阅读说明：本技术 血压测定装置、车辆装置和血压测定程序 (Blood pressure measurement device, vehicle device, and blood pressure measurement program ) 是由 佐藤敦 本间尚树 小林宏一郎 岩井守生 于 2019-08-27 设计创作，主要内容包括：本发明的目的在于以非接触及非侵害的方式测定生物体的血压。在实验装置(1)中,从发送天线(23)向受检者(7)照射微波,利用接收天线(25)接收其反射波。反射波的相位由于基于脉搏的身体表面的微动而变化,因此能够根据发送波与反射波的相位差来检测脉搏波。而且,实验装置(1)一边连续地检测脉搏波,还一边由穿戴于受检者(7)的血压传感器(5)连续地检测受检者(7)的血压。对受检者(7)的脉搏波进行傅立叶变换而生成脉搏波的频谱,并将其与由血压传感器(5)检测出的受检者(7)的血压进行比较之后,发现了脉搏波的频率成分中的8次谐波与收缩期血压在统计上表示有意义的正相关。根据以上的实验结果,能够采实现使用微波以非接触及非侵害的方式检测对象者的脉搏波,并对其应用上述的相关关系来测定收缩期血压的装置。(The purpose of the present invention is to measure the blood pressure of a living body in a non-contact and non-invasive manner. In the experimental apparatus (1), a microwave is irradiated from a transmission antenna (23) to a subject (7), and a reflected wave thereof is received by a reception antenna (25). Since the phase of the reflected wave changes due to the minute motion of the body surface caused by the pulse, the pulse wave can be detected from the phase difference between the transmitted wave and the reflected wave. The experimental device (1) continuously detects the pulse wave and also continuously detects the blood pressure of the examinee (7) by the blood pressure sensor (5) worn on the examinee (7). A pulse wave of a subject (7) is Fourier-transformed to generate a frequency spectrum of the pulse wave, and the frequency spectrum is compared with the blood pressure of the subject (7) detected by a blood pressure sensor (5), and then a positive correlation statistically significant between the 8 th harmonic in the frequency component of the pulse wave and the systolic blood pressure is found. Based on the above experimental results, it is possible to realize an apparatus for measuring systolic blood pressure by detecting a pulse wave of a subject person in a non-contact and non-invasive manner using microwaves and applying the above correlation to the pulse wave.)

1. A blood pressure measurement device is characterized by comprising:

a pulse wave acquisition unit that acquires a pulse wave from a living body;

a frequency component acquisition unit that acquires a frequency component of the acquired pulse wave; and

and a blood pressure measuring unit that measures the blood pressure of the living body using a frequency component in a frequency band of a predetermined range on a high frequency side based on a fundamental frequency of the pulse wave among the acquired frequency components.

2. The blood pressure measurement device according to claim 1,

the blood pressure measurement means sets a frequency band in which the correlation between the frequency component of the pulse wave and the blood pressure is equal to or greater than a predetermined value as a frequency band in the predetermined range.

3. The blood pressure measurement device according to claim 1 or 2,

the blood pressure measurement unit measures the blood pressure using a component of a harmonic of the fundamental frequency in a frequency band of the predetermined range.

4. The blood pressure measurement device according to claim 1, 2 or 3,

the pulse wave acquisition means acquires the pulse wave from the body surface of the living body in a non-contact manner.

5. The blood pressure measurement device according to claim 4,

the pulse wave acquisition means irradiates the living body with an electromagnetic wave of a predetermined frequency and acquires the pulse wave using a reflected wave of the electromagnetic wave.

6. The blood pressure measurement device according to claim 5,

the blood pressure measurement device is provided with a report means for reporting a change in the measured blood pressure.

7. A vehicle device, characterized in that,

the vehicle device includes the blood pressure measurement device according to claim 6 for measuring the blood pressure of a driver of the vehicle.

8. The vehicular apparatus according to claim 7,

an antenna is provided in a backrest portion of a driver's seat, and the antenna irradiates the electromagnetic wave to the driver and receives a reflected wave of the electromagnetic wave.

