| 摘要 |
PURPOSE:To obtain sharp and quick response by simplified structure, by forming a plurality of encoded code display regions shifted in a radius direction and a circumferential direction to a code member and reading said regions through two light pervious regions. CONSTITUTION:The first light pervious member 13 is constituted by forming a spiral slit 14 being the first light pervious region to a light pervious disc and an encoder disc 15 is coaxially provided to a steering shaft 12 above the member 13. The disc 15 is rotationally driven at a rotational speed sufficiently faster than the angular displacement speed of the steering shaft 12. A large number of code display regions 17 are formed to the disc 15 in a concentrically circular manner so as to be shifted in radius and circumferential directions. Further, the second light pervious member 18 is mounted under the member 13 at a fixing position in the axial direction of the steering shaft. In the optical rotary encoder 11 thus formed, each region 17 of the disc 15 can be read at the position where the slit 14 of the member 13 communicates with the slit 19 of the member 18. By this constitution, even the slight angular displacement quantity of the shaft 12 can be detected.
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