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Patent US3764554A successfully refreshed from Google Patents.
US3764554A
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Luminescent alkaline earth sulfate phosphor and method of preparation
Assignee: US Philips Corp
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Filing: 1970-11-13
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Granted: 1973-10-09
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Expires: 1990-11-13
Abstract
Abstract An ultraviolet bivalent europium activated alkaline earth sulfate phosphor useful for low-pressure mercury vapor discharge lamps and cathode-ray tubes.
Inventors
- 👤 R Schuil
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 09:49
CPC Classifications
C; C09; C09K; C09K11/00; C09K11/08; C09K11/77; C09K11/7728; C09K11/7741
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
15 words
The phosphor of claim 1 wherein 0.01 < or = p < or = 0.08.
Claim 2
Independent Claim
159 words
A method of manufacturing an ultraviolet luminescent alkaline earth sulfate phosphor of the formula: SrxBayCazEup2 SO4 in which Eu2 represents bivalent europium and in which x + y + z + p 1 0 < or = x < or = 1 0 < or = y < or = 1 0 < or = z < or = 0.75 and 0.001 < or = p < or = 0.20 comprising dissolving in water at least one alkaline earth salt selected from the group consisting of water-soluble strontium, calcium and barium salts together with a water-soluble europium salt, the anions of said salts being non-reducible by zinc, passing the resultant solution through a column of amalgamated zinc, then adding said solution to diluted sulfuric acid thereby precipitating the desired bivalent europium-activated alkaline earth phosphate, filtering and washing said precipitate and then heating said precipitate in a closed crucible for 1-5 hours at a temperature of between 800* and 1,200*C.
Claim 3
Dependent Claim
32 words
A method as claimed in claim 3, characterized in that the precipitate is heated in the presence of 0.5 - 200 percent by weight of NaCl calculated on the quantity of precipitate.
References Cited (Backward Citations)
US3650976A
Cited
US3669897A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-10-08 | 1977-04-09 | 1977-10-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-08 | 1981-04-09 | 1981-10-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-08 | 1985-04-09 | 1985-10-09 | $7700.00 | Window Closed / Lapsed |