Skew detection method and optical disc device

An optical disc device comprising:

• a pickup that simultaneously acquires a main reproduction signal, a first reproduction signal and a second reproduction signal from a main track, and a first adjacent track and a second adjacent track located on each side of the main track, respectively;
• a first filter to which the first reproduction signal acquired from the first adjacent track is supplied;
• a second filter to which the second reproduction signal acquired from the second adjacent track is supplied;
• a delay circuit to delay the main reproduction signal based on main coefficients of a main filter associated with the main track and second coefficients of the second filter;
• a first combining unit that combines a first output signal of the first filter and a second output signal of the second filter with the delayed main reproduction signal so as to cancel crosstalk;
• a coefficient control unit that determines an error based on comparison between an output signal of the first combining unit with a predetermined target value and controls first coefficients of the first filter and the second coefficients of the second filter based on the determined error;
• a skew detection unit that detects a skew of an optical disc from values of the first coefficients and the second coefficients;
• and
• a skew correction unit that corrects the detected skew.