Patent ID: 7768880
Filing Date: 2010-08-03
Classification: G11B

Abstract:
1. A reproducing apparatus for reproducing data from a recording medium, comprising: head means for directing a laser light beam onto the recording medium and detecting laser light reflected from the recording medium to read the data, the head means having a focus servo mechanism and a spherical aberration correction mechanism for laser light; evaluation signal generating means for generating an evaluation signal serving as an index of quality of a reproduced signal based on the reflected light detected by the head means; focus servo means for performing a focus servo operation by driving the focus servo mechanism in response to a focus error signal generated as a signal responsive to the reflected light detected by the head means; spherical aberration correction means for performing spherical aberration correction by driving the spherical aberration correction mechanism in response to a spherical aberration correction value; focus bias means for adding a focus bias to a focus loop containing the focus servo means; and control means for controlling adjustment of a spherical aberration correction value to be set in the spherical aberration correction means and a focus bias value to be set in the focus bias means, wherein when a center point of an assumed margin predetermined for each of the spherical aberration correction value and the focus bias value is shifted to a shift point within a first predetermined search range in a first tilt direction, the value of the evaluation signal is obtained at each of a plurality of predetermined points within the assumed margin with respect to each shift point, the evaluation signal having the worst value from among the plurality of predetermined points is set to have a representative value of each shift point, and the spherical aberration correction value to be set in the spherical aberration correction means and the focus bias value to be set in the focus bias means are adjusted based on the spherical aberration correction value and the focus bias value at the center point when any of the representative values of the shift points having a value of the evaluation signal that is better by a predetermined amount is obtained; where the control means sets a second predetermined search range in a second tilt direction, the second tilt direction is different from the first tilt direction.