9. A blood pressure measurement program that realizes, by a computer, the following functions:

a pulse wave acquisition function for acquiring a pulse wave from a living body;

a frequency component acquisition function for acquiring frequency components of the acquired pulse waves; and

and a blood pressure measurement function for measuring the blood pressure of the living body using a frequency component in a frequency band of a predetermined range on a high frequency side based on the fundamental frequency of the pulse wave among the acquired frequency components.

Technical Field

The present invention relates to a blood pressure measurement device, a vehicle device, and a blood pressure measurement program, and for example, to a device for measuring blood pressure from a pulse wave.

Background

In recent years, health tendency has been increasing with the aging of minority carriers, and blood pressure measurement in daily life has been regarded as important from the viewpoint of prevention of diseases and early detection.

Examples of the blood pressure measurement method include a noninvasive method of directly or indirectly measuring a pulse wave velocity, a pulse wave acceleration, and the like by wearing a dedicated instrument on an arm, a fingertip, or the like and converting the measured values into blood pressure, and an invasive method of directly inserting a balloon or the like into a blood vessel.

In particular, since the noninvasive method gives less load to the human body than the invasive method, research is being actively conducted as described in "guidelines on noninvasive evaluation of vascular function" published by the society of circulatory organs in japan.

Even in noninvasive blood pressure measurement, when a cuff is worn on an arm, a fingertip, or the like, it is necessary to wear a certain device on a subject (measurement subject), which causes a physical and psychological burden on the subject. For example, since pressure is applied by a cuff or the like as needed by the apparatus, the blood pressure fluctuates according to the unpleasant mood, and as a result, some errors may occur in the measurement value. As a psychological phenomenon, there is a well-known white coat effect.

In addition, when monitoring the blood pressure of the driver during driving of the vehicle, it is not practical to wear the devices one by one to the driver.

Therefore, a noncontact blood pressure measurement system is required.

However, since the burden on the subject is small, there is a high demand for noninvasive and non-contact activity measurement, and therefore, although a technique for measuring the number of breaths and the number of pulses of the subject person using microwaves, an optical sensor, and a camera is considered, in a technique for measuring blood pressure in a non-contact manner with respect to a living body, there has been no established methodology as to how to measure blood pressure in a non-contact manner, and a method that can be used in daily life (particularly, that can be used in driving a vehicle) has not been realized due to the difficulty of this technique.

For example, in the technique disclosed in patent document 1, the propagation velocity of a pulse wave is measured by irradiating two parts of a living body with microwaves, and the blood pressure is measured in a non-contact manner based on the description that the propagation velocity of the pulse wave and the blood pressure have a correlation.

In this technique, in a quiet state in which a subject is lying on a bed, for example, microwaves are irradiated while aiming at two predetermined portions of the arm, and there are restrictions on the use in daily life, and it is difficult to use the technique particularly in a vehicle.

Patent document 1: japanese patent laid-open No. 2014-230671.

Disclosure of Invention

The purpose of the present invention is to measure the blood pressure of a living body in a non-contact and non-invasive manner.

(1) In the invention described in claim 1, there is provided a blood pressure measurement device including: a pulse wave acquisition unit that acquires a pulse wave from a living body; a frequency component acquisition unit that acquires a frequency component of the acquired pulse wave; and a blood pressure measurement unit that measures the blood pressure of the living body using a frequency component in a frequency band of a predetermined range on a high frequency side based on a fundamental frequency of the pulse wave among the acquired frequency components.

(2) The invention described in claim 2 provides the blood pressure measurement device described in claim 1, wherein the blood pressure measurement means sets a frequency band in which the correlation between the frequency component of the pulse wave and the blood pressure is equal to or greater than a predetermined value, as the frequency band in the predetermined range.

(3) The invention described in claim 3 provides the blood pressure measurement device according to claim 1 or 2, wherein the blood pressure measurement means measures the blood pressure using a component of a harmonic of the fundamental frequency in the frequency band of the predetermined range.

(4) The invention described in claim 4 provides the blood pressure measurement device according to claim 1, claim 2, or claim 3, wherein the pulse wave acquisition means acquires the pulse wave from a body surface of the living body in a non-contact manner.

(5) The invention described in claim 5 provides the blood pressure measurement device described in claim 4, wherein the pulse wave acquisition means irradiates the living body with an electromagnetic wave of a predetermined frequency, and acquires the pulse wave using a reflected wave of the electromagnetic wave.

