JP2021016431A - Pulse wave measuring apparatus and measuring method, and blood pressure measurement device - Google Patents

Abstract

To improve measurement precision of a pulse wave by reducing effect of a reflected wave by the region unrelated to the region to be measured.SOLUTION: One aspect of this invention generates a transmitted wave comprising a short pulse-shaped burst wave in a transmission unit 1 and transmits it toward an artery 4 of a region to be measured in order to measure a pulse wave. Then, the pulse width of the burst wave is set so that a range of separable and identifiable distance may comprise the artery 4 being the region to be measured by the distance resolution to start from the transmission unit 1, and may not comprise an object positioned in the distant place from the artery 4. Then, the one aspect of this invention receives the reflected wave by the artery 4 of the transmitted wave with a receiving unit 2, detects this receiving waveform signal by using the burst wave as a reference signal, and detects the pulse wave signal PS for representing the pulsation of the artery 4 by inputting the received signal after this detection into a pulse wave detection unit 3.SELECTED DRAWING: Figure 1

Description

An embodiment of the present invention relates to, for example, a pulse wave measuring device and a pulse wave measuring method for measuring a pulse wave using radio waves, and a blood pressure measuring device for estimating blood pressure based on the pulse wave.

As a device for measuring a pulse wave of a living body using radio waves, for example, the device disclosed in Patent Document 1 is known. This device includes a transmitting antenna and a receiving antenna arranged so as to face a measured portion such as a blood vessel or a body surface, and transmits radio waves (measurement signals) from the transmitting antenna toward the measured portion (target object). The pulse wave signal is obtained by receiving the reflected wave (reflected signal) of the transmitted radio wave by the measured portion by the receiving antenna.

Japanese Patent No. 5879407

However, since the radio wave transmitted from the antenna has a spread, it is also radiated to a biological part other than the part to be measured by the user and other users and structures located in the vicinity. Therefore, the receiving antenna receives not only the reflected wave by the part to be measured by the user but also the radio wave reflected by other living parts and peripheral objects unrelated to the measurement of the pulse wave. As a result, the reflected wave from the user's other biological part or peripheral object becomes noise and affects the reflected wave of the part to be measured, which lowers the measurement accuracy of the pulse wave.

The present invention has been made by paying attention to the above circumstances, and an object of the present invention is to provide a technique for improving the measurement accuracy of pulse waves by reducing the influence of reflected waves by a portion unrelated to the portion to be measured. ..

In order to solve the above problems, the first aspect of the pulse wave measuring device or method according to the present invention is to transmit a transmitted wave composed of radio waves toward a measured portion of a living body having a transmitting circuit and a transmitting antenna. A receiving unit having a unit, a receiving circuit and a receiving antenna, and receiving a reflected wave of the transmitted wave by the measured portion, and a pulse representing the pulsation of the measured portion based on a signal output from the receiving unit. It is provided with a pulse wave detection unit that detects a wave signal. Then, by the transmission circuit, one of the range of the distance that can be separated and identified by the distance resolution starting from the transmission antenna includes the measured portion and does not include an object located at least far from the measured portion. A short pulse-shaped burst wave having a set pulse width is generated, the burst wave is output to the transmitting antenna as the transmitting wave, and a reference wave generated at the same time as the transmitting wave is output to the receiving circuit. The receiving circuit outputs a signal representing the phase difference between the reflected wave and the reference wave received by the receiving antenna to the pulse wave detection unit.

According to the first aspect, as the transmitted wave transmitted from the transmitting unit, one of the range of the distance that can be separated and identified by the distance resolution starting from the transmitting antenna includes the measured portion and at least one of the measured portions. A short pulse burst wave whose pulse width is set so as not to include a distant object is used. Therefore, for example, even if reflected waves from a noise source such as another user or a structure existing in or around another biological part located far from the measured part are received, these reflected wave components are excluded from the detection target. It is prevented from being mixed into the pulse wave signal. Therefore, it is possible to improve the detection accuracy of the pulse wave signal.

Further, in the receiving circuit, the phase of the reflected wave is detected by using the burst wave generated by the transmitting circuit at the same timing as the transmitting wave and transmitted at a fixed distance in the device as the reference wave, so that the part to be measured It is possible to detect the phase change of the reflected wave due to the pulsation of the wave with a relatively simple circuit such as a detection circuit.

In the second aspect of the pulse wave measuring device according to the present invention, when the transmission circuit uses the radial artery of the user's wrist as the measurement site, the range of the distance that can be separated and identified by the distance resolution is the transmission unit. The pulse width is set so as to be within the range not including the body of the user.

According to the second aspect, for example, when the measurement site is the radial artery of the user's wrist, the reflected wave component by the body portion of the user is excluded from the detection target, and the contamination into the pulse wave signal is prevented. To. Therefore, it is possible to eliminate the influence of the user's body and obtain a high-quality pulse wave signal.

In the third aspect of the pulse wave measuring device according to the present invention, when the transmission circuit uses the radial artery of the user's wrist as the measurement site, the range of the distance that can be separated and identified by the distance resolution is the transmission. The pulse width is set so as to be within a range that does not include an object located around the user from the unit.

According to the third aspect, for example, when the measurement site is the radial artery of the wrist of the user, another user, a structure such as a pillar or a wall, an office device, or the like exists around the user. However, the reflected wave components due to these are excluded from the detection target, and the mixing into the pulse wave signal is prevented. Therefore, it is possible to obtain a high-quality pulse wave signal by eliminating the influence of other users and objects existing around the user.

A fourth aspect of the pulse wave measuring device according to the present invention is to set the pulse width corresponding to a range of distances that can be separated and identified by the distance resolution when the distance resolution is Δd and the light speed is c. , The frequency bandwidth Δf of the burst wave is set to a value satisfying the relationship of Δd = c / 2 / Δf.
According to this fourth aspect, it is possible to obtain a desired distance resolution by managing the frequency bandwidth Δf of the burst wave.

