JP2023119901A - Electron gun, x-ray tube, and manufacturing method for electron gun - Google Patents

Abstract

To provide an electron gun that can prevent a filament from moving with respect to a focusing electrode, an X-ray tube, and a manufacturing method for the electron gun.SOLUTION: The electron gun includes a filament that emits electrons, a filament terminal that extends in an extension direction and is connected to the filament, an insulator having a through-hole that penetrates in the extension direction and where the filament terminal is located, and a focusing electrode that accommodates the filament, the filament terminal, and the insulator. The filament terminal is in contact with the through-hole and fixed to the insulator.SELECTED DRAWING: Figure 3

Description

Embodiments of the present invention relate to electron guns, x-ray tubes, and methods of manufacturing electron guns.

An X-ray tube includes an envelope whose interior is kept in a vacuum, a cathode electron gun that emits electrons, and an anode target that emits X-rays when the emitted electrons collide with each other. A cathode electron gun includes a filament, a filament terminal, an insulator, and a focusing electrode. It is known to connect the filament terminal and the insulator via a metal sleeve.

JP-A-63-105427

The present embodiments provide an electron gun, an X-ray tube, and a method of manufacturing an electron gun that can prevent the filament from moving relative to the focusing electrode.

An electron gun according to one embodiment includes a filament that emits electrons, a filament terminal that extends in an extending direction and is connected to the filament, and a through hole that penetrates in the extending direction and in which the filament terminal is positioned. and a focusing electrode accommodating the filament, the filament terminal, and the insulator, the filament terminal being in contact with the through hole and fixed to the insulator.

An X-ray tube according to one embodiment includes an anode target, a filament that emits electrons, a filament terminal that extends in an extending direction and is connected to the filament, and a filament terminal that penetrates in the extending direction and is positioned at the filament terminal. a cathode electron gun comprising: an insulator having a through hole through which the filament, the filament terminal, and the insulator are accommodated; and an envelope, wherein the filament terminal is in contact with the through hole and fixed to the insulator.

A method for manufacturing an electron gun according to one embodiment includes a filament emitting electrons, a filament terminal extending in an extending direction, an insulator having a through hole penetrating in the extending direction, and a focusing electrode. are prepared, the filament and the filament terminal are connected, the insulator is fixed to the focusing electrode, and the filament terminal is fixed to the insulator by an interference fit.

FIG. 1 is a cross-sectional view showing an example of an X-ray tube according to one embodiment. FIG. 2 is a front view of the cathode electron gun as viewed from arrow A in FIG. FIG. 3 is a cross-sectional view of the cathode electron gun along line BB of FIG. FIG. 4 is a rear view of the cathode electron gun as seen from arrow C in FIG. FIG. 5A is a cross-sectional view showing the manufacturing state of the cathode electron gun according to this embodiment, and shows the state before the filament terminal is fixed to the insulator. FIG. 5B is a cross-sectional view showing a state after adjusting the position of the filament of the cathode electron gun according to this embodiment. FIG. 6 is a rear view showing part of a cathode electron gun according to a modification of this embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. It should be noted that the disclosure is merely an example, and those that a person skilled in the art can easily conceive of appropriate modifications while maintaining the spirit of the invention are, of course, included in the scope of the present invention. In addition, in order to clarify the drawings and descriptions, the width, thickness, shape, etc. of each part may be schematically represented compared to the actual mode, but this is only an example, and the interpretation of the present invention is not intended. It is not limited. In addition, in this specification and each figure, the same reference numerals may be given to the same elements as those described above with respect to the existing figures, and detailed description thereof may be omitted as appropriate.

First, the basic concept of the embodiments of the present invention will be described.
The X-ray tube has an anode target, a cathode electron gun, and an envelope. A cathode electron gun includes a filament, a filament terminal, an insulator, and a focusing electrode. In conventional cathode electron guns, the filament terminal is fixed to the insulator via a metal sleeve. The filament terminal and sleeve are fixed by welding. On the one hand, there is a gap between the filament terminal and the sleeve. As a result, the filament terminal is tilted by the gap with the welded portion as the fulcrum, and the position of the filament moves with respect to the focusing electrode, which may change the focal shape of the X-rays. Furthermore, the filament may come into contact with the focusing electrode.

Therefore, in the embodiments of the present invention, it is possible to improve such a problem and obtain an electron gun, an X-ray tube, and a method of manufacturing an electron gun that can prevent the filament from moving with respect to the focusing electrode. It is a thing. Means and methods for improving the above problems will be described.

