JP6963293B2 - Heart rate / respiration measurement system and heart rate / respiration measurement method - Google Patents

Description

The present invention relates to a heartbeat / respiration measurement system that measures the heartbeat and respiration of a subject in a non-contact manner, and a heartbeat / respiration measurement method.

Conventionally, a device for measuring heartbeat and respiration using a radar without contact with a subject has been proposed.
For example, Patent Document 1 describes a measuring device that irradiates a subject with microwaves and measures the respiratory rate and heart rate using the reflected waves.
The technique described in Patent Document 1 can diagnose a subject's condition with extremely little burden on the subject by measuring the respiratory rate and heart rate without touching the subject. That is, since the subject can unconsciously measure the respiratory rate and the heart rate, it is possible to expand the application for diagnosing the subject. For example, in a facility where an elderly person lives, if the respiratory rate and heart rate of a subject sleeping in a bed can be constantly measured in a non-contact manner, sleep disorders and heart abnormalities can be appropriately detected.

Japanese Unexamined Patent Publication No. 2009-172176

A conventional respiratory rate or heart rate measuring device using a radar separates the signal reflected from the subject into each frequency component by performing a fast Fourier transform (FFT), and corresponds to the frequency component corresponding to the breath and the heart rate. The frequency component was acquired. In other words, the respiratory rate and heart rate were obtained from each frequency component. When the FFT is used, the target frequency component can be accurately extracted, which is preferable from the viewpoint of improving the measurement accuracy, but there is a problem that the circuit for executing the FFT calculation has a complicated configuration. Therefore, there is a problem that the measuring device becomes complicated and large, and the power consumption increases.

In the conventional measuring device that performs arithmetic processing using the FFT, there is a limit to miniaturization and low power consumption. In addition, since multiple wavelength components are required for each frequency component in order to perform FFT calculation, the measured respiratory rate and heart rate are values that immediately indicate the real-time state of the subject. I can not say.
Specifically, the normal value of the respiratory rate is about ten and several times per minute. For example, assuming that there are 10 breaths per minute, one breath is 6 seconds, and the signal of that one breath is 6 seconds is FFT. It was necessary to acquire a measurement signal of several tens of seconds in order to acquire multiple wavelengths in order to perform the calculation of.

Therefore, it is difficult for a measuring device that performs FFT calculation to immediately detect the respiratory cycle from, for example, a short-time measurement signal corresponding to one breath.
On the other hand, if it is possible to reduce the size and power consumption of the device by using a device that measures the respiratory rate and heart rate in a non-contact manner, it will be possible to measure the heart rate and breathing on a daily basis at home. In that respect, the use of the measuring device may be expanded.

An object of the present invention is to enable non-contact measurement of heartbeat and respiration to be performed in near real time with a simple and low power consumption configuration.

The heart rate / respiration measurement system of the present invention extracts a frequency band including a heartbeat component and a frequency band including a respiration component from a Doppler radar that receives a reflected wave of a radio wave radiated to a subject and a signal received by the Doppler radar. The frequency band containing the respiratory component is extracted from the first filter and the heartbeat component and the respiratory component extracted by the first filter, and the frequency band including the heartbeat component is removed by the second filter and the first filter. A subtractor that extracts the heartbeat component by subtracting the frequency component extracted by the second filter from the obtained heartbeat component and the respiratory component, and a signal containing the respiratory component extracted by the second filter are digitally converted. , A digital converter that digitally converts the signal containing the heartbeat component extracted by the subtractor, a data processing unit that analyzes the signal converted by the digital converter and obtains the measurement results of the subject's heartbeat and respiration. Ru equipped with. Then, the data processing unit detects the valley of the waveform that fluctuates in response to respiration, detects one respiration period, further detects the inspiratory period and the expiratory period of one respiration period, and detects one heartbeat during the inspiratory period. When the average period of one heartbeat detected during the inspiratory period is shorter than the average period of one heartbeat detected during the expiratory period by comparing the average period of one heartbeat detected during the expiratory period. , The heartbeat detected in the corresponding one breathing period is judged to be an appropriate measurement result.

