EP0416696B1 - X-ray apparatus - Google Patents
X-ray apparatus Download PDFInfo
- Publication number
- EP0416696B1 EP0416696B1 EP90202331A EP90202331A EP0416696B1 EP 0416696 B1 EP0416696 B1 EP 0416696B1 EP 90202331 A EP90202331 A EP 90202331A EP 90202331 A EP90202331 A EP 90202331A EP 0416696 B1 EP0416696 B1 EP 0416696B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- voltage
- cable
- ray
- ray tube
- generator
- 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 - Lifetime
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Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05G—X-RAY TECHNIQUE
- H05G1/00—X-ray apparatus involving X-ray tubes; Circuits therefor
- H05G1/08—Electrical details
Definitions
- the invention relates to an x-ray device with an x-ray emitter, a high-voltage generator for supplying the x-ray emitter with high voltage via at least one high-voltage cable, and an attenuator which is effective in the high-voltage circuit.
- a high-voltage generator for supplying the x-ray emitter with high voltage via at least one high-voltage cable
- an attenuator which is effective in the high-voltage circuit.
- Such an X-ray device is known from DE-C-393871.
- the object of the invention is to reduce the risk of damage to the X-ray tube. This object is achieved in that parallel to the output of the high-voltage generator, a series circuit effective as an attenuator is provided of a non-conductive diode during normal operation and an attenuation resistor which is in the order of magnitude of the characteristic impedance of the high-voltage cable.
- the invention is based on the finding that the X-ray tube, in the event of this fault, is the high-voltage cable abruptly short-circuits, whereby a weakly damped vibration is generated in the cable.
- a cable short-circuited at one end acts like a parallel resonant circuit.
- the cable length corresponds to a quarter of the wavelength.
- the resonance frequency results from the signal speed divided by four times the cable length.
- the cable discharges over the tube and then recharges with the opposite polarity.
- the normally blocked diode is now conductive and the cable is terminated with the resistor, which corresponds to a strongly damped resonant circuit.
- the energy of the cable is essentially converted into heat in the terminating resistor. It is advantageous if the diode is not a very fast diode, so that it can also conduct in the back half-wave.
- Fig. 1 shows an X-ray device according to the invention.
- the anode of the X-ray tube contained in the X-ray emitter 1 is grounded, while its cathode is operated at a negative high voltage of, for example, 225 kV. This is supplied by an X-ray generator 2.
- the high voltage generated in this high voltage generator in a manner not shown is generally available on a smoothing capacitor 21.
- the high-voltage generator 2 is connected to the x-ray emitter 1 via a high-voltage cable 3 with three inner conductors 31, only one of which is shown in FIG. 1 and which has practically the same high-voltage potential (the small voltage differences between these inner conductors serve the purpose Generation of a heating current in the two filaments of the cathode).
- the high-voltage cable also includes, in a known manner, an earthed wire mesh 32, preferably made of copper, which surrounds the inner conductor 31.
- the high voltage at the capacitor 21 is not fed directly to the inner conductor 31 of the high-voltage cable 3 connected to the cathode, but via an output resistor 22 of, for example, 100 kohm. This output resistance has the task of limiting the current flowing in the generator in the event of a short circuit.
- the series connection of a diode 25 and a resistor 26 is connected to the output of the high-voltage generator 2.
- the value of the resistor 26 must correspond at least in the order of magnitude to the characteristic impedance of the high-voltage cable and the diode 25 must be polarized so that it is blocked by the high voltage prevailing in normal operation.
- an oscillation results at the output of the high-voltage generator 2, in which the high voltage at the output of the high-voltage generator reverses its polarity in accordance with the natural resonance of the high-voltage cable. Whenever the polarity is reversed, the oscillating current flows through the resistor 26 and is dampened.
- the load impedance formed by the series circuit 25 and 26 is effective only in terms of radio frequency.
- This solution requires a diode (or a large number of diodes connected in series), the reverse voltage of which corresponds to the high voltage of the X-ray generator and which must be acted upon by the strong current through the X-ray tube in the event of a fault.
Landscapes
- X-Ray Techniques (AREA)
Description
Die Erfindung betrifft eine Röntgeneinrichtung mit einem Röntgenstrahler, einem Hochspannungserzeuger zur Versorgung des Röntgenstrahlers mit Hochspannung über wenigstens ein Hochspannungskabel, und einem im Hochspannungskreis wirksamen Dämpfungsglied. Eine derartige Röntgeneinrichtungen ist aus DE-C-393871 bekannt.The invention relates to an x-ray device with an x-ray emitter, a high-voltage generator for supplying the x-ray emitter with high voltage via at least one high-voltage cable, and an attenuator which is effective in the high-voltage circuit. Such an X-ray device is known from DE-C-393871.
