(19)
(11) EP 0 244 826 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
12.04.1989 Bulletin 1989/15

(43) Date of publication A2:
11.11.1987 Bulletin 1987/46

(21) Application number: 87106502.5

(22) Date of filing: 05.05.1987
(51) International Patent Classification (IPC)4: H01J 29/46
(84) Designated Contracting States:
DE FR NL

(30) Priority: 05.05.1986 US 859572

(71) Applicant: TEKTRONIX, INC.
Beaverton Oregon 97077 (US)

(72) Inventor:
  • Odenthal, Conrad J.
    Portland Oregon 97215 (US)

(74) Representative: Liska, Horst, Dr.-Ing. et al
Patentanwälte H. Weickmann,K. Fincke,F.A. Weickmann, B. Huber,H. Liska,J. Prechtel,B. Böhm Postfach 86 08 20
81635 München
81635 München (DE)


(56) References cited: : 
   
       


    (54) Multiple beam electron discharge tube having beam convergence and beam-to-beam compression compensation


    (57) The invention concerns a multiple beam electron discharge tube (16) comprising beam-producing means (24) for producing plural beams of electrons directed along a beam axis (26) in the tube (16) toward a display screen (28,30) positioned at one end of the tube (16); deflection means (32) for deflecting the electron beams relative to the beam axis (26) to produce an image on the display screen; convergence means positioned between the beam-producing means (24) and the deflection means (32) for converging the electron beams, the convergence means including a first electrode structure (10) that is electrically isolated from and positioned upstream of a second electrode structure (36) that has a limiting aperture through which the electron beams propagate; and first biasing means for providing between the first and second electrode structures a first potential difference of an amount that directs through the limiting aperture a substantial number of the electrons in each one of the beams.






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