| 摘要 |
PROBLEM TO BE SOLVED: To provide a surface light source device capable of restraining reduction of luminance on four corners of an illumination zone serving as an illumination target, in spite of a structure where a plurality of LEDs 12 are arranged in a zone smaller than the size of a bottom plate 11a so as to make arrangement density lower at a peripheral section Rp rather than a center section Rc.SOLUTION: A backlight 3 serving as a surface light source device includes the plurality of LEDs 12, and the bottom plate 11a having a mounting surface 11a. The plurality of LEDs 12 are two-dimensionally arranged in a rectangular zone RA smaller than the size of the bottom plate 11a on the mounting surface 11a. Further, the arrangement density of the LEDs 12 in the rectangular zone RA is low in the peripheral section Rp rather than the center section Rc. The rectangular zone RA has corner regions where at least one LED 12 is arranged on each corner. The LED 12 located on each corner region is arranged so as to make its center axis fall down to an outer peripheral side of the rectangular zone RA from a direction perpendicular to the mounting surface 11a. |
