Color CRT system and process with dynamic quadrupole lens structure

• US 5,036,258 A
• Filed: 08/11/1989
• Issued: 07/30/1991
• Est. Priority Date: 08/11/1989
• Status: Expired due to Fees

• Current Assignee: Zenith Electronics Corporation (LG Corporation)
• Original Assignee: Zenith Electronics Corporation (LG Corporation)
• Inventors: Gorski, Richard M., Chen, Hsing-Yao
• Primary Examiner(s): Blum, Theodore M.
• Application Number:
  US07/392,630
• Time in Patent Office: 718 Days
• Field of Search: 315/14, 315/15, 315/382, 315/382.1, 313/414, 313/449
• US Class Current: 315/382
• CPC Class Codes: H01J 2229/4841 Dynamic potentials
• CPC Class Codes: H01J 2229/4865 rectangle
• CPC Class Codes: H01J 2229/4872 circular
• CPC Class Codes: H01J 2229/4879 non-symmetric about field scanning axis
• CPC Class Codes: H01J 2229/4893 Interconnected apertures
• CPC Class Codes: H01J 29/503 Three or more guns, the axes of which lay in a common plane
• CPC Class Codes: H01J 29/51 Arrangements for controlling convergence of a plurality of beams by means of electric field only
• CPC Class Codes: H01J 29/628 co-operating with or closely associated to an electron gun

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.

Claims

1. For use in focusing a plurality of electron beams on a screen of a color cathode ray tube, wherein said electron beams are aligned in an in-line array and are deflected across said screen by an asymmetric magnetic field which causes astigmatism of said electron beams, an electron gun comprising:

first and third electrodes each adapted to receive a common dynamic voltage and each having for each beam a keyhole-shaped, horizontally oriented opening through which the electron beam passes;

a second electrode between said first and third electrodes adapted to receive a fixed voltage and having for each beam a vertically oriented, keyhole-shaped aperture,

said first, second and third electrodes, when excited, establishing dynamic quadrupole fields effective to compensate the electron beams for said beam astigmatism.

2. For use in focusing a plurality of electron beams on a screen of a color cathode ray tube, wherein said electron beams are aligned in an in-line array and are deflected across said screen by an asymmetric magnetic field which causes astigmatism of said electron beams, an electron gun comprising:

first and third electrodes each adapted to receive a common dynamic voltage and each having for each beam a keyhole-shaped, horizontally oriented opening through which the electron beam passes;

a second electrode between said first and third electrodes adapted to receive a fixed voltage and having for each beam a circular aperture,

said first, second and third electrodes, when excited, establishing dynamic quadrupole fields effective to compensate the electron beams for said beam astigmatism.

3. For use in focusing a plurality of electron beams on a screen of a color cathode ray tube, wherein said electron beams are aligned in an in-line array and are deflected across said screen by an asymmetric magnetic field which causes astigmatism of said electron beams, an electron gun comprising:

first and third electrodes each adapted to receive a common dynamic voltage and having a horizontally elongated slot through which the electron beams pass;

a second electrode between said first and third electrodes adapted to receive a fixed voltage and having for each beam a circular aperture,

said first, second and third electrodes, when excited, establishing dynamic quadrupole fields to the electron beams effective to compensate for said beam astigmatism.