JPH0765758A - Filament assembly for x-ray generating device - Google Patents

Abstract

PURPOSE:To obtain a narrow width filament assembly allowing easy assembly in the filament assembly built in an X-ray generating device. CONSTITUTION:In a filament assembly 11 for an X-ray generating device having a pair of stems 3 supported by an insulator 12, a filament 7 stretched between the stems 3, a holder 13 for holding the filament 7, and a board 15 for securing the holder 13 to the insulator 12, the board 15 is secured to the insulator 12, using brazing. Thus, unlike a conventional method, fixing the board 15 to the insulator 12 with screws, the board 15 is fixed to the insulator 12, using brazing to reduce the width of the filament assembly 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray generator for causing an electron to collide with a target to generate an X-ray, and more particularly to a filament assembly mainly including a filament for emitting an electron.

[0002]

2. Description of the Related Art An X-ray diffractometer or other various X
An X-ray generator for generating X-rays is indispensable for equipment utilizing rays. This X-ray generator generally has a filament that emits electrons when energized, and a target that is arranged so as to face the filament. A vacuum is maintained around the filament and target. The electrons emitted from the filament collide with the target at high speed, and X-rays are emitted from the colliding portion.

Conventionally, filaments are handled in the form of a filament assembly as shown in FIG. The filament assembly 1 is fixed to the back surface of the insulator 2 by an insulator 2 formed of alumina (Al ₂ O ₃ ) or the like, a pair of stems 3 and 3 vertically penetrating the insulator 2, and screws 4 and 4. And a seat plate 5 that is formed. Each stem 3 has a terminal 6 fixed to its lower end, while a filament 7 is connected to its upper end. The filament assembly 1 is configured such that screws are passed through the two through holes 8 provided in the seat plate 5 and the screws are fixed to a predetermined mounting place using the screws.

[0004]

However, the above-mentioned conventional filament assembly has the following drawbacks. That is, since the two screws 4 are used to fix the insulator 2 to the seat plate 5, the width W of the filament assembly 1 cannot be reduced. Also, a troublesome process for screwing is required.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a filament assembly having a narrow width and easy to assemble.

[0006]

In order to achieve the above object, a filament assembly of an X-ray generator according to the present invention is provided with a pair of stems supported by an insulator and stretched between the stems. In a filament assembly of an X-ray generator having a filament, a holder for holding the filament, and a seat plate for fixing the insulator to the holder, the seat plate is fixed to the insulator by brazing. .

As the brazing material for the above brazing,
For example, titanium low can be used.

[0008]

By fixing the seat plate to the insulator by brazing, the area for screwing is unnecessary, and the width of the filament assembly can be narrowed accordingly. Usually, the filament assembly is incorporated in a holder having, for example, a rectangular parallelepiped shape, and the holder is further incorporated in the tube wall of the X-ray tube. In this assembled state, electrons are emitted from the filament and X-rays are emitted from the target,
The X-rays are extracted outside the X-ray tube wall. by the way,
If the distance between the holder and the X-ray tube wall is small, electric discharge may occur between the holder and the X-ray tube wall, which may damage the target or the like. However, according to the present invention, since the width of the filament assembly can be made small, the width of the holder for storing the filament assembly can be made small, and therefore the distance between the filament assembly and the wall of the X-ray tube can be made large, which can prevent the occurrence of discharge. It can be surely suppressed.
Also, by reducing the width of the X-ray tube, the overall shape of the X-ray tube can be made smaller.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 shows the entire X-ray generator equipped with the filament assembly according to the present invention. This X-ray generator has an electron gun 9 and a target 10. The electron gun 9 has a holder 13 having a substantially rectangular parallelepiped shape, and the filament assembly 11 and the Wehnelt 14 are stored in the holder 13. A rectangular opening or slit 20 for exposing the filament to the outside is formed at approximately the center of the Wehnelt 14.

As shown in FIG. 1, the filament assembly 11 is a rectangular parallelepiped insulator 12 formed of alumina (Al ₂ O ₃ ) or the like, a pair of stems 3 vertically penetrating the insulator 12, and an insulator. 12 has a rectangular seat plate 15 fixed to the back surface by brazing. Seat 15
Is formed of, for example, stainless steel. Each stem 3
The electrode terminals 6 are fixed to their lower ends by brazing, and the filaments 7 are connected to their upper ends. The filament 7 is exposed to the outside through the slit 20 formed in the Wehnelt 14 in FIG. Returning to FIG. 1, a large-diameter counterbore through hole 16 is formed at a substantially central position of the insulator 12, and a small-diameter screw through hole is provided at a substantially central position of the seat plate 15 at a position corresponding to the through hole 16. The hole 17 is opened.

