| 摘要 |
PURPOSE:To obtain an acceptable white balance ranging from low brightness to high brightness by providing at every primary color with resistance dividing circuits consisting of a resistance to which video signals are inputted in an end and other end is connected with FET's drain and a variable resistor connecting with a space across FET's sources and earths. CONSTITUTION:In case of the low brightness, as a resistance value between the drain and source of FET 7 is sufficiently lower, the variable resistor connecting with the space across the source and earth of FET 7 contributes to the dividing ratio of resistance dividing circuits comprising a resistance 6, FET 7 as well as the variable resistor 8. Therefore, the amplitude value of video signal in such a case of low brightness can be so optionally controlled at every primary color that a desired drive voltage ratio is obtained. This procedure not only can cope with the variance of both brightness of a cathode ray tube and drive voltage characteristics but also compensate the variance of FET's saturated resistances and obtain the acceptable white balance ranging from low brightness to high brightness.
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