Biological information detection device

Abstract

To provide a biological information detection device capable of appropriately detecting biological information on a person to be measured.SOLUTION: A biological information detection device 1 includes: a signal acquisition part 10 for acquiring a signal including components corresponding to motion of a heart of a person to be measured as a heartbeat signal; and a signal processing part 20 for acquiring biological information on the person to be measured on the basis of the heartbeat signal. The signal processing part 20 removes components to be equal to or less than a first frequency as a first noise component from the heartbeat signal with frequencies to be a lower limit value or less of frequencies assumed at the motion of a heart of the person to be measured as the first frequency. The signal processing part 20 specifies a peak frequency in a first processed signal after removing the first noise component from the heartbeat signal, and removes components outside a passband as a second noise component from the first processed signal with a prescribed frequency band including the peak frequency as the passband. Then, the signal processing part 20 detects biological information on the basis of a second processed signal after removing the second noise component from the first processed signal.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a biological information detection device. [Background technology]

[0002] Conventionally, a known biological information detection device detects the heartbeat characteristics of a subject as biological information by irradiating radio waves toward the subject's body, receiving reflected waves from the body surface, and processing the waveform of the received waves (see, for example, Patent Document 1). The device described in Patent Document 1 extracts a respiratory signal by applying a low-pass filter to the heartbeat signal extracted from the received waves, and determines the harmonic components of the respiratory signal. The device then applies a high-pass filter to the received waves to remove the harmonic components of the respiratory signal from the extracted signal, thereby detecting a signal corresponding to the subject's heart movement. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5454593 Summary of the Invention [Problem to be solved by the invention]

[0004] However, as described in Patent Document 1, when removing the harmonic components of the respiratory signal from the heartbeat signal corresponding to the received wave, if the harmonics of the respiratory signal interfere with a signal correlated with the heart's movement, the signal correlated with the heart's movement is also removed when removing the harmonics. This is undesirable because it can lead to a decrease in the detection accuracy of the subject's biological information.

[0005] An object of the present disclosure is to provide a biological information detection device that can appropriately detect biological information of a subject. [Means for solving the problem]

[0006] The invention described in claim 1 is A biological information detection device, a signal acquiring unit (10, 10A) that acquires a signal including a component corresponding to the movement of the subject's heart as a heartbeat signal; a signal processing unit (20, 20A) for determining biological information of the subject based on the heartbeat signal; The signal processing unit a first filter unit (23, 23A) that defines a frequency equal to or lower than a lower limit of a frequency assumed to represent the heart movement of the subject as a first frequency, and removes components equal to or lower than the first frequency as first noise components from the heartbeat signal; a peak identifying unit (24, 24A) that identifies a peak frequency in a first processed signal obtained after removing a first noise component from the heartbeat signal; a second filter unit (25, 25A) that sets a predetermined frequency band including the peak frequency as a pass band and removes components outside the pass band from the first processed signal as second noise components; and an information detection section (26, 26A) that detects biological information based on a second processed signal obtained after removing a second noise component from the first processed signal, as a functional section.

[0007] The biological information detection device of the present disclosure removes from the heartbeat signal a first noise component that is below the lower limit of a frequency expected to represent cardiac movement, thereby removing low-frequency components in the heartbeat signal that are unrelated to cardiac movement as noise. Additionally, the biological information detection device uses a frequency band that includes the peak frequency of the first processed signal from which the first noise component has been removed as a passband, and removes from the first processed signal a second noise component that falls outside the passband. This allows the signal correlated with cardiac movement to be properly extracted even if harmonic components such as respiration interfere with the signal. Therefore, the biological information detection device of the present disclosure can properly detect the subject's biological information.

[0008] The invention described in claim 3 is A biological information detection device, a signal acquiring unit (10A) that acquires a signal including a component corresponding to the movement of the subject's heart as a heartbeat signal; a signal processing unit (20A) for determining biological information of the subject based on the heartbeat signal; the signal acquiring unit includes a plurality of receiving units (13A, 13B) so as to be able to acquire heartbeat signals at a plurality of parts of the subject's body; The signal processing unit compares the frequency characteristics of each of the multiple heartbeat signals acquired by the multiple receiving units, selects a heartbeat signal from the multiple heartbeat signals that is suitable for detecting biological information, and obtains the biological information based on the selected heartbeat signal.

