| 摘要 |
<P>PROBLEM TO BE SOLVED: To radiate illumination light having high directivity and uniform brightness distribution, while enhancing the utilization efficiency of light, in a light pipe 1 which allows a light from a light source impinging from an incident opening 5, to be repeatedly reflected on a side wall surface 3 and radiated from a radiation opening 6. <P>SOLUTION: A diffraction portion 4 is formed in a region on the side of the incident opening 5 of the sidewall surface 3 of the light pipe 1, and light is reflected in the diffraction portion 4, such that a reflection angle γ2 is larger than a reflection angle γ1, whereby a radiation angle β of light radiated from the radiation opening 6 is smaller than an incident angle α of the light which is incident from the incident opening 5. <P>COPYRIGHT: (C)2010,JPO&INPIT |
