Patent Application
20210007614
The present invention relates to a biological information measurement apparatus, method, and program for measuring biological information using, for example, a radio wave.
As an apparatus for measuring biological information using a radio wave, there has been known an apparatus that includes a transmission antenna and a reception antenna arranged to face a measurement site, transmits a radio wave (measurement signal) from the transmission antenna toward the measurement site (target object), and receives a reflected wave (reflected signal) of the transmitted radio wave by the measurement site, to measure biological information (see, for example, Patent Literature 1).
In the case of measurement, for example, the measurement site is generally a pulse wave (or a signal related to a pulse wave) as biological information, a wrist or an upper arm. In the case of performing measurement by wearing a wearable device on a wrist, the adoption of a configuration in which a transmission antenna and a reception antenna (collectively referred to as a “transmission-reception antenna pair”, as appropriate) are installed in a wrist-wearing strap of the device, so that a pulse wave signal is measured by the transmission-reception antenna pair, is assumed. In this configuration, the measurement of the biological information is greatly affected by a body motion, making it impossible to properly measure the biological information when a measurement target person (also referred to as a “user”) is moving his or her body. The inventors of the present invention have proposed an apparatus having a function of detecting a body motion together with biological information. However, since this type of apparatus uses a motion sensor such as an acceleration sensor to detect a body motion, the apparatus becomes large, complicated, and expensive.
To resolve the above drawback, the present invention, in one aspect, provides a biological information measurement apparatus, method, and program that allow for detection of a body motion of a user without the addition of another sensor device.
To resolve the above drawback, a biological information measurement apparatus according to a first aspect of the present invention includes: a transmitter configured to transmit a radio wave to a measurement site of a living body; a receiver configured to receive a reflected wave of the radio wave by the measurement site and output a waveform signal of the reflected wave; a feature extractor configured to extract information indicating a feature of a waveform from the waveform signal; and a body motion detector configured to detect a state of an occurrence of a body motion of the living body, affecting measurement of the biological information, based on the extracted information indicating the feature of the waveform.
According to the first aspect of the present invention, information indicating a feature of a waveform is extracted from a waveform signal obtained by transmitting and receiving a radio wave to and from a measurement site, and a state of an occurrence of a body motion of the living body affecting measurement of biological information is detected based on the extracted information indicating the feature of the waveform. Therefore, it is possible to detect a body motion of a user by using the existing configuration included in the biological information measurement apparatus without adding another sensing device such as an acceleration sensor. As a result, the apparatus can be rendered simple, compact, and inexpensive.
A second aspect of the present invention is the biological information measurement apparatus according to the first aspect, wherein the feature extractor is configured to extract information relating to an amplitude of the waveform signal as a feature of the waveform of the waveform signal, and the body motion detector is configured to determine that the body motion has occurred when an amplitude value of the waveform signal exceeds a preset first amplitude value for a time period longer than a preset first duration, based on the extracted information relating to the amplitude of the waveform.
A third aspect of the present invention is the biological information measurement apparatus according to the first aspect, wherein the feature extractor is configured to extract information relating to an amplitude of the waveform signal as a feature of the waveform of the waveform signal, and the body motion detector is configured to determine that the body motion has occurred when an amplitude value of the waveform signal is below a preset first amplitude value for a time period shorter than a preset first duration, based on the extracted information relating to the amplitude of the waveform.
A fourth aspect of the present invention is the biological information measurement apparatus according to the first aspect, wherein the feature extractor is configured to extract information relating to an amplitude of the waveform signal as a feature of the waveform of the waveform signal, and the body motion detector is configured to determine that the body motion has occurred when an amplitude value of the waveform signal exceeds a preset first amplitude value for a time period shorter than a preset first duration, based on the extracted information relating to the amplitude of the waveform.
A fifth aspect of the present invention is the biological information measurement apparatus according to the first aspect, wherein the feature extractor is configured to extract information relating to an amplitude of the waveform signal as a feature of the waveform of the waveform signal, and the body motion detector is configured to determine that the body motion has occurred when an amplitude value of the waveform signal is below a preset first amplitude value for a time period longer than a preset first duration, based on the extracted information relating to the amplitude of the waveform.
According to the second to fifth aspects of the present invention, the amplitude value of the waveform is extracted as a feature of the waveform signal, and the occurrence of the body motion is determined based on a duration of the variation of the amplitude value. Therefore, the occurrence of the body motion can be accurately determined by focusing on both the amplitude of the waveform signal and the duration thereof.
A sixth aspect of the present invention is the biological information measurement apparatus according to the first aspect, wherein the feature extractor is configured to extract information relating to a repetition cycle of the waveform signal as a feature of the waveform of the waveform signal, and the body motion detector is configured to determine that the body motion has occurred when the repetition cycle of the waveform signal exceeds a preset time range, based on the extracted information relating to the repetition cycle of the waveform.
According to the sixth aspect of the present invention, the repetition cycle of the waveform is extracted as a feature of the waveform signal, and the occurrence of the body motion is determined based on the variation of the repetition cycle. Therefore, the body motion can be determined through a relatively simple process, merely by monitoring the change in the repetition cycle of the waveform signal.
A seventh aspect of the present invention is the biological information measurement apparatus according to the first aspect, wherein the feature extractor is configured to extract information relating to an amplitude of the waveform signal as a feature of the waveform of the waveform signal, and the body motion detector is configured to determine that the body motion has occurred when an amplitude value of the waveform signal exceeds a preset first amplitude range, based on the extracted information relating to the amplitude of the waveform.
An eighth aspect of the present invention is the biological information measurement apparatus according to the first aspect, wherein the feature extractor is configured to extract information relating to an amplitude of the waveform signal as a feature of the waveform of the waveform signal, and the body motion detector is configured to determine that the body motion has occurred when an amplitude value of the waveform signal does not exceed a preset second amplitude range, based on the extracted information relating to the amplitude of the waveform.
According to the seventh or eighth aspect of the present invention, the amplitude value of the waveform is extracted as a feature of the waveform signal, and the occurrence of the body motion is determined based on the variation of the amplitude value. Therefore, the body motion can be determined through a relatively simple process, merely by monitoring a unique amplitude variation of the waveform signal.
A ninth aspect of the present invention is the biological information measurement apparatus according to the first aspect, wherein the feature extractor is configured to extract, as a feature of the waveform of the waveform signal, information relating to an amplitude of a waveform of the waveform signal in each repetition interval, and the body motion detector is configured to determine that the body motion has occurred when a difference between an amplitude value of a waveform in a first repetition interval and an amplitude value of a waveform in a second repetition interval, different from the first repetition interval, exceeds a preset second amplitude range, based on the extracted information relating to the amplitude of the waveform in each repetition interval of the waveform.
According to the ninth aspect of the present invention, the amplitude value of the waveform is extracted for each repetition interval of the waveform signal as a feature of the waveform of the waveform signal, and it is determined that the body motion has occurred when a difference in the amplitude value of the waveform between a plurality of different repetition intervals exceeds a preset range. Therefore, the occurrence of the body motion can be determined merely by monitoring the change in the amplitude value of the waveform between the repetition intervals of the waveform signal.
