| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a plane light source device of sufficient display quality, which has a high light utilization ratio and a high uniformity of in-plane luminance, and provide a display device using the above light source device. <P>SOLUTION: The plane light source device is provided with a case 2 having an opening 1 at least on one side, an LED light source 4 supported by one side of the case 2 facing the opening 1 and a light guide plate 5 arranged in a position to cover the opening 1 and the LED light source 4. The light guide plate 5 is arranged in a position to face the LED light source 4 and has a concave part 6 to house a part of the LED light source 4 and a light volume adjusting means 7 which is provided in the bottom of the concave part 6 and adjusts light from the LED light source 4. The light volume adjusting means 7 is provided with a reflecting sheet 20 which has a reflecting function and a total light transmission ratio t to satisfy a formula of t≥πr<SP>2</SP>cosθ/ä(1-cosθ)(S-πr<SP>2</SP>)} where r is for an average radius, H for a distance from the LED light source 4, S for a light emitting area of the LED light source 4, and L for a total light volume. <P>COPYRIGHT: (C)2007,JPO&INPIT |
