Abstract: A pick-up and/or display device comprises a memory in which a video signal is written at a write frequency under the control of a clock and is read therefrom at a read frequency. Image expansion or image compression can thus be realized. The clock, a clock input of which is connected to a synchronizing pulse generator, comprises an oscillator having an adjustable frequency, an oscillator output constituting a clock output and being connected to a frequency divider whose output signal is applied to an integrating comparator circuit, an output signal variation of which is proportional to a difference between a mean input signal and a predetermined reference voltage, the comparator circuit being connected to a frequency set input of the oscillator, the oscillator comprising a trigger input which serves to switch the oscillator on and off and which constitutes the clock input.

Abstract: The invention relates to an X-ray imaging system, comprising an X-ray source for emitting an X-ray beam, a power supply unit which is connected to the X-ray source, an X-ray detector for converting the X-ray beam into an optical image, a television pick-up device for converting the optical image into a video signal, a detection device which is connected to the television pick-up device and which serves to form a control signal from the video signal, an output of the detection device being connected to the power supply unit for adjustment thereof, and a display unit which is connected to the output of the television pick-up device via an amplifier (18). When the reciprocal of the signal generated by the detection device is used as the gain factor for the amplifier, a stable brightness is obtained on the television monitor without giving rise to a light flash when the X-ray source is switched on.

Abstract: A television pick-up tube in an image pick-up system comprises an high-frequency magnetic deflection element which deflects the electron beam perpendicularly to the line direction in the television pick-up tube. As a result, residual charge remaining between the image lines on the target face of the television pick-up tube is neutralized. Inductive coupling of the high-frequency deflection element to the power supply increases the resonance frequency of the deflection element, so that the deflection element can operate at a frequency which exceeds the video signal frequency so that it does not interfere therewith.

Abstract: A device for forming an image of an object by means of ultrasound beams, comprising an array (1) of electroacoustic transducers, means for connecting a selected group of transducers to a delay unit (17) which is arranged to delay the electric signal generated by each transducer of the group by a predetermined period of time and to sum the delayed signals in order to form a resultant signal which is an electrical representation of the acoustic signals originating from a selected distance or from a selected direction. The delay unit (17) is formed by a tapped delay line (19), whose taps (21) serve as inputs for the signals originating from the various transducers and whose output (23) is connected to a signal processing device (25) for the further processing of the resultant signal. Signals are applied to the taps through current sources. The applied signals may be selectively attenuated to effect apodization of the ultrasound beam.