Liquid crystal display device having uniform brightness

A liquid crystal display device comprising:

• a liquid crystal panel,
• a backlight assembly comprising an optical plate, and
• a plurality of light-emitting diode (LED) light sources,
• wherein the optical plate has a first surface substantially parallel to a bottom surface of the liquid crystal panel, and
• wherein the optical plate includes a height-varying portion formed on a second surface opposite the first surface and extending fully in a first direction between a first lateral surface and a second lateral surface of the optical plate, and a triangular prism pattern formed along the height-varying portion and extending in the first direction,
• wherein the plurality of LED light sources are arranged at a predetermined pitch in a second direction perpendicular to the first direction and facing a disposed directly on the first lateral surface of the optical plate,
• wherein at least one of the plurality of LED light sources is disposed facing thinner portions of the height-varying portion, and
• wherein the predetermined pitch corresponds to a distance measured between adjacent thinner portions of the height-varying portion.