Patent ID: 7342864

Claim:
An optical disk reproduction apparatus comprising: a wobble signal reading unit configured to read a signal corresponding to a wobble formed at a predetermined track from an optical disk on which address information is recorded by applying phase modulation to the wobble formed at the track; an address information reproducing unit configured to reproduce the address information by applying phase detecting processing to the wobble signal read at the wobble signal reading unit, and by binarizing an amplitude of an obtained phase detection signal by being compared with a predetermined threshold value; a correcting unit configured to correct asymmetry of the amplitude generated in the phase detection signal obtained at the address information reproducing unit with respect to the predetermined threshold value at the time of reading the wobble signal from the predetermined track by the wobble signal reading unit; the correcting unit includes an offset detecting unit configured to calculate an asymmetric amount of the amplitude of the phase detection signal obtained at the address information reproducing unit, and an offset compensating unit configured to compensate the asymmetry of the amplitude of the phase detection signal based on the asymmetric amount calculated at the offset detecting unit; and the offset detecting unit includes a polarity detecting unit configured to detect positive and negative polarities of the phase detection signal obtained at the address information reproducing unit, a first maintaining unit configured to maintain the amplitude of the phase detection signal in a state in which a positive polarity of the phase detection signal has been detected by the polarity detecting unit, a first filter configured to eliminate a high frequency component from an output signal of the first maintaining unit, a second maintaining unit configured to maintain the amplitude of the phase detection signal in a state in which a negative polarity of the phase detection signal has been detected by the polarity detecting unit, a second filter configured to eliminate a high frequency component from an output signal of the second maintaining unit, and an adding unit configured to calculate an asymmetric amount of the amplitude of the phase detection signal by adding an output signal of the first filter and an output signal of the second filter.