Optical disc apparatus and tracking control method and program for the optical disc apparatus

摘要

An optical disc apparatus for performing tracking control based on TE and OFT signals even with such low-quality optical discs that do not meet the standards on track-to-track distance. A signal generating unit generates a TE signal and also generates an OFT signal from an input RF signal based on a first threshold value. A duty ratio calculating unit calculates a duty ratio, a ratio of the H signals to the OFT signal in length, by measuring the time of the H signals in the OFT signal. A threshold value changing unit changes the threshold value from the first value to the second value if the duty ratio does not fall within a predetermined range. A tracking control unit controls the driving unit in accordance with the TE signal and the OFT signal when the duty ratio falls within the predetermined range.