US3743836A
Expired / Lapsed
US
⏱️ 0.0 years remaining
X-ray focal spot control system
Assignee: Varian Medical Systems Inc
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Filing: 1972-02-22
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Granted: 1973-07-03
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Expires: 1992-02-22
Abstract
Abstract An X-ray generating system comprising an X-ray tube having an electron-emitting cathode disposed in spaced opposing relationship with an anode target surface and supported within a focusing cup which is provided with means for directing emitted electrons into a Gaussian distribution pattern on the target surface, such that the area of the resulting focal spot is minimized and useful X-rays radiate therefrom in a corresponding Gaussian distribution pattern.
Inventors
- 👤 W Holland
- 👤 G Bavor
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 19:57
CPC Classifications
H; H05; H05G; H05G1/00; H05G1/08; H05G1/26; H05G1/30; H05G1/52; H01; H01J; H01J35/00; H01J35/02; H01J35/04; H01J35/06; H01J35/066
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
160 words
An X-ray generating system for producing an X-ray focal spot having a minimized area and a Gaussian distribution of Xradiation, said system comprising: an X-ray tube including: an envelope, a focusing electrode supported within the envelope and having a recess therein, an electron-emitting cathode supported insulatingly within the recess, an anode having a target surface supported within the envelope opposite said recess; first means for impressing on the anode a positive voltage with respect to the cathode; second means for heating the cathode to an electron-emitting temperature; and biasing means for maintaining the focusing electrode at a negative potential with respect to the cathode during active operation of the tube and directing emitted electrons into a Gaussian distribution pattern on a minimized area of the target surface; said biasing means including a pulsating voltage source and an electrical circuit connecting the source to the tube, the circuit having control means and means for converting pulsating voltage to a steady-state voltage.
Claim 2
Dependent Claim
160 words
An X-ray generating system for producing an X-ray focal spot having a minimized area and a Gaussian distribution of Xradiation, said system comprising: an X-ray tube including: an envelope, a focusing electrode supported within the envelope and having a recess therein, an electron-emitting cathode supported insulatingly within the recess, an anode having a target surface supported within the envelope opposite said recess; first means for impressing on the anode a positive voltage with respect to the cathode; second means for heating the cathode to an electron-emitting temperature; and biasing means for maintaining the focusing electrode at a negative potential with respect to the cathode during active operation of the tube and directing emitted electrons into a Gaussian distribution pattern on a minimized area of the target surface; said biasing means including a pulsating voltage source and an electrical circuit connecting the source to the tube, the circuit having control means and means for converting pulsating voltage to a steady-state voltage.
Claim 3
Dependent Claim
44 words
An X-ray generating system as set forth in claim 1 wherein the voltage converting means includes a voltage filtering network having polarized output terminals, the negative output terminal being connected to the focusing electrode and the other output terminal being connected to the filament.
Claim 4
Dependent Claim
47 words
An X-ray generating system as set forth in claim 2 wherein the voltage converting means includes a rectifying means having input terminals connected through the control means to the output of the pulsating voltage source and output terminals connected to the input of the voltage filtering network.
Claim 5
Dependent Claim
41 words
An X-ray generating system as set forth in claim 1 wherein the control means includes switching means for applying a negative potential to the focusing electrode when desired and adjustable means for varying the magnitude of the negative potential when desired.
Claim 6
Dependent Claim
35 words
An X-ray generating system as set forth in claim 4 wherein the control means includes means for increasing the electron emitting temperature of the cathode when the negative potential is applied to the focusing electrode.
Claim 7
Dependent Claim
38 words
An X-ray generating system as set forth in claim 5 wherein the second means includes means for adjusting the electron-emitting temperature of the cathode in accordance with the magnitude of the negative potential applied to the focusing electrode.
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) | 1976-07-02 | 1977-01-01 | 1977-07-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-02 | 1981-01-01 | 1981-07-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-02 | 1985-01-01 | 1985-07-03 | $7700.00 | Window Closed / Lapsed |