EP0035433A1 - Sicherheitsvorrichtung für Hochspannungsgenerator, insbesondere Röntgengerät - Google Patents

Sicherheitsvorrichtung für Hochspannungsgenerator, insbesondere Röntgengerät Download PDF

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Publication number
EP0035433A1
EP0035433A1 EP81400268A EP81400268A EP0035433A1 EP 0035433 A1 EP0035433 A1 EP 0035433A1 EP 81400268 A EP81400268 A EP 81400268A EP 81400268 A EP81400268 A EP 81400268A EP 0035433 A1 EP0035433 A1 EP 0035433A1
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Prior art keywords
voltage
transistor
resistor
whose
signal
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EP81400268A
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English (en)
French (fr)
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EP0035433B1 (de
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Raoul Setbon
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Thales SA
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Thomson CSF SA
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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
    • H05G1/26—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
    • H05G1/26—Measuring, controlling or protecting
    • H05G1/54—Protecting or lifetime prediction

Definitions

  • the present invention relates to a safety device for very-high-voltage, in particular radiological, generators of the type comprising at least one active, controllable element, such as a vacuum tube and control grids inserted between at least one of the electrodes. of the X-ray tube and at least that of the poles of the very-high-voltage source which is intended to polarize this electrode.
  • These grid tubes serve, on the one hand, as switches to energize the X-ray tube for the duration of exposure (exposure) when they are controlled to conduct by a positive rectangular signal applied to their grids. control during installation and, on the other hand, to apply between the electrodes of the X-ray tube a voltage determined by the amplitude of this signal which is obtained by means of a regulation loop which receives a preset preset voltage by the user.
  • Generators with regulation of the X-ray tube voltage using an electronic grid tube are well known, in particular from previous publications GB-A-689,798 and 689,799 (see preamble to claim 1) (US-A -2 659 016, or DE-B-974 342), or FR-A-1 395 015 (GB-A-1 077 742 or US-A-3 333 104), or DE-B-21 16 064.
  • the object of the safety device is to provide better protection for the patient, operators and electrical equipment according to the new international standards IEC 601-1, as well as radiological protection, that is to say against excessive doses of ionizing radiation applied to the patient, according to international standard IEC 407 and the American sanitary regulations (Regulations of the Bureau of Radiological Health - of the Food and Drug Administration -21 CFR Sub J 1020), ensuring, during a priming of the X-ray tube, in particular, a rapid cut-off of its THT supply to limit the residual energy passing through the tube to the few joules stored in the power cables, and, in order to avoid repeating the entire examination, a rapid automatic reset allowing the THT to be reapplied to the X-ray tube at short notice by the command grid tubes.
  • Known safety devices used with generators of the type described, are provided with relays which react, upon priming, with a relatively slow response time which can lead to the destruction of the X-ray tube and associated components and, they interrupt the current examination so that irradiation by the patient was unnecessary.
  • kenotrons have been inserted, that is to say high-voltage vacuum diodes, between the grid tubes and the X-ray tube to protect it by a current limitation, because their filaments are heated so as to limit the maximum intensity of the current consumed to a value close to that necessary for exposure, in the event of priming of the X-ray tube.
  • This requires two additional high-insulation heating transformers and elements for adjusting the heating current of the kenotrons coupled to that of the X-ray tube.
  • the safety device object of the present invention, makes it possible to avoid the drawbacks of the prior devices, on the one hand, by allowing, during primings, even repeated, of the X-ray tube, to continue the examination in progress thanks to the brief blocking of the application of very-high-voltage so as to defuse it quickly (discharge of energy in the cables) and rapid automatic reset (a few tens of microseconds after discharge) which can make this cut almost negligible and, on the other hand, to stop the examination in progress, when the tube has repeated priming at close intervals.
