Transformer-isolated alternating current power supply
First Claim
1. An alternating current source for generating an alternating current (I) across the body of a patient (ZX), comprising A first transformer, which defines a patient side and a device side which is insulated from the patient side, and whose coil at the patient side leads to terminals, which can be connected to the patient, and A generator on the device side, which generates an alternating voltage or an alternating current, and which excites a coil at the device side in such a way that an alternating current is generated at the patient side upon connecting the terminals via the patient as the load (ZX), Means for converting the alternating current at the patient side into a control signal, which is accessible at the device side and isolated from the patient side, and which controls the signal generated by the generator.
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Accused Products
Abstract
Medical safety requires for measurement of electrical bioimpedance, wherein an alternating current is applied to the human body, an insulation barrier between the energy source, which provides the energy for the current, and the human being. This insulation barrier can be accomplished by utilizing a transformer. According to the invention, a signal representing the voltage at the output of the current source is used for a positive feedback to ensure that the current provided by the alternating current source is constant over a wide range of loads ZX and a wide range of frequencies. For instance, the alternating current applied to the human body by a transformer is measured with the help of a current measuring transformer and the measured signal utilized for controlling in a closed loop the alternating voltage at the input of the current source, which drives the transformer for the purpose of generating the alternating current.
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Citations
22 Claims
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1. An alternating current source for generating an alternating current (I) across the body of a patient (ZX), comprising
A first transformer, which defines a patient side and a device side which is insulated from the patient side, and whose coil at the patient side leads to terminals, which can be connected to the patient, and A generator on the device side, which generates an alternating voltage or an alternating current, and which excites a coil at the device side in such a way that an alternating current is generated at the patient side upon connecting the terminals via the patient as the load (ZX), Means for converting the alternating current at the patient side into a control signal, which is accessible at the device side and isolated from the patient side, and which controls the signal generated by the generator.
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18. An alternating current source for generating an alternating current (I) across the body of a patient (ZX), comprising
A first transformer (T), which defines a patient side and a device side which is insulated from the patient side, and whose coil at the patient side provides a first and a second terminal, which can be connected to the patient, and A generator on the device side, which generates an alternating voltage signal for controlling an alternating current source, wherein the alternating current source excites a coil at the device side upon connecting the first terminal and the second terminal via the patient as the load (ZX), wherein a voltage, which is measured across the coil at the device side of the transformer (T), is utilized for a positive feedback.
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22. Method for generating an alternating current incorporating the following steps:
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connection of a load (ZX) to a coil at the patient side of a transformer (T1), Generating an alternating voltage, Converting of the alternating voltage into an alternating current, Excitement of a coil at the device side of the transformer (T1) with the consequence of induction of an alternating current (I) in the coil at the patient side of the transformer (T1), Generating of a control signal, which is representative of the alternating current (I) at the patient side, Providing said control signal to a control, which controls the alternating voltage or the alternating current.
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Specification