| 摘要 |
An absolute sensor 1 has a high speed side encoder 13 mounted on a high speed rotational shaft 6, a low speed rotational shaft 11 arranged coaxially with the high speed rotational shaft 6, a planetary gear mechanism 10 for reducing the speed of rotation of the high speed rotational shaft 6 and delivering the rotation of reduced speed to the low speed rotational shaft 11. The planetary gear mechanism 10 has a fixed sun internal gear a, a front stage planetary gear b, a rear stage planetary gear c, and an output sun internal gear d connected to the rear stage planetary gear c and low speed rotational shaft 11, wherein the planetary gears b and c are rotatably supported by an eccentric shaft portion 23 of the shaft 6. The planetary gear mechanism 10 can be constituted so that the input and output shafts are arranged coaxially, and can be made small with having a large reduction ratio in comparison with the conventional reduction mechanism comprised by spur gears. Further, since the value of the reduction ratio is set a power of two, the output signals of the encoders can easily by processed by a computer system.
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