| 摘要 |
a preposition amplifier for amplifying the output signal of a video card to a predetermined level when a high signal is applied to a blanking gate(BLK GATE), and blanking the output of the video card when a low signal is applied to the blanking gate(BLK GATE); an OSD means for displaying a mode frequency and a screen control state with OSD characters on the screen by R, G and B signals while a blanking signal is applied to the blanking gate(BLK GATE) to blank the output of the amplifier; a buffer means for delaying the R, G and B signals of the OSD means for a predetermined period; a mixing menas for mixing the output of the preposition amplifier and the buffer means; an amplifying means for invert-amplifying the output of the mixing means to a appropriate voltage level to drive a CRT; and a bias means for performing a bias for the CRT voltage to a predetermined voltage level after DC-coupling the output of the amplifying means, and applying the bias voltage to the cathode of the CRT.
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