According to one embodiment, a sliding bearing unit includes a stationary shaft including a first radial bearing surface, a rotor, and a lubricant. The rotor includes a first cylinder and a second cylinder. The second cylinder includes a second radial bearing surface and is restricted in operation so that it does not rotate relative to the first cylinder. The lubricant, together with the first radial bearing surface and the second radial bearing surface, forms a dynamic pressure radial sliding bearing.

The disclosure relates to an X-ray tube, comprising a cathode and an anode, the cathode and anode being accommodated in a housing which provides a vacuum environment.

A bearing structure for an X-ray tube is provided that includes a journal bearing shaft with a radially protruding thrust bearing encased within a sleeve. The structure of sleeve is formed with enlarged traps or voids in the sleeve that are disposed adjacent various rotating anti-wetting seals/seal surfaces formed between the sleeve and the shaft. The geometry of the traps is formed to retain liquid metal/lubricating fluid within the gap defined by the bearing assembly and to direct to liquid metal flowing outwardly from the gap defined between the sleeve and the shaft away from the rotating anti-wetting seals and back towards the gap. This geometry allows the centrifugal forces exerted on the liquid metal by the rotation of the bearing structure to move the outflowing liquid metal away from the rotating anti-wetting seals to significantly reduce contact of the liquid metal with the seals.

A bearing structure for an X-ray tube is provided that includes a journal bearing shaft with a radially protruding thrust bearing encased within a bearing sleeve, one of which rotates relative to the other. The stationary component, e.g., the journal bearing and/or the thrust bearing includes at least one vent groove formed therein that improves the ability of the journal bearing structure to enable gases trapped by the liquid metal within the bearing assembly to escape through the vent groove to the exterior of the X-ray tube. By adding a strategically located channel or vent groove of sufficient size in at least one of the journal bearing or the thrust bearing, the pressures resisted by the seal created between the liquid metal and the vent groove(s) in the bearing components is significantly reduced, allowing escape of the gases to avoid detrimental effects to the operation of the X-ray tube, while maintaining the load carrying capacity of the bearing assembly.

In one embodiment, a rotating anode type X-ray tube comprises a fixed shaft having a first surface, a rotor, a cathode emitting electrons, and an anode target. The rotor comprises a first cylinder having a second surface, a second cylinder, and a third cylinder. A first threaded portion on an inner surface of the first cylinder and a second threaded portion on an outer peripheral surface of the third cylinder are tightened. A screw member is screwed in a third threaded portion on an inner peripheral surface of a hole which penetrates the third cylinder, and a tip portion of the screw member presses the second cylinder against the second surface.

A bearing structure for an X-ray tube is provided that includes a journal bearing shaft with a radially protruding thrust bearing encased within a sleeve. The structure of sleeve is formed with enlarged traps or voids in the sleeve that are disposed adjacent various rotating anti-wetting seals/seal surfaces formed between the sleeve and the shaft. The geometry of the traps is formed to retain liquid metal/lubricating fluid within the gap defined by the bearing assembly and to direct to liquid metal flowing outwardly from the gap defined between the sleeve and the shaft away from the rotating anti-wetting seals and back towards the gap. This geometry allows the centrifugal forces exerted on the liquid metal by the rotation of the bearing structure to move the outflowing liquid metal away from the rotating anti-wetting seals to significantly reduce contact of the liquid metal with the seals.

According to one embodiment, an X-ray tube includes an elongated anode target, a cathode, and a vacuum envelope. The cathode includes an electron emission source and a converging electrode including a trench portion. The trench portion includes a closest inner circumferential wall, an upper inner circumferential wall, and a lower inner circumferential wall. The electron emission source projects towards a opening of the trench portion from a boundary between the closest inner circumferential wall and the upper inner circumferential wall.

A bearing structure for an X-ray tube is provided that includes a journal bearing shaft with a radially protruding thrust bearing encased within a bearing sleeve, one of which rotates relative to the other. The stationary component, e.g., the journal bearing and/or the thrust bearing includes at least one vent groove formed therein that improves the ability of the journal bearing structure to enable gases trapped by the liquid metal within the bearing assembly to escape through the vent groove to the exterior of the X-ray tube. By adding a strategically located channel or vent groove of sufficient size in at least one of the journal bearing or the thrust bearing, the pressures resisted by the seal created between the liquid metal and the vent groove(s) in the bearing components is significantly reduced, allowing escape of the gases to avoid detrimental effects to the operation of the X-ray tube, while maintaining the load carrying capacity of the bearing assembly.

According to one embodiment, in an X-ray tube, an electron convergence cup has a first surface located closer to the anode, and an electron convergence groove opening on the first surface and housing a filament. The first surface has a first edge located on the opening, and a second edge located on the opening and opposite to the first edge in a first direction. The first edge is closer to an outer peripheral part than the second edge is. When the distance between the first edge and the filament in the first direction is defined as a first distance and the distance between the second edge and the filament in the first direction is defined as a second distance, the first distance is shorter than the second distance.

Various methods and systems are provided for an x-ray imaging system. In one example, an x-ray tube of the imaging system includes a rotor with a core forming a continuous unit with at least one of a retention sleeve and a bearing assembly sleeve. The rotor further includes one or more magnets disposed in the core and maintained in place by the retention sleeve.