| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an angle detector capable of properly detecting a rotation angle even if decentering occurs between a scale center Og of a scale plate and a rotation center Or. <P>SOLUTION: An angle detector comprises a disk-shaped scale plate 11 formed with a plurality of scale marks 13 extending in a radial direction and a detector 12 for detecting the scale marks 13, and detects a rotation angle of the scale plate by referring to a detection signal Sd output from the detector 12 with the rotation of the scale plate 11. The angle detector comprises correcting means 20 for correcting an error of the rotation angle on the basis of eccentricity δ of a scale center Og of the scale plate 11 and a rotation center Or. The correcting means 20 includes: an eccentricity obtaining portion 21 for obtaining the eccentricity δ; a modulation index calculating portion 22 for calculating a modulation index when a detection frequency of the scale marks 13 is made to be a carrying frequency and a rotation frequency of the scale plate 11 is made to be a modulation frequency, on the basis of the eccentricity δ obtained by the eccentricity obtaining portion 21; and a high-oder component calculating portion 23 for calculating high-oder components of the modulation frequency on the basis of the modulation index calculated by the modulation index calculating portion 22. <P>COPYRIGHT: (C)2012,JPO&INPIT |
