Displacement detecting apparatus

摘要

A displacement detecting apparatus outputs a displacement information signal obtained by interpolating a phase modulation. A direction block obtains a direction signal indicative whether the cycle of the phase modulation signal is longer than the cycle of the reference signal. A phase difference block obtains the number of the interpolation clock pulses which number corresponds to a phase difference between the phase modulation signal and the reference signal. An up/down counter counts to an interpolation number upon receiving the direction signal and a pulse train corresponding to the phase difference. The presetting block presets the number of pulses corresponding to the phase difference in the up/down counter. The displacement information block outputs a Glay code converted from continuous 2 bits of the count value of the up/down counter as displacement information.