US4211569A
Expired / Lapsed
US
⏱️ 0.0 years remaining
High index ophthalmic glasses
Assignee: Corning Glass Works
•
Filing: 1979-03-09
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Granted: 1980-07-08
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Expires: 1999-03-09
Abstract
Abstract This invention is concerned with the production of glasses suitable for use as segments in multifocal ophthalmic lenses and, especially, as segments in multifocal photochromic ophthalmic lenses. The glasses have refractive indices between about 1.58-1.71, softening points between 620°-645° C., strain points between 445°-480° C., coefficients of thermal expansion (0°-300° C.) between 60-66×10 -7 /°C., excellent chemical durability, and consist essentially, in weight percent on the oxide basis, of 0-2% Li 2 O and/or 0-3% Na 2 O, 1-4% Li 2 O+Na 2 O, 4-9% BaO, 25-50% PbO, 4-8% B 2 O 3 , 4-7% Al 2 O 3 , 30-50% SiO 2 , and 0.5-3% TiO 2 .
Inventors
- 👤 George B. Hares
- 👤 David L. Morse
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 08:48
CPC Classifications
C; C03; C03C; C03C3/00; C03C3/04; C03C3/076; C03C3/102; C03C3/108; C03C3/062; C03C3/07; C03C3/072; Y; Y10; Y10S; Y10S501/00; Y10S501/90
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
132 words
An ophthalmic glass having a refractive index between about 1.58-1.71, a softening point between 620°-645° C., a strain point between 445°-480° C., a coefficient of thermal expansion (0°-300° C.) between 61.3-65.6×10 -7 /°C., and a weight loss of no more than 0.03 mg/cm 2 with no visible surface imperfection after immersion into a 10% by weight aqueous solution of HCl for 10 minutes at 25° C., said glass consisting essentially, in weight percent on the oxide basis, of 0-2% Li 2 O, 0-3% Na 2 O, 1-4% Li 2 O+Na 2 O, 4-9% BaO, 25-50% PbO, 4-8% B 2 O 3 , 4-7% Al 2 O 3 , 30-50% SiO 2 , and 0.5-3% TiO 2 , the sum of those constituents constituting at least 95% by weight of the total composition.
Claim 2
Dependent Claim
132 words
An ophthalmic glass having a refractive index between about 1.58-1.71, a softening point between 620°-645° C., a strain point between 445°-480° C., a coefficient of thermal expansion (0°-300° C.) between 61.3-65.6×10 -7 /°C., and a weight loss of no more than 0.03 mg/cm 2 with no visible surface imperfection after immersion into a 10% by weight aqueous solution of HCl for 10 minutes at 25° C., said glass consisting essentially, in weight percent on the oxide basis, of 0-2% Li 2 O, 0-3% Na 2 O, 1-4% Li 2 O+Na 2 O, 4-9% BaO, 25-50% PbO, 4-8% B 2 O 3 , 4-7% Al 2 O 3 , 30-50% SiO 2 , and 0.5-3% TiO 2 , the sum of those constituents constituting at least 95% by weight of the total composition.
Claim 3
Dependent Claim
22 words
A glass according to claim 1 also containing up to 3% La 2 O 3 and/or up to 2% ZrO 2 .
Claim 4
Dependent Claim
56 words
A glass according to claim 1 having a coefficient of expansion of 61.8×10 -7 /°C. with the following approximate composition in parts by weight on the oxide basis: ______________________________________
SiO.sub.2 46.38
PbO 27.19
B.sub.2 O.sub.3 7.30
Al.sub.2 O.sub.3 6.39
BaO 8.00
Na.sub.2 O 2.65
Li.sub.2 O 1.24
TiO.sub.2 0.60
Sb.sub.2 O.sub.3 0.10
As.sub.2 O.sub.3 0.15
______________________________________
Claim 5
Dependent Claim
54 words
A glass according to claim 1 having a coefficient of expansion of 61.3×10 -7 /°C. with approximate composition in parts by weight on the oxide basis: ______________________________________
SiO.sub.2 40.60
PbO 35.80
B.sub.2 O.sub.3 6.60
Al.sub.2 O.sub.3 6.20
BaO 6.50
Na.sub.2 O 2.10
Li.sub.2 O 0.70
TiO.sub.2 0.87
Sb.sub.2 O.sub.3 0.2
As.sub.2 O.sub.3 0.2
______________________________________
Claim 6
Dependent Claim
56 words
A glass according to claim 1 having a coefficient of expansion of 62×10 -7 /°C. with the following approximate composition in parts by weight on the oxide basis: ______________________________________
SiO.sub.2
35.62
PbO 44.40
B.sub.2 O.sub.3
5.93
Al.sub.2 O.sub.3
6.00
BaO 5.00
Na.sub.2 O
1.50
Li.sub.2 O
0.15
TIO.sub.2
1.15
Sb.sub.2 O.sub.3
0.10
As.sub.2 O.sub.3
0.15
______________________________________
Claim 7
Dependent Claim
61 words
A glass according to claim 1 having a coefficient of expansion of 65.6×10 -7 /°C. with the following approximate composition in parts by weight on the oxide basis: ______________________________________
SiO.sub.2
31.27
PbO 44.42
B.sub.2 O.sub.3
5.36
Al.sub.2 O.sub.3
4.65
BaO 8.00
Na.sub.2 O
0.95
Li.sub.2 O
0.15
TiO.sub.2
2.80
La.sub.2 O.sub.3
1.65
ZrO.sub.2
0.50
Sb.sub.2 O.sub.3
0.10
As.sub.2 O.sub.3
0.15
______________________________________
References Cited (Backward Citations)
US3973976A
Cited
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1983-07-08 | 1984-01-07 | 1984-07-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-07-08 | 1988-01-07 | 1988-07-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-07-08 | 1992-01-07 | 1992-07-08 | $7700.00 | Window Closed / Lapsed |