Patent ID: 8274556

Claim:
A backlight unit employed in a 2D/3D switchable image display device, the backlight unit comprising: a plurality of segment light sources for a left eye vision range which emit a light for a left eye vision range, and a corresponding plurality of optical sheets for the left eye vision range; and a plurality of segment light sources for a right eye vision range which emit a light for a right eye vision range, and a corresponding plurality of optical sheets for the right eye vision range; and light shield film which is arranged between each of the plurality of optical sheets for the left eye vision range and a respective one of the plurality of optical sheets for the right eye vision range, such that light passing through the plurality of optical sheets for the left eye vision range is prevented from mixing with light passing through the plurality of optical sheets for the right eye vision range, wherein the segment light sources for the left eye vision range and the segment light sources for the right eye vision range are alternately arranged to form a surface light source; and wherein in a 3D mode, the segment light sources for the left eye vision range are driven in synchronism with an image for the left eye vision range, and the segment light sources for the right eye vision range are driven in synchronism with an image for the right eye vision range; and wherein in a 2D mode, the segment light sources for the left eye vision range and the segment light sources for the right eye vision range are driven in synchronism with a 2D image.