| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a position detection device that computes an absolute position by a vernier computation from a period signal different in a plurality of pitches, and does not perform a wrong detection even if dust or scratch is present on a track.SOLUTION: A position detection device comprises: a scale that has a plurality of pattern strings different in a period in a movement direction; position signal acquisition means for acquiring a plurality of signals on the basis of a position in the movement direction with respect to the scale; absolute position computation means for computing an absolute position with respect to the scale of the position signal of the position signal acquisition means on the basis of the plurality of acquired signals; wrong detection determination means for determining whether the computed absolute position is wrongly detected; storage means for storing wrong detection information including information calculated when it is determined that the absolute position is wrongly detected and information for determining whether the computed absolute position is correct; and absolute position determination means for determining whether the absolute position computed by the absolute position computation means is correct on the basis of the wrong detection information stored in the storage means.</p> |