[0009] In this way, by selecting a heart rate signal suitable for detecting biological information from among multiple heart rate signals corresponding to multiple body parts, even if harmonics of the respiratory signal interfere with the signal correlated with cardiac activity, the signal correlated with cardiac activity can be appropriately extracted. Therefore, the biological information detection device of the present disclosure can appropriately detect the biological information of the subject.

[0010] The reference symbols in parentheses attached to each component indicate an example of the correspondence between the component and the specific components described in the embodiments described below. [Brief explanation of the drawings]

[0011] [Figure 1] 2 is a schematic diagram showing an example of mounting a signal acquisition unit included in the biological information detection device according to the first embodiment on a vehicle. FIG. [Figure 2] 1 is a schematic configuration diagram of a biological information detection device according to a first embodiment. [Figure 3] FIG. 2 is an explanatory diagram for explaining an example of reception power corresponding to a received wave. [Figure 4] 10 is an explanatory diagram for explaining a heartbeat signal including a component corresponding to the movement of the subject's heart. FIG. [Figure 5] FIG. 10 is an explanatory diagram for explaining an error in RRI. [Figure 6] 4 is a flowchart showing the flow of signal processing executed by a signal processing unit included in the biological information detecting device according to the first embodiment. [Figure 7]FIG. 4 is an explanatory diagram for explaining the removal range of frequencies removed by the first filter section. [Figure 8] FIG. 10 is an explanatory diagram for explaining the removal range of frequencies removed by the second filter section. [Figure 9] 10 is a schematic side view showing an example of mounting a signal acquisition unit included in a biological information detection device according to a second embodiment on a vehicle. FIG. [Figure 10] 10 is a schematic plan view showing an example of mounting a signal acquiring unit included in a biological information detecting device according to a second embodiment on a vehicle. FIG. [Figure 11] FIG. 10 is a schematic configuration diagram of a biological information detection device according to a second embodiment. [Figure 12] 10 is a flowchart showing the flow of signal processing executed by a signal processing unit included in a biological information detecting device according to a second embodiment. [Figure 13] FIG. 10 is an explanatory diagram for explaining a method of selecting a heartbeat signal executed by a signal processing unit included in a biological information detecting device according to a second embodiment. [Figure 14] FIG. 11 is a schematic diagram showing an example of mounting a signal acquisition unit included in a biological information detection device according to a third embodiment on a vehicle. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following embodiments, parts that are the same as or equivalent to those described in the preceding embodiments will be given the same reference numerals, and their description may be omitted. Furthermore, in the embodiments, when only some of the components are described, the components described in the preceding embodiments can be applied to the remaining components. The following embodiments can be partially combined with each other, even if not specifically stated, as long as there is no particular problem with the combination.

[0013] (First embodiment) This embodiment will be described with reference to Figures 1 to 8. In this embodiment, an example will be described in which a biological information detecting device 1 of the present disclosure is mounted on a vehicle VE, which is a moving body, to detect biological information of an occupant PS of the vehicle VE.

[0014] In recent years, as drivers age, there has been an increase in serious accidents caused by vehicles (VE) losing control due to sudden physical abnormalities. To prevent this, it is desirable to constantly monitor the driver's heart rate information with a sensor while the vehicle (VE) is running. Heart rate information can not only indicate physical abnormalities, but also reveal the function of the autonomic nervous system and can detect the stress of the person being measured.

[0015] Therefore, for example, by monitoring the stress of the occupant PS through heart rate information, it is possible to provide a comfortable in-vehicle environment by activating relaxation-promoting functions such as changing the air conditioning volume or activating the massage function of the seat SH according to the stress level.

[0016] Calculating the stress level of the person being measured requires the heart rate information, which includes the interval between each heartbeat, known as the heart rate interval (RRI). Heart rate intervals can be detected using contact sensors such as wearable sensors, but depending on the subject's preferences, wearing such sensors can be inconvenient and hinder the provision of a comfortable in-car environment. RRI is an abbreviation for RR Interval.

[0017] In consideration of these, the biological information detecting device 1 of this embodiment is configured to detect the heartbeat interval as biological information using a restrained sensor. The biological information detecting device 1 includes a signal acquiring unit 10 that acquires a signal including a component corresponding to the movement of the heart HE of the occupant PS as a heartbeat signal, and a signal processing unit 20 that calculates the heartbeat interval of the occupant PS as biological information based on the heartbeat signal.

[0018] The signal acquiring unit 10 is configured with a non-contact sensor that does not restrain the occupant PS. The signal acquiring unit 10 of this embodiment is configured to irradiate the body of the person being measured with low-frequency radio waves, for example, in the band of several MHz, and receive the radio waves that have passed through the body.

