| 摘要 |
PURPOSE:To speedily jump tracks without any influence due to eccentricity of tracks by accessing a track in a mode of following up a virtual track position obtained by adding the extent of track eccentricity of time series stored in a memory and the extent of movement to a target position. CONSTITUTION:A track eccentricity signal (h) of time series outputted by a position detector 2 is stored in a storage circuit 3, and this output and the output of a computing element 6 are added by an adder 8 to generate a virtual track position signal (p). The virtual track position signal (p) is converted back to an analog signal by a D/A converter 9, and the difference from the track eccentricity signal (h) is operated by a subtractor 5 to obtain a following-up control signal C. Since intersections on an optical disk are converged on the virtual track position signal (p) if a tracking actuator 1 is so driven that the following-up control signal C is zero, a changeover switch 4 is switched to servo control at the time when the following-up control signal C is zero. Thus, the track jump is smoothly and quickly completed.
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