A tenth aspect of the present invention is the biological information measurement apparatus according to the first aspect, wherein the feature extractor is configured to extract, as a feature of the waveform of the waveform signal, information relating to a spectrum intensity of a predetermined frequency band for each preset time interval of the waveform signal, and the body motion detector is configured to determine that the body motion has occurred when the information relating to the spectrum intensity exceeds a preset range, based on the extracted information relating to the spectrum intensity.
According to the tenth aspect of the present invention, a spectrum intensity of a predetermined frequency band is detected as a feature of the waveform of the waveform signal for each fixed interval of the waveform signal, and the occurrence of the body motion is determined based on the spectrum intensity. Therefore, the occurrence of the body motion can be accurately determined by monitoring the spectrum intensity of the frequency component specific to the body motion.
An eleventh aspect of the present invention is the biological information measurement apparatus according to the first aspect, wherein the feature extractor is configured to extract, as a feature of the waveform of the waveform signal, information indicating a shape of a waveform of the waveform signal in each repetition interval, and the body motion detector is configured to determine that the body motion has occurred when a correlation value between the shape of the waveform extracted and a shape of a reference waveform stored in advance is equal to or less than a preset correlation value, based on the extracted information relating to the shape of the waveform.
According to the eleventh aspect of the present invention, the shape of the waveform of the waveform signal in each repetition interval is extracted as a feature of the waveform of the waveform signal, and the correlation value between the shape of the waveform extracted and the shape of the reference waveform is obtained for each repetition interval of the waveform signal, so that the occurrence of the body motion is determined based on the correlation value. Therefore, the occurrence of the body motion can be accurately determined by focusing on the change of the waveform shape of the waveform signal with respect to the shape of the reference waveform due to the body motion.
A twelfth aspect of the present invention is the biological information measurement apparatus according to the first aspect, wherein the feature extractor is configured to extract, as a feature of the waveform of the waveform signal, information indicating a shape of a waveform of the waveform signal in each repetition interval, and the body motion detector is configured to determine that the body motion has occurred when a correlation value between a shape of a waveform in a first repetition interval and a shape of a waveform in a second repetition interval, different from the first repetition interval, is equal to or less than a preset correlation value, based on the extracted information relating to the shape of the waveform.
According to the twelfth aspect of the present invention, the shape of the waveform of the waveform signal in each repetition interval is extracted as a feature of the waveform of the waveform signal, and the occurrence of the body motion is determined based on the correlation value between the waveform shapes in the repetition intervals. Therefore, the occurrence of the body motion can be accurately determined by focusing on the change of the waveform shape of the waveform signal between the respective repetition intervals due to the body motion.
A thirteenth aspect of the present invention is the biological information measurement apparatus according to any one of the first to eighth aspects, wherein the body motion detector is configured to periodically perform an operation of determining an occurrence of the body motion, and return to the operation of determining an occurrence of the body motion when it is not determined that the body motion has occurred continuously for a preset period of time, or when it is not determined that the body motion has occurred continuously for the preset number of cycles after the occurrence of the body motion is determined.
According to the thirteenth aspect of the present invention, when the occurrence of the body motion is detected, the body motion detector returns to the operation of determining an occurrence of a body motion only when such occurrence is not detected continuously for a predetermined period of time or continuously for a predetermined number of cycles. Therefore, the body motion detector does not instantly return to the operation of body motion detection when the occurrence of the body motion is not detected temporarily, whereby a highly stable operation of body motion detection can be performed.
A fourteenth aspect of the present invention is the biological information measurement apparatus according to any one of the first to ninth aspects, wherein the body motion detector further includes an operation control unit configured to stop power supply to at least one of the transmitter, the receiver, the feature extractor, or the body motion detector for a preset time period when the body motion occurrence is detected.
According to the fourteenth aspect of the present invention, when the body motion occurrence is detected, the power supply to each unit of the apparatus is stopped for a certain period of time, whereby it is possible to reduce power consumption waste caused by continuing the measurement under inappropriate conditions where body motion influence cannot be ignored.
A fifteenth aspect of the present invention is the biological information measurement apparatus according to the ninth aspect, wherein the body motion detector further includes an operation control unit configured to stop power supply to at least one of the transmitter, the receiver, the feature extractor, or the body motion detector from a time point when the occurrence of the body motion is detected to a time point when the body motion detector returns to the operation of determining the occurrence of the body motion.
According to the fifteenth aspect of the present invention, the power supply to each unit of the apparatus is stopped after the occurrence of the body motion is detected until the occurrence of the body motion is no longer detected. Therefore, the power supply can be stopped only during the period in which the body motion is being detected.
A sixteenth aspect of the present invention is the biological information measurement apparatus according to any one of the first to ninth aspects, further including an output unit configured to output a result of detection by the body motion detector.
According to the sixteenth aspect of the present invention, a detection result of the state of the occurrence of the body motion is output. Therefore, it is possible to, for example, reflect the detection result of the state of the occurrence of the body motion in the operation of measuring the biological information, present the detection result to the user, store the detection result in a storage, or transmit the detection result to an external apparatus; it is also possible to take various measures by using the detection result of the state of the occurrence of the body motion. For example, a result of measurement of the biological information obtained during a period in which the body motion has occurred can be discarded or unused as unreliable information. Also, it is possible to prompt the user to stop the body motion during measurement by presenting the detection result of the state of the occurrence of the body motion to the user. Furthermore, storing the state of the occurrence of the body motion in a storage, or transmitting the state of the occurrence of the body motion to an external apparatus, allows the user to understand his or her health management, or allows a healthcare worker in a remote area to monitor the user's health condition.
Specifically, according to each aspect of the present invention, it is possible to provide a biological information measurement apparatus, method, and program that allow for detection of a body motion of a user without the addition of another sensor device.
Hereinafter, an embodiment according to one aspect of the present invention (hereinafter, also referred to as “the present embodiment”) will be described based on the drawings.
(Configuration)
First, an example of a scenario to which the present invention is applied will be described.
In the example shown in
The measurement site TG is, for example, a portion of a human wrist including a radial artery. The biological information measurement apparatus 1 is, for example, a wristwatch-type wearable terminal, and is disposed so that the sensor unit 2 faces a palmar surface of the wrist when the apparatus is worn. For example, a pulse wave (or a signal related to a pulse wave) is measured as biological information. The measurement site TG may be rod-shaped such as an upper limb (wrist, upper arm, or the like) or a lower limb (ankle or the like), and may also be a trunk.
The sensor unit 2 is, for example, a pulse wave sensor that measures a pulse wave of the radial artery of the user, and includes a transmitter 3 and a receiver 4.
The transmitter 3 includes a transmission antenna element and transmitter circuitry, and transmits a radio wave as a measurement signal toward the measurement site TG.
The receiver 4 includes a reception antenna element and receiver circuitry, receives a reflected wave of the radio wave by the measurement site TG, and outputs a waveform signal of the reflected wave.
