EP0215034B1 - Tube a rayons x avec une partie metallique cylindrique entourant l'anode et la cathode - Google Patents

Tube a rayons x avec une partie metallique cylindrique entourant l'anode et la cathode Download PDF

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Publication number
EP0215034B1
EP0215034B1 EP86901329A EP86901329A EP0215034B1 EP 0215034 B1 EP0215034 B1 EP 0215034B1 EP 86901329 A EP86901329 A EP 86901329A EP 86901329 A EP86901329 A EP 86901329A EP 0215034 B1 EP0215034 B1 EP 0215034B1
Authority
EP
European Patent Office
Prior art keywords
ceramic insulator
ray tube
ceramic
cathode
anode
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP86901329A
Other languages
German (de)
English (en)
Other versions
EP0215034A1 (fr
Inventor
Engelbert Berger
Dieter-W. Zickert
Peter Gutknecht
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
GESELLSCHAFT fur ELEKTRONISCHE ROHREN COMET BERN
Original Assignee
GESELLSCHAFT fur ELEKTRONISCHE ROHREN COMET BERN
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by GESELLSCHAFT fur ELEKTRONISCHE ROHREN COMET BERN filed Critical GESELLSCHAFT fur ELEKTRONISCHE ROHREN COMET BERN
Priority to AT86901329T priority Critical patent/ATE40767T1/de
Publication of EP0215034A1 publication Critical patent/EP0215034A1/fr
Application granted granted Critical
Publication of EP0215034B1 publication Critical patent/EP0215034B1/fr
Expired legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/02—Details
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/02—Details
    • H01J35/16—Vessels; Containers; Shields associated therewith

