EP0369529A1 - X-ray tube - Google Patents

X-ray tube Download PDF

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Publication number
EP0369529A1
EP0369529A1 EP89202836A EP89202836A EP0369529A1 EP 0369529 A1 EP0369529 A1 EP 0369529A1 EP 89202836 A EP89202836 A EP 89202836A EP 89202836 A EP89202836 A EP 89202836A EP 0369529 A1 EP0369529 A1 EP 0369529A1
Authority
EP
European Patent Office
Prior art keywords
cathode
ray tube
exit window
anode
radiation exit
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.)
Withdrawn
Application number
EP89202836A
Other languages
German (de)
French (fr)
Inventor
Rolf Behling
Wolfgang Köster
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.)
Philips Intellectual Property and Standards GmbH
Koninklijke Philips NV
Original Assignee
Philips Patentverwaltung GmbH
Philips Gloeilampenfabrieken NV
Koninklijke Philips Electronics NV
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 Philips Patentverwaltung GmbH, Philips Gloeilampenfabrieken NV, Koninklijke Philips Electronics NV filed Critical Philips Patentverwaltung GmbH
Publication of EP0369529A1 publication Critical patent/EP0369529A1/en
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/02—Details
    • H01J35/04—Electrodes ; Mutual position thereof; Constructional adaptations therefor
    • H01J35/06—Cathodes
    • H01J35/066—Details of electron optical components, e.g. cathode cups

Definitions

  • the invention relates to an X-ray tube with an anode and a cathode, which are located in an evacuated metal piston provided with a radiation exit window and, in operation, carry positive or negative high voltage with respect to the latter.
  • Such an X-ray tube is known from DE-PS 24 55 974.
  • Fig. 1 shows a rotating anode X-ray tube of this type in a partially broken representation.
  • the X-ray tube comprises an evacuated tube piston 1 made of metal, hereinafter referred to as a metal piston, in which a disk-shaped rotating anode 2 and a cathode 3 are located.
  • the anode 2 and the cathode 3 are mounted in the metal piston in a manner not shown in more detail or fastened thereon. This storage takes place in each case via an insulator, not shown.
  • the anode or cathode has a positive or negative high-voltage potential with respect to the metal piston 1 which is at earth potential.
  • Such radiation exit windows are relatively thin and preferably consist of beryllium, which weakens the X-rays only slightly. This window heats up relatively strongly during operation of the X-ray tube.
  • This object is achieved in that the cathode is provided, at least in its region adjacent to the radiation exit window, with a bead which extends in the axial direction to shield the radiation exit window from the electrons emitted by the cathode.
  • the bead provided according to the invention in the region of the cathode which faces the radiation exit window produces an electrical field distribution in the operating state which influences the paths of the electrons emitted from the cathode in such a way that they can practically no longer reach the radiation exit window.
  • the bead also reduces the proportion of the electrons emitted from the cathode, which hit the tube piston directly - or after one or more reflections, in particular at the anode - so that the current flowing through the tube piston in the operating state is a change with a high internal generator resistance of the cathode voltage is reduced.
  • FIG. 2 shows the cathode of a so-called double focus X-ray tube, ie an X-ray tube which has two heating filaments lying next to one another, the longitudinal direction of which is approximately perpendicular to the radiation exit window 4 runs.
  • the two heating filaments (not shown in more detail) are located in mutually inclined dies (recesses) that are inclined towards one another.
  • the two dies, of which only the rear die 31 is visible in the drawing, are separated from one another by a central web 32 which, in the cross-sectional illustration, also covers the filament located at the lowest part 33 of the die 31.
  • the bead 34 extends in the axial direction and covers an arc of approx. 90 °°, has a thickness of 3 mm and a maximum height of 4 mm (Fig. 2 is not to scale).
  • the filament or the die must be designed in such a way that the electrons hit the intended area of the anode during the predetermined deflection by the bead 34.
  • the bead 34 practically prevents electrons emitted from the cathode from hitting the window directly. Only electrons reflected at the anode 2 still reach the radiation exit window. The reduction in the number (and in part also in the energy) of the electrons hitting the radiation exit window also reduces its heating. In addition, the bead means that fewer electrons can get onto the metal bulb of the X-ray tube. This leads to a reduction in the unwanted current through the metal flask of the x-ray tube.

