| 摘要 |
PROBLEM TO BE SOLVED: To perform accurate focus control. SOLUTION: The device is provided with an irradiation means for irradiating an optical disk with a light beam, an actuator for adjusting focus of the light beam for the optical disk, an RF signal generating means for generating an RF signal being a data reproduced signal based on reflected light from an optical disk medium, a focus error signal generating means for generating a focus error signal based on reflected light from the optical disk medium, a region discriminating means for discriminating a region by corresponding values of the RF signal generated by the RF signal generating means and values of focus error signals generated by the focus error signal generating means in the two dimensional coordinate, and a control means controlling the focus actuator based on the discriminated result of the region discriminating means, then, such control of the focus actuator can be performed that influence by variation of reflectance of the optical disk medium, eccentricity components of the optical disk medium, or the like are suppressed to the minimum. COPYRIGHT: (C)2008,JPO&INPIT
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