US3843550A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photochromic composition
Assignee: Saint Gobain Industries SA
•
Filing: 1968-10-23
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Granted: 1974-10-22
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Expires: 1988-10-23
Abstract
Abstract 1. A LIGHT-SENSITIVE COMPOSITION INCLUDING AS THE ESSENTIAL PHOTOCHROMIC SENSITIVE ELEMENT 1,3,3, TRIMETHYL INDOLINO-2-SPIRO-2''-METHYL-8''-CUMARINO (7,8,B) PYRAN.
Inventors
- 👤 A Hinnen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 13:10
CPC Classifications
C; C07; C07D; C07D491/00; C07D491/12; C07D491/20; G; G03; G03C; G03C1/00; G03C1/685
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
15 words
A LIGHT-SENSITIVE COMPOSITION INCLUDING AS THE ESSENTIAL PHOTOCHROMIC SENSITIVE ELEMENT 1,3,3, TRIMETHYL INDOLINO-2-SPIRO-2''-METHYL-8''-CUMARINO (7,8,B) PYRAN.
Claim 2
Dependent Claim
15 words
A LIGHT-SENSITIVE COMPOSITION INCLUDING AS THE ESSENTIAL PHOTOCHROMIC SENSITIVE ELEMENT 1,3,3, TRIMETHYL INDOLINO-2-SPIRO-2''-METHYL-8''-CUMARINO (7,8,B) PYRAN.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-10-21 | 1978-04-22 | 1978-10-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-21 | 1982-04-22 | 1982-10-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-21 | 1986-04-22 | 1986-10-22 | $7700.00 | Window Closed / Lapsed |