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  • X-Ray Techniques (AREA)

Abstract

The invention relates to an X-ray tube having an anode and a cathode which are located in an evacuated metal envelope provided with a beam exit window and carry positive and negative high voltage, respectively, with respect to this envelope in operation. In such an X-ray tube, the heating of the beam exit window can be reduced by the fact that the cathode is provided at least in its area adjacent to the beam exit window with a bead extending in the axial direction for shielding the beam exit window against the electrons emitted by the cathode. …<IMAGE>…

Description

Die Erfindung betrifft eine Röntgenröhre mit einer Anode und einer Kathode, die sich in einem evakuierten, mit einem Strahlenaustrittsfenster versehenen Metallkolben befinden und im Betrieb gegenüber diesem positive bzw. negative Hochspannung führen.The invention relates to an X-ray tube with an anode and a cathode, which are located in an evacuated metal piston provided with a radiation exit window and, in operation, carry positive or negative high voltage with respect to the latter.

Eine solche Röntgenröhre ist aus der DE-PS 24 55 974 bekannt.Such an X-ray tube is known from DE-PS 24 55 974.

Fig. 1 zeigt eine Drehanoden-Röntgenröhre dieser Bauart in einer teilweise aufgebrochenen Darstellung. Die Röntgenröhre umfaßt einen evakuierten Röhrenkolben 1 aus Metall, im folgenden als Metallkolben bezeichnet, in dem sich eine scheibenförmige Drehanode 2 und eine Kathode 3 befinden. Die Anode 2 bzw. die Kathode 3 sind auf nicht näher dargestellte Weise in dem Metallkolben gelagert bzw. daran befestigt. Diese Lagerung erfolgt jeweils über einen nicht näher dargestellten Isolator. Im Betriebszu­stand führen Anode bzw. Kathode gegenüber dem auf Erdpo­tential befindlichen Metallkolben 1 positives bzw. negati­ves Hochspannungspotential.Fig. 1 shows a rotating anode X-ray tube of this type in a partially broken representation. The X-ray tube comprises an evacuated tube piston 1 made of metal, hereinafter referred to as a metal piston, in which a disk-shaped rotating anode 2 and a cathode 3 are located. The anode 2 and the cathode 3 are mounted in the metal piston in a manner not shown in more detail or fastened thereon. This storage takes place in each case via an insulator, not shown. In the operating state, the anode or cathode has a positive or negative high-voltage potential with respect to the metal piston 1 which is at earth potential.

Die auf der Drehanode in dem der Kathode 3 gegenüberlie­genden Bereich erzeugten Röntgenstrahlen treten durch ein in dem Metallkolben 1 vorgesehenes Strahlenaustritts­fenster 4 aus. Derartige Strahlenaustrittsfenster sind relativ dünn und bestehen vorzugsweise aus Beryllium, das die Röntgenstrahlung nur wenig schwächt. Im Betrieb der Röntgenröhre erwärmt sich dieses Fenster relativ stark.The X-rays generated on the rotating anode in the area opposite the cathode 3 exit through a radiation exit window 4 provided in the metal bulb 1. Such radiation exit windows are relatively thin and preferably consist of beryllium, which weakens the X-rays only slightly. This window heats up relatively strongly during operation of the X-ray tube.

Es ist Aufgabe der vorliegenden Erfindung eine Röntgen­röhre der eingangs genannten Art derart auszugestalten, daß die Erwärmung verringert wird. Diese Aufgabe wird erfindungsgemäß dadurch gelöst, daß die Kathode zumindest in ihrem dem Strahlenaustrittsfenster benachbarten Bereich mit einem sich in axialer Richtung erstreckenden Wulst zur Abschirmung des Strahlenaustrittsfensters gegenüber den von der Kathode emitierten Elektronen versehen ist.It is an object of the present invention to design an X-ray tube of the type mentioned at the outset in such a way that the heating is reduced. This object is achieved in that the cathode is provided, at least in its region adjacent to the radiation exit window, with a bead which extends in the axial direction to shield the radiation exit window from the electrons emitted by the cathode.

Der erfindungsgemäß vorgesehene Wulst in dem Bereich der Kathode, der dem Strahlenaustrittsfenster zugewandt ist, ruft im Betriebszustand eine elektrische Feldverteilung hervor, die die Bahnen der aus der Kathode emittierten Elektonen so beeinflußt, daß sie praktisch nicht mehr direkt zum Strahlenaustrittsfenster gelangen können. Darüberhinaus verringert der Wulst auch den Anteil der aus der Kathode emitierten Elektronen, die direkt - oder nach einer oder mehreren Reflexionen insbesondere an der Anode - auf den Röhrenkolben treffen, so daß der im Betriebs­zustand über den Röhrenkolben fließende Strom, der bei hohem Generatorinnenwiderstand eine Veränderung der Katho­denspannung bewirkt, verringert wird.The bead provided according to the invention in the region of the cathode which faces the radiation exit window produces an electrical field distribution in the operating state which influences the paths of the electrons emitted from the cathode in such a way that they can practically no longer reach the radiation exit window. In addition, the bead also reduces the proportion of the electrons emitted from the cathode, which hit the tube piston directly - or after one or more reflections, in particular at the anode - so that the current flowing through the tube piston in the operating state is a change with a high internal generator resistance of the cathode voltage is reduced.

