EP0115731A2 - Abtaströntgenröhre - Google Patents

Abtaströntgenröhre Download PDF

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Publication number
EP0115731A2
EP0115731A2 EP83402529A EP83402529A EP0115731A2 EP 0115731 A2 EP0115731 A2 EP 0115731A2 EP 83402529 A EP83402529 A EP 83402529A EP 83402529 A EP83402529 A EP 83402529A EP 0115731 A2 EP0115731 A2 EP 0115731A2
Authority
EP
European Patent Office
Prior art keywords
filament
electron beam
ray tube
deflection
cathode
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Withdrawn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
EP83402529A
Other languages
English (en)
French (fr)
Other versions
EP0115731A3 (de
Inventor
André Plessis
Emile Gabbay
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.)
General Electric CGR SA
Original Assignee
Thomson CGR
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 Thomson CGR filed Critical Thomson CGR
Publication of EP0115731A2 publication Critical patent/EP0115731A2/de
Publication of EP0115731A3 publication Critical patent/EP0115731A3/de
Withdrawn legal-status Critical Current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
    • H01J35/14—Arrangements for concentrating, focusing, or directing the cathode ray
    • 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 present invention relates to a scanning X-ray tube, usable in radiology in particular in the field of radiodiagnostics, and particularly well suited to the field of digital radiology.
  • the object area In the latter area it is common to scan an area to be analyzed, called the object area, with an X-ray beam, this scanning being able to be carried out by a movement either of the X-ray source, or of the object area, or of an area where the image of the object is formed.
  • This movement of the X-ray source can be obtained by a displacement of the X-ray tube, by mechanical means for example, or by an action accomplished in the tube itself; the movement of the source being, in the latter case, limited in particular by the dimensional characteristics of organs contained in the X-ray tube.
  • An X-ray tube generally comprises a cathode, emitting an electron beam generated by a heated filament to which is backed an element for concentrating the electron beam and, an anodic target on which this electron beam is projected; an impact zone of these on the anode target represents the origin of the X-rays and constitutes the focal point of the tube and the source of the X-rays. Also, a movement of the X-ray source can be achieved by modifying the position, on the anode target, of the electron impact zone; it is commonly used for this purpose, means for deflecting the electron beam.
  • deflection means are generally constituted by magnetic or electrostatic lenses, arranged on the beam path or close to this path, between the catode and the anode target; they require a significant energy, the deflection energy, for their actuation necessary may be important due to the cynetic energy of the electrons.
  • an X-ray tube arranged to include such deflection means is considerably more expensive than an ordinary X-ray tube.
  • the present invention relates to a scanning X-ray tube, in which deflection of the electron beam by electrostatic effect can be obtained with a low deflection energy, without using a lens placed between the cathode and the anode target; by its arrangement, an X-ray tube according to the invention has a small increase in cost compared to an ordinary X-ray tube.
  • a scanning X-ray tube comprising a cathode, emitting an electron beam, this cathode being provided with an electron generating filament and an electron beam concentrating element, is characterized in that this concentrating element comprises at least two metallic parts electrically insulated from one another and from the filament, to allow relative to the latter their independent polarization and a deflection of the electron beam.
  • Figure 1 shows an X-ray tube 1 according to the prior art, represented by a frame in dotted lines, and containing a filament 2, a concentration element 3 formed of a metal part. lique leaned with the filament 2, and an anode target 4 partially represented; these latter elements being supported and supplied in a known manner and not shown.
  • the filament 2 and the concentrating element 3 form a symmetrical assembly, with respect to a plane perpendicular to the plane of FIG. 1 and containing an emission axis 5 passing through the filament 2; this assembly formed by the filament 2 and the concentrating element 3 constitutes a cathode C.
  • the cathode C delivers along the emission axis 5, a beam of electrons F attracted by the anode target 4, on which it determines a focus 9 from which are emitted X-rays not shown.
  • the concentration of the electron beam F, materialized by a dimension D of the focal point 9, as well as the emission axis 5 of the electron beam F are determined by the geometry of the cathode C. given this symmetry of cathode C, an electric field (not shown) is also established symmetrically around the filament 2; this symmetry of the electric field determining the electron beam F, its emission axis 5 contained in the plane of symmetry.
  • the concentration element 3 can be: either connected to the filament 2; is isolated from the latter, with respect to which in the latter case, it can be brought to a different generally negative potential. This allows, by modifying the electric field which retains its previously mentioned symmetry, to determine a different concentration, not shown, in the electron beam F; the electron beam F having retained its emission axis 5.
  • FIG. 2 shows an X-ray tube 10 in accordance with the invention, represented by a frame in dotted lines, and containing a filament 2, a concentration element 3 backed by the filament 2, and an anode target 4; as in the example of FIG. 1, the filament 2 and the concentrating element 3 constitute a cathode CI
