| 摘要 |
In order to reproduce signals from a double-layer optical disc having two signal recording surfaces, a focus jump that the focusing of an objective lens from the one signal recording surface to the other signal recording surface is quickly achieved, is necessary. When a focus error signal (FE) from a pickup (60, 70) reaches a predetermined threshold value (Vcomp), a deceleration signal for decelerating the objective lens (42) is supplied to an actuator (47). Preferably, a deceleration pulse voltage is lowered step by step. The deceleration pulse voltage is determined in accordance with the maximum value (DFEmax) of a differential focus error signal (DFE) generated by differentiating the focus error signal (FE). Preferably, the address seeking is done simultaneously with the focus jump. The focus jump is performed in accordance with the layer-to-layer distance which is measured beforehand. The focus jump is performed by using a lens (143) having a controllable focal distance. Preferably, whether the layer is the first layer or the second layer is judged based on the reflected luminous power. If the focus error signal (FE) from the other layer is not obtained even when a certain time passages after the focus jump is started, the objective lens (42) is moved in the reverse direction.
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