EP0405399B1 - Apparat zur Erzeugung von Röntgenstrahlen - Google Patents

Apparat zur Erzeugung von Röntgenstrahlen Download PDF

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Publication number
EP0405399B1
EP0405399B1 EP19900112038 EP90112038A EP0405399B1 EP 0405399 B1 EP0405399 B1 EP 0405399B1 EP 19900112038 EP19900112038 EP 19900112038 EP 90112038 A EP90112038 A EP 90112038A EP 0405399 B1 EP0405399 B1 EP 0405399B1
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EP
European Patent Office
Prior art keywords
frequency
voltage
transformer
high voltage
frequency converting
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
Application number
EP19900112038
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English (en)
French (fr)
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EP0405399A3 (en
EP0405399A2 (de
Inventor
Toyoshige C/O Intell. Property Division Harada
Kenichi C/O Intell. Property Division Tanbo
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Toshiba Corp
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Toshiba Corp
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Filing date
Publication date
Priority claimed from JP2150458A external-priority patent/JPH0395898A/ja
Application filed by Toshiba Corp filed Critical Toshiba Corp
Publication of EP0405399A2 publication Critical patent/EP0405399A2/de
Publication of EP0405399A3 publication Critical patent/EP0405399A3/en
Application granted granted Critical
Publication of EP0405399B1 publication Critical patent/EP0405399B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • 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
    • 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
    • H05G1/20—Power supply arrangements for feeding the X-ray tube with high-frequency ac; with pulse trains

