| 摘要 |
PURPOSE:To insure a picture against disturbance even if a horizontal frequency fluctuates by fixing the output voltage of a frequency/voltage converter circuit 31 of a horizontal deflection system to the voltage in accordance with the horizontal frequency of the prescribed composite video signal. CONSTITUTION:A switch circuit 101 outputs a control signal for switching the circuit 101 to the side of a fixed voltage source 102 under such condition that the signal supplied to an input terminal 3 selects a video, the signal supplied to the terminal 3 selects an RGB and the signal supplied to an input terminal 24, and the signal supplied to an input terminal 106 is at zero level (superimpose). Thus the prescribed conditions are discriminated at the time of arbitrary R, G and B signals such as superimpose, and the output voltage of a frequency/ voltage converter circuit 13 of a horizontal deflection system is fixed to the voltage in accordance with the horizontal frequency of the prescribed composite video signal. Thus a picture will not be disturbed even if the horizontal frequency fluctuates. |
