| 摘要 |
PROBLEM TO BE SOLVED: To solve such problems that it is required to add an exclusive sensor for detecting displacement from an optical axis center of a direction crossing a track of a tracking actuator, thereby increasing a product cost, also deviation from the optical axis center caused by a DC offset component included in an output signal of the sensor causes occurrence of new vibration. SOLUTION: In this apparatus, displacement quantity from the optical axis center of an objective lens can be detected by only adding a signal processing circuit consisting of a differential amplifier or the like by diverting a part of a signal outputted from a photodetecting means provided originally for detecting a focus error by an astigmatism method. A filter means for reducing or eliminating the DC offset component is provided so that deviation is not caused when feedback control is performed even when the DV offset component is included in a displacement quantity signal. COPYRIGHT: (C)2007,JPO&INPIT
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