| 摘要 |
PURPOSE:To prevent always modulation turbulence by a stripe filter regardless of a change in illuminance by detecting the change in a luminance signal, making a correction signal and controlling gains of a modulation signal by this correction signal. CONSTITUTION:An output signal from an image pickup tube 1 is added to a LPF3 and a BPF4 through an amplifier 2, and a luminance signal from the LPF3 is taken out. The luminance signal is added to a difference detection circuit 6, and a pulse (difference pulse) of the difference of luminance is taken out. The pulse is added to a positive signal circuit 7. Said circuit 7 removes a pulse in the positive direction out of the difference pulse, and takes out a correction pulse only for a pulse in the negative direction. The correction pulse is added to an AGC circuit 8, and a modulation signal is corrected by controlling gains of the AGC circuit 8. As a result, turbulence of the modulation signal due to a change in illuminance can be corrected. |
