ANISOTROPIC DIFFUSION PLATE AND BACKLIGHT UNIT PROVIDED WITH THE SAME

摘要

Provided is a direct-lighting backlight wherein a tube-shaped light source (fluorescent lamp or the like) cannot be visually recognized and luminance of light from a display unit is made uniform. A diffusion plate for such direct-lighting backlight is also provided. An anisotropic diffusion plate (24) which configures the direct-lighting backlight unit is arranged between a display unit (1) and a plurality of tube-shaped light sources (22) which apply light to the display unit from the back surface. The anisotropic diffusion plate is composed of an anisotropic scattering layer wherein a continuous phase (C) and a particle-like diffusion phase (D) which respectively have different refractive indexes are provided, an average aspect ratio of the particle diffusion phase (D) is larger than 1, and the long axis direction of the particle-like diffusion phase (D) is oriented in one direction. As for scattering characteristics (F(?)), which indicate relationship between a scattering angle (?) and a scattering light intensity (F), anisotropy at an diffusion angle (?) of 18° satisfies an inequality of F<SUB>18</SUB>(Fy(18°)/Fx(18°))>2, where, a light scattering characteristic in the long axis direction of the particle-like diffusion phase is expressed as Fx(?), and a scattering characteristic in the direction orthogonally intersecting with the long axis direction of the particle-like diffusion phase is expressed as Fy(?), and a haze value is 95% or more and a thickness is 0.5-5mm.