| 摘要 |
PROBLEM TO BE SOLVED: To prevent collision of an objective lens with an optical disk. SOLUTION: The optical disk device includes a focus error signal generating unit that generates a focus error signal based on reflected light from an optical disk, and a focus control unit that generates, from the focus error signal, a driving signal to control the focus of an optical pickup to output it. The focus control unit includes a first filter adjusting unit that turns ON a first filter adjusting signal when the absolute value of the focus error signal is equal to or more than a first error threshold, a proportional term computing unit that multiplies the focus error signal by a predetermined value, an integral term computing unit that multiplies the focus error signal by an integral term gain to integrate the product, a differential term computing unit that differentiates the focus error signal, and an adder that adds up the computing results of these computing units to output the addition result as the driving signal. The integral term computing unit reduces the integral term gain when the first filter adjusting signal is ON. COPYRIGHT: (C)2011,JPO&INPIT
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