In-line type electron gun for a color picture tube

Abstract

In a conventional construction of an electron gun with quadrupole lenses, a grid part with elongated apertures all arranged in the same direction cannot be easily secured to alignment mandrels of circular cross section. As a result, grid movement during assembly can cause a misalignment that deteriorates the tube resolution. The present invention includes arranging circular and elongated apertures in the same grid part, and also alternately arranging circular and elongated apertures in adjacent grid parts, so as to secure the grid parts to the mandrels and automatically maintain the alignment during gun assembly. The aperture combinations described herein produce electron lens astigmatism of approximately the same strength and sign for each beam of an in-line gun.

Dependencies are inferred from the claim text.