Patent ID: 7505386
Filing Date: 2009-03-17
Classification: G11B

Abstract:
1. A radial runout detection method for an optical disk drive, the optical disk drive using an optical pickup unit to generate a beam spot, the beam spot shaping a beam locus on an optical disk, thereby reading stored information of multiple data tracks on the optical disk, the method comprising the steps of: (A) setting a reference locus, which is a virtual locus at a predetermined location distant from a current beam locus by M (M is a positive integer) tracks; (B) setting a minimum track number M_MIN, a maximum track number M_MAX, and a detection time to execute steps (C) to (E) during the detection time; (C) increasing the track number M when a data track crossing the current beam locus on the optical disk moves toward a direction of the reference locus with respect to the current beam locus, and otherwise decreasing M; (D) setting the minimum track number M_MIN as the track number M when the track number M decreased is smaller than the minimum track number M_MIN; (E) setting the maximum track number M_MAX as the track number M when the track number M increased is greater than the maximum track number M_MAX; and (F) computing a runout track number by subtracting the minimum track number M_MIN from the maximum track number M_MAX.