Convergence means for a plural beam color picture tube

Claim 2

In a color cathode-ray tube having means generating plural beams which are directed, at predetermined incident angles to each other for convergence on a screen, through horizontal and vertical deflection fields produced by electromagnetic deflection means and by which said beams are made to scan said screen, the improvement comprising magnetic shielding means disposed adjacent the paths of said beams through said deflection fields and being operative to selectively shield at least one of said beams from leakage flux from said horizontal deflection field while permitting said leakage flux to act on another of said beams for correcting deviations between the rasters of said plural beams on said screen.

Claim 3

A color cathode-ray tube according to claim 1, in which said plural beams originate in a common planE and include a central beam and opposite side beams, and in which said magnetic shielding means are positioned to permit only said central beam to be acted upon by said leakage flux while shielding said side beams therefrom.

Claim 4

A color cathode-ray tube according to claim 2, in which said magnetic shielding means includes two spaced-apart shielding members disposed at outer sides of the paths of said side beams and being shaped to collect and to direct around said side beams the leakage flux that would otherwise act on said side beams.

Claim 5

A color cathode-ray tube according to claim 3, in which each of said shielding members includes a substantially straight portion extending substantially parallel to and in spaced relation to the straight portion of the other shielding member, and end portions at the ends of said straight portion and being directed at substantial angles to the latter in the direction toward the corresponding end portions of the other of said shielding members.

Claim 6

A color cathode-ray tube according to claim 4, in which said common plane is horizontal and said straight portions of the yoke members extend substantially vertically so that said shielding members collect and direct around said side beams the leakage flux from the horizontal deflection field in the lateral regions through which said side beams pass.

Claim 7

In a single-gun, plural-beam color picture tube which includes a color screen having arrays of color phosphors and beam-selecting means provided with apertures corresponding to said arrays, beam-generating means for directing a central electron beam and two side electron beams in a common plane toward said screen for impingement on respective phosphors of each array through the corresponding aperture, lens means for focusing said electron beams on said screen and having an optical center at which said beams are made to cross each other with said side beams emerging from said lens means along paths lying in said plane and which are divergent with respect to the central beam, electron beam convergence deflecting means operative, upon the application of a convergence deflecting voltage thereto, to deflect said side beams emerging along said divergent paths for convergence of all of said beams at an aperture of said beam-selecting means, and deflection yoke means having sweep signals applied thereto to provide fields which deflect said beams in directions respectively parallel and at right t angles to said plane for causing said beams to scan said screen; the improvement comprising magnetic shielding means disposed adjacent the exit from said convergence deflecting means and shielding only said side beams from leakage flux from said field which deflects said beams in said direction parallel to said plane while permitting said leakage flux to pass unimpeded in a zone through which said central beam passes for correcting deviations in the direction of said plane between the positions of the rasters on the color screen produced by said beams in scanning said screen.

Claim 8

In a single-gun, plural-beam color picture tube which includes a color screen having arrays of color phosphors and beam-selecting means provided with apertures corresponding to said arrays, beam-generating means for directing a central electron beam and two side electron beams in a common plane toward said screen for impingement on respective phosphors of each array through the corresponding aperture, lens means for focusing said electron beams on said screen and having an optical center at which said beams are made to cross each other with said side beams emerging from said lens means along paths lying in said plane and which are divergent with respect to the central beam, electron beam convergence deflecting means operative, upon the application of a convergence deflecting voltage thereto, to deflect said side beams emerging along said divergent paths for convergence of all of said beams at an aperture of said beam-selecting means, and deflection yoke means having sweep signals applied thereto to provide fields which deflect said beams in directions respectively parallel and at right t angles to said plane for causing said beams to scan said screen; the improvement comprising magnetic shielding means disposed adjacent the exit from said convergence deflecting means and shielding only said side beams from leakage flux from said field which deflects said beams in said direction parallel to said plane while permitting said leakage flux to pass unimpeded in a zone through which said central beam passes for correcting deviations in the direction of said plane between the positions of the rasters on the color screen produced by said beams in scanning said screen.

Claim 9

A single-gun, plural-beam color picture tube according to claim 6, in which said magnetic shielding means includes spaced-apart shielding members arranged at the outer sides of said side beams and each having a substantially straight portion at right angles to said plane and end portions at the ends of said straight portion and being directed inwardly at substantial angles to the latter.