US4446048A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Luminescent materials
Assignee: Thorn EMI Ltd
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Filing: 1981-11-23
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Granted: 1984-05-01
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Expires: 2001-11-23
Abstract
Abstract A phosphor for use in fluorescent lamps which comprises calcium sulphate and, optionally, up to 50% of strontium sulphate together with cerium (0.5-10%), manganese (up to 10%), an alkali metal (0.001 to 3%) and boron and/or aluminium (0.001 to 8%). The phosphor may be produced by blending and then firing the individual components. Tubes for use in the lamps may be electrostatically coated with the phosphor.
Inventors
- 👤 Peter W. Ranby
- 👤 David R. Palowkar
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 05:15
CPC Classifications
C; C09; C09K; C09K11/00; C09K11/08; C09K11/77; C09K11/7715; C09K11/7727; H; H01; H01J; H01J61/00; H01J61/02; H01J61/38; H01J61/42; H01J61/44
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
106 words
A phosphor for use in a fluorescent lamp which comprises an alkaline earth sulphate of which at least 50% of the alkaline earth of said alkaline earth sulphate is calcium but wherein up to 50% of the alkaline earth of said alkaline earth sulfate may be strontium, with the balance of said alkaline earth being calcium, and which additionally contains the following percentages by weight of the alkaline earth sulphate (a) from 0.5 to 10 of cerium, (b) up to 10 of manganese, (c) from 0.001 to 3 of an alkali metal selected from lithium, sodium and potassium, and (d) from 0.001 to 8 of boron.
Claim 2
Dependent Claim
106 words
A phosphor for use in a fluorescent lamp which comprises an alkaline earth sulphate of which at least 50% of the alkaline earth of said alkaline earth sulphate is calcium but wherein up to 50% of the alkaline earth of said alkaline earth sulfate may be strontium, with the balance of said alkaline earth being calcium, and which additionally contains the following percentages by weight of the alkaline earth sulphate (a) from 0.5 to 10 of cerium, (b) up to 10 of manganese, (c) from 0.001 to 3 of an alkali metal selected from lithium, sodium and potassium, and (d) from 0.001 to 8 of boron.
Claim 3
Dependent Claim
11 words
A phosphor according to claim 1 whenever of orthorhombic crystal structure.
Claim 4
Dependent Claim
17 words
A phosphor according to claim 1 wherein the alkaline earth sulphate consists of calcium and strontium sulfate.
Claim 5
Dependent Claim
15 words
A phosphor according to claim 1 wherein the alkaline earth sulphate consists of calcium sulphate.
Claim 6
Dependent Claim
21 words
A phosphor according to claim 1 which contains from 1% to 8% by weight of the alkaline earth sulphate of cerium.
Claim 7
Dependent Claim
21 words
A phosphor according to claim 1 which contains from 1% to 8% by weight of the alkaline earth sulphate of manganese.
Claim 8
Dependent Claim
10 words
A phosphor according to claim 1 which contains no manganese.
Claim 9
Dependent Claim
22 words
A phosphor according to claim 1 which contains from 0.1% to 3% by weight of the alkaline earth sulphate of alkali metal.
Claim 10
Dependent Claim
12 words
A phosphor according to claim 1 wherein the alkali metal is lithium.
Claim 11
Dependent Claim
21 words
A phosphor according to claim 9 which contains from 0.001% to 0.5% by weight of the alkaline earth sulphate of lithium.
Claim 12
Dependent Claim
21 words
A phosphor according to claim 1 which contains from 0.001% to 0.5% by weight of the alkaline earth sulphate of boron.
Claim 13
Dependent Claim
21 words
A phosphor according to claim 1 which contains from 0.1% to 8% by weight of the alkaline earth sulphate of boron.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-05-01 | 1987-10-31 | 1988-05-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-05-01 | 1991-10-31 | 1992-05-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-05-01 | 1995-10-31 | 1996-05-01 | $7700.00 | Window Closed / Lapsed |