Color crt system and process with dynamic quadrupole lens structure

Abstract

For use in a color cathode ray tube (CRT) having a self-converging yoke for applying an asymmetric magnetic field in a synchronous manner to a plurality of inline electron beams for deflecting the electron beams across a phosphorescing screen in the CRT, wherein the magnetic field causes defocusing of and an astigmatism of the electron beams where incident upon the CRT screen in off-center regions of the screen, an electron gun comprising: a cathode for generating electrons; a beam crossover arrangement for receiving electrons from the cathode and for forming a beam crossover; a first electrostatic quadrupole field aligned in a spaced manner along the electron beams and having a first asymmetric aperture through which the inline electron beams pass for applying a first electrostatic quadrupole field to the electron beams in compensating for the defocusing and astigmatism of the electron beams; and a second electrostatic quadrupole field aligned in a spaced manner along the electron beams with the first electrostatic quadrupole field and having a second asymmetric aperture through which the inline electron beams pass for applying a second electrostatic quandrupole field to the electron beams for further compensating for the defocusing and astigmatism of the electron beams.