(19)
(11) EP 0 275 191 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
07.06.1989 Bulletin 1989/23

(43) Date of publication A2:
20.07.1988 Bulletin 1988/29

(21) Application number: 88300247.9

(22) Date of filing: 13.01.1988
(51) International Patent Classification (IPC)4: H01J 29/50
(84) Designated Contracting States:
DE FR GB IT

(30) Priority: 14.01.1987 GB 8700792
14.01.1987 GB 8700793
04.12.1987 US 128951

(71) Applicant: RCA Thomson Licensing Corporation
Princeton New Jersey 08540 (US)

(72) Inventors:
  • New, David Arthur
    Lancaster Pennsylvania (US)
  • Maninger, Loren Lee
    Lancaster Pennsylvania (US)

(74) Representative: Szary, Anne Catherine et al
London Patent Operation, GE Technical Services Co. Inc., Essex House, 12-13 Essex Street
London WC2R 3AA
London WC2R 3AA (GB)


(56) References cited: : 
   
       


    (54) Color cathode-ray tube having a three-lens electron gun


    (57) An improved color cathode-ray tube includes an electron gun for generating and directing three inline beams, a center beam and two side beams, along initially coplanar paths toward a screen of the tube. The gun includes, in order from its cathode end (K), a plurality of spaced electrodes (G1-G6) which provide a first (L1), a second (L2) and a third (L3) lens for focusing the electron beams. The first lens has a beam forming region for providing substantially symmetrical beams to the second lens. The improvement is in the combination of the second and third lens. The second lens includes at least one electrode (G4) to provide asymmetrically-shaped beams. The potentials applied to the second lens refract electron beams emerging off-axes from the first lens toward the axes. The third lens is a low aberration main focusing lens which provides asymmetrically-shaped beams of substantially constant current density to the screen.







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