Patent ID: 8018807

Claim:
A method of compensating for misalignment in an optical disk device, the method comprising: detecting focus error signals at a plurality of locations including a first location which corresponds to an initial location of an objective lens and second locations of the objective lens which correspond to predetermined displacements from the first location in radially inward and outward directions, wherein at least one of the second locations arranged at the radially outward direction relative to the first location include a series of locations or the second locations arranged at the radially inward direction relative to the first location include a series of locations; detecting magnitudes of the focus error signals; and shifting radially the objective lens according to the detected magnitudes of the focus error signals to reduce misalignment in the optical disk device, wherein each focus error signal is generated independently of information corresponding to a drive signal for moving a position of the objective lens to a corresponding one of the first and second locations.