JP6970526B2 - Measuring equipment, measuring methods, and measuring programs - Google Patents

Description

The present disclosure relates to a technique for measuring the heart rate of a living body in a non-contact manner.

Techniques for measuring the heart rate of a living body in a non-contact manner are known. Heart rate refers to the number of times the heart beats within a certain period of time (for example, 1 minute). By measuring the heart rate in a non-contact manner, the burden on the living body is reduced.

Regarding the technique for measuring the heart rate in a non-contact manner, Japanese Patent Application Laid-Open No. 2010-12049 (Patent Document 1) discloses a biological signal detection device for detecting the heart rate and the respiratory rate of a driver in a non-contact manner. .. The biological signal detection device measures the driver's heart rate, respiration, etc. using a Doppler sensor.

More specifically, the Doppler sensor irradiates the driver with microwaves and receives the reflected waves of the microwaves. When the living body approaches the Doppler sensor, the frequency of the reflected wave becomes high, and when the living body moves away from the Doppler sensor, the frequency of the reflected wave becomes low. That is, when the distance between the living body and the Doppler sensor moves, a frequency difference or a phase difference (so-called Doppler shift) occurs between the irradiated microwave and its reflected wave. The Doppler sensor outputs a signal (hereinafter, also referred to as “Doppler signal”) that correlates with the phase difference. The biological signal detection device disclosed in Patent Document 1 measures the driver's heart rate, respiration, and the like based on the detected frequency component of the Doppler signal.

Japanese Unexamined Patent Publication No. 2010-120493

Various movements such as heart rate and respiration occur in the living body. Therefore, the Doppler signal detected by the Doppler sensor includes not only the signal component caused by the heartbeat of the living body (hereinafter, also referred to as “heartbeat signal”) but also the signal component caused by the breathing of the living body (hereinafter, “respiratory signal”). It is also called.). Therefore, in order to measure the heart rate from the Doppler signal, it is necessary to remove the component of the respiratory signal from the Doppler signal.

Since the waveform of the respiratory signal is close to a triangular wave, the frequency component of the respiratory signal corresponds not only to the frequency component corresponding to the respiratory rate but also to an integral multiple (typically, an odd multiple of 3 times or more) of the respiratory rate. Contains frequency components. That is, when the respiratory signal is Fourier transformed, not only the amplitude increases in the respiratory cycle, but also the amplitude increases in an integral multiple of the respiratory cycle. Hereinafter, the frequency component at an integral multiple (typically, an odd multiple of 3 times or more) of the respiratory cycle is also referred to as a “higher frequency component”.

Since the biological signal detection device disclosed in Patent Document 1 does not remove the high-order frequency component of respiration from the signal component of the Doppler signal, the heart rate cannot be accurately detected. Therefore, a technique for measuring the heart rate of a living body more accurately than before is desired.

The present disclosure has been made to solve the above-mentioned problems, and an object in a certain aspect is to provide a measuring device capable of measuring the heart rate of a living body more accurately than before. be. An object in another aspect is to provide a measuring method capable of measuring the heart rate of a living body more accurately than before. Still another aspect is to provide a measurement program capable of measuring the heart rate of a living body more accurately than before.

According to a certain aspect, the measuring device for measuring the heart rate of the living body irradiates the living body with a microwave, receives the reflected wave of the microwave, and has a frequency between the microwave and the reflected wave. A Doppler sensor for outputting a Doppler signal representing a difference or phase difference, a high-pass filter for removing low frequency components in the set cutoff band from the Doppler signal, and a reference heart rate that may include the heart rate of the living body. In order to acquire the range, acquire the heartbeat information in which the frequency band is associated with each heartbeat range of the living body, and set the frequency band associated with the reference heartbeat range in the heartbeat information as the cutoff band. And a heart rate extraction unit for determining the heart rate of the living body based on the frequency component of the heart rate signal obtained by removing the low frequency component of the set cutoff band from the Doppler signal. To prepare for.

Preferably, the setting unit newly identifies a frequency band corresponding to the changed reference heart rate range from the heart rate information based on the change of the reference heart rate range, and determines the frequency band of the high-pass filter. Reset as the cutoff band.

Preferably, the measuring device is a low-pass filter for removing a high frequency component in a frequency higher than the cutoff band from the Doppler signal, and a respiratory signal obtained by removing the high frequency component from the Doppler signal. It is provided with a respiration extraction unit for determining the respiration rate of the living body based on the frequency component. The heart rate extraction unit removes a signal component having a cycle corresponding to an integral multiple of the respiratory rate from the heart rate signal, and determines the heart rate of the living body based on the heart rate signal after the removal.

Preferably, the setting unit shifts the cutoff band set in the high-pass filter to a predetermined percentage low frequency side when the heart rate extraction unit satisfies a predetermined condition.

Preferably, when the heart rate of the living body satisfies a predetermined condition, the setting unit specifies a heart rate range next to the reference heart rate range from the heart rate ranges defined in the heart rate information. Then, the heart rate range is acquired as a new reference heart rate range.

Preferably, the heart rate determined by the heart rate extraction unit belongs to the heart rate range defined in the heart rate information and has a higher peripheral range than the reference heart rate range, or the heart rate extraction unit. If the heart rate of the living body cannot be extracted, the predetermined condition is satisfied.

According to another aspect, the measuring method for measuring the heart rate of a living body is to irradiate the living body with a microwave, receive the reflected wave of the microwave, and obtain the reflected wave between the microwave and the reflected wave. A step of outputting a Doppler signal representing a frequency difference or a phase difference, a step of removing a low frequency component of a set cutoff band from the Doppler signal, and a reference heart rate range that can include the heart rate of the living body are acquired. , The step of acquiring the heartbeat information in which the frequency band is associated with each heartbeat range of the living body and setting the frequency band associated with the reference heartbeat range in the heartbeat information as the cutoff band, and the above setting. It is provided with a step of measuring the heart rate of the living body based on the frequency component of the heart rate signal obtained by removing the low frequency component of the cutoff band from the Doppler signal.

According to another aspect, the measurement program for measuring the heart rate of a living body irradiates the living body with a microwave, receives the reflected wave of the microwave, and receives the microwave and the reflected wave. A step of outputting a Doppler signal representing a frequency difference or a phase difference between the two, a step of removing a low frequency component of a set cutoff band from the Doppler signal, and a reference heart rate range that may include the heart rate of the living body. And the step of acquiring the heartbeat information in which the frequency band is associated with each heartbeat range of the living body and setting the frequency band associated with the reference heartbeat range in the heartbeat information as the cutoff band. , The step of measuring the heart rate of the living body is executed based on the frequency component of the heart rate signal obtained by removing the low frequency component of the set cutoff band from the Doppler signal.

In a certain aspect, the heart rate of a living body can be measured more accurately than before.
The above and other objects, features, aspects and advantages of the invention will become apparent from the following detailed description of the invention as understood in connection with the accompanying drawings.

It is a figure which shows the main structure of the measuring apparatus according to 1st Embodiment. It is a figure for demonstrating the principle which determines the cut-off band of HPF. It is a figure which shows an example of the data structure of the heartbeat information. It is a figure which shows the whole structure of the measurement system according to 1st Embodiment. It is a block diagram for demonstrating the detailed structure of the control circuit according to 1st Embodiment. It is a block diagram for demonstrating the detailed structure of the analog signal processing circuit according to 1st Embodiment. It is a flowchart which shows the heart rate measurement processing in 1st Embodiment. It is a flowchart which shows the measurement process of the respiratory rate in 1st Embodiment. It is a flowchart which shows the body movement detection processing in 1st Embodiment. It is a flowchart which shows the heart rate measurement processing in 2nd Embodiment. It is a flowchart which shows the heart rate measurement processing in 3rd Embodiment.

