US3791844A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Phosphors for multi-color displays
Assignee: RADIUM CORP
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Filing: 1972-05-02
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Granted: 1974-02-12
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Expires: 1992-05-02
Abstract
Abstract A phosphor composite consists of particles each having a core of gadolinium, yttrium or lutetium oxide activated with praseodymium, substantially completely surrounded by a shell of the corresponding oxysulfide or oxyfluoride. This phosphor when deposited on the face of a cathode ray tube emits light of distinctly different colors when excited by electron beams projected at substantially different voltages. A method for making the new phosphors is also described.
Inventors
- 👤 M Tecotzky
- 👤 J Mattis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 07:21
CPC Classifications
H; H01; H01J; H01J29/00; H01J29/02; H01J29/10; H01J29/18; H01J29/26; C; C09; C09K; C09K11/00; C09K11/08; C09K11/77; C09K11/7766; C09K11/7767; Y; Y10; Y10T; Y10T428/00; Y10T428/29; Y10T428/2982; Y10T428/2991
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
23 words
A phosphor particle according to claim 1 wherein the first composition is the oxide phosphor and the second composition is the oxy-compound phosphor.
Claim 2
Dependent Claim
23 words
A phosphor particle according to claim 1 wherein the first composition is the oxy-compound phosphor and the second composition is the oxide phosphor.
Claim 3
Dependent Claim
87 words
A phosphor particle having an inner core of substantially uniform first composition completely surrounded by a continuous shell of substantially uniform second composition, said first composition being a praseodymium activated oxide phosphor of a rare earth base selected from the group consisting of at least one of the elements gadolinium, yttrium and lutetium, and said second composition being a praseodymium activated oxysulfide phosphor of the same rare earth base as selected for the first composition, both said core and said surface layer displaying spectral emission upon excitation.
Claim 4
Dependent Claim
29 words
A phosphor particle according to claim 4 wherein the first composition is a praseodymium activated gadolinium oxide phosphor and the second composition is a praseodymium activated gadolinium oxysulfide phosphor.
Claim 5
Dependent Claim
29 words
A phosphor particle according to claim 4 wherein the frist composition is a praseodymium activated yttrium oxide phosphor and the second composition is a praseodymium activated yttrium oxysulfide phosphor.
Claim 6
Dependent Claim
28 words
A phosphor particle according to claim 4 wherein the first composition is praseodymium activated lutetium oxide phosphor and the second composition is a praseodymium activated lutetium oxysulfide phosphor.
Claim 7
Dependent Claim
76 words
A phosphor particle according to claim 1 wherein the oxide phosphor is substantially R(2 y)PryO3 and the oxy-compound phosphor is substantially R(w y)PryOwX where R is at least one rare earth element selected from the group consisting of gadolinium, yttrium and lutetium, X is an element selected from the group consisting of sulfur and fluorine, w is 1 when X is fluorine and is 2 when X is sulfur, and y is from 0.00001 to 0.05.
Claim 8
Dependent Claim
64 words
A phosphor particle according to claim 1 wherein the first composition is a rare earth oxide conforming substantially to the formula R(2 y)PryO3 and the second composition is a rare earth oxysulfide conforming substantially to the formula R(2 y)PryO2S where R is at least one rare earth element of the group consisting of gadolinium, yttrium and lutetium and y is from 0.00001 to 0.05.
Claim 9
Dependent Claim
64 words
A phosphor particle according to claim 1 wherein the first composition is a rare earth oxide conforming substantially to the formula R(2 y)PryO3 and the second composition is a rare earth oxyfluoride conforming substantially to the composition R(1 y)PryOF where R is at least one rare earth element of the group consisting of gadolinium, yttrium and lutetium, and y is from 0.00001 to 0.05.
Claim 10
Independent Claim
130 words
The method of making a phosphor which comprises heating at a temperature in the range from 1,200*F. to 2,000*F. particles of a praseodymium activated oxide phosphor of at least one rare earth base selected from the group consisting of gadolinium, yttrium and lutetium together with a reactant selected from the group consisting of sulfidizing agents and fluoridizing agents, the amount of said reactant in the mixture being substantially less than the stoichiometric amount required to convert the whole of said oxide phosphor to the corresponding oxy-reactant compound, and cooling the reaction product to room temperature, thereby forming particles having an oxide core of substantially uniform composition surrounded by a continuous surface layer of the praseodymium activated oxy-reactant compound phosphor of the same rare earth base as selected for the core.
Claim 11
Dependent Claim
28 words
The method according to claim 11, wherein the reactant is a sulfidizing agent and the recovered composite particles have a substantially continuous shell of substantially uniform oxysulfide composition.
Claim 12
Dependent Claim
30 words
The method according to claim 12 wherein the sulfidizing agent is at least one compound selected from the group consisting of sulfur dioxide plus hydrogen, hydrogen sulfide, and elemental sulfur.
Claim 13
Dependent Claim
28 words
The method according to claim 11 wherein the reactant is a fluoridizing agent and the recovered composite particles have a substantially continuous shell of substantially uniform oxyfluoride composition.
Claim 14
Dependent Claim
29 words
The method according to claim 14 wherein the reactant is at least one compound selected from the group consisting of ammonium fluoride, rare earth fluorides, hydrogen fluoride and fluorine.
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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) | 1977-02-11 | 1977-08-13 | 1978-02-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-11 | 1981-08-13 | 1982-02-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-11 | 1985-08-13 | 1986-02-12 | $7700.00 | Window Closed / Lapsed |