Abstract: In X-ray tubes comprising a metal grid, it may occur that the necessary emission current cannot be reached in unfavorable circumstances. This situation is improved by the invention in that the high voltage for the X-ray tube is derived from at least three series connected high voltage generators, the first and the second generator being connected to the anode and the cathode, respectively, of the X-ray tube while the third generator can be connected either to the anode side (in the case of high tube voltages) or to the cathode side (in the case of low tube voltage) by means of a switching device.

Abstract: An X-ray generator comprising two high voltage generators which supply a positive and a negative potential to the anode and cathode, respectively, of an X-ray tube. The high voltage generator connected to the cathode is connected in series with a grid-controlled electron tube. The X-ray tube has a grounded electrode between its anode and cathode. If the grid voltage of the electron tube is changed so that the anode potential decreases, then there is an increase in the X-ray tube voltage and an increase in the voltage between the anode and electrode of the X-ray tube, thus increasing the tube current. Tube current and voltage are thus varied in the same sense by modifying the grid voltage, thus producing a fast dose rate control.

Abstract: A circuit to avoid excess voltages when the high voltage transformer of an X-ray generator is switched on. The circuit includes a second thyristor connected in series with a damping resistor and coupled in parallel with the starting thyristor for the X-ray tube. Said second thyristor is turned on simultaneously with the high-voltage starting signal, while the first (starting) thyristor (without a series-connected resistor) is turned on with a certain delay. This delay increases as the tube current decreases. Thus, excessive voltages during switching on can be eliminated independently of the value of the tube current with the addition of only a single damping resistor and a thyristor.

Abstract: In an X-ray generator with dose rate control, useful for both tomographic exposures, i.e., exposures with a fixed, preset exposure time, and also for Bucky exposures when different limit times are preset for given organs; including a tube power control which prevents the tube limit power from being exceeded during dose rate control. During tube power control, the current and the voltage are changed in opposite directions with respect to each other, so that the dose rate can be changed while the tube power remains constant.

Abstract: In spite of optimum density on the film, tomography using automatic exposure control can produce exposures which have a less pronounced movement unsharpness than could be expected on the basis of the geometrical proportions. It was found that such effects always occur when the tube power resulting from the exposure control substantially deviates from the tube power initially adjusted. Therefore, means are provided which enable, in dependence of this difference, the exposure data to be changed for the next exposures of a series of tomographic exposures.

Abstract: A generator circuit for a rotary anode x-ray tube in which the anode (rotor) and the stator are maintained at the same D.C. level thereby permitting a smaller air gap between the rotor (anode) and stator, resulting in a faster run-up, and a quicker switch-over from fluoroscopic to exposure operation.

Abstract: The exposure time in X-ray generators comprising a high-voltage generator which is actuated on the primary side is shorter than the actuation time on the primary side. This is because the high-voltage on the secondary side can follow the voltage on the primary side only at a given delay due to the stray inductance of the transformer. The effective exposure time (i.e. the time during which the X-ray tube emits the desired radiation), consequently, is shorter than the exposure time which is adjusted on the control panel, the reduction also being dependent of the tube current. So as to achieve that the effective exposure time is equal to the exposure time adjusted on the control panel, means are provided which prolong the actuation time in dependence of the exposure current.

Abstract: In six-pulse and twelve-pulse X-ray generators, the objectionable ripple at double mains frequency caused by the low thermal inertia of the filament is here cancelled out by an opposing ripple deliberately introduced by unbalancing the three-phase system.

Abstract: In an X-ray generator, different starting powers may be selected and corresponding to each starting power a different reduction instant is measured at which time resistors are inserted into the high-voltage and the filament circuits to reduce power. Different starting powers may be associated with different organ exposures in which case the system has advantages similar to those where the load is reduced in several steps without the high cost.

Abstract: The invention relates to a time-measuring device for an X-ray generator comprising an automatic exposure device. The measurement of the actuation time which is controlled on the primary side by an automatic exposure device is inaccurate because the effect exposure time, which is the time during which the X-ray tube emits the desired radiation, is shorter than the actuation time in the primary circuit. This is due to the fact that, because of the always present stray inductances and cable capacitances etc., the high-voltage on the secondary side can follow the voltage on the primary side only with a given delay. For the accurate measurement of the effective exposure time, therefore, the actuation time is reduced by an amount which is dependent of the exposing tube current.