Further, in the heartbeat / respiration measurement method of the present invention, the reflected wave of the radio wave radiated to the subject is obtained by the Doppler radar, and the frequency band including the heartbeat component and the frequency band including the respiration component are obtained from the obtained received signal. A second filter that extracts a frequency band containing a respiratory component from the first filtering process to be extracted and the heartbeat component and the respiratory component extracted by the first filtering process, and removes the frequency band containing the heartbeat component. In the processing, the subtraction process for extracting the heartbeat component by subtracting the frequency component extracted in the second filter process from the heart rate component and the respiratory component extracted in the first filter process, and the second filter process. The extracted signal is digitally converted, and the digital conversion process that digitally converts the signal extracted by the subtraction process and the signal converted by the digital conversion process are analyzed to obtain the measurement results of the subject's heartbeat and breath. and data processing, the including. Then, in the data processing, the valley of the waveform that fluctuates in response to respiration is detected to detect one respiration period, and the inspiration period and expiration period of one respiration period are detected, and the one heartbeat detected in the inspiration period is detected. Comparing the average period with the average period of one heartbeat detected during the expiratory period, when the average period of one heartbeat detected during the inspiratory period is shorter than the average period of one heartbeat detected during the expiratory period. The heartbeat detected during the corresponding one breathing period is judged to be an appropriate measurement result.

According to the present invention, it is possible to provide a compact and inexpensive system capable of capturing a subject's respiration and minute movements associated with the heartbeat and measuring the heart rate and the respiration rate quickly and accurately without contact.

It is a block diagram which shows the whole structure of the heart rate / respiration measurement system by the example of one Embodiment of this invention. It is a block diagram of the Doppler radar by one Embodiment of this invention. It is a circuit diagram of the analog signal processing part of the heart rate / respiration measuring apparatus according to the example of one Embodiment of this invention. It is a characteristic figure which shows the example of the pass band of each filter by the example of one Embodiment of this invention. Is a waveform diagram showing an output waveform V _I of the first band-pass filter according to an exemplary embodiment, an example of the second band-pass filter output waveform (signal of the respiratory component) V _RRI of the present invention. _{It is a waveform diagram which shows the waveform of the signal V RRI} , V _RRQ of the respiratory component according to the example of one Embodiment of this invention, and the example of the discriminant state of inspiration and exhalation. Is a waveform diagram showing an example of the heartbeat components included according to an exemplary embodiment the output waveform V _I of the first band-pass filter of the present invention. It is a waveform diagram which shows the example of the output waveform (signal of the heartbeat component) V _{HR of the subtractor according to the example of one Embodiment of this invention.} It is a flowchart which shows the detection processing example of heartbeat and respiration by one Embodiment of this invention. It is a waveform figure which shows the example of the detection state of the heartbeat in the expiratory period and the inspiratory period and each period by the example of one Embodiment of this invention. It is a block diagram which shows the whole structure of the heart rate / respiration measurement system by the example of another Embodiment of this invention. It is a characteristic diagram which shows the example of the pass band of each filter by the example of FIG.

Hereinafter, an example of an embodiment of the present invention (hereinafter, referred to as “this example”) will be described with reference to FIGS. 1 to 10.
[1. Overall configuration of heart rate / respiration measurement system]
FIG. 1 is a block diagram showing the overall configuration of the heart rate / respiration measurement system of this example.
The system of this example includes a heart rate / respiration measuring device 100, a display device 200, and a recording device 300. A Doppler radar 10 is connected to the heart rate / respiration measuring device 100, and the heart rate and respiration rate of the subject are measured by the heart rate / respiration measuring device 100 from the received signal obtained by the Doppler radar 10.

The Doppler radar 10 transmits a transmission signal Tx in a predetermined frequency band to the subject, and acquires the signal reflected by the subject as a reception signal Rx. The received signal Rx is supplied to the heart rate / respiration measuring device 100. In this case, the received signal Rx includes a real number component (I signal) and an imaginary number component (Q signal). A configuration example of the Doppler radar 10 will be described later (FIG. 2).

The heart rate / respiration measuring device 100 separately processes the I signal and the Q signal obtained from the Doppler radar 10 as analog signals, and includes the respiration signals V _RRI and V _RRQ containing the respiration component and the heart rate component. heartbeat signals _{V HRI,} obtain and _{V HRQ.} The reference value of the 1-minute respiratory rate of a normal adult is around 12 to 16 times, and the reference value of the 1-minute heart rate is 50 to 90 times. As the respiratory component and the heart rate component described in the present specification, the respiratory rate and the heart rate when there is an abnormality are detected as a frequency range having a certain range from these reference ranges.
The I signal processing system and the Q signal processing system have the same configuration. In FIG. 1, for the processing unit that processes the I signal, "I" is added to the end of the code to process the Q signal. Is indicated by adding "Q" to the end of the code. Although the configuration for processing the I signal will be described here, the Q signal is also processed in the same manner.

The I signal supplied from the Doppler radar 10 is amplified by the amplifier 101I and then supplied to the first filter 102I. The first filter 102I is a bandpass filter that performs a second filter process for extracting a frequency band including a respiratory component and a heartbeat component from the I signal. In the first filter 102I, a low frequency band and a high frequency band are removed from the frequency band including the respiratory component and the heartbeat component. As a specific example of the first filter 102I, for example, a bandpass filter that extracts a band from 0.159 Hz to 3.18 Hz is used.

