Patent ID: 8228448

Claim:
A backlight module, comprising: a beam splitting film, comprising: a light transmissive substrate, having a first surface and a second surface opposite to the first surface, wherein the first surface is a light emitting surface; and a plurality of strip-shaped protrusion structures, disposed on the second surface, wherein each of the strip-shaped protrusion structures has a first inclined surface group and a second inclined surface group, the first inclined surface group and the second inclined surface group are inclined to the first surface, an inclining direction of the first inclined surface group relative to the first surface is opposite to an inclining direction of the second inclined surface group relative to the first surface, the first inclined surface group comprises a first inclined surface and a second inclined surface, a slope of the first inclined surface relative to the first surface is different to a slope of the second inclined surface relative to the first surface, the second inclined surface group comprises a third inclined surface and a fourth inclined surface, and a slope of the third inclined surface relative to the first surface is different to a slope of the fourth inclined surface relative to the first surface; a light guide plate, disposed at a side of the beam splitting film, wherein the light guide plate has a third surface, a fourth surface opposite to the third surface, and two light incident surfaces connecting the third surface and the fourth surface, the two light incident surfaces are respectively located at two opposite sides of the light guide plate, the third surface is located between the second surface and the fourth surface, and the second surface is located between the first surface and the third surface; and two light emitting elements, respectively disposed beside the two light incident surfaces, and capable of respectively emitting two light beams, wherein the two light beams are capable of respectively entering the light guide plate through the two light incident surfaces and being transmitted to the beam splitting film through the third surface, and the two light emitting elements are capable of alternately flickering.