  • the concentrating element 3 consists in particular of a first and a second metal part 12, 13, electrically isolated from one another by a insulating partition 6 secured to an insulating base 7.
  • Each of these parts 12, 13, comprising metal surfaces 14, 15, is arranged symmetrically with respect to the filament 2 and to a plane 5.8 of symmetry perpendicular to the figure; this plane, containing on the one hand the first emission axis 5, and on the other hand an axis of the filament 2 perpendicular to the plane of FIG. 2 and represented by a point 8, constitutes a plane 5.8 of symmetry of the assembly focus element 3 and filament 2.
  • the first and second metal parts 12, 13 also being electrically isolated from the filament 2, this arrangement makes it possible to apply to them, relative to the filament 2, a first and a second negative bias voltage (not shown in FIG. 2) independent of the one of the other.
  • the concentrating element 3 is thus capable of performing two functions: one for concentrating the electron beam F; the other of the deflection of this beam in a plane perpendicular to the plane 5.8 of symmetry.
  • the cathode CI can generate along the emission axis 5, an electron beam F which determines the focus 9 on the anode target 4; an electric field (not shown) being established around the filament 2 in a symmetrical manner, and the concentration of the electron beam F being ensured by the geometry of the cathode CI, as has been previously explained.
  • the cathode C1 By applying for example to the second metal part 13, a second negative bias voltage, the first bias voltage applied to the first part 12 being zero: the cathode C1 generates an electron beam Fa (shown in dotted lines), having for example a first mean direction 5a and whose impact on the anode target 4 causes a second focus 9a; the amplitude of this deflection, represented by an angle between the first emission axis 5 or rest axis 5 and this mean direction 5A, being a function of the level of the difference between these bias voltages.
  • Fa shown in dotted lines
  • n mean directions 5a, 5b, ... 5n, determining n foci 9a, 9b, ... 9n.
  • An advantage of this structure is that the metal surfaces 14, 15 serving for the deflection being very close to the filament 2, the voltages necessary for this deflection are low, (of the order of a few tens of volts to a few hundred volts). In fact, the electrons being deflected at the level of cathode C1, their cynetic energy at this level is low and little deflection energy is required; as a result, the pervéance of the transmitter is little affected.
  • Another advantage lies in that the bias voltages being low, the problems of electrical insulation are reduced and make it possible to produce a cathode CI of small bulk, the dimensions of which can be equal to those of a cathode C produced according to prior art.
  • This description constitutes a nonlimiting example of an X-ray tube 10 according to the invention, the concentrating part 3 being able to have a different shape and to comprise n metallic parts (not shown) electrically independent from each other and from the filament 2.
  • the metal parts 12, 13 can be arranged asymmetrically with respect to the filament 2, for example by giving them a different direction; this version of the invention is illustrated in FIG. 2 by a limit 11, represented in dotted lines, which gives the second metal part 13 a thickness E less than a thickness E of the first metal part 12.
  • This asymmetry determines the beam of electrons F an average direction of rest, confused for example with the second average direction 5b, or with the first average direction 5a if this asymmetry is exerted in a direction opposite to that of the nonlimiting example described.
  • an average direction of rest 5a, 5b is obtained in the absence of difference between the first and second bias voltage; a deflection of the electron beam F operating in a positive 20 or negative 21 direction, with respect to this mean direction of rest.
  • FIG. 3 shows, by way of nonlimiting example, an electrical diagram for supplying the X-ray tube 10 according to the invention.
  • the anode target 4 is connected to a + HT output of a high voltage generator 33, produced in a conventional manner; this high voltage generator 33 has an - HT output connected via a common point PC and the second external connection means 25, at one end 2a of the filament 2. This achieves the high voltage connection between the anode target 4 and the cathode CI.
  • the second and third external connection means 24, 25 are connected to outputs 37, 39 of a heating voltage generator 38 serving to supply the filament 2; this heating voltage generator 38 may include, for example, in a conventional manner, a transformer not shown.
  • the fourth and fifth external connection means 42, 43, corresponding to the first and to the second metal part 12, 13, are respectively connected to a negative output V 1 and a negative output V2 of a first and second low voltage generator 34 , 35; positive outputs 28, 29 of these low voltage generators 34, 35 being in the nonlimiting example described, also connected to the common point PC.
  • These generators 33, 34, 35, 38 which can be supplied in a conventional manner (not shown) starting from an alternating voltage source for example.
  • the low voltage generators 35, 36 can be manually adjustable, so as to supplying a variable voltage V1, V2 which is variable continuously or in leaps; these generators 35, 36 can also be adjustable remotely, by conventional means not shown or possibly programmed.
  • FIG. 4 shows a nonlimiting example, according to which the bias voltages V1, V2 can be applied to cause a deflection of the electron beam F; this deflection producing a continuous scan of the anode target 4.
  • bias voltages VI, V2 can be applied to the metal parts 12, 13 as shown in FIG. 2 from an instant t5.