One aspect of the blood pressure measuring device according to the present invention is provided with at least one set of pulse wave measuring devices, and the at least one set of pulse wave measuring devices is attached to a living body so as to be arranged facing an artery as a measurement site. Further, a blood pressure estimation unit connected to the at least one set of pulse wave measuring devices is provided, and the blood pressure estimation unit is used in the measured portion detected by each pulse wave detecting unit of the at least one set of pulse wave measuring devices. The calculation is performed based on a calculation unit that calculates a feature amount of the waveform of the pulse wave signal based on the corresponding pulse wave signal and information representing the relationship between the feature amount and the blood pressure value stored in the memory in advance. It is configured to include an estimation unit that estimates the blood pressure value corresponding to the feature amount and an output unit that outputs the estimated blood pressure value.

According to one aspect of the blood pressure measuring device according to the present invention, the measured portion has a range of distances that can be separated and identified by the distance resolution starting from the transmitting antenna as the transmitted wave by at least one set of pulse wave measuring devices. A short pulse burst wave whose pulse width is set so as to include and not include an object located at least far from the measurement site is used. Therefore, for example, even if reflected waves from a noise source such as another user or a structure existing in or around another biological part located far from the measured part are received, these reflected wave components are excluded from the detection target. It is prevented from being mixed into the pulse wave signal. Therefore, it is possible to obtain a pulse wave signal with higher detection accuracy. Then, by calculating the feature amount of the waveform based on this pulse wave signal and estimating the blood pressure based on this feature amount, it is possible to estimate the blood pressure with high accuracy.

Further, as another aspect of the blood pressure measuring device according to the present invention, two sets of the pulse wave measuring devices are provided, and these two sets of pulse wave measuring devices are used as the first site of the artery as the measured site and the first portion. It is attached to the living body so as to be arranged opposite to the second site on the downstream side of the first site, and each pulse wave detection of the two sets of pulse wave measuring devices is performed by the blood pressure estimation unit as a feature amount of the waveform. Based on the first pulse wave signal corresponding to the first part and the second pulse wave signal corresponding to the second part detected by the part, the first part and the second part The pulse wave velocity may be calculated, and the blood pressure value corresponding to the calculated pulse wave velocity may be estimated.
With such a configuration, it is possible to estimate the blood pressure based on the pulse wave velocity (PTT) of the artery.

That is, according to each aspect of the present invention, it is possible to provide a technique for reducing the influence of the reflected wave by a portion unrelated to the portion to be measured and improving the measurement accuracy of the pulse wave.

FIG. 1 is a block diagram showing an application example of one of the pulse wave measuring devices according to the present invention. FIG. 2 is a diagram used for explaining the operation of the application example shown in FIG. FIG. 3 is a perspective view showing the appearance of the blood pressure measuring device according to the embodiment of the present invention. FIG. 4 is a plan view showing the arrangement positions of the antenna substrate and the pressing cuff with respect to the wrist when the blood pressure measuring device shown in FIG. 3 is attached to the left wrist of the user. FIG. 5 is a block diagram showing a circuit configuration of the blood pressure measuring device shown in FIG. FIG. 6 is a waveform diagram for explaining the detection operation of the reflected wave by the artery as the measurement site. FIG. 7 is a waveform diagram for explaining an operation of eliminating noise waves by an object existing far from the measured portion.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings.

[Application example]
First, one application example of the pulse wave measuring device according to the present invention will be described.
FIG. 1 is a block diagram showing an application example of one of the pulse wave measuring devices according to the present invention. In this example, the pulse wave measuring device includes a transmitting unit 1, a receiving unit 2, and a pulse wave detecting unit 3. The transmitting unit 1 and the receiving unit 2 are arranged to face each other at a position close to the artery 4 as a measurement site.

The transmission unit 1 has a transmission circuit and a transmission antenna, generates, for example, a short pulse burst wave TS by the transmission circuit, and transmits the transmission wave E composed of the burst wave as a radio wave from the transmission antenna to the artery 4. To do. The short pulse burst wave TS has a pulse width PW within a range in which the distance resolution starting from the transmitting unit 1 does not include the artery 4 and does not include an object located at least farther from the artery 4. Is set to. At this time, as the object located far away, for example, when the measurement site is the radial artery of the wrist of the user, the torso of the user or another user or structure existing around the user is assumed.

The receiving unit 2 has a receiving circuit and a receiving antenna, and receives the reflected wave E'from the surface of the artery 4 of the transmitted wave E transmitted from the transmitting unit 1 by the receiving antenna. At this time, the reference wave FS generated from the transmission circuit at the same timing as the burst wave TS as the transmission wave is input to the reception circuit, and the reception circuit detects the reflected wave E'by the reference wave FS. Then, the signal RS'representing the phase difference between the reflected wave E'and the reference wave FS and the reception intensity of the reflected wave E'is output.

The pulse wave detection unit 3 generates and outputs a pulse wave signal PS representing the pulsation of the artery 4 based on the reception signal RS'output from the reception unit 2.

The pulse wave measuring device configured as described above operates as follows.
FIG. 2 is a waveform diagram illustrating the operation. That is, in the transmission unit 1, a short pulse burst wave TS is generated by the transmission circuit, and the transmission wave composed of the burst wave TS becomes a radio wave E from the transmission antenna and is transmitted to the artery 4 as the measurement site. The transmitted radio wave E is reflected by the blood vessel surface of the artery 4, and the reflected wave E'is received by the receiving antenna of the receiving unit 2. At this time, the reference wave FS is supplied from the transmission unit 1 to the reception circuit of the reception unit 2. The receiving circuit detects the received waveform signal RS of the reflected wave E'received by the receiving antenna by the reference wave FS.

