US3946261A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dual filament X-Ray tube
Assignee: Varian Medical Systems Inc
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Filing: 1975-01-03
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Granted: 1976-03-23
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Expires: 1995-01-03
Abstract
Abstract An X-ray tube including a tubular envelope having therein two cathode filaments operatively disposed in spaced relationship with an anode target surface, one filament being made of a material suitable for low current operation and the other filament being made of a material suitable for high current operation of the X-ray tube.
Inventors
- 👤 William P. Holland
- 👤 Capleton I. Swanson
- 👤 Jacob A. Randmer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 18:43
CPC Classifications
H; H01; H01J; H01J35/00; H01J35/02; H01J35/04; H01J35/06; H01J35/064; H01J35/066; H01J2235/00; H01J2235/06; H01J2235/068
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
68 words
An X-ray tube comprising: an envelope an anode having a target surface disposed within the envelope; and cathode means operatively spaced from the target surface and including a pair of separately operable, electron emitters for directing respective electron beams onto the target surface and generating associated X-ray beams, one of the emitters being made of thoriated tungsten material and the other being made of substantially pure tungsten material.
Claim 2
Dependent Claim
68 words
An X-ray tube comprising: an envelope an anode having a target surface disposed within the envelope; and cathode means operatively spaced from the target surface and including a pair of separately operable, electron emitters for directing respective electron beams onto the target surface and generating associated X-ray beams, one of the emitters being made of thoriated tungsten material and the other being made of substantially pure tungsten material.
Claim 3
Dependent Claim
32 words
An X-ray tube as set forth in claim 1 wherein the emitters comprise respective helically wound filaments, the thoriated tungsten filament having a larger electron emitting surface than the pure tungsten filament.
Claim 4
Dependent Claim
35 words
An X-ray tube as set forth in claim 1 wherein the cathode means includes electrical means for energizing the thoriated tungsten filament to emit a higher electron current than emitted by the pure tungsten filament.
Claim 5
Dependent Claim
43 words
An X-ray tube as set forth in claim 3 wherein the cathode means includes electron focusing means operatively associated with the respective filaments for focusing electrons emitted therefrom onto respective focal spot areas of the target surface to generate the associated X-ray beams.
Claim 6
Dependent Claim
56 words
An X-ray tube as set forth in claim 4 wherein the electron focusing means includes means for focusing electrons emitted from the thoriated tungsten filament onto a larger focal spot area than the electrons emitted from the pure tungsten filament to generate a higher flux X-ray beam than produced by electrons from the pure tungsten filament.
Claim 7
Dependent Claim
56 words
An X-ray tube as set forth in claim 4 wherein the electron focusing means includes means for focusing electrons emitted from the pure tungsten filament onto a smaller focal spot area than electrons emitted from the thoriated tungsten filament to generate a higher resolution X-ray beam than produced by the electrons from the thoriated tungsten filament.
Claim 8
Dependent Claim
28 words
An X-ray tube as set forth in claim 4 wherein the electron focusing means comprises a pair of spaced focusing cups, each having a respective filament disposed therein.
Claim 9
Dependent Claim
26 words
An X-ray tube as set forth in claim 7 wherein the electron focusing means includes terminal means for applying respective electrical potentials to the focusing cups.
References Cited (Backward Citations)
US1986466A
Cited
US2764706A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-03-23 | 1979-09-22 | 1980-03-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-03-23 | 1983-09-22 | 1984-03-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-03-23 | 1987-09-22 | 1988-03-23 | $7700.00 | Window Closed / Lapsed |