed of a material having a refractive index less than the formation material of the second layer  230 . For example, the scattering particles  231  may be formed by generating bubbles in the second layer  230 . Other materials may be used for the second layer  230 . For example, the scattering particle  231  may be formed using various polymer materials or inorganic particles. 
     An optical sheet  250  may be disposed on the top of the second layer  230 . The optical sheet  250  may include at least one prism sheet  251  and/or at least one diffusion sheet  252 . In this case, a plurality of sheets constituting the optical sheet  250  are not separated from one another and are attached to one another. Thus, the thickness of the optical sheet  250  or the thickness of the backlight unit  200  may be reduced because of the above structure of the optical sheet  250 . 
     A lower surface of the optical sheet  250  may closely adhere to the second layer  230 , and an upper surface of the optical sheet  250  may closely adhere to the lower surface of the display panel  100 , e.g., the lower polarizing plate  140 . 
     The diffusion sheet  252  may diffuse incident light to thereby prevent light output from the second layer  230  from being partially concentrated. Hence, the diffusion sheet  252  may further uniformize the luminance of light. Further, the prism sheet  251  may focus light output from the diffusion sheet  252 , thereby allowing the light to be vertically incident on the display panel  100 . 
     In the embodiment of the invention, at least one of the prism sheet  251  and the diffusion sheet  252  constituting the optical sheet  250  may be removed. The optical sheet  250  may further include other functional layers in addition to the prism sheet  251  and the diffusion sheet  252 . 
     The reflection layer  240  may include a plurality of holes at locations corresponding to the formation locations of the light sources  220 , and the light sources  220  on the first layer  210  underlying the reflection layer  240  may be inserted into the holes. These holes may be indents in the first layer  210  or can be merely through holes defined by the reflection layer  240 . 
     In this case, the light sources  220  are downwardly inserted into the holes of the reflection layer  240 , and at least a portion of each of the light sources  220  may protrude from the upper surface of the reflection layer  240 . Because the backlight unit  200  is configured using the structure in which the light sources  220  are respectively inserted into the holes of the reflection layer  240 , a fixation strength between the first layer  210  and the reflection layer  240  may be further improved. 
       FIG. 7  illustrates a third exemplary configuration of a backlight unit according to the embodiment of the invention. Structures and components identical or equivalent to those described in the first and second exemplary configurations may be designated with the same reference numerals in the third exemplary configuration, and a further description may be briefly made or may be entirely omitted. 
     As shown in  FIG. 7 , each of the plurality of light sources  220  of the backlight unit  200  has the light emitting surface on the side thereof and may emit light in a lateral direction. e.g., a direction in which the first layer  210  or the reflection layer  240  extends. 
     For example, the plurality of light sources  220  may be configured using the side view type LED package. As a result, it is possible to address a problem that the light sources  220  are observed as a hot spot on the screen and to slim the backlight unit  200 . Furthermore, the thin profile of the display device  1  may be achieved because of a reduction of the thickness “a” of the second layer  230 . 
     In this case, the light sources  220  may emit light having a predetermined orientation angle of for example, 90° to 150° about a first direction x (indicated by an arrow). Hereinafter, a direction of light emitted from the light sources  220  is indicated as the first direction x. 
     In the embodiment of the invention, light is emitted and diffused upwardly from the light sources  220  by forming a pattern on the second layer  230 , and thus the backlight unit  200  may emit light having the uniform luminance. 
       FIGS. 8 to 13  illustrate a fourth exemplary configuration of a backlight unit according to the embodiment of the invention. Structures and components identical or equivalent to those described in the first to third exemplary configurations may be designated with the same reference numerals in the fourth exemplary configuration, and a further description may be briefly made or may be entirely omitted. 
     The light sources  220  illustrated in  FIGS. 8 to 13  may emit light from the side of the light sources  220  in a lateral direction in the same or similar manner as  FIG. 7 . Other manners may be used. For example, the light sources  220  may emit light from the top of the light sources  220 , e.g., the light may be emitted in an upward direction. 
     As shown in  FIG. 8 , a pattern layer including a plurality of first patterns  232  may be formed on the top of the second layer  230  of the backlight unit  200  including the light sources  220 . More specifically, the plurality of first patterns  232  of the pattern layer may be formed on the second layer  230  at locations corresponding to the formation locations of the light sources  220 . For instance, for each light source  220 , one of the first patterns  232  is provided. 
     For example, the first patterns  232  formed on the top of the second layer  230  may be a first pattern capable of reflecting at least a portion of light emitted from the light sources  220 . 
     A luminance of the light emitted from an area adjacent to the light sources  220  may decrease by forming the first patterns  232  on the second layer  230 , and thus the backlight unit  200  may emit light having the uniform luminance. 
     In other words, the first patterns  232  are formed on the second layer  230  at the locations corresponding to the formation locations of the light sources  220  and selectively reflect light emitted from the light sources  220 , thereby reducing the luminance of light from the area adjacent to the light sources  220 . The reflected light may be diffused in a lateral direction. 
     More specifically, the light emitted upward from the light sources  220  is diffused in the lateral direction by the first patterns  232 , and at the same time is reflected downward. The light reflected from the first patterns  232  is again diffused in the lateral direction by the reflection layer  240 , and at the same time is reflected upward. In other words, the first patterns  232  may reflect 100% of incident light. Alternatively, the first patterns  232  may reflect a portion of the incident light and may transmit a portion of the incident light. As above, the first patterns  232  may control the transfer of light passing through the second layer  230  and the first patterns  232 . As a result, the light emitted from the light sources  220  may be widely diffused in the lateral direction and other directions as well as the upward direction, and thus the backlight unit  200  may emit the light having the uniform luminance. 
     The first patterns  232  include a reflection material such as metal. For example, the first patterns  232  may include metal having a reflectance of 90% or more such as aluminum, silver, and gold. For example, the first patterns  232  may be formed of a material capable of transmitting 10% or less of incident light and reflecting 90% or more of the incident light. 
     In this case, the first patterns  232  may be formed by depositing or coating the above-described metal. As another method, the first patterns  232  may be formed through a printing process using a reflection ink including a metal, for example, a silver ink in accordance with a previously determined pattern. 
     Further, the first patterns  232  may have a color having a high brightness, for example, a color close to white so as to improve a reflection effect of the first patterns  232 . More specifically, the first pattern  232  may have a color having a brightness greater than the second layer  230 . 
     The first patterns  232  may contain metal oxide. For example, the first patterns  232  may include titanium dioxide (TiO 2 ). More specifically, the first patterns  232  may be formed by printing a reflection ink containing titanium dioxide (TiO 2 ) in accordance with a previously determined pattern. 
     As shown in  FIGS. 9 to 13 , the formation of the first patterns  232  at the locations corresponding to the locations of the light sources  220  may include the case where a middle portion of the first pattern  232  coincides with a middle portion of the light source  220  corresponding to the first pattern  23  as shown in  FIG. 8  and the case where the middle portion of the first pattern  232  is spaced from the middle portion of the corresponding light source  220  by a predetermined distance. 
     As shown in  FIG. 9 , the middle portion of the first pattern  232  may not coincide with the middle portion of the light source  220  corresponding to the first pattern  232 . 
     For example, when the light emitting surface of the light source  220  faces not the upward direction but the lateral direction and therefore light is emitted from the light source  220  in the lateral direction, a luminance of light emitted from the side of the light source  220  may decrease while the light emitted from the side of the light source  220  travels through the second layer  230  in a direction indicated by an arrow of  FIG. 9 . Hence, light in a first area directly adjacent to the light emitting surface of the light source  220  may have a luminance greater than light in an area around the light emitting surface of the light source  220 . Light in a second area adjacent to an opposite direction of the light emitting surface may have a luminance less than the light in the first area. Thus, the first pattern  232  may be formed by moving in an emission direction of light from the light source  220 . In other words, the middle portion of the first pattern  232  may be formed at a location slightly deviated from the middle portion of the corresponding light source  220  toward the light emitting direction. 
     As shown in  FIG. 10 , the first pattern  232  may be formed at a location deviated further than the first pattern  232  illustrated in  FIG. 9  toward the light emitting direction. In other words, a distance between the middle portion of the first pattern  232  and the middle portion of the corresponding light source  220  in  FIG. 10  may be longer than a distance between the middle portion of the first pattern  232  and the middle portion of the corresponding light source  220  in  FIG. 9 . For example, the light emitting surface of the light source  220  may overlap or be aligned with an end portion of the first pattern  232 . 
     As shown in  FIG. 11 , the first pattern  232  may be formed at a location deviated further than the first pattern  232  illustrated in  FIG. 10  toward the light emitting direction. In other words, a formation area of the first pattern  232  may not overlap a formation area of the corresponding light source  220 . Hence, an end portion of the first pattern  232  may be separated from the light emitting surface of the light source  220  by a predetermined distance. 
     As shown in  FIG. 12 , the first pattern  232  may be formed inside the second layer  230 . In this case, the middle portion of the first pattern  232  may be formed at a location corresponding to the light source  220 . In variations, the first pattern  232  may be formed in the same manners as  FIGS. 9 to 11 , except that the first pattern  232  is disposed within the second layer  230 . 
     As shown in  FIG. 13 , the first pattern  232  may be manufactured in a sheet form. In this case, the pattern layer including the plurality of first patterns  232  may be formed on the second layer  230 . 
     For example, after the plurality of first patterns  232  are formed on one surface of a transparent film  260  through the printing process, etc. to form the pattern layer, the pattern layer including the transparent film  260  may be stacked on the second layer  230 . More specifically, a plurality of dots may be printed on the transparent film  260  to form the first patterns  232 . 
     As a percentage of a formation area of the first pattern  232  in the second layer  230  increases, an aperture ratio decreases. Hence, the entire luminance of light which the backlight unit  200  provides to the display panel  100  may decrease. The aperture ratio may indicate the size of an area of the second layer  230  that is not occupied by the first pattern  232 . 
     Thus, the aperture ratio of the pattern layer including the first patterns  232  may be equal to or greater than 70%, so as to prevent the degradation of the image quality resulting from an excessive reduction in the luminance of light provided to the display panel  100 . That is, the percentage of the area of the second layer  230  occupied by the first pattern  232  is equal to or less 30% of the total area of the second layer  230 . 
       FIGS. 14 to 17  are top views of the backlight unit  200  for illustrating a disposition of the first patterns  232  formed in the backlight unit  200 . In these figures, although the light sources  220  may not be fully visible from the top since they may be disposed below the first patterns  232 , the light sources  220  are clearly drawn merely to illustrate their locations with respect to the first patterns  232 . As described above, the first patterns  232  may be formed at locations corresponding to the light sources  220 ; e.g., above or adjacent to the light sources. 
     As shown in  FIG. 14 , each first pattern  232  may have a circle shape or an oval shape around a formation location of the corresponding light source  220 . Other shapes, colors, and/or sizes may be used for the first pattern  232 . The middle portion of the first pattern  232  may be formed at a location deviated slightly from the middle portion of the corresponding light source  220  toward the light emitting direction in the same manner as  FIGS. 9 to 11 . 
     As shown in  FIG. 15 , the first pattern  232  may be off-centered with respect to the corresponding light sources  220  in the light emitting direction (e.g., an x-axis direction in  FIG. 15 ). Hence, the middle portion of the first pattern  232  may be formed at a location deviated from the middle portion of the corresponding light source  220  toward the light emitting direction by a predetermined distance. 
     As shown in  FIG. 16 , the first pattern  232  may be off-centered toward the light emitting direction further than the first pattern  232  shown in  FIG. 15 . Hence, a portion of a formation area of the light source  220  may overlap a formation area of the first pattern  232 . 
     As shown in  FIG. 17 , the first pattern  232  may be off-centered toward the light emitting direction further than the first pattern  232  shown in  FIG. 16  and thus may be positioned outside a formation area of the light source  220 . Hence, a formation area of the light source  220  may not overlap a formation area of the first pattern  232 . 
