JP2011050604A - Biological information measuring system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biological information measuring system which enables desired information relating to a subject to be obtained by obtaining a phase difference while properly adjusting the level of a signal based on a reflected wave reflected by the surface of the subject of microwaves applied to the subject so as to avoid influence of noise accompanying a movement of the subject not subjected to measurement. <P>SOLUTION: A reflected wave signal including a noise component obtained by a microwave transmission and reception unit 11 is subjected to adjustment of fixing the level of a reflected wave signal by an adjustment unit 12. Variation in amplitude component in an in-phase component signal and an orthogonal component signal obtained by a quadrature detection unit 13 is suppressed to eliminate an influence of the variation in the amplitude component on the calculation of a phase difference by an arithmetic unit 14. Accordingly, a phase difference signal properly corresponding to the micromotion of an object to be measured is obtained efficiently. Using the phase difference signal, the states of heart rate, respiration, or the like are measured appropriately and the state of the subject is evaluated appropriately. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a biological information measurement system that obtains a signal capable of analyzing the state of a subject based on a reflected wave obtained by irradiating the subject with microwaves.

  A technique for irradiating a measurement object with an electromagnetic wave and using the Doppler shift of the electromagnetic wave reflected by the measurement object to obtain the vibration state and displacement of the measurement object has been widely known. The electromagnetic wave has the property of transmitting through a medium such as a dielectric, and by using these, it is attempted to detect the heart beat and respiratory dynamics that appear as vibrations in the human body by microwave irradiation to the human body. Attempts have been proposed in recent years. By using the microwave, it is possible to perform measurement without touching the human body and wearing clothes, and an effect of minimizing the burden on the measurement subject can be obtained.

  This measurement system using microwaves is not limited to monitoring the health status of people in their daily lives, such as simply measuring heart rate and respiration rate, but also in the human body such as sleep apnea syndrome and sleep detection when driving a vehicle. It is also possible to find abnormalities and apply them to stress assessment based on heart rate measurements. In addition, it can be expected to be applied to security measures such as intruder monitoring due to the characteristics of being able to measure human movements from a remote location without contact.

  As an example of a measurement system using such a microwave, there are those disclosed in Japanese Patent Application Laid-Open Nos. 2002-58659 and 2009-55997.

JP 2002-58659 A JP 2009-55997 A

  Conventional measurement systems using microwaves are those described in the above-mentioned patent documents, and each has a mechanism for detecting minute movements of a subject using microwaves and obtaining information such as heartbeats. Specifically, by detecting the phase change (phase difference) of the reflected wave with respect to the irradiation wave, it is intended to detect microtremors on the body surface based on the vibration of the subject to be measured, such as the subject's heartbeat. For detection, quadrature detection (I-Q detection) as shown in Patent Document 2 is used. In quadrature detection, theoretically, the phase change can be efficiently calculated by separating the amplitude component and the phase change component of the reflected wave, but in a state that is not particularly restricted, such as a living body, When the subject is always subject to some kind of movement, the movement outside of the measurement becomes noise, and the amplitude component in the reflected wave changes greatly, and this large change in amplitude component detects the phase change. The phase component cannot be calculated as a correct response to the movement (fine movement) of the biological measurement target, and the obtained phase change is effectively used to indicate the movement of the measurement target such as heartbeat or respiration. I had a problem that I couldn't.

  The present invention has been made in order to solve the above-mentioned problems, and obtains the phase difference while appropriately adjusting the level of the signal based on the reflected wave of the microwave irradiated to the subject on the surface of the subject. It is an object of the present invention to provide a biological information measurement system that avoids the influence of noise associated with movement outside the measurement target and can appropriately grasp desired information on the subject.

  The biological information measurement system according to the present invention irradiates a non-stationary subject with microwaves, receives a reflected wave on the subject surface of the irradiated wave, and receives a reflected wave signal and a quadrature detection reference wave. A microwave transmission / reception unit that outputs a signal, an adjustment unit that adjusts a signal output level to obtain a reflected wave signal of a predetermined output level for a reflected wave signal output from the microwave transmission / reception unit, and the adjustment unit A quadrature detection unit that performs quadrature detection processing using the reflected wave signal and the reference wave signal, and obtains a signal of the in-phase component and a quadrature component of the reflected wave, and the in-phase component signal output from the quadrature detection unit and An arithmetic unit that calculates a phase difference signal between the irradiation wave and the reflected wave from the orthogonal component signal is provided.

  As described above, according to the present invention, the reflected wave signal including the noise component accompanying the movement of the subject other than the movement component of the measurement target obtained by the microwave transmission / reception unit is excluded from the measurement target of the subject by the adjustment unit. After performing the adjustment to make the level of the reflected wave signal that is greatly changed under the influence of the movement constant, the quadrature detection unit obtains the in-phase component signal and the quadrature component signal, and the in-phase component signal and the quadrature component signal By suppressing the change of the amplitude component and eliminating the influence of the change of the amplitude component on the calculation of the phase difference in the calculation unit, the reflected wave signal obtained by the microwave transmitting / receiving unit can be obtained by the quadrature detection process including the noise component. Even if the amplitude component of each signal is changed greatly and the phase difference cannot be calculated normally as it is, the phase difference can be calculated without the influence of noise and It is possible to efficiently obtain a phase difference signal that appropriately corresponds to the movement, and by using this phase difference signal, it is possible to correctly measure the state of heartbeat, respiration, etc. that appear as fine movements on the body surface, and to accurately evaluate the state of the subject. .

  Further, in the biological information measuring system according to the present invention, the microwave transmission / reception unit generates an irradiation antenna for irradiating the subject with microwaves and a microwave irradiated from the irradiation antenna as necessary. One microwave oscillator, a second microwave oscillator that generates another microwave having a predetermined frequency difference from the microwave, and the reference wave signal having a difference frequency from two microwaves generated by each microwave oscillator. A reference wave mixer unit to be obtained, a receiving antenna for receiving the reflected wave, a reflected wave for obtaining the reflected wave signal having a difference frequency from the reflected wave received by the receiving antenna and the microwave from the second micro oscillator And a mixer section for use.

  As described above, according to the present invention, the microwave transmission / reception unit is a heterodyne transmission / reception mechanism that uses another oscillator with a predetermined frequency difference for generating a reference wave signal, in addition to the irradiation microwave oscillator. By using two microwave oscillators, the reflected wave signal and reference wave signal can be converted to intermediate frequency signals, and the measurement accuracy can be improved by suppressing the frequency band of each signal, and the signal level can be adjusted. It is not necessary to consider the amplification of the DC component in the adjustment part when performing, and the system configuration can be simplified.

  In addition, the biological information measurement system according to the present invention includes offset adjusting means for adjusting the DC component in the in-phase component signal and the quadrature component signal output from the quadrature detection unit to 0 as necessary. .

  As described above, according to the present invention, the reflected wave signal obtained by the microwave transmission / reception unit is adjusted to the movement of the living body by adjusting the DC component in the in-phase component signal and the quadrature component signal obtained by quadrature detection to zero. Even in situations where there is a lot of accompanying noise and a large amount of DC component, and the DC component is larger than the amplitude component and affects the calculation, the calculation of the living body is performed by avoiding the influence of the DC component and accurately performing processing such as calculation. The phase difference signal corresponding to the target movement can be acquired, and the movement of the measurement target can be correctly evaluated.

  Further, in the biological information measurement system according to the present invention, as necessary, the calculation unit adjusts the DC component in the in-phase component signal and the quadrature component signal output from the quadrature detection unit to 0, The phase difference signal is obtained from the in-phase component signal and the quadrature component signal.

  As described above, according to the present invention, the reflected wave signal obtained by the microwave transmission / reception unit is converted into a living body by performing the adjustment so that the DC component in the in-phase component signal and the quadrature component signal obtained by quadrature detection is zero. Even in the situation that includes a lot of noise accompanying the movement of and contains a lot of DC components, and the DC component is larger than the amplitude component and affects the calculation, avoid the influence of the DC component and execute processing such as calculation accurately, A phase difference signal corresponding to the movement of the living body can be acquired, and the movement of the measuring object can be correctly evaluated.

  Moreover, the biological information measuring system according to the present invention includes at least two microwave transmission / reception units, the adjustment unit, and the quadrature detection unit as necessary, and subjects in two microwave transmission / reception units. The microwave irradiation and the reception of the reflected wave are performed at locations facing each other across the subject, and the two phase difference signals calculated from the in-phase component signal and the quadrature component signal for each system are added, The added signal is used as a phase difference signal for the entire system.

