| 摘要 |
PROBLEM TO BE SOLVED: To extend the service life of a light projection element of a rotary encoder. SOLUTION: Rotary slits rs arranged on the optical paths between the light projection element LED and a plurality of light receiving elements PD1-PD4 are rotated synchronously with a shaft to be detected, the projection light of the light projection element LED is made to pass both the slits, and light signals of A phase, B phase, -A phase, and -B phase shifted by 90°in electric angle. The light signals can be received by respective light receiving elements and the total of the received light quantities of the light receiving elements to the light signals of respective phases is made constant during both rotation and rotation stop of the rotary slits, and the light projection intensity of the light projection element can be controlled by a controlling means CPU so that the total of the received light quantities of the respective light receiving elements is constant. COPYRIGHT: (C)2009,JPO&INPIT
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