Contrast enhancement filter for color CRT display devices

Abstract

A glass filter for contrast enhancement in a color CRT display devices comprises 100 parts by weight of a base glass comprising, in % by weight 3 to 70% SiO.sub.2, 0 to 40% B.sub.2 O.sub.3, 0 to 23% Al.sub.2 O.sub.3, 0 to 23% R.sub.2 O (R.sub.2 O being at least one selected from the group consisting of Li.sub.2 O, Na.sub.2 O and K.sub.2 O), 2 to 35% RO (RO being at least one selected from the group consisting of MgO, CaO, SrO, BaO, ZnO and PbO), 0 to 10% TiO.sub.2, 0 to 10% ZrO.sub.2, 0 to 35% La.sub.2 O.sub.3 and 5 to 40% Nd.sub.2 O.sub.3, at least two coloring components selected form the group consisting of 6 parts by weight or less CeO.sub.2, 1.0 parts by weight or less CuO, 3.5 parts by weight or less MnO.sub.2, 0.15 parts by weight or less CoO, 3.0 parts by weight or less Fe.sub.2 O.sub.3, 1.5 parts by weight or less NiO and 5.0 parts by weight or less Pr.sub.6 O.sub.11, and at least one coloring component selected form the group consisting of CeO, CuO, MnO.sub.2 and CoO.

Dependencies are inferred from the claim text.