Optical disk apparatus and photodetection signal processing method

An optical disk apparatus comprising:

• an optical pickup which irradiates an optical disk with a laser beam, and which has a light-reception unit including a first light-reception element and a second light-reception element, the light-reception unit receiving the laser beam reflected from the optical disk to provide a first photodetection signal and a second photodetection signal corresponding to the reflected laser beam;
• measuring units which receive the first and second photodetection signals from the optical pickup to measure propagation delay time difference between the first and second photodetection signals;
• a delay unit which delays the first and second photodetection signals based on the signal propagation delay time difference such that delay times of the first and second photodetection signals are equalized to each other;
• a characteristics determining unit which determines transmission frequency characteristics of transmission paths of the first and second photodetection signals from the first and second photodetection signals delayed by the delay unit;
• variable equalizers which change frequency transmission characteristics according to the transmission characteristics determined by the characteristics determining unit, and correct the first and second photodetection signals delayed by the delay unit;
• and
• a signal processing circuit which extracts binarized data which is reproduction information from the first and second photodetection signals corrected by the variable equalizers.

A method of processing a photodetection signal in an optical disk apparatus, the method comprising:

• irradiating an optical disk with a laser beam to receive the laser beam reflected from the optical disk with a light-reception unit including a first light-reception element and a second light-reception element, and providing a first photodetection signal and a second photodetection signal which correspond to the reflected laser beam;
• receiving the first and second photodetection signals to measure propagation delay time difference between the first and second photodetection signals;
• delaying the first and second photodetection signals based on the signal propagation delay time difference such that delay times of the first and second photodetection signals are equalized to each other;
• and
• processing the delayed first and second photodetection signals to provide the processed signals.

A method of processing a photodetection signal in an optical disk apparatus, the method comprising:

• irradiating an optical disk with a laser beam to receive the laser beam reflected from the optical disk with a light-reception unit including a first light-reception element and a second light-reception element, and providing a first photodetection signal and a second photodetection signal which correspond to the reflected laser beam;
• receiving the first and second photodetection signals to measure propagation delay time difference between the first and second photodetection signals;
• delaying the first and second photodetection signals based on the signal propagation delay time difference such that delay times of the first and second photodetection signals are equalized to each other;
• determining transmission frequency characteristics of transmission paths of the first and second photodetection signals from the delayed first and second photodetection signals;
• changing frequency transmission characteristics of variable equalizers according to the determined transmission frequency characteristics;
• correcting the delayed first and second photodetection signals with the variable equalizers;
• and
• extracting binarized data which is reproduction information from the first and second photodetection signals corrected by the variable equalizers.