| 摘要 |
PURPOSE:To raise the correction of a track jump error by controlling a moving speed so that the frequency detector of a ripple portion in a pickup output becomes equal to a track jump number per unit time from its output signal. CONSTITUTION:As for the operation of the time of a jump control, a pickup 13 moves toward an object track by a jump command. A spot S moves in the direction as indicated with an arrow by a focus servo, cross the track, and photodetecting quantity of a photodetecting part 17 is varied. Frequency generated in its output signal corresponds to the moving speed of the pickup, detected by a detector 29, and the output of an FV transducer 30 is varied in accordance with the frequency, the moving speed of the pickup 13 is controlled variably so that the number of tracks crossing per unit time of an optical beam becomes constant. The number of tracks crossed by the spot per unit time becomes constant, therefore, a substantially exact search operation is executed. Therefore, the error of a track jump in a speed varying period is corrected sufficiently. |
