JPH05129092A - Device for feeding electric power to rotating body - Google Patents

Abstract

PURPOSE:To prevent generation of friction at a power supply portion so as to increase reliability by generating a magnetic field within an envelope and moving a conductor disposed on a rotating body within the magnetic field thereby supplying electric power to a rotating body without contact. CONSTITUTION:A fixed magnetic field generating device 7 including two ring- type permanent magnets is fixed inside an envelope 1 to produce a fixed magnetic field. A tank 6 containing a molten metal 5 is mounted on a rotating body 4. When the rotating body 4 rotates, the tank 6 and the metal 5 move within a fixed magnetic field to generate an electro-motive force within the metal 5 due to electromagnetic induction thereby an electric current is generated between electrodes 8. This current is supplied to a filament 2 and the thermal electrons emitted from the filament 2 collide with an anode 3 so as to generate X-ray. Thereby, wear and dust are not generated so as to increase reliability and at the same time to assure a longer life.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for a rotating body which is suitable for supplying power to a rotary cathode provided in a rotary cathode type X-ray tube device.

[0002]

2. Description of the Related Art A rotating cathode type X-ray tube device recently proposed for ultra-high speed X-ray CT is an X-ray tube formed in a donut shape so as to surround the periphery of a subject, and is an annular vacuum chamber. A rotating body provided with a cathode filament is arranged in an envelope for rotation, and a ring-shaped fixed anode is fixed to the annular vacuum envelope so as to face the rotating body. The cathode filament rotates with the rotation of the rotating body, and the collision position of the electron flow colliding with the ring-shaped fixed anode moves in the circumferential direction of the ring-shaped fixed anode, whereby the emission position of the X-ray emitted toward the subject. Moves at high speed around the subject.

Conventionally, in such a rotary cathode type X-ray tube device, power is supplied to the rotating body by sliding a power supply brush to a slip ring attached to the rotating body.

[0004]

However, in the above-described conventional power feeding device for a rotating body, dust is generated due to wear of the power feeding brush and is dispersed in the vacuum envelope, so that the dust of the vacuum envelope is not generated. There are problems that the degree of vacuum is lowered and the withstand voltage performance is deteriorated. In addition, the conventional power supply device has a problem that its life is relatively short due to wear of the power supply part.

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide a power feeding device for a rotating body, which is improved so as not to cause wear at a power feeding portion.

[0006]

In order to achieve the above object, in a power feeding device for a rotating body according to the present invention, a magnetic field generating device is provided in an envelope in which the rotating body is housed, and the magnetic field is generated in the magnetic field. It is characterized in that the conductor provided on the rotating body is moved so that a current flows through this conductor by an electromotive force due to electromagnetic induction. Thus, it is possible to apply power to the rotating body without contact. Therefore, there is no problem of abrasion and dust associated therewith, reliability can be improved, and life can be extended.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is an ultra-high speed X-ray CT to which a power feeding device for a rotating body according to an embodiment of the present invention is applied.
1 shows a rotary cathode type X-ray tube device for use in the present invention. In FIG. 1, the envelope 1 is made of, for example, stainless steel in an annular shape and is evacuated. A subject (not shown) is inserted into the center hole 11.

In this envelope 1, a ring-shaped rotating body 4 is provided.
, And is magnetically levitated by an electromagnet (not shown), and is rotationally driven at, for example, 10 Hz by an induction motor (not shown). One cathode filament 2 made of, for example, tungsten is fixed to one point of this rotating body 4. This filament 2 rotates with the rotation of the rotating body 4 and draws a circular orbit. A ring-shaped anode 3 is fixed inside the envelope 1 so as to face the circular orbit. When electrons are generated from the filament 2 and collide with the facing anode 3, X-rays are generated and emitted in the direction of the central hole 11, and the subject in the central hole 11 is irradiated with X-rays. When the rotator 4 rotates, the filament 2 also rotates and the electron collision position rotates, so that the X-ray focal point circulates around the subject.

A constant magnetic field generator 7 composed of two concentric ring-shaped permanent magnets is fixed inside the envelope 1, and the direction of magnetic flux is the radial direction passing through the central axis of the envelope 1. A constant magnetic field is created.

On the other hand, a tank 6 containing a molten metal 5 is attached to the rotating body 4. This tank 6 is of a ring type, and is placed in a position such that it is sandwiched between the two ring type permanent magnets of the constant magnetic field generator 7 and is placed in a constant magnetic field. When the rotating body 4 rotates, the tank 6 and the molten metal 5 move in this constant magnetic field. Then, electromotive force is generated in the molten metal 5 by electromagnetic induction, and the direction of the magnetic field (upward and downward in the figure)
And an electric current is generated between the electrodes 8 arranged at right angles to both the moving direction (the direction perpendicular to the paper surface in the figure). This current is supplied to the filament 2, and thermoelectrons are emitted from the filament 2, and the thermoelectrons collide with the anode 3 to generate X-rays.

The above-mentioned power generation is so-called MHD power generation, and its principle will be described with reference to FIG. In this figure, it is assumed that the fluid 22 having the conductivity σ and the permeability μ flows in the container 21 at the velocity U (vector) to the left and right, and the magnetic field B (vector) is applied from the back side of the paper toward the front side. I shall. At this time, the induced electric field E (vector)
Becomes E = U × B, and the electric current I is applied to the load Rm through the electrode 23 arranged in the electric field direction (direction perpendicular to U and B, vertical direction in the figure).
m flows. At this time, the current density j (scalar) and the output density Pd (scalar) are j = (1-k) σμB Pd = k (1-k) σU ² B ² (U and B are scalars here) (k; Load factor = Rm /
(Rm + Ri)). The container 21 is the tank 6 in FIG.
And the fluid 22 corresponds to the molten metal 5 in FIG.
m corresponds to the filament 2 in FIG.

In addition to the molten metal 5 as described above, a spiral coil or a metal block may be used as the conductor that generates an electromotive force by moving in a constant magnetic field as the rotor 4 rotates. You can Further, as a device for generating a constant magnetic field, an electromagnet, a superconducting magnet, or the like can be used in addition to the device using the permanent magnet as described above.

[0013]

As described in the above embodiments, according to the power feeding device for the rotating body of the present invention, the conductor provided on the rotating body moves into the magnetic field of the magnetic field generator provided on the fixed side. Since electromotive force is generated by electromagnetic induction, power can be applied to the rotating body in a completely non-contact manner, wear and dust do not occur, reliability can be improved, and life is extended. Can be planned.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of a power feeding device for a rotating body according to the present invention.

FIG. 2 is a schematic sectional view showing the principle of power generation.

[Explanation of symbols]

 1 Enclosure 11 Central Hole 2 Filament 3 Anode 4 Rotating Body 5 Molten Metal 6 Tank 7 Constant Magnetic Field Generator 8 Electrode 21 Container 22 Fluid 23 Electrode

Claims (1)

[Claims] 1. An envelope, a rotating body that rotates in the envelope, a magnetic field generator fixed in the envelope, and the rotating body, which is provided in the rotating body and is rotated in the magnetic field. And a conductor that generates an electromotive force by electromagnetic induction by moving the electric power supply device to the rotating body.