(6) The invention described in claim 6 provides the blood pressure measurement device described in claim 5, wherein the blood pressure measurement device includes a notification unit that performs a notification corresponding to a change in the measured blood pressure.

(7) The invention described in claim 7 provides a vehicle device including the blood pressure measurement device described in claim 6 that measures the blood pressure of the driver of the vehicle.

(8) The invention described in claim 8 provides the vehicle device described in claim 7, wherein an antenna is provided in a backrest portion of a driver's seat, the antenna irradiating the driver with the electromagnetic wave and receiving a reflected wave of the electromagnetic wave.

(9) The invention described in claim 9 provides a blood pressure measurement program that realizes, by a computer, the following functions: a pulse wave acquisition function for acquiring a pulse wave from a living body; a frequency component acquisition function for acquiring frequency components of the acquired pulse waves; and a blood pressure measurement function for measuring the blood pressure of the living body using a frequency component in a frequency band of a predetermined range on a high frequency side based on the fundamental frequency of the pulse wave among the acquired frequency components.

According to the present invention, by using the frequency component of the pulse wave, the blood pressure of a living body can be measured in a non-contact and non-invasive manner.

Drawings

Fig. 1 is a diagram for explaining the structure of an experimental apparatus.

Fig. 2 is a diagram showing a mathematical expression.

Fig. 3 is a graph showing a waveform of a pulse wave.

Fig. 4 is a graph showing a spectrum of a pulse wave.

Fig. 5 is a scatter plot depicting the power values at the 8 th harmonic versus systolic blood pressure.

Fig. 6 is a graph showing a correlation coefficient between the reflection power value and the systolic blood pressure.

Fig. 7 is a diagram showing the configuration of the blood pressure measurement device.

Fig. 8 is a flowchart for explaining the procedure of the blood pressure detection process.

Detailed Description

(1) Brief description of the embodiments

The experimental apparatus 1 irradiates the microwave to the examinee (measurement subject) 7 from the transmission antenna 23, and receives the reflected wave thereof by the reception antenna 25. Since the phase of the reflected wave changes due to the minute movement of the body surface caused by the pulse, the pulse wave can be detected from the phase difference between the transmission wave and the reflected wave.

The experimental apparatus 1 continuously detects the blood pressure of the subject 7 from the blood pressure sensor 5 worn on the subject 7 while continuously detecting the pulse wave.

The inventors of the present application have found that, when a frequency component in a frequency band of a predetermined range on the high frequency side of the fundamental frequency among frequency components of the pulse wave generated by performing fourier transform on the pulse wave of the subject 7 to generate a frequency spectrum of the pulse wave and comparing the frequency spectrum with the blood pressure of the subject 7 detected by the blood pressure sensor 5, statistically significant positive correlation is expressed between the frequency component and the systolic blood pressure. In particular, a positive correlation of the 8 th harmonic with systolic blood pressure was found to be statistically significant.

From the above experimental results, it is possible to realize an apparatus for measuring (estimating) systolic blood pressure by detecting a pulse wave of a subject person in a non-contact and non-invasive manner using microwaves and applying the above correlation to the pulse wave. This enables continuous measurement of blood pressure without discomfort or inconvenience.

In the present embodiment, since the blood pressure is measured by frequency analysis of the frequency component of the pulse wave, not the propagation velocity of the pulse wave, it is possible to provide one microwave circuit 2 instead of two.

(2) Detailed description of the embodiments

First, the experimental apparatus will be explained.

Fig. 1 is a diagram illustrating the configuration of an experimental apparatus 1 for examining the correlation between pulse waves and blood pressure.

The experimental apparatus 1 is composed of a microwave circuit 2, a control device 3, a processing device 4, a blood pressure sensor 5, and the like.

The microwave circuit 2 includes a transmitter 21, a transmitter 22, a transmitting antenna 23, a receiver 24, a receiving antenna 25, a mixer 26, a filter 27, and the like.

Although not shown, a chair for seating the subject 7 is provided in the microwave irradiation direction by the microwave circuit 2.

As will be described later, the portions other than the blood pressure sensor 5 in the configuration of the experimental apparatus 1 are incorporated in a blood pressure measurement device 40 that monitors the blood pressure of the driver by a vehicle, and are used to measure (estimate) the blood pressure of a measurement subject (for example, the driver, a patient in a hospital, or the like).