Hereinafter, the present embodiment will be described with reference to the drawings. In the following description, the same parts and components are designated by the same reference numerals. Their names and functions are the same. Therefore, the detailed description of these will not be repeated. In addition, each modification described below may be selectively combined as appropriate.

<First Embodiment>
[Overview of heart rate measurement processing]
A method of measuring the heart rate of a living body by the measuring device 100 will be described with reference to FIGS. 1 to 3. FIG. 1 is a diagram showing a main configuration of a measuring device 100 for measuring a heart rate of a living body.

As shown in FIG. 1, the measuring device 100 includes a Doppler sensor 40, a high-pass filter (HPF) 64, a fundamental wave detection unit 66, a setting unit 67, and a heart rate extraction unit 68.

The Doppler sensor 40 irradiates the living body P to be measured with microwaves, and receives the reflected waves of the microwaves from the living body P. The living body P is, for example, an animal such as a person. When the living body P approaches the Doppler sensor 40, the frequency of the reflected wave becomes high, and when the living body P moves away from the Doppler sensor, the frequency of the reflected wave becomes low. That is, the phase of the Doppler signal changes depending on the respiration and heartbeat of the living body P. Therefore, a phase difference (so-called Doppler shift) occurs between the irradiated microwave and its reflected wave. The Doppler sensor 40 outputs a Doppler signal that correlates with the phase difference. The Doppler signal is output to HPF64.

The HPF64 removes low frequency components in the set cutoff band from the Doppler signal. The cutoff band of the HPF 64 is set by the setting unit 67. As an example, the upper limit value of the cutoff band is set by the setting unit 67, and the signal component of the frequency band equal to or lower than the upper limit value is removed from the Doppler signal.

FIG. 2 is a diagram for explaining the principle of determining the cutoff band of HPF64. The principle will be described with reference to FIG.

FIG. 2 shows graphs G1 to G3. Graphs G1 to G3 show spectra of Doppler signals. That is, the graphs G1 to G3 show the signal strength of the Doppler signal for each frequency band.

More specifically, the horizontal axis of the graphs G1 to G3 represents the frequency. The unit on the horizontal axis is expressed in Hz. Multiplying the frequency by "60" gives the frequency of the living body per minute, and the frequency represents the heart rate or the respiratory rate of the living body. Since the unit of heart rate and respiratory rate is represented by "bpm (Beats Per Minute)", the horizontal axis of the graphs G1 to G3 may be represented by "bpm". The vertical axis of the graphs G1 to G3 indicates the signal strength.

As shown in graphs G1 to G3, the Doppler signal may include heartbeat components A1 to A3 caused by the heartbeat of the living body and respiratory components B1 to B3 and B5 caused by the respiration of the living body. The waveform of the respiration signal is close to that of a triangular wave, and the spectrum of the triangular wave contains not only a signal component corresponding to the frequency of the triangular wave but also a high-order frequency component corresponding to an odd multiple of the period of the triangular wave. Therefore, the frequency component of the Doppler signal may include not only the respiratory component B1 corresponding to the actual respiratory rate of the living body but also the frequency component corresponding to an integral multiple of the respiratory rate. In particular, the signal intensity of the respiratory component B3, which corresponds to three times the respiratory rate, becomes stronger. Since the amplitude of the respiratory signal is about 10 times or more the amplitude of the heart rate signal, the respiratory component B3 becomes a large noise in extracting the heart rate. Therefore, the measuring device 100 according to the present embodiment extracts the heart rate of the living body after removing not only the respiratory component B1 but also the respiratory component B3 of the higher frequency component.

As an example, the setting unit 67 selects one of the cutoff bands HR1 to HR3 prepared in advance, and sets the selected cutoff band to HPF64.

When the cutoff band HR1 is set to HPF64, the signal component of 0.8 Hz or less (48 bpm or less) is removed from the Doppler signal. In this case, the respiratory components B1 and B2 are removed from the Doppler signal, but the respiratory components B3 are not removed from the Doppler signal.

When the cutoff band HR2 is set to HPF64, the signal component of 1.1 Hz or less (66 bpm or less) is removed from the Doppler signal. In this case, the respiratory components B1 to B3 are removed from the Doppler signal.

When the cutoff band HR3 is set to HPF64, the signal component of 1.4 Hz or less (84 bpm or less) is removed from the Doppler signal. In this case, not only the respiratory components B1 to B3 are removed, but also the heart rate component A1 is removed.

Such a suitable cutoff band can be determined by the heart rate of the living body. Therefore, the correspondence between the heart rate of the living body and the cutoff band of HPF64 can be predetermined as the heart rate information 122 by an experiment or the like. The setting unit 67 determines the cutoff band of the HPF 64 based on the heart rate information 122.

FIG. 3 is a diagram showing an example of the data structure of the heart rate information 122. As shown in FIG. 3, in the heart rate information 122, the cutoff band of HPF 64 is defined for each heart rate range representing the range of the heart rate. Preferably, the cutoff band of the low-pass filter described later is further defined in the heart rate information 122. The cutoff band of the low-pass filter will be described later.

The user selects a heart rate range including his / her heart rate from the heart rate ranges defined in the heart rate information 122, and sets the heart rate range as a reference heart rate range in the measuring device 100 in advance. Upon receiving the heart rate measurement instruction, the setting unit 67 identifies the cutoff band associated with the reference heart rate range from the cutoff bands defined in the heart rate information 122, and sets the cutoff band. Set to HPF64. The HPF 64 removes a low frequency component in the set cutoff band, and outputs the heartbeat signal after the removal to the fundamental wave detection unit 66.

The heart rate extraction unit 68 extracts the heart rate of the living body based on the frequency component of the heart rate signal obtained from the HPF64. More specifically, the fundamental wave detection unit 66 executes a fast Fourier transform (FFT) on the heartbeat signal, and obtains frequency distribution data (that is, spectral data) representing the signal strength for each frequency band. create. The fundamental wave detection unit 66 detects the frequency component having the highest signal intensity (peak) from the frequency distribution data as the fundamental wave data. The fundamental wave detection unit 66 may detect fundamental wave data by using an autocorrelation function or a wavelet transform. The heart rate extraction unit 68 calculates the heart rate of the living body by multiplying the fundamental wave data by 60.

As described above, the measuring device 100 removes not only the respiratory component B1 but also the respiratory component B3, which is a high-order frequency component, from the Doppler signal in the HPF 64, and extracts the heart rate of the living body based on the heart rate signal after the removal. .. By removing the respiratory component B3, which is a high-order frequency component, the heart rate of the living body is measured more accurately.

Such a non-contact heart rate measuring device 100 is used in various situations. As an example, the measuring device 100 is used to measure the driver's heart rate when driving a car. Alternatively, the measuring device 100 is used to measure the heart rate of a patient in a nursing facility or a medical facility.

Preferably, the setting unit 67 newly identifies a frequency band corresponding to the changed reference heart rate range from the heart rate information 122 based on the change of the reference heart rate range, and sets the frequency band as the cutoff band of HPF 64. Reset as. That is, the cutoff band set in the HPF 64 is switched in conjunction with the setting of the reference heart rate range 124.

In the above description, an example in which the reference heart rate range is preset by the user has been described, but the reference heart rate range may be automatically set as described in the "third embodiment".

Further, in the heart rate information 122 of FIG. 3, an example in which the heart rate range is divided into three and defined is described, but the heart rate range may be divided into two and defined. It may be divided into two or more.

