Patent ID: 8149671
Filing Date: 2012-04-03
Classification: G11B

Abstract:
1. An optical disc drive with the ability to read and/or write data from/on an optical disc with multiple information layers including a first information layer and a second information layer, the drive comprising: an objective lens for converging a light beam; a lens actuator for driving the objective lens; a photodetector section, which receives the light beam that has been reflected from the optical disc and converts the received light beam into an electrical signal; and a control section for determining values of a first group of parameters, which are set to read data from the first information layer, and values of a second group of parameters, which are set to read data from the second information layer, during a disc loading process, wherein the first group of parameters includes first spherical aberration information that defines the magnitude of spherical aberration correction to be made on the light beam at the first information layer, and the second group of parameters includes second spherical aberration information that defines the magnitude of spherical aberration correction to be made on the light beam at the second information layer, wherein in performing the disc loading process, the control section determines values of the first group of parameters first, and then determines values of the second group of parameters based on the values of the first group of parameters that have just been determined during a current disc loading process and on correlation information, which represents a correlation between a first distance calculated based on the first spherical aberration information that was set during a previous disc loading process and a second distance calculated based on the second spherical aberration information that was set during the previous disc loading process, the first distance representing a distance from the surface of the light incoming side of the optical disc to the first information layer, and the second distance representing a distance from the surface of the light incoming side of the optical disc to the second information layer, and wherein the correlation information has been stored on the optical disc when the current disc loading process is started.