The feature extractor 1051 receives the waveform signal output from the receiver 4, generates a pulse wave signal based on the waveform signal, and then extracts a feature of a waveform from the pulse wave signal.
The body motion detector 1052 detects a state of an occurrence of a body motion based on the feature of the waveform of the pulse wave signal extracted by the feature extractor 1051. In this example, the state of an occurrence of a body motion indicates whether or not there is an occurrence of a body motion; however, it may also include a period of an occurrence of a body motion, a magnitude and direction of a body motion, and the like.
The output unit 5 outputs a detection result of the state of an occurrence of a body motion detected by the body motion detector 1052. For example, the output unit 5 generates a display message indicating that a body motion is occurring or prompting the body motion to stop based on the detection result of the state of an occurrence of a body motion, and outputs the display message to the display 50.
The display 50 includes, for example, a display and/or a speaker provided to the biological information measurement apparatus 1, and visually or auditorily presents the user with the display message output from the output unit 5. Alternatively, the display 50 may notify the user of the detection result by vibration. The display 50 may be provided separately from the biological information measurement apparatus 1 or may be omitted.
(Operation)
In the biological information measurement apparatus 1, the transmitter 3 transmits a radio wave as a measurement signal to the measurement site TG at a fixed cycle. Then, a reflected wave of the radio wave by the measurement site TG is received by the receiver 4 at the fixed cycle. The receiver 4 generates a waveform signal of the reflected wave and outputs the waveform signal to the feature extractor 1051. The radio wave to be transmitted by the transmitter 3 may be transmitted continuously or intermittently.
When the waveform signal is input from the receiver 4, the feature extractor 1051, for example, firstly converts the waveform signal into a digital signal, and then performs filtering processing for canceling an unnecessary wave component such as a noise component to generate a pulse wave signal. The pulse wave signal is a waveform signal representing the pulsation of the radial artery passing through the measurement site TG. Next, the feature extractor 1051 extracts a feature of a waveform from the pulse wave signal. For example, the feature extractor 1051 extracts an amplitude value from the waveform of the pulse wave signal. The feature of the waveform is not limited to an amplitude value, and a periodicity of the waveform, a spectrum intensity of the waveform in a predetermined frequency band, a shape of the waveform, and the like may also be extracted as a feature of the waveform. The feature extractor 1051 outputs information indicating the extracted feature of the waveform to the body motion detector 1052.
The body motion detector 1052 detects a state of an occurrence of a body motion based on the information indicating the feature of the waveform output from the feature extractor 1051. For example, the body motion detector 1052 determines an occurrence of a body motion based on whether or not the time during which the amplitude value of the waveform exceeds a threshold continues for a certain period or longer. The method of detecting a body motion is not limited to the above-described method. The occurrence of a body motion may also be detected based on, for example, whether or not the amplitude value of the waveform exceeds a range indicated by a predetermined threshold, whether or not a difference in the amplitude value between repetition intervals of the waveform exceeds a predetermined threshold, whether or not a change in the repetition cycle of the waveform exceeds a predetermined range, whether or not a spectrum intensity of a predetermined frequency band of the waveform exceeds a range indicated by a predetermined threshold, whether or not a correlation value between the shape of the detected waveform and a shape of a reference waveform or a correlation value of the waveform between respective repetition intervals exceeds a threshold.
The output unit 5 generates a display message indicating that a body motion is occurring or prompting the body motion to stop based on the information indicating the detection result of the state of an occurrence of a body motion reported by the body motion detector 1052, and outputs the display message to the display 50 for display.
The output unit 5 can also, for example, output the information indicating the detection result of the state of an occurrence of a body motion to a storage (not shown) for the purpose of storing the information in the storage, or output the information to an external apparatus via a network.
As described above, according to the application example, a feature of a waveform (e.g., an amplitude value) is extracted by the feature extractor 1051 from a pulse wave signal obtained by transmission and reception of a radio wave to and from the measurement site TG, and a state of an occurrence of a body motion is detected by the body motion detector 1052 based on the extracted feature of the waveform. Therefore, a body motion of a user can be detected without adding another motion sensor such as an acceleration sensor. As a result, the apparatus can be rendered simple, compact, and inexpensive.
In addition, a display message indicating that a body motion is occurring or prompting the body motion to stop, for example, is generated by the output unit 5 based on the information indicating the detection result of the body motion, and displayed on the display 50. As a result, the user can confirm his or her own motion state based on the display message and stop the body motion during measurement of the biological information.
Furthermore, the detection result of the state of an occurrence of a body motion, for example, is stored in a storage or transmitted to an external apparatus via a network by the output unit. As a result, the detection result of the state of an occurrence of a body motion can be used by a user to know the amount of movement and the like, or by a healthcare worker in a remote area to monitor the motion state of the user, for example.
It is also possible to perform processing for discarding or not using the biological information measured in a state where a body motion is detected, for example, based on the information indicating the detection result of the state of an occurrence of a body motion stored in the storage.
(1) Structure of Blood Pressure Monitor
As shown in
As shown in
In this example, the main body 10 is integrally provided at one end 20e of the strap 20 in the circumferential direction by way of integral molding. The strap 20 and the main body 10 may be separately formed, so that the main body 10 is integrally attached to the strap 20 via an engaging member (such as a hinge). In this example, an area in which the main body 10 is disposed is intended to correspond to a back surface (dorsal surface) 90b of the left wrist 90 in the worn state.
As can be seen in
A display 50 forming a display screen is provided on a top surface 10a of the main body 10 (i.e., surface farthest from the measurement site). In this example, the display 50 is formed of an organic EL (electroluminescence) display, and displays information related to blood pressure measurement, such as a result of blood pressure measurement, and other kinds of information in accordance with a control signal from a control unit (not shown). The display 50 is not limited to an organic EL display, and may be formed of another type of display such as an LCD (liquid crystal display).
A controller 52 for inputting an instruction from a user is provided on a side surface 10f of the main body 10 (a side surface on the left front side of
A transmitter-receiver 40 constituting first and second pulse wave sensors is provided at a portion of the strap 20 between one end 20e and the other end 20f in the circumferential direction. A transmission-reception antenna group 40E including the antennas TX1, TX2, RX1, and RX2 spaced from each other in the longitudinal direction X and the width direction Y of the strap 20 is mounted on a part of the inner peripheral surface 20a corresponding to the part of the strap 20 where the transmitter-receiver 40 is arranged. In this example, the range occupied by the transmission-reception antenna group 40E in the longitudinal direction X of the strap 20 is intended to correspond to the radial artery 91 of the left wrist 90 in the worn state (see
As shown in
When wearing the blood pressure monitor 1 on the left wrist 90, the user passes his or her left hand through the strap 20 in the direction indicated by the arrow A in
In the worn state, the transmission-reception antenna group 40E of the transmitter-receiver 40 includes two transmission antennas TX1 and TX2 and two reception antennas RX1 and RX2, which are spaced from each other substantially along the longitudinal direction of the left wrist 90 (corresponding to the width direction Y of the strap 20) and the circumferential direction of the left wrist 90 (corresponding to the longitudinal direction X of the strap 20), in a manner corresponding to the radial artery 91 of the left wrist 90, as shown in
In this example, the transmission antennas or the reception antennas have a pattern shape of a square of about 3 mm in length and width in a planar direction (i.e., the direction of the sheet of drawing in
Each of the transmission antennas TX1 and TX2 has a conductive layer for emitting a radio wave (not shown). A dielectric layer is attached along a surface of the conductive layer facing the left wrist 90 (The respective transmission antennas and reception antennas have the same configuration.) In the worn state, the conductive layer faces the palmar surface 90a of the left wrist 90, and the dielectric layer serves as a spacer to keep the distance between the palmar surface 90a of the left wrist 90 and the conductive layer constant. Thus, the biological information from the left wrist 90 can be accurately measured.
