Position/speed detection method and apparatus

Disclosed is a position detecting method and apparatus which are suitable for detecting the position of a moving body on the basis of the output of a position detector (1) for generating two-phase periodic waves having a phase difference of a quarter period, the apparatus comprising wave processing means (2) comparing either one of the two-phase periodic waves with a predetermined reference value having hysteresis to thereby obtain a roughly estimated position for every half period of the one periodic wave; means (12, 14) for analog-­to-digital converting the two-phase periodic waves and a zero-­cross value for every sampling period to thereby obtain a finely estimated position; and detecting the position of the moving body on the basis of the roughly estimated position and the finely estimated position while correcting an error due to the hysteresis at the starting point of the roughly estimated position, by use of the relationship between the roughly estimated position and the finely estimated position. Accord­ing to this method and apparatus, continuity between the roughly estimated position and the finely estimated position can be maintained, so that exact and high-resolution position detection can be performed.