As the information society is developed, demands for the display devices have been increased in a variety of forms. To meet the demands, recently, various display devices such as liquid crystal display (LCD) devices, plasma display panel (PDP) devices, electroluminescent display (ELD) devices, vacuum fluorescent display (VFD) devices, or the like have been studied and used.
The liquid crystal panel of the LCD device thereof includes a liquid crystal layer, and a thin film transistor (TFT) substrate and a color filter substrate, which are facing each other by interposition of the liquid crystal layer. Since the liquid crystal panel of the LCD device is not self-emissive, the liquid crystal panel of the LCD device may display an image using light provided from a backlight unit.
The conventional backlight unit using an isotropic lens has a structure in which light sources are orthogonally arranged or arranged in a beehive structure, and the lens spreads light emitted from the light sources in an isotropic light distribution. In the above-described structure, since a pitch between the light sources increases as the number of the light sources decreases, there is a disadvantage that it is difficult to spread away the light in an isotropic light distribution of a circular shape using a secondary lens.