| 摘要 |
PURPOSE:To improve the precision of landing at a target place and to speed up access by detecting the number of eccentric tracks of disk half rotation, and finding the eccentricity correcting value until the time when a pickup lens reaches the target place and adding it to the counted value of the number of traverse tracks. CONSTITUTION:Traverse track waveform signals from sensors 15, 19, and 20 are converted into clock signals to actuate a FF18, whose Q output goes up to 'H' through a half disk rotation; and the quantity of eccentricity of the number of tracks that the sensors cross is held in a counter 6 at the end of one turn. A microcomputer 1 calculates an eccentricity correcting value up to the target place on the basis of an input eccentricity quantity according to a track access instruction and the track conversion value obtained by adding the calculated value to the number of traverse tracks up to the target value is preset in a counter 7. Then, the pickup lens moves radially on a disk in rotation with a pickup mechanism feed signal from the microcomputer 1, the counter 7 outputs a coincidence signal when a clock equal to a track converted value is inputted, and the microcomputer 1 stops the driving of a motor 14, thereby finishing the access.
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