US3713827A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the development of photographic material
Assignee: Agfa Gevaert NV
•
Filing: 1970-10-07
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Granted: 1973-01-30
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Expires: 1990-10-07
Abstract
Abstract A METHOD OF DEVELOPING EXPOSED PHOTOGRAPHIC SILVER HALIDE ELEMENTS IS DESCRIBED ACCORDING TO WHICH AN AQUEOUS ALKALINE COMPOSITION IS USED IN THE PRESENCE OF AN ANIONIC SILVER HALIDE DEVELOPING AGENT AND A DIQUATERNARY CYCLIC AMMONIUM SALT WHICH BY THE UPTAKE OF 1 ELECTRON FORMS STABLE WEITZ RADICALS. THE DIQUATERNARY CYCLIC AMMONIUM SALTS ACCELERATE DEVELOPMENT AND THE DEVELOPMENT ACCELERATING EFFECT SURPASSES THAT OF RELATED QUATERNNARY AMMONIUM COMPOUNDS THAT DO NOT FORM STABLE WEITZ RADICALS.
Inventors
- 👤 J Willems
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 11:56
CPC Classifications
C; C07; C07D; C07D487/00; C07D487/02; C07D487/04; C07D513/00; C07D513/02; C07D513/04; G; G03; G03C; G03C5/00; G03C5/26; G03C5/29; G03C5/305; 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) | 1976-01-30 | 1976-07-31 | 1977-01-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-30 | 1980-07-31 | 1981-01-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-30 | 1984-07-31 | 1985-01-30 | $7700.00 | Window Closed / Lapsed |