Siemens Aktiengesellschaft

Siemens Aktiengesell Schaft

Hans Ebersberger

Heribert Amtmann

Hans-Joachim Greiner

Horst Aichinger

Rudolf Friedel

Guenther Eckardt

Guenter Eckardt

An x-ray tube has an evacuated housing with a cathode and a rotating anode therein, the rotating anode including a drive shaft normally supported during operation by a magnetic bearing arrangement, but having mechanical bearings attached to the housing by which the shaft is supported if the anode 'drops' during operation. A disengageable contact is provided which, when closed, completes a circuit for supplying high voltage to the anode. A displaceable actuator extends into the evacuated housing for making and breaking the contact, the actuator being sealed air-tight within the housing by a spring bellows. The actuator has a guide element disposed outside of the evacuated housing, which permits the guide element to be lubricated as needed. A locking element is provided which is engageable with the guide element to hold the anode shaft, and thus the anode, in place against the mechanical bearings during transport of the x-ray tube.

Rotating anode x-ray tube

An x-ray tube has a rotary anode which is seated in a magnetic bearing unit which includes catcher bearings for supporting the anode system if the magnetic bearing is turned off or malfunctions. For this purpose the drive shaft of the rotary anode has a substantially conical surface carried thereon which is symmetrical with respect to the rotational axis of the shaft. The conical surface receives the catcher bearings therein with a gap existing between the bearings and the surface during normal operation, and in the event of failure of the magnetic bearing system, functions as a contact surface to limit movement of the shaft and hence of the anode. The conical surface may be formed by two inwardly chamferred rings carried on the shaft with the catcher bearing disposed between the facing chamferred edges. The catcher bearing may be chamferred in a complementary manner and may have a ball bearing assembly therein.

X-ray tube with a magnetically seated rotary anode

In the case of tubes with magnetically mounted anodes, it is difficult to obtain an adequately stable mounting of the anode shaft for all stresses to be expected, in particular, in the case of tilting and pivoting. To this end, the disclosure provides that magnetically conductive pole pieces are inserted in the wall of the tube envelope at the locations at which magnets are exteriorly disposed which pole pieces are in magnetic coupling relation with the anode arrangement. The distances between the parts to be magnetically coupled can thereby be substantially reduced, so that there results--in relation to known magnetic bearings--a substantially more stable support-mounting of the rotary anode in the high vacuum envelope. The disclosure is, in particular, applicable in the case of X-ray tubes for utilization in medical X-ray technology.

Rotary anode X-ray tubes

In an exemplary embodiment, the control circuit for controlling filament current to maintain x-ray tube voltage at a set point value is disabled near the beginning of an x-ray exposure by the cut-off of filament current to provide a falling load characteristic as a function of time. During the cooling of the x-ray tube filament, the x-ray tube voltage is maintained near its set point value by the timed switching of taps of a variable-ratio transformer to change the input voltage to the x-ray tube high voltage transformer, and by the coordinated changing of the loading of the primary circuit of such high voltage transformer, the control circuit for maintaining x-ray tube voltage at the set point value thereafter being placed in control of the filament current for the remainder of the x-ray exposure.

X-ray diagnostic generator in which the x-ray tube voltage is regulated

In an exemplary embodiment, in order to operate the X-ray diagnostic generator with a decreasing (or 'falling') load during an X-ray exposure, there is disposed in the primary circuit of the high voltage transformer a bridge rectifier in whose D.C. current branch there is disposed a series of networks each consisting of at least one resistance and one capacitor in parallel, and a switch for the purpose of switching the network into and out of the circuit. A timing control initially short circuits the resistance-capacitance networks to provide for maximum primary current at the start of an exposure, the shunt capacitor absorbing such primary current when each resistance-capacitance network is first switched into the circuit to initiate a relatively smoothly decreasing primary current as a function of time. As secondary voltage tends to decrease, the X-ray tube current is progressively reduced to maintain the selected X-ray tube voltage, the result being the desired smoothly decreasing load characteristic.

X-ray diagnostic generator in which the X-ray tube voltage is regulated

In an illustrated embodiment a radiation detector is to be arranged in front of a xeroradiographic cassette and yet to avoid adverse effects on the xerographic image. To achieve this the shielding layer for the cassette is a graphite layer and the electrode layer consists of a vacuum-deposited electrically conductive material having a low atomic number. Desirably the electrode layer has marginal zones which continuously decrease in thickness so that no sharp absorption contours are present which would be over-accentuated in xerographic image production. Because of the utilization of a graphite layer as a protective shield, the absorption of the radiation detector can be kept very small. Electrical contact with the vacuum deposited electrode layer may be by means of a graphite layer which is in electrical contact with the electrode layer.

Radiation detector for an automatic X-ray exposure timer

A soldering connection between metal and ceramics, wherein the parts consisting of metal and ceramics engage each other as a plug and a socket. The invention is particularly characterized in that only parts of metallic and ceramic surfaces which are next to each other are soldered to each other.

Growing community of inventors

Kotzenaurach, Germany

Hans Ebersberger