Biological information estimation device and biological information estimation method

Abstract

To shorten a time required for estimating biological information without discriminating a living body.SOLUTION: A biological information estimating apparatus includes: a detection section which detects a pulse wave from a living body; a change section which detects frequency of the pulse wave detected after a start of a measurement period, detects the number of pulses by rounding off digits after the decimal point included in a result obtained by dividing a time elapsed from the start by the cycle, and ends the measurement period when the number of pulses becomes a set number; and an estimating section which estimates biological information from the pulse wave detected within the measurement period.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a biological information estimation device and a biological information estimation method. [Background technology]

[0002] Patent Document 1 discloses a blood pressure monitor. In this blood pressure monitor, a cuff is wrapped around the user's artery. A pulse wave signal is discriminated from the pressure inside the cuff, detected by a pressure sensor during the process of slowly depressurizing the cuff. A blood pressure value is determined from the pulse wave signal and the pressure value. In addition, in personal mode, measurement conditions for measuring the blood pressure value of a specific user and blood pressure value determination conditions for determining the specific user's systolic and diastolic blood pressure values ​​are set based on the specific user's past measurement results. This allows for a reduction in measurement time (abstract). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-185681 Summary of the Invention [Problem to be solved by the invention]

[0004] In the blood pressure monitor disclosed in Patent Document 1, the measurement time can be reduced only when the measurement conditions and blood pressure value determination conditions can be set based on the past measurement results of a specific user. In addition, in order to reduce the measurement time, it is necessary to identify the user.

[0005] The present disclosure has been made in view of this problem, and an object of one aspect of the present disclosure is to provide a biometric information estimation device and a biometric information estimation method that can reduce the time required to estimate biometric information without identifying a living body, for example. [Means for solving the problem]

[0006] A bioinformation estimation device according to one aspect of the present disclosure includes a detection unit that detects pulse waves from a living body, a modification unit that detects the frequency of the pulse waves detected after a measurement period has started, detects the number of pulses by rounding down any decimal points contained in the result of dividing the time elapsed since the start by the period, and ends the measurement period when the number of pulses reaches a set number, and an estimation unit that estimates bioinformation from the pulse waves detected during the measurement period.

[0007] A biological information estimation method according to another aspect of the present disclosure includes the steps of: a) detecting a pulse wave from a living body; b) detecting the frequency of the pulse wave detected after a measurement period has started, detecting the number of pulses by rounding down any decimal places contained in the result of dividing the time elapsed since the start by the period, and ending the measurement period when the number of pulses reaches a set number; and c) estimating biological information from the pulse wave detected within the measurement period. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram of a biological information estimation device according to a first embodiment. [Figure 2] 10 is a flowchart showing a first example of the flow of processing performed by a change unit included in the biological information estimation device of the first embodiment. [Figure 3] 10 is a graph showing an example of the timing at which the change unit included in the biological information estimation device of the first embodiment ends the measurement period when the pulse rate of the living body is slow. [Figure 4] 10 is a graph showing an example of the timing at which the change unit included in the biological information estimation device of the first embodiment ends the measurement period when the pulse rate of the living body is fast. [Figure 5] 10 is a graph showing a first example of selection of a maximum point performed by a change unit included in the biological information estimation device of the first embodiment. [Figure 6] 10 is a graph showing a first example of selection of a minimum point performed by a change unit included in the biological information estimation device of the first embodiment. [Figure 7]10 is a graph showing a second example of selection of a local maximum point performed by a change unit included in the biological information estimation device of the first embodiment. [Figure 8] 10 is a graph showing a second example of selection of a minimum point performed by a change unit included in the biological information estimation device of the first embodiment. [Figure 9] 10 is a flowchart showing a second example of the flow of processing performed by the change unit included in the biological information estimation device of the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same or equivalent elements are designated by the same reference numerals, and redundant description will be omitted.

