Color picture tube apparatus

Abstract

A color picture tube apparatus comprises auxiliary electrodes provided between first and second focusing electrodes, a nonaxisymmetric electrostatic lens is generated between the auxiliary electrodes and a focusing lens is generated between the first focusing electrode and the auxiliary electrode. A dynamic voltage V.sub.d is applied to the first and second focusing electrodes. Consequently, the effect of compensating the astigmatism of the electron beam caused by the deflection magnetic field and the defocus of the electron beam can be increased, the dynamic voltage can be decreased, and as a result, the cost of the circuit can be reduced. As the focusing function of the additional focusing lens is weakened and the electron beam trajectory is expanded, the magnification of the lens both at the center and the periphery of the screen can be equalized substantially and the uniformity of the focus of the electron beam between that at the center of the screen and that at the periphery of the screen becomes high.

Dependencies are inferred from the claim text.