Definitions

  • the present invention relates to an X-ray tube with a cylindrical metal part surrounding the anode and the cathode, from which at least one of the electrodes anode and cathode is electrically insulated by means of a disk-shaped ceramic insulator which is arranged at an axial end of the metal part.
  • Such an X-ray tube is known from DE-A-2855905.
  • Known x-ray tubes of this type have shields in the interior of the cylindrical metal part, which are shaped and arranged in such a way that the electrical field resulting on the inner surfaces of the ceramic insulators points in its direction away from the insulator surface against the interior of the x-ray tube. This largely prevents the inside surfaces of the ceramic insulators from being inevitable from field emission electrons from becoming electrically charged as a result of secondary electron emission, thereby reducing the dielectric strength of the X-ray tube.
  • the object of the present invention is to provide an X-ray tube of the type mentioned in the introduction, in which the shields mentioned are dispensable and yet the electrical field on the inner surface of the or each ceramic insulator points in its direction away from the insulator surface against the interior of the tube.
  • the disk-shaped ceramic insulator has a step-like or ramp-like design in radial directions on its axial end surface facing away from the interior of the X-ray tube, in order to form an annular axial recess which is filled with an insulating material whose dielectric constant is smaller than that of the Ceramic material, and that in the case of a ceramic insulator isolating the anode from the metal part, the recess is arranged radially inside and in the case of a ceramic insulator isolating the cathode from the metal part, the recess is arranged radially outside.
  • This configuration of the X-ray tube ensures, in a surprisingly simple manner, that the direction of the electrical field on the inner insulator surface points away from the insulator surface into the interior of the tube.
  • the electrical field strength is reduced at the locations where the field emission primarily occurs, namely at the so-called trip points.
  • the tripie point is the solder connection between the ceramic insulator and the high-voltage lead in the center of the insulator.
  • the triple point lies in the soldering connection between the outer circumference of the ceramic insulator and the cylindrical metal part.
  • the insulating material filling the recess of the ceramic insulator can be a part of a rubber-elastic disc which is pressed in the axial direction onto the step-shaped or ramp-shaped end surface of the ceramic insulator.
  • the x-ray tube shown has a cylindrical metal part 11 which is provided with a window 12 inserted in a vacuum-tight manner for the exit of the x-ray radiation.
  • a window 12 inserted in a vacuum-tight manner for the exit of the x-ray radiation.
  • annular disk-shaped ceramic insulator 13 At the upper axial end of the metal part 11 in FIG. 1 there is an annular disk-shaped ceramic insulator 13, the outer periphery of which is connected to the metal part 11 in a vacuum-tight manner.
  • the axial end face 16 of the ceramic insulator 13 facing away from the interior of the metal part 11 is offset radially outwards by a step 17 running in the circumferential direction, so that an annular axial depression 18 is formed on the ceramic insulator 13 adjacent to its outer circumference.
  • This depression 18 is filled by a portion 19 of a rubber-elastic washer 20, which is pressed onto the ceramic insulator 13 by means of its connecting part 21 in a manner known per se, which is not shown.
  • the rubber-elastic washer 20 has a smaller dielectric constant than the ceramic insulator 13. Expediently, there is a layer of insulation grease (not shown in FIG. 1) in the joints between the ceramic insulator 13 and the rubber-elastic washer 20 as well as between the connecting part 21 and the rubber-elastic washer 20.
  • annular disk-shaped ceramic insulator 23 At the lower axial end of the cylindrical metal part 11 in FIG. 1 there is also an annular disk-shaped ceramic insulator 23, the outer periphery of which is connected to the metal part 11 in a vacuum-tight manner.
  • the facing away from the interior of the metal part 11 The axial end face 26 of the ceramic insulator 23 is offset radially inward by a step 27 running in the circumferential direction, so that an annular axial recess 28 is formed on the ceramic insulator 23 adjacent to its inner circumference.
  • This recess 28 is completely filled by a portion 29 of a rubber-elastic washer 30.
  • the rubber-elastic washer 30 is pressed onto the ceramic insulator 23 in a manner not known per se.
  • the rubber-elastic washer 30 has a smaller dielectric constant than the ceramic insulator 23.
  • one layer (not shown) of insulation grease In the joints between the ceramic insulator 23 and the rubber-elastic washer 30 as well as between the connecting part 31 and the rubber-elastic washer 30 there is expediently one layer (not shown) of insulation grease.
  • the metal part 11 is connected to earth potential, while a voltage which is negative with respect to the earth potential is applied to the cathode 15 through the connection part 21 and a voltage which is positive with respect to the earth potential is applied through the connection part 31 to the anode 25.
  • potential lines are then set, such as, for. B. are indicated by the dashed lines 32 and 33 in Fig. 1.
  • the potential lines 32 in the region of the ceramic insulator 13 assume a diverging profile that deviates from the axis-parallel direction, in such a way that on the flat inner end surface 34 of the Ceramic insulator 13 which have electrical field vectors 35, which are always at right angles to the potential lines 32, away from the ceramic insulator 13 against the interior of the X-ray tube.
  • the recess 28 of the other ceramic insulator 23 which is filled with insulating material 29 with a lower dielectric constant, has the result that the potential lines 33 in the area of the ceramic insulator 23 assume a converging course and therefore the electric field vectors 36 on the flat inner end surface 37 of the ceramic insulator 23 have directions pointing away from this towards the inside of the X-ray tube.
  • the angle between the field vectors 35 and 36 on the one hand and the inner end surface 34 and 37 of the ceramic insulator 13 and 23 on the other hand is due to the difference in the dielectric constants of the ceramic material and the rubber-elastic insulating material due to the radial width and the axial depth of the recess 18 or 28 and determined by the dimensions of the ceramic insulator 13 or 23. Because both on the cathode side and on the anode side the electrical field strength points in their direction away from the inner end face of the ceramic insulator 13 and 23 into the interior of the X-ray tube, charges on the ceramic insulators 13 and 23 as well as the associated field strength increases are effectively avoided. In comparison to similar known X-ray tubes, in which the ceramic insulators each have flat outer end faces without the steps 17 and 27, the X-ray tube according to FIG. 1 has a noticeably higher joint dielectric strength.
  • the described advantages were checked and confirmed using a test X-ray tube.
  • the experimental X-ray tube with the structure shown in FIG. 1 had ceramic insulators 13 and 23 with an outside diameter of 107 mm and an inside diameter of 45 mm.
  • the axial thickness dimension of the ceramic insulators was 10 mm and was reduced to 7 mm at the location of the recess 18 or 28, so that the step 17 or 27 had a height of 3 mm.
  • the rubber-elastic washers 20 and 30 were made of silicone rubber with a dielectric constant of 3.2 and a Shore hardness of 28.
  • each rubber-elastic washer 20 and 30 were flat and parallel, and the outside diameter was 100 mm, the inside diameter 45 mm and the axial thickness 10 mm.
  • the X-ray tube could easily be operated with a voltage of up to 340 kV between the anode and cathode.
  • the ceramic insulator 113 shown in FIG. 2 for the cathode side of the X-ray tube has, on its axial end face 116 to be turned outwards, two steps 117 running in the circumferential direction, by means of which an axial recess 118 adjacent to the outer circumference of the ceramic insulator is formed.
  • the example of a ceramic insulator 213 for the cathode side of the X-ray tube shown in FIG. 3 has a ramp-shaped step 217 on its axial end face 216 to be turned outwards, by means of which an axial recess 218 adjacent to the outer circumference of the ceramic insulator is formed.
  • the ceramic insulator 123 shown in FIG. 4 for the anode side of the X-ray tube has two steps 117 running in the circumferential direction on its axial end face 126 to be turned outwards, by means of which an axial recess 128 adjacent to the inner circumference of the ceramic insulator is formed.
  • the ceramic insulator 223 for the anode side of the X-ray tube can also have a ramp-shaped step 227 on the axial end face to be turned outwards, so that an axial recess 228 adjacent to the inner circumference of the ceramic insulator is formed.
  • the depressions 118, 218, 128 and 228 of the ceramic insulators 113, 213, 123 and 223 according to FIGS. 2 to 5 are each made with rubber-elastic insulating material and its dielectric during assembly or installation of the X-ray tube constant is smaller than that of the ceramic material, completely filled.
  • X-ray tubes in which the cathode or the anode is electrically conductively connected to the cylindrical metal part.
  • the cathode or the anode is electrically conductively connected to the cylindrical metal part.
  • only the other anode or cathode is insulated from the cylindrical metal part by a ceramic insulator.
  • the invention is also applicable to such X-ray tubes in that the then only existing ceramic insulator in the manner described above is provided on its axial end surface facing away from the inside of the X-ray tube with a depression which is completely filled with an insulating material whose dielectric constant is smaller than that of the ceramic material is.