[0019] Specifically, as shown in FIG. 2 , the signal acquisition unit 10 includes a transmitter 11, a transmitting antenna 12, a receiving antenna 13, and a receiver 14. The transmitter 11 outputs an electrical signal of a predetermined frequency to the transmitting antenna 12 to generate radio waves to be emitted from the transmitting antenna 12. The transmitting antenna 12 is attached, for example, to the instrument panel IP of the vehicle VE. The transmitting antenna 12 can emit radio waves of the predetermined frequency toward the chest CH where the heart HE of the occupant PS is located. The receiving antenna 13 is attached, for example, to the seat SH on which the occupant PS sits. The receiving antenna 13 receives the radio waves emitted from the transmitting antenna 12 and transmitted through the body of the occupant PS as an electrical signal. The receiver 14 amplifies the electrical signal of the radio waves received by the receiving antenna 13 and outputs an electrical signal corresponding to the reception level of the radio waves. The received signal output from the receiver 14 is transmitted to the signal processing unit 20.

[0020] Here, the subject's body functions as a dielectric with respect to the radio waves. Therefore, when the radio waves pass through the subject's body, dielectric loss occurs in the electric field strength of the radio waves. Within the subject's body, the cardiac HE changes shape as it expands and contracts. Therefore, the dielectric loss occurring in the electric field strength of the radio waves radiated from the transmitting antenna 12, passing through the subject's cardiac HE, and received by the receiving antenna 13 changes depending on the movement of the cardiac HE. Thus, the strength of the received signal received by the receiving antenna 13 includes a component that changes periodically depending on the movement of the cardiac HE. In this way, the signal acquiring unit 10 can acquire a signal including a component corresponding to the movement of the subject's cardiac HE as a heartbeat signal.

[0021] The signal processing unit 20 is configured to detect biological information of the subject based on the heartbeat signal acquired by the receiver 14. The signal processing unit 20 is configured by a computer including a processor that performs control processing and arithmetic processing, and a memory that stores programs, data, etc. The processor is configured by a CPU or MPU. The memory includes various non-transitory tangible storage media such as ROM, RAM, non-volatile rewritable memory, etc.

[0022] The signal processing unit 20 of this embodiment is configured to detect the heartbeat interval of the subject based on the heartbeat signal acquired by the receiver 14. For example, when the heart rate is 60 beats per minute, the heartbeat interval is 1000 ms. Normally, the heartbeat interval varies from beat to beat and also differs from person to person, but is generally about 800 to 1200 ms when at rest. In order to estimate the stress level of the subject based on the heartbeat interval, it is necessary to measure the heartbeat interval with an accuracy of about several ms.

[0023] On the other hand, when detecting the displacement of the subject's body surface or inside the body using radio waves as in the present invention, components due to breathing as well as the movement of the heart's HE are superimposed on the time waveform of the heartbeat signal as disturbances, as shown in Figure 3. The reason components due to breathing are superimposed is because the radio wave environment changes due to the displacement of the body surface and inside the body caused by breathing, which changes the received power. Note that when the subject is at rest, only breathing is present, but when the body is moving, the combined components due to the body movement are superimposed on the heartbeat signal as disturbances.

[0024] Other frequency components caused by breathing and other movements have large amplitudes relative to the heartbeat, as shown in Figure 4. This causes the peak position of the time waveform of the heartbeat signal to be shifted by several ms to several tens of ms from the peak position of the heartbeat. As a result, an error occurs in the heartbeat interval, as shown in Figure 5. Such an error is undesirable because it can lead to an incorrect determination of stress levels. Therefore, applications that utilize stress monitors need a means to remove disturbances such as respiratory components.

[0025] Taking these into consideration, the signal processing unit 20 of this embodiment is configured to remove disturbances such as respiratory components contained in the heartbeat signal, and to determine the heartbeat interval based on the heartbeat signal from which the disturbances have been removed.

[0026] The signal processing unit 20 includes, as functional units for realizing the above-mentioned various functions, a waveform acquisition unit 21, a frequency analysis unit 22, a first filter unit 23, a peak identification unit 24, a second filter unit 25, and an information detection unit 26. In other words, the signal processing unit 20 functions as the waveform acquisition unit 21, the frequency analysis unit 22, the first filter unit 23, the peak identification unit 24, the second filter unit 25, the information detection unit 26, etc., when the processor executes a program stored in the memory.