By the way, the reference wave FS is, for example, a burst wave generated at the same timing as the burst wave TS as a transmission wave, and has the same frequency component, generation timing, and pulse width RW as the transmission wave. Moreover, the pulse width RW is such that the range of the distance that can be separated and identified by the distance resolution starting from the transmission unit 1 is within the range that includes the artery 4 and does not include an object located at least farther from the artery 4. It is set. Therefore, when the received waveform signal RS _S of the reflected wave E 'of arterial 4 detected by the reference wave FS, arterial 4 of the measurement site in the range of separation discernible distance by distance resolution with this pulse wave measuring device Therefore, the receiving signal RS'after detection is output from the receiving unit 2, for example, as shown in FIG. The detection signal RS'represents the phase difference between the reflected wave E'and the reference wave FS and the reception intensity of the reflected wave E'.

Therefore, when this detection signal is input to the pulse wave detection unit 3, the pulse wave detection unit 3 obtains a signal representing the pulsation of the artery 4 at a certain time point by, for example, converting the phase difference of the detection signal into an amplitude. Be done. That is, by transmitting a transmitted wave at a period sufficiently shorter than the pulsation period of the artery 4, detecting the phase of the reflected wave and converting each into an amplitude, the pulse wave detection unit 3 has a pulse representing the pulsation waveform of the artery 4. It becomes possible to obtain the wave signal PS.

On the other hand, the reflected wave E'is reflected by a body portion such as the user's chest located farther than the artery 4, and also by an object that is a noise source such as another user's body or an indoor structure existing around the user. Waves may be included. However, the noise source object located farther than the artery 4 is out of the range of the distance that can be separated and identified by the distance resolution of the pulse wave measuring device. Therefore, the reflected wave by the object of the noise source the received waveform signal RS _N of (noise wave), even if an attempt is detected by the reference wave FS at the receiving unit 2, not detected.

As described above, according to one application example of the pulse wave measuring device according to the present invention, the range of the distance that can be separated and identified by the distance resolution starting from the transmitting unit 1 includes the artery 4 and this artery. A short pulse burst wave TS in which the pulse width is set so as to be within a range not including an object located at least farther than 4 is used. Therefore, even if the reflected wave by the noise source located farther than the arterial 4 is received in addition to the reflected wave E'by the artery 4 as the measurement site, the received waveform signal RS of the reflected wave by these noise sources is received. _N is not detected. Therefore, it is possible to obtain a high-quality pulse wave signal PS by increasing the S / N of the pulse wave signal.

[One Embodiment]
(Configuration example)
(1) Structure of the device FIG. 3 is a perspective view showing the overall structure of the blood pressure measuring device having the function of the pulse wave measuring device according to the embodiment of the present invention.

The blood pressure measuring device is of a type used by being worn on the left wrist of the subject, and is worn on the left wrist of the user so as to surround the outer circumference thereof, and the band 20 having a buckle 24 and the band 20. It includes a main body 10 that is integrally attached.

A transmission / reception unit 40 constituting the first and second pulse wave sensors is provided at a position on the outer peripheral surface of the band 20 opposite to the main body 10. Further, in the band 20, a pair (transmission / reception antenna group) of the transmission / reception antennas TX1, RX1 and TX2, RX2 is arranged on the inner peripheral surface 20a of the portion where the transmission / reception unit 40 is arranged. The position of the pair of these transmission / reception antennas TX1, RX1 and TX2, RX2 is set so as to face the radial artery passing through the left wrist when the user as the subject passes the left hand through the band 20. Has been done.

A display device 50 forming a display screen is provided on the top surface (the surface on the side farthest from the measurement portion) 10a of the main body 10. Further, an operation unit 52 for inputting an instruction from the user is provided at a position along the side surface of the main body 10 (the side surface on the left front side in FIG. 3) on the outer peripheral surface 20b of the band 20.

In this example, the operation unit 52 includes a push-type switch, and inputs an operation signal according to a user's instruction to start or stop blood pressure measurement to the processing unit in the main body 10. The operation unit 52 is not limited to the push type switch, and may be, for example, a pressure sensitive type (resistive type) or a proximity type (capacitance type) touch panel type switch. Further, a microphone (not shown) may be provided to input a blood pressure measurement start instruction by a user's voice. Further, the operation unit 52 is not essential, and the processing unit described later can be configured to automatically generate a blood pressure measurement start instruction or a stop instruction in response to, for example, an activation signal output from a timer. ..

When the blood pressure measuring device is attached to the left wrist, the user who is the subject is measured in the direction indicated by the arrow A in FIG. 3 with the buckle 24 opened in the direction of arrow B and the diameter of the ring of the band 20 is increased. Passes his left hand through band 20. Then, the user adjusts the position of the band 20 in the circumferential direction of the left wrist, and the transmission / reception antennas TX1, RX1 and TX2, RX2 installed on the inner peripheral surface of the band 20 on the radial artery passing through the left wrist. Set so that the pairs of are facing each other. As a result, the pair of transmission / reception antennas TX1, RX1 and TX2, RX2 are in contact with the portion of the volar surface of the left wrist corresponding to the radial artery. In this state, the user closes and fixes the buckle 24. Thus, the blood pressure measuring device is worn on the user's left wrist.

FIG. 4 is a plan view illustrating each arrangement position of the pair of transmission / reception antennas TX1, RX1 and TX2, RX2 with respect to the radial artery 91 when the main body 10 is attached to the user's left wrist 90.

As shown in FIG. 4, in the mounted state, the pair of transmission / reception antennas TX1, RX1 and TX2, RX2 correspond to the position of the radial artery 91 of the left wrist 90 in the longitudinal direction of the left wrist 90 (width of the band 20). They are arranged at a certain distance apart (corresponding to the direction Y). Further, the transmitting antennas TX1 and TX2 and the receiving antennas RX1 and RX2 are arranged so as to be separated from each other along the circumferential direction of the left wrist 90 (corresponding to the longitudinal direction X of the band 20).

In this example, the transmitting antennas TX1 and TX2 and the receiving antennas RX1 and RX2 are either vertically or horizontally in terms of plane direction (meaning the direction of the paper in FIG. 4) so that radio waves having frequencies in the GHz band can be transmitted or received. Also has a square pattern shape of about 3 mm.