  • a safety device for an X-ray generator comprising, inserted between at least one of the terminals of a very-high-voltage DC source and at least one of the electrodes of an X-ray tube, at least an anode-cathode path of a vacuum tube and control grid supplied with the aid of a regulation circuit providing it with a rectangular signal whose duration determines that of the installation and whose amplitude, adjustable by variation a set voltage applied to the input of at least one comparator circuit, determines the voltage drop across this path and, therefore, the supply voltage of the X-ray tube, is mainly characterized by the fact that 'at least one current measurement resistor in the X-ray tube, inserted between at least the other source terminal and ground, supplies a first analog comparator, the output of which becomes saturated (closed), when the voltage drop caused by this current exceeds one predetermined threshold indicating the priming of the tube, so as to control the blocking of the transmission of the rectangular gate control signal, by means of an analog gate, in order to
  • the measurement resistor also supplies a first integrating circuit making it possible to integrate voltage drop pulses corresponding to overcurrents of the current due to strikes which, when they are repeated at short intervals, increase its integrated output voltage which is applied to a triggerable bistable rocker by exceeding a predetermined threshold voltage, the output of the bistable rocker then controlling the saturation of a switching transistor bringing back the setpoint input of the regulation to ground, so as to block this at least one grid tube, a signal, called a second time signal, applied by manual control allows the reset of the bistable rocker as well as the blocking of the switch transistor shorting the setpoint.
  • the reference 1 represents the X-ray tube supplied by two very-high-voltage (THT) power supply units 2 and 3 connected in series and each supplying substantially the same voltage.
  • the two blocks 2 and 3 can be consisting of two sets of three-phase secondary windings, each supplying a set of two-wave rectifiers, the output terminals of which are joined together by a series circuit consisting of a filtering capacitor and a resistor (see publication DE-B-1 029 429 and FR-A-1 395 015).
  • junction of the two blocks 2 and 3 that is to say that of the negative pole of the first 2 with the positive pole of the second 3, is joined to ground so that the voltage between the two output terminals (positive poles of the first 2 and negative of the second 3) is substantially twice their tension with respect to the mass.
  • the radiological generator further comprises, according to the teaching of previous publications GB-A-689,798 and 689,799 and FR-A-1,395,015, a first tetrode 4 whose anode is connected to the positive pole of the first block 2 and the cathode at the anode of the X-ray tube 1 and a second tetrode 5 whose anode is connected to the cathode of the tube 1 and its cathode at the negative pole of the second block 3.
  • These tetrodes 4, 5 are intended, for a on the one hand, to carry out the tensioning of the X-ray tube 1 as an electronic switch and, on the other hand, to constitute variable ballast resistances at the terminals of which the anodic current of the X-ray tube 1 which crosses them causes voltage drops , similar to those at the adjustable resistance terminals, which are subtracted from the very-high voltage supplied by the two blocks 2, 3 in series, so as to vary that between the anode and the cathode of the X-ray tube 1.
  • the negative terminals of the first block 2 and positive of the second block 3 are respectively joined here to ground by means of two current measurement resistors 6 and 7 of the same value, at the terminals of which the current of the X-ray tube 1 causes symmetrical voltage drops with respect to the mass at zero potential and proportional to it.
  • These measurement voltage drops are respectively applied to two inputs 11 and 12 of a safety device 10 according to the invention, which will be described later, by means of two conductors 8 and 9.
  • the actual value of the anode-cathode voltage of the X-ray tube 1 is measured using two resistive divider arrangements, the first of which, consisting of two resistors 81 and 82 in series, is connected between the anode and the ground and the second, also composed of two resistors 83 and 84 in series, is connected between the cathode and the ground.
  • the midpoint of the first divider 81-82 is connected to a first input 31 of a comparator and modulator circuit 30, a second input 32 of which is connected to the midpoint of the second divider 83-84.
  • This first input 31 is connected to one of the inputs of a first differential amplifier 300, the other input of which receives a third input 33 connected to.
  • the first output 21 of a setpoint generator circuit 20 the positive rectangular setpoint signal whose adjustable duration determines the exposure (exposure time) to and whose adjustable amplitude determines the anode-cathode voltage of the X-ray tube 1.
  • the second input 32 of the circuit 30 is connected to one of the inputs of a second differential amplifier 301, identical to the first 300, the other input of which is supplied by an analog inverter stage 302 (of polarity) providing a signal of the same value that, to that applied to its input but of opposite polarity.
  • This input of the inverter stage 302 is connected to the third input 33 which supplies it with the above-mentioned reference signal.