[0027] The waveform acquisition unit 21 is a functional unit that stores the time change of the heartbeat signal in a memory and obtains the time change as a time waveform of the heartbeat signal. The frequency analysis unit 22 is a functional unit that performs frequency analysis, such as fast Fourier transform (i.e., FFT) or discrete wavelet transform, on the time waveform of the heartbeat signal to generate data indicating the frequency characteristics of the heartbeat signal. The first filter unit 23 is a functional unit that defines a frequency equal to or lower than a lower limit of a frequency expected as the movement of the subject's heart HE as a first frequency and removes components equal to or lower than the first frequency as first noise components from the heartbeat signal. The peak identification unit 24 is a functional unit that identifies a peak frequency in the first processed signal obtained after removing the first noise components from the heartbeat signal. The second filter unit 25 is a functional unit that defines a predetermined frequency band including the peak frequency as a pass band and removes components outside the pass band as second noise components from the first processed signal. The information detection unit 26 is a functional unit that detects the heartbeat interval, which is biological information, based on the second processed signal obtained after removing the second noise components from the first processed signal.

[0028] Next, the signal processing executed by the signal processing unit 20 will be described with reference to the flowchart of Fig. 6. The control routine shown in Fig. 6 is executed by the signal processing unit 20 periodically or irregularly when the start switch of the vehicle VE is turned on.

[0029] 6, in step S100, the signal processing unit 20 acquires the heartbeat signal output from the receiver 14 as a received wave received by the receiving antenna 13. Specifically, the signal processing unit 20 operates the signal acquiring unit 10 to radiate radio waves from the transmitting antenna 12. Then, the signal acquiring unit 10 receives the radio waves radiated from the transmitting antenna 12 and transmitted through the body of the occupant PS as the heartbeat signal.

[0030] Next, in step S110, the signal processing unit 20 acquires the time waveform of the heartbeat signal. For example, the signal processing unit 20 stores the heartbeat signal in a memory as needed, and obtains the time waveform of the heartbeat signal based on the accumulated data of the heartbeat signal stored in the memory.

[0031] Next, in step S120, the signal processing unit 20 generates data indicating the frequency characteristics of the heartbeat signal by performing frequency analysis such as fast Fourier transform on the time waveform of the heartbeat signal. Then, in step S130, the signal processing unit 20 defines a frequency equal to or lower than the lower limit of the frequency expected to represent the movement of the heart HE of the occupant PS as a first frequency, and removes components equal to or lower than the first frequency as first noise components from the heartbeat signal.

[0032] Here, the heartbeat cycle is, for example, 50 to 100 beats / min at rest and 100 to 150 beats / min during exercise, so the possible frequency range is about 0.8 to 3 Hz. On the other hand, the respiratory cycle is about 20 beats / min in an adult at rest, with a fundamental frequency of 0.3 Hz or less.

[0033] In light of this, the signal processing unit 20 of this embodiment, as shown in Fig. 7, sets the first frequency to 0.8 [Hz], which is the lower limit of the frequency expected to represent the movement of the heart HE of the occupant PS, and removes components caused by breathing that are equal to or lower than the first frequency from the heartbeat signal. Note that the first frequency may be set to 0.8 [Hz] or lower as long as it is possible to remove components caused by breathing. Furthermore, the signal processing unit 20 may be configured to remove components that are equal to or lower than the first frequency as first noise components from the heartbeat signal using a band-pass filter whose passband is within the range of possible heartbeat frequencies.

[0034] However, the components actually generated by breathing are not pure sine waves, and contain harmonic components that are twice or more the fundamental frequency. These double and triple harmonic components may overlap with the range of possible heartbeat frequencies. Therefore, if the harmonic components of breathing are identified and removed as noise, there is a risk that signals that are correlated with cardiac HE movements, such as heartbeats, will also be removed.

[0035] Taking this into consideration, the signal processing unit 20 sets the passband to a frequency band including the peak frequency of the first processed signal obtained by removing the first noise component from the heartbeat signal, and removes the second noise component outside the passband from the first processed signal.

[0036] Specifically, in step S140, the signal processing unit 20 identifies a peak frequency in the first processed signal after removing the first noise component from the heartbeat signal. Then, in step S150, the signal processing unit 20 sets a predetermined frequency band including the peak frequency as a pass band and removes components outside the pass band as second noise components from the first processed signal.

