| 摘要 |
PURPOSE: A method of performing a focus jump of a multilayer disk is provided to control the size of a drive force for the focus jump between recording layers of a laser beam in consideration to disturbance caused by the focus jump and DC sensitivity deviation every actuator, thereby exactly carrying out a jumping operation between the recording layers. CONSTITUTION: When a disk jumps to the second recording layer from the first recording layer, a detected focus error signal is presented as the first S curve(S1) and the second S curve(S2). A signal(115) generated by a laser beam reflected from a disk surface is detected prior to the first and the second curves. A focus error signal is sampled to detect a time(t1) when the signal is detected from the disk surface, and detects a time(t2) when the first curve starts to be detected. A reference time interval(tk0) consuming between the times(t1, t2) and an optimum reference kick force(fk0) are decided. A time interval(tk) between the times(t1, t2) is measured after applying the reference kick force. The measured time interval is compared with the reference time interval. If the measured time interval is bigger, the kick force is set to a bigger state than the reference kick force. If the measured time interval is smaller, the kick force is set to a small state.
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