Patent ID: 6844669
Filing Date: 2005-01-18
Classification: C03C,H01J

Abstract:
1. A glass funnel for a cathode ray tube, which has a substantially rectangular opened end at one end and a neck portion at the other end and which constitutes, together with a glass panel having a substantially rectangular face portion, a glass bulb to be used for a cathode ray tube, wherein the glass constituting the glass funnel contains, by molar percentage, at least 60% of SiO 2 and at least 7% of PbO; when the molar percentages of Na 2 O and K 2 O contained in said glass are represented by WNa and WK, respectively, 0.35≦WK/(WNa+WK)≦0.6; a compressive stress layer is formed by chemical tempering at least in the outer surface of a region containing a position where the tensile stress formed when the interior of the glass bulb is vacuumed to produce the cathode ray tube, becomes maximum; and either one or both of the outer surface of the chemically tempered region and the inner surface opposite to said outer surface, are colored by ion exchange coloration.