  • the amplifiers 300, 301 can be produced using conventional differential amplifiers of the symmetrical type, equipped with vacuum tubes (triodes) or transistors, or even using linear integrated circuits (operational amplifiers ).
  • the output of the first amplifier 300 is connected, via a first choke 303, to the control grid of a first high-frequency penthode 305 with variable slope in function of its grid-cathode polarization equipping a first amplitude modulator.
  • the output of the second amplifier 301 is connected, by means of a second shock inductor 304, to the control grid of a second pentode 306 equipping a second amplitude modulator.
  • the control gates of pentodes 305 and 306 are respectively coupled to two outputs of a high-frequency oscillator 307 (2.2 MHz) via two coupling capacitors 308 and 309.
  • the cathodes of pentodes 305 and 306, connected to their suppressor grids, are brought to a positive potential with respect to ground using a first DC voltage source 310 which also supplies the positive power inputs of the amplifiers 300 , 301, the negative power inputs of which are supplied by a second source 311 which is symmetrical with respect to ground.
  • a first DC voltage source 310 which also supplies the positive power inputs of the amplifiers 300 , 301, the negative power inputs of which are supplied by a second source 311 which is symmetrical with respect to ground.
  • the gate potential approaches that of the cathode, while when it is positive, the grid potential tends towards the cut-off voltage where the slope and, consequently, the gain of the modulator stage decreases to stabilize during installation, to a corresponding value to the amplitude of the setpoint signal.
  • the anodes of pentodes 305, 306 are respectively connected to primary windings tuned by two high-frequency transformers 61, 71 forming respectively part of the amplitude detector circuits 60 and 70.
  • the windings transformers 61, 71 which must be highly isolated from the primaries, each supply a peak detector assembly 62 composed of a diode 63 in series with mounting of a secondary capacitor 64 in parallel with a resistor 65 through which the gate of another amplifier pentode 41 is negatively biased, the anode of which is connected to the cathode of tetrode 4.
  • This biasing of the control gate is obtained by means of a third variable DC voltage source 66 whose positive pole is connected to the cathode of the other pentode 41 and whose negative pole is connected to one of the terminals of the resistor 65 whose other terminal is connected to the grid of it.
  • the other pentode 41 is supplied with DC voltage using two other DC voltage sources 42, 43 in series, one of which 42 is connected by its negative pole to the cathode of the other pentode. 41 and by its positive pole to the negative pole of the other 43, which is also joined to the control grid of the tetrode 4 by means of a resistor 44 to polarize it negatively.
  • the positive pole of the other source 43 is joined by a load resistor 45 at the junction of the anode of the other pentode 41 with the cathode of the tetrode 4.
  • the current passing through the other pentode 41 causes at the terminals of the resistor 45 a voltage drop of opposite polarity to that of the voltage supplied by the other source 43.
  • the polarization of the other pentode 41 is initially adjusted so that it is polarized at the limit of the cut in the absence of a signal detected at the terminals of parallel mounting 64-65.
  • a detected high-frequency wave train provides a substantially rectangular positive signal to the gate of pentode 41 which then begins to conduct an anode current which is a function of the amplitude of this wave.
  • This anode current causes a voltage drop across the resistor 45 which is subtracted (subtracted) from the negative bias voltage supplied by the other source 43 which keeps the tetrode 4 blocked.
  • the tetrode 4 begins to conduct in response to the increase in its grid-cathode voltage (decrease in its negative polarization) a current which passes through the X-ray tube 1 and its internal resistance, that is to say the difference of its anode-cathode potential is a function of the amplitude of the setpoint signal throughout its duration.
  • each tetrode 4, 5 is controlled by a regulation loop specific to it as a function of the amplitude of the reference signal so that the cathode potentials of the first 4 and anode of the second 5 are symmetrical with respect to the ground.
  • the safety circuit 10 intervenes in these two regulation loops at two distinct levels, during the priming of the X-ray tube 1.
  • the interval between two or several successive primings is greater than a predetermined interval using an integrating circuit (time constant)
  • it acts only on the control grids of the pentodes 305, 306 of the modulators, by applying to them for a brief instant, negative voltages beyond the cut through its outputs 15 and 16 respectively connected by the fourth 34 and fifth 35 inputs of the circuit 30 to the outputs of the amplifiers 300 and 301.
  • a threshold bistable rocker controls the grounding of its fourth input / output 14 by an electronic switch preventing transmission of the setpoint signal towards the third input 33 of the comparator and modulator circuit 33, since the first output 21 of the setpoint generator 20 is connected to the fourth input / output 14 via a resistor 23.
