JP2017228505A - X-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray tube capable of increasing the surface area of a getter material with respect to an arrangement space of a non-evaporation type getter.SOLUTION: An X-ray tube includes: a cathode emitting a thermion; an anode target emitting X-rays by the collision of electrons emitted from the cathode; and an electrically insulating vacuum envelope receiving the anode target and the cathode and keeping the insulation between the anode target and the cathode. A non-evaporation type getter having a metal plate is provided within the vacuum envelope, the metal plate holding, on a surface thereof, a getter layer (getter material) adsorbing gas molecules. In the non-evaporation type getter, the metal plate is bent into a curved shape together with the getter layer or folded to form an angle.SELECTED DRAWING: Figure 2

Description

  Embodiments of the present invention relate to an x-ray tube.

  In general, an X-ray tube is used for medical or dental use as an X-ray diagnosis. In this type of X-ray tube, a cathode and an anode target are disposed in a vacuum envelope, and X-rays are emitted when electrons emitted from the cathode collide with the anode target.

  A getter is placed in the vacuum envelope, and the getter particles adsorb gas molecules in the vacuum envelope, thereby removing the gas remaining in the vacuum envelope and reducing the degree of vacuum. It is known.

  As this type of getter, there are an evaporable getter and a non-evaporable getter, both of which utilize the exhaust action of the getter particles (getter material) by chemical adsorption of the active metal surface.

The evaporative getter heats a getter material such as BaAL ₄ to form a vapor deposition film in a predetermined region, but requires a space for securing a wide vapor deposition area. On the other hand, a non-evaporable getter is used by heating a getter material such as titanium (Ti) or zirconium (Zr) alloy with a heater built in the getter or by activating the surface by external heating. If it is covered with gas molecules, the gas adsorption capacity decreases.

Japanese Utility Model Publication No. 62-096252 Japanese Utility Model Publication No. 62-0666156

  The above-described evaporation type getter forms a barium vapor deposition film in the X-ray tube and adsorbs gas molecules to the barium vapor deposition film. However, since there is a high possibility that the insulation of the electrical insulator is impaired as the barium evaporates, The area where barium is deposited is limited and generally does not provide sufficient surface area.

  On the other hand, in the non-evaporable getter, after the surface is activated by heating, gas molecules are adsorbed on the surface of the getter. If the temperature of the getter is low, the adsorbed gas molecules are difficult to diffuse into the getter, and the gas adsorption capacity of the getter gradually decreases.

  Due to the circumstances described above, it has been desired to stably maintain a low degree of vacuum in the tube for a long time.

  Embodiments of the present invention provide an X-ray tube that can stably maintain a low in-tube vacuum over a long period of time.

An X-ray tube according to an embodiment is:
A cathode that emits thermal electrons;
An anode target that emits X-rays when electrons emitted from the cathode collide, and an anode having an anode extension connected to the anode target;
An electrically insulating vacuum envelope that houses the anode target and the cathode and maintains insulation between the anode target and the cathode;
A non-evaporable getter having a metal plate provided in the vacuum envelope and having a getter material that adsorbs gas molecules held on the surface thereof,
The non-evaporable getter is formed by bending the metal plate into a curved shape or forming an angle.

Moreover, the X-ray tube which concerns on one Embodiment is
A cathode that emits thermal electrons;
An anode target that emits X-rays when electrons emitted from the cathode collide, and an anode having an anode extension connected to the anode target;
An electrically insulating vacuum envelope that houses the anode target and the cathode and maintains insulation between the anode target and the cathode;
A non-evaporable getter composed of a non-evaporable getter unit, which is provided in the vacuum envelope and has a metal plate on which a getter material that adsorbs gas molecules is held,
In the non-evaporable getter, a plurality of non-evaporable getter units are arranged in series, the ends of the metal plates of the adjacent non-evaporable getter units are connected to each other, and the whole is wound more than once. One end of the metal plate of the non-evaporable getter unit on one end side is disposed on the inner peripheral side of the other end of the metal plate of the non-evaporable getter unit on the other end side.