Die Erfindung wird nachstehend anhand der Zeichnung näher erläuters. Es zeigen

  • Fig. 1 die bekannte Röntgenröhre in schematischer Darstellung und
  • Fig. 2 einen Ausschnitt aus einer erfindungsgemäßen Röntgenröhre
The invention is explained in more detail below with reference to the drawing. Show it
  • Fig. 1 shows the known X-ray tube in a schematic representation
  • Fig. 2 shows a section of an X-ray tube according to the invention

In Figur 2 ist die Kathode einer sogenannten Doppelfokus-­Röntgenröhre dargestellt, d.h. einer Röntgenröhre, die zwei nebeneinanderliegende Heizfäden aufweist, deren Längsrichtung etwa senkrecht zum Strahlenaustrittsfenster 4 verläuft. Die beiden nicht näher dargestellten Heizfäden befinden sich in schräg zueinander geneigten, mehrfach abgestuften Gesenken (Ausnehmungen). Die beiden Gesenke von denen in der Zeichnung nur das hintere Gesenk 31 sichtbar ist, sind durch einen Mittelsteg 32 voneinander getrennt, der in der Querschnittsdarstellung auch den am untersten Teil 33 des Gesenkes 31 befindlichen Heizfaden verdeckt.FIG. 2 shows the cathode of a so-called double focus X-ray tube, ie an X-ray tube which has two heating filaments lying next to one another, the longitudinal direction of which is approximately perpendicular to the radiation exit window 4 runs. The two heating filaments (not shown in more detail) are located in mutually inclined dies (recesses) that are inclined towards one another. The two dies, of which only the rear die 31 is visible in the drawing, are separated from one another by a central web 32 which, in the cross-sectional illustration, also covers the filament located at the lowest part 33 of the die 31.

Auf der Drehanode 2 zugewandten Stirnfläche, die in einer zur Drehachse der Drehanode senkrechten Ebene liegt, befindet sich in dem Bereich der dem Strahlenaustritts­fenster 4 benachbart ist, ein kreisbogenförmiger Wulst 34. Der Wulst 34 erstreckt sich in axialer Richtung, bedeckt einen Bogen von ca. 90°°, hat eine Dicke von 3 mm und eine größte Höhe von 4 mm (Fig.2 ist nicht maßstäblich). Dadurch wird das Feld um den Kathodenkopf (das ist der Anode zugewandte Teil der Kathode) so beein­flußt, daß die aus dem untersten Teil 33 des Gesenkes aus­tretenden Elektronen seitlich (nach rechts) abgelenkt werden und danach auf die Anode treffen. Es versteht sich von selbst, daß der Heizfaden bzw. das Gesenk so gestaltet sein muß, daß die Elektronen bei der vorgegebenen Ablenkung duch den Wulst 34 auf den vorgesehenen Bereich der Anode auftreffen.On the end face facing the rotating anode 2, which lies in a plane perpendicular to the axis of rotation of the rotating anode, there is an arc-shaped bead 34 in the area adjacent to the radiation exit window 4. The bead 34 extends in the axial direction and covers an arc of approx. 90 °°, has a thickness of 3 mm and a maximum height of 4 mm (Fig. 2 is not to scale). This influences the field around the cathode head (this is the part of the cathode facing the anode) in such a way that the electrons emerging from the bottom part 33 of the die are deflected laterally (to the right) and then hit the anode. It goes without saying that the filament or the die must be designed in such a way that the electrons hit the intended area of the anode during the predetermined deflection by the bead 34.

Der Wulst 34 verhindert praktisch, daß aus der Kathode emitierte Elektronen direkt auf das Fenster auftreffen können. Lediglich an der Anode 2 reflektierte Elektronen gelangen noch auf das Strahlenaustrittsfenster. Die Verringerung der Zahl (und teilweise auch der Energie) der Elektronen, die auf das Strahlenaustrittsfenster treffen, verringert auch dessen Erwärmung. Darüberhinaus bewirkt der Wulst, daß weniger Elektronen auf den Metallkolben der Röntgenröhre gelangen können. Dies führt zu einer Verringerung des unerwünschten Stromes über den Metall­ kolben der Röntgenröhre.The bead 34 practically prevents electrons emitted from the cathode from hitting the window directly. Only electrons reflected at the anode 2 still reach the radiation exit window. The reduction in the number (and in part also in the energy) of the electrons hitting the radiation exit window also reduces its heating. In addition, the bead means that fewer electrons can get onto the metal bulb of the X-ray tube. This leads to a reduction in the unwanted current through the metal flask of the x-ray tube.

