US 6,194,824 B1Granted

Color cathode ray tube with astigmatism correction system

AssigneeMatsushita Electronics Corporation

InventorYasuyuki Ueda

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Abstract

Four magnetic pieces are provided inside the cup-shaped portion of a shield cup. Correction magnetic field generating faces at the tips of the magnetic pieces are opposed to each other and sandwich an electron beam. Correction can be conducted according to the astigmatism amount of three electron beams because a correction magnetic field corresponding to the strength of a deflection magnetic field can be generated easily by leading the deflection magnetic field absorbed by the principal face portion of each magnetic piece to the correction magnetic field generating face. Thus, the difference in astigmatism amount among the electron beams caused by the deflection magnetic field can be corrected. Therefore, a color cathode ray tube apparatus that can display images with a high resolution over the whole screen surface can be provided.

Claims4

Dependent claims

A color cathode ray tube apparatus comprising:

a color cathode ray tube comprising an in-line type electron gun for emitting three electron beams;
a self-convergence type deflection yoke, wherein the electron gun comprises a correction system for correcting a difference in astigmatism amount among the three electron beams emitted from the electron gun;
wherein the color cathode ray tube allows horizontal and vertical forces to act on the electron beams on both sides among the three electron beams arranged in line, and the horizontal force acting on the electron beam on one side is prescribed to be opposite in direction to the horizontal force acting on the electron beam on the other side, and the vertical force acting on the electron beam on one side is prescribed to be opposite in direction to the vertical force acting on the electron beam on the other side, whereby the difference in astigmatism amount caused between the electron beams on both sides is corrected.

Dependencies are inferred from the claim text.