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US4007394A
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Alkali metal alkaline earth metal sulfate phosphor activated with cerium and terbium and lamp containing same
Assignee: General Electric Co
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Filing: 1975-04-07
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Granted: 1977-02-08
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Expires: 1995-04-07
Abstract
Abstract Mixed rare earth alkali and alkaline earth sulfates activated with cerium and terbium are used as a phosphor coating system for fluorescent lamps. The phosphor efficiently emits light in the green region and the emission spectrum of the phosphor demonstrates a prominent peak in the 520-560 nm region with minor inflections at other visible wavelengths.
Inventors
- 👤 Jacob G. Rabatin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 09:19
CPC Classifications
C; C09; C09K; C09K11/00; C09K11/08; C09K11/77; C09K11/7766; C09K11/7781
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
63 words
A luminescent material comprising crystals of: M.sub.w Ca.sub.x Ce.sub.y Tb.sub.z SO.sub.4 wherein M = Lithium or sodium w = y + z x = 1 - (w + Y + z) > 0.3 y = 0.05 to 0.25 z = 0.05 to 0.20 said material exhibiting relatively high quantum efficiencies for emissions in the visible green spectral region, when excited by 2537A radiation
Claim 2
Dependent Claim
63 words
A luminescent material comprising crystals of: M.sub.w Ca.sub.x Ce.sub.y Tb.sub.z SO.sub.4 wherein M = Lithium or sodium w = y + z x = 1 - (w + Y + z) > 0.3 y = 0.05 to 0.25 z = 0.05 to 0.20 said material exhibiting relatively high quantum efficiencies for emissions in the visible green spectral region, when excited by 2537A radiation
Claim 3
Dependent Claim
17 words
A luminescent material in accordance with claim 1 characterized by the formula: Li.sub..3 Ca.sub..4 Ce.sub..2 Tb.sub..1 SO.sub.4.
Claim 4
Dependent Claim
63 words
A fluorescent lamp including a sealed glass envelope having means contained therein to generate 254 nm radiation and coated on an inner surface of said envelope a phosphor material comprising crystals of: M.sub.w Ca.sub.x Ce.sub.y Tb.sub.z SO.sub.4 wherein M = lithium or sodium w = y + z x = 1 - (w+Y+z)>0.3 y = 0.05 to 0.25 z = 0.05 to 0.20
Claim 5
Dependent Claim
63 words
A fluorescent lamp including a sealed glass envelope having means contained therein to generate 254 nm radiation and coated on an inner surface of said envelope a phosphor material comprising crystals of: M.sub.w Ca.sub.x Ce.sub.y Tb.sub.z SO.sub.4 wherein M = lithium or sodium w = y + z x = 1 - (w+Y+z)>0.3 y = 0.05 to 0.25 z = 0.05 to 0.20
Claim 6
Dependent Claim
19 words
The lamp of claim 3 wherein the phosphor material is characterized by the formula: Li.sub..3 Ca.sub..4 Ce.sub..2 Tb.sub..1 SO.sub.4.
Claim 7
Independent Claim
112 words
a method of phosphor preparation comprising the steps: a. blending a mixture of phosphor ingredients consisting essentially of: a. one salt from the group Li 2 CO 3 , Na 2 CO 3 b. CaCO 3 c. Ce(NO 3 ) 3 .sup.. 6H 2 O d. Tb 4 O 7 e. (NH 4 ) 2 SO 4 in preselected amounts to form M.sub.w Ca.sub.x Ce.sub.y Tb.sub.z SO.sub.4 wherein M = lithium or sodium w = y+z x = 1 - (w+y+z)>0.3 y = 0.05 to 0.25 z = 0.05 to 0.20 b. and firing the blended mixture in a covered vessel at elevated temperatures in the range 300°-500° C for 1-2 hours.
Claim 8
Independent Claim
112 words
a method of phosphor preparation comprising the steps: a. blending a mixture of phosphor ingredients consisting essentially of: a. one salt from the group Li 2 CO 3 , Na 2 CO 3 b. CaCO 3 c. Ce(NO 3 ) 3 .sup.. 6H 2 O d. Tb 4 O 7 e. (NH 4 ) 2 SO 4 in preselected amounts to form M.sub.w Ca.sub.x Ce.sub.y Tb.sub.z SO.sub.4 wherein M = lithium or sodium w = y+z x = 1 - (w+y+z)>0.3 y = 0.05 to 0.25 z = 0.05 to 0.20 b. and firing the blended mixture in a covered vessel at elevated temperatures in the range 300°-500° C for 1-2 hours.
Claim 9
Dependent Claim
34 words
The method of claim 5 together with the steps of reblending the first fired material, then refiring the material in a covered vessel at elevated temperatures in the range 600°-750° C from 1-4 hours.
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) | 1980-02-08 | 1980-08-09 | 1981-02-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-02-08 | 1984-08-09 | 1985-02-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-02-08 | 1988-08-09 | 1989-02-08 | $7700.00 | Window Closed / Lapsed |