Patent ID: 7529048

Claim:
An optical film comprising: a supporting layer; and a structured-surface layer formed on the supporting layer including a plurality of prisms juxtapositionally formed on the supporting layer; each said prism including: a lower prism element integrally formed with the supporting layer and at least an upper prism element integrally superimposed on said lower prism element to obtain a total height of the upper and lower prism elements to be taller than a height of the lower prism element for enhancing brightness of the optical film; said structured-surface layer having a first group of said prisms formed as triple-story prisms; each of said triple-story prisms includes said lower prism element integrally formed with the supporting layer, said upper prism element integrally superimposed on said lower prism element and a second uppermost prism element integrally superimposed on said upper prism element; and having a second group of said prisms each formed as double-story prisms to be shorter than each of said triple story prisms, wherein each of said double story prisms includes said lower prism element integrally formed with the supporting layer and said upper prism element integrally superimposed on said lower prism element.