Patent ID: 8643259

Claim:
An optical sheet comprising: a transparent substrate having a first surface S 1 and a second surface S 2 ; a first light diffusion layer provided on a first surface S 1 side of the transparent substrate; and a second light diffusion layer provided on a second surface S 2 side of the transparent substrate, wherein the first light diffusion layer has a first surface D 1 and a second surface D 2 , and the first surface D 1 is a surface being opposite to the transparent substrate and is a smooth surface, a haze x 1 (%) of the first light diffusion layer and a haze x 2 (%) of the second light diffusion layer satisfy the following expressions (1) and (2): f ( x 1)/( f ( x 1)+ f ( x 2))≦2/3 expression (1) ( f ( x 1)+ f ( x 2))≦12 expression (2) (where when x≦88, a function f(x)=1.9×(ln(1−x/90)) 2 , and when x>88, the function f(x)=22.5x−1952.5), and total light transmittance if the optical sheet is 50% or more.