1. Field of the Invention
The present invention relates to a backlight assembly used for an LCD (liquid crystal display) apparatus, and more particularly, to a backlight assembly improved in preventing a bright-line occurring on a front area adjacent to a light-entering surface of a light guide plate and in enhancing the brightness.
2. Description of the Related Art
Generally, an LCD apparatus comprises an LCD panel to display a picture thereon, a backlight assembly to uniformly lighten the LCD panel, and a supporting frame and a chassis to support and accommodate the LCD panel and the backlight assembly.
The LCD panel comprises a TFT (thin film transistor) array substrate formed with switching elements, pixel electrodes, etc., a color filter substrate, and a liquid crystal disposed between the TFT array substrate and the color filter substrate. A video signal is transmitted to transistors of the TFT array substrate via a source PCB (printed circuit board) and a gate PCB. Therefore, the liquid crystal receives an electric current owing to the video signal and displays a picture with the light transmitted through the backlight assembly.
The LCD panel separately needs a light source because it cannot emit light by itself, and therefore the backlight assembly is employed for lightening the LCD panel. The backlight assembly is classified into an edge type and a direct-down type according to location of a lamp.
In the case of the edge type in which the lamp is installed at lateral edges of the light guide plate, the uniformity of the light is high, the life span of the LCD apparatus can be relatively long, and the LCD apparatus can be more slimly manufactured. Further, the edge type backlight assembly is mainly applied to a relatively small LCD apparatus such as monitors of a laptop computer, a desktop computer, etc.
As shown in FIGS. 1 and 2, the conventional backlight assembly 100 comprises a light guide plate 110 converting the light into a surface light source, a lamp unit 120 emitting the light toward the light guide plate 110, a reflector 130 disposed in the rear of the light guide plate 110 and reflecting back the light from the light guide plate 110 into the light guide plate 110, and an optical sheet layer 150 placed in front of the light guide plate 110.
The light guide plate 110 includes a light-entering surface 112 through which the light from the lamp unit 120 enters, and a light-emitting surface 114 through which the light is emitted toward the optical sheet layer 150. On the light guide plate 110 facing the reflector 130 is formed a plurality of prism teeth 110a at intervals of a predetermined pitch, so that the light reflecting from the inside of the light guide plate 110 is uniformly emitted toward the LCD panel (not shown), thereby enhancing the brightness of the LCD apparatus.
The optical sheet layer 150 is placed in front of the light-emitting surface 114 of the light guide plate 110, and includes a reverse prism sheet formed with a plurality of a reverse prism teeth 150a at intervals of a predetermined pitch on the surface facing the light-emitting surface 114. The reverse prism sheet is employed in increasing vertical components of the light emitted toward the LCD panel, thereby enhancing the front brightness of the LCD apparatus.
The lamp unit 120 comprises a lamp 122 facing the light-entering surface 112 of the light guide plate 110 and emitting the light, and a lamp reflector 124 having an opening toward the light-entering surface 122 of the light guide plate 110 and combined to the light guide plate 110, accommodating and covering the lamp 122. The lamp reflector 124 reflects back the light from the lamp 122 into the light guide plate 110.
However, in the conventional backlight assembly 100, there is a problem that a bright-line “A” (refer to FIG. 1) occurs on a front area adjacent to a light-entering surface 112 of the light guide plate 110 because diffusion of the light entering through an edge 118 at which the light-entering surface 112 and the light-emitting surface 114 of the light guide plate 110 are intersected is greater than the diffusion of the light entering through the light-entering surface 112.