[0037] The signal processing unit 20 is configured to remove harmonic components of breathing contained in the first processed signal using a band-pass filter having a passband obtained by increasing or decreasing a specific frequency relative to the peak frequency of the first processed signal, as shown in Fig. 8. The specific frequency may be a predetermined fixed value or a variable value that changes depending on the peak frequency. The specific frequency may be set to, for example, half the value obtained by subtracting the lower limit of the frequency expected to represent the movement of the heart HE of the occupant PS from the peak frequency.

[0038] Next, in step S160, the signal processing unit 20 detects the heartbeat interval, which is biological information, based on the second processed signal obtained after removing the second noise component from the first processed signal. The signal processing unit 20 detects the time interval at which a peak component appears in the second processed signal as the heartbeat interval.

[0039] The biological information detection device 1 described above removes from the heartbeat signal the first noise component that is below the lower limit of the frequency expected to represent cardiac HE movement, thereby enabling the removal of low-frequency components unrelated to cardiac HE movement from the heartbeat signal as noise. Additionally, the biological information detection device 1 sets a passband that includes the peak frequency of the first processed signal from which the first noise component has been removed, and removes from the first processed signal the second noise component that falls outside this passband. This allows the signal correlated with cardiac HE movement to be properly extracted even if harmonic components such as respiration interfere with the signal. Therefore, the biological information of the subject can be properly detected.

[0040] Furthermore, the biological information detecting device 1 of this embodiment has the following features. (1) The biological information detection device 1 is configured to obtain, as biological information, the heartbeat interval corresponding to the time interval at which peak components appear in the second processed signal. This allows the subject's autonomic nervous function to be estimated, and the subject's physical condition and stress level to be estimated.

[0041] (2) The signal acquiring unit 10 of this embodiment is configured to irradiate radio waves of a predetermined frequency from the transmitting antenna 12 toward the subject and receive the radio waves that have penetrated the subject's body with the receiving antenna 13. Thus, by configuring the signal acquiring unit 10 with a radio wave-transmitting sensor, signals related to the subject's cardiac HE movement can be directly detected as fluctuations in the radio wave reception level. Therefore, the method implemented by the signal processing unit 20 of the first embodiment, i.e., the method of removing noise while leaving signals related to the subject's cardiac HE movement intact, is highly effective, allowing the subject's biological information to be calculated with high accuracy.

[0042] (Second embodiment) Next, a second embodiment will be described with reference to Figures 9 to 13. In this embodiment, differences from the first embodiment will be mainly described.

[0043] The signal acquiring unit 10A of this embodiment has "multiple receiving units" so as to be able to acquire heartbeat signals from multiple parts of the subject's body. Specifically, as shown in Figures 9 and 10, the signal acquiring unit 10A includes a transmitter 11, a first transmitting antenna 12A, a second transmitting antenna 12B, a first receiving antenna 13A, a second receiving antenna 13B, and a receiver 14.

[0044] The transmitter 11 outputs an electrical signal of a predetermined frequency to one of the first transmitting antenna 12A and the second transmitting antenna 12B to generate radio waves to be emitted from the other antenna. The transmitter 11 is connected to each of the transmitting antennas 12A, 12B via a transmitting switch SW_Tx of the switching circuit SW. Each of the transmitting antennas 12A, 12B is attached to a seat SH on which the occupant PS sits so that the radio waves are emitted toward the back of the occupant PS.

[0045] The receiver 14 amplifies the electrical signal of the radio waves received by one of the first receiving antenna 13A and the second receiving antenna 13B and outputs an electrical signal according to the reception level of the radio waves. The receiver 14 is connected to each of the receiving antennas 13A and 13B via the receiving switch SW_Rx of the switching circuit SW. Each of the receiving antennas 13A and 13B is attached to the seat SH on which the occupant PS sits so as to receive radio waves that have passed through the body surface of the occupant PS and are diffusely reflected by the heart HE, etc. In this embodiment, the first receiving antenna 13A and the second receiving antenna 13B constitute "multiple receiving units."

[0046] The switching circuit SW is a circuit that switches between a first state in which the transmitter 11 is connected to the first transmitting antenna 12A and the receiver 14 is connected to the first receiving antenna 13A, and a second state in which the transmitter 11 is connected to the second transmitting antenna 12B and the receiver 14 is connected to the second receiving antenna 13B. The switching circuit SW alternates between the first state and the second state in response to a control signal from the signal processing unit 20.