  Thus, according to the present invention, the microwave transmission / reception unit, the adjustment unit, and the quadrature detection unit are arranged in two systems, and the microwave irradiation and the reception of the reflected wave are opposed to the subject across the subject. The two phase difference signals calculated for each system are added together to obtain the overall phase difference signal, which is opposite to the reflected wave signal obtained at each position as the subject moves. By canceling the noise component superimposed on the phase, the reflected wave signal obtained by each microwave transmitter / receiver contains a lot of noise due to the movement of the subject outside the measurement target, and in the case of processing in a single system, the noise Even if the phase difference signal cannot be appropriately matched to the movement of the measurement target due to the influence of the noise, the phase difference signal is obtained and synthesized by the two systems to cancel the noise superimposition on the signal and ensure noise Figure of reduction , Is made to correspond to the motion to be measured reliably in vivo the phase difference signal, the condition of the subject appears as the motion of the measuring object can be correctly evaluated.

  Moreover, the biological information measuring system according to the present invention includes at least two microwave transmission / reception units, the adjustment unit, and the quadrature detection unit as necessary, and subjects in two microwave transmission / reception units. Microwave irradiation and reflected wave reception are performed at two different locations, and the cross-correlation between two phase difference signals calculated from the in-phase component signal and quadrature component signal for each system is obtained. A function signal is acquired, and the signal of the cross-correlation function is used as a phase difference signal of the entire system.

  As described above, according to the present invention, the microwave transmission / reception unit, the adjustment unit, and the quadrature detection unit are arranged in two systems, and the microwave irradiation and the reception of the reflected wave are performed on the subject at two different locations. Using the fact that the two phase difference signals calculated for each of them contain a waveform component that corresponds to the movement of the measurement object, the two phase difference signals are cross-correlated and the obtained cross-correlation function is updated. Therefore, the cross-correlation function that indicates the level of correlation between the two phase difference signals is a time function that matches the waveform component corresponding to the movement of the measurement target, and each microwave transceiver unit The cross-correlation function is measured even if the resulting reflected wave signal contains noise and the phase difference signal cannot be appropriately matched to the movement of the measurement target due to the influence of noise when processing in a single system. Movement Appropriately used as the corresponding phase difference signal, can eliminate the influence of noise from the phase difference signal and reliably correspond to the movement that is the measurement target of the living body, and can correctly evaluate the state of the subject that appears as the movement of the measurement target .

1 is a block configuration diagram of a biological information measurement system according to a first embodiment of the present invention. It is explanatory drawing of the offset adjustment principle based on the Lissajous figure and the signal output level adjustment principle of the biological information measuring system which concerns on the 1st Embodiment of this invention. It is another block block diagram of the biometric information measurement system which concerns on the 1st Embodiment of this invention. It is a block block diagram of the biological information measuring system which concerns on the 2nd Embodiment of this invention. It is a block block diagram of the biological information measurement system which concerns on the 3rd Embodiment of this invention. It is a graph which shows the graph of the in-phase component signal and quadrature component signal which were obtained by the quadrature detection process in Example 1 of the biometric information measurement system of this invention, and a phase difference signal. It is a graph of the Lissajous curve based on the in-phase component signal and quadrature component signal in Example 1 of the biological information measurement system of the present invention. It is wavelet conversion result explanatory drawing of the phase difference signal in case of AGC presence in Example 1 of the living body information measurement system of the present invention, and a graph of heart rate change based on Wavelet conversion and heart rate change based on an electrocardiograph. It is a wavelet conversion result explanatory drawing of the phase difference signal in the case of no AGC in Example 1 of the living body information measurement system of the present invention, and a graph of heart rate change based on Wavelet conversion and heart rate change based on an electrocardiograph. It is the graph which shows the phase difference signal of the system 1 in Example 2 of the biological information measuring system of this invention, and the graph which shows the phase difference signal of the system 2. It is a graph which shows the phase difference signal of the whole system in Example 2 of the biometric information measurement system of this invention. It is a graph of the Lissajous curve based on the in-phase component signal and quadrature component signal of the system 1 in Example 2 of the biological information measurement system of the present invention, and the graph of the Lissajous curve based on the in-phase component signal and quadrature component signal of the system 2. It is the power spectrum figure of the phase difference signal of the system 1 in Example 2 of the biometric information measurement system of this invention, and the power spectrum figure of the phase difference signal of the system 2. It is each power spectrum figure of the heart rate signal obtained with the phase difference signal of the whole system in Example 2 of the biological information measurement system of this invention, and an electrocardiograph. It is a graph which shows the graph of the in-phase component signal and quadrature component signal which were obtained by the quadrature detection process of the system 1 in Example 3 of the biological information measurement system of this invention, and a phase difference signal. It is a graph which shows the graph of the in-phase component signal and quadrature component signal which were obtained by the quadrature detection process of the system 2 in Example 3 of the biological information measurement system of this invention, and a phase difference signal. It is the graph of the Lissajous curve based on the in-phase component signal and quadrature component signal of the system 1 in Example 3 of the biological information measuring system of the present invention, and the graph of the Lissajous curve based on the in-phase component signal and quadrature component signal of the system 2. It is the graph which shows the cross correlation function of the phase difference signals of each system in Example 3 of the biological information measurement system of this invention, and the graph which expanded this in the time-axis direction. Respective power spectrum diagrams of the phase difference signal of the system 1 and the heart rate signal obtained by the electrocardiograph in Example 3 of the biological information measuring system of the present invention, and the heart rate signal obtained by the phase difference signal of the system 2 and the electrocardiograph FIG. It is each power spectrum figure of the heart rate signal obtained with the phase difference signal of the whole system in Example 3 of the biometric information measurement system of this invention, and an electrocardiograph.

(First embodiment of the present invention)
Hereinafter, a biological information measurement system according to a first embodiment of the present invention will be described with reference to FIG. 1 and FIG. In the present embodiment, an example of a measurement system for detecting a heartbeat by measuring the vibration of the heartbeat in a non-contact and unrestrained state will be described.

  In each of the drawings, the biological information measuring system 1 according to the present embodiment irradiates a subject 50 in a non-stationary state with a microwave, receives a reflected wave on the surface of the subject 50, and detects a reflected wave signal and quadrature detection. A microwave transmission / reception unit 11 that outputs a reference wave signal for use, an adjustment unit 12 that adjusts the signal output level of the reflected wave signal output from the microwave transmission / reception unit 11, and a reflected wave that is adjusted by the adjustment unit 12 A quadrature detection unit 13 that performs quadrature detection processing using the signal and the reference wave signal to obtain a signal having the same phase component and a quadrature component as the reflected wave; and the in-phase component signal and the quadrature component output from the quadrature detection unit 13 It is the structure provided with the calculating part 14 which calculates the phase difference signal of an irradiation wave and a reflected wave from a signal.

  The microwave transmission / reception unit 11 irradiates a human body as the subject 50 with continuous microwaves over a predetermined measurement time, while receiving a reflected wave of the irradiation wave on the surface of the subject 50 and measuring the human body. A reflected wave signal and a reference wave signal for obtaining a phase difference signal corresponding to a fine movement of the body surface based on the movement of the object, for example, heart beat or respiration are output.

  Specifically, the microwave transmission / reception unit 11 includes an irradiation antenna 11a that irradiates the subject 50 with microwaves, a first microwave oscillator 11b that generates microwaves irradiated from the irradiation antenna 11a, and a reflected wave. Receiving antenna 11c, a directional coupler 11d for separating the microwave generated by the first microwave oscillator 11b into an irradiation wave to the subject and a reference wave component, and a predetermined frequency difference from the microwave. A second microwave oscillator 11e that generates another microwave, and a directional coupler that separates the other microwave generated by the second microwave oscillator 11e into a reflected wave signal generating component and a reference wave signal generating component 11f and a reference wave signal for obtaining a reference wave signal having a difference frequency (intermediate frequency) from two reference microwaves separated by the directional couplers 11d and 11f. A configuration including a synthesizer unit 11g, and a reflected wave mixer unit 11h that obtains a reflected wave signal having a difference frequency (intermediate frequency) from the reflected wave received by the receiving antenna 11c and another microwave that has passed through the directional coupler 11f. It is.

  In the microwave transmitting and receiving unit 11, using two oscillators in the first microwave oscillator 11b and a second microwave oscillator 11e, microwaves and output from the reflected wave and the second microwave oscillator 11e in a subject 50 surface Is mixed in the mixer section to obtain a reflected wave signal converted into an intermediate frequency, and the reflected wave signal is mixed in the mixer section with each microwave output of the first microwave oscillator 11b and the second microwave oscillator 11e. The heterodyne method is used for outputting together with the intermediate frequency reference wave signal obtained in this way. A band of a filter such as a band-pass filter (band-pass filter) that is inserted into each signal line and attenuates unnecessary components by using two microwave oscillators and having the reflected wave signal and the reference wave signal as intermediate frequencies. The width can be narrowed, thereby eliminating the influence of unnecessary components such as harmonics in each signal and improving the measurement accuracy.