FIG. 1 is a cross-sectional view showing an example of an X-ray tube according to one embodiment.
As shown in FIG. 1, the X-ray tube 1 includes an envelope 10, an anode target 21, and a cathode electron gun 31. As shown in FIG. The envelope 10 is made of glass. The envelope 10 accommodates an anode target 21 and a cathode electron gun 31 inside which is maintained in a vacuum state.

Anode target 21 is part of anode 20 . The anode 20 has an anode target 21 and a rotating mechanism 23 . Anode target 21 is formed in a disc shape. The anode target 21 emits X-rays when electrons (electron beams) collide with its surface. Anode target 21 is supported by rotating mechanism 23 . The anode target 21 rotates as the rotation mechanism 23 rotates. The anode target 21 is composed of a target layer that emits X-rays and a target body that supports the target layer. The target layer is made of tungsten, for example. The target body is made of metal such as molybdenum alloy, for example. A stator coil (not shown) is installed outside the envelope 10 . The stator coil generates a magnetic field by being supplied with a current from a power source (not shown), and drives the rotating mechanism 23 with the generated magnetic field.

Cathode electron gun 31 is part of cathode 30 . The cathode 30 has a cathode electron gun 31 and a support portion 33 . The cathode electron gun 31 faces the anode target 21 inside the envelope 10 . The cathode electron gun 31 emits electrons toward the anode target 21 when a high voltage is applied. The cathode electron gun 31 is also simply called an electron gun. The support portion 33 has a cavity through which a wiring 35 connecting the cathode electron gun 31 and a power source (not shown) passes.

FIG. 2 is a front view of the cathode electron gun 31 as viewed from arrow A in FIG.
As shown in FIG. 2, the cathode electron gun 31 includes a focusing electrode 310 and an electron emission source 321 that emits electrons. In this embodiment, the cathode electron gun 31 has one electron emission source 321 . The cathode electron gun 31 can have a plurality of electron emission sources 321, and may have two electron emission sources 321, for example.

Focusing electrode 310 controls electrons emitted from electron emission source 321 . For example, the focusing electrode 310 focuses electrons emitted from the electron emission source 321 to a focal point on the anode target 21 by being supplied with a current. A groove portion 331 is formed in the first surface 311 of the focusing electrode 310 . The electron emission source 321 is housed in the groove portion 331 . Electron emission source 321 emits electrons toward anode target 21 . When the cathode electron gun 31 has a plurality of electron emission sources 321 , the focusing electrode 310 has the same number of grooves 331 as the electron emission sources 321 .

FIG. 3 is a cross-sectional view of cathode electron gun 31 along line BB in FIG.
As shown in FIG. 3, the cathode electron gun 31 comprises a focusing electrode 310, an electron emission source 321, and insulators 51,52.
The focusing electrode 310 is formed with a groove portion 331 , a pair of first receiving holes 11 and 12 and a pair of second receiving holes 13 and 14 . The first receiving hole 11 and the first receiving hole 12 are positioned apart. The first accommodation hole 11 penetrates from the groove portion 331 to the second accommodation hole 13 . The first receiving hole 12 penetrates from the groove portion 331 to the second receiving hole 14 . The second receiving hole 13 penetrates from the first receiving hole 11 to the second surface 312 located on the opposite side of the first surface 311 . The second receiving hole 14 penetrates from the first receiving hole 11 to the second surface 312 of the focusing electrode 310 . The inner diameter of the second receiving hole 13 is larger than the inner diameter of the first receiving hole 11 . The inner diameter of the second receiving hole 14 is larger than the inner diameter of the first receiving hole 12 .

The insulators 51 and 52 are fixed in the second receiving holes 13 and 14 respectively by a method such as caulking or brazing. The insulators 51 and 52 are made of an electrically insulating material, such as ceramic such as steatite. The insulator 51 and the insulator 52 respectively have a through hole 51A and a through hole 52A penetrating in the extension direction X described later.

The electron emission source 321 has a filament FL and a pair of filament terminals 41 and 42 . The filament FL has a coil portion C1 and leg portions LG1 and LG2 extending from the coil portion C1. The filament FL is made of, for example, tungsten or an alloy containing tungsten as a main component. The coil portion C1 is heated by being supplied with an electric current and emits electrons. The filament terminal 41 and the filament terminal 42 are each connected to the filament FL, extend in the extension direction X from the connection portion with the filament FL, and have a rod-like shape. The filament terminal 41 and the filament terminal 42 are connected to a wiring 35 connected to a power supply (not shown), and conduct current supplied from the power supply to the coil portion C1 of the filament FL. The filament terminal 41 and the filament terminal 42 are made of iron, an alloy containing iron as a main component, molybdenum, or an alloy containing molybdenum as a main component.

