| 摘要 |
PURPOSE:To negate a sub beam component mixed in a main beam, and to reduce a fault, such as a ghost, etc., by performing the interface addition of a part of an output signal from the sub beam on the output signal from the main beam. CONSTITUTION:Each of a main beam 10, and sub beams 12 and 14 from an optical pickup 1 is irradiated respectively from an objective lens 16 to a video disk 18, and reflected light beams are received as a six divided photodiode 22. A main reflected beams 10' of the beams 10 are received at a four divided photodiode 24 at a center in the diode 22, and reflected beams 12' and 14' of the sub beams 12 and 14 are received at tracking photodiodes 26 and 28. The output of each of the diodes 24, 26, and 28 is processed at a focus circuit 70 and a tracking servo circuit 80, then being added on the pickup. And a part of the outputs of the diodes 26 and 28 is antiphase-added on the output signal from the diode 24 at the adder 40, and the components of the beams 12 and 14 mixed in the beams 10' are negated, thereby facilitating a process at a signal processing circuit 67.
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