| 摘要 |
PURPOSE:To eliminate the fluctuation of a video signal in a video signal processing means in response to an adjustment signal by applying the adjustment signal from a generating means to a video signal processing means in place of the video signal nearly in a vertical blanking period. CONSTITUTION:A pulse generating circuit 30 outputs a clock to a test signal generator 41 by an input of a vertical synchronizing signal from a synchronizing separator circuit 21. A test signal outputted from the circuit 41 by the signal is subjected to noise rejection by a LPF 42 and a switch 43 is connected to the position of test signal. The test signal biased to a prescribed voltage by clamp lines 13, 14 is fed to switches 31, 32, charged in sampling capacitors 52, 54, only a difference voltage is amplified by a 2nd differential amplifier 34 and inputted to a LPF 36. The LPF 36 eliminates high-frequency components from the signal and sends the result to a bias circuit 37 to change the bias voltage of the 1/2H delay line 11 by the fluctuation only. Thus, each charge voltage of the capacitors 52, 54 is controlled to be equipotential, the output level of the circuits 13, 14 is made coincident to eliminate the fluctuation of the video signal of the video signal processing means.
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