       FIGS. 18 to 21  illustrate various shapes of the first pattern  232 . For instance, each of the first patterns  232  discussed above can have the configuration shown in  FIG. 18 ,  19 ,  20 , or  21 . In  FIGS. 18 to 21 , the first pattern  232  may be configured by the plurality of dots or regions, and each dot or each region may contain a reflection material, for example, metal or metal oxide. 
     As shown in  FIG. 18 , the first pattern  232  may have a circle shape around the formation location of the light source  220 . Other shapes such as a diamond may be used. A reflectance of the first pattern  232  may decrease as the first pattern  232  goes from a middle portion  234  of the first pattern  232  to the outside. The reflectance of the first pattern  232  may gradually decrease as the first pattern  232  goes from the middle portion  234  to the outside, because the number of dots or a reflectance of a material forming the first pattern  232  decreases as the first pattern  232  goes from the middle portion  234  to the outside. 
     Further, as the first pattern  232  extends from the middle portion  234  to the outwardly direction, a transmittance or an aperture ratio of the light processed by the first pattern  232  may increase. Hence, the formation location of the light source  220 , more specifically, the middle portion  234  of the first pattern  232  corresponding to the middle portion of the light source  220  may have a maximum reflectance (for example, the middle portion  234  having the maximum reflectance does not transmit most of light) and a minimum transmittance or a minimum aperture ratio. As a result, the hot spot generated when light is concentrated in the formation area of the light source  220  may be more effectively prevented. 
     For example, an aperture ratio of the middle portion of the first pattern  232  overlapping the light source  220  may be equal to or less than 5% so as to prevent the generation of the hot spot. 
     In the plurality of dots  233  constituting the first pattern  232 , a distance between the adjacent dots  233  may increase as the first pattern  232  goes from the middle portion  234  to the outside. Hence, as described above, as the first pattern  232  goes from the middle portion  234  to the outside, the transmittance or the aperture ratio of the first pattern  232  may increase while the reflectance of the first pattern  232  decreases. 
     As shown in  FIG. 19 , the first pattern  232  may have an oval shape. The middle portion  234  of the first pattern  232  may coincide with the middle portion of the corresponding light source  220 . Alternatively, the middle portion  234  of the first pattern  232  may not coincide with the middle portion of the corresponding light source  220 . In other words, the middle portion  234  of the first pattern  232  may be formed at a location deviated from the middle portion of the corresponding light source  220  toward one direction (for example, a light emitting direction of the corresponding light source  220 ) in the same manner as  FIGS. 9 to 11 . 
     In this case, as the first pattern  232  extends from a portion  237  of the first pattern  232  corresponding to the middle portion of the light source  220  to the outwardly direction, the reflectance of the first pattern  232  may decrease or the transmittance of the first pattern  232  may increase. That is, the portion  237  of the first pattern  232  may be positioned at a location deviated from the middle portion  234  of the first pattern  232  in one direction. The portion  237  of the first pattern  232  may have a maximum reflectance or a minimum transmittance. 
     As shown in  FIGS. 20 and 21 , the first pattern  232  may have a rectangular shape around the formation location of the light source  220 . As the first pattern  232  extends from the middle portion to the outwardly direction, a reflectance of the first pattern  232  may decrease and a transmittance or an aperture ratio may increase. 
     The first rectangular pattern  232  shown in  FIGS. 20 and 21  may have the same characteristics as the first pattern  232  shown in  FIGS. 18 and 19 . For example, an aperture ratio of the middle portion of the first pattern  232  overlapping the light source  220  may be equal to or less than 5% so as to prevent the generation of the hot spot. 
     Further, as shown in  FIGS. 20 and 21 , in the plurality of dots  233  constituting the first pattern  232 , a distance between the adjacent dots  233  may increase from the middle portion of the first pattern  232  to the outwardly direction. 
     In the embodiment of the invention, the first pattern  232  is configured to include the plurality of dots as shown in  FIGS. 18 to 21 . However, other configurations may be used. The first pattern  232  may have any configuration as long as the reflectance of the first pattern  232  decreases and the transmittance or the aperture ratio of the first pattern  232  increases as one moves from the middle portion of the first pattern  232  to the outwardly direction. 
     For example, as the first pattern  232  extends from the middle portion to the outwardly direction, a concentration of a reflection material, for example, metal or metal oxide may decrease. Hence, the reflectance of the first pattern  232  may decrease and the transmittance or the aperture ratio of the first pattern  232  may increase. As a result, the concentration of light in an area adjacent to the light source  220  may be reduced. 
       FIGS. 22 and 23  illustrate a fifth exemplary configuration of a backlight unit according to the embodiment of the invention. Structures and components identical or equivalent to those described in the first to fourth exemplary configurations may be designated with the same reference numerals in the fifth exemplary configuration, and a further description may be briefly made or may be entirely omitted. 
     As shown in  FIG. 22 , the first pattern  232  may have a convex shape protruding toward the light source  220 . For example, the first pattern  232  may have a shape similar to a semicircle. A cross-sectional shape of the first pattern  232  may have a semicircle shape or an oval shape protruding toward the light source  220 . 
     The first pattern  232  having the convex shape may reflect incident light at various angles. Hence, the first pattern  232  may uniformize the luminance of light emitted upward from the second layer  230  by diffusing more widely light emitted from the light source  220 . 
     The first pattern  232  may include the reflection material such as metal or metal oxide as described above. For example, the first pattern  232  may be formed by forming a pattern on the top of the second layer  230  by an intaglio method and then filling the intaglio pattern with a reflection material. Alternatively, the first pattern  232  may be formed on the top of the second layer  230  by printing the reflection material on a film type sheet or attaching beads or metallic particles to the film type sheet and then pressing the film type sheet onto the second layer  230 . 
     A cross-sectional shape of the first pattern  232  may have various shapes protruding toward the light source  220  in addition to a shape similar to the semicircle shown in  FIG. 22 . For example, as shown in  FIG. 23 , the cross-sectional shape of the first pattern  232  may have a triangular shape protruding toward the light source  220 . In this case, the first pattern  232  may have a pyramid shape or a prism shape. 
       FIG. 24  illustrates a sixth exemplary configuration of a backlight unit according to the embodiment of the invention. Structures and components identical or equivalent to those described in the first to fifth exemplary configurations may be designated with the same reference numerals in the sixth exemplary configuration, and a further description may be briefly made or may be entirely omitted. 
     Referring to  FIG. 24 , light emitted from the light source  220  may be diffused by the second layer  230  and may be emitted upward. Further, the second layer  230  includes the plurality of scattering particles  231  to scatter or refract the upward emitted light, thereby making the luminance of the upward emitted light more uniform. 
     In the embodiment of the invention, a third layer  235  may be disposed on top of the second layer  230 . The third layer  235  may be formed of the same material as or a different material from the second layer  230  and may improve the uniformity of the luminance of the light of the backlight unit  200  by diffusing the light emitted upward from the second layer  230 . 
     The third layer  235  may be formed of a material having a refractive index equal to or different from a refractive index of a material forming the second layer  230 . For example, when the third layer  235  is formed of a material having a refractive index greater than the second layer  230 , the third layer  235  may more widely diffuse the light emitted from the second layer  230 . In contrast, when the third layer  235  is formed of a material having a refractive index less than the second layer  230 , a reflectance of light, which is emitted from the second layer  230  and is reflected on the bottom of the third layer  235 , may be improved. Hence, the third layer  235  may allow the light emitted from the light source  220  to easily travel along the second layer  230 . 
     The third layer  235  may also include a plurality of scattering particles  236 . In this case, a density of the scattering particles  236  of the third layer  235  may be greater higher than a density of the scattering particles  231  of the second layer  230 . 
     As described above, because the third layer  235  includes the scattering particles  236  having the density greater than the scattering particles  231  of the second layer  230 , the third layer  235  may more widely diffuse the light emitted upward from the second layer  230 , thereby making the luminance of the light emitted from the backlight unit  200  more uniform. 
     In the embodiment of the invention, the first pattern  232  explained by referring to  FIGS. 7 to 19  may be formed between the second layer  230  and the third layer  235  or inside at least one of the second layer  230  and the third layer  235 . 
     As shown in  FIG. 24 , another pattern layer may be formed on top of the third layer  235 . The pattern layer on the third layer  235  may include a plurality of second patterns  265 . 
     The second patterns  265  on top of the third layer  235  may be reflection patterns capable of reflecting at least a portion of light emitted from the second layer  230 . Thus, the second patterns  265  may further uniformize the luminance of light emitted from the third layer  235 . 
     For example, when the light emitted upward from the third layer  235  is concentrated in a predetermined portion and is observed as light having a high luminance on the screen, the second patterns  265  may be formed in a region corresponding to the predetermined portion of the top of the third layer  235 . Hence, the second patterns  265  may uniformize the luminance of light emitted from the backlight unit  200  by reducing the luminance of the light in the predetermined portion. 
     The second pattern  265  may be formed of titanium dioxide (TiO 2 ). In this case, a portion of light emitted from the third layer  235  may be reflected downward from the second patterns  265  and a remaining portion of the light emitted from the third layer  235  may be transmitted. 
     As shown in  FIG. 25 , a thickness h 1  of the second layer  230  may be less than a height h 3  of the light source  220  or  225 . Hence, the second layer  230  may cover a portion of a lower part of the light source  220 , and the third layer  235  may cover a portion of an upper part of the light source  220 . 
     The second layer  230  may be formed of resin having a high adhesive strength. For example, an adhesive strength of the second layer  230  may be greater than the third layer  235 . Hence, the light emitting surface of the light source  220  may be strongly attached to the second layer  230 , and a space between the light emitting surface of the light source  220  and the second layer  230  may not be formed. 
     In the embodiment of the invention, the second layer  230  may be formed of silicon-based resin having a high adhesive strength, and the third layer  235  may be formed of acrylic resin. In this case, the refractive index of the second layer  230  may be greater than the refractive index of the third layer  235 , and each of the second and third layers  230  and  235  may have the refractive index of approximately 1.4 to 1.6. Further, a thickness h 2  of the third layer  235  may be less than the height h 3  of the light source  220 . 
       FIG. 26  illustrates a location relationship between the light source  220  and the reflection layer  240  of the backlight unit according to an embodiment of the invention. 
     As shown in  FIG. 26 , because the reflection layer  240  is disposed at the side of the light source  220 , a portion of light emitted from the light source  220  toward the side of the light source  220  may be incident on the reflection layer  240  and may be lost. 
     The loss of light emitted from the light source  220  can decrease an amount of the light that is incident on the second layer  230  and then passes through the second layer  230 . Hence, an amount of light incident on the display panel  100  from the backlight unit  200  may decrease. As a result, the luminance of the image displayed on the display device may be reduced. 
     Each of the light sources  220  may include a light emitting unit  222  (e.g., LED) emitting light. The light emitting unit  222  may be positioned at a location separated from the surface of the first layer  210  by a predetermined height “c”. 
     The thickness “b” of the reflection layer  240  may be equal to or less than the height “c” of the light emitting unit  222 . Hence, the light source  220  may be positioned above the reflection layer  240 . 
     Accordingly, the thickness “b” of the reflection layer  240  may be approximately 10 nm to 100 μm. When the thickness “b” of the reflection layer  240  is equal to or greater than 10 nm, the reflection layer  240  may have a light reflectance within a reliable range. When the thickness “b” of the reflection layer  240  is equal to or less than 100 μm, the reflection layer  240  may cover the light emitting unit  222  of the light source  220 . Hence, a loss of light emitted from the light source  220  may be prevented. 
     Accordingly, the thickness “b” of the reflection layer  240  may be approximately 10 nm to 100 μm, so that the reflection layer  240  improves an incident efficiency of light emitted from the light source  220  and reflects most of light emitted from the light source  220 . 
       FIGS. 27 and 28  illustrate a structure of a light source of a backlight unit according to an embodiment of the invention. More specifically,  FIG. 27  illustrates the structure of the light source when viewed from the side of the light source, and  FIG. 28  illustrates a structure of a head part of the light source when viewed from the front of the light source. 
