| 摘要 |
PURPOSE:To color a subordinate screen without using an A/D converter and D/A converter by writing direct in a memory a color subsignal that has the subcarrier component of a B-channel broadcast of a two-screen receiver. CONSTITUTION:A signal received by antenna 3 is supplied to main-creen tuner 4 and sub-screen tuner 11. This signal showing that the A-channel broadcast has been selected by tuner 4 is applied to intermediate frequency amplifying and video detecting circuit 5, which outputs main signal SA as its detection output to mixer circuit 6. On the other hand, the signal of the B-channel broadcast is channel-selected by tuner 11 and applied to intermediate frequency amplifying and video detecting circuit 12 and as its detection output, sub signal SB is obtained and written in memories 14 and 15 via switch 13. Sub signal SB is extracted via switch 18 and, after having a clock component removed by LPF19, is applied to mixer circuit 6, where it is mixed with main signal SA. The composite signal has three primary signals R, G and B modulated and is applied to CRT9. |
