Abstract: A high energy x-ray tube includes an evacuated chamber (12) containing a rotor (34) which rotates an anode (10) in the path of a stream of electrons (A) to generate an x-ray beam (B) and heat. The rotor includes an armature (36) which rotates around a stationary rotor support (40). An emissive coating is formed on the rotor by depositing an iron Fe.sub.3 O.sub.4 oxide plasma onto the surface of the armature. Heat generated in the anode during the production of x-rays is conducted through the anode and the rotor to the emissive coating which irradiates the heat across vacuum, thereby increasing the lifetime of the tube. A stator (32) generates an oscillating magnetic field which induces opposing fields in the Fe.sub.3 O.sub.4 coating to create the rotational forces to rotate the anode.

Abstract: The invention relates to a drive device for a rotary anode of an X-ray tube, including an induction motor (13) whereto an alternating voltage can be applied by means of an inverter (20), and also including a control unit (22) for controlling the inverter (20), the switching frequency of the inverter (20) being variable in time, in conformity with a frequency time characteristic, by means of the control unit (22). It is the object of the invention to provide a drive device for a rotary anode of an X-ray tube as well as a suitable control method which ensures the temperature-independent starting up of the rotary anode.

Abstract: A speed control apparatus for determining and controlling the speed of rotation of a rotor in an AC motor. The motor includes a stator having main and auxiliary windings. Main and auxiliary winding controllers control the operational input signals supplied to the main and auxiliary windings by a signal generator. A pulse generator is connected to the main winding for providing a test pulse during a speed measurement operation. The test pulse magnetizes a portion of the rotor which induces a feedback EMF signal in the auxiliary winding. A feedback sensor circuit receives the feedback signal and forwards it to a microprocessor. The microprocessor calculates the rotational speed of the rotor based on the feedback signal.

Abstract: A method for assembling a rotating X-ray tube structure ensures balance retention during the life of the tube. The X-ray tube structure has a cathode for emitting electrons, and a rotor and a bearing assembly for facilitating rotation of an anode. At least one joint is identified in the X-ray tube structure and interference fit assembly is used to eliminate shifts at the joint. The interference fit assembly is particularly advantageous for eliminating even the minutest shifts in the main joints of the anode assembly. Interference fit assembly can be applied between the rotor and the anode target to provide a first joint having balance retention; and interference fit assembly can be applied between the bearing assembly and the rotor to provide a second joint having balance retention.

Abstract: The invention relates to a drive device for a rotary anode of an X-ray tube having a drive motor with a stator (10) and a rotor (15; 21) which drives the rotary anode, the stator (10) and the rotor (15; 21) being separated by a gap and the stator (10) having slots (11) whose circumferential length (17) has been dimensioned for driving a bipolar X-ray tube. In order to enable a more universal use of such a drive device the stator (10), which has been dimensioned for driving the bipolar X-ray tube, is also used for driving a unipolar X-ray tube, the diameter of the rotor (21) and thus the gap (22) being dimensioned in such a manner that the efficiency or the torque of the drive device lies within a maximum range (II).

Abstract: The invention relates to an X-ray apparatus, comprising a rotary-anode X-ray tube, a device for monitoring the rotational speed of a rotary-anode drive motor of the X-ray tube, a sensor circuit for determining an angle signal which is dependent on the phase angle between a reference voltage and a current associated with the motor, a comparator circuit for detecting the angle signal variation which serves as a criterion for the rotational speed of the motor, and also comprising a frequency changer. Thanks to the fact that there is provided a device for forming a brief keying signal so as to trigger a reduction of the frequency of the rotary-anode drive motor, the device is also suitable for induction motors in which only a small phase angle variation is measured between standstill and the operating rotational speed.