The output signal _{V I} of the first filter 102I is supplied to the second filter 103I. The second filter 103I is a band-pass filter for performing a second filtering process that extracts a band including a respiratory component from the output signal V _I. The second filter 103I removes a low frequency band and a high frequency band from the frequency band including the respiratory component. As a specific example of the second filter 103I, for example, a bandpass filter that extracts a band from 0.159 Hz to 0.221 Hz is used.
The second filter 103I, a signal including the respiratory component respiration signal _{V RRI} is obtained. Respiration signal _{V RRI} second filter 103I outputs are supplied to an analog / digital converter 111I, digital conversion processing is performed. Then, the digitally converted data is supplied to the data processing unit 113.

The output signal _{V I} of the first filter 102I is supplied to the subtracter 105I. Then, the subtracter 105I, the output signal subtracted from _{V I} respiration signal _{V RRI} is subtracted is performed, the heart rate signal _{V HRI} is a signal including a heartbeat ingredient. In this case, the breathing signal _{V RRI} second filter 103I is output on the phase change by the second filter 103I by the phase corrector 104I is corrected, it is supplied to the subtracter 105I.
Subtractor heartbeat signal obtained by 105I _{V HRI} is converted into digital data by an analog / digital converter 112I, supplied to the data processing unit 113. Although the description is omitted, the Q signal is processed in the same manner as the I signal.

The thus obtained respiration signal _{V RRI, V RRQ} and heart signals _{V HRI, V HRQ} the separate analog / digital converters 111I, and converted 111Q, 112I, into digital data by the 112Q, the data processing unit 113 Is supplied to. In FIG. 1, four analog / digital converters 111I, 111Q, 112I, and 112Q are configured as separate converters. For example, one analog / digital converter is used to use four signals V _RRI and V _RRQ. , V _HRI , V _HRQ may be converted into digital data.

The data processing unit 113, the digital data is converted into a respiratory signal _{V RRI, V RRQ} and heart signals _{V HRI,} performs analysis processing of the _{V HRQ,} measures the respiratory rate and heart rate. The details of the analysis process performed by the data processing unit 113 will be described later.
The respiration rate and the heart rate obtained as the analysis result in the data processing unit 113 are displayed on the display device 200 connected to the heart rate / respiration measurement device 100. Further, a recording device 300 is connected to the heart rate / respiration measuring device 100, and the respiratory rate and the heart rate as the analysis result are recorded in the recording device 300.
In FIG. 1, the display device 200 and the recording device 300 are directly connected to the heart rate / respiration measurement device 100. For example, the heart rate / respiration measurement device 100 is provided with a wireless transmission unit and is wirelessly connected to the wireless transmission unit. The transmitted respiratory rate and heart rate information may be displayed or recorded by an external device.

[2. Doppler radar configuration]
FIG. 2 shows a configuration example of the Doppler radar 10.
The Doppler radar 10 includes an oscillator 11. The oscillator 11 oscillates, for example, a 24 GHz signal. The oscillation signal output by the oscillator 11 is supplied to the transmitting antenna 13 via the demultiplexer 12, and the transmission signal Tx is transmitted to the subject. Then, the received signal Rx as the reflected wave reflected on the body surface of the subject is received by the receiving antenna 14.

The received signal Rx obtained by the receiving antenna 14 is directly supplied to the first mixer 15, and the signal shifted by π / 2 (90 °) by the π / 2 phase shifter 17 is supplied to the second mixer 18. Then, the oscillation signal from the oscillator 11 is supplied to the first mixer 15 and the second mixer 18 via the duplexers 12 and 16, and the Doppler output is obtained by the respective mixers 15 and 18. The Doppler output obtained by the first mixer 15 becomes an I signal, and the Doppler output obtained by the second mixer 18 becomes a Q signal.

According to the results of experiments conducted by the inventors, the displacement of the body movement due to respiration was 4 to 12 mm, and the displacement of the body movement due to the heartbeat was 0.2 to 0.5 mm. The Doppler radar 10 is a device that detects the displacement of body movement due to these respirations and heartbeats in a non-contact manner. That is, when the distance from the Doppler radar 10 to the body surface of the subject and the d _0, processing the distance d ₀ of the displacement of the body motion due to breathing and heart rate changes, detects a change of the distance d ₀ from the received signal Is done.
It should be noted that the use of the 24 GHz band as the Doppler radar 10 is an example, and the Doppler radar that transmits signals in other frequency bands may be used. For example, it may be a Doppler radar using a 10 GHz band.

