JPS60163355A - X-ray tube - Google Patents

Abstract

PURPOSE:To keep a rotary drive section free from the effect of electromagnetic waves or heat from a rotary anode by placing a shield member made of a conductive and high thermal reflexibility material between a rotary anode and its rotary drive section. CONSTITUTION:In the joint area of partitions 1a, 1b of a vacuum enclosure 1 is fixed a shield member 3 (made of a conductive material such as molybdenum) which has a high thermal reflexibility coating material applied on its surface; a cathode 7 and a rotary anode 8 are arranged in the partition 1a, and in the partition 1b is installed a rotary drive mechanism 10 consisting of one element, which drives a rotor 11 connected to the rotary anode 8 from the outside, and another element, which supports the rotor 11 by the magnetic force with no mechanical contact; this is the way a rotary anode type X-ray tube is formed. Therefore, the electromagnetic waves and heat emitted from the rotary anode 8 are prevented from being transmitted to the rotary drive mechanism 10 by the shield member 3, thus ensuring the smooth rotation by the stable position control all the time.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an X-ray tube device, and in particular, to an X-ray tube device, in which an anode is rotated and a rotor that rotates the anode is completely non-contacted by a rotation drive unit. The present invention relates to an improvement in an X-ray tube device that is supported and rotatably driven.

[Background technology of the invention]

Structurally, X-ray tube devices are roughly divided into fixed anode types and rotating anode types. Since the anode of the rotating anode type rotates, the effective area of the heat load applied to the anode can be increased, which has the advantage of being able to withstand momentary large loads.

Incidentally, in a rotating anode type X-ray tube device, the higher the rotation speed of the anode, the more the anode can be protected from heavy loads. Therefore, when applying a large load to the anode, it is necessary to rotate the anode as fast as possible. In this way, a high-speed rotational drive source is required to rotate the anode at high speed, but when the rotor of this rotational drive source is supported by a mechanical bearing device, the rotation speed is normally at most 10,000 rotations per minute. The extent is the limit. Also, when using a mechanical bearing device, if you try to increase the rotation speed to the specified speed in a short time,
The life of the bearing, which requires a large amount of power, will be significantly shortened, and since the bearing device must be installed in a vacuum container where the cathode and anode are located, the life of the entire device will also be shortened. However, there is a problem in that the noise generated by the rotating contact of the mechanical bearings is too large to be used for medical purposes.

Therefore, in order to solve this problem, recently it has been proposed that the rotor supporting the rotating anode is supported in a completely non-contact manner by magnetic force supplied from outside the vacuum container. In other words, in the magnetic bearing type device, a ring made of a high magnetic permeability material is attached to the rotor, and a permanent magnet for supplying magnetic force for magnetic support is placed outside the vacuum vessel. The rotor is moved in the axial direction by passing the magnetic flux emitted from the ring through a path from a permanent magnet to a yoke with a magnetic pole provided outside the Ringle vacuum vessel to a permanent magnet.
It supports completely non-contact in both radial directions.

[Problems with background technology]

As mentioned above, in the case where the rotor that supports the rotation @ poles is supported by the magnetic force of permanent magnets, the following rotor position control is required in order to always stably support the rotor. will be held.

That is, in the above device, a coil is attached to the magnetic pole, and a non-contact displacement detector is provided at a position facing the rotor outside the vacuum container.

This detector constantly monitors the axial and radial positions of the rotor, and the fill is energized based on the signal from the detector. This allows the rotor to have its displacement appropriately corrected and to be stably supported at all times.

However, the non-contact displacement detector generally has the property of responding very sensitively to electromagnetic waves such as X-rays. Therefore, in devices such as the above-mentioned device in which the rotating anode and the non-contact displacement detector are placed relatively close to each other, the influence of X-rays scattered inside the container and entering the detector cannot be ignored. This was one of the causes of instability in stably supporting the rotor.

In addition, when this type of X-ray tube device is in operation,
The electron irradiation surface of the rotating anode reaches a high temperature of several hundred degrees. Therefore, the heat generated at the rotating anode is transferred to the rotor by radiation or thermal conduction, which significantly increases the temperature of the entire rotating drive section. As a result, the characteristics of the magnet deteriorate and the detection performance of the non-contact displacement detector deteriorates, which becomes another factor that impairs the stable support of the rotor.

[Purpose of the invention]

The present invention has been made based on the above points, and an object of the present invention is to suppress the direct influence of electromagnetic waves or heat emitted from the rotating anode on the rotating drive part, and thereby An object of the present invention is to provide an X-ray tube device that can be rotated at a stable position at all times.

