Optical film having multi-story and multi-peak prisms

Abstract

An optical film comprises: a transparent supporting layer, and a plurality of multi-story prisms having multiple peaks formed thereon and juxtapositionally integrally formed on the supporting layer, each peak of the prism tapered or narrowed upwardly towards a light output direction for increasing a light concentrating effect of the prism in order to increase the brightness of the optical film.

I claims: 
     
         1 . An optical film comprising:
 a transparent supporting layer;   a basic prism integrally formed on said supporting layer and having two basic dihedral faces of said basic prism tapered upwardly from said supporting layer to define a first apex angle between the two basic dihedral faces and to form a first apex or peak on a top of said basic prism as convergently intersected by the two basic dihedral faces; and   at least a parasitic prism integrally formed on said basic prism and having two parasitic dihedral faces of said parasitic prism tapered upwardly from one face of said two basic dihedral faces of said basic prism to define a second apex angle between said two parasitic dihedral faces and to form a second apex or peak on a top of said parasitic prism to be juxtapositioned to said first apex of said basic prism for forming multiple peaks above an upper or top portion of said basic prism for increasing a light concentrating effect.   
     
     
         2 . An optical film according to  claim 1 , wherein each said peak of said prism is formed as a round peak. 
     
     
         3 . An optical film according to  claim 1 , wherein each said face of said dihedral faces of the prism is selected from a flat face and a curved face. 
     
     
         4 . An optical film according to  claim 1 , wherein said prisms include at least a peak which is the tallest among the multiple peaks of said prisms. 
     
     
         5 . An optical film according to  claim 1 , wherein one said parasitic prism includes said two parasitic dihedral faces tapered upwardly respectively from said apex of said basic prism and from one face of said two basic dihedral faces of said basic prism. 
     
     
         6 . An optical film according to  claim 1 , wherein said parasitic prism is tapered and narrowed upwardly towards a light output direction. 
     
     
         7 . A process for making the optical film as set forth in  claim 1  by integrally forming, molding or printing at least one said parasitic prism on said basic prism integrally formed on said supporting layer.