     As shown in  FIG. 27 , the light source  220  may include a light emitting element  321 , a mold part  322  having a cavity  323 , and a plurality of lead frames  324  and  325 . 
     In the embodiment of the invention, the light emitting element  321  may be a light emitting diode (LED) chip. The LED chip may be configured by a blue LED chip or an infrared LED chip or may be configured by at least one of a red LED chip, a green LED chip, a blue LED chip, a yellow green LED chip, and a white LED chip or a combination thereof. 
     Hereinafter, the embodiment of the invention will be described using a case in which the light source  220  is configured to include the LED chip  321  as the light emitting device as an example. 
     The LED chip  321  may be packaged in the mold part  322  constituting a body of the light source  220 . For this, the cavity  323  may be formed at one side of the center of the mold part  322 . The mold part  322  may be injection-molded with a resin material such as polyphtalamide (PPA) to a press (Cu/Ni/Ag substrate), and the cavity  323  of the mold part  322  may serve as a reflection cup. The shape or structure of the mold part  322  may be changed and is not limited thereto. 
     Each of the lead frames  324  and  325  may penetrate the mold part  322  in a long axis direction of the mold part  322 . Ends  326  and  327  of the lead frames  324  and  325  may be exposed to the outside of the mold part  322 . Herein, when viewed from the bottom of the cavity  323  where the LED chip  321  is disposed, a long-direction symmetrical axis of the mold part  322  is referred to as a long axis and a short-direction symmetrical axis of the mold part  322  is referred to as a short axis. 
     A semiconductor device such as a light receiving element and a protection element may be selectively mounted on the lead frames  324  and  325  in the cavity  323  along with the LED chip  321 . For instance, the protection device such as a zener diode for protecting the LED chip  321  from electrostatic discharge (ESD) may be mounted on the lead frames  324  and  325  along with the LED chip  321 . 
     The LED chip  321  may attach to any one lead frame (for example, the lead frame  325 ) positioned on the bottom of the cavity  323 , and then may be bonded by wire bonding or flip chip bonding. 
     Further, after the LED chip  321  is connected to the lead frame  325  in the cavity  323 , a resin and a phosphor that are a color conversion layer may be molded to the mounting region. The resin includes silicon or an epoxy material. The phosphor may be yellow depending on a color of light that the LED chip  321  emits. For example, when the LED chip  321  emits blue light, the yellow phosphor may convert the blue light into white light. The color conversion layer may be formed in any one form of a flat form in which the surface of the color conversion layer is molded with the same height as the top of the cavity  323 , a concave lens form concaved to the top of the cavity  323 , and a convex lens form protruding to the top of the cavity  323 . 
     At least one side of the cavity  323  may be inclined, and the inclined side of the cavity  323  may serve as a reflection surface (not shown) or a reflection layer (not shown) for selectively reflecting incident light. The cavity  323  may have a polygonal exterior shape and may have other shapes other than a polygonal shape. 
     As shown in  FIG. 28 , a head part of the light source  220  corresponding to a light emitting part may include a light emitting surface actually emitting light and a non-emitting surface which is a part other than the light emitting surface and does not emit light. 
     More specifically, the light emitting surface of the head part  322  of the light source  220  may be formed by the mold part  322  and may be defined by the cavity  323  in which the LED chip  321  is positioned. For example, the LED chip  321  may be disposed in the cavity  323  of the mold part  322 , and light emitted from the LED chip  321  may be emitted through the light emitting surface surrounded by the mold part  322 . Further, the non-emitting surface of the head part of the light source  220  may be a part where the mold part  322  is formed and the light is not emitted. 
     Further, as shown in  FIG. 28 , the light emitting surface of the head part of the light source  220  may have a shape in which a transverse length is longer than a longitudinal length. Other shapes may be used for the light emitting surface of the head part. For example, the light emitting surface may have a rectangular shape. 
     In addition, the non-emitting surface of the light source  220  may be positioned at upper, lower, left, or right side of the light emitting surface of the head part  332  of the light source  220 . 
     The ends  326  and  327  of the lead frames  324  and  325  may be first formed to extend to the outside of the mold part  322  and then may be secondly formed in one groove of the mold part  322 . Hence, the ends  326  and  327  may be disposed in first and second lead electrodes  328  and  329 . Herein, the number of such forming steps may vary. 
     The first and second lead electrodes  328  and  329  of the lead frames  324  and  325  may be formed to be received in grooves formed at both sides of the bottom of the mold part  322 . Further, the first and second lead electrodes  328  and  329  may be formed to have a plate structure of a predetermined shape and may have a shape in which solder bonding is easy performed in surface mounting. 
       FIG. 29  illustrates a structure of the light sources of a backlight unit according to an embodiment of the invention. 
     As shown in  FIG. 29 , the first light source  220  and the second light source  225  of the plurality of light sources  220  of the backlight unit  200  may emit light in different directions. 
     For example, the first light source  220  may emit the light in the lateral direction. For this, the first light source  220  may be configured using the side view type LED package. The second light source  225  may emit the light in the upward direction. For this, the second light source  225  may be configured using the top view type LED package. In other words, the plurality of light sources  220  of the backlight unit  200  may be configured by combining the side view type LED packages and the top view type LED packages. 
     As described above, because the backlight unit  200  is configured by combining two or more light sources that emit light in different directions, an increase and a reduction in the luminance of light in a predetermined area may be prevented. As a result, the backlight unit  200  may provide light with the uniform luminance to the display panel  100 . 
     In  FIG. 29 , the embodiment of the invention is described using a case where the first light source  220  emitting the light in the lateral direction and the second light source  225  emitting the light in the upward direction are disposed adjacent to each other as an example, but the invention is not limited thereto. For example, the side view type light sources may be disposed adjacent to each other or the top view type light sources may be disposed adjacent to each other. 
       FIGS. 30 to 34  illustrate a front shape of the backlight unit including light sources according to the exemplary embodiment of the invention. The light sources in these figures can be have any configuration discussed in any of the embodiments discussed herein. 
     As shown in  FIG. 30 , the plurality of light sources  220  and  221  of the backlight unit  200  may be divided into a plurality of arrays, for example, a first light source array A 1  and a second light source array A 2 . 
     Each of the first light source array A 1  and the second light source array A 2  may include a plurality of light source lines each including light sources. For example, the first light source array A 1  may include a plurality of light source lines L 1  each including at least two light sources, and the second light source array A 2  may include a plurality of light source lines L 2  each including at least two light sources 
     The plurality of light source lines L 1  of the first light source array A 1  and the plurality of light source lines L 2  of the second light source array A 2  may be alternately disposed so as to correspond to the display area of the display panel  100 . 
     In the embodiment of the invention, the first light source array A 1  may include odd-numbered light source lines each including at least two light sources from the top of the plurality of light source lines, and the second light source array A 2  may include even-numbered light source lines each including at least two light sources from the top of the plurality of light source lines. 
     In the embodiment of the invention, the backlight unit  200  may be configured so that a first light source line L 1  of the first light source array A 1  and a second light source line L 2  of the second light source array A 2  are disposed adjacent to each other up and down and the first light source line L 1  and the second light source line L 2  are alternately disposed. 
     Further, the light source  220  of the first light source array A 1  and the light source  221  of the second light source array A 2  may emit light in the same direction or in different directions. 
     As shown in  FIG. 31 , the backlight unit  200  may include two or more light sources that emit light in different directions. 
     For instance, the light sources  220  of the first light source array A 1  and the light sources  221  of the second light source array A 2  may emit light in different directions. For this, a facing direction of light emitting surfaces of the light sources  220  of the first light source array A 1  face may be different from a facing direction of light emitting surfaces of the light sources  221  of the second light source array A 2 . 
     More specifically, the light emitting surface of the first light source  220  of the first light source array A 1  and the light emitting surface of the second light source  221  of the second light source array A 2  may face in opposite directions or substantially directions. Hence, the first light source  220  of the first light source array A 1  and the second light source  221  of the second light source array A 2  may emit light in opposite directions or substantially directions. In this case, each of the light sources of the backlight unit  200  may emit light in the lateral direction and may be configured by using the side view-type LED package. 
     The plurality of light sources of the backlight unit  200  may be disposed while forming two or more lines. Two or more light sources on the same line may emit light in the same direction. For example, light sources, adjacent to right and left sides of the first light source  220  may emit light in the same direction as the first light source  220 , e.g., in the opposite direction of the x-axis direction. Light sources adjacent to right and left sides of the second light source  221  may emit light in the same direction as the second light source  221 , e.g., in the x-axis direction. 
     As described above, the light sources (for example, the first light source  220  and the second light source  221 ) disposed adjacent to each other in a y-axis direction may be configured so that their light emitting direction are opposite or substantially opposite to each other. Hence, the luminance of light emitted from the light sources may be prevented from being increased or reduced in a predetermined area of the backlight unit  200 . 
     That is, because light emitted from the first light source  220  travels toward the light source adjacent to the first light source  220 , a luminance of light may be reduced. As a result, the luminance of the light, which is emitted from the first light source  220 , travels to an area distant from the first light source  220 , and is emitted from the area in a direction of the display panel  100 , may be reduced. 
     Accordingly, because the first light source  220  and the second light source  221  emit light in the opposite directions in the embodiment of the invention, a luminance of light emitted from the first light source  220  and the second light source  221  may be complementarily prevented from increasing in the area adjacent to the light source and from being reduced in the area distant from the light source. Hence, the luminance of light provided by the backlight unit  200  may be uniformized. 
     Further, the light sources of the first light source line L 1  of the first light source array A 1  and the light sources of the second light source line L 2  of the second light source array A 2  may not disposed in the straight line in a vertical direction and may be staggered in the vertical direction. As a result, the uniformity of light emitted from the backlight unit  200  may be improved. That is, the first light source  220  of the first light source array A 1  and the second light source  221  of the second light source array A 2  may be disposed adjacent to each other in a diagonal direction. 
     As shown in  FIG. 32 , two vertically adjacent light source lines (for example, the first and second light source lines L 1  and L 2 ) respectively included in the first and second light source arrays A 1  and A 2  may be separated from each other by a predetermined distance d 1 . In other words, the first light source  220  of the first light source array A 1  and the second light source  221  of the second light source array A 2  may be separated from each other by the predetermined distance d 1  based on the y-axis direction perpendicular to an x-axis being a light emitting direction. 
     As the distance d 1  between the first and second light source lines L 1  and L 2  increases, an area where light emitted from the first light source  220  or the second light source  221  cannot reach may be generated. Thus, the luminance of light in the non-reach area of light may be reduced. Further, as the distance d 1  between the first and second light source lines L 1  and L 2  decreases, the light emitted from the first light source  220  and the light emitted from the second light source  221  may interfere with each other. In this case, the division driving efficiency of the light sources may be deteriorated. 
     Accordingly, the distance d 1  between the adjacent light source lines (for example, the first and second light source lines L 1  and L 2 ) in a crossing direction of the light emitting direction may be approximately 5 mm to 22 mm, so as to uniformize the luminance of light provided by the backlight unit  200  while reducing the interference between the light sources. 
     Further, the third light source  222  included in the first light source line L 1  of the first light source array A 1  may be disposed adjacent to the first light source  220  in the light emitting direction. The first light source  220  and the third light source  222  may be separated from each other by a predetermined distance d 2 . 
     A light orientation angle θ from the light source and a light orientation angle θ′ inside the second layer  230  may satisfy the following Equation 1 in accordance with Snell&#39;s law. 
     
