| 摘要 |
To provide an interlayer movement apparatus of an optical disc apparatus which can perform the interlayer movement stably even when the interlayer distances of the multi-layer optical disc which are specified by the disc specification are different between the respective layers. In an interlayer movement apparatus for moving the focal point of the laser light to an arbitrary layer, there are provided an objective lens which collects the laser light from an optical source, a focus actuator which makes the objective lens move in its optical axis direction, a focus error detection means for detecting the convergent state of the laser light on the information layer of the optical disc, and an interlayer movement control system for making the focal point of the laser light move to an information layer two or more layers apart by controlling the focus actuator according to a relative speed between the information layer of the optical disc and the focal point which was calculated using the time required for the focal point of the laser light passing through the respective layers which was measured on the basis of the output signal of the focus error detection means and the respective interlayer distances which are specified by the optical disc specifications.
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