Magnetic focusing type cathode ray tube

Claim 1

A magnetic focusing type cathode ray tube comprising: a glass envelope including a faceplate on which a screen is formed, a funnel portion integral with said faceplate, and a neck portion integral with said funnel portion; electron gun means positioned in said neck portion to project a plurality of electron beams toward said screen along beam paths substantially parallel to said neck portion, said plurality of electron beams being positioned in line; and magnetic focusing means positioned in front of said electron gun means along the beam paths within the neck portion, and including permanent magnet means for generating a focusing magnetic field and a magnetic yoke assembly having at least first and second magnetic yoke members, each of said first and second magnetic yoke members having a plurality of cylindrical magnetic yoke portions through which said electron beams can pass respectively and a common magnetic yoke portion which surrounds all said beam paths, said magnetic yoke members being positioned in such a manner that said plurality of cylindrical magnetic yoke portions of the first magnetic yoke member are spaced from that of the second magnetic yoke member at a given distance along the beam paths, and each of the common magnetic yoke portions of said first and second magnetic yoke members reducing the strength of a radial magnetic field component of said focusing magnetic field.