Abstract: A linear accelerator x-ray target assembly including an electron beam which contacts an x-ray target and generates x-rays. The target is mounted such that it can rotate freely about its axis. The target has a contoured axially outer edge. Fluid flow impinging the contoured axially outer edge of the target acts to impart rotary motion on the target. The fluid flow helps to dissipate heat from the target in two ways. Firstly, heat is transferred to a cooling fluid as the cooling fluid passes over the target. Secondly, the rotation of the target helps to dissipate heat from the target by distributing the electron beam contact point around the target instead of having the electron beam impact continuously on one spot on the target.

Abstract: A method and apparatus for cooling a rotating anode X-ray tube. An electromagnetic motor is provided to rotate an X-ray anode with cooling passages in the anode. These cooling passages are coupled to a cooling structure located adjacent the electromagnetic motor. A liquid metal fills the passages of the cooling structure and electrical power is provided to the motor to rotate the anode and generate a rotating magnetic field which moves the liquid metal through the cooling passages and cooling structure.

Abstract: In an X-ray tomographic apparatus, while rotating a gantry rotary section around a region where an object to be photographed is placed, the anode target of an X-ray tube is rotated at a predetermined high rotation rate and X-rays are emitted from the anode target. In emitting the X-rays, the rotation torque is increased to be larger than that prior to rotation of the gantry rotary section in accordance with the rotation drive power supplied to a stator coil. A decrease in rotation rate of the anode target of the X-ray tube can be prevented even during rotation of the gantry rotary section, radiation at a necessary and sufficient X-ray dose can be assured, and an X-ray tomographic image can be properly obtained.

Abstract: A method of balancing X-ray anodes wherein the anode rotor is dynamically balanced separately from the anode target, the anode target is then attached to the anode rotor to provide the assembled anode, and the assembled anode is then dynamically balanced. This sequential balancing method has the advantage that it results in an anode which remains balanced during operation at speeds up to and exceeding the anode's critical speeds, even though the dynamic balancing steps may be performed at speeds substantially below the anode's critical speeds. This is also convenient because at such low balancing speeds, the dynamic balancing steps can be performed in air rather than vacuum without concern for oxidation and spalling of the rotor bearings, excessive vibration, and potential safety concerns.

Abstract: A cooling system for an X-ray system with a bearing assembly having a bearing stator and a bearing rotor, includes a cooling stem disposed within the bearing assembly for dissipation of heat from the X-ray system. The cooling stem has dimensions adapted to be disposed within an axial bore of the bearing assembly. The cooling stem consists of a hollow, tubular housing having a target end, a distal end, and a number of radial fins integral with the outer surface of the tubular housing. The radial fins extend longitudinally from the target end in the direction of the distal end to a transition point. The radial fins, in combination with the outer surface of the tubular housing and the inner surface of the axial bore, form a number of axial channels for channeling a cooling medium from the target end to the distal end in a turbulent flow.

Abstract: An X-ray generating source comprising a rotating vacuum envelope with an anode attached thereto and a cathode assembly disposed therewith. The cathode assembly is held stationary within the vacuum envelope exclusively by a magnetic suspension system which comprises a magnet assembly formed by a plurality of electromagnets mounted on two spaced apart rings positioned outside of the envelope and located in the place which is perpendicular to an axis of rotation of the envelope and a magnetic susceptor mounted to the cathode assembly. A plurality of proximity sensors are sensing any displacements of the cathode assembly while a feedback control system being connected to these proximity sensors maintains the proper position of the cathode assembly by changing the value of the magnetic field in gaps between the magnet assembly and the magnetic susceptor.

Abstract: An improved high performance x-ray system having a rotating anode therein which includes an improved target/stem assembly comprising a metallic target and a large bore, thin-walled tubular metal stem which, when connected to a rotor body assembly, provides a rotating x-ray tube anode assembly is disclosed. An insert of an alloy, for example, tantalum alloy, is placed between the target layer and the large bore, thin-walled tubular stem and then bonded thereto to produce a composite x-ray tube target/stem assembly. The target/stem assembly is then connected to a rotor body assembly by fasteners, preferably threaded, applied through a plate connected to the tubular stem and preferably through a thermal washer to produce a rotating anode assembly having high bond strength that provides acceptable balance during x-ray tube operations.

