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US4590405A
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Bivalent europium-activated barium aluminate phosphor and low mercury vapor discharge lamp provided with a phosphor
Assignee: US Philips Corp
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Filing: 1985-07-01
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Granted: 1986-05-20
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Expires: 2005-07-01
Abstract
Abstract A luminescent screen provided with a luminescent layer (4) disposed on a support (1) and containing an alkaline earth metal aluminate activated by bivalent europium. The alkaline earth metal is barium which may be replaced up to 25 mol. % by strontium. The aluminate has a crystal structure, the X-ray powder diagram of which corresponds or substantially corresponds to the diagram given in Table I of the description, while the ratio of alkaline earth metal to aluminium in the aluminate has a value of 1:5 to 1:10. An advantageous use of such a luminescent screen is found in low-pressure mercury vapor discharge lamps.
Inventors
- 👤 Gerardus P. F. Hoeks
- 👤 Marinus G. A. Tak
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 17:06
CPC Classifications
C; C09; C09K; C09K11/00; C09K11/08; C09K11/77; C09K11/7728; C09K11/7734; C09K11/7766; C09K11/7774; H; H01; H01J; H01J61/00; H01J61/02; H01J61/38; H01J61/42; H01J61/44
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
218 words
A luminescent screen provided with a luminescent layer which is dispersed on a support and contains an alkaline earth metal aluminate activated by bivalent europium, the alkaline earth metal being barium of which up to 25 mol.% may be replaced by strontium, characterized in that the aluminate has a crystal structure, the X-ray powder diagram of which corresponds at least substantially to the following X-ray powder diagram: ______________________________________
d(Å)
I d(Å)
I d(Å)
I
______________________________________
6.84 30 2.88 63 2.12 44
5.31 65 2.83 24 2.04 12
4.76 75 2.74 16 2.02 37
4.62 15 2.71 10 2.01 17
4.47 7 2.65 4 2.00 32
4.31 8 2.61 9 1.902 21
4.05 21 2.57 5 1.869 8
3.79 23 2.55 6 1.847 11
3.69 21 2.53 9 1.828 8
3.68 23 2.51 21 1.807 8
3.60 36 2.44 30 1.790 11
3.48 15 2.39 9 1.767 13
3.46 14 2.35 5 1.749 17
3.42 100 2.32 8 1.737 11
3.31 5 2.30 22 1.705 7
3.24 14 2.27 15 1.645 8
3.20 7 2.25 32 1.633 18
3.12 39 2.23 18 1.599 14
2.99 83 2.22 24 1.580 8
2.96 47 2.16 53 1.575 16
1.568 11
______________________________________ in which the molar ratio of the alkaline earth metal to aluminum in the aluminate is from 1:5 to 1:10.
Claim 2
Dependent Claim
218 words
A luminescent screen provided with a luminescent layer which is dispersed on a support and contains an alkaline earth metal aluminate activated by bivalent europium, the alkaline earth metal being barium of which up to 25 mol.% may be replaced by strontium, characterized in that the aluminate has a crystal structure, the X-ray powder diagram of which corresponds at least substantially to the following X-ray powder diagram: ______________________________________
d(Å)
I d(Å)
I d(Å)
I
______________________________________
6.84 30 2.88 63 2.12 44
5.31 65 2.83 24 2.04 12
4.76 75 2.74 16 2.02 37
4.62 15 2.71 10 2.01 17
4.47 7 2.65 4 2.00 32
4.31 8 2.61 9 1.902 21
4.05 21 2.57 5 1.869 8
3.79 23 2.55 6 1.847 11
3.69 21 2.53 9 1.828 8
3.68 23 2.51 21 1.807 8
3.60 36 2.44 30 1.790 11
3.48 15 2.39 9 1.767 13
3.46 14 2.35 5 1.749 17
3.42 100 2.32 8 1.737 11
3.31 5 2.30 22 1.705 7
3.24 14 2.27 15 1.645 8
3.20 7 2.25 32 1.633 18
3.12 39 2.23 18 1.599 14
2.99 83 2.22 24 1.580 8
2.96 47 2.16 53 1.575 16
1.568 11
______________________________________ in which the molar ratio of the alkaline earth metal to aluminum in the aluminate is from 1:5 to 1:10.
Claim 3
Dependent Claim
51 words
A luminescent screen as claimed in claim 1, characterized in that the aluminate has a composition defined by the formula Me 1-p Eu p Al q O 11/2 q+1, in which Me is barium with up to 25 mol.% of barium being replaceable by strontium and in which 0.005<p<0.25 and 5<q<10.
Claim 4
Dependent Claim
14 words
A luminescent screen as claimed in claim 2, characterized in that 0.02≦p≦0.10 and 7≦q≦9.
Claim 5
Dependent Claim
145 words
A method of preparing a luminescent alkaline earth metal aluminate activated by bivalent europium for use in a luminescent screen as claimed in claim 1, characterized in that a mixture is made of barium oxide, of which up to 25 mol.% may be replaced by strontium oxide, alumina and europium oxide or of compounds which are converted to these oxides on heating, the molar ratio of alkaline earth metal to aluminium is chosen to lie between 1:5 and 1:10, whilst there is added to this mixture boron oxide or a compound which is converted to boron oxide on heating in a quantity of 0.002 to 0.05 mole of boron per mole of aluminum, in that the mixture is heated in a weakly reducing atmosphere at a temperature of 1100° C. to 1400° C., and in that after cooling, the product obtained is washed with water.
Claim 6
Dependent Claim
16 words
A low-pressure mercury vapor discharge lamp provided with a luminescent screen as claimed in claim 1.
Claim 7
Dependent Claim
23 words
A lamp as claimed in claim 5, characterized in that the luminescent screen further comprises a green luminescing and a red luminescing substance.
Claim 8
Dependent Claim
33 words
A lamp as claimed in claim 6, characterized in that the green luminescing substance is a terbium-activated cerium magnesium aluminate and the red luminescing substance is an yttrium oxide activated by trivalent europium.
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) | 1989-05-19 | 1989-11-18 | 1990-05-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-05-19 | 1993-11-18 | 1994-05-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-05-19 | 1997-11-18 | 1998-05-20 | $7700.00 | Window Closed / Lapsed |