Further, the transmitting antennas TX1 and TX2 and the receiving antennas RX1 and RX2 may be provided with a conductor layer for transmitting radio waves along a surface facing the left wrist 90. In the mounted state, the conductor layer faces the palm side surface 90a of the left wrist 90, and the dielectric layer acts as a spacer to keep the distance between the palm side surface 90a of the left wrist 90 and the conductor layer constant. This makes it possible to accurately measure the biological information from the left wrist 90. The conductor layer is made of, for example, a metal (copper or the like), and the dielectric layer is made of, for example, polycarbonate.

Such transmitting antennas TX1 and TX2 and receiving antennas RX1 and RX2 are configured to be flat along the plane direction. Therefore, in this blood pressure measuring device, the band 20 can be formed to be thin as a whole.

Although FIGS. 3 and 4 exemplify a blood pressure measuring device provided with two sets of pulse wave sensors, the number of sensors is not limited to this. For example, three or more sets of pulse wave sensors may be dispersedly arranged along the radial artery 91, and the pulse waves may be measured at three or more positions of the radial artery by these pulse wave sensors. In this way, the number of measured pulse wave signals can be increased, so that the accuracy when calculating the pulse wave velocity (PTT), for example, can be improved. The pulse wave sensor is not limited to a plurality of sets and may be one set.

(2) Configuration Example of Circuit System of Blood Pressure Measuring Device FIG. 5 is a block illustrating the circuit configuration of the blood pressure measuring device.
The blood pressure measuring device includes a plurality of sensor units and a processing unit 12. In FIG. 5, for the sake of simplicity of illustration, the sensor units are shown as the first sensor unit 130-1 and the second to nth sensor units 130-2 to 130-n. For the sake of brevity, only the first sensor unit 130-1 and the second sensor unit 130-2 will be described, and the description of the other sensor units will be omitted.

The first sensor unit 130-1 and the second sensor unit 130-2 have a pair of the transmitting antenna TX1 and the receiving antenna RX1 and a pair of the transmitting antenna TX2 and the receiving antenna RX2, respectively. The transmitting antennas TX1 and TX2 and the receiving antennas RX1 and RX2 are both directional in the direction of the measurement site including the radial artery 91.

Further, the first sensor unit 130-1 and the second sensor unit 130-2 include a pair of the transmission circuit TC1 and the reception circuit RC1 and a pair of the transmission circuit TC2 and the reception circuit RC2, respectively. The transmitting circuit TC1 and the receiving circuit RC1 are connected to the transmitting antenna TX1 and the receiving antenna RX1, respectively, and the transmitting circuit TC2 and the receiving circuit RC2 are connected to the transmitting antenna TX2 and the receiving antenna RX2, respectively.

The transmission circuits TC1 and TC2 generate transmission waves at regular intervals and supply them to the transmission antennas TX1 and TX2, whereby radio waves generated by the transmission waves are transmitted from the transmission antennas TX1 and TX2 to the measured portion. In this example, radio waves (transmitted waves) E1 and E2 are transmitted toward the left wrist 90 (more accurately, the corresponding portion of the radial artery 91) as the measurement site. Further, the transmission circuits TC1 and TC2 generate a reference wave at the same timing as the transmission wave, and supply the reference wave to the pair of reception circuits RC1 and RC2. The transmitted wave and the reference wave will be described in detail below.

That is, the transmitted wave is composed of a short pulse burst wave. The pulse width PW of this burst wave has a range of distances that can be separated and identified by the distance resolution starting from the transmitting antennas TX1 and TX2, including the radial artery 91 as the measurement site, and is located far from the radial artery 91. It is set so that it does not include the object to be used.

For example, assuming that the object to be separated is an object having a distance of 30 cm or more from the transmitting antennas TX1 and TX2 (for example, the body of the user to be measured), the pulse width is set to 2 nsec. Further, when the separation target is assumed to be a peripheral object having a distance of 75 cm or more from the transmitting antennas TX1 and TX2 (for example, a structure such as another user's body, a pillar, a wall, or office equipment existing in the vicinity), a pulse is generated. The width is set to 5 nsec. The pulse width PW is set to a value according to the distance resolution of the setting target within the range of, for example, 5 nsec as the upper limit and 1 nsec as the lower limit.

Further, it is known that there is a correlation between the pulse width of the burst wave and the frequency bandwidth, and that the smaller the pulse width is, the wider the frequency bandwidth is required. Here, assuming that the frequency bandwidth of the burst wave is Δf and the speed of light is c, Δd = c / 2 / Δf between the frequency bandwidth Δf and the distance resolution Δd.
There is a relationship.

By utilizing this relationship, it is possible to obtain a desired distance resolution Δd by arbitrarily setting the frequency bandwidth Δf. For example, when the distance resolution Δd is set to the above 30 cm, the frequency bandwidth Δf is set to 0.5 GHz. When the distance resolution Δd is set to 75 cm, the frequency bandwidth Δf is set to 0.2 GHz.

As the center frequency of the burst wave, 7.25 to 1.25 GHz is selected as an example in order to maintain the pulse wave detection performance of a predetermined value or higher.

On the other hand, the receiving circuits RC1 and RC2 receive the reflected waves E1'and E2'by the radial artery 91 of the radio waves E1 and E2, respectively, via the receiving antennas RX1 and RX2. Further, the receiving circuits RC1 and RC2 introduce burst waves generated in the transmitting circuits TC1 and TC2 as reference waves FS1 and FS2, respectively. The burst waves serving as the reference waves FS1 and FS2 have the same frequency and the same pulse width as the burst waves generated as the transmission waves, and are generated at the same timing.

