Patent ID: 8475032

Claim:
A backlight device comprising: a light guide plate; and LED boards which are arranged facing end surfaces of side surface portions of the light guide plate and on which LEDs introducing light to the light guide plate are mounted, wherein lengths of long sides of the LED boards arranged on long sides facing end surfaces in a long side direction of the light guide plate are the same, and lengths of long sides of the LED boards arranged on short sides facing end surfaces in a short side direction of the light guide plate are the same, and the LED boards are arranged along the end surfaces of each of 4 sides of the light guide plate, the LED boards are alternately arranged to be misaligned on the long sides facing the end surfaces in a long side direction of the light guide plate such as not to overlap with respect to an axis of the long side direction of the light guide plate, and the LED boards are alternately arranged to be misaligned on the short sides facing the end surfaces in the short side direction of the light guide plate such as not to overlap with respect to an axis of the short side direction of the light guide plate.