Abstract: A color display tube having an electron gun system for producing three in-line electron beams. The system includes, in the direction of travel of the beams, a first electrode, a second electrode and a plurality of focusing electrodes, each having apertures for passing the beams. The second electrode includes two spaced-apart plate-shaped members, each having a central and two outer apertures for passing the beams. The apertures in the members for each outer beam are laterally shifted with respect to each other and with respect to a corresponding aperture in the first electrode to direct the outer beams toward convergence with the inner beam.

Abstract: The spot quality of an electron beam produced by an electron gun in a cathode ray tube is improved by optimizing the dimensions of a beam-forming, apertured electrode arrangement in the gun. This arrangement includes electrodes for forming a cross-over followed by, in the direction of propagation of the electron beam, first and second lens electrodes centered around an axis, for defining an accelerating and prefocusing lens and at least two lens electrodes for defining a main focusing lens. The diameter of the aperture in the second lens electrode is smaller than twice the diameter of the aperture in the first lens electrode, and the effective spacing S-eff between the first and the second lens electrodes is smaller than 1 mm. S-eff is defined as the minimum of the function ##EQU1## where .DELTA.