Definitions

  • the present invention relates to an X-ray generator apparatus having an X-ray tube which generates X-rays when applied with a high voltage obtained by increasing an input A.C. voltage by means of a step-up transformer or the like and rectifying the increased voltage.
  • a frequency converter 2 for converting the frequency of a voltage supplied from an input power source is connected to the primary side of a high voltage transformer 3.
  • An output voltage of the frequency converter 2 is increased by the high voltage transformer 3 and an output voltage of the high voltage transformer 3 is rectified by a high voltage rectifier 4.
  • a rectified output of the high voltage rectifier 4 is applied between the anode and cathode of an X-ray tube 5 serving as an X-ray source.
  • the frequency converter 2 is generally formed of a rectifier for converting an input A.C. voltage to a D.C. voltage, a capacitor for filtering the D.C. voltage, and an inverter for converting the D.C. voltage from the capacitor to an A.C. voltage of a desired frequency.
  • the frequency converter 2 converts the frequency fo (which is a commercial frequency and is generally 50/60 Hz) of the input A.C. voltage to a frequency fl which is higher than the frequency fo and then applies the voltage to the high voltage transformer 3.
  • the output frequency fl of the frequency converter 2 is set to be higher, the size and weight of the frequency converter 2 and high voltage transformer 3 can be reduced.
  • the capacitance and inductance can be reduced as the frequency is set higher if the impedances are kept unchanged. Since the capacitance and inductance vary in proportion to the size of the capacitor and coil, the size and weight of the frequency converter 2 and high voltage transformer 3 using the coil and capacitor can be reduced as the frequency becomes higher.
  • Fig. 2 shows an equivalent circuit of the device shown in Fig. 1 in view of the secondary portion of the transformer 3.
  • L1, L2 and M respectively denote the primary inductance, secondary inductance and mutual inductance of the high voltage transformer 3.
  • N denotes the turn ratio (the number of turns of the secondary windings/the number of turns of the primary windings) of the transformer 3.
  • the high voltage transformer 3 in order to obtain a high output voltage, is so designed that the number of turns of the secondary winding is set to be very larger than that of the primary winding, and thus the secondary inductance L2 is very larger than the primary inductance L1 and mutual inductance M. Therefore, the inductance of the secondary portion of the high voltage transformer 3 which is actually equal to (L2 - M) as shown in Fig. 2 can be regarded as being equal to the secondary inductance L2 by neglecting M, and in the following explanation, it is assumed that the inductance of the secondary portion is equal to L2.
  • the impedance Z2 becomes higher as the output frequency fl of the frequency converter 2 becomes higher, causing a problem that the voltage Ex applied to the X-ray tube 5 is lowered.
  • the output frequency fl of the conventional frequency converter 2 has an upper limit of approximately 10 KHz and a higher frequency exceeding the upper limit cannot be attained. If the frequency is set to approximately 10 KHz, it is difficult to greatly reduce the size and weight of the transformer and rectifier circuit and noise may be generated from the transformer 3. The reason why the output frequency fl of the frequency converter 2 can be increased only to approximately 10 KHz at most is that the secondary inductance L2 of the high voltage transformer 3 is very large.
  • a capacitor C1 is serially connected to the primary winding of the high voltage transformer 3 to attain a series resonance operation on the primary portion.
  • a capacitor C2 is connected in parallel with the primary winding of the high voltage transformer 3 to attain a parallel resonance operation on the primary portion.
  • a voltage on the primary portion of the high voltage transformer 3 is equivalently increased by the series resonance or parallel resonance operation.
  • the inductance L1 of the primary portion is originally small and the resonance voltage is low, and therefore, in order to obtain the same voltage applied to X-ray tube 5 as that obtained in a case wherein no resonance circuit is connected, it is only possible to increase the output frequency of the frequency converter 2 to two or three times the output frequency set in a case wherein no resonance circuit is connected.
  • the secondary winding of the high voltage transformer is divided into a plurality of sub-windings to increase the frequency of the high voltage transformer, the sub-windings are connected to rectifier circuits are serially coupled and applied to an X-ray tube.
  • the high voltage transformer is not divided and the high voltage transformer can be regarded as being a single transformer, and an output of one frequency converter is simply connected to a single high voltage transformer. Therefore, like the conventional case shown in Fig. 1, it is only possible to increase the frequency to approximately 10 KHz at most.
  • EP-A-0 286 678 discloses an X-ray tomograph, which does not require any particular insulation mechanism for a slip ring that works to supply electric power to an X-ray tube and which does not cause any increase in the weight of the rotary part.
  • a voltage of a commercial power source is inverted by an inverter into an A.C. voltage of a value midway between the voltage of the commercial power source and a high voltage to be supplied to the X-ray tube and of a frequency of 200 Hz to 2 KHz.
  • the A.C. voltage thus inverted is transferred via a slip ring to the rotary part where the A.C. voltage is boosted through step-up tanks which comprise light weight transformers rectifiers and smoothing circuits.
  • the step-up tank means may consist of a plurality of a step-up circuits for producing high D.C. voltages. In this case the sum of these D.C. voltages is applied to the X-ray tube.
  • An object of the present invention is to provide an X-ray generator apparatus in which the frequency of a voltage from an A.C. power source is increased by a frequency converter, then the voltage is increased by means of a transformer, and the increased voltage rectified by means of a rectifier and applied to an X-ray tube, and in which the secondary inductance (L2) of the transformer can be reduced and as a result the upper limit of the output frequency of the frequency converter can be increased. Therefore the size and weight of the transformer and rectifier can be reduced.
