PURPOSE: To ensure the automatic correction to the flickering on the screen caused by the output level difference by adding the comparison level information to the video signal through two units of memory circuit and then detecting the level difference of the comparison level information to give the control to the bias of the memory circuit.
CONSTITUTION: The input signal is applied to memory circuits 41 and 42 via the waveform shaping circuit block. In that case, the DC comparison level is written to the signal information through memory circuits 45 and 46, and then changed into different levels through circuits 41 and 42 to be then delivered. These output signals, after passing through LPF53 and 54, are sampled only for the comparison levels through analog switch circuits 55 and 56 to be turned to signals 57 and 58. These signals are turned to DC comparison levels 61 and 62 through holding circuits 59 and 60 to be then applied to differential amplifier 63. In case some difference exists among the comparison levels, voltage generation circuit 64 starts operation to generate DC bias voltage 65 and 66 which are set previously. Thus the DC level difference is corrected between circuits 41 and 42.
WASHIJIMA NORIYUKI
KITANI TERUO
SASAKI REIICHI