[Measurement system 1000]
FIG. 4 is a diagram showing an overall configuration of the measurement system 1000 according to the first embodiment. With reference to FIG. 4, the measurement system 1000 includes a measurement device 100 for monitoring a subject and a terminal device 200. The terminal device 200 is a terminal for receiving the measurement result by the measuring device 100, and is, for example, a smartphone. However, the terminal device 200 may be another device such as a foldable mobile phone, a tablet terminal device, or a PC (personal computer).

The network 55 for connecting the measuring device 100 and the terminal device 200 to each other includes various networks such as the Internet. The network 55 is not limited to this, and a wired communication method may be adopted, or another wireless communication method such as a wireless LAN (local area network) may be adopted.

The measuring device 100 includes a Doppler sensor 40, a control circuit 152, a memory 154, a speaker 156, and a communication interface 158 as main components. The measuring device 100 may include a display for displaying various information and an input device such as a button for receiving various inputs from the user.

The control circuit 152 typically includes a microprocessor including a CPU and the like, an analog signal processing circuit for processing an analog signal from the Doppler sensor 40, and an AD (Analog to Digital) converter. The detailed configuration of the control circuit 152 will be described later. The microprocessor reads and executes the program stored in the memory 154, and functions as a control unit that controls the operation of each unit of the measuring device 100. For example, the microprocessor realizes the processing of the control circuit 152 described later by executing the program.

The memory 154 is realized by a RAM (Random Access Memory), a ROM (Read-Only Memory), or the like. The memory 154 stores a program executed by the microprocessor, data used by the microprocessor, and the like.

The speaker 156 converts the voice signal given from the microprocessor into voice and outputs it to the outside of the measuring device 100. The communication interface 158 encodes the communication data from the microprocessor, converts it into a communication signal, and transmits the communication signal to the terminal device 200. Further, the received signal is decoded from the terminal device 200, converted into communication data, and output to the microprocessor. The communication method may be a wireless communication method using a wireless LAN or the like, or a wired communication method using USB (Universal Serial Bus) or the like.

The Doppler sensor 40 irradiates the living body P with microwaves, and outputs a signal reflecting the movement of the body of the living body P to the control circuit 152 from the reflected microwaves. Further, the Doppler sensor 40 generates an I-channel signal and a Q-channel signal orthogonal to each other from the input reflected signal.

Specifically, the Doppler sensor 40 includes an oscillation circuit 21, amplifiers 22A and 22B, a transmitting antenna 25, a receiving antenna 30, mixers 32I and 32Q, LPF33I and 33Q, and a 90-degree phase shifter 38. include. The transmitting antenna 25 and the receiving antenna 30 are composed of a planar antenna. The transmitting antenna 25 and the receiving antenna 30 may be composed of a waveguide antenna or a dielectric antenna.

The microwave sine wave signal output from the oscillation circuit 21 is amplified by the amplifier 22A and irradiated from the transmitting antenna 25. The microwave Mt irradiated to the space is reflected by the body surface (for example, the chest) of the living body P, which is an object. In the reflected wave Mr of the irradiated microwave, a Doppler shift corresponding to the body movement (body movement) of the living body P and the respiratory movement and the heartbeat movement occurs. Therefore, the signal (reflected signal) of the reflected wave Mr input to the receiving antenna 30 becomes a signal corresponding to the body movement, the respiratory movement, and the heartbeat movement of the living body P.

The reflected signal received by the receiving antenna 30 is amplified by the amplifier 22B. The amplified signal Dr is input to the mixer 32I on the I channel side and the mixer 32Q on the Q channel side. Here, the signal Dr input to the I channel side is referred to as "Dri" for convenience, and the signal Dr input to the Q channel side is referred to as "Drq" for convenience.

The signal Dt amplified by the amplifier 22A is input to the mixer 32I on the I channel side and the mixer 32Q via the 90-degree phase shifter 38. Here, the signal Dt input to the I channel side is referred to as "Dti" for convenience, and the signal Dt input to the Q channel side is referred to as "Dtq" for convenience. In the present embodiment, a configuration in which the phase of the signal Dtq with respect to the signal Dti is shifted by 90 degrees by using the 90-degree phase shifter 38 will be described, but the configuration is not limited to this. For example, by using the 90-degree phase shifter 38, the phase of the signal Drq with respect to the signal Dri may be shifted by 90 degrees.

The frequency-converted (down-converted) signal by the mixer 32I is input to the LPF33I. The LPF33I outputs a signal obtained by removing a relatively high frequency component from the signal to the analog signal processing circuit 41 as a baseband signal Dbi on the I channel side. Further, the signal frequency-converted by the mixer 32Q is input to the LPF33Q. The LPF33Q outputs a signal obtained by removing a relatively high frequency component from the signal to the control circuit 152 as a baseband signal Dbq on the Q channel side. The baseband signals Dbi and Dbq are output as Doppler signals that have undergone Doppler shift due to the body movement of the living body P, respectively.

The speed and amplitude of the reflected signal input to the receiving antenna 30 changes with time. Therefore, although the I-channel side signal and the Q-channel side signal are instantaneously 90 degrees out of phase, the phase advance of the baseband signal Dbq with respect to the baseband signal Dbi depends on the speed and direction of the signal. The one is not constant and always fluctuates with time.

[Control circuit 152]
FIG. 5 is a block diagram for explaining a detailed configuration of the control circuit 152 according to the first embodiment. With reference to FIG. 5, the control circuit 152 includes an analog signal processing circuit 41, an AD converter 43, and a microprocessor 45. Typically, the microprocessor 45 is a digital signal processor (DSP) specialized in digital signal processing.

The analog signal processing circuit 41 removes unnecessary frequency band components from the signal input from the Doppler sensor 40 and outputs the signal to the AD converter 43. Specifically, the analog signal processing circuit 41 outputs the I-channel analog signal Shi and the Q-channel analog signal Shq in the heartbeat component band (0.7 Hz to 20 Hz), and outputs the body movement component band (0.1 Hz). ~ 40Hz) I-channel analog signal Sti and Q-channel analog signal Stq are output. The band of the body movement component also includes the band of the respiratory component.

The AD converter 43 performs 16-bit (or 12-bit) AD conversion of the input signal. Specifically, the AD converter 43 receives the inputs of the analog signals Shi, Shq, Sti, and Stq, and converts the analog signals Shi, Shq, Sti, and Stq into digital signals at a predetermined sampling rate (for example, 10 msec). And output to the microprocessor 45. The digital signals Shi, Shq, Ti, and Stq are appropriately offset-adjusted as ± signals according to the voltage amplitude.

The microprocessor 45 executes various processes using each digital signal Shi, Shq, Ti, Stq. Specifically, the microprocessor 45 includes a body motion detection unit 50, an output control unit 52, a heart rate calculation unit 60, and a respiration calculation unit 70 as main functional configurations.

The heart rate calculation unit 60 receives the inputs of the digital signals Shi and Shq and executes various processes. Specifically, the heart rate calculation unit 60 includes a high-pass filter (HPF) 64I on the I channel side, HPF64Q on the Q channel side, LPF65I on the I channel side, LPF65Q on the Q channel side, and a fundamental wave on the I channel side. It includes a detection unit 66I, a fundamental wave detection unit 66Q on the Q channel side, a setting unit 67, and a heartbeat extraction unit 68.

The HPF64I and 64Q generate digital signals Hai and Haq by removing the low frequency components (particularly, the band of the respiratory component) of the digital signals Shi and Shq, respectively. Hereinafter, at least one of HPF64I and 64Q is also referred to as HPF64.

