Picture display tube and display device provided with such a tube.

摘要

By causing in a device for displaying pictures with a display tube and a self-converging system of deflection coils (24) the focusing in the direction in which the focusing is substantially independent of the deflection by the system of the deflection coils (24) to take place by means of two quadrupole lenses (22, 23) and by the focusing lens (13, 14, 15) in the direction at right angles thereto, it becomes possible to use dynamic focusing in said latter direction without defocusing in another direction. In this manner it becomes possible to obtain a sharp spot all over the screen.
<??>By providing an octupole lens coaxially around the electron beam and the centre of the focusing lens it also becomes possible to reduce the spherical aberration.