  • FIG. 2 there is shown schematically one of the preferred embodiments of the safety circuit 10 of Figure 1, according to the invention, with its first two signal inputs 11 and 12 connected to the respective terminals of the measurement resistors of the current 6, 7 (about ten ohms) of the radiological generator circuit, with its third input 13 connected to the second output 22 of the reference generator 20 (of FIG. 1) which provides positive rectangular control signals, of amplitude constant (+ 6V) whose duration is that of the installation, with its fourth input / output 14 connected in parallel with the third input 33 of the comparator and modulator circuit 30 and, through a resisatnce 23, to the first output, called the setpoint, 21 of the generator 20 and with its two outputs 15 and 16 respectively connected to the inputs 34 and 35 of circuit 30.
  • the safety circuit 10 further comprises two power inputs 17, 18 of which the first 17 is connected to the positive pole of a continuous low-voltage source (+ 24 V) and the second of which 18, connected to the chassis mass, is connected to the negative pole thereof.
  • the positive supply input 17 is, for example, connected via a first diode 101 and a resistor 102 for limiting the current (of a few tens of ohms) to the positive armature of a capacitor.
  • electrochemical filtering 103 (of a few hundred microfarads) whose negative armature is connected to the negative supply input 18 (ground) so that its positive terminal 104 supplies the supply voltage of one of the elements (rocker at threshold) of circuit 10.
  • the first two inputs 11 and 12 are combined here together using a resistive voltage divider comprising two resistors 105 and 106 in series (of the same value, for example, a few tens of ohms) whose midpoint 107 feeds, via another resistor 108 (of the order of kilohm) and a parallel circuit composed of a resistor 109 (of a few tens of kiloohms) and a coupling capacitor 110 (of the 'order of the microfarad), the base of a junction transistor of the NPN 111 type (switching) whose emitter is connected to the second input 12.
  • a resistive voltage divider comprising two resistors 105 and 106 in series (of the same value, for example, a few tens of ohms) whose midpoint 107 feeds, via another resistor 108 (of the order of kilohm) and a parallel circuit composed of a resistor 109 (of a few ten
  • transient suppressor devices are generally Zener or avalanche type diodes, having a voltage for which they remain blocked ("stand-off voltage”), a starting voltage for which they start to conduct and a setting voltage ( “clamping voltage”), function of the current which flows through them and which appears at its terminals during a voltage transient, and a maximum current specified, such as, for example, those of type UZS 306 to 327 from the American company "UNITRODE CORPORATION ".
  • the other respective terminals of the resistor 115 and (the cathode) of the transient suppressor 116 are connected to ground (terminal 18) and the anodes of the diodes 113 and 114 are respectively joined by two resistors 117 and 118 at the outputs 15 and 16 of the circuit 10.
  • the X-ray tube 1 When the X-ray tube 1 is primed following a degassing (thermal, for example) the current flowing through it suddenly increases and causes rapid increases in voltage drops across the measurement resistors 6 and 7 which are applied respectively with positive polarities at input 11 and negative at input 12 of the safety circuit 10.
  • the predetermined fraction of the sum of these voltage drops, supplied by the midpoint 107 of the divider 105-106 is applied through the resistor 108 and the parallel mounting 109-110 at the base of the first transistor 111 which starts to conduct when this fraction exceeds a threshold of about 0.7 volts which corresponds to an anode current of the tube 1 which exceeds its nominal current by a percentage previously selected .
  • the steep edge of the voltage drop between the input terminals 11 and 12 of the circuit crosses the capacitor 110 so as to quickly control the saturation of the transistor 111.
  • the capacitor 110 then charges at a voltage proportional to the peak value of the current ignition, through the resistor 108 and the base-emitter junction of the transistor 111. From that the starting current has stopped growing, the capacitor 111 no longer charges and the base current of transistor 111 also ceases. The charge accumulated across the capacitor 110 therefore negatively polarizes the base of the transistor 111, while discharging slowly through the resistor 109.
  • the duration of the temporary disjunction is a function, in particular, of the maximum intensity of the discharge current and of the voltage applied to the tube 1. Its limitation is due in particular to the rapid cutting of the tetrodes 4, 5 which isolate the tube from the blocks 2 and 3 including the THT filtering capacitors where a significant amount of energy (Z Cy2, where V is about 80 kV) is stored.