The cutoff band of the HPF 64 is set by the setting unit 67 as described above. More specifically, the setting unit 67 identifies from among the heart rate ranges defined in the heart rate information 122, those that match or substantially match the reference heart rate range 124 to which the heart rate of the measurement target belongs, and specify the specific heart rate. The frequency band associated with the assigned heart rate range is set as the cutoff band of HPF64. The reference heart rate range 124 may be preset by the user or may be set automatically.

The LPF65I and 65Q generate digital signals Hbi and Hbq by removing high frequency components of the digital signals Hai and Haq, respectively. Hereinafter, at least one of LPF65I and 65Q is also referred to as LPF65. The cutoff band of the LPF 65 is set by the setting unit 67. More specifically, the setting unit 67 identifies a heart rate range defined in the heart rate information 122 that matches or substantially matches the reference heart rate range 124, and is associated with the specified heart rate range. The frequency band is set as the cutoff band of LPF65. The LPF65I outputs the digital signal Hbi to the fundamental wave detection unit 66I, and the LPF65Q outputs the digital signal Hbq to the fundamental wave detection unit 66Q.

The fundamental wave detection units 66I and 66Q calculate the heart rate using the digital signals Hbi and Hbq, respectively. Specifically, the fundamental wave detection unit 66I performs a fast Fourier transform (FFT) on the digital signal Hbi accumulated for a predetermined time (for example, 30 seconds), decomposes it into individual signal components, and then decomposes each component. Is performed on the frequency spectrum to create frequency distribution data. The fundamental wave detection unit 66I detects the frequency component having the highest intensity (peak) among the frequency distribution data as the fundamental wave data. The fundamental wave detection units 66I and 66Q may detect fundamental wave data by using an autocorrelation function or a wavelet transform.

The fundamental wave detection unit 66I calculates the heart rate Hi, which is the number of heartbeats per unit time (that is, one minute), by multiplying the fundamental wave data by 60. Similarly, the fundamental wave detection unit 66Q calculates the heart rate Hq using the digital signal Hbq.

The heart rate extraction unit 68 averages the heart rate Hi and the heart rate Hq to calculate the heart rate Hn. The heart rate extraction unit 68 may integrate the digital signals Hbi and Hbq and appropriately set a threshold value to remove a signal having a low noise level intensity or a signal having poor periodicity.

The respiration calculation unit 70 receives the inputs of the digital signals Sti and Stq and executes various processes. Specifically, the respiration calculation unit 70 includes the LPF71I on the I channel side, the LPF71Q on the Q channel side, the fundamental wave detection unit 72I on the I channel side, the fundamental wave detection unit 72Q on the Q channel side, and the respiration extraction unit. 73 and is included.

The LPF71I and 71Q generate digital signals Bai and Baq by removing high frequency components of the digital signals Sti and Stq, respectively. The LPF71I outputs the digital signal Bai to the fundamental wave detection unit 72I, and the LPF71Q outputs the digital signal Baq to the fundamental wave detection unit 72Q. Typically, the LPF71I, 71Q removes frequency components above 0.75 Hz (ie, corresponding to 45 bpm).

The fundamental wave detection units 72I and 72Q calculate the respiratory rate using the digital signals Bai and Baq, respectively. The fundamental wave detection unit 72I calculates the respiratory rate by the same calculation method as the calculation method by the fundamental wave detection unit 66I. Specifically, the fundamental wave detection unit 72I creates frequency distribution data by performing a high-speed Fourier transform on the digital signal Bai accumulated for a predetermined time. The fundamental wave detection unit 72I detects the frequency component having the highest intensity among the frequency distribution data as the fundamental wave data. The fundamental wave detection unit 72I calculates the respiratory rate Bi, which is the number of respirations per unit time (that is, one minute), by multiplying the fundamental wave data by 60. Similarly, the fundamental wave detection unit 72Q calculates the respiratory rate Bq using the digital signal Baq.

The respiratory extraction unit 73 averages the respiratory rate Bi and the respiratory rate Bq to calculate the respiratory rate Bn. The breathing extraction unit 73 may integrate the digital signals Bai and Baq and appropriately set a threshold value to remove a signal having a low noise level intensity or a signal having poor periodicity.

The body motion detection unit 50 detects the body motion of the living body P based on a predetermined threshold value and a reflected signal (specifically, each digital signal Sti, Stq). The threshold value is a digital value when the amplitude values (voltage 0V to 3.3V) of the analog signals Sti and Stq are AD-converted.

Specifically, the body motion detection unit 50 calculates the magnitude (absolute value) of the amplitude of each of the digital signals Sti and Stq at regular time intervals (for example, 0.2 seconds). For example, when the sampling frequency is 100 Hz, the body motion detection unit 50 samples the digital signals for each of the digital signals Sti and Stq every 10 milliseconds, and averages the absolute values of 20 sampling data. Calculate the value (average absolute value). The body movement detection unit 50 calculates the calculated average absolute value at regular time intervals, and sequentially stores the calculated result in association with the time.

The body movement detection unit 50 detects body movements such as getting up of a living body, for example. More specifically, the body motion detection unit 50 raises the living body P from the bedding when both the average absolute value for the digital signal Sti and the average absolute value for the digital signal Stq are equal to or higher than a predetermined threshold value. Judged as Further, the body movement detection unit 50 may determine that the living body P has risen from the bedding when the average absolute value for at least one of the digital signals Sti and Stq becomes a predetermined threshold value or more. Alternatively, the body movement detection unit 50 may calculate the synthetic signals of the digital signals Sti and Stq and determine that the living body P has risen from the bedding when the average absolute value for the synthetic components becomes equal to or higher than a predetermined threshold value. good.

The output control unit 52 outputs a body movement detection result by the body movement detection unit 50, a heart rate measurement result by the heart rate calculation unit 60, a respiration rate measurement result by the respiration calculation unit 70, and the like. The output mode of these measurement results is arbitrary. In a certain aspect, the output control unit 52 outputs warning information when it receives a determination result of a body movement abnormality, a heartbeat abnormality, or a respiratory abnormality. The output control unit 52 may output the warning information by voice via the speaker 156, or may display the warning information on the display. Further, the output control unit 52 may transmit warning information to the terminal device 200 via the communication interface 158. In another aspect, these measurement results are, for example, digitized according to a predetermined format and then transmitted to the terminal device 200 via the communication interface 158 (see FIG. 4). The terminal device 200 displays the measurement result received from the measuring device 100.

[Analog signal processing circuit 41]
FIG. 6 is a block diagram for explaining a detailed configuration of the analog signal processing circuit 41 according to the first embodiment.

With reference to FIG. 6, the analog signal processing circuit 41 receives the I-channel side baseband signal Dbi output from the Doppler sensor 40 and the Q-channel side baseband signal Dbq output from the Doppler sensor 40 as inputs. receive. The baseband signal Dbi is distributed to the analog signals Dbia and Dbib. The baseband signal Dbq is distributed to the analog signals Dbqa and Dbqb.

The analog signal processing circuit 41 includes signal processing circuits 149A to 149D. The analog signal Dbia is output to the signal processing circuit 149A for heart rate measurement. The signal processing circuit 149A includes HPF143A, LFP144A, and an amplifier 145A.

HPF143A removes the low frequency component of the analog signal Dbia. As an example, HPF143A removes signal components below 0.8 Hz. The removed signal is output to the LFP144A.

The LFP144A removes the high frequency component of the analog signal Dbia output from the HPF143A. As an example, LFP144A removes signal components above 20 Hz. The removed signal is output to the amplifier 145A.

The amplifier 145A amplifies the analog signal Dbia output from the LFP 144A by a predetermined time (for example, 400 times) to generate the analog signal Shi. The analog signal Shi is output to the AD converter 43 (see FIG. 5) described above.

