Patent ID: 7839735

Claim:
A reproduction apparatus for performing at least reproduction for an optical disk recording medium, comprising: a head section including an objective lens configured to act as an output end of laser light to the optical disk recording medium and an input end of reflected light from the optical disk recording medium, a detector including at least two detection elements and configured to detect the reflected light obtained through said objective lens, and a tracking mechanism configured to hold said objective lens for movement at least in a tracking direction; a waveform equalization section configured to input first and second signals produced based on detection signals of said detection elements of said head section as a target waveform and an input waveform, respectively, such that a phase difference occurs when a laser spot based on the laser light is displaced from the center position of a track on the optical disk recording medium, to perform a waveform equalization process using a FIR filter so that the input waveguide may coincide with the target waveform; a phase difference detection section configured to perform a predetermined calculation based on predetermined tap coefficients of said FIR filter in said waveform equalization section to calculate an asymmetric component of the tap coefficients of said FIR filter thereby to detect a phase difference between the first and second signals; and a tracking controlling section configured to control said tracking mechanism based on the asymmetric component calculated by said phase difference detection section.