Patent US2500421A successfully refreshed from Google Patents.
US2500421A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photographic silver halide transfer process
Assignee: Polaroid Corp
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Filing: 1944-11-03
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Granted: 1950-03-14
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Expires: 1964-11-03
Abstract
No abstract record available.
Inventors
- 👤 Edwin H Land
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 17:58
CPC Classifications
G; G03; G03C; G03C8/00; G03C8/32; G03C8/34; G03C8/42; G03C8/44
Claims Analysis
Total Claims: 1
Claim 1
Independent Claim
311 words
THE PROCESS OF FORMING A POSITIVE IMAGE WHICH COMPRISES DEVELOPING A LATENT NEGATIVE IMAGE IN A PHOTOSENSITIVE LAYER COMPRISING A SILVER HALIDE EMULSION BY SUBSTANTIALLY UNIFORMLY DISTRIBUTING THROUGHOUT SAID PHOTOSENSIVE LAYER WHILE EXCLUDING ACTINIC LIGHT THEREFORM AN ALKALINE LIQUID REAGENT COMPRISING A PHOTOGRAPHIC DEVELOPER AND A SILVER HALIDE SOLVENT WHICH FORMS A SOLUBLE AND REDUCIBLE SILVER COMPLEX WITH UNEXPOSED SILVER HALIDE AND PROVIDING IN SAID PHOTOSENSITIVE LAYER DEVELOPED SILVER AND, IN SOLUTION IN SAID LIQUID REAGENT, A TRANSFERABLE IMAGEWISE DISTRIBUTION OF SILVER COMPLEX; TRANSFERRING FROM SAID PHOTOSENSITIVE LAYER, BY IMBITUTION AND WHILE PREVENTING ACCESS OF ACTINIC LIGHT TO SAID PHOTOSENSITIVE LAYER, AT LEAST PART OF SAID IMAGEWISE DISTRIBUTION OF SAID SILVER COMPLEX TO AN IMAGERECEIVING LAYER SUPERPOSED WITH RESPECT TO SAID PHOTOSENSITIVE LAYER IN SUCH CLOSE PROXIMITY AS TO RECEIVE A DEPTHWISE DIFFUSION OF LIQUID FROM SAID PHOTOSENSITIVE LAYER WITHOUT APPRECIABLY DISTURBING THE IMAGEWISE DISTRIBUTION OF SAID DISSOLVED SILVER COMPLEX IN SAID LIQUID REAGENT; WHILE STILL EXCLUDING ACTINIC LIGHT FROM SAID PHOTOSENSITIVE LAYER AND WITHOUT DISTURBING SAID CLOSE PROXIMITY OF SAID EMULSION LAYER TO SAID IMAGE-RECIVING LAYER, DEVELOPING WITH SAID DEVELOPER THE SILVER OF SAID COMPLEX IN SAID IMAGE-RECEIVING LAYER WHEREBY TO PROVIDE A POSITIVE IMAGE IN SILVER OF SAID LATENT IMAGE, SAID SILVER HALIDE BEING IN EXCESS OF THAT WHICH IS TRANSFORMED TO SAID COMPLEX BY SAID SILVER HALIDE SOLVENT AND SAID DEVELOPER BEING IN EXCESS OF THAT REQUIRED TO DEVELOP THE SILVER IMAGES IN BOTH SAID PHOTOSENSITIVE LAYER AND SAID RECEIVING LAYER; SUBSTANTIALLY UNIFORMLY EXPOSING SAID PHOTOSENSITIVE LAYER TO ACTINIC LIGHT; RETAINING SAID PHOTOSENSITIVE LAYER AND SAID IMAGE-RECEIVING LAYERS IN SAID SUPERPOSED RELATION TO PERMIT DEVELOPER TO BE ACCUMULATED IN SAID PHOTOSENSITIVE LAYER BY INHIBITION AND TO AT LEAST PARTIALLY DEVELOP SILVER HALIDE THEREIN WHICH HAS BEEN FOGGED BY SAID UNIFORM EXPOSURE WHEREBY SAID ACCUMULATED EXCESS DEVELOPER IS OXIDIZED; AND THEN SEPARATING SAID IMAGE-RECEIVING LAYER FROM SAID PHOTOSENSITIVE LAYER.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1953-03-13 | 1953-09-12 | 1954-03-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1957-03-13 | 1957-09-12 | 1958-03-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1961-03-13 | 1961-09-12 | 1962-03-14 | $7700.00 | Window Closed / Lapsed |