JP2009170333A - X-ray tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray tube 11 with a bonding body 22 having improved heat releasing property and field strength moderating property. <P>SOLUTION: An anode target 17 and a cathode filament 19 are arranged in a vacuum enclosure 12. The anode target 17 is supported at one end of a support 21, and the support 21 is protruded at the other end from an insulating enclosure 14 of the vacuum enclosure 12. The support 21 is bonded at the other end to the insulating enclosure 14 via the bonding body 22. The insulating enclosure 14 is stored in a tube container 28, and an insulating material 29 is filled in the tube container 28. The surface of the bonding body 22 opposed to the tube container 28 via the insulating material 29 is formed as a curved surface 44. The surface area of the bonding body 22 contacting the insulating material 29 is widened to improve the heat releasing property of the bonding body 22, and no angle portion exists to improve the electric field strength moderating property of the bonding body 22. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an X-ray tube that generates X-rays.

  A conventional X-ray tube includes a metal envelope provided with an output window that transmits X-rays in a flat portion at one end, and a vacuum envelope having an insulating envelope connected to the other end of the metal envelope. Equipped with a bowl. An anode target is disposed inside the vacuum envelope so as to face the output window, and a cathode filament that emits electrons for irradiating the anode target is disposed.

  The anode target is supported by one end of a support body, the other end side of the support body protrudes outside from the insulation envelope, and the other end side of the support body protruding from the insulation envelope becomes an insulation envelope by a joined body. It is joined. Further, a heat radiating body for radiating heat generated at the anode target and transmitted to the support is connected to the other end of the support.

The joined body that joins the support body and the insulating envelope is made by drawing a plate material made of Kovar, and the width of the tip portion facing the tube container via the insulation material is narrow. Is a plane and has a corner (see, for example, Patent Document 1).
JP-T-2001-504988 (pages 12-13, FIG. 3)

  However, in the case of a conventional X-ray tube, the joined body that joins the support and the insulating envelope is made of a plate material, and the width of the tip portion facing the tube container via the insulation material is narrow, and the tip portion Therefore, the heat generated in the anode target and transferred to the support cannot be efficiently dissipated from the tip of the joined body joined to the support to the insulating material, and the tip of the joined body. There is a problem in that the electric field strength of the portion increases, and dielectric breakdown that penetrates the insulating material from the distal end portion of the joined body toward the inner surface of the tube container occurs.

  This invention is made | formed in view of such a point, and it aims at providing the X-ray tube which can improve the thermal emission characteristic and electric field strength relaxation characteristic of a conjugate | zygote.

  The present invention relates to a metal envelope having an output window that transmits X-rays at one end, a vacuum envelope having an insulating envelope provided at the other end of the metal envelope, and the vacuum An anode target disposed in the envelope, a support that supports the anode target at one end, and the other end projects outside from the insulating envelope of the vacuum envelope, and the vacuum envelope A cathode filament that emits electrons for irradiating the anode target; a tube container that houses the insulating envelope side of the vacuum envelope; an insulating material filled in the tube container; A surface facing the tube container via the insulating material, joining the insulating envelope and the supporting body at a position where the surface is in contact with the insulating material on the other end side of the supporting body protruding from the envelope And a joined body having a curved surface.

  According to the present invention, since the surface shape of the joined body facing the tube container via the insulating material is formed into a curved surface, the surface area in contact with the insulating material can be widened to improve the heat release characteristics of the joined body, Elimination of the electric field strength can be improved.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 shows a first embodiment, in which 11 is a fixed anode type X-ray tube, and this X-ray tube 11 is provided with a vacuum envelope 12 for holding the inside in a vacuum. The vacuum envelope 12 includes a metal envelope 13 on one end side in the axial direction along the tube axis of the X-ray tube 11 and the other end side which is a portion constituting a high voltage insulating portion of the vacuum envelope 12 Insulation envelope 14 is combined.

  The metal envelope 13 has a cylindrical shape in which the outer diameter of the tip gradually decreases, the tip surface is formed flat, and an output window 15 that transmits X-rays is provided in the flat portion. For example, beryllium (Be) is used for the output window 15 as a material with little X-ray attenuation.

  The insulating envelope 14 is formed in a cylindrical shape with an insulating material such as electrically insulating ceramics.

  Further, an anode target 17 is disposed inside the vacuum envelope 12 so as to face the output window 15, a focusing electrode 18 is disposed outside the anode target 17, and a cathode filament 19 is disposed outside the focusing electrode 18. Is arranged. The cathode filament 19 is fixed to the outer periphery of the focusing electrode 18.

  Further, a support body 21 made of a material such as copper having a high thermal conductivity is disposed in the center of the vacuum envelope 12, and one end of the support body 21 is disposed inside the focusing electrode 18. The anode target 17 is supported at the tip. The other end side of the support 21 protrudes from the other end side of the insulating envelope 14 to the outside, and is joined to the insulating envelope 14 in a sealed state by a joined body 22.

  An exhaust pipe 24 for exhausting the inside of the vacuum envelope 12 through an exhaust passage 23 formed inside the support 21 is provided on the end surface of the other end of the support 21 and is also provided on the anode target 17 with a high height. A power feeding unit 26 to which a high voltage cable 25 for applying a voltage is connected is provided.

  Further, the insulating envelope 14 of the vacuum envelope 12 and the other end side of the support 21 protruding from the insulating envelope 14 are accommodated in the tube container 28. The inside of the tube container 28 is filled with an insulating material 29 which is a potting material such as silicone resin.