[0010] 1. First embodiment 1.1 Biometric information estimation device FIG. 1 is a block diagram of a biological information estimation device according to the first embodiment.

[0011] The biological information estimation device 1 shown in FIG. 1 estimates biological information 12 of a living organism 11. The living organism 11 from which the biological information 12 is estimated is a human. The living organism 11 may also be an animal other than a human. The estimated biological information 12 indicates the state of the living organism 11. The biological information 12 includes a blood pressure 21 and a pulse rate 22. The biological information 12 may also include biological information other than the blood pressure 21 and the pulse rate 22.

[0012] As shown in FIG. 1, the biological information estimation device 1 includes a detection unit 31, a change unit 32, an estimation unit 33, and an output unit .

[0013] The detector 31 detects a pulse wave 41 from the living body 11 .

[0014] The change unit 32 changes the length of the measurement period based on the pulse rate of the living organism 11. This makes it possible to set the length of the measurement time to a length appropriate for the pulse rate of the living organism 11. The change unit 32 changes the length of the measurement period based on the rate of periodic time change of the pulse wave 41, utilizing the fact that the rate of periodic time change of the pulse wave 41 reflects the pulse rate. The change unit 32 shortens the length of the measurement period as the pulse rate increases. This makes it possible to shorten the time required to estimate the biometric information 12 of the living organism 11 without identifying the living organism 11. For example, this time can be set to 10 seconds or less.

[0015] The estimation unit 33 estimates the biological information 12 from the pulse wave 41 detected within the measurement period.

[0016] The output unit 34 outputs the estimated biometric information 12. The output unit 34 is configured with a display that displays a screen showing the biometric information 12, a speaker that emits a sound showing the biometric information 12, a transmission circuit that transmits a signal showing the biometric information 12, etc.

[0017] 1.2 Detection section The detection unit 31 detects a pulse wave 41 from a part of the living body 11. The part from which the pulse wave 41 is detected is the fingertips, palms, soles, cheeks, forehead, nose, or chin. The part may be a part other than the fingertips, palms, soles, cheeks, forehead, nose, or chin. The detection unit 31 may detect the pulse wave 41 from one part, or may detect the pulse wave 41 from multiple parts simultaneously. The multiple parts may be the fingertips of the left hand and the fingertips of the right hand, or two or more parts selected from the cheeks, forehead, nose, etc. included in the face, or the fingertips and face. The detection unit 31 preferably detects the pulse wave 41 in real time.

[0018] In the first example of the present disclosure, the detection unit 31 includes a contact sensor.

[0019] The contact sensor comes into contact with the fingertip of the living body 11 and detects a pulse wave 41 from the fingertip.

[0020] The contact sensor includes a light emitting portion and a light receiving portion.

[0021] The light-emitting unit emits light. The emitted light may be either visible light or invisible light. Visible light is red light, green light, etc. Invisible light is infrared light, etc. The light-emitting unit is composed of a light-emitting diode (LED) or the like.

[0022] The light receiving unit receives light generated when the fingertip in contact with the detection unit 31 diffusely reflects the light emitted by the light emitting unit, and outputs a signal corresponding to the amount of light received. The change in the magnitude of the output signal over time is the detected pulse wave 41. The amount of light reflects the amount of blood flowing through the blood vessels in the fingertip. Therefore, the detected pulse wave 41 reflects the change in the amount of blood over time. The light receiving unit is composed of a photodiode, etc.

[0023] The detector 31 may include a signal processor that performs signal processing on the detected pulse wave 41 to remove noise components from the pulse wave 41. The signal processing performed includes processing to remove low-frequency noise components with long periods, processing to remove high-frequency noise components with short periods, etc. The former processing includes high-pass filtering and trend removal processing, etc. The latter processing includes low-pass filtering and the like. The processing performed may be either analog signal processing performed by an electronic circuit or digital signal processing performed by a processor.

[0024] In the second example of the present disclosure, the detection unit 31 includes an imaging unit and an image processing unit.

