| 摘要 |
PURPOSE:To enhance detection accuracy without narrowing a slit interval, by a method wherein a plurality of slits are arranged so as to be positionally shifted in the direction crossing the relative moving direction of the slits and an optical sensor at a right angle and the optical sensor is provided corresponding to each slit row. CONSTITUTION:Optical sensors 11, 12 are arranged at the positions opposed to the upper and lower stage slits of a slit film 20 and consist of a combination of a light emitting element and a light receiving element to be respectively connected to amplifiers 13, 14. The slits of the slit film 20 are formed so as to be shifted by a cycle and the output voltages V1, V2 of the amplifiers 13, 14 correspond to the lengths of the opposed slits. These voltage V1, V2 are inputted to an exclusive OR circuit 15; only when one of the voltages V1, V2 is an H-level, output voltage V3 is generated from the circuit 15 and becomes a position detection signal.
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