Landscapes

  • X-Ray Techniques (AREA)
  • Microwave Tubes (AREA)

Claims (5)

1. Tube radiogène avec un élément métallique cylindrique entourant l'anode et la cathode, dont au moins l'une des électrodes anode et cathode est électriquement isolée au moyen d'un isolateur en céramique en forme de disque qui est disposé à une extrémité axiale de l'élément métallique, caractérisé en ce que l'isolateur en céramique en forme de disque (13; 23; 113; 123; 213; 223) est réalisé, sur sa face extrême axiale (16; 26; 116; 126; 216; 226) du côté opposé à l'espace intérieur du tube radiogène, en forme de gradins ou de rampe dans des directions radiales pour la formation d'un évidement axial (18; 28; 118; 128; 218; 228) s'étendant annulairement, qui est rempli d'une matière isolante (19; 29) ayant une constante diélectrique inférieure à celle de la matière céramique, et en ce que, dans le cas d'un isolateur en céramique (13; 113; 213) isolant l'anode (25) de l'élément métallique (11 ), l'évidement est disposé radialement à l'intérieur et, dans le cas d'un isolateur en céramique (23; 123; 223) isolant la cathode (15) de l'élément métallique (11), l'évidement est disposé radialement à l'extérieur, ainsi qu'en service du tube radiogène le champ électrique (35; 36) est dévié de la face extrême intérieure (34; 37) de l'isolateur en céramique (13; 23; 113; 123; 213; 223) vers l'espace intérieur du tube radiogène et par conséquent une accumulation de charges sur la surface de l'isolateur en céramique est évitée.
2. Tube radiogène selon la revendication 1, caractérisé en ce que la matière isolante remplissant l'évidement (18; 28; 118; 128; 218; 228) de l'isolateur en céramique (13; 23; 113; 123; 213; 223) est une partie (19; 29) d'une rondelle de caoutchouc élastique (20; 30) qui est pressée contre la face extrême axiale (16; 26; 116; 126; 216; 226) réalisée en forme de gradins ou de rampe de l'isolateur en céramique.
3. Tube radiogène selon la revendication 2, caractérisé en ce que la rondelle de caoutchouc élastique (20; 30) présente, à l'état détendu, des faces extrêmes axiales sans gradins, lesdites faces extrêmes axiales ayant sensiblement les mêmes dimensions que celles de l'isolateur en céramique (13; 23; 113; 123; 213; 223).
4. Tube radiogène selon l'une des revendications 1 à 3, caractérisé en ce que la matière isolante (19; 29) remplissant l'évidement (18; 28; 118; 128; 218; 228) est du caoutchouc silicone présentant une constante diélectrique d'environ 3,2.
5. Tube radiogène selon l'une des revendications 1 à 4, dans lequel l'anode et la cathode sont isolées chacune d'un élément métallique cylindrique au moyen d'un isolateur en céramique en forme de disque, caractérisé en ce que chacun des isolateurs en céramique en forme de disque (13; 23; 113; 123; 213; 223) est réalisé, sur sa face extrême axiale (16; 26; 116; 126; 216; 226) du côté opposé à l'espace intérieur du tube radiogène, en forme de gradins ou de rampe dans des directions radiales pour la formation d'un évidement axial s'étendant annulairement, qui est rempli d'une matière isolante (19; 29) ayant une constante diélectrique inférieure à celle de la matière céramique, et en ce que l'évidement (28; 128; 228) de l'isolateur en céramique (23; 123; 223) portant l'anode (25) est disposé radialement à l'intérieur, tandis que l'évidement (18; 118; 218) de l'isolateur en céramique (13; 113; 213) portant la cathode (15) est disposé radialement à l'extérieur.
EP86901329A 1985-03-28 1986-03-13 Tube a rayons x avec une partie metallique cylindrique entourant l'anode et la cathode Expired EP0215034B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT86901329T ATE40767T1 (de) 1985-03-28 1986-03-13 Roentgenroehre mit einem die anode und die kathode umgebenden zylindrischen metallteil.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH1363/85 1985-03-28
CH1363/85A CH665920A5 (de) 1985-03-28 1985-03-28 Roentgenroehre mit einem die anode und die kathode umgebenden zylindrischen metallteil.