  • the high-voltage switching transistor 111 controlling the brief tripping can be replaced by a switching threshold comparator, obtained by means of linear integrated circuits (operational feedback amplifier) or high gain differential amplifier for which a threshold voltage is chosen so that it corresponds to a voltage drop across resistors 6 and 7, caused by a slight overshoot of the nominal current, in the X-ray tube 1 (from 20 to 50 percent, for example).
  • a switching threshold comparator obtained by means of linear integrated circuits (operational feedback amplifier) or high gain differential amplifier for which a threshold voltage is chosen so that it corresponds to a voltage drop across resistors 6 and 7, caused by a slight overshoot of the nominal current, in the X-ray tube 1 (from 20 to 50 percent, for example).
  • the voltage drop at the opposite terminals of the two resistors 6 and 7 in series, caused by the current in the X-ray tube 1 is also applied to an integrator circuit 120 composed of a resistor 121 and a capacitor 122 connected in series between the first 11 and second 12 input terminals of circuit 10, the time constant of which has been chosen so as to trigger the switching from the blocked state to the saturated state of a bistable rocker 130 whose input 131 is supplied by the output 123 of the integrator circuit 120, for two or more successive starts and close to the tube 1, that is to say within a time interval determined by the time constant (for example less than several milliseconds), which indicate a defect in the X-ray tube 1.
  • the time constant for example less than several milliseconds
  • the bistable rocker 130 used here is of the type with two complementary transistors 132, 133 (see, for example, publication GB-A-1,303,410) which are simultaneously blocked or saturated because the collector current of one attacks the base of the other and vice versa.
  • the first NPN 132 transistor of the rocker 130 is connected by its base to the trigger input 131 which is supplied by the output 123 of the integrator circuit 120.
  • the collector of the first transistor 132 is connected to one of the terminals of a first resistor 133 (of about ten kiloohms), the other terminal of which is connected to the base of the second PNP type transistor 134 and to one of the terminals of a parallel circuit, composed of a second resistor 135 ( of the order of a kiloohm) and of a capacitor 136 of low capacity (of the order of nanofarad), the other terminal of which is connected to the emitter of the second transistor 134.
  • the emitter of the second transistor 134 is also connected to the positive armature 104 of the filtering capacitor 103, which supplies the rocker 130.
  • the collector of the second transistor 134 is joined, on the one hand, via a third diode 137 and a third resistor 138 at the base of the first 132 so as to provide it with a holding current in its state its grounded and, on the other hand, via a fourth resistor 149 and a second light-emitting diode 140 for signaling, to ground (18).
  • bistable rockers can also be used for this purpose, such as that called the SCHMITT type (with threshold) or even bistable locking rockers ("latch").
  • the blocking of the second transistor 134 is controlled here by a third transistor 141 of PNP type, serving as reset switch, whose collector-emitter path joins together the base and the emitter of the second 134 and which is normally blocked and controlled on its base using a fourth NPN transistor 142, mounted as a common emitter. This receives on its base positive rectangular signals of constant amplitude (+ 6 V) and of duration corresponding to the exposure time, provided by the second output 22 of the setpoint generator 20 (FIG.
  • a differentiating coupling circuit comprising a coupling capacitor 146 in series with another resistive voltage divider composed of two resistors 147 and 148 in series, is connected between the collector of the fourth transistor 142 and the emitter of the third 141 connected to terminal 104 (+ V DC ), the junction of resistors 147 and 148 being connected to the base of the third transistore 141 so that it receives negative pulses with respect to its transmitter, the front edge of which coincides with that rectangular signals supplied by the output 22 so as to temporarily saturate the third transistor 141 for a short period of time in order to cause the reset of the bistable rocker 130 at the start of each exposure.
  • These rectangular signals are generally triggered by the operator and its called “second time” signals, indicating the start of a new radiological examination (or a new series of these examinations), whether there has been a disjunction caused by the rocker 130 or not during the previous installation, to allow reapply the setpoint signal at the input 33 of the circuit 30 ( Figure 1).
  • the output 139 of the rocker 130 that is to say the collector of its second transistor 134, is connected through a fourth diode 150, a resistor 151 and a fifth diode 152 in series, at the base of a fifth transistor 153, the collector of which is connected via the input / output 14 to the reference input 33 of the comparator and modulator circuit 30 (FIG. 1) and, via a resistor 23, at the first output 21 of the setpoint generator 20 (FIG. 1) supplying the setpoint signal which controls the energization of the X-ray tube 1 (figure 1).