The transmitter 21 includes a device for microwave oscillation, generates a microwave of a predetermined frequency from a continuous wave, outputs the microwave to the transmitter 22, and outputs a part of the microwave as a reference wave to the mixer 26.

In the present embodiment, as an example of an electromagnetic wave for detecting a pulse wave, a microwave of 5[ GHz ] generated by the transmitter 21 is used.

The transmitter 22 transmits the microwave generated by the transmitter 21 to the space from the transmission antenna 23.

The transmission antenna 23 uses a 16-element block array antenna, and there are 16 sets of the transmitter 22 and the transmission antenna 23, but 1 set is illustrated in fig. 1.

In the receiver 24, a reflected wave returned by reflection of the irradiation wave (transmission wave) from the transmitter 22 by the target (subject 7) is received by the receiving antenna 25 and sent to the mixer 26.

The reception antenna 25 uses a 4-element block array antenna, and there are four sets of the reception antenna 25 and the receiver 24, but 2 sets are illustrated in fig. 1.

In this way, the experimental apparatus 1 is a MIMO (Multiple Input Multiple Output) system in which 16 elements are transmitted and 4 elements are received. In addition, the element spacing was 0.5 wavelength.

With such a configuration, it is possible to make the directivity of the microwave sharp, and also to finely adjust the direction of the microwave, and irradiate the microwave to a portion where the pulse wave can be detected favorably (the heart portion of the subject 7 according to the experiment of the inventor).

The mixer 26 mixes the reflected wave received by the receiver 24 with the reference wave from the transmitter 21 to generate a beat frequency (beat) and a mixed wave, and outputs the beat frequency and the mixed wave to the filter 27.

The filter 27 is a filter that passes only a frequency band necessary for measurement of a pulse wave among beat waves output from the mixer 26.

The body surface of the subject 7 vibrates finely due to the cardiopulmonary activity, and fine variations in the reflection surface (body surface) due to this generate phase changes of the reflected waves (microwave doppler).

When the radiation wave of a fixed frequency is mixed with the reflected wave as a reference wave, a beat frequency based on the phase difference is generated, and the pulse wave can be detected and reproduced by using the beat frequency.

In this way, the experimental device 1 is able to measure vibrations of the body surface in a non-contact and non-invasive manner.

In addition, even if the subject 7 wears clothes such as cotton, chemical fibers, and the like, the subject 7 can keep wearing clothes because microwaves penetrate them. In this way, the method using the microwaves can be used in a non-contact and clothing environment, and is therefore suitable for measuring blood pressure in daily life such as when driving a vehicle.

In this way, the experimental apparatus 1 includes a pulse wave acquisition unit that irradiates a living body (subject 7) with electromagnetic waves of a predetermined frequency, acquires pulse waves from the living body using reflected waves of the electromagnetic waves, and can acquire pulse waves from the body surface of the living body in a non-contact manner.

The blood pressure sensor 5 is configured using a cuff worn on the right index finger of the subject 7, and thus can observe a temporal change in blood pressure with the sphygmomanometer according to a change in a pressure value based on a blood flow.

In the experimental apparatus 1, a continuous blood pressure meter (biomedical MIDI (biological Instrument Digital Interface)) is used to measure the actual blood pressure value of the subject 7 at the same time as the detection of the pulse wave by the microwave circuit 2.

The control device 3 is a control device that controls driving of the transmitter 21.

The processing device 4 is constituted by the following components and the like: an oscilloscope which displays a pulse wave based on a signal output from the microwave circuit 2; a spectrum analyzer which transforms a pulse wave into a spectrum by a Fourier transform based on FFT (Fast Fourier transform); a sphygmomanometer that measures the blood pressure of a subject 7 by a blood pressure sensor 5; and a computer that analyzes the information derived from them.

As described above, the experimental apparatus 1 can continuously obtain the pulse wave of the subject 7 by the microwave in a non-contact manner, and can continuously detect the blood pressure of the subject 7 by the blood pressure sensor 5 in parallel with the pulse wave.

In this experiment, the pulse wave detected by the microwave and the blood pressure detected by the blood pressure sensor 5 were compared to examine the correlation between the pulse wave and the systolic blood pressure (sbp).