The conductive layer is made of, for example, a metal (copper or the like). The dielectric layer is made of, for example, polycarbonate, whereby the relative dielectric constant of the dielectric layer is uniformly set to εr≈3.0. The relative dielectric constant refers to a relative dielectric constant at a frequency of 24 GHz band of a radio wave used for transmission and reception.
The transmission-reception antenna group 40E described above may be configured to lie flat along the planar direction. Therefore, in the blood pressure monitor 1, the strap as a whole 20 can be configured to be thin.
In
(2) Functional Configuration of Blood Pressure Monitor 1
The blood pressure monitor 1 includes a plurality of sensor units and a processing unit 12. To simplify the illustration,
The first sensor unit 130-1 includes a pair of the transmission antenna TX1 and the reception antenna RX1, and transmitter circuitry TC1 and RC1 connected to the transmission antenna TX1 and the reception antenna RX1, respectively. The transmission antenna TX1 and the reception antenna RX1 both have directivity in the direction of the measurement site including the radial artery 91. The transmitter circuitry TC1 feeds a measurement signal to the transmission antenna TX1 at a constant cycle, thereby transmitting a radio wave of the measurement signal from the transmission antenna TX1 to the measurement site. The reception antenna RX1 receives a reflected wave of the radio wave of the measurement signal by the radial artery 91. The receiver circuitry RC1 generates a waveform signal corresponding to the reflected wave received by the reception antenna RX1 and outputs the waveform signal to the processing unit 12.
The configuration of each of the second to n-th sensor units 130-2 to 130-n is the same as that of the first sensor unit 130-1, and thus a description thereof will be omitted.
The processing unit 12 includes, for example, a hardware processor, such as a central processing unit (CPU), and a work memory, and includes pulse wave detectors 101-1, 101-2, . . . , 101-n (101-1 to 101-n), a PTT calculator 103, a blood pressure estimator 104, a body motion determination unit 105, and, as processing function units, an output unit 5 according to an embodiment. All these processing function units are implemented by causing the hardware processor to execute a program stored in a storage unit (not shown).
The pulse wave detectors 101-1 to 101-n capture the waveform signals output from the sensor units 130-1 to 130-n, respectively, to generate pulse wave signals PS1 to PSn, and output the pulse wave signals PS1 to PSn to the PTT calculator 103 and the body motion determination unit 105.
The PTT calculator 103 calculates, as a pulse transit time (PTT), a time difference between the pulse wave signals PS1 and PS2 output from any of the pulse wave detectors 101-1 to 101-n (e.g., 101-1, 101-2).
The blood pressure estimator 104 estimates a blood pressure value corresponding to the pulse transit time (PTT) calculated by the PTT calculator 103, based on the pulse transit time (PTT) calculated by the PTT calculator 103 and a correspondence equation representing a relationship between a PTT and a blood pressure value stored in a storage unit (not shown).
The body motion determination unit 105 extracts a feature of a waveform from the pulse wave signal output from the pulse wave detector 101-1. Then, based on the extracted feature of the signal waveform, the body motion determination unit 105 detects a state of an occurrence of a body motion (e.g., whether or not there is an occurrence of a body motion, a period of an occurrence of a body motion) affecting measurement of the biological information.
When it is determined that a body motion has occurred, the body motion determination unit 105 controls power supply circuitry to selectively cut power supply to the sensor units 130-1 to 130-n over a preset certain period of time from the detection time point or in a period from the detection time point until the body motion is no longer detected.
The output unit 5 generates a display message indicating that a body motion is occurring or prompting the body motion to stop, for example, based on the detection result of the state of an occurrence of a body motion by the body motion determination unit 105, so that the display message is displayed on a display (not shown).
The output unit 5 can also output information indicating the detection result of the state of an occurrence of a body motion, for example, to a storage (not shown) for the purpose of storing the information in the storage, or output the information to an external apparatus via a network. In this case, the output unit 5 may include other kinds of information, such as information indicating time, the ID of the user or the biological information measurement apparatus 1, and the acquired pulse wave signal, in the information indicating the detection result of the state of an occurrence of a body motion.
The blood pressure monitor 1 includes a sensing unit 13, a processing unit 12, a storage unit 14, an input/output interface 16, a communication interface 17, a display 50, and a controller 52. Among these components, the processing unit 12, the storage unit 14, the input/output interface 16, the communication interface 17, the display 50, and the controller 52 are provided in the main body 10.
The input/output interface 16 has, for example, a function of receiving an instruction input by a user via the controller 52 and outputting display data generated by the processing unit 12 to the display 50.
The communication interface 17 includes, for example, a wired or wireless interface, and enables transmission and reception of information to and from a terminal carried by a user, a server (not shown) on a cloud, or the like via a communication network NW. In the present embodiment, the network NW is the Internet, but is not limited thereto. The network NW may be another type of network such as an in-hospital local area network (LAN), or one-to-one communication using a USB cable or the like. The communication interface 17 may be an interface for a micro USB connector.
The storage unit 14 is a combination of a nonvolatile memory, such as an HDD (hard disk drive) or an SSD (solid state drive), that allows for write and read operations at any time, and a volatile memory, such as a RAM, as a storage medium, and includes a program storage (not shown), a correspondence equation storage 141, a measurement value storage 142, and a body motion storage 143 as storage areas necessary for implementing the present embodiment.
A correspondence equation representing a relationship between a pulse transit time (PTT) and a blood pressure value is stored in advance in the correspondence equation storage 141. The correspondence equation will be detailed later.
The measurement value storage 142 is used to store a log relating to a measurement result of a blood pressure value.
The body motion storage 143 is used to store information indicating the detection result of the state of an occurrence of a body motion.
The measurement value storage 142 and the body motion storage 143 need not necessarily be built in the biological information measurement apparatus 1, and may be provided in, for example, a mobile terminal carried by a user or an external storage device such as a server on a cloud. In this case, the blood pressure monitor 1 can access the measurement value storage 142 and the body motion storage 143 by communicating with the mobile terminal or the server via the communication network NW.
