US4806825A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Infra-red phosphors
Assignee: EMI Group Ltd
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Filing: 1988-05-19
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Granted: 1989-02-21
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Expires: 2008-05-19
Abstract
Abstract A phosphor comprises a chromium activated alkaline earth aluminate having a hexagonal crystal structure and incorporates divalent europium as a sensitizer. The phosphor may also incorporate one or more of divalent manganese and/or zinc and/or magnesium. Such a phosphor emits in the infra-red.
Inventors
- 👤 Colin L. R. Catherall
- 👤 Martin J. Fuller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 16:37
CPC Classifications
H; H01; H01J; H01J61/00; H01J61/02; H01J61/38; H01J61/42; H01J61/44; C; C09; C09K; C09K11/00; C09K11/08; C09K11/77; C09K11/7728; C09K11/7734
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
149 words
A trivalent chromium activated alkaline earth aluminate phosphor having a hexagonal crystal structure and divalent europium and optionally one or more of divalent manganese and zinc incorporated therein, and emitting in the region of the electromagnetic spectrum between 650 and 800 nm, having a composition represented by: (A.sub.(w-y) B.sub.x Eu.sub.y Cr.sub.z)O.sub.(w+x+3z/2) Al.sub.2 O.sub.3 where A is barium, strontium or a combination thereof, B is magnesium which is replaceable partly or wholly by zinc and/or divalent manganese, w is in the range of from 0.01 to 0.6, x is in the range of from 0.01 to 0.98, y is in the range of from 0.005 w to 0.70 w, and z is in the range of from 0.0001 to 0.06, the divalent europium functioning as a sensitizer by absorbing ultraviolet radiation incident thereon and converting said radiation to energies that are absorbed by trivalent chromium and converted to infra-red radiation.
Claim 2
Dependent Claim
149 words
A trivalent chromium activated alkaline earth aluminate phosphor having a hexagonal crystal structure and divalent europium and optionally one or more of divalent manganese and zinc incorporated therein, and emitting in the region of the electromagnetic spectrum between 650 and 800 nm, having a composition represented by: (A.sub.(w-y) B.sub.x Eu.sub.y Cr.sub.z)O.sub.(w+x+3z/2) Al.sub.2 O.sub.3 where A is barium, strontium or a combination thereof, B is magnesium which is replaceable partly or wholly by zinc and/or divalent manganese, w is in the range of from 0.01 to 0.6, x is in the range of from 0.01 to 0.98, y is in the range of from 0.005 w to 0.70 w, and z is in the range of from 0.0001 to 0.06, the divalent europium functioning as a sensitizer by absorbing ultraviolet radiation incident thereon and converting said radiation to energies that are absorbed by trivalent chromium and converted to infra-red radiation.
Claim 3
Dependent Claim
11 words
A phosphor according to claim 1 having divalent manganese incorporated therein.
Claim 4
Dependent Claim
18 words
A phosphor according to claim 1 in which w is in the range of from 0.015 to 0.35.
Claim 5
Dependent Claim
18 words
A phosphor according to claim 3 in which w is in the range of from 0.075 to 0.30.
Claim 6
Dependent Claim
18 words
A phosphor according to claim 1 in which x is in the range of from 0.012 to 0.65.
Claim 7
Dependent Claim
18 words
A phosphor according to claim 5 in which x is in the range of from 0.055 to 0.45.
Claim 8
Dependent Claim
20 words
A phosphor according to claim 1 in which y is in the range of from 0.005 w to 0.50 w.
Claim 9
Dependent Claim
20 words
A phosphor according to claim 7 in which y is in the range of from 0.0075 w to 0.25 w.
Claim 10
Dependent Claim
18 words
A phosphor according to claim 1 in which z is in the range of from 0.0003 to 0.025.
Claim 11
Dependent Claim
18 words
A phosphor according to claim 9 in which z is in the range of from 0.0005 to 0.0125.
Claim 12
Dependent Claim
11 words
A luminescent screen comprising a phosphor as claimed in claim 1.
Claim 13
Dependent Claim
20 words
A fluorescent lamp comprising an envelope, the internal surface of which is coated with a phosphor according to claim 1.
Claim 14
Dependent Claim
16 words
A fluorescent lamp according to claim 12 which is a low pressure mercury vapour discharge lamp.
Claim 15
Dependent Claim
16 words
A fluorescent lamp according to claim 12 which is a low pressure cadmium vapour discharge lamp.
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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) | 1992-02-21 | 1992-08-22 | 1993-02-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-02-21 | 1996-08-22 | 1997-02-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-02-21 | 2000-08-22 | 2001-02-21 | $7700.00 | Window Closed / Lapsed |