| 摘要 |
PURPOSE:To increase the quality of reproduced picture at the recorder by FM signal, by the control so that the operating point of optical modulator can be kept at a given position. CONSTITUTION:The output of the optical modulator 14 is branched into the information recording light flux and the drift monitor light flux 14c at the half mirror 15. This light flux 14c is converted into electric signal and fed to the specified narrow band filters 17, 18. Next, the outputs of the both filters are input to the differential amplifier 19 via the amplifiers 20, 21, and the difference signal is detected. Further, servo is operated so that this difference signal is zeroed to control the operating point of the optical modulator 14 and the information signal of the information signal source 24 is input to this operating point. Thus, the cross modulation component between the audio signal carrier and the video signal carrier can stationarily be suppressed, allowing remarkably to increase the quality of reproduced picture. |