Moreover, the X-ray tube which concerns on one Embodiment is
A cathode that emits thermal electrons;
An anode target that emits X-rays when electrons emitted from the cathode collide, and an anode having an anode extension connected to the anode target;
An electrically insulating vacuum envelope that houses the anode target and the cathode and maintains insulation between the anode target and the cathode;
A non-evaporable getter composed of a non-evaporable getter unit provided in the vacuum envelope and having a metal plate holding a getter material that adsorbs gas molecules on its surface;
The non-evaporable getter is provided with a plurality of non-evaporable getter units in parallel.

FIG. 1 is a cross-sectional view showing a schematic configuration of the X-ray tube according to the first embodiment. FIG. 2 is a plan view of the non-evaporable getter used in the first embodiment. FIG. 3 is a diagram of a non-evaporable getter before processing of the non-evaporable getter used in the first embodiment, wherein (a) is a plan view and (b) is a front view. FIG. 4 is a plan view of a non-evaporable getter used in the second embodiment. FIG. 5 is a plan view of a non-evaporable getter used in the third embodiment. FIG. 6 is a plan view of a non-evaporable getter used in the fourth embodiment. FIG. 7 is a plan view of a non-evaporable getter used in the fifth embodiment. FIG. 8 is a plan view of a non-evaporable getter used in the sixth embodiment. FIG. 9 is a plan view of a non-evaporable getter used in the seventh embodiment. FIG. 10 is a plan view of a non-evaporable getter used in the eighth embodiment.

  Hereinafter, the X-ray tube according to each embodiment will be described in detail with reference to the drawings. In addition, in each figure, what is shown by a hatch is a getter layer and does not show a cross section. In addition, for the sake of clarity, the drawings may be schematically represented with respect to the width, thickness, shape, etc. of each part as compared to actual aspects, but are merely examples, and The interpretation is not limited. In addition, in the present specification and each drawing, components that perform the same or similar functions as those described above with reference to the previous drawings are denoted by the same reference numerals, and repeated detailed description may be omitted as appropriate. .

(First embodiment)
First, the X-ray tube 1 according to the first embodiment will be described with reference to FIGS.

  As shown in FIG. 1, an X-ray tube 1 is provided with a cathode 3 that emits electrons, a cathode support 9, and an electron 5 that is provided so as to face the cathode 3 and is emitted from the cathode 3. A discharge target anode target 7 a, a non-evaporable getter 11, and an electrically insulating vacuum envelope 13 that keeps insulation between the anode target 7 a and the cathode 3 are provided. The terminals 3 a and 3 b of the cathode 3, the cathode support 9 and the anode extension portion 7 b are extended outside the vacuum envelope 13. The non-evaporable getter 11 is attached between the terminals 3 a and 3 b of the cathode 3. The anode target 7a and the anode extension portion 7b constitute the anode 7.

  As shown in FIG. 2, the non-evaporable getter 11 has a metal plate 15 and a getter layer 17 made of getter material formed on both surfaces of the metal plate 15. The getter layer 17 is formed on the metal plate 15 while leaving one end 15a and the other end 15b in the longitudinal direction as welding allowance or fixing allowance.

  In this embodiment, the other end 15b of the non-evaporable getter 11 is fixed to one terminal 3a of the cathode 3 by welding.

  In the first embodiment, as shown in FIG. 3, the non-evaporable getter 11 is an original non-evaporable getter 11A in which getter layers 17 are formed on both surfaces of a flat metal plate 15, as shown in FIG. It is formed in a spiral shape. In other words, in the present embodiment, the metal plate 15 is formed in a curved shape together with the getter layer 17, and as a whole, the metal plate 15 is wound one or more times to form a spiral shape. In this embodiment, it is wound about three times, and one end 15a of the metal plate 15 is located on the inner peripheral side of the other end 15b.

The metal plate 15 holds the getter layer 17 on the surface. In this embodiment, the getter layer 17 is formed on both surfaces of the metal plate 15.
The metal plate 15 has flexibility and is made of a metal material that can be bent or bent to form an angle, and is made of, for example, stainless steel or titanium alloy.

  The getter layer 17 formed on the metal plate 15 is made of getter material (powder) such as titanium (Ti), zirconium (Zr), or an alloy thereof.

  The non-evaporable getter 11 can be activated (heated) by either external heating (high-frequency heating) or energization heating (heating by heating by passing an electric current).

  Next, the operation and effect of the X-ray tube 1 according to the first embodiment will be described.

