Patent Publication Number: US-8118458-B2

Title: Optical lens, optical package having the same, backlight assembly having the same and display device having the same

Description:
CROSS-REFERENCE TO RELATED FOREIGN APPLICATION 
     This application is a divisional of U.S. application Ser. No. 11/369,424, filed on Mar. 7, 2006 now U.S. Pat. No. 7,862,221, which in turn claims priority from Korean Patent Application No. 2005-33364, filed on Apr. 22, 2005, the disclosures of both of which are herein incorporated herein by reference in their entireties. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Embodiments of the present invention relate to an optical lens, an optical package having the optical lens, a backlight assembly having the optical lens and a display device having the optical lens. More particularly, embodiments of the present invention relate to a hybrid-typed optical lens capable of covering a large screen, an optical package having the optical lens, a backlight assembly having the optical lens and a display device having the optical lens. 
     2. Description of the Related Art 
     A liquid crystal display (LCD) device, in general, displays an image using optical and electrical characteristics of liquid crystals. The LCD device is a non-emissive typed display device, which requires a light source. The LCD device displays the image using an externally provided light or an internally provided light from a light source in the LCD device. 
     An exemplary light source includes a cold cathode fluorescent lamp (CCFL), a flat fluorescent lamp (FFL), a light emitting diode (LED), etc. 
     The LED is essentially a point light source that has poor luminance uniformity. In order to increase the luminance uniformity of the LED, an optical lens covers the LED. 
     Optical lenses for covering the LED are classified into top illumination typed optical lenses and side illumination typed optical lenses. When the top illumination typed optical lens covers the LED, a luminance of the light source is increased. However, the luminance uniformity of the light source having the top illumination typed optical lens is decreased. When the side illumination typed optical lens covers the LED, the luminance uniformity of the light source is increased. However, a portion of the light generated from the LED may leak from the side illumination typed optical lens. 
     As a screen size of the LCD device is increased, the number of the light emitting diodes is increased. However, when the number of the light emitting diodes is increased, a power consumption and a manufacturing cost of the LCD device are increased. 
     In addition, size and thickness of the LCD device are also increased, as the number of the light emitting diodes is increased. 
     SUMMARY OF THE INVENTION 
     An embodiment of the present invention provides a hybrid-typed optical lens capable of covering a large screen. 
     An embodiment of the present invention also provides an optical package having the above-mentioned optical lens. 
     An embodiment of the present invention also provides a backlight assembly having the above-mentioned optical lens. 
     An embodiment of the present invention also provides a display device having the above-mentioned optical lens. 
     An optical lens in accordance with an embodiment of the present invention refracts and reflects a light to increase a luminance in a top direction of the optical lens and to decrease a luminance in a horizontal direction of the optical lens. The optical lens includes a central portion and a peripheral portion. The central portion has a convex shape. The peripheral portion has a concave shape. The peripheral portion surrounds the central portion. 
     An optical package in accordance with an embodiment of the present invention includes a light emitting member and an optical lens. The light-emitting member generates a light. The optical lens refracts and reflects the light to increase a luminance in a top direction of the optical lens and to decrease a luminance in a horizontal direction of the optical lens. The optical lens includes a central portion and a peripheral portion. The central portion has a convex shape. The peripheral portion has a concave shape. The peripheral portion surrounds the central portion. 
     A backlight assembly in accordance with an embodiment of the present invention includes a substrate, a light emitting diode, an optical lens and a reflecting plate. The light emitting diode is on the substrate to generate a light. The optical lens refracts and reflects the light to increase a luminance in a top direction of the optical lens and to decrease a luminance in a horizontal direction of the optical lens. The optical lens includes a central portion and a peripheral portion. The central portion has a convex shape. The peripheral portion has a concave shape. The peripheral portion surrounds the central portion. The reflecting plate is interposed between the light emitting diode and the optical lens to reflect a portion of the light leaked from the optical lens. 
