| 摘要 |
PURPOSE:To make an action stable and highly speedy and to execute the track access up to a goal track in a short time by shifting in the initiative manner the converging lens while the number of shifting tracks are directly counted, when shifting is executed from the present track to the goal track. CONSTITUTION:When the track access device of the optical disk shifts an optical spot 9 from the present position track to the goal track, a stroke signal from the external control circuit to the goal track is inputted through a counter 7 to a reference speed generating circuit 16 and a control circuit 17. At the circuit 17, the front part of the goal track is detected, a switch 19 is changed over to an A side and the reference speed from the circuit 16 is inputted into a speed detecting circuit 12. At the circuit 12, the difference with the speed signal of a converging lens 8 is calculated, a speed error signal is applied through the switch 19 and a driving circuit 20 to a lens actuator 7, the speed of the optical spot 9 is controlled to the value corresponding to the reference signal and the track access time up to a goal track is shortened.
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