Color television display apparatus having improved convergence of electron beams

Claim 1

In a color television display apparatus comprising: a color cathode ray tube integrally structured by a neck region at the back, a display screen at the top and an intermediate funnel region connecting said neck region and said display screen; an electron gun apparatus disposed within said neck region of said cathode ray tube, having means for producing three horizontal in-line electron beams and a magnetically-permeable focusing electrode for focusing the beams; a deflection yoke disposed about said neck region and said funnel region of said cathode ray tube, including a core and vertical deflection coils toroidally-wound about said core, said coils producing a deflection magnetic field having deflection magnetic flux located within the interior of said yoke for effecting deflection of said beams in a vertical direction and leakage flux located external to said yoke; and magnetically-permeable means disposed adjacent to said yoke, for channeling a portion of said leakage flux beyond the rear of said yoke to the vicinity of the beam exit end of said electron gun apparatus for forming a barrel-shaped magnetic field at said exit end for interaction with said electron beams; the improvement wherein said magnetically-permeable means comprises first, second and third portions, said first portion being positioned adjacent to the rear end surface of said core, extending toward the center axis of said neck region in a direction perpendicular to said center axis, for receiving leakage flux produced mainly in said rear end surface of said core, said second portion extending backward from the outer end of said first portion, for transmitting backward the flux received by said first portion, and said third portion being connected to the rear end of said second portion, extending toward the center axis of said neck region in a direction perpendicular to said center axis, and being positioned corresponding to the beam exit end of said electron gun apparatus, said third portion functioning to emit said flux transmitted through said second portion to said beam exit end.