Abstract: Plural diffusion patterns are formed on a light-incident surface of an optical film, while plural prisms are formed on a light-emitting surface. The diffusion patterns have, in at least one section thereof, a main inclined surface that is curved face with a relatively small inclination and an auxiliary inclined surface that is oppositely inclined to the main inclined surface with a relatively large inclination.

Abstract: In a front light equipped with a light source and a transparent plate emitting light from a light emitting surface which is situated at the reverse side against an observation side surface by conducting light from the light source, the reflection preventive patterns comprising the minute unevennesses 30 for prevention of reflection are formed on the light emitting surface. When a wavelength of visible light with the shortest wavelength among light which is emitted from the light source 24 is ?min, the refractive index of the transparent plate is n1 and the refractive index of air is n0, the period p of the minute unevennesses 30 satisfies the following equation. p<?min/(n0+n1). Thereby, it can be prevented that the diffracted light is emitted from the reflection preventive patterns (light emitting surface) of the transparent plate.

Abstract: According to a front light comprising an optical waveguide 25 and a light source 24 arranged on the side of the optical waveguide 25, the optical waveguide 25 comprises a light input surface and light emission surface 28, and a plurality of deflection patterns 26 are formed on the surface opposed to the light emission surface 28. Light from the light source 24 is input from the light input surface of the optical waveguide 25 and propagated in the optical waveguide 25. The light totally reflected by the deflection patterns 26 among the light propagated in the optical waveguide 25 is emitted from the light emission surface 28 in the direction oblique to the normal direction of the light emission surface 28. The light is emitted from the light emission surface 28 so as to be aligned in one direction regardless of its position.

Abstract: The present invention provides an optical film having a diffusion pattern that can diffuse light and direct at least a part of incident light vertically to the surface of the optical film. Further, the present invention provides an optical film having both a function of a prism sheet and a function of a diffusion sheet.