| 摘要 |
PURPOSE:To prevent distortion of a character and a graph to be displayed by forming a current fed to a vertical deflection coil of the video display device using a cathode ray tube to be a stepwise wave so as to form a horizontal scanning line without setting down right while eliminating a change in the vertical deflection current for the horizontal scanning period. CONSTITUTION:The circuit is provided with a counter counting an inputted horizontal synchronizing signal 10 and reset by an input vertical synchronizing signal 11, a D/A converter 13 converts the count output of the counter into a step wave, the step wave is amplified and fed to a vertical deflection coil 15 mounted to a cathode ray tube. Moreover, An output of the counter 12 is branched and fed to a decoder 17 detecting a value in excess of a maximum horizontal scanning line number within one vertical scanning period and a detection output 18 of the decoder 17 and the inputted vertical synchronizing signal are ORed and the output is fed to a reset input of the counter 12. |
