DEVICE AND METHOD FOR JUDGING ADVANCING DIRECTION OF LIGHT SPOT, DEVICE AND METHOD FOR CONTROLLING OPTICAL HEAD, AND OPTICAL DISK RECORDING AND REPRODUCING DEVICE

摘要

PROBLEM TO BE SOLVED: To judge an advancing direction of a laser spot to the radial direction of a disk only by a difference signal without using a summing signal. SOLUTION: A differential amplifier circuit 34 calculates a difference signal Ma-Mb between a detection signal Ma and a detection signal Mb obtained from a 1st photo-detector 30. A differential amplifier circuit 35 calculates a difference signal S1a-S1b between a detection signal S1a and a detection signal S1b obtained from a 2nd photo-detector 31. A comparator 36 binarizes the difference signal Ma-Mb of a main spot M. A comparator 37 binarizes the difference signal S1a-S1b of a side spot S1. A judging part 38 judges the advancing direction of the main spot based on the binarized data obtained from the comparator 36 and 37.