US4054798A
Expired / Lapsed
US
⏱️ 0.0 years remaining
X-ray conversion screens
Assignee: Toshiba Corp
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Filing: 1976-11-11
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Granted: 1977-10-18
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Expires: 1996-11-11
Abstract
Abstract An X-ray conversion screen having reduced afterglow without any appreciable loss in the brightness under X-ray excitation comprises a substrate and at least one fluorescent layer applied thereto, the fluorescent layer containing a fluorescent substance which comprises terbium-activated lanthanum or gadolinium oxyhalide having yttrium or lutetium and, as desired, ytterbium added thereto as impurities.
Inventors
- 👤 Minoru Watanabe
- 👤 Ryoichi Kubo
- 👤 Toshio Nishimura
- 👤 Kazuto Yokota
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 00:58
CPC Classifications
C; C09; C09K; C09K11/00; C09K11/08; C09K11/77; C09K11/7766; C09K11/7767; C09K11/7769; C09K11/777; G; G21; G21K; G21K4/00
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
119 words
An X-ray conversion screen comprising a substrate and at least one fluorescent layer applied thereto, said fluorescent layer containing at least one fluorescent substance which comprises a rare earth oxyhalide having the general formula: M.sub.1-v-w-z OX: Tb.sub.v Yb.sub.w L.sub.z wherein M is an element selected from the group consisting of lanthanum and gadolinium; X is an element selected from the group consisting of chlorine and bromine; L is an element selected from the group consisting of yttrium and lutetium; v is from 0.00005 to 0.05 mole per mole of the selected oxyhalide; w is not more than 0.005 mole per mole of the selected oxyhalide; and z is from 0.000001 to 0.05 mole per mole of the selected oxyhalide.
Claim 2
Dependent Claim
119 words
An X-ray conversion screen comprising a substrate and at least one fluorescent layer applied thereto, said fluorescent layer containing at least one fluorescent substance which comprises a rare earth oxyhalide having the general formula: M.sub.1-v-w-z OX: Tb.sub.v Yb.sub.w L.sub.z wherein M is an element selected from the group consisting of lanthanum and gadolinium; X is an element selected from the group consisting of chlorine and bromine; L is an element selected from the group consisting of yttrium and lutetium; v is from 0.00005 to 0.05 mole per mole of the selected oxyhalide; w is not more than 0.005 mole per mole of the selected oxyhalide; and z is from 0.000001 to 0.05 mole per mole of the selected oxyhalide.
Claim 3
Dependent Claim
22 words
An X-ray conversion screen according to claim 1 wherein v is from 0.0005 to 0.01 mole per mole of the selected oxyhalide.
Claim 4
Dependent Claim
22 words
An X-ray conversion screen according to claim 1 wherein w is not more than 0.001 mole per mole of the selected oxyhalide.
Claim 5
Dependent Claim
22 words
An X-ray conversion screen according to claim 1 wherein z is from 0.001 to 0.01 mole per mole of the selected oxyhalide.
Claim 6
Dependent Claim
17 words
An X-ray conversion screen according to claim 1 wherein said rare earth oxyhalide does not contain ytterbium.
Claim 7
Dependent Claim
37 words
An X-ray conversion screen according to claim 1 having at least two fluorescent layers which are arranged in such a manner that the fluorescent layer nearer to said substrate contains a fluorescent substance of larger grain size.
Claim 8
Dependent Claim
46 words
An X-ray conversion screen according to claim 1 wherein said fluorescent substance consists of a mixture of said rare earth oxyhalide and at least one member selected from the group consisting of CaWO 4 , BaSO 4 :Eu, and Ba 3 (PO 4 ) 2 :Eu.
Claim 9
Dependent Claim
49 words
An X-ray conversion screen according to claim 1 wherein said fluorescent substance consists of a mixture of said rare earth oxyhalide and at least one member selected from the group consisting of Y 2 O 2 S:Tb, La 2 O 2 S:Tb, Gd 2 O 2 S:Tb, and BaFCl:Eu.
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) | 1980-10-17 | 1981-04-18 | 1981-10-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-10-17 | 1985-04-18 | 1985-10-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-10-17 | 1989-04-18 | 1989-10-18 | $7700.00 | Window Closed / Lapsed |