Optical disk apparatus and an optical disk playback method

An optical disk apparatus adopted to play back an optical disk, comprising:

• a laser source to emit a laser beam on an optical disk;
• a condenser lens to condense a laser beam reflected by the optical disk;
• a photodetector including a first main light receiving part and a second main light receiving part, which are disposed adjacently to each other and irradiated by the condensed laser beam, a first auxiliary light receiving part disposed on a first side of the first main light receiving part, which is opposite to a second side thereof adjacent to the second main light receiving part, and a second auxiliary light receiving part disposed on a first side of the second main light receiving part, which is opposite to a second side thereof adjacent to the first main light receiving part;
• and
• a signal processor to generate a playback signal from a difference between a sum of an output of the first main light receiving part and an output of the second main light receiving part and a sum of an output of the first auxiliary light receiving part and an output of the second auxiliary light receiving part, and a focusing error signal from a difference between a sum of the output of the first main light receiving part and an output of the second auxiliary light receiving part and a sum of the second main light receiving part and an output of the second auxiliary light receiving part.

An optical disk apparatus adopted to play back an optical disk, comprising:

• a laser source to emit a laser beam to an optical disk;
• a condenser lens to condense the laser beam reflected by the optical disk;
• a photodetector including:
• a first main light receiving part and a second main light receiving part, which are disposed adjacently to each other and irradiated by the condensed laser beam,
• a first auxiliary light receiving part disposed on a first side of the first main light receiving part, which is opposite to a second side thereof adjacent to the second main light receiving part,
• a second auxiliary light receiving part disposed on a first side of the second main light receiving part, which is opposite to a second side thereof adjacent to the first main light receiving part,
• a third main light receiving part and a fourth main light receiving part, which are disposed adjacently to each other and irradiated by the condensed laser beam,
• a third auxiliary light receiving part disposed on a first side of the third main light receiving part, which is opposite to a second side thereof adjacent to the fourth main light receiving part, and
• a fourth auxiliary light receiving part disposed on a first side of the fourth main light receiving part, which is opposite to a second side thereof adjacent to the third main light receiving part;
• and
• a signal processor to generate a playback signal from a difference between a sum of an output of the first main light receiving part, an output of the second main light receiving part, an output of the third main light receiving part and an output of the fourth main light receiving part and a sum of an output of the first auxiliary light receiving part, an output of the second auxiliary light receiving part, an output of the third auxiliary light receiving part and an output of the fourth auxiliary light receiving part, and to generate a focusing error signal from a difference between a sum of the output of the first main light receiving part, the output of the second auxiliary light receiving part, the output of the third main light receiving part and the output of the fourth auxiliary light receiving part and a sum of the output of the first auxiliary light receiving part, the output of the second main light receiving part, the output of the third auxiliary light receiving part and the output of the fourth main light receiving part.

An optical disk playback method of playing back an optical disk, comprising:

• preparing a photodetector having a main light receiveing part and an auxiliary light receiving part disposed adjacently to the main light receiving part;
• emitting a laser beam to an optical disk;
• condensing the laser beam reflected by the optical disk with a condenser lens;
• emitting the reflected laser beam condensed by the condenser lens to the photodetector;
• and
• outputting a difference between an output of the main light receiving part and an output of the auxiliary light receiving part, which are produced by emitting the reflected laser beam to the photodetector, as a playback signal representing information recorded on an information recording layer of the optical disk.

An optical disk playback method of playing back an optical disk, the method comprising:

• preparing a photodetector having a first main light receiving part and a second main light receiving part, which are disposed adjacently to each other, a first auxiliary light receiving part disposed on a first side of the first main light receiving part, which is opposite to a second side thereof adjacent to the second main light receiving part, and a second auxiliary light receiving part disposed on a first side of the second main light receiving part, which is opposite to a second side thereof adjacent to the first main light receiving part;
• emitting a laser beam to an optical disk,
• condensing the laser beam reflected by the optical disk,
• emitting the condensed reflected laser beam to the first main light receiving part, the second main light receiving part, the first auxiliary light receiving part and the second auxiliary light receiving part;
• generating a playback signal from a difference between a sum of an output of the first main light receiving part and an output of the second main light receiving part and a sum of an output of the first auxiliary light receiving part and an output of the second auxiliary light receiving part;
• and
• generating a focusing error signal from a difference between a sum of the output of the first main light receiving part and the output of the second auxiliary light receiving part and a sum of the output of the second main light receiving part and the output of the second auxiliary light receiving part.

An optical disk playback method of playing back an optical disk, comprising:

• preparing a photodetector having a first main light receiving part and a second main light receiving part which are disposed adjacently to each other, a first auxiliary light receiving part disposed on a first side of the first main light receiving part, which is opposite to a second side thereof adjacent to the second main light receiving part, a second auxiliary light receiving part disposed on a first side of the second main light receiving part, which is opposite to a second side thereof adjacent to the first main light receiving part, a third main light receiving part and a fourth main light receiving part which are disposed adjacently to each other and irradiated by the condensed laser beam, a third auxiliary light receiving part disposed on a first side of the third main light receiving part, which is opposite to a second side thereof adjacent to the fourth main light receiving part, and a fourth auxiliary light receiving part disposed on a first side of the fourth main light receiving part, which is opposite to a second side thereof adjacent to the third main light receiving part;
• emitting a laser beam to an optical disk;
• condensing the laser beam reflected by the optical disk;
• emitting the condensed reflected laser beam to the first main light receiving part, the second main light receiving part, the first auxiliary light receiving part, the second auxiliary light receiving part, the third main light receiving part, the fourth main light receiving part, the third auxiliary light receiving part, and the fourth auxiliary light receiving part;
• generating a playback signal from a difference between a sum of outputs of the first main light receiving part, the second main light receiving part, the third main light receiving part and the fourth main light receiving part, and a sum of outputs of the first auxiliary light receiving part, the second auxiliary light receiving part, the third auxiliary light receiving part and the fourth auxiliary light receiving part;
• and
• generating a focusing error signal from a difference between a sum of outputs of the first main light receiving part, the second auxiliary light receiving part, the third main light receiving part and the fourth auxiliary light receiving part and a sum of outputs of the first auxiliary light receiving part, the second main light receiving part, the third auxiliary light receiving part and the fourth main light receiving part.