  According to the X-ray tube 1 according to the first embodiment, when the non-evaporable getter 11 provided in the vacuum envelope 13 is heated to, for example, 200 ° C. to 400 ° C. by external heating, The surface of the getter material constituting the layer 17 is activated. Thereby, gas molecules such as hydrogen molecules remaining in the vacuum envelope 13 are adsorbed, and the degree of vacuum in the vacuum envelope 13 is lowered.

  In the first embodiment, the non-evaporable getter 11 is formed by bending the metal plate 15 having the getter layer 17 formed on the surface thereof into a curved shape together with the getter layer 17, so that the getter layer 17 is disposed with respect to the arrangement space of the non-evaporable getter 11. Since the surface area can be increased compared to the case where the surface area is flat (see FIG. 3), the X-ray tube 1 increases the gas adsorbing ability with respect to the arrangement space of the non-evaporable getter 11 and is stable in the tube for a long time. The degree of vacuum can be maintained. In particular, in the first embodiment, the non-evaporable getter 11 forms a getter layer 17 over the entire arrangement space of the non-evaporable getter 11 by winding the metal plate 15 together with the getter layer 17 in a spiral shape. Since the density of the material can be increased, the surface area of the getter layer can be 2 to 10 times that of the original non-evaporable getter 11A shown in FIG.

  Other embodiments will be described below. In the embodiments described below, the same reference numerals are given to the portions having the same functions and effects as those of the above-described embodiment, and the detailed description of the portions will be given. In the following description, differences from the embodiment will be mainly described.

(Second Embodiment)
FIG. 4 shows a non-evaporable getter 11 used in the X-ray tube 1 according to the second embodiment. As shown in FIG. 4, the non-evaporable getter 11 used in the second embodiment is formed by folding the flat non-evaporable getter 11A shown in FIG. 3 at an angle at a predetermined interval in the longitudinal direction. Concentric horns are formed.

  Specifically, in the second embodiment, the flat non-evaporable getter 11A (see FIG. 3) is bent at an angle α for each predetermined dimension, and is wound approximately two and a half rounds concentrically. The angle α is substantially a right angle (90 degrees) in the second embodiment, but preferably 90 degrees to 150 degrees. This is because it is easy to form a uniform concentric angle within this range.

  According to the second embodiment, the surface area of the getter layer 17 with respect to the arrangement space of the non-evaporable getter 11 can be increased as compared with the case where the getter layer 17 is planar (see FIG. 3). As in the first embodiment, the tube 1 can increase the gas adsorption capability with respect to the arrangement space of the non-evaporable getter 11 and can stably maintain a low degree of vacuum in the tube over a long period of time.

(Third embodiment)
FIG. 5 shows a non-evaporable getter 11 used in the X-ray tube 1 according to the third embodiment. The non-evaporable getter 11 used in the third embodiment is formed by alternately forming a mountain-shaped fold 21 and a valley fold 23 at an angle β every predetermined length from the flat plate-shaped original non-evaporable getter 11A shown in FIG. It has a so-called bellows shape as a whole. The angle β of the mountain fold 21 and the valley fold 23 is about 20 degrees in the third embodiment, but preferably the surface area of the getter layer 17 is further increased by increasing the number of folds to 20 degrees or less. Can do.

  Also in the third embodiment, since the surface area of the getter layer 17 with respect to the arrangement space of the non-evaporable getter 11 can be increased, the same operational effects as those of the first embodiment described above can be obtained.

(Fourth embodiment)
FIG. 6 shows a non-evaporable getter 11 used in the X-ray tube 1 according to the fourth embodiment. The non-evaporable getter 11 used in the fourth embodiment is formed by connecting a plurality of non-evaporable getter units 12 formed in a curved shape to the flat plate-shaped original non-evaporable getter 11A shown in FIG. As in one embodiment, the whole is formed in a spiral shape.

  According to the fourth embodiment, since the surface area of the getter layer 17 with respect to the arrangement space of the non-evaporable getter 11 can be increased, the same operational effects as the first embodiment can be obtained and the original non-evaporable getter can be obtained. Since the non-evaporable getter unit 12 in which 11A is formed in a curved shape is simply connected in sequence, the manufacture is easy.