  • the emitter of the fifth transistor 153 is connected to ground, in particular by the sheath (shielding) of the coaxial cable used to transmit the setpoint signal, to the anode of a sixth diode 154 (of "clamping") and to the one of the terminals of another resistor 155, the other terminal of which is connected to the junction of the resistor 151, of the anode of the fifth 152 and of the cathode of the sixth diode 154.
  • the resistors 151 and 155 form for the output signal of the switch (varying between 0 and + 23 V, approximately) a voltage divider.
  • comparators 300, 301 each receiving at one of their inputs setpoint voltages of substantially zero value, therefore very different from the actual values, their outputs then rapidly supply voltages close to their negative supply voltage, which causes the blocking of the modulators which are polarized, in the absence of a setpoint, at the cut-off and, consequently, the cut-off of the tetrodes 4, 5.
  • This general lock-up remains until a reset carried out by the operator or (the program d 'an external computer) in the form of the aforementioned second time signal which controls the reset (blocked state) of the rocker 130 and, consequently, the blocking of the transistor-switch 153 allows both the reapplication of the setpoint at input 33 ( Figure 1).
  • the junction of the input / output 14 with the collector of the fifth transistor 153 is combined at the junction of the resistors 151, 155 with the anode of the fifth 152 and the cathode of the sixth diode 154, by a capacitor 158 of capacity chosen as a function of the desired modification of the rise time of the reference signal.
  • This capacitor 158 in conjunction with the transistor 153, has the effect of transforming the front into a linearly increasing ramp, of rise of the rectangular setpoint signal, that is to say of significantly reducing the slope of its rising edge, so that the application of very-high voltage to the X-ray tube 1 is carried out more gradually.
  • the capacitor 158 is charged across the resistor 155 by a gradually decreasing current which causes a similar voltage drop across its terminals. This drop in voltage has the effect of making the fifth transistor 153 conductive, which will then constitute an initially low but gradually increasing internal resistance as a function of the charge current of the capacitor 158 and in parallel with its charge circuit.
  • the charge of the capacitor 158 by a linearly decreasing current and the linearly increasing resistance of the collector-emitter path of the fifth transistor 153 which forms with the resistor 23 a variable voltage divider, has the effect that the reference signal applied to the input 33 of the comparator circuit 30 (FIG. 1) will have a gradual, substantially linear rise (limiting the dv / dt that the components of the generator must withstand and, therefore, the overvoltages which may appear at various points thereof).
  • the fourth transistor 142 which receives on its base a positive rectangular signal during the whole installation, is, moreover, joined by its collector at the base of the fifth transistor 153 by means of a seventh diode 156 and a resistor 157 serial.
  • the signal controlling the base of the fourth transistor 142 becomes null and this one blocks.
  • the collector voltage rises to the supply voltage (+ V DC ) which causes a current flowing from terminal 104, through collector resistor 145, the seventh 156, the base resistor 157 and the base-emitter junction of the fifth transistor. 153, to the mass by saturating the latter. This then makes it possible to discharge the capacitor 158 through the resistor 155 and its collector-emitter path.
  • the seventh diode 156 makes it possible to isolate the collector of the fourth transistor 142 from the base of the fifth 153, when the rectangular signal at constant amplitude coincides with the reference signal and saturates the fourth transistor 142.
  • the circuit comprising the fifth transistor 153 and the capacitor 158 in series with the resistor 155 exerts two distinct functions, the first of which is to function as a switch short-circuiting the arrival of the voltage setpoint to the comparator and modulator circuit 30 (FIG. 1), during repeated and close priming of the X-ray tube 1 detected using an integrator (120) and the tilt threshold of a bistable locking rocker (130 ).
  • the second function of this circuit is to modify the rise time of the rectangular setpoint signal, thanks to the capacitive coupling between the collector and the base of this transistor 153 which, in conjunction with the circuit which surrounds it: it then plays the role of a well-known "MILLER" integrator, to which it is analogous.
  • circuit of transistor 153 fulfilling two functions by two distinct circuits, one of which would be an electronic switch controlled by the rocker 130 and the other of which would be an integrator of known type, equipped with transistors or of integrated circuits, at the cost of an increase in circuit 10.