The sensing unit 13 includes a plurality of sensor units 130-1 to 130-n (hereinafter also collectively referred to as “sensor units 130”) as pulse wave sensors. As also described with reference to
As also described with reference to
The pulse wave detectors 101-1 to 101-n include AD converters ADC1 to ADCn and filters F1 to Fn, respectively. The AD converters ADC1 to ADCn convert the waveform signals output from the receiver circuitry RC1 to RCn, respectively, into digital signals. The filters F1 to Fn perform filtering processing for canceling noise components, for example, on the waveform signals converted into digital signals, thereby outputting pulse wave signals PS1 to PSn. The pulse wave signals represent pulsation of the radial artery 91 passing through the left wrist 90 at the arrangement position of the above transmission-reception antennas.
The body motion determination unit 105 includes a feature extractor 1051 and a body motion detector 1052.
The feature extractor 1051 receives the pulse wave signal PS1 output from at least one of the pulse wave detectors 101-1 to 101-n (in this example, the pulse wave detector 101-1), and extracts a feature of a waveform from the pulse wave signal PS1. The process of extracting the feature of the waveform will be detailed later.
The body motion detector 1052 receives information indicating the feature of the waveform extracted by the feature extractor 1051, and detects a state of an occurrence of a body motion affecting measurement of the pulse wave. The process of detecting the state of an occurrence of a body motion will also be detailed later.
(1) Measurement of Pulse Wave and Estimation of Blood Pressure
Next, an operation example of the blood pressure monitor 1 according to an embodiment of the present invention will be described.
The blood pressure monitor 1 transmits, using the first sensor units 130-1 to 130-n, radio waves as measurement signals at a constant cycle from the transmitter circuitry TC1 to TCn toward a plurality of different areas of the measurement site including the radial artery 91 via the transmission antennas TX1 to TXn. Then, reflected waves of the respective radio waves by the measurement site are received through the reception antennas RX1 to RXn, and waveform signals corresponding to the reflected waves are generated by the receiver circuitry RC1 to RCn. These waveform signals are input to the pulse wave detectors 101-1 to 101-n of the processing unit 12.
The pulse wave detectors 101-1 to 101-n of the processing unit 12 perform processing for converting into digital signals and filtering processing for canceling noise components on the waveform signals output from the receiver circuitry RC1 to RCn, thereby obtaining pulse wave signals PS1 to PSn. The pulse wave signals PS1 to PSn are input to the PTT calculator 103.
The PTT calculator 103 calculates a time difference between any pulse wave signals (e.g., PS1 and PS2) among the input pulse wave signals PS1 to PSn as a pulse transit time (PTT). For example, in the example shown in
The blood pressure estimator 104 performs processing for estimating a blood pressure value corresponding to the pulse transit time (PTT), calculated by the PTT calculator 103 based on the pulse transit time (PTT) calculated by the PTT calculator 103, and a correspondence equation representing a relationship between a PTT and a blood pressure value stored in the correspondence equation storage 141 of the storage unit 14.
For example, when a pulse transit time is represented as DT and blood pressure is represented as EBP, a correspondence equation Eq is provided as a known fractional function including a term of 1/DT2, as shown by:
EBP=α/DT
2+β (Eq. 1)
(where α and β each represent a known coefficient or constant).
As the correspondence equation Eq, another known correspondence equation, such as an equation including a term of 1/DT and a term of DT in addition to the term of 1/DT2, may be employed, as shown by:
EBP=α/DT
2
+β/DT+γDT+δ (Eq. 2)
(where α, β, γ, and δ each represent a known coefficient or constant).
The estimate value of the blood pressure calculated by the blood pressure estimator 104 is stored as a blood pressure log in the measurement value storage 142 via the output unit 5, for example. The estimate value of the blood pressure may be displayed on the display 50 by the output unit 5 via the input/output interface 16, for example. However, the estimate value of the blood pressure can be a mere reference value to be used as a trigger for prompting a more accurate blood pressure measurement.
For example, if the blood pressure monitor 1 has a further blood pressure measurement function adopting an oscillometric method, in addition to the blood pressure estimation function based on the PTT, it may determine whether or not the estimate value of the blood pressure based on the PTT exceeds a range indicated by a threshold, and, when determining that the estimate value of the blood pressure exceeds said range, activate the blood pressure measurement function adopting the oscillometric method to measure blood pressure more accurately. If the blood pressure monitor 1 does not have the blood pressure measurement function adopting the oscillometric method, a message indicating that the estimate value of the blood pressure based on the PTT exceeds the range indicated by a threshold may be displayed on the display 50 to prompt the user to perform blood pressure measurement using a separately prepared oscillometric blood pressure monitor.
(2) Detection and Output of State of Occurrence of Body Motion
In the blood pressure monitor 1, a process of detecting and outputting a state of an occurrence of a body motion is performed in parallel with the above-described process of calculating the PTT and estimating the blood pressure, as will be described below.
That is, the body motion determination unit 105 of the blood pressure monitor 1 acquires the pulse wave signal PS1 from any one of the pulse wave detectors 101-1 to 101-n (e.g., the pulse wave detector 101-1). Then, the body motion determination unit 105 extracts a feature of a waveform from the pulse wave signal PS1, and detects a state of an occurrence of a body motion affecting measurement of the biological information based on the extracted feature of the signal waveform. Multiple kinds of methods can be considered as a method of detecting a state of an occurrence of a body motion by extracting a feature of a waveform from the pulse wave signal. These methods will be detailed later.
When the occurrence of a body motion is detected, information indicating the detection result is passed from the body motion determination unit 105 to the output unit 5. Based on the detection result, the output unit 5 generates a display message indicating that a body motion is occurring or prompting the body motion to stop, for example, and sends the display message to the display 50 via the input/output interface 16. Thus, the display message is displayed on the display 50. As a result, the user can confirm his or her own motion state based on the display message and stop the body motion during the period of measurement of the pulse wave.
At the same time as or instead of displaying the display message on the display 50, a voice message such as “Measurement cannot be made. Don't move.” or a warning sound may be output from a speaker provided in the display 50. Instead of the warning sound, the blinking of a light or a vibration may also be used.
For example, the output unit 5 stores the detection result of the state of the occurrence of the body motion in the body motion storage 143. Therefore, by reading the information of the stored detection result and displaying it on the display 50 according to the user's operation, for example, the user can use the information to know whether or not there is a movement, the amount of movement, and the like. Evaluation of the degree of a body motion during sleep based on the detection result of the state of the occurrence of the body motion at night can also be used to evaluate the quality of sleep.
Furthermore, the information indicating the detection result of the state of the occurrence of the body motion is, for example, transmitted by the output unit 5 to an external apparatus via a network. In this case, the ID of the user or the blood pressure monitor 1, the measurement time, the waveform of the measured pulse wave, the calculated estimate value of the blood pressure, and the like are either included in or added to the information indicating the detection result of the state of the occurrence of the body motion, and subsequently transmitted. As a result, a family member or a healthcare worker in a remote area can monitor the motion state of the user. This is effective when remotely monitoring an elderly person, for example.
