Patent ID: 8425103

Claim:
A backlight module for a flat panel display, comprising: a light guide plate including a first surface and a second surface opposite to each other, wherein the first surface has a plurality of prismatic structures disposed side by side thereon, each of the prismatic structures includes a first slope and a second slope being adjacent to each other and each having an included angle with respect to the first surface, the included angle of the first slope and that of the second slope are substantially equivalent, the included angles are selected from an angular range substantially between 14 degrees and 34 degrees; a brightness enhancement film including a third surface and a fourth surface opposite to each other, wherein the third surface faces the second surface of the light guide plate, the fourth surface has a plurality of prisms disposed side by side thereon along the extending direction of the prismatic structure, the brightness enhancement film has an optimum incident angle associated with an angle of the prism, wherein the optimum incident angle is in a range substantially between 25 degrees and 35 degrees, the light entering the brightness enhancement film at the optimum incident angle will exit the brightness enhancement film with the highest energy; and at least a light source module disposed beside the light guide plate along the extending direction of the prismatic structure.