| 摘要 |
PURPOSE:To prevent a misconvergence by projecting a convergence drift detecting signal in the neighborhood of the center positions of an upper, a lower, a right, and a left side of a screen in a short time, detecting the signal by a beam detector, and correcting a convergence waveform based on a detected output. CONSTITUTION:As for AND gates 18R, 18G, and 18B, when the R output, that is the output of an RGB switching circuit 24, is at a high level, only and AND gate 18R is conducted, and signals phi101-phi101 and phi10 are supplied to the CRT20R of an R, and the deviation of a beam of the CRT20R of the R in a horizontal and a vertical directions are detected. The same operations are performed for a G, and B. Meanwhile, the currents are conducted to convergence coils 22R, 22G, and 22B, by static convergence circuits 21R, 21G, and 21B and the beams of the R, the G, and the B are moved in the vertical and the horizon tal directions. In this way, since the drift of a CRT beam can be detected and corrected without affecting a display screen, no deviation of the convergence is generated even when an enlarged projection is performed on a large screen.
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