Patent ID: 8223602
Filing Date: 2012-07-17
Classification: G11B

Abstract:
1. An optical disc drive, comprising: an objective lens which focuses laser light onto a disc, a focus actuator which adjusts the position of the objective lens in the rotating axis direction of the disc, a tracking actuator which adjusts the position of the objective lens in the radial direction of the disc; an aberrations correction module which corrects spherical aberrations of the focal spot focused onto the disc by the objective lens; and a detecting module which detects information about the disc radius position of the focal spot; wherein the correction module sets an amount of spherical aberrations correction for each of a plurality of zones associated with the disc radius; wherein a change position for spherical aberrations correction is set to one of two different values depending on whether the focal spot moves from inner to outer circumference of the disc or vice versa; wherein the correction module changes the amount of spherical aberration correction to one of the two different values from the other one of the two different values when the focal spot is moving outwardly in the radial direction and exceeds a radial position PA wherein the correction module changes the amount of spherical aberration correction to the other one of the two different values from one of the two different values when the focal spot is moving inwardly in the radial direction and becomes less than the radial position PA wherein PA wherein a radial distance between PA