In der Praxis lassen sich Störungen der Röntgenröhre nicht ganz vermeiden. Bei diesen Störungen entstehen im Innern der Röntgenröhre Ladungsträgerlawinen, die zu einem Durchzünden der Röntgenröhre führen, wobei sich die in den Kapazitäten des Hochspannungskabels gespeicherte Energie stoßartig über die Röntgenröhre entlädt. Der Röhrenstrom kann dabei zeitweilig Werte im Bereich von kA erreichen, so daß die Gefahr der Schädigung der Röntgenröhre besteht. Diese Gefahr ist umso ausgeprägter, je länger das Hochspannungskabel ist bzw. - bei zwei Hochspannungskabeln zwischen Hochspannungserzeuger und Röntgenstrahler - die Hochspannungskabel und je höher die Betriebsspannung der Röntgenröhre ist.In practice, disorders of the X-ray tube cannot be completely avoided. In the case of these disturbances, charge avalanches arise in the interior of the X-ray tube, which lead to the X-ray tube igniting, the energy stored in the capacitances of the high-voltage cable being discharged suddenly via the X-ray tube. The tube current can temporarily reach values in the range of kA, so that there is a risk of damage to the X-ray tube. This risk is all the more pronounced the longer the high-voltage cable is or - in the case of two high-voltage cables between the high-voltage generator and the X-ray source - the high-voltage cable and the higher the operating voltage of the X-ray tube.
Aufgabe der Erfindung ist es, die Gefahr der Schädigung der Röntgenröhre zu verringern. Diese Aufgabe wird erfindungsgemäß dadurch gelöst, daß parallel zum Ausgang des Hochspannungserzeugers eine als Dämpfungsglied wirksame Serienschaltung einer im Normalbetrieb nichtleitenden Diode und eines Dämpfungswiderstandes vorgesehen ist, der in der Größenordnung des Wellenwiderstandes des Hochspannungskabels liegt.The object of the invention is to reduce the risk of damage to the X-ray tube. This object is achieved in that parallel to the output of the high-voltage generator, a series circuit effective as an attenuator is provided of a non-conductive diode during normal operation and an attenuation resistor which is in the order of magnitude of the characteristic impedance of the high-voltage cable.
Die Erfindung basiert auf der Erkenntnis, daß die Röntgenröhre im Falle dieser Störung das Hochspannungskabel schlagartig kurzschließt, wodurch in dem Kabel eine nur schwach gedämpfte Schwingung erzeugt wird. Ein an einem Ende kurzgeschlossenes Kabel wirkt wie ein Parallelschwingkreis. Die Kabellänge entspricht dabei einem Viertel der Wellenlänge. Die Resonanzfrequenz ergibt sich aus der Signalgeschwindigkeit geteilt durch die vierfache Kabellänge.The invention is based on the finding that the X-ray tube, in the event of this fault, is the high-voltage cable abruptly short-circuits, whereby a weakly damped vibration is generated in the cable. A cable short-circuited at one end acts like a parallel resonant circuit. The cable length corresponds to a quarter of the wavelength. The resonance frequency results from the signal speed divided by four times the cable length.
Nach einem Kurzschluß in der Röntgenröhre entlädt sich das Kabel über die Röhre und lädt sich danach mit umgekehrter Polarität wieder auf. Die im Normalzustand gesperrte Diode wird jetzt leitend und das Kabel ist mit dem Widerstand abgeschlossen, was einem stark gedämpften Schwingkreis entspricht. Die Energie des Kabels wird im wesentlichen im Abschlußwiderstand in Wärme umgesetzt. Es ist von Vorteil, wenn die Diode keine sehr schnelle Diode ist, so daß sie auch noch in der Rückhalbwelle leiten kann.After a short circuit in the X-ray tube, the cable discharges over the tube and then recharges with the opposite polarity. The normally blocked diode is now conductive and the cable is terminated with the resistor, which corresponds to a strongly damped resonant circuit. The energy of the cable is essentially converted into heat in the terminating resistor. It is advantageous if the diode is not a very fast diode, so that it can also conduct in the back half-wave.
Die Erfindung wird nachstehend anhand der Zeichnung näher erläutert.The invention is explained below with reference to the drawing.
Fig. 1 zeigt eine Röntgeneinrichtung nach der Erfindung.Fig. 1 shows an X-ray device according to the invention.
