| 摘要 |
<P>PROBLEM TO BE SOLVED: To effectively use reflection light by increasing a light receiving area. <P>SOLUTION: Incremental light receiving elements 140L and 140R are disposed so as to be divided across a light source 130 in a circumferential direction of a rotation disc 110, and first and second absolute light receiving elements 150D and 150U are disposed on both of the outer side and the inner side in a radial direction of the rotation disc 110 to the light source 130. Therefore, the incremental light receiving elements 140L and 140R and the absolute light receiving elements 150D and 150U can be disposed so as to surround the periphery of the light source 130 from four directions, while continuously disposing first and second absolute light receiving elements 151 and 152. <P>COPYRIGHT: (C)2012,JPO&INPIT |