[0047] Here, the location of body surface displacement due to breathing differs depending on whether the person is thoracic or abdominal breathing. People with well-developed abdominal muscles tend to be abdominal breathers, while others tend to be thoracic breathers. Thoracic breathing moves the muscles on the chest CH side of the body, while abdominal breathing moves the muscles in the abdominal AB. Therefore, if the person being measured is thoracic breathing, the location of body surface displacement due to breathing will be near the chest CH, with almost no displacement near the abdominal AB. Also, if the person being measured is abdominal breathing, the location of body surface displacement due to breathing will be near the abdominal AB, with almost no displacement near the chest CH.

[0048] Taking these factors into consideration, the first receiving antenna 13A and the second receiving antenna 13B in this embodiment are disposed at different positions in the height direction. Specifically, the first receiving antenna 13A is attached to a chest support portion of the seat SH that is assumed to support the chest CH of the body of the occupant PS. Meanwhile, the second receiving antenna 13B is attached to an abdominal support portion of the seat SH that is assumed to support the abdomen AB of the body of the occupant PS. Note that with respect to the transmitting antennas 12A and 12B, the first transmitting antenna 12A is attached to the chest support portion of the seat SH, and the second transmitting antenna 12B is attached to the abdominal support portion of the seat SH.

[0049] As shown in FIG. 11, the signal processing unit 20A of this embodiment is configured to include a waveform acquisition unit 21A, a frequency analysis unit 22A, a first filter unit 23A, a peak identification unit 24A, a second filter unit 25A, and an information detection unit 26A, which are similar to those of the first embodiment, as well as a selection unit 27A.

[0050] The selector 27A is a functional unit that compares the frequency characteristics of each of the multiple heartbeat signals acquired via the receiving antennas 13A and 13B and selects a heartbeat signal suitable for detecting biological information from the multiple heartbeat signals. For example, the selector 27A compares components that are disturbances such as breathing contained in the multiple heartbeat signals acquired via the receiving antennas 13A and 13B and selects a heartbeat signal that is less affected by disturbances such as breathing as a heartbeat signal suitable for detecting biological information.

[0051] Next, the signal processing executed by the signal processing unit 20A will be described with reference to the flowchart of Fig. 12. The control routine shown in Fig. 12 is executed by the signal processing unit 20A periodically or irregularly when the start switch of the vehicle VE is turned on.

[0052] 12, in step S100A, the signal processing unit 20A acquires, from the receiver 14, heartbeat signals corresponding to the received waves received by the receiving antennas 13A and 13B. Specifically, the signal processing unit 20 operates the signal acquiring unit 10 to radiate radio waves from the transmitting antennas 12A and 12B at different timings. The signal acquiring unit 10 then receives, as heartbeat signals, the radio waves radiated from the transmitting antennas 12A and 12B and reflected from inside the body of the occupant PS. Hereinafter, the signal corresponding to the radio waves received by the first receiving antenna 13A will be referred to as a first heartbeat signal, and the signal corresponding to the radio waves received by the second receiving antenna 13B will be referred to as a second heartbeat signal.

[0053] Next, in step S110A, the signal processing unit 20A acquires the time waveform of each heartbeat signal. When the subject is performing chest breathing, each heartbeat signal has a time waveform as shown on the left side of FIG.

[0054] Next, in step S120A, the signal processing unit 20A generates data indicating the frequency characteristics of each heartbeat signal by performing frequency analysis such as fast Fourier transform on the time waveform of each heartbeat signal. When the subject performs chest breathing, the frequency characteristics of the first heartbeat signal are more affected by disturbances such as breathing than the frequency characteristics of the second heartbeat signal, as shown in the center of Fig. 13.

[0055] Next, in step S125A, the signal processing unit 20A compares the frequency characteristics of each heartbeat signal and selects a heartbeat signal suitable for detecting biological information from among the heartbeat signals. For example, as shown in Fig. 13, the signal processing unit 20A compares components that are disturbances such as breathing contained in each heartbeat signal and selects a heartbeat signal that is less affected by disturbances such as breathing as a heartbeat signal suitable for detecting biological information.

[0056] Subsequently, in step S130A, the signal processing unit 20A removes the first noise component from the signal selected as the heartbeat signal suitable for detecting biological information. The subsequent processes of steps S140A to S160A are the same as the processes of steps S140 to S160 described in the first embodiment, and therefore will not be described again.

[0057] The rest is the same as in the first embodiment. The biological information detecting device 1 of this embodiment can obtain the same effects as in the first embodiment that are achieved by a configuration common to or equivalent to the first embodiment.

