Patent ID: 7719931
Filing Date: 2010-05-18
Classification: G11B

Abstract:
1. An optical disk device for recording information in a first region and a second region of an information carrier having two or more regions of different track pitch, or for reproducing information that has been recorded, the first region being formed with a track pitch different from a track pitch of the second region, said optical disk device comprising: a focusing unit operable to focus an optical beam and direct the optical beam at the information carrier; a movement unit operable to move the focal point of the optical beam focused by the focusing unit in a radial direction of the information carrier; a light receiving unit operable to receive the optical beam reflected by an information side of the information carrier; a track offset detection unit operable to detect offset between the track and the focal point of the optical beam on the basis of a signal from the light receiving unit; a tracking control unit operable to drive the movement unit on the basis of a signal from the track offset detection unit, and to control the focal point of the optical beam so as to scan the track; a loop gain adjustment unit operable to adjust a first loop gain used in tracking control of the first region, which is the loop gain of the tracking control unit; and a loop gain estimation unit operable to estimate a second loop gain used in tracking control of the second region, wherein the loop gain estimation unit