| 摘要 |
PROBLEM TO BE SOLVED: To surely position an optical sheet in a surface lighting device without forming a tab on the optical sheet.SOLUTION: Positions of end edges 181a, 182a, and 183a of a plurality of optical sheets 18 at a light-incident surface 12c side of a light guide plate 12 are formed to be more separated from the light-incident surface 12c of the light guide plate 12 the upper a laminated step of the optical sheets is, calculated from a light-emitting surface 12a of the light guide plate 12. The end edge 181a, 182a, and 183a of each optical sheet 18 at a light-incident surface 12c side of the light guide plate 12 is exposed without being covered with the other optical sheet located at an upper step in plan view of the light-emitting surface 12a of the light guide plate 12. The vicinities of the respective end edges 181a, 182a, and 183a of the whole optical sheets 181, 182, and 183 are fixed with a light-shielding member 20, since the light-shielding member 20 extends from the light-incident surface 12c side of the light guide plate 12 to the exposed end edges 181a, 182a, and 183a of the optical sheets 18. |
