US4387141A
Expired / Lapsed
US
⏱️ 0.0 years remaining
X-Ray screens based on phosphor mixtures of CaWO4 and rare earth tantalates
Assignee: Agfa Gevaert NV
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Filing: 1982-05-12
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Granted: 1983-06-07
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Expires: 2002-05-12
Abstract
Abstract X-ray intensifying screens with improved speed and image sharpness can be made from a phosphor mixture of calcium tungstate and yttrium tantalate. The tantalate phosphor may be further activated with rare earths.
Inventors
- 👤 Stanley H. Patten
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 18:02
CPC Classifications
G; G21; G21K; G21K4/00
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
126 words
An X-ray intensifying screen comprising a support, a phosphor mixture on said support, and a binder for said phosphor mixture, characterized in that said phosphor mixture consists essentially of calcium tungstate and a rare earth tantalate having the monoclinic M' structure and selected from the group consisting of: (a) YNb x TaO 1-x O 4 , where x is 0 to about 0.15; (b) LuNb x Ta 1-x O 4 , where x is 0 to about 0.20; (c) Y 1-y Tm y TaO 4 , where y is 0 to about 0.30; (d) a solid solution of (a) and (b); and, (e) a solid solution of (a) and (c) wherein the rare earth tantalate is present in an amount of 5% to 75% by weight.
Claim 2
Dependent Claim
126 words
An X-ray intensifying screen comprising a support, a phosphor mixture on said support, and a binder for said phosphor mixture, characterized in that said phosphor mixture consists essentially of calcium tungstate and a rare earth tantalate having the monoclinic M' structure and selected from the group consisting of: (a) YNb x TaO 1-x O 4 , where x is 0 to about 0.15; (b) LuNb x Ta 1-x O 4 , where x is 0 to about 0.20; (c) Y 1-y Tm y TaO 4 , where y is 0 to about 0.30; (d) a solid solution of (a) and (b); and, (e) a solid solution of (a) and (c) wherein the rare earth tantalate is present in an amount of 5% to 75% by weight.
Claim 3
Dependent Claim
24 words
The X-ray screen of claim 1 wherein the phosphor mixture is CaWO 4 /YTaO 4 :Nb in a 70/30 ratio in % by wt.
Claim 4
Dependent Claim
24 words
The X-ray screen of claim 1 wherein the phosphor mixture is CaWO 4 /YTaO 4 :Nb in a 90/10 ratio in % by wt.
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) | 1986-06-06 | 1986-12-06 | 1987-06-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-06-06 | 1990-12-06 | 1991-06-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-06-06 | 1994-12-06 | 1995-06-07 | $7700.00 | Window Closed / Lapsed |