Body composition analyzer
First Claim
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1. A body composition analyzer comprising:
- four electrodes for connection to a patient;
a constant current source circuit connected to one of the electrodes, the constant current source circuit comprising;
an oscillator providing an output to the one of the electrodes;
an instrumentation amplifier connected to the object of the oscillator; and
a full wave rectifier connected to the output of the instrumentation amplifier and supplying an error signal to the oscillator;
a magnitude detection circuit connected to two of the electrodes for measuring the current from the electrodes;
a phase detection circuit connected to receive two signals, one signal from the constant current source circuit and the other signal from the magnitude detection circuit, the phase detection circuit measuring the phase shift between the two signals; and
microcomputer means connected to the phase detection circuit and the magnitude detection circuit for measuring resistance and reactance of the patient and converting measurements to an indication of the amount of body fat.
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Abstract
An analyzer determines the amount of body fat on a patient by using a measurement of body impedence is based upon the nature of the conduction of an applied electrical current in the human body. The analyzer has a constant current source circuit for inducing a high frequency low-voltage signal in the body, and magnitude and phase detection circuits for measuring the magnitude and phase shift of the induced signal.
85 Citations
7 Claims
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1. A body composition analyzer comprising:
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four electrodes for connection to a patient; a constant current source circuit connected to one of the electrodes, the constant current source circuit comprising; an oscillator providing an output to the one of the electrodes; an instrumentation amplifier connected to the object of the oscillator; and a full wave rectifier connected to the output of the instrumentation amplifier and supplying an error signal to the oscillator; a magnitude detection circuit connected to two of the electrodes for measuring the current from the electrodes; a phase detection circuit connected to receive two signals, one signal from the constant current source circuit and the other signal from the magnitude detection circuit, the phase detection circuit measuring the phase shift between the two signals; and microcomputer means connected to the phase detection circuit and the magnitude detection circuit for measuring resistance and reactance of the patient and converting measurements to an indication of the amount of body fat. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification