JPS61279049A - Magnetic levitation type x-ray tube device - Google Patents

Abstract

PURPOSE:To realize a magnetic levitating action with a high accuracy, by furnishing an intermittent contact device to contact softly and intermittently to a portion of the peripheral metallic tube body of a rotor, at a portion of a vacuum container around the rotor, which supports a rotary anode target. CONSTITUTION:At a portion of a smaller diameter container 13 of a vacuum container 11 around a rotor 15, an intermittent contact device 41 is installed airtight in a vacuum. While the rotor 15 is rotating, a current flows in the electromagnetic coil, a movable rod is pulled to a core against the elasticity of a spring, the current to the coil is cut off in a very short time with a long interval, and a contactor 48 contacts softly and intermittently to a metal ring 26a of the rotor 15. To an anode target 16, a high potential is kept to apply constantly, and the off and on control of the electron beams is performed by a control grid of a cathode fitting 17. Therefore, the rotor can be kept in a magnetic levitation almost perfectly and rotated at a high speed.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an X-ray tube device, and particularly relates to an improvement in a magnetic levitation height X-ray tube device in which a rotating anode tardat structure is levitated and rotated by magnetic force. .

[Technical background of the invention and its problems] As for this type of magnetic levitation X-ray tube device, the configurations disclosed in Japanese Patent Laid-Open No. 52-89088 and Japanese Patent Laid-Open No. 53-136988 are already known. It is being The structure shown in these is a structure in which voltage is constantly supplied to the outer peripheral metal cylinder part of the rotating anode target or rotor through a contact device that is in contact with it, or a structure in which it is brought into contact with a metal vacuum container to provide a ground potential. . For this reason, the feature of the magnetically levitated X-ray tube apparatus, which is a non-contact structure, is lost, and the life characteristics are disadvantageously sacrificed.

[Purpose of the invention]

The present invention provides a magnetic levitation X-ray tube device that eliminates the above-mentioned disadvantages, suppresses abnormal discharge between the outer peripheral metal cylindrical portion of the rotor and the vacuum vessel, and has a longer service life.

[Summary of the invention]

This invention is characterized in that a part of a vacuum container surrounding a rotor that supports a rotating anode target is provided with an intermittent contact device that makes soft contact intermittently with a part of an outer metal cylindrical body of the rotor. This is a floating height X-ray tube device. In this case, by bringing the contacts of the intermittent contact device into contact with the outer metal cylinder of the rotor for a very short period of time at long intervals, it is possible to release the electric charges on the metal cylinder and maintain it at ground potential, thereby making it possible to connect the rotor and the vacuum vessel. The gap between them can be made as small as possible.

[0 Example of invention] Examples thereof will be described below with reference to the drawings.

Note that the same parts are designated by the same symbols.

The embodiment shown in FIGS. 1 and 2 has the following structure. The vacuum vessel of the X-ray tube main body portion includes a thick-walled, large-diameter metal portion 12, a thin-walled, small-diameter container portion 13, and a ceramic stem portion 14. A rotor is provided inside the small-diameter container portion 13, and a rotating anode target 16 is fixed to the tip thereof. Cathode structure 17 facing the target
is fixed to the ceramic disk 18f. This cathode structure 17 includes an electron emitting filament 19. It has an electron beam control grid 20. An X-ray emission port 21 for emitting an X-ray beam is provided in a part of the thick-walled large-diameter portion 12 . The rotary includes a ceramic insulating tube 22, a conductive sleeve 23 inserted into its center hole, a metal ring 24 for target connection, a conductive connection plate 25, and a metal tube 26 fitted around the outer periphery. Laminated plate made of ferromagnetic material 2
7. Non-magnetic metal tube 28, hot cathode tube 29 for anode current path
, it has wavy portions 3oa and sob for increasing the insulation creepage distance. Inside the heat shield tube 29, 7 nodes 3 which also serve as heaters are provided in close proximity to each other in a non-contact manner.
A lead wire is led out through 4. The rotor 15 is attached to
A control position detector 34 is also provided. Note that the end portion of the small diameter container portion 13 is held by a support frame 35.

Therefore, the small diameter container part 13 of the vacuum container that blows up the rotor U
An intermittent contact device (3) is installed in a vacuum-tight manner in a part of the unit. In this intermittent contact device U, the envelope 42 is
3, and an electromagnetic coil 43 is installed inside it.
, core 44, movable rod 45, spring 46, movable/
4' lead 47, contact 48 made of metal with good wear resistance
is provided. The movable mother, Do 47, is its arm 4.
9 is movably supported by a stator 5o, and the stator 5o is connected to a lead 51. On the other hand, a metal ring 26a with good wear resistance is fixed to a portion of the metal cylinder fitted around the outer periphery of the insulating cylinder 22, which corresponds to the contact 48tlC. While the rotor U is rotating, as shown in the figure, the electromagnetic coil is energized and the movable rod is drawn toward the core against the elastic force of the spring, and as will be explained next, the electromagnetic coil is energized and the movable rod is drawn toward the core at long intervals and at very short intervals, as will be explained next. The current to the coil is cut off for a certain amount of time so that the contactor makes soft contact with the metal ring of the rotor D intermittently.