The filament terminal 41 is fixed to the insulator 51 in contact with the through hole 51A. The filament terminal 42 is fixed to the insulator 52 in contact with the through hole 52A. The filament terminal 41 and the filament terminal 42 are electrically insulated from the focusing electrode 310 by insulators 51 and 52, respectively. That is, the electron emission source 321 is electrically insulated from the focusing electrode 310 .

FIG. 4 is a rear view of the cathode electron gun 31 as seen from arrow C in FIG. In FIG. 4, a focusing electrode 310, insulators 51 and 52, and filament terminals 41 and 42 are shown. As shown in FIG. 4, the outer circumference of the filament terminal 41 and the outer circumference of the filament terminal 42 are circular. However, the shape of the outer periphery is not limited to a circular shape, and may be formed into a shape having corners, for example, a regular octagon. The inner periphery of the through hole 51A of the insulator 51 and the inner periphery of the through hole 52A of the insulator 52 are circular. However, the shape of the inner periphery is not limited to a circular shape, and may be formed into a shape having corners, for example, a regular octagon. The filament terminal 41 is fixed to the through hole 51A of the insulator 51 by interference fit. The filament terminal 42 is fixed to the through hole 52A of the insulator 52 by interference fit. For example, when the inner diameter of the through hole 51A of the insulator 51 is 2 mm, the interference between the filament terminal 41 and the insulator 51 is set to 0.005 mm.

Next, a method for manufacturing the cathode electron gun 31 according to this embodiment will be described.
FIG. 5A is a sectional view showing the manufacturing state of the cathode electron gun 31 according to this embodiment, and shows the state before the filament terminals 41 and 42 are fixed to the insulators 51 and 52. FIG. FIG. 5B is a cross-sectional view showing a state after adjusting the position of the filament FL of the cathode electron gun 31 according to this embodiment. As shown in FIGS. 5A and 5B, when the manufacturing of the cathode electron gun 31 is started, first, the filament FL, the filament terminals 41 and 42, the insulators 51 and 52, the focusing electrode 310, and the base 60 are assembled. , block 70 and heater 80 are provided.

Next, as shown in FIG. 5A, the filament FL and filament terminals 41 and 42 are connected. Specifically, the leg portion LG1 of the filament FL and the filament terminal 41 are connected, and the leg portion LG2 of the filament FL and the filament terminal 42 are connected. Meanwhile, the insulator 51 and the insulator 52 are fixed to the focusing electrode 310 . Specifically, the insulator 51 is fixed in the second accommodation hole 13 of the focusing electrode 310 , and the insulator 52 is fixed in the second accommodation hole 14 of the focusing electrode 310 . A method for fixing the insulator 51 and the insulator 52 to the focusing electrode 310 is caulking or brazing.

Subsequently, the filament terminals 41 and 42 are fixed to the insulators 51 and 52, respectively, by shrink fitting. Specifically, first, the insulator 51 and the insulator 52 are heated using the heater 80 arranged outside the focusing electrode 310, and the inner diameter D51 of the insulator 51 and the inner diameter D52 of the insulator 52 are expanded by thermal expansion. Let The heating temperature is, for example, about 500.degree. As a result, the inner diameter D51 becomes larger than the outer diameter D41 of the filament terminal 41 and the inner diameter D52 becomes larger than the outer diameter D42 of the filament terminal 42 . At room temperature before assembly, the inner diameter D51 is smaller than the outer diameter D41, and the inner diameter D52 is smaller than the outer diameter D42.

After the insulators 51 and 52 reach a predetermined temperature by heating, the filament terminals 41 and 42 are moved in the extending direction X to insert the filament terminal 41 into the through hole 51A of the insulator 51, The filament terminal 42 is inserted into the through hole 52A of the insulator 52 . At this time, the filament terminals 41 and 42 are inserted from the groove 331 of the focusing electrode 310 . That is, the filament terminal 41 and the filament terminal 42 first pass through the groove 331, then through the first receiving holes 11 and 12, and finally through the through holes 51A and 52A of the insulators 51 and 52, respectively. In FIG. 5A, the extension direction X, which is the direction in which the filament terminals 41 and 42 move, and the gravitational direction G are shown to match, but the present invention is not limited to the alignment. The direction X and the gravitational direction G may be orthogonal. Instead of the filament terminals 41 and 42, the focusing electrode 310 may be moved to insert the filament terminals 41 and 42 into the through holes 51A and 52A.

