| 摘要 |
PURPOSE:To obtain a stable horizontal output by supplying the composite output consisting of the horizontal and vertical synchronizing signals of a personal computer to a video signal processing circuit through a resonance circuit which has a resonance frequency nearly equal to the color burst frequency of a television receiver. CONSTITUTION:A graphic and character information signal inputted from a personal computer 38 are inputted to R, G, and B input terminals 35, 36, and 37 and the horizontal and vertical synchronizing signals H and V are inputted from terminals 33 and 34 to obtain the composite synchronizing signal (a) of the horizontal and vertical synchronizing signals from an AND gate 23. The output signal (a) of the AND gate 23 is divided by resistances 24 and 25 and passed through the resonance circuit (resonance frequency: 3.58MHz) consisting of a capacitor 26 and a coil 27 to obtain a waveform (b). This is supplied to a video input changeover switch 5 through a transistor (TR) 32 and further inputted to the video signal processing circuit 11 through a TR6. Thus, the operation of the processing circuit 11 is locked with a ringing waveform of 3.58MHz superposed on the composite synchronizing signal to obtain the stable horizontal output.
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