Patent ID: 8596852

Claim:
A backlight unit for a liquid crystal display disposed below a liquid crystal panel to irradiate light thereto, comprising: a plurality of separate light guide plates defining respective blocks; groups of light emitting diodes each disposed along an edge of each of the light guide plates, each group of the light emitting diodes emitting light toward a corresponding one of the light guide plates; and bar-shaped printed circuit boards disposed only along the respective edges of the light guide plates, wherein each of the light guide plates has one edge with a light incidence surface perpendicular to an incidence direction of light emitted from each group of the light emitting diodes, and another edge with a cutout having a round face or an angled face, each group of the light emitting diodes is disposed at an interface between adjacent blocks, except for an outermost block, to emit light toward one of the blocks and is located below light guiding plates of other blocks adjacent to the one of the blocks, each group of the light emitting diodes is arranged on each of the bar-shaped printed circuit boards, each of the groups of the light emitting diodes is configured to be independently driven, by the bar-shaped printed circuit boards, so that one group of the light emitting diodes disposed along one of the light guide plate blocks is turned on, while other groups of the light emitting diodes disposed along other light guiding plate blocks are turned off, or the groups of the light emitting diodes are turned on with different brightness according to the corresponding light guiding plate blocks, wherein the bar-shaped printed circuit boards are not disposed in a central region of each of the light guide plates, wherein the liquid crystal panel has a plurality of divided areas, and the light emitting diodes have brightness adjusted according to the blocks, by a peak value of a grey level in each of the divided areas, and wherein the light emitting diode groups are time-synchronized with the liquid crystal panel and turned on sequentially.