On the other hand, a block 70 is installed on the horizontal surface 61 of the base 60 . Specifically, the block 70 is placed on the horizontal surface 61 so that the reference surface 71 is located on the opposite side of the base 60 . At this time, the block 70 and the base 60 are positioned in this order in the direction of gravity G. As shown in FIG. After installing the block 70 on the base 60 and inserting the filament terminals 41 and 42 into the through holes 51A and 52B, the focusing electrode 310 accommodating the insulators 51 and 52, the filament FL, and the filament terminals 41 and 42 is assembled. is placed on the base 60. At this time, the focusing electrode 310 is installed on the base 60 so that the block 70 is positioned in the groove 331 of the focusing electrode 310 . Until the focusing electrode 310 is installed on the base 60, it is necessary to support the electron emitting source 321 in order to prevent the electron emitting source 321 from falling from the focusing electrode 310 in the direction of gravity G. . As a method for supporting the electron emission source 321, for example, there is a method in which a wire (not shown) is fixed to the ends of the filament terminals 41 and 42 to which the filament FL is not connected and suspended.
After the focusing electrode 310 is installed on the base 60, the position of the filament FL is adjusted by moving the filament terminal 41 and the filament terminal 42 so that the coil portion C1 of the filament FL is in contact with the reference surface 71 of the block 70. . After the position of the filament FL is determined, the insulators 51 and 52 are cooled. Thereby, the filament terminals 41 and 42 are fixed to the insulators 51 and 52 . The insulator may or may not be heated by the heater 80 during the position adjustment of the filament FL. In the case where the heater 80 is used for heating, once the position of the filament FL is determined, the heating by the heater 80 is stopped and the insulators 51 and 52 are cooled.

In the manufacturing method described above, the filament terminals 41 and 42 are fixed to the insulators 51 and 52 by shrink fitting. Alternatively, the filament terminals 41 and 42 may be fixed to the insulators 51 and 52 by cold fitting or press fitting. The interference fitting method for fixing the filament terminals 41 and 42 to the insulators 51 and 52 by cold fitting and for fixing the filament terminals 41 and 42 to the insulators 51 and 52 by press fitting will be described below.

In the case of cold fitting, the filament FL and the filament terminals 41 and 42 are connected, the insulator 51 and the insulator 52 are fixed to the focusing electrode 310, and then the filament terminals 41 and 42 are cooled. The cooling of the filament terminals 41 and 42 can be performed using, for example, liquid nitrogen or dry ice. After the filament terminals 41 and 42 reach a predetermined temperature by cooling, the filament terminal 41 is inserted into the through-hole 51A of the insulator 51 and the filament terminal 42 is inserted into the through-hole 52A of the insulator 52 .

In the case of press-fitting, after connecting the filament FL and the filament terminals 41 and 42 and fixing the insulator 51 and the insulator 52 to the focusing electrode 310, a load of a predetermined size or more in the extending direction X is applied to the filament terminal 41. , 42 and the insulators 51 and 52 , the filament terminal 41 is inserted into the through hole 51 A of the insulator 51 and the filament terminal 42 is inserted into the through hole 52 A of the insulator 52 .
In addition, the heating of the insulators 51 and 52 described in the manufacturing method by shrink fitting and the cooling of the filament terminals 41 and 42 described in the manufacturing method by cooling fitting are combined, and the filament terminals 41 and 42 are connected by interference fitting. It may be fixed to the insulators 51 and 52 .

According to the electron gun, the X-ray tube, and the method of manufacturing the electron gun according to the present embodiment configured as described above, the electron gun includes the filament FL, the filament terminals 41 and 42, and the insulators 51 and 52. , and a focusing electrode 310 . The filament terminal 41 and the filament terminal 42 are in contact with the through holes 51A and 52A, respectively, and fixed to the insulators 51 and 52 .

The X-ray tube has an anode target 21 and an envelope 10 in addition to the electron gun.
The method of manufacturing the electron gun also includes a method of fixing the filament terminals 41 and 42 to the insulators 51 and 52, respectively, by interference fitting. The method of interference fitting includes shrink fitting, cooling fitting, press fitting, and the like. Accordingly, it is possible to obtain an electron gun, an X-ray tube, and a method of manufacturing an electron gun that can prevent the filament FL from moving with respect to the focusing electrode 310 .

