| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a surface light source device having a high illuminating efficiency by a simple constitution. <P>SOLUTION: In the surface light source device including a light guide body 21 having at least one light incident face 21a and a light emitting face 21b, a light source 22 to supply light to the light incident face, and a light reflector 27 to reflect the light emitted from a face 21c opposed to a light emitting face of the light guide body, a plurality of protrusions 29 with nearly identical shape are installed in a prescribed pattern at the face 21c opposed to the light emitting face of the light guide body, a base unit 28 of a nearly identical or analogous cross-sectional shape having a slanted light reflecting face is arranged and formed by a pitch of 200 μm or less on the surface of the light reflector, and when light incident from a light incident face of the light guide body is emitted from the light emitting face 21b and the face 21c opposed to the light emitting face, an emitting direction selection rate which expresses the rate of light emitted from a face opposed to the light emitting face is 70 to 100%, and when the main advancing direction of the light incident from the incident face is taken as the direction A, and the height of the protrusion 29 as H, the average pitch between the adjacent protrusions regarding the direction A is within the range of 2.5 H to 5.0 H. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
