| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical disk device which can stably perform focus control by adjusting balance of a focus error signal used for focus control. SOLUTION: A focus error signal which is a difference signal between the sum of amounts of reflective light detected by photo-detection elements A, C and the sum of amounts of reflective light detected by photo-detection elements B, D in a tetrameric photo-detector, is measured. With respect to the focus error signal, when the amount of reflective light from the optical disk detected by the tetrameric photo-detector is maximized, a level is set as a reference level, and gains of amplifiers 23, 24 are individually adjusted so as to make a maximum value and a minimum value of the focusing signal almost symmetric in sandwiching the reference level. Therefore, focus control can be performed stably by using the balance adjusted focus error signal. COPYRIGHT: (C)2003,JPO
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