| 摘要 |
PURPOSE:To attain highly accurate and fast access by setting a servo gain different from the locking of automatic tracking AT and/or at automatic focusing AF and after locking. CONSTITUTION:The position B side of a switch 203 is opened and the position C side is closed by using a control signal 5 and a switch 3 is closed to short- circuit a capacitor C1. In moving an optical point in a direction (u) on a card, a voltage at a point B whose sign only is reversed with respect to a voltage VA0 of a point A appears. The position C side of the switch 203 is opened and the position B side is closed by using the control signal 5 at times ts1, ts2 when a voltage at a point A is zero to close the track servo system. No coil 111 is driven with a driver 204 at 0 level, a lens is not driven at the AT locking and excellent access to a desired track is attained. The switch 3 is opened by using the control signal 5 at the AT stabilization and a pint C1 is opened and the gain frequency characteristic (a) between the points A and B is obtained and the rack servo is applied at a conventional gain characteristic increased at a low frequency region.
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