[0058] Furthermore, the biological information detecting device 1 of this embodiment has the following features. (1) The signal acquisition unit 10A includes multiple receivers so that it can acquire heartbeat signals from multiple parts of the subject's body. The signal processing unit 20A compares the frequency characteristics of the multiple heartbeat signals acquired by the multiple receivers, selects one from the multiple heartbeat signals suitable for detecting biological information, and obtains biological information based on the selected heartbeat signal. This allows the signal correlated with the movement of the heart HE to be properly extracted, even if harmonic components of breathing interfere with the signal. Therefore, the biological information of the subject can be properly detected.

[0059] (2) Specifically, the signal processing unit 20A selects, from among multiple heartbeat signals, a heartbeat signal with a small component corresponding to the subject's respiration as a heartbeat signal suitable for detecting biological information. This allows for the extraction of a signal correlating with the movement of the heart HE based on a heartbeat signal that is less affected by the harmonic components of respiration. This significantly contributes to improving the accuracy of detecting the subject's biological information.

[0060] (3) Specifically, multiple receivers are arranged at different positions along the height of the subject, which makes it easier to select a heart rate signal that is less affected by respiration harmonic components.

[0061] (Modification of the second embodiment) The signal acquiring unit 10A of the second embodiment is configured to include two transmitters 11 corresponding to two antennas, i.e., the first transmitting antenna 12A and the second transmitting antenna 12B, and the transmitting switch SW_Tx of the switching circuit SW may be omitted. Note that, although the signal acquiring unit 10A includes two antennas, i.e., the first transmitting antenna 12A and the second transmitting antenna 12B, the present invention is not limited to this and may be configured to include one antenna, as in the first embodiment.

[0062] The signal acquisition unit 10A of the second embodiment is configured to have two receivers 14 corresponding to two antennas, namely, the first receiving antenna 13A and the second receiving antenna 13B, and the receiving switch SW_Rx of the switching circuit SW may be omitted.

[0063] The signal acquiring unit 10A in the second embodiment has been exemplified as one in which multiple receiving units are arranged at different positions in the height direction of the subject, but is not limited to this. For example, the signal acquiring unit 10A may include one in which multiple receiving units are arranged at different positions in the width direction of the subject.

[0064] The signal processing unit 20A of the second embodiment is configured to remove the first noise component and the second noise component from the selected signal by comparing the frequency characteristics of each of the multiple heartbeat signals acquired by the multiple receiving units, but this does not have to be the case.

[0065] (Third embodiment) Next, a third embodiment will be described with reference to Fig. 14. In this embodiment, differences from the first embodiment will be mainly described.

[0066] The signal acquisition unit 10 provided in the biometric information detection device 1 of the third embodiment is configured to irradiate high-frequency radio waves such as millimeter waves or microwaves onto the body of the subject, receive the reflected waves from the body surface, and detect the heart rate characteristics of the subject.

[0067] As shown in Fig. 14, the signal acquisition unit 10 of this embodiment has a transmitter 11, a transmitting antenna 12, a receiving antenna 13, and a receiver 14. The transmitting antenna 12 and the receiving antenna 13 of this embodiment are attached to the instrument panel IP of the vehicle VE. The receiving antenna 13 receives a wave radiated from the transmitting antenna 12 and reflected by the body surface of the occupant PS. The radio waves received by the receiving antenna 13 can capture minute changes on the body surface corresponding to the movement of the heart HE of the occupant PS.

[0068] The rest is the same as in the first embodiment. The biological information detecting device 1 of this embodiment can obtain the same effects as in the first embodiment that are achieved by a configuration common to or equivalent to the first embodiment.

[0069] (Other embodiments) Representative embodiments of the present disclosure have been described above, but the present disclosure is not limited to the above-described embodiments and can be modified in various ways, for example, as follows.

[0070] In the above-described embodiment, the various configurations of the biometric information detection device 1 have been described in detail, but the various configurations of the biometric information detection device 1 are not limited to those described above, and may differ in part from those described above.

[0071] Although the biological information detection device 1 of the above-described embodiment is configured to obtain a heartbeat interval as biological information, the biological information detection device 1 is not limited to this. For example, the biological information detection device 1 may be configured to obtain a heartbeat as biological information.

[0072] In the above embodiment, an example in which the biological information detection device 1 of the present disclosure is applied to a vehicle VE has been described, but the present disclosure is not limited to this, and the biological information detection device 1 of the present disclosure can be applied to vehicles other than a vehicle VE.

