US6071432A
Expired / Lapsed
US
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Long persistence red phosphors
Assignee: Sarnoff Corp
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Filing: 1998-06-16
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Granted: 2000-06-06
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Expires: 2018-06-16
Abstract
Abstract Red and orange-red emitting long persistence phosphors based on strontium sulfide and activated with a divalent rare earth such as europium, can be made by heating in the presence of an ammonium halide, or a trivalent rare earth. Using ammonium halide as the flux, the red-emitting phosphor can be molded into a desired shape. Using ammonium halide and powdered alumina, the red-emitting phosphor can be made into a powder directly. Heating a rare earth activated (Eu) strontium sulfide in the presence of a trivalent rare earth salt in the presence of sulfur and a source of carbon, fine particle size red-emitting phosphor particles can be made.
Inventors
- 👤 Perry Neil Yocom
- 👤 Diane Zaremba
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 13:57
CPC Classifications
C; C09; C09K; C09K11/00; C09K11/08; C09K11/77; C09K11/7728; C09K11/7729; C09K11/7731; C09K11/7783; C09K11/7784; C09K11/7786; H; H10; H10H; H10H20/00; H10H20/80; H10H20/85; H10H20/851; H10H20/8511; H10H20/8512
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
37 words
A method of making a powdered long persistence strontium sulfide based red emitting phosphor comprising heating a europium activated strontium sulfide in the presence of ammonium halide at a temperature of from about 900 to 1500° C.
Claim 2
Independent Claim
37 words
A method of making a powdered long persistence strontium sulfide based red emitting phosphor comprising heating a europium activated strontium sulfide in the presence of ammonium halide at a temperature of from about 900 to 1500° C.
Claim 3
Independent Claim
45 words
A method of making a solid, long persistence SrS based red emitting phosphor comprising heating a Eu activated strontium sulfide in the presence of NH 4 X at a temperature of from about 900 to 1500° C. wherein the phosphor is made in a mold.
Claim 4
Independent Claim
45 words
A method of making a solid, long persistence SrS based red emitting phosphor comprising heating a Eu activated strontium sulfide in the presence of NH 4 X at a temperature of from about 900 to 1500° C. wherein the phosphor is made in a mold.
Claim 5
Independent Claim
41 words
A method of making a powdered long persistence strontium sulfide based red emitting phosphor comprising mixing europium activated strontium sulfide with powdered alumina, and heating in the presence of an ammonium halide at a temperature of about 900 to 1500° C.
Claim 6
Independent Claim
41 words
A method of making a powdered long persistence strontium sulfide based red emitting phosphor comprising mixing europium activated strontium sulfide with powdered alumina, and heating in the presence of an ammonium halide at a temperature of about 900 to 1500° C.
Claim 7
Independent Claim
49 words
A method of making a long persistence strontium sulfide based red emitting phosphor comprising activating with divalent europium and a trivalent rare earth and firing at a temperature of about 1200° C. in the presence of vaporized sulfur passed over a carbon source to form a CS 2 atmosphere.
Claim 8
Independent Claim
49 words
A method of making a long persistence strontium sulfide based red emitting phosphor comprising activating with divalent europium and a trivalent rare earth and firing at a temperature of about 1200° C. in the presence of vaporized sulfur passed over a carbon source to form a CS 2 atmosphere.
Claim 9
Dependent Claim
28 words
A method according to claim 4 wherein the europium rare earth is present in an amount of from about 0.01 to 2 atomic percent of the strontium sulfide.
Claim 10
Dependent Claim
29 words
A method according to claim 4 wherein the trivalent rare earth is selected from the group consisting of praseodymium, neodymium, samarium, gadolinium, terbium, dysprosium, holmium, erbium, thulium and lutecium.
Claim 11
Dependent Claim
21 words
A method according to claim 6 wherein the trivalent rare earth is erbium and the firing temperature is about 1200° C.
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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) | 2003-06-06 | 2003-12-06 | 2004-06-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2007-06-06 | 2007-12-06 | 2008-06-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2011-06-06 | 2011-12-06 | 2012-06-06 | $7700.00 | Window Closed / Lapsed |