[Summary of the invention]

The present invention has a rotating anode that emits X-rays when electrons emitted from the cathode collide with each other, a rotor that supports the rotating anode, an element that supports the rotor completely non-contact by magnetic force, and a rotating It is characterized in that a shielding member is provided between the rotary drive section consisting of the driving element.

Note that the shielding member specifically refers to an electromagnetic shielding member,
Either one of heat shielding member or electromagnetic/thermal shielding member
It refers to one thing.

〔Effect of the invention〕

According to the present invention, by taking a very simple measure of simply providing a shielding plate between the rotating anode and the rotating drive unit, it is possible to eliminate factors that inhibit stable support of the rotor, such as electromagnetic waves and radiant heat. can eliminate the direct influence of Therefore, the stable supporting performance of the rotor in the rotary drive unit can be significantly improved.

[Detailed description of the invention]

Hereinafter, details of the present invention will be explained based on illustrated embodiments.

In FIG. 1, l is a cylindrical vacuum container. This vacuum container 1 is composed of divided bodies Ia and lb each having one end open. Both open ends of these divided bodies 1a and 1b are overlapped in the vertical direction in the figure and fixed with screws 2. . An annular shielding plate 3 that divides the internal space of the vacuum container 1 into upper and lower portions in the figure is fixed to this overlapping portion.

This shielding plate 3 is made of, for example, a material with high heat reflectance or
It is formed of a conductive material such as molybdenum or tungsten with a coating material having a high heat reflectance applied to its surface, and functions as an electromagnetic and thermal shield between the upper and lower spaces in the vacuum vessel 10 (FIG. 10).

In the upper space in the figure partitioned by the shielding plate 3 inside the vacuum vessel 1, a cathode 7 and a rotating anode 8 formed, for example, in the shape of a disk are arranged facing each other and separated from each other in the vertical direction in the figure. Teb
Ru.

A filament (not shown) is attached inside the cathode 7. The cathode 7 is connected to a conductor 9.

The conductor 9 has a portion 9a that airtightly penetrates the central portion of the soil wall of the vacuum vessel 1 in the axial direction, and a portion 9a of the vacuum vessel 1 in this portion 9a.
A portion 9 extending, for example at right angles, from the tip located within
b, and the cathode 7 is fixed to the tip of the portion 9b. Note that both ends of the filament are guided to the outside of the vacuum vessel 1 via an insulated wire (not shown) disposed within the conductor 9.

The rotating anode 8 is arranged such that the peripheral part of its upper surface always faces the cathode 7 in the figure, and as the upper surface of the peripheral part approaches the outer periphery, the anode and the like necessary to obtain the desired X-rays are formed on the surface. The rotary anode 8 is provided by a rotary drive mechanism L, which will be described later. is supported by a rotor 11.

On the other hand, a rotor 11 of a rotational drive mechanism is housed in a space at the lower end of the shielding plate 3. That is, in a portion of the wall of the vacuum vessel 1 facing the lower surface of the shielding plate 30 in the figure, there is a recessed wall 15 that is recessed in a cylindrical shape with a bottom toward the shielding plate 3. Furthermore, the recessed wall 15 is formed.
An inner recessed wall 16 is formed in the center of the so-called bottom wall, the center being recessed toward the side opposite to the shielding plate 3, concentrically with the recessed wall 15. The rotor 11 is rotatably housed within the cylindrical space P formed between the recessed wall 15 and the cylindrical wall portion 17 located outside thereof, and within the inner recessed wall 16. .

Broadly speaking, the rotor 11 is disposed coaxially with the rotating anode 8, and its upper end in FIG. An electrically conductive auxiliary shaft 19 is inserted into the cavity surrounded by the inner recessed wall 16 and the upper end in the figure is connected to the auxiliary shaft 19 via the annular insulating material 20, and the lower end in the figure is connected to the auxiliary shaft 19 through the annular insulating material 20. a cylindrical rotor body 2 whose portion is fitted into the cylindrical space P;
It consists of 1. The rotor main body 21 includes a cylindrical body 24 made of a non-magnetic material or a paramagnetic material and having an outer diameter smaller than the inner diameter of the wall portion 17 and a larger inner diameter than the outer diameter of the recessed wall 15; Rings 25a made of a high magnetic permeability material are respectively installed and fixed in annular grooves 24a and 24b formed on the inner circumferential surface of the cylindrical body 24 in two stages vertically in the figure.
, 25b, and a rotor 27 of a motor 26 fixed to, for example, the center of the outer peripheral surface of the cylindrical body 24.