[0025] The imaging unit obtains an image by capturing an image of the living body 11. The imaging unit is configured with an RGB camera or the like.

[0026] The image processing unit determines whether or not the living body 11 is captured in the obtained image, and if it determines that the living body 11 is captured in the image, it outputs the pixel values ​​of the pixels in which the living body 11 is captured. The change over time in the output pixel values ​​represents the detected pulse wave 41. The image processing unit is composed of a central processing unit (CPU) that executes a program, etc. All or part of the processing performed by the image processing unit may be performed by a dedicated electronic circuit.

[0027] When detecting pulse waves 41 from the fingertips of the left and right hands simultaneously, the detection unit 31 is provided with a contact sensor for the fingertips of the left hand and a contact sensor for the fingertips of the right hand. The contact sensor for the fingertips of the left hand comes into contact with the fingertips of the left hand and detects pulse waves 41 from the touched fingertips of the left hand. The contact sensor for the fingertips of the right hand comes into contact with the fingertips of the right hand and detects pulse waves 41 from the touched fingertips of the right hand.

[0028] When the detection unit 31 simultaneously detects pulse waves 41 from two or more parts included in the face, the imaging unit captures an image of the face of the living body 11 to obtain a facial image. The image processing unit calculates the pulse wave 41 from the pixel values ​​of pixels in which each of the two or more parts is captured.

[0029] When the detection unit 31 simultaneously detects the pulse wave 41 from the fingertip and the face, the contact sensor comes into contact with the fingertip of the living body 11 and detects the pulse wave 41 from the contacted fingertip. The imaging unit also captures an image of the face of the living body 11 to obtain an image of the face. The image processing unit also calculates the pulse wave 41 from the pixel values ​​of pixels in which the face is captured.

[0030] 1.3 Changes The change unit 32 detects the number of pulses included in the pulse wave 41 detected after the measurement period has started, and ends the measurement period when the number of detected pulses reaches a set number. The change unit 32 is configured with a CPU or the like that executes a program. All or part of the processing performed by the change unit 32 may be performed by a dedicated electronic circuit.

[0031] The detected pulse wave 41 indicates a change over time in the detected amount detected from the living body 11. The change over time in the pulse wave 41 includes a periodic change over time associated with the periodic pulsation of the heart of the living body 11. A pulse included in the pulse wave 41 indicates a change over time in the detected amount during a period of time required for one pulsation of the heart of the living body 11, extracted from the pulse wave 41. Both ends of the pulse may be either a minimum point where the detected amount is minimal or a maximum point where the detected amount is maximal. Therefore, both ends of the pulse may be either a valley or a peak in the waveform of the pulse wave 41.

[0032] Even if the number of pulses included in the pulse wave 41 detected during the measurement period is one, the estimation unit 33 can estimate the biological information 12 from one pulse. Therefore, the set number may be 1. However, the larger the number of pulses, the higher the accuracy of the estimation of the biological information 12 by the estimation unit 33. Therefore, the set number is preferably 2 or more, and more preferably 5 or more.

[0033] 1.4 Processing performed by the modification unit FIG. 2 is a flowchart showing a first example of the flow of processing performed by the change unit included in the biological information estimation apparatus of the first embodiment.

[0034] The change unit 32 executes steps S101 to S103 shown in FIG.

[0035] In step S101, the change unit 32 detects the number of pulses contained in the pulse wave 41 detected after the measurement period has started.

[0036] In the next step S102, the change unit 32 determines whether the number of detected pulses has reached the set number. If it is determined that the number of detected pulses has reached the set number, step S103 is executed. If it is determined that the number of detected pulses has not reached the set number, step S101 is executed again.

[0037] In step S103, the change unit 32 ends the measurement period.

[0038] Through steps S101 to S103, the change unit 32 continues the measurement period without ending it until the number of pulses contained in the pulse wave 41 detected after the measurement period has started reaches the set number, and ends the measurement period in conjunction with the number of pulses reaching the set number.