The analog signal Dbib is output to the signal processing circuit 149B for respiration measurement. The signal processing circuit 149B includes HPF143B, LFP144B, and an amplifier 145B.

HPF143B removes the low frequency component of the analog signal Dbib. As an example, HPF143B removes signal components below 0.1 Hz. The removed signal is output to LFP144B.

The LFP144B removes the high frequency component of the analog signal Dbib output from the HPF143B. As an example, LFP144B removes signal components above 20 Hz. The removed signal is output to the amplifier 145B.

The amplifier 145B amplifies the analog signal Dbib output from the LFP144B by a predetermined time (for example, 100 times) to generate the analog signal Sti. The analog signal Sti is output to the AD converter 43 (see FIG. 5) described above.

Since the amplitude of the heartbeat signal is about 1/10 or less of the amplitude of the respiration signal, the amplification factor of the heartbeat measurement amplifier 145A is larger than the amplification factor of the respiration measurement amplifier 145B. Amplitudes 145A and 145B are designed. As an example, the amplification factor of the amplifier 145A is 400 times, and the amplification factor of the amplifier 145B is 100 times.

The analog signal Dbqa is output to the signal processing circuit 149C for heart rate measurement. The signal processing circuit 149C includes an HPF143C, an LFP144C, and an amplifier 145C.

HPF143C removes the low frequency component of the analog signal Dbqa. As an example, HPF143C removes signal components below 0.8 Hz. The removed signal is output to the LFP144C.

The LFP144C removes the high frequency component of the analog signal Dbqa output from the HPF143C. As an example, LFP144C removes signal components above 20 Hz. The removed signal is output to the amplifier 145C.

The amplifier 145C amplifies the analog signal Dbqa output from the LFP 144C by a predetermined time (for example, 400 times) to generate the analog signal Shq. The analog signal Shq is output to the AD converter 43 (see FIG. 5) described above.

The analog signal Dbqb is output to the signal processing circuit 149D for respiration measurement. The signal processing circuit 149D includes HPF143D, LFP144D, and an amplifier 145D.

HPF143D removes the low frequency component of the analog signal Dbqb. As an example, HPF143D removes signal components below 0.1 Hz. The removed signal is output to the LFP144D.

The LFP144D removes the high frequency component of the analog signal Dbqb output from the HPF143D. As an example, LFP144D removes signal components above 20 Hz. The removed signal is output to the amplifier 145D.

The amplifier 145D amplifies the analog signal Dbqb output from the LFP 144D by a predetermined time (for example, 100 times) to generate the analog signal Stq. The analog signal Stq is output to the AD converter 43 (see FIG. 5) described above.

Since the amplitude of the heartbeat signal is about 1/10 or less of the amplitude of the respiration signal, the amplification factor of the heartbeat measurement amplifier 145C is larger than the amplification factor of the respiration measurement amplifier 145D. Amplitudes 145C and 145D are designed. As an example, the amplification factor of the amplifier 145C is 400 times, and the amplification factor of the amplifier 145D is 100 times.

HPF143A to 143D and LFP144A to 144D are, for example, active filters using operational amplifiers. Alternatively, the HPFs 143A to 143D may be passive elements using the coil L, the capacitor C, and the resistor R.

As described above, by independently performing band limitation and amplification for amplitude measurement and respiration measurement, a high-quality analog signal having a high SN (Signal Noise) ratio is extracted in the heartbeat range and the respiration range. The LFPs 144A to 144D also function as an antialiasing filter for the AD converter 43 described above.

[Control structure of measuring device 100]
The control structure of the measuring device 100 will be described with reference to FIGS. 7 to 9. FIG. 7 is a flowchart showing the heart rate measurement process. FIG. 8 is a flowchart showing a respiratory rate measurement process. FIG. 9 is a flowchart showing the body movement detection process. The processes of FIGS. 7 to 9 are realized by executing the program by the microprocessor 45 of the measuring device 100. In other aspects, some or all of the processing may be performed by circuit elements or other hardware.

Below, the flow of the heart rate measurement process, the flow of the respiratory rate measurement process, and the flow of the body movement detection process will be described in order.

(Heart rate measurement processing)
First, the flow of the heart rate measurement process will be described with reference to FIG. 7.

In step S110, the microprocessor 45 irradiates microwaves via the Doppler sensor 40. After that, the microprocessor 45 receives the reflected wave of the irradiated microwave and generates a Doppler signal on the I channel side and a Doppler signal on the Q channel side from the reflected wave signal.

In step S120, the microprocessor 45 acquires a frequency band (that is, a reference heart rate range) including the frequency of the living body to be measured. In the present embodiment, it is assumed that the reference heart rate range is set in advance. In a certain aspect, a lower limit value is set by the user, and a range above the lower limit value is set as a reference heart rate range. In another aspect, the lower limit value and the upper limit value are set by the user, and the range of the lower limit value or more and less than the upper limit value is set as the reference heart rate range. In another aspect, the user sets one of the heart rate ranges defined in the heart rate information 122 (see FIG. 3) as the reference heart rate range.

In step S130, the microprocessor 45 refers to the heart rate information 122, acquires a cutoff band for the HPF associated with the reference heart rate range, and sets the cutoff band to the HPF64I, 64Q (see FIG. 5). Set. Similarly, the microprocessor 45 refers to the heart rate information 122, acquires a cutoff band for the LPF associated with the reference heart rate range, and sets the cutoff band to LPF65I, 65Q (see FIG. 5). do.

In step S140, the microprocessor 45 removes the signal component included in the cutoff band set in the HPF64I from the Doppler signal on the I channel side. As an example, when the heart rate range "45 bpm to 260 bpm" shown in FIG. 3 is set as the reference heart rate range, HPF64I removes the signal component of "0.7 to 0.8 Hz or less". As another example, when the heart rate range "63 bpm to 260 bpm" shown in FIG. 3 is set as the reference heart rate range, HPF64I removes the signal component of "1.0 to 1.1 Hz or less". As another example, when the heart rate range "81 bpm to 260 bpm" shown in FIG. 3 is set as the reference heart rate range, HPF64I removes the signal component of "1.3 to 1.4 Hz or less". Similar to the HPF64I, the microprocessor 45 removes the signal component included in the cutoff band set in the HPF64Q from the Doppler signal on the Q channel side.

In step S150, the microprocessor 45 removes the signal component included in the cutoff band set in the LPF65I from the Doppler signal on the I channel side. As an example, when the heart rate range "45 bpm to 260 bpm" shown in FIG. 3 is set as the reference heart rate range, the LPF65I removes the signal component of "7 Hz or higher". As another example, when the heart rate range "63 bpm to 260 bpm" shown in FIG. 3 is set as the reference heart rate range, the LPF65I removes the signal component of "10 Hz or higher". As another example, when the heart rate range "81 bpm to 260 bpm" shown in FIG. 3 is set as the reference heart rate range, the LPF65I removes the signal component of "20 Hz or higher". Similar to the LPF65I, the microprocessor 45 removes the signal component included in the cutoff band set in the LPF65Q from the Doppler signal on the Q channel side.

In step S151, the microprocessor 45 detects the periodicity of the Doppler signal on the I channel side that has passed through the HPF64I and LPF65I. Typically, the microprocessor 45 generates frequency distribution data by performing a fast Fourier transform on the Doppler signal on the I channel side that has passed through HPF64I and LPF65I, and the frequency component having a high signal intensity (peak) is generated from the frequency distribution data. Is detected as fundamental wave data. Similarly, frequency distribution data is generated by fast Fourier transform of the Doppler signal on the Q channel side that has passed through HPF64Q and LPF65Q, and the frequency component with high signal intensity (peak) is detected as fundamental wave data from the frequency distribution data. .. The microprocessor 45 may detect fundamental wave data by using an autocorrelation function or a wavelet transform.

