Patent ID: 7440377

Claim:
A method for adjusting a focus bias in an optical disc drive, comprising the steps of: rotationally driving an optical disc in a state that only a focus servo is engaged without engaging a tracking servo; driving an actuator of an optical pick-up so that a laser beam projected from the optical pick-up is moved oscillatingly in a tracking direction, thereby intentionally creating a pseudo state resembling a state in which the tracking servo seems to be actually engaged so as to obtain a first HF signal in such a state from data on-track positions of the optical disc in the tracking direction; passing the thus obtained first HF signal into a peak/bottom holding circuit to obtain a second HF signal which apparently looks like a signal obtained only from data of all the on-track positions of the optical disc; adding a focus bias to the thus obtained second HF signal so that the amplitude of the second HF signal is increased or decreased; and determining an optimum focus bias at which the largest amplitude of the second HF signal is obtained.