When the holder 13 is viewed from the direction of arrow A in FIG. 2, it has a shape as shown in FIG. As shown in the figure, the holder 13 includes a circular recess 18 and a rectangular recess 19 continuous with the recess 18. A circular through hole 30 for fitting the Wehnelt 14 is formed in the circular recess 18, and a screw hole 21 is formed in the rectangular recess 19. As shown in FIG. 4, the through hole 30 of the circular recess 18 is formed.
A circular Wehnelt 14 is fitted inside and fixed by screws or the like, and the filament assembly 11 is stored in the rectangular recess 19. The filament assembly 11 is fixed to the holder 13 by a screw 22 that penetrates the counterbore through hole 16 (FIG. 1) and the screw through hole 17 (FIG. 1) and is screwed into the screw hole 17 (FIG. 1). In this mounted state, the filament 7 is exposed to the outside through the slit 20 formed in the Wehnelt 14.

When the filament assembly 11 is assembled to the holder 13, the upper end surface 15a (FIG. 1) and the left side surface 15b of the seat plate 15 are respectively attached to the upper abutment portion 19a and the side abutment portion 19b of the rectangular recess 19. The filaments 7 are abutted against each other, whereby the position of the filament 7 with respect to the holder 13 is fixed.

Returning to FIG. 2, the tube current power supply 23 is connected between both electrode terminals 6, and one electrode terminal 6 and the target 1 are connected.
A tube voltage power supply 24 is connected between the electrodes 0 and 0, and a bias power supply 25 is connected between the one electrode terminal 6 and the Wehnelt 14. As shown in FIG. 5, the holder 13 and the target 10 are hermetically sealed by an X-ray tube wall 26, and the inside of the X-ray tube wall 26 is exhausted by a turbo molecular pump 27 fixedly installed on the X-ray tube wall 26. And maintained in vacuum. In FIG. 2, the filament current 7 is energized through the electrode terminal 6 by the function of the tube current power source 23, and the energization causes the filament 7 to generate heat and emit electrons. The direction of the emitted electrons is controlled by the bias voltage applied between the Wehnelt 14 and the filament 7 by the operation of the bias power supply 25, and the target 10 is controlled.
It strikes the focus of the above shape. At this time, the voltage applied between the filament 7 and the target 10 by the function of the tube voltage power supply 24, that is, the tube voltage, accelerates the electrons traveling from the filament 7 to the target 10 at high speed.

In this embodiment, as shown in FIG.
5 is fixed to the insulator 12 by brazing. Therefore,
As shown in FIG. 6, the width W can be made very small as compared with the conventional filament assembly in which both are fixed by the screw 4. The fact that the width W of the filament assembly 11 is small means that the width W ′ of the holder 13 can be made small in FIG.
This means that the distance Wa between the and can be widened. By setting the interval Wa to be wide, it is possible to reliably prevent the occurrence of discharge when the target 10 generates X-rays. In other words, even if the X-ray tube 26 is downsized, it is possible to prevent the occurrence of discharge.

Although the present invention has been described with reference to one embodiment, the present invention is not limited to the embodiment and can be variously modified within the technical scope described in the claims.

For example, the insulator 12 and the seat plate 15 may have any shape other than the illustrated shapes.

[0017]

According to the present invention, since the seat plate is fixed to the insulator by brazing, the width of the filament assembly can be made smaller than in the case where the seat plate is fixed by screws. When assembled in a tube, the space between the holder and the X-ray tube wall can be set wide,
Therefore, the occurrence of discharge can be prevented. Further, it is possible to form the X-ray tube in a small size while preventing the occurrence of discharge. Further, the work becomes easier as compared with the case where the screwing is used.

According to the filament assembly of the second aspect, the filament can be accurately and easily positioned at a predetermined position.

According to the filament assembly of the third aspect, the width of the filament assembly can be further reduced.

[0020]

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing an embodiment of a filament assembly of an X-ray generator according to the present invention.

FIG. 2 is a perspective view schematically showing an X-ray generator using the filament assembly.

FIG. 3 is a front view showing the inside of an example of a holder for supporting a filament.

FIG. 4 is a front view showing a state in which a filament assembly is attached to a holder.

FIG. 5: X with filament and holder assembled
It is a front sectional view of a line generator.

FIG. 6 is a perspective view showing a conventional filament assembly.

[Explanation of symbols]

 3 Stem 7 Filament 10 Target 11 Filament Assembly 12 Insulator 13 Holder 14 Wehnelt 15 Seatboard 16 Through Hole for Counterbore 17 Through Hole for Screw 18 Recess for Wehnelt Storage 19 Recess for Filament Assembly 19a Seatboard Abutment 19b Seatboard Butting part

Claims (3)

[Claims] 1. An X having a pair of stems supported by an insulator, a filament stretched between the stems, a holder for holding the filament, and a seat plate for fixing the insulator to the holder. A filament assembly for a wire generator, characterized in that the seat plate is fixed to the insulator by brazing. 2. The positioning abutment portion is provided inside the holder, and the filament is positioned with respect to the holder by bringing the end surface of the seat plate into contact with the abutment portion. A filament assembly of the described X-ray generator. 3. A counterbore through hole provided in a portion of the insulator between a pair of stems, and a counterbore having an outer diameter provided in a portion of the seat plate corresponding to the counterbore through hole. The X-ray generator according to claim 1, further comprising: a through hole for a screw smaller than the through hole for fixing, and fixing the insulator to the holder by using a screw inserted into the through hole. Filament assembly.