LASER NOISE ELIMINATING CIRCUIT AND OPTICAL DISK DEVICE

摘要

PROBLEM TO BE SOLVED: To always efficiently eliminate only laser noise from an RF signal and to prevent a circuit from being saturated in writing.

SOLUTION: In a laser noise eliminating circuit and in an optical disk device, it is possible to always eliminate only laser noise efficiently from the RF signal and also it is possible to prevent the circuit from being saturated in writing by making the gain of a TIA 8 high during reproduction and also by cutting the DC component of an FPD signal which is obtained by subjecting a part of the laser beam to the photoelectric conversion with a photodetector 6 and the TIA 8 by a high-path filter 105 from the RF signal which is obtained by subjecting a reflected light from an optical disk (not shown) of a laser beam to a photoelectric conversion with a photodetector 2 and a TIA 4 and subtracting it with a subtractor 102 and also by making the gain of the TIA 8 high in reading data from the optical disk and moreover by making the gain of the TIA 8 low in writing data to the optical disk.

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