JPS5816744B2 - Rotating anode type X-ray tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotating anode type X-ray tube, and particularly to improvements in its rotation mechanism.

Generally, X-ray tubes are used for medical purposes, for example, for X-ray diagnosis, but in cases such as stomach examinations, an X-ray tube as shown in Figure 1 is conventionally used. This is a so-called rotating anode type device, in which a cathode 2 is disposed on one side of an envelope 1, and a cup 3 containing a cathode filament and a focusing electrode is provided eccentrically.

Further, an anode 4 is disposed near the center of the envelope 1 facing the cathode 2, and a substantially umbrella-shaped target 5 of the anode 4 is rotated by a rotor 6 via a support column 7. There is.

During operation, a high voltage (30 to 200 k) is applied between the cathode and anode.
v) is applied, and the electrons emitted from the cathode filament are focused by the focusing electrode to form two focal points, large and small, on the target 5, and the small focus is used for fluoroscopy and the large focus is used for photographing.

By the way, the main parts (near the rotation mechanism) of a conventional rotating anode type X-ray tube are shown in FIG.
Nut 8 fixes the anode target 5 to the support column 7;
is a covered cylindrical rotor that is integrated with the support column 7.

Further, the rotating shaft has a disk 10 at one end thereof, and the disk 10 is fixed to the rotor 6 with a screw 11.

Therefore, when the rotating shaft 9 rotates, the anode target 5 also rotates.

The bearings 12 and 13 are cylindrical stators.

Further, 15 and 16 are cylindrical spacers that support the bearings 12 and 13 at predetermined intervals, and 17 is a nut.

Incidentally, the above-mentioned 6.7 and 9 constitute a rotor.

During actual use, the rotor 6 of the rotor receives a rotating magnetic field from the outside, and the anode target 5 is rotated by this force.

By the way, rotating anode X-ray tubes usually have an anode target 5.
It is used by rotating at a speed of 3000 to 9000 rpm.

The input power applied to the X-ray tube is applied to the surface of the target 5, generating heat.

Most of this heat becomes radiant heat from the surface of the target 5 and the surface of the rotor 6 and is taken out of the tube, but some of the heat increases the temperature of the rotating shaft 9.

In general, the rotating shaft 9 is constantly subjected to loads due to the weight and dynamic balance of the rotating body during rotation and when moving while rotating.For this reason, a material with high high temperature strength is selected and used for the rotating shaft 9. has been done.

On the other hand, metal is selected for this rotating shaft 9 because it requires a function to take out the X-ray tube current applied to the target 5 outside the tube via bearings 12 and 13, and SUS material is usually used. The high-temperature mechanical strength of the rotating shaft 9 suppresses the input to the X-ray tube.

Therefore, in order to increase the mechanical strength of the rotating shaft 9 using the same material,
It is conceivable to increase the diameter of the rotating shaft 9, but in this case, because the diameter of the hair ring 12.13 is increased, the circumferential speed of the bearing ball will increase, and the bearing 12.13 will increase in diameter.
This has the drawbacks of shortening the service life of the rotor, and increasing rotational vibration noise due to the need to enlarge the gap.

This invention was made in view of the above circumstances, and an object of the present invention is to provide a rotating anode type X-ray tube with improved performance by using a ceramic silicon nitride material with excellent high-temperature strength for the rotating shaft. shall be.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

The rotating anode type X-ray tube of the present invention is constructed as shown in FIG. 3, and the same parts as those in the conventional example (FIG. 2) are denoted by the same symbols. A rotating shaft 19 is coaxially fixed via a conductor 18.

In this case, the conductor 18 is shaped like a rod and has a disk 21 at one end with a plurality of tapped holes 20, as shown in FIG.

Further, a disk 22 is integrally formed at one end of the rotating shaft 19, and this disk 22 and the disk 21 of the conductor 18 are fixed to the inner surface of the lid portion of the rotor 6 by screws 11. .

The rotating shaft 19 is made of silicon nitride (SIN) material, for example, Si3N4.

This Si3N4 is ceramic, has a blackish color, and has excellent heat radiation.

As shown in the figure, the heat generated in the target 5 is conducted to the bearing via the support column 7 and the rotating shaft, but a rotating shaft 19 made of silicon nitride material is interposed in this heat transfer path6 However, this Si3N4 Since it is not an electrical conductor, the conductor 18 is passed through the rotating shaft 19 as shown in the figure, and one end of the conductor 18 is electrically connected to the bearing inner ring tightening nut 17 via a metal piece 23. The rotor 6 and the bearing 13 are electrically connected.

In other words, it has the function of transmitting the X-ray tube current to the inner ring of the bearing.

A cylindrical stator 14 is provided between the rotating shaft 19 and the rotor 6.
is inserted therein, and the stator 14 is fixed to a vacuum envelope (not shown).

Two sets of bearings 12.13 are interposed between the stator 14 and the rotating shaft 19, and these bearings 12.13 are supported and maintained at a predetermined distance by cylindrical spacers 15.16. .

The rotating anode type X-ray tube of the present invention is constructed as described above and shown in the drawings, and the rotating shaft 19 is made of silicon nitride (SIN).
) material, as shown in Figure 5, compared to the conventional S
Superior high-temperature strength can be obtained compared to US materials.

As a result, rotational performance and strength at high temperatures are significantly improved,
The input power of the x-ray tube can be increased.

Incidentally, FIGS. 6 and 7 show a modification of this invention, and the same effect as the above embodiment can be obtained.

That is, in the case of FIG. 6, a cylindrical conductor 24 is arranged around the outer periphery of the rotating shaft 19, contrary to the above embodiment.

Further, in FIG. 7, a plate-shaped conductor 25 is closely interposed between the screw 11 and the bearing 12, thereby simplifying the structure.

As explained above, according to the present invention, a rotating anode type X-ray tube of great practical value can be provided.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing a conventional rotating anode X-ray tube used to explain the present invention, FIG. 2 is a sectional view showing the vicinity of the rotation mechanism in a conventional rotating anode X-ray tube, and FIG. 4 is a sectional view showing the vicinity of the rotating mechanism in a rotating anode type X-ray tube according to an embodiment of the present invention, FIG. 4 is a perspective view showing a conductor used in the rotating mechanism of FIG. 3, and FIG. FIGS. 6 and 7 are characteristic curve diagrams showing the strength characteristics against hot water temperature of the material of each rotating shaft in the X-ray tube, and FIGS. 6 and 7 are cross-sectional views showing modifications of the present invention. 5...Anode target, 6...Rotor, 7...Support column, 11...Screw, 1
2, 13... Bearing, 14... Stator, 17... Nut, 18... Conductor, 19... Rotating shaft, 20 ...screw hole,
21...disc, 23...metal piece.

Claims (1)

[Scope of Claims] 1. A rotating anode X-ray tube that supports an anode target, has a rotating shaft that is integrally fixed to a cylindrical rotor, and is rotatably held relative to a stator via a bearing, A rotating anode in which the rotating shaft is made of a silicon nitride material, a conductor is disposed inside or on the outer surface of the rotating shaft, and an electrical connection path is formed between the bearing and the anode target via the conductor. type x-ray tube.