  Further, since the microwave transmission / reception unit 11 outputs the reflected wave signal and the reference wave signal converted into intermediate frequencies by the heterodyne method, the adjustment unit 12 in the subsequent stage does not need to consider the amplification of the DC component, so-called A DC amplifier configuration is not required, and a time-stable device configuration can be obtained in which the stability of the system can be easily maintained without being affected by drifts such as temperature changes.

  The adjusting unit 12 adjusts the signal output level of the reflected wave signal output from the microwave transmitting / receiving unit 11 to obtain a reflected wave signal in a predetermined output range. In detail, the gain variable amplifier and the detection control unit comprising a detection by the detection control unit output from the gain variable amplifier monitors and controls the gain of the variable gain amplifier to have a constant output which is set in advance, to perform a so-called AGC (automatic gain control) configuration It has become.

  Reflected wave signal adjusted to a predetermined output level in the adjusting portion 12 is input to the quadrature detector 13 with the reference wave signal from the mixer portion 11g reference wave, so that the quadrature detection processing is performed. In addition to the adjustment based on the output from the gain variable amplifier, the adjustment unit 12 includes the adjustment unit 14 so that the amplitude components of the in-phase component signal and the quadrature component signal input to the calculation unit 14 are in an appropriate range. It is also possible to send a control instruction to the adjustment unit 12 to adjust the signal output level.

  By adjusting the output level of the reflected wave signal to be constant by the adjustment unit 12, the amplitude component in the in-phase component signal and the quadrature component signal obtained by the subsequent quadrature detection unit 13 is not greatly changed. The calculation of the phase change is not affected by the change of the amplitude component, and an appropriate value can be obtained.

  The setting of the target value for making the output level of the reflected wave signal constant in the adjustment unit 12 is set so as not to saturate the input, for example, according to the input characteristics of the device such as the calculation unit 14 on the rear stage side. quadrature output from the detector 13 may be varied dynamically in response to changes in the reference while measuring conditions the magnitude of the amplitude component of the in-phase component signal and quadrature component signal handled by the calculation unit 14.

  Further, the output level of the reference wave signal may be adjusted in accordance with the output level of the reflected wave signal from the adjustment unit 12 so that the processing by the quadrature detection unit 13 is facilitated.

  The quadrature detection unit 13, a reflected wave signal adjusted by the adjustment unit 12 performs quadrature detection processing by using the reference wave signal outputted from the microwave transmitting and receiving unit 11, resulting in a general microwave receiver circuit A signal having an in-phase component and a signal having a quadrature component with respect to the reflected wave signal are obtained.

The quadrature detector 13 performs quadrature detection processing by demodulating the reference wave signal (A cos ωt) and the reflected wave signal (B cos (ωt + Δφ)) in combination, thereby orthogonal to the in-phase component signal (E _r cos Δφ) of the phase change. The component signal (E _r sin Δφ) can be obtained, and by obtaining these two signals, the arithmetic unit 14 can separate the amplitude component E _r and the phase difference component Δφ and obtain the phase difference signal by an easy calculation process. . The amplitude component _Er is the product of the amplitude A of the reference wave signal and the amplitude B of the reflected wave signal.

  Further, the quadrature detection unit 13 also has a function as the offset adjusting means, and can perform adjustment to set the DC component output together with the in-phase component signal and the quadrature component signal to zero in the quadrature detection processing of the reflected wave signal. It is. This offset adjustment can be easily performed using a differential amplifier on a detection circuit, a double balanced mixer (DBM), or the like.

The calculation unit 14 is configured to acquire (calculate) a phase difference signal (a component that is directly proportional to the phase change) between the irradiation wave and the reflected wave from the in-phase component signal and the quadrature component signal output from the quadrature detection unit 13. It is. Specifically, using the in-phase component signal (E _r cos Δφ) and the quadrature component signal (E _r sin Δφ) of the phase change Δφ obtained by the quadrature detector 13,
Δφ = tan ⁻¹ (E _r sin Δφ / E _r cos Δφ)
From this relationship, a component directly proportional to Δφ can be calculated, and a phase difference signal can be acquired.

  The computing unit 14 is a computer having a CPU, a memory, an input / output interface, and the like as its hardware configuration, and is a mechanism that causes the computer to operate as the computing unit 14 by a program stored in the memory or the like. The computer constituting the calculation unit 14 may be a microcomputer integrally formed with a CPU, a memory, a ROM, and the like.

The calculation unit 14 can also perform offset adjustment processing for setting the DC component of the in-phase component signal and the quadrature component signal to 0. As a specific technique for the offset adjustment, for example, the in-phase component signal (E _r cos Δφ) and quadrature component signal (E _r sin Δφ) where x = E _r cos Δφ and y = E _r sin Δφ, the change of each value is plotted on the xy plane, and the obtained curve (Lissajous figure) is a circle The center of the circle can be defined as a part, and an adjustment process can be performed to match the center of the circle with the origin of the xy plane (see FIG. 2A). By using the adjusted in-phase component signal and quadrature component signal, the phase difference signal can be calculated more appropriately.

  Even when the adjustment unit 12 adjusts the signal output level based on the magnitudes of the amplitude components of the in-phase component signal and the quadrature component signal input to the calculation unit 14, the calculation unit 14 similarly uses the in-phase component signal. The change of the value of the signal and the quadrature component signal is plotted on the xy plane, and the obtained curve (Lissajous figure) is a plurality of quadrants among the first to fourth quadrants of the xy plane, preferably three or more The signal output level can be adjusted by the adjustment unit to such an extent that the amplitude components of the in-phase component signal and the quadrature component signal are provided so as to extend over the quadrant (see FIG. 2B). As in the case, the phase difference signal can be calculated more appropriately using the adjusted in-phase component signal and quadrature component signal.

  Next, the usage state of the biological information measurement system according to the present embodiment will be described. As a premise, the person (subject) who becomes the subject 50 is located near the irradiation antenna 11a and the receiving antenna 11c, and the subject 50 is not restrained and moves (non-stationary state). It shall be.

  First, for a measurement time (for example, 30 seconds) set in advance for a human body as the subject 50, the microwave transmission / reception unit 11 applies irradiation to the continuous microwave generated by the first microwave oscillator 11b. While irradiating the subject 50 from the antenna 11a, the reflected wave on the body surface of the subject 50 is received by the receiving antenna 11c.

  The microwave transmitting / receiving unit 11 generates an intermediate frequency from the reflected wave received by the receiving antenna 11c and the other microwave generated by the second microwave oscillator 11e and passing through the directional coupler 11f by the reflected wave mixer unit 11h. The reflected wave signal is obtained. Further, from the same microwave as the irradiation wave generated by the first microwave oscillator 11b and passing through the directional coupler 11d, and another microwave generated by the second microwave oscillator 11e and passed through the directional coupler 11f, A reference wave signal having an intermediate frequency is obtained by the reference wave mixer 11g. Of the obtained signals, the reflected wave signal is input to the adjustment unit 12, and the reference wave signal is input to the quadrature detection unit 13.

The reflected wave signal output from the microwave transmitting / receiving unit 11 is adjusted to a predetermined output level by the AGC by the adjusting unit 12 and then input to the quadrature detecting unit 13. As the quadrature detection process, the quadrature detection unit 13 mixes and demodulates the reference wave signal (Acosωt) and the reflected wave signal (Bcos (ωt + Δφ)), and in-phase component signal (E _r cosΔφ) of the reflected wave and the quadrature component signal (E _r sin Δφ) is obtained. The in-phase component signal and the quadrature component signal are input to the calculation unit 14, and the calculation unit 14 generates a phase difference signal (component directly proportional to the phase change) between the irradiation wave and the reflected wave from the in-phase component signal and the quadrature component signal. Calculated.

  In the calculation of the phase difference Δφ at the operation unit 14, the amplitude of the pre-output level of the reflected wave signal by the adjustment section 12 that is adjusted to a constant phase component signal and quadrature component signal obtained by the quadrature detection section 13 The component does not change greatly, and the calculation of the phase difference in the calculation unit 14 is not affected by the change of the amplitude component, and an appropriate value corresponding to the movement of the measurement target in the subject 50 can be obtained. .