(Fifth embodiment)
FIG. 7 shows a non-evaporable getter 11 used in the X-ray tube 1 according to the fifth embodiment. The non-evaporable getter 11 used in the fifth embodiment is a flat original non-evaporable getter 11A shown in FIG. 3, and a plurality of non-evaporable getter units 12 having different horizontal dimensions are prepared. A plurality of non-evaporable getter units 12 are connected in series so as to form at right angles to form a non-evaporable getter 11 having a concentric winding shape as a whole as in the second embodiment. Is.

  According to the fifth embodiment, since the surface area of the getter layer 17 with respect to the arrangement space of the non-evaporable getter 11 can be increased, the same operational effects as the first embodiment can be obtained, and also shown in FIG. The non-evaporable getter units 12 having different dimensions of the original non-evaporable getter 11 are simply arranged in sequence, and processing such as bending and bending is unnecessary, so that the manufacture is further facilitated.

(Sixth embodiment)
FIG. 8 shows a non-evaporable getter 11 used in the X-ray tube 1 according to the sixth embodiment. The non-evaporable getter 11 used in the sixth embodiment is formed by winding a getter layer 17 formed only on one side of a metal plate 15 in a spiral shape as in the first embodiment. .

  According to the sixth embodiment, since the surface area of the getter layer 17 with respect to the arrangement space of the non-evaporable getter 11 can be increased, the gas adsorption capability with respect to the arrangement space of the non-evaporable getter 11 can be increased as in the first embodiment. It is possible to maintain a low degree of vacuum in the tube stably for a long period of time, and the getter layer 17 is formed only on one side of the metal plate 15, so that the bending process of the metal plate 15 is the first embodiment. Easier to manufacture and easier to manufacture.

(Seventh embodiment)
FIG. 9 shows a non-evaporable getter 11 used in the X-ray tube 1 according to the seventh embodiment. The non-evaporable getter 11 used in the seventh embodiment has a plurality of original non-evaporable getters 11A in which getter layers 17 are formed on both sides of a flat metal plate 15 as shown in FIG. The end portions 15 a and 15 b of each metal plate 15 are aligned, and the end portions 15 a and 15 b are connected to the connecting member 19 by welding. In the seventh embodiment, the getter layers 17 of the original non-evaporable getters 11A adjacent to each other are arranged in close contact with each other.

  According to the seventh embodiment, since the surface area of the getter layer 17 with respect to the arrangement space of the non-evaporable getter 11 can be increased, the same effects as those of the first embodiment can be achieved.

  Furthermore, since a plurality of the non-evaporable getters 11A shown in FIG. 3 are arranged in parallel and welded to the connecting member 19 without being bent or folded, the manufacturing can be facilitated.

  In this embodiment, the adjacent getter layers 17 are arranged in close contact with each other. However, since gas molecules can pass through the getter layer 17, they do not affect the adsorption of the gas molecules. Therefore, the getter material can be arranged at a higher density than the case where the getter layers 17 and 17 are arranged with a space between the adjacent getter layers 17, and the adsorption ability of the gas molecules in the predetermined space can be enhanced.

(Eighth embodiment)
FIG. 10 shows a non-evaporable getter 11 used in the X-ray tube 1 according to the eighth embodiment. The non-evaporable getter 11 used in the eighth embodiment is replaced with a mountain fold 21 and a valley fold 23 of the non-evaporable getter 11 according to the third embodiment shown in FIG. Valley-shaped bends 27 are alternately formed.

  According to the eighth embodiment, since the surface area of the getter layer 17 with respect to the arrangement space of the non-evaporable getter 11 can be increased, the same operational effects as those of the third embodiment described above can be achieved.

  The above-described embodiment has been presented as an example, and is not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  For example, as in the sixth embodiment shown in FIG. 8, the getter layer 17 may be formed only on one side of the metal plate 15 also in the second to fifth embodiments and the seventh and eighth embodiments. good.

  In the first, second, fourth, fifth and sixth embodiments, the number of spirals or concentric turns of the non-evaporable getter 11 may be one or two, or 5 to 10 turns. The number of windings is not limited. If the number of windings is large, the surface area of the getter layer 17 is increased accordingly, so that the adsorption ability of gas molecules can be increased.

  Further, the non-evaporable getter 11 is not limited to being formed into a round shape or a square shape with one turn, but a curved shape such as a half turn or a quarter turn, or an L shape as compared with a flat plate shape. What is necessary is just to make the surface area of the getter layer 17 large.

