| 摘要 |
PURPOSE:To reduce the access time of an optical beam to a track, by using a relative speed and a position mismatch signal after the completion of a coarse access. CONSTITUTION:An aberration signal 11 is a signal which represents a relative displacement between a beam, and the track, and the signal obtained by the differentiation of the signal, that is the relative speed is sent out to an output 17. The aberration signal 11 is inputted to a track passing pulse generation circuit 14, and a reference speed generation circuit 18, and the reference speed generation circuit 18 continues to count a track passing pulse 15, and sends out reference speed to an output 19. The relative speed 17, and the reference speed 19 are inputted to a speed error detection circuit 20, an a speed error is sent out to an output 21, and is inputted to a power amplifier 22, and is voltage-current converted, then it is supplied to an actuator 5. In this way, the access can be completed by one time accessing operation without receiving the influence of decentering at a moving time to plural tracks.
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