Abstract: A displacement detecting apparatus includes a scale having a graduation of predetermined pitches, a sensor which is displaceable with respect to the scale and detects a period signal corresponding to the pitch. Interpolating sections interpolate the periodic signal from the sensor by different resolutions. One of the interpolating sections outputs a first interpolation signal of m (positive integer) phases shifted by a phase difference .theta.1, and the other interpolating sections outputs a second interpolation signal of n (positive integer) phases shifted by a phase difference .theta.2.

Abstract: 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.

Abstract: In apparatus and method for measuring a displacement of an object to be measured, a magnitude of the displacement is derived on the basis of a difference in periods of a phase modulated signal and a reference signal, a ratio between the periods of a basic clock and of an interpolation clock which is varied according to the magnitude of the displacement, a clock signal whose period is a multiplication of a period of the basic clock by the ratio as a multiplier, a pulse train signal is created whose number of pulses are given by the magnitude of the displacement and supplied to an A/B phase converter.