| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a surface light device in which an angle of field and luminance are balanced, and an optical deflection element used in the device. <P>SOLUTION: The optical deflection element 4 has an incident surface 41 on which light is made incident and an emission surface 42 which is located opposite to the incident surface 41 and from which light emits. A plurality of prism lines are arrayed on the incident surface 41 so as to be substantially parallel to one another, each prism line being composed of a pair of substantially symmetrical prism surfaces 44 an 45. Each of each pair of prism surfaces 44 and 45 is formed from at least one circular arc in the shape of a cross-section orthogonal to the extending direction of the prism lines. The ratio of the curvature radius r of the circular arc closest to the apex of the prism lines to the array pitch P of the prism lines, r/P, is 2 to 4. <P>COPYRIGHT: (C)2012,JPO&INPIT |