(Modification)
A modification of the above embodiment will be described. However, the cathode electron gun has the same structure as that of the above embodiment except for the structure described in the modified example.
FIG. 6 is a rear view showing a part of the cathode electron gun 31 according to a modification of this embodiment. In FIG. 6, the filament terminal 41, the insulator 51, and the focusing electrode 310 are shown. Although the filament terminal 41 and the insulator 51 will be described below as an example, the filament terminal 42 and the insulator 52 also have the same configuration.

As shown in FIG. 6, the focusing electrode 310 accommodates the filament terminal 41 and the insulator 51 in the second accommodation hole 13 . The insulator 51 surrounding the filament terminal 41 is composed of a first insulator 51B and a second insulator 51C. The shape of the outer periphery of the first insulator 51B and the shape of the outer periphery of the second insulator 51C are shapes obtained by dividing an annular ring. In this modification, the insulator 51 is composed of two insulators, the first insulator 51B and the second insulator 51C, but may be composed of three or more insulators. The insulator 51 is fixed to the focusing electrode 310 by caulking.

The filament terminal 41 is in contact with the first insulator 51B and the second insulator 51C and fixed to the first insulator 51B and the second insulator 51C. The filament terminal 41 is fixed to the first insulator 51B and the second insulator 51C by fixing the first insulator 51B and the second insulator 51C to the focusing electrode 310 by caulking. Specifically, by striking the second surface 312 of the focusing electrode 310, projections 313 and 314 are formed. The body 51C contacts the filament terminal 41, and the filament terminal 41 is fixed to the first insulator 51B and the second insulator 51C. In this modified example, the case where two projections 313 and 314 are formed has been described, but one projection or three or more projections may be formed.

According to the electron gun and the X-ray tube according to the modified example of this embodiment configured as described above, the electron gun includes the filament FL, the filament terminals 41 and 42, the insulators 51 and 52, and the focusing electrode 310. and The insulators 51 and 52 are composed of a plurality of insulators. By fixing the insulators 51 and 52 to the focusing electrode 310, the filament terminals 41 and 42 are fixed to the insulators 51 and 52, respectively. This makes it possible to obtain an electron gun and an X-ray tube that are easy to assemble, in addition to the same effects as in the above embodiment.

While embodiments of the invention have been described, the embodiments are provided by way of example and are not intended to limit the scope of the invention. The novel embodiments described above can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. The above-described embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.
In the above embodiments, a rotating anode X-ray tube was described as an example, but the present invention is applicable to an X-ray tube having an envelope, an anode target, and a cathode electron gun, and a fixed anode X-ray tube. Applicable in all X-ray tubes including

Reference Signs List 1 X-ray tube 10 Envelope 11, 12 First receiving hole 13, 14 Second receiving hole 20 Anode 21 Anode target 23 Rotation mechanism 30 Cathode 31 Cathode electron gun 33 Support portion 41, 42 Filament terminal 51, 52 Insulator 51A, 52A Through hole 51B First insulator 51C Second insulator 80 Heater 310 Focusing electrode 331 Groove portion FL Filament X Extending direction

Claims (6)

a filament that emits electrons;
a filament terminal extending in the extending direction and connected to the filament;
an insulator having a through hole penetrating in the extension direction and in which the filament terminal is positioned;
a focusing electrode that accommodates the filament, the filament terminal, and the insulator;
The filament terminal is in contact with the through hole and fixed to the insulator,
electron gun. an anode target;
a filament that emits electrons; a filament terminal that extends in an extending direction and is connected to the filament; an insulator that has a through hole that penetrates in the extending direction and in which the filament terminal is positioned; and a focusing electrode housing the filament terminal and the insulator;
an envelope containing the anode target and the cathode electron gun,
The filament terminal is in contact with the through hole and fixed to the insulator,
X-ray tube. preparing a filament that emits electrons, a filament terminal that extends in an extending direction, an insulator that has a through hole penetrating in the extending direction, and a focusing electrode;
connecting the filament and the filament terminal;
fixing the insulator to the focusing electrode;
securing the filament terminal to the insulator with an interference fit;
A method of manufacturing an electron gun. The method of interference fit is a shrink fit that heats the insulator.
4. A method of manufacturing an electron gun according to claim 3. The interference fit method is a cold fit that cools the filament terminal.
4. A method of manufacturing an electron gun according to claim 3. The interference fitting method is press fitting in which a load of a predetermined size or more in the extending direction is applied to the filament terminal and the insulator.
4. A method of manufacturing an electron gun according to claim 3.

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