The receiving circuits RC1 and RC2 detect the received waveform signals RS1 and RS2 of the reflected waves E1'and E2'by the reference waves FS1 and FS2, thereby causing the reflected waves E1'and E2'and the reference waves FS1 and FS2. The received signals RS1'and RS2'indicating the phase difference between the two and the reception intensity of the reflected waves E1'and E2' are output. Then, the received signals RS1'and RS2' after this detection are amplified to, for example, the signal level required for A / D conversion, converted into a digital signal by an A / D converter, and output to the processing unit 12.

The processing unit 12 includes, for example, a hardware processor such as a central processing unit (CPU) and a storage unit, and as a processing function unit according to an embodiment, pulse wave detection units 101-1 and 101-2, ..., 101-n (101-1-101-n), a PTT calculation unit 103, a blood pressure estimation unit 104, and an output unit 105. All of these processing function units are realized by causing the hardware processor to execute a program stored in a storage unit (not shown).

The storage unit is configured by combining HDD (Hard Disk Drive), SSD (Solid State Drive), ROM, RAM, etc. as a storage medium, and controls a program for controlling the blood pressure measuring device and the blood pressure measuring device. Control data used for this purpose, setting data for setting various functions of the blood pressure measuring device, detection signals of pressure and pulse waves, data representing blood pressure measurement results, etc. are stored. The storage unit is also used as a work memory or the like when a program is executed.

The pulse wave detection units 101-1 and 101-2 take in the digitized reception signals RS1'and RS2' from the reception circuits RC1 and RC2, respectively. Then, the pulse wave signals PS1 and PS2 representing the pulsating waveform of the radial artery 91 are detected based on the received signals RS1'and RS2' that are taken in at regular time intervals. Then, the pulse wave signals PS1 and PS2 are output to the PTT calculation unit 103. The pulse wave detection units 101-1 and 101-2 may be realized by an analog circuit provided independently, in addition to being realized by software processing by the CPU.

The PTT calculation unit 103 calculates the time difference between the pulse wave signals PS1 and PS2 output from the pulse wave detection units 101-1 and 101-2 as the pulse wave velocity (PTT), and the calculated pulse wave velocity is calculated. The time (PTT) is output to the blood pressure estimation unit 104.

The blood pressure estimation unit 104 is based on, for example, the pulse wave velocity (PTT) calculated by the PTT calculation unit 103 and a correspondence formula stored in a storage unit (not shown) that expresses the relationship between the PTT and the blood pressure value. The blood pressure value corresponding to the calculated pulse wave velocity (PTT) is estimated. Then, the estimated value of blood pressure is output to the output unit 105.

The output unit 105 causes the display 50 shown in FIG. 3 to display the estimated value of the blood pressure output from the blood pressure estimation unit 104. As the display 50, for example, an organic EL (Electro Luminescence) display is used. The display 50 is not limited to the organic EL display, and may be another type of display such as a liquid crystal display (LCD) or a display using 7 segments.

The output unit 105 may have a function of storing, for example, the estimated value of blood pressure in a storage unit (not shown) or outputting it to an external device via a network. At that time, the estimated value of blood pressure may include information indicating the measurement date and time and other additional information such as the name of the user to be measured or the ID of the pulse wave measuring device, and further, the pulse wave detecting unit 101. When the pulse rate is detected by -1, 101-2 or the PTT calculation unit 103, this pulse rate may be included in the additional information.

(Operation example)
Next, an operation example of the blood pressure measuring device including the function as the pulse wave measuring device configured as described above will be described.
The CPU of the processing unit 12 instructs the transmission circuits TC1 and TC2 to start transmitting the transmission wave. Upon receiving the above instruction, the transmission circuits TC1 and TC2 generate short pulse burst waves at preset time intervals, and the generated burst waves are supplied to the transmission antennas TX1 and TX2 as transmission waves. To. At this time, the pulse width PW of each burst wave includes the radial artery 91, which is the measurement site, in the range of the distance that can be separated and identified by the distance resolution starting from the transmitting antennas TX1 and TX2, and is from the radial artery 91. It is set so that it does not include objects located in the distance. For example, as described above, the value is set according to the desired distance resolution within the range of, for example, 5 nsec as the upper limit and 1 nsec as the lower limit.

As a result, for example, as shown in FIG. 4, radio waves E1 and E2 generated by the above-mentioned transmitted waves are transmitted from the transmitting antennas TX1 and TX2 to different parts of the radial artery 91 in the blood flow direction. The transmitted wave may be generated from the transmission circuits TC1 and TC2 at regular time intervals, may be generated at irregular time intervals, and may be continuously generated. You may do so.

Then, the reflected waves E1'and E2'by the radial artery 91 of the radio waves E1 and E2 are received by the receiving antennas RX1 and RX2 as shown in FIG. 4, and the received waveform signals RS1 and RS2 are received by the receiving circuits RC1 and RC1. It is input to RC2. In the receiving circuits RC1 and RC2, the received waveform signals RS1 and RS2 of the reflected waves E1'and E2' are detected by the reference waves FS1 and FS2 output from the transmitting circuits TC1 and TC2, respectively. At this time, as the reference waves FS1 and FS2, burst waves having the same frequency and the same pulse width as the burst wave generated for transmitting the transmitted wave and generated at the same timing are used. Therefore, the detection provides a signal indicating the phase difference between the reflected waves E1'and E2'and the reference waves FS1 and FS2 and the reception intensity of the reflected waves E1'and E2'.

Moreover, the radio waves E1 and E2 as the transmitted waves include the radial artery 91 whose measurement site is the range of the distance that can be separated and identified by the distance resolution starting from the transmitting antennas TX1 and TX2, and from the radial artery 91. It consists of a short pulse-shaped burst wave in which the pulse width PW is set so as to be within a range that does not include an object located at a distance. Therefore, the received waveform signals RS _S of the reflected waves E1'and E2' by the radial artery 91 as the measurement site are detected by the reference waves FS1 and FS2 as shown in FIG. 6, and as a result, the receiving circuits RC1 and RC2 As a result, received signals RS1'and RS2' indicating the phase difference between the reflected waves E1'and E2'and the reference waves FS1 and FS2 and the reception intensity of the reflected waves E1'and E2' are obtained.