(3) Detection of State of Occurrence of Body Motion
(3-1) First Detection Method
In the first detection method, an amplitude value of a waveform is extracted as a feature of a waveform of a received pulse wave signal, and an occurrence and termination of a body motion affecting measurement of a pulse wave are detected based on the extracted amplitude value.
As shown in
In the first detection method, it is determined that a body motion has occurred when the time during which the amplitude value of the received pulse wave signal exceeds a preset threshold V_TH is longer than a preset time threshold T_TH. That is, when the time during which the reception signal intensity (voltage or the like) of a reflected wave exceeds a preset intensity threshold V_TH runs beyond the time threshold T_TH, it is determined that a body motion has occurred.
On the other hand, when the time during which the amplitude value of the pulse wave signal exceeds the threshold V_TH becomes shorter than the time threshold T_TH, it is determined that the body motion has stopped.
The body motion determination unit 105 of the processing unit 12, for example, turns on a body motion determination flag during a period in which it is determined that a body motion is occurring, and turns off the body motion determination flag during a period in which an occurrence of a body motion is not detected, thereby indicating the state of the occurrence of the body motion.
The above operation will be described in more detail. First, the blood pressure monitor 1 is in a state of performing a body motion occurrence detection operation (a state of monitoring whether or not an occurrence of a body motion is newly detected). In
Thereafter, it is determined that the time during which the signal intensity of the pulse wave signal exceeds the intensity threshold V_TH at a time point t13, and the signal intensity of the pulse wave signal exceeds the intensity threshold V_TH at a time point t14, has exceeded the time threshold T_TH (threshold-exceeded time>T_TH). It is presumed that this is because a noise component caused by the body motion is superimposed on the pulse wave signal (a low-frequency component of the body motion is superimposed on the waveform=there is a body motion). Therefore, it is determined that a body motion affecting measurement of the pulse wave has occurred, and the body motion determination flag is turned on at the time point t14. Since the body motion determination flag is on, the blood pressure monitor 1 shifts to a state of monitoring non-detection of a body motion occurrence rather than monitoring detection of such.
Subsequently, at a time point t15, the signal intensity of the pulse wave signal falls below the intensity threshold V_TH. However, since the condition for determining non-detection is not satisfied, the body motion determination flag is maintained to be on. At a time point t16, the signal intensity of the pulse wave signal exceeds the intensity threshold V_TH again, and at a time point t17, the intensity threshold-exceeded time exceeds the time threshold T_TH again (threshold-exceeded time>T_TH). It is determined that the body motion is continuing during this time, and the body motion determination flag is maintained to be on. Thereafter, at a time point t18, the time during which the signal intensity of the pulse wave signal exceeds the intensity threshold V_TH becomes less than the time threshold T_TH (threshold-exceeded time<T_TH). This is determined to be a phenomenon (i.e., no body motion) due to disappearance (or reduction) of the noise component caused by the body motion that is superimposed on the pulse wave signal.
In regard to the first detection method, however, it is not determined that the body motion has stopped immediately at the time point t18 in
As described above, in the first detection method, it is not immediately determined that the body motion has stopped when the time during which the amplitude of the waveform of the pulse wave signal exceeds the threshold V_TH becomes less than the time threshold T_TH, but after it is confirmed that the same situation is detected stably for a certain time (when “threshold-exceeded time<constant value” continues N_TH times (twice, in
Under the control of the body motion detector 1052, the processing unit 12 of the blood pressure monitor 1 firstly determines in step S20 whether or not an amplitude value of a waveform of a pulse wave signal exceeds the preset threshold V_TH. If the amplitude value does not exceed the preset threshold V_TH, the process ends.
If it is determined in step S20 that the amplitude value of the pulse wave signal exceeds the threshold V_TH, the processing unit 12 measures the time during which the amplitude value of the pulse wave signal exceeds the threshold V_TH in step S21 under the control of the body motion detector 105.
In step S22, determination is made as to whether or not the time during which the amplitude value of the pulse wave signal exceeds the threshold V_TH exceeds the time threshold T_TH. If it is determined that the time threshold T_TH is exceeded, the body motion detector 1052 proceeds to step S23.
Next, in step S23, the processing unit 12 turns on the body motion determination flag, sets an internal counter i to 0, and stops the operation of all the sensor units 130-2 to 130-n except the first sensor unit 130-1 that performs determination of a body motion, under the control of the body motion determination unit 105. The processing function of stopping the operation of the sensor units 130-2 to 130-n will be detailed in a second embodiment described later.
On the other hand, if it is determined in step S22 that the time during which the amplitude value of the pulse wave signal exceeds the threshold V_TH does not exceed the time threshold T_TH, the processing unit 12 proceeds to step S24.
In step S24, the processing unit 12 determines whether or not the current body motion determination flag is ON. If the current body motion determination is OFF, the process ends. If the current body motion determination is ON, the processing unit 12 counts up the internal counter i in step S25, and proceeds to step S26. In step S26, the processing unit 12 determines whether or not the value of the internal counter i is larger than a number-of-times threshold N_TH. If the value of the internal counter i is smaller than the number-of-times threshold N_TH, the process ends. If the value of the internal counter i is equal to or larger than the number-of-times threshold N_TH, the process proceeds to step S27.
In step S27, the processing unit 12 turns off the body motion determination flag and resumes the power supply to the sensor units whose operation has been stopped, to resume the operation of the sensor units, under the control of the body motion determination unit 105. The blood pressure monitor 1 returns to the state of performing the operation of detecting an occurrence of a body motion again.
In this manner, a state of an occurrence of a body motion can be detected by a relatively simple method, which is to evaluate an amplitude value of a waveform of a pulse wave signal, without providing an additional sensor device such as an acceleration sensor.
A value fixedly set in advance as an initial value may be used as each threshold for the detection of a body motion, or the threshold may be automatically calculated from an average value obtained when a pulse wave is properly acquired. For example, when a calibration mode is executed, data when there is no change in the waveform for a certain period of time, or data having a high correlation between a PTT value and blood pressure may be automatically extracted.
For the first detection method, a method that focuses on the time during which the amplitude value of the waveform of the pulse wave signal exceeds the threshold V_TH is described above; however, the first detection method may focus on the time during which the amplitude value of the waveform of the pulse wave signal is equal to or less than the threshold V_TH in
(3-2) Second Detection Method
For example, in the second detection method, when a repetition cycle of a received pulse wave signal exceeds a preset time range, that is, when a waveform interval is outside a predetermined range, it is determined that a body motion has occurred. When the waveform interval falls within a preset range, it is determined that the body motion has stopped. For example, a time point at which the amplitude value of the pulse wave exceeds the preset threshold V_TH can be set as a reference point in determining the repetition cycle of the waveform.