  • An X-ray generator apparatus comprises the features of claim 1.
  • Advantageous embodiments of the invention are defined by the subclaims.
  • FIG. 5 is a block diagram showing the construction of an X-ray generator apparatus.
  • An A.C. power source 11 serving as an input power source is connected to the input terminal of an frequency converter 12.
  • the frequency converter 12 increases the frequency of an A.C. voltage supplied from the A.C. power source 11.
  • High voltage transformers 131, 132, ... 13 n are connected in parallel with one another between output terminals of the frequency converter 12. That is, one end of the primary winding of each of the high voltage transformers 131, 132, ...
  • 13 n is connected to one of the output terminals of the frequency converter 12 and the other end of the primary winding of each of the high voltage transformers 131, 132, ... 13 n is connected to the other output terminal of the frequency converter 12.
  • the secondary windings of the high voltage transformers 131, 132, ... 13 n are respectively connected to high voltage rectifiers 141, 142, ... 14 n .
  • the output terminals of the high voltage rectifiers 141, 142, ... 14 n are serially connected and the result of serial addition obtained by the series connection is applied to an X-ray tube 15.
  • the positive output terminals of the high voltage rectifiers 141 is connected to the anode of the X-ray tube 15
  • the negative output terminals of the high voltage rectifiers 141, 142, ... 14 n-1 are connected to the positive output terminals of the high voltage rectifiers 142, 143, ... 14 n
  • the negative output terminal of the high voltage rectifier 14 n is connected to the cathode of the X-ray tube 15.
  • the number of turns of each of the primary windings of the high voltage transformers 131, 132, ... 13 n is set to be equal to that of the primary winding of the conventional high voltage transformer 3 shown in Fig. 1 and the number of turns of each of the secondary windings of the high voltage transformers 131, 132, ... 13 n is set to 1/n of that of the secondary winding of the conventional high voltage transformer 3 in order to simplify the description.
  • Fig. 6A is an equivalent circuit diagram of a secondary portion (a portion from the secondary winding to the X-ray tube with the rectifier being neglected) of the conventional transformer 3 of Fig. 1.
  • Fig. 6B is also the equivalent circuit diagram of the secondary portions of the transformers 131, 132, ... 13 n of the apparatus shown in Fig. 5.
  • the number of turns of the secondary winding of each of the high voltage transformers 3, 131, 132, ... 13 n is extremely larger than that of the primary winding thereof, and the secondary inductance L2 is set to a large value. Therefore, the equivalent circuit diagrams can be expressed only by the secondary inductance L2 as shown in Figs. 6A and 6B.
  • the frequency converter is generally on/off operated by the switching pulse and outputs a pulse signal. Therefore, the voltage E2 is also expressed by a pulse.
  • the number of turns of the secondary winding of each of the high voltage transformers 131, 132, ... 13 n is set to 1/n of that of the high voltage transformer 3 in the conventional device (Fig. 1). Since the inductance of a coil varies in proportion to the square of the number of turns, the secondary inductance becomes L2/n2 and the secondary voltage becomes E2/n in each of the high voltage transformers 131, 132, ... 13 n . Further, the load of each of the high voltage transformers 131, 132, ... 13 n is substantially the same as a value obtained by dividing the load Rx in the conventional device by n, that is, it becomes Rx/n. As a result, the equivalent circuit diagram of the apparatus of Fig. 5 can be expressed as shown in Fig. 6B.
  • the time constant in the device of this embodiment (Fig. 5) is set to 1/n of that of the conventional device (Fig. 1), and therefore, it is understood that the frequency of the transformers 131, 132, ... 13 n can be increased by n times since the same voltage is obtained if the pulse width of the output of the frequency converter 12 is set to ⁇ b.
  • the high voltage transformer is divided into a plurality (for example, n) of transformers 131, 132, ... 13 n having a small capacity (the number of turns of the primary winding is kept unchanged and the number of turns of the secondary winding is reduced to 1/n times the original value), the primary windings of the divided transformers 131, 132, ... 13 n are connected in parallel with one another between the output terminals of the frequency converter 12 and a voltage obtained by serially adding together the rectification results of the outputs of the respective transformers is applied to the X-ray tube 15.
  • the apparatus including the frequency converter 12 can be made small and lightweight. Since the output frequency of the frequency converter 12 can be increased up to approximately 100 KHz or to a frequency which exceeds the audio frequency, generation of noise which is a problem in the conventional device can be prevented. Further, since the output control of the frequency converter 12 can be effected at a higher speed as the output frequency thereof increases, a high voltage applied to the X-ray tube 15 can be more precisely set by using the feedback operation. Further, since high voltage wave ripples become smaller as the frequency becomes higher, a flat high voltage wave can be obtained.
  • the rising characteristic of the tube voltage can be improved as shown by the curve B of Fig. 7, it becomes easy to apply a high voltage in a pulse form to the X-ray tube 15 and generate X-rays only at necessary timings, thereby making it possible to reduce the amount of X-ray radiation to an object.
  • the frequency converter can change the output voltage in addition to the output frequency by means of a pulse width modulation (PWM) for changing the pulse width of the switching pulse.
  • PWM pulse width modulation
  • the high voltage transformer and high voltage rectifier are disposed in a container filled with insulating oil. Since the container is substantially entirely filled with insulating oil, the volume and weight thereof become very large. In this case, the maintenance therefor is troublesome and there occurs a problem that oil leaks out of the container and stains the surrounding.
  • the transformer since the transformer is divided into a plurality of transformers of small capacities the high voltage transformer and high voltage rectifier are disposed in a container of small capacity and can be molded into one unit with solid insulation material including gel insulating material.