Publications (2)

Publication Number Publication Date
EP0215034A1 EP0215034A1 (fr) 1987-03-25
EP0215034B1 true EP0215034B1 (fr) 1989-02-08

Family

ID=4208683

Family Applications (1)

Application Number Title Priority Date Filing Date
EP86901329A Expired EP0215034B1 (fr) 1985-03-28 1986-03-13 Tube a rayons x avec une partie metallique cylindrique entourant l'anode et la cathode

Country Status (6)

Country Link
EP (1) EP0215034B1 (fr)
JP (1) JPS62502796A (fr)
AT (1) ATE40767T1 (fr)
CH (1) CH665920A5 (fr)
DE (1) DE3662079D1 (fr)
WO (1) WO1986005921A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19842467A1 (de) * 1998-09-16 2000-03-23 Siemens Ag Miniaturisierte Röntgenröhre

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4137804A1 (de) * 1991-11-16 1993-05-19 Licentia Gmbh Hochspannungsroehre
AU2002322968A1 (en) 2002-09-09 2004-03-29 Comet Holding Ag High-voltage vacuum tube
ATE414987T1 (de) 2003-12-02 2008-12-15 Comet Holding Ag Modulare röntgenröhre und verfahren zu ihrer herstellung

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE6946926U (de) * 1969-12-03 1971-07-22 C H P Mueller Gmbh Roentgenroehre mit metallkolben.
GB1458027A (en) * 1973-01-08 1976-12-08 Philips Electronic Associated Electric discharge vacuum tube
DE2506841C2 (de) * 1975-02-18 1986-07-03 Philips Patentverwaltung Gmbh, 2000 Hamburg Hochspannungs-Vakuumröhre
DE2747486A1 (de) * 1977-10-22 1979-04-26 Licentia Gmbh Roentgenroehre
DE2855905A1 (de) * 1978-12-23 1980-06-26 Licentia Gmbh Vorrichtung mit einer roentgenroehre
DE3116169A1 (de) * 1981-04-23 1982-11-11 Philips Patentverwaltung Gmbh, 2000 Hamburg Hochspannungs-vakuumroehre, insbesondere roentgenroehre

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19842467A1 (de) * 1998-09-16 2000-03-23 Siemens Ag Miniaturisierte Röntgenröhre

Also Published As

Publication number Publication date
JPS62502796A (ja) 1987-11-12
DE3662079D1 (en) 1989-03-16
CH665920A5 (de) 1988-06-15
JPH0570897B2 (fr) 1993-10-06
ATE40767T1 (de) 1989-02-15
EP0215034A1 (fr) 1987-03-25
WO1986005921A1 (fr) 1986-10-09

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