Method of manufacturing reproduction masks for producing a pattern of elongate apertures in a shadow mask of a color cathode ray tube

摘要

A method of manufacturing a pair of associated reproduction masks for manufacturing shadow masks for display tubes. In order to obtain elongate apertures which are enlarged in width on the side of the mask facing the screen, the second reproduction mask is formed by reproducing the first reproduction mask on a photographic plate by means of light rays which have a substantially greater divergence in a plane perpendicular to the long dimension of the apertures than in the plane parallel thereto.