| 摘要 |
PURPOSE:To perform change-over and channel selection for two channels automatically, by performing the channel change-over with the output pulse having desired time width frequency dividing the vertical synchronizing pulse. CONSTITUTION:The saw tooth wave picked up from the vertical deflection circuit 2 is fed to the vertical deflection coil 3 and also fed to the wave shape circuit 4 into the synchronizing pulse wave-shaped and fed to the frequency divider 5. This synchronizing pulse is the frequency divided output waveform the period of which is extended according to the number of stages of the frequency divider 5. The frequency dividing output selected at the switching period selection switch S1 to pick up the frequency dividing output having desired period and time is fed to the differentiation circuit 6, the differentiation output drives the timer circuit 7 to obtain the output pulse of a given time width, and this output pulse is fed to the switching circuit 8 to select the main channel and the sub-channel via the sub and main channel selection switch S2, allowing the automatic change-over to the subchannel only for a given time width. |
