| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a technique for quickly and stably moving a focus from one layer to another in order to perform focus control with respect to each recording layer of a disk having a plurality of recording layers, while no influence is absorbed by disturbance or a change in the movement speed of an objective lens. <P>SOLUTION: A means for monitoring a signal level of a focus error signal, a means for removing noise from the focus error signal, a means for detecting the movement speed of the objective lens, and a speed control voltage-generating means for generating a voltage for controlling the objective lens based on the movement speed obtained from the speed detecting means, are used to detect the movement speed of a lens and apply a drive signal for the objective lens corresponding to the movement speed when the focus is moved from one layer to another, and decide a location where the focus finally moves, based on the behavior of the focus error signal which is obtained just before the focus movement is ended. As a result, the focus is forcibly moved from a focus point on a recording surface of one recording layer to a focus point on a recording surface of another recording layer, i.e., focus control is stably achieved. <P>COPYRIGHT: (C)2011,JPO&INPIT |
