Patent ID: 7933373

Claim:
A phase correction circuit of an encoder signal in a position detector, the position detector having: an analog to digital (AD) converter for generating an A 1 signal and a B 1 signal by converting sinusoidal signals of an A phase and a B phase having a phase difference of 90 degrees into digital data; a peak detector for detecting peak values of the A 1 signal and the B 1 signal; an offset/amplitude correction section for generating an A 2 signal and a B 2 signal by correcting offsets and an amplitude error using the peak values detected by the peak detector; and a position data conversion section for converting the sinusoidal signals of the A phase and the B phase into position data, the phase correction circuit comprising: a phase error detector for detecting an intersection value of the A 2 signal and the B 2 signal; and a phase correction section for computing a correction factor of the A 2 signal and the B 2 signal from the intersection value detected by the phase error detector, wherein the phase correction section generates an A correction signal and a B correction signal by multiplying the A 2 signal and the B 2 signal by the correction factor and corrects phase errors of the A phase and the B phase by adding the B correction signal to the A 2 signal and adding the A correction signal to the B 2 signal.