On the other hand, for example, the reception timing of the reflected wave by the user's body or surrounding objects located far from the radial artery 91 is the pulse of the burst wave constituting the radio waves E1 and E2 as the transmitted wave and the reference waves FS1 and FS2. It is out of the range of the distance that can be separated and identified by the distance resolution defined by the width PW. Thus, for example, as shown in FIG. 7, the received waveform signal RS _N of the reflected wave is not detected by the reference wave FS1, FS2, resulting received signal RS1 ', RS2' are not output.

The received signals RS1'and RS2' obtained by the above detection are further amplified to the signal level required for A / D conversion in the receiving circuits RC1 and RC2, converted into digital signals by the A / D converter, and processed. It is input to the unit 12.

The processing unit 12 captures the detected reception signals RS1'and RS2' output from the reception circuits RC1 and RC2, respectively, in the pulse wave detection units 101-1 and 101-2, respectively, and the pulse wave signals are as follows. Detects PS1 and PS2.

That is, the pulse wave detection unit 101-1 detects the pulse wave signal PS1 representing the pulse wave of the upstream portion of the radial artery 91 from the output of the receiving circuit RC1 in the diastole period and the output in the blood vessel systole period. Further, the pulse wave detection unit 101-2 detects the pulse wave signal PS2 representing the pulse wave in the downstream portion of the radial artery 91 from the output of the receiving circuit RC2 in the diastole period and the output in the blood vessel systole period.

The above operation will be described in more detail. That is, when the blood pressure measuring device is attached to the user's left wrist, as shown in FIG. 4, the pair of transmission / reception antennas TX1 and RX1 is It faces the upstream site of the radial artery 91 passing through the left wrist 90. On the other hand, the pair of transmission / reception antennas TX2 and RX2 faces the downstream portion of the radial artery 91.

The signal detected by the pair of transmitting and receiving antennas TX1 and RX1 is the change in the distance between the blood vessel surface at the upstream part of the radial artery 91 and the pair of the transmitting and receiving antennas TX1 and RX1, that is, the pulsation at the upstream part of the radial artery 91. Represents (dilation and contraction of blood vessels). Similarly, the signal detected by the pair of transmitting and receiving antennas TX2 and RX2 is the change in the distance between the blood vessel surface and the pair of transmitting and receiving antennas TX2 and RX2 at the downstream site of the radial artery 91, that is, the downstream side of the radial artery 91. Represents pulsation (dilation and contraction of blood vessels) at the site. The pulse wave detection unit 101-1 corresponding to the first sensor unit 130-1 and the pulse wave detection unit 101-2 corresponding to the second sensor unit 130-2 are based on the output signals of the receiving circuits RC1 and RC2, respectively. The first pulse wave signal PS1 and the second pulse wave signal PS2 each having a mountain-shaped waveform as shown in FIG. 4 are output in chronological order.

In this example, the reception level of the reception antennas RX1 and RX2 is about 1 μW (−30 dBm in decibel value with respect to 1 mW). The output level of the receiving circuits RC1 and RC2 is about 1 volt. Further, the peaks A1 and A2 of the first pulse wave signal PS1 and the second pulse wave signal PS2 are about 100 mV to 1 volt, respectively.

The processing unit 12 then operates as a PTT calculation unit 103 by executing an application program, and the pulse wave signal PS1 detected at the upstream site of the radial artery 91 and the pulse wave signal PS1 detected at the downstream site of the radial artery 91 are detected. The time difference between the pulse wave signal PS2 and the pulse wave signal PS2 is calculated as the pulse wave velocity (PTT).

In this example, the time difference Δt between the peak A1 of the first pulse wave signal PS1 and the peak A2 of the second pulse wave signal PS2 shown in FIG. 4 is calculated as the pulse wave propagation time (PTT). The pulse wave propagation time (PTT) is not limited to the time difference Δt between the peaks of the first and second pulse wave signals PS1 and PS2, and for example, the waveforms of the first and second pulse wave signals PS1 and PS2. It may be calculated as a time difference between the rise timings.

The processing unit 12 subsequently operates as a blood pressure estimation unit 104 by executing an application program, and reads out a relational expression (also referred to as a corresponding expression) Eq between the pulse wave velocity (PTT) and the blood pressure from the storage unit. Then, the estimated value of blood pressure is calculated based on the corresponding formula Eq and the pulse wave velocity (PTT) calculated by the PTT calculation unit 103. Here, the correspondence Eq between the pulse wave velocity (PTT) and the blood pressure is expressed as DT for the pulse wave velocity and EBP for the blood pressure, respectively, for example, EBP = α / DT2 + β ... (Eq.1).
(However, α and β represent known coefficients or constants, respectively)
It is provided as a known fractional function including the term 1 / DT2 as shown in. This corresponding formula is described in detail in, for example, Japanese Patent Application Laid-Open No. 10-201724.

In addition, as the correspondence Eq between the pulse wave velocity (PTT) and the blood pressure,
EBP = α / DT2 + β / DT + γDT + δ… (Eq.2)
(However, α, β, γ, and δ represent known coefficients or constants, respectively)
As described above, in addition to the 1 / DT2 term, another known corresponding expression such as an expression including the 1 / DT term and the DT term can be used.

When the blood pressure value is estimated by the pulse wave velocity (PTT), the processing unit 12 then compares the estimated blood pressure value with a preset threshold value representing a normal range of blood pressure, and is indicated by this threshold value. Determine if it is out of range. Then, if the estimated value of the blood pressure is within the range indicated by the threshold value, the measurement control is repeated until the operation unit 52 inputs an instruction to end the blood pressure measurement based on the pulse wave velocity (PTT).

Finally, the processing unit 12 outputs the estimated blood pressure value calculated by the blood pressure estimation unit 104 to the display 50 together with the additional information by the output unit 105 and displays it.