Abstract: The rotary cathode X-ray tube equipment of the present invention is constructed so as to permit radiation of X-ray from all directions with respect to the whole circumference of a subject, and is used for x-ray CT. The equipment of the invention is constructed to prevent an X-ray radiation window 40 of a low strength from being influenced by atmospheric deformations of a vacuum vessel 1 or by machining and assembling errors, for example by using a joint portion disposed between the X-ray radiation window and an inner ring and having both a surface perpendicular to a rotational axis of a rotary member and a cylindrical surface parallel to the rotational axis, a face seal formed on the surface of the joint portion perpendicular to the rotational axis, and an axial seal formed on the cylindrical surface of the joint portion parallel to the rotational axis.

Abstract: In an X-ray tube apparatus of a rotating anode type, a stator surrounds an anode rotary structure and an insulating container section placed around the outer periphery of a stationary structure such that a portion of its coil conductor located near the anode target side constitutes an expanding flared coil conductor portion. Therefore, it is possible, for the X-ray tube equipped with an envelope having a large-diameter metal section and small-diameter insulating container section, to shorten the axial length from an anode target of the X-ray tube to a far end of the rotary structure and to suppress the build-up of electric charges on the inner surface of the insulating container section.

Abstract: The invention relates to a device for driving the rotary anode of an X-ray tube, which device comprises a drive motor (5) having a stator (5a) and a rotor (5b), which are operated at anode potential, a rotor shaft (6) driving the rotary anode (7), the rotor (5b) of the drive motor (5) being constructed as an external rotor and the motor (5) being powered by means of a potential-isolating transmission means.

Abstract: An improved high performance x-ray system having a rotating anode therein which includes an improved coating for the x-ray tube rotor. The surface of the x-ray tube rotor is coated with a ductile coating wherein at least about 40,000 x-ray scan-seconds are accomplished prior to tube failure due to spalling. The coating may be a ductile alloy such as Rene' 80 having a thickness of about 0.2 to about 5.0 mils thick and may be even thicker. The rotor coating has ductile properties with a strain to fail greater than 0.05% and thermal expansion properties which when placed on an x-ray tube rotor, provides at least about 40,000 x-ray scan-seconds prior to tube failure due to rotor spalling.

Abstract: The motor efficiency of a rotating X-ray tube having an anode assembly and a cathode assembly, can be greatly improved. The improved efficiency x-ray tube motor comprises a stator and rotor assembly having an air gap between the stator and rotor. The improved efficiency is achieved by reducing the air gap. The stator is operated at anode potential and electrically connected through an anode high voltage cable.

Abstract: An electron beam scanning system producing an electron beam in a relatively short chamber includes an ion controlling electrode assembly located between the electron gun and system beam optics. The assembly includes a somewhat cone-shaped rotating field ion controlling electrode ("RICE") unit disposed between first and second ion controlling electrode units ("ICE"s). The RICE and ICEs each comprise element pairs symmetrically disposed on opposite sides of the chamber Z-axis, preferably forming regular polygons in cross-section. Preferably corresponding elements in each ICE are electrically coupled to each other and to an opposite element in the RICE. Preferably equal and opposite bias potentials, with respect to an average potential, are coupled to the RICE and ICE elements comprising an element pair. Because it is somewhat cone-shaped, the RICE and electron beam create a transverse electric field with no axial component.

Abstract: An x-ray tube rotor controller uses the main high voltage inverters for acceleration and speed maintenance. The rotor controller includes a DC voltage source, and a rotary anode drive circuit including a rotary anode motor designed as a two-winding induction motor. The rotor controller comprises first and second inverter circuits which may be either half bridge or full bridge arrangements, the first and second inverter circuits for accelerating the anode, and further for generating high voltage for the x-ray tube. Electronic switching means allow for instantaneous electronic switching of the output of the first and second inverter circuits between the high voltage power supply and the anode motor. A phase switching capacitor may be used to provide the other phase of the motor.

