Cathode ray tube having triangular gun array and curvilinear spacing between the fourth and fifth grids

Claim 1

A cathode ray tube comprising an evacuated envelope, a plurality of electron guns within said envelope each gun of said plurality being at the vertex of a triangle for producing a plurality of electron beams having a triangular configuration, at least two cylindrical electrodes arranged in consecutive order and surrounding the path of said beams, the ends of said electrodes confronting each other and defining an effective boundary line providing an aberration reducing electrostatic field for said electron beams, said effective boundary line having a shape resulting from the combination of two sine curves, the period of one being twice the period of the other, a luminescent screen positioned within said envelope to intercept said electron beams, a shadow mask electrode within said envelope between said electron gun and said screen, said shadow mask electrode being proximately spaced from and parallel to said screen, said cylindrical electrodes substantially converging said beams in the plane of the shadow mask electrode, said screen comprising a plurality of different luminescing substances, said electron gun producing a plurality of beams corresponding to the number of different luminescing substances, the distance between said effective boundary line and said screen having maximum values at areas of points of intersections of the line which forms said effective boundary with the axes of said electron beams.