| 摘要 |
PURPOSE:To accurately detect the movement amount of a pickup by counting the number of times of the pickup traverses a track when the pickup is moved at a fast speed radially of a disk, by counting the number of revolutions of the disk, and adding or subtracting the count values depending on the moving direction of the pickup. CONSTITUTION:The signals of a prescribed period synchronized with the rotation of the disk 11 is supplied to a pulse generating circuit 31, turned into signal (c), the signals (d) at a rate of one pulse per disk rotation is produced and supplied together with the output of the counter 18 to an adder/subtractor 33. The switching between the addition and subtraction is by the signals indicating the feed direction of the pickup 13 supplied from a feed motor control circuit 15. By such construction, the number of rotation of the disk 11 and the number of times the pickup 13 traverses the track are counted and the movement amount of the pickup 13 can be correctly detected by a simple construction.
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