| 摘要 |
PURPOSE:To obtain an optical pickup device incorporating in advance a photodetector and a reproducing preamplifier by disconnecting electrically the preamplifier from the photodetector at the position adjustment of the photodetector. CONSTITUTION:In opening switch contacts 16a-16d by operating externally a circuit switch at the assembling of the photodetector 10, an electric signal from the photodetector 10 is sent to an external output terminal 15, a position adjusting preamplifier 14 connected to the output terminal in advance is driven, the photodetector 10 is moved in X, Y axes by the change in the output to adjust the mounting position. In this case, since the gain of the preamplifier 14 is fixed and the gain of the current/voltage conversion circuit is decided by components with high accuracy, an electrical signal from the photodetector 10 is converted to voltage without variance, then an electric signal from the photodetector 10, not only the relative value but also the absolute value of I-I is measurable. When the adjustment of the position of the photodetector 10 is finished, the position adjustment preamplifier 14 is removed from the output terminal 15, switching contacts 16a-16d of the circuit switch 16 are closed and the circuit is combined with a CD player.
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