US4431922A
Expired / Lapsed
US
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Mixed phosphors comprising both Gd2 O2 S and GdTaO4 and X-ray screens thereof
Assignee: Agfa Gevaert NV
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Filing: 1981-12-30
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Granted: 1984-02-14
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Expires: 2001-12-30
Abstract
Abstract An X-ray phosphor comprising a mixture of gadolinium oxysulfide and gadolinium tantalate, activated with trivalent terbium, is employed in X-ray conversion screens to convert X-rays to visible light, mostly in the green region of the spectrum.
Inventors
- 👤 Stanley H. Patten
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 15:12
CPC Classifications
G; G21; G21K; G21K4/00; C; C09; C09K; C09K11/00; C09K11/08; C09K11/77; C09K11/7766; C09K11/7767; C09K11/7769; C09K11/7771
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
64 words
An X-ray conversion screen consisting essentially of a mixed phosphor, a binder for said phosphor, and a substrate for said phosphor and said binder, said mixed phosphor consisting essentially of a major amount of gadolinium oxysulfide and a minor amount of gadolinium tantalate, and wherein from about 0.005 percent to 8 percent of the host metal ions have been replaced by trivalent terbium ions.
Claim 2
Dependent Claim
64 words
An X-ray conversion screen consisting essentially of a mixed phosphor, a binder for said phosphor, and a substrate for said phosphor and said binder, said mixed phosphor consisting essentially of a major amount of gadolinium oxysulfide and a minor amount of gadolinium tantalate, and wherein from about 0.005 percent to 8 percent of the host metal ions have been replaced by trivalent terbium ions.
Claim 3
Dependent Claim
18 words
The X-ray conversion screen of claim 1 wherein said mixed phosphor contains 5-20% by weight of gadolinium tantalate.
Claim 4
Dependent Claim
40 words
A mixed phosphor consisting essentially of a major amount of gadolinium oxysulfide and a minor amount of gadolinium tantalate, and wherein from about 0.005 percent to 8 percent of the host metal ions have been replaced by trivalent terbium ions.
Claim 5
Dependent Claim
40 words
A mixed phosphor consisting essentially of a major amount of gadolinium oxysulfide and a minor amount of gadolinium tantalate, and wherein from about 0.005 percent to 8 percent of the host metal ions have been replaced by trivalent terbium ions.
Claim 6
Dependent Claim
18 words
The mixed phosphor of claim 3 wherein the gadolinium tantalate makes up 5-20% by weight of the mixture.
Claim 7
Dependent Claim
20 words
A combination of the X-ray conversion screen of claim 1 or 2 with a green-sensitized silver halide emulsion photographic film.
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) | 1987-02-13 | 1987-08-15 | 1988-02-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-02-13 | 1991-08-15 | 1992-02-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-02-13 | 1995-08-15 | 1996-02-14 | $7700.00 | Window Closed / Lapsed |