       
         
           
             
               
                 
                   
                     
                       n 
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                        
                       1 
                     
                     
                       n 
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                        
                       2 
                     
                   
                   = 
                   
                     
                       sin 
                        
                       
                           
                       
                        
                       
                         θ 
                         ′ 
                       
                     
                     
                       sin 
                        
                       
                           
                       
                        
                       θ 
                     
                   
                 
               
               
                 
                   [ 
                   
                     Equation 
                      
                     
                         
                     
                      
                     1 
                   
                   ] 
                 
               
             
           
         
       
     
     Considering that a light emitting portion of the light source is an air layer (having a refractive index n1 of 1) and the orientation angle θ of light emitted from the light source is generally 60°, the light orientation angle θ′ inside the second layer  230  may have a value indicated in the following Equation 2 in accordance with the above Equation 1. 
     
       
         
           
             
               
                 
                   
                     sin 
                      
                     
                         
                     
                      
                     
                       θ 
                       ′ 
                     
                   
                   = 
                   
                     
                       sin 
                        
                       
                           
                       
                        
                       
                         60 
                         ° 
                       
                     
                     
                       n 
                        
                       
                           
                       
                        
                       2 
                     
                   
                 
               
               
                 
                   [ 
                   
                     Equation 
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                      
                     2 
                   
                   ] 
                 
               
             
           
         
       
     
