EP3531437A1 - Dispositif d'émission d'électrons - Google Patents

Dispositif d'émission d'électrons Download PDF

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Publication number
EP3531437A1
EP3531437A1 EP18158898.9A EP18158898A EP3531437A1 EP 3531437 A1 EP3531437 A1 EP 3531437A1 EP 18158898 A EP18158898 A EP 18158898A EP 3531437 A1 EP3531437 A1 EP 3531437A1
Authority
EP
European Patent Office
Prior art keywords
electron
grid
emission device
emitter
electron emission
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Withdrawn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
EP18158898.9A
Other languages
German (de)
English (en)
Inventor
Josef Deuringer
Jörg FREUDENBERGER
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.)
Siemens Healthcare GmbH
Original Assignee
Siemens Healthcare GmbH
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 Siemens Healthcare GmbH filed Critical Siemens Healthcare GmbH
Priority to EP18158898.9A priority Critical patent/EP3531437A1/fr
Priority to PCT/EP2019/051860 priority patent/WO2019166161A1/fr
Priority to EP19704225.2A priority patent/EP3732702A1/fr
Priority to US16/971,018 priority patent/US11373835B2/en
Publication of EP3531437A1 publication Critical patent/EP3531437A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
    • H01J1/46—Control electrodes, e.g. grid; Auxiliary electrodes
    • 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
    • H01J35/045—Electrodes for controlling the current of the cathode ray, e.g. control grids
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2235/00—X-ray tubes
    • H01J2235/06—Cathode assembly
    • H01J2235/062—Cold cathodes
    • 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
    • H01J35/064—Details of the emitter, e.g. material or structure
    • 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
    • H01J35/065—Field emission, photo emission or secondary emission cathodes
    • 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