[3. Filter configuration and characteristics of heart rate / respiration measuring device]
FIG. 3 is a circuit diagram showing the configurations of a first filter (bandpass filter) 102I and a second filter (bandpass filter) 103I for processing the I signal of the heart rate / respiration measuring device. The first filter 102Q and the second filter 103Q that process the Q signal also have the same configuration as the first filter 102I and the second filter 103I shown in FIG.

The negative side input end of the operational amplifier 121 is connected to the input terminal 102a of the first filter 102I, which is a bandpass filter, via a series circuit of the capacitor C1 and the resistor R1. Further, the negative input end of the operational amplifier 121 is connected to the ground potential portion via a parallel circuit of the resistor R2 and the capacitor C3.
Further, a resistor R4 is connected between the + side input end and the output end of the operational amplifier 121, and a resistor R3 is connected between the + side input end of the operational amplifier 121 and the ground potential portion. .. The signal obtained at the output terminal of the operational amplifier 121 is taken out from the terminal 102b as an output signal of the first filter 102I and is supplied to the second filter 103I.

In the second filter 103I, which is a bandpass filter, the negative side input end of the operational amplifier 122 is connected to the input portion connected to the first filter 102I via a series circuit of the capacitor C4 and the resistor R5. Further, the negative input end of the operational amplifier 122 is connected to the ground potential portion via a parallel circuit of the resistor R6 and the capacitor C5.
Further, a resistor R8 is connected between the + side input end and the output end of the operational amplifier 122, and a resistor R7 is connected between the + side input end of the operational amplifier 122 and the ground potential portion. Then, the signal obtained at the output end of the operational amplifier 122 is taken out from the terminal 103a as the output signal of the second filter 103I.

FIG. 4 is a diagram showing the passing characteristics of the first filter 102I and the second filter 103I. In FIG. 4, the horizontal axis represents the frequency [Hz] and the vertical axis represents the attenuation [dB].
Here, in the first filter 102I, which is a bandpass filter, the lower limit frequency f _L1 of the pass band Fa is 0.159 Hz, and the upper limit frequency f _H1 of the pass band is 3.18 Hz. The lower limit frequency f _L1 of the first filter 102I is determined by the constants of the capacitor C1 and the resistor R1, and the upper limit frequency f _H1 is determined by the constants of the capacitor C3 and the resistor R2.

Further, in the second filter 103I, which is a bandpass filter, the lower limit frequency f _L2 of the pass band Fb is set to 0.159 Hz, and the upper limit frequency f _H2 of the pass band is set to 0.221 Hz. The lower limit frequency f _L2 of the second filter 103I is determined by the constants of the capacitor C4 and the resistor R5, and the upper limit frequency f _H2 is determined by the constants of the capacitor C5 and the resistor R6.
The characteristic Fc shown in FIG. 4 is a comprehensive characteristic that has passed through the two filters 102I and 103I. _{Respiratory signals V RRI} and V _RRQ are obtained as signals that have passed through these two filters 102I and 103I. The band Dr shown in FIG. 4 is a band containing a respiratory component, and the band Dh is a band containing a heartbeat component.

[4. Example of detected signal]
Figure 5 shows an output signal _{V I} of the first filter 102I, an example of respiration signals _{V RRI.} The horizontal axis of FIG. 5 represents time (seconds), and the vertical axis represents voltage (V).
As shown in FIG. 5, the output signal V _I of the first filter 102I, contains the respiratory component and the cardiac component. Then, the respiration signal V _RRI that has passed through the second filter 103I, heartbeat components are removed, variation in the amplitude in association with the breathing becomes to appear clearly.

FIG. 6 shows an example of the respiration signal V _{RRI obtained from the I signal, the respiration signal V RRQ} obtained from the Q signal, _{and the respiration signal V x} obtained from the measuring instrument attached to the human body of the subject. The measuring instrument attached to the human body of the subject is a type that measures respiration by attaching it directly on the skin using a belt, and the respiration signals V _RRI and V _{RRQ obtained by the heart rate / respiration measuring device of this example.} And for comparison, the respiratory signal V _x obtained with a conventional measuring instrument is shown.

_{As shown in FIG. 6, the respiration signals V RRI} and V _RRQ obtained by the heart rate / respiration measuring device of this example all showed the respiration state of the subject in the same manner as the _{respiration signal V x} obtained by the conventional measuring device. It is a signal, and it can be seen that the respiration rate can be measured satisfactorily by the heart rate / respiration measurement device of this example.
The data processing unit 113 of the heart rate / respiration measuring device of this example _{has timings t a} , t _b , t _c , t _d , _{which are valleys of the voltage waveform of the respiration signal VRRI} (the lowest level position in FIG. 6).・ ・ Is detected, and the section separated by the detected valley is determined as one breath. Specifically, the data processing unit 113, for example, the timing t 1 breath between _a timing t _b, while the next one breath, one single breath and so the timing t _b and the timing t _c Judge the period in order.