     Further, when the second layer  230  is formed of an acrylic resin such as polymethyl methacrylate (PMMA), the second layer  230  has a refractive index of approximately 1.5. Therefore, the light orientation angle θ′ inside the second layer  230  may be approximately 35.5° in accordance with the above Equation 2. 
     As described with reference to the above Equations 1 and 2, the light orientation angle θ′ of the light emitted from the light source in the second layer  230  may be less than 45°. As a result, a travelling range of light emitted from the light source in the y-axis direction may be less than a travelling range of the light emitted from the light source in the x-axis direction. 
     Accordingly, the distance d 1  between two adjacent light sources (for example, the first and second light sources  220  and  221 ) in a crossing direction of the light emitting direction may be smaller than the distance d 2  between two adjacent light sources (for example, the first and third light sources  220  and  222 ) in the light emitting direction. As a result, the luminance of the light emitted from the backlight unit  200  can be uniformized. 
     Considering the distance d 1  between the two adjacent light sources having the above-described range, the distance d 2  between two adjacent light sources (for example, the first and third light sources  220  and  222 ) in the light emitting direction may be approximately 9 mm to 27 mm, so as to uniformize the luminance of the light emitted from the backlight unit  200  while reducing the interference between the light sources. 
     As shown in  FIG. 32 , the second light source  221  of the second light source array A 2  may be disposed between the adjacent first and third light sources  220  and  222  included in the first light source array A 1 . 
     That is, the second light source  221  may be disposed adjacent to the first light source  220  and the third light source  222  in the y-axis direction and may be disposed on a straight line l passing between the first light source  220  and the third light source  222 . In this case, a distance d 3  between the straight line l on which the second light source  221  is disposed and the first light source  220  may be greater than a distance d 4  between the straight line l and the third light source  222 . 
     Light emitted from the second light source  221  travels in the opposite direction to a light emitting direction of the third light source  222 , and thus the luminance of light emitted toward the display panel  100  may be reduced in an area adjacent to the third light source  222 . 
     Accordingly, in the embodiment of the invention, because the second light source  221  is disposed closer to the third light source  222  than to the first light source  220 , the reduction in the luminance of light in the area adjacent to the third light source  222  may be compensated using an increase in the luminance of light in the area adjacent to the second light source  221 . 
     At least one of the plurality of light sources  220  of the backlight unit  200  may emit light in a horizontal direction, i.e., in a direction slightly inclined to the x-axis direction. For example, as shown in  FIG. 33 , facing directions of the light emitting surfaces of the light sources  220  and  221  may be upwardly or downwardly inclined to the x-axis direction by a predetermined angle. 
     As shown in  FIG. 34 , the light sources  220 ,  221 , and  224  respectively included in the light source lines L 1 , L 2 , and L 3  may be staggered. For example, the light sources included in the light source lines L 1 , L 3 , and L 2  of the first light source array A 1  and the light sources included in the light source lines L 2 , L 1 , and L 3  of the second light source array A 2  may be staggered. Hence, the light source lines L 1 , L 3 , and L 2  of the first light source array A 1  and the light source lines L 2 , L 1 , and L 3  of the second light source array A 2  may be alternately disposed. The light sources  220 ,  221 ,  222 , and  224  may be the same type of light sources. However, the light sources  220 ,  221 ,  222 , and  224  may emit light in different directions or may be different types of light sources, if desired. 
       FIGS. 35 to 38  illustrate a structure of the reflection layer of the backlight unit according to an embodiment of the invention. The reflection layer in these figures or any other figures can be applied to any backlight unit of the invention. 
     The reflection layer  240  of the backlight unit  200  according to the embodiment of the invention may have a reflectance equal to or greater than 2. For example, the reflection layer  240  may be configured to have different reflectances depending on a position where the reflection layer  240  is formed. Namely, the reflection layer  240  may include at least two areas each having a different reflectance. 
     As shown in  FIG. 35 , the reflection layer  240  may include a first reflection layer  242  and a second reflection layer  243  that have different reflectances. The reflection layer  240  may be configured so that the first and second reflection layers  242  and  243  each having a different reflectance are alternately disposed. 
     For example, the reflectances of the first and second reflection layers  242  and  243  may be different from each other by configuring the first and second reflection layers  242  and  243  using reflection sheets formed of different materials, by adding a predetermined material to one of the first and second reflection layers  242  and  243  formed using the same reflection sheet, or by processing the surface of one of the first and second reflection layers  242  and  243  formed using the same reflection sheet. 
     In the embodiment of the invention, the first and second reflection layers  242  and  243  may be configured by one reflection sheet which is not physically separated. In this case, the first and second reflection layers  242  and  243  each having a different reflectance may be formed by forming a pattern for adjusting a reflectance of at least a portion of the reflection sheet. 
     That is, the reflectance of the reflection layer  240  may be adjusted by forming a pattern in at least one of a region of the reflection layer  240  corresponding to the first reflection layer  242  and a region of the reflection layer  240  corresponding to the second reflection layer  243 . For example, a pattern may be formed in the region corresponding to the second reflection layer  243  in the reflection layer  240  formed using one reflection sheet, thereby adjusting the reflectance of the region corresponding to the second reflection layer  243 . 
     More specifically, protruding patterns for diffusing light may be formed on top of the region of the reflection layer  240  corresponding to the second reflection layer  243 , thereby reducing the reflectance of the region corresponding to the second reflection layer  243 . In this case, a light diffusion efficiency in the region of the reflection layer  240  corresponding to the second reflection layer  243  can be improved. As a result, light emitted from the first light source  220  can be uniformly diffused to the third light source  222  adjacent to the first light source  220 . 
     Further, surface roughnesses of the first and second reflection layers  242  and  243  may be different from each other. For example, the surface roughness of the second reflection layer  243  may be greater than the surface roughness of the first reflection layer  242 , and thus the reflectance of the second reflection layer  243  may be less than the reflectance of the first reflection layer  242 . 
     The first reflection layer  242  that is adjacent to the light sources  220 ,  221 , and  222  based on the light emitting directions of the light sources  220 ,  221 , and  222  may be formed using a specular reflection sheet, and the second reflection layer  243  may be formed using a diffusion reflection sheet. 
     Incident light is reflected from the smooth surface of the specular reflection sheet, and thus an incident angle and a reflection angle of the specular reflection sheet may be equal to each other. Therefore, the first reflection layer  242  reflects light obliquely emitted from the light sources  220 ,  221 , and  222  at an angle equal to the incident angle and then travels the light toward the light source adjacent to the light sources  220 ,  221 , and  222 . 
     In the diffusion reflection sheet, incident light may be observed that the incident light is reflected and diffused at various angles because of a diffused reflection generated on a rough surface having uneven portions. Therefore, the second reflection layer  243  may allow light, which is emitted from the light sources  220 ,  221 , and  222  and then travels, to be diffused and then emitted upward. 
     In the embodiment of the invention, the second reflection layer  243  formed using the diffusion reflection sheet may be formed by processing the surface of the diffusion reflection sheet to form uneven portions or by applying or adding a diffusion reflection material, for example, titanium dioxide (TiO 2 ) with a predetermined density. 
     In this case, the reflectance of the first reflection layer  242  may be greater than the reflectance of the second reflection layer  243 . Therefore, as described above, the light emitted from the light sources  220 ,  221 , and  222  may be specularly reflected from the first reflection layer  242  at the same reflection angle and may be diffusively reflected from the second reflection layer  243  to be emitted upward. 
     As described above, the light emitted from the light sources  220 ,  221 , and  222  can effectively travel to the light source adjacent to the light sources  220 ,  221 , and  222  by forming the first reflection layer  242  adjacent to the light sources  220 ,  221 , and  222  based on the light emitting direction using a specular reflection sheet having a high reflectance. Hence, it is possible to prevent the luminance of light from being concentrated in the region adjacent to the light sources  220 ,  221 , and  222  and to prevent the luminance of light from being reduced in the region distant from the light sources  220 ,  221 , and  222 . 
     As described above, the travelling light can be effectively emitted to the display panel  100  by forming the second reflection layer  243  distant from the light sources  220 ,  221 , and  222  based on the light emitting direction using a diffusion reflection sheet having a relatively low reflectance. Hence, because a reduction in the luminance of light is compensated while allowing the light emitted from the light sources  220 ,  221 , and  222  to travel to the adjacent light source, a reduction in the luminance of light in the region distant from the light sources  220 ,  221 , and  222  can be prevented. 
     The specular reflection sheet for forming the first reflection layer  242  specularly reflects the light emitted from the light sources  220 ,  221 , and  222  and allows the specular reflected light to travel to the adjacent light source. At the same time, the specular reflection sheet upward reflects or scatters a portion of the emitted light to emit the light to the display panel  100 . 
     The diffusion reflection sheet for forming the second reflection layer  243  may be formed by processing the surface of a sheet formed of the same material as the specular reflection sheet or forming a plurality of protruding patterns on the sheet surface. 
     In the embodiment of the invention, the luminance of light in the region adjacent to the light sources  220 ,  221 , and  222  and the luminance of light in the region distant from the light sources  220 ,  221 , and  222  may be similarly adjusted. Therefore, the entire region of the backlight unit  200  can provide the light having the uniform luminance to the display panel  100 . 
     A width w 1  of the first reflection layer  242  adjacent to the light sources  220 ,  221 , and  222  based on the light emitting direction may be set to be greater than a width w 2  of the second reflection layer  243 , so that the light emitted from the light sources  220 ,  221 , and  222  travels to a formation area of the adjacent light source. However, the width w 1  of the first reflection layer  242  may be equal to or less than the width w 2  of the second reflection layer  243 . In this case, the reflectance of the first reflection layer  242  and the reflectance of the second reflection layer  243  may be adjusted so as to achieve the above-described effect. 
     As the width w 1  of the first reflection layer  242  decreases, a travelling performance of light emitted from the light sources  220 ,  221 , and  222  may be deteriorated. As a result, the luminance of light in the region distant from the light sources  220 ,  221 , and  222  may be reduced. Further, when the width w 1  of the first reflection layer  242  is much greater than the width w 2  of the second reflection layer  243 , the light may be concentrated in the region distant from the light sources  220 ,  221 , and  222 . For example, the luminance of light in a middle region between the two adjacent light sources  220  and  222  may be less than that in the region distant from the light sources  220 ,  221 , and  222 . 