Die Anode der im Röntgenstrahler 1 enthaltenen Röntgenröhre ist geerdet, während ihre Kathode an einer negativen Hochspannung von z.B. 225 kV betrieben wird. Diese wird von einem Röntgengenerator 2 geliefert. Die in diesem Hochspannungsgenerator auf nicht näher dargestellte Weise erzeugte Hochspannung ist im allgemeinen an einem Glättungskondensator 21 verfügbar. Der Hochspannungserzeuger 2 ist mit dem Röntgenstrahler 1 über ein Hochspannungskabel 3 mit drei Innenleitern 31 verbunden, von denen in Fig. 1 nur einer dargestellt ist und die praktisch das gleiche Hochspannungspotential führen (die geringen Spannungsunterschiede zwischen diesen Innenleitern dienen der Erzeugung eines Heizstroms in den beiden Heizfäden der Kathode). Das Hochspannungskabel umfaßt darüberhinaus in bekannter Weise ein geerdetes Drahtgeflecht 32, vorzugsweise aus Kupfer, das die Innenleiter 31 umschließt. Die Hochspannung am Kondensator 21 wird dem mit der Kathode verbundenen Innenleiter 31 des Hochspannungskabels 3 nicht direkt zugeführt, sondern über einen Ausgangswiderstand 22 von z.B. 100 kohm. Dieser Ausgangswiderstand hat die Aufgabe, den im Falle eines Kurzschlusses im Generator fließenden Strom zu begrenzen.The anode of the X-ray tube contained in the X-ray emitter 1 is grounded, while its cathode is operated at a negative high voltage of, for example, 225 kV. This is supplied by an X-ray generator 2. The high voltage generated in this high voltage generator in a manner not shown is generally available on a
Im Falle einer Störung in der Röntgenröhre bildet diese für das Hochspannungskabel praktisch einen Kurzschluß, wobei sich die Kabelkapazitäten über die Röntgenröhre - mit Entladungsströmen im kA-Bereich - entladen. Wegen der Kabelinduktivitäten ergibt sich dabei eine Schwingung, deren Spannungsmaximum am Ausgang des Hochspannungserzeugers liegt. Diese Schwingung wird gedämpft, um ihre Energie und damit auch die Gefahr einer Beschädigung des Röntgenstrahlers 1 zu verringern.In the event of a malfunction in the X-ray tube, this practically forms a short circuit for the high-voltage cable, the cable capacitances discharging via the X-ray tube - with discharge currents in the kA range. Because of the cable inductance, there is an oscillation, the voltage maximum of which lies at the output of the high-voltage generator. This vibration is damped in order to reduce its energy and thus also the risk of damage to the X-ray emitter 1.
Zur Dämpfung der Schwingung des Hochspannungskabels ist an den Ausgang des Hochspannungserzeugers 2 die Serienschaltung einer Diode 25 und eines Widerstandes 26 angeschlossen. Der Wert des Widerstandes 26 muß zumindest größenordnungsmäßig dem Wellenwiderstand des Hochspannungskabels entsprechen und die Diode 25 muß so gepolt sein, daß sie durch die im Normalbetrieb herrschende Hochspannung gesperrt wird. Im Falle einer Störung der Röntgenröhre ergibt sich am Ausgang des Hochspannungserzeugers 2 eine Schwingung, bei der die Hochspannung am Ausgang des Hochspannungserzeugers ihre Polarität entsprechend der Eigenresonanz des Hochspannungkabels umkehrt. Immer dann, wenn die Polarität umgekehrt ist, fließt der Schwingungsstrom über den Widerstand 26 und wird dadurch gedämpft. Somit ist die durch die Serienschaltung 25 und 26 gebildete Belastungsimpedanz nur hochfrequenzmäßig wirksam. Diese Lösung erfordert eine Diode (bzw. eine Vielzahl in Serie geschalteter Dioden), deren Sperrspannung der Hochspannung des Röntgengenerators entspricht und die im Störfall von dem starken Strom durch die Röntgenröhre beaufschlagbar sein muß.To dampen the vibration of the high-voltage cable, the series connection of a
Claims (1)
- An X-ray device, comprising an X-ray source (1), a high-voltage generator (2) for supplying the X-ray source with a high voltage via at least one high-voltage cable, and a damping member which is active in the high-voltage circuit, characterized in that parallel to the output of the high-voltage generator (2) there is connected a damping member in the form of a series connection of a diode (25) which is not conductive during normal operation and a damping resistor (26) whose resistance is of the order of magnitude of the characteristic impedance of the high-voltage cable.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE3929402 | 1989-09-05 | ||