[0039] 1.5 Changes in the length of the measurement period depending on pulse rate Fig. 3 is a graph illustrating an example of timing at which the change unit included in the biological information estimation device of the first embodiment ends the measurement period when the pulse rate of the living body is slow. Fig. 4 is a graph illustrating an example of timing at which the change unit included in the biological information estimation device of the first embodiment ends the measurement period when the pulse rate of the living body is fast.

[0040] 3 and 4, the horizontal axis represents time, and the vertical axis represents the amount of detection detected from the living body 11.

[0041] In the examples shown in FIGS. 3 and 4 , the change unit 32 detects the number of pulses 51 included in the pulse wave 41 detected after the measurement period started at time 0, and ends the measurement period when the number of detected pulses 51 reaches five. Therefore, the change unit 32 ends the measurement period when five times the period of the pulse wave 41 has elapsed since time 0. Therefore, as shown in FIG. 3 , when the pulse of the living body 11 is slow and the period of the pulse wave 41 is long, the change unit 32 ends the measurement period at a relatively late time ts. On the other hand, as shown in FIG. 4 , when the pulse of the living body 11 is fast and the period of the pulse wave 41 is short, the change unit 32 ends the measurement period at a relatively early time tf. The estimation unit 33 estimates the biological information 12 from the five pulses 51 detected during the measurement period.

[0042] The change unit 32 performs signal processing on the pulse wave 41 to detect the number of pulses included in the pulse wave 41. The signal processing performed includes peak detection, frequency analysis, and the like.

[0043] 1.6 Detecting the number of pulses by peak detection When detecting the number of pulses 51 by performing peak detection on the pulse wave 41, the modification unit 32 extracts maximum points from the pulse wave 41 and defines a portion of the pulse wave 41 between adjacent maximum points as one pulse 51. Alternatively, the modification unit 32 extracts minimum points from the pulse wave 41 and defines a portion of the pulse wave 41 between adjacent minimum points as one pulse 51.

[0044] Fig. 5 is a graph showing a first example of selection of a maximum point performed by a change unit included in the biometric information estimation device of the first embodiment. Fig. 6 is a graph showing a first example of selection of a minimum point performed by a change unit included in the biometric information estimation device of the first embodiment.

[0045] 5 and 6, the horizontal axis represents time, and the vertical axis represents the amount of detection detected from the living body 11.

[0046] In a first example, as shown in FIG. 5 , the change unit 32 selects multiple maximum points 61 from the pulse wave 41 detected after the start of the measurement period in descending order of height so that the time interval T1 between adjacent maximum points 61 falls within a set range, and defines the portion of the pulse wave 41 between the adjacent maximum points 61 as one pulse 51. The range is set based on a typical pulse rate. A typical pulse rate is 50 to 90 beats per minute. This allows for the selection of a global maximum point 61 that is suitable as a separator between two adjacent pulses 51. It also prevents the selection of a local maximum point 62 that is not suitable as a separator. Alternatively, as shown in FIG. 6 , the change unit 32 selects multiple minimum points 71 from the pulse wave 41 detected after the start of the measurement period in descending order of depth so that the time interval T2 between adjacent minimum points 71 falls within a set range, and defines the portion of the pulse wave 41 between the adjacent minimum points 71 as one pulse 51. The range is set based on a typical pulse rate. A typical pulse rate is 50 to 90 beats per minute. This makes it possible to select a global minimum point 71 that is suitable as a separator between two adjacent pulses 51. It also makes it possible to prevent the selection of a local minimum point 72 that is not suitable as the separator.

[0047] Fig. 7 is a graph showing a second example of selection of a maximum point performed by the change unit included in the biometric information estimation device of the first embodiment. Fig. 8 is a graph showing a second example of selection of a minimum point performed by the change unit included in the biometric information estimation device of the first embodiment.

[0048] 7 and 8, the horizontal axis represents time, and the vertical axis represents the amount of detection from the living body 11.

