Color convergence system having elongated magnets perpendicular to plane of plural beams

Claim 1

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 first and second side electron beams in a common plane toward said color screen for impingement on respective phosphors of each array through the corresponding aperture, lens means for focusing said electron beams on said color screen and having an optical center through which said beams are all passed with said central beam being coincident with the optical axis of said lens means and said side beams being oppositely angled with respect to said optical axis to enter said lens means along paths that are convergent to said optical axis from opposite sides of the latter and to emerge from said lens means along paths divergent to said axis at opposite sides of the latter, electron-beam-convergencedeflecting means interposed between said lens means and said beam selecting means and being operative to deflect said side beams emerging along said divergent paths for convergence of said side beams with said central beam at said beam selecting means, and deflection yoke means located between said convergence deflecting means and said beams selecting means and receiving horizontal and vertical sweep signals to cause said beams to scan said screen; the improvement comprising first and second elongated permanent magnets each having ends of opposite polarities, said first and second magnets extending generally perpendicular to said common plane at the outer sides of said first and second side beams, respectively, at a location therealong between said lens means and said beam selecting means and being disposed with said polarities of said first magnet reversed with respect to said polarities of said second magnet to produce respective magnetic fields having lines of magnetic flux extending generally perpendicular to said common plane and in opposed directions, and mounting means for said first and second magnets permitting the individual displacement of each magnet in directions toward and away from the adjacent one of said side beams, whereby to vary the effect, in the direction of said common plane, of each of said magnetic fields on the adjacent side beam and on said central beam for correcting any misconvergence of said beams.