LIGHT DIFFUSION FILM, SURFACE ILLUMINANT DEVICE AND LIQUID CRYSTAL DISPLAY DEVICE

摘要

A transmitting display device (21) comprises a liquid crystal display unit (22) and a surface illuminant unit (23). The surface illuminant unit comprises a tubular light source (24), a light guide member (25) having a wedge-shaped reflection groove formed at the lower portion thereof, and a light diffusion film (27) having anisotropic and/or ultraviolet absorbing properties. The light diffusion film satisfies Fy(theta)/Fx(theta) >= 1.01 within a range of scattering angle theta = 4-30 °, where Fx(theta) is a scattering characteristic in the X-axis direction of the film, and Fy(theta)a scattering characteristic in the Y-axis direction when a scattering characteristic F(theta) gives the relation between a scattering angle theta and a scattering light intensity F. The light diffusion film comprises a light diffusion layer comprised of a plurality of resins having mutually different refractive indexes, and a transparent layer laminated on at least on surface of the light diffusion layer. At least the transparent layer may contain a ultraviolet absorbing agent. Such a light diffusion film, when used, can simplify the structures of a surface illuminant device and a liquid crystal display device, and can make uniform the luminance of the display surface when the light diffusion film has an anisotropy. A light diffusion film having a ultraviolet absorbing property can absorb a ultraviolet ray from the light source (fluorescent lamp) of a surface illuminant device (back-light), and prevent the deterioration of a prism sheet and a liquid crystal display cell.