Abstract: X-ray tube noise is reduced by coupling the stator mass to the neck section of the glass vacuum tube so that vibrations are dissipated by the stator and not transmitted to the bulk of the vacuum tube. The coupling is accomplished with a non-magnetic sealing material such as an epoxy sealant. The sealant will generally fill the gap between the stator and the neck section of the vacuum tube. Alternatively, the coupling can be done with a mechanical clamping device.

Abstract: A rotary-anode X-ray tube having a rotor, a stationary shaft, and a sliding bearing connecting the rotor and the stationary shaft, forming a gap filled with liquid metal lubricant. The rotor has a first rotary member supporting an anode target and a second rotary member at which a sliding bearing is installed and which is coaxial with the first rotary member. The first and the second rotary members are connected at that end of the heat conductive path which is remote from the anode target. A heat insulating gap is formed at all fitting portions, but the remote end. Therefore, the temperature rise of the sliding bearing is controlled without using refregerant, and stable rotation of the bearing is secured.

Abstract: An x-ray tube (10) of a CT scanner has a rotating anode and rotor combination which is propelled by AC currents applied to run and phase windings (42, 46) by a starter (22). A monitor (24) includes Hall effect current detectors (40, 44) which detect the actual current flowing through the run and phase windings. The detected analog current values, voltage values, and the like are multiplexed (132) and digitized in a preselected order by an analog to digital converter (60) and stored in that order in a FIFO memory (62). A microprocessor (64) performs a Fourier transform (94, 96) to convert the digital run and phase signals into frequency spectra. The run and phase frequency spectra are compared (100, 102, 104, 106) with frequency spectra indicative of rotor speed, bearing wear, anode vibration, failure of the anode to rotate, and other conditions, analyzed for symmetry or other characteristics, or the like (FIG. 5 ) to generate digital run and phase reference signals.

Abstract: In X-ray tubes with a rotating anode, the shielding of the stator is obtained by a first conductive layer that is deposited on the external wall of an insulating bell-shaped part and has an electrical discontinuity, and by a second conductive layer that is deposited on the internal wall of an insulating cup-shaped or bowl-shaped part, the bell and the bowl encasing the stator and thus creating an electrostatic screen against the high frequency oscillations that result from the "crackling" of the tube. The device can be applied to X-ray tubes for radiology instruments.

Abstract: An X-ray imaging apparatus has a vacuum tube with an envelope that contains an anode, a cathode and a filament. A motor has a rotor mechanically connected to the anode inside the envelope and a stator on the exterior of the envelope. The vacuum tube and the motor are enclosed in an electrically conductive casing which are grounded. A grounded shield of a conductive material is placed between the stator and the envelope to suppress high voltage discharges within the envelope from producing currents in a winding of the stator. Low pass filters are placed in series with each conductor between the vacuum tube and a power supply to suppress radio frequency signals produced by the high voltage discharges from being carried over the conductors.

Abstract: A sationary rotatable anode (42) of an x-ray tube (10) is electrically connected to a high speed starter (24). The starter (24) includes an inductive rotor (44) connected to the anode (42), a main stator winding (50) and an auxiliary stator winding (52). The rotor (44) is driven by a power drive circuit (26) which is part of the starter (24). A main capacitor (64) is placed in series with the main winding for reducing its inductance. An auxiliary capacitor (66) is placed in series with the auxiliary winding for maintaining a selective impedence. A control circuit (90) is included in the starter (24) to control the main current and auxiliary current so that as the rotation of the rotor (44) increases, the control circuit (90) lowers the frequency of the main current and the auxiliary current passing to the main and auxiliary windings.