     A display device in accordance with an embodiment of the present invention includes a display panel and a backlight assembly. The display panel displays an image using a light. The backlight assembly includes a light emitting diode and an optical lens. The light emitting diode generates a light. The optical lens refracts and reflects the light to increase a luminance in a top direction of the optical lens and to decrease a luminance in a horizontal direction of the optical lens. The optical lens includes a central portion having a convex shape, and a peripheral portion having a concave shape. 
     According to an embodiment of the present invention, the optical lens of the button type is a hybrid typed optical lens having a top illumination type and a side illumination type where the area covered by the one LED is increased. Therefore, the power consumption and a manufacturing cost of the backlight assembly are decreased, although the display device has the large screen. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing an optical lens of a button type in accordance with an embodiment of the present invention; 
         FIG. 2  is a cross-sectional view showing a light path through the optical lens shown in  FIG. 1 ; 
         FIG. 3  is a cross-sectional view showing a curvature of the optical lens shown in  FIG. 1 ; 
         FIG. 4  is a cross-sectional view showing a size of the optical lens shown in  FIG. 1 ; 
         FIGS. 5A to 5C  are images showing optical simulations of the optical lens having various thicknesses; 
         FIG. 6  is a graph showing a relationship between a light extraction and a height of a wing of the optical lens shown in  FIG. 1 ; 
         FIG. 7  is a graph showing a relationship between an orientation angle and a light extraction of the optical lens shown in  FIG. 1 ; 
         FIG. 8  is an image showing an optical simulation of the optical lens shown in  FIG. 1  when an optical system of the optical lens is about 20 mm; 
         FIG. 9  is a perspective view showing an optical lens of a bowl type in accordance with another embodiment of the present invention; 
         FIG. 10  is an image showing an optical simulation of the optical lens shown in  FIG. 9 ; 
         FIG. 11  is an image showing an optical simulation of the optical lens shown in  FIG. 1  when an optical system of the optical lens is about 40 mm; 
         FIG. 12  is a graph showing a relationship between a light extraction and a thickness of the optical lens shown in  FIG. 1 ; 
         FIG. 13  is a partial cutout perspective view showing a backlight assembly in accordance with an embodiment of the present invention; and 
         FIG. 14  is an exploded perspective view showing a display device in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
     Embodiments of the invention are described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. 
     Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
       FIG. 1  is a perspective view showing an exemplary optical lens of a button type in accordance with an embodiment of the present invention.  FIG. 2  is a cross-sectional view showing a light path through the exemplary optical lens shown in  FIG. 1 . 
     Referring to  FIGS. 1 and 2 , the optical lens  10  of the button type includes a central portion  12  and a peripheral portion  14 . A recess  16  is formed on a bottom surface of the central portion  12  to receive a light-emitting element such as a light emitting diode (LED). The recess  16  has a shape corresponding to the light-emitting element. A light generated from the light emitting element is incident into the optical lens  10  so that a central light exits from surfaces of the central portion  12  and a peripheral light exits from surfaces of the peripheral portion  14 . The light incident into the optical lens  10  is refracted and reflected where an intensity of the central light is decreased, and an intensity of the peripheral light is increased, thereby increasing a luminance uniformity. That is, the optical lens  10  increases the luminance in the top direction, and decreases the luminance in the horizontal direction. When a size of the optical lens  10  is increased, an area covered by the optical lens  10  is increased. 
     The central portion  12  has a convex shape protruded in a top direction (z-direction). The central portion  12  has a substantially circular shape when viewed on a plane (x-y plane). The central portion  12  is defined by a plurality of curved surfaces having various curvatures. For example, the central portion  12  may function as a convex lens. Contour lines of the central portion  12  may be substantially parallel with each other. Alternatively, the contour lines of the central portion  12  may be shifted toward a predetermined direction. That is, a portion of the contour lines may be denser than a remaining portion of the contour lines. 
