Optical functional sheet

Abstract

An optical functional sheet characterized in that, at least within the sheet, a light diffusing phase and a transparent phase each extend along a direction perpendicular to the surface of the sheet and are alternately arranged along the sheet surface direction. The optical functional sheet has a smooth surface that can be surface-treated or laminated with another functional sheet and is provided with a light collecting effect due to the internal arrangements thereof that is capable of collecting both light diverging transversely and light diverging longitudinally using a single sheet. Thus, the sheet can be useful for applications such as the backlight for liquid crystal displays.

1 . An optical functional sheet comprising, at least within the sheet, light diffusing phases and transparent phases each extending in a direction perpendicular to the surface of the sheet, wherein the transparent phases continue from the front surface to the back surface through the thickness direction of the sheet, and wherein the light diffusing phases are arranged in a form of continuous phase in which the light diffusing phases are mutually coupled in the direction toward the sheet surface, and the transparent phases are arranged in a form of discontinuous phases in which the transparent phases are decoupled by the light diffusing phases.  
     
     
         2 . An optical functional sheet according to  claim 1 , wherein the shape of projective image of the transparent phase onto the sheet surface is selected from the group consisting of trigon, tetragon, hexagon, circle and ellipsoid.  
     
     
         3 . An optical functional sheet according to  claim 1 , wherein a ratio of the length L of the transparent phase in the direction along the film thickness of the sheet to the length p of the transparent phase in the direction along the sheet surface: (L/p), in any cross section of the sheet is 2-10.  
     
     
         4 . A combined optical functional sheet comprising an optical functional sheet according to  claim 1  and a light diffusive sheet comprising a transparent matrix component in which fine particulate matter having different refractive index from that of the matrix component is dispersed.  
     
     
         5 . A backlight for a liquid crystal display comprising an optical functional sheet comprising, at least within the sheet, light diffusing phases and transparent phases each extending in a direction perpendicular to the surface of the sheet, wherein the transparent phases continue from the front surface to the back surface through the thickness direction of the sheet, and wherein the light diffusing phases are mutually coupled in the direction toward the sheet surface, and the transparent phases are arranged in a form of discontinuous phases in which the transparent phases are decoupled by the light diffusing phases.  
     
     
         6 . A backlight for a liquid crystal display according to  claim 5 , further comprising a light diffusive sheet.  
     
     
         7 . A backlight for a liquid crystal display according to  claim 5 , further comprising a fluorescent tube.