  • Each molding unit may be constructed by a single transformer 131 and a single rectifier 141 as shown in Fig. 8 or by a plurality of transformers 131 to 13 i and a plurality of rectifiers 141 and 14 i as shown in Fig. 9. Further, as shown in Fig. 10, only the secondary winding of the transformer 131 and the rectifier 141 are molded and it is not always necessary to mold the primary winding of the transformer. Although not shown in the drawing, the high voltage transformer and the rectifier may be separately molded and they are connected by connectors or cables. Thus, various combinations of the molds can be selectively made.
  • Fig. 11 is a block diagram of the second embodiment. Portions which are the same as those of the apparatus of Fig. 5 are denoted by the same reference numerals and the detail description thereof is omitted.
  • Inverters 121, 122 ... 12 n which are connected in parallel with one another are connected to the A.C. power source 11.
  • Outputs of the frequency converters 121, 122, ... 12 n are supplied to rectifiers 141, 142, ... 14 n via high voltage transformers 131 132, ... 13 n .
  • Capacitors C R are respectively connected in series with the secondary windings of the high voltage transformers 131, 132, ... 13 n to constitute series resonant circuits on the secondary portion of the transformers.
  • the same effect as that of the apparatus of Fig. 5 can be obtained.
  • the tube voltage can be roughly controlled by controlling the number of frequency converters which are set in the rest state.
  • the frequency converters are PWM-controlled, the tube voltage can be precisely controlled.
  • the defective frequency converters are set into the rest state and other frequency converters which are otherwise set in the rest or nonoperative state can be used instead of the defective frequency converters. Therefore, it becomes possible to prevent the whole X-ray generator apparatus from being set into the inoperative state.
  • the maximum output is lowered by an amount corresponding to the number of defective frequency converters, but it is seldom to use the maximum output and the device can be used without receiving practical interference while the defective frequency converter is being replaced.
  • the resonance capacitor C R is connected to the secondary winding of each of the high voltage transformers 131, 132, ... 13 n to cause an LC series resonance so as to prevent the voltage applied to the X-ray tube 15 from being lowered and to further increase the frequency of the frequency converters.
  • E2 and L2 in the respective resonant circuits can be reduced to E2 / n and L2 / n2 as shown in Fig. 6B as in the apparatus of Fig. 5.
  • L2 varies inversely with the square of the dividing number n, it becomes extremely small. In this way, since the voltages E L and E C across L2 and C R can be suppressed to small values, the advantage of the resonance on the secondary portion of the transformer can be effectively used.
  • the secondary inductance L2 becomes smaller, making it possible to attain a high frequency operation.
  • influence by the secondary inductance L2 can be completely neglected, making it possible to attain a higher frequency operation.
  • the dividing number can be reduced within the permissible range of the breakdown voltage of the transformer and the capacitor.
  • the secondary resonance is not limited to the series resonance described above but may be a parallel resonance attained by connecting a capacitor in parallel with the secondary winding of the high voltage transformer.
  • Fig. 13 shows the characteristic of the voltage applied to the X-ray tube 15 obtained when the secondary portion is set in the resonant mode.
  • solid lines indicate Ex, and curves A and B among them respectively indicate the case of the conventional device and the case wherein the transformer is divided into n portions like the curves A and B of Fig. 7, and a curve D indicates a characteristic obtained when the high voltage transformer is divided and the secondary portion is set in the resonant mode.
  • the raising characteristic of the curves A and B which is suppressed by the secondary inductance of the transformer is improved by means of the resonance as indicated by the curve D. Therefore, a higher frequency operation can be attained, and the voltage applied to the X-ray tube can be further increased.
  • Fig. 13 fr indicates the resonant frequency.
  • broken line curves indicate the voltages obtained by multiplying the terminal voltages E L and E C of the secondary inductance L2 and the capacitor C R with the dividing number n.
  • the operation frequency can be further enhanced and the dividing number can be reduced by use of the secondary resonance in comparison with a case wherein the high voltage transformer is simply divided.
  • the transformers and rectifiers can be selectively molded into respective units with solid insulation material. It is not necessary to respectively connect the transformers to the frequency converters. It is possible to connect several transformers to a single frequency converter.
  • the output frequency of the frequency converter can be increased by dividing the transformer for increasing an output A.C. voltage of the frequency converter which increases the frequency of an A.C. voltage into a plurality of transformers of small capacity in which the number of turns of the secondary winding is smaller than that of the original transformer, adding outputs of the transformers together, and applying the result of addition to the X-ray tube.
  • the apparatus can be made small and lightweight, the control speed of the voltage can be enhanced if the frequency is increased, and the output voltage can be precisely controlled by feeding back the output.
  • the assembling and maintenance can be simplified by molding the divided transformers and the rectifiers into respective units with solid insulating material (including gel insulating material).
  • ripple components included in the output voltage can be easily suppressed and stabilized by the high frequency operation and the X-rays can be easily generated in a pulse form.
  • the frequency is increased, the frequency of the switching pulse of the frequency so that noise can be prevented from being generated.
  • each frequency converter can be easily and independently controlled so that the precision of generation of the X-rays can be enhanced, and even if one or some frequency converters become defective, the apparatus can be continuously operated by using the remaining frequency converters.
  • the frequency is further increased by connecting the capacitor to the secondary winding of the transformer to form an LC resonance circuit and effect the resonance operation.