Next, a method of evaluating the characteristics of the pulse wave and the systolic blood pressure will be described.

In general, when there are n transmission elements and m reception elements, the variable MIMO channel matrix h (t) is represented by a matrix of m rows and n columns as in expression (1) in fig. 2.

In this experiment, the propagation path having the highest time-average power among the combinations of the receiving element (transmitting antenna 23) and the transmitting element (receiving antenna 25) was selected and the experiment was performed.

When the combination of the receiving element and the transmitting element at this time is m and n, respectively, the propagation channel coefficient of the propagation path is represented as h "mn" (t).

Note that, though mn is represented by an index of h in equation (1) in fig. 2, the subscript is partially enclosed by "mn" in the present specification. The same is described below.

In this experiment, the correspondence between the power value of each frequency component of the pulse wave (power value of the frequency component due to the biological information) and the actual systolic blood pressure value in a certain time interval Δ t was observed.

In this way, the experimental apparatus 1 includes a frequency component acquisition unit that acquires the frequency component of the pulse wave using the power value. The power value may be an absolute value or a relative value with respect to some reference.

The frequency response obtained by fourier transforming the kth propagation channel divided by an arbitrary time interval Δ t is denoted as f mn (ω, t k). Here, ω denotes an angular frequency, and tk denotes a time of the kth section.

N is the number of harmonics based on the fundamental frequency of the heart rate of the subject 7, the lower limit of the frequency component corresponding to each number is ω "L" (n), and the upper limit is ω "H" (n).

For example, since the subject 7 beats its heart about 60 times in one minute, the fundamental frequency is about 1[ Hz ] (generally, about 0.7 to 1.5[ Hz ]), and the frequencies of 2 times, 3 times, · · are about 2[ Hz ], 3[ Hz ], · · right.

The power P "n" (t "k") of the nth harmonic component is represented by equation (2) in FIG. 2.

In the present embodiment, the power pn (tk) of the fundamental wave component and the harmonic component of the waveform of the pulse wave of the subject 7 is obtained by fourier transform using FFT, and the average value of the actual systolic blood pressure corresponding to the time interval where pn (tk) is obtained by the blood pressure sensor 5, and the correlation characteristics between both are evaluated.

Next, the experiment will be described.

In this experiment, the possibility of non-contact blood pressure measurement using microwaves was investigated by comparing the reflection response of microwaves irradiated to a living body with the actual systolic blood pressure and evaluating the correlation characteristics.

In this experiment, the channel measurement time was 210 seconds, and the sampling frequency (acquisition rate of the MIMO channel) was 200[ Hz ].

In consideration of the frequency resolution, the time interval Δ t for fourier analysis is 1024 samples, the time is 5.12 seconds, and the hamming window is used for fourier transform.

This experiment was performed in cooperation with 7 healthy men aged 20 years, and the actual continuous blood pressure value of the subject 7 was measured simultaneously using the blood pressure sensor 5.

In order to reduce the influence of body movement of the subject 7, the subject 7 is seated at a distance of 30cm in the antenna frontal direction and is in a resting state.

In this experiment, in order to maintain the subject 7 in a resting state and promote an arbitrary blood pressure change, the subject 7 was put on goggles for VR (Virtual Reality) to confirm a change in reflected waves based on the blood pressure value, and video stimulation was applied after 60 seconds passed after the start of measurement.

Next, the experimental results will be explained.

Fig. 3 is a graph showing the waveform of the pulse wave of the subject 7 detected from the microwave.

The vertical axis represents the absolute value of the detected voltage, and the horizontal axis represents time in seconds. The pulse wave 31, · based on the pulse occurs about 1 time per 1 second as shown in the figure.

As shown in the figure, even in the pulse wave 31, fine features of the waveform are detected well, and it is expected that the features of the pulse wave 31 are extracted based on frequency analysis.

Fig. 4 is a graph showing a spectrum of a pulse wave.

The waveform is obtained by converting the pulse wave 31 into a frequency region by fourier transform, and indicates the level (power) of each frequency component constituting the pulse wave.

The vertical axis represents the level of the frequency component by power (voltage value), and the horizontal axis represents frequency.

