| 摘要 |
PCT No. PCT/JP83/00362 Sec. 371 Date Jun. 18, 1984 Sec. 102(e) Date Jun. 18, 1984 PCT Filed Oct. 18, 1983 PCT Pub. No. WO84/01651 PCT Pub. Date Apr. 26, 1984.An optical absolute endoder, provided with a rotary code plate and fixed plate, for detecting the angle of rotation and the position of rotation of a motor, etc. The rotary code plate has a plurality of concentric code patterns with light passage portions and light blocking portions alternately arranged and a reference pattern comprised of just a light passage portion sandwiched between adjoining code patterns and arranged concentrically with the code patterns. The fixed plate is provided with first and second code pattern slit groups arranged in the radial direction of the rotary code plate at first predetermined intervals and corresponding to the code patterns and with reference pattern light passage portions provided at positions corresponding to the reference pattern at positions separated by exactly second predetermined intervals from the center line of the code pattern light groups. By this, fluctuations in the voltage level of the reference signals due to light leakage are prevented.
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