LIGHT GUIDE BOARD AND SURFACE ILLUMINANT DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a light guide board which can reduce a luminance irregularity of emitted light.SOLUTION: Tabular light guide boards 10 and 110 emitting light from a light emitting surface while making light from a light source 29 enter and leading it in a light guide direction comprise a diffraction structure layer 13 possessing diffraction structure patterns 13a-13f on the light emitting surface by being formed with unevenness. At least one of the diffraction structure patterns have a structure where an edge is elongated in the light guide direction and the unevenness is arranged alternately in a direction different from the light guide direction.