Patent ID: 6741533
Filing Date: 2004-05-25
Classification: G11B

Abstract:
A tracking error detecting apparatus for detecting a tracking error of an optical spot obtained by radiating light on an optical recording medium, said tracking error detecting apparatus comprising:a photo detector for receiving reflected light of the optical spot and outputting photoelectric current according to a photo acceptance quantity; a plurality of current/voltage conversion circuits for converting the photoelectric current of the photo detector into voltage signals; a plurality of signal generators for generating two signal series, phases of the two signal series changing with respect to each other according to a tracking error of the optical spot, from the voltage signals; a plurality of analog-digital converters for discretizing the two signal series to obtain first and second digital signal series; a plurality of interpolation filters for performing interpolation processing of the first and second digital signal series, respectively; a plurality of zero cross point detector circuits for respectively detecting zero cross points of the first and second digital signal series interpolated by the interpolation filters; a phase difference detector circuit for detecting a phase difference between the zero cross point of the first digital signal series and the zero cross point of the second digital signal series; and a low-pass filter for performing band restriction toward the detected phase difference to obtain a tracking error signal.