In step S160, the microprocessor 45 calculates the heart rate per unit time (that is, one minute) by multiplying the fundamental wave data on the I channel side by 60. Similarly, the microprocessor 45 calculates the heart rate per unit time (that is, one minute) by multiplying the fundamental wave data on the Q channel side by 60. The microprocessor 45 averages the heart rate on the I-channel side and the heart rate on the Q-channel side to calculate the heart rate as a measurement result.

If the predetermined conditions are satisfied in the process of calculating the heart rate, the microprocessor 45 may output a measurement error as if the heart rate could not be measured. As an example, when the heart rate cycle falls below a predetermined threshold value, the predetermined condition is satisfied. In the case of, the process shown in FIG. 7 may be terminated or may be executed again.

In step S170, the microprocessor 45 outputs the measurement result of the heart rate in step S160. The output mode of the measurement result is arbitrary. In a certain aspect, the microprocessor 45 determines that the heart rate is abnormal when the heart rate is equal to or less than a predetermined lower limit value or is greater than or equal to a predetermined upper limit value, and outputs warning information. The warning information may be output by voice via the speaker 156 or may be output via the display. Further, the microprocessor 45 may transmit warning information to the terminal device 200 via the communication interface 158.

(Respiratory rate measurement processing)
Next, with reference to FIG. 8, the flow of the respiratory rate measurement process will be described.

In step S210, the microprocessor 45 irradiates microwaves via the Doppler sensor 40. After that, the microprocessor 45 receives the reflected wave of the irradiated microwave and generates a Doppler signal on the I channel side and a Doppler signal on the Q channel side from the reflected wave signal.

In step S220, the microprocessor 45 uses the LPF71I for respiration measurement (see FIG. 5) to remove a signal component of a predetermined frequency from the Doppler signal on the I channel side. Similarly, the microprocessor 45 uses the LPF71Q for respiration measurement (see FIG. 5) to remove a signal component of a predetermined frequency from the Doppler signal on the Q channel side. As an example, the cutoff band of LPF71I, 71Q is 0.75 Hz or more.

In step S221, the microprocessor 45 detects the periodicity of the Doppler signal on the I channel side that has passed through the LPF71I. Typically, the microprocessor 45 generates frequency distribution data by performing a high-speed Fourier transform on the Doppler signal on the I channel side that has passed through the LPF71I, and basically uses the frequency component having a high signal strength (peak) from the frequency distribution data. Detect as wave data. Similarly, the microprocessor 45 generates frequency distribution data by performing a high-speed Fourier transform on the Doppler signal on the Q channel side that has passed through the LPF71Q, and from the frequency distribution data, the frequency component having a high signal intensity (peak) is the fundamental wave data. Detect as. The microprocessor 45 may detect fundamental wave data by using an autocorrelation function or a wavelet transform.

In step S230, the microprocessor 45 calculates the respiratory rate per unit time (that is, 1 minute) by multiplying the fundamental wave data on the I channel side by 60. Similarly, the microprocessor 45 calculates the respiratory rate per unit time (that is, one minute) by multiplying the fundamental wave data on the Q channel side by 60. The microprocessor 45 averages the respiratory rate on the I-channel side and the respiratory rate on the Q-channel side to calculate the respiratory rate as a measurement result. The microprocessor 45 may remove a signal having a low noise level intensity or a signal having poor periodicity by appropriately setting a threshold value.

In step S240, the microprocessor 45 outputs the measurement result of the respiratory rate in step S230. The output mode of the measurement result is arbitrary. In a certain aspect, the microprocessor 45 determines that the respiratory rate is equal to or higher than the predetermined lower limit value or is greater than or equal to the predetermined upper limit value, and outputs warning information. The warning information may be output by voice via the speaker 156 or may be output via the display. Further, the microprocessor 45 may transmit warning information to the terminal device 200 via the communication interface 158.

(Body movement detection process)
Next, the flow of the body movement detection process will be described with reference to FIG.

In step S310, the microprocessor 45 irradiates microwaves via the Doppler sensor 40. After that, the microprocessor 45 receives the reflected wave of the irradiated microwave and generates a Doppler signal on the I channel side and a Doppler signal on the Q channel side from the reflected wave signal.

In step S320, the microprocessor 45 detects the body movement of the living body P based on the Doppler signal on the I channel side, the Doppler signal on the Q channel side, and a predetermined threshold value. As an example, the microprocessor 45 detects the rising of a living body and the like. Since the method for detecting the rise of a living body is as described above, the explanation thereof will not be repeated.

In step S330, the microprocessor 45 outputs the detection result of the body movement in step S320. The output mode of the detection result is arbitrary. In a certain aspect, when the measuring device 100 is used as a patient monitoring device, the microprocessor 45 outputs that the patient has risen up. This may be output via the speaker 156 or may be output via the display. Further, the microprocessor 45 may transmit warning information to the terminal device 200 via the communication interface 158.

[Summary of the first embodiment]
As described above, the measuring device 100 according to the present embodiment acquires the reference heart rate range that can include the heart rate of the living body to be measured, and sets the frequency band including the signal component caused by the respiration of the living body to the heart rate of the living body. The heart rate information 122 (see FIG. 3) associated with each range is acquired. The measuring device 100 sets the frequency band associated with the reference heart rate range in the heart rate information 122 as the cutoff band in the HPF 64 for heart rate measurement. In this way, by appropriately setting the cutoff band of HPF64 according to the reference heart rate range, it is possible to remove not only the frequency component corresponding to the respiratory rate of the living body but also the higher frequency component of the respiratory rate. .. By extracting the heart rate after removing the high-order frequency component, the measuring device 100 can measure the heart rate of the living body more accurately.

<Second embodiment>
[Overview]
The measuring device 100 according to the first embodiment sets a cutoff band in the HPF 64 (see FIG. 1) so as to remove the higher frequency component of respiration. As a result, the measuring device 100 removed the high-order frequency component of respiration (mainly the third-order high frequency component) from the Doppler signal. However, if the cutoff band set in HPF64 is close to the third-order frequency component of respiration, it may not be possible to completely remove the third-order frequency component. Therefore, the measuring device 100 according to the second embodiment removes the tertiary frequency component of respiration from the frequency distribution data obtained by frequency-decomposing the Doppler signal, and then based on the frequency distribution data, the heartbeat of the living body. Extract the number. As a result, the measuring device 100 is not affected by the tertiary frequency component of respiration, and the heart rate of the living body can be measured more accurately.

Since the other points such as the hardware configuration of the measuring device 100 according to the second embodiment are the same as those of the measuring device 100 according to the first embodiment, the description thereof will not be repeated below.

[Control structure of measuring device 100]
The control structure of the measuring device 100 will be described with reference to FIG. FIG. 10 is a flowchart showing a heart rate measurement process according to the second embodiment. The process of FIG. 10 is realized by executing a program by the microprocessor 45 of the measuring device 100. In other aspects, some or all of the processing may be performed by circuit elements or other hardware.

Since the processes other than steps S152 and S160A are as described in FIG. 7, the description thereof will not be repeated.

In step S152, the microprocessor 45 acquires the respiratory rate of the living body to be measured. Since the method of measuring the respiratory rate is as described in FIG. 8, the description will not be repeated.

