| 摘要 |
PURPOSE:To prevent the adjusting quantity of a contrast control resistor from giving influence on the value of a gain control resistor, by providing the gain control resistor on the base of a base-grounded amplifier. CONSTITUTION:The titled circuit is constituted of one emitter-follower circuit which inputs a contrast control voltage by the contrast control resistor VR1, that is, a transistor Tr1, the base-grounded amplifier driven by the transistor Tr1, that is a transistor Tr2, and the gain control resistor VR which adjusts a collector voltage by adjusting the base voltage of the transistor Tr2. A voltage Vo performs parallel displacement while keeping an inclination angle theta as it is in the case of varying the gain control resistor VR. Thereby, constant inclination can be obtained, and no gain ratio of every color is varied by adjusting contrast, and it is possible to keep stable color balance.
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