Then, the data processing unit 113 defines the period in which the voltage in the first half is higher than the valley as the inspiratory period (the period during which the lungs are inhaled) among the respective breathing periods detected based on the valley of the voltage waveform. , The period during which the voltage in the latter half decreases toward the valley is determined as the exhalation period (the period during which the lungs exhale). In the example of FIG. 6, of the two respiratory signals V _RRI and V _{RRQ , an example in which the respiratory period is detected from the respiratory signal V RRI} obtained from the I signal is shown, but the respiratory signal V obtained from the Q signal is shown. _The respiratory period may be detected from the RRQ.

7 and 8 show the output signal _{V I} of the first filter 102I (FIG. 7), an example of the heartbeat signal _{V HRI} (Figure 8). In FIGS. 7 and 8, the horizontal axis represents time (seconds) and the vertical axis represents voltage (V).
As shown in FIG. 7, the output signal V _I of the first filter 102I is a voltage in conjunction with the cycle of respiration of the subject up and down, also includes the heart rate component voltage minutely up and down. That is, within one breathing period, the voltage fluctuates in conjunction with the heartbeat, and peaks t ₁ , t ₂ , t ₃ , ..., Which are the highest positions of the fluctuating components, appear.
Then, as shown in FIG. 8, the heartbeat signal _{V HRI} obtained by the subtractor 105I is removed frequency component corresponding to the respiratory, peak _t 1 _heartbeat, t _{2, t} 3, · · · clarification It is a signal that has been used. The data processing unit 113 performs processing for determining the heartbeat from the _{peaks t 1} , t ₂ , t _{3, ....} That is, the data processing unit 113 performs processing using the peaks t ₁ , t ₂ , t _{3 , ... Detected from the heartbeat signal V HR as} the timing of the heartbeat.

[5. Breathing and heartbeat judgment processing]
FIG. 9 is a flowchart showing an example of respiration and heartbeat determination processing performed by the data processing unit 113. Here, it is assumed that the respiration and the heartbeat are determined by using _{the respiration signal V RRI} and the heartbeat signal V _{HR obtained from the I signal.}
First, the data processing unit 113 _{acquires the respiratory signal V RRI} and the heartbeat signal V _HR, and is based on the peak detection of the respiratory signal V _{RRI (detection of t 1} , t ₂ , t ₃ , ... As shown in FIG. 8). The heartbeat is detected and the respiration is detected from the valley of the _{respiration signal VRRI (step S11).}
Then, the data processing unit 113 _{determines whether or not the respiration signal VRRI} for one respiration period has been input (step S12). That is, the data processing unit 113, in the example shown in FIG. 6, for example, 2 valleys t _a, the detection of t _b, respiration signal V _RRI of one respiratory period is determined to have been entered. If it is determined in step S12 that the respiratory signal _VRRI for one breathing period has not been input (NO in step S12), the data processing unit 113 returns to the detection process in step S11.

Then, it is determined in step S12, 1 when breathing period of the respiration signal _{V RRI} is determined to have been input (YES in step S12), the data processing unit 113, 2 valleys (e.g. _t a shown in FIG. 6, _{t b} ), The inspiratory period, which is the section where the level of the respiratory signal V _RRI is high, and the expiratory period, which is the section where the level of the _{respiratory signal V RRI is low, are discriminated.} Then, the data processing unit 113 determines the ratio of the average length of one heartbeat detected during the inspiratory period to the average length of one heartbeat detected during the expiratory period (step S13).
That is, the data processing unit 113 calculates the average length of one heartbeat detected during the inspiratory period and the average length of one heartbeat detected during the expiratory period, compares the average lengths of each, and inhales. The ratio of the average length of one heartbeat during the period to the average length of one heartbeat during the expiratory period is determined.

Next, the data processing unit 113 determines whether or not the average length of one heartbeat during the inspiratory period is shorter than the average length of one heartbeat during the expiratory period (step S14). In this determination, when the average length of one heartbeat during the inspiratory period is shorter than the average length of one heartbeat during the expiratory period (YES in step S14), the data processing unit 113 determines that the heartbeat detection is appropriate. Judgment is made, and the measurement data of the heartbeat within one breathing period is taken in. Then, a process of obtaining the heart rate measurement data from the heart rate measurement data is performed (step S15). The state in which the average length of one heartbeat during the inspiratory period is shorter than the average length of one heartbeat during the expiratory period is a phenomenon called respiratory arrhythmia.
The heart rate measurement data is converted into, for example, a one-minute heart rate, displayed on the display device 200, and recorded on the recording device 300.

