US3883760A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Field emission x-ray tube having a graphite fabric cathode
Assignee: Bendix Corp
•
Filing: 1971-04-07
•
Granted: 1975-05-13
•
Expires: 1991-04-07
Abstract
Abstract Several field emission diode x-ray tubes, each having a graphite fabric cathode mounted in a spaced, insulated relationship with respect to an anode are described herein. The different tubes illustrate various shaped cathodes. The tubes are pulse type xray generators. A burst of x-ray is generated by transmitting a high potential pulse of electrical energy, generally on the order of 100 to 300 kilovolts to the x-ray tube. This high potential causes electrons to be emitted from the cathode and strike the anode with sufficient energy to generate x-rays. The fabric cathode is woven from carbon graphite threads. Each of the threads forming the fabric is formed from a large number of thin carbon graphite filaments. The high electric potential supplied to the tube during operation causes the ends of the filaments to fray or spread so that each of the individual filaments acts as an electron emitter.
Inventors
- 👤 Jr Thomas C Cunningham
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 06:39
CPC Classifications
H; H01; H01J; H01J35/00; H01J35/02; H01J35/04; H01J35/06; H01J35/065; H01J35/22
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
260 words
In a field emission x-ray tube requiring a large electric potential in order to provide x-rays and having an evacuated envelope with an anode mounted within said envelope, the improvement comprising: a field emission cathode formed from a woven fabric, said fabric having a predetermined number of threads disposed in a first direction and having free ends for emitting electrons, a second predetermined number of threads disposed in a second direction, said second number of threads crossing and supporting said electron emitting threads; said fabric also having a sufficiently high resistivity to temperature to resist erosion by melting and sublimation during operation of the field emission x-ray tube, a sufficiently high tensile strength to resist being pulled apart by the large electric potential required by the field emission x-ray tube during operation, and a sufficiently low electric resistivity to provide a predetermined large number of electrons in response to said large electric potential; said electrons being accelerated by said large electric potential to strike said anode and provide a predetermined number of x-rays; said fabric cathode being mounted within said envelope in a spaced, insulated relationship with respect to said anode; said anode comprising a pointed rod; and said fabric cathode comprising a washer-shaped annulus defining a plane spaced from said anode, said spacing causing a large portion of the electrons emitted from said cathode during operation of the x-ray tube to strike the tip of said anode and thereby causing a large portion of the x-radiation emitted by said x-ray tube to be emitted from substantially the same position.
Claim 2
Dependent Claim
260 words
In a field emission x-ray tube requiring a large electric potential in order to provide x-rays and having an evacuated envelope with an anode mounted within said envelope, the improvement comprising: a field emission cathode formed from a woven fabric, said fabric having a predetermined number of threads disposed in a first direction and having free ends for emitting electrons, a second predetermined number of threads disposed in a second direction, said second number of threads crossing and supporting said electron emitting threads; said fabric also having a sufficiently high resistivity to temperature to resist erosion by melting and sublimation during operation of the field emission x-ray tube, a sufficiently high tensile strength to resist being pulled apart by the large electric potential required by the field emission x-ray tube during operation, and a sufficiently low electric resistivity to provide a predetermined large number of electrons in response to said large electric potential; said electrons being accelerated by said large electric potential to strike said anode and provide a predetermined number of x-rays; said fabric cathode being mounted within said envelope in a spaced, insulated relationship with respect to said anode; said anode comprising a pointed rod; and said fabric cathode comprising a washer-shaped annulus defining a plane spaced from said anode, said spacing causing a large portion of the electrons emitted from said cathode during operation of the x-ray tube to strike the tip of said anode and thereby causing a large portion of the x-radiation emitted by said x-ray tube to be emitted from substantially the same position.
References Cited (Backward Citations)
US2277712A
Cited
US3309523A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-05-12 | 1978-11-11 | 1979-05-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-12 | 1982-11-11 | 1983-05-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-12 | 1986-11-11 | 1987-05-13 | $7700.00 | Window Closed / Lapsed |