Definitions

  • the invention relates to an electron emission device.
  • an electron emission device which is designed as a thermionic emission device is, for example in the US 8,374,315 B2 described.
  • the electron emission device comprises at least one flat emitter with at least one emission surface which emits electrons thermally when a heating voltage is applied.
  • the known electron emission device comprises at least one barrier grid, which is spaced from the emission surface of the flat emitter.
  • the barrier grid acts as a control electrode, since the emission of electrons from the material of the emission surface can be varied by applying a grid voltage. As a result, defined partial beams of the electron emission can be generated.
  • Field effect emission cathodes are eg in US 7,751,528 B2 (in particular FIG. 11b and FIG. 8) and in the publication " Multisource inverse-geometry CT. Part II. X-ray source design and prototype "(authors: V. Bogdan Neculaes et al.) In Medical Physics 43 (8), August 2016, pages 4617-4627 , in particular FIG. 7).
  • a metal grid Over a large area emitting surface of an emitter material (carbon nanotube or dispenser cathode material, such as barium oxide) is a metal grid. By applying a voltage across the complete grid, the emission current intensity of the complete area is controlled. The current flowing on the barrier grid heats the barrier grid and limits the current intensity and pulse time of the electron emission, thereby preventing damage to the barrier grid.
  • the object of the present invention is to provide an electron emission device for an X-ray tube, which allows a simple adjustment of the image quality with the lowest possible anode load.
  • the electron emission device comprising at least one electron emitter with at least one emission surface and at least one barrier grid, which is spaced from the emission surface of the electron emitter and has a predeterminable number of individually controllable grid segments.
  • the barrier grid thus forms a reliable control electrode in the electron emission device according to claim 1.
  • the segmented barrier grid is spaced from the emission surface of the electron emitter. Due to the individually controllable Grid segments can be generated different voltage patterns, by which a plurality of different electron beams can be generated. Within the scope of the invention, it is possible, for example, to alternately allow electron emission by a single grid segment. However, it is also possible that multiple grating segments, which need not necessarily be located adjacent, simultaneously allow emission of electrons from the emission surface of the electron emitter. Thus, by selectively blocking individual grid segments, the electron emission and thus the local distribution of the emitted electrons, which determines the focal spot shape, can be selectively varied. Thus, an optimal adaptation to the particular application is reliably possible.
  • the barrier grid or the grid segments always have a positive potential with respect to the emission surface of the electron emitter.
  • the grid segments in the non-emitting regions are either at the potential of the emission surface of the electron emitter or at a potential that is more negative than the potential of the electron emitter. If one chooses the potentials accordingly, then the electron beam can be deflected or focused in the emission area. The distribution of the emitted electrons is thus almost arbitrary.
  • the electron emitter is designed as a dispenser cathode (also referred to as “spindt cathode”) which emits electrons when an electric field strength is applied (claim 2).
  • dispenser cathode is understood to mean a cathode in which the carrier material is coated with a dispenser cathode material which emits electrons when an electric field strength is applied.
  • Suitable dispenser cathode materials include, for example, barium oxide (BaO) and lanthanum hexaboride (LaB 6 ).
  • the electron emitter is designed as a field effect emitter, which also emits electrons when an electric field strength is applied (claim 3).
  • the field effect emitters can be designed, for example, as CNT-based field emitters (CNT, carbon nanotubes, carbon nanotubes) or as Si-based field emitters (Si, silicon).
  • nanocrystalline diamond is according to the DE 197 27 606 A1 suitable for the production of cold cathodes.
  • the electron emitter is designed as a thermal emitter (incandescent emission) which emits electrons when a heating voltage is applied (claim 4).
  • the emission surface of the electron emitter is structured. In the case of a flat emitter having a rectangular surface, this structuring can be realized, for example, by slits on the emission surface
  • the electron emission device according to the invention or its advantageous embodiments are suitable for installation in a focus head (claim 6).
  • the electron emission device shown in the principle illustration comprises an electron emitter 2 with an emission surface 3 and with a blocking grid 5, which is spaced apart from the emission surface 3 of the electron emitter 2.
  • the invention is not limited to a single electron emitter 2 and not to a single emission surface 3.
  • the barrier grille 5 Again, a plurality of barrier grille 5 may be provided. Only for reasons of clarity, this restriction was chosen in the principle representation.
  • a freely selectable grid voltage U G1 to U GN can be applied (see FIG. 6 ).
  • To each of the grid segments G 1 to G N can therefore be applied to a different grid voltage U GN .
  • different electric fields are present in each case in the regions between the respective grid segments G 1 to G N and the emission surface 3, which leads to different emissions of electrons from the emission surface 3 of the electron emitter 1.
  • FIG. 2 to FIG. 4 shown emission distributions for the emerging from the emission surface 3 electrons achievable.
  • the grid segments G 1 to G N on the abscissa and the electron emission E is plotted on the ordinate.
  • the emission voltages shown are the grid voltages U G1 to U GN at the grid segments G 1 to G N selected such that the grid segments G 1 and G N two equally strong grid voltages U G1 and U GN applied, whereby the electron emissions E are the same.
  • the grid segments G 2 to G N-1 are blocked by the application of higher grid voltages U G2 to U GN-1 , so that no electrons emerge at the grid segments G 2 to G N-1 .
  • the grid voltages U G1 to U GN at the grid segments G 1 to G N at the in FIG. 3 different emission distribution.
  • the electron emissions E are freely selectable by applying a desired grid voltage U GN , whereby the MTF (modulation transfer function) can be influenced accordingly.
  • the MTF of the distribution of the X-ray emission resulting on an anode thus contains high-frequency components, whereby the limiting resolution of the overall system can be positively influenced (coded spot).
  • the grid segments G 2 and G 4 are completely blocked, whereas an at least partial electron emission E is possible through the grid segments G 1 , G 3 and G 5 to G N.
  • the grid segments G 1 to G 5 are differently permeable to the emitted electrons by the respectively applied grid voltages U G1 to U GN .
  • the grid segment G 1 has the lowest grid voltage U G1 and thus the highest electron emission E.
  • the highest grid voltage U G5 resulting in a correspondingly low electron emission E results.
  • the electrons emitted by the electron emitter 2 generate when hitting an in FIG. 4 not shown rotary anode an asymmetrical focal spot, which allows a higher electron beam power.
  • FIG. 5 An embodiment of an electron emission device 1 is shown in FIG FIG. 5 in longitudinal section and in FIG. 6 shown in plan view.
  • an emitter material 6 is applied, which emits 3 electrons in an emission surface (electron emission E).
  • the substrate 4 is, for example, a base body made of a technical ceramic.
  • the emitter material 6 is, for example, carbon nanotubes (CNT) or a dispenser cathode material, such as, for example, barium oxide (BaO) or lanthanum hexaboride (LaB 6 ).
  • the grid segments G 1 to G N are each driven individually with the corresponding grid voltages U G1 to U GN .
  • the grid segments G 3 to G N-1 are not shown.
  • the blocking grid 5 can be made, for example, from a tungsten sheet, from which the grid segments G 1 to G N , which form the grid structure, have been cut out by laser cutting.
  • the emission distribution E of the electrons can be arbitrarily controlled in two spatial directions.
  • the segmented barrier grid 5 from the embodiment according to FIGS. 5 and 6 is also for an optimization of the US 8,374,315 B2 known electron emission device suitable.
  • Illustrated embodiments can be achieved by the solution according to the invention in a simple way an improvement in image quality with reduced anode load by adjusting the focal spot geometry (shape and size) to the specific application.

Landscapes

  • X-Ray Techniques (AREA)
  • Cold Cathode And The Manufacture (AREA)
EP18158898.9A 2018-02-27 2018-02-27 Dispositif d'émission d'électrons Withdrawn EP3531437A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
EP18158898.9A EP3531437A1 (fr) 2018-02-27 2018-02-27 Dispositif d'émission d'électrons
PCT/EP2019/051860 WO2019166161A1 (fr) 2018-02-27 2019-01-25 Dispositif d'émission d'électrons
EP19704225.2A EP3732702A1 (fr) 2018-02-27 2019-01-25 Dispositif d'émission d'électrons
US16/971,018 US11373835B2 (en) 2018-02-27 2019-01-25 Electron-emission device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP18158898.9A EP3531437A1 (fr) 2018-02-27 2018-02-27 Dispositif d'émission d'électrons

Publications (1)

