Patent ID: 6375336
Filing Date: 2002-04-23
Classification: G02B

Abstract:
A front light type spread illumination apparatus of a side-light system, in which, nearby a first side of a transparent substrate made of a material having a light permeability, a bar-like (linear) light source is provided and a light reflection pattern is formed on the transparent substrate so as to equalize a volume of emitted light spread on a screen, the light reflection pattern comprises a plurality of grooves formed along the bar-like light source and plane portions adjacent to such grooves, where the grooves are set at an angle of inclination to emit the light running through the grooves in a direction perpendicular to the back of the transparent substrate and, a length from a groove to an adjacent groove is set as a pitch, and a ratio of a width of a groove to the pitch is to be 0.01-0.15.