| 摘要 |
PURPOSE:To oscillate a vertical synchronizing signal with a fixed frequency without following up the vertical synchronizing signal by selectively switching and outputting the voltage signal from a frequency/voltage converting means and the prescribed constant voltage signal by a switching means and controlling the freqnency of a vertical oscillation means. CONSTITUTION:The voltage signal corresponding to the frequency of the vertical synchronizing signal from, for example, a personal computer is applied via the switching means 7 to a vertical oscillation control means 9 when the above-mentioned synchronizing signal is applied to a frequency/voltage converting means 3. The saw tooth signal which follows up the vertical synchronizing frequency of the vertical oscillation means 5 and synchronizes therewith is oscillated and outputted from the vertical oscillation means 5. On the other hand, The switching means 7 outputs the constant voltage signal from a voltage constant voltage source means E to the vertical oscillation control means 9 when a CRT display device is switched and operated to the reception of, for example, television broadcasting and an indication signal is outputted to the switching means 7. The vertical oscillation control means 9, therefore, fixes the oscillation frequency of the vertical oscillation means 5 in accordance with the constant voltage signal thereof. The exact vertical deflection signal corresponding to the vertical synchronizing signal of the video signal of a prescribed mode is oscillated and outputted in this way with respect to the above-mentioned video signal. |