In
When the repetition cycle of the waveform is continuously observed, the interval between t24 and t25 becomes smaller than the minimum threshold T_TH_MIN (T<T_TH_MIN). Therefore, at t25, it is determined that noise caused by a body motion is superimposed (a low-frequency component of the body motion is superimposed on the waveform=there is a body motion), and the body motion determination flag is turned on. Subsequently, since the interval between t25 and t26 is larger than the maximum threshold T_TH_MAX (T>T_TH_MAX), it is determined that noise is still superimposed at t26, and the body motion determination flag is kept ON. Since the interval between t26 and t27 is smaller than T_TH_MIN (T<T_TH_MIN), the body motion determination flag remains ON. Next, since the interval between t27 and t28 falls within the preset range (T_TH_MIN<T<T_TH_MAX) at t28, it is determined that the body motion has disappeared to an acceptable level (i.e., it is determined that there is no body motion), and the body motion determination flag is reset to OFF.
Regarding the determination of the stoppage of the body motion by the second detection method, the example in
(3-3) Third Detection Method
In the third detection method, a state of an occurrence of a body motion affecting measurement of a pulse wave is detected based only on an amplitude value of a received pulse wave signal.
In the third detection method, when an amplitude value of a received pulse wave signal exceeds a preset amplitude-value range, it is determined that a body motion has occurred. Also, in the third detection method, when the range of the amplitude value is continuously within a predetermined range for a certain period of time, it is determined that the body motion has stopped.
In regard to the third detection method, the signal intensity has a value lower than the intensity threshold V_TH at the time point t31, as shown in
The signal intensity of the pulse wave signal exceeds the intensity threshold V_TH at the time point t32, falling within the acceptable range. However, in this example, the body motion determination flag is not reset to OFF immediately, but at the time point t33 after it is determined that the signal intensity of the pulse wave signal is continuously within an acceptable range for a certain period of time (i.e., determined that there is no change in the determination result for a certain period of time).
In the method described above, it is determined that a body motion has occurred when the amplitude value of the waveform of the pulse wave signal exceeds the preset amplitude-value range. However, it may be determined that a body motion has occurred when the amplitude value of the waveform of the pulse wave signal does not exceed the preset second amplitude-value range. That is, when it is determined that the acquired pulse wave signal does not have a sufficient amplitude, it can be presumed that a noise component caused by a body motion is superimposed. As described above, if the polarity of the signal is reversed, the detailed determination conditions may be reversed.
(3-4) Fourth Detection Method
In the fourth detection method, a state of an occurrence of a body motion affecting measurement of a pulse wave is detected based on a difference between amplitude values of waveforms in respective repetition intervals.
In the fourth detection method, when a difference between an amplitude value of a waveform in the first repetition interval and an amplitude value of a waveform in the second repetition interval exceeds a preset range, it is determined that a body motion has occurred. Also, in the fourth detection method, it is determined that the body motion has stopped when the difference in the amplitude value between the repetition intervals is within a preset range. For example, the repetition interval may be set based on the rising of the peak of the wave, as shown in
In regard to the fourth detection method, a difference in the peak value between an interval T2 and an interval T1, for example, which is one interval ahead in time, is evaluated, in the interval T2, as the difference in the amplitude value, as shown in
(3-5) Fifth Detection Method
In the fifth detection method, a state of an occurrence of a body motion affecting measurement of a pulse wave is detected based on a spectrum intensity of a predetermined frequency band of a received pulse wave signal in each preset time interval.
In the fifth detection method, spectrum analysis such as fast Fourier transform (FFT) is performed on a received waveform cut out at one-second intervals, for example, and a frequency spectrum intensity of a band including the frequency of a pulse wave (a pulse wave is usually 0.5 to 10 Hz) is calculated. When the spectrum intensity of the frequency band or an average value of the intensity exceeds a predetermined range, it is determined that a body motion has occurred. Also, in the fifth detection method, it is determined that the body motion has stopped when the spectrum intensity or the average value of the intensity is continuously within a predetermined range N times.
In regard to the fifth detection method, the spectrum intensity in the frequency band of 0.5 to 10 Hz decreases in the interval T3, and the spectrum intensity is a very small value in the intervals T4 to T5, as shown in
(3-6) Sixth Detection Method
In the sixth detection method, a state of an occurrence of a body motion affecting measurement of a pulse wave is detected based on a shape of a waveform of a received pulse wave signal in each repetition interval.
In the sixth detection method, a correlation value between a shape of a waveform of a pulse wave signal in a certain repetition interval and a reference waveform stored in advance is obtained, and when the correlation value is equal to or less than a preset correlation value, it is determined that a body motion has occurred. As another detection method, a correlation value between a shape of a waveform of a pulse wave signal in a certain repetition interval and a shape of a waveform of a pulse wave signal in another repetition interval (e.g., an interval in which it is known that no body motion has occurred), that is, autocorrelation is obtained, and when the correlation value is equal to or less than a preset correlation value, it is determined that a body motion has occurred.
In the sixth detection method, when a correlation value between a shape of a waveform in any interval and a shape of a reference waveform or an autocorrelation value of a shape of a waveform between two different intervals exceeds a preset correlation value, it is determined that the body motion has stopped. For example, the repetition interval may be set based on the rising of the peak of the waveform, as shown in
In regard to the sixth detection method, the correlation value becomes small in the interval T3, and the correlation value becomes very small in the intervals T4 to T5, as shown in
It is not always necessary to provide all the first to sixth detection methods described above, and any one of the methods may be provided. Each of the first to sixth detection methods may be used by discretionarily selecting and combining a method of detecting a body motion and a method of detecting a stop of the body motion.
In the first embodiment, the feature extractor 1051 extracts a feature of a waveform from the pulse wave signal PS1 output from the pulse wave detector 101-1, and the body motion detector 1052 detects a state of an occurrence of a body motion affecting measurement of a pulse wave based on the extracted feature of the waveform, as detailed above. Therefore, a body motion of a user can be detected by using an existing sensor without adding another motion sensor such as an acceleration sensor. As a result, the apparatus can be rendered simple, compact, and inexpensive.
The output unit 5 generates a display message, for example, indicating that a body motion is occurring or prompting the body motion to stop, based on the information indicating the detection result of the body motion, so that the display message is displayed on the display 50. As a result, the user can confirm his or her own motion state based on the display message and stop the body motion during measurement of the biological information.
Also, the output unit stores, for example, log information indicating a detection result of a state of an occurrence of a body motion in the body motion storage 143 in the storage unit 14, and transmits the log information to an external apparatus via a network. Therefore, for example, the user can make use of the detection result of the state of the occurrence of the body motion to know the amount of movement or the like, or a family member or a healthcare worker in a remote area can monitor the state of the motion of the user.
It is also possible to perform processing such as discarding or not using a blood pressure value measured in a state where a body motion is detected, for example, based on the log information indicating the detection result of the state of the occurrence of the body motion stored in the body motion storage 143.
The processing unit 12 is provided with an operation control unit 1053. The operation control unit 1053 detects a period in which a body motion is detected based on the detection result of the occurrence of the body motion by the body motion determination unit 105. Then, in the detection period, power supply circuitry (not shown) is controlled so as to cut power supply to each of the sensor units 130-2 to 130-n except the first sensor unit 130-1. Also, the operation control unit 1053 stops the processing operations of the pulse wave detectors 101-2 to 101-n corresponding to the sensor units 130-2 to 130-n to which power supply is cut off and the processing operation of the PTT calculator 103.
