PLANE ILLUMINATION DEVICE

摘要

PROBLEM TO BE SOLVED: To achieve high luminance by a simple and low cost construction. SOLUTION: A plurality of protrusions (22) are formed on the emitting face (12b) of a light-guiding plate (12) and a semi-spherical face (22a) is formed on the outer face of each protrusion (22). The light reflected at the semi- spherical face (22a) and the light transmitted the semi-spherical face (22a) are turned in the prescribed direction regularly, therefore, scattering of lights does not happen. And since the light emitted from the semi-spherical face (22a) has directivity of inclining to a prescribed angle to the emitting face (12b), almost all the lights that are irradiated to the lens sheet (20) can be modified in the direction crossing the emitting face (12b) at right angles. Thereby, high luminance is achieved as well as it is condensed by the lens sheets (20).