     The peripheral portion  14  has a concave shape to receive the central portion  12 , and surrounds the central portion  12 . In particular, the peripheral portion  14  has the concave shape in the top direction (z-direction). The peripheral portion  14  may have a substantially donut shape surrounding the central portion  12  when viewed on the plane (x-y plane). The peripheral portion  14  is defined by a plurality of curved surfaces having various curvatures. The peripheral portion  14  may function as a concave lens. Contour lines of the peripheral portion  14  may be substantially parallel with each other. Alternatively, the contour lines of the peripheral portion  14  may be shifted toward a predetermined direction. That is, a portion of the contour lines may be denser than a remaining portion of the contour lines. 
     The central portion  12  may be integrally formed with the peripheral portion  14 . For example, the optical lens  10  includes a polymethylmethacrylate (PMMA) based resin. A refractive index of the PMMA based resin is about 1.5. 
     Referring again to  FIG. 2 , a first light path PATH 1  and a second light path PATH 2  are depicted in the central portion  12 . The central portion  12  guides the first and second light paths PATH 1  and PATH 2  to diffuse the light exiting from the surface of the central portion  12 . 
     In particular, a first exiting angle θ 1   t  of the first light path PATH 1  is greater than a first incident angle θ 1   i  of the first light path PATH 1 . In Snell&#39;s law, the central portion  12  has a greater refractive index than an air so that the first light path PATH 1  is refracted to diffuse the light exiting from the surface of the central portion  12 , thereby increasing the first exiting angle θ 1   t.    
     In addition, a second exiting angle θ 2   t  of the second light path PATH 2  is greater than a second incident angle θ 2   i  of the second light path PATH 2 . 
     A luminance of the light generated from a central portion of the LED is greater than that of the light generated from a peripheral portion of the LED. In order to increase the luminance uniformity, the shape of the optical lens  10  is adjusted to decrease the luminance of the light generated from the central portion of the LED, and to increase the luminance of the light generated from the peripheral portion of the LED. In  FIG. 2 , the central portion  12  has a V-shaped recess to decrease the luminance of the light generated from the central portion of the LED, and to increase the luminance of the light generated from the peripheral portion of the LED. 
     A light passing through the third light path PATH 3  is totally reflected from the concave surface of the peripheral portion  14 , and exits from a side surface of the optical lens  10 . That is, when the light is irradiated onto the concave surface of the peripheral portion  14  at a third incident angle θ 3   i , the light is then totally reflected from the concave surface of the peripheral portion  14  at a reflection angle θ 3   r  that is substantially same as the third incident angle θ 3   i . The reflected light is irradiated onto the side surface of the optical lens  10  at a fourth incident angle θ 4   i  to exit from the side surface at a fourth exiting angle θ 4   t.    
     The first and second light paths PATH 1  and PATH 2  correspond to a top emission typed optical lens. The third light path PATH 3  corresponds to a side emission typed optical lens. Therefore, the optical lens  10  of  FIGS. 1 and 2  has a hybrid typed optical lens having the top and side emission typed optical lenses. 
       FIG. 3  is a cross-sectional view showing a curvature of the exemplary optical lens shown in  FIG. 1 . 
     Referring to  FIGS. 1 to 3 , the central portion  12  has the convex shape having the recess on a center of the central portion  12 . The convex shape having the recess is defined by the curved surfaces having various curvatures. 
     For example, the central portion  12  includes a first curved surface, a second curved surface, a third curved surface, a fourth curved surface and a fifth curved surface. The first curved surface is on the center of the central portion  12 , and has a first radius of curvature of about 2.76 mm. A center of the first radius of curvature is under the first curved surface. That is, the first curved surface is protruded toward a front of the optical lens  10 . The second curved surface is adjacent to the first curved surface and connected to the first curved surface, and has a second radius of curvature of about 1.98 mm. A center of the second radius of curvature is under the second curved surface. The third curved surface is adjacent to the second curved surface and connected to the second curved surface, and has a third radius of curvature of about 2.15 mm. A center of the third radius of curvature is under the third curved surface. The fourth curved surface is adjacent to the third curved surface and connected to the third curved surface, and has a fourth radius of curvature of about 4.07 mm. A center of the fourth radius of curvature is on the fourth curved surface. That is, the fourth curvature is protruded toward a rear of the optical lens  10 . The fifth curved surface is adjacent to the fourth curved surface and connected to the fourth curved surface, and has a fifth radius of curvature of about 22.97 mm. A center of the fifth radius of curvature is on the fifth curved surface. The first, second, third, fourth and fifth curved surfaces define the convex shape having the recess. Note that the radii presented in this paragraph are exemplary and non-limiting, and other radii of curvature are within the scope of an embodiment of the invention. 
