| 摘要 |
PURPOSE:To improve the receiving condition by blocking the operation of a color killer with a control voltage of an automatic gain control circuit at a weak electric field so as to guarantee the coloring of a picture even at a weak electric field to some degree. CONSTITUTION:Even if the color killer circuit 26b which does not stop the operation of red and blue color difference signal detecting circuits so far as a normal color broadcast signal is received at a strong electric field or a middle electric field, is going to stop the operation of the color difference signal detecting circuits in case of the receiving of black/white broadcast signal or the like because of the effect of external noise mixed in the color broadcast signal at a weak electric field, a coloring guarantee circuit 33 operated by the control voltage of an automatic gain control circuit 8 specific to the weak electric field receiving blocks the operation of the color killer circuit 26b so as to obtain a colored picture to some degree even at a weak electric field. |