  In addition, the support body 21 and the joined body 22 projecting from the insulating envelope 14 are connected to the tube container 28 in the axial direction, and the heat dissipating body 31 is disposed so that the inner and outer peripheral surfaces thereof are in contact with the insulating material 29. Has been. The radiator 31 is a ceramic having a high thermal conductivity of 20 W / m · K or higher and a high voltage insulation of 10 kV / mm or higher. For example, by using aluminum nitride, a high thermal conductivity of 90 W / m · K or higher is obtained. can get.

  Further, cooling means 34 for cooling the tube container 28 is disposed on the side surface and the end surface of the tube container 28. As the cooling means 34, for example, an air-cooled type, a liquid-cooled type, or a heat pipe type can be selected according to the input of the X-ray tube 11, but an air-cooled type or a heat pipe type that is easy to maintain is preferable.

  Further, the joined body 22 is formed in a ring shape from the same material having high thermal conductivity as that of the support body 21 such as copper, and is joined to the outer peripheral face of the support body 21 and the outer end face of the insulating envelope 14. A joining surface 42 to be joined and a joining surface 43 to be joined to the heat radiating body 31 are provided. The joint surface 41 and the joint surface 42 are brazed to the support 21 and the insulating envelope 14. The surface of the joined body 22 that faces the inner surface of the tube container 28 via the insulating material 29, that is, the outer peripheral surface, is formed as a curved surface 44 that is a convex curved surface, and has a shape without corners. By making the curved surface 44, the electric field strength is reduced by about 40% from the shape having a flat tip portion and a corner portion.

  During the operation of the X-ray tube 11, electrons are emitted from the cathode filament 19 by applying a high voltage between the cathode filament 19 accommodated in the vacuum envelope 12 and the anode target 17. Is accelerated by the potential difference between the cathode filament 19 and the anode target 17 and collides with the anode target 17, and X-rays are generated and emitted from the output window 15 of the vacuum envelope 12.

  Heat is generated by the collision of electrons with the anode target 17, and the heat of the anode target 17 is transmitted to the support 21, and the insulating envelope is connected via the joined body 22 connected to the other end of the support 21. 14. The heat is dissipated and transferred to the insulating material 29 and the heat radiating body 31, and the heat is dissipated and transferred to the insulating material 29 and the tube container 28 through the heat radiating material 31. The heat transferred from the insulating material 29 and the heat radiating body 31 to the tube container 28 is radiated by the cooling means 34 that cools the side surface and the end surface of the tube container 28.

  Further, in the joined body 22, since the surface shape of the joined body 22 facing the tube container 28 is formed on the curved surface 44 through the insulating material 29, the surface area in contact with the insulating material 29 can be increased, and the joined body 22 The heat release characteristics can be improved, and the corner portions can be eliminated to improve the electric field strength relaxation characteristics.

  Moreover, the joined body 22 is formed of the same material as copper having the same thermal conductivity as the support body 21, and can improve the dissipation and heat transfer characteristics.

  Furthermore, by connecting the joined body 22 to the heat radiating body 31 that has both high thermal conductivity and high voltage insulation, it becomes easier to transfer the heat from the support 21 to the insulating material 29 and the tube container 28 and the cooling means 34. The cooling effect is enhanced.

  Further, as in the second embodiment shown in FIG. 2, the joined body 22 has a surface of the joined body 22 that faces the inner surface of the tube container 28 with an insulating material 29 interposed between a plurality of convex curved surfaces 46 and a plurality of curved surfaces 46. The concave curved surface 47 may be formed in an alternately arranged shape. That is, a so-called fin shape or corrugation is used, each tip surface is a convex curved surface 46, and each groove bottom surface is a concave curved surface 47. By adopting such a surface shape of the bonded body 22, the surface area in contact with the insulating material 29 can be increased, and heat dissipation from the bonded body 22 to the insulating material 29 and heat transfer characteristics can be improved.

It is sectional drawing of the X-ray tube which shows the 1st Embodiment of this invention. It is a partial cross section figure of the X-ray tube which shows the 2nd Embodiment of this invention.

Explanation of symbols

11 X-ray tube
12 Vacuum envelope
14 Insulated envelope
15 Output window
17 Anode target
19 Cathode filament
21 Support
22 Conjugate
28 tube container
29 Insulation material
31 Heat sink
34 Cooling means
44 Curved surface
46 Convex surface
47 Concave surface

Claims (5)

An output window that transmits X-rays at one end, and a vacuum envelope having an insulating envelope at the other end;
An anode target disposed in the vacuum envelope;
The anode target is supported at one end, and the other end protrudes outside from the insulating envelope of the vacuum envelope;
A cathode filament that is provided in the vacuum envelope and emits electrons for irradiating the anode target;
A tube container for housing the insulating envelope side of the vacuum envelope;
An insulating material filled in the tube container;
The insulating envelope and the support are joined at the other end side of the support projecting from the insulation envelope and at a position where the surface is in contact with the insulating material. An X-ray tube comprising: a joined body having opposing surface shapes formed into curved surfaces. The X-ray tube according to claim 1, wherein the surface shape of the joined body facing the tube container via the insulating material is formed of a plurality of convex curved surfaces and concave curved surfaces. The X-ray tube according to claim 1, wherein the joined body is made of the same material as the support. The X-ray tube according to any one of claims 1 to 3, further comprising a heat radiator that connects the support body and the joined body to the tube container. The X-ray tube according to any one of claims 1 to 4, further comprising cooling means for cooling the tube container.

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