Patent ID: 8270082

Claim:
A microstructure diffuser, having a light-entering portion and a light-emitting portion, wherein the light-entering portion receives a light beam of a light, comprising: a plurality of microstructure portions covered on the light-emitting portion, wherein the plurality of microstructure portions includes a first microstructure unit and a second microstructure unit, the first microstructure unit has a substantially trapezoid lateral cross section, the first microstructure unit has a first side surface, a second side surface, a top surface, a first pitch (P 1 ), a second pitch (P 2 ), and a height (H), the first side surface and the second side surface respectively have a first slope and a second slope, the first side surface and the second side surface are respectively located at two sides of the top surface and have a distance of the second pitch between the first side surface and the second side surface, the first side surface and the second side surface are respectively located at two sides of the light-emitting portion and have another distance of the first pitch between the first side surface and the second side surface, and the distance between the top surface and the light-emitting portion is the height; wherein the first microstructure unit satisfies the following condition, ½≦2 H /( P 1 −P 2)/2≦9/5; wherein the second microstructure unit has a curve function shape and is located at the light-emitting portion, the second microstructure unit is adjacent to the first microstructure unit, the second side surface of the first microstructure unit and the second microstructure unit forms a first low point, the second microstructure unit and the first side surface of another first microstructure unit forms a second low point, and the first low point and the second low point are located at the light-emitting portion; when the plurality of microstructure portions receive the light beam of the light source, the first side surface and the second side surface of the first microstructure unit receive the light beam of the light source to form a first optical path, the top surface of the first microstructure unit receives the light beam of the light source to form a second optical path, and the second microstructure unit receives the light beam of the light source to form a third optical path.