DE2265368

A color television display system is described which requires no dynamic convergence apparatus for small and medium size screen color picture tubes and which requires relatively simple dynamic convergence apparatus for large screen color picture tubes. The color picture tube includes an electron gun assembly for producing three adjacent horizontal in-line coplanar beams. The electron gun assembly includes a common three-aperture beam forming electrode for establishing precise alignment of the beams. The beams are substantially converged at all points in the scanned raster as they are deflected by a deflection yoke providing negative horizontal isotropic astigmatism and positive vertical isotropic astigmatism. The gun assembly includes magnetic shield members disposed around the two outside beam paths to shield those beams from a portion of the deflection field so that the rasters scanned by the three beams are of the same size. In addition, the color picture tube includes a faceplate having repeating groups of three different color phosphor strips and an aperture mask including a plurality of elongated slit apertures disposed adjacent the phosphor strips to enhance the light output from the picture tube.