Farbanzeigesystem und Röhre, versehen mit einer an zwei Elektroden modulierten Elektronenkanone

An improved color display system includes a cathode-ray tube (10) and a magnetic deflection yoke (30) positioned on the tube. The tube includes an envelope (11) having an inline electron gun (40) for generating and directing three inline beams (28) along initially coplanar paths toward a screen (22) on an interior surface portion of the envelope. The gun includes a plurality of spaced electrodes which comprise three lenses. The first lens (L1) includes a beam-forming region for providing substantially symmetrical beams to a second lens (L2). The second lens includes a first modulation electrode (50) for providing asymmetrically-shaped beams to a third, or main, lens (L3) At least one, but preferably two, dynamic voltage signals (126,130) are applied to the modulation electrode of the second lens. Another dynamic voltage signal (128) is applied to a second modulation electrode portion (54) of the third lens. The voltage signals are related to the deflection of the beams and improve the electron beam spot size at the periphery of the tube screen.