With the above configuration, power consumption by each of the sensor units 130-2 to 130-n except the first sensor unit 130-1 and power consumption by the processing operations of the pulse wave detectors 101-2 to 101-n and the PTT calculator 103 can be set to zero during the period in which an occurrence of a body motion is detected, thereby rendering it possible to suppress the battery consumption and extend the battery life.
The operation control unit 1053 is not limited to the above-described processing operation. The operation control unit 1053 may, for example, set an operation stop period having a preset length from the detection time point, and during the operation stop period, cut the power supply to all the sensor units 130-1 to 130-n in the sensing unit 13, and also stop the operations of all the pulse wave detectors 101-1 to 101-n and the PTT calculator 103 in the processing unit 12 when an occurrence of a body motion is detected. Thereby, the battery energy can be saved more effectively. Hereinafter, the operation modes in which power supply is controlled by the operation control unit 1053 are also collectively referred to as a “power-saving mode.”
A log relating to the operation stop period may be stored in a log storage in the storage unit 14. This renders it possible to calculate the total body motion time during the measurement period.
In the second embodiment, the operation control unit 1053 controls an operation of a predetermined functional unit of the blood pressure monitor 1 based on the state of the occurrence of the body motion detected by the body motion determination unit 105, as detailed above. For example, when it is determined that a body motion affecting measurement of a pulse wave has occurred, the operation control unit 1053 controls power supply circuitry (not shown) so as to cut power supply to the other units in the blood pressure monitor 1 except the processing unit 12 for a certain period of time set in advance. In addition, the operation control unit 1053, for example, controls the power supply circuitry so as to cut power supply to all the sensor units except the first sensor unit 130-1 in a period from the time when the occurrence of the body motion is detected to the time when the occurrence of the body motion is no longer detected. Therefore, it is possible to reduce wasteful power consumption caused by operating the sensor units during a period in which a body motion is occurring and measurement cannot be properly performed.
In general, if the measurement operation is always performed regardless of whether a body motion is stationary or is occurring, wasteful power consumption corresponding to the measurement time during the body motion may occur. In particular, a battery life is one of important design issues of wearable devices such as the blood pressure monitor described above. In the second embodiment, the power supply to each sensor unit and the like can be controlled according to the state of the occurrence of the body motion; therefore, an effective power-saving operation can be performed, and the battery life can be extended.
Also, the PTT calculator 103 and the blood pressure estimator 104 do not perform the processing of calculating a PTT and the processing of estimating a blood pressure value; therefore, an inaccurate blood pressure estimate value affected by the body motion is not stored in the measurement value storage 142. Therefore, the measurement accuracy of the blood pressure estimate value can be improved.
(1) Example of System Including Blood Pressure Monitor 1
For example, an indication of whether or not there is a body motion while the blood pressure monitor 1 is worn, an alarm, or the like may be displayed on the display 50 of the blood pressure monitor 1, or a detection result of whether or not there is a body motion, a state of transition to the power-saving mode, or the like may be transmitted to the portable terminal 10B and displayed on a display 158. Thereby, the blood pressure monitor 1 can output the state of the occurrence of the body motion from the indication of the display 158 of the portable terminal 10B. The aforementioned indication, or the like may also be displayed on both the display 50 and the display 158 of the blood pressure monitor 1. In addition, the portable terminal 10B may report information indicating whether or not there is an occurrence of a body motion or information indicating the operation mode of the blood pressure monitor 1 in other output modes including vibration of the portable terminal 10B or a sound. The calculated blood pressure and body motion log is not necessarily stored in the measurement value storage 142 and the body motion storage 143 of the blood pressure monitor 1, but may be stored in a storage of the portable terminal 10B or a storage 32A of the server 30. Alternatively, the calculated blood pressure and body motion log may be stored in two or more of these storages.
(2) In each of the above-described embodiments, the blood pressure monitor that estimates blood pressure from a pulse wave velocity PTT using at least two pairs of pulse wave sensors 130 is described. However, the embodiments of the present disclosure may be a pulse wave measurement apparatus including only one pair of pulse wave sensors (that is, one transmission antennas and one reception antenna).
(3) In each of the above-described embodiments, the pulse wave sensor 130 using a radio wave is described. However, a pulse wave sensor using another principle such as a photoelectric method or a piezoelectric method may also be used.
(4) In each of the above-described embodiments, the case where a pulse wave is measured in the radial artery 91 of the wrist is described as an example. However, a pulse wave may be measured in other parts such as the upper arm, the ankle, and the thigh.
(5) It is also conceivable that an operation of removing the blood pressure monitor 1 from the measurement site is detected by the body motion determination unit 105, thereby automatically shifting the apparatus 1 to the power-saving mode through the removal operation or turning off the power of the apparatus 1.
(6) Several examples in which the feature of the waveform of the pulse wave signal is compared with the preset threshold are described as methods of detecting a state of an occurrence of a body motion. However, detailed determination conditions may be reversed depending on the polarity of the signal, as described above. The features of the waveform described above can also be replaced by other equivalent or complementary features. In this manner, the detailed determination conditions illustrated as examples above can be variously modified in accordance with the circuitry design, the operating environment, and the like, and are not limited to the above embodiments.
While the embodiments of the present invention have been detailed, the foregoing description is merely illustrative of the present invention in all respects. It goes without saying that various improvements and modifications can be made without departing from the scope of the present invention. For example, the following modifications can be made. In the following description, the same components as those of the above-described embodiments are denoted by the same reference numerals, and description of the same points as those of the above-described embodiments is omitted as appropriate. The following modifications can be combined as appropriate.
A part or whole of each of the above-described embodiments may be described as, but is not limited to, what is described in the appendices below, in addition to what is described in the claims.
A biological information measurement apparatus including a hardware processor and a memory,
the biological information measurement apparatus configured to
the hardware processor configured to, by executing a program stored in the memory,
A biological information measurement method executed by an apparatus including a hardware processor and a memory storing a program for executing the hardware processor, the biological information measurement method including:
transmitting a radio wave to a measurement site of a living body;
receiving a reflected wave of the radio wave by the measurement site and outputting a waveform signal of the reflected wave; and
the hardware processor extracting information indicating a feature of a waveform from the waveform signal; and
the hardware processor detecting a state of an occurrence of a body motion of the living body affecting measurement of the biological information, based on the extracted information indicating the feature of the waveform.
A biological information measurement apparatus (1) for measuring biological information, the biological information measurement apparatus (1) including:
a transmitter (3) configured to transmit a radio wave to a measurement site of a living body;
a receiver (4) configured to receive a reflected wave of the radio wave by the measurement site and output a waveform signal of the reflected wave;
a feature extractor (1051) configured to extract information indicating a feature of a waveform from the waveform signal; and
a body motion detector (1052) configured to detect a state of an occurrence of a body motion of the living body affecting measurement of the biological information, based on the extracted information indicating the feature of the waveform.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-077082 | Apr 2018 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2019/014625 | 4/2/2019 | WO | 00 |
