Patent ID: 9064506
Filing Date: 2015-06-23
Classification: G11B

Abstract:
1. An information recording and reproducing apparatus configured to record and reproduce information in and from an optical disc comprising a guide layer with address information along a track groove and a recording layer with a sequence of recording marks in recording completed areas, the information recording and reproducing apparatus comprising: a guide layer focus control module configured to concentrate laser light with a first wavelength on the track groove through an objective lens and perform guide layer focus control using a focus error signal obtained from first reflected light from the track groove; an objective lens control module configured to perform guide layer tracking control by controlling the objective lens in accordance with a tracking error signal obtained from the first reflected light, and perform recording layer focus control by concentrating laser light with a second wavelength on the recording layer through the objective lens and control the objective lens using a focus error signal obtained from the second reflected light; a correction tracking control module configured to perform recording layer tracking control of the laser light with the second wavelength over the recording layer, using a tracking error signal obtained from the laser light with the second wavelength; and a calculation module configured to control, if the sequence of recording marks is detected, the correction tracking control module to cause the laser light with the second wavelength to be scanned over a sequence of recording marks which has the same address as that of a track groove over which the laser light with the first wavelength is scanned, and calculate an amount of relative misalignment between a track of the guide layer and a track of the recording layer, which have the same address, using a control signal which is supplied to the correction tracking control module at time of controlling the correction tracking control module, the control signal being defined based on correction values for guide layer tracking, the correction values being acquired all along one track at appropriate angular intervals, wherein in a case where additional recording is performed, the recording layer tracking control is performed while making correction based on the amount of the relative misalignment calculated by the calculation module, and the guide layer tracking control is performed under open loop control using the acquired correction values.