     The peripheral portion  14  includes a sixth curved surface and a seventh curved surface. The sixth curved surface is adjacent to the fifth curved surface and connected to the fifth curved surface, and has a sixth radius of curvature of about 13.74 mm. A center of the sixth radius of curvature is on the sixth curved surface. The seventh curved surface is adjacent to the sixth curved surface and connected to the sixth curved surface, and has a seventh radius of curvature of about 2.70 mm. A center of the seventh radius of curvature is on the seventh curved surface. The sixth and seventh curved surfaces define the concave shape. Note that the radii presented in this paragraph are exemplary and non-limiting, and other radii of curvature are within the scope of an embodiment of the invention. 
     In  FIGS. 1 to 3 , the recess is formed on the center of the central portion  12 . Alternatively, the recess may not be formed on the center of the central portion  12 . 
     In  FIGS. 1 to 3 , one LED corresponds to one optical lens  10 . Alternatively, a plurality of light emitting diodes may correspond to one optical lens. 
       FIG. 4  is a cross-sectional view showing an exemplary, non-limiting size of the optical lens shown in  FIG. 1 . 
     Referring to  FIG. 4 , a radius L 1  of the optical lens  10  may be about 6 mm, and a maximum height T 1  of the optical lens  10  may be about 3.6 mm. In addition, a maximum height T 2  of the central portion  12  may be about 3 mm. 
     A radius L 2  of the central portion  12  may be about 3.5 mm. A height T 3  of a boundary between the central and peripheral portions  12  and  14  may be about 2.1 mm. The height T 3  of the boundary is a minimum height of the optical lens  10 . The maximum height T 2  of the central portion  12  is smaller than the maximum height T 1  of the optical lens  10 . 
     A height of an outmost portion of the peripheral portion  14  is the maximum height T 1  of the optical lens  10 . A size of the optical lens  10  may be changed. The radius L 1  and the maximum height T 1  of the optical lens  10 , the radius L 2  and the maximum height T 2  of the central portion  12 , and the height T 3  of the boundary may be substantially proportional to each other. For example, when the size of the optical lens  10  is increased, the radius L 1  and the maximum height T 1  of the optical lens  10 , the radius L 2  and the maximum height T 2  of the central portion  12 , and the height T 3  of the boundary may also be increased. 
       FIGS. 5A to 5C  are images showing optical simulations of exemplary  211  optical lenses having various thicknesses. The maximum thickness of the optical lens shown in  FIG. 5A  is about 3.7 mm. The maximum thickness of the optical lens shown in  FIG. 5B  is about 4.1 mm. The maximum thickness of the optical lens shown in  FIG. 5C  is about 4.5 mm. 
     Referring to  FIGS. 5A to 5C , the optical lens having the maximum thickness of about 3.7 mm has a substantially same optical distribution as the optical lens having the maximum thickness of about 4.1 mm. However, when the maximum thickness of the optical lens is more than about 4.5 mm, a light extraction of a center of the optical lens is decreased, thereby decreasing a luminance on the center of the optical lens. 
       FIG. 6  is a graph showing a relationship between a light extraction and a maximum height of a central portion of the exemplary optical lens shown in  FIG. 1 . Light extractions of a top direction (z-direction) and a side direction (x-y direction) are shown in  FIG. 6 . 
     Referring to  FIG. 6 , when the maximum height of the central portion is about 3.0 mm, the light extractions in the top direction and the side direction are about 84% and about 12%, respectively, and an average light extraction of the optical lens is about 96%. When the maximum height of the central portion is about 3.55 mm, the light extractions in the top direction and the side direction are about 83.56% and about 13.61%, respectively, and an average light extraction of the optical lens is about 97.17%. 
