Device for adjusting electron beams in a cathode-ray tube

摘要

A magnetic ring for adjusting color purity and convergence is secured to the electron gun of a color-picture tube. It encloses an oblong area which is perpendicular to the plane defined by the three electron beams produced by the electron gun. The shape of the magnetic ring is chosen so that the y-distance of the ring from the central axis of the central electron beam is greater than the distance of the ring from the respective central axis of an outer electron beam. This selection of distances influences the focus of the beams.