EP0074141B1 - Générateur à rayons X pour le fonctionnement des tubes à rayons X dont la pièce centrale est mise à la masse - Google Patents

Générateur à rayons X pour le fonctionnement des tubes à rayons X dont la pièce centrale est mise à la masse Download PDF

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Publication number
EP0074141B1
EP0074141B1 EP82201068A EP82201068A EP0074141B1 EP 0074141 B1 EP0074141 B1 EP 0074141B1 EP 82201068 A EP82201068 A EP 82201068A EP 82201068 A EP82201068 A EP 82201068A EP 0074141 B1 EP0074141 B1 EP 0074141B1
Authority
EP
European Patent Office
Prior art keywords
voltage
cathode
generator
tube
ray
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
EP82201068A
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German (de)
English (en)
Other versions
EP0074141A1 (fr
Inventor
Bernd Hermeyer
Heinz Mester
Hans Negle
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 EP0074141A1 publication Critical patent/EP0074141A1/fr
Application granted granted Critical
Publication of EP0074141B1 publication Critical patent/EP0074141B1/fr
Expired legal-status Critical Current

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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
    • H05G1/26—Measuring, controlling or protecting
    • H05G1/30—Controlling
    • H05G1/32—Supply voltage of the X-ray apparatus or tube
    • 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
    • H05G1/10—Power supply arrangements for feeding the X-ray tube
    • H05G1/12—Power supply arrangements for feeding the X-ray tube with dc or rectified single-phase ac or double-phase

