Patent ID: 7706217

Claim:
An optical disc apparatus which detects information recorded in a rotating optical disc by using a laser beam and reproduces data, comprising: an emitting unit configured to emit a laser beam to the rotating optical disc; a divided photodetector including a first divided portion and a second divided portion disposed in a light path of the reflected beam or transmitted beam from the optical record disc, the first divided portion outputs a first photodetector signal, and the second divided portion outputs a second photodetector signal; a phase difference detector configured to produce a phase difference signal from a phase difference between the first photodetector signal and the second photodetector signal; an integrator configured to produce a integral signal from a integration of the phase difference signal detected by the phase difference detector; a tracking controller configured to perform tracking control of the emitting unit based on the integral signal outputted form the integrator; a data length detector configured to detect a data length corresponding to a pit or mark/space of an information signal obtained from the optical disc; a setting unit configured to set the data length to be detected based on the reproduction speed of the optical disc and the type of the optical disc, that a minimum average sampling frequency to be obtained will be higher than a sampling frequency required for the given optical disc; and a limiter configured to limit one or both of the first and second photodetector signals to be supplied from the divided photodetector to the phase difference detector or the phase difference signal to be supplied from the phase difference detector to the integrator when the data length detected by the data length detector is not more than the minimum data length for limiting set by the setting unit.