Die Erfindung wurde vorstehend in Verbindung mit einer Drehanoden-Röntgenröhre erläutert; sie ist jedoch auch bei Festanoden-Röntgenröhren anwendbar.The invention has been explained above in connection with a rotating anode X-ray tube; however, it can also be used with fixed anode X-ray tubes.

Claims (2)

1. Röntgenröhre mit einer Anode und einer Kathode, die sich in einem evakuierten, mit einem Strahlenaustritts­fenster versehenen Metallkolben befinden und im Betrieb gegenüber diesem positive bzw. negative Hochspannung führen,
dadurch gekennzeichnet, daß die Kathode (3) zumindest in ihrem dem Strahlenaustrittsfenster (4) benachbarten Bereich mit einem sich in axialer Richtung erstreckenden Wulst (34) zur Abschirmung des Strahlenaustritts­fensters (4) genüber den von der Kathode emittierten Elektronen versehen ist.1. X-ray tube with an anode and a cathode, which are located in an evacuated metal bulb provided with a radiation exit window and, in operation, carry positive or negative high voltage with respect to it,
characterized in that the cathode (3) is provided, at least in its region adjacent to the radiation exit window (4), with a bead (34) extending in the axial direction for shielding the radiation exit window (4) from the electrons emitted by the cathode. 2. Röntgenröhre nach Anspruch 1,
dadurch gekennzeichnet, daß sie als Drehanoden-Röntgen­röhre ausgebildet ist.2. X-ray tube according to claim 1,
characterized in that it is designed as a rotating anode X-ray tube.
EP89202836A 1988-11-14 1989-11-08 X-ray tube Withdrawn EP0369529A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3838539A DE3838539A1 (en) 1988-11-14 1988-11-14 X-RAY TUBES
DE3838539 1988-11-14

Publications (1)

Publication Number Publication Date
EP0369529A1 true EP0369529A1 (en) 1990-05-23

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ID=6367130

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EP89202836A Withdrawn EP0369529A1 (en) 1988-11-14 1989-11-08 X-ray tube

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US (1) US5008917A (en)
EP (1) EP0369529A1 (en)
JP (1) JPH02223143A (en)
DE (1) DE3838539A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5511104A (en) * 1994-03-11 1996-04-23 Siemens Aktiengesellschaft X-ray tube

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05119625A (en) * 1991-10-28 1993-05-18 Minolta Camera Co Ltd Magnetic brush developing device
JP4786285B2 (en) * 2005-10-07 2011-10-05 浜松ホトニクス株式会社 X-ray tube
DE102011003943A1 (en) * 2011-02-10 2012-08-16 Siemens Aktiengesellschaft Cathode for use in X-ray tube, has emitter arranged at cathode head base, which emits electrons upon application of heating voltage, where emitter is arranged close to one of two cathode head walls of different height

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2107597A (en) * 1932-06-27 1938-02-08 Philips Nv High voltage discharge tube
US3549931A (en) * 1968-12-04 1970-12-22 Torr Lab Inc X-ray transmissive window assembly
US4309637A (en) * 1979-11-13 1982-01-05 Emi Limited Rotating anode X-ray tube

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2926270A (en) * 1957-12-30 1960-02-23 Gen Electric Rotating anode x-ray tube
US3250916A (en) * 1963-06-14 1966-05-10 Machlett Lab Inc Stereo x-ray device
DE2455974C3 (en) * 1974-11-27 1979-08-09 Philips Patentverwaltung Gmbh, 2000 Hamburg Rotating anode x-ray tube
US4698835A (en) * 1984-05-31 1987-10-06 Kabushiki Kaisha Toshiba X-ray tube apparatus

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2107597A (en) * 1932-06-27 1938-02-08 Philips Nv High voltage discharge tube
US3549931A (en) * 1968-12-04 1970-12-22 Torr Lab Inc X-ray transmissive window assembly
US4309637A (en) * 1979-11-13 1982-01-05 Emi Limited Rotating anode X-ray tube

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5511104A (en) * 1994-03-11 1996-04-23 Siemens Aktiengesellschaft X-ray tube

Also Published As

Publication number Publication date
JPH02223143A (en) 1990-09-05
US5008917A (en) 1991-04-16
DE3838539A1 (en) 1990-05-17

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