(Effect of one embodiment)
As described in detail above, in one embodiment, in order to measure the pulse wave, a transmission wave composed of a short pulse burst wave is generated in the transmission circuits TC1 and TC2, and this transmission wave is supplied to the transmission antennas TX1 and TX2. By doing so, the radio waves E1 and E2 are transmitted to the sites having different blood flow directions of the radial artery 91, which is the measurement site. At this time, the pulse width PW of the burst wave includes the radial artery 91, which is the measurement site, in the range of the distance that can be separated and identified by the distance resolution starting from the transmitting antennas TX1 and TX2, and is from the radial artery 91. It is set so that it does not include objects located in the distance. Then, in one embodiment, the reflected waves E1'and E2'by the radial artery 91 of the radio waves E1 and E2 are detected by the reference waves FS1 and FS2 in the receiving circuits RC1 and RC2, respectively. At this time, as the reference waves FS1 and FS2, burst waves generated in the transmission circuits TC1 and TC2 having the same frequency and pulse width as the burst wave as the transmission wave and at the same timing are used. Then, the received signals RS1'and RS2' after the detection are input to the pulse wave detection units 101-1 and 101-2 to detect the pulse wave representing the pulsation of the radial artery 91.

Therefore, according to one embodiment, the reflected waves E1'and E2' by the radial artery 91 located within the range of the distance that can be separated and identified by the distance resolution are detected by the reference waves FS1 and FS2, and the received signal after the detection. Is used to generate a pulse wave signal by the pulse wave detection units 101-1 and 101-2. On the other hand, since the noise sources such as the user's body and surrounding objects located farther than the radial artery 91 are outside the range of the distance that can be separated and identified by the distance resolution, the received waveform signal of the reflected wave by the noise source. RS _N is not detected by the reference waves FS1 and FS2. Therefore, the received waveform signal RS _N of the reflected waves by the noise source is input as a noise in the pulse wave detection section 101-1 and 101-2 is prevented. Therefore, it is possible to reduce the influence of the reflected wave due to the noise source such as the user's body and surrounding objects, and further improve the quality of the pulse wave signal.

Further, the pulse wave velocity (PTT) is calculated by the PTT calculation unit 103 based on the high-quality pulse wave signal in which the influence of the reflected wave by the noise source as described above is reduced, and the blood pressure value is calculated by the blood pressure estimation unit 104. By estimating, it is possible to further improve the accuracy of blood pressure measurement by the PTT method.

[Modification example]
(1) In the above embodiment, a case where the pulse width PW of the measurement signal is fixedly set to a certain value according to the required distance resolution has been described as an example. However, for example, the detection accuracy (S / N) of the pulse wave signal obtained by the pulse wave detection units 101-1 and 101-2 is estimated based on the measurement accuracy of the blood pressure value obtained by the blood pressure estimation unit 104, and the said The pulse width may be variably controlled in a direction of increasing the detection accuracy based on the estimated value of the detection accuracy.

The measurement accuracy of the blood pressure value estimated by the PTT method can be estimated by the difference from the blood pressure value measured by this oscillometric method, for example, by using the blood pressure measurement by the oscillometric method together. Further, for variable control of the pulse width PW, for example, a learning model is used, and an estimated value of blood pressure measurement accuracy by the PTT method or a pulse wave signal detection accuracy estimated from this estimated value is input to this learning model for learning. This can be realized by outputting the correction value of the pulse width or the data representing the corrected pulse width from the model. Further, the variable control of the pulse width can be realized by controlling the operation of the burst wave generation circuit with the switching function by the CPU.
By providing the variable pulse width control function in this way, it is possible to set the optimum pulse width PW according to the measurement environment of the user.

(2) In the above embodiment, the pair of transmission / reception antennas TX1, RX1 and TX2, RX2 are arranged so as to correspond to the width direction Y of the band 20, that is, the longitudinal direction of the radial artery 91, whereby blood pressure estimation by PTT is performed. The case of doing this was explained as an example. However, the present invention is not limited to this configuration, and only one transmission / reception antenna pair may be provided so as to detect the pulse wave at any one position of the radial artery 91. In this case, the blood pressure measuring device calculates the feature amount of the waveform of the pulse wave signal detected by the pair of transmission / reception antennas, and uses a formula or a memory table showing the relationship between the feature amount and the blood pressure value to perform the above calculation. The blood pressure is estimated by obtaining the blood pressure value corresponding to the feature amount.

(3) In the above embodiment, a case where the pair of transmission / reception antennas TX1, RX1 and TX2, RX2 are arranged along the longitudinal direction (Y direction) of the radial artery 91 at a predetermined interval has been described as an example. However, the present invention is not limited to this, and the pair of the transmission / reception antennas TX1, RX1 and TX2, RX2 are arranged at predetermined intervals in the direction orthogonal to the radial artery 91, that is, in the circumferential direction (X direction) of the band 20. You may. At this time, the set of the antenna boards may be one set, but a plurality of sets may be arranged at predetermined intervals in the X direction.

With the above configuration, the transmission and reception of the measurement signal and the reflected signal are performed at a plurality of positions in the direction orthogonal to the radial artery 91, respectively. Therefore, for example, even if there are individual differences in the position of the user's radial artery 91, or even if the mounting position of the band 20 with respect to the measurement site deviates in the X direction, at least one of the plurality of antenna substrates can be used. It is possible to bring it closer to the artery, which makes it possible to measure the pulse wave with good quality.

(4) In the above embodiment, a case where the blood pressure measuring device is provided with the function of the pulse wave measuring device, the pulse wave signal is detected, and the blood pressure value is measured by the PTT method based on the pulse wave signal has been described as an example. However, the blood pressure value may be estimated by a method other than the PTT method, or a device having only a pulse wave measurement function may be configured to measure only the pulse rate or analyze the pulse wave waveform. Other information may be obtained from the pulse wave, such as determining the cardiovascular condition of the user or authenticating the user's identity.

