Multipurpose photochromic brown glasses

Claim 2

A composition for a photochromic glass consisting essentially of, in approximate calculated weight percent, about: ______________________________________ SiO.sub.2 54-58% Ag 0.18-0.33% B.sub.2 O.sub.3 18-22% Cl 0.25-0.50% Al.sub.2 O.sub.3 7-8% Br 0.04-0.12% Li.sub.2 O 3.75-4.5% CuO 0.007-0.012% Na.sub.2 O 0-1% PbO 0-0.08% K.sub.2 O 5.5-7.5% Sb.sub.2 O.sub.3 0-0.20% TiO.sub.2 0-2% Pd 1-6 ppm ZrO.sub.2 2-4.5% ______________________________________ plus 0-1.0% Er 2 O 3 and/or 0-10 ppm Au, the mole ratio of Li 2 O:Na 2 O being equal to or greater than 9:1 and the glass having a coloration in the fully darkened state corresponding to chromaticity coordinates, in accordance with the 1931 C.I.E. trichromatic colorimetric system, that fall within the trapezoid ABCDA in the drawing for a 1.1 mm glass thickness, and within the trapezoid EFGHE for a 2 mm glass thickness.

Claim 3

A composition in accordance with claim 1 wherein the glass contains 0-1% Er 2 O 3 .

Claim 4

A composition in accordance with claim 1 wherein the glass contains 0-10 ppm Au.

Claim 5

A composition in accordance with claim 1 wherein the Ag content is 0.20-0.33% and the Cl content is 0.30-0.50%.

Claim 6

A composition in accordance with claim 1 wherein the Pd content is 2-4 ppm.

Claim 7

A composition in accordance with claim 1 consisting approximately of: ______________________________________ SiO.sub.2 54.5 B.sub.2 O.sub.3 20.4 Al.sub.2 O.sub.3 7.3 Li.sub.2 O 4.3 Na.sub.2 O 0.8 K.sub.2 O 6.0 TiO.sub.2 1.0 ZrO.sub.2 4.7 Ag 0.25 CuO 0.008 PbO 0.03 Sb.sub.2 O.sub.3 0.01 Br 0.11 Cl 0.36 Pd 3 ppm. ______________________________________

Claim 8

A photochromic glass lens having a glass composition . consisting essentially of, in approximate calculated weight percent, about: ______________________________________ SiO.sub.2 54-58% Ag 0.18-0.33% B.sub.2 O.sub.3 18-22% Cl 0.25-0.50% Al.sub.2 O.sub.3 7-8% Br 0.04-0.12% Li.sub.2 O 3.75-4.5% CuO 0.007-0.012% Na.sub.2 O 0-1% PbO 0-0.08% K.sub.2 O 5.5-7.5% Sb.sub.2 O.sub.3 0-0.20% TiO.sub.2 0-2% Pd 1-6 ppm ZrO.sub.2 2-4.5% ______________________________________ plus 0-1.0% Er 2 O 3 and/or 0-10 ppm Au, the mole ratio of Li 2 O:Na 2 O being equal to or greater than 9:1 and the glass having a coloration in the fully darkened state corresponding to chromaticity coordinates, in accordance with the 1931 C.I.E. trichromatic colorimetric system, that fall within the trapezoid ABCDA in the drawing for a 1.1 mm glass thickness, and within the trapezoid EFGHE for a 2 mm glass thickness.

Claim 9

A photochromic glass lens having a glass composition . consisting essentially of, in approximate calculated weight percent, about: ______________________________________ SiO.sub.2 54-58% Ag 0.18-0.33% B.sub.2 O.sub.3 18-22% Cl 0.25-0.50% Al.sub.2 O.sub.3 7-8% Br 0.04-0.12% Li.sub.2 O 3.75-4.5% CuO 0.007-0.012% Na.sub.2 O 0-1% PbO 0-0.08% K.sub.2 O 5.5-7.5% Sb.sub.2 O.sub.3 0-0.20% TiO.sub.2 0-2% Pd 1-6 ppm ZrO.sub.2 2-4.5% ______________________________________ plus 0-1.0% Er 2 O 3 and/or 0-10 ppm Au, the mole ratio of Li 2 O:Na 2 O being equal to or greater than 9:1 and the glass having a coloration in the fully darkened state corresponding to chromaticity coordinates, in accordance with the 1931 C.I.E. trichromatic colorimetric system, that fall within the trapezoid ABCDA in the drawing for a 1.1 mm glass thickness, and within the trapezoid EFGHE for a 2 mm glass thickness.

Claim 10

A lens in accordance with claim 7 wherein the lens thickness is about 1.1 mm and the chromaticity coordinates fall within the trapezoid ABCDA in the drawing.

Claim 11

A lens in accordance with claim 7 wherein the lens thickness is about 2 mm and the chromaticity coordinates fall within the trapezoid EFGHE in the drawing.

Claim 12

A laminated, glass-plastic, ophthalmic lens wherein the glass element has a composition consisting essentially of, in approximate calculated weight percent, about ______________________________________ SiO.sub.2 54-58% B.sub.2 O.sub.3 18-22% Al.sub.2 O.sub.3 7-8% Li.sub.2 O 3.75-4.5% Na.sub.2 O 0-1% K.sub.2 O 5.5-7.5% TiO.sub.2 0-2% ZrO.sub.2 2-4.5% Ag 0.20-0.33% Cl 0.30-0.50% Br 0.04-0.12% CuO 0.007-0.012% PbO 0-0.08% Sb.sub.2 O.sub.3 0-0.20% Pd 1-6 ppm ______________________________________ plus 0-1.0% Er 2 O 3 and/or 0-10 ppm Au, the mole ratio of Li 2 O:Na 2 O being equal to or greater than 9:1 and the glass having a coloration in the fully darkened state corresponding to chromaticity coordinates, in accordance with the 1931 C.I.E. trichromatic colorimetric system, that fall within the trapezoid ABCDA in the drawing for a 1.1 mm glass thickness.

Claim 13

A laminated, glass-plastic, ophthalmic lens wherein the glass element has a composition consisting essentially of, in approximate calculated weight percent, about ______________________________________ SiO.sub.2 54-58% B.sub.2 O.sub.3 18-22% Al.sub.2 O.sub.3 7-8% Li.sub.2 O 3.75-4.5% Na.sub.2 O 0-1% K.sub.2 O 5.5-7.5% TiO.sub.2 0-2% ZrO.sub.2 2-4.5% Ag 0.20-0.33% Cl 0.30-0.50% Br 0.04-0.12% CuO 0.007-0.012% PbO 0-0.08% Sb.sub.2 O.sub.3 0-0.20% Pd 1-6 ppm ______________________________________ plus 0-1.0% Er 2 O 3 and/or 0-10 ppm Au, the mole ratio of Li 2 O:Na 2 O being equal to or greater than 9:1 and the glass having a coloration in the fully darkened state corresponding to chromaticity coordinates, in accordance with the 1931 C.I.E. trichromatic colorimetric system, that fall within the trapezoid ABCDA in the drawing for a 1.1 mm glass thickness.