Patent ID: 8172445

Claim:
A backlight module, comprising: a light emitting unit; a first frame located on one side of the light emitting unit and a first display window is enclosed by the first frame, wherein the first frame has a first frame surface; a second frame located on the other side of the light emitting unit opposing to the first frame and a second display window is enclosed by the second frame, wherein the display area of the second display window is larger than the display area of the first display window; and a light diffusing plate located between the first frame surface of the first frame and the light emitting unit, wherein the light diffusing plate has a smooth surface and a rough surface respectively on the two sides thereof and light is transmittable between the smooth surface and the rough surface of the light diffusing plate; wherein the rough surface of the light diffusing plate is facing the light emitting unit, and wherein the light diffusing plate defines an opening corresponding to the first display window.