US3740221A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Development of photographic material
Assignee: Agfa Gevaert NV
•
Filing: 1970-10-07
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Granted: 1973-06-19
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Expires: 1990-10-07
Abstract
Abstract A METHOD OF DEVELOPING LIGHT-SENSITIVE SILVER HALIDE ELEMENTS IS DESCRIBED WHEREBY THE ELEMENTS ARE TREATED AFTER EXPOSURE WITH AN AQUEOUS ALKALI COMPOSITION IN THE PRESENCE OF A HYDROXYLAMINE DEVELOPING AGENT AND A 1-ARYL-3-PRAZOLIDINONE COMPOUND OF THE FORMULA: R1-N<(-CH(-R4)-C(-R3)(-R2)-CO-NH-) WHEREIN R1 IS ARYL, R2 AND R3 ARE HYDROGEN, ALKYL, ARALKYL OR ARYL, AND R4 IS HYDROGEN, ALKYL, ALKOXY, ARALKOXY OR ARYLOXY. THE 1-ARYL-3-PYRAZOLIDINONE COMPOUND EXHIBITS A SUPERADDITIVE EFFECT ON THE HYDROXYLAMINE DEVELOPING AGENT.
Inventors
- 👤 J Willems
- 👤 P Schots
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 02:01
CPC Classifications
G; G03; G03C; G03C8/00; G03C8/02; G03C8/04; G03C8/06
Claims Analysis
Total Claims: 0
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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) | 1976-06-18 | 1976-12-18 | 1977-06-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-18 | 1980-12-18 | 1981-06-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-18 | 1984-12-18 | 1985-06-19 | $7700.00 | Window Closed / Lapsed |