US5008591A
Expired / Lapsed
US
⏱️ 0.0 years remaining
X-ray image intensifier tube comprising a selective filter
Assignee: US Philips Corp
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Filing: 1990-01-08
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Granted: 1991-04-16
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Expires: 2010-01-08
Abstract
Abstract The entrance screen in an X-ray image intensifier includes an intermediate layer of a material which selectively absorbs photon energy. As a result, the speed of the photo-electrons is substantially reduced, thus improving the imaging. By introducing a radial variation of the absorption in the intermediate layer, vignetting-compensation can also be realized without substantial loss of sensitivity and resolution for the central portion of the tube. The resolution at the periphery of the tube can thus be substantially improved.
Inventors
- 👤 Johnny van der Velden
- 👤 Theodorus F. van Bergen
- 👤 August L. H. Simons
- 👤 Johannes K. E. Colditz
- 👤 Martinus A. C. Ligtenberg
- 👤 Franciscus M. Dreesen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 17:43
CPC Classifications
H; H01; H01J; H01J29/00; H01J29/02; H01J29/10; H01J29/36; H01J29/38; H01J29/385
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
65 words
An X-ray image intesifier tube, comprising an entrance screen, an exit screen and electron-optical means for projecting photo-electrons from the entrance screen onto the exit screen, the entrance screen successively comprising a luminescent layer, an intermediate layer and a photocathode, characterized in that the intermediate layer exhibits a selective absorption for photon energy, so that comparitively high-energetic photons are absorbed more than comparatively low-energetic photons.
Claim 2
Dependent Claim
65 words
An X-ray image intesifier tube, comprising an entrance screen, an exit screen and electron-optical means for projecting photo-electrons from the entrance screen onto the exit screen, the entrance screen successively comprising a luminescent layer, an intermediate layer and a photocathode, characterized in that the intermediate layer exhibits a selective absorption for photon energy, so that comparitively high-energetic photons are absorbed more than comparatively low-energetic photons.
Claim 3
Dependent Claim
38 words
An X-ray image intensifier tube as claimed in claim 1, characterized in that the luminescent layer contains CSi, the intermediate layer containing a semiconductor material with an energy gap of at least from approximately 2.0 to 3.0 eV.
Claim 4
Dependent Claim
34 words
An X-ray image intesifier tube as claim in claim 1, characterized in that the luminescent layer contains CsI (Na), the intermediate layer containing a semiconductor material with an energy gap of approximately 2.6 eV.
Claim 5
Dependent Claim
22 words
An X-ray image intensifier tube as claimed in claim 1, characterized in that the intermediate layer consists mainly of CdO or CdS.
Claim 6
Dependent Claim
21 words
An X-ray image intesifier tube as claimed in claim 1, characterized in that the intermediate layer exhibits a radial thickness variation.
Claim 7
Dependent Claim
25 words
An X-ray image intensifier tube as claimed in claim 1, characterized in that the intermediate layer exhibits a radial variation of the integral energy gap.
Claim 8
Dependent Claim
20 words
An X-ray image intensifier tube as claimed in claim 5, characterized in that the luminescent layer has a uniform thickness.
Claim 9
Dependent Claim
38 words
An X-ray image intensifier tube as claimed in claim 5, characterized in that the luminescent layer has a decreasing thickness in the direction of the periphery, which decrease is adapted to an X-ray beam geometry to be used.
Claim 10
Dependent Claim
32 words
An X-ray image intensifier tube as claimed in claim 1, characterized in that the intermediate layer exhibits a comparitively high absorption for the luminescent light in order to reduce photon reflecting therein.
Claim 11
Dependent Claim
20 words
An X-ray image intensifier tube as claimed in claim 9, characterized in that the intermediate layer contains a yellowing halogenide.
Claim 12
Dependent Claim
32 words
An X-ray image intensifier tube as claimed in claim 1, characterized in that the intermediate layer is formed by an outer layer of CsI doped for increased absorption of the luminescent light.
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) | 1994-04-15 | 1994-10-15 | 1995-04-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-04-15 | 1998-10-15 | 1999-04-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-04-15 | 2002-10-15 | 2003-04-16 | $7700.00 | Window Closed / Lapsed |