As is clear from the graph, the basic wave including the pulse wave at most, that is, the component 33 of about 1 Hz caused by the beating of the heart is included.

Fig. 5 is a scatter diagram depicting the correspondence of the power value of the 8 th harmonic of the reflected wave (horizontal axis) and the systolic blood pressure (SBP: vertical axis) for all subjects.

The power value of the 8 th harmonic is obtained by fourier transforming the pulse wave 31, and the systolic blood pressure is measured by using the blood pressure sensor 5.

In the present experiment, the same scatter diagram was created from the fundamental wave to the 20 th harmonic wave to obtain the correlation coefficient, and the correlation coefficient of the 8 th harmonic wave was the highest, so the 8 th harmonic wave scatter diagram is cited here.

A straight line 35 in fig. 5 represents a regression line obtained by the least square method.

As shown in fig. 5, when the regression line is y 313.1464+2.714x, the correlation coefficient r is 0.50932, the sampling number n is 804, and the P value is less than 0.05 with respect to the confidence interval of 95%, a significant positive correlation tendency is observed.

Furthermore, pearson's product-rate correlation was used in this study to calculate the correlation coefficient, and P values less than 0.05 were considered statistically significant.

Incidentally, when the same analysis is performed for the fundamental wave, y is 148.7285+0.61697x, the correlation coefficient r is 0.32265, and the P value is less than 0.05 with respect to the confidence interval 95%, a significant positive correlation tendency is observed.

Fig. 6 is a graph showing a correlation coefficient between the reflection power value and the systolic blood pressure for each harmonic from the fundamental wave to the 20 th harmonic.

From this graph, the correlation coefficient between the 8 th harmonic component based on the received power of the pulse wave and the systolic blood pressure is the highest, and this value is 0.50932 as described above.

Therefore, when measuring the systolic blood pressure from the pulse wave, it is preferable to use the 8 th harmonic component of the pulse wave, and it is considered that the systolic blood pressure can be measured from the level of the component using the above-described correlation.

In the present experiment, the correlation coefficient was measured for each frequency of the harmonic wave, and it was found that the correlation at the frequency of the 8 th harmonic wave was the highest, and when the correspondence between the correlation coefficient and the frequency was examined in more detail, the position slightly shifted from the frequency of the 8 th harmonic wave was the highest in some cases.

However, from the shape of the graph, it is considered that the most preferable frequency component exists in the vicinity of the frequency of the 8 th harmonic in the blood pressure measurement. In addition, even in the vicinity of the 12 th harmonic, a peak is not observed unlike the 8 th harmonic.

In the present experiment, the microwave of 5[ GHz ] was used, but when the microwave of other frequencies was used, the relationship number was also considered to be high at the frequencies of harmonics of other orders.

Therefore, it is considered that a preferred frequency band in blood pressure measurement is a frequency band in which the correlation coefficient between the n-1 th harmonic and the n +1 th harmonic around the n-th harmonic is equal to or greater than a predetermined value, and more preferably, is a frequency near the n-th harmonic or at the n-th harmonic in the frequency band.

When the frequency of the microwave is 5[ GHz ], the correlation coefficient becomes higher in the vicinity of the 8 th harmonic, that is, when n is 8, and a frequency band in which the correlation coefficient is 0.3 or more, or the correlation coefficient is 0.4 or more, preferably 0.5 or more between the frequency of the 7 th harmonic and the frequency of the 9 th harmonic is a frequency band suitable for blood pressure measurement.

The blood pressure measurement device 40 described later measures the systolic blood pressure of the subject by comparing the level of the 8 th harmonic in the frequency included in the frequency band with the correlation shown in fig. 5.

As described above, the blood pressure measurement device 40 includes the blood pressure measurement unit that measures the blood pressure of the living body using the frequency component in the frequency band of the predetermined range on the high frequency side based on the fundamental frequency of the pulse wave among the frequency components, and the blood pressure measurement unit uses the frequency band in which the correlation between the frequency component of the pulse wave and the blood pressure is equal to or more than the predetermined value as the frequency band of the predetermined range used for the blood pressure measurement.

The blood pressure measuring means measures the blood pressure using the harmonic component of the fundamental frequency in the frequency band of the predetermined range (in the example of the blood pressure measuring device 40, the 8 th harmonic component in the frequency band).