     In  FIG. 6 , a light leakage from the optical lens is no more than about 3% so that the optical lens may be optimized to a backlight assembly. 
     When the maximum height of the central portion is about 4.5 mm, the light extractions in the top direction and the side direction are about 77.91% and about 16.2%, respectively, and an average light extraction of the optical lens is about 94.11%. 
     When the maximum height of the central portion is about 4.5 mm, the optical lens can also be used for the backlight assembly, although the light leakage from the optical lens is about 5.89% that is negligible. 
     When the maximum height of the central portion is about 3.7 mm, the light extractions are maximized. In  FIG. 6 , variations of the light extractions of the optical lens having the maximum height of the central portion of no more than about 3.7 mm may be negligible. 
       FIG. 7  is a graph showing a relationship between an orientation angle and a light extraction of the exemplary optical lens shown in  FIG. 1 . In particular, orientation angles in a top direction and a horizontal direction are shown in  FIG. 7 . 
     Referring to  FIG. 7 , the orientation angle of the optical lens in the top direction is from about −60° to about +60°. An orientation angle in the top direction of an optical lens of a bowl type is from about −50° to about +50°. Therefore, the optical lens shown in  FIG. 1  diffuses the light in a wider range than the optical lens of the bowl type. 
     The orientation angle of the optical lens in the side direction is from about −80° to about +80°. The light exiting from the optical lens in the side direction may have a substantially same luminance as the light exiting from the optical lens in the top direction corresponding to the orientation angle of about −50° or about +50°. 
     The light passes through the optical lens of the button type shown in  FIG. 1  in the top direction and the side direction so that the optical lens may be a hybrid typed optical lens. 
       FIG. 8  is an image showing an optical simulation of the exemplary optical lens shown in  FIG. 1  when an optical system of the optical lens is about 20 mm. Light extractions in the top direction and the horizontal direction are shown in  FIG. 8 . 
     Referring to  FIG. 8 , the optical lens covers an area having a radius of about 38 mm. When an optical system of the optical lens of the bowl type is about 20 mm, the optical lens of the bowl type is about 20 mm. Therefore, the radius of the region covered by the optical lens shown in  FIG. 1  is greater than that of the region covered by the optical lens of the bowl type by about 90%. 
     Hereinafter, the optical lens having the bowl shape is described. 
       FIG. 9  is a perspective view showing an optical lens of a bowl type in accordance with another embodiment of the present invention.  FIG. 10  is an image showing an optical simulation of the optical lens shown in  FIG. 9 . A distance between the optical lens of the bowl type and a light sensor is about 40 mm, and an angle for sensing the light is about 70°. 
     Referring to  FIGS. 9 and 10 , a center of the optical lens  20  of the bowl type is protruded. Reference numerals  22  and  24  represent a wing portion and a guiding portion of the optical lens  20  of the bowl type, respectively. A recess  26  is formed on the guiding portion  24  to receive an LED. 
     Referring again to  FIG. 10 , the optical lens  20  of the bowl type optically covers an area having a radius of about 42 mm. A luminance is rapidly decreased in a remaining area that is not covered by the optical lens  20  of the bowl type. In addition, a luminance of a central portion of the optical lens  20  of the bowl type is smaller than that of a peripheral portion of the optical lens  20  of the bowl type. 
       FIG. 11  is an image showing an optical simulation of the exemplary optical lens shown in  FIG. 1  when an optical system of the optical lens is about 40 mm. Luminances in the top direction and the horizontal direction are shown in  FIG. 11 . 
     Referring to  FIG. 11 , the optical lens shown in  FIG. 1  optically covers an area having a radius of about 83 mm. The area covered by the optical lens shown in FIG.  FIG. 1  is greater than the area covered by the optical lens shown in  FIG. 9  by about 97%. In addition, a radius of the optical lens shown in  FIG. 9  is about 20 mm, and a radius of the optical lens shown in  FIG. 1  is about 6 mm. That is, the area covered by the optical lens shown in  FIG. 1  is increased although the radius of the optical lens shown in  FIG. 1  is decreased. 
