Color cathode ray tube having a low dynamic focus

摘要

An electron gun of a color cathode ra tube includes (1) a beam forming region having cathodes, a G1 electrode and a G2 electrode and (2) a main lens formed of plural electrodes including a G3 electrode supplied with a fixed focus voltage and an accelerating electrode. The main lens includes a final lens formed between the accelerating electrode and an electrode opposing the accelerating electrode and configured so that outer electron beats are deflected toward a trajectory of a center electron beam and a lens strength of the final lens weakens with beam deflection The electron gun also has at least one multipole lens located between the final lens and the beam forming region and configured so as to change a cross sectional shape of the electron beams with beam deflection, and a lens formed between a pair of electrodes located between the final lens and the beam forming region and having axially spaced opposing surfaces each having opposing center beam apertures and opposing outer beam apertures. The centers of the opposing outer beam apertures in the opposing surfaces are displaced from each other in a direction perpendicular to the electron gun axis. The lens formed between the pair of electrodes focuses the electron beams in both horizontal and vertical directions and changes a focusing strength thereof with beam deflection and deflects the outer electron beams toward or away from the center electron beam with beam deflection.