Encoder

An encoder comprising:

• a scale having a pattern to be detected corresponding to graduations;
• a detecting sensor detecting the pattern to be detected of the scale and outputting a detection signal corresponding to the detected pattern to be detected;
• and
• a position calculator calculating a relative positional relation between the scale and the detecting sensor at predetermined sampling intervals based on the detection signal output from the detecting sensor,
• the encoder further comprising:
• a position data storage storing therein position data calculated by the position calculator;
• and
• a position estimator estimating relative position data between the scale and the detecting sensor at a calculation-target time point based on the position data stored in the position data storage and outputting the estimated position data,
• the calculation-target time point being a time point later by a predetermined time than a time point when the position estimator executes estimation,
• the position estimator being configured to calculate position data at a first time point and position data at a second time point and estimate the position data at the calculation-target time point based on the calculated position data at the first time point and the calculated position data at the second time point, the first time point and the second time point each preceding the calculation-target time point by a predetermined time, and
• the position estimator being further configured to, by referring to the position data stored in the position data storage, process, by means of a digital filter, position data calculated by the position calculator during a predetermined first time width centered on the first time point to thereby calculate the position data at the first time point as a representative value in the first time width, and configured to, by referring to the position data stored in the position data storage, process, by means of the digital filter, position data calculated by the position calculator during a predetermined second time width centered on the second time point to thereby calculate the position data at the second time point as a representative value in the second time width.