JPH07176284A - Power supply device for rotating body - Google Patents

Abstract

(57) [Summary] [Purpose] Power is supplied to the rotating body without causing wear. [Structure] A low-melting metal is arranged in a ring shape inside an envelope. On the other hand, an edge-shaped electrode is attached to a rotating body that rotates in the envelope, and the tip of the edge-shaped electrode slides while contacting the ring-shaped low-melting-point metal as the rotating body rotates, resulting in a ring shape. Move along.

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 rotary 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. 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 X-ray emission position is 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 There are problems that the degree of vacuum is lowered and the withstand voltage performance is deteriorated. In addition, the conventional power feeding device has a problem that the life of the power feeding portion is relatively short due to wear of the power feeding portion.

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 relatively high melting point is provided inside the envelope or on one side of the rotating body rotating therein. Is attached to the conductive metal that is low and is kept at a temperature below this melting point, and an edge-shaped electrode is attached to the other side, and the edge-shaped electrode is rotating during rotation of the rotating body.
The feature is that the conductive metal is brought into contact with the conductive metal substantially constantly. The tip of the edge-shaped electrode slides while coming into contact with the above conductive metal as the rotating body rotates, but at that time, the low-melting-point metal in the contacting portion is melted and the molten metal is excellent. It becomes a lubricant, and the tip of the edge-shaped electrode can be moved in contact with it without wear. As a result, it is possible to avoid problems such as wear and dust associated therewith, improve reliability, and extend the life, while supplying power to the rotating body by contact between the tip of the edge electrode and the low melting point metal.

[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 shows a rotating cathode type X-ray tube device for ultra-high speed X-ray CT to which a power feeding device for a rotating body according to a first embodiment of the present invention is applied. 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. The 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 object 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.

Inside the envelope 1, a container 6 having two concentric tanks is fixed, and gallium (G
a) Metal 5 is stored. The container 6 is made of an insulating material. Therefore, the gallium metal 5 stored in each tank of the container 6 has a ring shape so as to form concentric circles. The container 6 is open on the left side of the drawing, and two concentric openings are formed. The surface of the gallium metal 5 is exposed from the two concentric openings.

The gallium metal 5 has a melting point of 30 ° C. and has a relatively low melting point. Gallium metal 5
A cooling device 8 is attached to the outside of the envelope 1 in order to maintain the temperature below its melting point. Therefore, the gallium metal 5 remains in the container 6 as a solid without melting.

On the other hand, two edge-shaped electrodes 7 are attached to the rotating body 4, and the tips of these edge-shaped electrodes 7 are brought into contact with the two concentric ring-shaped gallium metals 5. When the rotating body 4 rotates, these 2
One edge-shaped electrode 7 comes into contact with the surfaces of the two ring-shaped gallium metals 5 and slides and moves. As a material of the edge-shaped electrode 7, for example, a metal having a relatively high electric resistance such as SUS304 is used, and a contact electric resistance with the gallium metal 5 is increased to generate Joule heat, and the edge of the edge-shaped metal 7 is It is desirable to increase only the temperature of the contact portion with the gallium metal 5. Further, it is desirable that the cross-sectional shape of the tip of the edge-shaped electrode 7 be the same as the cross-section of the edge of the ice skates.

As a result, when the tip of the edge-shaped electrode 7 moves in contact with the surface of the gallium metal 5, the narrow portion of the gallium metal 5 near the contact portion melts at a temperature equal to or higher than the melting point and melts the molten metal. Becomes a lubricant and makes smooth contact movement. As a result, sliding contact between the edge-shaped electrode 7 and the gallium metal 5 can be realized without wearing, and power can be supplied to the rotating body 4 (filament 2) by this sliding contact. A coil spring or the like may be provided on the edge-shaped electrode 7 so as to impart appropriate elasticity to be pressed against the gallium metal 5 side.

Thus, the electric current is passed from the power source 9 to the filament 2 to heat it. On the other hand, gallium metal 5 and anode 3
A high voltage generator (not shown) is connected between and to form a high potential difference between the filament 2 and the anode 3.
Therefore, the thermoelectrons emitted from the filament 2 are transferred to the anode 3
And an X-ray is generated.