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  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • X-Ray Techniques (AREA)
EP81400268A 1980-02-29 1981-02-20 Sicherheitsvorrichtung für Hochspannungsgenerator, insbesondere Röntgengerät Expired EP0035433B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8004603 1980-02-29
FR8004603A FR2477331A1 (fr) 1980-02-29 1980-02-29 Dispositif de securite pour generateur de tres haute tension, notamment radiologique

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Publication Number Publication Date
EP0035433A1 true EP0035433A1 (de) 1981-09-09
EP0035433B1 EP0035433B1 (de) 1984-02-08

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EP81400268A Expired EP0035433B1 (de) 1980-02-29 1981-02-20 Sicherheitsvorrichtung für Hochspannungsgenerator, insbesondere Röntgengerät

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US (1) US4402086A (de)
EP (1) EP0035433B1 (de)
JP (1) JPS56136499A (de)
DE (1) DE3162141D1 (de)
FR (1) FR2477331A1 (de)

Cited By (1)

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EP0080691A2 (de) * 1981-11-30 1983-06-08 Kabushiki Kaisha Toshiba Detektionsschaltung bei Betriebsstörung für eine Röntgenröhre

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CA1120600A (en) * 1977-09-23 1982-03-23 Heikki K.J. Kanerva Procedure for regulating and stabilizing the intensity level of the radiation of an x-ray source and an x-ray source where this procedure is used
US4734924A (en) * 1985-10-15 1988-03-29 Kabushiki Kaisha Toshiba X-ray generator using tetrode tubes as switching elements
US7340035B2 (en) * 2004-10-13 2008-03-04 General Electric Company X-ray tube cathode overvoltage transient supression apparatus
PL1855261T5 (pl) * 2006-05-11 2014-11-28 Siemens Schweiz Ag Sposób i urządzenie do monitorowania linii sygnalizacyjnej instalacji sygnalizatorów pożarowych pod kątem zakłóceń
JP6257948B2 (ja) * 2012-08-07 2018-01-10 東芝メディカルシステムズ株式会社 Ｘ線撮影システム
US10262829B2 (en) * 2015-12-14 2019-04-16 General Electric Company Protection circuit assembly and method for high voltage systems
CN110547819A (zh) * 2019-09-11 2019-12-10 山东新华医疗器械股份有限公司 一种ct的智能控制装置和方法
CN112688535B (zh) * 2020-12-30 2022-07-05 上海联影医疗科技股份有限公司 上电控制系统

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DE2116064C3 (de) * 1971-04-02 1975-11-13 Siemens Ag, 1000 Berlin Und 8000 Muenchen Röntgenapparat mit einem Hochspannungsregelkreis, der ein in Serie zu einer Röntgenröhre liegendes, von einem Regelverstärker gesteuertes Regelventil aufweist

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Elektrotechnische Zetischrift (ETZ) B, Vol. 10, No. 7, 1958, Berlin, DE K. BISCHOFF: "Die Entwicklung der Medizinischen Rontgentechnik in den Letzten 12 Jahren", pages 267-275 * figure 2 * *

Cited By (3)

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Publication number Priority date Publication date Assignee Title
EP0080691A2 (de) * 1981-11-30 1983-06-08 Kabushiki Kaisha Toshiba Detektionsschaltung bei Betriebsstörung für eine Röntgenröhre
US4520495A (en) * 1981-11-30 1985-05-28 Tokyo Shibaura Denki Kabushiki Kaisha Failure detection circuit for an X-ray tube
EP0080691B1 (de) * 1981-11-30 1986-05-07 Kabushiki Kaisha Toshiba Detektionsschaltung bei Betriebsstörung für eine Röntgenröhre

Also Published As

Publication number Publication date
EP0035433B1 (de) 1984-02-08
FR2477331A1 (fr) 1981-09-04
FR2477331B1 (de) 1984-02-17
DE3162141D1 (en) 1984-03-15
JPS56136499A (en) 1981-10-24
US4402086A (en) 1983-08-30

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