Furthermore, bearings 28a and 28b are provided on the inner surface of the inner recessed wall 16 to mechanically support the auxiliary shaft 19 only in an emergency, etc., without contacting the auxiliary shaft 19 at all times. Furthermore, a pin 29 is provided protruding from the lower end surface of the auxiliary shaft 19 in the drawing.

A contact plate 3o is disposed at a position facing the pin 29, and the contact plate 3θ and the bottle 29 constitute an anode current introducing device. The contact plate 30 is connected to the tip of a conductive rod 3 that passes through the so-called bottom wall of the inner recessed wall 16 in an airtight manner.

A yoke 35 is inserted in a space surrounded by the recessed wall 15 and concentrically with the recessed wall 15. The yoke 35 is constructed, for example, by combining a plurality of blocks and is formed into an annular shape as a whole, and has a hole 36 in the center into which the inner recessed wall 16 can fit. On the outer circumferential surface of the yoke 35, at the upper and lower ends in the figure, there are 9
Four magnetic poles 37*, 37b protruding at an opening angle of 0°,
Two sets of magnetic pole groups 3 for radial position control, one set being 37c and 37d (37b and 3rd are not shown)
B...? 9 is provided. In addition, each magnetic pole group J
The distance between the magnetic poles of the magnetic poles 8 and 39 protruding on the same line perpendicular to the axial center line and the pole face is set to a value approximately equal to the inner diameter of the recessed wall 15. And each magnetic pole group 38°390
A radial stabilizing coil 4 is provided on the outer periphery of each magnetic pole.
,0 are attached. Further, an annular magnetic pole 45 for controlling the axial position is protruded from the shaft center line opening at the center position between each magnetic pole group 38 and 39, and on both sides of the magnetic pole 45 in the axial direction, Axial stabilizing coils 46a and 46b are mounted to sandwich the magnetic poles 45 between them. A ring-shaped permanent magnet 47a247b magnetized in the radial direction is mounted on the outer periphery of the yoke 35 and in a portion located between the magnetic pole group 38 and the coil 461L and between the magnetic pole group 39 and the coil 46b. ing. And as above, coils 40, 46h, 46b, permanent magnet 47
a.

The yoke 35 to which the yoke 47b is mounted is mounted in a space surrounded by the recessed wall 15.

On the outside of the wall portion 17 of the vacuum container 1, a cylindrical body 48 is formed of a non-magnetic material or a paramagnetic material and has a bottomed cylindrical shape with a predetermined gap Qt between the wall portion 17 and the wall portion 17. is installed. At the upper and lower parts of the figure within the above-mentioned interval ffQ, at positions facing the magnetic pole faces of the respective magnetic poles of the magnetic pole group 38, 39, there are displacements for detecting displacement in a direction orthogonal to the axial direction of the rotor main body 21. A detector 50 and a displacement detector 51 for detecting axial displacement are provided, and the gap Q
A stator 52 of the motor 26 is attached at a position facing the rotor 22 inside. The armature winding 53 of the stator 52 is connected to a motor drive power source (not shown), and the output end of each displacement detector 50 and 51 is connected to a rotor stabilization control device (not shown). The rotor stabilization control device described above actually consists of one for stabilizing the rotor in the radial direction and one for stabilizing the rotor in the axial direction. Note that 54 in FIG. 1 indicates an X-ray transmission window.

In the X-ray tube device configured as described above, the magnetic flux generated by the permanent magnets 47a and 47b is transmitted to the permanent magnet 47*.
, 47b to each ringle of the rotor 11 to each magnetic pole to the yoke to the permanent magnets 47a and 47b to form a plurality of magnetic loops. Each of these magnetic loops applies a magnetic force to the rotor 11 in a direction that pinches each magnetic loop.

Due to this magnetic force, the rotor 1 is supported in a completely non-contact state. At this time, the rotor 11 generated by the outside etc.
The axial and radial displacement of each displacement detector 50.5
Detected by 1. Based on this detection signal, the coils wound around each magnetic pole are appropriately energized, and the displacement of the rotor 1 is corrected. Thus, stable non-contact support of the rotor 11 is realized here. Rotor 11zB-e-p26
The rotating anode 8 also rotates.

Therefore, during X-ray irradiation, the rotor II is moved downward in the figure to connect the bottle 29 fixed to the auxiliary shaft 19 and the contact plate 3o.
and a high voltage is applied to the rotating anode 8. As a result, electrons are emitted from the filament of the cathode 7, accelerated, and collide with the rotating anode 8. As a result, the rotating anode 8
X-rays are emitted from the Most of these X-rays are
Although the radiation passes through the ray transmission window 54 and is irradiated to the outside, a portion of the radiation is normally diffused into the interior of the vacuum container 1 .