In step S160A, the microprocessor 45 performs a fast Fourier transform on the Doppler signal on the I channel side that has passed through the HPF64 and LPF65. After decomposing into individual signal components, the microprocessor 45 performs a process of expressing each component on a frequency spectrum to create frequency distribution data. The microprocessor 45 measures the heart rate of a living body based on the created frequency distribution data. At this time, the microprocessor 45 changes the heart rate measurement process according to the set reference heart rate range.

As an example, it is assumed that the heart rate range "63 bpm to 260 bpm" shown in FIG. 3 is set as the reference heart rate range. In this case, the microprocessor 45 removes a high-order high-frequency component having a period corresponding to an integral multiple of the respiratory rate from the frequency distribution data (heartbeat signal), and determines the heart rate of the living body based on the frequency distribution data after the removal. Extract. Preferably, higher frequency components with a period corresponding to three times the respiratory rate are removed from the frequency distribution data. After that, the microprocessor 45 detects the frequency component having the highest signal intensity (peak) from the frequency distribution data as the fundamental wave data. The microprocessor 45 calculates the heart rate per unit time (that is, one minute) by multiplying the fundamental wave data by 60. Similarly, the microprocessor 45 also calculates the heart rate from the Doppler signal on the Q channel side. The microprocessor 45 averages the heart rate on the I-channel side and the heart rate on the Q-channel side to calculate the heart rate as a measurement result.

As another example, it is assumed that the heart rate range "81 bpm to 260 bpm" shown in FIG. 3 is set as the reference heart rate range. In this case, the heart rate of the living body is extracted by the same process as when the heart rate range "63 bpm to 260 bpm" is set.

As another example, it is assumed that the heart rate range "45 bpm to 260 bpm" shown in FIG. 3 is set as the reference heart rate range. In this case, since it is difficult to distinguish between the heart rate and the high frequency frequency of respiration, the microprocessor 45 disables the process of removing the tertiary high frequency component based on the respiration rate.

Even when disabled in this way, if the respiratory rate is low, the third-order high frequency component of the respiration is removed by HPF64. However, if the respiratory rate is high, the third-order high frequency component of the respiration may not be removed by HPF64. This is because when the respiratory rate is large, the frequency of the third-order high-frequency component of the respiration becomes large, and the frequency deviates from the cutoff band of HPF64. Therefore, it is preferable that the heart rate is measured based on the detection signal when the respiratory rate is small.

As an example, when the respiratory rate is 14 bpm, the tertiary high frequency component of the respiration is 42 bpm (= 0.7 Hz). Therefore, when the cutoff band "0.8 Hz or less" corresponding to the heart rate range "45 bpm to 260 bpm" is set to HPF64, the tertiary high frequency component of 42 bpm (= 0.7 Hz) is removed by HPF64. In this way, when the respiratory rate is smaller than the predetermined value, or when the amplitude of the respiration is smaller than the predetermined value, the third-order high-frequency component of the respiration is removed by the HPF64, and therefore, based on the detection signal at this time. The heart rate is measured.

The microprocessor 45 detects the frequency component having the highest signal intensity (peak) from the frequency distribution data generated from the detection signal when the respiratory rate is low as the fundamental wave data. After that, the microprocessor 45 calculates the heart rate per unit time (that is, one minute) by multiplying the fundamental wave data by 60. Similarly, the microprocessor 45 also calculates the heart rate from the Doppler signal on the Q channel side. The microprocessor 45 averages the heart rate on the I-channel side and the heart rate on the Q-channel side to calculate the heart rate as a measurement result.

[Summary of the second embodiment]
As described above, the measuring device 100 according to the present embodiment removes the frequency component corresponding to an integral multiple (for example, 3 times or more) of the respiratory rate from the signal component obtained by frequency-decomposing the Doppler signal. Measure the heart rate of the living body above. As a result, the measuring device 100 is not affected by the tertiary frequency component of respiration, and the heart rate of the living body can be extracted more accurately.

<Third embodiment>
[Overview]
In the measuring device 100 according to the first and second embodiments, the reference heart rate range is preset by the user. On the other hand, in the measuring device 100 according to the third embodiment, the reference heart rate range is automatically set. As a result, not only the heart rate can be accurately measured, but also the operability of the measuring device 100 is improved.

Since the other points such as the hardware configuration of the measuring device 100 according to the third embodiment are the same as those of the measuring device 100 according to the first and second embodiments, the description thereof will not be repeated below. ..

[Control structure of measuring device 100]
The control structure of the measuring device 100 will be described with reference to FIG. FIG. 11 is a flowchart showing a heart rate measurement process according to the third embodiment. The process of FIG. 11 is realized by executing a program by the microprocessor 45 of the measuring device 100. In other aspects, some or all of the processing may be performed by circuit elements or other hardware.

Since the processes other than steps S162 and S164 are as described in FIGS. 7 and 10, the description thereof will not be repeated.

In step S162, the microprocessor 45 determines whether or not the heart rate meets a predetermined condition. As an example, when the measured heart rate is the heart rate range specified in the heart rate information 122 (see FIG. 3) and belongs to the heart rate range higher than the reference heart rate range, the predetermined condition is satisfied. It is filled. Alternatively, when the measured heart rate is the heart rate range defined in the heart rate information 122 and belongs to the heart rate range in the lower peripheral range than the reference heart rate range, the predetermined condition is satisfied. Alternatively, when the heart rate falls below the predetermined lower limit value, or when the heart rate exceeds the predetermined upper limit value, it is assumed that the heart rate cannot be measured, and the predetermined condition is satisfied.

In step S162, if the microprocessor 45 determines that the heart rate meets a predetermined condition (YES in step S162), the microprocessor 45 switches control to step S170. Otherwise (NO in step S162), the microprocessor 45 switches control to step S164.

In step S164, the microprocessor 45 changes the reference heart rate range according to a preset rule. The method of determining the new reference heart rate range is arbitrary. In the following, a method for determining a new reference heart rate range will be described. In the following, for convenience of explanation, the heart rate range “45 bpm to 260 bpm” defined in the heart rate information 122 (see FIG. 3) is also referred to as a first reference heart rate range. The heart rate range "63 bpm to 260 bpm" defined in the heart rate information 122 is also referred to as a second reference heart rate range. The heart rate range "81 bpm to 260 bpm" defined in the heart rate information 122 is also referred to as a third reference heart rate range.

As an example, it is assumed that the first reference heart rate range is selected as the current set value. In this case, when the heart rate measured in a predetermined cycle is included in the second reference heart rate range or the third reference heart rate range a predetermined number of times (for example, three times), the microprocessor 45 determines the second reference heart rate range or the third reference heart rate range. Select the reference heart rate range as the new setting. Preferably, among the second and third reference heart rate ranges, the second reference heart rate range is selected as a new set value. This is because if the reference heart rate range is significantly changed from the first reference heart rate range to the third reference heart rate range, the cutoff band of HPF64 may change significantly and the primary high frequency component of the heart rate may be removed by HPF64. Because there is.

As another example, it is assumed that the second reference heart rate range is selected as the current setting value. In this case, when the heart rate measured in a predetermined cycle is included in the third reference heart rate range for a predetermined number of times (for example, three times), the microprocessor 45 has a third reference heart rate range that is the next narrowest to the second reference heart rate range. Is selected as the new setting value. In this way, the microprocessor 45 identifies the narrowest heart rate range next to the currently set reference heart rate range from the heart rate ranges defined in the heart rate information 122, and uses the heart rate range as a new reference heart rate range. Set.

As another example, it is assumed that the second reference heart rate range is selected as the current setting value. In this case, when the heart rate measured in a predetermined cycle is included in the first reference heart rate range for a predetermined number of times (for example, three times), the microprocessor 45 has a first reference heart rate range that is the next widest to the second reference heart rate range. Is selected as the new setting value.

