LENS SHIFT DETECTION METHOD, TRACKING CONTROLLER AND OPTICAL DISK DEVICE

摘要

PROBLEM TO BE SOLVED: To provide an optical disk device stable in terms of a system without the need of gate signals at all by holding the maximum value and minimum value of the low band components of the difference signals of divided and arranged photodetectors and correcting a tracking offset by using lens shift detection signals generated from the average value. SOLUTION: A band-pass filter 5 eliminates the DC components and high band components of the difference signals HFDIF and supplies obtained low band passing signals LFDIF to a maximum value holding means 6 and a minimum value holding means 7 and the maximum value and minimum value of low band difference signals LFDIF are respectively held. An adder 8 obtains the average value of the maximum and minimum values and turns it to lens shift detection signals LSDET. After subtraction is performed to tracking error signals TE by a subtractor 10 and the tracking offset is eliminated, the lens shift detection signals LSDET are fed back to a tracking actuator 2d by a tracking control means 3.