However, with the configuration of this embodiment, since the conductive shielding plate 3 is provided between the rotating anode and the rotational drive mechanism 10, this shielding plate 3 can sufficiently absorb the above-mentioned diffused X-rays. be able to.

Therefore, the X-rays do not diffuse to the rotational drive mechanism 10K.

Further, as the rotating anode 8 is irradiated with X-rays, the temperature of the rotating anode 8 increases to several hundred degrees. However, in this embodiment, the shielding plate 3 provided between the rotary anode 8 and the rotary drive mechanism 10 has a high heat reflectance, so that the shielding plate 3 exhibits a function of blocking radiant heat.

Therefore, it is possible to effectively prevent the rotational drive mechanism from increasing in temperature due to radiant heat.

In this way, according to this embodiment, the aforementioned effects can be fully achieved.

Note that the present invention is not limited to the embodiments described above. For example, as shown in FIG.
A bearing 28g that mechanically supports the auxiliary shaft 19 only in an emergency may be fixed to the inner circumference of the shaft. If the structure is such that the shielding plate 6° also serves as a support member for the bearing 28a, the absolute position of the bearing 28a and the bearing 28b can be moved upward in the figure without changing the relative positions of the bearing 28a and the bearing 28b. can. Therefore, the space formed by the inner recessed wall 15 of the vacuum container 1 can be downsized, and the increased surplus space can be effectively utilized.

Therefore, as shown in FIG. 2, the outer diameter of the yoke 35 can be reduced to reduce the overall size.

Further, as shown in FIG. 3, a refrigerant passage 7 may be formed inside the shielding plate 70 to effectively release the heat of the shielding plate 2θ to the outside. In this case, as shown in FIG. 3, for example, an annular space R is formed inside the shielding plate 70. Furthermore, the annular space R is divided in the axial direction to form spaces R1°R2, and these spaces R1rR2 are communicated at the inner circumference of the annular space R.
Insert K annular plate 7.

The refrigerant introduction lower 2 and the refrigerant discharge lower 3 may be provided at radially opposite positions on the outer circumference of the shielding plate 70, respectively.

In this case, if a member with high heat absorption and heat conductivity is used for the shielding plate 70, the temperature in the vicinity of the rotating anode can be lowered overall. By flowing a refrigerant (not shown) through the refrigerant passage 71, the heat absorption performance can be further improved, and the effects of the present invention can be further enhanced.

In the above embodiments, a member that satisfies the electromagnetic shielding effect and the thermal shielding effect at the same time is used for the shielding plate, but it is also possible to use a member that can satisfy either of the effects independently. It goes without saying that even if there is, the effects of the present invention can be achieved.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of an X-ray tube device according to one embodiment of the present invention, FIG. 2 is a longitudinal cross-sectional view of an X-ray tube device according to another embodiment of the present invention, and FIG. FIG. 7 is a longitudinal sectional view showing a part of an X-ray tube device according to another embodiment. 1... Vacuum container, 3,60.70... Shielding plate, 7.
... Cathode, 8... Rotating anode, 9... Conductor, 10...
- Rotation drive mechanism, 11... rotor, 19... auxiliary shaft, 25a. 25 b-...Ring, 26...Motor, 28m,
2Elb... Bearing, 29... Pin, 30... Contact plate, 31... Conductive rod, 35-... Yoke, 37 a
*37 b r 37 c t45-...magnetic pole, 40
...Radial stabilization coil, 46m, 46b...
Axial stabilization coil, 47a. 47b... Permanent magnet, 50.51... Displacement detector,
54...X-ray transparent window. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2

Claims (6)

[Claims] (1) It has a cathode, a rotating anode that emits X-rays when electrons emitted from the cathode collide with each other, and a rotor that supports the rotating anode, and the rotor is supported by magnetic force in a completely non-contact manner. What is claimed is: 1. An X-ray tube device comprising an element and a rotational drive section including a rotationally driven element, characterized in that a shielding member is provided between the rotary anode and the rotation drive section. (2) The X-ray tube device according to claim 1, wherein the shielding member is made of a conductive material. (3) The shielding member is made of a material having a high heat absorption rate or a high heat conductivity. X of
wire tube device. (4) The shielding member is made of a material having a high heat reflectance or a material coated with a conniting agent having a high heat reflectance. The X-ray tube device according to any one of the above items. (5) The X-ray tube device according to any one of claims 1 to 3, wherein the shielding member has a refrigerant passage formed therein. (6) The shielding member also serves as a support member for a mechanical bearing that mechanically supports the rotor in an emergency. The X-ray tube device according to item 1.