Diffusion sheet and a backlight unit using the same

The present invention includes a plurality of convex shape having a major axis and a minor axis on one side of the sheet is formed, the longitudinal direction of the convex shape are aligned in substantially one direction, Emission intensity distribution 1 of the light beam emitted from one side of the sheet when the incident light at an incident angle of 0 ° on the other surface of the sheet about the diffusion sheet satisfying the following conditions (1) and (2). (1) The emission intensity distribution 1 of the longitudinal direction of the convex shape in a plane perpendicular, emission angle at which 50% of the intensity with respect to the emission intensity of the emission angle 0 ° is in the range of 15-25 °. (2) The emission intensity distribution 1 in the longitudinal direction parallel to the plane of the vertical and convex on the sheet surface, the exit angle at which 50% of the intensity with respect to the emission intensity of the emission angle of 0 ° 0.5-5 ° is in the range of. According to the present invention, a diffusion sheet and the brightness and uniformity to the excellent backlight unit superior to the anisotropic diffusion effect of light is provided.