In operation of this X-ray tube device, a high potential of, for example, 75 kV is applied to the target K through an anode energizing diode consisting of an anode 3 fixed to the stem and serving as a heater and a hot cathode cylinder 29 of the rotor. The vacuum vessel is operated at ground potential, and a negative voltage, for example 75 kV, is applied to the cathode structure. The outer peripheral metal cylindrical portions of the rotor L are suspended in air by the insulating cylinder and gradually become electrically charged. When this is expressed as an electrical equivalent circuit, it becomes as shown in Fig. 3. In the figure, reference numeral 13.
Reference numeral 13 corresponds to a metal vacuum vessel part, 23 corresponds to a part of a conductor sleeve to which an anode potential is applied, and 26a corresponds to a metal cylinder part on the outer periphery of the rotor. The impedance Za is a high resistance component and a capacitive reactance component of the insulating cylinder 22, and the impedance zb is a high resistance component and a capacitive reactance component that are present in the gap between the metal cylinder of the rotor and the vacuum vessel portion.

For example, if a silicon nitride ceramic with a diameter of 30 m is used as the insulating cylinder, the resistance component of the impedance Za is approximately 1.
0 Ω, the capacitive component is approximately equivalent to 10-10F.

Further, assuming that the vacuum gap between the outer peripheral metal cylinder of the rotor and the vacuum vessel is approximately 0.5 mm, the high resistance component of the equivalent impedance zb approximates approximately 10 Ω, and the capacitance component approximates approximately 10 Ω.

When a potential of 75 kV is applied to the anode target as described above, the potential of each metal cylinder portion 26,28 increases exponentially with a very large time constant, as shown in FIG. This time constant is approximately 50 minutes. Considering the withstand voltage between the metal cylindrical body of the rotor 2 and the vacuum vessel, it is sufficient to release the electric charges on the outer circumferential metal cylindrical body within several minutes. Therefore, the electromagnet is controlled so as to drive the movable rod in a short period of time to bring the movable contact into contact with the metal ring 26& of the second rotor at intervals of about this time. It is preferable that a high potential is always applied to the anode target, and that the intermittent control of the electron beam is controlled by the control grid of the cathode structure.
It is desirable to connect a noise suppression circuit 6 as shown in FIG. 5 between the vacuum vessel portion and the ground potential. This circuit 61 includes a discharge gap G, a surge absorption element D, and protection resistors R1 and R2 connected in parallel.

This makes it possible to suppress contact noise when the movable contactor contacts the metal cylindrical body of rotor 2, and to suppress adverse effects on each member for controlling magnetic levitation.

In the embodiment shown in FIG. 6, the intermittent contact device port is configured such that a movable rod 45 and a movable knot 47 move in an oblique direction.

Further, in the embodiment shown in FIG. 7, an intermittent contact device opening having a double goal bearing 71 is provided in a part of the vacuum vessel 13, and the intermittent contact device opening is moved intermittently by a drive device (not shown) as shown by an arrow f. The outer periphery is configured to be in soft contact with a part of the metal cylindrical body 26 of the rotor itself.

〔Effect of the invention〕

As explained above, according to the present invention, the rotor can be almost completely magnetically levitated and rotated at high speed, and the magnetic levitation on the outer circumference of the rotor and the charge on the outer circumferential metal cylinder for rotational driving can be intermittently reduced. Since the metal cylinder can be released and kept at a relatively low potential at all times, the gap between the metal cylinder and the metal vacuum container surrounding it can be made small, and magnetic levitation and rotation control are efficient. Therefore, highly accurate magnetic levitation operation can be obtained.

[Brief explanation of drawings]

Fig. 1 is a vertical cross-sectional view of main parts showing one embodiment of the present invention;
The figure is an enlarged sectional view of the main part, Figure 3 is its equivalent circuit, and Figure 4
5 is a grounding circuit diagram, FIG. 6 is a sectional view of a main part showing another embodiment of the present invention, and FIG. 7 is a main part showing still another embodiment of the invention. FIG. L...Vacuum container, 13...Small diameter container part, J5-...
・Rotor, 16... Anode target, 17... Cathode structure, 22... Insulating tube, 23... Conductor sleeve, 26.27.28... Metal cylinder, 41... Intermittent contact Device, ° 47... Movable pad, 48... Contactor. Applicant's Representative Patent Attorney Takehiko Suzue Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7rlA

Claims (1)

[Scope of Claims] A rotating anode target is supported by a rotor inside a vacuum vessel, and a solenoid for levitating the rotor by magnetic force and a stator for rotational driving are arranged on the outer periphery of the vacuum vessel corresponding to the rotor. , in a magnetic levitation X-ray tube device in which the rotor has an insulating cylinder and a metal cylinder fitted around its outer periphery, a portion of the metal cylinder of the rotor is intermittently softened in a part of the vacuum vessel; A magnetic levitation X-ray tube device, characterized in that it is provided with an intermittent contact device.