| 摘要 |
PROBLEM TO BE SOLVED: To reduce installation space that is occupied around a rotor in which absolute rotary angle is detected. SOLUTION: In a rotary plate 11, an annular detection region 13 where a plurality of detection holes 14a-14i, comprising detection units 13a dividing a detection region 13 into 28 portions with an equal angle are formed, is provided only along one circumference. Code data are recorded at the detection region 13 by the six detection units 13a that continue in the counterclockwise direction. A computer 15 reads code data, corresponding to the absolute rotational angle of the rotary plate 11 at that time from a detection value corresponding to the six continuous detection units 13a, that are successively detected by each of photosensors 12a-12d, while the rotary plate 11 rotates for one of the equivalent angles of the detection units 13a. Then, the absolute rotational angle of a rotary shaft S is detected from the code data.
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