In summary, in this experiment, a living body is irradiated with microwaves, and correlation characteristics are evaluated based on the correspondence between the microwave doppler response and the actual blood pressure (particularly, systolic blood pressure). From the experimental results, it was found that there was a positive correlation between the power value of the reflected wave and the systolic blood pressure value. When the heart rate of the subject 7 is set to the fundamental frequency, a higher positive correlation is observed in the harmonic components thereof.

Fig. 7 is a diagram showing the configuration of the blood pressure measurement device 40 produced using the above-described experimental results.

As the blood pressure measurement device 40 of fig. 7, for example, a case will be described in which a dedicated IC chip or the like is used to realize downsizing and is mounted on a vehicle, and the blood pressure of a driver is measured and monitored.

The blood pressure measurement device 40 can also be used to measure blood pressure on a daily basis at home or to measure blood pressure of a patient in a medical facility.

In this way, the vehicle device of the vehicle includes the blood pressure measurement device 40 that measures the blood pressure of the driver of the vehicle.

The blood pressure measurement device 40 is configured using a CPU (Central Processing Unit) 41, a ROM (Read Only Memory) 42, a RAM (Random Access Memory) 43, an interface 44, an input device 45, an output device 46, a storage device 47, a control device 3, a Processing device 4, and a microwave circuit 2 (not shown).

The CPU41 controls various parts of the blood pressure measurement device 40 or performs various arithmetic processes based on programs stored in the ROM42 and the storage device 47.

In the present embodiment, the following processing is performed to measure the blood pressure of the subject person (driver) by acquiring the pulse wave of the subject person for blood pressure measurement (driver) in cooperation with the control device 3 and the processing device 4.

The ROM42 is a read-only memory in which basic programs, parameters, and the like for operating the blood pressure measurement device 40 are stored.

The RAM43 is a readable and writable memory, and temporarily stores blood pressure measurement programs, data, and the like stored in the storage device 47, and provides a work memory for the CPU41 to perform various kinds of information processing.

The interface 44 is an interface for connecting the control device 3 and the processing device 4 to the CPU 41. The CPU41 controls the control device 3 via the interface 44 to operate the microwave circuit 2 or receive the level of the 8 th harmonic from the processing device 4.

The input device 45 includes an input device such as a touch panel, a keyboard, and a mouse, and receives an operation by the user from the blood pressure measurement device 40.

The output device 46 includes an output device such as a display, a speaker, and a printer, for example, and displays an operation screen of the blood pressure measurement device 40 on the display, or reports a measurement value of the blood pressure and an alarm based on a change in the blood pressure to the subject using the display, the speaker, and the printer.

Even if the pulse of the driver is normal, the blood pressure may be lowered and attention may be required. In such a case, the blood pressure measurement device 40 quickly detects a change in blood pressure, and changes the content of a report, such as a notification of blood pressure, a rest advice, an emergency report, etc., in stages according to the importance of the change. Specifically, when it is determined that the blood pressure is continuously decreased, not decreased by the fluctuation, it is determined that shock symptoms may be caused, and the blood pressure decrease is reported based on the magnitude, the decrease rate, and the like.

In addition, when the blood pressure becomes high beyond a predetermined value, it is considered to be tense, and therefore, it is possible to make a rest suggestion in the same manner.

In this way, the blood pressure measurement device 40 includes a notification unit that performs a notification corresponding to a change in the measured blood pressure.

The storage device 47 includes a large-capacity medium such as a semiconductor storage device or a hard disk, and stores a blood pressure measurement program that causes the CPU41 to obtain the level of the 8 th harmonic from the processing device 4 and to calculate a blood pressure value from the correlation between the level blood pressure of the 8 th harmonic, other programs, data of past measurement values, and the like.

The control device 3 controls the driving of the microwave circuit 2, not shown, based on a signal from the CPU 41.

The processing device 4 has a function of detecting a pulse wave from a reflected wave of the microwave, and performs fourier transform on the detected pulse wave to output a level of 8 th harmonic to the CPU 41.

Both the control device 3 and the processing device 4 are IC chips limited to necessary functions and are miniaturized to such an extent that they can be mounted on a vehicle.

