Encoder output signal correction apparatus and method

摘要

An encoder output signal correction apparatus for correcting two-phase sinusoidal signals with a phase difference output from an encoder, comprising a detector means (31) operative to detect an error from an ideal Lissajous waveform contained in a Lissajous waveform obtained from said two-phase sinusoidal signals; and a corrector means (30) operative to correct said two-phase sinusoidal signals using a correction coefficient based on said error detected at said detector means (31), wherein said detector means detects an error from said ideal Lissajous waveform contained in said two-phase sinusoidal signals corrected at said corrector means, and accumulatively computes said detected error to yield a new correction coefficient, thereby dynamically updating said correction coefficient, wherein said detector means is capable of detecting a third harmonic distortion contained in said Lissajous waveform obtained from said two-phase sinusoidal signals.