Abstract: An infusion pump for the intravenous or intra-arterial infusion of liquid medicines has an electric drive and electronic control, with means so associated with the digital frequency control of the frequency generator (4) for operating the infusion pump motor that the delivered infusion dosage in changed step-by-step after an adjustable time delay by changing the frequency in dependence on physical parameters taken from the patient, and suddenly rising or falling changes in the physical parameters, which are outside a predetermined norm, cause the device to be switched off and generate an alarm.

Abstract: In interference current therapy, medium-frequency alternating currents are applied by means of electrodes to the body of a patient that is to be treated, the currents differing by a low-frequency difference frequency and interfering with each other in the area under treatment with development of a low frequency beat signal that can effect stimulation. Especially in the case of low frequencies, precise control of the frequency interference current is difficult, and at least one of the medium frequencies must be variable, for adjustment of the low frequency. According to the invention, a common oscillator is provided for both medium frequencies, the essentially higher frequency output of which is divided by a programmable divider into two or more frequencies that differ by the required amount, whereby at least one of the dividers is variable. Various schemes are described for execution of variable frequency division.

Abstract: In interference current therapy, medium-frequency alternating currents are applied by means of electrodes to the body of a patient that is to be treated, the currents differing by a low-frequency difference frequency and interfering with each other in the area under treatment with development of a low frequency beat signal that can effect stimulation. Especially in the case of low frequencies, precise control of the frequency interference current is difficult, and at least one of the medium frequencies must be variable, for adjustment of the low frequency. According to the invention, a common oscillator is provided for both medium frequencies, the essentially higher frequency output of which is divided by a programmable divider into two or more frequencies that differ by the required amount, whereby at least one of the dividers is variable. Various schemes are described for execution of variable frequency division.

Abstract: The primary field generated by a transmitting loop or coil energized with a AC current induces secondary currents within the body which in turn generate a secondary field. The secondary field is picked up by a pick-up loop or coil. A compensation coil is energized so that no voltage is induced in the pick-up coil when a reference body having the same resistivity is substituted for the body in which measurement are to be carried out. To compensate for body movements, the primary field can have a lower and a high freqency component. Since the high frequency components penetrate the body only to a predetermined depth (or not at all) the difference between the picked-up high or low frequencies signals is substantially independent of the distance between the object being measured and the measuring apparatus.

Abstract: Signals from a high frequency transmitter outside of the biological object are received in a resonant receiving circuit inside the object whose resonant frequency corresponds to the value of the parameter being measured. The signal from the resonant receiving circuit is applied to the input of a frequency multiplier whose output is connected to a second resonant circuit tuned to the multiplied frequency. The second resonant circuit transmits a return signal to a receiver outside of the biological object which is also tuned to the higher frequency. The signal at the receiver will have a maximum amplitude when the transmitter frequency is equal to the frequency of the first resonant circuit as tuned by the value of the parameter. The adjustment of the transmitter frequency required for receiving maximum energy at the receiver is a measure of the value of the parameter in a first embodiment.

Abstract: An apparatus for producing interference and beat-currents in a selectable point of the body, particularly for electrotherapy on the human body, which comprises at least two pairs of electrodes adapted to be applied to the human body. Each of the pairs of electrodes has associated therewith an output amplifier. The latter supplies independently selectively pulse and alternating current for each pair of the electrodes. A voltage proportional in amplitude to the current flowing through the patient is taken. The voltage relates mathematically each individual setting voltage with a common setting and is subtracted. The difference voltage is produced separately for each circuit and used for the amplification control on the corresponding of the amplifiers, and the voltage is so polarized that an increase in patient current resulting in a decrease of the amplification and an increase in the joint voltage resulting in an increase of the amplification.