(5) In addition to the wearable type that is always worn on the wrist, the blood pressure measuring device is worn only at the time of measurement on other upper limbs such as the upper arm and lower limbs such as the thigh and ankle. May be good. At that time, the mounting position may be any position as long as the artery exists under the skin.

Although the embodiments of the present invention have been described in detail above, the above description is merely an example of the present invention in all respects. Needless to say, various improvements and modifications can be made without departing from the scope of the present invention. That is, in carrying out the present invention, a specific configuration according to the embodiment may be appropriately adopted.

In short, the present invention is not limited to the above-described embodiment as it is, and at the implementation stage, the components can be modified and embodied without departing from the gist thereof. In addition, various inventions can be formed by an appropriate combination of a plurality of components disclosed in the above-described embodiment. For example, some components may be removed from all the components shown in the embodiments. In addition, components from different embodiments may be combined as appropriate.

1 ... Transmitter 2 ... Receiver 3 ... Pulse wave detector 4 ... Artery 10 ... Main body 12 ... Processing unit 20 ... Band 40 ... Transmission / reception unit 130-1 ... First sensor unit 130-2 ... Second sensor unit TC1 , TC2 ... Transmission circuit RC1, RC2 ... Reception circuit TX1, TX2 ... Transmission antenna RX1, RX2 ... Reception antenna 50 ... Display 52 ... Operation unit 90 ... Left wrist 91 ... Radial artery 101-1, 101-2 ... Pulse wave detection Circuit 103 ... PTT calculation unit 104 ... Blood pressure estimation unit 105 ... Output unit

Claims (7)

A transmission unit that has a transmission circuit and a transmission antenna and transmits a transmission wave consisting of radio waves toward a part to be measured of a living body.
A receiving unit having a receiving circuit and a receiving antenna and receiving a reflected wave of the transmitted wave by the measured portion, and a receiving unit.
It is provided with a pulse wave detecting unit that detects a pulse wave signal representing the pulsation of the measured portion based on the signal output from the receiving unit.
The transmission circuit has a pulse width so that one of the range of distances that can be separated and identified by the distance resolution starting from the transmitting antenna includes the measured portion and does not include an object located at least far from the measured portion. Generates a short pulse burst wave in which is set, outputs the burst wave as the transmission wave to the transmission antenna, and outputs a reference wave generated at the same time as the transmission wave to the reception circuit.
The receiving circuit outputs a signal representing the phase difference between the reflected wave and the reference wave received by the receiving antenna to the pulse wave detection unit.
Pulse wave measuring device. In the transmission circuit, when the measurement site is the radial artery of the user's wrist, the range of the distance that can be separated and identified by the distance resolution is within the range that does not include the user's torso from the transmission unit. The pulse wave measuring device according to claim 1, wherein the pulse width is set. In the transmission circuit, when the measurement site is the radial artery of the user's wrist, the range of the distance that can be separated and identified by the distance resolution is within the range that does not include the object existing around the user from the transmission unit. The pulse wave measuring device according to claim 1, wherein the pulse width is set so as to be. When the distance resolution is Δd and the speed of light is c, the transmission circuit sets the frequency bandwidth Δf of the burst wave in order to set the pulse width corresponding to the range of the distance that can be separated and identified by the distance resolution. ,
Δd = c / 2 / Δf
The pulse wave measuring device according to claim 1, which is set to a value satisfying the relationship of. It is a pulse wave measurement method performed by a pulse wave measuring device that measures the pulsation of a part to be measured in a living body using radio waves.
The process of transmitting a transmitted wave composed of the radio waves from a transmitting unit having a transmitting circuit and a transmitting antenna toward the measured portion of the living body, and
The process of receiving the reflected wave of the transmitted wave by the measured portion by the receiving unit having the receiving circuit and the receiving antenna, and
Based on the signal output from the receiving unit, it includes a process of detecting a pulse wave signal representing the pulsation of the measured portion.
In the process of transmitting the transmitted wave, one of the range of the distance that can be separated and identified by the distance resolution starting from the transmitting antenna by the transmitting circuit includes the measured portion and is located at least far from the measured portion. A short pulse-shaped burst wave whose pulse width is set so as not to include an object is generated, the burst wave is output to the transmitting antenna as the transmitting wave, and a reference wave generated at the same time as the transmitting wave is generated. Output to the receiving circuit
In the process of receiving the reflected wave, the receiving circuit outputs a signal representing the phase difference between the reflected wave and the reference wave received by the receiving antenna to the pulse wave detection unit.
Pulse wave measurement method. The pulse wave measuring device according to claim 1 is provided with at least one set.
The at least one set of pulse wave measuring devices is attached to the living body so as to be arranged to face the artery as the measurement site.
A blood pressure estimator connected to the at least one set of pulse wave measuring devices is provided.
The blood pressure estimation unit
A calculation unit that calculates the feature amount of the waveform of the pulse wave signal based on the pulse wave signal corresponding to the measurement site detected by the pulse wave detection unit of at least one set of pulse wave measurement devices.
An estimation unit that estimates the blood pressure value corresponding to the calculated feature amount based on the relational expression between the feature amount and the blood pressure value stored in the memory in advance.
A blood pressure measuring device having an output unit that outputs the estimated blood pressure value. When two sets of the pulse wave measuring devices are provided,
The two sets of pulse wave measuring devices are attached to the living body so as to be arranged so as to face the first site of the artery as the measurement site and the second site on the downstream side of the first site.
The blood pressure estimation unit
As feature quantities of the waveform, a first pulse wave signal corresponding to the first portion detected by each pulse wave detection unit of the two sets of pulse wave measuring devices and a second pulse wave signal corresponding to the second portion. The pulse wave propagation time between the first part and the second part is calculated based on the pulse wave signal of
Based on the relational expression between the pulse wave velocity and the blood pressure value stored in the memory in advance, the blood pressure value corresponding to the calculated pulse wave velocity is estimated.
The blood pressure measuring device according to claim 6.