SMEAR SIGNAL ELIMINATING CIRCUIT IN TELEVISION CAMERA

PURPOSE:To eliminate effectively a smear signal by extracting the smear signal in a vertical blanking period of a video signal, storing cyclially it and adding the stored smear signal in opposite phase to the original video signal. CONSTITUTION:A reset pulse is applied to an input terminal 10 in the period of verical scanning, a reset FET 5 is turned on during the pulse period, a sampling pulse of the same period is applied to an input terminal 9, and a sampling gate FET 4 is turned on uring the pulse period. As a result, a signal in the vertical blanking period applied to the input terminal 8 is extracted during this period and the smear signal is stored sequentially onto a 1H delay line 3. The smear signal is stored cyclically in the delay line 3 and transistors (TRs) 6, 7 until the signal is cleared at the next vertical blanking period. This signal is led out in opposite phase from the emitter of the TR 7 and applied to an adder 2. The smear signal is cancelled in the adder 2 and only the video signal eliminated the smear signal is introduced onto the output terminal 12.