| 摘要 |
<p>The whole reflection signal and a tracking error signal are detected (S320) while an objective lens (17) is being moved in the radial direction of an optical disk (91), and the temporal difference between a time (t 1 ) at which the value of the whole reflection signal becomes a maximum and a time (t 2 ) at which the value of the tracking error signal becomes zero is detected in a predetermined time period (S340,S350). In addition, a value which is obtained by dividing the temporal difference by the time period of one cycle of the tracking error signal (CYCLE T) is acquired as a tilt appearance magnitude (S360). Relational information in which a tilt appearance magnitude and a tilt correction magnitude corresponding to the tilt appearance magnitude are associated is read out (S380), and the relational information read out and the current tilt appearance magnitude detected by a tilt-appearance-magnitude detection circuit are compared, thereby to determine the tilt correction magnitude necessary for a tilt correction (S390). The tilt correction magnitude is notified to a tilt correction circuit, and is used in making the tilt correction (S400).</p> |