Definitions

  • the invention relates to an X-ray generator for operating an X-ray tube with a central part connected to ground between its anode and its cathode, the series connection of high-voltage generators which can be connected to the anode and cathode of the X-ray tube, for generating a DC voltage on the X-ray tube, and means for changing the ratio between anode voltage and cathode voltage.
  • Such an X-ray generator is known from DE-OS 29 17 636.
  • X-ray tubes An example of X-ray tubes, the X-ray generator according to the invention is intended to supply, is known from the magazine "MEDICA-MUNDI •, Vol. 25, No. 1, 1980, pages 29 and 30 and from DE-OS 28 50 583.
  • X-ray tubes of this type are also sold by Philips under the name “Super Rotalix Ceramic. They differ from the tubes commonly referred to as grid-controlled X-ray tubes in that the voltage at the metal middle part is generally positive with respect to the cathode and can assume very high values that correspond to half the maximum tube voltage - or more . In this type of tube, the anode current is smaller than the cathode current because part of the electrons - after reflection at the anode - strikes the middle part.
  • the electron current impinging on the anode is not only determined by the cathode temperature, but also essentially by the voltage between the cathode and the central part connected to ground, which leads to the fact that the current through the X-ray tube decreases as the cathode voltage decreases and the cathode temperature remains constant decreases so that full emission cannot be achieved.
  • high voltage generators with a very high internal resistance e.g. B.
  • the object of the present invention is to design an X-ray generator of the type mentioned at the outset in such a way that a high emission current is achieved with little effort, even at low tube voltages.
  • the series circuit consists of at least three high-voltage generators, that a high-voltage switching device is provided, via which one of the corresponding outputs of two interconnected high-voltage generators is connected to ground, and that the high-voltage switching device is dependent on that
  • the setting value of the tube voltage and / or tube current can be switched such that the ratio of the anode voltage to the cathode voltage is lower for small values of the tube voltage than for large values.
  • At least one of the three high-voltage generators is effective in one position of the high-voltage switching device on the cathode side and in the other position on the anode side. If it is effective on the cathode side (with relatively low cathode or tube voltages), the emission current is increased. If you leave this high voltage generator there even with large tube voltages (z. B. 150 kV), then this could lead to the cathode side, at which z. B. 100 kV would be present, would be overloaded in terms of high voltage. For this reason, this high-voltage generator must be effective on the anode side in the case of large tube voltages in which the cathode side could be overloaded by a high voltage.
  • each high voltage generator is formed by a secondary winding of a high voltage transformer, the voltage of which is rectified by a rectifier arrangement, then three secondary windings are required; however, these can at least partially be designed for a lower voltage than if only two high voltage generators were present.
  • the total number of rectifier diodes contained in the rectifier arrangements is not increased by the fact that three or more rectifier arrangements are included in the invention because the individual rectifier arrangements can at least partially be designed for lower voltages.
  • the three high-voltage generators are formed by the three secondary windings 11, 21 and 31 of a high-voltage transformer 4, the primary winding 5 of which is connected to a switching and control device (not shown in more detail), which makes it possible to generate voltages of a predetermined magnitude on the secondary windings for a predefinable period of time.
  • the secondary windings 11, 21, 31 together with a rectifier arrangement 10, 20 and 30 each form a high-voltage generator 1, 2 and 3.
  • the negative output terminal 12 of the high-voltage generator 1 is connected to the positive terminal 23 of the high-voltage generator 2, whose negative output 22 is in turn connected to the positive output 33 of the third high-voltage generator 3.
  • the positive output 13 of the high-voltage generator 1 and the negative output 32 of the high-voltage generator 3 are each connected via a damping resistor 6 to an X-ray tube 7, which has a central part 8 made of metal between the anode and cathode, connected to earth or ground.
  • the anode and cathode of the X-ray tube 7 are each connected to earth via a voltage divider 15, which is used to measure the tube voltage.
  • the temperature of the filament is determined by a heating converter 16.
  • Capacitors 17 connected between outputs 13 and 32, on the one hand, and ground, on the other hand, smooth the voltage on the X-ray tube.
  • a high-voltage switching device 9 is provided, which either connects either the negative output 22 of the high-voltage generator 2 or the negative output 12 of the high-voltage generator 1 (whose potential is identical to that of the positive output of the high-voltage generator 2) to ground.
  • the cathode voltage is generated by the high-voltage generator 3 and the anode voltage by the high-voltage generators 1 and 2 together.
  • the cathode voltage is generated together by the high-voltage generators 2 and 3, while the anode voltage is generated by the high-voltage generator 1 alone. In the latter position, the cathode voltage is as much greater than in the drawn position compared to the anode voltage.
  • the sum of the DC output voltages of the high voltage generators 1 and 2 should be equal to the DC output voltage of the high voltage generator 3. This ensures that in the drawn position of the high-voltage switching device with small tube currents (e.g. fluoroscopy) and in particular also with large tube voltages, the tube voltage is distributed symmetrically on the anode and cathode sides.
  • the ratio of the output voltages of the high voltage generator 1 and 2 must be dimensioned according to the internal resistance of the high voltage generator arrangement 1, 2 and 3. The greater this internal resistance, the greater the output voltage of the high voltage generator 2 should be compared to the output voltage of the high voltage generator 1.
  • the primary winding is connected to an inverter arrangement (as is known, for example, from DE-OS 29 08 767), there is a relatively high internal resistance.
  • the secondary windings 11 and 21 contain the same number of turns and the rectifier arrangements 10 and 20 contain the same number of rectifier diodes, so that the two high-voltage generators 1 and 2 generate the same output voltages.
  • the output voltage of the high voltage generator 3 should correspond to the sum of the output voltages of the high voltage generators 1 and 2.
  • the high-voltage generator 3 is formed with particular advantage by the series connection of two high-voltage generators identical to one another and to the high-voltage generators 1 and 2. Then four identical high-voltage generators can be used, which makes production cheaper.
  • anode voltage and cathode voltage correspond, if one disregards the polarity.
  • the cathode voltage is three times greater than the anode voltage. This could be the case with very large tube voltages, e.g. B. of 150 kV, lead to the cathode voltage being too high, so that the X-ray tube is overloaded in terms of high voltage.
  • the cathode voltage is lower than the anode voltage at high currents.