Further, in the determination in step S14, the average length of one heartbeat during the inspiratory period is equal to the average length of one heartbeat during the expiratory period, or the average length of one heartbeat during the inspiratory period is the exhalation. If it is longer than the average length of one heartbeat in the period (NO in step S14), the data processing unit 113 determines that the heartbeat is not detected correctly, and uses the measurement data in the corresponding one breathing period as the measured value. No error processing is performed (step S16). After the processing of steps S15 and S16, the process returns to the processing of step S11.

FIG. 10 shows an example of the detection of the inspiratory period and the expiratory period and the timing of the heartbeat detected in each period. 10A shows an example of a respiration signal _{V RRI,} FIG. 10B shows an example of the signal _{V I} that contains heartbeat components. The detection of heart rate is performed by the heartbeat signal V _HRI retrieving the heartbeat component from the signal V _I.
In the example shown in FIG. 10B, the data processing unit 113 determines, for example timing _{t 1,} t 2, heart rate detected in _{t 3} is the heart rate detected in the inspiratory period. Also, judges that the time _{t 4, t 5, t 6} , heart rate detected in t 7, _{t 8} is the heart rate detected in the exhalation period. Then, based on this determination, the data processing unit 113 executes the processes of steps S14 to S16.

In the description of the flowchart of FIG. 9, the data processing unit 113 obtains the respiratory _{rate and the heart rate from the respiratory signal V RRI} and the heart rate signal V _HR obtained from the I signal, but the respiratory signal obtained from the Q signal. For V _RRQ and heart rate signal V _HRQ , the respiratory rate and heart rate may be obtained by the same processing. In this case, for example, the data processing unit 113 compares the measured value obtained from the I signal with the measured value obtained from the Q signal, and outputs a measured value considered to be appropriate to the display device 200 and the recording device 300. Respiratory rate and heart rate to be performed. For example, even if the error processing in step S16 is performed in the judgment processing using the I signal, if the processing for obtaining the heart rate measurement data in step S15 can be obtained in the judgment processing using the Q signal, Q Adopt the measurement result by the signal.
Further, the heartbeat signal _{V HRI,} for _{V HRQ,} since variation in voltage based on the heart rate is relatively small, the data processing from any of the heartbeat signal _{V HRQ} obtained from the heartbeat signal _{V HRI} and Q signals obtained from the I signal There may be a temporary period during which the heartbeat cannot be detected in part 113. In such a case, interpolation or the like is performed from the detection state before and after the undetectable period to obtain an appropriate heart rate. When performing this interpolation, the data processing unit 113 determines whether the period during which the heartbeat cannot be detected temporarily is the inspiratory period or the expiratory period, and performs interpolation processing suitable for each period. By performing the above, it becomes possible to determine the heart rate more appropriately.

As described above, according to the heartbeat / respiration measurement system of this example, the respiration and heartbeat of the subject (patient) can be satisfactorily measured without contact. That is, in the case of this example, if a signal of at least one breathing period can be obtained, the period of one breathing period and the period of one heartbeat can be known, and the respiratory rate and the heart rate can be obtained. This makes it possible to obtain respiratory rate and heart rate in a very short time compared to those that required signals for at least multiple respiratory periods when performing FFT calculations in the past, and breathing in near real time. It has the effect of measuring the number and heart rate.
Moreover, in the case of this example, since the heartbeat and breathing can be measured at the same time, a phenomenon called respiratory arrhythmia, that is, a phenomenon in which the heartbeat becomes faster when inhaling and slows when exhaling, is confirmed. Therefore, when the phenomenon of respiratory arrhythmia appears, it is treated as if the respiratory rate and the heart rate can be measured correctly, which has an effect of obtaining accurate measurement data.

Further, since the heart rate / respiration measurement system of this example has a simple configuration that does not require complicated arithmetic processing such as FFT, it is possible to reduce the size and price of the heart rate / respiration measurement system. Furthermore, since it has a simple configuration that does not require complicated arithmetic processing, the power consumption of the heartbeat / respiration measurement system can be reduced, and for example, a heartbeat / respiration measurement system that can be continuously driven by a battery for a long time can be obtained. ..

