Patent ID: 8457914

Claim:
An apparatus configured to correct multi-phase signals for detecting a position of an object and to obtain a phase corresponding to the position of the object, the apparatus comprising: a correcting unit configured to correct the multi-phase signals with error coefficients, respectively; a phase calculating unit configured to perform calculation for the corrected multi-phase signals to obtain the phase; a regression unit configured to perform regression for the calculated phases using a regression expression to obtain reference phases; a Fourier transform unit configured to respectively perform Fourier transform for the corrected multi-phase signals whose phases having been respectively changed into the reference phases; and an updating unit configured to update, using Fourier coefficients obtained by the Fourier transform unit, the error coefficients respectively corresponding to the Fourier coefficients, wherein the updating unit is configured to update the error coefficients if a regression error in the regression performed by the regression unit satisfies a predetermined condition.