| 摘要 |
PURPOSE:To improve the stability of the black level, by fixing the level of the flyback period in a video signal at an optional level and the compensating the DC level of the video signal in accordance with the level of the peak voltage at the black side. CONSTITUTION:The output of a pedestal clamping circuir 5 is supplied to the base of a transistor TR16 via a diode 14. At the same time, the blanking signal given from the output point B of a buffer inverting circuit 6 is superposed on the base of the TR16 after uniforming the peak level. As a result, video signal received a waveform process is obtained at the point C. Accordingly the voltage corresponding to the negative side peak of the base input waveform of the TR16 is obtained at the output point D of a rectifying circuit formed with a diode 18, etc. The voltage at the point D is superposed on the voltage having positive polarity which emerges at the output point E of the circuit 6, then the variation of the black level can be correctly compensated. |
