Patent EP0455401A2 successfully refreshed from Google Patents.
EP0455401A2
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Encapsulated electroluminescent phosphor and method for making same
Assignee: 3M Co
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Filing: 1991-04-23
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Granted: —
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Expires: 2011-04-23
Abstract
Abstract Encapsulated electroluminescent phosphor particles and method for making same. The phosphor particles are encapsulated in a very thin oxide layer to protect them from aging due to moisture intrusion. The particles are encapsulated via a vapor phase hydrolysis reaction of oxide precursor materials at a temperature of between about 25 DEG C and about 170 DEG C, preferably between about 100 DEG C and about 150 DEG C. The resultant encapsulated particles exhibit a surprising combination of high initial luminescent brightness and high resistance to humidity-accelerated brightness decay. <IMAGE>
Inventors
- 👤 D. Budd C/O Minnesota Mining And Kenton
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 17:34
CPC Classifications
C; C23; C23C; C23C16/00; C23C16/44; C23C16/442; C09; C09K; C09K11/00; C09K11/08; C09K11/70; C09K11/02; C09K11/025; C23C16/22; C23C16/30; C23C16/40; C23C16/405; Y; Y10; Y10S; Y10S428/00; Y10S428/917; Y10T; Y10T428/00; Y10T428/29; Y10T428/2982; Y10T428/2991; Y10T428/2993
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
104 words
Encapsulated electroluminescent phosphor particles, characterized in that each comprises a particle of electroluminescent phosphor which is essentially completely encapsulated within a substantially transparent, continuous oxide coating; wherein said encapsulated phosphor particles have an initial electroluminescent brightness which is equal to or greater than about 50 percent of the initial electroluminescent brightness of the uncoated phosphor particles, and wherein the percent of luminescent brightness retained following 100 hours operation in an environment having a relative humidity of at least 95 percent is greater than about 70 percent of the intrinsic brightness retained following 100 hours operation, the operation temperature, voltage, and frequency being substantially equal.
Claim 2
Dependent Claim
71 words
The encapsulated phosphor particles of claim 1 further characterized in at least one of the following: a) the initial electroluminescent brightness of said particles is equal to or greater than about 70 percent of the initial luminescent brightness of the uncoated phosphor particles; or b) the initial electroluminescent brightness of said particles is equal to or greater than about 80 percent of the initial luminescent brightness of the uncoated phosphor particles.
Claim 3
Dependent Claim
47 words
The encapsulated phosphor particles of claim 1 further characterized in at least one of the following: a) said retained electroluminescent brightness is greater than about 80 percent of said intrinsic brightness; or b) said retained electroluminescent brightness is greater than about 90 percent of said intrinsic brightness.
Claim 4
Dependent Claim
78 words
The encapsulated phosphor particles of claim 1 further characterized at least one of the following: a) said particles comprise zinc sulfide-based phosphor materials; or b) said particles comprise zinc sulfide-based phosphor materials and contain minor amounts of one or more of the following: cadmium, selenium, copper, bromine, chlorine, manganese, or silver; c) said particles are between about 1 and about 50 microns in diameter; or d) said particles are between about 10 and about 40 microns in diameter.
Claim 5
Dependent Claim
60 words
The encapsulated phosphor particles of claim 1 further characterized in at least one of the following: a) said coating is between about 0.1 and about 3.0 microns thick; or b) said coating is between about 0.1 and about 0.5 microns thick; or c) said coating comprises at least one of the following: titania, silica, alumina, tin oxide, zirconia, or mullite.
Claim 6
Dependent Claim
83 words
A process for encapsulating phosphor particles in substantially transparent oxide coatings said process characterized in that it comprises: a) providing an agitated bed of phosphor particles; b) heating said bed to a temperature of between about 25°C and about 170°C; c) exposing said bed to one or more vapor phase oxide precursors such that said precursors chemically react and form hermetic, substantially transparent oxide coatings on the surfaces of said particles, thereby yielding essentially encapsulated phosphor particles; and d) cooling said encapsulated particles.
Claim 7
Dependent Claim
23 words
The process of claim 6 further characterized in that said bed is heated to a temperature of between about 100°C and about 150°C.
Claim 8
Dependent Claim
47 words
The process of claim 6 further characterized in at lest one of the following: a) said vapor phase oxide precursors comprise water vapor, titanium tetrachloride, and silicon tetrachloride; or b) said vapor phase oxide precursors comprise water vapor and one or more metal alkoxides or metal chlorides.
Claim 9
Dependent Claim
51 words
The process of claim 6 further characterized in at least one of the following: a) said phosphor particles comprise zinc sulfide-based phosphor materials; or b) said particles comprise zinc sulfide-based phosphor materials and contain minor amounts of one or more of the following: cadmium, selenium, copper, bromine, chlorine, manganese, or silver.
Claim 10
Dependent Claim
71 words
The process of claim 6 further characterized in at least one of the following: a) said phosphor particles are between about 1 and about 50 microns in diameter; or b) said phosphor particles are between about 10 and about 40 microns in diameter; or c) said oxide coatings are between about 0.1 and about 3.0 microns thick; or d) said oxide coatings are between about 0.1 and about 0.5 microns thick.
References Cited (Backward Citations)
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