Patent ID: 7717600

Claim:
A backlight unit for a liquid crystal display device, comprising: at least two straight type light emitting lamps for generating light, wherein a first of the straight type light emitting lamps is arranged at one side of the light guide plate, and another a second of the straight type light emitting lamps is arranged at another side of the light guide plate and is perpendicular to one side of the light guide plate, wherein one of the two straight type light emitting lamps is operated or the two straight type light emitting lamps are simultaneously operated; a light guide plate for converting linear light generated from the straight type light emitting lamps into planar light and irradiating the light onto an LCD panel, wherein the light guide plate is divided into first, second, third, and fourth regions, the area of the first and third regions being the same size and the area of the second and fourth areas being the same size; a plurality of optical patterns formed on the light guide plate, wherein the optical patterns comprises large and small optical patterns, and have different sizes for uniformly applying light incident onto the LCD panel to the entire LCD panel, wherein the large optical patterns nearest to the straight type light emitting lamps are arranged to have a large gap therebetween, whereas the small optical patterns farthest from the straight type light emitting lamps are arranged to have a smaller gap therebetween than that of the large optical patterns, and wherein the first region and the fourth region of the light guide plate are nearest to the straight type light emitting lamps are provided with the large optical patterns, and the third region of the light guide plate located opposite of the first region and farthest from the straight type light emitting lamps is provided with second the small optical patterns; and the second region located opposite the fourth region on the light guide plate has a mix of large optical patterns and small optical patterns, a diffusion sheet for transmitting light emitted from the light guide plate in a direction substantially perpendicular to the LCD panel.