Focusing color-selection structure for a CRT

Claim 1

In a color-selection structure for a cathode-ray tube, said color-selection structure being of the type comprising (a) a metal plate having two opposed major surfaces and having an array of apertures therethrough, said apertures being arranged in substantially parallel columns, (b) an array of elongated electrical conductors closely spaced from said plate, the lengths of said conductors being substantially parallel to and interdigitated between said columns of apertures, and (c) connection means for applying a voltage between said plate and said array of conductors, the improvement wherein (1) said plate has an array of substantially-parallel ridges of plate metal between said columns of apertures and integral with and upstanding from one of said major surfaces, the lengths of said ridges being substantially parallel to said columns of apertures, said ridges being at least as high as said plate is thick, (2) an electrically-insulating layer over the tops of each of said ridges, and (3) an electrically-conducting layer over each said electrically-insulating layer, thereby providing said array of electrical conductors closely spaced from said plate.