  The phase difference signal between the irradiation wave and the reflected wave represents the movement of the body surface based on the heartbeat, and each peak in the phase difference signal can be regarded as a peak corresponding to the heartbeat of the measurement target, and the heartbeat interval measurement It becomes possible to use for the use etc. If the fluctuation of the peak interval of the phase difference signal corresponding to the heartbeat interval is obtained, for example, stress evaluation can be performed. That is, the time change of the heartbeat interval read from the R wave and the R wave peak interval of the electrocardiograph is subjected to frequency analysis, and the peak value LF of the low frequency component and the peak value HF of the high frequency component are used as stress evaluation values. as with conventional stress evaluation method of obtaining the value of LF / HF, it can stress evaluation based on beat-to-beat variation with a peak interval of the phase difference signal, especially in the case of the system of the present embodiment, direct contact with the subject's body By performing the measurement without performing the measurement, the interval between heartbeats can be reliably captured without giving tension to the subject, and the stress evaluation can be appropriately performed and the evaluation accuracy can be improved.

  As described above, the biological information measurement system according to the present embodiment uses the adjustment unit 12 for the reflected wave signal including the noise component accompanying the movement of the subject other than the vibration component to be measured obtained by the microwave transmission / reception unit 11. After performing the adjustment to make the level of the reflected wave signal greatly changing under the influence of the movement of the subject outside the measurement target constant, the quadrature detection unit 13 obtains the in-phase component signal and the quadrature component signal, Since the change of the amplitude component in the in-phase component signal and the quadrature component signal is suppressed and the influence of the change in the amplitude component on the calculation of the phase difference in the calculation unit 14 is eliminated, the reflected wave signal obtained by the microwave transmitting / receiving unit 11 is a noise component. Even if the amplitude component of each signal obtained by the quadrature detection process is greatly changed and the phase difference cannot be calculated normally as it is, The phase difference can be calculated efficiently without the influence of noise, and the phase difference signal corresponding to the fine movement of the measurement target can be obtained efficiently. Using this phase difference signal, the state of heartbeat, breathing, etc. Can measure correctly and accurately assess the condition of the subject.

  In the living body information measurement system according to the embodiment, the microwave transmission / reception unit is configured to be a heterodyne system in which two microwave oscillators are provided. However, the present invention is not limited to this, and as illustrated in FIG. using the oscillator 15 only one, high-frequency oscillator 16, a power divider 17, and up-converter 18 in combination with a can also be configured using a heterodyne to generate a radiation wave and reference wave, the two microwave oscillators The stability at the time of use is obtained by superimposing the fluctuations of both, whereas when this up-converter 18 is used, the stability is determined by the fluctuation of only the high-frequency oscillator 16, so that the fluctuation component is It can be made extremely small, and the phase measurement accuracy can be improved. In addition to this heterodyne method, a reflected wave and a reference wave based on the same microwave oscillator output can be generated, and a homodyne method used for phase difference detection can be adopted, and only one microwave oscillator is required. The problem of stability of the oscillator frequency can be avoided.

  Further, in the biological information measurement system according to the embodiment, the measurement target is a heartbeat, a phase difference signal corresponding to the fine movement of the body surface based on the heartbeat is obtained from the reflected wave on the body surface, and the interval between the heartbeats is adjusted. Although it is configured to be obtained in the form of the peak interval of the phase difference signal, it is not limited to this, and it can be configured to measure the timing of breathing in addition to the heartbeat, and the breathing interval is set as the peak interval of the phase difference signal By being required, for example, stress evaluation from breathing can be performed. That is, breathing tends to be shallower and faster when stressed, deeper and slower when relaxed, and the phase difference signal has a lower amplitude and higher frequency during stress based on breathing, and an amplitude when relaxed. Since a vibration waveform component having a large frequency and a low frequency is included, an appropriate stress evaluation can be performed from the measured respiration. Simultaneous measurement of heart rate and respiration is also possible. In this case, stress evaluation can be performed from both sides of heart rate and respiration change, and respiration that is closely related to stress as well as heart rate is analyzed and compared. By performing stress evaluation in parallel with stress evaluation by heart rate measurement, the accuracy and reliability of the evaluation are improved. In addition, the relationship between heart rate variability and respiratory variability in stress evaluation can be clarified.

(Second embodiment of the present invention)
A second embodiment of the present invention will be described with reference to FIG. Also in this embodiment, an example of a measurement system for detecting a heartbeat by measuring the vibration of the heartbeat in a non-contact and unconstrained state will be described.

  In FIG. 4, the measurement evaluation system 2 according to the present embodiment includes two systems of microwave transmission / reception units 21 and 25, adjustment units 22 and 26, and quadrature detection units 23 and 27 similar to those of the first embodiment. From the in-phase component signal and quadrature component signal output from the quadrature detection units 23 and 27 of the system, the phase difference signal between the irradiation wave and the reflected wave is calculated for each system, and the obtained two phase difference signals are added. And a calculation unit 24 that executes processing to obtain a phase difference signal of the entire system.

  The microwave transmission / reception units 21 and 25 each output a reflected wave signal and a reference wave signal of an intermediate frequency with a heterodyne transmission / reception configuration similar to that of the first embodiment, and will not be described in detail. However, at least the irradiation antenna 21a and the reception antenna 21c of the one microwave transmission / reception unit 21 are disposed on the back side of the subject, and at least the irradiation antenna of the other microwave transmission / reception unit 25. 25a and receiving antenna 25c is provided on the front side of the subject and reception of microwave radiation and the reflected waves to a subject in the two microwave transmitting and receiving unit 21 and 25, and face each other across the subject It is a mechanism that is performed at each location. The frequency of the microwaves handled by the microwave transmitting / receiving units 21 and 25 is different for each microwave transmitting / receiving unit, and only the reflected wave of the irradiation wave from one irradiation antenna 21a is received by the reception antenna 21c. In addition, only the reflected wave of the irradiation wave from the other irradiation antenna 25a is received by the reception antenna 25c.

  The adjustment units 22 and 26 adjust the reflected wave signal to a constant signal output level as AGC, respectively, as in the first embodiment. The adjustment unit 22 is output from one microwave transmission / reception unit 21. The signal output level of the reflected wave signal is adjusted, and the adjusting unit 26 adjusts the signal output level of the reflected wave signal output from the other microwave transmitting / receiving unit 25.

  The quadrature detection section 23 and 27, in which each of the same first embodiment, performs a quadrature detection processing using the reference wave signal and reflected wave signal to obtain a signal of the signal and the orthogonal component of the reflected wave in phase component is there. Among these, one quadrature detection unit 23 performs quadrature detection processing using the reflected wave signal adjusted by the adjustment unit 22 and the reference wave signal output from the microwave transmission / reception unit 21, and detects the other quadrature detection. The unit 27 performs quadrature detection processing using the reflected wave signal adjusted by the adjusting unit 26 and the reference wave signal output from the microwave transmitting / receiving unit 25.

  The arithmetic unit 24 calculates a phase difference signal from the in-phase component signal and the quadrature component signal output from one quadrature detection unit 23 as in the first embodiment, and outputs from the other quadrature detection unit 27. The phase difference signal is calculated from the in-phase component signal and the quadrature component signal in the same manner as in the first embodiment, and the obtained phase difference signals for each of the two systems are added. This is a phase difference signal.

  As in the first embodiment, the calculation unit 24 is a mechanism that causes a computer as hardware to operate as the calculation unit 24 by a program. In addition, as with the microwave transmission / reception unit, the calculation unit is also arranged so that two different calculation units for each system calculate the phase difference signal, and the calculated entire phase difference signal is added. Another calculation unit for obtaining the phase difference signal may be newly provided.

  Next, the usage state of the biological information measurement system according to the present embodiment will be described. As a premise, the person (subject) who becomes the subject 50 is located between the group of one irradiation antenna 21a and the receiving antenna 21c, and the other group of the irradiation antenna 25a and the receiving antenna 25c, further, the subject 50 is in the situation where the motion has not been constrained occur (non-stationary state), it is assumed that moving further front side of the antenna 25a, to the direction that approaches gradually to 25c.

  First, with respect to the human body as a subject 50, a preset measuring time (e.g., 30 seconds), the microwave transmitting and receiving unit 21, subjects the microwave continuous caused by the first microwave oscillator 21b The subject 50 is irradiated from the rear-side irradiation antenna 21a, and the reflected wave on the body surface of the subject 50 is also received by the receiving antenna 21c on the rear side of the subject. The other microwave transmitting / receiving unit 25 irradiates the subject 50 with the continuous microwave generated by the first microwave oscillator 25b from the irradiation antenna 25a on the front side of the subject, and the body of the subject 50. Similarly, the reflected wave on the surface is received by the receiving antenna 25c on the front side of the subject.

