Color crt drive apparatus having automatic white balance adjusting

Abstract

A picture tube drive apparatus for driving a color picture tube. The picture tube drive apparatus comprises a video output circuit which receives video signals, amplifies them and outputs the amplified video signals, a picture tube drive circuit which receives the video signals amplified by the video output circuit for driving said color picture tube based on video signals, the picture tube drive circuit having a detector for detecting a beam current corresponding to the brightness of each color flowing through the picture tube, a picture tube connected with the picture tube drive circuit for displaying the video signals, a white balance control circuit into which a detection value of a beam current detected by the picture tube drive circuit is inputted and for outputting video signal level compensation signals for adjusting the white balance of the video image displayed on the picture tube to the picture tube drive circuit. A color picture tube in which an electron shield frame having at most a width which will not prevent electron beam from flying onto said shadow mask from an electron gun and having a function to suppress the reflection of the electron beam on a fluorescent screen is disposed on the inner peripheral surface of said electron on the side of the electron gun with respect to a shadow mask mounting position in the color tube.