US4039830A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrostatic x-ray image recording device with mesh-base photocathode photoelectron discriminator means
Assignee: General Electric Co
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Filing: 1976-08-13
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Granted: 1977-08-02
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Expires: 1996-08-13
Abstract
Abstract An electrostatic X-ray image recording device having a pair of spaced electrodes with a gas-filled gap therebetween, and including discrimination means, having a conductive mesh supporting a photocathodic material, positioned in the gas-filled gap between a first electrode having a layer of ultraviolet-emitting fluorescent material and a second electrode having a plastic sheet adjacent thereto for receiving photoelectrons emitted by the photocathodic material and accelerated to the second electrode by an applied field. The photoconductor-mesh element discriminates against fast electrons, produced by direct impingement of X-rays upon the photocathode to substantially reduce secondary electron production and amplification, thereby increasing both the signal-to-noise and contrast ratios. The electrostatic image formed on the plastic sheet is developed by zerographic techniques after exposure.
Inventors
- 👤 Kei-Hsiung Yang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 07:47
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/054; G03G15/0545
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
175 words
A device for the electrostatic recording of images produced responsive to differential absorption of X-rays by an object, comprising: a first electrode emitting light photons responsive to quanta of X-rays impinging thereupon; a second electrode spaced from said first electrode to form a gap therebetween, said second electrode including a layer of an insulating material on a surface thereof facing said first electride; a gas filling gap between said first and second electrodes; means for generating an electric field in the gap between said first and second electrodes; and means positioned in said gap and spaced from said first and second electrodes for emitting primary slow and fast electrons respectively responsive to impingement thereon of said light photons and at least a portion of said X-rays and for discriminating between said fast and slow electrons to allow said slow electrons to be accelerated across said gap by said electric field for deposition upon said insulating layer and to substantially prevent said fast electrons from entering the gap between said discriminator means and said second electrode.
Claim 2
Independent Claim
175 words
A device for the electrostatic recording of images produced responsive to differential absorption of X-rays by an object, comprising: a first electrode emitting light photons responsive to quanta of X-rays impinging thereupon; a second electrode spaced from said first electrode to form a gap therebetween, said second electrode including a layer of an insulating material on a surface thereof facing said first electride; a gas filling gap between said first and second electrodes; means for generating an electric field in the gap between said first and second electrodes; and means positioned in said gap and spaced from said first and second electrodes for emitting primary slow and fast electrons respectively responsive to impingement thereon of said light photons and at least a portion of said X-rays and for discriminating between said fast and slow electrons to allow said slow electrons to be accelerated across said gap by said electric field for deposition upon said insulating layer and to substantially prevent said fast electrons from entering the gap between said discriminator means and said second electrode.
Claim 3
Dependent Claim
71 words
A device as set forth in claim 1, wherein said discriminator means comprises a conductive mesh screen having a plurality of apertures formed therethrough, said conductive screen being maintained at a more negative electrical potential than said second electrode; and a photocathodic material deposited only upon the mesh portions of said screen member and facing said first electrode, said photocathodic material emitting photoelectrons responsive to impingement thereon of said light photons.
Claim 4
Dependent Claim
26 words
A device as set forth in claim 2, wherein said photocathodic material comprises a material selected from the group consisting of cesium iodide and cadmium telluride.
Claim 5
Dependent Claim
29 words
A device as set forth in claim 2, wherein the ratio of the diameter of said apertures to the thickness of said screen member is less than about 2:1.
Claim 6
Dependent Claim
18 words
A device as set forth in claim 2, wherein said apertures have a diameter of about 25 microns.
Claim 7
Dependent Claim
19 words
A device as set forth in claim 5, wherein said apertures have a center-to-center spacing of about 40 microns.
Claim 8
Dependent Claim
28 words
A device as set forth in claim 2, wherein the separation distance between facing surfaces of said first electrode and said first discriminator means is about 5 microns.
Claim 9
Dependent Claim
39 words
A device as set forth in claim 1, wherein said discriminator means is maintained essentially at ground electrical potential and said first means maintains said second electrode at a positive potential with respect to at least said discriminator means.
Claim 10
Dependent Claim
26 words
A device as set forth in claim 8, wherein said first means maintains said second electrode at a positive potential with respect to said first electrode.
Claim 11
Dependent Claim
25 words
A device as set forth in claim 9, further comprising second means for applying another electric field between said discriminator means and said first electrode.
Claim 12
Dependent Claim
38 words
A device as set forth in claim 1, wherein said first electrode comprises a conductive layer upon which said X-rays impinge; and a layer of a phosphor material emitting said light photons responsive to receipt of said X-rays.
Claim 13
Dependent Claim
15 words
A device as set forth in claim 11, wherein said phosphor material emits ultraviolet photons.
References Cited (Backward Citations)
US3932750A
Cited
US3940620A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-08-01 | 1981-01-31 | 1981-08-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-08-01 | 1985-01-31 | 1985-08-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-08-01 | 1989-01-31 | 1989-08-02 | $7700.00 | Window Closed / Lapsed |