| 摘要 |
PURPOSE:To make possible to resolve indistinctness due to hue abnormality by performing the achromatism of a video signal with operating an achromatism circuit when the presence of an additional vertical synchronizing signal is detected by an additional vertical synchronizing signal detecting circuit and performing the achromatism in a special reproducing with a simple circuit constitution. CONSTITUTION:When the video signal is inputted from a terminal A, the synchronizing signal of it is separated by a synchronizing separation circuit 4. The separated synchronizing signal is supplied to a deflection circuit 5 and also, it is impressed on an additional vertical synchronizing signal detecting circuit 6. So that the additional vertical synchronizing signal is added on in the special reproducing mode of a VTR, it is detected by the additional vertical synchronizing signal detecting circuit 6. And a color video signal from a signal circuit 1 is achromatized by the detected signal at a circuit 2 and is impressed on a beam index tube 3. Thus, a picture on the scope of the beam index tube is monitored as a black-and-white picture.
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