  Microwave transceiver 21, a reflected wave in a subject back side received by the receiving antenna 21c, from other microwaves passing through the generated directional coupler 21f in the second microwave oscillator 21e, a mixer for the reflected wave A reflected wave signal having an intermediate frequency is obtained by the unit 21h. Further, from the same microwave as the irradiation wave generated by the first microwave oscillator 21b and passing through the directional coupler 21d, and another microwave generated by the second microwave oscillator 21e and passed through the directional coupler 21f, A reference wave signal having an intermediate frequency is obtained by the reference wave mixer unit 21g. Of the obtained signals, the reflected wave signal is input to the adjustment unit 22, and the reference wave signal is input to the quadrature detection unit 23.

  Similarly, the microwave transmission / reception unit 25 reflects the reflected wave on the front side of the subject received by the receiving antenna 25c and the other microwave generated by the second microwave oscillator 25e and passing through the directional coupler 25f. An intermediate frequency reflected wave signal is obtained by the wave mixer 25h. Further, from the same microwave as the irradiation wave generated by the first microwave oscillator 25b through the directional coupler 25d and the other microwave generated by the second microwave oscillator 25e and passed through the directional coupler 25f, A reference wave signal having an intermediate frequency is obtained by the reference wave mixer unit 25g. Of the obtained signals, the reflected wave signal is input to the adjustment unit 26, and the reference wave signal is input to the quadrature detection unit 27.

  The reflected wave signals output from the microwave transmission / reception units 21 and 25 are adjusted to predetermined output levels by the AGC by the adjustment units 22 and 26, respectively, and then input to the quadrature detection units 23 and 27. As the quadrature detection process, the quadrature detection unit 23 demodulates the reference wave signal from the microwave transmission / reception unit 21 and the reflected wave signal from the adjustment unit 22 and demodulates them, and outputs the in-phase component signal of the reflected wave on the back side of the subject. An orthogonal component signal is obtained. The in-phase component signal and the quadrature component signal are input to the calculation unit 24, and the calculation unit 24 calculates a phase difference signal between the irradiation wave and the reflected wave on the back side of the subject from the in-phase component signal and the quadrature component signal.

  On the other hand, the quadrature detection unit 27 demodulates the quadrature detection processing by combining the reference wave signal from the microwave transmitting / receiving unit 25 and the reflected wave signal from the adjustment unit 26, and in-phase components of the reflected wave on the front side of the subject. A signal and a quadrature component signal are obtained. These in-phase component signal and quadrature component signal are also input to the calculation unit 24, and the calculation unit 24 calculates a phase difference signal between the irradiation wave and the reflected wave on the front side of the subject from the in-phase component signal and the quadrature component signal.

  Further, the calculation unit 24 performs addition processing of the calculated phase difference signal on the subject front side and the phase difference signal on the subject rear side. In the phase difference signal calculated for each system, noise components accompanying the movement of the subject are superimposed, but microwave irradiation and reception of reflected waves are opposed to the subject across the subject. By being performed in two places, the noise components in the two reflected wave signals are in opposite phases to each other. By adding these two reflected wave signals, it is possible to cancel the noise components superimposed on the signals in opposite phases, and if the signal obtained by the addition is newly made the phase difference signal of the entire system, the body to be measured While the phase difference component corresponding to the fine movement in the table is emphasized, a phase difference signal in which noise associated with the movement of the subject outside the measurement target is suppressed is obtained.

  As described above, the biological information measurement system according to this embodiment includes the microwave transmission / reception units 21 and 25, the adjustment units 22 and 26, and the quadrature detection units 23 and 27. Wave irradiation and reception of reflected waves are performed at two locations facing each other across the subject, and the two phase difference signals calculated for each system are added to obtain the entire phase difference signal. Accordingly, since the noise component superimposed on the reflected wave signal obtained at each position in the opposite phase is canceled, the reflected wave signal obtained by each of the microwave transmitting / receiving units 21 and 25 is the movement of the subject outside the measurement target. In the case of processing in a single system that contains a lot of noise, the phase difference signal is obtained by two systems even if the phase difference signal cannot be appropriately matched to the movement of the measurement target due to the influence of noise. Together By canceling the noise superimposition on the signal, the noise can be reliably reduced, and the phase difference signal can be reliably matched to the movement to be measured by the living body, and the state of the subject appearing as the movement of the measurement target can be determined. Can be evaluated correctly.

  As an application of the biological information measurement system according to the embodiment, the distant two points of the dynamic lines of the doorway to the room, such as a building, and two systems disposed in an arrangement to be aligned toward the microwave transmitting and receiving unit, across the human By synthesizing each phase difference signal based on the reflected wave signal from the person in each system in the state, the heart rate change can be correctly evaluated and used for detecting a person in a tension state (for example, during suspicious behavior). Also, even when it is not necessary to determine the heart rate and its change, utilizing the fact that the phase change of the reflected wave due to the presence of a person is larger than the phase change caused by the fluctuation of the microwave oscillator and the fine movement of the surrounding environment, Since the presence of an intruder in the microwave irradiation range can be detected, the present invention can be applied to a security measure that requires contactless and remote monitoring of the intruder.

(Third embodiment of the present invention)
A third embodiment of the present invention will be described with reference to FIG. Also in this embodiment, an example of a measurement system for detecting a heartbeat by measuring the vibration of the heartbeat in a non-contact and unconstrained state will be described.

  5, the measurement evaluation system 3 according to the present embodiment includes two systems of microwave transmission / reception units 31 and 35, adjustment units 32 and 36, and quadrature detection units 33 and 37, as in the second embodiment. While the unit 34 has a configuration for calculating the phase difference signal of the irradiation wave and the reflected wave for each system from the in-phase component signal and the quadrature component signal output from the quadrature detection units 33 and 37 of each system, As described above, the calculation unit 34 obtains the cross-correlation between two phase difference signals calculated from the in-phase component signal and the quadrature component signal for each system, and obtains the signal of the cross-correlation function as the phase difference signal of the entire system. It is what you have.

  The microwave transmission / reception units 31 and 35 each output a reflected wave signal and a reference wave signal of an intermediate frequency with a heterodyne transmission / reception configuration similar to that of the first embodiment, and will not be described in detail. However, in one microwave transmission / reception unit 31, at least the irradiation antenna 31a and the reception antenna 31c are arranged at a predetermined first location facing the subject from a predetermined first direction, and the other In the microwave transmitting / receiving unit 35, at least the irradiation antenna 35a and the receiving antenna 35c are arranged at a second location different from the first location and face the subject from a predetermined second direction. The microwave irradiation and the reception of the reflected wave to the subject in the two microwave transmission / reception units 31 and 35 are respectively performed in two different places facing the subject from different directions. The microwave frequencies handled by these microwave transmitting / receiving units 31 and 35 are different for each microwave transmitting / receiving unit, and only the reflected wave of the irradiation wave from one irradiation antenna 31a is received by the reception antenna 31c. In addition, only the reflected wave of the irradiation wave from the other irradiation antenna 35a is received by the reception antenna 35c.

  As in the first embodiment, the adjustment units 32 and 36 adjust the reflected wave signal to a constant signal output level as AGC, and the adjustment unit 32 is output from one microwave transmission / reception unit 31. The signal output level of the reflected wave signal is adjusted, and the adjusting unit 36 adjusts the signal output level of the reflected wave signal output from the other microwave transmitting / receiving unit 35.

  The quadrature detection section 33 and 37, in which each of the same first embodiment, performs a quadrature detection processing using the reference wave signal and reflected wave signal to obtain a signal of the signal and the orthogonal component of the reflected wave in phase component is there. Among these, one quadrature detection unit 33 performs quadrature detection processing using the reflected wave signal adjusted by the adjustment unit 32 and the reference wave signal output from the microwave transmission / reception unit 31, and also detects the other quadrature detection. The unit 37 performs quadrature detection processing using the reflected wave signal adjusted by the adjusting unit 36 and the reference wave signal output from the microwave transmitting / receiving unit 35.

  The calculation unit 34 calculates a phase difference signal from the in-phase component signal and the quadrature component signal output from one quadrature detection unit 33 as in the first embodiment, and outputs from the other quadrature detection unit 37. After the phase difference signal is calculated from the in-phase component signal and the quadrature component signal as in the first embodiment, the cross-correlation between the obtained two phase difference signals for each system is obtained, and the cross correlation function is calculated. The entire phase difference signal is used.

  The mechanism for obtaining the cross-correlation function will be described. Since each phase difference signal includes a waveform component corresponding to the periodic fine movement to be measured, there is a strong correlation point between the signals, and the cross-correlation function It is expected that a periodic change close to the waveform component appears. On the other hand, since the noise component included in each phase signal is random in time, no correlation is obtained. Therefore, the cross-correlation function has a waveform component corresponding to the periodic fine movement to be measured while eliminating the influence of noise, and can be used as a new phase difference signal of the entire system.