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  • X-Ray Techniques (AREA)

Claims (8)

  1. Apparat zum Erzeugen von Röntgenstrahlen, der mit einer Wechselspannungsquelle verbunden ist und zum Anlegen einer Gleichspannung an eine Röntgenröhre dient, mit
       einer Frequenzkonvertereinrichtung (12), die mit der Wechselspannungsquelle verbunden ist, zum Empfangen einer Wechselspannung aus der Wechselspannungsquelle und zum Erhöhen der Frequenz der Eingangswechselspannung;
       einer Vielzahl von Transformatoreinrichtungen (13₁, 13₂, ... 13n), die parallel mit einem Ausgang der Frequenzkonvertereinrichtung (12) verbunden sind, zum Empfangen der Ausgangsspannung der Frequenzkonvertereinrichtung (12) und zum Erhöhen der Eingangsspannung; und
       Gleichrichtereinrichtungen (14₁, 14₂, ... 14n), die die Ausgangssignale der Vielzahl von Transformatoreinrichtungen (13₁, 13₂, ... 13n) gleichrichten und eine der Summe der Ausgangssignale der Transformatoreinrichtungen entsprechende Gleichspannung an die Röntgenröhre anlegen,
       dadurch gekennzeichnet, daß
       die Vielzahl von Transformatoreinrichtungen jeweils Resonanzkondensatoren (CR) aufweist, die jeweils mit einer Sekundärwicklung einer entsprechenden Transformatoreinrichtung verbunden sind.
  2. Apparat nach Anspruch 1, dadurch gekennzeichnet, daß
       die Frequenzkonvertereinrichtung eine Vielzahl von parallel mit der Wechselspannungsquelle verbundenen Frequenzkonvertereinrichtungen (12₁, 12₂, ... 12n) umfaßt, zum Empfangen einer Wechselspannung aus der Wechselspannungsquelle und zum Erhöhen der Frequenz der Eingangswechselspannung, und
       die Vielzahl von Transformatoreinrichtungen (13₁, 13₂, ... 13n) mit den Ausgängen der Vielzahl von Frequenzkonvertereinrichtungen (12₁, 12₂, ... 12n) verbunden ist.
  3. Apparat nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die Gleichrichtereinrichtung eine Vielzahl von Gleichrichtern (14₁, 14₂, ... 14n) aufweist, die jeweils mit Ausgangsanschlüssen der Vielzahl von Transformatoreinrichtungen (13₁, 13₂, ... 13n) verbunden sind.
  4. Apparat nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß
       mindestens eine Sekundärwicklung der Vielzahl von Transformatoreinrichtungen und die Gleichrichtereinrichtung in festes oder Gel-Isoliermaterial eingeformt sind.
  5. Apparat nach Anspruch 3, dadurch gekennzeichnet, daß
       Kombinationen von mindestens Sekundärwicklungen der Vielzahl von Transformatoreinrichtungen und der Vielzahl von Gleichrichtern einzeln oder in vorbestimmter Anzahl gleichzeitig in festes oder Gel-Isoliermaterial eingeformt sind.
  6. Apparat nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, daß
       jede der Vielzahl von Transformatoreinrichtungen eine Primärwicklung, eine Sekundärwicklung und Kerne aufweist, auf welche die Primär- und die Sekundärwicklung gewickelt sind, wobei die Kerne aus Ferrit gebildet sind.
  7. Apparat nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, daß
       die Frequenzkonvertereinrichtung Mittel zum Steuern der Impulsbreite oder des Impulsintervalls von an einen Schalttransistor angelegten Schaltimpulsen aufweist, zum Steuern der Ausgangsspannung der Frequenzkonvertereinrichtung, wobei der Schalttransistor in der Frequenzkonvertereinrichtung enthalten ist.
  8. Apparat nach Anspruch 2, dadurch gekennzeichnet, daß
       die Vielzahl von Transformatoreinrichtungen jeweils mit der Vielzahl von Frequenzkonvertereinrichtungen verbunden ist.
EP19900112038 1989-06-30 1990-06-25 Apparat zur Erzeugung von Röntgenstrahlen Expired - Lifetime EP0405399B1 (de)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP169645/89 1989-06-30
JP16964589 1989-06-30
JP150458/90 1990-06-08
JP2150458A JPH0395898A (ja) 1989-06-30 1990-06-08 Ｘ線発生装置