     Therefore, the optical lens of the button type shown in  FIG. 1  optically covers the large area so that a large screen display device may include the optical lens of the button type shown in  FIG. 1 . 
       FIG. 12  is a graph showing a relationship between a light extraction and a thickness of the optical lens shown in  FIG. 1 . 
     Referring to  FIG. 12 , a maximum height of the optical lens of the button type shown in  FIG. 1  is about 3.7 mm. When the maximum height of the optical lens is no more than about 3.7 mm, the light extraction may be negligible. That is, the maximum height of the optical lens may be changed to be no more than about 3.7 mm. 
     According to an embodiment of the invention, an optical lens of the button type is a hybrid-typed optical lens having a side illumination type and a top illumination type. That is, the light extraction and the luminance uniformity of the optical lens of the button type are increased. 
     In addition, the area covered by the optical lens of the button type is greater than the area covered by the bowl type by about 97%. The light leakage of the optical lens of the button type is substantially same as the light leakage of the optical lens of the bowl type so that the light leakage of the optical lens of the button type is negligible. 
       FIG. 13  is a partially cutout perspective view showing a backlight assembly in accordance with an embodiment of the present invention. 
     Referring to  FIG. 13 , the backlight assembly  100  includes an optical package  110 , a power supply substrate  120 , a receiving container  130 , a reflecting plate  140  and a light-mixing member  150 . The power supply substrate  120  supports the optical package  110 . The receiving container  130  supports the power supply substrate  120 . The reflecting plate  140  is interposed between the power supply substrate  120  and the optical package  110 . The light-mixing member  150  is on the optical package  110 . 
     The optical package  110  includes a light emitting diode (LED)  112  and an optical lens  114  of a button type, according to an embodiment of the invention. The optical lens  114  of the button type includes a central portion and a peripheral portion. The central portion of the optical lens  114  has a convex shape. The central and peripheral portions define a button shape. A light generated from the LED  112  is incident into the optical lens  114  so that a central light and a peripheral light exiting from surfaces of the central and peripheral portions of the optical lens  114 . The light incident into the optical lens  114  is refracted and reflected so that an intensity of the central light is decreased, and an intensity of the peripheral light is increased, thereby increasing a luminance uniformity. 
     The power supply substrate  120  supports the optical package  110  to supply the LED  112  with an electric power. 
     The receiving container  130  receives the optical package  110 , the power supply substrate  120  and the light-mixing member  150 . The receiving container  130  may include a bottom plate and a sidewall. 
     The reflecting plate  140  is interposed between the power supply substrate  120  and the optical package  110 . A portion of the light leaked from the optical lens  114  is reflected from the reflecting plate  140  toward the light-mixing member  150 . The reflecting plate  140  may be a solid plate. Alternatively, the reflecting plate  140  may be a flexible sheet. 
     The light-mixing member  150  is on the optical package  110  to increase a luminance when viewed in a top direction and a luminance uniformity. The light-mixing member  150  may include a plurality of diffusion particles. 
       FIG. 14  is an exploded perspective view showing a display device in accordance with an embodiment of the present invention. 
     Referring to  FIG. 14 , the display device includes a backlight assembly  100 , a display unit  200 , a top chassis  300 , a rear case  400  and a front case  500 . 
     The backlight assembly  100  includes a plurality of optical packages  110 , a power supply substrate  120 , a receiving container  130 , a reflecting plate, a light mixing member  150  and optical sheets  160 . The power supply substrate  120  supports the optical packages  110 . The receiving container  130  supports the power supply substrate  120 . The reflecting plate  140  is interposed between the power supply substrate  120  and the optical package  110 . The light-mixing member  150  is on the optical package  110 . The backlight assembly of  FIG. 14  is same as in  FIG. 13 . Thus, the same reference numerals will be used to refer to the same or like parts as those described in  FIG. 13  and any further explanation concerning the above elements will be omitted. 