As another example, it is assumed that the third reference heart rate range is selected as the current setting value. In this case, when the heart rate measured in a predetermined cycle is included in the first reference heart rate range or the second reference heart rate range a predetermined number of times (for example, three times), the microprocessor 45 determines the first reference heart rate range or the second reference heart rate range. Select the reference heart rate range as the new setting. The Doppler sensor 40 can easily detect unnecessary movements of the living body, which may increase the heart rate as a measurement result. Even in such a case, since the function that can appropriately narrow the reference heart rate range is implemented, the heart rate can be accurately measured.

In the above description, an example in which the cutoff band set in the HPF64 is changed based on the heart rate information 122 (see FIG. 3) has been described, but the method of changing the cutoff band of the HPF64 is not limited to this. .. For example, the microprocessor 45 may shift the cutoff band set in the HPF 64 to a predetermined percentage low frequency side. The predetermined percentage is, for example, a value larger than 0% and 20% or less. By slightly shifting the cutoff band of the HPF64 to the low frequency side, the range in which the heart rate ranges overlap between the low frequency side and the high frequency side becomes large, and the switching of the heart rate range becomes smoother.

Further, for the above-mentioned HPF64, either an IIR (Infinite Impulse Response) type filter or an FIR (Finite Impulse Response) type digital filter can be adopted, but an IIR type filter is preferably adopted. As a result, the sampling cycle and the calculation speed are increased, and the switching of the cutoff band of the HPF64 becomes smooth. As a result, the heart rate can be measured stably and the heart rate can be measured at a faster sampling rate.

Further, the above-mentioned processing described for HPF64 can also be applied to LPF65.

[Summary of the third embodiment]
As described above, the measuring device 100 according to the present embodiment automatically switches the cutoff band of the HPF64. As a result, not only the heart rate can be accurately measured, but also the operability of the measuring device 100 is improved.

It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

21 Oscillator, 22A, 22B, 145A, 145B, 145C, 145D Amplifier, 25 Transmit Antenna, 30 Receive Antenna, 32I, 32Q Mixer, 33I, 33Q, 65, 65I, 65Q, 71I, 71Q LPF, 38 90 Degree Phase Shift Instrument, 40 Doppler sensor, 41 analog signal processing circuit, 43 converter, 45 microprocessor, 50 body motion detector, 52 output control unit, 55 network, 60 heart rate calculation unit, 64, 64I, 64Q, 143A, 143B, 143C, 143D HPF, 66I, 66Q, 72I, 72Q fundamental wave detection unit, 67 setting unit, 68 heart rate extraction unit, 70 breath calculation unit, 73 breath extraction unit, 100 measuring device, 122 heart rate information, 124 reference heart rate range, 149A, 149B , 149C, 149D signal processing circuit, 152 control circuit, 154 memory, 156 speaker, 158 communication interface, 200 terminal device, 1000 measurement system.

Claims (7)

It is a measuring device for measuring the heart rate of a living body.
A Doppler sensor for irradiating the living body with microwaves, receiving the reflected waves of the microwaves, and outputting a Doppler signal indicating a frequency difference or a phase difference between the microwaves and the reflected waves.
A high-pass filter for removing low-frequency components in the set cutoff band from the Doppler signal, and
A reference heart rate range that can include the heart rate of the living body is acquired, and heart rate information that associates a frequency band with each heart rate range of the living body is acquired, and the frequency associated with the reference heart rate range in the heart rate information. A setting unit for setting the band as the cutoff band,
A heart rate extraction unit for determining the heart rate of the living body based on the frequency component of the heart rate signal obtained by removing the low frequency component of the set cutoff band from the Doppler signal .
A low-pass filter for removing high-frequency components in a frequency higher than the cutoff band from the Doppler signal,
A respiratory extraction unit for determining the respiratory rate of the living body is provided based on the frequency component of the respiratory signal obtained by removing the high frequency component from the Doppler signal.
The heart rate extraction unit is a measuring device that removes a signal component having a cycle corresponding to an integral multiple of the respiratory rate from the heart rate signal and determines the heart rate of the living body based on the removed heart rate signal. Based on the change of the reference heart rate range, the setting unit newly identifies a frequency band corresponding to the changed reference heart rate range from the heart rate information, and sets the frequency band as the cutoff band of the high-pass filter. The measuring device according to claim 1, which is reset as. The setting unit shifts the cutoff band set in the high-pass filter to a predetermined percentage low frequency side when the heart rate determined by the heart rate extraction unit satisfies a predetermined condition. 1 or the measuring device according to claim 2. When the heart rate of the living body satisfies a predetermined condition, the setting unit identifies a heart rate range next to the reference heart rate range from the heart rate ranges specified in the heart rate information, and the heart rate range is the narrowest. The measuring device according to claim 1 or 2, wherein the heart rate range is acquired as a new reference heart rate range. Heart rate determined by the heartbeat extraction unit, wherein if a heartbeat range defined in the heartbeat information belonging to the heartbeat range of high-frequency range than the reference heartbeat range, or the heartbeat extractor is the The measuring device according to claim 3 or 4, wherein the predetermined condition is satisfied when the heart rate of the living body cannot be extracted. It is a measurement method for measuring the heart rate of a living body.
A step of irradiating the living body with a microwave, receiving the reflected wave of the microwave, and outputting a Doppler signal representing a frequency difference or a phase difference between the microwave and the reflected wave.
The step of removing the low frequency component of the set cutoff band from the Doppler signal, and
A reference heart rate range that can include the heart rate of the living body is acquired, and heart rate information that associates a frequency band with each heart rate range of the living body is acquired, and the frequency associated with the reference heart rate range in the heart rate information. The step of setting the band as the cutoff band,
A step of measuring the heart rate of the living body based on the frequency component of the heart rate signal obtained by removing the low frequency component of the set cutoff band from the Doppler signal .
A step of removing a high frequency component in a frequency higher than the cutoff band from the Doppler signal,
A step of determining the respiratory rate of the living body based on the frequency component of the respiratory signal obtained by removing the high frequency component from the Doppler signal is provided.
In the step of measuring the heart rate of the living body, a signal component having a cycle corresponding to an integral multiple of the respiratory rate is removed from the heart rate signal, and the heart rate of the living body is determined based on the heart rate signal after the removal. Measurement method , including steps. It is a measurement program for measuring the heart rate of a living body.
The measurement program is applied to the measuring device.
A step of irradiating the living body with a microwave, receiving the reflected wave of the microwave, and outputting a Doppler signal representing a frequency difference or a phase difference between the microwave and the reflected wave.
The step of removing the low frequency component of the set cutoff band from the Doppler signal, and
A reference heart rate range that can include the heart rate of the living body is acquired, and heart rate information that associates a frequency band with each heart rate range of the living body is acquired, and the frequency associated with the reference heart rate range in the heart rate information. The step of setting the band as the cutoff band,
A step of measuring the heart rate of the living body based on the frequency component of the heart rate signal obtained by removing the low frequency component of the set cutoff band from the Doppler signal .
A step of removing a high frequency component in a frequency higher than the cutoff band from the Doppler signal,
Based on the frequency component of the respiratory signal obtained by removing the high frequency component from the Doppler signal, the step of determining the respiratory rate of the living body is performed .
In the step of measuring the heart rate of the living body, a signal component having a cycle corresponding to an integral multiple of the respiratory rate is removed from the heart rate signal, and the heart rate of the living body is determined based on the heart rate signal after the removal. A measurement program that includes steps that include.

Images