The transmitting antenna 23 and the receiving antenna 25 constituting the microwave circuit 2, not shown, are embedded in the backrest portion of the driver's seat, and the transmitting antenna 23 irradiates the back portion near the heart of the driver with microwaves, and the receiving antenna 25 receives reflected waves modulated in accordance with the pulse waves. The transmitting antenna 23 and the receiving antenna 25 may be disposed on the instrument panel, the steering wheel, the upper portion of the windshield glass, or the like, so that the vicinity of the heart is irradiated from the front of the driver.

Thus, the blood pressure measurement device 40 can detect the pulse wave of the driver without touching and wearing clothes.

In this way, the blood pressure measurement device 40 includes an antenna that irradiates the electromagnetic wave to the driver and receives the reflected wave thereof, in the backrest portion of the driver's seat.

Fig. 8 is a flowchart for explaining the procedure of the blood pressure detection process for detecting the systolic blood pressure by the blood pressure measurement device 40.

The following processing is performed by the CPU41 in cooperation with the control device 3 and the processing device 4 according to the blood pressure measurement program.

First, the CPU41 drives the control device 3 to irradiate a target person (a driver of a vehicle, a user at home, a patient in a hospital, etc.) with microwaves from the microwave circuit 2 (step 5).

On the other hand, the processing device 4 detects a pulse wave from the reflected wave reflected from the subject (step 10), and further performs frequency analysis on the pulse wave (step 15).

Further, the processing device 4 detects the level value of the 8 th harmonic and transmits it to the CPU41 (step 20).

In contrast, the CPU41 receives a level value from the processing device 4 and stores it in the RAM 43.

Next, the CPU41 substitutes the level value into a predetermined calculation formula using the correlation between the level value of the 8 th harmonic stored in the RAM43 and the systolic blood pressure, performs calculation, and stores the measurement value of the systolic blood pressure calculated by the calculation in the RAM43 as a measurement value (step 25).

Then, the CPU41 outputs the blood pressure stored in the RAM43 to the output device 46 (step 30).

In this way, the blood pressure measurement device 40 can measure the systolic blood pressure of the subject person without contact and without invasion, while wearing clothes, and can detect vital signs by using a unique algorithm.

As described above, the blood pressure measurement device 40 can detect a pulse wave from a reflection response of a microwave irradiated to a living body, perform frequency component decomposition of the pulse wave, and measure systolic blood pressure using high-order component power of a fundamental frequency (about 0.7 to 1.5 Hz) of the pulse wave.

This makes it possible to easily measure daily activity without contact and without causing damage, and is effective as a means for finding a sign of a disease in addition to grasping health conditions.

While the present embodiment has been described with reference to an example, various embodiments and modifications are possible.

For example, although the blood pressure measurement device 40 uses MIMO, it may use SIMO (Single Input Multiple Output) using a plurality of reception antennas 25 for one transmission antenna 23, or SISO (Single Input Single Output) using a pair of the transmission antenna 23 and the reception antenna 25.

Since the blood pressure measurement device 40 can measure the systolic blood pressure from the waveform of the pulse wave, the above algorithm (detecting the level of the 8 th harmonic and measuring the systolic blood pressure using the above correlation) can be used in both the contact type and the invasive type as long as the measurement device obtains the pulse wave.

In the present embodiment, microwaves are used as the electromagnetic waves, and electromagnetic waves of other frequency bands such as laser light and visible light can be used.

In the present embodiment, the pulse wave is detected from the reflection response of the microwave irradiated to the living body, and the frequency component decomposition of the pulse wave is performed, but the systolic blood pressure can be measured in consideration of personal characteristic values (age, etc.) in addition to the high-order component power of the fundamental frequency of the pulse wave.

Description of reference numerals

1 … experimental set-up; 2 … microwave circuit; 3 … control device; 4 … processing means; 5 … blood pressure sensor; 7 … subject; 21 … emitter (Osc); 22 … transmitter (Tx); 23 … a transmit antenna; 24 … receiver (Rx); 25 … a receiving antenna; 26 … mixer (Mix); 27 … Filter (Filter); 31 … pulse wave; 33 … component; 40 … blood pressure measuring device; 41 … CPU; 42 … ROM; 43 … RAM; a 44 … interface; 45 … input devices; 46 … output device; 47 … storage device.