Glass compositions for ophthalmic lenses
AssigneeHoya Glass Works, Ltd.
InventorHiroji Sagara
Life of this patent
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Abstract
A glass composition for an ophthalmic lens having a refractive index of at least 1.69, an Abbe value of at least 39 and a specific gravity of not more than 3.2 and comprising, in percent by weight: 1. 42 to 52 SiO.sub.2 +Al.sub.2 O.sub.3 +B.sub.2 O.sub.3 with 20 to 42 SiO.sub.2, 5 to 13 Al.sub.2 O.sub.3 and 0 to 20 B.sub.2 O.sub.3 ; 2. 22 to 39 CaO+MgO with 12 to 39 CaO and 0 to 20 MgO; 3. 15 to 28 ZrO.sub.2 +TiO.sub.2 +Nb.sub.2 O.sub.5 with 0 to 7 ZrO.sub.2, 5 to 13 TiO.sub.2 and 0 to 15 Nb.sub.2 O.sub.5 ; 4. 0 to 15 BaO+SrO+ZnO with 0 to 6 BaO, 0 to 10 SrO and 0 to 15 ZnO; and 5. 0 to 10 La.sub.2 O.sub.3 +Ta.sub.2 O.sub.5 +WO.sub.3 with 0 to 10 La.sub.2 O.sub.3, 0 to 6 Ta.sub.2 O.sub.5 and 0 to 10 WO.sub.3.
Claims4
A glass composition for an ophthalmic lens having a refractive index of at least 1.69, an Abbe value of at least 39 and a specific gravity of not more than 3.2 and consisting essentially of, in percent by weight:
- 1. 42 to 52 SiO.sub.2 +Al.sub.2 O.sub.3 +B.sub.2 O.sub.3 with 20 to 42 SiO.sub.2, 5 to 13 Al.sub.2 O.sub.3 and 0 to 20 B.sub.2 O.sub.3 ;
- 2. 22 to 39 CaO+MgO with 12 to 39 CaO and 0 to 20 MgO;
- 3. 15 to 28 ZrO.sub.2 +TiO.sub.2 +Nb.sub.2 O.sub.5 with 0 to 7 ZrO.sub.2, 5 to 13 TiO.sub.2 and 0 to 15 Nb.sub.2 O.sub.5 ;
- 4. 0 to 15 BaO+SrO+ZnO with 0 to 6 BaO, 0 to 10 SrO and 0 to 15 ZnO;
- and
- 5. 0 to 10 La.sub.2 O.sub.3 +Ta.sub.2 O.sub.5 +WO.sub.3 with 0 to 10 La.sub.2 O.sub.3, 0 to 6 Ta.sub.2 O.sub.5 and 0 to 10 WO.sub.3.
A glass composition for an ophthalmic lens having a refractive index of at least 1.69, an Abbe value of at least 39 and a specific gravity of not more than 3.2 and consisting essentially of, in percent by weight:
- 1. 40 to 52 SiO.sub.2 +Al.sub.2 O.sub.3 +B.sub.2 O.sub.3 with 20 to 52 SiO.sub.2, 0 to 13 Al.sub.2 O.sub.3 and 0 to 20 B.sub.2 O.sub.3 ;
- 2. 10 to 35 CaO+MgO with 1 to 35 CaO and 0 to 20 MgO;
- 3. 1 to 20 Li.sub.2 O+Na.sub.2 O+K.sub.2 O with 0 to 15 Li.sub.2 O and 0 to 15 Na.sub.2 O+K.sub.2 O;
- 4. 14 to 30 ZrO.sub.2 +TiO.sub.2 +Nb.sub.2 O.sub.5 with 0 to 11 ZrO.sub.2, 4 to 14 TiO.sub.2 and 0 to 20 Nb.sub.2 O.sub.5 ;
- 5. 0 to 15 BaO+SrO+ZnO with 0 to 8 BaO, 0 to 12 SrO and 0 to 15 ZnO;
- and
- 6. 0 to 15 La.sub.2 O.sub.3 +Ta.sub.2 O.sub.5 +WO.sub.3 with 0 to 12 La.sub.2 O.sub.3, 0 to 10 Ta.sub.2 O.sub.5 and 0 to 15 WO.sub.3.
Dependencies are inferred from the claim text.