Intermediate sub-assembly for use in making color picture tubes

Claim 1

An intermediate sub-assembly for use in the formation of a multi-component phosphor screen by an optical exposure process wherein a shadow mask extends between said phosphor screen and a source of actinic radiation, for use in a color cathode-ray tube, which sub-assembly comprises: a shadow mask having a plurality of apertures disposed in a predetermined array corresponding to that of the individual phosphor components of said screen, with the apertures individually of a corresponding shape but of larger size than such individual phosphor components; and a sheet of transparent plastic material overlying said aperture array and in broad surfacE contact with the phosphor screen side of said shadow mask, the portion of said sheet which overlies each of said apertures being configured to constitute an optical focusing lens to provide for optical exposure through said mask of image screen areas smaller than said apertures, said optical focusing lenses being doubleconvex with each side having a different radius of curvature, and in which the smaller radius of curvature is on the side of sheet which contacts the shadow mask.