Patent ID: 8085631
Filing Date: 2011-12-27
Classification: G11B

Abstract:
1. A tracking control device for converging a main beam and a sub beam on an information recording medium having plural information layers, and controlling a convergence point of the main beam to scan a track on the information layer, the tracking control device comprising: a tracking error signal detecting section which detects a tracking error signal depending on a positional displacement between the convergence point of the main beam, and the track on the information layer; and a tracking control section which controls the convergence point of the main beam to scan the track, based on the tracking error signal detected by the tracking error signal detecting section, wherein the tracking error signal detecting section includes: the tracking error signal detecting section includes a switch which switches between a first state where the sub push-pull signal passing the low pass filter is inputted to the tracking error signal generating section, and a second state where the sub push-pull signal before the input to the sub push-pull signal correcting section is inputted to the tracking error signal generating section; and the tracking control device further includes: an information layer number detecting section which detects the number of the information layers of the information recording medium, and a switching control section which controls the switch to the first state, if at least two information layers are detected by the information layer number detecting section, and controls the switch to the second state, if one information layer is detected by the information layer number detecting section.