| 摘要 |
PURPOSE:To prevent a blanking from being started or released on the way of screen by controlling the timing of the generation and stop of a blanking signal based on a vertical synchronizing signal. CONSTITUTION:A channel data SCH is applied from a channel selection section 22 to a CPU12, the channel selection is started and the data SCH is written in an RAM14. When a vertical synchronizing signal Vsync is applied to a terminal 25, interruption takes place, a set signal SSE is applied to an FF24 to set the FF24 and a blanking signal SQ is applied to a video amplifier 5 from the FF24 to apply blanking to a video signal. Then, a channel selection data SDATA based on the data SCH is read from an ROM13 and applied to a frequency divider 8 for attaining channel selection. When the channel selection is started, a station detecting signal Sd is applied to a CPU12 from a signal detecting circuit 23. When the channel selection is finished, the CPU12 discriminates the supply of the signal Vsync, applies a reset signal SRE to the FF24 to reset the FF24 to release the blanking. |