  • the reason for this effect is on the one hand the high internal resistance of the high voltage generator arrangement and on the other hand the fact that the cathode current is greater than the anode current because the electrons emerging from the cathode are partly reflected by the anode onto the central part.
  • the voltage drop on the cathode side is greater than on the anode side and the voltage distribution is asymmetrical given otherwise the same conditions (copper cross section, etc.). This can lead to the voltage at the cathode becoming so low that the desired large tube current cannot flow, particularly at low tube voltages.
  • the tube current in this case can be twice as large - possibly even greater - than the tube current at the same tube voltage and the same filament temperature in the position of the high-voltage switchover device 9 shown in the drawing.
  • the high-voltage switching device can always remain in this (not shown) switching position.
  • the high-voltage switching device is controlled by a control device 18.
  • the function of the control device 18 is to switch the high-voltage switching device into the position shown in the drawing whenever the given values of the internal resistance and the voltage of the high-voltage generator 2 and at the set values of tube voltage and tube current in the other position of the high-voltage switching device 9, the cathode voltage would be so great that the cathode side would be overloaded in terms of high voltage, which z. B. could result in their breakthrough.
  • the voltage distribution and the magnitude of the cathode voltage are almost independent of the tube current. In these cases, it is sufficient to bring the high-voltage switching device 9 into the position shown as soon as the tube voltage set by the user exceeds a predetermined value. It should be mentioned at this point that it is not possible to control the switchover directly as a function of the cathode voltage measured with the aid of the lower measuring voltage divider 15, because the switchover then takes place while the tube voltage is present, that is to say during a recording or during fluoroscopy. should be done, what should be avoided. Rather, the switchover must take place before the selected tube voltage is switched on.
  • the control device 18 contains a first changeover switch 181 which is coupled to the setting element 19 for setting the tube voltage.
  • the changeover switch 181 connects one end of one of four resistors 182, at the other end of which one of four voltages U 1 ... U 4 is connected, to a second changeover switch 183, which can be switched to one of a plurality of differently sized resistors 184 other end is connected to ground.
  • Resistors 182 should correspond to the internal resistance of the high voltage generator at the voltage selected in each case. If the internal resistance is independent of this voltage, the resistors 182 can be omitted if instead the voltages U 1 , U 2 , U 3 and U 4 , which are supplied to the first changeover switch 181, are generated by a DC voltage generator with a corresponding internal resistance.
  • the voltage on the connecting line between the two switches 181 and 183 is greater, the greater the tube voltage set and the smaller the tube current set. It depends in the same way on the set values of tube current and Tube voltage as the cathode voltage (in the position of the high-voltage switching device 9, not shown) and can therefore be used to control the high-voltage switching device 9.
  • a comparator circuit 185 is provided which compares the voltage on the connecting line of the two change-over switches 181 and 183 with a predetermined reference value U R and brings the high-voltage switchover device into the position shown when the reference value U R is exceeded and into the other Position when it falls below.
  • the control device thus represents a simulation network which simulates the electrical conditions at the cathode of the X-ray tube (in the position of the high-voltage switching device 9, not shown).
  • a simulation network which simulates the electrical conditions at the cathode of the X-ray tube (in the position of the high-voltage switching device 9, not shown).
  • the tube current of an X-ray tube can easily be measured by using a resistance through which the tube current flows, one end of which is connected to ground.
  • the tube current is the electron current that strikes the anode and generates X-rays in it.
  • the current measured in the anode line is smaller than this tube current in tubes of the type described because part of the electrons is reflected by the anode and strikes the central part 8, so that they cannot be detected in the anode current.
  • the cathode current in the X-ray tubes described here is practically the same as the tube current (the proportion of electrons that directly hits the middle part is negligible for practical purposes). Therefore, the measuring resistance must flow through the cathode current.
  • the measuring resistor 25 is connected between the two capacitors 17.
  • the high-voltage switchover device 9 contains four switch contacts 91 ... 94.
  • the switch contact 91 connects the negative output 22 of the high-voltage generator 2 either to the positive output 33 of the high-voltage generator 3 or to ground.
  • the switch contact 92 connects one end of the resistor 25 either to the positive output 23 of the high-voltage generator 2 or to the positive output 33 of the high-voltage generator 3.
  • the switch contact 93 connects the other end of the resistor 25 either to the negative output 12 of the high-voltage generator 2.
  • the switch contact 94 connects the negative output 12 of the high-voltage generator 1 either to ground or to the positive output 23 of the high-voltage generator 2. All contacts 91 to 94 are together by the control device 18, not shown, in the switch position shown in solid lines or in the dashed lines in Switchable position shown in lines switchable.
  • the current flows from the positive output 33 of the high-voltage generator 3 via the switch contact 91 to the negative output 22 of the high-voltage generator 2. From its positive output 23, the current continues to flow via the switch 92, the resistor 25 and the switch contact 93 to the negative output 12 of the high-voltage generator 1, which is connected to ground via the switch contact 94. In this position, the high voltage generators 2 and 3 together generate the cathode voltage, while the high voltage generator 1 generates the anode voltage.
  • the current flows via the contact 92 to one end of the resistor 25 to the switch contact 93 and to the negative output 22 of the high-voltage generator 2, the positive output 23 of which is connected via the switch contact 94 to the negative output 12 of the high-voltage generator 1 .
  • the negative output 22 of the high-voltage generator 2 is connected to ground via the switch contact 91, so that in this switching position the cathode voltage from the high-voltage generator 3 and the anode voltage are generated jointly by the high-voltage generators 1 and 2.
  • the effort for the high-voltage switching device is increased not only by the fact that more switch contacts are required than in the embodiment shown in FIG. 1, but also by the fact that the switch contacts must be insulated from one another in accordance with the high voltage generated by the high-voltage generator 2.
  • the potential at the switch contacts 94, 93 and 92 is more positive by the DC voltage generated by the high-voltage generator 2 than the potential at the switch contact 91.
  • the potential of the switch contact 94 is more positive by the amount mentioned than the potential of contacts 91, 92 and 93.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • X-Ray Techniques (AREA)

