| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an encoder capable of improving detection accuracy, and to provide an optical module and a servo system. <P>SOLUTION: An encoder comprises slit arrays SA1 and SA2 with a plurality of reflection slits arranged along a measurement axis, and an optical module 130 facing a part of the slit arrays and relatively movable on the measurement axis C. The optical module has: a point light source 131 for emitting light to the slit arrays; and light-receiving arrays PA1 and PA2 disposed at a position offset to the point light source in a direction of a width R perpendicular to the measurement axis in an in-plane parallel to the slit arrays and arranging a plurality of photo detectors for receiving reflected light emitted from the point light source and reflected at the reflection slits, respectively, along the measurement axis. The plurality of photo detectors have shapes with shorter length in a width direction, respectively, as the photo detectors are closer to the point light source in a measurement axis direction, and are arranged so that an end part En on the side opposite to the point light source in a width direction is at a position along the measurement axis. <P>COPYRIGHT: (C)2012,JPO&INPIT |