[0073] In the above-described embodiments, it goes without saying that the elements constituting the embodiments are not necessarily essential unless they are particularly explicitly stated as essential or are clearly considered essential in principle. In the above-described embodiments, when numerical values ​​such as the number, numerical value, amount, range, etc. of the components of the embodiments are mentioned, they are not limited to the specific number unless they are particularly explicitly stated as essential or are clearly limited to a specific number in principle. In the above-described embodiments, when the shape, positional relationship, etc. of the components, etc. are mentioned, they are not limited to the shape, positional relationship, etc. unless they are particularly explicitly stated or are clearly limited to a specific shape, positional relationship, etc. in principle.

[0074] The controller and method of the present disclosure may be implemented on a special-purpose computer by configuring a processor and memory programmed to perform one or more functions embodied in a computer program. The controller and method of the present disclosure may be implemented on a special-purpose computer by configuring a processor with one or more dedicated hardware logic circuits. The controller and method of the present disclosure may be implemented on one or more special-purpose computers configured with a processor and memory programmed to perform one or more functions in combination with a processor configured with one or more hardware logic circuits. The computer program may also be stored on a computer-readable non-transitory tangible storage medium as instructions executed by a computer. [Explanation of symbols]

[0075] 1. Biometric information detection device 10, 10A signal acquisition section 11 Transmitter 20, 20A signal processing section 23, 23A First filter section 24, 24A Peak identification section 25, 25A Second filter section 26, 26A Information detection section

Claims

1. A biological information detection device, a signal acquiring unit (10, 10A) that acquires a signal including a component corresponding to the movement of the subject's heart as a heartbeat signal; a signal processing unit (20, 20A) for determining biological information of the subject based on the heartbeat signal; The signal processing unit a first filter unit (23, 23A) that defines a frequency equal to or lower than a lower limit of a frequency assumed to represent the heart movement of the subject as a first frequency, and removes components equal to or lower than the first frequency as first noise components from the heartbeat signal; a peak identifying unit (24, 24A) that identifies a peak frequency in a first processed signal obtained after removing the first noise component from the heartbeat signal; a second filter unit (25, 25A) that sets a predetermined frequency band including the peak frequency as a pass band and removes components outside the pass band from the first processed signal as second noise components; an information detection unit (26, 26A) that detects the biological information based on a second processed signal obtained after the second noise component has been removed from the first processed signal, as a functional unit;

2. the signal acquiring unit includes a plurality of receiving units (13A, 13B) so as to be able to acquire the heartbeat signals at a plurality of parts of the body of the subject; 2. The biological information detection device according to claim 1, wherein the signal processing unit compares frequency characteristics of the plurality of heartbeat signals acquired by the plurality of receiving units, selects the heartbeat signal suitable for detecting the biological information from the plurality of heartbeat signals, and obtains the biological information based on the selected heartbeat signal.

3. A biological information detection device, a signal acquiring unit (10A) for acquiring a signal including a component corresponding to the movement of the subject's heart as a heartbeat signal; a signal processing unit (20A) for determining biological information of the subject based on the heartbeat signal; the signal acquiring unit includes a plurality of receiving units (13A, 13B) so as to be able to acquire the heartbeat signals at a plurality of parts of the body of the subject; The signal processing unit compares the frequency characteristics of each of the multiple heartbeat signals acquired by the multiple receiving units, selects from the multiple heartbeat signals the heartbeat signal that is suitable for detecting the biometric information, and obtains the biometric information based on the selected heartbeat signal.

4. 4. The biological information detection device according to claim 2, wherein the signal processing unit selects, from among the plurality of heartbeat signals, a heartbeat signal having a small magnitude of a component corresponding to the breathing of the subject as the heartbeat signal suitable for detecting the biological information.

5. The biological information detection device according to claim 2 or 3, wherein the plurality of receiving units include units disposed at different positions in a height direction of the subject.

6. 3. The biological information detection device according to claim 1, wherein the biological information includes a heartbeat interval corresponding to a time interval at which a peak component appears in the second processed signal.

7. The signal acquisition unit a transmitting antenna (12, 12A, 12B) for irradiating radio waves of a predetermined frequency toward the subject; a transmitter (11) that outputs an electrical signal to the transmitting antenna to generate a radio wave; a receiving antenna (13, 13A, 13B) for receiving radio waves irradiated from the transmitting antenna and transmitted through the surface of the body of the subject; 3. The biological information detection device according to claim 1, further comprising a receiver (14) that outputs, as the heartbeat signal, a signal corresponding to a reception level of the radio wave received by the receiving antenna.

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