Claims (5)

1. Générateur à rayons X pour le fonctionnement d'un tube à rayons X présentant une partie centrale mise à la masse et prévue entre son anode et sa cathode, générateur à rayons X qui comprend un montage en série à connecter à l'anode et à la cathode du tube à rayons X comprenant des générateurs à haute tension pour fournir une tension continue aux tubes à rayons X et des moyens permettant de modifier le rapport entre la tension anodique et la tension cathodique, caractérisé en ce que le montage en série est constitué par au moins trois générateurs à haute tension (1, 2, 3), qu'un dispositif commutateur à haute tension (9) est prévu par l'intermédiaire duquel chaque fois l'une des sorties correspondantes de deux générateurs à haute tension interconnectés est mise à la masse, et que le dispositif commutateur haute tension (9) peut être commuté, suivant la valeur d'établissement de la tension de tube et/ou du courant de tube de façon que le rapport entre la tension anodique et la tension cathodique soit plus faible dans le cas de faibles valeurs de la tension de tube que dans le cas de valeurs élevées et une valeur déterminée de la tension cathodique n'est pas dépassée.
2. Générateur à rayons X selon la revendication 1, caractérisé en ce que chaque générateur à haute tension (1, 2, 3) présente un enroulement secondaire (11, 21, 31) d'un transformateur à haute tension (4), monté après un dispositif redresseur (10, 20, 30).
3. Générateur à rayons X selon l'une des revendications précédentes, caractérisé en ce que le montage en série comprend trois générateurs à haute tension (1, 2, 3) et que la sortie positive (33) du générateur à haute tension (3), dont la sortie négative (33) est connectée à la cathode du tube à rayons X, et que la sortie positive (23) du générateur à haute tension (2) connectée à ce générateur à haute tension sont couplées au dispositif de commutation à haute tension (9).
4. Générateur à rayons X selon la revendication 3, caractérisé en ce que la tension de sortie du générateur à haute tension (3), qui est connectée à la cathode, est deux fois plus élevée que la haute tension de chacun des deux autres générateurs à haute tension ; celui-ci est formé lui- même par le montage en série de deux générateurs à haute tension identiques.
5. Générateur à rayons X selon l'une des revendications 1 à 4, caractérisé par la présence d'un bipôle de résistance 25 traversé par du courant continu fourni par au moins un générateur à haute tension (3), qui est couplé au convertisseur à haute tension (91 ... 94) de façon que dans les deux positions de commutation, l'une des deux connexions du bipôle de résistance soit mise à la masse par l'intermédiaire du dispositif de commutation à haute tension (91 ... 94) (Figure 2).
EP82201068A 1981-09-04 1982-08-31 Générateur à rayons X pour le fonctionnement des tubes à rayons X dont la pièce centrale est mise à la masse Expired EP0074141B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3135061 1981-09-04
DE19813135061 DE3135061A1 (de) 1981-09-04 1981-09-04 Roentgengenerator zum betrieb von roentgenroehren mit an masse angeschlossenem mittelteil

