Planar filament with focused, central electron emission
AssigneeMoxtek, Inc.
InventorsKasey Otho GREENLAND, Todd S. PARKER
Life of this patent
Estimating the term…
Abstract
A planar filament for an x-ray tube can have a different cross-sectional area at different locations. In regions of smaller cross-sectional area, there can be higher current density, and thus increased heating and higher temperature of the wire. In regions of larger cross-sectional area, there can be lower current density, and thus decreased heating of the wire. Regions of larger cross-sectional area can also be stronger, thus reducing early filament failures. Wider regions can have increased area for electron emission. By adjusting the cross-sectional area and width of the wire at different locations, electron emission can be largely confined to a center of the filament, and filament life can increase.
Claims20
An x-ray tube comprising:
- a cathode and an anode electrically insulated from one another, the cathode including a filament configured to emit electrons towards the anode, and the anode configured to emit x-rays out of the x-ray tube in response to impinging electrons from the filament;
- the filament is an elongated wire extending non-linearly in a plane between a pair of electrodes, the filament capable of being heated by an electrical current through the elongated wire due to a voltage differential across the pair of electrodes;
- the filament includes a spiral segment with the elongated wire forming at least one complete revolution about an axis at a center of the filament, on either side of the axis, the filament forming a double spiral shape oriented parallel to the plane;
- the filament includes a thin-region and a pair of thick-regions, the thin-region is thinner than the pair of thick-regions;
- the thin-region is electrically-coupled between the pair of thick-regions with a smooth transition of thickness of the wire between each thick-region and the thin-region;
- T71/T72 ≥ 1.1, where T71 is a minimum thickness of the wire in the pair of thick-regions and T72 is a maximum thickness of the wire in the thin-region;
- W72/W71 ≥ 1.1, where W72 is a minimum width of the wire in the thin-region and W71 is a maximum width of the wire in the pair of thick-regions;
- a smooth transition of width of the wire between each thick-region and the thin-region;
- and
- a center of the filament is wider and thinner than any other part of the filament.
An x-ray tube comprising:
- a cathode and an anode electrically insulated from one another, the cathode including a filament configured to emit electrons towards the anode, and the anode configured to emit x-rays out of the x-ray tube in response to impinging electrons from the filament;
- the filament is an elongated wire extending non-linearly in a plane between a pair of electrodes, the filament capable of being heated by an electrical current through the elongated wire due to a voltage differential across the pair of electrodes;
- the filament includes a thin-region and a pair of thick-regions, the thin-region is thinner than the pair of thick-regions;
- the thin-region is electrically-coupled between the pair of thick-regions with a smooth transition of thickness of the wire between each thick-region and the thin-region;
- and
- T71/T72 ≥ 1.1, where T71 is a minimum thickness of the wire in the pair of thick-regions and T72 is a maximum thickness of the wire in the thin-region.
An x-ray tube comprising:
- a cathode and an anode electrically insulated from one another, the cathode including a filament configured to emit electrons towards the anode, and the anode configured to emit x-rays out of the x-ray tube in response to impinging electrons from the filament;
- the filament is an elongated wire extending non-linearly in a plane between a pair of electrodes, the filament capable of being heated by an electrical current through the elongated wire due to a voltage differential across the pair of electrodes;
- the filament includes a spiral segment with the elongated wire forming at least one complete revolution about an axis at a center of the filament, on either side of the axis;
- and
- the filament includes a thin-region and a pair of thick-regions, the thin-region is thinner than the pair of thick-regions, and the thin-region is electrically-coupled between the pair of thick-regions.
Dependencies are inferred from the claim text.