Circuit for displaying screen control states of a monitor

A circuit for displaying mode frequencies and screen control states of a monitor using OSD (on-screen-display) letters, comprising:

• means for generating a blanking signal having a voltage at either a first logic level or a second logic level;
• pre-amplifying means having a blanking gate terminal for receiving said blanking signal and for amplifying a signal output from a video card when said blanking signal received at said blanking gate terminal is at said first logic level, or blanking the signal output from the video card when said blanking signal received at said blanking gate terminal is at said second logic level;
• OSD means for displaying on a screen the mode frequencies and the screen control states using the OSD letters in accordance with R (red), G (green), B (blue) signals, while the output of said pre-amplifying means is blanked in response to said blanking signal at said second logic level;
• buffer means coupled to said OSD means for delaying the R, G, B signals form said OSD means for predetermined time;
• mixer means for mixing the output of said pre-amplifying means and the output of said buffer means to generate a mixer output signal;
• amplifying means for inversely amplifying said mixer output signal to a voltage signal suitable for driving a CRT (cathode ray tube);
• and
• bias means for DC-coupling the output of said amplifying means and biasing a CRT voltage to a predetermined voltage to provide the biased CRT voltage to cathode electrodes of the CRT.