Publication Number Publication Date
EP3531437A1 true EP3531437A1 (fr) 2019-08-28

Family

ID=61521344

Family Applications (2)

Application Number Title Priority Date Filing Date
EP18158898.9A Withdrawn EP3531437A1 (fr) 2018-02-27 2018-02-27 Dispositif d'émission d'électrons
EP19704225.2A Pending EP3732702A1 (fr) 2018-02-27 2019-01-25 Dispositif d'émission d'électrons

Family Applications After (1)

Application Number Title Priority Date Filing Date
EP19704225.2A Pending EP3732702A1 (fr) 2018-02-27 2019-01-25 Dispositif d'émission d'électrons

Country Status (3)

Country Link
US (1) US11373835B2 (fr)
EP (2) EP3531437A1 (fr)
WO (1) WO2019166161A1 (fr)

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4100297A1 (de) * 1991-01-08 1992-07-09 Philips Patentverwaltung Roentgenroehre
DE19727606A1 (de) 1997-06-28 1999-01-07 Philips Patentverwaltung Elektronenemitter mit nanokristallinem Diamant
US5857883A (en) * 1997-05-09 1999-01-12 International Business Machines Corporation Method of forming perforated metal/ferrite laminated magnet
US7751528B2 (en) 2007-07-19 2010-07-06 The University Of North Carolina Stationary x-ray digital breast tomosynthesis systems and related methods
US7817777B2 (en) 2005-12-27 2010-10-19 Siemens Aktiengesellschaft Focus detector arrangement and method for generating contrast x-ray images
US7835501B2 (en) 2006-10-13 2010-11-16 Koninklijke Philips Electronics N.V. X-ray tube, x-ray system, and method for generating x-rays
US8054944B2 (en) 2008-09-08 2011-11-08 Siemens Aktiengesellschaft Electron beam controller of an x-ray radiator with two or more electron beams
DE102010043540A1 (de) * 2010-11-08 2012-03-15 Siemens Aktiengesellschaft Röntgenröhre
US8374315B2 (en) 2009-02-03 2013-02-12 Siemens Aktiengesellschaft X-ray tube
DE102012209089A1 (de) 2012-05-30 2013-12-05 Siemens Aktiengesellschaft Röntgenröhre mit einer Drehanode

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6249569B1 (en) * 1998-12-22 2001-06-19 General Electric Company X-ray tube having increased cooling capabilities
US20040240616A1 (en) * 2003-05-30 2004-12-02 Applied Nanotechnologies, Inc. Devices and methods for producing multiple X-ray beams from multiple locations
US8189893B2 (en) * 2006-05-19 2012-05-29 The University Of North Carolina At Chapel Hill Methods, systems, and computer program products for binary multiplexing x-ray radiography
US9142381B2 (en) * 2009-06-17 2015-09-22 Koninklijke Philips N.V. X-ray tube for generating two focal spots and medical device comprising same
DE102017105546B4 (de) * 2017-03-15 2018-10-18 Yxlon International Gmbh Steckdose zur Aufnahme eines Steckers eines Hochspannungskabels für eine Mikrofokus-Röntgenröhre, Steckverbindung für ein Hochspannungskabel

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4100297A1 (de) * 1991-01-08 1992-07-09 Philips Patentverwaltung Roentgenroehre
US5857883A (en) * 1997-05-09 1999-01-12 International Business Machines Corporation Method of forming perforated metal/ferrite laminated magnet
DE19727606A1 (de) 1997-06-28 1999-01-07 Philips Patentverwaltung Elektronenemitter mit nanokristallinem Diamant
US7817777B2 (en) 2005-12-27 2010-10-19 Siemens Aktiengesellschaft Focus detector arrangement and method for generating contrast x-ray images
US7835501B2 (en) 2006-10-13 2010-11-16 Koninklijke Philips Electronics N.V. X-ray tube, x-ray system, and method for generating x-rays
US7751528B2 (en) 2007-07-19 2010-07-06 The University Of North Carolina Stationary x-ray digital breast tomosynthesis systems and related methods
US8054944B2 (en) 2008-09-08 2011-11-08 Siemens Aktiengesellschaft Electron beam controller of an x-ray radiator with two or more electron beams
US8374315B2 (en) 2009-02-03 2013-02-12 Siemens Aktiengesellschaft X-ray tube
DE102010043540A1 (de) * 2010-11-08 2012-03-15 Siemens Aktiengesellschaft Röntgenröhre
DE102012209089A1 (de) 2012-05-30 2013-12-05 Siemens Aktiengesellschaft Röntgenröhre mit einer Drehanode

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
V. BOGDAN NECULAES ET AL.: "Multisource inverse-geometry CT. Part II. X-ray source design and prototype", MEDICAL PHYSICS, vol. 43, no. 8, August 2016 (2016-08-01), pages 4617 - 4627, XP012209408, DOI: doi:10.1118/1.4954847

Also Published As

Publication number Publication date
EP3732702A1 (fr) 2020-11-04
US20210082653A1 (en) 2021-03-18
WO2019166161A1 (fr) 2019-09-06
US11373835B2 (en) 2022-06-28

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