Matsushita Electric Industrial Co., Ltd.

Yushi Nishimura

Hisashi Hagiwara

Kinya Hasegawa

Hiroshi Fukukita

One of pairs of an exciter and a sensor is selected in accordance with the detection signal which is derived from an exciter waveform induced in an artery transmitted therethrough. The pairs of exciters and sensors are arranged on a substrate in various formations. A/D converters are provided to respective detection signals. A frequency of the oscillation signal supplied to the exciter is controlled by various oscillation signal generation circuits. Bandpass filtering for extracting the exciter waveform, low-pass-filtering for extracting a natural blood pressure waveform, phase difference detection processes are provided by a microprocessor, wherein the bandpass filtering and low-pass-filtering processes may be replaced with a bandpass filter and a low pass filter, and their outputs are selected by a switching circuit and supplied to the microprocessor through one a/d converter. The frequency of the oscillation signal is controlled to an optimum frequency by detecting the detection signal and estimating the attenuation, dispersion, phase shift with respect to different frequency and by determining one of the different frequency in accordance with the estimation result. The waveform of the oscillation signal is controlled to an optimum waveform similarly.

Noninvasive continuous blood pressure measuring apparatus and a method of noninvasively measuring continuous blood pressure

A physical parameter measuring system is provided which measures a physical parameter such as a blood pressure of a person using oscillation transmission. The system includes a phase detector, an A/D converter, an arc center determining circuit, and a phase angle determining circuit. The phase detector detects a phase of a sensor signal produced, in sequence, by monitoring oscillations which are applied by an exciter and transmitted through a living body to map the signal on a two-dimensional plane as a sample point. The A/D converter converts the sample point signal into a digital sample point signal in sequence. The arc center determining circuit determines a center of an arc defined by a distribution of the sample points mapped for a given period of time. The arc determining circuit selects the sample points which are located at an interval greater than a given reference sample-to-sample distance to form a sample group consisting of at least three of the selected sample points and determines a center of a circle passing through the sample group as the center of the arc. The phase angle determining circuit determines a phase angle of the sample point as viewed from the arc center determined by the arc center determining circuit and provides it as a parameter used to determine a physical parameter of the subject.

System for measuring physical parameter utilizing vibration transmission

A blood pressure determining apparatus is provided which applies oscillations to the blood vessel of a subject through an exciter to determine the blood pressure based on the frequency of the oscillations propagated through the blood vessel measured by an oscillation sensor. The apparatus monitors an output of the oscillation sensor when the exciter applies no oscillation to the subject to determine the power spectrum of noise signals contained in the output and sets the frequency of oscillations to be applied to the blood vessel to any value within a band of the power spectrum in which the power of noise is small. This enables the blood pressure to be determined without influence of any electric disturbances from peripheral devices.

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Yokohama, Japan

Yushi Nishimura