| 摘要 |
PROBLEM TO BE SOLVED: To improve measurement accuracy of a displacement.SOLUTION: An encoder 10 calculates signals sinA-sinD and signals cosA-cosD corresponding to sensor arrays 26A-26D, by setting the sensor arrays 26C, 26D to the sensor arrays 26A, 26B for two periods of an interference pattern and applying difference processing to signals a-h obtained from light receiving elements 28a-28h. An output signal selection unit 38 outputs waveform signals SinQ, CosQ having high signal levels and small noise, by selecting a signal having a high signal level as the waveform signal SinQ from among the signals sinA-sinD and selecting a signal having a high signal level as the waveform signal CosQ from among the signals cosA-cosD, on the basis of phase information of the interference pattern and absolute values of the signals. |