Abstract: In an X-ray tube wherein the rotor is supported by passive magnetic bearings, the respective positions of which are such that the rotor is offset in the direction opposite that of the anode, the bearings are mounted on an elastic system which has the effect of compensating for the axial component of the weight of the rotor and of the anode should the tube be tilted.

Abstract: An x-ray tube rotor structure wherein a target support stem has an externally threaded end portion engaged with an internally threaded surface of an encircling bushing and fixedly attached thereto by an interposed brazed joint. The stem is made of predominantly molybdenum material having a linear thermal expansion coefficient of 58.times.10.sup.-7 per degree Fahrenheit and is thermally matched with the bushing which is made of an iron cobalt nickel alloy material having a linear thermal expansion coefficient of 60.times.10.sup.-7 per degree Fahrenheit. The bushing has an outer surface fixedly attached through a welded joint with an inner surface of an annular plug which has an outer marginal portion fixedly attached to an adjacent end portion of a coaxial rotor skirt. The annular plug is made of an iron chrome nickel alloy material having a linear thermal expansion coefficient of 84.times.10.sup.

Abstract: An x-ray tube (10) imaging system, such as a computed tomography scanner, includes a cathode (40) for generating a stream of electrons. A rotating anode (42) is placed in a path of the electron stream and generates x-rays as a result of collisions therewith. An induction rotor (44) causes rotation of the anode as a result of electromagnetic interaction with a stator (48) comprised of two windings: a run winding (50) and a phase winding (52). The run winding and the phase winding are connected to three nodes (54, 58, 60), one of which is common to both. The three nodes are actively driven with run, common, and phase signals, respectively. Actively driving the three nodes increases bus drive voltage over 40% over that achieved by half-bridge drives.

Abstract: An X-ray tube comprises a generally cylindrical evacuated metal tube envelope having an anode rotatably mounted therein. [The interior of the tube envelope adjacent the anode is provided with ceramic insulation to prevent flashover.] The anode is rotated by an external variable speed DC drive motor magnetically coupled through the tube envelope wall to the rotating anode assembly. [The tube envelope wall includes ferrous segments which minimize the gap in the magnetic coupling while permitting a thick and strong tube envelope wall. A variable speed DC motor or a variable speed air motor may be employed to drive the anode. In preferred embodiments, the anode drive means is electromechanically clutched to the anode, whereby the drive means can be brought up to the desired anode speed and thereafter clutched to the anode, the drive means acting as a flywheel to bring the anode quickly up to speed. Electromagnets operating as clutches are also employed.

Abstract: In exemplary embodiments, the anode is driven by an induction motor, between the stator and rotor of which the wall of the vacuum envelope of the tube is disposed. To reduce the overall length and the lever actions of the weight of the anode which act on the bearing which are disadvantageous in this construction, the disclosure provides an annular anode which is disposed in the same plane with the drive rotor. The rotor and stator can here be surrounded by the ring of the anode or they can be secured externally about the latter. X-ray tubes in accordance with the disclosure are particularly suited for use for the purpose of medical x-ray examination.

Abstract: In an exemplary embodiment, the rotary anode is mounted by magnetic bearings and is provided with an auxiliary device for conducting the anode current to the external power supply. The auxiliary device comprises at least one auxiliary cathode which rotates with the anode and an auxiliary anode which is arranged concentrically to the anode rotary axis on a stationary part. The heating of the auxiliary cathodes can proceed via generator windings which rotate with the rotary anode and associated stationary exciting windings arranged about the x-ray tube. It is also possible to provide for this purpose a rotating transformer whose primary windings externally annularly surrounds the x-ray tube and whose secondary winding is arranged on a rotating anode part.

Abstract: In an exemplary embodiment, an anode assembly is magnetically mounted free of contact. In order to carry off the anode current, on a part rotating with the anode assembly, an auxiliary cathode is arranged opposite which a stationary auxiliary anode is disposed. The auxiliary cathode is an oxide cathode which is centrically arranged on the rotary anode assembly and opposite which a stationary heater is disposed.