Publications (2)

Publication Number Publication Date
EP0074141A1 EP0074141A1 (fr) 1983-03-16
EP0074141B1 true EP0074141B1 (fr) 1985-03-13

Family

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Family Applications (1)

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EP82201068A Expired EP0074141B1 (fr) 1981-09-04 1982-08-31 Générateur à rayons X pour le fonctionnement des tubes à rayons X dont la pièce centrale est mise à la masse

Country Status (5)

Country Link
US (1) US4439869A (fr)
EP (1) EP0074141B1 (fr)
JP (1) JPS5854600A (fr)
CA (1) CA1186068A (fr)
DE (2) DE3135061A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3929888A1 (de) * 1989-09-08 1991-03-14 Philips Patentverwaltung Roentgengenerator zum betrieb einer roentgenroehre mit an masse angeschlossenen roehrenteilen

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6096800U (ja) * 1983-12-07 1985-07-02 横河電機株式会社 Ｘ線管の駆動回路
DE3437064A1 (de) * 1984-10-09 1986-04-10 Siemens AG, 1000 Berlin und 8000 München Mittelfrequenz-roentgengenerator
EP0487767B1 (fr) * 1990-11-27 1993-11-18 Siemens Aktiengesellschaft Générateur de rayons X fonctionnant à haute fréquence
JP2634369B2 (ja) * 1993-07-15 1997-07-23 浜松ホトニクス株式会社 Ｘ線装置
DE19631143C2 (de) * 1996-08-01 2003-03-20 Siemens Ag Hochfrequenz-Röntgengenerator
DE19645418A1 (de) * 1996-11-04 1998-05-07 Siemens Ag Hochfrequenz-Röntgengenerator
ES2172458B1 (es) * 2001-01-10 2003-12-16 Es De Electromedicina Y Calida Transformador de alta tension.
JP2003142294A (ja) * 2001-10-31 2003-05-16 Ge Medical Systems Global Technology Co Llc 高電圧発生回路およびｘ線発生装置
US7852986B2 (en) * 2006-08-31 2010-12-14 Koninklijke Philips Electronics N.V. Power supply for an X-ray generator system

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2053606A1 (de) * 1970-10-31 1972-05-10 Mueller C H F Gmbh Einrichtung zur selbsttätigen Einstellung der Brennfleckgröße einer Röntgenröhre in Abhängigkeit von der Röhrenbelastung
DE2850583A1 (de) * 1978-11-22 1980-06-04 Philips Patentverwaltung Roentgenroehre mit zwei parallel nebeneinander angeordneten heizfaeden
DE2917636A1 (de) * 1979-05-02 1980-11-13 Philips Patentverwaltung Roentgengenerator
DE2918353A1 (de) * 1979-05-07 1980-11-20 Siemens Ag Roentgendiagnostikanlage mit mitteln zur festen vorgabe von aufnahmezeit, roentgenroehrenspannung und mas-produkt
US4334153A (en) * 1980-09-29 1982-06-08 General Electric Company X-Ray tube grid bias supply

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3929888A1 (de) * 1989-09-08 1991-03-14 Philips Patentverwaltung Roentgengenerator zum betrieb einer roentgenroehre mit an masse angeschlossenen roehrenteilen

Also Published As

Publication number Publication date
JPH0247837B2 (fr) 1990-10-23
US4439869A (en) 1984-03-27
CA1186068A (fr) 1985-04-23
JPS5854600A (ja) 1983-03-31
DE3262564D1 (en) 1985-04-18
DE3135061A1 (de) 1983-03-24
EP0074141A1 (fr) 1983-03-16

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