| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a surface light source device capable of sufficiently uniformly dispersing light from a spot-shaped light source, and to provide a light control plate unit and a transmission type image display apparatus. <P>SOLUTION: A surface light source device 21A includes four light control plates 30<SB POS="POST">1</SB>to 30<SB POS="POST">4</SB>provided in a plate thickness direction. Each light control plate has a plurality of convex portions 33<SB POS="POST">1</SB>to 33<SB POS="POST">4</SB>on the upper surface thereof, respectively. The extension direction of the convex portions 33<SB POS="POST">1</SB>and 33<SB POS="POST">2</SB>in parallel with each other is substantially perpendicular to the extension direction of the convex portions 33<SB POS="POST">3</SB>and 33<SB POS="POST">4</SB>in parallel with each other. The cross-sectional shapes of the convex portions 33<SB POS="POST">2</SB>and 33<SB POS="POST">4</SB>are triangles. In each of the convex portions 33<SB POS="POST">1</SB>and 33<SB POS="POST">3</SB>, a contour shape v(u) in an uv coordinate system with an axis line passing through both ends in a cross section perpendicular to the extension direction as a u axis satisfies 0.95v<SB POS="POST">0</SB>(u)≤v(u)≤1.05v<SB POS="POST">0</SB>(u). The v<SB POS="POST">0</SB>(u) satisfies the following expression (1). <P>COPYRIGHT: (C)2012,JPO&INPIT |
