Patent ID: 7768888
Filing Date: 2010-08-03
Classification: G11B

Abstract:
1. A method of discriminating a kind of an optical disk among a plurality of different kinds of optical disks in an optical disk apparatus comprising a plurality of laser sources of different wavelengths, an actuator which moves an objective lens towards or away from a recording surface of an optical disk, a spherical aberration correction device which corrects spherical aberration using a moving mechanism, a correction position detector which detects a spherical aberration correction position of the spherical aberration correction device, and an optical detector which detects a reflected light from an optical disk, the method comprising: when the spherical aberration correction position is at a predetermined home position, using a first discrimination method in which: while the objective lens is being moved towards or away from the recording surface of an optical disk, a plurality of laser beams are sequentially irradiated onto the optical disk one after another by being switched from one laser beam to another; at the same time as the switching of the laser beams to be irradiated onto the optical disk, spherical aberration correction is made for each laser beam by the spherical aberration correction device so that the spherical aberration is corrected for each of the laser beams of the plurality of the laser sources; a reflected light from the optical disk by irradiation of each laser beam is detected; a signal is generated from the each reflected light; and using the signals, the kind of the disk is discriminated among the plurality of the optical disks; and when the spherical aberration correction position is not at the predetermined home position, using a second discrimination method in which the spherical aberration correction position is compared with predetermined positions corresponding to the respective kinds of the optical disks to discriminate the kind of the optical disk among the plurality of kinds of the optical disks.