| 摘要 |
PROBLEM TO BE SOLVED: To provide a rotary encoder and a mark detector which can easily and securely capture a mark into an imaging field of view, without requiring modifications causing disadvantage (deterioration in efficiency, an increase in costs, complication in imaging system, and so forth) in the constitution of the side for detecting the mark. SOLUTION: An arc-like pattern P is provided, which is positioned on a radius near an origin mark M from the center of a rotating slit plate 1 and which is interrupted at the front and the rear of the origin mark with respect to the circumferential direction. The pattern P is taken into the imaging visual field, and the rotating slit plate 1 is rotated. When the pattern is interrupted, the rotation is stopped. COPYRIGHT: (C)2005,JPO&NCIPI
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