| 摘要 |
PURPOSE:To eliminate the noise on a screen in a picture searching mode, by setting an auxiliary head to each rotary video head and using with automatic switching the output of an adjacent auxiliary head in case the output level of an auxiliary head drops. CONSTITUTION:The reproduced outputs of video heads A and B' are supplied to switches 14 and 17 via preamplifiers 12 and 13 respectively. The reproduced outputs of video heads B and A' are supplied to the switches 14 and 17 via preamplifiers 15 and 16 respectively. The switches 14 and 17 are controlled by the head switching pulse. The output of the switch 14 is fed to a luminance reproducing/processing circuit 18 and a chrominance reproducing/processing circuit 19 as well as to an envelope detector 22. The output of the switch 17 is fed to a luminance reproducing/processing circuit 20 and a chrominance reproducing/processing circuit 21 as well as to an envelope detector 23. The reproduced luminance signal of the circuit 18 and the reproduced chrominance signal of the circuit 19 are fed to a synthesizer 24, and the output of the synthesizer 24 is supplied to a switch 26. The circuits 20 and 21 have the same constitution. The outputs of the detectors 22 and 23 are fed to a comparator 28 to be compared for their levels with each other. |