     Accordingly, the width w 1  of the first reflection layer  242  may be 1.1 to 1.6 times the width w 2  of the second reflection layer  243 , so that the entire area of the backlight unit  200  can provide the light having the uniform luminance to the display panel  100  by upward emitting the light emitted from the light sources  220 ,  221 , and  222  through the effective travel of the light emitted from the light sources  220 ,  221 , and  222  to the formation area of the adjacent light source. 
     As shown in  FIG. 35 , the first light source  220  and the second light source  221  that are disposed adjacent to each other in the y-axis direction may be disposed at a position (i.e. outside a formation area of the first reflection layer  242 ) not overlapping the first reflection layer  242 . Further, the third light source  222  adjacent to the first light source  220  in the x-axis direction and the second light source  221  may be disposed inside a formation area of the second reflection layer  243 . 
     For example, holes into which the second light source  221  and the third light source  222  may be inserted may be formed in the second reflection layer  243 . Hence, the second and third light sources  221  and  222  mounted on the first layer  210  underlying the second reflection layer  243  may protrude upward through the holes of the second reflection layer  243  and emit the light in the lateral direction. 
     Since the location of the light sources  220 ,  221 , and  222  shown in  FIG. 35  is only one example out of various locations, a location relationship between the light sources  220 ,  221 , and  222  and the first and second reflection layers  242  and  243  may vary in the embodiment of the invention. 
     As shown in  FIG. 36 , the light sources  220 ,  221 , and  222  may be formed at a location overlapping boundary portions between the first and second reflection layers  242  and  243 . 
     As shown in  FIG. 37 , the light sources  220 ,  221 , and  222  may be positioned inside the formation area of the first reflection layers  242 . 
     As shown in  FIG. 38 , the light sources  220 ,  221 , and  222  may be positioned inside the formation area of the first reflection layers  242  at locations separated from the boundary portions between the first and second reflection layers  242  and  243  by a predetermined distance. 
     In the embodiment of the invention, a gradation area in which a reflectance gradually increases or decreases may be formed in the boundary portion between the first and second reflection layers  242  and  243  each having the different reflectance. For example, the reflectance of the gradation area may gradually decrease as the gradation area goes from one side thereof adjacent to the first reflection layer  242  to the other side thereof adjacent to the second reflection layer  243 . 
       FIG. 39  illustrates another structure of the reflection layer of a backlight unit according to the embodiment of the invention. 
     As shown in  FIG. 39 , the reflectance of the second reflection layer  243  may gradually increase or decrease depending on a location of the second reflection layer  243 . 
     In the embodiment of the invention, the reflectance of the second reflection layer  243  may gradually decrease toward an emitting direction (i.e., the x-axis direction) of light provided by the light source  221 . For example, the second reflection layer  243  has a maximum reflectance (for example, a reflectance similar to the reflectance of the first reflection layer  242 ) in the boundary portion between the first and second reflection layers  242  and  243 . Further, the reflectance of the second reflection layer  243  may gradually decrease as the second reflection layer  243  is separated from the first reflection layer  242  and is close to a light source  226  adjacent to the light source  221 . 
     As described above, because the reflectance of the second reflection layer  243  may gradually change in the boundary portion between the first and second reflection layers  242  and  243  or around the boundary portion, the luminance difference resulting from a rapid change in the reflectance of the second reflection layer  243  in the boundary portion may be reduced. 
     As described above, the second reflection layer  243  may be formed using the diffusion reflection sheet. In this case, a diffusion reflection material may be used in the second reflection layer  243 . Therefore, the reflectance of the second reflection layer  243  may gradually decrease or increase depending on the location of the second reflection layer  243  by gradually increasing or reducing a concentration of the diffusion reflection material used in the second reflection layer  243 . 
     For example, as shown in  FIG. 39 , a concentration of titanium dioxide (TiO 2 ) being the diffusion reflection material used in the second reflection layer  243  may gradually increase based on the emitting direction (i.e., the x-axis direction) of the light provided by the light source  221 . Hence, the reflectance of the second reflection layer  243  may gradually decrease. 
       FIG. 40  illustrates another structure of the reflection layer of a backlight unit according to the embodiment of the invention. 
     As shown in  FIG. 40 , the second reflection layer  243  may include a first reflection part  244  and a second reflection part  248  each having a different reflectance. A plurality of first reflection parts  244 ,  245 ,  246 , and  247  and a plurality of second reflection parts  248  may be alternately disposed. 
     In this case, widths g 1 , g 2 , g 3 , and g 4  of the first reflection parts  244 ,  245 ,  246 , and  247  of the second reflection layer  243  may gradually increase based on the emitting direction (i.e., the x-axis direction) of the light provided by the light source  221 . 
     Reflectances of the first reflection parts  244 ,  245 ,  246 , and  247  may be less than a reflectance of the second reflection part  248 , and the reflectance of the second reflection part  248  may be equal to the reflectance of the first reflection layer  242 . For this, the first reflection layer  242  and the second reflection part  248  of the second reflection layer  243  may be formed using the specular reflection sheet, and the first reflection parts  244 ,  245 ,  246 , and  247  of the second reflection layer  243  may be formed using the diffusion reflection sheet. Therefore, an average reflectance of the second reflection layer  243  may be less than the reflectance of the first reflection layer  242 . As a result, the entire area of the backlight unit  200  may provide the light having the uniform luminance to the display panel  100 . 
     As shown in  FIG. 40 , when the widths g 1 , g 2 , g 3 , and g 4  of the first reflection parts  244 ,  245 ,  246 , and  247  respectively have gradually increasing values in the order named, e.g., in the order in which the first reflection parts  244 ,  245 ,  246 , and  247  are separated from the light source  221  toward the light emitting direction (i.e., the x-axis direction), the reflectance of the second reflection layer  243  may gradually decrease. As a result, the reflectance of the second reflection layer  243  may gradually change in the boundary portion between the first and second reflection layers  242  and  243  or around the boundary portion, and thus the luminance difference resulting from a rapid change in the reflectance of the second reflection layer  243  in the boundary portion may be reduced. 
     In the above description, the embodiment of the invention has been described using the case in which the first reflection layer  242  has the uniform reflectance and the reflectance of the second reflection layer  243  varies depending on its location with reference to  FIGS. 35 to 40 , but the embodiment of the invention is not limited thereto. 
     For example, the second reflection layer  243  may have the uniform reflectance, and the reflectance of the first reflection layer  242  may vary depending on its location. Hence, the reflectance of the first reflection layer  242  may gradually change in the boundary portion between the first and second reflection layers  242  and  243 . Further, the reflectance of each of the first and second reflection layers  242  and  243  may vary depending on their location. 
       FIG. 41  illustrates another structure of the reflection layer of a backlight unit according to the embodiment of the invention. 
     As shown in  FIG. 41 , a plurality of reflection parts  244 ,  245 , and  246  may be formed in a portion adjacent to the second reflection layer  243  in a formation area of the first reflection layer  242 . The reflection parts  244 ,  245 , and  246  may extend toward the emitting direction (i.e., the x-axis direction) of the light provided by the light source  221 . Sizes, shapes, reflectances, formation materials of the reflection parts  244 ,  245 , and  246  may be different from one another. 
     The reflectances of the reflection parts  244 ,  245 , and  246  may be less than the reflectance of the first reflection layer  242  and may be equal to the reflectance of the Second reflection layer  243 . For example, the reflection parts  244 ,  245 , and  246  and the second reflection layer  243  may be formed using the diffusion reflection sheet. 
     Since the location of the light sources  221  and  226  shown in  FIGS. 39 to 41  is only one example out of various locations, the location of the light sources  221  and  226  may vary in the embodiment of the invention with reference to  FIGS. 35 to 38 . 
       FIGS. 42 and 43  illustrate a seventh exemplary configuration of a backlight unit according to the exemplary embodiment of the invention.  FIGS. 44 to 47  illustrate a structure of a reflection layer of the backlight unit according to the seventh exemplary configuration.  FIGS. 48 to 57  may be considered enlarged diagrams of an area R shown in  FIG. 43 . In these figures, the arrows indicate a general light emitting direction of the light source, e.g., a general direction in which the light from a light emitting surface of the light source is emitted, but as understood by one skilled in the art, the light from the light source may emit not necessarily in a single line but through an area. The backlight unit or light sources of these figures can additional include any one or more features (e.g., the pattern  232 , etc.) provided in the above embodiments. Further, the light sources in these figure can include the configurations of the light sources discussed in the above embodiments.  FIGS. 43 to 56A  show top plan views of backlight units and/or light source device; however, the lead electrodes (e.g.,  328 ,  329 , etc.) are generally not visible from the top, but are illustrated in these figures to provide relations between various components therein. Further, although the light sources (e.g.,  220 ) have a more rectangular shape, they may have a different shape such that the side(s) of the light source are curved or integrated or may form varying angles (e.g., an angle formed by two adjacent sides may be greater than or less than a right angle). For instance, the light source  220  may have an oval or more round shape than a rectangular shape as shown in  FIG. 42 , and/or a light emitting surface  220  may be round (concave or convex shape). Also, the light emitting surface  220  may have one or more lenses for an enhanced propagation of light. Structures and components identical or equivalent to those described in the first to sixth exemplary configurations may be designated with the same reference numerals in the seventh exemplary configuration, and a further description may be briefly made or may be entirely omitted. 
     As shown in  FIGS. 42 and 43 , the backlight unit (e.g., backlight unit  200 ) according to the seventh exemplary configuration may include the first layer  210 , the plurality of light sources  220 , the second layer  230 , and the reflection layer  240 . 
     More specifically, the plurality of light sources  220  each having a light emitting surface may be positioned on the first layer  210 . The second layer  230  may be positioned on the entire surface of the first layer  210  and may cover at least a portion of each of the plurality of light sources  220  on the first layer  210 . Alternatively, the second layer  230  may cover the entire surface of each of the plurality of light sources  220  on the first layer  210 , e.g., the second layer  230  may encapsulate the light sources  220  on the first layer  210 . The reflection layer  240  may be positioned between the first layer  210  and the second layer  230  to reflect light emitted from the light source  220 . 
     The plurality of light sources  220  on the first layer  210  may be configured so that the light sources  220  emitting light in one direction and the light sources  220  emitting light in another direction may be alternately disposed (e.g., in different lines). 