[6. Examples of other embodiments (examples using a low-pass filter)]
FIG. 11 shows an example of another embodiment of the heart rate / respiration measurement system.
In the example shown in FIG. 11, a low-pass filter is used instead of the band-pass filter as the second filters 103I'and 103Q' provided in the heart rate / respiration measuring device 100.
That is, as shown in FIG. 11, as the processing system of the I signal, the output signal _{V I} of the first filter 102I, 'supplied to the second filter 103I' second filter 103I is a low pass filter includes heartbeat components The high frequencies are removed and the low frequencies containing the respiratory components are passed to obtain the respiratory signal _VRRI . Then, the respiration signal _{V RRI} obtained by the second filter 103I 'and supplied to an analog / digital converter 111I, and converted into digital data, and supplies the converted digital data to the data processing unit 113. Also, the respiration signal _{V RRI} obtained by the second filter 103I ', supplied to the subtracter 105I through the phase corrector 104I. Then, by subtracting the respiration signal _{V RRI} from the output signal _{V I,} to obtain a heartbeat signal _{V HRI,} and supplies the heart rate signal _{V HRI} analog / digital converter 112I, and converted into digital data, converted digital Data is supplied to the data processing unit 113.

Similarly, the processing system of the Q signal, the output signal V _Q of the first filter 102Q, 'supplied to the second filter 103Q' second filter 103Q is a low pass filter the high frequency is removed that contains the heartbeat component , The low-pass filter containing the respiratory component is passed to obtain the respiratory signal V _RRQ , and the subtractor 105Q is _used to obtain the heartbeat signal V HRQ.
In the case of the example of FIG. 1, the phase correctors 104I and 104Q correct the phase delay due to the second filter (bandpass filter) 103I and 103Q, whereas in the case of the example of FIG. 11, the phase correction is performed. The instruments 104I and 104Q correct the phase lag in the second filter (low-pass filter) 103I'and 103Q'.

FIG. 12 is a diagram showing the passing characteristics of the first filter 102I and the second filter 103I'. In FIG. 12, the horizontal axis represents the frequency [Hz] and the vertical axis represents the attenuation [dB].
Here, in the first filter 102I, the lower limit frequency f _L1 of the pass band Fa is 0.159 Hz, and the upper limit frequency f _H1 of the pass band is 3.18 Hz. The characteristics of the first filter 102I are the same as those shown in FIG.
Further, the second filter 103I'sets the upper limit frequency (cutoff frequency) f _H2 of the pass band Fb' to 0.221 Hz, and passes frequencies below it.
The characteristic Fc'shown in FIG. 12 is a comprehensive characteristic that has passed through the first filter 102I and the second filter 103I'. _{Respiratory signals V RRI} and V _RRQ are obtained as signals that have passed through the first filter 102I and the second filter 103I'.

As can be seen from the characteristics shown in FIG. 12, it can be a combination of the band-pass filter and the low-pass filter, the respiratory signal _{V RRI, V RRQ} a Oyobi heartbeat signal _{V HRI,} also possible to obtain the _{V HRQ.} The second filters 103I'and 103Q', which are low-pass filters, have the characteristic of allowing components in the lower range than the band Dr containing the respiratory component to pass through, but the first filter is the first for the components in the band lower than this band Dr. Since it has already been removed by the filters 102I and 102Q, almost the same performance as the example of FIG. 1 can be obtained.

[7. Modification example]
In the above-described embodiment, the Doppler radar 10 is used to transmit a frequency signal of 24 GHz. This transmission frequency is an example, and a Doppler radar that transmits other frequency signals such as 10 GHz may be used.

Further, the pass band of the first filter (bandpass filter) and the second filter (bandpass filter or lowpass filter) shown in FIGS. 4 and 12 is also an example, and other as the upper limit frequency and the lower limit frequency of the pass band. It may be a frequency. However, the frequency band including the respiratory component and the frequency band itself including the heartbeat component are fixed bands, and even if the upper limit frequency and the lower limit frequency are changed, the values in the vicinity of the frequencies described in the above-described embodiment example are used. Is preferable.
Further, a suitable example is shown for the specific circuit of each filter shown in FIG. 3, and a filter having another circuit configuration may be used.

Further, in the above-described embodiment, both the I signal (real number component) and the Q signal (imaginary number component) obtained by the Doppler radar 10 are filtered, and the respiratory component and heartbeat component of the I signal and the Q signal are filtered. I tried to obtain both the respiratory component and the heartbeat component of. From the viewpoint of improving the measurement accuracy, it is preferable to obtain the respiratory component and the heartbeat component from both signals in this way. The circuit configuration may be simplified.

