| 摘要 |
PURPOSE:To attain high speed access by detecting the actual linear velocity of a disk, storing the speed and correcting and retrieving the track number read from an address table corresponding to the actual line velocity. CONSTITUTION:The actual line velocity of a disk 2 is detected by a linear velocity detection circuit 13 and the actual linear velocity of the disk to be detected is stored in the linear velocity memory 14. A track number from the start point of the disk inner circumference with respect to each address calculated by the designated linear velocity is stored in the address table 15. A CPU 7 corrects track numbers X1, X2 read from the disk 15 based on the ratio of the actual linear velocity and designation linear velocity, obtains the track number to be jumped from corrected track numbers X1', X2' to retrieve the object address. Thus, the jumping track number is always accurate independently of the difference of the linear velocity of each disk, which is used for the optical pickup feed control at random access to attain high speed random access.
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