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  • X-Ray Techniques (AREA)
EP83402529A 1982-12-30 1983-12-23 Abtaströntgenröhre Withdrawn EP0115731A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8222072 1982-12-30
FR8222072A FR2538948B3 (fr) 1982-12-30 1982-12-30 Tube a rayons x a balayage

Publications (2)

Publication Number Publication Date
EP0115731A2 true EP0115731A2 (de) 1984-08-15
EP0115731A3 EP0115731A3 (de) 1985-11-21

Family

ID=9280681

Family Applications (1)

Application Number Title Priority Date Filing Date
EP83402529A Withdrawn EP0115731A3 (de) 1982-12-30 1983-12-23 Abtaströntgenröhre

Country Status (2)

Country Link
EP (1) EP0115731A3 (de)
FR (1) FR2538948B3 (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0440532A1 (de) * 1990-02-02 1991-08-07 General Electric Cgr S.A. Winkelförmige Kathode mit Strahl-Ablenkung für Röntgenröhre
FR2667723A1 (fr) * 1990-10-09 1992-04-10 Gen Electric Cgr Dispositif d'obtention et de commutation de hautes tensions de polarisation d'electrodes de tube a rayons x.
FR2675629A1 (fr) * 1991-04-17 1992-10-23 Gen Electric Cgr Cathode pour tube a rayons x et tube ainsi obtenu.
DE19510048A1 (de) * 1995-03-20 1996-09-26 Siemens Ag Röntgenröhre

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4689809A (en) * 1982-11-23 1987-08-25 Elscint, Inc. X-ray tube having an adjustable focal spot

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3646379A (en) * 1970-05-18 1972-02-29 Machlett Lab Inc X-ray tube having controllable focal spot size
DE2249365A1 (de) * 1972-10-09 1974-04-25 Siemens Ag Roentgenroehre
US3875028A (en) * 1972-08-30 1975-04-01 Picker Corp Method of manufacture of x-ray tube having focusing cup with non emitting coating
US3962583A (en) * 1974-12-30 1976-06-08 The Machlett Laboratories, Incorporated X-ray tube focusing means
EP0032385A1 (de) * 1980-01-14 1981-07-22 Siemens Aktiengesellschaft Kathodenanordnung für eine Röntgenröhre
FR2536583A1 (fr) * 1982-11-23 1984-05-25 Elscint Inc Tube a rayons x comportant un foyer reglable

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3646379A (en) * 1970-05-18 1972-02-29 Machlett Lab Inc X-ray tube having controllable focal spot size
US3875028A (en) * 1972-08-30 1975-04-01 Picker Corp Method of manufacture of x-ray tube having focusing cup with non emitting coating
DE2249365A1 (de) * 1972-10-09 1974-04-25 Siemens Ag Roentgenroehre
US3962583A (en) * 1974-12-30 1976-06-08 The Machlett Laboratories, Incorporated X-ray tube focusing means
EP0032385A1 (de) * 1980-01-14 1981-07-22 Siemens Aktiengesellschaft Kathodenanordnung für eine Röntgenröhre
FR2536583A1 (fr) * 1982-11-23 1984-05-25 Elscint Inc Tube a rayons x comportant un foyer reglable

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0440532A1 (de) * 1990-02-02 1991-08-07 General Electric Cgr S.A. Winkelförmige Kathode mit Strahl-Ablenkung für Röntgenröhre
FR2658002A1 (fr) * 1990-02-02 1991-08-09 Gen Electric Cgr Cathode a deflexion en diedre pour tube a rayons x.
US5224143A (en) * 1990-02-02 1993-06-29 General Electric Cgr S.A. Dihedral deflection cathode for an x-ray tube
FR2667723A1 (fr) * 1990-10-09 1992-04-10 Gen Electric Cgr Dispositif d'obtention et de commutation de hautes tensions de polarisation d'electrodes de tube a rayons x.
EP0480796A1 (de) * 1990-10-09 1992-04-15 General Electric Cgr S.A. Vorrichtung zur Erzeugung und Umschaltung von hohen Spannungen an Röntgenröhren-Elektroden
US5200645A (en) * 1990-10-09 1993-04-06 General Electric Cgr S.A. Device for obtaining and switching high voltages applied to x-ray tube electrodes
FR2675629A1 (fr) * 1991-04-17 1992-10-23 Gen Electric Cgr Cathode pour tube a rayons x et tube ainsi obtenu.
DE19510048A1 (de) * 1995-03-20 1996-09-26 Siemens Ag Röntgenröhre
DE19510048C2 (de) * 1995-03-20 1998-05-14 Siemens Ag Röntgenröhre

Also Published As

Publication number Publication date
EP0115731A3 (de) 1985-11-21
FR2538948B3 (fr) 1985-10-18
FR2538948A1 (fr) 1984-07-06

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Inventor name: GABBAY, EMILE

Inventor name: PLESSIS, ANDRE