[0049] In a second example, as shown in FIG. 7 , the change unit 32 selects multiple maximum points 92 having heights equal to or greater than a set height 91 from the pulse wave 41 detected after the measurement period has started, and defines the portion of the pulse wave 41 between adjacent maximum points 92 as one pulse 51. The height 91 is set based on the amplitude of the pulse wave 41. This makes it possible to select a global maximum point 92 suitable as a separator between two adjacent pulses 51. This also makes it possible to prevent the selection of a local maximum point 93 that is not suitable as a separator. Alternatively, as shown in FIG. 8 , the change unit 32 selects multiple minimum points 102 having depths equal to or greater than a set depth 101 from the pulse wave 41 detected after the measurement period has started, and defines the portion of the pulse wave 41 between adjacent minimum points 102 as one pulse 51. The depth 101 is set based on the amplitude of the pulse wave 41. This makes it possible to select a global minimum point 102 suitable as a separator between two adjacent pulses 51. Moreover, it is possible to prevent the selection of a local minimum point 103 that is not suitable as the delimiter.

[0050] 1.7 Detecting the number of pulses by frequency analysis When detecting the number of pulses 51 by performing frequency analysis on pulse wave 41, change unit 32 detects the period of pulse wave 41 and detects the number of pulses 51 by dividing the time when pulse wave 41 was detected, i.e., the time elapsed since the start of the reception period, by the detected period. The decimal points included in the result of dividing the time when pulse wave 41 was detected by the detected period may be truncated so that the number of pulses 51 becomes an integer. For example, if the time when pulse wave 41 was detected is 3 seconds and the detected period is 0.9 seconds, the decimal points included in the result of dividing the time when pulse wave 41 was detected by the detected period (3 / 0.9=3.333...) may be truncated, and the number of pulses 51 may be set to 3.

[0051] The change unit 32 detects the period of the pulse wave 41 by performing processing such as fast Fourier transform (FFT) and minimum entropy method (MEM) on the pulse wave 41.

[0052] 1.8 Determining the length of the measurement period depending on the frequency The change unit 32 may detect the frequency of the pulse wave 41 detected after the measurement period has started, and shorten the length of the measurement period as the detected frequency becomes higher.

[0053] The change unit 32 detects the frequency of the pulse wave 41 by performing FFT, MEM, or other processing on the pulse wave 41.

[0054] FIG. 9 is a flowchart showing a second example of the flow of processing performed by the change unit included in the biological information estimation device of the first embodiment.

[0055] Change unit 32 detects the frequency of pulse wave 41, and if the length of the measurement period is to be shortened as the detected frequency becomes higher, change unit 32 executes steps S111 to S114 shown in FIG.

[0056] In step S111, the change unit 32 detects the frequency of the pulse wave 41 detected after the measurement period has started.

[0057] In the next step S112, the change unit 32 determines the length of the measurement period according to the detected frequency. The change unit 32 shortens the length of the measurement period as the detected frequency increases. For example, the change unit 32 determines the length of the measurement period by multiplying the reciprocal of the detected frequency by a coefficient. The coefficient to be multiplied is 1 or more, preferably 2 or more, and more preferably 5 or more.

[0058] In the next step S113, the change unit 32 determines whether or not a time having the determined length has elapsed since the start of the measurement period. If it is determined that the time has elapsed, step S114 is executed. If it is determined that the time has not elapsed, step S111 is executed again.

[0059] In step S114, the change unit 32 ends the measurement period.

[0060] Through steps S111 to S114, the change unit 32 continues the measurement period without ending it until a sufficient amount of time has elapsed since the start of the measurement period, and ends the measurement period in conjunction with the sufficient amount of time having elapsed.

