Patent US4478933A successfully refreshed from Google Patents.
US4478933A
Expired / Lapsed
US
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Multi-layer X-ray screens
Assignee: General Electric Co
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Filing: 1983-10-11
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Granted: 1984-10-23
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Expires: 2003-10-11
Abstract
Abstract Rare earth oxyhalide phosphors activated with thulium ion are employed in X-ray intensifying screens having modified ultraviolet emission characteristics which reduce crossover effects without significant reduction in film speed and further increases screen brightness. Relatively low concentration levels of the thulium activator ion have been found to shift the ultraviolet emission of said phosphor when excited by X-rays to lower wavelengths in both the ultraviolet and near-ultraviolet spectral regions.
Inventors
- 👤 Jacob G. Rabatin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 18:43
CPC Classifications
C; C09; C09K; C09K11/00; C09K11/08; C09K11/77; C09K11/7766; C09K11/7767; C09K11/7769; C09K11/777; G; G21; G21K; G21K4/00; Y; Y10; Y10S; Y10S430/00; Y10S430/167; Y10S430/168
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
104 words
An improved X-ray screen comprising a double emulsion silver halide photographic film positioned between a pair of contiguous phosphor layers having a rare earth oxyhalide phosphor with the general formula: LnOX:Tm.sup.+3 wherein Ln is one or more of La and Gd, X is one or more of Cl and Br, Tm is present as sole activator at a concentration in the range from 0.0005 to 0.001 moles per mole of the selected oxyhalide, said phosphor exhibiting modified ultraviolet emission to reduce crossover effects without significant reduction in film speed and further providing more ultraviolet emission at 301 nanometers wavelength accompanied by increased screen brightness.
Claim 2
Dependent Claim
104 words
An improved X-ray screen comprising a double emulsion silver halide photographic film positioned between a pair of contiguous phosphor layers having a rare earth oxyhalide phosphor with the general formula: LnOX:Tm.sup.+3 wherein Ln is one or more of La and Gd, X is one or more of Cl and Br, Tm is present as sole activator at a concentration in the range from 0.0005 to 0.001 moles per mole of the selected oxyhalide, said phosphor exhibiting modified ultraviolet emission to reduce crossover effects without significant reduction in film speed and further providing more ultraviolet emission at 301 nanometers wavelength accompanied by increased screen brightness.
Claim 3
Dependent Claim
13 words
An X-ray screen as in claim 1 wherein said phosphor is lanthanum oxybromide.
Claim 4
Dependent Claim
21 words
An X-ray screen as in claim 1 wherein the film includes a base which transmits visible light but absorbs ultraviolet radiation.
Claim 5
Dependent Claim
13 words
An X-ray screen as in claim 1 which further includes light reflection means.
References Cited (Backward Citations)
US3795814A
Cited
US4070583A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-10-23 | 1988-04-23 | 1988-10-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-10-23 | 1992-04-23 | 1992-10-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-10-23 | 1996-04-23 | 1996-10-23 | $7700.00 | Window Closed / Lapsed |