     The optical packages  110  are on the power supply substrate  120 . For example, each of the optical packages  110  generates a white light. Alternatively, the optical packages  110  may generate a red light, a green light and a blue light, respectively, or a combination thereof. 
     A portion of the light generated from the optical packages  110  is reflected from the reflecting plate  140  toward the light mixing member  150 . 
     The light mixing member  150  is on the optical packages  110 . The light generated from the optical packages  110  and reflected from the reflecting plate  140  is mixed in an air layer on the optical packages  110  by the optical packages  110 . For example, the light mixing member  150  mixes the red, green and blue lights generated from the optical packages  110 . 
     The optical sheets  160  include a diffusion sheet  162  and a prism sheet  164 . The diffusion sheet  162  diffuses the light having passed through the optical package  110 . The prism sheet  164  increases the luminance when viewed in a top direction. The prism sheet  164  may include a brightness enhancement film (BEF), a dual brightness enhancement film (DBEF), etc. 
     The receiving container  130  includes a bottom plate  132  and a sidewall  134 . The bottom plate  132  has an opening. The sidewall  134  is protruded from sides of the bottom plate  132 . The power supply substrate  120  having the optical package  110 , the reflecting plate  140 , the light mixing member  150  and the optical sheets  160  are received on the bottom plate  132  of the receiving container  130 . 
     The display unit  200  includes a liquid crystal display (LCD) panel  210 , a data tape carrier package (TCP)  220 , a gate TCP  230  and an integrated printed circuit board (PCB)  240 . The display unit  200  may further include a plurality of data tape carrier packages and a plurality of tape carrier packages. 
     The LCD panel  210  includes an array substrate  212 , a color filter substrate  214  and a liquid crystal layer (not shown). The array substrate  212  includes a plurality of pixels. The color filter substrate  214  corresponds to the array substrate  212 . The liquid crystal layer (not shown) is interposed between the array substrate  212  and the color filter substrate  214 . 
     The data tape carrier packages  220  are attached to a source side of the array substrate  212 . The gate tape carrier packages  220  are attached to a gate side of the array substrate  212 . The data and gate tape carrier packages  220  and  230  applies a driving signal and a timing signal to the LCD panel  210  to control the LCD panel  210 . 
     One end portion of each of the data tape carrier packages  220  is attached to the source side of the array substrate  212 , and another end portion of each of the data tape carrier packages  220  is attached to the integrated PCB  240  where the LCD panel  210  is electrically connected to the integrated PCB  240  through the data tape carrier packages  220 . The gate tape carrier packages  230  are attached to the gate side of the array substrate  212  where the LCD panel  210  is electrically connected to the integrated PCB  240  through the gate tape carrier packages  230 . The integrated PCB  240  applies signals to the data and gate tape carrier packages  220  and  230  based on externally provided electric signals. 
     The data and gate tape carrier packages  220  and  230  are backwardly bent along the sidewall  194  of the receiving container  190  so that the integrated PCB  240  is on a rear surface of the bottom plate  192  of the receiving container  190 . 
     The top chassis  300  is on the LCD panel  210  to fix the LCD panel  210  to the receiving container  190 . The top chassis  300  includes an opening through which a central portion of the LCD panel  210  is exposed. The top chassis  300  is combined with the receiving container  190  to fix the display unit  200  to the receiving container  190 . 
     The backlight assembly  100 , the display unit  200  and the top chassis  300  are received in the rear case  400 . The front case  500  is on the top chassis  300 . The rear case  400  is combined with the front case  500  to complete the display device. 
     According to an embodiment of the present invention, an optical lens of the button type is a hybrid typed optical lens having a top illumination type and a side illumination type where the area covered by the one LED is increased. In addition, the central portion of the optical lens may have the convex shape including the recessed center. Therefore, the power consumption and a manufacturing cost of the backlight assembly may be decreased, although the display device has the large screen. 
     This invention has been described with reference to the exemplary embodiments. It is evident, however, that many alternative modifications and variations will be apparent to those having skill in the art in light of the foregoing description. Accordingly, embodiments of the present invention embrace all such alternative modifications and variations as fall within the spirit and scope of the appended claims.