[0061] 1.9 Estimation part The estimation unit 33 estimates the blood pressure 21 from the waveform and / or frequency dependency of the pulse wave 41 detected within the measurement period. When the detection unit 31 simultaneously detects pulse waves 41 from two or more locations, the estimation unit 33 may estimate the blood pressure 21 from the correlation between the pulse waves 41 simultaneously detected from two or more locations. This allows the biological information estimation device 1 to estimate the biological information 12 without using a cuff.

[0062] Furthermore, the estimation unit 33 estimates the pulse rate 22 from the number of pulses 51 included in the pulse wave 41 detected within the measurement period. For example, the estimation unit 33 estimates the pulse rate 22 by dividing the number of pulses 51 by the length of the measurement period.

[0063] The estimation unit 33 is a CPU that executes a program, etc. All or part of the processing performed by the change unit 32 may be performed by a dedicated electronic circuit.

[0064] 1.10 Comparison with cuff-type electronic blood pressure monitors In a cuff-type electronic blood pressure monitor, the pressure inside the cuff is varied. The cuff itself acts as a sensor to detect a pulse wave. Blood pressure is then estimated from the detected pulse wave. In an oscillometric blood pressure monitor, the pressure inside a cuff wrapped around the arm is varied. Blood pressure is estimated from the amplitude of the detected pulse wave. To estimate blood pressure, the pressure inside the cuff must be gradually varied while detecting pulse waves over multiple cycles. Measurement time can be shortened by varying the pressure inside the cuff at the maximum speed that can detect the number of pulses required to estimate blood pressure. However, this maximum speed can only be calculated if the user's blood pressure and pulse rate are known. Therefore, measurement time cannot be shortened when estimating the blood pressure of a user using an electronic blood pressure monitor for the first time. To shorten measurement time, it is necessary to store previous blood pressure and pulse rate estimation results for each user. It is also necessary to identify whether the user has previously used an electronic blood pressure monitor and whether the user has previously used an electronic blood pressure monitor.

[0065] In contrast, in the biological information estimation device 1, the information used to estimate the blood pressure 21 and pulse rate 22 and the information used to determine the length of the measurement period are obtained from the pulse wave 41 detected after the measurement period has started. Therefore, in the biological information estimation device 1, it is not necessary to obtain this information before the measurement period starts. This eliminates the effort and time required to obtain information about the living body 11 in advance.

[0066] The present disclosure is not limited to the above-described embodiments, and may be replaced with a configuration that is substantially the same as the configuration shown in the above-described embodiments, a configuration that has the same effect, or a configuration that can achieve the same purpose. [Explanation of symbols]

[0067] 1 Biometric information estimation device, 11 biological body, 12 biological information, 21 blood pressure, 22 pulse rate, 31 detection unit, 32 modification unit, 33 estimation unit, 34 output unit, 41 pulse wave, 51 pulse, 61 maximum point, 62 maximum point, 71 minimum point, 72 minimum point, 91 height, 92 maximum point, 93 maximum point, 101 depth, 102 minimum point, 103 minimum point.

Claims

1. a detection unit that detects a pulse wave from a living body; a change unit that detects the period of the pulse wave detected after the start of a measurement period, detects the number of pulses by dividing the time elapsed since the start by the period and rounding down the decimal points included in the result, and ends the measurement period when the number of pulses reaches a set number; an estimation unit that estimates biological information from the pulse wave detected within the measurement period; Equipped with Biometric information estimation device.

2. The change unit repeatedly detects the period of the pulse wave during the measurement period. The biological information estimation device according to claim 1 .

3. The biological information includes blood pressure. The biological information estimation device according to claim 1 or 2.

4. The biological information includes a pulse rate. The biological information estimation device according to claim 1 or 2.

5. a) detecting a pulse wave from a living body; b) detecting the period of the pulse wave detected after the start of a measurement period, detecting the number of pulses by dividing the time elapsed since the start by the period and rounding down the decimal points included in the result, and ending the measurement period when the number of pulses reaches a set number; c) estimating biological information from the pulse wave detected during the measurement period; Equipped with Biometric information estimation method.

Images