| 摘要 |
PROBLEM TO BE SOLVED: To obtain a stable focus servo pull-in operation even in the case in which the recording density and also the thickness of disk are different, by starting the operation of a focus servo means in accordance with the focus error signal. SOLUTION: A focus means 7 is moved so that the focus of a beam corresponding to plural information recording media 8 is positioned extremely near the recording surface of the information recording medium 8, and the focus pull-in means 43, 23, 21, 22, 26 are operated by the obtained focus error signal 19, then the operation of the focus servo means 29, 30 are started. After the irradiated position of beam on the information recording surface of the information recording medium 8 is moved, the operation of the focus servo means is started by operating the focus pull-in means. |