DE3929402A DE3929402A1 (en) | 1989-09-05 | 1989-09-05 | X-RAY DEVICE |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0416696A2 EP0416696A2 (en) | 1991-03-13 |
EP0416696A3 EP0416696A3 (en) | 1991-08-14 |
EP0416696B1 true EP0416696B1 (en) | 1993-08-25 |
Family
ID=6388637
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP90202331A Expired - Lifetime EP0416696B1 (en) | 1989-09-05 | 1990-09-03 | X-ray apparatus |
Country Status (4)
Country | Link |
---|---|
US (1) | US5093853A (en) |
EP (1) | EP0416696B1 (en) |
JP (1) | JPH0398298A (en) |
DE (2) | DE3929402A1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE19536247A1 (en) * | 1995-09-28 | 1997-04-03 | Siemens Ag | X=ray tube with rotary anode |
DE19500733B4 (en) * | 1994-01-31 | 2006-08-17 | Siemens Ag | X-ray emitter arrangement |
Families Citing this family (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5008912A (en) * | 1989-10-05 | 1991-04-16 | General Electric Company | X-ray tube high voltage cable transient suppression |
US5159697A (en) * | 1990-12-18 | 1992-10-27 | General Electric Company | X-ray tube transient noise suppression system |
US5132999A (en) * | 1991-01-30 | 1992-07-21 | General Electric Company | Inductive x-ray tube high voltage transient suppression |
DE4138889A1 (en) * | 1991-01-30 | 1992-08-13 | Felten & Guilleaume Energie | X-RAY MANAGEMENT |
DE4201616A1 (en) * | 1992-01-22 | 1993-07-29 | Philips Patentverwaltung | X=ray device - has damping arrangement contained in high voltage cables, heat converter in tube protection housing |
US6738275B1 (en) * | 1999-11-10 | 2004-05-18 | Electromed Internationale Ltee. | High-voltage x-ray generator |
US7081436B2 (en) | 2001-01-26 | 2006-07-25 | General Electric Company | Paste formulation for seed treatment of plants |
DE10300542A1 (en) * | 2003-01-09 | 2004-07-22 | Siemens Ag | High voltage supply for an X-ray device |
CA2698635A1 (en) | 2007-09-14 | 2009-03-19 | E.I. Du Pont De Nemours & Company | Liquid seed dressing method for dressing small quantities of seed |
DE102014015974B4 (en) | 2014-10-31 | 2021-11-11 | Baker Hughes Digital Solutions Gmbh | Connection cable for reducing flashover-induced transient electrical signals between the acceleration section of an X-ray tube and a high-voltage source |
Family Cites Families (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE393871C (en) * | 1921-08-09 | 1924-04-16 | C H F Mueller Spezialfabrik Fu | Device for damping overvoltage waves in X-ray systems with resistors connected to the supply line |
US2976462A (en) * | 1956-11-13 | 1961-03-21 | Sanborn Company | Protective system |
NL7703425A (en) * | 1977-03-30 | 1978-10-03 | Philips Nv | DEVICE WITH A TRANSFORMER FOR JUMP-SHAPED CHANGING VOLTAGES. |
NL7703493A (en) * | 1977-03-31 | 1978-10-03 | Philips Nv | DEVICE WITH A HIGH-VOLTAGE ELECTRONIC TUBE. |
DE2917636A1 (en) * | 1979-05-02 | 1980-11-13 | Philips Patentverwaltung | X-RAY GENERATOR |
JPS614198A (en) * | 1984-06-18 | 1986-01-10 | Hitachi Ltd | X-ray device |
JPS62278798A (en) * | 1986-05-27 | 1987-12-03 | Toshiba Corp | X-ray generator |
DE3639088A1 (en) * | 1986-11-14 | 1988-05-26 | Siemens Ag | CIRCUIT ARRANGEMENT WITH A PROTECTIVE RESISTOR FOR CURRENT LIMITATION IN X-RAY EMISSIONERS |
DE8807359U1 (en) * | 1988-06-06 | 1989-10-12 | Siemens AG, 1000 Berlin und 8000 München | X-ray tubes |
US5008912A (en) * | 1989-10-05 | 1991-04-16 | General Electric Company | X-ray tube high voltage cable transient suppression |
-
1989
- 1989-09-05 DE DE3929402A patent/DE3929402A1/en not_active Withdrawn
-
1990
- 1990-08-31 JP JP2232314A patent/JPH0398298A/en active Pending
- 1990-09-03 EP EP90202331A patent/EP0416696B1/en not_active Expired - Lifetime
- 1990-09-03 DE DE90202331T patent/DE59002462D1/en not_active Expired - Fee Related
- 1990-09-05 US US07/578,047 patent/US5093853A/en not_active Expired - Fee Related
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE19500733B4 (en) * | 1994-01-31 | 2006-08-17 | Siemens Ag | X-ray emitter arrangement |
DE19536247A1 (en) * | 1995-09-28 | 1997-04-03 | Siemens Ag | X=ray tube with rotary anode |
DE19536247C2 (en) * | 1995-09-28 | 1999-02-04 | Siemens Ag | X-ray tube |
Also Published As
Publication number | Publication date |
---|---|
EP0416696A3 (en) | 1991-08-14 |
EP0416696A2 (en) | 1991-03-13 |
US5093853A (en) | 1992-03-03 |
JPH0398298A (en) | 1991-04-23 |
DE3929402A1 (en) | 1991-03-07 |
DE59002462D1 (en) | 1993-09-30 |
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