| 摘要 |
PROBLEM TO BE SOLVED: To improve resolution, accuracy, and reliability of measurement in a dimension measurement device using an optical scale. SOLUTION: By digitizing a two-phase signal detected after passed through an optical scale, only the signal strength of an area with a high strength change ratio of the digitized signal is selectively detected for forming digitized data. In the digitized data with the high strength change ratio, a signal strength and the number of signals of digitized data for movement by one grid pitch detected in the vicinity of a movement starting position and a stopping position are compared those of digitized data for movement by less than one grid pitch, and from proportional computing of the number of digitized signals, a movement distance below one grid pitch is detected.
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