Dual filament, electrostatically controlled focal spot for x-ray tubes
US6480572B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 9, 2001 |
| Grant date | Nov 12, 2002 |
| Priority date | — |
| Expiry date | Mar 9, 2021 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J2235/068
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A dual filament x-ray tube assembly (16) includes an evacuated envelope (52) having an anode (54) disposed at a first end of the evacuated envelope (52) and a cathode assembly (62) disposed at a second end of the evacuated envelope (52). The cathode assembly includes a variable-length filament assembly (72, 74; 100) which emits electron beams for impingement on the anode (54) at focal spots having varying lengths. The cathode assembly (62) further includes a cathode cup (64, 66, 68; 110, 112) which is subdivided into a plurality of electrically insulated deflection electrodes (64, 66, 68; 110, 112). A filament select circuit (80) selectively and individually heats a portion of the variable-length filament assembly (72, 74). Electron beams emitted from the filament assembly (72, 74) are electrostatically focused and controlled by applying potentials to different ones of the deflection electrodes (64, 66, 68; 110, 112). The x-ray tube assembly (16) provides longer focal spots for thick-slice scanning applications and shorter focal spots for thin-slice scanning applications along with the benefit of electrostatic focusing and control.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.