  Here, when one calculated phase difference signal is A (t) and the other phase difference signal is B (t), the cross-correlation function C (τ) is defined by the following equation.

Here, A (t) on the right side represents one phase difference signal at a certain time t, and B (t + τ) represents the other phase difference signal when a predetermined time τ has elapsed from time t.

  As in the first embodiment, the calculation unit 34 is a mechanism that causes a computer as hardware to operate as the calculation unit 34 by a program. As with the microwave transmission / reception unit, etc., two calculation units are arranged so that different calculation units calculate the phase difference signal, and the calculated correlation between the phase difference signals is obtained. Alternatively, another calculation unit for obtaining a signal of the cross correlation function may be newly provided.

  Next, the usage state of the biological information measurement system according to the present embodiment will be described. Given, who becomes a subject 50 (subject) is a both-facing position with one of the irradiation antenna 31a and the group of the receiving antenna 31c, and the other irradiation antenna 35a and the group of the receiving antenna 35c In addition, it is assumed that the subject 50 is not restrained and is in a state (non-stationary state) in which movement occurs.

  First, for a human body as the subject 50, one microwave transmission / reception unit 31 generates a continuous microwave generated by the first microwave oscillator 31b for a preset measurement time (for example, 30 seconds). The subject 50 is irradiated from the irradiation antenna 31a, and the reflected wave on the body surface of the subject 50 is received by the receiving antenna 31c. Further, the other microwave transmitting / receiving unit 35 irradiates the subject 50 with the continuous microwave generated by the first microwave oscillator 35b from the irradiation antenna 35a, and the reflected wave on the body surface of the subject 50. Is received by the receiving antenna 35c.

  One microwave transmitter / receiver 31 receives a reflected wave from a reflected wave from the subject surface received by the receiving antenna 31c and another microwave generated by the second microwave oscillator 31e and passing through the directional coupler 31f. An intermediate frequency reflected wave signal is obtained by the mixer unit 31h. Further, from the same microwave as the irradiation wave generated by the first microwave oscillator 31b and passing through the directional coupler 31d, and another microwave generated by the second microwave oscillator 31e and passed through the directional coupler 31f, A reference wave signal having an intermediate frequency is obtained by the reference wave mixer unit 31g. Of the obtained signals, the reflected wave signal is input to the adjustment unit 32, and the reference wave signal is input to the quadrature detection unit 33.

  Similarly, the other microwave transmission / reception unit 35 includes a reflected wave from the subject surface received by the receiving antenna 35c and another microwave generated by the second microwave oscillator 35e and passing through the directional coupler 35f. Then, a reflected wave signal having an intermediate frequency is obtained by the reflected wave mixer unit 35h. Further, the same microwave as the irradiation wave generated by the first microwave oscillator 35b and passed through the directional coupler 35d, and another microwave generated by the second microwave oscillator 35e and passed through the directional coupler 35f, A reference wave signal having an intermediate frequency is obtained by the reference wave mixer unit 35g. Of the obtained signals, the reflected wave signal is input to the adjustment unit 36, and the reference wave signal is input to the quadrature detection unit 37.

  The reflected wave signals output from the microwave transmission / reception units 31 and 35 are adjusted to a predetermined output level by the AGC by the adjustment units 32 and 36, respectively, and then input to the quadrature detection units 33 and 37. As the quadrature detection process, the quadrature detection unit 33 demodulates the reference wave signal from the microwave transmission / reception unit 31 and the reflected wave signal from the adjustment unit 32, and in-phases the reflected wave in the first direction of the subject. A component signal and a quadrature component signal are obtained. The in-phase component signal and the quadrature component signal are input to the calculation unit 34, and the calculation unit 34 calculates a phase difference signal between the irradiation wave and the reflected wave in the first direction of the subject from the in-phase component signal and the quadrature component signal. To do.

  On the other hand, the quadrature detection unit 37 demodulates the quadrature detection processing by combining the reference wave signal from the microwave transmission / reception unit 35 and the reflected wave signal from the adjustment unit 36, and reflects the reflected wave in the second direction of the subject. In-phase component signal and quadrature component signal are obtained. These in-phase component signal and quadrature component signal are also input to the calculation unit 34, and the calculation unit 34 calculates a phase difference signal between the irradiation wave and the reflected wave in the second direction of the subject from these in-phase component signal and quadrature component signal. To do.

  Subsequently, the calculation unit 34 obtains a cross-correlation between the calculated phase difference signal in the first direction of the subject and the phase difference signal in the second direction of the subject, and calculates a cross-correlation function over the entire measurement time. obtain. The phase difference signals calculated for each system are superimposed with noise components that accompany the movement of the subject, but the phase difference signals that include both the waveform components corresponding to the fine movements to be measured are correlated to each other. By acquiring the correlation function, the signal waveform component corresponding to the fine movement to be measured is extracted, but the noise component having no correlation between the phase difference signals can be canceled. If the obtained cross-correlation function is newly used as the phase difference signal of the entire system, the phase difference component corresponding to the fine movement of the body surface to be measured is clarified, but the movement of the subject outside the measurement target is clarified. This means that a phase difference signal with suppressed noise is obtained.

  In this way, even when the reflected wave signals obtained by the microwave transmission / reception units 31 and 35 each contain a lot of noise, the cross-correlation function is obtained and used as a phase difference signal, so that the fine movement of the measurement object, that is, the heartbeat is measured. A corresponding phase difference signal can be obtained reliably.

  As described above, in the biological information measurement system according to the present embodiment, the microwave transmission / reception units 31 and 35, the adjustment units 32 and 36, and the quadrature detection units 33 and 37 are arranged in two lines, and microwave irradiation to the subject is performed. And receiving the reflected wave at two different locations, and using the fact that the two phase difference signals calculated for each system contain the waveform component corresponding to the movement of the measurement object in common, Since the cross-correlation of the signals is taken and the signal of the obtained cross-correlation function is used as a new overall phase difference signal, the cross-correlation function indicating the level of correlation between the two phase difference signals is A time change that matches the corresponding waveform component occurs, and the reflected wave signal obtained by each of the microwave transmitting / receiving units 31 and 35 includes noise, and is affected by the noise in the case of processing in a single system. Place Even if the difference signal cannot be appropriately matched to the movement of the measurement target, the cross-correlation function signal can be used appropriately as the phase difference signal corresponding to the movement of the measurement target, eliminating the influence of noise from the phase difference signal. Thus, the state of the subject that appears as the movement of the measurement target can be correctly evaluated by making it correspond to the movement of the measurement target of the living body.

In the biological information measurement system of the present invention, heartbeat measurement results by an electrocardiograph as a comparative example for each phase difference signal obtained by measuring microtremors on the body surface based on the heartbeat of the subject under a plurality of conditions Compared to the above, we evaluated the detectability of heartbeat by this system.
Example 1
As Example 1, using the biological information measurement system according to the first embodiment, microwaves are applied to the upper back of a non-stationary subject seated on a car seat, and the back side corresponding to the motion of the heart Body surface tremor was measured. The measurement was performed for both cases with and without AGC by the adjusting unit when the subject was driving on the highway. In the measurement, the irradiating antenna and the receiving antenna of the microwave transmitting / receiving unit were arranged using the horn antenna or the flat antenna, and arranged side by side on the seat rear side.

The microwave generated by the microwave oscillator has a frequency of 10 GHz and an irradiation intensity of 150 μW. This microwave is irradiated from the irradiation antenna through the directional coupler. On the other hand, in measurement of a living body, the value of the amplitude component _Er of each signal after quadrature detection processing changes greatly with the movement of the body in a non-stationary state, making it difficult to detect the phase difference. The adjustment unit uses AGC having a large control range (for example, 56 dB) in order to control such a change in the amplitude component _Er .

  The reflected wave on the subject's back is received by the receiving antenna, and when the reflected wave signal has AGC, it is input to the adjustment unit, adjusted to a constant output level, and then enters the quadrature detection unit. When the reflected wave signal is not AGC, it is directly input to the quadrature detection unit.

  The quadrature detection unit obtains the in-phase component signal and the quadrature component signal of the reflected wave, and further processes them by the computation unit to output a phase difference signal presumed to correspond to the fine movement of the body surface corresponding to the heartbeat. In the quadrature detection unit, offset adjustment is performed so that the DC components of the in-phase component signal and the quadrature component signal that are changed according to the measurement environment in the quadrature detection process are set to 0 in advance, and the influence of the measurement environment itself can be ignored.

