Display device

Abstract

A display device capable of removing a defocused beam spot on the focusing screen by obtaining the fluctuation of a focusing voltage following the fluctuation of a high-tension voltage. There is applied a DC voltage of a predetermined high-tension voltage. Also, there is supplied a dynamic focus (DF) correction waveform such as a parabolic waveform voltage or the like matched with horizontal and vertical deflections or the like, for dynamically controlling the focusing in accordance with the shape of the tubular surface of a cathode-ray tube or the like. Further, there is supplied a peak focus (PF) correction waveform voltage corresponding to the fluctuation of the high-tension voltage. The DF correction waveform and the PF correction waveform are added by an adder. An added signal from the adder is amplified by an amplifier to 600 to 800 Vp-p, for example. Further, the correction waveform thus added and amplified and the above-mentioned DC voltage are added by an adder, and this added voltage is applied to a focusing grid, e.g. fourth grid (G4) of the cathode-ray tube.

Dependencies are inferred from the claim text.