| 摘要 |
PROBLEM TO BE SOLVED: To prevent the generation of such a problem that the excessive time is required for erasing all data recorded on a disk due to the necessity to trace tracks by laser beams emitted from an optical head for erasing real data recorded on the disk. SOLUTION: When all of the data recorded on the disk are erased, the balance adjustment of the tracking servo in the optical disk is controlled so as to be shifted from the proper track position, or the balance adjustment of the focus servo is controlled so as to be shifted from the proper focussing position, then the laser beams from the optical head is allowed to emit so as to spread over the adjacent two tracks or three tracks, and also the output level of the laser beams of the optical head is set so that the recorded data on the two tracks or three tracks are erased. Thus, the recorded data on the two tracks or three tracks are simultaneously erased, and the reduction of the time required for erasing all of the real data recorded on the disk is attained.
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