  In addition, as a comparative example, heart rate measurement using an electrocardiograph was performed simultaneously with measurement using a microwave. The electrocardiograph electrodes were measured in direct contact with multiple locations of the subject's body in the same manner as in general electrocardiogram measurement.

  Both the example and the comparative example are measured under a situation where the subject and the measurement system are subjected to engine vibration, vibration accompanying road running, etc. in the automobile as a non-stationary environment, and the measurement time is 30 seconds. FIG. 6A shows an in-phase component signal and a quadrature component signal output from the quadrature detection unit based on the reflected wave signal in the embodiment. FIG. 6B shows the phase difference signal waveform calculated by the calculation unit.

In the case of AGC, the in-phase component signal (E _r cos Δφ) and the quadrature component signal (E _r sin Δφ) obtained by the quadrature detection processing are set on the xy plane as x = E _r cos Δφ and y = E _r sin Δφ. The change of each value is plotted, and the obtained Lissajous curve is shown in FIG. From FIG. 7, it can be seen that the center of the circle when the curve in the figure is regarded as a part of the circle is substantially coincident with the origin of the xy plane, and the phase difference is appropriately calculated by AGC in the adjustment unit. You can see the state that can be calculated in the section.

  Here, for each phase difference signal with and without AGC in the adjustment unit, signal wavelet conversion is performed in order to evaluate the detectability of the heartbeat. FIG. 8A shows the result of Wavelet conversion with AGC, and FIG. 9A shows the case without AGC. As a result of the wavelet transform, the time / frequency spectrum of the phase difference signal is displayed. In FIG. 8A, the vertical axis represents frequency values, the horizontal axis represents time, and the shading represents intensity. In FIG. 8A, it can be seen that a peak is observed at a frequency of about 1.1 Hz during a period of time 60 to 86 (s), and this peak changes little by little. The waveform of the temporal change of the peak that appears in this way, that is, the waveform of the temporal change of the instantaneous heart rate is extracted, and this waveform is compared with the waveform of the temporal change of the heart rate obtained from the electrocardiograph. The waveform of this heart rate change over time is shown in FIG. 8 (B), with a graph showing both the waveform based on the wavelet transform result of the phase difference signal and that obtained from the electrocardiograph of the comparative example. , No AGC is shown in FIG.

  As shown in FIG. 9B, in the case without AGC, the time change of the heart rate based on the Wavelet conversion result and the time change of the heart rate obtained from the electrocardiograph are greatly different from each other. In the case with AGC shown in FIG. 8 (B), it is not possible to say that the heart rate is properly captured by the measurement by, and the time change of the heart rate based on the Wavelet conversion result and obtained from the electrocardiograph The time change of the heart rate agrees well with an error of about 3%, and it can be seen that the heart rate can be measured with high accuracy even with microwaves. It is clear that the measurement accuracy is greatly improved when AGC is present compared to when AGC is not present.

(Example 2)
Next, as Example 2, using the biological information measurement system according to the second embodiment, microwaves are irradiated to the front and back of the subject in a non-stationary state to finely move the body surface corresponding to the motion of the heart. Was measured. Measurements were taken on subjects who were standing and moving back and forth.

  In the measurement, the microwave transmission / reception unit, the adjustment unit, and the quadrature detection unit are arranged in two systems, and from the in-phase component signal and the quadrature component signal output from the quadrature detection unit of each system, an irradiation wave and a reflected wave are calculated by the calculation unit. The phase difference signal is calculated for each system, and the obtained two phase difference signals are added to form a phase difference signal for the entire system. The irradiation antenna and reception antenna of each microwave transmission / reception unit use horn antennas, the irradiation antenna and reception antenna in one microwave transmission / reception unit are arranged on the back side of the subject, and the other microwave The irradiation antenna and reception antenna in the wave transmission / reception unit are arranged on the front side of the subject so that microwave irradiation to the subject and reception of reflected waves can be performed at opposite locations across the subject. . For convenience, the system of the irradiation antenna and the reception antenna disposed on the back side of the subject is referred to as system 1, and the system of the irradiation antenna and the reception antenna disposed on the front side of the subject is referred to as system 2.

  Moreover, the frequency of the microwave used in these microwave transmission / reception units is 9.7 GHz on the front side of the subject and 10 GHz on the back side. The irradiation intensity is 419 μW on the front side of the subject and 366 μW on the back side. On the other hand, the AGC characteristic in each adjustment unit, the output of the in-phase component signal and the quadrature component signal in the quadrature detection unit, and the calculation of the phase difference signal of each system in the calculation unit are the same as in the first embodiment under the same conditions.

  After calculating the phase difference signal for each system in the calculation unit, the calculation unit further adds the two phase difference signals, and is estimated to correspond to the fine movement of the body surface corresponding to the heartbeat. A signal is output.

  On the other hand, as a comparative example, heart rate measurement was also performed using an electrocardiograph simultaneously with measurement using a microwave. The electrocardiograph electrodes were measured in direct contact with multiple locations of the subject's body in the same manner as in general electrocardiogram measurement.

  Both the examples and comparative examples were measured while the subject was in a non-stationary state, and the measurement time was 30 seconds. FIG. 10A shows the phase difference signal waveform calculated by the calculation unit based on the reflected wave signal obtained by each microwave transmission / reception unit in the present embodiment, and FIG. ) Respectively. Further, FIG. 11 shows a phase difference signal waveform obtained by adding two phase difference signals in the calculation unit. However, the phase difference signal waveforms in the above figures are those after removing unnecessary frequency components (0.7 Hz or less) of the phase difference signal with a high-pass filter, and low frequency components including DC components are eliminated. The amplitude of the time waveform is distributed around 0.

In addition, for the in-phase component signal (E _r cos Δφ) and quadrature component signal (E _r sin Δφ) obtained by the quadrature detection process, the change of each value is plotted on the xy plane as x = E _r cos Δφ and y = E _r sin Δφ. The Lissajous curves obtained are shown in FIG. 12A for the system 1 and in FIG. 12B for the system 2, respectively.

  Then, for the phase difference signal obtained for each system of the embodiment and the phase difference signal as a whole system obtained by adding these, frequency analysis by fast Fourier transform is performed in order to evaluate the detectability of the heartbeat, The power spectrum for each frequency band was obtained and compared with the power spectrum obtained in the same manner from the electrocardiograph measurement results. Each power spectrum of the phase difference signal obtained on the subject back side (system 1) and the phase difference signal obtained on the subject front side (system 2) was added to FIGS. 13 (A) and 13 (B). FIG. 14 shows the power spectrum of the phase difference signal as a whole system together with that obtained from the electrocardiograph of the comparative example.

  As shown in FIG. 13, the power spectrum of the phase difference signal obtained for each system is greatly different from the power spectrum obtained from the measurement with the electrocardiograph (see FIG. 14). As shown in FIG. 14, the power spectrum of the phase difference signal of the entire system obtained by the addition is in good agreement with that from the electrocardiograph, and the heartbeat is detected by the electrocardiograph by the addition of the phase difference signal. It can be seen that the measurement can be performed with the same accuracy as the measurement.

(Example 3)
Subsequently, as Example 3, using the biological information measurement system according to the third embodiment, the back of a non-stationary test subject sitting on a car seat is irradiated with microwaves from two different locations, and the heart The tremor on the dorsal body surface corresponding to the movement of the back was measured. The measurement was performed on a subject when the automobile was stopped and in an idling state.

  In the measurement, the microwave transmission / reception unit, the adjustment unit, and the quadrature detection unit are arranged in two systems, and from the in-phase component signal and the quadrature component signal output from the quadrature detection unit of each system, an irradiation wave and a reflected wave are calculated by the calculation unit. The phase difference signal is calculated for each system, the cross-correlation between the two obtained phase difference signals is obtained, and the process of using the cross-correlation function signal as the phase difference signal of the entire system is executed. The irradiation antenna and the reception antenna of each microwave transmission / reception unit use a bow-tie antenna, and the irradiation antenna and the reception antenna in one microwave transmission / reception unit are arranged side by side at almost the middle height position of the seat back. In addition, the irradiation antenna and the receiving antenna in the other microwave transmission / reception unit are arranged side by side on the upper part of the back of the seat, and the microwave irradiation to the subject and the reception of the reflected wave are different from those of the subject. I was able to do it. For the sake of convenience, the system of the irradiation antenna and the receiving antenna disposed at almost the middle height position of the seat back portion is the system 1, and the system of the irradiation antenna and the receiving antenna disposed at the upper portion of the seat rear portion is shown. This is called system 2.