     The reflection layer  240  may include a plurality of holes  241 . These holes allow predefined gaps to be provided between the surface of the reflection layer and the outer surface of the light source  220  so as to improve the performance of the backlight unit. Because the plurality of light sources  220  and the reflection layer  240  are positioned on the first layer  210 , the plurality of light sources  220  and the reflection layer  240  may be positioned on the same plane. 
     Because the plurality of holes  241  of the reflection layer  240  are positioned on the first layer  210  on which the plurality of light sources  220  and the reflection layer  240  are positioned, the plurality of holes  241  may allow the light sources  220  to protrude from an upper part of the reflection layer  240 . In other words, because a height of each light source  220  may be greater than a height of the reflection layer  240 , light emitted from the light sources  220  may be reflected from the reflection layer  240  and may be widely diffused. 
     In the embodiment of the invention, the reflection layer  240  may be separated from one surface of at least one of the plurality of light sources  220 . 
     Each of the light sources  220  may have a light emitting surface  220   a  emitting light, a back surface  220   b  opposite the light emitting surface  220   a , a bottom surface  220   c  opposite the first layer  210 , and a side surface  220   d  preferably perpendicular to the light emitting surface  220   a  and the bottom surface  220   c . The first and second lead electrodes  328  and  329  illustrated in  FIG. 28  may be positioned on the bottom surface  220   c  of each light source  220 . 
     More specifically, as shown in  FIGS. 42 and 43 , side surfaces of the first and second lead electrodes  328  and  329  on the bottom surface  220   c  of the light source  220  may be positioned on the same line as the back surface  2206  of the light source  220 . An inner surface of the hole  241  of the reflection layer  240  may be positioned to be separated from the back surface  220   b  and the side surface  220   d  of the light source  220  on which the first and second lead electrodes  328  and  329  are positioned. Thus, a generation of a circuit short which may result from a contact between the reflection layer  240  formed of a conductive material and the first and second lead electrodes  328  and  329  may be prevented. 
     As shown in  FIGS. 44 to 47 , the reflection layer  240  of the backlight unit  200  according to the seventh exemplary configuration may include a first reflection layer  242  and a second reflection layer  243  each having a different reflectance in the same manner as  FIGS. 35 to 38 . However, the reflection layer of the backlight unit of  FIGS. 42-58  may have the configurations of the reflection layer discussed in any other figures/embodiments. The reflection layer  240  may be configured so that the first and second reflection layers  242  and  243  having the different reflectances are alternately disposed. 
     As shown in  FIG. 44 , the light sources  220  positioned adjacent to one another in the x-axis and y-axis directions may be positioned in non-overlapping areas (i.e., formation areas of the second reflection layers  243 ) between the light sources  220  and the first reflection layers  242 . For example, each second reflection layer  243  may have the plurality of holes  241  into which the light sources  220  are inserted. At least one inner surface of each hole  241  may be separated from at least one surface of each light source  220  so that certain gaps between the side(s) of the light sources and the side(s) of the reflection layer are provided. 
     As shown in  FIG. 45 , the light sources  220  may be positioned at locations overlapping boundary portions between the first and second reflection layers  242  and  243 . In this case, at least one inner surface of each hole  241  defined by the reflection layer  240  may be separated from at least one surface of each light source  220  so as form predefined gaps therebetween. 
     As shown in  FIG. 46 , the light sources  220  may be positioned in a formation area of the first reflection layers  242 . In this case, at least one inner surface of each hole  241  may be separated from at least one surface of each light source  220 . 
     As shown in  FIG. 47 , the light sources  220  may be positioned in the formation area of the first reflection layers  242  at locations separated from the boundary portions between the first and second reflection layers  242  and  243  by a predetermined distance. In this case, at least one inner surface of each hole  241  may be separated from at least one surface of each light source  220 . 
       FIGS. 44 to 47  illustrate that the first and second lead electrodes of the light sources  220  are positioned at one side of each light source  220 . As variations, the first and second lead electrodes may be positioned at various locations. A relationship between the holes  241  of the reflective layer  240  and on a location of the first and second lead electrodes of the light sources  220  is below described in detail. 
     As shown in  FIG. 48  enlarging an area R shown in  FIG. 43 , the light source  220  may be positioned on the first layer  210 , and the reflection layer  240  may be formed on the same plane as the light source  220  on the first layer  210  and may have the hole  241  for protruding the light source  220 . The hole  241  of the reflection layer  240  may be positioned to surround the light source  220 , and a portion of an inner surface of the hole  241  may be separated from at least one (outer) surface of the light source  220  so that a predetermined gap or space is formed therebetween, e.g., for avoiding short circuits. 
     As described above, the light source  220  may have the light emitting surface  220   a  emitting light, the back surface  220   b  opposite the light emitting surface  220   a , and the side surface  220   d  generally perpendicular to the light emitting surface  220   a  and the bottom surface  220   e , but may not have all these surfaces. The first and second lead electrodes  328  and  329  may be positioned on or near the bottom surface  220   c  of the light source  220 , but can be positioned at any other locations. 
     As shown in  FIG. 48 , one side surface of each of the first and second lead electrodes  328  and  329  of the light source  220  may be positioned on the same line as the back surface  220   b  and the side surface  220   d  of the light source  220 . 
     The inner surface of the hole  241  of the reflection layer  240  may be positioned to be separated from the back surface  220   b  and the side surface  220   d  of the light source  220  on which the first and second lead electrodes  328  and  329  are positioned. Further, the inner surface of the hole  241  of the reflection layer  240  may contact the light emitting surface  220   a  of the light source  220  on which the first and second lead electrodes  328  and  329  are not positioned. 
     When the reflection layer  240  formed of, e.g., metal or metal oxide is physically or electrically separated from the first and second lead electrodes  328  and  329  of the light source  220 , an electric current does not flow between the reflection layer  240  and the first and second lead electrodes  328  and  329 . Hence, a malfunction (e.g., short circuit) of the light source  220  is prevented. Accordingly, because the inner surface of the hole  241  of the reflection layer  240  is positioned to be separated from the back surface  220   b  and the side surface  220   d  of the light source  220  in the embodiment of the invention, a defect such as the malfunction of the light source  220  is prevented. 
     A separated distance (gap distance or gap length) d 5  between the light source  220  and the inner surface of the hole  241  of the reflection layer  240  may be uniform, and may be from 0.1 mm to 1 mm. When the separated distance d 5  is equal to or greater than 0.1 mm, an electric current may not flow between the first and second lead electrodes  328  and  329  on one surface of the light source  220  and the reflection layer  240 . Hence, the malfunction of the light source  220  may be prevented. Further, when the separated distance d 5  is equal to or less than 1 mm (but equal to or greater than 0.1 mm), a reduction of a light reflection effect may be prevented. More specifically, light emitted from other light source  220  positioned in a direction of the back surface  220   b  of the light source  220  has to be reflected from the reflection layer  240 . However, because the reflection layer  240  does not exist in a space (corresponding to the separated distance d 5 ) between the light source  220  and the inner surface of the hole  241  of the reflection layer  240 , a reflection effect of the light emitted from the other light source  220  may be reduced. However, in the embodiment of the invention, the reduction of the light reflection effect may be prevented because the distance d 5  of the gap has been properly predefined to be equal to or less than 1 mm. 
     As shown in  FIG. 49 , the first and second lead electrodes  328  and  329  of the light source  220  may be positioned on or near the bottom surface of the light source  220 , and one side surface of each of the first and second lead electrodes  328  and  329  of the light source  220  may be positioned on the same line as the light emitting surface  220   a  and the side surface  220   d  of the light source  220 . The inner surface of the hole  241  of the reflection layer  240  may be positioned to be separated from the light emitting surface  220   a  and the side surface  220   d  of the light source  220  on which the first and second lead electrodes  328  and  329  are positioned. Further, the inner surface of the hole  241  of the reflection layer  240  may contact the back surface  220   b  of the light source  220  on which the first and second lead electrodes  328  and  329  are not positioned. For instance, the light sources  220  are positioned within the holes  241  such that the predefined gaps (having a distance such as d 5  of  FIG. 48 ) are formed at three sides of the light source  220  between the surfaces of the reflection layer  240  and the light emitting surface  220   a  and two side surfaces  220   d  of the light source  220 . 
     As shown in  FIG. 50 , the first and second lead electrodes  328  and  329  of the light source  220  may be positioned on or near the bottom surface of the light source  220 , and one side surface of each of the first and second lead electrodes  328  and  329  of the light source  220  may be positioned on the same line as the back surface  220   b  of the light source  220 . The inner surface of the hole  241  of the reflection layer  240  may be positioned to be separated from the back surface  220   b  of the light source  220  on which the first and second lead electrodes  328  and  329  are positioned, by a predefined distance (e.g., d 5 ). Further, the inner surface of the hole  241  of the reflection layer  240  may contact the light emitting surface  220   a  and the side surface  220   d  of the light source  220  on which the first and second lead electrodes  328  and  329  are not positioned. 
     As shown in  FIG. 51 , the first and second lead electrodes  328  and  329  of the light source  220  may be positioned on or near the bottom surface of the light source  220 , and one side surface of each of the first and second lead electrodes  328  and  329  of the light source  220  may be positioned on the same line as the light emitting surface  220   a  of the light source  220 . The inner surface of the hole  241  of the reflection layer  240  may be positioned to be separated from the light emitting surface  220   a  of the light source  220  on which the first and second lead electrodes  328  and  329  are positioned by a predefined distance (e.g., d 5 ). Further, the inner surface of the hole  241  of the reflection layer  240  may contact the back surface  220   b  and the side surface  220   d  of the light source  220  on which the first and second lead electrodes  328  and  329  are not positioned. 
     As shown in  FIG. 52 , the first and second lead electrodes  328  and  329  of the light source  220  may be positioned on or near the bottom surface of the light source  220 , and one side surface of each of the first and second lead electrodes  328  and  329  of the light source  220  may be positioned on the same line as the back surface  220   b  and the side surface  220   d  of the light source  220 . 
     Unlike the above description, the inner surface of the hole  241  of the reflection layer  240  may be positioned to be separated from a portion of each of the back surface  220   b  and the side surface  220   d  of the light source  220  on which the first and second lead electrodes  328  and  329  are positioned. In other words, the inner surface of the hole  241  of the reflection layer  240  may be separated from the light source  220  in only an area in which the first and second lead electrodes  328  and  329  are positioned. 
