US3919108A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of preventing degradation of yttrium oxide phosphor
Assignee: Westinghouse Electric Corp
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Filing: 1974-11-14
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Granted: 1975-11-11
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Expires: 1994-11-14
Abstract
Abstract A method of preventing degradation of yttrium oxide phosphor in an aqueous slurry containing photosensitive chromate ion. An ammonium polycarboxylate compound is added to the slurry to retard or eliminate chromate absorption by the phosphor.
Inventors
- 👤 Harold D Wilcox
- 👤 Douglas A Griswold
- 👤 Himanshu M Patel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 18:40
CPC Classifications
C; C09; C09K; C09K11/00; C09K11/08; C09K11/77; C09K11/7701
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
52 words
METHOD OF PREVENTING DEGRADATION OF YTTRIUM OXIDE PHOSPHOR IN AN AQUEOUS SLURRY CONTAINING DICHROMATE ION, WHICH METHOD COMPRISES ADDING AN AMMONIUM POLYCARBOXYLATE SELECTED FROM THE GROUP CONSISTING OF A AMMONIUM OXALATE, AMMONIUM CITRATE AND AMMONIUM TARTRATE IN AN AMOUNT OF AT LEAST 0.5 WEIGHT PERCENT OF THE PHOSPHOR WEIGHT, TO THE SLURRY.
Claim 2
Dependent Claim
52 words
METHOD OF PREVENTING DEGRADATION OF YTTRIUM OXIDE PHOSPHOR IN AN AQUEOUS SLURRY CONTAINING DICHROMATE ION, WHICH METHOD COMPRISES ADDING AN AMMONIUM POLYCARBOXYLATE SELECTED FROM THE GROUP CONSISTING OF A AMMONIUM OXALATE, AMMONIUM CITRATE AND AMMONIUM TARTRATE IN AN AMOUNT OF AT LEAST 0.5 WEIGHT PERCENT OF THE PHOSPHOR WEIGHT, TO THE SLURRY.
Claim 3
Dependent Claim
31 words
The method specified in claim 1, wherein said slurry includes polyvinyl alcohol and the polycarboxylate is ammonium oxalate in an amount of about one percent by weight of the phosphor weight.
Claim 4
Dependent Claim
24 words
The method specified in claim 1, wherein a pH level of between 9 and 9.5 is maintAined by adding ammonium hydroxide to the slurry.
References Cited (Backward Citations)
US2647066A
Cited
US3522071A
Cited
US3707396A
Cited
US3615571A
Cited
US3619265A
Cited
US3594207A
Cited
US3607371A
Cited
US3690929A
Cited
US3684546A
Cited
US3676177A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-11-10 | 1979-05-12 | 1979-11-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-10 | 1983-05-12 | 1983-11-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-10 | 1987-05-12 | 1987-11-11 | $7700.00 | Window Closed / Lapsed |