| 摘要 |
PURPOSE:To always obtain a correct index singal, by subtracting a video signal component to be applied to the cathode of an index tube or a modified component of the video signal component from the signal that is detected by an index signal detector. CONSTITUTION:The output of the index signal detector 16 is put into the substractor 203 after passing through the band pass filter 17. On the other hand, a part of the video signal to be applied to the cathode 5 of the optical index tube 1 is also supplied to the filter 23 through the band pass filter 22 and after having a gamma-exponent given by the power multiplier 21 and substrated from the signal supplied from the detector 16. Then an index signal of a correct phase in delivered from the subtractor 23. This index signal is shaped through the amplitude limiter/amplifier 18 to process the carrier chrominance signal by a color signal process circuit, then the resultant is added with the monochrome signal through the adder 20 to apply to the cathode 5 of the index tube 1. |
