| 摘要 |
PURPOSE:To obtain a liquid crystal video display with correct stepped tone, high contrast and bright display, by erasing gamma compensation for cathode ray tube made for a video signal and making the gamma compensation again for the liquid crystal. CONSTITUTION:A characteristic diagram indicates an input and output voltage characteristic of a gamma compensation circuit of this invention, in which a curve corrected with the inverse characteristics of liquid crystal characteristics is shown after an input video signal is compensated with the gamma of a cathode ray tube. The input video signal is inputted to a TR1 after the reproduction of DC component with C1 and D1. When a black level signal smaller than E1 is applied, D1 and D2 are both turned off and the gain of this circuit is R1/R2. Next, when a signal of intermediate level which is greater than the E1 and smaller than the E1+E2 is applied, the gain is greater as R1/ R2X(R2+R4)/R4, and when a greater white level signal is applied, the gain is further increased and a characteristic required for the liquid crystal display can be obtained. Thus, the liquid crystal video display with the highest contrast, correct stepped tone and bright screen can be obtained by giving the gamma compensation characteristic matched to the liquid crystal. |