  Further, the microwave frequency used in these microwave transmission / reception units is 10 GHz in the system 1 and 9.7 GHz in the system 2. The irradiation intensity is 366 μW in the system 1 and 419 μW in the system 2. On the other hand, the AGC characteristic in each adjustment unit, the output of the in-phase component signal and the quadrature component signal in the quadrature detection unit, and the calculation of the phase difference signal of each system in the calculation unit are the same as in the first and second embodiments under the same conditions. It is.

  After calculating the phase difference signal for each system in the calculation unit, the calculation unit further obtains a cross-correlation between the two phase difference signals, obtains a cross-correlation function, and uses this as a tremor on the body surface corresponding to the heartbeat. It is output as a phase difference signal of the entire system, which is presumed to correspond.

  On the other hand, as a comparative example, heart rate measurement was also performed using an electrocardiograph simultaneously with measurement using a microwave. The electrocardiograph electrodes were measured in direct contact with multiple locations of the subject's body in the same manner as in general electrocardiogram measurement.

  Both the examples and comparative examples were measured while the subject was in a non-stationary state, and the measurement time was 30 seconds. FIG. 15A shows an in-phase component signal and a quadrature component signal output from the quadrature detection unit based on the reflected wave signal of the system 1 in this embodiment. FIG. 15B shows the phase difference signal waveform of the system 1 calculated by the calculation unit. On the other hand, the in-phase component signal and the quadrature component signal output from the quadrature detection unit based on the reflected wave signal of the system 2 are shown in FIG. Then, the phase difference signal waveform of the system 2 calculated by the calculation unit is shown in FIG.

In addition, for the in-phase component signal (E _r cos Δφ) and quadrature component signal (E _r sin Δφ) obtained by the quadrature detection process, the change of each value is plotted on the xy plane as x = E _r cos Δφ and y = E _r sin Δφ. The Lissajous curves obtained are shown in FIG. 17A for the system 1 and FIG. 17B for the system 2, respectively. 17 (A) and 17 (B), the change in the curve in the figure is small, and the circle center when this curve is regarded as a part of the circle is substantially coincident with the origin of the xy plane. Thus, it can be seen that the phase difference can be appropriately calculated by the calculation unit by AGC in the adjustment unit.

  Furthermore, the calculation unit obtains the cross-correlation between the phase difference signals for each system, and the waveform of the cross-correlation function acquired as a new phase difference signal for the entire system is plotted with time on the horizontal axis and magnitude of the correlation on the vertical axis. FIG. 18A shows a graph plotted as (amplitude), and FIG. 18B shows an enlarged display in the time axis direction. However, the cross-correlation is obtained for each phase difference signal after removing unnecessary frequency components (0.8 Hz or less) with a high-pass filter in advance.

  Then, in order to evaluate the heartbeat detectability of the phase difference signal obtained for each system of the embodiment, after removing unnecessary frequency components (0.8 Hz or less) with a high-pass filter, the frequency by fast Fourier transform Analysis was performed to obtain a power spectrum for each frequency band, and the result was compared with a power spectrum similarly obtained from the measurement result of the electrocardiograph. Similarly, in order to evaluate the heartbeat detectability of the phase difference signal as a whole system obtained by obtaining the cross-correlation between the phase difference signals, frequency analysis by fast Fourier transform is performed, and the power spectrum for each frequency band. Was compared with the power spectrum similarly obtained from the electrocardiograph measurement results. Each power spectrum of the phase difference signal obtained by the system 1, the phase difference signal obtained by the system 2, and a new phase difference signal by cross-correlation are shown together with those obtained from the electrocardiograph of the comparative example. Each figure is shown in FIG. 19 (A), FIG. 19 (B), and FIG.

  As shown in FIG. 19, the power spectrum of the phase difference signal obtained for each system has a peak that coincides with the power spectrum obtained from the measurement with the electrocardiograph, In a situation where the movement of the subject is small, it can be seen that heartbeat detection is possible even with a single phase difference signal due to the effect of AGC. However, as shown in FIG. 20, the power spectrum of the phase difference signal of the entire system obtained by obtaining the cross-correlation more closely matches that from the electrocardiograph, and the cross-correlation between the phase difference signals is As a result, heart rate can be detected with high accuracy as in the case of measurement by an electrocardiograph, and appropriate heart rate detection can be expected even in a situation where noise further increases, such as when a car is running. In addition, the spectrum shape of the phase difference signal of the entire system is a simple one close to that derived from an electrocardiograph, and even when performing automatic peak detection by a computer, errors are less likely to occur, more reliable detection, Can be evaluated.

  From the above, the power spectrum is also obtained by calculating the final phase difference signal through processing such as signal level adjustment by AGC of the reflected wave signal, addition of two phase difference signals, and cross-correlation calculation between the phase difference signals. Waveforms close to those derived from an electrocardiograph were obtained, indicating the possibility of heartbeat detection, and the above processes were applied to the obtained signals even in non-contact measurement with a subject in a non-stationary environment As a result, it was confirmed that the heart rate could be measured with the same accuracy as that measured by the electrocardiograph.

1, 2, 3 Biological information measurement system 11, 21, 25, 31, 35 Microwave transceiver 11a, 21a, 25a, 31a, 35a Irradiation antenna 11b, 21b, 25b, 31b, 35b First microwave oscillator 11c, 21c, 25c, 31c, 35c Receiving antenna 11d, 21d, 25d, 31d, 35d Directional coupler 11e, 21e, 25e, 31e, 35e Second microwave oscillator 11f, 21f, 25f, 31f, 35f Directional coupler 11g, 21g, 25g, 31g, 35g Reference wave mixer unit 11h, 21h, 25h, 31h, 35h Reflected wave mixer unit 12, 22, 26, 32, 36 Adjustment unit 13, 23, 27, 33, 37 Quadrature detection Units 14, 24, 34 Arithmetic unit 15 Microwave oscillator 16 High frequency oscillator 17 Power Divider 18 Upconverter 50 Subject

Claims (6)

A microwave transmitting / receiving unit that irradiates a non-stationary subject with microwaves, receives a reflected wave on the subject surface of the irradiated wave, and outputs a reflected wave signal and a reference wave signal for quadrature detection;
For the reflected wave signal output from the microwave transmission / reception unit, an adjustment unit that adjusts the signal output level to obtain a reflected wave signal of a predetermined output level;
A quadrature detection unit that performs quadrature detection processing using the reflected wave signal adjusted by the adjustment unit and the reference wave signal, and obtains a signal having an in-phase component and a quadrature component from the reflected wave; and
A biological information measurement system comprising: an arithmetic unit that calculates a phase difference signal between an irradiation wave and a reflected wave from the in-phase component signal and the quadrature component signal output from the quadrature detection unit. The biological information measuring system according to claim 1,
The microwave transceiver unit is
An irradiation antenna for irradiating the subject with microwaves;
A first microwave oscillator for generating a microwave irradiated from the irradiation antenna;
A second microwave oscillator for generating another microwave having a predetermined frequency difference from the microwave;
A reference wave mixer unit for obtaining the reference wave signal having a difference frequency from two microwaves generated by each microwave oscillator;
A receiving antenna for receiving the reflected wave;
A biological information measuring system comprising: a reflected wave mixer unit that obtains the reflected wave signal having a difference frequency from the reflected wave received by the receiving antenna and the microwave from the second micro oscillator . In the living body information measurement system according to claim 1 or 2,
A biological information measuring system comprising offset adjusting means for adjusting a direct current component in the in-phase component signal and the quadrature component signal output from the quadrature detection unit to zero. In the living body information measurement system according to claim 1 or 2,
The calculation unit obtains the phase difference signal from the in-phase component signal and the quadrature component signal after adjusting the DC component in the in-phase component signal and the quadrature component signal output from the quadrature detection unit to zero. A biological information measurement system characterized by The biological information measuring system according to any one of claims 1 to 4,
At least the microwave transmission / reception unit, the adjustment unit, and the quadrature detection unit are arranged in two systems,
The microwave irradiation to the subject in the two microwave transmission / reception units and reception of the reflected wave are respectively performed at locations facing each other across the subject,
A biological information measurement system characterized in that two phase difference signals respectively calculated from the in-phase component signal and quadrature component signal for each system are added, and the added signal is used as a phase difference signal of the entire system. The biological information measuring system according to any one of claims 1 to 4,
At least the microwave transmission / reception unit, the adjustment unit, and the quadrature detection unit are arranged in two systems,
The microwave irradiation and the reception of the reflected wave to the subject in the two microwave transmission / reception units are respectively performed at two different locations,
The cross-correlation between two phase difference signals calculated from the in-phase component signal and the quadrature component signal for each system is obtained, a cross-correlation function signal is obtained, and the cross-correlation function signal is used as the phase difference signal of the entire system. A biological information measuring system characterized by that.