Further, in the above-described embodiment, the heart rate / respiratory measurement device 100 digitally converts the signal obtained from the Doppler radar 10 by filtering and the filtered signal (heartbeat component signal and respiratory component signal). The configuration is such that data processing is performed to analyze heartbeat and respiration from the data. On the other hand, for example, a computer device equipped with software (program) for analyzing heartbeat and respiration in the data processing unit 113 is prepared, and a filter process or the like is performed on the data input unit of the computer device. A device or circuit board provided with an analog circuit system may be connected so that the same measurement processing as the heartbeat / respiration measurement system of the above-described embodiment may be performed. In this case, a function corresponding to the display device 200 or the recording device 300 may be built into the computer device.
Further, in the above-described embodiment, the heart rate and respiration rate for one minute are obtained as the analysis result of the heart rate and respiration, but the heart rate and respiration rate for one minute are obtained as an example, and other It is also possible to obtain the analysis results of heartbeat and respiration in the form and display or record the analysis results.

10 ... Doppler radar, 11 ... Oscillator, 12 ... Demultiplexer, 13 ... Transmitting antenna, 14 ... Receiving antenna, 15 ... 1st mixer, 17 ... π / 2 phase shifter, 18 ... 2nd mixer, 100 ... Heartbeat Respiration measuring device, 101I, 101Q ... Amplifier, 102I, 102Q ... 1st filter (bandpass filter), 103I, 103Q ... 2nd filter (bandpass filter), 103I', 103Q' ... 2nd filter (lowpass filter), 104I, 104Q ... phase corrector, 105I, 105Q ... subtractor, 111I, 111Q, 112I, 112Q ... analog / digital converter, 113 ... data processing unit, 121, 122 ... operational amplifier, 200 ... display device, 300 ... recording Device

Claims (4)

A Doppler radar that receives reflected waves of radio waves radiated to the subject,
A first filter that extracts a frequency band including a heartbeat component and a frequency band including a respiratory component from the received signal of the Doppler radar, and
A second filter that extracts a frequency band containing a respiratory component from the heartbeat component and the respiratory component extracted by the first filter and removes the frequency band containing the heartbeat component,
A subtractor that extracts the heartbeat component by subtracting the frequency component extracted by the second filter from the heartbeat component and the respiratory component extracted by the first filter.
A digital converter that digitally converts a signal containing a respiratory component extracted by the second filter and a digital converter that digitally converts a signal containing a heartbeat component extracted by the subtractor.
A data processing unit that analyzes a signal converted by the digital converter and obtains a measurement result of the heartbeat and respiration of the subject is provided.
The data processing unit detects a valley of a waveform that fluctuates in response to respiration, detects one respiration period, and further detects an inspiratory period and an exhalation period of one respiration period.
Comparing the average period of one heartbeat detected during the inspiratory period with the average period of one heartbeat detected during the expiratory period, the average period of one heartbeat detected during the inspiratory period is the expiratory period. A heartbeat / respiration measurement system that determines that the heartbeat detected in the corresponding one breathing period is an appropriate measurement result when it is shorter than the average period of one detected heartbeat. The first filter is a bandpass filter that removes low and high frequencies from the frequency band including the heartbeat component and the respiratory component.
The second filter is a low-pass filter that removes high frequencies from a frequency band containing a respiratory component, or a band-pass filter that removes low frequencies and high frequencies from a frequency band containing a respiratory component. Described heart rate / respiration measurement system. The first filter is a filter that extracts a band from about 0.1 Hz to about 3.1 Hz.
The heart rate / respiration measurement system according to claim 2 , wherein the second filter is a filter that passes a band below about 0.4 Hz. The first filter processing that obtains the reflected wave of the radio wave radiated to the subject by the Doppler radar and extracts the frequency band including the heartbeat component and the frequency band including the respiratory component from the obtained received signal, and
A second filter process for extracting a frequency band containing a respiratory component from the heartbeat component and a respiratory component extracted by the first filtering process and removing the frequency band containing the respiratory component, and a second filtering process.
A subtraction process for extracting the heartbeat component by subtracting the frequency component extracted by the second filter process from the heartbeat component and the respiratory component extracted by the first filter process.
A digital conversion process that digitally converts the signal extracted by the second filter process and digitally converts the signal extracted by the subtraction process, and a digital conversion process.
The digital conversion process by analyzing the signal converted by, saw including a data processing to obtain a measurement result of the heartbeat and respiration of the subject,
In the data processing, a valley that fluctuates according to the subject's breathing is detected to detect one breathing period, and an inspiratory period and an expiratory period of one breathing period are detected.
Comparing the average period of one heartbeat detected during the inspiratory period with the average period of one heartbeat detected during the expiratory period, the average period of one heartbeat detected during the inspiratory period is the expiratory period. A heartbeat / respiration measurement method in which when the average period of one detected heartbeat is shorter than the average period of one detected heartbeat, the heartbeat detected in the corresponding one breathing period is judged to be an appropriate measurement result.

Images