Abstract: An apparatus for medical diagnosis and/or therapy includes an electromagnetic obstacle sensor in order to prevent collisions with, for example a patient to be examined. The sensor is constructed so as to include a radiation transmitter and a radiation receiver in the form of capacitive electrodes 16 and 18, respectively, whereto electronic circuits 26 and 28 for signal processing are connected. In order to enable the electrodes 16 and 18 and the electronic circuits 26 and 28 to be checked for correct operation, a test electrode 14 is connected between the transmitter electrode 16 and the detection electrode 18, which test electrode can be connected, if desired, to a point 32 of fixed voltage via a controllable switch 34. The presence of an obstacle is thus simulated. The output signal of the electronic circuits 26 and 28 can be checked to determine whether this output signal corresponds to the situation in which an obstacle is present.

Abstract: An apparatus for medical diagnosis and/or therapy which includes an electromagnetic proximity sensor (20-1, 20-2, 20-3, 20-4) which detects the presence of an object (for example, 28) directly in front of the sensor. By coupling the main drive directions 34-1, 34-2, 34-3 and 34-4 to the proximity sensors in such a manner that each main drive direction (for example, 34-4) substantially halves the exterior angle (.alpha..sub.4) between the two neighbouring proximity sensors (20-1, 20-4) and by inhibiting the displacement in the associated main drive direction (34-4) by these two neighbouring proximity sensors, it is achieved that all clearing movements remain possible and all movements leading to collisions are inhibited.

Abstract: An apparatus for medical diagnosis and/or therapy, includes an electromagnetic obstacle sensor. Due to variations of the ambient temperature and humidity and/or due to the hanging of, for example a cloth around the sensors (16,18), drift of the zero point of the control may occur, so that the approaching of an obstacle by a movable part (6) of the apparatus could be incorrectly interpreted by the apparatus. In order to compensate for such drift there is provided a control unit (25) for automatically controlling the output signal V.sub.o of the receiver (27) back to the zero value in the absence of an object in the vicinity of the movable part (6). This control preferably takes place at a comparatively high speed when a cloth or moisture is moved into the vicinity of the sensors, and at a comparatively low speed upon removal of the cloth or the moisture.

Abstract: An arrangement for collision prevention is provided for an apparatus, in particular an x-ray examination apparatus, having components that can be moved by drive means. A collision is detected by way of detecting the speed of a relevant moving part and detecting the current and/or power supply to the drive means. Reference values for current and/or power supply at normal operation in dependence of the speed acquired by moving components are provided from a memory means and actually required current and/or power supplies are compared to said reference values. In addition, actual positions of components are detected and compared to computed expected positions of said components. A collision is detected when the required current and/or power supply exceeds a relevant reference value and the detected actual position deviates from the corresponding calculated expected position.

Abstract: In an x-ray examination apparatus, a film holder is mounted on a frame, which itself is connected to the carrier, notably a C-arm, for the x-ray source and the image intensifier. When not in use, the film holder can be placed in a park position against the inner circumference of the C-arm, such that the film holder neither obscures, nor impedes access to the patient (region). The frame with the film holder can be rotated to a standby position next to the image intensifier, such that the film holder can be conveniently reached for preparation for exposure. Finally, the film holder can be rotated with respect to the frame into an exposure position in front of the image intensifier. The C-arm remains balanced for all three positions of the film holder; this is achieved by two counterweights that move along the outer circumference of the C-arm, just under its outer enclosure. Consequently, the C-arm can be moved manually without considerable effort.