Patent US4072490A successfully refreshed from Google Patents.
US4072490A
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Apparatus and process for producing a gradient photochromic ophthalmic lens
Assignee: Corning Glass Works
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Filing: 1976-11-08
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Granted: 1978-02-07
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Expires: 1996-11-08
Abstract
Abstract A gradient photochromic ophthalmic lens blank is produced by heat treating an ophthalmic lens blank composed of potentially photochromic glass at a temperature sufficient to develop photochromic properties therein, while maintaining in proximity to a portion of the lens blank a metal heat sink with a specified heat absorbing capacity. The metal heat sink acts to provide a temperature gradient across the ophthalmic lens blank during heating, which gradient is effective to provide a gradient in photochromic properties thereacross.
Inventors
- 👤 Edwin J. Illig
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 19:38
CPC Classifications
C; C03; C03C; C03C4/00; C03C4/04; C03C4/06; C03B; C03B32/00
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
101 words
A process for manufacturing a gradient photochromic ophthalmic lens blank which comprises the steps of: (a) subjecting an ophthalmic lens blank composed of a potentially photochromic glass to a heat treatment at a temperature sufficient to develop photochromic properties in said glass, while (b) maintaining a selected portion of the ophthalmic lens blank in proximity to a solid metal heat sink having a heat capacity of at least about 15 calories ° C -1 ; said metal heat sink acting to provide a temperature gradient across the ophthalmic lens blank which is effective to provide a gradient in photochromic properties thereacross.
Claim 2
Dependent Claim
101 words
A process for manufacturing a gradient photochromic ophthalmic lens blank which comprises the steps of: (a) subjecting an ophthalmic lens blank composed of a potentially photochromic glass to a heat treatment at a temperature sufficient to develop photochromic properties in said glass, while (b) maintaining a selected portion of the ophthalmic lens blank in proximity to a solid metal heat sink having a heat capacity of at least about 15 calories ° C -1 ; said metal heat sink acting to provide a temperature gradient across the ophthalmic lens blank which is effective to provide a gradient in photochromic properties thereacross.
Claim 3
Dependent Claim
34 words
A process in accordance with claim 1 wherein the metal heat sink is composed of a metal having a volume heat capacity of at least about 0.8 calories cm -3 ° C -1 .
Claim 4
Dependent Claim
19 words
A process in accordance with claim 1 wherein the metal heat sink is composed at least predominantly of iron.
Claim 5
Dependent Claim
104 words
Lens treating apparatus for producing a gradient photochromic ophthalmic lens blank which comprises: (a) a cylindrical open-bottomed step-ring former cup, said former cup having a circular wall which includes a circumferential step therein; (b) a ceramic former positioned within the step-ring former cup and edge-supported by the circumferential step, said ceramic former being suitable for supporting a potentially photochromic ophthalmic lens blank; (c) a cast iron heat sink of semicircular cross-section positioned against the circular wall of the former cup and immediately beneath the ceramic former, said cast iron heat sink having a heat capacity of at least 15 calories ° C -1 .
Claim 6
Dependent Claim
104 words
Lens treating apparatus for producing a gradient photochromic ophthalmic lens blank which comprises: (a) a cylindrical open-bottomed step-ring former cup, said former cup having a circular wall which includes a circumferential step therein; (b) a ceramic former positioned within the step-ring former cup and edge-supported by the circumferential step, said ceramic former being suitable for supporting a potentially photochromic ophthalmic lens blank; (c) a cast iron heat sink of semicircular cross-section positioned against the circular wall of the former cup and immediately beneath the ceramic former, said cast iron heat sink having a heat capacity of at least 15 calories ° C -1 .
References Cited (Backward Citations)
GB877242A
Cited
US3250246A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-02-06 | 1981-08-08 | 1982-02-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-02-06 | 1985-08-08 | 1986-02-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-02-06 | 1989-08-08 | 1990-02-07 | $7700.00 | Window Closed / Lapsed |