     As shown in  FIG. 53 , one side surface of each of the first and second lead electrodes  328  and  329  of the light source  220  may be positioned on the same line as the light emitting surface  220   a  and the side surface  220   d  of the light source  220 . The inner surface of the hole  241  of the reflection layer  240  may be positioned to be separated from a portion of each of the light emitting surface  220   a  and the side surface  220   d  of the light source  220  on which the first and second lead electrodes  328  and  329  are positioned. In other words, the inner surface of the hole  241  of the reflection layer  240  may be separated from the light source  220  in only an area in which the first and second lead electrodes  328  and  329  are positioned. 
     As shown in  FIGS. 54 and 55 , the inner surface of the hole  241  of the reflection layer  240  may be positioned to be separated from all the surfaces, e.g., the light emitting surface  220   a , the back surface  220   b , and the side surface  220   d  of the light source  220 , by one or more predefined distances (e.g., d 5 ). 
     In some examples above, the rectangular hole  241  of the reflection layer  240  has been described in the embodiment of the invention. Other shapes may be used for the hole  241 . For example, a polygon having sides equal to or greater than three, a circle, an oval, etc. may be used. 
     As described above, the backlight unit according to the seventh exemplary configuration can prevent the malfunction of the light sources and the reflection effect of light by forming predefined gap(s) between the surface(s) of the reflection layer and the outer surfaces of the light source or the lead electrodes of the light source. 
       FIGS. 56A and 56B  are generally top and side views and show another example of a backlight unit according to an embodiment of the invention. As shown in  FIGS. 56A and 56B , at least one light source  220  of the backlight unit may be disposed within a hole  241  defined by the reflection layer  240  formed on the first layer  210 , where the second layer  230  encapsulates the light source  220 . The light source  220  is positioned in the hole  241  such that predefined varying gaps are provided between the surface(s) of the reflection layer  240  and the outer surfaces of the light source  220 . For instance, a first predefined gap having a set distance such as d 5  mentioned above is formed between the light emitting surface  220   a  of the light source  220  and the surface of the reflection layer  240 . A second predefined gap having a set distance such as d 6  is formed between the back surface  220   b  of the light source  220  and a corresponding surface of the reflection layer  240 . Here, the distance (d 6 ) of the second predefined gap is greater than the distance (d 5 ) of the first predefined gap. Further, third and fourth predefined gaps having a set distance may be formed between the side surfaces  220   d  of the light source  220  and corresponding surfaces of the reflection layer  240 . The third and/or fourth predefined gaps preferably have the set distance of d 5 , but can have other distance such as d 6  or a distance value between d 5  and d 6 . The lead electrodes  328 ,  329  are preferably disposed on or near the back surface  220   b  of the light source, but may be disposed at other locations. 
       FIG. 57  illustrates an eighth exemplary configuration of a backlight unit according to the exemplary embodiment of the invention. 
     As shown in  FIG. 57 , the first layer  210 , the plurality of light sources  220  formed on the first layer  210 , the second layer  230  covering the plurality of light sources  220 , and the reflection layer  240  formed on the first layer  210  that are described with reference to  FIGS. 4 to 56B  may configure one optical assembly  10 . And the backlight unit  200  may be configured by disposing the above optical assembly  10  in plural. 
     The plurality of optical assemblies  10  included in the backlight unit  200  may be arranged in N by M matrix form in the x-axis and y-axis directions, where N and M are natural numbers equal to or greater than 1. 
     As shown in  FIG. 57 ,  21  optical assemblies  10  of the backlight unit  200  may be arranged in 7×3 matrix. However, since the assembly arrangement shown in  FIG. 57  is just one example for describing the backlight unit according to the embodiment of the invention, the embodiments of the invention are not limited thereto. The arrangement of the optical assemblies  10  may be changed depending on the screen size of the display device, etc. For example, in case of a 47-inch display device, the backlight unit  200  may be configured by arranging 240 optical assemblies  10  in 24×10 matrix. 
     Each of the optical assemblies  10  may be fabricated as an independent assembly, and the optical assemblies  10  may be disposed adjacent to one another to form a module-type backlight unit. The module-type backlight unit serving as backlight unit may provide light to the display panel  100 . 
     As described above, the backlight unit  200  may be driven in a full driving manner such as global dimming or a partial driving manner such as local dimming and impulsive driving. The backlight unit  200  may be driven in various driving manners depending on a circuit design. As a result, in the embodiment of the invention, a color contrast ratio can increase, and also the image quality can be improved because a bright image and a dark image may be clearly displayed on the screen of the display device. 
     In other words, the backlight unit  200  may be divided into a plurality of division driving regions to operate and such regions may be independently and selectively driven (e.g., selectively dimmed, brightened, turned off/on, etc.). More specifically, the backlight unit  200  may reduce a luminance of a dark image and increase a luminance of a bright image based on a relation between a luminance of each of the division driving regions and a luminance of a video signal, thereby improving the contrast ratio and the definition. 
     For example, the backlight unit  200  may upwardly provide light by independently driving only some of the plurality of optical assemblies  10 . For this, the light sources  220  included in the each of the optical assemblies  10  may be independently controlled. 
     An area of the display panel  100  corresponding to one optical assembly  10  may be divided into two or more blocks. The display panel  100  and the backlight unit  200  may be separately driven in block unit. 
     Because the plurality of optical assemblies  10  are assembled as described above to configure the backlight unit  200 , a manufacturing process of the backlight unit  200  may be simplified and a manufacturing loss generated in the manufacturing process may be minimized. Hence, productivity of the backlight unit  200  may be improved. Further, the optical assembly  10  according to the embodiment of the invention may be applied to the backlight unit having various sizes by standardizing the optical assembly  10  and mass-producing the standardized optical assembly  10 . 
     When one of the plurality of optical assemblies  10  of the backlight unit  200  is defective, only the defective optical assembly is replaced without replacing all of the optical assemblies  10  of the backlight unit  200 . Therefore, a replacing work is easy and the part replacing cost is saved. 
       FIG. 58  is a cross-sectional view illustrating a configuration of a display device according to the exemplary embodiment of the invention. Structures and components identical or equivalent to those illustrated in  FIGS. 1 to 57  may be designated with the same reference numerals in  FIG. 58 , and a further description may be briefly made or may be entirely omitted. 
     As shown in  FIG. 58 , the display panel  100  including the color filter substrate  110 , the TFT substrate  120 , the upper polarizing plate  130 , and the lower polarizing plate  140  may closely adhere to the backlight unit  200  including the first layer  210 , the plurality of light sources  220 , and the second layer  230 . For example, an adhesive layer  150  may be formed between the backlight unit  200  and the display panel  100  to adhesively fix the backlight unit  200  to the bottom of the display panel  100 . 
     More specifically, the top of the backlight unit  200  may adhere to the bottom of the lower polarizing plate  140  using the adhesive layer  150 . The backlight unit  200  may further include a diffuse sheet, and the diffuse sheet may closely adhere to the top of the second layer  230 . In this case, the adhesive layer  150  may be formed between the diffuse sheet of the backlight unit  200  and the lower polarizing plate  140  of the display panel  100 . 
     Further, a back plate  50  may be disposed on the bottom of the backlight unit  200  and may closely adhere to the bottom of the first layer  210 . 
     The display device may include a display module  20 , more particularly a power supply unit  55   c  for supplying a driving voltage to the display panel  100  and the backlight unit  200 . For example, the plurality of light sources  220  of the backlight unit  200  may be driven (collectively as one or selectively in separate groups) using the driving voltage received from the power supply unit  55   c  to emit light. 
     The power supply unit  55   c  may be disposed and fixed onto the back plate  50  covering a back surface of the display module  20 , so that the power supply unit  55   c  is stably supported and fixed. 
     In the embodiment of the invention, a first connector  310  may be formed on a back surface of the first layer  210 . For this, a hole for inserting the first connector  310  may be formed in the back plate  50 . 
     The first connector  310  may electrically connect the power supply unit  55   c  with the light source  220  to allow the driving voltage supplied by the power supply unit  55   c  to be supplied to the light source  220 . 
     For example, the first connector  310  may be formed on the bottom of the first layer  210  and may be connected to the power supply unit  55   c  through a first cable  420 . Hence, the first connector  310  may be used to transfer the driving voltage received from the power supply unit  55   c  through the first cable  420  to the light source  220 . 
     An electrode pattern, for example, a carbon nanotube electrode pattern may be formed on the top of the first layer  210 . The electrode formed on the top of the first layer  210  may contact the electrode formed in the light source  220  and may electrically connect the light source  220  with the first connector  410 . 
     Further, the display device may include a driving controller  55   a  for controlling a drive of the display panel  100  and the backlight unit  200 . For example, the driving controller  55   a  may be a timing controller. 
     The timing controller may control a driving timing of the display panel  100 . More specifically, the timing controller may generate a control signal for controlling a driving timing of each of a data driver, a gamma voltage generator, and a gate driver that are included in the display panel  100  and may supply the control signal to the display panel  100 . 
     The timing controller may synchronize with a drive of the display panel  100  and may supply a signal for controlling driving timing of the light sources  220  to the backlight unit  200 , so that the backlight unit  200 , more specifically, the light sources  220  operate. 
     As shown in  FIG. 58 , the driving controller  55   a  may be disposed and fixed onto the back plate  50  positioned on a back surface of the display module  20 , so that the driving controller  55   a  may be stably supported and fixed. 
     In the embodiment of the invention, a second connector  320  may be formed on the first layer  210 . For this, a hole for inserting the second connector  320  may be formed in the back plate  50 . 
     The second connector  320  may electrically connect the driving controller  55   a  with the first layer  210 , thereby allowing a control signal output from the driving controller  55   a  to be supplied to the first layer  210 . 
     For example, the second connector  320  may be formed on the bottom of the first layer  210  and may be connected to the driving controller  55   a  through a second cable  430 . Hence, the second connector  320  may be used to transfer a control signal received from the driving controller  55   a  through the second cable  430  to the first layer  210 . 
     A light source driver may be formed on the first layer  210 . The light source driver may drive the light sources  220  using the control signal(s) supplied from the driving controller  55   a  through the second connector  320 . 
     The driving controller  55   a  and the power supply unit  55   c  may be covered by the hack cover  40  and may be protected from the outside. 
     The configuration of the display device shown in  FIG. 58  is just one embodiment of the invention. Therefore, the location or the numbers of each of the driving controller  55   a , the power supply unit  55   c , the first and second connector  310  and  320 , and the first and second cables  420  and  430  may be changed, if necessary. 
     Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.