| 摘要 |
An optical disc drive (1), capable of handling optical discs (2) with at least two storage layers (61, 62), comprises an axially displaceable objective lens (34) and a focus actuator (52) for controlling the axial position of the objective lens; a control circuit (90) for generating actuator control signals (SQF) for the focus actuator; and a threshold source (98) for providing a threshold level (VT) lower than a supply voltage (Vs) for the focus actuator. The control circuit (90) monitors a focus disturbance signal and delays a layer jump if the absolute value of the focus disturbance signal is too high. Particularly, the control circuit compares the absolute value of the disturbance signals with said threshold level and, if this absolute value is higher than said threshold level, inhibits (83) the layer jump until the absolute value of the disturbance signals becomes lower than said threshold level.
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