| 摘要 |
PURPOSE:To enable to obtain color picture even at a weak electric field, by changing the operating point of a color killer circuit of a color television receiver according to the variance of electric field strength. CONSTITUTION:The color killer adjusting circuit consisting of a burst gate circuit 2, burst amplifier circuit 3, transformer L2, resistors R4-R8, capacitors C4-C6, and diodes D1, D2, is connected to a detection circuit 5 detecting the variance of electric field strength. Further, when the strength of electric field is weak, the potential at point (A') is small, the transistor TR2 is not ON, and the color killer circuit is not operated even at a weak electric field. Accordingly, no color regardless of the presence of chrominance input signal, can be prevented. |
