| 摘要 |
PURPOSE:To improve remarkably the deterioration of characteristic of an AGC circuit, by decreasing the waveform distortion including the deterioration in the synchronizing section amplitude of a recording luminance signal. CONSTITUTION:A video signal 1 is inputted to an AGC amplifier 2, transmitted to an LPF 6 via an LPF3 and a buffer amplifier 4 and its output is given to a synchronizing signal separating circuit 9. This signal is given to comparison amplifiers 29, 30 via a feedback type clamp circuit 41 in the circuit 9. The amplifiers 29, 30 have threshold values 35, 36 from reference power supplies 31, 32 respectively and output signals c, d corresponding to the values are generated. The signal (d) is applied to a clamp circuit 21 and the signal (c) is given to an AGC detecting circuit 24. Further, the threshold value 36 is set closer to the synchronizing tip of the output signal of the LPF6 more than the threshold value 35. Thus, the waveform distortion of a recording luminance signal outputted from the circuit 21 is reduced. |
