| 摘要 |
PURPOSE:To prevent the generation of sag, stabilize synchronization, and to prevent luminance tilting and to maintain stability and quality of a picture, by grasping the state of disturbance by a frequency discriminating function, and setting automatically on optimum corresponding AGC time constant CONSTITUTION:An input signal Vi is amplified by an amplifier circuit 11, and an amplified signal is detected by a detector circuit. The detected output Vo is applied to the first and second comparator detector circuits 13-1, 13-2. At the same time, a reference voltage Vr corresponding to synchronizing signal level from a reference bias circuit 14 for controlling is applied to circuits 13-1, 13-2. Time constant circuits 16, 17 are attached to circuits 13-1, 13-2 and the outputs of circuits 13-1, 13-2 are inputted to an AGC switching circuit 15. A detected output Vo is applied to a frequency discriminator 26 through level detector circuits 24, 25 to grasp the state of disturbance. The circuit 15 is controlled by a discrimination output Vc of the discriminator 26, the outputs of circuits 13-1, 13-2 are selected and the time constant is set automatically. |
