| 摘要 |
PROBLEM TO BE SOLVED: To provide a planar lighting device effectively utilizing a light emitted from a point light source for saving electric power by eliminating brightness irregularity in the longitudinal direction of a rod light guide giving a light from the side end face of a plate light guide to its inside. SOLUTION: The planar lighting device 1 comprises the rod light guide 7 provided with its side face 13 opposed to a side end face 3 of the plate light guide 2 and a point light source 9 provided on an end face 8 of the rod light guide 7, wherein a light injected from the point light source 9 into the rod light guide 7 is injected into the side end face 3 of the plate light guide 2 with a light path changed by light path changing means 11 formed on the rod light guide 7 to permit the emission of light from the surface 5 of the plate light guide. The light path changing means 11 consists of a number of groove portions 15 continuously provided on the opposite side of the face of the rod light guide 7 opposite to the side end face 3 of the plate light guide 2. The opposed faces 17 (the light reflecting surfaces) of the groove portions 15 are set at such an inclination as to maximize the quantity of a light emitted from the vertical direction to positions on the opposed faces 17 corresponding to the side end face of the plate light guide. |