  In the X-ray tube 1 shown in FIG. 1, the non-evaporable getter 11 is not limited to being attached to the terminals 3 a and 3 b of the cathode 3, but may be provided on the cathode support 9 or other space portion on the cathode 3 side. The attachment position of the non-evaporable getter 11 is not limited.

  In each embodiment, when the non-evaporable getter 11 is configured to be energized via an energizing terminal, the non-evaporable getter 11 is attached to a terminal (pin) that is made independent inside the vacuum envelope 13. With this structure, it can be re-energized after a certain period of use. Since the energizing current can be increased and the getter material can be reactivated after a certain period of use, gas molecules can be adsorbed over a longer period of time.

  Furthermore, in the above-described embodiment, the fixed anode X-ray tube 1 has been described as an example. However, the present invention can also be applied to a rotary anode X-ray tube in the same manner in the vacuum envelope 13.

  DESCRIPTION OF SYMBOLS 1 ... X-ray tube apparatus, 3 ... Cathode, 7 ... Anode target, 11 ... Non-evaporable getter, 12 ... Non-evaporable getter unit, 13 ... Vacuum envelope, 15 ... Metal plate, 15a ... One end part, 15b ... The other end, 17: getter layer (getter material), 21: mountain fold, 23 ... valley fold, 25 ... mountain-shaped bending, 27 ... valley-shaped bending.

Claims (11)

A cathode that emits thermal electrons;
An anode target that emits X-rays when electrons emitted from the cathode collide, and an anode having an anode extension connected to the anode target;
An electrically insulating vacuum envelope that houses the anode target and the cathode and maintains insulation between the anode target and the cathode;
A non-evaporable getter having a metal plate provided in the vacuum envelope and having a getter material that adsorbs gas molecules held on the surface thereof,
The non-evaporable getter is an X-ray tube in which the metal plate is bent in a curved shape or bent at an angle.   2. The X-ray tube according to claim 1, wherein the non-evaporable getter is disposed on an inner peripheral side of the other end portion in a state in which one end portion of the metal plate is wound one or more times around the other end portion. .   The X-ray tube according to claim 2, wherein the non-evaporable getter is formed of a curved surface in which the metal plate is continuous.   The X-ray tube according to claim 2, wherein the non-evaporable getter has the metal plate folded at a predetermined interval at a right angle or an obtuse angle.   2. The X-ray tube according to claim 1, wherein the non-evaporable getter is formed by alternately bending or folding the metal plate into a peak and a valley.   6. The X-ray tube according to claim 5, wherein the non-evaporable getter is formed by alternately bending the metal plate into a mountain and a valley at an angle of 20 degrees or less. A cathode that emits thermal electrons;
An anode target that emits X-rays when electrons emitted from the cathode collide, and an anode having an anode extension connected to the anode target;
An electrically insulating vacuum envelope that houses the anode target and the cathode and maintains insulation between the anode target and the cathode;
A non-evaporable getter composed of a non-evaporable getter unit, which is provided in the vacuum envelope and has a metal plate on which a getter material that adsorbs gas molecules is held,
In the non-evaporable getter, a plurality of non-evaporable getter units are arranged in series, the ends of the metal plates of the adjacent non-evaporable getter units are connected to each other, and the whole is wound more than once. One end portion of the metal plate of the non-evaporable getter unit on one end side is disposed on the inner peripheral side of the other end portion of the metal plate of the non-evaporable getter unit on the other end side. Wire tube.   The X-ray tube according to claim 7, wherein each of the non-evaporable getter units has the metal plate bent in a curved shape.   The X-ray tube according to claim 7, wherein the adjacent non-evaporable getter units are connected to form an angle with each other. A cathode that emits thermal electrons;
An anode target that emits X-rays when electrons emitted from the cathode collide, and an anode having an anode extension connected to the anode target;
An electrically insulating vacuum envelope that houses the anode target and the cathode and maintains insulation between the anode target and the cathode;
A non-evaporable getter composed of a non-evaporable getter unit provided in the vacuum envelope and having a metal plate holding a getter material that adsorbs gas molecules on its surface;
An X-ray tube in which the non-evaporable getter is provided with a plurality of non-evaporable getter units in parallel.   The X-ray tube according to claim 1, wherein the non-evaporable getter or the non-evaporable getter unit holds the getter material on both surfaces of the metal plate.

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