Cathode-ray tube with deflection amplification and post-deflection acceleration

Claim 1

In a cathode-ray tube of the known type that includes (a) an evacuated envelope, (b) an electron gun at one end of the envelope for emitting an electron beam, (c) a fluorescent screen at the other end of the envelope to be excited by the electrons of said beam, (d) a horizontal deflection system in the path of said electron beam, (e) a quadrupolar lens disposed in said path after said horizontal deflection system for amplifying the horizontal deflection of said electron beam, (f) a vertical deflection system in said path, (g) a quadrupolar lens disposed in said path after said vertical deflection system for amplifying the vertical deflection of said electron beam, one of said quadrupolar lenses being closer to said screen than the other, (h) a conductive coating forming part of a post-deflection acceleration system and lining the internal wall of said envelope from said screen to the quadrupolar lens closer to said screen and (i) a spherical cup-shaped post-deflection acceleration electrode forming part of said post-deflection acceleration system and at least partially surrounding the quadrupolar lens closer to said screen, said spherical cup-shaped electrode being provided with a slot, the configuration of which has an elongated outline formed of two opposite, arcuate, inwardly concave short sides and two opposite arcuate, inwardly convex long sides, and through which said electron beam passes subsequent to passing through the last-named quadrupolar lens, the improvement comprising A. a first planar disc-shaped electrode disposed in said path immediately before the quadrupolar lens closer to said screen and being provided with a slot having substantially the same configuration as that of the slot provided in said postdeflection acceleration electrode, the median plane of said slot in said post-deflection acceleration electrode and the median plane of said slot in said first planar disc-shaped electrode being at right angles with respect to one another and B. a second planar disc-shaped electrode disposed in said path between the last-named quadrupolar lens and the slot of said post-deflection acceleration electrode, said second planar disc-shaped electrode having an opening for the passage of said electron beam, said opening being symmetrical with respect to the directions of the vertical and horizontal scanning.