Patent ID: 7957241
Filing Date: 2011-06-07
Classification: G11B

Abstract:
1. A method for detecting defect signals on an optical disc, which uses a finite state machine (FSM) to control a servo system of an optical disk drive, the method comprising the steps: (A) setting a detection counter to a first predetermined value and making the FSM enter an ARM state when the defect signals in a DETECT state are greater than corresponding thresholds; (B) making the FSM enter a KICK state when the detection counter in the ARM state has count-down from the first predetermined value to zero, and setting the detection counter to a second predetermined value; (C) asserting a XDFCT flag signal when the FSM is in the KICK state, and making the FSM enter a WAIT state when the detection counter in the KICK state has count-down from the second predetermined value to zero, then setting the detection counter to a third predetermined value; and (D) making the FSM enter the DETECT state when the detection counter in the WAIT state has count-down from the third predetermined value to zero; wherein when the XDFCT flag signal is asserted, corresponding servo control signals for the servo system is clamped to a programmable constant voltage to prevent a laser beam of the optical disk drive sliding from a original track to a neighboring track due to a false signal produced.