A flat panel display can include a transparent substrate, a light emitting device formed on a surface of the transparent substrate, and a prism sheet formed on the other surface of the transparent substrate and having a plurality of polygonal protruding members having lengthwise axes parallel to one another to direct light output from the light emitting device in a predetermined direction. The sum of the thickness of the transparent substrate and the thickness of a portion of the prism sheet excluding the polygonal protruding members can be about 0.1 to about 0.5 mm.