Publications (3)

Publication Number Publication Date
EP0405399A2 EP0405399A2 (de) 1991-01-02
EP0405399A3 EP0405399A3 (en) 1991-06-05
EP0405399B1 true EP0405399B1 (de) 1995-04-12

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EP19900112038 Expired - Lifetime EP0405399B1 (de) 1989-06-30 1990-06-25 Apparat zur Erzeugung von Röntgenstrahlen

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DE (1) DE69018525T2 (de)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4107199C2 (de) * 1991-03-06 1994-12-08 Siemens Ag Hochfrequenz-Röntgengenerator
GB9319867D0 (en) * 1993-09-27 1993-11-10 Eagle Lcs Limited X-ray sets
DE102006052285A1 (de) * 2006-11-03 2008-05-08 Dr. Simon Consulting Gmbh Hochspannungsnetzgerät
DE102013212099B4 (de) * 2013-06-25 2020-03-05 Trumpf Laser Gmbh Hochspannungsmodulation ohne Schleppfehler

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4338657A (en) * 1974-05-21 1982-07-06 Lisin Vladimir N High-voltage transformer-rectifier device
DE2814320C2 (de) * 1978-04-03 1984-02-16 Siemens AG, 1000 Berlin und 8000 München Röntgendiagnostikgenerator mit einer seinen Hochspannungstransformator aus einem Netzgleichrichter speisenden, zwei Wechselrichter aufweisenden Wechselrichterschaltung
DE2831093A1 (de) 1978-07-14 1980-01-24 Siemens Ag Roentgendiagnostikgenerator
FR2507842A1 (fr) * 1981-06-12 1982-12-17 Gen Equip Med Sa Regulateur de tension a semi-conducteur et generateur de radiologie comportant un tel regulateur
US4504895A (en) * 1982-11-03 1985-03-12 General Electric Company Regulated dc-dc converter using a resonating transformer
JPS62148651A (ja) * 1985-12-20 1987-07-02 横河メディカルシステム株式会社 Ｘ線断層撮影装置
US4823250A (en) * 1987-11-05 1989-04-18 Picker International, Inc. Electronic control for light weight, portable x-ray system

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DE69018525T2 (de) 1995-08-10
DE69018525D1 (de) 1995-05-18
EP0405399A3 (en) 1991-06-05
EP0405399A2 (de) 1991-01-02

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