Patent ID: 8208354
Filing Date: 2012-06-26
Classification: G11B

Abstract:
1. An optical disc apparatus, for executing recording or reproducing on an optical disc having at least two (2) recording/reproducing layers, comprising: an optical pickup, having: a sphere aberration compensating portion, which is configured to set up a compensation volume of the sphere aberration; an objective lens; a driver portion, which is configured to drive said objective lens; and an obtaining portion, which is configured to obtain a gain for a reproduction signal; wherein said sphere aberration compensating portion sets up said compensation volume to a compensation volume corresponding to an intermediate position laying between a deepest layer and a most front layer from said optical pickup; said driver portion drives said objective lens in a direction of approaching to said optical disc, when said compensation volume is set at a compensation volume corresponding to said intermediate position; said sphere aberration compensating portion sets up said compensation volume at a compensation volume corresponding to said deepest layer, when said objective lens is driven in a direction of approaching to said optical disc; said driver portion drives said objective lens in a direction of separating from said optical disc, when said compensation volume is set to the compensation volume corresponding to said deepest laver; and said obtaining portion obtains a gain for said reproduction signal on each layer of said optical disc, upon basis of amplitude of said reproduction signal, which is obtained when approaching said optical pickup to said optical disc, and amplitude of said reproduction signal, which is obtained when separating said optical pickup from said optical disc.