As the low melting point metal which comes into contact with the edge-shaped electrode 7, in addition to the above-mentioned gallium having a melting point of 30 ° C., gallium-indium (Ga-In) having a melting point of 17 ° C.
Alloys and gallium / indium / tin (Ga-In) at 5 ℃
A —Sn) alloy, indium (In) at 160 ° C., or the like can be used. However, in the case of indium, the melting point is rather high, so it is preferable to heat the tip of the edge electrode 7 with another heater or the like in order to melt it at the contact portion with the edge electrode 7.

FIG. 2 shows a modified example, in which the gallium metals 51 and 52 and the containers 61 and 62 for housing them are fixed to the envelope 1 side so as to face each other. Edge electrodes 71 and 72 are attached to the rotating body 4 side so as to face the facing gallium metals 51 and 52, respectively, via a coil spring. In this way, the edge-shaped electrode 71,
Since 72 is configured to be sandwiched between the two gallium metals 51 and 52, even if a shake occurs when the rotating body 4 rotates, the edge-shaped electrode 71 and the gallium metal 51 or the edge-shaped electrode 72 The contact with either one of the gallium metal 52 will be maintained, and stable power supply to the rotating body 4 is possible.

In all of the above, the ring-shaped low melting point metal is provided on the fixed side and the edge-shaped electrode is provided on the rotating side. On the contrary, the ring type low melting point metal is provided on the rotating side and the edge side electrode is provided on the fixed side. It is also possible to provide edge-shaped electrodes. That is, in the modification shown in FIG. 3, the container 63 is attached to the side of the rotating body 4, and the two ring-shaped indium metals 53 and 54 are housed in the container 63. Then, the edge-shaped electrode 73 is fixed to the envelope 1, and the tip of the edge-shaped electrode 73 is brought into contact with the surfaces of the indium metals 53 and 54.
When the low melting point metal is attached to the rotating side as described above, it is difficult to cool the low melting point metal, and thus a metal such as indium having a slightly higher melting point is preferable. Then, the edge metal 73 is heated by the heater 74 so that it melts at the contact portion of the indium metal 53, 54 with the edge electrode 73. Indium metal 53, 5
If 4 is attached to the rotating side, the molten metal may be scattered by the centrifugal force during the rotation. Therefore, as shown in FIG. 3, the container 63 is placed outside with respect to the center of rotation.
Of the molten indium metal 5 by arranging the openings of the
Centrifugal force rather pulls 3, 54 to the inside of the container 63 so that drips and the like do not fall.

In each of the above embodiments, the low-melting-point metal side is ring-shaped and the edge-shaped electrode slides on the surface thereof. On the contrary, the edge-shaped electrode is ring-shaped. It goes without saying that the low melting point metal may be provided at one point of the rotation angle so that the surface of the low melting point metal slides while contacting the ring-shaped edge electrode.

[0018]

As described in the above embodiments, according to the power feeding device for a rotating body of the present invention, it is possible to feed power to the rotating body from the fixed side by a very smooth sliding contact. Unlike the case where power is supplied using a slide mechanism including a slip ring and a brush, wear and dust are not generated at the power supply portion, reliability can be improved, and life can be extended.

[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 a modified example.

FIG. 3 is a schematic cross-sectional view showing another modification.

[Explanation of symbols]

 1 envelope 11 center hole 2 filament 3 anode 4 rotor 5,51,52 gallium metal 53,54 indium metal 6,61,62,63 container 7,71,72,73 edge-shaped electrode 8 cooling device 9 power supply

Claims (1)

[Claims] 1. An envelope, a rotating body that rotates in the envelope, and a relatively low melting point attached to one of the inside of the envelope and the rotating body, and to a temperature below the melting point. A conductive metal that is held; and an edge-shaped electrode that is attached to the inside of the envelope and the other of the rotating body so that the conductive metal is in constant contact with the conductive metal during rotation of the rotating body. A power supply device for a rotating body, which is characterized in that