| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical disk device where an optimal position of an objective lens for using the optical disk can be determined considering the displacement and the curvature of the recording layer of the optical disk, even when using optical disks with large displacement and curvature of recording layer, and to provide its focus control method. SOLUTION: The optical disk device includes a memory 13 storing a reference focus value, and a CPU 14 which generates a first modified focus value by adding a predetermined value to the reference focus value and a second modified focus value by subtracting a predetermined value from the reference focus value. The CPU 14 records a test data based on the reference focus value, and determines which of the reference focus value and the first and second modified focus values should be used for recording the test data, based on the ratios of the positive-side amplitude amount and the negative-side amplitude amount of the focus error-signal generated when the test data is reproduced, to the reference voltage. COPYRIGHT: (C)2009,JPO&INPIT
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